Li Qing, Johnston Nathan, Zheng Xiufen, Wang Hongmei, Zhang Xusheng, Gao Dian, Min Weiping
Institute of Immunotherapy of Nanchang University, and Jiangxi Academy of Medical Sciences, Nanchang, China.
Department of Oncology, the Second Affiliated Hospital of Nanchang University, Nanchang, China.
Oncotarget. 2016 Aug 16;7(33):53735-53750. doi: 10.18632/oncotarget.10731.
T cell exhaustion is a state of T cell dysfunction that arises during many cancer. miRNAs are one of major gene regulators which result in translational inhibition and/or mRNA degradation. We hypothesized that miRNAs exist that can silence PD1 and act as a modulator in vitro to revert exhaustive status of T cells. We demonstrated that the exhausted T cells with inhibitory receptors (IRs) are significantly increased in the melanoma-bearing mice. Meanwhile, the differentiated miRNA profiles in PD1+ exhaustive T cells were identified using a miRNA array; 11 miRNAs were observed with significant altered levels in the exhausted T cells isolated from melanoma-bearing mice. Among those identified miRNA candidates, miR-28 was capable of binding to multiple IRs based on an in silico analysis and subsequently silencing PD1, as demonstrated by a dual luciferase assay. Moreover, the expression of PD1 was attenuated after transfection with miR-28 mimic. The ability of miR-28 in regulating T cell exhaustion was further evidenced by the fact that the expression of PD1, TIM3 and BTLA of exhausted T cells was increased by the inhibitor of miR28. On the other hand, miR-28 also regulated the PD1+ Foxp3+ and TIM3+ Foxp3+ exhaustive Treg cells in vitro. miR-28 regulating T cell exhaustion was also observed by its ability in reinstalling impaired secretion of cytokines IL-2 and TNF-α by exhausted T cells. This study is the first to discover the effect of miR-28 on T cell exhaustion, providing novel targets with potential use as therapeutic markers in cancer immunotherapy.
T细胞耗竭是一种在多种癌症发生过程中出现的T细胞功能障碍状态。微小RNA（miRNA）是导致翻译抑制和/或信使核糖核酸（mRNA）降解的主要基因调节因子之一。我们推测存在能够使程序性死亡蛋白1（PD1）沉默并在体外作为调节剂来逆转T细胞耗竭状态的miRNA。我们证明，携带黑色素瘤的小鼠中带有抑制性受体（IRs）的耗竭T细胞显著增加。同时，使用miRNA阵列鉴定了PD1+耗竭T细胞中分化的miRNA谱；在从携带黑色素瘤的小鼠中分离出的耗竭T细胞中，观察到11种miRNA的水平有显著变化。在那些鉴定出的miRNA候选物中，基于计算机分析，miR-28能够与多种IRs结合，随后使PD1沉默，双荧光素酶测定法证明了这一点。此外，用miR-28模拟物转染后，PD1的表达减弱。miR-28抑制剂增加了耗竭T细胞中PD1、T细胞免疫球蛋白和粘蛋白结构域分子3（TIM3）和B和T淋巴细胞衰减蛋白（BTLA）的表达，这一事实进一步证明了miR-28调节T细胞耗竭的能力。另一方面，miR-28在体外也调节了PD1+叉头框蛋白3（Foxp3+）和TIM3+ Foxp3+耗竭调节性T细胞（Treg）。通过其恢复耗竭T细胞受损的细胞因子白细胞介素-2（IL-2）和肿瘤坏死因子-α（TNF-α）分泌的能力，也观察到了miR-28对T细胞耗竭的调节作用。本研究首次发现了miR-28对T细胞耗竭的影响，为癌症免疫治疗提供了具有潜在用作治疗标志物的新靶点。
