内皮Nox4与动脉粥样硬化的关系及调控机制

In atherosclerosis, plaques preferentially develop in arterial regions of oscillatory shear stress. In atherosclerosis-prone regions, we found that endothelial Nox4-based NADPH oxidase was significantly down-regulated while soluble epoxide hydrolase 2 was significantly up-regulated. Nox4 as the major component of NADPH oxidases in endothelium, its relationship with atherosclerosis and the potential mechanisms involved are not clear at all. We found that endothelial Nox4 inversely regulated the expression of soluble epoxide hydrolase 2 and the progress of atherosclerosis. We hypothesized that in atherosclerosis-prone regions, endothelial Nox4 might act as an oscillatory shear stress sensor to up-regulate soluble epoxide hydrolase 2, which leads to endothelial dysfunction and the development of atherosclerosis. In this study, by using cultured endothelial cells and endothelial specific Nox4 transgenic mouse lines, we will explore: (1) the mechanisms of shear stress on regulation of Nox4 expression; (2) the mechanisms of Nox4 on regulation of the expression of soluble epoxide hydrolase 2; (3) whether the impact of Nox4 on endothelial functions and the progress of atherosclerosis is mediated by its regulation on soluble epoxide hydrolase 2; (4) other genes regulated by Nox4 involved in atherosclerosis, to address the relationship between endothelial Nox4 and atherosclerosis and the potential mechanisms involved, which will inform the development of therapeutic interventions to improve atherosclerosis.

动脉粥样硬化斑块易发生在形成震荡剪切力的动脉部位。我们发现在动脉粥样硬化易感部位，内皮NADPH氧化酶4(Nox4)的表达明显降低而可溶性环氧化物水解酶(sEH)的表达明显升高。Nox4是内皮NADPH氧化酶最主要的组分，它与动脉粥样硬化的关系及调控机制目前还不清楚。我们发现内皮Nox4负向调控sEH的表达和动脉粥样硬化的进程。我们推测在动脉粥样硬化易感部位，内皮Nox4可能作为震荡剪切力的感应器上调了sEH的表达，导致内皮功能异常和动脉粥样硬化的发生。利用培养的内皮细胞和内皮特异性Nox4转基因小鼠，本课题通过探讨：(1)剪切力调控Nox4的作用机制；(2)Nox4调控sEH的作用机制；(3)Nox4是否通过对sEH的调控来影响内皮功能和动脉粥样硬化；(4)其他参与内皮Nox4对动脉粥样硬化调控的基因，来阐明内皮Nox4与动脉粥样硬化的关系及调控机制，为改善动脉粥样硬化提供干预靶点。

在动脉粥样硬化易感部位，内皮NADPH氧化酶4(Nox4)的表达明显降低而可溶性环氧化物水解酶(sEH)的表达明显升高。Nox4是内皮NADPH氧化酶最主要的组分，它与动脉粥样硬化的关系及调控机制目前还不清楚。本项目探讨Nox4是否通过对sEH的调控来影响内皮功能和动脉粥样硬化。我们发现内皮Nox4可以负向调控sEH。过表达内皮Nox4下调sEH的表达，抑制炎性反应，改善动脉粥样硬化。内皮Nox4功能障碍上调sEH的表达，促进炎性反应，加剧动脉粥样硬化。sEH的抑制剂TPPU改善内皮Nox4功能障碍引起的炎性反应和动脉粥样硬化。内皮Nox4功能障碍诱导内质网应激。利用4-PBA来抑制内质网应激减少sEH的表达，改善内皮Nox4功能障碍引起的动脉粥样硬化。在内皮细胞上sEH可以正向调控内质网应激。过表达sEH诱导内质网应激，而TPPU可以减轻内皮Nox4功能障碍引起的内质网应激。我们推测动脉粥样硬化易感部位内皮Nox4的表达下降通过诱导内质网应激和上调sEH，促进炎性反应，加速动脉粥样硬化的进程。与内皮细胞Nox4相反，平滑肌Nox4通过正向调控sEH来加速动脉粥样硬化。Nox4是决定SERCA2氧化还原状态的关键酶。我们发现SERCA2的一个关键半胱氨酸的氧化失活诱导内质网应激，上调sEH的表达，加剧心血管疾病。推测Nox4也可以通过对SERCA2的氧化修饰来参与心血管疾病的进程。我们的研究一方面明确了内皮Nox4功能障碍时促进动脉粥样硬化发生的机制，提出了内质网应激和sEH都可以成为动脉粥样硬化干预的靶点，另一方面我们的研究也增加了sEH抑制剂TPPU的动脉粥样硬化临床适应症。