颈动脉粥样硬化斑块稳定性与连接黏附分子A相关性的实验研究

Investigation the correlation between atherosclerotic plaque stability and junctional adhesion molecule A in ApoE-/- mice

目的探讨鼠颈动脉粥样硬化斑块稳定性与连接黏附分子A（JAM—A）表达之间的关系。方法选取8周龄雄性ApoE-/-鼠26只，其中正常组（A组）6只，结扎高脂组（B组）10只，高脂组（c组）10只。24周后，超声（22MHz）检测各组小鼠斑块形成情况，观察斑块内部回声、大小改变；检测各组小鼠血脂四项浓度；综合斑块处巨噬细胞标记物（CD68）、脂质沉积（油红0染色）、胶原纤维（Masson染色）及平滑肌细胞（α—SMA）数量，利用斑块不稳定指数评价斑块稳定性后进行再分组：易损斑块组（D组）、稳定斑块组（E组）；利用免疫组化方法检测局部JAM—A的表达，分析粥样硬化斑块稳定性与JAM—A表达之间的关系。结果超声检查中A组小鼠颈动脉光滑，无斑块形成，B组和c组小鼠颈动脉管壁明显增厚，回声增强，其中45％的小鼠似有斑块稍强回声，25％的小鼠有明显斑块稍强回声，且B组、C组管壁均明显厚于A组（P〈0．05），B组和C组之间差异无统计学意义（P〉0．05）。血脂检测中A组小鼠血脂四项（总胆固醇、甘油三酯、高密度脂蛋白、低密度脂蛋白）均正常，B组和c组小鼠总胆固醇、甘油三酯和低密度脂蛋白均明显高于A组，差异均有统计学意义（P〈0．05），高密度脂蛋白则明显低于A组，差异有统计学意义（P〈O．05）。各项病理检查中A组小鼠颈动脉管壁结构正常，B组和c组小鼠颈动脉管壁结构均发生病理改变，显示有动脉粥样硬化斑块形成；D组不稳定指数（2．53±0．25）比E组（1．53±0．44）高（P〈0．01）；A组JAM—A几乎不表达，D组和E组JAM—A表达明显增多，且D组比E组多（4．05±0．86）％（P〈0．01）；斑块不稳定指数与斑块JAM—A表达的相关系数为0．719（P〈0．01）。结论高频超声探头可观测小鼠颈动脉斑块的形成；动脉粥样硬化斑块形成时，易损性斑块中JAM—A的表达明显增多，提示JAM—A可能作为一个新的判断斑块稳定性的指标。

Objective To explore the relationship between atheroselerotic plaque stability and junctional adhesion molecule A （JAM-A） in atherosclerotic mice. Methods Twenty-six apolipoprotein E gene knockout（ApoE-/ ） mice were divided into three groups. Group A （six mice） was control group, group B （ten mice） was disposed by ligation and high-fat diet and group C was disposed by high-fat diet with ten mice. The formation process of plaques were observed with high resolution ultrasound（22 MHz）, and plaque markers were detected to evaluate palque stability for secondary grouping （group D was vulnerable plaque group and group E was stable plaque group）. The plaque stability were evaluated by plaque vulnerability index and the expression of JAM-A were analyzed using immunohistochemical staining. The relationship between atherosclerotic plaque stability and JAM-A in atherosclerotic mice were estimated with statistical methods at last. Results There was no plaque in carotid artery of group A. On the contrary, obvious plaques were observed in carotid artery of group B and C. The total serum lipids level in group A was normal. But high-fat diet could obviously decrease the serum HDL-cholesterol level of group B and group C when compared with the controls（ P〈0.05）. High-fat diet could increase the ratio of non- HDL-cholesterol （TC, TG, LDL）. As shown with pathological staining, the content of extracellular lipids and foam cells in the plaque were significantly increased vs. control （P 〈 0.05）. On the contrary, the content of smooth muscle cells and collagen fibers were significantly increased vs. control（ P 〈0.05）. The plaque vulnerability index of group D was higher than that in group E（ P 〈0.01 ）. The expression of JAM- A was increased in group D and E, and in group D was higher（ P 〈0.01）. While, few JAM-A expression in group A. There was significant correlation between plaque vulnerability index and JAM-A （P〈0.01）. Conclusions High resolution ultrasound（22 MHz） can observe the formation of carotid plaque in ApoE-/- mice. There was a positive correlation between JAM-A expression and the vulnerability of plaque in carotid artery. JAM-A might be used for evaluation of plaque stability as a new indicator.