Abstract
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.
Highlights
Accepted: 6 August 2021In December 2019 in Wuhan, China, a novel coronavirus was detected: the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)
Microarray and RNA-sequencing expression data showed that the expression of Angiotensin-Converting Enzyme 2 (ACE2) in pancreatic islets was significantly (p ≤ 0.05) increased in diabetic patients compared to non-diabetic patients and that transmembrane protease serine 2 (TMPRSS2) expression was positively correlated with hemoglubin A1c (HbA1c) levels (p = 0.04) [83]
We reviewed some significant aspects of the SARS-CoV-2 invasion that are proving to be complex and difficult to tackle and dwelt on how several factors may interfere with the virus main host cell receptor, ACE2, which is intrinsically related to the damage that arises upon infection
Summary
In December 2019 in Wuhan, China, a novel coronavirus was detected: the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) This virus was responsible for the Coronavirus Disease 2019 (COVID-19) and has spread across the globe, being classified as a global pandemic in March 2020 [1]. Microorganisms 2021, 9, 1692 indicating that SARS-CoV-2 may infect multiple organs, explaining the positive detection of SARS-CoV-2 in patients’ faeces and urine [16,17,18,19]. This comprehensive review describes the current knowledge regarding the correlation between the levels of expression of the ACE2 in various organs and poor outcomes in COVID-19 patients. Two were duplicated and 23 were excluded for not addressing the topic or not fitting the question
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