1
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Farnoodian M, Bose D, Barone F, Nelson LM, Boyle M, Jun B, Do K, Gordon W, Guerin MAK, Perera R, Ji JX, Cogliati T, Sharma R, Brooks BP, Bazan NG, Bharti K. Retina and RPE lipid profile changes linked with ABCA4 associated Stargardt's maculopathy. Pharmacol Ther 2023; 249:108482. [PMID: 37385300 PMCID: PMC10530239 DOI: 10.1016/j.pharmthera.2023.108482] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 06/20/2023] [Accepted: 06/26/2023] [Indexed: 07/01/2023]
Abstract
Stargardt maculopathy, caused predominantly by mutations in the ABCA4 gene, is characterized by an accumulation of non-degradable visual pigment derivative, lipofuscin, in the retinal pigment epithelium (RPE) - resulting in RPE atrophy. RPE is a monolayer tissue located adjacent to retinal photoreceptors and regulates their health and functioning; RPE atrophy triggers photoreceptor cell death and vision loss in Stargardt patients. Previously, ABCA4 mutations in photoreceptors were thought to be the major contributor to lipid homeostasis defects in the eye. Recently, we demonstrated that ABCA4 loss of function in the RPE leads to cell-autonomous lipid homeostasis defects. Our work underscores that an incomplete understanding of lipid metabolism and lipid-mediated signaling in the retina and RPE are potential causes for lacking treatments for this disease. Here we report altered lipidomic in mouse and human Stargardt models. This work provides the basis for therapeutics that aim to restore lipid homeostasis in the retina and the RPE.
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Affiliation(s)
- Mitra Farnoodian
- Ocular and Stem Cell Translational Research Section, National Eye Institute, National Institute of Health, Bethesda, MD, USA
| | - Devika Bose
- Ocular and Stem Cell Translational Research Section, National Eye Institute, National Institute of Health, Bethesda, MD, USA
| | - Francesca Barone
- Ocular and Stem Cell Translational Research Section, National Eye Institute, National Institute of Health, Bethesda, MD, USA
| | - Luke Mathew Nelson
- Ocular and Stem Cell Translational Research Section, National Eye Institute, National Institute of Health, Bethesda, MD, USA
| | - Marisa Boyle
- Ocular and Stem Cell Translational Research Section, National Eye Institute, National Institute of Health, Bethesda, MD, USA
| | - Bokkyoo Jun
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
| | - Khanh Do
- Faculty of Medicine, Phenikaa University, Hanoi, Viet Nam
| | - William Gordon
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
| | - Marie-Audrey Kautzmann Guerin
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
| | - Rasangi Perera
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
| | - Jeff X Ji
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
| | - Tiziana Cogliati
- Division of Aging Biology, National Institute on Aging, National Institute of Health, Bethesda, MD, USA
| | - Ruchi Sharma
- Ocular and Stem Cell Translational Research Section, National Eye Institute, National Institute of Health, Bethesda, MD, USA
| | - Brian P Brooks
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institute of Health, Bethesda, MD, USA
| | - Nicolas G Bazan
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
| | - Kapil Bharti
- Ocular and Stem Cell Translational Research Section, National Eye Institute, National Institute of Health, Bethesda, MD, USA.
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2
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Chen CT, Shao Z, Fu Z. Dysfunctional peroxisomal lipid metabolisms and their ocular manifestations. Front Cell Dev Biol 2022; 10:982564. [PMID: 36187472 PMCID: PMC9524157 DOI: 10.3389/fcell.2022.982564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 08/17/2022] [Indexed: 11/13/2022] Open
Abstract
Retina is rich in lipids and dyslipidemia causes retinal dysfunction and eye diseases. In retina, lipids are not only important membrane component in cells and organelles but also fuel substrates for energy production. However, our current knowledge of lipid processing in the retina are very limited. Peroxisomes play a critical role in lipid homeostasis and genetic disorders with peroxisomal dysfunction have different types of ocular complications. In this review, we focus on the role of peroxisomes in lipid metabolism, including degradation and detoxification of very-long-chain fatty acids, branched-chain fatty acids, dicarboxylic acids, reactive oxygen/nitrogen species, glyoxylate, and amino acids, as well as biosynthesis of docosahexaenoic acid, plasmalogen and bile acids. We also discuss the potential contributions of peroxisomal pathways to eye health and summarize the reported cases of ocular symptoms in patients with peroxisomal disorders, corresponding to each disrupted peroxisomal pathway. We also review the cross-talk between peroxisomes and other organelles such as lysosomes, endoplasmic reticulum and mitochondria.
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Affiliation(s)
- Chuck T. Chen
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Zhuo Shao
- Post-Graduate Medical Education, University of Toronto, Toronto, ON, Canada
- Division of Clinical and Metabolic Genetics, the Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
- The Genetics Program, North York General Hospital, University of Toronto, Toronto, ON, Canada
| | - Zhongjie Fu
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States
- *Correspondence: Zhongjie Fu,
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3
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West EL, Majunder P, Naeem A, Fernando M, O'Hara-Wright M, Lanning E, Kloc M, Ribeiro J, Ovando-Roche P, Shum IO, Jumbu N, Sampson R, Hayes M, Bainbridge JWB, Georgiadis A, Smith AJ, Gonzalez-Cordero A, Ali RR. Antioxidant and lipid supplementation improve the development of photoreceptor outer segments in pluripotent stem cell-derived retinal organoids. Stem Cell Reports 2022; 17:775-788. [PMID: 35334217 PMCID: PMC9023802 DOI: 10.1016/j.stemcr.2022.02.019] [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: 08/23/2021] [Revised: 02/26/2022] [Accepted: 02/28/2022] [Indexed: 01/01/2023] Open
Abstract
The generation of retinal organoids from human pluripotent stem cells (hPSC) is now a well-established process that in part recapitulates retinal development. However, hPSC-derived photoreceptors that exhibit well-organized outer segment structures have yet to be observed. To facilitate improved inherited retinal disease modeling, we determined conditions that would support outer segment development in maturing hPSC-derived photoreceptors. We established that the use of antioxidants and BSA-bound fatty acids promotes the formation of membranous outer segment-like structures. Using new protocols for hPSC-derived retinal organoid culture, we demonstrated improved outer segment formation for both rod and cone photoreceptors, including organized stacked discs. Using these enhanced conditions to generate iPSC-derived retinal organoids from patients with X-linked retinitis pigmentosa, we established robust cellular phenotypes that could be ameliorated following adeno-associated viral vector-mediated gene augmentation. These findings should aid both disease modeling and the development of therapeutic approaches for the treatment of photoreceptor disorders. Antioxidants and lipids are required for the formation of organized outer segments Both rod and cone hPSC-derived photoreceptors generate well-formed outer segments Improved conditions provide a robust model of X-linked retinitis pigmentosa type 3 Enhanced segment formation permits the evaluation of therapeutic interventions
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Affiliation(s)
- Emma L West
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Paromita Majunder
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Arifa Naeem
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Milan Fernando
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | - Emily Lanning
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Magdalena Kloc
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Joana Ribeiro
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | - Ian O Shum
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Neeraj Jumbu
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Robert Sampson
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Matt Hayes
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - James W B Bainbridge
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK; NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, City Road, London EC1V 2PD, UK
| | | | - Alexander J Smith
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | - Robin R Ali
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK; NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, City Road, London EC1V 2PD, UK; Kellogg Eye Center, University of Michigan, 1000 Wall Street, Ann Arbor, MI 48105, USA.
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4
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Sinclair AJ, Guo XF, Abedin L. Dietary Alpha-Linolenic Acid Supports High Retinal DHA Levels. Nutrients 2022; 14:nu14020301. [PMID: 35057481 PMCID: PMC8779487 DOI: 10.3390/nu14020301] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/06/2022] [Accepted: 01/10/2022] [Indexed: 02/01/2023] Open
Abstract
The retina requires docosahexaenoic acid (DHA) for optimal function. Alpha-linolenic acid (ALA) and DHA are dietary sources of retinal DHA. This research investigated optimizing retinal DHA using dietary ALA. Previous research identified 19% DHA in retinal phospholipids was associated with optimal retinal function in guinea pigs. Pregnant guinea pigs were fed dietary ALA from 2.8% to 17.3% of diet fatty acids, at a constant level of linoleic acid (LA) of 18% for the last one third of gestation and retinal DHA levels were assessed in 3-week-old offspring maintained on the same diets as their mothers. Retinal DHA increased in a linear fashion with the maximum on the diet with LA:ALA of 1:1. Feeding diets with LA:ALA of 1:1 during pregnancy and assessing retinal DHA in 3-week-old offspring was associated with optimized retinal DHA levels. We speculate that the current intakes of ALA in human diets, especially in relation to LA intakes, are inadequate to support high DHA levels in the retina.
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Affiliation(s)
- Andrew J. Sinclair
- Department of Nutrition, Dietetics and Food, School of Clinical Sciences, Monash University, Melbourne, VIC 3168, Australia
- Correspondence: ; Tel.: +61-(0)414-906-341
| | - Xiao-Fei Guo
- Institute of Nutrition & Health, College of Public Health, Qingdao University, Qingdao 266071, China;
| | - Lavinia Abedin
- Department of Food Science and Technology, School of Science, RMIT University, Melbourne, VIC 3001, Australia;
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5
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Lewandowski D, Sander CL, Tworak A, Gao F, Xu Q, Skowronska-Krawczyk D. Dynamic lipid turnover in photoreceptors and retinal pigment epithelium throughout life. Prog Retin Eye Res 2021; 89:101037. [PMID: 34971765 PMCID: PMC10361839 DOI: 10.1016/j.preteyeres.2021.101037] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 12/13/2021] [Accepted: 12/15/2021] [Indexed: 12/13/2022]
Abstract
The retinal pigment epithelium-photoreceptor interphase is renewed each day in a stunning display of cellular interdependence. While photoreceptors use photosensitive pigments to convert light into electrical signals, the RPE supports photoreceptors in their function by phagocytizing shed photoreceptor tips, regulating the blood retina barrier, and modulating inflammatory responses, as well as regenerating the 11-cis-retinal chromophore via the classical visual cycle. These processes involve multiple protein complexes, tightly regulated ligand-receptors interactions, and a plethora of lipids and protein-lipids interactions. The role of lipids in maintaining a healthy interplay between the RPE and photoreceptors has not been fully delineated. In recent years, novel technologies have resulted in major advancements in understanding several facets of this interplay, including the involvement of lipids in phagocytosis and phagolysosome function, nutrient recycling, and the metabolic dependence between the two cell types. In this review, we aim to integrate the complex role of lipids in photoreceptor and RPE function, emphasizing the dynamic exchange between the cells as well as discuss how these processes are affected in aging and retinal diseases.
