Arterial myeloperoxidase in the detection and treatment of vulnerable atherosclerotic plaque: a new dawn for an old light.

Nadel J, Jabbour A, Stocker R
Intracellular myeloperoxidase (MPO) plays a specific role in the innate immune response; however, upon release into the extracellular space in the setting of inflammation, drives oxidative tissue injury. Extracellular MPO has recently been shown to be abundant in unstable atheroma and causally linked to plaque destabilization, erosion, and rupture, identifying it as a potential target for the surveillance and treatment of vulnerable atherosclerosis. Through the compartmentalization of MPO\'s protective and deleterious effects, extracellular MPO can be selectively detected using non-invasive molecular imaging and targeted by burgeoning pharmacotherapies. Given its causal relationship to plaque destabilization coupled with an ability to preserve its beneficial properties, MPO is potentially a superior translational inflammatory target compared with other immunomodulatory therapies and imaging biomarkers utilized to date. This review explores the role of MPO in plaque destabilization and provides insights into how it can be harnessed in the management of patients with vulnerable atherosclerotic plaque.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 19 May 2022; epub ahead of print

Myeloid CD40 deficiency reduces atherosclerosis by impairing macrophages\' transition into a pro-inflammatory state.

Bosmans LA, van Tiel CM, Aarts SABM, Willemsen L, ... Shami A, Lutgens E
Aims
CD40 and its ligand, CD40L, play a critical role in driving atherosclerotic plaque development. Disrupted CD40-signaling reduces experimental atherosclerosis and induces a favourable stable plaque phenotype. We recently showed that small molecule-based inhibition of CD40-TNF Receptor Associated Factor-6 interactions attenuates atherosclerosis in hyperlipidaemic mice via macrophage-driven mechanisms. The present study aims to detail the function of myeloid CD40 in atherosclerosis using myeloid-specific CD40-deficient mice.
Method and results
Cd40flox/flox and LysM-cre Cd40flox/flox mice on an Apoe-/- background were generated (CD40wt and CD40mac-/-, respectively). Atherosclerotic lesion size, as well as plaque macrophage content, were reduced in CD40mac-/- compared to CD40wt mice and their plaques displayed a reduction in necrotic core size. Transcriptomics analysis of the CD40mac-/- atherosclerotic aorta revealed downregulated pathways of immune pathways and inflammatory responses.Loss of CD40 in macrophages changed the representation of aortic macrophage subsets. Mass cytometry analysis revealed a higher content of a subset of alternative or resident-like CD206 + CD209b- macrophages in the atherosclerotic aorta of CD40mac-/- compared to CD40wt mice. RNA-sequencing of bone marrow-derived macrophages (BMDMs) of CD40mac-/- mice demonstrated upregulation of genes associated with alternatively activated macrophages (including Folr2, Thbs1, Sdc1 and Tns1).
Conclusions
We here show that absence of CD40 signalling in myeloid cells reduces atherosclerosis and limits systemic inflammation by preventing a shift in macrophage polarization towards pro-inflammatory states. Our study confirms the merit of macrophage-targeted inhibition of CD40 as a valuable therapeutic strategy to combat atherosclerosis.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology.

Cardiovasc Res: 19 May 2022; epub ahead of print

Ryanodine receptor 2 (RYR2) dysfunction activates the unfolded protein response and perturbs cardiomyocyte maturation.

Guo Y, Cao Y, Jardin BD, Zhang X, ... Dong E, Pu WT
Aims
Calcium handling capacity is a major gauge of cardiomyocyte maturity. Ryanodine receptor 2 (RYR2) is the predominant calcium channel that releases calcium from the sarcoplasmic reticulum/endoplasmic reticulum (SR/ER) to activate cardiomyocyte contraction. Although RYR2 was previously implied as a key regulator of cardiomyocyte maturation, the mechanisms remain unclear. The aim of this study is to solve this problem.
Methods and results
We performed Cas9/AAV9-mediated somatic mutagenesis (CASAAV) to knockout RYR2 specifically in cardiomyocytes in mice. We conducted a genetic mosaic analysis to dissect the cell-autonomous function of RYR2 during cardiomyocyte maturation. We found that RYR2 depletion triggered ultrastructural and transcriptomic defects relevant to cardiomyocyte maturation. These phenotypes were associated with the drastic activation of ER stress pathways. The ER stress alleviator tauroursodeoxycholic acid (TUDCA) partially rescued the defects in RYR2-depleted cardiomyocytes. Overexpression of ATF4, a key ER stress transcription factor, recapitulated defects in RYR2-depleted cells. Integrative analysis of RNA-Seq and bioChIP-Seq data revealed that protein biosynthesis-related genes are the major direct downstream targets of ATF4.
Conclusions
RYR2-regulated ER homeostasis is essential for cardiomyocyte maturation. Severe ER stress perturbs cardiomyocyte maturation primarily through ATF4 activation. The major downstream effector genes of ATF4 are related to protein biosynthesis.
Translational perspective
Dysfunctional calcium handling is a major factor contributing to cardiac pathogenesis, but the molecular mechanisms remain unclear. This study uncovered RYR2 as a new regulator of ER stress and cardiomyocyte maturation, providing significant insights to guide the development of therapeutic approaches to control cardiac pathogenesis. Because cardiomyocyte maturation is a major bottleneck in translational medicine using stem cell-derived cardiomyocytes, this study also pointed out RYR2 and ER homeostasis as potential targets to manipulate the maturity of stem cell-derived cardiomyocytes.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 16 May 2022; epub ahead of print

Mortality prediction of retinal vessel diameters and function in a long-term follow-up of hemodialysis patients.

Günthner R, Streese L, Angermann S, Lorenz G, ... Hanssen H, Schmaderer C
Aim
Retinal vessel diameters are candidate biomarkers of mortality prediction in large population-based studies. We aimed to investigate the predictive value of retinal vessel diameters and flicker-induced retinal arteriolar and venular dilation on all-cause mortality in long-term follow-up of hemodialysis patients.
Methods and results
Retinal vessel diameters as well as maximum arteriolar (aMax) and venular dilation (vMax) were investigated in 275 and 214 hemodialysis patients, respectively. Patients were observed in a long-term follow-up for a median period of 73 months. 36% (76/214) and 41% (113/275) of patients died. Arteriolar and venular diameters were 175 ± 19 µm and 208 ± 20 µm, respectively. Median aMax and vMax were 1.6 [0.3-3.3]% and 3.2 [2.0-5.1]%. Patients within the lowest tertile of vMax showed lower 5-year survival rates compared to the highest tertile (50.6% vs 82.1%) and also exhibited a higher incidence of infection-related deaths (21.7% vs 4.0%). Univariate hazard ratio per SD increase of vMax for all-cause mortality was 0.69 [0.54; 0.88] and was even more pronounced for infection-related mortality (HR 0.53 [0.33; 0.83]). Regarding all-cause mortality, multivariate adjustment for eight non-retinal mortality predictors including IL-6 did not attenuate the hazard ratio relevantly (0.73 [0.54; 0.98]). Arteriolar and venular diameters did not predict all-cause, nor cardiovascular and infection-related mortality.
Conclusions
Long-term follow-up of patients on hemodialysis demonstrated the potential of retinal venular dilation capacity for mortality-prediction, which was most pronounced for infection-related mortality. In the same cohort, retinal arteriolar and venular diameters showed no predictive value for hard endpoints. Retinal venular dilation but not arteriolar and venular diameters is a valuable diagnostic biomarker for risk prediction in patients with end-stage renal disease and should be considered for monitoring of critically ill patients.
Translational perspective
Retinal vessel phenotyping has the potential to improve risk stratification of overall cardiovascular risk. Especially, retinal microvascular function improves stratification of disease severity compared to traditional risk assessment in multimorbid patients. Blunted retinal microvascular function is independently associated with higher 5-year mortality rates and higher incidence of infection-related deaths. Retinal vessel analysis as add-on to standard of care has the potential to optimize personalized clinical decision-making and may help guide treatment strategies in the future.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 16 May 2022; epub ahead of print

Spatial transcriptomics unveils ZBTB11 as a regulator of cardiomyocyte degeneration in arrhythmogenic cardiomyopathy.

Boogerd CJ, Lacraz GPA, Vértesy Á, van Kampen SJ, ... Vink A, van Rooij E
Aims
Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiac disorder that is characterized by progressive loss of myocardium that is replaced by fibro-fatty cells, arrhythmias, and sudden cardiac death. While myocardial degeneration and fibro-fatty replacement occur in specific locations, the underlying molecular changes remain poorly characterized. Here we aim to delineate local changes in gene expression to identify new genes and pathways that are relevant for specific remodelling processes occurring during ACM.
Methods and results
Using Tomo-Seq, genome-wide transcriptional profiling with high spatial resolution, we created transmural epicardial to endocardial gene expression atlases of explanted ACM hearts to gain molecular insights into disease-driving processes. This enabled us to link gene expression profiles to the different regional remodelling responses and allowed us to identify genes that are potentially relevant for disease progression. In doing so, we identified distinct gene expression profiles marking regions of cardiomyocyte degeneration and fibro-fatty remodelling and revealed Zinc finger and BTB domain-containing protein 11 (ZBTB11) to be specifically enriched at sites of active fibro-fatty replacement of myocardium. Immunohistochemistry indicated ZBTB11 to be induced in cardiomyocytes flanking fibro-fatty areas, which could be confirmed in multiple cardiomyopathy patients. Forced overexpression of ZBTB11 induced autophagy and cell death-related gene programs in human cardiomyocytes, leading to increased apoptosis.
Conclusions
Our study shows the power of Tomo-Seq to unveil new molecular mechanisms in human cardiomyopathy and uncovers ZBTB11 as a novel driver of cardiomyocyte loss.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology.

Cardiovasc Res: 16 May 2022; epub ahead of print

Targeting DNA damage response in cardiovascular diseases: from pathophysiology to therapeutic implications.

Wu L, Sowers JR, Zhang Y, Ren J
Cardiovascular diseases (CVDs), arise from a complex interplay among genomic, proteomic, and metabolomic abnormalities. Emerging evidence has recently consolidated the presence of robust DNA damage in a variety of cardiovascular disorders. DNA damage triggers a series of cellular responses termed DNA damage response (DDR) including detection of DNA lesions, cell cycle arrest, DNA repair, cellular senescence and apoptosis, in all organ systems including hearts and vasculature. Although transient DDR in response to temporary DNA damage can be beneficial for cardiovascular function, persistent activation of DDR promotes the onset and development of CVDs. Moreover, therapeutic interventions that target DNA damage and DDR have the potential to attenuate cardiovascular dysfunction and improve disease outcome. In this review, we will discuss molecular mechanisms of DNA damage and repair in the onset and development of CVDs, and explore how DDR in specific cardiac cell types contributes to CVDs. Moreover, we will highlight the latest advances regarding the potential therapeutic strategies targeting DNA damage signaling in CVDs.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 16 May 2022; epub ahead of print

An antiplatelet response gene expression signature is associated with bleeding.

Friede KA, Myers RA, Gales J, Zhbannikov I, ... Ginsburg GS, Voora D
Aims
Gene expression biosignatures may hold promise to individualize antiplatelet therapy in conjunction with current guidelines and risk scores. The Aspirin Response Signature (ARS) score is comprised of a weighted sum of correlated, prothrombotic gene transcripts measured in whole blood. In prior work where volunteers were exposed to aspirin 325  mg daily, higher ARS score was associated with lower platelet function; separately, in a clinical cohort of patients, higher ARS scores were associated with increased risk of adverse cardiovascular events. To better understand this apparent paradox, we measured ARS gene expression and score in volunteers to determine aspirin dose-response and ticagrelor relationships with ARS score and separately in patients to assess whether ARS is associated with incident bleeding.
Methods and results
Blood samples were collected from volunteers (N = 188) who were exposed to 4 weeks of daily aspirin 81  mg, daily aspirin 325  mg, and/or twice-daily ticagrelor 90  mg. ARS scores were calculated from whole blood RNA qPCR, and platelet function and protein expression were assessed in platelet-rich plasma. In mixed linear regression models, aspirin 81  mg exposure was not associated with changes in ARS gene expression or score. Aspirin 325  mg exposure resulted in a 6.0% increase in ARS gene expression (p = 7.5 × 10-9 vs. baseline, p = 2.1 × 10-4 vs. aspirin 81  mg) and an increase in expression of platelet proteins corresponding to ARS genes. Ticagrelor exposure resulted in a 30.7% increase in ARS gene expression (p < 1 × 10-10 vs. baseline and each aspirin dose) and ARS score (p = 7.0 × 10-7 vs. baseline, p = 3.6 × 10-6 and 5.59 × 10-4 vs. aspirin 81  mg and 325  mg, respectively). Increases in ARS gene expression or score were associated with the magnitude of platelet inhibition across agents. To assess the association between ARS scores and incident bleeding, ARS scores were calculated in patients undergoing cardiac catheterization (N = 1421), of whom 25.4% experienced bleeding events over a median 6.2 years of follow-up. In a Cox model adjusting for demographics and baseline antithrombotic medication use, patients with ARS scores above the median had a higher risk of incident bleeding (HR 1.26 [95% CI 1.01-1.56], p = 0.038).
Conclusions
The ARS is an Antiplatelet Response Signature which increases in response to greater platelet inhibition due to antiplatelet therapy and may represent a homeostatic mechanism to prevent bleeding. ARS scores could inform future strategies to prevent bleeding while maintaining antiplatelet therapy\'s benefit of ischemic cardiovascular event protection.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 16 May 2022; epub ahead of print

Adenylate cyclase type 9 antagonizes cAMP accumulation and regulates endothelial signaling involved in atheroprotection.

