TMPRSS2 and infection: Although it has been confirmed that T lymphocytes in blood could be infected by SARS-CoV-2 in an ACE22/TMPRSS2-independent manner and the infection of T cells is likely to induce cell apoptosis in mitochondria ROS-HIF-1a-dependent pathways (47), little is known about the imbalance in T cell homeostasis and its mechanisms in intestinal barriers loss during SARS-CoV-2 infection.