Inflammatory bowel diseases (IBD) are associated with berrant mucosal immune responses to the enteric microflora. Innate immunity drives the active flares of disease while adaptive immune responses are thought to maintain the chronically inflamed state. While IBD has generally been associated with elevated immune responses to gut bacteria, the recent findings that IBD patients have impaired levels of innate immunity suggest that, in fact, at least some incidence of IBD may in fact result from an underlying innate immune deficiency. Thus, mechanistically dissecting how alterations in innate immunity can eventuate in chronic inflammation should help understand the pathophysiology of IBD. The bacterial protein flagellin, the monomeric subunit of flagella, is a dominant innate immune activator of intestinal epithelial cells. Thus, experimental study of the flagellin receptor, toll-like receptor 5 (TLR5), may provide mechanistic insights into how alterations in innate immunity can result in IBD. In accordance, we have recently observed that TLR5-KO mice develop spontaneous colitis. Such colitis is associated with alterations in gut microflora and appears to be dependent upon both innate and adaptive immunity. Thus, we hypothesize that TLR5 plays an essential role in """"""""managing"""""""" the commensal microflora and that loss of TLR5 renders mice unable to properly manage their commensal microflora, resulting in chronic activation of other innate immune signaling pathways and development of """"""""colitogenic"""""""" T-cells. Thus we propose to 1) Determine how loss of TLR5 affects immune cells and examine their role in TLR5KO colitis and 2) Define how loss of TLR5 affects the enteric microbiota and the role such changes play in driving colitis.

Public Health Relevance

Engineered deletion toll-like receptor 5 (TLR5), in mice, results in pontaneous colitis. This project seeks to define the pathophysiologic mechanisms that underlie such colitis. We expect this information will prove insightful toward understanding the pathogenesis of Crohn's disease and ulcerative colitis, collectively referred to as inflammatory bowel disease.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Project (R01)
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Special Emphasis Panel (ZRG1-DKUS-G (08))
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Grey, Michael J
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Georgia State University
Other Domestic Higher Education
United States
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Etienne-Mesmin, Lucie; Chassaing, Benoit; Adekunle, Oluwaseyi et al. (2018) Toxin-positive Clostridium difficile latently infect mouse colonies and protect against highly pathogenic C. difficile. Gut 67:860-871
Zou, Jun; Chassaing, Benoit; Singh, Vishal et al. (2018) Fiber-Mediated Nourishment of Gut Microbiota Protects against Diet-Induced Obesity by Restoring IL-22-Mediated Colonic Health. Cell Host Microbe 23:41-53.e4
Fields, Christopher T; Chassaing, Benoit; Castillo-Ruiz, Alexandra et al. (2018) Effects of gut-derived endotoxin on anxiety-like and repetitive behaviors in male and female mice. Biol Sex Differ 9:7
Singh, Vishal; Yeoh, Beng San; Chassaing, Benoit et al. (2018) Dysregulated Microbial Fermentation of Soluble Fiber Induces Cholestatic Liver Cancer. Cell 175:679-694.e22
Fields, Christopher T; Chassaing, Benoit; Paul, Matthew J et al. (2018) Vasopressin deletion is associated with sex-specific shifts in the gut microbiome. Gut Microbes 9:13-25
Chassaing, Benoit; Van de Wiele, Tom; De Bodt, Jana et al. (2017) Dietary emulsifiers directly alter human microbiota composition and gene expression ex vivo potentiating intestinal inflammation. Gut 66:1414-1427
Etienne-Mesmin, Lucie; Chassaing, Benoit; Gewirtz, Andrew T (2017) Tryptophan: A gut microbiota-derived metabolites regulating inflammation. World J Gastrointest Pharmacol Ther 8:7-9
Viennois, Emilie; Merlin, Didier; Gewirtz, Andrew T et al. (2017) Dietary Emulsifier-Induced Low-Grade Inflammation Promotes Colon Carcinogenesis. Cancer Res 77:27-40
Etienne-Mesmin, Lucie; Chassaing, Benoit; Adekunle, Oluwaseyi et al. (2017) Genome Sequence of a Toxin-PositiveClostridium difficileStrain Isolated from Murine Feces. Genome Announc 5:
Chassaing, Benoit; Vijay-Kumar, Matam; Gewirtz, Andrew T (2017) How diet can impact gut microbiota to promote or endanger health. Curr Opin Gastroenterol 33:417-421

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