Clinical and Proteomic Correlates of Plasma ACE2 (Angiotensin-Converting Enzyme 2) in Human Heart Failure.

ACE2 (angiotensin-converting enzyme 2) is a key component of the renin-angiotensin-aldosterone system. Yet, little is known about the clinical and biologic correlates of circulating ACE2 levels in humans. We assessed the clinical and proteomic correlates of plasma (soluble) ACE2 protein levels in human heart failure. We measured plasma ACE2 using a modified aptamer assay among PHFS (Penn Heart Failure Study) participants (n=2248). We performed an association study of ACE2 against ≈5000 other plasma proteins measured with the SomaScan platform. Plasma ACE2 was not associated with ACE inhibitor and angiotensin-receptor blocker use. Plasma ACE2 was associated with older age, male sex, diabetes mellitus, a lower estimated glomerular filtration rate, worse New York Heart Association class, a history of coronary artery bypass surgery, and higher pro-BNP (pro-B-type natriuretic peptide) levels. Plasma ACE2 exhibited associations with 1011 other plasma proteins. In pathway overrepresentation analyses, top canonical pathways associated with plasma ACE2 included clathrin-mediated endocytosis signaling, actin cytoskeleton signaling, mechanisms of viral exit from host cells, EIF2 (eukaryotic initiation factor 2) signaling, and the protein ubiquitination pathway. In conclusion, in humans with heart failure, plasma ACE2 is associated with various clinical factors known to be associated with severe coronavirus disease 2019 (COVID-19), including older age, male sex, and diabetes mellitus, but is not associated with ACE inhibitor and angiotensin-receptor blocker use. Plasma ACE2 protein levels are prominently associated with multiple cellular pathways involved in cellular endocytosis, exocytosis, and intracellular protein trafficking. Whether these have a causal relationship with ACE2 or are relevant to novel coronavirus-2 infection remains to be assessed in future studies.

Development of ACE2 autoantibodies after SARS-CoV-2 infection.

BACKGROUND: Activation of the immune system is implicated in the Post-Acute Sequelae after SARS-CoV-2 infection (PASC) but the mechanisms remain unknown. Angiotensin-converting enzyme 2 (ACE2) cleaves angiotensin II (Ang II) resulting in decreased activation of the AT1 receptor and decreased immune system activation. We hypothesized that autoantibodies against ACE2 may develop after SARS-CoV-2 infection, as anti-idiotypic antibodies to anti-spike protein antibodies. METHODS AND FINDINGS: We tested plasma or serum for ACE2 antibodies in 67 patients with known SARS-CoV-2 infection and 13 with no history of infection. None of the 13 patients without history of SARS-CoV-2 infection and 1 of the 20 outpatients that had a positive PCR test for SARS-CoV-2 had levels of ACE2 antibodies above the cutoff threshold. In contrast, 26/32 (81%) in the convalescent group and 14/15 (93%) of patients acutely hospitalized had detectable ACE2 antibodies. Plasma from patients with antibodies against ACE2 had less soluble ACE2 activity in plasma but similar amounts of ACE2 protein compared to patients without ACE2 antibodies. We measured the capacity of the samples to inhibit ACE2 enzyme activity. Addition of plasma from patients with ACE2 antibodies led to decreased activity of an exogenous preparation of ACE2 compared to patients that did not have antibodies. CONCLUSIONS: Many patients with a history of SARS-CoV-2 infection have antibodies specific for ACE2. Patients with ACE2 antibodies have lower activity of soluble ACE2 in plasma. Plasma from these patients also inhibits exogenous ACE2 activity. These findings are consistent with the hypothesis that ACE2 antibodies develop after SARS-CoV-2 infection and decrease ACE2 activity. This could lead to an increase in the abundance of Ang II, which causes a proinflammatory state that triggers symptoms of PASC.

Soluble angiotensin-converting enzyme 2 is transiently elevated in COVID-19 and correlates with specific inflammatory and endothelial markers.

