Cis-epistasis at the LPA locus and risk of cardiovascular diseases.

Zeng L, Moser S, Mirza-Schreiber N, Lamina C, ... MüLler-Myhsok B, Schunkert H
Aims
Coronary artery disease (CAD) has a strong genetic predisposition. However, despite substantial discoveries made by genome-wide association studies (GWAS), a large proportion of heritability awaits identification. Non-additive genetic-effects might be responsible for part of the unaccounted genetic variance. Here we attempted a proof-of-concept study to identify non-additive genetic effects, namely epistatic interactions, associated with CAD.
Methods and results
We tested for epistatic interactions in ten CAD case-control studies and UK Biobank with focus on 8,068 SNPs at 56 loci with known associations with CAD risk. We identified a SNP pair located in cis at the LPA locus, rs1800769 and rs9458001, to be jointly associated with risk for CAD (odds ratio [OR]=1.37, p = 1.07 × 10-11), peripheral arterial disease (OR = 1.22, p = 2.32 × 10-4), aortic stenosis (OR = 1.47, p = 6.95 × 10-7), hepatic lipoprotein(a) (Lp(a)) transcript levels (beta = 0.39, p = 1.41 × 10-8), and Lp(a) serum levels (beta = 0.58, p = 8.7 × 10-32), while individual SNPs displayed no association. Further exploration of the LPA locus revealed a strong dependency of these associations on a rare variant, rs140570886, that was previously associated with Lp(a) levels. We confirmed increased CAD risk for heterozygous (relative OR = 1.46, p = 9.97 × 10-32) and individuals homozygous for the minor allele (relative OR = 1.77, p = 0.09) of rs140570886. Using forward model selection, we also show that epistatic interactions between rs140570886, rs9458001, and rs1800769 modulate the effects of the rs140570886 risk allele.
Conclusions
These results demonstrate the feasibility of a large-scale knowledge-based epistasis scan and provide rare evidence of an epistatic interaction in a complex human disease. We were directed to a variant (rs140570886) influencing risk through additive genetic as well as epistatic effects. In summary, this study provides deeper insights into the genetic architecture of a locus important for cardiovascular diseases.
Translational perspective
Genetic variants identified by GWAS studies explain about a quarter of the heritability of coronary artery disease by additive genetic effects. Our study demonstrates that non-additive effects contribute to the genetic architecture of the disease as well and identifies complex interaction patterns at the LPA locus, which affect LPA expression, Lp(a) plasma levels and risk of atherosclerosis. This proof-of-concept study encourages systematic searches for epistatic interactions in further studies to shed new light on the aetiology of the disease.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 19 Apr 2021; epub ahead of print

Extracellular histones are a target in myocardial ischaemia reperfusion injury.

Shah M, He Z, Rauf A, Kalkhoran SB, ... Davidson SM, Yellon D
Acute myocardial infarction causes lethal cardiomyocyte injury during ischaemia and reperfusion (I/R). Histones have been described as important Danger Associated Molecular Proteins (DAMPs) in sepsis.
Aims:
The objective of this study was to establish whether extracellular histone release contributes to myocardial infarction. Methods and results Isolated, perfused rat hearts were subject to I/R. Nucleosomes and histone H4 release was detected early during reperfusion. Sodium-β-O-Methyl cellobioside sulfate (mCBS), a newly developed histone-neutralising compound, significantly reduced infarct size whilst also reducing the detectable levels of histones. Histones were directly toxic to primary adult rat cardiomyocytes in vitro. This was prevented by mCBS, or HIPe, a recently described, histone-H4 neutralizing peptide, but not by an inhibitor of TLR4, a receptor previously reported to be involved in DAMP-mediated cytotoxicity. Furthermore, TLR4-reporter HEK293 cells revealed that cytotoxicity of histone H4 was independent of TLR4 and NF-κB. In an in vivo rat model of I/R, HIPe significantly reduced infarct size.
Conclusion:
Histones released from the myocardium are cytotoxic to cardiomyocytes, via a TLR4-independent mechanism. The targeting of extracellular histones provides a novel opportunity to limit cardiomyocyte death during I/R injury of the myocardium. Translational perspective Acute myocardial infarction causes lethal cardiomyocyte injury during ischaemia and reperfusion (I/R). New approaches are needed to prevent cardiomyocyte injury and limit final infarct size. We show that histones released from damaged cells, and histone-H4 in particular, causes rapid cardiomyocyte death during I/R. mCBS, a compounds targeting histones non-specifically, was cardioprotective in ex vivo rat hearts, while HIPe, a targeting histone H4 specifically, was cardioprotective in an in vivo rat model. HIPe may have potential as a therapeutic agent in the setting of acute myocardial infarction.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 19 Apr 2021; epub ahead of print

Cell Therapy in Patients with Heart Failure: A Comprehensive Review and Emerging Concepts.

Bolli R, Solankhi M, Tang XL, Kahlon A
This review summarizes the results of clinical trials of cell therapy in patients with heart failure (HF). In contrast to acute myocardial infarction (where results have been consistently negative for more than a decade), in the setting of HF the results of Phase I-II trials are encouraging, both in ischemic and nonischemic cardiomyopathy. Several well-designed Phase II studies have met their primary endpoint and demonstrated an efficacy signal, which is remarkable considering that only one dose of cells was used. That an efficacy signal was seen 6-12 months after a single treatment provides a rationale for larger, rigorous trials. Importantly, no safety concerns have emerged. Amongst the various cell types tested, mesenchymal stromal cells (MSCs) derived from bone marrow, umbilical cord, or adipose tissue show the greatest promise. In contrast, embryonic stem cells are not likely to become a clinical therapy. Unfractionated bone marrow cells and cardiosphere-derived cells have been abandoned. The cell products used for HF will most likely be allogeneic. New approaches, such as repeated cell treatment and intravenous delivery, may revolutionize the field. As is the case for most new therapies, the development of cell therapies for HF has been slow, plagued by multifarious problems, and punctuated by many setbacks; at present, the utility of cell therapy in HF remains to be determined. What the field needs is rigorous, well-designed Phase III trials. The most important things to move forward are to keep an open mind, avoid preconceived notions, and let ourselves be guided by the evidence.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 18 Apr 2021; epub ahead of print

Cardiovascular rna markers and artificial intelligence may improve covid-19 outcome: position paper from the eu-cardiorna cost action ca17129.

Badimon L, Robinson EL, Jusic A, Carpusca I, ... Devaux Y, EU-CardioRNA COST Action CA17129
The coronavirus disease 2019 (COVID-19) pandemic has been as unprecedented as unexpected, affecting more than 105 million people worldwide as of February 8th, 2020 and causing more than 2.3 million deaths according the World Health Organization. Not only affecting the lungs and provoking acute respiratory distress, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is able to infect multiple cell types including cardiac and vascular cells. Hence a significant proportion of infected patients develop cardiac events such as arrhythmias and heart failure. Patients with cardiovascular comorbidities are at highest risk of cardiac death. To face the pandemic and limit its burden, health authorities have launched several fast track calls for research projects aiming to develop rapid strategies to combat the disease, as well as longer-term projects to prepare for the future. Biomarkers have the possibility to aid in clinical decision making and tailoring healthcare in order to improve patient quality of life. The biomarker potential of circulating RNAs has been recognized in several disease conditions, including cardiovascular disease. RNA biomarkers may be useful in the current COVID-19 situation. The discovery, validation and marketing of novel biomarkers, including RNA biomarkers, require multi-centre studies by large and interdisciplinary collaborative networks, involving both the academia and the industry. Here, members of the EU-CardioRNA COST Action CA17129 summarize the current knowledge about the strain that COVID-19 places on the cardiovascular system and discuss how RNA biomarkers can aid to limit this burden. They present the benefits and challenges of the discovery of novel RNA biomarkers, the need for networking efforts and the added value of artificial intelligence to achieve reliable advances.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 10 Apr 2021; epub ahead of print

Single cell dual-omics reveals the transcriptomic and epigenomic diversity of cardiac non-myocytes.

Wang L, Yang Y, Ma H, Xie Y, ... Liu J, Qian L
Aims
The precise cellular identity and molecular features of non-myocytes (nonCM) in a mammalian heart at a single cell level remain elusive. Depiction of epigenetic landscape with transcriptomic signatures using the latest single-cell multi-omics has the potential to unravel the molecular programs underlying the cellular diversity of cardiac non-myocytes. Here, we characterized the molecular and cellular features of cardiac nonCM populations in the adult murine heart at the single cell level.
Methods and results
Through single-cell dual omics analysis, we mapped the epigenetic landscapes, characterized the transcriptomic profiles and delineated the molecular signatures of cardiac nonCMs in the adult murine heart. Distinct cis-regulatory elements and trans-acting factors for the individual major nonCM cell types (endothelial cells, fibroblast, pericytes and immune cells) were identified. In particular, unbiased sub-clustering and functional annotation of cardiac fibroblasts (FB) revealed extensive FB heterogeneity and identified FB subtypes with functional states related to cellular response to stimuli, cytoskeleton organization and immune regulation, respectively. We further explored the function of marker genes Hsd11b1 and Gfpt2 that label major FB sub-populations and determined the distribution of Hsd11b1+ and Gfp2+ FBs in murine healthy and diseased hearts.
Conclusions
In summary, we characterized the nonCM cellular identity at the transcriptome and epigenome levels using single-cell omics approaches and discovered previously unrecognized cardiac fibroblast subpopulations with unique functional states.
Translational perspective
Our research identified discrete cell types of nonCM in the heart and differentially expressed genes with regulatory factors. Unveiling the heterogeneity of nonCMs and molecular signatures of each cell type or subtypes allows for study, precise capture and manipulation of specific cell type(s) in heart and will provide insights into the development of therapeutics for cardiovascular diseases.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 10 Apr 2021; epub ahead of print

FAK in the nucleus prevents VSMC proliferation by promoting p27 and p21 expression via Skp2 degradation.

Jeong K, Murphy JM, Erin Ahn EY, Steve Lim ST
Aim
Vascular smooth muscle cells (VSMCs) normally exhibit a very low proliferative rate. Vessel injury triggers VSMC proliferation, in part, through focal adhesion kinase (FAK) activation, which increases transcription of cyclin D1, a key activator for cell cycle-dependent kinases (CDKs). At the same time, we also observe that FAK regulates the expression of the CDK inhibitors (CDKIs) p27 and p21. However, the mechanism of how FAK controls CDKIs in cell cycle progression is not fully understood.
Methods and results
We found that pharmacological and genetic FAK inhibition increased p27 and p21 by reducing stability of S-phase kinase-associated protein 2 (Skp2), which targets the CDKIs for degradation. FAK N-terminal domain interacts with Skp2 and an APC/C E3 ligase activator, fizzy-related 1 (Fzr1) in the nucleus, which promotes ubiquitination and degradation of both Skp2 and Fzr1. Notably, overexpression of cyclin D1 alone failed to promote proliferation of genetic FAK kinase-dead (KD) VSMCs, suggesting that the FAK-Skp2-CDKI signaling axis is distinct from the FAK-cyclin D1 pathway. However, overexpression of both cyclin D1 and Skp2 enables proliferation of FAK-KD VSMCs, implicating that FAK ought to control both activating and inhibitory switches for CDKs. In vivo, wire injury activates FAK in the cytosol and increased Skp2 and decreased p27 and p21 levels.
Conclusions
Both pharmacological FAK and genetic FAK inhibition reduced Skp2 expression in VSMCs upon injury, which significantly reduced intimal hyperplasia through elevated expression of p27 and p21. This study revealed that nuclear FAK-Skp2-CDKI signaling negatively regulates CDK activity in VSMC proliferation.
Translational perspective
Increased VSMC proliferation contributes to pathological vessel narrowing in atherosclerosisand following vascular interventions. Blocking VSMC proliferation will reduce atherosclerosisprogression and increase patency of vascular interventions. We found that forced nuclear FAKlocalization by FAK inhibition reduced VSMC proliferation upon vessel injury. Nuclear FAKdecreased Skp2 protein expression by proteasomal degradation, thereby increasing theexpression of cell cycle inhibitors p27 and p21 and blocking cell cycle progression. This studyhas demonstrated the potential for FAK inhibitors in blocking VSMC proliferation to treat vessel narrowing diseases.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 10 Apr 2021; epub ahead of print

Effects of canagliflozin on myocardial infarction: a post hoc analysis of the CANVAS Program and CREDENCE trial.

Yu J, Li J, Leaver PJ, Arnott C, ... Neal B, Figtree GA
Aims
Given the benefits of sodium glucose co-transporter 2 inhibition (SGLT2i) in protecting against heart failure in diabetic patients, we sought to explore the potential impact of SGLT2i on the clinical features of patients presenting with myocardial infarction (MI) through a post-hoc analysis of CANVAS Program and CREDENCE trial.
Methods and results
Individuals with type 2 diabetes and history or high risk of cardiovascular disease (CANVAS Program) or type 2 diabetes and chronic kidney disease (CREDENCE) were included. The intervention was Canagliflozin 100 or 300 mg (combined in the analysis) or placebo. MI events were adjudicated as ST-elevation myocardial infarction (STEMI), non-STEMI as well as type 1 MI or type 2 MI. 421 first MI events in the CANVAS Program and 178 first MI events in the CREDENCE trial were recorded (83 fatal, 128 STEMI, 431 non-STEMI, and 40 unknown). No benefit of canagliflozin compared with placebo on time to first MI event was observed (HR 0.89; 95% CI 0.75, 1.05). Canagliflozin was associated with lower risk for non-STEMI (HR 0.78; 95% CI 0.65, 0.95) but suggested a possible increase in STEMI (HR 1.55; 95% CI 1.06, 2.27), with no difference in risk of type 1 or type 2 MI. There was no change in fatal MI (HR 1.22, 95% CI 0.78, 1.93).
Conclusions
Canagliflozin was not associated with a reduction in overall MI in the pooled CANVAS Program and CREDENCE trial population. The possible differential effect on STEMI and Non-STEMI observed in the CANVAS cohort warrants further investigation.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 06 Apr 2021; epub ahead of print

Novel insights into the electrophysiology of murine cardiac macrophages: relevance of voltage-gated potassium channels.

Simon-Chica A, Fernández MC, Wülfers EM, Lother A, ... Kohl P, Schneider-Warme F
Aims
Macrophages (MΦ), known for immunological roles such as phagocytosis and antigen presentation, have been found to electrotonically couple to cardiomyocytes (CM) of the atrio-ventricular node via Cx43, affecting cardiac conduction in isolated mouse hearts. Here, we characterise passive and active electrophysiological properties of murine cardiac resident MΦ, and model their potential electrophysiological relevance for CM.
Methods and results
We combined classic electrophysiological approaches with 3 D florescence imaging, RNA-sequencing, pharmacological interventions and computer simulations. We used Cx3cr1eYFP/+ mice wherein cardiac MΦ were fluorescently labelled. FACS-purified fluorescent MΦ from mouse hearts were studied by whole-cell patch-clamp. MΦ electrophysiological properties include: membrane resistance 2.2 ± 0.1 GΩ (all data mean±SEM), capacitance 18.3 ± 0.1 pF, resting membrane potential -39.6 ± 0.3 mV, and several voltage-activated, outward or inwardly-rectifying potassium currents. Using ion channel blockers (barium, TEA, 4-AP, margatoxin, XEN-D0103, DIDS), flow cytometry, immuno-staining and RNA-sequencing, we identified Kv1.3, Kv1.5 and Kir2.1 as channels contributing to observed ion currents. MΦ displayed four patterns for outward and two for inward-rectifier potassium currents. Additionally, MΦ showed surface expression of Cx43, a prerequisite for homo- and/or heterotypic electrotonic coupling. Experimental results fed into development of an original computational model to describe cardiac MΦ electrophysiology. Computer simulations to quantitatively assess plausible effects of MΦ on electrotonically coupled CM showed that MΦ can depolarise resting CM, shorten early and prolong late action potential duration, with effects depending on coupling strength and individual MΦ electrophysiological properties, in particular resting membrane potential and presence/absence of Kir2.1.
Conclusions
Our results provide a first electrophysiological characterisation of cardiac resident MΦ, and a computational model to quantitatively explore their relevance in the heterocellular heart. Future work will be focussed at distinguishing electrophysiological effects of MΦ-CM coupling on both cell types during steady-state and in patho-physiological remodelling, when immune cells change their phenotype, proliferate, and/or invade from external sources.
Translational perspective
Cardiac tissue contains resident macrophages (MΦ) which, beyond immunological and housekeeping roles, have been found to electrotonically couple via connexins to cardiomyocytes (CM), stabilising atrio-ventricular conduction at high excitation rates. Here, we characterise structure and electrophysiological function of murine cardiac MΦ and provide a computational model to quantitatively probe the potential relevance of MΦ-CM coupling for cardiac electrophysiology. We find that MΦ are unlikely to have major electrophysiological effects in normal tissue, where they would hasten early and slow late CM-repolarisation. Further work will address potential arrhythmogenicity of MΦ in patho-physiologically remodelled tissue containing elevated MΦ-numbers, incl. non-resident recruited cells.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 05 Apr 2021; epub ahead of print

SERCA2a stimulation by istaroxime improves intracellular Ca2+ handling and diastolic dysfunction in a model of diabetic cardiomyopathy.

Torre E, Arici M, Lodrini AM, Ferrandi M, ... Bianchi G, Rocchetti M
Aims
Diabetic cardiomyopathy is a multifactorial disease characterized by an early onset of diastolic dysfunction (DD) that precedes the development of systolic impairment. Mechanisms that can restore cardiac relaxation improving intracellular Ca2+ dynamics represent a promising therapeutic approach for cardiovascular diseases associated to DD. Istaroxime has the dual properties to accelerate Ca2+ uptake into sarcoplasmic reticulum (SR) through the SR Ca2+ pump (SERCA2a) stimulation and to inhibit Na+/K+ ATPase (NKA). This project aims to characterize istaroxime effects at a concentration (100 nmol/L) marginally affecting NKA, in order to highlight its effects dependent on the stimulation of SERCA2a in an animal model of mild diabetes.
Methods and results
Streptozotocin (STZ) treated diabetic rats were studied at 9 weeks after STZ injection in comparison to controls (CTR). Istaroxime effects were evaluated in vivo and in left ventricular (LV) preparations. STZ animals showed 1) marked DD not associated to cardiac fibrosis, 2) LV mass reduction associated to reduced LV cell dimension and T-tubules loss, 3) reduced LV SERCA2 protein level and activity and 4) slower SR Ca2+ uptake rate, 5) LV action potential (AP) prolongation and increased short-term variability (STV) of AP duration, 6) increased diastolic Ca2+, and 7) unaltered SR Ca2+ content and stability in intact cells. Acute istaroxime infusion (0.11 mg/kg/min for 15 min) reduced DD in STZ rats. Accordingly, in STZ myocytes istaroxime (100 nmol/L) stimulated SERCA2a activity and blunted STZ-induced abnormalities in LV Ca2+ dynamics. In CTR myocytes, istaroxime increased diastolic Ca2+ level due to NKA blockade albeit minimal, while its effects on SERCA2a were almost absent.
Conclusions
SERCA2a stimulation by istaroxime improved STZ-induced DD and intracellular Ca2+ handling anomalies. Thus, SERCA2a stimulation can be considered a promising therapeutic approach for DD treatment.
Translational perspective
Deficient sarcoplasmic reticulum (SR) Ca2+ uptake has been identified in cardiomyocytes from failing human hearts with impaired diastolic relaxation (e.g. diabetic hearts) and has been associated with a decreased SERCA2a expression and activity and/or with a higher SERCA2a inhibition by phospholamban. Thus, SERCA2a may represent a pharmacological target for interventions aimed at improving cytosolic Ca2+ compartmentalization into the SR to limit diastolic dysfunction pathologies. In this context, istaroxime is the first-in-class luso-inotropic agent targeting SERCA2a that has already demonstrated its efficacy in clinical trials and may be useful to clarify the relevance of SERCA2a stimulation in controlling cytosolic Ca2+ level.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 31 Mar 2021; epub ahead of print

Influence of sex on intracellular calcium homeostasis in patients with atrial fibrillation.

Herraiz-Martínez A, Tarifa C, Jiménez-Sábado V, Llach A, ... Cinca J, Hove-Madsen L
Aims
Atrial fibrillation (AF) has been associated with intracellular calcium disturbances in human atrial myocytes, but little is known about the potential influence of sex and we here aimed to address this issue.
Methods and results
Alterations in calcium regulatory mechanisms were assessed in human atrial myocytes from patients without AF or with long-standing persistent or permanent AF. Patch-clamp measurements revealed that L-type calcium current (ICa) density was significantly smaller in males with than without AF (-1.15±0.37 vs. -2.06±0.29 pA/pF) but not in females with AF (-1.88±0.40 vs. -2.21±0.0.30 pA/pF). In contrast, transient inward currents (ITi) were more frequent in females with than without AF (1.92±0.36 vs. 1.10±0.19 events/min) but not in males with AF. Moreover, confocal calcium imaging showed that females with AF had more calcium spark sites than those without AF (9.8±1.8 vs. 2.2±1.9 sites/µm2) and sparks were wider (3.0±0.3 vs. 2.2±0.3 µm) and lasted longer (79±6 vs. 55±8 ms), favoring their fusion into calcium waves that triggers ITIs and afterdepolarizations. This was linked to higher ryanodine receptor phosphorylation at s2808 in women with AF, and inhibition of adenosine A2A or beta-adrenergic receptors that modulate s2808 phosphorylation was able to reduce the higher incidence of ITI in women with AF.
Conclusion
Perturbations of the calcium homeostasis in AF is sex-dependent, concurring with increased spontaneous SR calcium release-induced electrical activity in women but not in men, and with diminished ICa density in men only.
Translational perspective
Statistical analysis taking into account confounding effects of concurrent disease, risk factors and treatments revealed differential sex-dependent alterations of the calcium homeostasis in AF. The analysis suggests that suppression of calcium release-induced membrane depolarizations with adenosine receptor antagonists may be efficient in women with AF only while therapies aiming to restore L-type calcium current may be more efficient in males with AF.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 30 Mar 2021; epub ahead of print

Zebrafish scube1 and scube2 cooperate in promoting Vegfa signaling during embryonic vascularization.

