Regulatory T cells (Tregs) exert their immunosuppressive activity through several immunoregulatory mechanisms, including the production of anti-inflammatory cytokines such as IL-10. Although several studies suggest a role for Tregs in modulating crescentic GN, the underlying mechanisms are not well understood. Here, using IL-10 reporter mice, we detected IL-10-producing Foxp3(+) T cells in the kidney, blood, and secondary lymphoid tissue in a mouse model of crescentic GN. Specific inactivation of Il10 in Foxp3(+) Tregs eliminated the ability of these cells to suppress renal and systemic production of IFNγ and IL-17; these IL-10-deficient Tregs lost their capacity to attenuate renal tissue injury. These data highlight the suppressive functions of Tregs in crescentic GN and suggest the importance of Treg-derived IL-10 in ameliorating disease severity and in modulating both the Th1 and most notably Th17 immune response.
