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Bruno F, Errico S, Pace S, Nawrozkij MB, Mkrtchyan AS, Guida F, Maisto R, Olgaç A, D'Amico M, Maione S, De Rosa M, Banoglu E, Werz O, Fiorentino A, Filosa R. Structural insight into the optimization of ethyl 5-hydroxybenzo[g]indol-3-carboxylates and their bioisosteric analogues as 5-LO/m-PGES-1 dual inhibitors able to suppress inflammation. Eur J Med Chem 2018; 155:946-960. [PMID: 30015253 DOI: 10.1016/j.ejmech.2018.05.041] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 05/23/2018] [Accepted: 05/25/2018] [Indexed: 12/13/2022]
Abstract
The release of pro-inflammatory mediators, such as prostaglandines (PGs) and leukotrienes (LTs), arising from the arachidonic acid (AA) cascade, play a crucial role in initiating, maintaining, and regulating inflammatory processes. New dual inhibitors of 5-lipoxygenase (5-LO) and microsomal prostaglandin E2 synthase-1 (mPGES-1), that block, at the same time, the formation of PGE2 and LTs, are currently emerged as a highly interesting drug candidates for better pharmacotherapie of inflammation-related disorders. Following our previous studies, we here performed a detailed structure-based design of benzo[g]indol-3-carboxylate derivatives, disclosing several new key factors that affect both enzyme activity. Ethyl 2-(3,4-dichlorobenzyl)-5-hydroxy-1H-benzo[g]indole-3-carboxylate (4b, RAF-01) and ethyl 2-(3,4-dichlorophenyl)-5-hydroxy-1H-benzo[g]indole-3-carboxylate (7h, RAF-02) emerged as the most active compounds of the series. Additionally, together with selected structure based analogues, both derivatives displayed significant in vivo anti-inflammatory properties. In conclusion, modeling and experimental studies lead to the discovery of new candidate compounds prone to further developments as multi-target inhibitors of the inflammatory pathway.
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Affiliation(s)
- Ferdinando Bruno
- Università degli Studi della Campania Luigi Vanvitelli, Department of Experimental Medicine, Naples, Italy
| | - Suann Errico
- Università degli Studi della Campania Luigi Vanvitelli, Department of Experimental Medicine, Naples, Italy; Department of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, Friedrich-Schiller-University of Jena, Philosophenweg 14, Jena, Germany
| | - Simona Pace
- Department of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, Friedrich-Schiller-University of Jena, Philosophenweg 14, Jena, Germany
| | - Maxim B Nawrozkij
- Volgograd State Technical University, Organic Chemistry Department, Lenin Avenue 28, Russian Federation
| | - Arthur S Mkrtchyan
- Volgograd State Technical University, Organic Chemistry Department, Lenin Avenue 28, Russian Federation
| | - Francesca Guida
- Università degli Studi della Campania Luigi Vanvitelli, Department of Experimental Medicine, Naples, Italy
| | - Rosa Maisto
- Università degli Studi della Campania Luigi Vanvitelli, Department of Experimental Medicine, Naples, Italy
| | - Abdurrahman Olgaç
- Gazi University, Faculty of Pharmacy, Department of Pharmaceutical Chemistry, Yenimahalle, Ankara, 06330, Turkey
| | - Michele D'Amico
- Università degli Studi della Campania Luigi Vanvitelli, Department of Experimental Medicine, Naples, Italy
| | - Sabatino Maione
- Università degli Studi della Campania Luigi Vanvitelli, Department of Experimental Medicine, Naples, Italy
| | - Mario De Rosa
- Università degli Studi della Campania Luigi Vanvitelli, Department of Experimental Medicine, Naples, Italy
| | - Erden Banoglu
- Gazi University, Faculty of Pharmacy, Department of Pharmaceutical Chemistry, Yenimahalle, Ankara, 06330, Turkey
| | - Oliver Werz
- Department of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, Friedrich-Schiller-University of Jena, Philosophenweg 14, Jena, Germany
| | - Antonio Fiorentino
- Università della Campania Luigi Vanvitelli, Department of Environmental Biological and Pharmaceutical Sciences and Technologies, Naples, Italy
| | - Rosanna Filosa
- Università degli Studi della Campania Luigi Vanvitelli, Department of Experimental Medicine, Naples, Italy; Consorzio Sannio Tech, Appia Str, Apollosa, BN, 82030, Italy; Institute of Food Sciences, National Research Council, Roma Str. 64, Avellino, 83100, Italy.
