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Curcio CA, Zanzottera EC, Ach T, Balaratnasingam C, Freund KB. Activated Retinal Pigment Epithelium, an Optical Coherence Tomography Biomarker for Progression in Age-Related Macular Degeneration. Invest Ophthalmol Vis Sci 2017; 58:BIO211-BIO226. [PMID: 28785769 PMCID: PMC5557213 DOI: 10.1167/iovs.17-21872] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Purpose To summarize and contextualize recent histology and clinical imaging publications on retinal pigment epithelium (RPE) fate in advanced age-related macular degeneration (AMD); to support RPE activation and migration as important precursors to atrophy, manifest as intraretinal hyperreflective foci in spectral-domain optical coherence tomography (SDOCT). Methods The Project MACULA online resource for AMD histopathology was surveyed systematically to form a catalog of 15 phenotypes of RPE and RPE-derived cells and layer thicknesses in advanced disease. Phenotypes were also sought in correlations with clinical longitudinal eye-tracked SDOCT and with ex vivo imaging–histopathology correlations in geographic atrophy (GA) and pigment epithelium detachments (PED). Results The morphology catalog suggested two main pathways of RPE fate: basolateral shedding of intracellular organelles (apparent apoptosis in situ) and activation with anterior migration. Acquired vitelliform lesions may represent a third pathway. Migrated cells are packed with RPE organelles and confirmed as hyperreflective on SDOCT. RPE layer thickening due to cellular dysmorphia and thick basal laminar deposit is observed near the border of GA. Drusenoid PED show a life cycle of slow growth and rapid collapse preceded by RPE layer disruption and anterior migration. Conclusions RPE activation and migration comprise an important precursor to atrophy that can be observed at the cellular level in vivo via validated SDOCT. Collapse of large drusen and drusenoid PED appears to occur when RPE death and migration prevent continued production of druse components. Data implicate excessive diffusion distance from choriocapillaris in RPE death as well as support a potential benefit in targeting drusen in GA.
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Affiliation(s)
- Christine A Curcio
- Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, Alabama, United States
| | - Emma C Zanzottera
- Eye Clinic, Department of Clinical Science "Luigi Sacco," Sacco Hospital, University of Milan, Milan, Italy
| | - Thomas Ach
- University Hospital Würzburg, Department of Ophthalmology, Würzburg, Germany
| | - Chandrakumar Balaratnasingam
- Center for Ophthalmology and Visual Sciences, Lions Eye Institute, University of Western Australia, Perth, Australia.,Sir Charles Gairdner Hospital, Perth, Australia
| | - K Bailey Freund
- Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, Alabama, United States.,Eye Clinic, Department of Clinical Science "Luigi Sacco," Sacco Hospital, University of Milan, Milan, Italy.,University Hospital Würzburg, Department of Ophthalmology, Würzburg, Germany.,Center for Ophthalmology and Visual Sciences, Lions Eye Institute, University of Western Australia, Perth, Australia.,Sir Charles Gairdner Hospital, Perth, Australia.,Vitreous Retina Macula Consultants of New York, New York, New York, United States.,LuEsther T. Mertz Retinal Research Center, Manhattan Eye, Ear, and Throat Institute, New York, New York, United States.,Department of Ophthalmology, New York University Langone School of Medicine, New York, New York, United States
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102
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Yang P, Skiba NP, Tewkesbury GM, Treboschi VM, Baciu P, Jaffe GJ. Complement-Mediated Regulation of Apolipoprotein E in Cultured Human RPE Cells. Invest Ophthalmol Vis Sci 2017. [PMID: 28632844 PMCID: PMC5482245 DOI: 10.1167/iovs.16-20083] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Purpose. Complement activation is implicated in the pathogenesis of age-related macular degeneration (AMD). Apolipoprotein E (ApoE) and complement activation products such as membrane attack complex (MAC) are present in eyes of individuals with AMD. Herein, we investigated the effect of complement activation on induction of ApoE accumulation in human retinal pigment epithelial (RPE) cells. Methods. Cultured human RPE cells were primed with a complement-fixing antibody followed by treatment with C1q-depleted (C1q-Dep) human serum to elicit alternative pathway complement activation. Controls included anti-C5 antibody-treated serum and heat-inactivated C1q-Dep. Total protein was determined on RPE cell extracts, conditioned media, and extracellular matrix (ECM) by Western blot. ApoE and MAC colocalization was assessed on cultured RPE cells and human eyes by immunofluorescent stain. ApoE mRNA expression was evaluated by quantitative PCR (qPCR). Results. Complement challenge upregulated cell-associated ApoE, but not apolipoprotein A1. ApoE accumulation was blocked by anti-C5 antibody and enhanced by repetitive complement challenge. ApoE mRNA levels were not affected by complement challenge. ApoE was frequently colocalized with MAC in complement-treated cells and drusen from human eyes. ApoE was released into complement-treated conditioned media after a single complement challenge and accumulated on ECM after repetitive complement challenge. Conclusions. Complement challenge induces time-dependent ApoE accumulation in RPE cells. An understanding of the mechanisms by which complement affects RPE ApoE accumulation may help to better explain drusen composition, and provide insights into potential therapeutic targets.
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Affiliation(s)
- Ping Yang
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, United States
| | - Nikolai P Skiba
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, United States
| | - Grace M Tewkesbury
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, United States
| | - Victoria M Treboschi
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, United States
| | - Peter Baciu
- Department of Biology, Allergan, Inc., Irvine, California, United States
| | - Glenn J Jaffe
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, United States
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103
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Zayas-Santiago A, Cross SD, Stanton JB, Marmorstein AD, Marmorstein LY. Mutant Fibulin-3 Causes Proteoglycan Accumulation and Impaired Diffusion Across Bruch's Membrane. Invest Ophthalmol Vis Sci 2017. [PMID: 28622396 PMCID: PMC5477800 DOI: 10.1167/iovs.17-21720] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Purpose The mutation R345W in EFEMP1 (fibulin-3) causes macular degeneration. This study sought to determine whether proteoglycan content and diffusion across Bruch's membrane are altered in Efemp1ki/ki mice carrying this mutation or in Efemp1−/− mice. Methods Proteoglycans in mouse Bruch's membranes were stained with Cupromeronic Blue (CB). Heparan sulfated proteoglycan (HSPG) and chondroitin/dermatan sulfate proteoglycan (C/DSPG) distributions were visualized following treatments with chondroitinase ABC (C-ABC) or nitrous acid. Total sulfated glycosaminoglycans (sGAGs) in Bruch's membrane/choroid (BrM/Ch) were measured with dimethylmethylene blue (DMMB). Matrix metalloprotease (MMP)-2, MMP-9, and tissue inhibitor of metalloproteinase (TIMP)-3 were examined by immunofluorescence and quantified using Image J. Molecules with different Stokes radius (Rs) were allowed simultaneously to diffuse through mouse BrM/Ch mounted in a modified Ussing chamber. Samples were quantified using gel exclusion chromatography. Results HSPGs and C/DSPGs were markedly increased in Efemp1ki/ki Bruch's membrane, and MMP-2 and MMP-9 were decreased, but TIMP-3 was increased. Diffusion across Efemp1ki/ki Bruch's membrane was impaired. In contrast, the proteoglycan amount in Efemp1−/− Bruch's membrane was not significantly different, but the size of proteoglycans was much larger. MMP-2, MMP-3, and TIMP-3 levels were similar to that of Efemp1+/+ mice, but they were localized diffusely in retinal pigment epithelium (RPE) cells instead of Bruch's membrane. Diffusion across Efemp1−/− Bruch's membrane was enhanced. Conclusions Mutant fibulin-3 causes proteoglycan accumulation, reduction of MMP-2 and MMP-9, but increase of TIMP-3, and impairs diffusion across Bruch's membrane. Fibulin-3 ablation results in altered sizes of proteoglycans, altered distributions of MMP-2, MMP-9, and TIMP-3, and enhances diffusion across Bruch's membrane.
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Affiliation(s)
- Astrid Zayas-Santiago
- Department of Pathology & Laboratory Medicine, Universidad Central del Caribe, Bayamón, Puerto Rico
| | - Samuel D Cross
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - James B Stanton
- Department of Ophthalmology & Vision Science, University of Arizona, Tucson, Arizona, United States
| | - Alan D Marmorstein
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - Lihua Y Marmorstein
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
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104
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Pilgrim MG, Lengyel I, Lanzirotti A, Newville M, Fearn S, Emri E, Knowles JC, Messinger JD, Read RW, Guidry C, Curcio CA. Subretinal Pigment Epithelial Deposition of Drusen Components Including Hydroxyapatite in a Primary Cell Culture Model. Invest Ophthalmol Vis Sci 2017; 58:708-719. [PMID: 28146236 PMCID: PMC5295770 DOI: 10.1167/iovs.16-21060] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Purpose Extracellular deposits containing hydroxyapatite, lipids, proteins, and trace metals that form between the basal lamina of the RPE and the inner collagenous layer of Bruch's membrane are hallmarks of early AMD. We examined whether cultured RPE cells could produce extracellular deposits containing all of these molecular components. Methods Retinal pigment epithelium cells isolated from freshly enucleated porcine eyes were cultured on Transwell membranes for up to 6 months. Deposit composition and structure were characterized using light, fluorescence, and electron microscopy; synchrotron x-ray diffraction and x-ray fluorescence; secondary ion mass spectroscopy; and immunohistochemistry. Results Apparently functional primary RPE cells, when cultured on 10-μm-thick inserts with 0.4-μm-diameter pores, can produce sub-RPE deposits that contain hydroxyapatite, lipids, proteins, and trace elements, without outer segment supplementation, by 12 weeks. Conclusions The data suggest that sub-RPE deposit formation is initiated, and probably regulated, by the RPE, as well as the loss of permeability of the Bruch's membrane and choriocapillaris complex associated with age and early AMD. This cell culture model of early AMD lesions provides a novel system for testing new therapeutic interventions against sub-RPE deposit formation, an event occurring well in advance of the onset of vision loss.
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Affiliation(s)
- Matthew G Pilgrim
- UCL Institute of Ophthalmology, University College London, London, United Kingdom 2Division of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, University College London, London, United Kingdom
| | - Imre Lengyel
- UCL Institute of Ophthalmology, University College London, London, United Kingdom 3Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom
| | - Antonio Lanzirotti
- Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois, United States
| | - Matt Newville
- Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois, United States
| | - Sarah Fearn
- Department of Materials, Imperial College London, London, United Kingdom
| | - Eszter Emri
- UCL Institute of Ophthalmology, University College London, London, United Kingdom 3Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom
| | - Jonathan C Knowles
- Division of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, University College London, London, United Kingdom
| | - Jeffrey D Messinger
- Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, Alabama, United States
| | - Russell W Read
- Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, Alabama, United States
| | - Clyde Guidry
- Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, Alabama, United States
| | - Christine A Curcio
- Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, Alabama, United States
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105
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Ex-vivo models of the Retinal Pigment Epithelium (RPE) in long-term culture faithfully recapitulate key structural and physiological features of native RPE. Tissue Cell 2017; 49:447-460. [PMID: 28669519 PMCID: PMC5545183 DOI: 10.1016/j.tice.2017.06.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 06/16/2017] [Accepted: 06/16/2017] [Indexed: 01/06/2023]
Abstract
Damage to the Retinal Pigment Epithelium (RPE) is a key feature of retinopathy. We describe 2 substrates which support RPE cultures for long-term studies. Substrates were; a polyester transwell membrane and a novel electrospun scaffold. Both support RPE cultures with structural and functional features of native RPE. Electrospun scaffolds may be better for studying some disease-linked RPE changes.
The Retinal Pigment Epithelium (RPE) forms the primary site of pathology in several blinding retinopathies. RPE cultures are being continuously refined so that dynamic disease processes in this important monolayer can be faithfully studied outside the eye over longer periods. The RPE substrate, which mimics the supportive Bruch’s membrane (BrM), plays a key role in determining how well in-vitro cultures recapitulate native RPE cells. Here, we evaluate how two different types of BrM substrates; (1) a commercially-available polyester transwell membrane, and (2) a novel electrospun scaffold developed in our laboratory, could support the generation of realistic RPE tissues in culture. Our findings reveal that both substrates were capable of supporting long-lasting RPE monolayers with structural and functional specialisations of in-situ RPE cells. These cultures were used to study autofluorescence and barrier formation, as well as activities such as outer-segment internalisation/trafficking and directional secretion of key proteins; the impairment of which underlies retinal disease. Hence, both substrates fulfilled important criteria for generating authentic in-vitro cultures and act as powerful tools to study RPE pathophysiology. However, RPE grown on electrospun scaffolds may be better suited to studying complex RPE-BrM interactions such as the formation of drusen-like deposits associated with early retinal disease.
