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Rozanowska M, Edge R, Land EJ, Navaratnam S, Sarna T, Truscott TG. Scavenging of Cation Radicals of the Visual Cycle Retinoids by Lutein, Zeaxanthin, Taurine, and Melanin. Int J Mol Sci 2023; 25:506. [PMID: 38203675 PMCID: PMC10779001 DOI: 10.3390/ijms25010506] [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: 11/18/2023] [Revised: 12/26/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
In the retina, retinoids involved in vision are under constant threat of oxidation, and their oxidation products exhibit deleterious properties. Using pulse radiolysis, this study determined that the bimolecular rate constants of scavenging cation radicals of retinoids by taurine are smaller than 2 × 107 M-1s-1 whereas lutein scavenges cation radicals of all three retinoids with the bimolecular rate constants approach the diffusion-controlled limits, while zeaxanthin is only 1.4-1.6-fold less effective. Despite that lutein exhibits greater scavenging rate constants of retinoid cation radicals than other antioxidants, the greater concentrations of ascorbate in the retina suggest that ascorbate may be the main protectant of all visual cycle retinoids from oxidative degradation, while α-tocopherol may play a substantial role in the protection of retinaldehyde but is relatively inefficient in the protection of retinol or retinyl palmitate. While the protection of retinoids by lutein and zeaxanthin appears inefficient in the retinal periphery, it can be quite substantial in the macula. Although the determined rate constants of scavenging the cation radicals of retinol and retinaldehyde by dopa-melanin are relatively small, the high concentration of melanin in the RPE melanosomes suggests they can be scavenged if they are in proximity to melanin-containing pigment granules.
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Affiliation(s)
- Malgorzata Rozanowska
- Cardiff Institute of Tissue Engineering and Repair, Cardiff University, Cardiff CF10 3AX, UK
- School of Optometry and Vision Sciences, Cardiff University, Cardiff CF24 4HQ, UK
| | - Ruth Edge
- Dalton Cumbrian Facility, The University of Manchester, Westlakes Science Park, Moor Row, Cumbria CA24 3HA, UK;
| | - Edward J. Land
- The Paterson Institute, The University of Manchester, Wilmslow Road, Manchester M20 4BX, UK;
| | - Suppiah Navaratnam
- Biomedical Sciences Research Institute, University of Salford, Manchester M5 4WT, UK;
| | - Tadeusz Sarna
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland;
| | - T. George Truscott
- School of Chemical and Physical Sciences, Lennard-Jones Building, Keele University, Staffordshire ST5 5BG, UK;
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2
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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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3
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Kiser PD. Retinal pigment epithelium 65 kDa protein (RPE65): An update. Prog Retin Eye Res 2021; 88:101013. [PMID: 34607013 PMCID: PMC8975950 DOI: 10.1016/j.preteyeres.2021.101013] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 09/21/2021] [Accepted: 09/24/2021] [Indexed: 12/21/2022]
Abstract
Vertebrate vision critically depends on an 11-cis-retinoid renewal system known as the visual cycle. At the heart of this metabolic pathway is an enzyme known as retinal pigment epithelium 65 kDa protein (RPE65), which catalyzes an unusual, possibly biochemically unique, reaction consisting of a coupled all-trans-retinyl ester hydrolysis and alkene geometric isomerization to produce 11-cis-retinol. Early work on this isomerohydrolase demonstrated its membership to the carotenoid cleavage dioxygenase superfamily and its essentiality for 11-cis-retinal production in the vertebrate retina. Three independent studies published in 2005 established RPE65 as the actual isomerohydrolase instead of a retinoid-binding protein as previously believed. Since the last devoted review of RPE65 enzymology appeared in this journal, major advances have been made in a number of areas including our understanding of the mechanistic details of RPE65 isomerohydrolase activity, its phylogenetic origins, the relationship of its membrane binding affinity to its catalytic activity, its role in visual chromophore production for rods and cones, its modulation by macromolecules and small molecules, and the involvement of RPE65 mutations in the development of retinal diseases. In this article, I will review these areas of progress with the goal of integrating results from the varied experimental approaches to provide a comprehensive picture of RPE65 biochemistry. Key outstanding questions that may prove to be fruitful future research pursuits will also be highlighted.
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Affiliation(s)
- Philip D Kiser
- Research Service, VA Long Beach Healthcare System, Long Beach, CA, 90822, USA; Department of Physiology & Biophysics, University of California, Irvine School of Medicine, Irvine, CA, 92697, USA; Department of Ophthalmology and Center for Translational Vision Research, Gavin Herbert Eye Institute, University of California, Irvine School of Medicine, Irvine, CA, 92697, USA.
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4
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Tonade D, Kern TS. Photoreceptor cells and RPE contribute to the development of diabetic retinopathy. Prog Retin Eye Res 2021; 83:100919. [PMID: 33188897 PMCID: PMC8113320 DOI: 10.1016/j.preteyeres.2020.100919] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 10/27/2020] [Accepted: 10/31/2020] [Indexed: 12/26/2022]
Abstract
Diabetic retinopathy (DR) is a leading cause of blindness. It has long been regarded as vascular disease, but work in the past years has shown abnormalities also in the neural retina. Unfortunately, research on the vascular and neural abnormalities have remained largely separate, instead of being integrated into a comprehensive view of DR that includes both the neural and vascular components. Recent evidence suggests that the most predominant neural cell in the retina (photoreceptors) and the adjacent retinal pigment epithelium (RPE) play an important role in the development of vascular lesions characteristic of DR. This review summarizes evidence that the outer retina is altered in diabetes, and that photoreceptors and RPE contribute to retinal vascular alterations in the early stages of the retinopathy. The possible molecular mechanisms by which cells of the outer retina might contribute to retinal vascular damage in diabetes also are discussed. Diabetes-induced alterations in the outer retina represent a novel therapeutic target to inhibit DR.
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Affiliation(s)
- Deoye Tonade
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
| | - Timothy S Kern
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA; Veterans Administration Medical Center Research Service, Cleveland, OH, USA; Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA, USA; Veterans Administration Medical Center Research Service, Long Beach, CA, USA.
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5
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Yu G, Gao SQ, Dong Z, Sheng L, Sun D, Zhang N, Zhang J, Margeivicus S, Fu P, Golczak M, Maeda A, Palczewski K, Lu ZR. Peptide Derivatives of Retinylamine Prevent Retinal Degeneration with Minimal Side Effects on Vision in Mice. Bioconjug Chem 2021; 32:572-583. [PMID: 33677964 DOI: 10.1021/acs.bioconjchem.1c00043] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Safe and effective molecular therapeutics for prophylactic treatment of retinal degenerative diseases are greatly needed. Disruptions in the clearance of all-trans-retinal (atRAL) by the visual (retinoid) cycle of the retina can lead to the accumulation of atRAL and its condensation products known to initiate progressive retinal dystrophy. Retinylamine (Ret-NH2) and its analogues are known to be effective in lowering the concentration of atRAL within the eye and thus preventing retinal degeneration in mouse models of human retinopathies. Here, we chemically modified Ret-NH2 with amino acids and peptides to improve the stability and ocular bioavailability of the resulting derivatives and to minimize their side effects. Fourteen Ret-NH2 derivatives were synthesized and tested in vitro and in vivo. These derivatives exhibited structure-dependent therapeutic efficacy in preventing light-induced retinal degeneration in Abca4-/-Rdh8-/- double-knockout mice, with the compounds containing glycine and/or L-valine generally exhibiting greater protective effects than Ret-NH2 or other tested amino acid derivatives of Ret-NH2. Ret-NH2-L-valylglycine amide (RVG) exhibited good stability in storage; and effective uptake and prolonged retention in mouse eyes. RVG readily formed a Schiff base with atRAL and did not inhibit RPE65 enzymatic activity. Administered by oral gavage, this retinoid also provided effective protection against light-induced retinal degeneration in Abca4-/-Rdh8-/- mice. Notably, the treatment with RVG had minimal effects on the regeneration of 11-cis-retinal and recovery of retinal function. RVG holds promise as a lead therapy for effective and safe treatment of human retinal degenerative diseases.
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Affiliation(s)
- Guanping Yu
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Song-Qi Gao
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Zhiqian Dong
- Center for Translation Vision Research, Gavin Herbert Eye Institute, Departments of Ophthalmology, Physiology & Biophysics, and Chemistry, University of California, Irvine, California 92697, United States
| | - Li Sheng
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Da Sun
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Ning Zhang
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Jianye Zhang
- Center for Translation Vision Research, Gavin Herbert Eye Institute, Departments of Ophthalmology, Physiology & Biophysics, and Chemistry, University of California, Irvine, California 92697, United States
| | - Seunghee Margeivicus
- Department of Epidemiology and Biostatistics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Pingfu Fu
- Department of Epidemiology and Biostatistics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Marcin Golczak
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Akiko Maeda
- Center for Translation Vision Research, Gavin Herbert Eye Institute, Departments of Ophthalmology, Physiology & Biophysics, and Chemistry, University of California, Irvine, California 92697, United States.,Department of Ophthalmology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Krzysztof Palczewski
- Center for Translation Vision Research, Gavin Herbert Eye Institute, Departments of Ophthalmology, Physiology & Biophysics, and Chemistry, University of California, Irvine, California 92697, United States
| | - Zheng-Rong Lu
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
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6
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Taveau N, Cubizolle A, Guillou L, Pinquier N, Moine E, Cia D, Kalatzis V, Vercauteren J, Durand T, Crauste C, Brabet P. Preclinical pharmacology of a lipophenol in a mouse model of light-induced retinopathy. Exp Mol Med 2020; 52:1090-1101. [PMID: 32641711 PMCID: PMC8080701 DOI: 10.1038/s12276-020-0460-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 04/18/2020] [Accepted: 04/21/2020] [Indexed: 12/17/2022] Open
Abstract
Environmental light has deleterious effects on the outer retina in human retinopathies, such as ABCA4-related Stargardt’s disease and dry age-related macular degeneration. These effects involve carbonyl and oxidative stress, which contribute to retinal cell death and vision loss. Here, we used an albino Abca4−/− mouse model, the outer retina of which shows susceptibility to acute photodamage, to test the protective efficacy of a new polyunsaturated fatty acid lipophenol derivative. Anatomical and functional analyses demonstrated that a single intravenous injection of isopropyl-phloroglucinol-DHA, termed IP-DHA, dose-dependently decreased light-induced photoreceptor degeneration and preserved visual sensitivity. This protective effect persisted for 3 months. IP-DHA did not affect the kinetics of the visual cycle in vivo or the activity of the RPE65 isomerase in vitro. Moreover, IP-DHA administered by oral gavage showed significant protection of photoreceptors against acute light damage. In conclusion, short-term tests in Abca4-deficient mice, following single-dose administration and light exposure, identify IP-DHA as a therapeutic agent for the prevention of retinal degeneration. Treating retinal damage in both aging and young patients might now be easier, thanks to treatment with a lipophenol, an omega-3 fatty acid linked to an antioxidant. The retina is the part of the eye that senses light, aided by light-sensitive pigments. However, these light-sensitive pigments can be converted by light to toxic byproducts, and in some individuals, these toxic byproducts can accumulate, damaging the retina and leading to vision loss. Philippe Brabet at the Montpellier Institute of Neuroscience in France and co-workers found that lipophenol treatment protected retinal cells from damage in a mouse model of retinal disease, and that a single dose has been effective in preserving vision. These results may help in finding new treatments for retinal diseases such as Stargardt disease and age-related macular degeneration.
