TMPRSS2 and COVID-19: Studies revealed that it may combat COVID-19 by inhibiting the SARS-CoV-2 S-protein-induced ACE2-dependent activation of NOX2, MCP-1, and ROS production.475,476 Baristaite et al. reported that treatment of A549 human lung epithelial cells with 17-β-estradiol reduced the cellular mRNA levels of ACE2 and TMPRSS2.477 This outcome may contribute to reduced SARS-CoV-2 infection of lung epithelial cells.