Hu Zhaohui, Hui Bo, Hou Xuwei, Liu Ruhui, Sukhanov Sergiy, Liu Xiaohong
Department of Cardiovascular Diseases, Tongji Hospital of Tongji University Shanghai 200065, P. R. China.
Department of Cardiovascular Diseases, Qingdao Municipal Hospital of Qingdao University Qingdao, P. R. China.
Am J Transl Res. 2020 Oct 15;12(10):6559-6568. eCollection 2020.
Macrophage activation and massive foam cell formation are key events in the development of Atherosclerosis (AS). Apurinic apyrimidinic endonuclease 1/Redox factor-1 (APE1) is an enzyme responsible for DNA repair and redox regulation. Recent studies indicate that APE1 is also involved in inflammatory response. We sought to explore its effect on oxidized low-density lipoprotein (oxLDL) induced macrophage activation and foam cell formation.
Human macrophage cell line THP-1 cells were cultured and treated with oxLDL. The mRNA and protein levels of inflammatory markers for macrophage activation were measured. Foam cell formation was detected by Oil red O staining. Meanwhile the major cellular receptors responsible for oxLDL uptake and efflux were detected. Chromatin immunoprecipitation-quantitative real time PCR (ChIP-qPCR) and dual luciferase reporter assays were performed to identify the molecular mechanisms through which APE1 affects macrophage activation and foam cell formation.
Aberrant APE1 expression dramatically decreases the mRNA and protein of oxLDL-induced inflammatory molecules in THP-1 cells, accompanied by significantly inhibited foam cell formation. Western blot assay showed that down-regulation of LOX1, a receptor of oxLDL, is responsible for the inhibitory effect of APE1 on oxLDL induced macrophage inflammation. ChIP-qPCR assay showed that APE1 inhibits binding of the LOX1 promoter to its transcription factor Oct1, leading to suppression of LOX1.
Our data confirm the anti-inflammatory properties of APE1 and for the first-time report that APE1 suppresses foam cell formation from macrophages via the oxLDL receptor LOX1. This finding indicates that APE1 can be a therapeutic target for AS prevention.
巨噬细胞活化和大量泡沫细胞形成是动脉粥样硬化（AS）发展过程中的关键事件。脱嘌呤/脱嘧啶内切酶1/氧化还原因子-1（APE1）是一种负责DNA修复和氧化还原调节的酶。最近的研究表明，APE1也参与炎症反应。我们试图探讨其对氧化型低密度脂蛋白（oxLDL）诱导的巨噬细胞活化和泡沫细胞形成的影响。
培养人巨噬细胞系THP-1细胞并用oxLDL处理。检测巨噬细胞活化炎症标志物的mRNA和蛋白质水平。通过油红O染色检测泡沫细胞形成。同时检测负责oxLDL摄取和流出的主要细胞受体。进行染色质免疫沉淀-定量实时PCR（ChIP-qPCR）和双荧光素酶报告基因检测，以确定APE1影响巨噬细胞活化和泡沫细胞形成的分子机制。
异常的APE1表达显著降低THP-1细胞中oxLDL诱导的炎症分子的mRNA和蛋白质水平，同时显著抑制泡沫细胞形成。蛋白质免疫印迹分析表明，oxLDL的受体LOX1的下调是APE1对oxLDL诱导的巨噬细胞炎症抑制作用的原因。ChIP-qPCR分析表明，APE1抑制LOX1启动子与其转录因子Oct1的结合，导致LOX1的抑制。
我们的数据证实了APE1的抗炎特性，并首次报道APE1通过oxLDL受体LOX1抑制巨噬细胞形成泡沫细胞。这一发现表明，APE1可以成为预防AS的治疗靶点。
