TMPRSS2 and infection: Direct infection of endothelium might be such a factor.62 ACE2 is detected by immunohistochemistry on vascular endothelium66; however, single-cell sequencing does not confirm ACE2 or TMPRSS2 expression in endothelium.79 Ex vivo experiments on explants do not demonstrate endothelial infection.80 SARS-CoV-2 infection causes downregulation of ACE2, a negative regulator of angiotensin II.