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Curcio CA, Kar D, Owsley C, Sloan KR, Ach T. Age-Related Macular Degeneration, a Mathematically Tractable Disease. Invest Ophthalmol Vis Sci 2024; 65:4. [PMID: 38466281 PMCID: PMC10916886 DOI: 10.1167/iovs.65.3.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 02/19/2024] [Indexed: 03/12/2024] Open
Abstract
A progression sequence for age-related macular degeneration onset may be determinable with consensus neuroanatomical nomenclature augmented by drusen biology and eye-tracked clinical imaging. This narrative review proposes to supplement the Early Treatment of Diabetic Retinopathy Study (sETDRS) grid with a ring to capture high rod densities. Published photoreceptor and retinal pigment epithelium (RPE) densities in flat mounted aged-normal donor eyes were recomputed for sETDRS rings including near-periphery rich in rods and cumulatively for circular fovea-centered regions. Literature was reviewed for tissue-level studies of aging outer retina, population-level epidemiology studies regionally assessing risk, vision studies regionally assessing rod-mediated dark adaptation (RMDA), and impact of atrophy on photopic visual acuity. The 3 mm-diameter xanthophyll-rich macula lutea is rod-dominant and loses rods in aging whereas cone and RPE numbers are relatively stable. Across layers, the largest aging effects are accumulation of lipids prominent in drusen, loss of choriocapillary coverage of Bruch's membrane, and loss of rods. Epidemiology shows maximal risk for drusen-related progression in the central subfield with only one third of this risk level in the inner ring. RMDA studies report greatest slowing at the perimeter of this high-risk area. Vision declines precipitously when the cone-rich central subfield is invaded by geographic atrophy. Lifelong sustenance of foveal cone vision within the macula lutea leads to vulnerability in late adulthood that especially impacts rods at its perimeter. Adherence to an sETDRS grid and outer retinal cell populations within it will help dissect mechanisms, prioritize research, and assist in selecting patients for emerging treatments.
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Affiliation(s)
- Christine A. Curcio
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, Alabama, United States
| | - Deepayan Kar
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, Alabama, United States
| | - Cynthia Owsley
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, Alabama, United States
| | - Kenneth R. Sloan
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, Alabama, United States
| | - Thomas Ach
- Department of Ophthalmology, University Hospital Bonn, Bonn, Germany
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2
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El-Darzi N, Mast N, Li Y, Pikuleva IA. APOB100 transgenic mice exemplify how the systemic circulation content may affect the retina without altering retinal cholesterol input. Cell Mol Life Sci 2024; 81:52. [PMID: 38253888 PMCID: PMC10803575 DOI: 10.1007/s00018-023-05056-4] [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: 09/08/2023] [Revised: 10/24/2023] [Accepted: 11/17/2023] [Indexed: 01/24/2024]
Abstract
Apolipoprotein B (APOB) is a constituent of unique lipoprotein particles (LPPs) produced in the retinal pigment epithelium (RPE), which separates the neural retina from Bruch's membrane (BrM) and choroidal circulation. These LPPs accumulate with age in BrM and contribute to the development of age-related macular degeneration, a major blinding disease. The APOB100 transgenic expression in mice, which unlike humans lack the full-length APOB100, leads to lipid deposits in BrM. Herein, we further characterized APOB100 transgenic mice. We imaged mouse retina in vivo and assessed chorioretinal lipid distribution, retinal sterol levels, retinal cholesterol input, and serum content as well as tracked indocyanine green-bound LPPs in mouse plasma and retina after an intraperitoneal injection. Retinal function and differentially expressed proteins were also investigated. APOB100 transgenic mice had increased serum LDL content and an additional higher density HDL subpopulation; their retinal cholesterol levels (initially decreased) became normal with age. The LPP cycling between the RPE and choroidal circulation was increased. Yet, LPP trafficking from the RPE to the neural retina was limited, and total retinal cholesterol input did not change. There were lipid deposits in the RPE and BrM, and retinal function was impaired. Retinal proteomics provided mechanistic insights. Collectively, our data suggested that the serum LDL/HDL ratio may not affect retinal pathways of cholesterol input as serum LPP load is mainly handled by the RPE, which offloads LPP excess to the choroidal circulation rather than neural retina. Different HDL subpopulations should be considered in studies linking serum LPPs and age-related macular degeneration.
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Affiliation(s)
- Nicole El-Darzi
- Department of Ophthalmology and Visual Science, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Natalia Mast
- Department of Ophthalmology and Visual Science, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Yong Li
- Department of Ophthalmology and Visual Science, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Irina A Pikuleva
- Department of Ophthalmology and Visual Science, Case Western Reserve University, Cleveland, OH, 44106, USA.
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Chakrabarty K, Nayak D, Debnath J, Das D, Shetty R, Ghosh A. Retinal organoids in disease modeling and drug discovery: Opportunities and challenges. Surv Ophthalmol 2023:S0039-6257(23)00127-3. [PMID: 37778668 DOI: 10.1016/j.survophthal.2023.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 09/25/2023] [Accepted: 09/25/2023] [Indexed: 10/03/2023]
Abstract
Diseases leading to retinal cell loss can cause severe visual impairment and blindness. The lack of effective therapies to address retinal cell loss and the absence of intrinsic regeneration in the human retina leads to an irreversible pathological condition. Progress in recent years in the generation of human three-dimensional retinal organoids from pluripotent stem cells makes it possible to recreate the cytoarchitecture and associated cell-cell interactions of the human retina in remarkable detail. These human three-dimensional retinal organoid systems made of distinct retinal cell types and possessing contextual physiological responses allow the study of human retina development and retinal disease pathology in a way animal model and two-dimensional cell cultures were unable to achieve. We describe the derivation of retinal organoids from human pluripotent stem cells and their application for modeling retinal disease pathologies, while outlining the opportunities and challenges for its application in academia and industry.
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Affiliation(s)
- Koushik Chakrabarty
- GROW Research Laboratory, Narayana Nethralaya Foundation, Bangalore, Karnataka, India.
| | - Divyani Nayak
- GROW Research Laboratory, Narayana Nethralaya Foundation, Bangalore, Karnataka, India
| | - Jayasree Debnath
- GROW Research Laboratory, Narayana Nethralaya Foundation, Bangalore, Karnataka, India
| | - Debashish Das
- Stem Cell Research Lab, GROW Lab, Narayana Nethralaya Foundation, Narayana Nethralaya, Bangalore, Karnataka, India
| | - Rohit Shetty
- Department of Cornea and Refractive Surgery, Narayana Nethralaya Eye Hospital, Bangalore, Karnataka, India
| | - Arkasubhra Ghosh
- GROW Research Laboratory, Narayana Nethralaya Foundation, Bangalore, Karnataka, India
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4
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Sterling JK, Baumann B, Foshe S, Voigt A, Guttha S, Alnemri A, McCright SJ, Li M, Zauhar RJ, Montezuma SR, Kapphahn RJ, Chavali VRM, Hill DA, Ferrington DA, Stambolian D, Mullins RF, Merrick D, Dunaief JL. Inflammatory adipose activates a nutritional immunity pathway leading to retinal dysfunction. Cell Rep 2022; 39:110942. [PMID: 35705048 PMCID: PMC9248858 DOI: 10.1016/j.celrep.2022.110942] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Revised: 01/24/2022] [Accepted: 05/20/2022] [Indexed: 11/21/2022] Open
Abstract
Age-related macular degeneration (AMD), the leading cause of irreversible blindness among Americans over 50, is characterized by dysfunction and death of retinal pigment epithelial (RPE) cells. The RPE accumulates iron in AMD, and iron overload triggers RPE cell death in vitro and in vivo. However, the mechanism of RPE iron accumulation in AMD is unknown. We show that high-fat-diet-induced obesity, a risk factor for AMD, drives systemic and local inflammatory circuits upregulating interleukin-1β (IL-1β). IL-1β upregulates RPE iron importers and downregulates iron exporters, causing iron accumulation, oxidative stress, and dysfunction. We term this maladaptive, chronic activation of a nutritional immunity pathway the cellular iron sequestration response (CISR). RNA sequencing (RNA-seq) analysis of choroid and retina from human donors revealed that hallmarks of this pathway are present in AMD microglia and macrophages. Together, these data suggest that inflamed adipose tissue, through the CISR, can lead to RPE pathology in AMD.
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Affiliation(s)
- Jacob K Sterling
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Medical Scientist Training Program, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Bailey Baumann
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Medical Scientist Training Program, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Sierra Foshe
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Andrew Voigt
- Institute for Vision Research, The University of Iowa, Iowa City, IA 52242, USA; Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Samyuktha Guttha
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Ahab Alnemri
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Sam J McCright
- Medical Scientist Training Program, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Division of Allergy and Immunology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Mingyao Li
- Department of Biostatistics, Epidemiology and Informatics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Randy J Zauhar
- Department of Chemistry & Biochemistry, University of the Sciences, Philadelphia, PA 19104, USA
| | - Sandra R Montezuma
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Rebecca J Kapphahn
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Venkata R M Chavali
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - David A Hill
- Division of Allergy and Immunology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Institute of Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Deborah A Ferrington
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Dwight Stambolian
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Robert F Mullins
- Institute for Vision Research, The University of Iowa, Iowa City, IA 52242, USA; Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - David Merrick
- Department of Medicine, Division of Endocrinology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Institute of Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Joshua L Dunaief
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
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Kim SY, Qian H. Comparison between sodium iodate and lipid peroxide murine models of age-related macular degeneration for drug evaluation-a narrative review. ANNALS OF EYE SCIENCE 2022; 7:8. [PMID: 37622161 PMCID: PMC10448775 DOI: 10.21037/aes-21-25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
Objective In this review, non-transgenic models of age-related macular degeneration (AMD) are discussed, with focuses on murine retinal degeneration induced by sodium iodate and lipid peroxide (HpODE) as preclinical study platforms. Background AMD is the most common cause of vision loss in a world with an increasingly aging population. The major phenotypes of early and intermediate AMD are increased drusen and autofluorescence, Müller glia activation, infiltrated subretinal microglia and inward moving retinal pigment epithelium cells. Intermediate AMD may progress to advanced AMD, characterized by geography atrophy and/or choroidal neovascularization. Various transgenic and non-transgenic animal models related to retinal degeneration have been generated to investigate AMD pathogenesis and pathobiology, and have been widely used as potential therapeutic evaluation platforms. Methods Two retinal degeneration murine models induced by sodium iodate and HpODE are described. Distinct pathological features and procedures of these two models are compared. In addition, practical protocol and material preparation and assessment methods are elaborated. Conclusion Retina degeneration induced by sodium iodate and HpODE in mouse eye resembles many clinical aspects of human AMD and complimentary to the existent other animal models. However, standardization of procedure and assessment protocols is needed for preclinical studies. Further studies of HpODE on different routes, doses and species will be valuable for the future extensive use. Despite many merits of murine studies, differences between murine and human should be always considered.
