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Defective phagosome motility and degradation in cell nonautonomous RPE pathogenesis of a dominant macular degeneration. Proc Natl Acad Sci U S A 2018; 115:5468-5473. [PMID: 29735674 DOI: 10.1073/pnas.1709211115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Stargardt macular dystrophy 3 (STGD3) is caused by dominant mutations in the ELOVL4 gene. Like other macular degenerations, pathogenesis within the retinal pigment epithelium (RPE) appears to contribute to the loss of photoreceptors from the central retina. However, the RPE does not express ELOVL4, suggesting photoreceptor cell loss in STGD3 occurs through two cell nonautonomous events: mutant photoreceptors first affect RPE cell pathogenesis, and then, second, RPE dysfunction leads to photoreceptor cell death. Here, we have investigated how the RPE pathology occurs, using a STGD3 mouse model in which mutant human ELOVL4 is expressed in the photoreceptors. We found that the mutant protein was aberrantly localized to the photoreceptor outer segment (POS), and that resulting POS phagosomes were degraded more slowly in the RPE. In cell culture, the mutant POSs are ingested by primary RPE cells normally, but the phagosomes are processed inefficiently, even by wild-type RPE. The mutant phagosomes excessively sequester RAB7A and dynein, and have impaired motility. We propose that the abnormal presence of ELOVL4 protein in POSs results in phagosomes that are defective in recruiting appropriate motor protein linkers, thus contributing to slower degradation because their altered motility results in slower basal migration and fewer productive encounters with endolysosomes. In the transgenic mouse retinas, the RPE accumulated abnormal-looking phagosomes and oxidative stress adducts; these pathological changes were followed by pathology in the neural retina. Our results indicate inefficient phagosome degradation as a key component of the first cell nonautonomous event underlying retinal degeneration due to mutant ELOVL4.
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Ma WX, Huang XG, Yang TK, Yao JY. Involvement of dysregulated coding and long non‑coding RNAs in the pathogenesis of strabismus. Mol Med Rep 2018; 17:7737-7745. [PMID: 29620205 PMCID: PMC5983965 DOI: 10.3892/mmr.2018.8832] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Accepted: 03/09/2018] [Indexed: 01/05/2023] Open
Abstract
Strabismus is a common ocular disorder in children and may result in exterior abnormalities and impaired visual functions. However, the detailed pathogenesis of strabismus unclear. The present study assessed the comprehensive analyses on the roles of RNAs in the development of strabismus. The public datasets of strabismus and the corresponding control tissues were downloaded from the Gene Expression Omnibus (GEO). Reannotations of the dysregulated coding and long non-coding RNAs (lncRNAs) and functional enrichments of the differently expressed genes (DEGs) were conducted. A total of 790 DEGs were screened (648 upregulated and 142 downregulated) in the present study. Among the DEGs, a total of 32 differently expressed lncRNAs were detected (14 upregulated and 18 downregulated). When the Gene Ontology (GO) enrichment was considered, it was identified that a total of 143 GO terms (82 for biological process, 31 for cellular component and 30 for molecular function) were identified. Among all the 57 detected Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, the phagosome pathway, which was labeled as hsa004145, demonstrated the most bioinformatics importance. However, most lncRNAs, except LINC01279 and LOC643733, indicated <3 target mRNAs and were not suitable for advanced bioinformatics analyses. Bioinformatics analyses demonstrated that there was a GO term for each lncRNA (proteinaceous extracellular for LINC01279 and cell surface for LOC643733). In conclusion, a set of coding RNA as well as lncRNAs differentially expressed in strabismus EOM samples were indicated. Notably, the present findings important information for advanced pathogenesis research and biomarkers detection.
