Increased angiotensin-(1-7)-forming activity in failing human heart ventricles: evidence for upregulation of the angiotensin-converting enzyme Homologue ACE2

Role of renin-angiotensin system/angiotensin converting enzyme-2 mechanism and enhanced COVID-19 susceptibility in type 2 diabetes mellitus

Coronavirus disease 2019 (COVID-19) is a disease that caused a global pandemic and is caused by infection of severe acute respiratory syndrome coronavirus 2 virus. It has affected over 768 million people worldwide, resulting in approximately 6900000 deaths. High-risk groups, identified by the Centers for Disease Control and Prevention, include individuals with conditions like type 2 diabetes mellitus (T2DM), obesity, chronic lung disease, serious heart conditions, and chronic kidney disease. Research indicates that those with T2DM face a heightened susceptibility to COVID-19 and increased mortality compared to non-diabetic individuals. Examining the renin-angiotensin system (RAS), a vital regulator of blood pressure and pulmonary stability, reveals the significance of the angiotensin-converting enzyme (ACE) and ACE2 enzymes. ACE converts angiotensin-I to the vasoconstrictor angiotensin-II, while ACE2 counters this by converting angiotensin-II to angiotensin 1-7, a vasodilator. Reduced ACE2 expression, common in diabetes, intensifies RAS activity, contributing to conditions like inflammation and fibrosis. Although ACE inhibitors and angiotensin receptor blockers can be therapeutically beneficial by increasing ACE2 levels, concerns arise regarding the potential elevation of ACE2 receptors on cell membranes, potentially facilitating COVID-19 entry. This review explored the role of the RAS/ACE2 mechanism in amplifying severe acute respiratory syndrome coronavirus 2 infection and associated complications in T2DM. Potential treatment strategies, including recombinant human ACE2 therapy, broad-spectrum antiviral drugs, and epigenetic signature detection, are discussed as promising avenues in the battle against this pandemic.

Counter-regulatory RAS peptides: new therapy targets for inflammation and fibrotic diseases?

The renin-angiotensin system (RAS) is an important cascade of enzymes and peptides that regulates blood pressure, volume, and electrolytes. Within this complex system of reactions, its counter-regulatory axis has attracted attention, which has been associated with the pathophysiology of inflammatory and fibrotic diseases. This review article analyzes the impact of different components of the counter-regulatory axis of the RAS on different pathologies. Of these peptides, Angiotensin-(1-7), angiotensin-(1-9) and alamandine have been evaluated in a wide variety of in vitro and in vivo studies, where not only they counteract the actions of the classical axis, but also exhibit independent anti-inflammatory and fibrotic actions when binding to specific receptors, mainly in heart, kidney, and lung. Other functional peptides are also addressed, which despite no reports associated with inflammation and fibrosis to date were found, they could represent a potential target of study. Furthermore, the association of agonists of the counter-regulatory axis is analyzed, highlighting their contribution to the modulation of the inflammatory response counteracting the development of fibrotic events. This article shows an overview of the importance of the RAS in the resolution of inflammatory and fibrotic diseases, offering an understanding of the individual components as potential treatments.

Adaptive and maladaptive roles of different angiotensin receptors in the development of cardiac hypertrophy and heart failure

Angiotensin II (Ang II) is formed by the action of angiotensin-converting enzyme (ACE) in the renin-angiotensin system. This hormone is known to induce cardiac hypertrophy and heart failure and its actions are mediated by the interaction of both pro- and antihypertrophic Ang II receptors (AT1R and AT2R). Ang II is also metabolized by ACE 2 to Ang-(1-7), which elicits the activation of Mas receptors (MasR) for inducing antihypertrophic actions. Since heart failure under different pathophysiological situations is preceded by adaptive and maladaptive cardiac hypertrophy, we have reviewed the existing literature to gain some information regarding the roles of AT1R, AT2R, and MasR in both acute and chronic conditions of cardiac hypertrophy. It appears that the activation of AT1R may be involved in the development of adaptive and maladaptive cardiac hypertrophy as well as subsequent heart failure because both ACE inhibitors and AT1R antagonists exert beneficial effects. On the other hand, the activation of both AT2R and MasR may prevent the occurrence of maladaptive cardiac hypertrophy and delay the progression of heart failure, and thus therapy with different activators of these antihypertrophic receptors under chronic pathological stages may prove beneficial. Accordingly, it is suggested that a great deal of effort should be made to develop appropriate activators of both AT2R and MasR for the treatment of heart failure subjects.

Angiotensin-converting enzyme 2 in human plasma and lung tissue

PURPOSE

We investigated plasma angiotensin-converting enzyme 2 (ACE2) concentration in a population sample and the ACE2 expression quantitated with the diaminobenzidine mean intensity in the lung tissue in patients who underwent lung surgery.

MATERIALS AND METHODS

The study participants were recruited from a residential area in the suburb of Shanghai for the plasma ACE2 concentration study (n = 503) and the lung tissue samples were randomly selected from the storage in Ruijin Hospital (80 men and 78 age-matched women).

RESULTS

In analyses adjusted for covariables, men had a significantly higher plasma ACE2 concentration (1.21 vs. 0.98 ng/mL, p = 0.027) and the mean intensity of ACE2 in the lung tissue (55.1 vs. 53.9 a.u., p = 0.037) than women. With age increasing, plasma ACE2 concentration decreased (p = 0.001), while the mean intensity of ACE2 in the lung tissue tended to increase (p = 0.087). Plasma ACE2 concentration was higher in hypertension than normotension, especially treated hypertension (1.23 vs. 0.98 ng/mL, p = 0.029 vs. normotension), with no significant difference between users of RAS inhibitors and other classes of antihypertensive drugs (p = 0.64). There was no significance of the mean intensity of ACE2 in the lung tissue between patients taking and those not taking RAS inhibitors (p = 0.14). Neither plasma ACE2 concentration nor the mean intensity of ACE2 in the lung tissue differed between normoglycemia and diabetes (p ≥ 0.20).

CONCLUSION

ACE2 in the plasma and lung tissue showed divergent changes according to several major characteristics of patients.Plain language summary What is the context? • The primary physiological function of ACE2 is the degradation of angiotensin I and II to angiotensin 1-9 and 1-7, respectively. • ACE2 was found to behave as a mediator of the severe acute respiratory syndrome coronavirus (SARS) infection. • There is little research on ACE2 in humans, especially in the lung tissue. • In the present report, we investigated plasma ACE2 concentration and the ACE2 expression quantitated with the diaminobenzidine mean intensity in the lung tissue respectively in two study populations. What is new? • Our study investigated both circulating and tissue ACE2 in human subjects. The main findings were: • In men as well as women, plasma ACE2 concentration was higher in younger than older participants, whereas the mean intensity of ACE2 in the lung tissue increase with age increasing. • Compared with normotension, hypertensive patients had higher plasma ACE2 concentration but similar mean intensity of ACE2 in the lung tissue. • Neither plasma ACE2 concentration nor lung tissue ACE2 expression significantly differed between users of RAS inhibitors and other classes of antihypertensive drugs. What is the impact? • ACE2 in the plasma and lung tissue showed divergent changes according to several major characteristics, such as sex, age, and treated and untreated hypertension. • A major implication is that plasma ACE2 concentration might not be an appropriate surrogate for the ACE2 expression in the lung tissue, and hence not a good predictor of SARS-COV-2 infection or fatality.

The alternative renin-angiotensin system in critically ill patients: pathophysiology and therapeutic implications

The renin-angiotensin system (RAS) plays a crucial role in regulating blood pressure and the cardio-renal system. The classical RAS, mainly mediated by angiotensin I, angiotensin-converting enzyme, and angiotensin II, has been reported to be altered in critically ill patients, such as those in vasodilatory shock. However, recent research has highlighted the role of some components of the counterregulatory axis of the classical RAS, termed the alternative RAS, such as angiotensin-converting Enzyme 2 (ACE2) and angiotensin-(1-7), or peptidases which can modulate the RAS like dipeptidyl-peptidase 3, in many critical situations. In cases of shock, dipeptidyl-peptidase 3, an enzyme involved in the degradation of angiotensin and opioid peptides, has been associated with acute kidney injury and mortality and preclinical studies have tested its neutralization. Angiotensin-(1-7) has been shown to prevent septic shock development and improve outcomes in experimental models of sepsis. In the context of experimental acute lung injury, ACE2 activity has demonstrated a protective role, and its inactivation has been associated with worsened lung function, leading to the use of active recombinant human ACE2, in preclinical and human studies. Angiotensin-(1-7) has been tested in experimental models of acute lung injury and in a recent randomized controlled trial for patients with COVID-19 related hypoxemia. Overall, the alternative RAS appears to have a role in the pathogenesis of disease in critically ill patients, and modulation of the alternative RAS may improve outcomes. Here, we review the available evidence regarding the methods of analysis of the RAS, pathophysiological disturbances of this system, and discuss how therapeutic manipulation may improve outcomes in the critically ill.

