No abstract

Signal transducer and activator of transcription 4 (STAT4) and STAT6 are key factors in the specification of helper T cells; however, their direct roles in driving differentiation are not well understood. Using chromatin immunoprecipitation and massive parallel sequencing, we quantitated the full complement of STAT-bound genes, concurrently assessing global STAT-dependent epigenetic modifications and gene transcription using cells from cognate STAT-deficient mice. STAT4 and STAT6 each bound over 4000 genes with distinct binding motifs. Both played critical roles in maintaining chromatin configuration and transcription of a core subset of genes through the combination of different epigenetic patterns. Globally, STAT4 had a more dominant role in promoting active epigenetic marks, whereas STAT6 had a more prominent role in antagonizing repressive marks. Clusters of genes negatively regulated by STATs were also identified, highlighting previously unappreciated repressive roles. Therefore, STAT4 and STAT6 play wide regulatory roles in T helper specification.

A novel isoform of Sox5, Sox5t, and c-Maf activate RORγt to induce Th17 cells. Sox5−/− mice exhibit impaired Th17 differentiation and are thus resistant to EAE and delayed-type hypersensitivity.

Objective Helios+FoxP3+CD4+ (Helios+) Treg cells are believed to be involved in the regulation of various autoimmune diseases; however, the regulatory mechanisms underlying the development of Helios+ Treg cells remain uncertain. This study was undertaken to elucidate the regulatory mechanisms of Helios expression in CD4+ T cells and its roles in transforming growth factor β (TGFβ)–induced Treg cell function. Methods We examined the expression of Helios in CD4+ T cells in patients with rheumatoid arthritis by DNA microarray analysis before and after treatment with biologic agents. We also examined the effect of interleukin‐6 (IL‐6) and TGFβ on Helios expression in CD4+ T cells in humans and mice. The effect of forced expression of Helios on murine induced Treg cell function was also examined. The role of FoxP3 in the induction and function of Helios was assessed by using CD4+ T cells from FoxP3‐deficient scurfy mice. Results Tocilizumab, but not tumor necrosis factor (TNF) inhibitors or abatacept, increased Helios expression in CD4+ T cells in patients with a good response. IL‐6 inhibited the TGFβ‐induced development of Helios+ induced Treg cells in both humans and mice. Both cell‐intrinsic FoxP3 expression and TGFβ signaling were required for Helios induction in murine induced Treg cells. The forced expression of Helios enhanced the expression of various Treg cell–related molecules and the suppressive function in murine induced Treg cells. Helios‐mediated enhancement of the suppressive function of induced Treg cells was obvious in FoxP3‐sufficient CD4+ T cells but not in FoxP3‐deficient CD4+ T cells. Conclusion Our findings indicate that Helios enhances induced Treg cell function in cooperation with FoxP3.