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Parker MA, Erker LR, Audo I, Choi D, Mohand-Said S, Sestakauskas K, Benoit P, Appelqvist T, Krahmer M, Ségaut-Prévost C, Lujan BJ, Faridi A, Chegarnov EN, Steinkamp PN, Ku C, da Palma MM, Barale PO, Ayelo-Scheer S, Lauer A, Stout T, Wilson DJ, Weleber RG, Pennesi ME, Sahel JA, Yang P. Three-Year Safety Results of SAR422459 (EIAV-ABCA4) Gene Therapy in Patients With ABCA4-Associated Stargardt Disease: An Open-Label Dose-Escalation Phase I/IIa Clinical Trial, Cohorts 1-5. Am J Ophthalmol 2022; 240:285-301. [PMID: 35248547 DOI: 10.1016/j.ajo.2022.02.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 12/10/2021] [Accepted: 02/09/2022] [Indexed: 11/01/2022]
Abstract
PURPOSE To report on the safety of the first 5 cohorts of a gene therapy trial using recombinant equine infectious anemia virus expressing ABCA4 (EIAV-ABCA4) in adults with Stargardt dystrophy due to mutations in ABCA4. DESIGN Nonrandomized multicenter phase I/IIa clinical trial. METHODS Patients received a subretinal injection of EIAVABCA4 in the worse-seeing eye at 3 dose levels and were followed for 3 years after treatment. MAIN OUTCOME MEASURES The primary end point was ocular and systemic adverse events. The secondary end points were best-corrected visual acuity, static perimetry, kinetic perimetry, total field hill of vision, full field electroretinogram, multifocal ERG, color fundus photography, short-wavelength fundus autofluorescence, and spectral domain optical coherence tomography. RESULTS The subretinal injections were well tolerated by all 22 patients across 3 dose levels. There was 1 case of a treatment-related ophthalmic serious adverse event in the form of chronic ocular hypertension. The most common adverse events were associated with the surgical procedure. In 1 patient treated with the highest dose, there was a significant decline in the number of macular flecks as compared with the untreated eye. However, in 6 patients, hypoautofluorescent changes were worse in the treated eye than in the untreated eye. Of these, 1 patient had retinal pigment epithelium atrophy that was characteristic of tissue damage likely associated with bleb induction. No patients had any clinically significant changes in best-corrected visual acuity, static perimetry, kinetic perimetry, total field hill of vision, full field electroretinogram, or multifocal ERG attributable to the treatment. CONCLUSIONS Subretinal treatment with EIAV-ABCA4 was well tolerated with only 1 case of ocular hypertension. No clinically significant changes in visual function tests were found to be attributable to the treatment. However, 27% of treated eyes showed exacerbation of retinal pigment epithelium atrophy on fundus autofluorescence. There was a significant reduction in macular flecks in 1 treated eye from the highest dose cohort. Additional follow-up and continued investigation in more patients will be required to fully characterize the safety and efficacy of EIAV-ABCA4.
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Matynia A, Wang J, Kim S, Li Y, Dimashkie A, Jiang Z, Hu J, Strom SP, Radu RA, Chen R, Gorin MB. Assessing Variant Causality and Severity Using Retinal Pigment Epithelial Cells Derived from Stargardt Disease Patients. Transl Vis Sci Technol 2022; 11:33. [PMID: 35348597 PMCID: PMC8976924 DOI: 10.1167/tvst.11.3.33] [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] [Indexed: 02/06/2023] Open
Abstract
Purpose Modern molecular genetics has revolutionized gene discovery, genetic diagnoses, and precision medicine yet many patients remain unable to benefit from these advances as disease-causing variants remain elusive for up to half of Mendelian genetic disorders. Patient-derived induced pluripotent stem (iPS) cells and transcriptomics were used to identify the fate of unsolved ABCA4 alleles in patients with Stargardt disease. Methods Multiple independent iPS lines were generated from skin biopsies of three patients with Stargardt disease harboring a single identified pathogenic ABCA4 variant. Derived retinal pigment epithelial cells (dRPE) from a normal control and patient cells were subjected to RNA-Seq on the Novaseq6000 platform, analyzed using DESeq2 with calculation of allele specific imbalance from the pathogenic or a known linked variant. Protein analysis was performed using the automated Simple Western system. Results Nine dRPE samples were generated, with transcriptome analysis on eight. Allele-specific expression indicated normal transcripts expressed from splice variants albeit at low levels, and missense transcripts expressed at near-normal levels. Corresponding protein was not easily detected. Patient phenotype correlation indicated missense variants expressed at high levels have more deleterious outcomes. Transcriptome analysis suggests mitochondrial membrane biodynamics and the unfolded protein response pathway may be relevant in Stargardt disease. Conclusions Patient-specific iPS-derived RPE cells set the stage to assess non-expressing variants in difficult-to-detect genomic regions using easily biopsied tissue. Translational Relevance This “Disease in a Dish” approach is likely to enhance the ability of patients to participate in and benefit from clinical trials while providing insights into perturbations in RPE biology.
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Affiliation(s)
- Anna Matynia
- UCLA Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Jun Wang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Sangbae Kim
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Yumei Li
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Anupama Dimashkie
- Eli and Edythe Broad Stem Cell Research Center, University of California, Los Angeles, CA, USA
| | - Zhichun Jiang
- UCLA Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Jane Hu
- UCLA Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | | | - Roxana A Radu
- UCLA Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Rui Chen
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Structural and Computational Biology and Molecular Biophysics Graduate Program, Baylor College of Medicine, Houston, TX, USA
| | - Michael B Gorin
- UCLA Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
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Ekesten B, Mäkeläinen S, Ellis S, Kjellström U, Bergström TF. Abnormal Appearance of the Area Centralis in Labrador Retrievers With an ABCA4 Loss-of-function Mutation. Transl Vis Sci Technol 2022; 11:36. [PMID: 35201338 PMCID: PMC8883171 DOI: 10.1167/tvst.11.2.36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To study retinal appearance and morphology in Labrador retrievers (LRs) heterozygous and homozygous for an ABCA4 loss-of-function mutation. METHODS Ophthalmic examination, including ophthalmoscopy and simple testing of vision, was performed in five ABCA4wt/wt, four ABCA4wt/InsC, and six ABCA4InsC/InsC LRs. Retinas were also examined with confocal scanning laser ophthalmoscopy (cSLO) and optical coherence tomography (OCT). Infrared and fundus autofluorescence (FAF) images were studied, and outer nuclear layer (ONL) and neuroretinal thickness were measured in the central and peripheral area centralis. RESULTS Clinical signs in young ABCA4InsC/InsC LRs were subtle, whereas ophthalmoscopic findings and signs of visual impairment were obvious in old ABCA4InsC/InsC LRs. Retinal appearance and vision testing was unremarkable in heterozygous LRs regardless of age. The cSLO/OCT showed abnormal morphology including ONL thinning, abnormal outer retinal layer segmentation, and focal loss of retinal pigment epithelium in the fovea equivalent in juvenile ABCA4InsC/InsC LRs. The abnormal appearance extended into the area centralis and visual streak in middle-aged ABCA4InsC/InsC and then spread more peripherally. A mild phenotype was seen on cSLO/OCT and FAF in middle-aged to old ABCA4wt/InsC LRs. CONCLUSIONS Abnormal appearance and morphology in the fovea equivalent are present in juvenile ABCA4InsC/InsC. In the older affected LRs, the visual streak and then the peripheral retina also develop an abnormal appearance. Vision deteriorates slowly, but some vision is retained throughout life. Older heterozygotes may show a mild retinal phenotype but no obvious visual impairment. The ABCA4InsC/InsC LR is a potential model for ABCA4-mediated retinopathies/juvenile-onset Stargardt disease in a species with human-sized eyes. TRANSLATIONAL RELEVANCE The ABCA4InsC mutation causes juvenile-onset abnormal appearance of the fovea equivalent in affected dogs that slowly spreads in the retina, while only a mild phenotype is seen in older carriers. This is the first non-primate, large-animal model for ABCA4-related/STGD1 retinopathies in a species with a fovea equivalent.
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Affiliation(s)
- Björn Ekesten
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Suvi Mäkeläinen
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.,Department of Medical Biochemistry and Microbiology, Comparative Genetics and Functional Genomics, Uppsala University, Uppsala, Sweden
| | | | | | - Tomas F Bergström
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
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The Role of Vitamin A in Retinal Diseases. Int J Mol Sci 2022; 23:ijms23031014. [PMID: 35162940 PMCID: PMC8835581 DOI: 10.3390/ijms23031014] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 01/12/2022] [Accepted: 01/13/2022] [Indexed: 12/24/2022] Open
Abstract
Vitamin A is an essential fat-soluble vitamin that occurs in various chemical forms. It is essential for several physiological processes. Either hyper- or hypovitaminosis can be harmful. One of the most important vitamin A functions is its involvement in visual phototransduction, where it serves as the crucial part of photopigment, the first molecule in the process of transforming photons of light into electrical signals. In this process, large quantities of vitamin A in the form of 11-cis-retinal are being isomerized to all-trans-retinal and then quickly recycled back to 11-cis-retinal. Complex machinery of transporters and enzymes is involved in this process (i.e., the visual cycle). Any fault in the machinery may not only reduce the efficiency of visual detection but also cause the accumulation of toxic chemicals in the retina. This review provides a comprehensive overview of diseases that are directly or indirectly connected with vitamin A pathways in the retina. It includes the pathophysiological background and clinical presentation of each disease and summarizes the already existing therapeutic and prospective interventions.
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Molday RS, Garces FA, Scortecci JF, Molday LL. Structure and function of ABCA4 and its role in the visual cycle and Stargardt macular degeneration. Prog Retin Eye Res 2021; 89:101036. [PMID: 34954332 DOI: 10.1016/j.preteyeres.2021.101036] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 12/07/2021] [Accepted: 12/13/2021] [Indexed: 12/17/2022]
Abstract
ABCA4 is a member of the superfamily of ATP-binding cassette (ABC) transporters that is preferentially localized along the rim region of rod and cone photoreceptor outer segment disc membranes. It uses the energy from ATP binding and hydrolysis to transport N-retinylidene-phosphatidylethanolamine (N-Ret-PE), the Schiff base adduct of retinal and phosphatidylethanolamine, from the lumen to the cytoplasmic leaflet of disc membranes. This ensures that all-trans-retinal and excess 11-cis-retinal are efficiently cleared from photoreceptor cells thereby preventing the accumulation of toxic retinoid compounds. Loss-of-function mutations in the gene encoding ABCA4 cause autosomal recessive Stargardt macular degeneration, also known as Stargardt disease (STGD1), and related autosomal recessive retinopathies characterized by impaired central vision and an accumulation of lipofuscin and bis-retinoid compounds. High resolution structures of ABCA4 in its substrate and nucleotide free state and containing bound N-Ret-PE or ATP have been determined by cryo-electron microscopy providing insight into the molecular architecture of ABCA4 and mechanisms underlying substrate recognition and conformational changes induced by ATP binding. The expression and functional characterization of a large number of disease-causing missense ABCA4 variants have been determined. These studies have shed light into the molecular mechanisms underlying Stargardt disease and a classification that reliably predicts the effect of a specific missense mutation on the severity of the disease. They also provide a framework for developing rational therapeutic treatments for ABCA4-associated diseases.
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Affiliation(s)
- Robert S Molday
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, B.C., Canada; Department of Ophthalmology & Visual Sciences, University of British Columbia, Vancouver, B.C., Canada.
| | - Fabian A Garces
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, B.C., Canada
| | | | - Laurie L Molday
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, B.C., Canada
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Lipofuscin causes atypical necroptosis through lysosomal membrane permeabilization. Proc Natl Acad Sci U S A 2021; 118:2100122118. [PMID: 34782457 DOI: 10.1073/pnas.2100122118] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/22/2021] [Indexed: 01/16/2023] Open
Abstract
Lipofuscin granules enclose mixtures of cross-linked proteins and lipids in proportions that depend on the tissue analyzed. Retinal lipofuscin is unique in that it contains mostly lipids with very little proteins. However, retinal lipofuscin also presents biological and physicochemical characteristics indistinguishable from conventional granules, including indigestibility, tendency to cause lysosome swelling that results in rupture or defective functions, and ability to trigger NLRP3 inflammation, a symptom of low-level disruption of lysosomes. In addition, like conventional lipofuscins, it appears as an autofluorescent pigment, considered toxic waste, and a biomarker of aging. Ocular lipofuscin accumulates in the retinal pigment epithelium (RPE), whereby it interferes with the support of the neuroretina. RPE cell death is the primary cause of blindness in the most prevalent incurable genetic and age-related human disorders, Stargardt disease and age-related macular degeneration (AMD), respectively. Although retinal lipofuscin is directly linked to the cell death of the RPE in Stargardt, the extent to which it contributes to AMD is a matter of debate. Nonetheless, the number of AMD clinical trials that target lipofuscin formation speaks for the potential relevance for AMD as well. Here, we show that retinal lipofuscin triggers an atypical necroptotic cascade, amenable to pharmacological intervention. This pathway is distinct from canonic necroptosis and is instead dependent on the destabilization of lysosomes. We also provide evidence that necroptosis is activated in aged human retinas with AMD. Overall, this cytotoxicity mechanism may offer therapeutic targets and markers for genetic and age-related diseases associated with lipofuscin buildups.
