基于NKG2D受体调控AML患者耗竭性γδ T细胞功能逆转及机制研究

How to reivse the T cell immunodeficiency to improve prognosis of leukemia is worthy to further investigate. Our previous study identified clonally expanded γδ T cell clone in blood from acute myeloid leukemia (AML) patients, however, the expression level of immune activated receptor NKG2D decreased, moreover some of γδ T cell subfamilies with high immune inhibited receptor PD-1 were related to poor prognosis Therefore, we hypothesize that the immune inhibited receptors may play an important role in the functional deficiency and exhaustion of γδ T cell immune response in AML patients. In this study, we intend to analyze the relationship between the alternations of the immune inhibited receptors (CTLA-4, Tim-3, TIGIT, BTLA, et la.) that related to the different γδ T cell subfamilies and the degree of γδ T cell functional exhaustion, and characterize the exhausted γδ T cell which related to the prognosis. On the other hand, through regulating the expression of NKG2D in exhausted γδ T cell, we will analyze the phenotype and activation function of γδ T cell, including the possibility of functional reversion with anti-leukemia effects. Most importantly, we will investigate the molecular mechanism of the reversion effect by using the RNA-seq,. Together, the study is expected to provide a new immunotherapy strategy for AML patients.

克服白血病患者T细胞免疫功能缺陷而改善预后仍是关键问题。我们前期发现尽管急性髓性白血病(AML)病人存在白血病相关的γδ T细胞克隆，但免疫激活性受体NKG2D表达水平下降，而高表达免疫抑制性受体PD-1的γδ T细胞亚群影响患者预后。故推测这些免疫抑制性受体可能是介导AML中γδ T细胞免疫功能抑制及耗竭的重要原因之一。因此本课题拟综合分析AML患者体内γδ T细胞功能亚群相关免疫抑制性受体（CTLA-4，Tim-3，TIGIT，LAG-3和BTLA等）改变情况及其与γδ T细胞功能耗竭程度的关系，鉴定与预后相关的耗竭性γδ T细胞表型特征，分析调控耗竭性γδ T细胞中NKG2D的表达后，γδ T细胞表型和活化功能包括抗AML效应等逆转的可能性，通过转录组测序分析逆转效应的相关通路分子机制，为AML病人的γδ T细胞免疫治疗提供新策略。

急性髓系白血病（AML）患者体内存在着一定程度的T细胞免疫功能缺陷，而T细胞免疫抑制受体介导的T细胞功能耗竭是其重要原因之一，筛选耗竭性T细胞特有的表型，靶向相关通路，可能逆转耗竭性T细胞的功能缺陷。γδ T细胞表面共表达TCR γδ链及NK细胞的重要受体NK细胞受体成员2（NKG2D），因此兼具了T细胞和NK细胞的功能，我们前期研究发现AML患者γδ T细胞上NKG2D表达水平下降，免疫杀伤功能存在异常。本项目研究了不同状态下AML患者外周血总γδ T细胞及其调节性亚群免疫效应分子NKG2D和CD226，免疫抑制分子TIGIT表达及分布情况；进一步临床相关性分析发现，AML患者外周血γδ T细胞上NKG2D/TIGIT及CD226/TIGIT表达失衡，并随患者获得缓解后发生分布动态变化。高比例的NKG2D-TIGIT+ γδ T细胞亚群和NKG2D-Foxp3+ γδ T细胞亚群是AML患者预后不良的独立危险因素，提示不同γδ T细胞亚群可作为AML患者疗效及预后的参考指标；进一步免疫调控NKG2D及TIGIT信号通路，上调γδ T细胞中NKG2D分子或下调TIGIT分子表达，γδ T细胞的杀伤功能在一定程度上得到逆转，为AML新的细胞免疫治疗策略提供基础研究资料。