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Cooper ML, Calkins DJ. Beyond hypertrophy: Changing views of astrocytes in glaucoma. Vision Res 2024; 223:108461. [PMID: 39059109 DOI: 10.1016/j.visres.2024.108461] [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: 05/23/2024] [Revised: 07/11/2024] [Accepted: 07/15/2024] [Indexed: 07/28/2024]
Abstract
Astrocytes serve multiple roles in helping to maintain homeostatic physiology of central nervous system tissue, ranging from metabolic support to coupling between vascular and neural elements. Astrocytes are especially critical in axonal tracts such as the optic nerve, where axons propagate energy-demanding action potentials great distances. In disease, astrocyte remodeling is a dynamic, multifaceted process that is often over-simplified between states of quiescence and reactivity. In glaucoma, axon degeneration in the optic nerve is characterized by progressive stages. So too is astrocyte remodeling. Here, using quantitative analysis of light and electron micrographs of myelinated optic nerve sections from the DBA/2J mouse model of glaucoma, we offer further insight into how astrocyte organization reflects stages of degeneration. This analysis indicates that even as axons degenerate, astrocyte gliosis in the nerve increases without abject proliferation, similar to results in the DBA/2J retina. Gliosis is accompanied by reorganization. As axons expand prior to frank degeneration, astrocyte processes retract from the extra-axonal space and reorient towards the nerve edge. After a critical threshold of expansion, axons drop out, and astrocyte processes distribute more evenly across the nerve reflecting gliosis. This multi-stage process likely reflects local rather than global cues from axons and the surrounding tissue that induce rapid reorganization to promote axon survival and extend functionality of the nerve.
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Affiliation(s)
- Melissa L Cooper
- Neuroscience Institute, NYU Grossman School of Medicine, New York, NY, USA
| | - David J Calkins
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.
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2
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Zhou X, Rong R, Liang G, Wu Y, Xu C, Xiao H, Ji D, Xia X. Self-Assembly Hypoxic and ROS Dual Response Nano Prodrug as a New Therapeutic Approach for Glaucoma Treatments. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2407043. [PMID: 39229928 DOI: 10.1002/advs.202407043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2024] [Revised: 08/24/2024] [Indexed: 09/05/2024]
Abstract
Glaucoma is an irreversible blinding eye disease characterized by retinal ganglion cell (RGC) death.Previous studies have demonstrated that protecting mitochondria and activating the CaMKII/CREB signaling pathway can effectively protect RGC and axon. However, currently treatments are often unsatisfactory, and the pathogenesis of glaucoma requires further elucidation. In this study, a ROS-responsive dual drug conjugate (OLN monomer) is first designed that simultaneously bonds nicotinamide and oleic acid. The conjugate self-assembled into nanoparticles (uhOLN-NPs) through the aggregation of multiple micelles and possesses ROS scavenging capability. Then, a polymer with a hypoxic response function is designed, which encapsulates uhOLN-NPs to form nanoparticles with hypoxic and ROS responses (HOLN-NPs). Under hypoxia in RGCs, the azo bond of HOLN-NPs breaks and releases uhOLN-NPs. Meanwhile, under high ROS conditions, the thioketone bond broke, leading to the dissociation of nano-prodrug. The released nicotinamide and oleic acid co-scavenge ROS and activate the CaMKII/CREB pathway, protecting mitochondria in RGCs. HOLN-NPs exhibit a significantly superior protective effect on R28 cells in glutamate models of glaucoma. The accumulation of HOLN-NPs in retinal RGCs lead to significant inhibition of RGC apoptosis and axonal damage in vivo. Notably, HOLN-NPs provide a new therapeutic approach for patients with neurodegenerative disease.
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Affiliation(s)
- Xuezhi Zhou
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, P. R. China
- Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, 410008, P. R. China
- National Clinical Research Center for Geriatric Diseases, Central South University, Changsha, Hunan, 410008, P. R. China
| | - Rong Rong
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, P. R. China
- Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, 410008, P. R. China
- National Clinical Research Center for Geriatric Diseases, Central South University, Changsha, Hunan, 410008, P. R. China
| | - Ganghao Liang
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Yukun Wu
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, P. R. China
- Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, 410008, P. R. China
- National Clinical Research Center for Geriatric Diseases, Central South University, Changsha, Hunan, 410008, P. R. China
| | - Chun Xu
- School of Dentistry, The University of Queensland, Brisbane, 4006, Australia
| | - Haihua Xiao
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Dan Ji
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, P. R. China
- Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, 410008, P. R. China
- National Clinical Research Center for Geriatric Diseases, Central South University, Changsha, Hunan, 410008, P. R. China
| | - Xiaobo Xia
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, P. R. China
- Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, 410008, P. R. China
- National Clinical Research Center for Geriatric Diseases, Central South University, Changsha, Hunan, 410008, P. R. China
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3
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Maciulaitiene R, Kalesnykas G, Pauza DH, Januleviciene I. A combination of topical and systemic administration of brimonidine is neuroprotective in the murine optic nerve crush model. PLoS One 2024; 19:e0308671. [PMID: 39116180 PMCID: PMC11309405 DOI: 10.1371/journal.pone.0308671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Accepted: 07/22/2024] [Indexed: 08/10/2024] Open
Abstract
Glaucoma is a multifactorial optic neuropathy that primarily affecting retinal ganglion cells (RGC). Brimonidine is an intraocular pressure-lowering drug with reported neuroprotective properties. This study aimed to compare the neuroprotective effects of topical and intraperitoneal (IP) brimonidine on RGCs from different retinal segments in a murine optic nerve crush (ONC) model. METHODS forty-one Balb/c mice underwent unilateral ONC and were divided into three study groups: fifteen animals received saline drops twice per day and two additional IP injections of saline; fourteen mice received brimonidine drops twice per day; and 12 mice received brimonidine eye drops twice per day and two additional IP brimonidine injections. Animals were sacrificed seven days post-ONC, and immunohistochemical staining of retinal whole mounts was performed using neuronal NeuN and GFAP staining. Microscopic pictures of the central, middle, and peripheral regions of the retina were taken. The density of the retinal cells was assessed. RESULTS The total RGC density after ONC and RGC densities in all retinal eccentricities were significantly higher in the brimonidine eye drop and IP combination treatment group than in the saline drop + saline IP, and brimonidine drop treatment groups. CONCLUSIONS brimonidine eye drops supplemented with IP brimonidine injections improved RGC survival in a preclinical model of ONC.
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Affiliation(s)
- Ruta Maciulaitiene
- Department of Ophthalmology, Academy of Medicine, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Giedrius Kalesnykas
- Experimentica Ltd., Kuopio, Finland
- Experimentica UAB, Vilnius, Lithuania
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Dainius Haroldas Pauza
- Academy of Medicine, Institute of Anatomy, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Ingrida Januleviciene
- Department of Ophthalmology, Academy of Medicine, Lithuanian University of Health Sciences, Kaunas, Lithuania
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4
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Durmaz E, Dribika L, Kutnyanszky M, Mead B. Utilizing extracellular vesicles as a drug delivery system in glaucoma and RGC degeneration. J Control Release 2024; 372:209-220. [PMID: 38880332 DOI: 10.1016/j.jconrel.2024.06.029] [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: 02/12/2024] [Revised: 06/10/2024] [Accepted: 06/12/2024] [Indexed: 06/18/2024]
Abstract
Retinal diseases are the leading cause of blindness, resulting in irreversible degeneration and death of retinal neurons. One such cell type, the retinal ganglion cell (RGC), is responsible for connecting the retina to the rest of the brain through its axons that make up the optic nerve and is the primary cell lost in glaucoma and traumatic optic neuropathy. To date, different therapeutic strategies have been investigated to protect RGCs from death and preserve vision, yet currently available strategies are restricted to treating neuron loss by reducing intraocular pressure. A major barrier identified by these studies is drug delivery to RGCs, which is in large part due to drug stability, short duration time at target, low delivery efficiency, and undesired off-target effects. Therefore, a delivery system to deal with these problems is needed to ensure maximum benefit from the candidate therapeutic material. Extracellular vesicles (EV), nanocarriers released by all cells, are lipid membranes encapsulating RNAs, proteins, and lipids. As they naturally shuttle these encapsulated compounds between cells for communicative purposes, they may be exploitable and offer opportunities to overcome hurdles in retinal drug delivery, including drug stability, drug molecular weight, barriers in the retina, and drug adverse effects. Here, we summarize the potential of an EV drug delivery system, discussing their superiorities and potential application to target RGCs.
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Affiliation(s)
- Esmahan Durmaz
- Cardiff University, School of Optometry & Vision Sciences, Cardiff, UK.
| | | | | | - Ben Mead
- Cardiff University, School of Optometry & Vision Sciences, Cardiff, UK.
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5
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Van Hook MJ, McCool S. Enhanced Synaptic Inhibition in the Dorsolateral Geniculate Nucleus in a Mouse Model of Glaucoma. eNeuro 2024; 11:ENEURO.0263-24.2024. [PMID: 38937109 PMCID: PMC11242868 DOI: 10.1523/eneuro.0263-24.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2024] [Accepted: 06/20/2024] [Indexed: 06/29/2024] Open
Abstract
Elevated intraocular pressure (IOP) triggers glaucoma by damaging the output neurons of the retina called retinal ganglion cells (RGCs). This leads to the loss of RGC signaling to visual centers of the brain such as the dorsolateral geniculate nucleus (dLGN), which is critical for processing and relaying information to the cortex for conscious vision. In response to altered levels of activity or synaptic input, neurons can homeostatically modulate postsynaptic neurotransmitter receptor numbers, allowing them to scale their synaptic responses to stabilize spike output. While prior work has indicated unaltered glutamate receptor properties in the glaucomatous dLGN, it is unknown whether glaucoma impacts dLGN inhibition. Here, using DBA/2J mice, which develop elevated IOP beginning at 6-7 months of age, we tested whether the strength of inhibitory synapses on dLGN thalamocortical relay neurons is altered in response to the disease state. We found an enhancement of feedforward disynaptic inhibition arising from local interneurons along with increased amplitude of quantal inhibitory synaptic currents. A combination of immunofluorescence staining for the γ-aminobutyric acid (GABA)A-α1 receptor subunit, peak-scaled nonstationary fluctuation analysis, and measures of homeostatic synaptic scaling pointed to an ∼1.4-fold increase in GABA receptors at postsynaptic inhibitory synapses, although several pieces of evidence indicate a nonuniform scaling across inhibitory synapses within individual relay neurons. Together, these results indicate an increase in inhibitory synaptic strength in the glaucomatous dLGN, potentially pointing toward homeostatic compensation for disruptions in network and neuronal function triggered by increased IOP.
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Affiliation(s)
- Matthew J Van Hook
- Department of Ophthalmology and Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, Nebraska 68198
- Departments of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska 68198
| | - Shaylah McCool
- Department of Ophthalmology and Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, Nebraska 68198
- Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska 68198
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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] [MESH Headings] [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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7
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Zhang Y, Huang S, Xie B, Zhong Y. Aging, Cellular Senescence, and Glaucoma. Aging Dis 2024; 15:546-564. [PMID: 37725658 PMCID: PMC10917531 DOI: 10.14336/ad.2023.0630-1] [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: 01/20/2023] [Accepted: 06/30/2023] [Indexed: 09/21/2023] Open
Abstract
Aging is one of the most serious risk factors for glaucoma, and according to age-standardized prevalence, glaucoma is the second leading cause of legal blindness worldwide. Cellular senescence is a hallmark of aging that is defined by a stable exit from the cell cycle in response to cellular damage and stress. The potential mechanisms underlying glaucomatous cellular senescence include oxidative stress, DNA damage, mitochondrial dysfunction, defective autophagy/mitophagy, and epigenetic modifications. These phenotypes interact and generate a sufficiently stable network to maintain the cell senescent state. Senescent trabecular meshwork (TM) cells, retinal ganglion cells (RGCs) and vascular endothelial cells reportedly accumulate with age and stress and may contribute to glaucoma pathologies. Therapies targeting the suppression or elimination of senescent cells have been found to ameliorate RGC death and improve vision in glaucoma models, suggesting the pivotal role of cellular senescence in the pathophysiology of glaucoma. In this review, we explore the biological links between aging and glaucoma, specifically delving into cellular senescence. Moreover, we summarize the current data on cellular senescence in key target cells associated with the development and clinical phenotypes of glaucoma. Finally, we discuss the therapeutic potential of targeting cellular senescence for the management of glaucoma.
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Affiliation(s)
- Yumeng Zhang
- Department of Ophthalmology, Ruijin Hospital Affiliated Medical School, Shanghai Jiaotong University, Shanghai 200025, China
| | - Shouyue Huang
- Department of Ophthalmology, Ruijin Hospital Affiliated Medical School, Shanghai Jiaotong University, Shanghai 200025, China
| | - Bing Xie
- Correspondence should be addressed to: Dr. Yisheng Zhong () and Bing Xie (), Department of Ophthalmology, Ruijin Hospital Affiliated Medical School, Shanghai Jiaotong University, Shanghai 200025, China
| | - Yisheng Zhong
- Correspondence should be addressed to: Dr. Yisheng Zhong () and Bing Xie (), Department of Ophthalmology, Ruijin Hospital Affiliated Medical School, Shanghai Jiaotong University, Shanghai 200025, China
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8
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Van Hook MJ, McCool S. Nonuniform scaling of synaptic inhibition in the dorsolateral geniculate nucleus in a mouse model of glaucoma. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.27.587036. [PMID: 38586044 PMCID: PMC10996666 DOI: 10.1101/2024.03.27.587036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Elevated intraocular pressure (IOP) triggers glaucoma by damaging the output neurons of the retina called retinal ganglion cells (RGCs). This leads to the loss of RGC signaling to visual centers of the brain such as the dorsolateral geniculate nucleus (dLGN), which is critical for processing and relaying information to the cortex for conscious vision. In response to altered levels of activity or synaptic input, neurons can homeostatically modulate postsynaptic neurotransmitter receptor numbers, allowing them to scale their synaptic responses to stabilize spike output. While prior work has indicated unaltered glutamate receptor properties in the glaucomatous dLGN, it is unknown whether glaucoma impacts dLGN inhibition. Here, using DBA/2J mice, which develop elevated IOP beginning at 6-7 months of age, we tested whether the strength of inhibitory synapses on dLGN thalamocortical relay neurons is altered in response to the disease state. We found an enhancement of feed-forward disynaptic inhibition arising from local interneurons along with increased amplitude of quantal inhibitory synaptic currents. A combination of immunofluorescence staining for the GABA A -α1 receptor subunit, peak-scaled nonstationary fluctuation analysis, and measures of homeostatic synaptic scaling indicated this was the result of an approximately 1.4-fold increase in GABA receptor number at post-synaptic inhibitory synapses, although several pieces of evidence strongly indicate a non-uniform scaling across inhibitory synapses within individual relay neurons. Together, these results indicate an increase in inhibitory synaptic strength in the glaucomatous dLGN, potentially pointing toward homeostatic compensation for disruptions in network and neuronal function triggered by increased IOP. Significance Statement Elevated eye pressure in glaucoma leads to loss of retinal outputs to the dorsolateral geniculate nucleus (dLGN), which is critical for relaying information to the cortex for conscious vision. Alterations in neuronal activity, as could arise from excitatory synapse loss, can trigger homeostatic adaptations to synaptic function that attempt to maintain activity within a meaningful dynamic range, although whether this occurs uniformly at all synapses within a given neuron or is a non-uniform process is debated. Here, using a mouse model of glaucoma, we show that dLGN inhibitory synapses undergo non-uniform upregulation due to addition of post-synaptic GABA receptors. This is likely to be a neuronal adaptation to glaucomatous pathology in an important sub-cortical visual center.
