The coronavirus disease 2019 caused by SARS-CoV-2 infections imposes a major threat for the world's healthcare systems and is leading to thousands of deaths. Angiotensin-converting enzyme 2 (ACE2) has been identified as a potential receptor for SARS coronavirus 1 and is also considered the main receptor for SARS-CoV-2. 2 SARS-CoV-2 binds to ACE2 via its glycosylated outer membrane spike proteins. ACE2 is highly expressed in the lung and heart, and is known for its vital role in the cardiovascular system. 3-5 Although SARS-CoV-2 mainly invades alveolar epithelial cells, it can also cause myocardial injury, as assessed by increased troponin T and NT-proBNP levels accompanying increased cardiovascular symptoms in COVID-19-infected patients. 6,7 It is unclear whether elevated biomarkers of cardiac injury (or long-term effects on the cardiovascular system) are directly caused by viral infection of cardiac tissue or are secondary to hypoxia and systemic inflammation. However, patients with underlying cardiovascular disease represent a significant proportion of the patients who may suffer from a severe course after COVID-19 infection. 8 This situation may be aggravated by findings showing that ACE inhibitors, which are often used to treat cardiovascular diseases, augment the expression of the SARS-CoV-2 receptor ACE2 in lung cells. 9 This is probably mediated by an effect on angiotensin II, which is known to reduce ACE2 expression. 9 Thus, ACE inhibition decreases angiotensin II, leading to an indirect up-regulation of ACE2. 9 The effect of angiotensin II receptor blockers (ARBs), which primarily target the angiotensin receptor 1, is unclear. One may speculate that ARBs indirectly reduce ACE2 levels by augmenting free angiotensin II levels, which in turn is expected to downregulate ACE2 via activating the angiotensin receptor 2. However, the effect of the two different treatments on the expression of ACE2 in the heart requires further investigation.Therefore, we used single nuclei RNA sequencing to determine the expression of ACE and ACE2 in the different cell types of the human heart. Gene expression signatures were detected in cardiac tissues of five patients with aortic stenosis (AS) and two patients with heart failure with reduced ejection fraction (HFrEF) ( Figure 1A) and compared with with samples of one healthy donor heart (age: 63 years, male) that was not used for transplantation. After single nuclei RNA sequencing, data were pooled, and unsupervised clustering was performed with a total of 57 601 nuclei. We found 18 distinct clusters. Using cell type-specific gene markers, major cell types were annotated, including cardiomyocytes (six clusters), fibroblasts (one cluster), endothelial cells (three clusters), leucocytes (two clusters), pericytes (one cluster), and smooth muscle cells (one cluster) ( Figure 1B-D). ACE2 was expressed in cardiomyocytes (Cluster 0 and 1) and mural cells, particularly pericytes (Cluster 4), and was detected at a lower expression level in fibroblasts, endothelial cell, and leucocytes...

Heart failure is often the consequence of insufficient cardiac regeneration. Neonatal mice retain a certain capability of myocardial regeneration until postnatal day (P)7, although the underlying transcriptional mechanisms remain largely unknown. We demonstrate here that cardiac abundance of the transcription factor GATA4 was high at P1, but became strongly reduced at P7 in parallel with loss of regenerative capacity. Reconstitution of cardiac GATA4 levels by adenoviral gene transfer markedly improved cardiac regeneration after cryoinjury at P7. In contrast, the myocardial scar was larger in cardiomyocyte‐specific Gata4 knockout (CM‐G4‐KO) mice after cryoinjury at P0, indicative of impaired regeneration, which was accompanied by reduced cardiomyocyte proliferation and reduced myocardial angiogenesis in CM‐G4‐KO mice. Cardiomyocyte proliferation was also diminished in cardiac explants from CM‐G4‐KO mice and in isolated cardiomyocytes with reduced GATA4 expression. Mechanistically, decreased GATA4 levels caused the downregulation of several pro‐regenerative genes (among them interleukin‐13, Il13) in the myocardium. Interestingly, systemic administration of IL‐13 rescued defective heart regeneration in CM‐G4‐KO mice and could be evaluated as therapeutic strategy in the future.

