CD8+ T cell longevity regulated by metabolic activity plays important roles in cancer immunotherapy. Although in vitro polarized, transferred IL-9-secreting CD8+ Tc9 cells exert greater persistence and antitumor efficacy than Tc1/CTL cells, the underlying mechanism remains unclear. Here, we show that tumor-infiltrating Tc9 cells display significantly lower lipid peroxidation than Tc1 cells in several mouse models, which is strongly correlated with their persistence. Using RNA-sequence and functional validation, we found that Tc9 cells exhibited unique lipid metabolic programs. Tc9 cell-derived IL-9 activated STAT3, upregulated fatty acid oxidation and mitochondrial activity, and rendered Tc9 cells with reduced ... More
CD8+ T cell longevity regulated by metabolic activity plays important roles in cancer immunotherapy. Although in vitro polarized, transferred IL-9-secreting CD8+ Tc9 cells exert greater persistence and antitumor efficacy than Tc1/CTL cells, the underlying mechanism remains unclear. Here, we show that tumor-infiltrating Tc9 cells display significantly lower lipid peroxidation than Tc1 cells in several mouse models, which is strongly correlated with their persistence. Using RNA-sequence and functional validation, we found that Tc9 cells exhibited unique lipid metabolic programs. Tc9 cell-derived IL-9 activated STAT3, upregulated fatty acid oxidation and mitochondrial activity, and rendered Tc9 cells with reduced lipid peroxidation and resistant to tumor or ROS induced ferroptosis in TME. IL-9 signal deficiency, inhibiting STAT3 or fatty acid oxidation increased lipid peroxidation and ferroptosis of Tc9 cells, resulting in impaired longevity and antitumor ability. Similarly, human Tc9 cells also possessed lower lipid peroxidation than Tc1 cells and tumor-infiltrating CD8+ T cells expressed lower IL-9 and higher lipid peroxidation- and ferroptosis-related genes than circulating CD8+ T cells in melanoma patients. This study indicates that lipid peroxidation regulates Tc9-cell longevity and antitumor effects via IL-9-STAT3-fatty acid oxidation pathway and regulating T-cell lipid peroxidation can be used to enhance T-cell based immunotherapy in human cancer.