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Affiliation(s)
- Soo-Young Kim
- Department of Pharmaceutics, Department of Biology, Virginia Commonwealth University, Richmond, VA, 23298, USA
- Center for Nanomedicine, Wilmer Eye Institute, Department of Ophthalmology, Johns Hopkins University of Medicine, Baltimore, MD, 21287, USA
| | - Haohua Qian
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
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Allingham MJ, Mettu PS, Cousins SW. Phase 1 Clinical Trial of Elamipretide in Intermediate Age-Related Macular Degeneration and High-Risk Drusen. OPHTHALMOLOGY SCIENCE 2022; 2:100095. [PMID: 36246187 PMCID: PMC9560633 DOI: 10.1016/j.xops.2021.100095] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 10/29/2021] [Accepted: 12/06/2021] [Indexed: 11/25/2022]
Abstract
Purpose To assess safety, tolerability, and feasibility of subcutaneous administration of the mitochondrial-targeted drug elamipretide in patients with intermediate age-related macular degeneration (AMD) and high-risk drusen (HRD) and to perform exploratory analyses of change in visual function. Design Phase 1, single-center, open-label, 24-week clinical trial with preplanned HRD cohort. Participants Adult patients ≥55 years of age with intermediate AMD and HRD. Methods Participants received subcutaneous elamipretide 40 mg daily, with safety and tolerability assessed throughout the study. Ocular assessments included normal-luminance best-corrected visual acuity (BCVA), low-luminance best-corrected visual acuity (LLVA), normal-luminance binocular reading acuity (NLRA), low-luminance binocular reading acuity (LLRA), spectral-domain OCT, fundus autofluorescence (FAF), mesopic microperimetry, dark adaptation, and low-luminance questionnaire (LLQ). Main Outcome Measures The primary end point was safety and tolerability. Prespecified exploratory end points included changes from baseline in BCVA, LLVA, NLRA, LLRA, retinal pigment epithelium (RPE)-drusen complex (DC) volume by OCT, FAF, mesopic microperimetry, dark adaptation, and LLQ results. Results Subcutaneous administration of elamipretide was highly feasible. All participants with HRD (n = 21) experienced 1 or more adverse events (AEs), but all were mild (57%) or moderate (43%), with the most common events related to injection site reactions. No serious systemic AEs occurred. One participant discontinued because of injection site reaction, 1 participant withdrew because they did not wish to continue study visits, and 1 participant withdrew after experiencing transient visual impairment. Among the 18 participants who completed the study, mean change in BCVA from baseline to 24 weeks was +3.6 letters (P = 0.014) and LLVA was +5.6 letters (P = 0.004). Compared with baseline, mean NLRA improved by –0.11 logarithm of the minimum angle of resolution (logMAR) units (P = 0.001), and LLRA by −0.28 logMAR units (P < 0.0001). Significant improvements were found in 6 of 7 subscales of the LLQ (P<0.0015). No significant changes were observed for RPE-DC volume, FAF, mesopic microperimetry, or dark adaptation. Conclusions Elamipretide appeared to be generally safe and well tolerated in treating intermediate AMD and HRD. Exploratory analyses demonstrate a positive effect on visual function, particularly under low-luminance conditions. Further study of elamipretide for treatment of intermediate AMD with HRD is warranted.
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7
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Yuan TH, Yue ZS, Zhang GH, Wang L, Dou GR. Beyond the Liver: Liver-Eye Communication in Clinical and Experimental Aspects. Front Mol Biosci 2022; 8:823277. [PMID: 35004861 PMCID: PMC8740136 DOI: 10.3389/fmolb.2021.823277] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Accepted: 12/09/2021] [Indexed: 12/04/2022] Open
Abstract
The communication between organs participates in the regulation of body homeostasis under physiological conditions and the progression and adaptation of diseases under pathological conditions. The communication between the liver and the eyes has been received more and more attention. In this review, we summarized some molecular mediators that can reflect the relationship between the liver and the eye, and then extended the metabolic relationship between the liver and the eye. We also summarized some typical diseases and phenotypes that have been able to reflect the liver-eye connection in the clinic, especially non-alcoholic fatty liver disease (NAFLD) and diabetic retinopathy (DR). The close connection between the liver and the eye is reflected through multiple pathways such as metabolism, oxidative stress, and inflammation. In addition, we presented the connection between the liver and the eye in traditional Chinese medicine, and introduced the fact that artificial intelligence may use the close connection between the liver and the eye to help us solve some practical clinical problems. Paying attention to liver-eye communication will help us have a deeper and more comprehensive understanding of certain communication between liver diseases and eyes, and provide new ideas for their potential therapeutic strategy.
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Affiliation(s)
- Tian-Hao Yuan
- Department of Ophthalmology, Eye Institute of Chinese PLA, Xijing Hospital, Fourth Military Medical University, Xi'an, China.,Department of The Cadet Team 6 of School of Basic Medicine, Fourth Military Medical University, Xi'an, China
| | - Zhen-Sheng Yue
- Department of Ophthalmology, Eye Institute of Chinese PLA, Xijing Hospital, Fourth Military Medical University, Xi'an, China.,Department of Hepatobiliary Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Guo-Heng Zhang
- Department of Ophthalmology, Eye Institute of Chinese PLA, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Lin Wang
- Department of Hepatobiliary Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Guo-Rui Dou
- Department of Ophthalmology, Eye Institute of Chinese PLA, Xijing Hospital, Fourth Military Medical University, Xi'an, China
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Yu Y, Li L, Lin S, Hu J. Update of application of olfactory ensheathing cells and stem cells/exosomes in the treatment of retinal disorders. Stem Cell Res Ther 2022; 13:11. [PMID: 35012635 PMCID: PMC8751324 DOI: 10.1186/s13287-021-02685-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Accepted: 12/07/2021] [Indexed: 11/10/2022] Open
Abstract
Age-related macular degeneration, diabetic retinopathy, retinitis pigmentosa and other retinal disorders are the main causes of visual impairment worldwide. In the past, these retinal diseases, especially dry age-related macular degeneration, proliferative diabetic retinopathy and retinitis pigmentosa, were treated with traditional surgery and drugs. However, the effect was moderate. In recent years, researchers have used embryonic stem cells, induced pluripotent stem cells, mesenchymal stem cells, olfactory ensheathing cells and other stem cells to conduct experiments and found that stem cells can inhibit inflammation, regulate immune response, secrete neurotrophic factors, and differentiate into retinal cells to replace and promote restoration of the damaged parts. These stem cells have the potential to treat retinal diseases. Whether it is in animal experiments or clinical trials, the increase in the number of retinal cells, maintenance of function and improvement of visual function all reflect the advanced of stem cells to treat retinal diseases, but its risk preserves the donor's hidden pathogenic genes, immune rejection and tumorigenicity. With the development of exosomes study, researchers have discovered that exosomes come from a wide range of sources and can be secreted by almost all types of cells. Using exosomes with stem cell to treat retinal diseases is more effective than using stem cells alone. This review article summarizes the recent advances in the application of olfactory ensheathing cells and stem cells/exosomes in the treatment of retinal disorders.
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Affiliation(s)
- Yang Yu
- Department of Ophthalmology, The Second Affiliated Hospital of Fujian Medical University, Engineering Research Center of Assistive Technology for Visual Impairment, Fujian Province University, Quanzhou, 362000, Fujian Province, China
| | - Licheng Li
- Department of Ophthalmology, The Second Affiliated Hospital of Fujian Medical University, Engineering Research Center of Assistive Technology for Visual Impairment, Fujian Province University, Quanzhou, 362000, Fujian Province, China
| | - Shu Lin
- Centre of Neurological and Metabolic Research, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, 362000, Fujian Province, China. .,Diabetes and Metabolism Division, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, Sydney, NSW, 2010, Australia.
| | - Jianmin Hu
- Department of Ophthalmology, The Second Affiliated Hospital of Fujian Medical University, Engineering Research Center of Assistive Technology for Visual Impairment, Fujian Province University, Quanzhou, 362000, Fujian Province, China. .,The School of Medical Technology and Engineering, Fujian Medical University, Fuzhou, 350004, Fujian Province, China.
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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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Abstract
Inherited retinal diseases (IRDs) are an important cause of blindness worldwide. Over 270 genes have been associated with IRD. Genetic testing can determine the cause of the clinical disease in the majority of patients. However, at least 25-50% of patients with clinical diagnosis of IRD remain unsolved even after whole genome sequencing. Animal models of IRD can be useful for expanding the set of established IRD genes, to gain biological understanding of the function of these genes in the retina, and to test advanced therapeutics prior to human clinical trials. In this chapter some small and large animal models of IRD are discussed including some of the advantages and limitations of each for various forms of retinopathy.