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9
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Arai-Okuda M, Murai Y, Maeda H, Kanamori A, Miki T, Naito T, Sugihara K, Kono M, Tanito M, Onoe H, Hirooka K, Kiuchi Y, Shinohara M, Kusuhara S, Mori S, Ueda K, Sakamoto M, Yamada-Nakanishi Y, Nakamura M. Potentially compromised systemic and local lactate metabolic balance in glaucoma, which could increase retinal glucose and glutamate concentrations. Sci Rep 2024; 14:3683. [PMID: 38355836 PMCID: PMC10866861 DOI: 10.1038/s41598-024-54383-4] [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: 11/18/2023] [Accepted: 02/12/2024] [Indexed: 02/16/2024] Open
Abstract
To investigate the association between lactate metabolism and glaucoma, we conducted a multi-institutional cross-sectional clinical study and a retinal metabolomic analysis of mice with elevated intraocular pressure (IOP) induced by intracameral microbead injection. We compared lactate concentrations in serum and aqueous humor in age-matched 64 patients each with primary open-angle glaucoma (POAG) and cataract. Neither serum nor aqueous humor lactate concentrations differed between the two groups. Multiple regression analysis revealed that only body mass index showed a significant positive correlation with serum and aqueous humor lactate concentration in POAG patients (rs = 0.376, P = 0.002, and rs = 0.333, P = 0.007, respectively), but not in cataract patients. L-Lactic acid was one of the most abundantly detected metabolites in mouse retinas with gas chromatography and mass spectrometry, but there were no significant differences among control, 2-week, and 4-week IOP elevation groups. After 4 weeks of elevated IOP, D-glucose and L-glutamic acid ranked as the top two for a change in raised concentration, roughly sevenfold and threefold, respectively (ANOVA, P = 0.004; Tukey-Kramer, P < 0.05). Glaucoma may disrupt the systemic and intraocular lactate metabolic homeostasis, with a compensatory rise in glucose and glutamate in the retina.
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Affiliation(s)
- Mina Arai-Okuda
- Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan
| | - Yusuke Murai
- Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan
| | | | - Akiyasu Kanamori
- Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan
- Kanamori Eye Clinic, Akashi, Japan
| | | | | | - Kazunobu Sugihara
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan
| | - Michihiro Kono
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan
| | - Masaki Tanito
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan
| | - Hiromitsu Onoe
- Department of Ophthalmology and Visual Science, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan
| | - Kazuyuki Hirooka
- Department of Ophthalmology and Visual Science, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan
| | - Yoshiaki Kiuchi
- Department of Ophthalmology and Visual Science, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan
| | - Masakazu Shinohara
- Division of Molecular Epidemiology, Department of Future Medical Sciences, Kobe University Graduate School of Medicine, Kobe, Japan
- The Integrated Center for Mass Spectrometry, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Sentaro Kusuhara
- Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan
| | - Sotaro Mori
- Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan
| | - Kaori Ueda
- Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan
| | - Mari Sakamoto
- Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan
| | - Yuko Yamada-Nakanishi
- Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan
| | - Makoto Nakamura
- Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan.
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10
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Wareham LK, Baratta RO, Del Buono BJ, Schlumpf E, Calkins DJ. Collagen in the central nervous system: contributions to neurodegeneration and promise as a therapeutic target. Mol Neurodegener 2024; 19:11. [PMID: 38273335 PMCID: PMC10809576 DOI: 10.1186/s13024-024-00704-0] [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: 09/27/2023] [Accepted: 01/10/2024] [Indexed: 01/27/2024] Open
Abstract
The extracellular matrix is a richly bioactive composition of substrates that provides biophysical stability, facilitates intercellular signaling, and both reflects and governs the physiological status of the local microenvironment. The matrix in the central nervous system (CNS) is far from simply an inert scaffold for mechanical support, instead conducting an active role in homeostasis and providing broad capacity for adaptation and remodeling in response to stress that otherwise would challenge equilibrium between neuronal, glial, and vascular elements. A major constituent is collagen, whose characteristic triple helical structure renders mechanical and biochemical stability to enable bidirectional crosstalk between matrix and resident cells. Multiple members of the collagen superfamily are critical to neuronal maturation and circuit formation, axon guidance, and synaptogenesis in the brain. In mature tissue, collagen interacts with other fibrous proteins and glycoproteins to sustain a three-dimensional medium through which complex networks of cells can communicate. While critical for matrix scaffolding, collagen in the CNS is also highly dynamic, with multiple binding sites for partnering matrix proteins, cell-surface receptors, and other ligands. These interactions are emerging as critical mediators of CNS disease and injury, particularly regarding changes in matrix stiffness, astrocyte recruitment and reactivity, and pro-inflammatory signaling in local microenvironments. Changes in the structure and/or deposition of collagen impact cellular signaling and tissue biomechanics in the brain, which in turn can alter cellular responses including antigenicity, angiogenesis, gliosis, and recruitment of immune-related cells. These factors, each involving matrix collagen, contribute to the limited capacity for regeneration of CNS tissue. Emerging therapeutics that attempt to rebuild the matrix using peptide fragments, including collagen-enriched scaffolds and mimetics, hold great potential to promote neural repair and regeneration. Recent evidence from our group and others indicates that repairing protease-degraded collagen helices with mimetic peptides helps restore CNS tissue and promote neuronal survival in a broad spectrum of degenerative conditions. Restoration likely involves bolstering matrix stiffness to reduce the potential for astrocyte reactivity and local inflammation as well as repairing inhibitory binding sites for immune-signaling ligands. Facilitating repair rather than endogenous replacement of collagen degraded by disease or injury may represent the next frontier in developing therapies based on protection, repair, and regeneration of neurons in the central nervous system.
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Affiliation(s)
- Lauren K Wareham
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute , Vanderbilt University Medical Center, 1161 21st Avenue S, 37232, Nashville, TN, USA
| | - Robert O Baratta
- Stuart Therapeutics, Inc., 411 SE Osceola St, 34994, Stuart, FL, USA
| | - Brian J Del Buono
- Stuart Therapeutics, Inc., 411 SE Osceola St, 34994, Stuart, FL, USA
| | - Eric Schlumpf
- Stuart Therapeutics, Inc., 411 SE Osceola St, 34994, Stuart, FL, USA
| | - David J Calkins
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute , Vanderbilt University Medical Center, 1161 21st Avenue S, 37232, Nashville, TN, USA
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11
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Rozpędek-Kamińska W, Galita G, Saramowicz K, Granek Z, Barczuk J, Siwecka N, Pytel D, Majsterek I. Evaluation of the LDN-0060609 PERK Inhibitor as a Selective Treatment for Primary Open-Angle Glaucoma: An In Vitro Study on Human Retinal Astrocytes. Int J Mol Sci 2024; 25:728. [PMID: 38255802 PMCID: PMC10815359 DOI: 10.3390/ijms25020728] [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: 11/13/2023] [Revised: 12/23/2023] [Accepted: 01/03/2024] [Indexed: 01/24/2024] Open
Abstract
The term glaucoma encompasses various neurodegenerative eye disorders, among which the most common is primary open-angle glaucoma (POAG). Recently, the essential role of human retinal astrocytes (HRA) in glaucoma progression has been placed in the spotlight. It has been found that placing the endoplasmic reticulum (ER) under stress and activating PERK leads to apoptosis of HRA cells, which inhibits their neuroprotective effect in the course of glaucoma. Therefore, the aim of the present study was to evaluate the effectiveness of the small-molecule PERK inhibitor LDN-0060609 in countering ER stress conditions induced in HRA cells in vitro. The activity of LDN-0060609 was studied in terms of protein and mRNA expression, cytotoxicity, genotoxicity, caspase-3 level and cell cycle progression. LDN-0060609 at 25 μM proved to be a potent inhibitor of the major PERK substrate, p-eIF2α (49% inhibition). The compound markedly decreased the expression of pro-apoptotic ER stress-related genes (ATF4, DDIT3, BAX and Bcl-2). Treatment with LDN-0060609 significantly increased cell viability, decreased genotoxicity and caspase-3 levels, and restored cell cycle distribution in HRA cells with activated ER stress conditions. These findings indicate that the small-molecule PERK inhibitor LDN-0060609 can potentially be developed into a novel anti-glaucoma agent.
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Affiliation(s)
- Wioletta Rozpędek-Kamińska
- Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, 90-419 Lodz, Poland; (W.R.-K.); (G.G.); (K.S.); (Z.G.); (J.B.); (N.S.)
| | - Grzegorz Galita
- Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, 90-419 Lodz, Poland; (W.R.-K.); (G.G.); (K.S.); (Z.G.); (J.B.); (N.S.)
| | - Kamil Saramowicz
- Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, 90-419 Lodz, Poland; (W.R.-K.); (G.G.); (K.S.); (Z.G.); (J.B.); (N.S.)
| | - Zuzanna Granek
- Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, 90-419 Lodz, Poland; (W.R.-K.); (G.G.); (K.S.); (Z.G.); (J.B.); (N.S.)
| | - Julia Barczuk
- Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, 90-419 Lodz, Poland; (W.R.-K.); (G.G.); (K.S.); (Z.G.); (J.B.); (N.S.)
| | - Natalia Siwecka
- Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, 90-419 Lodz, Poland; (W.R.-K.); (G.G.); (K.S.); (Z.G.); (J.B.); (N.S.)
| | - Dariusz Pytel
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC 29425, USA;
| | - Ireneusz Majsterek
- Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, 90-419 Lodz, Poland; (W.R.-K.); (G.G.); (K.S.); (Z.G.); (J.B.); (N.S.)
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12
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Zueva MV, Neroeva NV, Zhuravleva AN, Bogolepova AN, Kotelin VV, Fadeev DV, Tsapenko IV. Fractal Phototherapy in Maximizing Retina and Brain Plasticity. ADVANCES IN NEUROBIOLOGY 2024; 36:585-637. [PMID: 38468055 DOI: 10.1007/978-3-031-47606-8_31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
The neuroplasticity potential is reduced with aging and impairs during neurodegenerative diseases and brain and visual system injuries. This limits the brain's capacity to repair the structure and dynamics of its activity after lesions. Maximization of neuroplasticity is necessary to provide the maximal CNS response to therapeutic intervention and adaptive reorganization of neuronal networks in patients with degenerative pathology and traumatic injury to restore the functional activity of the brain and retina.Considering the fractal geometry and dynamics of the healthy brain and the loss of fractality in neurodegenerative pathology, we suggest that the application of self-similar visual signals with a fractal temporal structure in the stimulation therapy can reactivate the adaptive neuroplasticity and enhance the effectiveness of neurorehabilitation. This proposition was tested in the recent studies. Patients with glaucoma had a statistically significant positive effect of fractal photic therapy on light sensitivity and the perimetric MD index, which shows that methods of fractal stimulation can be a novel nonpharmacological approach to neuroprotective therapy and neurorehabilitation. In healthy rabbits, it was demonstrated that a long-term course of photostimulation with fractal signals does not harm the electroretinogram (ERG) and retina structure. Rabbits with modeled retinal atrophy showed better dynamics of the ERG restoration during daily stimulation therapy for a week in comparison with the controls. Positive changes in the retinal function can indirectly suggest the activation of its adaptive plasticity and the high potential of stimulation therapy with fractal visual stimuli in a nonpharmacological neurorehabilitation, which requires further study.
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Affiliation(s)
- Marina V Zueva
- Department of Clinical Physiology of Vision, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Natalia V Neroeva
- Department of Pathology of the Retina and Optic Nerve, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Anastasia N Zhuravleva
- Department of Glaucoma, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Anna N Bogolepova
- Department of neurology, neurosurgery and medical genetics, Pirogov Russian National Research Medical University, Moscow, Russia
| | - Vladislav V Kotelin
- Department of Clinical Physiology of Vision, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Denis V Fadeev
- Scientific Experimental Center Department, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Irina V Tsapenko
- Department of Clinical Physiology of Vision, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
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13
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Basavarajappa D, Galindo-Romero C, Gupta V, Agudo-Barriuso M, Gupta VB, Graham SL, Chitranshi N. Signalling pathways and cell death mechanisms in glaucoma: Insights into the molecular pathophysiology. Mol Aspects Med 2023; 94:101216. [PMID: 37856930 DOI: 10.1016/j.mam.2023.101216] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 09/25/2023] [Accepted: 10/02/2023] [Indexed: 10/21/2023]
Abstract
Glaucoma is a complex multifactorial eye disease manifesting in retinal ganglion cell (RGC) death and optic nerve degeneration, ultimately causing irreversible vision loss. Research in recent years has significantly enhanced our understanding of RGC degenerative mechanisms in glaucoma. It is evident that high intraocular pressure (IOP) is not the only contributing factor to glaucoma pathogenesis. The equilibrium of pro-survival and pro-death signalling pathways in the retina strongly influences the function and survival of RGCs and optic nerve axons in glaucoma. Molecular evidence from human retinal tissue analysis and a range of experimental models of glaucoma have significantly contributed to unravelling these mechanisms. Accumulating evidence reveals a wide range of molecular signalling pathways that can operate -either alone or via intricate networks - to induce neurodegeneration. The roles of several molecules, including neurotrophins, interplay of intracellular kinases and phosphates, caveolae and adapter proteins, serine proteases and their inhibitors, nuclear receptors, amyloid beta and tau, and how their dysfunction affects retinal neurons are discussed in this review. We further underscore how anatomical alterations in various animal models exhibiting RGC degeneration and susceptibility to glaucoma-related neuronal damage have helped to characterise molecular mechanisms in glaucoma. In addition, we also present different regulated cell death pathways that play a critical role in RGC degeneration in glaucoma.
