Approaches to treat pulmonary arterial hypertension by targeting bmpr2 - from cell membrane to nucleus.

Dunmore BJ, Jones RJ, Toshner MR, Upton PD, Morrell NW

Pulmonary arterial hypertension (PAH) is estimated to affect between 10-50 people per million worldwide. The lack of cure and devastating nature of the disease means that treatment is crucial to arrest rapid clinical worsening. Current therapies are limited by their focus on inhibiting residual vasoconstriction rather than targeting key regulators of the cellular pathology. Potential disease-modifying therapies may come from research directed towards causal pathways involved in the cellular and molecular mechanisms of disease. It is widely acknowledged, that targeting reduced expression of the critical bone morphogenetic protein type-2 receptor (BMPR2) and its associated signalling pathways is a compelling therapeutic avenue to explore. In this review we highlight the advances that have been made in understanding this pathway and the therapeutics that are being tested in clinical trials and the clinic to treat PAH.

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

Cardiovasc Res: 04 Jan 2021; epub ahead of print

Stroke risk prediction in patients with atrial fibrillation with and without rheumatic heart disease.

Benz AP, Healey JS, Chin A, Commerford P, ... Yusuf S, Connolly SJ
Aims
Patients with atrial fibrillation (AF) and rheumatic heart disease (RHD), especially mitral stenosis, are assumed to be at high risk of stroke, irrespective of other factors. We aimed to re-evaluate stroke risk factors in a contemporary cohort of AF patients.
Methods and results
We analyzed data of 15,400 AF patients presenting to an emergency department and who were enrolled in the global RE-LY AF registry, representing 47 countries from all inhabited continents. Follow-up occurred at 1 year after enrollment. A total of 1,788 (11.6%) patients had RHD. These patients were younger (51.4 ± 15.7 vs. 67.8 ± 13.6 years), more likely to be female (66.2% vs. 44.7%) and had a lower mean CHA2DS2-VASc score (2.1 ± 1.7 vs. 3.7 ± 2.2) as compared to patients without RHD (all p < 0.001). Significant mitral stenosis (average mean transmitral gradient 11.5 ± 6.5 mmHg) was the predominant valve lesion in those with RHD (59.6%). Patients with RHD had a higher baseline rate of anticoagulation use (60.4% vs. 45.2%, p < 0.001). Unadjusted stroke rates at 1 year were 2.8% and 4.1% for patients with and without RHD, respectively. The performance of the CHA2DS2-VASc score was modest in both groups (stroke at 1 year, c-statistics 0.69, 95% confidence interval [CI] 0.60-0.78 and 0.63, 95% CI 0.61-0.66, respectively). In the overall cohort, advanced age, female sex, prior stroke, tobacco use and non-use of anticoagulation were predictors for stroke (all p < 0.05). Mitral stenosis was not associated with stroke risk (adjusted odds ratio 1.07, 95% CI 0.67-1.72, p = 0.764).
Conclusions
The performance of the CHA2DS2-VASc score was modest in AF patients both with and without RHD. In this cohort, moderate-to-severe mitral stenosis was not an independent risk factor for stroke.
Translational perspective
Based on studies conducted several decades ago, the presence of moderate-to-severe mitral stenosis has been associated with a very high risk of stroke in patients with AF. Our results, based on a large, global sample of contemporary patients with AF that contained a significant proportion of individuals with RHD, challenge the assumption that mitral stenosis is a major, independent risk factor for stroke. The performance of the widely used CHA2DS2-VASc score was modest in both patients with and without RHD. At least one ongoing randomized trial is evaluating the optimal antithrombotic strategy in patients with AF and RHD.

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

Cardiovasc Res: 01 Jan 2021; epub ahead of print

Hydralazine protects the heart against acute ischemia/reperfusion injury by inhibiting Drp1-mediated mitochondrial fission.

Kalkhoran SB, Kriston-Vizi J, Hernandez-Resendiz S, Crespo-Avilan GE, ... Lim SY, Hausenloy DJ
Aims
Genetic and pharmacological inhibition of mitochondrial fission induced by acute myocardial ischaemia/reperfusion injury has been shown to reduce myocardial infarct size. The clinically used anti-hypertensive and heart failure medication, hydralazine, is known to have anti-oxidant and anti-apoptotic effects. Here, we investigated whether hydralazine confers acute cardioprotection by inhibiting Drp1-mediated mitochondrial fission.
Methods and results
Pre-treatment with hydralazine was shown to inhibit both mitochondrial fission and mitochondrial membrane depolarisation induced by oxidative stress in HeLa cells. In mouse embryonic fibroblasts (MEFs), pre-treatment with hydralazine attenuated mitochondrial fission and cell death induced by oxidative stress, but this effect was absent in MEFs deficient in the mitochondrial fission protein, Drp1. Molecular docking and surface plasmon resonance studies demonstrated binding of hydralazine to the GTPase domain of the mitochondrial fission protein, Drp1 (KD 8.6 ± 1.0 µM), and inhibition of Drp1 GTPase activity in a dose-dependent manner. In isolated adult murine cardiomyocytes subjected to simulated ischaemia/reperfusion injury (IRI), hydralazine inhibited mitochondrial fission, preserved mitochondrial fusion events, and reduced cardiomyocyte death (hydralazine 24.7 ± 2.5% vs control 34.1 ± 1.5%, P = 0.0012). In ex vivo perfused murine hearts subjected to acute IRI, pre-treatment with hydralazine reduced myocardial infarct size (as % left ventricle: hydralazine 29.6 ± 6.5% vs vehicle control 54.1 ± 4.9%, P = 0.0083), and in the murine heart subjected to in vivo IRI, the administration of hydralazine at reperfusion, decreased myocardial infarct size (as % area-at-risk: hydralazine 28.9 ± 3.0% vs vehicle control 58.2 ± 3.8%, P < 0.001).
Conclusion
We show that, in addition to its anti-oxidant and anti-apoptotic effects, hydralazine, confers acute cardioprotection by inhibiting IRI-induced mitochondrial fission, raising the possibility of repurposing hydralazine as a novel cardioprotective therapy for improving post-infarction outcomes.
Translational perspective
Hydralazine is used clinically as a treatment for patients with hypertension and chronic heart failure, and experimental studies have known it to have anti-oxidant and anti-apoptotic effects. In our study, we show that administration of hydralazine immediately prior to reperfusion inhibited ischaemia/reperfusion injury-induced mitochondrial fission, and reduced myocardial infarct size. These findings raise the possibility of repurposing hydralazine as a novel potential cardioprotective therapy, which can be administered to acute myocardial infarction patients immediately prior to reperfusion by primary percutaneous coronary intervention, to reduce myocardial infarct size and prevent heart failure.

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

Cardiovasc Res: 01 Jan 2021; epub ahead of print

Molecular mechanisms and clinical implications of multiple forms of mitophagy in the heart.

Saito T, Hamano K, Sadoshima J

Mitochondria, the primary ATP-producing organelles, are highly abundant in cardiomyocytes. Mitochondrial function readily deteriorates in the presence of stress and, thus, maintenance of mitochondrial quality is essential for sustaining pump function in the heart. Cardiomyocytes under stress attempt to maintain mitochondrial quality primarily through dynamic changes in their morphology, namely fission and fusion, degradation, and biogenesis. Mitophagy, a mitochondria-specific form of autophagy, is a major mechanism of degradation. The level of mitophagy is altered in stress conditions, which, in turn, significantly affects mitochondrial function, cardiomyocyte survival, and death and cardiac function. Thus, mitophagy has been emerging as a promising target for treatment of cardiac conditions. To develop specific interventions, modulating the activity of mitophagy in the heart, understanding how mitochondria are degraded in a given condition is important. Increasing lines of evidence suggest that there are multiple mechanisms by which mitochondria are degraded through mitophagy in the heart. For example, in addition to the well-established mechanism commonly utilized by general autophagy, involving Atg7 and LC3, recent evidence suggests that an alternative mechanism, independent of Atg7 and LC3, also mediates mitophagy in the heart. Here, we describe molecular mechanisms through which mitochondria are degraded in the heart and discuss their functional significance. We also discuss molecular interventions to modulate the activity of mitophagy and their potential applications for cardiac conditions.

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

Cardiovasc Res: 16 Dec 2020; epub ahead of print

Niacin protects against abdominal aortic aneurysm formation via GPR109A independent mechanisms: role of NAD+/nicotinamide.

Horimatsu T, Blomkalns AL, Ogbi M, Moses M, ... Weintraub NL, Kim HW
Aims
Chronic adventitial and medial infiltration of immune cells play an important role in the pathogenesis of abdominal aortic aneurysms (AAAs). Nicotinic acid (niacin) was shown to inhibit atherosclerosis by activating the anti-inflammatory G protein-coupled receptor GPR109A [also known as hydroxycarboxylic acid receptor 2 (HCA2)] expressed on immune cells, blunting immune activation and adventitial inflammatory cell infiltration. Here, we investigated the role of niacin and GPR109A in regulating AAA formation.
Methods and results
Mice were supplemented with niacin or nicotinamide, and AAA was induced by angiotensin II (AngII) infusion or calcium chloride (CaCl2) application. Niacin markedly reduced AAA formation in both AngII and CaCl2 models, diminishing adventitial immune cell infiltration, concomitant inflammatory responses, and matrix degradation. Unexpectedly, GPR109A gene deletion did not abrogate the protective effects of niacin against AAA formation, suggesting GPR109A-independent mechanisms. Interestingly, nicotinamide, which does not activate GPR109A, also inhibited AAA formation and phenocopied the effects of niacin. Mechanistically, both niacin and nicotinamide supplementation increased nicotinamide adenine dinucleotide (NAD+) levels and NAD+-dependent Sirt1 activity, which were reduced in AAA tissues. Furthermore, pharmacological inhibition of Sirt1 abrogated the protective effect of nicotinamide against AAA formation.
Conclusion
Niacin protects against AAA formation independent of GPR109A, most likely by serving as an NAD+ precursor. Supplementation of NAD+ using nicotinamide-related biomolecules may represent an effective and well-tolerated approach to preventing or treating AAA.

