P107 The expression and regulation of Oncostatin M and its receptor in intestinal inflammation

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Abstract Background Intestinal homeostasis depends on the interplay between the gut microbiota, epithelium and immune cells. A novel role of Oncostatin M (OSM), a pro-inflammatory cytokine has recently been identified in mouse and human intestinal inflammation. Previous studies have shown OSM as a key driver of chronic inflammation in anti-TNF-α-refractory colitis. A single-nucleotide polymorphism in the human OSM genetic locus is strongly associated with risk of developing inflammatory bowel disease (IBD), thus, biological therapies targeting OSM could have therapeutic potential. Our project aims to explore the impact of OSM on intestinal barrier function in health and disease. Methods To evaluate the role of OSM in intestinal inflammation, we utilized a combination of in vitro and in vivo techniques. This included the generation of 3D intestinal organoids from mice and patients. Organoids were stimulated with a repertoire of different cytokines to determine the responsiveness of OSM receptor (OSMR) to different cytokine signals using a quantitative-PCR-based approach. For in vivo modelling of disease, the Helicobacter hepaticus colitis model was used, as it combines both immune and dysbiosis-driven aspects of disease. This allowed us to measure OSM and OSMR expression in response to inflammation and within specific organs and cell subsets. Furthermore, RNAscope in situ hybridisation was used to determine the localisation of OSM- and OSMR-expressing cells in inflamed mucosal tissue from colitic mice and IBD patients. Results RNAscope in situ hybridisation as well as gene expression analysis have shown that the OSM and OSMR were highly expressed in C57BL/6 mice upon induction of colitis in the H. hepaticus model of disease and in mucosal tissues of IBD patients. In addition, a plethora of pro-inflammatory cytokines were upregulated during colitis, with colitic mice showing increased tissue pathology. Furthermore, FACS analysis shows excessive immune cell infiltration in the spleen, colon and mesenteric lymph nodes of colitic mice. Conclusion Our preliminary results have shown that different gut-resident hematopoietic and non-hematopoietic cell types express OSM and OSMR and this expression was modulated by pro-inflammatory cytokines. We therefore hypothesis that OSM might drive distinct transcriptional responses in various gut-resident cell populations. Thus, differential targeting of the OSM receptor might be a potential therapeutic approach in IBD.