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Rzhanova LA, Markitantova YV, Aleksandrova MA. Recent Achievements in the Heterogeneity of Mammalian and Human Retinal Pigment Epithelium: In Search of a Stem Cell. Cells 2024; 13:281. [PMID: 38334673 PMCID: PMC10854871 DOI: 10.3390/cells13030281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 01/23/2024] [Accepted: 02/01/2024] [Indexed: 02/10/2024] Open
Abstract
Retinal pigment epithelium (RPE) cells are important fundamentally for the development and function of the retina. In this regard, the study of the morphological and molecular properties of RPE cells, as well as their regenerative capabilities, is of particular importance for biomedicine. However, these studies are complicated by the fact that, despite the external morphological similarity of RPE cells, the RPE is a population of heterogeneous cells, the molecular genetic properties of which have begun to be revealed by sequencing methods only in recent years. This review carries out an analysis of the data from morphological and molecular genetic studies of the heterogeneity of RPE cells in mammals and humans, which reveals the individual differences in the subpopulations of RPE cells and the possible specificity of their functions. Particular attention is paid to discussing the properties of "stemness," proliferation, and plasticity in the RPE, which may be useful for uncovering the mechanisms of retinal diseases associated with pathologies of the RPE and finding new ways of treating them.
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Affiliation(s)
| | - Yuliya V. Markitantova
- Koltzov Institute of Developmental Biology of the Russian Academy of Sciences, 26 Vavilov Street, 119334 Moscow, Russia; (L.A.R.); (M.A.A.)
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2
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Mullin NK, Voigt AP, Boese EA, Liu X, Stone EM, Tucker BA, Mullins RF. Transcriptomic and Chromatin Accessibility Analysis of the Human Macular and Peripheral Retinal Pigment Epithelium at the Single-Cell Level. THE AMERICAN JOURNAL OF PATHOLOGY 2023; 193:1750-1761. [PMID: 36775060 PMCID: PMC10616710 DOI: 10.1016/j.ajpath.2023.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/12/2023] [Accepted: 01/26/2023] [Indexed: 02/12/2023]
Abstract
Some human retinal diseases are characterized by pathology that is restricted to specific cell types and to specific regions of the eye. Several disease entities either selectively affect or spare the macula, the retina region at the center of the posterior pole. Photoreceptor cells in the macula are involved in high-acuity vision and require metabolic support from non-neuronal cell types. Some macular diseases involve the retinal pigment epithelium (RPE), an epithelial cell layer with several metabolic-support functions essential for the overlying photoreceptors. In the current study, the ways in which RPE confers region-specific disease susceptibility were determined by examining heterogeneity within RPE tissue from human donors. RPE nuclei from the macular and peripheral retina were profiled using joint single-nucleus RNA and ATAC sequencing. The expression of several genes differed between macular and peripheral RPE. Region-specific ATAC peaks were found, suggesting regulatory elements used exclusively by macular or peripheral RPE. Across anatomic regions, subpopulations of RPE were identified that appeared to have differential levels of expression of visual cycle genes. Finally, loci associated with age-related macular degeneration were examined for a better understanding of RPE-specific disease phenotypes. These findings showed variations in the regulation of gene expression in the human RPE by region and subpopulation, and provide a source for a better understanding of the molecular basis of macular disease.
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Affiliation(s)
- Nathaniel K Mullin
- Institute for Vision Research, University of Iowa, Iowa City, Iowa; Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa; Medical Scientist Training Program, University of Iowa, Iowa City, Iowa
| | - Andrew P Voigt
- Institute for Vision Research, University of Iowa, Iowa City, Iowa; Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa; Medical Scientist Training Program, University of Iowa, Iowa City, Iowa
| | - Erin A Boese
- Institute for Vision Research, University of Iowa, Iowa City, Iowa; Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa
| | - Xiuying Liu
- Institute for Vision Research, University of Iowa, Iowa City, Iowa; Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa
| | - Edwin M Stone
- Institute for Vision Research, University of Iowa, Iowa City, Iowa; Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa
| | - Budd A Tucker
- Institute for Vision Research, University of Iowa, Iowa City, Iowa; Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa
| | - Robert F Mullins
- Institute for Vision Research, University of Iowa, Iowa City, Iowa; Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa.
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3
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Malek G. Location of Retinal Pigment Epithelial Cells in the Eye Is Critical to Their Function. THE AMERICAN JOURNAL OF PATHOLOGY 2023; 193:1691-1693. [PMID: 37160188 PMCID: PMC10616708 DOI: 10.1016/j.ajpath.2023.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 04/19/2023] [Accepted: 04/25/2023] [Indexed: 05/11/2023]
Affiliation(s)
- Goldis Malek
- Department of Ophthalmology, Duke Eye Center, Duke University School of Medicine, Durham, North Carolina; Department of Pathology, Duke University School of Medicine, Durham, North Carolina.
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4
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Mungale A, McGaughey DM, Zhang C, Yousaf S, Liu J, Brooks BP, Maminishkis A, Fufa TD, Hufnagel RB. Transcriptional mapping of the macaque retina and RPE-choroid reveals conserved inter-tissue transcription drivers and signaling pathways. Front Genet 2022; 13:949449. [PMID: 36506320 PMCID: PMC9732541 DOI: 10.3389/fgene.2022.949449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 11/01/2022] [Indexed: 11/27/2022] Open
Abstract
The macula and fovea comprise a highly sensitive visual detection tissue that is susceptible to common disease processes like age-related macular degeneration (AMD). Our understanding of the molecular determinants of high acuity vision remains unclear, as few model organisms possess a human-like fovea. We explore transcription factor networks and receptor-ligand interactions to elucidate tissue interactions in the macula and peripheral retina and concomitant changes in the underlying retinal pigment epithelium (RPE)/choroid. Poly-A selected, 100 bp paired-end RNA-sequencing (RNA-seq) was performed across the macular/foveal, perimacular, and temporal peripheral regions of the neural retina and RPE/choroid tissues of four adult Rhesus macaque eyes to characterize region- and tissue-specific gene expression. RNA-seq reads were mapped to both the macaque and human genomes for maximum alignment and analyzed for differential expression and Gene Ontology (GO) enrichment. Comparison of the neural retina and RPE/choroid tissues indicated distinct, contiguously changing gene expression profiles from fovea through perimacula to periphery. Top GO enrichment of differentially expressed genes in the RPE/choroid included cell junction organization and epithelial cell development. Expression of transcriptional regulators and various disease-associated genes show distinct location-specific preference and retina-RPE/choroid tissue-tissue interactions. Regional gene expression changes in the macaque retina and RPE/choroid is greater than that found in previously published transcriptome analysis of the human retina and RPE/choroid. Further, conservation of human macula-specific transcription factor profiles and gene expression in macaque tissues suggest a conservation of programs required for retina and RPE/choroid function and disease susceptibility.
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Affiliation(s)
- Ameera Mungale
- Medical Genetics and Ophthalmic Genomics Unit, National Eye Institute, National Institutes of Health, Bethesda, MD, United States
| | - David M. McGaughey
- Bioinformatics Group, National Eye Institute, National Institutes of Health, Bethesda, MD, United States
| | - Congxiao Zhang
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, MD, United States
| | - Sairah Yousaf
- Medical Genetics and Ophthalmic Genomics Unit, National Eye Institute, National Institutes of Health, Bethesda, MD, United States
| | - James Liu
- Medical Genetics and Ophthalmic Genomics Unit, National Eye Institute, National Institutes of Health, Bethesda, MD, United States
| | - Brian P. Brooks
- Pediatric, Developmental and Genetic Ophthalmology, National Eye Institute, National Institutes of Health, Bethesda, MD, United States
| | - Arvydas Maminishkis
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, MD, United States
| | - Temesgen D. Fufa
- Medical Genetics and Ophthalmic Genomics Unit, National Eye Institute, National Institutes of Health, Bethesda, MD, United States
| | - Robert B. Hufnagel
- Medical Genetics and Ophthalmic Genomics Unit, National Eye Institute, National Institutes of Health, Bethesda, MD, United States
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5
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Lehmann GL, Ginsberg M, Nolan DJ, Rodríguez C, Martínez-González J, Zeng S, Voigt AP, Mullins RF, Rafii S, Rodriguez-Boulan E, Benedicto I. Retinal Pigment Epithelium-Secreted VEGF-A Induces Alpha-2-Macroglobulin Expression in Endothelial Cells. Cells 2022; 11:2975. [PMID: 36230937 PMCID: PMC9564307 DOI: 10.3390/cells11192975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/21/2022] [Accepted: 09/22/2022] [Indexed: 12/05/2022] Open
Abstract
Alpha-2-macroglobulin (A2M) is a protease inhibitor that regulates extracellular matrix (ECM) stability and turnover. Here, we show that A2M is expressed by endothelial cells (ECs) from human eye choroid. We demonstrate that retinal pigment epithelium (RPE)-conditioned medium induces A2M expression specifically in ECs. Experiments using chemical inhibitors, blocking antibodies, and recombinant proteins revealed a key role of VEGF-A in RPE-mediated A2M induction in ECs. Furthermore, incubation of ECs with RPE-conditioned medium reduces matrix metalloproteinase-2 gelatinase activity of culture supernatants, which is partially restored after A2M knockdown in ECs. We propose that dysfunctional RPE or choroidal blood vessels, as observed in retinal diseases such as age-related macular degeneration, may disrupt the crosstalk mechanism we describe here leading to alterations in the homeostasis of choroidal ECM, Bruch's membrane and visual function.
