IL-17A produced by both γδ T and Th17 cells promotes renal fibrosis via RANTES-mediated leukocyte infiltration after renal obstruction.

IL-17A-producing T lymphocytes play a crucial role in inflammatory kidney diseases, but their role in renal fibrosis remains to be explored. Here, we demonstrated that up-regulation of IL-17A was associated with the development of obstructive kidney injury. The primary source of IL-17A production in obstructed kidneys was infiltrating γδ T lymphocytes and CD4(+) T cells. IL-17A-deficient mice were protected from myofibroblast activation and extracellular matrix deposition, leading to reduced kidney fibrosis in response to obstructive injury. Mechanistically, IL-17A deficiency suppressed the expression of the chemokine RANTES in infiltrated CD3(+) T cells and peritubular inflammation following renal obstruction. Administration of RANTES-neutralizing antibody significantly reduced the accumulation of T cells and macrophages, and of collagen deposition in obstructed kidneys. Taken together, our results indicate that IL-17A contributes significantly to the pathogenesis of renal fibrosis by regulating RANTES-mediated inflammatory cell infiltration.