ACE2 and endothelial dysfunction: ACE2 and RAS signaling, as a possible link between the pre-existing endothelial dysfunction and SARS-CoV-2 induced endothelial injury in COVID-19 associated mortality. Key roles of endothelial cell-expressed cell adhesion molecules including CD209L/L-SIGN and CD209/DC-SIGN in SARS-CoV-2 infection.