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Affiliation(s)
- Dominik Lewandowski
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA
| | - Christopher L Sander
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA; Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Aleksander Tworak
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA
| | - Fangyuan Gao
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA
| | - Qianlan Xu
- Department of Physiology and Biophysics, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA; Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA
| | - Dorota Skowronska-Krawczyk
- Department of Physiology and Biophysics, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA; Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA.
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6
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Kim J, Lee YJ, Won JY. Molecular Mechanisms of Retinal Pigment Epithelium Dysfunction in Age-Related Macular Degeneration. Int J Mol Sci 2021; 22:ijms222212298. [PMID: 34830181 PMCID: PMC8624542 DOI: 10.3390/ijms222212298] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/12/2021] [Accepted: 11/12/2021] [Indexed: 02/06/2023] Open
Abstract
The retinal pigment epithelium (RPE), situated upon Bruch’s membrane, plays multiple roles in the ocular system by interacting with photoreceptors and. Therefore, dysfunction of the RPE causes diseases related to vision loss, such as age-related macular degeneration (AMD). Despite AMD being a global cause of blindness, the pathogenesis remains unclear. Understanding the pathogenesis of AMD is the first step for its prevention and treatment. This review summarizes the common pathways of RPE dysfunction and their effect in AMD. Potential treatment strategies for AMD based on targeting the RPE have also been discussed.
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Affiliation(s)
- Jongmin Kim
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea;
| | - Yeo Jin Lee
- Department of Ophthalmology and Visual Science, Eunpyeong St. Mary’s Hospital, The Catholic University of Korea, Seoul 03312, Korea;
- Catholic Institute for Visual Science, College of Medicine, The Catholic University of Korea, Seoul 14662, Korea
| | - Jae Yon Won
- Department of Ophthalmology and Visual Science, Eunpyeong St. Mary’s Hospital, The Catholic University of Korea, Seoul 03312, Korea;
- Catholic Institute for Visual Science, College of Medicine, The Catholic University of Korea, Seoul 14662, Korea
- Correspondence:
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7
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Tomita Y, Usui-Ouchi A, Nilsson AK, Yang J, Ko M, Hellström A, Fu Z. Metabolism in Retinopathy of Prematurity. Life (Basel) 2021; 11:life11111119. [PMID: 34832995 PMCID: PMC8620873 DOI: 10.3390/life11111119] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 10/11/2021] [Accepted: 10/19/2021] [Indexed: 12/12/2022] Open
Abstract
Retinopathy of prematurity is defined as retinal abnormalities that occur during development as a consequence of disturbed oxygen conditions and nutrient supply after preterm birth. Both neuronal maturation and retinal vascularization are impaired, leading to the compensatory but uncontrolled retinal neovessel growth. Current therapeutic interventions target the hypoxia-induced neovessels but negatively impact retinal neurons and normal vessels. Emerging evidence suggests that metabolic disturbance is a significant and underexplored risk factor in the disease pathogenesis. Hyperglycemia and dyslipidemia correlate with the retinal neurovascular dysfunction in infants born prematurely. Nutritional and hormonal supplementation relieve metabolic stress and improve retinal maturation. Here we focus on the mechanisms through which metabolism is involved in preterm-birth-related retinal disorder from clinical and experimental investigations. We will review and discuss potential therapeutic targets through the restoration of metabolic responses to prevent disease development and progression.
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Affiliation(s)
- Yohei Tomita
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (Y.T.); (J.Y.); (M.K.)
| | - Ayumi Usui-Ouchi
- Department of Ophthalmology, Juntendo University Urayasu Hospital, Chiba 279-0021, Japan;
| | - Anders K. Nilsson
- Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, 413 19 Gothenburg, Sweden; (A.K.N.); (A.H.)
| | - Jay Yang
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (Y.T.); (J.Y.); (M.K.)
| | - Minji Ko
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (Y.T.); (J.Y.); (M.K.)
| | - Ann Hellström
- Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, 413 19 Gothenburg, Sweden; (A.K.N.); (A.H.)
| | - Zhongjie Fu
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (Y.T.); (J.Y.); (M.K.)
- Correspondence:
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8
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Kwon W, Freeman SA. Phagocytosis by the Retinal Pigment Epithelium: Recognition, Resolution, Recycling. Front Immunol 2020; 11:604205. [PMID: 33281830 PMCID: PMC7691529 DOI: 10.3389/fimmu.2020.604205] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 10/20/2020] [Indexed: 12/13/2022] Open
Abstract
Tissue-resident phagocytes are responsible for the routine binding, engulfment, and resolution of their meals. Such populations of cells express appropriate surface receptors that are tailored to recognize the phagocytic targets of their niche and initiate the actin polymerization that drives internalization. Tissue-resident phagocytes also harbor enzymes and transporters along the endocytic pathway that orchestrate the resolution of ingested macromolecules from the phagolysosome. Solutes fluxed from the endocytic pathway and into the cytosol can then be reutilized by the phagocyte or exported for their use by neighboring cells. Such a fundamental metabolic coupling between resident phagocytes and the tissue in which they reside is well-emphasized in the case of retinal pigment epithelial (RPE) cells; specialized phagocytes that are responsible for the turnover of photoreceptor outer segments (POS). Photoreceptors are prone to photo-oxidative damage and their long-term health depends enormously on the disposal of aged portions of the outer segment. The phagocytosis of the POS by the RPE is the sole means of this turnover and clearance. RPE are themselves mitotically quiescent and therefore must resolve the ingested material to prevent their toxic accumulation in the lysosome that otherwise leads to retinal disorders. Here we describe the sequence of events underlying the healthy turnover of photoreceptors by the RPE with an emphasis on the signaling that ensures the phagocytosis of the distal POS and on the transport of solutes from the phagosome that supersedes its resolution. While other systems may utilize different receptors and transporters, the biophysical and metabolic manifestations of such events are expected to apply to all tissue-resident phagocytes that perform regular phagocytic programs.
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Affiliation(s)
- Whijin Kwon
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada
| | - Spencer A Freeman
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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9
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Eynard AR, Repossi G. Role of ω3 polyunsaturated fatty acids in diabetic retinopathy: a morphological and metabolically cross talk among blood retina barriers damage, autoimmunity and chronic inflammation. Lipids Health Dis 2019; 18:114. [PMID: 31092270 PMCID: PMC6521493 DOI: 10.1186/s12944-019-1049-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 04/12/2019] [Indexed: 12/11/2022] Open
Abstract
Vision disorders are one of the most serious complications of diabetes mellitus (DM) affecting the quality of life of patients and eventually cause blindness. The ocular lesions in diabetes mellitus are located mainly in the blood vessels and retina layers. Different retina lesions could be grouped under the umbrella term of diabetic retinopathies (DMRP). We propose that one of the main causes in the etiopathogenesis of the DMRP consists of a progressive loss of the selective permeability of blood retinal barriers (BRB). The loss of selective permeability of blood retinal barriers will cause a progressive autoimmune process. Prolonged autoimmune injures in the retinal territory will triggers and maintains a low-grade chronic inflammation process, microvascular alterations, glial proliferation and subsequent fibrosis and worse, progressive apoptosis of the photoreceptor neurons. Patients with long-standing DM disturbances in retinal BRBs suffer of alterations in the enzymatic pathways of polyunsaturated fatty acids (PUFAs), increase release of free radicals and pro-inflammatory molecules and subsequently incremented levels of vascular endothelial growth factor. These facts can produce retinal edema and photoreceptor apoptosis. Experimental, clinical and epidemiological evidences showing that adequate metabolic and alimentary controls and constant practices of healthy life may avoid, retard or make less severe the appearance of DMRP. Considering the high demand for PUFAs ω3 by photoreceptor complexes of the retina, it seems advisable to take fish oil supplements (2 g per day). The cellular, subcellular and molecular basis of the propositions exposed above is developed in this article. Synthesizer drawings the most relevant findings of the ultrastructural pathology, as well as the main metabolic pathways of the PUFAs involved in balance and disbalanced conditions are provided.
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Affiliation(s)
- Aldo R Eynard
- Instituto de Biología Celular, Histología y Embriología, Facultad de Ciencias Médicas, INICSA (CONICET-Universidad Nacional de Córdoba), Córdoba, Argentina.
| | - Gaston Repossi
- Instituto de Biología Celular, Histología y Embriología, Facultad de Ciencias Médicas, INICSA (CONICET-Universidad Nacional de Córdoba), Córdoba, Argentina.
