Project description:Dysregulated Th17 cell responses underlie multiple inflammatory and autoimmune diseases, including autoimmune uveitis and its animal model, EAU. However, clinical trials targeting IL-17A in uveitis were not successful. Here, we found that Th17 cells were regulated by their own signature cytokine, IL-17A. Loss of IL-17A in autopathogenic Th17 cells did not reduce their pathogenicity and instead elevated their expression of the Th17 cell cytokines GM-CSF and IL-17F. Mechanistic in vitro studies revealed a Th17 cell-intrinsic autocrine loop triggered by binding of IL-17A to its receptor, leading to activation of transcription factor NFκB and induction of IL 24, which repressed the Th17 cytokine program. In vivo, IL-24 treatment ameliorated Th17-induced EAU, whereas silencing of IL-24 in Th17 cells enhanced disease. This regulatory pathway also operated in human Th17 cells. Thus, IL-17A limits pathogenicity of Th17 cells by inducing IL-24. These findings may explain the disappointing therapeutic effect in targeting IL-17A in uveitis.
Project description:Dysregulation of Th17 differentiation was implicated in multiple inflammatory and autoimmune diseases including autoimmune uveitis. In the current study, we have provided evidence indicating that lactate-derived lactylation plays important roles in regulating Th17 differentiation. The lactylation level of CD4+ T cells was upregulated in EAU mice and inhibiting lactylation resulted in impaired EAU progression. We characterized the global lactylome of CD4+ T cells of normal and EAU mice. We found that the differentially lactylated proteins were enriched in pathways related to immune responses including leukocyte differentiation. Importantly, our results show that the lactylation level of Ikzf1 (K164) functions in regulating Th17 differentiation by differentially modulating gene expression patterns which are related to CD4+ T cell differentiation by CUT& Tag analysis. In view of the above mentioned well-documented evidence, Ikzf1 lactylation might represent an important regulator for Th17 differentiation in autoimmune uveitis.
Project description:T-helper 17 (Th17) cells play a dual role in immunological responses, serving as essential components in tissue homeostasis and host defense against microbial pathogens, while also contributing to proinflammatory conditions and autoimmunity. While Transforming Growth Factor-beta 1 (TGFβ1) is pivotal for the differentiation of non-pathogenic Th17 cells, the role of TGFβ3 and Activin in steering Th17 cells toward a pathogenic phenotype has been acknowledged. However, the molecular mechanisms governing this dichotomy remain elusive. In this study, we demonstrate that the transcription factor Foxo1 is upregulated in a TGFβ1 dose-dependent manner, serving as a critical regulator that specifically modulates the fate of pathogenic Th17 cells. Analyses in both uveitis patients and an Experimental Autoimmune Uveitis (EAU) mouse model reveal a strong correlation between disease severity and diminished Foxo1 expression levels. Ectopic expression of Foxo1 selectively attenuates IL-17A production under pathogenic Th17-inducing conditions. Moreover, enhanced Foxo1 expression, triggered by TGFβ1 signaling, is implicated in fatty acid metabolism pathways that favor non-pathogenic Th17 differentiation. Our drug screening identifies several FDA-approved compounds capable of upregulating Foxo1. Collectively, our findings offer compelling evidence that Foxo1 serves as a molecular switch to specifically control pathogenic versus non-pathogenic Th17 differentiation in a TGFβ1-dependent manner. These insights suggest that targeting Foxo1 could be a promising therapeutic strategy for autoimmune diseases, offering efficacy without compromising immune homeostasis.
Project description:Identification of the HDACs-regulated CDK6/ID2 signaling axis as a potential participant in the Th17-mediated autoimmune uveitis pathogenesis (PRJCA020882)