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Qiu Y, Li H, Xie J, Qiao X, Wu J. Identification of ABCC5 Among ATP-Binding Cassette Transporter Family as a New Biomarker for Hepatocellular Carcinoma Based on Bioinformatics Analysis. Int J Gen Med 2021; 14:7235-7246. [PMID: 34737618 PMCID: PMC8560065 DOI: 10.2147/ijgm.s333904] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 09/29/2021] [Indexed: 12/25/2022] Open
Abstract
Purpose Liver cancer is the fifth most common type of cancer worldwide, and the ATP-binding cassette (ABC) transporter family has been widely accepted as a cause of multidrug resistance. This study was conducted to explore the potential value and mechanisms of the ABC transporter gene family in the liver hepatocellular carcinoma (LIHC). Materials and Methods Data were collected from different public databases. UALCAN, ONCOMINE, and GEPIA were used to retrieve a selection of differently expressed and pathological stage-related genes among the ABC family. Principal component analysis (PCA) was utilized for grouping, and its prognostic value was evaluated by univariate and multivariate Cox analyses. The co-expression pattern was constructed with UALCAN, and the functional analyses were carried out with DAVID. The correlation between the biomarker and immune infiltration, genetic alteration frequency, and drug sensitivity were explored with TIMER, cBioPortal, GDSC and CTRP, respectively. Finally, tSNE algorithm was used to explore the distribution of ABCC5 expressed cells. Results Among the ABC transporter family members, ABCC5 was differently expressed and strongly related to the pathological stage of LIHC. PCA divided patients of LIHC into two groups, and Cox analyses demonstrated that ABCC5 was an independent risk factor of LIHC. Functional analyses indicated that the genes were enriched in the pathways of transmembrane transporter, ATPase activity, and bile secretion. ABCC5 is also associated with immune infiltration of cells like macrophages, neutrophils, and dendritic cells. The genetic alteration frequency of ABCC5 confirmed its potential value in LIHC. In addition, several drugs were explored and found to be relevant to LIHC. The t-SNE showed that expression of ABCC5 was most concentrated in macrophages, followed by hepatocytes. Conclusion ABCC5 may facilitate LIHC progression through different mechanisms and be a potential biomarker and target for diagnosis, prognosis, and therapy of LIHC.
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Affiliation(s)
- Yuting Qiu
- Department of Gastroenterology, Beijing Friendship Hospital, Capital Medical University, National Clinical Research Centre for Digestive Diseases, Beijing, 100050, People's Republic of China
| | - Haobo Li
- Department of Pulmonary and Critical Care Medicine, China-Japan Friendship Hospital; Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100029, People's Republic of China
| | - Jiaheng Xie
- Department of Burn and Plastic Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, 210029, People's Republic of China
| | - Xinwei Qiao
- Department of Gastroenterology, Beijing Friendship Hospital, Capital Medical University, National Clinical Research Centre for Digestive Diseases, Beijing, 100050, People's Republic of China
| | - Jing Wu
- Department of Gastroenterology, Beijing Friendship Hospital, Capital Medical University, National Clinical Research Centre for Digestive Diseases, Beijing, 100050, People's Republic of China
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59
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A genomewide association study on individuals with occludable angles identifies potential risk loci for intraocular pressure. J Genet 2021. [DOI: 10.1007/s12041-021-01321-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Huang D, Heath Jeffery RC, Aung-Htut MT, McLenachan S, Fletcher S, Wilton SD, Chen FK. Stargardt disease and progress in therapeutic strategies. Ophthalmic Genet 2021; 43:1-26. [PMID: 34455905 DOI: 10.1080/13816810.2021.1966053] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Background: Stargardt disease (STGD1) is an autosomal recessive retinal dystrophy due to mutations in ABCA4, characterized by subretinal deposition of lipofuscin-like substances and bilateral centrifugal vision loss. Despite the tremendous progress made in the understanding of STGD1, there are no approved treatments to date. This review examines the challenges in the development of an effective STGD1 therapy.Materials and Methods: A literature review was performed through to June 2021 summarizing the spectrum of retinal phenotypes in STGD1, the molecular biology of ABCA4 protein, the in vivo and in vitro models used to investigate the mechanisms of ABCA4 mutations and current clinical trials.Results: STGD1 phenotypic variability remains an challenge for clinical trial design and patient selection. Pre-clinical development of therapeutic options has been limited by the lack of animal models reflecting the diverse phenotypic spectrum of STDG1. Patient-derived cell lines have facilitated the characterization of splice mutations but the clinical presentation is not always predicted by the effect of specific mutations on retinoid metabolism in cellular models. Current therapies primarily aim to delay vision loss whilst strategies to restore vision are less well developed.Conclusions: STGD1 therapy development can be accelerated by a deeper understanding of genotype-phenotype correlations.
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Affiliation(s)
- Di Huang
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Western Australia, Australia.,Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), the University of Western Australia, Nedlands, Western Australia, Australia.,Perron Institute for Neurological and Translational Science & the University of Western Australia, Nedlands, Western Australia, Australia
| | - Rachael C Heath Jeffery
- Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), the University of Western Australia, Nedlands, Western Australia, Australia
| | - May Thandar Aung-Htut
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Western Australia, Australia.,Perron Institute for Neurological and Translational Science & the University of Western Australia, Nedlands, Western Australia, Australia
| | - Samuel McLenachan
- Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), the University of Western Australia, Nedlands, Western Australia, Australia
| | - Sue Fletcher
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Western Australia, Australia.,Perron Institute for Neurological and Translational Science & the University of Western Australia, Nedlands, Western Australia, Australia
| | - Steve D Wilton
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Western Australia, Australia.,Perron Institute for Neurological and Translational Science & the University of Western Australia, Nedlands, Western Australia, Australia
| | - Fred K Chen
- Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), the University of Western Australia, Nedlands, Western Australia, Australia.,Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia.,Department of Ophthalmology, Royal Perth Hospital, Perth, Western Australia, Australia.,Department of Ophthalmology, Perth Children's Hospital, Nedlands, Western Australia, Australia
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Meleppat RK, Ronning KE, Karlen SJ, Burns ME, Pugh EN, Zawadzki RJ. In vivo multimodal retinal imaging of disease-related pigmentary changes in retinal pigment epithelium. Sci Rep 2021; 11:16252. [PMID: 34376700 PMCID: PMC8355111 DOI: 10.1038/s41598-021-95320-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 07/20/2021] [Indexed: 02/08/2023] Open
Abstract
Melanosomes, lipofuscin, and melanolipofuscin are the three principal types of pigmented granules found in retinal pigment epithelium (RPE) cells. Changes in the density of melanosomes and lipofuscin in RPE cells are considered hallmarks of various retinal diseases, including Stargardt disease and age-related macular degeneration (AMD). Herein, we report the potential of an in vivo multimodal imaging technique based on directional back-scattering and short-wavelength fundus autofluorescence (SW-FAF) to study disease-related changes in the density of melanosomes and lipofuscin granules in RPE cells. Changes in the concentration of these granules in Abca4-/- mice (a model of Stargardt disease) relative to age-matched wild-type (WT) controls were investigated. Directional optical coherence tomography (dOCT) was used to assess melanosome density in vivo, whereas the autofluorescence (AF) images and emission spectra acquired with a spectrometer-integrated scanning laser ophthalmoscope (SLO) were used to characterize lipofuscin and melanolipofuscin granules in the same RPE region. Subcellular-resolution ex vivo imaging using confocal fluorescence microscopy and electron microscopy was performed on the same tissue region to visualize and quantify melanosomes, lipofuscin, and melanolipofuscin granules. Comparisons between in vivo and ex vivo results confirmed an increased concentration of lipofuscin granules and decreased concentration of melanosomes in the RPE of Abca4-/- mice, and provided an explanation for the differences in fluorescence and directionality of RPE scattering observed in vivo between the two mouse strains.
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Affiliation(s)
- Ratheesh K Meleppat
- UC Davis Eyepod Imaging Laboratory, University of California Davis, Davis, CA, 95616, USA
- Department of Cell Biology and Human Anatomy, University of California Davis, Davis, CA, 95616, USA
- Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA, USA
| | - Kaitryn E Ronning
- Center for Neuroscience, University of California Davis, Davis, CA, 95618, USA
| | - Sarah J Karlen
- Department of Cell Biology and Human Anatomy, University of California Davis, Davis, CA, 95616, USA
| | - Marie E Burns
- Center for Neuroscience, University of California Davis, Davis, CA, 95618, USA
- Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA, USA
| | - Edward N Pugh
- UC Davis Eyepod Imaging Laboratory, University of California Davis, Davis, CA, 95616, USA
- Department of Cell Biology and Human Anatomy, University of California Davis, Davis, CA, 95616, USA
| | - Robert J Zawadzki
- UC Davis Eyepod Imaging Laboratory, University of California Davis, Davis, CA, 95616, USA.
- Department of Cell Biology and Human Anatomy, University of California Davis, Davis, CA, 95616, USA.
- Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA, USA.
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Holtan JP, Aukrust I, Jansson RW, Berland S, Bruland O, Gjerde BL, Stokowy T, Bojovic O, Forsaa V, Austeng D, Rødahl E, Bredrup C, Knappskog PM, Bragadóttir R. Clinical features and molecular genetics of patients with ABCA4-retinal dystrophies. Acta Ophthalmol 2021; 99:e733-e746. [PMID: 33258285 DOI: 10.1111/aos.14679] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 09/29/2020] [Accepted: 10/17/2020] [Indexed: 02/06/2023]
Abstract
PURPOSE Pathogenic variations in the ABCA4 gene are a leading cause of vision loss in patients with inherited retinal diseases. ABCA4-retinal dystrophies are clinically heterogeneous, presenting with mild to severe degeneration of the retina. The purpose of this study was to clinically and genetically characterize patients with ABCA4-retinal dystrophies in Norway and describe phenotype-genotype associations. METHODS ABCA4 variants were detected in 111 patients with inherited retinal disease undergoing diagnostic genetic testing over a period of 12 years. In patients where only a single ABCA4 variant was found, whole-gene ABCA4 sequencing was performed and intronic variants were investigated by mRNA analyses in fibroblasts. Medical journals were used to obtain a clinical description and ultrawidefield autofluorescence images were used to analyse retinal degeneration patterns. RESULTS The genetic diagnostic yield was 89%. The intronic splice variant c.5461-10T>C was the most prevalent disease-causing variant (27%). Whole-gene ABCA4 sequencing detected two novel intronic variants (c.6729+81G>T and c.6817-679C>A) that we showed affected mRNA splicing. Peripheral retinal degeneration was identified in 33% of patients and was associated with genotypes that included severe loss of function variants. By contrast, peripheral degeneration was not found in patients with a disease duration over 20 years and genotypes including p.(Asn1868lle), c.4253+43G>A or p.(Gly1961Glu) in trans with a loss of function variant. CONCLUSION This study demonstrates the clinical and genetic heterogeneity of ABCA4-retinal dystrophies in Norway. Further, the study presents novel variants and increases our knowledge on phenotype-genotype associations and the presence of peripheral retinal degeneration in ABCA4-retinal dystrophy patients.
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Affiliation(s)
- Josephine Prener Holtan
- Department of Ophthalmology Oslo University Hospital Oslo Norway
- Institute of Clinical Medicine University of Oslo Oslo Norway
| | - Ingvild Aukrust
- Department of Medical Genetics Haukeland University Hospital Bergen Norway
- Department of Clinical Science University of Bergen Bergen Norway
| | | | - Siren Berland
- Department of Medical Genetics Haukeland University Hospital Bergen Norway
| | - Ove Bruland
- Department of Medical Genetics Haukeland University Hospital Bergen Norway
| | | | - Tomasz Stokowy
- Genomics Core Facility Department of Clinical Science University of Bergen Bergen Norway
| | - Ognjen Bojovic
- Department of Medical Genetics Haukeland University Hospital Bergen Norway
| | - Vegard Forsaa
- Department of Ophthalmology Stavanger University Hospital Stavanger Norway
| | - Dordi Austeng
- Department of Ophthalmology St. Olav University Hospital Trondheim Norway
| | - Eyvind Rødahl
- Department of Ophthalmology Haukeland University Hospital Bergen Norway
- Department of Clinical Medicine University of Bergen Bergen Norway
| | - Cecilie Bredrup
- Department of Ophthalmology Haukeland University Hospital Bergen Norway
- Department of Clinical Medicine University of Bergen Bergen Norway
| | - Per Morten Knappskog
- Department of Medical Genetics Haukeland University Hospital Bergen Norway
- Department of Clinical Science University of Bergen Bergen Norway
| | - Ragnheiður Bragadóttir
- Department of Ophthalmology Oslo University Hospital Oslo Norway
- Institute of Clinical Medicine University of Oslo Oslo Norway
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Boyer NP, Thompson DA, Koutalos Y. Relative Contributions of All-Trans and 11-Cis Retinal to Formation of Lipofuscin and A2E Accumulating in Mouse Retinal Pigment Epithelium. Invest Ophthalmol Vis Sci 2021; 62:1. [PMID: 33523199 PMCID: PMC7862733 DOI: 10.1167/iovs.62.2.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Bis-retinoids are a major component of lipofuscin that accumulates in the retinal pigment epithelium (RPE) in aging and age-related macular degeneration (AMD). Although bis-retinoids are known to originate from retinaldehydes required for the light response of photoreceptor cells, the relative contributions of the chromophore, 11-cis retinal, and photoisomerization product, all-trans retinal, are unknown. In photoreceptor outer segments, all-trans retinal, but not 11-cis retinal, is reduced by retinol dehydrogenase 8 (RDH8). Using Rdh8−/− mice, we evaluated the contribution of increased all-trans retinal to the formation and stability of RPE lipofuscin. Methods Rdh8−/− mice were reared in cyclic-light or darkness for up to 6 months, with selected light-reared cohorts switched to dark-rearing for the final 1 to 8 weeks. The bis-retinoid A2E was measured from chloroform-methanol extracts of RPE-choroid using HPLC-UV/VIS spectroscopy. Lipofuscin fluorescence was measured from whole flattened eyecups (excitation, 488 nm; emission, 565–725 nm). Results Cyclic-light-reared Rdh8−/− mice accumulated A2E and RPE lipofuscin approximately 1.5 times and approximately 2 times faster, respectively, than dark-reared mice. Moving Rdh8−/− mice from cyclic-light to darkness resulted in A2E levels less than expected to have accumulated before the move. Conclusions Our findings establish that elevated levels of all-trans retinal present in cyclic-light-reared Rdh8−/− mice, which remain low in wild-type mice, contribute only modestly to RPE lipofuscin formation and accumulation. Furthermore, decreases in A2E levels occurring after moving cyclic-light-reared Rdh8−/− mice to darkness are consistent with processing of A2E within the RPE and the existence of a mechanism that could be a therapeutic target for controlling A2E cytotoxicity.
