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Age-related macular degeneration (AMD) is a major leading cause of irreversible visual impairment in the world with limited therapeutic interventions. Histological, biochemical, genetic, and epidemiological studies strongly implicate dysregulated lipid metabolism in the retinal pigmented epithelium (RPE) in AMD pathobiology. However, effective therapies targeting lipid metabolism still need to be identified and developed for this blinding disease. To test lipid metabolism-targeting therapies, preclinical AMD mouse models are needed to establish therapeutic efficacy and the role of lipid metabolism in the development of AMD-like pathology. In this review, we provide a comprehensive overview of current AMD mouse models available to researchers that could be used to provide preclinical evidence supporting therapies targeting lipid metabolism for AMD. Based on previous studies of AMD mouse models, we discuss strategies to modulate lipid metabolism as well as examples of studies evaluating lipid-targeting therapeutics to restore lipid processing in the RPE. The use of AMD mouse models may lead to worthy lipid-targeting candidate therapies for clinical trials to prevent the blindness caused by AMD.

Age-related macular degeneration (AMD) is the most common cause of blindness among the elderly in the developed world. While treatment is effective for the neovascular or “wet” form of AMD, no therapy is successful for the non-neovascular or “dry” form. Here we discuss the current knowledge on dry AMD pathobiology and propose future research directions that would expedite the development of new treatments. In our view, these should emphasize system biology approaches that integrate omic, pharmacological, and clinical data into mathematical models that can predict disease onset and progression, identify biomarkers, establish disease causing mechanisms, and monitor response to therapy., No effective therapies exist for dry age-related macular degeneration. In this perspective, the authors propose that research should emphasize system biology approaches that integrate various ‘omics’ data into mathematical models to establish pathogenic mechanisms on which to design novel treatments, and identify biomarkers that predict disease progression and therapeutic response.

Significance The complement factor H (CFH) Y402H polymorphism (rs1061170) imparts the strongest risk for age-related macular degeneration (AMD), the leading cause of blindness in the elderly. Popular thinking holds that the CFH H402 variant increases complement activation in the eye, predisposing susceptibility to disease. However, clinical trials of complement inhibitors in AMD patients have failed. Here we provide an explanation, showing CFH variant-specific differences in the presentation of AMD-like pathologies. We show that aged mice expressing the human H402, but not Y402 variant, (i) develop AMD-like symptoms and (ii) display differences in their systemic and ocular lipoprotein levels, but not in their complement activation, after diet. These findings support targeting lipoproteins for the treatment of AMD., One of the strongest susceptibility genes for age-related macular degeneration (AMD) is complement factor H (CFH); however, its impact on AMD pathobiology remains unresolved. Here, the effect of the principal AMD-risk–associated CFH variant (Y402H) on the development and progression of age-dependent AMD-like pathologies was determined in vivo. Transgenic mice expressing equal amounts of the full-length normal human CFH Y402 (CFH-Y/0) or the AMD-risk associated CFH H402 (CFH-H/H) variant on a Cfh−/− background were aged to 90 weeks and switched from normal diet (ND) to a high fat, cholesterol-enriched (HFC) diet for 8 weeks. The resulting phenotype was compared with age-matched controls maintained on ND. Remarkably, an AMD-like phenotype consisting of vision loss, increased retinal pigmented epithelium (RPE) stress, and increased basal laminar deposits was detected only in aged CFH-H/H mice following the HFC diet. These changes were not observed in aged CFH-Y/0 mice or in younger (36- to 40-week-old) CFH mice of both genotypes fed either diet. Biochemical analyses of aged CFH mice after HFC diet revealed genotype-dependent changes in plasma and eyecup lipoproteins, but not complement activation, which correlated with the AMD-like phenotype in old CFH-H/H mice. Specifically, apolipoproteins B48 and A1 are elevated in the RPE/choroid of the aged CFH-H/H mice compared with age-matched control CFH-Y/0 fed a HFC diet. Hence, we demonstrate a functional consequence of the Y402H polymorphism in vivo, which promotes AMD-like pathology development and affects lipoprotein levels in aged mice. These findings support targeting lipoproteins as a viable therapeutic strategy for treating AMD.

