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Soucy JR, Kriukov E, Oswald J, Phay M, Masland J, Pernstich C, Baranov P. Sustained neurotrophic factor cotreatment enhances donor and host retinal ganglion cell survival in mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.07.583961. [PMID: 38558999 PMCID: PMC10979869 DOI: 10.1101/2024.03.07.583961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Retinal ganglion cells (RGCs) lack regenerative capacity in mammals, and their degeneration in glaucoma leads to irreversible blindness. The transplantation of stem cell-derived RGCs lacks clinically relevant effect due to insufficient survival and integration of donor cells. We hypothesize that the retinal microenvironment plays a critical role in this process, and we can engineer a more acceptable setting for transplantation. Since the adult mammalian retina does not have regenerative capacity, we turned to the developing human retina to reconstruct cell-cell interactions at a single-cell level. We established a human fetal retina atlas by integrating currently available single-cell RNA sequencing datasets of human fetal retinas into a unified resource. We align RGC transcriptomes in pseudotime to map RGC developmental fate trajectories against the broader timeline of retinal development. Through this analysis, we identified brain-derived neurotrophic factor (BDNF) and glial-derived neurotrophic factor (GDNF) as key factors in RGC survival, highly expressed during fetal development but significantly reduced in adulthood despite the persistence of their receptors. To demonstrate the practical application of these findings, we show that using a slow-release formulation of BDNF and GDNF enhances RGC differentiation, survival, and function in vitro and improves RGC transplantation outcomes in a mouse model. BNDF/GDNF co-treatment not only increased survival and coverage of donor RGCs within the retina but also showed neuroprotective effects on host RGCs, preserving retinal function in a model of optic neuropathy. Altogether, our findings suggest that manipulating the retinal microenvironment with slow-release neurotrophic factors holds promise in regenerative medicine for treating glaucoma and other optic neuropathies. This approach not only improves donor cell survival and integration but also provides a neuroprotective benefit to host cells, indicating a significant advancement for glaucoma therapies.
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Han JS, Park CK, Jung KI. Retinal Neurodegeneration in an Intraocular Pressure Fluctuation Rat Model. Int J Mol Sci 2024; 25:3689. [PMID: 38612500 PMCID: PMC11011540 DOI: 10.3390/ijms25073689] [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: 02/18/2024] [Revised: 03/21/2024] [Accepted: 03/22/2024] [Indexed: 04/14/2024] Open
Abstract
Increased intraocular pressure (IOP) is the most important risk factor for glaucoma. The role of IOP fluctuation, independently from elevated IOP, has not yet been confirmed in glaucoma. We investigated the effects of IOP fluctuation itself on retinal neurodegeneration. Male rats were treated with IOP-lowering eyedrops (brinzolamide and latanoprost) on Mondays and Thursdays (in the irregular instillation group) or daily (in the regular instillation group), and saline was administered daily in the normal control group for 8 weeks. The IOP standard deviation was higher in the irregular instillation group than the regular instillation group or the control group. The degree of oxidative stress, which was analyzed by labeling superoxide, oxidative DNA damage, and nitrotyrosine, was increased in the irregular instillation group. Macroglial activation, expressed by glial fibrillary acidic protein in the optic nerve head and retina, was observed with the irregular instillation of IOP-lowering eyedrops. Microglial activation, as indicated by Iba-1, and the expression of TNF-α did not show a significant difference between the irregular instillation and control groups. Expression of cleaved caspase-3 was upregulated and the number of retinal ganglion cells (RGCs) was decreased in the irregular instillation group. Our findings indicate that IOP fluctuations could be induced by irregular instillation of IOP-lowering eyedrops and this could lead to the degeneration of RGCs, probably through increased oxidative stress and macrogliosis.
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Affiliation(s)
| | | | - Kyoung In Jung
- Department of Ophthalmology, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea; (J.-S.H.); (C.K.P.)
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Pitha I, Du L, Nguyen TD, Quigley H. IOP and glaucoma damage: The essential role of optic nerve head and retinal mechanosensors. Prog Retin Eye Res 2024; 99:101232. [PMID: 38110030 PMCID: PMC10960268 DOI: 10.1016/j.preteyeres.2023.101232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 12/10/2023] [Accepted: 12/11/2023] [Indexed: 12/20/2023]
Abstract
There are many unanswered questions on the relation of intraocular pressure to glaucoma development and progression. IOP itself cannot be distilled to a single, unifying value, because IOP level varies over time, differs depending on ocular location, and can be affected by method of measurement. Ultimately, IOP level creates mechanical strain that affects axonal function at the optic nerve head which causes local extracellular matrix remodeling and retinal ganglion cell death - hallmarks of glaucoma and the cause of glaucomatous vision loss. Extracellular tissue strain at the ONH and lamina cribrosa is regionally variable and differs in magnitude and location between healthy and glaucomatous eyes. The ultimate targets of IOP-induced tissue strain in glaucoma are retinal ganglion cell axons at the optic nerve head and the cells that support axonal function (astrocytes, the neurovascular unit, microglia, and fibroblasts). These cells sense tissue strain through a series of signals that originate at the cell membrane and alter cytoskeletal organization, migration, differentiation, gene transcription, and proliferation. The proteins that translate mechanical stimuli into molecular signals act as band-pass filters - sensing some stimuli while ignoring others - and cellular responses to stimuli can differ based on cell type and differentiation state. Therefore, to fully understand the IOP signals that are relevant to glaucoma, it is necessary to understand the ultimate cellular targets of IOP-induced mechanical stimuli and their ability to sense, ignore, and translate these signals into cellular actions.
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Affiliation(s)
- Ian Pitha
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Center for Nanomedicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Glaucoma Center of Excellence, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Liya Du
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Thao D Nguyen
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, MD, USA
| | - Harry Quigley
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Glaucoma Center of Excellence, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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Fernández-Albarral JA, Ramírez AI, de Hoz R, Matamoros JA, Salobrar-García E, Elvira-Hurtado L, López-Cuenca I, Sánchez-Puebla L, Salazar JJ, Ramírez JM. Glaucoma: from pathogenic mechanisms to retinal glial cell response to damage. Front Cell Neurosci 2024; 18:1354569. [PMID: 38333055 PMCID: PMC10850296 DOI: 10.3389/fncel.2024.1354569] [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: 12/12/2023] [Accepted: 01/10/2024] [Indexed: 02/10/2024] Open
Abstract
Glaucoma is a neurodegenerative disease of the retina characterized by the irreversible loss of retinal ganglion cells (RGCs) leading to visual loss. Degeneration of RGCs and loss of their axons, as well as damage and remodeling of the lamina cribrosa are the main events in the pathogenesis of glaucoma. Different molecular pathways are involved in RGC death, which are triggered and exacerbated as a consequence of a number of risk factors such as elevated intraocular pressure (IOP), age, ocular biomechanics, or low ocular perfusion pressure. Increased IOP is one of the most important risk factors associated with this pathology and the only one for which treatment is currently available, nevertheless, on many cases the progression of the disease continues, despite IOP control. Thus, the IOP elevation is not the only trigger of glaucomatous damage, showing the evidence that other factors can induce RGCs death in this pathology, would be involved in the advance of glaucomatous neurodegeneration. The underlying mechanisms driving the neurodegenerative process in glaucoma include ischemia/hypoxia, mitochondrial dysfunction, oxidative stress and neuroinflammation. In glaucoma, like as other neurodegenerative disorders, the immune system is involved and immunoregulation is conducted mainly by glial cells, microglia, astrocytes, and Müller cells. The increase in IOP produces the activation of glial cells in the retinal tissue. Chronic activation of glial cells in glaucoma may provoke a proinflammatory state at the retinal level inducing blood retinal barrier disruption and RGCs death. The modulation of the immune response in glaucoma as well as the activation of glial cells constitute an interesting new approach in the treatment of glaucoma.
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Affiliation(s)
- Jose A. Fernández-Albarral
- Ramon Castroviejo Ophthalmological Research Institute, Complutense University of Madrid (UCM), Grupo UCM 920105, IdISSC, Madrid, Spain
| | - Ana I. Ramírez
- Ramon Castroviejo Ophthalmological Research Institute, Complutense University of Madrid (UCM), Grupo UCM 920105, IdISSC, Madrid, Spain
- Department of Immunology, Ophthalmology and ENT, Faculty of Optics and Optometry, Complutense University of Madrid, Madrid, Spain
| | - Rosa de Hoz
- Ramon Castroviejo Ophthalmological Research Institute, Complutense University of Madrid (UCM), Grupo UCM 920105, IdISSC, Madrid, Spain
- Department of Immunology, Ophthalmology and ENT, Faculty of Optics and Optometry, Complutense University of Madrid, Madrid, Spain
| | - José A. Matamoros
- Ramon Castroviejo Ophthalmological Research Institute, Complutense University of Madrid (UCM), Grupo UCM 920105, IdISSC, Madrid, Spain
- Department of Immunology, Ophthalmology and ENT, Faculty of Optics and Optometry, Complutense University of Madrid, Madrid, Spain
| | - Elena Salobrar-García
- Ramon Castroviejo Ophthalmological Research Institute, Complutense University of Madrid (UCM), Grupo UCM 920105, IdISSC, Madrid, Spain
- Department of Immunology, Ophthalmology and ENT, Faculty of Optics and Optometry, Complutense University of Madrid, Madrid, Spain
| | - Lorena Elvira-Hurtado
- Ramon Castroviejo Ophthalmological Research Institute, Complutense University of Madrid (UCM), Grupo UCM 920105, IdISSC, Madrid, Spain
| | - Inés López-Cuenca
- Ramon Castroviejo Ophthalmological Research Institute, Complutense University of Madrid (UCM), Grupo UCM 920105, IdISSC, Madrid, Spain
- Department of Immunology, Ophthalmology and ENT, Faculty of Optics and Optometry, Complutense University of Madrid, Madrid, Spain
| | - Lidia Sánchez-Puebla
- Ramon Castroviejo Ophthalmological Research Institute, Complutense University of Madrid (UCM), Grupo UCM 920105, IdISSC, Madrid, Spain
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Complutense University of Madrid, Madrid, Spain
| | - Juan J. Salazar
- Ramon Castroviejo Ophthalmological Research Institute, Complutense University of Madrid (UCM), Grupo UCM 920105, IdISSC, Madrid, Spain
- Department of Immunology, Ophthalmology and ENT, Faculty of Optics and Optometry, Complutense University of Madrid, Madrid, Spain
| | - José M. Ramírez
- Ramon Castroviejo Ophthalmological Research Institute, Complutense University of Madrid (UCM), Grupo UCM 920105, IdISSC, Madrid, Spain
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Complutense University of Madrid, Madrid, Spain
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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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6
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Korneva A, Kimball EC, Johnson TV, Quillen SE, Pease ME, Quigley HA, Nguyen TD. Comparison of the Biomechanics of the Mouse Astrocytic Lamina Cribrosa Between Glaucoma and Optic Nerve Crush Models. Invest Ophthalmol Vis Sci 2023; 64:14. [PMID: 38088825 PMCID: PMC10720758 DOI: 10.1167/iovs.64.15.14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 11/14/2023] [Indexed: 12/17/2023] Open
Abstract
Purpose The strain response of the mouse astrocytic lamina (AL) to an ex vivo mechanical test was compared between two protocols: eyes that underwent sustained intraocular pressure (IOP) increase and eyes after optic nerve crush. Methods Chronic IOP elevation was induced by microbead injection or the optic nerve was crushed in mice with widespread green fluorescence. After 3 days or 6 weeks, eyes were inflation tested by a published method of two-photon fluorescence to image the AL. Digital volume correlation was used to calculate strains. Optic nerve axon damage was also evaluated. Results In the central AL but not the peripheral AL, four strains were greater in eyes at the 3-day glaucoma time point than control (P from 0.029 to 0.049, n = 8 eyes per group). Also, at this time point, five strains were greater in the central AL compared to the peripheral AL (P from 0.041 to 0.00003). At the 6-week glaucoma time point, the strains averaged across the specimen, in the central AL, and the peripheral AL were indistinguishable from the respective controls. Strains were not significantly different between controls and eyes 3 days or 6 weeks after crush (n = 8 and 16). Conclusions We found alterations in the ex vivo mechanical behavior in eyes from mice with experimental glaucoma but not in those with crushed optic nerves. The results of this study demonstrate that significant axon injury does not directly affect mechanical behavior of the astrocytic lamina.
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Affiliation(s)
- Arina Korneva
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Elizabeth C. Kimball
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Thomas V. Johnson
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Sarah E. Quillen
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Mary E. Pease
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Harry A. Quigley
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Thao D. Nguyen
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland, United States
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7
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Soucy JR, Aguzzi EA, Cho J, Gilhooley MJ, Keuthan C, Luo Z, Monavarfeshani A, Saleem MA, Wang XW, Wohlschlegel J, Baranov P, Di Polo A, Fortune B, Gokoffski KK, Goldberg JL, Guido W, Kolodkin AL, Mason CA, Ou Y, Reh TA, Ross AG, Samuels BC, Welsbie D, Zack DJ, Johnson TV. Retinal ganglion cell repopulation for vision restoration in optic neuropathy: a roadmap from the RReSTORe Consortium. Mol Neurodegener 2023; 18:64. [PMID: 37735444 PMCID: PMC10514988 DOI: 10.1186/s13024-023-00655-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 09/07/2023] [Indexed: 09/23/2023] Open
Abstract
Retinal ganglion cell (RGC) death in glaucoma and other optic neuropathies results in irreversible vision loss due to the mammalian central nervous system's limited regenerative capacity. RGC repopulation is a promising therapeutic approach to reverse vision loss from optic neuropathies if the newly introduced neurons can reestablish functional retinal and thalamic circuits. In theory, RGCs might be repopulated through the transplantation of stem cell-derived neurons or via the induction of endogenous transdifferentiation. The RGC Repopulation, Stem Cell Transplantation, and Optic Nerve Regeneration (RReSTORe) Consortium was established to address the challenges associated with the therapeutic repair of the visual pathway in optic neuropathy. In 2022, the RReSTORe Consortium initiated ongoing international collaborative discussions to advance the RGC repopulation field and has identified five critical areas of focus: (1) RGC development and differentiation, (2) Transplantation methods and models, (3) RGC survival, maturation, and host interactions, (4) Inner retinal wiring, and (5) Eye-to-brain connectivity. Here, we discuss the most pertinent questions and challenges that exist on the path to clinical translation and suggest experimental directions to propel this work going forward. Using these five subtopic discussion groups (SDGs) as a framework, we suggest multidisciplinary approaches to restore the diseased visual pathway by leveraging groundbreaking insights from developmental neuroscience, stem cell biology, molecular biology, optical imaging, animal models of optic neuropathy, immunology & immunotolerance, neuropathology & neuroprotection, materials science & biomedical engineering, and regenerative neuroscience. While significant hurdles remain, the RReSTORe Consortium's efforts provide a comprehensive roadmap for advancing the RGC repopulation field and hold potential for transformative progress in restoring vision in patients suffering from optic neuropathies.
