Department of Cardiology, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200080, China.
Department of Cardiology, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200080, China.
Atherosclerosis. 2019 May;284:1-10. doi: 10.1016/j.atherosclerosis.2019.02.008. Epub 2019 Feb 22.
Cigarette smoking is an established risk factor for atherosclerosis. Nicotine, the major constituent of cigarettes, mediates the phenotype switching of vascular smooth muscle cells (VSMCs) and contributes to atherogenesis. Recent studies show that autophagy regulates atherogenesis via several pathways. The aim of this study is to determine whether nicotine regulates autophagy and subsequently mediates the phenotypic transition of VSMCs.
Oil Red O and HE staining of aortic sections of ApoE mice showed that nicotine promoted atherosclerosis, and in situ expression of α-SMA indicated the involvement of VSMCs. Western blotting documented that nicotine induced the aorta autophagy. Cultured VSMCs treated with nicotine resulted in the increase of LC3 II-to-LC3 I ratio and the decrease of P62, along with GFP-LC3 puncta assay and transmission electron microscopy, further reflecting nicotine-induced autophagy. In addition, Western blotting and quantitative real-time PCR showed that VSMCs exposed to nicotine underwent changes in the expression of differentiation markers (α-SMA, SM22α and osteopontin), confirming the role of nicotine in VSMC differentiation. Transwell migration and scratch assays demonstrated that nicotine increased the migratory capacity of VSMCs. Finally, nicotine also increased the levels of reactive oxygen species (ROS), as measured by DCFH-DA staining. After respectively inhibiting autophagy (3-MA), oxidative stress (NAC), NF-κB activity (BAY 11-7082, si-p65) and nicotinic acetylcholine receptors (nAChRs, hexamethonium), nicotine-induced autophagy and VSMC phenotype switching were reversed.
Nicotine-induced autophagy promotes the phenotype switching of VSMCs and accelerates atherosclerosis, which is partly mediated by the nAChRs/ROS/NF-κB signaling pathway.
吸烟是动脉粥样硬化的既定危险因素。香烟的主要成分尼古丁介导血管平滑肌细胞（VSMCs）的表型转换，并促进动脉粥样硬化形成。最近的研究表明，自噬通过多种途径调节动脉粥样硬化的发生。本研究旨在确定尼古丁是否调节自噬，并随后介导 VSMCs 的表型转变。
载脂蛋白 E 小鼠主动脉切片的油红 O 和 HE 染色显示，尼古丁促进动脉粥样硬化形成，原位表达的α-SMA 表明 VSMCs 的参与。Western blot 表明，尼古丁诱导主动脉自噬。用尼古丁处理的培养 VSMCs 导致 LC3 II 与 LC3 I 的比值增加，P62 减少，同时 GFP-LC3 斑点测定和透射电子显微镜进一步反映了尼古丁诱导的自噬。此外，Western blot 和定量实时 PCR 显示，暴露于尼古丁的 VSMCs 发生分化标志物（α-SMA、SM22α 和骨桥蛋白）表达的变化，证实了尼古丁在 VSMC 分化中的作用。Transwell 迁移和划痕实验表明，尼古丁增加了 VSMCs 的迁移能力。最后，尼古丁还通过 DCFH-DA 染色增加了活性氧（ROS）的水平。分别抑制自噬（3-MA）、氧化应激（NAC）、NF-κB 活性（BAY 11-7082、si-p65）和烟碱型乙酰胆碱受体（nAChRs，六烃季铵）后，尼古丁诱导的自噬和 VSMC 表型转变被逆转。
尼古丁诱导的自噬促进了 VSMCs 的表型转变，并加速了动脉粥样硬化的形成，这部分是通过 nAChRs/ROS/NF-κB 信号通路介导的。
