Microbiota in autoimmunity and tolerance

The composition of a host's intestinal microbiota directs the type of mucosal and systemic immune responses by affecting the proportion and number of functionally distinct T cell subsets. In particular, the microbiota composition affects the differentiation of intestinal Th17 cells and Foxp3+ regulatory T cells, both of which play critical roles in maintaining mucosal barrier functions and in controlling immunological homeostasis. In this review, we discuss the recent advances in our understanding of how the intestinal microbiota affects T cell differentiation and host susceptibility to autoimmune disease.

► Intestinal microbiota affects T cell differentiation and thereby host susceptibility to autoimmune disease.
► SFB induce the accumulation of Th17 cells in the small intestinal lamina propria.
► Intestinal Th17 cells induced by SFB affect the local and systemic autoimmune and inflammatory diseases.
► The number of colonic Treg cells is affected by the microbiota, particularly by Clostridium species.
► Treg cells induced by Clostridium species affect autoimmunity and tolerance.