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10
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Curcio CA. Soft Drusen in Age-Related Macular Degeneration: Biology and Targeting Via the Oil Spill Strategies. Invest Ophthalmol Vis Sci 2018; 59:AMD160-AMD181. [PMID: 30357336 PMCID: PMC6733535 DOI: 10.1167/iovs.18-24882] [Citation(s) in RCA: 173] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
AMD is a major cause of legal blindness in older adults approachable through multidisciplinary research involving human tissues and patients. AMD is a vascular-metabolic-inflammatory disease, in which two sets of extracellular deposits, soft drusen/basal linear deposit (BLinD) and subretinal drusenoid deposit (SDD), confer risk for end-stages of atrophy and neovascularization. Understanding how deposits form can lead to insights for new preventions and therapy. The topographic correspondence of BLinD and SDD with cones and rods, respectively, suggest newly realized exchange pathways among outer retinal cells and across Bruch's membrane and the subretinal space, in service of highly evolved, eye-specific physiology. This review focuses on soft drusen/BLinD, summarizing evidence that a major ultrastructural component is large apolipoprotein B,E-containing, cholesterol-rich lipoproteins secreted by the retinal pigment epithelium (RPE) that offload unneeded lipids of dietary and outer segment origin to create an atherosclerosis-like progression in the subRPE-basal lamina space. Clinical observations and an RPE cell culture system combine to suggest that soft drusen/BLinD form when secretions of functional RPE back up in the subRPE-basal lamina space by impaired egress across aged Bruch's membrane-choriocapillary endothelium. The soft drusen lifecycle includes growth, anterior migration of RPE atop drusen, then collapse, and atrophy. Proof-of-concept studies in humans and animal models suggest that targeting the “Oil Spill in Bruch's membrane” offers promise of treating a process in early AMD that underlies progression to both end-stages. A companion article addresses the antecedents of soft drusen within the biology of the macula.
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Affiliation(s)
- Christine A Curcio
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
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11
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Ao J, Wood JP, Chidlow G, Gillies MC, Casson RJ. Retinal pigment epithelium in the pathogenesis of age-related macular degeneration and photobiomodulation as a potential therapy? Clin Exp Ophthalmol 2018; 46:670-686. [PMID: 29205705 DOI: 10.1111/ceo.13121] [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: 09/11/2017] [Revised: 11/27/2017] [Accepted: 11/28/2017] [Indexed: 12/11/2022]
Abstract
The retinal pigment epithelium (RPE) comprises a monolayer of cells located between the neuroretina and the choriocapillaries. The RPE serves several important functions in the eye: formation of the blood-retinal barrier, protection of the retina from oxidative stress, nutrient delivery and waste disposal, ionic homeostasis, phagocytosis of photoreceptor outer segments, synthesis and release of growth factors, reisomerization of all-trans-retinal during the visual cycle, and establishment of ocular immune privilege. Age-related macular degeneration (AMD) is the leading cause of blindness in developed countries. Dysfunction of the RPE has been associated with the pathogenesis of AMD in relation to increased oxidative stress, mitochondrial destabilization and complement dysregulation. Photobiomodulation or near infrared light therapy which refers to non-invasive irradiation of tissue with light in the far-red to near-infrared light spectrum (630-1000 nm), is an intervention that specifically targets key mechanisms of RPE dysfunction that are implicated in AMD pathogenesis. The current evidence for the efficacy of photobiomodulation in AMD is poor but its safety profile and proposed mechanisms of action motivate further research as a novel therapy for AMD.
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Affiliation(s)
- Jack Ao
- South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, South Australia, Australia
| | - John Pm Wood
- South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, South Australia, Australia
| | - Glyn Chidlow
- South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, South Australia, Australia
| | - Mark C Gillies
- The Save Sight Institute, Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia
| | - Robert J Casson
- South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, South Australia, Australia
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12
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Gonzalez-Fernandez F, Fornalik M, Garlipp MA, Gonzalez-Fernandez P, Sung D, Meyer A, Baier R. Pericellular interphotoreceptor matrix dictates outer retina critical surface tension. Exp Eye Res 2017; 167:163-173. [PMID: 29051013 DOI: 10.1016/j.exer.2017.10.014] [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: 01/25/2017] [Revised: 07/30/2017] [Accepted: 10/12/2017] [Indexed: 11/15/2022]
Abstract
Retinal detachments create two pathological surfaces, the surface of the outer neural retinal, and an apical retinal-pigmented epithelium (RPE) surface. The physicochemical properties of these two new surfaces are poorly understood. At a molecular level little is known how detachments form, how to optimize reattachment, or prevent extension of the detachment. A major limitation is lack of information about the biophysical consequences of the retina-RPE separation. The primary challenge is determining the molecular properties of the pathological interface surfaces. Here, using detached bovine retina, we show that this hurdle can be overcome through a combination of biophysical and ultrastructural approaches. The outer surface of freshly detached bovine neural retina, and isolated molecular components of the outer retina were subjected to: 1) Contact angle goniometry to determine the critical surface tension of the outer retinal surface, isolated insoluble interphotoreceptor matrix (IPM) and purified interphotoreceptor retinoid binding protein (IRBP); 2) Multiple attenuated internal reflectance infrared (MAIR-IR) spectroscopy was used to characterize the molecular composition of the retinal surface. MAIR-IR depth penetration was established through ellipsometric measurement of barium-stearate films. Light microscopy, immunohistochemistry and electron microscopy defined the structures probed spectroscopically. Furthermore, the data were correlated to IR spectra of docosahexaenoic acid, hyaluronan, chondroitin-6-sulfate and IRBP, and imaging by IR-microscopy. We found that the retinal critical surface tension is 24 mN/m, similar to isolated insoluble IPM and lower than IRBP. Barium-stearate calibration studies established that the MAIR-IR spectroscopy penetration depth was 0.2 μm. Ultrastructural observations and MAIR-IR studies of isolated outer retina components determined that the pericellular IPM coating the outer retinal surface is primarily responsible for these surface properties. The critical surface tension of detached bovine retina is dictated not by the outer segments, but by a pericellular IPM covering the outer segment tips.
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Affiliation(s)
- Federico Gonzalez-Fernandez
- Medical Research Service, G.V. (Sonny) Montgomery Veterans Affairs Medical Center, Jackson, MS, United States; Ophthalmology and Pathology, University of Mississippi Medical Center, Jackson, MS, United States; Ophthalmology, Ross Eye Institute, SUNY, Buffalo, NY, United States; Pathology & Anatomic Sciences, SUNY, Buffalo, NY, United States.
| | - Mark Fornalik
- Center for Biosurfaces, SUNY, Buffalo, NY, United States
| | | | - Priscilla Gonzalez-Fernandez
- Medical Research Service, G.V. (Sonny) Montgomery Veterans Affairs Medical Center, Jackson, MS, United States; Ophthalmology, Ross Eye Institute, SUNY, Buffalo, NY, United States
| | - Dongjin Sung
- Ophthalmology, Ross Eye Institute, SUNY, Buffalo, NY, United States
| | - Anne Meyer
- Ophthalmology, Ross Eye Institute, SUNY, Buffalo, NY, United States; Center for Biosurfaces, SUNY, Buffalo, NY, United States
| | - Robert Baier
- Ophthalmology, Ross Eye Institute, SUNY, Buffalo, NY, United States; Center for Biosurfaces, SUNY, Buffalo, NY, United States
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Asatryan A, Bazan NG. Molecular mechanisms of signaling via the docosanoid neuroprotectin D1 for cellular homeostasis and neuroprotection. J Biol Chem 2017; 292:12390-12397. [PMID: 28615451 PMCID: PMC5535015 DOI: 10.1074/jbc.r117.783076] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Docosahexaenoic acid, enriched in the brain and retina, generates docosanoids in response to disruptions of cellular homeostasis. Docosanoids include neuroprotectin D1 (NPD1), which is decreased in the CA1 hippocampal area of patients with early-stage Alzheimer's disease (AD). We summarize here how NPD1 elicits neuroprotection by up-regulating c-REL, a nuclear factor (NF)-κB subtype that, in turn, enhances expression of BIRC3 (baculoviral inhibitor of apoptosis repeat-containing protein 3) in the retina and in experimental stroke, leading to neuroprotection. Elucidating the mechanisms of action of docosanoids will contribute to managing diseases, including stroke, AD, age-related macular degeneration, traumatic brain injury, Parkinson's disease, and other neurodegenerations.
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Affiliation(s)
- Aram Asatryan
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, Louisiana 70112-2223
| | - Nicolas G Bazan
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, Louisiana 70112-2223.
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14
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Zekavat SM, Lu J, Maugeais C, Mazer NA. An in silico model of retinal cholesterol dynamics (RCD model): insights into the pathophysiology of dry AMD. J Lipid Res 2017; 58:1325-1337. [PMID: 28442497 PMCID: PMC5496031 DOI: 10.1194/jlr.m074088] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 04/10/2017] [Indexed: 12/23/2022] Open
Abstract
We developed an in silico mathematical model of retinal cholesterol (Ch) dynamics (RCD) to quantify the physiological rate of Ch turnover in the rod outer segment (ROS), the lipoprotein transport mechanisms by which Ch enters and leaves the outer retina, and the rates of drusen growth and macrophage-mediated clearance in dry age-related macular degeneration. Based on existing experimental data and mechanistic hypotheses, we estimated the Ch turnover rate in the ROS to be 1–6 pg/mm2/min, dependent on the rate of Ch recycling in the outer retina, and found comparable rates for LDL receptor-mediated endocytosis of Ch by the retinal pigment epithelium (RPE), ABCA1-mediated Ch transport from the RPE to the outer retina, ABCA1-mediated Ch efflux from the RPE to the choroid, and the secretion of 70 nm ApoB-Ch particles from the RPE. The drusen growth rate is predicted to increase from 0.7 to 4.2 μm/year in proportion to the flux of ApoB-Ch particles. The rapid regression of drusen may be explained by macrophage-mediated clearance if the macrophage density reaches ∼3,500 cells/mm2. The RCD model quantifies retinal Ch dynamics and suggests that retinal Ch turnover and recycling, ApoB-Ch particle efflux, and macrophage-mediated clearance may explain the dynamics of drusen growth and regression.
