A19 BACTERIAL PROTEASES INCREASE SENSITIVITY TO DIETARY ANTIGEN THROUGH PAR-2 SIGNALING. (1st March 2018)

• Record Type: Journal Article
• Authors: CAMINERO FERNANDEZ, A; McCarville, J; Galipeau, H J; Deraison, C; BERNIER, S; Murray, J a; Coombes, B K; Ruf, w; Casqueiro Blanco, J; Surette, M; Vergnolle, N; Verdu, E
• Is Part Of: Journal of the Canadian Association of Gastroenterology. Volume 1(2018)Supplement 2
• Page Start: 31
• Page End: 32
• Publication Date: 2018-03-01
• Subjects: Gastroenterology -- Periodicals; 616.33005
• DOI: 10.1093/jcag/gwy009.019
• Languages: English
• ISSNs: 2515-2084

Abstract

Abstract: Background: Microbial-dietary-host interactions are generally homeostatic but when dysfunctional, can incite food sensitivities such as celiac disease in genetically predisposed people. However, the specific pathways involved and sequence of events remain poorly understood. We have previously shown that bacterial metabolism of the common dietary antigen, gluten, affects its immunogenicity. Aims: Here we tested whether microbial proteases able to degrade gluten also activate innate immune mechanisms important for the development of food sensitivity. Methods: Clean SPF (Altered Schaedler flora colonized) C57BL/6 and NOD-DQ8 mice were colonized with wild-type (WT) Pseudomonas aeruginosa strain PA14 or its lasB mutant derivative (lacking elastase activity) and then sensitized and challenged with gluten. In order to study bacterial-host specific interactions, germ-free mice were also colonized with both P. aeruginosa strains (WT and lasB ) and placed on a gluten-free diet. Finally, SPF protease-resistant PAR2 mutant mice were colonized with WT and lasB . Small intestinal microbial composition, proteolytic activity, intraepithelial lymphocyte (IEL) counts, expression of specific innate genes, bacterial infiltration in the mucus layer and villus-to-crypt (V/C) ratios were measured in all mice. Results: P. aeruginosa expressing elastase, previously shown to participate in the intestinal metabolism of gluten peptides, produced a PAR-2 pro-inflammatory response associated with increases in IELs in clean-SPF and GF C57BL/6 mice, independently of gluten treatment. This response was characterized by an increased expression of certain genes related to IEL induction and cytotoxicity, barrier function, and autoimmunity including Ifnγ, Tnfα, Tgfβ, Il6, IL17, IL22 and Fasl in the IEL compartment. Moreover, the presence of P. aeruginosa expressing elastase also led to shifts in the microbiota composition and bacterial encroachment to the mucosa. In NOD-DQ8 mice, a mouse model of gluten sensitivity, P. aeruginosa expressing elastase enhanced gluten immunopathology characterized by a reduction in V/C ratios. Conclusions: Bacterial protease, previously shown to degrade gluten peptides, can directly impact the host immune response through activation of PAR-2 and contribute to small intestinal pathology. This pathway could be targeted therapeutically in genetically susceptible individuals to prevent celiac disease. Funding Agencies: CAG, CIHRFarncombe Institute Postdoctoral Fellowship