Research ArticleINTESTINAL BOWEL DISEASE

Helicobacter species are potent drivers of colonic T cell responses in homeostasis and inflammation

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Science Immunology  21 Jul 2017:
Vol. 2, Issue 13, eaal5068
DOI: 10.1126/sciimmunol.aal5068

Context is critical in IBD

The intestine hosts trillions of commensal microbes; however, exactly how these microbes contribute to a balanced immune response in the intestine is still being explored. Now, Chai et al. report that mucosal-associated Helicobacter species can trigger either regulatory T (Treg) or effector T (Teff) cell activation in mouse intestine, depending on context. T cells specific to the bacteria activated Treg cells in homeostatic conditions. In contrast, in a mouse model of colitis, Helicobacter species induced Teff cells. These data suggest that a pathobiont such as Helicobacter species may induce immune tolerance in homeostatic conditions but switch to contribute to pathogenesis in the presence of inflammation.