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Affiliation(s)
- Guillermo L. Lehmann
- Margaret Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medicine, New York, NY 10065, USA
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591, USA
| | | | | | - Cristina Rodríguez
- Institut de Recerca Hospital de la Santa Creu i Sant Pau, 08041 Barcelona, Spain
- Institut d’Investigació Biomèdica Sant Pau (IIB SANT PAU), 08041 Barcelona, Spain
- CIBER de Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - José Martínez-González
- Institut d’Investigació Biomèdica Sant Pau (IIB SANT PAU), 08041 Barcelona, Spain
- CIBER de Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Instituto de Investigaciones Biomédicas de Barcelona-Consejo Superior de Investigaciones Científicas (IIBB-CSIC), 08036 Barcelona, Spain
| | - Shemin Zeng
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, IA 52246, USA
| | - Andrew P. Voigt
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, IA 52246, USA
| | - Robert F. Mullins
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, IA 52246, USA
| | - Shahin Rafii
- Ansary Stem Cell Institute, Department of Medicine, Division of Regenerative Medicine, Weill Cornell Medicine, New York, NY 10065, USA
| | - Enrique Rodriguez-Boulan
- Margaret Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medicine, New York, NY 10065, USA
| | - Ignacio Benedicto
- Margaret Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medicine, New York, NY 10065, USA
- Departamento de Inmunología, Oftalmología y ORL, Facultad de Medicina, Universidad Complutense de Madrid, 28040 Madrid, Spain
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), 28029 Madrid, Spain
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6
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Ortolan D, Sharma R, Volkov A, Maminishkis A, Hotaling NA, Huryn LA, Cukras C, Di Marco S, Bisti S, Bharti K. Single-cell-resolution map of human retinal pigment epithelium helps discover subpopulations with differential disease sensitivity. Proc Natl Acad Sci U S A 2022; 119:e2117553119. [PMID: 35522714 PMCID: PMC9171647 DOI: 10.1073/pnas.2117553119] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 03/25/2022] [Indexed: 12/31/2022] Open
Abstract
Regional phenotypic and functional differences in the retinal pigment epithelium (RPE) monolayer have been suggested to account for regional susceptibility in ocular diseases such as age-related macular degeneration (AMD), late-onset retinal degeneration (L-ORD), and choroideremia (CHM). However, a comprehensive description of human topographical RPE diversity is not yet available, thus limiting the understanding of regional RPE diversity and degenerative disease sensitivity in the eye. To develop a complete morphometric RPE map of the human eye, artificial intelligence–based software was trained to recognize, segment, and analyze RPE borders. Five statistically different, concentric RPE subpopulations (P1 to P5) were identified using cell area as a parameter, including a subpopulation (P4) with cell area comparable to that of macular cells in the far periphery of the eye. This work provides a complete reference map of human RPE subpopulations and their location in the eye. In addition, the analysis of cadaver non-AMD and AMD eyes and ultra-widefield fundus images of patients revealed differential vulnerability of the five RPE subpopulations to different retinal diseases.
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Affiliation(s)
- Davide Ortolan
- Ocular and Stem Cell Translational Research Section, National Eye Institute, NIH, Bethesda, MD 20892
| | - Ruchi Sharma
- Ocular and Stem Cell Translational Research Section, National Eye Institute, NIH, Bethesda, MD 20892
| | - Andrei Volkov
- Ocular and Stem Cell Translational Research Section, National Eye Institute, NIH, Bethesda, MD 20892
| | - Arvydas Maminishkis
- Ocular and Stem Cell Translational Research Section, National Eye Institute, NIH, Bethesda, MD 20892
| | - Nathan A. Hotaling
- Information Resources Technology Branch, National Center for Advancing Translational Sciences, NIH, Bethesda, MD 20892
| | - Laryssa A. Huryn
- Ophthalmic Clinical Genetics Section, National Eye Institute, NIH, Bethesda, MD 20892
| | - Catherine Cukras
- Unit on Clinical Investigation of Retinal Disease, National Eye Institute, NIH, Bethesda, MD 20892
| | - Stefano Di Marco
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genova, Italy
| | - Silvia Bisti
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genova, Italy
- Biostructures and Biosystems National Institute, 00136 Roma, Italy
| | - Kapil Bharti
- Ocular and Stem Cell Translational Research Section, National Eye Institute, NIH, Bethesda, MD 20892
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7
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Jin HL, Jeong KW. Transcriptome Analysis of Long-Term Exposure to Blue Light in Retinal Pigment Epithelial Cells. Biomol Ther (Seoul) 2022; 30:291-297. [PMID: 35074938 PMCID: PMC9047491 DOI: 10.4062/biomolther.2021.155] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 12/18/2021] [Accepted: 01/05/2022] [Indexed: 11/15/2022] Open
Abstract
Dry age-related macular degeneration (AMD) is a type of progressive blindness that is primarily due to dysfunction and the loss of retinal pigment epithelium (RPE). The accumulation of N-retinylidene-N-retinylethanolamine (A2E), a by-product of the visual cycle, causes RPE and photoreceptor degeneration that impairs vision. Genes associated with dry AMD have been identified using a blue light model of A2E accumulation in the retinal pigment epithelium and transcriptomic studies of retinal tissue from patients with AMD. However, dry macular degeneration progresses slowly, and current approaches cannot reveal changes in gene transcription according to stages of AMD progression. Thus, they are limited in terms of identifying genes responsible for pathogenesis. Here, we created a model of long-term exposure to identify temporally-dependent changes in gene expression induced in human retinal pigment epithelial cells (ARPE-19) exposed to blue light and a non-cytotoxic dose of A2E for 120 days. We identified stage-specific genes at 40, 100, and 120 days, respectively. The expression of genes corresponding to epithelial-mesenchymal transition (EMT) during the early stage, glycolysis and angiogenesis during the middle stage, and apoptosis and inflammation pathways during the late stage was significantly altered by A2E and blue light. Changes in the expression of genes at the late stages of the EMT were similar to those found in human eyes with late-stage AMD. Our results provide further insight into the pathogenesis of dry AMD induced by blue light and a novel model in vitro with which relevant genes can be identified in the future.
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Affiliation(s)
- Hong Lan Jin
- Key Laboratory of Natural Medicines of the Changbai Mountain, Ministry of Education, Molecular Medicine Research Center, Yanbian University, College of Pharmacy, Yanbian University, Yanji 133002, China
| | - Kwang Won Jeong
- Gachon Research Institute of Pharmaceutical Sciences, College of Pharmacy, Gachon University, Incheon 21936, Republic of Korea
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8
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Liu S, Miyaji M, Hosoya O, Matsuo T. Effect of NK-5962 on Gene Expression Profiling of Retina in a Rat Model of Retinitis Pigmentosa. Int J Mol Sci 2021; 22:ijms222413276. [PMID: 34948073 PMCID: PMC8703378 DOI: 10.3390/ijms222413276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 12/03/2021] [Accepted: 12/06/2021] [Indexed: 11/18/2022] Open
Abstract
Purpose: NK-5962 is a key component of photoelectric dye-coupled polyethylene film, designated Okayama University type-retinal prosthesis (OUReP™). Previously, we found that NK-5962 solution could reduce the number of apoptotic photoreceptors in the eyes of the Royal College of Surgeons (RCS) rats by intravitreal injection under a 12 h light/dark cycle. This study aimed to explore possible molecular mechanisms underlying the anti-apoptotic effect of NK-5962 in the retina of RCS rats. Methods: RCS rats received intravitreal injections of NK-5962 solution in the left eye at the age of 3 and 4 weeks, before the age of 5 weeks when the speed in the apoptotic degeneration of photoreceptors reaches its peak. The vehicle-treated right eyes served as controls. All rats were housed under a 12 h light/dark cycle, and the retinas were dissected out at the age of 5 weeks for RNA sequence (RNA-seq) analysis. For the functional annotation of differentially expressed genes (DEGs), the Metascape and DAVID databases were used. Results: In total, 55 up-regulated DEGs, and one down-regulated gene (LYVE1) were found to be common among samples treated with NK-5962. These DEGs were analyzed using Gene Ontology (GO) term enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG), and Reactome pathway analyses. We focused on the up-regulated DEGs that were enriched in extracellular matrix organization, extracellular exosome, and PI3K–Akt signaling pathways. These terms and pathways may relate to mechanisms to protect photoreceptor cells. Moreover, our analyses suggest that SERPINF1, which encodes pigment epithelium-derived factor (PEDF), is one of the key regulatory genes involved in the anti-apoptotic effect of NK-5962 in RCS rat retinas. Conclusions: Our findings suggest that photoelectric dye NK-5962 may delay apoptotic death of photoreceptor cells in RCS rats by up-regulating genes related to extracellular matrix organization, extracellular exosome, and PI3K–Akt signaling pathways. Overall, our RNA-seq and bioinformatics analyses provide insights in the transcriptome responses in the dystrophic RCS rat retinas that were induced by NK-5962 intravitreal injection and offer potential target genes for developing new therapeutic strategies for patients with retinitis pigmentosa.
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Affiliation(s)
- Shihui Liu
- Department of Ophthalmology, Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, Okayama City 700-8558, Japan;
| | - Mary Miyaji
- Department of Medical Neurobiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama City 700-8558, Japan; (M.M.); (O.H.)
| | - Osamu Hosoya
- Department of Medical Neurobiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama City 700-8558, Japan; (M.M.); (O.H.)
| | - Toshihiko Matsuo
- Department of Ophthalmology, Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, Okayama City 700-8558, Japan;
- Correspondence:
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9
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Brinks J, van Dijk EHC, Klaassen I, Schlingemann RO, Kielbasa SM, Emri E, Quax PHA, Bergen AA, Meijer OC, Boon CJF. Exploring the choroidal vascular labyrinth and its molecular and structural roles in health and disease. Prog Retin Eye Res 2021; 87:100994. [PMID: 34280556 DOI: 10.1016/j.preteyeres.2021.100994] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/04/2021] [Accepted: 07/07/2021] [Indexed: 12/14/2022]
Abstract
The choroid is a key player in maintaining ocular homeostasis and plays a role in a variety of chorioretinal diseases, many of which are poorly understood. Recent advances in the field of single-cell RNA sequencing have yielded valuable insights into the properties of choroidal endothelial cells (CECs). Here, we review the role of the choroid in various physiological and pathophysiological mechanisms, focusing on the role of CECs. We also discuss new insights regarding the phenotypic properties of CECs, CEC subpopulations, and the value of measuring transcriptomics in primary CEC cultures derived from post-mortem eyes. In addition, we discuss key phenotypic, structural, and functional differences that distinguish CECs from other endothelial cells such as retinal vascular endothelial cells. Understanding the specific clinical and molecular properties of the choroid will shed new light on the pathogenesis of the broad clinical range of chorioretinal diseases such as age-related macular degeneration, central serous chorioretinopathy and other diseases within the pachychoroid spectrum, uveitis, and diabetic choroidopathy. Although our knowledge is still relatively limited with respect to the clinical features and molecular pathways that underlie these chorioretinal diseases, we summarise new approaches and discuss future directions for gaining new insights into these sight-threatening diseases and highlight new therapeutic strategies such as pluripotent stem cell‒based technologies and gene therapy.
