Stat3 Activation in Bacteria-Induced Murine Th17 Predominant Colonic Inflammation

Johns Hopkins University, Baltimore MD

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Abstract

[unreadable] DESCRIPTION (provided by applicant): Bacteroides fragilis is a common human commensal residing in the colon. B. fragilis enterotoxigenic (ETBF) class has been associated with inflammatory diarrheal disease, inflammatory bowel disease, and colorectal cancer. Recent murine model data has shown that chronic colonization with ETBF leads to a proliferative and proinflammatory response which can act as a co-factor in colon tumor initiation and promotion specifically in the multiple intestinal neoplasia (Min) model. Signal transducer and activator of transcription 3 (StatS) has both pro- and anti-inflammatory properties through activation by IL-6 and IL-10, respectively. Phosphorylated StatS is found in intestinal T cells from patients with chronic gut inflammation such as Crohn's disease most likely inhibiting apoptosis of T cells. It also is present in tumors where it functions as a tumor immune suppressor. Though important in chronic inflammation and tumors, its role has not been well studied. Specific Aim: To determine the effect of ETBF colonization on StatS in colonic tumor formation in Min mice and inflammation in a colitis-associated murine model. Mice (C57BL/6 and Min) Swks to 3-4mo of age will be used in the proposed experiments. The C57BL/6 mice will be used to demonstrate StatS activity in inflammation of the colitis-associated model while the Min mice will be used to analyze StatS activity in colonic tumor formation. After pre-treatment with antibiotics, under anesthesia, mice will be inoculated via oral gavage with ETBF, non-toxic B. fragilis, or placebo. Mice will be closely monitored in terms of clinical status (weight, activity, rectal bleeding, diarrhea) and sacrificed at various time points post inoculation (1 day to 3-4 months). Colon, cecum, and spleen will be harvested and used for pathology. Immunofluorescent staining using specific antibodies and Electophoretic mobility shift assay (EMSA) will also be used to demonstrate presence of phosphorylated StatS. Also tissue will be utilized for flow cytometry analysis of specific locations (epithelium, lamina propria) and cell types (lymphocytes, macrophages, neutrophils, etc) for StatS activity. This research will be relevant to public health in several ways. It will further define the potential role and pathway of a bacterium, ETBF, in inflammation and proliferation that could relate to disorders such as colon cancer and Inflammatory Bowel Disease. Furthermore it will establish a model in which therapeutic interventions could be attempted in hopes of treating such deadly prevalent diseases. [unreadable] [unreadable] [unreadable]