The P2X7 receptor (P2X7R) is an ATP-gated ion channel that is a key player in oxidative stress under pathological conditions. The P2X7R is expressed in the retinal pigmented epithelium (RPE) and neural retina. Chronic oxidative stress contributes to the pathogenesis of age-related macular degeneration (AMD). Mice lacking Cu, Zn superoxide dismutase (Sod1) developed chronic oxidative stress as well as AMD-like features, but whether the P2X7R plays a causative role in oxidative stress-induced AMD is unknown. Thus, the main purpose of this study was to test if concurrent knockout (KO) of P2X7R could block AMD-like defects seen in Sod1 KO mice. Using multiple approaches, we demonstrate that Sod1 KO causes AMD-like defects, including positive staining for oxidative stress markers, 3-nitrotyrosine and carboxymethyl lysine, thinning of the RPE and retina, thickening of Bruch's membrane, presence of basal laminar and linear deposits, RPE barrier disruption and accumulation of microglia/macrophages. Moreover, we find that Sod1 KO mice accumulate more microparticles (MPs) within RPE/choroid tissues. Concurrent KO of the P2X7R protects against AMD-like defects and MP accumulation in Sod1 KO mice. Together, we show for the first time, that deficiency of P2X7R prevents in vivo oxidative stress-induced accumulation of MPs and AMD-like defects. This work could potentially lead to novel therapies for AMD and other oxidative stress-driven diseases.

The retinal pigmented epithelium (RPE) forms the outer blood-retinal barrier, provides nutrients, recycles visual pigment, and removes spent discs from the photoreceptors, among many other functions. Because of these critical roles in visual homeostasis, the RPE is a principal location of disease-associated changes in age-related macular degeneration (AMD), emphasizing its importance for study in both visual health and disease. Unfortunately, there are no early indicators of AMD or disease progression, a void that could be filled by the development of early AMD biomarkers. Exosomes are lipid bilayer membrane vesicles of nanoscale sizes that are released in a controlled fashion by cells and carry out a number of extra- and intercellular activities. In the RPE they are released from both the apical and basal sides, and each source has a unique signature/content. Exosomes released from the basolateral side of RPE cells enter the systemic circulation via the choroid and thus represent a potential source of retinal disease biomarkers in blood. Here we discuss the potential of targeted immunocapture of eye-derived exosomes and other small extracellular vesicles from blood for eye disease biomarker discovery.

Age-Related Macular Degeneration (AMD) is a complex multifactorial disease characterized in its early stages by lipoprotein accumulations in Bruch's Membrane (BrM), seen on fundoscopic exam as drusen, and in its late forms by neovascularization (“wet”) or geographic atrophy of the Retinal Pigmented Epithelial (RPE) cell layer (“dry”). Genetic studies have strongly supported a relationship between the alternative complement cascade, in particular the common H402 variant in Complement Factor H (CFH) and development of AMD. However, the functional significance of the CFH Y402H polymorphism remains elusive. In this article, we critically review the literature surrounding the functional significance of this polymorphism. Furthermore, based on our group's studies we propose a model in which CFH H402 affects CFH binding to heparan sulfate proteoglycans leading to accelerated lipoprotein accumulation in BrM and drusen progression. We also review the literature on the role of other complement components in AMD pathobiologies, including C3a, C5a and the membrane attack complex (MAC), and on transgenic mouse models developed to interrogate in vivo the effects of the CFH Y402H polymorphism.

The P2X7 receptor (P2X7R) is an ATP-gated ion channel that is a key player in oxidative stress under pathological conditions. The P2X7R is expressed in the retinal pigmented epithelium (RPE) and neural retina. Chronic oxidative stress contributes to the pathogenesis of age-related macular degeneration (AMD). Mice lacking Cu, Zn superoxide dismutase (Sod1) developed chronic oxidative stress as well as AMD-like features, but whether the P2X7R plays a causative role in oxidative stress-induced AMD is unknown. Thus, the main purpose of this study was to test if concurrent knockout (KO) of P2X7R could block AMD-like defects seen in Sod1 KO mice. Using multiple approaches, we demonstrate that Sod1 KO causes AMD-like defects, including positive staining for oxidative stress markers, 3-nitrotyrosine and carboxymethyl lysine, thinning of the RPE and retina, thickening of Bruch’s membrane, presence of basal laminar and linear deposits, RPE barrier disruption and accumulation of microglia/macrophages. Moreover, we find that Sod1 KO mice accumulate more microparticles (MPs) within RPE/choroid tissues. Concurrent KO of the P2X7R protects against AMD-like defects and MP accumulation in Sod1 KO mice. Together, we show for the first time, that deficiency of P2X7R prevents in vivo oxidative stress-induced accumulation of MPs and AMD-like defects. This work could potentially lead to novel therapies for AMD and other oxidative stress-driven diseases.

