The intestine harbours functionally distinct tissue-resident and inflammatory Th17 cells

Th17 cells are extensively studied because of their known pathogenic role in many inflammatory diseases, but are also important to support the integrity of the intestinal barrier in a non-inflammatory manner. Since therapeutic targeting of Th17 cell mediated pathologies carries the risk of inadvertently affecting protective Th17 cells, we set out to define the major distinctions between homeostatic tissue-resident Th17 cells and Th17 cells engaged in inflammatory reactions, focusing on the gut. We show here that homeostatic Th17 cells exhibit little plasticity towards expression of inflammatory cytokines, are characterised by a metabolism typical for quiescent or memory T cells, and do not participate in inflammatory processes. Infection-induced Th17 cells, on the other hand, show extensive plasticity towards pro-inflammatory cytokines, disseminate widely into the periphery and engage aerobic glycolysis in addition to oxidative phosphorylation typical for inflammatory effector cells. RNA-seq study comparing the gene expression of SFB-induced homeostatic vs. C. rodentium-induced inflammatory intestinal Th17 cells