Awardees

Benjamin Sallis  |  McCormick Research Group  |  F30 Award

Project Summary/Abstract: Ulcerative Colitis (UC) is a devastating disease characterized by recurring episodic inflammation of the colonic mucosa that imposes a significant health and monetary burden on the developed world. Currently a significant portion of patients with UC are treated with TNFα inhibiting antibodies. Such treatments are burdensome on the healthcare system financially and pose the risk of significant side effects and frequently lead to the development of anti-drug antibodies, and consequent infusion reactions, and treatment failure. Consequently, researching novel cost effective, low risk approaches for treating ulcerative colitis should be of high priority. One approach is to leverage the microbiome to restore and maintain a non-inflammatory state in the colon, instead of targeting the systemic immune system. Dysbiosis is a hallmark of ulcerative colitis and leads to consequent dysregulation of local host immune pathways such as neutrophil transmigration through the intestinal epithelium, which has been shown to be instrumental in the initiation of mucosal inflammation in UC and its perpetuation through disruption of the intestinal barrier. The dysbiotic microbes in the colon of patients with UC have been shown to decrease P-glycoprotein (P-gp) expression. Under homeostatic conditions P-gp inhibits neutrophil transmigration through maintenance of a transepithelial gradient of endocannabinoids, thereby preventing aberrant inflammation. Thus, increases in intestinal epithelial cell (IEC) P-gp expression promises to limit inflammation in UC by preventing neutrophil transcytosis. To this end we must understand the mechanisms by which intestinal P-gp is regulated. While previous work has shown the microbiome dependence of intestinal P-gp expression, the specific microbial signals and the underlying metabolic networks have not yet been explored. In this proposal I will design an optimized microbial consortium to induce P-gp in IECs and dampen colonic inflammation in ulcerative colitis. Additionally, I study the microbial signals and underlying microbial dynamics that induces P-gp. In Aim 1 I will determine candidate bacterial species with the potential to regulate IEC P-gp. I will then use these strains to design and optimize a commensal consortium to induce P-gp when transferred into mice. The use of such a consortium as a potential bacteriotherapeutic for dampening intestinal inflammation will be studied using murine inflammatory bowel disease models. In Aim 2 I will study the mechanisms by which microbes communicate with each other and the host epithelium to induce P-gp. I will use a targeted and an unbiased approach to determine the bacterial signals and metabolites that upregulate P-gp and study the interactions between bacterial species that encourage P-gp induction on IECs. Overall, this study will provide insight into how the human microbiome regulates neutrophil transmigration and consequently intestinal inflammation. The design of the commensal consortium will serve as a first step in the development of a bacteriotherapeutic for treatment of ulcerative colitis.