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Pinto AM, Jain N, Gupta RR. Pentosan Polysulfate Maculopathy With 13 Years of Follow-up Imaging. JOURNAL OF VITREORETINAL DISEASES 2024; 8:325-333. [PMID: 38770071 PMCID: PMC11102730 DOI: 10.1177/24741264241228375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Purpose: To describe a case of pentosan polysulfate maculopathy progression with 13 years of follow-up imaging. Methods: A case was analyzed and a literature review performed. Results: A 65-year-old woman was referred to the retina service for a second opinion of a bilateral progressive pigmentary maculopathy. Her medical history was significant for interstitial cystitis that was actively treated with daily pentosan polysulfate since 2003. Multimodal imaging and fundus examination were consistent with pentosan polysulfate maculopathy. A review of records showed previous fundus imaging dating back 13 years that permitted longitudinal assessment of the disease course. Imaging findings were more prominent than the fundus examination findings. There was a 5-year period from the onset of parafoveal atrophy to foveal involvement. A pseudopodial pattern of disease expansion was seen on fundus autofluorescence. Conclusions: To our knowledge, this case represents the longest documented follow-up imaging of the progression of pentosan polysulfate maculopathy in the literature.
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Affiliation(s)
- Ashlyn M. Pinto
- Department of Ophthalmology & Visual Sciences, Dalhousie University, Halifax, NS, Canada
| | - Nieraj Jain
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA, USA
| | - R. Rishi Gupta
- Department of Ophthalmology & Visual Sciences, Dalhousie University, Halifax, NS, Canada
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Sharkova M, Aparicio G, Mouzaaber C, Zolessi FR, Hocking JC. Photoreceptor calyceal processes accompany the developing outer segment, adopting a stable length despite a dynamic core. J Cell Sci 2024; 137:jcs261721. [PMID: 38477343 PMCID: PMC11058337 DOI: 10.1242/jcs.261721] [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: 10/16/2023] [Accepted: 03/04/2024] [Indexed: 03/14/2024] Open
Abstract
Vertebrate photoreceptors detect light through a large cilium-based outer segment, which is filled with photopigment-laden membranous discs. Surrounding the base of the outer segment are microvilli-like calyceal processes (CPs). Although CP disruption has been associated with altered outer segment morphology and photoreceptor degeneration, the role of the CPs remains elusive. Here, we used zebrafish as a model to characterize CPs. We quantified CP parameters and report a strong disparity in outer segment coverage between photoreceptor subtypes. CP length is stable across light and dark conditions, yet heat-shock inducible expression of tagged actin revealed rapid turnover of the CP actin core. Detailed imaging of the embryonic retina uncovered substantial remodeling of the developing photoreceptor apical surface, including a transition from dynamic tangential processes to vertically oriented CPs immediately prior to outer segment formation. Remarkably, we also found a direct connection between apical extensions of the Müller glia and retinal pigment epithelium, arranged as bundles around the ultraviolet sensitive cones. In summary, our data characterize the structure, development and surrounding environment of photoreceptor microvilli in the zebrafish retina.
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Affiliation(s)
- Maria Sharkova
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Gonzalo Aparicio
- Sección Biología Celular, Facultad de Ciencias, Universidad de la República, 11400, Uruguay
- Institut Pasteur Montevideo, Uruguay
| | - Constantin Mouzaaber
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Flavio R. Zolessi
- Sección Biología Celular, Facultad de Ciencias, Universidad de la República, 11400, Uruguay
- Institut Pasteur Montevideo, Uruguay
| | - Jennifer C. Hocking
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
- Division of Anatomy, Department of Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
- Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
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Williams BN, Draper A, Lang PF, Lewis TR, Smith AL, Mayerl SJ, Rougié M, Simon JM, Arshavsky VY, Greenwald SH, Gamm DM, Pinilla I, Philpot BD. Heterogeneity in the progression of retinal pathologies in mice harboring patient mimicking Impg2 mutations. Hum Mol Genet 2024; 33:448-464. [PMID: 37975905 PMCID: PMC10877459 DOI: 10.1093/hmg/ddad199] [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: 06/02/2023] [Revised: 11/08/2023] [Accepted: 11/09/2023] [Indexed: 11/19/2023] Open
Abstract
Biallelic mutations in interphotoreceptor matrix proteoglycan 2 (IMPG2) in humans cause retinitis pigmentosa (RP) with early macular involvement, albeit the disease progression varies widely due to genetic heterogeneity and IMPG2 mutation type. There are currently no treatments for IMPG2-RP. To aid preclinical studies toward eventual treatments, there is a need to better understand the progression of disease pathology in appropriate animal models. Toward this goal, we developed mouse models with patient mimicking homozygous frameshift (T807Ter) or missense (Y250C) Impg2 mutations, as well as mice with a homozygous frameshift mutation (Q244Ter) designed to completely prevent IMPG2 protein expression, and characterized the trajectory of their retinal pathologies across postnatal development until late adulthood. We found that the Impg2T807Ter/T807Ter and Impg2Q244Ter/Q244Ter mice exhibited early onset gliosis, impaired photoreceptor outer segment maintenance, appearance of subretinal deposits near the optic disc, disruption of the outer retina, and neurosensorial detachment, whereas the Impg2Y250C/Y250C mice exhibited minimal retinal pathology. These results demonstrate the importance of mutation type in disease progression in IMPG2-RP and provide a toolkit and preclinical data for advancing therapeutic approaches.
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Affiliation(s)
- Brittany N Williams
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, United States
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, United States
- Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, NC 27599, United States
| | - Adam Draper
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, United States
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, United States
| | - Patrick F Lang
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, United States
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, United States
| | - Tylor R Lewis
- Department of Ophthalmology, Duke University, Durham, NC 27705, United States
| | - Audrey L Smith
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, United States
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, United States
| | - Steven J Mayerl
- Department of Ophthalmology and Visual Sciences, McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, United States
| | - Marie Rougié
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, United States
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, United States
| | - Jeremy M Simon
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, United States
- Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, NC 27599, United States
| | - Vadim Y Arshavsky
- Department of Ophthalmology, Duke University, Durham, NC 27705, United States
| | | | - David M Gamm
- Department of Ophthalmology and Visual Sciences, McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, United States
| | - Isabel Pinilla
- Department of Ophthalmology, Lozano Blesa University Hospital, Zaragoza 50009, Spain
- Aragón Health Research Institute (IIS Aragón), Zaragoza 50009, Spain
- Department of Surgery, University of Zaragoza, Zaragoza 50009, Spain
| | - Benjamin D Philpot
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, United States
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, United States
- Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, NC 27599, United States
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Birtel J, Caswell R, De Silva SR, Herrmann P, Rehman S, Lotery AJ, Mahroo OA, Michaelides M, Webster AR, MacLaren RE, Charbel Issa P. IMPG2-Related Maculopathy. Am J Ophthalmol 2024; 258:32-42. [PMID: 37806544 DOI: 10.1016/j.ajo.2023.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 10/01/2023] [Accepted: 10/01/2023] [Indexed: 10/10/2023]
Abstract
PURPOSE To investigate the phenotype, variability, and penetrance of IMPG2-related maculopathy. DESIGN Retrospective observational case series. METHODS Clinical evaluation, multimodal retinal imaging, genetic testing, and molecular modeling. RESULTS A total of 25 individuals with a mono-allelic IMPG2 variant were included, 5 of whom were relatives of patients with IMPG2-associated retinitis pigmentosa. A distinct maculopathy was present in 17 individuals (median age, 52 years; range, 20-72 years), and included foveal elevation with or without subretinal vitelliform material or focal atrophy of the retinal pigment epithelium. Best-corrected visual acuity (BCVA) was ≥20/50 in the better eye (n = 15), and 5 patients were asymptomatic. Longitudinal observation (n = 8, up to 19 years) demonstrated stable maculopathy (n = 3), partial/complete resorption (n = 4) or increase (n = 1) of the subretinal material, with overall stable vision (n = 6). No manifest maculopathy was observed in 8 individuals (median age, 58 years; range, 43-83 years; BCVA ≥20/25), all were identified through segregation analysis. All 8 individuals were asymptomatic, with minimal foveal changes observed on optical coherence tomography in 3 cases. A total of 18 different variants were detected, 11 of them truncating. Molecular modeling of 5 missense variants [c.727G>C, c.1124C>A, c.2816T>A, c.3047T>C, and c.3193G>A] supported the hypothesis that these have a loss-of-function effect. CONCLUSIONS Mono-allelic IMPG2 variants may result in haploinsufficiency manifesting as a maculopathy with variable penetrance and expressivity. Family members of patients with IMPG2-related retinitis pigmentosa may present with vitelliform lesions. The maculopathy often remains limited to the fovea and is usually associated with moderate visual impairment.
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Affiliation(s)
- Johannes Birtel
- From the Oxford Eye Hospital (J.B., S.R.D.S., S.R., R.E.M., P.C.I.), Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom; Nuffield Laboratory of Ophthalmology (J.B., S.R.D.S., S.R., R.E.M., P.C.I.), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Department of Ophthalmology (J.B.), University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Department of Ophthalmology (J.B., P.H.), University of Bonn, Bonn, Germany
| | - Richard Caswell
- Exeter Genomics Laboratory (R.C.), Royal Devon University Healthcare NHS Foundation Trust, Exeter, United Kingdom
| | - Samantha R De Silva
- From the Oxford Eye Hospital (J.B., S.R.D.S., S.R., R.E.M., P.C.I.), Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom; Nuffield Laboratory of Ophthalmology (J.B., S.R.D.S., S.R., R.E.M., P.C.I.), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Moorfields Eye Hospital NHS Foundation Trust (S.R.D.S., O.A.M., M.M., A.R.W.), London, United Kingdom; UCL Institute of Ophthalmology (S.R.D.S., O.A.M., M.M., A.R.W.), University College London, London, United Kingdom
| | - Philipp Herrmann
- Department of Ophthalmology (J.B., P.H.), University of Bonn, Bonn, Germany
| | - Salwah Rehman
- From the Oxford Eye Hospital (J.B., S.R.D.S., S.R., R.E.M., P.C.I.), Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom; Nuffield Laboratory of Ophthalmology (J.B., S.R.D.S., S.R., R.E.M., P.C.I.), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Andrew J Lotery
- Clinical Neurosciences (A.J.L.), Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom; Southampton Eye Unit (A.J.L.), University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
| | - Omar A Mahroo
- Moorfields Eye Hospital NHS Foundation Trust (S.R.D.S., O.A.M., M.M., A.R.W.), London, United Kingdom; UCL Institute of Ophthalmology (S.R.D.S., O.A.M., M.M., A.R.W.), University College London, London, United Kingdom
| | - Michel Michaelides
- Moorfields Eye Hospital NHS Foundation Trust (S.R.D.S., O.A.M., M.M., A.R.W.), London, United Kingdom; UCL Institute of Ophthalmology (S.R.D.S., O.A.M., M.M., A.R.W.), University College London, London, United Kingdom
| | - Andrew R Webster
- Moorfields Eye Hospital NHS Foundation Trust (S.R.D.S., O.A.M., M.M., A.R.W.), London, United Kingdom; UCL Institute of Ophthalmology (S.R.D.S., O.A.M., M.M., A.R.W.), University College London, London, United Kingdom
| | - Robert E MacLaren
- From the Oxford Eye Hospital (J.B., S.R.D.S., S.R., R.E.M., P.C.I.), Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom; Nuffield Laboratory of Ophthalmology (J.B., S.R.D.S., S.R., R.E.M., P.C.I.), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Peter Charbel Issa
- From the Oxford Eye Hospital (J.B., S.R.D.S., S.R., R.E.M., P.C.I.), Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom; Nuffield Laboratory of Ophthalmology (J.B., S.R.D.S., S.R., R.E.M., P.C.I.), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.
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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: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [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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Liang Y, Sun X, Duan C, Tang S, Chen J. Application of patient-derived induced pluripotent stem cells and organoids in inherited retinal diseases. Stem Cell Res Ther 2023; 14:340. [PMID: 38012786 PMCID: PMC10683306 DOI: 10.1186/s13287-023-03564-5] [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: 08/29/2023] [Accepted: 11/06/2023] [Indexed: 11/29/2023] Open
Abstract
Inherited retinal diseases (IRDs) can induce severe sight-threatening retinal degeneration and impose a considerable economic burden on patients and society, making efforts to cure blindness imperative. Transgenic animals mimicking human genetic diseases have long been used as a primary research tool to decipher the underlying pathogenesis, but there are still some obvious limitations. As an alternative strategy, patient-derived induced pluripotent stem cells (iPSCs), particularly three-dimensional (3D) organoid technology, are considered a promising platform for modeling different forms of IRDs, including retinitis pigmentosa, Leber congenital amaurosis, X-linked recessive retinoschisis, Batten disease, achromatopsia, and best vitelliform macular dystrophy. Here, this paper focuses on the status of patient-derived iPSCs and organoids in IRDs in recent years concerning disease modeling and therapeutic exploration, along with potential challenges for translating laboratory research to clinical application. Finally, the importance of human iPSCs and organoids in combination with emerging technologies such as multi-omics integration analysis, 3D bioprinting, or microfluidic chip platform are highlighted. Patient-derived retinal organoids may be a preferred choice for more accurately uncovering the mechanisms of human retinal diseases and will contribute to clinical practice.
