A Th17 cell-intrinsic glutathione/mitochondrial-IL-22 axis protects against intestinal inflammation

The intestinal tract generates significant reactive oxygen species (ROS), but the role of T cell antioxidant mechanisms in maintaining intestinal homeostasis is poorly understood. We used T cell-specific ablation of the catalytic subunit of glutamate cysteine ligase (Gclc), which impaired glutathione (GSH) production, crucially reducing IL-22 production by Th17 cells in the lamina propria, which is critical for gut protection. Under steady-state conditions, Gclc deficiency did not alter cytokine secretion; however, C. rodentium infection induced increased ROS and disrupted mitochondrial function and TFAM-driven mitochondrial gene expression, resulting in decreased cellular ATP. These changes impaired the PI3K/AKT/mTOR pathway, reducing phosphorylation of 4E-BP1 and consequently limiting IL-22 translation. The resultant low IL-22 levels led to poor bacterial clearance, severe intestinal damage, and high mortality. Our findings highlight a previously unrecognized, essential role of Th17 cell-intrinsic GSH in promoting mitochondrial function and cellular signaling for IL-22 protein synthesis, which is critical for intestinal integrity and defense against gastrointestinal infections. Comparative gene expression profiling analysis of RNA-seq data for Th17 cells with and without Gclc knockout using Cd4Cre Gclc fl/fl mice. Cd4Cre Gclc fl/fl mice investigated with and without NAC (N-Acetyl Cysteine) treatment. Each condition with 3 Biological replicates included.

肠道可产生大量活性氧（reactive oxygen species, ROS），但T细胞抗氧化机制在维持肠道稳态中的作用仍不甚明确。我们采用T细胞特异性敲除谷氨酸半胱氨酸连接酶催化亚基（glutamate cysteine ligase, Gclc）的模型，该操作会损伤谷胱甘肽（glutathione, GSH）的生成，显著降低固有层中Th17细胞的IL-22分泌水平，而这一过程对肠道保护至关重要。在稳态条件下，Gclc缺失并不会改变细胞因子的分泌；但鼠柠檬酸杆菌（C. rodentium）感染会诱导ROS水平升高，破坏线粒体功能及TFAM驱动的线粒体基因表达，最终导致细胞ATP含量下降。上述变化会损伤PI3K/AKT/mTOR信号通路，降低4E-BP1的磷酸化水平，进而限制IL-22的翻译过程。由此产生的低IL-22水平会导致细菌清除能力受损、肠道严重损伤以及较高的死亡率。我们的研究发现揭示了Th17细胞内源性谷胱甘肽此前未被认知的关键作用：其可促进线粒体功能与细胞信号通路，以支持IL-22蛋白的合成，这对肠道完整性及抵御胃肠道感染均具有重要意义。本研究利用Cd4Cre Gclc fl/fl小鼠，对存在与不存在Gclc敲除的Th17细胞的RNA测序数据进行比较基因表达谱分析；同时对经N-乙酰半胱氨酸（N-Acetyl Cysteine, NAC）处理或未处理的Cd4Cre Gclc fl/fl小鼠开展相关实验，每组均设置3个生物学重复。