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Salkar A, Wall RV, Basavarajappa D, Chitranshi N, Parilla GE, Mirzaei M, Yan P, Graham S, You Y. Glial Cell Activation and Immune Responses in Glaucoma: A Systematic Review of Human Postmortem Studies of the Retina and Optic Nerve. Aging Dis 2024; 15:2069-2083. [PMID: 38502591 PMCID: PMC11346413 DOI: 10.14336/ad.2024.0103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 01/03/2024] [Indexed: 03/21/2024] Open
Abstract
Although researched extensively the understanding regarding mechanisms underlying glaucoma pathogenesis remains limited. Further, the exact mechanism behind neuronal death remains elusive. The role of neuroinflammation in retinal ganglion cell (RGC) death has been prominently theorised. This review provides a comprehensive summary of neuroinflammatory responses in glaucoma. A systematic search of Medline and Embase for articles published up to 8th March 2023 yielded 32 studies using post-mortem tissues from glaucoma patients. The raw data were extracted from tables and text to calculate the standardized mean differences (SMDs). These studies utilized post-mortem tissues from glaucoma patients, totalling 490 samples, compared with 380 control samples. Among the included studies, 27 reported glial cell activation based on changes to cellular morphology and molecular staining. Molecular changes were predominantly attributed to astrocytes (62.5%) and microglia (15.6%), with some involvement of Muller cells. These glial cell changes included amoeboid microglial cells with increased CD45 or HLA-DR intensity and hypertrophied astrocytes with increased glial fibrillary acidic protein labelling. Further, changes to extracellular matrix proteins like collagen, galectin, and tenascin-C suggested glial cells' influence on structural changes in the optic nerve head. The activation of DAMPs-driven immune response and the classical complement cascade was reported and found to be associated with activated glial cells in glaucomatous tissue. Increased pro-inflammatory markers such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were also linked to glial cells. Glial cell activation was also associated with mitochondrial, vascular, metabolic and antioxidant component disruptions. Association of the activated glial cells with pro-inflammatory responses, dysregulation of homeostatic components and antigen presentation indicates that glial cell responses influence glaucoma progression. However, the exact mechanism triggering these responses and underlying interactions remains unexplored. This necessitates further research using human samples for an increased understanding of the precise role of neuroinflammation in glaucoma progression.
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Affiliation(s)
- Akanksha Salkar
- Department of Clinical Medicine, Faculty of Human, Health, and Medical Science, Macquarie University. Sydney, NSW, Australia
| | - Roshana Vander Wall
- Department of Clinical Medicine, Faculty of Human, Health, and Medical Science, Macquarie University. Sydney, NSW, Australia
| | - Devaraj Basavarajappa
- Department of Clinical Medicine, Faculty of Human, Health, and Medical Science, Macquarie University. Sydney, NSW, Australia
| | - Nitin Chitranshi
- Department of Clinical Medicine, Faculty of Human, Health, and Medical Science, Macquarie University. Sydney, NSW, Australia
| | - Gabriella E Parilla
- Department of Clinical Medicine, Faculty of Human, Health, and Medical Science, Macquarie University. Sydney, NSW, Australia
| | - Mehdi Mirzaei
- Department of Clinical Medicine, Faculty of Human, Health, and Medical Science, Macquarie University. Sydney, NSW, Australia
| | - Peng Yan
- Department of Ophthalmology & Vision Sciences, University of Toronto, Kensington Eye Institute/UHN, Canada
| | - Stuart Graham
- Department of Clinical Medicine, Faculty of Human, Health, and Medical Science, Macquarie University. Sydney, NSW, Australia
| | - Yuyi You
- Department of Clinical Medicine, Faculty of Human, Health, and Medical Science, Macquarie University. Sydney, NSW, Australia
- Save Sight Institute, University of Sydney. Sydney, NSW, Australia
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Asrani SG, McGlumphy EJ, Al-Aswad LA, Chaya CJ, Lin S, Musch DC, Pitha I, Robin AL, Wirostko B, Johnson TV. The relationship between intraocular pressure and glaucoma: an evolving concept. Prog Retin Eye Res 2024:101303. [PMID: 39303763 DOI: 10.1016/j.preteyeres.2024.101303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 09/17/2024] [Accepted: 09/18/2024] [Indexed: 09/22/2024]
Abstract