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2
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Gong Y, Fu Z, Liegl R, Chen J, Hellström A, Smith LEH. ω-3 and ω-6 long-chain PUFAs and their enzymatic metabolites in neovascular eye diseases. Am J Clin Nutr 2017; 106:16-26. [PMID: 28515072 PMCID: PMC5486202 DOI: 10.3945/ajcn.117.153825] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 04/18/2017] [Indexed: 01/01/2023] Open
Abstract
Neovascular eye diseases, including retinopathy of prematurity, diabetic retinopathy, and age-related macular degeneration, threaten the visual health of children and adults. Current treatment options, including anti-vascular endothelial growth factor therapy and laser retinal photocoagulation, have limitations and are associated with adverse effects; therefore, the identification of additional therapies is highly desirable. Both clinical and experimental studies show that dietary ω-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFAs) reduce retinal and choroidal angiogenesis. The ω-3 LC-PUFA metabolites from 2 groups of enzymes, cyclooxygenases and lipoxygenases, inhibit [and the ω-6 (n-6) LC-PUFA metabolites promote] inflammation and angiogenesis. However, both of the ω-3 and the ω-6 lipid products of cytochrome P450 oxidase 2C promote neovascularization in both the retina and choroid, which suggests that inhibition of this pathway might be beneficial. This review summarizes our current understanding of the roles of ω-3 and ω-6 LC-PUFAs and their enzymatic metabolites in neovascular eye diseases.
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Affiliation(s)
- Yan Gong
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA; and
| | - Zhongjie Fu
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA; and
| | - Raffael Liegl
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA; and
| | - Jing Chen
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA; and
| | - Ann Hellström
- Department of Ophthalmology, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Lois EH Smith
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA; and
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3
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Subramanian P, Mendez EF, Becerra SP. A Novel Inhibitor of 5-Lipoxygenase (5-LOX) Prevents Oxidative Stress-Induced Cell Death of Retinal Pigment Epithelium (RPE) Cells. Invest Ophthalmol Vis Sci 2017; 57:4581-8. [PMID: 27635633 PMCID: PMC5033602 DOI: 10.1167/iovs.15-19039] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
PURPOSE 5-Lipoxygenase (5-LOX) oxygenates arachidonic acid to form 5-hydroperoxyeicosatetraenoic acid, which is further converted into biologically detrimental leukotrienes, such as leukotriene B4 (LTB4). The RPE and retina express the PNPLA2 gene for pigment epithelium-derived factor receptor (PEDF-R), a lipase involved in cell survival. The purpose here was to investigate the role of PEDF-R on the 5-LOX pathway in oxidative stress of RPE. METHODS Lipoxygenase activity assays were performed with soybean and potato lipoxygenase. Binding was evaluated by peptide-affinity chromatography and pull-down assays with PEDF-R-derived synthetic peptides or recombinant protein. Oxidative stress was induced in human ARPE-19 and primary pig RPE cells with indicated concentrations of H2O2/TNF-α. Reverse transcription-PCR of ALOX5 and PNPLA2 genes was performed. Cell viability and death rates were determined using respective biomarkers. Leukotriene B4 levels were measured by ELISA. RESULTS Among five peptides spanning between positions Leu159 and Met325 of human PEDF-R polypeptide, only two overlapping peptides, E5b and P1, bound and inhibited lipoxygenase activity. Human recombinant 5-LOX bound specifically to peptide P1 and to His6/Xpress-tagged PEDF-R via ionic interactions. The two inhibitor peptides E5b and P1 promoted cell viability and decreased cell death of RPE cells undergoing oxidative stress. Oxidative stress decreased the levels of PNPLA2 transcripts with no effect on ALOX5 expression. Exogenous additions of P1 peptide or overexpression of the PNPLA2 gene decreased both LTB4 levels and death of RPE cells undergoing oxidative stress. CONCLUSIONS A novel peptide region of PEDF-R inhibits 5-LOX, which intersects with RPE cell death pathways induced by oxidative stress.