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Affiliation(s)
- Wen-Xiu Ma
- Department of Ophthalmology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215000, P.R. China
| | - Xiao-Gang Huang
- Department of Ophthalmology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215000, P.R. China
| | - Tian-Ke Yang
- Department of Ophthalmology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215000, P.R. China
| | - Jing-Yan Yao
- Department of Ophthalmology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215000, P.R. China
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Keeling E, Lotery AJ, Tumbarello DA, Ratnayaka JA. Impaired Cargo Clearance in the Retinal Pigment Epithelium (RPE) Underlies Irreversible Blinding Diseases. Cells 2018; 7:E16. [PMID: 29473871 PMCID: PMC5850104 DOI: 10.3390/cells7020016] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Revised: 02/20/2018] [Accepted: 02/22/2018] [Indexed: 01/09/2023] Open
Abstract
Chronic degeneration of the Retinal Pigment Epithelium (RPE) is a precursor to pathological changes in the outer retina. The RPE monolayer, which lies beneath the neuroretina, daily internalises and digests large volumes of spent photoreceptor outer segments. Impaired cargo handling and processing in the endocytic/phagosome and autophagy pathways lead to the accumulation of lipofuscin and pyridinium bis-retinoid A2E aggregates and chemically modified compounds such as malondialdehyde and 4-hydroxynonenal within RPE. These contribute to increased proteolytic and oxidative stress, resulting in irreversible damage to post-mitotic RPE cells and development of blinding conditions such as age-related macular degeneration, Stargardt disease and choroideremia. Here, we review how impaired cargo handling in the RPE results in their dysfunction, discuss new findings from our laboratory and consider how newly discovered roles for lysosomes and the autophagy pathway could provide insights into retinopathies. Studies of these dynamic, molecular events have also been spurred on by recent advances in optics and imaging technology. Mechanisms underpinning lysosomal impairment in other degenerative conditions including storage disorders, α-synuclein pathologies and Alzheimer's disease are also discussed. Collectively, these findings help transcend conventional understanding of these intracellular compartments as simple waste disposal bags to bring about a paradigm shift in the way lysosomes are perceived.
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Affiliation(s)
- Eloise Keeling
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK.
| | - Andrew J Lotery
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK.
- Eye Unit, University Hospital Southampton NHS Foundation Trust, Southampton SO16 6YD, UK.
| | - David A Tumbarello
- Biological Sciences, Faculty of Natural & Environmental Sciences, Life Science Building 85, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK.
| | - J Arjuna Ratnayaka
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK.
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Cuenca N, Ortuño-Lizarán I, Pinilla I. Cellular Characterization of OCT and Outer Retinal Bands Using Specific Immunohistochemistry Markers and Clinical Implications. Ophthalmology 2017; 125:407-422. [PMID: 29037595 DOI: 10.1016/j.ophtha.2017.09.016] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 08/16/2017] [Accepted: 09/14/2017] [Indexed: 02/01/2023] Open
Abstract
PURPOSE OCT has been a technological breakthrough in the diagnosis, treatment, and follow-up of many ocular diseases, especially retinal and neuro-ophthalmologic pathologic conditions. Until now, several controversies have arisen over the specific cell types that the bands observed in the OCT represent, especially over the 4 outer retinal bands. DESIGN To correlate the 4 outer hyperreflective bands observed in the OCT with the histologic structures using human retinal sections and immunocytochemistry at the fovea level. PARTICIPANTS Eyes from human donors. METHODS Vertical cryosections of human retinas were immunostained with antibodies specific for cones photoreceptors, bipolar cells, mitochondria, Müller cells, and retinal pigment epithelium (RPE) cells and were visualized using confocal microscopy. MAIN OUTCOME MEASURES Morphological correlation between histology and OCT at the fovea level. RESULTS Triple immunolabeling allowed distinguishing between cells types and different cell compartments. Immunostaining with guanine nucleotide-binding protein β 3 (GNB3) and cellular retinaldehyde-binding protein (CRALBP) antibodies showed all retinal layers at the foveola, especially the separation between the outer nuclear layer and the Henle fiber layer. CRALBP and cytochrome C (Cyt C) immunolabeling revealed that hyperreflective bands 1 and 2, observed in the OCT, correspond to the outer limiting membrane and the cone ellipsoids, respectively, separated by the cone myoids. CRALBP, cytochrome C, and GNB3 showed that the RPE interdigitations extend along the entire external segment of the cones, we do not believe them to be the structure responsible for forming the third band. However, the identification of small fragments of cone outer segments within the RPE led us to characterize the third band as the cone phagosomes located in the top of the RPE. Finally, we propose that the fourth band corresponds to the accumulation of mitochondria at the basal portion of the RPE, as identified by cytochrome C immunoreactivity, and that the hyporeflective band between bands 3 and 4 corresponds to the RPE nuclei and melanosomes zone. CONCLUSIONS This study proposes a new interpretation of the outer retinal bands that leads to a more accurate interpretation of OCT images, providing information about the health of cones and their relationship with the RPE, and could help to form a better understanding of retinal disease diagnosis and prognosis.
