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Alfaar AS, Stürzbecher L, Diedrichs-Möhring M, Lam M, Roubeix C, Ritter J, Schumann K, Annamalai B, Pompös IM, Rohrer B, Sennlaub F, Reichhart N, Wildner G, Strauß O. FoxP3 expression by retinal pigment epithelial cells: transcription factor with potential relevance for the pathology of age-related macular degeneration. J Neuroinflammation 2022; 19:260. [PMID: 36273134 PMCID: PMC9588251 DOI: 10.1186/s12974-022-02620-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 10/09/2022] [Indexed: 11/15/2022] Open
Abstract
Background Forkhead-Box-Protein P3 (FoxP3) is a transcription factor and marker of regulatory T cells, converting naive T cells into Tregs that can downregulate the effector function of other T cells. We previously detected the expression of FoxP3 in retinal pigment epithelial (RPE) cells, forming the outer blood–retina barrier of the immune privileged eye. Methods We investigated the expression, subcellular localization, and phosphorylation of FoxP3 in RPE cells in vivo and in vitro after treatment with various stressors including age, retinal laser burn, autoimmune inflammation, exposure to cigarette smoke, in addition of IL-1β and mechanical cell monolayer destruction. Eye tissue from humans, mouse models of retinal degeneration and rats, and ARPE-19, a human RPE cell line for in vitro experiments, underwent immunohistochemical, immunofluorescence staining, and PCR or immunoblot analysis to determine the intracellular localization and phosphorylation of FoxP3. Cytokine expression of stressed cultured RPE cells was investigated by multiplex bead analysis. Depletion of the FoxP3 gene was performed with CRISPR/Cas9 editing. Results RPE in vivo displayed increased nuclear FoxP3-expression with increases in age and inflammation, long-term exposure of mice to cigarette smoke, or after laser burn injury. The human RPE cell line ARPE-19 constitutively expressed nuclear FoxP3 under non-confluent culture conditions, representing a regulatory phenotype under chronic stress. Confluently grown cells expressed cytosolic FoxP3 that was translocated to the nucleus after treatment with IL-1β to imitate activated macrophages or after mechanical destruction of the monolayer. Moreover, with depletion of FoxP3, but not of a control gene, by CRISPR/Cas9 gene editing decreased stress resistance of RPE cells. Conclusion Our data suggest that FoxP3 is upregulated by age and under cellular stress and might be important for RPE function. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-022-02620-w.
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Affiliation(s)
- Ahmad Samir Alfaar
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität, Berlin Institute of Health, Humboldt-University, 10117, Berlin, Germany.,Department of Ophthalmology, University Hospital of Ulm, 89075, Ulm, Germany
| | - Lucas Stürzbecher
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität, Berlin Institute of Health, Humboldt-University, 10117, Berlin, Germany
| | - Maria Diedrichs-Möhring
- Section of Immunobiology, Department of Ophthalmology, University Hospital, LMU Munich, 80336, Munich, Germany
| | - Marion Lam
- Institut de La Vision, Sorbonne Université, INSERM, CNRS, 75012, Paris, France
| | - Christophe Roubeix
- Institut de La Vision, Sorbonne Université, INSERM, CNRS, 75012, Paris, France
| | - Julia Ritter
- Institut Für Med. Mikrobiologie, Immunologie Und Hygiene, TU München, 81675, Munich, Germany
| | - Kathrin Schumann
- Institut Für Med. Mikrobiologie, Immunologie Und Hygiene, TU München, 81675, Munich, Germany
| | - Balasubramaniam Annamalai
- Department of Ophthalmology, College of Medicine, Medical University South Carolina, Charleston, SC, 29425, USA
| | - Inga-Marie Pompös
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität, Berlin Institute of Health, Humboldt-University, 10117, Berlin, Germany
| | - Bärbel Rohrer
- Department of Ophthalmology, College of Medicine, Medical University South Carolina, Charleston, SC, 29425, USA
| | - Florian Sennlaub
- Institut de La Vision, Sorbonne Université, INSERM, CNRS, 75012, Paris, France
| | - Nadine Reichhart
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität, Berlin Institute of Health, Humboldt-University, 10117, Berlin, Germany
| | - Gerhild Wildner
- Section of Immunobiology, Department of Ophthalmology, University Hospital, LMU Munich, 80336, Munich, Germany.
| | - Olaf Strauß
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität, Berlin Institute of Health, Humboldt-University, 10117, Berlin, Germany.