Tsao KC, Lin YC, Chen YT, Lai SL, Yang RB
Aims
The secreted and membrane-anchored SCUBE (signal peptide-CUB-EGF domain-containing proteins) gene family composed of 3 members was originally identified from endothelial cells (ECs). We recently showed that membrane SCUBE2 binds vascular endothelial growth factor A (VEGFA) and acts as a co-receptor for VEGF receptor 2 (VEGFR2) to modulate EC migration, proliferation and tube formation during postnatal and tumor angiogenesis. However, whether these SCUBE genes cooperate in modulating VEGF signaling during embryonic vascular development remains unknown.
Methods and results
To further dissect the genetic interactions of these scube genes, transcription activator-like effector nuclease-mediated genome editing was used to generate knockout (KO) alleles of each scube gene. No overt vascular phenotypes were seen in any single scube KO mutants because of compensation by other scube genes during zebrafish development. However, scube1 and scube2 double KO (DKO) severely impaired EC filopodia extensions, migration, and proliferation, thus disrupting proper vascular lumen formation during vasculogenesis and angiogenesis as well as development of the organ-specific intestinal vasculature. Further genetic, biochemical, and molecular analyses revealed that Scube1 and Scube2 might act cooperatively at the cell-surface receptor level to facilitate Vegfa signaling during zebrafish embryonic vascularization.
Conclusions
We showed for the first time that cooperation between scube1 and scube2 is critical for proper regulation of angiogenic cell behaviors and formation of functional vessels during zebrafish embryonic development.
Translational perspective
Our studies indicate that targeting SCUBE1 and/or SCUBE2 on modulating VEGF signaling might provide potential therapeutic treatments or VEGF-mediated proliferative pathological vascular diseases.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 30 Mar 2021; epub ahead of print

Concurrent diabetes and heart failure: interplay and novel therapeutic approaches.

Karwi QG, Ho KL, Pherwani S, Ketema EB, Sun QY, Lopaschuk GD
Diabetes mellitus increases the risk of developing heart failure, and the co-existence of both diseases worsens cardiovascular outcomes, hospitalization and the progression of heart failure. Despite current advancements on therapeutic strategies to manage hyperglycemia, the likelihood of developing diabetes-induced heart failure is still significant, especially with the accelerating global prevalence of diabetes and an ageing population. This raises the likelihood of other contributing mechanisms beyond hyperglycemia in predisposing diabetic patients to cardiovascular disease risk. There has been considerable interest in understanding the alterations in cardiac structure and function in the diabetic patients, collectively termed as \"diabetic cardiomyopathy\". However, the factors that contribute to the development of diabetic cardiomyopathies is not fully understood. This review summarizes the main characteristics of diabetic cardiomyopathies, and the basic mechanisms that contribute to its occurrence. This includes perturbations in insulin resistance, fuel preference, reactive oxygen species generation, inflammation, cell death pathways, neurohormonal mechanisms, advanced glycated end-products accumulation, lipotoxicity, glucotoxicity, and posttranslational modifications in the heart of the diabetic. This review also discusses the impact of antihyperglycemic therapies on the development of heart failure, as well as how current heart failure therapies influence glycemic control in diabetic patients. We also highlight the current knowledge gaps in understanding how diabetes induces heart failure.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 29 Mar 2021; epub ahead of print

Rituximab in Patients with Acute ST-elevation Myocardial Infarction (RITA-MI): an Experimental Medicine Safety Study.

Zhao TX, Ur-Rahman MA, Sage AP, Victor S, ... Hoole SP, Mallat Z
Aims
In pre-clinical models of acute myocardial infarction (MI), mature B cells mobilise inflammatory monocytes into the heart, leading to increased infarct size and deterioration of cardiac function, whilst anti-CD20 antibody mediated depletion of B cells limits myocardial injury and improves cardiac function. Rituximab is a monoclonal anti-CD20 antibody targeted against human B cells. However, its use in cardiovascular disease is untested and is currently contraindicated. Therefore, we assessed the safety, feasibility and pharmacodynamic effect of rituximab given to patients with acute ST elevation MI (STEMI).
Methods and results
RITA-MI was a prospective, open-label, dose-escalation, single-arm, phase 1/2a clinical trial, which tested rituximab administered as a single intravenous dose in patients with STEMI within 48 hours of symptom onset. Four escalating doses (200, 500, 700 and 1000 mg) were used. The primary endpoint was safety, whilst secondary endpoints were changes in circulating immune cell subsets including B cells, and cardiac and inflammatory biomarkers. [NCT : 03072199]. A total of 24 patients were dosed. Rituximab appeared well tolerated. Seven serious adverse events were reported, none of which were assessed as being related to the rituximab infusion. Rituximab caused a mean 96.3% (95% CI 93.8-98.8%) depletion of circulating B cells within 30 mins of starting the infusion. Maximal B cell depletion was seen at day 6, which was significantly lower than baseline for all doses (p < 0.001). B cell repopulation at 6 months was dose-dependent, with modulation of returning B cell subsets. Immunoglobulin (IgG, IgM and IgA) levels were not affected during the 6 months of follow-up.
Conclusions
A single infusion of rituximab appears safe when given in the acute STEMI setting and substantially alters circulating B cell subsets. We provide important new insight into the feasibility and pharmacodynamics of rituximab in acute STEMI, which will inform further clinical translation of this potential therapy.
Clinical trial registration
NCT03072199 at https://www.clinicaltrials.gov/.
Translational perspective
Selective depletion of B cells using anti-CD20 antibody has been shown to be beneficial in various pre-clinical models of myocardial infarction with additional supportive clinical observational data. Our research provides the first translational step in using this strategy in patients. We found rituximab to be safe and effective in rapidly and profoundly depleting B cells in patients after an acute myocardial infarction. This work has directly led to the funding and setup of a multi-centre, international, randomised, double-blind, placebo-controlled, phase 2 b clinical trial which should give us an indication of this strategy\'s clinical efficacy.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 29 Mar 2021; epub ahead of print

The subfornical organ drives hypertension in polycystic kidney disease via the hypothalamic paraventricular nucleus.

Underwood CF, Mcmullan S, Goodchild AK, Phillips JK, Hildreth CM
Aims
Hypertension is a prevalent yet poorly understood feature of polycystic kidney disease. Previously we demonstrated that increased glutamatergic neurotransmission within the hypothalamic paraventricular nucleus produces hypertension in the Lewis Polycystic Kidney rat model of polycystic kidney disease. Here we tested the hypothesis that augmented glutamatergic drive to the paraventricular nucleus in Lewis Polycystic Kidney rats originates from the forebrain lamina terminalis, a sensory structure that relays blood-borne information throughout the brain.
Methods and results
Anatomical experiments revealed that 38% of paraventricular nucleus-projecting neurons in the subfornical organ of the lamina terminalis expressed Fos/Fra, an activation marker, in Lewis Polycystic Kidney rats while <1% of neurons were Fos/Fra+ in Lewis control rats (P = 0.01, n = 8). In anaesthetised rats, subfornical organ neuronal inhibition using isoguvacine produced a greater reduction in systolic blood pressure in the Lewis Polycystic Kidney versus Lewis rats (-21 ± 4 vs. -7 ± 2 mmHg, P < 0.01; n = 10), which could be prevented by prior blockade of paraventricular nucleus ionotropic glutamate receptors using kynurenic acid. Blockade of ionotropic glutamate receptors in the paraventricular nucleus produced an exaggerated depressor response in Lewis Polycystic Kidney relative to Lewis rats (-23 ± 4 vs. -2 ± 3 mmHg, P < 0.001; n = 13), which was corrected by prior inhibition of the subfornical organ with muscimol but unaffected by chronic systemic angiotensin II type I receptor antagonism or lowering of plasma hyperosmolality through high-water intake (P > 0.05); treatments that both nevertheless lowered blood pressure in Lewis Polycystic Kidney rats (P < 0.0001).
Conclusion
Our data reveal multiple independent mechanisms contribute to hypertension in polycystic kidney disease, and identify high plasma osmolality, angiotensin II type I receptor activation and, importantly, a hyperactive subfornical organ to paraventricular nucleus glutamatergic pathway as potential therapeutic targets.
Translational perspective
Hypertension is a significant comorbidity for all forms of chronic kidney disease and for individuals with polycystic kidney disease, often an early presenting feature. Nevertheless, the cause(s) of hypertension in polycystic kidney disease are poorly defined. Here we define the contribution of a neural pathway that contributes to hypertension in polycystic kidney disease. Critically, targeting this pathway may provide an additional antihypertensive effect beyond that achieved with current conventional antihypertensive therapies. Future work identifying the drivers of this neural pathway will aid in the development of newer generation antihypertensive medication.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 27 Mar 2021; epub ahead of print

Why translation from basic discoveries to clinical applications is so difficult for atrial fibrillation and possible approaches to improving it.

Nattel S, Sager P, Huser J, Heijman J, Dobrev D
Atrial fibrillation (AF) is the most common sustained clinical arrhythmia, with a lifetime incidence of up to 37%, and is a major contributor to population morbidity and mortality. Important components of AF management include control of cardiac rhythm, rate and thromboembolic risk. In this narrative review article, we focus on rhythm control therapy. The available therapies for cardiac rhythm control include antiarrhythmic drugs and catheter-based ablation procedures; both of these are presently neither optimally effective nor safe. In order to develop improved treatment options it is necessary to use preclinical models, both to identify novel mechanism-based therapeutic targets and to test the effects of putative therapies before initiating clinical trials. Extensive research over the past 30 years has provided many insights into AF mechanisms that can be used to design new rhythm-maintenance approaches. However, it has proven very difficult to translate these mechanistic discoveries into clinically applicable safe and effective new therapies. The aim of the present paper is to explore the challenges that underlie this phenomenon. We begin by considering the basic problem of AF, including its clinical importance, the current therapeutic landscape, the drug development pipeline, and the notion of upstream therapy. We then discuss the currently available preclinical models of AF and their limitations, and move on to regulatory hurdles and considerations and then review industry concerns and strategies. Finally, we evaluate potential paths forward, attempting to derive insights from the developmental history of currently used approaches and suggesting possible paths for the future. While the introduction of successful conceptually innovative new treatments for AF control is proving extremely difficult, one significant breakthrough is likely to revolutionize both AF management and the therapeutic development landscape.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 24 Mar 2021; epub ahead of print

Treatment and prevention of lipoprotein(a)-mediated cardiovascular disease: the emerging potential of RNA interference therapeutics.

Swerdlow DI, Rider DA, Yavari A, Lindholm MW, Campion GV, Nissen SE
Lipid- and lipoprotein-modifying therapies have expanded substantially in the last 25 years, resulting in reduction in the incidence of major adverse cardiovascular events. However, no specific lipoprotein (a) Lp(a)]-targeting therapy has yet been shown to reduce cardiovascular disease risk. Many epidemiological and genetic studies have demonstrated that lipoprotein(a) is an important genetically-determined causal risk factor for coronary heart disease, aortic valve disease, stroke, heart failure and peripheral vascular disease. Accordingly, the need for specific lipoprotein(a)-lowering therapy has become a major public health priority. Approximately 20% of the global population (1.4 billion people) have elevated levels of Lp(a) associated with higher cardiovascular risk, though the threshold for determining \'high risk\' is debated. Traditional lifestyle approaches to cardiovascular risk reduction are ineffective at lowering Lp(a). To address a lifelong risk factor unmodifiable by non-pharmacological means, Lp(a)-lowering therapy needs to be safe, highly effective, and tolerable for a patient population who will likely require several decades of treatment. N-acetylgalactosamine (GalNAc)-conjugated gene silencing therapeutics such as small interfering RNA (siRNA) and antisense oligonucleotide targeting LPA are ideally suited for this application, offering a highly tissue- and target transcript-specific approach with the potential for safe and durable lipoprotein(a) lowering with as few as three or four doses per year. In this review, we evaluate the causal role of lipoprotein(a) across the cardiovascular disease spectrum, examine the role of established lipid modifying therapies in lowering lipoprotein(a), and focus on the anticipated role for siRNA therapeutics in treating and preventing lipoprotein(a)-related disease.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 24 Mar 2021; epub ahead of print

Gut microbiota dysbiosis promotes age-related atrial fibrillation by lipopolysaccharide and glucose-induced activation of NLRP3-inflammasome.

Zhang Y, Zhang S, Li B, Luo Y, ... Wu Y, Li Y
Aims
Aging is the most significant contributor to the increasing prevalence of atrial fibrillation (AF). The gut microbiota dysbiosis is involved in age-related diseases. However, whether the aged-associated dysbiosis contributes to age-related AF is still unknown. Direct demonstration that the aged gut microbiota is sufficient to transmit the enhanced AF susceptibility in a young host via microbiota-intestinal barrier-atria axis has not yet been reported. This study aimed to determine whether gut microbiota dysbiosis affects age-related AF.
Methods and results
Herein, by using a fecal microbiota transplantation (FMT) rat model, we demonstrated that the high AF susceptibility of aged rats could be transmitted to a young host. Specially, we found the dramatically increased levels of circulating lipopolysaccharide (LPS) and glucose led to the up-regulated expression of NLR family pyrin domain containing 3 (NLRP3)-inflammasome, promoting the development of AF which depended on the enhanced atrial fibrosis in recipient host. Inhibition of inflammasome by a potent and selective inhibitor of the NLRP3 inflammasome, MCC950, resulted in a lower atrial fibrosis and AF susceptibility. Then we conducted cross-sectional clinical studies to explore the effect of aging on the altering trends with glucose levels and circulating LPS among clinical individuals in two China hospitals. We found that both of serum LPS and glucose levels were progressively increased in elderly patients as compared with those young. Furthermore, the aging phenotype of circulating LPS and glucose levels, intestinal structure and atrial NLRP3-inflammasome of rats were also confirmed in clinical AF patients. Finally, aged rats colonized with youthful microbiota restored intestinal structure and atrial NLRP3-inflammasome activity, which suppressed the development of aged-related AF.
Conclusions
Collectively, these studies described a novel causal role of aberrant gut microbiota in the pathogenesis of age-related AF, which indicates that the microbiota-intestinal barrier-atrial NLRP3 inflammasome axis may be a rational molecular target for the treatment of aged-related arrhythmia disease.
Translational perspective
The current study demonstrates that aged-associated microbiota dysbiosis promotes AF in part through a microbiota-gut-atria axis. Increased AF susceptibility due to enhanced atrial NLRP3-inflammasome activity by LPS and high glucose was found in an aged FMT rat model, and also confirmed within elderly clinical individuals. In a long-term FMT rat study, the AF susceptibility was ameliorated by treatment with youthful microbiota. The present findings can further increase our understanding of aged-related AF and address a promising therapeutic strategy that involves modulation of gut microbiota composition.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 22 Mar 2021; epub ahead of print

SPARC-related modular calcium binding 1 regulates aortic valve calcification by disrupting BMPR-II/p-p38 signalling.

Wang Y, Gu J, Du A, Zhang S, ... Sun W, Kong X
Aims
Aortic valve calcification is more prevalent in chronic kidney disease accompanied by hypercalcemia. SPARC (Secreted Protein Acidic and Rich in Cysteine)-related modular calcium binding 1 (SMOC1) is a regulator of BMP2 signalling, but the role of SMOC1 in aortic valve calcification under different conditions has not been studied. This study aimed to investigate the roles of SMOC1 in aortic valve calcification under normal and high calcium conditions, focusing on the effects on aortic valve interstitial cells (AVICs).
Methods and results
SMOC1 was expressed by aortic valve endothelial cells and secreted into the extracellular matrix in non-calcific valves and downregulated in calcific aortic valves. In vitro studies demonstrated that HUVEC secreted SMOC1 could enter the cytoplasm of AVICs. Overexpression of SMOC1 attenuated warfarin-induced AVIC calcification but promoted high calcium/phosphate or vitamin D-induced AVIC and aortic valve calcification by regulating BMP2 signalling both in vitro and in vivo. Co-immunoprecipitation revealed that SMOC1 binds to BMP receptor II (BMPR-II) and inhibits BMP2-induced phosphorylation of p38 (p-p38) via amino acids 372-383 of its EF-hand calcium-binding domain. Inhibition of p-p38 by the p38 inhibitor SB203580 blocked the effects of SMOC1 on BMP2 signalling and AVIC calcification induced by high calcium/phosphate medium. In high-calcium-treated AVICs, SMOC1 lost its ability to bind to BMPR-II, but not to caveolin-1, promoting p-p38 and cell apoptosis due to increased expression of BMPR-II and enhanced endocytosis.
Conclusions
These observations support that SMOC1 works as a dual-directional modulator of AVIC calcification by regulating p38-dependent BMP2 signalling transduction according to different extracellular calcium concentrations.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 22 Mar 2021; epub ahead of print

Dissecting the transcriptome in cardiovascular disease.

Robinson EL, Baker AH, Brittan M, McCracken I, ... Martelli F, EU-CardioRNA COST Action CA17129
The human transcriptome comprises a complex network of coding and non-coding RNAs implicated in a myriad of biological functions. Non-coding RNAs exhibit highly organised spatial and temporal expression patterns and are emerging as critical regulators of differentiation, homeostasis and pathological states, including in the cardiovascular system. This review defines the current knowledge gaps, unmet methodological needs and describes the challenges in dissecting and understanding the role and regulation of the non-coding transcriptome in cardiovascular disease. These challenges include poor annotation of the non-coding genome, determination of the cellular distribution of transcripts, assessment of the role of RNA processing and identification of cell-type specific changes in cardiovascular physiology and disease. We highlight similarities and differences in the hurdles associated with the analysis of the non-coding and protein-coding transcriptomes. In addition, we discuss how the lack of consensus and absence of standardised methods affect reproducibility of data. These shortcomings should be defeated in order to make significant scientific progress and foster the development of clinically applicable non-coding RNA-based therapeutic strategies to lessen the burden of cardiovascular disease.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 22 Mar 2021; epub ahead of print

Anxa1 in smooth muscle cells protects against acute aortic dissection.

Zhou C, Lin Z, Cao H, Chen Y, ... Pan B, Zheng L
Aims
Acute aortic dissection (AAD) is a life-threatening disease with high morbidity and mortality. Previous studies have showed that vascular smooth muscle cell (VSMC) phenotype switching modulates vascular function and AAD progression. However, whether an endogenous signaling system that protects AAD progression exists, remains unknown. Our aim is to investigate the role of Anxa1 in VSMC phenotype switching and the pathogenesis of AAD.
Methods and results
We first assessed Anxa1 expression levels by immunohistochemical staining in control aorta and AAD tissue from mice. A strong increase of Anxa1 expression was seen in the mouse AAD tissues. In line with these findings, micro-CT scan results indicated that Anxa1 plays a role in the development of AAD in our murine model, with systemic deficiency of Anxa1 markedly progressing AAD. Conversely, administration of Anxa1 mimetic peptide, Ac2-26, rescued the AAD phenotype in Anxa1-/- mice. Transcriptomic studies revealed a novel role for Anxa1 in VSMC phenotype switching, with Anxa1 deficiency triggering the synthetic phenotype of VSMCs via down-regulation of the JunB/MYL9 pathway. The resultant VSMC synthetic phenotype rendered elevated inflammation and enhanced matrix metalloproteinases (MMPs) production, leading to augmented elastin degradation. VSMC-restricted deficiency of Anxa1 in mice phenocopied VSMC phenotype switching and the consequent exacerbation of AAD. Finally, our studies in human AAD aortic specimens recapitulated key findings in murine AAD, specifically that the decrease of Anxa1 is associated with VSMC phenotype switch, heightened inflammation, and enhanced MMP production in human aortas.
Conclusions
Our findings demonstrated that Anxa1 is a novel endogenous defender that prevents acute aortic dissection by inhibiting vascular smooth muscle cell phenotype switching, suggesting that Anxa1 signaling may be a potential target for AAD pharmacological therapy.
Translational perspective
Our studies herein may lead to a paradigm shift for pharmacologic therapy towards acute aortic dissection. Through careful examination of the pathological changes that occur during AAD onset in experimental animal models, we demonstrated that VSMC phenotype switching plays a critical role in the development of AAD. Inhibition of VSMC phenotype switching and its attendant impacts on aortic function may be a viable approach for future treatment. Toward that end, our studies highlighted the protective benefit of Anxa1 and its mimetic peptide Ac2-26 in AAD through prevention of the switching of VSMC to a synthetic phenotype.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 22 Mar 2021; epub ahead of print

The chemokine CXCL14 mediates platelet function and migration via direct interaction with CXCR4.

