Department of Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ (J.L., L.H., J.H., L.T.T.L., H.W.).
Department of Physiology (W.D.C.), Temple University School of Medicine, Philadelphia, PA.
Arterioscler Thromb Vasc Biol. 2021 Feb;41(2):839-853. doi: 10.1161/ATVBAHA.120.315556. Epub 2020 Dec 31.
Electronic cigarette (e-cig) use has recently been implicated in promoting atherosclerosis. In this study, we aimed to investigate the mechanism of e-cig exposure accelerated atherosclerotic lesion development. Approach and Results: Eight-week-old ApoE mice fed normal laboratory diet were exposed to e-cig vapor (ECV) for 2 hours/day, 5 days/week for 16 weeks. We found that ECV exposure significantly induced atherosclerotic lesions as examined by Oil Red O staining and greatly upregulated TLR9 (toll-like receptor 9) expression in classical monocytes and in the atherosclerotic plaques, which the latter was corroborated by enhanced TLR9 expression in human femoral artery atherosclerotic plaques from e-cig smokers. Intriguingly, we found a significant increase of oxidative mitochondria DNA lesion in the plasma of ECV-exposed mice. Administration of TLR9 antagonist before ECV exposure not only alleviated atherosclerosis and the upregulation of TLR9 in plaques but also attenuated the increase of plasma levels of inflammatory cytokines, reduced the plaque accumulation of lipid and macrophages, and decreased the frequency of blood CCR2 (C-C chemokine receptor type 2) classical monocytes. Surprisingly, we found that cytoplasmic mitochondrial DNA isolated from ECV extract-treated macrophages can enhance TLR9 activation in reporter cells and the induction of inflammatory cytokine could be suppressed by TLR9 inhibitor in macrophages.
E-cig increases level of damaged mitochondrial DNA in circulating blood and induces the expression of TLR9, which elevate the expression of proinflammatory cytokines in monocyte/macrophage and consequently lead to atherosclerosis. Our results raise the possibility that intervention of TLR9 activation is a potential pharmacological target of ECV-related inflammation and cardiovascular diseases.
电子烟（e-cig）的使用最近被牵连到促进动脉粥样硬化。在这项研究中，我们旨在研究电子烟暴露加速动脉粥样硬化病变发展的机制。
8 周龄载脂蛋白 E （ApoE） 小鼠喂食正常实验室饮食，每天暴露于电子烟蒸气（ECV）2 小时，每周 5 天，共 16 周。我们发现，ECV 暴露显著诱导动脉粥样硬化病变，如油红 O 染色所示，并大大上调了经典单核细胞和动脉粥样硬化斑块中的 TLR9（ toll-like receptor 9）表达，后者在吸电子烟者的股动脉粥样硬化斑块中得到了 TLR9 表达增强的证实。有趣的是，我们发现 ECV 暴露小鼠血浆中的氧化线粒体 DNA 损伤显著增加。在 ECV 暴露前给予 TLR9 拮抗剂不仅减轻了动脉粥样硬化和斑块中 TLR9 的上调，还减轻了炎症细胞因子血浆水平的增加，减少了脂质和巨噬细胞的斑块积累，并降低了血液 CCR2（ C-C 趋化因子受体 2）经典单核细胞的频率。令人惊讶的是，我们发现从 ECV 提取物处理的巨噬细胞中分离的细胞质线粒体 DNA 可以增强报告细胞中的 TLR9 激活，并且 TLR9 抑制剂可以抑制巨噬细胞中炎症细胞因子的诱导。
电子烟增加循环血液中受损线粒体 DNA 的水平，并诱导 TLR9 的表达，从而增加单核细胞/巨噬细胞中促炎细胞因子的表达，进而导致动脉粥样硬化。我们的结果提出了一种可能性，即 TLR9 激活的干预可能是 ECV 相关炎症和心血管疾病的潜在药物靶点。