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Cipriani V, Tierney A, Griffiths JR, Zuber V, Sergouniotis PI, Yates JRW, Moore AT, Bishop PN, Clark SJ, Unwin RD. Beyond factor H: The impact of genetic-risk variants for age-related macular degeneration on circulating factor-H-like 1 and factor-H-related protein concentrations. Am J Hum Genet 2021; 108:1385-1400. [PMID: 34260948 PMCID: PMC8387294 DOI: 10.1016/j.ajhg.2021.05.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 05/27/2021] [Indexed: 01/04/2023] Open
Abstract
Age-related macular degeneration (AMD) is a leading cause of vision loss; there is strong genetic susceptibility at the complement factor H (CFH) locus. This locus encodes a series of complement regulators: factor H (FH), a splice variant factor-H-like 1 (FHL-1), and five factor-H-related proteins (FHR-1 to FHR-5), all involved in the regulation of complement factor C3b turnover. Little is known about how AMD-associated variants at this locus might influence FHL-1 and FHR protein concentrations. We have used a bespoke targeted mass-spectrometry assay to measure the circulating concentrations of all seven complement regulators and demonstrated elevated concentrations in 352 advanced AMD-affected individuals for all FHR proteins (FHR-1, p = 2.4 × 10-10; FHR-2, p = 6.0 × 10-10; FHR-3, p = 1.5 × 10-5; FHR-4, p = 1.3 × 10-3; FHR-5, p = 1.9 × 10-4) and FHL-1 (p = 4.9 × 10-4) when these individuals were compared to 252 controls, whereas no difference was seen for FH (p = 0.94). Genome-wide association analyses in controls revealed genome-wide-significant signals at the CFH locus for all five FHR proteins, and univariate Mendelian-randomization analyses strongly supported the association of FHR-1, FHR-2, FHR-4, and FHR-5 with AMD susceptibility. These findings provide a strong biochemical explanation for how genetically driven alterations in circulating FHR proteins could be major drivers of AMD and highlight the need for research into FHR protein modulation as a viable therapeutic avenue for AMD.
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Affiliation(s)
- Valentina Cipriani
- William Harvey Research Institute, Queen Mary University of London, London, EC1M 6BQ, United Kingdom; UCL Institute of Ophthalmology, University College London, London, EC1V 9EL, United Kingdom; Moorfields Eye Hospital National Health Service Foundation Trust, London, EC1V 2PD, United Kingdom; UCL Genetics Institute, University College London, London, WC1E 6BT, United Kingdom.
| | - Anna Tierney
- Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine, and Health, The University of Manchester, Manchester, M13 9NY, United Kingdom
| | - John R Griffiths
- Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine, and Health, The University of Manchester, Manchester, M13 9NY, United Kingdom
| | - Verena Zuber
- Department of Epidemiology and Biostatistics, Imperial College London, London, W2 1PG, United Kingdom
| | - Panagiotis I Sergouniotis
- Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine, and Health, University of Manchester, Manchester, M13 9PT, United Kingdom; Manchester Centre for Genomic Medicine, Saint Mary's Hospital, Manchester University National Health Service Foundation Trust, Manchester, M13 9WL, United Kingdom
| | - John R W Yates
- UCL Institute of Ophthalmology, University College London, London, EC1V 9EL, United Kingdom; Moorfields Eye Hospital National Health Service Foundation Trust, London, EC1V 2PD, United Kingdom; Department of Medical Genetics, University of Cambridge, Cambridge, CB2 0QQ, United Kingdom
| | - Anthony T Moore
- UCL Institute of Ophthalmology, University College London, London, EC1V 9EL, United Kingdom; Moorfields Eye Hospital National Health Service Foundation Trust, London, EC1V 2PD, United Kingdom; Ophthalmology Department, University of California San Francisco, San Francisco, CA 94143-0730, USA
| | - Paul N Bishop
- Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine, and Health, University of Manchester, Manchester, M13 9PT, United Kingdom; Manchester Royal Eye Hospital, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, United Kingdom
| | - Simon J Clark
- University Eye Clinic, Department for Ophthalmology, Eberhard Karls University of Tübingen, Tübingen, Baden-Württemberg, 72076, Germany; Institute for Ophthalmic Research, Eberhard Karls University of Tübingen, Tübingen, Baden-Württemberg, 72076, Germany; Lydia Becker Institute of Immunology and Inflammation, Faculty of Biology, Medicine, and Health, University of Manchester, Manchester, M13 9PT, UK
| | - Richard D Unwin
- Stoller Biomarker Discovery Centre and Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine, and Health, The University of Manchester, Manchester, M13 9NQ, United Kingdom.