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11
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Abstract
PURPOSE OF REVIEW This review explores metabolic syndrome (MetS) as a risk factor that accelerates aging in retinal neurons and may contribute to the neurodegeneration seen in glaucomatous optic neuropathy (GON) and age-related macular degeneration (AMD). RECENT FINDINGS Both animal model experiments and epidemiologic studies suggest that metabolic stress may lead to aberrant regulation of a number of cellular pathways that ultimately lead to premature aging of the cell, including those of a neuronal lineage. SUMMARY GON and AMD are each leading causes of irreversible blindness worldwide. Aging is a significant risk factor in the specific retinal neuron loss that is seen with each condition. Though aging at a cellular level is difficult to define, there are many mechanistic modifiers of aging. Metabolic-related stresses induce inflammation, oxidative stress, mitochondrial dysfunction, endoplasmic reticulum stress, alterations to the unfolded protein response, defects in autophagy, alterations to the microbiome, and deposition of advanced glycation end products that can all hasten the aging process. Due to the number of variables related to metabolic health, defining criteria to enable the study of risk factors at a population level is challenging. MetS is a definable constellation of related metabolic risk factors that includes enlarged waist circumference, dyslipidemia, systemic hypertension, and hyperglycemia. MetS has been associated with both GON and AMD and may contribute to disease onset and/or progression in each disease.
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12
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Clarkson-Townsend DA, Douglass AJ, Singh A, Allen RS, Uwaifo IN, Pardue MT. Impacts of high fat diet on ocular outcomes in rodent models of visual disease. Exp Eye Res 2021; 204:108440. [PMID: 33444582 PMCID: PMC7946735 DOI: 10.1016/j.exer.2021.108440] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 12/23/2020] [Accepted: 01/05/2021] [Indexed: 02/08/2023]
Abstract
High fat diets (HFD) have been utilized in rodent models of visual disease for over 50 years to model the effects of lipids, metabolic dysfunction, and diet-induced obesity on vision and ocular health. HFD treatment can recapitulate the pathologies of some of the leading causes of blindness, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR) in rodent models of visual disease. However, there are many important factors to consider when using and interpreting these models. To synthesize our current understanding of the importance of lipid signaling, metabolism, and inflammation in HFD-driven visual disease processes, we systematically review the use of HFD in mouse and rat models of visual disease. The resulting literature is grouped into three clusters: models that solely focus on HFD treatment, models of diabetes that utilize both HFD and streptozotocin (STZ), and models of AMD that utilize both HFD and genetic models and/or other exposures. Our findings show that HFD profoundly affects vision, retinal function, many different ocular tissues, and multiple cell types through a variety of mechanisms. We delineate how HFD affects the cornea, lens, uvea, vitreous humor, retina, retinal pigmented epithelium (RPE), and Bruch's membrane (BM). Furthermore, we highlight how HFD impairs several retinal cell types, including glia (microglia), retinal ganglion cells, bipolar cells, photoreceptors, and vascular support cells (endothelial cells and pericytes). However, there are a number of gaps, limitations, and biases in the current literature. We highlight these gaps and discuss experimental design to help guide future studies. Very little is known about how HFD impacts the lens, ciliary bodies, and specific neuronal populations, such as rods, cones, bipolar cells, amacrine cells, and retinal ganglion cells. Additionally, sex bias is an important limitation in the current literature, with few HFD studies utilizing female rodents. Future studies should use ingredient-matched control diets (IMCD), include both sexes in experiments to evaluate sex-specific outcomes, conduct longitudinal metabolic and visual measurements, and capture acute outcomes. In conclusion, HFD is a systemic exposure with profound systemic effects, and rodent models are invaluable in understanding the impacts on visual and ocular disease.
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Affiliation(s)
- Danielle A Clarkson-Townsend
- Gangarosa Department of Environmental Health, Emory University, Atlanta, GA, USA; Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Decatur, GA, USA
| | - Amber J Douglass
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Decatur, GA, USA
| | - Anayesha Singh
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Decatur, GA, USA; Emory Center for Ethics, Emory University, Atlanta, GA, USA
| | - Rachael S Allen
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Decatur, GA, USA; Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Ivie N Uwaifo
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Decatur, GA, USA; Department of Neuroscience, Emory University, Atlanta, GA, USA
| | - Machelle T Pardue
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Decatur, GA, USA; Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA.
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13
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Rowan S, Jiang S, Chang ML, Volkin J, Cassalman C, Smith KM, Streeter MD, Spiegel DA, Moreira-Neto C, Rabbani N, Thornalley PJ, Smith DE, Waheed NK, Taylor A. A low glycemic diet protects disease-prone Nrf2-deficient mice against age-related macular degeneration. Free Radic Biol Med 2020; 150:75-86. [PMID: 32068111 PMCID: PMC7747150 DOI: 10.1016/j.freeradbiomed.2020.02.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 01/30/2020] [Accepted: 02/12/2020] [Indexed: 12/16/2022]
Abstract
Age-related macular degeneration (AMD) is a major blinding disease, affecting over 14% of the elderly. Risk for AMD is related to age, diet, environment, and genetics. Dietary modulation of AMD risk is a promising treatment modality, but requires appropriate animal models to demonstrate advantages of diet. Mice lacking the antioxidant transcription factor Nrf2 (Nfe2l2) develop age-related retinopathy relevant to human AMD. Here we evaluated the effect of consuming high glycemic (HG) or low glycemic (LG) diets until 18-months of age on development of features relevant to AMD in Nrf2-null mice. Nrf2-null mice that consumed HG diets developed atrophic AMD, characterized by photoreceptor degeneration, retinal pigment epithelium (RPE) atrophy and pigmentary abnormalities, basal laminar deposits, and loss of the choriocapillaris. In contrast, Nrf2-null-mice that consumed LG diets did not develop retinal disease phenotypes. Consumption of HG diets was associated with accumulation of advanced glycation end-products in the RPE and systemically, whereas consumption of the LG diet was associated with increased levels of anti-glycative and anti-oxidative detoxification machinery. Together our data indicate that the Nrf2-null HG mouse is a good model for atrophic AMD studies and that the LG diet can activate protective pathways to prevent AMD, even in a genetically predisposed animal.
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Affiliation(s)
- Sheldon Rowan
- Laboratory for Nutrition and Vision Research, JM-USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, 02111, USA; Friedman School of Nutrition and Science Policy, Tufts University, Boston, MA, 02111, USA; Department of Ophthalmology, Tufts University School of Medicine, Boston, MA, 02111, USA.
| | - Shuhong Jiang
- Laboratory for Nutrition and Vision Research, JM-USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, 02111, USA; Inner Mongolia Autonomous Region People's Hospital, Hohhot, Inner Mongolia, 010017, China
| | - Min-Lee Chang
- Laboratory for Nutrition and Vision Research, JM-USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, 02111, USA
| | - Jonathan Volkin
- Laboratory for Nutrition and Vision Research, JM-USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, 02111, USA
| | - Christa Cassalman
- Department of Pathology and Laboratory Medicine, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Kelsey M Smith
- Laboratory for Nutrition and Vision Research, JM-USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, 02111, USA; Friedman School of Nutrition and Science Policy, Tufts University, Boston, MA, 02111, USA
| | | | - David A Spiegel
- Department of Chemistry, Yale University, New Haven, CT, 06520, USA
| | - Carlos Moreira-Neto
- Department of Ophthalmology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Naila Rabbani
- Clinical Sciences Research Laboratories, Warwick Medical School, University of Warwick, University Hospital, Coventry, CV2 2DX, UK; Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, P.O. Box 2713, Doha, Qatar
| | - Paul J Thornalley
- Clinical Sciences Research Laboratories, Warwick Medical School, University of Warwick, University Hospital, Coventry, CV2 2DX, UK; Diabetes Research Center, Qatar Biomedical Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 34110, Doha, Qatar
| | - Donald E Smith
- Laboratory for Nutrition and Vision Research, JM-USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, 02111, USA
| | - Nadia K Waheed
- Department of Ophthalmology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Allen Taylor
- Laboratory for Nutrition and Vision Research, JM-USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, 02111, USA; Friedman School of Nutrition and Science Policy, Tufts University, Boston, MA, 02111, USA; Department of Ophthalmology, Tufts University School of Medicine, Boston, MA, 02111, USA.
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14
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Abokyi S, To CH, Lam TT, Tse DY. Central Role of Oxidative Stress in Age-Related Macular Degeneration: Evidence from a Review of the Molecular Mechanisms and Animal Models. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:7901270. [PMID: 32104539 PMCID: PMC7035553 DOI: 10.1155/2020/7901270] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 01/18/2020] [Indexed: 11/17/2022]
Abstract
Age-related macular degeneration (AMD) is a common cause of visual impairment in the elderly. There are very limited therapeutic options for AMD with the predominant therapies targeting vascular endothelial growth factor (VEGF) in the retina of patients afflicted with wet AMD. Hence, it is important to remind readers, especially those interested in AMD, about current studies that may help to develop novel therapies for other stages of AMD. This study, therefore, provides a comprehensive review of studies on human specimens as well as rodent models of the disease, to identify and analyze the molecular mechanisms behind AMD development and progression. The evaluation of this information highlights the central role that oxidative damage in the retina plays in contributing to major pathways, including inflammation and angiogenesis, found in the AMD phenotype. Following on the debate of oxidative stress as the earliest injury in the AMD pathogenesis, we demonstrated how the targeting of oxidative stress-associated pathways, such as autophagy and nuclear factor erythroid 2-related factor 2 (Nrf2) signaling, might be the futuristic direction to explore in the search of an effective treatment for AMD, as the dysregulation of these mechanisms is crucial to oxidative injury in the retina. In addition, animal models of AMD have been discussed in great detail, with their strengths and pitfalls included, to assist inform in the selection of suitable models for investigating any of the molecular mechanisms.