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Affiliation(s)
- Yuqin Liang
- Aier Eye Institute, Changsha, 410015, China
- Eye Center of Xiangya Hospital, Central South University, Changsha, 410008, China
| | - Xihao Sun
- Aier Eye Institute, Changsha, 410015, China
- Eye Center of Xiangya Hospital, Central South University, Changsha, 410008, China
| | - Chunwen Duan
- Aier Eye Institute, Changsha, 410015, China
- Changsha Aier Eye Hospital, Changsha, 410015, China
| | - Shibo Tang
- Aier Eye Institute, Changsha, 410015, China.
- Changsha Aier Eye Hospital, Changsha, 410015, China.
| | - Jiansu Chen
- Aier Eye Institute, Changsha, 410015, China.
- Changsha Aier Eye Hospital, Changsha, 410015, China.
- Key Laboratory for Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, 510632, China.
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Berlin A, Matney E, Jones SG, Clark ME, Swain TA, McGwin G, Martindale RM, Sloan KR, Owsley C, Curcio CA. Discernibility of the Interdigitation Zone (IZ), a Potential Optical Coherence Tomography (OCT) Biomarker for Visual Dysfunction in Aging. Curr Eye Res 2023; 48:1050-1056. [PMID: 37539829 PMCID: PMC10592305 DOI: 10.1080/02713683.2023.2240547] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Revised: 07/17/2023] [Accepted: 07/19/2023] [Indexed: 08/05/2023]
Abstract
PURPOSE Photoreceptor (PR) outer segments, retinal pigment epithelium apical processes, and inter-PR matrix contribute to the interdigitation zone (IZ) of optical coherence tomography (OCT). We hypothesize that this interface degrades over adulthood, in concert with a delay of rod mediated dark adaptation (RMDA). To explore this idea, we determined IZ discernibility and RMDA in younger and older adults. METHODS For this cross-sectional study, eyes of 20 young (20-30 years) and 40 older (≥60 years) participants with normal maculas according to the AREDS 9-step grading system underwent OCT imaging and RMDA testing at 5° superior to the fovea. Custom FIJI plugins enabled analysis for IZ discernibility at 9 eccentricities in 0.5 mm steps on one single horizontal B-scan through the fovea. Locations with discernible IZ met two criteria: visibility on B-scans and a distinct peak on a longitudinal reflectivity profile. The frequency of sites meeting both criteria was compared between both age groups and correlated with rod intercept time (RIT). RESULTS The median number of locations with discernible IZ was significantly higher (foveal, 4 vs. 0, p = 0.0099; extra-foveal 6 vs. 0, p < 0.001) in eyes of young (26 ± 3 years) compared to older (73 ± 5 years) participants. For the combined young and older sample, the higher frequency of discernible IZ was correlated with shorter RIT (faster dark adaptation) (rs = -0.56, p < 0.0001). This association was significant within young eyes (rs = -0.54; p = 0.0134) and not within older eyes (rs = -0.29, p = 0.706). CONCLUSIONS Results suggest that the interface between outer segments and apical processes degrades in normal aging, potentially contributing to delayed rod-mediated dark adaptation. More research is needed to verify an age-related association between IZ discernibility and rod-mediated dark adaptation. If confirmed in a large sample, IZ discernibility might prove to be a valuable biomarker and predictor for visual function in aging.
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Affiliation(s)
- Andreas Berlin
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham AL, USA
- University Hospital Würzburg, Würzburg, Germany
| | - Emily Matney
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham AL, USA
| | - Skyler G. Jones
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham AL, USA
| | - Mark E. Clark
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham AL, USA
| | - Thomas A Swain
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham AL, USA
| | - Gerald McGwin
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham AL, USA
- Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham AL USA
| | - Richard M. Martindale
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham AL, USA
| | - Kenneth R. Sloan
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham AL, USA
| | - Cynthia Owsley
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham AL, USA
| | - Christine A Curcio
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham AL, USA
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Chapelle AC, Rakic JM, Plant GT. The Occurrence of Intraretinal and Subretinal Fluid in Anterior Ischemic Optic Neuropathy: Pathogenesis, Prognosis, and Treatment. Ophthalmology 2023; 130:1191-1200. [PMID: 37479117 DOI: 10.1016/j.ophtha.2023.07.015] [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: 03/03/2023] [Revised: 07/04/2023] [Accepted: 07/13/2023] [Indexed: 07/23/2023] Open
Abstract
PURPOSE To describe the frequency and characteristics of intraretinal and subretinal fluid in nonarteritic anterior ischemic optic neuropathy (NAAION) and to assess the influence on the visual deficit and optic nerve fiber/ganglion cell loss. DESIGN A retrospective, single-center study. PARTICIPANTS Thirty-two patients with NAAION referred to our Neuro-ophthalmology Department between 2014 and 2021. METHODS The study was carried out at the University Hospital of Liège, Belgium. For participants in whom subretinal fluid was identified on standard OCT (Carl Zeiss Meditec) an additional macular OCT (Spectralis Heidelberg) had been performed. The pattern and the maximal height of the retinal fluid were determined manually, and thicknesses of retinal layers were obtained using the OCT protocol analysis. RESULTS The mean age of the cohort was 60 years (standard deviation, ±12.5; range, 22-88 years), and 65.6% were male. In the 21 eyes (46.7%) in which retinal fluid was observed, macular OCT findings were categorized according to fluid localization: 19 cases had parafoveal fluid (of whom 9 also had subfoveal fluid). One patient had subfoveal fluid alone, and 1 patient had peripapillary subretinal fluid alone. Specific patterns of optic disc (OD) swelling were associated with the occurrence and distribution of retinal edema. Visual acuity, visual field loss, and foveal thresholds were stable over the period of observation (P = 0.74, P = 0.42, and P = 0.36, respectively). No difference was found in visual function at 6 months between patients with retinal fluid treated (n = 10) or not treated (n = 11) with corticosteroids (visual acuity, P = 0.13; foveal threshold, P = 0.59; mean deviation, P = 0.66). CONCLUSIONS Subretinal fluid is found in a high proportion of cases of NAAION. Visual function remained largely stable from presentation in this cohort. Corticosteroid intake at presentation did not influence visual recovery or timing of the resorption of tissue edema. Our findings do not support treatment of NAAION with corticosteroids with or without evidence of subretinal fluid acutely. With regard to pathogenesis, we propose that the volume of transudate generated at the OD is the critical factor rather than dysfunction of retinal mechanisms subserving reabsorption. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
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Affiliation(s)
- Anne-Catherine Chapelle
- Department of Ophthalmology, Central University Hospital of Liège, University of Liège, Liège, Belgium.
| | - Jean-Marie Rakic
- Department of Ophthalmology, Central University Hospital of Liège, University of Liège, Liège, Belgium
| | - Gordon T Plant
- Department of Neurodegeneration and Rehabilitation, UCL Institute of Neurology, Faculty of Brain Sciences, University College London, London, United Kingdom
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Hong S, Weerasinghe-Mudiyanselage PDE, Kang S, Moon C, Shin T. Retinal transcriptome profiling identifies novel candidate genes associated with visual impairment in a mouse model of multiple sclerosis. Anim Cells Syst (Seoul) 2023; 27:219-233. [PMID: 37808551 PMCID: PMC10552570 DOI: 10.1080/19768354.2023.2264354] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 09/22/2023] [Indexed: 10/10/2023] Open
Abstract
Visual impairment is occasionally observed in multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). Although uveitis and optic neuritis have been reported in MS and EAE, the precise mechanisms underlying the pathogenesis of these visual impairments remain poorly understood. This study aims to identify differentially expressed genes (DEGs) in the retinas of mice with EAE to identify genes that may be implicated in EAE-induced visual impairment. Fourteen adult mice were injected with myelin oligodendrocyte glycoprotein35-55 to induce the EAE model. Transcriptomes of retinas with EAE were analyzed by RNA-sequencing. Gene expression analysis revealed 347 DEGs in the retinas of mice with EAE: 345 were upregulated, and 2 were downregulated (adjusted p-value < 0.05 and absolute log2 fold change > 1). Gene ontology (GO) analysis showed that the upregulated genes in the retinas of mice with EAE were primarily related to immune responses, responses to external biotic stimuli, defense responses, and leukocyte-mediated immunity in the GO biological process. The expression of six upregulated hub genes (c1qb, ctss, itgam, itgb2, syk, and tyrobp) from the STRING analysis and the two significantly downregulated DEGs (hapln1 and ndst4) were validated by reverse transcription-quantitative polymerase chain reaction. In addition, gene set enrichment analysis showed that the negatively enriched gene sets in EAE-affected retinas were associated with the neuronal system and phototransduction cascade. This study provides novel molecular evidence for visual impairments in EAE and indicates directions for further research to elucidate the mechanisms of these visual impairments in MS.
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Affiliation(s)
- Sungmoo Hong
- Department of Veterinary Anatomy, College of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju, Republic of Korea
| | - Poornima D. E. Weerasinghe-Mudiyanselage
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju, Republic of Korea
| | - Sohi Kang
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju, Republic of Korea
| | - Changjong Moon
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju, Republic of Korea
| | - Taekyun Shin
- Department of Veterinary Anatomy, College of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju, Republic of Korea
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10
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Castellini ME, Spagnolli G, Poggi L, Biasini E, Casarosa S, Messina A. Identification of the zebrafish homologues of IMPG2, a retinal proteoglycan. Cell Tissue Res 2023; 394:93-105. [PMID: 37470839 PMCID: PMC10558372 DOI: 10.1007/s00441-023-03808-z] [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: 03/06/2023] [Accepted: 07/05/2023] [Indexed: 07/21/2023]
Abstract
Photoreceptor outer segments are surrounded by a carbohydrate-rich matrix, the interphotoreceptor matrix, necessary for physiological retinal function. Few roles for molecules characterizing the interphotoreceptor matrix have been clearly defined. Recent studies have found the presence of nonsense mutations in the interphotoreceptor matrix proteoglycan 2 (IMPG2) gene in patients affected by retinal dystrophies. IMPG2 encodes for a proteoglycan synthesized by photoreceptors and secreted in the interphotoreceptor matrix. Little is known about the structure and function of this protein, we thus decided to characterize zebrafish impg2. In zebrafish there are two Impg2 proteins, Impg2a and Impg2b. We generated a phylogenetic tree based on IMPG2 protein sequence similarity among vertebrates, showing a significant similarity between humans and teleosts. The human and zebrafish proteins share conserved domains, as also shown by homology models. Expression analyses of impg2a and impg2b show a continued expression in the photoreceptor layer starting from developmental stages and continuing through adulthood. Between 1 and 6 months post-fertilization, there is a significant shift of Impg2 expression toward the outer segment region, suggesting an increase in secretion. This raises intriguing hypotheses about its possible role(s) during retinal maturation, laying the groundwork for the generation of most needed models for the study of IMPG2-related inherited retinal dystrophies.
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Affiliation(s)
- M E Castellini
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive, 9, 38123, Povo, TN, Italy
| | - G Spagnolli
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive, 9, 38123, Povo, TN, Italy
- Sibylla Biotech S.R.L, Piazzetta Chiavica 2 - 37121, Verona, VR, Italy
| | - L Poggi
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive, 9, 38123, Povo, TN, Italy
- Centre for Medical Sciences (CISMed), University of Trento, Via S. Maria Maddalena, 1, 38122, Trento, TN, Italy
| | - E Biasini
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive, 9, 38123, Povo, TN, Italy
- Centre for Medical Sciences (CISMed), University of Trento, Via S. Maria Maddalena, 1, 38122, Trento, TN, Italy
| | - S Casarosa
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive, 9, 38123, Povo, TN, Italy.
- Centre for Medical Sciences (CISMed), University of Trento, Via S. Maria Maddalena, 1, 38122, Trento, TN, Italy.
| | - A Messina
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive, 9, 38123, Povo, TN, Italy
- Centre for Mind/Brain Sciences (CIMeC), University of Trento, Piazza Manifattura 1, 38068, Rovereto, TN, Italy
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11
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Low SWY, Lim RR, Grant DG, Patterson S, Chaurasia SS. New Insights into RPE-Photoreceptor Complex Ultrastructure using Focused Ion Beam-Scanning Election Microscopy (FIB-SEM). RESEARCH SQUARE 2023:rs.3.rs-3200741. [PMID: 37609321 PMCID: PMC10441459 DOI: 10.21203/rs.3.rs-3200741/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Photoreceptors in the retina are specialized neuronal cells that perceive light and play a central role in the visual system. Damage to photoreceptors is a clinical feature often associated with various retinal degenerative disorders. The photoreceptor bed comprises a unique extracellular matrix (ECM) scaffold often described as the interphotoreceptor matrix (IPM) in the subretinal space, vital during retinal development and homeostasis. In this study, we used focused ion beam scanning electron microscopy (FIB-SEM) and transmission electron microscopy (TEM) to analyze the ultrastructural architecture of the retinal pigmented epithelium (RPE)-photoreceptor complex in mice. Additionally, we describe methods for retinal preparation in EM imaging. TEM images display ultrastructural retina layers, including Bruch's membrane and the interdigitation zone (IZ). The 3-dimensional reconstruction of the outer retina revealed individual photoreceptors, the connection between their inner and outer segment via the photoreceptor cilia, and photoreceptor interaction with the RPE ciliary processes. Our findings highlight the importance of FIB-SEM in deciphering the ultrastructural details of RPE-photoreceptor interactions in the IPM complex which are essential for the maintenance of retinal architecture.
