EGFR的激活在促进血流动力学诱导颅内动脉瘤发生中的作用机制研究

Intracranial aneurysm （IA）, the leading cause of subarachnoid hemorrhage, has received great concern due to its high morbidity and disability. A large number of evidences have indicated that vessel remodeling and injury caused by abnormal intravascular hemodynamics played critical roles in IA formation. Phenotypic modulation of vascular smooth muscle cell, which epidermal growth factor receptor (EGFR) involved in, is a key process of vessel remodeling, yet the role of EGFR in the initiation of IA is keeping unclear. In the previous work, we found in rabbit aneurysm model induced by abnormal hemodynamics, corresponding ligands and downstream genes of EGFR were significantly enhanced in VSMCs; in the rat IA model phosphorylation level of EGFR was elevated. As EGFR is also reported to involve in many other vascular diseases, we estimate that it plays an important role in the development of IA. In this project, we will focus on the core question of “hemodynamics→activation of EGFR→initiation of IA” and carry out a series of studies in animal, cell and human level, respectively. Firstly, we will study activation of EGFR in the initiation of IA in the rat model by comparing the results with or without the specific inhibitor. The correlation of hemodynamics with activation of EGFR and phenotypic modulation of VSMCs will then be explored. Finally, the link of hemodynamics with activation of EGFR will be identified in human IA samples. This study aims to clarify the importance of activated EGFR induced by hemodynamics in the initiation of IA and provide theoretical basis for the role of EGFR in the noninvasive treatment of IA.

颅内动脉瘤（IA）是蛛网膜下腔出血的首要病因，因具有高致病率、高致残率等特点而备受关注。大量数据表明其发生与异常血流动力学引起的血管重构和损伤有密切关系。表皮生长因子受体（EGFR）参与的血管平滑肌细胞（VSMC）表型转化是血管重构的重要环节，但其在IA中的作用尚不明确。前期我们在异常血流动力学诱导的动物模型中发现VSMCs中EGFR配体及下游基因有显著升高，EGFR磷酸化水平增强。本项目拟围绕“异常血流动力学→EGFR激活→IA发生”这一关键问题。首先构建异常血流动力学诱导的动物IA模型并通过施加特异性抑制剂研究EGFR的激活在IA发生中的作用；然后在细胞水平研究EGFR的激活水平以及VSMCs表型转化程度与切应力强度的相关性；最后在人IA中证实EGFR激活与血流动力学的相关性。本研究旨在阐明血流动力学诱导EGFR激活在IA发生中的重要性，为EGFR在IA无创治疗策略中应用提供理论依据。

颅内动脉瘤（IA）是蛛网膜下腔出血的主要诱因，因其具有高致病率、高致残率等特点而成为临床治疗的难点。研究表明IA的发生与异常血流动力学引起的病理性血管重构有关。表皮生长因子受体（EGFR）作为调控多种细胞过程的关键分子，在许多疾病的发生中都发挥着重要作用。血管平滑肌细胞（VSMCs）作为血管中膜的重要细胞成分，被报道参与了很多血管疾病的血管重构，研究发现EGFR的激活能调节VSMCs的表型转化。EGFR在IA中的作用目前尚不清楚。本项目的主要研究内容是：人IA标本中证实EGFR的情况激活和VSMC的表型转化情况；动物模型中通过施加特异性抑制剂研究EGFR的激活在IA发生中的作用；细胞水平研究EGFR的激活水平以及VSMCs表型转化程度与切应力强度的相关性。通过这几部分研究，发现EGFR在人IA标本血管壁中显著激活。通过异常血流动力学构建大鼠IA模型，并施加EGFR特异性抑制剂厄洛替尼发现，EGFR在大脑前动脉的血管壁中被激活，而厄洛替尼的使用可显著降低血管重构以及IA的发生率。厄洛替尼还与α-SMA的表达恢复以及p38MAPK、Erk1/2和MMPs的活化降低有关。体外实验中将VSMC和血管内皮细胞（ECs）进行共培养，并施加不同大小的血流动力学负荷刺激，结果显示EGFR在VSMCs中的激活与血管壁切应力的大小有关。厄洛替尼的使用使α-SMA的表达得到部分恢复。此外，细胞实验中还发现细胞因子TNF-α可诱导EGFR活化。综上，本项目的结果提示EGFR的激活在血流动力学诱导的IA形成中起着重要作用，EGFR抑制剂可以减轻大鼠IA形成的程度和VSMC的表型转化。本项目为寻找IA无创治疗的靶点提供了一定的理论支持，具有较高的理论价值和临床意义。