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de Jong S, Gagliardi G, Garanto A, de Breuk A, Lechanteur YTE, Katti S, van den Heuvel LP, Volokhina EB, den Hollander AI. Implications of genetic variation in the complement system in age-related macular degeneration. Prog Retin Eye Res 2021; 84:100952. [PMID: 33610747 DOI: 10.1016/j.preteyeres.2021.100952] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 02/08/2021] [Accepted: 02/11/2021] [Indexed: 12/23/2022]
Abstract
Age-related macular degeneration (AMD) is the main cause of vision loss among the elderly in the Western world. While AMD is a multifactorial disease, the complement system was identified as one of the main pathways contributing to disease risk. The strong link between the complement system and AMD was demonstrated by genetic associations, and by elevated complement activation in local eye tissue and in the systemic circulation of AMD patients. Several complement inhibitors have been and are being explored in clinical trials, but thus far with limited success, leaving the majority of AMD patients without treatment options to date. This indicates that there is still a gap of knowledge regarding the functional implications of the complement system in AMD pathogenesis and how to bring these towards clinical translation. Many different experimental set-ups and disease models have been used to study complement activation in vivo and in vitro, and recently emerging patient-derived induced pluripotent stem cells and genome-editing techniques open new opportunities to study AMD disease mechanisms and test new therapeutic strategies in the future. In this review we provide an extensive overview of methods employed to understand the molecular processes of complement activation in AMD pathogenesis. We discuss the findings, advantages and challenges of each approach and conclude with an outlook on how recent, exciting developments can fill in current knowledge gaps and can aid in the development of effective complement-targeting therapeutic strategies in AMD.
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Affiliation(s)
- Sarah de Jong
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands
| | - Giuliana Gagliardi
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands
| | - Alejandro Garanto
- Department of Human Genetics, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands; Department of Pediatrics, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands; Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands; Amalia Children's Hospital, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands
| | - Anita de Breuk
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands
| | - Yara T E Lechanteur
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands
| | - Suresh Katti
- Gemini Therapeutics Inc., Cambridge, MA, 02139, USA
| | - Lambert P van den Heuvel
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands; Amalia Children's Hospital, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands; Department of Laboratory Medicine, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands
| | - Elena B Volokhina
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands; Amalia Children's Hospital, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands; Department of Laboratory Medicine, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands
| | - Anneke I den Hollander
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands; Department of Human Genetics, Radboud University Medical Center, 6525, GA, Nijmegen, the Netherlands.
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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: 22] [Impact Index Per Article: 5.5] [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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Tzoumas N, Hallam D, Harris CL, Lako M, Kavanagh D, Steel DHW. Revisiting the role of factor H in age-related macular degeneration: Insights from complement-mediated renal disease and rare genetic variants. Surv Ophthalmol 2020; 66:378-401. [PMID: 33157112 DOI: 10.1016/j.survophthal.2020.10.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 10/27/2020] [Accepted: 10/29/2020] [Indexed: 12/14/2022]
Abstract
Ophthalmologists are long familiar with the eye showing signs of systemic disease, but the association between age-related macular degeneration and abnormal complement activation, common to several renal disorders, has only recently been elucidated. Although complement activation products were identified in drusen almost three decades ago, it was not until the early 21st century that a single-nucleotide polymorphism in the complement factor H gene was identified as a major heritable determinant of age-related macular degeneration, galvanizing global efforts to unravel the pathogenesis of this common disease. Advances in proteomic analyses and familial aggregation studies have revealed distinctive clinical phenotypes segregated by the functional effects of common and rare genetic variants on the mature protein and its splice variant, factor H-like protein 1. The predominance of loss-of-function, N-terminal mutations implicate age-related macular degeneration as a disease of general complement dysregulation, offering several therapeutic avenues for its modulation. Here, we explore the molecular impact of these mutations/polymorphisms on the ability of variant factor H/factor H-like protein 1 to localize to polyanions, pentraxins, proinflammatory triggers, and cell surfaces across ocular and renal tissues and exert its multimodal regulatory functions and their clinical implications. Finally, we critically evaluate key therapeutic and diagnostic efforts in this rapidly evolving field.
