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Annan WE, Asamani EOA, White D. Mathematical model for rod outer segment dynamics during retinal detachment. PLoS One 2024; 19:e0297419. [PMID: 38848326 PMCID: PMC11161088 DOI: 10.1371/journal.pone.0297419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 05/23/2024] [Indexed: 06/09/2024] Open
Abstract
Retinal detachment (RD) is the separation of the neural layer from the retinal pigmented epithelium thereby preventing the supply of nutrients to the cells within the neural layer of the retina. In vertebrates, primary photoreceptor cells consisting of rods and cones undergo daily renewal of their outer segment through the addition of disc-like structures and shedding of these discs at their distal end. When the retina detaches, the outer segment of these cells begins to degenerate and, if surgical procedures for reattachment are not done promptly, the cells can die and lead to blindness. The precise effect of RD on the renewal process is not well understood. Additionally, a time frame within which reattachment of the retina can restore proper photoreceptor cell function is not known. Focusing on rod cells, we propose a mathematical model to clarify the influence of retinal detachment on the renewal process. Our model simulation and analysis suggest that RD stops or significantly reduces the formation of new discs and that an alternative removal mechanism is needed to explain the observed degeneration during RD. Sensitivity analysis of our model parameters points to the disc removal rate as the key regulator of the critical time within which retinal reattachment can restore proper photoreceptor cell function.
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Affiliation(s)
- William Ebo Annan
- Department of Mathematics, Clarkson University, Potsdam, NY, United States of America
| | | | - Diana White
- Department of Mathematics, Clarkson University, Potsdam, NY, United States of America
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2
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Rutan Woods CT, Makia MS, Lewis TR, Crane R, Zeibak S, Yu P, Kakakhel M, Castillo CM, Arshavsky VY, Naash MI, Al-Ubaidi MR. Downregulation of rhodopsin is an effective therapeutic strategy in ameliorating peripherin-2-associated inherited retinal disorders. Nat Commun 2024; 15:4756. [PMID: 38834544 PMCID: PMC11150396 DOI: 10.1038/s41467-024-48846-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 05/15/2024] [Indexed: 06/06/2024] Open
Abstract
Given the absence of approved treatments for pathogenic variants in Peripherin-2 (PRPH2), it is imperative to identify a universally effective therapeutic target for PRPH2 pathogenic variants. To test the hypothesis that formation of the elongated discs in presence of PRPH2 pathogenic variants is due to the presence of the full complement of rhodopsin in absence of the required amounts of functional PRPH2. Here we demonstrate the therapeutic potential of reducing rhodopsin levels in ameliorating disease phenotype in knockin models for p.Lys154del (c.458-460del) and p.Tyr141Cys (c.422 A > G) in PRPH2. Reducing rhodopsin levels improves physiological function, mitigates the severity of disc abnormalities, and decreases retinal gliosis. Additionally, intravitreal injections of a rhodopsin-specific antisense oligonucleotide successfully enhance the physiological function of photoreceptors and improves the ultrastructure of discs in mutant mice. Presented findings shows that reducing rhodopsin levels is an effective therapeutic strategy for the treatment of inherited retinal degeneration associated with PRPH2 pathogenic variants.
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Affiliation(s)
| | - Mustafa S Makia
- Department of Biomedical Engineering, University of Houston, Houston, TX, 77204, USA
| | - Tylor R Lewis
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Ryan Crane
- Department of Biomedical Engineering, University of Houston, Houston, TX, 77204, USA
| | - Stephanie Zeibak
- Department of Biomedical Engineering, University of Houston, Houston, TX, 77204, USA
| | - Paul Yu
- Department of Biomedical Engineering, University of Houston, Houston, TX, 77204, USA
| | - Mashal Kakakhel
- Department of Biomedical Engineering, University of Houston, Houston, TX, 77204, USA
| | - Carson M Castillo
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Vadim Y Arshavsky
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Muna I Naash
- Department of Biomedical Engineering, University of Houston, Houston, TX, 77204, USA.
| | - Muayyad R Al-Ubaidi
- Department of Biomedical Engineering, University of Houston, Houston, TX, 77204, USA.
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3
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Kaufmann M, Han Z. RPE melanin and its influence on the progression of AMD. Ageing Res Rev 2024; 99:102358. [PMID: 38830546 DOI: 10.1016/j.arr.2024.102358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 05/27/2024] [Indexed: 06/05/2024]
Abstract
OBJECTIVE The aim of this review article is to summarize the latest findings and current understanding of the origin of melanin in the retinal pigment epithelium (RPE), its function within the RPE, its role in the pathogenesis of age-related macular degeneration (AMD), its effect on retinal development, and its potential therapeutic benefit in the treatment of AMD. METHODS A comprehensive search of peer-reviewed journals was conducted using various combinations of key terms such as "melanin," "retinal pigment epithelium" or "RPE," "age-related macular degeneration" or AMD," "lipofuscin," "oxidative stress," and "albinism." Databases searched include PubMed, Scopus, Science Direct, and Google Scholar. 147 papers published between the years of 1957 and 2023 were considered with an emphasis on recent findings. SUMMARY OF FINDINGS AMD is thought to result from chronic oxidative stress within the RPE that results in cellular dysfunction, metabolic dysregulation, inflammation, and lipofuscin accumulation. Melanin functions as a photoscreener, free radical scavenger, and metal cation binding reservoir within the RPE. RPE melanin does not regenerate, and it undergoes degradation over time in response to chronic light exposure and oxidative stress. RPE melanin is important for retinal development and RPE function, and in the aging eye, melanin loss is associated with increased lipid peroxidation, inflammation, and the accumulation of toxic oxidized cellular products. Therefore, melanin-based treatments may serve to preserve RPE and retinal function in AMD. CONCLUSIONS The pathogenesis of AMD is not fully understood, but RPE dysfunction and melanin loss in response to chronic oxidative stress and inflammation are thought to be primary drivers of the disease. Due to melanin's antioxidative effects, melanin-based nanotechnology represents a promising avenue for the treatment of AMD.
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Affiliation(s)
- Mary Kaufmann
- University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Zongchao Han
- Department of Ophthalmology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Division of Pharmacoengineering & Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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Enderlin J, Rieu Q, Réty S, Vanoni EM, Roux S, Dégardin J, César Q, Augustin S, Nous C, Cai B, Fontaine V, Sennlaub F, Nandrot EF. Retinal atrophy, inflammation, phagocytic and metabolic disruptions develop in the MerTK-cleavage-resistant mouse model. Front Neurosci 2024; 18:1256522. [PMID: 38680449 PMCID: PMC11047123 DOI: 10.3389/fnins.2024.1256522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 03/11/2024] [Indexed: 05/01/2024] Open
Abstract
In the eye, cells from the retinal pigment epithelium (RPE) facing the neurosensory retina exert several functions that are all crucial for long-term survival of photoreceptors (PRs) and vision. Among those, RPE cells phagocytose under a circadian rhythm photoreceptor outer segment (POS) tips that are constantly subjected to light rays and oxidative attacks. The MerTK tyrosine kinase receptor is a key element of this phagocytic machinery required for POS internalization. Recently, we showed that MerTK is subjected to the cleavage of its extracellular domain to finely control its function. In addition, monocytes in retinal blood vessels can migrate inside the inner retina and differentiate into macrophages expressing MerTK, but their role in this context has not been studied yet. We thus investigated the ocular phenotype of MerTK cleavage-resistant (MerTKCR) mice to understand the relevance of this characteristic on retinal homeostasis at the RPE and macrophage levels. MerTKCR retinae appear to develop and function normally, as observed in retinal sections, by electroretinogram recordings and optokinetic behavioral tests. Monitoring of MerTKCR and control mice between the ages of 3 and 18 months showed the development of large degenerative areas in the central retina as early as 4 months when followed monthly by optical coherence tomography (OCT) plus fundus photography (FP)/autofluorescence (AF) detection but not by OCT alone. The degenerative areas were associated with AF, which seems to be due to infiltrated macrophages, as observed by OCT and histology. MerTKCR RPE primary cultures phagocytosed less POS in vitro, while in vivo, the circadian rhythm of POS phagocytosis was deregulated. Mitochondrial function and energy production were reduced in freshly dissected RPE/choroid tissues at all ages, thus showing a metabolic impairment not present in macrophages. RPE anomalies were detected by electron microscopy, including phagosomes retained in the apical area and vacuoles. Altogether, this new mouse model displays a novel phenotype that could prove useful to understanding the interplay between RPE and PRs in inflammatory retinal degenerations and highlights new roles for MerTK in the regulation of the energetic metabolism and the maintenance of the immune privilege in the retina.
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Affiliation(s)
- Julie Enderlin
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Quentin Rieu
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Salomé Réty
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Elora M. Vanoni
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Solène Roux
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Julie Dégardin
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Quénol César
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Sébastien Augustin
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Caroline Nous
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Bishuang Cai
- Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Valérie Fontaine
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Florian Sennlaub
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Emeline F. Nandrot
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
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Leung M, Steinman J, Li D, Lor A, Gruesen A, Sadah A, van Kuijk FJ, Montezuma SR, Kondkar AA, Radhakrishnan R, Lobo GP. The Logistical Backbone of Photoreceptor Cell Function: Complementary Mechanisms of Dietary Vitamin A Receptors and Rhodopsin Transporters. Int J Mol Sci 2024; 25:4278. [PMID: 38673863 PMCID: PMC11050646 DOI: 10.3390/ijms25084278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 04/02/2024] [Accepted: 04/04/2024] [Indexed: 04/28/2024] Open
Abstract
In this review, we outline our current understanding of the mechanisms involved in the absorption, storage, and transport of dietary vitamin A to the eye, and the trafficking of rhodopsin protein to the photoreceptor outer segments, which encompasses the logistical backbone required for photoreceptor cell function. Two key mechanisms of this process are emphasized in this manuscript: ocular and systemic vitamin A membrane transporters, and rhodopsin transporters. Understanding the complementary mechanisms responsible for the generation and proper transport of the retinylidene protein to the photoreceptor outer segment will eventually shed light on the importance of genes encoded by these proteins, and their relationship on normal visual function and in the pathophysiology of retinal degenerative diseases.
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Affiliation(s)
- Matthias Leung
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Jeremy Steinman
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Dorothy Li
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Anjelynt Lor
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Andrew Gruesen
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Ahmed Sadah
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Frederik J. van Kuijk
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Sandra R. Montezuma
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Altaf A. Kondkar
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh 12271, Saudi Arabia;
| | - Rakesh Radhakrishnan
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Glenn P. Lobo
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
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6
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Messner A, Aranha dos Santos V, Puchner S, Stegmann H, Schlatter A, Schmidl D, Leitgeb R, Schmetterer L, Werkmeister RM. The Impact of Photopigment Bleaching on the Human Rod Photoreceptor Subretinal Space Measured Via Optical Coherence Tomography. Invest Ophthalmol Vis Sci 2024; 65:20. [PMID: 38470325 PMCID: PMC10941995 DOI: 10.1167/iovs.65.3.20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 02/27/2024] [Indexed: 03/13/2024] Open
Abstract
Purpose The purpose of this study was to investigate rod photopigment bleaching-driven intrinsic optical signals (IOS) in the human outer retina and its measurement repeatability based on a commercial optical coherence tomography (OCT) platform. Methods The optical path length of the rod photoreceptor subretinal space (SRS), that is, the distance between signal bands of rod outer segment tips and retinal pigment epithelium, was measured in 15 healthy subjects in ambient light and during a long-duration bleaching white-light exposure. Results On 2 identical study days (day 1 and day 2 [D1 and D2]), light stimulation resulted in a significant decrease in rod SRS by 21.3 ± 7.6% and 19.8 ± 8.5% (both P < 0.001), respectively. The test-retest reliability of the SRS maximum change of an individual subject was moderate for single measures (intraclass correlation coefficient [ICC] = 0.730, 95% confidence interval [CI] = 0.376, 0.900, P < 0.001) and good for average measures (ICC = 0.844, 95% CI = 0.546, 0.947, P < 0.001). The mean area under the stimulus response curve with values of 14.8 ± 9.4 and 15.5 ± 7.5 µm × minutes (P = 0.782) showed excellent agreement between the stimulus response on D1 and D2. Intermittent dark adaptation of the retina led to an initial increase of the SRS by 6.1% (P = 0.018) and thereafter showed a decrease toward baseline, despite continued dark adaptation. Conclusions The data indicate the potential of commercial OCT in measuring slow IOS in the outer retina suggesting that the rod SRS could serve as a biomarker for photoreceptor function. The presented approach could provide an easily implementable clinical tool for the early detection of diseases affecting photoreceptor health.