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12
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Mousavi SF, Razmkabir M, Rostamzadeh J, Seyedabadi HR, Naboulsi R, Petersen JL, Lindgren G. Genetic diversity and signatures of selection in four indigenous horse breeds of Iran. Heredity (Edinb) 2023:10.1038/s41437-023-00624-7. [PMID: 37308718 PMCID: PMC10382556 DOI: 10.1038/s41437-023-00624-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 05/03/2023] [Accepted: 05/03/2023] [Indexed: 06/14/2023] Open
Abstract
Indigenous Iranian horse breeds were evolutionarily affected by natural and artificial selection in distinct phylogeographic clades, which shaped their genomes in several unique ways. The aims of this study were to evaluate the genetic diversity and genomewide selection signatures in four indigenous Iranian horse breeds. We evaluated 169 horses from Caspian (n = 21), Turkmen (n = 29), Kurdish (n = 67), and Persian Arabian (n = 52) populations, using genomewide genotyping data. The contemporary effective population sizes were 59, 98, 102, and 113 for Turkmen, Caspian, Persian Arabian, and Kurdish breeds, respectively. By analysis of the population genetic structure, we classified the north breeds (Caspian and Turkmen) and west/southwest breeds (Persian Arabian and Kurdish) into two phylogeographic clades reflecting their geographic origin. Using the de-correlated composite of multiple selection signal statistics based on pairwise comparisons, we detected a different number of significant SNPs under putative selection from 13 to 28 for the six pairwise comparisons (FDR < 0.05). The identified SNPs under putative selection coincided with genes previously associated with known QTLs for morphological, adaptation, and fitness traits. Our results showed HMGA2 and LLPH as strong candidate genes for height variation between Caspian horses with a small size and the other studied breeds with a medium size. Using the results of studies on human height retrieved from the GWAS catalog, we suggested 38 new putative candidate genes under selection. These results provide a genomewide map of selection signatures in the studied breeds, which represent valuable information for formulating genetic conservation and improved breeding strategies for the breeds.
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Affiliation(s)
- Seyedeh Fatemeh Mousavi
- Department of Animal Science, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Mohammad Razmkabir
- Department of Animal Science, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran.
| | - Jalal Rostamzadeh
- Department of Animal Science, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran.
| | - Hamid-Reza Seyedabadi
- Animal Science Research Institute of Iran, Agricultural Research Education and Extension Organization (AREEO), Karaj, Iran
| | - Rakan Naboulsi
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institute, Tomtebodavägen 18A, 17177, Stockholm, Sweden
| | | | - Gabriella Lindgren
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.
- Center for Animal Breeding and Genetics, Department of Biosystems, KU Leuven, 3001, Leuven, Belgium.
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13
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Sen S, Udaya P, Maheshwari JJ, Ramasamy K, Kannan NB, Dharmalingam K. Profiling of idiopathic macular hole vitreous proteome identifies the role of extracellular matrix remodelling, epithelial-mesenchymal transformation and unfolded protein-response pathways. Indian J Ophthalmol 2023; 71:2027-2040. [PMID: 37203077 PMCID: PMC10391365 DOI: 10.4103/ijo.ijo_2068_22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023] Open
Abstract
Purpose To analyze and describe the proteome of the vitreous humour in eyes with idiopathic macular holes. Methods We performed mass spectrometry (MS)-based label-free quantitative analysis of the vitreous proteome of idiopathic macular hole (IMH) and control donor vitreous. Comparative quantification was performed using SCAFFOLD software which calculated fold changes of differential expression. Bioinformatics analysis was performed using DAVID and STRING software. Results A total of 448 proteins were identified by LC-MS/MS in IMH and cadaveric eye vitreous samples, of which 199 proteins were common. IMH samples had 189 proteins that were unique and 60 proteins were present only in the control cadaveric vitreous. We found upregulation of several extracellular matrix (ECM) and cytoskeletal proteins, namely collagen alpha-1 (XVIII) chain, N-cadherin, EFEMP1/fibulin-3, basement membrane-specific heparan sulfate proteoglycan core protein, and target of Nesh-3. Several cytoskeleton proteins, namely tubulin, actin, and fibronectin levels, were significantly lower in IMH vitreous, probably reflecting increased ECM degradation. IMH vitreous also had a downregulation of unfolded protein response-mediated-mediated apoptosis proteins, possibly related to a state of increased cell survival and proliferation, along with a remodelling and aberrant production of ECM contents. Conclusion The pathogenesis of macular holes may involve ECM remodelling, epithelial-mesenchymal transformation, downregulation of apoptosis, protein folding defects, and complement pathway. The vitreo-retinal milieu in macular holes contain molecules related to both ECM degradation and inhibition of the same, thereby maintaining a homeostasis.
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Affiliation(s)
- Sagnik Sen
- Department of Retina and Vitreous, Aravind Eye Hospital; Department of Proteomics, Aravind Medical Research Foundation, Madurai, Tamil Nadu, India
| | - Prithviraj Udaya
- Department of Retina and Vitreous, Aravind Eye Hospital; Department of Proteomics, Aravind Medical Research Foundation, Madurai, Tamil Nadu, India
| | - Jayapal J Maheshwari
- Department of Proteomics, Aravind Medical Research Foundation, Madurai, Tamil Nadu, India
| | - Kim Ramasamy
- Department of Retina and Vitreous, Aravind Eye Hospital, Madurai, Tamil Nadu, India
| | - Naresh B Kannan
- Department of Retina and Vitreous, Aravind Eye Hospital, Madurai, Tamil Nadu, India
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14
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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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15
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Sharkova M, Chow E, Erickson T, Hocking JC. The morphological and functional diversity of apical microvilli. J Anat 2023; 242:327-353. [PMID: 36281951 PMCID: PMC9919547 DOI: 10.1111/joa.13781] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 10/03/2022] [Accepted: 10/05/2022] [Indexed: 11/30/2022] Open
Abstract
Sensory neurons use specialized apical processes to perceive external stimuli and monitor internal body conditions. The apical apparatus can include cilia, microvilli, or both, and is adapted for the functions of the particular cell type. Photoreceptors detect light through a large, modified cilium (outer segment), that is supported by a surrounding ring of microvilli-like calyceal processes (CPs). Although first reported 150 years ago, CPs remain poorly understood. As a basis for future study, we therefore conducted a review of existing literature about sensory cell microvilli, which can act either as the primary sensory detector or as support for a cilia-based detector. While all microvilli are finger-like cellular protrusions with an actin core, the processes vary across cell types in size, number, arrangement, dynamics, and function. We summarize the current state of knowledge about CPs and the characteristics of the microvilli found on inner ear hair cells (stereocilia) and cerebral spinal fluid-contacting neurons, with comparisons to the brush border of the intestinal and renal epithelia. The structure, stability, and dynamics of the actin core are regulated by a complement of actin-binding proteins, which includes both common components and unique features when compared across cell types. Further, microvilli are often supported by lateral links, a glycocalyx, and a defined extracellular matrix, each adapted to the function and environment of the cell. Our comparison of microvillar features will inform further research into how CPs support photoreceptor function, and also provide a general basis for investigations into the structure and functions of apical microvilli found on sensory neurons.
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Affiliation(s)
- Maria Sharkova
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Erica Chow
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Timothy Erickson
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Jennifer C Hocking
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.,Division of Anatomy, Department of Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.,Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.,Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
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16
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Towards a New Biomarker for Diabetic Retinopathy: Exploring RBP3 Structure and Retinoids Binding for Functional Imaging of Eyes In Vivo. Int J Mol Sci 2023; 24:ijms24054408. [PMID: 36901838 PMCID: PMC10002987 DOI: 10.3390/ijms24054408] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 02/10/2023] [Accepted: 02/21/2023] [Indexed: 02/25/2023] Open
Abstract
Diabetic retinopathy (DR) is a severe disease with a growing number of afflicted patients, which places a heavy burden on society, both socially and financially. While there are treatments available, they are not always effective and are usually administered when the disease is already at a developed stage with visible clinical manifestation. However, homeostasis at a molecular level is disrupted before visible signs of the disease are evident. Thus, there has been a constant search for effective biomarkers that could signal the onset of DR. There is evidence that early detection and prompt disease control are effective in preventing or slowing DR progression. Here, we review some of the molecular changes that occur before clinical manifestations are observable. As a possible new biomarker, we focus on retinol binding protein 3 (RBP3). We argue that it displays unique features that make it a very good biomarker for non-invasive, early-stage DR detection. Linking chemistry to biological function and focusing on new developments in eye imaging and two-photon technology, we describe a new potential diagnostic tool that would allow rapid and effective quantification of RBP3 in the retina. Moreover, this tool would also be useful in the future to monitor therapeutic effectiveness if levels of RBP3 are elevated by DR treatments.
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17
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Xu R, Wang Y, Du J, Salido EM. Retinal Metabolic Profile on IMPG2 Deficiency Mice with Subretinal Lesions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1415:457-463. [PMID: 37440072 DOI: 10.1007/978-3-031-27681-1_67] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
The interphotoreceptor matrix (IPM) is the extracellular matrix between the photoreceptors and the retinal pigment epithelium (RPE). The IPM has two proteoglycans: the IPM proteoglycans 1 and 2 (IMPG1 and IMPG2, respectively). Patients with mutations on IMPG2 develop subretinal vitelliform lesions that affect vision. We previously created an IMPG2 knockout (KO) mice model that generates subretinal lesions similar to those found in humans. These subretinal lesions in IMPG2 KO mice retinas are, in part, composed of mislocalized IMPG1. In addition, IMPG2 KO mice show microscopic IMPG1 material accumulation between the RPE and the photoreceptor outer segments. In this work we discuss the possibility that material accumulation on IMPG2 KO mice retinas affects photoreceptor metabolism. To further investigate this idea, we used targeted metabolomics to profile retinal metabolome on IMPG2 KO mice. The metabolite set enrichment analysis showed reduced glutamate metabolism, urea cycle, and galactose metabolism suggesting affected energy metabolism in mice retinas of IMPG2 KO mice with subretinal lesion.
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Affiliation(s)
- Rong Xu
- Departments of Biochemistry and molecular medicine, and Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV, USA
| | - Yekai Wang
- Departments of Biochemistry and molecular medicine, and Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV, USA
| | - Jianhai Du
- Departments of Biochemistry and molecular medicine, and Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV, USA
| | - Ezequiel M Salido
- Departments of Biochemistry and molecular medicine, and Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV, USA.
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18
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Serjanov D, Hyde DR. Extracellular Matrix: The Unexplored Aspects of Retinal Pathologies and Regeneration. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1415:309-317. [PMID: 37440050 DOI: 10.1007/978-3-031-27681-1_45] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Nearly a billion people worldwide are affected by vision-impairing conditions, with retinal degenerative diseases being a major cause of blindness. Unfortunately, such diseases are often permanent and progressive, resulting in further degeneration and loss of sight, due to the human retina possessing little, if any, regenerative capacity. Despite numerous efforts and great progress being made to understand the molecular mechanisms of these diseases and possible therapies, the majority of investigations focused on cell-intrinsic factors. However, the microenvironment surrounding retinal cells throughout these processes also plays an important role, though our current understanding of its involvement remains limited. Here we present a brief overview of the current state of the field of extracellular matrix studies within the retina and its potential roles in retinal diseases and potential therapeutic approaches.
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Affiliation(s)
- Dmitri Serjanov
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - David R Hyde
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA.
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19
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Berber P, Bondarenko S, Michaelis L, Weber BHF. Transient Retention of Photoreceptor Outer Segments in Matrigel-Embedded Retinal Organoids. Int J Mol Sci 2022; 23:ijms232314893. [PMID: 36499228 PMCID: PMC9739155 DOI: 10.3390/ijms232314893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 11/14/2022] [Accepted: 11/24/2022] [Indexed: 11/30/2022] Open
Abstract
Retinal organoids (ROs) are three-dimensional retinal tissues, which are differentiated in vitro from induced pluripotent stem cells (iPSC), ultimately forming all main retinal cell types under defined culture conditions. ROs show several highly specialized retinal features, including the outgrowth of photoreceptor outer segments (OSs). In vivo, the photoreceptor OSs are enveloped and maintained by protrusions of retinal pigment epithelium (RPE) cells, the so-called apical microvilli, while ROs fail to recapitulate this critical interaction in culture development. Here, we define specific co-culture conditions aiming to compensate for the missing physical proximity of RPE and OSs in RO development. Accordingly, functional RPE cells and ROs were differentiated simultaneously from the same iPSC clone, the former resulting in byproduct RPE or bRPE cells. While some co-culture approaches indicated a temporary functional interaction between bRPE and RO photoreceptors, they did not improve the photoreceptor histoarchitecture. In contrast, embedding ROs in a basement membrane extract without bRPE cells showed a robust improvement in the rate of photoreceptor OS retention. RO embedding is a quick and easy method that greatly enhances the preservation of photoreceptor OSs, an important structure for modelling retinal diseases with the involvement of photoreceptors.