Witte A, Rohlfing AK, Dannenmann B, Dicenta V, ... Skokowa J, Gawaz M
Aims 
Beyond classical roles in thrombosis and haemostasis, it becomes increasingly clear that platelets contribute as key players to inflammatory processes. The involvement of platelets in these processes is often mediated through a variety of platelet-derived chemokines which are released upon activation and act as paracrine and autocrine factors. In this study, we investigate CXCL14, a newly described platelet chemokine and its role in thrombus formation as well as monocyte and platelet migration. In addition, we examine the chemokine receptor CXCR4 as a possible receptor for CXCL14 on platelets. Furthermore, with the use of artificially generated platelets derived from induced pluripotent stem cells (iPSC), we investigate the importance of CXCR4 for CXCL14-mediated platelet functions.
Methods and results 
In this study, we showed that CXCL14 deficient platelets reveal reduced thrombus formation under flow compared with wild-type platelets using a standardized flow chamber. Addition of recombinant CXCL14 normalized platelet-dependent thrombus formation on collagen. Furthermore, we found that CXCL14 is a chemoattractant for platelets and mediates migration via CXCR4. CXCL14 promotes platelet migration of platelets through the receptor CXCR4 as evidenced by murine CXCR4-deficient platelets and human iPSC-derived cultured platelets deficient in CXCR4. We found that CXCL14 directly interacts with the CXCR4 as verified by immunoprecipitation and confocal microscopy.
Conclusions 
Our results reveal CXCL14 as a novel platelet-derived chemokine that is involved in thrombus formation and platelet migration. Furthermore, we identified CXCR4 as principal receptor for CXCL14, an interaction promoting platelet migration.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Mar 2021; 117:903-917

Follicular regulatory helper T cells control the response of regulatory B cells to a high-cholesterol diet.

Burger F, Miteva K, Baptista D, Roth A, ... Mach F, Brandt KJ
Aims
B cell functions in the process of atherogenesis have been investigated but several aspects remain to be clarified.
Methods and results
In this study, we show that follicular regulatory helper T cells (TFR) control regulatory B cell (BREG) populations in Apoe-/- mice models on a high-cholesterol diet (HCD). Feeding mice with HCD resulted in up-regulation of TFR and BREG cell populations, causing the suppression of proatherogenic follicular helper T cell (TFH) response. TFH cell modulation is correlated with the growth of atherosclerotic plaque size in thoracoabdominal aortas and aortic root plaques, suggesting that TFR cells are atheroprotective. During adoptive transfer experiments, TFR cells transferred into HCD mice decreased TFH cell populations, atherosclerotic plaque size, while BREG cell population and lymphangiogenesis are significantly increased.
Conclusion
Our results demonstrate that, through different strategies, both TFR and TFH cells modulate anti- and pro-atherosclerotic immune processes in an Apoe-/- mice model since TFR cells are able to regulate both TFH and BREG cell populations as well as lymphangiogenesis and lipoprotein metabolism.

© The Author(s) 2020. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 21 Mar 2021; 117:743-755

Circulating uromodulin inhibits vascular calcification by interfering with pro-inflammatory cytokine signalling.

Alesutan I, Luong TTD, Schelski N, Masyout J, ... Scherberich J, Voelkl J
Aims
Uromodulin is produced exclusively in the kidney and secreted into both urine and blood. Serum levels of uromodulin are correlated with kidney function and reduced in chronic kidney disease (CKD) patients, but physiological functions of serum uromodulin are still elusive. This study investigated the role of uromodulin in medial vascular calcification, a key factor associated with cardiovascular events and mortality in CKD patients.
Methods and results 
Experiments were performed in primary human (HAoSMCs) and mouse (MOVAS) aortic smooth muscle cells, cholecalciferol overload and subtotal nephrectomy mouse models and serum from CKD patients. In three independent cohorts of CKD patients, serum uromodulin concentrations were inversely correlated with serum calcification propensity. Uromodulin supplementation reduced phosphate-induced osteo-/chondrogenic transdifferentiation and calcification of HAoSMCs. In human serum, pro-inflammatory cytokines tumour necrosis factor α (TNFα) and interleukin-1β (IL-1β) co-immunoprecipitated with uromodulin. Uromodulin inhibited TNFα and IL-1β-induced osteo-/chondrogenic signalling and activation of the transcription factor nuclear factor kappa-light-chain-enhancer of activated β cells (NF-kB) as well as phosphate-induced NF-kB-dependent transcriptional activity in HAoSMCs. In vivo, adeno-associated virus (AAV)-mediated overexpression of uromodulin ameliorated vascular calcification in mice with cholecalciferol overload. Conversely, cholecalciferol overload-induced vascular calcification was aggravated in uromodulin-deficient mice. In contrast, uromodulin overexpression failed to reduce vascular calcification during renal failure in mice. Carbamylated uromodulin was detected in serum of CKD patients and uromodulin carbamylation inhibited its anti-calcific properties in vitro.
Conclusions 
Uromodulin counteracts vascular osteo-/chondrogenic transdifferentiation and calcification, at least in part, through interference with cytokine-dependent pro-calcific signalling. In CKD, reduction and carbamylation of uromodulin may contribute to vascular pathology.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Mar 2021; 117:930-941

Zinc ameliorates human aortic valve calcification through GPR39 mediated ERK1/2 signalling pathway.

Chen Z, Gordillo-Martinez F, Jiang L, He P, ... Fu X, Zhu D
Aims
Calcific aortic valve disease (CAVD) is the most common heart valve disease in the Western world. It has been reported that zinc is accumulated in calcified human aortic valves. However, whether zinc directly regulates CAVD is yet to be elucidated. The present study sought to determine the potential role of zinc in the pathogenesis of CAVD.
Methods and results
Using a combination of a human valve interstitial cell (hVIC) calcification model, human aortic valve tissues, and blood samples, we report that 20 μM zinc supplementation attenuates hVIC in vitro calcification, and that this is mediated through inhibition of apoptosis and osteogenic differentiation via the zinc-sensing receptor GPR39-dependent ERK1/2 signalling pathway. Furthermore, we report that GPR39 protein expression is dramatically reduced in calcified human aortic valves, and there is a significant reduction in zinc serum levels in patients with CAVD. Moreover, we reveal that 20 μM zinc treatment prevents the reduction of GPR39 observed in calcified hVICs. We also show that the zinc transporter ZIP13 and ZIP14 are significantly increased in hVICs in response to zinc treatment. Knockdown of ZIP13 or ZIP14 significantly inhibited hVIC in vitro calcification and osteogenic differentiation.
Conclusions
Together, these findings suggest that zinc is a novel inhibitor of CAVD, and report that zinc transporter ZIP13 and ZIP14 are important regulators of hVIC in vitro calcification and osteogenic differentiation. Zinc supplementation may offer a potential therapeutic strategy for CAVD.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Mar 2021; 117:820-835

Efficacy and safety of rivaroxaban plus aspirin in women and men with chronic coronary or peripheral artery disease.

Liang Y, Zhu J, Liu L, Anand SS, ... Eikelboom JW, COMPASS Investigators
Aims
The COMPASS trial demonstrated that the combination of rivaroxaban 2.5 mg twice daily and aspirin 100 mg once daily compared with aspirin 100 mg once daily reduced major adverse cardiovascular events (MACE) in patients with chronic coronary artery disease or peripheral artery disease by 24% during a mean follow-up of 23 months. We explored whether this effect varies by sex.
Methods and results
The effects were examined in women and men using log-rank tests and Kaplan-Meier curve. Hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) were obtained from stratified Cox proportional hazards models to explore subgroup effects including subgroup of women and men according to baseline modified REACH risk score. Of 27 395 patients randomized, 18 278 were allocated to receive rivaroxaban plus aspirin (n = 9152) or aspirin alone (n = 9126), and of these, 22.1% were women. Women compared with men had similar incidence rates for MACE and major bleeding but borderline lower rates for myocardial infarction (1.7% vs. 2.2%, P = 0.05). The effect of combination therapy compared with aspirin in women and men was consistent for MACE (women: 3.8% vs. 5.2%, HR 0.72, 95% CI 0.54-0.97; men: 4.2% vs. 5.5%, HR 0.76, 95% CI 0.66-0.89; P interaction 0.75) and major bleeding (women: 3.1% vs. 1.4%, HR 2.22, 95% CI 1.42-3.46; men: 3.2% vs. 2.0%, HR 1.60, 95% CI 1.29-1.97; P interaction 0.19). There was no significant interaction between randomized treatment and baseline modified REACH score above or below the median for MACE or major bleeding.
Conclusion
In patients with stable coronary artery disease or peripheral artery disease, the combination of rivaroxaban (2.5 mg twice daily) and aspirin compared with aspirin alone appears to produce consistent benefits in women and men, independent of baseline cardiovascular risk.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Mar 2021; 117:942-949

Inhibition of xanthine oxidase in the acute phase of myocardial infarction prevents skeletal muscle abnormalities and exercise intolerance.

Nambu H, Takada S, Maekawa S, Matsumoto J, ... Sabe H, Kinugawa S
Aims
Exercise intolerance in patients with heart failure (HF) is partly attributed to skeletal muscle abnormalities. We have shown that reactive oxygen species (ROS) play a crucial role in skeletal muscle abnormalities, but the pathogenic mechanism remains unclear. Xanthine oxidase (XO) is reported to be an important mediator of ROS overproduction in ischaemic tissue. Here, we tested the hypothesis that skeletal muscle abnormalities in HF are initially caused by XO-derived ROS and are prevented by the inhibition of their production.
Methods and results
Myocardial infarction (MI) was induced in male C57BL/6J mice, which eventually led to HF, and a sham operation was performed in control mice. The time course of XO-derived ROS production in mouse skeletal muscle post-MI was first analysed. XO-derived ROS production was significantly increased in MI mice from Days 1 to 3 post-surgery (acute phase), whereas it did not differ between the MI and sham groups from 7 to 28 days (chronic phase). Second, mice were divided into three groups: sham + vehicle (Sham + Veh), MI + vehicle (MI + Veh), and MI + febuxostat (an XO inhibitor, 5 mg/kg body weight/day; MI + Feb). Febuxostat or vehicle was administered at 1 and 24 h before surgery, and once-daily on Days 1-7 post-surgery. On Day 28 post-surgery, exercise capacity and mitochondrial respiration in skeletal muscle fibres were significantly decreased in MI + Veh compared with Sham + Veh mice. An increase in damaged mitochondria in MI + Veh compared with Sham + Veh mice was also observed. The wet weight and cross-sectional area of slow muscle fibres (higher XO-derived ROS) was reduced via the down-regulation of protein synthesis-associated mTOR-p70S6K signalling in MI + Veh compared with Sham + Veh mice. These impairments were ameliorated in MI + Feb mice, in association with a reduction of XO-derived ROS production, without affecting cardiac function.
Conclusion
XO inhibition during the acute phase post-MI can prevent skeletal muscle abnormalities and exercise intolerance in mice with HF.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Mar 2021; 117:805-819

Loss of autophagy protein ATG5 impairs cardiac capacity in mice and humans through diminishing mitochondrial abundance and disrupting Ca2+ cycling.

Ljubojević-Holzer S, Kraler S, Djalinac N, Abdellatif M, ... Maack C, Sedej S
Aims
Autophagy protects against the development of cardiac hypertrophy and failure. While aberrant Ca2+ handling promotes myocardial remodelling and contributes to contractile dysfunction, the role of autophagy in maintaining Ca2+ homeostasis remains elusive. Here, we examined whether Atg5 deficiency-mediated autophagy promotes early changes in subcellular Ca2+ handling in ventricular cardiomyocytes, and whether those alterations associate with compromised cardiac reserve capacity, which commonly precedes the onset of heart failure.
Methods and results
RT-qPCR and immunoblotting demonstrated reduced Atg5 gene and protein expression and decreased abundancy of autophagy markers in hypertrophied and failing human hearts. The function of ATG5 was examined using cardiomyocyte-specific Atg5-knockout mice (Atg5-/-). Before manifesting cardiac dysfunction, Atg5-/- mice showed compromised cardiac reserve in response to β-adrenergic stimulation. Consequently, effort intolerance and maximal oxygen consumption were reduced during treadmill-based exercise tolerance testing. Mechanistically, cellular imaging revealed that Atg5 deprivation did not alter spatial and functional organization of intracellular Ca2+ stores or affect Ca2+ cycling in response to slow pacing or upon acute isoprenaline administration. However, high frequency stimulation exposed stunted amplitude of Ca2+ transients, augmented nucleoplasmic Ca2+ load and increased CaMKII activity, especially in the nuclear region of hypertrophied Atg5-/- cardiomyocytes. These changes in Ca2+ cycling were recapitulated in hypertrophied human cardiomyocytes. Finally, ultrastructural analysis revealed accumulation of mitochondria with reduced volume and size distribution, meanwhile functional measurements showed impaired redox balance in Atg5-/- cardiomyocytes, implying energetic unsustainability due to overcompensation of single mitochondria, particularly under increased workload.
Conclusion
Loss of cardiac Atg5-dependent autophagy reduces mitochondrial abundance and causes subtle alterations in subcellular Ca2+ cycling upon increased workload in mice. Autophagy-related impairment of Ca2+ handling is progressively worsened by β-adrenergic signalling in ventricular cardiomyocytes, thereby leading to energetic exhaustion and compromised cardiac reserve.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 21 Mar 2021; epub ahead of print

Myocardin-related transcription factor A (MRTF-A) regulates integrin beta 2 transcription to promote macrophage infiltration and cardiac hypertrophy in mice.

Liu L, Zhao Q, Kong M, Mao L, Yang Y, Xu Y
Aims
Macrophage-mediated inflammatory response represents a key pathophysiological process in a host of cardiovascular diseases including heart failure. Regardless of etiology, heart failure is invariably preceded by cardiac hypertrophy. In the present study we investigated the effect of macrophage-specific deletion of myocardin-related transcription factor A (MRTF-A) on cardiac hypertrophy and the underlying mechanism.
Methods and results
We report that when subjected to transverse aortic constriction (TAC), macrophage MRTF-A conditional knockout (CKO) mice developed a less severe phenotype of cardiac hypertrophy compared to wild type (WT) littermates and were partially protected from the loss of heart function. In addition, there was less extensive cardiac fibrosis in the CKO mice than WT mice following the TAC procedure. Further analysis revealed that cardiac inflammation, as assessed by levels of pro-inflammatory cytokines and chemokines, was dampened in CKO mice paralleling reduced infiltration of macrophages in the heart. Mechanistically, MRTF-A deficiency attenuated the expression of integrin beta 2 (ITGB2/CD18) in macrophage thereby disrupting adhesion of macrophages to vascular endothelial cells. MRTF-A was recruited by Sp1 to the ITGB2 promoter and cooperated with Sp1 to activate ITGB2 transcription in macrophages. Administration of a CD18 blocking antibody attenuated TAC induced cardiac hypertrophy in mice. Interaction between MRTF-A and the histone demethylase KDM3A likely contributed to IGTB2 transcription and consequently adhesion of macrophages to endothelial cells.
Conclusions
Our data suggest that MRTF-A may regulate macrophage trafficking and contribute to the pathogenesis of cardiac hypertrophy by activating ITGB2 transcription.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 21 Mar 2021; epub ahead of print

Free fatty acid receptor 4 responds to endogenous fatty acids to protect the heart from pressure overload.

Murphy KA, Harsch BA, Healy CL, Joshi SS, ... Shearer GC, O\'Connell TD
Aims
Free fatty acid receptor 4 (Ffar4) is a G-protein coupled receptor for endogenous medium/long-chain fatty acids that attenuates metabolic disease and inflammation. However, the function of Ffar4 in the heart is unclear. Given its putative beneficial role, we hypothesized that Ffar4 would protect the heart from pathologic stress.
Methods and results
In mice lacking Ffar4 (Ffar4KO), we found that Ffar4 is required for an adaptive response to pressure overload induced by transverse aortic constriction (TAC), identifying a novel cardioprotective function for Ffar4. Following TAC, remodeling was worsened in Ffar4KO hearts, with greater hypertrophy and contractile dysfunction. Transcriptome analysis 3-days post-TAC identified transcriptional deficits in genes associated with cytoplasmic phospholipase A2α signaling and oxylipin synthesis as well as reduction of oxidative stress in Ffar4KO myocytes. In cultured adult cardiac myocytes, Ffar4 induced production of the eicosapentaenoic acid (EPA)-derived, pro-resolving oxylipin 18-hydroxyeicosapentaenoic acid (18-HEPE). Furthermore, activation of Ffar4 attenuated cardiac myocyte death from oxidative stress, while 18-HEPE rescued Ffar4KO myocytes. Systemically, Ffar4 maintained pro-resolving oxylipins and attenuated autoxidation basally, and increased pro-inflammatory and pro-resolving oxylipins, including 18-HEPE, in high density lipoproteins post-TAC. In humans, Ffar4 expression decreased in heart failure, while the signaling-deficient Ffar4 R270H polymorphism correlated with eccentric remodeling in a large clinical cohort paralleling changes observed in Ffar4KO mice post-TAC.
Conclusions
Our data indicate that Ffar4 in cardiac myocytes responds to endogenous fatty acids, reducing oxidative injury, and protecting the heart from pathologic stress, with significant translational implications for targeting Ffar4 in cardiovascular disease.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 21 Mar 2021; epub ahead of print

Deletion of fibroblast activation protein provides atheroprotection.

Stein S, Weber J, Nusser-Stein S, Pahla J, ... Lüscher TF, Matter CM
Aims
Fibroblast activation protein (FAP) is upregulated at sites of tissue remodelling including chronic arthritis, solid tumours, and fibrotic hearts. It has also been associated with human coronary atherosclerotic plaques. Yet, the causal role of FAP in atherosclerosis remains unknown. To investigate the cause-effect relationship of endogenous FAP in atherogenesis, we assessed the effects of constitutive Fap deletion on plaque formation in atherosclerosis-prone apolipoprotein E (Apoe) or low-density lipoprotein receptor (Ldlr) knockout mice.
Methods and results
Using en face analyses of thoraco-abdominal aortae and aortic sinus cross-sections, we demonstrate that Fap deficiency decreased plaque formation in two atherosclerotic mouse models (-46% in Apoe and -34% in Ldlr knockout mice). As a surrogate of plaque vulnerability fibrous cap thickness was used; it was increased in Fap-deficient mice, whereas Sirius red staining demonstrated that total collagen content remained unchanged. Using polarized light, atherosclerotic lesions from Fap-deficient mice displayed increased FAP targets in terms of enhanced collagen birefringence in plaques and increased pre-COL3A1 expression in aortic lysates. Analyses of the Stockholm Atherosclerosis Gene Expression data revealed that FAP expression was increased in human atherosclerotic compared to non-atherosclerotic arteries.
Conclusions
Our data provide causal evidence that constitutive Fap deletion decreases progression of experimental atherosclerosis and increases features of plaque stability with decreased collagen breakdown. Thus, inhibition of FAP expression or activity may not only represent a promising therapeutic target in atherosclerosis but appears safe at the experimental level for FAP-targeted cancer therapies.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]m.

Cardiovasc Res: 20 Mar 2021; 117:1060-1069

Ketones can become the major fuel source for the heart but do not increase cardiac efficiency.

Ho KL, Karwi QG, Wagg C, Zhang L, ... Ussher JR, Lopaschuk GD
Aims
Ketones have been proposed to be a \'thrifty\' fuel for the heart and increasing cardiac ketone oxidation can be cardioprotective. However, it is unclear how much ketone oxidation can contribute to energy production in the heart, nor whether increasing ketone oxidation increases cardiac efficiency. Therefore, our goal was to determine to what extent high levels of the ketone body, β-hydroxybutyrate (βOHB), contributes to cardiac energy production, and whether this influences cardiac efficiency.
Methods and results
Isolated working mice hearts were aerobically perfused with palmitate (0.8 mM or 1.2 mM), glucose (5 mM) and increasing concentrations of βOHB (0, 0.6, 2.0 mM). Subsequently, oxidation of these substrates, cardiac function, and cardiac efficiency were assessed. Increasing βOHB concentrations increased myocardial ketone oxidation rates without affecting glucose or fatty acid oxidation rates where normal physiological levels of glucose (5 mM) and fatty acid (0.8 mM) are present. Notably, ketones became the major fuel source for the heart at 2.0 mM βOHB (at both low or high fatty acid concentrations), with the elevated ketone oxidation rates markedly increasing tricarboxylic acid (TCA) cycle activity, producing a large amount of reducing equivalents and finally, increasing myocardial oxygen consumption. However, the marked increase in ketone oxidation at high concentrations of βOHB was not accompanied by an increase in cardiac work, suggesting that a mismatch between excess reduced equivalents production from ketone oxidation and cardiac adenosine triphosphate production. Consequently, cardiac efficiency decreased when the heart was exposed to higher ketone levels.
Conclusions
We demonstrate that while ketones can become the major fuel source for the heart, they do not increase cardiac efficiency, which also underscores the importance of recognizing ketones as a major fuel source for the heart in times of starvation, consumption of a ketogenic diet or poorly controlled diabetes.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 20 Mar 2021; 117:1178-1187

Ventricular fibrillation mechanism and global fibrillatory organization are determined by gap junction coupling and fibrosis pattern.

