Abstract A080: Balance of commensal bacteria specific Th17 and RORγt+ Treg cells in intestinal homeostasis and inflammation

A number of Helicobacter species, including  Helicobacter hepaticus , have been isolated as the etiological agents of ulcerative inflammatory bowel disease and cancer in their respective hosts.  H. hepaticus  induces severe Th17-Th1 mediated colitis in a number of immuno-compromised mouse strains, but does not usually cause disease in most wild-type mouse strains. However, how the inflammatory response is carefully contained to be harmless under homeostatic conditions and how perturbations lead to pathogenicity remain elusive questions. To understand this, we developed new research tools, including TCR transgenic mice, as well as MHCII tetramers to interrogate the regulation of  H. hepaticus -specific CD4 + T cell function. Interestingly, in contrast to Segmented Filamentous Bacteria (SFB), which induces Th17 cells in the small intestinal lamina propria (SILP) of both IL10 +/− and IL-10 −/− mice,  H. hepaticus  mainly induces RORgt + Treg cells in the large intestinal lamina propria (LILP) of IL-10-sufficient mice, but induces a Th17-Th1 response in the absence of IL-10. We propose that the balance between self/commensal antigen-induced RORgt + Treg and Th17 cells may be a general strategy to control autoimmune inflammation. Note: This abstract was not presented at the conference. Citation Format: Mo Xu, Yi Yang, Maria Pokrovskii, Carolina Galan, Dan R. Littman. Balance of commensal bacteria specific Th17 and RORγt + Treg cells in intestinal homeostasis and inflammation [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr A080.