IL-17A Production by Renal γδ T Cells Promotes Kidney Injury in Crescentic GN

The Th17 immune response appears to contribute to the pathogenesis of human and experimental crescentic GN, but the cell types that produce IL-17A in the kidney, the mechanisms involved in its induction, and the IL-17A-mediated effector functions that promote renal tissue injury are incompletely understood. Here, using a murine model of crescentic GN, we found that CD4(+) T cells, gamma delta T cells, and a population of CD3(+)CD4(-)CD8(-)gamma delta T cell receptor(-)NK1.1(-) T cells all produce IL-17A in the kidney. A time course analysis identified gamma delta T cells as a major source of IL-17A in the early phase of disease, before the first CD+ Th17 cells arrived. The production of IL-17A by renal gamma delta T cells depended on IL-23p19 signaling and retinoic acid-related orphan receptor-gamma t but not on IL-1 beta or IL-6. In addition, depletion of dendritic cells, which produce IL-23 in the kidney, reduced IL-17A production by renal gamma delta T cells. Furthermore, the lack of IL-17A production in gamma delta T cells, as well as the absence of all gamma delta T cells, reduced neutrophil recruitment into the kidney and ameliorated renal injury. Taken together, these data suggest that gamma delta T cells produce IL-17A in the kidney, induced by IL-23, promoting neutrophil recruitment, and contributing to the immunopathogenesis of crescentic GN.