© The Author(s) 2019. Published by Oxford University Press on behalf of the European Society of Cardiology.

Cardiovasc Res: 30 Nov 2020; 116:2226-2238

Machine learning to predict the long-term risk of myocardial infarction and cardiac death based on clinical risk, coronary calcium, and epicardial adipose tissue: a prospective study.

Commandeur F, Slomka PJ, Goeller M, Chen X, ... Berman DS, Dey D
Aims
Our aim was to evaluate the performance of machine learning (ML), integrating clinical parameters with coronary artery calcium (CAC), and automated epicardial adipose tissue (EAT) quantification, for the prediction of long-term risk of myocardial infarction (MI) and cardiac death in asymptomatic subjects.
Methods and results
Our study included 1912 asymptomatic subjects [1117 (58.4%) male, age: 55.8 ± 9.1 years] from the prospective EISNER trial with long-term follow-up after CAC scoring. EAT volume and density were quantified using a fully automated deep learning method. ML extreme gradient boosting was trained using clinical co-variates, plasma lipid panel measurements, risk factors, CAC, aortic calcium, and automated EAT measures, and validated using repeated 10-fold cross validation. During mean follow-up of 14.5 ± 2 years, 76 events of MI and/or cardiac death occurred. ML obtained a significantly higher AUC than atherosclerotic cardiovascular disease (ASCVD) risk and CAC score for predicting events (ML: 0.82; ASCVD: 0.77; CAC: 0.77, P < 0.05 for all). Subjects with a higher ML score (by Youden\'s index) had high hazard of suffering events (HR: 10.38, P < 0.001); the relationships persisted in multivariable analysis including ASCVD-risk and CAC measures (HR: 2.94, P = 0.005). Age, ASCVD-risk, and CAC were prognostically important for both genders. Systolic blood pressure was more important than cholesterol in women, and the opposite in men.
Conclusions
In this prospective study, machine learning used to integrate clinical and quantitative imaging-based variables significantly improves prediction of MI and cardiac death compared with standard clinical risk assessment. Following further validation, such a personalized paradigm could potentially be used to improve cardiovascular risk assessment.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: [email protected]

Cardiovasc Res: 30 Nov 2020; 116:2216-2225

Insights into therapeutic products, preclinical research models and clinical trials in cardiac regenerative and reparative medicine: where are we now and the way ahead. Current opinion paper of the ESC working group on cardiovascular regenerative and reparative medicine.

Grigorian SL, Sanz-Ruiz R, Climent A, Badimon L, ... Zimmermann WH, Fernández-Avilés F

Great expectations have been set around the clinical potential of regenerative and reparative medicine in the treatment of cardiovascular diseases (i.e., in particular heart failure [HF]). Initial excitement, spurred by encouraging preclinical data, resulted in a rapid translation into clinical research. The sobering outcome of the resulting clinical trials suggests that preclinical testing may have been insufficient to predict clinical outcome. Number of barriers for clinical translation include the inherent variability of the biological products and difficulties to develop potency and quality assays, insufficient rigor of the preclinical research and reproducibility of the results, manufacturing challenges and scientific irregularities reported in the last years. The failure to achieve clinical success led to an increased scrutiny and skepticism as to the clinical readiness of stem cells and gene therapy products among clinicians, industry stakeholders and funding bodies. The present impasse has attracted the attention of some of the most active research groups in the field, which were then summoned to analyze the position of the field and tasked to develop a strategy, to re-visit the undoubtedly promising future of cardiovascular regenerative and reparative medicine, based on lessons learned over the past two decades. During the scientific retreat of the ESC Working Group on Cardiovascular Regenerative and Reparative Medicine (CARE) in November 2018, the most relevant and timely research aspects in regenerative and/or reparative medicine were presented and critically discussed, with the aim to lay out a strategy for the future development of the field. We report herein the main ideas and conclusions of that meeting.

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

Cardiovasc Res: 30 Nov 2020; epub ahead of print

Obesity, kidney dysfunction and inflammation: interactions in hypertension.

Hall JE, Mouton A, da Silva AA, Omoto ACM, ... Li X, do Carmo JM

Obesity contributes 65-75% of the risk for human primary (essential) hypertension which is a major driver of cardiovascular and kidney diseases. Kidney dysfunction, associated with increased renal sodium reabsorption and compensatory glomerular hyperfiltration, plays a key role in initiating obesity-hypertension and target organ injury. Mediators of kidney dysfunction and increased blood pressure include 1) elevated renal sympathetic nerve activity (RSNA); 2) increased antinatriuretic hormones such as angiotensin II and aldosterone; 3) relative deficiency of natriuretic hormones; 4) renal compression by fat in and around the kidneys; 5) activation of innate and adaptive immune cells that invade tissues throughout the body, producing inflammatory cytokines/chemokines that contribute to vascular and target organ injury, and exacerbate hypertension. These neurohormonal, renal, and inflammatory mechanisms of obesity-hypertension are interdependent. For example, excess adiposity increases the adipocyte-derived cytokine leptin which increases RSNA by stimulating the central nervous system proopiomelanocortin-melanocortin 4 receptor pathway. Excess visceral, perirenal and renal sinus fat compress the kidneys which, along with increased RSNA, contribute to renin-angiotensin-aldosterone system activation, although obesity may also activate mineralocorticoid receptors independent of aldosterone. Prolonged obesity, hypertension, metabolic abnormalities, and inflammation cause progressive renal injury, making hypertension more resistant to therapy and often requiring multiple antihypertensive drugs and concurrent treatment of dyslipidemia, insulin resistance, diabetes, and inflammation. More effective anti-obesity drugs are needed to prevent the cascade of cardiorenal, metabolic, and immune disorders that threaten to overwhelm health care systems as obesity prevalence continues to increase.

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

Cardiovasc Res: 30 Nov 2020; epub ahead of print

Network Medicine In Cardiovascular Research.

Lee LY, Pandey AK, Maron BA, Loscalzo J

The ability to generate multi-omics data coupled with deeply characterizing the clinical phenotype of individual patients promises to improve understanding of complex cardiovascular pathobiology. There remains an important disconnection between the magnitude and granularity of these data and our ability to improve phenotype-genotype correlations for complex cardiovascular diseases. This shortcoming may be due to limitations associated with traditional reductionist analytical methods, which tend to emphasize a single molecular event in the pathogenesis of diseases more aptly characterized by crosstalk between overlapping molecular pathways. Network medicine is a rapidly growing discipline that considers diseases as the consequences of perturbed interactions between multiple interconnected biological components. This powerful integrative approach has enabled a number of important discoveries in complex disease mechanisms. In this review, we introduce the basic concepts of network medicine and highlight specific examples by which this approach has accelerated cardiovascular research. We also review how network medicine is well-positioned to promote rational drug design for patients with cardiovascular diseases, with particular emphasis on advancing precision medicine.

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

Cardiovasc Res: 08 Nov 2020; epub ahead of print

Numbers and phenotype of non-classical CD14dimCD16+ monocytes are predictors of adverse clinical outcome in patients with coronary artery disease and severe SARS-CoV-2 infection.

Mueller KAL, Langnau C, Günter M, Pöschel S, ... Gawaz MP, Autenrieth SE
Aims 
To elucidate the prognostic role of monocytes in the immune response of patients with coronary artery disease (CAD) at risk for life-threatening heart and lung injury as major complications of SARS-CoV-2 infection.
Methods and results 
From February to April 2020, we prospectively studied a cohort of 96 participants comprising 47 consecutive patients with CAD and acute SARS-CoV-2 infection (CAD + SARS-CoV-2), 19 CAD patients without infections, and 30 healthy controls. Clinical assessment included blood sampling, echocardiography, and electrocardiography within 12 h of admission. Respiratory failure was stratified by the Horovitz Index (HI) as moderately/severely impaired when HI ≤200 mmHg. The clinical endpoint (EP) was defined as HI ≤200 mmHg with subsequent mechanical ventilation within a follow-up of 30 days. The numbers of CD14dimCD16+ non-classical monocytes in peripheral blood were remarkably low in CAD + SARS-CoV-2 compared with CAD patients without infection and healthy controls (P < 0.0001). Moreover, these CD14dimCD16 monocytes showed decreased expression of established markers of adhesion, migration, and T-cell activation (CD54, CD62L, CX3CR1, CD80, and HLA-DR). Decreased numbers of CD14dimCD16+ monocytes were associated with the occurrence of EP. Kaplan-Meier curves illustrate that CAD + SARS-CoV-2 patients with numbers below the median of CD14dimCD16+ monocytes (median 1443 cells/mL) reached EP significantly more often compared to patients with numbers above the median (log-rank 5.03, P = 0.025).
Conclusion 
Decreased numbers of CD14dimCD16+ monocytes are associated with rapidly progressive respiratory failure in CAD + SARS-CoV-2 patients. Intensified risk assessments comprising monocyte sub- and phenotypes may help to identify patients at risk for respiratory failure.

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

Cardiovasc Res: 02 Nov 2020; epub ahead of print

Role of the vascular endothelial sodium channel activation in the genesis of pathologically increased cardiovascular stiffness.

Hill MA, Jaisser F, Sowers JR

Cardiovascular (CV) stiffening represents a complex series of events evolving from pathological changes in individual cells of the vasculature and heart which leads to overt tissue fibrosis. While vascular stiffening occurs naturally with ageing it is accelerated in states of insulin (INS) resistance, such as obesity and type 2 diabetes. CV stiffening is clinically manifested as increased arterial pulse wave velocity and myocardial fibrosis-induced diastolic dysfunction. A key question that remains is how are these events mechanistically linked. In this regard, heightened activation of vascular mineralocorticoid receptors (MR) and hyperinsulinaemia occur in obesity and INS resistance states. Further, a downstream mediator of MR and INS receptor activation, the endothelial cell Na+ channel (EnNaC), has recently been identified as a key molecular determinant of endothelial dysfunction and CV fibrosis and stiffening. Increased activity of the EnNaC results in a number of negative consequences including stiffening of the cortical actin cytoskeleton in endothelial cells, impaired endothelial NO release, increased oxidative stress-meditated NO destruction, increased vascular permeability, and stimulation of an inflammatory environment. Such endothelial alterations impact vascular function and stiffening through regulation of vascular tone and stimulation of tissue remodelling including fibrosis. In the case of the heart, obesity and INS resistance are associated with coronary vascular endothelial stiffening and associated reductions in bioavailable NO leading to heart failure with preserved systolic function (HFpEF). After a brief discussion on mechanisms leading to vascular stiffness per se, this review then focuses on recent findings regarding the role of INS and aldosterone to enhance EnNaC activity and associated CV stiffness in obesity/INS resistance states. Finally, we discuss how coronary artery-mediated EnNaC activation may lead to cardiac fibrosis and HFpEF, a condition that is especially pronounced in obese and diabetic females.

