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Jing L, Liu K, Wang F, Su Y. Role of mechanically-sensitive cation channels Piezo1 and TRPV4 in trabecular meshwork cell mechanotransduction. Hum Cell 2024; 37:394-407. [PMID: 38316716 DOI: 10.1007/s13577-024-01035-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 01/17/2024] [Indexed: 02/07/2024]
Abstract
Glaucoma is one of the leading causes of irreversible blindness in developed countries, and intraocular pressure (IOP) is primary and only treatable risk factor, suggesting that to a significant extent, glaucoma is a disease of IOP disorder and pathological mechanotransduction. IOP-lowering ways are limited to decreaseing aqueous humour (AH) production or increasing the uveoscleral outflow pathway. Still, therapeutic approaches have been lacking to control IOP by enhancing the trabecular meshwork (TM) pathway. Trabecular meshwork cells (TMCs) have endothelial and myofibroblast properties and are responsible for the renewal of the extracellular matrix (ECM). Mechanosensitive cation channels, including Piezo1 and TRPV4, are abundantly expressed in primary TMCs and trigger mechanostress-dependent ECM and cytoskeletal remodelling. However, prolonged mechanical stimulation severely affects cellular biosynthesis through TMC mechanotransduction, including signaling, gene expression, ECM remodelling, and cytoskeletal structural changes, involving outflow facilities and elevating IOP. As for the functional coupling relationship between Piezo1 and TRPV4 channels, inspired by VECs and osteoblasts, we hypothesized that Piezo1 may also act upstream of TRPV4 in glaucomatous TM tissue, mediating the activation of TRPV4 via Ca2+ inflow or Ca2+ binding to phospholipase A2(PLA2), and thus be involved in increasing TM outflow resistance and elevated IOP. Therefore, this review aims to help identify new potential targets for IOP stabilization in ocular hypertension and primary open-angle glaucoma by understanding the mechanical transduction mechanisms associated with the development of glaucoma and may provide ideas into novel treatments for preventing the progression of glaucoma by targeting mechanotransduction.
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Affiliation(s)
- Lingling Jing
- Department of Ophthalmology, The Fourth Affiliated Hospital, Harbin Medical University, Harbin, China
| | - Kexin Liu
- Department of Ophthalmology, The Fourth Affiliated Hospital, Harbin Medical University, Harbin, China
| | - Feng Wang
- Department of Ophthalmology, The Fourth Affiliated Hospital, Harbin Medical University, Harbin, China.
| | - Ying Su
- Eye Hospital, The First Affiliated Hospital, Harbin Medical University, Harbin, China.
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2
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Hartmann A, Scholz I, Hoffmann EM, Strzalkowska A, Lackner KJ, Münzel T, Wicke FS, Schmidtmann I, Tüscher O, Schattenberg JM, Konstantinides S, Wild PS, Pfeiffer N, Schuster AK. Change of Intraocular Pressure Over 5 Years and its Relationship to Cardiovascular Parameters: Results From the Gutenberg Health Study. Invest Ophthalmol Vis Sci 2024; 65:12. [PMID: 38175640 PMCID: PMC10774695 DOI: 10.1167/iovs.65.1.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 11/12/2023] [Indexed: 01/05/2024] Open
Abstract
Purpose To investigate the longitudinal change in intraocular pressure (IOP) over 5 years and its relationship with cardiovascular parameters in a population-based sample in Germany. Methods The Gutenberg Health Study is a prospective, observational, single-center cohort study. The sample was equally stratified for sex, residence, and age decade. IOP was measured with noncontact tonometry at baseline and at 5-year follow-up. Cardiovascular parameters, including body mass index (BMI), systolic blood pressure, and diabetes status, were assessed. Participants without IOP measurement at one time point, who were taking IOP-lowering medications, or who had ophthalmic surgery during the 5-year follow-up interval were excluded, as well as those with glaucoma diagnosis. Univariable and multivariable linear regression analyses were conducted. Results This analysis included 9633 participants (48.9% female). The mean IOP increased from 14.04 ± 2.78 mmHg at baseline to 14.77 ± 2.92 mmHg at 5-year follow-up (P < 0.001). In multivariable linear regression analyses, an increase in BMI was associated with an increase in IOP over time (P < 0.001), whereas a higher baseline BMI was associated with a lower IOP change (P < 0.001). Higher age and male sex were associated with higher IOP change (P < 0.001). A change in systolic blood pressure was associated with IOP change, whereas baseline systolic blood pressure and diabetes status were not associated. Conclusions This population-based study found a relationship between IOP change over 5 years and BMI and systolic blood pressure change, respectively. These findings suggest the importance of monitoring cardiovascular risk factors in IOP management.