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Affiliation(s)
- Nicholas P Boyer
- Department of Ophthalmology, Medical University of South Carolina, Charleston, South Carolina, United States
| | - Debra A Thompson
- Department of Ophthalmology, University of Michigan School of Medicine, Ann Arbor, Michigan, United States.,Department of Biological Chemistry, University of Michigan School of Medicine, Ann Arbor, Michigan, United States
| | - Yiannis Koutalos
- Department of Ophthalmology, Medical University of South Carolina, Charleston, South Carolina, United States
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Dhooge PPA, Runhart EH, Lambertus S, Bax NM, Groenewoud JMM, Klevering BJ, Hoyng CB. Correlation of Morphology and Function of Flecks Using Short-Wave Fundus Autofluorescence and Microperimetry in Patients With Stargardt Disease. Transl Vis Sci Technol 2021; 10:18. [PMID: 34003952 PMCID: PMC7991959 DOI: 10.1167/tvst.10.3.18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Purpose The purpose of this study was to evaluate the functional relevance of longitudinal changes in hyperautofluorescent areas and flecks in Stargardt disease (STGD1) using short-wavelength autofluorescence (SW-AF) imaging. Methods In this prospective, longitudinal study, 31 patients with STGD1 (56 eyes) underwent microperimetry (MP) and SW-AF imaging twice in 3 to 5 years. A total of 760 MP test points were included in the statistical analysis based on stable fixation and accurate alignment of SW-AF and MP. Autofluorescence intensity was qualitatively assessed in all MP test points. Small circumscriptive hyperautofluorescent lesions were defined as flecks. Longitudinal imaging characteristics observed on SW-AF were classified into the following categories: appearing, disappearing, and stable flecks, stable hyperautofluorescent, and stable background autofluorescence. The relationship between SW-AF intensity changes and MP changes was analyzed using a linear mixed model corrected for baseline sensitivity. Results Retinal sensitivity declined most in locations without change in SW-AF intensity. Functional decline per year was significantly larger in flecks that disappeared (−0.72 ± 1.30 dB) compared to flecks that appeared (−0.34 ± 0.65 dB), if baseline sensitivity was high (≥10 dB; P < 0.01). The correlation between the change observed on SW-AF and the sensitivity change significantly depended on the sensitivity at baseline (P = 0.000). Conclusions Qualitative longitudinal assessment of SW-AF poorly reflected the retinal sensitivity loss observed over the course of 3 to 5 years. Translational Relevance When aiming to assess treatment effect on lesion level, a multimodal end point including MP focused on hyperautofluorescent lesions appears essential but needs further studies on optimizing MP grids, eye-tracking systems, and alignment software.
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Affiliation(s)
- Patty P A Dhooge
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Esmee H Runhart
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Stanley Lambertus
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Nathalie M Bax
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Johannes M M Groenewoud
- Department for Health Evidence, Radboud University Medical Center, Nijmegen, The Netherlands
| | - B Jeroen Klevering
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Carel B Hoyng
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
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65
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Dhooge PPA, Runhart EH, Li CHZ, de Kat Angelino CM, Hoyng CB, van der Molen RG, den Hollander AI. Systemic complement activation levels in Stargardt disease. PLoS One 2021; 16:e0253716. [PMID: 34170959 PMCID: PMC8232401 DOI: 10.1371/journal.pone.0253716] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 06/10/2021] [Indexed: 12/16/2022] Open
Abstract
Purpose Preclinical research provides evidence for the complement system as a potential common pathway in Stargardt disease (STGD1) and age-related macular degeneration (AMD) leading to retinal pigment epithelium (RPE) loss. However, systemic complement activation has not yet been assessed in STGD1 patients. We conducted a cross-sectional case-control study to assess systemic complement activation in STGD1 patients and its association with disease severity. Methods Systemic concentrations of complement component C3 and its degradation product C3d were compared between 80 STGD1 patients and 80 controls that were frequency matched for age and sex. The C3d/C3 ratio was used as parameter of systemic complement activation. Within the STGD1 cohort, we additionally examined the association between the C3d/C3 ratio, demographic and behavioural factors (age, sex, smoking and BMI), and measures of disease severity (age at onset, visual acuity, and area of atrophy). Results The C3d/C3 ratio did not significantly differ between patients (mean C3d/C3 ratio 3.5±1.4) and controls (mean C3d/C3 ratio 3.6±1.0), mean difference -0.156 (p = 0.804, independent samples t-test). The overall effect size was 8% (95% confidence interval, 3–15%). Elevated C3d/C3 ratios (>8.1) were found in three patients who all had a concomitant inflammatory condition at the time of blood draw. Within the patient cohort, C3 levels were associated with sex (mean difference -134, p = 0.001, independent samples t-test) and BMI (correlation coefficient 0.463, p<0.001, Spearman’s Correlation). Conclusions Systemic complement levels were not elevated in STGD1 patients compared to age and sex matched controls and was not associated with STGD1 severity. Considering the continued absent proof of a systemic contribution of the complement system to RPE loss in STGD1 patients, we hypothesize that complement activation in STGD1 is more likely a local process. In light of upcoming complement-targeted therapies, further studies are needed that measure complement levels in the eye of STGD1 patients.
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Affiliation(s)
- Patty P. A. Dhooge
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Esmee H. Runhart
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Catherina H. Z. Li
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Corrie M. de Kat Angelino
- Department of Laboratory Medicine, Laboratory of Medical Immunology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Carel B. Hoyng
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Renate G. van der Molen
- Department of Laboratory Medicine, Laboratory of Medical Immunology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Anneke I. den Hollander
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
- * E-mail:
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Cowan CS, Renner M, De Gennaro M, Gross-Scherf B, Goldblum D, Hou Y, Munz M, Rodrigues TM, Krol J, Szikra T, Cuttat R, Waldt A, Papasaikas P, Diggelmann R, Patino-Alvarez CP, Galliker P, Spirig SE, Pavlinic D, Gerber-Hollbach N, Schuierer S, Srdanovic A, Balogh M, Panero R, Kusnyerik A, Szabo A, Stadler MB, Orgül S, Picelli S, Hasler PW, Hierlemann A, Scholl HPN, Roma G, Nigsch F, Roska B. Cell Types of the Human Retina and Its Organoids at Single-Cell Resolution. Cell 2021; 182:1623-1640.e34. [PMID: 32946783 PMCID: PMC7505495 DOI: 10.1016/j.cell.2020.08.013] [Citation(s) in RCA: 309] [Impact Index Per Article: 103.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 06/14/2020] [Accepted: 08/06/2020] [Indexed: 01/05/2023]
Abstract
Human organoids recapitulating the cell-type diversity and function of their target organ are valuable for basic and translational research. We developed light-sensitive human retinal organoids with multiple nuclear and synaptic layers and functional synapses. We sequenced the RNA of 285,441 single cells from these organoids at seven developmental time points and from the periphery, fovea, pigment epithelium and choroid of light-responsive adult human retinas, and performed histochemistry. Cell types in organoids matured in vitro to a stable "developed" state at a rate similar to human retina development in vivo. Transcriptomes of organoid cell types converged toward the transcriptomes of adult peripheral retinal cell types. Expression of disease-associated genes was cell-type-specific in adult retina, and cell-type specificity was retained in organoids. We implicate unexpected cell types in diseases such as macular degeneration. This resource identifies cellular targets for studying disease mechanisms in organoids and for targeted repair in human retinas.
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Affiliation(s)
- Cameron S Cowan
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Magdalena Renner
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland; Novartis Institutes for Biomedical Research, 4056 Basel, Switzerland
| | - Martina De Gennaro
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland
| | - Brigitte Gross-Scherf
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - David Goldblum
- Department of Ophthalmology, University of Basel, 4031 Basel, Switzerland
| | - Yanyan Hou
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland
| | - Martin Munz
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Tiago M Rodrigues
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland
| | - Jacek Krol
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Tamas Szikra
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Rachel Cuttat
- Novartis Institutes for Biomedical Research, 4056 Basel, Switzerland
| | - Annick Waldt
- Novartis Institutes for Biomedical Research, 4056 Basel, Switzerland
| | - Panagiotis Papasaikas
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland; Swiss Institute of Bioinformatics, 4058 Basel, Switzerland
| | - Roland Diggelmann
- Bio Engineering Laboratory, Department of Biosystems Science and Engineering of ETH Zurich, 4058 Basel, Switzerland
| | - Claudia P Patino-Alvarez
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Patricia Galliker
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland
| | - Stefan E Spirig
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland
| | - Dinko Pavlinic
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland
| | | | - Sven Schuierer
- Novartis Institutes for Biomedical Research, 4056 Basel, Switzerland
| | - Aldin Srdanovic
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Marton Balogh
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland
| | - Riccardo Panero
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland
| | - Akos Kusnyerik
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland; Department of Ophthalmology, Semmelweis University, 1085 Budapest, Hungary
| | - Arnold Szabo
- Department of Anatomy, Histology and Embryology, Semmelweis University, 1085 Budapest, Hungary
| | - Michael B Stadler
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland; Swiss Institute of Bioinformatics, 4058 Basel, Switzerland
| | - Selim Orgül
- Department of Ophthalmology, University of Basel, 4031 Basel, Switzerland
| | - Simone Picelli
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland
| | - Pascal W Hasler
- Department of Ophthalmology, University of Basel, 4031 Basel, Switzerland
| | - Andreas Hierlemann
- Bio Engineering Laboratory, Department of Biosystems Science and Engineering of ETH Zurich, 4058 Basel, Switzerland
| | - Hendrik P N Scholl
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland; Department of Ophthalmology, University of Basel, 4031 Basel, Switzerland; Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Guglielmo Roma
- Novartis Institutes for Biomedical Research, 4056 Basel, Switzerland.
| | - Florian Nigsch
- Novartis Institutes for Biomedical Research, 4056 Basel, Switzerland.
| | - Botond Roska
- Institute of Molecular and Clinical Ophthalmology Basel, 4031 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland; Department of Ophthalmology, University of Basel, 4031 Basel, Switzerland.
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67
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Meleppat RK, Ronning KE, Karlen SJ, Kothandath KK, Burns ME, Pugh EN, Zawadzki RJ. In Situ Morphologic and Spectral Characterization of Retinal Pigment Epithelium Organelles in Mice Using Multicolor Confocal Fluorescence Imaging. Invest Ophthalmol Vis Sci 2021; 61:1. [PMID: 33137194 PMCID: PMC7645167 DOI: 10.1167/iovs.61.13.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Purpose To investigate the major organelles of the retinal pigment epithelium (RPE) in wild-type (WT, control) mice and their changes in pigmented Abca4 knockout (Abca4−/−) mice with in situ morphologic, spatial, and spectral characterization of live ex vivo flat-mounted RPE using multicolor confocal fluorescence microscopy (MCFM). Methods In situ imaging of RPE flat-mounts of agouti Abca4−/− (129S4), agouti WT (129S1/SvlmJ) controls, and B6 albino mice (C57BL/6J-Tyrc-Brd) was performed with a Nikon A1 confocal microscope. High-resolution confocal image z-stacks of the RPE cell mosaic were acquired with four different excitation wavelengths (405 nm, 488 nm, 561 nm, and 640 nm). The autofluorescence images of RPE, including voxel-by-voxel emission spectra, were acquired and processed with Nikon NIS-AR Elements software. Results The 3-dimensional multicolor confocal images provided a detailed visualization of the RPE cell mosaic, including its melanosomes and lipofuscin granules, and their varying characteristics in the different mice strains. The autofluorescence spectra, spatial distribution, and morphologic features of melanosomes and lipofuscin granules were measured. Increased numbers of lipofuscin and reduced numbers of melanosomes were observed in the RPE of Abca4−/− mice relative to controls. Conclusions A detailed assessment of the RPE autofluorescent granules and their changes ex vivo was possible with MCFM. For all excitation wavelengths, autofluorescence from the RPE cells was predominantly contributed by lipofuscin granules, while melanosomes were found to be essentially nonfluorescent. The red shift of the emission peak confirmed the presence of multiple chromophores within lipofuscin granules. The elevated autofluorescence levels in Abca4−/− mice correlated well with the increased number of lipofuscin granules.
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Affiliation(s)
- Ratheesh K Meleppat
- UC Davis Eyepod Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, Davis, California, United States.,Department of Ophthalmology & Vision Science, University of California Davis, Davis, California, United States
| | - Kaitryn E Ronning
- Center for Neuroscience, University of California Davis, Davis, California, United States
| | - Sarah J Karlen
- Department of Cell Biology and Human Anatomy, University of California Davis, Davis, California, United States
| | - Karuna K Kothandath
- UC Davis Eyepod Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, Davis, California, United States.,Department of Ophthalmology & Vision Science, University of California Davis, Davis, California, United States
| | - Marie E Burns
- Department of Ophthalmology & Vision Science, University of California Davis, Davis, California, United States.,Center for Neuroscience, University of California Davis, Davis, California, United States.,Department of Cell Biology and Human Anatomy, University of California Davis, Davis, California, United States
| | - Edward N Pugh
- UC Davis Eyepod Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, Davis, California, United States.,Department of Cell Biology and Human Anatomy, University of California Davis, Davis, California, United States
| | - Robert J Zawadzki
- UC Davis Eyepod Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, Davis, California, United States.,Department of Ophthalmology & Vision Science, University of California Davis, Davis, California, United States
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68
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Camp DA, Gemayel MC, Ciulla TA. Understanding the genetic pathology of Stargardt disease: a review of current findings and challenges. Expert Opin Orphan Drugs 2021. [DOI: 10.1080/21678707.2021.1898373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- David A. Camp
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Michael C. Gemayel
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Thomas A. Ciulla
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
- Retina Service, Midwest Eye Institute, Indianapolis, IN, USA
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69
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Zhu Q, Rui X, Li Y, You Y, Sheng XL, Lei B. Identification of Four Novel Variants and Determination of Genotype-Phenotype Correlations for ABCA4 Variants Associated With Inherited Retinal Degenerations. Front Cell Dev Biol 2021; 9:634843. [PMID: 33732702 PMCID: PMC7957020 DOI: 10.3389/fcell.2021.634843] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Accepted: 01/26/2021] [Indexed: 12/21/2022] Open
Abstract
Purpose The purpose of the study is to describe the genetic and clinical features of 17 patients with ABCA4-related inherited retinal degenerations (IRDs) and define the phenotype–genotype correlations. Methods In this multicenter retrospective study, 17 patients from 16 families were enrolled, and ABCA4 gene variants were detected using targeted next-generation sequencing using a custom designed panel for IRDs. Sanger sequencing and co-segregation analysis of the suspected pathogenic variants were performed with the family members. The pathogenicities of variants were evaluated according to the American College of Medical Genetics and Genomics guidelines (ACMG). Protein structure modifications mediated by the variants were studied using bioinformatic analyses. Results The probands were diagnosed with Stargardt disease 1 (7), cone-rod dystrophy type 3 (8), cone dystrophy (1), and retinitis pigmentosa 19 (1). Onset of symptoms occurred between 5 and 27 years of age (median age = 12.4 years). A total of 30 unique ABCA4 suspicious pathogenic variations were observed, including 18 missense mutations, seven frameshift mutations, two nonsense mutations, one canonical splice site mutation, one small in-frame deletion, and one insertion. Four novel ABCA4 variants were identified. Two novel frameshift variants, c.1290dupC (p.W431fs), and c.2967dupT (G990fs), were determined to be pathogenic. A novel missense variant c.G5761T (p.V1921L) was likely pathogenic, and another novel missense c.C170G (p.P57R) variant was of undetermined significance. All ABCA4 variants tested in this study inordinately changed the physico-chemical parameters and structure of protein based on in silico analysis. Conclusion ABCA4-related IRD is genetically and clinically highly heterogeneous. Four novel ABCA4 variants were identified. This study will expand the spectrum of disease-causing variants in ABCA4, which will further facilitate genetic counseling.
