Chen Y L, Chang Y J, Jiang M J
Institute of Anatomy, National Yang-Ming University, Shih-Pai, Taipei, Taiwan, ROC.
Atherosclerosis. 1999 Mar;143(1):115-23. doi: 10.1016/s0021-9150(98)00285-8.
Monocyte adherence to the endothelium and subsequent migration into the subendothelial space are important early events in atherogenesis. Monocyte chemotactic protein-1 (MCP-1) has been shown to be highly expressed in both human atheroma and advanced atherosclerotic lesions of experimental animals. To establish the temporal correlation between MCP-1 expression and plaque development, we examined the expression of MCP-1 during atherogenesis of hypercholesterolemic rabbits using Northern blot analysis, in situ hybridization, and immunohistochemistry. New Zealand White rabbits were fed with 2% cholesterol-containing diet for 1 day, 3 days, 1 week, 3 weeks or 6 weeks. The plasma levels of total cholesterol were significantly increased 3 days after cholesterol feeding and continued to increase during the entire cholesterol-feeding period. Northern blot analysis showed that MCP-1 mRNA levels remained unchanged following cholesterol feeding for up to 1 week, were higher than control levels at 3-week and increased even higher at 6-week. In situ hybridization showed that after 3 weeks of cholesterol feeding, MCP-1 mRNA expression was up-regulated in newly-formed fatty streaks and parts of tunica media in the presence or absence of fatty streaks. At 6-week, pronounced MCP-1 mRNA expression was detected with similar distribution. In contrast, MCP-1 mRNA was detected only in a few endothelial cells and adventitia in control and experimental groups feeding cholesterol up to 1-week. Immunostaining of serial sections indicated that MCP-1 was expressed by macrophages and smooth muscle cells in rabbits fed with cholesterol for 3 or 6 weeks. No MCP-1 was detected in intima or media in all other groups. These results show that a lag period exists between serum cholesterol increase and upregulation of MCP-1 expression, suggesting that cholesterol modifications (e.g. oxidation) are required to stimulate MCP-1 expression. In addition, MCP-1 expressed by both macrophages and smooth muscle cells during the initial stages of atherosclerosis is likely to contribute to the development of fatty streaks in hypercholesterolemic rabbits.
单核细胞黏附于内皮并随后迁移至内皮下间隙是动脉粥样硬化发生过程中的重要早期事件。单核细胞趋化蛋白-1（MCP-1）已被证明在人类动脉粥样硬化斑块和实验动物的晚期动脉粥样硬化病变中均有高表达。为了确定MCP-1表达与斑块形成之间的时间相关性，我们采用Northern印迹分析、原位杂交和免疫组织化学方法，检测了高胆固醇血症兔动脉粥样硬化形成过程中MCP-1的表达情况。将新西兰白兔喂以含2%胆固醇的饲料1天、3天、1周、3周或6周。喂食胆固醇3天后，血浆总胆固醇水平显著升高，并在整个胆固醇喂养期间持续升高。Northern印迹分析显示，喂食胆固醇长达1周后，MCP-1 mRNA水平保持不变，3周时高于对照水平，6周时进一步升高。原位杂交显示，喂食胆固醇3周后，在新形成的脂肪条纹以及有或无脂肪条纹的中膜部分，MCP-1 mRNA表达上调。6周时，检测到明显的MCP-1 mRNA表达，分布相似。相比之下，在喂食胆固醇长达1周的对照组和实验组中，仅在少数内皮细胞和外膜中检测到MCP-1 mRNA。连续切片的免疫染色表明，喂食胆固醇3周或6周的兔子中，巨噬细胞和平滑肌细胞表达MCP-1。在所有其他组的内膜或中膜中均未检测到MCP-1。这些结果表明，血清胆固醇升高与MCP-1表达上调之间存在滞后阶段，提示胆固醇修饰（如氧化）是刺激MCP-1表达所必需的。此外，动脉粥样硬化初始阶段由巨噬细胞和平滑肌细胞表达的MCP-1可能有助于高胆固醇血症兔脂肪条纹的形成。
