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Bou Ghanem GO, Wareham LK, Calkins DJ. Addressing neurodegeneration in glaucoma: Mechanisms, challenges, and treatments. Prog Retin Eye Res 2024; 100:101261. [PMID: 38527623 DOI: 10.1016/j.preteyeres.2024.101261] [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: 12/28/2023] [Revised: 03/15/2024] [Accepted: 03/19/2024] [Indexed: 03/27/2024]
Abstract
Glaucoma is the leading cause of irreversible blindness globally. The disease causes vision loss due to neurodegeneration of the retinal ganglion cell (RGC) projection to the brain through the optic nerve. Glaucoma is associated with sensitivity to intraocular pressure (IOP). Thus, mainstay treatments seek to manage IOP, though many patients continue to lose vision. To address neurodegeneration directly, numerous preclinical studies seek to develop protective or reparative therapies that act independently of IOP. These include growth factors, compounds targeting metabolism, anti-inflammatory and antioxidant agents, and neuromodulators. Despite success in experimental models, many of these approaches fail to translate into clinical benefits. Several factors contribute to this challenge. Firstly, the anatomic structure of the optic nerve head differs between rodents, nonhuman primates, and humans. Additionally, animal models do not replicate the complex glaucoma pathophysiology in humans. Therefore, to enhance the success of translating these findings, we propose two approaches. First, thorough evaluation of experimental targets in multiple animal models, including nonhuman primates, should precede clinical trials. Second, we advocate for combination therapy, which involves using multiple agents simultaneously, especially in the early and potentially reversible stages of the disease. These strategies aim to increase the chances of successful neuroprotective treatment for glaucoma.
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Affiliation(s)
- Ghazi O Bou Ghanem
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Lauren K Wareham
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - David J Calkins
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.
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2
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Feng KM, Tsung TH, Chen YH, Lu DW. The Role of Retinal Ganglion Cell Structure and Function in Glaucoma. Cells 2023; 12:2797. [PMID: 38132117 PMCID: PMC10741833 DOI: 10.3390/cells12242797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 11/29/2023] [Accepted: 11/29/2023] [Indexed: 12/23/2023] Open
Abstract
Glaucoma, a leading cause of irreversible blindness globally, primarily affects retinal ganglion cells (RGCs). This review dives into the anatomy of RGC subtypes, covering the different underlying theoretical mechanisms that lead to RGC susceptibility in glaucoma, including mechanical, vascular, excitotoxicity, and neurotrophic factor deficiency, as well as oxidative stress and inflammation. Furthermore, we examined numerous imaging methods and functional assessments to gain insight into RGC health. Finally, we investigated the current possible neuroprotective targets for RGCs that could help with future glaucoma research and management.
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Affiliation(s)
| | | | | | - Da-Wen Lu
- Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei 11490, Taiwan; (K.M.F.); (T.-H.T.); (Y.-H.C.)
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3
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Chiarugi A. Glaucoma: neuroprotection with NAD-based therapeutic interventions. Trends Pharmacol Sci 2023; 44:869-879. [PMID: 37880000 DOI: 10.1016/j.tips.2023.09.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 09/22/2023] [Accepted: 09/26/2023] [Indexed: 10/27/2023]
Abstract
Clinical evidence shows that intraocular hypertension is not the primary pathogenetic event of glaucoma, whereas early neurodegeneration of retinal ganglion cells (RGCs) represents a key therapeutic target. Unfortunately, failure of clinical trials with neuroprotective agents, in particular those testing the anti-excitotoxic drug memantine, generated widespread skepticism regarding the possibility of counteracting neurodegeneration during glaucoma. New avenues for neuroprotective approaches to counteract glaucoma evolution have been opened by the identification of a programmed axonal degeneration (PAD) program triggered by increased nicotinamide mononucleotide (NMN)/NAD concentration ratio. Positive results of proof-of-concept clinical studies based on sustaining axonal NAD homeostasis facilitated the design of Phase 2/3 trials. Here, I share my opinion on how neurodegeneration in glaucoma should be put into context, together with an appraisal of the pharmacological rationale of NAD-supporting therapies for use during glaucoma progression.
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Affiliation(s)
- Alberto Chiarugi
- Section of Clinical Pharmacology and Oncology, Department of Health Sciences, University of Florence, Florence, Italy; Headache Center and Clinical Pharmacology Unit, Careggi University Hospital, Florence, Italy.
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4
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Zhao WJ, Fan CL, Hu XM, Ban XX, Wan H, He Y, Zhang Q, Xiong K. Regulated Cell Death of Retinal Ganglion Cells in Glaucoma: Molecular Insights and Therapeutic Potentials. Cell Mol Neurobiol 2023; 43:3161-3178. [PMID: 37338781 DOI: 10.1007/s10571-023-01373-1] [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: 01/19/2023] [Accepted: 06/05/2023] [Indexed: 06/21/2023]
Abstract
Glaucoma is a group of diseases characterized by the degeneration of retinal ganglion cells (RGCs) and progressive, irreversible vision loss. High intraocular pressure (IOP) heightens the likelihood of glaucoma and correlates with RGC loss. While the current glaucoma therapy prioritizes lower the IOP; however, RGC, and visual loss may persist even when the IOP is well-controlled. As such, discovering and creating IOP-independent neuroprotective strategies for safeguard RGCs is crucial for glaucoma management. Investigating and clarifying the mechanism behind RGC death to counteract its effects is a promising direction for glaucoma control. Empirical studies of glaucoma reveal the role of multiple regulated cell death (RCD) pathways in RGC death. This review delineates the RCD of RGCs following IOP elevation and optic nerve damage and discusses the substantial benefits of mitigating RCD in RGCs in preserving visual function.
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Affiliation(s)
- Wen-Juan Zhao
- Department of Human Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Hunan Province, No. 172, Tongzipo Road, Yuelu District, Changsha City, 410013, China
| | - Chun-Ling Fan
- Department of Human Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Hunan Province, No. 172, Tongzipo Road, Yuelu District, Changsha City, 410013, China
| | - Xi-Min Hu
- Department of Dermatology, Xiangya Hospital, Central South University, Hunan Province, No. 172, Tongzipo Road, Yuelu District, Changsha City, 410013, China
| | - Xiao-Xia Ban
- Department of Human Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Hunan Province, No. 172, Tongzipo Road, Yuelu District, Changsha City, 410013, China
| | - Hao Wan
- Department of Human Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Hunan Province, No. 172, Tongzipo Road, Yuelu District, Changsha City, 410013, China
| | - Ye He
- Changsha Aier Eye Hospital, Hunan Province, No. 188, Furong Road, Furong District, Changsha City, 410015, China
| | - Qi Zhang
- Department of Human Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Hunan Province, No. 172, Tongzipo Road, Yuelu District, Changsha City, 410013, China.
- Key Laboratory of Emergency and Trauma of Ministry of Education, Hainan Medical University, Haikou, 571199, China.
| | - Kun Xiong
- Department of Human Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Hunan Province, No. 172, Tongzipo Road, Yuelu District, Changsha City, 410013, China.
- Key Laboratory of Emergency and Trauma of Ministry of Education, Hainan Medical University, Haikou, 571199, China.
- Hunan Key Laboratory of Ophthalmology, Changsha, 410013, China.
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5
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Gherghel D, De Moraes G. Barriers to IOP-independent treatments in glaucoma clinical trials. Eye (Lond) 2023; 37:1955-1957. [PMID: 36400853 PMCID: PMC10333330 DOI: 10.1038/s41433-022-02305-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 10/31/2022] [Accepted: 10/31/2022] [Indexed: 11/19/2022] Open
Affiliation(s)
- Doina Gherghel
- College of Health and Life Sciences, Vascular Research Laboratory, Aston University, Birmingham, UK.
- Division of Cardiovascular Sciences, Manchester University, Manchester, UK.
| | - Gustavo De Moraes
- Bernard and Shirlee Brown Glaucoma Research Laboratory, Department of Ophthalmology, Columbia University Irving Medical Center, New York City, NY, USA
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6
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Miao Y, Zhao GL, Cheng S, Wang Z, Yang XL. Activation of retinal glial cells contributes to the degeneration of ganglion cells in experimental glaucoma. Prog Retin Eye Res 2023; 93:101169. [PMID: 36736070 DOI: 10.1016/j.preteyeres.2023.101169] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 01/12/2023] [Accepted: 01/24/2023] [Indexed: 02/04/2023]
Abstract
Elevation of intraocular pressure (IOP) is a major risk factor for neurodegeneration in glaucoma. Glial cells, which play an important role in normal functioning of retinal neurons, are well involved into retinal ganglion cell (RGC) degeneration in experimental glaucoma animal models generated by elevated IOP. In response to elevated IOP, mGluR I is first activated and Kir4.1 channels are subsequently inhibited, which leads to the activation of Müller cells. Müller cell activation is followed by a complex process, including proliferation, release of inflammatory and growth factors (gliosis). Gliosis is further regulated by several factors. Activated Müller cells contribute to RGC degeneration through generating glutamate receptor-mediated excitotoxicity, releasing cytotoxic factors and inducing microglia activation. Elevated IOP activates microglia, and following morphological and functional changes, these cells, as resident immune cells in the retina, show adaptive immune responses, including an enhanced release of pro-inflammatory factors (tumor neurosis factor-α, interleukins, etc.). These ATP and Toll-like receptor-mediated responses are further regulated by heat shock proteins, CD200R, chemokine receptors, and metabotropic purinergic receptors, may aggravate RGC loss. In the optic nerve head, astrogliosis is initiated and regulated by a complex reaction process, including purines, transmitters, chemokines, growth factors and cytokines, which contributes to RGC axon injury through releasing pro-inflammatory factors and changing extracellular matrix in glaucoma. The effects of activated glial cells on RGCs are further modified by the interplay among different types of glial cells. This review is concluded by presenting an in-depth discussion of possible research directions in this field in the future.
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Affiliation(s)
- Yanying Miao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Guo-Li Zhao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Shuo Cheng
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Zhongfeng Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China.
| | - Xiong-Li Yang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China.
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7
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Kuo CY, Liu CJL. Neuroprotection in Glaucoma: Basic Aspects and Clinical Relevance. J Pers Med 2022; 12:jpm12111884. [PMID: 36579616 PMCID: PMC9697907 DOI: 10.3390/jpm12111884] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 10/21/2022] [Accepted: 11/04/2022] [Indexed: 11/12/2022] Open
Abstract
Glaucoma is a neurodegenerative disease that affects primarily the retinal ganglion cells (RGCs). Increased intraocular pressure (IOP) is one of the major risk factors for glaucoma. The mainstay of current glaucoma therapy is limited to lowering IOP; however, controlling IOP in certain patients can be futile in slowing disease progression. The understanding of potential biomolecular processes that occur in glaucomatous degeneration allows for the development of glaucoma treatments that modulate the death of RGCs. Neuroprotection is the modification of RGCs and the microenvironment of neurons to promote neuron survival and function. Numerous studies have revealed effective neuroprotection modalities in animal models of glaucoma; nevertheless, clinical translation remains a major challenge. In this review, we select the most clinically relevant treatment strategies, summarize preclinical and clinical data as well as recent therapeutic advances in IOP-independent neuroprotection research, and discuss the feasibility and hurdles of each therapeutic approach based on possible pathogenic mechanisms. We also summarize the potential therapeutic mechanisms of various agents in neuroprotection related to glutamate excitotoxicity.
