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Andreazzoli M, Longoni B, Angeloni D, Demontis GC. Retinoid Synthesis Regulation by Retinal Cells in Health and Disease. Cells 2024; 13:871. [PMID: 38786093 PMCID: PMC11120330 DOI: 10.3390/cells13100871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 05/13/2024] [Accepted: 05/13/2024] [Indexed: 05/25/2024] Open
Abstract
Vision starts in retinal photoreceptors when specialized proteins (opsins) sense photons via their covalently bonded vitamin A derivative 11cis retinaldehyde (11cis-RAL). The reaction of non-enzymatic aldehydes with amino groups lacks specificity, and the reaction products may trigger cell damage. However, the reduced synthesis of 11cis-RAL results in photoreceptor demise and suggests the need for careful control over 11cis-RAL handling by retinal cells. This perspective focuses on retinoid(s) synthesis, their control in the adult retina, and their role during retina development. It also explores the potential importance of 9cis vitamin A derivatives in regulating retinoid synthesis and their impact on photoreceptor development and survival. Additionally, recent advancements suggesting the pivotal nature of retinoid synthesis regulation for cone cell viability are discussed.
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Affiliation(s)
| | - Biancamaria Longoni
- Department of Translational Medicine and New Technologies in Medicine, University of Pisa, 56126 Pisa, Italy
| | - Debora Angeloni
- The Institute of Biorobotics, Scuola Superiore Sant’Anna, 56127 Pisa, Italy
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2
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Basyal D, Lee S, Kim HJ. Antioxidants and Mechanistic Insights for Managing Dry Age-Related Macular Degeneration. Antioxidants (Basel) 2024; 13:568. [PMID: 38790673 PMCID: PMC11117704 DOI: 10.3390/antiox13050568] [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: 03/18/2024] [Revised: 04/26/2024] [Accepted: 05/02/2024] [Indexed: 05/26/2024] Open
Abstract
Age-related macular degeneration (AMD) severely affects central vision due to progressive macular degeneration and its staggering prevalence is rising globally, especially in the elderly population above 55 years. Increased oxidative stress with aging is considered an important contributor to AMD pathogenesis despite multifaceted risk factors including genetic predisposition and environmental agents. Wet AMD can be managed with routine intra-vitreal injection of angiogenesis inhibitors, but no satisfactory medicine has been approved for the successful management of the dry form. The toxic carbonyls due to photo-oxidative degradation of accumulated bisretinoids within lysosomes initiate a series of events including protein adduct formation, impaired autophagy flux, complement activation, and chronic inflammation, which is implicated in dry AMD. Therapy based on antioxidants has been extensively studied for its promising effect in reducing the impact of oxidative stress. This paper reviews the dry AMD pathogenesis, delineates the effectiveness of dietary and nutrition supplements in clinical studies, and explores pre-clinical studies of antioxidant molecules, extracts, and formulations with their mechanistic insights.
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Affiliation(s)
| | | | - Hye Jin Kim
- College of Pharmacy, Keimyung University, Dauge 42601, Republic of Korea
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3
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Dontsov A, Ostrovsky M. Retinal Pigment Epithelium Pigment Granules: Norms, Age Relations and Pathology. Int J Mol Sci 2024; 25:3609. [PMID: 38612421 PMCID: PMC11011557 DOI: 10.3390/ijms25073609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 03/20/2024] [Accepted: 03/21/2024] [Indexed: 04/14/2024] Open
Abstract
The retinal pigment epithelium (RPE), which ensures the normal functioning of the neural retina, is a pigmented single-cell layer that separates the retina from the Bruch's membrane and the choroid. There are three main types of pigment granules in the RPE cells of the human eye: lipofuscin granules (LG) containing the fluorescent "age pigment" lipofuscin, melanoprotein granules (melanosomes, melanolysosomes) containing the screening pigment melanin and complex melanolipofuscin granules (MLG) containing both types of pigments simultaneously-melanin and lipofuscin. This review examines the functional role of pigment granules in the aging process and in the development of oxidative stress and associated pathologies in RPE cells. The focus is on the process of light-induced oxidative degradation of pigment granules caused by reactive oxygen species. The reasons leading to increased oxidative stress in RPE cells as a result of the oxidative degradation of pigment granules are considered. A mechanism is proposed to explain the phenomenon of age-related decline in melanin content in RPE cells. The essence of the mechanism is that when the lipofuscin part of the melanolipofuscin granule is exposed to light, reactive oxygen species are formed, which destroy the melanin part. As more melanolipofuscin granules are formed with age and the development of degenerative diseases, the melanin in pigmented epithelial cells ultimately disappears.
