TMPRSS2 and chronic obstructive pulmonary disease: Recent work has shown that primary bronchial epithelial cells from COPD patients are much more susceptible to SARS-CoV-2 infection than healthy individuals, due to increased expression of SARS-CoV-2 entry receptors such as TMPRSS2 and cathepsin B, and that COPD cells had much higher pro-inflammatory cytokine responses and blunted type I IFN responses [54].