Etv5 promotes IL-10 production in Th2 cells

Abstract

Abstract The anti-inflammatory cytokine, IL-10, suppresses inflammatory responses at mucosal surfaces. Among T helper cell subsets, Th2 cells produce the highest concentrations. However, the transcription factors that regulate Il10 gene expression have not been completely defined. Etv5 is a member of the ETS transcription factor family that promotes production of IL-17 in Th17 cells and IL-9 in Th9 cells. To define the effects of Etv5 deficiency on cytokine expression in Th2 cells, T cells from CD4 specific Etv5 knockout (Etv5fl/flCD4-Cre+, termed Etv5 KO below) and littermate control (Etv5fl/fl CD4-Cre-, termed WT below) mice were differentiated under Th2 conditions. Etv5 was required for maximal IL-10 production and modestly repressed the Th2 cytokines IL-4, IL-5 and IL-13. In mice sensitized with Aspergilus fumigatus extract, IL-10 production in both BAL and lung was significantly reduced in Etv5 KO mice, consistent with in vitro data. Using ChIP and reporter assays, we showed that Etv5 directly binds to the Il10 locus, specifically at the CNS3 region. Etv5 promotes IL-10 production by recruiting IL-10 inducing transcription factors including Jun family members, IRF4 and E4BP4, and the binding of these factors to the Il10 locus, but not the expression of these factors, was decreased in the absence of Etv5. Ectopic GATA3 and E4BP4 expression recovers IL-10 production to wild type amounts, suggesting that Etv5 enhances the efficiency of function of these factors. Importantly, ectopic Etv5 expression in Etv5 KO Th2 cells restored binding of the factors to the Il10 locus. Thus, Etv5 promotes IL-10 production by enhancing the recruitment of IL-10 inducing transcription factors.