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Affiliation(s)
| | - Mikhail Ostrovsky
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow 119334, Russia;
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4
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Lains I, Han X, Gil J, Providencia J, Nigalye A, Alvarez R, Douglas VP, Mendez K, Katz R, Tsougranis G, Li J, Kelly RS, Kim IK, Lasky-Su J, Silva R, Miller JW, Liang L, Vavvas D, Miller JB, Husain D. Plasma Metabolites Associated with OCT Features of Age-Related Macular Degeneration. OPHTHALMOLOGY SCIENCE 2024; 4:100357. [PMID: 37869026 PMCID: PMC10587636 DOI: 10.1016/j.xops.2023.100357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 05/13/2023] [Accepted: 06/06/2023] [Indexed: 10/24/2023]
Abstract
Purpose The most widely used classifications of age-related macular degeneration (AMD) and its severity stages still rely on color fundus photographs (CFPs). However, AMD has a wide phenotypic variability that remains poorly understood and is better characterized by OCT. We and others have shown that patients with AMD have a distinct plasma metabolomic profile compared with controls. However, all studies to date have been performed solely based on CFP classifications. This study aimed to assess if plasma metabolomic profiles are associated with OCT features commonly seen in AMD. Design Prospectively designed, cross-sectional study. Participants Subjects with a diagnosis of AMD and a control group (> 50 years old) from Boston, United States, and Coimbra, Portugal. Methods All participants were imaged with CFP, used for AMD staging (Age-Related Eye Disease Study 2 classification scheme), and with spectral domain OCT (Spectralis, Heidelberg). OCT images were graded by 2 independent graders for the presence of characteristic AMD features, according to a predefined protocol. Fasting blood samples were collected for metabolomic profiling (using nontargeted high-resolution mass spectrometry by Metabolon Inc). Analyses were conducted using logistic regression models including the worst eye of each patient (AREDS2 classification) and adjusting for confounding factors. Each cohort (United States and Portugal) was analyzed separately and then results were combined by meta-analyses. False discovery rate (FDR) was used to account for multiple comparisons. Main Outcome Measures Plasma metabolite levels associated with OCT features. Results We included data on 468 patients, 374 with AMD and 94 controls, and on 725 named endogenous metabolites. Meta-analysis identified significant associations (FDR < 0.05) between plasma metabolites and 3 OCT features: hyperreflective foci (6), atrophy (6), and ellipsoid zone disruption (3). Most associations were seen with amino acids, and all but 1 metabolite presented specific associations with the OCT features assessed. Conclusions To our knowledge, we show for the first time that plasma metabolites have associations with specific OCT features seen in AMD. Our results support that the wide spectrum of presentations of AMD likely include different pathophysiologic mechanisms by identifying specific pathways associated with each OCT feature. Financial Disclosures Proprietary or commercial disclosure may be found after the references.
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Affiliation(s)
- Ines Lains
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts
| | - Xikun Han
- Department of Epidemiology, Harvard T H Chan School of Public Health, Boston, Massachusetts
- Program in Genetic Epidemiology and Statistical Genetics, Harvard T H Chan School of Public Health, Boston, Massachusetts
| | - João Gil
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal
- Ophthalmology Department, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal
- Association for Innovation and Biomedical Research on Light and Image, Coimbra, Portugal
| | - Joana Providencia
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal
- Ophthalmology Department, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal
- Association for Innovation and Biomedical Research on Light and Image, Coimbra, Portugal
| | - Archana Nigalye
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts
| | - Rodrigo Alvarez
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts
| | - Vivian Paraskevi Douglas
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts
| | - Kevin Mendez
- Systems Genetics and Genomics Unit, Channing Division of Network Medicine Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Raviv Katz
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts
| | - Gregory Tsougranis
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts
| | - Jinglun Li
- Department of Biostatistics, Harvard T H Chan School of Public Health, Boston, Massachusetts
| | - Rachel S. Kelly
- Systems Genetics and Genomics Unit, Channing Division of Network Medicine Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Ivana K. Kim
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts
| | - Jessica Lasky-Su
- Systems Genetics and Genomics Unit, Channing Division of Network Medicine Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Rufino Silva
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal
- Ophthalmology Department, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal
- Association for Innovation and Biomedical Research on Light and Image, Coimbra, Portugal
- Clinical Academic Center of Coimbra (CCAC), Coimbra, Portugal
| | - Joan W. Miller
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts
| | - Liming Liang
- Department of Biostatistics, Harvard T H Chan School of Public Health, Boston, Massachusetts
| | - Demetrios Vavvas
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts
| | - John B. Miller
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts
| | - Deeba Husain
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts
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5
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Różanowska MB. Lipofuscin, Its Origin, Properties, and Contribution to Retinal Fluorescence as a Potential Biomarker of Oxidative Damage to the Retina. Antioxidants (Basel) 2023; 12:2111. [PMID: 38136230 PMCID: PMC10740933 DOI: 10.3390/antiox12122111] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 12/05/2023] [Accepted: 12/09/2023] [Indexed: 12/24/2023] Open
Abstract
Lipofuscin accumulates with age as intracellular fluorescent granules originating from incomplete lysosomal digestion of phagocytosed and autophagocytosed material. The purpose of this review is to provide an update on the current understanding of the role of oxidative stress and/or lysosomal dysfunction in lipofuscin accumulation and its consequences, particularly for retinal pigment epithelium (RPE). Next, the fluorescence of lipofuscin, spectral changes induced by oxidation, and its contribution to retinal fluorescence are discussed. This is followed by reviewing recent developments in fluorescence imaging of the retina and the current evidence on the prognostic value of retinal fluorescence for the progression of age-related macular degeneration (AMD), the major blinding disease affecting elderly people in developed countries. The evidence of lipofuscin oxidation in vivo and the evidence of increased oxidative damage in AMD retina ex vivo lead to the conclusion that imaging of spectral characteristics of lipofuscin fluorescence may serve as a useful biomarker of oxidative damage, which can be helpful in assessing the efficacy of potential antioxidant therapies in retinal degenerations associated with accumulation of lipofuscin and increased oxidative stress. Finally, amendments to currently used fluorescence imaging instruments are suggested to be more sensitive and specific for imaging spectral characteristics of lipofuscin fluorescence.