A pproximately 5 million Americans have chronic heart failure. 1 The most common causes for the development of chronic heart failure are chronic arterial hypertension, myocardial hypertrophy, and previous myocardial infarction. 1 The progression of heart failure is driven by pathological ventricular remodeling processes, which mainly involve cardiomyocyte hypertrophy, myocardial fibrosis, and profound changes in gene expression that together lead to left ventricular dilation and systolic, and diastolic dysfunction over time. [2][3][4] Despite recent therapeutic advances, the mortality of chronic heart failure remains high, and, a fact that is somewhat neglected, strikingly different between women and men. Women with heart failure have a lower mortality than men and also a better prognosis when experiencing hypertension, aortic valve stenosis, or hypertrophic cardiomyopathy.1,5 Sex hormones might account for these differences, and, indeed, the expression of androgen, and estrogen receptors was found in male and female hearts, implying that estrogen and androgens could directly act on the myocardium. 6,7 Although, in general, estrogen has been deemed cardioprotective, large randomized and controlled studies have failed to demonstrate the beneficial effects of estrogen therapy in postmenopausal women. 8,9 As a consequence, it is now proposed that the rise in cardiovascular mortality in women after the onset of menopause might be caused by an increased ovarian production of testosterone. 10 Clinical Perspective on p 1081Testosterone and its highly active metabolite dihydrotestosterone (DHT) operate by binding to the androgen receptor, Background-In comparison with men, women have a better prognosis when experiencing aortic valve stenosis, hypertrophic cardiomyopathy, or heart failure. Recent data suggest that androgens like testosterone or the more potent dihydrotestosterone contribute to the development of cardiac hypertrophy and failure. Therefore, we analyzed whether antiandrogenic therapy with finasteride, which inhibits the generation of dihydrotestosterone by the enzyme 5-α-reductase, improves pathological ventricular remodeling and heart failure. Methods and Results-We found a strongly induced expression of all 3 isoforms of the 5-α-reductase (Srd5a1 to Srd5a3) in human and mouse hearts with pathological hypertrophy, which was associated with increased myocardial accumulation of dihydrotestosterone. Starting 1 week after the induction of pressure overload by transaortic constriction, mice were treated with finasteride for 2 weeks. Cardiac function, hypertrophy, dilation, and fibrosis were markedly improved in response to finasteride treatment in not only male, but also in female mice. In addition, finasteride also very effectively improved cardiac function and mortality after long-term pressure overload and prevented disease progression in cardiomyopathic mice with myocardial Gαq overexpression. Mechanistically, finasteride, by decreasing dihydrotestosterone, potently inhibited hypertrophy and Akt-dependent p...

Cachexia is associated with poor prognosis in chronic heart failure patients, but the underlying mechanisms of cachexia triggered disease progression remain poorly understood. Here, we investigate whether the dysregulation of myokine expression from wasting skeletal muscle exaggerates heart failure. RNA sequencing from wasting skeletal muscles of mice with heart failure reveals a reduced expression of Ostn, which encodes the secreted myokine Musclin, previously implicated in the enhancement of natriuretic peptide signaling. By generating skeletal muscle specific Ostn knock-out and overexpressing mice, we demonstrate that reduced skeletal muscle Musclin levels exaggerate, while its overexpression in muscle attenuates cardiac dysfunction and myocardial fibrosis during pressure overload. Mechanistically, Musclin enhances the abundance of C-type natriuretic peptide (CNP), thereby promoting cardiomyocyte contractility through protein kinase A and inhibiting fibroblast activation through protein kinase G signaling. Because we also find reduced OSTN expression in skeletal muscle of heart failure patients, augmentation of Musclin might serve as therapeutic strategy.

Pathological cardiac hypertrophy is a leading cause of heart failure, but knowledge of the full repertoire of cardiac cells and their gene expression profiles in the human hypertrophic heart is missing. Here, by using large-scale single-nucleus transcriptomics, we present the transcriptional response of human cardiomyocytes to pressure overload caused by aortic valve stenosis and describe major alterations in cardiac cellular crosstalk. Hypertrophied cardiomyocytes had reduced input from endothelial cells and fibroblasts. Genes encoding Eph receptor tyrosine kinases, particularly EPHB1, were significantly downregulated in cardiomyocytes of the hypertrophied heart. Consequently, EPHB1 activation by its ligand ephrin (EFN)B2, which is mainly expressed by endothelial cells, was reduced. EFNB2 inhibited cardiomyocyte hypertrophy in vitro, while silencing its expression in endothelial cells induced hypertrophy in co-cultured cardiomyocytes. Our human cell atlas of the hypertrophied heart highlights the importance of intercellular crosstalk in disease pathogenesis and provides a valuable resource.