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Affiliation(s)
- Jonathan R Soucy
- Department of Ophthalmology, Schepens Eye Research Institute of Mass. Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Erika A Aguzzi
- The Institute of Ophthalmology, University College London, London, England, UK
| | - Julie Cho
- Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Michael James Gilhooley
- The Institute of Ophthalmology, University College London, London, England, UK
- Moorfields Eye Hospital, London, England, UK
| | - Casey Keuthan
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ziming Luo
- Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Aboozar Monavarfeshani
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
- Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA
| | - Meher A Saleem
- Bascom Palmer Eye Institute, University of Miami Health System, Miami, FL, USA
| | - Xue-Wei Wang
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | | | - Petr Baranov
- Department of Ophthalmology, Schepens Eye Research Institute of Mass. Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Adriana Di Polo
- Department of Neuroscience, University of Montreal, Montreal, QC, Canada
- University of Montreal Hospital Research Centre, Montreal, QC, Canada
| | - Brad Fortune
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, OR, USA
| | - Kimberly K Gokoffski
- Department of Ophthalmology, Roski Eye Institute, University of Southern California, Los Angeles, CA, USA
| | - Jeffrey L Goldberg
- Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - William Guido
- Department of Anatomical Sciences and Neurobiology, School of Medicine, University of Louisville, Louisville, KY, USA
| | - Alex L Kolodkin
- The Solomon H Snyder, Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Carol A Mason
- Departments of Pathology and Cell Biology, Neuroscience, and Ophthalmology, College of Physicians and Surgeons, Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Yvonne Ou
- Department of Ophthalmology, University of California, San Francisco, CA, USA
| | - Thomas A Reh
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Ahmara G Ross
- Departments of Ophthalmology and Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - Brian C Samuels
- Department of Ophthalmology and Visual Sciences, Callahan Eye Hospital, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Derek Welsbie
- Shiley Eye Institute and Viterbi Family Department of Ophthalmology, University of California, San Diego, CA, USA
| | - Donald J Zack
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, 21287 MD, USA
- Departments of Neuroscience, Molecular Biology & Genetics, and Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Thomas V Johnson
- Departments of Neuroscience, Molecular Biology & Genetics, and Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Cellular & Molecular Medicine Program, Johns Hopkins University School of Medicine, Baltimore, 21287 MD, USA.
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Zhu Y, Wang R, Pappas AC, Seifert P, Savol A, Sadreyev RI, Sun D, Jakobs TC. Astrocytes in the Optic Nerve Are Heterogeneous in Their Reactivity to Glaucomatous Injury. Cells 2023; 12:2131. [PMID: 37681863 PMCID: PMC10486930 DOI: 10.3390/cells12172131] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 07/14/2023] [Accepted: 08/18/2023] [Indexed: 09/09/2023] Open
Abstract
The optic nerve head is thought to be the site of initial injury to retinal ganglion cell injury in glaucoma. In the initial segment of the optic nerve directly behind the globe, the ganglion cell axons are unmyelinated and come into direct contact to astrocytes, suggesting that astrocytes may play a role in the pathology of glaucoma. As in other parts of the CNS, optic nerve head astrocytes respond to injury by characteristic changes in cell morphology and gene expression profile. Using RNA-sequencing of glaucomatous optic nerve heads, single-cell PCR, and an in-vivo assay, we demonstrate that an up-regulation of astrocytic phagocytosis is an early event after the onset of increased intraocular pressure. We also show that astrocytes in the glial lamina of the optic nerve are apparently functionally heterogeneous. At any time, even in naïve nerves, some of the cells show signs of reactivity-process hypertrophy, high phagocytic activity, and expression of genetic markers of reactivity whereas neighboring cells apparently are inactive. A period of increased intraocular pressure moves more astrocytes towards the reactive phenotype; however, some cells remain unreactive even in glaucomatous nerves.
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Affiliation(s)
- Ying Zhu
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA
- Department of Ophthalmology, Stanford University, 1651 Page Mill Road, Palo Alto, CA 94304, USA
| | - Rui Wang
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA
- Department of Ophthalmology, The First Affiliated Hospital of Northwest University, Xi’an 710002, China
| | - Anthony C. Pappas
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA
| | - Philip Seifert
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA
| | - Andrej Savol
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Pathology, Massachusetts General Hospital and Harvard Medical School, 185 Cambridge St., Boston, MA 02114, USA
| | - Ruslan I. Sadreyev
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Pathology, Massachusetts General Hospital and Harvard Medical School, 185 Cambridge St., Boston, MA 02114, USA
| | - Daniel Sun
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA
| | - Tatjana C. Jakobs
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA
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9
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Korneva A, Kimball EC, Quillen S, Jefferys JL, Nawathe M, Ling YTT, Nguyen TD, Quigley HA. Mechanical strain in the mouse astrocytic lamina increases after exposure to recombinant trypsin. Acta Biomater 2023; 163:312-325. [PMID: 35196555 PMCID: PMC9391529 DOI: 10.1016/j.actbio.2022.02.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 01/21/2022] [Accepted: 02/16/2022] [Indexed: 11/30/2022]
Abstract
The responses of astrocytes in the optic nerve head (ONH) to mechanical and biochemical stimuli are important to understanding the degeneration of retinal ganglion cell axons in glaucoma. The ONH in glaucoma is vulnerable to stress produced by the intraocular pressure (IOP). Notably, after three days of elevated IOP in a mouse model, the junctions between the astrocytic processes and the peripapillary sclera were altered and the structural compliance of the ONH increased. In order to simulate this aspect of glaucomatous remodeling, explanted mouse eyes were treated with TrypLE, a recombinant trypsin enzyme. Treatment with TrypLE caused the periphery of the astrocytic lamina to contract radially by 0.044 ± 0.038. Transmission electron microscopy showed that TrypLE caused a separation of the end-feet of the astrocyte processes from the basement membrane at the junction with the sclera. Inflation testing after treatment with TrypLE caused an increased strain response in the astrocytic lamina compared to the strain response before treatment. The greatest increase was in the radial Green-Lagrange strain, Err = 0.028 ± 0.009, which increased by 340%. The alterations in the microstructure and in the strain response of the astrocytic lamina reported in mouse experimental glaucoma were partially reproduced by experimental treatment of mouse eyes with TrypLE. The results herein suggest that separation of junctions between the astrocyte processes and the sclera may be instrumental in increasing the structural compliance of the ONH after a period of elevated IOP. STATEMENT OF SIGNIFICANCE: Astrocytes of the optic nerve of the eye spread out from edge to edge across the optic nerve in a region referred to as the astrocytic lamina. In an experimental model of glaucoma caused by elevated eye-pressure, there is disruption of the connections between astrocytes and the edge of the astrocytic lamina. We caused a similar event in the lamina by incubating explanted mouse eyes with an enzyme. Disruption of the astrocyte connections to the edge of their tissue caused the tissue to stretch more when we increased the eye-pressure, compared to the control tissue. This work is the first on the tissue of the optic nerve to demonstrate the importance of cell connections in preventing the over-stretching of the astrocytic lamina.
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Affiliation(s)
- Arina Korneva
- Glaucoma Center of Excellence, Johns Hopkins Wilmer Eye Institute, United States; Department of Ophthalmology, School of Medicine, Johns Hopkins University, Baltimore, MD 21218, United States.
| | - Elizabeth C Kimball
- Glaucoma Center of Excellence, Johns Hopkins Wilmer Eye Institute, United States.
| | - Sarah Quillen
- Glaucoma Center of Excellence, Johns Hopkins Wilmer Eye Institute, United States.
| | - Joan L Jefferys
- Glaucoma Center of Excellence, Johns Hopkins Wilmer Eye Institute, United States.
| | - Manasi Nawathe
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, United States.
| | - Yik Tung Tracy Ling
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, United States.
| | - Thao D Nguyen
- Department of Ophthalmology, School of Medicine, Johns Hopkins University, Baltimore, MD 21218, United States; Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, United States; Department of Materials Science, Johns Hopkins University, Baltimore, MD 21218, United States.
| | - Harry A Quigley
- Glaucoma Center of Excellence, Johns Hopkins Wilmer Eye Institute, United States; Department of Ophthalmology, School of Medicine, Johns Hopkins University, Baltimore, MD 21218, United States.
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10
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Tan Z, Guo Y, Shrestha M, Sun D, Gregory-Ksander M, Jakobs TC. Microglia depletion exacerbates retinal ganglion cell loss in a mouse model of glaucoma. Exp Eye Res 2022; 225:109273. [PMID: 36206859 PMCID: PMC10970711 DOI: 10.1016/j.exer.2022.109273] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 09/09/2022] [Accepted: 09/26/2022] [Indexed: 01/11/2023]
Abstract
To test whether depletion of microglia in the optic nerve head has a beneficial effect on retinal ganglion cell numbers and function, we depleted microglia by oral administration of the CSF1R antagonist PLX5622. Then, ocular hypertension was induced by unilateral injection of magnetic microbeads into the anterior chamber. Visual function was assessed with pattern electroretinography and measurement of the optomotor reflex. Retinal ganglion cell bodies and axons were counted and gene expression patterns in optic nerve head astrocytes were tested on freshly dissociated astrocytes. PLX5622 efficiently depleted microglia in the retina and the optic nerve head, but about 20% of microglia persisted in the myelinated optic nerve proper even after prolonged exposure to the drug. PLX5622 did not affect ganglion cell function by itself. Elevation of the IOP for four weeks led to the expected decrease in visual acuity and pattern ERG amplitude. Microglia ablation did not affect these parameters. Ganglion cell and axon numbers were counted histologically post mortem. Mice in the microglia depletion group showed a moderate but significantly greater loss of ganglion cells than the control group. At four weeks post microbead injection, gene expression patterns in optic nerve head astrocytes are consistent with an A2 (or neuroprotective) pattern. Microglia depletion blunted the up-regulation of A2 genes in astrocytes. In conclusion, microglia depletion is unlikely to protect retinal ganglion cells in early glaucoma.
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Affiliation(s)
- Zizhu Tan
- The First Affiliated Hospital of Xi'an Jiaotong University, 277 Yanta West Road, Xi'an, Shaanxi, 710061, China; Schepens Eye Research Institute/Massachusetts Eye and Ear, Harvard University School of Medicine, 20 Staniford Street, Boston, MA, 02114, USA
| | - Yinjie Guo
- Schepens Eye Research Institute/Massachusetts Eye and Ear, Harvard University School of Medicine, 20 Staniford Street, Boston, MA, 02114, USA; The Second Xiangya Hospital of Central South University, 139 Middle Renmin Road, Changsha, Hunan, 410011, China
| | - Maleeka Shrestha
- Schepens Eye Research Institute/Massachusetts Eye and Ear, Harvard University School of Medicine, 20 Staniford Street, Boston, MA, 02114, USA
| | - Daniel Sun
- Schepens Eye Research Institute/Massachusetts Eye and Ear, Harvard University School of Medicine, 20 Staniford Street, Boston, MA, 02114, USA
| | - Meredith Gregory-Ksander
- Schepens Eye Research Institute/Massachusetts Eye and Ear, Harvard University School of Medicine, 20 Staniford Street, Boston, MA, 02114, USA
| | - Tatjana C Jakobs
- Schepens Eye Research Institute/Massachusetts Eye and Ear, Harvard University School of Medicine, 20 Staniford Street, Boston, MA, 02114, USA.
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11
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Tang Y, Chen Y, Chen D. The heterogeneity of astrocytes in glaucoma. Front Neuroanat 2022; 16:995369. [PMID: 36466782 PMCID: PMC9714578 DOI: 10.3389/fnana.2022.995369] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 10/31/2022] [Indexed: 09/10/2023] Open
Abstract
Glaucoma is a leading cause of blindness with progressive degeneration of retinal ganglion cells. Aging and increased intraocular pressure (IOP) are major risk factors. Lowering IOP does not always stop the disease progression. Alternative ways of protecting the optic nerve are intensively studied in glaucoma. Astrocytes are macroglia residing in the retina, optic nerve head (ONH), and visual brain, which keep neuronal homeostasis, regulate neuronal activities and are part of the immune responses to the retina and brain insults. In this brief review, we discuss the activation and heterogeneity of astrocytes in the retina, optic nerve head, and visual brain of glaucoma patients and animal models. We also discuss some recent transgenic and gene knockout studies using glaucoma mouse models to clarify the role of astrocytes in the pathogenesis of glaucoma. Astrocytes are heterogeneous and play crucial roles in the pathogenesis of glaucoma, especially in the process of neuroinflammation and mitochondrial dysfunction. In astrocytes, overexpression of Stat3 or knockdown of IκKβ/p65, caspase-8, and mitochondrial uncoupling proteins (Ucp2) can reduce ganglion cell loss in glaucoma mouse models. Based on these studies, therapeutic strategies targeting the heterogeneity of reactive astrocytes by enhancing their beneficial reactivity or suppressing their detrimental reactivity are alternative options for glaucoma treatment in the future.