From cardiovascular system to brain, the potential protective role of Mas Receptors in COVID-19 infection

Coronavirus disease 2019 (COVID-19) has been declared a new pandemic in March 2020. Although most patients are asymptomatic, those with underlying cardiovascular comorbidities may develop a more severe systemic infection which is often associated with fatal pneumonia. Nonetheless, neurological and cardiovascular manifestations could be present even without respiratory symptoms. To date, no COVID-19-specific drugs are able for preventing or treating the infection and generally, the symptoms are relieved with general anti-inflammatory drugs. Angiotensin-converting-enzyme 2 (ACE2) may function as the receptor for virus entry within the cells favoring the progression of infection in the organism. On the other hand, ACE2 is a relevant enzyme in renin angiotensin system (RAS) cascade fostering Ang1-7/Mas receptor activation which promotes protective effects in neurological and cardiovascular systems. It is known that RAS is composed by two functional countervailing axes the ACE/AngII/AT1 receptor and the ACE/AngII/AT2 receptor which counteracts the actions mediated by AngII/AT1 receptor by inducing anti-inflammatory, antioxidant and anti-growth functions. Subsequently an "alternative" ACE2/Ang1-7/Mas receptor axis has been described with functions similar to the latter protective arm. Here, we discuss the neurological and cardiovascular effects of COVID-19 highlighting the role of the stimulation of the RAS "alternative" protective arm in attenuating pulmonary, cerebral and cardiovascular damages. In conclusion, only two clinical trials are running for Mas receptor agonists but few other molecules are in preclinical phase and if successful these drugs might represent a successful strategy for the treatment of the acute phase of COVID-19 infection.

The Renin Angiotensin System as a Therapeutic Target in Traumatic Brain Injury

Traumatic brain injury (TBI) is a major public health problem, with limited pharmacological options available beyond symptomatic relief. The renin angiotensin system (RAS) is primarily known as a systemic endocrine regulatory system, with major roles controlling blood pressure and fluid homeostasis. Drugs that target the RAS are used to treat hypertension, heart failure and kidney disorders. They have now been used chronically by millions of people and have a favorable safety profile. In addition to the systemic RAS, it is now appreciated that many different organ systems, including the brain, have their own local RAS. The major ligand of the classic RAS, Angiotensin II (Ang II) acts predominantly through the Ang II Type 1 receptor (AT1R), leading to vasoconstriction, inflammation, and heightened oxidative stress. These processes can exacerbate brain injuries. Ang II receptor blockers (ARBs) are AT1R antagonists. They have been shown in several preclinical studies to enhance recovery from TBI in rodents through improvements in molecular, cellular and behavioral correlates of injury. ARBs are now under consideration for clinical trials in TBI. Several different RAS peptides that signal through receptors distinct from the AT1R, are also potential therapeutic targets for TBI. The counter regulatory RAS pathway has actions that oppose those stimulated by AT1R signaling. This alternative pathway has many beneficial effects on cells in the central nervous system, bringing about vasodilation, and having anti-inflammatory and anti-oxidative stress actions. Stimulation of this pathway also has potential therapeutic value for the treatment of TBI. This comprehensive review will provide an overview of the various components of the RAS, with a focus on their direct relevance to TBI pathology. It will explore different therapeutic agents that modulate this system and assess their potential efficacy in treating TBI patients.

Use of Monoclonal Antibodies in Pregnant Women Infected by COVID-19: A Case Series

BACKGROUND

Monoclonal antibodies are designed to target specific proteins of COVID-19 and can be used as a treatment for people with mild to moderate infection and at a high risk of severe disease. Casirivimab/imdevimab, sotrovimab, and Bamlanivimab/etesevimab have been authorized for emergency use in the treatment of COVID-19. However, during pregnancy, these drugs have not been extensively studied.

METHODS

A total of 22 pregnant women with mild to moderate infection were treated with three different monoclonal antibodies, and efficacy and safety were evaluated in the first period and until six months of follow-up.

RESULTS

No infusion/allergic reactions occurred. No fatal or adverse events were observed in the pregnant women or fetus. The time of negativization with sotrovimab was shorter in comparison to Imdevimav/casirivimab (p = 0.0187) and Bamlanivimab/etesevimab (p < 0.00001). The time of negativization with sotrovimab was earlier in comparison to Imdevimav/casirivimab (t-value: 2.92; p = 0.0052) in vaccinated patients and similar in comparison to Imdevimav/casirivimab (t-value: 1.48; p = 0.08). In unvaccinated patients, sotrovimab was faster to achieve negativization in comparison to Bamlanivimab/etesevimab (t-value: 10.75; p < 0.0005).

CONCLUSIONS

Pregnant COVID-19 patients receiving sotrovimab obtained better clinical outcomes. Pregnancy or neonatal complications were not observed after monoclonal treatment, confirming the safety and tolerability of these drugs in pregnant women.

The Role of Renin-Angiotensin System in Diabetic Cardiomyopathy: A Narrative Review

Diabetic cardiomyopathy refers to myocardial dysfunction in type 2 diabetes, but without the traditional cardiovascular risk factors or overt clinical atherosclerosis and valvular disease. The activation of the renin-angiotensin system (RAS), oxidative stress, lipotoxicity, maladaptive immune responses, imbalanced mitochondrial dynamics, impaired myocyte autophagy, increased myocyte apoptosis, and fibrosis contribute to diabetic cardiomyopathy. This review summarizes the studies that address the link between cardiomyopathy and the RAS in humans and presents proposed pathophysiological mechanisms underlying this association. The RAS plays an important role in the development and progression of diabetic cardiomyopathy. The over-activation of the classical RAS axis in diabetes leads to the increased production of angiotensin (Ang) II, angiotensin type 1 receptor activation, and aldosterone release, contributing to increased oxidative stress, fibrosis, and cardiac remodeling. In contrast, Ang-(1-7) suppresses oxidative stress, inhibits tissue fibrosis, and prevents extensive cardiac remodeling. Angiotensin-converting-enzyme (ACE) inhibitors and angiotensin receptor blockers improve heart functioning and reduce the occurrence of diabetic cardiomyopathy. Experimental studies also show beneficial effects for Ang-(1-7) and angiotensin-converting enzyme 2 infusion in improving heart functioning and tissue injury. Further research is necessary to fully understand the pathophysiology of diabetic cardiomyopathy and to translate experimental findings into clinical practice.

Oxalic acid blocked the binding of spike protein from SARS-CoV-2 Delta (B.1.617.2) and Omicron (B.1.1.529) variants to human angiotensin-converting enzymes 2

An epidemic of Corona Virus Disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is spreading worldwide. Moreover, the emergence of SARS-CoV-2 variants of concern, such as Delta and Omicron, has seriously challenged the application of current therapeutics including vaccination and drugs. Relying on interaction of spike protein with receptor angiotensin-converting enzymes 2 (ACE2), SARS-CoV-2 successfully invades to the host cells, which indicates a strategy that identification of small-molecular compounds to block the entry is of great significance for COVID-19 prevention. Our study evaluated the potential efficacy of natural compound oxalic acid (OA) as an inhibitory agent against SARS-CoV-2 invasion, particular on the interaction of the receptor binding domain (RBD) of Delta and Omicron variants to ACE2. By employing a competitive binding assay in vitro, OA significantly blocked the binding of RBDs from Delta B.1.617.2 and Omicron B.1.1.529 to ACE2, but has no effect on the wide-type SARS-CoV-2 strain. Furthermore, OA inhibited the entries of Delta and Omicron pseudovirus into ACE2 high expressing-HEK293T cells. By surface plasmon resonance (SPR) assay, the direct bindings of OA to RBD and ACE2 were analyzed and OA had both affinities with RBDs of B.1.617.2 and B.1.1.529 and with ACE2. Molecular docking predicted the binding sites on the RBD-ACE2 complex and it showed similar binding abilities to both complex of variant Delta or Omicron RBD and ACE2. In conclusion, we provided a promising novel small-molecule compound OA as an antiviral candidate by blocking the cellular entries of SARS-CoV-2 variants.

