TMPRSS2 and cystic fibrosis: Other TLPs such as tryptase, matriptase, prostasin, human airway trypsin-like protease (HAT) and TMPRSS2 have been implicated in respiratory diseases such as cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD) and asthma (Akers et al., 2000; Bardou et al., 2016; Menou et al., 2017; Reihill et al., 2020; Carroll et al., 2021), as well as COVID-19 where TLPs are involved in the activation of the SARS-CoV-2 spike protein allowing cellular entry (Hoffmann et al., 2020).