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Affiliation(s)
- Che-Yuan Kuo
- Department of Ophthalmology, Taipei Veterans General Hospital, Taipei 11217, Taiwan
| | - Catherine Jui-Ling Liu
- Department of Ophthalmology, Taipei Veterans General Hospital, Taipei 11217, Taiwan
- Faculty of Medicine, School of Medicine, National Yang Ming Chiao Tung University, Taipei 11221, Taiwan
- Correspondence: ; Tel.: +886-2-2875-7325
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8
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Shinozaki Y, Leung A, Namekata K, Saitoh S, Nguyen HB, Takeda A, Danjo Y, Morizawa YM, Shigetomi E, Sano F, Yoshioka N, Takebayashi H, Ohno N, Segawa T, Miyake K, Kashiwagi K, Harada T, Ohnuma SI, Koizumi S. Astrocytic dysfunction induced by ABCA1 deficiency causes optic neuropathy. SCIENCE ADVANCES 2022; 8:eabq1081. [PMID: 36332025 PMCID: PMC9635836 DOI: 10.1126/sciadv.abq1081] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
Astrocyte abnormalities have received great attention for their association with various diseases in the brain but not so much in the eye. Recent independent genome-wide association studies of glaucoma, optic neuropathy characterized by retinal ganglion cell (RGC) degeneration, and vision loss found that single-nucleotide polymorphisms near the ABCA1 locus were common risk factors. Here, we show that Abca1 loss in retinal astrocytes causes glaucoma-like optic neuropathy in aged mice. ABCA1 was highly expressed in retinal astrocytes in mice. Thus, we generated macroglia-specific Abca1-deficient mice (Glia-KO) and found that aged Glia-KO mice had RGC degeneration and ocular dysfunction without affected intraocular pressure, a conventional risk factor for glaucoma. Single-cell RNA sequencing revealed that Abca1 deficiency in aged Glia-KO mice caused astrocyte-triggered inflammation and increased the susceptibility of certain RGC clusters to excitotoxicity. Together, astrocytes play a pivotal role in eye diseases, and loss of ABCA1 in astrocytes causes glaucoma-like neuropathy.
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Affiliation(s)
- Youichi Shinozaki
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
- GLIA Center, University of Yamanashi, Yamanashi, Japan
| | - Alex Leung
- UCL Institute of Ophthalmology, University College London, London, UK
| | - Kazuhiko Namekata
- Visual Research Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Sei Saitoh
- Section of Electron Microscopy, Supportive Center for Brain Research, National Institute for Physiological Sciences (NIPS), Aichi, Japan
- Department of Anatomy II and Cell Biology, Fujita Health University School of Medicine, Aichi, Japan
| | - Huy Bang Nguyen
- Division of Neurobiology and Bioinformatics, NIPS, Aichi, Japan
- Department of Anatomy, Faculty of Medicine, University of Medicine and Pharmacy (UMP), Ho Chi Minh City, Vietnam
| | - Akiko Takeda
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Yosuke Danjo
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Yosuke M. Morizawa
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Eiji Shigetomi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
- GLIA Center, University of Yamanashi, Yamanashi, Japan
| | - Fumikazu Sano
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Nozomu Yoshioka
- Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Hirohide Takebayashi
- Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Nobuhiko Ohno
- Division of Ultrastructural Research, NIPS, Aichi, Japan
- Department of Anatomy, Jichi Medical University, Tochigi, Japan
| | - Takahiro Segawa
- Center for Life Science Research, University of Yamanashi, Yamanashi, Japan
| | - Kunio Miyake
- Department of Health Sciences, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Kenji Kashiwagi
- Department of Ophthalmology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Takayuki Harada
- Visual Research Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Shin-ichi Ohnuma
- UCL Institute of Ophthalmology, University College London, London, UK
| | - Schuichi Koizumi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
- GLIA Center, University of Yamanashi, Yamanashi, Japan
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9
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Levin LA, Patrick C, Choudry NB, Sharif NA, Goldberg JL. Neuroprotection in neurodegenerations of the brain and eye: Lessons from the past and directions for the future. Front Neurol 2022; 13:964197. [PMID: 36034312 PMCID: PMC9412944 DOI: 10.3389/fneur.2022.964197] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 07/20/2022] [Indexed: 12/24/2022] Open
Abstract
BackgroundNeurological and ophthalmological neurodegenerative diseases in large part share underlying biology and pathophysiology. Despite extensive preclinical research on neuroprotection that in many cases bridges and unifies both fields, only a handful of neuroprotective therapies have succeeded clinically in either.Main bodyUnderstanding the commonalities among brain and neuroretinal neurodegenerations can help develop innovative ways to improve translational success in neuroprotection research and emerging therapies. To do this, analysis of why translational research in neuroprotection fails necessitates addressing roadblocks at basic research and clinical trial levels. These include optimizing translational approaches with respect to biomarkers, therapeutic targets, treatments, animal models, and regulatory pathways.ConclusionThe common features of neurological and ophthalmological neurodegenerations are useful for outlining a path forward that should increase the likelihood of translational success in neuroprotective therapies.
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Affiliation(s)
- Leonard A. Levin
- Departments of Ophthalmology and Visual Sciences, Neurology & Neurosurgery, McGill University, Montreal, QC, Canada
- *Correspondence: Leonard A. Levin
| | | | - Nozhat B. Choudry
- Global Alliances and External Research, Ophthalmology Innovation Center, Santen Inc., Emeryville, CA, United States
| | - Najam A. Sharif
- Global Alliances and External Research, Ophthalmology Innovation Center, Santen Inc., Emeryville, CA, United States
| | - Jeffrey L. Goldberg
- Spencer Center for Vision Research, Byers Eye Institute, Stanford University, Palo Alto, CA, United States
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10
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Trans-synaptic degeneration in the visual pathway: Neural connectivity, pathophysiology, and clinical implications in neurodegenerative disorders. Surv Ophthalmol 2021; 67:411-426. [PMID: 34146577 DOI: 10.1016/j.survophthal.2021.06.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 06/06/2021] [Accepted: 06/07/2021] [Indexed: 12/13/2022]
Abstract
There is a strong interrelationship between eye and brain diseases. It has been shown that neurodegenerative changes can spread bidirectionally in the visual pathway along neuronal projections. For example, damage to retinal ganglion cells in the retina leads to degeneration of the visual cortex (anterograde degeneration) and vice versa (retrograde degeneration). The underlying mechanisms of this process, known as trans-synaptic degeneration (TSD), are unknown, but TSD contributes to the progression of numerous neurodegenerative disorders, leading to clinical and functional deterioration. The hierarchical structure of the visual system comprises of a strong topographic connectivity between the retina and the visual cortex and therefore serves as an ideal model to study the cellular effect, clinical manifestations, and deterioration extent of TSD. With this review we provide comprehensive information about the neural connectivity, synapse function, molecular changes, and pathophysiology of TSD in visual pathways. We then discuss its bidirectional nature and clinical implications in neurodegenerative diseases. A thorough understanding of TSD in the visual pathway can provide insights into progression of neurodegenerative disorders and its potential as a therapeutic target.
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11
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Kompella UB, Hartman RR, Patil MA. Extraocular, periocular, and intraocular routes for sustained drug delivery for glaucoma. Prog Retin Eye Res 2021; 82:100901. [PMID: 32891866 PMCID: PMC8317199 DOI: 10.1016/j.preteyeres.2020.100901] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 08/22/2020] [Accepted: 08/30/2020] [Indexed: 02/07/2023]
Abstract
Although once daily anti-glaucoma drug therapy is a current clinical reality, most therapies require multiple dosing and there is an unmet need to develop convenient, safe, and effective sustained release drug delivery systems for long-term treatment to improve patient adherence and outcomes. One of the first sustained release drug delivery systems was approved for the reduction of intraocular pressure in glaucoma patients. It is a polymeric reservoir-type insert delivery system, Ocusert™, placed under the eyelid and on the ocular surface for zero-order drug release over one week. The insert, marketed in two strengths, released pilocarpine on the eye surface. While many clinicians appreciated this drug product, it was eventually discontinued. No similar sustained release non-invasive drug delivery system has made it to the market to date for treating glaucoma. Drug delivery systems under development include punctal plugs, ring-type systems, contact lenses, implants, microspheres, nanospheres, gels, and other depot systems placed in the extraocular, periocular, or intraocular regions including intracameral, supraciliary, and intravitreal spaces. This article discusses the advantages and disadvantages of the various routes of administration and delivery systems for sustained glaucoma therapy. It also provides the reader with some examples and discussion of drug delivery systems that could potentially be applied for glaucoma treatment. Interestingly, one intracamerally injected implant, Durysta™, was approved recently for sustained intraocular pressure reduction. However, long-term acceptance of such devices has yet to be established. The ultimate success of the delivery system will depend on efficacy relative to eye drop dosing, safety, reimbursement options, and patient acceptance. Cautious development efforts are warranted considering prior failed approaches for sustained glaucoma drug delivery. Neuroprotective approaches for glaucoma therapy including cell, gene, protein, and drug-combination therapies, mostly administered intravitreally, are also rapidly progressing towards assessment in humans.
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Affiliation(s)
- Uday B Kompella
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Ophthalmology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Colorado Center for Nanomedicine and Nanosafety, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
| | - Rachel R Hartman
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Madhoosudan A Patil
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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12
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Takahashi N, Matsunaga N, Natsume T, Kitazawa C, Itani Y, Hama A, Hayashi I, Shimazawa M, Hara H, Takamatsu H. A longitudinal comparison in cynomolgus macaques of the effect of brimonidine on optic nerve neuropathy using diffusion tensor imaging magnetic resonance imaging and spectral domain optical coherence tomography. Heliyon 2021; 7:e06701. [PMID: 33898826 PMCID: PMC8056221 DOI: 10.1016/j.heliyon.2021.e06701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 01/04/2021] [Accepted: 03/31/2021] [Indexed: 10/26/2022] Open
Abstract
Early detection of optic neuropathy is crucial for initiating treatment that could delay or prevent visual field loss. Preclinical studies have advanced a number of potential neuroprotective strategies to prevent retinal ganglion cell (RGC) degeneration, but none have successfully completed clinical trials. One issue related to the lack of preclinical to clinical translation is the lack of preclinical morphometric assessments that could be used to track neuroprotection, as well as neurodegeneration, over time within the same animal. Thus, to assess whether clinically used morphometric assessments can identify neuroprotection of RGC, the current study compared optic nerve fractional anisotropy (FA) obtained with diffusion tensor imaging (DTI) and retinal nerve fiber layer (RNFL) thickness measured with spectral domain optical coherence tomography (SD-OCT) to observe not only the early progression of RGC axonal degeneration but to also discern which imaging modality identifies signs of neuroprotection during treatment with the alpha-adrenoceptor agonist brimonidine. Elevated and sustained intraocular pressure (IOP) was observed following laser photocoagulation of the trabecular meshwork in one eye of nonhuman primates (NHP). Either brimonidine (0.1%) or control treatment was instilled twice daily for two months. In control-treated eyes, increased IOP, increased vertical cup-to-disc (C/D), reduced rim-to-disc (R/D) ratio, decreased RNFL thickness and decreased FA were observed. While IOP remained elevated during the course of the study, brimonidine tended to delay the progression of RNFL thinning. However, in the same animal, optic nerve FA did not appear to decline. Brimonidine treatment did not affect other measures of RGC axonal degeneration. The current findings demonstrate that early progression of optic neuropathy can be tracked over time in a nonhuman primate model of ocular hypertension using either DTI or SD-OCT. Furthermore, the delayed changes to RNFL thickness and FA appear to be a neuroprotective effect of brimonidine independent of its effect on IOP.