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Affiliation(s)
- Nicolás Cuenca
- Department of Physiology, Genetics and Microbiology, Alicante University, Alicante, Spain; Alicante Institute for Health and Biomedical Research (ISABIAL-FISABIO Foundation), Alicante, Spain; Multidisciplinary Institute for Environmental Studies "Ramón Margalef," University of Alicante, Alicante, Spain.
| | - Isabel Ortuño-Lizarán
- Department of Physiology, Genetics and Microbiology, Alicante University, Alicante, Spain
| | - Isabel Pinilla
- Department of Ophthalmology, Lozano Blesa University Hospital, Zaragoza, Spain; Aragon Health Science Institute, Aragon, Spain
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55
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Rudolf M, Mir Mohi Sefat A, Miura Y, Tura A, Raasch W, Ranjbar M, Grisanti S, Aherrahrou Z, Wagner A, Messinger JD, Garber DW, Anantharamaiah GM, Curcio CA. ApoA-I Mimetic Peptide 4F Reduces Age-Related Lipid Deposition in Murine Bruch's Membrane and Causes Its Structural Remodeling. Curr Eye Res 2017; 43:135-146. [PMID: 28972410 DOI: 10.1080/02713683.2017.1370118] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PURPOSE Accumulation of lipoprotein-derived lipids including esterified and unesterified cholesterol in Bruch's membrane of human eyes is a major age-related change involved in initiating and sustaining soft drusen in age-related macular degeneration (AMD). The apolipoprotein (apo) A-I mimetic peptide 4F is a small anti-inflammatory and anti-atherogenic agent, and potent modifier of plasma membranes. We evaluated the effect of intravitreally-injected 4F on murine Bruch's membrane. METHODS We tested single intravitreal injections of 4F doses (0.6 µg, 1.2 µg, 2.4 µg, and placebo scrambled peptide) in ApoEnull mice ≥10 months of age. After 30 days, mice were euthanized. Eyes were processed for either direct immunofluorescence detection of esterified cholesterol (EC) in Bruch's membrane whole mounts via a perfringolysin O-based marker linked to green fluorescent protein or by transmission electron microscopic visualization of Bruch's membrane integrity. Fluorescein isothiocyanate-conjugated 4F was traced after injection. RESULTS All injected eyes showed a dose-dependent reduction of Bruch's membrane EC with a concomitant ultrastructural improvement compared to placebo treated eyes. At a 2.4 µg dose of 4F, EC was reduced on average by ~60% and Bruch's membrane returned to a regular pentalaminar structure and thickness. Tracer studies confirmed that injected 4F reached intraocular targets. CONCLUSION We demonstrated a highly effective pharmacological reduction of EC and restoration of Bruch's membrane ultrastructure. The apoA-I mimetic peptide 4F is a novel way to treat a critical AMD disease process and thus represents a new candidate for treating the underlying cause of AMD.