Age-related macular degeneration (AMD) is an ocular neurodegenerative disorder and is the leading cause of legal blindness in Western societies, with a prevalence of up to 8 % over the age of 60, which continues to increase with age. AMD is characterized by the progressive breakdown of the macula (the central region of the retina), resulting in the loss of central vision including visual acuity. While its molecular etiology remains unclear, advances in genetics and genomics have illuminated the genetic architecture of the disease and have generated attractive pathomechanistic hypotheses. Here, we review the genetic architecture of AMD, considering the contribution of both common and rare alleles to susceptibility, and we explore the possible mechanistic links between photoreceptor degeneration and the alternative complement pathway, a cascade that has emerged as the most potent genetic driver of this disorder.

An imbalance between activation and inhibition of the complement system has been implicated in the etiologies of numerous common diseases. Allotypic variants of a key complement fluid-phase regulatory protein, complement factor H (CFH), are strongly associated with age-related macular degeneration (AMD), a leading cause of worldwide visual dysfunction, although its specific role in AMD pathogenesis is still not clear. CFH was isolated from individuals carrying combinations of two of the nonsynonymous coding variants most strongly associated with AMD risk, V62/H402 (risk haplotype variants), I62/Y402 (nonrisk haplotype variants), and V62/Y402. These proteins were used in two functional assays (cell surface- and fluid-phase–based) measuring cofactor activity of CFH in the factor I-mediated cleavage of C3b. Although no variant-specific differences in the cofactor activity were detected, when heparan sulfate (HS) was added to these assays, it accelerated the rate of C3b cleavage, and this effect could be modulated by degree of HS sulfation. Bruch’s membrane/choroid, a site of tissue damage in AMD, contains high concentrations of glycosaminoglycans, including HS. Addition of human Bruch’s membrane/choroid to the fluid-phase assay accelerated the C3b cleavage, and this effect was lost posttreatment of the tissue with heparinase III. Binding of CFH variants to Bruch’s membrane/choroid isolated from elderly, non-AMD donor eyes, was similar, as was the functional activity of bound CFH. These findings refine our understanding of interactions of HS and complement and support the hypothesis that these interactions play a role in the transition between normal aging and AMD in Bruch’s membrane/choroid.

Purpose A large body of evidence supports a central role for complement activation in the pathobiology of age-related macular degeneration (AMD), including plasma complement component 5a (C5a). Interestingly, C5a is a chemotactic agent for monocytes, a cell type also shown to contribute to AMD. However, the role monocytes play in the pathogenesis of "dry" AMD and the pharmacologic potential of targeting C5a to regulate these cells are unclear. We addressed these questions via C5a blockade in a unique model of early/intermediate dry AMD and large panel flow cytometry to immunophenotype monocytic involvement. Methods Heterozygous complement factor H (Cfh+/-) mice aged to 90 weeks were fed a high-fat, cholesterol-enriched diet (Cfh+/-∼HFC) for 8 weeks and were given weekly intraperitoneal injections of 30 mg/kg anti-C5a (4C9, Pfizer). Flow cytometry, retinal pigmented epithelium (RPE) flat mounts, and electroretinograms were used to characterize anti-C5a treatment. Results Aged Cfh+/- mice developed RPE damage, sub-RPE basal laminar deposits, and attenuation of visual function and immune cell recruitment to the choroid that was accompanied by expression of inflammatory and extracellular matrix remodeling genes following 8 weeks of HFC diet. Concomitant systemic administration of an anti-C5a antibody successfully inhibited local recruitment of mononuclear phagocytes to the choroid-RPE interface but did not ameliorate these AMD-like pathologies in this mouse model. Conclusions These results show that immunotherapy targeting C5a is not sufficient to block the development of the AMD-like pathologies observed in Cfh+/-∼HFC mice and suggest that other complement components or molecules/mechanisms may be driving "early" and "intermediate" AMD pathologies.

Aging-associated neurodegenerative diseases significantly influence the quality of life of affected individuals. Genetic approaches, combined with genomic technology, have provided powerful insights into common late-onset diseases, such as age-related macular degeneration (AMD). Here, we discuss current findings on the genetics of AMD to highlight areas of rapid progress and new challenges. We also attempt to integrate available genetic and biochemical data with cellular pathways involved in aging to formulate an integrated model of AMD pathogenesis.

