大鼠角膜化学伤后PEDF和VEGF的不平衡表达

Unbalanced expression of PEDF and VEGF in experimental corneal neovascularization

目的比较硝酸银化学伤后大鼠角膜和正常角膜色素上皮衍生因子(PEDF)和血管内皮生长因子(VEGF)表达水平,揭示两者与角膜新生血管的相关性。方法10只大鼠左眼角膜硝酸银化学伤后为实验组,右眼为正常对照组,伤后15d行免疫组织化学法定位及Westernblot定量检测样本角膜PEDF、VEGF等的表达。结果免疫组织化学检查实验组角膜VEGF、碱性成纤维细胞生长因子(bFGF)强表达,PEDF未见表达或弱表达。正常组角膜PEDF高表达,VEGF弱表达,bFGF几乎不表达。WesternBlot分析实验组角膜PEDF表达明显下降(t=8.0049,P<0.01),VEGF表达显著升高(t=48.3637,P<0.01)。结论角膜严重化学伤后新生血管抑制因子PEDF破坏,刺激因子VEGF产生增加,PEDF/VEGF比值降低,角膜血管新生。

Objective The current research showed that vascular endothelial growth factor （VEGF）, a stimulating factor of neovascularization, and pigment epithelium-derived factor（ PEDF）, a inhibitory factor of neovascularization, keep a relative balance level in normal tissue,and the unbalance expression of PEDF and VEGF plays a critical role in the formation of new blood vessel in human organs. This study was to compare the expression levels of PEDF and VEGF in normal rat cornea and experimental corneal neovascularization and explored the effect of PEDF on corneal neovascularization. Methods Corneal neovascularization was induced in the left eyes of 10 healthy SD rats by silver nitrate chemical bum and the right eyes served as control. PEDF and VEGF were measured 15 days after chemical bum by Western blot analysis,and the cellular localization were determined by immunohistochemistry. Results The new blood vessels formed in cornea at 15 days following chemical bum. Intensive PEDF immunostaining was detected in normal corneal samples of rat with a brown staining mainly in the epithelium and endothelium of the cornea but only faint staining in chemical burned rat cornea. Cauterized corneal samples showed a intensive expression of VEGF and bFGF with brown color mainly in the epithelium and blood vessels. Western blot analysis determined that the average PEDF level in chemical burn corneal samples of rat was dramatically lower than those in normal comea（t = 8.00,P 〈 0. 01 ）and that of VEGF in cauterized corneal samples of rat was significantly higher than in the normal cornea （t = 48. 36,P 〈 0. 001 ）. Conclusion The rat cornea chemical burned by silver nitrate exhibits significantly lower PEDF expression and higher VEGF expression. The decreased PEDF levels in cauterized cornea may play an important role in the formation and progression of corneal neovascularization.