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Affiliation(s)
- Preeti Subramanian
- Section of Protein Structure and Function-Laboratory of Retinal Cell and Molecular Biology National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Emily F Mendez
- Section of Protein Structure and Function-Laboratory of Retinal Cell and Molecular Biology National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - S Patricia Becerra
- Section of Protein Structure and Function-Laboratory of Retinal Cell and Molecular Biology National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
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Barajas‐Espinosa A, Ni NC, Yan D, Zarini S, Murphy RC, Funk CD. The cysteinyl leukotriene 2 receptor mediates retinal edema and pathological neovascularization in a murine model of oxygen‐induced retinopathy. FASEB J 2011; 26:1100-9. [DOI: 10.1096/fj.11-195792] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Alma Barajas‐Espinosa
- Department of Biomedical and Molecular SciencesQueen's UniversityKingstonOntarioCanada
| | - Nathan C. Ni
- Department of Biomedical and Molecular SciencesQueen's UniversityKingstonOntarioCanada
| | - Dong Yan
- Department of Biomedical and Molecular SciencesQueen's UniversityKingstonOntarioCanada
| | - Simona Zarini
- Department of PharmacologyUniversity of Colorado–DenverAuroraColoradoUSA
| | - Robert C. Murphy
- Department of PharmacologyUniversity of Colorado–DenverAuroraColoradoUSA
| | - Colin D. Funk
- Department of Biomedical and Molecular SciencesQueen's UniversityKingstonOntarioCanada
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Jackman SL, Babai N, Chambers JJ, Thoreson WB, Kramer RH. A positive feedback synapse from retinal horizontal cells to cone photoreceptors. PLoS Biol 2011; 9:e1001057. [PMID: 21559323 PMCID: PMC3086870 DOI: 10.1371/journal.pbio.1001057] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 03/25/2011] [Indexed: 12/31/2022] Open
Abstract
Cone photoreceptors and horizontal cells (HCs) have a reciprocal synapse that
underlies lateral inhibition and establishes the antagonistic center-surround
organization of the visual system. Cones transmit to HCs through an excitatory
synapse and HCs feed back to cones through an inhibitory synapse. Here we report
that HCs also transmit to cone terminals a positive feedback signal that
elevates intracellular Ca2+ and accelerates neurotransmitter
release. Positive and negative feedback are both initiated by AMPA receptors on
HCs, but positive feedback appears to be mediated by a change in HC
Ca2+, whereas negative feedback is mediated by a change in
HC membrane potential. Local uncaging of AMPA receptor agonists suggests that
positive feedback is spatially constrained to active HC-cone synapses, whereas
the negative feedback signal spreads through HCs to affect release from
surrounding cones. By locally offsetting the effects of negative feedback,
positive feedback may amplify photoreceptor synaptic release without sacrificing
HC-mediated contrast enhancement. Visual images are projected by the lens of the eye onto a sheet of photoreceptor
cells in the retina called rods and cones. Like the pixels in a digital camera,
each photoreceptor generates an electrical response proportional to the local
light intensity. Each photoreceptor then initiates a chemical signal that is
transmitted to downstream neurons, ultimately reaching the brain. But unlike the
pixels of a digital camera, photoreceptors indirectly inhibit one another
through laterally projecting horizontal cells. Horizontal cells integrate
signals from many photoreceptors and provide inhibitory feedback. This feedback
is thought to underlie “lateral inhibition,” a process that sharpens
our perception of contrast and color. Here we report the surprising finding that
horizontal cells also provide positive feedback to photoreceptors, utilizing a
mechanism distinct from negative feedback. The positive feedback signal is
constrained to individual horizontal cell–photoreceptor connections,
whereas the negative feedback signal spreads throughout a horizontal cell to
affect many surrounding photoreceptors. By locally offsetting negative feedback,
positive feedback boosts the photoreceptor signal while preserving contrast
enhancement.