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

Cardiovasc Res: 02 Nov 2020; epub ahead of print

The role of CD36 in cardiovascular disease.

Shu H, Peng Y, Hang W, Nie J, Zhou N, Wang DW

CD36, also known as the scavenger receptor B2, is a multifunctional receptor widely expressed in various organs. CD36 plays a crucial role in the uptake of long-chain fatty acids, the main metabolic substrate in myocardial tissue. The maturation and transportation of CD36 is regulated by post-translational modifications, including phosphorylation, ubiquitination, glycosylation, and palmitoylation. CD36 is decreased in pathological cardiac hypertrophy caused by ischaemia-reperfusion and pressure overload, and increased in diabetic cardiomyopathy and atherosclerosis. Deficiency of CD36 alleviates diabetic cardiomyopathy and atherosclerosis, while overexpression of CD36 eliminates ischaemia-reperfusion damage, together suggesting that CD36 is closely associated with the progression of cardiovascular diseases and may be a new therapeutic target. This review summarizes the regulation and post-translational modifications of CD36 and evaluates its role in cardiovascular diseases and its potential as a therapeutic target.

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

Cardiovasc Res: 02 Nov 2020; epub ahead of print

Cell senescence: basic mechanisms and the need for computational networks in vascular ageing.

Regnault V, Challande P, Pinet F, Li Z, Lacolley P

This review seeks to provide an update of the mechanisms of vascular cell senescence, from newly identified molecules to arterial ageing phenotypes, and finally to present a computational approach to connect these selected proteins in biological networks. We will discuss current key signalling and gene expression pathways by which these focus proteins and networks drive normal and accelerated vascular ageing. We also review the possibility that senolytic drugs, designed to restore normal cell differentiation and function, could effectively treat multiple age-related vascular diseases. Finally, we discuss how cell senescence is both a cause and a consequence of vascular ageing because of the possible feedback controls between identified networks.

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

Cardiovasc Res: 02 Nov 2020; epub ahead of print

Heart Regeneration - Beyond New Muscle And Vessels.

Sayers JR, Riley PR

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

© The Author(s) 2020. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: [email protected]

Cardiovasc Res: 02 Nov 2020; epub ahead of print

Off-target effects of SGLT2 blockers: empagliflozin does not inhibit Na+/H+ exchanger-1 or lower [Na+]i in the heart.

Chung YJ, Park KC, Tokar S, Eykyn TR, ... Swietach P, Shattock MJ
Aims
Empagliflozin (EMPA) is a potent inhibitor of the renal sodium-glucose cotransporter 2 (SGLT2) and an effective treatment for type-2 diabetes. In patients with diabetes and heart failure, EMPA has cardioprotective effects independent of improved glycaemic control, despite SGLT2 not being expressed in the heart. A number of non-canonical mechanisms have been proposed to explain these cardiac effects, most notably an inhibitory action on cardiac Na+/H+ exchanger 1 (NHE1), causing a reduction in intracellular [Na+] ([Na+]i). However, at resting intracellular pH (pHi), NHE1 activity is very low and its pharmacological inhibition is not expected to meaningfully alter steady-state [Na+]i. We re-evaluate this putative EMPA target by measuring cardiac NHE1 activity.
Methods and results
The effect of EMPA on NHE1 activity was tested in isolated rat ventricular cardiomyocytes from measurements of pHi recovery following an ammonium pre-pulse manoeuvre, using cSNARF1 fluorescence imaging. Whereas 10 µM cariporide produced near-complete inhibition, there was no evidence for NHE1 inhibition with EMPA treatment (1, 3, 10 or 30 µM). Intracellular acidification by acetate-superfusion evoked NHE1 activity and raised [Na+]i, reported by sodium binding benzofuran isophthalate (SBFI) fluorescence, but EMPA did not ablate this rise. EMPA (10 µM) also had no significant effect on the rate of cytoplasmic [Na+]i-rise upon superfusion of Na+-depleted cells with Na+-containing buffers. In Langendorff-perfused mouse, rat and guinea pig hearts, EMPA did not affect [Na+]i at baseline nor pHi recovery following acute acidosis, as measured by 23Na triple quantum filtered NMR and 31P NMR, respectively.
Conclusions
Our findings indicate that cardiac NHE1 activity is not inhibited by EMPA (or other SGLT2i\'s) and EMPA has no effect on [Na+]i over a wide range of concentrations, including the therapeutic dose. Thus, the beneficial effects of SGLT2i\'s in failing hearts should not be interpreted in terms of actions on myocardial NHE1 or intracellular [Na+].
Translational perspective
Heart failure remains a huge clinical burden. Clinical trials of SGLT2 inhibitors in patients with diabetes and heart failure have reported highly significant cardiovascular benefit that appears independent of improved glycaemic control. As SGLT2 is not expressed in the heart, the mechanism by which SGLT2 inhibitors are cardioprotective remains unknown. Understanding this mechanism is clearly essential as the use of SGLT2 inhibitors in non-diabetics is increasing and a better understanding may allow refinement of therapeutic approaches in both HFpEF and HFrEF. One suggested mechanism that has received significant attention, inhibition of cardiac Na+/H+ exchanger, is investigated here.

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

Cardiovasc Res: 01 Nov 2020; epub ahead of print

Updated Perspectives On Vascular Cell Specification And Pluripotent Stem Cell-Derived Vascular Organoids For Studying Vasculopathies.

Liu C, Niu K, Xiao Q

Vasculopathy is a pathological process occurring in the blood vessel wall, which could affect the haemostasis and physiological functions of all the vital tissues/organs and is one of the main underlying causes for a variety of human diseases including cardiovascular diseases. Current pharmacological interventions aiming to either delay or stop progression of vasculopathies are suboptimal, thus searching novel, targeted, risk-reducing therapeutic agents, or vascular grafts with full regenerative potential for patients with vascular abnormalities are urgently needed. Since first reported, pluripotent stem cells (PSCs), particularly human induced pluripotent stem cells, have open new avenue in all research disciplines including cardiovascular regenerative medicine and disease remodelling. Assisting with recent technological breakthroughs in tissue engineering, in vitro construction of tissue organoid made a tremendous stride in the past decade. In this review, we provide an update of the main signal pathways involved in vascular cell differentiation from human PSCs and an extensive overview of PSC-derived tissue organoids, highlighting the most recent discoveries in the field of blood vessel organoids as well as vascularization of other complex tissue organoids, with the aim of discussing the key cellular and molecular players in generating vascular organoids.

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

Cardiovasc Res: 01 Nov 2020; epub ahead of print

MicroRNA-mediated vascular intercellular communication is altered in chronic kidney disease.

Zietzer A, Steffen E, Niepmann S, Düsing P, ... Nickenig G, Jansen F
Aims
Chronic kidney disease (CKD) is an independent risk factor for the development of coronary artery disease (CAD). For both, CKD and CAD, the intercellular transfer of microRNAs (miR) through extracellular vesicles (EVs) is an important factor of disease development. Whether the combination of CAD and CKD affects endothelial function through cellular crosstalk of EV-incorporated miRs is still unknown.
Methods and results
Out of 172 screened CAD patients, 31 patients with CAD+CKD were identified and matched with 31 CAD patients without CKD. Additionally, 13 controls without CAD and CKD were included. Large EVs from CAD+CKD patients contained significantly lower levels of the vasculo-protective miR-130a-3p and miR-126-3p compared to CAD patients and controls. Flow cytometric analysis of plasma-derived EVs revealed significantly higher numbers of endothelial cell-derived EVs in CAD and CAD+CKD patients compared to controls. EVs from CAD+CKD patients impaired target human coronary artery endothelial cell (HCAEC) proliferation upon incubation in vitro. Consistent with the clinical data, treatment with the uremia toxin indoxyl sulfate (IS) reduced miR-130a-3p levels in HCAEC-derived EVs. EVs from IS-treated donor HCAECs reduced proliferation and reendothelialization in EV-recipient cells and induced an anti-angiogenic gene expression profile. In a mouse-experiment, intravenous treatment with EVs from IS-treated endothelial cells significantly impaired endothelial regeneration. On the molecular level, we found that IS leads to an upregulation of the heterogenous nuclear ribonucleoprotein U (hnRNPU), which retains miR-130a-3p in the cell leading to reduced vesicular miR-130a-3p export and impaired EV-recipient cell proliferation.
Conclusions
Our findings suggest that EV-miR-mediated vascular intercellular communication is altered in patients with CAD and CKD, promoting CKD-induced endothelial dysfunction.
Translational perspective
In the present study we identify a novel hnRNPU-dependent mechanism of how kidney disease and uremia reduce endothelial proliferation. HnRNPU can therefore be used as a target to influence vesicular microRNA levels to improve endothelial healing.

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

Cardiovasc Res: 01 Nov 2020; epub ahead of print

Neutralization of S100A4 induces stabilization of atherosclerotic plaques: role of smooth muscle cells.

