阻断PD-L1/PD-1途径改善酵母多糖致伤小鼠脾脏树突状细胞的免疫耐受状态

Blocking PD-L1/PD-1 pathway alleviates immune tolerance of splenic dendrtic cells in mice stimulated by zymosan

目的探讨小鼠多脏器功能障碍综合征(multiple organ dysfunction syndrome,MODS)病程中共刺激分子和共抑制分子,在脾脏树突状细胞(dendritic cell,DC)的表达特征及其与耐受性DC形成的关系,并观察PD-L1抗体对DC免疫状态的改善效应。方法采用酵母多糖腹腔注射小鼠MODS模型。设对照组、MODS组和PD-L1抗体处理组。检测脾脏DC上MHC-Ⅱ、CD86、程序性细胞死亡受体-1(programmed death-1,PD-1)、PD-L1、PIR-B的表达水平及脾组织中IL-12和IL-10含量。结果脾脏DC上MHC-Ⅱ、CD86、PD-1和PD-L1表达在酵母多糖致伤后早期增加,而后下降;伤后5天和12天时,DC上MHC-Ⅱ、CD86表达减少,而PD-1、PD-L1及PIR-B表达大幅增加,脾组织中IL-12 p70降低,IL-12 p40和IL-10升高;PD-L1抗体可以上调MHC-Ⅱ和CD86的表达,而下调PIR-B的表达,降低脾组织IL-12 p40和IL-10的含量。结论酵母多糖诱导的小鼠MODS病程晚期,脾脏DC对共刺激和共抑制分子表达失衡,形成耐受性DC;PD-L1抗体通过干预PD-1/PD-L1途径改善DC免疫耐受状态,恢复DC的免疫活性。

Purpose To observe the expressive patterns of costimulatory and coinhibitory molecules on splenic dendritic cells （DC） during the development of multiple organ dysfunction syndrome （MODS） induced by zymosan and the relation with DC immunotolerance, and to explore whether anti-PD-L1 antibody could improve the immunoactivity of tolerogenic DC. Methods MODS mice model was established by injecting zymosan peritoneally. Mice were divided randomly into the control, MODS and PD-L1 groups. The expression of MHC- Ⅱ , CD86, PD-1, PD-L1, and PIR-B on splenic DC was detected, and the contents of IL-12 and IL-10 on spleen were determined. Results In zymosan-treated mice, the expression of MHC-Ⅱ , CD86 and PD-L1 on splenic DC was upregulated at the early stage, which was recovered subsequently. At 5 days and 12 days after zymosan injection, the expression of MHC-Ⅱ and CD86 decreased, but the expression of PD-L1, PD-1 and PIR-B increased significantly, which were accompanied by the abatement of IL-12 p70 content and the enhancement of IL-12 p40 and IL-10 expression in the spleen. Administration of anti-PD-L1 antibody prevented zymosan-induced downregulated expression of MHC-II and CD86 and the upregnlated expression of PIR-B on the splenic DC, decreased IL-12 p40 and IL-10 production in the spleen. Conclusions At the late stage of zymosan-induced mice MODS, there is unbalanced expression between co-stimulatory and coinhibitory molecules in splenic DC, which indicates the formation of immune tolerogenic DC. Anti-PD-L1 antibody could ameliorate the status of DC immunosuppression and recover the immunoactivity of DC.