Artificial Lipid Biomembranes for Full-Length SARS-CoV-2 Receptor

The angiotensin-converting enzyme 2 (ACE2), as a functional receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is essential for assessing potential hosts and treatments. However, many studies are based on its truncated version but not full-length structure. Indeed, a single transmembrane (TM) helix presents in the full-length ACE2, influencing its interaction with SARS-CoV-2. Therefore, synthesis of the full-length ACE2 is an urgent requirement. Here, cell-free membrane protein synthesis systems (CFMPSs) are constructed for full-length membrane proteins. MscL is screened as a model among ten membrane proteins based on their expression and solubility. Next, CFMPSs are constructed and optimized based on natural vesicles, vesicles with four membrane proteins removed or two chaperonins added, and 37 types of nanodiscs. They all increase membrane protein solubility to over 50%. Finally, the full-length ACE2 of 21 species are successfully expressed with yields between 0.4 and 0.9 mg mL^-1 . The definite functional differences from the truncated version suggest that the TM region affects ACE2's structure and function. CFMPSs can be extended to more membrane proteins, paving the way for further applications.

The coronavirus disease pandemic among adult congenital heart disease patients and the lessons learnt - results of a prospective multicenter european registry

Background

At the beginning of the COVID-19 pandemic, professionals in charge of particularly vulnerable populations, such as adult congenital heart disease (ACHD) patients, were confronted with difficult decision-making. We aimed to assess changes in risk stratification and outcomes of ACHD patients suffering from COVID-19 between March 2020 and April 2021.

Methods and results

Risk stratification among ACHD experts (before and after the first outcome data were available) was assessed by means of questionnaires. In addition, COVID-19 cases and the corresponding patient characteristics were recorded among participating centres. Predictors for the outcome of interest (complicated disease course) were assessed by means of multivariable logistic regression models calculated with cluster-robust standard errors. When assessing the importance of general and ACHD specific risk factors for a complicated disease course, their overall importance and the corresponding risk perception among ACHD experts decreased over time. Overall, 638 patients (n = 168 during the first wave and n = 470 during the subsequent waves) were included (median age 34 years, 52% women). Main independent predictors for a complicated disease course were male sex, increasing age, a BMI >25 kg/m2, having ≥2 comorbidities, suffering from a cyanotic heart disease or having suffered COVID-19 in the first wave vs. subsequent waves.

Conclusions

Apart from cyanotic heart disease, general risk factors for poor outcome in case of COVID-19 reported in the general population are equally important among ACHD patients. Risk perception among ACHD experts decreased during the course of the pandemic.

A Review on COVID-19: Primary Receptor, Endothelial Dysfunction, Related Comorbidities, and Therapeutics

Since December 2019, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has caused a global pandemic named coronavirus disease-19 (COVID-19) and resulted in a worldwide economic crisis. Utilizing the spike-like protein on its surface, the SARS-CoV-2 binds to the receptor angiotensin-converting enzyme 2 (ACE2), which highly expresses on the surface of many cell types. Given the crucial role of ACE2 in the renin–angiotensin system, its engagement by SARS-CoV-2 could potentially result in endothelial cell perturbation. This is supported by the observation that one of the most common consequences of COVID-19 infection is endothelial dysfunction and subsequent vascular damage. Furthermore, endothelial dysfunction is the shared denominator among previous comorbidities, including hypertension, kidney disease, cardiovascular diseases, etc., which are associated with an increased risk of severe disease and mortality in COVID-19 patients. Several vaccines and therapeutics have been developed and suggested for COVID-19 therapy. The present review summarizes the relationship between ACE2 and endothelial dysfunction and COVID-19, also reviews the most common comorbidities associated with COVID-19, and finally reviews several categories of potential therapies against COVID-19.

Endothelial dysfunction: developmental mechanisms and therapeutic strategies

Introduction: Every year the importance of the normal functioning of the endothelial layer of the vascular wall in maintaining the health of the body becomes more and more obvious.

The physiological role of the endothelium: The endothelium is a metabolically active organ actively involved in the regulation of hemostasis, modulation of inflammation, maintenance of hemovascular homeostasis, regulation of angiogenesis, vascular tone, and permeability.

Risk factors for the development of endothelial dysfunction: Currently, insufficient bioavailability of nitric oxide is considered the most significant risk factor for endothelial dysfunction.

Mechanisms of development of endothelial dysfunction: The genesis of endothelial dysfunction is a multifactorial process. Among various complex mechanisms, this review examines oxidative stress, inflammation, hyperglycemia, vitamin D deficiency, dyslipidemia, excess visceral fat, hyperhomocysteinemia, hyperuricemia, as well as primary genetic defect of endotheliocytes, as the most common causes in the population underlying the development of endothelial dysfunction.

Markers of endothelial dysfunction in various diseases: This article discusses the main biomarkers of endothelial dysfunction currently used, as well as promising biomarkers in the future for laboratory diagnosis of this pathology.

Therapeutic strategies: Therapeutic approaches to the endothelium in order to prevent or reduce a degree of damage to the vascular wall are briefly described.

Conclusion: Endothelial dysfunction is a typical pathological process involved in the pathogenesis of many diseases. Thus, pharmacological agents with endothelioprotective properties can provide more therapeutic benefits than a drug without such an effect.

A Boolean approach for novel hypoxia-related gene discovery

Hypoxia plays a major role in the etiology and pathogenesis of most of the leading causes of morbidity and mortality, whether cardiovascular diseases, cancer, respiratory diseases or stroke. Despite active research on hypoxia-signaling pathways, the understanding of regulatory mechanisms, especially in specific tissues, still remain elusive. With the accessibility of thousands of potentially diverse genomic datasets, computational methods are utilized to generate new hypotheses. Here we utilized Boolean implication relationship, a powerful method to probe symmetrically and asymmetrically related genes, to identify novel hypoxia related genes. We used a well-known hypoxia-responsive gene, VEGFA, with very large human expression datasets (n = 25,955) to identify novel hypoxia-responsive candidate gene/s. Further, we utilized in-vitro analysis using human endothelial cells exposed to 1% O2 environment for 2, 8, 24 and 48 hours to validate top candidate genes. Out of the top candidate genes (n = 19), 84% genes were previously reported as hypoxia related, validating our results. However, we identified FAM114A1 as a novel candidate gene significantly upregulated in the endothelial cells at 8, 24 and 48 hours of 1% O2 environment. Additional evidence, particularly the localization of intronic miRNA and numerous HREs further support and strengthen our finding. Current results on FAM114A1 provide an example demonstrating the utility of powerful computational methods, like Boolean implications, in playing a major role in hypothesis building and discovery.

Factors Modulating COVID-19: A Mechanistic Understanding Based on the Adverse Outcome Pathway Framework

Addressing factors modulating COVID-19 is crucial since abundant clinical evidence shows that outcomes are markedly heterogeneous between patients. This requires identifying the factors and understanding how they mechanistically influence COVID-19. Here, we describe how eleven selected factors (age, sex, genetic factors, lipid disorders, heart failure, gut dysbiosis, diet, vitamin D deficiency, air pollution and exposure to chemicals) influence COVID-19 by applying the Adverse Outcome Pathway (AOP), which is well-established in regulatory toxicology. This framework aims to model the sequence of events leading to an adverse health outcome. Several linear AOPs depicting pathways from the binding of the virus to ACE2 up to clinical outcomes observed in COVID-19 have been developed and integrated into a network offering a unique overview of the mechanisms underlying the disease. As SARS-CoV-2 infectibility and ACE2 activity are the major starting points and inflammatory response is central in the development of COVID-19, we evaluated how those eleven intrinsic and extrinsic factors modulate those processes impacting clinical outcomes. Applying this AOP-aligned approach enables the identification of current knowledge gaps orientating for further research and allows to propose biomarkers to identify of high-risk patients. This approach also facilitates expertise synergy from different disciplines to address public health issues.

Theoretical Investigation of the Coronavirus SARS-CoV-2 (COVID-19) Infection Mechanism and Selectivity

The SARS-CoV-2 virus, commonly known as COVID-19, first occurred in December 2019 in Wuhan, Hubei Province, China. Since then, it has become a tremendous threat to human health. With a pandemic threat, it is in the significant interest of the scientific world to establish its method of infection. In this manuscript, we combine knowledge of the infection mechanism with theoretical methods to answer the question of the virus’s selectivity. We proposed a two-stage infection mechanism. In the first step, the virus interacts with the ACE2 receptor, with the “proper strength”. When the interaction is too strong, the virus will remain in an “improper position”; if the interaction is too weak, the virus will “run away” from the cell. We also indicated three residues (positions 30, 31, and 353) located on the ACE2 protein-binding interface, which seems to be crucial for successful infection. Our results indicate that these residues are necessary for the initiation of the infection process.

