Wnt/β-catenin/VEGF通路在副猪嗜血杆菌引起猪内皮细胞损伤中的作用

Role of Wnt/β-catenin/VEGF pathway in endothelial cell damage caused by Haemophilus parasuis in pigs

为探究副猪嗜血杆菌(Haemophilus parasuis,HPS)引起猪渗出性炎症的过程中血管内皮屏障的变化情况,以HPS感染原代猪血管内皮细胞,通过Western blot和荧光定量PCR检测HPS对Wnt/β-catenin通路及其下游靶基因表达的影响,并通过间接免疫荧光和跨内皮电阻测定检测细胞间黏附连接结构的改变。结果显示:HPS感染激活猪内皮细胞中的Wnt/β-catenin信号通路,促使胞质中的β-catenin蛋白发生核转位,导致胞膜处由β-catenin和血管内皮钙黏蛋白(VE-cadherin)构成的黏附连接结构被破坏,细胞通透性增加。抑制Wnt/β-catenin通路下游血管内皮生长因子(VEGF)基因的表达,可以明显抑制β-catenin的核转位,显著恢复内皮细胞间β-catenin和VE-cadherin构成的黏附连接结构,恢复内皮细胞通透性。以上研究结果表明,HPS通过激活猪内皮细胞中Wnt/β-catenin通路,破坏细胞间黏附连接,增加内皮细胞通透性;同时,Wnt/β-catenin通路下游VEGF基因通过正反馈调节效应放大了HPS感染引起的Wnt/β-catenin信号通路的激活效应和细胞结构的损伤。

To investigate the changes of vascular endothelial barrier during exudative inflammation caused by Haemophilus parasuis(HPS)in pigs,primary pig vascular endothelial cells were infected with HPS.The effects on the expression of the Wnt/β-catenin pathway and its downstream target genes were de⁃tected by Western blot and fluorescence quantitative PCR,and the alterations in the structure of intercellu⁃lar adhesion junctions were detected by indirect immunofluorescence and transendothelial electrical resis⁃tance assay.The results showed that HPS infection activated Wnt/β-catenin pathway in porcine endothelial cells,and induced nuclear translocation ofβ-catenin protein in the cytoplasm,resulting in the destruction of the adhesive junction structure composed ofβ-catenin and VE-cadherin at the cell membrane and the in⁃crease of cell permeability.Moreover,inhibition of the expression of VEGF gene downstream of Wnt/β-catenin pathway significantly suppressed the nuclear translocation ofβ-catenin and markedly restored the in⁃tercellular adherens junctions composed ofβ-catenin and VE-cadherin,which benefits the recovery of endo⁃thelial cell permeability.These results suggested that HPS infection disrupted intercellular adherens junc⁃tions and increased endothelial cell permeability by activating the Wnt/β-catenin pathway in porcine endo⁃thelial cells;meanwhile,the VEGF gene downstream of the Wnt/β-catenin pathway amplifies the Wnt/β-catenin pathway activity and cell damage induced by HPS infection through a positive feedback.