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Affiliation(s)
- Nikolaos Tzoumas
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom.
| | - Dean Hallam
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Claire L Harris
- Complement Therapeutics Research Group, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom; National Renal Complement Therapeutics Centre, Royal Victoria Infirmary, Newcastle upon Tyne, United Kingdom
| | - Majlinda Lako
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - David Kavanagh
- Complement Therapeutics Research Group, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom; National Renal Complement Therapeutics Centre, Royal Victoria Infirmary, Newcastle upon Tyne, United Kingdom
| | - David H W Steel
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom; Sunderland Eye Infirmary, Sunderland, United Kingdom
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Schäfer N, Wolf HN, Enzbrenner A, Schikora J, Reichenthaler M, Enzmann V, Pauly D. Properdin Modulates Complement Component Production in Stressed Human Primary Retinal Pigment Epithelium Cells. Antioxidants (Basel) 2020; 9:antiox9090793. [PMID: 32859013 PMCID: PMC7555107 DOI: 10.3390/antiox9090793] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/15/2020] [Accepted: 08/22/2020] [Indexed: 12/16/2022] Open
Abstract
The retinal pigment epithelium (RPE) maintains visual function and preserves structural integrity of the retina. Chronic dysfunction of the RPE is associated with retinal degeneration, including age-related macular degeneration (AMD). The AMD pathogenesis includes both increased oxidative stress and complement dysregulation. Physiological sources of oxidative stress in the retina are well known, while complement sources and regulation are still under debate. Using human primary RPE (hpRPE) cells, we have established a model to investigate complement component expression on transcript and protein level in AMD-risk and non-risk hpRPE cells. We evaluated the effect of properdin, a complement stabilizer, on the hpRPE cell-dependent complement profile exposed to oxidative stress. hpRPE cells expressed complement components, receptors and regulators. Complement proteins were also stored and secreted by hpRPE cells. We associated AMD-risk single nucleotide polymorphisms with an increased secretion of complement factors D (CFD) and I (CFI). Furthermore, we detected hpRPE cell-associated complement activation products (C3a, C5a) independent of any extracellularly added complement system. Exogenous properdin increased the mRNA expression of CFI and CFD, but decreased levels of complement components (C1Q, C3), receptors (C3AR, C5AR1, CD11B) and inflammation-associated transcripts (NLRP3, IL1B) in hpRPE cells exposed to oxidative stress. This properdin effect was time-dependently counter regulated. In conclusion, our data unveiled a local, genotype-associated complement component production in hpRPE cells, regulated by exogenous properdin. The local complement production and activation via blood-independent mechanisms can be a new therapeutic target for AMD.
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Affiliation(s)
- Nicole Schäfer
- Experimental Ophthalmology, Eye clinic, University Hospital Regensburg, 93053 Regensburg, Germany; (N.S.); (H.N.W.); (A.E.); (J.S.); (M.R.)
| | - Hannah N. Wolf
- Experimental Ophthalmology, Eye clinic, University Hospital Regensburg, 93053 Regensburg, Germany; (N.S.); (H.N.W.); (A.E.); (J.S.); (M.R.)
| | - Anne Enzbrenner
- Experimental Ophthalmology, Eye clinic, University Hospital Regensburg, 93053 Regensburg, Germany; (N.S.); (H.N.W.); (A.E.); (J.S.); (M.R.)
| | - Juliane Schikora
- Experimental Ophthalmology, Eye clinic, University Hospital Regensburg, 93053 Regensburg, Germany; (N.S.); (H.N.W.); (A.E.); (J.S.); (M.R.)
| | - Maria Reichenthaler
- Experimental Ophthalmology, Eye clinic, University Hospital Regensburg, 93053 Regensburg, Germany; (N.S.); (H.N.W.); (A.E.); (J.S.); (M.R.)
| | - Volker Enzmann
- Department of Ophthalmology, University Hospital of Bern, University of Bern, 3010 Bern, Switzerland;
- Department of Biomedical Research, University of Bern, 3010 Bern, Switzerland
| | - Diana Pauly
- Experimental Ophthalmology, Eye clinic, University Hospital Regensburg, 93053 Regensburg, Germany; (N.S.); (H.N.W.); (A.E.); (J.S.); (M.R.)