ACE2 suppresses the inflammatory response in LPS-induced porcine intestinal epithelial cells via regulating the NF-κB and MAPK pathways

ACE2 can regulate the development of intestinal inflammatory response, while the effect on LPS-induced inflammatory changes in porcine intestinal epithelial cells is still unclear. The present study investigated the role of ACE2 in inflammatory injury and the possible signaling pathways. The current results show that LPS cause inflammatory damage in IPEC-J2 cells and local RAS system was activated, with a significant correlation. ACE2 gene of IPEC-J2 cells are knocked down, and the inflammatory response are aggravated. ACE2 resist LPS-induced inflammation by degrading Ang II to produce Ang (1-7). The anti-inflammatory effect of ACE2 are mainly achieved by regulating the phosphorylation level of p65 in the NF-κB pathway and ERK1/2 in the MAPK pathway, reducing the expression and release of cellular inflammatory factors. These results reveal the biochemical mechanism of ACE2 against cellular inflammatory response and its potential application.

Does the Fetus Limit Antibiotic Treatment in Pregnant Patients with COVID-19?

During pregnancy, there is a state of immune tolerance that predisposes them to viral infection, causing maternal-fetal vulnerability to the adverse effects of COVID-19. Bacterial coinfections significantly increase the mortality rate for COVID-19. However, it is known that all drugs, including antibiotics, will enter the fetal circulation in a variable degree despite the role of the placenta as a protective barrier and can cause teratogenesis or other malformations depending on the timing of exposure to the drug. Also, it is important to consider the impact of the indiscriminate use of antibiotics during pregnancy can alter both the maternal and fetal-neonatal microbiota, generating future repercussions in both. In the present study, the literature for treating bacterial coinfections in pregnant women with COVID-19 is reviewed. In turn, we present the findings in 50 pregnant women hospitalized diagnosed with SARS-CoV-2 without previous treatment with antibiotics; moreover, a bacteriological culture of sample types was performed. Seven pregnant women had coinfection with Staphylococcus haemolyticus, Staphylococcus epidermidis, Streptococcus agalactiae, Escherichia coli ESBL +, biotype 1 and 2, Acinetobacter jahnsonii, Enterococcus faecium, and Clostridium difficile. When performing the antibiogram, resistance to multiple drugs was found, such as macrolides, aminoglycosides, sulfa, dihydrofolate reductase inhibitors, beta-lactams, etc. The purpose of this study was to generate more scientific evidence on the better use of antibiotics in these patients. Because of this, it is important to perform an antibiogram to prevent abuse of empirical antibiotic treatment with antibiotics in pregnant women diagnosed with SARS-CoV-2.

The evidence for a role of bacteria and viruses in cardiovascular disease

Inflammation plays a critical role in atherosclerosis and cardiovascular disease. Bacteria and viruses are major causative agents of inflammation in the body which normally develops as a response to infection. It is a logical extention, therefore, to believe bacterial and viral infections may be involved in a variety of presentations of cardiovascular diseases. The purpose of this review is to describe the data and conclusions to date on the involvement of these infectious agents in the induction of cardiovascular disease. The review also discusses the various specific bacteria and viruses that have been implicated in cardiovascular disease and the mechanisms, if known, that these agents induce cardiovascular disease.

Sex-Related Factors in Cardiovascular Complications Associated to COVID-19

Coronavirus disease 2019 (COVID-19), the pandemic infection caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), presents with an extremely heterogeneous spectrum of symptoms and signs. The clinical manifestations seem to be correlated with disease severity. COVID-19 susceptibility and mortality show a significant sex imbalance, with men being more prone to infection and showing a higher rate of hospitalization and mortality compared to women. Such variability can be ascribed to both sex-related biological factors and gender-related behavioral cues. This review will discuss the potential mechanisms accounting for sex/gender influence in vulnerability to COVID-19. Cardiovascular diseases play a central role in determining COVID-19 outcome, whether they are pre-existent or arose upon infection. We will pay particular attention to the impact of sex and gender on cardiovascular manifestations related to COVID-19. Finally, we will discuss the sex-dependent variability in some biomarkers for the evaluation of COVID-19 infection and prognosis. The aim of this work is to highlight the significance of gendered medicine in setting up personalized programs for COVID-19 prevention, clinical evaluation and treatment.

ACE2: a key modulator of the renin-angiotensin system and pregnancy

Angiotensin-converting enzyme 2 (ACE2) is a membrane-bound protein containing 805 amino acids. ACE2 shows approximately 42% sequence similarity to somatic ACE but has different biochemical activities. The key role of ACE2 is to catalyze the vasoconstrictor peptide angiotensin (ANG) II to Ang-(1–7), thus regulating the two major counterbalancing pathways of the renin-angiotensin system (RAS). In this way, ACE2 plays a protective role in end-organ damage by protecting tissues from the proinflammatory actions of ANG II. The circulating RAS is activated in normal pregnancy and is essential for maintaining fluid and electrolyte homeostasis and blood pressure. Renin-angiotensin systems are also found in the conceptus. In this review, we summarize the current knowledge on the regulation and function of circulating and uteroplacental ACE2 in uncomplicated and complicated pregnancies, including those affected by preeclampsia and fetal growth restriction. Since ACE2 is the receptor for SARS-CoV-2, and COVID-19 in pregnancy is associated with more severe disease and increased risk of abnormal pregnancy outcomes, we also discuss the role of ACE2 in mediating some of these adverse consequences. We propose that dysregulation of ACE2 plays a critical role in the development of preeclampsia, fetal growth restriction, and COVID-19-associated pregnancy pathologies and suggest that human recombinant soluble ACE2 could be a novel therapeutic to treat and/or prevent these pregnancy complications.

Expression pattern and function of SARS-CoV-2 receptor ACE2

Since the outbreak at the end of 2019, SARS-CoV-2 has been spreading around the world for more than one year. Scientists have been intensely conducting research on this newly emerged coronavirus and the disease caused by it. Angiotensin-converting enzyme 2 (ACE2), as a receptor mediating the cellular entry of SARS-CoV-2, has become a hot spot for researchers. Here, we summarized the recent progresses on the function, expression and distribution characteristics of ACE2 in human body and among populations. We further discussed the interaction mechanism of ACE2 and SARS-CoV-2 S protein, focusing on key residues that effect interaction and binding ability of SARS-CoV-2 variants. This will facilitate researchers to better understand SARS-CoV-2 infection and transmission route, adaptation mechanism, and designing treatment strategies.

The effect of gestational age at the time of diagnosis on adverse pregnancy outcomes in women with COVID-19

Objective

We aimed to investigate the incidence of adverse pregnancy outcomes including preterm birth, preeclampsia (PE), and fetal growth restriction (FGR) in pregnant women with COVID‐19 according to the gestational age.

Methods

This retrospective study included 167 pregnant women who were hospitalized with confirmed COVID‐19. The patients were divided into three groups according to the time of diagnosis as follows: <12 weeks of gestation (first trimester, n = 10), 12–24 weeks of gestation (n = 28), and >24 weeks of gestation (n = 129). Medical records of the patients were reviewed retrospectively and adverse pregnancy outcomes were analyzed.

Results

A total of 49 (29.3%) patients had an active COVID‐19 infection at the time of delivery, while 118 (70.7%) gave birth after the infection was cleared. Twenty‐three patients had preterm birth and the gestational age was <34 weeks in only four of these patients. There was no significant difference in the preterm birth, PE, FGR, HELLP syndrome, and gestational diabetes mellitus among the three gestation groups (p = 0.271, 0.394, 0.403, 0.763, and 0.664, respectively). Four (2.39%) patients required intensive care unit stay. Maternal death was seen in only one (0.59%) patient.

Conclusion

Our study showed no significant correlation between the gestational age at the time of COVID‐19 infection and the frequency of adverse pregnancy outcomes such as preterm birth, PE, FGR, and gestational diabetes mellitus. However, further studies are needed to draw a firm conclusion on this topic.