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Affiliation(s)
- Patricia Berber
- Institute of Human Genetics, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
| | - Sofiia Bondarenko
- Institute of Human Genetics, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
| | - Lisa Michaelis
- Institute of Human Genetics, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
| | - Bernhard Heinrich Friedrich Weber
- Institute of Human Genetics, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
- Institute of Clinical Human Genetics, University Hospital Regensburg, 93053 Regensburg, Germany
- Correspondence:
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20
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Mayerl SJ, Bajgai S, Ludwig AL, Jager LD, Williams BN, Bacig C, Stoddard C, Sinha D, Philpot BD, Gamm DM. Human retinal organoids harboring IMPG2 mutations exhibit a photoreceptor outer segment phenotype that models advanced retinitis pigmentosa. Stem Cell Reports 2022; 17:2409-2420. [PMID: 36206764 PMCID: PMC9669399 DOI: 10.1016/j.stemcr.2022.09.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 09/06/2022] [Accepted: 09/07/2022] [Indexed: 11/05/2022] Open
Abstract
Interphotoreceptor matrix proteoglycan 2 (IMPG2) mutations cause a severe form of early-onset retinitis pigmentosa (RP) with macular involvement. IMPG2 is expressed by photoreceptors and incorporated into the matrix that surrounds the inner and outer segments (OS) of rods and cones, but the mechanism of IMPG2-RP remains unclear. Loss of Impg2 function in mice produces a mild, late-onset photoreceptor phenotype without the characteristic OS loss that occurs in human patients. We generated retinal organoids (ROs) from patient-derived induced pluripotent stem (iPS) cells and gene-edited embryonic stem cells to model human IMPG2-RP in vitro. All ROs harboring IMPG2 mutations lacked an OS layer, in contrast to isogenic controls. Subsequent protein analyses revealed that this phenotype arises due to a loss of IMPG2 expression or its inability to undergo normal post-translational modifications. We hypothesized that loss of IMPG2 function destabilizes the interphotoreceptor matrix and renders the OS vulnerable to physical stressors, which is accentuated in the tissue culture environment. In support of this mechanism, transplantation of IMPG2 mutant ROs into the protected subretinal space of immunocompromised rodents restored OS production. Beyond providing a robust platform to study IMPG2-RP, this human RO model system may serve a broader role in honing strategies to treat advanced photoreceptor-based diseases.
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Affiliation(s)
- Steven J Mayerl
- Cellular and Molecular Pathology University of Wisconsin-Madison, Madison, WI, USA; McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, USA; Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Simona Bajgai
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Allison L Ludwig
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, USA; Waisman Center, University of Wisconsin-Madison, Madison, WI, USA; Comparative Biomedical Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Lindsey D Jager
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Brittany N Williams
- Department of Cell Biology & Physiology, University of North Carolina, Chapel Hill, NC, USA; Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, NC, USA; Neuroscience Center, University of North Carolina, Chapel Hill, NC, USA
| | - Cole Bacig
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Christopher Stoddard
- Department of Genetics and Genome Sciences, University of Connecticut School of Medicine, Farmington, CT, USA
| | - Divya Sinha
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, USA; Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Benjamin D Philpot
- Department of Cell Biology & Physiology, University of North Carolina, Chapel Hill, NC, USA; Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, NC, USA; Neuroscience Center, University of North Carolina, Chapel Hill, NC, USA
| | - David M Gamm
- Cellular and Molecular Pathology University of Wisconsin-Madison, Madison, WI, USA; McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, USA; Waisman Center, University of Wisconsin-Madison, Madison, WI, USA; Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA.
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21
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Mitchell B, Coulter C, Geldenhuys WJ, Rhodes S, Salido EM. Interphotoreceptor matrix proteoglycans IMPG1 and IMPG2 proteolyze in the SEA domain and reveal localization mutual dependency. Sci Rep 2022; 12:15535. [PMID: 36109576 PMCID: PMC9478142 DOI: 10.1038/s41598-022-19910-1] [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: 07/07/2022] [Accepted: 09/06/2022] [Indexed: 11/08/2022] Open
Abstract
The interphotoreceptor matrix (IPM) is a specialized extracellular mesh of molecules surrounding the inner and outer segments of photoreceptor neurons. Interphotoreceptor matrix proteoglycan 1 and 2 (IMPG1 and IMPG2) are major components of the IPM. Both proteoglycans possess SEA (sperm protein, enterokinase and agrin) domains, which may support proteolysis. Interestingly, mutations in the SEA domains of IMPG1 and IMPG2 are associated with vision disease in humans. However, if SEA domains in IMPG molecules undergo proteolysis, and how this contributes to vision pathology is unknown. Therefore, we investigated SEA-mediated proteolysis of IMPG1 and IMPG2 and its significance to IPM physiology. Immunoblot analysis confirmed proteolysis of IMPG1 and IMPG2 in the retinas of wildtype mice. Point mutations mimicking human mutations in the SEA domain of IMPG1 that are associated with vision disease inhibited proteolysis. These findings demonstrate that proteolysis is part of the maturation of IMPG1 and IMPG2, in which deficits are associated with vision diseases. Further, immunohistochemical assays showed that proteolysis of IMPG2 generated two subunits, a membrane-attached peptide and an extracellular peptide. Notably, the extracellular portion of IMPG2 trafficked from the IPM around the inner segment toward the outer segment IPM by an IMPG1-dependent mechanism. This result provides the first evidence of a trafficking system that shuttles IMPG1 and IMPG2 from the inner to outer IPM in a co-dependent manner. In addition, these results suggest an interaction between IMPG1-IMPG2 and propose that mutations affecting one IMPG could affect the localization of the normal IMPG partner, contributing to the disease mechanism of vision diseases associated with defective IMPG molecules.
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Affiliation(s)
- Benjamin Mitchell
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV, USA
| | - Chloe Coulter
- Undergraduate Program in Biochemistry, West Virginia University, Morgantown, WV, USA
| | - Werner J Geldenhuys
- Department of Neuroscience, School of Medicine, West Virginia University, Morgantown, WV, USA
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, WV, USA
| | - Scott Rhodes
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV, USA
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV, USA
| | - Ezequiel M Salido
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV, USA.
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV, USA.
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22
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SPACR Encoded by IMPG1 Is Essential for Photoreceptor Survival by Interplaying between the Interphotoreceptor Matrix and the Retinal Pigment Epithelium. Genes (Basel) 2022; 13:genes13091508. [PMID: 36140676 PMCID: PMC9498744 DOI: 10.3390/genes13091508] [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: 07/29/2022] [Revised: 08/18/2022] [Accepted: 08/21/2022] [Indexed: 11/20/2022] Open
Abstract
Several pathogenic variants have been reported in the IMPG1 gene associated with the inherited retinal disorders vitelliform macular dystrophy (VMD) and retinitis pigmentosa (RP). IMPG1 and its paralog IMPG2 encode for two proteoglycans, SPACR and SPACRCAN, respectively, which are the main components of the interphotoreceptor matrix (IPM), the extracellular matrix surrounding the photoreceptor cells. To determine the role of SPACR in the pathological mechanisms leading to RP and VMD, we generated a knockout mouse model lacking Impg1, the mouse ortholog. Impg1-deficient mice show abnormal accumulation of autofluorescent deposits visible by fundus imaging and spectral-domain optical coherence tomography (SD-OCT) and attenuated electroretinogram responses from 9 months of age. Furthermore, SD-OCT of Impg1−/− mice shows a degeneration of the photoreceptor layer, and transmission electron microscopy shows a disruption of the IPM and the retinal pigment epithelial cells. The decrease in the concentration of the chromophore 11-cis-retinal supports this loss of photoreceptors. In conclusion, our results demonstrate the essential role of SPACR in maintaining photoreceptors. Impg1−/− mice provide a novel model for mechanistic investigations and the development of therapies for VMD and RP caused by IMPG1 pathogenic variants.
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23
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Vázquez-Domínguez I, Li CHZ, Fadaie Z, Haer-Wigman L, Cremers FPM, Garanto A, Hoyng CB, Roosing S. Identification of a Complex Allele in IMPG2 as a Cause of Adult-Onset Vitelliform Macular Dystrophy. Invest Ophthalmol Vis Sci 2022; 63:27. [PMID: 35608844 PMCID: PMC9150824 DOI: 10.1167/iovs.63.5.27] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Purpose Inherited retinal diseases are a group of clinically and genetically heterogeneous disorders with approximately 270 genes involved. IMPG2 is associated with adult-onset vitelliform macular dystrophy. Here, we investigated two unrelated patients with vitelliform macular dystrophy to identify the underlying genetic cause. Methods Whole-exome sequencing identified a putative causal complex allele consisting of c.3023-15T>A and c.3023G>A (p.(Gly1008Asp)) in IMPG2 in both individuals. To assess its effect, in vitro splice assays in HEK293T and further characterization in patient-derived photoreceptor precursor cells (PPCs) were conducted. Results The results of the midigene splice assays in HEK293T showed that the complex allele causes a variety of splicing defects ranging from a small deletion to (multiple-)exon skipping. This finding was further validated using patient-derived PPCs that showed a significant increase of out-of-frame transcripts lacking one or multiple exons compared to control-derived PPCs. Overall, control PPCs consistently showed low levels of aberrantly spliced IMPG2 transcripts that were highly elevated in patient-derived PPCs. These differences were even more obvious upon inhibition of nonsense-mediated decay with cycloheximide. Conclusions We report a heterozygous complex allele in IMPG2 causative for adult-onset vitelliform macular dystrophy in two unrelated individuals with mild visual loss and bilateral vitelliform lesions. The predicted causal missense mutation c.3023G>A, located in the consensus splice acceptor site, enhances the splicing effect of the upstream variant c.3023-15T>A, leading to the generation of aberrant transcripts that decrease the full-length IMPG2 levels. These results suggest a haploinsufficiency mechanism of action and highlight the complementarity of using different models to functionally assesses splicing defects.
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Affiliation(s)
- Irene Vázquez-Domínguez
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Catherina H Z Li
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands.,Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Zeinab Fadaie
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Lonneke Haer-Wigman
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Alejandro Garanto
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands.,Department of Pediatrics, Amalia Children's Hospital and Radboud Institute of Molecular Life Sciences (RIMLS), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Carel B Hoyng
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands.,Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Susanne Roosing
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
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24
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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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25
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Proteomic Analysis of Retinal Tissue in an S100B Autoimmune Glaucoma Model. BIOLOGY 2021; 11:biology11010016. [PMID: 35053014 PMCID: PMC8773367 DOI: 10.3390/biology11010016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 12/15/2021] [Accepted: 12/20/2021] [Indexed: 12/13/2022]
Abstract
Glaucoma is a neurodegenerative disease that leads to damage of retinal ganglion cells and the optic nerve. Patients display altered antibody profiles and increased antibody titer, e.g., against S100B. To identify the meaning of these antibodies, animals were immunized with S100B. Retinal ganglion cell loss, optic nerve degeneration, and increased glial cell activity were noted. Here, we aimed to gain more insights into the pathophysiology from a proteomic point of view. Hence, rats were immunized with S100B, while controls received sodium chloride. After 7 and 14 days, retinae were analyzed through mass spectrometry and immunohistology. Using data-independent acquisition-based mass spectrometry, we identified more than 1700 proteins on a high confidence level for both study groups, respectively. Of these 1700, 43 proteins were significantly altered in retinae after 7 days and 67 proteins revealed significant alterations at 14 days. For example, α2-macroglobulin was found significantly increased not only by mass spectrometry analysis, but also with immunohistological staining in S100B retinae at 7 and 14 days. All in all, the identified proteins are often associated with the immune system, such as heat shock protein 60. Once more, these data underline the important role of immunological factors in glaucoma pathogenesis.
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26
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Ma X, Takahashi Y, Wu W, Chen J, Dehdarani M, Liang W, Shin YH, Benyajati S, Ma JX. Soluble very low-density lipoprotein receptor (sVLDLR) inhibits fibrosis in neovascular age-related macular degeneration. FASEB J 2021; 35:e22058. [PMID: 34820908 PMCID: PMC9131420 DOI: 10.1096/fj.202101334r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/29/2021] [Accepted: 11/08/2021] [Indexed: 01/17/2023]
Abstract
Subretinal fibrosis is a key pathological feature in neovascular age‐related macular degeneration (nAMD). Previously, we identified soluble very low‐density lipoprotein receptor (sVLDLR) as an endogenous Wnt signaling inhibitor. This study investigates whether sVLDLR plays an anti‐fibrogenic role in nAMD models, including Vldlr−/− mice and laser‐induced choroidal neovascularization (CNV). We found that fibrosis factors including P‐Smad2/3, α‐SMA, and CTGF were upregulated in the subretinal area of Vldlr−/− mice and the laser‐induced CNV model. The antibody blocking Wnt co‐receptor LRP6 significantly attenuated the overexpression of fibrotic factors in these two models. Moreover, there was a significant reduction of sVLDLR in the interphotoreceptor matrix (IPM) in the laser‐induced CNV model. A transgenic strain (sVLDLR‐Tg) with sVLDLR overexpression in the IPM was generated. Overexpression of sVLDLR ameliorated the profibrotic changes in the subretinal area of the laser‐induced CNV model. In addition, Wnt and TGF‐β signaling synergistically promoted fibrogenesis in human primary retinal pigment epithelium (RPE) cells. CRISPR/Cas9‐mediated LRP6 gene knockout (KO) attenuated this synergistic effect. The disruption of VLDLR expression promoted, while the overexpression of sVLDLR inhibited TGF‐β‐induced fibrosis. These findings suggest that overactivated Wnt signaling enhances the TGF‐β pathway in subretinal fibrosis. sVLDLR confers an antifibrotic effect, at least partially, through the inhibition of Wnt signaling and thus, has therapeutic potential for fibrosis.
