Early T Cell Signalling Is Reversibly Altered in PD-1+ T Lymphocytes Infiltrating Human Tumors

To improve cancer immunotherapy, a better understanding of the weak efficiency of tumor-infiltrating T lymphocytes (TIL) is necessary. We have analyzed the functional state of human TIL immediately after resection of three types of tumors (NSCLC, melanoma and RCC). Several signalling pathways (calcium, phosphorylation of ERK and Akt) and cytokine secretion are affected to different extents in TIL, and show a partial spontaneous recovery within a few hours in culture. The global result is an anergy that is quite distinct from clonal anergy induced in vitro, and closer to adaptive tolerance in mice. PD-1 (programmed death -1) is systematically expressed by TIL and may contribute to their anergy by its mere expression, and not only when it interacts with its ligands PD-L1 or PD-L2, which are not expressed by every tumor. Indeed, the TCR-induced calcium and ERK responses were reduced in peripheral blood T cells transfected with PD-1. Inhibition by sodium stibogluconate of the SHP-1 and SHP-2 phosphatases that associate with several inhibitory receptors including PD-1, relieves part of the anergy apparent in TIL or in PD-1-transfected T cells. This work highlights some of the molecular modifications contributing to functional defects of human TIL.

为优化癌症免疫治疗（cancer immunotherapy），需更深入阐明肿瘤浸润T淋巴细胞（tumor-infiltrating T lymphocytes, TIL）功能低下的内在机制。本研究针对三类肿瘤（非小细胞肺癌NSCLC、黑色素瘤及肾细胞癌RCC）切除后即刻分离的人源TIL的功能状态开展了系统性分析。研究发现，多条信号通路（钙信号通路、ERK与Akt磷酸化通路）及细胞因子分泌功能在TIL中呈现不同程度的受损，且此类功能异常可在体外培养数小时内出现部分自发性恢复。整体而言，此类TIL所呈现的功能无能状态，与体外诱导的克隆性无能存在显著差异，却更贴近小鼠体内的适应性耐受表型。程序性死亡蛋白1（programmed death-1, PD-1）在TIL中呈系统性表达，其单纯表达即可参与介导TIL的功能无能，而非仅在与配体PD-L1、PD-L2结合时发挥调控作用——此类配体并非在所有肿瘤组织中均有表达。实验证实，在转染PD-1的外周血T细胞中，T细胞受体（TCR）诱导的钙信号及ERK应答均受到明显抑制。葡萄糖酸锑钠（sodium stibogluconate）可抑制SHP-1与SHP-2磷酸酶的活性，这类磷酸酶可与包括PD-1在内的多种抑制性受体相结合；该抑制剂可部分缓解TIL或转染PD-1的T细胞中显现的功能无能状态。本研究揭示了若干可导致人源TIL功能缺陷的分子修饰机制。