STAT4 controls pathogenicity of CD4 Th17 via IL-10 suppression 2310000

Abstract

Abstract Introduction CD4 T cells, including Th17 cells (Th17), are central to the development of numerous autoimmune and chronic inflammatory diseases, such as Multiple Sclerosis (MS) and Inflammatory Bowel Disease (IBD). Furthermore, mutations in the STAT4 locus have been identified in IBD and MS patients, diseases driven by pathogenic Th17. Our lab has revealed that STAT4 expression in Th17 is required for autoimmune experimental encephalitis (EAE) induction. Our preliminary findings indicate that CD4 Type 1 Regulatory cells (Tr1) and Th17 produce more anti-inflammatory IL-10 in the absence of STAT4. Given the role of pathogenic Th17 in both diseases, we hypothesize that STAT4 induces a pathogenic transcriptional program in Th17 while reducing IL-10 expression in Tr1 and Th17, thus aggravating CD4 T cell-driven colitis. Methods To test this hypothesis, naïve CD4 T cells were isolated from wild type (WT) and STAT4 knockout (KO) IL-10 reporter mice, activated in vitro under Th17 or Tr1 conditions and analyzed for cytokine production via flow cytometry, ELISA, and RT-qPCR. We performed RNA sequencing of in vitro differentiated IL-10+ WT and STAT4 KO Th17 to identify differentially expressed genes. To probe the pathogenic function of STAT4 in vivo, we transferred WT and STAT4 KO naïve CD4 T cells to induce colitis. Disease severity was assessed by the Disease Activity Index and fecal lipcalin-2. We analyzed the CD4 profiles from the spleen, mesenteric lymph nodes, and colon using flow cytometry. To test the STAT4-IL-10 axis in colitis, we depleted IL-10+ CD4 T cells during colitis and evaluated disease severity. Results We found that STAT4 confers a pathogenic transcriptional program in Th17 in vitro. Notably, STAT4 suppresses IL-10 in both Th17 and Tr1 cells. In colitis, STAT4 modulates disease severity by downregulating IL-10, worsening disease. Conclusion Taken together, STAT4 plays a role in Th17 pathogenicity by inducing a pathogenic transcriptional program that antagonizes IL-10 expression and production. Funding Source R01AI186373-01A1, R01DK125870, R01DK125870-04, T32AI007051 Topic Categories Immune Response Regulation: Molecular Mechanisms (IRM)