可溶性Axl调控血管内皮损伤在重度子痫前期中的作用及机制研究

Preeclampsia, especially the severe one, is a major cause of maternal and perinatal mortality and morbidity. Although the exact pathogenesis of this disorder remains largely elusive, it is certain that vascular endothelial dysfunction is the key event of this pregnancy-specific disease. Our preliminary studies have demonstrated that the Axl was observed in placental vascular endothelial cells in both severe preeclampsia and healthy pregnancy by immunohistochemical staining; furthermore in severe preeclampsia, plasma sAxl(a soluble form of Axl) concentration and Axl level in placenta homogenates were elevated significantly, even correlated with certain important clinical parameters of the disease. It has been confirmed that Axl can bind to its ligand growth arrest specific protein 6(Gas6) with high affinity, emerging as an important regulator for maintaining vascular permeability and integrity. However, abnormally elevated sAxl in plasma with the ability to inhibit the Gas6-Axl pathway via bonding to Gas6 leads to vascular endothelial dysfunction, strongly suggesting its pivotal role in the pathogenesis of severe preeclampsia. Therefore, this project is designed to verify the specific role of sAxl in the pathogenesis of severe preeclampsia: firstly, a case control study is performed to identify the relationship between the plasma sAxl level and some of key molecules involved in the placental vascular endothelial dysfunction; secondly, an experiment in vitro is conducted to examine the induced the placental vascular endothelial dysfunction and its mechanism via observing the biologic behavior changes of human placental microvascular endothelial cells after using exogenous sAxl; thirdly, an animal model is established to investigate the classical manifestations of preeclampsia and its mechanism after overexpression of sAxl in mice; and lastly, a prospective cohort study is designed to determine the changes of plasma sAxl concentration during the progress of gestation and the development of preeclampsia. Overall, the results of the present project will not only explicit the exact mechanism of sAxl in the involvement of severe preeclampsia, but also provide more evidence on developing a new target for prevention and management of this disease.

重度子痫前期是严重威胁母儿健康的妊娠期疾病，发病机制亟待阐明，目前公认血管内皮损伤是其发病中心环节。前期研究发现重度子痫前期血浆sAxl和胎盘匀浆Axl均显著升高，更重要的是与该病的重要临床指标相关。已有研究证实膜Axl与Gas6结合参与调控血管内皮生理功能，血浆过量sAxl可与Gas6结合抑制Gas6-Axl下游信号通路，致血管内皮生理功能调控障碍，强烈提示血浆sAxl升高可能是参与重度子痫前期发病的关键机制。本项目拟从sAxl这一全新角度入手，研究血浆sAxl与胎盘血管生成及损伤关键分子的关系、体外细胞学研究sAxl对胎盘微血管内皮细胞的损伤作用及机制、动物体内应用外源sAxl导致子痫前期样改变及机制，揭示sAxl通过调控血管内皮损伤在重度子痫前期中的作用及机制；并通过前瞻性队列研究，探索血浆sAxl与妊娠进展及结局关系。不仅将丰富和完善重度子痫前期发病机制研究，也为其防治提供新思路。

重度子痫前期是严重威胁母儿健康的妊娠期疾病，血管内皮损伤是其发病中心环节。本项目探讨了血浆可溶性Axl（sAxl）与胎盘血管生成及损伤关键分子的关系；通过体外细胞学实验，研究了sAxl对血管内皮细胞的损伤作用及机制；通过建立动物模型，探索了sAxl导致动物子痫前期样的病理改变及机制；同时，探究了血浆sAxl与妊娠进展及疾病发生发展和预后的关系。研究发现：重度子痫前期患者血浆sAxl 浓度显著高于正常妊娠妇女，血浆sAxl 浓度不仅与血压、24 小时尿蛋白、母体尿液病理管型浓度和新生儿出生体重有显著相关性，而且与血浆 sFlt-1、胎盘 VCAM-1、ICAM-1 及 eNOS 等表征血管内皮功能的指标存在相关性。外源性人重组 sAxl蛋白可以抑制血管内皮细胞的增殖、增加细胞毒性诱导内皮细胞凋亡，抑制血管内皮细胞的成管能力，增加内皮细胞的通透性，减弱其屏障功能，影响 eNOS、ICAM-1 及 MCP-1 mRNA 的表达；此外，sAxl 还可能通过影响内皮细胞中 Akt、Grb2、mTOR 及 p-p70S6K 等多种信号分子的表达及活化从而影响内皮细胞的生物学行为及功能。通过建立大鼠动物模型，证实了经Ad-sAxl干预的孕鼠血压及尿蛋白均随妊娠进展而升高，胎儿宫内生长受限，孕鼠血ALT、LDH及Cr显著升高，其肾脏肾小球血管基本不表达CD31荧光；异常增高的 sAxl可引起大鼠血浆及胎盘中 sFlt-1、Gas6、eNOS 、VCAM-1 及 ICAM-1 等与血管内皮功能密切相关的因子的表达改变，提示在实验动物体内 sAxl 同样能够影响血管内皮细胞的功能，并导致其肾脏发生形态结构改变。本项目的结果丰富和完善了sAxl调控血管内皮细胞的损伤机制以及在重度子痫前期发病机制中的作用，为sAxl 作为子痫前期的临床预测指标提供实验依据，具有重要的科学意义。