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Affiliation(s)
- Devaraj Basavarajappa
- Macquarie Medical School, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia.
| | - Caridad Galindo-Romero
- Experimental Ophthalmology Group, Instituto Murciano de Investigación Biosanitaria Virgen de la Arrixaca (IMIB-Arrixaca) & Ophthalmology Department, Universidad de Murcia, Murcia, Spain
| | - Vivek Gupta
- Macquarie Medical School, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Marta Agudo-Barriuso
- Experimental Ophthalmology Group, Instituto Murciano de Investigación Biosanitaria Virgen de la Arrixaca (IMIB-Arrixaca) & Ophthalmology Department, Universidad de Murcia, Murcia, Spain
| | - Veer B Gupta
- School of Medicine, Deakin University, Melbourne, VIC, Australia
| | - Stuart L Graham
- Macquarie Medical School, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Nitin Chitranshi
- Macquarie Medical School, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia.
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14
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Bou Ghanem GO, Koktysh D, Baratta RO, Del Buono BJ, Schlumpf E, Wareham LK, Calkins DJ. Collagen Mimetic Peptides Promote Repair of MMP-1-Damaged Collagen in the Rodent Sclera and Optic Nerve Head. Int J Mol Sci 2023; 24:17031. [PMID: 38069354 PMCID: PMC10707085 DOI: 10.3390/ijms242317031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/20/2023] [Accepted: 11/28/2023] [Indexed: 12/18/2023] Open
Abstract
The structural and biomechanical properties of collagen-rich ocular tissues, such as the sclera, are integral to ocular function. The degradation of collagen in such tissues is associated with debilitating ophthalmic diseases such as glaucoma and myopia, which often lead to visual impairment. Collagen mimetic peptides (CMPs) have emerged as an effective treatment to repair damaged collagen in tissues of the optic projection, such as the retina and optic nerve. In this study, we used atomic force microscopy (AFM) to assess the potential of CMPs in restoring tissue stiffness in the optic nerve head (ONH), including the peripapillary sclera (PPS) and the glial lamina. Using rat ONH tissue sections, we induced collagen damage with MMP-1, followed by treatment with CMP-3 or vehicle. MMP-1 significantly reduced the Young's modulus of both the PPS and the glial lamina, indicating tissue softening. Subsequent CMP-3 treatment partially restored tissue stiffness in both the PPS and the glial lamina. Immunohistochemical analyses revealed reduced collagen fragmentation after MMP-1 digestion in CMP-3-treated tissues compared to vehicle controls. In summary, these results demonstrate the potential of CMPs to restore collagen stiffness and structure in ONH tissues following enzymatic damage. CMPs may offer a promising therapeutic avenue for preserving vision in ocular disorders involving collagen remodeling and degradation.
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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 37232, USA;
| | - Dmitry Koktysh
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, TN 37212, USA
| | | | | | - Eric Schlumpf
- Stuart Therapeutics, Inc., Stuart, FL 34994, USA; (R.O.B.); (E.S.)
| | - Lauren K. Wareham
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA;
| | - David J. Calkins
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA;
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15
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Jayaram H, Kolko M, Friedman DS, Gazzard G. Glaucoma: now and beyond. Lancet 2023; 402:1788-1801. [PMID: 37742700 DOI: 10.1016/s0140-6736(23)01289-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 06/11/2023] [Accepted: 06/19/2023] [Indexed: 09/26/2023]
Abstract
The glaucomas are a group of conditions leading to irreversible sight loss and characterised by progressive loss of retinal ganglion cells. Although not always elevated, intraocular pressure is the only modifiable risk factor demonstrated by large clinical trials. It remains the leading cause of irreversible blindness, but timely treatment to lower intraocular pressure is effective at slowing the rate of vision loss from glaucoma. Methods for lowering intraocular pressure include laser treatments, topical medications, and surgery. Although modern surgical innovations aim to be less invasive, many have been introduced with little supporting evidence from randomised controlled trials. Many cases remain undiagnosed until the advanced stages of disease due to the limitations of screening and poor access to opportunistic case finding. Future research aims to generate evidence for intraocular pressure-independent neuroprotective treatments, personalised treatment through genetic risk profiling, and exploration of potential advanced cellular and gene therapies.
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Affiliation(s)
- Hari Jayaram
- Glaucoma Service, Moorfields Eye Hospital NHS Foundation Trust, London, UK; UCL Institute of Ophthalmology, London, UK; National Institute for Health and Care Research Moorfields Biomedical Research Centre, London, UK
| | - Miriam Kolko
- Copenhagen University Hospital, Rigshospitalet, Glostrup, Denmark; University of Copenhagen, Department of Drug Design and Pharmacology, Copenhagen, Denmark
| | - David S Friedman
- Massachusetts Eye and Ear Hospital, Glaucoma Center of Excellence, Boston, MA, USA; Harvard University, Boston, MA, USA
| | - Gus Gazzard
- Glaucoma Service, Moorfields Eye Hospital NHS Foundation Trust, London, UK; UCL Institute of Ophthalmology, London, UK; National Institute for Health and Care Research Moorfields Biomedical Research Centre, London, UK.
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16
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Wurl JA, Mac Nair CE, Dietz JA, Shestopalov VI, Nickells RW. Contralateral Astrocyte Response to Acute Optic Nerve Damage Is Mitigated by PANX1 Channel Activity. Int J Mol Sci 2023; 24:15641. [PMID: 37958624 PMCID: PMC10647301 DOI: 10.3390/ijms242115641] [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: 09/05/2023] [Revised: 10/16/2023] [Accepted: 10/23/2023] [Indexed: 11/15/2023] Open
Abstract
Glial reactivity is considered a hallmark of damage-induced innate immune responses in the central nervous system. In the visual system, unilateral optic nerve damage elicits dramatic glial reactivity in the retina directly affected by the lesion and a similar, albeit more modest, effect in the contralateral eye. Evaluation of astrocyte changes in a mouse model of optic nerve crush indicates that astrocyte reactivity, as a function of retinal coverage and cellular hypertrophy, occurs within both the experimental and contralateral retinas, although the hypertrophic response of the astrocytes in the contralateral eyes is delayed for at least 24 h. Evaluation of astrocytic reactivity as a function of Gfap expression indicates a similar, muted but significant, response in contralateral eyes. This constrained glial response is completely negated by conditional knock out of Panx1 in both astrocytes and Müller cells. Further studies are required to identify if this is an autocrine or a paracrine suppression of astroglial reactivity.
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Affiliation(s)
- Jasmine A. Wurl
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (J.A.W.); (C.E.M.N.); (J.A.D.)
| | - Caitlin E. Mac Nair
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (J.A.W.); (C.E.M.N.); (J.A.D.)
| | - Joel A. Dietz
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (J.A.W.); (C.E.M.N.); (J.A.D.)
| | - Valery I. Shestopalov
- Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, FL 33136, USA;
| | - Robert W. Nickells
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA; (J.A.W.); (C.E.M.N.); (J.A.D.)
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA
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17
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Sharif NA. Electrical, Electromagnetic, Ultrasound Wave Therapies, and Electronic Implants for Neuronal Rejuvenation, Neuroprotection, Axonal Regeneration, and IOP Reduction. J Ocul Pharmacol Ther 2023; 39:477-498. [PMID: 36126293 DOI: 10.1089/jop.2022.0046] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The peripheral nervous system (PNS) of mammals and nervous systems of lower organisms possess significant regenerative potential. In contrast, although neural plasticity can provide some compensation, the central nervous system (CNS) neurons and nerves of adult mammals generally fail to regenerate after an injury or damage. However, use of diverse electrical, electromagnetic and sonographic energy waves are illuminating novel ways to stimulate neuronal differentiation, proliferation, neurite growth, and axonal elongation/regeneration leading to various levels of functional recovery in animals and humans afflicted with disorders of the CNS, PNS, retina, and optic nerve. Tools such as acupuncture, electroacupuncture, electroshock therapy, electrical stimulation, transcranial magnetic stimulation, red light therapy, and low-intensity pulsed ultrasound therapy are demonstrating efficacy in treating many different maladies. These include wound healing, partial recovery from motor dysfunctions, recovery from ischemic/reperfusion insults and CNS and ocular remyelination, retinal ganglion cell (RGC) rejuvenation, and RGC axonal regeneration. Neural rejuvenation and axonal growth/regeneration processes involve activation or intensifying of the intrinsic bioelectric waves (action potentials) that exist in every neuronal circuit of the body. In addition, reparative factors released at the nerve terminals and via neuronal dendrites (transmitter substances), extracellular vesicles containing microRNAs and neurotrophins, and intercellular communication occurring via nanotubes aid in reestablishing lost or damaged connections between the traumatized tissues and the PNS and CNS. Many other beneficial effects of the aforementioned treatment paradigms are mediated via gene expression alterations such as downregulation of inflammatory and death-signal genes and upregulation of neuroprotective and cytoprotective genes. These varied techniques and technologies will be described and discussed covering cell-based and animal model-based studies. Data from clinical applications and linkage to human ocular diseases will also be discussed where relevant translational research has been reported.
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Affiliation(s)
- Najam A Sharif
- Global Alliances and External Research, Ophthalmology Innovation Center, Santen Inc., Emeryville, California, USA
- Singapore Eye Research Institute (SERI), Singapore
- SingHealth Duke-NUS Ophthalmology and Visual Sciences Academic Clinical Programme, Duke-National University of Singapore Medical School, Singapore
- Department of Surgery and Cancer, Imperial College of Science and Technology, London, United Kingdom
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University, Houston, Texas, USA
- Department of Pharmacology and Neuroscience, University of North Texas Health Sciences Center, Fort Worth, Texas, USA
- Department of Pharmacy Sciences, Creighton University, Omaha, Nebraska, USA
- Insitute of Ophthalmology, University College London (UCL), London, United Kingdom
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18
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Canovai A, Tribble JR, Jöe M, Westerlund DY, Amato R, Trounce IA, Dal Monte M, Williams PA. Pyrroloquinoline quinone drives ATP synthesis in vitro and in vivo and provides retinal ganglion cell neuroprotection. Acta Neuropathol Commun 2023; 11:146. [PMID: 37684640 PMCID: PMC10486004 DOI: 10.1186/s40478-023-01642-6] [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: 07/07/2023] [Accepted: 08/23/2023] [Indexed: 09/10/2023] Open
Abstract
Retinal ganglion cells are highly metabolically active requiring strictly regulated metabolism and functional mitochondria to keep ATP levels in physiological range. Imbalances in metabolism and mitochondrial mechanisms can be sufficient to induce a depletion of ATP, thus altering retinal ganglion cell viability and increasing cell susceptibility to death under stress. Altered metabolism and mitochondrial abnormalities have been demonstrated early in many optic neuropathies, including glaucoma, autosomal dominant optic atrophy, and Leber hereditary optic neuropathy. Pyrroloquinoline quinone (PQQ) is a quinone cofactor and is reported to have numerous effects on cellular and mitochondrial metabolism. However, the reported effects are highly context-dependent, indicating the need to study the mechanism of PQQ in specific systems. We investigated whether PQQ had a neuroprotective effect under different retinal ganglion cell stresses and assessed the effect of PQQ on metabolic and mitochondrial processes in cortical neuron and retinal ganglion cell specific contexts. We demonstrated that PQQ is neuroprotective in two models of retinal ganglion cell degeneration. We identified an increased ATP content in healthy retinal ganglion cell-related contexts both in in vitro and in vivo models. Although PQQ administration resulted in a moderate effect on mitochondrial biogenesis and content, a metabolic variation in non-diseased retinal ganglion cell-related tissues was identified after PQQ treatment. These results suggest the potential of PQQ as a novel neuroprotectant against retinal ganglion cell death.