Rautureau Y, Berlatie M, Rivas D, Uy K, ... Rhéaume É, Tardif JC
Aims
The adenylate cyclase type 9 (ADCY9) gene appears to determine atherosclerotic outcomes in patients treated with dalcetrapib. In mice, we recently demonstrated that Adcy9 inactivation potentiates endothelial function and inhibits atherogenesis. The objective of this study was to characterize the contribution of ADCY9 to the regulation of endothelial signaling pathways involved in atherosclerosis.
Methods and results
We show that ADCY9 is expressed in the endothelium of mouse aorta and femoral arteries. We demonstrate that ADCY9 inactivation in cultured endothelial cells paradoxically increases cAMP accumulation in response to the adenylate cyclase activators forskolin and vasoactive intestinal peptide (VIP). Reciprocally, ADCY9 overexpression decreases cAMP production. Using mouse femoral artery arteriography, we show that Adcy9 inactivation potentiates VIP-induced endothelial-dependent vasodilation. Moreover, Adcy9 inactivation reduces mouse atheroma endothelial permeability in different vascular beds. ADCY9 overexpression reduces forskolin-induced phosphorylation of Ser157-vasodilator-stimulated phosphoprotein (VASP) and worsens thrombin-induced fall of RAP1 activity, both leading to increased endothelial permeability. ADCY9 inactivation in thrombin-stimulated human coronary artery endothelial cells results in cAMP accumulation, increases p-Ser157-VASP and inhibits endothelial permeability. MLC2 phosphorylation and actin stress fiber increases in response to thrombin were reduced by ADCY9 inactivation, suggesting actin cystoskeleton regulation. Finally, using the Miles assay, we demonstrate that Adcy9 regulates thrombin-induced endothelial permeability in vivo in normal and atherosclerotic animals.
Conclusion
Adcy9 is expressed in endothelial cells and regulates local cAMP and endothelial functions including permeability relevant to atherogenesis.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 16 May 2022; epub ahead of print

Primary cilia control endothelial permeability by regulating expression and location of junction proteins.

Diagbouga MR, Morel S, Cayron AF, Haemmerli J, ... Bijlenga P, Kwak BR
Aims
Wall shear stress (WSS) determines intracranial aneurysm (IA) development. Polycystic kidney disease (PKD) patients have a high IA incidence and risk of rupture. Dysfunction/absence of primary cilia in PKD endothelial cells (ECs) may impair mechano-transduction of WSS and favour vascular disorders. The molecular links between primary cilia dysfunction and IAs are unknown.
Methods and results
Wild-type and primary cilia-deficient Tg737orpk/orpk arterial ECs were submitted to physiological (30 dynes/cm2) or aneurysmal (2 dynes/cm2) WSS, and unbiased transcriptomics were performed. Tg737orpk/orpk ECs displayed a fivefold increase in the number of WSS-responsive genes compared to wild-type cells. Moreover, we observed a lower trans-endothelial resistance and a higher endothelial permeability, which correlated with disorganized intercellular junctions in Tg737orpk/orpk cells. We identified ZO-1 as a central regulator of primary cilia-dependent endothelial junction integrity. Finally, clinical and histological characteristics of IAs from non-PKD and PKD patients were analysed. IAs in PKD patients were more frequently located in the middle cerebral artery (MCA) territory than in non-PKD patients. IA domes from the MCA of PKD patients appeared thinner with less collagen and reduced endothelial ZO-1 compared with IA domes from non-PKD patients.
Conclusion
Primary cilia dampen the endothelial response to aneurysmal low WSS. In absence of primary cilia, ZO-1 expression levels are reduced, which disorganizes intercellular junctions resulting in increased endothelial permeability. This altered endothelial function may not only contribute to the severity of IA disease observed in PKD patients, but may also serve as a potential diagnostic tool to determine the vulnerability of IAs.

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

Cardiovasc Res: 06 May 2022; 118:1583-1596

Role of oxidative stress in calcific aortic valve disease and its therapeutic implications.

Greenberg HZE, Zhao G, Shah AM, Zhang M
Calcific aortic valve disease (CAVD) is the end result of active cellular processes that lead to the progressive fibrosis and calcification of aortic valve leaflets. In western populations, CAVD is a significant cause of cardiovascular morbidity and mortality, and in the absence of effective drugs, it will likely represent an increasing disease burden as populations age. As there are currently no pharmacological therapies available for preventing, treating, or slowing the development of CAVD, understanding the mechanisms underlying the initiation and progression of the disease is important for identifying novel therapeutic targets. Recent evidence has emerged of an important causative role for reactive oxygen species (ROS)-mediated oxidative stress in the pathophysiology of CAVD, inducing the differentiation of valve interstitial cells into myofibroblasts and then osteoblasts. In this review, we focus on the roles and sources of ROS driving CAVD and consider their potential as novel therapeutic targets for this debilitating condition.

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

Cardiovasc Res: 06 May 2022; 118:1433-1451

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: 06 May 2022; 118:1492-1505

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 signalling 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 AAD by inhibiting VSMC phenotype switching, suggesting that Anxa1 signalling may be a potential target for AAD pharmacological therapy.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.

Cardiovasc Res: 06 May 2022; 118:1564-1582

No sex-related differences in infarct size, no-reflow and protection by ischaemic preconditioning in Göttingen minipigs.

Kleinbongard P, Lieder H, Skyschally A, Heusch G
Aims
Female sex has been proposed to be cardioprotective per se. Studies with myocardial ischaemia/reperfusion and infarct size as endpoint have demonstrated cardioprotection in female, castrated male and male pigs. These studies are difficult to compare, given the different pig strains, models, durations of ischaemia and methods of infarct size quantification. The few studies using both female and male pigs reported no differences in infarct size and cardioprotection. We therefore prospectively compared infarct size in Göttingen minipigs undergoing ischaemia/reperfusion (I/R) without and with ischaemic preconditioning (IPC) between female, castrated male and male pigs.
Methods and results
In a prospective, randomised approach, 28 Göttingen open-chest, anaesthetised minipigs underwent 60 min ischaemia by distal left anterior descending artery (LAD) occlusion and 180 min reperfusion without and with IPC by 3 cycles of 5 min LAD occlusion/10 min reperfusion. Infarct size with I/R was not different between female, castrated male and male pigs (45±8 vs. 45±13 vs. 41±9% area at risk), as was the reduction in infarct size with IPC (25±11 vs. 30±8 vs. 19±10% area at risk). Also, the area of no-reflow was not different between female, castrated male and male pigs with I/R (57±13 vs. 35±7 vs. 47±26% infarct size) or IPC (4±10 vs.12±20 vs. 0±0% infarct size). Phosphorylation of signal transducer and activator of transcription 3 was increased at 10 min reperfusion by IPC but not by I/R to the same extent in female, castrated male and male pigs (198±30 vs. 230±165 vs. 179±107% of baseline).
Conclusion
Our data do not support the notion of sex- or castration-related differences in infarct size, coronary microvascular injury and cardioprotection by ischaemic preconditioning.
Translational perspective
The translation of successful preclinical studies on cardioprotection to the benefit of patients with reperfused myocardial infarction has been difficult. The difficulties have been attributed to confounders such as co-morbidities and co-medications which patients typically have but animals don´t, but also to age and sex. Notably, female sex has been considered as protective per se. We have now, using our established and clinically relevant pig model of reperfused acute myocardial infarction and ischaemic preconditioning as the most robust cardioprotective intervention looked for sex-related differences of infarct size, no-reflow and cardioprotection by ischaemic preconditioning in a prospectively powered approach but found none such difference.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 15 Apr 2022; epub ahead of print

NEUTROPHIL INHIBITION IMPROVES ACUTE INFLAMMATION IN A MURINE MODEL OF VIRAL MYOCARDITIS.

Carai P, Florit González L, Van Bruggen S, Spalart V, ... Jones EAV, Heymans S
Aims
Viral myocarditis (VM) is an inflammatory pathology of the myocardium triggered by a viral infection that may cause sudden death or heart failure, especially in the younger population. Current treatments only stabilise and improve cardiac function without resolving the underlying inflammatory cause. The factors that induce VM to progress to heart failure are still uncertain, but neutrophils have been increasingly associated with the negative evolution of cardiac pathologies. The present study investigates the contribution of neutrophils to VM disease progression in different ways.
Methods and results
In a Coxsackievirus B3- (CVB3) induced mouse model of VM, neutrophils and neutrophil extracellular traps (NETs) were prominent in the acute phase of VM as revealed by ELISA analysis and immunostaining. Anti-Ly6G-mediated neutrophil blockade starting at model induction decreased cardiac necrosis and leukocyte infiltration, preventing monocyte and Ly6CHigh pro-inflammatory macrophage recruitment. Furthermore, genetic peptidylarginine deiminase 4 (PAD4)-dependent NET blockade significantly reduced cardiac damage and leukocyte recruitment, significantly decreasing cardiac monocyte and macrophage presence. Depleting neutrophils with anti-Ly6G antibodies at 7 days post-infection, after the acute phase, did not decrease cardiac inflammation.
Conclusions
Collectively, these results indicate that the repression of neutrophils and the related NET response in the acute phase of VM improves the pathological phenotype by reducing cardiac inflammation.
Translational perspective
Viral myocarditis (VM) is a form of acute heart failure prompted by viral infection that still lacks a specific therapy addressing the cardiac inflammation causing the disease. Increasing evidence suggests that neutrophils actively contribute to the severity of inflammatory and cardiovascular pathologies. Our study demonstrates that inhibition of neutrophil functions in the early phases of VM decreases cardiac damage and inflammation and, therefore, may be considered a very early therapeutic strategy in preventing disease progression.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology.

Cardiovasc Res: 15 Apr 2022; epub ahead of print

Activating P2Y1 receptors improves function in arteries with repressed autophagy.

Cho JM, Park SK, Kwon OS, La Salle DT, ... Trinity JD, Symons JD
Aim
The importance of endothelial cell (EC) autophagy to vascular homeostasis in the context of health and disease is evolving. Earlier we reported that intact EC autophagy is requisite to maintain shear-stress-induced nitric oxide (NO) generation via glycolysis-dependent purinergic signaling to eNOS. Here we illustrate the translational and functional significance of these findings.
Methods and results
First, we assessed translational relevance using older male humans and mice that exhibit blunted EC autophagy and impaired arterial function vs. adult controls. Active hyperemia evoked by RHE elevated radial artery shear rate similarly from baseline in adult and older subjects for 60-min. Compared to baseline, indexes of autophagy initiation, p-eNOSS1177 activation, and NO generation, occurred in radial artery ECs obtained from adult but not older volunteers. Regarding mice, indexes of autophagy and p-eNOSS1177 activation were robust in ECs from adult but not older animals that completed 60-min treadmill-running. Further, 20 dyne • cm2 laminar shear stress x 45-min increased autophagic flux, glycolysis, ATP production, and p-eNOSS1177 in primary arterial ECs obtained from adult but not older mice. Concerning functional relevance, we next questioned whether the inability to initiate EC autophagy, glycolysis, and p-eNOSS1177in vitro precipitates arterial dysfunction ex vivo. Compromised intraluminal flow-mediated vasodilation displayed by arteries from older vs. adult mice was recapitulated in vessels from adult mice by : (i) NO synthase inhibition; (ii) acute autophagy impairment using 3-methyladenine (3-MA); (iii) EC Atg3 depletion (iecAtg3KO mice); (iv) purinergic 2Y1-receptor (P2Y1-R) blockade; and (v) germline depletion of P2Y1-Rs. Importantly, P2Y1-R activation using 2-methylthio-ADP (2-Me-ADP) improved vasodilatory capacity in arteries from : (i) adult mice treated with 3-MA; (ii) adult iecAtg3KO mice; and (iii) older animals with repressed EC autophagy.
Conclusions
Arterial dysfunction concurrent with pharmacological, genetic, and age-associated EC autophagy compromise is improved by activating P2Y1-Rs.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 14 Apr 2022; epub ahead of print

Four decades of experience of prosthetic valve endocarditis reflect a high variety of diverse pathogens.

