Autophagy Regulates IL-23 Secretion and Innate T Cell Responses through Effects on IL-1 Secretion

Autophagy controls IL-1 beta secretion by regulating inflammasome activation and by targeting pro-IL-1 beta for degradation. In this article, we show that inhibition of autophagy, either with the PI3K inhibitors 3-methyladenine, wortmannin, and LY294002 or with small interfering RNA against autophagy proteins augmented the secretion of IL-23 by human and mouse macrophages and dendritic cells in response to specific TLR agonists. This process occurred at the transcriptional level and was dependent on reactive oxygen species and IL-1R signaling; it was abrogated with an IL-1R antagonist or with IL-1-neutralizing Abs, whereas treatment with either rIL-1 alpha or IL-1 beta induced IL-23 secretion. Dendritic cells treated with LPS and 3-methyladenine secreted enhanced levels of both IL-1 beta and IL-23, and supernatants from these cells stimulated the innate secretion of IL-17, IFN-gamma, and IL-22 by gamma delta T cells. These data demonstrate that autophagy has a potentially pivotal role to play in the induction and regulation of inflammatory responses by innate immune cells, largely driven by IL-1 and its consequential effects on IL-23 secretion. The Journal of Immunology, 2012, 189: 4144-4153.