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Affiliation(s)
- Alina Messner
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
- Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | | | - Stefan Puchner
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Hannes Stegmann
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Andreas Schlatter
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
- Vienna Institute for Research in Ocular Surgery (VIROS), Department of Ophthalmology, Hanusch Hospital, Vienna, Austria
| | - Doreen Schmidl
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Rainer Leitgeb
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Leopold Schmetterer
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
- Singapore Eye Research Institute, The Academia, Singapore, Singapore
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore, Singapore
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore, Singapore
- Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore
| | - René M. Werkmeister
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
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Yalaz C, Bridges E, Alham NK, Zois CE, Chen J, Bensaad K, Miar A, Pires E, Muschel RJ, McCullagh JSO, Harris AL. Cone photoreceptor phosphodiesterase PDE6H inhibition regulates cancer cell growth and metabolism, replicating the dark retina response. Cancer Metab 2024; 12:5. [PMID: 38350962 PMCID: PMC10863171 DOI: 10.1186/s40170-023-00326-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 11/24/2023] [Indexed: 02/15/2024] Open
Abstract
BACKGROUND PDE6H encodes PDE6γ', the inhibitory subunit of the cGMP-specific phosphodiesterase 6 in cone photoreceptors. Inhibition of PDE6, which has been widely studied for its role in light transduction, increases cGMP levels. The purpose of this study is to characterise the role of PDE6H in cancer cell growth. METHODS From an siRNA screen for 487 genes involved in metabolism, PDE6H was identified as a controller of cell cycle progression in HCT116 cells. Role of PDE6H in cancer cell growth and metabolism was studied through the effects of its depletion on levels of cell cycle controllers, mTOR effectors, metabolite levels, and metabolic energy assays. Effect of PDE6H deletion on tumour growth was also studied in a xenograft model. RESULTS PDE6H knockout resulted in an increase of intracellular cGMP levels, as well as changes to the levels of nucleotides and key energy metabolism intermediates. PDE6H knockdown induced G1 cell cycle arrest and cell death and reduced mTORC1 signalling in cancer cell lines. Both knockdown and knockout of PDE6H resulted in the suppression of mitochondrial function. HCT116 xenografts revealed that PDE6H deletion, as well as treatment with the PDE5/6 inhibitor sildenafil, slowed down tumour growth and improved survival, while sildenafil treatment did not have an additive effect on slowing the growth of PDE6γ'-deficient tumours. CONCLUSIONS Our results indicate that the changes in cGMP and purine pools, as well as mitochondrial function which is observed upon PDE6γ' depletion, are independent of the PKG pathway. We show that in HCT116, PDE6H deletion replicates many effects of the dark retina response and identify PDE6H as a new target in preventing cancer cell proliferation and tumour growth.
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Affiliation(s)
- Ceren Yalaz
- Molecular Oncology Laboratories, Department of Medical Oncology, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK.
| | - Esther Bridges
- Molecular Oncology Laboratories, Department of Medical Oncology, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Nasullah K Alham
- Department of Engineering Science, Institute of Biomedical Engineering (IBME), University of Oxford, Old Road Campus Research Building, Oxford, OX3 7DQ, UK
| | - Christos E Zois
- Molecular Oncology Laboratories, Department of Medical Oncology, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Jianzhou Chen
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Oxford, OX3 7DQ, UK
| | - Karim Bensaad
- Molecular Oncology Laboratories, Department of Medical Oncology, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Ana Miar
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Oxford, OX3 7DQ, UK
| | - Elisabete Pires
- Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
| | - Ruth J Muschel
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Oxford, OX3 7DQ, UK
| | - James S O McCullagh
- Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
| | - Adrian L Harris
- Molecular Oncology Laboratories, Department of Medical Oncology, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
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Lindell M, Kar D, Sedova A, Kim YJ, Packer OS, Schmidt-Erfurth U, Sloan KR, Marsh M, Dacey DM, Curcio CA, Pollreisz A. Volumetric Reconstruction of a Human Retinal Pigment Epithelial Cell Reveals Specialized Membranes and Polarized Distribution of Organelles. Invest Ophthalmol Vis Sci 2023; 64:35. [PMID: 38133501 PMCID: PMC10746928 DOI: 10.1167/iovs.64.15.35] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 11/04/2023] [Indexed: 12/23/2023] Open
Abstract
Purpose Despite the centrality of the retinal pigment epithelium (RPE) in vision and retinopathy our picture of RPE morphology is incomplete. With a volumetric reconstruction of human RPE ultrastructure, we aim to characterize major membranous features including apical processes and their interactions with photoreceptor outer segments, basolateral infoldings, and the distribution of intracellular organelles. Methods A parafoveal retinal sample was acquired from a 21-year-old male organ donor. With serial block-face scanning electron microscopy, a tissue volume from the inner-outer segment junction to basal RPE was captured. Surface membranes and complete internal ultrastructure of an individual RPE cell were achieved with a combination of manual and automated segmentation methods. Results In one RPE cell, apical processes constitute 69% of the total cell surface area, through a dense network of over 3000 terminal branches. Single processes contact several photoreceptors. Basolateral infoldings facing the choriocapillaris resemble elongated filopodia and comprise 22% of the cell surface area. Membranous tubules and sacs of endoplasmic reticulum represent 20% of the cell body volume. A dense basal layer of mitochondria extends apically to partly overlap electron-dense pigment granules. Pores in the nuclear envelope form a distinct pattern of rows aligned with chromatin. Conclusions Specialized membranes at the apical and basal side of the RPE cell body involved in intercellular uptake and transport represent over 90% of the total surface area. Together with the polarized distribution of organelles within the cell body, these findings are relevant for retinal clinical imaging, therapeutic approaches, and disease pathomechanisms.
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Affiliation(s)
- Maximilian Lindell
- Department of Ophthalmology, Medical University of Vienna, Vienna, Austria
| | - Deepayan Kar
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Aleksandra Sedova
- Department of Ophthalmology, Medical University of Vienna, Vienna, Austria
| | - Yeon Jin Kim
- Department of Biological Structure, University of Washington, Seattle, Washington, United States
| | - Orin S. Packer
- Department of Biological Structure, University of Washington, Seattle, Washington, United States
| | | | - Kenneth R. Sloan
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Mike Marsh
- Object Research Systems, Montreal, Quebec, Canada
| | - Dennis M. Dacey
- Department of Biological Structure, University of Washington, Seattle, Washington, United States
| | - Christine A. Curcio
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Andreas Pollreisz
- Department of Ophthalmology, Medical University of Vienna, Vienna, Austria
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9
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Boya P, Kaarniranta K, Handa JT, Sinha D. Lysosomes in retinal health and disease. Trends Neurosci 2023; 46:1067-1082. [PMID: 37848361 PMCID: PMC10842632 DOI: 10.1016/j.tins.2023.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 09/06/2023] [Accepted: 09/24/2023] [Indexed: 10/19/2023]
Abstract
Lysosomes play crucial roles in various cellular processes - including endocytosis, phagocytosis, and autophagy - which are vital for maintaining retinal health. Moreover, these organelles serve as environmental sensors and act as central hubs for multiple signaling pathways. Through communication with other cellular components, such as mitochondria, lysosomes orchestrate the cytoprotective response essential for preserving cellular homeostasis. This coordination is particularly critical in the retina, given its high metabolic rate and susceptibility to photo-oxidative stress. Consequently, impaired lysosomal function and dysregulated communication between lysosomes and other organelles contribute significantly to the pathobiology of major retinal degenerative diseases. This review explores the pivotal role of lysosomes in retinal cells and their involvement in retinal degenerative diseases.
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Affiliation(s)
- Patricia Boya
- Department of Neuroscience, University of Fribourg, Fribourg, Switzerland
| | - Kai Kaarniranta
- Department of Ophthalmology, University of Eastern Finland, Kuopio, Finland; Department of Ophthalmology, Kuopio University Hospital, Kuopio, Finland; Department of Molecular Genetics, University of Lodz, Lodz, Poland
| | - James T Handa
- The Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Debasish Sinha
- The Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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10
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Paterson C, Cannon J, Vargis E. The impact of early RPE cell junction loss on VEGF, Ang-2, and TIMP secretion in vitro. Mol Vis 2023; 29:87-101. [PMID: 37859808 PMCID: PMC10584031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 07/14/2023] [Indexed: 10/21/2023] Open
Abstract
Purpose The retinal pigment epithelium (RPE) is an important tissue for maintaining a healthy retina. Retinal pigment epithelial cells help regulate nutrient transport to photoreceptors and are heavily pigmented to prevent light scattering. These cells also have junction proteins to form monolayers. Monolayers are key players in pathologies such as age-related macular degeneration (AMD), a leading cause of vision loss in older adults. During AMD, RPE cell detachment can occur, resulting in a loss of junctions. Losing junctions can increase the expression of pro-angiogenic vascular endothelial growth factor (VEGF). This overexpression can cause abnormal blood vessel growth or angiogenesis in the retina. Age-related macular degeneration treatments target VEGF to slow angiogenesis progression. However, other proteins, such as angiopoietin-2 (Ang-2) and the tissue inhibitor of metalloproteinase-1 (TIMP-1), may also play important roles, making them potential targets for treatment. Controlling RPE junction formation will help elucidate the relationship between RPE cell detachment and additional angiogenic factor secretion, lead to more therapeutics, and increase the efficacy of current treatments. Methods Micropatterning was used to control the spatial arrangement of primary porcine RPE cells using polydimethylsiloxane (PDMS) stencils. Patterns were formed into PDMS stencils to mimic 10%, 25%, and 50% overall detachment of the RPE monolayer. Zonula-occludens-1 (ZO-1), Ang-2, and VEGF were visualized using immunocytochemical (ICC) staining. An enzyme-linked immunosorbent assay (ELISA) was used to quantify extracellular Ang-2, VEGF, TIMP-1, and TIMP-2 levels. A rod outer segment (OS) phagocytosis assay was performed to determine how RPE junction loss directly affects photoreceptor support. Results The growth of primary porcine RPE cells was successfully controlled using stencils. Morphological changes and a decrease in pigmentation were observed, showing a decline in barrier and light absorption functions as degeneration increased. One day after stencil removal, junction proteins were delocalized, and angiogenic factor secretions were correlated with increased levels of detachment. Secretion levels of Ang-2 and TIMP-1 were significantly increased, whereas VEGF and TIMP-2 concentrations were not as affected by varying levels of detachment. OS phagocytosis appeared lower in RPE cells when ZO-1 was affected. Conclusions These results suggest a correlation between loss of junctions, abnormal angiogenic protein secretion, and reduced OS phagocytosis. Furthermore, Ang-2 and TIMP-1 proteins might be beneficial targets for AMD treatments, and their roles in retinal diseases deserve further investigation.
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Affiliation(s)
- Chase Paterson
- Utah State University, Biological Engineering, Logan, UT
| | - Jamen Cannon
- Utah State University, Biological Engineering, Logan, UT
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11
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Abstract
The human retina is amenable to direct, noninvasive visualization using a wide array of imaging modalities. In the ∼140 years since the publication of the first image of the living human retina, there has been a continued evolution of retinal imaging technology. Advances in image acquisition and processing speed now allow real-time visualization of retinal structure, which has revolutionized the diagnosis and management of eye disease. Enormous advances have come in image resolution, with adaptive optics (AO)-based systems capable of imaging the retina with single-cell resolution. In addition, newer functional imaging techniques provide the ability to assess function with exquisite spatial and temporal resolution. These imaging advances have had an especially profound impact on the field of inherited retinal disease research. Here we will review some of the advances and applications of AO retinal imaging in patients with inherited retinal disease.
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Affiliation(s)
- Jacque L Duncan
- Department of Ophthalmology, University of California, San Francisco, California 94143-4081, USA
| | - Joseph Carroll
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin Eye Institute, Milwaukee, Wisconsin 53226, USA
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12
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Lou L, Ostrin LA. The outdoor environment affects retinal and choroidal thickness. Ophthalmic Physiol Opt 2023; 43:572-583. [PMID: 36779486 PMCID: PMC10081136 DOI: 10.1111/opo.13107] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 01/27/2023] [Accepted: 01/28/2023] [Indexed: 02/14/2023]
Abstract
PURPOSE Accumulating evidence suggests that time outdoors is protective against myopia development and that the choroid may be involved in this effect. The goal of this study was to examine the effect of 2 h of time outdoors in sunlight on retinal and choroidal thickness in adults. METHODS Twenty adults, ages 23-46 years, each participated in three experimental sessions on different days, consisting of 2 h of exposure to (1) indoor illumination (350 lux), (2) darkness (<0.1 lux) or (3) outdoor environment (6000-50,000 lux). Spectral-domain optical coherence tomography (SD-OCT) imaging was conducted at baseline, after 1 and 2 h of exposure, and after 1 and 2 h of follow-up. Choroidal, total retinal, photoreceptor outer segment + retinal pigment epithelium (RPE) and photoreceptor inner segment thicknesses were determined. RESULTS At 2 h, the choroid was significantly thinner during the outdoor compared with the indoor and dark conditions (p < 0.01) but was not significantly different at follow-up. Total retinal thickness was significantly thicker during and after the outdoor compared with the indoor and dark conditions. The outer segment + RPE was significantly thinner during the outdoor compared with the indoor condition but was not significantly different at follow-up. The inner segment was significantly thicker during the outdoor compared with the indoor and dark conditions during exposure and follow-up. CONCLUSIONS Spending 2 h outdoors under high-intensity sunlight resulted in an unexpected thinning of the choroid, which recovered post-exposure. Retinal thickness showed different responses to the outdoor and indoor environments and was sensitive to the duration of exposure.