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Affiliation(s)
- Samuel Abokyi
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong
- Department of Optometry, University of Cape Coast, Ghana
| | - Chi-Ho To
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong
| | - Tim T. Lam
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong
| | - Dennis Y. Tse
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong
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15
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Roddy GW, Rosa RH, Viker KB, Holman BH, Hann CR, Krishnan A, Gores GJ, Bakri SJ, Fautsch MP. Diet Mimicking "Fast Food" Causes Structural Changes to the Retina Relevant to Age-Related Macular Degeneration. Curr Eye Res 2019; 45:726-732. [PMID: 31735070 DOI: 10.1080/02713683.2019.1694156] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Introduction: Metabolic syndrome is a disorder characterized by a constellation of findings including truncal obesity, elevated blood pressure, abnormal cholesterol levels, and high blood glucose. Recent evidence suggests that metabolic syndrome may be associated with increased risk of age-related macular degeneration (AMD) and other eye diseases. Recently, C57BL/6J wild-type mice fed with a "fast food" diet consisting of high fat, cholesterol, and fructose-supplemented water showed unique systemic pathology consistent with metabolic syndrome and nonalcoholic steatohepatitis. Additionally, these mice showed higher levels of fibrosis, inflammation, endoplasmic reticulum stress, and mitochondrial dysfunction compared to mice fed with only a high-fat diet alone. Since similar pathways are activated in AMD, we sought to determine whether mice fed a "fast food" diet exhibited retinal changes.Methods: 3-month-old wild-type mice were randomized to a standard chow (n = 11) or a "fast food" (n = 18) diet and fed for 9 months. At 1 year of age, tissues were collected and retinas were analyzed using transmission electron microscopy. Quantitative measures of Bruch's membrane thickness and retinal pigment epithelium (RPE) cell counts were performed.Results: "Fast food" fed mice showed ocular pathology relevant to various stages of AMD including basal laminar deposits, focal thickening of Bruch's membrane, and a significant loss of RPE cells.Discussion/conclusion: A wild-type mouse model of metabolic syndrome fed a "fast food" diet developed changes to the retina similar to some of the pathologic features seen in AMD. Further investigations into this and similar animal models as well as further epidemiological studies are needed to more clearly define the association between metabolic syndrome and AMD.
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Affiliation(s)
- Gavin W Roddy
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, USA
| | - Robert H Rosa
- Department of Ophthalmology, Baylor Scott & White Eye Institute, Temple, Texas, USA
| | - Kimberly B Viker
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, USA
| | - Bradley H Holman
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, USA
| | - Cheryl R Hann
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, USA
| | - Anuradha Krishnan
- Department of Gastroenterology, Mayo Clinic, Rochester, Minnesota, USA
| | - Gregory J Gores
- Department of Gastroenterology, Mayo Clinic, Rochester, Minnesota, USA
| | - Sophie J Bakri
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, USA
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16
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Handa JT, Bowes Rickman C, Dick AD, Gorin MB, Miller JW, Toth CA, Ueffing M, Zarbin M, Farrer LA. A systems biology approach towards understanding and treating non-neovascular age-related macular degeneration. Nat Commun 2019; 10:3347. [PMID: 31350409 PMCID: PMC6659646 DOI: 10.1038/s41467-019-11262-1] [Citation(s) in RCA: 169] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 07/03/2019] [Indexed: 12/20/2022] Open
Abstract
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.
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Affiliation(s)
- James T Handa
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, 21287, MD, USA.
| | - Cathy Bowes Rickman
- Department of Ophthalmology, Duke University Medical Center, Durham, 27708, NC, USA
| | - Andrew D Dick
- Translational Health Sciences (Ophthalmology), University of Bristol, Bristol, BS8 1TH, UK.,University College London, Institute of Ophthalmology and the National Institute for Health Research Biomedical Research Centre, Moorfields Eye Hospital and UCL-Institute of Ophthalmology, London, WC1E 6BT, UK
| | - Michael B Gorin
- Department of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, UCLA, Los Angeles, 90095, CA, USA.,Brain Research Institute, UCLA, Los Angeles, 90095, CA, USA
| | - Joan W Miller
- Retina Service, Massachusetts Eye and Ear, Harvard Ophthalmology AMD Center of Excellence, Department of Ophthalmology, Harvard Medical School, Boston, 02114, MA, USA
| | - Cynthia A Toth
- Department of Ophthalmology, Duke University Medical Center, Durham, 27708, NC, USA
| | - Marius Ueffing
- Department of Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, D-72076, Germany
| | - Marco Zarbin
- Institute of Ophthalmology and Visual Science, New Jersey Medical School, Rutgers University, Newark, 07103, NJ, USA
| | - Lindsay A Farrer
- Departments of Medicine (Biomedical Genetics), Neurology, Ophthalmology, Epidemiology, and Biostatistics, Boston University Schools of Medicine and Public Health, Boston, 02118, MA, USA.
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17
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Human complement factor H Y402H polymorphism causes an age-related macular degeneration phenotype and lipoprotein dysregulation in mice. Proc Natl Acad Sci U S A 2019; 116:3703-3711. [PMID: 30808757 PMCID: PMC6397537 DOI: 10.1073/pnas.1814014116] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
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.
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A Review of Pathogenic Drivers of Age-Related Macular Degeneration, Beyond Complement, with a Focus on Potential Endpoints for Testing Therapeutic Interventions in Preclinical Studies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1185:9-13. [PMID: 31884581 DOI: 10.1007/978-3-030-27378-1_2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Age-related macular degeneration (AMD) continues to be the leading cause of visual impairment for the elderly in developed countries. It is a complex, multifactorial, progressive disease with diverse molecular pathways regulating its pathogenesis. One of the cardinal features of the early clinical subtype of AMD is the accumulation of lipid- and protein-rich deposits within Bruch's membrane, called drusen, which can be visualized by fundus imaging. Currently, multiple in vitro and in vivo model systems exist, which can be used to help tease out mechanisms associated with different molecular pathways driving disease initiation and progression. Given the lack of treatments for patients suffering from the dry form of AMD, it is imperative to appreciate the different known morphological endpoints associated with the various pathogenic pathways, in order to derive further insights, for the ultimate purpose of disease modeling and development of effective therapeutic interventions.
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19
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Jun S, Datta S, Wang L, Pegany R, Cano M, Handa JT. The impact of lipids, lipid oxidation, and inflammation on AMD, and the potential role of miRNAs on lipid metabolism in the RPE. Exp Eye Res 2018; 181:346-355. [PMID: 30292489 DOI: 10.1016/j.exer.2018.09.023] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 08/31/2018] [Accepted: 09/30/2018] [Indexed: 12/17/2022]
Abstract
The accumulation of lipids within drusen, the epidemiologic link of a high fat diet, and the identification of polymorphisms in genes involved in lipid metabolism that are associated with disease risk, have prompted interest in the role of lipid abnormalities in AMD. Despite intensive investigation, our understanding of how lipid abnormalities contribute to AMD development remains unclear. Lipid metabolism is tightly regulated, and its dysregulation can trigger excess lipid accumulation within the RPE and Bruch's membrane. The high oxidative stress environment of the macula can promote lipid oxidation, impairing their original function as well as producing oxidation-specific epitopes (OSE), which unless neutralized, can induce unwanted inflammation that additionally contributes to AMD progression. Considering the multiple layers of lipid metabolism and inflammation, and the ability to simultaneously target multiple pathways, microRNA (miRNAs) have emerged as important regulators of many age-related diseases including atherosclerosis and Alzheimer's disease. These diseases have similar etiologic characteristics such as lipid-rich deposits, oxidative stress, and inflammation with AMD, which suggests that miRNAs might influence lipid metabolism in AMD. In this review, we discuss the contribution of lipids to AMD pathobiology and introduce how miRNAs might affect lipid metabolism during lesion development. Establishing how miRNAs contribute to lipid accumulation in AMD will help to define the role of lipids in AMD, and open new treatment avenues for this enigmatic disease.
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Affiliation(s)
- Sujung Jun
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD, 21287, United States
| | - Sayantan Datta
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD, 21287, United States
| | - Lei Wang
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD, 21287, United States
| | - Roma Pegany
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD, 21287, United States
| | - Marisol Cano
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD, 21287, United States
| | - James T Handa
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD, 21287, United States.
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20
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Malek G, Busik J, Grant MB, Choudhary M. Models of retinal diseases and their applicability in drug discovery. Expert Opin Drug Discov 2018; 13:359-377. [PMID: 29382242 DOI: 10.1080/17460441.2018.1430136] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
INTRODUCTION The impact of vision debilitating diseases is a global public health concern, which will continue until effective preventative and management protocols are developed. Two retinal diseases responsible for the majority of vision loss in the working age adults and elderly populations are diabetic retinopathy (DR) and age-related macular degeneration (AMD), respectively. Model systems, which recapitulate aspects of human pathology, are valid experimental modalities that have contributed to the identification of signaling pathways involved in disease development and consequently potential therapies. Areas covered: The pathology of DR and AMD, which serve as the basis for designing appropriate models of disease, is discussed. The authors also review in vitro and in vivo models of DR and AMD and evaluate the utility of these models in exploratory and pre-clinical studies. Expert opinion: The complex nature of non-Mendelian diseases such as DR and AMD has made identification of effective therapeutic treatments challenging. However, the authors believe that while in vivo models are often criticized for not being a 'perfect' recapitulation of disease, they have been valuable experimentally when used with consideration of the strengths and limitations of the experimental model selected and have a place in the drug discovery process.