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Affiliation(s)
- J Brinks
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - E H C van Dijk
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - I Klaassen
- Ocular Angiogenesis Group, Departments of Ophthalmology and Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
| | - R O Schlingemann
- Ocular Angiogenesis Group, Departments of Ophthalmology and Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands; Department of Ophthalmology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands; Department of Ophthalmology, University of Lausanne, Jules Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
| | - S M Kielbasa
- Department of Medical Statistics and Bioinformatics, Leiden University Medical Center, Leiden, the Netherlands
| | - E Emri
- Department of Clinical Genetics, Section of Ophthalmogenetics, Amsterdam University Medical Centers, Amsterdam, the Netherlands
| | - P H A Quax
- Department of Vascular Surgery, Leiden University Medical Center, Leiden, the Netherlands; Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - A A Bergen
- Department of Clinical Genetics, Section of Ophthalmogenetics, Amsterdam University Medical Centers, Amsterdam, the Netherlands
| | - O C Meijer
- Department of Medicine, Division of Endocrinology and Metabolism, Leiden University Medical Center, Leiden, the Netherlands
| | - C J F Boon
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands; Department of Ophthalmology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands.
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10
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Zhu S, Ye L, Bennett S, Xu H, He D, Xu J. Molecular structure, gene expression and functional role of WFDC1 in angiogenesis and cancer. Cell Biochem Funct 2021; 39:588-595. [PMID: 33615507 DOI: 10.1002/cbf.3624] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 12/29/2020] [Accepted: 01/17/2021] [Indexed: 02/04/2023]
Abstract
Whey acidic proteins (WAP) perform a diverse range of important biological functions, including proteinase activity, calcium transport and bacterial growth. The WAP four-disulphide core domain protein 1 (WFDC1) gene (also called PS20), encodes the 20 kDa prostate stromal protein (ps20), which is a member of the WAP-type four-disulphide core domain family of proteins, and exhibits characteristics of serine protease inhibitors, such as elafin and secretory leukocyte protease inhibitor. Molecular structural analysis reveals that ps20 consists of four-disulphide bonds formed by eight cysteine residues located at the carboxyl terminus of the protein. Wfdc1-null mice were found to display no overt developmental phenotype, suggesting a dispensable role in organ growth and development. However, WFDC1 was able to mediate endothelial cell migration and pericyte stabilization, which are vital for the formation of functional vascular structures. WFDC1 was also found to be downregulated in cancers and exhibited a regulatory effect on cell proliferation. In addition, it was involved in the modulation of memory T cells during human immunodeficiency virus infection. Gaining a solid understanding of the mechanisms by which WFDC1 regulates tissue homeostasis and disease processes, in a tissue specific manner, will be an important move towards the development of WFDC1/ps20 as potential therapeutic targets.
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Affiliation(s)
- Sipin Zhu
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China.,Division of Regenerative Biology, School of Biomedical Sciences, University of Western Australia, Perth, Western Australia, Australia
| | - Lin Ye
- Department of Orthopaedic Surgery, The Fifth Affiliated Hospital of Wenzhou Medical University, Lishui Municipal Central Hospital, Lishui, China
| | - Samuel Bennett
- Division of Regenerative Biology, School of Biomedical Sciences, University of Western Australia, Perth, Western Australia, Australia
| | - Huazi Xu
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Dengwei He
- Department of Orthopaedic Surgery, The Fifth Affiliated Hospital of Wenzhou Medical University, Lishui Municipal Central Hospital, Lishui, China
| | - Jiake Xu
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China.,Division of Regenerative Biology, School of Biomedical Sciences, University of Western Australia, Perth, Western Australia, Australia
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11
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Single-cell RNA sequencing in vision research: Insights into human retinal health and disease. Prog Retin Eye Res 2020; 83:100934. [PMID: 33383180 DOI: 10.1016/j.preteyeres.2020.100934] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 11/27/2020] [Accepted: 12/01/2020] [Indexed: 01/03/2023]
Abstract
Gene expression provides valuable insight into cell function. As such, vision researchers have frequently employed gene expression studies to better understand retinal physiology and disease. With the advent of single-cell RNA sequencing, expression experiments provide an unparalleled resolution of information. Instead of studying aggregated gene expression across all cells in a heterogenous tissue, single-cell technology maps RNA to an individual cell, which facilitates grouping of retinal and choroidal cell types for further study. Single-cell RNA sequencing has been quickly adopted by both basic and translational vision researchers, and single-cell level gene expression has been studied in the visual systems of animal models, retinal organoids, and primary human retina, RPE, and choroid. These experiments have generated detailed atlases of gene expression and identified new retinal cell types. Likewise, single-cell RNA sequencing investigations have characterized how gene expression changes in the setting of many retinal diseases, including how choroidal endothelial cells are altered in age-related macular degeneration. In addition, this technology has allowed vision researchers to discover drivers of retinal development and model rare retinal diseases with induced pluripotent stem cells. In this review, we will overview the growing number of single-cell RNA sequencing studies in the field of vision research. We will summarize experimental considerations for designing single-cell RNA sequencing experiments and highlight important advancements in retinal, RPE, choroidal, and retinal organoid biology driven by this technology. Finally, we generalize these findings to genes involved in retinal degeneration and outline the future of single-cell expression experiments in studying retinal disease.
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Voigt AP, Whitmore SS, Lessing ND, DeLuca AP, Tucker BA, Stone EM, Mullins RF, Scheetz TE. Spectacle: An interactive resource for ocular single-cell RNA sequencing data analysis. Exp Eye Res 2020; 200:108204. [PMID: 32910939 DOI: 10.1016/j.exer.2020.108204] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/06/2020] [Accepted: 08/25/2020] [Indexed: 12/11/2022]
Abstract
Single-cell RNA sequencing has revolutionized ocular gene expression studies. This technology has enabled researchers to identify expression signatures for rare cell types and characterize how gene expression changes across biological conditions, such as topographic region or disease status. However, sharing single-cell RNA sequencing results remains a major obstacle, particular for individuals without a computational background. To address these limitations, we developed Spectacle, an interactive web-based resource for exploring previously published single-cell RNA sequencing data from ocular studies. Spectacle is powered by a locally developed R package, cellcuratoR, which utilizes the Shiny framework in R to generate interactive visualizations for single-cell expression data. Spectacle contains five pre-processed ocular single-cell RNA sequencing data sets and is accessible via the web at OcularGeneExpression.org/singlecell. With Spectacle, users can interactively identify which cell types express a gene of interest, detect transcriptomic subpopulations within a cell type, and perform highly flexible differential expression analyses. The freely-available Spectacle system reduces the bioinformatic barrier for interacting with rich single-cell RNA sequencing studies from ocular tissues, making it easy to quickly identify cell types that express a gene of interest.
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Affiliation(s)
- Andrew P Voigt
- Departments of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA; Institute for Vision Research, the University of Iowa, Iowa City, IA, 52242, USA
| | - S Scott Whitmore
- Departments of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA; Institute for Vision Research, the University of Iowa, Iowa City, IA, 52242, USA
| | - Nicholas D Lessing
- Departments of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA; Institute for Vision Research, the University of Iowa, Iowa City, IA, 52242, USA
| | - Adam P DeLuca
- Departments of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA; Institute for Vision Research, the University of Iowa, Iowa City, IA, 52242, USA
| | - Budd A Tucker
- Departments of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA; Institute for Vision Research, the University of Iowa, Iowa City, IA, 52242, USA
| | - Edwin M Stone
- Departments of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA; Institute for Vision Research, the University of Iowa, Iowa City, IA, 52242, USA
| | - Robert F Mullins
- Departments of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA; Institute for Vision Research, the University of Iowa, Iowa City, IA, 52242, USA
| | - Todd E Scheetz
- Departments of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA; Institute for Vision Research, the University of Iowa, Iowa City, IA, 52242, USA.
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Novel genetic features of human and mouse Purkinje cell differentiation defined by comparative transcriptomics. Proc Natl Acad Sci U S A 2020; 117:15085-15095. [PMID: 32546527 PMCID: PMC7334519 DOI: 10.1073/pnas.2000102117] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Comparative transcriptomics between differentiating human pluripotent stem cells (hPSCs) and developing mouse neurons offers a powerful approach to compare genetic and epigenetic pathways in human and mouse neurons. To analyze human Purkinje cell (PC) differentiation, we optimized a protocol to generate human pluripotent stem cell-derived Purkinje cells (hPSC-PCs) that formed synapses when cultured with mouse cerebellar glia and granule cells and fired large calcium currents, measured with the genetically encoded calcium indicator jRGECO1a. To directly compare global gene expression of hPSC-PCs with developing mouse PCs, we used translating ribosomal affinity purification (TRAP). As a first step, we used Tg(Pcp2-L10a-Egfp) TRAP mice to profile actively transcribed genes in developing postnatal mouse PCs and used metagene projection to identify the most salient patterns of PC gene expression over time. We then created a transgenic Pcp2-L10a-Egfp TRAP hPSC line to profile gene expression in differentiating hPSC-PCs, finding that the key gene expression pathways of differentiated hPSC-PCs most closely matched those of late juvenile mouse PCs (P21). Comparative bioinformatics identified classical PC gene signatures as well as novel mitochondrial and autophagy gene pathways during the differentiation of both mouse and human PCs. In addition, we identified genes expressed in hPSC-PCs but not mouse PCs and confirmed protein expression of a novel human PC gene, CD40LG, expressed in both hPSC-PCs and native human cerebellar tissue. This study therefore provides a direct comparison of hPSC-PC and mouse PC gene expression and a robust method for generating differentiated hPSC-PCs with human-specific gene expression for modeling developmental and degenerative cerebellar disorders.
