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Grubaugh CR, Dhingra A, Prakash B, Montenegro D, Sparrow JR, Daniele LL, Curcio CA, Bell BA, Hussain MM, Boesze-Battaglia K. Microsomal triglyceride transfer protein is necessary to maintain lipid homeostasis and retinal function. FASEB J 2024; 38:e23522. [PMID: 38445789 PMCID: PMC10949407 DOI: 10.1096/fj.202302491r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Revised: 02/07/2024] [Accepted: 02/16/2024] [Indexed: 03/07/2024]
Abstract
Lipid processing by the retinal pigment epithelium (RPE) is necessary to maintain retinal health and function. Dysregulation of retinal lipid homeostasis due to normal aging or age-related disease triggers lipid accumulation within the RPE, on Bruch's membrane (BrM), and in the subretinal space. In its role as a hub for lipid trafficking into and out of the neural retina, the RPE packages a significant amount of lipid into lipid droplets for storage and into apolipoprotein B (APOB)-containing lipoproteins (Blps) for export. Microsomal triglyceride transfer protein (MTP), encoded by the MTTP gene, is essential for Blp assembly. Herein we test the hypothesis that MTP expression in the RPE is essential to maintain lipid balance and retinal function using the newly generated RPEΔMttp mouse model. Using non-invasive ocular imaging, electroretinography, and histochemical and biochemical analyses we show that genetic depletion of Mttp from the RPE results in intracellular lipid accumulation, increased photoreceptor-associated cholesterol deposits, and photoreceptor cell death, and loss of rod but not cone function. RPE-specific reduction in Mttp had no significant effect on plasma lipids and lipoproteins. While APOB was decreased in the RPE, most ocular retinoids remained unchanged, with the exception of the storage form of retinoid, retinyl ester. Thus suggesting that RPE MTP is critical for Blp synthesis and assembly but is not directly involved in plasma lipoprotein metabolism. These studies demonstrate that RPE-specific MTP expression is necessary to establish and maintain retinal lipid homeostasis and visual function.
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Affiliation(s)
- Catharina R. Grubaugh
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Anuradha Dhingra
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Binu Prakash
- Department of Foundations of Medicine, New York University Grossman Long Island School of Medicine, Mineola, NY, 11501 USA
| | - Diego Montenegro
- Department of Ophthalmology and Department of Pathology and Cell Biology, Columbia University, New York, NY, 10027 USA
| | - Janet R. Sparrow
- Department of Ophthalmology and Department of Pathology and Cell Biology, Columbia University, New York, NY, 10027 USA
| | - Lauren L. Daniele
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Christine A. Curcio
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Brent A. Bell
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA, 19104 USA
| | - M. Mahmood Hussain
- Department of Foundations of Medicine, New York University Grossman Long Island School of Medicine, Mineola, NY, 11501 USA
| | - Kathleen Boesze-Battaglia
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
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2
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Grubaugh CR, Dhingra A, Prakash B, Montenegro D, Sparrow JR, Daniele LL, Curcio CA, Bell BA, Hussain MM, Boesze-Battaglia K. Microsomal triglyceride transfer protein is necessary to maintain lipid homeostasis and retinal function. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.06.570418. [PMID: 38105975 PMCID: PMC10723417 DOI: 10.1101/2023.12.06.570418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Lipid processing by the retinal pigment epithelium (RPE) is necessary to maintain retinal health and function. Dysregulation of retinal lipid homeostasis due to normal aging or to age-related disease triggers lipid accumulation within the RPE, on Bruch's membrane (BrM), and in the subretinal space. In its role as a hub for lipid trafficking into and out of the neural retina, the RPE packages a significant amount of lipid into lipid droplets for storage and into apolipoprotein B (apoB)-containing lipoproteins (Blps) for export. Microsomal triglyceride transfer protein (MTP), encoded by the MTTP gene, is essential for Blp assembly. Herein we test the hypothesis that MTP expression in the RPE is essential to maintain lipid balance and retinal function using the newly generated RPEΔMttp mouse model. Using non-invasive ocular imaging, electroretinography, and histochemical and biochemical analyses we show that genetic deletion of Mttp from the RPE results in intracellular lipid accumulation, increased photoreceptor -associated cholesterol deposits and photoreceptor cell death, and loss of rod but not cone function. RPE-specific ablation of Mttp had no significant effect on plasma lipids and lipoproteins. While, apoB was decreased in the RPE, ocular retinoid concentrations remained unchanged. Thus suggesting that RPE MTP is critical for Blp synthesis and assembly but not directly involved in ocular retinoid and plasma lipoprotein metabolism. These studies demonstrate that RPE-specific MTP expression is necessary to establish and maintain retinal lipid homeostasis and visual function.
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Affiliation(s)
- Catharina R. Grubaugh
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Anuradha Dhingra
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Binu Prakash
- Department of Foundations of Medicine, New York University Grossman Long Island School of Medicine, Mineola, NY, 11501 USA
| | - Diego Montenegro
- Department of Ophthalmology and Department of Pathology and Cell Biology, Columbia University, New York, NY,10027 USA
| | - Janet R. Sparrow
- Department of Ophthalmology and Department of Pathology and Cell Biology, Columbia University, New York, NY,10027 USA
| | - Lauren L. Daniele
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Christine A. Curcio
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Brent A. Bell
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA, 19104 USA
| | - M. Mahmood Hussain
- Department of Foundations of Medicine, New York University Grossman Long Island School of Medicine, Mineola, NY, 11501 USA
| | - Kathleen Boesze-Battaglia
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
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3
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Gnanaguru G, Mackey A, Choi EY, Arta A, Rossato FA, Gero TW, Urquhart AJ, Scott DA, D'Amore PA, Ng YSE. Discovery of sterically-hindered phenol compounds with potent cytoprotective activities against ox-LDL-induced retinal pigment epithelial cell death as a potential pharmacotherapy. Free Radic Biol Med 2022; 178:360-368. [PMID: 34843917 PMCID: PMC8758799 DOI: 10.1016/j.freeradbiomed.2021.11.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 10/22/2021] [Accepted: 11/19/2021] [Indexed: 01/03/2023]
Abstract
Late-stage dry age-related macular degeneration (AMD) or geographic atrophy (GA) is an irreversible blinding condition characterized by degeneration of retinal pigment epithelium (RPE) and the associated photoreceptors. Clinical and genetic evidence supports a role for dysfunctional lipid processing and accumulation of harmful oxidized lipids in the pathogenesis of GA. Using an oxidized low-density lipoprotein (ox-LDL)-induced RPE death assay, we screened and identified sterically-hindered phenol compounds with potent protective activities for RPE. The phenol-containing PPARγ agonist, troglitazone, protected against ox-LDL-induced RPE cell death, whereas other more potent PPARγ agonists did not protect RPE cells. Knockdown of PPARγ did not affect the protective activity of troglitazone in RPE, confirming the protective function is not due to the thiazolidine (TZD) group of troglitazone. Prototypical hindered phenol trolox and its analogs potently protected against ox-LDL-induced RPE cell death whereas potent antioxidants without the phenol group failed to protect RPE. Hindered phenols preserved lysosomal integrity against ox-LDL-induced damage and FITC-labeled trolox was localized to the lysosomes in RPE cells. Analogs of trolox inhibited reactive oxygen species (ROS) formation induced by ox-LDL uptake in a dose-dependent fashion and were effective at sub-micromolar concentrations. Treatment with trolox analog 2,2,5,7,8-pentamethyl-6-chromanol (PMC) significantly induced the expression of the lysosomal protein NPC-1 and reduced intracellular cholesterol level upon ox-LDL uptake. Our data indicate that the lysosomal-localized hindered phenols are uniquely potent in protecting the RPE against the toxic effects of ox-LDL, and may represent a novel pharmacotherapy to preserve the vision in patients with GA.
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Affiliation(s)
- Gopalan Gnanaguru
- Harvard Ophthalmology, Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, MA, USA
| | - Ashley Mackey
- Harvard Ophthalmology, Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, MA, USA
| | - Eun Young Choi
- Harvard Ophthalmology, Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, MA, USA
| | - Anthoula Arta
- Harvard Ophthalmology, Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, MA, USA; Department of Health Technology, Institut for Sundhedsteknologi, Lyngby, Denmark
| | - Franco Aparecido Rossato
- Harvard Ophthalmology, Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, MA, USA
| | - Thomas W Gero
- Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Ave, Boston, MA, 02215, USA
| | - Andrew J Urquhart
- Department of Health Technology, Institut for Sundhedsteknologi, Lyngby, Denmark
| | - David A Scott
- Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Ave, Boston, MA, 02215, USA
| | - Patricia A D'Amore
- Harvard Ophthalmology, Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, MA, USA
| | - Yin Shan E Ng
- Harvard Ophthalmology, Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, MA, USA.
