Mitochondrial ATP production promotes T cell differentiation and function by regulating chromatin accessibility [RNAseq2]

Immune elimination of chronic infection or cancer requires cytotoxic CD8 T cells that adopt and maintain an effector phenotype. Cytotoxic T cell function is a bioenergetically demanding process and T cells subjected to chronic antigen exposure have compromised effector function despite high rates of glycolysis. Here we report the ability of the short chain fatty acid, D-a-hydroxybutyrate, to act as a signaling molecule that increases mitochondrial ATP production and drives the conversion of proliferating T cells into cytotoxic effector cells. DAHB signaling switches ATP production from glycolysis to fatty acid oxidation, even in glucose-replete media. This conversion suppresses both AMPK phosphorylation and the integrated stress response (ISR) in activated T cells while significantly elevating the level of the phosphagen, phosphocreatine (PCr). Both the PCr bioenergetic reserve and oxidative phosphorylation were required for T cell effector differentiation. DAHB-induction of CD8-effector gene transcription was coupled to bioenergetics by enhanced ATP-dependent remodeling of chromatin accessibility at effector gene loci. DAHB enhanced CD8 T cell antitumor activity both in vitro and in vivo, and DAHB treatment of transferred T cells led to persistent in vivo antitumor effects. Together, these findings link cellular bioenergetics to the regulation of chromatin accessibility and gene expression required to support effector function. Overall design: RNA-seq of 100,000 activated mouse CD8 T cells treated with NaCl (20mM, Ctrl), DAHB (20mM) or DAHB+Oligomycin (10nM) (DAHB+O) overnight followed by extraction.

清除慢性感染或癌症的免疫应答，依赖于能够获得并维持效应表型的细胞毒性CD8 T细胞（cytotoxic CD8 T cells）。细胞毒性T细胞的功能是一项高能量需求的生物学过程，而长期暴露于抗原的T细胞即便糖酵解速率极高，其效应功能仍会受损。本研究报道，短链脂肪酸D-α-羟基丁酸（D-a-hydroxybutyrate，以下简称DAHB）可作为信号分子，提升线粒体ATP生成水平，并驱动增殖性T细胞向细胞毒性效应细胞转化。DAHB介导的信号通路可将ATP的产生途径从糖酵解切换至脂肪酸氧化，即便在葡萄糖充足的培养基中亦是如此。该转换可抑制活化T细胞中的AMP活化蛋白激酶（AMPK）磷酸化与整合应激反应（integrated stress response，ISR），同时显著升高磷酸肌酸（phosphocreatine，PCr）的含量。磷酸肌酸的生物能储备与氧化磷酸化，均为T细胞效应分化所必需。DAHB诱导的CD8效应基因转录，通过增强效应基因位点处染色质可及性的ATP依赖性重塑，与细胞生物能学过程实现耦联。DAHB在体外与体内均可增强CD8 T细胞的抗肿瘤活性，且对过继转移的T细胞进行DAHB处理，可产生持久的体内抗肿瘤效应。综上，本研究结果揭示了细胞生物能学与调控染色质可及性及支持效应功能所需基因表达的过程之间的关联。实验设计：将10万个活化的小鼠CD8 T细胞分别用氯化钠（NaCl，20mM，对照组）、DAHB（20mM）或DAHB+寡霉素（Oligomycin，10nM，DAHB+O）处理过夜后提取样本，进行RNA测序（RNA-seq）。