To compare spectral domain optical coherence tomography (SDOCT) cross-sectional images of human central retina obtained from donor eyes with and without age-related macular degeneration (AMD) to corresponding histopathology from light micrographs. To establish the utility of SDOCT for localizing pathology in the posterior eyecup, for identifying ocular disease in donor eyes, or for directing subsequent sectioning of retinal lesions for research. Seven consecutive human donor eyes were selected based on age. The eyes, with the anterior segment removed, were imaged by SDOCT with a focusing aspheric lens. Four eyes were from donors with a clinical history of AMD, and three were from age-matched donors with no history of AMD. Histopathological correlation of morphological changes detected in three eyes by SDOCT was obtained for comparison to step serial-sectioned light microscopy images of the formalin-fixed, paraffin-embedded retina. A simplified imaging setup was tested on an enucleated porcine eye for comparison. AMD pathology was detected and localized in four eyes by SDOCT. The SDOCT images correlated with the histopathology observed by light microscopy in each sectioned eye. Pathologies included a subfoveal neovascular lesion with subretinal fluid, peripapillary neovascularization, epiretinal membrane, foveal cyst, choroidal folds, and drusen. Similar imaging was possible with the simplified setup. SDOCT imaging identified retinal disease of the posterior eyecup in human donor eyes. Pathology detected with SDOCT was verified by light microscopy in three eyes, supporting the utility of SDOCT as a screening tool for research.

Age-related macular degeneration (AMD) is a late-onset, neurodegenerative retinal disease that shares several clinical and pathological features with Alzheimer's disease (AD) including extracellular deposits containing amyloid-beta (Abeta) peptides. Immunotherapy targeting the Abeta protein has been investigated as a potential treatment for AD. Here, we present the rationale for extending this approach to treat AMD. We tested an anti-Abeta antibody administered systemically in a mouse model of AMD. Histological and functional measurements in treated animals compared to controls showed that following immunotherapy, the amounts of Abeta in the retina and brain were decreased and the ERG deficits in the retina were attenuated. These data support the hypothesis that Abeta is a therapeutic target for AMD.

Complement factor H (CFH) is a major susceptibility gene for age-related macular degeneration (AMD); however, its impact on AMD pathobiology is unresolved. Here, the role of CFH in the development of AMD pathology in vivo was interrogated by analyzing aged Cfh(+/-) and Cfh(-/-) mice fed a high-fat, cholesterol-enriched diet. Strikingly, decreased levels of CFH led to increased sub-retinal pigmented epithelium (sub-RPE) deposit formation, specifically basal laminar deposits, following high-fat diet. Mechanistically, our data show that deposits are due to CFH competition for lipoprotein binding sites in Bruch's membrane. Interestingly and despite sub-RPE deposit formation occurring in both Cfh(+/-) and Cfh(-/-) mice, RPE damage accompanied by loss of vision occurred only in old Cfh(+/-) mice. We demonstrate that such pathology is a function of excess complement activation in Cfh(+/-) mice versus complement deficiency in Cfh(-/-) animals. Due to the CFH-dependent increase in sub-RPE deposit height, we interrogated the potential of CFH as a previously unidentified regulator of Bruch's membrane lipoprotein binding and show, using human Bruch's membrane explants, that CFH removes endogenous human lipoproteins in aged donors. Thus, advanced age, high-fat diet, and decreased CFH induce sub-RPE deposit formation leading to complement activation, which contributes to RPE damage and visual function impairment. This new understanding of the complicated interactions of CFH in AMD-like pathology provides an improved foundation for the development of targeted therapies for AMD.

Choroidal neovascularization (CNV) is a debilitating complication of age-related macular degeneration and a leading cause of vision loss. Along with other angiogenic factors like vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF)-1 and its receptor, IGF-1R, have been implicated in CNV. IGF-1 is produced in neurons and retinal pigment epithelium (RPE) but its targets and impact in CNV are not understood. IGF-1 immunoreactivity was abundant throughout surgically isolated human CNV tissues and RPE cells were immunopositive for IGF-1R. Cultured RPE cells obtained from CNV tissues expressed IGF-1R. IGF-1 stimulation of cultured cells from CNV tissues induced monophasic sustained rises in intracellular free Ca(2+). VEGF concentration in the medium of unstimulated RPE cell cultures from CNV tissues increased with time to a steady-state (8h) which was increased twofold by IGF-1 stimulation. Thus, in RPE cells IGF-1 stimulates the second messenger Ca(2+) and increases VEGF secretion which, in turn, induces neovascularization.

Age-related macular degeneration (AMD) is a leading cause of visual dysfunction worldwide. Amyloid β (Aβ) peptides, Aβ1–40 (Aβ40) and Aβ1–42 (Aβ42), have been implicated previously in the AMD disease process. Consistent with a pathogenic role for Aβ, we show here that a mouse model of AMD that invokes multiple factors that are known to modify AMD risk (aged human apolipoprotein E 4 targeted replacement mice on a high-fat, cholesterol-enriched diet) presents with Aβ-containing deposits basal to the retinal pigmented epithelium (RPE), histopathologic changes in the RPE, and a deficit in scotopic electroretinographic response, which is reflective of impaired visual function. Strikingly, these electroretinographic deficits are abrogated in a dose-dependent manner by systemic administration of an antibody targeting the C termini of Aβ40 and Aβ42. Concomitant reduction in the levels of Aβ and activated complement components in sub-RPE deposits and structural preservation of the RPE are associated with anti-Aβ40/42 antibody immunotherapy and visual protection. These observations are consistent with the reduction in amyloid plaques and improvement of cognitive function in mouse models of Alzheimer's disease treated with anti-Aβ antibodies. They also implicate Aβ in the pathogenesis of AMD and identify Aβ as a viable therapeutic target for its treatment.