Handa BS, Li X, Baxan N, Roney CH, ... Peters NS, Ng FS
Aims
Conflicting data exist supporting differing mechanisms for sustaining ventricular fibrillation (VF), ranging from disorganized multiple-wavelet activation to organized rotational activities (RAs). Abnormal gap junction (GJ) coupling and fibrosis are important in initiation and maintenance of VF. We investigated whether differing ventricular fibrosis patterns and the degree of GJ coupling affected the underlying VF mechanism.
Methods and results
Optical mapping of 65 Langendorff-perfused rat hearts was performed to study VF mechanisms in control hearts with acute GJ modulation, and separately in three differing chronic ventricular fibrosis models; compact fibrosis (CF), diffuse fibrosis (DiF), and patchy fibrosis (PF). VF dynamics were quantified with phase mapping and frequency dominance index (FDI) analysis, a power ratio of the highest amplitude dominant frequency in the cardiac frequency spectrum. Enhanced GJ coupling with rotigaptide (n = 10) progressively organized fibrillation in a concentration-dependent manner; increasing FDI (0 nM: 0.53 ± 0.04, 80 nM: 0.78 ± 0.03, P < 0.001), increasing RA-sustained VF time (0 nM: 44 ± 6%, 80 nM: 94 ± 2%, P < 0.001), and stabilized RAs (maximum rotations for an RA; 0 nM: 5.4 ± 0.5, 80 nM: 48.2 ± 12.3, P < 0.001). GJ uncoupling with carbenoxolone progressively disorganized VF; the FDI decreased (0 µM: 0.60 ± 0.05, 50 µM: 0.17 ± 0.03, P < 0.001) and RA-sustained VF time decreased (0 µM: 61 ± 9%, 50 µM: 3 ± 2%, P < 0.001). In CF, VF activity was disorganized and the RA-sustained VF time was the lowest (CF: 27 ± 7% vs. PF: 75 ± 5%, P < 0.001). Global fibrillatory organization measured by FDI was highest in PF (PF: 0.67 ± 0.05 vs. CF: 0.33 ± 0.03, P < 0.001). PF harboured the longest duration and most spatially stable RAs (patchy: 1411 ± 266 ms vs. compact: 354 ± 38 ms, P < 0.001). DiF (n = 11) exhibited an intermediately organized VF pattern, sustained by a combination of multiple-wavelets and short-lived RAs.
Conclusion
The degree of GJ coupling and pattern of fibrosis influences the mechanism sustaining VF. There is a continuous spectrum of organization in VF, ranging between globally organized fibrillation sustained by stable RAs and disorganized, possibly multiple-wavelet driven fibrillation with no RAs.

© The Author(s) 2020. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 20 Mar 2021; 117:1078-1090

Dilated cardiomyopathy-linked heat shock protein family D member 1 mutations cause up-regulation of reactive oxygen species and autophagy through mitochondrial dysfunction.

Enomoto H, Mittal N, Inomata T, Arimura T, ... Fukuda K, Makino S
Aims
During heart failure, the levels of circulatory heat shock protein family D member 1 (HSP60) increase. However, its underlying mechanism is still unknown. The apical domain of heat shock protein family D member 1 (HSPD1) is conserved throughout evolution. We found a point mutation in HSPD1 in a familial dilated cardiomyopathy (DCM) patient. A similar point mutation in HSPD1 in the zebrafish mutant, nbl, led to loss of its regenerative capacity and development of pericardial oedema under heat stress condition. In this study, we aimed to determine the direct involvement of HSPD1 in the development of DCM.
Methods and results
By Sanger method, we found a point mutation (Thr320Ala) in the apical domain of HSPD1, in one familial DCM patient, which was four amino acids away from the point mutation (Val324Glu) in the nbl mutant zebrafish. The nbl mutants showed atrio-ventricular block and sudden death at 8-month post-fertilization. Histological and microscopic analysis of the nbl mutant hearts showed decreased ventricular wall thickness, elevated level of reactive oxygen species (ROS), increased fibrosis, mitochondrial damage, and increased autophagosomes. mRNA and protein expression of autophagy-related genes significantly increased in nbl mutants. We established HEK293 stable cell lines of wild-type, nbl-type, and DCM-type HSPD1, with tetracycline-dependent expression. Compared to wild-type, both nbl- and DCM-type cells showed decreased cell growth, increased expression of ROS and autophagy-related genes, inhibition of the activity of mitochondrial electron transport chain complexes III and IV, and decreased mitochondrial fission and fusion.
Conclusion
Mutations in HSPD1 caused mitochondrial dysfunction and induced mitophagy. Mitochondrial dysfunction caused increased ROS and cardiac atrophy.

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Cardiovasc Res: 20 Mar 2021; 117:1118-1131

Rare loss-of-function mutations of PTGIR are enriched in fibromuscular dysplasia.

Georges A, Albuisson J, Berrandou T, Dupré D, ... Jeunemaitre X, Bouatia-Naji N
Aims
Fibromuscular dysplasia (FMD) and spontaneous coronary artery dissection (SCAD) are related, non-atherosclerotic arterial diseases mainly affecting middle-aged women. Little is known about their physiopathological mechanisms. We aimed to identify rare genetic causes to elucidate molecular mechanisms implicated in FMD and SCAD.
Methods and results
We analysed 29 exomes that included familial and sporadic FMD. We identified one rare loss-of-function variant (LoF) (frequencygnomAD = 0.000075) shared by two FMD sisters in the prostaglandin I2 receptor gene (PTGIR), a key player in vascular remodelling. Follow-up was conducted by targeted or Sanger sequencing (1071 FMD and 363 SCAD patients) or lookups in exome (264 FMD) or genome sequences (480 SCAD), all independent and unrelated. It revealed four additional LoF allele carriers, in addition to several rare missense variants, among FMD patients, and two LoF allele carriers among SCAD patients, including one carrying a rare splicing mutation (c.768 + 1C>G). We used burden test to test for enrichment in patients compared to gnomAD controls, which detected a putative enrichment in FMD (PTRAPD = 8 × 10-4), but not a significant enrichment (PTRAPD = 0.12) in SCAD. The biological effects of variants on human prostaclycin receptor (hIP) signalling and protein expression were characterized using transient overexpression in human cells. We confirmed the LoFs (Q163X and P17RfsX6) and one missense (L67P), identified in one FMD and one SCAD patient, to severely impair hIP function in vitro.
Conclusions
Our study shows that rare genetic mutations in PTGIR are enriched among FMD patients and found in SCAD patients, suggesting a role for prostacyclin signalling in non-atherosclerotic stenosis and dissection.

© The Author(s) 2020. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 20 Mar 2021; 117:1154-1165

Stretch-induced sarcoplasmic reticulum calcium leak is causatively associated with atrial fibrillation in pressure-overloaded hearts.

Zhang Y, Qi Y, Li JJ, He WJ, ... Du XJ, Xie W
Aims
Despite numerous reports documenting an important role of hypertension in the development of atrial fibrillation (AF), the detailed mechanism underlying the pathological process remains incompletely understood. Here, we aim to test the hypothesis that diastolic sarcoplasmic reticulum (SR) Ca2+ leak in atrial myocytes, induced by mechanical stretch due to elevated pressure in the left atrium (LA), plays an essential role in the AF development in pressure-overloaded hearts.
Methods and results
Isolated mouse atrial myocytes subjected to acute axial stretch displayed an immediate elevation of SR Ca2+ leak. Using a mouse model of transverse aortic constriction (TAC), the relation between stretch, SR Ca2+ leak, and AF susceptibility was further tested. At 36 h post-TAC, SR Ca2+ leak in cardiomyocytes from the LA (with haemodynamic stress), but not right atrium (without haemodynamic stress), significantly increased, which was further elevated at 4 weeks post-TAC. Accordingly, AF susceptibility to atrial burst pacing in the 4-week TAC mice were also significantly increased, which was unaffected by inhibition of atrial fibrosis or inflammation via deletion of galectin-3. Western blotting revealed that type 2 ryanodine receptor (RyR2) in left atrial myocytes of TAC mice was oxidized due to activation and up-regulation of Nox2 and Nox4. Direct rescue of dysfunctional RyR2 with dantrolene or rycal S107 reduced diastolic SR Ca2+ leak in left atrial myocytes and prevented atrial burst pacing stimulated AF.
Conclusion
Our study demonstrated for the first time the increased SR Ca2+ leak mediated by enhanced oxidative stress in left atrial myocytes that is causatively associated with higher AF susceptibility in pressure-overloaded hearts.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 20 Mar 2021; 117:1091-1102

Endothelium-restricted endothelin-1 overexpression in type 1 diabetes worsens atherosclerosis and immune cell infiltration via NOX1.

Ouerd S, Idris-Khodja N, Trindade M, Ferreira NS, ... Paradis P, Schiffrin EL
Aims
NADPH oxidase (NOX) 1 but not NOX4-dependent oxidative stress plays a role in diabetic vascular disease, including atherosclerosis. Endothelin (ET)-1 has been implicated in diabetes-induced vascular complications. We showed that crossing mice overexpressing human ET-1 selectively in endothelium (eET-1) with apolipoprotein E knockout (Apoe-/-) mice enhanced high-fat diet-induced atherosclerosis in part by increasing oxidative stress. We tested the hypothesis that ET-1 overexpression in the endothelium would worsen atherosclerosis in type 1 diabetes through a mechanism involving NOX1 but not NOX4.
Methods and results
Six-week-old male Apoe-/- and eET-1/Apoe-/- mice with or without Nox1 (Nox1-/y) or Nox4 knockout (Nox4-/-) were injected intraperitoneally with either vehicle or streptozotocin (55 mg/kg/day) for 5 days to induce type 1 diabetes and were studied 14 weeks later. ET-1 overexpression increased 2.5-fold and five-fold the atherosclerotic lesion area in the aortic sinus and arch of diabetic Apoe-/- mice, respectively. Deletion of Nox1 reduced aortic arch plaque size by 60%; in contrast, Nox4 knockout increased lesion size by 1.5-fold. ET-1 overexpression decreased aortic sinus and arch plaque alpha smooth muscle cell content by ∼35% and ∼50%, respectively, which was blunted by Nox1 but not Nox4 knockout. Reactive oxygen species production was increased two-fold in aortic arch perivascular fat of diabetic eET-1/Apoe-/- and eET-1/Apoe-/-/Nox4-/- mice but not eET-1/Apoe-/-/Nox1y/- mice. ET-1 overexpression enhanced monocyte/macrophage and CD3+ T-cell infiltration ∼2.7-fold in the aortic arch perivascular fat of diabetic Apoe-/- mice. Both Nox1 and Nox4 knockout blunted CD3+ T-cell infiltration whereas only Nox1 knockout prevented the monocyte/macrophage infiltration in diabetic eET-1/Apoe-/- mice.
Conclusion
Endothelium ET-1 overexpression enhances the progression of atherosclerosis in type 1 diabetes, perivascular oxidative stress, and inflammation through NOX1.

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Cardiovasc Res: 20 Mar 2021; 117:1144-1153

Single-cell RNA sequencing reveals cell type- and artery type-specific vascular remodelling in male spontaneously hypertensive rats.

Cheng J, Gu W, Lan T, Deng J, ... Yang Y, Xu Q
Aims
Hypertension is a major risk factor for cardiovascular diseases. However, vascular remodelling, a hallmark of hypertension, has not been systematically characterized yet. We described systematic vascular remodelling, especially the artery type- and cell type-specific changes, in hypertension using spontaneously hypertensive rats (SHRs).
Methods and results
Single-cell RNA sequencing was used to depict the cell atlas of mesenteric artery (MA) and aortic artery (AA) from SHRs. More than 20 000 cells were included in the analysis. The number of immune cells more than doubled in aortic aorta in SHRs compared to Wistar Kyoto controls, whereas an expansion of MA mesenchymal stromal cells (MSCs) was observed in SHRs. Comparison of corresponding artery types and cell types identified in integrated datasets unravels dysregulated genes specific for artery types and cell types. Intersection of dysregulated genes with curated gene sets including cytokines, growth factors, extracellular matrix (ECM), receptors, etc. revealed vascular remodelling events involving cell-cell interaction and ECM re-organization. Particularly, AA remodelling encompasses upregulated cytokine genes in smooth muscle cells, endothelial cells, and especially MSCs, whereas in MA, change of genes involving the contractile machinery and downregulation of ECM-related genes were more prominent. Macrophages and T cells within the aorta demonstrated significant dysregulation of cellular interaction with vascular cells.
Conclusion
Our findings provide the first cell landscape of resistant and conductive arteries in hypertensive animal models. Moreover, it also offers a systematic characterization of the dysregulated gene profiles with unbiased, artery type-specific and cell type-specific manners during hypertensive vascular remodelling.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 20 Mar 2021; 117:1202-1216

Remote ischaemic preconditioning ameliorates anthracycline-induced cardiotoxicity and preserves mitochondrial integrity.

Galán-Arriola C, Villena-Gutiérrez R, Higuero-Verdejo MI, Díaz-Rengifo IA, ... Sánchez-González J, Ibanez B
Aims
Anthracycline-induced cardiotoxicity (AIC) is a serious adverse effect among cancer patients. A central mechanism of AIC is irreversible mitochondrial damage. Despite major efforts, there are currently no effective therapies able to prevent AIC.
Methods and results
Forty Large-White pigs were included. In Study 1, 20 pigs were randomized 1:1 to remote ischaemic preconditioning (RIPC, 3 cycles of 5 min leg ischaemia followed by 5 min reperfusion) or no pretreatment. RIPC was performed immediately before each intracoronary doxorubicin injections (0.45 mg/kg) given at Weeks 0, 2, 4, 6, and 8. A group of 10 pigs with no exposure to doxorubicin served as healthy controls. Pigs underwent serial cardiac magnetic resonance (CMR) exams at baseline and at Weeks 6, 8, 12, and 16, being sacrifice after that. In Study 2, 10 new pigs received 3 doxorubicin injections (with/out preceding RIPC) and were sacrificed at week 6. In Study 1, left ventricular ejection fraction (LVEF) depression was blunted animals receiving RIPC before doxorubicin (RIPC-Doxo), which had a significantly higher LVEF at Week 16 than doxorubicin treated pigs that received no pretreatment (Untreated-Doxo) (41.5 ± 9.1% vs. 32.5 ± 8.7%, P = 0.04). It was mainly due to conserved regional contractile function. In Study 2, transmission electron microscopy (TEM) at Week 6 showed fragmented mitochondria with severe morphological abnormalities in Untreated-Doxo pigs, together with upregulation of fission and autophagy proteins. At the end of the 16-week Study 1 protocol, TEM revealed overt mitochondrial fragmentation with structural fragmentation in Untreated-Doxo pigs, whereas interstitial fibrosis was less severe in RIPC+Doxo pigs.
Conclusion
In a translatable large-animal model of AIC, RIPC applied immediately before each doxorubicin injection resulted in preserved cardiac contractility with significantly higher long-term LVEF and less cardiac fibrosis. RIPC prevented mitochondrial fragmentation and dysregulated autophagy from AIC early stages. RIPC is a promising intervention for testing in clinical trials in AIC.

© The Author(s) 2020. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 20 Mar 2021; 117:1132-1143

Effect of icosapent ethyl on progression of coronary atherosclerosis in patients with elevated triglycerides on statin therapy: a prospective, placebo-controlled randomized trial (EVAPORATE): interim results.

Budoff MJ, Muhlestein JB, Bhatt DL, Le Pa VT, ... Tayek J, Nelson JR
Aims
Though statin therapy is known to slow coronary atherosclerosis progression and reduce cardiovascular (CV) events, significant CV risk still remains. In the REDUCE-IT study, icosapent ethyl (IPE) added to statin therapy reduced initial CV events by 25% and total CV events by 30%, but its effects on coronary atherosclerosis progression have not yet been fully investigated. Therefore, this study is to determine whether IPE 4 g/day will result in a greater change from baseline in plaque volume measured by serial multidetector computed tomography than placebo in statin-treated patients.
Methods and results
EVAPORATE is a randomized, double-blind, placebo-controlled trial. Patients had to have coronary atherosclerosis by coronary computed tomographic angiography (CCTA) (≥1 angiographic stenoses with ≥20% narrowing), on stable statin therapy with low-density lipoprotein cholesterol levels 40-115 mg/dL, and persistently high triglyceride levels (135-499 mg/dL). Patients underwent an interim scan at 9 months and were followed for an additional 9 months with CCTA at 0, 9, and 18 months. Here, we present the protocol-specified interim efficacy results. A total of 80 patients were enrolled, with 67 completing the 9-month visit and having interpretable CCTA at baseline and at 9 months (age = 57 ± 6 years, male = 36, 63%). At the 9-month interim analysis, there was no significant change in low attenuation plaque (LAP) between active and placebo groups (74% vs. 94%, P = 0.469). However, there was slowing of total non-calcified plaque (sum of LAP, fibrofatty, and fibrous plaque) (35% vs. 43%, P = 0.010), total plaque (non-calcified + calcified plaque) (15% vs. 26%, P = 0.0004), fibrous plaque (17% vs. 40%, P = 0.011), and calcified plaque (-1% vs. 9%, P = 0.001), after adjustment by baseline plaque, age, sex, diabetes, baseline triglyceride levels, and statin use.
Conclusion
EVAPORATE is the first study using CCTA to evaluate the effects of IPE as an adjunct to statin therapy on atherosclerotic plaque characteristics in a high-risk CV population with persistently high triglyceride levels. It provides important mechanistic data in regards to the reduction in CV events in the REDUCE-IT clinical trial.
Clinicaltrials. govidentifier
NCT029226027.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 20 Mar 2021; 117:1070-1077

Class switching and high-affinity immunoglobulin G production by B cells is dispensable for the development of hypertension in mice.

Chen Y, Dale BL, Alexander MR, Xiao L, ... Davis GK, Madhur MS
Aims 
Elevated serum immunoglobulins have been associated with experimental and human hypertension for decades but whether immunoglobulins and B cells play a causal role in hypertension pathology is unclear. In this study, we sought to determine the role of B cells and high-affinity class-switched immunoglobulins on hypertension and hypertensive end-organ damage to determine if they might represent viable therapeutic targets for this disease.
Methods and results 
We purified serum immunoglobulin G (IgG) from mice exposed to vehicle or angiotensin (Ang) II to induce hypertension and adoptively transferred these to wild type (WT) recipient mice receiving a subpressor dose of Ang II. We found that transfer of IgG from hypertensive animals does not affect blood pressure, endothelial function, renal inflammation, albuminuria, or T cell-derived cytokine production compared with transfer of IgG from vehicle infused animals. As an alternative approach to investigate the role of high-affinity, class-switched immunoglobulins, we studied mice with genetic deletion of activation-induced deaminase (Aicda-/-). These mice have elevated levels of IgM but virtual absence of class-switched immunoglobulins such as IgG subclasses and IgA. Neither male nor female Aicda-/- mice were protected from Ang II-induced hypertension and renal/vascular damage. To determine if IgM or non-immunoglobulin-dependent innate functions of B cells play a role in hypertension, we studied mice with severe global B-cell deficiency due to deletion of the membrane exon of the IgM heavy chain (µMT-/-). µMT-/- mice were also not protected from hypertension or end-organ damage induced by Ang II infusion or deoxycorticosterone acetate-salt treatment.
Conclusions 
These results suggest that B cells and serum immunoglobulins do not play a causal role in hypertension pathology.

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Cardiovasc Res: 20 Mar 2021; 117:1217-1228

Disruption of actin dynamics regulated by Rho effector mDia1 attenuates pressure overload-induced cardiac hypertrophic responses and exacerbates dysfunction.

Abe I, Terabayashi T, Hanada K, Kondo H, ... Takahashi N, Ishizaki T
Aims
Cardiac hypertrophy is a compensatory response to pressure overload, leading to heart failure. Recent studies have demonstrated that Rho is immediately activated in left ventricles after pressure overload and that Rho signalling plays crucial regulatory roles in actin cytoskeleton rearrangement during cardiac hypertrophic responses. However, the mechanisms by which Rho and its downstream proteins control actin dynamics during hypertrophic responses remain not fully understood. In this study, we identified the pivotal roles of mammalian homologue of Drosophila diaphanous (mDia) 1, a Rho-effector molecule, in pressure overload-induced ventricular hypertrophy.
Methods and results 
Male wild-type (WT) and mDia1-knockout (mDia1KO) mice (10-12 weeks old) were subjected to a transverse aortic constriction (TAC) or sham operation. The heart weight/tibia length ratio, cardiomyocyte cross-sectional area, left ventricular wall thickness, and expression of hypertrophy-specific genes were significantly decreased in mDia1KO mice 3 weeks after TAC, and the mortality rate was higher at 12 weeks. Echocardiography indicated that mDia1 deletion increased the severity of heart failure 8 weeks after TAC. Importantly, we could not observe apparent defects in cardiac hypertrophic responses in mDia3-knockout mice. Microarray analysis revealed that mDia1 was involved in the induction of hypertrophy-related genes, including immediate early genes, in pressure overloaded hearts. Loss of mDia1 attenuated activation of the mechanotransduction pathway in TAC-operated mice hearts. We also found that mDia1 was involved in stretch-induced activation of the mechanotransduction pathway and gene expression of c-fos in neonatal rat ventricular cardiomyocytes (NRVMs). mDia1 regulated the filamentous/globular (F/G)-actin ratio in response to pressure overload in mice. Additionally, increases in nuclear myocardin-related transcription factors and serum response factor were perturbed in response to pressure overload in mDia1KO mice and to mechanical stretch in mDia1 depleted NRVMs.
Conclusion 
mDia1, through actin dynamics, is involved in compensatory cardiac hypertrophy in response to pressure overload.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 20 Mar 2021; 117:1103-1117

Classical monocyte transcriptomes reveal significant anti-inflammatory statin effect in women with chronic HIV.