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Affiliation(s)
- Yunjing Tang
- Research Laboratory of Ophthalmology and Vision Sciences, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Yongjiang Chen
- The School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - Danian Chen
- Research Laboratory of Ophthalmology and Vision Sciences, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
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12
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Chaudhary P, Stowell C, Reynaud J, Gardiner SK, Yang H, Williams G, Williams I, Marsh-Armstrong N, Burgoyne CF. Optic Nerve Head Myelin-Related Protein, GFAP, and Iba1 Alterations in Non-Human Primates With Early to Moderate Experimental Glaucoma. Invest Ophthalmol Vis Sci 2022; 63:9. [PMID: 36239974 PMCID: PMC9586137 DOI: 10.1167/iovs.63.11.9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Purpose The purpose of this study was to test if optic nerve head (ONH) myelin basic protein (MBP), 2′,3′-cyclic nucleotide 3′-phosphodiesterase (CNPase), glial fibrillary acidic protein (GFAP), and ionized calcium binding adaptor molecule 1 (Iba1) proteins are altered in non-human primate (NHP) early/moderate experimental glaucoma (EG). Methods Following paraformaldehyde perfusion, control and EG eye ONH tissues from four NHPs were paraffin embedded and serially (5 µm) vertically sectioned. Anti-MBP, CNPase, GFAP, Iba1, and nuclear dye-stained sections were imaged using sub-saturating light intensities. Whole-section images were segmented creating anatomically consistent laminar (L) and retrolaminar (RL) regions/sub-regions. EG versus control eye intensity/pixel-cluster density data within L and two RL regions (RL1 [1-250 µm]/RL2 [251-500 µm] from L) were compared using random effects models within the statistical program “R.” Results EG eye retinal nerve fiber loss ranged from 0% to 20%. EG eyes’ MBP and CNPase intensity were decreased within the RL1 (MBP = 31.4%, P < 0.001; CNPase =62.3%, P < 0.001) and RL2 (MBP = 19.6%, P < 0.001; CNPase = 56.1%, P = 0.0004) regions. EG eye GFAP intensity was decreased in the L (41.6%, P < 0.001) and RL regions (26.7% for RL1, and 28.4% for RL2, both P < 0.001). Iba1+ and NucBlue pixel-cluster density were increased in the laminar (28.2%, P = 0.03 and 16.6%, P = 0.008) and both RL regions (RL1 = 37.3%, P = 0.01 and 23.7%, P = 0.0002; RL2 = 53.7%, P = 0.002 and 33.2%, P < 0.001). Conclusions Retrolaminar myelin disruption occurs early in NHP EG and may be accompanied by laminar and retrolaminar decreases in astrocyte process labeling and increases in microglial/ macrophage density. The mechanistic and therapeutic implications of these findings warrant further study.
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Affiliation(s)
- Priya Chaudhary
- Optic Nerve Head Research Laboratory, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States.,Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - Cheri Stowell
- Optic Nerve Head Research Laboratory, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States.,Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - Juan Reynaud
- Optic Nerve Head Research Laboratory, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States.,Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - Stuart K Gardiner
- Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - Hongli Yang
- Optic Nerve Head Research Laboratory, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States.,Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - Galen Williams
- Optic Nerve Head Research Laboratory, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States.,Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - Imee Williams
- Optic Nerve Head Research Laboratory, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States.,Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | | | - Claude F Burgoyne
- Optic Nerve Head Research Laboratory, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States.,Discoveries in Sight, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
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13
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Li Z, Peng F, Liu Z, Li S, Li L, Qian X. Mechanobiological responses of astrocytes in optic nerve head due to biaxial stretch. BMC Ophthalmol 2022; 22:368. [PMID: 36114477 PMCID: PMC9482189 DOI: 10.1186/s12886-022-02592-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 09/06/2022] [Indexed: 11/25/2022] Open
Abstract
Background Elevated intraocular pressure (IOP) is the main risk factor for glaucoma, which might cause the activation of astrocytes in optic nerve head. To determine the effect of mechanical stretch on the astrocytes, we investigated the changes in cell phenotype, proteins of interest and signaling pathways under biaxial stretch. Method The cultured astrocytes in rat optic nerve head were stretched biaxially by 10 and 17% for 24 h, respectively. Then, we detected the morphology, proliferation and apoptosis of the stretched cells, and performed proteomics analysis. Protein expression was analyzed by Isobaric tags for relative and absolute quantification (iTRAQ) mass spectrometry. Proteins of interest and signaling pathways were screened using Gene Ontology enrichment analysis and pathway enrichment analysis, and the results were verified by western blot and the gene-chip data from Gene Expression Omnibus (GEO) database. Result The results showed that rearrangement of the actin cytoskeleton in response to stimulation by mechanical stress and proliferation rate of astrocytes decreased under 10 and 17% stretch condition, while there was no significant difference on the apoptosis rate of astrocytes in both groups. In the iTRAQ quantitative experiment, there were 141 differential proteins in the 10% stretch group and 140 differential proteins in the 17% stretch group. These proteins include low-density lipoprotein receptor-related protein (LRP6), caspase recruitment domain family, member 10 (CARD10), thrombospondin 1 (THBS1) and tetraspanin (CD81). The western blot results of LRP6, THBS1 and CD81 were consistent with that of iTRAQ experiment. ANTXR2 and CARD10 were both differentially expressed in the mass spectrometry results and GEO database. We also screened out the signaling pathways associated with astrocyte activation, including Wnt/β–catenin pathway, NF-κB signaling pathway, PI3K-Akt signaling pathway, MAPK signaling pathway, Jak-STAT signaling pathway, ECM-receptor interaction, and transforming growth factor-β (TGF-β) signaling pathway. Conclusion Mechanical stimulation can induce changes in cell phenotype, some proteins and signaling pathways, which might be associated with astrocyte activation. These proteins and signaling pathways may help us have a better understanding on the activation of astrocytes and the role astrocyte activation played in glaucomatous optic neuropathy. Supplementary Information The online version contains supplementary material available at 10.1186/s12886-022-02592-8.
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14
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Strickland RG, Garner MA, Gross AK, Girkin CA. Remodeling of the Lamina Cribrosa: Mechanisms and Potential Therapeutic Approaches for Glaucoma. Int J Mol Sci 2022; 23:ijms23158068. [PMID: 35897642 PMCID: PMC9329908 DOI: 10.3390/ijms23158068] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/18/2022] [Accepted: 07/19/2022] [Indexed: 11/28/2022] Open
Abstract
Glaucomatous optic neuropathy is the leading cause of irreversible blindness in the world. The chronic disease is characterized by optic nerve degeneration and vision field loss. The reduction of intraocular pressure remains the only proven glaucoma treatment, but it does not prevent further neurodegeneration. There are three major classes of cells in the human optic nerve head (ONH): lamina cribrosa (LC) cells, glial cells, and scleral fibroblasts. These cells provide support for the LC which is essential to maintain healthy retinal ganglion cell (RGC) axons. All these cells demonstrate responses to glaucomatous conditions through extracellular matrix remodeling. Therefore, investigations into alternative therapies that alter the characteristic remodeling response of the ONH to enhance the survival of RGC axons are prevalent. Understanding major remodeling pathways in the ONH may be key to developing targeted therapies that reduce deleterious remodeling.
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Affiliation(s)
- Ryan G. Strickland
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (R.G.S.); (M.A.G.); (A.K.G.)
| | - Mary Anne Garner
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (R.G.S.); (M.A.G.); (A.K.G.)
| | - Alecia K. Gross
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (R.G.S.); (M.A.G.); (A.K.G.)
| | - Christopher A. Girkin
- Department of Ophthalmology and Vision Sciences, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Correspondence: ; Tel.: +1-205-325-8620
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15
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Kimball EC, Quillen S, Pease ME, Keuthan C, Nagalingam A, Zack DJ, Johnson TV, Quigley HA. Aquaporin 4 is not present in normal porcine and human lamina cribrosa. PLoS One 2022; 17:e0268541. [PMID: 35709078 PMCID: PMC9202842 DOI: 10.1371/journal.pone.0268541] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 05/03/2022] [Indexed: 02/02/2023] Open
Abstract
Aquaporin 4 is absent from astrocytes in the rodent optic nerve head, despite high expression in the retina and myelinated optic nerve. The purpose of this study was to quantify regional aquaporin channel expression in astrocytes of the porcine and human mouse optic nerve (ON). Ocular tissue sections were immunolabeled for aquaporins 1(AQP1), 4(AQP4), and 9(AQP9), myelin basic protein (MBP), glial fibrillary acidic protein (GFAP) and alpha-dystroglycan (αDG) for their presence in retina, lamina, myelin transition zone (MTZ, region just posterior to lamina) and myelinated ON (MON). Semi- quantification of AQP4 labeling & real-time quantitative PCR (qPCR) data were analyzed in retina and ON tissue. Porcine and control human eyes had abundant AQP4 in Müller cells, retinal astrocytes, and myelinated ON (MON), but minimal expression in the lamina cribrosa. AQP1 and AQP9 were present in retina, but not in the lamina. Immunolabeling of GFAP and αDG was similar in lamina, myelin transition zone (MTZ) and MON regions. Semi-quantitative AQP4 labeling was at background level in lamina, increasing in the MTZ, and highest in the MON (lamina vs MTZ, MON; p≤0.05, p≤0.01, respectively). Expression of AQP4 mRNA was minimal in lamina and substantial in MTZ and MON, while GFAP mRNA expression was uniform among the lamina, MTZ, and MON regions. Western blot assay showed AQP4 protein expression in the MON samples, but none was detected in the lamina tissue. The minimal presence of AQP4 in the lamina is a specific regional phenotype of astrocytes in the mammalian optic nerve head.
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Affiliation(s)
- Elizabeth C. Kimball
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Sarah Quillen
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Mary E. Pease
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Casey Keuthan
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Aru Nagalingam
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Donald J. Zack
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Thomas V. Johnson
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Harry A. Quigley
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
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16
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Strat AN, Kirschner A, Yoo H, Singh A, Bagué T, Li H, Herberg S, Ganapathy PS. Engineering a 3D hydrogel system to study optic nerve head astrocyte morphology and behavior. Exp Eye Res 2022; 220:109102. [PMID: 35525298 DOI: 10.1016/j.exer.2022.109102] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 04/21/2022] [Accepted: 04/28/2022] [Indexed: 11/19/2022]
Affiliation(s)
- Ana N Strat
- Department of Ophthalmology & Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; BioInspired Institute, Syracuse University, Syracuse, NY, 13244, USA
| | - Alexander Kirschner
- Department of Ophthalmology & Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Hannah Yoo
- Department of Ophthalmology & Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Ayushi Singh
- Department of Ophthalmology & Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; BioInspired Institute, Syracuse University, Syracuse, NY, 13244, USA; Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Tyler Bagué
- Department of Ophthalmology & Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Haiyan Li
- Department of Ophthalmology & Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; BioInspired Institute, Syracuse University, Syracuse, NY, 13244, USA; Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Samuel Herberg
- Department of Ophthalmology & Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; BioInspired Institute, Syracuse University, Syracuse, NY, 13244, USA; Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY, 13244, USA
| | - Preethi S Ganapathy
- Department of Ophthalmology & Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; BioInspired Institute, Syracuse University, Syracuse, NY, 13244, USA.
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17
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Dillinger AE, Weber GR, Mayer M, Schneider M, Göppner C, Ohlmann A, Shamonin M, Monkman GJ, Fuchshofer R. CCN2/CTGF—A Modulator of the Optic Nerve Head Astrocyte. Front Cell Dev Biol 2022; 10:864433. [PMID: 35493079 PMCID: PMC9047870 DOI: 10.3389/fcell.2022.864433] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 03/18/2022] [Indexed: 12/14/2022] Open
Abstract
In primary open-angle glaucoma (POAG), a neurodegenerative disease of the optic nerve (ON) and leading cause of blindness, the optic nerve head (ONH) undergoes marked structural extracellular matrix (ECM) changes, which contribute to its permanent deformation and to degeneration of ON axons. The remodeling process of the ECM causes changes in the biomechanical properties of the ONH and the peripapillary sclera, which is accompanied by an increased reactivity of the resident astrocytes. The molecular factors involved in the remodeling process belong to the Transforming growth factor (TGF)-β superfamily, especially TGF-β2. In previous publications we showed that TGF-β2 induced ECM alterations are mediated by Cellular Communication Network Factor (CCN)2/Connective Tissue Growth Factor (CTGF) and recently we showed that CCN2/CTGF is expressed by astrocytes of the ON under normal conditions. In this study we wanted to get a better understanding of the function of CCN2/CTGF under normal and pathologic conditions. To this end, we analyzed the glial lamina and peripapillary sclera of CCN2/CTGF overexpressing mice and studied the effect of CCN2/CTGF and increasing substratum stiffness on murine ON astrocytes in vitro. We observed enhanced astrocyte reactivity in the ONH, increased ECM protein synthesis in the peripapillary sclera and increased Ccn2/Ctgf expression in the ONH during the pathologic development in situ. CCN2/CTGF treatment of primary murine ON astrocytes induced a higher migration rate, and increase of ECM proteins including fibronectin, elastin and collagen type III. Furthermore, the astrocytes responded to stiffer substratum with increased glial fibrillary acidic protein, vimentin, actin and CCN2/CTGF synthesis. Finally, we observed the reinforced appearance of CCN2/CTGF in the lamina cribrosa of glaucomatous patients. We conclude that reactive changes in ONH astrocytes, induced by the altered biomechanical characteristics of the region, give rise to a self-amplifying process that includes increased TGF-β2/CCN2/CTGF signaling and leads to the synthesis of ECM molecules and cytoskeleton proteins, a process that in turn augments the stiffness at the ONH. Such a scenario may finally result in a vicious circle in the pathogenesis of POAG. The transgenic CTGF-overexpressing mouse model might be an optimal model to study the chronic pathological POAG changes in the ONH.
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Affiliation(s)
- Andrea E. Dillinger
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
| | - Gregor R. Weber
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
| | - Matthias Mayer
- Faculty of Electrical Engineering and Information Technology, Ostbayerische Technische Hochschule Regensburg, Regensburg, Germany
| | - Magdalena Schneider
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
| | - Corinna Göppner
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
| | - Andreas Ohlmann
- Department of Ophthalmology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Mikhail Shamonin
- Faculty of Electrical Engineering and Information Technology, Ostbayerische Technische Hochschule Regensburg, Regensburg, Germany
| | - Gareth J. Monkman
- Faculty of Electrical Engineering and Information Technology, Ostbayerische Technische Hochschule Regensburg, Regensburg, Germany
| | - Rudolf Fuchshofer
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
- *Correspondence: Rudolf Fuchshofer,
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18
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Molecular regulation of neuroinflammation in glaucoma: Current knowledge and the ongoing search for new treatment targets. Prog Retin Eye Res 2022; 87:100998. [PMID: 34348167 PMCID: PMC8803988 DOI: 10.1016/j.preteyeres.2021.100998] [Citation(s) in RCA: 53] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 07/23/2021] [Accepted: 07/26/2021] [Indexed: 12/11/2022]
Abstract
Neuroinflammation relying on the inflammatory responses of glial cells has emerged as an impactful component of the multifactorial etiology of neurodegeneration in glaucoma. It has become increasingly evident that despite early adaptive and reparative features of glial responses, prolonged reactivity of the resident glia, along with the peripheral immune cells, create widespread toxicity to retinal ganglion cell (RGC) axons, somas, and synapses. As much as the synchronized responses of astrocytes and microglia to glaucoma-related stress or neuron injury, their bi-directional interactions are critical to build and amplify neuroinflammation and to dictate the neurodegenerative outcome. Although distinct molecular programs regulate somatic and axonal degeneration in glaucoma, inhibition of neurodegenerative inflammation can provide a broadly beneficial treatment strategy to rescue RGC integrity and function. Since inflammatory toxicity and mitochondrial dysfunction are converging etiological paths that can boost each other and feed into a vicious cycle, anti-inflammatory treatments may also offer a multi-target potential. This review presents an overview of the current knowledge on neuroinflammation in glaucoma with particular emphasis on the cell-intrinsic and cell-extrinsic factors involved in the reciprocal regulation of glial responses, the interdependence between inflammatory and mitochondrial routes of neurodegeneration, and the research aspects inspiring for prospective immunomodulatory treatments. With the advent of powerful technologies, ongoing research on molecular and functional characteristics of glial responses is expected to accumulate more comprehensive and complementary information and to rapidly move the field forward to safe and effective modulation of the glial pro-inflammatory activities, while restoring or augmenting the glial immune-regulatory and neurosupport functions.