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Affiliation(s)
- Nicolas Taveau
- Institut des Neurosciences de Montpellier, INSERM U1051, F-34091, Montpellier, France.,Université de Montpellier, F-34091, Montpellier, France
| | - Aurélie Cubizolle
- Institut des Neurosciences de Montpellier, INSERM U1051, F-34091, Montpellier, France.,Université de Montpellier, F-34091, Montpellier, France
| | - Laurent Guillou
- Institut des Neurosciences de Montpellier, INSERM U1051, F-34091, Montpellier, France.,Université de Montpellier, F-34091, Montpellier, France
| | - Nicolas Pinquier
- Institut des Neurosciences de Montpellier, INSERM U1051, F-34091, Montpellier, France
| | - Espérance Moine
- Institut des Biomolecules Max Mousseron (IBMM), UMR 5247 - Université de Montpellier, CNRS, ENSCM, F-34095, Montpellier, France
| | - David Cia
- Laboratoire de Biophysique Neurosensorielle, UMR INSERM 1107, Facultés de Médecine et de Pharmacie, F-63001, Clermont-Ferrand, France
| | - Vasiliki Kalatzis
- Institut des Neurosciences de Montpellier, INSERM U1051, F-34091, Montpellier, France.,Université de Montpellier, F-34091, Montpellier, France
| | - Joseph Vercauteren
- Institut des Biomolecules Max Mousseron (IBMM), UMR 5247 - Université de Montpellier, CNRS, ENSCM, F-34095, Montpellier, France
| | - Thierry Durand
- Institut des Biomolecules Max Mousseron (IBMM), UMR 5247 - Université de Montpellier, CNRS, ENSCM, F-34095, Montpellier, France
| | - Céline Crauste
- Institut des Biomolecules Max Mousseron (IBMM), UMR 5247 - Université de Montpellier, CNRS, ENSCM, F-34095, Montpellier, France
| | - Philippe Brabet
- Institut des Neurosciences de Montpellier, INSERM U1051, F-34091, Montpellier, France. .,Université de Montpellier, F-34091, Montpellier, France.
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7
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Racz B, Varadi A, Pearson PG, Petrukhin K. Comparative pharmacokinetics and pharmacodynamics of the advanced Retinol-Binding Protein 4 antagonist in dog and cynomolgus monkey. PLoS One 2020; 15:e0228291. [PMID: 31978148 PMCID: PMC6980506 DOI: 10.1371/journal.pone.0228291] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 01/10/2020] [Indexed: 12/23/2022] Open
Abstract
Accumulation of lipofuscin bisretinoids in the retina contributes to pathogenesis of macular degeneration. Retinol-Binding Protein 4 (RBP4) antagonists reduce serum retinol concentrations thus partially reducing retinol delivery to the retina which decreases bisretinoid synthesis. BPN-14136 is a novel RBP4 antagonist with good in vitro potency and selectivity and optimal rodent pharmacokinetic (PK) and pharmacodynamic (PD) characteristics. To select a non-rodent species for regulatory toxicology studies, we conducted PK and PD evaluation of BPN-14136 in dogs and non-human primates (NHP). PK properties were determined following oral and intravenous administration of BPN-14136 in beagle dogs and cynomolgus monkeys. Dynamics of plasma RBP4 reduction in response to compound administration was used as a PD marker. BPN-14136 exhibited favorable PK profile in both species. Dose-normalized exposure was significantly higher in NHP than in dog. Baseline concentrations of RBP4 were considerably lower in dog than in NHP, reflecting the atypical reliance of canids on non-RBP4 mechanisms of retinoid trafficking. Oral administration of BPN-14136 to NHP induced a strong 99% serum RBP4 reduction. Dynamics of RBP4 lowering in both species correlated with compound exposure. Despite adequate PK and PD characteristics of BPN-14136 in dog, reliance of canids on non-RBP4 mechanisms of retinoid trafficking precludes evaluation of on-target toxicities for RBP4 antagonists in this species. Strong RBP4 lowering combined with good PK attributes and high BPN-14136 exposure achieved in NHP, along with the biology of retinoid trafficking that is similar to that of humans, support the choice of NHP as a non-rodent safety species.
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Affiliation(s)
- Boglarka Racz
- Department of Ophthalmology, Columbia University, New York, New York, Unites States of America
| | - Andras Varadi
- Department of Ophthalmology, Columbia University, New York, New York, Unites States of America
| | - Paul G. Pearson
- Pearson Pharma Partners, Westlake Village, California, United States of America
| | - Konstantin Petrukhin
- Department of Ophthalmology, Columbia University, New York, New York, Unites States of America
- * E-mail:
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8
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Pharmacotherapy for metabolic and cellular stress in degenerative retinal diseases. Drug Discov Today 2019; 25:292-304. [PMID: 31809750 DOI: 10.1016/j.drudis.2019.11.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 11/08/2019] [Accepted: 11/26/2019] [Indexed: 12/13/2022]
Abstract
Retinal photoreceptors continually endure stresses associated with prolonged light exposure and the metabolic demands of dark adaptation. Although healthy photoreceptors are able to withstand these stresses for several decades, the disease-affected retina functions at a reduced capacity and is at an increased risk for dysfunction. To alleviate cellular and metabolic stressors in degenerative retinal diseases, a new class of drugs that modulate the metabolic activity of the retina have been developed. A clinical candidate in this class (emixustat) has been shown to reduce retinal pathology in various animal models of human retinal disease and is currently under clinical study. Here, we describe the pharmacological properties of emixustat, its mechanisms of action, and potential for use in the treatment of specific retinal diseases.
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9
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Silvaroli JA, Widjaja-Adhi MAK, Trischman T, Chelstowska S, Horwitz S, Banerjee S, Kiser PD, Blaner WS, Golczak M. Abnormal Cannabidiol Modulates Vitamin A Metabolism by Acting as a Competitive Inhibitor of CRBP1. ACS Chem Biol 2019; 14:434-448. [PMID: 30721022 DOI: 10.1021/acschembio.8b01070] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Cellular retinol-binding proteins (CRBPs) facilitate the uptake and intracellular transport of vitamin A. They integrate retinoid metabolism, playing an important role in regulating the synthesis of bioactive vitamin A metabolites. Thus, CRBPs constitute potential pharmacological targets to modulate cellular retinoid status that in turn may have applications in the treatment of certain immunological, metabolic, and ocular disorders. Here we identify abnormal cannabidiol (abn-CBD) as a nonretinoid inhibitor of cellular retinol-binding protein 1 (CRBP1). X-ray crystal structures of CRBP1 in complex with abn-CBD and its derivatives revealed a distinctive mode of protein-ligand interaction and provided a molecular basis for the high affinity and selectivity of this compound. We demonstrated that abn-CBD modulates the flux of retinoids via the retinoid cycle in vivo. Furthermore, the biological activity of abn-CBD was evidenced by its ability to protect against light-induced retinal damage in Balb/cJ mice. Altogether, our findings indicate that targeting selected CRBPs with a small-molecule inhibitor can potentially lead to the development of new therapeutic agents to counteract diseases with etiologies involving imbalance in retinoid metabolism or signaling.
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Affiliation(s)
| | | | | | | | | | - Surajit Banerjee
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, United States
- Northeastern Collaborative Access Team, Argonne National Laboratory, Argonne, IL, United States
| | - Philip D. Kiser
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, United States
| | - William S. Blaner
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY, United States
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10
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Daruich A, Le Rouzic Q, Jonet L, Naud MC, Kowalczuk L, Pournaras JA, Boatright JH, Thomas A, Turck N, Moulin A, Behar-Cohen F, Picard E. Iron is neurotoxic in retinal detachment and transferrin confers neuroprotection. SCIENCE ADVANCES 2019; 5:eaau9940. [PMID: 30662950 PMCID: PMC6326753 DOI: 10.1126/sciadv.aau9940] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 11/28/2018] [Indexed: 05/12/2023]
Abstract
In retinal detachment (RD), photoreceptor death and permanent vision loss are caused by neurosensory retina separating from the retinal pigment epithelium because of subretinal fluid (SRF), and successful surgical reattachment is not predictive of total visual recovery. As retinal iron overload exacerbates cell death in retinal diseases, we assessed iron as a predictive marker and therapeutic target for RD. In the vitreous and SRF from patients with RD, we measured increased iron and transferrin (TF) saturation that is correlated with poor visual recovery. In ex vivo and in vivo RD models, iron induces immediate necrosis and delayed apoptosis. We demonstrate that TF decreases both apoptosis and necroptosis induced by RD, and using RNA sequencing, pathways mediating the neuroprotective effects of TF are identified. Since toxic iron accumulates in RD, we propose TF supplementation as an adjunctive therapy to surgery for improving the visual outcomes of patients with RD.
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Affiliation(s)
- Alejandra Daruich
- INSERM, UMRS1138, Team 17, From physiopathology of ocular diseases to clinical development, Université Sorbonne Paris Cité, Centre de Recherche des Cordeliers, 15 rue de l’Ecole de Médecine, 75006 Paris, France
- Department of ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
- Ophthalmology Department, Necker-Enfants Malades University Hospital, AP-HP, Paris, France
| | - Quentin Le Rouzic
- INSERM, UMRS1138, Team 17, From physiopathology of ocular diseases to clinical development, Université Sorbonne Paris Cité, Centre de Recherche des Cordeliers, 15 rue de l’Ecole de Médecine, 75006 Paris, France
| | - Laurent Jonet
- INSERM, UMRS1138, Team 17, From physiopathology of ocular diseases to clinical development, Université Sorbonne Paris Cité, Centre de Recherche des Cordeliers, 15 rue de l’Ecole de Médecine, 75006 Paris, France
| | - Marie-Christine Naud
- INSERM, UMRS1138, Team 17, From physiopathology of ocular diseases to clinical development, Université Sorbonne Paris Cité, Centre de Recherche des Cordeliers, 15 rue de l’Ecole de Médecine, 75006 Paris, France
| | - Laura Kowalczuk
- Department of ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
| | - Jean-Antoine Pournaras
- Department of ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
| | - Jeffrey H. Boatright
- Department of Ophthalmology, School of Medicine, Emory University, Atlanta, GA, USA
- Center of Excellence, Atlanta Veterans Administration Medical Center, Decatur, GA, USA
| | - Aurélien Thomas
- Geneva University Hospitals, Unit of Toxicology, CURML, Geneva, Switzerland
- Faculty of Biology and Medicine, University of Lausanne, Rue du Bugnon 21, 1011 Lausanne, Switzerland
| | - Natacha Turck
- Faculty of Biology and Medicine, University of Lausanne, Rue du Bugnon 21, 1011 Lausanne, Switzerland
- Geneva University, Department of Human Protein Science, Geneva, Switzerland
| | - Alexandre Moulin
- Department of ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
| | - Francine Behar-Cohen
- INSERM, UMRS1138, Team 17, From physiopathology of ocular diseases to clinical development, Université Sorbonne Paris Cité, Centre de Recherche des Cordeliers, 15 rue de l’Ecole de Médecine, 75006 Paris, France
- Faculty of Biology and Medicine, University of Lausanne, Rue du Bugnon 21, 1011 Lausanne, Switzerland
- Ophtalmopole, Cochin Hospital, AP-HP, Assistance Publique Hôpitaux de Paris, 24 rue du Faubourg Saint-Jacques, 75014 Paris, France
- Corresponding author.
| | - Emilie Picard
- INSERM, UMRS1138, Team 17, From physiopathology of ocular diseases to clinical development, Université Sorbonne Paris Cité, Centre de Recherche des Cordeliers, 15 rue de l’Ecole de Médecine, 75006 Paris, France
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11
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Li S, Sato K, Gordon WC, Sendtner M, Bazan NG, Jin M. Ciliary neurotrophic factor (CNTF) protects retinal cone and rod photoreceptors by suppressing excessive formation of the visual pigments. J Biol Chem 2018; 293:15256-15268. [PMID: 30115683 DOI: 10.1074/jbc.ra118.004008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 08/15/2018] [Indexed: 12/25/2022] Open
Abstract
The retinal pigment epithelium (RPE)-dependent visual cycle provides 11-cis-retinal to opsins in the photoreceptor outer segments to generate functional visual pigments that initiate phototransduction in response to light stimuli. Both RPE65 isomerase of the visual cycle and the rhodopsin visual pigment have recently been identified as critical players in mediating light-induced retinal degeneration. These findings suggest that the expression and function of RPE65 and rhodopsin need to be coordinately controlled to sustain normal vision and to protect the retina from photodamage. However, the mechanism controlling the development of the retinal visual system remains poorly understood. Here, we show that deficiency in ciliary neurotrophic factor (CNTF) up-regulates the levels of rod and cone opsins accompanied by an increase in the thickness of the outer nuclear layers and the lengths of cone and rod outer segments in the mouse retina. Moreover, retinoid isomerase activity, expression levels of RPE65 and lecithin:retinol acyltransferase (LRAT), which synthesizes the RPE65 substrate, were also significantly increased in the Cntf -/- RPE. Rod a-wave and cone b-wave amplitudes of electroretinograms were increased in Cntf -/- mice, but rod b-wave amplitudes were unchanged compared with those in WT mice. Up-regulated RPE65 and LRAT levels accelerated both the visual cycle rate and recovery rate of rod light sensitivity in Cntf -/- mice. Of note, rods and cones in Cntf -/- mice exhibited hypersusceptibility to light-induced degeneration. These results indicate that CNTF is a common extracellular factor that prevents excessive production of opsins, the photoreceptor outer segments, and 11-cis-retinal to protect rods and cones from photodamage.