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Affiliation(s)
- Xiang Ma
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Yusuke Takahashi
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Wenjing Wu
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Jianglei Chen
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Marcus Dehdarani
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Wentao Liang
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Young-Hwa Shin
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Siribhinya Benyajati
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Jian-Xing Ma
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
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27
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Scaffold-Free Retinal Pigment Epithelium Microtissues Exhibit Increased Release of PEDF. Int J Mol Sci 2021; 22:ijms222111317. [PMID: 34768747 PMCID: PMC8583603 DOI: 10.3390/ijms222111317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/14/2021] [Accepted: 10/16/2021] [Indexed: 12/26/2022] Open
Abstract
The retinal pigmented epithelium (RPE) plays a critical role in photoreceptor survival and function. RPE deficits are implicated in a wide range of diseases that result in vision loss, including age-related macular degeneration (AMD) and Stargardt disease, affecting millions worldwide. Subretinal delivery of RPE cells is considered a promising avenue for treatment, and encouraging results from animal trials have supported recent progression into the clinic. However, the limited survival and engraftment of transplanted RPE cells delivered as a suspension continues to be a major challenge. While RPE delivery as epithelial sheets exhibits improved outcomes, this comes at the price of increased complexity at both the production and transplant stages. In order to combine the benefits of both approaches, we have developed size-controlled, scaffold-free RPE microtissues (RPE-µTs) that are suitable for scalable production and delivery via injection. RPE-µTs retain key RPE molecular markers, and interestingly, in comparison to conventional monolayer cultures, they show significant increases in the transcription and secretion of pigment-epithelium-derived factor (PEDF), which is a key trophic factor known to enhance the survival and function of photoreceptors. Furthermore, these microtissues readily spread in vitro on a substrate analogous to Bruch’s membrane, suggesting that RPE-µTs may collapse into a sheet upon transplantation. We anticipate that this approach may provide an alternative cell delivery system to improve the survival and integration of RPE transplants, while also retaining the benefits of low complexity in production and delivery.
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28
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Ma X, Takahashi Y, Wu W, Liang W, Chen J, Chakraborty D, Li Y, Du Y, Benyajati S, Ma JX. ADAM17 mediates ectodomain shedding of the soluble VLDL receptor fragment in the retinal epithelium. J Biol Chem 2021; 297:101185. [PMID: 34509473 PMCID: PMC8487060 DOI: 10.1016/j.jbc.2021.101185] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 08/27/2021] [Accepted: 09/07/2021] [Indexed: 11/19/2022] Open
Abstract
Very low-density lipoprotein receptor (VLDLR) is a multifunctional transmembrane protein. Beyond the function of the full-length VLDLR in lipid transport, the soluble ectodomain of VLDLR (sVLDLR) confers anti-inflammatory and antiangiogenic roles in ocular tissues through inhibition of canonical Wnt signaling. However, it remains unknown how sVLDLR is shed into the extracellular space. In this study, we present the first evidence that a disintegrin and metalloprotease 17 (ADAM17) is responsible for sVLDLR shedding in human retinal pigment epithelium cells using pharmacological and genetic approaches. Among selected proteinase inhibitors, an ADAM17 inhibitor demonstrated the most potent inhibitory effect on sVLDLR shedding. siRNA-mediated knockdown or CRISPR/Cas9-mediated KO of ADAM17 diminished, whereas plasmid-mediated overexpression of ADAM17 promoted sVLDLR shedding. The amount of shed sVLDLR correlated with an inhibitory effect on the Wnt signaling pathway. Consistent with these in vitro findings, intravitreal injection of an ADAM17 inhibitor reduced sVLDLR levels in the extracellular matrix in the mouse retina. In addition, our results demonstrated that ADAM17 cleaved VLDLR only in cells coexpressing these proteins, suggesting that shedding occurs in a cis manner. Moreover, our study demonstrated that aberrant activation of Wnt signaling was associated with decreased sVLDLR levels, along with downregulation of ADAM17 in ocular tissues of an age-related macular degeneration model. Taken together, our observations reveal the mechanism underlying VLDLR cleavage and identify a potential therapeutic target for the treatment of disorders associated with dysregulation of Wnt signaling.
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Affiliation(s)
- Xiang Ma
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Yusuke Takahashi
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Wenjing Wu
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Wentao Liang
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Jianglei Chen
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Dibyendu Chakraborty
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Yangxiong Li
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Yanhong Du
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Siribhinya Benyajati
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Jian-Xing Ma
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA.
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29
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Photoreceptor cKO of OTX2 Enhances OTX2 Intercellular Transfer in the Retina and Causes Photophobia. eNeuro 2021; 8:ENEURO.0229-21.2021. [PMID: 34475267 PMCID: PMC8496205 DOI: 10.1523/eneuro.0229-21.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 07/26/2021] [Accepted: 08/03/2021] [Indexed: 11/21/2022] Open
Abstract
In the mature mouse retina, Otx2 is expressed in both retinal pigmented epithelium (RPE) and photoreceptor (PR) cells, and Otx2 knock-out (KO) in the RPE alone results in PR degeneration. To study the cell-autonomous function of OTX2 in PRs, we performed PR-specific Otx2 KO (cKO) in adults. As expected, the protein disappears completely from PR nuclei but is still observed in PR inner and outer segments while its level concomitantly decreases in the RPE, suggesting a transfer of OTX2 from RPE to PRs in response to Otx2 ablation in PRs. The ability of OTX2 to transfer from RPE to PRs was verified by viral expression of tagged-OTX2 in the RPE. Transferred OTX2 distributed across the PR cytoplasm, suggesting functions distinct from nuclear transcription regulation. PR-specific Otx2 cKO did not alter the structure of the retina but impaired the translocation of PR arrestin-1 on illumination changes, making mice photophobic. RNA-seq analyses following Otx2 KO revealed downregulation of genes involved in the cytoskeleton that might account for the arrestin-1 translocation defect, and of genes involved in extracellular matrix (ECM) and signaling factors that may participate in the enhanced transfer of OTX2. Interestingly, several RPE-specific OTX2 target genes involved in melanogenesis were downregulated, lending weight to a decrease of OTX2 levels in the RPE following PR-specific Otx2 cKO. Our study reveals a new role of endogenous OTX2 in PR light adaptation and demonstrates the existence of OTX2 transfer from RPE to PR cells, which is increased on PR-specific Otx2 ablation and might participate in PR neuroprotection.
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30
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Xu H, Qu C, Gan L, Sun K, Tan J, Liu X, Jiang Z, Tian W, Liu W, Zhang S, Yang Y, Jiang L, Zhu X, Zhang L. Deletion of the Impg2 gene causes the degeneration of rod and cone cells in mice. Hum Mol Genet 2021; 29:1624-1634. [PMID: 32242237 DOI: 10.1093/hmg/ddaa062] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 03/18/2020] [Accepted: 03/30/2020] [Indexed: 11/14/2022] Open
Abstract
Variants in interphotoreceptor matrix proteoglycans (IMPG2) have been reported in retinitis pigmentosa (RP) and vitelliform macular dystrophy (VMD) patients. However, the underlying molecular mechanisms remain elusive due to a lack of suitable disease models. We developed two independent Impg2 knockout (KO) mouse models using the CRISPR/Cas9 technique to assess the in vivo functions of Impg2 in the retina. Impg2 ablation in mice recapitulated the RP phenotypes of patients, including an attenuated electroretinogram (ERG) response and the progressive degeneration of photoreceptors. The histopathological examination of Impg2-KO mice revealed irregularly arranged rod cells and mislocalized rhodopsin protein in the inner segment at 6 months of age. In addition to the pathological changes in rod cells, cone cells were also affected in KO retinas. KO retinas exhibited progressive cone cell death and impaired cone cell elongation. Further immunoblotting analysis revealed increased levels of endoplasmic reticulum (ER) stress-related proteins, including C/EBP homologous protein (CHOP), immunoglobulin heavy-chain-binding protein (BIP) and protein disulfide isomerase (PDI), in Impg2-KO mouse retinas. Increased gliosis and apoptotic cell death were also observed in the KO retinas. As autophagy is closely associated with ER stress, we then checked whether autophagy was disturbed in Impg2-KO mouse retinas. The results showed that autophagy was impaired in KO retinas, as revealed by the increased accumulation of SQSTM1 and other proteins involved in autophagy. Our results demonstrate the essential roles of Impg2 in the retina, and this study provides novel models for mechanistic investigations and development of therapies for RP caused by IMPG2 mutations.
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Affiliation(s)
- Huijuan Xu
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, Sichuan, China.,Chengdu Institute of Biology, Sichuan Translational Medicine Research Hospital, Chinese Academy of Sciences, Chengdu 610072, Sichuan, China.,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu 610072, Sichuan China
| | - Chao Qu
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, Sichuan, China.,Department of Ophthalmology, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu 610072, Sichuan China
| | - Li Gan
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, Sichuan, China
| | - Kuanxiang Sun
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, Sichuan, China
| | - Junkai Tan
- Xiamen Eye Center, Xiamen University, Xiamen 361005, China
| | - Xuyang Liu
- Xiamen Eye Center, Xiamen University, Xiamen 361005, China
| | - Zhilin Jiang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, Sichuan, China.,Department of Ophthalmology, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu 610072, Sichuan China
| | - Wanli Tian
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, Sichuan, China
| | - Wenjing Liu
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, Sichuan, China
| | - Shanshan Zhang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, Sichuan, China
| | - Yeming Yang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, Sichuan, China
| | - Li Jiang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, Sichuan, China.,Department of Ophthalmology, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu 610072, Sichuan China
| | - Xianjun Zhu
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, Sichuan, China.,Chengdu Institute of Biology, Sichuan Translational Medicine Research Hospital, Chinese Academy of Sciences, Chengdu 610072, Sichuan, China.,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu 610072, Sichuan China.,Research Unit for Blindness Prevention of Chinese Academy of medical Sciences (2019RU026), Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, Chengdu 610072, Sichuan, China.,Department of Ophthalmology, First People's Hospital of Shangqiu, Shangqiu 476000, Henan, China
| | - Lin Zhang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, Sichuan, China.,Research Unit for Blindness Prevention of Chinese Academy of medical Sciences (2019RU026), Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, Chengdu 610072, Sichuan, China
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31
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Tonade D, Kern TS. Photoreceptor cells and RPE contribute to the development of diabetic retinopathy. Prog Retin Eye Res 2021; 83:100919. [PMID: 33188897 PMCID: PMC8113320 DOI: 10.1016/j.preteyeres.2020.100919] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 10/27/2020] [Accepted: 10/31/2020] [Indexed: 12/26/2022]
Abstract
Diabetic retinopathy (DR) is a leading cause of blindness. It has long been regarded as vascular disease, but work in the past years has shown abnormalities also in the neural retina. Unfortunately, research on the vascular and neural abnormalities have remained largely separate, instead of being integrated into a comprehensive view of DR that includes both the neural and vascular components. Recent evidence suggests that the most predominant neural cell in the retina (photoreceptors) and the adjacent retinal pigment epithelium (RPE) play an important role in the development of vascular lesions characteristic of DR. This review summarizes evidence that the outer retina is altered in diabetes, and that photoreceptors and RPE contribute to retinal vascular alterations in the early stages of the retinopathy. The possible molecular mechanisms by which cells of the outer retina might contribute to retinal vascular damage in diabetes also are discussed. Diabetes-induced alterations in the outer retina represent a novel therapeutic target to inhibit DR.
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Affiliation(s)
- Deoye Tonade
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
| | - Timothy S Kern
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA; Veterans Administration Medical Center Research Service, Cleveland, OH, USA; Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA, USA; Veterans Administration Medical Center Research Service, Long Beach, CA, USA.
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Berkowitz BA, Qian H. OCT imaging of rod mitochondrial respiration in vivo. Exp Biol Med (Maywood) 2021; 246:2151-2158. [PMID: 34024141 DOI: 10.1177/15353702211013799] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
There remains a need for high spatial resolution imaging indices of mitochondrial respiration in the outer retina that probe normal physiology and measure pathogenic and reversible conditions underlying loss of vision. Mitochondria are involved in a critical, but somewhat underappreciated, support system that maintains the health of the outer retina involving stimulus-evoked changes in subretinal space hydration. The subretinal space hydration light-dark response is important because it controls the distribution of vision-critical interphotoreceptor matrix components, including anti-oxidants, pro-survival factors, ions, and metabolites. The underlying signaling pathway controlling subretinal space water management has been worked out over the past 30 years and involves cGMP/mitochondria respiration/pH/RPE water efflux. This signaling pathway has also been shown to be modified by disease-generating conditions, such as hypoxia or oxidative stress. Here, we review recent advances in MRI and commercially available OCT technologies that can measure stimulus-evoked changes in subretinal space water content based on changes in the external limiting membrane-retinal pigment epithelium region. Each step within the above signaling pathway can also be interrogated with FDA-approved pharmaceuticals. A highlight of these studies is the demonstration of first-in-kind in vivo imaging of mitochondria respiration of any cell in the body. Future examinations of subretinal space hydration are expected to be useful for diagnosing threats to sight in aging and disease, and improving the success rate when translating treatments from bench-to-bedside.