Oberbach A, Schlichting N, Hagl C, Lehmann S, ... Saha S, Bagaev E
Prosthetic valve endocarditis (PVE) remains a serious condition with a high mortality rate. Precise identification of the PVE-associated pathogen/s and their virulence is essential for successful therapy, and patient survival. The commonly described PVE-associated pathogens are staphylococci, streptococci and enterococci, with Staphylococcus aureus being the most frequently diagnosed species. Furthermore, multi-drug resistance pathogens are increasing in prevalence, and continue to pose new challenges mandating a personalized approach. Blood cultures in combination with echocardiography are the most common methods to diagnose PVE, often being the only indication, it exists. In many cases, the diagnostic strategy recommended in the clinical guidelines does not identify the precise microbial agent and to frequently, false negative blood cultures are reported. Despite the fact that blood culture findings are not always a good indicator of the actual PVE agent in the valve tissue, only a minority of re-operated prostheses are subjected to microbiological diagnostic evaluation. In this review, we focus on the diversity and the complete spectrum of PVE-associated bacterial, fungal and viral pathogens in blood, and prosthetic heart valve, their possible virulence potential, and their challenges in making a microbial diagnosis. We are curious to understand if the unacceptable high mortality of PVE is associated with the high number of negative microbial findings in connection with a possible PVE. Herein, we discuss the possibilities and limits of the diagnostic methods conventionally used and make recommendations for enhanced pathogen identification. We also show possible virulence factors of the most common PVE-associated pathogens and their clinical effects. Based on blood culture, molecular biological diagnostics, and specific valve examination, better derivations for the antibiotic therapy as well as possible preventive intervention can be established in the future.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 14 Apr 2022; epub ahead of print

Long-term trends in the epidemiology of cardiovascular diseases in the UK: Insights from the British Heart Foundation Statistical Compendium.

Cheema KM, Dicks E, Pearson J, Samani NJ
Aims
The British Heart Foundation\'s (BHF) annual statistical compendium is a comprehensive source of accessible epidemiological data in relation to cardiovascular disease (CVD) in the UK. Using datasets with multiple years of data from the compendium we have analysed trends in mortality, morbidity, and treatment for CVD within the UK.
Methods and results
CVD mortality in the UK has consistently declined over recent decades, from 1,045 deaths per 100,000 in 1969, shortly after the BHF was founded, to 255 per 100,000 in 2019. Despite this remarkable improvement, inequalities in CVD mortality persist between the UK nations, for example in 2019 the death rate in Scotland was 326 deaths per 100,000 compared with 246 per 100,000 in England. Improvements in CVD mortality have been paralleled by increased use of primary prevention medications (anti-hypertensives and statins) and interventional procedures. In recent years, progress in mortality outcomes has stalled, probably due to a combination of factors including a rise in risk factors such as obesity and diabetes. In terms of morbidity, CVD remains a significant burden in the UK, accounting for at least 1.18 million hospital admissions and reflect enormous economic burden of CVD, estimated at £19bn in the UK.
Conclusions
Our results highlight the importance of accessible and comprehensive statistics in relation to the burden of CVD and the value of the BHF\'s annual compendium in drawing out conclusions and opportunities for future research. One key area is to improve is the data on which estimation of prevalence is based. There is also a need for ongoing work to better understand the root causes of disparity between socio-economic groups in relation to CVD. One important way to address this will be to improve consistency of reporting of CVD heath data across all nations of the UK. Understanding the causes will inform UK healthcare planning in addition to providing analytical insights that will be applicable in other countries.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 14 Apr 2022; epub ahead of print

Mechanisms, therapeutic implications, and methodological challenges of gut microbiota and cardiovascular diseases: a position paper by the ESC Working Group on Coronary Pathophysiology and Microcirculation.

Tousoulis D, Guzik T, Padro T, Duncker DJ, ... Antoniades C, Crea F
The human gut microbiota is the microbial ecosystem in the small and large intestines of humans. It has been naturally preserved and evolved to play an important role in the function of the gastrointestinal tract and the physiology of its host, protecting from pathogen colonization, and participating in vitamin synthesis, the functions of the immune system, as well as glucose homeostasis and lipid metabolism, among others. Mounting evidence from animal and human studies indicates that the composition and metabolic profiles of the gut microbiota are linked to the pathogenesis of cardiovascular disease, particularly arterial hypertension, atherosclerosis, and heart failure. In this review article, we provide an overview of the function of the human gut microbiota, summarize, and critically address the evidence linking compositional and functional alterations of the gut microbiota with atherosclerosis and coronary artery disease, and discuss the potential of strategies for therapeutically targeting the gut microbiota through various interventions.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 14 Apr 2022; epub ahead of print

Maturation of hiPSC-derived cardiomyocytes promotes adult alternative splicing of SCN5A and reveals changes in sodium current associated with cardiac arrhythmia.

Campostrini G, Kosmidis G, Ward-van Oostwaard D, Davis RP, ... Mummery CL, Bellin M
Aims
Human induced pluripotent stem cell-cardiomyocytes (hiPSC-CMs) are widely used to study arrhythmia-associated mutations in ion channels. Among these, the cardiac sodium channel SCN5A undergoes fetal-to-adult isoform switching around birth. Conventional hiPSC-CM cultures, which are phenotypically fetal, have thus far been unable to capture mutations in adult gene isoforms. Here, we investigated whether tri-cellular cross talk in a three-dimensional cardiac microtissue promoted post-natal SCN5A maturation in hiPSC-CMs.
Methods and results
we derived patient hiPSC-CMs carrying compound mutations in the adult SCN5A exon 6B and exon 4. Electrophysiological properties of patient hiPSC-CMs in monolayer were not altered by the exon 6B mutation compared to isogenic controls since it is not expressed; further, CRISPR/Cas9-mediated excision of the fetal exon 6A did not promote adult SCN5A expression. However, when hiPSC-CMs were matured in three-dimensional cardiac microtissues, SCN5A underwent isoform switch and the functional consequences of the mutation located in exon 6B were revealed. Upregulation of the splicing factor muscleblind-like protein 1 (MBNL1) drove SCN5A post-natal maturation in microtissues since its overexpression in hiPSC-CMs was sufficient to promote exon 6B inclusion, whilst knocking-out MBNL1 failed to foster isoform switch.
Conclusions
Our study shows that (i) the tri-cellular cardiac microtissue promote postnatal SCN5A isoform switch in hiPSC-CMs (ii) adult splicing of SCN5A is driven by MBNL1 in these tissues and (iii) this model can be used for examining postnatal cardiac arrhythmias due to mutations in the exon 6B.
Translational perspective
The cardiac sodium channel is essential for conducting the electrical impulse in the heart. Postnatal alternative splicing regulation causes mutual exclusive inclusion of fetal or adult exons of the corresponding gene, SCN5A. Typically, immature hiPSC-CMs fall short in studying the effect of mutations located in the adult exon. We describe here that an innovative tri-cellular three-dimensional cardiac microtissue culture promotes hiPSC-CMs maturation through upregulation of MBNL1, thus revealing the effect of a pathogenic genetic variant located in the SCN5A adult exon. These results help advancing the use of hiPSC-CMs in studying adult heart disease and for developing personalized medicine applications.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology.

Cardiovasc Res: 08 Apr 2022; epub ahead of print

Intravascular imaging assessment of pharmacotherapies targeting atherosclerosis: advantages and limitations in predicting their prognostic implications.

Tufaro V, Serruys PW, Räber L, Bennett MR, ... Baumbach A, Bourantas C
Intravascular imaging has been often used over the recent years to examine the efficacy of emerging therapies targeting plaque evolution. Serial intravascular ultrasound, optical coherence tomography, or near infrared spectroscopy-intravascular ultrasound studies have allowed us to evaluate the effects of different therapies on plaque burden and morphology, providing unique mechanistic insights about the mode of action of these treatments. Plaque burden reduction, a decrease in necrotic core component or macrophages accumulation - that have been associated with inflammation - and an increase in fibrous cap thickness over fibroatheromas have been used as surrogate endpoints to assess the value of several drugs in inhibiting plaque evolution and improving clinical outcomes. However, some reports have demonstrated weak associations between the effects of novel treatments on coronary atheroma and composition and their prognostic implications. This review examines the value of invasive imaging in assessing pharmacotherapies targeting atherosclerosis. It summarizes the findings of serial intravascular imaging studies assessing the effects of different drugs on atheroma burden and morphology and compares them with the results of large-scale trials evaluating their impact on clinical outcome. Furthermore, it highlights the limited efficacy of established intravascular imaging surrogate endpoints in predicting the prognostic value of these pharmacotherapies and introduces alternative imaging endpoints based on multimodality/hybrid intravascular imaging that may enable more accurate assessment of the athero-protective and prognostic effects of emerging therapies.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 08 Apr 2022; epub ahead of print

Eosinophils protect pressure overload- and β-adrenoreceptor agonist-induced cardiac hypertrophy.

Yang C, Li J, Deng Z, Luo S, ... Guo J, Shi GP
Aims
Blood eosinophil (EOS) counts and EOS cationic protein (ECP) levels associate positively with major cardiovascular disease (CVD) risk factors and prevalence. This study investigates the role of EOS in cardiac hypertrophy.
Methods and results
A retrospective cross-section study of 644 consecutive inpatients with hypertension examined the association between blood EOS counts and cardiac hypertrophy. Pressure overload- and β-adrenoreceptor agonist isoproterenol-induced cardiac hypertrophy was produced in EOS-deficient ΔdblGATA mice. This study revealed positive correlations between blood EOS counts and left ventricular (LV) mass and mass index in humans. ΔdblGATA mice showed exacerbated cardiac hypertrophy and dysfunction, with increased LV wall thickness, reduced LV internal diameter, and increased myocardial cell size, death, and fibrosis. Repopulation of EOS from wild-type mice, but not those from IL4-deficient mice ameliorated cardiac hypertrophy and cardiac dysfunctions. In ΔdblGATA and wild-type mice, administration of EOS cationic protein mEar1 improved cardiac hypertrophy and function. Mechanistic studies demonstrated that EOS expression of IL4, IL13, and mEar1 was essential to control mouse cardiomyocyte hypertrophy and death and cardiac fibroblast TGF-β signaling and fibrotic protein synthesis. Use of human cardiac cells yielded the same results. Human ECP, EOS-derived neurotoxin, human EOS, or murine recombinant mEar1 reduced human cardiomyocyte death and hypertrophy and human cardiac fibroblast TGF-β signaling.
Conclusion
Although blood EOS counts correlated positively with LV mass or LV mass index in humans, this study established a cardioprotective role for EOS IL4 and cationic proteins in cardiac hypertrophy and tested a therapeutic possibility of EOS cationic proteins in this human CVD.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology.

Cardiovasc Res: 08 Apr 2022; epub ahead of print

Aldosterone and cardiovascular diseases.

Parksook WW, Williams GH
Aldosterone\'s role in the kidney and its pathophysiologic actions in hypertension are well known. However, its role or that of its receptor [minieralocorticoid receptor (MR)] in other cardiovascular (CV) disease are less well described. To identify their potential roles in six CV conditions (heart failure, myocardial infarction, atrial fibrillation, stroke, atherosclerosis, and thrombosis), we assessed these associations in four areas: 1) mechanistic studies in rodents and humans; 2) preclinical studies of MR antagonists; 3) clinical trials of MR antagonists; and 4) genetics. The data were acquired from an online search of the National Library of Medicine using the PubMed search engine from January 2011 through June 2021. There were 3702 publications identified with 156 publications meeting our inclusion and exclusion criteria. Data strongly supported an association between heart failure and dysregulated aldosterone/MR. This association is not surprising given aldosterone/MR\'s prominent role in regulating sodium/volume homeostasis. Atrial fibrillation and myocardial infarction are also associated with dysregulated aldosterone/MR, but less strongly. For the most part, the data were insufficient to determine if there was a relationship between atherosclerosis, stroke or thrombosis and aldosterone/MR dysregulation. This review clearly documented an expanding role for aldosterone/MR\'s dysregulation in CV diseases beyond hypertension. How expansive it might be is limited by the currently available data. It is anticipated that with an increased focus on aldosterone/MR\'s potential roles in these diseases, additional clinical and preclinical data will clarify these relationships, thereby, opening approaches to use modulators of aldosterone/MR\'s action to more precisely treat these CV conditions.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 07 Apr 2022; epub ahead of print

Cellular interplay between cardiomyocytes and non-myocytes in diabetic cardiomyopathy.