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Voigt AP, Whitmore SS, Mulfaul K, Chirco KR, Giacalone JC, Flamme-Wiese MJ, Stockman A, Stone EM, Tucker BA, Scheetz TE, Mullins RF. Bulk and single-cell gene expression analyses reveal aging human choriocapillaris has pro-inflammatory phenotype. Microvasc Res 2020; 131:104031. [PMID: 32531351 DOI: 10.1016/j.mvr.2020.104031] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 06/02/2020] [Accepted: 06/05/2020] [Indexed: 12/17/2022]
Abstract
The human choroidal vasculature is subject to age-related structural and gene expression changes implicated in age-related macular degeneration (AMD). In this study, we performed both bulk and single-cell RNA sequencing on infant (n = 4 for bulk experiments, n = 2 for single-cell experiments) and adult (n = 13 for bulk experiments, n = 6 for single-cell experiments) human donors to characterize how choroidal gene expression changes with age. Differential expression analysis revealed that aged choroidal samples were enriched in genes encoding pro-inflammatory transcription factors and leukocyte transendothelial cell migration adhesion proteins. Such genes were observed to be differentially expressed specifically within choroidal endothelial cells at the single-cell level. Immunohistochemistry experiments support transcriptional findings that CD34 is elevated in infant choriocapillaris endothelial cells while ICAM-1 is enriched in adults. These results suggest several potential drivers of the pro-inflammatory vascular phenotype observed with advancing age.
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Affiliation(s)
- Andrew P Voigt
- Department of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States of America; Institute for Vision Research, the University of Iowa, Iowa City, IA 52242, United States of America
| | - S Scott Whitmore
- Department of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States of America; Institute for Vision Research, the University of Iowa, Iowa City, IA 52242, United States of America
| | - Kelly Mulfaul
- Department of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States of America; Institute for Vision Research, the University of Iowa, Iowa City, IA 52242, United States of America
| | - Kathleen R Chirco
- Department of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States of America; Institute for Vision Research, the University of Iowa, Iowa City, IA 52242, United States of America
| | - Joseph C Giacalone
- Department of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States of America; Institute for Vision Research, the University of Iowa, Iowa City, IA 52242, United States of America
| | - Miles J Flamme-Wiese
- Department of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States of America; Institute for Vision Research, the University of Iowa, Iowa City, IA 52242, United States of America
| | - Adam Stockman
- Department of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States of America; Iowa Lions Eye Bank, Coralville, IA 52241, United States of America
| | - Edwin M Stone
- Department of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States of America; Institute for Vision Research, the University of Iowa, Iowa City, IA 52242, United States of America
| | - Budd A Tucker
- Department of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States of America; Institute for Vision Research, the University of Iowa, Iowa City, IA 52242, United States of America
| | - Todd E Scheetz
- Department of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States of America; Institute for Vision Research, the University of Iowa, Iowa City, IA 52242, United States of America
| | - Robert F Mullins
- Department of Ophthalmology and Visual Sciences, the University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States of America; Institute for Vision Research, the University of Iowa, Iowa City, IA 52242, United States of America.
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Shen Y, Li M, Liu K, Xu X, Zhu S, Wang N, Guo W, Zhao Q, Lu P, Yu F, Xu X. Integrated bioinformatics analysis of aberrantly-methylated differentially-expressed genes and pathways in age-related macular degeneration. BMC Ophthalmol 2020; 20:119. [PMID: 32209064 PMCID: PMC7092446 DOI: 10.1186/s12886-020-01392-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/13/2020] [Indexed: 11/11/2022] Open
Abstract
Background Age-related macular degeneration (AMD) represents the leading cause of visual impairment in the aging population. The goal of this study was to identify aberrantly-methylated, differentially-expressed genes (MDEGs) in AMD and explore the involved pathways via integrated bioinformatics analysis. Methods Data from expression profile GSE29801 and methylation profile GSE102952 were obtained from the Gene Expression Omnibus database. We analyzed differentially-methylated genes and differentially-expressed genes using R software. Functional enrichment and protein–protein interaction (PPI) network analysis were performed using the R package and Search Tool for the Retrieval of Interacting Genes online database. Hub genes were identified using Cytoscape. Results In total, 827 and 592 genes showed high and low expression, respectively, in GSE29801; 4117 hyper-methylated genes and 511 hypo-methylated genes were detected in GSE102952. Based on overlap, we categorized 153 genes as hyper-methylated, low-expression genes (Hyper-LGs) and 24 genes as hypo-methylated, high-expression genes (Hypo-HGs). Four Hyper-LGs (CKB, PPP3CA, TGFB2, SOCS2) overlapped with AMD risk genes in the Public Health Genomics and Precision Health Knowledge Base. KEGG pathway enrichment analysis indicated that Hypo-HGs were enriched in the calcium signaling pathway, whereas Hyper-LGs were enriched in sphingolipid metabolism. In GO analysis, Hypo-HGs were enriched in fibroblast migration, membrane raft, and coenzyme binding, among others. Hyper-LGs were enriched in mRNA transport, nuclear speck, and DNA binding, among others. In PPI network analysis, 23 nodes and two edges were established from Hypo-HGs, and 151 nodes and 73 edges were established from Hyper-LGs. Hub genes (DHX9, MAPT, PAX6) showed the greatest overlap. Conclusion This study revealed potentially aberrantly MDEGs and pathways in AMD, which might improve the understanding of this disease.
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Affiliation(s)
- Yinchen Shen
- Department of Ophthalmology, Shanghai General Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, 200080, People's Republic of China.,National Clinical Research Center for Eye Diseases, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China
| | - Mo Li
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China
| | - Kun Liu
- Department of Ophthalmology, Shanghai General Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, 200080, People's Republic of China.,National Clinical Research Center for Eye Diseases, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China
| | - Xiaoyin Xu
- Department of Ophthalmology, Shanghai General Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, 200080, People's Republic of China.,National Clinical Research Center for Eye Diseases, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China
| | - Shaopin Zhu
- Department of Ophthalmology, Shanghai General Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, 200080, People's Republic of China.,National Clinical Research Center for Eye Diseases, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China
| | - Ning Wang
- Department of Ophthalmology, Shanghai General Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, 200080, People's Republic of China.,National Clinical Research Center for Eye Diseases, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China
| | - Wenke Guo
- NHC Key Lab. of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Fudan University, Shanghai, China
| | - Qianqian Zhao
- NHC Key Lab. of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Fudan University, Shanghai, China
| | - Ping Lu
- NHC Key Lab. of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Fudan University, Shanghai, China
| | - Fudong Yu
- NHC Key Lab. of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Fudan University, Shanghai, China
| | - Xun Xu
- Department of Ophthalmology, Shanghai General Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, 200080, People's Republic of China. .,National Clinical Research Center for Eye Diseases, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China.
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Garweg JG, Zandi S, Pfister I, Rieben R, Skowronska M, Tappeiner C. Cytokine profiles of phakic and pseudophakic eyes with primary retinal detachment. Acta Ophthalmol 2019; 97:e580-e588. [PMID: 30561135 PMCID: PMC6590374 DOI: 10.1111/aos.13998] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 11/16/2018] [Indexed: 12/31/2022]
Abstract
PURPOSE To compare the cytokine profiles of phakic (p) and pseudophakic (ps) eyes with primary rhegmatogenous retinal detachment (RD) to eyes with macular holes (MH) and to identify differences in the specific cytokine profiles. METHODS Aqueous humour (AH) and vitreous fluid (VF) were obtained from patients with primary RD without proliferative vitreoretinopathy undergoing vitrectomy. AH and VF of patients with macular holes (MH) served as controls. Forty-three different cytokines were quantified using multiplex cytokine analysis. Intergroup and intragroup comparisons were performed. To control for multiple comparisons, Holm's correction was applied. RESULTS VF and AH samples of 71 eyes with RD (pRD N = 38; psRD N = 33) and 26 eyes with MH were included. Cytokine levels in psRD and pRD were similar (none with >10-fold difference). The levels of 39 of 43 cytokines in the VF were significantly higher in eyes with RD than in those with MH (>10-fold: CXLC5, CCL26, CCL1, IL-6, CXCL11, CCL7, CCL13, MIG/CXCL9, CCL19 and TGF-β1). In the AH, 23 of 43 cytokines were significantly higher compared to MH (>10-fold: CXCL5, IL-4, IL-6, IL-8/CXCL8 and CCL7). CONCLUSION A complex, but nonspecific cytokine environmental response seems to initiate immunological and profibrotic processes following RD. Relevant differences in the cytokine profiles of eyes with pRD and psRD were not identified, whereas cytokine differences between AH and VF in RD could be explained by upregulation in the vitreous, a higher turn around in the anterior chamber, or differences in inflammatory cascades in both compartments.