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Affiliation(s)
- Bruce A Berkowitz
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Haohua Qian
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Pentosan polysulfate maculopathy. Surv Ophthalmol 2021; 67:83-96. [PMID: 34000253 DOI: 10.1016/j.survophthal.2021.05.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 04/26/2021] [Accepted: 05/03/2021] [Indexed: 11/21/2022]
Abstract
Pentosan polysulfate sodium (PPS), a semisynthetic sulfated polysaccharide, is the only FDA-approved oral therapy for interstitial cystitis. Recent studies have described a progressive, vision-threatening macular condition associated with long-term PPS use. We reviewed all publications concerning PPS maculopathy to consolidate known clinical features and to evaluate the strength of this association. Current literature supports a strong dose-dependent association between PPS exposure and a progressive maculopathy impacting the retinal pigment epithelium (RPE) and RPE-photoreceptor interface that may worsen even after drug cessation. Initial symptoms may include prolonged dark adaptation and difficulty reading with relative visual acuity preservation. Fundus examination often shows macular pigment clumps corresponding to lesions of focal RPE thickening. Fundus autofluorescence most clearly depicts the condition, with a distinctive pattern of hypo- and hyperautofluorescent spots in the posterior pole that sometimes extends to the retinal periphery. Many cases also show a characteristic peripapillary hypoautofluorescent halo. Near infrared reflectance may aid in early detection. RPE atrophy, cystoid macular edema, and macular neovascularization may also occur, potentially resulting in loss of central acuity. This newly described association implies significant public health risk. Ophthalmologists should screen PPS users with multimodal retinal imaging, and prescribers should minimize dose and duration of PPS use.
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George SM, Lu F, Rao M, Leach LL, Gross JM. The retinal pigment epithelium: Development, injury responses, and regenerative potential in mammalian and non-mammalian systems. Prog Retin Eye Res 2021; 85:100969. [PMID: 33901682 DOI: 10.1016/j.preteyeres.2021.100969] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 03/23/2021] [Accepted: 04/07/2021] [Indexed: 12/13/2022]
Abstract
Diseases that result in retinal pigment epithelium (RPE) degeneration, such as age-related macular degeneration (AMD), are among the leading causes of blindness worldwide. Atrophic (dry) AMD is the most prevalent form of AMD and there are currently no effective therapies to prevent RPE cell death or restore RPE cells lost from AMD. An intriguing approach to treat AMD and other RPE degenerative diseases is to develop therapies focused on stimulating endogenous RPE regeneration. For this to become feasible, a deeper understanding of the mechanisms underlying RPE development, injury responses and regenerative potential is needed. In mammals, RPE regeneration is extremely limited; small lesions can be repaired by the expansion of adjacent RPE cells, but large lesions cannot be repaired as remaining RPE cells are unable to functionally replace lost RPE tissue. In some injury paradigms, RPE cells proliferate but do not regenerate a morphologically normal monolayer, while in others, proliferation is pathogenic and results in further disruption to the retina. This is in contrast to non-mammalian vertebrates, which possess tremendous RPE regenerative potential. Here, we discuss what is known about RPE formation during development in mammalian and non-mammalian vertebrates, we detail the processes by which RPE cells respond to injury, and we describe examples of RPE-to-retina and RPE-to-RPE regeneration in non-mammalian vertebrates. Finally, we outline barriers to RPE-dependent regeneration in mammals that could potentially be overcome to stimulate a regenerative response from the RPE.
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Affiliation(s)
- Stephanie M George
- Department of Ophthalmology, Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA
| | - Fangfang Lu
- Department of Ophthalmology, Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA; Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, China
| | - Mishal Rao
- Department of Ophthalmology, Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA
| | - Lyndsay L Leach
- Department of Ophthalmology, Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA
| | - Jeffrey M Gross
- Department of Ophthalmology, Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA; Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA.
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van Dijk EHC, Boon CJF. Serous business: Delineating the broad spectrum of diseases with subretinal fluid in the macula. Prog Retin Eye Res 2021; 84:100955. [PMID: 33716160 DOI: 10.1016/j.preteyeres.2021.100955] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 02/14/2021] [Accepted: 02/19/2021] [Indexed: 02/08/2023]
Abstract
A wide range of ocular diseases can present with serous subretinal fluid in the macula and therefore clinically mimic central serous chorioretinopathy (CSC). In this manuscript, we categorise the diseases and conditions that are part of the differential diagnosis into 12 main pathogenic subgroups: neovascular diseases, vitelliform lesions, inflammatory diseases, ocular tumours, haematological malignancies, paraneoplastic syndromes, genetic diseases, ocular developmental anomalies, medication-related conditions and toxicity-related diseases, rhegmatogenous retinal detachment and tractional retinal detachment, retinal vascular diseases, and miscellaneous diseases. In addition, we describe 2 new clinical pictures associated with macular subretinal fluid accumulation, namely serous maculopathy with absence of retinal pigment epithelium (SMARPE) and serous maculopathy due to aspecific choroidopathy (SMACH). Differentiating between these various diseases and CSC can be challenging, and obtaining the correct diagnosis can have immediate therapeutic and prognostic consequences. Here, we describe the key differential diagnostic features of each disease within this clinical spectrum, including representative case examples. Moreover, we discuss the pathogenesis of each disease in order to facilitate the differentiation from typical CSC.
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Affiliation(s)
- Elon H C van Dijk
- Department of Ophthalmology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, the Netherlands
| | - Camiel J F Boon
- Department of Ophthalmology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, the Netherlands; Department of Ophthalmology, Amsterdam University Medical Centers, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, the Netherlands.
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Age-related increase of let-7 family microRNA in rat retina and vitreous. Exp Eye Res 2021; 204:108434. [PMID: 33412132 DOI: 10.1016/j.exer.2020.108434] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 12/01/2020] [Accepted: 12/28/2020] [Indexed: 11/21/2022]
Abstract
Vitreous alterations occur from early stages and continue through the normal aging, with gradual lamellae formation and the appearance of liquefied spaces, which eventually leads to complications, such as retinal tear, retinal detachment, and intravitreal hemorrhage. The aim of the present study was to investigate the expression of let-7 miRNA family in the vitreous and retina in newborn (1-3- day-old), young adult (2-month-old), and aging (12-month-old) rats, as well as their role as regulators of vitreous components. MicroRNAs are small, non-coding RNAs that post-transcriptionally regulate gene expression. Our results showed detection of all investigated let-7 isoforms (let-7a, let-7b, let-7c, let-7d, let-7e, let-7f and let-7i) in the retina and vitreous. Although most let-7 members were significantly upregulated in the vitreous during development, only let-7b, let-7c, and let-7e followed this same expression pattern in the retina. Let-7b and -7c increased in aging vitreous as well, and were expressed in vitro by Müller glial cells and their extracellular vesicles. Moreover, let-7 targeted hyaluronan synthase 2 (Has2) mRNA, a synthesizing enzyme of hyaluronan. These observations indicate that let-7 function is important during retina and vitreous development, and that isoforms of let-7 increased with aging, potentially modulating hyaluronan content.
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37
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Zeng S, Zhang T, Madigan MC, Fernando N, Aggio-Bruce R, Zhou F, Pierce M, Chen Y, Huang L, Natoli R, Gillies MC, Zhu L. Interphotoreceptor Retinoid-Binding Protein (IRBP) in Retinal Health and Disease. Front Cell Neurosci 2020; 14:577935. [PMID: 33328889 PMCID: PMC7710524 DOI: 10.3389/fncel.2020.577935] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 10/21/2020] [Indexed: 02/05/2023] Open
Abstract
Interphotoreceptor retinoid-binding protein (IRBP), also known as retinol binding protein 3 (RBP3), is a lipophilic glycoprotein specifically secreted by photoreceptors. Enriched in the interphotoreceptor matrix (IPM) and recycled by the retinal pigment epithelium (RPE), IRBP is essential for the vision of all vertebrates as it facilitates the transfer of retinoids in the visual cycle. It also helps to transport lipids between the RPE and photoreceptors. The thiol-dependent antioxidant activity of IRBP maintains the delicate redox balance in the normal retina. Thus, its dysfunction is suspected to play a role in many retinal diseases. We have reviewed here the latest research on IRBP in both retinal health and disease, including the function and regulation of IRBP under retinal stress in both animal models and the human retina. We have also explored the therapeutic potential of targeting IRBP in retinal diseases. Although some technical barriers remain, it is possible that manipulating the expression of IRBP in the retina will rescue or prevent photoreceptor degeneration in many retinal diseases.
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Affiliation(s)
- Shaoxue Zeng
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia.,Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Ting Zhang
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia
| | - Michele C Madigan
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia.,School of Optometry and Vision Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Nilisha Fernando
- The John Curtin School of Medical Research, The Australian National University, Acton, ACT, Australia
| | - Riemke Aggio-Bruce
- The John Curtin School of Medical Research, The Australian National University, Acton, ACT, Australia.,The Australian National University Medical School, The Australian National University, Acton, ACT, Australia
| | - Fanfan Zhou
- Sydney Pharmacy School, The University of Sydney, Sydney, NSW, Australia
| | - Matthew Pierce
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia
| | - Yingying Chen
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia.,Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Lianlin Huang
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia.,School of Optometry and Vision Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Riccardo Natoli
- The John Curtin School of Medical Research, The Australian National University, Acton, ACT, Australia.,The Australian National University Medical School, The Australian National University, Acton, ACT, Australia
| | - Mark C Gillies
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia
| | - Ling Zhu
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia
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Kwon W, Freeman SA. Phagocytosis by the Retinal Pigment Epithelium: Recognition, Resolution, Recycling. Front Immunol 2020; 11:604205. [PMID: 33281830 PMCID: PMC7691529 DOI: 10.3389/fimmu.2020.604205] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 10/20/2020] [Indexed: 12/13/2022] Open
Abstract
Tissue-resident phagocytes are responsible for the routine binding, engulfment, and resolution of their meals. Such populations of cells express appropriate surface receptors that are tailored to recognize the phagocytic targets of their niche and initiate the actin polymerization that drives internalization. Tissue-resident phagocytes also harbor enzymes and transporters along the endocytic pathway that orchestrate the resolution of ingested macromolecules from the phagolysosome. Solutes fluxed from the endocytic pathway and into the cytosol can then be reutilized by the phagocyte or exported for their use by neighboring cells. Such a fundamental metabolic coupling between resident phagocytes and the tissue in which they reside is well-emphasized in the case of retinal pigment epithelial (RPE) cells; specialized phagocytes that are responsible for the turnover of photoreceptor outer segments (POS). Photoreceptors are prone to photo-oxidative damage and their long-term health depends enormously on the disposal of aged portions of the outer segment. The phagocytosis of the POS by the RPE is the sole means of this turnover and clearance. RPE are themselves mitotically quiescent and therefore must resolve the ingested material to prevent their toxic accumulation in the lysosome that otherwise leads to retinal disorders. Here we describe the sequence of events underlying the healthy turnover of photoreceptors by the RPE with an emphasis on the signaling that ensures the phagocytosis of the distal POS and on the transport of solutes from the phagosome that supersedes its resolution. While other systems may utilize different receptors and transporters, the biophysical and metabolic manifestations of such events are expected to apply to all tissue-resident phagocytes that perform regular phagocytic programs.
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Affiliation(s)
- Whijin Kwon
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada
| | - Spencer A Freeman
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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39
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Abstract
Cone photoreceptors in the retina are exposed to intense daylight and have higher energy demands in darkness. Cones produce energy using a large cluster of mitochondria. Mitochondria are susceptible to oxidative damage, and healthy mitochondrial populations are maintained by regular turnover. Daily cycles of light exposure and energy consumption suggest that mitochondrial turnover is important for cone health. We investigated the three-dimensional (3D) ultrastructure and metabolic function of zebrafish cone mitochondria throughout the day. At night retinas undergo a mitochondrial biogenesis event, corresponding to an increase in the number of smaller, simpler mitochondria and increased metabolic activity in cones. In the daytime, endoplasmic reticula (ER) and autophagosomes associate more with mitochondria, and mitochondrial size distribution across the cluster changes. We also report dense material shared between cone mitochondria that is extruded from the cell at night, sometimes forming extracellular structures. Our findings reveal an elaborate set of daily changes to cone mitochondrial structure and function.
