A crucial role for interleukin (IL)-1 in the induction of IL-17–producing T cells that mediate autoimmune encephalomyelitis

PUBLISHED
It was recently demonstrated that interleukin (IL)-23?driven IL-17?producing (ThIL-17) T cells mediate inflammatory pathology in certain autoimmune diseases. We show that the induction of antigen-specific ThIL-17 cells, but not T helper (Th)1 or Th2 cells, by immunization with antigens and adjuvants is abrogated in IL-1 receptor type I?deficient (IL-1RI?/?) mice. Furthermore, the incidence of experimental autoimmune encephalomyelitis (EAE) was significantly lower in IL-1RI?/? compared with wild-type mice, and this correlated with a failure to induce autoantigen-specific ThIL-17 cells, whereas induction of Th1 and Th2 responses was not substantially different. However, EAE was induced in IL-1RI?/? mice by adoptive transfer of autoantigen-specific cells from wild-type mice with EAE. IL-23 alone did not induce IL-17 production by T cells from IL-1RI?/? mice, and IL-23?induced IL-17 production was substantially enhanced by IL-1? or IL-1?, even in the absence of T cell receptor stimulation. We demonstrate essential roles for phosphatidylinositol 3-kinase, nuclear factor ?B, and novel protein kinase C isoforms in IL-1? and IL-23?mediated IL-17 production. Tumor necrosis factor ? also synergized with IL-23 to enhance IL-17 production, and this was IL-1 dependent. Our findings demonstrate that IL-1 functions upstream of IL-17 to promote pathogenic ThIL-17 cells in EAE.
This work was supported by a Science Foundation Ireland Principal Investigator Award (no. 00/PI.I/B045 to K.H.G. Mills)