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4
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Landowski M, Bowes Rickman C. Targeting Lipid Metabolism for the Treatment of Age-Related Macular Degeneration: Insights from Preclinical Mouse Models. J Ocul Pharmacol Ther 2021; 38:3-32. [PMID: 34788573 PMCID: PMC8817708 DOI: 10.1089/jop.2021.0067] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
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.
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Affiliation(s)
- Michael Landowski
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, Wisconsin, USA.,McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Catherine Bowes Rickman
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, USA.,Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, USA
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Brown CN, Green BD, Thompson RB, den Hollander AI, Lengyel I. Metabolomics and Age-Related Macular Degeneration. Metabolites 2018; 9:metabo9010004. [PMID: 30591665 PMCID: PMC6358913 DOI: 10.3390/metabo9010004] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 12/17/2018] [Accepted: 12/20/2018] [Indexed: 12/11/2022] Open
Abstract
Age-related macular degeneration (AMD) leads to irreversible visual loss, therefore, early intervention is desirable, but due to its multifactorial nature, diagnosis of early disease might be challenging. Identification of early markers for disease development and progression is key for disease diagnosis. Suitable biomarkers can potentially provide opportunities for clinical intervention at a stage of the disease when irreversible changes are yet to take place. One of the most metabolically active tissues in the human body is the retina, making the use of hypothesis-free techniques, like metabolomics, to measure molecular changes in AMD appealing. Indeed, there is increasing evidence that metabolic dysfunction has an important role in the development and progression of AMD. Therefore, metabolomics appears to be an appropriate platform to investigate disease-associated biomarkers. In this review, we explored what is known about metabolic changes in the retina, in conjunction with the emerging literature in AMD metabolomics research. Methods for metabolic biomarker identification in the eye have also been discussed, including the use of tears, vitreous, and aqueous humor, as well as imaging methods, like fluorescence lifetime imaging, that could be translated into a clinical diagnostic tool with molecular level resolution.
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Affiliation(s)
- Connor N Brown
- Wellcome-Wolfson Institute for Experimental Medicine (WWIEM), Queen's University Belfast, Belfast BT9 7BL, UK.
| | - Brian D Green
- Institute for Global Food Security (IGFS), Queen's University Belfast, Belfast BT9 6AG, UK.
| | - Richard B Thompson
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Maryland, Baltimore, MD 21201, USA.
| | - Anneke I den Hollander
- Department of Ophthalmology, Radboud University Nijmegen Medical Centre, Nijmegen 6525 EX, The Netherlands.
| | - Imre Lengyel
- Wellcome-Wolfson Institute for Experimental Medicine (WWIEM), Queen's University Belfast, Belfast BT9 7BL, UK.
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Roizenblatt M, Naranjit N, Maia M, Gehlbach PL. The Question of a Role for Statins in Age-Related Macular Degeneration. Int J Mol Sci 2018; 19:ijms19113688. [PMID: 30469381 PMCID: PMC6274767 DOI: 10.3390/ijms19113688] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 11/18/2018] [Accepted: 11/19/2018] [Indexed: 01/22/2023] Open
Abstract
Age-related macular degeneration (AMD) is the leading cause of irreversible central vision loss in patients over the age of 65 years in industrialized countries. Epidemiologic studies suggest that high dietary fat intake is a risk factor for the development and progression of both vascular and retinal disease. These, and other associations, suggest a hypothesis linking elevated cholesterol and AMD progression. It follows, therefore, that cholesterol-lowering medications, such as statins, may influence the onset and progression of AMD. However, the findings have been inconclusive as to whether statins play a role in AMD. Due to the significant public health implications of a potential inhibitory effect of statins on the onset and progression of AMD, it is important to continually evaluate emerging findings germane to this question.
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Affiliation(s)
- Marina Roizenblatt
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
- Department of Ophthalmology, Federal University of São Paulo, São Paulo 04023-062, Brazil.
- Vision Institute, IPEPO, Department of Ophthalmology, Paulista Medical School, Federal University of São Paulo, São Paulo 04038-032, Brazil.
| | - Nara Naranjit
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
| | - Mauricio Maia
- Department of Ophthalmology, Federal University of São Paulo, São Paulo 04023-062, Brazil.
- Vision Institute, IPEPO, Department of Ophthalmology, Paulista Medical School, Federal University of São Paulo, São Paulo 04038-032, Brazil.
| | - Peter L Gehlbach
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
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Curcio CA. Soft Drusen in Age-Related Macular Degeneration: Biology and Targeting Via the Oil Spill Strategies. Invest Ophthalmol Vis Sci 2018; 59:AMD160-AMD181. [PMID: 30357336 PMCID: PMC6733535 DOI: 10.1167/iovs.18-24882] [Citation(s) in RCA: 173] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
AMD is a major cause of legal blindness in older adults approachable through multidisciplinary research involving human tissues and patients. AMD is a vascular-metabolic-inflammatory disease, in which two sets of extracellular deposits, soft drusen/basal linear deposit (BLinD) and subretinal drusenoid deposit (SDD), confer risk for end-stages of atrophy and neovascularization. Understanding how deposits form can lead to insights for new preventions and therapy. The topographic correspondence of BLinD and SDD with cones and rods, respectively, suggest newly realized exchange pathways among outer retinal cells and across Bruch's membrane and the subretinal space, in service of highly evolved, eye-specific physiology. This review focuses on soft drusen/BLinD, summarizing evidence that a major ultrastructural component is large apolipoprotein B,E-containing, cholesterol-rich lipoproteins secreted by the retinal pigment epithelium (RPE) that offload unneeded lipids of dietary and outer segment origin to create an atherosclerosis-like progression in the subRPE-basal lamina space. Clinical observations and an RPE cell culture system combine to suggest that soft drusen/BLinD form when secretions of functional RPE back up in the subRPE-basal lamina space by impaired egress across aged Bruch's membrane-choriocapillary endothelium. The soft drusen lifecycle includes growth, anterior migration of RPE atop drusen, then collapse, and atrophy. Proof-of-concept studies in humans and animal models suggest that targeting the “Oil Spill in Bruch's membrane” offers promise of treating a process in early AMD that underlies progression to both end-stages. A companion article addresses the antecedents of soft drusen within the biology of the macula.
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Affiliation(s)
- Christine A Curcio
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
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Mitchell P, Liew G, Gopinath B, Wong TY. Age-related macular degeneration. Lancet 2018; 392:1147-1159. [PMID: 30303083 DOI: 10.1016/s0140-6736(18)31550-2] [Citation(s) in RCA: 857] [Impact Index Per Article: 142.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 06/12/2018] [Accepted: 06/29/2018] [Indexed: 12/13/2022]
Abstract
Age-related macular degeneration is a leading cause of visual impairment and severe vision loss. Clinically, it is classified as early-stage (medium-sized drusen and retinal pigmentary changes) to late-stage (neovascular and atrophic). Age-related macular degeneration is a multifactorial disorder, with dysregulation in the complement, lipid, angiogenic, inflammatory, and extracellular matrix pathways implicated in its pathogenesis. More than 50 genetic susceptibility loci have been identified, of which the most important are in the CFH and ARMS2 genes. The major non-genetic risk factors are smoking and low dietary intake of antioxidants (zinc and carotenoids). Progression from early-stage to late-stage disease can be slowed with high-dose zinc and antioxidant vitamin supplements. Intravitreal anti-vascular endothelial growth factor therapy (eg, ranibizumab, aflibercept, or bevacizumab) is highly effective at treating neovascular age-related macular degeneration, and has markedly decreased the prevalence of visual impairment in populations worldwide. Currently, no proven therapies for atrophic disease are available, but several agents are being investigated in clinical trials. Future progress is likely to be from improved efforts in prevention and risk-factor modification, personalised medicine targeting specific pathways, newer anti-vascular endothelial growth factor agents or other agents, and regenerative therapies.