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Zhao J, Gonsalvez GB, Mysona BA, Smith SB, Bollinger KE. Sigma 1 Receptor Contributes to Astrocyte-Mediated Retinal Ganglion Cell Protection. Invest Ophthalmol Vis Sci 2022; 63:1. [PMID: 35103752 PMCID: PMC8819349 DOI: 10.1167/iovs.63.2.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 12/28/2021] [Indexed: 01/22/2023] Open
Abstract
Purpose Sigma 1 receptor (S1R) is expressed in retinal ganglion cells (RGCs) and astrocytes, and its activation is neuroprotective. We evaluated the contribution of S1R within optic nerve head astrocytes (ONHAs) to growth and survival of RGCs in vitro. Methods Wild-type (WT) RGCs and WT or S1R knockout (S1R KO) ONHAs were cocultured for 2, 4, or 7 days. Total and maximal neurite length, neurite root, and extremity counts were measured. Cell death was measured using a TUNEL assay. Signal transducer and activator of transcription 3 phosphorylation levels were evaluated in ONHA-derived lysates by immunoblotting. Results The coculture of WT RGCs with WT or S1R KO ONHAs increased the total and maximal neurite length. Neurite root and extremity counts increased at 4 and 7 days when WT RGCs were cocultured with WT or S1R KO ONHAs. At all timepoints, the total and maximal neurite length decreased for WT RGCs in coculture with S1R KO ONHAs compared with WT ONHAs. Root and extremity counts decreased for WT RGCs in coculture with S1R KO ONHAs compared with WT ONHAs at 2 and 7, but not 4 days. RGC apoptosis increased in S1R KO ONHA coculture and S1R KO-conditioned medium, compared with WT ONHA coculture or WT-conditioned medium. S1R KO ONHA-derived lysates showed decreased phosphorylated signal transducer and activator of transcription 3 levels compared with WT ONHA-derived lysates. Conclusions The absence of S1R within ONHAs has a deleterious effect on RGC neurite growth and RGC survival, reflected in analysis of WT RGC + S1R KO ONHA indirect cocultures. The data suggest that S1R may enhance ganglion cell survival via glia-mediated mechanisms.
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Affiliation(s)
- Jing Zhao
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Culver Vision Discovery Institute, Augusta, Georgia, United States
| | | | - Barbara A. Mysona
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Department of Cellular Biology and Anatomy, Augusta, Georgia, United States
- Culver Vision Discovery Institute, Augusta, Georgia, United States
| | - Sylvia B. Smith
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Department of Cellular Biology and Anatomy, Augusta, Georgia, United States
- Culver Vision Discovery Institute, Augusta, Georgia, United States
| | - Kathryn E. Bollinger
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Department of Cellular Biology and Anatomy, Augusta, Georgia, United States
- Culver Vision Discovery Institute, Augusta, Georgia, United States
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20
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Kirschner A, Strat AN, Yablonski J, Yoo H, Bagué T, Li H, Zhao J, Bollinger KE, Herberg S, Ganapathy PS. Mechanosensitive channel inhibition attenuates TGFβ2-induced actin cytoskeletal remodeling and reactivity in mouse optic nerve head astrocytes. Exp Eye Res 2021; 212:108791. [PMID: 34656548 DOI: 10.1016/j.exer.2021.108791] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 09/22/2021] [Accepted: 10/11/2021] [Indexed: 11/27/2022]
Abstract
Astrocytes within the optic nerve head undergo actin cytoskeletal rearrangement early in glaucoma, which coincides with astrocyte reactivity and extracellular matrix (ECM) deposition. Elevated transforming growth factor beta 2 (TGFβ2) levels within astrocytes have been described in glaucoma, and TGFβ signaling induces actin cytoskeletal remodeling and ECM deposition in many tissues. A key mechanism by which astrocytes sense and respond to external stimuli is via mechanosensitive ion channels. Here, we tested the hypothesis that inhibition of mechanosensitive channels will attenuate TGFβ2-mediated optic nerve head astrocyte actin cytoskeletal remodeling, reactivity, and ECM deposition. Primary optic nerve head astrocytes were isolated from C57BL/6J mice and cell purity was confirmed by immunostaining. Astrocytes were treated with vehicle control, TGFβ2 (5 ng/ml), GsMTx4 (a mechanosensitive channel inhibitor; 500 nM), or TGFβ2 (5 ng/ml) + GsMTx4 (500 nM) for 48 h. FITC-phalloidin staining was used to assess the formation of f-actin stress fibers and to quantify the presence of crosslinked actin networks (CLANs). Cell reactivity was determined by immunostaining and immunoblotting for GFAP. Levels of fibronectin and collagen IV deposition were also quantified. Primary optic nerve head astrocytes were positive for the astrocyte marker GFAP and negative for markers for microglia (F4/80) and oligodendrocytes (OSP1). Significantly increased %CLAN-positive cells were observed after 48-h treatment with TGFβ2 vs. control in a dose-dependent manner. Co-treatment with GsMTx4 significantly decreased %CLAN-positive cells vs. TGFβ2 treatment and the presence of f-actin stress fibers. TGFβ2 treatment significantly increased GFAP, fibronectin, and collagen IV levels, and GsMTx4 co-treatment ameliorated GFAP immunoreactivity. Our data suggest inhibition of mechanosensitive channel activity as a potential therapeutic strategy to modulate actin cytoskeletal remodeling within the optic nerve head in glaucoma.
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Affiliation(s)
- Alexander Kirschner
- Department of Ophthalmology & Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Ana N Strat
- Department of Ophthalmology & Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - John Yablonski
- Department of Ophthalmology & Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Hannah Yoo
- Department of Ophthalmology & Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Tyler Bagué
- Department of Ophthalmology & Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Haiyan Li
- Department of Ophthalmology & Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; BioInspired Institute, Syracuse University, Syracuse, NY, 13244, USA
| | - Jing Zhao
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA; Culver Vision Discovery Institute, Augusta, GA, 30912, USA
| | - Kathryn E Bollinger
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA; Culver Vision Discovery Institute, Augusta, GA, 30912, USA
| | - Samuel Herberg
- Department of Ophthalmology & Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; BioInspired Institute, Syracuse University, Syracuse, NY, 13244, USA; Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY, 13244, USA
| | - Preethi S Ganapathy
- Department of Ophthalmology & Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; BioInspired Institute, Syracuse University, Syracuse, NY, 13244, USA.
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Campagno KE, Lu W, Jassim AH, Albalawi F, Cenaj A, Tso HY, Clark SP, Sripinun P, Gómez NM, Mitchell CH. Rapid morphologic changes to microglial cells and upregulation of mixed microglial activation state markers induced by P2X7 receptor stimulation and increased intraocular pressure. J Neuroinflammation 2021; 18:217. [PMID: 34544431 PMCID: PMC8454080 DOI: 10.1186/s12974-021-02251-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 08/25/2021] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND The identification of endogenous signals that lead to microglial activation is a key step in understanding neuroinflammatory cascades. As ATP release accompanies mechanical strain to neural tissue, and as the P2X7 receptor for ATP is expressed on microglial cells, we examined the morphological and molecular consequences of P2X7 receptor stimulation in vivo and in vitro and investigated the contribution of the P2X7 receptor in a model of increased intraocular pressure (IOP). METHODS In vivo experiments involved intravitreal injections and both transient and sustained elevation of IOP. In vitro experiments were performed on isolated mouse retinal and brain microglial cells. Morphological changes were quantified in vivo using Sholl analysis. Expression of mRNA for M1- and M2-like genes was determined with qPCR. The luciferin/luciferase assay quantified retinal ATP release while fura-2 indicated cytoplasmic calcium. Microglial migration was monitored with a Boyden chamber. RESULTS Sholl analysis of Iba1-stained cells showed retraction of microglial ramifications 1 day after injection of P2X7 receptor agonist BzATP into mouse retinae. Mean branch length of ramifications also decreased, while cell body size and expression of Nos2, Tnfa, Arg1, and Chil3 mRNA increased. BzATP induced similar morphological changes in ex vivo tissue isolated from Cx3CR1+/GFP mice, suggesting recruitment of external cells was unnecessary. Immunohistochemistry suggested primary microglial cultures expressed the P2X7 receptor, while functional expression was demonstrated with Ca2+ elevation by BzATP and block by specific antagonist A839977. BzATP induced process retraction and cell body enlargement within minutes in isolated microglial cells and increased Nos2 and Arg1. While ATP increased microglial migration, this required the P2Y12 receptor and not P2X7 receptor. Transient elevation of IOP led to microglial process retraction, cell body enlargement, and gene upregulation paralleling changes observed with BzATP injection, in addition to retinal ATP release. Pressure-dependent changes were reduced in P2X7-/- mice. Death of retinal ganglion cells accompanied increased IOP in C57Bl/6J, but not P2X7-/- mice, and neuronal loss showed some association with microglial activation. CONCLUSIONS P2X7 receptor stimulation induced rapid morphological activation of microglial cells, including process retraction and cell body enlargement, and upregulation of markers linked to both M1- and M2-type activation. Parallel responses accompanied IOP elevation, suggesting ATP release and P2X7 receptor stimulation influence the early microglial response to increased pressure.
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Affiliation(s)
- Keith E Campagno
- Department of Basic and Translational Science, University of Pennsylvania, 240 S. 40th St, Philadelphia, PA, 19104, USA
| | - Wennan Lu
- Department of Basic and Translational Science, University of Pennsylvania, 240 S. 40th St, Philadelphia, PA, 19104, USA
| | - Assraa Hassan Jassim
- Department of Basic and Translational Science, University of Pennsylvania, 240 S. 40th St, Philadelphia, PA, 19104, USA
| | - Farraj Albalawi
- Department of Orthodontics, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Preventive Dental Sciences, College of Dentistry, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
- King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
| | - Aurora Cenaj
- Department of Basic and Translational Science, University of Pennsylvania, 240 S. 40th St, Philadelphia, PA, 19104, USA
| | - Huen-Yee Tso
- Department of Basic and Translational Science, University of Pennsylvania, 240 S. 40th St, Philadelphia, PA, 19104, USA
| | - Sophia P Clark
- Department of Basic and Translational Science, University of Pennsylvania, 240 S. 40th St, Philadelphia, PA, 19104, USA
| | - Puttipong Sripinun
- Department of Orthodontics, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Néstor Más Gómez
- Department of Basic and Translational Science, University of Pennsylvania, 240 S. 40th St, Philadelphia, PA, 19104, USA
| | - Claire H Mitchell
- Department of Basic and Translational Science, University of Pennsylvania, 240 S. 40th St, Philadelphia, PA, 19104, USA.
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Department of Physiology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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22
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Multifactorial Pathogenic Processes of Retinal Ganglion Cell Degeneration in Glaucoma towards Multi-Target Strategies for Broader Treatment Effects. Cells 2021; 10:cells10061372. [PMID: 34199494 PMCID: PMC8228726 DOI: 10.3390/cells10061372] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/14/2021] [Accepted: 05/29/2021] [Indexed: 02/06/2023] Open
Abstract
Glaucoma is a chronic neurodegenerative disease characterized by apoptosis of retinal ganglion cell (RGC) somas, degeneration of axons, and loss of synapses at dendrites and axon terminals. Glaucomatous neurodegeneration encompasses multiple triggers, multiple cell types, and multiple molecular pathways through the etiological paths with biomechanical, vascular, metabolic, oxidative, and inflammatory components. As much as intrinsic responses of RGCs themselves, divergent responses and intricate interactions of the surrounding glia also play decisive roles for the cell fate. Seen from a broad perspective, multitarget treatment strategies have a compelling pathophysiological basis to more efficiently manipulate multiple pathogenic processes at multiple injury sites in such a multifactorial neurodegenerative disease. Despite distinct molecular programs for somatic and axonal degeneration, mitochondrial dysfunction and glia-driven neuroinflammation present interdependent processes with widespread impacts in the glaucomatous retina and optic nerve. Since dysfunctional mitochondria stimulate inflammatory responses and proinflammatory mediators impair mitochondria, mitochondrial restoration may be immunomodulatory, while anti-inflammatory treatments protect mitochondria. Manipulation of these converging routes may thus allow a unified treatment strategy to protect RGC axons, somas, and synapses. This review presents an overview of recent research advancements with emphasis on potential treatment targets to achieve the best treatment efficacy to preserve visual function in glaucoma.
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23
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Zhao J, Gonsalvez G, Bartoli M, Mysona BA, Smith SB, Bollinger KE. Sigma 1 Receptor Modulates Optic Nerve Head Astrocyte Reactivity. Invest Ophthalmol Vis Sci 2021; 62:5. [PMID: 34086045 PMCID: PMC8185400 DOI: 10.1167/iovs.62.7.5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 05/03/2021] [Indexed: 12/04/2022] Open
Abstract
Purpose Stimulation of Sigma 1 Receptor (S1R) is neuroprotective in retina and optic nerve. S1R is expressed in both neurons and glia. The purpose of this work is to evaluate the ability of S1R to modulate reactivity responses of optic nerve head astrocytes (ONHAs) by investigating the extent to which S1R activation alters ONHA reactivity under conditions of ischemic cellular stress. Methods Wild type (WT) and S1R knockout (KO) ONHAs were derived and treated with vehicle or S1R agonist, (+)-pentazocine ((+)-PTZ). Cells were subjected to six hours of oxygen glucose deprivation (OGD) followed by 18 hours of re-oxygenation (OGD/R). Astrocyte reactivity responses were measured. Molecules that regulate ONHA reactivity, signal transducer and activator of transcription 3 (STAT3) and nuclear factor kappa B (NF-kB), were evaluated. Results Baseline glial fibrillary acidic protein (GFAP) levels were increased in nonstressed KO ONHAs compared with WT cultures. Baseline cellular migration was also increased in nonstressed KO ONHAs compared with WT. Treatment with (+)-PTZ increased cellular migration in nonstressed WT ONHAs but not in KO ONHAs. Exposure of both WT and KO ONHAs to ischemia (OGD/R), increased GFAP levels and cellular proliferation. However, (+)-PTZ treatment of OGD/R-exposed ONHAs enhanced GFAP levels, cellular proliferation, and cellular migration in WT but not KO cultures. The (+)-PTZ treatment of WT ONHAs also enhanced the OGD/R-induced increase in cellular pSTAT3 levels. However, treatment of WT ONHAs with (+)-PTZ abrogated the OGD/R-induced rise in NF-kB(p65) activation. Conclusions Under ischemic stress conditions, S1R activation enhanced ONHA reactivity characteristics. Future studies should address effects of these responses on RGC survival.