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Affiliation(s)
- Goldis Malek
- a Department of Ophthalmology , Duke University School of Medicine , Durham , NC , USA.,b Department of Pathology , Duke University School of Medicine , Durham , NC , USA
| | - Julia Busik
- c Department of Physiology , Michigan State University , East Lansing , MI , USA
| | - Maria B Grant
- d Department of Ophthalmology , University of Alabama at Birmingham , Birmingham , Al , USA
| | - Mayur Choudhary
- a Department of Ophthalmology , Duke University School of Medicine , Durham , NC , USA
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21
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Bonilha VL, Bell BA, Rayborn ME, Samuels IS, King A, Hollyfield JG, Xie C, Cai H. Absence of DJ-1 causes age-related retinal abnormalities in association with increased oxidative stress. Free Radic Biol Med 2017; 104:226-237. [PMID: 28088625 PMCID: PMC5328840 DOI: 10.1016/j.freeradbiomed.2017.01.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 01/09/2017] [Accepted: 01/10/2017] [Indexed: 01/05/2023]
Abstract
Oxidative stress alters physiological function in most biological tissues and can lead to cell death. In the retina, oxidative stress initiates a cascade of events leading to focal loss of RPE and photoreceptors, which is thought to be a major contributing factor to geographic atrophy. Despite these implications, the molecular regulation of RPE oxidative stress under normal and pathological conditions remains largely unknown. A better understanding of the mechanisms involved in regulating RPE and photoreceptors oxidative stress response is greatly needed. To this end we evaluated photoreceptor and RPE changes in mice deficient in DJ-1, a protein that is thought to be important in protecting cells from oxidative stress. Young (3 months) and aged (18 months) DJ-1 knockout (DJ-1 KO) and age-matched wild-type mice were examined. In both group of aged mice, scanning laser ophthalmoscopy (SLO) showed the presence of a few autofluorescent foci. The 18 month-old DJ-1 KO retinas were also characterized by a noticeable increase in RPE fluorescence to wild-type. Optical coherence tomography (OCT) imaging demonstrated that all retinal layers were present in the eyes of both DJ-1 KO groups. ERG comparisons showed that older DJ-1 KO mice had reduced sensitivity under dark- and light-adapted conditions compared to age-matched control. Histologically, the RPE contained prominent vacuoles in young DJ-1 KO group with the appearance of enlarged irregularly shaped RPE cells in the older group. These were also evident in OCT and in whole mount RPE/choroid preparations labeled with phalloidin. Photoreceptors in the older DJ-1 KO mice displayed decreased immunoreactivity to rhodopsin and localized reduction in cone markers compared to the wild-type control group. Lower levels of activated Nrf2 were evident in retina/RPE lysates in both young and old DJ-1 KO mouse groups compared to wild-type control levels. Conversely, higher levels of protein carbonyl derivatives and iNOS immunoreactivity were detected in retina/RPE lysates from both young and old DJ-1 KO mice. These results demonstrate that DJ-1 KO mice display progressive signs of retinal/RPE degeneration in association with higher levels of oxidative stress markers. Collectively this analysis indicates that DJ-1 plays an important role in protecting photoreceptors and RPE from oxidative damage during aging.
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Affiliation(s)
- Vera L Bonilha
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, Cleveland, OH 44195, USA; Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
| | - Brent A Bell
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Mary E Rayborn
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Ivy S Samuels
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA; Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH 44106, USA
| | - Anna King
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Joe G Hollyfield
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, Cleveland, OH 44195, USA; Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Chengsong Xie
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
| | - Huaibin Cai
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
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22
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Lyzogubov VV, Bora PS, Wu X, Horn LE, de Roque R, Rudolf XV, Atkinson JP, Bora NS. The Complement Regulatory Protein CD46 Deficient Mouse Spontaneously Develops Dry-Type Age-Related Macular Degeneration-Like Phenotype. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 186:2088-2104. [PMID: 27295359 PMCID: PMC4973660 DOI: 10.1016/j.ajpath.2016.03.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 03/28/2016] [Accepted: 03/31/2016] [Indexed: 11/20/2022]
Abstract
In the mouse, membrane cofactor protein (CD46), a key regulator of the alternative pathway of the complement system, is only expressed in the eye and on the inner acrosomal membrane of spermatozoa. We noted that although Cd46(-/-) mice have normal systemic alternative pathway activating ability, lack of CD46 leads to dysregulated complement activation in the eye, as evidenced by increased deposition of C5b-9 in the retinal pigment epithelium (RPE) and choroid. A knockout of CD46 induced the following cardinal features of human dry age-related macular degeneration (AMD) in 12-month-old male and female mice: accumulation of autofluorescent material in and hypertrophy of the RPE, dense deposits in and thickening of Bruch's membrane, loss of photoreceptors, cells in subretinal space, and a reduction of choroidal vessels. Collectively, our results demonstrate spontaneous age-related degenerative changes in the retina, RPE, and choroid of Cd46(-/-) mice that are consistent with human dry AMD. These findings provide the exciting possibility of using Cd46(-/-) mice as a convenient and reliable animal model for dry AMD. Having such a relatively straight-forward model for dry AMD should provide valuable insights into pathogenesis and a test model system for novel drug targets. More important, tissue-specific expression of CD46 gives the Cd46(-/-) mouse model of dry AMD a unique advantage over other mouse models using knockout strains.
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Affiliation(s)
- Valeriy V Lyzogubov
- Department of Ophthalmology, Jones Eye Institute, Pat and Willard Walker Eye Research Center, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Puran S Bora
- Department of Ophthalmology, Jones Eye Institute, Pat and Willard Walker Eye Research Center, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Xiaobo Wu
- Division of Rheumatology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Leah E Horn
- Department of Ophthalmology, Jones Eye Institute, Pat and Willard Walker Eye Research Center, University of Arkansas for Medical Sciences, Little Rock, Arkansas; Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Ryan de Roque
- Department of Ophthalmology, Jones Eye Institute, Pat and Willard Walker Eye Research Center, University of Arkansas for Medical Sciences, Little Rock, Arkansas; University of Arkansas for Medical Sciences, College of Medicine, Little Rock, Arkansas
| | - Xeniya V Rudolf
- Department of Ophthalmology, Jones Eye Institute, Pat and Willard Walker Eye Research Center, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - John P Atkinson
- Division of Rheumatology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Nalini S Bora
- Department of Ophthalmology, Jones Eye Institute, Pat and Willard Walker Eye Research Center, University of Arkansas for Medical Sciences, Little Rock, Arkansas; Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas.
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23
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Rowan S, Taylor A. Gene-Diet Interactions in Age-Related Macular Degeneration. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:95-101. [PMID: 26427399 DOI: 10.1007/978-3-319-17121-0_14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
Age-related macular degeneration (AMD) is a prevalent blinding disease, accounting for roughly 50 % of blindness in developed nations. Very significant advances have been made in terms of discovering genetic susceptibilities to AMD as well as dietary risk factors. To date, nutritional supplementation is the only available treatment option for the dry form of the disease known to slow progression of AMD. Despite an excellent understanding of genes and nutrition in AMD, there is remarkably little known about gene-diet interactions that may identify efficacious approaches to treat individuals. This review will summarize our current understanding of gene-diet interactions in AMD with a focus on animal models and human epidemiological studies.
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Affiliation(s)
- Sheldon Rowan
- USDA-JM Human Nutrition Research Center on Aging (HNRCA), Tufts University, 02111, Boston, MA, USA. .,Department of Ophthalmology, Tufts University School of Medicine, 02111, Boston, MA, USA.
| | - Allen Taylor
- USDA-JM Human Nutrition Research Center on Aging (HNRCA), Tufts University, 02111, Boston, MA, USA. .,Department of Ophthalmology, Tufts University School of Medicine, 02111, Boston, MA, USA. .,Friedman School of Nutrition Science and Policy, Tufts University, 02111, Boston, MA, USA.
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Extracellular Matrix Alterations and Deposit Formation in AMD. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:53-8. [PMID: 26427393 DOI: 10.1007/978-3-319-17121-0_8] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Age related macular degeneration (AMD) is the primary cause of vision loss in the western world (Friedman et al., Arch Ophthalmol 122:564-572, 2004). The first clinical indication of AMD is the presence of drusen. However, with age and prior to the formation of drusen, extracellular basal deposits accumulate between the retinal pigment epithelium (RPE) and Bruch's membrane (BrM). Many studies on the molecular composition of the basal deposits and drusen have demonstrated the presence of extracellular matrix (ECM) proteins, complement components and cellular debris. The evidence reviewed here suggests that alteration in RPE cell function might be the primary cause for the accumulation of ECM and cellular debri found in basal deposits. Further studies are obviously needed in order to unravel the specific pathways that lead to abnormal formation of ECM and complement activation.
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Aredo B, Li T, Chen X, Zhang K, Wang CXZ, Gou D, Zhao B, He Y, Ufret-Vincenty RL. A chimeric Cfh transgene leads to increased retinal oxidative stress, inflammation, and accumulation of activated subretinal microglia in mice. Invest Ophthalmol Vis Sci 2015; 56:3427-40. [PMID: 26030099 DOI: 10.1167/iovs.14-16089] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
PURPOSE Variants of complement factor H (Cfh) affecting short consensus repeats (SCRs) 6 to 8 increase the risk of age-related macular degeneration. Our aim was to explore the effect of expressing a Cfh variant on the in vivo susceptibility of the retina and RPE to oxidative stress and inflammation, using chimeric Cfh transgenic mice (chCfhTg). METHODS The chCfhTg and age-matched C57BL/6J (B6) mice were subjected to oxidative stress by either normal aging, or by exposure to a combination of oral hydroquinone (0.8% HQ) and increased light. Eyes were collected for immunohistochemistry of RPE-choroid flat mounts and of retinal sections, ELISA, electron microscopy, and RPE/microglia gene expression analysis. RESULTS Aging mice to 2 years led to an increased accumulation of basal laminar deposits, subretinal microglia/macrophages (MG/MΦ) staining for CD16 and for malondialdehyde (MDA), and MDA-modified proteins in the retina in chCfhTg compared to B6 mice. The chCfhTg mice maintained on HQ diet and increased light showed greater deposition of basal laminar deposits, more accumulation of fundus spots suggestive of MG/MΦ, and increased deposition of C3d in the sub-RPE space, compared to controls. In addition, chCfhTg mice demonstrated upregulation of NLRP3, IP-10, CD68, and TREM-2 in the RNA isolates from RPE/MG/MΦ. CONCLUSIONS Expression of a Cfh transgene introducing a variant in SCRs 6 to 8 was sufficient to lead to increased retinal/RPE susceptibility to oxidative stress, a proinflammatory MG/MΦ phenotype, and a proinflammatory RPE/MG/MΦ gene expression profile in a transgenic mouse model. Our data suggest that altered interactions of Cfh with MDA-modified proteins may be relevant in explaining the effects of the Cfh variant.