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106
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Chao JR, Knight K, Engel AL, Jankowski C, Wang Y, Manson MA, Gu H, Djukovic D, Raftery D, Hurley JB, Du J. Human retinal pigment epithelial cells prefer proline as a nutrient and transport metabolic intermediates to the retinal side. J Biol Chem 2017; 292:12895-12905. [PMID: 28615447 DOI: 10.1074/jbc.m117.788422] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/30/2017] [Indexed: 11/06/2022] Open
Abstract
Metabolite transport is a major function of the retinal pigment epithelium (RPE) to support the neural retina. RPE dysfunction plays a significant role in retinal degenerative diseases. We have used mass spectrometry with 13C tracers to systematically study nutrient consumption and metabolite transport in cultured human fetal RPE. LC/MS-MS detected 120 metabolites in the medium from either the apical or basal side. Surprisingly, more proline is consumed than any other nutrient, including glucose, taurine, lipids, vitamins, or other amino acids. Besides being oxidized through the Krebs cycle, proline is used to make citrate via reductive carboxylation. Citrate, made either from 13C proline or from 13C glucose, is preferentially exported to the apical side and is taken up by the retina. In conclusion, RPE cells consume multiple nutrients, including glucose and taurine, but prefer proline, and they actively synthesize and export metabolic intermediates to the apical side to nourish the outer retina.
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Affiliation(s)
- Jennifer R Chao
- Department of Ophthalmology, University of Washington, Seattle, Washington 98109.
| | - Kaitlen Knight
- Department of Ophthalmology, University of Washington, Seattle, Washington 98109
| | - Abbi L Engel
- Department of Ophthalmology, University of Washington, Seattle, Washington 98109
| | - Connor Jankowski
- Department of Biochemistry, University of Washington, Seattle, Washington 98109
| | - Yekai Wang
- Department of Ophthalmology, West Virginia University, Morgantown, West Virginia 26506; Department of Biochemistry, West Virginia University, Morgantown, West Virginia 26506
| | - Megan A Manson
- Department of Ophthalmology, University of Washington, Seattle, Washington 98109
| | - Haiwei Gu
- Northwest Metabolomics Research Center, Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, Washington 98109
| | - Danijel Djukovic
- Northwest Metabolomics Research Center, Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, Washington 98109
| | - Daniel Raftery
- Northwest Metabolomics Research Center, Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, Washington 98109
| | - James B Hurley
- Department of Ophthalmology, University of Washington, Seattle, Washington 98109; Department of Biochemistry, University of Washington, Seattle, Washington 98109
| | - Jianhai Du
- Department of Ophthalmology, West Virginia University, Morgantown, West Virginia 26506; Department of Biochemistry, West Virginia University, Morgantown, West Virginia 26506.
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107
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Saini JS, Corneo B, Miller JD, Kiehl TR, Wang Q, Boles NC, Blenkinsop TA, Stern JH, Temple S. Nicotinamide Ameliorates Disease Phenotypes in a Human iPSC Model of Age-Related Macular Degeneration. Cell Stem Cell 2017; 20:635-647.e7. [PMID: 28132833 DOI: 10.1016/j.stem.2016.12.015] [Citation(s) in RCA: 119] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 10/14/2016] [Accepted: 12/30/2016] [Indexed: 12/22/2022]
Abstract
Age-related macular degeneration (AMD) affects the retinal pigment epithelium (RPE), a cell monolayer essential for photoreceptor survival, and is the leading cause of vision loss in the elderly. There are no disease-altering therapies for dry AMD, which is characterized by accumulation of subretinal drusen deposits and complement-driven inflammation. We report the derivation of human-induced pluripotent stem cells (hiPSCs) from patients with diagnosed AMD, including two donors with the rare ARMS2/HTRA1 homozygous genotype. The hiPSC-derived RPE cells produce several AMD/drusen-related proteins, and those from the AMD donors show significantly increased complement and inflammatory factors, which are most exaggerated in the ARMS2/HTRA1 lines. Using a panel of AMD biomarkers and candidate drug screening, combined with transcriptome analysis, we discover that nicotinamide (NAM) ameliorated disease-related phenotypes by inhibiting drusen proteins and inflammatory and complement factors while upregulating nucleosome, ribosome, and chromatin-modifying genes. Thus, targeting NAM-regulated pathways is a promising avenue for developing therapeutics to combat AMD.
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Affiliation(s)
- Janmeet S Saini
- Neural Stem Cell Institute, Rensselaer, NY 12144, USA; Department of Biomedical Sciences, University at Albany - SUNY, Albany, NY 12201, USA
| | - Barbara Corneo
- Stem Cell Core Facility, Columbia University Medical Center, New York, NY 10032, USA
| | | | | | - Qingjie Wang
- Neural Stem Cell Institute, Rensselaer, NY 12144, USA
| | | | - Timothy A Blenkinsop
- Black Family Stem Cell Institute, Mount Sinai School of Medicine, New York, NY 10029, USA
| | | | - Sally Temple
- Neural Stem Cell Institute, Rensselaer, NY 12144, USA.
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108
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Golestaneh N, Chu Y, Xiao YY, Stoleru GL, Theos AC. Dysfunctional autophagy in RPE, a contributing factor in age-related macular degeneration. Cell Death Dis 2017; 8:e2537. [PMID: 28055007 PMCID: PMC5386365 DOI: 10.1038/cddis.2016.453] [Citation(s) in RCA: 236] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 12/05/2016] [Accepted: 12/07/2016] [Indexed: 12/17/2022]
Abstract
Age-related macular degeneration (AMD) is a devastating neurodegenerative disease and a major cause of blindness in the developed world. Owing to its complexity and the lack of an adequate human model that recapitulates key aspects of the disease, the molecular mechanisms of AMD pathogenesis remain poorly understood. Here we show that cultured human retinal pigment epithelium (RPE) from AMD donors (AMD RPE) are functionally impaired and exhibit distinct phenotypes compared with RPE cultured from normal donors (normal RPE). Accumulation of lipid droplets and glycogen granules, disintegration of mitochondria, and an increase in autophagosomes were observed in AMD RPE cultures. Compared with normal RPE, AMD RPE exhibit increased susceptibility to oxidative stress, produce higher levels of reactive oxygen species (ROS) under stress conditions, and showed reduced mitochondrial activity. Measurement of the ratio of LC3-II/ LC3-I, revealed impaired autophagy in AMD RPE as compared with normal RPE. Autophagic flux was also reduced in AMD RPE as compared with normal RPE, as shown by inability of AMD RPE to downregulate p62 levels during starvation. Impaired autophagic pathways were further shown by analyzing late autophagic vesicles; immunostaining with lysosome-associated membrane protein 1 (LAMP-1) antibody revealed enlarged and annular LAMP-1-positive organelles in AMD RPE as opposed to smaller discrete puncta observed in normal RPE. Our study provides insights into AMD cellular and molecular mechanisms, proposes dysfunctional autophagy as an underlying mechanism contributing to the pathophysiology of the disease, and opens up new avenues for development of novel treatment strategies.
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Affiliation(s)
- Nady Golestaneh
- Department of Ophthalmology, Georgetown University Medical Center, Washington, DC, USA
- Department of Neurology, Georgetown University Medical Center, Washington, DC, USA
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center, Washington, DC, USA
| | - Yi Chu
- Department of Ophthalmology, Georgetown University Medical Center, Washington, DC, USA
| | - Yang-Yu Xiao
- Department of Ophthalmology, Georgetown University Medical Center, Washington, DC, USA
| | - Gianna L Stoleru
- Department of Ophthalmology, Georgetown University Medical Center, Washington, DC, USA
| | - Alexander C Theos
- Department of Human Science, Georgetown University, Washington, DC, USA
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109
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Mohan RR, Cabrera AP, Harrison RES, Gorham RD, Johnson LV, Ghosh K, Morikis D. Peptide redesign for inhibition of the complement system: Targeting age-related macular degeneration. Mol Vis 2016; 22:1280-1290. [PMID: 27829783 PMCID: PMC5082644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Accepted: 10/24/2016] [Indexed: 11/30/2022] Open
Abstract
PURPOSE To redesign a complement-inhibiting peptide with the potential to become a therapeutic for dry and wet age-related macular degeneration (AMD). METHODS We present a new potent peptide (Peptide 2) of the compstatin family. The peptide is developed by rational design, based on a mechanistic binding hypothesis, and structural and physicochemical properties derived from molecular dynamics (MD) simulation. The inhibitory activity, efficacy, and solubility of Peptide 2 are evaluated using a hemolytic assay, a human RPE cell-based assay, and ultraviolet (UV) absorption properties, respectively, and compared to the respective properties of its parent peptide (Peptide 1). RESULTS The sequence of Peptide 2 contains an arginine-serine N-terminal extension (a characteristic of parent Peptide 1) and a novel 8-polyethylene glycol (PEG) block C-terminal extension. Peptide 2 has significantly improved aqueous solubility compared to Peptide 1 and comparable complement inhibitory activity. In addition, Peptide 2 is more efficacious in inhibiting complement activation in a cell-based model that mimics the pathobiology of dry AMD. CONCLUSIONS We have designed a new peptide analog of compstatin that combines N-terminal polar amino acid extensions and C-terminal PEGylation extensions. This peptide demonstrates significantly improved aqueous solubility and complement inhibitory efficacy, compared to the parent peptide. The new peptide overcomes the aggregation limitation for clinical translation of previous compstatin analogs and is a candidate to become a therapeutic for the treatment of AMD.
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Affiliation(s)
- Rohith R. Mohan
- Department of Bioengineering, University of California, Riverside, CA
| | - Andrea P. Cabrera
- Department of Bioengineering, University of California, Riverside, CA
| | | | - Ronald D. Gorham
- Department of Bioengineering, University of California, Riverside, CA
| | - Lincoln V. Johnson
- Center for the Study of Macular Degeneration, Neuroscience Research Institute, University of California, Santa Barbara, CA
| | - Kaustabh Ghosh
- Department of Bioengineering, University of California, Riverside, CA
| | - Dimitrios Morikis
- Department of Bioengineering, University of California, Riverside, CA
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110
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Pluripotent Stem Cell-Based Therapies in Combination with Substrate for the Treatment of Age-Related Macular Degeneration. J Ocul Pharmacol Ther 2016; 32:261-71. [DOI: 10.1089/jop.2015.0153] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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111
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Kauppinen A, Paterno JJ, Blasiak J, Salminen A, Kaarniranta K. Inflammation and its role in age-related macular degeneration. Cell Mol Life Sci 2016; 73:1765-86. [PMID: 26852158 PMCID: PMC4819943 DOI: 10.1007/s00018-016-2147-8] [Citation(s) in RCA: 450] [Impact Index Per Article: 56.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 01/21/2016] [Accepted: 01/25/2016] [Indexed: 01/05/2023]
Abstract
Inflammation is a cellular response to factors that challenge the homeostasis of cells and tissues. Cell-associated and soluble pattern-recognition receptors, e.g. Toll-like receptors, inflammasome receptors, and complement components initiate complex cellular cascades by recognizing or sensing different pathogen and damage-associated molecular patterns, respectively. Cytokines and chemokines represent alarm messages for leukocytes and once activated, these cells travel long distances to targeted inflamed tissues. Although it is a crucial survival mechanism, prolonged inflammation is detrimental and participates in numerous chronic age-related diseases. This article will review the onset of inflammation and link its functions to the pathogenesis of age-related macular degeneration (AMD), which is the leading cause of severe vision loss in aged individuals in the developed countries. In this progressive disease, degeneration of the retinal pigment epithelium (RPE) results in the death of photoreceptors, leading to a loss of central vision. The RPE is prone to oxidative stress, a factor that together with deteriorating functionality, e.g. decreased intracellular recycling and degradation due to attenuated heterophagy/autophagy, induces inflammation. In the early phases, accumulation of intracellular lipofuscin in the RPE and extracellular drusen between RPE cells and Bruch's membrane can be clinically detected. Subsequently, in dry (atrophic) AMD there is geographic atrophy with discrete areas of RPE loss whereas in the wet (exudative) form there is neovascularization penetrating from the choroid to retinal layers. Elevations in levels of local and systemic biomarkers indicate that chronic inflammation is involved in the pathogenesis of both disease forms.
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Affiliation(s)
- Anu Kauppinen
- Faculty of Health Sciences, School of Pharmacy, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland.
- Department of Ophthalmology, Kuopio University Hospital, Kuopio, Finland.
| | - Jussi J Paterno
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland
| | - Janusz Blasiak
- Department of Molecular Genetics, Faculty of Biology and Environmental Protection, University of Lodz, Lodz, Poland
| | - Antero Salminen
- Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland
| | - Kai Kaarniranta
- Department of Ophthalmology, Kuopio University Hospital, Kuopio, Finland
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland
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112
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van Niel G. Study of Exosomes Shed New Light on Physiology of Amyloidogenesis. Cell Mol Neurobiol 2016; 36:327-42. [DOI: 10.1007/s10571-016-0357-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 02/27/2016] [Indexed: 12/18/2022]
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113
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Forest DL, Johnson LV, Clegg DO. Cellular models and therapies for age-related macular degeneration. Dis Model Mech 2016; 8:421-7. [PMID: 26035859 PMCID: PMC4415892 DOI: 10.1242/dmm.017236] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Age-related macular degeneration (AMD) is a complex neurodegenerative visual disorder that causes profound physical and psychosocial effects. Visual impairment in AMD is caused by the loss of retinal pigmented epithelium (RPE) cells and the light-sensitive photoreceptor cells that they support. There is currently no effective treatment for the most common form of this disease (dry AMD). A new approach to treating AMD involves the transplantation of RPE cells derived from either human embryonic or induced pluripotent stem cells. Multiple clinical trials are being initiated using a variety of cell therapies. Although many animal models are available for AMD research, most do not recapitulate all aspects of the disease, hampering progress. However, the use of cultured RPE cells in AMD research is well established and, indeed, some of the more recently described RPE-based models show promise for investigating the molecular mechanisms of AMD and for screening drug candidates. Here, we discuss innovative cell-culture models of AMD and emerging stem-cell-based therapies for the treatment of this vision-robbing disease. Summary: Here, we discuss the emerging cell-culture models and potential stem-cell-based therapies for AMD, a blinding disorder that affects millions of people worldwide.