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Affiliation(s)
- Paul Mitchell
- Centre for Vision Research, Department of Ophthalmology, Westmead Institute for Medical Research, University of Sydney, Australia.
| | - Gerald Liew
- Centre for Vision Research, Department of Ophthalmology, Westmead Institute for Medical Research, University of Sydney, Australia
| | - Bamini Gopinath
- Centre for Vision Research, Department of Ophthalmology, Westmead Institute for Medical Research, University of Sydney, Australia
| | - Tien Y Wong
- Singapore Eye Research Institute, Singapore National Eye Centre, Duke-National University of Singapore, Singapore
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Complement factor H in AMD: Bridging genetic associations and pathobiology. Prog Retin Eye Res 2017; 62:38-57. [PMID: 28928087 DOI: 10.1016/j.preteyeres.2017.09.001] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 09/08/2017] [Accepted: 09/13/2017] [Indexed: 01/28/2023]
Abstract
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.
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Kaszubski P, Ben Ami T, Saade C, Smith RT. Geographic Atrophy and Choroidal Neovascularization in the Same Eye: A Review. Ophthalmic Res 2016; 55:185-93. [PMID: 26871899 PMCID: PMC4845740 DOI: 10.1159/000443209] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 12/07/2015] [Indexed: 12/28/2022]
Abstract
Geographic atrophy (GA) and choroidal neovascularization (CNV), the two late forms of age-related macular degeneration, are generally considered two distinct entities. However, GA and CNV can occur simultaneously in the same eye, with GA usually occurring first. The prevalence of this combined entity is higher in histological studies than in clinical studies. No distinct systemic or genetic risk characteristics are associated with the combined GA/CNV entity, although on clinical examination and retinal imaging it can feature drusen or subretinal drusenoid deposits. GA and CNV may exist within the spectrum of a single disease, or they may be two very different diseases. Therapy with antivascular endothelial growth factor (anti-VEGF) is often successful for CNV, but some evidence suggests increased rates of GA development in eyes treated with anti-VEGF. In this article, we review the current literature regarding the epidemiology, clinical presentation, and treatment options for patients with the combined GA/CNV entity.
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Affiliation(s)
- Patrick Kaszubski
- Department of Ophthalmology, New York University School of Medicine, New York, N.Y., USA
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11
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Clinically detectable drusen domains in fibulin-5-associated age-related macular degeneration (AMD) : Drusen subdomains in fibulin-5 AMD. Int Ophthalmol 2015; 36:569-75. [PMID: 26694911 DOI: 10.1007/s10792-015-0164-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 12/13/2015] [Indexed: 10/22/2022]
Abstract
To evaluate whether drusen of subjects with fibulin-5 mutation-associated age-related macular degeneration (AMD) have clinically demonstrable drusen domains as evidenced by differences between color and fluorescein angiographic profiles. Of seven patients we identified with AMD due to mutations in the fibulin-5 gene (Fib-5 AMD), five had color fundus photography and fluorescein angiography (FA). One had bilateral choroidal neovascularization and no drusen. For each eye, the green channel (GC) of the digital RGB (Red-Green-Blue) color image and hyperfluorescent domain (HD) intensity of the FA image were registered and drusen were manually segmented and measured. Totally 75 small (≤62 μm), 110 intermediate (63-125 μm), and 30 large (>125 μm) drusen were measured in four patients within the 6 × 6 mm central macular areas. All four subjects demonstrated central or paracentral HDs within each drusen perimeter. HDs were found in association with each druse, with a HD/GC ratio of 0.82, 0.76, and 0.72 respectively for small, intermediate, and large drusen (Student T Test: P < 0.01, P < 0.01, P < 0.01). A statistical difference was found for the HD/GC ratios between small- and intermediate-sized drusen and small- and large-sized drusen but not between intermediate-sized and large-sized drusen (P = 0.001, P < 0.001, P > 0.05, respectively). AMD patients with mutations in fibulin-5 share drusen phenotypic structure and have HD/GC ratios that are similar to individuals with cuticular or basal laminar drusen. Drusen substructure may reflect similarities in drusen stage and/or genesis and appear to vary among AMD genotypes.
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12
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Abstract
SIGNIFICANCE A diverse family of lipid-derived levulinaldehydes, isolevuglandins (isoLGs), is produced by rearrangement of endoperoxide intermediates generated through both cyclooxygenase (COX) and free radical-induced cyclooxygenation of polyunsaturated fatty acids and their phospholipid esters. The formation and reactions of isoLGs with other biomolecules has been linked to alcoholic liver disease, Alzheimer's disease, age-related macular degeneration, atherosclerosis, cardiac arythmias, cancer, end-stage renal disease, glaucoma, inflammation of allergies and infection, mitochondrial dysfunction, multiple sclerosis, and thrombosis. This review chronicles progress in understanding the chemistry of isoLGs, detecting their production in vivo and understanding their biological consequences. CRITICAL ISSUES IsoLGs have never been isolated from biological sources, because they form adducts with primary amino groups of other biomolecules within seconds. Chemical synthesis enabled investigation of isoLG chemistry and detection of isoLG adducts present in vivo. RECENT ADVANCES The first peptide mapping and sequencing of an isoLG-modified protein present in human retina identified the modification of a specific lysyl residue of the sterol C27-hydroxylase Cyp27A1. This residue is preferentially modified by iso[4]LGE2 in vitro, causing loss of function. Adduction of less than one equivalent of isoLG can induce COX-associated oligomerization of the amyloid peptide Aβ1-42. Adduction of isoLGE2 to phosphatidylethanolamines causes gain of function, converting them into proinflammatory isoLGE2-PE agonists that foster monocyte adhesion to endothelial cells. FUTURE DIRECTIONS Among the remaining questions on the biochemistry of isoLGs are the dependence of biological activity on isoLG isomer structure, the structures and mechanism of isoLG-derived protein-protein and DNA-protein cross-link formation, and its biological consequences.
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Affiliation(s)
- Robert G Salomon
- Department of Chemistry, Case Western Reserve University, Cleveland, Ohio
| | - Wenzhao Bi
- Department of Chemistry, Case Western Reserve University, Cleveland, Ohio
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13
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HYPERREFLECTIVE PYRAMIDAL STRUCTURES ON OPTICAL COHERENCE TOMOGRAPHY IN GEOGRAPHIC ATROPHY AREAS. Retina 2014; 34:1524-30. [DOI: 10.1097/iae.0000000000000165] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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14
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Meadway A, Wang X, Curcio CA, Zhang Y. Microstructure of subretinal drusenoid deposits revealed by adaptive optics imaging. BIOMEDICAL OPTICS EXPRESS 2014; 5:713-27. [PMID: 24688808 PMCID: PMC3959830 DOI: 10.1364/boe.5.000713] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 01/18/2014] [Accepted: 02/05/2014] [Indexed: 05/18/2023]
Abstract
Subretinal drusenoid deposits (SDD), a recently recognized lesion associated with progression of age-related macular degeneration, were imaged with adaptive optics scanning laser ophthalmoscopy (AO-SLO) and optical coherence tomography (AO-OCT). AO-SLO revealed a distinct en face structure of stage 3 SDD, showing a hyporeflective annulus surrounded reflective core packed with hyperreflective dots bearing a superficial similarity to the photoreceptors in the unaffected retina. However, AO-OCT suggested that the speckled appearance over the SDD rendered by AO-SLO was the lesion material itself, rather than photoreceptors. AO-OCT assists proper interpretation and understanding of the SDD structure and the lesions' impact on surrounding photoreceptors produced by AO-SLO and vice versa.