Sakic A, Chaabane C, Ambartsumian N, Klingelhöfer J, ... Grigorian M, Bochaton-Piallat ML
Aims
During atherosclerosis, smooth muscle cells (SMCs) accumulate in the intima where they switch from a contractile to a synthetic phenotype. From porcine coronary artery, we isolated spindle-shaped (S) SMCs exhibiting features of the contractile phenotype and rhomboid (R) SMCs typical of the synthetic phenotype. S100A4 was identified as a marker of R-SMCs in vitro and intimal SMCs, in pig and man. S100A4 exhibits intra- and extracellular functions. In this study, we investigated the role of extracellular S100A4 in SMC phenotypic transition.
Methods and results
S-SMCs were treated with oligomeric recombinant S100A4 (oS100A4), which induced nuclear factor (NF)-κB activation. Treatment of S-SMCs with oS100A4 in combination with platelet-derived growth factor (PDGF)-BB induced a complete SMC transition toward a pro-inflammatory R-phenotype associated with NF-κB activation, through toll-like receptor-4. RNA sequencing of cells treated with oS100A4/PDGF-BB revealed a strong upregulation of pro-inflammatory genes and enrichment of transcription factor binding sites essential for SMC phenotypic transition. In a mouse model of established atherosclerosis, neutralization of extracellular S100A4 decreased area of atherosclerotic lesions, necrotic core, and CD68 expression and increased α-smooth muscle actin and smooth muscle myosin heavy chain expression.
Conclusion
We suggest that the neutralization of extracellular S100A4 promotes the stabilization of atherosclerotic plaques. Extracellular S100A4 could be a new target to influence the evolution of atherosclerotic plaques.
Translational perspective
Our studies indicate that extracellular S100A4 is causally related to atherosclerotic plaque progression putting it forward as a prospective therapeutic target for plaque stabilization and/or regression.

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

Cardiovasc Res: 01 Nov 2020; epub ahead of print

Titin-Truncating Mutations Associated With Dilated Cardiomyopathy Alter Length-Dependent Activation And Its Modulation Via Phosphorylation.

Vikhorev PG, Vikhoreva NN, Yeung W, Li A, ... de Tombe P, Marston SB
Aims
Dilated cardiomyopathy (DCM) is associated with mutations in many genes encoding sarcomere proteins. Truncating mutations in the titin gene TTN are the most frequent. Proteomic and functional characterisations are required to elucidate the origin of the disease and the pathogenic mechanisms of TTN-truncating variants.
Methods and results
We isolated myofibrils from DCM hearts carrying truncating TTN mutations and measured the Ca2+ sensitivity of force and its length dependence. Simultaneous measurement of force and adenosine triphosphate (ATP) consumption in skinned cardiomyocytes was also performed. Phosphorylation levels of troponin I (TnI) and myosin binding protein-C (MyBP-C) were manipulated using protein kinase A and λ phosphatase. mRNA sequencing was employed to overview gene expression profiles. We found that Ca2+ sensitivity of myofibrils carrying TTN mutations was significantly higher than in myofibrils from donor hearts. The length dependence of the Ca2+ sensitivity was absent in DCM myofibrils with TTN-truncating variants. No significant difference was found in the expression level of TTN mRNA between the DCM and donor groups. TTN exon usage and splicing were also similar. However, we identified downregulation of genes encoding Z-disk proteins, while the atrial-specific regulatory myosin light chain gene, MYL7, was upregulated in DCM patients with TTN-truncating variants.
Conclusion
Titin-truncating mutations lead to decreased length-dependent activation and increased elasticity of myofibrils. Phosphorylation levels of TnI and MyBP-C seen in the left ventricles are essential for the length-dependent changes in Ca2+ sensitivity in healthy donors, but they are reduced in DCM patients with TTN-truncating variants. A decrease in expression of Z-disk proteins may explain the observed decrease in myofibril passive stiffness and length-dependent activation.
Translational perspective
Our findings may have implications in the development of new strategies for DCM treatment in patients with TTN-truncating variants as well as in the development of new drugs.

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

Cardiovasc Res: 01 Nov 2020; epub ahead of print

Cardiac fibrosis.

Frangogiannis NG

Myocardial fibrosis, the expansion of the cardiac interstitium through deposition of extracellular matrix proteins, is a common pathophysiologic companion of many different myocardial conditions. Fibrosis may reflect activation of reparative or maladaptive processes. Activated fibroblasts and myofibroblasts are the central cellular effectors in cardiac fibrosis, serving as the main source of matrix proteins. Immune cells, vascular cells and cardiomyocytes may also acquire a fibrogenic phenotype under conditions of stress, activating fibroblast populations. Fibrogenic growth factors (such as TGF-β and PDGFs), cytokines (including TNF-α, IL-1, IL-6, IL-10 and IL-4), and neurohumoral pathways trigger fibrogenic signaling cascades through binding to surface receptors, and activation of downstream signaling cascades. In addition, matricellular macromolecules are deposited in the remodeling myocardium and regulate matrix assembly, while modulating signal transduction cascades and protease or growth factor activity. Cardiac fibroblasts can also sense mechanical stress through mechanosensitive receptors, ion channels and integrins, activating intracellular fibrogenic cascades that contribute to fibrosis in response to pressure overload. Although subpopulations of fibroblast-like cells may exert important protective actions in both reparative and interstitial/perivascular fibrosis, ultimately fibrotic changes perturb systolic and diastolic function, and may play an important role in the pathogenesis of arrhythmias. This review manuscript discusses the molecular mechanisms involved in the pathogenesis of cardiac fibrosis in various myocardial diseases, including myocardial infarction, heart failure with reduced or preserved ejection fraction (HFrEF and HFpEF), genetic cardiomyopathies and diabetic heart disease. Development of fibrosis-targeting therapies for patients with myocardial diseases will require not only understanding of the functional pluralism of cardiac fibroblasts and dissection of the molecular basis for fibrotic remodeling, but also appreciation of the pathophysiologic heterogeneity of fibrosis-associated myocardial disease.

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

Cardiovasc Res: 01 Nov 2020; epub ahead of print

STAT3-miR-17/20 signalling axis plays a critical role in attenuating myocardial infarction following rapamycin treatment in diabetic mice.

Samidurai A, Roh SK, Prakash M, Durrant D, ... Kukreja RC, Das A
Aims
Deregulation of mTOR (mammalian target of rapamycin) signalling occurs in diabetes, which exacerbates injury following myocardial infarction (MI). We therefore investigated the infarct-limiting effect of chronic treatment with rapamycin (RAPA, mTOR inhibitor) in diabetic mice following myocardial ischaemia/reperfusion (I/R) injury and delineated the potential protective mechanism.
Methods and results
Adult male diabetic (db/db) or wild-type (WT) (C57) mice were treated with RAPA (0.25 mg/kg/day, intraperitoneal) or vehicle (5% DMSO) for 28 days. The hearts from treated mice were subjected to global I/R in Langendorff mode. Cardiomyocytes, isolated from treated mice, were subjected to simulated ischaemia/reoxygenation (SI/RO) to assess necrosis and apoptosis. Myocardial infarct size was increased in diabetic heart following I/R as compared to WT. Likewise, enhanced necrosis and apoptosis were observed in isolated cardiomyocytes of diabetic mice following SI/RO. Treatment with RAPA reduced infarct size as well as cardiomyocyte necrosis and apoptosis of diabetes and WT mice. RAPA increased STAT3 phosphorylation and miRNA-17/20a expression in diabetic hearts. In addition, RAPA restored AKT phosphorylation (target of mTORC2) but suppressed S6 phosphorylation (target of mTORC1) following I/R injury. RAPA-induced cardioprotection against I/R injury as well as the induction of miR-17/20a and AKT phosphorylation were abolished in cardiac-specific STAT3-deficient diabetic mice, without alteration of S6 phosphorylation. The infarct-limiting effect of RAPA was obliterated in cardiac-specific miRNA-17-92-deficient diabetic mice. The post-I/R restoration of phosphorylation of STAT3 and AKT with RAPA were also abolished in miRNA-17-92-deficient diabetic mice. Additionally, RAPA suppressed the pro-apoptotic prolyl hydroxylase (Egln3/PHD3), a target of miRNA-17/20a in diabetic hearts, which was abrogated in miRNA-17-92-deficient diabetic mice.
Conclusion
Induction of STAT3-miRNA-17-92 signalling axis plays a critical role in attenuating MI in RAPA-treated diabetic mice. Our study indicates that chronic treatment with RAPA might be a promising pharmacological intervention for attenuating MI and improving prognosis in diabetic patients.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: [email protected]

Cardiovasc Res: 31 Oct 2020; 116:2103-2115

Melatonin inhibits inflammasome-associated activation of endothelium and macrophages attenuating pulmonary arterial hypertension.

Zhang J, Lu X, Liu M, Fan H, ... Kretowski A, Li X
Aims
Pulmonary arterial hypertension (PAH) is a pathophysiological syndrome associated with pulmonary/systemic inflammation. Melatonin relieves PAH, but the molecular mode of action remains unclear. Here, we investigated the role of melatonin in normalizing vascular homeostasis.
Methods and results
Light-time mean serum melatonin concentration was lower in patients with PAH than in normal controls [11.06 ± 3.44 (7.13-15.6) vs. 14.55 ± 1.28 (8.0-19.4) pg/mL], which was negatively correlated with increased serum levels of interleukin-1β (IL-1β) in patients with PAH. We showed that inflammasomes were activated in the PAH mice model and that melatonin attenuated IL-1β secretion. On one hand, melatonin reduced the number of macrophages in lung by inhibiting the endothelial chemokines and adhesion factors. Moreover, use of Il1r-/- mice, Caspase1/11-/- mice, and melatonin-treated mice revealed that melatonin reduced hypoxia-induced vascular endothelial leakage in the lung. On the other hand, we verified that melatonin reduced the formation of inflammasome multiprotein complexes by modulating calcium ions in macrophages using a live cell station, and melatonin decreased inositol triphosphate and increased cAMP. Furthermore, knockdown of melatonin membrane receptors blocked melatonin function, and a melatonin membrane receptors agonist inactivated inflammasomes in macrophages.
Conclusion
Melatonin attenuated inflammasome-associated vascular disorders by directly improving endothelial leakage and decreasing the formation of inflammasome multiprotein complexes in macrophages. Taken together, our data provide a theoretical basis for applying melatonin clinically, and inflammasomes may be a possible target of PAH treatment.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: [email protected]

Cardiovasc Res: 31 Oct 2020; 116:2156-2169

GHSR deficiency exacerbates cardiac fibrosis: role in macrophage inflammasome activation and myofibroblast differentiation.