During the past ten years, dramatic advances have been made in unraveling the biological bases of age-related macular degeneration (AMD), the most common cause of irreversible blindness in western populations. In that timeframe, two distinct lines of evidence emerged which implicated chronic local inflammation and activation of the complement cascade in AMD pathogenesis. First, a number of complement system proteins, complement activators, and complement regulatory proteins were identified as molecular constituents of drusen, the hallmark extracellular deposits associated with early AMD. Subsequently, genetic studies revealed highly significant statistical associations between AMD and variants of several complement pathway-associated genes including: Complement factor H (CFH), complement factor H-related 1 and 3 (CFHR1 and CFHR3), complement factor B (CFB), complement component 2 (C2), and complement component 3 (C3). In this article, we revisit our original hypothesis that chronic local inflammatory and immune-mediated events at the level of Bruch's membrane play critical roles in drusen biogenesis and, by extension, in the pathobiology of AMD. Secondly, we report the results of a new screening for additional AMD-associated polymorphisms in a battery of 63 complement-related genes. Third, we identify and characterize the local complement system in the RPE-choroid complex - thus adding a new dimension of biological complexity to the role of the complement system in ocular aging and AMD. Finally, we evaluate the most salient, recent evidence that bears directly on the role of complement in AMD pathogenesis and progression. Collectively, these recent findings strongly re-affirm the importance of the complement system in AMD. They lay the groundwork for further studies that may lead to the identification of a transcriptional disease signature of AMD, and hasten the development of new therapeutic approaches that will restore the complement-modulating activity that appears to be compromised in genetically susceptible individuals.

Numerous genetic linkage studies have identified chromosomal regions associated with primarily familial development of myopia.1 In the present study, we evaluated pedigrees that mapped to the first identified locus for high myopia on chromosome X (MYP1, OMIM 310460).2 In a large pedigree reported in 1988, this locus was mapped to chromosome Xq27.3–28 by Schwartz et al.2–4 and Young et al.2–4 using restriction fragment-linked polymorphic markers. The family originated in Bornholm, Denmark, and the phenotype of Bornholm eye disease (BED) included high-grade myopia, amblyo-pia, optic nerve hypoplasia, subnormal dark-adapted electroretinographic (ERG) flicker function, and deuteranopia. In 2004, Young et al.4 reported another high-grade myopia phenotype in a family of Danish descent living in Minnesota that mapped to the Xq28 locus, with a similar phenotype of optic nerve hypoplasia with temporal pigmentary crescent, subnormal photopic ERG function, and protanopia rather than deuteranopia in the BED phenotype. We suggested that the phenotype was more consistent with an X-linked cone dysfunction than with simplex myopia. A recent replication report from the United Kingdom confirmed the X-linked cone dysfunction syndrome with an associated moderate to high myopia and protanopia phenotype.5 Although the X-linked myopia phenotypes are similar, a distinguishing feature is the type of color vision deficiency, which is deuteranopia in the BED pedigree and protanopia in the Minnesota and United Kingdom pedigrees. Interestingly, the visual cone pigment (opsin) genes, red (long wavelength [L]) and green (medium wavelength [M]), are present in tandem on the human X-chromosome at Xq28. In this opsin gene array, a single L, or red, gene is followed by one or more copies of the M, or green, gene in the normal color vision state.6,7 Alterations in this gene array with a red-green opsin hybrid gene in the first position or a green-red opsin hybrid in the second position are associated with protan and deutan color vision defects, respectively.7,8 Young et al.4 performed single-stranded conformational polymorphism analysis to determine the ratio of red to green promoters in the BED and Minnesota pedigrees. We previously determined that affected and unaffected males in both pedigrees had four and three opsin genes, respectively, and reported that known reported hybrid opsin genes are responsible for the respective color vision deficiencies.4 The opsin gene array represents a region of repetitive DNA segments termed segmental duplications. The segmental duplications involving opsin genes encompass the testis-expressed protein 28 gene (TEX28), also known as chromosome X open-reading frame 2 (CXorf2), a nested gene within the cone opsin pigment gene array.9 TEX28 is composed of five exons that almost span the entire distance between the protein-coding regions of the opsin genes and the transketolase-related type 1 gene (TKTL1), and it encodes a polypeptide of 410 amino acid residues (Fig. 1). Few studies of TEX28 have been reported in the literature, and its involvement in the X-linked myopia phenotypes is unknown.10,11 The reported number of normal repetitive copies of TEX28 is three, intercalated within and translated in the opposite (3′ to 5′) direction from the opsin gene array.9 Figure 1 Schematic representation of the arrangement of opsin gene array and TEX28 genes at the chromosome Xq28 locus (source, UCSC Genome Browser [http://genome.ucsc.edu/]). OPN1LW, red cone pigment gene; OPN1MW, green cone pigment gene; TKTL1, transketolase-related ... Because of the consistent color vision deficiencies in all reported MYP1 pedigrees, we hypothesized that the X-linked MYP1 myopia phenotype could be caused by TEX28 sequence alterations or copy number variation (CNV). This was determined using fine mapping array comparative genomic hybridization (array-CGH) and real-time quantitative polymerase chain reaction (RT-qPCR) assays. Sequence mutation screening, genetic association, and gene expression studies were also performed.