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Affiliation(s)
- Martin Rudolf
- a Department of Ophthalmology , University of Lübeck , Lübeck , Germany
| | | | - Yoko Miura
- a Department of Ophthalmology , University of Lübeck , Lübeck , Germany
| | - Aysegül Tura
- a Department of Ophthalmology , University of Lübeck , Lübeck , Germany
| | - Walter Raasch
- b Department of Experimental and Clinical Pharmacology and Toxicology , University of Lübeck , Lübeck , Germany
| | - Mahdy Ranjbar
- a Department of Ophthalmology , University of Lübeck , Lübeck , Germany.,c Laboratory for Angiogenesis & Ocular Cell Transplantation , University of Lübeck , Lübeck , Germany
| | | | - Zouhair Aherrahrou
- d Institute of Integrative and Experimental Genomics , University of Lübeck , Lübeck , Germany
| | - Anna Wagner
- a Department of Ophthalmology , University of Lübeck , Lübeck , Germany
| | - Jeffrey D Messinger
- e Department of Ophthalmology , University of Alabama at Birmingham , Birmingham , AL , USA
| | - David W Garber
- f Atherosclerosis Research Unit , University of Alabama at Birmingham , Birmingham , AL , USA
| | - G M Anantharamaiah
- f Atherosclerosis Research Unit , University of Alabama at Birmingham , Birmingham , AL , USA.,g Department of Medicine, Biochemistry and Molecular Genetics , University of Alabama at Birmingham , Birmingham , AL , USA
| | - Christine A Curcio
- e Department of Ophthalmology , University of Alabama at Birmingham , Birmingham , AL , USA
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56
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Hazim RA, Karumbayaram S, Jiang M, Dimashkie A, Lopes VS, Li D, Burgess BL, Vijayaraj P, Alva-Ornelas JA, Zack JA, Kohn DB, Gomperts BN, Pyle AD, Lowry WE, Williams DS. Differentiation of RPE cells from integration-free iPS cells and their cell biological characterization. Stem Cell Res Ther 2017; 8:217. [PMID: 28969679 PMCID: PMC5625837 DOI: 10.1186/s13287-017-0652-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 08/16/2017] [Accepted: 08/29/2017] [Indexed: 01/18/2023] Open
Abstract
Background Dysfunction of the retinal pigment epithelium (RPE) is implicated in numerous forms of retinal degeneration. The readily accessible environment of the eye makes it particularly suitable for the transplantation of RPE cells, which can now be derived from autologous induced pluripotent stem cells (iPSCs), to treat retinal degeneration. For RPE transplantation to become feasible in the clinic, patient-specific somatic cells should be reprogrammed to iPSCs without the introduction of reprogramming genes into the genome of the host cell, and then subsequently differentiated into RPE cells that are well characterized for safety and functionality prior to transplantation. Methods We have reprogrammed human dermal fibroblasts to iPSCs using nonintegrating RNA, and differentiated the iPSCs toward an RPE fate (iPSC-RPE), under Good Manufacturing Practice (GMP)-compatible conditions. Results Using highly sensitive assays for cell polarity, structure, organelle trafficking, and function, we found that iPSC-RPE cells in culture exhibited key characteristics of native RPE. Importantly, we demonstrate for the first time with any stem cell-derived RPE cell that live cells are able to support dynamic organelle transport. This highly sensitive test is critical for RPE cells intended for transplantation, since defects in intracellular motility have been shown to promote RPE pathogenesis akin to that found in macular degeneration. To test their capabilities for in-vivo transplantation, we injected the iPSC-RPE cells into the subretinal space of a mouse model of retinal degeneration, and demonstrated that the transplanted cells are capable of rescuing lost RPE function. Conclusions This report documents the successful generation, under GMP-compatible conditions, of human iPSC-RPE cells that possess specific characteristics of healthy RPE. The report adds to a growing literature on the utility of human iPSC-RPE cells for cell culture investigations on pathogenicity and for therapeutic transplantation, by corroborating findings of others, and providing important new information on essential RPE cell biological properties. Electronic supplementary material The online version of this article (doi:10.1186/s13287-017-0652-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Roni A Hazim
- Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, 100 Stein Plaza, Los Angeles, CA, 90095, USA
| | - Saravanan Karumbayaram
- Department of Microbiology Immunology and Molecular Genetics, Los Angeles, CA, USA. .,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, Los Angeles, CA, USA. .,Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA.