Intraocular pressure (IOP) is the most important modifiable risk factor for glaucoma and fluctuates considerably within patients over short and long time periods. Our field's understanding of IOP has evolved considerably in recent years, driven by tonometric technologies with increasing accuracy, reproducibility, and temporal resolution that have refined our knowledge regarding the relationship between IOP and glaucoma risk and pathogenesis. The goal of this article is to review the published literature pertinent to the following points: 1) the factors that determine IOP in physiologic and pathologic states; 2) technologies for measuring IOP; 3) scientific and clinical rationale for measuring diverse IOP metrics in patients with glaucoma; 4) the impact and shortcomings of current standard-of-care IOP monitoring approaches; 5) recommendations for approaches to IOP monitoring that could improve patient outcomes; and 6) research questions that must be answered to improve our understanding of how IOP contributes to disease progression. Retrospective and prospective data, including that from landmark clinical trials, document greater IOP fluctuations in glaucomatous than healthy eyes, tendencies for maximal daily IOP to occur outside of office hours, and, in addition to mean and maximal IOP, an association between IOP fluctuation and glaucoma progression that is independent of mean in-office IOP. Ambulatory IOP monitoring, measuring IOP outside of office hours and at different times of day and night, provides clinicians with discrete data that could improve patient outcomes. Eye care clinicians treating glaucoma based on isolated in-office IOP measurements may make treatment decisions without fully capturing the entire IOP profile of an individual. Data linking home blood pressure monitors and home glucose sensors to dramatically improved outcomes for patients with systemic hypertension and diabetes and will be reviewed as they pertain to the question of whether ambulatory tonometry is positioned to do the same for glaucoma management. Prospective randomized controlled studies are warranted to determine whether remote tonometry-based glaucoma management might reduce vision loss and improve patient outcomes.
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Affiliation(s)
- Sanjay G Asrani
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, USA
| | | | - Lama A Al-Aswad
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Craig J Chaya
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Shan Lin
- Glaucoma Center of San Francisco, San Francisco, CA, USA
| | - David C Musch
- Department of Ophthalmology & Visual Sciences and Department of Epidemiology, Kellogg Eye Center, University of Michigan, Ann Arbor, MI, USA
| | - Ian Pitha
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Alan L Robin
- Department of Ophthalmology & Visual Sciences and Department of Epidemiology, Kellogg Eye Center, University of Michigan, Ann Arbor, MI, USA; Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Barbara Wirostko
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA.
| | - Thomas V Johnson
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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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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Kurokawa K, Nemeth M. Multifunctional adaptive optics optical coherence tomography allows cellular scale reflectometry, polarimetry, and angiography in the living human eye. BIOMEDICAL OPTICS EXPRESS 2024; 15:1331-1354. [PMID: 38404344 PMCID: PMC10890865 DOI: 10.1364/boe.505395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 01/15/2024] [Accepted: 01/16/2024] [Indexed: 02/27/2024]
Abstract
Clinicians are unable to detect glaucoma until substantial loss or dysfunction of retinal ganglion cells occurs. To this end, novel measures are needed. We have developed an optical imaging solution based on adaptive optics optical coherence tomography (AO-OCT) to discern key clinical features of glaucoma and other neurodegenerative diseases at the cellular scale in the living eye. Here, we test the feasibility of measuring AO-OCT-based reflectance, retardance, optic axis orientation, and angiogram at specifically targeted locations in the living human retina and optic nerve head. Multifunctional imaging, combined with focus stacking and global image registration algorithms, allows us to visualize cellular details of retinal nerve fiber bundles, ganglion cell layer somas, glial septa, superior vascular complex capillaries, and connective tissues. These are key histologic features of neurodegenerative diseases, including glaucoma, that are now measurable in vivo with excellent repeatability and reproducibility. Incorporating this noninvasive cellular-scale imaging with objective measurements will significantly enhance existing clinical assessments, which is pivotal in facilitating the early detection of eye disease and understanding the mechanisms of neurodegeneration.