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Affiliation(s)
- Alexander Meadway
- Department of Ophthalmology, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, Al 35294, USA
| | - Xiaolin Wang
- Department of Ophthalmology, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, Al 35294, USA
| | - Christine A. Curcio
- Department of Ophthalmology, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, Al 35294, USA
| | - Yuhua Zhang
- Department of Ophthalmology, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, Al 35294, USA
- Department of Vision Sciences, University of Alabama at Birmingham, 1530 3rd Avenue South, Birmingham, AL 35294, USA
- Department of Biomedical Engineering, University of Alabama at Birmingham, 1825 University Boulevard, Birmingham, AL 35294, USA
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Rudolf M, Seckerdieck K, Grisanti S, Curcio CA. Internal structure consistent with remodelling in very small drusen, revealed by filipin histochemistry for esterified cholesterol. Br J Ophthalmol 2014; 98:698-702. [DOI: 10.1136/bjophthalmol-2013-304226] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Wang D, Zhou J, Hou X, Nguyen DH, Cao G, Li G, Qiu G, Zhang K, Zhang M, Su Z. CETP Gene may be Associated with Advanced Age-Related Macular Degeneration in the Chinese Population. Ophthalmic Genet 2014; 36:303-8. [PMID: 24498989 DOI: 10.3109/13816810.2014.881506] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVES This study aims to investigate whether variations in LIPC, CETP, ABCA1 and LPL, which are involved in high-density lipoprotein (HDL) metabolism, are associated with advanced age-related macular degeneration (AMD) in the Chinese population. DESIGN AND METHODS A total of 119 Chinese patients with advanced AMD and 99 control individuals were recruited. Genomic DNA was extracted from peripheral blood leukocytes. Genotypes of seven single nucleotide polymorphisms (SNPs) including rs1061170 and rs1410996 in CFH, rs10490924 in HTRA1, rs10468017 in LIPC, rs3764261 in CETP, rs1883025 in ABCA1 and rs12678919 near LPL were determined by polymerase chain reaction (PCR) followed by allele-specific restriction enzyme digestion or SNaPshot. Unconditional logistic regression analyses were performed to generate a risk predictive model. RESULTS We observed the frequency of allele A of rs3764261 in CETP to be significantly lower in advanced AMD after Bonferroni correction (15.5% in patients with AMD and 20.7% in controls; OR = 0.49, 95% CI: 0.29-0.85; p = 0.011). Furthermore, we found that it was also associated with reduced risk of both unilateral AMD (OR = 0.52, 95% CI: 0.28-0.98; p = 0.043) and bilateral AMD (OR = 0.45, 95% CI: 0.22-0.91; p = 0.026). Rs10468017 in LIPC, rs12678919 near LPL and rs1883025 in ABCA1 were not found to be associated with advanced AMD (all p > 0.05). CONCLUSION Our data suggested that the allele A in rs3764261 in CETP gene may be associated with a decreased risk of advanced AMD in Chinese population.
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Affiliation(s)
- Dan Wang
- a Molecular Medicine Research Center, State Key Laboratory of Biotherapy .,b Department of Ophthalmology , West China Hospital, Sichuan University , Chengdu , China , and
| | - Jie Zhou
- a Molecular Medicine Research Center, State Key Laboratory of Biotherapy .,b Department of Ophthalmology , West China Hospital, Sichuan University , Chengdu , China , and
| | - Xiaoming Hou
- a Molecular Medicine Research Center, State Key Laboratory of Biotherapy
| | - Duy H Nguyen
- c Department of Ophthalmology , University of California , San Diego , CA , USA
| | - Guiqun Cao
- a Molecular Medicine Research Center, State Key Laboratory of Biotherapy
| | - Gen Li
- a Molecular Medicine Research Center, State Key Laboratory of Biotherapy
| | - Guoxian Qiu
- b Department of Ophthalmology , West China Hospital, Sichuan University , Chengdu , China , and
| | - Kang Zhang
- a Molecular Medicine Research Center, State Key Laboratory of Biotherapy .,c Department of Ophthalmology , University of California , San Diego , CA , USA
| | - Ming Zhang
- b Department of Ophthalmology , West China Hospital, Sichuan University , Chengdu , China , and
| | - Zhiguang Su
- a Molecular Medicine Research Center, State Key Laboratory of Biotherapy
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Characteristics of fundus autofluorescence and drusen in the fellow eyes of Japanese patients with exudative age-related macular degeneration. Graefes Arch Clin Exp Ophthalmol 2013; 251:1-9. [PMID: 23677486 DOI: 10.1007/s00417-013-2363-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 03/22/2013] [Accepted: 04/22/2013] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND The main purpose of this study is to investigate the characteristics of fundus autofluorescence (FAF) and area of soft drusen among the fellow eyes of unilateral typical age-related macular degeneration (typical AMD) and polypoidal choroidal vasculopathy (PCV) in Japanese patients. METHODS FAF images were obtained from the fellow eyes of unilateral typical AMD (n = 64), unilateral PCV (n = 95), unilateral retinal angiomatous proliferation (RAP) (n = 4) and 56 control subjects, then classified into normal, minimal-change, and abnormal patterns by two graders. Interobserver variability between two graders and intraobserver variability were assessed for FAF classifications, and cases with inconsistent decisions were finally classified by the third grader. Soft drusen were segmented and their total areas were compared between the fellow eyes of typical AMD and PCV. Area(s) with increased autofluorescence were segmented to assess the relationship with soft drusen area(s). RESULTS Assessment for interobserver variability between two graders and intraobserver variability in one grader showed substantial agreement (κ = 0.70) and almost perfect agreement (κ = 0.85), respectively. In the final decision mediated by third grader, the proportions of eyes with either minimal-change FAF pattern or abnormal FAF pattern in the fellow eyes of both typical AMD (37 cases, 58 %) and PCV (47 cases, 49 %) were significantly higher than that of the control cases (15 cases, 27 %; p < 0.01). The proportion of abnormal FAF pattern in the fellow eyes of typical AMD (20 cases, 31 %) was higher than that of PCV (15 cases, 16 %; p < 0.05). Total soft drusen areas in the fellow eyes of typical AMD (0.369 ± 0.718 mm(2)) were larger than those of PCV (0.173 ± 0.408 mm(2); p < 0.05), and those in the eyes with abnormal FAF pattern were larger than those with minimal-change FAF pattern or normal FAF pattern (p < 0.01). Image analysis revealed a relationship between increased autofluorescence and soft drusen, especially in the cases with large total soft drusen areas. CONCLUSIONS FAF characteristics were different between the fellow eyes of unilateral typical AMD and PCV in Japan, which might be due to the difference of total soft drusen areas between them.
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van de Ven JP, Boon CJ, Smailhodzic D, Lechanteur YT, den Hollander AI, Hoyng CB, Theelen T. Short-term changes of Basal laminar drusen on spectral-domain optical coherence tomography. Am J Ophthalmol 2012; 154:560-7. [PMID: 22626619 DOI: 10.1016/j.ajo.2012.03.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 03/12/2012] [Accepted: 03/12/2012] [Indexed: 10/28/2022]
Abstract
PURPOSE To determine if small hard drusen in patients with basal laminar drusen show short-term changes. DESIGN Prospective observational case series. METHODS Ten subjects with basal laminar drusen were longitudinally followed during a period of 4 months by spectral-domain optical coherence tomography. Drusen that showed a spontaneous change in volume were further analyzed according to 5 morphologic parameters: shape, reflectivity, homogeneity, and concurring photoreceptor layer/retinal pigment epithelium damage. Odds ratios (OR) and risk for regression and progression of drusen volumes were calculated. RESULTS One hundred and five small hard drusen in 19 eyes showed a spontaneous change in volume over the period of follow-up. Drusen with a "pointed" shape were significantly associated (P = .031; OR 4.89; 95% confidence interval [CI] 1.16-20.67) with spontaneous progression in drusen volume, with a chance of 0.80 (95% CI 0.55-0.93) to progress. Drusen that showed a decreased reflectivity of overlying photoreceptor layer (P = .041; OR 7.67; 95% CI 1.09-54.24) or retinal pigment epithelium (P = .022; OR 12.38; 95% CI 1.44-106.57), showed a significant association with spontaneous regression in drusen volume, with chances of regression of 0.86 (95% CI 0.41-0.98) and 0.89 (95% CI 0.49-0.99), respectively. CONCLUSION Small hard drusen in patients with the basal laminar drusen phenotype are subject to a process of short-term remodeling. The dynamic nature of this disease points to high biochemical activity that may be sensitive to future pharmacologic treatment strategies. In addition, these short-term changes of drusen may be a source of misclassification in disease staging.
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Querques G, Guigui B, Leveziel N, Querques L, Bandello F, Souied EH. Multimodal morphological and functional characterization of Malattia Leventinese. Graefes Arch Clin Exp Ophthalmol 2012; 251:705-14. [PMID: 22814526 DOI: 10.1007/s00417-012-2106-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 06/22/2012] [Accepted: 06/30/2012] [Indexed: 11/28/2022] Open
Affiliation(s)
- Giuseppe Querques
- Department of Ophthalmology, University Paris Est Creteil, Centre Hospitalier Intercommunal de Creteil, 40 Avenue de Verdun, 94000 Creteil, France.