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Affiliation(s)
- Małgorzata B. Różanowska
- School of Optometry and Vision Sciences, College of Biomedical and Life Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, Wales, UK;
- Cardiff Institute for Tissue Engineering and Repair (CITER), Redwood Building, King Edward VII Avenue, Cardiff CF10 3NB, Wales, UK
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Lieffrig SA, Gyimesi G, Mao Y, Finnemann SC. Clearance phagocytosis by the retinal pigment epithelial during photoreceptor outer segment renewal: Molecular mechanisms and relation to retinal inflammation. Immunol Rev 2023; 319:81-99. [PMID: 37555340 PMCID: PMC10615845 DOI: 10.1111/imr.13264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 07/18/2023] [Indexed: 08/10/2023]
Abstract
Mammalian photoreceptor outer segment renewal is a highly coordinated process that hinges on timed cell signaling between photoreceptor neurons and the adjacent retinal pigment epithelial (RPE). It is a strictly rhythmic, synchronized process that underlies in part circadian regulation. We highlight findings from recently developed methods that quantify distinct phases of outer segment renewal in retinal tissue. At light onset, outer segments expose the conserved "eat-me" signal phosphatidylserine exclusively at their distal, most aged tip. A coordinated two-receptor efferocytosis process follows, in which ligands bridge outer segment phosphatidylserine with the RPE receptors αvβ5 integrin, inducing cytosolic signaling toward Rac1 and focal adhesion kinase/MERTK, and with MERTK directly, additionally inhibiting RhoA/ROCK and thus enabling F-actin dynamics favoring outer segment fragment engulfment. Photoreceptors and RPE persist for life with each RPE cell in the eye servicing dozens of overlying photoreceptors. Thus, RPE cells phagocytose more often and process more material than any other cell type. Mutant mice with impaired outer segment renewal largely retain functional photoreceptors and retinal integrity. However, when anti-inflammatory signaling in the RPE via MERTK or the related TYRO3 is lacking, catastrophic inflammation leads to immune cell infiltration that swiftly destroys the retina causing blindness.
