Abstract
Abstract: :
Purpose: Recent studies report that amyloid ß(Aß) deposition in drusen is related to age–related macular degeneration (AMD). To investigate the molecular mechanisms of secondary development of choroidal neovascularization (CNV), we investigated the gene expression profile of angiogenesis–related factors induced by Aß in human retinal pigment epithelial (RPE) cells. Methods: mRNA expression of genes regulating the metabolism of Aß(Aßprecursor protein, ß–secretase and neprilysin) was analyzed in human RPE cells by reverse transcription–polymerase chain reaction. At confluency, cells were treated with Ab1–40 for 24 h. The expression of vascular endothelial growth factor (VEGF) and pigment epithelium–derived factor (PEDF) in RPE cells was analyzed using real–time polymerase chain reaction, enzyme linked immunosorbent assay, and Western blotting. The conditioned medium from RPE cells incubated with Aß was also used for in vitro angiogenesis assay. Results: Gene expression of Aß precursor protein, ß–secretase, and neprilysin was detected in RPE cells. Aß treatment induced a marked increase in VEGF at both mRNA and protein levels, but a marked decrease in PEDF protein levels. In the in vitro angiogenesis assay, conditioned medium from human RPE cells treated with Aß peptide induced a dramatic increase in tubular formation. Conclusions: RPE cells regulate Aß deposition through the expression of genes regulating Aß metabolism. Once Aß is pathologically accumulated, however, Aß might modulate the expression of angiogenesis–related factors in RPE cells and has a critical role in the secondary development of CNV from drusen in patients with AMD.
Keywords: age–related macular degeneration • choroid: neovascularization • retinal pigment epithelium