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Wang J, Ohno-Matsui K, Morita I. Cholesterol enhances amyloid β deposition in mouse retina by modulating the activities of Aβ-regulating enzymes in retinal pigment epithelial cells. Biochem Biophys Res Commun 2012; 424:704-9. [PMID: 22796523 DOI: 10.1016/j.bbrc.2012.07.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 07/06/2012] [Indexed: 10/28/2022]
Abstract
Subretinally-deposited amyloid β (Aβ) is a main contributor of developing age-related macular degeneration (AMD). However, the mechanism causing Aβ deposition in AMD eyes is unknown. Hypercholesterolemia is a significant risk for developing AMD. Thus, we investigated the effects of cholesterol on Aβ production in retinal pigment epithelial (RPE) cells in vitro and in the mouse retina in vivo. RPE cells isolated from senescent (12-month-old) C57BL/6 mice were treated with 10μg/ml cholesterol for 48h. Aβ amounts in culture supernatants were measured by ELISA. Activity and expression of enzymes and proteins that regulate Aβ production were examined by activity assay and real time PCR. The retina of mice fed cholesterol-enriched diet was examined by transmission electron microscopy. Cholesterol significantly increased Aβ production in cultured RPE cells. Activities of Aβ degradation enzyme; neprilysin (NEP) and anti-amyloidogenic secretase; α-secretase were significantly decreased in cell lysates of cholesterol-treated RPE cells compared to non-treated cells, but there was no change in the activities of β- or γ-secretase. mRNA levels of NEP and α-secretase (ADAM10 and ADAM17) were significantly lower in cholesterol-treated RPE cells than non-treated cells. Senescent (12-month-old) mice fed cholesterol-enriched chow developed subRPE deposits containing Aβ, whereas age-matched mice fed standard rodent chow diet did not. Activities and mRNA levels of NEP and α-secretase were significantly lower in native RPE cells freshly isolated from cholesterol-enriched chow fed mice compared to standard rodent chow fed mice. These findings suggest that cholesterol enhances subretinal Aβ accumulation by modulating the activities of enzymes degrading and processing Aβ in RPE cells in senescent subjects.
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Affiliation(s)
- Jiying Wang
- Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
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Gao S, Han X, Fu J, Yuan X, Sun X, Li Q. Influence of chronic stress on the compositions of hepatic cholesterol and triglyceride in male Wistar rats fed a high fat diet. Hepatol Res 2012; 42:686-95. [PMID: 22321167 DOI: 10.1111/j.1872-034x.2011.00961.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
AIM We determined the influence of chronic stress (CS) on the compositions of hepatic cholesterol and triglyceride (TG) in rats fed a high fat diet (HFD). METHODS Male Wistar rats were fed either a standard diet or a HFD and half of the HFD fed rats were given CS (electric foot shock assisted with noise) for 8 weeks. RESULTS Compared with the control group, the levels of hepatic total cholesterol (TC) and TG were significantly elevated in the HFD and HFD with chronic stress (HFD+CS) groups, and the more severe elevations of them were found in the HFD group. Inversely, the more severe elevations of hepatic water-soluble parts of TC and TG were found in the HFD+CS group, as the elevations of low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol in liver and serum, tumor necrosis factor-α, interleukin-1β and malondialdehyde in liver. Meanwhile, downregulated mRNA expressions of hepatic liver X receptor-α (LXR-α) and peroxisome proliferator-activated receptor-γ (PPAR-γ) were also more severe in the HFD+CS group. CONCLUSION CS can aggravate the high levels of water-soluble compositions of hepatic TC and TG induced by HFD as it aggravates hepatic inflammation and oxidative stress; in spite of that, however, it cannot further promote hepatic lipidosis. This is consistent with the downregulated mRNA expressions of LXR-α and PPAR-γ.
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Affiliation(s)
- Siyuan Gao
- Department of Physiology, China Pharmaceutical University, Nanjing, China
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Abstract
BACKGROUND Previous studies of age-related macular degeneration have not quantified the number of drusen that accumulate fluorescein. Histopathologic studies have demonstrated druse subregions with different degrees of hydrophobicity, and these subregions might potentially exhibit different degrees of fluorescein uptake. METHODS We evaluated macular drusen from 35 age-related macular degeneration patients by measuring druse area in color digital images and fluorescein angiograms, using 2 morphometric methods. RESULTS Of 828 drusen evaluated, 405 had a corresponding fluorescein angiogram signal. About half of all drusen per eye (49.57%) stained in each participant. Among fluorescein-stained drusen, druse size measured in color images did not differ significantly from the sizes measured in corresponding fluorescein images (P = 0.8105), across the range of druse sizes. CONCLUSION These findings indicate that our understanding of drusen subregion staining may not directly correlate to in vivo observations of macular drusen in age-related macular degeneration.
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Dasari B, Prasanthi JRP, Marwarha G, Singh BB, Ghribi O. Cholesterol-enriched diet causes age-related macular degeneration-like pathology in rabbit retina. BMC Ophthalmol 2011; 11:22. [PMID: 21851605 PMCID: PMC3170645 DOI: 10.1186/1471-2415-11-22] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2011] [Accepted: 08/18/2011] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Alzheimer's disease (AD) and age-related macular degeneration (AMD) share several pathological hallmarks including β-amyloid (Aβ) accumulation, oxidative stress, and apoptotic cell death. The causes of AD and AMD are likely multi-factorial with several factors such as diet, environment, and genetic susceptibility participating in the pathogenesis of these diseases. Epidemiological studies correlated high plasma cholesterol levels with high incidence of AD, and feeding rabbits with a diet rich in cholesterol has been shown to induce AD-like pathology in rabbit brain. High intake of cholesterol and saturated fat were also long been suspected to increase the risk for AMD. However, the extent to which cholesterol-enriched diet may also cause AMD-like features in rabbit retinas is not well known. METHODS Male New Zealand white rabbits were fed normal chow or a 2% cholesterol-enriched diet for 12 weeks. At necropsy, animals were perfused with Dulbecco's phosphate-buffered saline and the eyes were promptly removed. One eye of each animal was used for immunohistochemistry and retina dissected from the other eye was used for Western blot, ELISA assays, spectrophotometry and mass spectrometry analyses. RESULTS Increased levels of Aβ, decreased levels of the anti-apoptotic protein Bcl-2, increased levels of the pro-apoptotic Bax and gadd153 proteins, emergence of TUNEL-positive cells, and increased generation of reactive oxygen species were found in retinas from cholesterol-fed compared to normal chow-fed rabbits. Additionally, astrogliosis, drusen-like debris and cholesterol accumulations in retinas from cholesterol-fed rabbits were observed. As several lines of evidence suggest that oxidized cholesterol metabolites (oxysterols) may be the link by which cholesterol contributes to the pathogenesis of AMD, we determined levels of oxysterols and found a dramatic increase in levels of oxysterols in retinas from cholesterol-fed rabbits. CONCLUSIONS Our results suggest that cholesterol-enriched diets cause retinal degeneration that is relevant to AMD. Furthermore, our data suggests high cholesterol levels and subsequent increase in the cholesterol metabolites as potential culprits to AMD.
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Affiliation(s)
- Bhanu Dasari
- Department of Pharmacology, Physiology and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, 58202, USA
| | - Jaya RP Prasanthi
- Department of Pharmacology, Physiology and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, 58202, USA
| | - Gurdeep Marwarha
- Department of Pharmacology, Physiology and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, 58202, USA
| | - Brij B Singh
- Department of Biochemistry and Molecular Biology, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, 58202, USA
| | - Othman Ghribi
- Department of Pharmacology, Physiology and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, 58202, USA
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Yu Y, Reynolds R, Fagerness J, Rosner B, Daly MJ, Seddon JM. Association of variants in the LIPC and ABCA1 genes with intermediate and large drusen and advanced age-related macular degeneration. Invest Ophthalmol Vis Sci 2011; 52:4663-70. [PMID: 21447678 DOI: 10.1167/iovs.10-7070] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Intermediate and large drusen usually precede advanced age-related macular degeneration (AMD). There is little information about which genes influence drusen accumulation. Discovery of genetic variants associated with drusen may lead to prevention and treatments of AMD in its early stages. METHODS A total of 3066 subjects were evaluated on the basis of ocular examinations and fundus photography and categorized as control (n = 221), intermediate drusen (n = 814), large drusen (n = 949), or advanced AMD (n = 1082). SNPs in the previously identified CFH, C2, C3, CFB, CFI, APOE, and ARMS2/HTRA1 genes/regions and the novel genes LIPC, CETP, and ABCA1 in the high-density lipoprotein (HDL) cholesterol pathway were genotyped. Associations between stage of AMD and SNPs were assessed using logistic regression. RESULTS Controlling for age, sex, education, smoking, body mass index, and antioxidant treatment, the number of minor (T) alleles of the genes LIPC and ABCA1 were significantly associated with a reduced risk of intermediate drusen (LIPC [P trend = 0.045], ABCA1 [P = 4.4 × 10(-3)]), large drusen (LIPC [P = 0.041], ABCA1 [P = 7.7 × 10(-4)]), and advanced AMD (LIPC [P = 1.8 × 10(-3)], ABCA1 [P = 3 × 10(-4)]). After further adjustment for known genetic factors, the protective effect of the TT genotype was significant for intermediate drusen (LIPC [odds ratio (OR), 0.56; 95% confidence interval (CI), 0.33-0.94], ABCA1 [OR, 0.48; 95% CI, 0.27-0.85]), large drusen (LIPC [OR, 0.58; 95% CI, 0.34-0.98)], ABCA1 [OR, 0.41; 95% CI, 0.23-0.74)]), and advanced AMD (LIPC [OR, 0.39; 95% CI, 0.21-0.74)], ABCA1 [OR, 0.35; 95% CI, 0.17-0.71)]). CFH, C3, C2, and ARMS2/HTRA1 were associated with large drusen and advanced AMD. CONCLUSIONS LIPC and ABCA1 are related to intermediate and large drusen, as well as advanced AMD. CFH, C3, C2, and ARMS2/HTRA1 are associated with large drusen and advanced AMD. Genes may have varying effects on different stages of AMD.
