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Smad3敲除有效改善小鼠心脏移植排斥反应
Deletion of Smad3 Improves Cardiac Allograft Rejection in Mice
【作者】 王莹莹；
【导师】 陈江华；
【作者基本信息】 浙江大学 ， 内科学， 2016， 博士
【摘要】 目的同种异型移植排斥是临床上大范围开展器官移植治疗终末期疾病的最大阻碍。转化生长因子β1 (TGF-β1)/Smad3信号通路通过直接作用与间接调控的方式作用于CD4+辅助性T(Th)细胞的分化发育和相关作用的行使,从而在急性移植排斥中起关键性的作用。我们用Smad3基因敲除小鼠做为受体构建同种异型心脏移植模型来研究Smad3对Th细胞在移植排斥中的作用。方法来自BALB/c小鼠的心脏分别移植到C57BL/6 Smad基因敲除小鼠和野生型小鼠来构建同种异型小鼠移植模型。通过每天指尖感受移植心脏搏动来判定移植物存活状态,并记录移植物生存时间。BALB/c小鼠的心脏移植到BALB/c小鼠作为对照组。处死小鼠时收集移植心,血和脾脏检测炎症与免疫相关的指标。结果我们发现在小鼠同种异型心脏移植中,Smad3作为TGF-p信号通路的关键转录因子,对不同亚型的T细胞的免疫反应有不同的调节作用。移植到Smad3敲除小鼠的心脏存活时间明显延长。Smad3敲除对移植物的保护作用与明显抑制促炎性细胞因子(IL-1β, INF-α, and MCP-1)在移植物中的表达和减少中性粒细胞和F4/80+巨噬细胞在移植物中浸润相关。更为重要的是,Smad3的缺失明显抑制了移植心中T-bet和IFN-γ的表达,而增加了GATA3和IL-4的表达,导致Thl型免疫反应较轻而主要表现为Th2型免疫反应。另外,尽管Smad3敲除小鼠中对移植物有保护作用的调节性T细胞的免疫反应减弱了,但Smad3缺失保护小鼠的移植心较少受到Th17细胞介导的心脏损伤。结论Smad3作为一个重要的调节因子参与调节小鼠心脏移植排斥反应。受体中Smad3的缺失导致移植心脏中发生的免疫反应从Thl型向Th2型转化,同时抑制了Th17介导的免疫反应。因此,TGF-β/Smad3通路有潜力成为治疗急性器官移植排斥反应的新靶点。
【Abstract】 ObjectivesAllograft rejection is the major problem in clinical organ transplantation. TGF-β1/Smad3 pathway directly and indirectly regulates CD4+T helper (Th) cell differentiation that plays critical roles in acute allograft rejection. We used Smad3 knockout (KO) mice as recipients to develop an allogeneic heart transplantation model and investigated the role of Smad3 in Th cell immune response in allograft rejection.MethodsDonor hearts from BALB/c mice were heterotopically transplanted into either C57BL/6 Smad3 KO or wildtype (WT) mice. Allograft survival time was calculated by surveillance of daily abdominal palpation. Heart transplantation from BALB/c mice to BALB/c mice was built as control group. Transplanted hearts, blood, spleens were harvested when the mice were sacrificed to test the inflammation and immune indexes.ResultsWe report here that Smad3 is a key transcriptional factor of TGF-β signaling that differentially regulates T cell immune responses in a mouse model of cardiac allograft rejection in which donor hearts from BALB/c mice were transplanted into Smad3 knockout (KO) and wild type (WT) mice. Results showed that the cardiac allograft survival was prolonged in Smad3 KO recipients. This allograft protection was associated with a significant inhibition of proinflammatory cytokines (IL-1β, TNF-α, and MCP-1) and infiltration of neutrophils, CD3+T cells, and F4/80+macrophages. Importantly, deletion of Smad3 markedly suppressed T-bet and IFN-y while enhancing GATA3 and IL-4 expression, resulting in a shift from the Thl to Th2 immune responses. Furthermore, mice lacking Smad3 were also protected from the Th17-mediated cardiac injury, although the regulatory T cell (Treg) response was also suppressed.ConclusionsIn conclusion, Smad3 is an important participant in mediating cardiac allograft rejection. Loss of Smad3 results in a shift from Thl to Th2 but suppressing Th17 immune responses. Thus, modulation of TGF-β/Smad3 signaling may be a novel therapy for acute allograft rejection.