Unraveling the Identity of Active Serine Proteases in Inflammatory Bowel Diseases

Introduction Our team recently revealed that an upregulation in proteolytic activity is a central mechanism in the pathophysiology of Inflammatory Bowel Disease (IBD), such as Crohn's disease (CD) and ulcerative colitis (UC). Otherwise, the identity of proteases underlying this process remains elusive. Objective Identify active serine proteases in the colonic mucosa of IBD patients by using Activity‐Based Probes (ABP). Material and Methods Samples of colonic mucosa supernatants or tissue extracts were incubated with biotinylated ABPs designed to form covalent complexes with active serine proteases. ABP‐serine proteases complexes were then submitted to SDS‐PAGE to generate ABP proteomic profiles and LC‐MS/MS analysis to identify the active proteases. Results ABP proteomic profiles revealed that active proteases clustered in 4 main groups with mean MW of 27.8, 32.6, 35.4 and 71.5 kDa. Compared to control patients, there was a trend of upregulation for proteases with mean MW of 27.8 and 32.6 kDa in CD and UC, whereas a protease with 71.5 kDa was detected exclusively in UC. Preliminary LC‐MS/MS analysis of IBD samples identified up to 13 potential serine proteases (i.e. PRSS1/2, TPSAB1, DLD, PREP, etc) and 8 proteases from other clans (i.e. LTA4H, PARK7, etc). Conclusion The present study identified proteases not yet described as expressed in the colonic mucosa, as well as proteases derived from genes associated to IBD risk loci with unknown function in the gastrointestinal tract. This data will direct further studies aiming at establishing the relevance of these proteases in the pathophysiology of IBD. Support or Funding Information Agence Nationale de la Recherche (ANR) and European Research Council (ERC).