Immunohistochemical localization of FGF-5 and VEGF in epiretinal membranes

Purpose. Proliferative vitreoretinopathy (PVR) and proliferative diabetic retinopathy (PDR) remain the two most common intraocular proliferative diseases with devastating outcome. Growth factors are thought to play an important role in the pathogenesis of these diseases. Apart the better known Fibroblast Growth Factor-1 and -2 (FGF-1 and -2), little is known about FGF-5. Vascular Endothelial Growth Factor (VEGF) is known to be primarily involved in vascular proliferative diseases, whereas little is known in terms of avascular diseases. In order to determine their role in the mentioned diseases we performed immunohistochemical stainings of epiretinal membranes. Methods. Human surgical specimens of epiretinal membranes were obtained trom 11 eyes with PDR and 3 eyes with PVR, fixed in 4% buffered paraformaldehyde and embedded in immunobed. Sections were immunostained with an affinity-purified antibody against an internal sequence of FGF-5 and with a commercially available affinity-purified antibody corresponding to the first 20 residues of human VEGF. Slides were visualized using the ABC-System (Avidin-Biotin-Peroxidase Complex) Control studies were performed with non-immune IgG and preabsorbed VEGF antibody respectively. Results. The results of these studies indicate that immunoreactive FGF-5 is present in most cells of vascular (including endothelial cells) and avascular membranes, but is absent in extracellular matrix. A similar staining pattern could be observed for VEGF. Conclusions. These two proteins are remarkably co-expressed in both vascular and avascular epiretinal membranes arising from PDR and PVR, respectively. This result questions the idea that the presence of a single angiogenic factor determines the vascular status of an epiretinal proliferation.