Transforming growth factor-beta1 induces alpha-smooth muscle actin expression and fibronectin synthesis in cultured human retinal pigment epithelial cells

Background : Proliferative vitreoretinopathy is a serious complication of retinal detachment, yet its pathogenesis is not fully understood. Retinal pigment epithelial cells and glial cells are found in the fibrous membranes in proliferative vitreoretinopathy. Many cytokines are involved in the pathology. Transforming growth factor (TGF)‐β₁, a cytokine found in serum, has been shown to be an important factor regulating the synthesis of fibrous extracellular matrix in proliferative vitreoretinopathy. Methods : Cultured human retinal pigment epithelial cells were used in the experiments. The effects of TGF‐β₁ on phenotype and function in retinal pigment epithelial cells were recorded as changes in the expression of α‐smooth muscle actin and fibronectin synthesis using immunohistochemistry and enzyme‐linked immunosorbent assay, respectively. Results : TGF‐β₁ induced the expression of α‐smooth muscle actin (P < 0.0001, n = 3), and significantly increased the synthesis of fibronectin by cultured human retinal pigment epithelial cells (P < 0.01, n = 4). Conclusions : Elevated levels of TGF‐β₁ in proliferative vitreoretinopathy may contribute to phenotype changes in retinal pigment epithelial cells leading to matrix deposition and contraction. Since the elevated levels of TGF‐β₁ may emanate from a number of diverse sources in proliferative vitreoretinopathy, developing an antagonist to TGF‐β₁ may offer an approach to the treatment of proliferative vitreoretinopathy.