Role of Retinal Pigment Epithelial Cell β-Catenin Signaling in Experimental Proliferative Vitreoretinopathy

Proliferative vitreoretinopathy is caused by the contraction of fibrotic membranes on the epiretinal surface of the neurosensory retina, resulting in a traction retinal detachment and loss of visual acuity. Retinal pigment epithelial (RPE) cells play an important role in formation of such fibrotic, contractile membranes. We investigated the role of Wnt/beta-catenin signaling, a pathway implicated in several fibrotic diseases, in RPE cells in proliferative vitreoretinopathy. In vitro culture of swine RPE sheets resulted in nuclear translocation of beta-catenin in dedifferentiated RPE cells. FH535, a specific inhibitor of beta-catenin signaling, reduced the outgrowth of cultured RPE sheets and prevented dedifferentiated RPE cell proliferation and migration. It also inhibited formation of contractile membranes by dedifferentiated RPE cells on collagen I matrices. Expression and function of the beta-catenin signaling target connexin-43 were down-regulated by FH535, and functional blockade of connexins with carbenoxolone also prevented the in vitro formation of fibrotic, contractile membranes. Intravitreal injection of FH535 in swine also inhibited formation of dense, contractile membranes on the epiretinal surface and prevented development of traction retinal detachment. These findings demonstrate that beta-catenin signaling is involved in formation of contractile membranes by dedifferentiated RPE cells and suggest that adjunctive treatment targeting this pathway could be useful in preventing proliferative vitreoretinopathy.