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Affiliation(s)
- David L Forest
- Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106-9625, USA
| | - Lincoln V Johnson
- Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106-9625, USA
| | - Dennis O Clegg
- Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106-9625, USA
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Tran TL, Bek T, la Cour M, Prause JU, Hamann S, Heegaard S. Aquaporin-1 Expression in Retinal Pigment Epithelial Cells Overlying Retinal Drusen. Ophthalmic Res 2016; 55:180-4. [DOI: 10.1159/000443207] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 12/07/2015] [Indexed: 11/19/2022]
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Vavvas DG, Daniels AB, Kapsala ZG, Goldfarb JW, Ganotakis E, Loewenstein JI, Young LH, Gragoudas ES, Eliott D, Kim IK, Tsilimbaris MK, Miller JW. Regression of Some High-risk Features of Age-related Macular Degeneration (AMD) in Patients Receiving Intensive Statin Treatment. EBioMedicine 2016; 5:198-203. [PMID: 27077128 PMCID: PMC4816836 DOI: 10.1016/j.ebiom.2016.01.033] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 01/26/2016] [Accepted: 01/27/2016] [Indexed: 12/26/2022] Open
Abstract
Importance Age-related macular degeneration (AMD) remains the leading cause of blindness in developed countries, and affects more than 150 million worldwide. Despite effective anti-angiogenic therapies for the less prevalent neovascular form of AMD, treatments are lacking for the more prevalent dry form. Similarities in risk factors and pathogenesis between AMD and atherosclerosis have led investigators to study the effects of statins on AMD incidence and progression with mixed results. A limitation of these studies has been the heterogeneity of AMD disease and the lack of standardization in statin dosage. Objective We were interested in studying the effects of high-dose statins, similar to those showing regression of atherosclerotic plaques, in AMD. Design Pilot multicenter open-label prospective clinical study of 26 patients with diagnosis of AMD and the presence of many large, soft drusenoid deposits. Patients received 80 mg of atorvastatin daily and were monitored at baseline and every 3 months with complete ophthalmologic exam, best corrected visual acuity (VA), fundus photographs, optical coherence tomography (OCT), and blood work (AST, ALT, CPK, total cholesterol, TSH, creatinine, as well as a pregnancy test for premenopausal women). Results Twenty-three subjects completed a minimum follow-up of 12 months. High-dose atorvastatin resulted in regression of drusen deposits associated with vision gain (+ 3.3 letters, p = 0.06) in 10 patients. No subjects progressed to advanced neovascular AMD. Conclusions High-dose statins may result in resolution of drusenoid pigment epithelial detachments (PEDs) and improvement in VA, without atrophy or neovascularization in a high-risk subgroup of AMD patients. Confirmation from larger studies is warranted. High dose lipophilic statin administration was associated with regression of large soft drusen and vision gain in 10/23 AMD patients. Duration of treatment before a positive response was observed was usually 1–1.5 years. Patients on high-dose statin appeared to be protected from progression to “wet” neovascular-AMD.
There is a lack of effective therapies for dry age-related macular degeneration (AMD), one of the leading causes of blindness affecting millions. Although AMD shares similarities with atherosclerosis, prior studies on statins and AMD have failed to show improvement. A limitation of these studies has been the heterogeneity of AMD disease and the lack of standardization in statin dosage. Here, we present for the first time evidence that treatment with high-dose atorvastatin (80 mg) is associated with regression of lipid deposits and improvement in visual acuity, without atrophy or neovascularization, in high-risk AMD patients.
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Affiliation(s)
- Demetrios G. Vavvas
- Corresponding authors at: 243 Charles St., Boston, MA 02114, USA.243 Charles St.BostonMA02114USA
| | - Anthony B. Daniels
- Corresponding authors at: 243 Charles St., Boston, MA 02114, USA.243 Charles St.BostonMA02114USA
| | | | | | | | | | | | | | | | | | - Miltiadis K. Tsilimbaris
- Corresponding authors at: 243 Charles St., Boston, MA 02114, USA.243 Charles St.BostonMA02114USA
| | - Joan W. Miller
- Corresponding authors at: 243 Charles St., Boston, MA 02114, USA.243 Charles St.BostonMA02114USA
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116
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Common coding variants in the HLA-DQB1 region confer susceptibility to age-related macular degeneration. Eur J Hum Genet 2016; 24:1049-55. [PMID: 26733291 DOI: 10.1038/ejhg.2015.247] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 09/21/2015] [Accepted: 10/15/2015] [Indexed: 11/08/2022] Open
Abstract
Age-related macular degeneration (AMD) risk variants in the complement system point to the important role of immune response and inflammation in the pathogenesis of AMD. Although the human leukocyte antigen (HLA) region has a central role in regulating immune response, previous studies of genetic variation in HLA genes and AMD have been limited by sample size or incomplete coverage of the HLA region by first-generation genotyping arrays and imputation panels. Here, we conducted a large-scale HLA fine-mapping study with 4841 AMD cases and 23 790 controls of non-Hispanic white ancestry from the Kaiser Permanente Genetic Epidemiology Research on Adult Health and Aging cohort. Genotyping was conducted using custom Affymetrix Axiom arrays, with dense coverage of the HLA region. Classic HLA polymorphisms were imputed using SNP2HLA, which utilizes a large reference panel to provide improved imputation accuracy of variants in this region. We examined a total of 6937 SNPs and 172 classical HLA alleles, conditioning on established AMD risk variants, which revealed novel associations with two non-synonymous SNPs in perfect linkage disequilibrium, rs9274390 and rs41563814 (odds ratio (OR)=1.21; P=1.4 × 10(-11)) corresponding to amino-acid changes at position 66 and 67 in HLA-DQB1, respectively, and the DQB1*02 classical HLA allele (OR=1.22; P=3.9 × 10(-10)) with the risk of AMD. We confirmed these association signals, again conditioning on established risk variants, in the MMAP data set of subjects with advanced AMD (rs9274390/rs41563814: OR=1.28; P=1.30 × 10(-3), DQB1*02: OR=1.32; P=9.00 × 10(-4)). These findings support a role of HLA class II alleles in the risk of AMD.
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Abstract
The cholesterol transporting protein apolipoprotein E (ApoE) occurs in three allelic variants in humans unlike in other species. The resulting protein isoforms E2, E3 and E4 exhibit differences in lipid binding, integrating into lipoprotein particles and affinity for lipoprotein receptors. ApoE isoforms confer genetic risk for several diseases of aging including atherosclerosis, Alzheimer's disease, and age-related macular degeneration (AMD). A single E4 allele increases the risk of developing Alzheimer's disease, whereas the E2 allele is protective. Intriguingly, the E4 allele is protective in AMD. Current thinking about different functions of ApoE isoforms comes largely from studies on Alzheimer's disease. These data cannot be directly extrapolated to AMD since the primary cells affected in these diseases (neurons vs. retinal pigment epithelium) are so different. Here, we propose that ApoE serves a fundamentally different purpose in regulating cholesterol homeostasis in the retinal pigment epithelium and this could explain why allelic risk factors are flipped for AMD compared to Alzheimer's disease.
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Haapasalo K, van Kessel K, Nissilä E, Metso J, Johansson T, Miettinen S, Varjosalo M, Kirveskari J, Kuusela P, Chroni A, Jauhiainen M, van Strijp J, Jokiranta TS. Complement Factor H Binds to Human Serum Apolipoprotein E and Mediates Complement Regulation on High Density Lipoprotein Particles. J Biol Chem 2015; 290:28977-87. [PMID: 26468283 DOI: 10.1074/jbc.m115.669226] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Indexed: 11/06/2022] Open
Abstract
The alternative pathway of complement is an important part of the innate immunity response against foreign particles invading the human body. To avoid damage to host cells, it needs to be efficiently down-regulated by plasma factor H (FH) as exemplified by various diseases caused by mutations in its domains 19-20 (FH19-20) and 5-7 (FH5-7). These regions are also the main interaction sites for microbial pathogens that bind host FH to evade complement attack. We previously showed that inhibition of FH binding by a recombinant FH5-7 construct impairs survival of FH binding pathogens in human blood. In this study we found that upon exposure to full blood, the addition of FH5-7 reduces survival of, surprisingly, also those microbes that are not able to bind FH. This effect was mediated by inhibition of complement regulation and subsequently enhanced neutrophil phagocytosis by FH5-7. We found that although FH5-7 does not reduce complement regulation in the actual fluid phase of plasma, it reduces regulation on HDL particles in plasma. Using affinity chromatography and mass spectrometry we revealed that FH interacts with serum apolipoprotein E (apoE) via FH5-7 domains. Furthermore, binding of FH5-7 to HDL was dependent on the concentration of apoE on the HDL particles. These findings explain why the addition of FH5-7 to plasma leads to excessive complement activation and phagocytosis of microbes in full anticoagulated blood. In conclusion, our data show how FH interacts with apoE molecules via domains 5-7 and regulates alternative pathway activation on plasma HDL particles.
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Affiliation(s)
- Karita Haapasalo
- From the Department of Bacteriology and Immunology, Haartman Institute, and Research Programs Unit, Immunobiology, University of Helsinki, FIN-00014 Helsinki, Finland, Medical Microbiology, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands,
| | - Kok van Kessel
- Medical Microbiology, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands
| | - Eija Nissilä
- From the Department of Bacteriology and Immunology, Haartman Institute, and Research Programs Unit, Immunobiology, University of Helsinki, FIN-00014 Helsinki, Finland
| | - Jari Metso
- Department of Molecular Medicine, National Institute for Health and Welfare, Biomedicum, FI-00290 Helsinki, Finland
| | - Tiira Johansson
- From the Department of Bacteriology and Immunology, Haartman Institute, and Research Programs Unit, Immunobiology, University of Helsinki, FIN-00014 Helsinki, Finland
| | - Sini Miettinen
- University of Helsinki, Institute of Biotechnology, 00014 Helsinki, Finland
| | - Markku Varjosalo
- University of Helsinki, Institute of Biotechnology, 00014 Helsinki, Finland
| | - Juha Kirveskari
- HUSLAB, Helsinki University Central Hospital Laboratory, 00290 Helsinki, Finland, and
| | - Pentti Kuusela
- HUSLAB, Helsinki University Central Hospital Laboratory, 00290 Helsinki, Finland, and
| | - Angelika Chroni
- Institute of Biosciences and Applications, National Center for Scientific Research "Demokritos," 15310 Athens, Greece
| | - Matti Jauhiainen
- Department of Molecular Medicine, National Institute for Health and Welfare, Biomedicum, FI-00290 Helsinki, Finland
| | - Jos van Strijp
- Medical Microbiology, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands
| | - T Sakari Jokiranta
- From the Department of Bacteriology and Immunology, Haartman Institute, and Research Programs Unit, Immunobiology, University of Helsinki, FIN-00014 Helsinki, Finland
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119
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Fernandez-Godino R, Garland DL, Pierce EA. A local complement response by RPE causes early-stage macular degeneration. Hum Mol Genet 2015; 24:5555-69. [PMID: 26199322 PMCID: PMC4572070 DOI: 10.1093/hmg/ddv287] [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: 04/13/2015] [Revised: 07/06/2015] [Accepted: 07/13/2015] [Indexed: 01/05/2023] Open
Abstract
Inherited and age-related macular degenerations (AMDs) are important causes of vision loss. An early hallmark of these disorders is the formation of sub-retinal pigment epithelium (RPE) basal deposits. A role for the complement system in MDs was suggested by genetic association studies, but direct functional connections between alterations in the complement system and the pathogenesis of MD remain to be defined. We used primary RPE cells from a mouse model of inherited MD due to a p.R345W mutation in EGF-containing fibulin-like extracellular matrix protein 1 (EFEMP1) to investigate the role of the RPE in early MD pathogenesis. Efemp1(R345W) RPE cells recapitulate the basal deposit formation observed in vivo by producing sub-RPE deposits in vitro. The deposits share features with basal deposits, and their formation was mediated by EFEMP1(R345W) or complement component 3a (C3a), but not by complement component 5a (C5a). Increased activation of complement appears to occur in response to an abnormal extracellular matrix (ECM), generated by the mutant EFEMP1(R345W) protein and reduced ECM turnover due to inhibition of matrix metalloproteinase 2 by EFEMP1(R345W) and C3a. Increased production of C3a also stimulated the release of cytokines such as interleukin (IL)-6 and IL-1B, which appear to have a role in deposit formation, albeit downstream of C3a. These studies provide the first direct indication that complement components produced locally by the RPE are involved in the formation of basal deposits. Furthermore, these results suggest that C3a generated by RPE is a potential therapeutic target for the treatment of EFEMP1-associated MD as well as AMD.