Wang M, Qian L, Li J, Ming H, ... Liu Y, Wang N
Aims
Sustained activation of β-adrenergic signalling induces cardiac fibrosis, which marks progression to heart failure. GHSR (growth hormone secretagogue receptor) is the receptor for ghrelin, which is an orexigenic gastric hormone with newly defined cardiovascular effects. The present study determined the effects of GHSR deficiency in a mouse model of isoproterenol (ISO)-induced cardiac fibrosis and examined the underlying mechanism.
Methods and results
Histochemical studies showed that GHSR deficiency exacerbated cardiac fibrosis. Quantitative RT-PCR, western blotting, and immunofluorescence staining demonstrated that cardiac fibroblasts isolated from GHSR-/- mice exhibited increased expression of marker genes for myofibroblast trans-differentiation (α-SMA, SM22, and calponin) upon transforming growth factor-β treatment compared to wild-type mice. RNA-sequencing of heart transcriptomes revealed that differentially expressed genes in GHSR-/- hearts were enriched in such biological processes as extracellular matrix organization, inflammatory response, lipid metabolism, cell cycle, migration, and adhesion. Particularly, GHSR deficiency increased Wnt/β-catenin pathway activation in ISO-induced myocardial fibrosis. In addition, loss of GHSR in macrophages instigated inflammasome activation with increased cleavage and release of interleukin-18.
Conclusion
These results for the first time demonstrated that GHSR deficiency aggravated ISO-induced cardiac fibrosis, suggesting that GHSR was a potential target for the intervention of cardiac fibrosis.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: [email protected]

Cardiovasc Res: 31 Oct 2020; 116:2091-2102

Decreased Jagged1 expression in vascular smooth muscle cells delays endothelial regeneration in arteriovenous graft.

Guo Q, Huang F, Qing Y, Feng S, ... Mitch WE, Cheng J
Aims
It is well-established that endothelial dysfunction promotes activation of vascular smooth muscle cell (VSMC). Whether decreased accumulation of VSMCs affects endothelial regeneration and functions in arteriovenous graft (AVG) remodelling has not been studied. We sought to identify mechanisms by which the Notch ligand, Jagged1, in VSMCs regulates endothelial cell (EC) functions in AVGs.
Methods and results
AVGs were created in transgenic mice bearing VSMC-specific knockout (KO) or overexpression of Jagged1. VSMC migration, EC regeneration, and its barrier functions as well as AVG remodelling were evaluated. Jagged1 expression was induced in VSMCs of neointima in the AVGs. Jagged1 KO in VSMCs inhibited the accumulation of extracellular matrix as well as VSMC migration. Fewer α-SMA-positive VSMCs were found in AVGs created in VSMC-specific Jagged1 KO mice (VSMCJagged1 KO mice) vs. in WT mice. Decreased VSMCs in AVGs were associated with deterioration of EC functions. In AVGs created in transgenic mice bearing Jagged1 KO in VSMCs exhibited delayed EC regeneration and impaired EC barrier function. Barrier dysfunction of ECs increased inflammatory cell infiltration and dysregulation of AVG remodelling and arterialization. The increased expression of IL-1β in macrophages was associated with expression of adhesion markers in ECs in AVGs created in VSMCJagged1 KO mice. In contrast, AVGs created in mice with overexpression of Jagged1 in VSMCs exhibited improved EC regeneration plus decreased macrophage infiltration. This led to AVG remodelling and arterialization. In co-cultures of ECs and VSMCs, Jagged1 deficiency in VSMCs suppressed N-cadherin and integrin β3 expression in ECs. Inhibition of integrin β3 activation delayed EC spreading and migration. Notably, Jagged1 overexpression in VSMCs or treatment with recombinant Jagged1 stimulated the expression of N-cadherin and integrin β3 in ECs. Jagged1-induced responses were blocked by inhibition of Notch signalling.
Conclusions
Jagged1 expression in VSMCs maintains EC barrier functions and blocks infiltration of macrophages. These responses promote remodelling and arterialization of AVGs.

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

Cardiovasc Res: 31 Oct 2020; 116:2142-2155

Impact of functional studies on exome sequence variant interpretation in early-onset cardiac conduction system diseases.

Hayashi K, Teramoto R, Nomura A, Asano Y, ... Kawashiri MA, Takamura M
Aims
The genetic cause of cardiac conduction system disease (CCSD) has not been fully elucidated. Whole-exome sequencing (WES) can detect various genetic variants; however, the identification of pathogenic variants remains a challenge. We aimed to identify pathogenic or likely pathogenic variants in CCSD patients by using WES and 2015 American College of Medical Genetics and Genomics (ACMG) standards and guidelines as well as evaluating the usefulness of functional studies for determining them.
Methods and results
We performed WES of 23 probands diagnosed with early-onset (<65 years) CCSD and analysed 117 genes linked to arrhythmogenic diseases or cardiomyopathies. We focused on rare variants (minor allele frequency < 0.1%) that were absent from population databases. Five probands had protein truncating variants in EMD and LMNA which were classified as \'pathogenic\' by 2015 ACMG standards and guidelines. To evaluate the functional changes brought about by these variants, we generated a knock-out zebrafish with CRISPR-mediated insertions or deletions of the EMD or LMNA homologs in zebrafish. The mean heart rate and conduction velocities in the CRISPR/Cas9-injected embryos and F2 generation embryos with homozygous deletions were significantly decreased. Twenty-one variants of uncertain significance were identified in 11 probands. Cellular electrophysiological study and in vivo zebrafish cardiac assay showed that two variants in KCNH2 and SCN5A, four variants in SCN10A, and one variant in MYH6 damaged each gene, which resulted in the change of the clinical significance of them from \'Uncertain significance\' to \'Likely pathogenic\' in six probands.
Conclusion
Of 23 CCSD probands, we successfully identified pathogenic or likely pathogenic variants in 11 probands (48%). Functional analyses of a cellular electrophysiological study and in vivo zebrafish cardiac assay might be useful for determining the pathogenicity of rare variants in patients with CCSD. SCN10A may be one of the major genes responsible for CCSD.

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

Cardiovasc Res: 31 Oct 2020; 116:2116-2130

Moderate but not severe hypothermia causes pro-arrhythmic changes in cardiac electrophysiology.

Dietrichs ES, McGlynn K, Allan A, Connolly A, ... Tveita T, Smith GL
Aims
Treatment of arrhythmias evoked by hypothermia/rewarming remains challenging, and the underlying mechanisms are unclear. This in vitro experimental study assessed cardiac electrophysiology in isolated rabbit hearts at temperatures occurring in therapeutic and accidental hypothermia.
Methods and results
Detailed ECG, surface electrogram, and panoramic optical mapping were performed in isolated rabbit hearts cooled to moderate (31°C) and severe (17°C) hypothermia. Ventricular activation was unchanged at 31°C while action potential duration (APD) was significantly prolonged (176.9 ± 4.2 ms vs. 241.0 ± 2.9 ms, P < 0.05), as was ventricular repolarization. At 17°C, there were proportionally similar delays in both activation and repolarization. These changes were reflected in the QRS and QT intervals of ECG recordings. Ventricular fibrillation threshold was significantly reduced at 31°C (16.3 ± 3.1 vs. 35 ± 3.5 mA, P < 0.05) but increased at 17°C (64.2 ± 9.9, P < 0.05). At 31°C, transverse conduction was relatively unchanged by cooling compared to longitudinal conduction, but at 17°C both transverse and longitudinal conduction were proportionately reduced to a similar extent. The gap junction uncoupler heptanol had a larger relative effect on transverse than longitudinal conduction and was able to restore the transverse/longitudinal conduction ratio, returning ventricular fibrillation threshold to baseline values (16.3 ± 3.1 vs. 36.3 ± 4.3 mA, P < 0.05) at 31°C. Rewarming to 37°C restored the majority of the electrophysiological parameters.
Conclusions
Moderate hypothermia does not significantly change ventricular conduction time but prolongs repolarization and is pro-arrhythmic. Further cooling to severe hypothermia causes parallel changes in ventricular activation and repolarization, changes which are anti-arrhythmic. Therefore, relative changes in QRS and QT intervals (QR/QTc) emerge as an ECG-biomarker of pro-arrhythmic activity. Risk for ventricular fibrillation appears to be linked to the relatively low temperature sensitivity of ventricular transmural conduction, a conclusion supported by the anti-arrhythmic effect of heptanol at 31°C.

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

Cardiovasc Res: 31 Oct 2020; 116:2081-2090

Compartmentalized β1-adrenergic signalling synchronizes excitation-contraction coupling without modulating individual Ca2+ sparks in healthy and hypertrophied cardiomyocytes.

Yang HQ, Zhou P, Wang LP, Zhao YT, ... Xu M, Wang SQ
Aims
β-adrenergic receptors (βARs) play pivotal roles in regulating cardiac excitation-contraction (E-C) coupling. Global signalling of β1ARs up-regulates both the influx of Ca2+ through sarcolemmal L-type Ca2+ channels (LCCs) and the release of Ca2+ from the sarcoplasmic reticulum (SR) through the ryanodine receptors (RyRs). However, we recently found that β2AR stimulation meditates \'offside compartmentalization\', confining β1AR signalling into subsarcolemmal nanodomains without reaching SR proteins. In the present study, we aim to investigate the new question, whether and how compartmentalized β1AR signalling regulates cardiac E-C coupling.
Methods and results
By combining confocal Ca2+ imaging and patch-clamp techniques, we investigated the effects of compartmentalized βAR signalling on E-C coupling at both cellular and molecular levels. We found that simultaneous activation of β2 and β1ARs, in contrast to global signalling of β1ARs, modulated neither the amplitude and spatiotemporal properties of Ca2+ sparks nor the kinetics of the RyR response to LCC Ca2+ sparklets. Nevertheless, by up-regulating LCC current, compartmentalized β1AR signalling synchronized RyR Ca2+ release and increased the functional reserve (stability margin) of E-C coupling. In circumstances of briefer excitation durations or lower RyR responsivity, compartmentalized βAR signalling, by increasing the intensity of Ca2+ triggers, helped stabilize the performance of E-C coupling and enhanced the Ca2+ transient amplitude in failing heart cells.
Conclusion
Given that compartmentalized βAR signalling can be induced by stress-associated levels of catecholamines, our results revealed an important, yet unappreciated, heart regulation mechanism that is autoadaptive to varied stress conditions.

