ACE2 and acute respiratory distress syndrome: Reasons for the diminished Ang II/Ang I ratio in ARDS may include the presence of a yet-to-be characterized endogenous ACE inhibitor, increased ACE2 activity (Krenn et al., 2020; Reindl-Schwaighofer et al., 2021), or increased activity of other, yet-to-be characterized proteases that process Ang II.