Exploring the Demographics and Clinical Characteristics Related to the Expression of Angiotensin-Converting Enzyme 2, a Receptor of SARS-CoV-2

SARS-CoV-2 spike ectodomain targets α7 nicotinic acetylcholine receptors

Virus entry into animal cells is initiated by attachment to target macromolecules located on host cells. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) trimeric spike glycoprotein targets host angiotensin converting enzyme 2 to gain cellular access. The SARS-CoV-2 glycoprotein contains a neurotoxin-like region that has sequence similarities to the rabies virus and the HIV glycoproteins, as well as to snake neurotoxins, which interact with nicotinic acetylcholine receptor (nAChR) subtypes via this region. Using a peptide of the neurotoxin-like region of SARS-CoV-2 (SARS-CoV-2 glycoprotein peptide [SCoV2P]), we identified that this area moderately inhibits α3β2, α3β4, and α4β2 subtypes, while potentiating and inhibiting α7 nAChRs. These nAChR subtypes are found in target tissues including the nose, lung, central nervous system, and immune cells. Importantly, SCoV2P potentiates and inhibits ACh-induced α7 nAChR responses by an allosteric mechanism, with nicotine enhancing these effects. Live-cell confocal microscopy was used to confirm that SCoV2P interacts with α7 nAChRs in transfected neuronal-like N2a and human embryonic kidney 293 cells. The SARS-CoV-2 ectodomain functionally potentiates and inhibits the α7 subtype with nanomolar potency. Our functional findings identify that the α7 nAChR is a target for the SARS-CoV-2 glycoprotein, providing a new aspect to our understanding of SARS-CoV-2 and host cell interactions, in addition to disease pathogenesis.

Potential Role of Vitamin D, ACE2 and the Proteases as TMPRSS2 and Furin on SARS-CoV-2 Pathogenesis and COVID-19 Severity

BACKGROUND

COVID-19, the 21^st century pandemic disease caused by SARS-CoV-2, has shown a wide clinical spectrum ranging from asymptomatic to deadly serious pneumonia.

OBJECTIVE

In our study, the relationship between the pathogenesis and clinical severity of COVID-19 and vitamin D, ACE2, Furin and TMPRSS2 was investigated.

METHODS

Serum 25(OH)D, 1,25(OH)₂D and ACE2 protein were measured in 85 COVID-19 cases, divided into 5 groups, according to disease severity, from asymptomatic to severe and including a healthy control group. Expression levels of ACE2, VDR, TMPRSS2 and Furin mRNAs in PBMC were also measured. The relationship of the parameters within each group, the severity of the disease and the effect on the patients' fate were investigated.

RESULTS

Statistically significant differences were found between the severity of COVID-19 and all study parameters, except for serum 25(OH)D. A strong negative correlation was found between serum ACE2 protein, 1,25(OH)₂D, and ACE2 mRNA, and disease severity, length of hospital stay and death/survival rate. Vitamin D deficiency increased the death risk by 5.6-fold (95% CI 0.75-41.47), and the levels of 1,25(OH)₂D lower than 1 ng/mL increased the risk of death by 3.8-fold (95% CI 1.07-13.30).

CONCLUSION

This study suggests that vitamin D supplementation could be beneficial in the treatment and/or prevention of COVID-19.

Tobacco use as a well-recognized cause of severe COVID-19 manifestations

INTRODUCTION

The Coronavirus disease (COVID-19) infection is caused by the novel Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) primarily affecting the lungs. All tobacco-related illnesses including asthma, chronic obstructive pulmonary disease (COPD), and coronary artery disease are known to reduce the lung capacity and impair the immune system of the body and can greatly influence the ability to fight the novel coronavirus. The purpose of this state-of-the-art literature review is to summarize the evidence of the association of tobacco use with the severity of the COVID-19 manifestations.

METHOD

Articles describing the association of tobacco use with the severity of COVID-19 manifestations were searched on PubMed, MEDLINE, and Google. This review covers the relevant studies on the subject published from January 1, 2020 to September 10, 2020.

RESULTS

Tobacco use in all forms, whether smoking or chewing, is significantly associated with severe COVID-19 outcomes. Pre-existing comorbidities in tobacco users such as cardiovascular diseases, diabetes, respiratory diseases and hypertension were found to further aggravate the disease manifestations making the treatment of such COVID-19 patients more challenging due to their rapid clinical deterioration.

CONCLUSIONS

Current review indicates that nicotine exposure is linked to cardiopulmonary vulnerability to COVID-19 and tobacco use can be a potential risk factor for not only getting the viral infection but also its severe manifestations. The current pandemic provides a teachable moment to break the cycle of nicotine addiction and accelerate national tobacco control programs to achieve a tobacco-free world.

Possible Transmission Flow of SARS-CoV-2 Based on ACE2 Features

Angiotensin-converting enzyme 2 (ACE2) is the cellular receptor for the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) that is engendering the severe coronavirus disease 2019 (COVID-19) pandemic. The spike (S) protein receptor-binding domain (RBD) of SARS-CoV-2 binds to the three sub-domains viz. amino acids (aa) 22-42, aa 79-84, and aa 330-393 of ACE2 on human cells to initiate entry. It was reported earlier that the receptor utilization capacity of ACE2 proteins from different species, such as cats, chimpanzees, dogs, and cattle, are different. A comprehensive analysis of ACE2 receptors of nineteen species was carried out in this study, and the findings propose a possible SARS-CoV-2 transmission flow across these nineteen species.