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Affiliation(s)
- Justus G. Garweg
- Swiss Eye Institute and Clinic for Vitreoretinal Diseases Berner Augenklinik am Lindenhofspital Bern Switzerland
- Department of Ophthalmology, Inselspital Bern University Hospital University of Bern Bern Switzerland
| | - Souska Zandi
- Swiss Eye Institute and Clinic for Vitreoretinal Diseases Berner Augenklinik am Lindenhofspital Bern Switzerland
| | - Isabel Pfister
- Swiss Eye Institute and Clinic for Vitreoretinal Diseases Berner Augenklinik am Lindenhofspital Bern Switzerland
| | - Robert Rieben
- Department for BioMedical Research University of Bern Bern Switzerland
| | - Magdalena Skowronska
- Swiss Eye Institute and Clinic for Vitreoretinal Diseases Berner Augenklinik am Lindenhofspital Bern Switzerland
- Department for BioMedical Research University of Bern Bern Switzerland
| | - Christoph Tappeiner
- Department of Ophthalmology, Inselspital Bern University Hospital University of Bern Bern Switzerland
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Luna G, Lewis GP, Linberg KA, Chang B, Hu Q, Munson PJ, Maminishkis A, Miller SS, Fisher SK. Anatomical and Gene Expression Changes in the Retinal Pigmented Epithelium Atrophy 1 (rpea1) Mouse: A Potential Model of Serous Retinal Detachment. Invest Ophthalmol Vis Sci 2017; 57:4641-54. [PMID: 27603725 PMCID: PMC5113314 DOI: 10.1167/iovs.15-19044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Purpose The purpose of this study was to examine the rpea1 mouse whose retina spontaneously detaches from the underlying RPE as a potential model for studying the cellular effects of serous retinal detachment (SRD). Methods Optical coherence tomography (OCT) was performed immediately prior to euthanasia; retinal tissue was subsequently prepared for Western blotting, microarray analysis, immunocytochemistry, and light and electron microscopy (LM, EM). Results By postnatal day (P) 30, OCT, LM, and EM revealed the presence of small shallow detachments that increased in number and size over time. By P60 in regions of detachment, there was a dramatic loss of PNA binding around cones in the interphotoreceptor matrix and a concomitant increase in labeling of the outer nuclear layer and rod synaptic terminals. Retinal pigment epithelium wholemounts revealed a patchy loss in immunolabeling for both ezrin and aquaporin 1. Anti-ezrin labeling was lost from small regions of the RPE apical surface underlying detachments at P30. Labeling for tight-junction proteins provided a regular array of profiles outlining the periphery of RPE cells in wild-type tissue, however, this pattern was disrupted in the mutant as early as P30. Microarray analysis revealed a broad range of changes in genes involved in metabolism, signaling, cell polarity, and tight-junction organization. Conclusions These data indicate changes in this mutant mouse that may provide clues to the underlying mechanisms of SRD in humans. Importantly, these changes include the production of multiple spontaneous detachments without the presence of a retinal tear or significant degeneration of outer segments, changes in the expression of proteins involved in adhesion and fluid transport, and a disrupted organization of RPE tight junctions that may contribute to the formation of focal detachments.
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Affiliation(s)
- Gabriel Luna
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, California, United States 2Center for Bio-Image Informatics, University of California Santa Barbara, Santa Barbara, California, United States
| | - Geoffrey P Lewis
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, California, United States 2Center for Bio-Image Informatics, University of California Santa Barbara, Santa Barbara, California, United States
| | - Kenneth A Linberg
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, California, United States
| | - Bo Chang
- The Jackson Laboratory, Bar Harbor, Maine, United States
| | - Quiri Hu
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, California, United States
| | - Peter J Munson
- Mathematical and Statistical Computing Laboratory, Center for Information Technology, National Institutes of Health, Bethesda, Maryland, United States
| | - Arvydas Maminishkis
- The National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Sheldon S Miller
- The National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Steven K Fisher
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, California, United States 2Center for Bio-Image Informatics, University of California Santa Barbara, Santa Barbara, California, United States 6Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, California, United States
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Tian L, Kazmierkiewicz KL, Bowman AS, Li M, Curcio CA, Stambolian DE. Transcriptome of the human retina, retinal pigmented epithelium and choroid. Genomics 2015; 105:253-64. [PMID: 25645700 DOI: 10.1016/j.ygeno.2015.01.008] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 01/23/2015] [Accepted: 01/24/2015] [Indexed: 10/24/2022]
Abstract
The retina and its adjacent supporting tissues - retinal pigmented epithelium (RPE) and choroid - are critical structures in human eyes required for normal visual perception. Abnormal changes in these layers have been implicated in diseases such as age-related macular degeneration and glaucoma. With the advent of high-throughput methods, such as serial analysis of gene expression, cDNA microarray, and RNA sequencing, there is unprecedented opportunity to facilitate our understanding of the normal retina, RPE, and choroid. This information can be used to identify dysfunction in age-related macular degeneration and glaucoma. In this review, we describe the current status in our understanding of these transcriptomes through the use of high-throughput techniques.
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Affiliation(s)
- Lifeng Tian
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, Pa 19104, USA.
| | | | - Anita S Bowman
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pa 19104, USA.
| | - Mingyao Li
- Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, Pa 19104, USA.
| | - Christine A Curcio
- Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, Al 35294, USA.
| | - Dwight E Stambolian
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pa 19104, USA.
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Transcriptomic analysis across nasal, temporal, and macular regions of human neural retina and RPE/choroid by RNA-Seq. Exp Eye Res 2014; 129:93-106. [PMID: 25446321 DOI: 10.1016/j.exer.2014.11.001] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Revised: 10/31/2014] [Accepted: 11/04/2014] [Indexed: 12/27/2022]
Abstract
Proper spatial differentiation of retinal cell types is necessary for normal human vision. Many retinal diseases, such as Best disease and male germ cell associated kinase (MAK)-associated retinitis pigmentosa, preferentially affect distinct topographic regions of the retina. While much is known about the distribution of cell types in the retina, the distribution of molecular components across the posterior pole of the eye has not been well-studied. To investigate regional difference in molecular composition of ocular tissues, we assessed differential gene expression across the temporal, macular, and nasal retina and retinal pigment epithelium (RPE)/choroid of human eyes using RNA-Seq. RNA from temporal, macular, and nasal retina and RPE/choroid from four human donor eyes was extracted, poly-A selected, fragmented, and sequenced as 100 bp read pairs. Digital read files were mapped to the human genome and analyzed for differential expression using the Tuxedo software suite. Retina and RPE/choroid samples were clearly distinguishable at the transcriptome level. Numerous transcription factors were differentially expressed between regions of the retina and RPE/choroid. Photoreceptor-specific genes were enriched in the peripheral samples, while ganglion cell and amacrine cell genes were enriched in the macula. Within the RPE/choroid, RPE-specific genes were upregulated at the periphery while endothelium associated genes were upregulated in the macula. Consistent with previous studies, BEST1 expression was lower in macular than extramacular regions. The MAK gene was expressed at lower levels in macula than in extramacular regions, but did not exhibit a significant difference between nasal and temporal retina. The regional molecular distinction is greatest between macula and periphery and decreases between different peripheral regions within a tissue. Datasets such as these can be used to prioritize candidate genes for possible involvement in retinal diseases with regional phenotypes.
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Morgan DJ, DeAngelis MM. Differential Gene Expression in Age-Related Macular Degeneration. Cold Spring Harb Perspect Med 2014; 5:a017210. [PMID: 25342062 DOI: 10.1101/cshperspect.a017210] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Gene expression is the first step in ascribing function between an associated gene and disease. Understanding how variation in a gene influences expression, particularly in tissues affected by the disease, may help elucidate what influences the phenotypic outcome of that disease. Previous studies of the genetics of age-related macular degeneration (AMD) have identified several risk factors, but have not yet bridged the gap between gene association and identifying a specific mechanism or function that is involved in the pathogenesis of AMD. Advances in genomic technologies, such as RNA sequencing (RNA-seq), single cell RNA-seq, bilsulfite sequencing, and/or whole genome methylation, will be powerful tools for identifying genes/pathways that are differentially expressed in those with AMD versus those without AMD. These technologies should advance the field of AMD research so that appropriate preventive and therapeutic targets can be developed.
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Affiliation(s)
- Denise J Morgan
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, Utah 84132
| | - Margaret M DeAngelis
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, Utah 84132
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Ressler SJ, Dang TD, Wu SM, Tse DY, Gilbert BE, Vyakarnam A, Yang F, Schauer IG, Barron DA, Rowley DR. WFDC1 is a key modulator of inflammatory and wound repair responses. THE AMERICAN JOURNAL OF PATHOLOGY 2014; 184:2951-64. [PMID: 25219356 DOI: 10.1016/j.ajpath.2014.07.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Revised: 07/19/2014] [Accepted: 07/24/2014] [Indexed: 12/16/2022]
Abstract
WFDC1/ps20 is a whey acidic protein four-disulfide core member that exhibits diverse growth and immune-associated functions in vitro. In vivo functions are unknown, although WFDC1 is lower in reactive stroma. A Wfdc1-null mouse was generated to assess core functions. Wfdc1-null mice exhibited normal developmental and adult phenotypes. However, homeostasis challenges affected inflammatory and repair processes. Wfdc1-null mice infected with influenza A exhibited 2.75-log-fold lower viral titer relative to control mice. Wfdc1-null infected lungs exhibited elevated macrophages and deposition of osteopontin, a potent macrophage chemokine. In wounding studies, Wfdc1-null mice exhibited an elevated rate of skin closure, and this too was associated with elevated deposition of osteopontin and macrophage recruitment. Wfdc1-null fibroblasts exhibited impaired spheroid formation, elevated adhesion to fibronectin, and an increased rate of wound closure in vitro. This was reversed by neutralizing antibody to osteopontin. Osteopontin mRNA and cleaved protein was up-regulated in Wfdc1-null cells treated with lipopolysaccharide or polyinosinic-polycytidylic acid coordinate with constitutively active matrix metallopeptidase-9 (MMP-9), a protease that cleaves osteopontin. These data suggest that WFDC1/ps20 modulates core host response mechanisms, in part, via regulation of osteopontin and MMP-9 activity. Release from WFDC1 regulation is likely a key component of inflammatory and repair response mechanisms, and involves the processing of elevated osteopontin by activated MMP-9, and subsequent macrophage recruitment.
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Affiliation(s)
- Steven J Ressler
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas
| | - Truong D Dang
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas
| | - Samuel M Wu
- Department of Ophthalmology, Baylor College of Medicine, Houston, Texas
| | - Dennis Y Tse
- Department of Ophthalmology, Baylor College of Medicine, Houston, Texas
| | - Brian E Gilbert
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas
| | - Annapurna Vyakarnam
- Department of Infectious Diseases, King's College London, London, United Kingdom
| | - Feng Yang
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas
| | - Isaiah G Schauer
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas
| | - David A Barron
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas
| | - David R Rowley
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas.