Ehinger E, Ghosheh Y, Pramod AB, Lin J, ... Kaplan RC, Ley K
Aims
During virally suppressed chronic HIV infection, persistent inflammation contributes to the development of cardiovascular disease (CVD), a major comorbidity in people living with HIV (LWH). Classical blood monocytes (CMs) remain activated during antiretroviral therapy and are a major source of pro-inflammatory and pro-thrombotic factors that contribute to atherosclerotic plaque development and instability.
Methods and results
Here, we identify transcriptomic changes in circulating CMs in peripheral blood mononuclear cell samples from participants of the Women\'s Interagency HIV Study, selected by HIV and subclinical CVD (sCVD) status. We flow-sorted CM from participants of the Women\'s Interagency HIV Study and deep-sequenced their mRNA (n = 92). CMs of HIV+ participants showed elevated interleukin (IL)-6, IL-1β, and IL-12β, overlapping with many transcripts identified in sCVD+ participants. In sCVD+ participants LWH, those reporting statin use showed reduced pro-inflammatory gene expression to a level comparable with healthy (HIV-sCVD-) participants. Statin non-users maintained an elevated inflammatory profile and increased cytokine production.
Conclusion
Statin therapy has been associated with a lower risk of cardiac events, such as myocardial infarction in the general population, but not in those LWH. Our data suggest that women LWH may benefit from statin therapy even in the absence of overt CVD.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 20 Mar 2021; 117:1166-1177

Heart failure with preserved ejection fraction: insights into diagnosis and pathophysiology.

Nagueh SF
Heart failure with preserved ejection fraction (HFpEF) accounts for at least half the cases of heart failure, currently diagnosed. There are several cardiac and non-cardiac manifestations of the syndrome. Structure and function abnormalities can include all four cardiac chambers. The left ventricle has abnormal systolic and diastolic functions which can be examined by invasive and non-invasive measurements. In addition, the left atrium enlarges with abnormal left atrial function, pulmonary hypertension occurs, and the right ventricle can develop hypertrophy, enlargement, and systolic dysfunction. There are a paucity of data on calcium handling in HFpEF patients. Growing literature supports the presence of abnormalities in titin and its phosphorylation, and increased interstitial fibrosis contributing to increased chamber stiffness. A systemic inflammatory state causing reduced myocardial cyclic guanosine monophosphate along with defects in the unfolded protein response have been recently reported. Diagnosis relies on signs and symptoms of heart failure, preserved ejection fraction, and detection of diastolic function abnormalities based on echocardiographic findings and abnormally elevated natriuretic peptide levels or invasive measurements of wedge pressure at rest or with exercise. There are currently two diagnostic algorithms: H2FPEF, and HFA-PEFF with limited data comparing their performance head to head in the same patient population. Despite the growing understanding of the syndrome\'s pathophysiology, there have been little success in developing specific treatment for patients with HFpEF.

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Cardiovasc Res: 20 Mar 2021; 117:999-1014

Mechanism of succinate efflux upon reperfusion of the ischaemic heart.

Prag HA, Gruszczyk AV, Huang MM, Beach TE, ... Murphy MP, Aksentijević D
Aims 
Succinate accumulates several-fold in the ischaemic heart and is then rapidly oxidized upon reperfusion, contributing to reactive oxygen species production by mitochondria. In addition, a significant amount of the accumulated succinate is released from the heart into the circulation at reperfusion, potentially activating the G-protein-coupled succinate receptor (SUCNR1). However, the factors that determine the proportion of succinate oxidation or release, and the mechanism of this release, are not known.
Methods and results 
To address these questions, we assessed the fate of accumulated succinate upon reperfusion of anoxic cardiomyocytes, and of the ischaemic heart both ex vivo and in vivo. The release of accumulated succinate was selective and was enhanced by acidification of the intracellular milieu. Furthermore, pharmacological inhibition, or haploinsufficiency of the monocarboxylate transporter 1 (MCT1) significantly decreased succinate efflux from the reperfused heart.
Conclusion 
Succinate release upon reperfusion of the ischaemic heart is mediated by MCT1 and is facilitated by the acidification of the myocardium during ischaemia. These findings will allow the signalling interaction between succinate released from reperfused ischaemic myocardium and SUCNR1 to be explored.

© The Author(s) 2020. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 20 Mar 2021; 117:1188-1201

Autonomic innervation of the carotid body as a determinant of its sensitivity: implications for cardiovascular physiology and pathology.

Brognara F, Felippe ISA, Salgado HC, Paton JFR
The motivation for this review comes from the emerging complexity of the autonomic innervation of the carotid body (CB) and its putative role in regulating chemoreceptor sensitivity. With the carotid bodies as a potential therapeutic target for numerous cardiorespiratory and metabolic diseases, an understanding of the neural control of its circulation is most relevant. Since nerve fibres track blood vessels and receive autonomic innervation, we initiate our review by describing the origins of arterial feed to the CB and its unique vascular architecture and blood flow. Arterial feed(s) vary amongst species and, unequivocally, the arterial blood supply is relatively high to this organ. The vasculature appears to form separate circuits inside the CB with one having arterial venous anastomoses. Both sympathetic and parasympathetic nerves are present with postganglionic neurons located within the CB or close to it in the form of paraganglia. Their role in arterial vascular resistance control is described as is how CB blood flow relates to carotid sinus afferent activity. We discuss non-vascular targets of autonomic nerves, their possible role in controlling glomus cell activity, and how certain transmitters may relate to function. We propose that the autonomic nerves sub-serving the CB provide a rapid mechanism to tune the gain of peripheral chemoreflex sensitivity based on alterations in blood flow and oxygen delivery, and might provide future therapeutic targets. However, there remain a number of unknowns regarding these mechanisms that require further research that is discussed.

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Cardiovasc Res: 20 Mar 2021; 117:1015-1032

Pathophysiology of atrial fibrillation and chronic kidney disease.

Ding WY, Gupta D, Wong CF, Lip GYH
Atrial fibrillation (AF) and chronic kidney disease (CKD) are closely related conditions with shared risk factors. The growing prevalence of both AF and CKD indicates that more patients will suffer from concurrent conditions. There are various complex interlinking mechanisms with important implications for the management of these patients. Furthermore, there is uncertainty regarding the use of oral anticoagulation (OAC) in AF and CKD that is reflected by a lack of consensus between international guidelines. Therefore, the importance of understanding the implications of co-existing AF and CKD should not be underestimated. In this review, we discuss the pathophysiology and association between AF and CKD, including the underlying mechanisms, risk of thrombo-embolic and bleeding complications, influence on stroke management, and evidence surrounding the use of OAC for stroke prevention.

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Cardiovasc Res: 20 Mar 2021; 117:1046-1059

Impact of protein glycosylation on lipoprotein metabolism and atherosclerosis.

Pirillo A, Svecla M, Catapano AL, Holleboom AG, Norata GD
Protein glycosylation is a post-translational modification consisting in the enzymatic attachment of carbohydrate chains to specific residues of the protein sequence. Several types of glycosylation have been described, with N-glycosylation and O-glycosylation being the most common types impacting on crucial biological processes, such as protein synthesis, trafficking, localization, and function. Genetic defects in genes involved in protein glycosylation may result in altered production and activity of several proteins, with a broad range of clinical manifestations, including dyslipidaemia and atherosclerosis. A large number of apolipoproteins, lipoprotein receptors, and other proteins involved in lipoprotein metabolism are glycosylated, and alterations in their glycosylation profile are associated with changes in their expression and/or function. Rare genetic diseases and population genetics have provided additional information linking protein glycosylation to the regulation of lipoprotein metabolism.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 20 Mar 2021; 117:1033-1045

Isolation and characterization of hESC-derived heart field-specific cardiomyocytes unravels new insights into their transcriptional and electrophysiological profiles.

Pezhouman A, Engel JL, Nguyen NB, Skelton RJP, ... Elliott DA, Ardehali R
Aims
We prospectively isolate and characterize first and second heart field- and nodal-like cardiomyocytes using a double reporter line from human embryonic stem cells. Our double reporter line utilizes two important transcription factors in cardiac development, TBX5 and NKX2-5. TBX5 expression marks first heart field progenitors and cardiomyocytes while NKX2-5 is expressed in nearly all myocytes of the developing heart (excluding nodal cells). We address the shortcomings of prior work in the generation of heart-field specific cardiomyocytes from induced pluripotent stem cells and provide a comprehensive early developmental transcriptomic as well as electrophysiological analyses of these three populations.
Methods and results
Transcriptional, immunocytochemical, and functional studies support the cellular identities of isolated populations based on the expression pattern of NKX2-5 and TBX5. Importantly, bulk and single-cell RNA sequencing analyses provide evidence of unique molecular signatures of isolated first and second heart-field cardiomyocytes, as well as nodal-like cells. Extensive electrophysiological analyses reveal dominant atrial action potential phenotypes in first and second heart fields in alignment with our findings in single-cell RNA sequencing. Lastly, we identify two novel surface markers, POPDC2 and CORIN, that enables purification of cardiomyocytes and first heart field cardiomyocytes, respectively.
Conclusions
We describe a high yield approach for isolation and characterization of human embryonic stem cell-derived heart field specific and nodal-like cardiomyocytes. Obtaining enriched populations of these different cardiomyocyte subtypes increases the resolution of gene expression profiling during early cardiogenesis, arrhythmia modeling, and drug screening. This paves the way for the development of effective stem cell therapy to treat diseases that affect specific regions of the heart or chamber-specific congenital heart defects.
Translational perspective
Myocardial infarction leads to irreversible loss of cardiomyocytes and eventually heart failure. Human embryonic stem cells (hESCs) can be differentiated to cardiomyocytes and are considered a potential source of cell therapy for cardiac regeneration. However, current differentiation strategies yield a mixture of cardiomyocyte subtypes and safety concerns stemming from the use of a heterogenous population of cardiomyocytes have hindered its application. Here, we report generation of enriched heart field-specific cardiomyocytes using a hESC double reporter. Our study facilitates investigating early human cardiogenesis in vitro and generating chamber-specific cardiomyocytes to treat diseases that affect specific regions of the heart.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 20 Mar 2021; epub ahead of print

THE YEAR IN BASIC VASCULAR BIOLOGY RESEARCH: FROM MECHANORECEPTORS AND NETS TO SMARTPHONE DATA AND OMICS.

Evans P, Wojta J, Hoefer IE, Waltenberger J, ... Badimon L, Weber C
2020 has been an extraordinary year. The emergence of COVID-19 has driven urgent research in pulmonary and cardiovascular science and other fields. It has also shaped the way that we work with many experimental laboratories shutting down for several months, while bioinformatics approaches and other large data projects have gained prominence. Despite these setbacks, vascular biology research is stronger than ever. On behalf of the European Society of Cardiology Council for Basic Cardiovascular Science (ESC CBCS), here we review some of the vascular biology research highlights for 2020. This review is not exhaustive and there are many outstanding vascular biology publications that we were unable to cite due to page limits. Notwithstanding this, we have provided a snapshot of vascular biology research excellence in 2020 and identify topics that are in the ascendency and likely to gain prominence in coming years.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 20 Mar 2021; epub ahead of print

Novel approaches to mechanism-based atrial fibrillation ablation.

Quintanilla JG, Shpun S, Jalife J, Filgueiras-Rama D
Modern cardiac electrophysiology has reported significant advances in the understanding of mechanisms underlying complex wave propagation patterns during atrial fibrillation (AF), although disagreements remain. One school of thought adheres to the long-held postulate that AF is the result of randomly propagating wavelets that wonder throughout the atria. Another school supports the notion that AF is deterministic in that it depends on a small number of high-frequency rotors generating three-dimensional scroll waves that propagate throughout the atria. The spiralling waves are thought to interact with anatomic and functional obstacles, leading to fragmentation and new wavelet formation associated with the irregular activation patterns documented on AF tracings. The deterministic hypothesis is consistent with demonstrable hierarchical gradients of activation frequency and AF termination on ablation at specific (non-random) atrial regions. During the last decade, data from realistic animal models and pilot clinical series have triggered a new era of novel methodologies to identify and ablate AF drivers outside the pulmonary veins. New generation electroanatomical mapping systems and multielectrode mapping catheters, complimented by powerful mathematical analyses, have generated the necessary platforms and tools for moving these approaches into clinical procedures. Recent clinical data using such platforms have provided encouraging evidence supporting the feasibility of targeting and effectively ablating driver regions in addition to pulmonary vein isolation in persistent AF. Here, we review state-of-the-art technologies and provide a comprehensive historical perspective, characterization, classification, and expected outcomes of current mechanistically based methods for AF ablation. We discuss also the challenges and expected future directions that scientists and clinicians will face in their efforts to understand AF dynamics and successfully implement any novel method into regular clinical practice.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Public Health Association.

Cardiovasc Res: 20 Mar 2021; epub ahead of print

THE ROLE OF PHOSPHORYLATION IN ATRIAL FIBRILLATION: A FOCUS ON MASS SPECTROMETRY APPROACHES.

Safabakhsh S, Panwar P, Barichello S, Sangha SS, ... Van Petegem F, Laksman Z
Atrial fibrillation (AF) is the most common arrhythmia worldwide. It is associated with significant increases in morbidity in the form of stroke and heart failure, and a doubling in all-cause mortality. The pathophysiology of AF is incompletely understood, and this has contributed to a lack of effective treatments and disease-modifying therapies. An important cellular process that may explain how risk factors give rise to AF includes post-translational modification (PTM) of proteins. As the most commonly occurring PTM, protein phosphorylation is especially relevant. Although many methods exist for studying protein phosphorylation, a common and highly resolute technique is mass spectrometry (MS). This review will discuss recent evidence surrounding the role of protein phosphorylation in the pathogenesis of AF. MS-based technology to study phosphorylation and uses of MS in other areas of medicine such as oncology will also be presented. Based on these data, future goals and experiments will be outlined that utilize MS technology to better understand the role of phosphorylation in AF and elucidate its role in AF pathophysiology. This may ultimately allow for the development of more effective AF therapies.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.

Cardiovasc Res: 20 Mar 2021; epub ahead of print

Clinical Efficacy and Safety of Angiogenesis Inhibitors: Sex Differences and Current Challenges.

Cignarella A, Fadini GP, Bolego C, Trevisi L, ... Rossi GP, Barton M
Vasoactive molecules, such as vascular endothelial growth factor (VEGF) and endothelins, share cytokine-like activities and regulate endothelial cell (EC) growth, migration and inflammation. Some endothelial mediators and their receptors are targets for currently approved angiogenesis inhibitors, drugs that are either monoclonal antibodies raised towards VEGF, or inhibitors of vascular receptor protein kinases and signaling pathways. Pharmacological interference with the protective functions of ECs results in a similar spectrum of adverse effects. Clinically, the most common side effects of VEGF signaling pathway inhibition include an increase in arterial pressure, left ventricular (LV) dysfunction ultimately causing heart failure, and thromboembolic events, including pulmonary embolism, stroke, and myocardial infarction. Sex steroids such as androgens, progestins, and estrogen and their receptors (ERα, ERβ, GPER; PR-A, PR-B; AR) have been identified as important modifiers of angiogenesis, and sex differences have been reported for anti-angiogenic drugs. This review article discusses the current challenges clinicians are facing with regard to angiogenesis inhibitor treatments, including the need to consider sex differences affecting clinical efficacy and safety. We also propose areas for future research taking into account the role of sex hormone receptors and sex chromosomes. Development of new sex-specific drugs with improved target and cell-type selectivity likely will open the way personalized medicine in men and women requiring antiangiogenic therapy and result in reduced adverse effects and improved therapeutic efficacy.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 18 Mar 2021; epub ahead of print

Current progress in clinical, molecular, and genetic aspects of adult fibromuscular dysplasia.

Persu A, Dobrowolski P, Gornik HL, Olin JW, ... Prejbisz A, Januszewicz A
Fibromuscular dysplasia (FMD) is a non-atherosclerotic vascular disease that may involve medium-sized muscular arteries throughout the body. The majority of FMD patients are women. Although a variety of genetic, mechanical, and hormonal factors play a role in the pathogenesis of FMD, overall, its cause remains poorly understood. It is probable that the pathogenesis of FMD is linked to a combination of genetic and environmental factors. Extensive studies have correlated the arterial lesions of FMD to histopathological findings of arterial fibrosis, cellular hyperplasia, and distortion of the abnormal architecture of the arterial wall. More recently, the vascular phenotype of lesions associated with FMD has been expanded to include arterial aneurysms, dissections, and tortuosity. However, in the absence of a string of beads or focal stenosis, these lesions do not suffice to establish the diagnosis. While FMD most commonly involves renal and cerebrovascular arteries, involvement of most arteries throughout the body has been reported. Increasing evidence highlights that FMD is a systemic arterial disease and that subclinical alterations can be found in non-affected arterial segments. Recent significant progress in FMD-related research which has led to improved understandings of the disease\'s clinical manifestations, natural history, epidemiology, and genetics. Ongoing work continues to focus on FMD genetics and proteomics, physiological effects of FMD on cardiovascular structure and function, and novel imaging modalities and blood-based biomarkers that can be used to identify subclinical FMD. It is also hoped that the next decade will bring the development of multi-centred and potentially international clinical trials to provide comparative effectiveness data to inform the optimal management of patients with FMD.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 18 Mar 2021; epub ahead of print

Organ-on-a-chip technology: a novel approach to investigate cardiovascular diseases.

Paloschi V, Sabater-Lleal M, Middelkamp H, Vivas A, ... Tenje M, Maegdefessel L
The development of organs-on-chip has revolutionized in vitro cell culture experiments by allowing a better mimicry of human physiology and pathophysiology that has consequently led researchers to gain more meaningful insights into disease mechanisms. Several models of hearts-on-chips and vessels-on-chips have been demonstrated to recapitulate fundamental aspects of the human cardiovascular system in the recent past. These 2D and 3D systems include synchronized beating cardiomyocytes in hearts-on-chips, and vessels-on-chips with layer-based structures and the inclusion of physiological and pathological shear stress conditions. The opportunities to discover novel targets and to perform drug testing with chip-based platforms have substantially enhanced thanks to the utilization of patient-derived cells and precise control of their microenvironment. These organ models will provide an important asset for future approaches to personalized cardiovascular medicine and improved patient care. However, certain technical and biological challenges remain, making the global utilization of organs-on-chips to tackle unanswered questions in cardiovascular science still rather challenging. This review article aims to introduce and summarize published work on hearts- and vessels-on chips but also to provide an outlook and perspective on how these advanced in vitro systems can be used to tailor disease models with patient-specific characteristics.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 16 Mar 2021; epub ahead of print

Noninvasive peripheral vascular function, incident cardiovascular disease, and mortality in the general population.

Schnabel RB, Magnussen C, Schulz A, Ojeda FM, ... Münzel T, Gutenberg Health Study investigators
Aims
Evidence suggests that peripheral vascular function is related to cardiovascular disease (CVD) and mortality. We evaluated the associations of noninvasive measures of flow-mediated dilatation and peripheral arterial tonometry with incident CVD and mortality.
Methods and results
In a post-hoc analysis of the community-based Gutenberg Health Study, median age 55 years (25th/75th percentile 46/65) and 49.5% women, we measured brachial artery flow-mediated dilatation (N = 12,599) and fingertip peripheral arterial tonometry (N = 11,125). After a follow-up of up to 11.7 years, we observed 595 incident CVD events, 106 cardiac deaths, and 860 deaths in total. Survival curves showed decreased event-free survival with higher mean brachial artery diameter and baseline pulse amplitude and better survival with higher mean flow-mediated dilatation and peripheral arterial tonometry ratio (all Plog rank<0.05). In multivariable-adjusted Cox regression analyses only baseline pulse amplitude was inversely related to mortality ((hazard ratio) per standard deviation increase, 0.86, 95% confidence interval, 0.79-0.94; P = 0.0009). After exclusion of individuals with prevalent cardiovascular disease the association was no longer statistically significant in multivariable-adjusted models (hazard ratio 0.91, 95% confidence interval 0.81-1.02; P = 0.11). None of the vascular variables substantially increased the C-index of a model comprising clinical risk factors.
Conclusions
In our cohort, noninvasive measures of peripheral vascular structure and function did not reveal clinically relevant associations with incident cardiovascular disease or mortality. Whether determination of pulse amplitude by peripheral arterial tonometry improves clinical decision-making in primary prevention needs to be demonstrated.
Translational perspective
In our large middle-aged community cohort with more than 15,000 individuals, median age 55 years (25th/75th percentile 46/65), 49.5% women noninvasively measured peripheral vascular function using flow-mediated dilation after upper arm occlusion or fingertip peripheral arterial tonometry was not relevantly associated with incident cardiovascular disease or mortality in multivariable-adjusted analyses. An interaction of the association of peripheral arterial tonometry with mortality by prevalent cardiovascular disease was observed. Routine measurement of flow-mediated dilation or peripheral arterial tonometry in our community cohort to screen for high risk of cardiovascular disease or mortality was not effective.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 15 Mar 2021; epub ahead of print

Targeting angiotensin type 2 receptors located on pressor neurons in the nucleus of the solitary tract to relieve hypertension in mice.

