Department of Vascular Surgery, Shanghai Huashan Hospital, Fudan University, Shanghai 200040, China.
Department of General Surgery, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, 2800 Gongwei Road, Pudong, Shanghai 201399, China.
Biosci Rep. 2021 May 28;41(6). doi: 10.1042/BSR20204250.
It has been demonstrated that trimethylamine N-oxide (TMAO) serves as a driver of atherosclerosis, suggesting that reduction of TMAO level might be a potent method to prevent the progression of atherosclerosis. Herein, we explored the role of TMAO in the stability of carotid atherosclerotic plaques and disclosed the underlying mechanisms. The unstable carotid artery plaque models were established in C57/BL6 mice. L-carnitine (LCA) and methimazole (MMI) administration were applied to increase and reduce TMAO levels. Hematoxylin and eosin (H&E) staining, Sirius red, Perl's staining, Masson trichrome staining and immunohistochemical staining with CD68 staining were used for histopathology analysis of the carotid artery plaque. M1 and M2 macrophagocyte markers were assessed by RT-PCR to determine the polarization of RAW264.7 cells. MMI administration for 2 weeks significantly decreased the plaque area, increased the thickness of the fibrous cap and reduced the size of the necrotic lipid cores, whereas 5-week of administration of MMI induced intraplate hemorrhage. LCA treatment further deteriorated the carotid atherosclerotic plaque but with no significant difference. In mechanism, we found that TMAO treatment impaired the M2 polarization and efferocytosis of RAW264.7 cells with no obvious effect on the M1 polarization. In conclusion, the present study demonstrated that TMAO reduction enhanced the stability of carotid atherosclerotic plaque through promoting macrophage M2 polarization and efferocytosis.
已有研究表明，氧化三甲胺（TMAO）可促进动脉粥样硬化的发生，提示降低 TMAO 水平可能是预防动脉粥样硬化进展的有效方法。在此，我们探讨了 TMAO 在颈动脉粥样硬化斑块稳定性中的作用，并揭示了其潜在机制。通过在 C57/BL6 小鼠中建立不稳定颈动脉斑块模型，应用左卡尼汀（LCA）和甲巯咪唑（MMI）分别增加和降低 TMAO 水平。通过苏木精和伊红（H&E）染色、天狼猩红染色、Perl’s 染色、Masson 三色染色和 CD68 免疫组化染色进行颈动脉斑块的组织病理学分析。通过 RT-PCR 评估 M1 和 M2 巨噬细胞标志物，以确定 RAW264.7 细胞的极化情况。连续 2 周给予 MMI 可显著减少斑块面积，增加纤维帽厚度，减少坏死脂质核心的大小，而给予 5 周的 MMI 则会诱导斑块内出血。LCA 处理进一步恶化了颈动脉粥样硬化斑块，但无显著差异。在机制方面，我们发现 TMAO 处理会损害 RAW264.7 细胞的 M2 极化和吞噬作用，但对 M1 极化无明显影响。综上，本研究表明，降低 TMAO 水平通过促进巨噬细胞 M2 极化和吞噬作用增强了颈动脉粥样硬化斑块的稳定性。
