The relationship between anti-vascular endothelial growth factor and fibrosis in proliferative retinopathy: clinical and laboratory evidence

Purpose To investigate the progression of epiretinal membranes after intravitreal bevacizumab (IVB) injection therapy in patients with proliferative membranes and evaluate the changes in fibrosis-related cytokines in retinal pigment epithelial cells and glial cells after treatment with bevacizumab. Methods Retrospective study of the proliferative membranes in patients with and without IVB therapy. In vitro, the human adult retinal pigment epithelial (ARPE-19) cells and BV2 microglial cell lines were incubated in different bevacizumab concentrations under hypoxic conditions. Cell culture supernatants and cell lysates were harvested after incubation for 24, 48 or 72hours for ELISA and western blot. Results Bevacizumab accelerated fibrosis in patients with proliferative membranes. Immunofluorescence analysis revealed more intense transforming growth factor 2 (TGF2) and connective tissue growth factor (CTGF) staining in IVB-treated proliferative diabetic retinopathy (PDR) membranes compared with membranes of patients not receiving IVB therapy. This result was consistent with real-time PCR results. Bevacizumab incubation significantly upregulated TGF2 and CTGF in ARPE-19 cells and BV2 microglial cells, but ciliary neurotrophic factor (CNTF) expression was upregulated only in BV2 microglial cells. Conclusions Anti-vascular endothelial growth factor treatment likely accelerates fibrosis in PDR patients via upregulation of TGF2, CTGF and CNTF, suggesting the importance of adjunctive therapy for retinal fibrosis.