Tim-3信号调控蜕膜Mφ功能促进妊娠维持的分子机制

The tolerance of maternal immune system to embryonic antigens and the normal development of placenta determine the success of pregnancy. The disregulation of maternal-fetal immune would result in pregnancy loss. T cell immunoglobulin mucin (Tim)-3 plays important roles in T cell tolerance and tumor invasive growth. Our preliminary data show that the expression of Tim-3 is distinguished on the macrophage (Mφ) from unexplained miscarriaged compared with that from normal pregnancy. The phenotype of Tim-3+ Mφ is also different from Tim-3- Mφ, and decidual Tim-3+ Mφ is asociated with immune regulation and angiogenesis . These results suggest that Tim-3+ Mφ play important roles in the maternal-fetal crosstalk in human early pregnancy. Our subject will study from the different expression and function of Tim-3 on Mφ at the maternal-fetal interface. We will also investigate the regulatory role of Tim-3+ Mφ in the biological function of trophoblasts and decidual stromal cells, functional development of decidual CD4+ T cells, elucidating the mechanism of maternal-fetal tolerance and placentation. This work will be helpful in the development of new preventive strategies in maternal-fetal disorders such as spontaneous abortion and preeclampsia.

正常妊娠依赖母体对胚胎抗原的免疫耐受及作为“伪肿瘤”胎盘的正常发育，一旦母-胎免疫调节失衡、胎盘形成不良将会导致妊娠失败。T淋巴细胞免疫球蛋白黏蛋白家族分子Tim-3在T细胞耐受与肿瘤细胞侵袭中发挥重要作用。我们初步发现Tim-3分子在正常早孕与自然流产蜕膜巨噬细胞（Mφ）上差异表达，在正常早孕和自然流产母-胎界面Tim-3+Mφ与Tim-3-Mφ具有不同的表型，且信息学分析结果提示蜕膜Tim3+ Mφ在免疫调节及血管生成方面具有重要作用，表明蜕膜Tim3+Mφ在母-胎交互对话中发挥重要调节作用。本课题将以人早孕蜕膜Mφ为主要研究对象，首先解析Tim-3在子宫局部Mφ的表达调控机制，进一步探索蜕膜Tim3+Mφ在母-胎界面功能细胞生物学行为以及母-胎免疫耐受形成中的调节作用，以期有助于解析正常早孕母-胎交互对话机制，并为复发性自然流产、子痫前期等病理性妊娠的防治提供新思路。

本研究发现发现滋养细胞以HLA-C/HLA-G限制性通过直接接触的方式激活Mφ，上调其表面Tim-3的表达。蜕膜Tim-3+Mφ上M1和M2相关分子的表达均高于Tim-3-dMφ。与蜕膜Tim-3-dMφ相比，有669个基因在蜕膜Tim-3+dMφ中上调，其中EPAS1基因排名第六。Tim-3+Mφ以HIF-2α依赖的方式促进滋养细胞侵袭。蜕膜Tim-3+Mφ与Tim-3-Mφ差异调控Naive CD4+T细胞分化，蜕膜Tim-3+Mφ通过IL-4和TGF-β1发挥免疫调节作用，抑制Naive CD4+T细胞产生Th1型细胞因子IFN-γ，促进其向Treg分化。RSA患者与自然小鼠模型均存在Tim-3+Mφ数量表型变化，拮抗Tim-3信号，孕鼠胚胎吸收率增加；过继转输Tim-3+Mφ而非Tim-3-Mφ可缓解Mφ缺失引起的胚胎丢失; 而过继转输Tim-3-Mφ后予以PDGF-AA、VEGF与TGF-Α（均为HIF-2α下游靶基因）可缓解Mφ缺失引起的胚胎丢失。. 在此研究基础上，我们进一步研究发现滋养细胞以HLA-C/HLA-G限制性上调T细胞表面Tim-3/CTLA-4的表达。Tim-3+CTLA-4+T细胞数量和功能对于正常妊娠的维持至关重要。Tim-3的配体Galectin-9参与滋养细胞功能调控促进胎盘形成；而滋养细胞又能分泌HA调控dMφ向M2型分化，诱导母-胎免疫耐受，进一步确定了滋养细胞在母-胎免疫耐受中的主导地位，也为临床治疗复发性流产提供潜在切入点。.