TIMP-3-Wnt/β-catenin通路调控妊娠早期母-胎界面DCs分化的机制研究

The establishment of maternal-fetal tolerance plays an important role in success of pregnancy. Immature dendritic cells (imDCs) accumulate significantly at maternal-fetal interface in early pregnancy, and are regarded as essential regulators of maternal-fetal tolerance. Tissue inhibitor of metalloproteinases (TIMPs) are important regulators in maturation of myeloid immunocytes, and we and other groups have demonstrated that TIMP-3 is strikingly up-regulated during the differentiation from CD14+ monocytes into imDCs, and is closely involved in the regulation of differentiation and function of imDCs (Blood, 2012). TIMP-3 is highly expressed at maternal-fetal interface in early pregnancy, a process in which epigenetic modulation, for example DNA methylation, may be involved. However, the possible roles of TIMP-3 in maternal-fetal tolerance have still not been demonstrated. The activation of Wnt/β-catenin signaling pathway is one of the major events in maturation of myeloid immunocytes; TIMPs, however, inhibit this pathway and thereby interfere with cells differentiation, but their regulation of the function of imDCs was not clear. In this study, we explore the effect of TIMP-3-Wnt/β-catenin signaling pathway on the expansion and function of imDCs at maternal-fetal interface in early pregnancy, and also analysis the potential role of TIMP-3 epigenetic modulation in maternal-fetal immunity. This study will provide important theoretical complements in understanding the establishment of maternal-fetal tolerance, and also provide new strategy for the prevention and treatment of pathological obstetrics.

妊娠早期母-胎免疫耐受的建立是妊娠成功的关键。妊娠局部未成熟树突状细胞（imDCs）数量增多，参与维持母-胎耐受。基质金属蛋白酶抑制剂（TIMPs）在髓系免疫细胞成熟中发挥重要作用，我们及其他课题组均发现TIMP-3在单核向DCs分化过程中被诱导表达，并调控其分化与功能（Blood，2012）。妊娠早期母胎界面TIMPs高表达，可能与启动子区甲基化水平有关，但在免疫耐受中的作用和机制尚不清楚。Wnt/β-catenin通路是髓系免疫细胞成熟的关键通路，TIMPs能致其失活而影响细胞分化，但尚不清楚是否调节imDCs的免疫功能。本研究拟在前期工作基础上，进一步研究TIMP-3-Wnt/β-catenin通路对妊娠早期母-胎界面imDCs扩充及功能的调控，并综合分析TIMP-3表观遗传修饰与母-胎耐受的关系。本项目将为揭示母-胎耐受的形成及维持机制提供重要理论依据，为防治病理性妊娠提供新策略。

妊娠过程中，未成熟树突状细胞（imDCs）在母胎界面的浸润数量显著增多，在母胎耐受中发挥重要作用，但其扩充来源目前尚不清楚。基质金属蛋白酶抑制剂3（TIMP-3）在包括树突状细胞在内的髓系免疫细胞的分化成熟过程中发挥重要作用。妊娠局部存在TIMP-3的高表达。本研究探究了妊娠微环境对树突状细胞成熟及TIMP-3表达的调控作用及相关机制，发现蜕膜基质细胞上清或间接共培养均显著促进imDCs表面TIMP-3的表达，并影响DCs表型和细胞因子分泌谱。进一步研究发现蜕膜基质细胞分泌的多种细胞因子参与TIMP-3的表达调控。此外，人妊娠早期滋养细胞系HTR-8/SVneo也对DCs的表型和功能存在显著影响，并促进CD14+单核细胞向髓系来源抑制细胞（MDSC）的分化。妊娠微环境中的特征性因子与妊娠结局密切相关，某些特殊因子表达异常可导致病理性妊娠的发生。本研究发现妊娠早期高瘦素微环境可与体外环境中促进人妊娠滋养细胞的侵袭活性；而子痫前期胎盘组织中补体反应基因-32（RGC32）表达显著下调，并影响滋养细胞的侵袭活性。妊娠早期胎盘植入过程与肿瘤细胞的侵袭行为存在相似性，本研究探究了巨噬细胞集落刺激因子（M-CSF）在人结肠癌细胞与肿瘤浸润巨噬细胞相互作用中扮演的重要角色。总之，本研究从多角度探究了妊娠微环境对局部浸润免疫细胞功能活性的调控，尤其首次发现TIMP-3在蜕膜基质细胞调控DCs成熟及活性中发挥的重要作用，为母胎耐受及病理性妊娠相关机制的理解做出了有价值的补充。