二肽基肽酶-4抑制内皮修复的病理机制：SDF-1α/CXCR4—Ephrin-B2

Delate endothelialization is the main reason which will lead to the formation of thrombosis after percutaneous coronary interventions. Ourprevious research conform that inhibit the expression DPP-4 which belong to the serine protease family has the ability to reverse the process of intimal hyperplasia. Decrease the activity of DPP-4 can stimulate the expression of SDF-1α, and then mobilize the endothelial progentior cell. Therefore we hypothesize that increase the activity of DPP-4 is closely related to change the balance between Ephrin-B2 and SDF-1α/CXCR4 to regulate the expression of transcription factor in respond to the synthesis of dense peripheral band and F-actin in endothelial cell, prohibit the migration of endothelial cell. We will use balloon injury model, vascular function studies and molecular biology techniques determine the signaling pathway by which increase the activity of DPP-4 play important role in regulate the recovery of EC which lead to the thrombosis formation after PCI. This project will put forward new sight and potential therapeutic target to treatment delate endothelialization after PCI.

内皮细胞修复滞后是经皮冠状动脉介入治疗（PCI）术后支架内血栓形成的主要原因，其确切发生机制尚未阐明。我们前期实验发现丝氨酸蛋白酶家族成员二肽基肽酶-4（DPP-4）活性下调具有抑制血管损伤后血管内膜增生的作用。体内DPP-4活性抑制通过上调SDF-1α表达从而促进内皮祖细胞动员参与血管损伤后修复。因此本课题假设：血管机械性损伤后，体内DPP-4活性升高诱导Ephrin-B2与SDF-1α/CXCR4竞争性激活下游转录因子，促细胞致密外周束生成而抑制细胞纤维型肌动蛋白生成，迟滞内皮细胞迁移修复。为证实这一假说，我们将复制SD鼠颈动脉球囊损伤模型，通过血管功能学实验和分子生物学等技术，从整体-组织-细胞三个水平，证明DPP-4活性升高是PCI术后由支架内内皮修复障碍导致血栓形成的主要原因。本课题将从新的视角阐明PCI术后内皮修复滞后的分子机制，并为其防治提供新靶点。

内皮细胞修复滞后是经皮冠状动脉介入治疗（PCI）术后支架内血栓形成的主要原因。本项目研究结果显示血管机械性损伤后，血管内皮细胞修复滞后，出现血管内膜增生和炎症因子生成，给予DPP-4抑制剂Anagliptin后,抑制由血管机械性损伤所引起的血管内膜增生及炎症因子（SDF-1α、IL-6, IL-1β and TNF-α）生成。除此之外，血管损伤后，抗氧化蛋白SOD-1表达下降，而Ephrin-B2表达升高，给予Anagliptin逆转由损伤引起的SOD-1表达下降及Ephrin-B2表达升高。凋亡实验证实，应用H2O2处理HUVECs后细胞出现明显凋亡，NOX-4及凋亡相关蛋白caspase-3、Bcl-2、Bax和cyto C表达明显改变，给予Anagliptin后抑制由H2O2引起的细胞凋亡及凋亡相关蛋白的异常表达。迁移实验证实，应用H2O2处理HUVECs后，细胞内ROS生成增加，SOD-1表达抑制并伴有明显细胞迁移抑制，免疫组化证实细胞迁移下降与细胞内骨架蛋白F-actin生成下降有关。给予Anagliptin后拮抗由细胞内氧化应激异常所导致的F-actin生成改变，进而促进损伤后细胞迁移修复。进一步研究证实，Anagliptin通过JNK/RhoA途径调控F-actin生成。结论:1）Anagliptin通过调控DPP-4活性，抑制损伤血管内膜增生及血浆炎症因子表达；2）Anagliptin促损伤后血管内皮修复；3）Anagliptin拮抗由H2O2引起的细胞凋亡；4）Anagliptin通过JNK/RhoA途径调控细胞骨架F-actin生成，最终促细胞损伤后迁移。该项目为PCI术后内皮修复滞后提供新的治疗思路及治疗靶点。