elastin and Retinal-Neovascularization

Neovascular AMD involves the activation of choroidal endothelial cells to increase their inflammatory and angiogenic behaviors. Elastin derived peptides (EDPs) can elicit some of these phenotypic changes in endothelial cells. This investigation was performed to follow up on those findings by determining a receptor for these peptides in the human eye as well as evaluating the effects of elevated EDPs on choroidal cells in vitro and in vivo.. The expression of elastin receptor genes including GLB1 was analyzed using reverse transcription PCR. Migration of choroidal endothelial cells was quantified in the presence of inhibitors to different EDP binding proteins. C57BL6 mice were injected with EDPs and studied by electroretinography, transmission electron microscopy, and microarray analysis.. An alternatively spliced form of beta-galactosidase (GLB1) is present on human choroidal endothelial cells and acts as a receptor for EDPs. Elevated levels of circulating EDPs do not affect retinal function in the mouse, but do increase the expression and deposition of collagen IV in the RPE/choroid complex.. EDPs may play a role in neovascular AMD by binding to and inducing neovascular phenotypes in choroidal endothelial cells through their receptor, GLB1. These peptides also cause an increased mRNA expression and deposition of collagen IV in the RPE/choroid, which may alter diffusion properties between the retina and choriocapillaris.

Topics: Alternative Splicing; Animals; beta-Galactosidase; Bruch Membrane; Cathepsin A; Cell Line; Cell Migration Assays; Cell Movement; Choroid; Diffusion; Elastin; Electroretinography; Endothelial Cells; Gene Expression Regulation; Humans; Mice; Mice, Inbred C57BL; Microscopy, Electron, Transmission; Neovascularization, Pathologic; Neuraminidase; Peptides; Phenotype; Retina; Retinal Neovascularization; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger

Very-low-density lipoprotein receptor (VLDLR) in knockout mice (vldlr(-/-)) has been reported to induce subretinal neovascularization. Therefore, VLDLR expression in the wild-type mouse retina was investigated and the retinal angiogenic process in vldlr(-/-) mice was characterized.. VLDLR expression in the retina and in purified retinal vascular endothelial cells (RECs) and retinal pigment epithelial (RPE) cells was determined by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. Angiogenic evolution in vldlr(-/-) mice was examined by fundus fluorescein angiography, histology, double-staining of FITC-dextran perfusion and elastin immunohistochemistry, isolectin staining, and confocal fluorescence microscopy.. VLDLR mRNA was detected in the wild-type mouse retina and in purified RECs and RPE cells. The VLDLR protein was localized in the RPE layer, vessels in the ganglion cell layer, and around the outer limiting membrane of the retina. The retinal pathogenic process in vldlr(-/-) mice recapitulates key features of retinal angiomatous proliferation (RAP) in humans, a subtype of neovascular age-related macular degeneration (AMD). These include neovascular growth originating from retinal vessels and progressing to the subretinal space with intraretinal, subretinal, and choroidal angiogenic stages, RPE disruption and Bruch membrane exposure, retinal-choroidal anastomosis, subsequent photoreceptor degeneration, RPE hyperplasia, and subretinal fibrosis at the end stage.. VLDLR is expressed in the wild-type mouse retina, especially in RECs and RPE cells. The vldlr(-/-) mouse exhibits histologic and angiographic characteristics of RAP and is a reproducible animal model facilitating studies of the molecular mechanisms of RAP.

Topics: Animals; Disease Models, Animal; Elastin; Endothelium, Vascular; Female; Fluorescein Angiography; Fluorescent Antibody Technique, Indirect; Gene Expression; Gene Silencing; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Microscopy, Confocal; Pigment Epithelium of Eye; Receptors, LDL; Retina; Retinal Neovascularization; Retinal Vessels; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger

Dysregulation of the extracellular matrix (ECM) plays an important role in the pathogenesis of age-related macular degeneration (AMD). Elastin is a fibrous protein constituent of the ECM, degradation of which may be detected by the presence of serum elastin-derived peptides (S-EDPs) in circulation. This study was undertaken to estimate levels of S-EDPs in patients with AMD compared with age-matched control subjects.. Fifty-six patients with AMD were classified into two groups: early age-related maculopathy (ARM) and neovascular AMD. The control group consisted of 15 age-matched subjects with no AMD. S-EDP levels in the serum of these subjects was estimated by competitive ELISA, using solubilized alpha-elastin from human aorta and polyclonal antibodies to this antigen.. S-EDPs were significantly higher in patients with AMD than in control subjects. In addition, subjects with neovascular AMD had higher levels of S-EDPs than did those with early disease.. The cause of this association between S-EDPs and AMD is unknown, but it suggests that systemic elastin degradation may increase the risk of conversion from early ARM to neovascular AMD. Further studies are needed to confirm whether the serum level of S-EDPs is a useful predictor of conversion from early ARM to neovascular AMD.

Topics: Aged; Aged, 80 and over; Aging; Antibody Specificity; Elastin; Enzyme-Linked Immunosorbent Assay; Female; Humans; Macular Degeneration; Male; Middle Aged; Peptides; Retinal Neovascularization