Phang RJ, Ritchie RH, Hausenloy DJ, Lees JG, Lim SY
Patients with Type 2 diabetes mellitus (T2DM) frequently exhibit a distinctive cardiac phenotype known as diabetic cardiomyopathy. Cardiac complications associated with T2DM include cardiac inflammation, hypertrophy, fibrosis and diastolic dysfunction in the early stages of the disease, which can progress to systolic dysfunction and heart failure. Effective therapeutic options for diabetic cardiomyopathy are limited and often have conflicting results. The lack of effective treatments for diabetic cardiomyopathy is due in part, to our poor understanding of the disease development and progression, as well as a lack of robust and valid preclinical human models that can accurately recapitulate the pathophysiology of the human heart. In addition to cardiomyocytes, the heart contains a heterogeneous population of non-myocytes including fibroblasts, vascular cells, autonomic neurons and immune cells. These cardiac non-myocytes play important roles in cardiac homeostasis and disease, yet the effect of hyperglycaemia and hyperlipidaemia on these cell types are often overlooked in preclinical models of diabetic cardiomyopathy. The advent of human induced pluripotent stem cells provides a new paradigm in which to model diabetic cardiomyopathy as they can be differentiated into all cell types in the human heart. This review will discuss the roles of cardiac non-myocytes and their dynamic intercellular interactions in the pathogenesis of diabetic cardiomyopathy. We will also discuss the use of sodium-glucose cotransporter 2 inhibitors as a therapy for diabetic cardiomyopathy and their known impacts on non-myocytes. These developments will no doubt facilitate the discovery of novel treatment targets for preventing the onset and progression of diabetic cardiomyopathy.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 07 Apr 2022; epub ahead of print

CRISPR and Cardiovascular Diseases.

Musunuru K
CRISPR technologies have progressed by leaps and bounds over the past decade, not only having a transformative effect on biomedical research but also yielding new therapies that are poised to enter the clinic. In this review, I give an overview of (1) the various CRISPR DNA-editing technologies, including standard nuclease gene editing, base editing, prime editing, and epigenome editing, (2) their impact on cardiovascular basic science research, including animal models, human pluripotent stem cell models, and functional screens, and (3) emerging therapeutic applications for patients with cardiovascular diseases, focusing on the examples of hypercholesterolemia, transthyretin amyloidosis, and Duchenne muscular dystrophy.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 07 Apr 2022; epub ahead of print

A mitochondrial long-chain fatty acid oxidation defect leads to tRNA uncharging and activation of the integrated stress response in the mouse heart.

Ranea-Robles P, Pavlova NN, Bender A, Pereyra AS, ... Puchowicz M, Houten SM
Aims
Cardiomyopathy and arrhythmias can be severe presentations in patients with inherited defects of mitochondrial long-chain fatty acid β-oxidation (FAO). The pathophysiological mechanisms that underlie these cardiac abnormalities remain largely unknown. We investigated the molecular adaptations to a FAO deficiency in the heart using the long-chain acyl-CoA dehydrogenase (LCAD) knockout (KO) mouse model.
Methods and results
We observed enrichment of amino acid metabolic pathways and of ATF4 target genes among the upregulated genes in the LCAD KO heart transcriptome. We also found a prominent activation of the eIF2α/ATF4 axis at the protein level that was independent of the feeding status, in addition to a reduction of cardiac protein synthesis during a short period of food withdrawal. These findings are consistent with an activation of the integrated stress response (ISR) in the LCAD KO mouse heart. Notably, charging of several tRNAs, such as tRNAGln was decreased in LCAD KO hearts, reflecting a reduced availability of cardiac amino acids, in particular, glutamine. We replicated the activation of the ISR in hearts of mice with a muscle-specific deletion of carnitine palmitoyltransferase 2.
Conclusions
Our results show that perturbations in amino acid metabolism caused by long-chain FAO deficiency impact on cardiac metabolic signaling, in particular the ISR. These results may serve as a foundation for investigating the role of the ISR in the cardiac pathology associated with long-chain FAO defects.Translational Perspective: The heart relies mainly on mitochondrial fatty acid β-oxidation (FAO) for its high energy requirements. The heart disease observed in patients with a genetic defect in this pathway highlights the importance of FAO for cardiac health. We show that the consequences of a FAO defect extend beyond cardiac energy homeostasis and include amino acid metabolism and associated signaling pathways such as the integrated stress response.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 07 Apr 2022; epub ahead of print

Frequent premature atrial contractions as a signalling marker of atrial cardiomyopathy, incident atrial fibrillation and stroke.

Farinha JM, Gupta D, Lip GYH
Premature atrial contractions are a common cardiac phenomenon. Although previously considered a benign electrocardiographic finding, they have now been associated with a higher risk of incident atrial fibrillation and other adverse outcomes such as stroke and all-cause mortality. Since premature atrial contractions can be associated with these adverse clinical outcomes independently of atrial fibrillation occurrence, different explanations have being proposed. The concept of atrial cardiomyopathy, where atrial fibrillation would be an epiphenomenon outside the causal pathway between premature atrial contractions and stroke has received traction recently. This concept suggests that structural, functional and biochemical changes in the atria lead to arrhythmia occurrence and thromboembolic events. Some consensus about diagnosis and treatment of this condition have been published, but this is based on scarce evidence, highlighting the need for a clear definition of excessive premature atrial contractions and for prospective studies regarding antiarrhythmic therapies, anticoagulation or molecular targets in this group of patients.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology.

Cardiovasc Res: 07 Apr 2022; epub ahead of print

Metaboloepigenetics in cancer, immunity and cardiovascular disease.

Keating ST, El-Osta A
The influence of cellular metabolism on epigenetic pathways are well documented but misunderstood. Scientists have long known of the metabolic impact on epigenetic determinants. More often than not, that title role for DNA methylation was portrayed by the metabolite SAM or S-adenosylmethionine. Technically speaking there are many other metabolites that drive epigenetic processes that instruct seemingly distant - yet highly connect pathways - and none more so than our understanding of the cancer epigenome. Recent studies have shown that available energy link the extracellular environment to influence cellular responses. This focused review examines the recent interest in epigenomics and casts cancer, metabolism and immunity in unfamiliar roles - cooperating. There are not only language lessons from cancer research, we have come round to appreciate that reaching into areas previously thought of as too distinct are also object lessons in understanding health and disease. The Warburg effect is one such signature of how glycolysis influences metabolic shift during oncogenesis. That shift in metabolism - now recognised as central to proliferation in cancer biology - influence core enzymes that not only control gene expression but are also central to replication, condensation and the repair of nucleic acid. These nuclear processes rely on metabolism and with glucose at center stage the role of respiration and oxidative metabolism are now synonymous with the mitochondria as the powerhouses of metaboloepigenetics. The emerging evidence for metaboloepigenetics in trained innate immunity has revealed recognisable signalling pathways with antecedent extracellular stimulation. With due consideration to immunometabolism we discuss the striking signalling similarities influencing these core pathways. The immunometabolic-epigenetic axis in cardiovascular disease has deeply etched connections with inflammation and we examine the chromatin template as a carrier of epigenetic indices that determine the expression of genes influencing atherosclerosis and vascular complications of diabetes.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 07 Apr 2022; epub ahead of print

RNF207 exacerbates pathological cardiac hypertrophy via post-translational modification of TAB1.

Yuan L, Bu S, Du M, Wang Y, ... Yang L, Huang K
Aims
The heart undergoes pathological remodeling, featured by the hypertrophic growth of cardiomyocytes and increased cardiac fibrosis, under biomechanical stress such as hemodynamic overload. RNF207 is an E3 ubiquitin ligase that is predominantly expressed in the heart, but its function remains elusive. In this study, we aimed to explore the role of RNF207 in the development of pathological cardiac hypertrophy and dysfunction.
Methods and results
Transverse aortic constriction (TAC) surgery was performed on mice to induce cardiac hypertrophy. Cardiac function and remodeling were evaluated by echocardiography, histological assessment and molecular analyses. Our data indicated that RNF207 overexpression (OE) exacerbated cardiac hypertrophy, fibrosis and systolic dysfunction. In contrast, TAC-induced cardiac remodeling was profoundly blunted in RNF207 knockdown (KD) hearts. In line with the in vivo findings, RNF207 OE augmented, while RNF207 KD alleviated, phenylephrine-induced cardiomyocyte hypertrophy in vitro. Mechanistically, we demonstrated that RNF207 elicited detrimental effects by promoting K63-linked ubiquitination of TAB1, which triggered the autophosphorylation of TAK1 and the activation of downstream p38 and JNK1/2 signaling pathways. In the TAB1 knockdown cardiomyocytes, RNF207 OE-induced cell hypertrophy was significantly attenuated, indicating that RNF207-induced hypertrophy is, at least in part, TAB1 dependent.
Conclusions
This study demonstrates that RNF207 exacerbates pressure overload-induced cardiac hypertrophy and dysfunction via post-translational modification of TAB1.
Translational perspective
There is currently a lack of treatment to effectively prevent or reverse cardiac hypertrophy and heart failure, which has brought the importance of in-depth understanding of the molecular mechanisms that drives the pathological cardiac growth and the discovery of novel therapeutic targets. Our work demonstrates for the first time that RNF207 exaggerates pressure overload-induced cardiac hypertrophy and dysfunction. This is due, at least in part, to the polyubiquitination of TAB1, which triggers the autophosphorylation of TAK1 and activation of TAK1-p38 and TAK1-JNK1/2 signaling pathways. These data suggest that RNF207 may be a potential therapeutic target in the treatment of cardiac hypertrophy and failure.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 30 Mar 2022; 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, ... Petegem FV, 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 of proteins. As the most commonly occurring post-translational modification, 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.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.

Cardiovasc Res: 25 Mar 2022; 118:1205-1217

Dietary recommendations for prevention of atherosclerosis.

Riccardi G, Giosuè A, Calabrese I, Vaccaro O
This review aims at summarizing updated evidence on cardiovascular disease (CVD) risk associated with consumption of specific food items to substantiate dietary strategies for atherosclerosis prevention. A systematic search on PubMed was performed to identify meta-analyses of cohort studies and RCTs with CVD outcomes. The evidence is highly concordant in showing that, for the healthy adult population, low consumption of salt and foods of animal origin, and increased intake of plant-based foods-whole grains, fruits, vegetables, legumes, and nuts-are linked with reduced atherosclerosis risk. The same applies for the replacement of butter and other animal/tropical fats with olive oil and other unsaturated-fat-rich oil. Although the literature reviewed overall endorses scientific society dietary recommendations, some relevant novelties emerge. With regard to meat, new evidence differentiates processed and red meat-both associated with increased CVD risk-from poultry, showing a neutral relationship with CVD for moderate intakes. Moreover, the preferential use of low-fat dairies in the healthy population is not supported by recent data, since both full-fat and low-fat dairies, in moderate amounts and in the context of a balanced diet, are not associated with increased CVD risk; furthermore, small quantities of cheese and regular yogurt consumption are even linked with a protective effect. Among other animal protein sources, moderate fish consumption is also supported by the latest evidence, although there might be sustainability concerns. New data endorse the replacement of most high glycemic index (GI) foods with both whole grain and low GI cereal foods. As for beverages, low consumption not only of alcohol, but also of coffee and tea is associated with a reduced atherosclerosis risk while soft drinks show a direct relationship with CVD risk. This review provides evidence-based support for promoting appropriate food choices for atherosclerosis prevention in the general population.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.

Cardiovasc Res: 25 Mar 2022; 118:1188-1204

Arginase II protein regulates Parkin-dependent p32 degradation that contributes to Ca2+-dependent eNOS activation in endothelial cells.

Koo BH, Won MH, Kim YM, Ryoo S
Aims
Arginase II (ArgII) plays a key role in the regulation of Ca2+ between the cytosol and mitochondria in a p32-dependent manner. p32 contributes to endothelial nitric oxide synthase (eNOS) activation through the Ca2+/CaMKII/AMPK/p38MAPK/Akt signalling cascade. Therefore, we investigated a novel function of ArgII in the regulation of p32 stability.
Methods and results
mRNA levels were measured by quantitative reverse transcription-PCR, and protein levels and activation were confirmed by western blot analysis. Ca2+ concentrations were measured by FACS analysis and a vascular tension assay was performed. ArgII bound to p32, and ArgII protein knockdown using siArgII facilitated the ubiquitin-dependent proteasomal degradation of p32. β-lactone, a proteasome inhibitor, inhibited the p32 degradation associated with endothelial dysfunction in a Ca2+-dependent manner. The amino acids Lys154, Lys 180, and Lys220 of the p32 protein were identified as putative ubiquitination sites. When these sites were mutated, p32 was resistant to degradation in the presence of siArgII, and endothelial function was impaired. Knockdown of Pink/Parkin as an E3-ubiquitin ligase with siRNAs resulted in increased p32, decreased [Ca2+]c, and attenuated CaMKII-dependent eNOS activation by siArgII. siArgII-dependent Parkin activation was attenuated by KN93, a CaMKII inhibitor. Knockdown of ArgII mRNA and its gene, but not inhibition of its activity, accelerated the interaction between p32 and Parkin and reduced p32 levels. In aortas of ArgII-/- mice, p32 levels were reduced by activated Parkin and inhibition of CaMKII attenuated Parkin-dependent p32 lysis. siParkin blunted the phosphorylation of the activated CaMKII/AMPK/p38MAPK/Akt/eNOS signalling cascade. However, ApoE-/- mice fed a high-cholesterol diet had greater ArgII activity, significantly attenuated phosphorylation of Parkin, and increased p32 levels. Incubation with siArgII augmented p32 ubiquitination through Parkin activation, and induced signalling cascade activation.
Conclusion
The results suggest a novel function for ArgII protein in Parkin-dependent ubiquitination of p32 that is associated with Ca2+-mediated eNOS activation in endothelial cells.

