IDO基因转染延长同种异基因大鼠移植心脏的存活

INDOLEAMINE 2,3-DIOXYGENASE GENE TRANSFER INDUCES LONG-TERM SURVIVAL OF CARDIAC ALLOGRAFT IN RATS

目的:了解逆转录基因载体介导的吲哚胺-2,3-加双氧酶(IDO)基因转染能否延长同种异基因大鼠移植心脏的存活时间及机理。方法:把同种异基因大鼠心脏移植模型(Lewis→BN)分成4组,A组为对照组,同种异基因大鼠心脏移植(Lewis→BN);B组:IDO基因转染后的供体心脏移植给受体大鼠;C组:空载体转染供体心脏,再移植给受体大鼠;D组:同种异基因大鼠心脏移植+CsA组(CsA5mg/kg/d×7天)。观察记录移植心脏的存活时间及术后6天组织病理学检查明确排斥反应的诊断和分级,RT-PCR检测术后6天移植心脏TNF-α的mRNA表达,FCM检测外周血活化的T细胞(CD3+CD25+)、有核细胞CD86+表达等方法探讨其机理。结果:A、B、C、D组移植心脏平均存活时间为7.2±0.45、13.2±2.16、7.1±0.62和15.6±3.21天,其中B、D组术后6天CD3+CD25+、有核细胞CD86+表达、供心组织急性排斥反应的强度和TNF-α的mRNA表达较A、C组显著降低(P<0.05),A、C组具有典型重度急性排斥反应特征而B、D组最轻。结论:逆转录基因载体介导的IDO基因转染能够延长移植心脏存活时间的作用,其机理包括抑制反应性T细胞、抑制有核细胞共刺激信号CD86表达、抑制心肌组织表达TNF-α等。

Objective：To evaluate the effect and investigate the mechanism of indoleamine 2,3-dioxygenase （IDO） gene transfer on heterotopic rat cardiac allograft survival. Methods：The experimental rats were divided into 4 groups： Group A served as control, donors received lml saline infusion into the vena cava 24 hours before heart transplantation; Group B that donors received reverse viruses containing IDO gene transfer at a dose of 5×10^9 pfu/ ml 24 hours before heart transplantation; Group C,donors received reverse viruses carriers transfer at a dose of 5× 10^9 pfu/ml 24 hours before heart transplantation;and group D received cyclosporine （CsA） 5mg/kg/d for 7 days after surgery. The survival time of donor hearts was observed; meanwhile, the mRNA expression of TNF-α in the graft were measured by RT-PCR 6 days following the operation. HE staining inspected all specimens of heart grafts 6 days after operation. The number of CD^3＋CD25^＋ cells, the CD86^＋ cells in the receptor peripheral blood lymphocytes were measured by flow cytometry 6 days after surgery.Results：The mean graft survival time of the group A, B, C and D were 7.2±0.45, 13.2±2.16, 7.1±0.62 and 15.6±3.21 days, respectively. There were significant differences in the number of CD3^＋CD25^＋, the expression of CD86 on the APC, the expression of mRNA of TNF-α and the degrees of acute graft rejection 6 days after surgery between group B and group A, group B and group D （P〈0.05）. The typical features of acute rejection were more marked in group A and group C and less in group B and group D.Conclusion ：The results showed that the graft survival time of group B was longer than that of group A or group C, IDO gene transfer can prolong the allo-graft survival in rat cardiac transplantation. Multiple mechanisms, including eliminatiing active T cells, T cells anergy and suppression the expression of mRNA of TNF-α in the graft were probably involved in the process.