骨保护素在腹主动脉瘤中的表达及作用

目的：探讨骨保护素（OPG）的表达在腹主动脉瘤（AAA）形成中的作用。方法：收集20例AAA组织和6例正常腹主动脉组织，用补片法构建兔AAA动物模型（18只AAA模型动物分别于造模后7，21，35 d取材，以6只假手术兔为对照）。用免疫组化法检测OPG在人AAA组织与正常腹主动脉组织中的表达；Western blot和RT-PCR法检测上述组织以及动物模型AAA组织中OPG、基质金属蛋白酶9（MMP-9）蛋白及mRNA的表达；末端转移酶标记（TUNEL）法观察动物模型AAA组织中膜血管平滑肌细胞（VSMC）的凋亡情况。结果：免疫组化显示，人AAA组织中OPG蛋白表达量较正常腹主动脉组织增加，且随AAA直径的增大而增加，在破裂性AAA组织中表达量最高。Western blot和RT-PCR结果显示，OPG与MMP-9蛋白及mRNA的表达在人AAA组织及动物模型AAA组织组均较各自的对照组明显升高（P<0.05），且两者的蛋白与mRNA表达水平均随瘤体直径的增加或造模时间的延长而逐渐增加。TUNEL染色显示模型组VSMC凋亡细胞较对照组明显增加，且随造模时间延长有增加趋势（P<0.05）。结论：OPG表达水平与AAA的发生发展密切相关，机制可能与其促进MMP的表达和诱导VSMC凋亡有关。

Osteoprotegerin expression in abdominal aortic aneurysm tissue and its impact

Objective: To investigate the role of osteoprotegerin (OPG) expression in occurrence and development of the abdominal aortic aneurysm (AAA). Methods: Twenty AAA tissue and 6 normal human abdominal aortic tissue samples were collected, and animal AAA model was created in rabbits using a patch technique (18 AAA rabbits were sacrificed to obtain tissue sample at 7, 21 and 35 d after model creation, respectively, with 6 rabbits undergoing sham operation as control). The OPG protein expressions in human AAA and normal human abdominal aortic tissues were detected by immunohistochemical staining, the protein and mRNA expressions of OPG and matrix metalloproteinase 9 (MMP-9) in the above human tissues and AAA tissues from animal models were measured by Western blot and RT-PCR method respectively, and the apoptosis of the vascular smooth muscle cells (VSMCs) in the tunica media of the AAA tissues from animal models was also determined by terminal transferase dUTP nick end labeling (TUNEL) assay. Results: The results of immunohistochemistry showed that OPG expression in human AAA tissue was increased compared with healthy abdominal aortic tissue, which became more evident with the increasing diameter of the aneurysm and was most evident in the ruptured AAA. Results of Western blot and RT-PCR demonstrated that the protein and mRNA expressions of both OPG and MMP-9 in the tissues from either the AAA biopsies or animal models were significantly higher than those in their controls (P<0.05), and the increases were progressive with the increasing diameter of the aneurysm and time duration after model creation. TUNEL assay showed that the apoptosis of VSMCs in model group was significantly increased versus control group with a growing trend towards prolonged period of model creation. Conclusion: OPG expression level is closely connected to the occurrence and development of AAA, and the mechanism may be associated with its stimulating MMP-9 activity and inducing apoptosis of VSMCs.