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

Cardiovasc Res: 25 Mar 2022; 118:1344-1358

Senescence mechanisms and targets in the heart.

Chen MS, Lee RT, Garbern JC
Cellular senescence is a state of irreversible cell cycle arrest associated with ageing. Senescence of different cardiac cell types can direct the pathophysiology of cardiovascular diseases (CVDs) such as atherosclerosis, myocardial infarction, and cardiac fibrosis. While age-related telomere shortening represents a major cause of replicative senescence, the senescent state can also be induced by oxidative stress, metabolic dysfunction, and epigenetic regulation, among other stressors. It is critical that we understand the molecular pathways that lead to cellular senescence and the consequences of cellular senescence in order to develop new therapeutic approaches to treat CVD. In this review, we discuss molecular mechanisms of cellular senescence, explore how cellular senescence of different cardiac cell types (including cardiomyocytes, cardiac endothelial cells, cardiac fibroblasts, vascular smooth muscle cells, and valve interstitial cells) can lead to CVD, and highlight potential therapeutic approaches that target molecular mechanisms of cellular senescence to prevent or treat CVD.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.

Cardiovasc Res: 25 Mar 2022; 118:1173-1187

Endothelial Zeb2 preserves the hepatic angioarchitecture and protects against liver fibrosis.

de Haan W, Dheedene W, Apelt K, Décombas-Deschamps S, ... Huylebroeck D, Luttun A
Aims
Hepatic capillaries are lined with specialized liver sinusoidal endothelial cells (LSECs) which support macromolecule passage to hepatocytes and prevent fibrosis by keeping hepatic stellate cells (HSCs) quiescent. LSEC specialization is co-determined by transcription factors. The zinc-finger E-box-binding homeobox (Zeb)2 transcription factor is enriched in LSECs. Here, we aimed to elucidate the endothelium-specific role of Zeb2 during maintenance of the liver and in liver fibrosis.
Methods and results
To study the role of Zeb2 in liver endothelium we generated EC-specific Zeb2 knock-out (ECKO) mice. Sequencing of liver EC RNA revealed that deficiency of Zeb2 results in prominent expression changes in angiogenesis-related genes. Accordingly, the vascular area was expanded and the presence of pillars inside ECKO liver vessels indicated that this was likely due to increased intussusceptive angiogenesis. LSEC marker expression was not profoundly affected and fenestrations were preserved upon Zeb2 deficiency. However, an increase in continuous EC markers suggested that Zeb2-deficient LSECs are more prone to dedifferentiation, a process called \'capillarization\'. Changes in the endothelial expression of ligands that may be involved in HSC quiescence together with significant changes in the expression profile of HSCs showed that Zeb2 regulates LSEC-HSC communication and HSC activation. Accordingly, upon exposure to the hepatotoxin carbon tetrachloride (CCl4), livers of ECKO mice showed increased capillarization, HSC activation, and fibrosis compared to livers from wild-type littermates. The vascular maintenance and anti-fibrotic role of endothelial Zeb2 was confirmed in mice with EC-specific overexpression of Zeb2, as the latter resulted in reduced vascularity and attenuated CCl4-induced liver fibrosis.
Conclusion
Endothelial Zeb2 preserves liver angioarchitecture and protects against liver fibrosis. Zeb2 and Zeb2-dependent genes in liver ECs may be exploited to design novel therapeutic strategies to attenuate hepatic fibrosis.

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

Cardiovasc Res: 25 Mar 2022; 118:1262-1275

Deficiency of myeloid PHD proteins aggravates atherogenesis via macrophage apoptosis and paracrine fibrotic signalling.

van Kuijk K, Demandt JAF, Perales-Patón J, Theelen TL, ... Saez-Rodriguez J, Sluimer JC
Aims
Atherosclerotic plaque hypoxia is detrimental for macrophage function. Prolyl hydroxylases (PHDs) initiate cellular hypoxic responses, possibly influencing macrophage function in plaque hypoxia. Thus, we aimed to elucidate the role of myeloid PHDs in atherosclerosis.
Methods and results
Myeloid-specific PHD knockout (PHDko) mice were obtained via bone marrow transplantation (PHD1ko, PHD3ko) or conditional knockdown through lysozyme M-driven Cre recombinase (PHD2cko). Mice were fed high cholesterol diet for 6-12 weeks to induce atherosclerosis. Aortic root plaque size was significantly augmented 2.6-fold in PHD2cko, and 1.4-fold in PHD3ko compared to controls but was unchanged in PHD1ko mice. Macrophage apoptosis was promoted in PHD2cko and PHD3ko mice in vitro and in vivo, via the hypoxia-inducible factor (HIF) 1α/BNIP3 axis. Bulk and single-cell RNA data of PHD2cko bone marrow-derived macrophages (BMDMs) and plaque macrophages, respectively, showed enhanced HIF1α/BNIP3 signalling, which was validated in vitro by siRNA silencing. Human plaque BNIP3 mRNA was positively associated with plaque necrotic core size, suggesting similar pro-apoptotic effects in human. Furthermore, PHD2cko plaques displayed enhanced fibrosis, while macrophage collagen breakdown by matrix metalloproteinases, collagen production, and proliferation were unaltered. Instead, PHD2cko BMDMs enhanced fibroblast collagen secretion in a paracrine manner. In silico analysis of macrophage-fibroblast communication predicted SPP1 (osteopontin) signalling as regulator, which was corroborated by enhanced plaque SPP1 protein in vivo. Increased SPP1 mRNA expression upon PHD2cko was preferentially observed in foamy plaque macrophages expressing \'triggering receptor expressed on myeloid cells-2\' (TREM2hi) evidenced by single-cell RNA, but not in neutrophils. This confirmed enhanced fibrotic signalling by PHD2cko macrophages to fibroblasts, in vitro as well as in vivo.
Conclusion
Myeloid PHD2cko and PHD3ko enhanced atherosclerotic plaque growth and macrophage apoptosis, while PHD2cko macrophages further activated collagen secretion by fibroblasts in vitro, likely via paracrine SPP1 signalling through TREM2hi macrophages.

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

Cardiovasc Res: 25 Mar 2022; 118:1232-1246

Epidermal growth factor receptor-dependent maintenance of cardiac contractility.

Guo S, Okyere AD, McEachern E, Strong JL, ... Cheung JY, Tilley DG
Aims
Epidermal growth factor receptor (EGFR) is essential to the development of multiple tissues and organs and is a target of cancer therapeutics. Due to the embryonic lethality of global EGFR deletion and conflicting reports of cardiac-overexpressed EGFR mutants, its specific impact on the adult heart, normally or in response to chronic stress, has not been established. Using complimentary genetic strategies to modulate cardiomyocyte-specific EGFR expression, we aim to define its role in the regulation of cardiac function and remodelling.
Methods and results
A floxed EGFR mouse model with α-myosin heavy chain-Cre-mediated cardiomyocyte-specific EGFR downregulation (CM-EGFR-KD mice) developed contractile dysfunction by 9 weeks of age, marked by impaired diastolic relaxation, as monitored via echocardiographic, haemodynamic, and isolated cardiomyocyte contractility analyses. This contractile defect was maintained over time without overt cardiac remodelling until 10 months of age, after which the mice ultimately developed severe heart failure and reduced lifespan. Acute downregulation of EGFR in adult floxed EGFR mice with adeno-associated virus 9 (AAV9)-encoded Cre with a cardiac troponin T promoter (AAV9-cTnT-Cre) recapitulated the CM-EGFR-KD phenotype, while AAV9-cTnT-EGFR treatment of adult CM-EGFR-KD mice rescued the phenotype. Notably, chronic administration of the β-adrenergic receptor agonist isoproterenol effectively and reversibly compensated for the contractile dysfunction in the absence of cardiomyocyte hypertrophy in CM-EGFR-KD mice. Mechanistically, EGFR downregulation reduced the expression of protein phosphatase 2A regulatory subunit Ppp2r3a/PR72, which was associated with decreased phosphorylation of phospholamban and Ca2+ clearance, and whose re-expression via AAV9-cTnT-PR72 rescued the CM-EGFR-KD phenotype.
Conclusions
Altogether, our study highlights a previously unrecognized role for EGFR in maintaining contractile homeostasis under physiologic conditions in the adult heart via regulation of PR72 expression.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.

Cardiovasc Res: 25 Mar 2022; 118:1276-1288

Assessment of arrhythmia mechanism and burden of the infarcted ventricles following remuscularization with pluripotent stem cell-derived cardiomyocyte patches using patient-derived models.

Yu JK, Liang JA, Franceschi WH, Huang Q, ... Boyle PM, Trayanova NA
Aims
Direct remuscularization with pluripotent stem cell-derived cardiomyocytes (PSC-CMs) seeks to address the onset of heart failure post-myocardial infarction (MI) by treating the persistent muscle deficiency that underlies it. However, direct remuscularization with PSC-CMs could potentially be arrhythmogenic. We investigated two possible mechanisms of arrhythmogenesis-focal vs. re-entrant-arising from direct remuscularization with PSC-CM patches in two personalized, human ventricular computer models of post-MI. Moreover, we developed a principled approach for evaluating arrhythmogenicity of direct remuscularization that factors in the VT propensity of the patient-specific post-MI fibrotic substrate and use it to investigate different conditions of patch remuscularization.
Methods and results
Two personalized, human ventricular models of post-MI (P1 and P2) were constructed from late gadolinium enhanced (LGE)-magnetic resonance images (MRIs). In each model, remuscularization with PSC-CM patches was simulated under different treatment conditions that included patch engraftment, patch myofibril orientation, remuscularization site, patch size (thickness and diameter), and patch maturation. To determine arrhythmogenicity of treatment conditions, VT burden of heart models was quantified prior to and after simulated remuscularization and compared. VT burden was quantified based on inducibility (i.e. weighted sum of pacing sites that induced) and severity (i.e. the number of distinct VT morphologies induced). Prior to remuscularization, VT burden was significant in P1 (0.275) and not in P2 (0.0, not VT inducible). We highlight that re-entrant VT mechanisms would dominate over focal mechanisms; spontaneous beats emerging from PSC-CM grafts were always a fraction of resting sinus rate. Moreover, incomplete patch engraftment can be particularly arrhythmogenic, giving rise to particularly aberrant electrical activation and conduction slowing across the PSC-CM patches along with elevated VT burden when compared with complete engraftment. Under conditions of complete patch engraftment, remuscularization was almost always arrhythmogenic in P2 but certain treatment conditions could be anti-arrhythmogenic in P1. Moreover, the remuscularization site was the most important factor affecting VT burden in both P1 and P2. Complete maturation of PSC-CM patches, both ionically and electrotonically, at the appropriate site could completely alleviate VT burden.
Conclusion
We identified that re-entrant VT would be the primary VT mechanism in patch remuscularization. To evaluate the arrhythmogenicity of remuscularization, we developed a principled approach that factors in the propensity of the patient-specific fibrotic substrate for VT. We showed that arrhythmogenicity is sensitive to the patient-specific fibrotic substrate and remuscularization site. We demonstrate that targeted remuscularization can be safe in the appropriate individual and holds the potential to non-destructively eliminate VT post-MI in addition to addressing muscle deficiency underlying heart failure progression.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.

Cardiovasc Res: 25 Mar 2022; 118:1247-1261

The voltage-gated potassium channel KV1.3 regulates neutrophil recruitment during inflammation.

Immler R, Nadolni W, Bertsch A, Morikis V, ... Pruenster M, Sperandio M
Aims
Neutrophil trafficking within the vasculature strongly relies on intracellular calcium signalling. Sustained Ca2+ influx into the cell requires a compensatory efflux of potassium to maintain membrane potential. Here, we aimed to investigate whether the voltage-gated potassium channel KV1.3 regulates neutrophil function during the acute inflammatory process by affecting sustained Ca2+ signalling.
Methods and results
Using in vitro assays and electrophysiological techniques, we show that KV1.3 is functionally expressed in human neutrophils regulating sustained store-operated Ca2+ entry through membrane potential stabilizing K+ efflux. Inhibition of KV1.3 on neutrophils by the specific inhibitor 5-(4-Phenoxybutoxy)psoralen (PAP-1) impaired intracellular Ca2+ signalling, thereby preventing cellular spreading, adhesion strengthening, and appropriate crawling under flow conditions in vitro. Using intravital microscopy, we show that pharmacological blockade or genetic deletion of KV1.3 in mice decreased neutrophil adhesion in a blood flow dependent fashion in inflamed cremaster muscle venules. Furthermore, we identified KV1.3 as a critical component for neutrophil extravasation into the inflamed peritoneal cavity. Finally, we also revealed impaired phagocytosis of Escherichia coli particles by neutrophils in the absence of KV1.3.
Conclusion
We show that the voltage-gated potassium channel KV1.3 is critical for Ca2+ signalling and neutrophil trafficking during acute inflammatory processes. Our findings do not only provide evidence for a role of KV1.3 for sustained calcium signalling in neutrophils affecting key functions of these cells, they also open up new therapeutic approaches to treat inflammatory disorders characterized by overwhelming neutrophil infiltration.