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Affiliation(s)
- Yi Yu
- Ophthalmic Epidemiology and Genetics Service, Department of Ophthalmology, Tufts Medical Center, Boston, Massachusetts, USA
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Charvet C, Liao WL, Heo GY, Laird J, Salomon RG, Turko IV, Pikuleva IA. Isolevuglandins and mitochondrial enzymes in the retina: mass spectrometry detection of post-translational modification of sterol-metabolizing CYP27A1. J Biol Chem 2011; 286:20413-22. [PMID: 21498512 PMCID: PMC3121529 DOI: 10.1074/jbc.m111.232546] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 04/04/2011] [Indexed: 11/06/2022] Open
Abstract
We report the first peptide mapping and sequencing of an in vivo isolevuglandin-modified protein. Mitochondrial cytochrome P450 27A1 (CYP27A1) is a ubiquitous multifunctional sterol C27-hydroxylase that eliminates cholesterol and likely 7-ketocholesterol from the retina and many other tissues. We investigated the post-translational modification of this protein with isolevuglandins, arachidonate oxidation products. Treatment of purified recombinant CYP27A1 with authentic iso[4]levuglandin E(2) (iso[4]LGE(2)) in vitro diminished enzyme activity in a time- and phospholipid-dependent manner. A multiple reaction monitoring protocol was then developed to identify the sites and extent of iso[4]LGE(2) adduction. CYP27A1 exhibited only three Lys residues, Lys(134), Lys(358), and Lys(476), that readily interact with iso[4]LGE(2) in vitro. Such selective modification enabled the generation of an internal standard, (15)N-labeled CYP27A1 modified with iso[4]LGE(2), for the subsequent analysis of a human retinal sample. Two multiple reaction monitoring transitions arising from the peptide AVLK(358)(-C(20)H(26)O(3))ETLR in the retinal sample were observed that co-eluted with the corresponding two (15)N transitions from the supplemented standard. These data demonstrate that modified CYP27A1 is present in the retina. We suggest that such protein modification impairs sterol elimination and likely has other pathological sequelae. We also propose that the post-translational modifications identified in CYP27A1 exemplify a general mechanism whereby oxidative stress and inflammation deleteriously affect protein function, contributing, for example, to cholesterol-rich lesions associated with age-related macular degeneration and cardiovascular disease. The proteomic protocols developed in this study are generally applicable to characterization of lipid-derived oxidative protein modifications occurring in vivo, including proteins bound to membranes.
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Affiliation(s)
- Casey Charvet
- From the Departments of Ophthalmology and Visual Sciences and
| | - Wei-Li Liao
- the Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850, and
| | - Gun-Young Heo
- From the Departments of Ophthalmology and Visual Sciences and
| | - James Laird
- Chemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | | | - Illarion V. Turko
- the Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850, and
- the Analytical Chemistry Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899
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Picard E, Houssier M, Bujold K, Sapieha P, Lubell W, Dorfman A, Racine J, Hardy P, Febbraio M, Lachapelle P, Ong H, Sennlaub F, Chemtob S. CD36 plays an important role in the clearance of oxLDL and associated age-dependent sub-retinal deposits. Aging (Albany NY) 2011; 2:981-9. [PMID: 21098885 PMCID: PMC3034186 DOI: 10.18632/aging.100218] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Age-related macular degeneration (AMD) represents the major cause of vision loss in industrialized nations. Laminar deposits in Bruch's membrane (BM) are among the first prominent histopathologic features, along with drusen formation, and have been found to contain oxidized lipids. Increases in concentrations of oxidized LDL (oxLDL) in plasma are observed with age and high fat high (HFHC) cholesterol diet. CD36 is the principal receptor implicated in uptake of oxLDL, and is expressed in the retinal pigment epithelium (RPE). We determined if CD36 participates in oxLDL uptake in RPE and correspondingly in clearance of sub-retinal deposits. Uptake of oxLDL by RPE in vitro and in vivo was CD36-dependent. CD36 deficiency in mice resulted in age-associated accumulation of oxLDL and sub-retinal BM thickening, despite fed a regular diet. Conversely, treatment of HFHC-fed ApoE null mice with a CD36 agonist, EP80317 (300 μg/kg/day), markedly diminished thickening of BM, and partially preserved (in part) photoreceptor function. In conclusion, our data uncover a new role for CD36 in the clearance of oxidized lipids from BM and in the prevention of age-dependent sub-retinal laminar deposits.
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Affiliation(s)
- Emilie Picard
- Department of Pediatrics, Hospitals Ste. Justine and Maisonneuve-Rosemont, Université de Montréal, Montreal, Quebec, Canada
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Abstract
PURPOSE To characterize the known appearance of cuticular drusen, subretinal drusenoid deposits (reticular pseudodrusen), and soft drusen as revealed by multimodal fundus imaging and to create an explanatory model that accounts for these observations. METHODS Reported color, fluorescein angiographic, autofluorescence, and spectral domain optical coherence tomography images of patients with cuticular drusen, soft drusen, and subretinal drusenoid deposits were reviewed, as were actual images from affected eyes. Representative histological sections were examined. The geometry, location, and imaging characteristics of these lesions were evaluated. A hypothesis based on the Beer-Lambert law of light absorption was generated to fit these observations. RESULTS Cuticular drusen appear as numerous, uniform, round, yellow-white punctate accumulations under the retinal pigment epithelium (RPE). Soft drusen are larger, yellow-white dome-shaped mounds of deposit under the RPE. Subretinal drusenoid deposits are polymorphous light-gray interconnected accumulations above the RPE. Based on the model, both cuticular and soft drusen appear yellow because of the removal of shorter wavelength light by a double pass through the RPE. Subretinal drusenoid deposits, which are located on the RPE, are not subjected to short-wavelength attenuation and therefore are more prominent when viewed with blue light. The location and morphology of extracellular material in relationship to the RPE, and associated changes to RPE morphology and pigmentation, appeared to be the primary determinants of druse appearance in different imaging modalities. CONCLUSION Although cuticular drusen, subretinal drusenoid deposits, and soft drusen are composed of common components, they are distinguishable by multimodal imaging because of differences in location, morphology, and optical filtering effects by drusenoid material and the RPE.
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Fliesler SJ, Bretillon L. The ins and outs of cholesterol in the vertebrate retina. J Lipid Res 2010; 51:3399-413. [PMID: 20861164 DOI: 10.1194/jlr.r010538] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The vertebrate retina has multiple demands for utilization of cholesterol and must meet those demands either by synthesizing its own supply of cholesterol or by importing cholesterol from extraretinal sources, or both. Unlike the blood-brain barrier, the blood-retina barrier allows uptake of cholesterol from the circulation via a lipoprotein-based/receptor-mediated mechanism. Under normal conditions, cholesterol homeostasis is tightly regulated; also, cholesterol exists in the neural retina overwhelmingly in unesterified form, and sterol intermediates are present in minimal to negligible quantities. However, under certain pathological conditions, either due to an inborn error in cholesterol biosynthesis or as a consequence of exposure to selective inhibitors of enzymes in the cholesterol pathway, the ratio of sterol intermediates to cholesterol in the retina can rise dramatically and persist, in some cases resulting in progressive degeneration that significantly compromises the structure and function of the retina. Although the relative contributions of de novo synthesis versus extraretinal uptake are not yet known, herein we review what is known about these processes and the dynamics of cholesterol in the vertebrate retina and indicate some future avenues of research in this area.