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Affiliation(s)
| | | | - Eric A Pierce
- Ocular Genomics Institute, Department of Ophthalmology and Berman-Gund Laboratory for the Study of Retinal Degenerations, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, USA
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120
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van Niel G, Bergam P, Di Cicco A, Hurbain I, Lo Cicero A, Dingli F, Palmulli R, Fort C, Potier MC, Schurgers LJ, Loew D, Levy D, Raposo G. Apolipoprotein E Regulates Amyloid Formation within Endosomes of Pigment Cells. Cell Rep 2015; 13:43-51. [PMID: 26387950 DOI: 10.1016/j.celrep.2015.08.057] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 07/02/2015] [Accepted: 08/20/2015] [Indexed: 01/20/2023] Open
Abstract
Accumulation of toxic amyloid oligomers is a key feature in the pathogenesis of amyloid-related diseases. Formation of mature amyloid fibrils is one defense mechanism to neutralize toxic prefibrillar oligomers. This mechanism is notably influenced by apolipoprotein E variants. Cells that produce mature amyloid fibrils to serve physiological functions must exploit specific mechanisms to avoid potential accumulation of toxic species. Pigment cells have tuned their endosomes to maximize the formation of functional amyloid from the protein PMEL. Here, we show that ApoE is associated with intraluminal vesicles (ILV) within endosomes and remain associated with ILVs when they are secreted as exosomes. ApoE functions in the ESCRT-independent sorting mechanism of PMEL onto ILVs and regulates the endosomal formation of PMEL amyloid fibrils in vitro and in vivo. This process secures the physiological formation of amyloid fibrils by exploiting ILVs as amyloid nucleating platforms.
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Affiliation(s)
- Guillaume van Niel
- Institut Curie, PSL Research University, UMR144, Centre de Recherche, 26 rue d'ULM, Paris 75231, France; Centre National de la Recherche Scientifique, UMR144, Paris 75248, France; Cell and Tissue Imaging Core Facility PICT-IBiSA, Institut Curie, Paris 75248, France.
| | - Ptissam Bergam
- Institut Curie, PSL Research University, UMR144, Centre de Recherche, 26 rue d'ULM, Paris 75231, France; Centre National de la Recherche Scientifique, UMR144, Paris 75248, France; Cell and Tissue Imaging Core Facility PICT-IBiSA, Institut Curie, Paris 75248, France
| | - Aurelie Di Cicco
- Cell and Tissue Imaging Core Facility PICT-IBiSA, Institut Curie, Paris 75248, France; Institut Curie, PSL Research University, UMR168, Centre de Recherche, 26 rue d'ULM, Paris 75231, France; Centre National de la Recherche Scientifique, UMR 168, Paris 75231, France
| | - Ilse Hurbain
- Institut Curie, PSL Research University, UMR144, Centre de Recherche, 26 rue d'ULM, Paris 75231, France; Centre National de la Recherche Scientifique, UMR144, Paris 75248, France; Cell and Tissue Imaging Core Facility PICT-IBiSA, Institut Curie, Paris 75248, France
| | - Alessandra Lo Cicero
- Institut Curie, PSL Research University, UMR144, Centre de Recherche, 26 rue d'ULM, Paris 75231, France; Centre National de la Recherche Scientifique, UMR144, Paris 75248, France
| | - Florent Dingli
- Institut Curie, PSL Research University, Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, Paris 75248, France
| | - Roberta Palmulli
- Institut Curie, PSL Research University, UMR144, Centre de Recherche, 26 rue d'ULM, Paris 75231, France; Centre National de la Recherche Scientifique, UMR144, Paris 75248, France
| | - Cecile Fort
- Institut Curie, PSL Research University, UMR144, Centre de Recherche, 26 rue d'ULM, Paris 75231, France; Centre National de la Recherche Scientifique, UMR144, Paris 75248, France
| | - Marie Claude Potier
- Institut du Cerveau et de la Moelle, CNRS UMR7225, INSERM U1127, UPMC Hôpital de la Pitié-Salpêtrière, 47 Bd de l'Hôpital, Paris 75013, France
| | - Leon J Schurgers
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, P.O. Box 616, 6200 MD Maastricht, the Netherlands
| | - Damarys Loew
- Institut Curie, PSL Research University, Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, Paris 75248, France
| | - Daniel Levy
- Cell and Tissue Imaging Core Facility PICT-IBiSA, Institut Curie, Paris 75248, France; Institut Curie, PSL Research University, UMR168, Centre de Recherche, 26 rue d'ULM, Paris 75231, France; Centre National de la Recherche Scientifique, UMR 168, Paris 75231, France
| | - Graça Raposo
- Institut Curie, PSL Research University, UMR144, Centre de Recherche, 26 rue d'ULM, Paris 75231, France; Centre National de la Recherche Scientifique, UMR144, Paris 75248, France; Cell and Tissue Imaging Core Facility PICT-IBiSA, Institut Curie, Paris 75248, France
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121
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Zanzottera EC, Messinger JD, Ach T, Smith RT, Freund KB, Curcio CA. The Project MACULA Retinal Pigment Epithelium Grading System for Histology and Optical Coherence Tomography in Age-Related Macular Degeneration. Invest Ophthalmol Vis Sci 2015; 56:3253-68. [PMID: 25813989 DOI: 10.1167/iovs.15-16431] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
PURPOSE To seek pathways of retinal pigment epithelium (RPE) fate in age-related macular degeneration via a morphology grading system; provide nomenclature, visualization targets, and metrics for clinical imaging and model systems. METHODS Donor eyes with geographic atrophy (GA) or choroidal neovascularization (CNV) and one GA eye with previous clinical spectral-domain optical coherence tomography (SDOCT) imaging were processed for histology, photodocumented, and annotated at predefined locations. Retinal pigment epithelial cells contained spindle-shaped melanosomes, apposed a basal lamina or basal laminar deposit (BLamD), and exhibited recognizable morphologies. Thicknesses and unbiased estimates of frequencies were obtained. RESULTS In 13 GA eyes (449 locations), 'Shedding,' 'Sloughed,' and 'Dissociated' morphologies were abundant; 22.2% of atrophic locations had 'Dissociated' RPE. In 39 CNV eyes (1363 locations), 37.3% of locations with fibrovascular/fibrocellular scar had 'Entombed' RPE; 'Sloughed,' 'Dissociated,' and 'Bilaminar' morphologies were abundant. Of abnormal RPE, CNV and GA both had ~35% 'Sloughed'/'Intraretinal,' with more Intraretinal in CNV (9.5% vs. 1.8%). 'Shedding' cells associated with granule aggregations in BLamD. The RPE layer did not thin, and BLamD remained thick, with progression. Granule-containing material consistent with three morphologies correlated to SDOCT hyperreflective foci in the previously examined GA patient. CONCLUSIONS Retinal pigment epithelium morphology indicates multiple pathways in GA and CNV. Atrophic/scarred areas have numerous cells capable of transcribing genes and generating imaging signals. Shed granule aggregates, possibly apoptotic, are visible in SDOCT, as are 'Dissociated' and 'Sloughed' cells. The significance of RPE phenotypes is addressable in longitudinal, high-resolution imaging in clinic populations. Data can motivate future molecular phenotyping studies.
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Affiliation(s)
- Emma C Zanzottera
- Department of Ophthalmology University of Alabama School of Medicine, Birmingham, Alabama, United States 2Eye Clinic, Department of Clinical Science "Luigi Sacco," Sacco Hospital, University of Milan, Milan, Italy
| | - Jeffrey D Messinger
- Department of Ophthalmology University of Alabama School of Medicine, Birmingham, Alabama, United States
| | - Thomas Ach
- Department of Ophthalmology University of Alabama School of Medicine, Birmingham, Alabama, United States 3University Hospital Würzburg, Department of Ophthalmology, Würzburg, Germany
| | - R Theodore Smith
- Department of Ophthalmology, New York University School of Medicine, New York City, New York, United States
| | - K Bailey Freund
- Department of Ophthalmology, New York University School of Medicine, New York City, New York, United States 5Vitreous Retina Macula Consultants of New York, New York, New York, United States 6LuEsther T. Mertz Retinal Research Center, Manhattan Eye, Ear
| | - Christine A Curcio
- Department of Ophthalmology University of Alabama School of Medicine, Birmingham, Alabama, United States
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122
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Levy O, Calippe B, Lavalette S, Hu SJ, Raoul W, Dominguez E, Housset M, Paques M, Sahel JA, Bemelmans AP, Combadiere C, Guillonneau X, Sennlaub F. Apolipoprotein E promotes subretinal mononuclear phagocyte survival and chronic inflammation in age-related macular degeneration. EMBO Mol Med 2015; 7:211-26. [PMID: 25604058 PMCID: PMC4328649 DOI: 10.15252/emmm.201404524] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Physiologically, the retinal pigment epithelium (RPE) expresses immunosuppressive signals such as FAS ligand (FASL), which prevents the accumulation of leukocytes in the subretinal space. Age-related macular degeneration (AMD) is associated with a breakdown of the subretinal immunosuppressive environment and chronic accumulation of mononuclear phagocytes (MPs). We show that subretinal MPs in AMD patients accumulate on the RPE and express high levels of APOE. MPs of Cx3cr1(-/-) mice that develop MP accumulation on the RPE, photoreceptor degeneration, and increased choroidal neovascularization similarly express high levels of APOE. ApoE deletion in Cx3cr1(-/-) mice prevents pathogenic age- and stress-induced subretinal MP accumulation. We demonstrate that increased APOE levels induce IL-6 in MPs via the activation of the TLR2-CD14-dependent innate immunity receptor cluster. IL-6 in turn represses RPE FasL expression and prolongs subretinal MP survival. This mechanism may account, in part, for the MP accumulation observed in Cx3cr1(-/-) mice. Our results underline the inflammatory role of APOE in sterile inflammation in the immunosuppressive subretinal space. They provide rationale for the implication of IL-6 in AMD and open avenues toward therapies inhibiting pathogenic chronic inflammation in late AMD.
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Affiliation(s)
- Olivier Levy
- INSERM, Paris, France UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts INSERM-DHOS CIC 503, Paris, France
| | - Bertrand Calippe
- INSERM, Paris, France UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts INSERM-DHOS CIC 503, Paris, France
| | - Sophie Lavalette
- INSERM, Paris, France UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts INSERM-DHOS CIC 503, Paris, France
| | - Shulong J Hu
- INSERM, Paris, France UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts INSERM-DHOS CIC 503, Paris, France
| | - William Raoul
- INSERM, Paris, France UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts INSERM-DHOS CIC 503, Paris, France
| | - Elisa Dominguez
- INSERM, Paris, France UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts INSERM-DHOS CIC 503, Paris, France
| | - Michael Housset
- INSERM, Paris, France UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts INSERM-DHOS CIC 503, Paris, France
| | - Michel Paques
- INSERM, Paris, France UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts INSERM-DHOS CIC 503, Paris, France
| | - José-Alain Sahel
- INSERM, Paris, France UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts INSERM-DHOS CIC 503, Paris, France
| | - Alexis-Pierre Bemelmans
- INSERM, Paris, France UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts INSERM-DHOS CIC 503, Paris, France CEA DSV I²BM Molecular Imaging Research Center (MIRCen), Fontenay-aux-Roses, France CNRS CEA URA 2210, Fontenay-aux-Roses, France
| | - Christophe Combadiere
- Sorbonne Universités, UPMC Univ Paris 06 CR7 Centre d'Immunologie et des Maladies Infectieuses (CIMI-Paris), Paris, France INSERM U1135 CIMI-Paris, Paris, France CNRS ERL 8255 CIMI-Paris, Paris, France
| | - Xavier Guillonneau
- INSERM, Paris, France UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts INSERM-DHOS CIC 503, Paris, France
| | - Florian Sennlaub
- INSERM, Paris, France UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts INSERM-DHOS CIC 503, Paris, France
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7-Ketocholesterol increases retinal microglial migration, activation, and angiogenicity: a potential pathogenic mechanism underlying age-related macular degeneration. Sci Rep 2015; 5:9144. [PMID: 25775051 PMCID: PMC4360733 DOI: 10.1038/srep09144] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 02/23/2015] [Indexed: 11/26/2022] Open
Abstract
Age-related macular degeneration (AMD) has been associated with both accumulation of lipid and lipid oxidative products, as well as increased neuroinflammatory changes and microglial activation in the outer retina. However, the relationships between these factors are incompletely understood. 7-Ketocholesterol (7KCh) is a cholesterol oxidation product localized to the outer retina with prominent pro-inflammatory effects. To explore the potential relationship between 7KCh and microglial activation, we localized 7KCh and microglia to the outer retina of aged mice and investigated 7KCh effects on retinal microglia in both in vitro and in vivo systems. We found that retinal microglia demonstrated a prominent chemotropism to 7KCh and readily internalized 7KCh. Sublethal concentrations of 7KCh resulted in microglial activation and polarization to a pro-inflammatory M1 state via NLRP3 inflammasome activation. Microglia exposed to 7KCh reduced expression of neurotrophic growth factors but increased expression of angiogenic factors, transitioning to a more neurotoxic and pro-angiogenic phenotype. Finally, subretinal transplantation of 7KCh-exposed microglia promoted choroidal neovascularization (CNV) relative to control microglia in a Matrigel-CNV model. The interaction of retinal microglia with 7KCh in the aged retina may thus underlie how outer retinal lipid accumulation in intermediate AMD results in neuroinflammation that ultimately drives progression towards advanced AMD.