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Affiliation(s)
- Alessio Canovai
- Division of Eye and Vision, Department of Clinical Neuroscience, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
- Department of Biology, University of Pisa, Pisa, Italy
| | - James R. Tribble
- Division of Eye and Vision, Department of Clinical Neuroscience, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
| | - Melissa Jöe
- Division of Eye and Vision, Department of Clinical Neuroscience, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
| | - Daniela Y. Westerlund
- Division of Eye and Vision, Department of Clinical Neuroscience, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
| | - Rosario Amato
- Department of Biology, University of Pisa, Pisa, Italy
| | - Ian A. Trounce
- Department of Surgery, Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Ophthalmology, University of Melbourne, Melbourne, VIC Australia
| | | | - Pete A. Williams
- Division of Eye and Vision, Department of Clinical Neuroscience, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
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19
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Murai Y, Mori S, Okuda M, Kusuhara S, Kurimoto T, Nakamura M. Effects of Elevated Intraocular Pressure on Retinal Ganglion Cell Density and Expression and Interaction of Retinal Aquaporin 9 and Monocarboxylate Transporters. Ophthalmic Res 2023; 66:1222-1229. [PMID: 37647868 PMCID: PMC10614569 DOI: 10.1159/000533497] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 08/04/2023] [Indexed: 09/01/2023]
Abstract
INTRODUCTION Astrocyte-to-neuron lactate shuttle (ANLS) plays an important role in the energy metabolism of neurons, including retinal ganglion cells (RGCs). Aquaporin 9 (AQP9), which is an aquaglyceroporin that can transport lactate, may be involved in ANLS together with monocarboxylate transporters (MCTs) to maintain RGC function and survival. This study aimed to investigate the impact of elevated intraocular pressure (IOP) on AQP9-MCT interaction and RGC survival. METHODS IOP was elevated in Aqp9 knock-out (KO) mice and wild-type (WT) littermates by anterior chamber microbead injection. RGC density was measured by TUBB3 immunostaining on retinal flat mounts. Immunolabeling, immunoblot, and immunoprecipitation were conducted to identify and quantitate expressions of AQP9, MCT1, MCT2, and MCT4 in whole retinas and ganglion cell layer (GCL). RESULTS Aqp9 KO and WT mice had similar RGC density at baseline. Microbead injection increased cumulative IOP by approximately 32% up to 4 weeks, resulting in RGC density loss of 42% and 34% in WT and Aqp9 KO mice, respectively, with no statistical difference. In the retina of WT mice, elevated IOP decreased the amount of AQP9, MCT1, and MCT2 protein and changed the AQP9 immunoreactivity and reduced MCT1 and MCT2 immunoreactivities in GCL. Meanwhile, it decreased MCT1 and increased MCT2 that interact with AQP9, without affecting MCT4 expression. Aqp9 gene deletion increased baseline MCT2 expression in the GCL and counteracted IOP elevation regarding MCT1 and MCT2 expressions. CONCLUSION The compensatory upregulation of MCT1 and MCT2 with Aqp9 gene deletion and ocular hypertension may reflect the need to maintain lactate transport in the retina for RGC survival.
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Affiliation(s)
- Yusuke Murai
- Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Sotaro Mori
- Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Mina Okuda
- Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Sentaro Kusuhara
- Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Takuji Kurimoto
- Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Makoto Nakamura
- Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan
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20
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Vasconcelos CFM, Ribas VT, Petrs-Silva H. Shared Molecular Pathways in Glaucoma and Other Neurodegenerative Diseases: Insights from RNA-Seq Analysis and miRNA Regulation for Promising Therapeutic Avenues. Cells 2023; 12:2155. [PMID: 37681887 PMCID: PMC10486375 DOI: 10.3390/cells12172155] [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: 07/29/2023] [Revised: 08/14/2023] [Accepted: 08/21/2023] [Indexed: 09/09/2023] Open
Abstract
Advances in RNA-sequencing technologies have led to the identification of molecular biomarkers for several diseases, including neurodegenerative diseases, such as Alzheimer's, Parkinson's, Huntington's diseases and Amyotrophic Lateral Sclerosis. Despite the nature of glaucoma as a neurodegenerative disorder with several similarities with the other above-mentioned diseases, transcriptional data about this disease are still scarce. microRNAs are small molecules (~17-25 nucleotides) that have been found to be specifically expressed in the CNS as major components of the system regulating the development signatures of neurodegenerative diseases and the homeostasis of the brain. In this review, we sought to identify similarities between the functional mechanisms and the activated pathways of the most common neurodegenerative diseases, as well as to discuss how those mechanisms are regulated by miRNAs, using RNA-Seq as an approach to compare them. We also discuss therapeutically suitable applications for these disease hallmarks in clinical future studies.
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Affiliation(s)
- Carlos Franciney Moreira Vasconcelos
- University of Medicine of Göttingen, 37075 Göttingen, Germany
- Institute of Biophysics Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Vinicius Toledo Ribas
- Institute of Biological Sciences, Universidade Federal de Minas Gerais (ICB/UFMG), Belo Horizonte 31270-901, Brazil;
| | - Hilda Petrs-Silva
- Institute of Biophysics Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
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21
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Holden JM, Wareham LK, Calkins DJ. Retinal astrocyte morphology predicts integration of vascular and neuronal architecture. Front Neurosci 2023; 17:1244679. [PMID: 37621717 PMCID: PMC10445659 DOI: 10.3389/fnins.2023.1244679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 07/24/2023] [Indexed: 08/26/2023] Open
Abstract
Astrocytes are important regulators of blood flow and play a key role in the response to injury and disease in the central nervous system (CNS). Despite having an understanding that structural changes to these cells have consequences for local neurovascular physiology, individual astrocyte morphology remains largely unexplored in the retina. Here, we used MORF3 mice to capture full membranous morphology for over fifteen hundred individual astrocytes in the mouse retina, a highly metabolically active component of the CNS. We demonstrate that retinal astrocytes have been misrepresented as stellate in morphology due to marker use like GFAP and S100β which underestimates cell complexity. We also find that astrocytes contain recurring morphological motifs which are predictive of the underlying neurovascular architecture of the inner retina and suggestive of function. These motifs predict fine sampling and integration of retinal ganglion cell electrical activity with consequences for blood flow regulation. Additionally, our data shows that astrocytes participate in neurovascular interactions to a much greater degree than currently reported. 100% of cells contact the vasculature through one of three mutually exclusive classes of connections. Similarly, 100% of cells contact some neuronal element, be it an RGC axon or soma. Finally, we report that astrocyte morphology depends on retinal eccentricity, with cells appearing compressed near the nerve head and in the periphery. These results reveal a large degree of astrocyte morphological complexity that informs their contribution to neurovascular coupling in the retina.
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Affiliation(s)
- Joseph M. Holden
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, United States
- Vanderbilt Neuroscience Graduate Program, Vanderbilt University, Nashville, TN, United States
| | - Lauren K. Wareham
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, United States
| | - David J. Calkins
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, United States
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22
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Liu P, Chen W, Jiang H, Huang H, Liu L, Fang F, Li L, Feng X, Liu D, Dalal R, Sun Y, Jafar-Nejad P, Ling K, Rigo F, Ye J, Hu Y. Differential effects of SARM1 inhibition in traumatic glaucoma and EAE optic neuropathies. MOLECULAR THERAPY. NUCLEIC ACIDS 2023; 32:13-27. [PMID: 36950280 PMCID: PMC10025007 DOI: 10.1016/j.omtn.2023.02.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 02/23/2023] [Indexed: 03/03/2023]
Abstract
Optic neuropathy is a group of optic nerve (ON) diseases with progressive degeneration of ON and retinal ganglion cells (RGCs). The lack of neuroprotective treatments is a central challenge for this leading cause of irreversible blindness. SARM1 (sterile α and TIR motif-containing protein 1) has intrinsic nicotinamide adenine dinucleotide (NAD+) hydrolase activity that causes axon degeneration by degrading axonal NAD+ significantly after activation by axon injury. SARM1 deletion is neuroprotective in many, but not all, neurodegenerative disease models. Here, we compare two therapy strategies for SARM1 inhibition, antisense oligonucleotide (ASO) and CRISPR, with germline SARM1 deletion in the neuroprotection of three optic neuropathy mouse models. This study reveals that, similar to germline SARM1 knockout in every cell, local retinal SARM1 ASO delivery and adeno-associated virus (AAV)-mediated RGC-specific CRISPR knockdown of SARM1 provide comparable neuroprotection to both RGC somata and axons in the silicone oil-induced ocular hypertension (SOHU) glaucoma model but only protect RGC axons, not somata, after traumatic ON injury. Surprisingly, neither of these two therapy strategies of SARM1 inhibition nor SARM1 germline knockout (KO) benefits RGC or ON survival in the experimental autoimmune encephalomyelitis (EAE)/optic neuritis model. Our studies therefore suggest that SARM1 inhibition by local ASO delivery or AAV-mediated CRISPR is a promising neuroprotective gene therapy strategy for traumatic and glaucomatous optic neuropathies but not for demyelinating optic neuritis.
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Affiliation(s)
- Pingting Liu
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Wei Chen
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Haowen Jiang
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Haoliang Huang
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Liping Liu
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Fang Fang
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Liang Li
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Xue Feng
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Dong Liu
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Roopa Dalal
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Yang Sun
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | | | - Karen Ling
- Ionis Pharmaceuticals, Inc., Carlsbad, CA 92010, USA
| | - Frank Rigo
- Ionis Pharmaceuticals, Inc., Carlsbad, CA 92010, USA
| | - Jiangbin Ye
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Yang Hu
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
- Corresponding author: Yang Hu, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA.
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23
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Boal AM, McGrady NR, Chamling X, Kagitapalli BS, Zack DJ, Calkins DJ, Risner ML. Microfluidic Platforms Promote Polarization of Human-Derived Retinal Ganglion Cells That Model Axonopathy. Transl Vis Sci Technol 2023; 12:1. [PMID: 37010860 PMCID: PMC10080917 DOI: 10.1167/tvst.12.4.1] [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: 12/06/2022] [Accepted: 03/09/2023] [Indexed: 04/04/2023] Open
Abstract
Purpose Axons depend on long-range transport of proteins and organelles which increases susceptibility to metabolic stress in disease. The axon initial segment (AIS) is particularly vulnerable due to the high bioenergetic demand of action potential generation. Here, we prepared retinal ganglion cells derived from human embryonic stem cells (hRGCs) to probe how axonal stress alters AIS morphology. Methods hRGCs were cultured on coverslips or microfluidic platforms. We assayed AIS specification and morphology by immunolabeling against ankyrin G (ankG), an axon-specific protein, and postsynaptic density 95 (PSD-95), a dendrite-specific protein. Using microfluidic platforms that enable fluidic isolation, we added colchicine to the axon compartment to lesion axons. We verified axonopathy by measuring the anterograde axon transport of cholera toxin subunit B and immunolabeling against cleaved caspase 3 (CC3) and phosphorylated neurofilament H (SMI-34). We determined the influence of axon injury on AIS morphology by immunolabeling samples against ankG and measuring AIS distance from soma and length. Results Based on measurements of ankG and PSD-95 immunolabeling, microfluidic platforms promote the formation and separation of distinct somatic-dendritic versus axonal compartments in hRGCs compared to coverslip cultures. Chemical lesioning of axons by colchicine reduced hRGC anterograde axon transport, increased varicosity density, and enhanced expression of CC3 and SMI-34. Interestingly, we found that colchicine selectively affected hRGCs with axon-carrying dendrites by reducing AIS distance from somas and increasing length, thus suggesting reduced capacity to maintain excitability. Conclusions Thus, microfluidic platforms promote polarized hRGCs that enable modeling of axonopathy. Translational Relevance Microfluidic platforms may be used to assay compartmentalized degeneration that occurs during glaucoma.
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Affiliation(s)
- Andrew M. Boal
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Nolan R. McGrady
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Xitiz Chamling
- Wilmer Eye Institute, Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Bhanu S. Kagitapalli
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Donald J. Zack
- Wilmer Eye Institute, Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - David J. Calkins
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Michael L. Risner
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
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24
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Boal AM, McGrady NR, Holden JM, Risner ML, Calkins DJ. Retinal ganglion cells adapt to ionic stress in experimental glaucoma. Front Neurosci 2023; 17:1142668. [PMID: 37051140 PMCID: PMC10083336 DOI: 10.3389/fnins.2023.1142668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 03/10/2023] [Indexed: 03/28/2023] Open
Abstract
IntroductionIdentification of early adaptive and maladaptive neuronal stress responses is an important step in developing targeted neuroprotective therapies for degenerative disease. In glaucoma, retinal ganglion cells (RGCs) and their axons undergo progressive degeneration resulting from stress driven by sensitivity to intraocular pressure (IOP). Despite therapies that can effectively manage IOP many patients progress to vision loss, necessitating development of neuronal-based therapies. Evidence from experimental models of glaucoma indicates that early in the disease RGCs experience altered excitability and are challenged with dysregulated potassium (K+) homeostasis. Previously we demonstrated that certain RGC types have distinct excitability profiles and thresholds for depolarization block, which are associated with sensitivity to extracellular K+.MethodsHere, we used our inducible mouse model of glaucoma to investigate how RGC sensitivity to K+ changes with exposure to elevated IOP.ResultsIn controls, conditions of increased K+ enhanced membrane depolarization, reduced action potential generation, and widened action potentials. Consistent with our previous work, 4 weeks of IOP elevation diminished RGC light-and current-evoked responses. Compared to controls, we found that IOP elevation reduced the effects of increased K+ on depolarization block threshold, with IOP-exposed cells maintaining greater excitability. Finally, IOP elevation did not alter axon initial segment dimensions, suggesting that structural plasticity alone cannot explain decreased K+ sensitivity.DiscussionThus, in response to prolonged IOP elevation RGCs undergo an adaptive process that reduces sensitivity to changes in K+ while diminishing excitability. These experiments give insight into the RGC response to IOP stress and lay the groundwork for mechanistic investigation into targets for neuroprotective therapy.
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25
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Meng Z, You R, Mahmood A, Yan F, Wang Y. Application of Proteomics Analysis and Animal Models in Optic Nerve Injury Diseases. Brain Sci 2023; 13:404. [PMID: 36979214 PMCID: PMC10046207 DOI: 10.3390/brainsci13030404] [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: 01/13/2023] [Revised: 02/08/2023] [Accepted: 02/14/2023] [Indexed: 03/03/2023] Open
Abstract
Optic nerve damage is a common cause of blindness. Optic nerve injury is often accompanied by fundus vascular disease, retinal ganglion cell apoptosis, and changes in retinal thickness. These changes can cause alterations in protein expression within neurons in the retina. Proteomics analysis offers conclusive evidence to decode a biological system. Furthermore, animal models of optic nerve injury made it possible to gain insight into pathological mechanisms, therapeutic targets, and effective treatment of such injuries. Proteomics takes the proteome as the research object and studies protein changes in cells and tissues. At present, a variety of proteomic analysis methods have been widely used in the research of optic nerve injury diseases. This review summarizes the application of proteomic research in optic nerve injury diseases and animal models of optic nerve injury. Additionally, differentially expressed proteins are summarized and analyzed. Various optic nerve injuries, including those associated with different etiologies, are discussed along with their potential therapeutic targets and future directions.