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Affiliation(s)
- Nobuyuki Takahashi
- Pharmacology, Hamamatsu Pharma Research, Inc., 1-3-7, Shinmiyakoda, Kita-ku, Hamamatsu, Shizuoka, 431-2103, Japan
| | - Naoko Matsunaga
- Pharmacology, Hamamatsu Pharma Research, Inc., 1-3-7, Shinmiyakoda, Kita-ku, Hamamatsu, Shizuoka, 431-2103, Japan
| | - Takahiro Natsume
- Pharmacology, Hamamatsu Pharma Research, Inc., 1-3-7, Shinmiyakoda, Kita-ku, Hamamatsu, Shizuoka, 431-2103, Japan
| | - Chinatsu Kitazawa
- Pharmacology, Hamamatsu Pharma Research, Inc., 1-3-7, Shinmiyakoda, Kita-ku, Hamamatsu, Shizuoka, 431-2103, Japan
| | - Yoshitaka Itani
- Pharmacology, Hamamatsu Pharma Research, Inc., 1-3-7, Shinmiyakoda, Kita-ku, Hamamatsu, Shizuoka, 431-2103, Japan
| | - Aldric Hama
- Pharmacology, Hamamatsu Pharma Research, Inc., 1-3-7, Shinmiyakoda, Kita-ku, Hamamatsu, Shizuoka, 431-2103, Japan
| | - Ikuo Hayashi
- Hamamatsu Pharma Research USA, Inc., 4660 La Jolla Village Drive, San Diego, CA, 92122 USA
| | - Masamitsu Shimazawa
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan
| | - Hideaki Hara
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan
| | - Hiroyuki Takamatsu
- Pharmacology, Hamamatsu Pharma Research, Inc., 1-3-7, Shinmiyakoda, Kita-ku, Hamamatsu, Shizuoka, 431-2103, Japan
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New perspectives of immunomodulation and neuroprotection in glaucoma. Cent Eur J Immunol 2021; 46:105-110. [PMID: 33897291 PMCID: PMC8056344 DOI: 10.5114/ceji.2021.104329] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 09/21/2020] [Indexed: 02/07/2023] Open
Abstract
Glaucoma is the neurodegenerative disease of retinal ganglion cells. The main risk factor for glaucoma is increased intraocular pressure. The processes leading to cell death due to presence of the injury factor comprise multiple molecular mechanisms, as well as the immunological response. The knowledge of immunological mechanisms occurring in glaucomatous degeneration makes it possible to introduce glaucoma treatment modulating the cellular degradation. The glaucoma treatment of the future will make it possible not only to lower the intraocular pressure, but also to moderate the intracellular mechanisms in order to prevent retinal cell degeneration. Citicoline is a drug modulating glutamate excitotoxicity that is already in use. Rho kinase inhibitors were found to stimulate neurite growth and axon regeneration apart from lowering intraocular pressure. The complementary action of brimonidine is to increase neurotrophic factor (NTF) concentrations and inhibit glutamate toxicity. Immunomodulatory therapies with antibodies and gene therapies show promising effects in the current studies. The supplementation of NTFs prevents glaucomatous damage. Resveratrol and other antioxidants inhibit reactive oxygen species formation. Cell transplantation of stem cells, Schwann cells and nerve extracts was reported to be successful so far. Our review presents the most promising new strategies of neuroprotection and immunomodulation in glaucoma.
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Hopper RG, Montiani-Ferreira F, da Silva Pereira J, Fritz MC, Ruggiero VJ, Sapienza JS, Kato K, Komáromy AM. Presumed neuroprotective therapies prescribed by veterinary ophthalmologists for canine degenerative retinal and optic nerve diseases. Vet Ophthalmol 2021; 24:229-239. [PMID: 33682296 DOI: 10.1111/vop.12878] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 02/13/2021] [Accepted: 02/13/2021] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To investigate veterinary ophthalmologists' use of presumed neuroprotective therapies for degenerative retinal and optic nerve diseases in dogs. PROCEDURES An online survey was sent to 663 board-certified veterinary ophthalmologists who were Diplomates of the American College of Veterinary Ophthalmologists (ACVO), Asian College of Veterinary Ophthalmologists (AiCVO), Latin American College of Veterinary Ophthalmologists (Colegio Latinoamericano de Oftalmólogos Veterinarios, CLOVE), or European College of Veterinary Ophthalmologists (ECVO). The survey was created using Qualtrics® software and focused on the prescription of presumed neuroprotective treatments for canine glaucoma, sudden acquired retinal degeneration syndrome (SARDS), progressive retinal atrophy (PRA), and retinal detachment (RD). RESULTS A total of 165 completed surveys were received, representing an overall response rate of 25%, which was comparable across the four specialty colleges. Of all respondents, 140/165 (85%) prescribed some form of presumed neuroprotective therapies at least once in the last five years: 114/165 (69%) for glaucoma, 51/165 (31%) for SARDS, 116/165 (70%) for PRA, and 50/165 (30%) for RD. The three most recommended neuroprotective reagents were the commercial Ocu-GLO™ Vision Supplement for animals, amlodipine, and human eye supplements. CONCLUSIONS Despite lack of published clinical efficacy data, the majority of surveyed board-certified veterinary ophthalmologists previously prescribed a presumed neuroprotective therapy at least once in the last five years in dogs with degenerative retinal and optic nerve diseases.
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Affiliation(s)
- Ryan G Hopper
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
| | | | - Jorge da Silva Pereira
- Center of Studies, Research, and Veterinary Ophthalmology (CEPOV), Rio de Janeiro, Brazil
| | - Michele C Fritz
- Office of Academic Programs, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
| | - Vickie J Ruggiero
- Office of Academic Programs, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
| | | | | | - András M Komáromy
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
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Komáromy AM, Koehl KL, Park SA. Looking into the future: Gene and cell therapies for glaucoma. Vet Ophthalmol 2021; 24 Suppl 1:16-33. [PMID: 33411993 PMCID: PMC7979454 DOI: 10.1111/vop.12858] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 12/21/2020] [Indexed: 12/17/2022]
Abstract
Glaucoma is a complex group of optic neuropathies that affects both humans and animals. Intraocular pressure (IOP) elevation is a major risk factor that results in the loss of retinal ganglion cells (RGCs) and their axons. Currently, lowering IOP by medical and surgical methods is the only approved treatment for primary glaucoma, but there is no cure, and vision loss often progresses despite therapy. Recent technologic advances provide us with a better understanding of disease mechanisms and risk factors; this will permit earlier diagnosis of glaucoma and initiation of therapy sooner and more effectively. Gene and cell therapies are well suited to target these mechanisms specifically with the potential to achieve a lasting therapeutic effect. Much progress has been made in laboratory settings to develop these novel therapies for the eye. Gene and cell therapies have already been translated into clinical application for some inherited retinal dystrophies and age-related macular degeneration (AMD). Except for the intravitreal application of ciliary neurotrophic factor (CNTF) by encapsulated cell technology for RGC neuroprotection, there has been no other clinical translation of gene and cell therapies for glaucoma so far. Possible application of gene and cell therapies consists of long-term IOP control via increased aqueous humor drainage, including inhibition of fibrosis following filtration surgery, RGC neuroprotection and neuroregeneration, modification of ocular biomechanics for improved IOP tolerance, and inhibition of inflammation and neovascularization to prevent the development of some forms of secondary glaucoma.
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Affiliation(s)
- András M. Komáromy
- College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
| | - Kristin L. Koehl
- College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
| | - Shin Ae Park
- College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
- College of Veterinary Medicine, Purdue University, West Lafayette, IN, USA
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Rahić O, Tucak A, Omerović N, Sirbubalo M, Hindija L, Hadžiabdić J, Vranić E. Novel Drug Delivery Systems Fighting Glaucoma: Formulation Obstacles and Solutions. Pharmaceutics 2020; 13:E28. [PMID: 33375224 PMCID: PMC7824381 DOI: 10.3390/pharmaceutics13010028] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 12/19/2020] [Accepted: 12/22/2020] [Indexed: 02/06/2023] Open
Abstract
Glaucoma is considered to be one of the biggest health problems in the world. It is the main cause of preventable blindness due to its asymptomatic nature in the early stages on the one hand and patients' non-adherence on the other. There are several approaches in glaucoma treatment, whereby this has to be individually designed for each patient. The first-line treatment is medication therapy. However, taking into account numerous disadvantages of conventional ophthalmic dosage forms, intensive work has been carried out on the development of novel drug delivery systems for glaucoma. This review aims to provide an overview of formulation solutions and strategies in the development of in situ gel systems, nanosystems, ocular inserts, contact lenses, collagen corneal shields, ocular implants, microneedles, and iontophoretic devices. The results of studies confirming the effectiveness of the aforementioned drug delivery systems were also briefly presented.
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Affiliation(s)
- Ognjenka Rahić
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Sarajevo, Zmaja od Bosne 8, 71000 Sarajevo, Bosnia and Herzegovina; (A.T.); (M.S.); (L.H.); (J.H.)
| | - Amina Tucak
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Sarajevo, Zmaja od Bosne 8, 71000 Sarajevo, Bosnia and Herzegovina; (A.T.); (M.S.); (L.H.); (J.H.)
| | - Naida Omerović
- Department of Clinical Pharmacy, Faculty of Pharmacy, University of Sarajevo, Zmaja od Bosne 8, 71000 Sarajevo, Bosnia and Herzegovina;
| | - Merima Sirbubalo
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Sarajevo, Zmaja od Bosne 8, 71000 Sarajevo, Bosnia and Herzegovina; (A.T.); (M.S.); (L.H.); (J.H.)
| | - Lamija Hindija
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Sarajevo, Zmaja od Bosne 8, 71000 Sarajevo, Bosnia and Herzegovina; (A.T.); (M.S.); (L.H.); (J.H.)
| | - Jasmina Hadžiabdić
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Sarajevo, Zmaja od Bosne 8, 71000 Sarajevo, Bosnia and Herzegovina; (A.T.); (M.S.); (L.H.); (J.H.)
| | - Edina Vranić
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Sarajevo, Zmaja od Bosne 8, 71000 Sarajevo, Bosnia and Herzegovina; (A.T.); (M.S.); (L.H.); (J.H.)