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Affiliation(s)
- Songhua Li
- From the Neuroscience Center of Excellence and
| | - Kota Sato
- From the Neuroscience Center of Excellence and
| | - William C Gordon
- From the Neuroscience Center of Excellence and.,Department of Ophthalmology, Louisiana State University School of Medicine, New Orleans, Louisiana 70112 and
| | - Michael Sendtner
- the Institute of Clinical Neurobiology, University Hospital Würzburg, D-97078 Würzburg, Germany
| | - Nicolas G Bazan
- From the Neuroscience Center of Excellence and.,Department of Ophthalmology, Louisiana State University School of Medicine, New Orleans, Louisiana 70112 and
| | - Minghao Jin
- From the Neuroscience Center of Excellence and .,Department of Ophthalmology, Louisiana State University School of Medicine, New Orleans, Louisiana 70112 and
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12
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Racz B, Varadi A, Kong J, Allikmets R, Pearson PG, Johnson G, Cioffi CL, Petrukhin K. A non-retinoid antagonist of retinol-binding protein 4 rescues phenotype in a model of Stargardt disease without inhibiting the visual cycle. J Biol Chem 2018; 293:11574-11588. [PMID: 29871924 DOI: 10.1074/jbc.ra118.002062] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 06/01/2018] [Indexed: 12/11/2022] Open
Abstract
A primary pathological defect in the heritable eye disorder Stargardt disease is excessive accumulation of cytotoxic lipofuscin bisretinoids in the retina. Age-dependent accumulation of lipofuscin in the retinal pigment epithelium (RPE) matches the age-dependent increase in the incidence of the atrophic (dry) form of age-related macular degeneration (AMD) and therefore may be one of several pathogenic factors contributing to AMD progression. Lipofuscin bisretinoid synthesis in the retina depends on the influx of serum retinol from the circulation into the RPE. Formation of the tertiary retinol-binding protein 4 (RBP4)-transthyretin-retinol complex in the serum is required for this influx. Herein, we report the pharmacological effects of the non-retinoid RBP4 antagonist, BPN-14136. BPN-14136 dosing in the Abca4-/- mouse model of increased lipofuscinogenesis significantly reduced serum RBP4 levels and inhibited bisretinoid synthesis, and this inhibition correlated with a partial reduction in visual cycle retinoids such as retinaldehydes serving as bisretinoid precursors. BPN-14136 administration at doses inducing maximal serum RBP4 reduction did not produce changes in the rate of the visual cycle, consistent with minimal changes in dark adaptation. Abca4-/- mice exhibited dysregulation of the complement system in the retina, and BPN-14136 administration normalized the retinal levels of proinflammatory complement cascade components such as complement factors D and H, C-reactive protein, and C3. We conclude that BPN-14136 has several beneficial characteristics, combining inhibition of bisretinoid synthesis and reduction in retinaldehydes with normalization of the retinal complement system. BPN-14136, or a similar compound, may be a promising drug candidate to manage Stargardt disease and dry AMD.
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Affiliation(s)
- Boglarka Racz
- Department of Ophthalmology, Columbia University, New York, New York 10032
| | - Andras Varadi
- Department of Ophthalmology, Columbia University, New York, New York 10032
| | - Jian Kong
- Department of Ophthalmology, Columbia University, New York, New York 10032
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, New York 10032; Department of Pathology and Cell Biology, Columbia University, New York, New York 10032
| | - Paul G Pearson
- Pearson Pharma Partners, Westlake Village, California 91361
| | | | - Christopher L Cioffi
- Departments of Basic and Clinical Sciences and Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York 12208
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13
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Shin Y, Moiseyev G, Petrukhin K, Cioffi CL, Muthuraman P, Takahashi Y, Ma JX. A novel RPE65 inhibitor CU239 suppresses visual cycle and prevents retinal degeneration. Biochim Biophys Acta Mol Basis Dis 2018; 1864:2420-2429. [PMID: 29684583 DOI: 10.1016/j.bbadis.2018.04.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 04/02/2018] [Accepted: 04/17/2018] [Indexed: 01/25/2023]
Abstract
The retinoid visual cycle is an ocular retinoid metabolism specifically dedicated to support vertebrate vision. The visual cycle serves not only to generate light-sensitive visual chromophore 11-cis-retinal, but also to clear toxic byproducts of normal visual cycle (i.e. all-trans-retinal and its condensation products) from the retina, ensuring both the visual function and the retinal health. Unfortunately, various conditions including genetic predisposition, environment and aging may attribute to a functional decline of the all-trans-retinal clearance. To combat all-trans-retinal mediated retinal degeneration, we sought to slow down the retinoid influx from the RPE by inhibiting the visual cycle with a small molecule. The present study describes identification of CU239, a novel non-retinoid inhibitor of RPE65, a key enzyme in the visual cycle. Our data demonstrated that CU239 selectively inhibited isomerase activity of RPE65, with IC50 of 6 μM. Further, our results indicated that CU239 inhibited RPE65 via competition with its substrate all-trans-retinyl ester. Mice with systemic injection of CU239 exhibited delayed chromophore regeneration after light bleach, and conferred a partial protection of the retina against injury from high intensity light. Taken together, CU239 is a potent visual cycle modulator and may have a therapeutic potential for retinal degeneration.
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Affiliation(s)
- Younghwa Shin
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, United States
| | - Gennadiy Moiseyev
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, United States.
| | - Konstantin Petrukhin
- Department of Ophthalmology, Columbia University, New York, NY 10032, United States
| | - Christopher L Cioffi
- Departments of Basic & Clinical Sciences and Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, NY 12208, United States
| | - Parthasarathy Muthuraman
- Departments of Basic & Clinical Sciences and Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, NY 12208, United States
| | - Yusuke Takahashi
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, United states
| | - Jian-Xing Ma
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, United States
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14
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Schur RM, Gao S, Yu G, Chen Y, Maeda A, Palczewski K, Lu ZR. New GABA modulators protect photoreceptor cells from light-induced degeneration in mouse models. FASEB J 2018; 32:3289-3300. [PMID: 29401616 DOI: 10.1096/fj.201701250r] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
No clinically approved therapies are currently available that prevent the onset of photoreceptor death in retinal degeneration. Signaling between retinal neurons is regulated by the release and uptake of neurotransmitters, wherein GABA is the main inhibitory neurotransmitter. In this work, novel 3-chloropropiophenone derivatives and the clinical anticonvulsants tiagabine and vigabatrin were tested to modulate GABA signaling and protect against light-induced retinal degeneration. Abca4-/-Rdh8-/- mice, an accelerated model of retinal degeneration, were exposed to intense light after prophylactic injections of one of these compounds. Imaging and functional assessments of the retina indicated that these compounds successfully protected photoreceptor cells from degeneration to maintain a full-visual-field response. Furthermore, these compounds demonstrated a strong safety profile in wild-type mice and did not compromise visual function or damage the retina, despite repeated administration. These results indicate that modulating inhibitory GABA signaling can offer prophylactic protection against light-induced retinal degeneration.-Schur, R. M., Gao, S., Yu, G., Chen, Y., Maeda, A., Palczewski, K., Lu, Z.-R. New GABA modulators protect photoreceptor cells from light-induced degeneration in mouse models.
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Affiliation(s)
- Rebecca M Schur
- Case Center for Biomolecular Engineering, Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, Ohio, USA
| | - Songqi Gao
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Guanping Yu
- Case Center for Biomolecular Engineering, Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, Ohio, USA
| | - Yu Chen
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Akiko Maeda
- Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Zheng-Rong Lu
- Case Center for Biomolecular Engineering, Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, Ohio, USA
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15
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Sears AE, Bernstein PS, Cideciyan AV, Hoyng C, Charbel Issa P, Palczewski K, Rosenfeld PJ, Sadda S, Schraermeyer U, Sparrow JR, Washington I, Scholl HPN. Towards Treatment of Stargardt Disease: Workshop Organized and Sponsored by the Foundation Fighting Blindness. Transl Vis Sci Technol 2017; 6:6. [PMID: 28920007 PMCID: PMC5599228 DOI: 10.1167/tvst.6.5.6] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 07/11/2017] [Indexed: 01/13/2023] Open
Abstract
Accumulation of fluorescent metabolic byproducts of the visual (retinoid) cycle is associated with photoreceptor and retinal pigment epithelial cell death in both Stargardt disease and atrophic (nonneovascular) age-related macular degeneration (AMD). As a consequence of this observation, small molecular inhibitors of enzymes in the visual cycle were recently tested in clinical trials as a strategy to protect the retina and retinal pigment epithelium in patients with atrophic AMD. To address the clinical translational needs for therapies aimed at both diseases, a workshop organized by the Foundation Fighting Blindness was hosted by the Department of Pharmacology at Case Western Reserve University on February 17, 2017, at the Tinkham Veale University Center, Cleveland, OH, USA. Invited speakers highlighted recent advances in the understanding of the pathophysiology of Stargardt disease, in terms of its clinical characterization and the development of endpoints for clinical trials, and discussed the comparability of therapeutic strategies between atrophic age-related macular degeneration (AMD) and Stargardt disease. Investigators speculated that reducing the concentrations of visual cycle precursor substances and/or their byproducts may provide valid therapeutic options for the treatment of Stargardt disease. Here we review the workshop's presentations in the context of published literature to help shape the aims of ongoing research endeavors and aid the development of therapies for Stargardt disease.
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Affiliation(s)
- Avery E Sears
- Department of Pharmacology, School of Medicine, Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, OH, USA
| | | | - Artur V Cideciyan
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Carel Hoyng
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Peter Charbel Issa
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, and the Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, OH, USA
| | - Philip J Rosenfeld
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - SriniVas Sadda
- Doheny Image Reading Center, Doheny Eye Institute, Los Angeles, CA, USA
| | - Ulrich Schraermeyer
- Institute of Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Janet R Sparrow
- Edward S. Harkness Eye Institute, Columbia University Medical Center, New York, NY, USA
| | - Ilyas Washington
- Edward S. Harkness Eye Institute, Columbia University Medical Center, New York, NY, USA
| | - Hendrik P N Scholl
- Department of Ophthalmology, University of Basel, Basel, Switzerland.,Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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16
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Sahu B, Maeda A. Retinol Dehydrogenases Regulate Vitamin A Metabolism for Visual Function. Nutrients 2016; 8:E746. [PMID: 27879662 PMCID: PMC5133129 DOI: 10.3390/nu8110746] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 11/13/2016] [Accepted: 11/16/2016] [Indexed: 02/07/2023] Open
Abstract
The visual system produces visual chromophore, 11-cis-retinal from dietary vitamin A, all-trans-retinol making this vitamin essential for retinal health and function. These metabolic events are mediated by a sequential biochemical process called the visual cycle. Retinol dehydrogenases (RDHs) are responsible for two reactions in the visual cycle performed in retinal pigmented epithelial (RPE) cells, photoreceptor cells and Müller cells in the retina. RDHs in the RPE function as 11-cis-RDHs, which oxidize 11-cis-retinol to 11-cis-retinal in vivo. RDHs in rod photoreceptor cells in the retina work as all-trans-RDHs, which reduce all-trans-retinal to all-trans-retinol. Dysfunction of RDHs can cause inherited retinal diseases in humans. To facilitate further understanding of human diseases, mouse models of RDHs-related diseases have been carefully examined and have revealed the physiological contribution of specific RDHs to visual cycle function and overall retinal health. Herein we describe the function of RDHs in the RPE and the retina, particularly in rod photoreceptor cells, their regulatory properties for retinoid homeostasis and future therapeutic strategy for treatment of retinal diseases.