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Affiliation(s)
- Linjiang Lou
- College of Optometry, University of Houston, Houston, Texas, USA
| | - Lisa A. Ostrin
- College of Optometry, University of Houston, Houston, Texas, USA
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13
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Optical coherence tomography in healthy human subjects in the setting of prolonged dark adaptation. Sci Rep 2023; 13:3725. [PMID: 36879027 PMCID: PMC9988879 DOI: 10.1038/s41598-023-30747-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 02/28/2023] [Indexed: 03/08/2023] Open
Abstract
Human studies have established that short periods of dark adaptation can induce outer retinal thinning and various band intensity changes that can be detected with Optical Coherence Tomography (OCT). Similar findings were observed in mice, including a positive correlation between the degree of outer retinal changes and dark adaptation duration. We decided to assess potential retinal structural changes following prolonged dark adaptation in humans. 40 healthy subjects without any ocular diseases participated in this study. For each subject, one eye was covered for dark adaptation for four hours, and the other eye was left uncovered as a control. Before and after the dark adaptation period, both eyes were assessed with OCT. Using the Heidelberg Spectralis system, basic statistical functions, and qualitative and quantitative analysis, we were able to compare retinal layer thicknesses and band intensities between covered (dark adapted) versus uncovered (control) eyes. Prolonged dark adaptation did not induce any significant thickness, volume, or intensity changes in the outer retina or in the inner or overall retina. These observations thus alter our current understanding of the mechanisms underlying dark adaptation's neuroprotective effects in preventing blindness and require further study.
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14
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Williams DR, Burns SA, Miller DT, Roorda A. Evolution of adaptive optics retinal imaging [Invited]. BIOMEDICAL OPTICS EXPRESS 2023; 14:1307-1338. [PMID: 36950228 PMCID: PMC10026580 DOI: 10.1364/boe.485371] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 02/02/2023] [Indexed: 05/02/2023]
Abstract
This review describes the progress that has been achieved since adaptive optics (AO) was incorporated into the ophthalmoscope a quarter of a century ago, transforming our ability to image the retina at a cellular spatial scale inside the living eye. The review starts with a comprehensive tabulation of AO papers in the field and then describes the technological advances that have occurred, notably through combining AO with other imaging modalities including confocal, fluorescence, phase contrast, and optical coherence tomography. These advances have made possible many scientific discoveries from the first maps of the topography of the trichromatic cone mosaic to exquisitely sensitive measures of optical and structural changes in photoreceptors in response to light. The future evolution of this technology is poised to offer an increasing array of tools to measure and monitor in vivo retinal structure and function with improved resolution and control.
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Affiliation(s)
- David R. Williams
- The Institute of Optics and the Center for
Visual Science, University of Rochester,
Rochester NY, USA
| | - Stephen A. Burns
- School of Optometry, Indiana
University at Bloomington, Bloomington IN, USA
| | - Donald T. Miller
- School of Optometry, Indiana
University at Bloomington, Bloomington IN, USA
| | - Austin Roorda
- Herbert Wertheim School of Optometry and
Vision Science, University of California at Berkeley, Berkeley CA, USA
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15
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Paniagua AE, Sabharwal HS, Kethu K, Chang AW, Williams DS. Revisiting the Daily Timing of POS Phagocytosis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1415:515-519. [PMID: 37440080 DOI: 10.1007/978-3-031-27681-1_75] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Retinal pigment epithelium (RPE) cells daily ingest the tips of the photoreceptor outer segments (POSs), with phagosome number varying throughout a 24-h cycle. A major focus in the literature has been on a peak in phagosome concentration shortly after lights-on. Moreover, this peak has frequently been inferred to represent a peak in POS tip ingestion. Here, we have reviewed old and new literature on the daily cycle of phagosome number in the RPE and conclude that there is more variation in the timing of phagosome concentration peaks than is currently acknowledged. We also discuss that phagosome quantity is affected by the rate of phagosome degradation as well as the rate of ingestion; given that phagosome half-life may not be constant throughout the daily cycle, maximal POS ingestion may not necessarily coincide with a peak in phagosome concentration.
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Affiliation(s)
- Antonio E Paniagua
- Departments of Ophthalmology and Neurobiology, Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
| | - Harjas S Sabharwal
- Departments of Ophthalmology and Neurobiology, Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Kausalya Kethu
- Departments of Ophthalmology and Neurobiology, Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Andrew W Chang
- Departments of Ophthalmology and Neurobiology, Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - David S Williams
- Departments of Ophthalmology and Neurobiology, Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
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16
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Pandiyan VP, Schleufer S, Slezak E, Fong J, Upadhyay R, Roorda A, Ng R, Sabesan R. Characterizing cone spectral classification by optoretinography. BIOMEDICAL OPTICS EXPRESS 2022; 13:6574-6594. [PMID: 36589563 PMCID: PMC9774847 DOI: 10.1364/boe.473608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 10/26/2022] [Accepted: 10/27/2022] [Indexed: 05/02/2023]
Abstract
Light propagation in photoreceptor outer segments is affected by photopigment absorption and the phototransduction amplification cascade. Photopigment absorption has been studied using retinal densitometry, while recently, optoretinography (ORG) has provided an avenue to probe changes in outer segment optical path length due to phototransduction. With adaptive optics (AO), both densitometry and ORG have been used for cone spectral classification based on the differential bleaching signatures of the three cone types. Here, we characterize cone classification by ORG, implemented in an AO line-scan optical coherence tomography (OCT), and compare it against densitometry. The cone mosaics of five color normal subjects were classified using ORG showing high probability (∼0.99), low error (<0.22%), high test-retest reliability (∼97%), and short imaging durations (< 1 hour). Of these, the cone spectral assignments in two subjects were compared against AO-scanning laser opthalmoscope densitometry. High agreement (mean: 91%) was observed between the two modalities in these two subjects, with measurements conducted 6-7 years apart. Overall, ORG benefits from higher sensitivity and dynamic range to probe cone photopigments compared to densitometry, and thus provides greater fidelity for cone spectral classification.
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Affiliation(s)
- Vimal Prabhu Pandiyan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
| | - Sierra Schleufer
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
| | - Emily Slezak
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
| | - James Fong
- Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
| | - Rishi Upadhyay
- Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
| | - Austin Roorda
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, Berkeley, CA, USA
| | - Ren Ng
- Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
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17
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Berkowitz BA, Podolsky RH, Childers KL, Roberts R, Katz R, Waseem R, Robbings BM, Hass DT, Hurley JB, Sweet IR, Goodman C, Qian H, Alvisio B, Heaps S. Transducin-Deficient Rod Photoreceptors Evaluated With Optical Coherence Tomography and Oxygen Consumption Rate Energy Biomarkers. Invest Ophthalmol Vis Sci 2022; 63:22. [PMID: 36576748 PMCID: PMC9804021 DOI: 10.1167/iovs.63.13.22] [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: 12/29/2022] Open
Abstract
Purpose To test the hypothesis that rod energy biomarkers in light and dark are similar in mice without functional rod transducin (Gnat1rd17). Methods Gnat1rd17 and wildtype (WT) mice were studied in canonically low energy demand (light) and high energy demand (dark) conditions. We measured rod inner segment ellipsoid zone (ISez) profile shape, external limiting membrane-retinal pigment epithelium (ELM-RPE) thickness, and magnitude of a hyporeflective band (HB) intensity dip located between photoreceptor tips and apical RPE; antioxidants were given in a subset of mice. Oxygen consumption rate (OCR) and visual performance indexes were also measured. Results The lower energy demand expected in light-adapted wildtype retinas was associated with an elongated ISez, thicker ELM-RPE, and higher HB magnitude, and lower OCR compared to high energy demand conditions in the dark. Gnat1rd17 mice showed a wildtype-like ISez profile shape at 20 minutes of light that became rounder at 60 minutes; at both times, ELM-RPE was smaller than wildtype values, and the HB magnitude was unmeasurable. OCR was higher than in the dark. Light-adapted Gnat1rd17 mice biomarkers were unaffected by anti-oxidants. Gnat1rd17 mice showed modest outer nuclear layer thinning and no reduction in visual performance indexes. Conclusions Light-stimulated changes in all biomarkers in WT mice are consistent with the established light-induced decrease in net energy demand. In contrast, biomarker changes in Gnat1rd17 mice raise the possibility that light increases net energy demand in the absence of rod phototransduction.
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Affiliation(s)
- Bruce A Berkowitz
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Robert H Podolsky
- Biostatistics and Study Methodology, Children's National Hospital, Silver Spring, Maryland, United States
| | - Karen Lins Childers
- Beaumont Research Institute, Beaumont Health, Royal Oak, Michigan, United States
| | - Robin Roberts
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Ryan Katz
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Rida Waseem
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Brian M Robbings
- Department of Biochemistry, Department of Ophthalmology, University of Washington, Seattle, Washington, United States.,Department of Medicine, UW Medicine Diabetes Institute, University of Washington, Seattle, Washington, United States
| | - Daniel T Hass
- Department of Biochemistry, Department of Ophthalmology, University of Washington, Seattle, Washington, United States
| | - James B Hurley
- Department of Biochemistry, Department of Ophthalmology, University of Washington, Seattle, Washington, United States
| | - Ian R Sweet
- Department of Medicine, UW Medicine Diabetes Institute, University of Washington, Seattle, Washington, United States
| | - Cole Goodman
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Haohua Qian
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Bruno Alvisio
- OSIO Bioinformatics Core, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Sam Heaps
- OSIO Bioinformatics Core, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
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18
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Warner RL, Brainard DH, Morgan JIW. Repeatability and reciprocity of the cone optoretinogram. BIOMEDICAL OPTICS EXPRESS 2022; 13:6561-6573. [PMID: 36589578 PMCID: PMC9774868 DOI: 10.1364/boe.471990] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 11/08/2022] [Accepted: 11/08/2022] [Indexed: 05/02/2023]
Abstract
Optoretinography has enabled noninvasive visualization of physiological changes in cone photoreceptors exposed to light. Understanding the cone optoretinogram in healthy subjects is essential for establishing it as a biomarker for cone function in disease. Here, we measure the population cone intensity optoretinogram in healthy adults, for multiple irradiance/duration combinations of visible stimuli with equal energy. We study the within and between session repeatability and reciprocity of the ORG in five healthy subjects. We find the cone optoretinogram exhibits equivalent amplitudes for equal-energy stimuli. We also find good within-subject repeatability, which allows us to show differences across the five subjects.
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Affiliation(s)
- R. L. Warner
- Scheie Eye Institute, Department of
Ophthalmology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - D. H. Brainard
- Psychology Department, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - J. I. W. Morgan
- Scheie Eye Institute, Department of
Ophthalmology, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Center for Advanced Retinal and Ocular
Therapeutics, University of Pennsylvania,
Philadelphia, PA, 19104, USA
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19
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Mozaffari S, Feroldi F, LaRocca F, Tiruveedhula P, Gregory PD, Park BH, Roorda A. Retinal imaging using adaptive optics optical coherence tomography with fast and accurate real-time tracking. BIOMEDICAL OPTICS EXPRESS 2022; 13:5909-5925. [PMID: 36733754 PMCID: PMC9872892 DOI: 10.1364/boe.467634] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 08/11/2022] [Accepted: 10/04/2022] [Indexed: 05/02/2023]
Abstract
One of the main obstacles in high-resolution 3-D retinal imaging is eye motion, which causes blur and distortion artifacts that require extensive post-processing to be corrected. Here, an adaptive optics optical coherence tomography (AOOCT) system with real-time active eye motion correction is presented. Correction of ocular aberrations and of retinal motion is provided by an adaptive optics scanning laser ophthalmoscope (AOSLO) that is optically and electronically combined with the AOOCT system. We describe the system design and quantify its performance. The AOOCT system features an independent focus adjustment that allows focusing on different retinal layers while maintaining the AOSLO focus on the photoreceptor mosaic for high fidelity active motion correction. The use of a high-quality reference frame for eye tracking increases revisitation accuracy between successive imaging sessions, allowing to collect several volumes from the same area. This system enables spatially targeted retinal imaging as well as volume averaging over multiple imaging sessions with minimal correction of motion in post processing.