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Affiliation(s)
- Jing Zhao
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Culver Vision Discovery Institute, Augusta, Georgia, United States
| | - Graydon Gonsalvez
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
| | - Manuela Bartoli
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Culver Vision Discovery Institute, Augusta, Georgia, United States
| | - Barbara A. Mysona
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Culver Vision Discovery Institute, Augusta, Georgia, United States
| | - Sylvia B. Smith
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Culver Vision Discovery Institute, Augusta, Georgia, United States
| | - Kathryn E. Bollinger
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Culver Vision Discovery Institute, Augusta, Georgia, United States
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24
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Brazile BL, Yang B, Waxman S, Lam P, Voorhees AP, Hua Y, Loewen RT, Loewen NA, Rizzo JF, Jakobs T, Sigal IA. Lamina Cribrosa Capillaries Straighten as Intraocular Pressure Increases. Invest Ophthalmol Vis Sci 2021; 61:2. [PMID: 33001158 PMCID: PMC7545063 DOI: 10.1167/iovs.61.12.2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Purpose The purpose of this study was to visualize the lamina cribrosa (LC) capillaries and collagenous beams, measure capillary tortuosity (path length over straight end-to-end length), and determine if capillary tortuosity changes when intraocular pressure (IOP) increases. Methods Within 8 hours of sacrifice, 3 pig heads were cannulated via the external ophthalmic artery, perfused with PBS to remove blood, and then perfused with a fluorescent dye to label the capillaries. The posterior pole of each eye was mounted in a custom-made inflation chamber for control of IOP with simultaneous imaging. Capillaries and collagen beams were visualized with structured light illumination enhanced imaging at IOPs from 5 to 50 mm Hg at each 5 mm Hg increment. Capillary tortuosity was measured from the images and paired two-sample t-tests were used to assess for significant changes in relation to changes in IOP. Results Capillaries were highly tortuous at 15 mm Hg (up to 1.45). In all but one eye, tortuosity decreased significantly as IOP increased from 15 to 25 mm Hg (P < 0.01), and tortuosity decreased significantly in every eye as IOP increased from 15 to 40 mm Hg (P < 0.01). In only 16% of capillaries, tortuosity increased with elevated IOP. Capillaries had a surprisingly different topology from the collagen beams. Conclusions Although high capillary tortuosity is sometimes regarded as potentially problematic because it can reduce blood flow, LC capillary tortuosity may provide slack that mitigates against reduced flow and structural damage caused by excessive stretch under elevated IOP. We speculate that low capillary tortuosity could be a risk factor for damage under high IOP.
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Affiliation(s)
- Bryn L Brazile
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh Pennsylvania, United States
| | - Bin Yang
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh Pennsylvania, United States.,Department of Engineering, Duquesne University, Pittsburgh Pennsylvania, United States
| | - Susannah Waxman
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh Pennsylvania, United States
| | - Po Lam
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh Pennsylvania, United States
| | - Andrew P Voorhees
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh Pennsylvania, United States
| | - Yi Hua
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh Pennsylvania, United States
| | - Ralitsa T Loewen
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh Pennsylvania, United States
| | - Nils A Loewen
- Department of Ophthalmology, University of Würzburg, Würzburg, Germany
| | - Joseph F Rizzo
- Neuro-Ophthalmology Service, Department of Ophthalmology, Massachusetts Eye and Ear and Harvard Medical School, Boston, Massachusetts, United States
| | - Tatjana Jakobs
- Department of Ophthalmology, Harvard Medical School, Boston Massachusetts, United States
| | - Ian A Sigal
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh Pennsylvania, United States.,Department of Bioengineering, University of Pittsburgh, Pittsburgh Pennsylvania, United States
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25
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Schwaner SA, Perry RN, Kight AM, Winder E, Yang H, Morrison JC, Burgoyne CF, Ross Ethier C. Individual-Specific Modeling of Rat Optic Nerve Head Biomechanics in Glaucoma. J Biomech Eng 2021; 143:1091616. [PMID: 33210142 DOI: 10.1115/1.4049157] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Indexed: 02/04/2023]
Abstract
Glaucoma is the second leading cause of blindness worldwide and is characterized by the death of retinal ganglion cells (RGCs), the cells that send vision information to the brain. Their axons exit the eye at the optic nerve head (ONH), the main site of damage in glaucoma. The importance of biomechanics in glaucoma is indicated by the fact that elevated intraocular pressure (IOP) is a causative risk factor for the disease. However, exactly how biomechanical insult leads to RGC death is not understood. Although rat models are widely used to study glaucoma, their ONH biomechanics have not been characterized in depth. Therefore, we aimed to do so through finite element (FE) modeling. Utilizing our previously described method, we constructed and analyzed ONH models with individual-specific geometry in which the sclera was modeled as a matrix reinforced with collagen fibers. We developed eight sets of scleral material parameters based on results from our previous inverse FE study and used them to simulate the effects of elevated IOP in eight model variants of each of seven rat ONHs. Within the optic nerve, highest strains were seen inferiorly, a pattern that was consistent across model geometries and model variants. In addition, changing the collagen fiber direction to be circumferential within the peripapillary sclera resulted in more pronounced decreases in strain than changing scleral stiffness. The results from this study can be used to interpret data from rat glaucoma studies to learn more about how biomechanics affects RGC pathogenesis in glaucoma.
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Affiliation(s)
- Stephen A Schwaner
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332
| | - Robert N Perry
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA 22904
| | - Alison M Kight
- Department of Bioengineering, Stanford University, Stanford, CA 94305
| | - Emily Winder
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, GA 30332
| | - Hongli Yang
- Optic Nerve Head Research Laboratory, Discoveries in Sight Research Laboratories, Devers Eye Institute, Legacy Health System, Portland, OR 97210
| | - John C Morrison
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, OR 97239
| | - Claude F Burgoyne
- Optic Nerve Head Research Laboratory, Discoveries in Sight Research Laboratories, Devers Eye Institute, Legacy Health System, Portland, OR 97210
| | - C Ross Ethier
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, GA 30332
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García-Bermúdez MY, Freude KK, Mouhammad ZA, van Wijngaarden P, Martin KK, Kolko M. Glial Cells in Glaucoma: Friends, Foes, and Potential Therapeutic Targets. Front Neurol 2021; 12:624983. [PMID: 33796062 PMCID: PMC8007906 DOI: 10.3389/fneur.2021.624983] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 01/26/2021] [Indexed: 12/15/2022] Open
Abstract
Glaucoma is the second leading cause of blindness worldwide, affecting ~80 million people by 2020 (1, 2). The condition is characterized by a progressive loss of retinal ganglion cells (RGCs) and their axons accompanied by visual field loss. The underlying pathophysiology of glaucoma remains elusive. Glaucoma is recognized as a multifactorial disease, and lowering intraocular pressure (IOP) is the only treatment that has been shown to slow the progression of the condition. However, a significant number of glaucoma patients continue to go blind despite intraocular pressure-lowering treatment (2). Thus, the need for alternative treatment strategies is indisputable. Accumulating evidence suggests that glial cells play a significant role in supporting RGC function and that glial dysfunction may contribute to optic nerve disease. Here, we review recent advances in understanding the role of glial cells in the pathophysiology of glaucoma. A particular focus is on the dynamic and essential interactions between glial cells and RGCs and potential therapeutic approaches to glaucoma by targeting glial cells.
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Affiliation(s)
| | - Kristine K Freude
- Department for Veterinary and Animal Science, University of Copenhagen, Copenhagen, Denmark
| | - Zaynab A Mouhammad
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Peter van Wijngaarden
- Center for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC, Australia.,Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, VIC, Australia
| | - Keith K Martin
- Center for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC, Australia.,Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, VIC, Australia
| | - Miriam Kolko
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.,Department of Ophthalmology, Copenhagen University Hospital, Rigshospitalet-Glostrup, Glostrup, Denmark
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27
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Kimball E, Schaub J, Quillen S, Keuthan C, Pease ME, Korneva A, Quigley H. The role of aquaporin-4 in optic nerve head astrocytes in experimental glaucoma. PLoS One 2021; 16:e0244123. [PMID: 33529207 PMCID: PMC7853498 DOI: 10.1371/journal.pone.0244123] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 01/11/2021] [Indexed: 02/04/2023] Open
Abstract
PURPOSE To study aquaporin channel expression in astrocytes of the mouse optic nerve (ON) and the response to IOP elevation in mice lacking aquaporin 4 (AQP4 null). METHODS C57BL/6 (B6) and AQP4 null mice were exposed to bead-induced IOP elevation for 3 days (3D-IOP), 1 and 6 weeks. Mouse ocular tissue sections were immunolabeled against aquaporins 1(AQP1), 4(AQP4), and 9(AQP9). Ocular tissue was imaged to identify normal AQP distribution, ON changes, and axon loss after IOP elevation. Ultrastructure examination, cell proliferation, gene expression, and transport block were also analyzed. RESULTS B6 mice had abundant AQP4 expression in Müller cells, astrocytes of retina and myelinated ON (MON), but minimal AQP4in prelaminar and unmyelinated ON (UON). MON of AQP4 nulls had smaller ON area, smaller axon diameter, higher axon density, and larger proportionate axon area than B6 (all p≤0.05). Bead-injection led to comparable 3D-IOP elevation (p = 0.42) and axonal transport blockade in both strains. In B6, AQP4 distribution was unchanged after 3D-IOP. At baseline, AQP1 and AQP9 were present in retina, but not in UON and this was unaffected after IOP elevation in both strains. In 3D-IOP mice, ON astrocytes and microglia proliferated, more in B6 than AQP4 null. After 6 week IOP elevation, axon loss occurred equally in the two mouse types (24.6%, AQP4 null vs. 23.3%, B6). CONCLUSION Lack of AQP4 was neither protective nor detrimental to the effects of IOP elevation. The minimal presence of AQP4 in UON may be a vital aspect of the regionally specific phenotype of astrocytes in the mouse optic nerve head.
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Affiliation(s)
- Elizabeth Kimball
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Julie Schaub
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Sarah Quillen
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Casey Keuthan
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Mary Ellen Pease
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Arina Korneva
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Harry Quigley
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
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Korneva A, Kimball EC, Jefferys JL, Quigley HA, Nguyen TD. Biomechanics of the optic nerve head and peripapillary sclera in a mouse model of glaucoma. J R Soc Interface 2020; 17:20200708. [PMID: 33323053 PMCID: PMC7811579 DOI: 10.1098/rsif.2020.0708] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 11/17/2020] [Indexed: 01/09/2023] Open
Abstract
The deformation of the mouse astrocytic lamina (AL) and adjacent peripapillary sclera (PPS) was measured in response to elevated intraocular pressure. We subjected explanted mouse eyes to inflation testing, comparing control eyes to those 3 days and 6 weeks after induction of ocular hypertension (OHT) via ocular microbead injection. Laser scanning microscopy was used with second harmonic generation to image the collagenous PPS and two-photon fluorescence to image transgenic fluorescent astrocytes in the AL. Digital volume correlation was applied to calculate strains in the PPS and AL. The specimen-averaged strains were biaxial in the AL and PPS, with greater strain overall in the x- than y-direction in the AL and greater strain in the θ- than the r-direction in the PPS. Strains increased after 3-day OHT, with greater strain overall in the 3-day AL than control AL, and greater circumferential strain in the 3-day PPS than control PPS. In the 6-week OHT eyes, AL and PPS strains were similar overall to controls. This experimental glaucoma model demonstrated a dynamic change in the mechanical behaviour of the AL and PPS over time at the site of neuronal injury and remodelling in glaucoma.
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Affiliation(s)
- Arina Korneva
- Glaucoma Center of Excellence, Wilmer Eye Institute, John Hopkins University, Baltimore, MD, USA
| | - Elizabeth C. Kimball
- Glaucoma Center of Excellence, Wilmer Eye Institute, John Hopkins University, Baltimore, MD, USA
| | - Joan L. Jefferys
- Glaucoma Center of Excellence, Wilmer Eye Institute, John Hopkins University, Baltimore, MD, USA
| | - Harry A. Quigley
- Glaucoma Center of Excellence, Wilmer Eye Institute, John Hopkins University, Baltimore, MD, USA
| | - Thao D. Nguyen
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA
- Department of Ophthalmology, The Johns Hopkins University, Baltimore, MD 21218, USA
- Department of Materials Science, The Johns Hopkins University, Baltimore, MD 21218, USA
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Baudouin C, Kolko M, Melik-Parsadaniantz S, Messmer EM. Inflammation in Glaucoma: From the back to the front of the eye, and beyond. Prog Retin Eye Res 2020; 83:100916. [PMID: 33075485 DOI: 10.1016/j.preteyeres.2020.100916] [Citation(s) in RCA: 164] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 10/09/2020] [Accepted: 10/13/2020] [Indexed: 02/08/2023]
Abstract
The pathophysiology of glaucoma is complex, multifactorial and not completely understood. Elevated intraocular pressure (IOP) and/or impaired retinal blood flow may cause initial optic nerve damage. In addition, age-related oxidative stress in the retina concurrently with chronic mechanical and vascular stress is crucial for the initiation of retinal neurodegeneration. Oxidative stress is closely related to cell senescence, mitochondrial dysfunction, excitotoxicity, and neuroinflammation, which are involved in glaucoma progression. Accumulating evidence from animal glaucoma models and from human ocular samples suggests a dysfunction of the para-inflammation in the retinal ganglion cell layer and the optic nerve head. Moreover, quite similar mechanisms in the anterior chamber could explain the trabecular meshwork dysfunction and the elevated IOP in primary open-angle glaucoma. On the other hand, ocular surface disease due to topical interventions is the most prominent and visible consequence of inflammation in glaucoma, with a negative impact on filtering surgery failure, topical treatment efficacy, and possibly on inflammation in the anterior segment. Consequently, glaucoma appears as an outstanding eye disease where inflammatory changes may be present to various extents and consequences along the eye structure, from the ocular surface to the posterior segment, and the visual pathway. Here we reviewed the inflammatory processes in all ocular structures in glaucoma from the back to the front of the eye and beyond. Our approach was to explain how para-inflammation is necessary to maintain homoeostasis, and to describe abnormal inflammatory findings observed in glaucomatous patients or in animal glaucoma models, supporting the hypothesis of a dysregulation of the inflammatory balance toward a pro-inflammatory phenotype. Possible anti-inflammatory therapeutic approaches in glaucoma are also discussed.
