Calcium signaling controls pathogenic Th17 cell-mediated inflammation by regulating mitochondrial metabolism

Pathogenic Th17 cells play an important role in many autoimmune and inflammatory diseases. Their function is dependent on signaling through the T cell receptor (TCR) and cytokines that activate the transcription factor signal transducer and activator of transcription 3 (STAT3). TCR engagement activates stromal interaction molecule 1 (STIM1) and calcium (Ca2+) influx through the Ca2+ release-activated Ca2+ (CRAC) channel. We here show that deletion of STIM1 and Ca2+ influx in T cells expressing a hyperactive form of STAT3 (STAT3C) attenuates pathogenic Th17 cell function and multiorgan inflammation associated with STAT3C expression. Deletion of STIM1 in pathogenic Th17 cells impairs the expression of nuclear encoded mitochondrial electron transport chain genes and oxidative phosphorylation (OXPHOS) but enhances reactive oxygen species (ROS) production. Deletion of STIM1 or inhibition of OXPHOS is associated with impaired Th17 cell function and a non-pathogenic Th17 gene expression signature. Our findings establish STIM1 and Ca2+ signals as a critical regulator of OXPHOS and oxidative stress in pathogenic Th17 cells and multiorgan inflammation. Comparing the transcriptome of in vitro differentiated pathogenic Th17 cells from Stat3CSTOPf/flCD4Cre and Stim1fl/flStat3CSTOPfl/flCD4Cre mice