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Affiliation(s)
- Sanam Mozaffari
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Fabio Feroldi
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Francesco LaRocca
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Pavan Tiruveedhula
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Patrick D. Gregory
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
| | - B. Hyle Park
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
| | - Austin Roorda
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, Berkeley, CA 94720, USA
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20
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Moran AL, Fehilly JD, Floss Jones D, Collery R, Kennedy BN. Regulation of the rhythmic diversity of daily photoreceptor outer segment phagocytosis in vivo. FASEB J 2022; 36:e22556. [PMID: 36165194 PMCID: PMC9828801 DOI: 10.1096/fj.202200990rr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 08/30/2022] [Accepted: 09/06/2022] [Indexed: 01/12/2023]
Abstract
Outer segment phagocytosis (OSP) is a highly-regulated, biological process wherein photoreceptor outer segment (OS) tips are cyclically phagocytosed by the adjacent retinal pigment epithelium (RPE) cells. Often an overlooked retinal process, rhythmic OSP ensures the maintenance of healthy photoreceptors and vision. Daily, the photoreceptors renew OS at their base and the most distal, and likely oldest, OS tips, are phagocytosed by the RPE, preventing the accumulation of photo-oxidative compounds by breaking down phagocytosed OS tips and recycling useful components to the photoreceptors. Light changes often coincide with an escalation of OSP and within hours the phagosomes formed in each RPE cell are resolved. In the last two decades, individual molecular regulators were elucidated. Some of the molecular machinery used by RPE cells for OSP is highly similar to mechanisms used by other phagocytic cells for the clearance of apoptotic cells. Consequently, in the RPE, many molecular regulators of retinal phagocytosis have been elucidated. However, there is still a knowledge gap regarding the key regulators of physiological OSP in vivo between endogenous photoreceptors and the RPE. Understanding the regulation of OSP is of significant clinical interest as age-related macular degeneration (AMD) and inherited retinal diseases (IRD) are linked with altered OSP. Here, we review the in vivo timing of OSP peaks in selected species and focus on the reported in vivo environmental and molecular regulators of OSP.
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Affiliation(s)
- Ailis L. Moran
- UCD School of Biomolecular and Biomedical ScienceUniversity College DublinDublinIreland,UCD Conway InstituteUniversity College DublinDublinIreland
| | - John D. Fehilly
- UCD School of Biomolecular and Biomedical ScienceUniversity College DublinDublinIreland,UCD Conway InstituteUniversity College DublinDublinIreland
| | - Daniel Floss Jones
- UCD School of Biomolecular and Biomedical ScienceUniversity College DublinDublinIreland,UCD Conway InstituteUniversity College DublinDublinIreland
| | - Ross Collery
- Department of Cell Biology, Neurobiology and AnatomyMedical College of WisconsinMilwaukeeWisconsinUSA,Department of Ophthalmology and Visual SciencesMedical College of Wisconsin Eye InstituteMilwaukeeWisconsinUSA
| | - Breandán N. Kennedy
- UCD School of Biomolecular and Biomedical ScienceUniversity College DublinDublinIreland,UCD Conway InstituteUniversity College DublinDublinIreland
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21
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Lou L, Ostrin LA. Effects of Monocular Light Deprivation on the Diurnal Rhythms in Retinal and Choroidal Thickness. Invest Ophthalmol Vis Sci 2022; 63:6. [PMID: 35816044 PMCID: PMC9284467 DOI: 10.1167/iovs.63.8.6] [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 determine the effects of monocular light deprivation on diurnal rhythms in retinal and choroidal thickness. Methods Twenty participants, ages 22 to 45 years, underwent spectral domain optical coherence tomography imaging every three hours, from 8 AM to 8 PM, on two consecutive days. Participants wore an eye patch over the left eye starting at bedtime of day 1 until the end of the last measurement on day 2. Choroidal, total retinal, photoreceptor outer segment + retinal pigment epithelium (RPE), and photoreceptor inner segment thicknesses were determined. Results For both eyes, significant diurnal variations were observed in choroidal, total retinal, outer segment + RPE, and inner segment thickness (P < 0.001). For light-deprived eyes, choroid diurnal variation persisted, although the choroid was significantly thinner at 8 AM and 11 AM (P < 0.01) on day 2 compared to day 1. On the other hand, diurnal variations in retinal thickness were eliminated in the light-deprived eye on day 2 when the eye was patched (P > 0.05). Total retinal and inner segment thicknesses significantly decreased (P < 0.001) and outer segment + RPE thickness significantly increased (P < 0.05) on day 2 compared to day 1. Conclusions Blocking light exposure in one eye abolished the rhythms in retinal thickness, but not in choroidal thickness, of the deprived eye. Findings suggest that the rhythms in retinal thickness are, at least in part, driven by light exposure, whereas the rhythm in choroidal thickness is not impacted by short-term light deprivation.
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Affiliation(s)
- Linjiang Lou
- College of Optometry, University of Houston, Houston, Texas, United States
| | - Lisa A Ostrin
- College of Optometry, University of Houston, Houston, Texas, United States
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22
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Peña JS, Vazquez M. Harnessing the Neuroprotective Behaviors of Müller Glia for Retinal Repair. FRONT BIOSCI-LANDMRK 2022; 27:169. [PMID: 35748245 PMCID: PMC9639582 DOI: 10.31083/j.fbl2706169] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 04/18/2022] [Accepted: 05/05/2022] [Indexed: 11/29/2022]
Abstract
Progressive and irreversible vision loss in mature and aging adults creates a health and economic burden, worldwide. Despite the advancements of many contemporary therapies to restore vision, few approaches have considered the innate benefits of gliosis, the endogenous processes of retinal repair that precede vision loss. Retinal gliosis is fundamentally driven by Müller glia (MG) and is characterized by three primary cellular mechanisms: hypertrophy, proliferation, and migration. In early stages of gliosis, these processes have neuroprotective potential to halt the progression of disease and encourage synaptic activity among neurons. Later stages, however, can lead to glial scarring, which is a hallmark of disease progression and blindness. As a result, the neuroprotective abilities of MG have remained incompletely explored and poorly integrated into current treatment regimens. Bioengineering studies of the intrinsic behaviors of MG hold promise to exploit glial reparative ability, while repressing neuro-disruptive MG responses. In particular, recent in vitro systems have become primary models to analyze individual gliotic processes and provide a stepping stone for in vivo strategies. This review highlights recent studies of MG gliosis seeking to harness MG neuroprotective ability for regeneration using contemporary biotechnologies. We emphasize the importance of studying gliosis as a reparative mechanism, rather than disregarding it as an unfortunate clinical prognosis in diseased retina.
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Affiliation(s)
- Juan S. Peña
- Department of Biomedical Engineering, Rutgers, The State
University of New Jersey, Piscataway (08854), New Jersey, USA
| | - Maribel Vazquez
- Department of Biomedical Engineering, Rutgers, The State
University of New Jersey, Piscataway (08854), New Jersey, USA
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23
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Hanna J, David LA, Touahri Y, Fleming T, Screaton RA, Schuurmans C. Beyond Genetics: The Role of Metabolism in Photoreceptor Survival, Development and Repair. Front Cell Dev Biol 2022; 10:887764. [PMID: 35663397 PMCID: PMC9157592 DOI: 10.3389/fcell.2022.887764] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 04/19/2022] [Indexed: 12/11/2022] Open
Abstract
Vision commences in the retina with rod and cone photoreceptors that detect and convert light to electrical signals. The irreversible loss of photoreceptors due to neurodegenerative disease leads to visual impairment and blindness. Interventions now in development include transplanting photoreceptors, committed photoreceptor precursors, or retinal pigment epithelial (RPE) cells, with the latter protecting photoreceptors from dying. However, introducing exogenous human cells in a clinical setting faces both regulatory and supply chain hurdles. Recent work has shown that abnormalities in central cell metabolism pathways are an underlying feature of most neurodegenerative disorders, including those in the retina. Reversal of key metabolic alterations to drive retinal repair thus represents a novel strategy to treat vision loss based on cell regeneration. Here, we review the connection between photoreceptor degeneration and alterations in cell metabolism, along with new insights into how metabolic reprogramming drives both retinal development and repair following damage. The potential impact of metabolic reprogramming on retinal regeneration is also discussed, specifically in the context of how metabolic switches drive both retinal development and the activation of retinal glial cells known as Müller glia. Müller glia display latent regenerative properties in teleost fish, however, their capacity to regenerate new photoreceptors has been lost in mammals. Thus, re-activating the regenerative properties of Müller glia in mammals represents an exciting new area that integrates research into developmental cues, central metabolism, disease mechanisms, and glial cell biology. In addition, we discuss this work in relation to the latest insights gleaned from other tissues (brain, muscle) and regenerative species (zebrafish).
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Affiliation(s)
- Joseph Hanna
- Sunnybrook Research Institute, Biological Sciences, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada
| | - Luke Ajay David
- Sunnybrook Research Institute, Biological Sciences, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada
| | - Yacine Touahri
- Sunnybrook Research Institute, Biological Sciences, Toronto, ON, Canada
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Taylor Fleming
- Sunnybrook Research Institute, Biological Sciences, Toronto, ON, Canada
| | - Robert A. Screaton
- Sunnybrook Research Institute, Biological Sciences, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Carol Schuurmans
- Sunnybrook Research Institute, Biological Sciences, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
- *Correspondence: Carol Schuurmans,
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24
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Vargas JA, Finnemann SC. Probing Photoreceptor Outer Segment Phagocytosis by the RPE In Vivo: Models and Methodologies. Int J Mol Sci 2022; 23:ijms23073661. [PMID: 35409021 PMCID: PMC8998817 DOI: 10.3390/ijms23073661] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 03/23/2022] [Accepted: 03/24/2022] [Indexed: 01/27/2023] Open
Abstract
In the vertebrate retina, the light-sensitive photoreceptor rods and cones constantly undergo renewal by generating new portions of the outer segment and shedding their distal, spent tips. The neighboring RPE provides the critical function of engulfing the spent material by phagocytosis. RPE phagocytosis of shed rod outer segment fragments is a circadian process that occurs in a burst of activity shortly after daily light onset with low activity at other times, a rhythm that has been reported for many species and over 50 years. In this review, we compare studies on the rhythm and quantity of RPE phagocytosis using different in vivo model systems and assessment methods. We discuss how measurement methodology impacts the observation and analysis of RPE phagocytosis. Published studies on RPE phagocytosis investigating mice further suggest that differences in genetic background and housing conditions may affect results. Altogether, a comparison between RPE phagocytosis studies performed using differing methodology and strains of the same species is not as straightforward as previously thought.
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25
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Kim TH, Ding J, Yao X. Intrinsic signal optoretinography of dark adaptation kinetics. Sci Rep 2022; 12:2475. [PMID: 35169239 PMCID: PMC8847457 DOI: 10.1038/s41598-022-06562-4] [Citation(s) in RCA: 4] [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: 09/02/2021] [Accepted: 02/02/2022] [Indexed: 12/13/2022] Open
Abstract
Delayed dark adaptation due to impaired rod photoreceptor homeostasis has been reported as the earliest symptom of eye diseases such as age-related macular degeneration, diabetic retinopathy, and retinitis pigmentosa. Objective measurement of dark adaptation can facilitate early diagnosis to enable prompt intervention to prevent vision loss. However, there is a lack of noninvasive methods capable of spatiotemporal monitoring of photoreceptor changes during dark adaptation. Here we demonstrate functional optical coherence tomography (OCT) for in vivo intrinsic signal optoretinography (ORG) of dark adaptation kinetics in the C57BL/6J mouse retina. Functional OCT revealed a shortening of the outer retina, a rearrangement of the cone and rod photoreceptor interdigitation zone, and a reduction in intrinsic signal amplitude at the photoreceptor inner segment ellipsoid (ISe). A strong positive correlation between the outer retinal shortening and ISe intensity reduction was also confirmed. Functional OCT of dark adaptation kinetics promises an objective method for rapid ORG assessment of physiological integrity of retinal photoreceptors.
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Affiliation(s)
- Tae-Hoon Kim
- Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Jie Ding
- Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Xincheng Yao
- Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA.
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, 60612, USA.
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26
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Insights into pathological mechanisms and interventions revealed by analyzing a mathematical model for cone metabolism. Biosci Rep 2022; 42:230791. [PMID: 35156683 PMCID: PMC8905305 DOI: 10.1042/bsr20212457] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 01/14/2022] [Accepted: 02/11/2022] [Indexed: 11/17/2022] Open
Abstract
This work analyzes a mathematical model for the metabolic dynamics of a cone photoreceptor, which is the first model to account for energy generation from fatty acids oxidation of shed photoreceptor outer segments (POS). Multiple parameter bifurcation analysis shows that joint variations in external glucose, the efficiency of glucose transporter 1 (GLUT1), lipid utilization for POS renewal, and oxidation of fatty acids affect the cone’s metabolic vitality and its capability to adapt under glucose-deficient conditions. The analysis further reveals that when glucose is scarce, cone viability cannot be sustained by only fueling energy production in the mitochondria, but it also requires supporting anabolic processes to create lipids necessary for cell maintenance and repair. In silico experiments are used to investigate how the duration of glucose deprivation impacts the cell without and with a potential GLUT1 or oxidation of fatty acids intervention as well as a dual intervention. The results show that for prolonged duration of glucose deprivation, the cone metabolic system does not recover with higher oxidation of fatty acids and requires greater effectiveness of GLUT1 to recover. Finally, time-varying global sensitivity analysis (GSA) is applied to assess the sensitivity of the model outputs of interest to changes and uncertainty in the parameters at specific times. The results reveal a critical temporal window where there would be more flexibility for interventions to rescue a cone cell from the detrimental consequences of glucose shortage.