Soluble angiotensin-converting enzyme levels in heart failure or acute coronary syndrome: revisiting its modulation and prognosis value

The main objective was to compare the meaning of soluble angiotensin-converting enzyme-2 (sACE2) plasma levels modulation on the prognosis of two cohorts of heart failure (HF) and acute coronary syndrome (ACS). We conducted an observational clinical study where sACE2 was measured in two cohorts of HF or ACS (102 patients each), matched by age and gender. The primary endpoint (cardiac death) and the secondary endpoints (non-fatal myocardial infarction or HF readmission) were registered during a 5-year follow-up period. Association with pharmacotherapy was studied, and the effects of cardiovascular drugs on ACE isoforms expression were analysed in human umbilical vein endothelial cells (HUVEC) in vitro. The levels of sACE2 were significantly higher in the HF than ACS cohort. sACE2 was inversely related with the leukocytes number and directly with urea levels. In the ACS cohort, sACE2 was associated with age and glycaemic parameters, but in the HF cohort, the association was with N-terminal pro-B-type natriuretic peptide. The levels of sACE2 were related to long-term prognosis and confirmed as a non-independent predictor in the HF cohort. Soluble ACE2 was higher in patients treated with angiotensin receptors blockers and β-blockers, accordingly with losartan and metoprolol upregulation of ACE1 and ACE2 in HUVECs. Plasma levels of sACE2 were higher in HF than in ACS, independently of age and gender, and were related to long-term cardiac death in the HF cohort. Losartan and metoprolol, but not enalapril, upregulated ACE expression in endothelial cells, accordingly with higher levels of sACE2 in patients using these drugs.

Angiotensin-Converting Enzyme 2 (ACE2) in the Context of Respiratory Diseases and Its Importance in Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection

Angiotensin-Converting Enzyme 2 (ACE2) is an 805 amino acid protein encoded by the ACE2 gene expressed in various human cells, especially in those located in the epithelia. The primary function of ACE2 is to produce angiotensin (1–7) from angiotensin II (Ang II). The current research has described the importance of ACE2 and Ang (1–7) in alternative routes of the renin-angiotensin system (RAS) that promote the downregulation of fibrosis, inflammation, and oxidative stress processes in a great variety of diseases, such as hypertension, acute lung injury, liver cirrhosis, and kidney abnormalities. Investigations into the recent outbreak of the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have revealed the importance of ACE2 during infection and its role in recognizing viral binding proteins through interactions with specific amino acids of this enzyme. Additionally, the ACE2 expression in several organs has allowed us to understand the clinical picture related to the infection caused by SARS-CoV-2. This review aims to provide context for the functions and importance of ACE2 with regards to SARS-CoV-2 in the general clinical aspect and its impact on other diseases, especially respiratory diseases.

Geraniin Inhibits the Entry of SARS-CoV-2 by Blocking the Interaction between Spike Protein RBD and Human ACE2 Receptor

The coronavirus disease 2019 (COVID-19) pandemic is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Despite the development of vaccines, the emergence of SARS-CoV-2 variants and the absence of effective therapeutics demand the continual investigation of COVID-19. Natural products containing active ingredients may be good therapeutic candidates. Here, we investigated the effectiveness of geraniin, the main ingredient in medical plants Elaeocarpus sylvestris var. ellipticus and Nephelium lappaceum, for treating COVID-19. The SARS-CoV-2 spike protein binds to the human angiotensin-converting enzyme 2 (hACE2) receptor to initiate virus entry into cells; viral entry may be an important target of COVID-19 therapeutics. Geraniin was found to effectively block the binding between the SARS-CoV-2 spike protein and hACE2 receptor in competitive enzyme-linked immunosorbent assay, suggesting that geraniin might inhibit the entry of SARS-CoV-2 into human epithelial cells. Geraniin also demonstrated a high affinity to both proteins despite a relatively lower equilibrium dissociation constant (K_D) for the spike protein (0.63 μM) than hACE2 receptor (1.12 μM), according to biolayer interferometry-based analysis. In silico analysis indicated geraniin’s interaction with the residues functionally important in the binding between the two proteins. Thus, geraniin is a promising therapeutic agent for COVID-19 by blocking SARS-CoV-2’s entry into human cells.

The Impact of Angiotensin-Converting Enzyme 2 (ACE2) Expression Levels in Patients with Comorbidities on COVID-19 Severity: A Comprehensive Review

Angiotensin-Converting Enzyme 2 (ACE2) has been proved to be the main host cell receptor for the binding of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for the COVID-19 pandemic. The SARS-CoV-2 spike (S) protein binds to ACE2 to initiate the process of replication. This enzyme is widely present in human organ tissues, such as the heart and lung. The pathophysiology of ACE2 in SARS-CoV-2 infection is complex and may be associated with several factors and conditions that are more severe in COVID-19 patients, such as age, male gender, and comorbidities, namely, cardiovascular diseases, chronic respiratory diseases, obesity, and diabetes. Here we present a comprehensive review that aims to correlate the levels of expression of the ACE2 in patients with comorbidities and with a poor outcome in COVID-19 disease. Significantly higher levels of expression of ACE2 were observed in myocardial and lung tissues in heart failure and COPD patients, respectively. An age-dependent increase in SARS2-CoV-2 receptors in the respiratory epithelium may be also responsible for the increased severity of COVID-19 lung disease in elderly people. Although the role of ACE2 is highlighted regarding the damage that can arise upon the SARS-CoV-2 invasion, there was no association observed between renin-angiotensin-aldosterone system (RAAS) inhibitors and the severity of COVID-19.

A Novel Therapeutic Peptide Blocks SARS-CoV-2 Spike Protein Binding with Host Cell ACE2 Receptor

Background and Objective

Coronavirus disease 2019 is a novel disease caused by the severe acute respiratory syndrome coronavirus (SARS-CoV)-2 virus. It was first detected in December 2019 and has since been declared a pandemic causing millions of deaths worldwide. Therefore, there is an urgent need to develop effective therapeutics against coronavirus disease 2019. A critical step in the crosstalk between the virus and the host cell is the binding of the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein to the peptidase domain of the angiotensin-converting enzyme 2 (ACE2) receptor present on the surface of host cells.

Methods

An in silico approach was employed to design a 13-amino acid peptide inhibitor (13AApi) against the RBD of the SARS-CoV-2 spike protein. Its binding specificity for RBD was confirmed by molecular docking using pyDockWEB, ClusPro 2.0, and HDOCK web servers. The stability of 13AApi and the SARS-CoV-2 spike protein complex was determined by molecular dynamics simulation using the GROMACS program while the physicochemical and ADMET (absorption, distribution, metabolism, excretion, and toxicity) properties of 13AApi were determined using the ExPASy tool and pkCSM server. Finally, in vitro validation of the inhibitory activity of 13AApi against the spike protein was performed by an enzyme-linked immunosorbent assay.

Results

In silico analyses indicated that the 13AApi could bind to the RBD of the SARS-CoV-2 spike protein at the ACE2 binding site with high affinity. In vitro experiments validated the in silico findings, showing that 13AApi could significantly block the RBD of the SARS-CoV-2 spike protein.

Conclusions

Blockage of binding of the SARS-CoV-2 spike protein with ACE2 in the presence of the 13AApi may prevent virus entry into host cells. Therefore, the 13AApi can be utilized as a promising therapeutic agent to combat coronavirus disease 2019.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40268-021-00357-0.

Mutational analysis in international isolates and drug repurposing against SARS-CoV-2 spike protein: molecular docking and simulation approach

The novel SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) is spreading, as the causative pathogen of coronavirus disease-19 (COVID-19). It has infected more than 1.65 billion people all over the world since it was discovered and reported 3.43 million deaths by mid of May 2021. SARS-CoV-2 enters the host cell by binding to viral surface glycoprotein (S protein) with human ACE2 (angiotensin-converting enzyme2). Spike protein (contains S1 and S2 sub-domains) molecular interaction with the host cells is considered as a major step in the viral entry and disease initiation and progression and this identifies spike protein as a promising therapeutic target against antiviral drugs. Currently, there are no efficient antiviral drugs for the prevention of COVID-19 infection. In this study, we have analyzed global 8719 spike protein sequences from patients infected with SAR-CoV-2. These SAR-CoV-2 genome sequences were downloaded from the GISAID database. By using an open reading frame (ORF) tool we have identified the spike protein sequence. With these, all spike protein amino acid sequences are subjected to multiple sequence alignment (MSA) with Wuhan strain spike protein sequence as a query sequence, and it shows all SAR-CoV strain spike proteins are 99.8% identical. In the mutational analysis, we found 639 mutations in the spike protein sequence of SARS-CoV-2 and identified/highlighted 20 common mutations L5F, T22I, T29I, H49Y, L54F, V90F, S98F, S221L, S254F, V367F, A520S, T572I, D614G, H655Y, P809S, A879S, D936Y, A1020S, A1078S, and H1101Y. Further, we have analyzed the crystal structure of the 2019-nCoV chimeric receptor-binding complex with ACE2 (PDB ID: 6VW1) as a major target protein. The spike receptor binding protein (RBD) used as target region for our studies with FDA-approved drugs for repurposing, and identified few anti-SARS-CoV2 potential drugs (Silmitasertib, AC-55541, Merimepodib, XL413, AZ3451) based on their docking score and binding mode calculations expected to strongly bind to motifs of ACE2 receptor and may show impart relief in COVID-19 patients.