The main entry receptor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is angiotensin-converting enzyme 2 (ACE2). SARS-CoV-2 interactions with ACE2 may increase ectodomain shedding but consequences for the renin-angiotensin system and pathology in Coronavirus disease 2019 (COVID-19) remain unclear. We measured soluble ACE2 (sACE2) and sACE levels by enzyme-linked immunosorbent assay in 114 hospital-treated COVID-19 patients compared with 10 healthy controls; follow-up samples after four months were analyzed for 58 patients. Associations between sACE2 respectively sACE and risk factors for severe COVID-19, outcome, and inflammatory markers were investigated. Levels of sACE2 were higher in COVID-19 patients than in healthy controls, median 5.0 (interquartile range 2.8-11.8) ng/ml versus 1.4 (1.1-1.6) ng/ml, p < .0001. sACE2 was higher in men than women but was not affected by other risk factors for severe COVID-19. sACE2 decreased to 2.3 (1.6-3.9) ng/ml at follow-up, p < .0001, but remained higher than in healthy controls, p = .012. sACE was marginally lower during COVID-19 compared with at follow-up, 57 (45-70) ng/ml versus 72 (52-87) ng/ml, p = .008. Levels of sACE2 and sACE did not differ depending on survival or disease severity. sACE2 during COVID-19 correlated with von Willebrand factor, factor VIII and D-dimer, while sACE correlated with interleukin 6, tumor necrosis factor α, and plasminogen activator inhibitor 1. Conclusions: sACE2 was transiently elevated in COVID-19, likely due to increased shedding from infected cells. sACE2 and sACE during COVID-19 differed in correlations with markers of inflammation and endothelial dysfunction, suggesting release from different cell types and/or vascular beds.

Human Tissue Angiotensin Converting Enzyme (ACE) Activity Is Regulated by Genetic Polymorphisms, Posttranslational Modifications, Endogenous Inhibitors and Secretion in the Serum, Lungs and Heart.

Objective: Inhibitors of the angiotensin converting enzyme (ACE) are the primarily chosen drugs to treat heart failure and hypertension. Moreover, an imbalance in tissue ACE/ACE2 activity is implicated in COVID-19. In the present study, we tested the relationships between circulating and tissue (lung and heart) ACE levels in men. Methods: Serum, lung (n = 91) and heart (n = 72) tissue samples were collected from Caucasian patients undergoing lung surgery or heart transplantation. ACE I/D genotype, ACE concentration and ACE activity were determined from serum and tissue samples. Clinical parameters were also recorded. Results: A protocol for ACE extraction was developed for tissue ACE measurements. Extraction of tissue-localized ACE was optimal in a 0.3% Triton-X-100 containing buffer, resulting in 260 ± 12% higher ACE activity over detergent-free conditions. SDS or higher Triton-X-100 concentrations inhibited the ACE activity. Serum ACE concentration correlated with ACE I/D genotype (II: 166 ± 143 ng/mL, n = 19, ID: 198 ± 113 ng/mL, n = 44 and DD: 258 ± 109 ng/mL, n = 28, p < 0.05) as expected. In contrast, ACE expression levels in the lung tissue were approximately the same irrespective of the ACE I/D genotype (II: 1423 ± 1276 ng/mg, ID: 1040 ± 712 ng/mg and DD: 930 ± 1273 ng/mg, p > 0.05) in the same patients (values are in median ± IQR). Moreover, no correlations were found between circulating and lung tissue ACE concentrations and activities (Spearman's p > 0.05). In contrast, a significant correlation was identified between ACE activities in serum and heart tissues (Spearman's Rho = 0.32, p < 0.01). Finally, ACE activities in lung and the serum were endogenously inhibited to similar degrees (i.e., to 69 ± 1% and 53 ± 2%, respectively). Conclusion: Our data suggest that circulating ACE activity correlates with left ventricular ACE, but not with lung ACE in human. More specifically, ACE activity is tightly coordinated by genotype-dependent expression, endogenous inhibition and secretion mechanisms.

ACE/ACE2 balance might be instrumental to explain the certain comorbidities leading to severe COVID-19 cases.

The outbreak of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is a global catastrophe. The elderly and people with comorbidity are facing a serious complication of the disease. The entry and infection strategy of SARS-CoV-2 in a host cell is raised by an amazing way of angiotensin-converting enzyme (ACE) 2 (ACE2) receptor recognition and imbalance of ACE/ACE2 in various organs, especially in the lungs. Here it has been discussed the role of interferon and protease during the receptor recognition (begining of infection) and followed by the impact of cytokine and hypoxia in the context of the balance of ACE/ACE2. It has also very concisely delineated the biochemistry and mechanism of ACE/ACE2 balance in different stages of infection and its role in comorbidity.

Renin-angiotensin-aldosterone system peptide profiles in patients with COVID-19.