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Pasaporte MS, Rabaya FJR, Toleco MM, Flores DM. Xanthophyll content of selected vegetables commonly consumed in the Philippines and the effect of boiling. Food Chem 2014; 158:35-40. [DOI: 10.1016/j.foodchem.2014.02.090] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 01/29/2014] [Accepted: 02/18/2014] [Indexed: 11/24/2022]
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Sadigh S, Luo X, Cideciyan AV, Sumaroka A, Boxley SL, Hall LM, Sheplock R, Feuer WJ, Stambolian DS, Jacobson SG. Drusen and photoreceptor abnormalities in African-Americans with intermediate non-neovascular age-related macular degeneration. Curr Eye Res 2014; 40:398-406. [PMID: 24912073 DOI: 10.3109/02713683.2014.925934] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE/AIM To investigate the relationship of drusen and photoreceptor abnormalities in African-American (AA) patients with intermediate non-neovascular age-related macular degeneration (AMD). MATERIALS AND METHODS AA patients with intermediate AMD (n = 11; age 52-77 years) were studied with spectral-domain optical coherence tomography. Macular location and characteristics of large drusen (≥125 µm) were determined. Thickness of photoreceptor laminae was quantified overlying drusen and in other macular regions. A patient with advanced AMD (age 87) was included to illustrate the disease spectrum. RESULTS In this AA patient cohort, the spectrum of changes known to occur in AMD, including large drusen, sub-retinal drusenoid deposits and geographic atrophy, were identified. In intermediate AMD eyes (n = 17), there were 183 large drusen, the majority of which were pericentral in location. Overlying the drusen there was significant thinning of the photoreceptor outer nuclear layer (termed ONL(+)) as well as the inner and outer segments (IS + OS). The reductions in IS + OS thickness were directly related to ONL(+) thickness. In a fraction (∼8%) of paradrusen locations with normal lamination sampled within ∼280 µm of peak drusen height, ONL(+) was significantly thickened compared to age and retinal-location-matched normal values. Topographical maps of the macula confirmed ONL thickening in regions neighboring and distant to large drusen. CONCLUSIONS We confirm there is a pericentral distribution of drusen across AA-AMD maculae rather than the central localization in Caucasian AMD. Reductions in the photoreceptor laminae overlying drusen are evident. ONL(+) thickening in some macular areas of AA-AMD eyes may be an early phenotypic marker for photoreceptor stress.
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Affiliation(s)
- Sam Sadigh
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania , Philadelphia, PA , USA
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Buchholz DE, Pennington BO, Croze RH, Hinman CR, Coffey PJ, Clegg DO. Rapid and efficient directed differentiation of human pluripotent stem cells into retinal pigmented epithelium. Stem Cells Transl Med 2013; 2:384-93. [PMID: 23599499 DOI: 10.5966/sctm.2012-0163] [Citation(s) in RCA: 187] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Controlling the differentiation of human pluripotent stem cells is the goal of many laboratories, both to study normal human development and to generate cells for transplantation. One important cell type under investigation is the retinal pigmented epithelium (RPE). Age-related macular degeneration (AMD), the leading cause of blindness in the Western world, is caused by dysfunction and death of the RPE. Currently, RPE derived from human embryonic stem cells are in clinical trials for the treatment of AMD. Although protocols to generate RPE from human pluripotent stem cells have become more efficient since the first report in 2004, they are still time-consuming and relatively inefficient. We have found that the addition of defined factors at specific times leads to conversion of approximately 80% of the cells to an RPE phenotype in only 14 days. This protocol should be useful for rapidly generating RPE for transplantation as well as for studying RPE development in vitro.
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Affiliation(s)
- David E Buchholz
- Center for Stem Cell Biology and Engineering, University of California, Santa Barbara, CA, USA
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25
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Dobner BC, Riechardt AI, Joussen AM, Englert S, Bechrakis NE. Expression of haematogenous and lymphogenous chemokine receptors and their ligands on uveal melanoma in association with liver metastasis. Acta Ophthalmol 2012; 90:e638-44. [PMID: 23164171 DOI: 10.1111/j.1755-3768.2012.02515.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
PURPOSE Chemokine receptors and their ligands are involved in a number of cell processes, including normal cell trafficking as well as metastasis in cancer. During metastasis, they are thought to play a role in determining cancer cell distribution and target organs. The aim of this study was to examine the expression of the chemokine receptors CXCR4, CCR7 and CCR10 as well as their respective chemokine ligands (CXCL12, CCL19, CCL27) in human uveal melanomas. METHODS Seventy formalin-fixed paraffin-embedded uveal melanoma specimens from patients treated in 1996-1997 were examined using immunohistochemistry and evaluated using an immune reactive score (IRS). RESULTS The chemokine receptors CXCR4, CCR7 and CCR10 were primarily expressed in the cytoplasm of uveal melanoma cells, with CXCR4 (average IRS 8.2) and CCR7 (average IRS 5.7) showing the strongest expression, respectively. The chemokine ligand CCL19 demonstrated a moderate expression (average IRS 5.3), whereas the expression of receptor CCR10 (average IRS of 3.4), ligand CCL27 (average IRS 2.5) and ligand CXCL12 (average IRS 0.6) by uveal melanoma cells was low. A significant association between liver metastases and chemokine expression was found for CCR7 expression (p = 0.037) only. Comparison of liver metastasis and choroid uveal melanoma (35.3%, n = 12 of 34) versus ciliary body involvement (72.7%, n = 8 of 11) was significant (p = 0.030). CONCLUSION Chemokine receptors are more strongly expressed on uveal melanoma cells than their ligands. Our results show new aspects of the metastatic process in uveal melanoma.
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Affiliation(s)
- Bianca C Dobner
- Department of Ophthalmology, University of Heidelberg, Heidelberg, Germany.
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26
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Cai H, Fields MA, Hoshino R, Priore LVD. Effects of aging and anatomic location on gene expression in human retina. Front Aging Neurosci 2012; 4:8. [PMID: 22666212 PMCID: PMC3364488 DOI: 10.3389/fnagi.2012.00008] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 05/10/2012] [Indexed: 01/24/2023] Open
Abstract
OBJECTIVE To determine the effects of age and topographic location on gene expression in human neural retina. METHODS Macular and peripheral neural retina RNA was isolated from human donor eyes for DNA microarray and quantitative RT-PCR analyses. RESULTS Total RNA integrity from human donors was preserved. Hierarchical clustering analysis demonstrates that the gene expression profiles of young, old, macula, and peripheral retina cluster into four distinct groups. Genes which are highly expressed in macular, peripheral, young, or old retina were identified, including inhibitors of Wnt Signaling Pathway (DKK1, FZD10, and SFRP2) which are preferably expressed in the periphery. CONCLUSION The transcriptome of the human retina is affected by age and topographic location. Wnt pathway inhibitors in the periphery may maintain peripheral retinal cells in an undifferentiated state. Understanding the effects of age and topographic location on gene expression may lead to the development of new therapeutic interventions for age-related eye diseases.
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Affiliation(s)
- Hui Cai
- Department of Ophthalmology, Harkness Eye Institute, Columbia University, New York NY, USA
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Rowland TJ, Blaschke AJ, Buchholz DE, Hikita ST, Johnson LV, Clegg DO. Differentiation of human pluripotent stem cells to retinal pigmented epithelium in defined conditions using purified extracellular matrix proteins. J Tissue Eng Regen Med 2012; 7:642-53. [PMID: 22514096 DOI: 10.1002/term.1458] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 10/05/2011] [Accepted: 11/24/2011] [Indexed: 01/24/2023]
Abstract
A potential application of human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) is the generation of retinal pigmented epithelium (RPE) to treat age-related macular degeneration (AMD), a common but incurable retinal disease. RPE cells derived from hESCs (hESC-RPEs) and iPSCs (iPSC-RPEs) express essential RPE markers and can rescue visual function in animal models. However, standard differentiation protocols yield RPE cells at low frequency, especially from iPSC lines, and the common use of Matrigel and xenogeneic feeder cells is not compatible with clinical applications. The extracellular matrix (ECM) can affect differentiation, and therefore changes in ECM composition may improve the frequency of stem cell-RPE differentiation. We selected several purified ECM proteins and substrates, based on the in vivo RPE ECM environment, and tested their ability to support iPSC-RPE differentiation and maintenance. iPSCs differentiated on nearly all tested substrates developed pigmented regions, with Matrigel and mouse laminin-111 supporting the highest pigmentation frequencies. Although iPSC-RPEs cultured on the majority of the tested substrates expressed key RPE genes, only six substrates supported development of confluent monolayers with normal RPE morphology, including Matrigel and mouse laminin-111. iPSCs differentiated on mouse laminin-111 produced iPSC-RPEs expressing RPE proteins, and hESCs differentiated on mouse laminin-111 resulted in high yields of functional hESC-RPEs. This identification of key ECM proteins may assist with future scaffold designs and provide peptide sequences for use in synthetic, xeno-free, GMP-compliant generation of RPE from human pluripotent stem cells relevant to clinical translation.
