静脉指纹分子EphB4在移植静脉适应动脉血流环境中的调控机制

Mechanism of venous molecular fingerprint EphB4 in regulating vein graft adaptation to the arterial hemodynamic environment

摘要:

目的：探讨EphB4在移植静脉适应动脉血流过程中的调控作用及机制。
方法：静脉移植重建动脉模型采用将供体大鼠上腔静脉端端吻合移植到受体大鼠腹主动脉的方式构建，实验分为单纯模型组（供体、受体均为野生型大鼠）、EphB4增强组（供体、受体均为野生型大鼠，移植静脉外膜以EphB4的配体ephrinB2持续刺激）、EphB4减弱组（供体EphB4+/-型转基因大鼠，受体为野生型大鼠），各组分别在建模后1、4周取移植静脉行组织病理学检测；分离并培养野生型及EphB4+/-型大鼠静脉内皮细胞，比较两种细胞在相同浓度ephrinB2刺激下，EphB4膜受体（EphBR）及下游传导通路ERK1/2的磷酸化程度及细胞迁移能力。
结果：与大鼠正常上腔静脉比较，各实验组移植静脉的内膜+中膜厚度、平滑肌肌动蛋白、胶原纤维含量均明显并逐渐增加（均P<0.05）；建模后1周，以上指标的增加程度在各实验组间差异无统计学意义（均P>0.05），但建模后4周，EphB4增强组以上指标的增加程度均明显低于另两组（均P<0.05）。相同浓度ephrinB2刺激下，EphB4+/-型大鼠静脉内皮细胞的EphBR与ERK1/2磷酸化程度、EphB4 mRNA转录活性、迁移能力均明显低于野生型大鼠内皮细胞（均P<0.05）。
结论：静脉分子指纹EphB4的表达量可能对移植静脉重塑的走向起关键作用，机制可能与其通过ERK1/2途径影响内皮细胞功能有关。

Abstract:

Objective: To investigate the regulatory effect of EphB4 in the process of vein graft adaptation to arterial blood flow and the mechanism.
Methods: The animal model of artery reconstruction with vein graft was established by transplantation of the superior vena cava of a donor rat to the abdominal aorta of a recipient rat with an end-to-end pattern. The experiment was divided into simple model group (wild type rats were used for both donors and recipients), EphB4 enhancing group (wild type rats were used for both donors and recipients, and the adventitia of the vein graft was continuously stimulated by the EphB4 ligand ephrinB2) and EphB4 lessening group (EphB4+/– transgenic rats were used for donors and wild type rat were used for recipients). The vein grafts in each group of rats were removed for histopathological examinations at 1 week and 4 weeks after model creation. The vein endothelial cells were isolated from wild type and EphB4+/– type rats and cultured, and then, the degrees of phosphorylation of the EphB4 membrane receptor (EphBR) and ERK1/2 in the downstream transduction pathway as well as the migration abilities in the two types of cells were compared.
Results: Compared with the normal rat superior vena cava, the intima-media thickness, and the contents of smooth muscle actin and collagen fiber in the vein grafts of each experimental group of rats were significantly and increasingly elevated (all P<0.05). The increasing amplitudes of all above variables showed no significant difference among the experimental groups at 1 week after model creation (P>0.05), but were significantly less in EphB4 enhancing group than those in the other two groups at 4 weeks after model creation (all P<0.05). Under the stimulation of same concentration of ephrinB2, the degrees of phosphorylation of EphBR and ERK1/2, transcriptional activity of EphB4 mRNA and migration ability in vein the endothelial cells from the EphB4+/–type rats were significantly reduced compared with those from the wild type rats (all P<0.05).
Conclusion: The expression level of the molecular fingerprint EphB4 may play a key role in the remodeling pattern of the vein grafts, and the mechanism is probably associated with its influencing the function of the endothelial cells via ERK1/2 pathway.