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27
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Roberts PA. Mathematical Models of Retinitis Pigmentosa: The Trophic Factor Hypothesis. J Theor Biol 2021; 534:110938. [PMID: 34687673 DOI: 10.1016/j.jtbi.2021.110938] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 10/02/2021] [Accepted: 10/04/2021] [Indexed: 10/20/2022]
Abstract
Retinitis pigmentosa (RP) is the term used to denote a group of inherited retinal-degenerative conditions that cause progressive sight loss. Individuals with this condition lose their light-sensitive photoreceptor cells, known as rods and cones, over a period of years to decades; degeneration starting in the retinal periphery, and spreading peripherally and centrally over time. RP is a rod-cone dystrophy, meaning that rod health and function are affected earlier and more severely than that of cones. Rods degenerate due to an underlying mutation, whereas the reasons for cone degeneration are unknown. A number of mechanisms have been proposed to explain secondary cone loss and the spatio-temporal patterns of retinal degeneration in RP. One of the most promising is the trophic factor hypothesis, which suggests that rods produce a factor necessary for cone survival, such that, when rods degenerate, cone degeneration follows. In this paper we formulate and analyse mathematical models of human RP under the trophic factor hypothesis. These models are constructed as systems of reaction-diffusion partial differential equations in one spatial dimension, and are solved and analysed using a combination of numerical and analytical methods. We predict the conditions under which cones will degenerate following the loss of a patch of rods from the retina, the critical trophic factor treatment rate required to prevent cone degeneration following rod loss and the spatio-temporal patterns of cone loss that would result if the trophic factor mechanism alone were responsible for retinal degeneration.
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Affiliation(s)
- Paul A Roberts
- School of Life Sciences, University of Sussex, John Maynard Smith Building, Brighton BN1 9QG, UK.
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28
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Afanasyeva TAV, Corral-Serrano JC, Garanto A, Roepman R, Cheetham ME, Collin RWJ. A look into retinal organoids: methods, analytical techniques, and applications. Cell Mol Life Sci 2021; 78:6505-6532. [PMID: 34420069 PMCID: PMC8558279 DOI: 10.1007/s00018-021-03917-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 07/14/2021] [Accepted: 08/09/2021] [Indexed: 12/15/2022]
Abstract
Inherited retinal diseases (IRDs) cause progressive loss of light-sensitive photoreceptors in the eye and can lead to blindness. Gene-based therapies for IRDs have shown remarkable progress in the past decade, but the vast majority of forms remain untreatable. In the era of personalised medicine, induced pluripotent stem cells (iPSCs) emerge as a valuable system for cell replacement and to model IRD because they retain the specific patient genome and can differentiate into any adult cell type. Three-dimensional (3D) iPSCs-derived retina-like tissue called retinal organoid contains all major retina-specific cell types: amacrine, bipolar, horizontal, retinal ganglion cells, Müller glia, as well as rod and cone photoreceptors. Here, we describe the main applications of retinal organoids and provide a comprehensive overview of the state-of-art analysis methods that apply to this model system. Finally, we will discuss the outlook for improvements that would bring the cellular model a step closer to become an established system in research and treatment development of IRDs.
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Affiliation(s)
- Tess A V Afanasyeva
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein 10, 6525 GA, Nijmegen, The Netherlands
| | | | - Alejandro Garanto
- Department of Pediatrics, Amalia Children's Hospital and Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Human Genetics and Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ronald Roepman
- Department of Human Genetics and Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Michael E Cheetham
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK.
| | - Rob W J Collin
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein 10, 6525 GA, Nijmegen, The Netherlands.
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29
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Gautam P, Hamashima K, Chen Y, Zeng Y, Makovoz B, Parikh BH, Lee HY, Lau KA, Su X, Wong RCB, Chan WK, Li H, Blenkinsop TA, Loh YH. Multi-species single-cell transcriptomic analysis of ocular compartment regulons. Nat Commun 2021; 12:5675. [PMID: 34584087 PMCID: PMC8478974 DOI: 10.1038/s41467-021-25968-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 09/07/2021] [Indexed: 11/23/2022] Open
Abstract
The retina is a widely profiled tissue in multiple species by single-cell RNA sequencing studies. However, integrative research of the retina across species is lacking. Here, we construct the first single-cell atlas of the human and porcine ocular compartments and study inter-species differences in the retina. In addition to that, we identify putative adult stem cells present in the iris tissue. We also create a disease map of genes involved in eye disorders across compartments of the eye. Furthermore, we probe the regulons of different cell populations, which include transcription factors and receptor-ligand interactions and reveal unique directional signalling between ocular cell types. In addition, we study conservation of regulons across vertebrates and zebrafish to identify common core factors. Here, we show perturbation of KLF7 gene expression during retinal ganglion cells differentiation and conclude that it plays a significant role in the maturation of retinal ganglion cells. A comprehensive analysis of the ocular networks among various tissues is necessary to understand eye physiology in health and disease. Here the authors present a multi-species single-cell transcriptomic atlas consisting of cells of the cornea, iris, ciliary body, neural retina, retinal pigmented epithelium, and choroid.
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Affiliation(s)
- Pradeep Gautam
- Cell Fate Engineering and Therapeutics Laboratory, A*STAR Institute of Molecular and Cell Biology, Singapore, 138673, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore
| | - Kiyofumi Hamashima
- Cell Fate Engineering and Therapeutics Laboratory, A*STAR Institute of Molecular and Cell Biology, Singapore, 138673, Singapore
| | - Ying Chen
- Cell Fate Engineering and Therapeutics Laboratory, A*STAR Institute of Molecular and Cell Biology, Singapore, 138673, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore.,Integrative Sciences and Engineering Programme (ISEP), NUS Graduate School, National University of Singapore, 21 Lower Kent Ridge Road, Singapore, 119077, Singapore
| | - Yingying Zeng
- Cell Fate Engineering and Therapeutics Laboratory, A*STAR Institute of Molecular and Cell Biology, Singapore, 138673, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore
| | - Bar Makovoz
- Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Bhav Harshad Parikh
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Translational Retinal Research Laboratory, A*STAR Institute of Molecular and Cell Biology, Singapore, 138673, Singapore
| | - Hsin Yee Lee
- Cell Fate Engineering and Therapeutics Laboratory, A*STAR Institute of Molecular and Cell Biology, Singapore, 138673, Singapore
| | - Katherine Anne Lau
- Cell Fate Engineering and Therapeutics Laboratory, A*STAR Institute of Molecular and Cell Biology, Singapore, 138673, Singapore
| | - Xinyi Su
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Translational Retinal Research Laboratory, A*STAR Institute of Molecular and Cell Biology, Singapore, 138673, Singapore.,Singapore Eye Research Institute, 11 Third Hospital Avenue, Singapore, 168751, Singapore
| | - Raymond C B Wong
- Centre for Eye Research Australia, Melbourne, Vic, Australia.,Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, Vic, Australia.,Shenzhen Eye Hospital, Shenzhen University School of Medicine, Shenzhen, China
| | - Woon-Khiong Chan
- Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore.,Integrative Sciences and Engineering Programme (ISEP), NUS Graduate School, National University of Singapore, 21 Lower Kent Ridge Road, Singapore, 119077, Singapore
| | - Hu Li
- Center for Individualized Medicine, Department of Molecular Pharmacology & Experimental Therapeutics, Mayo Clinic, Rochester, MN, 55905, USA.
| | | | - Yuin-Han Loh
- Cell Fate Engineering and Therapeutics Laboratory, A*STAR Institute of Molecular and Cell Biology, Singapore, 138673, Singapore. .,Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore. .,Integrative Sciences and Engineering Programme (ISEP), NUS Graduate School, National University of Singapore, 21 Lower Kent Ridge Road, Singapore, 119077, Singapore. .,Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117593, Singapore.
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30
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Jonnal RS. Toward a clinical optoretinogram: a review of noninvasive, optical tests of retinal neural function. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1270. [PMID: 34532407 PMCID: PMC8421939 DOI: 10.21037/atm-20-6440] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 07/12/2021] [Indexed: 11/17/2022]
Abstract
The past few years have witnessed rapid development of the optoretinogram—a noninvasive, optical measurement of neural function in the retina, and especially the photoreceptors (Ph). While its recent development has been rapid, it represents the culmination of hundreds of experiments spanning decades. Early work showed measurable and reproducible changes in the optical properties of retinal explants and suspensions of Ph, and uncovered some of the biophysical and biochemical mechanisms underlying them. That work thus provided critical motivation for more recent work based on clinical imaging platforms, whose eventual goal is the improvement of ophthalmic care and streamlining the discovery of novel therapeutics. The first part of this review consists of a selective summary of the early work, and identifies four kinds of stimulus-evoked optical signals that have emerged from it: changes in light scattered from the membranous discs of the Ph’s outer segment (OS), changes in light scattered by the front and back boundaries of the OS, rearrangement of scattering material in and near the OS, and changes in the OS length. In the past decade, all four of these signals have continued to be investigated using imaging systems already used in the clinic or intended for clinical and translational use. The second part of this review discusses these imaging modalities, their potential to detect and quantify the signals of interest, and other factors influencing their translational promise. Particular attention is paid to phase-sensitive optical coherence tomography (OCT) with adaptive optics (AO), a method in which both the amplitude and the phase of light reflected from individual Ph is monitored as visible stimuli are delivered to them. The record of the light’s phase is decoded to reveal a reproducible pattern of deformation in the OS, while the amplitude reveals changes in scattering and structural rearrangements. The method has been demonstrated in a few labs and has been used to measure responses from both rods and cones. With the ability to detect responses to stimuli isomerizing less than 0.01% of photopigment, this technique may prove to be a quick, noninvasive, and objective way to measure subtle disease-related dysfunction at the cellular level, and thus to provide an entirely new and complementary biomarker for retinal disease and recovery.
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Affiliation(s)
- Ravi S Jonnal
- Department of Ophthalmology and Vision Science, University of California, Davis, CA, USA
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31
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Pandiyan VP, Jiang X, Kuchenbecker JA, Sabesan R. Reflective mirror-based line-scan adaptive optics OCT for imaging retinal structure and function. BIOMEDICAL OPTICS EXPRESS 2021; 12:5865-5880. [PMID: 34692221 PMCID: PMC8515964 DOI: 10.1364/boe.436337] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/16/2021] [Accepted: 08/20/2021] [Indexed: 05/06/2023]
Abstract
Line-scan OCT incorporated with adaptive optics (AO) offers high resolution, speed, and sensitivity for imaging retinal structure and function in vivo. Here, we introduce its implementation with reflective mirror-based afocal telescopes, optimized for imaging light-induced retinal activity (optoretinography) and weak retinal reflections at the cellular scale. A non-planar optical design was followed based on previous recommendations with key differences specific to a line-scan geometry. The three beam paths fundamental to an OCT system -illumination/sample, detection, and reference- were modeled in Zemax optical design software to yield theoretically diffraction-limited performance over a 2.2 deg. field-of-view and 1.5 D vergence range at the eye's pupil. The performance for imaging retinal structure was exemplified by cellular-scale visualization of retinal ganglion cells, macrophages, foveal cones, and rods in human observers. The performance for functional imaging was exemplified by resolving the light-evoked optical changes in foveal cone photoreceptors where the spatial resolution was sufficient for cone spectral classification at an eccentricity 0.3 deg. from the foveal center. This enabled the first in vivo demonstration of reduced S-cone (short-wavelength cone) density in the human foveola, thus far observed only in ex vivo histological preparations. Together, the feasibility for high resolution imaging of retinal structure and function demonstrated here holds significant potential for basic science and translational applications.
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Affiliation(s)
- Vimal Prabhu Pandiyan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
- Co-first authors with equal contribution
| | - Xiaoyun Jiang
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
- Co-first authors with equal contribution
| | - James A Kuchenbecker
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
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32
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Evaluation of focus and deep learning methods for automated image grading and factors influencing image quality in adaptive optics ophthalmoscopy. Sci Rep 2021; 11:16641. [PMID: 34404857 PMCID: PMC8371000 DOI: 10.1038/s41598-021-96068-2] [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: 10/13/2020] [Accepted: 07/19/2021] [Indexed: 11/08/2022] Open
Abstract
Adaptive optics flood illumination ophthalmoscopy (AO-FIO) is an established imaging tool in the investigation of retinal diseases. However, the clinical interpretation of AO-FIO images can be challenging due to varied image quality. Therefore, image quality assessment is essential before interpretation. An image assessment tool will also assist further work on improving the image quality, either during acquisition or post processing. In this paper, we describe, validate and compare two automated image quality assessment methods; the energy of Laplacian focus operator (LAPE; not commonly used but easily implemented) and convolutional neural network (CNN; effective but more complex approach). We also evaluate the effects of subject age, axial length, refractive error, fixation stability, disease status and retinal location on AO-FIO image quality. Based on analysis of 10,250 images of 50 × 50 μm size, at 41 retinal locations, from 50 subjects we demonstrate that CNN slightly outperforms LAPE in image quality assessment. CNN achieves accuracy of 89%, whereas LAPE metric achieves 73% and 80% (for a linear regression and random forest multiclass classifier methods, respectively) compared to ground truth. Furthermore, the retinal location, age and disease are factors that can influence the likelihood of poor image quality.