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Affiliation(s)
- Stephanie A. Lieffrig
- Center for Cancer, Genetic Diseases and Gene Regulation, Department of Biological Sciences, Fordham University, Bronx, NY
| | - Gavin Gyimesi
- Center for Cancer, Genetic Diseases and Gene Regulation, Department of Biological Sciences, Fordham University, Bronx, NY
| | | | - Silvia C. Finnemann
- Center for Cancer, Genetic Diseases and Gene Regulation, Department of Biological Sciences, Fordham University, Bronx, NY
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7
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Dontsov AE, Yakovleva MA, Vasin AA, Gulin AA, Aybush AV, Nadtochenko VA, Ostrovsky MA. Understanding the Mechanism of Light-Induced Age-Related Decrease in Melanin Concentration in Retinal Pigment Epithelium Cells. Int J Mol Sci 2023; 24:13099. [PMID: 37685907 PMCID: PMC10487480 DOI: 10.3390/ijms241713099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 08/13/2023] [Accepted: 08/18/2023] [Indexed: 09/10/2023] Open
Abstract
It is known that during the process of aging, there is a significant decrease in the number of melanosomes in the retinal pigment epithelium (RPE) cells in the human eye. Melanosomes act as screening pigments in RPE cells and are fundamentally important for protection against the free radicals generated by light. A loss or change in the quality of melanin in melanosomes can lead to the development of senile pathologies and aggravation in the development of various retinal diseases. We have previously shown that the interaction between melanin melanosomes and superoxide radicals results in oxidative degradation with the formation of water-soluble fluorescent products. In the present study, we show, using fluorescence analysis, HPLC, and mass spectrometry, that visible light irradiation on melanolipofuscin granules isolated from RPE cells in the human eye results in the formation of water-soluble fluorescent products from oxidative degradation of melanin, which was in contrast to lipofuscin granules and melanosomes irradiation. The formation of these products occurs as a result of the oxidative degradation of melanin by superoxide radicals, which are generated by the lipofuscin part of the melanolipofuscin granule. We identified these products both in the composition of melanolipofuscin granules irradiated with visible light and in the composition of melanosomes that were not irradiated but were, instead, oxidized by superoxide radicals. In the melanolipofuscin granules irradiated by visible light, ions that could be associated with melanin oxidative degradation products were identified by applying the principal component analysis of the time-of-flight secondary ion mass spectrometry (ToF-SIMS) data. Degradation of the intact melanosomes by visible light is also possible; however, this requires significantly higher irradiation intensities than for melanolipofuscin granules. It is concluded that the decrease in the concentration of melanin in RPE cells in the human eye with age is due to its oxidative degradation by reactive oxygen species generated by lipofuscin, as part of the melanolipofuscin granules, under the action of light.
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Affiliation(s)
- Alexander E. Dontsov
- Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, 119334 Moscow, Russia; (M.A.Y.); (M.A.O.)
| | - Marina A. Yakovleva
- Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, 119334 Moscow, Russia; (M.A.Y.); (M.A.O.)
| | - Alexander A. Vasin
- Federal Research Center of Chemical Physics, Russian Academy of Sciences, N.N. Semenov RAS, 119991 Moscow, Russia; (A.A.V.); (A.A.G.); (A.V.A.); (V.A.N.)
| | - Alexander A. Gulin
- Federal Research Center of Chemical Physics, Russian Academy of Sciences, N.N. Semenov RAS, 119991 Moscow, Russia; (A.A.V.); (A.A.G.); (A.V.A.); (V.A.N.)
| | - Arseny V. Aybush
- Federal Research Center of Chemical Physics, Russian Academy of Sciences, N.N. Semenov RAS, 119991 Moscow, Russia; (A.A.V.); (A.A.G.); (A.V.A.); (V.A.N.)
| | - Viktor A. Nadtochenko
- Federal Research Center of Chemical Physics, Russian Academy of Sciences, N.N. Semenov RAS, 119991 Moscow, Russia; (A.A.V.); (A.A.G.); (A.V.A.); (V.A.N.)
| | - Mikhail A. Ostrovsky
- Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, 119334 Moscow, Russia; (M.A.Y.); (M.A.O.)
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Lyu Y, Tschulakow AV, Wang K, Brash DE, Schraermeyer U. Chemiexcitation and melanin in photoreceptor disc turnover and prevention of macular degeneration. Proc Natl Acad Sci U S A 2023; 120:e2216935120. [PMID: 37155898 PMCID: PMC10194005 DOI: 10.1073/pnas.2216935120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 04/03/2023] [Indexed: 05/10/2023] Open
Abstract
Age-related macular degeneration, Stargardt disease, and their Abca4-/- mouse model are characterized by accelerated accumulation of the pigment lipofuscin, derived from photoreceptor disc turnover in the retinal pigment epithelium (RPE); lipofuscin accumulation and retinal degeneration both occur earlier in albino mice. Intravitreal injection of superoxide (O2•-) generators reverses lipofuscin accumulation and rescues retinal pathology, but neither the target nor mechanism is known. Here we show that RPE contains thin multi-lamellar membranes (TLMs) resembling photoreceptor discs, which associate with melanolipofuscin granules in pigmented mice but in albinos are 10-fold more abundant and reside in vacuoles. Genetically over-expressing tyrosinase in albinos generates melanosomes and decreases TLM-related lipofuscin. Intravitreal injection of generators of O2•- or nitric oxide (•NO) decreases TLM-related lipofuscin in melanolipofuscin granules of pigmented mice by ~50% in 2 d, but not in albinos. Prompted by evidence that O2•- plus •NO creates a dioxetane on melanin that excites its electrons to a high-energy state (termed "chemiexcitation"), we show that exciting electrons directly using a synthetic dioxetane reverses TLM-related lipofuscin even in albinos; quenching the excited-electron energy blocks this reversal. Melanin chemiexcitation assists in safe photoreceptor disc turnover.