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Affiliation(s)
- Christophe Baudouin
- Quinze-Vingts National Ophthalmology Hospital, INSERM-DGOS CIC 1423, IHU Foresight, Paris, France; Sorbonne Université, INSERM, CNRS, Institut de La Vision, Paris, France; Department of Ophthalmology, Ambroise Paré Hospital, APHP, Université de Versailles Saint-Quentin en Yvelines, Boulogne-Billancourt, France.
| | - Miriam Kolko
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark; Department of Ophthalmology, Copenhagen University Hospital, Rigshospitalet-Glostrup, Glostrup, Denmark
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Ling YTT, Pease ME, Jefferys JL, Kimball EC, Quigley HA, Nguyen TD. Pressure-Induced Changes in Astrocyte GFAP, Actin, and Nuclear Morphology in Mouse Optic Nerve. Invest Ophthalmol Vis Sci 2020; 61:14. [PMID: 32910133 PMCID: PMC7488631 DOI: 10.1167/iovs.61.11.14] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 08/12/2020] [Indexed: 12/17/2022] Open
Abstract
Purpose To conduct quantitative analysis of astrocytic glial fibrillary acidic protein (GFAP), actin and nuclei distribution in mouse optic nerve (ON) and investigate changes in the measured features after 3 days of ocular hypertension (OHT). Method Serial cross-sections of 3-day microbead-induced OHT and control ONs were fluorescently labelled and imaged using confocal microscope. Eighteen structural features were measured from the acquired images, including GFAP coverage, actin area fraction, process thickness, and aspect ratio of cell nucleus. The measured features were analyzed for variations with axial locations along ON and radial zones transverse to ON, as well as for the correlations with degree of intraocular pressure (IOP) change. Results The most significant changes in structural features after 3-day OHT occurred in the unmyelinated ON region (R1), and the changes were greater with greater IOP elevation. Although the GFAP, actin, axonal, and ON areas all increased in 3-day OHT ONs in R1 (P ≤ 0.004 for all), the area fraction of GFAP actually decreased (P = 0.02), the actin area fraction was stable and individual axon compartments were unchanged in size. Within R1, the number of nuclear clusters increased (P < 0.001), but the mean size of nuclear clusters was smaller (P = 0.02) and the clusters became rounder (P < 0.001). In all cross-sections of control ONs, astrocytic processes were thickest in the rim zone compared with the central and peripheral zones (P ≤ 0.002 for both), whereas the overall process width in R1 decreased after 3 days of OHT (P < 0.001). Conclusions The changes in structure elucidated IOP-generated alterations that underlie astrocyte mechanotranslational responses relevant to glaucoma.
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Affiliation(s)
- Yik Tung Tracy Ling
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland, United States
| | - Mary E. Pease
- Wilmer Ophthalmological Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - Joan L. Jefferys
- Wilmer Ophthalmological Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - Elizabeth C. Kimball
- Wilmer Ophthalmological Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - Harry A. Quigley
- Wilmer Ophthalmological Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - Thao D. Nguyen
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland, United States
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Quillen S, Schaub J, Quigley H, Pease M, Korneva A, Kimball E. Astrocyte responses to experimental glaucoma in mouse optic nerve head. PLoS One 2020; 15:e0238104. [PMID: 32822415 PMCID: PMC7442264 DOI: 10.1371/journal.pone.0238104] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 08/10/2020] [Indexed: 12/20/2022] Open
Abstract
PURPOSE To delineate responses of optic nerve head astrocytes to sustained intraocular pressure (IOP) elevation in mice. METHODS We elevated IOP for 1 day to 6 weeks by intracameral microbead injection in 4 strains of mice. Astrocyte alterations were studied by transmission electron microscopy (TEM) including immunogold molecular localization, and by laser scanning microscopy (LSM) with immunofluorescence for integrin β1, α-dystroglycan, and glial fibrillary acidic protein (GFAP). Astrocyte proliferation and apoptosis were quantified by Ki67 and TUNEL labeling, respectively. RESULTS Astrocytes in normal optic nerve head expressed integrin β1 and α-dystroglycan by LSM and TEM immunogold labeling at electron dense junctional complexes that were found only on cell membrane zones bordering their basement membranes (BM) at the peripapillary sclera (PPS) and optic nerve head capillaries. At 1-3 days after IOP elevation, abnormal extracellular spaces appeared between astrocytes near PPS, and axonal vesical and mitochondrial accumulation indicated axonal transport blockade. By 1 week, abnormal spaces increased, new collagen formation occurred, and astrocytes separated from their BM, leaving cell membrane fragments. Electron dense junctional complexes separated or were absent at the BM. Astrocyte proliferation was modest during the first week, while only occasional apoptotic astrocytes were observed by TEM and TUNEL. CONCLUSIONS Astrocytes normally exhibit junctions with their BM which are disrupted by extended IOP elevation. Responses include reorientation of cell processes, new collagen formation, and cell proliferation.
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Affiliation(s)
- Sarah Quillen
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Julie Schaub
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Harry Quigley
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Mary Pease
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Arina Korneva
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Elizabeth Kimball
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
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Jung KI, Woo JE, Park CK. Intraocular pressure fluctuation and neurodegeneration in the diabetic rat retina. Br J Pharmacol 2020; 177:3046-3059. [PMID: 32087615 PMCID: PMC7279969 DOI: 10.1111/bph.15033] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 02/12/2020] [Accepted: 02/14/2020] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND AND PURPOSE Early retinal neurodegeneration occurs as one of the complications of diabetes even before clinically detectable diabetic vascular retinopathy. The pathogenesis of retinal diabetic neuropathy is still not well understood. We investigated the serial changes or fluctuations in intraocular pressure (IOP) and examined their roles in the pathogenesis of neuronal degeneration in diabetic retina. EXPERIMENTAL APPROACH Male Sprague Dawley rats with streptozotocin-induced diabetes were treated with ophthalmic preparations of brinzolamide, latanoprost, both drugs (combined treatment) or saline for 8 weeks. IOP was measured daily under general anaesthesia using a rebound tonometer. Antegrade axoplasmic flow in the optic nerve was assessed with a fluorescent substrate. Immunohistochemical staining, TUNEL assays and western blots were also used. KEY RESULTS The fluctuation of IOP was higher in the diabetes group than in the normal control or the combined treatment group. Diabetes-induced apoptosis of retinal ganglion cells was decreased by combined treatment. Increased expression of glial fibrillary acidic protein or Iba-1 in the retina or optic nerve head, induced by diabetes, was attenuated only by the combined treatment. Intercellular adhesion molecule-1 was increased in diabetic rats but not in the combined treatment group. Diabetes-induced loss of antegrade axoplasmic transport was partially relieved with combined treatment. CONCLUSION AND IMPLICATIONS Elevated IOP fluctuations seemed to be associated with the gliosis, neuroinflammation, and neurodegeneration induced by diabetes. The loss of retinal ganglion cells might be relieved by IOP-lowering medication. The improvement of unstable perfusion pressure could play a role in neuroprotection in the diabetic retina.
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Affiliation(s)
- Kyoung In Jung
- Department of Ophthalmology, Seoul St. Mary's Hospital, College of MedicineThe Catholic University of KoreaSeoulKorea
| | - Jung Eun Woo
- Department of Ophthalmology, Seoul St. Mary's Hospital, College of MedicineThe Catholic University of KoreaSeoulKorea
| | - Chan Kee Park
- Department of Ophthalmology, Seoul St. Mary's Hospital, College of MedicineThe Catholic University of KoreaSeoulKorea
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Oikawa K, Ver Hoeve JN, Teixeira LBC, Snyder KC, Kiland JA, Ellinwood NM, McLellan GJ. Sub-region-Specific Optic Nerve Head Glial Activation in Glaucoma. Mol Neurobiol 2020; 57:2620-2638. [PMID: 32266645 DOI: 10.1007/s12035-020-01910-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 03/23/2020] [Indexed: 12/22/2022]
Abstract
Glaucoma, a multifactorial neurodegenerative disease characterized by progressive loss of retinal ganglion cells and their axons in the optic nerve, is a leading cause of irreversible vision loss. Intraocular pressure (IOP) is a risk factor for axonal damage, which initially occurs at the optic nerve head (ONH). Complex cellular and molecular mechanisms involved in the pathogenesis of glaucomatous optic neuropathy remain unclear. Here we define early molecular events in the ONH in an inherited large animal glaucoma model in which ONH structure resembles that of humans. Gene expression profiling of ONH tissues from rigorously phenotyped feline subjects with early-stage glaucoma and precisely age-matched controls was performed by RNA-sequencing (RNA-seq) analysis and complementary bioinformatic approaches applied to identify molecular processes and pathways of interest. Immunolabeling supported RNA-seq findings while providing cell-, region-, and disease stage-specific context in the ONH in situ. Transcriptomic evidence for cell proliferation and immune/inflammatory responses is identifiable in early glaucoma, soon after IOP elevation and prior to morphologically detectable axon loss, in this large animal model. In particular, proliferation of microglia and oligodendrocyte precursor cells is a prominent feature of early-stage, but not chronic, glaucoma. ONH microgliosis is a consistent hallmark in both early and chronic stages of glaucoma. Molecular pathways and cell type-specific responses strongly implicate toll-like receptor and NF-κB signaling in early glaucoma pathophysiology. The current study provides critical insights into molecular pathways, highly dependent on cell type and sub-region in the ONH even prior to irreversible axon degeneration in glaucoma.
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Affiliation(s)
- Kazuya Oikawa
- Department of Surgical Sciences, University of Wisconsin-Madison, Madison, WI, USA
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, 1300 University Avenue, Madison, WI, 53706, USA
- McPherson Eye Research Institute, Madison, WI, USA
| | - James N Ver Hoeve
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, 1300 University Avenue, Madison, WI, 53706, USA
- McPherson Eye Research Institute, Madison, WI, USA
| | - Leandro B C Teixeira
- McPherson Eye Research Institute, Madison, WI, USA
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Kevin C Snyder
- Department of Surgical Sciences, University of Wisconsin-Madison, Madison, WI, USA
- McPherson Eye Research Institute, Madison, WI, USA
| | - Julie A Kiland
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, 1300 University Avenue, Madison, WI, 53706, USA
| | | | - Gillian J McLellan
- Department of Surgical Sciences, University of Wisconsin-Madison, Madison, WI, USA.
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, 1300 University Avenue, Madison, WI, 53706, USA.
- McPherson Eye Research Institute, Madison, WI, USA.
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Schwaner SA, Feola AJ, Ethier CR. Factors affecting optic nerve head biomechanics in a rat model of glaucoma. J R Soc Interface 2020; 17:20190695. [PMID: 32228401 DOI: 10.1098/rsif.2019.0695] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Glaucoma is the leading cause of irreversible blindness and is characterized by the death of retinal ganglion cells, which carry vision information from the retina to the brain. Although it is well accepted that biomechanics is an important part of the glaucomatous disease process, the mechanisms by which biomechanical insult, usually due to elevated intraocular pressure (IOP), leads to retinal ganglion cell death are not understood. Rat models of glaucoma afford an opportunity for learning more about these mechanisms, but the biomechanics of the rat optic nerve head (ONH), a primary region of damage in glaucoma, are only just beginning to be characterized. In a previous study, we built finite-element models with individual-specific rat ONH geometries. Here, we developed a parametrized model of the rat ONH and used it to perform a sensitivity study to determine the influence that six geometric parameters and 13 tissue material properties have on rat optic nerve biomechanical strains due to IOP elevation. Strain magnitudes and patterns in the parametrized model generally matched those from individual-specific models, suggesting that the parametrized model sufficiently approximated rat ONH anatomy. Similar to previous studies in human eyes, we found that scleral properties were highly influential: the six parameters with highest influence on optic nerve strains were optic nerve stiffness, IOP, scleral thickness, the degree of alignment of scleral collagen fibres, scleral ground substance stiffness and the scleral collagen fibre uncrimping coefficient. We conclude that a parametrized modelling strategy is an efficient approach that allows insight into rat ONH biomechanics. Further, scleral properties are important influences on rat ONH biomechanics, and additional efforts should be made to better characterize rat scleral collagen fibre organization.
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Affiliation(s)
- Stephen A Schwaner
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Andrew J Feola
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA.,Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Atlanta, GA, USA
| | - C Ross Ethier
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA.,Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
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Lee EJ, Han JC, Park DY, Kee C. A neuroglia-based interpretation of glaucomatous neuroretinal rim thinning in the optic nerve head. Prog Retin Eye Res 2020; 77:100840. [PMID: 31982595 DOI: 10.1016/j.preteyeres.2020.100840] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 01/02/2020] [Accepted: 01/13/2020] [Indexed: 12/14/2022]
Abstract
Neuroretinal rim thinning (NRR) is a characteristic glaucomatous optic disc change. However, the precise mechanism of the rim thinning has not been completely elucidated. This review focuses on the structural role of the glioarchitecture in the formation of the glaucomatous NRR thinning. The NRR is a glia-framed structure, with honeycomb geometry and mechanically reinforced astrocyte processes along the transverse plane. When neural damage selectively involves the neuron and spares the glia, the gross structure of the tissue is preserved. The disorganization and loss of the glioarchitecture are the two hallmarks of optic nerve head (ONH) remodeling in glaucoma that leads to the thinning of NRR tissue upon axonal loss. This is in contrast to most non-glaucomatous optic neuropathies with optic disc pallor where hypertrophy of the glioarchitecture is associated with the seemingly absent optic disc cupping. Arteritic anterior ischemic optic neuropathy is an exception where pan-necrosis of ONH tissue leads to NRR thinning. Milder ischemia indicates selective neuronal loss that spares glia in non-arteritic anterior ischemic optic neuropathy. The biological reason is the heterogeneous glial response determined by the site, type, and severity of the injury. The neuroglial interpretation explains how the cellular changes underlie the clinical findings. Updated understandings on glial responses illustrate the mechanical, microenvironmental, and microglial modulation of activated astrocytes in glaucoma. Findings relevant to the possible mechanism of the astrocyte death in advanced glaucoma are also emerging. Ultimately, a better understanding of glaucomatous glial response may lead to glia-targeting neuroprotection in the future.
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Affiliation(s)
- Eun Jung Lee
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-Ro, Gangnam-gu, Seoul, 06351, South Korea
| | - Jong Chul Han
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-Ro, Gangnam-gu, Seoul, 06351, South Korea
| | - Do Young Park
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-Ro, Gangnam-gu, Seoul, 06351, South Korea
| | - Changwon Kee
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-Ro, Gangnam-gu, Seoul, 06351, South Korea.