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40
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Toulis V, García-Monclús S, de la Peña-Ramírez C, Arenas-Galnares R, Abril JF, Todi SV, Khan N, Garanto A, Costa MDC, Marfany G. The Deubiquitinating Enzyme Ataxin-3 Regulates Ciliogenesis and Phagocytosis in the Retina. Cell Rep 2020; 33:108360. [PMID: 33176149 PMCID: PMC8738964 DOI: 10.1016/j.celrep.2020.108360] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 09/04/2020] [Accepted: 10/17/2020] [Indexed: 01/07/2023] Open
Abstract
Expansion of a CAG repeat in ATXN3 causes the dominant polyglutamine disease spinocerebellar ataxia type 3 (SCA3), yet the physiological role of ATXN3 remains unclear. Here, we focus on unveiling the function of Ataxin-3 (ATXN3) in the retina, a neurological organ amenable to morphological and physiological studies. Depletion of Atxn3 in zebrafish and mice causes morphological and functional retinal alterations and, more precisely, photoreceptor cilium and outer segment elongation, cone opsin mislocalization, and cone hyperexcitation. ATXN3 localizes at the basal body and axoneme of the cilium, supporting its role in regulating ciliary length. Abrogation of Atxn3 expression causes decreased levels of the regulatory protein KEAP1 in the retina and delayed phagosome maturation in the retinal pigment epithelium. We propose that ATXN3 regulates two relevant biological processes in the retina, namely, ciliogenesis and phagocytosis, by modulating microtubule polymerization and microtubule-dependent retrograde transport, thus positing ATXN3 as a causative or modifier gene in retinal/macular dystrophies. Toulis et al. show that depletion of Atxn3 causes retinal morphological and electrophysiological alterations, as well as diminished phagocytosis in vivo and in vitro. ATXN3 regulates retinal ciliogenesis and phagocytosis through the KEAP1-SQSTM1-HDAC6-acetylated tubulin pathway by modulating microtubule polymerization and microtubule-dependent retrograde transport.
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Affiliation(s)
- Vasileios Toulis
- Departament de Genètica, Microbiologia i Estadística, Avda. Diagonal 643, Universitat de Barcelona, Barcelona 08028, Spain; CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain; Department of Neurology, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Sílvia García-Monclús
- Departament de Genètica, Microbiologia i Estadística, Avda. Diagonal 643, Universitat de Barcelona, Barcelona 08028, Spain
| | - Carlos de la Peña-Ramírez
- Departament de Genètica, Microbiologia i Estadística, Avda. Diagonal 643, Universitat de Barcelona, Barcelona 08028, Spain
| | - Rodrigo Arenas-Galnares
- Departament de Genètica, Microbiologia i Estadística, Avda. Diagonal 643, Universitat de Barcelona, Barcelona 08028, Spain; Institute of Biomedicine (IBUB, IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
| | - Josep F Abril
- Departament de Genètica, Microbiologia i Estadística, Avda. Diagonal 643, Universitat de Barcelona, Barcelona 08028, Spain; Institute of Biomedicine (IBUB, IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA; Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Naheed Khan
- Department of Ophthalmology and Visual Sciences, W. K. Kellogg Eye Center, University of Michigan, Ann Arbor, MI, USA
| | - Alejandro Garanto
- Departament de Genètica, Microbiologia i Estadística, Avda. Diagonal 643, Universitat de Barcelona, Barcelona 08028, Spain; Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Maria do Carmo Costa
- Department of Neurology, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA.
| | - Gemma Marfany
- Departament de Genètica, Microbiologia i Estadística, Avda. Diagonal 643, Universitat de Barcelona, Barcelona 08028, Spain; CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain; Institute of Biomedicine (IBUB, IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain.
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41
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Han IC, Cheng JL, Burnight ER, Ralston CL, Fick JL, Thomsen GJ, Tovar EF, Russell SR, Sohn EH, Mullins RF, Stone EM, Tucker BA, Wiley LA. Retinal Tropism and Transduction of Adeno-Associated Virus Varies by Serotype and Route of Delivery (Intravitreal, Subretinal, or Suprachoroidal) in Rats. Hum Gene Ther 2020; 31:1288-1299. [PMID: 32948113 DOI: 10.1089/hum.2020.043] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Viral-mediated gene augmentation offers tremendous promise for the treatment of inherited retinal diseases. The development of effective gene therapy requires an understanding of the vector's tissue-specific behavior, which may vary depending on serotype, route of delivery, or target species. Using an ex vivo organotypic explant system, we previously demonstrated that retinal tropism and transduction of adeno-associated virus type 2 (AAV2) vary significantly depending on serotype in human eyes. However, the ex vivo system has limited ability to assess route of ocular delivery, and relatively little literature exists on tropic differences between serotypes and routes of delivery in vivo. In this study, we demonstrate that retinal tropism and transduction efficiency of five different AAV2 serotypes (AAV2/1, AAV2/2, AAV2/6, AAV2/8, and AAV2/9) expressing enhanced green fluorescent protein driven by a cytomegalovirus promoter vary greatly depending on serotype and route of delivery (intravitreal, subretinal, or suprachoroidal) in rats. With subretinal delivery, all serotypes successfully transduced the retinal pigmented epithelium and outer nuclear layer (ONL), with AAV2/1 displaying the highest transduction efficiency and AAV2/2 and AAV2/6 showing lower ONL transduction. There was minimal transduction of the inner retina through subretinal delivery for any serotype. Tropism by suprachoroidal delivery mirrored that of subretinal delivery for all AAV serotypes but resulted in a wider distribution and greater ONL transduction. With intravitreal delivery, retinal transduction was seen primarily in the inner retina (retinal nerve fiber, ganglion cell, and inner nuclear layers) for AAV2/1 and AAV2/6, with AAV2/6 showing the highest transduction. When compared with data from human explant models, there are substantial differences in tropism and transduction that are important to consider when using rats as preclinical models for the development of ocular gene therapies for humans.
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Affiliation(s)
- Ian C Han
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Justine L Cheng
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Erin R Burnight
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Christy L Ralston
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Jessica L Fick
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Gabriella J Thomsen
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Emilio F Tovar
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Stephen R Russell
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Elliott H Sohn
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Robert F Mullins
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Edwin M Stone
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Budd A Tucker
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Luke A Wiley
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
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42
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Singh RK, Nasonkin IO. Limitations and Promise of Retinal Tissue From Human Pluripotent Stem Cells for Developing Therapies of Blindness. Front Cell Neurosci 2020; 14:179. [PMID: 33132839 PMCID: PMC7513806 DOI: 10.3389/fncel.2020.00179] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 05/25/2020] [Indexed: 12/13/2022] Open
Abstract
The self-formation of retinal tissue from pluripotent stem cells generated a tremendous promise for developing new therapies of retinal degenerative diseases, which previously seemed unattainable. Together with use of induced pluripotent stem cells or/and CRISPR-based recombineering the retinal organoid technology provided an avenue for developing models of human retinal degenerative diseases "in a dish" for studying the pathology, delineating the mechanisms and also establishing a platform for large-scale drug screening. At the same time, retinal organoids, highly resembling developing human fetal retinal tissue, are viewed as source of multipotential retinal progenitors, young photoreceptors and just the whole retinal tissue, which may be transplanted into the subretinal space with a goal of replacing patient's degenerated retina with a new retinal "patch." Both approaches (transplantation and modeling/drug screening) were projected when Yoshiki Sasai demonstrated the feasibility of deriving mammalian retinal tissue from pluripotent stem cells, and generated a lot of excitement. With further work and testing of both approaches in vitro and in vivo, a major implicit limitation has become apparent pretty quickly: the absence of the uniform layer of Retinal Pigment Epithelium (RPE) cells, which is normally present in mammalian retina, surrounds photoreceptor layer and develops and matures first. The RPE layer polarize into apical and basal sides during development and establish microvilli on the apical side, interacting with photoreceptors, nurturing photoreceptor outer segments and participating in the visual cycle by recycling 11-trans retinal (bleached pigment) back to 11-cis retinal. Retinal organoids, however, either do not have RPE layer or carry patches of RPE mostly on one side, thus directly exposing most photoreceptors in the developing organoids to neural medium. Recreation of the critical retinal niche between the apical RPE and photoreceptors, where many retinal disease mechanisms originate, is so far unattainable, imposes clear limitations on both modeling/drug screening and transplantation approaches and is a focus of investigation in many labs. Here we dissect different retinal degenerative diseases and analyze how and where retinal organoid technology can contribute the most to developing therapies even with a current limitation and absence of long and functional outer segments, supported by RPE.
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Ghareeb AE, Lako M, Steel DH. Coculture techniques for modeling retinal development and disease, and enabling regenerative medicine. Stem Cells Transl Med 2020; 9:1531-1548. [PMID: 32767661 PMCID: PMC7695644 DOI: 10.1002/sctm.20-0201] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 06/22/2020] [Accepted: 07/05/2020] [Indexed: 12/14/2022] Open
Abstract
Stem cell‐derived retinal organoids offer the opportunity to cure retinal degeneration of wide‐ranging etiology either through the study of in vitro models or the generation of tissue for transplantation. However, despite much work in animals and several human pilot studies, satisfactory therapies have not been developed. Two major challenges for retinal regenerative medicine are (a) physical cell‐cell interactions, which are critical to graft function, are not formed and (b) the host environment does not provide suitable queues for development. Several strategies offer to improve the delivery, integration, maturation, and functionality of cell transplantation. These include minimally invasive delivery, biocompatible material vehicles, retinal cell sheets, and optogenetics. Optimizing several variables in animal models is practically difficult, limited by anatomical and disease pathology which is often different to humans, and faces regulatory and ethical challenges. High‐throughput methods are needed to experimentally optimize these variables. Retinal organoids will be important to the success of these models. In their current state, they do not incorporate a representative retinal pigment epithelium (RPE)‐photoreceptor interface nor vascular elements, which influence the neural retina phenotype directly and are known to be dysfunctional in common retinal diseases such as age‐related macular degeneration. Advanced coculture techniques, which emulate the RPE‐photoreceptor and RPE‐Bruch's‐choriocapillaris interactions, can incorporate disease‐specific, human retinal organoids and overcome these drawbacks. Herein, we review retinal coculture models of the neural retina, RPE, and choriocapillaris. We delineate the scientific need for such systems in the study of retinal organogenesis, disease modeling, and the optimization of regenerative cell therapies for retinal degeneration.
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Affiliation(s)
- Ali E Ghareeb
- Sunderland Eye Infirmary, South Tyneside and Sunderland NHS Foundation Trust, Sunderland, UK.,Biosciences Institute, Newcastle University, Newcastle-upon-Tyne, UK
| | - Majlinda Lako
- Biosciences Institute, Newcastle University, Newcastle-upon-Tyne, UK
| | - David H Steel
- Sunderland Eye Infirmary, South Tyneside and Sunderland NHS Foundation Trust, Sunderland, UK.,Biosciences Institute, Newcastle University, Newcastle-upon-Tyne, UK
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EMT and EndMT: Emerging Roles in Age-Related Macular Degeneration. Int J Mol Sci 2020; 21:ijms21124271. [PMID: 32560057 PMCID: PMC7349630 DOI: 10.3390/ijms21124271] [Citation(s) in RCA: 118] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/12/2020] [Accepted: 06/14/2020] [Indexed: 02/06/2023] Open
Abstract
Epithelial–mesenchymal transition (EMT) and endothelial–mesenchymal transition (EndMT) are physiological processes required for normal embryogenesis. However, these processes can be hijacked in pathological conditions to facilitate tissue fibrosis and cancer metastasis. In the eye, EMT and EndMT play key roles in the pathogenesis of subretinal fibrosis, the end-stage of age-related macular degeneration (AMD) that leads to profound and permanent vision loss. Predominant in subretinal fibrotic lesions are matrix-producing mesenchymal cells believed to originate from the retinal pigment epithelium (RPE) and/or choroidal endothelial cells (CECs) through EMT and EndMT, respectively. Recent evidence suggests that EMT of RPE may also be implicated during the early stages of AMD. Transforming growth factor-beta (TGFβ) is a key cytokine orchestrating both EMT and EndMT. Investigations in the molecular mechanisms underpinning EMT and EndMT in AMD have implicated a myriad of contributing factors including signaling pathways, extracellular matrix remodelling, oxidative stress, inflammation, autophagy, metabolism and mitochondrial dysfunction. Questions arise as to differences in the mesenchymal cells derived from these two processes and their distinct mechanistic contributions to the pathogenesis of AMD. Detailed discussion on the AMD microenvironment highlights the synergistic interactions between RPE and CECs that may augment the EMT and EndMT processes in vivo. Understanding the differential regulatory networks of EMT and EndMT and their contributions to both the dry and wet forms of AMD can aid the development of therapeutic strategies targeting both RPE and CECs to potentially reverse the aberrant cellular transdifferentiation processes, regenerate the retina and thus restore vision.
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Abstract
Patients with diabetes continue to suffer from impaired visual performance before the appearance of overt damage to the retinal microvasculature and later sight-threatening complications. This diabetic retinopathy (DR) has long been thought to start with endothelial cell oxidative stress. Yet newer data surprisingly finds that the avascular outer retina is the primary site of oxidative stress before microvascular histopathology in experimental DR. Importantly, correcting this early oxidative stress is sufficient to restore vision and mitigate the histopathology in diabetic models. However, translating these promising results into the clinic has been stymied by an absence of methods that can measure and optimize anti-oxidant treatment efficacy in vivo. Here, we review imaging approaches that address this problem. In particular, diabetes-induced oxidative stress impairs dark-light regulation of subretinal space hydration, which regulates the distribution of interphotoreceptor binding protein (IRBP). IRBP is a vision-critical, anti-oxidant, lipid transporter, and pro-survival factor. We show how optical coherence tomography can measure subretinal space oxidative stress thus setting the stage for personalizing anti-oxidant treatment and prevention of impactful declines and loss of vision in patients with diabetes.
