School of Medicine and Population Health, INSIGNEO Institute, and the Bateson Centre (D.P., S.T., S.E.I., J.S.-C.), University of Sheffield, United Kingdom.
National Heart and Lung Institute (D.P., G.M.B.), Imperial College London, United Kingdom.
Circ Res. 2024 Sep 27;135(8):822-837. doi: 10.1161/CIRCRESAHA.123.324054. Epub 2024 Sep 5.
Atherosclerotic plaques form unevenly due to disturbed blood flow, causing localized endothelial cell (EC) dysfunction. Obesity exacerbates this process, but the underlying molecular mechanisms are unclear. The transcription factor EPAS1 (HIF2A) has regulatory roles in endothelium, but its involvement in atherosclerosis remains unexplored. This study investigates the potential interplay between EPAS1, obesity, and atherosclerosis.
Responses to shear stress were analyzed using cultured porcine aortic EC exposed to flow in vitro coupled with metabolic and molecular analyses and by en face immunostaining of murine aortic EC exposed to disturbed flow in vivo. Obesity and dyslipidemia were induced in mice via exposure to a high-fat diet or through Leptin gene deletion. The role of in atherosclerosis was evaluated by inducible endothelial deletion, followed by hypercholesterolemia induction (adeno-associated virus-PCSK9 [proprotein convertase subtilisin/kexin type 9]; high-fat diet).
En face staining revealed EPAS1 enrichment at sites of disturbed blood flow that are prone to atherosclerosis initiation. Obese mice exhibited substantial reduction in endothelial EPAS1 expression. Sulforaphane, a compound with known atheroprotective effects, restored EPAS1 expression and concurrently reduced plasma triglyceride levels in obese mice. Consistently, triglyceride derivatives (free fatty acids) suppressed EPAS1 in cultured EC by upregulating the negative regulator PHD2. Clinical observations revealed that reduced serum EPAS1 correlated with increased endothelial PHD2 and PHD3 in obese individuals. Functionally, endothelial EPAS1 deletion increased lesion formation in hypercholesterolemic mice, indicating an atheroprotective function. Mechanistic insights revealed that EPAS1 protects arteries by maintaining endothelial proliferation by positively regulating the expression of the fatty acid-handling molecules CD36 (cluster of differentiation 36) and LIPG (endothelial type lipase G) to increase fatty acid beta-oxidation.
Endothelial EPAS1 attenuates atherosclerosis at sites of disturbed flow by maintaining EC proliferation via fatty acid uptake and metabolism. This endothelial repair pathway is inhibited in obesity, suggesting a novel triglyceride-PHD2 modulation pathway suppressing EPAS1 expression. These findings have implications for therapeutic strategies addressing vascular dysfunction in obesity.
由于血流紊乱，动脉粥样硬化斑块形成不均匀，导致局部内皮细胞（EC）功能障碍。肥胖会加剧这一过程，但潜在的分子机制尚不清楚。转录因子 EPAS1（HIF2A）在血管内皮中有调节作用，但它在动脉粥样硬化中的作用仍未被探索。本研究探讨了 EPAS1、肥胖和动脉粥样硬化之间的潜在相互作用。
通过体外培养的猪主动脉 EC 在流动条件下的培养，结合代谢和分子分析，以及体内暴露于紊乱血流的小鼠主动脉 EC 的免疫荧光共定位，分析对切应力的反应。通过高脂饮食或瘦素基因缺失诱导小鼠肥胖和血脂异常。通过诱导性内皮细胞 EPAS1 缺失，然后进行高胆固醇血症诱导（腺相关病毒-PCSK9[前蛋白转化酶枯草溶菌素/柯萨奇蛋白酶 9]；高脂饮食），评估在动脉粥样硬化中的作用。
共定位染色显示 EPAS1 在易发生动脉粥样硬化起始的血流紊乱部位富集。肥胖小鼠的内皮 EPAS1 表达明显减少。具有已知抗动脉粥样硬化作用的化合物萝卜硫素可恢复肥胖小鼠的 EPAS1 表达，并同时降低其血浆甘油三酯水平。一致地，甘油三酯衍生物（游离脂肪酸）通过上调负调节因子 PHD2 抑制培养的 EC 中的 EPAS1。临床观察显示，血清 EPAS1 减少与肥胖个体中内皮 PHD2 和 PHD3 的增加相关。功能上，内皮细胞 EPAS1 缺失增加了高胆固醇血症小鼠的病变形成，表明其具有抗动脉粥样硬化作用。机制研究表明，EPAS1 通过正调控脂肪酸处理分子 CD36（分化簇 36）和 LIPG（内皮型脂肪酶 G）的表达来维持内皮细胞增殖，从而保护动脉，增加脂肪酸β氧化。
内皮细胞 EPAS1 通过维持 EC 增殖来减轻紊乱血流部位的动脉粥样硬化，通过摄取和代谢脂肪酸。在肥胖中，这种内皮修复途径被抑制，提示存在一种新的甘油三酯-PHD2 调节途径抑制 EPAS1 的表达。这些发现对解决肥胖相关血管功能障碍的治疗策略具有重要意义。
