| Summary: | COVID-19 is spreading globally with the angiotensin converting enzyme (ACE)-2 serving as the entry point of SARS-CoV-2 virus. This raised concerns how ACE2 and the Renin-Angiotensin (Ang)-System (RAS) are to be dealt with given their roles in hypertension and their involvement in COVID-19's morbidity and mortality. Specifically, increased ACE2 expression in response to treatment with ACE inhibitors (ACEi) and Ang II receptor blockers (ARBs) might theoretically increase COVID-19 risk by increasing SARS-CoV-2 binding sites. However, ACE2 is part of the protective counter-regulatory ACE2-Ang1-7-MasR axis, which opposes the classical ACE-AngII-AT1R regulatory axis. We used Gitelman's and Bartter's syndromes (GS/BS) patients, rare genetic tubulopathies that have endogenously increased levels of ACE2, to explore these issues. Specifically, 128 genetically confirmed GS/BS patients, living in Lombardia, Emilia Romagna and Veneto, the Northern Italy hot spots for COVID-19, were surveyed via telephone survey regarding COVID-19. The survey found no COVID-19 infection and absence of COVID-19 symptoms in any patient. Comparison analysis with the prevalence of COVID-19 in those regions showed statistical significance (p < 0.01). The results of the study strongly suggest that increased ACE2 does not increase risk of COVID-19 and that ACEi and ARBs by blocking excessive AT1R-mediated Ang II activation might favor the increase of ACE2-derived Ang 1-7. GS/BS patients' increased ACE2 and Ang 1-7 levels and their characteristic chronic metabolic alkalosis suggest a mechanism similar to that of chloroquine/hydroxychloroquine effect on ACE2 glycosylation alteration with resulting SARS-COV-2 binding inhibition and blockage/inhibition of viral entry. Studies from our laboratory are ongoing to explore GS/BS ACE2 glycosylation and other potential beneficial effects of BS/GS. Importantly, the absence of frank COVID-19 or of COVID-19 symptoms in the BS/GS patients cohort, given no direct ascertainment of COVID-19 status, suggest that elevated ACE2 levels as found in GS/BS patients at a minimum render COVID-19 infection asymptomatic and thus that COVID-19 symptoms are driven by ACE2 levels.
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