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Affiliation(s)
- Skyler L. Jackman
- Department of Physics, University of California, Berkeley, Berkeley,
California, United States of America
| | - Norbert Babai
- Department of Ophthalmology, University of Nebraska Medical Center,
Omaha, Nebraska, United States of America
| | - James J. Chambers
- Department of Chemistry, University of Massachusetts, Amherst, Amherst,
Massachusetts, United States of America
| | - Wallace B. Thoreson
- Department of Ophthalmology, University of Nebraska Medical Center,
Omaha, Nebraska, United States of America
| | - Richard H. Kramer
- Department of Molecular and Cell Biology, University of California,
Berkeley, Berkeley, California, United States of America
- * E-mail:
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TRPV1 receptors modulate retinal development. Int J Dev Neurosci 2011; 29:405-13. [PMID: 21414401 DOI: 10.1016/j.ijdevneu.2011.03.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 01/19/2011] [Accepted: 03/08/2011] [Indexed: 12/11/2022] Open
Abstract
We investigated the possible participation of TRPV1 channels in retinal apoptosis and overall development. Retinas from newborn, male albino rats were treated in vitro with capsazepine, a TRPV1 antagonist. The expression of cell cycle markers was not changed after TRPV1 blockade, whereas capsazepine reduced the number of apoptotic cells throughout the retina,increased ERK1/2 and p38 phosphorylation and slightly reduced JNK phosphorylation. The expression of BAD, Bcl-2, as well as integral and cleaved capsase-3 were similar in all experimental conditions. Newborn rats were kept for 2 months after receiving high doses of capsazepine. In their retinas, calbindin and parvalbumin protein levels were upregulated, but only the number of amacrine-like, parvalbumin-positive cells was increased. The numbers of calretinin, calbindin, ChAT, vimentin, PKC-alpha and GABA-positive cells were similar in both conditions. Protein expression of synapsin Ib was also increased in the retinas of capsazepine-treated rats. Calretinin, vimentin, GFAP, synapsin Ia, synaptophysin and light neurofilament protein levels were not changed when compared to control values. Our results indicate that TRPV1 channels play a role in the control of the early apoptosis that occur during retinal development, which might be dependent on MAPK signaling. Moreover, it seems that TRPV1 function might be important for neuronal and synaptic maturation in the retina.
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Affiliation(s)
- Paulus T V M de Jong
- Department of Ophthalmogenetics, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands.
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8
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Suh M, Clandinin MT. 20:5n-3 but not 22:6n-3 is a preferred substrate for synthesis of n-3 very-long- chain fatty acids (C24-C36) in retina. Curr Eye Res 2006; 30:959-68. [PMID: 16282130 DOI: 10.1080/02713680500246957] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The objective of this study was to determine if 20:5n-3 or 22:6n-3 is the primary precursor of very-long-chain fatty acids (VLCFAs; C24-C36) synthesized in retina. Rats were fed semisynthetic, nutritionally complete diet containing 20% (w/w) fat with 3% (w/w) of 22:6n-3. After 6 weeks feeding, the vitreal fluid of each eye was injected with [3H]20:5n-3 or [3H]22:6n-3. Rats were then maintained under constant light (330 lux) or dark conditions for 48 hr. After 48 hr in vivo metabolism, the amount of label present in individual fatty acids was determined in major phospholipids in retina. For [3H]22:6n-3, 90% of total incorporation remained in 22:6n-3, whereas for [3H]20:5n-3 the label was actively incorporated into pentaenoic and hexaenoic VLCFAs up to 34 carbon chain length. 22:5n-3 derived from [3H]20:5n-3 was among the most highly labeled fatty acids. These observations suggest that 22:6n-3 is incorporated directly into retinal phospholipids without further metabolism, whereas 20:5n-3 and 22:5n-3 are metabolically active precursors for synthesis of VLCFAs.