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Affiliation(s)
- Zhaoyang Meng
- Department of Ophthalmology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Ran You
- Department of Ophthalmology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Arif Mahmood
- Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha 410078, China
| | - Fancheng Yan
- Department of Ophthalmology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Yanling Wang
- Department of Ophthalmology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
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26
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Erythropoietin in Glaucoma: From Mechanism to Therapy. Int J Mol Sci 2023; 24:ijms24032985. [PMID: 36769310 PMCID: PMC9917746 DOI: 10.3390/ijms24032985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 01/26/2023] [Accepted: 01/27/2023] [Indexed: 02/05/2023] Open
Abstract
Glaucoma can cause irreversible vision loss and is the second leading cause of blindness worldwide. The disease mechanism is complex and various factors have been implicated in its pathogenesis, including ischemia, excessive oxidative stress, neurotropic factor deprivation, and neuron excitotoxicity. Erythropoietin (EPO) is a hormone that induces erythropoiesis in response to hypoxia. However, studies have shown that EPO also has neuroprotective effects and may be useful for rescuing apoptotic retinal ganglion cells in glaucoma. This article explores the relationship between EPO and glaucoma and summarizes preclinical experiments that have used EPO to treat glaucoma, with an aim to provide a different perspective from the current view that glaucoma is incurable.
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27
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Niu Y, Zhang G, Sun X, He S, Dou G. Distinct Role of Lycium barbarum L. Polysaccharides in Oxidative Stress-Related Ocular Diseases. Pharmaceuticals (Basel) 2023; 16:215. [PMID: 37259363 PMCID: PMC9966716 DOI: 10.3390/ph16020215] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 01/26/2023] [Accepted: 01/28/2023] [Indexed: 09/29/2023] Open
Abstract
Oxidative stress is an imbalance between the increased production of reactive species and reduced antioxidant activity, which can cause a variety of disturbances including ocular diseases. Lycium barbarum polysaccharides (LBPs) are complex polysaccharides isolated from the fruit of L. barbarum, showing distinct roles in antioxidants. Moreover, it is relatively safe and non-toxic. In recent years, the antioxidant activities of LBPs have attracted remarkable attention. In order to illustrate its significance and underlying therapeutic value for vision, we comprehensively review the recent progress on the antioxidant mechanisms of LBP and its potential applications in ocular diseases, including diabetic retinopathy, hypertensive neuroretinopathy, age-related macular degeneration, retinitis pigmentosa, retinal ischemia/reperfusion injury, glaucoma, dry eye syndrome, and diabetic cataract.
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Affiliation(s)
- Yali Niu
- College of Life Sciences, Northwestern University, Xi’an 710069, China
- Department of Ophthalmology, Eye Institute of Chinese PLA, Xijing Hospital, Fourth Military Medical University, Xi’an 710032, China
| | - Guoheng Zhang
- Department of Ophthalmology, Eye Institute of Chinese PLA, Xijing Hospital, Fourth Military Medical University, Xi’an 710032, China
| | - Xiaojia Sun
- Department of Ophthalmology, Eye Institute of Chinese PLA, Xijing Hospital, Fourth Military Medical University, Xi’an 710032, China
| | - Shikun He
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Guorui Dou
- Department of Ophthalmology, Eye Institute of Chinese PLA, Xijing Hospital, Fourth Military Medical University, Xi’an 710032, China
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28
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Loss of Retinogeniculate Synaptic Function in the DBA/2J Mouse Model of Glaucoma. eNeuro 2022; 9:ENEURO.0421-22.2022. [PMID: 36526366 PMCID: PMC9794376 DOI: 10.1523/eneuro.0421-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 11/22/2022] [Accepted: 12/08/2022] [Indexed: 12/23/2022] Open
Abstract
Retinal ganglion cell (RGC) axons comprise the optic nerve and carry information to the dorsolateral geniculate nucleus (dLGN), which is then relayed to the cortex for conscious vision. Glaucoma is a blinding neurodegenerative disease that commonly results from intraocular pressure (IOP)-associated injury leading to RGC axonal pathology, disruption of RGC outputs to the brain, and eventual apoptotic loss of RGC somata. The consequences of elevated IOP and glaucomatous pathology on RGC signaling to the dLGN are largely unknown yet are likely to contribute to vision loss. Here, we used anatomic and physiological approaches to study the structure and function of retinogeniculate (RG) synapses in male and female DBA/2J (D2) mice with inherited glaucoma before and after IOP elevation. D2 mice showed progressive loss of anterograde optic tract transport to the dLGN and vGlut2 labeling of RGC axon terminals while patch-clamp measurements of RG synaptic function showed that synaptic transmission was reduced in 9-month and 12-month D2 mice because of the loss of individual RGC axon inputs. TC neuron dendrites had reduced Sholl complexity at 12 months, suggestive of delayed reorganization following reduced synaptic input. There was no detectable change in RGC density in 11- to 12-month D2 retinas, quantified as the number of ganglion cell layer-residing somata immuno-positive for NeuN and immuno-negative for the amacrine marker choline acetyltransferase (ChAT). Thus, observed synaptic defects appear to precede RGC somatic loss. These findings identify glaucoma-associated and IOP-associated deficits in an important subcortical RGC projection target, shedding light on processes linking IOP to vision loss.
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29
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Silicone Oil-Induced Glaucomatous Neurodegeneration in Rhesus Macaques. Int J Mol Sci 2022; 23:ijms232415896. [PMID: 36555536 PMCID: PMC9781764 DOI: 10.3390/ijms232415896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 12/06/2022] [Accepted: 12/13/2022] [Indexed: 12/15/2022] Open
Abstract
Previously, we developed a simple procedure of intracameral injection of silicone oil (SO) into mouse eyes and established the mouse SOHU (SO-induced ocular hypertension under-detected) glaucoma model with reversible intraocular pressure (IOP) elevation and significant glaucomatous neurodegeneration. Because the anatomy of the non-human primate (NHP) visual system closely resembles that of humans, it is the most likely to predict human responses to diseases and therapies. Here we tried to replicate the mouse SOHU glaucoma model in rhesus macaque monkeys. All six animals that we tested showed significant retinal ganglion cell (RGC) death, optic nerve (ON) degeneration, and visual functional deficits at both 3 and 6 months. In contrast to the mouse SOHU model, however, IOP changed dynamically in these animals, probably due to individual differences in ciliary body tolerance capability. Further optimization of this model is needed to achieve consistent IOP elevation without permanent damage of the ciliary body. The current form of the NHP SOHU model recapitulates the severe degeneration of acute human glaucoma, and is therefore suitable for assessing experimental therapies for neuroprotection and regeneration, and therefore for translating relevant findings into novel and effective treatments for patients with glaucoma and other neurodegenerations.
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30
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Lysyl oxidase-like 1 deficiency alters ultrastructural and biomechanical properties of the peripapillary sclera in mice. Matrix Biol Plus 2022; 16:100120. [PMID: 36060791 PMCID: PMC9436796 DOI: 10.1016/j.mbplus.2022.100120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 08/17/2022] [Indexed: 11/30/2022] Open
Abstract
Lysyl oxidate-like 1 knockout (Loxl1-/-) mice have decreased vision without elevated intraocular pressure. Loxl1-/- mice exhibit biometric changes of the anterior segment of the eye. Loxl1-/- mice have altered elastin and collagen structure in peripapillary sclera. Structural alternations of peripapillary sclera correlate with its increased stiffness in Loxl1-/- mice.
Lysyl oxidase-like 1 encoded by the LOXL1 gene is a member of the lysyl oxidase family of enzymes that are important in the maintenance of extracellular matrix (ECM)-rich tissue. LOXL1 is important for proper elastic fiber formation and mice lacking LOXL1 (Loxl1−/−) exhibit systemic elastic fiber disorders, such as pelvic organ prolapse, a phenotype associated with exfoliation syndrome (XFS) in humans. Patients with XFS have a significant risk of developing exfoliation glaucoma (XFG), a severe form of glaucoma, which is a neurodegenerative condition leading to irreversible blindness if not detected and treated in a timely fashion. Although Loxl1−/− mice have been used extensively to investigate mechanisms of pelvic organ prolapse, studies of eyes in those mice are limited and some showed inconsistent ocular phenotypes. In this study we demonstrate that Loxl1−/− mice have significant anterior segment biometric abnormalities which recapitulate some human XFS features. We then focused on the peripapillary sclera (PPS), a critical structure for maintaining optic nerve health. We discovered quantitative and qualitive changes in ultrastructure of PPS, such as reduced elastic fibers, enlarged collagen fibrils, and transformed collagen lamella organization detected by transmission electron microscopy (TEM). Importantly, these changes corelate with altered tissue biomechanics detected by Atomic Force Microscopy (AFM) of PPS in mice. Together, our results support a crucial role for LOXL1 in ocular tissue structure and biomechanics, and Loxl1−/− mice could be a valuable resource for understanding the role of scleral tissue biomechanics in ocular disease.
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31
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Li L, Feng X, Fang F, Miller DA, Zhang S, Zhuang P, Huang H, Liu P, Liu J, Sredar N, Liu L, Sun Y, Duan X, Goldberg JL, Zhang HF, Hu Y. Longitudinal in vivo Ca 2+ imaging reveals dynamic activity changes of diseased retinal ganglion cells at the single-cell level. Proc Natl Acad Sci U S A 2022; 119:e2206829119. [PMID: 36409915 PMCID: PMC9889883 DOI: 10.1073/pnas.2206829119] [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: 04/19/2022] [Accepted: 10/05/2022] [Indexed: 11/22/2022] Open
Abstract
Retinal ganglion cells (RGCs) are heterogeneous projection neurons that convey distinct visual features from the retina to brain. Here, we present a high-throughput in vivo RGC activity assay in response to light stimulation using noninvasive Ca2+ imaging of thousands of RGCs simultaneously in living mice. Population and single-cell analyses of longitudinal RGC Ca2+ imaging reveal distinct functional responses of RGCs and unprecedented individual RGC activity conversions during traumatic and glaucomatous degeneration. This study establishes a foundation for future in vivo RGC function classifications and longitudinal activity evaluations using more advanced imaging techniques and visual stimuli under normal, disease, and neural repair conditions. These analyses can be performed at both the population and single-cell levels using temporal and spatial information, which will be invaluable for understanding RGC pathophysiology and identifying functional biomarkers for diverse optic neuropathies.
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Affiliation(s)
- Liang Li
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA94304
| | - Xue Feng
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA94304
| | - Fang Fang
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA94304
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha410011, China
| | - David A. Miller
- Department of Biomedical Engineering, Northwestern University, Evanston, IL60208
| | - Shaobo Zhang
- Department of Ophthalmology, University of California San Francisco, San Francisco, CA94143
| | - Pei Zhuang
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA94304
| | - Haoliang Huang
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA94304
| | - Pingting Liu
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA94304
| | - Junting Liu
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA94304
| | - Nripun Sredar
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA94304
| | - Liang Liu
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA94304
| | - Yang Sun
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA94304
| | - Xin Duan
- Department of Ophthalmology, University of California San Francisco, San Francisco, CA94143
| | - Jeffrey L. Goldberg
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA94304
| | - Hao F. Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL60208
| | - Yang Hu
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA94304
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32
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Holden JM, Wareham LK. cGMP signaling: a potential therapeutic target for neurodegeneration in glaucoma? Neural Regen Res 2022; 18:1267-1268. [PMID: 36453407 PMCID: PMC9838148 DOI: 10.4103/1673-5374.360169] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
- Joseph M. Holden
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Lauren K. Wareham
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, USA,Correspondence to: Lauren K. Wareham, .
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33
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Haider AA, Rex TS, Wareham LK. cGMP Signaling in the Neurovascular Unit-Implications for Retinal Ganglion Cell Survival in Glaucoma. Biomolecules 2022; 12:1671. [PMID: 36421684 PMCID: PMC9687235 DOI: 10.3390/biom12111671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 11/07/2022] [Accepted: 11/09/2022] [Indexed: 11/16/2022] Open
Abstract
Glaucoma is a progressive age-related disease of the visual system and the leading cause of irreversible blindness worldwide. Currently, intraocular pressure (IOP) is the only modifiable risk factor for the disease, but even as IOP is lowered, the pathology of the disease often progresses. Hence, effective clinical targets for the treatment of glaucoma remain elusive. Glaucoma shares comorbidities with a multitude of vascular diseases, and evidence in humans and animal models demonstrates an association between vascular dysfunction of the retina and glaucoma pathology. Integral to the survival of retinal ganglion cells (RGCs) is functional neurovascular coupling (NVC), providing RGCs with metabolic support in response to neuronal activity. NVC is mediated by cells of the neurovascular unit (NVU), which include vascular cells, glial cells, and neurons. Nitric oxide-cyclic guanosine monophosphate (NO-cGMP) signaling is a prime mediator of NVC between endothelial cells and neurons, but emerging evidence suggests that cGMP signaling is also important in the physiology of other cells of the NVU. NO-cGMP signaling has been implicated in glaucomatous neurodegeneration in humans and mice. In this review, we explore the role of cGMP signaling in the different cell types of the NVU and investigate the potential links between cGMP signaling, breakdown of neurovascular function, and glaucoma pathology.
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Affiliation(s)
| | | | - Lauren K. Wareham
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN 37212, USA
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34
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Chen W, Liu P, Liu D, Huang H, Feng X, Fang F, Li L, Wu J, Liu L, Solow-Cordero DE, Hu Y. Maprotiline restores ER homeostasis and rescues neurodegeneration via Histamine Receptor H1 inhibition in retinal ganglion cells. Nat Commun 2022; 13:6796. [PMID: 36357388 PMCID: PMC9649812 DOI: 10.1038/s41467-022-34682-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 11/03/2022] [Indexed: 11/12/2022] Open
Abstract
When the protein or calcium homeostasis of the endoplasmic reticulum (ER) is adversely altered, cells experience ER stress that leads to various diseases including neurodegeneration. Genetic deletion of an ER stress downstream effector, CHOP, significantly protects neuron somata and axons. Here we report that three tricyclic compounds identified through a small-scale high throughput screening using a CHOP promoter-driven luciferase cell-based assay, effectively inhibit ER stress by antagonizing their common target, histamine receptor H1 (HRH1). We further demonstrated that systemic administration of one of these compounds, maprotiline, or CRISPR-mediated retinal ganglion cell (RGC)-specific HRH1 inhibition, delivers considerable neuroprotection of both RGC somata and axons and preservation of visual function in two mouse optic neuropathy models. Finally, we determine that maprotiline restores ER homeostasis by inhibiting HRH1-mediated Ca2+ release from ER. In this work we establish maprotiline as a candidate neuroprotectant and HRH1 as a potential therapeutic target for glaucoma.