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Affiliation(s)
| | - James Lu
- Departments of Clinical Pharmacology and Neuroscience, Ophthalmology, and
| | - Cyrille Maugeais
- Rare Diseases, Roche Innovation Center Basel, Basel, Switzerland
| | - Norman A Mazer
- Departments of Clinical Pharmacology and Neuroscience, Ophthalmology, and.
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15
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Yakubenko VP, Byzova TV. Biological and pathophysiological roles of end-products of DHA oxidation. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:407-415. [PMID: 27713004 DOI: 10.1016/j.bbalip.2016.09.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 09/28/2016] [Accepted: 09/29/2016] [Indexed: 01/20/2023]
Abstract
BACKGROUND Polyunsaturated fatty acids (PUFA) are known to be present and/or enriched in vegetable and fish oils. Among fatty acids, n-3 PUFA are generally considered to be protective in inflammation-related diseases. The guidelines for substituting saturated fatty acids for PUFAs have been highly publicized for decades by numerous health organizations. Recently, however, the beneficial properties of n-3 PUFA are questioned by detailed analyses of multiple randomized controlled clinical trials. The reported heterogeneity of results is likely due not only to differential effects of PUFAs on various pathological processes in humans, but also to the wide spectrum of PUFA's derived products generated in vivo. SCOPE OF REVIEW The goal of this review is to discuss the studies focused on well-defined end-products of PUFAs oxidation, their generation, presence in various pathological and physiological conditions, their biological activities and known receptors. Carboxyethylpyrrole (CEP), a DHA-derived oxidized product, is especially emphasized due to recent data demonstrating its pathophysiological significance in many inflammation-associated diseases, including atherosclerosis, hyperlipidemia, thrombosis, macular degeneration, and tumor progression. MAJOR CONCLUSIONS CEP is a product of radical-based oxidation of PUFA that forms adducts with proteins and lipids in blood and tissues, generating new powerful ligands for TLRs and scavenger receptors. The interaction of CEP with these receptors affects inflammatory response, angiogenesis, and wound healing. GENERAL SIGNIFICANCE The detailed understanding of CEP-mediated cellular responses may provide a basis for the development of novel therapeutic strategies and dietary recommendations.
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Affiliation(s)
- Valentin P Yakubenko
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States; Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
| | - Tatiana V Byzova
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States.
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Ghosh D, Haswell KM, Sprada M, Gonzalez-Fernandez F. Structure of zebrafish IRBP reveals fatty acid binding. Exp Eye Res 2015; 140:149-158. [PMID: 26344741 DOI: 10.1016/j.exer.2015.08.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Revised: 08/22/2015] [Accepted: 08/31/2015] [Indexed: 10/23/2022]
Abstract
Interphotoreceptor retinoid-binding protein (IRBP) has a remarkable role in targeting and protecting all-trans and 11-cis retinol, and 11-cis retinal during the rod and cone visual cycles. Little is known about how the correct retinoid is efficiently delivered and removed from the correct cell at the required time. It has been proposed that different fatty composition at that the outer-segments and retinal-pigmented epithelium have an important role is regulating the delivery and uptake of the visual cycle retinoids at the cell-interphotoreceptor-matrix interface. Although this suggests intriguing mechanisms for the role of local fatty acids in visual-cycle retinoid trafficking, nothing is known about the structural basis of IRBP-fatty acid interactions. Such regulation may be mediated through IRBP's unusual repeating homologous modules, each containing about 300 amino acids. We have been investigating structure-function relationships of Zebrafish IRBP (zIRBP), which has only two tandem modules (z1 and z2), as a model for the more complex four-module mammalian IRBP's. Here we report the first X-ray crystal structure of a teleost IRBP, and the only structure with a bound ligand. The X-ray structure of z1, determined at 1.90 Å resolution, reveals a two-domain organization of the module (domains A and B). A deep hydrophobic pocket with a single bound molecule of oleic acid was identified within the N-terminal domain A. In fluorescence titrations assays, oleic acid displaced all-trans retinol from zIRBP. Our study, which provides the first structure of an IRBP with bound ligand, supports a potential role for fatty acids in regulating retinoid binding.
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Affiliation(s)
- Debashis Ghosh
- Department of Pharmacology, State University of New York Upstate Medical University, Syracuse, NY, USA.
| | - Karen M Haswell
- Department of Pharmacology, State University of New York Upstate Medical University, Syracuse, NY, USA
| | - Molly Sprada
- SUNY Eye Institute, State University of New York, USA
| | - Federico Gonzalez-Fernandez
- Medical Research & Development Service, G.V. (Sonny) Veterans Affairs Medical Center, Jackson, MS, USA; Departments of Ophthalmology and Pathology, University of Mississippi Medical Center, Jackson, MS, USA; SUNY Eye Institute, State University of New York, USA.
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17
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Omega-3 Fatty Acids in Early Prevention of Inflammatory Neurodegenerative Disease: A Focus on Alzheimer's Disease. BIOMED RESEARCH INTERNATIONAL 2015; 2015:172801. [PMID: 26301243 PMCID: PMC4537710 DOI: 10.1155/2015/172801] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 02/23/2015] [Accepted: 02/23/2015] [Indexed: 11/17/2022]
Abstract
Alzheimer's disease (AD) is the leading cause of dementia and the most common neurodegenerative disease in the elderly. Furthermore, AD has provided the most positive indication to support the fact that inflammation contributes to neurodegenerative disease. The exact etiology of AD is unknown, but environmental and genetic factors are thought to contribute, such as advancing age, family history, presence of chronic diseases such as cardiovascular disease (CVD) and diabetes, and poor diet and lifestyle. It is hypothesised that early prevention or management of inflammation could delay the onset or reduce the symptoms of AD. Normal physiological changes to the brain with ageing include depletion of long chain omega-3 fatty acids and brains of AD patients have lower docosahexaenoic acid (DHA) levels. DHA supplementation can reduce markers of inflammation. This review specifically focusses on the evidence in humans from epidemiological, dietary intervention, and supplementation studies, which supports the role of long chain omega-3 fatty acids in the prevention or delay of cognitive decline in AD in its early stages. Longer term trials with long chain omega-3 supplementation in early stage AD are warranted. We also highlight the importance of overall quality and composition of the diet to protect against AD and dementia.
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Ramchani-Ben Othman K, Cercy C, Amri M, Doly M, Ranchon-Cole I. Dietary supplement enriched in antioxidants and omega-3 protects from progressive light-induced retinal degeneration. PLoS One 2015; 10:e0128395. [PMID: 26042773 PMCID: PMC4455991 DOI: 10.1371/journal.pone.0128395] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 04/27/2015] [Indexed: 11/30/2022] Open
Abstract
In the present study, we have evaluated one of the dietary supplements enriched with antioxidants and fish oil used in clinical care for patient with age-related macular degeneration. Rats were orally fed by a gastric canula daily with 0.2 ml of water or dietary supplement until they were sacrificed. After one week of treatment, animals were either sacrificed for lipid analysis in plasma and retina, or used for evaluation of rod-response recovery by electroretinography (ERG) followed by their sacrifice to measure rhodopsin content, or used for progressive light-induced retinal degeneration (PLIRD). For PLIRD, animals were transferred to bright cyclic light for one week. Retinal damage was quantified by ERG, histology and detection of apoptotic nuclei. Animals kept in dim-cyclic-light were processed in parallel. PLIRD induced a thinning of the outer nuclear layer and a reduction of the b-wave amplitude of the ERG in the water group. Retinal structure and function were preserved in supplemented animals. Supplement induced a significant increase in omega-3 fatty acids in plasma by 168% for eicosapentaenoic acid (EPA), 142% for docosapentaenoic acid (DPA) and 19% for docosahexaenoic acid (DHA) and a decrease in the omega-6 fatty acids, DPA by 28%. In the retina, supplement induced significant reduction of linolenic acid by 67% and an increase in EPA and DPA by 80% and 72%, respectively, associated with significant decrease in omega-6 DPA by 42%. Supplement did not affect rhodopsin content or rod-response recovery. The present data indicate that supplement rapidly modified the fatty acid content and induced an accumulation of EPA in the retina without affecting rhodopsin content or recovery. In addition, it protected the retina from oxidative stress induced by light. Therefore, this supplement might be beneficial to slow down progression of certain retinal degeneration.
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Affiliation(s)
- Khaoula Ramchani-Ben Othman
- Université Auvergne, UFR Pharmacie, Laboratoire de Biophysique Neurosensorielle, Inserm UMR 1107, Clermont-Ferrand, France
- Department of Biological Sciences, Tunis El Manar University, Laboratory of Functional Neurophysiology and Pathology, UR/11ES09, El Manar 1, Tunis, Tunisia
| | - Christine Cercy
- Université Auvergne, UFR Pharmacie, Laboratoire de Biophysique Neurosensorielle, Inserm UMR 1107, Clermont-Ferrand, France
| | - Mohamed Amri
- Department of Biological Sciences, Tunis El Manar University, Laboratory of Functional Neurophysiology and Pathology, UR/11ES09, El Manar 1, Tunis, Tunisia
| | - Michel Doly
- Université Auvergne, UFR Pharmacie, Laboratoire de Biophysique Neurosensorielle, Inserm UMR 1107, Clermont-Ferrand, France
| | - Isabelle Ranchon-Cole
- Université Auvergne, UFR Pharmacie, Laboratoire de Biophysique Neurosensorielle, Inserm UMR 1107, Clermont-Ferrand, France
- * E-mail:
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Cholesterol in the retina: the best is yet to come. Prog Retin Eye Res 2014; 41:64-89. [PMID: 24704580 DOI: 10.1016/j.preteyeres.2014.03.002] [Citation(s) in RCA: 191] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/13/2014] [Accepted: 03/17/2014] [Indexed: 01/09/2023]
Abstract
Historically understudied, cholesterol in the retina is receiving more attention now because of genetic studies showing that several cholesterol-related genes are risk factors for age-related macular degeneration (AMD) and because of eye pathology studies showing high cholesterol content of drusen, aging Bruch's membrane, and newly found subretinal lesions. The challenge before us is determining how the cholesterol-AMD link is realized. Meeting this challenge will require an excellent understanding these genes' roles in retinal physiology and how chorioretinal cholesterol is maintained. In the first half of this review, we will succinctly summarize physico-chemical properties of cholesterol, its distribution in the human body, general principles of maintenance and metabolism, and differences in cholesterol handling in human and mouse that impact on experimental approaches. This information will provide a backdrop to the second part of the review focusing on unique aspects of chorioretinal cholesterol homeostasis, aging in Bruch's membrane, cholesterol in AMD lesions, a model for lesion biogenesis, a model for macular vulnerability based on vascular biology, and alignment of AMD-related genes and pathobiology using cholesterol and an atherosclerosis-like progression as unifying features. We conclude with recommendations for the most important research steps we can take towards delineating the cholesterol-AMD link.