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Affiliation(s)
- Bogale Aredo
- Department of Ophthalmology UT Southwestern Medical Center, Dallas, Texas, United States
| | - Tao Li
- Department of Ophthalmology UT Southwestern Medical Center, Dallas, Texas, United States 2Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Xiao Chen
- Department of Ophthalmology UT Southwestern Medical Center, Dallas, Texas, United States
| | - Kaiyan Zhang
- Department of Ophthalmology UT Southwestern Medical Center, Dallas, Texas, United States
| | - Cynthia Xin-Zhao Wang
- Department of Ophthalmology UT Southwestern Medical Center, Dallas, Texas, United States
| | - Darlene Gou
- Department of Ophthalmology UT Southwestern Medical Center, Dallas, Texas, United States
| | - Biren Zhao
- Department of Ophthalmology UT Southwestern Medical Center, Dallas, Texas, United States
| | - Yuguang He
- Department of Ophthalmology UT Southwestern Medical Center, Dallas, Texas, United States
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Michel S, Canonne M, Arnould T, Renard P. Inhibition of mitochondrial genome expression triggers the activation of CHOP-10 by a cell signaling dependent on the integrated stress response but not the mitochondrial unfolded protein response. Mitochondrion 2015; 21:58-68. [PMID: 25643991 DOI: 10.1016/j.mito.2015.01.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 01/10/2015] [Accepted: 01/20/2015] [Indexed: 12/29/2022]
Abstract
Mitochondria-to-nucleus communication, known as retrograde signaling, is important to adjust the nuclear gene expression in response to organelle dysfunction. Among the transcription factors described to respond to mitochondrial stress, CHOP-10 is activated by respiratory chain inhibition, mitochondrial accumulation of unfolded proteins and mtDNA mutations. In this study, we show that altered/impaired expression of mtDNA induces CHOP-10 expression in a signaling pathway that depends on the eIF2α/ATF4 axis of the integrated stress response rather than on the mitochondrial unfolded protein response.
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Affiliation(s)
- Sebastien Michel
- Laboratory of Biochemistry and Cell Biology (URBC), NAmur Research Institute for LIfe Sciences (NARILIS), University of Namur (UNamur), 61 rue de Bruxelles, 5000 Namur, Belgium
| | - Morgane Canonne
- Laboratory of Biochemistry and Cell Biology (URBC), NAmur Research Institute for LIfe Sciences (NARILIS), University of Namur (UNamur), 61 rue de Bruxelles, 5000 Namur, Belgium
| | - Thierry Arnould
- Laboratory of Biochemistry and Cell Biology (URBC), NAmur Research Institute for LIfe Sciences (NARILIS), University of Namur (UNamur), 61 rue de Bruxelles, 5000 Namur, Belgium
| | - Patricia Renard
- Laboratory of Biochemistry and Cell Biology (URBC), NAmur Research Institute for LIfe Sciences (NARILIS), University of Namur (UNamur), 61 rue de Bruxelles, 5000 Namur, Belgium.
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Levy E. Insights from human congenital disorders of intestinal lipid metabolism. J Lipid Res 2014; 56:945-62. [PMID: 25387865 DOI: 10.1194/jlr.r052415] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Indexed: 12/24/2022] Open
Abstract
The intestine must challenge the profuse daily flux of dietary fat that serves as a vital source of energy and as an essential component of cell membranes. The fat absorption process takes place in a series of orderly and interrelated steps, including the uptake and translocation of lipolytic products from the brush border membrane to the endoplasmic reticulum, lipid esterification, Apo synthesis, and ultimately the packaging of lipid and Apo components into chylomicrons (CMs). Deciphering inherited disorders of intracellular CM elaboration afforded new insight into the key functions of crucial intracellular proteins, such as Apo B, microsomal TG transfer protein, and Sar1b GTPase, the defects of which lead to hypobetalipoproteinemia, abetalipoproteinemia, and CM retention disease, respectively. These "experiments of nature" are characterized by fat malabsorption, steatorrhea, failure to thrive, low plasma levels of TGs and cholesterol, and deficiency of liposoluble vitamins and essential FAs. After summarizing and discussing the functions and regulation of these proteins for reader's comprehension, the current review focuses on their specific roles in malabsorptions and dyslipidemia-related intestinal fat hyperabsorption while dissecting the spectrum of clinical manifestations and managements. The influence of newly discovered proteins (proprotein convertase subtilisin/kexin type 9 and angiopoietin-like 3 protein) on fat absorption has also been provided. Finally, it is stressed how the overexpression or polymorphism status of the critical intracellular proteins promotes dyslipidemia and cardiometabolic disorders.
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Affiliation(s)
- Emile Levy
- Research Centre, CHU Sainte-Justine and Department of Nutrition, Université de Montréal, Montreal, Quebec H3T 1C5, Canada
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Fujihara M, Cano M, Handa JT. Mice that produce ApoB100 lipoproteins in the RPE do not develop drusen yet are still a valuable experimental system. Invest Ophthalmol Vis Sci 2014; 55:7285-95. [PMID: 25316721 DOI: 10.1167/iovs.14-15195] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Mice typically produce apolipoprotein B (apoB)-48 and not apoB100. Apolipoprotein B100 accumulates in Bruch's membrane prior to basal deposit and drusen formation during the onset of AMD, raising the possibility that they are a trigger for these Bruch's membrane alterations. The purpose herein, was to determine whether mice that predominantly produce apoB100 develop features of AMD. METHODS The eyes of mice that produce apoB100 were examined for apoB100 synthesis, cholesteryl esterase/filipin labeling for cholesteryl esters, and transmission electron microscopy for lipid particles and phenotype. RESULTS Apolipoprotein B100 was abundant in the RPE-choroid of apoB100, but not wild-type mice by Western blot analysis. The apolipoprotein B100,(35)S-radiolabeled and immunoprecipitated from RPE explants, confirmed that apoB100 was synthesized by RPE. Apolipoprotein B100, but not control mice, had cholesteryl esters and lipid particles in Bruch's membrane. Immunoreactivity of ApoB100 was present in the RPE and Bruch's membrane, but not choroidal endothelium of apoB100 mice. Ultrastructural changes were consistent with aging, but not AMD when aged up to 18 months. The induction of advanced glycation end products to alter Bruch's membrane, did not promote basal linear deposit or drusen formation. CONCLUSIONS Mice that produce apoB100 in the RPE and liver secrete lipoproteins into Bruch's membrane, but not to the extent that distinct features of AMD develop, which suggests that either additional lipoprotein accumulation or additional factors are necessary to initiate their formation.
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Affiliation(s)
- Masashi Fujihara
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - Marisol Cano
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - James T Handa
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
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Bartels ED, Ploug T, Størling J, Mandrup-Poulsen T, Nielsen LB. Skeletal muscle apolipoprotein B expression reduces muscular triglyceride accumulation. Scand J Clin Lab Invest 2014; 74:351-7. [DOI: 10.3109/00365513.2014.893446] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Ananth S, Gnana-Prakasam JP, Bhutia YD, Veeranan-Karmegam R, Martin PM, Smith SB, Ganapathy V. Regulation of the cholesterol efflux transporters ABCA1 and ABCG1 in retina in hemochromatosis and by the endogenous siderophore 2,5-dihydroxybenzoic acid. Biochim Biophys Acta Mol Basis Dis 2014; 1842:603-12. [PMID: 24462739 DOI: 10.1016/j.bbadis.2014.01.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 01/08/2014] [Accepted: 01/13/2014] [Indexed: 01/19/2023]
Abstract
Hypercholesterolemia and polymorphisms in the cholesterol exporter ABCA1 are linked to age-related macular degeneration (AMD). Excessive iron in retina also has a link to AMD pathogenesis. Whether these findings mean a biological/molecular connection between iron and cholesterol is not known. Here we examined the relationship between retinal iron and cholesterol using a mouse model (Hfe(-/-)) of hemochromatosis, a genetic disorder of iron overload. We compared the expression of the cholesterol efflux transporters ABCA1 and ABCG1 and cholesterol content in wild type and Hfe(-/-) mouse retinas. We also investigated the expression of Bdh2, the rate-limiting enzyme in the synthesis of the endogenous siderophore 2,5-dihydroxybenzoic acid (2,5-DHBA) in wild type and Hfe(-/-) mouse retinas, and the influence of this siderophore on ABCA1/ABCG1 expression in retinal pigment epithelium. We found that ABCA1 and ABCG1 were expressed in all retinal cell types, and that their expression was decreased in Hfe(-/-) retina. This was accompanied with an increase in retinal cholesterol content. Bdh2 was also expressed in all retinal cell types, and its expression was decreased in hemochromatosis. In ARPE-19 cells, 2,5-DHBA increased ABCA1/ABCG1 expression and decreased cholesterol content. This was not due to depletion of free iron because 2,5-DHBA (a siderophore) and deferiprone (an iron chelator) had opposite effects on transferrin receptor expression and ferritin levels. We conclude that iron is a regulator of cholesterol homeostasis in retina and that removal of cholesterol from retinal cells is impaired in hemochromatosis. Since excessive cholesterol is pro-inflammatory, hemochromatosis might promote retinal inflammation via cholesterol in AMD.
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Affiliation(s)
- Sudha Ananth
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, GA 30912, USA
| | - Jaya P Gnana-Prakasam
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, GA 30912, USA
| | - Yangzom D Bhutia
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, GA 30912, USA
| | | | - Pamela M Martin
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, GA 30912, USA
| | - Sylvia B Smith
- Department of Cellular Biology and Anatomy, Georgia Regents University, Augusta, GA 30912, USA
| | - Vadivel Ganapathy
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, GA 30912, USA.
