Department of Neurology, Taihe Hospital, Hubei University of Medicine, Shiyan, China.
Department of Neurology, Aerospace Center Hospital, No. 15, Yuquan Road, Haidian District, Beijing, 100049, China.
Biochem Biophys Res Commun. 2018 Sep 10;503(3):1897-1904. doi: 10.1016/j.bbrc.2018.07.133. Epub 2018 Aug 7.
Atherosclerosis is a complex chronic inflammatory disease that is characterized by the formation of lipid-rich plaques on the inner walls of the arteries. Inactive rhomboid protein 2 (iRhom2) was recently determined as a necessary regulator for the shedding of tumor necrosis factor-alpha (TNF-α) in immune cells. In the present study, we aimed to explore the effects of iRhom2 on the inflammatory response and oxidative stress induced by low-density lipoprotein (ox-LDL) in RAW264.7 and THP-1-derived macrophages. The expression levels of iRhom2 were also investigated in apolipoprotein E knockout (ApoE) mice fed a high-fat diet (HFD). iRhom2 was significantly induced by ox-LDL in macrophages, as confirmed by Western blotting and RT-qPCR analysis. Furthermore, iRhom2 knockdown showed significant suppressive effects on the activation of ox-LDL-induced RAW264.7 and THP-1-derived macrophages through reducing TACE and TNFR2 expressions, and the inactivation of the IκBα/NF-κB signaling pathway. A reduction in reactive oxygen species (ROS) generation, malondialdehyde (MDA) levels, and nitric oxide (NOX) activity and an increase in glutathione peroxidase (GSH-Px) activity were determined in the absence of iRhom2 expression. In addition, the NF-E2 related factor-2 (Nrf-2)/heme oxygenase-1 (HO-1) pathway was also upregulated in ox-LDL-treated macrophages subjected to iRhom2 inhibition. Moreover, suppression of iRhom2 expression inactivated PI3K/AKT pathway activation, contributing to ROS reduction in ox-LDL-stimulated macrophages. iRhom2 was also significantly expressed in ApoE mice fed HFD. Finally, we observed increased serum levels of TNF-α, TNFR1, and TNFR2 in patients with coronary artery atherosclerosis as compared to healthy volunteers. In conclusion, our findings suggested that iRhom2 played a key role in the pathogenesis of atherosclerosis, and that iRhom2 might be a potential therapeutic target against atherosclerosis.
动脉粥样硬化是一种复杂的慢性炎症性疾病，其特征是动脉内壁形成富含脂质的斑块。最近发现，不活跃的菱形蛋白 2（iRhom2）是免疫细胞中肿瘤坏死因子-α（TNF-α）脱落的必要调节因子。在本研究中，我们旨在探讨 iRhom2 对低密度脂蛋白（ox-LDL）诱导的 RAW264.7 和 THP-1 衍生巨噬细胞炎症反应和氧化应激的影响。还研究了载脂蛋白 E 敲除（ApoE）小鼠高脂饮食（HFD）喂养时 iRhom2 的表达水平。Western blot 和 RT-qPCR 分析证实，ox-LDL 可显著诱导巨噬细胞中 iRhom2 的表达。此外，iRhom2 敲低通过降低 TACE 和 TNFR2 表达以及抑制 IκBα/NF-κB 信号通路，对 ox-LDL 诱导的 RAW264.7 和 THP-1 衍生巨噬细胞的激活具有显著的抑制作用。在没有 iRhom2 表达的情况下，观察到活性氧（ROS）生成、丙二醛（MDA）水平和一氧化氮合酶（NOX）活性降低，谷胱甘肽过氧化物酶（GSH-Px）活性升高。此外，ox-LDL 处理的巨噬细胞中 NF-E2 相关因子-2（Nrf-2）/血红素加氧酶-1（HO-1）途径也被上调，抑制 iRhom2 表达。此外，抑制 iRhom2 表达可使 PI3K/AKT 通路失活，导致 ox-LDL 刺激的巨噬细胞中 ROS 减少。iRhom2 在 HFD 喂养的 ApoE 小鼠中也有明显表达。最后，与健康志愿者相比，我们观察到冠心病动脉粥样硬化患者血清 TNF-α、TNFR1 和 TNFR2 水平升高。综上所述，我们的研究结果表明，iRhom2 在动脉粥样硬化的发病机制中起关键作用，iRhom2 可能是一种潜在的抗动脉粥样硬化治疗靶点。