Therapeutic targets of natural products for the management of cardiovascular symptoms of coronavirus disease 2019

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first occurred in China in December 2019 and subsequently spread all over the world with cardiovascular, renal, and pulmonary symptoms. Therefore, recognizing and treating the cardiovascular sign and symptoms that caused by coronavirus disease 2019 (COVID-19) can be effective in reducing patient mortality. To control the COVID-19-related cardiovascular symptoms, natural products are considered one of the promising choices as complementary medicine. Scientists are struggling to discover new antiviral agents specific to this virus. In this review, the natural products for management of cardiovascular symptoms of COVID-19 are categorized into three groups: (a) natural products with an impact on angiotensin II type 1 receptor; (b) natural products that inhibit angiotensin-converting enzyme activity; and (c) natural products that mimic adenosine activity. All these natural products should undergo clinical investigations to test their efficacy, safety, and toxicity in the treatment of cardiovascular symptoms of COVID-19. This article summarizes agents with potential efficacy against COVID-19-related cardiovascular symptoms.

Regulated Intramembrane Proteolysis of ACE2: A Potential Mechanism Contributing to COVID-19 Pathogenesis?

Since being identified as a key receptor for SARS-CoV-2, Angiotensin converting enzyme 2 (ACE2) has been studied as one of the potential targets for the development of preventative and/or treatment options. Tissue expression of ACE2 and the amino acids interacting with the spike protein of SARS-CoV-2 have been mapped. Furthermore, the recombinant soluble extracellular domain of ACE2 is already in phase 2 trials as a treatment for SARS-CoV-2 infection. Most studies have continued to focus on the ACE2 extracellular domain, which is known to play key roles in the renin angiotensin system and in amino acid uptake. However, few also found ACE2 to have an immune-modulatory function and its intracellular tail may be one of the signaling molecules in regulating cellular activation. The implication of its immune-modulatory role in preventing the cytokine-storm, observed in severe COVID-19 disease outcomes requires further investigation. This review focuses on the regulated proteolytic cleavage of ACE2 upon binding to inducer(s), such as the spike protein of SARS-CoV, the potential of cleaved ACE2 intracellular subdomain in regulating cellular function, and the ACE2's immune-modulatory function. This knowledge is critical for targeting ACE2 levels for developing prophylactic treatment or preventative measures in SARS-CoV infections.

Genetic and epigenetic control of ACE2 expression and its possible role in COVID-19

Coronavirus disease 2019 (COVID‐19), caused by severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2), is a pandemic that is claiming hundreds of thousands of lives around the world. Angiotensin‐converting enzyme‐2 (ACE2) is a key player in COVID‐19 due to its pivotal role in the SARS‐CoV‐2 infection. This enzyme is expressed throughout the body and the studies conducted so far have shown that its expression varies according to several factors, including cell type, sex, age, disease states and probably SARS‐CoV‐2 infection. Single‐nucleotide polymorphisms (SNPs) and epigenetic mechanisms, including DNA methylation, histone post‐translational modifications and microRNAs, impact ACE2 expression and may explain structural variation. The understanding of how genetic variants and epigenetic markers act to control ACE2 expression in health and disease states may contribute to comprehend several aspects of COVID‐19 that are puzzling researchers and clinicians. This review collects and appraises the literature regarding some aspects in the ACE2 biology, the expression patterns of this molecule, SNPs of the ACE2 gene and epigenetic mechanisms that may impact ACE2 expression in the context of COVID‐19.

Effects of SARS-CoV-2 infection on human reproduction

The worldwide infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) impacts human health and life on multiple levels. People infected with SARS-CoV-2 suffer from physical disorders and psychological distress. At present, no direct evidence indicates that SARS-CoV-2 negatively influences human reproduction, and the possibility that gametes and embryos are affected requires further investigation. To evaluate the potential effects of SARS-CoV-2 infection on human reproduction and fetal health, this review summarizes the basic and clinical research of SARS-CoV-2 on reproduction up to date, hoping to offer guidance and advice to people at reproductive age and provide clues for the prevention and treatment of associated diseases.

Therapy with RAS inhibitors during the COVID-19 pandemic

Coronavirus disease 2019 (COVID-19) is caused by the novel coronavirus first identified in Wuhan, China. The global number of confirmed cases of COVID-19 has surpassed 28,285,700 with mortality that appears higher than for seasonal influenza. About 20% of COVID-19 patients have experienced cardiac involvement and myocardial infarction in patients infected with SARS-CoV-2 had a worse prognosis. Furthermore, the widespread use of antiviral drugs can be linked to a worsening of heart function. Arrhythmias and hypertension have also been reported in patients with Covid-19. On the other hand, previous cardiac diseases are present in 30% of patients infected with SARS-CoV-2. There is uncertainty in the use of ace inhibitors and angiotensin II (Ang II) antagonists in the COVID-19 era. The mechanism of action of SARS-CoV-2 has been elucidated. It has been demonstrated that angiotensin-converting enzyme 2 (ACE2) is the cellular receptor for the new coronavirus SARS-CoV-2 and it is required for host cell entry and subsequent viral replication. The effect of the SARS-CoV-2 infection is the downregulation of ACE2 that may contribute to the severity of lung pathologies as well as the cardiac function. ACE2, a homolog of ACE, is a monocarboxypeptidase that converts Ang II into angiotensin 1-7 (Ang 1-7) that with its vasodilatory, antifibrotic, antihypertrophic effects counterbalances the negative effects of Ang II. On the other hand, angiotensin-converting enzyme inhibitors (ACEi) and AT1R blockers have been shown to upregulate the expression of ACE2. Based on the mechanism of action of SARS-CoV-2, the use of renin angiotensin system (RAS) inhibitors was questioned although all scientific societies did not recommend discontinuation when clinically recommended. The BRACE CORONA, a phase 4, randomized study tested two strategies: temporarily stopping the ACE inhibitor/angiotensin receptor blockers (ARB) for 30 days versus continuing ACE inhibitors/ARBs in patients who were taking these medications chronically and were hospitalized with a confirmed diagnosis of COVID-19 was also discussed. Therefore, the goal of this review is to summarize recent laboratory and clinical investigations concerning the use of ACEi and ARBs during the COVID-19 pandemic. The available data, based also on a randomized trial, suggest that ACEIs or ARBs, when clinically indicated, should be regularly used in the COVID-19 era.

A comprehensive guide to the pharmacologic regulation of angiotensin converting enzyme 2 (ACE2), the SARS-CoV-2 entry receptor

The recent emergence of coronavirus disease-2019 (COVID-19) as a global pandemic has prompted scientists to address an urgent need for defining mechanisms of disease pathology and treatment. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent for COVID-19, employs angiotensin converting enzyme 2 (ACE2) as its primary target for cell surface attachment and likely entry into the host cell. Thus, understanding factors that may regulate the expression and function of ACE2 in the healthy and diseased body is critical for clinical intervention. Over 66% of all adults in the United States are currently using a prescription drug and while earlier findings have focused on possible upregulation of ACE2 expression through the use of renin angiotensin system (RAS) inhibitors, mounting evidence suggests that various other widely administered drugs used in the treatment of hypertension, heart failure, diabetes mellitus, hyperlipidemias, coagulation disorders, and pulmonary disease may also present a varied risk for COVID-19. Specifically, we summarize mechanisms on how heparin, statins, steroids and phytochemicals, besides their established therapeutic effects, may also interfere with SARS-CoV-2 viral entry into cells. We also describe evidence on the effect of several vitamins, phytochemicals, and naturally occurring compounds on ACE2 expression and activity in various tissues and disease models. This comprehensive review aims to provide a timely compendium on the potential impact of commonly prescribed drugs and pharmacologically active compounds on COVID-19 pathology and risk through regulation of ACE2 and RAS signaling.