Macular translocation with 360-degree peripheral retinectomy (MT360) is used to rotate the fovea away from a bed of choroidal neovascularization (CNV) or atrophy onto a bed of healthier retinal pigment epithelium (RPE) and choriocapillaris. Often, the fovea recovers function over this healthier RPE and the patient improves in distance and near visual acuity, reading speed and quality of life.1–3 The Duke Macular Translocation Study is a prospective, noncomparative study of MT360 for neovascular age-related macular degeneration (AMD) in the second eye. Of the 64 patients enrolled in the study, median visual acuity of the study eye was 20/125 before treatment, and the median lesion size was nine macular photocoagulation study (MPS) disk areas (range 3–30 MPS disk areas). At 1 and 2 years after surgery, the median visual acuity of the study eyes improved to 20/80.1,4 Although geographic atrophy has been reported in the new subfoveal RPE after MT360,5,6 there is little data regarding whether repositioning the macula off CNV will initiate the rapid onset or progression of AMD in the new subfoveal RPE bed that was previously outside the macula. The purpose of this study was to evaluate the RPE at the site of the translocated fovea for signs of new subfoveal drusen, geographic atrophy, or new CNV, and to evaluate factors associated with AMD clinical progression.

NEIBank is an integrated resource for genomics and bioinformatics in vision research. It includes expressed sequence tag (EST) data and sequence-verified cDNA clones for multiple eye tissues of several species, web-based access to human eye-specific SAGE data through EyeSAGE, and comprehensive, annotated databases of known human eye disease genes and candidate disease gene loci. All expression- and disease-related data are integrated in EyeBrowse, an eye-centric genome browser. NEIBank provides a comprehensive overview of current knowledge of the transcriptional repertoires of eye tissues and their relation to pathology.

Age-related macular degeneration (AMD) is a late-onset, neurodegenerative disease of the retina and is the leading cause of catastrophic vision loss in the elderly. AMD usually occurs in people over the age of 65 years (Javitt et al., 2003) and accounts for approximately 50% of registered blindness in Western Europe and North America (Mitchell et al., 1998; Vingerling et al., 1995a). It develops as either dry AMD, geographic atrophy, or wet AMD (exudative) (Bird et al., 1995; Green, 1999). Dry AMD is characterized by the presence of sub-retinal pigment epithelium (RPE) deposits including drusen, basal linear deposits and basal laminar deposits (Curcio and Millican, 1999; Sarks, 1976). Geographic atrophy is characterized by RPE atrophy and wet or exudative AMD is characterized by choroidal neovascularization (CNV) (1991) and more recently, retinal angiomatous proliferation (Yannuzzi et al., 2001). In AMD with CNV, tufts of newly formed, functionally incompetent, blood vessels proliferate from the choroid, break through a thickened and fragile Bruch’s membrane (Grossniklaus and Green, 2004), and extend laterally into the sub-RPE (Sarks et al., 1980; Tobe et al., 1998a). These vessels in turn, may erode through the RPE, infiltrate the neural sensory retina, and communicate with the retinal circulation in what has been referred to as a retinal-choroidal anastomosis. This is common in the end stage of disciform disease (Yannuzzi et al., 2001).