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Affiliation(s)
- Kazuhiro Kurokawa
- Discoveries in Sight Research Laboratories, Devers Eye Institute, Legacy Research Institute, Legacy Health, Portland, OR 97232, USA
| | - Morgan Nemeth
- Discoveries in Sight Research Laboratories, Devers Eye Institute, Legacy Research Institute, Legacy Health, Portland, OR 97232, USA
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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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Hannay V, Czerpak CA, Quigley HA, Nguyen TD. A noninvasive clinical method to measure in vivo mechanical strains of the lamina cribrosa by optical coherence tomography. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.08.14.23294082. [PMID: 37645852 PMCID: PMC10462204 DOI: 10.1101/2023.08.14.23294082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Objective To measure mechanical strain of the lamina cribrosa (LC) after intraocular pressure (IOP) change produced one week after a change in glaucoma medication. Design Cohort study. Participants Adult glaucoma patients (23 eyes, 15 patients) prescribed a change in IOP-lowering medication. Intervention Non-invasive optical coherence tomography (OCT) imaging of the eye. Main Outcomes Deformation calculated by digital volume correlation of OCT scans of the LC before and after IOP lowering by medication. Results Among 23 eyes, 17 eyes of 12 persons had IOP lowering ≥ 3 mmHg (reduced IOP group) with tensile anterior-posterior E zz strain = 1.0% ± 1.1% (p = 0.003) and compressive radial strain ( E rr ) = -0.3% ± 0.5% (p=0.012; random effects models accounting inclusion of both eyes in some persons). Maximum in-plane principal (tensile) strain and maximum shear strain in the reduced IOP group were: E max = 1.7% ± 1.0% and Γ max = 1.4% ± 0.7%, respectively (both p<0.0001 versus zero). Reduced IOP group strains E max and Γ max were significantly larger with greater %IOP decrease (<0.0001, <0.0001). The compliance of the E zz , E max , and Γ max strain response, defined as strain normalized by the IOP decrease, were larger with more abnormal perimetric mean deviation or visual field index values (all p≥0.02). Strains were unrelated to age (all p≥0.088). In reduced IOP eyes, mean LC anterior border posterior movement was only 2.05 μm posteriorly (p=0.052) and not related to % IOP change (p=0.94, random effects models). Only E rr was significantly related to ALD change, becoming more negative with greater posterior LC border change (p=0.015). Conclusion LC mechanical strains can be effectively measured by changes in eye drop medication using OCT and are related to degree of visual function loss in glaucoma. Trial Registration ClinicalTrials.gov Identifier: NCT03267849.
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Waxman S, Quinn M, Donahue C, Falo LD, Sun D, Jakobs TC, Sigal IA. Individual astrocyte morphology in the collagenous lamina cribrosa revealed by multicolor DiOlistic labeling. Exp Eye Res 2023; 230:109458. [PMID: 36965593 PMCID: PMC10152998 DOI: 10.1016/j.exer.2023.109458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 03/17/2023] [Accepted: 03/20/2023] [Indexed: 03/27/2023]
Abstract
Astrocytes in the lamina region of the optic nerve head play vital roles in supporting retinal ganglion cell axon health. In glaucoma, these astrocytes are implicated as early responders to stressors, undergoing characteristic changes in cell function as well as cell morphology. Much of what is currently known about individual lamina astrocyte morphology has been learned from rodent models which lack a defining feature of the human optic nerve head, the collagenous lamina cribrosa (LC). Current methods available for evaluation of collagenous LC astrocyte morphology have significant shortcomings. We aimed to evaluate Multicolor DiOlistic labeling (MuDi) as an approach to reveal individual astrocyte morphologies across the collagenous LC. Gold microcarriers were coated with all combinations of three fluorescent cell membrane dyes, DiI, DiD, and DiO, for a total of seven dye combinations. Microcarriers were delivered to 150 μm-thick coronal vibratome slices through the LC of pig, sheep, goat, and monkey eyes via MuDi. Labeled tissues were imaged with confocal and second harmonic generation microscopy to visualize dyed cells and LC collagenous beams, respectively. GFAP labeling of DiOlistically-labeled cells with astrocyte morphologies was used to investigate cell identity. 3D models of astrocytes were created from confocal image stacks for quantification of morphological features. DiOlistic labeling revealed fine details of LC astrocyte morphologies including somas, primary branches, higher-order branches, and end-feet. Labeled cells with astrocyte morphologies were GFAP+. Astrocytes were visible across seven distinct color channels, allowing high labeling density while still distinguishing individual cells from their neighbors. MuDi was capable of revealing tens to hundreds of collagenous LC astrocytes, in situ, with a single application. 3D astrocyte models allowed automated quantification of morphological features including branch number, length, thickness, hierarchy, and straightness as well as Sholl analysis. MuDi labeling provides an opportunity to investigate morphologies of collagenous LC astrocytes, providing both qualitative and quantitative detail, in healthy tissues. This approach may open doors for research of glaucoma, where astrocyte morphological alterations are thought to coincide with key functional changes related to disease progression.
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Affiliation(s)
- Susannah Waxman
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Marissa Quinn
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Cara Donahue
- Department of Dermatology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Louis D Falo
- Department of Dermatology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Daniel Sun
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Tatjana C Jakobs
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Ian A Sigal
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA.
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