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Affiliation(s)
- Miyoung Suh
- Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
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Wenzel A, Grimm C, Samardzija M, Remé CE. Molecular mechanisms of light-induced photoreceptor apoptosis and neuroprotection for retinal degeneration. Prog Retin Eye Res 2004; 24:275-306. [PMID: 15610977 DOI: 10.1016/j.preteyeres.2004.08.002] [Citation(s) in RCA: 445] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Human retinal dystrophies and degenerations and light-induced retinal degenerations in animal models are sharing an important feature: visual cell death by apoptosis. Studying apoptosis may thus provide an important handle to understand mechanisms of cell death and to develop potential rescue strategies for blinding retinal diseases. Apoptosis is the regulated elimination of individual cells and constitutes an almost universal principle in developmental histogenesis and organogenesis and in the maintenance of tissue homeostasis in mature organs. Here we present an overview on molecular and cellular mechanisms of apoptosis and summarize recent developments. The classical concept of apoptosis being initiated and executed by endopeptidases that cleave proteins at aspartate residues (Caspases) can no longer be held in its strict sense. There is an increasing number of caspase-independent pathways, involving apoptosis inducing factor, endonuclease G, poly-(ADP-ribose) polymerase-1, proteasomes, lysosomes and others. Similarly, a considerable number and diversity of pro-apoptotic stimuli is being explored. We focus on apoptosis pathways in our model: light-damage induced by short exposures to bright white light and highlight those essential conditions known so far in the apoptotic death cascade. In our model, the visual pigment rhodopsin is the essential mediator of the initial death signal. The rate of rhodopsin regeneration defines damage threshold in different strains of mice. This rate depends on the level of the pigment epithelial protein RPE65, which in turn depends on the amino acid (leucine or methionine) encoded at position 450. Activation of the pro-apoptotic transcription factor AP-1 constitutes an essential death signal. Inhibition of rhodopsin regeneration as well as suppression of AP-1 confers complete protection in our system. Furthermore, we describe observations in other light-damage systems as well as characteristics of animal models for RP with particular emphasis on rescue strategies. There is a vast array of different neuroprotective cytokines that are applied in light-damage and RP animal models and show diverging efficacy. Some cytokines protect against light damage as well as against RP in animal models. At present, the mechanisms of neuroprotective/anti-apoptotic action represent a "black box" which needs to be explored. Even though acute light damage and RP animal models show different characteristics in many respects, we hope to gain insights into apoptotic mechanisms for both conditions by studying light damage and comparing results with those obtained in animal models. In our view, future directions may include the investigation of different apoptotic pathways in light damage (and inherited animal models). Emphasis should also be placed on mechanisms of removal of dead cells in apoptosis, which appears to be more important than initially recognized. In this context, a stimulating concept concerns age-related macular degeneration, where an insufficiency of macrophages removing debris that results from cell death and photoreceptor turnover might be an important pathogenetic event. In acute light damage, the appearance of macrophages as well as phagocytosis by the retinal pigment epithelium are a consistent and conspicuous feature, which lends itself to the study of removal of cellular debris in apoptosis. We are aware of the many excellent reviews and the earlier work paving the way to our current knowledge and understanding of retinal degeneration, photoreceptor apoptosis and neuroprotection. However, we limited this review mainly to work published in the last 7-8 years and we apologize to all the researchers which have contributed to the field but are not cited here.
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Affiliation(s)
- Andreas Wenzel
- Laboratory for Retinal Cell Biology, Department Ophthalmology, University Eye Clinic, University of Zurich, Frauenklinkstrasse 24, CH-8091 Zurich, Switzerland
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10
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Abstract
Crystalline deposits in the retina may be associated with a wide variety of systemic disorders such as oxalosis, cystinosis, hyperornithinaemia and Sjögren-Larsson syndrome. Refractile crystalline deposits may also be a manifestation of drug toxicity like the antineoplastic agent tamoxifen, the anesthetic methoxyflurane and the oral tanning agent canthaxanthine. Crystals may also occur in drug abusers who inject multiple crushed tablets of methadone or meperidine intravenously (talc retinopathy). The differential diagnosis of retinal crystals also includes primary ocular diseases like Bietti's crystalline retinopathy, calcified macular drusen, idiopathic parafoveal telangiectasis and longstanding retinal detachment. This article will review the most common causes of crystalline retinopathies, their etiologies, pathologies and clinical characteristics.
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Affiliation(s)
- F Nadim
- Department of Ophthalmology, American University of Beirut, Lebanon.
