RORγt-dependent IL-17A-producing cells in the pathogenesis of intestinal inflammation

Abstract

The hypothesis of helper T(Th)1/Th2 cytokine balance proposed by Mosmann and Coffman is often invoked to explain the development of inflammatory diseases, including inflammatory bowel diseases (IBD). Recently, however, a newly identified class of Th cells - Th17 cells, which produce Th17 family cytokines - has been recognized as an essential subpopulation in the development of almost all kinds of human and animal inflammatory diseases, rather than Th1 and Th2 cells. A representative Th17 family cytokine, interleukin (IL)-17A, is produced by not only Th17 cells, but also by other types of cells, such as T-cell receptor γδ T cells, natural killer (NK) T cells, NK cells, myeloid cells, and innate lymphoid cells, which may also be critically involved in the initiation and persistence of IBD. Here we review recent advances in the study of such IL-17A-producing cells in the pathogenesis of IBD. © 2012 Society for Mucosal Immunology.