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Boccuni I, Bas-Orth C, Bruehl C, Draguhn A, Fairless R. Glutamate transporter contribution to retinal ganglion cell vulnerability in a rat model of multiple sclerosis. Neurobiol Dis 2023; 187:106306. [PMID: 37734623 DOI: 10.1016/j.nbd.2023.106306] [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: 05/19/2023] [Revised: 09/05/2023] [Accepted: 09/18/2023] [Indexed: 09/23/2023] Open
Abstract
Glial glutamate transporters actively participate in neurotransmission and have a fundamental role in determining the ambient glutamate concentration in the extracellular space. Their expression is dynamically regulated in many diseases, including experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis. In EAE, a downregulation has been reported which may render neurons more susceptible to glutamate excitotoxicity. In this study, we have investigated the expression of GLAST (EAAT1) and GLT-1 (EAAT2) in the retina of Brown Norway rats following induction of myelin oligodendrocyte glycoprotein (MOG)-EAE, which results in retinal ganglion cell (RGC) degeneration and dysfunction. In addition, we tested whether AAV-mediated overexpression of GLAST in the retina can protect RGCs from degeneration. To address the impact of glutamate transporter modulation on RGCs, we performed whole-cell recordings and measured tonic NMDA receptor-mediated currents in the absence and presence of a glutamate-uptake blocker. We report that αOFF-RGCs show larger tonic glutamate-induced currents than αON-RGCs, in line with their greater vulnerability under neuroinflammatory conditions. We further show that increased AAV-mediated expression of GLAST in the retina does indeed protect RGCs from degeneration during the inflammatory disease. Collectively, our study highlights the neuroprotective role of glutamate transporters in the EAE retina and provides a characterization of tonic glutamate-currents of αRGCs. The larger effects of increased extracellular glutamate concentration on the αOFF-subtype may underlie its enhanced vulnerability to degeneration.
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Affiliation(s)
- Isabella Boccuni
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg 69120, Germany
| | - Carlos Bas-Orth
- Institute of Anatomy and Cell Biology, University of Heidelberg, Heidelberg 69120, Germany
| | - Claus Bruehl
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg 69120, Germany
| | - Andreas Draguhn
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg 69120, Germany
| | - Richard Fairless
- Department of Neurology, University Clinic Heidelberg, Heidelberg 69120, Germany; Clinical Cooperation Unit (CCU) Neurooncology, German Cancer Consortium (DKTK), German Cancer Research Center (DFKZ), Heidelberg 69120, Germany.
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Ciapă MA, Șalaru DL, Stătescu C, Sascău RA, Bogdănici CM. Optic Neuritis in Multiple Sclerosis—A Review of Molecular Mechanisms Involved in the Degenerative Process. Curr Issues Mol Biol 2022; 44:3959-3979. [PMID: 36135184 PMCID: PMC9497878 DOI: 10.3390/cimb44090272] [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: 07/24/2022] [Revised: 08/29/2022] [Accepted: 08/30/2022] [Indexed: 11/26/2022] Open
Abstract
Multiple sclerosis is a central nervous system inflammatory demyelinating disease with a wide range of clinical symptoms, ocular involvement being frequently marked by the presence of optic neuritis (ON). The emergence and progression of ON in multiple sclerosis is based on various pathophysiological mechanisms, disease progression being secondary to inflammation, demyelination, or axonal degeneration. Early identification of changes associated with axonal degeneration or further investigation of the molecular processes underlying remyelination are current concerns of researchers in the field in view of the associated therapeutic potential. This article aims to review and summarize the scientific literature related to the main molecular mechanisms involved in defining ON as well as to analyze existing data in the literature on remyelination strategies in ON and their impact on long-term prognosis.
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Affiliation(s)
| | - Delia Lidia Șalaru
- Cardiology Clinic, Institute of Cardiovascular Diseases, 700503 Iași, Romania
- Department of Internal Medicine, University of Medicine and Pharmacy “Grigore T. Popa”, 700115 Iași, Romania
- Correspondence:
| | - Cristian Stătescu
- Cardiology Clinic, Institute of Cardiovascular Diseases, 700503 Iași, Romania
- Department of Internal Medicine, University of Medicine and Pharmacy “Grigore T. Popa”, 700115 Iași, Romania
| | - Radu Andy Sascău
- Cardiology Clinic, Institute of Cardiovascular Diseases, 700503 Iași, Romania
- Department of Internal Medicine, University of Medicine and Pharmacy “Grigore T. Popa”, 700115 Iași, Romania
| | - Camelia Margareta Bogdănici
- Department of Surgical Specialties (II), University of Medicine and Pharmacy “Grigore T. Popa”, 700115 Iași, Romania
- Ophthalmology Clinic, Saint Spiridon Hospital, Iași 700111, Romania
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Boccuni I, Fairless R. Retinal Glutamate Neurotransmission: From Physiology to Pathophysiological Mechanisms of Retinal Ganglion Cell Degeneration. Life (Basel) 2022; 12:638. [PMID: 35629305 PMCID: PMC9147752 DOI: 10.3390/life12050638] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 04/22/2022] [Accepted: 04/22/2022] [Indexed: 12/12/2022] Open
Abstract
Glutamate neurotransmission and metabolism are finely modulated by the retinal network, where the efficient processing of visual information is shaped by the differential distribution and composition of glutamate receptors and transporters. However, disturbances in glutamate homeostasis can result in glutamate excitotoxicity, a major initiating factor of common neurodegenerative diseases. Within the retina, glutamate excitotoxicity can impair visual transmission by initiating degeneration of neuronal populations, including retinal ganglion cells (RGCs). The vulnerability of RGCs is observed not just as a result of retinal diseases but has also been ascribed to other common neurodegenerative and peripheral diseases. In this review, we describe the vulnerability of RGCs to glutamate excitotoxicity and the contribution of different glutamate receptors and transporters to this. In particular, we focus on the N-methyl-d-aspartate (NMDA) receptor as the major effector of glutamate-induced mechanisms of neurodegeneration, including impairment of calcium homeostasis, changes in gene expression and signalling, and mitochondrial dysfunction, as well as the role of endoplasmic reticular stress. Due to recent developments in the search for modulators of NMDA receptor signalling, novel neuroprotective strategies may be on the horizon.
