C5aR在慢性移植物抗宿主病中的表达及其作用机制

摘要

目的:探讨补体5a(C5a)及其受体(C5aR)在慢性移植物抗宿主病(cGVHD)中的表达及其作用机制.方法:用流式细胞术检测20例cGVHD患者及9例健康供者外周血淋巴细胞中C5aR的表达及CD4+CD25+Foxp3+调节性T细胞(Tregs)在CD4+T细胞中的比例,并分析两者的相关性;将体外分离培养小鼠脾细胞分为对照组及重组小鼠C5a蛋白(rmC5a)刺激组,用流式细胞术检测2组Tregs在CD4+T细胞中的表达比例;另外,提取患者外周血单个核细胞进行体外培养,分为空白对照组及C5aR拮抗剂(C5aRA)组,用流式细胞术检测2组Tregs在CD4+T细胞中的表达比例.结果:cGVHD患者外周血淋巴细胞表面C5aR的表达明显增多,而Tregs在CD4+T细胞中的比例明显减少,两者呈显著负性相关(P<0.05);体外培养小鼠脾细胞结果显示C5a下调Tregs在CD4+T细胞中的比例;而体外培养患者外周血单个核细胞显示阻断C5aR可上调Tregs在CD4+T细胞中的比例.结论:C5a/C5aR可能通过抑制Tregs的分化来介导cGVHD的发生发展.%AIM:To investigate the expression and potential role of complement 5a receptor (C5aR) in chro-nic graft-versus-host disease (cGVHD).METHODS:The expression of C5aR on lymphocytes and the frequency of CD4+CD25+ Foxp3+ regulatory T cells (Tregs) in 20 cGVHD patients and 9 healthy donors was detected by flow cytometry.The correlation between the expression of C5aR and the percentage of Tregs in the cGVHD patients was analyzed.In addition, the splenocytes from the mice were cultured in vitro, and stimulated these splenocytes with recombinant mouse C5a protein (rmC5a).The peripheral blood mononuclear cells (PBMCs) from cGVHD patients were cultured in vitro, which was inhibited by C5aR antagonist (C5aRA).The frequency of Tregs in these splenocytes and the PBMCs were evaluated by flow cytometry.RESULTS:The expression of C5aR on the lymphocytes was significantly increased in the cGVHD patients compared with the healthy donors, while the percentage of Tregs was markedly lower in the cGVHD patients.The expression of C5aR was negatively correlated with the percentage of Tregs.Furthermore, the development of Tregs was suppressed by rmC5a stimulation, but was promoted by C5aRA in vitro.CONCLUSION:C5aR elevation is associated with Treg reduction in cGVHD, indicating that C5aR may play a potential role in suppressing Tregs, resulting in the incidence of cGVHD.