Mohammed M, Johnson DN, Wang LA, Harden SW, ... Krause EG, de Kloet AD
Aims
These studies evaluate whether angiotensin type-2 receptors (AT2Rs) that are expressed on γ-aminobutyric acid (GABA) neurons in the nucleus of the solitary tract (NTS) represent a novel endogenous blood pressure lowering mechanism.
Methods and results
Experiments combined advanced genetic and neuroanatomical techniques, pharmacology, electrophysiology and optogenetics in mice to define the structure and cardiovascular-related function of NTS neurons that contain AT2R. Using mice with Cre-recombinase directed to the AT2R gene, we discovered that optogenetic stimulation of AT2R-expressing neurons in the NTS increases GABA release and blood pressure. To evaluate the role of the receptor, per se, in cardiovascular regulation, we chronically delivered C21, a selective AT2R agonist, into the brains of normotensive mice and found that central AT2R activation reduces GABA-related gene expression and blunts the pressor responses induced by optogenetic excitation of NTS AT2R neurons. Next, using in situ hybridization, we found that the levels of Agtr2 mRNAs in GABAergic NTS neurons rise during experimentally-induced hypertension, and we hypothesized that this increased expression may be exploited to ameliorate the disease. Consistent with this, final experiments revealed that central administration of C21 attenuates hypertension, an effect that is abolished in mice lacking AT2R in GABAergic NTS neurons.
Conclusions
These studies unveil novel hindbrain circuits that maintain arterial blood pressure, and reveal a specific population of AT2R that can be engaged to alleviate hypertension. The implication is that these discrete receptors may serve as an access point for activating an endogenous depressor circuit.
Translational perspective
Hypertension is a widespread health problem and risk factor for cardiovascular disease and stroke. Although treatment options exist, many patients suffer from resistant hypertension, which is associated with enhanced sympathetic drive. Thus, many available therapeutics focus on dampening pressor mechanisms. The present studies take the alternative approach of treating hypertension by exploiting an endogenous depressor mechanism.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 15 Mar 2021; epub ahead of print

New aspects of endocrine control of atrial fibrillation and possibilities for clinical translation.

Aguilar M, Rose RA, Takawale A, Nattel S, Reilly S
Hormones are potent endo-, para- and autocrine endogenous regulators of the function of multiple organs, including the heart. Endocrine dysfunction promotes a number of cardiovascular diseases, including atrial fibrillation (AF). While the heart is a target for endocrine regulation, it is also an active endocrine organ itself, secreting a number of important bioactive hormones that convey significant endocrine effects, but also through para-/autocrine actions, actively participate in cardiac self-regulation. The hormones regulating heart-function work in concert to support myocardial performance. AF is a serious clinical problem associated with increased morbidity and mortality, mainly due to stroke and heart failure. Current therapies for AF remain inadequate. AF is characterized by altered atrial function and structure, including electrical and profibrotic remodeling in the atria and ventricles, which facilitates AF progression and hampers its treatment. Although features of this remodeling are well-established and its mechanisms are partly understood, important pathways pertinent to AF arrhythmogenesis are still unidentified. The discovery of these missing pathways has the potential to lead to therapeutic breakthroughs. Endocrine dysfunction is well-recognized to lead to AF. In this review, we discuss endocrine and cardiocrine signaling systems that directly, or as a consequence of an underlying cardiac pathology, contribute to AF pathogenesis. More specifically, we consider the roles of products from the hypothalamic-pituitary axis, the adrenal glands, adipose tissue, the renin-angiotensin system, atrial cardiomyocytes and the thyroid gland in controlling atrial electrical and structural properties. The influence of endocrine/paracrine dysfunction on AF risk and mechanisms is evaluated and discussed. We focus on the most recent findings and reflect on the potential of translating them into clinical application.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 15 Mar 2021; epub ahead of print

Remodelling of adult cardiac tissue subjected to physiological and pathological mechanical load in vitro.

Pitoulis FG, Nunez-Toldra R, Xiao K, Kit-Anan W, ... de Tombe PP, Terracciano CM
Aims
Cardiac remodelling is the process by which the heart adapts to its environment. Mechanical load is a major driver of remodelling. Cardiac tissue culture has been frequently employed for in vitro studies of load-induced remodelling; however, current in vitro protocols (e.g. cyclic stretch, isometric load, auxotonic load) are oversimplified and do not accurately capture the dynamic sequence of mechanical conformational changes experienced by the heart in vivo. This limits translational scope and relevance of findings.
Methods and results
We developed a novel methodology to study chronic load in vitro. We first developed a bioreactor that can recreate the electromechanical events of in vivo pressure-volume loops as in vitro force-length loops. We then used the bioreactor to culture rat living myocardial slices (LMS) for 3 days. The bioreactor operated on the basis of a 3-Element Windkessel circulatory model enabling tissue mechanical loading based on physiologically relevant parameters of afterload and preload. LMS were continuously stretched/relaxed during culture simulating conditions of physiological load (normal preload & afterload), pressure-overload (normal preload & high afterload), or volume-overload (high preload & normal afterload). At the end of culture, functional, structural, and molecular assays were performed to determine load-induced remodelling.Both pressure- and volume-overloaded LMS showed significantly decreased contractility that was more pronounced in the latter compared with physiological load p < 0.0001). Overloaded groups also showed cardiomyocyte hypertrophy; RNAseq identified shared and unique genes expressed in each overload group. The PI3K-Akt pathway was dysregulated in volume-overload while inflammatory pathways were mostly associated with remodelling in pressure-overloaded LMS.
Conclusion
We have developed a proof-of-concept platform and methodology to recreate remodelling under pathophysiological load in vitro. We show that LMS cultured in our bioreactor remodel as a function of the type of mechanical load applied to them.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 15 Mar 2021; epub ahead of print

Metabolic alterations in a rat model of Takotsubo syndrome.

Godsman N, Kohlhaas M, Nickel A, Cheyne L, ... Maack C, Dawson DK
Aims
Cardiac energetic impairment is a major finding in takotsubo patients. We investigate specific metabolic adaptations to direct future therapies.
Methods and results
An isoprenaline-injection female rat model (versus sham) was studied at day-3; recovery assessed at day-7. Substrate uptake, metabolism, inflammation and remodelling were investigated by 18F-FDG-PET, metabolomics, qPCR and WB. Isolated cardiomyocytes were patch-clamped during stress protocols for redox states of NAD(P)H/FAD or [Ca2+]c, [Ca2+]m and sarcomere length. Mitochondrial respiration was assessed by seahorse/Clark electrode (glycolytic and β-oxidation substrates).Cardiac 18F-FDG metabolic rate was increased in takotsubo (p = 0.006), as were expression of GLUT4-RNA/GLUT1/HK2-RNA and HK activity (all p < 0.05), with concomitant accumulation of glucose- and fructose-6-phosphates (p > 0.0001). Both lactate and pyruvate were lower (p < 0.05) despite increases in LDH-RNA and PDH (p < 0.05 both). β-oxidation enzymes CPT1b-RNA and 3KAT were increased (p < 0.01) but malonyl-CoA (CPT-1 regulator) was upregulated (p = 0.01) with decreased fatty acids and acyl-carnitines levels (p = 0.0001-0.02). Krebs cycle intermediates α-ketoglutarate and succinyl-carnitine were reduced (p < 0.05) as was cellular ATP reporter dihydroorotate (p = 0.003). Mitochondrial Ca2+ uptake during high workload was impaired on day-3 (p < 0.0001), inducing oxidation of NAD(P)H and FAD (p = 0.03) but resolved by day-7. There were no differences in mitochondrial respiratory function, sarcomere shortening or [Ca2+] transients of isolated cardiomyocytes, implying preserved integrity of both mitochondria and cardiomyocyte. Inflammation and remodelling were upregulated - increased CD68-RNA, collagen RNA/protein and skeletal actin RNA (all p < 0.05).
Conclusion
Dys-regulation of glucose and lipid metabolic pathways with decreases in final glycolytic and β-oxidation metabolites and reduced availability of Krebs intermediates characterises takotsubo myocardium. The energetic deficit accompanies defective Ca2+ handling, inflammation and upregulation of remodelling pathways, with preservation of sarcomeric and mitochondrial integrity.
Translational perspective
The simultaneous dysregulation in the glycolytic and beta-oxidation pathways which underlies the energetic deficit of the takotsubo heart supports further testing of currently available metabolic modulators as possible candidates for successful therapy, as well as targeting the inflammatory and remodelling pathways.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 11 Mar 2021; epub ahead of print

Human cardiosphere-derived stromal cells exposed to SARS-CoV-2 evolve into hyper-inflammatory/pro-fibrotic phenotype and produce infective viral particles depending on the levels of ACE2 receptor expression.

Amendola A, Garoffolo G, Songia P, Nardacci R, ... Poggio P, Pesce M
Aims
Patients with severe respiratory syndrome caused by SARS-CoV-2 undergo cardiac complications due to hyper-inflammatory conditions. Although the presence of the virus has been detected in the myocardium of infected patients, and infection of induced pluripotent cells-derived cardiomyocytes has been demonstrated, the reported expression of ACE2 in cardiac stromal cells suggests that SARS-CoV-2 may determine cardiac injury by sustaining productive infection and increasing inflammation.
Methods and results
We analyzed expression of ACE2 receptor in primary human cardiac stromal cells derived from cardiospheres, using proteomics and transcriptomics before exposing them to SARS-CoV-2 in vitro. Using conventional and high sensitivity PCR methods, we measured virus release in the cellular supernatants and monitored the intracellular viral bioprocessing. We performed high-resolution imaging to show the sites of intracellular viral production and demonstrated the presence of viral particles in the cells with electron microscopy. We finally used RT-qPCR assays to detect genes linked to innate immunity and fibrotic pathways coherently regulated in cells after exposure to the virus.
Conclusions
Our findings indicate that cardiac stromal cells are susceptible to SARS-CoV-2 infection and produce variable viral yields depending on the extent of cellular ACE2 receptor expression. Interestingly, these cells also evolved toward hyper-inflammatory/pro-fibrotic phenotypes independently of ACE2 levels. Thus, SARS-CoV-2 infection of myocardial stromal cells could be involved in cardiac injury, and explain the high number of complications observed in severe cases of COVID-19.
Translational perspective
In the present investigation, we provide evidence that human cardiac stromal cells, a major component of the non-contractile cellular fraction in the heart can be infected by SARS-CoV-2 in vitro, in direct relationship to the extent of ACE2 receptor expression. Our work also suggests that these cells, when exposed to the virus, can evolve toward inflammatory and fibrotic phenotypes independently of ACE2. In addition to describing a novel cellular target of SARS-CoV-2 in the human heart, our study generates new hypothesis on potential mechanisms underlying cardiac complications observed in COVID-19 patients.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 09 Mar 2021; epub ahead of print

Ketone Therapy for Heart Failure: Current Evidence for Clinical Use.

Takahara S, Soni S, Maayah ZH, Ferdaoussi M, Dyck JRB
During conditions that result in depleted circulating glucose levels, ketone bodies synthesized in the liver are necessary fuel substrates for the brain. In other organs such as the heart, the reliance on ketones for generating energy is less life threatening as the heart can utilize alternative fuel sources such as fatty acids. However, during pathophysiological conditions such as heart failure, cardiac defects in metabolic processes that normally allow for sufficient energy production from fatty acids and carbohydrates contribute to a decline in contractile function. As such, it has been proposed that the failing heart relies more on ketone bodies as an energy source than previously appreciated. Furthermore, it has been suggested that ketone bodies may function as signaling molecules that can suppress systemic and cardiac inflammation. Thus, it is possible that intentionally elevating circulating ketones may be beneficial as an adjunct treatment for heart failure. Although many approaches can be used for \'ketone therapy\', each of these has their own advantages and disadvantages in the treatment of heart failure. Thus, we summarize current preclinical and clinical studies involving various types of ketone therapy in cardiac disease and discuss the advantages and disadvantages of each modality as possible treatments for heart failure.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 09 Mar 2021; epub ahead of print

Rosuvastatin for the prevention of venous thromboembolism: a pooled analysis of the HOPE-3 and JUPITER randomized controlled trials.

Joseph P, Glynn R, Lonn E, Ramasundarahettige C, ... Ridker P, Yusuf S
Aims
To examine the association between rosuvastatin and VTE risk, and whether effects vary in different subpopulations stratified by key demographic, cardiovascular disease (CVD) risk factors and other risk factors associated with VTE.
Methods and results
An individual participant data meta-analysis was conducted across two randomized controlled trials in 30,507 participants over a mean follow up of 3.62 years, Individuals had no prior history of vascular disease but were at intermediate CV risk. In both trials, participants were randomized to receive rosuvastatin or matching placebo. The primary outcome was VTE during follow-up, defined as either deep vein thrombosis or pulmonary embolism. Associations between rosuvastatin and VTE were examined in the overall pooled cohort, and subpopulations stratified by demographic risk factors (i.e. age, sex), CVD risk factors (i.e. obesity, smoking, lipid levels, blood pressure levels, C-reactive protein level), and a history of cancer.Mean age was 65.96 (SD 7.19) years of age, and 17,832 (58.45%) were male. 5,434 (17.82%) were smokers, median BMI was 27.6 (Interquartile range [IQR] 24.7 - 31.1) kg/m2, and median CRP level was 3.4 (IQR 2.1 - 6.0) mg/L. There were 139 VTE events. In the pooled cohort, rosuvastatin was associated with a large proportional reduction in the risk of VTE (hazard ratio 0.53, 95% CI 0.37 - 0.75). No significant interactions were observed between treatment with rosuvastatin and the risk of VTE across subpopulations stratified by demographic, CVD risk factors or a history of cancer (p-values for interactions >0.05 for all subgroups).
Conclusions
Rosuvastatin is associated with a 47% proportional reduction in the risk of VTE, and its effect is consistent both in the presence or absence of VTE related clinical risk factors.
Translational perspective
In this individual participant data meta-analysis of two large randomized controlled trials comparing rosuvastatin to placebo, rosuvastatin was associated with a 47% proportional reduction in the risk of VTE. The effect of rosuvastatin was consistent across a broad range of demographic factors, cardiovascular risk factors, and a history of cancer. This study demonstrates that rosuvastatin is broadly affective at reducing the risk of VTE both in the presence or absence of VTE associated clinical risk factors. Results inform future research on the use of statins for this indication.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 09 Mar 2021; epub ahead of print

Inhibiting cardiac myeloperoxidase alleviates the relaxation defect in hypertrophic cardiomyocytes.

Ramachandra CJA, Kp MMJ, Chua J, Hernandez-Resendiz S, ... Shim W, Hausenloy DJ
Aims
Hypertrophic cardiomyopathy (HCM) is characterised by cardiomyocyte hypertrophy and disarray, and myocardial stiffness due to interstitial fibrosis, which result in impaired left ventricular filling and diastolic dysfunction. The latter manifests as exercise intolerance, angina, and dyspnoea. There is currently no specific treatment for improving diastolic function in HCM. Here, we investigated whether myeloperoxidase (MPO) is expressed in cardiomyocytes and provides a novel therapeutic target for alleviating diastolic dysfunction in HCM.
Methods and results
Human cardiomyocytes derived from control induced pluripotent stem cells (iPSC-CMs) were shown to express MPO, with MPO levels being increased in iPSC-CMs generated from two HCM patients harbouring sarcomeric mutations in the MYBPC3 and MYH7 genes. The presence of cardiomyocyte MPO was associated with higher chlorination and peroxidation activity, increased levels of 3-chlorotyrosine-modified cardiac myosin binding protein-C (MYBPC3), attenuated phosphorylation of MYBPC3 at Ser-282, perturbed calcium signalling, and impaired cardiomyocyte relaxation. Interestingly, treatment with the MPO inhibitor, AZD5904, reduced 3-chlorotyrosine-modified MYBPC3 levels, restored MYBPC3 phosphorylation, and alleviated the calcium signalling and relaxation defects. Finally, we found that MPO protein was expressed in healthy adult murine and human cardiomyocytes, and MPO levels were increased in diseased hearts with left ventricular hypertrophy.
Conclusion
This study demonstrates that MPO inhibition alleviates the relaxation defect in hypertrophic iPSC-CMs through MYBPC3 phosphorylation. These findings highlight cardiomyocyte MPO as a novel therapeutic target for improving myocardial relaxation associated with HCM, a treatment strategy which can be readily investigated in the clinical setting, given that MPO inhibitors are already available for clinical testing.
Translational perspective
There are currently no specific therapies for improving diastolic function in patients with HCM. We show for the first time that myeloperoxidase (MPO) is present in and is up-regulated in cardiomyocytes derived from human iPSCs obtained from HCM patients, where it impairs cardiomyocyte relaxation by reducing phosphorylation of cardiac MYBPC3. Treatment with the MPO inhibitor, AZD5904, restored MYBPC3 phosphorylation and alleviated the relaxation defect, demonstrating cardiomyocyte MPO to be a novel therapeutic target for improving diastolic function in HCM, a treatment strategy which can be evaluated in HCM patients given that MPO inhibitors are already available for clinical testing.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 09 Mar 2021; epub ahead of print

Pharmacological treatment with FGF21 strongly improves plasma cholesterol metabolism to reduce atherosclerosis.

Liu C, Schönke M, Zhou E, Li Z, ... Wang Y, Rensen PCN
Aims
Fibroblast growth factor (FGF) 21, a key regulator of energy metabolism, is currently evaluated in humans for treatment of type 2 diabetes and nonalcoholic steatohepatitis. However, the effects of FGF21 on cardiovascular benefit, particularly on lipoprotein metabolism in relation to atherogenesis, remain elusive.
Methods and results
Here, the role of FGF21 in lipoprotein metabolism in relation to atherosclerosis development was investigated by pharmacological administration of a half-life extended recombinant FGF21 protein to hypercholesterolemic APOE*3-Leiden.CETP mice, a well-established model mimicking atherosclerosis initiation and development in humans. FGF21 reduced plasma total cholesterol, explained by a reduction in non-HDL-cholesterol. Mechanistically, FGF21 promoted brown adipose tissue (BAT) activation and white adipose tissue (WAT) browning, thereby enhancing the selective uptake of fatty acids from triglyceride-rich lipoproteins into BAT and into browned WAT, consequently accelerating the clearance of the cholesterol-enriched remnants by the liver. In addition, FGF21 reduced body fat, ameliorated glucose tolerance and markedly reduced hepatic steatosis, related to upregulated hepatic expression of genes involved in fatty acid oxidation and increased hepatic VLDL-triglyceride secretion. Ultimately, FGF21 largely decreased atherosclerotic lesion area, which was mainly explained by the reduction in non-HDL-cholesterol as shown by linear regression analysis, decreased lesion severity and increased atherosclerotic plaque stability index.
Conclusions
FGF21 improves hypercholesterolemia by accelerating triglyceride-rich lipoprotein turnover as a result of activating BAT and browning of WAT, thereby reducing atherosclerotic lesion severity and increasing atherosclerotic lesion stability index. We have thus provided additional support for the clinical use of FGF21 in the treatment of atherosclerotic cardiovascular disease.
Translational perspectives
Current therapeutics do not fully block atherosclerosis development, indicating a need for additional effective therapeutics. Here, we demonstrate that pharmacological treatment with recombinant FGF21 potently protects against atherosclerosis in APOE*3-Leiden.CETP mice. Mechanistically, FGF21 reduces hypercholesterolemia by accelerating triglyceride-rich lipoprotein turnover as a result of enhancing adipose tissue thermogenesis, thereby alleviating atherosclerotic lesion formation and severity. Consistent with our animal findings, FGF21 administration in obese patients has shown to reduce several cardiovascular risk factors such as obesity and dyslipidemia. Therefore, our present results, together with available clinical data, suggest that FGF21 is a promising therapeutic for atherosclerotic diseases.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 07 Mar 2021; epub ahead of print

Alternative strategies in cardiac preclinical research and new clinical trial formats.