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Ma Y, Pavlatos E, Clayson K, Kwok S, Pan X, Liu J. Three-Dimensional Inflation Response of Porcine Optic Nerve Head Using High-Frequency Ultrasound Elastography. J Biomech Eng 2020; 142:1069480. [PMID: 31750882 DOI: 10.1115/1.4045503] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Indexed: 12/29/2022]
Abstract
Characterization of the biomechanical behavior of the optic nerve head (ONH) in response to intraocular pressure (IOP) elevation is important for understanding glaucoma susceptibility. In this study, we aimed to develop and validate a three-dimensional (3D) ultrasound elastographic technique to obtain mapping and visualization of the 3D distributive displacements and strains of the ONH and surrounding peripapillary tissue (PPT) during whole globe inflation from 15 to 30 mmHg. 3D scans of the posterior eye around the ONH were acquired through full tissue thickness with a high-frequency ultrasound system (50 MHz). A 3D cross-correlation-based speckle-tracking algorithm was used to compute tissue displacements at ∼30,000 kernels distributed within the region of interest (ROI), and the components of the strain tensors were calculated at each kernel by using least square estimation of the displacement gradients. The accuracy of displacement calculation was evaluated using simulated rigid-body translation on ultrasound radiofrequency (RF) data obtained from a porcine posterior eye. The accuracy of strain calculation was evaluated using finite element (FE) models. Three porcine eyes were tested showing that ONH deformation was heterogeneous with localized high strains. Substantial radial (i.e., through-thickness) compression was observed in the anterior ONH and out-of-plane (i.e., perpendicular to the surface of the shell) shear was shown to concentrate in the vicinity of ONH/PPT border. These preliminary results demonstrated the feasibility of this technique to achieve comprehensive 3D evaluation of the mechanical responses of the posterior eye, which may provide mechanistic insights into the regional susceptibility in glaucoma.
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Affiliation(s)
- Yanhui Ma
- Department of Biomedical Engineering, Ohio State University, 1080 Carmack Road, Columbus, OH 43210
| | - Elias Pavlatos
- Department of Biomedical Engineering, Ohio State University, 1080 Carmack Road, Columbus, OH 43210
| | - Keyton Clayson
- Department of Biomedical Engineering, Ohio State University, 1080 Carmack Road, Columbus, OH 43210
| | - Sunny Kwok
- Department of Biomedical Engineering, Ohio State University, 1080 Carmack Road, Columbus, OH 43210
| | - Xueliang Pan
- Department of Biomedical Informatics, Ohio State University, 1800 Cannon Drive, Columbus, OH 43210
| | - Jun Liu
- Department of Biomedical Engineering, Ohio State University, 1080 Carmack Road, Columbus, OH 43210
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Experimental glaucoma model with controllable intraocular pressure history. Sci Rep 2020; 10:126. [PMID: 31924837 PMCID: PMC6954231 DOI: 10.1038/s41598-019-57022-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 12/18/2019] [Indexed: 12/20/2022] Open
Abstract
Glaucoma-like neuropathies can be experimentally induced by disturbing aqueous outflow from the eye, resulting in intraocular pressure (IOP) changes that are variable in magnitude and time course and permanent in duration. This study introduces a novel method of glaucoma induction that offers researchers round-the-clock measurement and reversible control of IOP for the first time. One eye of Brown-Norway rats was implanted with a cannula tethered to a pressure sensor and aqueous reservoir. IOP was raised 10 mmHg for weeks-to-months in treated animals and unaltered in control animals. Counts of Brn3a-expressing retinal ganglion cells (RGCs) in implanted eyes were indistinguishable from non-implanted eyes in control animals and 15 ± 2%, 23 ± 4%, and 38 ± 4% lower in animals exposed to 2, 4, and 9 weeks of IOP elevation. RGC loss was greater in peripheral retina at 2 weeks and widespread at longer durations. Optic nerves also showed progressive degeneration with exposure duration, yet conventional outflow facility of implanted eyes was normal (24.1 ± 2.9 nl/min/mmHg) even after 9-weeks elevation. Hence, this infusion-based glaucoma model exhibits graded neural damage with unimpaired outflow pathways. The model further revealed a potentially-significant finding that outflow properties of rat eyes do not remodel in response to chronic ocular hypertension.
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Ling YTT, Shi R, Midgett DE, Jefferys JL, Quigley HA, Nguyen TD. Characterizing the Collagen Network Structure and Pressure-Induced Strains of the Human Lamina Cribrosa. Invest Ophthalmol Vis Sci 2019; 60:2406-2422. [PMID: 31157833 PMCID: PMC6545820 DOI: 10.1167/iovs.18-25863] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Purpose The purpose of this study was to measure the 2D collagen network structure of the human lamina cribrosa (LC), analyze for the correlations with age, region, and LC size, as well as the correlations with pressure-induced strains. Methods The posterior scleral cups of 10 enucleated human eyes with no known ocular disease were subjected to ex vivo inflation testing from 5 to 45 mm Hg. The optic nerve head was imaged by using second harmonic generation imaging (SHG) to identify the LC collagen structure at both pressures. Displacements and strains were calculated by using digital volume correlation of the SHG volumes. Nine structural features were measured by using a custom Matlab image analysis program, including the pore area fraction, node density, and beam connectivity, tortuosity, and anisotropy. Results All strain measures increased significantly with higher pore area fraction, and all but the radial-circumferential shear strain (Erθ) decreased with higher node density. The maximum principal strain (Emax) and maximum shear strain (Γmax) also increased with larger beam aspect ratio and tortuosity, respectively, and decreased with higher connectivity. The peripheral regions had lower node density and connectivity, and higher pore area fraction, tortuosity, and strains (except for Erθ) than the central regions. The peripheral nasal region had the lowest Emax, Γmax, radial strain, and pore area fraction. Conclusions Features of LC beam network microstructure that are indicative of greater collagen density and connectivity are associated with lower pressure-induced LC strain, potentially contributing to resistance to glaucomatous damage.
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Affiliation(s)
- Yik Tung Tracy Ling
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland, United States
| | - Ran Shi
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland, United States.,Department of Materials Science and Engineering, Beijing Institute of Technology, Beijing, China
| | - Dan E Midgett
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland, United States
| | - Joan L Jefferys
- Wilmer Ophthalmological Institute, School of Medicine, The Johns Hopkins University, Baltimore, Maryland, United States
| | - Harry A Quigley
- Wilmer Ophthalmological Institute, School of Medicine, The Johns Hopkins University, Baltimore, Maryland, United States
| | - Thao D Nguyen
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland, United States
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Schwaner SA, Kight AM, Perry RN, Pazos M, Yang H, Johnson EC, Morrison JC, Burgoyne CF, Ross Ethier C. A Methodology for Individual-Specific Modeling of Rat Optic Nerve Head Biomechanics in Glaucoma. J Biomech Eng 2019; 140:2679249. [PMID: 30003249 DOI: 10.1115/1.4039998] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Indexed: 12/20/2022]
Abstract
Glaucoma is the leading cause of irreversible blindness and involves the death of retinal ganglion cells (RGCs). Although biomechanics likely contributes to axonal injury within the optic nerve head (ONH), leading to RGC death, the pathways by which this occurs are not well understood. While rat models of glaucoma are well-suited for mechanistic studies, the anatomy of the rat ONH is different from the human, and the resulting differences in biomechanics have not been characterized. The aim of this study is to describe a methodology for building individual-specific finite element (FE) models of rat ONHs. This method was used to build three rat ONH FE models and compute the biomechanical environment within these ONHs. Initial results show that rat ONH strains are larger and more asymmetric than those seen in human ONH modeling studies. This method provides a framework for building additional models of normotensive and glaucomatous rat ONHs. Comparing model strain patterns with patterns of cellular response seen in studies using rat glaucoma models will help us to learn more about the link between biomechanics and glaucomatous cell death, which in turn may drive the development of novel therapies for glaucoma.
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Affiliation(s)
- Stephen A Schwaner
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 315 Ferst Drive, 2306 IBB, Atlanta, GA 30332 e-mail:
| | - Alison M Kight
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, GA 30332 e-mail:
| | - Robert N Perry
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, GA 30332 e-mail:
| | - Marta Pazos
- Institut Clínic d'Oftalmologia, Hospital Clínic de Barcelona, Barcelona 08036, Spain e-mail:
| | - Hongli Yang
- Optic Nerve Head Research Laboratory, Discoveries in Sight Research Laboratories, Devers Eye Institute, Legacy Health System, Portland, OR 97210 e-mail:
| | - Elaine C Johnson
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, OR 97239 e-mail:
| | - John C Morrison
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, OR 97239 e-mail:
| | - Claude F Burgoyne
- Optic Nerve Head Research Laboratory, Discoveries in Sight Research Laboratories, Devers Eye Institute, Legacy Health System, Portland, OR 97210 e-mail:
| | - C Ross Ethier
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, GA 30332 e-mail:
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40
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Tehrani S, Davis L, Cepurna WO, Delf RK, Lozano DC, Choe TE, Johnson EC, Morrison JC. Optic Nerve Head Astrocytes Display Axon-Dependent and -Independent Reactivity in Response to Acutely Elevated Intraocular Pressure. Invest Ophthalmol Vis Sci 2019; 60:312-321. [PMID: 30665231 PMCID: PMC6343680 DOI: 10.1167/iovs.18-25447] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Purpose Optic nerve head (ONH) astrocytes provide support for axons, but exhibit structural and functional changes (termed reactivity) in a number of glaucoma models. The purpose of this study was to determine if ONH astrocyte structural reactivity is axon-dependent. Methods Using rats, we combine retrobulbar optic nerve transection (ONT) with acute controlled elevation of intraocular pressure (CEI), to induce total optic nerve axon loss and ONH astrocyte reactivity, respectively. Animals were euthanized immediately or 1 day post CEI, in the presence or absence of ONT. ONH sections were labeled with fluorescent-tagged phalloidin and antibodies against β3 tubulin, phosphorylated cortactin, phosphorylated paxillin, or complement C3. ONH label intensities were quantified after confocal microscopy. Retrobulbar nerves were assessed for axon injury by light microscopy. Results While ONT alone had no effect on ONH astrocyte structural orientation, astrocytes demonstrated significant reorganization of cellular extensions within hours after CEI, even when combined with ONT. However, ONH astrocytes displayed differential intensities of actin (phosphorylated cortactin) and focal adhesion (phosphorylated paxillin) mediators in response to CEI alone, ONT alone, or the combination of CEI and ONT. Lastly, label intensities of complement C3 within the ONH were unchanged in eyes subjected to CEI alone, ONT alone, or the combination of CEI and ONT, relative to controls. Conclusions Early ONH astrocyte structural reactivity to elevated IOP is multifaceted, displaying both axon dependent and independent responses. These findings have important implications for pursuing astrocytes as diagnostic and therapeutic targets in neurodegenerative disorders with fluctuating levels of axon injury.
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Affiliation(s)
- Shandiz Tehrani
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, Oregon, United States
| | - Lauren Davis
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, Oregon, United States
| | - William O Cepurna
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, Oregon, United States
| | - R Katherine Delf
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, Oregon, United States
| | - Diana C Lozano
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, Oregon, United States
| | - Tiffany E Choe
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, Oregon, United States
| | - Elaine C Johnson
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, Oregon, United States
| | - John C Morrison
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, Oregon, United States
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41
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Brazile BL, Hua Y, Jan NJ, Wallace J, Gogola A, Sigal IA. Thin Lamina Cribrosa Beams Have Different Collagen Microstructure Than Thick Beams. Invest Ophthalmol Vis Sci 2019; 59:4653-4661. [PMID: 30372734 PMCID: PMC6149225 DOI: 10.1167/iovs.18-24763] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Purpose To compare the collagen microstructural crimp characteristics between thin and thick lamina cribrosa (LC) beams. Methods Seven eyes from four sheep were fixed at 5 mm Hg IOP in 10% formalin. For each eye, one to three coronal cryosections through the LC were imaged with polarized light microscopy and analyzed to visualize the LC and determine collagen fiber microstructure. For every beam, we measured its width and three characteristics of the crimp of its collagen fibers: waviness, tortuosity, and amplitude. Linear mixed effects models were used to test whether crimp characteristics were associated with the LC beam width. Results For each eye and over all the eyes, LC beam width was positively associated with crimp waviness and tortuosity, and negatively associated with crimp amplitude (P's < 0.0001). Thin beams, average width 13.11 μm, had average (SD) waviness, tortuosity, and amplitude of 0.27 (0.17) radians, 1.017 (0.028) and 1.88 (1.41) μm, respectively. For thick beams, average width 26.10 μm, these characteristics were 0.33 (0.18) radians, 1.025 (0.037) and 1.58 (1.36) μm, respectively. Conclusions Our results suggest heterogeneity in LC beam mechanical properties. Thin beams were less wavy than their thicker counterparts, suggesting that thin beams may stiffen at lower IOP than thick beams. This difference may allow thin beams to support similar amounts of IOP-induced force as thicker beams, thus providing a similar level of structural support to the axons at physiologic IOP, despite the differences in width. Measurements of beam-level mechanical properties are needed to confirm these predictions.
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Affiliation(s)
- Bryn L Brazile
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Yi Hua
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Ning-Jiun Jan
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States.,Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Jacob Wallace
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Alexandra Gogola
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Ian A Sigal
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States.,Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States.,McGowan Institute for Regenerative Medicine, University of Pittsburgh School of Medicine and University of Pittsburgh, Pittsburgh, Pennsylvania, United States.,The Louis J. Fox Center for Vision Restoration of UPMC and the University of Pittsburgh, Pittsburgh, Pennsylvania, United States
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42
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Zhu Y, Pappas AC, Wang R, Seifert P, Sun D, Jakobs TC. Ultrastructural Morphology of the Optic Nerve Head in Aged and Glaucomatous Mice. Invest Ophthalmol Vis Sci 2019; 59:3984-3996. [PMID: 30098187 PMCID: PMC6082327 DOI: 10.1167/iovs.18-23885] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Purpose To study age- and intraocular pressure–induced changes in the glial lamina of the murine optic nerve on the ultrastructural level. Methods Naïve C57bl/6 mice at various ages spanning the time between early adulthood (3 months) and senescence (30 months) were used in this study. In addition, the intraocular pressure (IOP) was increased in a group of young mice by injection of microbeads into the anterior chamber. The unmyelinated segments of the optic nerve containing the glial lamina were prepared for transmission electron microscopy and imaged at high resolution. Results Axon packing density decreased slightly with age. Aging nerves contained higher numbers of enlarged and degenerating axons. Mean axonal diameter and in particular the variance of axonal diameter correlated well with age. Axonal mitochondria also showed age-dependent signs of pathology. The mean diameter of axonal mitochondria increased, and aged axons often contained profiles of mitochondria with very few or no cristae. Astrocytic mitochondria remained normal even in very old nerves. Changes to axons and axonal mitochondria in young glaucomatous nerves were comparable with those of 18- to 30-month-old naïve mice. In addition to axons and mitochondria, aged and glaucomatous nerves showed thickening of the blood vessel basement membranes and increased deposition of basement membrane collagen. Conclusions On the ultrastructural level, the effects of age and elevated IOP are quite similar. One month of elevated IOP seems to have as strongly detrimental effects on the nerve as at least 18 months of normal aging.