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Whitmore SS, Sohn EH, Chirco KR, Drack AV, Stone EM, Tucker BA, Mullins RF. Complement activation and choriocapillaris loss in early AMD: implications for pathophysiology and therapy. Prog Retin Eye Res 2015; 45:1-29. [PMID: 25486088 PMCID: PMC4339497 DOI: 10.1016/j.preteyeres.2014.11.005] [Citation(s) in RCA: 159] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 11/19/2014] [Accepted: 11/25/2014] [Indexed: 12/24/2022]
Abstract
Age-related macular degeneration (AMD) is a common and devastating disease that can result in severe visual dysfunction. Over the last decade, great progress has been made in identifying genetic variants that contribute to AMD, many of which lie in genes involved in the complement cascade. In this review we discuss the significance of complement activation in AMD, particularly with respect to the formation of the membrane attack complex in the aging choriocapillaris. We review the clinical, histological and biochemical data that indicate that vascular loss in the choroid occurs very early in the pathogenesis of AMD, and discuss the potential impact of vascular dropout on the retinal pigment epithelium, Bruch's membrane and the photoreceptor cells. Finally, we present a hypothesis for the pathogenesis of early AMD and consider the implications of this model on the development of new therapies.
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Affiliation(s)
- S Scott Whitmore
- The Stephen A. Wynn Institute for Vision Research, The University of Iowa, United States; Department of Ophthalmology and Visual Sciences, The University of Iowa, United States
| | - Elliott H Sohn
- The Stephen A. Wynn Institute for Vision Research, The University of Iowa, United States; Department of Ophthalmology and Visual Sciences, The University of Iowa, United States
| | - Kathleen R Chirco
- The Stephen A. Wynn Institute for Vision Research, The University of Iowa, United States; Department of Ophthalmology and Visual Sciences, The University of Iowa, United States
| | - Arlene V Drack
- The Stephen A. Wynn Institute for Vision Research, The University of Iowa, United States; Department of Ophthalmology and Visual Sciences, The University of Iowa, United States
| | - Edwin M Stone
- The Stephen A. Wynn Institute for Vision Research, The University of Iowa, United States; Department of Ophthalmology and Visual Sciences, The University of Iowa, United States
| | - Budd A Tucker
- The Stephen A. Wynn Institute for Vision Research, The University of Iowa, United States; Department of Ophthalmology and Visual Sciences, The University of Iowa, United States
| | - Robert F Mullins
- The Stephen A. Wynn Institute for Vision Research, The University of Iowa, United States; Department of Ophthalmology and Visual Sciences, The University of Iowa, United States
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125
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Kobayashi H, Okamoto H, Murakami A, Iwata T. Plasma proteome analysis on cynomolgus monkey (Macaca fascicularis) pedigrees with early onset drusen formation. Exp Anim 2015; 63:305-10. [PMID: 25077760 PMCID: PMC4206734 DOI: 10.1538/expanim.63.305] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The central region of the primate retina is called macula. The fovea is located at the center of the macula, where the photoreceptors are concentrated to create neural network adapted for high visual acuity. Damage to the fovea by macular dystrophies and age-related macular degeneration (AMD) can reduce the central visual acuity. The molecular mechanisms leading to these diseases are most likely dependent on the proteins in macula differ from that in peripheral retina in expression level. Previously, we reported an early onset macular degeneration with drusen in cynomolgus monkey pedigrees. These monkeys show similar fundus findings of early stage of AMD at 2 years after birth. To elucidate mechanism of drusen formation and to find disease biomarkers for early stage of AMD, we performed plasma proteome analysis. Plasma samples were collected from four affected and control monkeys within the same pedigree. Successful fractionation of the plasma proteins by ProteoMiner and Gelfree8100 were confirmed by SDS-PAGE. Total of 245 proteins were identified from eight samples. From the results of spectral counting, we selected some proteins, Apolipoprotein E, Histidine-rich glycoprotein, and Retinol-binding protein 4 as candidate proteins that would be related with drusen formation. Candidate proteins would be potentially beneficial as biomarkers for human AMD. One of the identified proteins, Apolipoprotein E (ApoE), is structural component of drusen and also related with other neurodegenerative disease like Alzheimer disease. In this plasma proteome analysis, ApoE would be one of the possible factors of early drusen formation in these cynomolgus monkey pedigrees.
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Affiliation(s)
- Hiroaki Kobayashi
- Division of Molecular &Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro-ku, Tokyo 152-8902, Japan
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126
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Gorham R, Forest DL, Khoury GA, Smadbeck J, Beecher CN, Healy ED, Tamamis P, Archontis G, Larive C, Floudas CA, Radeke MJ, Johnson LV, Morikis D. New compstatin peptides containing N-terminal extensions and non-natural amino acids exhibit potent complement inhibition and improved solubility characteristics. J Med Chem 2015; 58:814-26. [PMID: 25494040 PMCID: PMC4306506 DOI: 10.1021/jm501345y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Indexed: 01/21/2023]
Abstract
Compstatin peptides are complement inhibitors that bind and inhibit cleavage of complement C3. Peptide binding is enhanced by hydrophobic interactions; however, poor solubility promotes aggregation in aqueous environments. We have designed new compstatin peptides derived from the W4A9 sequence (Ac-ICVWQDWGAHRCT-NH2, cyclized between C2 and C12), based on structural, computational, and experimental studies. Furthermore, we developed and utilized a computational framework for the design of peptides containing non-natural amino acids. These new compstatin peptides contain polar N-terminal extensions and non-natural amino acid substitutions at positions 4 and 9. Peptides with α-modified non-natural alanine analogs at position 9, as well as peptides containing only N-terminal polar extensions, exhibited similar activity compared to W4A9, as quantified via ELISA, hemolytic, and cell-based assays, and showed improved solubility, as measured by UV absorbance and reverse-phase HPLC experiments. Because of their potency and solubility, these peptides are promising candidates for therapeutic development in numerous complement-mediated diseases.
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Affiliation(s)
- Ronald
D. Gorham
- Department
of Bioengineering, University of California, Riverside, California 92521, United States
| | - David L. Forest
- Center
for the Study of Macular Degeneration, Neuroscience Research Institute, University of California, Santa Barbara, California 93106, United States
| | - George A. Khoury
- Department
of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - James Smadbeck
- Department
of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Consuelo N. Beecher
- Department
of Chemistry, University of California, Riverside, California 92521, United States
| | - Evangeline D. Healy
- Center
for the Study of Macular Degeneration, Neuroscience Research Institute, University of California, Santa Barbara, California 93106, United States
| | - Phanourios Tamamis
- Department
of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
- Department
of Physics, University of Cyprus, PO20537, CY1678 Nicosia, Cyprus
| | - Georgios Archontis
- Department
of Physics, University of Cyprus, PO20537, CY1678 Nicosia, Cyprus
| | - Cynthia
K. Larive
- Department
of Chemistry, University of California, Riverside, California 92521, United States
| | - Christodoulos A. Floudas
- Department
of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Monte J. Radeke
- Center
for the Study of Macular Degeneration, Neuroscience Research Institute, University of California, Santa Barbara, California 93106, United States
| | - Lincoln V. Johnson
- Center
for the Study of Macular Degeneration, Neuroscience Research Institute, University of California, Santa Barbara, California 93106, United States
| | - Dimitrios Morikis
- Department
of Bioengineering, University of California, Riverside, California 92521, United States
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127
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Identification of hydroxyapatite spherules provides new insight into subretinal pigment epithelial deposit formation in the aging eye. Proc Natl Acad Sci U S A 2015; 112:1565-70. [PMID: 25605911 DOI: 10.1073/pnas.1413347112] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Accumulation of protein- and lipid-containing deposits external to the retinal pigment epithelium (RPE) is common in the aging eye, and has long been viewed as the hallmark of age-related macular degeneration (AMD). The cause for the accumulation and retention of molecules in the sub-RPE space, however, remains an enigma. Here, we present fluorescence microscopy and X-ray diffraction evidence for the formation of small (0.5-20 μm in diameter), hollow, hydroxyapatite (HAP) spherules in Bruch's membrane in human eyes. These spherules are distinct in form, placement, and staining from the well-known calcification of the elastin layer of the aging Bruch's membrane. Secondary ion mass spectrometry (SIMS) imaging confirmed the presence of calcium phosphate in the spherules and identified cholesterol enrichment in their core. Using HAP-selective fluorescent dyes, we show that all types of sub-RPE deposits in the macula, as well as in the periphery, contain numerous HAP spherules. Immunohistochemical labeling for proteins characteristic of sub-RPE deposits, such as complement factor H, vitronectin, and amyloid beta, revealed that HAP spherules were coated with these proteins. HAP spherules were also found outside the sub-RPE deposits, ready to bind proteins at the RPE/choroid interface. Based on these results, we propose a novel mechanism for the growth, and possibly even the formation, of sub-RPE deposits, namely, that the deposit growth and formation begin with the deposition of insoluble HAP shells around naturally occurring, cholesterol-containing extracellular lipid droplets at the RPE/choroid interface; proteins and lipids then attach to these shells, initiating or supporting the growth of sub-RPE deposits.
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128
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Yu B, Xu P, Zhao Z, Cai J, Sternberg P, Chen Y. Subcellular distribution and activity of mechanistic target of rapamycin in aged retinal pigment epithelium. Invest Ophthalmol Vis Sci 2014; 55:8638-50. [PMID: 25491300 DOI: 10.1167/iovs.14-14758] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Inhibiting mechanistic target of rapamycin (mTOR) by pharmacological or genetic approaches can extend lifespan in mammals. The kinase activity of mTOR is controlled by upstream regulatory proteins and its subcellular localization. The purpose of this study was to characterize age-related alterations and functional consequences of mTOR signaling in the postmitotic RPE cells. METHODS Activity of mTOR complex 1 (mTORC1) was monitored by measuring phosphorylation status of its downstream effector protein S6, in either cultured human RPE cells or RPE explants prepared from mice at different ages. Subcellular distribution of mTOR was investigated by immunofluorescent staining of RPE culture or flatmount. The signaling of mTORC1 was modulated by either overexpression of a small guanosine triphosphatase, Ras homolog enriched in brain (Rheb), or disruption of the Ragulator complex with small interference RNA targeting p18. The effects of mTOR pathway on degradation of phagocytosed photoreceptor outer segments (POS) were determined by measuring the turnover rate of rhodopsin. RESULTS Aged RPE cells had more lysosome-associated mTOR and had increased response to amino acid stimulation. The lysosome distribution was essential for mTORC1 function, as disruption of the Ragulator complex abolished mTORC1 activation by amino acids. Increased mTORC1 activity caused decreased rate of degradation of internalized POS in the RPE. CONCLUSIONS Aging changes the subcellular localization and function of mTOR in the RPE. Increased mTORC1 inhibits POS degradation and may further exacerbate lysosome dysfunction of aged RPE.
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Affiliation(s)
- Bo Yu
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, Texas, United States
| | - Pei Xu
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, Texas, United States
| | - Zhenyang Zhao
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, Texas, United States
| | - Jiyang Cai
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, Texas, United States
| | - Paul Sternberg
- Vanderbilt Eye Institute, Vanderbilt University, Nashville, Tennessee, United States
| | - Yan Chen
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, Texas, United States
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129
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Ma W, Paik DC, Barile GR. Bioactive lysophospholipids generated by hepatic lipase degradation of lipoproteins lead to complement activation via the classical pathway. Invest Ophthalmol Vis Sci 2014; 55:6187-93. [PMID: 25205869 DOI: 10.1167/iovs.14-14352] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We determined bioactivity of lysophospholipids generated by degradation of the low-density (LDL), very low-density (VLDL), and high-density (HDL) lipoproteins with hepatic lipase (HL), cholesterol esterase (CE), and lipoprotein-associated phospholipase A2 (Lp-PLA2). METHODS The LDL, VLDL, and HDL were treated with HL, CE, and Lp-PLA2 after immobilization on plates, and complement activation studies were performed with diluted human serum. Complement component 3 (C3) fixation, a marker for complement activation, was determined with a monoclonal anti-human C3d antibody. Enzymatic properties of HL and CE were assayed with triglyceride and phosphatidylcholine substrates for triglyceride hydrolase and phospholipase A activities. The ARPE-19 cells were used for viability studies. RESULTS The HL degradation of human lipoproteins LDL, VLDL, or HDL results in the formation of modified lipoproteins that can activate the complement pathway. Complement activation is dose- and time-dependent upon HL and occurs via the classical pathway. Enzymatic studies suggest that the phospholipase A1 activity of HL generates complement-activating lysophospholipids. C-reactive protein (CRP), known to simultaneously interact with complement C1 and complement factor H (CFH), further enhances HL-induced complement activation. The lysophospholipids, 1-Palmitoyl-sn-glycero-3-phosphocholine and 1-Oleoyl-sn-glycero-3-phosphocholine, can be directly cytotoxic to ARPE-19 cells. CONCLUSIONS The HL degradation of lipoproteins, known to accumulate in the outer retina and in drusen, can lead to the formation of bioactive lysophospholipids that can trigger complement activation and induce RPE cellular dysfunction. Given the known risk associations for age-related macular degeneration (AMD) with HL, CRP, and CFH, this study elucidates a possible damage pathway for age-related macular degeneration (AMD) in genetically predisposed individuals, that HL activity may lead to accumulation of lysophospholipids to initiate complement activation, with CFH dysregulation exacerbating the effects of this process.