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17
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Plummer CE, Bras D, Grozdanic S, Komáromy AM, McLellan G, Miller P, Sapienza JS, Teixeira L, Webb T. Prophylactic anti-glaucoma therapy in dogs with primary glaucoma: A practitioner survey of current medical protocols. Vet Ophthalmol 2020; 24 Suppl 1:96-108. [PMID: 32920915 DOI: 10.1111/vop.12820] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 07/30/2020] [Accepted: 08/06/2020] [Indexed: 12/17/2022]
Abstract
AIM To examine the use of prophylactic anti-glaucoma medications in the normotensive fellow eye in dogs with unilateral overt primary glaucoma by veterinary ophthalmology clinicians. METHODS A survey of veterinary ophthalmology clinicians was distributed over two international list serves servicing veterinary ophthalmologists, trainees, and individuals whose practice consisted primarily of ophthalmic patients. The survey was developed following analysis of historical and currently available medical options for control of intraocular pressure and for neuroprotection. RESULTS Responses from 199 veterinary ophthalmology clinicians were evaluated. While a large variety of topical anti-hypertensive drugs and protocols were used, the most commonly used medications were aqueous humor production suppressors such as dorzolamide 2.0% ophthalmic solution, timolol 0.5% ophthalmic solution, and a combination product containing both drugs. Latanoprost 0.005% ophthalmic solution was used infrequently for prophylaxis by comparison. The majority of respondents do not use concurrent anti-inflammatory medications (61.22%), although a sizeable minority used prednisolone acetate, dexamethasone, or ketorolac as prophylactic treatment. Systemically administered ocular anti-hypertensive agents were rarely used. Only 40% of respondents used neuroprotectant agents; the most commonly prescribed were the calcium channel blocker amlodipine and the nutraceutical Ocu-Glo™. Recommended intervals between re-examination by the clinician ranged from one month to one year, with most re-evaluations occurring every 3 to 6 months. The majority of respondents recommended more frequent assessments of IOP at intervals between once monthly and once every 3 months. CONCLUSIONS Data analysis of medical therapy for the normotensive fellow eye of dogs previously diagnosed with primary glaucoma suggests that there is a great need for well-designed, prospective, controlled, multi-center studies to determine which protocols have the greatest efficacy in delaying an overt attack in the previously normotensive eye in dogs with a genetic predisposition to glaucoma. Prospective studies utilizing a carbonic anhydrase inhibitor such as dorzolamide and a prostaglandin analogue such as latanoprost would be reasonable as these two drugs are widely used in the treatment of overt glaucoma and would allow for an exploration of the impact of different mechanisms of action of lowering IOP on the pathophysiology of primary glaucoma.
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Affiliation(s)
- Caryn E Plummer
- College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - Dineli Bras
- Centro de Especialistas Veterinarios de Puerto Rico, San Juan, PR, USA
| | | | - András M Komáromy
- College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
| | - Gillian McLellan
- School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Paul Miller
- School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | | | - Leandro Teixeira
- School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Terah Webb
- MedVet Medical & Cancer Centers for Pets, Worthington, OH, USA
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Oxidative Stress and Vascular Dysfunction in the Retina: Therapeutic Strategies. Antioxidants (Basel) 2020; 9:antiox9080761. [PMID: 32824523 PMCID: PMC7465265 DOI: 10.3390/antiox9080761] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/11/2020] [Accepted: 08/14/2020] [Indexed: 12/14/2022] Open
Abstract
Many retinal diseases, such as diabetic retinopathy, glaucoma, and age-related macular (AMD) degeneration, are associated with elevated reactive oxygen species (ROS) levels. ROS are important intracellular signaling molecules that regulate numerous physiological actions, including vascular reactivity and neuron function. However, excessive ROS formation has been linked to vascular endothelial dysfunction, neuron degeneration, and inflammation in the retina. ROS can directly modify cellular molecules and impair their function. Moreover, ROS can stimulate the production of inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) causing inflammation and cell death. However, there are various compounds with direct or indirect antioxidant activity that have been used to reduce ROS accumulation in animal models and humans. In this review, we report on the physiological and pathophysiological role of ROS in the retina with a special focus on the vascular system. Moreover, we present therapeutic approaches for individual retinal diseases targeting retinal signaling pathways involving ROS.
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Current Medical Therapy and Future Trends in the Management of Glaucoma Treatment. J Ophthalmol 2020; 2020:6138132. [PMID: 32774906 PMCID: PMC7391108 DOI: 10.1155/2020/6138132] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 06/29/2020] [Indexed: 01/02/2023] Open
Abstract
Glaucoma is a neurodegenerative disease characterized by progressive loss of retinal ganglion cells and their axons. Lowering of intraocular pressure (IOP) is currently the only proven treatment strategy for glaucoma. However, some patients show progressive loss of visual field and quality of life despite controlled IOP which indicates that other factors are implicated in glaucoma. Therefore, approaches that could prevent or decrease the rate of progression and do not rely on IOP lowering have gained much attention. Effective neuroprotection has been reported in animal models of glaucoma, but till now, no neuroprotective agents have been clinically approved. The present update provides an overview of currently available IOP-lowering medications. Moreover, potential new treatment targets for IOP-lowering and neuroprotective therapy are discussed. Finally, future trends in glaucoma therapy are addressed, including sustained drug delivery systems and progress toward personalized medicine.
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20
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Neuroprotective Strategies for Retinal Ganglion Cell Degeneration: Current Status and Challenges Ahead. Int J Mol Sci 2020; 21:ijms21072262. [PMID: 32218163 PMCID: PMC7177277 DOI: 10.3390/ijms21072262] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/19/2020] [Accepted: 03/20/2020] [Indexed: 12/12/2022] Open
Abstract
The retinal ganglion cells (RGCs) are the output cells of the retina into the brain. In mammals, these cells are not able to regenerate their axons after optic nerve injury, leaving the patients with optic neuropathies with permanent visual loss. An effective RGCs-directed therapy could provide a beneficial effect to prevent the progression of the disease. Axonal injury leads to the functional loss of RGCs and subsequently induces neuronal death, and axonal regeneration would be essential to restore the neuronal connectivity, and to reestablish the function of the visual system. The manipulation of several intrinsic and extrinsic factors has been proposed in order to stimulate axonal regeneration and functional repairing of axonal connections in the visual pathway. However, there is a missing point in the process since, until now, there is no therapeutic strategy directed to promote axonal regeneration of RGCs as a therapeutic approach for optic neuropathies.
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21
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Therapeutic Strategies for Attenuation of Retinal Ganglion Cell Injury in Optic Neuropathies: Concepts in Translational Research and Therapeutic Implications. BIOMED RESEARCH INTERNATIONAL 2019; 2019:8397521. [PMID: 31828134 PMCID: PMC6885158 DOI: 10.1155/2019/8397521] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 10/07/2019] [Accepted: 10/28/2019] [Indexed: 12/19/2022]
Abstract
Retinal ganglion cell (RGC) death is the central and irreversible endpoint of optic neuropathies. Current management of optic neuropathies and glaucoma focuses on intraocular pressure-lowering treatment which is insufficient. As such, patients are effectively condemned to irreversible visual impairment. This review summarizes experimental treatments targeting RGCs over the last decade. In particular, we examine the various treatment modalities and determine their viability and limitations in translation to clinical practice. Experimental RGC treatment can be divided into (1) cell replacement therapy, (2) neuroprotection, and (3) gene therapy. For cell replacement therapy, difficulties remain in successfully integrating transplanted RGCs from various sources into the complex neural network of the human retina. However, there is significant potential for achieving full visual restoration with this technique. Neuroprotective strategies, in the form of pharmacological agents, nutritional supplementation, and neurotrophic factors, are viable strategies with encouraging results from preliminary noncomparative interventional case series. It is important to note, however, that most published studies are focused on glaucoma, with few treating optic neuropathies of other etiologies. Gene therapy, through the use of viral vectors, has shown promising results in clinical trials, particularly for diseases with specific genetic mutations like Leber's hereditary optic neuropathy. This treatment technique can be further extended to nonhereditary diseases, through transfer of genes promoting cell survival and neuroprotection. Crucially though, for gene therapy, teratogenicity remains a significant issue in translation to clinical practice.
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22
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Zhou X, Zhang T, Wu J. Brimonidine enhances inhibitory postsynaptic activity of OFF- and ON-type retinal ganglion cells in a Wistar rat chronic glaucoma model. Exp Eye Res 2019; 189:107833. [PMID: 31618613 DOI: 10.1016/j.exer.2019.107833] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 06/07/2019] [Accepted: 10/09/2019] [Indexed: 10/25/2022]
Abstract
Glaucoma is a multifactorial disease in which retinal ganglion cells (RGCs) undergo excitotoxic damage, leading to their degeneration. The α2-adrenoceptor (α2-AR) agonist brimonidine exerts a neuroprotective effect by regulating postsynaptic excitatory N-methyl-D-aspartate (NMDA) receptor activity in RGCs. However, researchers have not clearly determined whether or how brimonidine regulates inhibitory synaptic transmission in rat models of chronic glaucoma. Whole-cell voltage-clamp and current-clamp recordings were performed in ON- and OFF-type RGCs in retinal slices. Brimonidine directly and acutely enhanced γ-aminobutyric acidergic (GABAergic) transmission mediated by ionotropic GABAA receptors in ON- and OFF-type RGCs in rat retinal slices; this effect occurred at the synaptic terminals and was independent of action potentials and multi-synaptic connections. The highly selective α2-AR antagonist yohimbine blocked the effects of brimonidine. Regarding the postsynaptic GABA receptor sensitivity, brimonidine also increased the amplitude of the GABA-induced current. Additionally, compared to RGCs from the control group, the frequencies and amplitudes of spontaneous excitatory postsynaptic currents (sEPSCs) and miniature excitatory postsynaptic currents (mEPSCs) did not change after brimonidine gravity perfusion. Brimonidine significantly decreased the spontaneous firing frequency of rat RGCs with intact synaptic inputs and decreased the resting membrane potential of RGCs, changes that were blocked by the highly selective GABAA receptor antagonist SR95531. SR95531 alone increased spontaneous action potentials and the resting membrane potential. Based on these findings, an α2-AR agonist facilitated the frequency of the GABAergic inhibitory postsynaptic currents (IPSCs), directly increased the amplitude of the postsynaptic GABA-induced current (GABA receptor reactivity/sensitivity), suppressed the firing frequency of spontaneous action in RGCs with intact synaptic inputs and decreased the resting membrane potential of RGCs, thus deactivating RGCs from the neural network level and reducing the excitotoxic damage occurring during the pathological process of chronic glaucoma.
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Affiliation(s)
- Xujiao Zhou
- Eye Institute, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, Shanghai, 200032, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, 200032, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences (Fudan University), Shanghai, 200032, China.
| | - Ting Zhang
- Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, 200032, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences (Fudan University), Shanghai, 200032, China; Research Center, Eye & ENT Hospital, Fudan University, Shanghai, 200032, China.
| | - Jihong Wu
- Eye Institute, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, Shanghai, 200032, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, 200032, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences (Fudan University), Shanghai, 200032, China; Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Fudan University, Shanghai, 200032, China.
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Khatib TZ, Martin KR. Neuroprotection in Glaucoma: Towards Clinical Trials and Precision Medicine. Curr Eye Res 2019; 45:327-338. [PMID: 31475591 DOI: 10.1080/02713683.2019.1663385] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Purpose: The eye is currently at the forefront of translational medicine and therapeutics. However, despite advances in technology, primary open-angle glaucoma remains the leading cause of irreversible blindness worldwide. Traditional intraocular pressure (IOP)-lowering therapies are often not sufficient to prevent progression to blindness, even in patients with access to high-quality healthcare. Neuroprotection strategies, which aim to boost the ability of target cells to withstand a pathological insult, have shown significant promise in animal models but none have shown clinically relevant efficacy in human clinical trials to date. We sought to evaluate the current status of neuroprotection clinical trials for glaucoma and identify limitations which have prevented translation of new glaucoma therapies to date.Methods: Literature searches identified English language references. Sources included MEDLINE, EMBASE, the Cochrane Library and Web of Science databases; reference lists of retrieved studies; and internet pages of relevant organisations, meetings and conference proceedings, and clinical trial registries.Results: We discuss six key neuroprotective strategies for glaucoma that have reached the clinical trial stage. Delivery of neurotrophic factors through gene therapy is also progressing towards glaucoma clinical trials. Refinements in trial design and the use of new modalities to define structural and functional endpoints may improve our assessment of disease activity and treatment efficacy. Advances in our understanding of compartmentalised glaucomatous degeneration and continued progress in the molecular profiling of glaucoma patients will enable us to predict individual risk and tailor treatment.Conclusion: New approaches to future glaucoma neuroprotection trials could improve the prospects for new glaucoma therapies. Glaucoma treatment tailored according to an individual's unique risk profile may become increasingly common in the future.