Kreutzer FP, Meinecke A, Schmidt K, Fiedler J, Thum T
An efficient and safe drug development process is crucial for the establishment of new drugs on the market aiming to increase quality of life and life-span of our patients. Despite technological advances in the past decade, successful launches of drug candidates per year remain low. We here give an overview about some of these advances and suggest improvements for implementation to boost preclinical and clinical drug development with a focus on the cardiovascular field. We highlight advantages and disadvantages of animal experimentation and thoroughly review alternatives in the field of three-dimensional cell culture as well as preclinical use of spheroids and organoids. Microfluidic devices and their potential as organ-on-a-chip systems, as well as the use of living animal and human cardiac tissues are additionally introduced. In the second part, we examine recent gold standard randomized clinical trials and present possible modifications to increase lead candidate throughput: adaptive designs, master protocols and drug repurposing. In silico and N-of-1 trials have the potential to redefine clinical drug candidate evaluation. Finally, we briefly discuss clinical trial designs during pandemic times.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 07 Mar 2021; epub ahead of print

New biomarkers from multiomics approaches - improving risk prediction of atrial fibrillation.

Kornej J, Hanger VA, Trinquart L, Ko D, ... Benjamin EJ, Lin H
Atrial fibrillation (AF) is a common cardiac arrhythmia leading to many adverse outcomes and increased mortality. Yet the molecular mechanisms underlying AF remain largely unknown. Recent advances in high-throughput technologies make large-scale molecular profiling possible. In the past decade, multiomics studies of AF have identified a number of potential biomarkers of AF. In this review, we focus on the studies of multiomics profiles with AF risk. We summarize recent advances in the discovery of novel biomarkers for AF through multiomics studies. We also discuss limitations and future directions in risk assessment and discovery of therapeutic targets for AF.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 04 Mar 2021; epub ahead of print

Targeted delivery of Protein Arginine Deiminase-4 inhibitors to limit arterial intimal NETosis and preserve endothelial integrity.

Molinaro R, Yu M, Sausen G, Bichsel CA, ... Shi J, Libby P
Aims
Recent evidence suggests that \"vulnerable plaques,\" which have received intense attention as underlying mechanism of acute coronary syndromes over the decades, actually rarely rupture and cause clinical events. Superficial plaque erosion has emerged as a growing cause of residual thrombotic complications of atherosclerosis in an era of increased preventive measures including lipid lowering, anti-hypertensive therapy, and smoking cessation. The mechanisms of plaque erosion remain poorly understood, and we currently lack validated effective diagnostics or therapeutics for superficial erosion. Eroded plaques have a rich extracellular matrix, an intact fibrous cap, sparse lipid, and few mononuclear cells, but do harbor neutrophil extracellular traps (NETs). We recently reported that NETs amplify and propagate the endothelial damage at the site of arterial lesions that recapitulate superficial erosion in mice. We showed that genetic loss of protein arginine deiminase (PAD)-4 function inhibited NETosis and preserved endothelial integrity. The current study used systemic administration of targeted nanoparticles to deliver an agent that limits NETs formation to probe mechanisms of and demonstrate a novel therapeutic approach to plaque erosion that limits endothelial damage.
Methods and results
We developed Collagen IV-targeted nanoparticles (Col IV NP) to deliver PAD4 inhibitors selectively to regions of endothelial cell sloughing and collagen IV-rich basement membrane exposure. We assessed the binding capability of the targeting ligand in vitro and evaluated Col IV NP targeting to areas of denuded endothelium in vivo in a mouse preparation that recapitulates features of superficial erosion. Delivery of the PAD4 inhibitor GSK484 reduced NET accumulation at sites of intimal injury and preserved endothelial continuity.
Conclusions
NPs directed to Col IV show selective uptake and delivery of their payload to experimentally eroded regions, illustrating their translational potential. Our results further support the role of PAD4 and NETs in superficial erosion.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions please email: [email protected]

Cardiovasc Res: 04 Mar 2021; epub ahead of print

Cardiovascular Informatics: building a bridge to data harmony.

Caufield JH, Sigdel D, Fu J, Choi H, ... Wang D, Ping P
The search for new strategies for better understanding cardiovascular disease is a constant one, spanning multitudinous types of observations and studies. A comprehensive characterization of each disease state and its biomolecular underpinnings relies upon insights gleaned from extensive information collection of various types of data. Researchers and clinicians in cardiovascular biomedicine repeatedly face questions regarding which types of data may best answer their questions, how to integrate information from multiple datasets of various types, and how to adapt emerging advances in machine learning and/or artificial intelligence to their needs in data processing. Frequently lauded as a field with great practical and translational potential, the interface between biomedical informatics and cardiovascular medicine is challenged with staggeringly massive datasets. Successful application of computational approaches to decode these complex and gigantic amounts of information becomes an essential step toward realizing the desired benefits. In this review, we examine recent efforts to adapt informatics strategies to cardiovascular biomedical research: automated information extraction and unification of multifaceted -omics data. We discuss how and why this interdisciplinary space of Cardiovascular Informatics is particularly relevant to and supportive of current experimental and clinical research. We describe in detail how open data sources and methods can drive discovery while demanding few initial resources, an advantage afforded by widespread availability of cloud computing-driven platforms. Subsequently, we provide examples of how interoperable computational systems facilitate exploration of data from multiple sources, including both consistently-formatted structured data and unstructured data. Taken together, these approaches for achieving data harmony enable molecular phenotyping of cardiovascular (CV) diseases and unification of cardiovascular knowledge.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 04 Mar 2021; epub ahead of print

Sex differences in acute cardiovascular care: a review and needs assessment.

Vallabhajosyula S, Verghese D, Desai VK, Sundaragiri PR, Miller VM
Despite significant progress in the care of patients suffering from cardiovascular disease, there remains a persistent sex disparity in the diagnosis, management, and outcomes of these patients. These sex disparities are seen across the spectrum of cardiovascular care, but, are especially pronounced in acute cardiovascular care. The spectrum of acute cardiovascular care encompasses critically ill or tenuous patients with cardiovascular conditions that require urgent or emergent decision-making and interventions. In this narrative review, the disparities in the clinical course, management, and outcomes of six commonly encountered acute cardiovascular conditions, some with a known sex-predilection will be discussed within the basis of underlying sex differences in physiology, anatomy, and pharmacology with the goal of identifying areas where improvement in clinical approaches are needed.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 04 Mar 2021; epub ahead of print

Prevalence of microvascular angina among patients with stable symptoms in the absence of obstructive coronary artery disease: a systematic review.

Aribas E, van Lennep JER, Elias-Smale SE, Piek JJ, ... Appelman Y, Kavousi M
Aims
Our purpose was to perform a systematic review to assess the prevalence of microvascular angina (MVA) among patients with stable symptoms in the absence of obstructive coronary artery disease (CAD). We performed a systematic review of the literature to group the prevalence of MVA, based on diagnostic pathways and modalities.
Methods and results
We defined MVA using three definitions: 1. suspected MVA using non-invasive ischemia tests; proportion of patients with non-obstructive CAD among patients with symptoms and a positive non-invasive ischemia test result, 2. suspected MVA using specific modalities for MVA; proportion of patients with evidence of impaired microvascular function among patients with symptoms and non-obstructive CAD, 3. definitive MVA; proportion of patients with positive ischemia test results among patients with an objectified impaired microvascular dysfunction. We further examined the ratio of women-to-men for the different groups.Of the 4547 abstracts, 20 studies reported data on MVA prevalence. The median prevalence was 43% for suspected MVA using non-invasive ischemia test, 28% for suspected MVA using specific modalities for MVA and 30% for definitive MVA. Overall, more women were included in the studies reporting sex-specific data. The women-to-men ratio for included participants was 1.29. However, the average women-to-men ratio for the MVA cases was 2.50.
Conclusions
In patients with stable symptoms of ischemia in the absence of CAD, the prevalences of suspected and definitive MVA are substantial. The results of this study should warrant cardiologists to support, promote and facilitate the comprehensive evaluation of the coronary microcirculation for all patients with symptoms and non-obstructive CAD.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 01 Mar 2021; epub ahead of print

Paclitaxel mitigates structural alterations and cardiac conduction system defects in a mouse model of Hutchinson-Gilford progeria syndrome.

Macías Á, Díaz-Larrosa JJ, Blanco Y, Fanjul V, ... Jalife J, Andrés V
Aims
Hutchinson-Gilford progeria syndrome (HGPS) is an ultrarare laminopathy caused by expression of progerin, a lamin A variant, also present at low levels in non-HGPS individuals. HGPS patients age and die prematurely, predominantly from cardiovascular complications. Progerin-induced cardiac repolarization defects have been described previously, although the underlying mechanisms are unknown.
Methods and results
We conducted studies in heart tissue from progerin-expressing LmnaG609G/G609G (G609G) mice, including microscopy, intracellular calcium dynamics, patch-clamping, in vivo magnetic resonance imaging, and electrocardiography. Mouse G609G cardiomyocytes showed tubulin-cytoskeleton disorganization, t-tubular system disruption, sarcomere shortening, altered excitation-contraction coupling, and reductions in ventricular thickening and cardiac index. G609G mice exhibited severe bradycardia, and significant alterations of atrio-ventricular conduction and repolarization. Most importantly, 50% of G609G mice had altered heart rate variability, and sinoatrial block, both significant signs of premature cardiac aging. G609G cardiomyocytes had electrophysiological alterations which result in an elevated action potential plateau and early afterdepolarization bursting, reflecting slower sodium current inactivation and long Ca+2 transient duration, which may also help explain the mild QT prolongation in some HGPS patients. Chronic treatment with low-dose paclitaxel ameliorated structural and functional alterations in G609G hearts.
Conclusions
Our results demonstrate that tubulin-cytoskeleton disorganization in progerin-expressing cardiomyocytes causes structural, cardiac conduction and excitation-contraction coupling defects, all of which can be partially corrected by chronic treatment with low-dose of paclitaxel.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 23 Feb 2021; epub ahead of print

The vasculature: a therapeutic target in heart failure?

Luxán G, Dimmeler S
It is well established that the vasculature plays a crucial role in maintaining oxygen and nutrients supply to the heart. Increasing evidence further suggest that the microcirculation has additional roles in supporting a healthy microenvironment. Heart failure is well known to be associated with changes and functional impairment of the microvasculature. The specific ablation of protective signals in endothelial cells in experimental models is sufficient to induce heart failure. Therefore, restoring a healthy endothelium and microcirculation may be a valuable therapeutic strategy to treat heart failure. The present review article will summarize the current understanding of the vascular contribution to heart failure with reduced or preserved ejection fraction. Novel therapeutic approaches including next generation pro-angiogenic therapies and non-coding RNA therapeutics, as well as the targeting of metabolites or metabolic signaling, vascular inflammation and senescence will be discussed.

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 22 Feb 2021; epub ahead of print

Sustained subcutaneous delivery of secretome of human cardiac stem cells promotes cardiac repair following myocardial infarction.

Kompa AR, Greening DW, Kong AM, McMillan PJ, ... Hausenloy DJ, Lim SY
Aims
To establish pre-clinical proof of concept that sustained subcutaneous delivery of the secretome of human cardiac stem cells (CSCs) can be achieved in vivo to produce significant cardioreparative outcomes in the setting of myocardial infarction.
Methods and results
Rats were subjected to permanent ligation of left anterior descending coronary artery and randomized to receive subcutaneous implantation of TheraCyte devices containing either culture media as control or 1 × 106 human W8B2+ CSCs, immediately following myocardial ischaemia. At 4 weeks following myocardial infarction, rats treated with W8B2+ CSCs encapsulated within the TheraCyte device showed preserved left ventricular ejection fraction. The preservation of cardiac function was accompanied by reduced fibrotic scar tissue, interstitial fibrosis, cardiomyocyte hypertrophy, as well as increased myocardial vascular density. Histological analysis of the TheraCyte devices harvested at 4 weeks post-implantation demonstrated survival of human W8B2+ CSCs within the devices, and the outer membrane was highly vascularized by host blood vessels. Using CSCs expressing plasma membrane reporters, extracellular vesicles of W8B2+ CSCs were found to be transferred to the heart and other organs at 4 weeks post-implantation. Furthermore, mass spectrometry-based proteomic profiling of extracellular vesicles of W8B2+ CSCs identified proteins implicated in inflammation, immunoregulation, cell survival, angiogenesis, as well as tissue remodelling and fibrosis that could mediate the cardioreparative effects of secretome of human W8B2+ CSCs.
Conclusions
Subcutaneous implantation of TheraCyte devices encapsulating human W8B2+ CSCs attenuated adverse cardiac remodelling and preserved cardiac function following myocardial infarction. The TheraCyte device can be employed to deliver stem cells in a minimally invasive manner for effective secretome-based cardiac therapy.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Feb 2021; 117:918-929

Identification of an amino-terminus determinant critical for ryanodine receptor/Ca2+ release channel function.

Seidel M, de Meritens CR, Johnson L, Parthimos D, ... Lai FA, Zissimopoulos S
Aims 
The cardiac ryanodine receptor (RyR2), which mediates intracellular Ca2+ release to trigger cardiomyocyte contraction, participates in development of acquired and inherited arrhythmogenic cardiac disease. This study was undertaken to characterize the network of inter- and intra-subunit interactions regulating the activity of the RyR2 homotetramer.
Methods and results 
We use mutational investigations combined with biochemical assays to identify the peptide sequence bridging the β8 with β9 strand as the primary determinant mediating RyR2 N-terminus self-association. The negatively charged side chains of two aspartate residues (D179 and D180) within the β8-β9 loop are crucial for the N-terminal inter-subunit interaction. We also show that the RyR2 N-terminus domain interacts with the C-terminal channel pore region in a Ca2+-independent manner. The β8-β9 loop is required for efficient RyR2 subunit oligomerization but it is dispensable for N-terminus interaction with C-terminus. Deletion of the β8-β9 sequence produces unstable tetrameric channels with subdued intracellular Ca2+ mobilization implicating a role for this domain in channel opening. The arrhythmia-linked R176Q mutation within the β8-β9 loop decreases N-terminus tetramerization but does not affect RyR2 subunit tetramerization or the N-terminus interaction with C-terminus. RyR2R176Q is a characteristic hypersensitive channel displaying enhanced intracellular Ca2+ mobilization suggesting an additional role for the β8-β9 domain in channel closing.
Conclusion 
These results suggest that efficient N-terminus inter-subunit communication mediated by the β8-β9 loop may constitute a primary regulatory mechanism for both RyR2 channel activation and suppression.

© The Author(s) 2020. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 21 Feb 2021; 117:780-791

Sectm1a deficiency aggravates inflammation-triggered cardiac dysfunction through disruption of LXRα signalling in macrophages.

Li Y, Deng S, Wang X, Huang W, ... Peng J, Fan GC
Aims
Cardiac dysfunction is a prevalent comorbidity of disrupted inflammatory homeostasis observed in conditions such as sepsis (acute) or obesity (chronic). Secreted and transmembrane protein 1a (Sectm1a) has previously been implicated to regulate inflammatory responses, yet its role in inflammation-associated cardiac dysfunction is virtually unknown.
Methods and results
Using the CRISPR/Cas9 system, we generated a global Sectm1a-knockout (KO) mouse model and observed significantly increased mortality and cardiac injury after lipopolysaccharide (LPS) injection, when compared with wild-type (WT) control. Further analysis revealed significantly increased accumulation of inflammatory macrophages in hearts of LPS-treated KO mice. Accordingly, ablation of Sectm1a remarkably increased inflammatory cytokines levels both in vitro [from bone marrow-derived macrophages (BMDMs)] and in vivo (in serum and myocardium) after LPS challenge. RNA-sequencing results and bioinformatics analyses showed that the most significantly down-regulated genes in KO-BMDMs were modulated by LXRα, a nuclear receptor with robust anti-inflammatory activity in macrophages. Indeed, we identified that the nuclear translocation of LXRα was disrupted in KO-BMDMs when treated with GW3965 (LXR agonist), resulting in higher levels of inflammatory cytokines, compared to GW3965-treated WT-cells. Furthermore, using chronic inflammation model of high-fat diet (HFD) feeding, we observed that infiltration of inflammatory monocytes/macrophages into KO-hearts were greatly increased and accordingly, worsened cardiac function, compared to WT-HFD controls.
Conclusion
This study defines Sectm1a as a new regulator of inflammatory-induced cardiac dysfunction through modulation of LXRα signalling in macrophages. Our data suggest that augmenting Sectm1a activity may be a potential therapeutic approach to resolve inflammation and associated cardiac dysfunction.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Feb 2021; 117:890-902

Macrophage lineages in heart valve development and disease.

Kim AJ, Xu N, Yutzey KE
Heterogeneous macrophage lineages are present in the aortic and mitral valves of the heart during development and disease. These populations include resident macrophages of embryonic origins and recruited monocyte-derived macrophages prevalent in disease. Soon after birth, macrophages from haematopoietic lineages are recruited to the heart valves, and bone marrow transplantation studies in mice demonstrate that haematopoietic-derived macrophages continue to invest adult valves. During myxomatous heart valve disease, monocyte-derived macrophages are recruited to the heart valves and they contribute to valve degeneration in a mouse model of Marfan syndrome. Here, we review recent studies of macrophage lineages in heart valve development and disease with discussion of clinical significance and therapeutic applications.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Feb 2021; 117:663-673

MTMR4 SNVs modulate ion channel degradation and clinical severity in congenital long QT syndrome: insights in the mechanism of action of protective modifier genes.

Lee YK, Sala L, Mura M, Rocchetti M, ... Tse HF, Gnecchi M
Aims
In long QT syndrome (LQTS) patients, modifier genes modulate the arrhythmic risk associated with a disease-causing mutation. Their recognition can improve risk stratification and clinical management, but their discovery represents a challenge. We tested whether a cellular-driven approach could help to identify new modifier genes and especially their mechanism of action.
Methods and results
We generated human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM) from two patients carrying the same KCNQ1-Y111C mutation, but presenting opposite clinical phenotypes. We showed that the phenotype of the iPSC-CMs derived from the symptomatic patient is due to impaired trafficking and increased degradation of the mutant KCNQ1 and wild-type human ether-a-go-go-related gene. In the iPSC-CMs of the asymptomatic (AS) patient, the activity of an E3 ubiquitin-protein ligase (Nedd4L) involved in channel protein degradation was reduced and resulted in a decreased arrhythmogenic substrate. Two single-nucleotide variants (SNVs) on the Myotubularin-related protein 4 (MTMR4) gene, an interactor of Nedd4L, were identified by whole-exome sequencing as potential contributors to decreased Nedd4L activity. Correction of these SNVs by CRISPR/Cas9 unmasked the LQTS phenotype in AS cells. Importantly, the same MTMR4 variants were present in 77% of AS Y111C mutation carriers of a separate cohort. Thus, genetically mediated interference with Nedd4L activation seems associated with protective effects.
Conclusion
Our finding represents the first demonstration of the cellular mechanism of action of a protective modifier gene in LQTS. It provides new clues for advanced risk stratification and paves the way for the design of new therapies targeting this specific molecular pathway.

© The Author(s) 2020. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 21 Feb 2021; 117:767-779

Aldosterone-induced hypertension is sex-dependent, mediated by T cells and sensitive to GPER activation.

Dinh QN, Vinh A, Kim HA, Saini N, ... Drummond GR, Sobey CG
Aims
The G protein-coupled estrogen receptor 1 (GPER) may modulate some effects of aldosterone. In addition, G-1 (a GPER agonist) can lower blood pressure (BP) and promote T cell-mediated anti-inflammatory responses. This study aimed to test the effects of G-1 and G-15 (a GPER antagonist) on aldosterone-induced hypertension in mice and to examine the cellular mechanisms involved.
Methods and results
C57Bl/6 (wild-type, WT), RAG1-deficient and GPER-deficient mice were infused with vehicle, aldosterone (0.72 mg/kg/day S.C. plus 0.9% NaCl for drinking) ± G-1 (0.03 mg/kg/day S.C.) ± G-15 (0.3 mg/kg/day S.C.) for 14 days. G-1 attenuated aldosterone-induced hypertension in male WT but not male GPER-deficient mice. G-15 alone did not alter hypertension but it prevented the anti-hypertensive effect of G-1. In intact female WT mice, aldosterone-induced hypertension was markedly delayed and suppressed compared with responses in males, with BP remaining unchanged until after Day 7. In contrast, co-administration of aldosterone and G-15 fully increased BP within 7 days in WT females. Similarly, aldosterone robustly increased BP by Day 7 in ovariectomized WT females, and in both sexes of GPER-deficient mice. Whereas aldosterone had virtually no effect on BP in RAG1-deficient mice, adoptive transfer of T cells from male WT or male GPER-deficient mice into male RAG1-deficient mice restored the pressor response to aldosterone. This pressor effect could be attenuated by G-1 in RAG1-deficient mice that were reconstituted with either WT or GPER-deficient T cells, suggesting that G-1 does not act via T cells to lower BP.
Conclusion
Our findings indicate that although aldosterone-induced hypertension is largely mediated by T cells, it can be attenuated by activation of GPER on non-T cells, which accounts for the sex difference in sensitivity to the pressor effect.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Feb 2021; 117:960-970

Non-coding RNA therapeutics for cardiac regeneration.