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Affiliation(s)
- Wanchao Ma
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - David C Paik
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - Gaetano R Barile
- Department of Ophthalmology, Columbia University, New York, New York, United States
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130
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Mullins RF, Schoo DP, Sohn EH, Flamme-Wiese MJ, Workamelahu G, Johnston RM, Wang K, Tucker BA, Stone EM. The membrane attack complex in aging human choriocapillaris: relationship to macular degeneration and choroidal thinning. THE AMERICAN JOURNAL OF PATHOLOGY 2014; 184:3142-53. [PMID: 25204844 DOI: 10.1016/j.ajpath.2014.07.017] [Citation(s) in RCA: 163] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 06/18/2014] [Accepted: 07/10/2014] [Indexed: 01/19/2023]
Abstract
Age-related macular degeneration (AMD) is a common disease that can result in severe visual impairment. Abnormal regulation of the complement system has been implicated in its pathogenesis, and CFH polymorphisms contribute substantially to risk. How these polymorphisms exert their effects is poorly understood. We performed enzyme-linked immunosorbent assay (ELISA) analysis on young, aged, and AMD choroids to determine the abundance of the membrane attack complex (MAC) and performed immunofluorescence studies on eyes from 117 donors to evaluate the MAC in aging, early AMD, and advanced AMD. Morphometric studies were performed on eyes with high- or low-risk CFH genotypes. ELISA confirmed that MAC increases significantly with aging and with AMD. MAC was localized to Bruch's membrane and the choriocapillaris and was detectable at low levels as early as 5 years of age. Hard drusen were labeled with anti-MAC antibody, but large or confluent drusen and basal deposits were generally unlabeled. Labeling of retinal pigment epithelium was observed in some cases of advanced AMD, but not in early disease. Eyes homozygous for the high-risk CFH genotype had thinner choroids than low-risk homozygotes (P < 0.05). These findings suggest that increased complement activation in AMD and in high-risk genotypes can lead to loss of endothelial cells in early AMD. Treatments to protect the choriocapillaris in early AMD are needed.
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Affiliation(s)
- Robert F Mullins
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, Iowa; Stephen A. Wynn Institute for Vision Research, The University of Iowa, Iowa City, Iowa.
| | - Desi P Schoo
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, Iowa; Stephen A. Wynn Institute for Vision Research, The University of Iowa, Iowa City, Iowa
| | - Elliott H Sohn
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, Iowa; Stephen A. Wynn Institute for Vision Research, The University of Iowa, Iowa City, Iowa
| | - Miles J Flamme-Wiese
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, Iowa; Stephen A. Wynn Institute for Vision Research, The University of Iowa, Iowa City, Iowa
| | - Grefachew Workamelahu
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, Iowa; Stephen A. Wynn Institute for Vision Research, The University of Iowa, Iowa City, Iowa
| | - Rebecca M Johnston
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, Iowa; Stephen A. Wynn Institute for Vision Research, The University of Iowa, Iowa City, Iowa
| | - Kai Wang
- Stephen A. Wynn Institute for Vision Research, The University of Iowa, Iowa City, Iowa; Department of Biostatistics, The University of Iowa, Iowa City, Iowa
| | - Budd A Tucker
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, Iowa; Stephen A. Wynn Institute for Vision Research, The University of Iowa, Iowa City, Iowa
| | - Edwin M Stone
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, Iowa; Stephen A. Wynn Institute for Vision Research, The University of Iowa, Iowa City, Iowa
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131
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Kawa MP, Machalinska A, Roginska D, Machalinski B. Complement system in pathogenesis of AMD: dual player in degeneration and protection of retinal tissue. J Immunol Res 2014; 2014:483960. [PMID: 25276841 PMCID: PMC4168147 DOI: 10.1155/2014/483960] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 07/18/2014] [Accepted: 08/01/2014] [Indexed: 12/25/2022] Open
Abstract
Age-related macular degeneration (AMD) is the most common cause of blindness among the elderly, especially in Western countries. Although the prevalence, risk factors, and clinical course of the disease are well described, its pathogenesis is not entirely elucidated. AMD is associated with a variety of biochemical abnormalities, including complement components deposition in the retinal pigment epithelium-Bruch's membrane-choriocapillaris complex. Although the complement system (CS) is increasingly recognized as mediating important roles in retinal biology, its particular role in AMD pathogenesis has not been precisely defined. Unrestricted activation of the CS following injury may directly damage retinal tissue and recruit immune cells to the vicinity of active complement cascades, therefore detrimentally causing bystander damage to surrounding cells and tissues. On the other hand, recent evidence supports the notion that an active complement pathway is a necessity for the normal maintenance of the neurosensory retina. In this scenario, complement activation appears to have beneficial effect as it promotes cell survival and tissue remodeling by facilitating the rapid removal of dying cells and resulting cellular debris, thus demonstrating anti-inflammatory and neuroprotective activities. In this review, we discuss both the beneficial and detrimental roles of CS in degenerative retina, focusing on the diverse aspects of CS functions that may promote or inhibit macular disease.
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Affiliation(s)
- Milosz P. Kawa
- Department of General Pathology, Pomeranian Medical University, Al. Powstancow Wlkp. 72, 70-111 Szczecin, Poland
| | - Anna Machalinska
- Department of Ophthalmology, Pomeranian Medical University, Al. Powstancow Wlkp. 72, 70-111 Szczecin, Poland
- Department of Histology and Embryology, Pomeranian Medical University, Al. Powstancow Wlkp. 72, 70-111 Szczecin, Poland
| | - Dorota Roginska
- Department of General Pathology, Pomeranian Medical University, Al. Powstancow Wlkp. 72, 70-111 Szczecin, Poland
| | - Boguslaw Machalinski
- Department of General Pathology, Pomeranian Medical University, Al. Powstancow Wlkp. 72, 70-111 Szczecin, Poland
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132
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Kunchithapautham K, Atkinson C, Rohrer B. Smoke exposure causes endoplasmic reticulum stress and lipid accumulation in retinal pigment epithelium through oxidative stress and complement activation. J Biol Chem 2014; 289:14534-46. [PMID: 24711457 PMCID: PMC4031511 DOI: 10.1074/jbc.m114.564674] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 04/02/2014] [Indexed: 01/02/2023] Open
Abstract
Age-related macular degeneration (AMD) is a complex disease caused by genetic and environmental factors, including genetic variants in complement components and smoking. Smoke exposure leads to oxidative stress, complement activation, endoplasmic reticulum (ER) stress, and lipid dysregulation, which have all been proposed to be associated with AMD pathogenesis. Here we examine the effects of smoke exposure on the retinal pigment epithelium (RPE). Mice were exposed to cigarette smoke or filtered air for 6 months. RPE cells grown as stable monolayers were exposed to 5% cigarette smoke extract (CSE). Effects of smoke were determined by biochemical, molecular, and histological measures. Effects of the alternative pathway (AP) of complement and complement C3a anaphylatoxin receptor signaling were analyzed using knock-out mice or specific inhibitors. ER stress markers were elevated after smoke exposure in RPE of intact mice, which was eliminated in AP-deficient mice. To examine this relationship further, RPE monolayers were exposed to CSE. Short term smoke exposure resulted in production and release of complement C3, the generation of C3a, oxidative stress, complement activation on the cell membrane, and ER stress. Long term exposure to CSE resulted in lipid accumulation, and secretion. All measures were reversed by blocking C3a complement receptor (C3aR), alternative complement pathway signaling, and antioxidant therapy. Taken together, our results provide clear evidence that smoke exposure results in oxidative stress and complement activation via the AP, resulting in ER stress-mediated lipid accumulation, and further suggesting that oxidative stress and complement act synergistically in the pathogenesis of AMD.
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Affiliation(s)
| | - Carl Atkinson
- Microbiology and Immunology, Medical University of South Carolina, Charleston, South Carolina 29425 and
| | - Bärbel Rohrer
- From the Departments of Ophthalmology and the Research Service, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401
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133
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Pauly D, Nagel BM, Reinders J, Killian T, Wulf M, Ackermann S, Ehrenstein B, Zipfel PF, Skerka C, Weber BHF. A novel antibody against human properdin inhibits the alternative complement system and specifically detects properdin from blood samples. PLoS One 2014; 9:e96371. [PMID: 24797388 PMCID: PMC4010523 DOI: 10.1371/journal.pone.0096371] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 04/05/2014] [Indexed: 12/13/2022] Open
Abstract
The complement system is an essential part of the innate immune system by acting as a first line of defense which is stabilized by properdin, the sole known positive regulator of the alternative complement pathway. Dysregulation of complement can promote a diversity of human inflammatory diseases which are treated by complement inhibitors. Here, we generated a novel blocking monoclonal antibody (mAb) against properdin and devised a new diagnostic assay for this important complement regulator. Mouse mAb 1340 specifically detected native properdin from human samples with high avidity. MAb 1340 inhibited specifically the alternative complement mediated cell lysis within a concentration range of 1-10 µg/mL. Thus, in vitro anti-properdin mAb 1340 was up to fifteen times more efficient in blocking the complement system as compared to anti-C5 or anti-Ba antibodies. Computer-assisted modelling suggested a three-dimensional binding epitope in a properdin-C3(H2O)-clusterin complex to be responsible for the inhibition. Recovery of properdin in a newly established sandwich ELISA using mAb 1340 was determined at 80-125% for blood sample dilutions above 1∶50. Reproducibility assays showed a variation below 25% at dilutions less than 1∶1,000. Systemic properdin concentrations of healthy controls and patients with age-related macular degeneration or rheumatic diseases were all in the range of 13-30 µg/mL and did not reveal significant differences. These initial results encourage further investigation into the functional role of properdin in the development, progression and treatment of diseases related to the alternative complement pathway. Thus, mAb 1340 represents a potent properdin inhibitor suitable for further research to understand the exact mechanisms how properdin activates the complement C3-convertase and to determine quantitative levels of properdin in biological samples.
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Affiliation(s)
- Diana Pauly
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Benedikt M. Nagel
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Jörg Reinders
- Institute of Functional Genomics, University of Regensburg, Regensburg, Germany
| | - Tobias Killian
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Matthias Wulf
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Susanne Ackermann
- Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Jena, Germany
| | - Boris Ehrenstein
- Klinik und Poliklinik für Rheumatologie und Klinische Immunologie, Asklepios Klinikum Bad Abbach, Bad Abbach, Germany
| | - Peter F. Zipfel
- Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Jena, Germany
- Department of Infection Biology, Friedrich Schiller University, Jena, Germany
| | - Christine Skerka
- Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Jena, Germany
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134
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Abstract
The formation of extracellular deposits known as drusen below the macular region of the retina correlates with increased risk of severe visual loss from age-related macular degeneration (AMD). Inflammation and complement dysregulation contribute to AMD progression; however, disease mechanisms remain incompletely defined. Multiple genetic and environmental factors influence AMD pathology, and although immune system processes play a central role, multiple molecular mechanisms appear to be involved. Drusen proteomics, including the analyses of constituent proteins, oxidative protein modifications, and pattern recognition receptors, provide a foundation for deciphering mechanisms of drusen biogenesis and AMD pathology.