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Affiliation(s)
- Tasneem Z Khatib
- John Van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,Eye Department, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.,Medical Sciences Division, University of Oxford, Oxford, UK
| | - Keith R Martin
- John Van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,Eye Department, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.,Cambridge NIHR Biomedical Research Centre, Cambridge, UK.,Wellcome Trust - 5 MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK.,Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, Australia.,Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
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24
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Hayreh SS. Controversies on neuroprotection therapy in non-arteritic anterior ischaemic optic neuropathy. Br J Ophthalmol 2019; 104:153-156. [PMID: 31488431 DOI: 10.1136/bjophthalmol-2019-314656] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 08/14/2019] [Accepted: 08/20/2019] [Indexed: 12/24/2022]
Abstract
OBJECTIVE There has long been a great interest in neuroprotection therapy for ischaemic stroke and various types of optic neuropathies. In view of that, I reviewed the literature on the role of neuroprotection for non-arteritic anterior ischaemic optic neuropathy (NA-AION). METHODS The review is based on a PubMed search of literature about the use of neuroprotectors in stroke and optic neuropathies and about current clinical trials of RPh201 and QPI-1007 in NA-AION. RESULTS Several neuroprotection agents for ischaemic stroke and various types of optic neuropathies have been evaluated extensively in experimental studies in animals and benefits claimed. However, translation of therapeutic strategies for neuroprotection from experimental research to humans has invariably been fraught with failure. Two currently ongoing studies dealing with neuroprotection by RPh201 and QPI-1007 in NA-AION may have limitations in their rationale and study designs. CONCLUSIONS Unfortunately, in spite of all the experimental and clinical research on neuroprotection agents in NA-AION so far, we have no scientifically proven evidence of neuroprotection agents showing any benefit in the human clinical studies so far.
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Yap T, Shamsher E, Guo L, Cordeiro M. Ophthalmic Research Lecture 2018: DARC as a Potential Surrogate Marker. Ophthalmic Res 2019; 63:1-7. [DOI: 10.1159/000500527] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 11/19/2022]
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26
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Devoldere J, Wels M, Peynshaert K, Dewitte H, De Smedt SC, Remaut K. The obstacle course to the inner retina: Hyaluronic acid-coated lipoplexes cross the vitreous but fail to overcome the inner limiting membrane. Eur J Pharm Biopharm 2019; 141:161-171. [PMID: 31150809 DOI: 10.1016/j.ejpb.2019.05.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 05/27/2019] [Accepted: 05/27/2019] [Indexed: 10/26/2022]
Abstract
Considerable research over the last few years has revealed dysregulation of growth factors in various retinal diseases, such as glaucoma, diabetic retinopathy and photoreceptor degenerations. The use of messengerRNA (mRNA) to transiently overexpress a specific factor could compensate for this imbalance. However, a critical challenge of this approach lies in the ability to efficiently deliver mRNA molecules to the retinal target cells. In this study we found that intravitreal (IVT) injection is an attractive approach to deliver mRNA to the retina, providing two critical barriers can be overcome: the vitreous and the inner limiting membrane (ILM). We demonstrated that the vitreous is indeed a major hurdle in the delivery of the cationic mRNA-complexes to retinal cells, both in terms of vitreal mobility and cellular uptake. To improve their intravitreal mobility and avoid unwanted extracellular interactions, we evaluated the use of hyaluronic acid (HA) as an electrostatic coating strategy. This HA-coating provided the complexes with a negative surface charge, markedly enhancing their mobility in the vitreous humor, without reducing their cellular internalization and transfection efficiency. However, although this coating strategy allows the mRNA-complexes to successfully overcome the vitreal barrier, the majority of the particles accumulated at the ILM. This study therefore underscores the crucial barrier function of the ILM toward non-viral retinal gene delivery and the need to smartly design mRNA-carriers able to surmount the vitreous as well as the ILM.
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Affiliation(s)
- Joke Devoldere
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium
| | - Mike Wels
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium
| | - Karen Peynshaert
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium
| | - Heleen Dewitte
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium; Laboratory for Molecular and Cellular Therapy, Department of Biomedical Sciences, Medical School of the Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1050 Jette, Belgium; Cancer Research Institute Ghent (CRIG), Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Stefaan C De Smedt
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium; Cancer Research Institute Ghent (CRIG), Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Katrien Remaut
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium; Cancer Research Institute Ghent (CRIG), Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium.
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27
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Komáromy AM, Bras D, Esson DW, Fellman RL, Grozdanic SD, Kagemann L, Miller PE, Moroi SE, Plummer CE, Sapienza JS, Storey ES, Teixeira LB, Toris CB, Webb TR. The future of canine glaucoma therapy. Vet Ophthalmol 2019; 22:726-740. [PMID: 31106969 PMCID: PMC6744300 DOI: 10.1111/vop.12678] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 04/05/2019] [Accepted: 04/15/2019] [Indexed: 02/06/2023]
Abstract
Canine glaucoma is a group of disorders that are generally associated with increased intraocular pressure (IOP) resulting in a characteristic optic neuropathy. Glaucoma is a leading cause of irreversible vision loss in dogs and may be either primary or secondary. Despite the growing spectrum of medical and surgical therapies, there is no cure, and many affected dogs go blind. Often eyes are enucleated because of painfully high, uncontrollable IOP. While progressive vision loss due to primary glaucoma is considered preventable in some humans, this is mostly not true for dogs. There is an urgent need for more effective, affordable treatment options. Because newly developed glaucoma medications are emerging at a very slow rate and may not be effective in dogs, work toward improving surgical options may be the most rewarding approach in the near term. This Viewpoint Article summarizes the discussions and recommended research strategies of both a Think Tank and a Consortium focused on the development of more effective therapies for canine glaucoma; both were organized and funded by the American College of Veterinary Ophthalmologists Vision for Animals Foundation (ACVO-VAF). The recommendations consist of (a) better understanding of disease mechanisms, (b) early glaucoma diagnosis and disease staging, (c) optimization of IOP-lowering medical treatment, (d) new surgical therapies to control IOP, and (e) novel treatment strategies, such as gene and stem cell therapies, neuroprotection, and neuroregeneration. In order to address these needs, increases in research funding specifically focused on canine glaucoma are necessary.
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Affiliation(s)
- András M Komáromy
- College of Veterinary Medicine, Michigan State University, East Lansing, Michigan
| | - Dineli Bras
- Centro de Especialistas Veterinarios de Puerto Rico, San Juan, Puerto Rico
| | | | | | | | - Larry Kagemann
- U.S. Food and Drug Administration, Silver Spring, Maryland.,New York University School of Medicine, New York, New York.,Department of Ophthalmology, School of Medicine, University of Maryland, Baltimore, Maryland
| | - Paul E Miller
- School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin
| | - Sayoko E Moroi
- Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan
| | - Caryn E Plummer
- College of Veterinary Medicine, University of Florida, Gainesville, Florida
| | | | - Eric S Storey
- South Atlanta Veterinary Emergency & Specialty, Fayetteville, Georgia
| | - Leandro B Teixeira
- School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin
| | - Carol B Toris
- Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, Nebraska
| | - Terah R Webb
- MedVet Medical & Cancer Centers for Pets, Worthington, Ohio
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28
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Shah M, Cabrera-Ghayouri S, Christie LA, Held KS, Viswanath V. Translational Preclinical Pharmacologic Disease Models for Ophthalmic Drug Development. Pharm Res 2019; 36:58. [PMID: 30805711 PMCID: PMC6394514 DOI: 10.1007/s11095-019-2588-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 02/08/2019] [Indexed: 12/14/2022]
Abstract
Preclinical models of human diseases are critical to our understanding of disease etiology, pathology, and progression and enable the development of effective treatments. An ideal model of human disease should capture anatomical features and pathophysiological mechanisms, mimic the progression pattern, and should be amenable to evaluating translational endpoints and treatment approaches. Preclinical animal models have been developed for a variety of human ophthalmological diseases to mirror disease mechanisms, location of the affected region in the eye and severity. These models offer clues to aid in our fundamental understanding of disease pathogenesis and enable progression of new therapies to clinical development by providing an opportunity to gain proof of concept (POC). Here, we review preclinical animal models associated with development of new therapies for diseases of the ocular surface, glaucoma, presbyopia, and retinal diseases, including diabetic retinopathy and age-related macular degeneration (AMD). We have focused on summarizing the models critical to new drug development and described the translational features of the models that contributed to our understanding of disease pathogenesis and establishment of preclinical POC.
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Affiliation(s)
- Mihir Shah
- Biological Research, Allergan plc, 2525 Dupont Drive, Irvine, California, 92612, USA
| | - Sara Cabrera-Ghayouri
- Biological Research, Allergan plc, 2525 Dupont Drive, Irvine, California, 92612, USA
| | - Lori-Ann Christie
- Biological Research, Allergan plc, 2525 Dupont Drive, Irvine, California, 92612, USA
| | - Katherine S Held
- Biological Research, Allergan plc, 2525 Dupont Drive, Irvine, California, 92612, USA
| | - Veena Viswanath
- Biological Research, Allergan plc, 2525 Dupont Drive, Irvine, California, 92612, USA.
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29
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Takeda A, Shinozaki Y, Kashiwagi K, Ohno N, Eto K, Wake H, Nabekura J, Koizumi S. Microglia mediate non-cell-autonomous cell death of retinal ganglion cells. Glia 2018; 66:2366-2384. [PMID: 30375063 DOI: 10.1002/glia.23475] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 05/23/2018] [Accepted: 05/28/2018] [Indexed: 12/22/2022]
Abstract
Excitotoxicity is well known in the neuronal death in the brain and is also linked to neuronal damages in the retina. Recent accumulating evidence show that microglia greatly affect excitotoxicity in the brain, but their roles in retina have received only limited attention. Here, we report that retinal excitotoxicity is mediated by microglia. To this end, we employed three discrete methods, that is, pharmacological inhibition of microglia by minocycline, pharmacological ablation by an antagonist for colony stimulating factor 1 receptor (PLX5622), and genetic ablation of microglia using Iba1-tTA::DTAtetO/tetO mice. Intravitreal injection of NMDA increased the number of apoptotic retinal ganglion cells (RGCs) followed by reduction in the number of RGCs. Although microglia did not respond to NMDA directly, they became reactive earlier than RGC damages. Inhibition or ablation of microglia protected RGCs against NMDA. We found up-regulation of proinflammatory cytokine genes including Il1b, Il6 and Tnfa, among which Tnfa was selectively blocked by minocycline. PLX5622 also suppressed Tnfa expression. Tumor necrosis factor α (TNFα) signals were restricted in microglia at very early followed by spreading into other cell types. TNFα up-regulation in microglia and other cells were significantly attenuated by minocycline and PLX5622, suggesting a central role of microglia for TNFα induction. Both inhibition of TNFα and knockdown of TNF receptor type 1 by siRNA protected RGCs against NMDA. Taken together, our data demonstrate that a phenotypic change of microglia into a neurotoxic one is a critical event for the NMDA-induced degeneration of RGCs, suggesting an importance of non-cell-autonomous mechanism in the retinal neuronal excitotoxicity.
