Renin Angiotensin Axis, Angiotensin Converting Enzyme 2 and Coronavirus

Abstract

The renin-angiotensin-aldosterone system (RAAS) is the main plasma volume regulator, which maintains cardiovascular and hydrosaline homeostasis. In the classical pathway, the angiotensin converting enzyme (ACE) generates Angiotensin II (AngII), which is powerfully inflammatory and vasoconstrictive. This classical pathway is also regulated by ACE2, which converts AngI to Ang 1-9, and degrades AngII to Ang 1-7, whose vasodilatory and anti-inflammatory functions balance out the effects of AngII. ACE2 has been associated with the pathogenesis of respiratory infections such as RSV and severe acute respiratory syndrome coronavirus (SARS-CoV and SARS-CoV-2). Recent studies have shown that ACE2 corresponds to the main SARS-CoV-2 receptor, which together with other receptors such as the TMPRSS2, allows the virus to attach, fuse, and enter the host cell. These studies have shown that in animals infected with coronavirus there is a drop in tissue concentration of ACE2 and Ang 1-7, leading to overexpression of AngII and its vasoconstrictive and inflammatory effects. Experiments with recombinant ACE2 have shown a protective effect against overexpression of RAAS in coronavirus-infected animals, which is similar to that demonstrated with the use of AngII receptor blockers (AT1). Evidence on the protective role of ACE2 seems to support the recommendations re garding not discontinuing these drugs in COVID-19 infection. In this article, we present the current knowledge about the role of RAAS in coronavirus infection, based on physiopathological concepts, molecular bases, and experimental and clinical evidence.