ACE2 and acute respiratory distress syndrome: The initial step in the development of SARS-CoV-2-induced ARDS is the interactions between the SARS-CoV-2 spike (S) protein and angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2) of alveolar type II cells (AT2) (Figure 1) [3].