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Affiliation(s)
- Yanan Lyu
- Division of Experimental Vitreoretinal Surgery, Centre for Ophthalmology, University of Tuebingen, Tuebingen72076, Germany
| | - Alexander V. Tschulakow
- Division of Experimental Vitreoretinal Surgery, Centre for Ophthalmology, University of Tuebingen, Tuebingen72076, Germany
- OcuTox GmbH, Preclinical Drug Assessment, Hechingen72379, Germany
| | - Kun Wang
- Division of Experimental Vitreoretinal Surgery, Centre for Ophthalmology, University of Tuebingen, Tuebingen72076, Germany
| | - Douglas E. Brash
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT06520-8040
- Yale Comprehensive Cancer Center, Yale University School of Medicine, New Haven, CT06520-8028
| | - Ulrich Schraermeyer
- Division of Experimental Vitreoretinal Surgery, Centre for Ophthalmology, University of Tuebingen, Tuebingen72076, Germany
- OcuTox GmbH, Preclinical Drug Assessment, Hechingen72379, Germany
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9
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Dhingra A, Tobias JW, Philp NJ, Boesze-Battaglia K. Transcriptomic Changes Predict Metabolic Alterations in LC3 Associated Phagocytosis in Aged Mice. Int J Mol Sci 2023; 24:6716. [PMID: 37047689 PMCID: PMC10095460 DOI: 10.3390/ijms24076716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 03/28/2023] [Accepted: 03/28/2023] [Indexed: 04/14/2023] Open
Abstract
LC3b (Map1lc3b) plays an essential role in canonical autophagy and is one of several components of the autophagy machinery that mediates non-canonical autophagic functions. Phagosomes are often associated with lipidated LC3b to promote phagosome maturation in a process called LC3-associated phagocytosis (LAP). Specialized phagocytes, such as mammary epithelial cells, retinal pigment epithelial (RPE) cells, and sertoli cells, utilize LAP for optimal degradation of phagocytosed material, including debris. In the visual system, LAP is critical to maintain retinal function, lipid homeostasis, and neuroprotection. In a mouse model of retinal lipid steatosis-mice lacking LC3b (LC3b-/-), we observed increased lipid deposition, metabolic dysregulation, and enhanced inflammation. Herein, we present a non-biased approach to determine if loss of LAP mediated processes modulate the expression of various genes related to metabolic homeostasis, lipid handling, and inflammation. A comparison of the RPE transcriptome of WT and LC3b-/- mice revealed 1533 DEGs, with ~73% upregulated and 27% downregulated. Enriched gene ontology (GO) terms included inflammatory response (upregulated DEGs), fatty acid metabolism, and vascular transport (downregulated DEGs). Gene set enrichment analysis (GSEA) identified 34 pathways; 28 were upregulated (dominated by inflammation/related pathways) and 6 were downregulated (dominated by metabolic pathways). Analysis of additional gene families identified significant differences for genes in the solute carrier family, RPE signature genes, and genes with a potential role in age-related macular degeneration. These data indicate that loss of LC3b induces robust changes in the RPE transcriptome contributing to lipid dysregulation and metabolic imbalance, RPE atrophy, inflammation, and disease pathophysiology.
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Affiliation(s)
- Anuradha Dhingra
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - John W. Tobias
- Penn Genomics and Sequencing Core, Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Nancy J. Philp
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Kathleen Boesze-Battaglia
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
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10
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Dhingra A, Tobias JW, Philp NJ, Boesze-Battaglia K. Transcriptomic changes predict metabolic alterations in LC3 associated phagocytosis in aged mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.14.532586. [PMID: 36993501 PMCID: PMC10054970 DOI: 10.1101/2023.03.14.532586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Abstract
LC3b ( Map1lc3b ) plays an essential role in canonical autophagy and is one of several components of the autophagy machinery that mediates non-canonical autophagic functions. Phagosomes are often associated with lipidated LC3b, to pro-mote phagosome maturation in a process called LC3-associated phagocytosis (LAP). Specialized phagocytes such as mammary epithelial cells, retinal pigment epithelial (RPE) cells, and sertoli cells utilize LAP for optimal degradation of phagocytosed material, including debris. In the visual system, LAP is critical to maintain retinal function, lipid homeostasis and neuroprotection. In a mouse model of retinal lipid steatosis - mice lacking LC3b ( LC3b -/- ), we observed increased lipid deposition, metabolic dysregulation and enhanced inflammation. Herein we present a non-biased approach to determine if loss of LAP mediated processes modulate the expression of various genes related to metabolic homeostasis, lipid handling, and inflammation. A comparison of the RPE transcriptome of WT and LC3b -/- mice revealed 1533 DEGs, with ~73% upregulated and 27% down-regulated. Enriched gene ontology (GO) terms included inflammatory response (upregulated DEGs), fatty acid metabolism and vascular transport (downregulated DEGs). Gene set enrichment analysis (GSEA) identified 34 pathways; 28 were upregulated (dominated by inflammation/related pathways) and 6 were downregulated (dominated by metabolic pathways). Analysis of additional gene families identified significant differences for genes in the solute carrier family, RPE signature genes, and genes with potential role in age-related macular degeneration. These data indicate that loss of LC3b induces robust changes in the RPE transcriptome contributing to lipid dysregulation and metabolic imbalance, RPE atrophy, inflammation, and disease pathophysiology.
