IRF-1介导的内皮细胞功能失调在动脉粥样硬化中的作用

Endothelial dysfunction plays a critical role in the pathogenesis of atherosclerosis. Accumulation of metabolic intermediates of lipid inside endothelial cells caused by hyperlipidemia usually induces endoplasmic reticulum stress, mitochondrial injury and autophagy, which may lead to inflammation and cell death. The transcription factor IRF-1 can activate transcription of key genes involved in inflammation, apoptosis and autophagy. It can also target Vcam-1 gene and promote its expression in endothelial cells. However, it remains unknown whether or not IRF-1 plays a role in hyperlipidemia-induced atherosclerosis. In our previous study, we have found in the human aortic endothelial cells high-fat diet causes endoplasmic reticulum stress, which upregulates VCAM-1 expression and monocyte adhesion via activation of IRF-1(Circ Res；PlosOne). Preliminary studies have suggested that IRF-1 is implicated in oxLDL-induced endothelial apoptosis and cytokine expression. Moreover, it decreases autophagy and degradation of oxLDL in endothelial cells. This project aims to 1) further investigate the reciprocal regulation between IRF-1, ER/Mit stress and autophagy in the setting of metabolic stress, and how they synergize in mediating endothelial dysfunction; and 2) to seek direct evidence for the pathophysiological role of IRF-1-mediated endothelial dysfunction in atherosclerosis by using apoE and endothelium-specific Irf-1 double knockout mouse model of atherosclerosis. The findings obtained from this project would make novel contribution to the understanding of how risk factors cause cardiovascular diseases.

内皮细胞（EC）功能失调是引发动脉粥样硬化（As）的关键环节。高脂血症导致脂质在EC的堆积可触发内质网（ER）和线粒体（Mit）应激及自噬，严重时可导致EC炎症甚至死亡。转录因子IRF-1可调控炎症、凋亡及自噬关键基因的表达并可转录激活EC中Vcam-1。然而，其在高脂血症导致As中的作用不明。申请人在探讨脂代谢异常导致EC损伤机制的前期研究中，发现ER应激可上调IRF-1而诱导VCAM-1表达及单核细胞粘附(Circ Res)。新近预实验提示IRF-1参与oxLDL诱导的EC凋亡及细胞因子表达，并影响自噬。本课题将深入研究IRF-1与ER/Mit应激及自噬之间的相互调控在EC损伤中的协同作用，并以ApoE-/-小鼠为As模型，采用EC特异基因敲除策略，阐明IRF-1介导的EC功能失调在As中的作用，提出心血管疾病危险因素导致As的分子机制新假说。

氧化修饰的脂质堆积导致的内皮细胞（EC）炎症与死亡是动脉粥样硬化（As）发生的始动环节。大量文献报道转录因子IRF-1可调控炎与细胞凋亡，然而IRF-1在高脂血症导致As中的作用不明。本课题研究了促As因子对内皮IRF-1活性的调控，IRF-1对EC炎症与凋亡的作用；考察了IRF-1活性与线粒体应激的相互调控，并采取组织特异性基因敲除策略，以高脂饲料喂养ApoE-/-小鼠诱导As模型，研究了IRF-1介导的EC功能失调在As中的作用。结果显示：促As因子氧化LDL（oxLDL）上调人主动脉内皮细胞（HAEC）中IRF-1的表达与转录活性。敲降IRF1虽然增加HAEC线粒体膜电位，但却增加线粒体ROS含量及Caspase-3活性。进一步研究显示敲降IRF1显著降低oxLDL诱导的细胞焦亡与炎症。EC特异敲除Irf1明显缓解ApoE-/-小鼠主动脉As的严重程度。本研究阐明了IRF-1通过促进炎症而参与EC功能失调及As发生发展。