人子宫颈癌异常表达程序性死亡配体-1并促CD4+ T和CD8+ T细胞凋亡

Promotion of apoptosis of CD4+ T and CD8+ T lymphocytes induced by aberrant expression of programmed death ligand-1 in human cervical carcinomas

摘要:

目的：探讨程序性死亡配体－１（Programmed death ligand-1，PD-L1）在人子宫颈癌的表达及其与肿瘤内CD4+ T和CD8+ T细胞浸润的相关性，体外实验观察重组人PD-L1蛋白对宫颈癌患者外周血T细胞凋亡的影响。方法：采用免疫组化SP法检测PD-L1在10例正常人宫颈组织和67例宫颈癌组织中的表达以及死亡受体-1（Programmed death receptor-1，PD-1）在宫颈癌内浸润淋巴细胞的表达；TUNEL法检测肿瘤内浸润的淋巴细胞凋亡；免疫荧光分析宫颈癌内浸润的CD4+ T和CD8+ T淋巴细胞数量；流式细胞术分析PD-L1促进宫颈癌患者外周血活化CD4+ T和CD8+ T细胞凋亡情况。结果：正常子宫颈上皮不表达PD-L1；宫颈癌PD-L1的表达率为70%（47/67）。部分宫颈癌内浸润的淋巴细胞表达PD-1，且淋巴细胞存在凋亡现象。PD-L1阳性宫颈癌肿瘤内浸润的CD8+ T细胞数量明显减少（P＜0.05）。体外实验发现PD-L1与健康人或宫颈癌患者外周血活化T细胞混合培养48 h后，T细胞凋亡率明显高于空白组，２组平均凋亡率分别为（32.8±1.4）%、（38.3±1.5）%（P＜0.05）和（27.7±1.3）%、（30.9±1.9）%（P＜0.05）；抗PD-1抗体使PD-L1诱导的T细胞凋亡率下降，分别为（29.8±1.6）%和（31.6±1.4）%（P >0.05）。PD-L1对人外周血活化CD4+ T和CD8+ T细胞均有促凋亡作用。结论：人子宫颈癌异常表达PD-L1与肿瘤内浸润的淋巴细胞凋亡及CD8+ T细胞数量减少有关。PD-L1经PD-1促进活化的CD4+ T和CD8+ T细胞凋亡。

Abstract:

Objective：To investigate the expression of programmed death ligand-1（PD-L1） in human cervical carcinoma and the association between PD-L1 expression and T cell infiltration and to observe the effect of PD-L1 on apoptosis of active peripheral blood T lymphocytes of patients with cervical cancer in vitro. Methods：PD-L1 and programmed death receptor-1（PD-1） in human cervical carcinoma expressions were determined in 10 cases of normal cervical tissues and 67 cases of cervical carcinoma tissues by immunohistochemistry staining；the apoptosis of tumor infiltrating lymphocytes was examined by TUNEL assay；the number of tumor infil－trating CD4+ T and CD8+ T lymphocytes was determined by immunofluorescent staining and the apoptotic promoting effect of recombi－nant human PD-L1 protein on peripheral blood CD4+ T and CD8+ T lymphocytes was analyzed by flow cytometry. Results：No expression of PD-L1 in normal cervical epithelium was observed but expression of PD-L1 was found in 70%（47/67）cervical cancer tissues. PD-1 expression was found in part of tumor infiltrating lymphocytes. Some tumor infiltrating lymphocytes showed apoptosis. The tumor infiltrating CD8+ T cells were significantly reduced in PD-L1 positive cervical carcinoma cases（P＜0.05）. In vitro，recombinant hu－man PD-L1 induced apoptosis of activated peripheral blood T lymphocytes of healthy people and cervical cancer patients and the T cell apoptotic rates were significantly higher than those in blank group，which were （32.8±1.4）%，（38.3±1.5）%（P＜0.05） and （27.7±1.3）%，（30.9±1.9）%（P＜0.05）respectively. Anti-PD-1 antibody depressed PD-L1 induced T cells apoptosis，the apoptotic rates were （29.8±1.6）% and （31.6±1.4）%（P >0.05）. PD-L1 induced apoptosis of peripheral blood CD8+ T and CD4+ T cells. Con－clusions：PD-L1 is aberrantly expressed in cervical cancer. The expression of PD-L1 associates with lymphocytic apoptosis and de－crease of tumor infiltrating CD8+ T cells. PD-L1 promotes apoptosis of activated CD4+ T and CD8+ T cells by PD-L1/PD-1 pathway.