目的 探讨丝裂原活化的蛋白激酶（MAPK）信号通路在B7H1-Ig诱导Ⅰ型调节性T细胞（Tr1）分化过程中的作用。方法 以预包被而固相化的小鼠B7H1-Ig融合蛋白加抗CD3单克隆抗体（单抗）刺激新鲜分离的C57BL/6小鼠初始CD4+CD62L+T细胞，诱导其向Tr1细胞分化。Western blotting检测 MAPK信号通路（ERK1/2、p38 MAPK、JNK）的活化状况。在B7H1-Ig开始刺激时分别加入ERK1/2、p38和JNK通路特异性抑制剂PD98059、SB203580和SP600125，分别采用ELISA法、混合淋巴细胞反应（MLR）、流式细胞术和Western blotting分析检测抑制MAPK信号对B7H1-Ig刺激的CD4+T细胞产生的细胞因子分泌格局、功能及Foxp3表达的影响。结果 B7H1-Ig联合抗CD3单抗激活并诱导一群IL-10+IFN-γ+IL-5+IL-4low/-IL-2low/-Foxp3-Tr1细胞，通过分泌抑制性细胞因子IL-10发挥免疫抑制功能。Western blotting检测结果显示B7H1-Ig可激活CD4+T细胞中的p38 MAPK信号通路，对ERK1/2和JNK信号通路无明显影响。抑制p38 MAPK活性，可使B7H1-Ig诱导的CD4+T细胞IL-10和IL-5的分泌减少、免疫抑制功能减弱，促进B7H1-Ig刺激的CD4+T细胞向CD25+Foxp3+调节性T细胞（Treg）分化。结论 p38 MAPK信号通路的活化或抑制是参与调控由B7H1-Ig诱导的Tr1细胞分化及其与CD4+CD25+Foxp3+ Treg之间相互转化的重要分子机制。

Objective To investigate the effects of mitogen-activated protein kinase (MAPK) signaling pathway on B7H1-Ig fusion protein-initiated differentiation of type 1 regulatory T cells (Tr1). Methods Fresh isolated naive CD4+CD62L+T cells of C57BL/6 mice were stimulated with immobilized B7H1-Ig fusion protein plus anti-CD3 monoclonal antibody to induce Tr1 cells. The activities of three major MAPK (ERK1/2, p38MAPK, JNK) signaling pathways during the process of Tr1 cells differentiation were analyzed by Western blotting. In experiments, the specific inhibitors of ERK1/2, p38 and JNK (PD98059, SB203580 and SP600125) were added separately at the time of culture initiation, and the influences on cytokines secretion, immune function and Foxp3 expression of B7H1-Igstimulated CD4+T cells were detected respectively by ELISA, mixed lymphocyte reaction (MLR), flow cytometry and Western blotting. Results B7H1-Ig-plus-anti-CD3 stimulation activated and induced the generation of a subset of IL-10+IFN-γ+IL-5+IL-4low/-IL-2low/-Foxp3- Tr1 cells, which played immunosuppressive roles via secreting IL-10. Western blotting indicated that B7H1-Ig activated the p38 MAPK signaling pathway in CD4+T cells, while had no significant effect on ERK1/2 and JNK signaling pathways. Blocking p38 MAPK activity could significantly inhibit the production of IL-10 and IL-5 induced by B7H1-Ig in CD4+T cells, weaken the immunosuppressive function of B7H1-Ig-stimulated CD4+T cells and promote them to differentiate into CD25+Foxp3+Tregs. Conclusion The activation or inhibition of p38 MAPK signaling pathway is one of the important molecule mechanisms to control B7H1-Ig-induced Tr1 cells differentiation and transformation between Tr1 cells and CD4+CD25+Foxp3+Tregs.