特发性主动脉夹层25例病理学特征及相关因素探讨

Pathological features of idiopathic aortic dissection and its related pathogenetic factors

目的初步探讨特发性主动脉夹层的病理变化和发病机制。方法收集特发性主动脉夹层病例(除外遗传性结缔组织病、高血压、炎症反应、主动脉瓣二叶化畸形)25例,在常规组织形态学观察的基础上,运用弹力纤维和Masson三色染色法及免疫组化结合图像分析,检测动脉中膜弹力纤维、胶原纤维和平滑肌细胞的变化及与弹力纤维合成相关的因子Fibulin-5的变化。结果特发性主动脉夹层的病理变化主要表现于中膜层,为中膜弹力纤维灶性破坏,黏液样基质增多。弹力纤维含量明显低于对照组(P<0.01);胶原纤维含量高于对照组(P<0.05);平滑肌细胞量较对照组明显少(P<0.05);Fibulin-5阳性细胞的阳性表面积率显著低于正常对照组(P<0.05)。Fibulin-5含量与弹力纤维含量呈正相关(P<0.05)。结论特发性主动脉夹层的病理变化主要是中膜层变化。Fibulin-5蛋白减少引起的弹力纤维合成减少是导致特发性主动脉夹层的发病因素之一,Fibulin-5蛋白对检测特发性主动脉夹层具有诊断意义。

Objective To explore the pathologic feature and pathogenesis of the idiopathic aortic dissection. Methods Twenty-five cases of idiopathic aortic dissection（ except hereditary connective tissue disease,hypertension,inflammation and bicuspid aortic valve） were selected in Fuwai Hospital from the October 2010 to October 2012. To analyze the amounts of elastic fibres and expression of fibulin-5 within the aortic wall,Weigert-Van Gieson staining,Masson staining and immunohistochemistry were performed. Results It was observed that elastic fibers were damaged focally and myxoid matrix increased in aortic media in idiopathic aortic dissection. The contents of elastic fibers were decreased in idiopathic aortic dissection compared with control group（ 18. 2± 8% vs 43. 6 ±2. 5%,P〈0. 001）. The levels of collagen were increased compared with control group（ 24. 3 ±3. 4% vs 18. 0 ±3. 8%,P〈0. 05）. The number of smooth muscle cell was larger than that of control group（ 15. 8 ±3. 9% vs 33. 4 ±10. 6%,p 0. 05）. The expression of fibulin-5 was also decreased in the aortic dissection patients,compared with control group（ 2. 4 ±1. 7% vs 6. 9 ±2. 5%,P〈0. 05）. The relation between fibulin-5 levels and the level of elastic fibers were positive. Conclusion Patients with idiopathic aortic dissection exhibit significantly decreased expression of fibulin-5 in aortic media. Decreased fibulin-5 may contribute to the pathogenesis of aortic dissection by impairing the assembly of elastic fibers.