IL6R and COVID-19: Since soluble IL-6R is abnormally elevated in the plasma of COVID-19 patients, presumably secondary to cleavage from the cells surface by TACE/ADAM17 upon SARS-CoV-2 infection and the inflammatory response associated with COVID-19 [29], IL-6 can activate most cells, including endothelial cells, which do not express endogenous IL-6R but can be activated by the complex of soluble IL-6R and IL-6 [164,165].