A188 Targeting Ripk2 to Treat Intestinal Inflammation Caused by Ship Deficiency

Abstract

Background Crohn’s disease (CD) is a form of inflammatory bowel disease characterized by chronic inflammation along the gastrointestinal tract. We have described the SHIP-/- mouse model of CD-like intestinal inflammation. SHIP-/- mice develop spontaneous ileal inflammation that is characterized by villus hyperplasia and disorganization, edema, immune cell infiltration, ulceration, loss of goblet cells, and muscle wall thickening. SHIP deficiency in people with CD has been associated with a more severe and treatment-refractory disease. Interestingly, NOD2 gene variants, which are the most profound genetic associations for CD, are also associated with a more severe CD phenotype. Muramyl dipeptide (MDP) is a molecular associated microbial pattern, which activates the NOD2 signalling pathway. Recently, SHIP has been reported to play a role in the NOD2 pathway by disrupting the downstream interaction between RIPK2 and XIAP required for NOD2-mediated NFκB activation and pro-inflammatory cytokine production. Aims Based on this, we hypothesized that SHIP deficiency contributes to inflammation in CD by increasing NOD2-mediated pro-inflammatory cytokine production. Moreover, RIPK2 inhibitors will block intestinal inflammation caused by SHIP deficiency by blocking RIPK2-XIAP interactions required for NOD2 signalling and resultant pro-inflammatory cytokine production. To test this hypothesis, my aim was to determine the effect of RIPK2 inhibitors on the development of spontaneous intestinal inflammation in SHIP-/- mice. Methods 6 week-old SHIP-/- mice (and SHIP+/+ mice controls) were treated with RIPK2 inhibitors, FCG806791773 or Z1210264067, by intra-pertioneal injections every other day for 2 weeks and compared to SHIP-/- mice treated with 2% DMSO in PBS, as a vehicle control. On Day 14, distal ilea were harvested and gross pathology was assessed. Cross-sections of the ilea were H&E stained to evaluate histological damage based on villi architecture, edema, immune cell infiltration, ulceration, goblet cell loss, and muscle wall thickening. Results As expected, SHIP+/+ mice did not have gut pathology and their healthy gut phenotype was not affected by RIPK2 inhibitors. SHIP-/- mice had ileal inflammation that was evident in gross pathology and in H&E-stained tissue sections. Importantly, SHIP-/- mice treated with RIPK2 inhibitors, FCG806791773 or Z1210264067, had reduced gross pathology compared to vehicle control-treated mice. Z1210264067 treated SHIP-/- mice also had significantly lower histological damage compared to vehicle control-treated SHIP-/- mice. Conclusions RIPK2 inhibitors reduced gross and histopathology in SHIP-/- mice suggesting that RIPK2 inhibitors may be an effective treatment for people with CD, and may be particularly effective in people with CD, who harbor NOD2 risk variants and/or have low SHIP activity. Funding Agencies CCC, CIHR