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11
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Monsour CG, Tadle AB, Tafolla-Aguirre BJ, Lakshmanan N, Yoon JH, Sabio RB, Selke M. Singlet Oxygen Quenching by Resveratrol Derivatives. Photochem Photobiol 2023; 99:672-679. [PMID: 36031343 PMCID: PMC9971345 DOI: 10.1111/php.13704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 08/24/2022] [Indexed: 11/29/2022]
Abstract
We investigated the singlet oxygen quenching ability of several derivatives of trans-resveratrol which have been reported to have significant antioxidant ability, including photoprotective activity. We measured the total rate constants of singlet oxygen removal (kT ) by the methylated resveratrol derivative 1,3-dimethoxy-5-[(E)-2-(4-methoxyphenyl)ethenyl]benzene, and the partially methylated resveratrol derivatives 4-((E)-2-(3,5-dimethoxyphenyl)ethenyl)phenol (pterostilbene), 5-[(E)-2-(4-methoxyphenyl)ethenyl]benzene-1,3-diol and (2R,3R)-3,5,7-trihydroxy-2-(3,4,5-trihydroxyphenyl)-2,3-dihydrochromen-4-one (dihydromyricetin). A protic solvent system results in higher kT values, except for the completely methylated derivative. We also investigated the ability of trans-resveratrol to directly act as a photosensitizer (rather than via secondary photoproducts resulting from other primary photochemical reactions) for the production of singlet oxygen but found that neither resveratrol nor any of its derivatives are able to do so. We then studied the chemical reactions of the methylated derivative with singlet oxygen. The main pathway consists of a [4 + 2] cycloaddition reaction involving the trans-double bond and the para-substituted benzene ring similar to what has been observed for trans-resveratrol. Unlike trans-resveratrol, the primary singlet oxygen product undergoes a second [4 + 2] cycloaddition with singlet oxygen leading to the formation of diendoperoxides. A second reactivity pathway for both trans-resveratrol and the methylated derivative leads to the formation of aldehydes via cleavage of a transient dioxetane.
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Affiliation(s)
- Charlotte G. Monsour
- Department of Chemistry and Biochemistry, California State University, Los Angeles
| | - Abegail B. Tadle
- Department of Chemistry and Biochemistry, California State University, Los Angeles
| | | | - Nidhi Lakshmanan
- Department of Chemistry and Biochemistry, California State University, Los Angeles
| | - Jin Hyeok Yoon
- Department of Chemistry and Biochemistry, California State University, Los Angeles
| | - Rhemrose B. Sabio
- Department of Chemistry and Biochemistry, California State University, Los Angeles
| | - Matthias Selke
- Department of Chemistry and Biochemistry, California State University, Los Angeles
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Arunkumar R, Bernstein PS. Macular Pigment Carotenoids and Bisretinoid A2E. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1415:15-20. [PMID: 37440008 DOI: 10.1007/978-3-031-27681-1_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Lutein (L), zeaxanthin (Z), and meso-zeaxanthin (MZ) are the three macular pigments (MP) carotenoids that uniquely accumulate in the macula lutea region of the human retina. L and Z are obtained by humans through dietary intake. The third MP, MZ, is rarely present in diet, and its abundance in the human fovea is due to the metabolic conversion of dietary L by the retinal pigment epithelium's RPE65 enzyme. The major functions of MP in ocular health are to filter high-intensity, phototoxic blue light and to act as effective antioxidants for scavenging free radicals. The pyridinium bisretinoid, N-retinylidene-N-retinylethanolamine (A2E), contributes to drusen formation in dry age-related macular degeneration (AMD) and to the autofluorescent flecks in autosomal recessive Stargardt disease (STGD1). Retinal carotenoids attenuate A2E formation and can directly and indirectly alleviate A2E-mediated oxidative damage. In this chapter, we review these more recently recognized interconnections between MP carotenoids and A2E bisretinoids.
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Affiliation(s)
- Ranganathan Arunkumar
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Paul S Bernstein
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA.