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

Cardiovasc Res: 31 Oct 2020; 116:2069-2080

The impact of patient sex on the response to intramyocardial mesenchymal stem cell administration in patients with non-ischaemic dilated cardiomyopathy.

Florea V, Rieger AC, Natsumeda M, Tompkins BA, ... Mitrani RD, Hare JM
Aims
Sex differences impact the occurrence, presentation, prognosis, and response to therapy in heart disease. Particularly, the phenotypic presentation of patients with non-ischaemic dilated cardiomyopathy (NIDCM) differs between men and women. However, whether the response to mesenchymal stem cell (MSC) therapy is influenced by sex remains unknown. We hypothesize that males and females with NIDCM respond similarly to MSC therapy.
Methods and results
Male (n = 24) and female (n = 10) patients from the POSEIDON-DCM trial who received MSCs via transendocardial injections were evaluated over 12 months. Endothelial function was measured at baseline and 3 months post-transendocardial stem cell injection (TESI). At baseline, ejection fraction (EF) was lower (P = 0.004) and end-diastolic volume (EDV; P = 0.0002) and end-systolic volume (ESV; P = 0.0002) were higher in males vs. females. In contrast, baseline demographic characteristics, Minnesota Living with Heart Failure Questionnaire (MLHFQ), and 6-min walk test (6MWT) were similar between groups. EF improved in males by 6.2 units (P = 0.04) and in females by 8.6 units (P = 0.04; males vs. females, P = 0.57). EDV and ESV were unchanged over time. The MLHFQ score, New York Heart Association (NYHA) class, endothelial progenitor cell-colony forming units, and serum tumour necrosis factor alpha improved similarly in both groups.
Conclusion
Despite major differences in phenotypic presentation of NIDCM in males and females, this study is the first of its kind to demonstrate that MSC therapy improves a variety of parameters in NIDCM irrespective of patient sex. These findings have important clinical and pathophysiologic implications regarding the impact of sex on responses to cell-based therapy for NIDCM.

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

Cardiovasc Res: 31 Oct 2020; 116:2131-2141

The choice of targets and ligands for site-specific delivery of nanomedicine to atherosclerosis.

Zia A, Wu Y, Nguyen T, Wang X, Peter K, Ta HT

As nanotechnologies advance into clinical medicine, novel methods for applying nanomedicine to cardiovascular diseases are emerging. Extensive research has been undertaken to unlock the complex pathogenesis of atherosclerosis. However, this complexity presents challenges to develop effective imaging and therapeutic modalities for early diagnosis and acute intervention. The choice of ligand-receptor system vastly influences the effectiveness of nanomedicine. This review collates current ligand-receptor systems used in targeting functionalized nanoparticles for diagnosis and treatment of atherosclerosis. Our focus is on the binding affinity and selectivity of ligand-receptor systems, as well as the relative abundance of targets throughout the development and progression of atherosclerosis. Antibody-based targeting systems are currently the most commonly researched due to their high binding affinities when compared with other ligands, such as antibody fragments, peptides, and other small molecules. However, antibodies tend to be immunogenic due to their size. Engineering antibody fragments can address this issue but will compromise their binding affinity. Peptides are promising ligands due to their synthetic flexibility and low production costs. Alongside the aforementioned binding affinity of ligands, the choice of target and its abundance throughout distinct stages of atherosclerosis and thrombosis is relevant to the intended purpose of the nanomedicine. Further studies to investigate the components of atherosclerotic plaques are required as their cellular and molecular profile shifts over time.

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

Cardiovasc Res: 31 Oct 2020; 116:2055-2068

Artificial intelligence in medical imaging: A radiomic guide to precision phenotyping of cardiovascular disease.

Oikonomou EK, Siddique M, Antoniades C
Abstract
Rapid technological advances in non-invasive imaging, coupled with the availability of large data sets and the expansion of computational models and power, have revolutionized the role of imaging in medicine. Non-invasive imaging is the pillar of modern cardiovascular diagnostics, with modalities such as cardiac computed tomography (CT) now recognized as first-line options for cardiovascular risk stratification and the assessment of stable or even unstable patients. To date, cardiovascular imaging has lagged behind other fields, such as oncology, in the clinical translational of artificial intelligence (AI)-based approaches. We hereby review the current status of AI in non-invasive cardiovascular imaging, using cardiac CT as a running example of how novel machine learning (ML)-based radiomic approaches can improve clinical care. The integration of ML, deep learning, and radiomic methods has revealed direct links between tissue imaging phenotyping and tissue biology, with important clinical implications. More specifically, we discuss the current evidence, strengths, limitations, and future directions for AI in cardiac imaging and CT, as well as lessons that can be learned from other areas. Finally, we propose a scientific framework in order to ensure the clinical and scientific validity of future studies in this novel, yet highly promising field. Still in its infancy, AI-based cardiovascular imaging has a lot to offer to both the patients and their doctors as it catalyzes the transition towards a more precise phenotyping of cardiovascular disease.

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

Cardiovasc Res: 31 Oct 2020; 116:2040-2054

Selectin-Targeting Glycosaminoglycan-Peptide Conjugate Limits Neutrophil Mediated Cardiac Reperfusion Injury.

Dehghani T, Thai PN, Sodhi H, Ren L, ... Chiamvimonvat N, Panitch A
Aims
One of the hallmarks of myocardial infarction (MI) is excessive inflammation. During an inflammatory insult, damaged endothelial cells shed their glycocalyx, a carbohydrate-rich layer on the cell surface which provides a regulatory interface to immune cell adhesion. Selectin-mediated neutrophilia occurs as a result of endothelial injury and inflammation. We recently designed a novel selectin-targeting glycocalyx mimetic (termed DS-IkL) capable of binding inflamed endothelial cells. This study examines the capacity of DS-IkL to limit neutrophil binding and platelet activation on inflamed endothelial cells, as well as the cardio-protective effects of DS-IkL after acute myocardial infarction.
Methods and results
In vitro, DS-IkL diminished neutrophil interactions with both recombinant selectin and inflamed endothelial cells, and limited platelet activation on inflamed endothelial cells. Our data demonstrated that DS-IkL localized to regions of vascular inflammation in vivo after 45 minutes of left anterior descending coronary artery ligation induced MI. Further, findings from this study show DS-IkL treatment had short- and long-term cardioprotective effects after ischemia/reperfusion at the left anterior descending coronary artery. Mice treated with DS-IkL immediately after ischemia/reperfusion and 24 hours later exhibited reduced neutrophil extravasation, macrophage accumulation, fibroblast and endothelial cell proliferation, and fibrosis compared to saline controls.
Conclusions
Our findings suggest that DS-IkL has great therapeutic potential after MI by limiting reperfusion injury induced by the immune response.
Translational perspective
Cardiovascular disease remains the leading cause of mortality worldwide. Acute inflammation from myocardial infarction (MI) results in damaged endothelial cells, leading to the loss of glycocalyx. Here, we designed a novel selectin-targeting glycocalyx mimetic (termed DS-IkL) capable of binding inflamed endothelial cells. DS-IkL limits neutrophil binding and platelet activation on inflamed endothelial cells. Treatment with DS-IkL in a preclinical model of MI reduces infarct size by preventing neutrophil extravasation, macrophage accumulation, fibroblast and endothelial cell proliferation, and fibrosis. Our findings suggest that DS-IkL has great therapeutic potential after MI by limiting reperfusion injury induced by the immune response.

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

Cardiovasc Res: 29 Oct 2020; epub ahead of print

Genetic Deletion of p66shc and/or Cyclophilin D Results in Decreased Pulmonary Vascular Tone.

Gierhardt M, Pak O, Sydykov A, Kraut S, ... Heger J, Sommer N
Aims
The pulmonary vascular tone and hypoxia-induced alterations of the pulmonary vasculature may be regulated by the mitochondrial membrane permeability transition pore (mPTP) that controls mitochondrial calcium load and apoptosis. We thus investigated, if the mitochondrial proteins p66shc and cyclophilin D (CypD) that regulate mPTP opening affect the pulmonary vascular tone.
Methods and results
Mice deficient for p66shc (p66shc-/-), CypD (CypD-/-), or both proteins (p66shc/CypD-/-) exhibited decreased pulmonary vascular resistance (PVR) compared to wild-type mice determined in isolated lungs and in vivo. In contrast, systemic arterial pressure was only lower in CypD-/- mice. As cardiac function and pulmonary vascular remodelling did not differ between genotypes, we determined alterations of vascular contractility in isolated lungs and calcium handling in pulmonary arterial smooth muscle cells (PASMC) as underlying reason for decreased PVR. Potassium chloride (KCl)-induced pulmonary vasoconstriction and KCl-induced cytosolic calcium increase determined by Fura-2 were attenuated in all gene-deficient mice. In contrast, KCl-induced mitochondrial calcium increase determined by the genetically encoded Mito-Car-GECO and calcium retention capacity were increased only in CypD-/- and p66shc/CypD-/- mitochondria indicating that decreased mPTP opening affected KCl-induced intracellular calcium peaks in these cells. All mouse strains showed a similar pulmonary vascular response to chronic hypoxia, while acute hypoxic pulmonary vasoconstriction was decreased in gene-deficient mice indicating that CypD and p66shc regulates vascular contractility but not remodelling.
Conclusions
We conclude that p66shc specifically regulates the pulmonary vascular tone, while CypD also affects systemic pressure. However, only CypD acts via regulation of mPTP opening and mitochondrial calcium regulation.
Translational perspective
Pulmonary hypertension is a progressive disease of the pulmonary vasculature ultimately resulting in right heart failure. Thus, therapeutic options targeting specifically the pulmonary vasculature are urgently needed.Our study describes for the first time the role of the proteins p66shc and CypD in the regulation of the pulmonary vascular tone. As the effect of p66shc-/- was specific for the pulmonary vasculature, it is an interesting target for future research on therapies for pulmonary vascular diseases like pulmonary hypertension.

