Purpose:
Proliferative diabetic retinopathy (PDR) is associated with increased pro-angiogenic vascular endothelial growth factor (VEGF) and macular edema. VEGF promotes the increased neovascularisation observed in PDR, breakdown of the blood-retinal barrier (BRB) and degradation of the tight-junctions formed between retinal pigment epithelial (RPE) cells by downregulating the tight junctional protein ZO-1, which may also facilitate fluid movement into the retina1. This study aimed to determine the effects of the pro-angiogenic and anti-angiogenic isoforms of VEGF, VEGF165 and VEGF165b respectively, on tight-junctional integrity in retinal pigment epithelial cells.
Methods:
Primary RPEs received one of four treatments: untreated, VEGF165 treated (2.5nM), VEGF165b treated (2.5nM) and treated with both (2.5nM each). 24 hours following treatment, changes in ZO1 expression were observed using immunofluorescence
Results:
Results RPEs treated with VEGF165, showed a significantly decreased (p<0.05) ZO1 staining intensity by 51.1% (±11%, n=9, figure 1a) relative to untreated cells, (figure 1b). VEGF165b treated cells showed no change in ZO1 staining intensity (88.7±17.9%) compared to VEGF165 treated. Cells treated with both isoforms showed no change in ZO1 staining intensity of (84.3±4.5%) when compared to untreated cells.
Conclusions:
The VEGF mediated decrease in ZO1 expression in RPEs, is limited to the pro-angiogenic VEGF165 isoform and blocked by the anti-angiogenic VEGF165b isoform.1. R. Ghassemifar, C. M. Lai, P. E. Rakoczy (2006) VEGF differentially regulates transcription and translation of ZO-1alpha+ and ZO-1alpha- and mediates trans-epithelial resistance in cultured endothelial and epithelial cells Cell Tissue Res 323:117-25
Keywords: diabetic retinopathy • retinal pigment epithelium • vascular endothelial growth factor