The IL-23/IL-17 and IL-12/IFN-γ cytokine pathways have a role in chronic autoimmunity, which is considered mainly a dysfunction of adaptive immunity. The extent to which they contribute to innate immunity is, however, unknown. We used a mouse model of acute kidney ischemia-reperfusion injury (IRI) to test the hypothesis that early production of IL-23 and IL-12 following IRI activates downstream IL-17 and IFN-γ signaling pathways and promotes kidney inflammation. Deficiency in IL-23, IL-17A, or IL-17 receptor (IL-17R) and mAb neutralization of CXCR2, the p19 subunit of IL-23, or IL-17A attenuated neutrophil infiltration in acute kidney IRI in mice. We further demonstrate that IL-17A produced by GR-1+ neutrophils was critical for kidney IRI in mice. Activation of the IL-12/IFN-γ pathway and NKT cells by administering α-galactosylceramide–primed bone marrow–derived DCs increased IFN-γ production following moderate IRI in WT mice but did not exacerbate injury or enhance IFN-γ production in either Il17a–/– or Il17r–/– mice, which suggested that IL-17 signaling was proximal to IFN-γ signaling. This was confirmed by the finding that IFN-γ administration reversed the protection seen in Il17a–/– mice subjected to IRI, whereas IL-17A failed to reverse protection in Ifng–/– mice. These results demonstrate that the innate immune component of kidney IRI requires dual activation of the IL-12/IFN-γ and IL-23/IL-17 signaling pathways and that neutrophil production of IL-17A is upstream of IL-12/IFN-γ. These mechanisms might contribute to reperfusion injury in other organs.
Li Li, Liping Huang, Amy L. Vergis, Hong Ye, Amandeep Bajwa, Vivek Narayan, Robert M. Strieter, Diane L. Rosin, Mark D. Okusa
Both IL-12/IFN-γ and IL-23/IL-17 pathways are necessary in activated NKT cell–promoted kidney IRI inflammation.