| | - Mei Jiang
- Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, 100 Stein Plaza, Los Angeles, CA, 90095, USA
| | - Anupama Dimashkie
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, Los Angeles, CA, USA
| | - Vanda S Lopes
- Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, 100 Stein Plaza, Los Angeles, CA, 90095, USA
| | - Douran Li
- Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, 100 Stein Plaza, Los Angeles, CA, 90095, USA.,Department of Molecular Cell and Developmental Biology, Los Angeles, CA, USA
| | - Barry L Burgess
- Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, 100 Stein Plaza, Los Angeles, CA, 90095, USA
| | - Preethi Vijayaraj
- Department of Pediatrics, David Geffen School of Medicine, Los Angeles, CA, USA.,Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA
| | | | - Jerome A Zack
- Department of Microbiology Immunology and Molecular Genetics, Los Angeles, CA, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, Los Angeles, CA, USA.,Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA.,Department of Medicine, David Geffen School of Medicine, Los Angeles, CA, USA
| | - Donald B Kohn
- Department of Microbiology Immunology and Molecular Genetics, Los Angeles, CA, USA.,Department of Pediatrics, David Geffen School of Medicine, Los Angeles, CA, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, Los Angeles, CA, USA.,Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA
| | - Brigitte N Gomperts
- Department of Pediatrics, David Geffen School of Medicine, Los Angeles, CA, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, Los Angeles, CA, USA.,Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA
| | - April D Pyle
- Department of Microbiology Immunology and Molecular Genetics, Los Angeles, CA, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, Los Angeles, CA, USA.,Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA
| | - William E Lowry
- Department of Molecular Cell and Developmental Biology, Los Angeles, CA, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, Los Angeles, CA, USA.,Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA
| | - David S Williams
- Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, 100 Stein Plaza, Los Angeles, CA, 90095, USA. .,Department of Neurobiology, David Geffen School of Medicine, Los Angeles, CA, USA. .,Molecular Biology Institute, Los Angeles, CA, USA. .,Brain Research Institute, University of California, Los Angeles, CA, USA.
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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: 69] [Impact Index Per Article: 9.9] [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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58
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Stanton JB, Marmorstein AD, Zhang Y, Marmorstein LY. Deletion of Efemp1 Is Protective Against the Development of Sub-RPE Deposits in Mouse Eyes. Invest Ophthalmol Vis Sci 2017; 58:1455-1461. [PMID: 28264101 PMCID: PMC5361459 DOI: 10.1167/iovs.16-20955] [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: 01/10/2023] Open
Abstract
Purpose EFEMP1 (fibulin-3) is mutated in Malattia Leventinese/Doyne's honeycomb retinal dystrophy (ML/DHRD), an inherited macular dystrophy similar to AMD. Both ML/DHRD and AMD are characterized by the presence of sub-RPE deposits. Efemp1 knockout mice do not develop sub-RPE deposits. This study was to test whether sub-RPE deposits can be induced in Efemp1 knockout mice by experimentally applied stress conditions that cause wild-type mice to develop sub-RPE deposits. Methods Efemp1 knockout and control mice at 6, 18, or 24 months old were fed with a synthetic high-fat diet (HFD). Beginning 1 month after starting the HFD, one group of mice was exposed to cigarette smoke daily for 1 month, and another group of mice was subjected to photochemical injury every other day for 2 weeks from a 488-nm argon laser. After the treatments, histologic analysis was performed to assess whether sub-RPE deposits were induced. Results Basal laminar deposits (BLamDs), a form of sub-RPE deposits, were observed in the 18- and 24-month-old wild-type mice but not in Efemp1 knockout mice in any age groups after exposure to HFD and cigarette smoke or laser injury. Conclusions Mice lacking fibulin-3 do not develop sub-RPE deposits. Environmental oxidative stressors (HFD/cigarette smoke or HFD/laser) known to cause BLamD formation in wild-type mice failed to induce BLamD formation in Efemp1 knockout mice. These results suggest that fibulin-3 is a central player in the development of BLamD, and deletion of fibulin-3 is protective against the development of BLamD.