OBJECTIVE: While evidence on the interface between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the renin-angiotensin-aldosterone-system (RAAS) is accumulating, clinical data on RAAS peptide alteration among coronavirus disease-19 (COVID-19) patients is missing. DESIGN AND METHODS: In this exploratory study, we prospectively included adult patients (aged ≥ 18 years) admitted between February 26 and April 30, 2020 to a tertiary care hospital in Switzerland. We assessed the association of an underlying SARS-CoV-2 infection and equilibrium serum levels of RAAS peptides in hospitalized COVID-19 patients 1:1 propensity-score matched with patients suffering from SARS-CoV-2-negative respiratory infections. Subgroup analyses involved stratification for taking RAAS inhibitors. RESULTS: COVID-19 patients had about 50% lower equilibrium serum RAAS peptide levels as compared with matched controls (angiotensin I: 31.6 vs 66.8 pmol/L, -52.7% (95%CI: -68.5% to -36.9%); angiotensin II: 37.7 vs 92.5 pmol/L, -59.2% (95%CI: -72.1% to -46.3%); angiotensin (1-5): 3.3 vs 6.6 pmol/L, -49.7% (95%CI: -59.2% to -40.2%); angiotensin (1-7): 4.8 vs 7.6 pmol/L, -64.9% (95%CI: -84.5% to -45.3%)). While the plasma renin activity was lower in COVID-19 patients (88.6 vs 207.9 pmol/L, -58.5% (95%CI: -71.4% to -45.6%)), there was no difference of angiotensin-converting enzyme (ACE) and ACE2 plasma activity between the groups. Subgroup analyses revealed a pronounced RAAS peptide profile depression in COVID-19 patients among those not on RAAS inhibitors. CONCLUSIONS: As compared with SARS-CoV-2-negative patients, we found a downregulated RAAS in presence of a SARS-CoV-2 infection. Whether the lower levels of the protective angiotensin (1-5) and (1-7) are linked to adverse outcomes in COVID-19 warrants further investigation.

The assessment of serum ACE activity in COVID-19 and its association with clinical features and severity of the disease.

Angiotensin-converting enzyme (ACE)/Angiotensin (Ang) II pathway has crucial regulatory effects on circulatory hemostasis and immune responses. This pathway has a major role in the development of acute lung injury and acute respiratory distress syndrome (ARDS), which is a devastating complication of SARS-CoV-2 infection. The aim of this study is to investigate the serum ACE activity and its correlation with clinical features and the disease severity in patients with COVID-19. Patients with confirmed COVID-19 by detecting SARS-CoV-2 nucleic acid RT-PCR were included in the study. Demographic data, clinical features, laboratory and radiologic investigations were recorded. Patients were classified by disease severity; asymptomatic, mild, and severe pneumonia. The serum ACE activity was evaluated with an autoanalyzer based on a spectrophotometric method. Fifty-five patients (50.9% female) and 18 healthy subjects (33.3 % female) were enrolled in the study. The median age of patients was 40 years, ranging from 22 to 81 years. Eighteen healthy subjects were served as the control group. The baseline characteristics were comparable between groups. The median serum ACE activity of patients and controls (38.00 [IQR 21] U/L and 32.00 [IQR 24] U/L, respectively) and of between patients grouped by disease severity (38.5 [IQR 19], 36 [IQR 25], and 38 [IQR 22] U/L, asymptomatic, mild and severe pneumonia group, respectively) were similar. There was no correlation between the serum ACE activity and conventional inflammatory markers. In this study, we did not find an association between serum ACE activity and COVID-19 and serum ACE activity on admission did not reflect disease severity.

The potential role of serum angiotensin-converting enzyme in coronavirus disease 2019.

BACKGROUND: To explore the clinical significance of serum angiotensin-converting enzyme (ACE) activity in coronavirus disease 2019 (COVID-19). METHODS: In this retrospective study, a total of 136 consecutive patients with confirmed COVID-19 were recruited. Demographic and clinical data were recorded. The serum ACE activity was measured at baseline and during the recovery phase, and its relationship with clinical condition was analyzed. RESULTS: Of the 136 patients with confirmed COVID-19, the 16 severe patients were older and had a higher body mass index (BMI) and proportion of hypertension than the 120 nonsevere patients. In comparison to those of normal controls, the baseline serum ACE activities of subjects in the severe group and nonsevere group were decreased, with the lowest level in the severe group. However, the serum ACE activity increased in the recovery phase, and there were no significant differences among the severe group, nonsevere group and normal control group. CONCLUSION: Serum ACE activity could be used as a marker to reflect the clinical condition of COVID-19 since low activity was associated with the severity of COVID-19 at baseline, and the activity increased with the remission of the disease.

