Endoglin-BMP9途径维护血管内皮完整性调控急性肺损伤的分子机制

Acute lung injury (ALI) is one of the major mortalities in pulmonary emergency medicine. The molecular mechanisms involved in ALI are complex and remains a very hot topic in clinical research. Researchers now believe that pathological changes in the structure and function of pulmonary endothelium play a pivotal role in ALI. However, the detailed mechanism is elusive. Previous reporters suggested that sphingosine 1-phosphate receptor 1 (S1pr1) is essential for endothelial homeostasis. Indeed, our preliminary data indicate that endothelial S1pr1 is required for maintaining normal structure and function of vasculature. Lung vessels are leaky in endothelial cell (EC)-specific knockout of S1pr1 mice. We analyzed the difference of cell surface proteins between the wild type and knockout EC and discovered that expression ofendoglin (Eng), a glycoprotein regulate angiogenesis and is enriched in EC, was diminished on the knockout EC. Moreover, inhibition of Eng signaling has similar vascular phenotype as that of S1pr1, suggesting Eng is a downstream effector of S1pr1. Therefore, we hypothesize that Eng is indispensible for endothelial integrity and it may regulate progress of ALI. In this proposal, we will use genetic and biochemical approaches to investigate whether Eng and its putative ligand BMP9 regulate vascular integrity in vivo and in vitro. The importance of Eng-BMP9 pathway will be also studied in animal mode of ALI. To our best acknowledge, Eng or BMP9 has not been implicated in the physiopathology of ALI in literature so far. Completion of this proposal will demonstrate a novel role of Eng in regulating vascular integrity and may provide new targetsor ideas for further research on vascular integrity and ALI.

急性肺损伤（ALI）死亡率高、发病机制复杂，肺血管内皮功能和结构受损是其发生发展的重要因素。S1pr1是维护血管内皮完整性的必需受体。我们前期研究发现S1pr1 敲除小鼠肺血管内皮完整性严重受损，对比分析野生型和基因敲除小鼠的内皮细胞表面蛋白,发现内皮糖（Endoglin，Eng）的表达存在明显差异。Eng是血管发育和成熟的重要因素，是否与血管内皮完整性密切相关呢？我们假设：Eng能维护血管内皮的完整性，干预和改变Eng使血管内皮完整性受损，调控ALI的发生和发展。利用基因敲除、siRNA 、慢病毒转染等技术，构建多种离体细胞和ALI动物模型，研究Eng、BMP9 对血管内皮细胞完整性及ALI的影响，并探讨其调控机制。阐明Endoglin-BMP9途径维护肺血管内皮完整性调控ALI。本研究首次分析Eng与肺血管内皮完整性的关系及在ALI中的作用，将为ALI的研究提供新的思路和靶点。

急性肺损伤（ALI）死亡率高、发病机制复杂，肺血管内皮功能和结构受损是其发生发展的重要因素。S1pr1是维护血管内皮完整性的必需受体。endoglin是血管发育和成熟的重要因素。我们假设：endoglin能维护血管内皮的完整性，干预和改变endoglin使血管内皮完整性受损，调控ALI的发生和发展。我们发现S1P通过ERK信号通路调节细胞膜表面endoglin表达来调控Smad信号通路；建立S1Pr1-ECKO、S1Pr1-high小鼠模型，发现小鼠肺脏内皮细胞膜上endoglin的表达需要S1Pr1，用S1Pr1特异性抑制剂、激动剂预处理内皮细胞及构建S1Pr1高表达MS1，发现S1Pr1通过细胞膜上endoglin表达调控Smad信号通路；发现抑制S1P-S1Pr1信号通路后肺脏及气管组织的血管通透性增加，肺部炎症反应加剧。此外，建立肝脏异位表达sEng小鼠模型，发现Eng信号通路促进在体组织血管生成。我们的研究初步阐明了Endoglin-BMP9途径维护血管内皮完整性，并调控急性肺损伤的分子机制，启发了新的急性肺损伤研究思路和方向。