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33
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Cideciyan AV, Jacobson SG, Ho AC, Garafalo AV, Roman AJ, Sumaroka A, Krishnan AK, Swider M, Schwartz MR, Girach A. Durable vision improvement after a single treatment with antisense oligonucleotide sepofarsen: a case report. Nat Med 2021; 27:785-789. [PMID: 33795869 PMCID: PMC8127404 DOI: 10.1038/s41591-021-01297-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 03/01/2021] [Indexed: 12/21/2022]
Abstract
Leber congenital amaurosis due to CEP290 ciliopathy is being explored by treatment with the antisense oligonucleotide (AON) sepofarsen. One patient who was part of a larger cohort (ClinicalTrials.gov NCT03140969 ) was studied for 15 months after a single intravitreal sepofarsen injection. Concordant measures of visual function and retinal structure reached a substantial efficacy peak near 3 months after injection. At 15 months, there was sustained efficacy, even though there was evidence of reduction from peak response. Efficacy kinetics can be explained by the balance of AON-driven new CEP290 protein synthesis and a slow natural rate of CEP290 protein degradation in human foveal cone photoreceptors.
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Affiliation(s)
- Artur V Cideciyan
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Samuel G Jacobson
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Allen C Ho
- Wills Eye Hospital, Thomas Jefferson University, Philadelphia PA, USA
| | - Alexandra V Garafalo
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Alejandro J Roman
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Alexander Sumaroka
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Arun K Krishnan
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Malgorzata Swider
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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34
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Faure C, Cognard P, Robert MP. Late Contralateral Recurrence of Unilateral Acute Idiopathic Maculopathy: Adaptive Optics Findings. Ocul Immunol Inflamm 2021; 30:707-712. [PMID: 33617409 DOI: 10.1080/09273948.2020.1821897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
PURPOSE To report a case of late contralateral recurrence of unilateral acute idiopathic maculopathy (UAIM) and its sequelae by using adaptive optics. METHODS A 46-year-old woman positive for coxsackie virus presented with a typical UAIM, followed 3 years later by a recurrence in the fellow eye. At an early stage, spectral domain-OCT showed a localized loss of the inner segment/outer segment and cone outer segment tips lines, while flood-illumination adaptive optics displayed pigment clumpings and transient small hard exudates, associated with a persistent blurring of the cone mosaic. RESULTS These findings support the hypothesis of an outer retinal blood-barrier breakdown, inducing a disruption limited to the outer segment of the photoreceptors, followed by a progressive though incomplete normalization of the cone mosaic characterized by a persistent misalignment of outer segment tips. CONCLUSION This would explain the acute clinical presentation of UAIM, followed by a spontaneous, partial, recovery, with a relative scotoma remaining over time.
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Affiliation(s)
- Céline Faure
- Ramsay Générale de Santé, Hôpital Privé Saint Martin, Caen, France
| | - Pauline Cognard
- Ramsay Générale de Santé, Hôpital Privé Saint Martin, Caen, France
| | - Matthieu P Robert
- Service d'ophtalmologie, Hôpital Universitaire Necker-Enfants Malades, Paris, France.,Borelli Centre, UMR 9010, CNRS-SSA-ENS Paris Saclay-Paris University, Paris, France
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35
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Three-dimensional composition of the photoreceptor cone layers in healthy eyes using adaptive-optics optical coherence tomography (AO-OCT). PLoS One 2021; 16:e0245293. [PMID: 33412568 PMCID: PMC7790532 DOI: 10.1371/journal.pone.0245293] [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] [Received: 09/15/2020] [Accepted: 12/25/2020] [Indexed: 12/18/2022] Open
Abstract
Purpose To assess the signal composition of cone photoreceptors three-dimensionally in healthy retinas using adaptive optics optical coherence tomography (AO-OCT). Methods Study population. Twenty healthy eyes of ten subjects (age 23 to 67). Procedures. After routine ophthalmological assessments, eyes were examined using AO-OCT. Three-dimensional volumes were acquired at 2.5° and 6.5° foveal eccentricity in four main meridians (superior, nasal, inferior, temporal). Cone densities and signal compositions were investigated in four different planes: the cone inner segment outer segment junction (IS/OS), the cone outer segment combined with the IS/OS (ISOS+), the cone outer segment tips (COST) and full en-face plane (FEF) combining signals from all mentioned cone layers. Additionally, reliability of a simple semi-automated approach for assessment of cone density was tested. Main outcome measures. Cone density of IS/OS, IS/OS+, COST and FEF. Qualitative depiction and composition of each cone layer. Inter-rater agreement of cone density measurements. Results Mean overall cone density at all eccentricities was highest at the FEF plane (21.160/mm2), followed by COST (20.450/mm2), IS/OS+ (19.920/mm2) and IS/OS (19.530/mm2). The different meridians and eccentricities had a significant impact on cone density, with lower eccentricity resulting in higher cone densities (p≤.001), which were highest at the nasal, then temporal, then inferior and then superior meridian. Depiction of the cone mosaic differed between all 4 layers regarding signal size and packing density. Therefore, different cone layers showed evident but not complete signal overlap. Using the semi-automated technique for counting of cone signals achieved high inter-rater reliability (ICC > .99). Conclusions In healthy individuals qualitative and quantitative changes in cone signals are found not only in different eccentricities and meridians, but also within different photoreceptor layers. The variation between cone planes has to be considered when assessing the integrity of cone photoreceptors in healthy and diseased eyes using adaptive optics technology.
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Akyol E, Hagag AM, Sivaprasad S, Lotery AJ. Adaptive optics: principles and applications in ophthalmology. Eye (Lond) 2021; 35:244-264. [PMID: 33257798 PMCID: PMC7852593 DOI: 10.1038/s41433-020-01286-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 10/19/2020] [Accepted: 11/04/2020] [Indexed: 12/26/2022] Open
Abstract
This is a comprehensive review of the principles and applications of adaptive optics (AO) in ophthalmology. It has been combined with flood illumination ophthalmoscopy, scanning laser ophthalmoscopy, as well as optical coherence tomography to image photoreceptors, retinal pigment epithelium (RPE), retinal ganglion cells, lamina cribrosa and the retinal vasculature. In this review, we highlight the clinical studies that have utilised AO to understand disease mechanisms. However, there are some limitations to using AO in a clinical setting including the cost of running an AO imaging service, the time needed to scan patients, the lack of normative databases and the very small size of area imaged. However, it is undoubtedly an exceptional research tool that enables visualisation of the retina at a cellular level.
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Affiliation(s)
- Engin Akyol
- Faculty of Medicine, University of Southampton, Southampton, SO17 1BJ, UK
| | - Ahmed M Hagag
- NIHR Moorfields Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust, London, EC1V 2PD, UK
- UCL Institute of Ophthalmology, London, EC1V 9EL, UK
| | - Sobha Sivaprasad
- NIHR Moorfields Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust, London, EC1V 2PD, UK
- UCL Institute of Ophthalmology, London, EC1V 9EL, UK
| | - Andrew J Lotery
- Faculty of Medicine, University of Southampton, Southampton, SO17 1BJ, UK.
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Cooper RF, Brainard DH, Morgan JIW. Optoretinography of individual human cone photoreceptors. OPTICS EXPRESS 2020; 28:39326-39339. [PMID: 33379485 PMCID: PMC7771891 DOI: 10.1364/oe.409193] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 12/02/2020] [Accepted: 12/03/2020] [Indexed: 05/03/2023]
Abstract
Photoreceptors mediate the first step of vision, transducing light and passing signals to retinal neurons that ultimately send signals along the optic nerve to the brain. A functional deficiency in the photoreceptors, due to either congenital or acquired disease, can significantly affect an individual's sight and quality of life. Methods for quantifying the health and function of photoreceptors are essential for understanding both the progression of disease and the efficacy of treatment. Given that emerging treatments such as gene, stem cell, and small molecule therapy are designed to operate at the cellular scale, it is desirable to monitor function at the commensurate resolution of individual photoreceptors. Previously, non-invasive imaging methods for visualizing photoreceptor mosaic structure have been used to infer photoreceptor health, but these methods do not assess function directly. Conversely, most functional techniques, such as ERG and conventional microperimetry, measure function by aggregating the effects of signals from many photoreceptors. We have previously shown that stimulus-evoked intrinsic changes in intensity can be measured reliably in populations of cone photoreceptors in the intact human eye, a measurement we refer to more generally as the cone optoretinogram. Here we report that we can resolve the intensity optoretinogram at the level of individual cones. Moreover, we show that the individual cone optoretinogram exhibits two key signatures expected of a functional measure. First, responses in individual cones increase systematically as a function of stimulus irradiance. Second, we can use the amplitude of the functional response to middle wavelength (545 nm) light to separate the population of short-wavelength-sensitive (S) cones from the population of middle- and long-wavelength-sensitive (L and M) cones. Our results demonstrate the promise of optoretinography as a direct diagnostic measure of individual cone function in the living human eye.
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Affiliation(s)
- Robert F Cooper
- Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Scheie Eye Institute, Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Currently at the Joint Department of Biomedical Engineering, Marquette University and Medical College of Wisconsin and the Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, WI 53233, USA
| | - David H Brainard
- Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jessica I. W. Morgan
- Scheie Eye Institute, Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Center for Advanced Retinal and Ocular Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA
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Piedade WP, Titialii-Torres K, Morris AC, Famulski JK. Proteasome-Mediated Regulation of Cdhr1a by Siah1 Modulates Photoreceptor Development and Survival in Zebrafish. Front Cell Dev Biol 2020; 8:594290. [PMID: 33330480 PMCID: PMC7719784 DOI: 10.3389/fcell.2020.594290] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 10/22/2020] [Indexed: 01/05/2023] Open
Abstract
Congenital retinal dystrophies are a major cause of unpreventable and incurable blindness worldwide. Mutations in CDHR1, a retina specific cadherin, are associated with cone-rod dystrophy. The ubiquitin proteasome system (UPS) is responsible for mediating orderly and precise targeting of protein degradation to maintain biological homeostasis and coordinate proper development, including retinal development. Recently, our lab uncovered that the seven in absentia (Siah) family of E3 ubiquitin ligases play a role in optic fissure fusion and identified Cdhr1a as a potential target of Siah. Using two-color whole mount in situ hybridization and immunohistochemistry, we detected siah1 and cdhr1a co-expression as well as protein localization in the retinal outer nuclear layer (ONL), and more precisely in the connecting cilium of rods and cones between 3-5 days post fertilization (dpf). We confirmed that Siah1 targets Cdhr1a for proteasomal degradation by co-transfection and co-immunoprecipitation in cell culture. To analyze the functional importance of this interaction, we created two transgenic zebrafish lines that express siah1 or an inactive siah1 (siah1ΔRING) under the control of the heat shock promoter to modulate Siah activity during photoreceptor development. Overexpression of siah1, but not siah1ΔRING, resulted in a decrease in the number of rods and cones at 72 h post fertilization (hpf). The number of retinal ganglion cells, amacrine and bipolar cells was not affected by Siah1 overexpression, and there was no significant reduction of proliferating cells in the Siah1 overexpressing retina. We did, however, detect increased cell death, confirmed by an increase in the number of TUNEL + cells in the ONL, which was proteasome-dependent, as proteasome inhibition rescued the cell death phenotype. Furthermore, reduction in rods and cones resulting from increased Siah1 expression was rescued by injection of cdhr1a mRNA, and to an even greater extent by injection of a Siah1-insensitive cdhr1a variant mRNA. Lastly, CRISPR induced loss of Cdhr1a function phenocopied Siah1 overexpression resulting in a significant reduction of rods and cones. Taken together, our work provides the first evidence that Cdhr1a plays a role during early photoreceptor development and that Cdhr1a is regulated by Siah1 via the UPS.
