磷酸酶wip1在移植排斥反应中的作用及机制研究

Emerging evidence highlights the importance of a new member of the PP2C family of phosphatase, Wild-type p53 induced phosphatase 1 (Wip1), in regulating DNA damage-induced and tumorigenesis-induced networks. The protein phosphatase Wip1 was identified as a proto-oncogene with expression induced in response to γ or UV radiation in a p53-dependent manner. Latest studies showed that Wip1 also played a critical role in the regulation of both innate and adoptive immunity. However, there is still no related report of the exact role of Wip1 in the regulation in transplantation immunity. In our intial study of cardiac graft rejection, compared with Wip1+/+ recipient mice, survival of allografts were prolonged significantly in Wip1-/- recipient mice. Interestingly, with the perioperative treatment of Rapamycin, the specific inhibitor of mTOR pathway, 75% of allografts could gain longterm survival in Wip1-/- recipient mice (＞60d), with the upregulation of regulatory T cells (Treg) in peripheral blood, spleen and allografts. These data might shed the light on the role of Wip1 phosphatase in the regulation of allograft rejection, and the induction and enhancement of Treg might be one of possible mechanisms. In the present study, we aimed to investigate the celluar and molecular mechanisms of the regulation of allograft rejection in Wip1-dependent signaling pathways by employing transgenic mice such as Wip1-/- , ATM-/- and Wip1-/-ATM-/- mice, which would received skin/cardiac transplantation and in vitro fuctional studies. Based on the experimental evidence, We hope to propose a new idea of the therapuetic strategy of selectively immunosuppression in clinical application.

磷酸酶Wip1是PP2C家族成员，最初被认为是依赖于p53高表达的原癌基因，相关研究集中于DNA修复、肿瘤发生调控等领域。最新研究表明，无论是在固有免疫还是适应性免疫，Wip1均有重要的调节作用。然而移植免疫领域，Wip1的相关研究还未见报道。我们前期研究发现，较之Wip1+/+鼠，异基因移植心脏在Wip1-/-鼠体内的存活时间显著延长。有趣的是，通过Rapamycin治疗，75%的异基因移植心脏在Wip1-/-鼠体内可以长期存活，并伴随外周血、脾脏及移植物内调节性T细胞（Treg）的显著上调。上述结果提示Wip1参与了移植免疫调控。本课题拟利用Wip1-/-，ATM-/-和Wip1-/-ATM-/-鼠，通过皮片/心脏移植排斥模型，结合体外功能实验及分子生物学方法，深入探讨Wip1调节移植免疫的细胞和分子机制，可为应用Wip1 抑制剂在治疗移植排斥的应用提供理论依据及新思路。

磷酸酶Wip1最初被认为是一种原癌基因，相关研究主要集中于DNA损伤修复及肿瘤的发生调控中。我们的前期研究发现其对免疫细胞尤其是中性粒细胞的发育与功能也具有重要作用，本研究中，我们则首次探索了其在移植免疫中的功能，课题研究结果表明磷酸酶Wip1通过调控适应性免疫系统中最经典的免疫抑制性细胞调节性T细胞的免疫抑制功能，借mTOR及ATM信号通路，影响调节性T细胞的抑制功能，Wip1缺失或使用药物抑制其表达，能显著延长移植物存活，这些结果能够为今后临床开发以Wip1为靶点的免疫抑制药物提供新的思路；此外，我们也探索了固有免疫细胞中同样具有免疫抑制功能的髓源性抑制性细胞（MDSC）在移植免疫耐受中的作用。我们的结果惊喜的发现临床常用的抗炎药物地塞米松能够通过地塞米松受体信号通路，调控MDSC表达趋化因子受体CXCR2，更多地迁移到移植物内，抑制急性免疫排斥；并且趋化而来的MDSC还能对适应性免疫系统中最重要的调节性T细胞发挥调控作用，增加调节性T细胞的数量，共同促进移植物存活时间的延长。