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Affiliation(s)
- Akiko Takeda
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Youichi Shinozaki
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Kenji Kashiwagi
- Department of Ophthalmology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Nobuhiko Ohno
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences (NIPS), Aichi, Japan.,Department of Anatomy, Jichi Medical University, Tochigi, Japan
| | - Kei Eto
- Division of Homeostatic Development, NIPS, Aichi, Japan
| | - Hiroaki Wake
- Division of Homeostatic Development, NIPS, Aichi, Japan.,Division of System Neuroscience, Graduate School of Medicine, Kobe University, Hyogo, Japan.,Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Saitama, Japan
| | | | - Schuichi Koizumi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
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30
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Adeghate J, Rahmatnejad K, Waisbourd M, Katz LJ. Intraocular pressure-independent management of normal tension glaucoma. Surv Ophthalmol 2018; 64:101-110. [PMID: 30300625 DOI: 10.1016/j.survophthal.2018.08.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 08/15/2018] [Accepted: 08/20/2018] [Indexed: 11/19/2022]
Affiliation(s)
- Jennifer Adeghate
- Wills Eye Hospital, Glaucoma Research Department, Philadelphia, Pennsylvania, USA; Weill Cornell Medical College, Department of Ophthalmology, New York, New York, USA
| | - Kamran Rahmatnejad
- Wills Eye Hospital, Glaucoma Research Department, Philadelphia, Pennsylvania, USA
| | - Michael Waisbourd
- Wills Eye Hospital, Glaucoma Research Department, Philadelphia, Pennsylvania, USA; Thomas Jefferson University, Department of Ophthalmology, Philadelphia, Pennsylvania, USA; Tel-Aviv University Medical Center, Glaucoma Research Center, Tel-Aviv, Israel
| | - L Jay Katz
- Wills Eye Hospital, Glaucoma Research Department, Philadelphia, Pennsylvania, USA; Thomas Jefferson University, Department of Ophthalmology, Philadelphia, Pennsylvania, USA.
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31
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Sakamoto K, Mori A, Ishii K, Nakahara T. [Selective neuronal cell death in retinal degenerative diseases]. Nihon Yakurigaku Zasshi 2018; 152:58-63. [PMID: 30101861 DOI: 10.1254/fpj.152.58] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Retinal degenerative diseases, such as glaucoma and retinitis pigmentosa (RP), are the leading causes of blindness in adults. In Japan, glaucoma is a leading cause, and RP is third major cause of acquired blindness. Specific types of neurons are injured in the patients of glaucoma and RP. Retinal ganglion cells (RGC) are specifically degenerated in glaucoma. Excitotoxicity caused by excess glutamate in the retinal extracellular space is thought to be one of the mechanisms of RGC death induced by glaucoma and retinal central artery occlusion. Retinal ischemia-reperfusion, intravitreal NMDA injection, intravitreal NO donor injection and knock out of glutamate aspartate transporter, which are used as the experimental models of glaucoma, are known to induce RGC death. RGCs are vulnerable for excess glutamate and oxidative stress related to NO, and this vulnerability may be involved in pathogenesis of glaucomatous optic neuropathy. RP, which is characterized by progressive photoreceptor-selective degeneration, is caused by mutation of the genes related to the function of photoreceptor and retinal pigment epithelium. It has not been thoroughly clarified how the mutations induce specific photoreceptor death. Tunicamycin is widely known to induce ER stress, and intravitreal tunicamycin cause photoreceptor-specific degeneration. Therefore, ER stress may cause photoreceptor-selective degeneration in RP.
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Affiliation(s)
- Kenji Sakamoto
- Department of Molecular Pharmacology, Kitasato University School of Pharmaceutical Sciences
| | - Asami Mori
- Department of Molecular Pharmacology, Kitasato University School of Pharmaceutical Sciences
| | - Kunio Ishii
- Department of Molecular Pharmacology, Kitasato University School of Pharmaceutical Sciences.,Pharmaceutical Education Center, Yokohama University of Pharmacy
| | - Tsutomu Nakahara
- Department of Molecular Pharmacology, Kitasato University School of Pharmaceutical Sciences
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32
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Weinreb RN, Liebmann JM, Cioffi GA, Goldberg I, Brandt JD, Johnson CA, Zangwill LM, Schneider S, Badger H, Bejanian M. Oral Memantine for the Treatment of Glaucoma: Design and Results of 2 Randomized, Placebo-Controlled, Phase 3 Studies. Ophthalmology 2018; 125:1874-1885. [PMID: 30082073 DOI: 10.1016/j.ophtha.2018.06.017] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 05/16/2018] [Accepted: 06/12/2018] [Indexed: 10/28/2022] Open
Abstract
PURPOSE To evaluate the effectiveness and safety of oral memantine as a potential neuroprotective agent in open-angle glaucoma (OAG) at risk for progression. DESIGN Two randomized, double-masked, placebo-controlled, parallel-group, multicenter, 48-month studies identically designed, initiated 1 year apart, and completed in 2006. Protocol amendments included a 1-year extension (first study) and change in primary endpoint and analysis (second study). PARTICIPANTS Patients (2298 total) with bilateral OAG; glaucomatous optic disc damage and visual field loss in 1 eye; glaucomatous optic disc damage and/or visual field loss in the contralateral eye (at screening), topically treated or untreated intraocular pressure (IOP) of 21 mmHg or less (at baseline); and at risk of glaucomatous progression (per prespecified criteria). METHODS Patients were randomized 3:2:2 to receive memantine 20 mg, memantine 10 mg, or placebo tablets daily. Glaucomatous progression was assessed in the intent-to-treat population by full-threshold standard automated perimetry (SAP), frequency doubling technology (FDT), and stereoscopic optic disc photographs, standardized by quality control assessment at centralized reading centers. Safety evaluations included adverse events (AEs), best-corrected visual acuity, biomicroscopy, IOP, and ophthalmoscopy. Efficacy data from each study were analyzed per protocol. Pooled analyses of efficacy and safety data were also performed. MAIN OUTCOME MEASURES The predefined primary efficacy measure was glaucomatous visual field progression, as measured by SAP. Additional efficacy measures included glaucomatous progression of visual field (FDT) and optic nerve damage (stereoscopic optic disc photographs). RESULTS The proportion of patients who completed the studies was similar among groups (80%-83%). Compared with placebo, daily treatment with memantine 10 mg or 20 mg for 48 months did not delay glaucomatous progression significantly in the individual studies and pooled analyses. The pooled risk reduction ratio (95% confidence interval) assessed by SAP was -0.13 (-0.40, 0.09) and -0.17 (-0.46, 0.07) for memantine 10 mg and 20 mg, respectively. Results were similar per FDT and stereoscopic optic disc photographs. The most common AEs leading to treatment discontinuations were dizziness, headache, fatigue, and nausea. CONCLUSIONS With technologies available when the studies were conducted, daily treatment with memantine over 48 months was not shown to prevent glaucomatous progression in this patient population.
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Affiliation(s)
- Robert N Weinreb
- Hamilton Glaucoma Center, Shiley Eye Institute and Department of Ophthalmology, University of California San Diego, La Jolla, California.
| | - Jeffrey M Liebmann
- Edward S. Harkness Eye Institute, Columbia University Medical Center, New York, New York
| | - George A Cioffi
- Edward S. Harkness Eye Institute, Columbia University Medical Center, New York, New York
| | - Ivan Goldberg
- Discipline of Ophthalmology, University of Sydney and Sydney Eye Hospital, Sydney, Australia
| | - James D Brandt
- UC Davis Eye Center, University of California, Davis, Sacramento, California
| | - Chris A Johnson
- Department of Ophthalmology, University of Iowa, Iowa City, Iowa
| | - Linda M Zangwill
- Hamilton Glaucoma Center, Shiley Eye Institute and Department of Ophthalmology, University of California San Diego, La Jolla, California
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Wubben TJ, Besirli CG, Johnson MW, Zacks DN. Retinal Neuroprotection: Overcoming the Translational Roadblocks. Am J Ophthalmol 2018; 192:xv-xxii. [PMID: 29702074 DOI: 10.1016/j.ajo.2018.04.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 04/13/2018] [Accepted: 04/13/2018] [Indexed: 11/25/2022]
Abstract
PURPOSE To elucidate the issues that have prevented successful translation of neuroprotective therapeutic modalities for retinal disease from the preclinical to the clinical realm and to suggest strategies to circumvent these barriers in order to develop novel treatments to prevent vision loss. DESIGN Interpretive essay. METHODS Review and synthesis of selected reports of neuroprotective approaches for retinal disease, with interpretation and perspective. RESULTS Retinal neuroprotection is defined as any measure that reduces the death of retinal cells or axonal extensions into the optic nerve, and there is a great unmet need for such therapeutic modalities. Despite encouraging preclinical data, the translation of neuroprotective therapies to the clinic has been fraught with failure. Fundamental issues that have plagued this transition include the animal models used in preclinical studies, the reproducibility of the preclinical data, and the choice of meaningful clinical trial endpoints. Developing animal models that more aptly mimic human disease, defining a set of guidelines for preclinical evaluation of neuroprotective therapies in retinal disease, and identifying and validating biomarkers as surrogate clinical endpoints that shorten and optimize drug development timelines may circumvent some of these barriers to translation. CONCLUSIONS Neuroprotective therapeutic approaches have the potential to prevent vision loss in millions of people affected with eye diseases worldwide. However, a stigma currently accompanies the concept of neuroprotection because of the many past failures to bridge the gap between the preclinical and clinical realms. Understanding and addressing the fundamental reasons for the failure of translatable research provides hope for the future development of neuroprotective therapies.
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Mahalingam K, Chaurasia AK, Gowtham L, Gupta S, Somarajan BI, Velpandian T, Sihota R, Gupta V. Therapeutic potential of valproic acid in advanced glaucoma: A pilot study. Indian J Ophthalmol 2018; 66:1104-1108. [PMID: 30038151 PMCID: PMC6080453 DOI: 10.4103/ijo.ijo_108_18] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Accepted: 04/23/2018] [Indexed: 11/12/2022] Open
Abstract
Purpose Oral valproic acid (VPA) used as an anticonvulsant has been shown to improve contrast threshold sensitivities in patients receiving it on long-term. This study aimed to evaluate the efficacy of oral VPA in improving visual function in eyes with advanced stage glaucoma. Methods In this prospective randomized study, 31 patients (n = 31 eyes) with advanced stage glaucoma (with an intraocular pressure <16 mmHg) in at least one eye received oral VPA 500 mg once a day for 3 months and 33 patients (n = 33 eyes) continued on glaucoma therapy. Patients were followed up at 3 and 12 months (to evaluate the legacy effect of the drug). Blood VPA concentrations were measured at 3 months. Following parameters were assessed at baseline, 3 months and 12 months: log of the minimum angle of resolution (LogMAR) visual acuity, mean deviation on visual fields, and multifocal electroretinogram (ERG). Results Median LogMar visual acuity in the VPA group improved from 0.3 at baseline to 0.18 and 0.18 at 3 and 12 months, respectively (P < 0.01). In comparison, the median visual acuity in control group at baseline was 0.18 and showed neither worsening nor improvement over 3 and 12 months (P = 0.56). The improvement in VPA group was significant compared to the control group (P < 0.01; Wilcoxon Signed-rank test). An improvement in one line was experienced in 11 out of 31 eyes in the VPA group compared to 1 out of 33 eyes among controls (P = 0.003). No significant improvement was noted in the mean deviation, and the multifocal ERG (Latency and amplitudes) in the VPA-treated patients. The average blood VPA concentration measured at 3 months of therapy was 26 ± 8.9 μg/ml (range 8-55 μg/ml) which is much lower than that achieved during anticonvulsant therapy. None of the patients complained of any adverse effects that required stopping VPA therapy. Conclusion A 3 months oral VPA therapy results in some improvement in visual acuity in a subgroup of eyes with advanced glaucoma and the effect was seen to persist 9 months after the drug was stopped.
