ACE2 and acute respiratory distress syndrome: Lin and collaborators [19] demonstrated, using a mouse model, that PM2.5-induced ALI is regulated by the Renin-Angiotensin System (RAS) and the Angiotensin-Converting Enzyme II/angiotensin 1-7/Mas receptor (ACE2/Ang(1-7)/Mas) axis has a crucial role in the pathogenesis of lung injury.