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

Cardiovasc Res: 25 Mar 2022; 118:1289-1302

Single-cell transcriptomic analyses of cardiac immune cells reveal that Rel-driven CD72-positive macrophages induce cardiomyocyte injury.

Ni SH, Xu JD, Sun SN, Li Y, ... Wang LJ, Lu L
Aims 
The goal of our study was to investigate the heterogeneity of cardiac macrophages (CMφs) in mice with transverse aortic constriction (TAC) via single-cell sequencing and identify a subset of macrophages associated with heart injury.
Methods and results 
We selected all CMφs from CD45+ cells using single-cell mRNA sequencing data. Through dimension reduction, clustering, and enrichment analyses, CD72hi CMφs were identified as a subset of pro-inflammatory macrophages. The pseudo-time trajectory and ChIP-Seq analyses identified Rel as the key transcription factor that induces CD72hi CMφ differentiation. Rel KD and Rel-/- bone marrow chimaera mice subjected to TAC showed features of mitigated cardiac injury, including decreased levels of cytokines and ROS, which prohibited cardiomyocyte death. The transfer of adoptive Rel-overexpressing monocytes and CD72hi CMφ injection directly aggravated heart injury in the TAC model. The CD72hi macrophages also exerted pro-inflammatory and cardiac injury effects associated with myocardial infarction. In humans, patients with heart failure exhibit increased CD72hi CMφ levels following dilated cardiomyopathy and ischaemic cardiomyopathy.
Conclusion 
Bone marrow-derived, Rel-mediated CD72hi macrophages play a pro-inflammatory role, induce cardiac injury and, thus, may serve as a therapeutic target for multiple cardiovascular diseases.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.

Cardiovasc Res: 25 Mar 2022; 118:1303-1320

Neuronal nitric oxide synthase regulates regional brain perfusion in healthy humans.

O\'Gallagher K, Puledda F, O\'Daly O, Ryan M, ... Goadsby PJ, Shah AM
Aims
Neuronal nitric oxide synthase (nNOS) is highly expressed within the cardiovascular and nervous systems. Studies in genetically modified mice suggest roles in brain blood flow regulation while dysfunctional nNOS signalling is implicated in cerebrovascular ischaemia and migraine. Previous human studies have investigated the effects of non-selective NOS inhibition but there has been no direct investigation of the role of nNOS in human cerebrovascular regulation. We hypothesized that inhibition of the tonic effects of nNOS would result in global or localized changes in cerebral blood flow (CBF), as well as changes in functional brain connectivity.
Methods and results
We investigated the acute effects of a selective nNOS inhibitor, S-methyl-L-thiocitrulline (SMTC), on CBF and brain functional connectivity in healthy human volunteers (n = 19). We performed a randomized, placebo-controlled, crossover study with either intravenous SMTC or placebo, using magnetic resonance imaging protocols with arterial spin labelling and functional resting state neuroimaging. SMTC infusion induced an ∼4% decrease in resting global CBF [-2.3 (-0.3, -4.2) mL/100g/min, mean (95% confidence interval, CI), P = 0.02]. In a whole-brain voxel-wise factorial-design comparison of CBF maps, we identified a localized decrease in regional blood flow in the right hippocampus and parahippocampal gyrus following SMTC vs. placebo (2921 voxels; T = 7.0; x = 36; y = -32; z = -12; P < 0.001). This was accompanied by a decrease in functional connectivity to the left superior parietal lobule vs. placebo (484 voxels; T = 5.02; x = -14; y = -56; z = 74; P = 0.009). These analyses adjusted for the modest changes in mean arterial blood pressure induced by SMTC as compared to placebo [+8.7 mmHg (+1.8, +15.6), mean (95% CI), P = 0.009].
Conclusions
These data suggest a fundamental physiological role of nNOS in regulating regional CBF and functional connectivity in the human hippocampus. Our findings have relevance to the role of nNOS in the regulation of cerebral perfusion in health and disease.

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

Cardiovasc Res: 25 Mar 2022; 118:1321-1329

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

Swerdlow DI, Rider DA, Yavari A, Wikström Lindholm M, 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 Lp(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 Lp(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-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 Lp(a) lowering with as few as three or four doses per year. In this review, we evaluate the causal role of Lp(a) across the cardiovascular disease spectrum, examine the role of established lipid-modifying therapies in lowering Lp(a), and focus on the anticipated role for siRNA therapeutics in treating and preventing Lp(a)-related disease.

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

Cardiovasc Res: 25 Mar 2022; 118:1218-1231

Single-cell transcriptomes in the heart: when every epigenome counts.

Gromova T, Gehred ND, Vondriska TM
The response of an organ to stimuli emerges from the actions of individual cells. Recent cardiac single cell RNA-sequencing studies of development, injury and reprogramming have uncovered heterogeneous populations even among previously well-defined cell types, raising questions about what level of experimental resolution corresponds to disease-relevant, tissue-level phenotypes. In this review, we explore the biological meaning behind this cellular heterogeneity by undertaking an exhaustive analysis of single cell transcriptomics in the heart (including a comprehensive, annotated compendium of studies published to date) and evaluating new models for cardiac function that have emerged from these studies (including discussion and schematics that depict new hypotheses in the field). We evaluate the evidence to support the biological actions of newly identified cell populations and debate questions related to the role of cell-to-cell variability in development and disease. Lastly, we present emerging epigenomic approaches that, when combined with single cell RNA-sequencing, can resolve basic mechanisms of gene regulation and variability in cell phenotype.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 24 Mar 2022; epub ahead of print

Methods for the identification and characterization of extracellular vesicles in cardiovascular studies - from exosomes to microvesicles.

Davidson SM, Boulanger CM, Aikawa E, Badimon L, ... Witwer K, Sluijter JPG
Extracellular vesicles (EVs) are nanosized vesicles with a lipid bilayer that are released from cells of the cardiovascular system, and are considered important mediators of intercellular and extracellular communication. Two types of EV of particular interest are exosomes and microvesicles, which have been identified in all tissue and body fluids and carry a variety of molecules including RNAs, proteins, and lipids. EVs have potential for use in the diagnosis and prognosis of cardiovascular diseases and as new therapeutic agents, particularly in the setting of myocardial infarction and heart failure. Despite their promise, technical challenges related to their small size make it challenging to accurately identify and characterize them, and to study EV-mediated processes. Here, we aim to provide the reader with an overview of the techniques and technologies available for the separation and characterization of EVs from different sources. Methods for determining the protein, RNA and lipid content of EVs are discussed. The aim of this document is to provide guidance on critical methodological issues and highlight key points for consideration for the investigation of EVs in cardiovascular studies.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 24 Mar 2022; epub ahead of print

The regulation of cardiac intermediary metabolism by NADPH oxidases.

Nabeebaccus AA, Reumiller CM, Shen J, Zoccarato A, Santos CX, Shah AM
NADPH oxidase enzymes (NOXs), enzymes whose primary function is to generate reactive oxygen species, are important regulators of the heart\'s physiological function and response to pathological insults. The role of NOX-driven redox signalling in pathophysiological myocardial remodelling, including processes such as interstitial fibrosis, contractile dysfunction, cellular hypertrophy and cell survival, is well recognised. While the NOX2 isoform promotes many detrimental effects, the NOX4 isoform has attracted considerable attention as a driver of adaptive stress responses both during pathology and under physiological states such as exercise. Recent studies have begun to define some of the NOX4-modulated mechanisms that may underlie these adaptive responses. In particular, novel functions of NOX4 in driving cellular metabolic changes have emerged. Alterations in cellular metabolism are a recognised hallmark of the heart\'s response to physiological and pathological stresses. In this review, we highlight the emerging roles of NOX enzymes as important modulators of cellular intermediary metabolism in the heart, linking stress responses not only to myocardial energetics but also other functions. The novel interplay of NOX-modulated redox signalling pathways and intermediary metabolism in the heart is unravelling a new aspect of the fascinating biology of these enzymes which will inform better understanding of how they drive adaptative responses. We also discuss the implications of these new findings for therapeutic approaches that target metabolism in cardiac disease.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology.

Cardiovasc Res: 24 Mar 2022; epub ahead of print

Endothelial OCT4 is atheroprotective by preventing metabolic and phenotypic dysfunction.

Shin J, Tkachenko S, Chaklader M, Pletz C, ... Owens GK, Cherepanova OA
Aims
Until recently, the pluripotency factor OCT4 was believed to be dispensable in adult somatic cells. However, our recent studies provided clear evidence that OCT4 has a critical atheroprotective role in smooth muscle cells (SMC). Here, we asked if OCT4 might play a functional role in regulating endothelial cell (EC) phenotypic modulations in atherosclerosis.
Methods and results
Specifically, we show that EC-specific Oct4 knockout resulted in increased lipid, LGALS3+ cell accumulation, and altered plaque characteristics consistent with decreased plaque stability. A combination of single-cell RNA sequencing and EC-lineage-tracing studies revealed increased EC activation, endothelial-to-mesenchymal transitions, plaque neovascularization, and mitochondrial dysfunction in the absence of OCT4. Further, we show that the ATP transporter, ABCG2, is a direct target of OCT4 in EC and establish for the first time that the OCT4/ABCG2 axis maintains EC metabolic homeostasis by regulating intracellular heme accumulation and related reactive oxygen species production, which, in turn, contributes to atherogenesis.
Conclusions
These results provide the first direct evidence that OCT4 has a protective metabolic function in EC and identifies vascular OCT4 and its signaling axis as a potential target for novel therapeutics.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cardiovasc Res: 24 Mar 2022; epub ahead of print

MRI Contrast-enhancement with superparamagnetic iron oxide nanoparticles amplify macrophage foam cell apoptosis in human and murine atherosclerosis.

Segers FME, Ruder AV, Westra MM, Lammers T, ... Sluimer JC, Biessen EAL
Aims
(Ultra) Small superparamagnetic iron oxide nanoparticles, (U)SPIO, are widely used as magnetic resonance imaging contrast media and assumed to be safe for clinical applications in cardiovascular disease. As safety tests largely relied on normolipidemic models, not fully representative of the clinical setting, we investigated the impact of (U)SPIOs on disease-relevant endpoints in hyperlipidemic models of atherosclerosis.
Methods and results
RAW264.7 foam cells, exposed in vitro to Ferumoxide (dextran-coated SPIO), Ferumoxtran (dextran-coated USPIO), or Ferumoxytol (carboxymethyl dextran-coated USPIO) (all 1 mg Fe/ml) showed increased apoptosis and ROS accumulation for Ferumoxide and Ferumoxtran, whereas Ferumoxytol was tolerated well. Pro-apoptotic (TUNEL+) and pro-oxidant activity of Ferumoxide (0.3 mg Fe/kg) and Ferumoxtran (1 mg Fe/kg) were confirmed in plaque, spleen, and liver of hyperlipidemic ApoE-/- (n = 9/group) and LDLR-/- (n = 9-16/group) mice that had received single IV injections compared to saline-treated controls. Again, Ferumoxytol treatment (1 mg Fe/kg) failed to induce apoptosis or oxidative stress in these tissues. Concomitant antioxidant treatment (EUK-8/EUK-134) largely prevented these effects in vitro (-68%, P < 0.05) and in plaques from LDLR-/- mice (-60%, P  < 0.001, n = 8/group). Repeated Ferumoxtran injections of LDLR-/- mice with pre-existing atherosclerosis enhanced plaque inflammation and apoptosis but did not alter plaque size. Strikingly, carotid artery plaques of endarterectomy patients who received Ferumoxtran (2.6 mg Fe/kg) before surgery (n = 9) also showed 5-fold increased apoptosis (18.2 vs. 3.7% respectively; P = 0.004) compared to controls who did not receive Ferumoxtran. Mechanistically, neither coating nor particle size seemed accountable for the observed cytotoxicity of Ferumoxide and Ferumoxtran.
Conclusions
Ferumoxide and Ferumoxtran, but not Ferumoxytol, induced apoptosis of lipid-laden macrophages in human and murine atherosclerosis, potentially impacting disease progression in patients with advanced atherosclerosis.

© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology.

Cardiovasc Res: 23 Mar 2022; 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 (LPK) 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 LPK rats while <1% of neurons were Fos/Fra+ in Lewis control rats (P = 0.01, n = 8). In anaesthetized rats, subfornical organ neuronal inhibition using isoguvacine produced a greater reduction in systolic blood pressure in LPK vs. 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 LPK 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 LPK 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.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.

