Fig. 2
From: Identifying pathophysiological bases of disease in COVID-19
The effect of ACE2 expression levels on COVID-19 disease and severity. Age, genetics, and different comorbidities affect the pre-infection ACE2 expression levels in a subset of individuals (left), rendering them susceptible to severe forms of disease. During infection (right), upon interaction of SARS-CoV-2 S protein with ACE2 and TMPRSS2, ACE2 levels are downregulated. Those individuals with low pre-infection ACE2 levels reach a threshold critical value corresponding to the onset of severe symptomathologies due to RAAS imbalance