免疫检查点配体PD-L1对CAR-T细胞活性的增强作用及机制研究

尽管CAR-T治疗是现在较为有效的治疗B细胞恶性肿瘤的过继免疫疗法，但20-50%的患者经过治疗后仍会抗原阳性复发。目前认为，抑制CAR-T耗竭、延长其在患者体内的存活时间或将防止疾病复发。有关CAR-T的耗竭常关注CAR-T表达的PD-1和恶性细胞表达的PD-L1。然而我们发现，CAR-T中有一群PD-L1一过性高表达的细胞，体外研究证明该群细胞的增殖和杀伤活性均优于PD-L1阴性细胞。经免疫沉淀PD-L1后质谱分析，发现与PD-L1相互作用的蛋白中40%为蛋白酶体蛋白。因此，我们假设CAR可诱导PD-L1的表达，PD-L1通过稳定蛋白酶体正常功能，促进CAR-T的杀伤及生存。拟通过以下研究阐述：1）CAR如何调控PD-L1的表达；2）PD-L1如何影响CAR-T的功能；3）PD-L1影响CAR-T功能的反作用信号；4）CAR结构中引入PD-L1是否可影响CAR-T的存活，继而提高疗效。

Although CAR-T immunotherapy is an effective adoptive immunotherapy for the treatment of B cell malignancies, 20-50% of patients will antigen-positive relapse after treatment. At present, it is considered that inhibiting the exhaustion and prolonging the survival time of CAR-T in patients will prevent the antigen-positive relapse. About the exhaustion of CAR-T, we often pay attention to PD-1 expressed by CAR-T and PD-L1 expressed by malignant cells. However, our previous studies found that in the preparation of CAR-T, and after re-infusion CAR-T into patients , there was a group of CAR-T cells transiently high-expressed PD-L1, and in vitro studies proved that the proliferation and killing activity of this group of cells were superior to PD-L1 negative cells. After immunoprecipitation of PD-L1 in CAR-T cells, mass spectrometry analysis revealed that 40% of the proteins interacting with PD-L1 were proteasome proteins. Therefore, we hypothesized that CAR can induce the expression of PD-L1, and PD-L1 can promote the killing and survival of CAR-T cells by stabilizing the normal function of the proteasome. It is planned to elaborate through the following studies: 1) how CAR regulates the expression of PD-L1; 2) how PD-L1 affects the function of CAR-T; 3) the signal pathway of PD-L1 affecting CAR-T function; 4) whether introduce PD-L1 into the structure of CAR can affect the survival and efficacy of CAR-T.