COVID-19 and Cardiovascular Disease: From Bench to Bedside

A pandemic of historic impact, coronavirus disease 2019 (COVID-19) has potential consequences on the cardiovascular health of millions of people who survive infection worldwide. Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2), the etiologic agent of COVID-19, can infect the heart, vascular tissues, and circulating cells through ACE2 (angiotensin-converting enzyme 2), the host cell receptor for the viral spike protein. Acute cardiac injury is a common extrapulmonary manifestation of COVID-19 with potential chronic consequences. This update provides a review of the clinical manifestations of cardiovascular involvement, potential direct SARS-CoV-2 and indirect immune response mechanisms impacting the cardiovascular system, and implications for the management of patients after recovery from acute COVID-19 infection.

Drug screening and development from the affinity of S protein of new coronavirus with ACE2

Recently, various studies have shown that angiotensin-converting enzyme 2 (ACE2) acts as the "doorknob" that can be bound by the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which conduces to its entrance to the host cells, and plays an important role in corona virus disease 2019 (COVID-19). This paper aims to collect and sorts out the existing drugs, which exert the ability to block the binding of S protein and ACE2 so as to provide directions for the later drug development. By reviewing the existing literature, we expound the pathogenesis of SARS-CoV-2 from the perspective of S protein and ACE2 binding, and summarize the drugs and compounds that can interfere with the interaction of spike protein and ACE2 receptor from different ways. We summarized five kinds of substances, including peptide P6, griffithsin, hr2p analogs, EK1, vaccine, monoclonal antibody, cholesterol-depleting agents, and extracts from traditional Chinese medicine. They can fight SARS-CoV-2 by specifically binding to ACE2 receptor, S protein, or blocking membrane fusion between the host and virus. ACE2 is the key point for SARS-CoV-2 to enter the cells, and it is also the focus of drug intervention. Our drug summary on this pathomechanism is expected to provide ideas for the drug research on SARS-CoV-2 and help to develop anti-coronavirus drugs of broad spectrum for future epidemics.

Pulmonary, cardiac and renal distribution of ACE2, furin, TMPRSS2 and ADAM17 in rats with heart failure: Potential implication for COVID-19 disease

Congestive heart failure (CHF) is often associated with kidney and pulmonary dysfunction. Activation of the renin-angiotensin-aldosterone system (RAAS) contributes to avid sodium retention, cardiac hypertrophy and oedema formation, including lung congestion. While the status of the classic components of RAAS such as renin, angiotensin converting enzyme (ACE), angiotensin II (Ang II) and angiotensin II receptor AT-1 is well studied in CHF, the expression of angiotensin converting enzyme-2 (ACE2), a key enzyme of angiotensin 1-7 (Ang 1-7) generation in the pulmonary, cardiac and renal systems has not been studied thoroughly in this clinical setting. This issue is of a special interest as Ang 1-7 counterbalance the vasoconstrictory, pro-inflammatory and pro-proliferative actions of Ang II. Furthermore, CHF predisposes to COVID-19 disease severity, while ACE2 also serves as the binding domain of SARS-CoV-2 in human host-cells, and acts in concert with furin, an important enzyme in the synthesis of BNP in CHF, in permeating viral functionality along TMPRSST2. ADAM17 governs ACE2 shedding from cell membranes. Therefore, the present study was designed to investigate the expression of ACE2, furin, TMPRSS2 and ADAM17 in the lung, heart and kidneys of rats with CHF to understand the exaggerated susceptibility of clinical CHF to COVID-19 disease. Heart failure was induced in male Sprague Dawley rats by the creation of a surgical aorto-caval fistula. Sham-operated rats served as controls. One week after surgery, the animals were subdivided into compensated and decompensated CHF according to urinary sodium excretion. Both groups and their controls were sacrificed, and their hearts, lungs and kidneys were harvested for assessment of tissue remodelling and ACE2, furin, TMPRSS2 and ADAM17 immunoreactivity, expression and immunohistochemical staining. ACE2 immunoreactivity and mRNA levels increased in pulmonary, cardiac and renal tissues of compensated, but not in decompensated CHF. Furin immunoreactivity was increased in both compensated and decompensated CHF in the pulmonary, cardiac tissues and renal cortex but not in the medulla. Interestingly, both the expression and abundance of pulmonary, cardiac and renal TMPRSS2 decreased in CHF in correlation with the severity of the disease. Pulmonary, cardiac and renal ADAM17 mRNA levels were also downregulated in decompensated CHF. Circulating furin levels increased in proportion to CHF severity, whereas plasma ACE2 remained unchanged. In summary, ACE2 and furin are overexpressed in the pulmonary, cardiac and renal tissues of compensated and to a lesser extent of decompensated CHF as compared with their sham controls. The increased expression of the ACE2 in heart failure may serve as a compensatory mechanism, counterbalancing the over-activity of the deleterious isoform, ACE. Downregulated ADAM17 might enhance membranal ACE2 in COVID-19 disease, whereas the suppression of TMPRSS2 in CHF argues against its involvement in the exaggerated susceptibility of CHF patients to SARS-CoV2.

Neurohormonal modulation in pulmonary arterial hypertension

Pulmonary hypertension is a fatal condition of elevated pulmonary pressures, complicated by right heart failure. Pulmonary hypertension appears in various forms; one of those is pulmonary arterial hypertension (PAH) and is particularly characterised by progressive remodelling and obstruction of the smaller pulmonary vessels. Neurohormonal imbalance in PAH patients is associated with worse prognosis and survival. In this back-to-basics article on neurohormonal modulation in PAH, we provide an overview of the pharmacological and nonpharmacological strategies that have been tested pre-clinically and clinically. The benefit of neurohormonal modulation strategies in PAH patients has been limited by lack of insight into how the neurohormonal system is changed throughout the disease and difficulties in translation from animal models to human trials. We propose that longitudinal and individual assessments of neurohormonal status are required to improve the timing and specificity of neurohormonal modulation strategies. Ongoing developments in imaging techniques such as positron emission tomography may become helpful to determine neurohormonal status in PAH patients in different disease stages and optimise individual treatment responses.

The serum angiotensin-converting enzyme 2 and angiotensin-(1-7) concentrations after optimal therapy for acute decompensated heart failure with reduced ejection fraction

Objective: Elucidation of the role of angiotensin-converting enzyme (ACE) 2 (ACE2)/angiotensin (Ang)-(1-7)/Mas receptor axis in heart failure is necessary. No previous study has reported serial changes in ACE2 and Ang-(1-7) concentrations after optimal therapy (OT) in acute heart failure (AHF) patients. We aimed to investigate serial changes in serum ACE2 and Ang-(1-7) concentrations after OT in AHF patients with reduced ejection fraction (EF).

Methods: ACE2 and Ang-(1-7) concentrations were measured in 68 AHF patients with reduced EF immediately after admission and 1 and 3 months after OT. These parameters were compared with the healthy individuals at three time points.

Results: In the acute phase, Ang-(1-7) and ACE2 concentrations was statistically significantly lower and higher in AHF patients than the healthy individuals (2.40 ± 1.11 vs. 3.1 ± 1.1 ng/ml, P<0.005 and 7.45 ± 3.13 vs. 4.84 ± 2.25 ng/ml, P<0.005), respectively. At 1 month after OT, Ang-(1-7) concentration remained lower in AHF patients than the healthy individuals (2.37 ± 1.63 vs. 3.1 ± 1.1 ng/ml, P<0.05); however, there was no statistically significant difference in ACE2 concentration between AHF patients and the healthy individuals. At 3 months after OT, there were no statistically significant differences in Ang-(1-7) and ACE2 concentrations between AHF patients and the healthy individuals.

Conclusion: ACE2 concentration was equivalent between AHF patients and the healthy individuals at 1 and 3 months after OT, and Ang-(1-7) concentration was equivalent at 3 months after OT.

Eyes on coronavirus

Recently, coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 has spread around the world and is receiving worldwide attention. Approximately 20% of infected patients are suffering from severe disease of multiple systems and in danger of death, while the ocular complications of SARS-CoV-2-infected patients have not been reported generally. Herein, we focus on two major receptors of SARS-CoV-2, ACE2 and CD147 (BSG), in human ocular cells, and interpret the potential roles of coronaviruses in human ocular tissues and diseases.