Circulating plasma concentrations of angiotensin-converting enzyme 2 in men and women with heart failure and effects of renin-angiotensin-aldosterone inhibitors.

AIMS: The current pandemic coronavirus SARS-CoV-2 infects a wide age group but predominantly elderly individuals, especially men and those with cardiovascular disease. Recent reports suggest an association with use of renin-angiotensin-aldosterone system (RAAS) inhibitors. Angiotensin-converting enzyme 2 (ACE2) is a functional receptor for coronaviruses. Higher ACE2 concentrations might lead to increased vulnerability to SARS-CoV-2 in patients on RAAS inhibitors. METHODS AND RESULTS: We measured ACE2 concentrations in 1485 men and 537 women with heart failure (index cohort). Results were validated in 1123 men and 575 women (validation cohort).The median age was 69 years for men and 75 years for women. The strongest predictor of elevated concentrations of ACE2 in both cohorts was male sex (estimate = 0.26, P < 0.001; and 0.19, P < 0.001, respectively). In the index cohort, use of ACE inhibitors, angiotensin receptor blockers (ARBs), or mineralocorticoid receptor antagonists (MRAs) was not an independent predictor of plasma ACE2. In the validation cohort, ACE inhibitor (estimate = -0.17, P = 0.002) and ARB use (estimate = -0.15, P = 0.03) were independent predictors of lower plasma ACE2, while use of an MRA (estimate = 0.11, P = 0.04) was an independent predictor of higher plasma ACE2 concentrations. CONCLUSION: In two independent cohorts of patients with heart failure, plasma concentrations of ACE2 were higher in men than in women, but use of neither an ACE inhibitor nor an ARB was associated with higher plasma ACE2 concentrations. These data might explain the higher incidence and fatality rate of COVID-19 in men, but do not support previous reports suggesting that ACE inhibitors or ARBs increase the vulnerability for COVID-19 through increased plasma ACE2 concentrations.

Association of vitamin D with the modulation of the disease severity in COVID-19.

In late 2019, SARS-CoV-2 started to spread throughout the world causing the COVID-19 that has taken a considerable number of lives. Results obtained from several investigations have explained the virus origin, pathogenicity, and transmission. Similar to SARS coronavirus, the pulmonary angiotensin converting enzyme (ACE) 2 was introduced as the virus receptor for entering the cell. An increased body of epidemiological and clinical evidences has shown modulating effects of vitamin D in lung injuries through several mechanisms. Several clinical symptoms as well as molecular factors have shown to be related to the disease transmission and severity. In this study, vitamin D, ACE concentrations, and neutrophil to lymphocyte ratio (NLR) were measured in patients with confirmed COVID-19 in comparison with control group. Results demonstrated significant alterations in vitamin D and ACE levels as well as NLR in the patients' group. Contribution of those factors with the prognosis and severity of the disease has been shown.

Can a Combination of AT1R Antagonist and Vitamin D Treat the Lung Complication of COVID-19?

Severe Acute Respiratory Distress Syndrome caused by a novel human coronavirus SARS-CoV-2 named COVID-19 and declared as a pandemic. This paper reviews the possibility of repurposing angiotensin type 1 receptor (AT1R) antagonists and vitamin D to treat COVID-19. ACE2 protein found on the cell membranes is the target of SARS-CoV-2 for entering into the host cells. Viral spike protein-binding with ACE2 down-regulates it. As ACE2 is known to protect the lung from injuries, SARS-CoV-2-induced ACE2 deficiency may expose patients to lung damage. AT1R antagonists and vitamin D increase the expression of ACE2 independently. Besides, vitamin D suppresses the compensatory increase in renin levels following the inhibition of the renin-angiotensin system by AT1R antagonists. Therefore, a combination of AT1R antagonists and vitamin D may offer protection against COVID-19 induced lung injury.

Men and COVID-19: A Biopsychosocial Approach to Understanding Sex Differences in Mortality and Recommendations for Practice and Policy Interventions.

