PLPP1-deficiency-mediated ferroptosis induced by PD-1 signaling impairs antitumor activity of intratumoral CD8+ T cells III.

Metabolic programming plays a crucial role in T-cell activation. Herein, we describe how phospholipid metabolism regulates CD8+ T-cell function in patients with cancer. We found that phosphatidylcholine (PC) and phosphatidyl ethanolamine (PE) levels were lower in intratumoral CD8+ T cells than in circulating CD8+ T cells. The expression of phospholipid phosphatase 1 (PLPP1), an enzyme that catalyzes PE and PC synthesis, was also downregulated in CD8+ T cells upon infiltrating tumors. Moreover, unsaturated fatty acid-mediated ferroptosis was a major factor impairing the antitumor function of PLPP1-deficient CD8+ T cells infiltrated in tumors, accompanied by enhanced reactive oxygen species production and lipid peroxidation. The activation of programmed cell death 1 (PD-1) signaling in CD8+ T cells suppressed the PLPP1 expression by increasing GATA1 binding to the promoter region of PLPP1. PLPP1 expression was upregulated after anti-PD-1 therapy. Our findings revealed therapeutic potential of enhancing PLPP1 levels to restore CD8+ T-cell function. Overall design: PLPP1fl/fl and Lckcre-PLPP1fl/fl CD8+ T cells infiltrated in B16 tumors after anti-PD-1 therapy were isolated for single cell RNA-seq (scRNA-seq). scRNA-seq of CD8+ T cells was performed by Analytical Biosciences Beijing Limited

代谢编程在T细胞活化过程中发挥关键作用。本研究阐明了磷脂代谢如何调控癌症患者体内CD8+ T细胞的功能。我们发现，肿瘤内CD8+ T细胞中的磷脂酰胆碱（phosphatidylcholine, PC）与磷脂酰乙醇胺（phosphatidyl ethanolamine, PE）水平低于循环CD8+ T细胞。催化PE与PC合成的酶——磷脂磷酸酶1（phospholipid phosphatase 1, PLPP1），其表达在浸润肿瘤的CD8+ T细胞中同样出现下调。此外，不饱和脂肪酸介导的铁死亡是损伤肿瘤浸润性PLPP1缺陷型CD8+ T细胞抗肿瘤功能的主要因素，该过程伴随活性氧生成与脂质过氧化水平的升高。CD8+ T细胞中程序性死亡受体1（programmed cell death 1, PD-1）信号的激活，可通过增强GATA1与PLPP1启动子区域的结合，抑制PLPP1的表达。抗PD-1治疗后，PLPP1的表达出现上调。本研究结果揭示了通过上调PLPP1水平以恢复CD8+ T细胞功能的治疗潜力。
实验整体设计：将经抗PD-1治疗后浸润B16肿瘤的PLPP1fl/fl与Lckcre-PLPP1fl/fl CD8+ T细胞分离，用于单细胞RNA测序（single cell RNA-seq, scRNA-seq）。CD8+ T细胞的scRNA-seq实验由Analytical Biosciences Beijing Limited完成。