Expression of SARS-COV-2 cell receptor gene ACE2 is associated with immunosuppression and metabolic reprogramming in lung adenocarcinoma based on bioinformatics analyses of gene expression profiles

The aberrant expression level of SARS-CoV-2 cell receptor gene ACE2 was reported in lung adenocarcinoma (LUAD) comorbidity of COVID-19. However, the association of ACE2 expression levels with immunosuppression and metabolic reprogramming in LUAD remains lacking. We investigated the expression level of ACE2, an association of ACE2 expression level with various types of immune signatures, immune ratios, and pathways. We employed a weighted gene co-expression network analysis (WGCNA) R package to identify the gene modules and investigated prognostic roles of hub genes in LUAD. Overexpression of ACE2 level was found in LUAD and ACE2 expression was negatively associated with various types of immune signatures including CD8⁺ T cells, CD4⁺ regulatory T cells, NK cells, and T cell activation. Besides, ACE2 upregulation was not only associated with CD8⁺ T cell/CD4+ regulatory T cell ratios but also linked with downregulation of immune-markers including CD8A, KLRC1, GZMA, GZMB, NKG7, CCL4, and IFNG. Moreover, the ACE2 expression level was found to be associated with the enrichment level of various metabolic pathways and it was also found that the metabolic pathways are directly positively correlated with the increased expression levels of ACE2, indicating that the overexpression of ACE2 is associated with metabolic reprogramming in LUAD. Furthermore, WGCNA based analysis revealed the gene modules in the high-ACE2-expression-level group of LUAD and identified GCLC and SLC7A11 hub genes which are not only highly expressed in lung adenocarcinoma but also correlated with the poor survival prognosis. Our analysis of ACE2 in LUAD tissues suggests that ACE2 is not only a receptor but is also associated with immunosuppression and metabolic reprogramming. This study underlines the clue for understanding the clinical significance of ACE2 in COVID-19 patients with LUAD comorbidity.

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The expression level of ACE2 is negatively associated with the immune signatures.

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ACE2 upregulation also linked with the downregulation of immune-markers.

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The ACE2 expression level is positively associated with the metabolic pathways.

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WGCNA based analysis revealed the gene modules in a high-ACE2-expression-level group.

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Highly expressed GCLC and SLC7A11 hub genes are correlated with the poor prognosis.

Renin-angiotensin system at the interface of COVID-19 infection

Angiotensin-converting enzyme 2 (ACE2) has been recognized as a potential entry receptor for SARS-CoV-2 infection. Binding of SARS-CoV-2 to ACE2 allows engagement with pulmonary epithelial cells and pulmonary infection with the virus. ACE2 is an essential component of renin-angiotensin system (RAS), and involved in promoting protective effects to counter-regulate angiotensin (Ang) II-induced pathogenesis. The use of angiotensin receptor blockers (ARBs) and ACE inhibitors (ACEIs) was implicitly negated during the early phase of COVID-19 pandemic, considering the role of these antihypertensive agents in enhancing ACE2 expression thereby promoting the susceptibility to SARS-CoV-2. However, no clinical data has supported this assumption, but indeed evidence demonstrates that ACEIs and ARBs, besides their cardioprotective effects in COVID-19 patients with cardiovascular diseases, might also be beneficial in acute lung injuries by preserving the ACE2 function and switching the balance from deleterious ACE/Ang II/AT1 receptor axis towards a protective ACE2/Ang (1-7)/Mas receptor axis.

Receptors | Angiotensin Receptors

The renin-angiotensin-aldosterone system (RAS) is a vital hormone-receptor system that regulates cardiovascular and renal functions. In this article, we discuss exciting new findings in the RAS field. Recently solved active state crystal structures of Angiotensin II type 1 (AT1R) and type 2 receptor (AT2R) helped in understanding receptor activation mechanisms in detail. Also, considerable attention is given to the developments in characterizing the counter-regulatory RAS axis due to current hope for harnessing this axis for the development of protective therapies against various cardiovascular diseases. We describe the RAS component, angiotensin-converting enzyme 2 (ACE2) functioning as cellular entry receptor for the causative agent of COVID-19 pandemic, SARS-CoV-2. Altogether, these discoveries paved the way for developing novel therapies targeting different components of the RAS in the future.

Inhibition of SARS-CoV-2 Entry into Host Cells Using Small Molecules

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), a virus belonging to the Coronavirus family, is now known to cause Coronavirus Disease (Covid-19) which was first recognized in December 2019. Covid-19 leads to respiratory illnesses ranging from mild infections to pneumonia and lung failure. Strikingly, within a few months of its first report, Covid-19 has spread worldwide at an exceptionally high speed and it has caused enormous human casualties. As yet, there is no specific treatment for Covid-19. Designing inhibitory drugs that can interfere with the viral entry process constitutes one of the main preventative therapies that could combat SARS-CoV-2 infection at an early stage. In this review, we provide a brief introduction of the main features of coronaviruses, discuss the entering mechanism of SARS-CoV-2 into human host cells and review small molecules that inhibit SARS-CoV-2 entry into host cells. Specifically, we focus on small molecules, identified by experimental validation and/or computational prediction, that target the SARS-CoV-2 spike protein, human angiotensin converting enzyme 2 (ACE2) receptor and the different host cell proteases that activate viral fusion. Given the persistent rise in Covid-19 cases to date, efforts should be directed towards validating the therapeutic effectiveness of these identified small molecule inhibitors.

The overlooked chamber in coronavirus disease 2019

Coronavirus disease 2019 (COVID-19) causes a pandemic around the globe. Debilitating and even deadly complications have occurred to the millions. A recent study reported 31% of right ventricular dilation in the hospitalized COVID-19 patients, which is significantly associated with the mortality. Therefore, we sought to search for the lines of evidence in the literature that COVID-19 may contribute to right heart dysfunction. The relevant literature and data from PubMed, Embase, Cochrane Library databases, and Web of Science were searched using the MeSH terms including 'COVID-19', 'SARS-CoV-2', 'novel coronavirus pneumonia', 'novel coronavirus', 'right heart failure', 'right heart dysfunction', 'pulmonary hypertension', 'pulmonary embolism', and various combinations. The collected literature and data were sorted and summarized. Literature reports that angiotensin-converting enzyme 2 (ACE2) is the host receptor mediating the cell entry of severe acute respiratory syndrome coronavirus 2. Clinical and experimental evidence shows that loss of function of ACE2 aggravates pulmonary hypertension and gain of function of ACE2 exerts protection on cardiopulmonary circulation. Moreover, the patients with COVID-19 are more susceptible to pulmonary embolism and severe pneumonia-induced acute respiratory distress syndrome. Therefore, COVID-19 may cause right heart dysfunction by inducing pulmonary hypertension, pulmonary embolism, and acute respiratory distress syndrome. Particular attention should be paid to the function of the right heart, the overlooked chamber in COVID-19. Blood gas analysis, laboratory test of cardiac injury markers, physical examination, and echocardiography should be performed to identify right heart failure as early as possible. Once the right heart failure is confirmed, the therapeutic modalities following the guidelines of European Society of Cardiology should be employed to reduce mortality.

An innovative method for the selection of inhibitors of the viral spike-glycoprotein of the SARS-CoV

This paper has developed and described a detailed method for selecting inhibitors based on modified natural peptides for the SARS-CoV BJ01 spike-glycoprotein. The selection of inhibitors is carried out by increasing the affinity of the peptide to the active center of the protein. This paper also provides a step-by-step algorithm for analyzing the affinity of protein interactions and presents an analysis of energy interactions between the active center of a protein and the wild-type peptide interacting with it, taking into account modifications of the latter. A description of the software package that implements the presented algorithm is given on the website https://binomlabs.com/covid19.

The flexibility of ACE2 in the context of SARS-CoV-2 infection

The coronavirus disease 2019 (COVID-19) pandemic has swept over the world in the past months, causing significant loss of life and consequences to human health. Although numerous drug and vaccine development efforts are underway, there are many outstanding questions on the mechanism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral association to angiotensin-converting enzyme 2 (ACE2), its main host receptor, and host cell entry. Structural and biophysical studies indicate some degree of flexibility in the viral extracellular spike glycoprotein and at the receptor-binding domain (RBD)-receptor interface, suggesting a role in infection. Here, we perform explicitly solvated, all-atom, molecular dynamics simulations of the glycosylated, full-length, membrane-bound ACE2 receptor in both an apo and spike RBD-bound state to probe the intrinsic dynamics of the ACE2 receptor in the context of the cell surface. A large degree of fluctuation in the full-length structure is observed, indicating hinge bending motions at the linker region connecting the head to the transmembrane helix while still not disrupting the ACE2 homodimer or ACE2-RBD interfaces. This flexibility translates into an ensemble of ACE2 homodimer conformations that could sterically accommodate binding of the spike trimer to more than one ACE2 homodimer and suggests a mechanical contribution of the host receptor toward the large spike conformational changes required for cell fusion. This work presents further structural and functional insights into the role of ACE2 in viral infection that can potentially be exploited for the rational design of effective SARS-CoV-2 therapeutics.