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Willemsen MA, Cruysberg JR, Rotteveel JJ, Aandekerk AL, Van Domburg PH, Deutman AF. Juvenile macular dystrophy associated with deficient activity of fatty aldehyde dehydrogenase in Sjögren-Larsson syndrome. Am J Ophthalmol 2000; 130:782-9. [PMID: 11124298 DOI: 10.1016/s0002-9394(00)00576-6] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PURPOSE To report the ocular manifestations associated with the Sjögren-Larsson syndrome in a series of patients with proven fatty aldehyde dehydrogenase deficiency. To emphasize the clinical importance of the ophthalmological features of the Sjögren-Larsson syndrome. To discuss the metabolic disturbances that might give rise to the ophthalmological picture. METHODS Fifteen patients with Sjögren-Larsson syndrome underwent a standardized ophthalmological examination. In patients of appropriate age, and who were able to cooperate, additional investigations were performed. RESULTS All patients exhibited bilateral, glistening yellow-white crystalline deposits that were located in the innermost retinal layers and appeared during the first 2 years of life. Repeated fundus photography in individual patients showed that the dots became more numerous as the patients got older. Photophobia, subnormal visual acuity, myopia, and astigmatism were found in most of the patients. Fluorescein angiography was performed in three patients and showed a mottled hyperfluorescence of the retinal pigment epithelium, without leakage. Color vision, electroretinography, and electro-oculography could be performed in only a small number of patients and showed no abnormalities. Visual evoked potentials were found to be abnormal in six of eight patients. CONCLUSIONS In Sjögren-Larsson syndrome, patients exhibit highly characteristic bilateral, glistening yellow-white retinal dots from the age of 1 to 2 years onward. The number of dots increases with age. The extent of the macular abnormality does not correlate with the severity of the ichthyosis or with the severity of the neurological abnormalities. A high percentage of patients shows additional ocular signs and symptoms, notably marked photophobia.
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Affiliation(s)
- M A Willemsen
- Department of Pediatric Neurology, University Hospital Nijmegen, Nijmegan, The Netherlands.
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12
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Sastry BV, Hemontolor ME. Influence of nicotine and cotinine on retinal phospholipase A2 and its significance to macular function. J Ocul Pharmacol Ther 1998; 14:447-58. [PMID: 9811234 DOI: 10.1089/jop.1998.14.447] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The macula is a constituent of the sensory retina that is necessary for sharp contrast and color vision. A significant relationship has been found between tobacco smoking and age-related macular degeneration. Opsin, rhodopsin and phospholipase A2 (PLA2) are located in excitable membranes of retina which are enriched with polyunsaturated fatty acids (PUFA). A question may arise as to whether nicotine and its major metabolite cotinine influence PLA2 so that arachidonic acid (AA) and proinflammatory prostaglandins (PG) are produced in the retina. Therefore, the effects of nicotine and cotinine on the retinal PLA2 were studied. PLA2 activity of rat retinal sonicates was assayed using 1-palmitoyl-2[1-14C]arachidonyl-Phosphatidylethanolamine (PE, 2.2 nmol) as a substrate in Tris buffer (10 mM, pH 7.4) at 37 degrees C with and without nicotine or cotinine in the assay medium. These studies gave the following results: (1) Rat retinal PLA2 activity was 4.2+/-0.8 pmol PE hydrolyzed/100 ng protein/hr. (2) Nicotine in low concentrations (1-150 nM) activated PLA2 (EC50 5 nM). (3) Cotinine also activated PLA2 (EC50 300 nM). (4) Only high concentrations of nicotine (> 1.0 microM) and cotinine (> 25 microM) exhibit inhibition of PLA2. (5) All three known PLA2 inhibitors, mepacrine, 4-bromophenacyl bromide and bromoacetylcholine bromide (IC50: 0.5mM, 88 microM, 30 mM, respectively) inhibited retinal PLA2 activity. These observations suggest that polyunsaturated fatty acids are cleaved, and arachidonic acid, the precursor for prostaglandins and related pro-inflammatory mediators, is liberated by nicotine and cotinine. Oxidative stress (reduced levels of antioxidants), vascular insufficiency, as well as activation of PLA2 by nicotine and cotinine may contribute for retinal degeneration in smokers during aging.
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Affiliation(s)
- B V Sastry
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-4125, USA
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13
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Abstract
Apoptosis is a regulated mode of single cell death that involves gene expression in many instances and occurs under physiological and pathological conditions in a large variety of systems. We briefly summarize major features of apoptosis in general and describe the occurrence of apoptosis in the retina in different situations that comprise animal models of retinitis pigmentosa, light-induced lesions, histogenesis during development, and others. Apoptosis can be separated into several phases: the induction by a multitude of stimuli, the effector phase in which the apoptotic signal is transmitted to the cellular death machinery, the excecution period when proteolytic cascades are activated, and the phagocytic removal of cellular remnants. Control mechanisms for retinal apoptosis are only beginning to be clarified. Potential apoptotic signal transducers were investigated in our laboratory, including metabolites of arachidonic acid and downstream mediators of signaling molecules such as transcription factors. Work in our laboratory revealed an essential role of the immediate-early gene product c-Fos in light-induced apoptosis. c-Fos is a member of the AP-1 family of transcription factors and, together with other members of this family, it may regulate apoptosis in the central nervous system. Expression of the c-fos gene in the retina can be evoked by light exposure and follows a diurnal rhythm. Future studies will have to clarify how light can control the expression of specific genes, and specifically, the role of c-fos and other genes of retinal apoptosis including potential target genes and signaling pathways.