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Affiliation(s)
- Steven J Fliesler
- Research Service, Veterans Administration Western New York Healthcare System, University at Buffalo, The State University of New York, Buffalo, NY, USA.
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Dasari B, Prasanthi JRP, Marwarha G, Singh BB, Ghribi O. The oxysterol 27-hydroxycholesterol increases β-amyloid and oxidative stress in retinal pigment epithelial cells. BMC Ophthalmol 2010; 10:22. [PMID: 20836858 PMCID: PMC2946278 DOI: 10.1186/1471-2415-10-22] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Accepted: 09/13/2010] [Indexed: 01/09/2023] Open
Abstract
Background Alzheimer's disease (AD) and age-related macular degeneration (AMD) share several pathological features including β-amyloid (Aβ) peptide accumulation, oxidative damage, and cell death. The causes of AD and AMD are not known but several studies suggest disturbances in cholesterol metabolism as a culprit of these diseases. We have recently shown that the cholesterol oxidation metabolite 27-hydroxycholesterol (27-OHC) causes AD-like pathology in human neuroblastoma SH-SY5Y cells and in organotypic hippocampal slices. However, the extent to which and the mechanisms by which 27-OHC may also cause pathological hallmarks related to AMD are ill-defined. In this study, the effects of 27-OHC on AMD-related pathology were determined in ARPE-19 cells. These cells have structural and functional properties relevant to retinal pigmented epithelial cells, a target in the course of AMD. Methods ARPE-19 cells were treated with 0, 10 or 25 μM 27-OHC for 24 hours. Levels of Aβ peptide, mitochondrial and endoplasmic reticulum (ER) stress markers, Ca2+ homeostasis, glutathione depletion, reactive oxygen species (ROS) generation, inflammation and cell death were assessed using ELISA, Western blot, immunocytochemistry, and specific assays. Results 27-OHC dose-dependently increased Aβ peptide production, increased levels of ER stress specific markers caspase 12 and gadd153 (also called CHOP), reduced mitochondrial membrane potential, triggered Ca2+ dyshomeostasis, increased levels of the nuclear factor κB (NFκB) and heme-oxygenase 1 (HO-1), two proteins activated by oxidative stress. Additionally, 27-OHC caused glutathione depletion, ROS generation, inflammation and apoptotic-mediated cell death. Conclusions The cholesterol metabolite 27-OHC is toxic to RPE cells. The deleterious effects of this oxysterol ranged from Aβ accumulation to oxidative cell damage. Our results suggest that high levels of 27-OHC may represent a common pathogenic factor for both AMD and AD.
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Affiliation(s)
- Bhanu Dasari
- Department of Pharmacology, University of North Dakota School of Medicine and Health Sciences, 501 North Columbia Road, Grand Forks, North Dakota 58202, USA.
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Wang L, Clark ME, Crossman DK, Kojima K, Messinger JD, Mobley JA, Curcio CA. Abundant lipid and protein components of drusen. PLoS One 2010; 5:e10329. [PMID: 20428236 PMCID: PMC2859054 DOI: 10.1371/journal.pone.0010329] [Citation(s) in RCA: 252] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2010] [Accepted: 03/30/2010] [Indexed: 01/24/2023] Open
Abstract
Background Drusen are extracellular lesions characteristic of aging and age-related maculopathy, a major retinal disease of the elderly. We determined the relative proportions of lipids and proteins in drusen capped with retinal pigment epithelium (RPE) and in RPE isolated from non-macular regions of 36 human retinas with grossly normal maculas obtained <6 hr after death. Methodology/Principal Findings Druse pellets were examined by light and electron microscopy. Component proteins were extracted using novel methods for preserved tissues, separated, subjected to tryptic digestion and LC-MS(MS)2 analysis using an ion trap mass spectrometer, and identified with reference to databases. Lipid classes were separated using thin layer chromatography and quantified by densitometry. Major druse components were esterified cholesterol (EC), phosphatidylcholine (PC), and protein (37.5±13.7, 36.9±12.9, and 43.0±11.5 ng/druse, respectively). Lipid-containing particles (median diameter, 77 nm) occupied 37–44% of druse volume. Major proteins include vitronectin, complement component 9, apoE, and clusterin, previously seen in drusen, and ATP synthase subunit β, scavenger receptor B2, and retinol dehydrogenase 5, previously seen in RPE. Drusen and RPE had similar protein profiles, with higher intensities and greater variability in drusen. C8, part of the complement membrane attack complex, was localized in drusen by immunofluorescence. Conclusions/Significance At least 40% of druse content is comprised by lipids dominated by EC and PC, 2 components that are potentially accounted for by just one pathway, the secretion of lipoproteins by RPE. Manipulating genes encoding apolipoprotein pathways would be a fruitful approach to producing drusen with high EC content in laboratory animals. Therapies that directly mitigate drusen should prepare for the substantial volume of neutral lipids. The catalog of major druse proteins is nearing completion.
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Affiliation(s)
- Lan Wang
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Mark E. Clark
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - David K. Crossman
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Kyoko Kojima
- Department of Epidemiology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Jeffrey D. Messinger
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - James A. Mobley
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Christine A. Curcio
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- * E-mail:
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Anderson DH, Radeke MJ, Gallo NB, Chapin EA, Johnson PT, Curletti CR, Hancox LS, Hu J, Ebright JN, Malek G, Hauser MA, Rickman CB, Bok D, Hageman GS, Johnson LV. The pivotal role of the complement system in aging and age-related macular degeneration: hypothesis re-visited. Prog Retin Eye Res 2009; 29:95-112. [PMID: 19961953 DOI: 10.1016/j.preteyeres.2009.11.003] [Citation(s) in RCA: 554] [Impact Index Per Article: 36.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
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.
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Affiliation(s)
- Don H Anderson
- Center for the Study of Macular Degeneration, Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA.
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Curcio CA, Johnson M, Huang JD, Rudolf M. Aging, age-related macular degeneration, and the response-to-retention of apolipoprotein B-containing lipoproteins. Prog Retin Eye Res 2009; 28:393-422. [PMID: 19698799 PMCID: PMC4319375 DOI: 10.1016/j.preteyeres.2009.08.001] [Citation(s) in RCA: 189] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The largest risk factor for age-related macular degeneration (ARMD) is advanced age. A prominent age-related change in the human retina is the accumulation of histochemically detectable neutral lipid in normal Bruch's membrane (BrM) throughout adulthood. This change has the potential to have a major impact on physiology of the retinal pigment epithelium (RPE). It occurs in the same compartment as drusen and basal linear deposit, the pathognomonic extracellular, lipid-containing lesions of ARMD. Here we present evidence from light microscopic histochemistry, ultrastructure, lipid profiling of tissues and isolated lipoproteins, and gene expression analysis that this deposition can be accounted for by esterified cholesterol-rich, apolipoprotein B-containing lipoprotein particles constitutively produced by the RPE. This work collectively allows ARMD lesion formation and its aftermath to be conceptualized as a response to the retention of a sub-endothelial apolipoprotein B lipoprotein, similar to a widely accepted model of atherosclerotic coronary artery disease (CAD) (Tabas et al., 2007). This approach provides a wide knowledge base and sophisticated clinical armamentarium that can be readily exploited for the development of new model systems and the future benefit of ARMD patients.
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Affiliation(s)
- Christine A Curcio
- Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, AL 35294-0009, USA.
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Curcio CA, Johnson M, Huang JD, Rudolf M. Apolipoprotein B-containing lipoproteins in retinal aging and age-related macular degeneration. J Lipid Res 2009; 51:451-67. [PMID: 19797256 DOI: 10.1194/jlr.r002238] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The largest risk factor for age-related macular degeneration (ARMD) is advanced age. With aging, there is a striking accumulation of neutral lipids in Bruch's membrane (BrM) of normal eye that continues through adulthood. This accumulation has the potential to significantly impact the physiology of the retinal pigment epithelium (RPE). It also ultimately leads to the creation of a lipid wall at the same locations where drusen and basal linear deposit, the pathognomonic extracellular, lipid-containing lesions of ARMD, subsequently form. Here, we summarize evidence obtained from light microscopy, ultrastructural studies, lipid histochemistry, assay of isolated lipoproteins, and gene expression analysis. These studies suggest that lipid deposition in BrM is at least partially due to accumulation of esterified cholesterol-rich, apolipoprotein B-containing lipoprotein particles produced by the RPE. Furthermore, we suggest that the formation of ARMD lesions and their aftermath may be a pathological response to the retention of a sub-endothelial apolipoprotein B lipoprotein, similar to a widely accepted model of atherosclerotic coronary artery disease (Tabas, I., K. J. Williams, and J. Borén. 2007. Subendothelial lipoprotein retention as the initiating process in atherosclerosis: update and therapeutic implications. Circulation. 116:1832-1844). This view provides a conceptual basis for the development of novel treatments that may benefit ARMD patients in the future.