Braga L, Ali H, Secco I, Giacca M
A growing body of evidence indicates that cardiac regeneration after myocardial infarction can be achieved by stimulating the endogenous capacity of cardiomyocytes (CMs) to replicate. This process is controlled, both positively and negatively, by a large set of non-coding RNAs (ncRNAs). Some of the microRNAs (miRNAs) that can stimulate CM proliferation is expressed in embryonic stem cells and is required to maintain pluripotency (e.g. the miR-302∼367 cluster). Others also govern the proliferation of different cell types, including cancer cells (e.g. the miR-17∼92 cluster). Additional miRNAs were discovered through systematic screenings (e.g. miR-199a-3p and miR-590-3p). Several miRNAs instead suppress CM proliferation and are involved in the withdrawal of CMs from the cell cycle after birth (e.g. the let-7 and miR-15 families). Similar regulatory roles on CM proliferation are also exerted by a few long ncRNAs. This body of information has obvious therapeutic implications, as miRNAs with activator function or short antisense oligonucleotides against inhibitory miRNAs or lncRNAs can be administered to stimulate cardiac regeneration. Expression of miRNAs can be achieved by gene therapy using adeno-associated vectors, which transduce CMs with high efficiency. More effective and safer for therapeutic purposes, small nucleic acid therapeutics can be obtained as chemically modified, synthetic molecules, which can be administered through lipofection or inclusion in lipid or polymer nanoparticles for efficient cardiac delivery. The notion that it is possible to reprogramme CMs into a regenerative state and that this property can be enhanced by ncRNA therapeutics remains exciting, however extensive experimentation in large mammals and rigorous assessment of safety are required to advance towards clinical application.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Feb 2021; 117:674-693

Ryanodine receptor subtypes regulate Ca2+ sparks/spontaneous transient outward currents and myogenic tone of uterine arteries in pregnancy.

Song R, Hu XQ, Romero M, Holguin MA, ... Wilson SM, Zhang L
Aims
Our recent study demonstrated that increased Ca2+ sparks and spontaneous transient outward currents (STOCs) played an important role in uterine vascular tone and haemodynamic adaptation to pregnancy. The present study examined the role of ryanodine receptor (RyR) subtypes in regulating Ca2+ sparks/STOCs and myogenic tone in uterine arterial adaptation to pregnancy.
Methods and results
Uterine arteries isolated from non-pregnant and near-term pregnant sheep were used in the present study. Pregnancy increased the association of α and β1 subunits of large-conductance Ca2+-activated K+ (BKCa) channels and enhanced the co-localization of RyR1 and RyR2 with the β1 subunit in the uterine artery. In contrast, RyR3 was not co-localized with BKCa β1 subunit. Knockdown of RyR1 or RyR2 in uterine arteries of pregnant sheep downregulated the β1 but not α subunit of the BKCa channel and decreased the association of α and β1 subunits. Unlike RyR1 and RyR2, knockdown of RyR3 had no significant effect on either expression or association of BKCa subunits. In addition, knockdown of RyR1 or RyR2 significantly decreased Ca2+ spark frequency, suppressed STOCs frequency and amplitude, and increased pressure-dependent myogenic tone in uterine arteries of pregnant animals. RyR3 knockdown did not affect Ca2+ sparks/STOCs and myogenic tone in the uterine artery.
Conclusion
Together, the present study demonstrates a novel mechanistic paradigm of RyR subtypes in the regulation of Ca2+ sparks/STOCs and uterine vascular tone, providing new insights into the mechanisms underlying uterine vascular adaptation to pregnancy.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Feb 2021; 117:792-804

The European/International Fibromuscular Dysplasia Registry and Initiative (FEIRI)-clinical phenotypes and their predictors based on a cohort of 1000 patients.

Pappaccogli M, Di Monaco S, Warchoł-Celińska E, Lorthioir A, ... European/International FMD Registry and Initiative (FEIRI), and the Working Group ‘Hypertension and the Kidney’ of the European Society of Hypertension (ESH)
Aims
Since December 2015, the European/International Fibromuscular Dysplasia (FMD) Registry enrolled 1022 patients from 22 countries. We present their characteristics according to disease subtype, age and gender, as well as predictors of widespread disease, aneurysms and dissections.
Methods and results
All patients diagnosed with FMD (string-of-beads or focal stenosis in at least one vascular bed) based on computed tomography angiography, magnetic resonance angiography, and/or catheter-based angiography were eligible. Patients were predominantly women (82%) and Caucasians (88%). Age at diagnosis was 46 ± 16 years (12% ≥65 years old), 86% were hypertensive, 72% had multifocal, and 57% multivessel FMD. Compared to patients with multifocal FMD, patients with focal FMD were younger, more often men, had less often multivessel FMD but more revascularizations. Compared to women with FMD, men were younger, had more often focal FMD and arterial dissections. Compared to younger patients with FMD, patients ≥65 years old had more often multifocal FMD, lower estimated glomerular filtration rate and more atherosclerotic lesions. Independent predictors of multivessel FMD were age at FMD diagnosis, stroke, multifocal subtype, presence of aneurysm or dissection, and family history of FMD. Predictors of aneurysms were multivessel and multifocal FMD. Predictors of dissections were age at FMD diagnosis, male gender, stroke, and multivessel FMD.
Conclusions
The European/International FMD Registry allowed large-scale characterization of distinct profiles of patients with FMD and, more importantly, identification of a unique set of independent predictors of widespread disease, aneurysms and dissections, paving the way for targeted screening, management, and follow-up of FMD.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Feb 2021; 117:950-959

Targeting mitochondrial fission as a potential therapeutic for abdominal aortic aneurysm.

Cooper HA, Cicalese S, Preston KJ, Kawai T, ... Rizzo V, Eguchi S
Aims
Angiotensin II (AngII) is a potential contributor to the development of abdominal aortic aneurysm (AAA). In aortic vascular smooth muscle cells (VSMCs), exposure to AngII induces mitochondrial fission via dynamin-related protein 1 (Drp1). However, pathophysiological relevance of mitochondrial morphology in AngII-associated AAA remains unexplored. Here, we tested the hypothesis that mitochondrial fission is involved in the development of AAA.
Methods and results
Immunohistochemistry was performed on human AAA samples and revealed enhanced expression of Drp1. In C57BL6 mice treated with AngII plus β-aminopropionitrile, AAA tissue also showed an increase in Drp1 expression. A mitochondrial fission inhibitor, mdivi1, attenuated AAA size, associated aortic pathology, Drp1 protein induction, and mitochondrial fission but not hypertension in these mice. Moreover, western-blot analysis showed that induction of matrix metalloproteinase-2, which precedes the development of AAA, was blocked by mdivi1. Mdivi1 also reduced the development of AAA in apolipoprotein E-deficient mice infused with AngII. As with mdivi1, Drp1+/- mice treated with AngII plus β-aminopropionitrile showed a decrease in AAA compared to control Drp1+/+ mice. In abdominal aortic VSMCs, AngII induced phosphorylation of Drp1 and mitochondrial fission, the latter of which was attenuated with Drp1 silencing as well as mdivi1. AngII also induced vascular cell adhesion molecule-1 expression and enhanced leucocyte adhesion and mitochondrial oxygen consumption in smooth muscle cells, which were attenuated with mdivi1.
Conclusion
These data indicate that Drp1 and mitochondrial fission play salient roles in AAA development, which likely involves mitochondrial dysfunction and inflammatory activation of VSMCs.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Feb 2021; 117:971-982

Ex vivo Ikkβ ablation rescues the immunopotency of mesenchymal stromal cells from diabetics with advanced atherosclerosis.

Kizilay Mancini O, Huynh DN, Menard L, Shum-Tim D, ... Colmegna I, Servant MJ
Aims
Diabetes is a conventional risk factor for atherosclerotic cardiovascular disease and myocardial infarction (MI) is the most common cause of death among these patients. Mesenchymal stromal cells (MSCs) in patients with type 2 diabetes mellitus (T2DM) and atherosclerosis have impaired ability to suppress activated T-cells (i.e. reduced immunopotency). This is mediated by an inflammatory shift in MSC-secreted soluble factors (i.e. pro-inflammatory secretome) and can contribute to the reduced therapeutic effects of autologous T2DM and atherosclerosis-MSC post-MI. The signalling pathways driving the altered secretome of atherosclerosis- and T2DM-MSC are unknown. Specifically, the effect of IκB kinase β (IKKβ) modulation, a key regulator of inflammatory responses, on the immunopotency of MSCs from T2DM patients with advanced atherosclerosis has not been studied.
Methods and results
MSCs were isolated from adipose tissue obtained from patients with (i) atherosclerosis and T2DM (atherosclerosis+T2DM MSCs, n = 17) and (ii) atherosclerosis without T2DM (atherosclerosis MSCs, n = 17). MSCs from atherosclerosis+T2DM individuals displayed an inflammatory senescent phenotype and constitutively expressed active forms of effectors of the canonical IKKβ nuclear factor-κB transcription factors inflammatory pathway. Importantly, this constitutive pro-inflammatory IKKβ signature resulted in an altered secretome and impaired in vitro immunopotency and in vivo healing capacity in an acute MI model. Notably, treatment with a selective IKKβ inhibitor or IKKβ knockdown (KD) (clustered regularly interspaced short palindromic repeats/Cas9-mediated IKKβ KD) in atherosclerosis+T2DM MSCs reduced the production of pro-inflammatory secretome, increased survival, and rescued their immunopotency both in vitro and in vivo.
Conclusions
Constitutively active IKKβ reduces the immunopotency of atherosclerosis+T2DM MSC by changing their secretome composition. Modulation of IKKβ in atherosclerosis+T2DM MSCs enhances their myocardial repair ability.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Feb 2021; 117:756-766

Human influenza A virus causes myocardial and cardiac-specific conduction system infections associated with early inflammation and premature death.

Filgueiras-Rama D, Vasilijevic J, Jalife J, Noujaim SF, ... Nieto A, Falcon A
Aims
Human influenza A virus (hIAV) infection is associated with important cardiovascular complications, although cardiac infection pathophysiology is poorly understood. We aimed to study the ability of hIAV of different pathogenicity to infect the mouse heart, and establish the relationship between the infective capacity and the associated in vivo, cellular and molecular alterations.
Methods and results
We evaluated lung and heart viral titres in mice infected with either one of several hIAV strains inoculated intranasally. 3D reconstructions of infected cardiac tissue were used to identify viral proteins inside mouse cardiomyocytes, Purkinje cells, and cardiac vessels. Viral replication was measured in mouse cultured cardiomyocytes. Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were used to confirm infection and study underlying molecular alterations associated with the in vivo electrophysiological phenotype. Pathogenic and attenuated hIAV strains infected and replicated in cardiomyocytes, Purkinje cells, and hiPSC-CMs. The infection was also present in cardiac endothelial cells. Remarkably, lung viral titres did not statistically correlate with viral titres in the mouse heart. The highly pathogenic human recombinant virus PAmut showed faster replication, higher level of inflammatory cytokines in cardiac tissue and higher viral titres in cardiac HL-1 mouse cells and hiPSC-CMs compared with PB2mut-attenuated virus. Correspondingly, cardiac conduction alterations were especially pronounced in PAmut-infected mice, associated with high mortality rates, compared with PB2mut-infected animals. Consistently, connexin43 and NaV1.5 expression decreased acutely in hiPSC-CMs infected with PAmut virus. YEM1L protease also decreased more rapidly and to lower levels in PAmut-infected hiPSC-CMs compared with PB2mut-infected cells, consistent with mitochondrial dysfunction. Human IAV infection did not increase myocardial fibrosis at 4-day post-infection, although PAmut-infected mice showed an early increase in mRNAs expression of lysyl oxidase.
Conclusion
Human IAV can infect the heart and cardiac-specific conduction system, which may contribute to cardiac complications and premature death.

© The Author(s) 2020. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 21 Feb 2021; 117:876-889

BET bromodomain-containing epigenetic reader proteins regulate vascular smooth muscle cell proliferation and neointima formation.

Dutzmann J, Haertlé M, Daniel JM, Kloss F, ... Sedding DG, Gegel S
Aims
Recent studies revealed that the bromodomain and extra-terminal (BET) epigenetic reader proteins resemble key regulators in the underlying pathophysiology of cancer, diabetes, or cardiovascular disease. However, whether they also regulate vascular remodelling processes by direct effects on vascular cells is unknown. In this study, we investigated the effects of the BET proteins on human smooth muscle cell (SMC) function in vitro and neointima formation in response to vascular injury in vivo.
Methods and results
Selective inhibition of BETs by the small molecule (+)-JQ1 dose-dependently reduced proliferation and migration of SMCs without apoptotic or toxic effects. Flow cytometric analysis revealed a cell cycle arrest in the G0/G1 phase in the presence of (+)-JQ1. Microarray- and pathway analyses revealed a substantial transcriptional regulation of gene sets controlled by the Forkhead box O (FOXO1)1-transcription factor. Silencing of the most significantly regulated FOXO1-dependent gene, CDKN1A, abolished the antiproliferative effects. Immunohistochemical colocalization, co-immunoprecipitation, and promoter-binding ELISA assay data confirmed that the BET protein BRD4 directly binds to FOXO1 and regulates FOXO1 transactivational capacity. In vivo, local application of (+)-JQ1 significantly attenuated SMC proliferation and neointimal lesion formation following wire-induced injury of the femoral artery in C57BL/6 mice.
Conclusion
Inhibition of the BET-containing protein BRD4 after vascular injury by (+)-JQ1 restores FOXO1 transactivational activity, subsequent CDKN1A expression, cell cycle arrest and thus prevents SMC proliferation in vitro and neointima formation in vivo. Inhibition of BET epigenetic reader proteins might thus represent a promising therapeutic strategy to prevent adverse vascular remodelling.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Feb 2021; 117:850-862

Human-induced pluripotent stem cells for modelling metabolic perturbations and impaired bioenergetics underlying cardiomyopathies.

Ramachandra CJA, Chua J, Cong S, Kp MMJ, ... Wu JC, Hausenloy DJ
Normal cardiac contractile and relaxation functions are critically dependent on a continuous energy supply. Accordingly, metabolic perturbations and impaired mitochondrial bioenergetics with subsequent disruption of ATP production underpin a wide variety of cardiac diseases, including diabetic cardiomyopathy, dilated cardiomyopathy, hypertrophic cardiomyopathy, anthracycline cardiomyopathy, peripartum cardiomyopathy, and mitochondrial cardiomyopathies. Crucially, there are no specific treatments for preventing the onset or progression of these cardiomyopathies to heart failure, one of the leading causes of death and disability worldwide. Therefore, new treatments are needed to target the metabolic disturbances and impaired mitochondrial bioenergetics underlying these cardiomyopathies in order to improve health outcomes in these patients. However, investigation of the underlying mechanisms and the identification of novel therapeutic targets have been hampered by the lack of appropriate animal disease models. Furthermore, interspecies variation precludes the use of animal models for studying certain disorders, whereas patient-derived primary cell lines have limited lifespan and availability. Fortunately, the discovery of human-induced pluripotent stem cells has provided a promising tool for modelling cardiomyopathies via human heart tissue in a dish. In this review article, we highlight the use of patient-derived iPSCs for studying the pathogenesis underlying cardiomyopathies associated with metabolic perturbations and impaired mitochondrial bioenergetics, as the ability of iPSCs for self-renewal and differentiation makes them an ideal platform for investigating disease pathogenesis in a controlled in vitro environment. Continuing progress will help elucidate novel mechanistic pathways, and discover novel therapies for preventing the onset and progression of heart failure, thereby advancing a new era of personalized therapeutics for improving health outcomes in patients with cardiomyopathy.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Feb 2021; 117:694-711

Quantifying technical confounders in microbiome studies.

Bartolomaeus TUP, Birkner T, Bartolomaeus H, Löber U, ... Markó L, Forslund SK
Aims
Recent technical developments have allowed the study of the human microbiome to accelerate at an unprecedented pace. Methodological differences may have considerable impact on the results obtained. Thus, we investigated how different storage, isolation, and DNA extraction methods can influence the characterization of the intestinal microbiome, compared to the impact of true biological signals such as intraindividual variability, nutrition, health, and demographics.
Methods and results
An observative cohort study in 27 healthy subjects was performed. Participants were instructed to collect stool samples twice spaced by a week, using six different methods (naive and Zymo DNA/RNA Shield on dry ice, OMNIgene GUT, RNALater, 95% ethanol, Zymo DNA/RNA Shield at room temperature). DNA extraction from all samples was performed comparatively using QIAamp Power Fecal and ZymoBIOMICS DNA Kits. 16S rRNA sequencing of the gut microbiota as well as qPCRs were performed on the isolated DNA. Metrics included alpha diversity as well as multivariate and univariate comparisons of samples, controlling for covariate patterns computationally. Interindividual differences explained 7.4% of overall microbiome variability, whereas the choice of DNA extraction method explained a further 5.7%. At phylum level, the tested kits differed in their recovery of Gram-positive bacteria, which is reflected in a significantly skewed enterotype distribution.
Conclusion
DNA extraction methods had the highest impact on observed microbiome variability, and were comparable to interindividual differences, thus may spuriously mimic the microbiome signatures of various health and nutrition factors. Conversely, collection methods had a relatively small influence on microbiome composition. The present study provides necessary insight into the technical variables which can lead to divergent results from seemingly similar study designs. We anticipate that these results will contribute to future efforts towards standardization of microbiome quantification procedures in clinical research.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Feb 2021; 117:863-875

Loss of SIRT1 in diabetes accelerates DNA damage-induced vascular calcification.

Bartoli-Leonard F, Wilkinson FL, Schiro A, Serracino Inglott F, Alexander MY, Weston R
Aims
Vascular calcification is a recognized predictor of cardiovascular risk in the diabetic patient, with DNA damage and accelerated senescence linked to oxidative stress-associated pathological calcification. Having previously shown that systemic SIRT1 is reduced in diabetes, the aim was to establish whether SIRT1 is protective against a DNA damage-induced senescent and calcified phenotype in diabetic vascular smooth muscle cells (vSMCs).
Methods and results
Immunohistochemistry revealed decreased SIRT1 and increased DNA damage marker expression in diabetic calcified arteries compared to non-diabetic and non-calcified controls, strengthened by findings that vSMCs isolated from diabetic patients show elevated DNA damage and senescence, assessed by the Comet assay and telomere length. Hyperglycaemic conditions were used and induced DNA damage and enhanced senescence in vSMCs in vitro. Using H2O2 as a model of oxidative stress-induced DNA damage, pharmacological activation of SIRT1 reduced H2O2 DNA damage-induced calcification, prevented not only DNA damage, as shown by reduced comet tail length, but also decreased yH2AX foci formation, and attenuated calcification. While Ataxia Telanglectasia Mutated (ATM) expression was reduced following DNA damage, in contrast, SIRT1 activation significantly increased ATM expression, phosphorylating both MRE11 and NBS1, thus allowing formation of the MRN complex and increasing activation of the DNA repair pathway.
Conclusion
DNA damage-induced calcification is accelerated within a diabetic environment and can be attenuated in vitro by SIRT1 activation. This occurs through enhancement of the MRN repair complex within vSMCs and has therapeutic potential within the diabetic patient.

© The Author(s) 2020. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 21 Feb 2021; 117:836-849

The long and winding road of cardiomyocyte maturation.

Maroli G, Braun T
Knowledge about the molecular mechanisms regulating cardiomyocyte (CM) proliferation and differentiation has increased exponentially in recent years. Such insights together with the availability of more efficient protocols for generation of CMs from induced pluripotent stem cells (iPSCs) have raised expectations for new therapeutic strategies to treat congenital and non-congenital heart diseases. However, the poor regenerative potential of the postnatal heart and the incomplete maturation of iPSC-derived CMs represent important bottlenecks for such therapies in future years. CMs undergo dramatic changes at the doorstep between prenatal and postnatal life, including terminal cell cycle withdrawal, change in metabolism, and further specialization of the cellular machinery required for high-performance contraction. Here, we review recent insights into pre- and early postnatal developmental processes that regulate CM maturation, laying specific focus on genetic and metabolic pathways that control transition of CMs from the embryonic and perinatal to the fully mature adult CM state. We recapitulate the intrinsic features of CM maturation and highlight the importance of external factors, such as energy substrate availability and endocrine regulation in shaping postnatal CM development. We also address recent approaches to enhance maturation of iPSC-derived CMs in vitro, and summarize new discoveries that might provide useful tools for translational research on repair of the injured human heart.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Feb 2021; 117:712-726

Heart regeneration: beyond new muscle and vessels.

Sayers JR, Riley PR
The most striking consequence of a heart attack is the loss of billions of heart muscle cells, alongside damage to the associated vasculature. The lost cardiovascular tissue is replaced by scar formation, which is non-functional and results in pathological remodelling of the heart and ultimately heart failure. It is, therefore, unsurprising that the heart regeneration field has centred efforts to generate new muscle and blood vessels through targeting cardiomyocyte proliferation and angiogenesis following injury. However, combined insights from embryological studies and regenerative models, alongside the adoption of -omics technology, highlight the extensive heterogeneity of cell types within the forming or re-forming heart and the significant crosstalk arising from non-muscle and non-vessel cells. In this review, we focus on the roles of fibroblasts, immune, conduction system, and nervous system cell populations during heart development and we consider the latest evidence supporting a function for these diverse lineages in contributing to regeneration following heart injury. We suggest that the emerging picture of neurologically, immunologically, and electrically coupled cell function calls for a wider-ranging combinatorial approach to heart regeneration.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected]

Cardiovasc Res: 21 Feb 2021; 117:727-742