Modulation of matrix metalloproteinase and TIMP-1 expression by TGF-β₁ in cultured human RPE cells

Abstract

In order to investigate the effects of TGF-β₁ on the expression of MMP-2, −9 and TIMP-1 in human retinal pigment epithelial (RPE) cells, the third-sixth passage cultured RPE cells were treated with TGF-β₁ at different concentrations (0. 01, 0. 1, 1. 0, 10 ng/mL), the expression of MMP-2, −9 and TIMP-1 mRNA was detected by semi-quantitative RT-PCR assays. MMP-2, −9 and TIMP-1 mRNA were expressed in the cultured RPE cells. The values of MMP-2/β-actin in the cells treated with 0. 1, 1. 0, 10 ng/mL TGF-β₁ were 1.04±0.04, 1.07±0.02 and 1.11±0.03, respectively, significantly higher than in the control group (0.96±0.03,P<0.05–0.01). The expression of MMP-2 mRNA could be up-regulated by TGF-β₁, in a dose-dependent manner. The expression of MMP-9 mRNA in the cultured RPE cells was slightly up-regulated by various TGF-β₁ concentrations treatment. The values of TIMP-1/β-actin in the cells treated with 0.01 and 0.1 ng/ mL TGF-β₁ were 0.85±0.01 and 0.97±0.02 respectively, significantly lower than in the control group (1.07±0.04,P<0.01), indicating that the expression of TIMP-1 mRNA was down-regulated by TGF-β₁ at low concentrations. But along with the increase of TGF-β₁ concentrations (1.0 and 10 ng/mL), the expression of TIMP-1 mRNA was slightly up-regulated, not significantly different from that in the control group (P>0.05). It was concluded that TGF-β₁ might play an important role in the up-regulation of the expression of MMP-2 in RPE cells and result in a directional shift in the balance between MMP and TIMP. This may be facilitated for RPE cells to migrate in the pathogenesis of vitreoretinopathy.

Keywords

matrix metalloproteinase / tissue inhibitor of matrix metalloproteinase / transforming growth factor β₁ / human retinal pigment epithelial cells

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