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Affiliation(s)
- Isabella Boccuni
- Institute for Physiology and Pathophysiology, Heidelberg University, 69120 Heidelberg, Germany
- Department of Neurology, University Clinic Heidelberg, 69120 Heidelberg, Germany;
| | - Richard Fairless
- Department of Neurology, University Clinic Heidelberg, 69120 Heidelberg, Germany;
- Clinical Cooperation Unit (CCU) Neurooncology, German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
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Chan JS, Nurul-Ain M, Mohamad NF, Wan Hitam WH, Thavaratnam LK. Recurrent Optic Neuritis in Paediatric Anti-N-Methyl-D-Aspartate Receptor (Anti-NMDAR) Encephalitis: Case Report and Literature Review. Neuroophthalmology 2022; 46:258-263. [PMID: 35859635 PMCID: PMC9291683 DOI: 10.1080/01658107.2021.2014892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Optic neuritis associated with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis poses a novel challenge and is recognised as being part of overlapping antibody-associated demyelinating syndromes. We report a case of a 10-year-old girl who first presented with anti-NMDAR encephalitis and later developed four episodes of left optic neuritis. Blurring of vision, pain on eye movement, and headache were the striking features in all episodes of optic neuritis. For each recurrent episode of optic neuritis she was treated with intravenous methylprednisolone, following which visual acuity, colour vision, and visual field improved to normal. Neuroimaging was unremarkable. Myelin oligodendrocyte glycoprotein and aquaporin-4 antibody tests were negative. She developed a relapse of anti-NMDAR encephalitis after recurrent episodes of optic neuritis despite being on azathioprine. Intravenous immunoglobulin and cycles of cyclophosphamide were started, and she has been free from optic neuritis and encephalitis for more than one year since. Optic neuritis and anti-NMDAR encephalitis are reversible with intensive immunotherapy. Early and accurate diagnosis can lead to better management of this condition.
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Affiliation(s)
- Jinn Shian Chan
- UM Eye Research Centre, Department of Ophthalmology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia,Department of Ophthalmology, Hospital Kuala Lumpur, Ministry of Health, Kuala Lumpur, Malaysia
| | - Masnon Nurul-Ain
- Department of Ophthalmology, Hospital Kuala Lumpur, Ministry of Health, Kuala Lumpur, Malaysia,Department of Ophthalmology and Visual Science, School of Medical Sciences, Health Campus, Universiti Sains Malaysia, Kubang Kerian, Malaysia
| | - Nor Fadhilah Mohamad
- UM Eye Research Centre, Department of Ophthalmology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Wan Hazabbah Wan Hitam
- Department of Ophthalmology and Visual Science, School of Medical Sciences, Health Campus, Universiti Sains Malaysia, Kubang Kerian, Malaysia,CONTACT Wan Hazabbah Wan Hitam Department of Ophthalmology and Visual Science, School of Medical Sciences, Health Campus Universiti Sains Malaysia, Kubang KerianMalaysia
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Rosenstein RE. New actors in optic neuritis pathogenesis: An Editorial for "Influence of retinal NMDA receptor activity during autoimmune optic neuritis" on page 693. J Neurochem 2020; 153:671-673. [PMID: 32162696 DOI: 10.1111/jnc.14991] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 02/18/2020] [Accepted: 02/21/2020] [Indexed: 11/30/2022]
Abstract
The aim of the present report was to analyze the involvement of glutamate neurotoxicity in retinal ganglion cell loss and optic nerve damage induced by experimental optic neuritis. For this purpose, the authors used an optic neuritis model induced by immunisation with myelin oligodendrocyte glycoprotein (AON). The authors describe a correlation in the timing of retinal ganglion cell (RGC) loss with alterations in the optic nerve actin cytoskeleton dynamic, and visual dysfunction. In addition, they show that an intravitreal injection of glutamate mimics, and an NMDA receptor antagonist avoids the effect of pre-clinical AON on visual functions and RGC number, as well as on optic nerve actin cytoskeleton. Taken together, their results support that avoiding glutamate neurotoxicity could become a new therapeutic approach for optic neuritis treatment.
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Affiliation(s)
- Ruth E Rosenstein
- Laboratory of Retinal Neurochemistry and Experimental Ophthalmology, Department of Human Biochemistry, School of Medicine/CEFyBO, University of Buenos Aires/CONICET, Buenos Aires, Argentina
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