MAPK通路抑制剂调控PD-L1表达改善细菌脓毒症T淋巴细胞免疫抑制

MAPK pathway inhibitors alleviate T lymphocyte immune suppression by regulating PD-L1 expression in bacterial sepsis

目的探讨在细菌脓毒症中丝裂原活化蛋白激酶(MAPK)通路抑制剂对树突状细胞PD-L1表达及T淋巴细胞免疫应答的影响。方法以细菌内毒素处理树突状细胞诱导细菌脓毒症免疫抑制,应用MAPK通路抑制剂阻断树突状细胞,采用流式细胞分析和免疫印迹分析评价树突状细胞PD-L1表达情况。采用BrdU细胞增殖试剂盒和γ-干扰素酶联免疫斑点试剂盒分别检测混合淋巴细胞共培养实验中T淋巴细胞增殖反应和细胞毒性T细胞反应水平。结果与对照组相比,模型组树突状细胞PD-L1表达显著上调,且T淋巴细胞增殖反应和细胞毒性T细胞反应均显著降低(P<0.05)。与模型组相比,SB203580/模型组树突状细胞PD-L1的表达水平显著下调(P<0.05),U0126/模型组和SP600125/模型组PD-L1表达未见显著变化(P>0.05)。混合淋巴细胞共培养实验中SB203580/模型组和αPD-L1/模型组T淋巴细胞增殖反应和细胞毒性T细胞反应均显著升高(P<0.05)。结论p38信号通路能够调控细菌脓毒症树突状细胞的PD-L1表达。应用p38通路抑制剂可降低细菌脓毒症树突状细胞的PD-L1表达并逆转T淋巴细胞免疫抑制现象。

This study was performed to investigate the effects of mitogen-activated protein kinase(MAPK)pathway inhibitors on the expression of PD-L1 in dendritic cells and the T lymphocyte immune response in gram negative bacterial sepsis.The immunosuppression model of bacterial sepsis was established by treating the dendritic cells with bacterial endotoxin.The MAPK pathways inhibitors were applied to block pathways of dendritic cells,and then the PD-L1 expression on dendritic cells were detected by flow cytometry and Western blotting.Furthermore,the levels of T lymphocyte proliferation response and cytotoxic T cell response in mixed lymphocyte co-culture experiments were detected by cell proliferation assay kit and enzyme-linked immunospot assay kit,respectively.Data showed that the PD-L1 expression of dendritic cells were significantly up-regulated in the model group compared with the control group,while the levels of T lymphocyte proliferation response and cytotoxic T cell response in the model group were significantly reduced(P<0.05).Then compared with the model group,the PD-L1 expression of dendritic cells were significantly down-regulated in the SB203580/model group(P<0.05),meanwhile the levels of T lymphocyte proliferation response and cytotoxic T cell response were both significantly increased in SB203580/model group andαPD-L1/model group(P<0.05).In conclusion,the p38 signaling pathway could regulate PD-L1 expression of dendritic cells in bacterial sepsis.The application of p38 pathway inhibitors could partially reduce the PD-L1 expression of dendritic cells and reverse T lymphocyte immunosuppression in bacterial sepsis.