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Affiliation(s)
- John W Crabb
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio 44195
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135
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Doudevski I, Rostagno A, Cowman M, Liebmann J, Ritch R, Ghiso J. Clusterin and complement activation in exfoliation glaucoma. Invest Ophthalmol Vis Sci 2014; 55:2491-9. [PMID: 24550356 DOI: 10.1167/iovs.13-12941] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
PURPOSE The study was done to better understand the biological significance of clusterin co-localization with the exfoliation deposits (XF deposits), and provide insight into a pathogenic mechanism involving activation of the complement system and its pro-inflammatory consequences in patients with exfoliation glaucoma. METHODS Exfoliation lens deposits were analyzed by high resolution atomic force microscopy imaging and confocal immunofluorescence. Levels of clusterin and vitronectin, as well as of the complement activation products C3a and soluble C5b-9, were assessed via ELISA. RESULTS Atomic-force microscopy examination of lenses with exfoliation syndrome (XFS) revealed a dense fibrillar network on the anterior, aqueous-bathed surface of the lens, while the epithelial side displayed no discernible structural features at the same resolution. Clusterin colocalized with XF deposits, demonstrating integral association with the fibrils. Levels of activation-derived complement components C3a and soluble C5b-9, as well as the complement inhibitors clusterin and vitronectin, were found significantly elevated (1.7-fold, P < 0.05; 4.1-fold, P < 0.05; 1.8-fold, P < 0.01; and 3.0-fold, P < 0.01, respectively) in aqueous humor from glaucoma patients with XFS compared to non-XFS glaucoma controls. CONCLUSIONS The data provide compelling evidence for the activation of the complement system in XFS, highlighting the generation of subproducts with potent proinflammatory activity, which are capable of triggering and chronically maintaining levels of subclinical inflammation, suggesting novel targets for therapeutic intervention. The colocalization of clusterin in exfoliation fibrils suggests a failed attempt to prevent tissue accumulation of protein aggregates, as seen in other protein folding disorders, likely due to the abnormal high levels of misfolded proteins overwhelming its chaperone capacity.
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Affiliation(s)
- Ivo Doudevski
- Department of Pathology, New York University School of Medicine, New York, New York, United States
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136
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Cholesterol in the retina: the best is yet to come. Prog Retin Eye Res 2014; 41:64-89. [PMID: 24704580 DOI: 10.1016/j.preteyeres.2014.03.002] [Citation(s) in RCA: 192] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/13/2014] [Accepted: 03/17/2014] [Indexed: 01/09/2023]
Abstract
Historically understudied, cholesterol in the retina is receiving more attention now because of genetic studies showing that several cholesterol-related genes are risk factors for age-related macular degeneration (AMD) and because of eye pathology studies showing high cholesterol content of drusen, aging Bruch's membrane, and newly found subretinal lesions. The challenge before us is determining how the cholesterol-AMD link is realized. Meeting this challenge will require an excellent understanding these genes' roles in retinal physiology and how chorioretinal cholesterol is maintained. In the first half of this review, we will succinctly summarize physico-chemical properties of cholesterol, its distribution in the human body, general principles of maintenance and metabolism, and differences in cholesterol handling in human and mouse that impact on experimental approaches. This information will provide a backdrop to the second part of the review focusing on unique aspects of chorioretinal cholesterol homeostasis, aging in Bruch's membrane, cholesterol in AMD lesions, a model for lesion biogenesis, a model for macular vulnerability based on vascular biology, and alignment of AMD-related genes and pathobiology using cholesterol and an atherosclerosis-like progression as unifying features. We conclude with recommendations for the most important research steps we can take towards delineating the cholesterol-AMD link.
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137
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Li Y, Liu X, Zhou T, Kelley MR, Edwards P, Gao H, Qiao X. Inhibition of APE1/Ref-1 redox activity rescues human retinal pigment epithelial cells from oxidative stress and reduces choroidal neovascularization. Redox Biol 2014; 2:485-94. [PMID: 24624338 PMCID: PMC3949093 DOI: 10.1016/j.redox.2014.01.023] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 01/29/2014] [Accepted: 01/31/2014] [Indexed: 02/06/2023] Open
Abstract
The effectiveness of current treatment for age related macular degeneration (AMD) by targeting one molecule is limited due to its multifactorial nature and heterogeneous pathologies. Treatment strategy to target multiple signaling pathways or pathological components in AMD pathogenesis is under investigation for better clinical outcome. Inhibition of the redox function of apurinic endonuclease 1/redox factor-1 (APE1) was found to suppress endothelial angiogenesis and promote neuronal cell recovery, thereby may serve as a potential treatment for AMD. In the current study, we for the first time have found that a specific inhibitor of APE1 redox function by a small molecule compound E3330 regulates retinal pigment epithelium (RPEs) cell response to oxidative stress. E3330 significantly blocked sub-lethal doses of oxidized low density lipoprotein (oxLDL) induced proliferation decline and senescence advancement of RPEs. At the same time, E3330 remarkably decreased the accumulation of intracellular reactive oxygen species (ROS) and down-regulated the productions of monocyte chemoattractant protein-1 (MCP-1) and vascular endothelial growth factor (VEGF), as well as attenuated the level of nuclear factor-κB (NF-κB) p65 in RPEs. A panel of stress and toxicity responsive transcription factors that were significantly upregulated by oxLDL was restored by E3330, including Nrf2/Nrf1, p53, NF-κB, HIF1, CBF/NF-Y/YY1, and MTF-1. Further, a single intravitreal injection of E3330 effectively reduced the progression of laser-induced choroidal neovascularization (CNV) in mouse eyes. These data revealed that E3330 effectively rescued RPEs from oxidative stress induced senescence and dysfunctions in multiple aspects in vitro, and attenuated laser-induced damages to RPE–Bruch׳s membrane complex in vivo. Together with its previously established anti-angiogenic and neuroprotection benefits, E3330 is implicated for potential use for AMD treatment. Specific inhibition of APE1/Ref-1 redox function with E3330 blocked RPE proliferation decline and senescence-like phenotype advancement induced by oxLDL. E3330 suppressed intracellular ROS, down-regulated the MCP-1 and VEGF production, and reduced nuclear NF-κB p65 in RPEs. E3330 repressed the redox sensitive transcription factors Nrf2/Nrf1, p53, NF-κB, HIF1, CBF/NF-Y/YY1, and MTF-1 that stimulated by oxLDL in RPEs. Intravitreal injection of E3330 markedly reduced the laser-induced CNV in mouse eyes. E3330 holds great potential for the management of AMD.
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Key Words
- AMD, age related macular degeneration
- AP-1, activator protein 1
- APE1, apurinic endonuclease 1/redox factor-1
- APE1/Ref-1redox function
- Age-related macular degeneration.
- AhR, aryl hydrocarbon receptor
- ApoE, apolipoprotein E
- CBF/NF-Y/YY1, CCAAT binding factor/nuclear factor-Y/Yin Yang 1
- CECs, choroidal endothelial cells
- CNV, choroidal neovascularization
- DCFH-DA, dichlorodihydrofluorescin diacetate
- DMSO, dimethylsulphoxide
- E3330
- Fluc, firefly luciferase
- HIF-1α, hypoxia inducible factor-1α
- HSF1, heat-shock factor 1
- IκB-α, inhibitory NF-κB-α
- MCP-1, monocyte chemoattractant protein-1
- MTF1, metal regulatory transcription factor 1
- NF-κB, nuclear factor-κB
- Nox, NADPH oxidase
- Nrf, nuclear factor erythroid-2-related factor
- Oxidative stress
- RNV, retinal neovascularization
- ROS, reactive oxygen species
- RPE, retinal pigment epithelium
- RVECs, retinal vascular endothelial cells
- Retinal pigment epithelial cell
- Rluc, renilla luciferase
- SA-β-gal, senescence associated β-gal
- SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis
- TUNEL, TdT mediated dUTP-fluorescein nick end-labeling
- Transcription factor
- VEGF, vascular endothelial growth factor
- oxLDL, oxidized low density lipoprotein
- redox, reduction/oxidation
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Affiliation(s)
- Y Li
- Department of Ophthalmology, Henry Ford Health System, 1 Ford Place 5D, Detroit, MI, United States ; Department of Ophthalmology, Xijing Hospital, Fourth Military Medical University, Xi׳an, Shanxi, People׳s Republic of China
| | - X Liu
- Department of Ophthalmology, Henry Ford Health System, 1 Ford Place 5D, Detroit, MI, United States
| | - T Zhou
- Department of Ophthalmology, Henry Ford Health System, 1 Ford Place 5D, Detroit, MI, United States
| | - M R Kelley
- Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, United States
| | - P Edwards
- Department of Ophthalmology, Henry Ford Health System, 1 Ford Place 5D, Detroit, MI, United States
| | - H Gao
- Department of Ophthalmology, Henry Ford Health System, 1 Ford Place 5D, Detroit, MI, United States
| | - X Qiao
- Department of Ophthalmology, Henry Ford Health System, 1 Ford Place 5D, Detroit, MI, United States
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138
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Rudolf M, Seckerdieck K, Grisanti S, Curcio CA. Internal structure consistent with remodelling in very small drusen, revealed by filipin histochemistry for esterified cholesterol. Br J Ophthalmol 2014; 98:698-702. [DOI: 10.1136/bjophthalmol-2013-304226] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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139
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Radu RA, Hu J, Jiang Z, Bok D. Bisretinoid-mediated complement activation on retinal pigment epithelial cells is dependent on complement factor H haplotype. J Biol Chem 2014; 289:9113-20. [PMID: 24550392 DOI: 10.1074/jbc.m114.548669] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Age-related macular degeneration (AMD) is a common central blinding disease of the elderly. Homozygosity for a sequence variant causing Y402H and I62V substitutions in the gene for complement factor H (CFH) is strongly associated with risk of AMD. CFH, secreted by many cell types, including those of the retinal pigment epithelium (RPE), is a regulatory protein that inhibits complement activation. Recessive Stargardt maculopathy is another central blinding disease caused by mutations in the gene for ABCA4, a transporter in photoreceptor outer segments (OS) that clears retinaldehyde and prevents formation of toxic bisretinoids. Photoreceptors daily shed their distal OS, which are phagocytosed by the RPE cells. Here, we investigated the relationship between the CFH haplotype of human RPE (hRPE) cells, exposure to OS containing bisretinoids, and complement activation. We show that hRPE cells of the AMD-predisposing CFH haplotype (HH402/VV62) are attacked by complement following exposure to bisretinoid-containing Abca4(-/-) OS. This activation was dependent on factor B, indicating involvement of the alternative pathway. In contrast, hRPE cells of the AMD-protective CFH haplotype (YY402/II62) showed no complement activation following exposure to either Abca4(-/-) or wild-type OS. The AMD-protective YY402/II62 hRPE cells were more resistant to the membrane attack complex, whereas HH402/VV62 hRPE cells showed significant membrane attack complex deposition following ingestion of Abca4(-/-) OS. These results suggest that bisretinoid accumulation in hRPE cells stimulates activation and dysregulation of complement. Cells with an intact complement negative regulatory system are protected from complement attack, whereas cells with reduced CFH synthesis because of the Y402H and I62V substitutions are vulnerable to disease.
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Affiliation(s)
- Roxana A Radu
- From the Stein Eye Institute, Department of Ophthalmology
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140
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Bowes Rickman C, Farsiu S, Toth CA, Klingeborn M. Dry age-related macular degeneration: mechanisms, therapeutic targets, and imaging. Invest Ophthalmol Vis Sci 2013; 54:ORSF68-80. [PMID: 24335072 DOI: 10.1167/iovs.13-12757] [Citation(s) in RCA: 184] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Age-related macular degeneration is the leading cause of irreversible visual dysfunction in individuals over 65 in Western Society. Patients with AMD are classified as having early stage disease (early AMD), in which visual function is affected, or late AMD (generally characterized as either "wet" neovascular AMD, "dry" atrophic AMD or both), in which central vision is severely compromised or lost. Until recently, there have been no therapies available to treat the disorder(s). Now, the most common wet form of late-stage AMD, choroidal neovascularization, generally responds to treatment with anti-vascular endothelial growth factor therapies. Nevertheless, there are no current therapies to restore lost vision in eyes with advanced atrophic AMD. Oral supplementation with the Age-Related Eye Disease Study (AREDS) or AREDS2 formulation (antioxidant vitamins C and E, lutein, zeaxanthin, and zinc) has been shown to reduce the risk of progression to advanced AMD, although the impact was in neovascular rather than atrophic AMD. Recent findings, however, have demonstrated several features of early AMD that are likely to be druggable targets for treatment. Studies have established that much of the genetic risk for AMD is associated with complement genes. Consequently, several complement-based therapeutic treatment approaches are being pursued. Potential treatment strategies against AMD deposit formation and protein and/or lipid deposition will be discussed, including anti-amyloid therapies. In addition, the role of autophagy in AMD and prevention of oxidative stress through modulation of the antioxidant system will be explored. Finally, the success of these new therapies in clinical trials and beyond relies on early detection, disease typing, and predicting disease progression, areas that are currently being rapidly transformed by improving imaging modalities and functional assays.
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141
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Mechanism of inflammation in age-related macular degeneration: an up-to-date on genetic landmarks. Mediators Inflamm 2013; 2013:435607. [PMID: 24369445 PMCID: PMC3863457 DOI: 10.1155/2013/435607] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 09/28/2013] [Indexed: 12/13/2022] Open
Abstract
Age-related macular degeneration (AMD) is the most common cause of irreversible visual impairment among people over 50 years of age, accounting for up to 50% of all cases of legal blindness in Western countries. Although the aging represents the main determinant of AMD, it must be considered a multifaceted disease caused by interactions among environmental risk factors and genetic backgrounds. Mounting evidence and/or arguments document the crucial role of inflammation and immune-mediated processes in the pathogenesis of AMD. Proinflammatory effects secondary to chronic inflammation (e.g., alternative complement activation) and heterogeneous types of oxidative stress (e.g., impaired cholesterol homeostasis) can result in degenerative damages at the level of crucial macular structures, that is photoreceptors, retinal pigment epithelium, and Bruch's membrane. In the most recent years, the association of AMD with genes, directly or indirectly, involved in immunoinflammatory pathways is increasingly becoming an essential core for AMD knowledge. Starting from the key basic-research notions detectable at the root of AMD pathogenesis, the present up-to-date paper reviews the best-known and/or the most attractive genetic findings linked to the mechanisms of inflammation of this complex disease.
