P098 Receptor-interacting protein 1 kinase inhibition therapeutically ameliorates experimental T-cell-dependent colitis in mice

Background Inflammatory bowel disease (IBD) is a multifactorial disorder characterised by chronic and relapsing intestinal inflammation. Receptor-interacting protein 1 (RIP1) kinase activity is emerging as a driver of pro-inflammatory cytokine production and cell death and has been implicated in multiple inflammatory diseases including IBD. To this end, recent work has shown that RIP1 kinase inhibition reduces the spontaneous production of cytokines from human ulcerative colitis (UC) and Crohn’s disease explants. Methods The aim of this study was to investigate the anti-inflammatory effect of a highly selective inhibitor of RIP1 kinase activity (GSK547A) in the mouse T-cell transfer model of colitis; a model that shares many features with human IBD. All animal studies were ethically reviewed and carried out in accordance with Animals (Scientific Procedures) Act 1986 and the GSK Policy on the Care, Welfare and Treatment of Animals. Chronic colitis was achieved by transferring CD4+CD45RBhigh T cells into immunodeficient female SCID mice (6/8 weeks old). After confirming the development of pathology using endoscopy and MRI, animals were treated therapeutically with the RIP1 inhibitor GSK547A (50 mg/kg twice a day PO) or vehicle (0.5% hydroxypropyl methylcellulose in water). The severity of colitis was measured 5 weeks after cell transfer both macro- and microscopically. Mucosal damage by endoscopy was also assessed. RT-PCR and MSD analysis were performed to detect colon cytokine/chemokine and calprotectin levels. SAA in the plasma was measured using ELISA. Results We found that treatment with GSK547 significantly ameliorated experimental T-cell-dependent colitis in mice. GSK547A-treated mice displayed decreased weight loss, colon density (ratio weight/length), macroscopic disease activity index, colon thickness compared with vehicle-treated animals. Mucosal damage, assessed by endoscopy and histopathology, was also reduced following treatment with RIP1 kinase inhibitor. In addition, GSK547A reduced the expression of cytokines in the colon (TNF-α, IL-17A, INF-γ, IL-6 and MCP-1), both at a protein and RNA level. Relevant translational biomarkers such as SAA in plasma and RNA calprotectin in the colon were also decreased in the GSK547A treated group when compared with vehicle. Conclusion Our results suggest that RIP1K inhibition is a strong protective factor with anti-inflammatory potential in the progression of chronic colitis, when applied to the translationally relevant T-cell transfer model of colitis. These findings suggest the potential application in the management of inflammatory bowel disease and support the ongoing clinical program evaluating the effect of RIP1 kinase inhibition in UC patients.