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Affiliation(s)
| | | | | | - Jakub K. Famulski
- Department of Biology, University of Kentucky, Lexington, KY, United States
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Reumueller A, Wassermann L, Salas M, Schranz M, Told R, Kostolna K, Drexler W, Pircher M, Schmidt-Erfurth U, Pollreisz A. Three-dimensional assessment of para- and perifoveal photoreceptor densities and the impact of meridians and age in healthy eyes with adaptive-optics optical coherence tomography (AO-OCT). OPTICS EXPRESS 2020; 28:36723-36739. [PMID: 33379760 DOI: 10.1364/oe.409076] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 11/08/2020] [Indexed: 06/12/2023]
Abstract
An adaptive optics optical coherence tomography (AO-OCT) system is used to assess sixty healthy eyes of thirty subjects (age 22 to 75) to evaluate how the outer retinal layers, foveal eccentricity and age effect the mean cone density. The cone mosaics of different retinal planes (the cone inner segment outer segment junction (IS/OS), the cone outer segment combined with the IS/OS (ISOS+), the cone outer segment tips (COST), and the full en-face plane (FEF)) at four main meridians (superior, nasal, inferior, temporal) and para- and perifoveal eccentricities (ecc 2.5° and 6.5°) were analyzed quantitatively. The mean overall cone density was 19,892/mm2 at ecc 2.5° and 13,323/mm2 at ecc 6.5°. A significant impact on cone density was found for eccentricity (up to 6,700/mm2 between ecc 2.5° and 6.5°), meridian (up to 3,700/mm2 between nasal and superior meridian) and layer (up to 1,400/mm2 between FEF and IS/OS). Age showed only a weak negative effect. These factors as well as inter-individual variability have to be taken into account when comparing cone density measurements between healthy and pathologically changed eyes, as their combined effect on density can easily exceed several thousand cones per mm2 even in parafoveal regions.
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Wynne N, Carroll J, Duncan JL. Promises and pitfalls of evaluating photoreceptor-based retinal disease with adaptive optics scanning light ophthalmoscopy (AOSLO). Prog Retin Eye Res 2020; 83:100920. [PMID: 33161127 DOI: 10.1016/j.preteyeres.2020.100920] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/28/2020] [Accepted: 10/31/2020] [Indexed: 12/15/2022]
Abstract
Adaptive optics scanning light ophthalmoscopy (AOSLO) allows visualization of the living human retina with exquisite single-cell resolution. This technology has improved our understanding of normal retinal structure and revealed pathophysiological details of a number of retinal diseases. Despite the remarkable capabilities of AOSLO, it has not seen the widespread commercial adoption and mainstream clinical success of other modalities developed in a similar time frame. Nevertheless, continued advancements in AOSLO hardware and software have expanded use to a broader range of patients. Current devices enable imaging of a number of different retinal cell types, with recent improvements in stimulus and detection schemes enabling monitoring of retinal function, microscopic structural changes, and even subcellular activity. This has positioned AOSLO for use in clinical trials, primarily as exploratory outcome measures or biomarkers that can be used to monitor disease progression or therapeutic response. AOSLO metrics could facilitate patient selection for such trials, to refine inclusion criteria or to guide the choice of therapy, depending on the presence, absence, or functional viability of specific cell types. Here we explore the potential of AOSLO retinal imaging by reviewing clinical applications as well as some of the pitfalls and barriers to more widespread clinical adoption.
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Affiliation(s)
- Niamh Wynne
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Joseph Carroll
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jacque L Duncan
- Department of Ophthalmology, University of California, San Francisco, CA, USA.
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Miller DT, Kurokawa K. Cellular-Scale Imaging of Transparent Retinal Structures and Processes Using Adaptive Optics Optical Coherence Tomography. Annu Rev Vis Sci 2020; 6:115-148. [PMID: 32609578 PMCID: PMC7864592 DOI: 10.1146/annurev-vision-030320-041255] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
High-resolution retinal imaging is revolutionizing how scientists and clinicians study the retina on the cellular scale. Its exquisite sensitivity enables time-lapse optical biopsies that capture minute changes in the structure and physiological processes of cells in the living eye. This information is increasingly used to detect disease onset and monitor disease progression during early stages, raising the possibility of personalized eye care. Powerful high-resolution imaging tools have been in development for more than two decades; one that has garnered considerable interest in recent years is optical coherence tomography enhanced with adaptive optics. State-of-the-art adaptive optics optical coherence tomography (AO-OCT) makes it possible to visualize even highly transparent cells and measure some of their internal processes at all depths within the retina, permitting reconstruction of a 3D view of the living microscopic retina. In this review, we report current AO-OCT performance and its success in visualizing and quantifying these once-invisible cells in human eyes.
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Affiliation(s)
- Donald T Miller
- School of Optometry, Indiana University, Bloomington, Indiana 47405, USA; ,
| | - Kazuhiro Kurokawa
- School of Optometry, Indiana University, Bloomington, Indiana 47405, USA; ,
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Abstract
Rod photoreceptors are composed of a soma and an inner segment (IS) connected to an outer segment (OS) by a thin cilium. OSs are composed of a stack of ∼800 lipid discs surrounded by the plasma membrane where phototransduction takes place. Intracellular calcium plays a major role in phototransduction and is more concentrated in the discs, where it can be incorporated and released. To study calcium dynamics in rods, we used the fluorescent calcium dye CaSiR-1 AM working in the near-infrared (NIR) (excitation at 650 and emission at 664 nm), an advantage over previously used dyes. In this way, we investigated calcium dynamics with an unprecedented accuracy and most importantly in semidark-adapted conditions. We observed light-induced drops in [Ca2+]i with kinetics similar to that of photoresponses recorded electrophysiologically. We show three properties of the rods. First, intracellular calcium and key proteins have concentrations that vary from the OS base to tip. At the OS base, [Ca2+]i is ∼80 nM and increases up to ∼200 nM at the OS tip. Second, there are spontaneous calcium flares in healthy and functional rod OSs; these flares are highly localized and are more pronounced at the OS tip. Third, a bright flash of light at 488 nm induces a drop in [Ca2+]i at the OS base but often a flare at the OS tip. Therefore, rod OSs are not homogenous structures but have a structural and functional gradient, which is a fundamental aspect of transduction in vertebrate photoreceptors.
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Shirazi MF, Brunner E, Laslandes M, Pollreisz A, Hitzenberger CK, Pircher M. Visualizing human photoreceptor and retinal pigment epithelium cell mosaics in a single volume scan over an extended field of view with adaptive optics optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2020; 11:4520-4535. [PMID: 32923061 PMCID: PMC7449740 DOI: 10.1364/boe.393906] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 07/13/2020] [Accepted: 07/17/2020] [Indexed: 05/18/2023]
Abstract
Using adaptive optics optical coherence tomography, human photoreceptors and retinal pigment epithelium (RPE) cells are typically visualized on a small field of view of ∼1° to 2°. In addition, volume averaging is required for visualizing the RPE cell mosaic. To increase the imaging area, we introduce a lens based spectral domain AO-OCT system that shows low aberrations within an extended imaging area of 4°×4° while maintaining a high (theoretical) transverse resolution (at >7 mm pupil diameter) in the order of 2 µm. A new concept for wavefront sensing is introduced that uses light mainly originating from the RPE layer and yields images of the RPE cell mosaic in a single volume acquisition. The capability of the instrument for in vivo imaging is demonstrated by visualizing various cell structures within the posterior retinal layers over an extended field of view.
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Affiliation(s)
- Muhammad Faizan Shirazi
- Center for Medical Physics and Biomedical
Engineering, Medical University of Vienna, Waehringer Guertel 18-20,
A-1090 Vienna, Austria
| | - Elisabeth Brunner
- Center for Medical Physics and Biomedical
Engineering, Medical University of Vienna, Waehringer Guertel 18-20,
A-1090 Vienna, Austria
| | - Marie Laslandes
- ALPAO 727 rue Aristide Bergès 38330
Montbonnot-Saint-Martin, France
| | - Andreas Pollreisz
- Department of Ophthalmology and Optometry,
Medical University of Vienna, Vienna, Waehringer Guertel 18-20, A-1090
Vienna, Austria
| | - Christoph K. Hitzenberger
- Center for Medical Physics and Biomedical
Engineering, Medical University of Vienna, Waehringer Guertel 18-20,
A-1090 Vienna, Austria
| | - Michael Pircher
- Center for Medical Physics and Biomedical
Engineering, Medical University of Vienna, Waehringer Guertel 18-20,
A-1090 Vienna, Austria
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Chen HY, Kelley RA, Li T, Swaroop A. Primary cilia biogenesis and associated retinal ciliopathies. Semin Cell Dev Biol 2020; 110:70-88. [PMID: 32747192 PMCID: PMC7855621 DOI: 10.1016/j.semcdb.2020.07.013] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/14/2020] [Accepted: 07/18/2020] [Indexed: 12/19/2022]
Abstract
The primary cilium is a ubiquitous microtubule-based organelle that senses external environment and modulates diverse signaling pathways in different cell types and tissues. The cilium originates from the mother centriole through a complex set of cellular events requiring hundreds of distinct components. Aberrant ciliogenesis or ciliary transport leads to a broad spectrum of clinical entities with overlapping yet highly variable phenotypes, collectively called ciliopathies, which include sensory defects and syndromic disorders with multi-organ pathologies. For efficient light detection, photoreceptors in the retina elaborate a modified cilium known as the outer segment, which is packed with membranous discs enriched for components of the phototransduction machinery. Retinopathy phenotype involves dysfunction and/or degeneration of the light sensing photoreceptors and is highly penetrant in ciliopathies. This review will discuss primary cilia biogenesis and ciliopathies, with a focus on the retina, and the role of CP110-CEP290-CC2D2A network. We will also explore how recent technologies can advance our understanding of cilia biology and discuss new paradigms for developing potential therapies of retinal ciliopathies.
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Affiliation(s)
- Holly Y Chen
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, MSC0610, 6 Center Drive, Bethesda, MD 20892, USA.
| | - Ryan A Kelley
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, MSC0610, 6 Center Drive, Bethesda, MD 20892, USA
| | - Tiansen Li
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, MSC0610, 6 Center Drive, Bethesda, MD 20892, USA
| | - Anand Swaroop
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, MSC0610, 6 Center Drive, Bethesda, MD 20892, USA.
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Reumueller A, Wassermann L, Salas M, Karantonis MG, Sacu S, Georgopoulos M, Drexler W, Pircher M, Pollreisz A, Schmidt-Erfurth U. Morphologic and Functional Assessment of Photoreceptors After Macula-Off Retinal Detachment With Adaptive-Optics OCT and Microperimetry. Am J Ophthalmol 2020; 214:72-85. [PMID: 31883465 DOI: 10.1016/j.ajo.2019.12.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 12/11/2019] [Accepted: 12/13/2019] [Indexed: 12/21/2022]
Abstract
PURPOSE Limited information is available on morphologic and functional regeneration of photoreceptors after retinal detachment (RD) surgery. This observational clinical study compared morphologic and functional changes of cones after vitrectomy for macula-off retinal detachment. DESIGN Prospective, fellow-eye comparative case series. METHODS StudyPopulation: Five eyes after vitrectomy with gas for macula-off retinal detachment (retinal detachment eyes, RDE) and 5 healthy fellow eyes (HFE) of 5 patients (mean age 59.8 years, macula-off duration 0.5 days to 5.5 days). ObservationProcedures: Eyes were examined with adaptive-optics optical coherence tomography (AO-OCT), spectral-domain OCT (SDOCT), and microperimetry (MP) at 6 (baseline, BL) and 56 weeks (follow-up, FUP) after 23 gauge pars plana vitrectomy and SF6 gas tamponade. Eight corresponding regions at foveal eccentricities of 2.5° (ecc 2.5°) and 6.5° (ecc 6.5°) were analyzed in every eye. AO-OCT en face images and SD-OCT B-scans were graded regarding irregularity and loss of photoreceptor signals ranging from none to severe changes. The number of detectable cones at height of the inner-outer segment junction (IS/OS) and cone outer segment tips (COST) was counted manually in AO-OCT images. MP with a custom grid was used to assess retinal sensitivity at these locations. MainOutcomeMeasures: Cone density, cone pattern regularity and signal attenuation, retinal sensitivity. RESULTS In comparison to HFE, RDE showed highly irregular cone patterns in AO-OCT and irregular outer retinal bands in SDOCT. Despite significant improvement of cone pattern regularity compared to BL (P < .001), 63% of AO images showed remaining cone pattern irregularity and 45.5% of SDOCT B-scans showed severe signal reduction at FUP. In HFE, mean cone density retrieved from IS/OS and COST remained around 20,000/mm2 (ecc 2.5°) and 16,000/mm2 (ecc 6.5°) at BL and FUP. Cone density of RDE was significantly reduced and ranged between 200/mm2 and 15,600/mm2 (P < .001) at BL. Despite improvement at FUP (P < .001), mean cone density at IS/OS and COST was still lower compared to HFE and ranged between 7790 and 9555 cones/mm2 (P < .001). Mean retinal sensitivity of all measured locations remained 18 dB in HFE and was significantly lower in RDE, with 14.30 dB at BL and 14.64 dB at FUP. Both SDOCT grading and microperimetry sensitivity showed strong correlation with AO-OCT grading and cone density (rho values > 0.750). CONCLUSIONS The combination of AO-OCT, SDOCT, and microperimetry is a powerful tool to capture cone regeneration after vitreoretinal surgery. Our study shows that cone morphology and function improve within 56 weeks after RD surgery but structural and functional impairment is still present.
