B7-H1在人骨髓间充质干细胞上的表达及其对T淋巴细胞增殖的影响

Expression of B7-H1 Molecule on Human Bone Marrow Mesenchymal Stem Cells and Its Effects on T lymphocyte Proliferation

目前关于人骨髓间充质干细胞(hBMMSC)的免疫调节机制尚不完全清楚。为探讨B7-H1在hBMSC上的表达水平及hBMMSC的免疫调节机制是否与B7-H1介导的信号通路(B7-H1/PD-1)有关,首先分离、培养、鉴定hBMMSC,采用流式细胞术、RT-PCR、Western-blot检测B7-H1在hBMMSC上的表达水平。进一步采用混合淋巴细胞培养法(MLC)观察hBMMSC对T淋巴细胞增殖的抑制作用,然后使用功能级的抗B7-H1单克隆抗体阻断B7-H1,用CCK-8试剂盒检测阻断前后T淋巴细胞增殖活性。结果表明:hBMMSC高表达B7-H1分子;表达B7-H1的hBMMSC能有效地抑制T淋巴细胞的增殖,其抑制作用与hBMMSC数量呈剂量依赖性;使用抗B7-H1单克隆抗体阻断B7-H1后hBMMSC对T淋巴细胞增殖的抑制作用显著降低,抑制率由64.1%降低至38.75%。结论:B7-H1在hBMMSC上高表达,B7-H1介导的信号通路(B7-H1/PD-1)参与了hBMMSC的免疫调节作用。

The mechanisms of human bone marrow mesenchymal stem cells （hBMMSCs）-mediated immunomodulation are still not be completely clarified. In order to investigate the expression of B7-H1 on hBMMSCs and to explore whether B7-HI mediated signaling pathway （B7-H1/PD-1） involves in the mechanisms of hBMMSCsmediated immunomodulation, the hBMMSCs were isolated, cultured and identified, the B7-H1 expression on hBMMSCs was detected by flow cytometry, RT-PCR, and Western blot. The inhibitory effect of hBMMSCs on proliferation of T lymphocytes was observed in mixed lymphocyte culture, and then the functional anti-B7-H1 monoclonal antibody （mcAb） was used to block B7-H1, the proliferation of T lymphocytes was detected by using CCK-8. The results indicated that hBMMSCs highly expressed B7-H1 molecule, hBMMSCs effectively inhibited the proliferation of T lymphocytes with a dose-dependent manner, and the inhibitory proliferation of T lymphocytes by hBMMSCs could be partially restored when the anti-B7-H1 mAb was used to block the B7-H1, the inhibitory rate of T lymphocyte proliferation decreased from 64.1% to 38.75%. It is concluded that B7-H1 highly expresses on hBMMSCs, the B7-H1 mediated signaling pathway（ BT-H1/PD-1 ） involves in the mechanisms for hBMMSCs-mediated immunomodulation.