CTSG and inflammatory bowel disease: Previous research has shown that increased proteolytic activity in IBD is often due to host proteases, such as neutrophil elastase, cathepsin G, and thrombin, which are released by infiltrating immune cells or the mucosa.8,9,77 Despite this, the role of bacterial proteases in IBD is being established,7 and the specific mechanisms underlying their colitogenic effects have received insufficient attention.