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Affiliation(s)
- Teisha J Rowland
- Center for Stem Cell Biology and Engineering, University of California, Santa Barbara, CA 93106, USA
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28
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Bandyopadhyay M, Rohrer B. Matrix metalloproteinase activity creates pro-angiogenic environment in primary human retinal pigment epithelial cells exposed to complement. Invest Ophthalmol Vis Sci 2012; 53:1953-61. [PMID: 22408008 DOI: 10.1167/iovs.11-8638] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
PURPOSE Mechanistic studies have shown that inflammation, complement activation, extracellular matrix (ECM) turnover, growth factor imbalance, and oxidative stress are fundamental components of age-related macular degeneration (AMD). Matrix metalloproteinases (MMPs) mediate ECM turnover but also process various bioactive molecules. Here, we tested whether complement attack on RPE monolayers changes MMP secretion and activation, thereby altering the availability of growth factors in the extracellular space. METHODS Human embryonic RPE monolayers with stable transepithelial resistance (TER) were established. Complement activation was induced with H₂O₂ and normal human serum. MMP-2/9, vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF) protein, and mRNA levels were analyzed by Western blotting, ELISA, and real-time PCR; activity of MMP-2/9 by gelatin zymography. RESULTS Complement activation resulted in a loss of TER, which required transient membrane attack complex formation, activation of the alternative pathway, and VEGF secretion and signaling. Despite the generation of reactive oxygen species, cellular integrity or intracellular adenosine triphosphate (ATP) levels were unaffected. However, expression of MMP-2/9 and their protease activity was elevated. Inhibition of MMP-2/9 activity increased PEDF and decreased VEGF levels in the apical and basal supernatants but had no effect on their expression levels. VEGF levels in the supernatant correlated with the level TER reduction. CONCLUSIONS These studies suggest that complement activation, by altering the expression and activation of MMPs, has the ability to generate a proangiogenic environment by altering the balance between VEGF and PEDF. Our findings link reported results that have been associated with AMD pathogenesis; oxidative stress; complement activation; VEGF/PEDF ratio; and MMP activity.
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Affiliation(s)
- Mausumi Bandyopadhyay
- Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA
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29
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Whitmore SS, Mullins RF. Transcriptome changes in age-related macular degeneration. BMC Med 2012; 10:21. [PMID: 22369667 PMCID: PMC3307472 DOI: 10.1186/1741-7015-10-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 02/27/2012] [Indexed: 12/03/2022] Open
Abstract
Age-related macular degeneration (AMD) is a debilitating, common cause of visual impairment. While the last decade has seen great progress in understanding the pathophysiology of AMD, the molecular changes that occur in eyes with AMD are still poorly understood. In the current issue of Genome Medicine, Newman and colleagues present the first systematic transcriptional profile analysis of AMD-affected tissues, providing a comprehensive set of expression data for different regions (macula versus periphery), tissues (retina versus retinal pigment epithelium (RPE)/choroid), and disease state (control versus early or advanced AMD). Their findings will serve as a foundation for additional systems-level research into the pathogenesis of this blinding disease.
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Affiliation(s)
- S Scott Whitmore
- Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, 4135E MERF, 375 Newton Rd, Iowa City, IA 52242, USA
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30
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Newman AM, Gallo NB, Hancox LS, Miller NJ, Radeke CM, Maloney MA, Cooper JB, Hageman GS, Anderson DH, Johnson LV, Radeke MJ. Systems-level analysis of age-related macular degeneration reveals global biomarkers and phenotype-specific functional networks. Genome Med 2012; 4:16. [PMID: 22364233 PMCID: PMC3372225 DOI: 10.1186/gm315] [Citation(s) in RCA: 178] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 01/18/2012] [Accepted: 02/24/2012] [Indexed: 12/26/2022] Open
Abstract
UNLABELLED Please see related commentary: http://www.biomedcentral.com/1741-7015/10/21/abstract BACKGROUND Age-related macular degeneration (AMD) is a leading cause of blindness that affects the central region of the retinal pigmented epithelium (RPE), choroid, and neural retina. Initially characterized by an accumulation of sub-RPE deposits, AMD leads to progressive retinal degeneration, and in advanced cases, irreversible vision loss. Although genetic analysis, animal models, and cell culture systems have yielded important insights into AMD, the molecular pathways underlying AMD's onset and progression remain poorly delineated. We sought to better understand the molecular underpinnings of this devastating disease by performing the first comparative transcriptome analysis of AMD and normal human donor eyes. METHODS RPE-choroid and retina tissue samples were obtained from a common cohort of 31 normal, 26 AMD, and 11 potential pre-AMD human donor eyes. Transcriptome profiles were generated for macular and extramacular regions, and statistical and bioinformatic methods were employed to identify disease-associated gene signatures and functionally enriched protein association networks. Selected genes of high significance were validated using an independent donor cohort. RESULTS We identified over 50 annotated genes enriched in cell-mediated immune responses that are globally over-expressed in RPE-choroid AMD phenotypes. Using a machine learning model and a second donor cohort, we show that the top 20 global genes are predictive of AMD clinical diagnosis. We also discovered functionally enriched gene sets in the RPE-choroid that delineate the advanced AMD phenotypes, neovascular AMD and geographic atrophy. Moreover, we identified a graded increase of transcript levels in the retina related to wound response, complement cascade, and neurogenesis that strongly correlates with decreased levels of phototransduction transcripts and increased AMD severity. Based on our findings, we assembled protein-protein interactomes that highlight functional networks likely to be involved in AMD pathogenesis. CONCLUSIONS We discovered new global biomarkers and gene expression signatures of AMD. These results are consistent with a model whereby cell-based inflammatory responses represent a central feature of AMD etiology, and depending on genetics, environment, or stochastic factors, may give rise to the advanced AMD phenotypes characterized by angiogenesis and/or cell death. Genes regulating these immunological activities, along with numerous other genes identified here, represent promising new targets for AMD-directed therapeutics and diagnostics.
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Affiliation(s)
- Aaron M Newman
- Center for the Study of Macular Degeneration, Neuroscience Research Institute,
Biological Sciences 2 Building, University of California, Santa Barbara, CA
93106-5060, USA
- Current address: Institute for Stem Cell Biology and Regenerative Medicine,
Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305,
USA
| | - Natasha B Gallo
- Center for the Study of Macular Degeneration, Neuroscience Research Institute,
Biological Sciences 2 Building, University of California, Santa Barbara, CA
93106-5060, USA
| | - Lisa S Hancox
- Department of Ophthalmology and Visual Sciences, University of Iowa, 200 Hawkins
Drive Iowa City, IA 52242-1109, USA
| | - Norma J Miller
- Department of Ophthalmology and Visual Sciences, John A Moran Eye Center,
University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT 84132-5230,
USA
| | - Carolyn M Radeke
- Center for the Study of Macular Degeneration, Neuroscience Research Institute,
Biological Sciences 2 Building, University of California, Santa Barbara, CA
93106-5060, USA
| | - Michelle A Maloney
- Center for the Study of Macular Degeneration, Neuroscience Research Institute,
Biological Sciences 2 Building, University of California, Santa Barbara, CA
93106-5060, USA
| | - James B Cooper
- Molecular, Cellular, and Developmental Biology Department, Life Sciences Building,
University of California, Santa Barbara, CA 93106-9610, USA
| | - Gregory S Hageman
- Department of Ophthalmology and Visual Sciences, John A Moran Eye Center,
University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT 84132-5230,
USA
| | - Don H Anderson
- Center for the Study of Macular Degeneration, Neuroscience Research Institute,
Biological Sciences 2 Building, University of California, Santa Barbara, CA
93106-5060, USA
| | - Lincoln V Johnson
- Center for the Study of Macular Degeneration, Neuroscience Research Institute,
Biological Sciences 2 Building, University of California, Santa Barbara, CA
93106-5060, USA
| | - Monte J Radeke
- Center for the Study of Macular Degeneration, Neuroscience Research Institute,
Biological Sciences 2 Building, University of California, Santa Barbara, CA
93106-5060, USA
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Abstract
The present evaluates the key features of the WFDC1 [WAP (whey acidic protein) four disulfide core 1] gene that encodes ps20 (20 kDa prostate stromal protein), a member of the WAP family. ps20 was first characterized as a growth inhibitory activity that was secreted by fetal urogenital sinus mesenchymal cells. Purified ps20 exhibited several activities that centre on cell adhesion, migration and proliferation. The WFDC1 gene was cloned, contained seven exons, and was mapped to chromosome 16q24, suggesting that it may function as a tumour suppressor; however, direct evidence of this has not emerged. In vivo, ps20 stimulated angiogenesis, although expression of WFDC1/ps20 was down-regulated in the reactive stroma tumour microenvironment in prostate cancer. WFDC1 expression is differential in other cancers and inflammatory conditions. Recent studies point to a role in viral infectivity. Although mechanisms of action are not fully understood, WFDC1/ps20 is emerging as a secreted matricellular protein that probably affects response to micro-organisms and tissue repair homoeostasis.
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Lachke SA, Maas RL. Building the developmental oculome: systems biology in vertebrate eye development and disease. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2011; 2:305-323. [PMID: 20836031 DOI: 10.1002/wsbm.59] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The vertebrate eye is a sophisticated multicomponent organ that has been actively studied for over a century, resulting in the identification of the major embryonic and molecular events involved in its complex developmental program. Data gathered so far provides sufficient information to construct a rudimentary network of the various signaling molecules, transcription factors, and their targets for several key stages of this process. With the advent of genomic technologies, there has been a rapid expansion in our ability to collect and process biological information, and the use of systems-level approaches to study specific aspects of vertebrate eye development has already commenced. This is beginning to result in the definition of the dynamic developmental networks that operate in ocular tissues, and the interactions of such networks between coordinately developing ocular tissues. Such an integrative understanding of the eye by a comprehensive systems-level analysis can be termed the 'oculome', and that of serial developmental stages of the eye as it transits from its initiation to a fully formed functional organ represents the 'developmental oculome'. Construction of the developmental oculome will allow novel mechanistic insights that are essential for organ regeneration-based therapeutic applications, and the generation of computational models for eye disease states to predict the effects of drugs. This review discusses our present understanding of two of the individual components of the developing vertebrate eye--the lens and retina--at both the molecular and systems levels, and outlines the directions and tools required for construction of the developmental oculome.