Cardiovasc Res: 16 Mar 2022; 118:1138-1149

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

Jeong K, Murphy JM, Ahn EE, Lim SS
Aims
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 theCDKIs for degradation. FAK N-terminal domain interacts with Skp2 and an APC/C E3 ligase activator fizzy-related 1 (Fzr1) in the nucleus, which promote 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 signalling axis is distinct from the FAK-cyclin D1 pathway. However, overexpression of both cyclin D1 and Skp2 enabled proliferation of FAK-KD VSMCs, implicating that FAK ought to control both activating and inhibitory switches for CDKs. In vivo, wire injury activated FAK in the cytosol, which increased Skp2 and decreased p27 and p21 levels.
Conclusion
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 signalling negatively regulates CDK activity in VSMC proliferation.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.

Cardiovasc Res: 16 Mar 2022; 118:1150-1163

Effects of canagliflozin on myocardial infarction: a post hoc analysis of the CANVAS programme 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 Programme and CREDENCE trial.
Methods and results
Individuals with type 2 diabetes and history or high risk of cardiovascular disease (CANVAS Programme) 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, and type 1 MI or type 2 MI. A total of 421 first MI events in the CANVAS Programme 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 [hazard ratio (HR) 0.89; 95% confidence interval (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).
Conclusion
Canagliflozin was not associated with a reduction in overall MI in the pooled CANVAS Programme and CREDENCE trial population. The possible differential effect on STEMI and Non-STEMI observed in the CANVAS cohort warrants further investigation.
Trial registration
ClinicalTrials.gov identifiers: NCT01032629, NCT01989754, and NCT02065791.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.

Cardiovasc Res: 16 Mar 2022; 118:1103-1114

Extracellular histones are a target in myocardial ischaemia-reperfusion injury.

Shah M, He Z, Rauf A, Beikoghli Kalkhoran S, ... Davidson SM, Yellon D
Aims 
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. 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-neutralizing 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.

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

Cardiovasc Res: 16 Mar 2022; 118:1115-1125

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 10 CAD case-control studies and UK Biobank with focus on 8068 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.

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

Cardiovasc Res: 16 Mar 2022; 118:1088-1102

Arrhythmogenesis in the aged heart following ischaemia-reperfusion: role of transient receptor potential vanilloid 4.

Peana D, Polo-Parada L, Domeier TL
Aims
Cardiomyocyte Ca2+ homoeostasis is altered with ageing and predisposes the heart to Ca2+ intolerance and arrhythmia. Transient receptor potential vanilloid 4 (TRPV4) is an osmotically activated cation channel with expression in cardiomyocytes of the aged heart. The objective of this study was to examine the role of TRPV4 in Ca2+ handling and arrhythmogenesis following ischaemia-reperfusion (I/R), a pathological scenario associated with osmotic stress.
Methods and results
Cardiomyocyte membrane potential was monitored prior to and following I/R in Langendorff-perfused hearts of Aged (19-28 months) male and female C57BL/6 mice ± TRPV4 inhibition (1 μM HC067047, HC). Diastolic resting membrane potential was similar between Aged and Aged HC at baseline, but following I/R Aged exhibited depolarized diastolic membrane potential vs. Aged HC. The effects of TRPV4 on cardiomyocyte Ca2+ signalling following I/R were examined in isolated hearts of Aged cardiac-specific GCaMP6f mice (±HC) using high-speed confocal fluorescence microscopy, with cardiomyocytes of Aged exhibiting an increased incidence of pro-arrhythmic Ca2+ signalling vs. Aged HC. In the isolated cell environment, cardiomyocytes of Aged responded to sustained hypoosmotic stress (250mOsm) with an increase in Ca2+ transient amplitude (fluo-4) and higher incidence of pro-arrhythmic diastolic Ca2+ signals vs. Aged HC. Intracardiac electrocardiogram measurements in isolated hearts following I/R revealed an increased arrhythmia incidence, an accelerated time to ventricular arrhythmia, and increased arrhythmia score in Aged vs. Aged HC. Aged exhibited depolarized resting membrane potential, increased pro-arrhythmic diastolic Ca2+ signalling, and greater incidence of arrhythmia when compared with Young (3-5 months).
Conclusion
TRPV4 contributes to pro-arrhythmic cardiomyocyte Ca2+ signalling, electrophysiological abnormalities, and ventricular arrhythmia in the aged mouse heart.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.

Cardiovasc Res: 16 Mar 2022; 118:1126-1137

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, remodelling was worsened in Ffar4KO hearts, with greater hypertrophy and contractile dysfunction. Transcriptome analysis 3-day post-TAC identified transcriptional deficits in genes associated with cytoplasmic phospholipase A2α signalling and oxylipin synthesis and the reduction of oxidative stress in Ffar4KO myocytes. In cultured adult cardiac myocytes, Ffar4 induced the production of the eicosapentaenoic acid (EPA)-derived, pro-resolving oxylipin 18-hydroxyeicosapentaenoic acid (18-HEPE). Furthermore, the 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 signalling-deficient Ffar4 R270H polymorphism correlated with eccentric remodelling in a large clinical cohort paralleling changes observed in Ffar4KO mice post-TAC.
Conclusion
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: journals.permissions@oup.com.

Cardiovasc Res: 16 Mar 2022; 118:1061-1073

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 (i) marked DD not associated to cardiac fibrosis, (ii) LV mass reduction associated to reduced LV cell dimension and T-tubules loss, (iii) reduced LV SERCA2 protein level and activity and (iv) slower SR Ca2+ uptake rate, (v) LV action potential (AP) prolongation and increased short-term variability (STV) of AP duration, (vi) increased diastolic Ca2+, and (vii) 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.

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

Cardiovasc Res: 16 Mar 2022; 118:1020-1032

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 organized 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 standardized 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: 16 Mar 2022; 118:1004-1019

Tbx5 variants disrupt Nav1.5 function differently in patients diagnosed with Brugada or Long QT Syndrome.

Nieto-Marín P, Tinaquero D, Utrilla RG, Cebrián J, ... Delpón E, ITACA Consortium Investigators
Aims
The transcription factor Tbx5 controls cardiogenesis and drives Scn5a expression in mice. We have identified two variants in TBX5 encoding p. D111Y and p. F206L Tbx5, respectively, in two unrelated patients with structurally normal hearts diagnosed with long QT (LQTS) and Brugada (BrS) syndrome. Here, we characterized the consequences of each variant to unravel the underlying disease mechanisms.
Methods and results
We combined clinical analysis with in vivo and in vitro electrophysiological and molecular techniques in human-induced pluripotent stem-cell-derived cardiomyocytes (hiPSC-CMs), HL-1 cells, and cardiomyocytes from mice trans-expressing human wild-type (WT) or mutant proteins. Tbx5 increased transcription of SCN5A encoding cardiac Nav1.5 channels, while repressing CAMK2D and SPTBN4 genes encoding Ca/calmodulin kinase IIδ (CaMKIIδ) and βIV-spectrin, respectively. These effects significantly increased Na current (INa) in hiPSC-CMs and in cardiomyocytes from mice trans-expressing Tbx5. Consequently, action potential (AP) amplitudes increased and QRS interval narrowed in the mouse electrocardiogram. p. F206L Tbx5 bound to the SCN5A promoter failed to transactivate it, thus precluding the pro-transcriptional effect of WT Tbx5. Therefore, p. F206L markedly decreased INa in hiPSC-CM, HL-1 cells and mouse cardiomyocytes. The INa decrease in p. F206L trans-expressing mice translated into QRS widening and increased flecainide sensitivity. p. D111Y Tbx5 increased SCN5A expression but failed to repress CAMK2D and SPTBN4. The increased CaMKIIδ and βIV-spectrin significantly augmented the late component of INa (INaL) which, in turn, significantly prolonged AP duration in both hiPSC-CMs and mouse cardiomyocytes. Ranolazine, a selective INaL inhibitor, eliminated the QT and QTc intervals prolongation seen in p. D111Y trans-expressing mice.
Conclusions
In addition to peak INa, Tbx5 critically regulates INaL and the duration of repolarization in human cardiomyocytes. Our original results suggest that TBX5 variants associate with and modulate the intensity of the electrical phenotype in LQTS and BrS patients.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.

Cardiovasc Res: 16 Mar 2022; 118:1046-1060

Zebrafish Scube1 and Scube2 cooperate in promoting Vegfa signalling during embryonic vascularization.

Tsao KC, Lin YC, Chen YT, Lai SL, Yang RB
Aims
The secreted and membrane-anchored signal peptide-CUB-EGF domain-containing proteins (SCUBE) gene family composed of three members was originally identified from endothelial cells (ECs). We recently showed that membrane SCUBE2 binds vascular endothelial growth factor (VEGF) and acts as a co-receptor for VEGF receptor 2 to modulate EC migration, proliferation, and tube formation during postnatal and tumour angiogenesis. However, whether these SCUBE genes cooperate in modulating VEGF signalling 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 signalling 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 behaviours and formation of functional vessels during zebrafish embryonic development.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.

Cardiovasc Res: 16 Mar 2022; 118:1074-1087

Influence of sex on intracellular calcium homoeostasis 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), favouring 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 homoeostasis 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.

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

Cardiovasc Res: 16 Mar 2022; 118:1033-1045

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 in the absence of glucose is less important 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 shown that ketone bodies 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: journals.permissions@oup.com.

Cardiovasc Res: 15 Mar 2022; 118:977-987

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 signalling 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 signalling pathway inhibition include an increase in arterial pressure, left ventricular dysfunction facilitating the development of heart failure, thromboembolic events including pulmonary embolism and stroke, and myocardial infarction. Sex steroids, such as androgens, progestins, and oestrogens 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 therapy, 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 to personalized medicine in men and women requiring anti-angiogenic therapy to reduce adverse effects and to improve therapeutic efficacy.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.

Cardiovasc Res: 15 Mar 2022; 118:988-1003

The role of autophagy in cardiovascular pathology.

Gatica D, Chiong M, Lavandero S, Klionsky DJ
Macroautophagy/autophagy is a conserved catabolic recycling pathway in which cytoplasmic components are sequestered, degraded, and recycled to survive various stress conditions. Autophagy dysregulation has been observed and linked with the development and progression of several pathologies, including cardiovascular diseases, the leading cause of death in the developed world. In this review, we aim to provide a broad understanding of the different molecular factors that govern autophagy regulation and how these mechanisms are involved in the development of specific cardiovascular pathologies, including ischemic and reperfusion injury, myocardial infarction, cardiac hypertrophy, cardiac remodelling, and heart failure.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.

Cardiovasc Res: 15 Mar 2022; 118:934-950

SIRT1 in the cardiomyocyte counteracts doxorubicin-induced cardiotoxicity via regulating histone H2AX.

Kuno A, Hosoda R, Tsukamoto M, Sato T, ... Iwahara N, Horio Y
Aims
Cardiotoxicity by doxorubicin predicts worse prognosis of patients. Accumulation of damaged DNA has been implicated in doxorubicin-induced cardiotoxicity. SIRT1, an NAD+-dependent histone/protein deacetylase, protects cells by deacetylating target proteins. We investigated whether SIRT1 counteracts doxorubicin-induced cardiotoxicity by mediating Ser139 phosphorylation of histone H2AX, a critical signal of the DNA damage response.
Methods and results
Doxorubicin (5 mg/kg per week, x4) was administered to mice with intact SIRT1 (Sirt1f/f) and mice that lack SIRT1 activity in cardiomyocytes (Sirt1f/f; MHCcre/+). Reductions in left ventricular fractional shortening and ejection fraction by doxorubicin treatment were more severe in Sirt1f/f; MHCcre/+ than in Sirt1f/f. Myocardial expression level of type-B natriuretic peptide was 2.5-fold higher in Sirt1f/f; MHCcre/+ than in Sirt1f/f after doxorubicin treatment. Sirt1f/f; MHCcre/+ showed larger fibrotic areas and higher nitrotyrosine levels in the heart after doxorubicin treatment. Although doxorubicin-induced DNA damage evaluated by TUNEL staining was enhanced in Sirt1f/f; MHCcre/+, the myocardium from Sirt1f/f; MHCcre/+ showed blunted Ser139 phosphorylation of H2AX by doxorubicin treatment. In H9c2 cardiomyocytes, SIRT1 knockdown attenuated Ser139 phosphorylation of H2AX, increased DNA damage, and enhanced caspase-3 activation under doxorubicin treatment. Immunostaining revealed that acetylation level of H2AX at Lys5 was higher in hearts from Sirt1f/f; MHCcre/+. In H9c2 cells, acetyl-Lys5-H2AX level was increased by SIRT1 knockdown and reduced by SIRT1 overexpression. Ser139 phosphorylation in response to doxorubicin treatment was blunted in a mutant H2AX with substitution of Lys5 to Gln (K5Q) that mimics acetylated lysine compared with that in wild-type H2AX. Expression of K5Q-H2AX as well as S139A-H2AX, which cannot be phosphorylated at Ser139, augmented doxorubicin-induced caspase-3 activation. Treatment of mice with resveratrol, a SIRT1 activator, attenuated doxorubicin-induced cardiac dysfunction, which was associated with a reduction in acetyl-Lys5-H2AX level and a preserved phospho-Ser139-H2AX level.
Conclusion
These findings suggest that SIRT1 counteracts doxorubicin-induced cardiotoxicity by mediating H2AX phosphorylation through its deacetylation in cardiomyocytes.
Translational perspective
Doxorubicin-induced cardiotoxicity limits the further use of doxorubicin for cancer treatment and determines prognosis of patients. This work shows for the first time the protective effect of SIRT1, an NAD+-dependent deacetylase, on doxorubicin-induced cardiotoxicity using a genetically modified mouse model. We identified histone H2AX as a target of SIRT1 for proper DNA damage response. Therefore, DNA repair by SIRT1 could be a potential therapeutic target to attenuate doxorubicin cardiotoxicity. SIRT1 activity may also help to predict a risk of developing cardiotoxicity in patients treated with doxorubicin.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2022. For permissions, please email: journals.permissions@oup.com.

