Adipose tissue and blood leukocytes ACE2 DNA methylation in obesity and after weight loss.

BACKGROUND: Obesity was consistently associated with a poor prognosis in patients with COVID-19. Epigenetic mechanisms were proposed as the link between obesity and comorbidities risk. AIM: To evaluate the methylation levels of angiotensin-converting enzyme 2 (ACE2) gene, the main entry receptor of SARS-CoV-2, in different depots of adipose tissue (AT) and leukocytes (PBMCs) in obesity and after weight loss therapy based on a very-low-calorie ketogenic diet (VLCKD), a balanced hypocaloric diet (HCD) or bariatric surgery (BS). MATERIALS AND METHODS: DNA methylation levels of ACE2 were extracted from our data sets generated by the hybridization of subcutaneous (SAT) (n = 32) or visceral (VAT; n = 32) adipose tissue, and PBMCs (n = 34) samples in Infinium HumanMethylation450 BeadChips. Data were compared based on the degree of obesity and after 4-6 months of weight loss either by following a nutritional or surgical treatment and correlated with ACE2 transcript levels. RESULTS: As compared with normal weight, VAT from patients with obesity showed higher ACE2 methylation levels. These differences were mirrored in PBMCs but not in SAT. The observed obesity-associated methylation of ACE2 was reversed after VLCKD and HCD but not after BS. Among the studied CpG sites, cg16734967 and cg21598868, located at the promoter, were the most affected and correlated with BMI. The observed DNA methylation pattern was inversely correlated with ACE2 expression. CONCLUSION: Obesity-related VAT shows hypermethylation and downregulation of the ACE2 gene that is mirrored in PBMCs and is restored after nutritional weight reduction therapy. The results warrant the necessity to further evaluate its implication for COVID-19 pathogenesis.

SARS-CoV-2: Insight in genome structure, pathogenesis and viral receptor binding analysis - An updated review.

The novel coronavirus disease (COVID-19) a global pandemic outbreak is an emerging new virus accountable for respiratory illness caused by SARS-CoV-2, originated in Wuhan city, Hubei province China, urgently calls to adopt prevention and intervention strategies. Several viral epidemics such as severe acute respiratory syndrome coronavirus (SARS-CoV) in 2002 to 2003 and H1N1 influenza in 2009 were reported since last two decades. Moreover, the Saudi Arabia was the epicenter for Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012. The CoVs are large family with single-stranded RNA viruses (+ssRNA). Genome sequence of 2019-nCoV, shows relatively different homology from other coronavirus subtypes, categorized in betacoronavirus and possibly found from strain of bats. The COVID-19 composed of exposed densely glycosylated spike protein (S) determines virus binding and infiltrate into host cells as well as initiate protective host immune response. Recently published reviews on the emerging SARS-CoV-2 have mainly focused on its structure, development of the outbreak, relevant precautions and management trials. Currently, there is an urgency of pharmacological intervention to combat this deadly infectious disease. Elucidation of molecular mechanism of COVID-19 becomes necessary. Based on the current literature and understanding, the aim of this review is to provide current genome structure, etiology, clinical prognosis as well as to explore the viral receptor binding together functional insight of SARS-CoV-2 infection (COVID-19) with treatment and preventive measures.

Higher ACE2 expression levels in epicardial cells than subcutaneous stromal cells from patients with cardiovascular disease: Diabetes and obesity as possible enhancer.

AIMS: Obesity, diabetes and cardiovascular disease are associated with COVID-19 risk and severity. Because epicardial adipose tissue (EAT) expresses ACE2, we wanted to identify the main factors associated with ACE2 levels and its cleavage enzyme, ADAM17, in epicardial fat. MATERIALS AND METHODS: Epicardial and subcutaneous fat biopsies were obtained from 43 patients who underwent open-heart surgery. From 36 patients, biopsies were used for RNA expression analysis by real-time PCR of ACE1, ACE2 and ADAM17. From 8 patients, stromal vascular cells were submitted to adipogenesis or used for studying the treatment effects on gene expression levels. Soluble ACE2 was determined in supernatants by ELISA. RESULTS: Epicardial fat biopsies expressed higher levels of ACE2 (1.53 [1.49-1.61] vs 1.51 [1.47-1.56] a.u., P < .05) and lower ADAM17 than subcutaneous fat (1.67 [1.65-1.70] vs 1.70 [1.66-1.74] a.u., P < .001). Both genes were increased in epicardial fat from patients with type 2 diabetes mellitus (T2DM) (1.62 [1.50-2.28] vs 1.52 [1.49-1.55] a.u., P = .05 for ACE2 and 1.68 [1.66-1.78] vs 1.66 [1.63-1.69] a.u., P < .05 for ADAM17). Logistic regression analysis determined that T2DM was the main associated factor with epicardial ACE2 levels (P < .01). The highest ACE2 levels were found on patients with diabetes and obesity. ACE1 and ACE2 levels were not upregulated by antidiabetic treatment (metformin, insulin or thiazolidinedione). Its cellular levels, which were higher in epicardial than in subcutaneous stromal cells (1.61 [1.55-1.63] vs 1 [1-1.34]), were not correlated with the soluble ACE2. CONCLUSION: Epicardial fat cells expressed higher levels of ACE2 in comparison with subcutaneous fat cells, which is enhanced by diabetes and obesity presence in patients with cardiovascular disease. Both might be risk factors for SARS-CoV-2 infection.