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Ardeljan D, Chan CC. Aging is not a disease: distinguishing age-related macular degeneration from aging. Prog Retin Eye Res 2013; 37:68-89. [PMID: 23933169 PMCID: PMC3830684 DOI: 10.1016/j.preteyeres.2013.07.003] [Citation(s) in RCA: 168] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 07/29/2013] [Accepted: 07/30/2013] [Indexed: 12/18/2022]
Abstract
Age-related macular degeneration (AMD) is a disease of the outer retina, characterized most significantly by atrophy of photoreceptors and retinal pigment epithelium accompanied with or without choroidal neovascularization. Development of AMD has been recognized as contingent on environmental and genetic risk factors, the strongest being advanced age. In this review, we highlight pathogenic changes that destabilize ocular homeostasis and promote AMD development. With normal aging, photoreceptors are steadily lost, Bruch's membrane thickens, the choroid thins, and hard drusen may form in the periphery. In AMD, many of these changes are exacerbated in addition to the development of disease-specific factors such as soft macular drusen. Para-inflammation, which can be thought of as an intermediate between basal and robust levels of inflammation, develops within the retina in an attempt to maintain ocular homeostasis, reflected by increased expression of the anti-inflammatory cytokine IL-10 coupled with shifts in macrophage plasticity from the pro-inflammatory M1 to the anti-inflammatory M2 polarization. In AMD, imbalances in the M1 and M2 populations together with activation of retinal microglia are observed and potentially contribute to tissue degeneration. Nonetheless, the retina persists in a state of chronic inflammation and increased expression of certain cytokines and inflammasomes is observed. Since not everyone develops AMD, the vital question to ask is how the body establishes a balance between normal age-related changes and the pathological phenotypes in AMD.
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Affiliation(s)
- Daniel Ardeljan
- Immunopathology Section, Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA; Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Garland DL, Fernandez-Godino R, Kaur I, Speicher KD, Harnly JM, Lambris JD, Speicher DW, Pierce EA. Mouse genetics and proteomic analyses demonstrate a critical role for complement in a model of DHRD/ML, an inherited macular degeneration. Hum Mol Genet 2013; 23:52-68. [PMID: 23943789 DOI: 10.1093/hmg/ddt395] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Macular degenerations, inherited and age related, are important causes of vision loss. Human genetic studies have suggested perturbation of the complement system is important in the pathogenesis of age-related macular degeneration. The mechanisms underlying the involvement of the complement system are not understood, although complement and inflammation have been implicated in drusen formation. Drusen are an early clinical hallmark of inherited and age-related forms of macular degeneration. We studied one of the earliest stages of macular degeneration which precedes and leads to the formation of drusen, i.e. the formation of basal deposits. The studies were done using a mouse model of the inherited macular dystrophy Doyne Honeycomb Retinal Dystrophy/Malattia Leventinese (DHRD/ML) which is caused by a p.Arg345Trp mutation in EFEMP1. The hallmark of DHRD/ML is the formation of drusen at an early age, and gene targeted Efemp1(R345W/R345W) mice develop extensive basal deposits. Proteomic analyses of Bruch's membrane/choroid and Bruch's membrane in the Efemp1(R345W/R345W) mice indicate that the basal deposits comprise normal extracellular matrix (ECM) components present in abnormal amounts. The proteomic analyses also identified significant changes in proteins with immune-related function, including complement components, in the diseased tissue samples. Genetic ablation of the complement response via generation of Efemp1(R345W/R345W):C3(-/-) double-mutant mice inhibited the formation of basal deposits. The results demonstrate a critical role for the complement system in basal deposit formation, and suggest that complement-mediated recognition of abnormal ECM may participate in basal deposit formation in DHRD/ML and perhaps other macular degenerations.
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Evangelisti C, Bianco F, Pradella LM, Puliti A, Goldoni A, Sbrana I, Rossi M, Vargiolu M, Seri M, Romeo G, Stanghellini V, de Giorgio R, Bonora E. Apolipoprotein B is a new target of the GDNF/RET and ET-3/EDNRB signalling pathways. Neurogastroenterol Motil 2012; 24:e497-508. [PMID: 22897442 DOI: 10.1111/j.1365-2982.2012.01998.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
BACKGROUND GDNF/RET and Endothelin-3 (ET-3)/EDNRB regulate survival, differentiation, migration, and proliferation of neural crest-derived cells. Although several RET and EDNRB signalling mediators have been characterized, most of the genes targeted by these two pathways are still largely unknown. We focused our study on apolipoprotein B (APOB) as a novel target gene of the RET and EDNRB pathways, based on previous data obtained using a Caenorhabditis elegans strain mutant for the homologue of mammalian ECE1. METHODS Molecular and cellular studies of Apob were performed in the murine Neuro2a cells, an in vitro model for studying neural crest-derived cell development, along with a mouse knock-in for the Hirschsprung-associated mutation Ret(C620R). Silencing for Apob and Ret has been performed via shRNA. KEY RESULTS GDNF/RET and ET-3/EDNRB cooperated in inducing neuronal differentiation resulting in Apob activation in Neuro2a cell line. Apob expression was downregulated in mouse embryos homozygous for the Ret(C620R) mutation and presenting a severe Hirschsprung phenotype. Ret silencing prevented Apob expression increase. MAPK P38 kinase activation evoked Apob expression via GDNF/RET signalling in Neuro2a cells. A p53-dependent repressor element in Apob promoter resulted in a reduced Apob expression. Silencing of Apob reduced HuD protein expression. CONCLUSIONS & INFERENCES Apob is a novel downstream target of the RET/EDNRB pathways with a role in neuronal survival and maintenance, as indicated by its effect on HuD expression. Our data provide a conceptual framework to investigate and establish the role of APOB gene in severe gut dysmotility.
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Affiliation(s)
- C Evangelisti
- Medical Genetics Unit, St.Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
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Pennesi ME, Neuringer M, Courtney RJ. Animal models of age related macular degeneration. Mol Aspects Med 2012; 33:487-509. [PMID: 22705444 DOI: 10.1016/j.mam.2012.06.003] [Citation(s) in RCA: 271] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Age related macular degeneration (AMD) is the leading cause of vision loss of those over the age of 65 in the industrialized world. The prevalence and need to develop effective treatments for AMD has lead to the development of multiple animal models. AMD is a complex and heterogeneous disease that involves the interaction of both genetic and environmental factors with the unique anatomy of the human macula. Models in mice, rats, rabbits, pigs and non-human primates have recreated many of the histological features of AMD and provided much insight into the underlying pathological mechanisms of this disease. In spite of the large number of models developed, no one model yet recapitulates all of the features of human AMD. However, these models have helped reveal the roles of chronic oxidative damage, inflammation and immune dysregulation, and lipid metabolism in the development of AMD. Models for induced choroidal neovascularization have served as the backbone for testing new therapies. This article will review the diversity of animal models that exist for AMD as well as their strengths and limitations.
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Affiliation(s)
- Mark E Pennesi
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA.
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Hunter A, Spechler PA, Cwanger A, Song Y, Zhang Z, Ying GS, Hunter AK, Dezoeten E, Dunaief JL. DNA methylation is associated with altered gene expression in AMD. Invest Ophthalmol Vis Sci 2012; 53:2089-105. [PMID: 22410570 DOI: 10.1167/iovs.11-8449] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PURPOSE Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly. Evidence suggests oxidative stress plays a role in the disease. To assess the potential contribution of epigenetic regulation of antioxidant genes relevant to AMD pathogenesis, we evaluated DNA methylation, a tissue-specific genetic modulation that affects gene expression. METHODS Using the Infinium HumanMethylation27 Illumina platform, we performed DNA bisulfite sequencing to compare the methylation status in postmortem retina pigment epithelium (RPE)/choroid between patients with AMD and age-matched controls. Gene expression was assessed with the Affymetrix Exon Array. TaqMan gene expression assays were used for relative quantification (RT-PCR) confirmation of the expression array results: Glutathione S-transferase isoform mu1 (GSTM1) and mu5 (GSTM5) promoter methylation was confirmed by CpG island bisulfite pyrosequencing. To assess protein levels and localization, we used Western analysis, immunohistochemistry, and immunofluorescence with murine and human samples. RESULTS The mRNA levels of GSTM1 and GSTM5 were significantly reduced in AMD versus age-matched controls in RPE/choroid and neurosensory retina (NSR), which corresponded to hypermethylation of the GSTM1 promoter. mRNA and protein levels were decreased (RPE to a greater extent than NSR) in AMD postmortem samples, irrespective of age. Immunohistochemistry and immunofluorescence confirm the presence of the enzymes in the NSR and RPE. CONCLUSIONS Comparison of DNA methylation, together with mRNA levels, revealed significant differences between AMD versus normal retinas. The evidence presented suggests that GSTM1 and GSTM5 undergo epigenetic repression in AMD RPE/choroid, which may increase susceptibility to oxidative stress in AMD retinas.
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Affiliation(s)
- Allan Hunter
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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Weikel KA, Fitzgerald P, Shang F, Caceres MA, Bian Q, Handa JT, Stitt AW, Taylor A. Natural history of age-related retinal lesions that precede AMD in mice fed high or low glycemic index diets. Invest Ophthalmol Vis Sci 2012; 53:622-32. [PMID: 22205601 DOI: 10.1167/iovs.11-8545] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
PURPOSE Epidemiologic data indicate that people who consume low glycemic index (GI) diets are at reduced risk for the onset and progression of age-related macular degeneration (AMD). The authors sought corroboration of this observation in an animal model. METHODS Five- and 16-month-old C57BL/6 mice were fed high or low GI diets until they were 17 and 23.5 months of age, respectively. Retinal lesions were evaluated by transmission electron microscopy, and advanced glycation end products (AGEs) were evaluated by immunohistochemistry. RESULTS Retinal lesions including basal laminar deposits, loss of basal infoldings, and vacuoles in the retinal pigment epithelium were more prevalent in the 23.5- than in the 17-month-old mice. Within each age group, consumption of a high GI diet increased the risk for lesions and the risk for photoreceptor abnormalities and accumulation of AGEs. CONCLUSIONS Consuming high GI diets accelerates the appearance of age-related retinal lesions that precede AMD in mice, perhaps by increasing the deposition of toxic AGEs in the retina. The data support the hypothesis that consuming lower GI diets, or simulation of their effects with nutraceuticals or drugs, may protect against AMD. The high GI-fed C57BL/6 mouse is a new model of age-related retinal lesions that precede AMD and mimic the early stages of disease and may be useful for drug discovery.
