Environmental control of Th17 differentiation.

Th17 cells participate in the control of extracellular bacteria and fungi, but dysregulated Th17 cell activity can result in immunopathology. Thus, the generation and the activity of Th17 cells should be tightly regulated, and simultaneously it should be able to respond to the challenges presented by a changing environment. In this viewpoint, we discuss some of the mechanisms by which microbes, dietary components and environmental toxins influence the Th17 response.