P926 Blautia Obeum Aggravates Colitis in a Murine Model

Abstract Background Blautia is a genus of anaerobic bacteria known as having probiotic properties in several studies. The aim of this study was to investigate the role of Blautia obeum in inflammatory bowel disease which has not yet been elucidated. Methods To assess the role of B. obeum, 7 weeks-old C57BL/6 mice were treated with 3% dextran sulfate sodium (DSS) for 5 days with or without oral administration of B. obeum simultaneously in the first experiment. Comparing with negative (only phosphate buffered saline) and positive (without intake of microbiome) controls, prior daily administration of B. obeum (day 0 to 7) and subsequent administration of DSS (day 7 to 15) were done in the second experiment. Body weight was evaluated daily in those acute colitis models. Macroscopic analysis and histological evaluation for inflammatory activity were evaluated after sacrifice. Moreover, inflammatory cytokines such as interleukin (IL), tumor necrosis factor alpha (TNF-α), and interferon gamma (IFN-γ) in the colonic lamina propria mononuclear cells were measured by quantitative real-time polymerase chain reaction. Fecal samples were collected from all subjects during experiments, and the influences on gut microbiota were analyzed by 16S rRNA gene-pyrosequencing. Results B. obeum aggravated colitis assessed by body weight loss. Histologic severity was higher in mice treated with B. obeum than in controls. IL-17, IFN-γ, and TNF-α were increased in mice treated with B. obeum, compared with controls. A significantly lower richness (P<0.05) and difference in community composition (P=0.009) of metagenomic species was seen in mice treated by B. obeum, compared with controls. To confirm the direct role of B. obeum in a murine colitis, we treated antibiotics for 7 days before the administration of B. obeum. In this experiment. B. obeum aggravated colitis assessed by body weight reduction and colon shortening as well as histologic severity. Conclusion B. obeum aggravates colitis in mice. B. obeum can be an organism that is associated with the pathogenesis in inflammatory bowel disease.