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Affiliation(s)
- Wei Chen
- grid.168010.e0000000419368956Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304 USA ,grid.8547.e0000 0001 0125 2443Present Address: Multiscale Research Institute of Complex Systems, Fudan University, Shanghai, 201203 China
| | - Pingting Liu
- grid.168010.e0000000419368956Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304 USA
| | - Dong Liu
- grid.168010.e0000000419368956Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304 USA
| | - Haoliang Huang
- grid.168010.e0000000419368956Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304 USA
| | - Xue Feng
- grid.168010.e0000000419368956Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304 USA
| | - Fang Fang
- grid.168010.e0000000419368956Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304 USA ,grid.452708.c0000 0004 1803 0208Present Address: Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, 410011 China
| | - Liang Li
- grid.168010.e0000000419368956Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304 USA
| | - Jian Wu
- grid.168010.e0000000419368956Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304 USA ,grid.414373.60000 0004 1758 1243Present Address: Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730 China
| | - Liang Liu
- grid.168010.e0000000419368956Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304 USA
| | - David E. Solow-Cordero
- grid.168010.e0000000419368956High-Throughput Bioscience Center, Stanford University School of Medicine, Palo Alto, CA 94305 USA
| | - Yang Hu
- grid.168010.e0000000419368956Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304 USA
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Croteau LP, Risner ML, Wareham LK, McGrady NR, Chamling X, Zack DJ, Calkins DJ. Ex Vivo Integration of Human Stem Retinal Ganglion Cells into the Mouse Retina. Cells 2022; 11:cells11203241. [PMID: 36291110 PMCID: PMC9600680 DOI: 10.3390/cells11203241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 10/04/2022] [Accepted: 10/13/2022] [Indexed: 11/16/2022] Open
Abstract
Cell replacement therapies may be key in achieving functional recovery in neurodegenerative optic neuropathies diseases such as glaucoma. One strategy that holds promise in this regard is the use of human embryonic stem cell and induced pluripotent stem-derived retinal ganglion cells (hRGCs). Previous hRGC transplantation studies have shown modest success. This is in part due to the low survival and integration of the transplanted cells in the host retina. The field is further challenged by mixed assays and outcome measurements that probe and determine transplantation success. Thefore, we have devised a transplantation assay involving hRGCs and mouse retina explants that bypasses physical barriers imposed by retinal membranes. We show that hRGC neurites and somas are capable of invading mouse explants with a subset of hRGC neurites being guided by mouse RGC axons. Neonatal mouse retina explants, and to a lesser extent, adult explants, promote hRGC integrity and neurite outgrowth. Using this assay, we tested whether suppmenting cultures with brain derived neurotrophic factor (BDNF) and the adenylate cyclase activator, forskolin, enhances hRGC neurite integration, neurite outgrowth, and integrity. We show that supplementing cultures with a combination BDNF and forskolin strongly favors hRGC integrity, increasing neurite outgrowth and complexity as well as the invasion of mouse explants. The transplantation assay presented here is a practical tool for investigating strategies for testing and optimizing the integration of donor cells into host tissues.
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Affiliation(s)
- Louis-Philippe Croteau
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Michael L. Risner
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Lauren K. Wareham
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Nolan R. McGrady
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Xitiz Chamling
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Donald J. Zack
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - David J. Calkins
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Correspondence:
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36
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Sarossy M, Crowston J, Kumar D, Weymouth A, Wu Z. Time-Frequency Analysis of ERG With Discrete Wavelet Transform and Matching Pursuits for Glaucoma. Transl Vis Sci Technol 2022; 11:19. [PMID: 36227605 PMCID: PMC9583752 DOI: 10.1167/tvst.11.10.19] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Accepted: 09/13/2022] [Indexed: 02/01/2023] Open
Abstract
Purpose To examine the performance of two time-frequency feature extraction techniques applied to electroretinograms (ERGs) for the prediction of glaucoma severity. Methods ERGs targeting the photopic negative response were obtained in 103 eyes of 55 patients with glaucoma. Features from the ERG recordings were extracted using two time-frequency extraction techniques based on the discrete wavelet transform (DWT) and the matching pursuit (MP) decomposition. Amplitude markers of the time-domain signal were also extracted. Linear and multivariate adaptive regression spline (MARS) models were fitted using combinations of these features to predict estimated retinal ganglion cell counts, a measure of glaucoma disease severity derived from standard automated perimetry and optical coherence tomography imaging. Results Predictive models using features from the time-frequency analyses-using both DWT and MP-combined with amplitude markers outperformed predictive models using the markers alone with linear (P = 0.001) and MARS (P ≤ 0.011) models. For example, the proportions of variance (R2) explained by the MARS model using the DWT and MP features with amplitude markers were 0.53 and 0.63, respectively, compared to 0.34 for the model using the markers alone (P = 0.011 and P = 0.001, respectively). Conclusions Novel time-frequency features extracted from the photopic ERG substantially added to the prediction of glaucoma severity compared to using the time-domain amplitude markers alone. Translational Relevance Substantial information about retinal ganglion cell dysfunction exists in the time-frequency domain of ERGs that could be useful in the management of glaucoma.
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Affiliation(s)
- Marc Sarossy
- Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, Victoria, Australia
| | | | | | - Anne Weymouth
- Department of Optometry and Vision Sciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Zhichao Wu
- Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, Victoria, Australia
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia
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37
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Lai W, Huang J, Fang W, Deng S, Xie Y, Wang W, Qiao T, Xu G, Wang X, Ding F. Optic nerve head: A gatekeeper for vitreous infectious insults? Front Immunol 2022; 13:987771. [PMID: 36203577 PMCID: PMC9531234 DOI: 10.3389/fimmu.2022.987771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 08/31/2022] [Indexed: 11/19/2022] Open
Abstract
The axons of retinal ganglion cells (RGCs) pass through the optic nerve head (ONH) and form the optic nerve (ON). The ONH serves as an anatomical interface between the vitreous cavity and subarachnoid space. After inducing acute neuroinflammation by intravitreal injection of lipopolysaccharides (LPS), we observed inflammatory activation in the retina, but detect no signs of inflammation in the posterior ON or infiltration of inflammatory cells in the ONH. Therefore, we hypothesized that the ONH functions as a barrier to vitreous inflammation. Using transmission electron microscopy, we identified significant increase in G-ratio in the posterior ON on day 7 post intravitreal injection (PII) of LPS compared with the phosphate buffered saline (PBS) group. Moreover, using confocal imaging of ex vivo tissue extracted from Aldh1L1-eGFP reporter mice, we observed that the ONH astrocytes altered their spatial orientation by elongating their morphology along the axonal axis of RGCs in LPS- versus PBS-treated eyes; this was quantified by the ratio of longitudinal (DL) and transverse (DT) diameter of astrocytes and the proportion of longitudinally locating astrocytes. Supportive evidences were further provided by transmission electron microscopic imaging in rat ONH. We further conducted RNA sequencing of ONH on day 1 PII and found LPS induced clear upregulation of immune and inflammatory pathways. Furthermore, gene set enrichment analysis revealed that astrocyte and microglia contributed prominently to the transcriptomic alterations in ONH. Here, we report that the vitreous infectious insults induce morphological changes of ONH astrocytes and transcriptomic alterations in the ONH. Glial responses in the ONH may defend against vitreous infectious insults and serve as a barrier to inflammation for the central nervous system.
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Affiliation(s)
- Wenwen Lai
- Department of Pharmacology, School of Basic Medical Sciences; Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Fudan University, Shanghai, China
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jie Huang
- Department of Pharmacology, School of Basic Medical Sciences; Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Fudan University, Shanghai, China
- Department of Ophthalmology, Eye, Ear, Nose and Throat Hospital; State Key Laboratory of Medical Neurobiology and Ministry of Education Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Wangyi Fang
- Department of Ophthalmology, Shanghai Children’s Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Saiyue Deng
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yi Xie
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wei Wang
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Tong Qiao
- Department of Ophthalmology, Shanghai Children’s Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Gezhi Xu
- Department of Pharmacology, School of Basic Medical Sciences; Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Fudan University, Shanghai, China
- Department of Ophthalmology, Eye, Ear, Nose and Throat Hospital; State Key Laboratory of Medical Neurobiology and Ministry of Education Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Xiaowei Wang
- Department of Ophthalmology, University of California San Francisco, San Francisco, CA, United States
- *Correspondence: Fengfei Ding, ; Xiaowei Wang,
| | - Fengfei Ding
- Department of Pharmacology, School of Basic Medical Sciences; Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Fudan University, Shanghai, China
- Department of Ophthalmology, Eye, Ear, Nose and Throat Hospital; State Key Laboratory of Medical Neurobiology and Ministry of Education Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
- *Correspondence: Fengfei Ding, ; Xiaowei Wang,
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Esteban-Linares A, Wareham LK, Walmsley TS, Holden JM, Fitzgerald ML, Pan Z, Xu YQ, Li D. Dynamic Observation of Retinal Response to Pressure Elevation in a Microfluidic Chamber. Anal Chem 2022; 94:12297-12304. [PMID: 36018813 PMCID: PMC10519618 DOI: 10.1021/acs.analchem.1c05652] [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] [Indexed: 11/29/2022]
Abstract
Dynamic observation of cell and tissue responses to elevated pressure could help our understanding of important physiological and pathological processes related to pressure-induced injury. Here, we report on a microfluidic platform capable of maintaining a wide range of stable operating pressures (30 to 200 mmHg) while using a low flowrate (2-14 μL/h) to limit shear stress. This is achieved by forcing flow through a porous resistance matrix composed of agarose gel downstream of a microfluidic chamber. The flow characteristics were investigated and the permeabilities of the agarose with four different concentrations were extracted, agreeing well with results found in the literature. To demonstrate the capability of the device, we measured the change in intracellular Ca2+ levels of retinal ganglion cells in whole mouse retina in response to pressure. The onset of enhanced pressure results in, on average, an immediate 119.16% increase in the intracellular Ca2+ levels of retinal ganglion cells. The demonstrated microfluidic platform could be widely used to probe cell and tissue responses to elevated pressure.
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Affiliation(s)
| | - Lauren K. Wareham
- Vanderbilt Eye Institute, Vanderbilt Medical Center, Nashville, TN, 37232, USA
| | - Thayer S. Walmsley
- Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Joseph M. Holden
- Vanderbilt Eye Institute, Vanderbilt Medical Center, Nashville, TN, 37232, USA
| | - Matthew L. Fitzgerald
- Department of Mechanical Engineering, Vanderbilt University, Nashville, TN, 37235, USA
| | - Zhiliang Pan
- Department of Mechanical Engineering, Vanderbilt University, Nashville, TN, 37235, USA
| | - Ya-Qiong Xu
- Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, TN 37235, USA
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, 37235, USA
| | - Deyu Li
- Department of Mechanical Engineering, Vanderbilt University, Nashville, TN, 37235, USA
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Li L, Fang F, Feng X, Zhuang P, Huang H, Liu P, Liu L, Xu AZ, Qi LS, Cong L, Hu Y. Single-cell transcriptome analysis of regenerating RGCs reveals potent glaucoma neural repair genes. Neuron 2022; 110:2646-2663.e6. [PMID: 35952672 PMCID: PMC9391304 DOI: 10.1016/j.neuron.2022.06.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 06/05/2022] [Accepted: 06/24/2022] [Indexed: 12/17/2022]
Abstract
Axon regeneration holds great promise for neural repair of CNS axonopathies, including glaucoma. Pten deletion in retinal ganglion cells (RGCs) promotes potent optic nerve regeneration, but only a small population of Pten-null RGCs are actually regenerating RGCs (regRGCs); most surviving RGCs (surRGCs) remain non-regenerative. Here, we developed a strategy to specifically label and purify regRGCs and surRGCs, respectively, from the same Pten-deletion mice after optic nerve crush, in which they differ only in their regeneration capability. Smart-Seq2 single-cell transcriptome analysis revealed novel regeneration-associated genes that significantly promote axon regeneration. The most potent of these, Anxa2, acts synergistically with its ligand tPA in Pten-deletion-induced axon regeneration. Anxa2, its downstream effector ILK, and Mpp1 dramatically protect RGC somata and axons and preserve visual function in a clinically relevant model of glaucoma, demonstrating the exciting potential of this innovative strategy to identify novel effective neural repair candidates.
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Affiliation(s)
- Liang Li
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Fang Fang
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA 94304, USA; Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha 410011, China
| | - Xue Feng
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Pei Zhuang
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Haoliang Huang
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Pingting Liu
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Liang Liu
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Adam Z Xu
- Saratoga High School, Saratoga, CA 95070, USA
| | - Lei S Qi
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA; Stanford ChEM-H Institute, Stanford University, Stanford, CA 94305, USA
| | - Le Cong
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Wu Tsai Neuroscience Institute, Stanford University, Stanford, CA 94305, USA
| | - Yang Hu
- Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute at Stanford University School of Medicine, Palo Alto, CA 94304, USA.