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Affiliation(s)
- Bhubanananda Sahu
- Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4965, USA.
| | - Akiko Maeda
- Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4965, USA.
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106-4965, USA.
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17
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Abstract
Recent progress in molecular understanding of the retinoid cycle in mammalian retina stems from painstaking biochemical reconstitution studies supported by natural or engineered animal models with known genetic lesions and studies of humans with specific genetic blinding diseases. Structural and membrane biology have been used to detect critical retinal enzymes and proteins and their substrates and ligands, placing them in a cellular context. These studies have been supplemented by analytical chemistry methods that have identified small molecules by their spectral characteristics, often in conjunction with the evaluation of models of animal retinal disease. It is from this background that rational therapeutic interventions to correct genetic defects or environmental insults are identified. Thus, most presently accepted modulators of the retinoid cycle already have demonstrated promising results in animal models of retinal degeneration. These encouraging signs indicate that some human blinding diseases can be alleviated by pharmacological interventions.
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Affiliation(s)
- Philip D Kiser
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106 ; Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio 44106
| | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
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18
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Silvaroli JA, Arne JM, Chelstowska S, Kiser PD, Banerjee S, Golczak M. Ligand Binding Induces Conformational Changes in Human Cellular Retinol-binding Protein 1 (CRBP1) Revealed by Atomic Resolution Crystal Structures. J Biol Chem 2016; 291:8528-40. [PMID: 26900151 DOI: 10.1074/jbc.m116.714535] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Indexed: 12/31/2022] Open
Abstract
Important in regulating the uptake, storage, and metabolism of retinoids, cellular retinol-binding protein 1 (CRBP1) is essential for trafficking vitamin A through the cytoplasm. However, the molecular details of ligand uptake and targeted release by CRBP1 remain unclear. Here we report the first structure of CRBP1 in a ligand-free form as well as ultra-high resolution structures of this protein bound to either all-trans-retinol or retinylamine, the latter a therapeutic retinoid that prevents light-induced retinal degeneration. Superpositioning of human apo- and holo-CRBP1 revealed major differences within segments surrounding the entrance to the retinoid-binding site. These included α-helix II and hairpin turns between β-strands βC-βD and βE-βF as well as several side chains, such as Phe-57, Tyr-60, and Ile-77, that change their orientations to accommodate the ligand. Additionally, we mapped hydrogen bond networks inside the retinoid-binding cavity and demonstrated their significance for the ligand affinity. Analyses of the crystallographic B-factors indicated several regions with higher backbone mobility in the apoprotein that became more rigid upon retinoid binding. This conformational flexibility of human apo-CRBP1 facilitates interaction with the ligands, whereas the more rigid holoprotein structure protects the labile retinoid moiety during vitamin A transport. These findings suggest a mechanism of induced fit upon ligand binding by mammalian cellular retinol-binding proteins.
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Affiliation(s)
| | | | - Sylwia Chelstowska
- From the Department of Pharmacology and the Laboratory of Hematology and Flow Cytometry, Department of Hematology, Military Institute of Medicine, Warsaw 04-141, Poland
| | - Philip D Kiser
- From the Department of Pharmacology and the Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio 44106
| | - Surajit Banerjee
- the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, and the Northeastern Collaborative Access Team, Argonne National Laboratory, Argonne, Illinois 60439
| | - Marcin Golczak
- From the Department of Pharmacology and the Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106,
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19
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Stiles M, Moiseyev GP, Budda ML, Linens A, Brush RS, Qi H, White GL, Wolf RF, Ma JX, Floyd R, Anderson RE, Mandal NA. PBN (Phenyl-N-Tert-Butylnitrone)-Derivatives Are Effective in Slowing the Visual Cycle and Rhodopsin Regeneration and in Protecting the Retina from Light-Induced Damage. PLoS One 2015; 10:e0145305. [PMID: 26694648 PMCID: PMC4687940 DOI: 10.1371/journal.pone.0145305] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 12/02/2015] [Indexed: 11/18/2022] Open
Abstract
A2E and related toxic molecules are part of lipofuscin found in the retinal pigment epithelial (RPE) cells in eyes affected by Stargardt's disease, age-related macular degeneration (AMD), and other retinal degenerations. A novel therapeutic approach for treating such degenerations involves slowing down the visual cycle, which could reduce the amount of A2E in the RPE. This can be accomplished by inhibiting RPE65, which produces 11-cis-retinol from all-trans-retinyl esters. We recently showed that phenyl-N-tert-butylnitrone (PBN) inhibits RPE65 enzyme activity in RPE cells. In this study we show that like PBN, certain PBN-derivatives (PBNDs) such as 4-F-PBN, 4-CF3-PBN, 3,4-di-F-PBN, and 4-CH3-PBN can inhibit RPE65 and synthesis of 11-cis-retinol in in vitro assays using bovine RPE microsomes. We further demonstrate that systemic (intraperitoneal, IP) administration of these PBNDs protect the rat retina from light damage. Electroretinography (ERG) and histological analysis showed that rats treated with PBNDs retained ~90% of their photoreceptor cells compared to a complete loss of function and 90% loss of photoreceptors in the central retina in rats treated with vehicle/control injections. Topically applied PBN and PBNDs also significantly slowed the rate of the visual cycle in mouse and baboon eyes. One hour dark adaptation resulted in 75-80% recovery of bleachable rhodopsin in control/vehicle treated mice. Eye drops of 5% 4-CH3-PBN were most effective, inhibiting the regeneration of bleachable rhodopsin significantly (60% compared to vehicle control). In addition, a 10% concentration of PBN and 5% concentration of 4-CH3-PBN in baboon eyes inhibited the visual cycle by 60% and by 30%, respectively. We have identified a group of PBN related nitrones that can reach the target tissue (RPE) by systemic and topical application and slow the rate of rhodopsin regeneration and therefore the visual cycle in mouse and baboon eyes. PBNDs can also protect the rat retina from light damage. There is potential in developing these compounds as preventative therapeutics for the treatment of human retinal degenerations in which the accumulation of lipofuscin may be pathogenic.
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Affiliation(s)
- Megan Stiles
- Department of Ophthalmology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States of America
| | - Gennadiy P. Moiseyev
- Department of Physiology, OUHSC, Oklahoma City, Oklahoma, United States of America
| | - Madeline L. Budda
- Department of Cell Biology, OUHSC, Oklahoma City, Oklahoma, United States of America
| | - Annette Linens
- Department of Ophthalmology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States of America
| | - Richard S. Brush
- Department of Ophthalmology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States of America
| | - Hui Qi
- Department of Ophthalmology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States of America
| | - Gary L. White
- Department of Pathology, OUHSC, Oklahoma City, Oklahoma, United States of America
| | - Roman F. Wolf
- Department of Pathology, OUHSC, Oklahoma City, Oklahoma, United States of America
| | - Jian-xing Ma
- Department of Physiology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Department of Endocrinology and Diabetes, OUHSC, Oklahoma City, Oklahoma, United States of America
| | - Robert Floyd
- Experimental Therapeutics, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
| | - Robert E. Anderson
- Department of Ophthalmology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Department of Pathology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States of America
| | - Nawajes A. Mandal
- Department of Ophthalmology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Department of Cell Biology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Department of Endocrinology and Diabetes, OUHSC, Oklahoma City, Oklahoma, United States of America
- Oklahoma Center for Neuroscience, OUHSC, Oklahoma City, Oklahoma, United States of America
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States of America
- * E-mail:
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20
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Phase ii, randomized, placebo-controlled, 90-day study of emixustat hydrochloride in geographic atrophy associated with dry age-related macular degeneration. Retina 2015; 35:1173-83. [PMID: 25932553 DOI: 10.1097/iae.0000000000000606] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
PURPOSE This study assessed the safety, tolerability, and pharmacodynamics of emixustat hydrochloride (ACU-4429), a novel visual cycle modulator, in subjects with geographic atrophy associated with dry age-related macular degeneration. METHODS Subjects were randomly assigned to oral emixustat (2, 5, 7, or 10 mg once daily) or placebo (3:1 ratio) for 90 days. Recovery of rod photoreceptor sensitivity after a photobleach was measured by electroretinography. Safety evaluations included analysis of adverse events and ophthalmic examinations. RESULTS Seventy-two subjects (54 emixustat and 18 placebo) were evaluated. Emixustat suppressed rod photoreceptor sensitivity in a dose-dependent manner. Suppression plateaued by Day 14 and was reversible within 7 days to 14 days after drug cessation. Most systemic adverse events were not considered treatment related. Dose-related ocular adverse events (chromatopsia, 57% emixustat vs. 17% placebo and delayed dark adaptation, 48% emixustat vs. 6% placebo) were mild to moderate in severity, and the majority resolved on study or within 7 days to 14 days after study drug cessation. Reversibility of these adverse events with long-term administration, however, is undetermined. CONCLUSION In this Phase II study, emixustat produced a dose-dependent reversible effect on rod function that is consistent with the proposed mechanism of action. These results support further testing of emixustat for the treatment of geographic atrophy associated with dry age-related macular degeneration.
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21
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Schur RM, Sheng L, Sahu B, Yu G, Gao S, Yu X, Maeda A, Palczewski K, Lu ZR. Manganese-Enhanced MRI for Preclinical Evaluation of Retinal Degeneration Treatments. Invest Ophthalmol Vis Sci 2015. [PMID: 26225634 DOI: 10.1167/iovs.15-16522] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
PURPOSE Apply manganese-enhanced magnetic resonance imaging (MEMRI) to assess ion channel activity and structure of retinas from mice subject to light-induced retinal degeneration treated with prophylactic agents. METHODS Abca4(-/-)Rdh8(-/-) double knockout mice with and without prophylactic retinylamine (Ret-NH2) treatment were illuminated with strong light. Manganese-enhanced MRI was used to image the retina 2 hours after intravitreous injection of MnCl2 into one eye. Contrast-enhanced MRIs of the retina and vitreous humor in each experimental group were assessed and correlated with the treatment. Findings were compared with standard structural and functional assessments of the retina by optical coherence tomography (OCT), histology, and electroretinography (ERG). RESULTS Manganese-enhanced MRI contrast in the retina was high in nonilluminated and illuminated Ret-NH2-treated mice, whereas no enhancement was evident in the retina of the light-illuminated mice without Ret-NH2 treatment (P < 0.0005). A relatively high signal enhancement was also observed in the vitreous humor of mice treated with Ret-NH2. Strong MEMRI signal enhancement in the retinas of mice treated with retinylamine was correlated with their structural integrity and function evidenced by OCT, histology, and a strong ERG light response. CONCLUSIONS Manganese-enhanced MRI has the potential to assess the response of the retina to prophylactic treatment based on the measurement of ion channel activity. This approach could be used as a complementary tool in preclinical development of new prophylactic therapies for retinopathies.
