摘要
目的设计并构建靶向滋养细胞表面糖蛋白抗原2(trophoblast cell surface antigen2,Trop2)的嵌合抗原受体T(chimeric antigen receptor T cell,CAR-T)细胞,通过重复抗原刺激构建体外细胞耗竭模型,并探究其抗肿瘤活性及耗竭特性。方法基于靶向Trop2的戈沙妥珠单链抗体可变区片段(single-chain variable fragment,scFv)序列构建二代CAR质粒,进行逆转录病毒载体颗粒包装。采用Ficoll法分离健康志愿者外周血单个核细胞(peripheral blood mononuclear cell,PBMC),经OKT-3/IL-2活化后转导CAR病毒载体颗粒制备Trop2 CAR-T细胞,流式细胞术检测MYC标签评估CAR表达率。原代T细胞(primary T cell,P-T)组仅接受相同条件的培养基处理。体外建立人卵巢癌细胞(SKOV3)、人乳腺癌细胞(MDA-MB-453)及人肺癌细胞(A549)3种典型的实体肿瘤细胞模型,流式细胞术验证Trop2抗原表达,将CAR-T组、P-T组分别与肿瘤细胞共培养,通过荧光素酶法检测不同效应细胞与靶细胞数量比例时的杀伤效率。构建体外耗竭CAR-T模型,利用Incucyte活细胞成像系统动态监测CAR-T长期杀伤能力。流式细胞术检测CAR-T细胞的PD-1和TIM3表达水平,CBA法分析细胞因子分泌水平,结合转录组测序和RT-qPCR验证耗竭相关差异基因。结果成功构建了靶向Trop2的二代CAR-T细胞,标签蛋白MYC显示的CAR阳性率为55.42%,体外实验显示,与P-T组相比,其对Trop2高表达肿瘤细胞(MDA-MB-453、SKOV3)具有抗原特异性及剂量依赖性杀伤效应(P<0.001)。通过体外重复肿瘤刺激建立的CAR-T细胞耗竭模型分析表明,耗竭状态的Trop2 CAR-T细胞对肿瘤的杀伤能力降低,而P-T细胞几乎无杀伤作用。与原始状态相比,耗竭状态CAR-T细胞表面抑制性受体PD-1和TIM-3表达上调(P<0.001),细胞因子分泌功能减弱,转录组分析揭示耗竭细胞出现多个差异表达基因,涉及免疫应答、T细胞受体信号通路等过程呈现下调趋势,而凋亡相关通路呈现激活状态,RT-qPCR分析进一步表明IL3、IL5、IL13等免疫调节基因亦异常表达(P<0.05)。结论靶向Trop2的二代CAR-T细胞在体外重复抗原刺激诱导的耗竭进程中,表现出抗肿瘤活性下降以及效应功能减弱、耗竭相关分子表达上调等典型耗竭特性。
Objective To design and construct chimeric antigen receptor(CAR)T cells targeting Trop2,establish an in vitro cell exhaustion model through continuous antigen stimulation,and investigate their anti-tumor activity and exhaustion characteristics.Methods The second-generation CAR plasmid was constructed based on the single-chain variable fragment(scFv)sequence of Sacituzumab Govitecan targeting Trop2.The viral vector titer was determined by retroviral vector packaging and gradient dilution.Peripheral blood mononuclear cells(PBMCs)from healthy donors were isolated using Ficoll density gradient centrifugation,and CAR virus vectors were transduced into PBMCs activated with OKT-3/IL-2 to generate Trop2-targeted CAR T cells.CAR expression levels were assessed by flow cytometry using MYC tags.In vitro 3 tumor cell models were established,including human ovarian cancer cells(SKOV3),human breast cancer cells(MDA-MB-453),and human lung cancer cells(A549).The expression of the Trop2 antigen in these models was confirmed using flow cytometry.Additionally,luciferase assay was employed to evaluate the cytotoxic efficiency of Trop2-targeted therapy at various effector-to-target ratios.An in vitro CAR-T exhaustion model was developed,and the long-term killing ability of CAR-T cells was dynamically monitored using the Incucyte live-cell imaging system.The PD-1/TIM-3 phenotype of CAR-T cells was analyzed by flow cytometry,and cytokine secretion levels were quantified using the cytometric bead array(CBA).Transcriptomic sequencing and RT-qPCR were employed to validate the differentially expressed genes associated with exhaustion.Results The second-generation CAR T cells targeting Trop2 were successfully constructed.Compared to the P-T group,in vitro experiments demonstrated that these CAR T cells exhibited antigen-specific and dose-dependent cytotoxic effects against tumor cells with high Trop2 expression,such as MDA-MB-453 and SKOV3.A CAR-T cell exhaustion model established through repeated tumor antigen stimulation in vitro revealed that,compared to the initial state,the exhausted Trop2 CAR-T cells exhibited significantly reduced tumor-killing capacity while P-T cells showed almost no killing effect,the expression of inhibitory receptors(PD-1 and TIM-3)was up-regulated on the surface of exhausted CAR-T cells,and the secretion of effector cytokines was diminished.Transcriptomic analysis identified multiple differentially expressed genes in the exhausted CAR-T cells.Pathways related to immune response and T cell receptor signaling were down-regulated,while apoptosis-related pathways were activated.RT-qPCR further confirmed abnormal expression of immunoregulatory genes,including IL3,IL5,and IL13(P<0.05).Conclusion During continuous in vitro tumor antigen stimulation,the second-generation CAR-T cells targeting the Trop2 antigen demonstrate declined anti-tumor activity,weakened effector function and up-regulated expression of exhaustion-related molecules.
作者
刘秀盈
李昕展
朱晶晶
刘静静
冯义超
王建勋
Xiuying;LI Xinzhan;ZHU Jingjing;LIU Jingjing;FENG Yichao;WANG Jianxun(Coege of Beijing University of Chinese Medicine,Beijing;Dezhou Health Commission,Dezhou,Shandong,China)
出处
《陆军军医大学学报》
北大核心
2025年第15期1750-1759,共10页
Journal of Army Medical University
基金
高层次人才科研启动经费项目(9011451310032)。
