Irritable Bowel Syndrome (IBS) is a common gastrointestinal disorder that affects 15-20% of the population in the U.S. The incidence of IBS in China is increasing at an alarming rate. Many challenging issues complicate data interpretation in gut microbiome studies in IBS patients. No single unifying cause has been identified, but recent evidence suggests the involvement of the gut microbiota. Diet has a profound influence on the gut microbial composition and it is unclear whether patients with IBS who eat a vegetarian diet have similar alterations in gut microbial composition as those who consume a meal diet rich in fat and protein. This study investigates the effect of diet and racial factors on the gut microbiota of patients with IBS and aims to fingerprint the microbial composition of a subpopulation of IBS patients who may respond to antibiotic (rifaximin) treatment. The project seeks to determine the differences in gut microbiota between healthy subjects and two groups of patients with IBS consuming either a meat diet or a vegetarian diet. Parallel studies will be conducted in Beijing and Ann Arbor to evaluate the impacts of race and environmental differences on the development of gut dysbiosis in IBS and the clinical response to rifaximin treatment. The study team anticipate only patients showing gut dysbiosis, independent of diet, will respond symptomatically, with normalization of gut mucosal physiology and amelioration of inflammatory tone. This proposal will be the first clinical IBS study with well-phenotyped cohorts to determine the effect of diet and racial factors on gut dysbiosis in IBS. This information is critical for identifying patients who may respond to antibiotic treatment. The key feature of this study of IBS in humans include distinct racial populations and dietary habits. Findings from this seed project will provide unique and novel information to develop hypothesis-driven studies for subsequent extramural funding.

• 119 IBS and 91 healthy controls were enrolled in the study, with 155 completed.
• 1 PKUHSC PhD student received extensive training in microbiome research at Michigan Medicine mentored by Dr. Owyang.
• 58 IBS stool samples and 30 controls stool samples were shipped from PKUHSC to Michigan Medicine for microbiome analyses.
• The results showed a great proportion female patients and meat eaters in the IBS subjects compared to healthy controls. Meat eaters and male gender have a greater predictable relationship related to maximum tolerated rectal sensation.