Understanding the transcriptional regulation of angiogenesis could lead to the identification of novel therapeutic targets. We showed here that the transcription factor GATA6 is expressed in different human primary endothelial cells as well as in vascular endothelial cells of mice in vivo. Activation of endothelial cells was associated with GATA6 nuclear translocation, chromatin binding, and enhanced GATA6-dependent transcriptional activation. siRNA-mediated down-regulation of GATA6 after growth factor stimulation led to a dramatically reduced capacity of macro-and microvascular endothelial cells to proliferate, migrate, or form capillary-like structures on Matrigel. Adenoviral overexpression of GATA6 in turn enhanced angiogenic function, especially in cardiac endothelial microvascular cells. Furthermore, GATA6 protected endothelial cells from undergoing apoptosis during growth factor deprivation. Mechanistically, down-regulation of GATA6 in endothelial cells led to increased expression of transforming growth factor (TGF) ␤1 and TGF␤2, whereas enhanced GATA6 expression, accordingly, suppressed Tgfb1 promoter activity. High TGF␤1/␤2 expression in GATA6-depleted endothelial cells increased the activation of the activin receptor-like kinase 5 (ALK5) and SMAD2, and suppression of this signaling axis by TGF␤ neutralizing antibody or ALK5 inhibition restored angiogenic function and survival in endothelial cells with reduced GATA6 expression. Together, these findings indicate that GATA6 plays a crucial role for endothelial cell function and survival, at least in part, by suppressing autocrine TGF␤ expression and ALK5-dependent signaling.Angiogenesis describes the sprouting of new capillaries from the endothelial cells of post-capillary venules (1, 2). It is one of the central processes that controls and enables embryonic and fetal development and that is required to maintain functional and structural integrity of the organism in postnatal life. There are many circumstances in the adult organism (for example, organ ischemia or tumor growth) under which the normally quiescent endothelial cells become activated by growth factors (like VEGF-A, 4 basic fibroblast growth factor, epidermal growth factor) or hypoxia to proliferate, migrate, and interact with each other to form new capillaries (1-3). Although on the one hand research efforts are under way to therapeutically enhance angiogenesis during organ ischemia, on the other hand angiogenesis inhibitors are being developed for cancer therapy (4, 5). To find effective treatment strategies, a detailed understanding of the regulatory signaling pathways that control activation and quiescence of endothelial cells is needed. Although a lot of different growth factors and their receptors have been identified that either facilitate or block angiogenesis, its transcriptional regulation is far less well studied (6). Here we examined the role of the transcription factor GATA6 for angiogenic function and survival in endothelial cells. GATA6 belongs to the family of GATA proteins, of w...

Clonal hematopoiesis of indeterminate potential (CHIP) is linked to leukemia gene mutations and associates with an increased risk for coronary artery disease and poor prognosis in ischemic cardiomyopathy. Two recurrently mutated genes in CHIP and adult acute myeloid leukemia (AML) encode for isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2). Global expression of mutant IDH2 in transgenic mice-induced dilated cardiomyopathy and muscular dystrophy. In this retrospective observational study, we investigated whether mutant IDH1/2 predisposes to cardiovascular disease in AML patients. Among 363 AML patients, IDH1 and IDH2 mutations were detected in 26 (7.2%) and 39 patients (10.7%), respectively. Mutant IDH1 patients exhibited a significantly higher prevalence of coronary artery disease (26.1% vs. 6.4%, p = 0.002). Applying inverse probability-weighting analysis, patients with IDH1/2 mutations had a higher risk for a declining cardiac function during AML treatment compared to IDH1/2 wild type patients [left ventricular ejection fraction pretreatment compared to 10 months after diagnosis: 59.2% to 41.9% (p < 0.001) vs 58.5% to 55.4% (p = 0.27), respectively]. Mechanistically, RNA sequencing and immunostaining in hiPS-derived cardiomyocytes indicated that the oncometabolite R-2HG exacerbated doxorubicin mediated cardiotoxicity. Evaluation of IDH1/2 mutation status may therefore help identifying AML patients at risk for cardiovascular complications during cytotoxic treatment.

Sex hormones influence the prevalence and the outcome of heart diseases. The conversion of testosterone to its more active metabolite dihydrotestosterone drives cardiac growth and dysfunction, while inhibition of this step by the anti-androgenic drug finasteride counteracts these pathological processes in preclinical models. In this retrospective, observational study, we aim to investigate whether finasteride, which is in clinical use mainly for prostate disease, might ameliorate cardiac hypertrophy and heart failure in patients. Retrospective chart review of 1041 medical cases with heart failure between 1995 and 2015 was conducted. Stratification was performed by concomitant prostate treatment status (tamsulosin versus finasteride). A propensity score analysis yielded a total of 328 matched medical cases without residual differences in the baseline patient characteristics. In this propensity score matched samples, anti-androgenic therapy with finasteride was associated with significantly reduced left ventricular hypertrophy (interventricular septal thickness 13.3 ± 2.4 mm control vs. 12.6 ± 2.1 mm finasteride group (p = 0.029); estimated average treatment effects on the treated: −0.7 mm, 95% CI mean difference −1.3 to −0.1). In this retrospective analysis anti-androgenic therapy with finasteride for prostate disease was associated with attenuated cardiac hypertrophy in patients with heart failure. Therefore, our data encourage further analysis of this approach in larger heart failure patient cohorts.