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142
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Ardeljan D, Chan CC. Aging is not a disease: distinguishing age-related macular degeneration from aging. Prog Retin Eye Res 2013; 37:68-89. [PMID: 23933169 PMCID: PMC3830684 DOI: 10.1016/j.preteyeres.2013.07.003] [Citation(s) in RCA: 168] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 07/29/2013] [Accepted: 07/30/2013] [Indexed: 12/18/2022]
Abstract
Age-related macular degeneration (AMD) is a disease of the outer retina, characterized most significantly by atrophy of photoreceptors and retinal pigment epithelium accompanied with or without choroidal neovascularization. Development of AMD has been recognized as contingent on environmental and genetic risk factors, the strongest being advanced age. In this review, we highlight pathogenic changes that destabilize ocular homeostasis and promote AMD development. With normal aging, photoreceptors are steadily lost, Bruch's membrane thickens, the choroid thins, and hard drusen may form in the periphery. In AMD, many of these changes are exacerbated in addition to the development of disease-specific factors such as soft macular drusen. Para-inflammation, which can be thought of as an intermediate between basal and robust levels of inflammation, develops within the retina in an attempt to maintain ocular homeostasis, reflected by increased expression of the anti-inflammatory cytokine IL-10 coupled with shifts in macrophage plasticity from the pro-inflammatory M1 to the anti-inflammatory M2 polarization. In AMD, imbalances in the M1 and M2 populations together with activation of retinal microglia are observed and potentially contribute to tissue degeneration. Nonetheless, the retina persists in a state of chronic inflammation and increased expression of certain cytokines and inflammasomes is observed. Since not everyone develops AMD, the vital question to ask is how the body establishes a balance between normal age-related changes and the pathological phenotypes in AMD.
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Affiliation(s)
- Daniel Ardeljan
- Immunopathology Section, Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA; Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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143
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Aryl hydrocarbon receptor deficiency causes dysregulated cellular matrix metabolism and age-related macular degeneration-like pathology. Proc Natl Acad Sci U S A 2013; 110:E4069-78. [PMID: 24106308 DOI: 10.1073/pnas.1307574110] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The aryl hydrocarbon receptor (AhR) is a nuclear receptor that regulates xenobiotic metabolism and detoxification. Herein, we report a previously undescribed role for the AhR signaling pathway as an essential defense mechanism in the pathogenesis of early dry age-related macular degeneration (AMD), the leading cause of vision loss in the elderly. We found that AhR activity and protein levels in human retinal pigment epithelial (RPE) cells, cells vulnerable in AMD, decrease with age. This finding is significant given that age is the most established risk factor for development of AMD. Moreover, AhR(-/-) mice exhibit decreased visual function and develop dry AMD-like pathology, including disrupted RPE cell tight junctions, accumulation of RPE cell lipofuscin, basal laminar and linear-like deposit material, Bruch's membrane thickening, and progressive RPE and choroidal atrophy. High-serum low-density lipoprotein levels were also observed in AhR(-/-) mice. In its oxidized form, this lipoprotein can stimulate increased secretion of extracellular matrix molecules commonly found in deposits from RPE cells, in an AhR-dependent manner. This study demonstrates the importance of cellular clearance via the AhR signaling pathway in dry AMD pathogenesis, implicating AhR as a potential target, and the mouse model as a useful platform for validating future therapies.
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144
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Cao L, Liu C, Wang F, Wang H. SIRT1 negatively regulates amyloid-beta-induced inflammation via the NF-κB pathway. Braz J Med Biol Res 2013; 46:659-69. [PMID: 24036938 PMCID: PMC3854412 DOI: 10.1590/1414-431x20132903] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 05/28/2013] [Indexed: 02/02/2023] Open
Abstract
Chronic inflammation induced by amyloid-beta (Aβ) plays a key role in the development
of age-related macular degeneration (AMD), and matrix metalloproteinase-9 (MMP-9),
interleukin (IL)-6, and IL-8 may be associated with chronic inflammation in AMD.
Sirtuin 1 (SIRT1) regulates inflammation via inhibition of nuclear factor-kappa B
(NF-κB) signaling, and resveratrol has been reported to prevent Aβ-induced retinal
degeneration; therefore, we investigated whether this action was mediated via
activation of SIRT1 signaling. Human adult retinal pigment epithelial (RPE) cells
were exposed to Aβ, and overactivation and knockdown of SIRT1 were performed to
investigate whether SIRT1 is required for abrogating Aβ-induced inflammation. We
found that Aβ-induced RPE barrier disruption and expression of IL-6, IL-8, and MMP-9
were abrogated by the SIRT1 activator SRT1720, whereas alterations induced by Aβ in
SIRT1-silenced RPE cells were not attenuated by SRT1720. In addition, SRT1720
inhibited Aβ-mediated NF-κB activation and decrease of the NF-κB inhibitor, IκBα. Our
findings suggest a protective role for SIRT1 signaling in Aβ-dependent retinal
degeneration and inflammation in AMD.
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Affiliation(s)
- L Cao
- Tenth People's Hospital, School of Medicine, Affiliate of Tongji University, Department of Ophthalmology, Shanghai, China
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145
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Rabin DM, Rabin RL, Blenkinsop TA, Temple S, Stern JH. Chronic oxidative stress upregulates Drusen-related protein expression in adult human RPE stem cell-derived RPE cells: a novel culture model for dry AMD. Aging (Albany NY) 2013; 5:51-66. [PMID: 23257616 PMCID: PMC3616231 DOI: 10.18632/aging.100516] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE The goal of this study was to examine changes in the expression of transcripts and proteins associated with drusen in Age-related Macular Degeneration (AMD) after exposing human retinal pigment epithelium (hRPE) cells to chronic oxidative stress. METHODS Primary adult human RPE cells were isolated from cadaveric donor eyes. The subpopulation of RPE stem cells (RPESCs) was activated, expanded, and then differentiated into RPE progeny. Confluent cultures of RPESC-derived hRPE and ARPE-19 cells were exposed to a regimen of tert-butylhydroperoxide (TBHP) for 1-5 days. After treatment, gene expression was measured by quantitative PCR (qPCR), protein expression was assessed by immunocytochemistry and transepithelial resistance and cell toxicity were measured. RESULTS hRPE cells exposed to a regimen of TBHP for 5 days upregulate expression of several molecules identified in drusen, including molecular chaperones and pro-angiogenic factors. 5-day TBHP treatment was significantly more effective than 1-day treatment at eliciting these effects. The extent of hRPE response to 5-day treatment varied significantly between individual donors, nevertheless, 6 transcripts were reliably significantly upregulated. ARPE-19 cells treated with the same 5-day stress regime did not show the same pattern of response and did not upregulate this group of transcripts. CONCLUSIONS RPESC-derived hRPE cells change significantly when exposed to repeated oxidative stress conditions, upregulating expression of several drusen-related proteins and transcripts. This is consistent with the hypothesis that hRPE cells are competent to be a source of proteins found in drusen deposits. Our results suggest that donor-specific genetic and environmental factors influence the RPE stress response. ARPE-19 cells appear to be less representative of AMD-like changes than RPESC-derived hRPE. This adult stem cell-based system using chronic TBHP treatment of hRPE represents a novel in vitro model useful for the study of drusen formation and dry AMD pathophysiology.
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Affiliation(s)
- David M Rabin
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany NY 12208, USA
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146
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Abstract
Age-related macular degeneration (AMD) is a leading cause of blindness in aged individuals. Recent advances have highlighted the essential role of immune processes in the development, progression and treatment of AMD. In this Review we discuss recent discoveries related to the immunological aspects of AMD pathogenesis. We outline the diverse immune cell types, inflammatory activators and pathways that are involved. Finally, we discuss the future of inflammation-directed therapeutics to treat AMD in the growing aged population.
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147
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Gorham RD, Forest DL, Tamamis P, López de Victoria A, Kraszni M, Kieslich CA, Banna CD, Bellows-Peterson ML, Larive CK, Floudas CA, Archontis G, Johnson LV, Morikis D. Novel compstatin family peptides inhibit complement activation by drusen-like deposits in human retinal pigmented epithelial cell cultures. Exp Eye Res 2013; 116:96-108. [PMID: 23954241 DOI: 10.1016/j.exer.2013.07.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 07/06/2013] [Accepted: 07/20/2013] [Indexed: 11/19/2022]
Abstract
We have used a novel human retinal pigmented epithelial (RPE) cell-based model that mimics drusen biogenesis and the pathobiology of age-related macular degeneration to evaluate the efficacy of newly designed peptide inhibitors of the complement system. The peptides belong to the compstatin family and, compared to existing compstatin analogs, have been optimized to promote binding to their target, complement protein C3, and to enhance solubility by improving their polarity/hydrophobicity ratios. Based on analysis of molecular dynamics simulation data of peptide-C3 complexes, novel binding features were designed by introducing intermolecular salt bridge-forming arginines at the N-terminus and at position -1 of N-terminal dipeptide extensions. Our study demonstrates that the RPE cell assay has discriminatory capability for measuring the efficacy and potency of inhibitory peptides in a macular disease environment.
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Affiliation(s)
- Ronald D Gorham
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
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148
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Garland DL, Fernandez-Godino R, Kaur I, Speicher KD, Harnly JM, Lambris JD, Speicher DW, Pierce EA. Mouse genetics and proteomic analyses demonstrate a critical role for complement in a model of DHRD/ML, an inherited macular degeneration. Hum Mol Genet 2013; 23:52-68. [PMID: 23943789 DOI: 10.1093/hmg/ddt395] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Macular degenerations, inherited and age related, are important causes of vision loss. Human genetic studies have suggested perturbation of the complement system is important in the pathogenesis of age-related macular degeneration. The mechanisms underlying the involvement of the complement system are not understood, although complement and inflammation have been implicated in drusen formation. Drusen are an early clinical hallmark of inherited and age-related forms of macular degeneration. We studied one of the earliest stages of macular degeneration which precedes and leads to the formation of drusen, i.e. the formation of basal deposits. The studies were done using a mouse model of the inherited macular dystrophy Doyne Honeycomb Retinal Dystrophy/Malattia Leventinese (DHRD/ML) which is caused by a p.Arg345Trp mutation in EFEMP1. The hallmark of DHRD/ML is the formation of drusen at an early age, and gene targeted Efemp1(R345W/R345W) mice develop extensive basal deposits. Proteomic analyses of Bruch's membrane/choroid and Bruch's membrane in the Efemp1(R345W/R345W) mice indicate that the basal deposits comprise normal extracellular matrix (ECM) components present in abnormal amounts. The proteomic analyses also identified significant changes in proteins with immune-related function, including complement components, in the diseased tissue samples. Genetic ablation of the complement response via generation of Efemp1(R345W/R345W):C3(-/-) double-mutant mice inhibited the formation of basal deposits. The results demonstrate a critical role for the complement system in basal deposit formation, and suggest that complement-mediated recognition of abnormal ECM may participate in basal deposit formation in DHRD/ML and perhaps other macular degenerations.
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149
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Feigl B, Hutmacher D. Eyes on 3D-current 3D biomimetic disease concept models and potential applications in age-related macular degeneration. Adv Healthc Mater 2013; 2:1056-62. [PMID: 24000403 DOI: 10.1002/adhm.201200445] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Three-dimensional cellular models that mimic disease are being increasingly investigated and have opened an exciting new research area into understanding pathomechanisms. The advantage of 3D in vitro disease models is that they allow systematic and in depth studies of physiological and pathophysiological processes with less costs and ethical concerns that have arisen with animal models. The purpose of the 30 approach is to allow crosstalk between cells and microenvironment, and with cues from the microenvironment,cells can assemble their niche similar to in vivo conditions. The use of 3D models for mimicking disease processes such as cancer, osteoarthritis etc., Is only emerging and allows multidisciplinary teams consisting of tissue engineers, biologist biomaterial scientists and clinicians to work closely together. While in vitro systems require rigorous testing before they can be considered as replicates of the in vivo model, major steps have been made,suggesting that they will become powerful tools for studying physiological and pathophysiological processes. This paper aims to summarize some of the existing 3D models and proposes a novel 3D model of the eye structures that are involved in the most common cause of blindness in the Western World,namely age-related macular degeneration (AMD).
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150
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CAO LINING, WANG HAO, WANG FANG. Amyloid-β-induced matrix metalloproteinase-9 secretion is associated with retinal pigment epithelial barrier disruption. Int J Mol Med 2013; 31:1105-12. [DOI: 10.3892/ijmm.2013.1310] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Accepted: 02/12/2013] [Indexed: 11/06/2022] Open
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