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Affiliation(s)
- Qing Zhu
- Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou, China
| | - Xue Rui
- Ningxia Clinical Research Center of Blinding Eye Disease, Ningxia Eye Hospital, People's Hospital of Ningxia Hui Autonomous Region, First Affiliated Hospital of Northwest University for Nationalities, Yinchuan, China
| | - Ya Li
- Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou, China.,Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute and Henan Eye Hospital, Henan Provincial People's Hospital, Zhengzhou, China
| | - Ya You
- Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou, China.,Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute and Henan Eye Hospital, Henan Provincial People's Hospital, Zhengzhou, China
| | - Xun-Lun Sheng
- Ningxia Clinical Research Center of Blinding Eye Disease, Ningxia Eye Hospital, People's Hospital of Ningxia Hui Autonomous Region, First Affiliated Hospital of Northwest University for Nationalities, Yinchuan, China
| | - Bo Lei
- Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou, China.,Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute and Henan Eye Hospital, Henan Provincial People's Hospital, Zhengzhou, China
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70
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Hamano F, Kuribayashi H, Iwagawa T, Tsuhako A, Nagata K, Sagara H, Shimizu T, Shindou H, Watanabe S. Mapping membrane lipids in the developing and adult mouse retina under physiological and pathological conditions using mass spectrometry. J Biol Chem 2021; 296:100303. [PMID: 33465374 PMCID: PMC7949107 DOI: 10.1016/j.jbc.2021.100303] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 01/05/2021] [Accepted: 01/14/2021] [Indexed: 12/31/2022] Open
Abstract
Membrane phospholipids play pivotal roles in various cellular processes, and their levels are tightly regulated. In the retina, phospholipids had been scrutinized because of their distinct composition and requirement in visual transduction. However, how lipid composition changes during retinal development remains unclear. Here, we used liquid chromatography–mass spectrometry (LC-MS) to assess the dynamic changes in the levels of two main glycerophospholipids, phosphatidylcholine (PC) and phosphatidylethanolamine (PE), in the developing mouse retina under physiological and pathological conditions. The total levels of PC and PE increased during retinal development, and individual lipid species exhibited distinct level changes. The amount of very-long-chain PC and PE increased dramatically in the late stages of retinal development. The mRNA levels of Elovl2 and Elovl4, genes encoding enzymes essential for the synthesis of very-long-chain polyunsaturated fatty acids, increased in developing photoreceptors. Cell sorting based on CD73 expression followed by LC-MS revealed distinct changes in PC and PE levels in CD73-positive rod photoreceptors and CD73-negative retinal cells. Finally, using the NaIO3-induced photoreceptor degeneration model, we identified photoreceptor-specific changes in PC and PE levels from 1 day after NaIO3 administration, before the outer segment of photoreceptors displayed morphological impairment. In conclusion, our findings provide insight into the dynamic changes in PC and PE levels in the developing and adult mouse retina under physiological and pathological conditions. Furthermore, we provide evidence that cell sorting followed by LC-MS is a promising approach for investigating the relevance of lipid homeostasis in the function of different retinal cell types.
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Affiliation(s)
- Fumie Hamano
- Department of Lipid Signaling, National Center for Global Health and Medicine, Shinjuku-ku, Tokyo, Japan; Life Sciences Core Facility, Graduate School of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Hiroshi Kuribayashi
- Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan
| | - Toshiro Iwagawa
- Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan
| | - Asano Tsuhako
- Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan
| | - Katsuyuki Nagata
- Department of Lipid Signaling, National Center for Global Health and Medicine, Shinjuku-ku, Tokyo, Japan
| | - Hiroshi Sagara
- Medical Proteomics Laboratory, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan
| | - Takao Shimizu
- Department of Lipid Signaling, National Center for Global Health and Medicine, Shinjuku-ku, Tokyo, Japan
| | - Hideo Shindou
- Department of Lipid Signaling, National Center for Global Health and Medicine, Shinjuku-ku, Tokyo, Japan; Department of Lipid Science, Graduate School of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Sumiko Watanabe
- Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan.
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Al-Khuzaei S, Shah M, Foster CR, Yu J, Broadgate S, Halford S, Downes SM. The role of multimodal imaging and vision function testing in ABCA4-related retinopathies and their relevance to future therapeutic interventions. Ther Adv Ophthalmol 2021; 13:25158414211056384. [PMID: 34988368 PMCID: PMC8721514 DOI: 10.1177/25158414211056384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Accepted: 10/08/2021] [Indexed: 11/16/2022] Open
Abstract
The aim of this review article is to describe the specific features of Stargardt disease and ABCA4 retinopathies (ABCA4R) using multimodal imaging and functional testing and to highlight their relevance to potential therapeutic interventions. Standardised measures of tissue loss, tissue function and rate of change over time using formal structured deep phenotyping in Stargardt disease and ABCA4R are key in diagnosis, and prognosis as well as when selecting cohorts for therapeutic intervention. In addition, a meticulous documentation of natural history will be invaluable in the future to compare treated with untreated retinas. Despite the familiarity with the term Stargardt disease, this eponymous classification alone is unhelpful when evaluating ABCA4R, as the ABCA4 gene is associated with a number of phenotypes, and a range of severity. Multimodal imaging, psychophysical and electrophysiologic measurements are necessary in diagnosing and characterising these differing retinopathies. A wide range of retinal dystrophy phenotypes are seen in association with ABCA4 mutations. In this article, these will be referred to as ABCA4R. These different phenotypes and the existence of phenocopies present a significant challenge to the clinician. Careful phenotypic characterisation coupled with the genotype enables the clinician to provide an accurate diagnosis, associated inheritance pattern and information regarding prognosis and management. This is particularly relevant now for recruiting to therapeutic trials, and in the future when therapies become available. The importance of accurate genotype-phenotype correlation studies cannot be overemphasised. This approach together with segregation studies can be vital in the identification of causal mutations when variants in more than one gene are being considered as possible. In this article, we give an overview of the current imaging, psychophysical and electrophysiological investigations, as well as current therapeutic research trials for retinopathies associated with the ABCA4 gene.
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Affiliation(s)
- Saoud Al-Khuzaei
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Mital Shah
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | | | | | | | - Stephanie Halford
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Susan M. Downes
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Level 6 John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
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72
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Starace V, Battista M, Brambati M, Pederzolli M, Viganò C, Arrigo A, Cicinelli MV, Bandello F, Parodi MB. Genotypic and phenotypic factors influencing the rate of progression in ABCA-4-related Stargardt disease. EXPERT REVIEW OF OPHTHALMOLOGY 2020. [DOI: 10.1080/17469899.2021.1860753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Vincenzo Starace
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Marco Battista
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Maria Brambati
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Matteo Pederzolli
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Chiara Viganò
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Alessandro Arrigo
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Maria Vittoria Cicinelli
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
- School of Medicine, Vita-Salute San Raffaele University, Milan, Italy
| | - Francesco Bandello
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
- School of Medicine, Vita-Salute San Raffaele University, Milan, Italy
| | - Maurizio Battaglia Parodi
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
- School of Medicine, Vita-Salute San Raffaele University, Milan, Italy
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73
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Nagai N, Kawashima H, Toda E, Homma K, Osada H, Guzman NA, Shibata S, Uchiyama Y, Okano H, Tsubota K, Ozawa Y. Renin-angiotensin system impairs macrophage lipid metabolism to promote age-related macular degeneration in mouse models. Commun Biol 2020; 3:767. [PMID: 33299105 PMCID: PMC7725839 DOI: 10.1038/s42003-020-01483-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 11/16/2020] [Indexed: 12/16/2022] Open
Abstract
Metabolic syndrome, a condition involving obesity and hypertension, increases the risk of aging-associated diseases such as age-related macular degeneration (AMD). Here, we demonstrated that high-fat diet (HFD)-fed mice accumulated oxidized low-density lipoprotein (ox-LDL) in macrophages through the renin–angiotensin system (RAS). The ox-LDL-loaded macrophages were responsible for visual impairment in HFD mice along with a disorder of the retinal pigment epithelium (RPE), which is required for photoreceptor outer segment renewal. RAS repressed ELAVL1, which reduced PPARγ, impeding ABCA1 induction to levels that are sufficient to excrete overloaded cholesterol within the macrophages. The ox-LDL-loaded macrophages expressed inflammatory cytokines and attacked the RPE. An antihypertensive drug, angiotensin II type 1 receptor (AT1R) blocker, resolved the decompensation of lipid metabolism in the macrophages and reversed the RPE condition and visual function in HFD mice. AT1R signaling could be a future therapeutic target for macrophage-associated aging diseases, such as AMD. Nagai et al. show that mice fed high-fat diet (HFD) accumulate oxidized low-density lipoprotein in macrophages through the renin–angiotensin system, which impairs visual function. They find that angiotensin II type 1 receptor (AT1R) improves the visual function of HFD mice, suggesting AT1R signaling as a potential therapeutic target for age-related macular degeneration.
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Affiliation(s)
- Norihiro Nagai
- Laboratory of Retinal Cell Biology, Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjukuku, Tokyo, 160-8582, Japan.,Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjukuku, Tokyo, 160-8582, Japan
| | - Hirohiko Kawashima
- Laboratory of Retinal Cell Biology, Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjukuku, Tokyo, 160-8582, Japan.,Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjukuku, Tokyo, 160-8582, Japan
| | - Eriko Toda
- Laboratory of Retinal Cell Biology, Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjukuku, Tokyo, 160-8582, Japan
| | - Kohei Homma
- Laboratory of Retinal Cell Biology, Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjukuku, Tokyo, 160-8582, Japan
| | - Hideto Osada
- Laboratory of Retinal Cell Biology, Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjukuku, Tokyo, 160-8582, Japan
| | - Naymel A Guzman
- Laboratory of Retinal Cell Biology, Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjukuku, Tokyo, 160-8582, Japan.,Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjukuku, Tokyo, 160-8582, Japan
| | - Shinsuke Shibata
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjukuku, Tokyo, 160-8582, Japan
| | - Yasuo Uchiyama
- Department of Cellular and Molecular Neuropathology, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-0033, Japan
| | - Hideyuki Okano
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjukuku, Tokyo, 160-8582, Japan
| | - Kazuo Tsubota
- Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjukuku, Tokyo, 160-8582, Japan
| | - Yoko Ozawa
- Laboratory of Retinal Cell Biology, Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjukuku, Tokyo, 160-8582, Japan. .,Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjukuku, Tokyo, 160-8582, Japan. .,Department of Ophthalmology, St. Luke's International Hospital, 9-1 Akashi-Cho, Chuo-Ku, Tokyo, 104-8560, Japan. .,St. Luke's International University, 9-1 Akashi-Cho, Tokyo, 104-8560, Japan.
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74
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Coussa RG, Binkley EM, Wilkinson ME, Andorf JL, Tucker BA, Mullins RF, Sohn EH, Yannuzzi LA, Stone EM, Han IC. Predominance of hyperopia in autosomal dominant Best vitelliform macular dystrophy. Br J Ophthalmol 2020; 106:522-527. [DOI: 10.1136/bjophthalmol-2020-317763] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 11/05/2020] [Accepted: 11/15/2020] [Indexed: 12/17/2022]
Abstract
Background/AimsPatients with BEST1-associated autosomal dominant Best vitelliform macular dystrophy (AD-BVMD) have been reported to be hyperopic, but the prevalence of refractive error has not been described. This study aimed to characterise the type and degree of refractive error in a large cohort of patients with AD-BVMD compared with an age-similar group with ABCA4-associated Stargardt disease.MethodsThis was a retrospective chart review of consecutive patients with molecularly confirmed AD-BVMD and Stargardt macular dystrophy seen at a single academic centre. Demographic information, including age, gender and genotype were extracted from the chart. The best corrected visual acuity (BCVA), as well as type and degree of refractive error on manifest refraction for each eye on each visit, were recorded and compared.ResultsA total of 178 eyes from 89 patients with AD-BVMD (35 women, 54 men; mean age 36.6 years) and 306 eyes from 153 patients (94 women, 59 men, mean age 30.2 years) with Stargardt disease were included in the study. Mean BCVA was excellent for both AD-BVMD and Stargardt eyes (logMAR 0.23 vs logMAR 0.31, respectively; p=0.55). At initial refraction, 73.0% of AD-BVMD eyes (130/178) were hyperopic, with mean spherical equivalent (SE) +1.38 dioptres (median +0.88) whereas 80.7% of Stargardt eyes (247/306) were myopic, with mean SE of −1.76 dioptres (median −1.19) (p<0.001).ConclusionPatients with AD-BVMD are predominantly hyperopic, whereas those with Stargardt disease are predominantly myopic. The findings provide further evidence of a role for BEST1 in ocular growth and development.
