Influence of high level TGF-beta1 on scleral thickness

In order to explore the role of TGF-beta1 in scleral remodeling and the possible mechanism, the influence of high level TGF-beta1 on scleral thickness and the expression of MMP-2 and TIMP-2 was investigated in a TGF-beta1 transgenic mouse model. Alb/TGF-beta1 (Cys(223,225)Ser) TGF-beta1 transgenic mice were used as experimental subjects and non-transgenic littermates as controls. Plasma levels of TGF-beta1 were determined by ELISA. TGF-beta1, MMP-2 and TIMP-2 levels in sclera were detected by using Western blot. The thickness of posterior sclera was measured by computerized image analysis of a midsagittal section. Mean difference was analyzed with independent t-test. The results showed plasma levels of TGF-beta1 in transgenic mice were 1.68 times as much as that in the controls (P<0.01). TGF-beta1 levels in the sclera of transgenic mice were 2.68 times of the controls (P<0.01). Posterior scleral thickness in transgenic mice were significantly thicker than in the controls. There was no significant difference in the MMP-2 levels between transgenic mice and controls, but the TIMP-2 levels were increased significantly in transgenic mice as compared with those in the controls. It was suggested that high levels of TGF-beta1 in transgenic mice could result in the increased scleral thickness by inducing the expression of TIMP-2 to suppress the activity of MMP-2, finally inhibiting the degradation of collagen.