Cardiovasc Res: 07 Mar 2022; epub ahead of print

Side effects of statins-from pathophysiology and epidemiology to diagnostic and therapeutic implications.

Ruscica M, Ferri N, Banach M, Sirtori CR, Corsini A
Treatment with statins, inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase, has proven beneficial preventive effects on cardiovascular events. However, discontinuation due to intolerance and nonadherence remain two of the major gaps in both primary and secondary prevention. This leads many patients with high-risk of atherosclerotic cardiovascular disease (ASCVD) to be inadequately treated or not to achieve the target lipid level goals, and as consequence they undergo an increased risk of cardiovascular events. The aim of this review is thus to give an overview of the reasons for discontinuation and on the possible mechanisms behind them. Although statins, as a class, are generally safe, they are associated with an increased risk of diabetes mellitus and hepatic transaminase elevations. Incidence of cataracts or cognitive dysfunction and others presented in the literature (e.g., proteinuria and haematuria) have been never confirmed to have a causal link. Conversely, debated remains the effect on myalgia. Muscle side effects are the most commonly reported, although myalgia is still believed by some to be the result of a nocebo/drucebo effect. Concerning mechanisms behind these side effects no clear conclusions have been reached. Thus, if on one side it is important to identify individuals either at higher risk to develop a side effect, or with confirmed risk factors and conditions of statin intolerance, on the other side alternative strategies should be identified to avoid an increased ASCVD risk.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2022. For permissions please email: journals.permissions@oup.com.

Cardiovasc Res: 02 Mar 2022; epub ahead of print

Properties and fate of human mesenchymal stem cells upon miRNA let-7f-promoted recruitment to atherosclerotic plaques.

Egea V, Megens RTA, Santovito D, Wantha S, ... Weber C, Ries C
Aims
Atherosclerosis is a chronic inflammatory disease of the arteries leading to the formation of atheromatous plaques. Human mesenchymal stem cells (hMSCs) are recruited from the circulation into plaques where in response to their environment they adopt a phenotype with immunomodulatory properties. However, the mechanisms underlying hMSC function in these processes are unclear. Recently, we described that miRNA let-7f controls hMSC invasion guided by inflammatory cytokines and chemokines. Here, we investigated the role of let-7f in hMSC tropism to human atheromas and the effects of the plaque microenvironment on cell fate and release of soluble factors.
Methods and results
Incubation of hMSCs with LL-37, an antimicrobial peptide abundantly found in plaques, increased biosynthesis of let-7f and N-formyl peptide receptor 2 (FPR2), enabling chemotactic invasion of the cells towards LL-37, as determined by qRT-PCR, flow cytometry, and cell invasion assay analysis. In an Apoe  -/- mouse model of atherosclerosis, circulating hMSCs preferentially adhered to athero-prone endothelium. This property was facilitated by elevated levels of let-7f in the hMSCs, as assayed by ex vivo artery perfusion and 2-photon laser scanning microscopy. Exposure of hMSCs to homogenized human atheromatous plaque material considerably induced the production of various cytokines, chemokines, matrix metalloproteinases, and tissue inhibitors of metalloproteinases, as studied by PCR array and Western blot analysis. Moreover, exposure to human plaque extracts elicited differentiation of hMSCs into cells of the myogenic lineage, suggesting a potentially plaque-stabilizing effect.
Conclusions
Our findings indicate that let-7f promotes hMSC tropism toward atheromas through the LL-37/FPR2 axis and demonstrate that hMSCs upon contact with human plaque environment develop a potentially athero-protective signature impacting the pathophysiology of atherosclerosis.
Translational perspective
Human mesenchymal stem cells (hMSCs) represent a promising therapeutic approach in various pathophysiological processes associated with inflammation including atherosclerosis. The current knowledge about the mechanisms of hMSC tropism towards human atherosclerotic plaques and their beneficial effects at the site is poor. Bridging this gap is essential for clinical application of hMSCs. Our work provides insight into the contribution of microRNA let-7f in hMSC recruitment to atheroprone areas, where hMSCs display athero-protective potential by releasing immunomodulatory factors and differentiating towards plaque-stabilizing cells. Our findings highlight circulating hMSCs as a possible therapeutic strategy for the stabilization of atherosclerotic plaques.

© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 02 Mar 2022; epub ahead of print

Mapping the developing human cardiac endothelium at single cell resolution identifies MECOM as a regulator of arteriovenous gene expression.

McCracken IR, Dobie R, Bennett M, Passi R, ... Brittan M, Baker AH
Aims
Coronary vasculature formation is a critical event during cardiac development, essential for heart function throughout perinatal and adult life. However, current understanding of coronary vascular development has largely been derived from transgenic mouse models. The aim of this study was to characterise the transcriptome of the human fetal cardiac endothelium using single-cell RNA sequencing (scRNA-seq) to provide critical new insights into the cellular heterogeneity and transcriptional dynamics that underpin endothelial specification within the vasculature of the developing heart.
Methods and results
We acquired scRNA-seq data of over 10,000 fetal cardiac endothelial cells (EC), revealing divergent EC subtypes including endocardial, capillary, venous, arterial, and lymphatic populations. Gene regulatory network analyses predicted roles for SMAD1 and MECOM in determining the identity of capillary and arterial populations, respectively. Trajectory inference analysis suggested an endocardial contribution to the coronary vasculature and subsequent arterialisation of capillary endothelium accompanied by increasing MECOM expression. Comparative analysis of equivalent data from murine cardiac development demonstrated that transcriptional signatures defining endothelial subpopulations are largely conserved between human and mouse. Comprehensive characterisation of the transcriptional response to MECOM knockdown in human embryonic stem cell-derived EC (hESC-EC) demonstrated an increase in the expression of non-arterial markers, including those enriched in venous EC.
Conclusions
scRNA-seq of the human fetal cardiac endothelium identified distinct EC populations. A predicted endocardial contribution to the developing coronary vasculature was identified, as well as subsequent arterial specification of capillary EC. Loss of MECOM in hESC-EC increased expression of non-arterial markers, suggesting a role in maintaining arterial EC identity.
Translational perspective
Endogenous blood vessel formation in the adult heart following myocardial infarction is insufficient to support adequate survival of the remaining myocardium, often ultimately leading to heart failure. Improved understanding of the mechanisms regulating human coronary vessel formation is required to inform therapeutic strategies to reactivate developmental pathways promoting therapeutic angiogenesis in patients. We applied scRNA-seq to map the transcriptome of the endothelium of the developing human heart. We identified novel transcriptional signatures underlying the cellular heterogeneity and dynamic changes occurring within the developing cardiac endothelium. This included identifying and validating MECOM as a novel regulator of arterial EC identity which may serve as a target for therapeutic neovascularization.

© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 24 Feb 2022; epub ahead of print

Renin, aldosterone, the aldosterone-to-renin ratio, and incident hypertension among normotensive subjects from the general population.

Arnold N, Hermanns IM, Schulz A, Hahad O, ... Münzel T, Wild PS
Aims
To investigate the predictive ability of direct plasma renin and aldosterone concentrations as well as their ratio (aldosterone-to-renin (ARR)) for incident hypertension in the general population.
Methods and results
Concentration of renin and aldosterone were measured by a chemiluminescence immunoassay (CLIA) using the fully-automated LIAISON® platform (DiaSorin) among 5,362 participants of the population-based Gutenberg Health Study, who were normotensive and had no clinically-overt CVD at baseline. During a follow-up period of five years, 18.6% (n = 996) developed a new-onset hypertension. Comparing extreme quartiles of biomarker distribution, the relative risk (RR) for incident arterial hypertension was found to be 1.58 (95% confidence interval (CI) 1.25-2.00; p = 0.00015; Q1 vs Q4ref) for renin; 1.29 (95% CI 1.05-1.59, p = 0.018; Q4 vs Q1ref) for aldosterone and 1.70 (95%CI 1.33-2.12; p < 0.0001; Q4 vs Q1ref) for ARR after multivariable adjustment in men. In females, only high ARR was independently predictive for incident hypertension over five years (RR 1.29 (95% CI 1.04-1.62); p = 0.024). Even in the subgroup of individuals having biomarker concentrations within the reference range, high ARR was predictive for new-onset hypertension in men (RR 1.44 (95%CI 1.13-1.83); p = 0.003). Finally, synergistic effects of co-prevalent obesity and ARR on incident hypertension were also demonstrated, resulting in markedly higher risk estimates as seen for biomarker alone (RR of 2.70 (95% 2.05-3.6) for Q4 of ARR and having BMI ≥ 30 kg/m2 vs low ARR (Q1ref) and normal weight; p < 0.0001).
Conclusion
Among normotensives from the general population ARR possesses a stronger predictive value for incident hypertension than renin or aldosterone alone. The prediction of arterial hypertension by ARR was even stronger in obese subjects.
Translational perspective
These findings may help in a better understanding of importance of aldosterone-renin imbalance for the development of new-onset hypertension among normotensive subject and identify individuals at greatest risk, who probably required more intensive preventive measures.

© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 22 Feb 2022; epub ahead of print

Gene editing reverses arrhythmia susceptibility in humanized PLN-R14del mice: modeling a European cardiomyopathy with global impact.

Dave J, Raad N, Mittal N, Zhang L, ... Hajjar RJ, Stillitano F
Aims
A mutation in the phospholamban (PLN) gene, leading to deletion of Arg14 (R14del), has been associated with malignant arrhythmias and ventricular dilation. Identifying pre-symptomatic carriers with vulnerable myocardium is crucial because arrhythmia can result in sudden cardiac death, especially in young adults with PLN-R14del mutation.This study aimed at assessing the efficiency and efficacy of in vivo genome editing, using CRISPR/Cas9 and a cardiotropic adeno-associated virus (AAV9), in improving cardiac function in young adult mice expressing the human PLN-R14del.
Methods and results
Humanized mice were generated expressing human wild-type (hPLN-WT) or mutant (hPLN-R14del) PLN in the heterozygous state, mimicking human carriers. Cardiac magnetic resonance imaging at 12 weeks of age showed bi-ventricular dilation and increased stroke volume in mutant vs. WT mice, with no deficit in ejection fraction or cardiac output. Challenge of ex vivo hearts with isoproterenol and rapid pacing unmasked higher propensity for sustained ventricular tachycardia (VT) in hPLN-R14del relative to hPLN-WT. Specifically, the VT threshold was significantly reduced (20.3±1.2 Hz in hPLN-R14del vs. 25.7±1.3 Hz in WT, p < 0.01) reflecting higher arrhythmia burden. To inactivate the R14del allele, mice were tail-vein-injected with AAV9.CRISPR/Cas9/gRNA or AAV9 empty capsid (controls). CRISPR-Cas9 efficiency was evaluated by droplet digital PCR and NGS-based amplicon sequencing. In vivo gene editing significantly reduced end diastolic and stroke volumes in hPLN-R14del CRISPR-treated mice compared to controls. Susceptibility to VT was also reduced, as the VT threshold was significantly increased relative to controls (30.9±2.3 Hz vs. 21.3±1.5 Hz; p < 0.01).
Conclusions
This study is the first to show that disruption of hPLN-R14del allele by AAV9- CRISPR/Cas9 improves cardiac function and reduces VT susceptibility in humanized PLN-R14del mice, offering preclinical evidence for translatable approaches to therapeutically suppress the arrhythmogenic phenotype in human patients with PLN-R14del disease.
Translational perspective
The phospholamban R14del mutation causes dilated and arrhythmogenic cardiomyopathies, with increased risk of malignant ventricular arrhythmias in young adult carriers. With few available therapeutic options, heart transplantation is often the ultimate treatment. This study presents the first humanized mouse model of PLN-R14del disease, reveals the ability to detect abnormal cardiac function and increased arrhythmogenic vulnerability in pre-symptomatic hPLN-R14del mice, and demonstrates that allele-specific disruption of R14del using in vivo AAV9/CRISPR-Cas9 reverses the disease phenotype. This preclinical study offers promising translatable approaches to detect and therapeutically suppress the arrhythmogenic phenotype in patients with PLN-R14del disease and potentially other inherited cardiomyopathies.

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Cardiovasc Res: 21 Feb 2022; epub ahead of print