蜕膜免疫细胞交互对话与妊娠免疫耐受机制

Toll-like receptors (TLRs) are present not only on uterine immunopotent cells, but also on trophoblast cells. The number and functional status changed dynamically during pregnancy. Additionally, these cells interact and transduce either negative or positive signals depending on interactions with their immediate microenvironment. These findings imply an active cross-talk between the placenta and local immunity. Harmful signals may disturb feto-maternal tolerance. However, the mechanism remains to be clarified. In the current researches based on our previous findings, we aim to investigate the effect of bacterial and viral infectious agents and their breakdown products, such as CpG or double-strended RNA, on fetuses from immunodeficiency or gene knochout murine dams, and gradually elucidate the mechanism by which decidual macrophages, NK cells and other immunopotent cells cross-talk and the mechanisms by which fetuses are tolerated by maternal immune system in allogeneic pregnancy. Multi-color flow cytometry, magnetic affinity cell sorting, transwell cell culture system and other systems will be used in the researches. It is expected that data in our on-going researches including cell-adoptive transfer experiments will be beneficial to make clear the mechanism of feto-maternal recognition and tolerance and improve the strategies for prevention and treatment on disorders caused by pathogens or other factors during pregnancy, which include unexplained recurrent spontaneous abortions, preterm deliveries, and other disorders.

子宫免疫活性细胞和胎盘滋养层细胞均表达Toll样受体，并且各妊娠阶段蜕膜中免疫活性细胞数量和功能状态呈动态变化特征。这些细胞交互对话，根据所接触的微环境特征而转导有益或有害信号，影响妊娠母-胎耐受。具体机制尚未阐明。本项目拟在多年研究工作基础上，采用多色流式细胞术、磁珠亲和细胞分选术、transwell细胞共培养术和荧光示踪技术等，借助于免疫缺陷或基因缺失小鼠模型和临床蜕膜组织等材料，研究并揭示蜕膜中巨噬细胞和NK细胞等各种免疫细胞交互作用的规律，阐明CpG或双链RNA等特异性配体对蜕膜细胞功能的影响，解析感染因素破坏妊娠母-胎耐受平衡的详细分子机制。预期研究结果将有助于绘制出母-胎界面细胞信息转导网络图，揭示妊娠母-胎识别和耐受机理。利用适当动物模型所开展的细胞过继输注治疗研究结果，将为改进免疫型复发性流产和早产等相关疾病预防和诊治策略，提供科学参考。

正常妊娠时母体对携有父系抗原的胎儿不排斥反而允许其在子宫内生长，即形成母胎免疫耐受。其中，蜕膜免疫细胞群是母-胎免疫耐受的生物学基础，这些细胞的交互作用根据所接触的微环境特征而传导有益或有害的信号，来参与妊娠的维持，但具体机制尚未阐明。TLRs信号是蜕膜局部微环境最重要的刺激信号之一，研究TLRs信号刺激后的蜕膜免疫细胞群的交互作用，对阐明独特的母胎耐受及防御机制具有重要的价值。本项目在国家自然基金强有力的支持下，紧紧围绕计划书中的研究计划展开，并取得了一些重要进展。我们发现巨噬细胞分泌CCL20，参与CCR6+Treg细胞向蜕膜局部的募集及蜕膜局部免疫功能的调控。蜕膜存在 MDSCs 细胞,其粒系亚（G-MDSCs）数量减少与流产的发生有关，G-MDSCs 细胞对 Treg 细胞的调控机制之一是通过 mTGFβ/β-catenin 核转录通路诱导 CD4+CD25-T 细胞产生 Foxp3。人类蜕膜组织 TLR1～TLR10 mRNA 均有表达，且 TLR9 mRNA 在流产蜕膜组织中表达最高，蜕膜 TLR9 的异常表达与 URSA 的发生密切相关；过度活化的 TLR9 信号可以通过内源性凋亡途径-Caspase3/8 信号通路直接诱导蜕膜 Treg 细胞的凋亡，也可以通过激活巨噬细胞分泌TNFα间接促进 Treg 细胞在蜕膜的凋亡。目前对母-胎界面微环境中主要免疫活性细胞交互对话机制所知甚少，对TLRs特异性刺激信号与上述细胞间交互对话的影响所知更少，因此,我们的结果有明显创新性，且进一步丰富了母胎免疫耐受的机理，为相关疾病如复发性流产的防治措施的改进提供实验依据。