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

Cardiovasc Res: 28 Oct 2020; epub ahead of print

Transcriptome and proteome mapping in the sheep atria reveal molecular features of atrial fibrillation progression.

Alvarez-Franco A, Rouco R, Ramirez RJ, Guerrero-Serna G, ... Jalife J, Manzanares M
Aims
Atrial fibrillation (AF) is a progressive cardiac arrhythmia that increases the risk of hospitalization and adverse cardiovascular events. There is a clear demand for more inclusive and large-scale approaches to understand the molecular drivers responsible for AF, as well as the fundamental mechanisms governing the transition from paroxysmal to persistent and permanent forms. In this study, we aimed to create a molecular map of AF and find the distinct molecular programs underlying cell type-specific atrial remodelling and AF progression.
Methods and results
We used a sheep model of long-standing, tachypacing-induced AF, sampled right and left atrial tissue and isolated cardiomyocytes from control, intermediate (transition) and late time points during AF progression, and performed transcriptomic and proteome profiling. We have merged all these layers of information into a meaningful 3-component space in which we explored the genes and proteins detected and their common patterns of expression. Our data-driven analysis points at extracellular matrix remodelling, inflammation, ion channel, myofibril structure, mitochondrial complexes, chromatin remodelling, and genes related to neural function, as well as critical regulators of cell proliferation as hallmarks of AF progression. Most important, we prove that these changes occur at early transitional stages of the disease, but not at later stages, and that the left atrium undergoes significantly more profound changes than the right atrium in its expression program. The pattern of dynamic changes in gene and protein expression replicate the electrical and structural remodelling demonstrated previously in the sheep and in humans, and uncover novel mechanisms potentially relevant for disease treatment.
Conclusions
Transcriptomic and proteomic analysis of AF progression in a large animal model shows that significant changes occur at early stages, and that among others involve previously undescribed increase in mitochondria, changes to the chromatin of atrial cardiomyocytes, and genes related to neural function and cell proliferation.
Translational perspective
We have generated a detailed molecular map of AF progression in a clinically relevant large-animal model. Such data would be very difficult if not impossible to obtain from patients. Our results provide a framework for a comprehensive molecular analysis of the disease, pointing to novel avenues of research toward identifying early events that can lead to therapeutically targets to prevent AF-induced atrial remodelling.

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

Cardiovasc Res: 28 Oct 2020; epub ahead of print

Caloric restriction mimetics for the treatment of cardiovascular diseases.

Sciarretta S, Forte M, Castoldi F, Frati G, ... Kroemer G, Maiuri MC

Caloric restriction mimetics (CRMs) are emerging as potential therapeutic agents for the treatment of cardiovascular diseases. CRMs include natural and synthetic compounds able to inhibit protein acetyltransferases, to interfere with acetyl coenzyme A biosynthesis or to activate (de)acetyltransferase proteins. These modifications mimic the effects of caloric restriction, which is associated with the activation of autophagy. Previous evidence demonstrated the ability of CRMs to ameliorate cardiac function and reduce cardiac hypertrophy and maladaptive remodeling in animal models of aging, mechanical overload, chronic myocardial ischemia, as well as in genetic and metabolic cardiomyopathies. In addition, CRMs were found to reduce acute ischemia-reperfusion injury. In many cases, these beneficial effects of CRMs appeared to be mediated by autophagy activation. In the present review, we discuss the relevant literature about the role of different CRMs in animal models of cardiac diseases, emphasizing the molecular mechanisms underlying the beneficial effects of these compounds and their potential future clinical application.

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

Cardiovasc Res: 23 Oct 2020; epub ahead of print

Atrial nitroso-redox balance and refractoriness following on-pump cardiac surgery: A randomised trial of atorvastatin.

Jayaram R, Jones M, Reilly S, Crabtree MJ, ... Hill M, Casadei B
Aims
Systemic inflammation and increased activity of atrial NOX2-containing NADPH oxidases have been associated with the new onset of atrial fibrillation (AF) after cardiac surgery. In addition to lowering LDL-cholesterol, statins exert rapid anti-inflammatory and antioxidant effects, the clinical significance of which remains controversial.
Methods and results
We first assessed the impact of cardiac surgery and cardiopulmonary bypass (CPB) on atrial nitroso-redox balance by measuring NO synthase (NOS) and GTP Cyclohydrolase -1 (GCH-1) activity, biopterin content, and superoxide production in paired samples of the right atrial appendage obtained before (PRE) and after CPB and reperfusion (POST) in 116 patients. The effect of perioperative treatment with atorvastatin (80 mg once daily) on these parameters, blood biomarkers and the postoperative atrial effective refractory period (AERP) was then evaluated in a randomized, double-blind, placebo-controlled study in 80 patients undergoing cardiac surgery on CPB.CPB and reperfusion led to a significant increase in atrial superoxide production (74% CI, 71-76%, n = 46 paired samples, P < 0.0001) and a reduction in atrial tetrahydrobiopterin (BH4) (34% CI, 33-35%, n = 36 paired samples, P < 0.01), and in GCH-1 (56% CI, 55-58%, n = 26 paired samples, P < 0.001) and NOS activity (58% CI, 52-67%, n = 20 paired samples, P < 0.001). Perioperative atorvastatin treatment prevented the effect of CPB and reperfusion on all parameters but had no significant effect on the postoperative right AERP, troponin release, or NT-pro BNP after cardiac surgery.
Conclusions
Perioperative statin therapy prevents post-reperfusion atrial nitroso-redox imbalance in patients undergoing on-pump cardiac surgery but has no significant impact on postoperative atrial refractoriness, perioperative myocardial injury, or markers of postoperative LV function.Clinical
Trial registration:
information: https://clinicaltrials.gov/ct2/show/NCT01780740.
Translational perspective
Increased atrial ROS production is associated with both incident and prevalent AF, with experimental findings suggesting it may have a causal role in AF induction and AF-induced electrical remodelling. Statin therapy causes a reduction in myocardial and vascular ROS production and as such it may prevent the new onset of AF after cardiac surgery. In patients undergoing on-pump cardiac surgery, we show that perioperative administration of statins prevents myocardial nitroso-redox imbalance after reperfusion without affecting atrial refractoriness or perioperative myocardial injury. These findings suggest that targeting myocardial nitroso-redox imbalance would be unlikely to prevent postoperative complications in patients undergoing on-pump cardiac surgery.

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

Cardiovasc Res: 23 Oct 2020; epub ahead of print

Double Trouble: Combined Cardiovascular Effects of Particulate Matter Exposure and COVID-19.

Tanwar V, Adelstein JM, Wold LE

The coronavirus disease-2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly grown into a pandemic. According to initial reports, the lungs were thought to be the primary target, but recent case studies have shown its reach can extend to other organs including the heart and blood vessels. The severity of cardiac complications of COVID-19 depends on multiple underlying factors, with air pollutant exposure being one of them as reported by several recent studies. Airborne particulate matter attracts heightened attention due to its implication in various diseases, especially respiratory and cardiovascular diseases. Inhaled particulate matter not only carries microorganisms inside the body but also elicits local and systemic inflammatory responses resulting in altering host\'s immunity and increasing susceptibility to infection. Previous as well as recent studies have documented that particulate matter acts as a \"carrier\" for the virus and aids in spreading viral infections. This review presents the mechanisms and effects of viral entry and how pollution can potentially modulate pathophysiological processes in the heart. We aimed to concisely summarize studies examining cardiovascular (CV) outcomes in COVID-19 patients and postulate on how particulate matter can influence these outcomes. We have also reviewed evidence on the use of rennin-angiotensin system (RAS) inhibitors, namely, ACE inhibitors and angiotensin receptor blockers, in patients with COVID-19. The interplay of pollution and SARS-CoV-2 is essential to understanding the effects of accentuated cardiovascular effects of COVID-19 and deserves in depth experimental investigations.

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

Cardiovasc Res: 20 Oct 2020; epub ahead of print

Omega-3 fatty acids improve flow-induced vasodilation by enhancing TRPV4 in arteries from diet-induced obese mice.

Zhu Y, Wen L, Wang S, Zhang K, ... Wang R, Ma X
Aims
Previous studies have shown the intake of omega-3 polyunsaturated fatty acids are associated with low rates of obesity and ischemic pathologies. Omega-3 also have anti-inflammatory and plaque-stabilization effects and regulate vasodilation and constriction. However, there are few studies of the role of omega-3 in flow-induced vasodilation involving Ca2+-permeable ion channel TRPV4 in high-fat diet-induced obese (DIO) mouse. Here, we determined whether omega-3 protect against vascular dysfunction induced by high-fat diet by enhancing TRPV4 activity and subsequently improving flow-mediated vasodilation.
Methods and results
Flow-mediated vasodilation in 2nd-order mesenteric arteries from mice was measured using a pressure myograph. The intracellular Ca2+ concentration in response to flow and GSK1016790A (a TRPV4 agonist) was measured by Fluo-4 fluorescence. Whole-cell current was measured by patch clamp. Cell membrane tether force was measured by atomic force microscopy. Impairment of flow-mediated vasodilation in arteries and Ca2+ influx in endothelial cells from DIO mice was restored by omega-3 treatment. The improved flow-induced vasodilation was inhibited by the TRPV4 antagonist HC067047 and in TRPV4-/- mice. Omega-3 treatment enhanced endothelial TRPV4 activity and altered cell membrane mechanic property, as indicated by enhanced GSK1016790A-induced Ca2+ influx and whole-cell current and altered membrane mean tether force in endothelial cells from DIO mice.
Conclusion
Omega-3 improve vascular function by improving flow-induced vasodilation via enhancing TRPV4 activity in the endothelium of obese mice which may be related to improved cell membrane physical property. Activation of TRPV4 in endothelium plays an important role in the protective mechanisms of omega-3 against vascular dysfunction in obesity by improving flow-mediated vasodilation.
Translational perspective
Omega-3 improve the endothelial function via enhancing TRPV4 activity and augmenting the endothelial-dependent flow-induced vasodilation in DIO mice resistance arteries. This study provides a strategy of improving vascular function under obesity, namely, by targeting TRPV4 via the usage of omega-3.