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Affiliation(s)
- Karthikeyan Mahalingam
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Abadh Kumar Chaurasia
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | | | - Shikha Gupta
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Bindu I Somarajan
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Thirumurthy Velpandian
- Department of Ocular Pharmacology, All India Institute of Medical Sciences, New Delhi, India
| | - Ramanjit Sihota
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Viney Gupta
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
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Abstract
Glaucoma is one of the leading causes of irreversible visual loss, which has been estimated to affect 3.5% of those over 40 years old and projected to affect a total of 112 million people by 2040. Such a dramatic increase in affected patients demonstrates the need for continual improvement in the way we diagnose and treat this condition. Annexin A5 is a 36 kDa protein that is ubiquitously expressed in humans and is studied as an indicator of apoptosis in several fields. This molecule has a high calcium-dependent affinity for phosphatidylserine, a cell membrane phospholipid externalized to the outer cell membrane in early apoptosis. The DARC (Detection of Apoptosing Retinal Cells) project uses fluorescently-labelled annexin A5 to assess glaucomatous degeneration, the inherent process of which is the apoptosis of retinal ganglion cells. Furthermore, this project has conducted investigation of the retinal apoptosis in the neurodegenerative conditions of the eye and brain. In this present study, we summarized the use of annexin A5 as a marker of apoptosis in the eye. We also relayed the progress of the DARC project, developing real-time imaging of retinal ganglion cell apoptosis in vivo from the experimental models of disease and identifying mechanisms underlying neurodegeneration and its treatments, which has been applied to the first human clinical trials. DARC has potential as a biomarker in neurodegeneration, especially in the research of novel treatments, and could be a useful tool for the diagnosis and monitoring of glaucoma.
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36
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Affiliation(s)
- Mohammadali Almasieh
- Departments of Ophthalmology and Neurology, McGill University, Montreal H4A 3S5, Canada
- Maisonneuve-Rosemont Hospital Research Center and Department of Ophthalmology, University of Montreal, Montreal H1T 2M4, Canada
| | - Leonard A. Levin
- Departments of Ophthalmology and Neurology, McGill University, Montreal H4A 3S5, Canada
- Maisonneuve-Rosemont Hospital Research Center and Department of Ophthalmology, University of Montreal, Montreal H1T 2M4, Canada
- Department of Ophthalmology and Visual Science, University of Wisconsin, Madison, Wisconsin 53706
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European Glaucoma Society Terminology and Guidelines for Glaucoma, 4th Edition - Chapter 3: Treatment principles and options Supported by the EGS Foundation: Part 1: Foreword; Introduction; Glossary; Chapter 3 Treatment principles and options. Br J Ophthalmol 2017; 101:130-195. [PMID: 28559477 PMCID: PMC5583689 DOI: 10.1136/bjophthalmol-2016-egsguideline.003] [Citation(s) in RCA: 179] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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38
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Protecting retinal ganglion cells. Eye (Lond) 2017; 31:218-224. [PMID: 28085136 DOI: 10.1038/eye.2016.299] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 11/26/2016] [Indexed: 01/08/2023] Open
Abstract
Retinal ganglion cell degeneration underlies several conditions which give rise to significant visual compromise, including glaucoma, hereditary optic neuropathies, ischaemic optic neuropathies, and demyelinating disease. In this review, we discuss the emerging strategies for neuroprotection specifically in the context of glaucoma, including pharmacological neuroprotection, mesenchymal stem cells, and gene therapy approaches. We highlight potential pitfalls that need to be considered when developing these strategies and outline future directions, including the prospects for clinical trials.
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Abstract
Glaucoma is both the most common optic neuropathy worldwide and the most common cause of irreversible blindness in the world. The only proven treatment for glaucomatous optic neuropathy is lowering the intraocular pressure, achieved with a variety of pharmacological, laser, and surgical approaches. Over the past 2 decades there has been much basic and clinical research into achieving treatment of the underlying optic nerve damage with neuroprotective approaches. However, none has resulted in regulatory approval based on successful phase 3 studies. This chapter discusses the reasons for this "lost in translation" aspect of glaucoma neuroprotection, and outlines issues at the laboratory and clinical trial level that need to be addressed for successful development of neuroprotective therapies.
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Affiliation(s)
- Leonard A Levin
- Department of Ophthalmology, McGill University, Montreal, QC, Canada
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
- McGill Academic Eye Centre, 5252 de Maisonneuve West, Suite 400, Montreal, QC, Canada, H4A 3S5
- Department of Ophthalmology, University of Montreal, Montreal, QC, Canada
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40
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Ortiz G, Odom JV, Passaglia CL, Tzekov RT. Efferent influences on the bioelectrical activity of the retina in primates. Doc Ophthalmol 2016; 134:57-73. [PMID: 28032236 DOI: 10.1007/s10633-016-9567-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 12/13/2016] [Indexed: 11/28/2022]
Abstract
PURPOSE The existence of retinopetal (sometimes referred to as "efferent" or "centrifugal") axons in the mammalian optic nerve is a topic of long-standing debate. Opposition is fading as efferent innervation of the retina has now been widely documented in rodents and other animals. The existence and function of an efferent system in humans and non-human primates has not, though, been definitively established. Such a feedback pathway could have important functional, clinical, and experimental significance to the field of vision science and ophthalmology. METHODS Following a comprehensive literature review (PubMed and Google Scholar, until July 2016), we present evidence regarding a system that can influence the bioelectrical activity of the retina in primates. RESULTS Anatomical and physiological evidences are presented separately. Improvements in histological staining and the advent of retrograde nerve fiber tracers have allowed for more confidence in the identification of efferent optic nerve fibers, including back to their point of origin. CONCLUSION Even with the accumulation of more modern anatomical and physiological evidence, some limitations and uncertainties about crucial details regarding the origins and role of a top-down, efferent system still exist. However, the summary of the evidence from earlier and more modern studies makes a compelling case in support of such a system in humans and non-human primates.
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Affiliation(s)
- Gonzalo Ortiz
- Department of Ophthalmology, University of South Florida, 12901 Bruce B. Downs Blvd., MDC 21, Tampa, FL, 33612, USA
| | - J Vernon Odom
- Department of Ophthalmology, West Virginia University, Morgantown, WV, USA
| | - Christopher L Passaglia
- Department of Ophthalmology, University of South Florida, 12901 Bruce B. Downs Blvd., MDC 21, Tampa, FL, 33612, USA.,Department of Chemical and Biomedical Engineering, University of South Florida, Tampa, FL, USA
| | - Radouil T Tzekov
- Department of Ophthalmology, University of South Florida, 12901 Bruce B. Downs Blvd., MDC 21, Tampa, FL, 33612, USA. .,The Roskamp Institute, Sarasota, FL, USA.
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41
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Weinreb RN, Leung CKS, Crowston JG, Medeiros FA, Friedman DS, Wiggs JL, Martin KR. Primary open-angle glaucoma. Nat Rev Dis Primers 2016; 2:16067. [PMID: 27654570 DOI: 10.1038/nrdp.2016.67] [Citation(s) in RCA: 269] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Glaucoma is an optic neuropathy that is characterized by the progressive degeneration of the optic nerve, leading to visual impairment. Glaucoma is the main cause of irreversible blindness worldwide, but typically remains asymptomatic until very severe. Open-angle glaucoma comprises the majority of cases in the United States and western Europe, of which, primary open-angle glaucoma (POAG) is the most common type. By contrast, in China and other Asian countries, angle-closure glaucoma is highly prevalent. These two types of glaucoma are characterized based on the anatomic configuration of the aqueous humour outflow pathway. The pathophysiology of POAG is not well understood, but it is an optic neuropathy that is thought to be associated with intraocular pressure (IOP)-related damage to the optic nerve head and resultant loss of retinal ganglion cells (RGCs). POAG is generally diagnosed during routine eye examination, which includes fundoscopic evaluation and visual field assessment (using perimetry). An increase in IOP, measured by tonometry, is not essential for diagnosis. Management of POAG includes topical drug therapies and surgery to reduce IOP, although new therapies targeting neuroprotection of RGCs and axonal regeneration are under development.
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Affiliation(s)
- Robert N Weinreb
- Shiley Eye Institute, Hamilton Glaucoma Center, Department of Ophthalmology, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA
| | - Christopher K S Leung
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Jonathan G Crowston
- Department of Ophthalmology, Centre for Eye Research Australia, University of Melbourne, Melbourne, Victoria, Australia
| | - Felipe A Medeiros
- Shiley Eye Institute, Hamilton Glaucoma Center, Department of Ophthalmology, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA
| | - David S Friedman
- Dana Center for Preventive Ophthalmology, Johns Hopkins Wilmer Eye Institute, Baltimore, Maryland, USA
| | - Janey L Wiggs
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts, USA
| | - Keith R Martin
- Department of Ophthalmology and Cambridge NIHR Biomedical Research Centre, University of Cambridge, Cambridge, UK
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Nucci C, Russo R, Martucci A, Giannini C, Garaci F, Floris R, Bagetta G, Morrone LA. New strategies for neuroprotection in glaucoma, a disease that affects the central nervous system. Eur J Pharmacol 2016; 787:119-26. [DOI: 10.1016/j.ejphar.2016.04.030] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 03/23/2016] [Accepted: 04/14/2016] [Indexed: 01/30/2023]
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Celiker H, Yuksel N, Solakoglu S, Karabas L, Aktar F, Caglar Y. Neuroprotective Effects of Memantine in the Retina of Glaucomatous Rats: An Electron Microscopic Study. J Ophthalmic Vis Res 2016; 11:174-82. [PMID: 27413498 PMCID: PMC4926565 DOI: 10.4103/2008-322x.183934] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Purpose: In this experimental study, the effects of systemic memantine administration on the retinal ultrastructure of experimentally induced glaucomatous rats were investigated. Methods: Twenty-four Wistar albino rats were included in this study. Glaucoma was induced by injecting sodium hyaluronate into the anterior chamber of the rats for a period of three weeks. As a control, 8 rats were sham treated (Group C). Glaucoma induced animals were divided into two groups; Group M (n = 8) received a single daily dose of 10 mg/kg memantine, and Group G received the same volume of saline (n = 8), via intraperitoneal route for a period of six weeks, starting with the induction of glaucoma. Then, all rats were sacrificed and the retinas were prepared for electron microscopic examination. Electron microscopic damage findings were graded between 0 and 4 and mean damage scores for each cell or layer was calculated for each group. Statistical comparison was made between group G and group M. Results: Including the photoreceptor cells, marked ultrastructural changes were observed in the retinas of the animals in group G. The ultrastructural changes in group M were modest and there was no significant cell death. Statistical findings indicated these results. Conclusion: Results of the present study suggest that memantine treatment, when started in the early phase of glaucomatous process, may help to preserve the retinal ultrastructure and thus prevent neuronal injury in experimentally induced glaucoma.
