摘要:
目的 建立小鼠原位左肺移植模型,探究抗CD3单抗缓解肺移植急性排斥损伤的作用机制,为其在临床肺移植的应用提供理论依据.方法 选取SPF级野生型BALB/c和C57BL/6小鼠,构建原位左肺移植模型,设置同种同型对照组(C57BL/6→C57BL/6,6只)、同种异型对照组(BALB/c→C57BL/6,6只),同种异型单抗处理组(BALB/c→C57BL/6,4只).术后第2~6天及第9天每日腹腔注射50 g抗CD3单抗.采用苏木精-伊红、马松染色以及CD3/髓过氧化物酶(MPO)免疫组化染色,观察各组移植肺T淋巴细胞和中性粒细胞浸润分布情况,进行急性排斥病理评分;实时荧光定量RT-PCR检测移植肺组织转录因子FoxP3和细胞因子IL-17A、IFN-γ的mRNA表达水平;流式细胞术检测受体小鼠脾脏中FoxP3+调节性T细胞(Treg)占CD4+T细胞的比例.结果 移植术后10天,同种同型组移植肺外观呈淡红色,柔软有弹性,病理学检测未见明显的炎症细胞浸润和组织损伤;同种异型对照组移植肺外观呈绛紫色,硬度增加;同种异型单抗处理组外观淡红柔软,与同种异型对照组比较,淋巴细胞、中性粒细胞浸润显著减少,急性排斥损伤病理评分降低.实时荧光定量RT-PCR结果显示,与同种同型组相比,同种异型组移植肺中IL-17A和IFN-γmRNA的表达水平升高;抗CD3单抗可降低移植肺中IL-17A与IFN-γmRNA表达水平,升高FoxP3mRNA表达水平.流式细胞术结果显示,与同种同型、同种异型对照组相比,单抗处理组小鼠脾脏中Treg占CD4+T细胞的比例显著升高.结论 抗CD3单抗可诱导CD4+FoxP3+Treg的分化并缓解肺移植急性排斥损伤.%Objective By using mouse orthotopic lung transplant model, we investigated the immune mechanisms of an-ti-CD3 induced lung allograft protection .Our study intends to further dissect the features of lung transplant immunology and to provide a novel therapeutic insight for the clinical application of anti-CD3 mAbs after lung transplantation.Methods Murine orthotopic allogeneic lung transplants were performed in C57BL/6 wild type(WT) mice using major histocompatibility complex (MHC) fully mismatched BALB/c donors.Syngeneic transplants were also performed in WT C57BL/6 mice using C57BL/6 donors.For immunosuppressive therapy, allograft recipients received 50g dose of anti-CD3 by intraperitoneal injection on days 2, 3, 4, 5, 6 and 9 post-operation(n=4).At day 10, histopathologic characteristics and rejection status of the pulmonary grafts were assessed.The severity of acute rejection was graded by the pathological score , and T cell and neutrophil infiltration in the pulmonary grafts was evaluated by immunohistochemical(IHC) staining for CD3 and myeloperoxidase(MPO) respective-ly.Real-time RT-PCR was performed for FoxP3, IL-17A and IFN-γexpression in the pulmonary grafts.The percentage of FoxP3+Treg in total CD4+T lymphocytes from the recipient spleens was analyzed by FACS.Results 10 days after transplan-tation, histopathologic examination demonstrated that there is no apparent acute rejection observed in the pulmonary isografts , whereas allografts from untreated recipients have marked inflammatory cell infiltration and pulmonary parenchyma lesion .IHC staining for CD3 and MPO showed that the allograft-infiltrating cells of perivascular layers are mainly T lymphocytes , and the cells around the small airways are mostly neutrophils .Anti-CD3 treatment significantly alleviated the acute rejection of pulmo-nary allografts, when compared with the untreated group.Real-time RT-PCR showed that the expression levels of IL-17A and IFN-γin allografts were markedly elevated compared to those in isografts, and anti-CD3 increased the expression of FoxP3, and reduced the expression of IL-17A and IFN-γin the pulmonary allografts.FACS analysis of splenocytes showed that the percent-age of Treg in total CD4+T lymphocytes increased significantly in the anti-CD3 treated allograft recipients, as compared with the isograft and untreated allograft recipients.Conclusion Anti-CD3 mAbs may alleviate acute rejection of the pulmonary al-lografts by promoting FoxP3 expression and Treg development.