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Affiliation(s)
- Rebecca M Schur
- Department of Biomedical Engineering School of Engineering, Case Western Reserve University, Cleveland, Ohio, United States
| | - Li Sheng
- Department of Biomedical Engineering School of Engineering, Case Western Reserve University, Cleveland, Ohio, United States
| | - Bhubanananda Sahu
- Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
| | - Guanping Yu
- Department of Biomedical Engineering School of Engineering, Case Western Reserve University, Cleveland, Ohio, United States
| | - Songqi Gao
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
| | - Xin Yu
- Department of Biomedical Engineering School of Engineering, Case Western Reserve University, Cleveland, Ohio, United States
| | - Akiko Maeda
- Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States 3Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
| | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
| | - Zheng-Rong Lu
- Department of Biomedical Engineering School of Engineering, Case Western Reserve University, Cleveland, Ohio, United States
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22
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Graded gene expression changes determine phenotype severity in mouse models of CRX-associated retinopathies. Genome Biol 2015; 16:171. [PMID: 26324254 PMCID: PMC4556057 DOI: 10.1186/s13059-015-0732-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 07/28/2015] [Indexed: 01/28/2023] Open
Abstract
Background Mutations in the cone-rod-homeobox protein CRX are typically associated with dominant blinding retinopathies with variable age of onset and severity. Five well-characterized mouse models carrying different Crx mutations show a wide range of disease phenotypes. To determine if the phenotype variability correlates with distinct changes in CRX target gene expression, we perform RNA-seq analyses on three of these models and compare the results with published data. Results Despite dramatic phenotypic differences between the three models tested, graded expression changes in shared sets of genes are detected. Phenotype severity correlates with the down-regulation of genes encoding key rod and cone phototransduction proteins. Interestingly, in increasingly severe mouse models, the transcription of many rod-enriched genes decreases decrementally, whereas that of cone-enriched genes increases incrementally. Unlike down-regulated genes, which show a high degree of CRX binding and dynamic epigenetic profiles in normal retinas, the up-regulated cone-enriched genes do not correlate with direct activity of CRX, but instead likely reflect a change in rod cell-fate integrity. Furthermore, these analyses describe the impact of minor gene expression changes on the phenotype, as two mutants showed marginally distinguishable expression patterns but huge phenotypic differences, including distinct mechanisms of retinal degeneration. Conclusions Our results implicate a threshold effect of gene expression level on photoreceptor function and survival, highlight the importance of CRX in photoreceptor subtype development and maintenance, and provide a molecular basis for phenotype variability in CRX-associated retinopathies. Electronic supplementary material The online version of this article (doi:10.1186/s13059-015-0732-z) contains supplementary material, which is available to authorized users.
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23
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Cioffi CL, Racz B, Freeman EE, Conlon MP, Chen P, Stafford DG, Schwarz DMC, Zhu L, Kitchen DB, Barnes KD, Dobri N, Michelotti E, Cywin CL, Martin WH, Pearson PG, Johnson G, Petrukhin K. Bicyclic [3.3.0]-Octahydrocyclopenta[c]pyrrolo Antagonists of Retinol Binding Protein 4: Potential Treatment of Atrophic Age-Related Macular Degeneration and Stargardt Disease. J Med Chem 2015; 58:5863-88. [PMID: 26181715 DOI: 10.1021/acs.jmedchem.5b00423] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Antagonists of retinol-binding protein 4 (RBP4) impede ocular uptake of serum all-trans retinol (1) and have been shown to reduce cytotoxic bisretinoid formation in the retinal pigment epithelium (RPE), which is associated with the pathogenesis of both dry age-related macular degeneration (AMD) and Stargardt disease. Thus, these agents show promise as a potential pharmacotherapy by which to stem further neurodegeneration and concomitant vision loss associated with geographic atrophy of the macula. We previously disclosed the discovery of a novel series of nonretinoid RBP4 antagonists, represented by bicyclic [3.3.0]-octahydrocyclopenta[c]pyrrolo analogue 4. We describe herein the utilization of a pyrimidine-4-carboxylic acid fragment as a suitable isostere for the anthranilic acid appendage of 4, which led to the discovery of standout antagonist 33. Analogue 33 possesses exquisite in vitro RBP4 binding affinity and favorable drug-like characteristics and was found to reduce circulating plasma RBP4 levels in vivo in a robust manner (>90%).
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Affiliation(s)
| | - Boglarka Racz
- §Department of Ophthalmology, Columbia University Medical Center, New York, New York 10032, United States
| | | | | | | | | | | | | | | | | | - Nicoleta Dobri
- §Department of Ophthalmology, Columbia University Medical Center, New York, New York 10032, United States
| | - Enrique Michelotti
- #National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Charles L Cywin
- ○National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - William H Martin
- ⊥WHM Consulting LLC, 111 Sterling City Road, Lyme, Connecticut 06371, United States
| | - Paul G Pearson
- ∥iCuraVision LLC, 31194 La Baya Drive, Suite 101, Westlake Village, California 91362, United States
| | - Graham Johnson
- ∥iCuraVision LLC, 31194 La Baya Drive, Suite 101, Westlake Village, California 91362, United States
| | - Konstantin Petrukhin
- §Department of Ophthalmology, Columbia University Medical Center, New York, New York 10032, United States
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24
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Liu H, Tang J, Du Y, Lee CA, Golczak M, Muthusamy A, Antonetti DA, Veenstra AA, Amengual J, von Lintig J, Palczewski K, Kern TS. Retinylamine Benefits Early Diabetic Retinopathy in Mice. J Biol Chem 2015; 290:21568-79. [PMID: 26139608 DOI: 10.1074/jbc.m115.655555] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Indexed: 12/12/2022] Open
Abstract
Recent evidence suggests an important role for outer retinal cells in the pathogenesis of diabetic retinopathy (DR). Here we investigated the effect of the visual cycle inhibitor retinylamine (Ret-NH2) on the development of early DR lesions. Wild-type (WT) C57BL/6J mice (male, 2 months old when diabetes was induced) were made diabetic with streptozotocin, and some were given Ret-NH2 once per week. Lecithin-retinol acyltransferase (LRAT)-deficient mice and P23H mutant mice were similarly studied. Mice were euthanized after 2 (WT and Lrat(-/-)) and 8 months (WT) of study to assess vascular histopathology, accumulation of albumin, visual function, and biochemical and physiological abnormalities in the retina. Non-retinal effects of Ret-NH2 were examined in leukocytes treated in vivo. Superoxide generation and expression of inflammatory proteins were significantly increased in retinas of mice diabetic for 2 or 8 months, and the number of degenerate retinal capillaries and accumulation of albumin in neural retina were significantly increased in mice diabetic for 8 months compared with nondiabetic controls. Administration of Ret-NH2 once per week inhibited capillary degeneration and accumulation of albumin in the neural retina, significantly reducing diabetes-induced retinal superoxide and expression of inflammatory proteins. Superoxide generation also was suppressed in Lrat(-/-) diabetic mice. Leukocytes isolated from diabetic mice treated with Ret-NH2 caused significantly less cytotoxicity to retinal endothelial cells ex vivo than did leukocytes from control diabetics. Administration of Ret-NH2 once per week significantly inhibited the pathogenesis of lesions characteristic of early DR in diabetic mice. The visual cycle constitutes a novel target for inhibition of DR.
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Affiliation(s)
| | - Jie Tang
- From the Departments of Medicine and
| | | | | | - Marcin Golczak
- Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106
| | - Arivalagan Muthusamy
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan 48105, and
| | - David A Antonetti
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan 48105, and
| | | | - Jaume Amengual
- Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106
| | | | | | - Timothy S Kern
- From the Departments of Medicine and Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106, Veterans Affairs Medical Center, Cleveland, Ohio 44106
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25
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Zhang J, Kiser PD, Badiee M, Palczewska G, Dong Z, Golczak M, Tochtrop GP, Palczewski K. Molecular pharmacodynamics of emixustat in protection against retinal degeneration. J Clin Invest 2015; 125:2781-94. [PMID: 26075817 DOI: 10.1172/jci80950] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/12/2015] [Indexed: 01/24/2023] Open
Abstract
Emixustat is a visual cycle modulator that has entered clinical trials as a treatment for age-related macular degeneration (AMD). This molecule has been proposed to inhibit the visual cycle isomerase RPE65, thereby slowing regeneration of 11-cis-retinal and reducing production of retinaldehyde condensation byproducts that may be involved in AMD pathology. Previously, we reported that all-trans-retinal (atRAL) is directly cytotoxic and that certain primary amine compounds that transiently sequester atRAL via Schiff base formation ameliorate retinal degeneration. Here, we have shown that emixustat stereoselectively inhibits RPE65 by direct active site binding. However, we detected the presence of emixustat-atRAL Schiff base conjugates, indicating that emixustat also acts as a retinal scavenger, which may contribute to its therapeutic effects. Using agents that lack either RPE65 inhibitory activity or the capacity to sequester atRAL, we assessed the relative importance of these 2 modes of action in protection against retinal phototoxicity in mice. The atRAL sequestrant QEA-B-001-NH2 conferred protection against phototoxicity without inhibiting RPE65, whereas an emixustat derivative incapable of atRAL sequestration was minimally protective, despite direct inhibition of RPE65. These data indicate that atRAL sequestration is an essential mechanism underlying the protective effects of emixustat and related compounds against retinal phototoxicity. Moreover, atRAL sequestration should be considered in the design of next-generation visual cycle modulators.
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26
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Bavik C, Henry SH, Zhang Y, Mitts K, McGinn T, Budzynski E, Pashko A, Lieu KL, Zhong S, Blumberg B, Kuksa V, Orme M, Scott I, Fawzi A, Kubota R. Visual Cycle Modulation as an Approach toward Preservation of Retinal Integrity. PLoS One 2015; 10:e0124940. [PMID: 25970164 PMCID: PMC4430241 DOI: 10.1371/journal.pone.0124940] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 03/19/2015] [Indexed: 01/10/2023] Open
Abstract
Increased exposure to blue or visible light, fluctuations in oxygen tension, and the excessive accumulation of toxic retinoid byproducts places a tremendous amount of stress on the retina. Reduction of visual chromophore biosynthesis may be an effective method to reduce the impact of these stressors and preserve retinal integrity. A class of non-retinoid, small molecule compounds that target key proteins of the visual cycle have been developed. The first candidate in this class of compounds, referred to as visual cycle modulators, is emixustat hydrochloride (emixustat). Here, we describe the effects of emixustat, an inhibitor of the visual cycle isomerase (RPE65), on visual cycle function and preservation of retinal integrity in animal models. Emixustat potently inhibited isomerase activity in vitro (IC50 = 4.4 nM) and was found to reduce the production of visual chromophore (11-cis retinal) in wild-type mice following a single oral dose (ED50 = 0.18 mg/kg). Measure of drug effect on the retina by electroretinography revealed a dose-dependent slowing of rod photoreceptor recovery (ED50 = 0.21 mg/kg) that was consistent with the pattern of visual chromophore reduction. In albino mice, emixustat was shown to be effective in preventing photoreceptor cell death caused by intense light exposure. Pre-treatment with a single dose of emixustat (0.3 mg/kg) provided a ~50% protective effect against light-induced photoreceptor cell loss, while higher doses (1–3 mg/kg) were nearly 100% effective. In Abca4-/- mice, an animal model of excessive lipofuscin and retinoid toxin (A2E) accumulation, chronic (3 month) emixustat treatment markedly reduced lipofuscin autofluorescence and reduced A2E levels by ~60% (ED50 = 0.47 mg/kg). Finally, in the retinopathy of prematurity rodent model, treatment with emixustat during the period of ischemia and reperfusion injury produced a ~30% reduction in retinal neovascularization (ED50 = 0.46mg/kg). These data demonstrate the ability of emixustat to modulate visual cycle activity and reduce pathology associated with various biochemical and environmental stressors in animal models. Other attributes of emixustat, such as oral bioavailability and target specificity make it an attractive candidate for clinical development in the treatment of retinal disease.
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Affiliation(s)
- Claes Bavik
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Susan Hayes Henry
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Yan Zhang
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Kyoko Mitts
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Tim McGinn
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Ewa Budzynski
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Andriy Pashko
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Kuo Lee Lieu
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Sheng Zhong
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Bruce Blumberg
- University of California, Irvine, School of Biological Sciences, 4351 Natural Sciences II, Irvine, California 92697, United States of America
| | - Vladimir Kuksa
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Mark Orme
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Ian Scott
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Ahmad Fawzi
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Ryo Kubota
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
- * E-mail:
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27
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Perusek L, Maeda A, Maeda T. Supplementation with vitamin a derivatives to rescue vision in animal models of degenerative retinal diseases. Methods Mol Biol 2015; 1271:345-362. [PMID: 25697534 DOI: 10.1007/978-1-4939-2330-4_22] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The perception of light begins when photons reach retinal tissue located at the back of the eye and photoisomerize the visual chromophore 11-cis-retinal to all-trans-retinal within photoreceptor cells. Isomerization of 11-cis-retinal activates the protein rhodopsin located in photoreceptor outer segments, thereby inducing a phototransduction cascade leading to visual perception. To maintain vision, 11-cis-retinal is regenerated in the retinal pigmented epithelium (RPE) via the visual cycle and delivered back to the photoreceptor cells where it may again bind to rhodopsin. Distinct pathological mechanisms have been observed to contribute to inherited retinal degenerative diseases including severe delay in 11-cis-retinal regeneration and delayed clearance of all-trans-retinal, which leads to the accumulation of harmful retinoid by-products. In the last decade, our group has conducted several proof-of-concept (POC) studies with retinoid derivatives aimed at developing treatments for retinal degenerative diseases caused by an impaired visual cycle. Here, we will introduce experimental procedures, which have been developed for POC studies involving retinoid biology.