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Affiliation(s)
- Salil A Lachke
- Division of Genetics, Brigham & Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Richard L Maas
- Division of Genetics, Brigham & Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
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Booij JC, ten Brink JB, Swagemakers SMA, Verkerk AJMH, Essing AHW, van der Spek PJ, Bergen AAB. A new strategy to identify and annotate human RPE-specific gene expression. PLoS One 2010; 5:e9341. [PMID: 20479888 PMCID: PMC2866542 DOI: 10.1371/journal.pone.0009341] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Accepted: 01/27/2010] [Indexed: 01/15/2023] Open
Abstract
Background To identify and functionally annotate cell type-specific gene expression in the human retinal pigment epithelium (RPE), a key tissue involved in age-related macular degeneration and retinitis pigmentosa. Methodology RPE, photoreceptor and choroidal cells were isolated from selected freshly frozen healthy human donor eyes using laser microdissection. RNA isolation, amplification and hybridization to 44 k microarrays was carried out according to Agilent specifications. Bioinformatics was carried out using Rosetta Resolver, David and Ingenuity software. Principal Findings Our previous 22 k analysis of the RPE transcriptome showed that the RPE has high levels of protein synthesis, strong energy demands, is exposed to high levels of oxidative stress and a variable degree of inflammation. We currently use a complementary new strategy aimed at the identification and functional annotation of RPE-specific expressed transcripts. This strategy takes advantage of the multilayered cellular structure of the retina and overcomes a number of limitations of previous studies. In triplicate, we compared the transcriptomes of RPE, photoreceptor and choroidal cells and we deduced RPE specific expression. We identified at least 114 entries with RPE-specific gene expression. Thirty-nine of these 114 genes also show high expression in the RPE, comparison with the literature showed that 85% of these 39 were previously identified to be expressed in the RPE. In the group of 114 RPE specific genes there was an overrepresentation of genes involved in (membrane) transport, vision and ophthalmic disease. More fundamentally, we found RPE-specific involvement in the RAR-activation, retinol metabolism and GABA receptor signaling pathways. Conclusions In this study we provide a further specification and understanding of the RPE transcriptome by identifying and analyzing genes that are specifically expressed in the RPE.
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Affiliation(s)
- Judith C. Booij
- Department of Clinical and Molecular Ophthalmogenetics, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Jacoline B. ten Brink
- Department of Clinical and Molecular Ophthalmogenetics, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Sigrid M. A. Swagemakers
- Department of Bioinformatics and Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
- Cancer Genomics Centre, Erasmus Medical Center, Rotterdam, The Netherlands
| | | | - Anke H. W. Essing
- Department of Clinical and Molecular Ophthalmogenetics, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Peter J. van der Spek
- Department of Bioinformatics and Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Arthur A. B. Bergen
- Department of Clinical and Molecular Ophthalmogenetics, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
- Clinical Genetics Academic Medical Centre Amsterdam, University of Amsterdam, The Netherlands
- Department of Ophthalmology, Academic Medical Centre Amsterdam, University of Amsterdam, The Netherlands
- * E-mail:
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OKAMOTO H, UMEDA S, NOZAWA T, SUZUKI MT, YOSHIKAWA Y, MATSUURA ET, IWATA T. Comparative Proteomic Analyses of Macular and Peripheral Retina of Cynomolgus Monkeys (Macaca fascicularis). Exp Anim 2010; 59:171-82. [DOI: 10.1538/expanim.59.171] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Affiliation(s)
- Haru OKAMOTO
- Division of Molecular & Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center
- Department of Advanced Biosciences, Ochanomizu University
| | - Shinsuke UMEDA
- Division of Molecular & Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center
| | | | | | - Yasuhiro YOSHIKAWA
- Department of Biomedical Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo
| | | | - Takeshi IWATA
- Division of Molecular & Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center
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Anderson DH, Radeke MJ, Gallo NB, Chapin EA, Johnson PT, Curletti CR, Hancox LS, Hu J, Ebright JN, Malek G, Hauser MA, Rickman CB, Bok D, Hageman GS, Johnson LV. The pivotal role of the complement system in aging and age-related macular degeneration: hypothesis re-visited. Prog Retin Eye Res 2009; 29:95-112. [PMID: 19961953 DOI: 10.1016/j.preteyeres.2009.11.003] [Citation(s) in RCA: 565] [Impact Index Per Article: 37.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
During the past ten years, dramatic advances have been made in unraveling the biological bases of age-related macular degeneration (AMD), the most common cause of irreversible blindness in western populations. In that timeframe, two distinct lines of evidence emerged which implicated chronic local inflammation and activation of the complement cascade in AMD pathogenesis. First, a number of complement system proteins, complement activators, and complement regulatory proteins were identified as molecular constituents of drusen, the hallmark extracellular deposits associated with early AMD. Subsequently, genetic studies revealed highly significant statistical associations between AMD and variants of several complement pathway-associated genes including: Complement factor H (CFH), complement factor H-related 1 and 3 (CFHR1 and CFHR3), complement factor B (CFB), complement component 2 (C2), and complement component 3 (C3). In this article, we revisit our original hypothesis that chronic local inflammatory and immune-mediated events at the level of Bruch's membrane play critical roles in drusen biogenesis and, by extension, in the pathobiology of AMD. Secondly, we report the results of a new screening for additional AMD-associated polymorphisms in a battery of 63 complement-related genes. Third, we identify and characterize the local complement system in the RPE-choroid complex - thus adding a new dimension of biological complexity to the role of the complement system in ocular aging and AMD. Finally, we evaluate the most salient, recent evidence that bears directly on the role of complement in AMD pathogenesis and progression. Collectively, these recent findings strongly re-affirm the importance of the complement system in AMD. They lay the groundwork for further studies that may lead to the identification of a transcriptional disease signature of AMD, and hasten the development of new therapeutic approaches that will restore the complement-modulating activity that appears to be compromised in genetically susceptible individuals.
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Affiliation(s)
- Don H Anderson
- Center for the Study of Macular Degeneration, Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA.
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Buchholz DE, Hikita ST, Rowland TJ, Friedrich AM, Hinman CR, Johnson LV, Clegg DO. Derivation of Functional Retinal Pigmented Epithelium from Induced Pluripotent Stem Cells. Stem Cells 2009; 27:2427-34. [DOI: 10.1002/stem.189] [Citation(s) in RCA: 332] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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A mutation of the WFDC1 gene is responsible for multiple ocular defects in cattle. Genomics 2009; 94:55-62. [DOI: 10.1016/j.ygeno.2009.04.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2009] [Revised: 04/07/2009] [Accepted: 04/08/2009] [Indexed: 11/18/2022]
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Expression of the diabetes risk gene wolframin (WFS1) in the human retina. Exp Eye Res 2009; 89:568-74. [PMID: 19523951 DOI: 10.1016/j.exer.2009.05.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2009] [Revised: 05/26/2009] [Accepted: 05/27/2009] [Indexed: 11/21/2022]
Abstract
Wolfram syndrome 1 (WFS1, OMIM 222300), a rare genetic disorder characterized by optic nerve atrophy, deafness, diabetes insipidus and diabetes mellitus, is caused by mutations of WFS1, encoding WFS1/wolframin. Non-syndromic WFS1 variants are associated with the risk of diabetes mellitus due to altered function of wolframin in pancreatic islet cells, expanding the importance of wolframin. This study extends a previous report for the monkey retina, using immunohistochemistry to localize wolframin on cryostat and paraffin sections of human retina. In addition, the human retinal pigment epithelial (RPE) cell line termed ARPE-19 and retinas from both pigmented and albino mice were studied to assess wolframin localization. In the human retina, wolframin was expressed in retinal ganglion cells, optic axons and the proximal optic nerve. Wolframin expression in the human retinal pigment epithelium (RPE) was confirmed with intense cytoplasmic labeling in ARPE-19 cells. Strong labeling of the RPE was also found in the albino mouse retina. Cryostat sections of the mouse retina showed a more extended pattern of wolframin labeling, including the inner nuclear layer (INL) and photoreceptor inner segments, confirming the recent report of Kawano et al. [Kawano, J., Tanizawa, Y., Shinoda, K., 2008. Wolfram syndrome 1 (Wfs1) gene expression in the normal mouse visual system. J. Comp. Neurol. 510, 1-23]. Absence of these cells in the human specimens despite the use of human-specific antibodies to wolframin may be related to delayed fixation. Loss of wolframin function in RGCs and the unmyelinated portion of retinal axons could explain optic nerve atrophy in Wolfram Syndrome 1.
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Current World Literature. Curr Opin Nephrol Hypertens 2009; 18:91-3. [DOI: 10.1097/mnh.0b013e32831fd875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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The aged retinal pigment epithelium/choroid: a potential substratum for the pathogenesis of age-related macular degeneration. PLoS One 2008; 3:e2339. [PMID: 18523633 PMCID: PMC2394659 DOI: 10.1371/journal.pone.0002339] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Accepted: 04/24/2008] [Indexed: 11/24/2022] Open
Abstract
Background Although the statement that age is the greatest risk factor for Age-related macular degeneration (AMD) is widely accepted, the cellular and molecular explanations for that clinical statement are not generally known. A major focus of AMD research is the retinal pigment epithelium (RPE)/choroid. The purpose of this study was to characterize the changes in the RPE/choroid with age that may provide a background for the development of AMD. Methodology/Principal Findings We compared the transcriptional profiles, key protein levels and histology of the RPE/choroid from young and old mice. Using three statistical methods, microarray data demonstrated marked changes in the old mouse. There were 315 genes differentially expressed with age; most of these genes were related to immune responses and inflammatory activity. Canonical pathways having significant numbers of upregulated genes in aged RPE/choroid included leukocyte extravasation, complement cascades, natural killer cell signaling and IL-10 signaling. By contrast, the adjacent neural retina showed completely different age-related changes. The levels of proteins that participate in leukocyte extravasation and complement pathways were consistently increased in the normal, aged RPE/choroid. Furthermore, there was increased gene expression and protein levels of leukocyte attracting signal, chemokine ligand 2 (Ccl2) in aged RPE/choroid. In old animals, there was marked extravasation and accumulation of leukocytes from the choroidal circulation onto Bruch's membrane and into the RPE. Conclusions/Significance These phenotypic changes indicate that the RPE/choroid in the normal, old mouse has become an immunologically active tissue. There are signals from the normal, aged RPE/choroid which recruit leukocytes from the circulation and activate the complement cascade. These age-related changes that occur in the RPE/choroid with age, to the extent that they occur in the human retina, may provide the background for an error in regulation of immunological activity to cause AMD to appear in an elderly individual.
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