Inhibitory effect on subretinal fibrosis by anti-placental growth factor treatment in a laser-induced choroidal neovascularization model in mice

AIM: To investigate whether anti-placental growth factor (PGF) can inhibit subretinal fibrosis and whether this effect is mediated by the inhibitory effect of PGF on epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells.METHODS: Subretinal fibrosis model was established in laser induced choroidal neovascularization (CNV) mice on day 21 after laser photocoagulation. Immunofluorescence staining (IFS) of cryosections and enzyme-linked immunosorbent assay (ELISA) were used to detect the expression of PGF. IFS of whole choroidal flat-mounts was used to detect the degree of subretinal fibrosis. IFS of cryosections and ELISA were used to detect the expression of EMT related indicators in subretinal fibrosis lesions.RESULTS: The expression of PGF protein in subretinal fibrosis lesions was significantly up-regulated (P<0.05), and mainly co-stained with pan-cytokeratin labeled RPE cells. Intravitreal injection of anti-PGF neutralizing antibody reduced the area of subretinal fibrosis and the ratio of fibrotic/angiogenic area significantly at the concentrations of 0.25, 0.5, 1.0, and 2.0 μg/μL (all P<0.05). The expression of E-cadherin in the local RPE cells decreased, while α-SMA increased significantly in subretinal fibrosis lesions, and the application of anti-PGF neutralizing antibody could reverse these changes (P<0.05).CONCLUSION: The expression of PGF is up-regulated in the lesion site of subretinal fibrosis and mainly expressed in RPE cells. Intravitreal injection of anti-PGF neutralizing antibody can significantly inhibit the degree of subretinal fibrosis in CNV mice, and this effect may be mediated by the inhibition of PGF on EMT of RPE cells.