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40
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Beirowski B. Emerging evidence for compromised axonal bioenergetics and axoglial metabolic coupling as drivers of neurodegeneration. Neurobiol Dis 2022; 170:105751. [PMID: 35569720 DOI: 10.1016/j.nbd.2022.105751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 04/20/2022] [Accepted: 05/09/2022] [Indexed: 10/18/2022] Open
Abstract
Impaired bioenergetic capacity of the nervous system is thought to contribute to the pathogenesis of many neurodegenerative diseases (NDD). Since neuronal synapses are believed to be the major energy consumers in the nervous system, synaptic derangements resulting from energy deficits have been suggested to play a central role for the development of many of these disorders. However, long axons constitute the largest compartment of the neuronal network, require large amounts of energy, are metabolically and structurally highly vulnerable, and undergo early injurious stresses in many NDD. These stresses likely impose additional energy demands for continuous adaptations and repair processes, and may eventually overwhelm axonal maintenance mechanisms. Indeed, pathological axon degeneration (pAxD) is now recognized as an etiological focus in a wide array of NDD associated with bioenergetic abnormalities. In this paper I first discuss the recognition that a simple experimental model for pAxD is regulated by an auto-destruction program that exhausts distressed axons energetically. Provision of the energy substrate pyruvate robustly counteracts this axonal breakdown. Importantly, energy decline in axons is not only a consequence but also an initiator of this program. This opens the intriguing possibility that axon dysfunction and pAxD can be suppressed by preemptively energizing distressed axons. Second, I focus on the emerging concept that axons communicate energetically with their flanking glia. This axoglial metabolic coupling can help offset the axonal energy decline that activates the pAxD program but also jeopardize axon integrity as a result of perturbed glial metabolism. Third, I present compelling evidence that abnormal axonal energetics and compromised axoglial metabolic coupling accompany the activation of the pAxD auto-destruction pathway in models of glaucoma, a widespread neurodegenerative condition with pathogenic overlap to other common NDD. In conclusion, I propose a novel conceptual framework suggesting that therapeutic interventions focused on bioenergetic support of the nervous system should also address axons and their metabolic interactions with glia.
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Affiliation(s)
- Bogdan Beirowski
- Institute for Myelin and Glia Exploration, New York State Center of Excellence in Bioinformatics & Life Sciences (CBLS), University at Buffalo, Buffalo, NY 14203, USA; Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14214, USA.
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41
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Lee PY, Zhao D, Wong VHY, Chrysostomou V, Crowston JG, Bui BV. The Effect of Aging on Retinal Function and Retinal Ganglion Cell Morphology Following Intraocular Pressure Elevation. Front Aging Neurosci 2022; 14:859265. [PMID: 35645783 PMCID: PMC9133539 DOI: 10.3389/fnagi.2022.859265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 04/04/2022] [Indexed: 11/13/2022] Open
Abstract
Aging and elevated intraocular pressure (IOP) are two major risk factors for glaucomatous optic neuropathy; a condition characterized by the selective, progressive injury, and subsequent loss of retinal ganglion cells (RGCs). We examined how age modified the capacity for RGCs to functionally recover following a reproducible IOP elevation (50 mmHg for 30 min). We found that RGC functional recovery (measured using electroretinography) was complete by 7 days in 3-month-old mice but was delayed in 12-month-old mice until 14 days. At the 7-day recovery endpoint when RGC function had recovered in young but not older eyes, we examined RGC structural responses to IOP-related stress by analyzing RGC dendritic morphology. ON-RGC cell volume was attenuated following IOP elevation in both young and older mice. We also found that following IOP elevation OFF-RGC dendritic morphology became less complex per cell volume in young mice, an effect that was not observed in older eyes. Our data suggest that adaptations in OFF-RGCs in young eyes were associated with better functional recovery 7 days after IOP elevation. Loss of RGC cellular adaptations may account for delayed functional recovery in older eyes.
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Affiliation(s)
- Pei Ying Lee
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Da Zhao
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Vickie H. Y. Wong
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Vicki Chrysostomou
- Singapore Eye Research Institute, Singapore, Singapore,Duke-NUS Medical School, Singapore, Singapore
| | - Jonathan G. Crowston
- Singapore Eye Research Institute, Singapore, Singapore,Duke-NUS Medical School, Singapore, Singapore
| | - Bang V. Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia,*Correspondence: Bang V. Bui,
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Fang F, Zhuang P, Feng X, Liu P, Liu D, Huang H, Li L, Chen W, Liu L, Sun Y, Jiang H, Ye J, Hu Y. NMNAT2 is downregulated in glaucomatous RGCs, and RGC-specific gene therapy rescues neurodegeneration and visual function. Mol Ther 2022; 30:1421-1431. [PMID: 35114390 PMCID: PMC9077370 DOI: 10.1016/j.ymthe.2022.01.035] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 12/17/2021] [Accepted: 01/27/2022] [Indexed: 11/19/2022] Open
Abstract
The lack of neuroprotective treatments for retinal ganglion cells (RGCs) and optic nerve (ON) is a central challenge for glaucoma management. Emerging evidence suggests that redox factor NAD+ decline is a hallmark of aging and neurodegenerative diseases. Supplementation with NAD+ precursors and overexpression of NMNAT1, the key enzyme in the NAD+ biosynthetic process, have significant neuroprotective effects. We first profile the translatomes of RGCs in naive mice and mice with silicone oil-induced ocular hypertension (SOHU)/glaucoma by RiboTag mRNA sequencing. Intriguingly, only NMNAT2, but not NMNAT1 or NMNAT3, is significantly decreased in SOHU glaucomatous RGCs, which we confirm by in situ hybridization. We next demonstrate that AAV2 intravitreal injection-mediated overexpression of long half-life NMNAT2 mutant driven by RGC-specific mouse γ-synuclein (mSncg) promoter restores decreased NAD+ levels in glaucomatous RGCs and ONs. Moreover, this RGC-specific gene therapy strategy delivers significant neuroprotection of both RGC soma and axon and preservation of visual function in the traumatic ON crush model and the SOHU glaucoma model. Collectively, our studies suggest that the weakening of NMNAT2 expression in glaucomatous RGCs contributes to a deleterious NAD+ decline, and that modulating RGC-intrinsic NMNAT2 levels by AAV2-mSncg vector is a promising gene therapy for glaucomatous neurodegeneration.
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Affiliation(s)
- Fang Fang
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA; Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha 410011, China
| | - Pei Zhuang
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Xue Feng
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Pingting Liu
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Dong Liu
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Haoliang Huang
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Liang Li
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Wei Chen
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Liang Liu
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Yang Sun
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Haowen Jiang
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Jiangbin Ye
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Yang Hu
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA.
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Wareham LK, Liddelow SA, Temple S, Benowitz LI, Di Polo A, Wellington C, Goldberg JL, He Z, Duan X, Bu G, Davis AA, Shekhar K, Torre AL, Chan DC, Canto-Soler MV, Flanagan JG, Subramanian P, Rossi S, Brunner T, Bovenkamp DE, Calkins DJ. Solving neurodegeneration: common mechanisms and strategies for new treatments. Mol Neurodegener 2022; 17:23. [PMID: 35313950 PMCID: PMC8935795 DOI: 10.1186/s13024-022-00524-0] [Citation(s) in RCA: 98] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 02/18/2022] [Indexed: 02/06/2023] Open
Abstract
Across neurodegenerative diseases, common mechanisms may reveal novel therapeutic targets based on neuronal protection, repair, or regeneration, independent of etiology or site of disease pathology. To address these mechanisms and discuss emerging treatments, in April, 2021, Glaucoma Research Foundation, BrightFocus Foundation, and the Melza M. and Frank Theodore Barr Foundation collaborated to bring together key opinion leaders and experts in the field of neurodegenerative disease for a virtual meeting titled "Solving Neurodegeneration". This "think-tank" style meeting focused on uncovering common mechanistic roots of neurodegenerative disease and promising targets for new treatments, catalyzed by the goal of finding new treatments for glaucoma, the world's leading cause of irreversible blindness and the common interest of the three hosting foundations. Glaucoma, which causes vision loss through degeneration of the optic nerve, likely shares early cellular and molecular events with other neurodegenerative diseases of the central nervous system. Here we discuss major areas of mechanistic overlap between neurodegenerative diseases of the central nervous system: neuroinflammation, bioenergetics and metabolism, genetic contributions, and neurovascular interactions. We summarize important discussion points with emphasis on the research areas that are most innovative and promising in the treatment of neurodegeneration yet require further development. The research that is highlighted provides unique opportunities for collaboration that will lead to efforts in preventing neurodegeneration and ultimately vision loss.
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Affiliation(s)
- Lauren K Wareham
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Shane A Liddelow
- Neuroscience Institute, NYU Grossman School of Medicine, New York, NY, USA
| | - Sally Temple
- Neural Stem Cell Institute, NY, 12144, Rensselaer, USA
| | - Larry I Benowitz
- Department of Neurosurgery and F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Adriana Di Polo
- Department of Neuroscience, University of Montreal, Montreal, QC, Canada
| | - Cheryl Wellington
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Jeffrey L Goldberg
- Spencer Center for Vision Research, Byers Eye Institute, Stanford University, CA, Palo Alto, USA
| | - Zhigang He
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, MA, Boston, USA
| | - Xin Duan
- Department of Ophthalmology, University of California San Francisco, San Francisco, CA, USA
| | - Guojun Bu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA
| | - Albert A Davis
- Department of Neurology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Karthik Shekhar
- Department of Chemical and Biomolecular Engineering and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, USA
| | - Anna La Torre
- Department of Cell Biology and Human Anatomy, University of California Davis, Davis, CA, USA
| | - David C Chan
- Division of Biology and Biological Engineering, California Institute of Technology, CA, 91125, Pasadena, USA
| | - M Valeria Canto-Soler
- CellSight Ocular Stem Cell and Regeneration Research Program, Department of Ophthalmology, Sue Anschutz-Rodgers Eye Center, University of Colorado, Aurora, CO, USA
| | - John G Flanagan
- Herbert Wertheim School of Optometry and Vision Science, University of California Berkeley, Berkeley, CA, USA
| | | | | | | | | | - David J Calkins
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, USA.
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Ribeiro M, McGrady NR, Baratta RO, Del Buono BJ, Schlumpf E, Calkins DJ. Intraocular Delivery of a Collagen Mimetic Peptide Repairs Retinal Ganglion Cell Axons in Chronic and Acute Injury Models. Int J Mol Sci 2022; 23:ijms23062911. [PMID: 35328332 PMCID: PMC8949359 DOI: 10.3390/ijms23062911] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/01/2022] [Accepted: 03/02/2022] [Indexed: 01/05/2023] Open
Abstract
Vision loss through the degeneration of retinal ganglion cell (RGC) axons occurs in both chronic and acute conditions that target the optic nerve. These include glaucoma, in which sensitivity to intraocular pressure (IOP) causes early RGC axonal dysfunction, and optic nerve trauma, which causes rapid axon degeneration from the site of injury. In each case, degeneration is irreversible, necessitating new therapeutics that protect, repair, and regenerate RGC axons. Recently, we demonstrated the reparative capacity of using collagen mimetic peptides (CMPs) to heal fragmented collagen in the neuronal extracellular milieu. This was an important step in the development of neuronal-based therapies since neurodegeneration involves matrix metalloproteinase (MMP)-mediated remodeling of the collagen-rich environment in which neurons and their axons exist. We found that intraocular delivery of a CMP comprising single-strand fractions of triple helix human type I collagen prevented early RGC axon dysfunction in an inducible glaucoma model. Additionally, CMPs also promoted neurite outgrowth from dorsal root ganglia, challenged in vitro by partial digestion of collagen. Here, we compared the ability of a CMP sequence to protect RGC axons in both inducible glaucoma and optic nerve crush. A three-week +40% elevation in IOP caused a 67% degradation in anterograde transport to the superior colliculus, the primary retinal projection target in rodents. We found that a single intravitreal injection of CMP during the period of IOP elevation significantly reduced this degradation. The same CMP delivered shortly after optic nerve crush promoted significant axonal recovery during the two-week period following injury. Together, these findings support a novel protective and reparative role for the use of CMPs in both chronic and acute conditions affecting the survival of RGC axons in the optic projection to the brain.
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Affiliation(s)
- Marcio Ribeiro
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, AA7103 MCN/VUIIS, 1161 21st Ave. S., Nashville, TN 37232, USA; (M.R.); (N.R.M.)
| | - Nolan R. McGrady
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, AA7103 MCN/VUIIS, 1161 21st Ave. S., Nashville, TN 37232, USA; (M.R.); (N.R.M.)
| | - Robert O. Baratta
- Stuart Therapeutics, Inc., 411 SE Osceola St., Suite 203, Stuart, FL 34994, USA; (R.O.B.); (B.J.D.B.); (E.S.)
| | - Brian J. Del Buono
- Stuart Therapeutics, Inc., 411 SE Osceola St., Suite 203, Stuart, FL 34994, USA; (R.O.B.); (B.J.D.B.); (E.S.)
| | - Eric Schlumpf
- Stuart Therapeutics, Inc., 411 SE Osceola St., Suite 203, Stuart, FL 34994, USA; (R.O.B.); (B.J.D.B.); (E.S.)
| | - David J. Calkins
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, AA7103 MCN/VUIIS, 1161 21st Ave. S., Nashville, TN 37232, USA; (M.R.); (N.R.M.)
- Correspondence: ; Tel.: +1-(615)-936-1424; Fax: +1-(615)-936-6410
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Risner ML, Pasini S, McGrady NR, Calkins DJ. Bax Contributes to Retinal Ganglion Cell Dendritic Degeneration During Glaucoma. Mol Neurobiol 2022; 59:1366-1380. [PMID: 34984584 PMCID: PMC8882107 DOI: 10.1007/s12035-021-02675-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 11/30/2021] [Indexed: 12/14/2022]
Abstract
The BCL-2 (B-cell lymphoma-2) family of proteins contributes to mitochondrial-based apoptosis in models of neurodegeneration, including glaucomatous optic neuropathy (glaucoma), which degrades the retinal ganglion cell (RGC) axonal projection to the visual brain. Glaucoma is commonly associated with increased sensitivity to intraocular pressure (IOP) and involves a proximal program that leads to RGC dendritic pruning and a distal program that underlies axonopathy in the optic projection. While genetic deletion of the Bcl2-associated X protein (Bax-/-) prolongs RGC body survival in models of glaucoma and optic nerve trauma, axonopathy persists, thus raising the question of whether dendrites and the RGC light response are protected. Here, we used an inducible model of glaucoma in Bax-/- mice to determine if Bax contributes to RGC dendritic degeneration. We performed whole-cell recordings and dye filling in RGCs signaling light onset (αON-Sustained) and offset (αOFF-Sustained). We recovered RGC dendritic morphologies by confocal microscopy and analyzed dendritic arbor complexity and size. Additionally, we assessed RGC axon function by measuring anterograde axon transport of cholera toxin subunit B to the superior colliculus and behavioral spatial frequency threshold (i.e., spatial acuity). We found 1 month of IOP elevation did not cause significant RGC death in either WT or Bax-/- retinas. However, IOP elevation reduced dendritic arbor complexity of WT αON-Sustained and αOFF-Sustained RGCs. In the absence of Bax, αON- and αOFF-Sustained RGC dendritic arbors remained intact following IOP elevation. In addition to dendrites, neuroprotection by Bax-/- generalized to αON-and αOFF-Sustained RGC light- and current-evoked responses. Both anterograde axon transport and spatial acuity declined during IOP elevation in WT and Bax-/- mice. Collectively, our results indicate Bax contributes to RGC dendritic degeneration and distinguishes the proximal and distal neurodegenerative programs involved during the progression of glaucoma.
