CTSG and irritable bowel syndrome: Indeed, intestinal tissue from IBD patients shows an upregulation at the mRNA, protein and/or activity level of serine protease (e.g. cathepsin G, tryptase, thrombin, plasma kallikrein, chymotrypsin-like elastase 3A, plasmin and aminopeptidase B), cysteine protease, aspartate protease and metalloprotease families (Cleynen et al., 2011; Vergnolle, 2016; Denadai-Souza et al., 2018; Sola Tapias et al., 2020).