The macula is a highly specialized region of the primate retina that contains the highest densities of rod and cone photoreceptors, as well as the second-order neurons and ganglion cells that receive input from the photoreceptors. Because it encompasses the cone-enriched fovea, which mediates high-acuity central vision, diseases affecting the macula have devastating sight-related consequences. In fact, age-related macular degeneration (AMD) is the leading cause of untreatable new vision loss in the elderly, affecting more than 14 million patients in the United States alone.1–3 Macular degenerations are characterized by dysfunction and, ultimately, the death of rod and cone photoreceptors and the adjacent retinal pigment epithelium (RPE). The mechanism of cone loss is poorly understood, but it appears that foveal cones, in particular, have a capacity for survival in a region of the retina with a propensity for degeneration.4–7 The macula also contains the highest concentration of retinal ganglion cells (RGCs), whose death is responsible for the vision loss associated with glaucoma. We hypothesize that differential gene expression contributes to the establishment of the unique macular microenvironment and is crucial to maintaining the health of this region. Expression profiling of the macula should reveal genes that may contribute to disease susceptibility and others that enhance photoreceptor survival. Gene expression profiling in the human macula is complicated by the technical difficulties inherent in isolating RNA from human donor tissue and is further confounded by the presence of pigmented RPE cells (for an excellent review of these technical hurdles, please see Chowers et al.8). Recent technical advances in large-scale, RNA-based technologies and analysis strategies (e.g., microarray technologies and serial analysis of gene expression, or SAGE9), have vastly increased the extent of the transcriptome that can be uncovered from small amounts of starting material. SAGE is a powerful technique that provides quantitative and comprehensive gene expression profiling.9 Conventional or shortSAGE uses short 14-bp tags of internal transcript signatures9 to identify and quantify individual gene transcripts. We describe the construction of four new shortSAGE libraries representing topographic regions of human retina and RPE/choroid, as well as the first retinal longSAGE library. LongSAGE produces 21-bp transcript tags that, owing to its increased tag length, can be used for direct assignment to genome sequences and for identification of novel genes and alternative transcripts.10,11 Analysis of the human retina and RPE transcriptomes has been approached using a wide array of large-scale expression profiling methodologies (please see Refs. 12,13 for reviews), including SAGE14 and microarrays8,15–17 used here and suppression subtraction hybridization.12 These studies have been instrumental in developing knowledge of the retina and RPE transcriptomes. To enhance the utility of these data we created EyeSAGE, a relational database for the analysis and presentation of human retina and RPE/choroid SAGE and microarray expression profiles, compared with transcript expression in the human body or brain. The unique strength of the EyeSAGE database is that by examining the tissue-specific patterns of gene expression, we are able to identify sets of transcripts that are characteristic of subpopulations of cells within the retina, including cell populations that would be difficult or impossible to isolate physically. By combining these cell-type–specific expression profiles with the results of genomic linkage studies, we have identified candidate genes for a variety of ocular genetic disorders. The EyeSAGE database is posted at the National Eye Institute's NEIBank Web site (http://neibank.nei.nih.gov/index.shtml/ provided in the public domain by the National Eye Institute, Bethesda, MD) and the candidate retinal disease gene expression tables are also available at our Web site (http://www.duke.edu/~bowes007/EyeSAGE.htm/ provided in the public domain by Duke University, Durham, NC), as well as through RetNet (http://www.sph.uth.tmc.edu/RetNet/ provided in the public domain by the University of Texas Houston Health Science Center, Houston, TX).

To assess the prevalence of recurrence of macular geographic atrophy (GA) of the retinal pigment epithelium (RPE) after macular translocation with 360 degrees retinectomy (MT360) in one institution.A retrospective review of all cases of GA that were treated with MT360 in 1 institution. Demographic and clinical data including the duration of preoperative visual loss, preoperative and postoperative visual acuity, and the prevalence of postoperative foveal RPE atrophy were recorded for these patients, and these data were compared with similar data from patients who underwent MT360 for neovascular age-related macular degeneration (AMD) as part of the prospective Duke Macular Translocation Study, Duke University Eye Center, Durham, NC.Four eyes in 4 patients with GA secondary to AMD underwent MT360 and were compared with 63 eyes in 63 patients who underwent MT360 for neovascular AMD as part of the Duke Macular Translocation Study. The mean duration of preoperative visual loss was higher in the GA group (11.3 months) than in the neovascular AMD group (1.7 months) (P = .08). The prevalence of postoperative foveal RPE atrophy was significantly higher in the GA group (n = 3; 75.0%) than in the neovascular AMD group (n = 5; 8.3%) (P.01); in the GA group, this corresponded to recurrence of the GA lesions. In contrast, the postoperative RPE atrophy seen in the neovascular AMD group was due to postoperative mechanical forces such as laser therapy or RPE tearing. There was no significant difference in the mean preoperative or postoperative visual acuity in either group.Subfoveal RPE atrophy can reoccur following MT360 in eyes with nonneovascular AMD and GA; RPE atrophy similar to this has not been found in a large consecutive series of patients with neovascular AMD after MT360. Further research is needed to assess if the potential for visual recovery in eyes with end-stage nonneovascular AMD is outweighed by the possibility of postoperative recurrence of GA.

