肝素对LDL受体基因敲除小鼠基质金属蛋白酶-2表达的抑制及抗动脉粥样硬化作用

Heparin Inhibits the production of matrix metalloproteinase-2 and improves atherosclerosis in LDL receptor-deficient mice

目的旨在明确动物水平肝素对低密度脂蛋白受体（LDLR）基因敲除小鼠动脉粥样硬化及硬化斑块内基质金属蛋白酶-2表达的影响。方法将16只7周龄LDLR基因敲除小鼠随机分成两组，分别接受无菌注射液和肝素皮下注射干预。所有小鼠均给予相同的高脂＋高蛋氨酸饮食，干预治疗12周后处死所有小鼠，分别检测两组小鼠总胆固醇、HDL-C、甘油三酯和同型半胱氨酸；测定其主动脉内膜面及窦部粥样硬化面积；免疫组织化学检测窦部粥样硬化斑块内基质金属蛋白酶-2的表达。结果肝素可明显降低小鼠血清总胆固醇水平，并升高HDL—C水平（均P〈0．01）；而对血中甘油三酯和同型半胱氨酸水平无明显影响（均P〉0.05）；所有小鼠在主动脉内膜面和窦部均有动脉粥样硬化改变，但肝素干预组主动脉内膜面粥样硬化面积较对照组减少40．5％（P〈0.01），主动脉窦部粥样硬化面积与对照组相比也明显减少[（160648±15505）vs（192729±30208）μm^2，P〈0.05）]。与粥样硬化改变相似，肝素干预组主动脉窦部粥样硬化斑块内基质金属蛋白酶-2的表达较对照组减少49．3％（P〈0.01），结论肝素能抑制粥样硬化斑块内基质金属蛋白酶-2的表达，并减轻小鼠动脉粥样硬化病变。抑制基质金属蛋白酶-2的表达可能是肝素抗动脉粥样硬化的机制之一。

Objective To investigate the effects of heparin on atherosclerosis and the production of extracellular matrix metalloproteinase-2 in low-density lipoprotein receptor-deficient {LDLr^-/-）mice. Methods Sixteen 7-week-old LDLr^-/- mice were randomized to receive sterile water or heparin. All mice were fed a high-fat and high-methionine diet. At the age of 19 weeks, the mice were sacrificed. The levels of total cholesterol （TC）, high density lipoprotein cholesterol （HDL-C） and triglyceride （TG） were measured by Abbott AerosetTM fully automatic clinical biochemical analyzer; homocysteine （Hcy） was measured by competitive enzyme-linked immunoassay on autoanalyzer. The area of atherosclerotic lesions was measured by computer assisted image analysis and the percentage of lesion area over total luminal surface area was calculated. The expression of MMP-2 protein was detected by immunohistochemistry on a paraffin-embedded section of aortic sinus specimen. Results At the end of study, all mice exhibited atherosclerotic lesions in the aortic sinus and aortic surface. TC was decreased, while HDL-C was increased in heparin group compared with that in control group （P〈 0.01）. TG was not significantly different between two groups （P〉 0.05）.The percentage of atherosclerotic lesions over the aortic surface in heparin group was 40.5%, which was lower than that in the control group （P〈 0.01）. The mean area of atherosclerotic lesions in the aortic sinus was also less in the; heparin group than that in the control group （160648 ±15505 vs 192729 ±30208 μm^2,P 〈 0.05）. Coincidently, the expression ef matrix metalloproteinase-2 in the atherosclerotic lesions in the heparin group was 49.3%, lower than that in the control group （P〈 0.01）. Conclusion Heparin can inhibit the production of matrix metalloproteinase-2 in the atherosclerotic lesions and improve; the atherosclerotic lesions in LDLr^-/- mice, which may be associated with its inhibitory effect on atherosclerosis.