Histone H3K27 demethylases regulate human Th17 cell maturation and effector functions by impacting on metabolism [I]

T helper (Th) cells are CD4+ effector T cells that play an instrumental role in immunity by shaping the inflammatory cytokine environment in a variety of physiological and pathological situations, including autoimmune conditions such as ankylosing spondylitis. Here we identify KDM6A/KDM6B histone H3K27 demethylases by inhibitor and knockdown approaches as central regulators of human Th1, Th2 and Th17 subsets and establish a direct link between KDM6A/KDM6B in regulating Th17 cell metabolism. In mature Th17 cells demethylase inhibition leads to suppression of IL-17 cytokine levels and reduced proliferation through a pronounced ATF4 driven metabolic stress response in T cells derived from PBMC fractions of healthy donors and patients with ankylosing spondylitis. Metabolomic analyses reveal that Th17 T-cell differentiation is associated with an increase in glycolytic metabolism, pentosephosphate pathway activity and protein glycosylation intermediates. GSK-J4 treatment was shown to be overtly impactful on the cellular biochemistry of Th17 differentiated T-cells, with prominent effects on differentiation-related changes in glucose utilization, anabolic processes, and a remarkable change in amino acid and TCA cycle metabolism. During differentiation from naïve Th precursors to mature Th17 populations, demethylase inhibition with the prototypic inhibitor GSK-J4 leads to increases of repressive H3K27me3 chromatin marks, thereby down-regulating the required TH17 key transcription factor RORC and effectively suppressing metabolic reprogramming from a naïve T cell ground state to a differentiated subset. These data are consistent with an opposing effect of GSK-J4 on Th17 T-cell differentiation pathways directly related to proliferation and effector cytokine profiles. Examination of H3K27me3 histone modifications in Th17 cells.