Tu1778 – The Gut Microbial Profile of Preclinical Crohn's Disease is Similar to that of Healthy Controls

without chemical, genetic, or immunologic manipulation.Six to nine SAMP and AKR mice were treated with a combination of antibiotics for one month before experiment to eliminate/ suppress gut bacteria.Similar number of SAMP mice and regular AKR mice without antibiotics pre-treatment were used as control.A total of three cycles of DSS (63 day) was used to induce chronic colitis.AOM/DSS model as previously described was used to induce colitis associated colon cancer.Endoscopy were performed in selected time points during the experiment and the day of sacrifice.Endoscopy score and disease activity index (DAI) were calculated in each time point.Colon weight, length and polyps were measured and quantified.Stereomicroscope and histology were performed in all of the mice.Results: Colorectal Inflammatory polyps and adenoma were only observed in chronic colitis model (DSS only) of SAMP1 mice.Interestingly, the majority of polyps were located in the distal colon close to the rectum.Colorectal tumor were formed in the AOM/DSS model of SAMP mice.Gut microbiome were significantly eliminated/suppressed in SAMP mice treated with combination of antibiotics.SAMP mice pre-treated with antibiotics have significantly lower number of polyps and adenoma in colitis model as well as lower number of colorectal tumor in AOM/ DSS model.DAI and overall condition of colon mucosa observed in stereomicroscope indicated the elimination/suppression of microbiome in SAMP mice has protected them from colitis induced mucosal damage.Conclusion: We have shown that inflammatory polyps and adenoma can form in the condition of chronic colitis in the Crohn's diseaselike mice.Those polyps and adenoma are tend to form in distal colon close to rectum.These results also demonstrate an essential role of microbiome in the development of colorectal cancer in Crohn's disease-like mice.Future direction include bacterial analysis and fecal microbiome transplant studies in those model. Tu1778