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Affiliation(s)
- 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
| | - Youwen Zhang
- 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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59
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Reyes-Reveles J, Dhingra A, Alexander D, Bragin A, Philp NJ, Boesze-Battaglia K. Phagocytosis-dependent ketogenesis in retinal pigment epithelium. J Biol Chem 2017; 292:8038-8047. [PMID: 28302729 DOI: 10.1074/jbc.m116.770784] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 03/13/2017] [Indexed: 11/06/2022] Open
Abstract
Daily, the retinal pigment epithelium (RPE) ingests a bolus of lipid and protein in the form of phagocytized photoreceptor outer segments (OS). The RPE, like the liver, expresses enzymes required for fatty acid oxidation and ketogenesis. This suggests that these pathways play a role in the disposal of lipids from ingested OS, as well as providing a mechanism for recycling metabolic intermediates back to the outer retina. In this study, we examined whether OS phagocytosis was linked to ketogenesis. We found increased levels of β-hydroxybutyrate (β-HB) in the apical medium following ingestion of OS by human fetal RPE and ARPE19 cells cultured on Transwell inserts. No increase in ketogenesis was observed following ingestion of oxidized OS or latex beads. Our studies further defined the connection between OS phagocytosis and ketogenesis in wild-type mice and mice with defects in phagosome maturation using a mouse RPE explant model. In explant studies, the levels of β-HB released were temporally correlated with OS phagocytic burst after light onset. In the Mreg-/- mouse where phagosome maturation is delayed, there was a temporal shift in the release of β-HB. An even more pronounced shift in maximal β-HB production was observed in the Abca4-/- RPE, in which loss of the ATP-binding cassette A4 transporter results in defective phagosome processing and accumulation of lipid debris. These studies suggest that FAO and ketogenesis are key to supporting the metabolism of the RPE and preventing the accumulation of lipids that lead to oxidative stress and mitochondrial dysfunction.
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Affiliation(s)
- Juan Reyes-Reveles
- From the Department of Biochemistry, School of Dental Medicine (SDM), University of Pennsylvania, Philadelphia, Pennsylvania 19104 and
| | - Anuradha Dhingra
- From the Department of Biochemistry, School of Dental Medicine (SDM), University of Pennsylvania, Philadelphia, Pennsylvania 19104 and
| | - Desiree Alexander
- From the Department of Biochemistry, School of Dental Medicine (SDM), University of Pennsylvania, Philadelphia, Pennsylvania 19104 and
| | - Alvina Bragin
- From the Department of Biochemistry, School of Dental Medicine (SDM), University of Pennsylvania, Philadelphia, Pennsylvania 19104 and
| | - Nancy J Philp
- the Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19146
| | - Kathleen Boesze-Battaglia
- From the Department of Biochemistry, School of Dental Medicine (SDM), University of Pennsylvania, Philadelphia, Pennsylvania 19104 and
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60
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Protective responses to sublytic complement in the retinal pigment epithelium. Proc Natl Acad Sci U S A 2016; 113:8789-94. [PMID: 27432952 DOI: 10.1073/pnas.1523061113] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The retinal pigment epithelium (RPE) is a key site of injury in inherited and age-related macular degenerations. Abnormal activation of the complement system is a feature of these blinding diseases, yet how the RPE combats complement attack is poorly understood. The complement cascade terminates in the cell-surface assembly of membrane attack complexes (MACs), which promote inflammation by causing aberrant signal transduction. Here, we investigated mechanisms crucial for limiting MAC assembly and preserving cellular integrity in the RPE and asked how these are compromised in models of macular degeneration. Using polarized primary RPE and the pigmented Abca4(-/-) Stargardt disease mouse model, we provide evidence for two protective responses occurring within minutes of complement attack, which are essential for maintaining mitochondrial health in the RPE. First, accelerated recycling of the membrane-bound complement regulator CD59 to the RPE cell surface inhibits MAC formation. Second, fusion of lysosomes with the RPE plasma membrane immediately after complement attack limits sustained elevations in intracellular calcium and prevents mitochondrial injury. Cholesterol accumulation in the RPE, induced by vitamin A dimers or oxidized LDL, inhibits these defense mechanisms by activating acid sphingomyelinase (ASMase), which increases tubulin acetylation and derails organelle traffic. Defective CD59 recycling and lysosome exocytosis after complement attack lead to mitochondrial fragmentation and oxidative stress in the RPE. Drugs that stimulate cholesterol efflux or inhibit ASMase restore both these critical safeguards in the RPE and avert complement-induced mitochondrial injury in vitro and in Abca4(-/-) mice, indicating that they could be effective therapeutic approaches for macular degenerations.