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75
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Evidence of complement dysregulation in outer retina of Stargardt disease donor eyes. Redox Biol 2020; 37:101787. [PMID: 33214125 PMCID: PMC7767765 DOI: 10.1016/j.redox.2020.101787] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 10/30/2020] [Accepted: 11/03/2020] [Indexed: 01/24/2023] Open
Abstract
Stargardt macular degeneration (STGD) is a central blinding disease caused by loss of or dysfunctional ABCA4 transporter in both photoreceptors and retinal pigment epithelial (RPE) cells. Toxic bisretinoid-lipofuscin buildup in the RPE cells is a pathological hallmark of STGD patients and its mouse model, the Abca4-/-. These vitamin A-derived fluorophores have been shown to induce oxidative stress, stimulate complement activity, and cause chronic inflammation of the RPE. In vivo modulation of complement regulatory pathway in the STGD mouse model has partially rescued the STGD phenotype suggesting that complement attack on the RPE is an important etiologic factor in disease pathogenesis. While bisretinoid-dependent complement activation was further evidenced in cultured RPE cells, this pathway has never been investigated directly in the context of RPE from STGD donor eyes. In the current study, we evaluate the complement reactivity in postmortem donor eyes of clinically diagnosed STGD patients. All three STGD donor eyes RPE displayed strong immunoreactivity for an antibody specific to 4-Hydroxynonenal, a lipid peroxidation byproduct. Also, unlike the control eyes, all three STGD donor eyes showed significantly increased membrane attack complex deposition on the RPE cells. In STGD eyes, increased MAC accumulation was mirrored by elevated C3 fragments internalized by the RPE and inversely correlated with the levels of complement factor H, a major complement regulatory protein. Here, we report the first direct evidence of RPE complement dysregulation as a causative factor in developing Stargardt phenotype.
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76
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Hu FY, Gao FJ, Li JK, Xu P, Wang DD, Zhang SH, Wu JH. Novel variants of ABCA4 in Han Chinese families with Stargardt disease. BMC MEDICAL GENETICS 2020; 21:213. [PMID: 33129279 PMCID: PMC7602306 DOI: 10.1186/s12881-020-01152-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 10/19/2020] [Indexed: 12/13/2022]
Abstract
BACKGROUND Stargardt disease (STGD1) is a common recessive hereditary macular dystrophy in early adulthood or childhood, with an estimated prevalence of 1:8000 to 1:10,000. ABCA4 is the causative gene for STGD1. The current study aims at identifying the novel disease-related ABCA4 variants in Han Chinese families with STGD1 using next-generation sequencing (NGS). METHODS In the present study, 12 unrelated Han Chinese families (19 males and 17 females) with STGD1 were tested by panel-based NGS. In order to capture the coding exons and the untranslated regions (UTRs) plus 30 bp of intronic flanking sequences of 792 genes, which were closely associated with usual ophthalmic genetic disease, we designed a customized panel, namely, Target_Eye_792_V2 chip. STGD1 patients were clinically diagnosed by experienced ophthalmologists. All the detected variants were filtered and analyzed through the public databases and in silico programs to assess potential pathogenicity. RESULTS Twenty-one ABCA4 mutant variants were detected in 12 unrelated Han Chinese families with STGD1, containing 14 missense, three splicing, two frameshift, one small deletion, and one nonsense variants. Base on the American College of Medical Genetics (ACMG) guidelines, 8 likely pathogenic and 13 pathogenic variants were determined. The functional consequences of these mutant variants were predicted through in silico programs. Of the 21 mutant variants in ABCA4, two novel coding variants c.3017G > A and c.5167 T > C and one novel null variant c.3051-1G > A were detected in three unrelated probands. CONCLUSIONS By panel-based NGS, 21 ABCA4 variants were confirmed in 12 unrelated Han Chinese families. Among them, 3 novel mutant variants were found, which further expanded the ABCA4 mutation spectrum in STGD1 patients.
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Affiliation(s)
- Fang-Yuan Hu
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Feng-Juan Gao
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Jian-Kang Li
- BGI-Shenzhen, Shenzhen, China
- Department of Computer Science, City University of Hong Kong, Kowloon, Hong Kong
| | - Ping Xu
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Dan-Dan Wang
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Sheng-Hai Zhang
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Ji-Hong Wu
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China.
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China.
- Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China.
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77
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Vesicular ATP-binding cassette transporters in human disease: relevant aspects of their organization for future drug development. FUTURE DRUG DISCOVERY 2020. [DOI: 10.4155/fdd-2020-0025] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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78
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Curtis SB, Molday LL, Garces FA, Molday RS. Functional analysis and classification of homozygous and hypomorphic ABCA4 variants associated with Stargardt macular degeneration. Hum Mutat 2020; 41:1944-1956. [PMID: 32845050 DOI: 10.1002/humu.24100] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/06/2020] [Accepted: 08/24/2020] [Indexed: 12/14/2022]
Abstract
Stargardt macular degeneration (Stargardt disease 1 [STGD1]) is caused by mutations in the gene encoding ABCA4, an ATP-binding cassette protein that transports N-retinylidene-phosphatidylethanolamine (N-Ret-PE) across photoreceptor membranes. Reduced ABCA4 activity results in retinoid accumulation leading to photoreceptor degeneration. The disease onset and severity vary from severe loss in visual acuity in the first decade to mild visual impairment late in life. We determined the effect of 22 disease-causing missense mutations on the expression and ATPase activity of ABCA4 in the absence and presence of N-Ret-PE. Three classes were identified that correlated with the disease onset in homozygous STGD1 individuals: Class 1 exhibited reduced ABCA4 expression and ATPase activity that was not stimulated by N-Ret-PE; individuals homozygous for these variants had an early disease onset (≤13 years); Class 2 showed reduced ATPase activity with limited stimulation by N-Ret-PE; these correlated with moderate disease onset (14-40 years); and Class 3 displayed high expression and ATPase activity that was strongly activated by N-Ret-PE; these were associated with late disease onset (>40 years). On the basis of our results, we introduce a functionality index for gauging the effect of missense mutations on STGD1 severity. Our studies support the mild phenotype exhibited by the p.Gly863Ala, p.Asn1868Ile, and p.Gly863Ala/p.Asn1868Ile variants.
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Affiliation(s)
- Susan B Curtis
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Laurie L Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Fabian A Garces
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Robert S Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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79
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Reinehr S, Buschhorn V, Mueller-Buehl AM, Goldmann T, Grus FH, Wolfrum U, Dick HB, Joachim SC. Occurrence of Retinal Ganglion Cell Loss via Autophagy and Apoptotic Pathways in an Autoimmune Glaucoma Model. Curr Eye Res 2020; 45:1124-1135. [PMID: 31935132 DOI: 10.1080/02713683.2020.1716987] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 01/01/2020] [Accepted: 01/07/2020] [Indexed: 12/17/2022]
Abstract
PURPOSE In glaucoma, an apoptotic death of retinal ganglion cells (RGCs) has been shown. However, little is known about other cell death mechanisms, like autophagy or necrosis. Therefore, we investigated these mechanisms in addition to antibody deposits in an experimental autoimmune glaucoma model. METHODS Rats were immunized with a retinal ganglion cell-layer homogenate (RGA), while controls received sodium chloride. Untreated rats served as natїve group. After seven weeks, retinal cross-sections were stained with antibodies against RGCs (Brn-3a), apoptosis (cleaved caspase 2, cleaved caspase 3 as well as caspase 3, 8, and 9), autophagy (LC3BII and LAMP1), and necrosis (RIPK3) followed by cell counts. Autophagy was additionally visualized via transmission electron microscopy on retinal sections. Antibody deposits were also analyzed. RESULTS We noted a RGC loss after RGA immunization compared to both control groups. Also, significantly more cleaved caspase 2+ RGCs were observed in RGA animals. More caspase 3 and 8 signals were noted in RGA retinas compared to both controls, while no changes were seen in regard to caspase 9. Furthermore, significantly more cleaved caspase 3+ cells were detected in RGA animals. We noted an increase of LC3BII+ and LAMP1+ autophagic cells in the RGA group, while no alterations were seen regarding necrotic RIPK3+ cells. Autophagic vesicles were observed via transmission electron microscopy. IgG staining revealed significant differences between the RGA group and controls concerning IgG deposits in the ganglion cell layer. CONCLUSIONS Due to the novel results from this study, we conclude that IgG antibodies are involved in RGC loss in this model leading to apoptotic and autophagic cell loss. These results could help to develop new therapy strategies for glaucoma patients.
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Affiliation(s)
- Sabrina Reinehr
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum , Bochum, Germany
| | - Verena Buschhorn
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum , Bochum, Germany
| | - Ana M Mueller-Buehl
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum , Bochum, Germany
| | - Tobias Goldmann
- Molecular Cell Biology, Institute of Molecular Physiology, Johannes Gutenberg-University of Mainz , Germany
| | - Franz H Grus
- Experimental Ophthalmology, University Medical Center Mainz , Mainz, Germany
| | - Uwe Wolfrum
- Molecular Cell Biology, Institute of Molecular Physiology, Johannes Gutenberg-University of Mainz , Germany
| | - H Burkhard Dick
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum , Bochum, Germany
| | - Stephanie C Joachim
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum , Bochum, Germany
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80
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Abstract
High-resolution imaging techniques capable of detecting identifiable endogenous fluorophores in the eye along with genetic testing will dramatically improve diagnostic capabilities in the ophthalmology clinic and accelerate the development of new treatments for blinding diseases. Two-photon excitation (TPE)-based imaging overcomes the filtering of ultraviolet light by the lens of the human eye and thus can be utilized to discover defects in vitamin A metabolism during the regeneration of the visual pigments required for the detection of light. Combining TPE with fluorescence lifetime imaging (FLIM) and spectral analyses offers the potential of detecting diseases of the retina at earlier stages before irreversible structural damage has occurred. The main barriers to realizing the benefits of TPE for imaging the human retina arise from concerns about the high light exposure typically needed for informative TPE imaging and the requirement to correlate the ensuing data with different states of health and disease. To overcome these hurdles, we improved TPE efficiency by controlling temporal properties of the excitation light and employed phasor analyses to FLIM and spectral data in mouse models of retinal diseases. Modeling of retinal photodamage revealed that plasma-mediated effects do not play a role and that melanin-related thermal effects are mitigated by reducing pulse repetition frequency. By using noninvasive TPE imaging we identified molecular components of individual granules in the retinal pigment epithelium and present their analytical characteristics.
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81
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Abstract
The visual phototransduction cascade begins with a cis-trans photoisomerization of a retinylidene chromophore associated with the visual pigments of rod and cone photoreceptors. Visual opsins release their all-trans-retinal chromophore following photoactivation, which necessitates the existence of pathways that produce 11-cis-retinal for continued formation of visual pigments and sustained vision. Proteins in the retinal pigment epithelium (RPE), a cell layer adjacent to the photoreceptor outer segments, form the well-established "dark" regeneration pathway known as the classical visual cycle. This pathway is sufficient to maintain continuous rod function and support cone photoreceptors as well although its throughput has to be augmented by additional mechanism(s) to maintain pigment levels in the face of high rates of photon capture. Recent studies indicate that the classical visual cycle works together with light-dependent processes in both the RPE and neural retina to ensure adequate 11-cis-retinal production under natural illuminances that can span ten orders of magnitude. Further elucidation of the interplay between these complementary systems is fundamental to understanding how cone-mediated vision is sustained in vivo. Here, we describe recent advances in understanding how 11-cis-retinal is synthesized via light-dependent mechanisms.
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82
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Novel Mechanism of Cholesterol Transport by ABCA5 in Macrophages and Its Role in Dyslipidemia. J Mol Biol 2020; 432:4922-4941. [DOI: 10.1016/j.jmb.2020.07.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 07/02/2020] [Accepted: 07/10/2020] [Indexed: 01/24/2023]
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83
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Abstract
In Stargardt disease, retinal fluorescence lifetimes can be used to analyze hyperfluorescent flecks and hypofluorescent atrophic lesions. This study establishes that autofluorescence lifetime demonstrates explicit, reproducible patterns and confirms the diagnostic value of fluorescence lifetime imaging ophthalmoscopy as a noninvasive imaging modality. Supplemental Digital Content is Available in the Text. Purpose: Stargardt disease is the most common inherited juvenile macular dystrophy and is characterized by yellowish flecks across the posterior pole. The purpose of this study was to investigate fluorescence lifetime changes of retinal flecks over time using fluorescence lifetime imaging ophthalmoscopy. Methods: Longitudinal fluorescence lifetime data of 12 patients with Stargardt disease (mean age ± SEM, 42.25 ± 2.1 years; range, 28–58 years) were acquired using a fluorescence lifetime imaging ophthalmoscope based on a Heidelberg Engineering Spectralis system. Retinal autofluorescence was excited with a 470-nm laser. The emitted fluorescence was detected in two wavelength channels: a short spectral channel (498–560 nm) and a long spectral channel (560–720 nm). The mean retinal autofluorescence lifetimes were calculated and further analyzed with corresponding color fundus images, autofluorescence intensity images, and spectral domain optical coherence tomography. Patients were classified into three subtypes. Results: All patients with Stargardt disease displayed characteristic autofluorescence lifetime patterns. Mean fluorescence lifetime values within areas of yellow flecks were significantly prolonged (long spectral channel 484 ps) compared with the surrounding tissue (long spectral channel 297 ps). In 91.6% of the eyes, flecks with short fluorescence lifetimes (long spectral channel 255 ps) were identified. Short lifetime flecks progressed to flecks with characteristic long lifetimes in 75.1% of eyes within a mean interval of 29.2 months (range 3–45 months). Between baseline and follow-up, the rate of newly developed short lifetime flecks (number/per year) based on subtypes was 2.62 in Group 1, 1.43 in Group 2, and 0.81 in Group 3. Conclusion: Recent onset flecks in Stargardt disease display short fluorescence lifetimes and convert into longer fluorescence lifetime flecks over time. This transition may represent a change in the composition of retinal deposits with accumulation of lipofuscin and retinoid by-products from the visual cycle. With emerging treatment options, these findings may prove useful to monitor disease progression and therapeutic effects.