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Oxidative Stress, Neuroinflammation and Neurodegeneration: The Chicken, the Egg and the Dinosaur. Antioxidants (Basel) 2022; 11:antiox11081554. [PMID: 36009273 PMCID: PMC9405268 DOI: 10.3390/antiox11081554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 08/09/2022] [Indexed: 11/24/2022] Open
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Feldman TB, Dontsov AE, Yakovleva MA, Ostrovsky MA. Photobiology of lipofuscin granules in the retinal pigment epithelium cells of the eye: norm, pathology, age. Biophys Rev 2022; 14:1051-1065. [PMID: 36124271 PMCID: PMC9481861 DOI: 10.1007/s12551-022-00989-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 07/26/2022] [Indexed: 01/10/2023] Open
Abstract
Lipofuscin granules (LGs) are accumulated in the retinal pigment epithelium (RPE) cells. The progressive LG accumulation can somehow lead to pathology and accelerate the aging process. The review examines composition, spectral properties and photoactivity of LGs isolated from the human cadaver eyes. By use of atomic force microscopy and near-field microscopy, we have revealed the fluorescent heterogeneity of LGs. We have discovered the generation of reactive oxygen species by LGs, and found that LGs and melanolipofuscin granules are capable of photoinduced oxidation of lipids. It was shown that A2E, as the main fluorophore (bisretinoid) of LGs, is much less active as an oxidation photosensitizer than other fluorophores (bisretinoids) of LGs. Photooxidized products of bisretinoids pose a much greater danger to the cell than non-oxidized one. Our studies of the fluorescent properties of LGs and their fluorophores (bisretinoids) showed for the first time that their spectral characteristics change (shift to the short-wavelength region) in pathology and after exposure to ionizing radiation. By recording the fluorescence spectra and fluorescence decay kinetics of oxidized products of LG fluorophores, it is possible to improve the methods of early diagnosis of degenerative diseases. Lipofuscin ("aging pigment") is not an inert "slag". The photoactivity of LGs can pose a significant danger to the RPE cells. Fluorescence characteristics of LGs are a tool to detect early stages of degeneration in the retina and RPE.
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Affiliation(s)
- T. B. Feldman
- Department of Biology, Lomonosov Moscow State University, Moscow, Russia
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - A. E. Dontsov
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - M. A. Yakovleva
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - M. A. Ostrovsky
- Department of Biology, Lomonosov Moscow State University, Moscow, Russia
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, Russia
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Peng W, Wu Y, Peng Z, Qi W, Liu T, Yang B, He D, Liu Y, Wang Y. Cyanidin-3-glucoside improves the barrier function of retinal pigment epithelium cells by attenuating endoplasmic reticulum stress-induced apoptosis. Food Res Int 2022; 157:111313. [DOI: 10.1016/j.foodres.2022.111313] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 04/24/2022] [Accepted: 04/26/2022] [Indexed: 12/27/2022]
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Dontsov A, Yakovleva M, Trofimova N, Sakina N, Gulin A, Aybush A, Gostev F, Vasin A, Feldman T, Ostrovsky M. Water-Soluble Products of Photooxidative Destruction of the Bisretinoid A2E Cause Proteins Modification in the Dark. Int J Mol Sci 2022; 23:ijms23031534. [PMID: 35163454 PMCID: PMC8836230 DOI: 10.3390/ijms23031534] [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: 01/21/2022] [Accepted: 01/26/2022] [Indexed: 01/06/2023] Open
Abstract
Aging of the retina is accompanied by a sharp increase in the content of lipofuscin granules and bisretinoid A2E in the cells of the retinal pigment epithelium (RPE) of the human eye. It is known that A2E can have a toxic effect on RPE cells. However, the specific mechanisms of the toxic effect of A2E are poorly understood. We investigated the effect of the products of photooxidative destruction of A2E on the modification of bovine serum albumin (BSA) and hemoglobin from bovine erythrocytes. A2E was irradiated with a blue light-emitting diode (LED) source (450 nm) or full visible light (400–700 nm) of a halogen lamp, and the resulting water-soluble products of photooxidative destruction were investigated for the content of carbonyl compounds by mass spectrometry and reaction with thiobarbituric acid. It has been shown that water-soluble products formed during A2E photooxidation and containing carbonyl compounds cause modification of serum albumin and hemoglobin, measured by an increase in fluorescence intensity at 440–455 nm. The antiglycation agent aminoguanidine inhibited the process of modification of proteins. It is assumed that water-soluble carbonyl products formed as a result of A2E photodestruction led to the formation of modified proteins, activation of the inflammation process, and, as a consequence, to the progression of various senile eye pathologies.
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Affiliation(s)
- Alexander Dontsov
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 119334 Moscow, Russia; (M.Y.); (N.T.); (N.S.); (T.F.); (M.O.)
