The expression of advanced glycation endproduct receptors in rpe cells associated with basal deposits in human maculas

Abstract

Basal deposits within Bruch's membrane are associated with aging and age-related macular degeneration (AMD) although the factors causing their formation are incompletely understood. Advanced glycation endproducts (AGEs) accumulate in Bruch's membrane including basal deposits and drusen with aging. One mechanism by which AGEs alter a cell's phenotype is via AGE receptors. The purpose of this study was to immunolocalize and quantify the expression of AGE receptors by RPE cells associated with basal deposits or normal Bruch's membrane that were microdissected from human maculas. Postmortem eyes from 14 aged control donors and five donors with non-neovascular AMD were cryopreserved. RPE cells associated with normal Bruch's membrane or basal deposits were laser capture microdissected. The RNA was extracted and used for RT-qPCR to quantify the expression of RAGE, AGE R1, AGE R2, and AGE R3. Streptavidin alkaline phosphatase immunohistochemistry for these receptors was also performed and sections were bleached from 14 normal and nine AMD donors. RT-qPCR showed significant upregulation of RAGE, AGE R1, and AGE R3 in RPE cells overlying basal deposits compared to cells attached to morphologically normal Bruch's membrane. Immunohistochemical analysis for RAGE, AGER1, R2, and R3 showed diffuse, light staining of RPE cells and strong choriocapillaris staining in areas of normal Bruch's membrane. In areas of basal deposits, the RPE had more intense staining for RAGE and AGER1 compared to regions of normal Bruch's membrane. These results suggest that AGE receptors could influence the formation of basal deposits during aging and AMD.

Vascular endothelial growth factor in eye disease

“…RAGE are upregulated in basal deposits from human AMD eyes compared to normal samples (Yamada et al, 2006). AGE have been reported to induce CEC proliferation, VEGF expression and MMP-2 expression in vitro (Hoffmann et al, 2002) and to increase expression of VEGF mRNA from RPE (McFarlane et al, 2005).…”

“…Drusen are subretinal deposits within the RPE basement membrane and Bruch's membrane, and have been shown, as discussed earlier, to be composed of a number of compounds [complement or inflammatory components (Hageman et al, 2001;Crabb et al, 2002), cholesterol and apolipoproteins (Li et al, 2006a), and oxidative modification of lipoproteins, ECM components, TIMP-3, serum albumin, glycoproteins, and crystallins (Nakata et al, 2005;Hollyfield et al, 2003;Yamada et al, 2006)], some of which cause or are associated with an overexpression of VEGF.…”

Intraocular expression and release of high-mobility group box 1 protein in retinal detachment

“…2,4 In particular, RAGE has been thought to be a crucial receptor for HMGB1-induced cell migration through ERK activation. 33 The expression of RAGE at the RNA and protein level was identified in human RPE 35 and ARPE-19 cells 36,37 in previous studies. It was also shown that the expression of RAGE and HMGB1 was colocalized in the proliferative membrane from an eye with proliferative retinal disease.…”

Recent Advances in Ocular Drug Delivery Systems

“…These changes cause increased calcification of elastic fibers [42], increased cross-linkage of collagen fibers [41] and increased turnover of glycosaminoglycans [43,44]. In addition, advanced glycation end products and lipofuscin accumulate in BM [45][46][47]. Thickness changes of choroid and BM might affect drug permeability from subconjunctiva or episcleral space into the retina and the vitreous.…”