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84
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Palfi A, Yesmambetov A, Humphries P, Hokamp K, Farrar GJ. Non-photoreceptor Expression of Tulp1 May Contribute to Extensive Retinal Degeneration in Tulp1-/- Mice. Front Neurosci 2020; 14:656. [PMID: 32655363 PMCID: PMC7325604 DOI: 10.3389/fnins.2020.00656] [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: 04/14/2020] [Accepted: 05/27/2020] [Indexed: 12/24/2022] Open
Abstract
Mutations in tubby like protein 1 gene (TULP1) are causative of early-onset recessive inherited retinal degenerations (IRDs); similarly, the Tulp1-/- mouse is also characterized by a rapid IRD. Tulp1 mRNA and protein expression was analyzed in wild type mouse retinas and expression data sets (NCBI) during early postnatal development. Comparative histology was undertaken in Tulp1-/-, rhodopsin-/- (Rho-/-) and retinal degeneration slow-/- (Rds-/-) mouse retinas. Bioinformatic analysis of predicted TULP1 interactors and IRD genes was performed. Peak expression of Tulp1 in healthy mouse retinas was detected at p8; of note, TULP1 was detected in both the outer and inner retina. Bioinformatic analysis indicated Tulp1 expression in retinal progenitor, photoreceptor and non-photoreceptor cells. While common features of photoreceptor degeneration were detected in Tulp1-/-, Rho-/-, and Rds-/- retinas, other alterations in bipolar, amacrine and ganglion cells were specific to Tulp1-/- mice. Additionally, predicted TULP1 interactors differed in various retinal cell types and new functions for TULP1 were suggested. A pilot bioinformatic analysis indicated that in a similar fashion to Tulp1, many other IRD genes were expressed in both inner and outer retinal cells at p4-p7. Our data indicate that expression of Tulp1 extends to multiple retinal cell types; lack of TULP1 may lead to primary degeneration not only of photoreceptor but also non-photoreceptor cells. Predicted interactors suggest widespread retinal functions for TULP1. Early and widespread expression of TULP1 and some other IRD genes in both the inner and outer retina highlights potential hurdles in the development of treatments for these IRDs.
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Affiliation(s)
- Arpad Palfi
- Department of Genetics, Trinity College Dublin, Dublin, Ireland
| | | | - Pete Humphries
- Department of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Karsten Hokamp
- Department of Genetics, Trinity College Dublin, Dublin, Ireland
| | - G Jane Farrar
- Department of Genetics, Trinity College Dublin, Dublin, Ireland
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85
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Sun D, Schur RM, Sears AE, Gao SQ, Sun W, Naderi A, Kern T, Palczewski K, Lu ZR. Stable Retinoid Analogue Targeted Dual pH-Sensitive Smart Lipid ECO/pDNA Nanoparticles for Specific Gene Delivery in the Retinal Pigment Epithelium. ACS APPLIED BIO MATERIALS 2020; 3:3078-3086. [PMID: 34327311 DOI: 10.1021/acsabm.0c00130] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Da Sun
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106
| | - Rebecca M Schur
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106
| | - Avery E Sears
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106
| | - Song-Qi Gao
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106
| | - Wenyu Sun
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106
| | - Amirreza Naderi
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106
| | - Timothy Kern
- Department of Ophthalmology, University of California Irvine, Irvine, CA 92697-7600
| | - Krzysztof Palczewski
- Department of Ophthalmology, University of California Irvine, Irvine, CA 92697-7600
| | - Zheng-Rong Lu
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106
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Cremers FPM, Lee W, Collin RWJ, Allikmets R. Clinical spectrum, genetic complexity and therapeutic approaches for retinal disease caused by ABCA4 mutations. Prog Retin Eye Res 2020; 79:100861. [PMID: 32278709 PMCID: PMC7544654 DOI: 10.1016/j.preteyeres.2020.100861] [Citation(s) in RCA: 162] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 03/13/2020] [Accepted: 03/18/2020] [Indexed: 12/18/2022]
Abstract
The ABCA4 protein (then called a “rim protein”) was first
identified in 1978 in the rims and incisures of rod photoreceptors. The
corresponding gene, ABCA4, was cloned in 1997, and variants
were identified as the cause of autosomal recessive Stargardt disease (STGD1).
Over the next two decades, variation in ABCA4 has been
attributed to phenotypes other than the classically defined STGD1 or fundus
flavimaculatus, ranging from early onset and fast progressing cone-rod dystrophy
and retinitis pigmentosa-like phenotypes to very late onset cases of mostly mild
disease sometimes resembling, and confused with, age-related macular
degeneration. Similarly, analysis of the ABCA4 locus uncovered
a trove of genetic information, including >1200 disease-causing mutations
of varying severity, and of all types – missense, nonsense, small
deletions/insertions, and splicing affecting variants, of which many are located
deep-intronic. Altogether, this has greatly expanded our understanding of
complexity not only of the diseases caused by ABCA4 mutations,
but of all Mendelian diseases in general. This review provides an in depth
assessment of the cumulative knowledge of ABCA4-associated retinopathy –
clinical manifestations, genetic complexity, pathophysiology as well as current
and proposed therapeutic approaches.
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Affiliation(s)
- Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, PO Box 9104, 6500 HE, Nijmegen, the Netherlands.
| | - Winston Lee
- Department of Ophthalmology, Columbia University, New York, NY, 10032, USA; Department of Genetics & Development, Columbia University, New York, NY, 10032, USA
| | - Rob W J Collin
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, PO Box 9104, 6500 HE, Nijmegen, the Netherlands
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, NY, 10032, USA; Department of Pathology & Cell Biology, Columbia University, New York, NY, 10032, USA.
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87
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Fontaine V, Monteiro E, Fournié M, Brazhnikova E, Boumedine T, Vidal C, Balducci C, Guibout L, Latil M, Dilda PJ, Veillet S, Sahel JA, Lafont R, Camelo S. Systemic administration of the di-apocarotenoid norbixin (BIO201) is neuroprotective, preserves photoreceptor function and inhibits A2E and lipofuscin accumulation in animal models of age-related macular degeneration and Stargardt disease. Aging (Albany NY) 2020; 12:6151-6171. [PMID: 32255762 PMCID: PMC7185133 DOI: 10.18632/aging.103014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 03/02/2020] [Indexed: 12/31/2022]
Abstract
Atrophic A\age-related macular degeneration (AMD) and Stargardt disease (STGD) are major blinding diseases affecting millions of patients worldwide, but no treatment is available. In dry AMD and STGD oxidative stress and subretinal accumulation of N-retinylidene-N-retinylethanolamine (A2E), a toxic by-product of the visual cycle, causes retinal pigment epithelium (RPE) and photoreceptor degeneration leading to visual impairment. Acute and chronic retinal degeneration following blue light damage (BLD) in BALB/c mice and aging of Abca4-/- Rdh8-/- mice, respectively, reproduce features of AMD and STGD. Efficacy of systemic administrations of 9'-cis-norbixin (norbixin), a natural di-apocarotenoid, prepared from Bixa orellana seeds with anti-oxidative properties, was evaluated during BLD in BALB/c mice, and in Abca4-/- Rdh8-/- mice of different ages, following three experimental designs: “preventive”, “early curative” and “late curative” supplementations. Norbixin injected intraperitoneally in BALB/c mice, maintained scotopic and photopic electroretinogram amplitude and was neuroprotective. Norbixin chronic oral administration for 6 months in Abca4-/- Rdh8-/- mice following the “early curative” supplementation showed optimal neuroprotection and maintenance of photoreceptor function and reduced ocular A2E accumulation. Thus, norbixin appears promising as a systemic drug candidate for both AMD and STGD treatment.
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Affiliation(s)
- Valérie Fontaine
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris 75012, France
| | - Elodie Monteiro
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris 75012, France
| | - Mylène Fournié
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris 75012, France
| | - Elena Brazhnikova
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris 75012, France
| | | | - Cécile Vidal
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris 75012, France
| | - Christine Balducci
- Biophytis, Sorbonne Université, Campus Pierre and Marie Curie, Paris 75005, France
| | - Louis Guibout
- Biophytis, Sorbonne Université, Campus Pierre and Marie Curie, Paris 75005, France
| | - Mathilde Latil
- Biophytis, Sorbonne Université, Campus Pierre and Marie Curie, Paris 75005, France
| | - Pierre J Dilda
- Biophytis, Sorbonne Université, Campus Pierre and Marie Curie, Paris 75005, France
| | - Stanislas Veillet
- Biophytis, Sorbonne Université, Campus Pierre and Marie Curie, Paris 75005, France
| | - José-Alain Sahel
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris 75012, France
| | - René Lafont
- Biophytis, Sorbonne Université, Campus Pierre and Marie Curie, Paris 75005, France
| | - Serge Camelo
- Biophytis, Sorbonne Université, Campus Pierre and Marie Curie, Paris 75005, France
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Fang Y, Tschulakow A, Taubitz T, Illing B, Biesemeier A, Julien-Schraermeyer S, Radu RA, Jiang Z, Schraermeyer U. Fundus autofluorescence, spectral-domain optical coherence tomography, and histology correlations in a Stargardt disease mouse model. FASEB J 2020; 34:3693-3714. [PMID: 31989709 DOI: 10.1096/fj.201901784rr] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 12/17/2019] [Accepted: 12/17/2019] [Indexed: 01/09/2023]
Abstract
Stargardt disease (STGD1), known as inherited retinal dystrophy, is caused by ABCA4 mutations. The pigmented Abca4-/- mouse strain only reflects the early stage of STGD1 since it is devoid of retinal degeneration. This blue light-illuminated pigmented Abca4-/- mouse model presented retinal pigment epithelium (RPE) and photoreceptor degeneration which was similar to the advanced STGD1 phenotype. In contrast, wild-type mice showed no RPE degeneration after blue light illumination. In Abca4-/- mice, the acute blue light diminished the mean autofluorescence (AF) intensity in both fundus short-wavelength autofluorescence (SW-AF) and near-infrared autofluorescence (NIR-AF) modalities correlating with reduced levels of bisretinoid-fluorophores. Blue light-induced RPE cellular damage preceded the photoreceptors loss. In late-stage STGD1-like patient and blue light-illuminated Abca4-/- mice, lipofuscin and melanolipofuscin granules were found to contribute to NIR-AF, indicated by the colocalization of lipofuscin-AF and NIR-AF under the fluorescence microscope. In this mouse model, the correlation between in vivo and ex vivo assessments revealed histological characteristics of fundus AF abnormalities. The flecks which are hyper AF in both SW-AF and NIR-AF corresponded to the subretinal macrophages fully packed with pigment granules (lipofuscin, melanin, and melanolipofuscin). This mouse model, which has the phenotype of advanced STGD1, is important to understand the histopathology of Stargardt disease.
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Affiliation(s)
- Yuan Fang
- Division of Experimental Vitreoretinal Surgery, Center for Ophthalmology, Institute of Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Alexander Tschulakow
- Division of Experimental Vitreoretinal Surgery, Center for Ophthalmology, Institute of Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
- Preclinical Drug Assessment, STZ Ocutox, Hechingen, Germany
| | - Tatjana Taubitz
- Division of Experimental Vitreoretinal Surgery, Center for Ophthalmology, Institute of Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Barbara Illing
- Division of Experimental Vitreoretinal Surgery, Center for Ophthalmology, Institute of Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Antje Biesemeier
- Division of Experimental Vitreoretinal Surgery, Center for Ophthalmology, Institute of Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Sylvie Julien-Schraermeyer
- Division of Experimental Vitreoretinal Surgery, Center for Ophthalmology, Institute of Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
- Preclinical Drug Assessment, STZ Ocutox, Hechingen, Germany
| | - Roxana A Radu
- UCLA Stein Eye Institute, Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Zhichun Jiang
- UCLA Stein Eye Institute, Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Ulrich Schraermeyer
- Division of Experimental Vitreoretinal Surgery, Center for Ophthalmology, Institute of Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
- Preclinical Drug Assessment, STZ Ocutox, Hechingen, Germany
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89
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Valdés-Sánchez L, Calado SM, de la Cerda B, Aramburu A, García-Delgado AB, Massalini S, Montero-Sánchez A, Bhatia V, Rodríguez-Bocanegra E, Diez-Lloret A, Rodríguez-Martínez D, Chakarova C, Bhattacharya SS, Díaz-Corrales FJ. Retinal pigment epithelium degeneration caused by aggregation of PRPF31 and the role of HSP70 family of proteins. Mol Med 2019; 26:1. [PMID: 31892304 PMCID: PMC6938640 DOI: 10.1186/s10020-019-0124-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 12/05/2019] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Mutations in pre-mRNA splicing factor PRPF31 can lead to retinitis pigmentosa (RP). Although the exact disease mechanism remains unknown, it has been hypothesized that haploinsufficiency might be involved in the pathophysiology of the disease. METHODS In this study, we have analyzed a mouse model containing the p.A216P mutation in Prpf31 gene. RESULTS We found that mutant Prpf31 protein produces cytoplasmic aggregates in the retinal pigment epithelium and decreasing the protein levels of this splicing factor in the nucleus. Additionally, normal protein was recruited in insoluble aggregates when the mutant protein was overexpressed in vitro. In response to protein aggregation, Hspa4l is overexpressed. This member of the HSP70 family of chaperones might contribute to the correct folding and solubilization of the mutant protein, allowing its translocation to the nucleus. CONCLUSIONS Our data suggests that a mechanism haploinsufficiency and dominant-negative is involved in retinal degeneration due to mutations in PRPF31. HSP70 over-expression might be a new therapeutic target for the treatment of retinal degeneration due to PRPF31 mutations.