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Abstract
DHA is an abundant nutrient from marine lipids: its specific biological effects have been investigated in human volunteers, taking into consideration the dose effects. We report herein that, at dosages below 1 g/d, DHA proved to be effective in lowering blood platelet function and exhibited an 'antioxidant' effect. However, this was no longer the case following 1.6 g/d, showing then a U-shape response. The antioxidant effect has been observed in platelets as well as LDL, of which the redox status is assumed to be crucial in their relationship with atherosclerosis. Second, the oxygenated products of DHA, especially protectins produced by lipoxygenases, have been considered for their potential to affect blood platelets and leucocytes. It is concluded that DHA is an interesting nutrient to reduce atherothrombogenesis, possibly through complementary mechanisms involving lipoxygenase products of DHA.
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21
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Garlipp MA, Gonzalez-Fernandez F. Cone outer segment and Müller microvilli pericellular matrices provide binding domains for interphotoreceptor retinoid-binding protein (IRBP). Exp Eye Res 2013; 113:192-202. [DOI: 10.1016/j.exer.2013.02.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Revised: 01/24/2013] [Accepted: 02/04/2013] [Indexed: 10/27/2022]
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Stewart MW. Review of Aflibercept for the Treatment of Neovascular Age-Related Macular Degeneration. ACTA ACUST UNITED AC 2013. [DOI: 10.4137/cmt.s8921] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The treatment of exudative age-related macular degeneration (AMD) has been completely transformed by the development of drugs that bind vascular endothelial growth factor (VEGF). The antibody-based VEGF inhibitors bevacizumab and ranibizumab usually prevent the enlargement of choroidal neovascular membranes, reduce vascular permeability, and improve visual acuity. The newest VEGF inhibitor, aflibercept, is a soluble fusion protein that binds all isoforms of VEGF-A, VEGF-B, and placental growth factor with high affinity. Preclinical studies demonstrated aflibercept's ability to prevent experimental neovascularization and tumor growth in animal models. In phase 3 trials for exudative AMD, patients who received aflibercept avoided moderate vision loss and experienced improved visual acuity comparable to those who received ranibizumab. Additionally, patients who were treated with aflibercept 2 mg every 8 weeks (after 3 monthly loading doses) had similar visual results to those treated every 4 weeks. When treated as needed during the second year of the trials, patients were able to last an average of 3 months between aflibercept injections. Since its regulatory approval, aflibercept has also been found to perform well as a salvage therapy for eyes that respond incompletely to ranibizumab and bevacizumab. Because aflibercept can be administered less frequently than ranibizumab, it promises to decrease the frequency of patients’ visits to physicians’ offices in addition to the overall cost of AMD therapy.
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Role of ELOVL4 and very long-chain polyunsaturated fatty acids in mouse models of Stargardt type 3 retinal degeneration. Proc Natl Acad Sci U S A 2013; 110:5181-6. [PMID: 23479632 DOI: 10.1073/pnas.1214707110] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Stargardt type 3 (STGD3) disease is a juvenile macular dystrophy caused by mutations in the ELOVL4 (Elongation of very long chain fatty acids 4) gene. Its protein product, ELOVL4, is an elongase required for the biosynthesis of very long-chain polyunsaturated fatty acids (VLC-PUFAs). It is unclear whether photoreceptor degeneration in STGD3 is caused by loss of VLC-PUFAs or by mutated ELOVL4 protein trafficking/aggregation. We therefore generated conditional knockout (cKO) mice with Elovl4 ablated in rods or cones and compared their phenotypes to transgenic (TG) animals that express the human STGD3-causing ELOVL4(STGD3) allele. Gas chromatography-mass spectrometry was used to assess C30-C34 VLC-PUFA and N-retinylidene-N-retinylethanolamine content; electroretinography was used to measure phototransduction and outer retinal function; electron microscopy was used for retinal ultrastructure; and the optomotor tracking response was used to test scotopic and photopic visual performance. Elovl4 transcription and biosynthesis of C30-C34 VLC-PUFAs in rod cKO and TG retinas were reduced up to 98%, whereas the content of docosahexaenoic acid was diminished in TG, but not rod cKO, retinas. Despite the near-total loss of the retinal VLC-PUFA content, rod and cone cKO animals exhibited no electrophysiological or behavioral deficits, whereas the typical rod-cone dystrophic pattern was observed in TG animals. Our data suggest that photoreceptor-specific VLC-PUFA depletion is not sufficient to induce the STGD3 phenotype, because depletion alone had little effect on photoreceptor survival, phototransduction, synaptic transmission, and visual behavior.
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Curcio CA, Messinger JD, Sloan KR, McGwin G, Medeiros NE, Spaide RF. Subretinal drusenoid deposits in non-neovascular age-related macular degeneration: morphology, prevalence, topography, and biogenesis model. Retina 2013; 33:265-76. [PMID: 23266879 PMCID: PMC3870202 DOI: 10.1097/iae.0b013e31827e25e0] [Citation(s) in RCA: 293] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE To characterize the morphology, prevalence, and topography of subretinal drusenoid deposits, a candidate histological correlate of reticular pseudodrusen, with reference to basal linear deposit (BlinD), a specific lesion of age-related macular degeneration, and to propose a biogenesis model for both lesion. METHODS Donor eyes with median death-to-preservation of 2:40 hours were postfixed in osmium tannic acid paraphenylenediamine and prepared for macula-wide high-resolution digital sections. Annotated thicknesses of 21 chorioretinal layers were determined at standard locations in sections through the fovea and the superior perifovea. RESULTS In 22 eyes of 20 white donors (83.1 ± 7.7 years), SDD appeared as isolated or confluent drusenoid dollops punctuated by tufts of retinal pigment epithelium apical processes and associated with photoreceptor perturbation. Subretinal drusenoid deposits and BlinD were detected in 85 and 90% of non-neovascular age-related macular degeneration donors, respectively. Subretinal drusenoid deposit was thick (median, 9.4 μm) and more abundant in the perifovea than in the fovea (P < 0.0001). BlinD was thin (median, 2.1 μm) and more abundant in the fovea than in the perifovea (P < 0.0001). CONCLUSION Subretinal drusenoid deposits and BlinD prevalence in age-related macular degeneration eyes are high. Subretinal drusenoid deposits organized morphology, topography, and impact on surrounding photoreceptors imply specific processes of biogenesis. Contrasting topographies of subretinal drusenoid deposits and BlinD suggest relationships with differentiable aspects of rod and cone physiology, respectively. A 2-lesion 2-compartment biogenesis model incorporating outer retinal lipid homeostasis is presented.
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Affiliation(s)
- Christine A Curcio
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
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25
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Fredman G, Serhan CN. Specialized pro-resolving mediators: wiring the circuitry of effector immune and tissue homeostasis. ACTA ACUST UNITED AC 2012. [DOI: 10.1111/etp.12010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Mettu PS, Wielgus AR, Ong SS, Cousins SW. Retinal pigment epithelium response to oxidant injury in the pathogenesis of early age-related macular degeneration. Mol Aspects Med 2012; 33:376-98. [PMID: 22575354 DOI: 10.1016/j.mam.2012.04.006] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 04/14/2012] [Indexed: 01/06/2023]
Abstract
Age-related macular degeneration (AMD) represents the leading cause of vision loss in the elderly. Accumulation of lipid- and protein-rich deposits under the retinal pigment epithelium (RPE) heralds the onset of early AMD, but the pathogenesis of subretinal deposit formation is poorly understood. Numerous hypothetical models of deposit formation have been proposed, including hypotheses for a genetic basis, choroidal hypoperfusion, abnormal barrier formation, and lysosomal failure. This review explore the RPE injury hypothesis, characterized by three distinct stages (1) Initial RPE oxidant injury, caused by any number of endogenous or exogenous oxidants, results in extrusion of cell membrane "blebs," together with decreased activity of matrix metalloproteinases (MMPs), promoting bleb accumulation under the RPE as basal laminar deposits (BLD). (2) RPE cells are subsequently stimulated to increase synthesis of MMPs and other molecules responsible for extracellular matrix turnover (i.e., producing decreased collagen), affecting both RPE basement membrane and Bruchs membrane (BrM). This process leads to progression of BLD into basal linear deposits (BLinD) and drusen by admixture of blebs into BrM, followed by the formation of new basement membrane under the RPE to trap these deposits within BrM. We postulate that various hormones and other plasma-derived molecules related to systemic health cofactors are implicated in this second stage. (3) Finally, macrophages are recruited to sites of RPE injury and deposit formation. The recruitment of nonactivated or scavenging macrophages may remove deposits without further injury, while the recruitment of activated or reparative macrophages, through the release of inflammatory mediators, growth factors, or other substances, may promote complications and progression to the late forms of the disease.