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Affiliation(s)
- C E Remé
- Department of Ophthalmology, University Hospital, Zuerich, Switzerland.
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14
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Hafezi F, Marti A, Munz K, Remé CE. Light-induced apoptosis: differential timing in the retina and pigment epithelium. Exp Eye Res 1997; 64:963-70. [PMID: 9301477 DOI: 10.1006/exer.1997.0288] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Apoptosis is a genetically regulated form of cell death. Individual cells show condensed nuclear chromatin and cytoplasm, and biochemical analysis reveals fragmentation of the DNA. Ensuing cellular components, apoptotic bodies, are removed by macrophages or neighboring cells. Genes involved in the regulation of apoptosis as well as stimuli and signal transduction systems, are only beginning to be understood in the retina. Therefore, we developed a new in vivo model system for the investigation of events leading to apoptosis in the retina and the pigment epithelium. We induced apoptosis in retinal photoreceptors and the pigment epithelium of albino rats by exposure to 3000 lux of diffuse, cool white fluorescent light for short time periods of up to 120 minutes. Animals were killed at different time intervals during and after light exposure. The eyes were enucleated and the lower central retina was processed for light- and electron microscopy. DNA fragmentation was analysed in situ by TdT-mediated dUTP nick-end labeling (TUNEL) or by gel electrophoresis of total retinal DNA. We observed that the timing of apoptosis in the photoreceptors and pigment epithelium was remarkably different, the pigment epithelium showing a distinct delay of several hours before the onset of apoptosis. In photoreceptors, apoptosis was induced within 90 minutes of light exposure, with the morphological appearance of apoptosis preceding the fragmentation of DNA. In the pigment epithelium, the morphological appearance of apoptosis and DNA fragmentation were coincident. Different regulative mechanisms may lead to apoptotic cell death in the retinal photoreceptors and pigment epithelium. This in vivo model system will allow measurement of dose-responses, a potential spectral dependence and the molecular background of apoptotic mechanisms in the retina.
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Affiliation(s)
- F Hafezi
- Department of Ophthalmology, University Hospital, Zurich, Switzerland
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Hafezi F, Steinbach JP, Marti A, Munz K, Wang ZQ, Wagner EF, Aguzzi A, Remé CE. The absence of c-fos prevents light-induced apoptotic cell death of photoreceptors in retinal degeneration in vivo. Nat Med 1997; 3:346-9. [PMID: 9055866 DOI: 10.1038/nm0397-346] [Citation(s) in RCA: 194] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Apoptotic cell death in the retina was recently demonstrated in animal models of the hereditary human retinal dystrophy known as retinitis pigmentosa. Although recent evidence indicates that the proto-oncogene c-fos is a mediator of apoptosis, its precise role is unclear. In fact, under some conditions, c-fos may even protect against apoptotic cell death. In the retina, c-fos is physiologically expressed in a diurnal manner and is inducible by light. We previously observed a light-elicited, dose-dependent apoptotic response in rat photoreceptors. To determine whether c-fos is involved in the light-induced apoptotic pathway we have used control mice and mice lacking c-fos. We found that following dark adaptation and two hours of light exposure both groups of animals exhibited only a few apoptotic cells. However, at 12 and 24 additional hours after light exposure, apoptosis increased dramatically in controls but was virtually absent in those mice lacking c-fos. Therefore, c-fos is essential for light-induced apoptosis of photoreceptors. Notably, c-fos is continuously upregulated concomitant with apoptotic photoreceptor death in our system and in animal models of retinitis pigmentosa (Agarwal, N. et al., Invest. Ophthalmol. Vis.Sci. Suppl. 36, S638 and Rich, K.A. et al., Invest. Ophthalmol. Vis. Sci. Suppl. 35, 1833). Inhibition of c-fos expression might therefore represent a novel therapeutic strategy to retard the time course of retinal dystrophies and light-induced retinal degeneration.
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Affiliation(s)
- F Hafezi
- Department of Ophthalmology, University Clinic, Zurich, Switzerland
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