- Correspondence:
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Relationship between Oxidative Stress, Circadian Rhythms, and AMD. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2016:7420637. [PMID: 26885250 PMCID: PMC4738726 DOI: 10.1155/2016/7420637] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 10/24/2015] [Accepted: 10/26/2015] [Indexed: 12/31/2022]
Abstract
This work reviews concepts regarding oxidative stress and the mechanisms by which endogenous and exogenous factors produce reactive oxygen species (ROS). It also surveys the relationships between oxidative stress, circadian rhythms, and retinal damage in humans, particularly those related to light and photodamage. In the first section, the production of ROS by different cell organelles and biomolecules and the antioxidant mechanisms that antagonize this damage are reviewed. The second section includes a brief review of circadian clocks and their relationship with the cellular redox state. In the third part of this work, the relationship between retinal damage and ROS is described. The last part of this work focuses on retinal degenerative pathology, age-related macular degeneration, and the relationships between this pathology, ROS, and light. Finally, the possible interactions between the retinal pigment epithelium (RPE), circadian rhythms, and this pathology are discussed.
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Clark SJ, Schmidt CQ, White AM, Hakobyan S, Morgan BP, Bishop PN. Identification of factor H-like protein 1 as the predominant complement regulator in Bruch's membrane: implications for age-related macular degeneration. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2014; 193:4962-70. [PMID: 25305316 PMCID: PMC4225158 DOI: 10.4049/jimmunol.1401613] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The tight regulation of innate immunity on extracellular matrix (ECM) is a vital part of immune homeostasis throughout the human body, and disruption to this regulation in the eye is thought to contribute directly to the progression of age-related macular degeneration (AMD). The plasma complement regulator factor H (FH) is thought to be the main regulator that protects ECM against damaging complement activation. However, in the present study we demonstrate that a truncated form of FH, called FH-like protein 1 (FHL-1), is the main regulatory protein in the layer of ECM under human retina, called Bruch's membrane. Bruch's membrane is a major site of AMD disease pathogenesis and where drusen, the hallmark lesions of AMD, form. We show that FHL-1 can passively diffuse through Bruch's membrane, whereas the full sized, glycosylated, FH cannot. FHL-1 is largely bound to Bruch's membrane through interactions with heparan sulfate, and we show that the common Y402H polymorphism in the CFH gene, associated with an increased risk of AMD, reduces the binding of FHL-1 to this heparan sulfate. We also show that FHL-1 is retained in drusen whereas FH coats the periphery of the lesions, perhaps inhibiting their clearance. Our results identify a novel mechanism of complement regulation in the human eye, which highlights potential new avenues for therapeutic strategies.
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Affiliation(s)
- Simon J Clark
- Centre for Hearing and Vision Research, Institute of Human Development, University of Manchester, Manchester M13 9PT, United Kingdom; Centre for Advanced Discovery and Experimental Therapeutics, University of Manchester and Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9WL, United Kingdom;
| | - Christoph Q Schmidt
- Institute of Pharmacology of Natural Products and Clinical Pharmacology, Ulm University, 89081 Ulm, Germany
| | - Anne M White
- Centre for Hearing and Vision Research, Institute of Human Development, University of Manchester, Manchester M13 9PT, United Kingdom; Centre for Advanced Discovery and Experimental Therapeutics, University of Manchester and Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9WL, United Kingdom
| | - Svetlana Hakobyan
- Complement Biology Group, Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff CF14 4XN, United Kingdom; and
| | - B Paul Morgan
- Complement Biology Group, Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff CF14 4XN, United Kingdom; and
| | - Paul N Bishop
- Centre for Hearing and Vision Research, Institute of Human Development, University of Manchester, Manchester M13 9PT, United Kingdom; Centre for Advanced Discovery and Experimental Therapeutics, University of Manchester and Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9WL, United Kingdom; Manchester Royal Eye Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester M13 9WL, United Kingdom
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