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Affiliation(s)
- Lourdes Valdés-Sánchez
- Regeneration and Cell Therapy Department, Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER (Junta de Andalucía), CSIC, Universidad de Sevilla, Universidad Pablo de Olavide, Avda. Americo Vespucio 24, 41092, Seville, Spain
| | - Sofia M Calado
- Regeneration and Cell Therapy Department, Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER (Junta de Andalucía), CSIC, Universidad de Sevilla, Universidad Pablo de Olavide, Avda. Americo Vespucio 24, 41092, Seville, Spain
- Present Address: Center for Biomedical Research (CBMR), University of Algarve, 8800-139, Faro, Portugal
| | - Berta de la Cerda
- Regeneration and Cell Therapy Department, Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER (Junta de Andalucía), CSIC, Universidad de Sevilla, Universidad Pablo de Olavide, Avda. Americo Vespucio 24, 41092, Seville, Spain
| | - Ana Aramburu
- Regeneration and Cell Therapy Department, Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER (Junta de Andalucía), CSIC, Universidad de Sevilla, Universidad Pablo de Olavide, Avda. Americo Vespucio 24, 41092, Seville, Spain
- Present Address: Clinique de l'Oeil, Avenue Bois de la Chapelle 15, 1213, Onex, Switzerland
| | - Ana Belén García-Delgado
- Regeneration and Cell Therapy Department, Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER (Junta de Andalucía), CSIC, Universidad de Sevilla, Universidad Pablo de Olavide, Avda. Americo Vespucio 24, 41092, Seville, Spain
| | - Simone Massalini
- Regeneration and Cell Therapy Department, Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER (Junta de Andalucía), CSIC, Universidad de Sevilla, Universidad Pablo de Olavide, Avda. Americo Vespucio 24, 41092, Seville, Spain
- Present Address: Center for Molecular and Cellular Bioengineering (CMCB) DFG-Research Center for Regenerative Therapies Dresden (CRTD) Cluster of Excellence, Technische Universität Dresden, Fetscherstraße, 105 01307, Dresden, Germany
| | - Adoración Montero-Sánchez
- Regeneration and Cell Therapy Department, Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER (Junta de Andalucía), CSIC, Universidad de Sevilla, Universidad Pablo de Olavide, Avda. Americo Vespucio 24, 41092, Seville, Spain
| | - Vaibhav Bhatia
- Regeneration and Cell Therapy Department, Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER (Junta de Andalucía), CSIC, Universidad de Sevilla, Universidad Pablo de Olavide, Avda. Americo Vespucio 24, 41092, Seville, Spain
| | - Eduardo Rodríguez-Bocanegra
- Regeneration and Cell Therapy Department, Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER (Junta de Andalucía), CSIC, Universidad de Sevilla, Universidad Pablo de Olavide, Avda. Americo Vespucio 24, 41092, Seville, Spain
- Present Address: Universitätsklinikum Tübingen, Forschungsinstitut für Augenheilkunde, Elfriede-Aulhorn-Str. 7, 72076, Tübingen, Germany
| | - Andrea Diez-Lloret
- Regeneration and Cell Therapy Department, Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER (Junta de Andalucía), CSIC, Universidad de Sevilla, Universidad Pablo de Olavide, Avda. Americo Vespucio 24, 41092, Seville, Spain
| | - Daniel Rodríguez-Martínez
- Regeneration and Cell Therapy Department, Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER (Junta de Andalucía), CSIC, Universidad de Sevilla, Universidad Pablo de Olavide, Avda. Americo Vespucio 24, 41092, Seville, Spain
| | - Christina Chakarova
- Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK
| | - Shom S Bhattacharya
- Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK.
| | - Francisco J Díaz-Corrales
- Regeneration and Cell Therapy Department, Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER (Junta de Andalucía), CSIC, Universidad de Sevilla, Universidad Pablo de Olavide, Avda. Americo Vespucio 24, 41092, Seville, Spain.
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90
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Zhang Q, Presswalla F, Calton M, Charniga C, Stern J, Temple S, Vollrath D, Zacks DN, Ali RR, Thompson DA, Miller JML. Highly Differentiated Human Fetal RPE Cultures Are Resistant to the Accumulation and Toxicity of Lipofuscin-Like Material. Invest Ophthalmol Vis Sci 2019; 60:3468-3479. [PMID: 31408109 PMCID: PMC6692057 DOI: 10.1167/iovs.19-26690] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Purpose The accumulation of undigestible autofluorescent material (UAM), termed lipofuscin in vivo, is a hallmark of aged RPE. Lipofuscin derives, in part, from the incomplete degradation of phagocytized photoreceptor outer segments (OS). Whether this accumulated waste is toxic is unclear. We therefore investigated the effects of UAM in highly differentiated human fetal RPE (hfRPE) cultures. Methods Unmodified and photo-oxidized OS were fed daily to confluent cultures of ARPE-19 RPE or hfRPE. The emission spectrum, composition, and morphology of resulting UAM were measured and compared to in vivo lipofuscin. Effects of UAM on multiple RPE phenotypes were assessed. Results Compared to ARPE-19, hfRPE were markedly less susceptible to UAM buildup. Accumulated UAM in hfRPE initially resembled the morphology of lipofuscin from AMD eyes, but compacted and shifted spectrum over time to resemble lipofuscin from healthy aged human RPE. UAM accumulation mildly reduced transepithelial electrical resistance, ketogenesis, certain RPE differentiation markers, and phagocytosis efficiency, while inducing senescence and rare, focal pockets of epithelial-mesenchymal transition. However, it had no effects on mitochondrial oxygen consumption rate, certain other RPE differentiation markers, secretion of drusen components or polarity markers, nor cell death. Conclusions hfRPE demonstrates a remarkable resistance to UAM accumulation, suggesting mechanisms for efficient OS processing that may be lost in other RPE culture models. Furthermore, while UAM alters hfRPE phenotype, the effects are modest, consistent with conflicting reports in the literature on the toxicity of lipofuscin. Our results suggest that healthy RPE may adequately adapt to and tolerate lipofuscin accumulation.
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Affiliation(s)
- Qitao Zhang
- Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
| | - Feriel Presswalla
- Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
| | - Melissa Calton
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States
| | - Carol Charniga
- Neural Stem Cell Institute, Rensselaer, New York, United States
| | - Jeffrey Stern
- Neural Stem Cell Institute, Rensselaer, New York, United States
| | - Sally Temple
- Neural Stem Cell Institute, Rensselaer, New York, United States
| | - Douglas Vollrath
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States
| | - David N Zacks
- Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
| | - Robin R Ali
- Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States.,UCL Institute of Ophthalmology, London, United Kingdom
| | - Debra A Thompson
- Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
| | - Jason M L Miller
- Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
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91
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Fadaie Z, Khan M, Del Pozo‐Valero M, Cornelis SS, Ayuso C, Cremers FPM, Roosing S, The ABCA4 study group. Identification of splice defects due to noncanonical splice site or deep-intronic variants in ABCA4. Hum Mutat 2019; 40:2365-2376. [PMID: 31397521 PMCID: PMC6899986 DOI: 10.1002/humu.23890] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 07/30/2019] [Accepted: 08/04/2019] [Indexed: 12/25/2022]
Abstract
Pathogenic variants in the ATP-binding cassette transporter A4 (ABCA4) gene cause a continuum of retinal disease phenotypes, including Stargardt disease. Noncanonical splice site (NCSS) and deep-intronic variants constitute a large fraction of disease-causing alleles, defining the functional consequences of which remains a challenge. We aimed to determine the effect on splicing of nine previously reported or unpublished NCSS variants, one near exon splice variant and nine deep-intronic variants in ABCA4, using in vitro splice assays in human embryonic kidney 293T cells. Reverse transcription-polymerase chain reaction and Sanger sequence analysis revealed splicing defects for 12 out of 19 variants. Four deep-intronic variants create pseudoexons or elongate the upstream exon. Furthermore, eight NCSS variants cause a partial deletion or skipping of one or more exons in messenger RNAs. Among the 12 variants, nine lead to premature stop codons and predicted truncated ABCA4 proteins. At least two deep-intronic variants affect splice enhancer and silencer motifs and, therefore, these conserved sequences should be carefully evaluated when predicting the outcome of NCSS and deep-intronic variants.
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Affiliation(s)
- Zeinab Fadaie
- Department of Human Genetics, Donders Institute for Brain, Cognition and BehaviorRadboud University Medical CenterNijmegenThe Netherlands
| | - Mubeen Khan
- Department of Human Genetics, Donders Institute for Brain, Cognition and BehaviorRadboud University Medical CenterNijmegenThe Netherlands
| | - Marta Del Pozo‐Valero
- Department of Human Genetics, Donders Institute for Brain, Cognition and BehaviorRadboud University Medical CenterNijmegenThe Netherlands
- Department of Genetics, Instituto de Investigación Sanitaria–Fundación Jiménez Díaz University HospitalUniversidad Autónoma de Madrid (IIS‐FJD, UAM)MadridSpain
| | - Stéphanie S. Cornelis
- Department of Human Genetics, Donders Institute for Brain, Cognition and BehaviorRadboud University Medical CenterNijmegenThe Netherlands
| | - Carmen Ayuso
- Department of Genetics, Instituto de Investigación Sanitaria–Fundación Jiménez Díaz University HospitalUniversidad Autónoma de Madrid (IIS‐FJD, UAM)MadridSpain
| | - Frans P. M. Cremers
- Department of Human Genetics, Donders Institute for Brain, Cognition and BehaviorRadboud University Medical CenterNijmegenThe Netherlands
| | - Susanne Roosing
- Department of Human Genetics, Donders Institute for Brain, Cognition and BehaviorRadboud University Medical CenterNijmegenThe Netherlands
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92
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Tracewska AM, Kocyła-Karczmarewicz B, Rafalska A, Murawska J, Jakubaszko-Jablonska J, Rydzanicz M, Stawiński P, Ciara E, Khan MI, Henkes A, Hoischen A, Gilissen C, van de Vorst M, Cremers FPM, Płoski R, Chrzanowska KH. Genetic Spectrum of ABCA4-Associated Retinal Degeneration in Poland. Genes (Basel) 2019; 10:E959. [PMID: 31766579 PMCID: PMC6947411 DOI: 10.3390/genes10120959] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 11/05/2019] [Accepted: 11/19/2019] [Indexed: 12/03/2022] Open
Abstract
Mutations in retina-specific ATP-binding cassette transporter 4 (ABCA4) are responsible for over 95% of cases of Stargardt disease (STGD), as well as a minor proportion of retinitis pigmentosa (RP) and cone-rod dystrophy cases (CRD). Since the knowledge of the genetic causes of inherited retinal diseases (IRDs) in Poland is still scarce, the purpose of this study was to identify pathogenic ABCA4 variants in a subgroup of Polish IRD patients. We recruited 67 families with IRDs as a part of a larger study. The patients were screened with next generation sequencing using a molecular inversion probes (MIPs)-based technique targeting 108 genes involved in the pathogenesis of IRDs. All identified mutations were validated and their familial segregation was tested using Sanger sequencing. In the case of the most frequent complex allele, consisting of two variants in exon 12 and 21, familial segregation was tested using restriction fragment length polymorphism (RFLP). The most prevalent variant, a complex change c.[1622T>C;3113C>T], p.[Leu541Pro;Ala1038Val], was found in this cohort in 54% of all solved ABCA4-associated disorder cases, which is the highest frequency reported thus far. Additionally, we identified nine families displaying a pseudo-dominant mode of inheritance, indicating a high frequency of pathogenic variants within this population.
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Affiliation(s)
- Anna M. Tracewska
- DNA Analysis Unit, ŁUKASIEWICZ Research Network–PORT Polish Center for Technology Development, 54-066 Wrocław, Poland
| | | | - Agnieszka Rafalska
- Department of Ophthalmology, Wrocław Medical University, 50-556 Wrocław, Poland; (A.R.); (J.J.-J.)
| | - Joanna Murawska
- Department of Ophthalmology, University Clinical Centre, 80-214 Gdańsk, Poland;
| | - Joanna Jakubaszko-Jablonska
- Department of Ophthalmology, Wrocław Medical University, 50-556 Wrocław, Poland; (A.R.); (J.J.-J.)
- Department of Paediatric Traumatology and Emergency Medicine, Wrocław Medical University, 50-345 Wrocław, Poland
- SPEKTRUM Ophthalmology Clinic, 53-334 Wrocław, Poland
| | - Małgorzata Rydzanicz
- Department of Medical Genetics, Medical University of Warsaw, 02-106 Warsaw, Poland; (M.R.); (P.S.); (R.P.)
| | - Piotr Stawiński
- Department of Medical Genetics, Medical University of Warsaw, 02-106 Warsaw, Poland; (M.R.); (P.S.); (R.P.)
| | - Elżbieta Ciara
- Children’s Memorial Health Institute, 04-730 Warsaw, Poland; (B.K.-K.); (E.C.)
| | - Muhammad Imran Khan
- Department of Human Genetics, Radboud university medical center, PO Box 9101, 6500 HB Nijmegen, The Netherland; (M.I.K.); (A.H.); (A.H.); (M.v.d.V.); (F.P.M.C.)
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, PO Box 9104, 6500 HE Nijmegen, The Netherlands;
| | - Arjen Henkes
- Department of Human Genetics, Radboud university medical center, PO Box 9101, 6500 HB Nijmegen, The Netherland; (M.I.K.); (A.H.); (A.H.); (M.v.d.V.); (F.P.M.C.)
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, PO Box 9104, 6500 HE Nijmegen, The Netherlands;
| | - Alexander Hoischen
- Department of Human Genetics, Radboud university medical center, PO Box 9101, 6500 HB Nijmegen, The Netherland; (M.I.K.); (A.H.); (A.H.); (M.v.d.V.); (F.P.M.C.)
- Department of Internal Medicine and Radboud Center for Infectious Diseases (RCI), Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Christian Gilissen
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, PO Box 9104, 6500 HE Nijmegen, The Netherlands;
- Department of Internal Medicine and Radboud Center for Infectious Diseases (RCI), Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Maartje van de Vorst
- Department of Human Genetics, Radboud university medical center, PO Box 9101, 6500 HB Nijmegen, The Netherland; (M.I.K.); (A.H.); (A.H.); (M.v.d.V.); (F.P.M.C.)
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, PO Box 9104, 6500 HE Nijmegen, The Netherlands;
| | - Frans P. M. Cremers
- Department of Human Genetics, Radboud university medical center, PO Box 9101, 6500 HB Nijmegen, The Netherland; (M.I.K.); (A.H.); (A.H.); (M.v.d.V.); (F.P.M.C.)
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, PO Box 9104, 6500 HE Nijmegen, The Netherlands;
| | - Rafał Płoski
- Department of Medical Genetics, Medical University of Warsaw, 02-106 Warsaw, Poland; (M.R.); (P.S.); (R.P.)
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93
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Prevalence of ABCA4 Deep-Intronic Variants and Related Phenotype in An Unsolved "One-Hit" Cohort with Stargardt Disease. Int J Mol Sci 2019; 20:ijms20205053. [PMID: 31614660 PMCID: PMC6829239 DOI: 10.3390/ijms20205053] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 09/24/2019] [Accepted: 10/09/2019] [Indexed: 02/06/2023] Open
Abstract
We investigated the prevalence of reported deep-intronic variants in a French cohort of 70 patients with Stargardt disease harboring a monoallelic pathogenic variant on the exonic regions of ABCA4. Direct Sanger sequencing of selected intronic regions of ABCA4 was conducted. Complete phenotypic analysis and correlation with the genotype was performed in case a known intronic pathogenic variant was identified. All other variants found on the analyzed sequences were queried for minor allele frequency and possible pathogenicity by in silico predictions. The second mutated allele was found in 14 (20%) subjects. The three known deep-intronic variants found were c.5196+1137G>A in intron 36 (6 subjects), c.4539+2064C>T in intron 30 (4 subjects) and c.4253+43G>A in intron 28 (4 subjects). Even though the phenotype depends on the compound effect of the biallelic variants, a genotype-phenotype correlation suggests that the c.5196+1137G>A was mostly associated with a mild phenotype and the c.4539+2064C>T with a more severe one. A variable effect was instead associated with the variant c.4253+43G>A. In addition, two novel variants, c.768+508A>G and c.859-245_859-243delinsTGA never associated with Stargardt disease before, were identified and a possible splice defect was predicted in silico. Our study calls for a larger cohort analysis including targeted locus sequencing and 3D protein modeling to better understand phenotype-genotype correlations associated with deep-intronic changes and patients’ selection for clinical trials.
