间质干细胞通过wnt信号通路调控B细胞的外周分化治疗抗体介导排斥反应的机制研究

Antibody-mediated rejection (AMR), induced by donor specific antibody (DSA) derived from B lymphocytes, is an important risk factor for renal allograft dysfunction. AMR in kidney transplantation is refractory under current available therapeutic regimens. We have completed and reported the first study in which the efficacy and safety of mesenchymal stem cells (MSCs) on AMR in kidney transplantation was approved (Am J Transplant 2014). The subsequent ex vivo experiments showed that MSCs therapy decreased DSA level and increased the proportion of IL-10(+)regulatory B cells (Bregs). Meanwhile, Wnt5a, a critical protein regulating cell differentiation, was also increased after MSCs treatment. We therefore propose the hypothesis that MSCs can direct peripheral differentiation of B lymphocytes to shift from DSA-secreting plasma cells to IL-10(+)Bregs through Wnt5a signaling pathways, and thus exert therapeutic effect on AMR. Based on our previous studies, we intend to perform both in vitro and in vivo animal experiments to ascertain the effect of MSCs on peripheral differentiation of B cells. Besides, we aim to clarify the critical role of Wnt5a in the process above as well as in the downstream signaling pathway in which it is involved. Furthermore, we are going to uncover the correlation between MSCs-derived Wnt5a and therapeutic effect of MSCs on AMR.This project will uncover the underlying cellular and molecular mechanisms of MSCs therapy on AMR, and provide new theoretical explanations and experimental evidence for an in-depth understanding of the immunomodulatory mechanism of MSCs in transplantation settings.

B细胞产生供体特异性抗体(DSA)介导的排斥反应(AMR)是导致移植肾远期失功的重要危险因素，治疗棘手且疗效不佳。我们首次明确了间质干细胞(MSCs)治疗肾移植AMR患者的疗效和安全性(Am J Transplant. 2014)。进一步体外实验发现，MSCs降低DSA水平且增加IL-10+调节性B细胞(Bregs)比例，同时细胞分化调控蛋白Wnt5a升高。据此提出科学假设：MSCs通过Wnt5a调控B细胞向IL-10+Bregs分化而非向产生DSA的浆细胞分化，从而治疗AMR。在前期基础上，拟通过体内外实验进一步明确MSCs对B细胞外周分化的影响作用，探明Wnt5a在其中的关键作用及参与的下游信号通路，阐明MSCs来源的Wnt5a与其治疗AMR作用的相关性。本项目将揭示MSCs治疗AMR的细胞与分子机制，并为深入认识MSCs的移植免疫调节机制提供新的理论解释和实验依据。

在前期基础上，本课题进一步研究MSCs对B淋巴细胞外周分化特别是CD5+调节性B细胞的影响，并研究Wnt5a在其中的作用及分子机制。成功建立小鼠肾移植抗体介导排斥反应ABMR动物实验模型，结合体外细胞学实验，发现MSCs诱导CD5+调节性B细胞分泌IL-10，抑制wnt信号通路可减少CD5+B细胞IL-10的产生，并发现wnt信号通路可能通过HIF-1α调控CD5+ B细胞的免疫调节能力。本项目资助下还研究了供体来源游离DNA、可溶性CD146和Baff在肾移植ABMR诊断中的辅助作用。课题进展顺利，完成了合同书主要研究任务。以上研究结果发表SCI论文9篇，美国移植学会年会（ATC）口头报告1次并获学会颁发的Young Investigator Award，尚余部分结果在资料整理和撰写论文。