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Affiliation(s)
- Karen A Weikel
- Laboratory for Nutrition and Vision Research, JM-USDA Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts 02111, USA
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Yin L, Shi Y, Liu X, Zhang H, Gong Y, Gu Q, Wu X, Xu X. A Rat Model for Studying the Biological Effects of Circulating LDL in the Choriocapillaris-BrM-RPE Complex. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 180:541-9. [DOI: 10.1016/j.ajpath.2011.10.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 10/11/2011] [Accepted: 10/13/2011] [Indexed: 10/15/2022]
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Abstract
Ageing is the largest risk factor for age-related macular degeneration (AMD), and soft drusen and basal linear deposits are lipid-rich extracellular lesions specific to AMD. Oil red O binding neutral lipid represents a major age-related deposition in the Bruch membrane (BrM) and the first identified druse component. Decades after these seminal observations, a natural history of neutral lipid deposition has been articulated and a biochemical model proposed. Results obtained with multiple biochemical, histochemical, and ultrastructural methods, and supported indirectly by epidemiology, suggest that the RPE secretes apolipoprotein B (apoB)-lipoprotein particles of unusual composition into BrM, where they accumulate with age eventually forming a lipid wall, a precursor of basal linear deposit. The authors propose that constituents of these lesions interact with reactive oxygen species to form pro-inflammatory peroxidised lipids that elicit neovascularisation. Here, the authors summarise key evidence supporting both accumulation of BrM lipoproteins leading to lesion formation and lipoprotein production by the RPE. The authors update their model with genetic associations between AMD and genes historically associated with plasma HDL metabolism, and suggest future directions for research and therapeutic strategies based on an oil-spill analogy.
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Affiliation(s)
- Christine A Curcio
- Department of Ophthalmology, EyeSight Foundation of Alabama Vision Science Laboratories Room 360, University of Alabama School of Medicine, Birmingham, AL 35294-0019, USA.
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Kishan AU, Modjtahedi BS, Martins EN, Modjtahedi SP, Morse LS. Lipids and age-related macular degeneration. Surv Ophthalmol 2011; 56:195-213. [PMID: 21439604 DOI: 10.1016/j.survophthal.2010.08.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Revised: 08/29/2010] [Accepted: 08/31/2010] [Indexed: 01/17/2023]
Abstract
Given the considerable public health burden imposed by age-related macular degeneration (AMD), much effort has been directed towards elucidating principles of pathogenesis in order to identify risk factors and develop preventive measures and treatments. Together with epidemiological evidence linking cardiovascular risk factors with AMD risk and basic science work examining the role of lipid metabolism in AMD, numerous human studies have assayed a potential relationship between dietary lipids and the development of AMD. We examine the evidence for a role for lipid metabolism in AMD, highlighting key basic biochemical principles, work in animal models, and relevant human studies. The topics of lipoprotein modulation and omega-3 fatty acid intake receive special attention from both a basic science and clinical study standpoint. The evidence suggests that consumption of omega-3 fatty acids, perhaps in concert with antioxidants, may constitute a rational preventative strategy against AMD development, though, absent an appropriately developed double-blind, randomized control trial, insufficient data exist to recommend implementation in the clinical setting at this time.
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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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Ramkumar HL, Zhang J, Chan CC. Retinal ultrastructure of murine models of dry age-related macular degeneration (AMD). Prog Retin Eye Res 2010; 29:169-90. [PMID: 20206286 DOI: 10.1016/j.preteyeres.2010.02.002] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Age-related macular degeneration (AMD) is the most prevalent form of irreversible blindness worldwide in the elderly population. The pathology of dry AMD consists of macular degeneration of photoreceptors and the RPE, lipofuscin (A2E) accumulation, and drusen formation. Mice have been widely used for generating models that simulate human AMD features for investigating the pathogenesis, treatment and prevention of the disease. Although the mouse has no macula, focal atrophy of photoreceptors and RPE, lipofuscin accumulation, and increased A2E can develop in aged mouse eyes. However, drusen are rarely seen in mice because of their simpler Bruch's membrane and different process of lipofuscin extrusion compared with humans. Thus, analyzing basal deposits at the ultrastructural level and understanding the ultrastructural pathologic differences between various mouse AMD models are critical to comprehending the significance of research findings and response to possible therapeutic options for dry AMD. Based on the multifactorial pathogenesis of AMD, murine dry AMD models can be classified into three groups. First, genetically engineered mice that target genes related to juvenile macular dystrophies are the most common models, and they include abcr(-/-) (Stargardt disease), transgenic ELOVL4 (Stargardt-3 dominant inheritary disease), Efemp1(R345W/R345W) (Doyne honeycomb retinal dystrophy), and Timp3(S156C/S156C) (Sorsby fundus dystrophy) mice. Other murine models target genes relevant to AMD, including inflammatory genes such as Cfh(-/-), Ccl2(-/-), Ccr2(-/-), Cx3cr1(-/-), and Ccl2(-/-)/cx3cr1(-/-), oxidative stress associated genes such as Sod1(-/-) and Sod2 knockdown, metabolic pathway genes such as neprilysin(-/-) (amyloid beta), transgenic mcd/mcd (cathepsin D), Cp(-/-)/Heph(-/Y) (ferroxidase ceruloplasmin/hepaestin, iron metabolism), and transgenic ApoE4 on high fat and high cholesterol diet (lipid metabolism). Second, mice have also been immunologically manipulated by immunization with carboxyethylpyrrole (CEP), an oxidative fragment of DHA found in drusen, and found to present with dry AMD features. Third, natural mouse strains such as arrd2/arrd2 (Mdm gene mutation) and the senescence accelerated mice (SAM) spontaneously develop features of dry AMD like photoreceptor atrophy and thickening of Bruch's membrane. All the aforementioned models develop retinal lesions with various features that simulate dry AMD lesions: focal photoreceptor degeneration, abnormal RPE with increased lipofuscin, basal infolding, decreased melanosomes and degeneration. However, Bruch's membrane changes are less common. Most mice develop retinal lesions at an older age (6-24 months, depending on the models), while the Ccl2(-/-)/cx3cr1(-/-) mice develop lesions by 4-6 weeks. Although murine models present various degrees of retinal and/or RPE degeneration, classical drusen is extremely rare. Using electron microscopy, small drusenoid deposits are found between RPE and Bruch's membrane in a few models including Efemp1(R345W/R345W), Ccl2(-/-)/cx3cr1(-/-), neprilysin(-/-), transgenic mcd/mcd, and ApoE4 transgenic mice on a high fat diet. High A2E levels are measured in the retinas of abcr(-/-), transgenic ELOVL4, and Ccl2(-/-)/cx3cr1(-/-) mice. In summary, murine models provide useful tools for studying AMD pathogenesis and evaluating novel therapies for this disease. This review compares the major dry AMD murine models and discusses retinal pathology at the ultrastructural level.
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Affiliation(s)
- Hema L Ramkumar
- Immunopathology Section, Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, MD 20892-1857, USA
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Wang AL, Neufeld AH. Smoking mice: A potential model for studying accumulation of drusen-like material on Bruch’s membrane. Vision Res 2010; 50:638-42. [DOI: 10.1016/j.visres.2009.08.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Revised: 08/10/2009] [Accepted: 08/15/2009] [Indexed: 11/25/2022]
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Krzystanek M, Pedersen TX, Bartels ED, Kjaehr J, Straarup EM, Nielsen LB. Expression of apolipoprotein B in the kidney attenuates renal lipid accumulation. J Biol Chem 2010; 285:10583-90. [PMID: 20103594 DOI: 10.1074/jbc.m109.078006] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The ability to produce apolipoprotein (apo) B-containing lipoproteins enables hepatocytes, enterocytes, and cardiomyocytes to export triglycerides. In this study, we examined secretion of apoB-containing lipoproteins from mouse kidney and its putative impact on triglyceride accumulation in the tubular epithelium. Mouse kidney expressed both the apoB and microsomal triglyceride transfer protein genes, which permit lipoprotein formation. To examine de novo lipoprotein secretion, kidneys from human apoB-transgenic mice were minced and placed in medium with (35)S-amino acids. Upon sucrose gradient ultracentrifugation of the labeled medium, fractions were analyzed by apoB immunoprecipitation. (35)S-Labeled apoB100 was recovered in approximately 1.03-1.04 g/ml lipoproteins (i.e. similar to the density of plasma low density lipoproteins). Immunohistochemistry of kidney sections suggested that apoB mainly is produced by tubular epithelial cells. ApoB expression in the kidney cortex was reduced approximately 90% in vivo by treating wild type mice with apoB-antisense locked nucleic acid oligonucleotide. Inhibition of apoB expression increased fasting-induced triglyceride accumulation in the kidney cortex by 20-25% (p = 0.008). Cholesterol stores were unaffected. Treatment with control oligonucleotides with 1 or 4 mismatching base pairs affected neither the triglyceride nor the cholesterol content of the kidney cortex. The results suggest that mammalian kidney secretes apoB100-containing lipoproteins. One biological effect may be to dampen excess storage of triglycerides in proximal tubule cells.
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Affiliation(s)
- Marcin Krzystanek
- Department of Clinical Biochemistry, Rigshospitalet, DK-2100 Copenhagen
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Hecker LA, Edwards AO. Genetic control of complement activation in humans and age related macular degeneration. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 703:49-62. [PMID: 20711706 DOI: 10.1007/978-1-4419-5635-4_4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The major focus of our research is to understand how age-related macular degeneration (AMD) develops. It is known that genetic variation can explain much of the risk of developing AMD. However, we do not know what controls the transition between a normal fundus and the extensive accumulation of subretinal inflammatory material that we recognize as drusen in AMD. We do know that the accumulation of this inflammatory material that characterizes the maculopathy underlying AMD is by far the most important predictor of late AMD. Late or advanced forms of AMD include geographic atrophy in which there is patchy death of the retina and exudation in which abnormal neovascularization invades the subretinal or subretinal pigment epithelial space. Thus, preventing the accumulation of the inflammatory debris underneath the retina could be expected to alleviate much of the vision loss from this devastating disease.
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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: 137] [Impact Index Per Article: 9.1] [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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