TYK2 and COVID-19: Thus, to gain further insight into COVID-19 pathophysiology, we obtained PBC samples of controls and COVID-19 patients on admission to the hospital to analyze the expression of selected genes that are part of the known ACE2-based port of entry of SARS-CoV-2 into cells (ADAM17, ACE2, TMPRSS2 and IFITM3), together with other genes encoding cytokines expressed in blood cells (IL6, IL7, IFNG, IFNE, CXCL8, CXCL9, CXCL10, CXCL11), or previously reported to be related to COVID-19 severity (CCR2, TYK2, EDN1) [26,27].