FoxO3介导的自噬缺失导致dNK细胞归巢及发育异常在子痫前期发病中的作用机制研究

Defective vascular remodeling in placenta is the key factor to the pathogenesis of preeclampsia (PE). Extravillous trophoblast cells (EVT) play an essential role at the onset of vascular remodeling by expressing CXCL12, which can exhibit chemotactic activity on natural killer cells (NK cells). Subsequently, NK cells are attracted to uterine decidua and become decidua nature kill cells (dNK cells). Researchers have identified that FoxO3 is associated with Bnip3-mediated-mitophagy. Meanwhile, our previous study has indicated that the expressions of FoxO3 and Bnip3 are downregulated, mitochondrial autophagy induced by Bnip3 is reduced significantly, CXCL12 secreted by EVT is compromised, and dNK cell population is declined in PE disease. Therefore, We hypothesize that the downregulation of transcription factor FoxO3 can induce the dysfunction of Bnip3-mediated-mitophagy in EVT leading to oxidative damage. As a consequence, chemotactic factor CXCL12 secreted by EVT is disrupted, which in term downregulate chemotactic activity in NK cells. These result in the impairment of immune homeostasis of the maternal-fetal interface, disruption of the placental superficial nidation, and defected vascular remodeling, which leads to the commencement of PE. To provide new insight into the pathogenesis of PE, we will apply numerous approaches such as molecular biology, subcellular proteomics, and genetic engineering on cell-tissue-animal models to further verify our hypothesis.

胎盘血管重铸障碍是子痫前期(PE)发病关键点。绒毛外滋养细胞(EVT)通过表达CXCL12调控NK细胞向蜕膜趋化，并驯化成蜕膜NK(dNK)细胞，在血管重铸中发挥始动作用。研究发现FoxO3与Bnip3介导的线粒体自噬有关，课题组前期在PE中证实FoxO3、Bnip3表达降低，Bnip3介导的线粒体自噬明显下降，EVT分泌CXCL12不足，dNK细胞减少。我们推测：EVT中转录因子FoxO3表达下调，使Bnip3介导的线粒体自噬异常，进而加重氧化应激损伤，造成EVT自身功能障碍，趋化因子 CXCL12表达减少，NK细胞向蜕膜归巢异常、dNK细胞驯化不良，打破母胎免疫稳态，发生胎盘浅着床和血管重铸障碍，导致PE。项目拟在细胞、组织及小鼠模型水平上应用分子生物学、亚细胞器蛋白质组学及基因工程等方法，从“细胞-胎盘组织-整体”全面验证该假说，将为深入研究PE的发病机制提供新思路。

1子痫前期是威胁产妇和胎儿的妊娠期特有性临床疾病，以严重的高血压，蛋白尿，肝功能异常，胎儿生长受限等临床症状为显著特点。叉头盒O3a蛋白(forkhead box O3a protein, FoxO3a)已被报道调控肿瘤的侵袭和迁移，但其分子机制及其在滋养细胞侵袭和迁移入子宫中的作用尚不清楚，滋养细胞侵袭迁移等功能受损将导致妊娠不良后果。同时妊娠过程中，类似于移植物的半同种异源胎儿，却不会收到母体免疫系统的攻击和排斥。在这个过程中母胎界面的精细免疫调控是保障正常妊娠的必备条件。蜕膜中免疫细胞70%为CD56brightCD16-的NK细胞，在母胎界面免疫调控中发挥主要作用。dNK细胞功能失调将会导致多种妊娠不良后果，如子痫前期，复发性流产，妊娠期糖尿病等。本研究旨在探讨FoxO3a 在滋养细胞发育和胎盘相关妊娠并发症中的作用及其可能的机制，以及CD39和CD73对蜕膜自然杀伤(dNK)细胞和胎儿绒毛外滋养层(EVT)细胞的调控。研究发现FoxO3a在子痫前期胎盘中表达下调，磷酸化水平增高，细胞表型检测，转录组及代谢组学联合分析表明FoxO3a的敲降将导致滋养细胞的功能障碍，主要表现在侵袭、迁移功能上；同时抑制dNK细胞上的CD39能够将dNK细胞转化为高毒性和低细胞凋亡的活化状态，减低滋养细胞侵袭能力，母胎界面免疫失衡，从而导致妊娠不良结局。