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

Cardiovasc Res: 17 Oct 2020; epub ahead of print

Haplo-insufficiency of Tmem43 in cardiac myocytes activates the DNA damage response pathway leading to a Late-Onset Senescence-Associated pro-fibrotic cardiomyopathy.

Rouhi L, Cheedipudi SM, Chen SN, Fan S, ... Gurha P, Marian AJ
Aims
Arrhythmogenic cardiomyopathy (ACM) encompasses a genetically heterogeneous group of myocardial diseases whose manifestations are sudden cardiac death, cardiac arrhythmias, heart failure, and in a subset fibro-adipogenic infiltration of the myocardium. Mutations in the TMEM43 gene, encoding transmembrane protein 43 (TMEM43) are known to cause ACM. The purpose of the study was to gain insights into the molecular pathogenesis of ACM caused by TMEM43 haploinsufficiency.
Methods and results
The Tmem43 gene was specifically deleted in cardiac myocytes by crossing the Myh6-Cre and floxed Tmem43 mice. Myh6-Cre: Tmem43W/F mice showed an age-dependent phenotype characterized by an increased mortality, cardiac dilatation and dysfunction, myocardial fibrosis, adipogenesis, and apoptosis. Sequencing of cardiac myocyte transcripts prior to and after the onset of cardiac phenotype predicted early activation of the TP53 pathway. Increased TP53 activity was associated with increased levels of markers of DNA damage response (DDR), and a subset of senescence-associated secretary phenotype (SASP). Activation of DDR, TP53, SASP and their selected downstream effectors, including phospho-SMAD2 and phospho-SMAD3 were validated by alternative methods, including immunoblotting. Expression of SASP was associated with epithelial-mesenchymal transition (EMT) and age-dependent expression of myocardial fibrosis and apoptosis in the Myh6-Cre: Tmem43W/F mice.
Conclusions
TMEM43 haplo-insufficiency is associated with activation of the DDR and the TP53 pathways, which lead to increased expression of SASP and an age-dependent expression of a pro-fibrotic cardiomyopathy. Given that TMEM43 is a nuclear envelope protein and our previous data showing deficiency of another nuclear envelope protein, namely lamin A/C, activates the DDR/TP53 pathway, we surmise that DNA damage is a shared mechanism in the pathogenesis of cardiomyopathies caused by mutations involving nuclear envelope proteins.
Translational perspective
The data indicate that the DNA damage response (DDR) to double stranded DNA breaks (DSBs) is activated in a mouse model of cardiomyopathy caused by haplo-insufficiency of the Tmem43 gene. The TMEM43 gene is a known cause of arrhythmogenic cardiomyopathy in humans. The DDR activates the TP53 pathway and leads to expression of senescence associated secretary phenotype (SASP), such as TGFβ1, which induce a senescence-associated pro-fibrotic cardiomyopathy.These findings along with our previous data identify the DDR as a putative common mechanism in the pathogenesis of cardiomyopathies, and likely in the pathogenesis of over two dozen diseases, caused by mutations in the nuclear envelope proteins (envelopathies).

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

Cardiovasc Res: 17 Oct 2020; epub ahead of print

TNAP as a therapeutic target for cardiovascular calcification - a discussion of its pleiotropic functions in the body.

Claudia G, Agnieszka SK, Laurence B, Thibaut Q, ... Caroline F, David M

Cardiovascular calcification (CVC) is associated with increased morbidity and mortality. It develops in several diseases and locations, such as in the tunica intima in atherosclerosis plaques, in the tunica media in type 2 diabetes and chronic kidney disease, and in aortic valves. In spite of the wide occurrence of CVC and its detrimental effects on cardiovascular diseases (CVD), no treatment is yet available. Most of CVC involve mechanisms similar to those occurring during endochondral and/or intramembranous ossification. Logically, since tissue-nonspecific alkaline phosphatase (TNAP) is the key-enzyme responsible for skeletal/dental mineralization, it is a promising target to limit CVC. Tools have recently been developed to inhibit its activity and preclinical studies conducted in animal models of vascular calcification already provided promising results. Nevertheless, as its name indicates, TNAP is ubiquitous and recent data indicate that it dephosphorylates different substrates in vivo to participate in other important physiological functions besides mineralization. For instance, TNAP is involved in the metabolism of pyridoxal phosphate and the production of neurotransmitters. TNAP has also been described as an anti-inflammatory enzyme able to dephosphorylate adenosine nucleotides and lipopolysaccharide. A better understanding of the full spectrum of TNAP\'s functions is needed to better characterize the effects of TNAP inhibition in diseases associated with CVC. In this review, after a brief description of the different types of CVC, we describe the newly uncovered additional functions of TNAP and discuss the expected consequences of its systemic inhibition in vivo.

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

Cardiovasc Res: 17 Oct 2020; epub ahead of print

Dietary Carbohydrates Restriction Inhibits The Development Of Cardiac Hypertrophy And Heart Failure.

Nakamura M, Odanovic N, Nakada Y, Dohi S, ... Abdellatif M, Sadoshima J
Aims
A diet with modified components, such as a ketogenic low-carbohydrate (LC) diet, potentially extends longevity and healthspan. However, how a LC diet impacts on cardiac pathology during hemodynamic stress remains elusive. This study evaluated the effects of a LC diet high in either fat (Fat-LC) or protein (Pro-LC) in a mouse model of chronic hypertensive cardiac remodeling.
Methods and results
Wild-type mice were subjected to transverse aortic constriction, followed by feeding with the Fat-LC, the Pro-LC, or a high-carbohydrate control diet. After 4 weeks, echocardiographic, hemodynamic, histological and biochemical analyses were performed. LC diet consumption after pressure overload inhibited the development of pathological hypertrophy and systolic dysfunction compared to the control diet. An anti-hypertrophic serine/threonine kinase, GSK-3β, was re-activated by both LC diets; however, the Fat-LC, but not the Pro-LC, diet exerted cardioprotection in GSK-3β cardiac-specific knockout mice. β-hydroxybutyrate, a major ketone body in mammals, was increased in the hearts of mice fed the Fat-LC, but not the Pro-LC, diet. In cardiomyocytes, ketone body supplementation inhibited phenylephrine-induced hypertrophy, in part by suppressing mTOR signaling.
Conclusions
Strict carbohydrate restriction suppresses pathological cardiac growth and heart failure after pressure overload through distinct anti-hypertrophic mechanisms elicited by supplemented macronutrients.
Translational perspective
Hemodynamic stress, such as hypertension, induces pathological cardiac hypertrophy, leading to heart failure. There is growing evidence that modulating components of diet affects cardiac function in humans, although the causality and underlying mechanisms are poorly understood. Our study demonstrates that strict restriction of dietary carbohydrates supplemented with either fat or proteins during acute hemodynamic stress attenuates the development and progression of cardiac hypertrophy and heart failure by activating distinct anti-hypertrophic and cardioprotective signaling mechanisms. The study suggests that it would be useful to investigate the therapeutic benefit of carbohydrate restriction in patients with hypertension and cardiac hypertrophy in clinical studies.

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

Cardiovasc Res: 17 Oct 2020; epub ahead of print

The physiological and pathological functions of VEGFR3 in cardiac and lymphatic development and related diseases.

Monaghan RM, Page DJ, Ostergaard P, Keavney BD

Vascular endothelial growth factor receptors (VEGFRs) are part of the evolutionarily conserved VEGF signalling pathways that regulate the development and maintenance of the body\'s cardiovascular and lymphovascular systems. VEGFR3, encoded by the FLT4 gene, has an indispensable and well-characterised function in development and establishment of the lymphatic system. Autosomal dominant VEGFR3 mutations, that prevent the receptor functioning as a homodimer, cause one of the major forms of hereditary primary lymphoedema; Milroy disease. Recently, we and others have shown that FLT4 variants, distinct to those observed in Milroy disease cases, predispose individuals to Tetralogy of Fallot, the most common cyanotic congenital heart disease, demonstrating a novel function for VEGFR3 in early cardiac development. Here, we examine the familiar and emerging roles of VEGFR3 in the development of both lymphovascular and cardiovascular systems, respectively, compare how distinct genetic variants in FLT4 lead to two disparate human conditions, and highlight the research still required to fully understand this multifaceted receptor.

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

Cardiovasc Res: 16 Oct 2020; epub ahead of print

SPEG: a key regulator of cardiac calcium homeostasis.

Campbell H, Aguilar-Sanchez Y, Quick AP, Dobrev D, Wehrens X

Proper cardiac Ca2+ homeostasis is essential for normal excitation-contraction coupling. Perturbations in cardiac Ca2+ handling through altered kinase activity has been implicated in altered cardiac contractility and arrhythmogenesis. Thus, a better understanding of cardiac Ca2+ handling regulation is vital for a better understanding of various human disease processes. \'Striated muscle preferentially expressed protein kinase\' (SPEG) is a member of the myosin light chain kinase family that is key for normal cardiac function. Work within the last five years has revealed that SPEG has a crucial role in maintaining normal cardiac Ca2+ handling through maintenance of transverse tubule formation and phosphorylation of junctional membrane complex proteins. Additionally, SPEG has been causally impacted in human genetic diseases such as centronuclear myopathy and dilated cardiomyopathy as well as in common acquired cardiovascular disease such as heart failure and atrial fibrillation. Given the rapidly emerging role of SPEG as a key cardiac Ca2+ regulator, we here present this review in order to summarize recent findings regarding the mechanisms of SPEG regulation of cardiac excitation-contraction coupling in both physiology and human disease. A better understanding of the roles of SPEG will be important for a more complete comprehension of cardiac Ca2+ regulation in physiology and disease.

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

Cardiovasc Res: 16 Oct 2020; epub ahead of print