缺氧诱导的合体滋养细胞胞外体过度分泌的调控机制研究

Preeclampsia (PE) is one of the most significant obstertric diseases that are harmful to the health of both pregnant women and their fetuses. The underlying mechanism of PE is not clearly understood. Excessive secretion of the placental syncytiotrophoblast exosome (STBE) into maternal circulation can result to local inflammation and systemic immune imbalance. The underlying mechanism of excessive secretion of STBE is still unknown. But the cellular processes of STBE release decided that the fusion of multivesicular body (MVB) with plasma membrane is considered to play a crucial role in STBE release. It is indicated that R6IP1/Rab11 are important regulatory molecules in this link. The preliminary research of our group indicated that hypoxia can increase the secretion of STBE and activating HIF-1α which regulates the expression of R6IP1. Thus in this program, on the basis of previous investigations, we will identify the expressive and activated characteristics of R6IP1/Rab11, along with the fusion of MVB with plasma membrane of syncytiotrophoblast (STB) in PE placentas at first. And then, applying the explanting placental tissue in culture, we will investigate the effects of placental hypoxia on the expression of proteins in HIF-1α/R6IP1/Rab11 pathway, fusion of MVB and secretion of STBE. Finally, we will further utilize the trophoblast fusing model associating the RNA interference technique to verify our scientific hypothesis “HIF-1α/R6IP1/Rab11 regulating the placental hypoxia induced excessive secretion of STBE”, and clear out its potential mechainsm. This program is assumed to provide direct experimental evidences and feasible targets for developing new clinical treatment strategy on PE.

子痫前期（PE）严重威胁母胎健康但发病机制不明。胎盘滋养细胞（STB）过度分泌合体滋养细胞胞外体（STBE）入母血导致局部炎症反应和全身免疫失衡是PE发病的重要因素。STBE过度分泌的机制尚不清楚，但STBE释放的细胞学过程决定了多泡体（MVB）与胞膜融合是其中的关键环节，而R6IP1/Rab11可能是调控该环节的重要分子。本课题组预研表明缺氧可引发STBE分泌增多，并激活HIF-1α，后者可调控R6IP1的表达。在此基础上，本项目拟先明确PE胎盘中R6IP1/Rab11表达及MVB与胞膜融合的特点；再用胎盘体外培养探讨缺氧对HIF-1α/R6IP1/Rab11通路、MVB融合和STBE脱落的影响；最后用滋养细胞融合模型结合RNA干扰技术，验证HIF-1α/R6IP1/Rab11通路调控胎盘缺氧诱导的STBE过度分泌的假设，并明确其可能机制，为PE临床治疗的新策略提供可行靶点和实验依据。

本研究结果证实PE孕妇外周血中STBE的浓度显著高于正常妊娠孕妇，该病理现象可能是PE发病的重要基础。PE患者及正常孕妇的胎盘组织在缺氧条件下释放STBE的含量较常氧条件下均增多，再次证实缺氧是诱导STBE分泌增多并致病的重要病理生理机制。在缺氧条件下胎盘组织和合体滋养细胞模型中HIF-1α/R6IP1/Rab11通路的各种分子的表达水平均呈上升趋势，而在常氧条件下Rab11蛋白的表达量无明显差异，提示HIF-1α/R6IP1/Rab11通路是缺氧诱导的STBE增多的关键信号通路。HIF-1α的改变主要影响Rab11a的分子表达，因此，Rab11a可能是执行缺氧引起STBE过度释放的开关分子。