转化生长因子-β1转基因小鼠巩膜厚度研究

Increased Scleral Thickness in a TGF-β1 Transgenic Mouse Model

目的采用转化生长因子-β1(TGF-β1)转基因小鼠,研究高水平的TGF-β1对巩膜厚度以及基质金属蛋白酶-2(MMP-2)、基质金属蛋白酶抑制剂-2(TIMP-2)水平的影响,以探讨TGF-β在巩膜重塑中的作用及可能的机制。方法应用Alb/TGF-β1(Cys223,225Ser)转基因小鼠模型作为实验对象,同窝出生的C57BL/6J野生型小鼠作为对照组。ELISA法测定血浆TGF-β1浓度。Western blot法测定巩膜组织TGF-β1、MMP-2及TIMP-2浓度,应用Whatman Biometria凝胶分析软件分析Western blot结果。对全眼球经视神经乳头正中石蜡切片进行数码图像分析测定后极部巩膜厚度。结果TGF-β1转基因小鼠血浆TGF-β1浓度约为野生型对照小鼠的1.68倍(P<0.01),转基因小鼠巩膜组织中TGF-β1的表达水平是野生型小鼠的2.68倍(P<0.01),MMP-2的表达水平和野生型小鼠差异无显著性意义,TIMP-2的水平是野生型小鼠的3.15倍(P<0.01),转基因小鼠后极部巩膜厚度较野生型小鼠显著增厚(P<0.01)。结论TGF-β1浓度增高会导致巩膜增厚。TGF-β1通过升高TIMP-2的水平抑制MMP-2的活性,从而抑制胶原的降解导致巩膜增厚。

Objective To investigate the influence of high levels TGF-β1 on scleral thickness and expression of MMP-2 and TIMP-2 in order to explore the role of TGF-β1 in scleral remodeling and the possible mechnism.Methods Alb/TGF-β1（Cys^223,225Ser） TGF-β1 transgenic mice were used,and non-transgenic littermates were used as controls.Plasma levels of TGF-β1 were quantified by ELISA.TGF-β1,MMP-2 and TIMP-2 levels in sclera were measured by using Western blot.Posterior scleral thickness was measured by computerized image analysis of a midsagittal section.Results Plasma levels of TGF-β1 in transgenic mice were 1.68 times as much as that in normal non-transgenic mice（P〈0.01）.TGF-β1 levels in the sclera of transgenic mice were 2.68 times of non-transgenic mice（P〈0.01）.Posterior scleral thickness in transgenic mice were thicker significantly than that of normal mice.There was no significant difference in MMP-2 levels between transgenic mice and non-transgenic mice,while the TIMP-2 levels in transgenic mice were increased significantly as compared with those in non-transgenic mice（P〈0.01）.Conclusion High levels of TGF-β1 in transgenic mice caused the increased scleral thickness by inducing the expression of TIMP-2,and subsequently suppressing the activities of MMP-2,finally inhibiting the degradation of collagen,resulting in the increased scleral thickness.