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Affiliation(s)
- Ying Zhu
- Department of Ophthalmology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, Hubei, China.,Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, Boston Massachusetts, United States
| | - Anthony C Pappas
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, Boston Massachusetts, United States
| | - Rui Wang
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, Boston Massachusetts, United States.,Department of Ophthalmology, The First Hospital of Xi'an, Xi'an, Shaanxi, China
| | - Philip Seifert
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, Boston Massachusetts, United States
| | - Daniel Sun
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, Boston Massachusetts, United States
| | - Tatjana C Jakobs
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, Boston Massachusetts, United States
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43
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Lozano DC, Choe TE, Cepurna WO, Morrison JC, Johnson EC. Early Optic Nerve Head Glial Proliferation and Jak-Stat Pathway Activation in Chronic Experimental Glaucoma. Invest Ophthalmol Vis Sci 2019; 60:921-932. [PMID: 30835784 PMCID: PMC6402265 DOI: 10.1167/iovs.18-25700] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 01/25/2019] [Indexed: 12/18/2022] Open
Abstract
PURPOSE We previously reported increased expression of cell proliferation and Jak-Stat pathway-related genes in chronic experimental glaucoma model optic nerve heads (ONH) with early, mild injury. Here, we confirm these observations by localizing, identifying, and quantifying ONH cellular proliferation and Jak-Stat pathway activation in this model. METHODS Chronic intraocular pressure (IOP) elevation was achieved via outflow pathway sclerosis. After 5 weeks, ONH longitudinal sections were immunolabeled with proliferation and cell-type markers to determine nuclear densities in the anterior (unmyelinated) and transition (partially myelinated) ONH. Nuclear pStat3 labeling was used to detect Jak-Stat pathway activation. Nuclear density differences between control ONH (uninjected) and ONH with either early or advanced injury (determined by optic nerve injury grading) were identified by ANOVA. RESULTS Advanced injury ONH had twice the nuclear density (P < 0.0001) of controls and significantly greater astrocyte density in anterior (P = 0.0001) and transition (P = 0.006) ONH regions. An increased optic nerve injury grade positively correlated with increased microglia/macrophage density in anterior and transition ONH (P < 0.0001, both). Oligodendroglial density was unaffected. In glaucoma model ONH, 80% of anterior and 66% of transition region proliferating cells were astrocytes. Nuclear pStat3 labeling significantly increased in early injury anterior ONH, and 95% colocalized with astrocytes. CONCLUSIONS Astrocytes account for the majority of proliferating cells, contributing to a doubled nuclear density in advanced injury ONH. Jak-Stat pathway activation is apparent in the early injury glaucoma model ONH. These data confirm dramatic astrocyte cell proliferation and early Jak-Stat pathway activation in ONH injured by elevated IOP.
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Affiliation(s)
- Diana C. Lozano
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Tiffany E. Choe
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - William O. Cepurna
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - John C. Morrison
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Elaine C. Johnson
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
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44
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Alqawlaq S, Flanagan JG, Sivak JM. All roads lead to glaucoma: Induced retinal injury cascades contribute to a common neurodegenerative outcome. Exp Eye Res 2018; 183:88-97. [PMID: 30447198 DOI: 10.1016/j.exer.2018.11.005] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 11/02/2018] [Accepted: 11/06/2018] [Indexed: 11/25/2022]
Abstract
Glaucoma describes a distinct optic neuropathy with complex etiology and a variety of associated risk factors, but with similar pathological endpoints. Risk factors such as age, increased intraocular pressure (IOP), low mean arterial pressure, and autoimmune disease, can all be associated with death of retinal ganglion cells (RGCs) and optic nerve head remodeling. Today, IOP management remains the standard of care, even though IOP elevation is not pathognomonic of glaucoma, and patients can continue to lose vision despite effective IOP control. A contemporary view of glaucoma as a complex, neurodegenerative disease has developed, along with the recognition of a need for new disease modifying retinal treatment strategies and improved outcomes. However, the distinction between risk factors triggering the disease process and retinal injury responses is not always clear. In this review, we attempt to distinguish between the various triggers, and their association with subsequent key RGC injury mechanisms. We propose that distinct glaucomatous risk factors result in similar retinal and optic nerve injury cascades, including oxidative and metabolic stress, glial reactivity, and altered inflammatory responses, which induce common molecular signals to induce RGC apoptosis. This organization forms a coherent disease framework and presents conserved targets for therapeutic intervention that are not limited to specific risk factors.
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Affiliation(s)
- Samih Alqawlaq
- Department of Vision Science, Krembil Research Institute, University Health Network, Toronto, ON, Canada; Vision Science Research Program, Ophthalmology and Vision Science, University of Toronto, Toronto, ON, Canada; Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - John G Flanagan
- School of Optometry and Vision Science Program, University of California at Berkeley, Berkeley, CA, USA
| | - Jeremy M Sivak
- Department of Vision Science, Krembil Research Institute, University Health Network, Toronto, ON, Canada; Vision Science Research Program, Ophthalmology and Vision Science, University of Toronto, Toronto, ON, Canada; Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
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45
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Guo C, Qu X, Rangaswamy N, Leehy B, Xiang C, Rice D, Prasanna G. A murine glaucoma model induced by rapid in vivo photopolymerization of hyaluronic acid glycidyl methacrylate. PLoS One 2018; 13:e0196529. [PMID: 29949582 PMCID: PMC6021085 DOI: 10.1371/journal.pone.0196529] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Accepted: 04/13/2018] [Indexed: 12/04/2022] Open
Abstract
Glaucoma is an optic neuropathy commonly associated with elevated intraocular pressure (IOP) resulting in progressive loss of retinal ganglion cells (RGCs) and optic nerve degeneration, leading to blindness. New therapeutic approaches that better preserve the visual field by promoting survival and health of RGCs are highly needed since RGC death occurs despite good IOP control in glaucoma patients. We have developed a novel approach to reliably induce chronic IOP elevation in mouse using a photopolymerizable biomatrix, hyaluronic acid glycidyl methacrylate. This is achieved by rapid in vivo crosslinking of the biomatrix at the iridocorneal angle by a flash of ultraviolet A (UVA) light to impede the aqueous outflow pathway with a controllable manner. Sustained IOP elevation was induced after a single manipulation and was maintained at ~45% above baseline for >4 weeks. Significant thinning of the inner retina and ~35% reduction in RGCs and axons was noted within one month of IOP elevation. Optic nerve degeneration showed positive correlation with cumulative IOP elevation. Activation of astrocytes and microglia appeared to be an early event in response to IOP elevation preceding detectable RGC and axon loss. Attenuated glial reactivity was noted at later stage where significant RGC/axon loss had occurred suggesting astrocytes and microglia may play different roles over the course of glaucomatous degeneration. This novel murine glaucoma model is reproducible and displays cellular changes that recapitulate several pathophysiological features of glaucoma.
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Affiliation(s)
- Chenying Guo
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, MA, United States of America
- * E-mail: (GP); (CG)
| | - Xin Qu
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, MA, United States of America
| | - Nalini Rangaswamy
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, MA, United States of America
| | - Barrett Leehy
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, MA, United States of America
| | - Chuanxi Xiang
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, MA, United States of America
| | - Dennis Rice
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, MA, United States of America
| | - Ganesh Prasanna
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, MA, United States of America
- * E-mail: (GP); (CG)
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Tehrani S, Delf RK, Cepurna WO, Davis L, Johnson EC, Morrison JC. In Vivo Small Molecule Delivery to the Optic Nerve in a Rodent Model. Sci Rep 2018. [PMID: 29535357 PMCID: PMC5849600 DOI: 10.1038/s41598-018-22737-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Small molecule delivery to the optic nerve would allow for exploration of molecular and cellular pathways involved in normal physiology and optic neuropathies such as glaucoma, and provide a tool for screening therapeutics in animal models. We report a novel surgical method for small molecule drug delivery to the optic nerve head (ONH) in a rodent model. In proof-of-principle experiments, we delivered cytochalasin D (Cyt D; a filamentous actin inhibitor) to the junction of the superior optic nerve and globe in rats to target the actin-rich astrocytic cytoskeleton of the ONH. Cyt D delivery was quantified by liquid chromatography and mass spectrometry of isolated optic nerve tissue. One day after Cyt D delivery, anterior ONH filamentous actin bundle content was significantly reduced as assessed by fluorescent-tagged phalloidin labeling, relative to sham delivery. Anterior ONH nuclear counts and axon-specific beta-3 tubulin levels, as well as peripapillary retinal ganglion cell layer nuclear counts were not significantly altered after Cyt D delivery relative to sham delivery. Lastly, the surgical delivery technique caused minimal observable axon degeneration up to 10 days post-surgery. This small molecule delivery technique provides a new approach to studying optic neuropathies in in vivo rodent models.
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Affiliation(s)
- Shandiz Tehrani
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA.
| | - R Katherine Delf
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
| | - William O Cepurna
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
| | - Lauren Davis
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
| | - Elaine C Johnson
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
| | - John C Morrison
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
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47
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Development of a Platform for Studying 3D Astrocyte Mechanobiology: Compression of Astrocytes in Collagen Gels. Ann Biomed Eng 2017; 46:365-374. [DOI: 10.1007/s10439-017-1967-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 11/21/2017] [Indexed: 12/25/2022]
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Albalawi F, Lu W, Beckel JM, Lim JC, McCaughey SA, Mitchell CH. The P2X7 Receptor Primes IL-1β and the NLRP3 Inflammasome in Astrocytes Exposed to Mechanical Strain. Front Cell Neurosci 2017; 11:227. [PMID: 28848393 PMCID: PMC5550720 DOI: 10.3389/fncel.2017.00227] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 07/19/2017] [Indexed: 11/13/2022] Open
Abstract
Inflammatory responses play a key role in many neural pathologies, with localized signaling from the non-immune cells making critical contributions. The NLRP3 inflammasome is an important component of innate immune signaling and can link neural insult to chronic inflammation. The NLRP3 inflammasome requires two stages to contribute: priming and activation. The priming stage involves upregulation of inflammasome components while the activation stage results in the assembly and activation of the inflammasome complex. The priming step can be rate limiting and can connect insult to chronic inflammation, but our knowledge of the signals that regulate NLRP3 inflammasome priming in sterile inflammation is limited. This study examined the link between mechanical strain and inflammasome priming in neural systems. Transient non-ischemic elevation of intraocular pressure increased mRNA for inflammasome components IL-1β, NLRP3, ASC, and CASP1 in rat and mouse retinas. The elevation was greater 1 day after the insult, with the rise in IL-1β most pronounced. The P2X7 receptor was implicated in the mechanosensitive priming of IL-1β mRNA in vivo, as the antagonist Brilliant Blue G (BBG) blocked the increased expression, the agonist BzATP mimicked the pressure-dependent rise in IL-1β, and the rise was absent in P2X7 knockout mice. In vitro measurements from optic nerve head astrocytes demonstrated an increased expression of IL-1β following stretch or swelling. This increase in IL-1β was eliminated by degradation of extracellular ATP with apyrase, or by the block of pannexin hemichannels with carbenoxolone, probenecid, or 10panx1 peptide. The rise in IL-1β expression was also blocked by P2X7 receptor antagonists BBG, A839977 or A740003. The rise in IL-1β was prevented by blocking transcription factor NFκB with Bay 11-7082, while the swelling-dependent fall in NFκB inhibitor IκB-α was reduced by A839977 and in P2X7 knockout mice. In summary, mechanical trauma to the retina primed NLRP3 inflammasome components, but only if there was ATP release through pannexin hemichannels, and autostimulation of the P2X7 receptor. As the P2X7 receptor can also trigger stage two of inflammasome assembly and activation, the P2X7 receptor may have a central role in linking mechanical strain to neuroinflammation.
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Affiliation(s)
- Farraj Albalawi
- Department of Anatomy and Cell Biology, University of Pennsylvania, PhiladelphiaPA, United States.,Department of Orthodontics, University of Pennsylvania, PhiladelphiaPA, United States
| | - Wennan Lu
- Department of Anatomy and Cell Biology, University of Pennsylvania, PhiladelphiaPA, United States
| | - Jonathan M Beckel
- Department of Anatomy and Cell Biology, University of Pennsylvania, PhiladelphiaPA, United States.,Department of Pharmacology and Chemical Biology, Pittsburgh University, PittsburghPA, United States
| | - Jason C Lim
- Department of Anatomy and Cell Biology, University of Pennsylvania, PhiladelphiaPA, United States
| | - Stuart A McCaughey
- Department of Anatomy and Cell Biology, University of Pennsylvania, PhiladelphiaPA, United States
| | - Claire H Mitchell
- Department of Anatomy and Cell Biology, University of Pennsylvania, PhiladelphiaPA, United States.,Department of Ophthalmology, University of Pennsylvania, PhiladelphiaPA, United States.,Department of Physiology, University of Pennsylvania, PhiladelphiaPA, United States
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Abstract
Mutations in the genes encoding the mechanosensitive cation channels PIEZO1 and PIEZO2 are responsible for multiple hereditary human diseases. Loss-of-function mutations in the human PIEZO1 gene cause autosomal recessive congenital lymphatic dysplasia. Gain-of-function mutations in the human PIEZO1 gene cause the autosomal dominant hemolytic anemia, hereditary xerocytosis (also known as dehydrated stomatocytosis). Loss-of-function mutations in the human PIEZO2 gene cause an autosomal recessive syndrome of muscular atrophy with perinatal respiratory distress, arthrogryposis, and scoliosis. Gain-of-function mutations in the human PIEZO2 gene cause three clinical types of autosomal dominant distal arthrogryposis. This chapter will review the hereditary diseases caused by mutations in the PIEZO genes and will discuss additional physiological systems in which PIEZO channel dysfunction may contribute to human disease pathophysiology.
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Affiliation(s)
- S L Alper
- Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, United States.
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