Age-related macular degeneration is the leading cause of irreversible visual dysfunction in individuals over 65 in Western Society. Patients with AMD are classified as having early stage disease (early AMD), in which visual function is affected, or late AMD (generally characterized as either “wet” neovascular AMD, “dry” atrophic AMD or both), in which central vision is severely compromised or lost. Until recently, there have been no therapies available to treat the disorder(s). Now, the most common wet form of late-stage AMD, choroidal neovascularization, generally responds to treatment with anti–vascular endothelial growth factor therapies. Nevertheless, there are no current therapies to restore lost vision in eyes with advanced atrophic AMD. Oral supplementation with the Age-Related Eye Disease Study (AREDS) or AREDS2 formulation (antioxidant vitamins C and E, lutein, zeaxanthin, and zinc) has been shown to reduce the risk of progression to advanced AMD, although the impact was in neovascular rather than atrophic AMD. Recent findings, however, have demonstrated several features of early AMD that are likely to be druggable targets for treatment. Studies have established that much of the genetic risk for AMD is associated with complement genes. Consequently, several complement-based therapeutic treatment approaches are being pursued. Potential treatment strategies against AMD deposit formation and protein and/or lipid deposition will be discussed, including anti-amyloid therapies. In addition, the role of autophagy in AMD and prevention of oxidative stress through modulation of the antioxidant system will be explored. Finally, the success of these new therapies in clinical trials and beyond relies on early detection, disease typing, and predicting disease progression, areas that are currently being rapidly transformed by improving imaging modalities and functional assays.

Foveal cone photoreceptors are morphologically distinct and, presumably, express unique transcripts. We have identified a cDNA clone encoding the protein tyrosine phosphatase (PTP), phosphatase of regenerating liver 1 (PRL-1) in a screen for genes that are enriched in monkey fovea. PRL-1 was originally isolated as an immediate early gene in regenerating liver [R.H. Diamond, D.E. Cressman, T.M. Laz, C.S. Abrams, R. Taub, PRL-1, a unique nuclear protein tyrosine phosphatase, affects cell growth, Mol. Cell Biol. 14 (1994) 3752–3762]. On cDNA Southern blots of human and monkey retina, radiolabeled PRL-1 cDNA hybridized to a single mRNA species of about 2.5 kb that was most intense in fovea-enriched samples. The monkey PRL-1 deduced amino acid sequence is identical to human, rat and mouse PRL-1. Affinity-purified antibodies directed against PRL-1 preferentially labeled cone photoreceptor cells and a subpopulation of bipolar cells in monkey retina. Immunoreactivity in cones was confined to red and green, but not to blue, cones and was restricted to the outer segments. Immunolocalization also revealed that PRL-1 protein expression was non-nuclear, suggesting that its function in the retina may be unrelated to its role in other tissues where it is expressed primarily in nuclei. Although both foveal and extrafoveal cones were PRL-1 reactive, the high abundance of PRL-1 mRNAs detected in monkey fovea correlates with the high concentration of cones in the fovea. The PRL-1 gene is located on chromosome 6q within an interval that also contains the genes that cause two hereditary retinal dystrophies. These studies demonstrate novel expression of the PRL-1 gene in the neural retina and suggest the phosphatase activity of PRL-1 may modulate normal cone photoreceptor cell function.

The phosphatase of regenerating liver-1, PRL-1, gene was detected in a screen for foveal cone photoreceptor-associated genes. It encodes a small protein tyrosine phosphatase that was previously immunolocalized to the photoreceptors in primate retina. Here we report that in cones and cone-derived cultured cells both PRL-1 activity and PRL-1 gene expression are modulated under oxidative stress. Oxidation reversibly inhibited the phosphatase activity of PRL-1 due to the formation of an intramolecular disulfide bridge between Cys104 within the active site and another conserved Cys, Cys49. This modulation was observed in vitro, in cell culture and in isolated retinas exposed to hydrogen peroxide. The same treatment caused a rapid increase in PRL-1 expression levels in cultured cells which could be blocked by the protein translation inhibitor, cycloheximide. Increased PRL-1 expression was also observed in living rats subjected to constant light exposure inducing photooxidative stress. We further demonstrated that both oxidation and overexpression of PRL-1 upon oxidative stress are greatly enhanced by inhibition of the glutathione system responsible for cellular redox regulation. These findings suggest that PRL-1 is a molecular component of the photoreceptor's response to oxidative stress acting upstream of the glutathione system.