- Correspondence: ; +7-495-939-7422
| | - Marina Yakovleva
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 119334 Moscow, Russia; (M.Y.); (N.T.); (N.S.); (T.F.); (M.O.)
| | - Natalia Trofimova
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 119334 Moscow, Russia; (M.Y.); (N.T.); (N.S.); (T.F.); (M.O.)
| | - Natalia Sakina
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 119334 Moscow, Russia; (M.Y.); (N.T.); (N.S.); (T.F.); (M.O.)
| | - Alexander Gulin
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 119991 Moscow, Russia; (A.G.); (A.A.); (F.G.); (A.V.)
| | - Arseny Aybush
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 119991 Moscow, Russia; (A.G.); (A.A.); (F.G.); (A.V.)
| | - Fedor Gostev
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 119991 Moscow, Russia; (A.G.); (A.A.); (F.G.); (A.V.)
| | - Alexander Vasin
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 119991 Moscow, Russia; (A.G.); (A.A.); (F.G.); (A.V.)
| | - Tatiana Feldman
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 119334 Moscow, Russia; (M.Y.); (N.T.); (N.S.); (T.F.); (M.O.)
- Department of Biology, Lomonosov Moscow State University, Leninskiye Gory 1, 119234 Moscow, Russia
| | - Mikhail Ostrovsky
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 119334 Moscow, Russia; (M.Y.); (N.T.); (N.S.); (T.F.); (M.O.)
- Department of Biology, Lomonosov Moscow State University, Leninskiye Gory 1, 119234 Moscow, Russia
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The Role of Vitamin A in Retinal Diseases. Int J Mol Sci 2022; 23:ijms23031014. [PMID: 35162940 PMCID: PMC8835581 DOI: 10.3390/ijms23031014] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 01/12/2022] [Accepted: 01/13/2022] [Indexed: 12/24/2022] Open
Abstract
Vitamin A is an essential fat-soluble vitamin that occurs in various chemical forms. It is essential for several physiological processes. Either hyper- or hypovitaminosis can be harmful. One of the most important vitamin A functions is its involvement in visual phototransduction, where it serves as the crucial part of photopigment, the first molecule in the process of transforming photons of light into electrical signals. In this process, large quantities of vitamin A in the form of 11-cis-retinal are being isomerized to all-trans-retinal and then quickly recycled back to 11-cis-retinal. Complex machinery of transporters and enzymes is involved in this process (i.e., the visual cycle). Any fault in the machinery may not only reduce the efficiency of visual detection but also cause the accumulation of toxic chemicals in the retina. This review provides a comprehensive overview of diseases that are directly or indirectly connected with vitamin A pathways in the retina. It includes the pathophysiological background and clinical presentation of each disease and summarizes the already existing therapeutic and prospective interventions.
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Różanowska MB, Różanowski B. Photodegradation of Lipofuscin in Suspension and in ARPE-19 Cells and the Similarity of Fluorescence of the Photodegradation Product with Oxidized Docosahexaenoate. Int J Mol Sci 2022; 23:ijms23020922. [PMID: 35055111 PMCID: PMC8778276 DOI: 10.3390/ijms23020922] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 01/07/2022] [Accepted: 01/12/2022] [Indexed: 02/01/2023] Open
Abstract
Retinal lipofuscin accumulates with age in the retinal pigment epithelium (RPE), where its fluorescence properties are used to assess retinal health. It was observed that there is a decrease in lipofuscin fluorescence above the age of 75 years and in the early stages of age-related macular degeneration (AMD). The purpose of this study was to investigate the response of lipofuscin isolated from human RPE and lipofuscin-laden cells to visible light, and to determine whether an abundant component of lipofuscin, docosahexaenoate (DHA), can contribute to lipofuscin fluorescence upon oxidation. Exposure of lipofuscin to visible light leads to a decrease in its long-wavelength fluorescence at about 610 nm, with a concomitant increase in the short-wavelength fluorescence. The emission spectrum of photodegraded lipofuscin exhibits similarity with that of oxidized DHA. Exposure of lipofuscin-laden cells to light leads to a loss of lipofuscin granules from cells, while retaining cell viability. The spectral changes in fluorescence in lipofuscin-laden cells resemble those seen during photodegradation of isolated lipofuscin. Our results demonstrate that fluorescence emission spectra, together with quantitation of the intensity of long-wavelength fluorescence, can serve as a marker useful for lipofuscin quantification and for monitoring its oxidation, and hence useful for screening the retina for increased oxidative damage and early AMD-related changes.
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Affiliation(s)
- Małgorzata B. Różanowska
- School of Optometry and Vision Sciences, Cardiff University, Cardiff CF24 4HQ, UK
- Cardiff Institute for Tissue Engineering and Repair (CITER), Cardiff University, Cardiff CF10 3NB, UK
- Correspondence: ; Tel.: +44-2920875057
| | - Bartosz Różanowski
- Institute of Biology, Pedagogical University of Kraków, 30-084 Kraków, Poland;
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