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Affiliation(s)
- Lindsay Perusek
- Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Adelbert Road 2085, Cleveland, OH, 44106, USA
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28
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Zhang J, Dong Z, Mundla SR, Hu XE, Seibel W, Papoian R, Palczewski K, Golczak M. Expansion of first-in-class drug candidates that sequester toxic all-trans-retinal and prevent light-induced retinal degeneration. Mol Pharmacol 2014; 87:477-91. [PMID: 25538117 DOI: 10.1124/mol.114.096560] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
All-trans-retinal, a retinoid metabolite naturally produced upon photoreceptor light activation, is cytotoxic when present at elevated levels in the retina. To lower its toxicity, two experimentally validated methods have been developed involving inhibition of the retinoid cycle and sequestration of excess of all-trans-retinal by drugs containing a primary amine group. We identified the first-in-class drug candidates that transiently sequester this metabolite or slow down its production by inhibiting regeneration of the visual chromophore, 11-cis-retinal. Two enzymes are critical for retinoid recycling in the eye. Lecithin:retinol acyltransferase (LRAT) is the enzyme that traps vitamin A (all-trans-retinol) from the circulation and photoreceptor cells to produce the esterified substrate for retinoid isomerase (RPE65), which converts all-trans-retinyl ester into 11-cis-retinol. Here we investigated retinylamine and its derivatives to assess their inhibitor/substrate specificities for RPE65 and LRAT, mechanisms of action, potency, retention in the eye, and protection against acute light-induced retinal degeneration in mice. We correlated levels of visual cycle inhibition with retinal protective effects and outlined chemical boundaries for LRAT substrates and RPE65 inhibitors to obtain critical insights into therapeutic properties needed for retinal preservation.
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Affiliation(s)
- Jianye Zhang
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio (J.Z., Z.D., K.P., M.G.); Sreeni Laboratories Private Limited, Telangana, India (S.R.M.); Aroz Technologies LLC, Cincinnati, Ohio (X.E.H.); and Drug Discovery Center, College of Medicine, University of Cincinnati, Cincinnati, Ohio (W.S., R.P.)
| | - Zhiqian Dong
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio (J.Z., Z.D., K.P., M.G.); Sreeni Laboratories Private Limited, Telangana, India (S.R.M.); Aroz Technologies LLC, Cincinnati, Ohio (X.E.H.); and Drug Discovery Center, College of Medicine, University of Cincinnati, Cincinnati, Ohio (W.S., R.P.)
| | - Sreenivasa Reddy Mundla
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio (J.Z., Z.D., K.P., M.G.); Sreeni Laboratories Private Limited, Telangana, India (S.R.M.); Aroz Technologies LLC, Cincinnati, Ohio (X.E.H.); and Drug Discovery Center, College of Medicine, University of Cincinnati, Cincinnati, Ohio (W.S., R.P.)
| | - X Eric Hu
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio (J.Z., Z.D., K.P., M.G.); Sreeni Laboratories Private Limited, Telangana, India (S.R.M.); Aroz Technologies LLC, Cincinnati, Ohio (X.E.H.); and Drug Discovery Center, College of Medicine, University of Cincinnati, Cincinnati, Ohio (W.S., R.P.)
| | - William Seibel
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio (J.Z., Z.D., K.P., M.G.); Sreeni Laboratories Private Limited, Telangana, India (S.R.M.); Aroz Technologies LLC, Cincinnati, Ohio (X.E.H.); and Drug Discovery Center, College of Medicine, University of Cincinnati, Cincinnati, Ohio (W.S., R.P.)
| | - Ruben Papoian
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio (J.Z., Z.D., K.P., M.G.); Sreeni Laboratories Private Limited, Telangana, India (S.R.M.); Aroz Technologies LLC, Cincinnati, Ohio (X.E.H.); and Drug Discovery Center, College of Medicine, University of Cincinnati, Cincinnati, Ohio (W.S., R.P.)
| | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio (J.Z., Z.D., K.P., M.G.); Sreeni Laboratories Private Limited, Telangana, India (S.R.M.); Aroz Technologies LLC, Cincinnati, Ohio (X.E.H.); and Drug Discovery Center, College of Medicine, University of Cincinnati, Cincinnati, Ohio (W.S., R.P.)
| | - Marcin Golczak
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio (J.Z., Z.D., K.P., M.G.); Sreeni Laboratories Private Limited, Telangana, India (S.R.M.); Aroz Technologies LLC, Cincinnati, Ohio (X.E.H.); and Drug Discovery Center, College of Medicine, University of Cincinnati, Cincinnati, Ohio (W.S., R.P.)
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29
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Visual Cycle Suppression via Patching in Central Serous Chorioretinopathy. Ophthalmology 2014; 121:2502-4.e1. [DOI: 10.1016/j.ophtha.2014.06.038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 06/24/2014] [Indexed: 11/19/2022] Open
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30
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Yu G, Wu X, Ayat N, Maeda A, Gao SQ, Golczak M, Palczewski K, Lu ZR. Multifunctional PEG retinylamine conjugate provides prolonged protection against retinal degeneration in mice. Biomacromolecules 2014; 15:4570-8. [PMID: 25390360 PMCID: PMC4261990 DOI: 10.1021/bm501352s] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
![]()
A polyethylene glycol (PEG) retinylamine
(Ret-NH2) conjugate
PEG-GFL-NH-Ret with a glycine-phenylalanine-leucine (GFL) spacer was
synthesized for controlled oral delivery of Ret-NH2 to
treat retinal degenerative diseases, including Stargardt disease (STGD)
and age-related macular degeneration (AMD). The peptide spacer was
introduced for sustained release of the drug by digestive enzymes
in the gastrointestinal tract. The pharmacokinetics experiments showed
that the PEG conjugate could control the sustained drug release after
oral administration and had much lower nonspecific liver drug accumulation
than the free drug in wild-type female C57BL mice. In the mean time,
the conjugate maintained the same concentration of Ret-NH2 in the eye as the free drug. Also, PEG-GFL-NH-Ret at a Ret-NH2 equivalent dose of 25 mg/kg produced complete protection
of Abca4–/–Rdh8–/– mouse retinas against light-induced
retinal degeneration for 3 days after oral administration, as revealed
by OCT retina imaging, whereas free Ret-NH2 did not provide
any protection under identical conditions. The polymer conjugate PEG-GFL-NH-Ret
has great potential for controlled delivery of Ret-NH2 to
the eye for effective protection against retinal degenerative diseases.
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Affiliation(s)
- Guanping Yu
- Department of Biomedical Engineering, School of Engineering, §Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, and ∥Department of Ophthalmology, School of Medicine, Case Western Reserve University , Cleveland, Ohio 44140, United States
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31
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Phase 1, dose-ranging study of emixustat hydrochloride (ACU-4429), a novel visual cycle modulator, in healthy volunteers. Retina 2014; 34:603-9. [PMID: 24056528 DOI: 10.1097/01.iae.0000434565.80060.f8] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND Emixustat hydrochloride (formerly ACU-4429) is a nonretinoid compound with a unique mode of action in the retinal pigment epithelium, where it modulates the biosynthesis of visual chromophore through its effect on retinal pigment epithelium-specific 65 kDa protein isomerase. This study provides clinicians with a background for understanding the pharmacokinetics and safety profile of orally administered emixustat. METHODS This randomized, double-masked, placebo-controlled Phase 1b study evaluated the pharmacokinetics, tolerability, and safety of a 14-day course of oral emixustat (5, 10, 20, 30, or 40 mg) or placebo (3:1 ratio) once daily in healthy volunteers. RESULTS A total of 40 subjects were enrolled (mean age, 38 years; 75% male). Emixustat (n = 30) was rapidly absorbed (median T(max), 3.0-5 hours) and readily eliminated (mean t(1/2), 4.6-7.9 hours), and mean C(max) and AUC(0-24) generally increased in proportion to dose. No significant accumulation of emixustat was observed with multiple-dose administration. Ocular adverse events occurred in 67% of the subjects who received emixustat; all were considered mild and resolved after study completion. Systemic adverse events were minimal. CONCLUSION Oral emixustat was safe and well tolerated when administered once daily for 14 days with minimal systemic adverse events reported. These data support evaluation of emixustat in subjects with geographic atrophy associated with dry age-related macular degeneration.
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32
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Tolentino MJ, Dennrick A, John E, Tolentino MS. Drugs in Phase II clinical trials for the treatment of age-related macular degeneration. Expert Opin Investig Drugs 2014; 24:183-99. [PMID: 25243494 DOI: 10.1517/13543784.2015.961601] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION The clinical development of anti-VEGF therapies for the treatment of exudative age-related macular degeneration (wet AMD) has revolutionized ophthalmology. Indeed, it has provided clinicians and patients with treatments that lessen visual loss from in a disease that once was uniformly blinding. Although blindness is yet to be eradicated from AMD, repeated intraocular anti-VEGF injections are required to preserve a patient's vision. Therefore, further advances in this field are necessary. AREAS COVERED This review provides an overview of the agents that are in mid-stage phase trials for both exudative (wet AMD) and nonexudative macular degeneration (dry AMD). For wet AMD, new agents intend to enhance efficacy, develop alternative delivery such as eye drops, investigate alternate targets and construct sustained release strategies. For advanced dry AMD, the goal is to develop a strategy to slow or stop progressive loss of retinal tissue seen in geographic atrophy, the hallmark of advanced dry AMD. EXPERT OPINION It is important to develop better more sensitive biomarkers, validating different approvable clinical trial endpoints and stratifying patients on their genetic polymorphisms. These developments should help to progress the already rapidly developing field of macular degeneration therapy.
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Affiliation(s)
- Michael John Tolentino
- University of Central Florida, College of Medicine , 6850 Lake Nona Blvd. Orlando, FL 32827 , USA
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33
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Cioffi CL, Dobri N, Freeman EE, Conlon MP, Chen P, Stafford DG, Schwarz DMC, Golden KC, Zhu L, Kitchen DB, Barnes KD, Racz B, Qin Q, Michelotti E, Cywin CL, Martin WH, Pearson PG, Johnson G, Petrukhin K. Design, synthesis, and evaluation of nonretinoid retinol binding protein 4 antagonists for the potential treatment of atrophic age-related macular degeneration and Stargardt disease. J Med Chem 2014; 57:7731-57. [PMID: 25210858 PMCID: PMC4174998 DOI: 10.1021/jm5010013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
![]()
Accumulation of lipofuscin in the
retina is associated with pathogenesis
of atrophic age-related macular degeneration and Stargardt disease.
Lipofuscin bisretinoids (exemplified by N-retinylidene-N-retinylethanolamine) seem to mediate lipofuscin toxicity.
Synthesis of lipofuscin bisretinoids depends on the influx of retinol
from serum to the retina. Compounds antagonizing the retinol-dependent
interaction of retinol-binding protein 4 (RBP4) with transthyretin
in the serum would reduce serum RBP4 and retinol and inhibit bisretinoid
formation. We recently showed that A1120 (3), a potent
carboxylic acid based RBP4 antagonist, can significantly reduce lipofuscin
bisretinoid formation in the retinas of Abca4–/– mice. As part of the NIH
Blueprint Neurotherapeutics Network project we undertook the in vitro exploration to identify novel conformationally flexible and constrained
RBP4 antagonists with improved potency and metabolic stability. We
also demonstrate that upon acute and chronic dosing in rats, 43, a potent cyclopentyl fused pyrrolidine antagonist, reduced
circulating plasma RBP4 protein levels by approximately 60%.