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Affiliation(s)
- Hande Celiker
- Department of Ophthalmology, School of Medicine, Marmara University, Istanbul, Turkey
| | - Nursen Yuksel
- Department of Ophthalmology, School of Medicine, Kocaeli University, Kocaeli, Turkey
| | - Seyhun Solakoglu
- Department of Histology and Embryology, School of Medicine, Istanbul University, Istanbul, Turkey
| | - Levent Karabas
- Department of Ophthalmology, School of Medicine, Kocaeli University, Kocaeli, Turkey
| | - Fadime Aktar
- Department of Histology and Embryology, School of Medicine, Istanbul University, Istanbul, Turkey
| | - Yusuf Caglar
- Department of Ophthalmology, School of Medicine, Kocaeli University, Kocaeli, Turkey
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Doozandeh A, Yazdani S. Neuroprotection in Glaucoma. J Ophthalmic Vis Res 2016; 11:209-20. [PMID: 27413504 PMCID: PMC4926571 DOI: 10.4103/2008-322x.183923] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Accepted: 08/03/2015] [Indexed: 11/04/2022] Open
Abstract
Glaucoma is a degenerative optic neuropathy characterized by retinal ganglion cell (RGC) loss and visual field defects. It is known that in some glaucoma patients, death of RGCs continues despite intraocular pressure (IOP) reduction. Neuroprotection in the field of glaucoma is defined as any treatment, independent of IOP reduction, which prevents RGC death. Glutamate antagonists, ginkgo biloba extract, neurotrophic factors, antioxidants, calcium channel blockers, brimonidine, glaucoma medications with blood regulatory effect and nitric oxide synthase inhibitors are among compounds with possible neuroprotective activity in preclinical studies. A few agents (such as brimonidine or memantine) with neuroprotective effects in experimental studies have advanced to clinical trials; however the results of clinical trials for these agents have not been conclusive. Nevertheless, lack of compelling clinical evidence has not prevented the off-label use of some of these compounds in glaucoma practice. Stem cell transplantation has been reported to halt experimental neurodegenerative disease processes in the absence of cell replacement. It has been hypothesized that transplantation of some types of stem cells activates multiple neuroprotective pathways via secretion of various factors. The advantage of this approach is a prolonged and targeted effect. Important concerns in this field include the secretion of unwanted harmful mediators, graft survival issues and tumorigenesis. Neuroprotection in glaucoma, pharmacologically or by stem cell transplantation, is an interesting subject waiting for broad and multidisciplinary collaborative studies to better clarify its role in clinical practice.
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Affiliation(s)
- Azadeh Doozandeh
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Shahin Yazdani
- Ocular Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Moreno Páramo D, Reyna Vielma S, Rodríguez Reyes A, Hernández Ayuso I, Quiroz Mercado H. Intravitreal memantine retinal toxicity in rabbits. ACTA ACUST UNITED AC 2015; 91:65-8. [PMID: 26652730 DOI: 10.1016/j.oftal.2015.10.005] [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: 06/11/2014] [Revised: 06/25/2015] [Accepted: 10/18/2015] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To histologically evaluate whether the intravitreal application of memantine produces retinal toxicity in rabbits. METHODS A cross-sectional design, experimental, descriptive study was performed on 16 eyes of 16 New Zealand rabbits of 3 kg, divided in 4 groups of 4 rabbits. A dose of 70 ng/ml of intravitreal memantine was administered in Group A, a dose of 150 ng/ml in Group B, a dose of 400 ng/ml in Group C, and Group D received 1 ml of balanced salt solution. The injected eye of half of each group was enucleated 15 days after the injection, and the rest within 30 days after injection. Following enucleation, each eye was placed in 10% formaldehyde. Histopathological analysis was performed on all enucleated eyes. The animals were treated according to the guidelines of the Association for Research on Vision and Ophthalmology (ARVO). RESULTS Groups A, B and D did not show any histopathological changes after their enucleation at 15 and 30 days. Group C showed changes in the photoreceptor layer after enucleation at 15 and 30 days. CONCLUSIONS In our study, it was observed that memantine concentrations at 70 ng/ml and 150 ng/ml are safe when administered intravitreally; however, doses of 400 ng/ml produced retinal structural changes. This research should continue to assess its clinical usefulness.
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Affiliation(s)
- D Moreno Páramo
- Servicio de Retina, Hospital General de México, México, D.F., México
| | - S Reyna Vielma
- Servicio de Retina, Hospital General de México, México, D.F., México.
| | - A Rodríguez Reyes
- Servicio de Patología, Asociación para Evitar la Ceguera en México, México, D.F., México
| | - I Hernández Ayuso
- Servicio de Patología, Asociación para Evitar la Ceguera en México, México, D.F., México
| | - H Quiroz Mercado
- Department of Ophthalmology, University of Colorado Denver, Denver, Colorado, EE. UU
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Yucel YH, Gupta N. A framework to explore the visual brain in glaucoma with lessons from models and man. Exp Eye Res 2015; 141:171-8. [DOI: 10.1016/j.exer.2015.07.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 06/29/2015] [Accepted: 07/09/2015] [Indexed: 01/13/2023]
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Abstract
Glaucoma is a progressive optic neuropathy that causes characteristic changes of the optic nerve and visual field in relation to intraocular pressure (IOP). It is now known that glaucoma can occur at statistically normal IOPs and prevalence studies have shown that normal tension glaucoma (NTG) is more common than previously thought. While IOP is believed to be the predominant risk factor in primary open angle glaucoma (POAG), IOP-independent risk factors, such as vascular dysregulation, are believed to play an important part in the pathogenesis of NTG. Though certain distinguishing phenotypic features of NTG have been reported, such as an increased frequency of disc hemorrhages, acquired pits of the optic nerve and characteristic patterns of disc cupping and visual field loss, there is much overlap of the clinical findings in NTG with POAG, suggesting that NTG is likely part of a continuum of open angle glaucomas. However, IOP modification is still the mainstay of treatment in NTG. As in traditional POAG, reduction of IOP can be achieved with the use of medications, laser trabeculoplasty or surgery. Studies now show that the choice of medication may also be important in determining the outcomes of these patients. Though it is likely that future treatment of NTG will involve modification of both IOP and IOP-independent risk factors, current efforts to develop IOP-independent neuroprotective treatments have not yet proven to be effective in humans.
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Affiliation(s)
| | - Joseph Caprioli
- Jules Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, USA
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Jung KI, Kim JH, Park CK. α2-Adrenergic modulation of the glutamate receptor and transporter function in a chronic ocular hypertension model. Eur J Pharmacol 2015; 765:274-83. [PMID: 26300392 DOI: 10.1016/j.ejphar.2015.08.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Revised: 08/19/2015] [Accepted: 08/19/2015] [Indexed: 12/13/2022]
Abstract
Excitotoxicity, glutamate-induced toxic effects to retinal ganglion cells (RGCs), is one of several mechanisms of RGC loss suggested in glaucoma. In this study, we focused on the role of glutamate transporter of glial cells as well as N-methyl-d-aspartate (NMDA) receptor with regard to glutamate toxicity in glaucoma. We also investigated whether α2-adrenoceptor activation could modulate glutamate transporters and NMDA receptors in a chronic ocular hypertension model. Brimonidine 0.15% was administered topically to the eyes of experimental glaucoma and control animals twice daily. After 8 weeks of intraocular pressure (IOP) elevation, staining with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) revealed an increase in the ganglion cell layer, and the number of TUNEL-positive cells was reduced by brimonidine treatment (P<0.05). Animals with experimentally induced glaucoma exhibited an increase in retinal stress marker glial fibrillary acidic protein (GFAP) immunoreactivity; brimonidine treatment reduced GFAP. Excitatory amino acid transporter 1(EAAT1) expression remained stable throughout the period of chronic ocular hypertension. α2-Adrenergic treatment upregulated EAAT1 protein levels (P<0.05). NMDA receptor (GluN1) expression was stimulated by chronic elevation of IOP, and GluN1-positive cells in ganglion cell layer were co-localized with TUNEL staining. Brimonidine administration suppressed GluN1 levels (P<0.05). These results indicate that brimonidine decreased RGC apoptosis, upregulating EAAT1 and downregulating NMDA receptors. We suggest that topical brimonidine treatment may decrease the glutamate excitotoxicity through modulation of glutamate transporter and NMDA receptor in glaucoma.
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Affiliation(s)
- Kyoung In Jung
- Department of Ophthalmology and Visual Science, Seoul St. Mary's Hospital, College of MedicineThe Catholic University of Korea, Seoul, Korea
| | - Jie Hyun Kim
- Department of Ophthalmology and Visual Science, Seoul St. Mary's Hospital, College of MedicineThe Catholic University of Korea, Seoul, Korea
| | - Chan Kee Park
- Department of Ophthalmology and Visual Science, Seoul St. Mary's Hospital, College of MedicineThe Catholic University of Korea, Seoul, Korea.
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49
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The non-human primate experimental glaucoma model. Exp Eye Res 2015; 141:57-73. [PMID: 26070984 DOI: 10.1016/j.exer.2015.06.005] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 06/03/2015] [Accepted: 06/06/2015] [Indexed: 01/05/2023]
Abstract
The purpose of this report is to summarize the current strengths and weaknesses of the non-human primate (NHP) experimental glaucoma (EG) model through sections devoted to its history, methods, important findings, alternative optic neuropathy models and future directions. NHP EG has become well established for studying human glaucoma in part because the NHP optic nerve head (ONH) shares a close anatomic association with the human ONH and because it provides the only means of systematically studying the very earliest visual system responses to chronic intraocular pressure (IOP) elevation, i.e. the conversion from ocular hypertension to glaucomatous damage. However, NHPs are impractical for studies that require large animal numbers, demonstrate spontaneous glaucoma only rarely, do not currently provide a model of the neuropathy at normal levels of IOP, and cannot easily be genetically manipulated, except through tissue-specific, viral vectors. The goal of this summary is to direct NHP EG and non-NHP EG investigators to the previous, current and future accomplishment of clinically relevant knowledge in this model.
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M K. Present and New Treatment Strategies in the Management of Glaucoma. Open Ophthalmol J 2015; 9:89-100. [PMID: 26069521 PMCID: PMC4460216 DOI: 10.2174/1874364101509010089] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Revised: 03/30/2015] [Accepted: 03/30/2015] [Indexed: 12/17/2022] Open
Abstract
Glaucoma is a neurodegenerative disease characterized by retinal ganglion cell (RGC) death and axonal loss. It remains a major cause of blindness worldwide. All current modalities of treatment are focused on lowering intraocular pressure (IOP), and it is evident that increased IOP is an important risk factor for progression of the disease. However, it is clear that a significant number of glaucoma patients show disease progression despite of pressure lowering treatments. Much attention has been given to the development of neuroprotective treatment strategies, but the identification of such has been hampered by lack of understanding of the etiology of glaucoma. Hence, in spite of many attempts no neuroprotective drug has yet been clinically approved. Even though neuroprotection is without doubt an important treatment strategy, many glaucoma subjects are diagnosed after substantial loss of RGCs. In this matter, recent approaches aim to rescue RGCs and regenerate axons in order to restore visual function in glaucoma. The present review seeks to provide an overview of the present and new treatment strategies in the management of glaucoma. The treatment strategies are divided into current available glaucoma medications, new pressure lowering targets, prospective neuroprotective interventions, and finally possible neuroregenrative strategies.
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Affiliation(s)
- Kolko M
- Department of Neuroscience and Pharmacology, the Panum Institute, University of Copenhagen, Denmark ; Department of Ophthalmology, Roskilde University Hospital, Copenhagen, Denmark ; Center of Healthy Aging, Department of Cellular and Molecular Medicine, the Panum Institute, University of Copenhagen, Denmark
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