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46
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Toms D, Al-Ani A, Sunba S, Tong QYV, Workentine M, Ungrin M. Automated Hypothesis Generation to Identify Signals Relevant in the Development of Mammalian Cell and Tissue Bioprocesses, With Validation in a Retinal Culture System. Front Bioeng Biotechnol 2020; 8:534. [PMID: 32582664 PMCID: PMC7287043 DOI: 10.3389/fbioe.2020.00534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 05/04/2020] [Indexed: 12/13/2022] Open
Abstract
We have developed an accessible software tool (receptoR) to predict potentially active signaling pathways in one or more cell type(s) of interest from publicly available transcriptome data. As proof-of-concept, we applied it to mouse photoreceptors, yielding the previously untested hypothesis that activin signaling pathways are active in these cells. Expression of the type 2 activin receptor (Acvr2a) was experimentally confirmed by both RT-qPCR and immunochemistry, and activation of this signaling pathway with recombinant activin A significantly enhanced the survival of magnetically sorted photoreceptors in culture. Taken together, we demonstrate that our approach can be easily used to mine publicly available transcriptome data and generate hypotheses around receptor expression that can be used to identify novel signaling pathways in specific cell types of interest. We anticipate that receptoR (available at https://www.ucalgary.ca/ungrinlab/receptoR) will enable more efficient use of limited research resources.
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Affiliation(s)
- Derek Toms
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
| | - Abdullah Al-Ani
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada.,Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada.,Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada.,Leaders in Medicine Program, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Saud Sunba
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Qing Yun Victor Tong
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Matthew Workentine
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Mark Ungrin
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada.,Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada.,Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
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47
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Zhang C, Miyagishima KJ, Dong L, Rising A, Nimmagadda M, Liang G, Sharma R, Dejene R, Wang Y, Abu-Asab M, Qian H, Li Y, Kopera M, Maminishkis A, Martinez J, Miller S. Regulation of phagolysosomal activity by miR-204 critically influences structure and function of retinal pigment epithelium/retina. Hum Mol Genet 2020; 28:3355-3368. [PMID: 31332443 DOI: 10.1093/hmg/ddz171] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 07/04/2019] [Accepted: 07/09/2019] [Indexed: 12/13/2022] Open
Abstract
MicroRNA-204 (miR-204) is expressed in pulmonary, renal, mammary and eye tissue, and its reduction can result in multiple diseases including cancer. We first generated miR-204-/- mice to study the impact of miR-204 loss on retinal and retinal pigment epithelium (RPE) structure and function. The RPE is fundamentally important for maintaining the health and integrity of the retinal photoreceptors. miR-204-/- eyes evidenced areas of hyper-autofluorescence and defective photoreceptor digestion, along with increased microglia migration to the RPE. Migratory Iba1+ microglial cells were localized to the RPE apical surface where they participated in the phagocytosis of photoreceptor outer segments (POSs) and contributed to a persistent build-up of rhodopsin. These structural, molecular and cellular outcomes were accompanied by decreased light-evoked electrical responses from the retina and RPE. In parallel experiments, we suppressed miR-204 expression in primary cultures of human RPE using anti-miR-204. In vitro suppression of miR-204 in human RPE similarly showed abnormal POS clearance and altered expression of autophagy-related proteins and Rab22a, a regulator of endosome maturation. Together, these in vitro and in vivo experiments suggest that the normally high levels of miR-204 in RPE can mitigate disease onset by preventing generation of oxidative stress and inflammation originating from intracellular accumulation of undigested photoreactive POS lipids. More generally, these results implicate RPE miR-204-mediated regulation of autophagy and endolysosomal interaction as a critical determinant of normal RPE/retina structure and function.
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Affiliation(s)
- Congxiao Zhang
- Ophthalmic Genetics and Visual Function Branch, Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, MD USA
| | - Kiyoharu J Miyagishima
- Ophthalmic Genetics and Visual Function Branch, Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, MD USA
| | - Lijin Dong
- Genetic Engineering Facility, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Aaron Rising
- Ophthalmic Genetics and Visual Function Branch, Unit on Ocular and Stem Cell Translational Research, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Malika Nimmagadda
- Ophthalmic Genetics and Visual Function Branch, Unit on Ocular and Stem Cell Translational Research, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Genqing Liang
- Ophthalmic Genetics and Visual Function Branch, Unit on Ocular and Stem Cell Translational Research, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Ruchi Sharma
- Ophthalmic Genetics and Visual Function Branch, Unit on Ocular and Stem Cell Translational Research, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Roba Dejene
- Ophthalmic Genetics and Visual Function Branch, Unit on Ocular and Stem Cell Translational Research, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Yuan Wang
- Ophthalmic Genetics and Visual Function Branch, Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, MD USA
| | - Mones Abu-Asab
- Section of Histopathology, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Haohua Qian
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Yichao Li
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Megan Kopera
- Genetic Engineering Facility, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Arvydas Maminishkis
- Ophthalmic Genetics and Visual Function Branch, Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, MD USA
| | - Jennifer Martinez
- Inflammation and Autoimmunity, National Institute of Environmental Sciences, National Institutes of Health, Bethesda, MD, USA
| | - Sheldon Miller
- Ophthalmic Genetics and Visual Function Branch, Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, MD USA
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48
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Tom I, Pham VC, Katschke KJ, Li W, Liang WC, Gutierrez J, Ah Young A, Figueroa I, Eshghi ST, Lee CV, Kanodia J, Snipas SJ, Salvesen GS, Lai P, Honigberg L, van Lookeren Campagne M, Kirchhofer D, Baruch A, Lill JR. Development of a therapeutic anti-HtrA1 antibody and the identification of DKK3 as a pharmacodynamic biomarker in geographic atrophy. Proc Natl Acad Sci U S A 2020; 117:9952-9963. [PMID: 32345717 PMCID: PMC7211935 DOI: 10.1073/pnas.1917608117] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Genetic polymorphisms in the region of the trimeric serine hydrolase high-temperature requirement 1 (HTRA1) are associated with increased risk of age-related macular degeneration (AMD) and disease progression, but the precise biological function of HtrA1 in the eye and its contribution to disease etiologies remain undefined. In this study, we have developed an HtrA1-blocking Fab fragment to test the therapeutic hypothesis that HtrA1 protease activity is involved in the progression of AMD. Next, we generated an activity-based small-molecule probe (ABP) to track target engagement in vivo. In addition, we used N-terminomic proteomic profiling in preclinical models to elucidate the in vivo repertoire of HtrA1-specific substrates, and identified substrates that can serve as robust pharmacodynamic biomarkers of HtrA1 activity. One of these HtrA1 substrates, Dickkopf-related protein 3 (DKK3), was successfully used as a biomarker to demonstrate the inhibition of HtrA1 activity in patients with AMD who were treated with the HtrA1-blocking Fab fragment. This pharmacodynamic biomarker provides important information on HtrA1 activity and pharmacological inhibition within the ocular compartment.
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Affiliation(s)
- Irene Tom
- OMNI Biomarker Development, Genentech, Inc., South San Francisco, CA 94080
| | - Victoria C Pham
- Department of Microchemistry, Proteomics & Lipidomics, Genentech, Inc., South San Francisco, CA 94080
| | - Kenneth J Katschke
- Department of Immunology, Genentech, Inc., South San Francisco, CA 94080
| | - Wei Li
- Department of Early Discovery Biochemistry, Genentech, Inc., South San Francisco, CA 94080
| | - Wei-Ching Liang
- Department of Antibody Discovery, Genentech, Inc., South San Francisco, CA 94080
| | - Johnny Gutierrez
- OMNI Biomarker Development, Genentech, Inc., South San Francisco, CA 94080
| | - Andrew Ah Young
- Department of Early Discovery Biochemistry, Genentech, Inc., South San Francisco, CA 94080
| | - Isabel Figueroa
- Drug Metabolism, Pharmacokinetics, and Bioanalysis, AbbVie, South San Francisco, CA 94090
| | - Shadi Toghi Eshghi
- OMNI Biomarker Development, Genentech, Inc., South San Francisco, CA 94080
| | - ChingWei V Lee
- Biology Core Support, Gilead Sciences, Foster City, CA 94404
| | - Jitendra Kanodia
- Clinical and Translational Pharmacology, Theravance Biopharma, Inc., South San Francisco, CA 94080
| | - Scott J Snipas
- National Cancer Institute-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037
| | - Guy S Salvesen
- National Cancer Institute-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037
| | - Phillip Lai
- Early Clinical Development OMNI Department, Genentech, Inc., South San Francisco, CA 94080
| | - Lee Honigberg
- OMNI Biomarker Development, Genentech, Inc., South San Francisco, CA 94080
| | | | - Daniel Kirchhofer
- Department of Early Discovery Biochemistry, Genentech, Inc., South San Francisco, CA 94080
| | - Amos Baruch
- Biomarker Development, Calico Life Sciences, LLC, South San Francisco, CA 94080
| | - Jennie R Lill
- Department of Microchemistry, Proteomics & Lipidomics, Genentech, Inc., South San Francisco, CA 94080;
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49
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Proteoglycan IMPG2 Shapes the Interphotoreceptor Matrix and Modulates Vision. J Neurosci 2020; 40:4059-4072. [PMID: 32265257 DOI: 10.1523/jneurosci.2994-19.2020] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 01/29/2020] [Accepted: 03/19/2020] [Indexed: 12/13/2022] Open
Abstract
Photoreceptor neurons are surrounded by an extracellular matrix, called the interphotoreceptor matrix (IPM). Activities crucial to vision occur within the IPM, including trafficking of nutrients and metabolites, retinal attachment, and interactions needed for normal outer segment phagocytosis. The IPM includes the following two unique proteoglycans: IPM proteoglycan 1 (IMPG1) and IMPG2. Patients with mutations in IMPG1/IMPG2 develop visual deficits with subretinal material accumulation, highlighting the critical role of the IPM in vision. To determine the role of these proteoglycans in retinal physiology and the pathologic mechanisms that lead to vision loss, we generated mouse models lacking IMPG1/IMPG2. In normal retina, IMPG1 and IMPG2 occupy distinct IPM compartments, represent the main source of chondroitin sulfate and are fundamental for the constitution of the cone-specific glycocalyx stained by the PNA (peanut agglutinin) lectin marker. No evident morphologic or functional deficits were found in mice lacking IMPG1. In the absence of IMPG2, IMPG1 abnormally accumulated at the subretinal space need, likely leading to the formation of subretinal lesions and reduced visual function. Interestingly, mice lacking both IMPG1 and IMPG2, regardless of sex, showed normal retinal structure and function, demonstrating that the aberrant IMPG1 distribution is the main cause of the visual alterations observed in the absence of IMPG2. In conclusion, our results show the dependence of secreted proteoglycans such as IMPG1 on the extracellular environment to properly integrate into the matrix, demonstrate the role of IMPG2 in shaping the IPM, and shed light on the potential mechanisms leading to the development of subretinal lesions and vision loss.SIGNIFICANCE STATEMENT The photoreceptors are specialized neurons that drive phototransduction in the mammalian retina. These cells are organized and surrounded by an extracellular matrix, the interphotoreceptor matrix (IPM). Mutations in IPM proteoglycans are associated with blindness in humans. Our studies show that two specific proteoglycans of the IPM, IPM proteoglycan 1 (IMPG1) and IMPG2, form a dynamic structure with distinct localization and dependency. When IMPG2 is absent, IMPG1 cannot integrate into the IPM, leading to abnormal proteoglycan accumulation and visual deficits. This work adds a new layer of understanding to IPM physiology and describes the pathologic events following deficits in proteoglycans, providing novel possibilities for visual restoration in patients with IMPG-related pathologies.
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50
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Fibulin-7 C-terminal fragment and its active synthetic peptide suppress choroidal and retinal neovascularization. Microvasc Res 2020; 129:103986. [PMID: 32017943 DOI: 10.1016/j.mvr.2020.103986] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 01/13/2020] [Accepted: 02/01/2020] [Indexed: 12/26/2022]
Abstract
Wet age-related macular degeneration (AMD) and diabetic retinopathy are the leading causes of blindness through increased angiogenesis. Although VEGF-neutralizing proteins provide benefit, inconsistent responses indicate a need for new therapies. We previously identified the Fibulin-7 C-terminal fragment (Fbln7-C) as an angiogenesis inhibitor in vitro. Here we show that Fbln7-C inhibits neovascularization in vivo, in both a model of wet AMD involving choroidal neovascularization (CNV) and diabetic retinopathy involving oxygen-induced ischemic retinopathy. Furthermore, a short peptide sequence from Fbln7-C is responsible for the anti-angiogenic properties of Fbln7-C. Our work suggests Fbln7-C as a therapeutic candidate for wet AMD and ischemic retinopathy.
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