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Affiliation(s)
- Priyatham S Mettu
- Duke Center for Macular Diseases, Duke Eye Center, Durham, NC 27710, USA
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Bazan NG, Molina MF, Gordon WC. Docosahexaenoic acid signalolipidomics in nutrition: significance in aging, neuroinflammation, macular degeneration, Alzheimer's, and other neurodegenerative diseases. Annu Rev Nutr 2011; 31:321-51. [PMID: 21756134 DOI: 10.1146/annurev.nutr.012809.104635] [Citation(s) in RCA: 302] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Essential polyunsaturated fatty acids (PUFAs) are critical nutritional lipids that must be obtained from the diet to sustain homeostasis. Omega-3 and -6 PUFAs are key components of biomembranes and play important roles in cell integrity, development, maintenance, and function. The essential omega-3 fatty acid family member docosahexaenoic acid (DHA) is avidly retained and uniquely concentrated in the nervous system, particularly in photoreceptors and synaptic membranes. DHA plays a key role in vision, neuroprotection, successful aging, memory, and other functions. In addition, DHA displays anti-inflammatory and inflammatory resolving properties in contrast to the proinflammatory actions of several members of the omega-6 PUFAs family. This review discusses DHA signalolipidomics, comprising the cellular/tissue organization of DHA uptake, its distribution among cellular compartments, the organization and function of membrane domains rich in DHA-containing phospholipids, and the cellular and molecular events revealed by the uncovering of signaling pathways regulated by DHA and docosanoids, the DHA-derived bioactive lipids, which include neuroprotectin D1 (NPD1), a novel DHA-derived stereoselective mediator. NPD1 synthesis agonists include neurotrophins and oxidative stress; NPD1 elicits potent anti-inflammatory actions and prohomeostatic bioactivity, is anti-angiogenic, promotes corneal nerve regeneration, and induces cell survival. In the context of DHA signalolipidomics, this review highlights aging and the evolving studies on the significance of DHA in Alzheimer's disease, macular degeneration, Parkinson's disease, and other brain disorders. DHA signalolipidomics in the nervous system offers emerging targets for pharmaceutical intervention and clinical translation.
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Affiliation(s)
- Nicolas G Bazan
- Neuroscience Center of Excellence and Department of Ophthalmology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA.
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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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Rodríguez IR, Larrayoz IM. Cholesterol oxidation in the retina: implications of 7KCh formation in chronic inflammation and age-related macular degeneration. J Lipid Res 2010; 51:2847-62. [PMID: 20567027 DOI: 10.1194/jlr.r004820] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
This review will discuss the formation and potential implications of 7-ketocholesterol (7KCh) in the retina. 7KCh is a proinflammatory oxysterol known to be present in high amounts in oxidized LDL deposits associated with atheromatous plaques. 7KCh is generated in situ in these lipoprotein deposits where it can accumulate and reach very high concentrations. In normal primate retina, 7KCh has been found associated with lipoprotein deposits in the choriocapillaris, Bruch's membrane, and the retinal pigment epithelium (RPE). In photodamaged rats, 7KCh has been found in the neural retina in areas of high mitochondrial content, ganglion cells, photoreceptor inner segments and synapses, and the RPE. Intermediates found by LCMS indicate 7KCh is formed via a free radical-mediated mechanism catalyzed by iron. 7KCh seems to activate several kinase signaling pathways that work via nuclear factor κB and cause the induction of vascular endothelial growth factor, interleukin (IL)-6, and IL-8. There seems to be little evidence of 7KCh metabolism in the retina, although some form of efflux mechanism may be active. The chronic mode of formation and the potent inflammatory properties of 7KCh indicate it may be an "age-related" risk factor in aging diseases such as atherosclerosis, Alzheimer's, and age-related macular degeneration.
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Affiliation(s)
- Ignacio R Rodríguez
- Mechanisms of Retinal Diseases Section, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, Bethesda, MD 20892, USA.
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The retinal pigment epithelium: something more than a constituent of the blood-retinal barrier--implications for the pathogenesis of diabetic retinopathy. J Biomed Biotechnol 2010; 2010:190724. [PMID: 20182540 PMCID: PMC2825554 DOI: 10.1155/2010/190724] [Citation(s) in RCA: 293] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Revised: 09/28/2009] [Accepted: 11/16/2009] [Indexed: 12/27/2022] Open
Abstract
The retinal pigment epithelium (RPE) is an specialized epithelium lying in the interface between the neural retina and the choriocapillaris where it forms the outer blood-retinal barrier (BRB). The main functions of the RPE are the following: (1) transport of nutrients, ions, and water, (2) absorption of light and protection against photooxidation, (3) reisomerization of all-trans-retinal into 11-cis-retinal, which is crucial for the visual cycle, (4) phagocytosis of shed photoreceptor membranes, and (5) secretion of essential factors for the structural integrity of the retina. An overview of these functions will be given. Most of the research on the physiopathology of diabetic retinopathy has been focused on the impairment of the neuroretina and the breakdown of the inner BRB. By contrast, the effects of diabetes on the RPE and in particular on its secretory activity have received less attention. In this regard, new therapeutic strategies addressed to modulating RPE impairment are warranted.
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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: 185] [Impact Index Per Article: 12.3] [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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Abstract
The evolution of light sensitive cells probably began with a primitive functional unit composed of a photoreceptor cell and a pigmented cell. Even during embryonic development this functional unit is formed in a differentiation process in which the two interacting partners depend on each other. For some of the most important forms of retinal degeneration this knowledge on the functional cooperation between retinal pigment epithelium and photoreceptors is of great importance for analysis and development of therapeutic approaches. In this way mutations of genes which are expressed in photoreceptors can lead to diseases which start in the retinal pigment epithelium and vice versa. This article summarizes the variety of different functions of the retinal pigment epithelium and describes the failure of those functions which are of most clinical importance.
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Wang L, Li CM, Rudolf M, Belyaeva OV, Chung BH, Messinger JD, Kedishvili NY, Curcio CA. Lipoprotein particles of intraocular origin in human Bruch membrane: an unusual lipid profile. Invest Ophthalmol Vis Sci 2008; 50:870-7. [PMID: 18806290 DOI: 10.1167/iovs.08-2376] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Throughout adulthood, Bruch membrane (BrM) accumulates esterified cholesterol (EC) associated with abundant 60- to 80-nm-diameter lipoprotein-like particles (LLP), putative apolipoprotein B (apoB) lipoproteins secreted by the retinal pigment epithelium (RPE). In the present study, neutral lipid, phospholipids, and retinoid components of human BrM-LLP were assayed. METHODS Particles isolated from paired choroids of human donors were subjected to comprehensive lipid profiling (preparative liquid chromatography [LC] gas chromatography [GC]), thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), Western blot analysis, and negative stain electron microscopy. Results were compared to plasma lipoproteins isolated from normolipemic volunteers and to conditioned medium from RPE-J cells supplemented with palmitate to induce particle synthesis and secretion. RESULTS EC was the largest component (32.4+/-7.9 mol%) of BrM-LLP lipids. EC was 11.3-fold more abundant than triglyceride (TG), unlike large apoB lipoproteins in plasma. Of the fatty acids (FA) esterified to cholesterol, linoleate (18:2n6) was the most abundant (41.7+/-4.7 mol%). Retinyl ester (RE) was detectable at picomolar levels in BrM-LLP. Notably scarce in any BrM-LLP lipid class was the photoreceptor-abundant FA docosahexaenoate (DHA, 22:6n3). RPE-J cells synthesized apoB and numerous EC-rich spherical particles. CONCLUSIONS BrM-LLP composition resembles plasma LDL more than it does photoreceptors. An EC-rich core is possible for newly synthesized lipoproteins as well as those processed in plasma. Abundant EC could contribute to a transport barrier in aging and lesion formation in age-related maculopathy (ARM). Analysis of BrM-LLP composition has revealed new aspects of retinal cholesterol and retinoid homeostasis.
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Affiliation(s)
- Lan Wang
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama 35294-0009, USA
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Katzen-Luchenta J. The declaration of nutrition, health, and intelligence for the child-to-be. Nutr Health 2008; 19:85-102. [PMID: 18309769 DOI: 10.1177/026010600701900212] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The Declaration of Nutrition, Health, and Intelligence for the Child-to-be is an urgent cry from the unborn child for a life-span of nutrients for physical and mental wellness. It is a proclamation of paramount importance for everyone involved in child development: parents, health professionals, teachers, government agencies, all producers of food--and children, so they may learn how to feed themselves well. The Declaration of Olympia on Nutrition and Fitness, 1996, came from a group pf nutritional scientists and medical doctors to commemorate the Olympic Games' 100th anniversary. They based it on the health principles of Hippocrates: genetics, the age of the individual, the powers of various foods, and exercise. Following today's vast wealth of nutritional research and expressing it with my teaching experience, I have revitalized the Declaration of Olympia by writing from the heart of the little learner and the hope of the child-to-be. The nutrients implicated in healthy reproduction and lifelong health include B vitamins, particularly B1, B6, folate, B1312 antioxidants, particularly vitamins C and E: minerals such as iron, zinc, magnesium, selenium, iodine, and copper; and essential fatty acids, particularly DHA. These nutrients also lower the risk of neural tube defects: autism, dyslexia, Down's syndrome: childhood cancers, obesity, and defective fetal cell membranes associated with maternal diabetes. Our metabolism is hugely influenced also by activity and by affection. Today's foods are often processed beyond the cells' recognition and can result in neurological and physical morbidity and mortality. A diet of unprocessed free-range animals and seafood: legumes, deep-colored vegetables and fruits: nuts, seeds, and whole grains, germ and bran, reinstates nutritional potency.