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Affiliation(s)
- Michael L Risner
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, AA7103 MCN/VUIIS, 1161 21st Ave. S., Nashville, TN, 37232, USA
| | - Silvia Pasini
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, AA7103 MCN/VUIIS, 1161 21st Ave. S., Nashville, TN, 37232, USA
| | - Nolan R McGrady
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, AA7103 MCN/VUIIS, 1161 21st Ave. S., Nashville, TN, 37232, USA
| | - David J Calkins
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, AA7103 MCN/VUIIS, 1161 21st Ave. S., Nashville, TN, 37232, USA.
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Sarossy M, Crowston J, Kumar D, Weymouth A, Wu Z. Prediction of glaucoma severity using parameters from the electroretinogram. Sci Rep 2021; 11:23886. [PMID: 34903831 PMCID: PMC8668922 DOI: 10.1038/s41598-021-03421-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Accepted: 11/29/2021] [Indexed: 11/17/2022] Open
Abstract
Glaucoma is an optic neuropathy that results in the progressive loss of retinal ganglion cells (RGCs), which are known to exhibit functional changes prior to cell loss. The electroretinogram (ERG) is a method that enables an objective assessment of retinal function, and the photopic negative response (PhNR) has conventionally been used to provide a measure of RGC function. This study sought to examine if additional parameters from the ERG (amplitudes of the a-, b-, i-wave, as well the trough between the b- and i-wave), a multivariate adaptive regression splines (MARS; a non-linear) model and achromatic stimuli could better predict glaucoma severity in 103 eyes of 55 individuals with glaucoma. Glaucoma severity was determined using standard automated perimetry and optical coherence tomography imaging. ERGs targeting the PhNR were recorded with a chromatic (red-on-blue) and achromatic (white-on-white) stimulus with the same luminance. Linear and MARS models were fitted to predict glaucoma severity using the PhNR only or all ERG markers, derived from chromatic and achromatic stimuli. Use of all ERG markers predicted glaucoma severity significantly better than the PhNR alone (P ≤ 0.02), and the MARS performed better than linear models when using all markers (P = 0.01), but there was no significant difference between the achromatic and chromatic stimulus models. This study shows that there is more information present in the photopic ERG beyond the conventional PhNR measure in characterizing RGC function.
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Affiliation(s)
- Marc Sarossy
- Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, VIC, Australia.
| | | | | | - Anne Weymouth
- Department of Optometry and Vision Sciences, The University of Melbourne, Melbourne, Australia
| | - Zhichao Wu
- Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, VIC, Australia
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
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Calkins DJ, Yu-Wai-Man P, Newman NJ, Taiel M, Singh P, Chalmey C, Rogue A, Carelli V, Ancian P, Sahel JA. Biodistribution of intravitreal lenadogene nolparvovec gene therapy in nonhuman primates. Mol Ther Methods Clin Dev 2021; 23:307-318. [PMID: 34729378 PMCID: PMC8526752 DOI: 10.1016/j.omtm.2021.09.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 09/24/2021] [Indexed: 11/25/2022]
Abstract
Lenadogene nolparvovec (Lumevoq) gene therapy was developed to treat Leber hereditary optic neuropathy (LHON) caused by the m.11778G > A in MT-ND4 that affects complex I of the mitochondrial respiratory chain. Lenadogene nolparvovec is a replication-defective, single-stranded DNA recombinant adeno-associated virus vector 2 serotype 2, containing a codon-optimized complementary DNA encoding the human wild-type MT-ND4 subunit protein. Lenadogene nolparvovec was administered by unilateral intravitreal injection in MT-ND4 LHON patients in two randomized, double-masked, and sham-controlled phase III clinical trials (REVERSE and RESCUE), resulting in bilateral improvement of visual acuity. These and other earlier results suggest that lenadogene nolparvovec may travel from the treated to the untreated eye. To investigate this possibility further, lenadogene nolparvovec was unilaterally injected into the vitreous body of the right eye of healthy, nonhuman primates. Viral vector DNA was quantifiable in all eye and optic nerve tissues of the injected eye and was detected at lower levels in some tissues of the contralateral, noninjected eye, and optic projections, at 3 and 6 months after injection. The results suggest that lenadogene nolparvovec transfers from the injected to the noninjected eye, thus providing a potential explanation for the bilateral improvement of visual function observed in the LHON patients.
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Affiliation(s)
- David J. Calkins
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, TN 37232, USA
| | - Patrick Yu-Wai-Man
- Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
- Cambridge Eye Unit, Addenbrooke’s Hospital, Cambridge University Hospitals, Cambridge, UK
- Moorfields Eye Hospital, London, UK
- UCL Institute of Ophthalmology, University College London, London, UK
| | - Nancy J. Newman
- Departments of Ophthalmology, Neurology, and Neurological Surgery, Emory University School of Medicine, Atlanta, GA, USA
| | - Magali Taiel
- GenSight Biologics, 74 rue du Faubourg Saint Antoine, 75012 Paris, France
| | | | | | | | - Valerio Carelli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica, Neurologica, Bologna, Italy
- Unit of Neurology, Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | | | - José A. Sahel
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
- Fondation Ophtalmologique A. de Rothschild, Paris, France
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- CHNO des Quinze-Vingts, Institut Hospitalo-Universitaire FOReSIGHT, INSERM-DGOS CIC, Paris, France
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McGrady NR, Pasini S, Baratta RO, Del Buono BJ, Schlumpf E, Calkins DJ. Restoring the Extracellular Matrix: A Neuroprotective Role for Collagen Mimetic Peptides in Experimental Glaucoma. Front Pharmacol 2021; 12:764709. [PMID: 34795592 PMCID: PMC8592892 DOI: 10.3389/fphar.2021.764709] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/19/2021] [Indexed: 11/24/2022] Open
Abstract
Optic neuropathies are a major cause of visual disabilities worldwide, causing irreversible vision loss through the degeneration of retinal ganglion cell (RGC) axons, which comprise the optic nerve. Chief among these is glaucoma, in which sensitivity to intraocular pressure (IOP) leads to RGC axon dysfunction followed by outright degeneration of the optic projection. Current treatments focus entirely on lowering IOP through topical hypotensive drugs, surgery to facilitate aqueous fluid outflow, or both. Despite this investment in time and resources, many patients continue to lose vision, underscoring the need for new therapeutics that target neurodegeneration directly. One element of progression in glaucoma involves matrix metalloproteinase (MMP) remodeling of the collagen-rich extracellular milieu of RGC axons as they exit the retina through the optic nerve head. Thus, we investigated the ability of collagen mimetic peptides (CMPs) representing various single strand fractions of triple helix human type I collagen to protect RGC axons in an inducible model of glaucoma. First, using dorsal root ganglia maintained in vitro on human type I collagen, we found that multiple CMPs significantly promote neurite outgrowth (+35%) compared to vehicle following MMP-induced fragmentation of the α1(I) and α2(I) chains. We then applied CMP to adult mouse eyes in vivo following microbead occlusion to elevate IOP and determined its influence on anterograde axon transport to the superior colliculus, the primary RGC projection target in rodents. In glaucoma models, sensitivity to IOP causes early degradation in axon function, including anterograde transport from retina to central brain targets. We found that CMP treatment rescued anterograde transport following a 3-week +50% elevation in IOP. These results suggest that CMPs generally may represent a novel therapeutic to supplement existing treatments or as a neuroprotective option for patients who do not respond to IOP-lowering regimens.
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Affiliation(s)
- Nolan R McGrady
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Silvia Pasini
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | | | | | - Eric Schlumpf
- Stuart Therapeutics, Inc., Stuart, FL, United States
| | - David J Calkins
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
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Vernazza S, Tirendi S, Passalacqua M, Piacente F, Scarfì S, Oddone F, Bassi AM. An Innovative In Vitro Open-Angle Glaucoma Model (IVOM) Shows Changes Induced by Increased Ocular Pressure and Oxidative Stress. Int J Mol Sci 2021; 22:ijms222212129. [PMID: 34830007 PMCID: PMC8622817 DOI: 10.3390/ijms222212129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/26/2021] [Accepted: 11/08/2021] [Indexed: 02/07/2023] Open
Abstract
Primary Open-Angle Glaucoma (POAG) is a neurodegenerative disease, and its clinical outcomes lead to visual field constriction and blindness. POAG's etiology is very complex and its pathogenesis is mainly explained through both mechanical and vascular theories. The trabecular meshwork (TM), the most sensitive tissue of the eye anterior segment to oxidative stress (OS), is the main tissue involved in early-stage POAG, characterized by an increase in pressure. Preclinical assessments of neuroprotective drugs on animal models have not always shown correspondence with human clinical studies. In addition, intra-ocular pressure management after a glaucoma diagnosis does not always prevent blindness. Recently, we have been developing an innovative in vitro 3Dadvanced human trabecular cell model on a millifluidicplatform as a tool to improve glaucoma studies. Herein, we analyze the effects of prolonged increased pressure alone and, in association with OS, on such in vitro platform. Moreover, we verify whethersuch damaged TM triggers apoptosis on neuron-like cells. The preliminary results show that TM cells are less sensitive to pressure elevation than OS, and OS-damaging effects were worsened by the pressure increase. The stressed TM releases harmful signals, which increase apoptosis stimuli on neuron-like cells, suggesting its pivotal role in the glaucoma cascade.
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Affiliation(s)
- Stefania Vernazza
- Department of Experimental Medicine (DIMES), University of Genoa, 16132 Genoa, Italy; (S.V.); (S.T.); (F.P.); (A.M.B.)
| | - Sara Tirendi
- Department of Experimental Medicine (DIMES), University of Genoa, 16132 Genoa, Italy; (S.V.); (S.T.); (F.P.); (A.M.B.)
- Inter-University Center for the Promotion of the 3Rs Principles in Teaching & Research (Centro 3R), 56122 Pisa, Italy;
| | - Mario Passalacqua
- Department of Experimental Medicine (DIMES), University of Genoa, 16132 Genoa, Italy; (S.V.); (S.T.); (F.P.); (A.M.B.)
- Inter-University Center for the Promotion of the 3Rs Principles in Teaching & Research (Centro 3R), 56122 Pisa, Italy;
- Correspondence:
| | - Francesco Piacente
- Department of Experimental Medicine (DIMES), University of Genoa, 16132 Genoa, Italy; (S.V.); (S.T.); (F.P.); (A.M.B.)
| | - Sonia Scarfì
- Inter-University Center for the Promotion of the 3Rs Principles in Teaching & Research (Centro 3R), 56122 Pisa, Italy;
- Department of Earth, Environmental and Life Sciences (DISTAV), University of Genoa, 16132 Genoa, Italy
| | | | - Anna Maria Bassi
- Department of Experimental Medicine (DIMES), University of Genoa, 16132 Genoa, Italy; (S.V.); (S.T.); (F.P.); (A.M.B.)
- Inter-University Center for the Promotion of the 3Rs Principles in Teaching & Research (Centro 3R), 56122 Pisa, Italy;
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Toychiev AH, Batsuuri K, Srinivas M. Gap Junctional Coupling Between Retinal Astrocytes Exacerbates Neuronal Damage in Ischemia-Reperfusion Injury. Invest Ophthalmol Vis Sci 2021; 62:27. [PMID: 34846518 PMCID: PMC8648063 DOI: 10.1167/iovs.62.14.27] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Purpose Retinal astrocytes abundantly express connexin 43 (Cx43), a transmembrane protein that forms gap junction (GJ) channels and unopposed hemichannels. While it is well established that Cx43 is upregulated in retinal injuries, it is unclear whether astrocytic Cx43 plays a role in retinal ganglion cell (RGC) loss associated with injury. Here, we investigated the effect of astrocyte-specific deletion of Cx43 (Cx43KO) and channel inhibitors on RGC loss in retinal ischemia/reperfusion (I/R) injury and assessed changes in expression and GJ channel and hemichannel function that occur in I/R injury. The effect of Cx43 deletion on neural function in the uninjured retina was also assessed. Methods Cx43 expression, astrocyte density and morphology, and RGC death in wild-type and Cx43KO mice after I/R injury were determined using immunohistochemistry and Western blotting. Visual function was assessed using ERG recordings. GJ coupling and hemichannel activity were evaluated using tracer coupling and uptake studies, respectively. Results Loss of RGCs in I/R injury was accompanied by an increase of Cx43 expression in astrocytes. Functional studies indicated that I/R injury augmented astrocytic GJ coupling but not Cx43 hemichannel activity. Importantly, deletion of astrocytic Cx43 improved neuronal survival in acute ischemia but did not affect RGC function in the absence of injury. In support, pharmacologic inhibition of GJ coupling provided neuroprotection in I/R injury. Conclusions The increase in Cx43 expression and GJ coupling during acute I/R injury exacerbates RGC loss. Inhibition of astrocytic Cx43 channels might represent a useful strategy to promote RGC survival in pathologic conditions.
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Affiliation(s)
- Abduqodir H Toychiev
- Department of Biological and Vision Sciences, SUNY College of Optometry, New York, NY, United States
| | - Khulan Batsuuri
- Department of Biological and Vision Sciences, SUNY College of Optometry, New York, NY, United States
| | - Miduturu Srinivas
- Department of Biological and Vision Sciences, SUNY College of Optometry, New York, NY, United States
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