大鼠心脏移植模型中mTOR C1/C2信号通路在消除慢性排斥反应中的作用

Role of mTOR C1/C2 pathways involve in abrogation of chronic rejection in rat heart transplantation model

目的 研究抑制了慢性排斥反应的大鼠模型中,T淋巴细胞中哺乳动物雷帕霉素靶蛋白-丝/苏氨酸蛋白激酶（mTOR）通路的各成分是否发生改变,探讨mTOR信号通路在抑制慢性排斥反应中的作用.方法 受体August-Copenhagen-Irish（ACI）大鼠与供体Wistar-Furth （WF）大鼠接受腹腔内异位心脏移植术.实验组大鼠给予慢性排斥反应消除处理,即术前给予经改造的Ⅰ类主要组织相容性复合物（MHC Ⅰ）,并给予亚治疗量环孢素（CsA）（10 mg/kg,3d）,治疗对照组于术后给予亚治疗量CsA（10 mg/kg,3 d）,空白对照组不进行处理.将每组大鼠分为在术后1、3、7d处死的3个亚组,每个亚组大鼠数量为5只.分别在亚组对应天数处死大鼠,获取脾脏样本进行T细胞提取与蛋白免疫印迹（Western blot）分析.结果 蛋白免疫印迹结果表明,在消除了慢性排斥反应的移植心脏中（实验组）,对雷帕霉素敏感的复合体1 （mTOR C1）的mTOR与mTOR调节相关蛋白（Raptor）下调,对雷帕霉素不敏感的复合体2（mTOR C2）的伴侣分子（Rictor）与哺乳动物应激活化蛋白激酶相互作用蛋白1 （Sin1）下调,mTOR调节因子（Deptor）与mTOR通路下游目标分子（Rac1）也受到抑制.结论 在消除了慢性排斥反应的大鼠心脏移植模型中,mTORC1和C2通路均受到影响,同时影响了细胞增殖调节（mTOR C1）和细胞运动调节（mTOR C2）.因此,选择性地对T细胞肌动蛋白细胞骨架通路进行抑制,可成为新的免疫抑制剂发展方向.

Objective To study the expression of the components of the mammalian rapamycin target protein （mTOR） pathway in T lymphocytes in rats with chronic rejection （CR）,and to explore the role of mTOR pathway in the inhibition of CR.Methods ACI rat recipients received intraperitoneal ectopic cardiac transplantation with Wistar-Furth rat hearts.In the experimental group,a mutated class Ⅰ major histocompatibility complex （MHC Ⅰ） that can eliminate CR was delivered into recipients prior-operation,and a sub-therapeutic cyclosporine A （CsA） （10 mg/kg,3 d） was also administered.In the experimental control group,the heart allograft recipients were treated with sub-therapeutic CsA （10 mg/kg,3 d）.The blank controls were the untreated recipients.Each group was divided into three subgroups （5 rats in each subgroup） according to the sacrifice time on the postoperative 1st,3rd and 7th days.The spleen samples were taken for T cell extraction and Western blot analysis.Results Western blot results showed that rat heart allografts with abolished CR exhibited downregulation of the RAPAsensitive mTORC 1 elements including mTOR and Raptor,and down-regulation of the RAPA-insensitive mTORC2 elements including Rictor and Sin1.Conclusions Abrogation of CR in rat model system involves modulation of mTOR C1 and mTOR C2 pathways.The mTOR C1 pathway regulates cellular proliferation and the mTORC2 pathway regulates T-cell motility.Selective targeting of T-cell actin cytoskeletal pathways shows potential for pathway-targeted immunosuppression therapies.