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Ford DA, Monda JK, Brush RS, Anderson RE, Richards MJ, Fliesler SJ. Lipidomic analysis of the retina in a rat model of Smith-Lemli-Opitz syndrome: alterations in docosahexaenoic acid content of phospholipid molecular species. J Neurochem 2007; 105:1032-47. [PMID: 18182048 DOI: 10.1111/j.1471-4159.2007.05203.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Smith-Lemli-Opitz syndrome (SLOS) is a complex hereditary disease caused by an enzymatic defect in the last step of cholesterol biosynthesis. Progressive retinal degeneration occurs in an AY9944-induced rat model of SLOS, with biochemical and electroretinographic hallmarks comparable with the human disease. We evaluated alterations in the non-sterol lipid components of the retina in this model, compared with age-matched controls, using lipidomic analysis. The levels of 16:0-22:6 and 18:0-22:6 phosphatidylcholine molecular species in retinas were less by > 50% and > 33%, respectively, in rats treated for either 2 or 3 months with AY9944. Relative to controls, AY9944 treatment resulted in > 60% less di-22:6 and > 15% less 18:0-22:6 phosphatidylethanolamine molecular species. The predominant phosphatidylserine (PS) molecular species in control retinas were 18:0-22:6 and di-22:6; notably, AY9944 treatment resulted in > 80% less di-22:6 PS, relative to controls. Remarkably, these changes occurred in the absence of n3 fatty acid deficiency in plasma or liver. Thus, the retinal lipidome is globally altered in the SLOS rat model, relative to control rats, with the most profound changes being less phosphatidylcholine, phosphatidylethanolamine, and PS molecular species containing docosahexaenoic acid (22:6). These findings suggest that SLOS may involve additional metabolic compromise beyond the primary enzymatic defect in the cholesterol pathway.
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Affiliation(s)
- David A Ford
- E. A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, USA
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Haubner L, Sullivan J, Ashmeade T, Saste M, Wiener D, Carver J. The effects of maternal dietary docosahexaenoic acid intake on rat pup myelin and the auditory startle response. Dev Neurosci 2007; 29:460-7. [PMID: 17684314 DOI: 10.1159/000107047] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Accepted: 01/12/2007] [Indexed: 11/19/2022] Open
Abstract
UNLABELLED We investigated the effects of maternal docosahexanoic acid (DHA) supplementation on pups' auditory startle responses and the composition of brain myelin. METHODS Timed-pregnant rats were fed throughout pregnancy and lactation diets that contained 0, 0.3, 0.7 or 3% of total fatty acids as DHA. Milk was collected from culled pups' stomachs on postnatal day (PND) 3, latency of the auditory startle reflex was measured on PND 15, and pups were killed and brains collected on PND 24. RESULTS Higher levels of DHA in maternal diet were reflected in milk and in pups' myelin. The latency of the auditory startle response was significantly longer in offspring of dams fed higher levels of DHA. There was a positive correlation between the myelin content of DHA and the latency of the startle response (p = 0.044), and a negative correlation between the myelin content of DHA and the myelin content of cholesterol (p = 0.005). CONCLUSION High levels of maternal DHA intake alter the lipid composition of rat pup myelin, and are associated with longer latencies of the auditory startle response--a myelin-dependent electrophysiologic response.
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Affiliation(s)
- Laura Haubner
- Department of Pediatrics, University of South Florida College of Medicine, Tampa, Fla, USA.
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Qin S. Oxidative damage of retinal pigment epithelial cells and age-related macular degeneration. Drug Dev Res 2007. [DOI: 10.1002/ddr.20185] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Langelier B, Alessandri JM, Perruchot MH, Guesnet P, Lavialle M. Changes of the transcriptional and fatty acid profiles in response to n-3 fatty acids in SH-SY5Y neuroblastoma cells. Lipids 2006; 40:719-28. [PMID: 16196423 DOI: 10.1007/s11745-005-1435-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Synthesis of docosahexaenoic acid (DHA) from its metabolic precursors contributes to membrane incorporation of this FA within the central nervous system. Although cultured neural cells are able to produce DHA, the membrane DHA contents resulting from metabolic conversion do not match the high values of those resulting from supplementation with preformed DHA. We have examined whether the DHA precursors down-regulate the incorporation of newly formed DHA within human neuroblastoma cells. SH-SY5Y cells were incubated with gradual doses of alpha-linolenic acid (alpha-LNA), EPA, or docosapentaenoic acid (DPA), and the incorporation of DHA into ethanolamine glycerophospholipids was analyzed as a reflection of synthesizing activity. The incorporation of EPA, DPA, and preformed DHA followed a dose-response saturating curve, whereas that of DHA synthesized either from alpha-LNA, EPA, or DPA peaked at concentrations of precursors below 15-30 microM and sharply decreased with higher doses. The mRNA encoding for six FA metabolism genes were quantified using real-time PCR. Two enzymes of the peroxisomal beta-oxidation, L-bifunctional protein and peroxisomal acyl-CoA oxidase, were expressed at lower levels than fatty acyl-CoA ligase 3 (FACL3) and delta6-desaturase (delta6-D). The delta6-D mRNA slightly increased between 16 and 48 h of culture, and this effect was abolished in the presence of 70 microM EPA. In contrast, the EPA treatment resulted in a time-dependent increase of FACL3 mRNA. The terminal step of DHA synthesis seems to form a "metabolic bottleneck," resulting in accretion of EPA and DPA when the precursor concentration exceeds a specific threshold value. We conclude that the critical precursor- concentration window of responsiveness may originate from the low basal expression level of peroxisomal enzymes.
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Affiliation(s)
- Bénédicte Langelier
- Nutrition & Food Safety, Neurobiology of Lipids, INRA (l'Institut National de la Recherche Agronomique), Jouy-en-Josas, France
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Molecular and Cellular Regulation of Pineal Organ Responses. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/s1546-5098(06)25006-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Li CM, Presley JB, Zhang X, Dashti N, Chung BH, Medeiros NE, Guidry C, Curcio CA. Retina expresses microsomal triglyceride transfer protein: implications for age-related maculopathy. J Lipid Res 2005; 46:628-40. [PMID: 15654125 DOI: 10.1194/jlr.m400428-jlr200] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The principal extracellular lesions of age-related maculopathy (ARM), the leading cause of vision loss in the elderly, involve Bruch's membrane (BrM), a thin vascular intima between the retinal pigment epithelium (RPE) and its blood supply. With age, 80-100 nm solid particles containing esterified cholesterol (EC) accumulate in normal BrM, and apolipoprotein B (apoB) immunoreactivity is detectable in BrM- and ARM-associated lesions. Yet little evidence indicates that increased plasma cholesterol is a risk factor for ARM. To determine if RPE is capable of assembling its own apoB-containing lipoprotein, we examined RPE for the expression of microsomal triglyceride transfer protein (MTP), which is required for this process. Consistent with previous evidence for apoB expression, MTP is expressed in RPE, the ARPE-19 cell line, and, unexpectedly, retinal ganglion cells, which are neurons of the central nervous system. De novo synthesis and secretion of neutral lipid by ARPE-19 was supported by high levels of radiolabeled EC and triglyceride in medium after supplementation with oleate. Lipoprotein assembly and secretion is implicated as a constitutive retinal function and a plausible candidate mechanism involved in forming extracellular cholesterol-containing lesions in ARM. The pigmentary retinopathy and neuropathy of abetalipoproteinemia (Mendelian Inheritance of Man 200100; Bassen-Kornzwieg disease), which is caused by mutations in the MTP gene, may involve loss of function at the retina.
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Affiliation(s)
- Chuan-Ming Li
- Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, AL, USA
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Alessandri JM, Poumès-Ballihaut C, Langelier B, Perruchot MH, Raguénez G, Lavialle M, Guesnet P. Incorporation of docosahexaenoic acid into nerve membrane phospholipids: bridging the gap between animals and cultured cells. Am J Clin Nutr 2003; 78:702-10. [PMID: 14522727 DOI: 10.1093/ajcn/78.4.702] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Functional maturation of nervous tissues depends on membrane accretion of docosahexaenoic acid (DHA). Animal studies have shown that incorporation of dietary DHA into membrane phospholipids is dose dependent. The molecular effects of DHA are commonly studied in cultured cells, but questions remain about the physiologic connection between animal and cell models. OBJECTIVE We developed a linear model for comparing the responses of rat nervous tissues to dietary DHA with the responses of human cell lines to DHA in medium. DESIGN Rats were rendered chronically deficient in n-3 fatty acids by being reared on a peanut oil diet. DHA status was replenished in the F2 generation by using increasing supplements of a microalgal oil. Human retinoblastoma and neuroblastoma cells were dosed with unesterified DHA. DHA accumulation into phospholipids was defined by the plateau of the dose-response curve (DHA(max)) and by the supplement required to produce one-half the DHA(max) (DHA(50)). RESULTS The DHA(max) values for 4 brain regions and 2 neuroblastoma lines were similar, and the value for the retinoblastoma line was similar to the retinal value. Expressing the DHA input as micro mol/10 g diet and as micro mol/L medium resulted in similar values for the ratio of DHA(max) to DHA(50) in the 4 brain regions and the 3 cell lines. The DHA(max)-DHA(50) ratios in the ethanolamine phosphoglyceride and phosphatidylcholine fractions in retinal phospholipids were 6 and 10 times, respectively, those in the brain and cultured cells. CONCLUSIONS The dose-dependent responses of cells and the brain to DHA supplements can be compared by using DHA(max)-DHA(50) ratios. We propose a counting frame that allows the comparison of the dose responses of the brain and cells to exogenous DHA.
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Affiliation(s)
- Jean-Marc Alessandri
- Nutrition & Food Safety Laboratory, Neurobiology of Lipids, Institut National de la Recherche Agronomique, Jouy-en-Josas, France.