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Affiliation(s)
- Christopher L Cioffi
- Department of Medicinal Chemistry, Albany Molecular Research, Inc. , East Campus, C-Wing, Rensselaer, New York 12144, United States
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Querques G, Rosenfeld PJ, Cavallero E, Borrelli E, Corvi F, Querques L, Bandello FM, Zarbin MA. Treatment of Dry Age-Related Macular Degeneration. Ophthalmic Res 2014; 52:107-15. [DOI: 10.1159/000363187] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 04/12/2014] [Indexed: 11/19/2022]
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Palczewska G, Dong Z, Golczak M, Hunter JJ, Williams DR, Alexander NS, Palczewski K. Noninvasive two-photon microscopy imaging of mouse retina and retinal pigment epithelium through the pupil of the eye. Nat Med 2014; 20:785-9. [PMID: 24952647 PMCID: PMC4087080 DOI: 10.1038/nm.3590] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 11/12/2013] [Indexed: 12/11/2022]
Abstract
Two-photon excitation microscopy can image retinal molecular processes in vivo. Intrinsically fluorescent retinyl esters in subcellular structures called retinosomes are an integral part of the visual chromophore regeneration pathway. Fluorescent condensation products of all-trans-retinal accumulate in the eye with age and are also associated with age-related macular degeneration (AMD). Here, we report repetitive, dynamic imaging of these compounds in live mice through the pupil of the eye. By leveraging advanced adaptive optics, we developed a data acquisition algorithm that permitted the identification of retinosomes and condensation products in the retinal pigment epithelium by their characteristic localization, spectral properties and absence in genetically modified or drug-treated mice. This imaging approach has the potential to detect early molecular changes in retinoid metabolism that trigger light- and AMD-induced retinal defects and to assess the effectiveness of treatments for these conditions.
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Affiliation(s)
| | | | - Marcin Golczak
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
| | - Jennifer J Hunter
- 1] Center for Visual Science, University of Rochester, Rochester, New York, USA. [2] Flaum Eye Institute, University of Rochester, Rochester, New York, USA. [3] Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
| | - David R Williams
- 1] Center for Visual Science, University of Rochester, Rochester, New York, USA. [2] The Institute of Optics, University of Rochester, Rochester, New York, USA
| | - Nathan S Alexander
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
| | - Krzysztof Palczewski
- 1] Polgenix, Cleveland, Ohio, USA. [2] Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
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Wu X, Yu G, Luo C, Maeda A, Zhang N, Sun D, Zhou Z, Puntel A, Palczewski K, Lu ZR. Synthesis and evaluation of a nanoglobular dendrimer 5-aminosalicylic Acid conjugate with a hydrolyzable schiff base spacer for treating retinal degeneration. ACS NANO 2014; 8:153-61. [PMID: 24350906 PMCID: PMC4060971 DOI: 10.1021/nn4054107] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Biocompatible dendrimers with well-defined nanosizes are increasingly being used as carriers for drug delivery. 5-Aminosalicylic acid (5-ASA) is an FDA-approved therapeutic agent recently found effective in treating retinal degeneration of animal models. Here, a water-soluble dendrimer conjugate of 5-ASA (AGFB-ASA) was designed to treat such retinal degeneration. The drug was conjugated to a generation 2 (G2) lysine dendrimer with a silsesquioxane core (nanoglobule) by using a hydrolyzable Schiff base spacer. Incubation of nanoglobular G2 dendrimer conjugates containing a 4-formylbenzoate (FB) Schiff base spacer in pH 7.4 phosphate buffers at 37 °C gradually released 5-ASA. Drug release from the dendrimer conjugate was significantly slower than from the low molecular weight free Schiff base of 5-ASA (FB-ASA). 5-ASA release from the dendrimer conjugate was dependent on steric hindrance around the spacer. After intraperitoneal injection, the nanoglobular 5-ASA conjugate provided more effective 7-day protection against light-induced retinal degeneration at a reduced dose than free 5-ASA in Abca4(-/-)Rdh8(-/-) mice. The dendrimer 5-ASA conjugate with a degradable spacer could be a good candidate for controlled delivery of 5-ASA to the eye for treatment of retinal degeneration.
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Affiliation(s)
- Xueming Wu
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, Ohio, USA
| | - Guanping Yu
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, Ohio, USA
| | - Chengcai Luo
- Ningbo Institute of Technology, Zhejiang University, Ningbo, Zhejiang, China
| | - Akiko Maeda
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Ophthalmology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Ning Zhang
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Da Sun
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, Ohio, USA
| | - Zhuxian Zhou
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, Ohio, USA
| | - Anthony Puntel
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, Ohio, USA
| | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Zheng-Rong Lu
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, Ohio, USA
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Álvarez R, Vaz B, Gronemeyer H, de Lera ÁR. Functions, therapeutic applications, and synthesis of retinoids and carotenoids. Chem Rev 2013; 114:1-125. [PMID: 24266866 DOI: 10.1021/cr400126u] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Rosana Álvarez
- Departamento de Química Orgánica, Centro de Investigación Biomédica (CINBIO), and Instituto de Investigación Biomédica de Vigo (IBIV), Universidade de Vigo , 36310 Vigo, Spain
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Nowak-Sliwinska P, van den Bergh H, Sickenberg M, Koh AHC. Photodynamic therapy for polypoidal choroidal vasculopathy. Prog Retin Eye Res 2013; 37:182-99. [PMID: 24140257 DOI: 10.1016/j.preteyeres.2013.09.003] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 09/23/2013] [Accepted: 09/27/2013] [Indexed: 01/05/2023]
Affiliation(s)
- Patrycja Nowak-Sliwinska
- Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland; University Hospital (CHUV), Lausanne, Switzerland.
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Investigation of oral fenretinide for treatment of geographic atrophy in age-related macular degeneration. Retina 2013; 33:498-507. [PMID: 23023528 DOI: 10.1097/iae.0b013e318265801d] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Excessive accumulation of retinol-based toxins has been implicated in the pathogenesis of geographic atrophy (GA). Fenretinide, an orally available drug that reduces retinol delivery to the eye through antagonism of serum retinol-binding protein (RBP), was used in a 2-year trial to determine whether retinol reduction would be effective in the management of geographic atrophy. METHODS The efficacy of fenretinide (100 and 300 mg daily, orally) to slow lesion growth in geographic atrophy patients was examined in a 2-year, placebo-controlled double-masked trial that enrolled 246 patients at 30 clinical sites in the United States. RESULTS Fenretinide treatment produced dose-dependent reversible reductions in serum RBP-retinol that were associated with trends in reduced lesion growth rates. Patients in the 300 mg group who achieved serum retinol levels of ≤ 1 μM (≤ 2 mg/dL RBP) showed a mean reduction of 0.33 mm in the yearly lesion growth rate compared with subjects in the placebo group (1.70 mm/year vs. 2.03 mm/year, respectively, P = 0.1848). Retinol-binding protein reductions <2 mg/dL correlated with further reductions in lesion growth rates (r = 0.478). Fenretinide treatment also reduced the incidence of choroidal neovascularization (approximately 45% reduction in incidence rate in the combined fenretinide groups vs. placebo, P = 0.0606). This therapeutic effect was not dose dependent and is consistent with anti-angiogenic properties of fenretinide, which have been observed in other disease states. CONCLUSION The findings of this study and the established safety profile of fenretinide in chronic dosing regimens warrant further study of fenretinide in the treatment of geographic atrophy.
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Sparrow JR, Blonska A, Flynn E, Duncker T, Greenberg JP, Secondi R, Ueda K, Delori FC. Quantitative fundus autofluorescence in mice: correlation with HPLC quantitation of RPE lipofuscin and measurement of retina outer nuclear layer thickness. Invest Ophthalmol Vis Sci 2013; 54:2812-20. [PMID: 23548623 DOI: 10.1167/iovs.12-11490] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
PURPOSE Our study was conducted to establish procedures and protocols for quantitative autofluorescence (qAF) measurements in mice, and to report changes in qAF, A2E bisretinoid concentration, and outer nuclear layer (ONL) thickness in mice of different genotypes and age. METHODS Fundus autofluorescence (AF) images (55° lens, 488 nm excitation) were acquired in albino Abca4(-/-), Abca4(+/-), and Abca4(+/+) mice (ages 2-12 months) with a confocal scanning laser ophthalmoscope (cSLO). Gray levels (GLs) in each image were calibrated to an internal fluorescence reference. The bisretinoid A2E was measured by quantitative high performance liquid chromatography (HPLC). Histometric analysis of ONL thicknesses was performed. RESULTS The Bland-Altman coefficient of repeatability (95% confidence interval) was ±18% for between-session qAF measurements. Mean qAF values increased with age (2-12 months) in all groups of mice. qAF was approximately 2-fold higher in Abca4(-/-) mice than in Abca4(+/+) mice and approximately 20% higher in heterozygous mice. HPLC measurements of the lipofuscin fluorophore A2E also revealed age-associated increases, and the fold difference between Abca4(-/-) and wild-type mice was more pronounced (approximately 3-4-fold) than measurable by qAF. Moreover, A2E levels declined after 8 months of age, a change not observed with qAF. The decline in A2E levels in the Abca4(-/-) mice corresponded to reduced photoreceptor cell viability as reflected in ONL thinning beginning at 8 months of age. CONCLUSIONS The qAF method enables measurement of in vivo lipofuscin and the detection of genotype and age-associated differences. The use of this approach has the potential to aid in understanding retinal disease processes and will facilitate preclinical studies.
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Affiliation(s)
- Janet R Sparrow
- Department of Ophthalmology, Columbia University, New York, New York 10032, USA.
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Fatty acid transport protein 4 (FATP4) prevents light-induced degeneration of cone and rod photoreceptors by inhibiting RPE65 isomerase. J Neurosci 2013; 33:3178-89. [PMID: 23407971 DOI: 10.1523/jneurosci.2428-12.2013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Although rhodopsin is essential for sensing light for vision, it also mediates light-induced apoptosis of photoreceptors in mouse. RPE65, which catalyzes isomerization of all-trans retinyl fatty acid esters to 11-cis-retinol (11cROL) in the visual cycle, controls the rhodopsin regeneration rate and photoreceptor susceptibility to light-induced degeneration. Mutations in RPE65 have been linked to blindness in affected children. Despite such importance, the mechanism that regulates RPE65 function remains unclear. Through unbiased expression screening of a bovine retinal pigment epithelium (RPE) cDNA library, we have identified elongation of very long-chain fatty acids-like 1 (ELOVL1) and fatty acid transport protein 4 (FATP4), which each have very long-chain fatty acid acyl-CoA synthetase (VLCFA-ACS) activity, as negative regulators of RPE65. We found that the VLCFA derivative lignoceroyl (C24:0)-CoA inhibited synthesis of 11cROL, whereas palmitoyl (C16:0)-CoA promoted synthesis of 11cROL. We further found that competition of FATP4 with RPE65 for the substrate of RPE65 was also involved in the mechanisms by which FATP4 inhibits synthesis of 11cROL. FATP4 was predominantly expressed in RPE, and the FATP4-deficient RPE showed significantly higher isomerase activity. Consistent with these results, the regeneration rate of 11-cis-retinaldehyde and the recovery rate for rod light sensitivity were faster in FATP4-deficient mice than wild-type mice. Moreover, FATP4-deficient mice displayed increased accumulation of the cytotoxic all-trans retinaldehyde and hypersusceptibility to light-induced photoreceptor degeneration. Our findings demonstrate that ELOVL1, FATP4, and their products comprise the regulatory elements of RPE65 and play important roles in protecting photoreceptors from degeneration induced by light damage.