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Affiliation(s)
- Adrian Reumueller
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Lorenz Wassermann
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Matthias Salas
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | | | - Stefan Sacu
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Michael Georgopoulos
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Wolfgang Drexler
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Michael Pircher
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Andreas Pollreisz
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria.
| | - Ursula Schmidt-Erfurth
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
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46
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Carter SP, Moran AL, Matallanas D, McManus GJ, Blacque OE, Kennedy BN. Genetic Deletion of Zebrafish Rab28 Causes Defective Outer Segment Shedding, but Not Retinal Degeneration. Front Cell Dev Biol 2020; 8:136. [PMID: 32258030 PMCID: PMC7092623 DOI: 10.3389/fcell.2020.00136] [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: 11/19/2019] [Accepted: 02/18/2020] [Indexed: 01/14/2023] Open
Abstract
The photoreceptor outer segment is the canonical example of a modified and highly specialized cilium, with an expanded membrane surface area in the form of disks or lamellae for efficient light detection. Many ciliary proteins are essential for normal photoreceptor function and cilium dysfunction often results in retinal degeneration leading to impaired vision. Herein, we investigate the function and localization of the ciliary G-protein RAB28 in zebrafish cone photoreceptors. CRISPR-Cas9 generated rab28 mutant zebrafish display significantly reduced shed outer segment material/phagosomes in the RPE at 1 month post fertilization (mpf), but otherwise normal visual function up to 21 dpf and retinal structure up to 12 mpf. Cone photoreceptor-specific transgenic reporter lines show Rab28 localizes almost exclusively to outer segments, independently of GTP/GDP nucleotide binding. Co-immunoprecipitation analysis demonstrates tagged Rab28 interacts with components of the phototransduction cascade, including opsins, phosphodiesterase 6C and guanylate cyclase 2D. Our data shed light on RAB28 function in cones and provide a model for RAB28-associated cone-rod dystrophy.
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Affiliation(s)
- Stephen P Carter
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland.,UCD Conway Institute, University College Dublin, Dublin, Ireland
| | - Ailís L Moran
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland.,UCD Conway Institute, University College Dublin, Dublin, Ireland
| | - David Matallanas
- Systems Biology Ireland, University College Dublin, Dublin, Ireland
| | - Gavin J McManus
- School of Biochemistry and Immunology, Microscopy Facility, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
| | - Oliver E Blacque
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland.,UCD Conway Institute, University College Dublin, Dublin, Ireland
| | - Breandán N Kennedy
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland.,UCD Conway Institute, University College Dublin, Dublin, Ireland
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47
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Zhang P, Shibata B, Peinado G, Zawadzki RJ, FitzGerald P, Pugh EN. Measurement of Diurnal Variation in Rod Outer Segment Length In Vivo in Mice With the OCT Optoretinogram. Invest Ophthalmol Vis Sci 2020; 61:9. [PMID: 32176260 PMCID: PMC7401691 DOI: 10.1167/iovs.61.3.9] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 11/25/2019] [Indexed: 12/14/2022] Open
Abstract
Purpose To investigate diurnal variation in the length of mouse rod outer segments in vivo. Methods The lengths of rod inner and outer segments (RIS, ROS) of dark-adapted albino mice maintained on a 12-hour dark:12-hour light cycle with light onset 7 AM were measured at prescribed times (6:30 AM, 11 AM, 3:30 PM) during the diurnal cycle with optical coherence tomography (OCT), taking advantage of increased visibility, after a brief bleaching exposure, of the bands corresponding to RIS/ROS boundaries and ROS tips (ROST). Results Deconvolution of OCT depth profiles resolved two backscatter bands located 7.4 ± 0.1 and 10.8 ± 0.2 µm (mean ± SEM) proximal to Bruch's membrane (BrM). These bands were identified with histology as arising from the apical surface of RPE and ROST, respectively. The average length of dark-adapted ROS at 6:30 AM was 17.7 ± 0.8 µm. By 11 AM, the average ROS length had decreased by 10% to 15.9 ± 0.7 µm. After 11 AM, the ROS length increased steadily at an average rate of 0.12 µm/h, returning to baseline length by 23.5 hours in the cycle. Conclusions The diurnal variation in ROS length measured in these experiments is consistent with prior histological investigations showing that rodent rod discs are phagocytosed by the RPE maximally over several hours around the time of normal light onset. The rate of recovery of ROS to baseline length before normal light onset is consistent with the hypothesis that disc membrane synthesis is fairly constant over the diurnal cycle.
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Affiliation(s)
- Pengfei Zhang
- UC Davis Eye-Pod, Department of Cell Biology and Human Anatomy, University of California Davis, Davis, California, United States
| | - Bradley Shibata
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California Davis, Davis, California, United States
| | - Gabriel Peinado
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California Davis, Davis, California, United States
| | - Robert J. Zawadzki
- UC Davis Eye-Pod, Department of Cell Biology and Human Anatomy, University of California Davis, Davis, California, United States
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, California, United States
| | - Paul FitzGerald
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California Davis, Davis, California, United States
| | - Edward N. Pugh
- UC Davis Eye-Pod, Department of Cell Biology and Human Anatomy, University of California Davis, Davis, California, United States
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Cuenca N, Ortuño-Lizarán I, Sánchez-Sáez X, Kutsyr O, Albertos-Arranz H, Fernández-Sánchez L, Martínez-Gil N, Noailles A, López-Garrido JA, López-Gálvez M, Lax P, Maneu V, Pinilla I. Interpretation of OCT and OCTA images from a histological approach: Clinical and experimental implications. Prog Retin Eye Res 2020; 77:100828. [PMID: 31911236 DOI: 10.1016/j.preteyeres.2019.100828] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 12/16/2019] [Accepted: 12/30/2019] [Indexed: 12/17/2022]
Abstract
Optical coherence tomography (OCT) and OCT angiography (OCTA) have been a technological breakthrough in the diagnosis, treatment, and follow-up of many retinal diseases, thanks to its resolution and its ability to inform of the retinal state in seconds, which gives relevant information about retinal degeneration. In this review, we present an immunohistochemical description of the human and mice retina and we correlate it with the OCT bands in health and pathological conditions. Here, we propose an interpretation of the four outer hyperreflective OCT bands with a correspondence to retinal histology: the first and innermost band as the external limiting membrane (ELM), the second band as the cone ellipsoid zone (EZ), the third band as the outer segment tips phagocytosed by the pigment epithelium (PhaZ), and the fourth band as the mitochondria in the basal portion of the RPE (RPEmitZ). The integrity of these bands would reflect the health of photoreceptors and retinal pigment epithelium. Moreover, we describe how the vascular plexuses vary in different regions of the healthy human and mice retina, using OCTA and immunohistochemistry. In humans, four, three, two or one plexuses can be observed depending on the distance from the fovea. Also, specific structures such as vascular loops in the intermediate capillary plexus, or spider-like structures of interconnected capillaries in the deep capillary plexus are found. In mice, three vascular plexuses occupy the whole retina, except in the most peripheral retina where only two plexuses are found. These morphological issues should be considered when assessing a pathology, as some retinal diseases are associated with structural changes in blood vessels. Therefore, the analysis of OCT bands and OCTA vascular plexuses may be complementary for the diagnosis and prognosis of retinal degenerative processes, useful to assess therapeutic approaches, and it is usually correlated to visual acuity.
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Affiliation(s)
- Nicolás Cuenca
- Department of Physiology, Genetics and Microbiology, University of Alicante, Spain; Institute Ramón Margalef, University of Alicante, Alicante, Spain.
| | | | - Xavier Sánchez-Sáez
- Department of Physiology, Genetics and Microbiology, University of Alicante, Spain
| | - Oksana Kutsyr
- Department of Physiology, Genetics and Microbiology, University of Alicante, Spain
| | | | | | - Natalia Martínez-Gil
- Department of Physiology, Genetics and Microbiology, University of Alicante, Spain
| | - Agustina Noailles
- Department of Physiology, Genetics and Microbiology, University of Alicante, Spain
| | | | | | - Pedro Lax
- Department of Physiology, Genetics and Microbiology, University of Alicante, Spain
| | - Victoria Maneu
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Spain
| | - Isabel Pinilla
- Department of Ophthalmology, Lozano Blesa, University Hospital, Zaragoza, Spain
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49
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Meadway A, Sincich LC. Light reflectivity and interference in cone photoreceptors. BIOMEDICAL OPTICS EXPRESS 2019; 10:6531-6554. [PMID: 31853415 PMCID: PMC6913404 DOI: 10.1364/boe.10.006531] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 10/31/2019] [Accepted: 11/03/2019] [Indexed: 05/04/2023]
Abstract
In several modes of retinal imaging, the primary means of visualizing cone photoreceptors is from reflected light. Understanding how such images are formed, particularly when adaptive optics techniques are used, will help to guide their interpretation. Toward this end, we used finite difference beam propagation to model reflections from cone photoreceptors. We investigated the formation of cone images in adaptive optics scanning laser ophthalmoscopy (AOSLO) and optical coherence tomography (AOOCT). Three cone models were tested, one made up of three segments of varying refractive index, the other two having additional boundaries at the inner/outer segment junction and outer segment tip. Images formed by the first model did not correspond to AOOCT observations in the literature, while the latter two did. The predicted distributions of reflected light intensity from the latter cone models were compared to the distribution from AOSLO images, both studied with light sources of varied coherence length. The cone model with the most reflections at the inner/outer segment junction best fit the data measured in vivo. These results show that variance in cone reflection can originate from light interfering from reflectors much more closely spaced than the outer segment length. We also show that subtracting images taken with different coherence length sources highlights these changes in interference. Differential coherence images of cones occasionally revealed an annular reflection profile, which modeling showed to be very sensitive to cone size and the gaps bracketing the outer segment, suggesting that such imaging may be useful for probing photoreceptor morphology.
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Affiliation(s)
- Alexander Meadway
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Lawrence C. Sincich
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Borrelli E, Costanzo E, Parravano M, Viggiano P, Varano M, Giorno P, Marchese A, Sacconi R, Mastropasqua L, Bandello F, Querques G. Impact of Bleaching on Photoreceptors in Different Intermediate AMD Phenotypes. Transl Vis Sci Technol 2019; 8:5. [PMID: 31737429 PMCID: PMC6855373 DOI: 10.1167/tvst.8.6.5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 09/10/2019] [Indexed: 01/07/2023] Open
Abstract
Purpose To investigate photoreceptors' structural changes after photobleaching exposure in intermediate age-related macular degeneration (iAMD) eyes with and without reticular pseudodrusen (RPD). Methods In this prospective, cross-sectional study, were enrolled iAMD patients and healthy controls. Patients and controls underwent repeated imaging with spectral-domain optical coherence tomography (SD-OCT), at baseline and at three intervals after bleaching, during the subsequent recovery in darkness. Structural changes in photoreceptors were investigated in the foveal region and in four perifoveal areas. Results Twenty eyes of 20 iAMD patients (12 with RPD and 8 without RPD) and 15 age-matched healthy controls were enrolled. At baseline, the photoreceptor outer segment (OS) volume was significantly reduced in iAMD eyes with RPD compared with controls, in the foveal and perifoveal regions. In healthy subjects, a precocious increase in OS volume was observed after bleaching in the foveal region, and a rapid recovery to baseline values was recorded. In the perifoveal regions, an increase in OS volume was observed 10 minutes after light onset. In contrast, in iAMD subjects with RPD an altered response to photobleaching, in the foveal and superior and inferior perifoveal regions, was recorded. Conclusions Our imaging evidences support the hypothesis that dark adaptation is more altered in eyes with RPD. The structural modifications may explain the functional increased damage of the retinal pigment epithelium and photoreceptors reported in eyes with RPD. Translational Relevance OCT imaging may be used to assess dark adaptation in AMD eyes.
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Affiliation(s)
- Enrico Borrelli
- Ophthalmology Department, San Raffaele University Hospital, Milan, Italy
| | | | | | - Pasquale Viggiano
- Ophthalmology Clinic, Department of Medicine and Science of Ageing, University G. D'Annunzio Chieti-Pescara, Chieti, Italy
| | | | | | | | - Riccardo Sacconi
- Ophthalmology Department, San Raffaele University Hospital, Milan, Italy
| | - Leonardo Mastropasqua
- Ophthalmology Clinic, Department of Medicine and Science of Ageing, University G. D'Annunzio Chieti-Pescara, Chieti, Italy
| | - Francesco Bandello
- Ophthalmology Department, San Raffaele University Hospital, Milan, Italy
| | - Giuseppe Querques
- Ophthalmology Department, San Raffaele University Hospital, Milan, Italy
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