The role of microbiota in susceptibility to inflammatory bowel disease.

The cause of inflammatory bowel disease (IBD), including intestinal disorders characterized by chronic inflammation such as Crohn’s disease and ulcerative colitis, remains unclear. However, changes in the microbiota have been linked to IBD, including Crohn's disease and ulcerative colitis, as significant differences exist between the microbiota of IBD patients and healthy individuals. As western societies have developed, improvements in health and hygiene have altered human-microbe interactions through increased sanitation, antibiotic usage and vaccination. Concordantly, epidemiological studies have shown an alarming increase in the occurrence of immune mediated disorders, such as IBD. However, whether a change in microbiota composition precedes and contributes to onset of IBD or is a result of IBD remains to be determined. Marta Wlodarska and colleagues have previously shown that clinical levels of antibiotics will cause a shift in, but not complete ablation of the microbiota which results in a differential disease outcome by Salmonella Typhimurium infection. Her current research project expands on this work by investigating how antibiotic-induced fluctuations of the microbiota disrupt the homeostatic state of the intestinal immune system, potentially leading to increased susceptibility to IBD. Specifically, she is using clinical levels of antibiotics to shift the composition of the microbiota and evaluate how that affects the outcome and severity of C.rodentium-induced colitis. Additionally, her research should also provide an understanding of how changes in microbiota composition affect the homeostatic state of the mucosal immune system through intestinal epithelial cell-mediated cytokine secretion. Collectively, her work will increase the understanding of the interplay between the microbiota and immune responses as well as any associated impact on colitis. These issues are central to increasing our understanding of IBD in general, and may lead to the development of new diagnostic and therapeutic tools.