ACE2 and acute respiratory distress syndrome: According to the work done by Yumiko and colleagues, ACE2 knockout mice had showed a highly severe sickness in 3 separate models of ARDS: acid aspiration-induced ARDS, endotoxin-induced ARDS and peritoneal sepsis-induced ARDS, as compared to wild-type mice. ACE2 improved the clinical manifestations of lung damage in both wild as well as ACE2 knockout mice.61,63 This explains why ACE2 protects against lung injury.