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94
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Dyka FM, Molday LL, Chiodo VA, Molday RS, Hauswirth WW. Dual ABCA4-AAV Vector Treatment Reduces Pathogenic Retinal A2E Accumulation in a Mouse Model of Autosomal Recessive Stargardt Disease. Hum Gene Ther 2019; 30:1361-1370. [PMID: 31418294 DOI: 10.1089/hum.2019.132] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Autosomal recessive Stargardt disease is the most common inherited macular degeneration in humans. It is caused by mutations in the retina-specific ATP binding cassette transporter A4 (ABCA4) that is essential for the clearance of all-trans-retinal from photoreceptor cells. Loss of this function results in the accumulation of toxic bisretinoids in the outer segment disk membranes and their subsequent transfer into adjacent retinal pigment epithelium (RPE) cells. This ultimately leads to the Stargardt disease phenotype of increased retinal autofluorescence and progressive RPE and photoreceptor cell loss. Adeno-associated virus (AAV) vectors have been widely used in gene therapeutic applications, but their limited cDNA packaging capacity of ∼4.5 kb has impeded their use for transgenes exceeding this limit. AAV dual vectors were developed to overcome this size restriction. In this study, we have evaluated the in vitro expression of ABCA4 using three options: overlap, transplicing, and hybrid ABCA4 dual vector systems. The hybrid system was the most efficient of these dual vector alternatives and used to express the full-length ABCA4 in Abca4-/- mice. The full-length ABCA4 protein correctly localized to photoreceptor outer segments. Moreover, treatment of Abca4-/- mice with this ABCA4 hybrid dual vector system resulted in a reduced accumulation of the lipofuscin/N-retinylidene-N-retinylethanolamine (A2E) autofluorescence in vivo, and retinal A2E quantification supported these findings. These results show that the hybrid AAV dual vector option is both safe and therapeutic in mice, and the delivered ABCA4 transgene is functional and has a significant effect on reducing A2E accumulation in the Abca4-/- mouse model of Stargardt disease.
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Affiliation(s)
- Frank M Dyka
- Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, Florida
| | - Laurie L Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Vince A Chiodo
- Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, Florida
| | - Robert S Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - William W Hauswirth
- Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, Florida
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95
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Non-viral Gene Therapy for Stargardt Disease with ECO/pRHO-ABCA4 Self-Assembled Nanoparticles. Mol Ther 2019; 28:293-303. [PMID: 31611143 DOI: 10.1016/j.ymthe.2019.09.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 08/10/2019] [Accepted: 09/06/2019] [Indexed: 12/20/2022] Open
Abstract
Stargardt disease (STGD) is an autosomal recessive retinal disorder caused by a monogenic ABCA4 mutation. Currently, there is no effective therapy to cure Stargardt disease. The replacement of mutated ABCA4 with a functional gene remains an attractive strategy. In this study, we have developed a non-viral gene therapy using nanoparticles self-assembled by a multifunctional pH-sensitive amino lipid ECO and a therapeutic ABCA4 plasmid. The nanoparticles mediated efficient intracellular gene transduction in wild-type (WT) and Abca4-/- mice. Specific ABCA4 expression in the outer segment of photoreceptors was achieved by incorporating a rhodopsin promoter into the plasmids. The ECO/pRHO-ABCA4 nanoparticles induced substantial and specific ABCA4 expression for at least 8 months, 35% reduction in A2E accumulation on average, and a delayed Stargardt disease progression for at least 6 months in Abca4-/- mice. ECO/plasmid nanoparticles constitute a promising non-viral gene therapy platform for Stargardt disease and other visual dystrophies.
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96
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Power M, Das S, Schütze K, Marigo V, Ekström P, Paquet-Durand F. Cellular mechanisms of hereditary photoreceptor degeneration - Focus on cGMP. Prog Retin Eye Res 2019; 74:100772. [PMID: 31374251 DOI: 10.1016/j.preteyeres.2019.07.005] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 07/25/2019] [Accepted: 07/29/2019] [Indexed: 12/21/2022]
Abstract
The cellular mechanisms underlying hereditary photoreceptor degeneration are still poorly understood, a problem that is exacerbated by the enormous genetic heterogeneity of this disease group. However, the last decade has yielded a wealth of new knowledge on degenerative pathways and their diversity. Notably, a central role of cGMP-signalling has surfaced for photoreceptor cell death triggered by a subset of disease-causing mutations. In this review, we examine key aspects relevant for photoreceptor degeneration of hereditary origin. The topics covered include energy metabolism, epigenetics, protein quality control, as well as cGMP- and Ca2+-signalling, and how the related molecular and metabolic processes may trigger photoreceptor demise. We compare and integrate evidence on different cell death mechanisms that have been associated with photoreceptor degeneration, including apoptosis, necrosis, necroptosis, and PARthanatos. A special focus is then put on the mechanisms of cGMP-dependent cell death and how exceedingly high photoreceptor cGMP levels may cause activation of Ca2+-dependent calpain-type proteases, histone deacetylases and poly-ADP-ribose polymerase. An evaluation of the available literature reveals that a large group of patients suffering from hereditary photoreceptor degeneration carry mutations that are likely to trigger cGMP-dependent cell death, making this pathway a prime target for future therapy development. Finally, an outlook is given into technological and methodological developments that will with time likely contribute to a comprehensive overview over the entire metabolic complexity of photoreceptor cell death. Building on such developments, new imaging technology and novel biomarkers may be used to develop clinical test strategies, that fully consider the genetic heterogeneity of hereditary retinal degenerations, in order to facilitate clinical testing of novel treatment approaches.
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Affiliation(s)
- Michael Power
- Cell Death Mechanism Group, Institute for Ophthalmic Research, University of Tübingen, Germany; Centre for Integrative Neurosciences (CIN), University of Tübingen, Germany; Graduate Training Centre of Neuroscience (GTC), University of Tübingen, Germany
| | - Soumyaparna Das
- Cell Death Mechanism Group, Institute for Ophthalmic Research, University of Tübingen, Germany; Graduate Training Centre of Neuroscience (GTC), University of Tübingen, Germany
| | | | - Valeria Marigo
- Department of Life Sciences, University of Modena and Reggio Emilia, Italy
| | - Per Ekström
- Ophthalmology, Department of Clinical Sciences Lund, Faculty of Medicine, Lund University, Sweden
| | - François Paquet-Durand
- Cell Death Mechanism Group, Institute for Ophthalmic Research, University of Tübingen, Germany.
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97
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Lu W, Campagno KE, Tso HY, Cenaj A, Laties AM, Carlsson LG, Mitchell CH. Oral Delivery of the P2Y12 Receptor Antagonist Ticagrelor Prevents Loss of Photoreceptors in an ABCA4-/- Mouse Model of Retinal Degeneration. Invest Ophthalmol Vis Sci 2019; 60:3046-3053. [PMID: 31319418 PMCID: PMC6640265 DOI: 10.1167/iovs.19-27241] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 06/10/2019] [Indexed: 01/22/2023] Open
Abstract
Purpose Accumulation of lysosomal waste is linked to neurodegeneration in multiple diseases, and pharmacologic enhancement of lysosomal activity is hypothesized to reduce pathology. An excessive accumulation of lysosomal-associated lipofuscin waste and an elevated lysosomal pH occur in retinal pigment epithelial cells of the ABCA4-/- mouse model of Stargardt's retinal degeneration. As treatment with the P2Y12 receptor antagonist ticagrelor was previously shown to lower lysosomal pH and lipofuscin-like autofluorescence in these cells, we asked whether oral delivery of ticagrelor also prevented photoreceptor loss. Methods Moderate light exposure was used to accelerate photoreceptor loss in albino ABCA4-/- mice as compared to BALB/c controls. Ticagrelor (0.1%-0.15%) was added to mouse chow for between 1 and 10 months. Photoreceptor function was determined with electroretinograms, while cell survival was determined using optical coherence tomography and histology. Results Protection by ticagrelor was demonstrated functionally by using the electroretinogram, as ticagrelor-treated ABCA4-/- mice had increased a- and b-waves compared to untreated mice. Mice receiving ticagrelor treatment had a thicker outer nuclear layer, as measured with both optical coherence tomography and histologic sections. Ticagrelor decreased expression of LAMP1, implicating enhanced lysosomal function. No signs of retinal bleeding were observed after prolonged treatment with ticagrelor. Conclusions Oral treatment with ticagrelor protected photoreceptors in the ABCA4-/- mouse, which is consistent with enhanced lysosomal function. As mouse ticagrelor exposure levels were clinically relevant, the drug may be of benefit in preventing the loss of photoreceptors in Stargardt's disease and other neurodegenerations associated with lysosomal dysfunction.
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Affiliation(s)
- Wennan Lu
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Keith E. Campagno
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Huen-Yee Tso
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Aurora Cenaj
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Alan M. Laties
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Leif G. Carlsson
- Bioscience Cardiovascular Research and Early Development Cardiovascular, Renal and Metabolism BioPhamaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Claire H. Mitchell
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania, United States
- Department of Physiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States
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98
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Rozanowska M, Edge R, Land EJ, Navaratnam S, Sarna T, Truscott TG. Scavenging of Retinoid Cation Radicals by Urate, Trolox, and α-, β-, γ-, and δ-Tocopherols. Int J Mol Sci 2019; 20:ijms20112799. [PMID: 31181693 PMCID: PMC6600601 DOI: 10.3390/ijms20112799] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 06/02/2019] [Accepted: 06/03/2019] [Indexed: 12/17/2022] Open
Abstract
Retinoids are present in human tissues exposed to light and under increased risk of oxidative stress, such as the retina and skin. Retinoid cation radicals can be formed as a result of the interaction between retinoids and other radicals or photoexcitation with light. It has been shown that such semi-oxidized retinoids can oxidize certain amino acids and proteins, and that α-tocopherol can scavenge the cation radicals of retinol and retinoic acid. The aim of this study was to determine (i) whether β-, γ-, and δ-tocopherols can also scavenge these radicals, and (ii) whether tocopherols can scavenge the cation radicals of another form of vitamin A—retinal. The retinoid cation radicals were generated by the pulse radiolysis of benzene or aqueous solution in the presence of a selected retinoid under oxidizing conditions, and the kinetics of retinoid cation radical decays were measured in the absence and presence of different tocopherols, Trolox or urate. The bimolecular rate constants are the highest for the scavenging of cation radicals of retinal, (7 to 8) × 109 M−1·s−1, followed by retinoic acid, (0.03 to 5.6) × 109 M−1·s−1, and retinol, (0.08 to 1.6) × 108 M−1·s−1. Delta-tocopherol is the least effective scavenger of semi-oxidized retinol and retinoic acid. The hydrophilic analogue of α-tocopherol, Trolox, is substantially less efficient at scavenging retinoid cation radicals than α-tocopherol and urate, but it is more efficient at scavenging the cation radicals of retinoic acid and retinol than δ-tocopherol. The scavenging rate constants indicate that tocopherols can effectively compete with amino acids and proteins for retinoid cation radicals, thereby protecting these important biomolecules from oxidation. Our results provide another mechanism by which tocopherols can diminish the oxidative damage to the skin and retina and thereby protect from skin photosensitivity and the development and/or progression of changes in blinding retinal diseases such as Stargardt’s disease and age-related macular degeneration (AMD).
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Affiliation(s)
- Malgorzata Rozanowska
- Cardiff Institute of Tissue Engineering and Repair, Cardiff University, Wales CF10 3AX, UK.
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales CF24 4HQ, UK.
| | - Ruth Edge
- Dalton Cumbrian Facility, The University of Manchester, Westlakes Science Park, Moor Row, Cumbria CA24 3HA, UK.
| | - Edward J Land
- Free Radical Research Facility, Science and Technology Facilities Council (STFC) Daresbury Laboratory, Warrington WA4 4AD, UK.
| | - Suppiah Navaratnam
- Biomedical Sciences Research Institute, University of Salford, Manchester M5 4WT, UK.
| | - Tadeusz Sarna
- Department of Biophysics, Faculty of Biotechnology, Jagiellonian University, 30-387 Krakow, Poland.
| | - T George Truscott
- School of Chemical and Physical Sciences, Lennard-Jones Building, Keele University, Staffordshire ST5 5BG, UK.
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99
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Cicinelli MV, Battista M, Starace V, Battaglia Parodi M, Bandello F. Monitoring and Management of the Patient with Stargardt Disease. CLINICAL OPTOMETRY 2019; 11:151-165. [PMID: 31819694 PMCID: PMC6886536 DOI: 10.2147/opto.s226595] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 11/16/2019] [Indexed: 05/10/2023]
Abstract
Stargardt disease (STGD1) represents one of the major common causes of inherited irreversible visual loss. Due to its high phenotypic and genotypic heterogeneity, STGD1 is a complex disease to understand. Non-invasive imaging, biochemical, and genetic advances have led to substantial improvements in unveiling the disease processes and novel promising therapeutic landscapes have been proposed. This review recapitulates the modalities for monitoring patients with STGD1 and the therapeutic options currently under investigation for the different stages of the disease.
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Affiliation(s)
- Maria Vittoria Cicinelli
- Department of Ophthalmology, University Vita-Salute, IRCCS Ospedale San Raffaele, Milan, Italy
- Correspondence: Maria Vittoria Cicinelli Department of Ophthalmology, San Raffaele Vita-Salute University, Via Olgettina, 60, Milano20132, ItalyTel +39 02 26432648Fax +39 02 26483643 Email
| | - Marco Battista
- Department of Ophthalmology, University Vita-Salute, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Vincenzo Starace
- Department of Ophthalmology, University Vita-Salute, IRCCS Ospedale San Raffaele, Milan, Italy
| | | | - Francesco Bandello
- Department of Ophthalmology, University Vita-Salute, IRCCS Ospedale San Raffaele, Milan, Italy
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