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Affiliation(s)
- Christine A Curcio
- Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, AL, USA.
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Kochounian H, Johnson LV, Fong HKW. Accumulation of extracellular RGR-d in Bruch's membrane and close association with drusen at intercapillary regions. Exp Eye Res 2009; 88:1129-36. [PMID: 19450444 PMCID: PMC2763577 DOI: 10.1016/j.exer.2009.01.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Revised: 01/29/2009] [Accepted: 01/30/2009] [Indexed: 10/21/2022]
Abstract
Human retinal pigment epithelial (RPE) cells synthesize an extraneous splice isoform of retinal G protein-coupled receptor (RGR). In this study, we analyzed the exon-skipping variant of RGR (RGR-d) that is found in extracellular deposits. RPE-choroid tissue sections were prepared from postmortem human eyes from donors of various ages. RGR-d was analyzed in drusen and Bruch's membrane by immunohistochemical localization. Extracellular RGR-d is present in most drusen, including hard, soft, confluent and early-stage. Initial drusen formation is known to be preferentially associated with the intercapillary regions of Bruch's membrane. We corroborated this significant association of drusen, including early-stage drusen, with the intercapillary regions. The distribution of extracellular RGR-d in Bruch's membrane differs in old and young donors. In older persons, nodes of concentrated RGR-d accumulate at intercapillary loci, predominantly at the lateral edges of the capillaries of the choriocapillaris. RGR-d loci at the lateral capillary wall appear numerous in old, but not young, donors. Intensely immunostained RGR-d loci can be found at the base of early-stage drusen mounds in the older donors and may precede the formation of these drusen.
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Affiliation(s)
- Harold Kochounian
- Department of Molecular Microbiology and Immunology, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90033
| | - Lincoln V. Johnson
- Center for the Study of Macular Degeneration, Neuroscience Research Institute, University of California, Santa Barbara, CA 93106
| | - Henry K. W. Fong
- Department of Molecular Microbiology and Immunology, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90033
- Doheny Eye Institute, Los Angeles, CA 90033
- Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90033
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Wang L, Li CM, Rudolf M, Belyaeva OV, Chung BH, Messinger JD, Kedishvili NY, Curcio CA. Lipoprotein particles of intraocular origin in human Bruch membrane: an unusual lipid profile. Invest Ophthalmol Vis Sci 2008; 50:870-7. [PMID: 18806290 DOI: 10.1167/iovs.08-2376] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Throughout adulthood, Bruch membrane (BrM) accumulates esterified cholesterol (EC) associated with abundant 60- to 80-nm-diameter lipoprotein-like particles (LLP), putative apolipoprotein B (apoB) lipoproteins secreted by the retinal pigment epithelium (RPE). In the present study, neutral lipid, phospholipids, and retinoid components of human BrM-LLP were assayed. METHODS Particles isolated from paired choroids of human donors were subjected to comprehensive lipid profiling (preparative liquid chromatography [LC] gas chromatography [GC]), thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), Western blot analysis, and negative stain electron microscopy. Results were compared to plasma lipoproteins isolated from normolipemic volunteers and to conditioned medium from RPE-J cells supplemented with palmitate to induce particle synthesis and secretion. RESULTS EC was the largest component (32.4+/-7.9 mol%) of BrM-LLP lipids. EC was 11.3-fold more abundant than triglyceride (TG), unlike large apoB lipoproteins in plasma. Of the fatty acids (FA) esterified to cholesterol, linoleate (18:2n6) was the most abundant (41.7+/-4.7 mol%). Retinyl ester (RE) was detectable at picomolar levels in BrM-LLP. Notably scarce in any BrM-LLP lipid class was the photoreceptor-abundant FA docosahexaenoate (DHA, 22:6n3). RPE-J cells synthesized apoB and numerous EC-rich spherical particles. CONCLUSIONS BrM-LLP composition resembles plasma LDL more than it does photoreceptors. An EC-rich core is possible for newly synthesized lipoproteins as well as those processed in plasma. Abundant EC could contribute to a transport barrier in aging and lesion formation in age-related maculopathy (ARM). Analysis of BrM-LLP composition has revealed new aspects of retinal cholesterol and retinoid homeostasis.
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Affiliation(s)
- Lan Wang
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama 35294-0009, USA
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Rudolf M, Malek G, Messinger JD, Clark ME, Wang L, Curcio CA. Sub-retinal drusenoid deposits in human retina: organization and composition. Exp Eye Res 2008; 87:402-8. [PMID: 18721807 DOI: 10.1016/j.exer.2008.07.010] [Citation(s) in RCA: 151] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Revised: 06/16/2008] [Accepted: 07/03/2008] [Indexed: 11/27/2022]
Abstract
We demonstrate histologically sub-retinal drusenoid debris in three aged human eyes, two of them affected by age-related maculopathy. By postmortem fundus examination, the lesions were drusen-like, i.e., they were pale spots apparently at the level of the retinal pigment epithelium (RPE). Light and electron microscopy revealed aggregations of membranous debris, the principal constituent of soft drusen, in the sub-retinal space. Immunohistochemistry and confocal microscopy confirmed the presence of molecules typically associated with drusen (positive for unesterified cholesterol, apoE, complement factor H, and vitronectin) without evidence for molecules associated with photoreceptors (lectin-binding disaccharide bridges and opsins), Müller cells (glial fibrillary acid protein and cellular retinal binding protein, CRALPB), or RPE (CRALPB). The fact that a drusenoid material, sharing some markers with conventional drusen, can occur on opposite faces of the RPE, suggests deranged polarity of normally highly vectorial processes for basolateral secretion from RPE, and that overproduction of secreted materials and direction of secretion are independently specified processes. In the future, drusenoid sub-retinal debris might be more frequently revealed by emerging high-resolution imaging techniques.
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Affiliation(s)
- Martin Rudolf
- Department of Ophthalmology, Callahan Eye Foundation Hospital, University of Alabama School of Medicine, Birmingham, AL 35294-0009, USA
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Rudolf M, Clark ME, Chimento MF, Li CM, Medeiros NE, Curcio CA. Prevalence and morphology of druse types in the macula and periphery of eyes with age-related maculopathy. Invest Ophthalmol Vis Sci 2008; 49:1200-9. [PMID: 18326750 DOI: 10.1167/iovs.07-1466] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Macular drusen are hallmarks of age-related maculopathy (ARM), but these focal extracellular lesions also appear with age in the peripheral retina. The present study was conducted to determine regional differences in morphology that contribute to the higher vulnerability of the macula to advanced disease. METHODS Drusen from the macula (n = 133) and periphery (n = 282) were isolated and concentrated from nine ARM-affected eyes. A semiquantitative light microscopic evaluation of 1-mum-thick sections included 12 parameters. RESULTS Significant differences were found between the macula and periphery in ease of isolation, distribution of druse type, composition qualities, and substructures. On harvesting, macular drusen were friable, with liquefied or crystallized contents. Peripheral drusen were resilient and never crystallized. On examination, soft drusen appeared in the macula only, had homogeneous content without significant substructures, and had abundant basal laminar deposits (BlamD). Several substructures, previously postulated as signatures of druse biogenesis, were found primarily in hard drusen. Specific to hard drusen, which appeared everywhere, were central subregions and reduced RPE coverage. Macular hard drusen with a rich substructure profile differed from primarily homogeneous peripheral hard drusen. Compound drusen, found in the periphery only, exhibited a composition profile that was not intermediate between hard and soft. CONCLUSIONS The data confirm regional differences in druse morphology, composition, and physical properties, most likely based on different formative mechanisms that may contribute to macular susceptibility for ARM progression. Two other reasons that only the macula is at high risk despite having relatively few drusen are the exclusive presence of soft drusen and the abundant BlamD in this region.
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Affiliation(s)
- Martin Rudolf
- Department of Ophthalmology, University of Alabama at Birmingham, Callahan Eye Foundation Hospital, Birmingham, Alabama 35294-0009, USA.
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