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Jeffrey BG, Mitchell DC, Hibbeln JR, Gibson RA, Chedester AL, Salem N. Visual acuity and retinal function in infant monkeys fed long-chain PUFA. Lipids 2002; 37:839-48. [PMID: 12458618 DOI: 10.1007/s11745-002-0969-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Previous randomized clinical trials suggest that supplementation of the human infant diet with up to 0.35% DHA may benefit visual development. The aim of the current study was to assess the impact of including arachidonic acid (AA) and a higher level of DHA in the postnatal monkey diet on visual development. Infant rhesus monkeys were fed either a control diet (2.0% alpha-linolenic acid as the sole n-3 FA) or a supplemented diet (1.0% DHA and 1.0% AA) from birth. Visual evoked potential acuity was measured at 3 mon of age. Rod and cone function were assessed in terms of parameters describing phototransduction. Electroretinogram (ERG) amplitudes and implicit times were recorded over a wide intensity range (-2.2 to 4.0 log scot td-sec) and assessed in terms of intensity response functions. Plasma DHA and AA were significantly increased (P < 0.001) in the diet-supplemented monkeys compared with the control monkeys. There was an approximately equal effect of diet for the rod phototransduction parameters, sensitivity, and capacitance but in the opposite directions. Diet-supplemented monkeys had significantly shorter b-wave implicit times at low retinal illuminances (<-0.6 log scot td-sec). There were no significant effects of diet for visual acuity or the other 23 ERG parameters measured. The results suggest that supplementation of the infant monkey diet with 1.0% DHA and 1.0% AA neither harms nor provides substantial benefit to the development of visual acuity or retinal function in the first four postnatal months.
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Affiliation(s)
- Brett G Jeffrey
- Department of Paediatrics and Child Health, Flinders Medical Centre, The Flinders University of South Australia, Bedford Park, Adelaide, SA 5042, Australia
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Dunbar BL, Bauer JE. Metabolism of dietary essential fatty acids and their conversion to long-chain polyunsaturated metabolites. J Am Vet Med Assoc 2002; 220:1621-6. [PMID: 12051499 DOI: 10.2460/javma.2002.220.1621] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Brent L Dunbar
- Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station 77843-4474, USA
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Abstract
An important role for docosahexaenoic acid (DHA) within the retina is suggested by its high levels and active conservation in this tissue. Animals raised on n-3-deficient diets have large reductions in retinal DHA levels that are associated with altered retinal function as assessed by the electroretinogram (ERG). Despite two decades of research in this field, little is known about the mechanisms underlying altered retinal function in n-3-deficient animals. The focus of this review is on recent research that has sought to elucidate the role of DHA in retinal function, particularly within the rod photoreceptor outer segments where DHA is found at its highest concentration. An overview is also given of human infant studies that have examined whether a neonatal dietary supply of DHA is required for the normal development of retinal function.
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Affiliation(s)
- B G Jeffrey
- Department of Paediatrics and Child Health, Flinders Medical Centre, The Flinders University of South Australia, Bedford Park, Adelaide, South Australia 5042, Australia
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46
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Themsche CV, Jacob M, Salesse C. Human retinal pigment epithelium secretes a phospholipase A2 and contains two novel intracellular phospholipases A2. Biochem Cell Biol 2001. [DOI: 10.1139/o00-088] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The sensitivity of different phospholipase A2 (PLA2)-active fractions eluted from cation-exchange chromatography to para-bromophenacylbromide (pBPB), Ca2+-EGTA, DTT, heat, and H2SO4 indicates that human cultured retinal pigment epithelial (hRPE) cells probably contain two different intracellular PLA2 enzymes. Control experiments using "back-and-forth" thin-layer chromatography confirmed that, in our assay conditions, the generation of free fatty acids originated solely from PLA2 activity. Together with immunoblot experiments where no cross-reactivity was observed between the hRPE cytosolic PLA2 enzymes and several antisera directed against secretory PLA2s (sPLA2s) and cytosolic PLA2 (cPLA2), these findings suggest that intracellular hRPE PLA2s are different from well-known sPLA2s, cPLA2, and Ca2+-independent PLA2s. We also report an additional hRPE-PLA2 enzyme that is secreted and that exhibits sensitivity to pBPB, Ca2+-EGTA, DTT, heat, and H2SO4, which is characteristic of sPLA2 enzymes. This approximately 22-kDa PLA2 cross-reacted weakly with an antiserum directed against porcine pancreatic group I sPLA2 but strongly with an antiserum directed against N-terminal residues 1-14 of human synovial group II sPLA2, suggesting that this extracellular enzyme is a member of the sPLA2 class of enzymes. We thus conclude that there are three distinct PLA2 enzymes in cultured hRPE cells, including two novel intracellular PLA2s and a 22-kDa secreted sPLA2 enzyme.Key words: phospholipase A2, retinal pigment epithelium, characterization.
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47
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Giusto NM, Pasquaré SJ, Salvador GA, Castagnet PI, Roque ME, Ilincheta de Boschero MG. Lipid metabolism in vertebrate retinal rod outer segments. Prog Lipid Res 2000; 39:315-91. [PMID: 10856601 DOI: 10.1016/s0163-7827(00)00009-6] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- N M Giusto
- Instituto de Investigaciones Bioquímicas, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas, CC 857, B 8000 FWB, Bahia Blanca, Argentina.
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48
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Stief TW. The blood fibrinolysis/deep-sea analogy: a hypothesis on the cell signals singlet oxygen/photons as natural antithrombotics. Thromb Res 2000; 99:1-20. [PMID: 10904099 DOI: 10.1016/s0049-3848(00)00213-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- T W Stief
- Institute of Clinical Chemistry and Molecular Diagnostics, Philipps University, Marburg, Germany.
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Goustard-Langelier B, Alessandri JM, Raguenez G, Durand G, Courtois Y. Phospholipid incorporation and metabolic conversion of n-3 polyunsaturated fatty acids in the Y79 retinoblastoma cell line. J Neurosci Res 2000; 60:678-85. [PMID: 10820439 DOI: 10.1002/(sici)1097-4547(20000601)60:5<678::aid-jnr13>3.0.co;2-t] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The metabolic conversion of n-3 fatty acids was studied in the human Y79 retinoblastoma cell line. Cultured cells were exposed to increasing concentrations of either 18:3n-3, 22:5n-3, or 22:6n-3, and their phospholipid fatty acid composition was analyzed after 72 hr. Cells internalized the supplemental fatty acids and proceeded to their metabolic conversion. Supplemental 22:6n-3 was directly esterified into cell phospholipids, at levels typical for normal neural retinas (41% by weight of phosphatidylethanolamine fatty acids, and 24% of phosphatidylcholine fatty acids). In contrast, 18:3n-3 was mainly converted to 20:5n-3 and 22:5n-3, both of which appeared in cell phospholipids after exposure to low external concentrations of 18:3n-3 (10 microg/ml). Y79 cells can proceed to the metabolic conversion of 18:3n-3 through elongation and Delta6- and Delta5-desaturation. When cells were exposed to high external concentrations of 18:3n-3 (30 microg/ml), the supplemental fatty acid was directly incorporated, and its relative content increased in both phospholipid classes to the detriment of all other n-3 fatty acids. Cells cultured in the presence of 22:5n-3 did not incorporate 22:6n-3 into their phospholipids but did incorporate 20:5n-3 and 22:5n-3. The data suggest that Y79 cells can proceed to the microsomal steps of n-3 metabolism, involving elongation, desaturation, and chain shortening of 22C fatty acids. Although Y79 cells avidly used supplemental 22:6n-3 for phospholipid incorporation at levels typical for normal photoreceptor cells, they failed to match such levels through metabolic conversion of n-3 parent fatty acids. The terminal step of the very long-chain polyunsaturated fatty acid synthesis, consisting in Delta6-desaturation followed by peroxisomal chain shortening of 24C-fatty acids, could be rate-limiting in Y79 cells.
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Affiliation(s)
- B Goustard-Langelier
- Institut National de la Recherche Agronomique, Laboratoire de Nutrition et Sécurité Alimentaire, Jouy-en-Josas, France
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50
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Abstract
Phagocytosis of tips of rod outer segments (ROS) by retinal pigment epithelial (RPE) cells is vitally important for maintaining structural and functional integrity of the retina. We previously reported that receptor-mediated specific phagocytosis of ROS induces expression of early response genes coding for transcription factors. Here we study the expression of peroxisome proliferator-activated receptors (PPAR) -alpha, -delta (beta) and -gamma during ROS phagocytosis of rat RPE cells in primary cell culture, using competitive quantitative RT-PCR. During phagocytosis of ROS (but not of latex particles) by RPE cells, RT-PCR revealed a transient increase in PPARgamma mRNA expression, that peaked at 4-6 hr. We sequenced and described two alternatively spliced variants of rat PPARgamma: rPPARgamma1a and rPPARgamma1b. Both of these, along with the recently described rPPARgamma2 were induced by ROS phagocytosis. PPARalpha and PPARdelta mRNA expression was also detected in RPE cells, but the level of expression did not change during ROS phagocytosis. All-trans-retinoic acid and prostaglandin E(2) (PGE(2)) selectively potentiated both basal and ROS-phagocytosis-induced PPARgamma expression. All-trans-retinoic acid had the opposite inhibitory effect on PPARalpha and PPARdelta expression. Cycloheximide had a dual action on PPARgamma expression in RPE cells: it enhanced expression under basal conditions but repressed expression induced by ROS phagocytosis. It also stimulated expression of PPARalpha but had no effect on PPARdelta. Selective activation of PPARgamma may play an important role in regulating the expression of target genes that are involved in lipid and fatty acid metabolism in the photoreceptor renewal process.
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Affiliation(s)
- A V Ershov
- Neuroscience Center of Excellence and Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans. LA, USA
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