Data suggest that more men than women are dying of coronavirus disease 2019 (COVID-19) worldwide, but it is unclear why. A biopsychosocial approach is critical for understanding the disproportionate death rate among men. Biological, psychological, behavioral, and social factors may put men at disproportionate risk of death. We propose a stepwise approach to clinical, public health, and policy interventions to reduce COVID-19-associated morbidity and mortality among men. We also review what health professionals and policy makers can do, and are doing, to address the unique COVID-19-associated needs of men.

Assessment of Hypokalemia and Clinical Characteristics in Patients With Coronavirus Disease 2019 in Wenzhou, China.

Importance: Severe acute respiratory syndrome coronavirus 2 has caused a global outbreak of coronavirus disease 2019 (COVID-19). Severe acute respiratory syndrome coronavirus 2 binds angiotensin-converting enzyme 2 of the rennin-angiotensin system, resulting in hypokalemia. Objective: To investigate the prevalence, causes, and clinical implications of hypokalemia, including its possible association with treatment outcomes, among patients with COVID-19. Design, Setting, and Participants: This cohort study was conducted at Wenzhou Central Hospital and Sixth People's Hospital of Wenzhou, Wenzhou, China, from January 11, 2020, to February 15, 2020. Participants included patients who received a diagnosis of COVID-19 according to the criteria issued by the Chinese Health Bureau and were admitted to the hospital. The patients were classified as having severe hypokalemia (plasma potassium <3 mmol/L), hypokalemia (plasma potassium 3-3.5 mmol/L), and normokalemia (plasma potassium >3.5 mmol/L). The clinical features, therapy, and outcomes were compared between the 3 groups. Data analysis was conducted in March 2020. Interventions: The patients were given general support and antiviral therapy. Their epidemiological and clinical features were collected. Main Outcomes and Measures: The prevalence of hypokalemia and response to treatment with potassium supplements were measured by analyzing plasma and urine potassium levels. Results: One hundred seventy-five patients (87 female patients [50%]; mean [SD] age, 45 [14] years) were classified as having severe hypokalemia (31 patients [18%]), hypokalemia (64 patients [37%]), and normokalemia (80 patients [46%]). Patients with severe hypokalemia had statistically significantly higher body temperature (mean [SD], 37.6 °C [0.9 °C]) than the patients with hypokalemia (mean [SD], 37.2 °C [0.7 °C]; difference, 0.4 °C; 95% CI, 0.2-0.6 °C; P = .02) and the patients with normokalemia (mean [SD], 37.1 °C [0.8 °C]; difference, 0.5 °C; 95% CI, 0.3-0.7 °C; P = .005). Patients with higher levels of hypokalemia also had higher creatine kinase levels (severe hypokalemia, mean [SD], 200 [257] U/L [median, 113 U/L; interquartile range {IQR}, 61-242 U/L]; hypokalemia, mean [SD], 97 [85] U/L; and normokalemia, mean [SD], 82 [57] U/L), higher creatine kinase-MB fraction (severe hypokalemia, mean [SD], 32 [39] U/L [median, 14 U/L; IQR, 11-36 U/L]; hypokalemia, mean [SD], 18 [15] U/L; and normokalemia, mean [SD], 15 [8] U/L), higher lactate dehydrogenase levels (mean [SD], severe hypokalemia, 256 [88] U/L; hypokalemia, 212 [59] U/L; and normokalemia, 199 [61] U/L), and higher C-reactive protein levels (severe hypokalemia, mean [SD], 29 [23] mg/L; hypokalemia, mean [SD], 18 [20] mg/L [median, 12, mg/L; IQR, 4-25 mg/L]; and normokalemia, mean [SD], 15 [18] mg/L [median, 6 U/L; IQR, 3-17 U/L]). Of 40 severely and critically ill patients, 34 (85%) had hypokalemia. Patients with severe hypokalemia were given potassium at a dose of 40 mEq per day, for a total mean (SD) of 453 (53) mEq potassium chloride, during the hospital stay. The patients responded well to potassium supplements as they recovered. Conclusions and Relevance: The correction of hypokalemia is challenging because of continuous renal potassium loss resulting from the degradation of angiotensin-converting enzyme 2. The high prevalence of hypokalemia among patients with COVID-19 suggests the presence of disordered rennin-angiotensin system activity, which increases as a result of reduced counteractivity of angiotensin-converting enzyme 2, which is bound by severe acute respiratory syndrome coronavirus 2.