抗PD-L1抗体抑制小鼠非小细胞肺癌移植瘤的生长及其机制

Anti-PD-L1 antibody inhibits growth of non-small cell lung cancer xenograft in mice and its mechanisms

目的:研究抗程序性死亡蛋白配体1(programmed death-ligand 1,PD-L1)抗体对小鼠非小细胞肺癌的治疗效果,并探讨其可能的作用机制。方法:采用FCM法检测小鼠肺癌LLC和CMT167细胞表面PD-L1的表达情况,以及小鼠脾脏中骨髓来源免疫抑制细胞(myeloid-derived immunosuppressive cells,MDSCs)所占百分比。分别将小鼠肺癌LLC和CMT167细胞接种于C57BL/6小鼠皮下,构建小鼠肺癌皮下移植瘤模型,然后分别用抗PD-L1抗体和同型对照抗体治疗,观察小鼠肿瘤生长情况;采用免疫组织化学法分析小鼠肿瘤组织中CD8^+T细胞数量的变化趋势;通过对小鼠体质量进行监测,并采用HE染色法观察小鼠重要器官如肺、肝及肾的组织结构变化,评估抗PD-L1抗体治疗的安全性。结果:小鼠肺癌CMT167和LLC细胞中PD-L1高表达(P值均<0.01)。与对照组相比,抗PD-L1抗体能够明显抑制小鼠肺癌CMT167和LLC细胞皮下移植瘤的生长(P值均<0.01),并减轻肺癌移植瘤的质量(P<0.01)。抗PD-L1抗体治疗能明显减少肺癌细胞CMT167移植瘤小鼠脾脏中MDSCs所占百分比(P<0.001),同时促进移植瘤组织中CD8^+T细胞的浸润(P<0.001)。抗PD-L1抗体治疗对移植瘤小鼠的体质量,以及肺、肝和肾等主要器官的组织结构无明显影响。结论:抗PD-L1抗体治疗能够抑制小鼠非小细胞肺癌CMT167移植瘤的生长,这可能与降低小鼠脾脏中MDSCs比例并增加肿瘤组织中CD8^+T细胞数量有关,并且无严重的毒副作用。

Objective:To study the effect of anti-programmed death-ligand 1(PD-L1)antibody treatment on the mouse non-small cell lung cancer,and to explore its underlying mechanism.Methods:The expression of PD-L1 on the surface of mouse LLC and CMT167 lung cancer cells and the percentage of myeloid-derived immunosuppressive cells(MDSCs)in the spleen of mice were detected by flow cytometry analysis.The transplanted tumor model of mouse lung cancer were established by the subcutaneous injection of LLC and CMT167 mouse lung cancer cells.Tumor growth was monitored by measuring the tumor size every three days after treatment with anti-PD-L1 antibody and isotype.The number of CD8+T cells in tumor sections were counted by immunochemistry staining.The safety of anti-PD-L1 treatment was evaluated by monitoring the mouse body weight every three days and by determining the pathological alterations in major organs(lungs,livers,and kidneys)by hematoxylin-eosin staining.Results:PD-L1 was highly expressed in CMT167 and LLC mouse lung cancer cells(both P<0.01).The treatment with anti-PD-L1 antibody significantly inhibited the growth of mouse lung cancer CMT167 and LLC cells subcutaneously implanted tumors in mice(P<0.01)and reduced tumor weight(all P<0.01)compared with the control treatment group.The treatment with anti-PD-L1 antibody significantly reduced the percentage of MDSCs in the spleens(P<0.001)and increased the infiltration of CD8+T cells in tumor tissues in CMT167 cells transplanted mice(P<0.001).There’s no obvious change in mouse body weight and histological alterations in the tissues of lung,liver and kidney from the mice treated with anti-PD-L1 antibody.Conclusion:Anti-PD-L1 antibody therapy can inhibit the growth of CMT167 mouse lung cancer cell xenografts in mice,which may be related to the decrease of MDSCs in spleen and increase of CD8+T cell infiltration in tumor tissues.Anti-PD-L1 antibody shows no significant toxic and side effects in mice.