Periostin基因介导血管紧张素Ⅱ促巨噬细胞源性泡沫细胞形成和动脉粥样病变的机制研究

Macrophage foam cell formation is a key event during the development and progression of atherosclerosis. Angiotensin II (Ang II) has been shown to promote the formation of foam cells, yet the underlying mechanisms remain incompletely understood. Our previous work demonstrated that Ang II has the ability to induce the expression of periostin in THP-1 macrophages and that neutralization of periostin impairs Ang II-induced foam cell formation . Given that both Ang II and periostin provide similar effects on atherogenesis, we hypothesized that periostin acts as a key downstream mediator of Ang II and is involved in the regulation of foam cell formation and atherosclerosis. To test this hypothesis, in this project we attempted to clarify the mechanisms by which Ang II induces the expression of periostin in macrophages. We performed loss- and gain-of function experiments to determine the roles of periostin in Ang II-induced foam cell formation. We also sought to identify the functional mediators of periostin in foam cell formation. Finally, in-vivo studies were performed to confirm the roles of periostin in Ang II-induced atherosclerosis. This project would identify a novel mediator of Ang II in the promotion of atherosclerosis and provide a potential therapeutic target for prevention and treatment of atherosclerosis.

巨噬源性泡沫细胞形成是动脉粥样硬化（AS）发生发展的关键环节。血管紧张素Ⅱ（AngⅡ）对泡沫细胞形成具有促进作用，然而，相关机制仍不清楚。本课题组前期工作显示，Ang II诱导巨噬细胞periostin的表达；抑制periostin通路破坏Ang II促泡沫细胞形成效应。基于Ang II和periostin都具有促AS活性，我们推测“Periostin作为Ang II的一个重要效应因子参与泡沫细胞形成和AS发展”。为了检验这一假说，本项目拟：深入揭示Ang II诱导periostin表达的机制；阐明periostin在Ang II促泡沫细胞形成中的介导作用；鉴定periostin下游效应基因并且确定它们对巨噬泡沫细胞的调控功能；在体内模型中确认periostin对Ang II促AS发生的调控作用。本课题旨在鉴定新的介导Ang II调控AS发生的效应基因，为AS的防治提供潜在的靶点。

动脉粥样硬化性疾病严重威胁人类的健康。巨噬源性泡沫细胞形成是动脉粥样硬化（AS）发生发展的关键环节，大量研究证明，血管紧张素Ⅱ（AngⅡ）对泡沫细胞形成具有促进作用，然而，相关机制仍不清楚。. 本课题组详细阐明AngII诱导periostin的机制，结果显示AngII可以显著增加巨噬细胞periostin的表达；当阻断NF-κB活性时，AngII诱导periostin的效应会被显著抑制。染色质免疫沉淀实验结果证实，AngⅡ可以增强NF-κB p65在periostin启动子区的富集。进一步明确periostin对巨噬细胞胆固醇摄取、胞内胆固醇酯化及胆固醇外排的调控作用，确定periostin 在AngII促泡沫细胞形成中的介导作用；并揭示它们对巨噬泡沫细胞形成的调控作用；通过基因过表达和沉默periostin，结果发现，Ang II处理可显著增加THP-1巨噬细胞的脂质积累，而沉默periostin可阻断Ang II对泡沫细胞形成的影响。沉默periostin可减弱Ang II诱导的脂质积累并增强胆固醇流出，相反，重组periostin基因过表达增强了Ang II诱导的巨噬细胞泡沫细胞的形成，periostin基因沉默明显抑制了Ang II诱导的巨噬细胞泡沫细胞的形成。并在动物模型中进一步确认periostin对AngII促AS发生的调控作用，结果显示，在高脂诱导的ApoE-/-小鼠动脉粥样硬化模型中，注射periostin沉默重组慢病毒及过表达慢病毒可以抑制动脉粥样病变及巨噬细胞聚集，并影响胆固醇相关因子的表达。. 本课题首次阐明Periostin作为Ang II的一个重要效应因子参与Ang II对巨噬细胞胆固醇稳态及泡沫细胞形成的调控作用，为认识其调控AS发生提供新的视角，并且为AS的防治提供潜在的靶点。