Sex differences in COVID-19: candidate pathways, genetics of ACE2, and sex hormones.

Biological sex is increasingly recognized as a critical determinant of health and disease, particularly relevant to the topical COVID-19 pandemic caused by the SARS-CoV-2 coronavirus. Epidemiological data and observational reports from both the original SARS epidemic and the most recent COVID-19 pandemic have a common feature: males are more likely to exhibit enhanced disease severity and mortality than females. Sex differences in cardiovascular disease and COVID-19 share mechanistic foundations, namely, the involvement of both the innate immune system and the canonical renin-angiotensin system (RAS). Immunological differences suggest that females mount a rapid and aggressive innate immune response, and the attenuated antiviral response in males may confer enhanced susceptibility to severe disease. Furthermore, the angiotensin-converting enzyme 2 (ACE2) is involved in disease pathogenesis in cardiovascular disease and COVID-19, either to serve as a protective mechanism by deactivating the RAS or as the receptor for viral entry, respectively. Loss of membrane ACE2 and a corresponding increase in plasma ACE2 are associated with worsened cardiovascular disease outcomes, a mechanism attributed to a disintegrin and metalloproteinase (ADAM17). SARS-CoV-2 infection also leads to ADAM17 activation, a positive feedback cycle that exacerbates ACE2 loss. Therefore, the relationship between cardiovascular disease and COVID-19 is critically dependent on the loss of membrane ACE2 by ADAM17-mediated proteolytic cleavage. This article explores potential mechanisms involved in COVID-19 that may contribute to sex-specific susceptibility focusing on the innate immune system and the RAS, namely, genetics and sex hormones. Finally, we highlight here the added challenges of gender in the COVID-19 pandemic.

Distinct expression of SARS-CoV-2 receptor ACE2 correlates with endotypes of chronic rhinosinusitis with nasal polyps.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry factors, ACE2 and TMPRSS2, are highly expressed in nasal epithelial cells. However, the association between SARS-CoV-2 and nasal inflammation in chronic rhinosinusitis with nasal polyps (CRSwNP) has not been investigated. We thus investigated the expression of SARS-CoV-2 entry factors in nasal tissues of CRSwNP patients, and their associations with inflammatory endotypes of CRSwNP. METHODS: The expression of ACE2 and TMPRSS2 was assessed in nasal tissues of control subjects and eosinophilic CRSwNP (ECRSwNP) and nonECRSwNP patients. The correlations between ACE2/TMPRSS2 expression and inflammatory indices of CRSwNP endotypes were evaluated. Regulation of ACE2/TMPRSS2 expression by inflammatory cytokines and glucocorticoids was investigated. RESULTS: ACE2 expression was significantly increased in nasal tissues of nonECRSwNP patients compared to ECRSwNP patients and control subjects, and positively correlated with the expression of IFN-γ, but negatively correlated with tissue infiltrated eosinophils, and expression of IL5 and IL13. IFN-γ up-regulated ACE2 expression while glucocorticoid attenuated this increase in cultured nasal epithelial cells. Genes co-expressed with ACE2 were enriched in pathways relating to defence response to virus in nasal tissue. TMPRSS2 expression was decreased in nasal tissues of CRSwNP patients compared to control subjects and not correlated with the inflammatory endotypes of CRSwNP. Glucocorticoid treatment decreased ACE2 expression in nasal tissues of nonECRSwNP patients, but not in ECRSwNP patients, whereas TMPRSS2 expression was not affected. CONCLUSION: These findings indicate that ACE2 expression, regulated by IFN-γ, is increased in nasal tissues of nonECRSwNP patients and positively correlates with type 1 inflammation.

Interferons and viruses induce a novel truncated ACE2 isoform and not the full-length SARS-CoV-2 receptor.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes COVID-19, utilizes angiotensin-converting enzyme 2 (ACE2) for entry into target cells. ACE2 has been proposed as an interferon-stimulated gene (ISG). Thus, interferon-induced variability in ACE2 expression levels could be important for susceptibility to COVID-19 or its outcomes. Here, we report the discovery of a novel, transcriptionally independent truncated isoform of ACE2, which we designate as deltaACE2 (dACE2). We demonstrate that dACE2, but not ACE2, is an ISG. In The Cancer Genome Atlas, the expression of dACE2 was enriched in squamous tumors of the respiratory, gastrointestinal and urogenital tracts. In vitro, dACE2, which lacks 356 amino-terminal amino acids, was non-functional in binding the SARS-CoV-2 spike protein and as a carboxypeptidase. Our results suggest that the ISG-type induction of dACE2 in IFN-high conditions created by treatments, an inflammatory tumor microenvironment or viral co-infections is unlikely to increase the cellular entry of SARS-CoV-2 and promote infection.

Angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker treatment and haemodynamic factors are associated with increased cardiac mRNA expression of angiotensin-converting enzyme 2 in patients with cardiovascular disease.

AIMS: Coronavirus disease 2019 (COVID-19) is a widespread pandemic with an increased morbidity and mortality, especially for patients with cardiovascular diseases. Angiotensin-converting enzyme 2 (ACE2) has been identified as necessary cell entry point for SARS-CoV-2. Previous animal studies have demonstrated an increased ACE2 expression following treatment with either angiotensin-converting enzyme inhibitors (ACEi) or angiotensin II receptor blockers (ARB) that have led to a massive precariousness regarding the optimal cardiovascular therapy during this pandemic. METHODS AND RESULTS: We have measured ACE2 mRNA expression using real-time quantitative polymerase chain reaction in atrial biopsies of 81 patients undergoing coronary artery bypass grafting and we compared 62 patients that received ACEi/ARB vs. 19 patients that were not ACEi/ARB-treated. We found atrial ACE2 mRNA expression to be significantly increased in patients treated with an ACEi or an ARB, independent of potential confounding comorbidities. Interestingly, the cardiac ACE2 mRNA expression correlated significantly with the expression in white blood cells of 22 patients encouraging further evaluation if the latter may be used as a surrogate for the former. Similarly, analysis of 18 ventricular biopsies revealed a significant and independent increase in ACE2 mRNA expression in patients with end-stage heart failure that were treated with ACEi/ARB. On the other hand, cardiac unloading with a left ventricular assist device significantly reduced ventricular ACE2 mRNA expression. CONCLUSION: Treatment with ACEi/ARB is independently associated with an increased myocardial ACE2 mRNA expression in patients with coronary artery disease and in patients with end-stage heart failure. Further trials are needed to test whether this association is deleterious for patients with COVID-19, or possibly protective. Nevertheless, haemodynamic factors seem to be equally important for regulation of cardiac ACE2 mRNA expression.

Cells of the adult human heart.

Cardiovascular disease is the leading cause of death worldwide. Advanced insights into disease mechanisms and therapeutic strategies require a deeper understanding of the molecular processes involved in the healthy heart. Knowledge of the full repertoire of cardiac cells and their gene expression profiles is a fundamental first step in this endeavour. Here, using state-of-the-art analyses of large-scale single-cell and single-nucleus transcriptomes, we characterize six anatomical adult heart regions. Our results highlight the cellular heterogeneity of cardiomyocytes, pericytes and fibroblasts, and reveal distinct atrial and ventricular subsets of cells with diverse developmental origins and specialized properties. We define the complexity of the cardiac vasculature and its changes along the arterio-venous axis. In the immune compartment, we identify cardiac-resident macrophages with inflammatory and protective transcriptional signatures. Furthermore, analyses of cell-to-cell interactions highlight different networks of macrophages, fibroblasts and cardiomyocytes between atria and ventricles that are distinct from those of skeletal muscle. Our human cardiac cell atlas improves our understanding of the human heart and provides a valuable reference for future studies.

Variable Clinical Manifestations of COVID-19: Viral and Human Genomes Talk.

The new coronavirus, known as "SARS-CoV-2"; is the cause of one of the most prevalent infectious viral diseases that was recently announced pandemic by the world health organization. Ongoing research in the fields of prevention, management, and therapy establishes a functional scaffold for clinics during the time of crisis. To obtain this goal, it is necessary that all pathophysiologic aspects of COVID-19 from infection to predisposing backgrounds of infection be identified, so that all the ambiguities of researchers regarding transmission mechanisms, variable clinical manifestation, and therapeutic response can be solved. Here, we firstly discuss about the homology screening between nCoV-2019 and beta-coronavirus family using phylogenetic analyses. Secondly, we analyzed the viral motifs to show that viral entry into the host cells requires a primary activation step performed by FURIN and FURIN-like-mediated enzymatic cleavage on the structural glycoprotein. The cleavage increases viral performance by 1000 folds. We then present a comprehensive view on host cells and the significance of gene variants affecting activation enzymes, supportive entry, and spread mechanisms in humans including renin-angiotensin-aldosterone system (RAAS) a pathway results in certain phenotypes or exacerbate infection-related phenotypes in different organs, hence causes variable clinical manifestations. This is followed by discussing about the importance of personalized medicine in nCoV-2019 exposure. Moreover, chemical drugs prescribed for individuals affected with COVID-19, as well as genes involved in drug transport and metabolisms are reviewed as a prelude to drug response. Finally, we suggest some therapeutic approaches developed based on new methods and technology such as anti-sense therapy and antibodies.