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Lambert NG, ElShelmani H, Singh MK, Mansergh FC, Wride MA, Padilla M, Keegan D, Hogg RE, Ambati BK. Risk factors and biomarkers of age-related macular degeneration. Prog Retin Eye Res 2016; 54:64-102. [PMID: 27156982 DOI: 10.1016/j.preteyeres.2016.04.003] [Citation(s) in RCA: 225] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 04/01/2016] [Accepted: 04/12/2016] [Indexed: 02/03/2023]
Abstract
A biomarker can be a substance or structure measured in body parts, fluids or products that can affect or predict disease incidence. As age-related macular degeneration (AMD) is the leading cause of blindness in the developed world, much research and effort has been invested in the identification of different biomarkers to predict disease incidence, identify at risk individuals, elucidate causative pathophysiological etiologies, guide screening, monitoring and treatment parameters, and predict disease outcomes. To date, a host of genetic, environmental, proteomic, and cellular targets have been identified as both risk factors and potential biomarkers for AMD. Despite this, their use has been confined to research settings and has not yet crossed into the clinical arena. A greater understanding of these factors and their use as potential biomarkers for AMD can guide future research and clinical practice. This article will discuss known risk factors and novel, potential biomarkers of AMD in addition to their application in both academic and clinical settings.
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Affiliation(s)
- Nathan G Lambert
- Ambati Lab, John A. Moran Eye Center, 65 Mario Capecchi Drive, Salt Lake City, UT, USA; Department of Ophthalmology & Visual Sciences, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT, USA.
| | - Hanan ElShelmani
- Ocular Development and Neurobiology Research Group, Zoology Department, School of Natural Sciences, University of Dublin, Trinity College, Dublin 2, Ireland.
| | - Malkit K Singh
- Ambati Lab, John A. Moran Eye Center, 65 Mario Capecchi Drive, Salt Lake City, UT, USA; Department of Ophthalmology & Visual Sciences, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT, USA.
| | - Fiona C Mansergh
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, Ireland.
| | - Michael A Wride
- Ocular Development and Neurobiology Research Group, Zoology Department, School of Natural Sciences, University of Dublin, Trinity College, Dublin 2, Ireland.
| | - Maximilian Padilla
- Ambati Lab, John A. Moran Eye Center, 65 Mario Capecchi Drive, Salt Lake City, UT, USA; Department of Ophthalmology & Visual Sciences, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT, USA.
| | - David Keegan
- Mater Misericordia Hospital, Eccles St, Dublin 7, Ireland.
| | - Ruth E Hogg
- Centre for Experimental Medicine, Institute of Clinical Science Block A, Grosvenor Road, Belfast, Co.Antrim, Northern Ireland, UK.
| | - Balamurali K Ambati
- Ambati Lab, John A. Moran Eye Center, 65 Mario Capecchi Drive, Salt Lake City, UT, USA; Department of Ophthalmology & Visual Sciences, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT, USA.
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