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Dobri N, Qin Q, Kong J, Yamamoto K, Liu Z, Moiseyev G, Ma JX, Allikmets R, Sparrow JR, Petrukhin K. A1120, a nonretinoid RBP4 antagonist, inhibits formation of cytotoxic bisretinoids in the animal model of enhanced retinal lipofuscinogenesis. Invest Ophthalmol Vis Sci 2013; 54:85-95. [PMID: 23211825 DOI: 10.1167/iovs.12-10050] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
PURPOSE Excessive accumulation of lipofuscin is associated with pathogenesis of atrophic age-related macular degeneration (AMD) and Stargardt disease. Pharmacologic inhibition of the retinol-induced interaction of retinol-binding protein 4 (RBP4) with transthyretin (TTR) in the serum may decrease the uptake of serum retinol to the retina and reduce formation of lipofuscin bisretinoids. We evaluated in vitro and in vivo properties of the new nonretinoid RBP4 antagonist, A1120. METHODS RBP4 binding potency, ability to antagonize RBP4-TTR interaction, and compound specificity were analyzed for A1120 and for the prototypic RBP4 antagonist fenretinide. A1120 ability to inhibit RPE65-mediated isomerohydrolase activity was assessed in the RPE microsomes. The in vivo effect of A1120 administration on serum RBP4, visual cycle retinoids, lipofuscin bisretinoids, and retinal visual function was evaluated using a combination of biochemical and electrophysiologic techniques. RESULTS In comparison to fenretinide, A1120 did not act as a RARα agonist, while exhibiting superior in vitro potency in RBP4 binding and RBP4-TTR interaction assays. A1120 did not inhibit isomerohydrolase activity in the RPE microsomes. A1120 dosing in mice induced 75% reduction in serum RBP4, which correlated with reduction in visual cycle retinoids and ocular levels of lipofuscin fluorophores. A1120 dosing did not induce changes in kinetics of dark adaptation. CONCLUSIONS A1120 significantly reduces accumulation of lipofuscin bisretinoids in the Abca4(-/-) animal model. This activity correlates with reduction in serum RBP4 and visual cycle retinoids confirming the mechanism of action for A1120. In contrast to fenretinide, A1120 does not act as a RARα agonist indicating a more favorable safety profile for this nonretinoid compound.
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Affiliation(s)
- Nicoleta Dobri
- Department of Ophthalmology, Columbia University, New York, New York 10032, USA
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Miller JW. Age-related macular degeneration revisited--piecing the puzzle: the LXIX Edward Jackson memorial lecture. Am J Ophthalmol 2013; 155:1-35.e13. [PMID: 23245386 DOI: 10.1016/j.ajo.2012.10.018] [Citation(s) in RCA: 180] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 10/19/2012] [Accepted: 10/23/2012] [Indexed: 12/11/2022]
Abstract
PURPOSE To present the current understanding of age-related macular degeneration (AMD) pathogenesis, based on clinical evidence, epidemiologic data, histopathologic examination, and genetic data; to provide an update on current and emerging therapies; and to propose an integrated model of the pathogenesis of AMD. DESIGN Review of published clinical and experimental studies. METHODS Analysis and synthesis of clinical and experimental data. RESULTS We are closer to a complete understanding of the pathogenesis of AMD, having progressed from clinical observations to epidemiologic observations and clinical pathologic correlation. More recently, modern genetic and genomic studies have facilitated the exploration of molecular pathways. It seems that AMD is a complex disease that results from the interaction of genetic susceptibility with aging and environmental factors. Disease progression also seems to be driven by a combination of genetic and environmental factors. CONCLUSIONS Therapies based on pathophysiologic features have changed the paradigm for treating neovascular AMD. With improved understanding of the underlying genetic susceptibility, we can identify targets to halt early disease and to prevent progression and vision loss.
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Petrukhin K. Pharmacological inhibition of lipofuscin accumulation in the retina as a therapeutic strategy for dry AMD treatment. ACTA ACUST UNITED AC 2013; 10:e11-e20. [PMID: 25152755 DOI: 10.1016/j.ddstr.2013.05.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Age-related macular degeneration (AMD) is the leading cause of blindness in the western world. There is no FDA-approved treatment for the most prevalent dry (atrophic) form of AMD. Photoreceptor degeneration in dry AMD is triggered by abnormalities in the retinal pigment epithelium (RPE). It has been suggested that excessive accumulation of fluorescent lipofuscin pigment in the RPE represents an important pathogenic factor in etiology and progression of dry AMD. Cytotoxic lipofuscin bisretinoids, such as A2E, are formed in the retina in a non-enzymatic way from visual cycle retinoids. Inhibition of toxic bisretinoid production in the retina seems to be a sound treatment strategy for dry AMD. In this review we discuss the following classes of pharmacological treatments inhibiting lipofuscin bisretinoid formation in the retina: direct inhibitors of key visual cycle enzymes, RBP4 antagonists, primary amine-containing aldehyde traps, and deuterated analogs of vitamin A.
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Gao SQ, Maeda T, Okano K, Palczewski K. A microparticle/hydrogel combination drug-delivery system for sustained release of retinoids. Invest Ophthalmol Vis Sci 2012; 53:6314-23. [PMID: 22918645 PMCID: PMC3465014 DOI: 10.1167/iovs.12-10279] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Revised: 07/18/2012] [Accepted: 08/20/2012] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To design and develop a drug-delivery system containing a combination of poly(D,L-lactide-co-glycolide) (PLGA) microparticles and alginate hydrogel for sustained release of retinoids to treat retinal blinding diseases that result from an inadequate supply of retinol and generation of 11-cis-retinal. METHODS To study drug release in vivo, either the drug-loaded microparticle-hydrogel combination was injected subcutaneously or drug-loaded microparticles were injected intravitreally into Lrat(-/-) mice. Orally administered 9-cis-retinoids were used for comparison and drug concentrations in plasma were determined by HPLC. Electroretinography (ERG) and both chemical and histologic analyses were used to evaluate drug effects on visual function and morphology. RESULTS Lrat(-/-) mice demonstrated sustained drug release from the microparticle/hydrogel combination that lasted 4 weeks after subcutaneous injection. Drug concentrations in plasma of the control group treated with the same oral dose rose to higher levels for 6-7 hours but then dropped markedly by 24 hours. Significantly increased ERG responses and a markedly improved retinal pigmented epithelium (RPE)-rod outer segment (ROS) interface were observed after subcutaneous injection of the drug-loaded delivery combination. Intravitreal injection of just 2% of the systemic dose of drug-loaded microparticles provided comparable therapeutic efficacy. CONCLUSIONS Sustained release of therapeutic levels of 9-cis-retinoids was achieved in Lrat(-/-) mice by subcutaneous injection in a microparticle/hydrogel drug-delivery system. Both subcutaneous and intravitreal injections of drug-loaded microparticles into Lrat(-/-) mice improved visual function and retinal structure.
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Affiliation(s)
| | - Tadao Maeda
- Ophthalmology, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Kiichiro Okano
- Ophthalmology, School of Medicine, Case Western Reserve University, Cleveland, Ohio
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Girmens JF, Sahel JA, Marazova K. Dry age-related macular degeneration: A currently unmet clinical need. Intractable Rare Dis Res 2012; 1:103-14. [PMID: 25343081 PMCID: PMC4204600 DOI: 10.5582/irdr.2012.v1.3.103] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 07/25/2012] [Indexed: 01/08/2023] Open
Abstract
Age-related macular degeneration (AMD) is a leading cause of severe visual impairment and disability in older people worldwide. Although considerable advances in the management of the neovascular form of AMD have been made in the last decade, no therapy is yet available for the advanced dry form of AMD (geographic atrophy). This review focuses on current trends in the development of new therapies targeting specific pathophysiological pathways of dry AMD. Increased understanding of the complex mechanisms that underlie dry AMD will help to address this largely unmet clinical need.
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Affiliation(s)
- Jean-François Girmens
- French National Institute of Health and Medical Research, Paris, France
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, Paris, France
- Address correspondence to: Dr. Jean-François Girmens, Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, 28 rue de Charenton, 75571 Paris Cedex 12, France. E-mail:
| | - José-Alain Sahel
- French National Institute of Health and Medical Research, Paris, France
- French Academy of Sciences, Paris, France
| | - Katia Marazova
- French National Institute of Health and Medical Research, Paris, France
- National Center for Scientific Research, Paris, France
- Dr. Katia Marazova, Institut de la Vision, 17 rue Moreau, 75012 Paris, France. E-mail:
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Jain GK, Warsi MH, Nirmal J, Garg V, Pathan SA, Ahmad FJ, Khar RK. Therapeutic stratagems for vascular degenerative disorders of the posterior eye. Drug Discov Today 2012; 17:748-59. [DOI: 10.1016/j.drudis.2012.03.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 01/27/2012] [Accepted: 03/20/2012] [Indexed: 12/23/2022]
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Abstract
Accumulation of all-trans-retinal (all-trans-RAL), reactive vitamin A aldehyde, is one of the key factors in initiating retinal photodamage. This photodamage is characterized by progressive retinal cell death evoked by light exposure in both an acute and chronic fashion. Photoactivated rhodopsin releases all-trans-RAL, which is subsequently transported by ATP-binding cassette transporter 4 and reduced to all-trans-retinol by all-trans-retinol dehydrogenases located in photoreceptor cells. Any interruptions in the clearing of all-trans-RAL in the photoreceptors can cause an accumulation of this reactive aldehyde and its toxic condensation products. This accumulation may result in the manifestation of retinal dystrophy including human retinal degenerative diseases such as Stargardt's disease and age-related macular degeneration. Herein, we discuss the mechanisms of all-trans-RAL clearance in photoreceptor cells by sequential enzymatic reactions, the visual (retinoid) cycle, and potential molecular pathways of retinal photodamage. We also review recent imaging technologies to monitor retinal health status as well as novel therapeutic strategies preventing all-trans-RAL-associated retinal photodamage.
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Affiliation(s)
- Tadao Maeda
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, USA
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Berry DC, Noy N. Signaling by vitamin A and retinol-binding protein in regulation of insulin responses and lipid homeostasis. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1821:168-76. [PMID: 21782034 PMCID: PMC3204314 DOI: 10.1016/j.bbalip.2011.07.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Revised: 05/31/2011] [Accepted: 07/06/2011] [Indexed: 12/25/2022]
Abstract
Vitamin A, retinol, circulates in blood bound to serum retinol binding protein (RBP) and is transported into cells by a membrane protein termed stimulated by retinoic acid 6 (STRA6). It was reported that serum levels of RBP are elevated in obese rodents and humans, and that increased level of RBP in blood causes insulin resistance. A molecular mechanism by which RBP can exert such an effect is suggested by the recent discovery that STRA6 is not only a vitamin A transporter but also functions as a surface signaling receptor. Binding of RBP-ROH to STRA6 induces the phosphorylation of a tyrosine residue in the receptor C-terminus, thereby activating a JAK/STAT signaling cascade. Consequently, in STRA6-expressing cells such as adipocytes, RBP-ROH induces the expression of STAT target genes, including SOCS3, which suppresses insulin signaling, and PPARγ, which enhances lipid accumulation. RBP-retinol thus joins the myriad of cytokines, growth factors and hormones which regulate gene transcription by activating cell surface receptors that signal through activation of Janus kinases and their associated transcription factors STATs. This article is part of a Special Issue entitled Retinoid and Lipid Metabolism.
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Affiliation(s)
- Daniel C Berry
- Department of Pharmacology and Nutrition, Case Western Reserve University School of Medicine, Cleveland, OH 44106-4695, USA
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Maeda A, Golczak M, Chen Y, Okano K, Kohno H, Shiose S, Ishikawa K, Harte W, Palczewska G, Maeda T, Palczewski K. Primary amines protect against retinal degeneration in mouse models of retinopathies. Nat Chem Biol 2011; 8:170-8. [PMID: 22198730 PMCID: PMC3518042 DOI: 10.1038/nchembio.759] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Accepted: 10/07/2011] [Indexed: 12/31/2022]
Abstract
Vertebrate vision is initiated by photoisomerization of the visual pigment chromophore 11-cis-retinal and is maintained by continuous regeneration of this retinoid through a series of reactions termed the retinoid cycle. However, toxic side reaction products, especially those involving reactive aldehyde groups of the photoisomerized product, all-trans-retinal, can cause severe retinal pathology. Here we lowered peak concentrations of free all-trans-retinal with primary amine-containing Food and Drug Administration (FDA)-approved drugs that did not inhibit chromophore regeneration in mouse models of retinal degeneration. Schiff base adducts between all-trans-retinal and these amines were identified by MS. Adducts were observed in mouse eyes only when an experimental drug protected the retina from degeneration in both short-term and long-term treatment experiments. This study demonstrates a molecular basis of all-trans-retinal-induced retinal pathology and identifies an assemblage of FDA-approved compounds with protective effects against this pathology in a mouse model that shows features of Stargardt's disease and age-related retinal degeneration.
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Affiliation(s)
- Akiko Maeda
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, USA
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