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Affiliation(s)
- Alica Hartmann
- Department of Ophthalmology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Ida Scholz
- Department of Ophthalmology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Esther M. Hoffmann
- Department of Ophthalmology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Alicja Strzalkowska
- Department of Ophthalmology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Karl J. Lackner
- Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Thomas Münzel
- Center for Cardiology–Cardiology I, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Felix S. Wicke
- Department of Psychosomatic Medicine and Psychotherapy, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Irene Schmidtmann
- Institute for Medical Biometry, Epidemiology and Informatics, Mainz, Germany
| | - Oliver Tüscher
- Institute of Molecular Biology, Mainz, Germany
- Clinic for Psychiatry and Psychotherapy, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
- Leibniz Institute for Resilience Research, Mainz, Germany
| | - Jörn M. Schattenberg
- Metabolic Liver Research Center and Medicine, University Medical Center, Mainz, Germany
| | | | - Philipp S. Wild
- Institute of Molecular Biology, Mainz, Germany
- Center for Thrombosis and Hemostasis, University Medical Center Mainz, Mainz, Germany
- Preventive Cardiology and Preventive Medicine, Department of Cardiology, University Medical Center Mainz, Mainz, Germany
- German Center for Cardiovascular Research (DZHK), partner site Rhine-Main, Mainz, Germany
| | - Norbert Pfeiffer
- Department of Ophthalmology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Alexander K. Schuster
- Department of Ophthalmology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
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Tan HY, Wu YF, Wang CY, Lin SJ, Ma YH, Young TH. The cellular responses of corneal fibroblasts to cyclic stretching loads. Exp Eye Res 2023; 237:109696. [PMID: 37890758 DOI: 10.1016/j.exer.2023.109696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 09/28/2023] [Accepted: 10/24/2023] [Indexed: 10/29/2023]
Abstract
Mechanical signaling plays a crucial role in maintaining extracellular matrix (ECM) homeostasis in various structures. In this study, we investigated the responses of corneal fibroblasts to cyclic stretching loads using an in vitro cell culture system. Bovine corneal fibroblasts were cultured and subjected to equibiaxial cyclic strain of 15% for 72 h at a frequency of 0.25 Hz, with bovine skin fibroblasts used as a comparison. We explored various cellular behaviors, including morphological changes, cell proliferation, and metabolism in response to mechanical stretching loads. The expression of genes, protein secretion, and enzymatic activity for several major metalloproteinases was also determined through Q-PCR, Western blot, and gel zymography. Additionally, we investigated the involvement of mitogen-activated protein kinases (MAPKs) signaling pathways in the corneal fibroblasts when subjected to mechanical stimuli. Our findings revealed that, compared to skin fibroblasts, corneal fibroblasts were reluctant to morphological changes in response to a prolonged (72 h) and high-amplitude (15% of strain) cyclic stretching load. However, cyclic stretching loads stimulated the upregulation of MMP-2 expression in corneal fibroblasts via the MAPK signaling pathways involving extracellular signal-regulated kinase and p38. Together with a lack of upregulation in type I collagen expression, our results indicate the induction of the ECM degradation process in corneal fibroblasts in response to cyclic stretching. These findings emphasize the mechanoresponsive nature of corneal fibroblasts and shed light on the potential impact of intense mechanical stress on the cornea in both normal and pathological conditions such as keratoconus, providing valuable insights for understanding corneal mechanobiology.
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Affiliation(s)
- Hsin-Yuan Tan
- Department of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei, Taiwan; Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou, Taiwan; College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Yueh-Feng Wu
- Department of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei, Taiwan
| | - Chia-Yi Wang
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Sung-Jan Lin
- Department of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei, Taiwan; Department of Dermatology, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan; Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, Taiwan; Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan; Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yunn-Hwa Ma
- Department of Physiology and Pharmacology and Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan
| | - Tai-Horng Young
- Department of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei, Taiwan.
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4
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Karimi A, Crouch DJ, Razaghi R, Crawford Downs J, Acott TS, Kelley MJ, Behnsen JG, Bosworth LA, Sheridan CM. Morphological and biomechanical analyses of the human healthy and glaucomatous aqueous outflow pathway: Imaging-to-modeling. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 236:107485. [PMID: 37149973 DOI: 10.1016/j.cmpb.2023.107485] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/09/2023] [Accepted: 03/13/2023] [Indexed: 05/09/2023]
Abstract
BACKGROUND AND OBJECTIVE Intraocular pressure (IOP) is maintained via a dynamic balance between the production of aqueous humor and its drainage through the trabecular meshwork (TM), juxtacanalicular connective tissue (JCT), and Schlemm's canal (SC) endothelium of the conventional outflow pathway. Primary open angle glaucoma (POAG) is often associated with IOP elevation that occurs due to an abnormally high outflow resistance across the outflow pathway. Outflow tissues are viscoelastic and actively interact with aqueous humor dynamics through a two-way fluid-structure interaction coupling. While glaucoma affects the morphology and stiffness of the outflow tissues, their biomechanics and hydrodynamics in glaucoma eyes remain largely unknown. This research aims to develop an image-to-model method allowing the biomechanics and hydrodynamics of the conventional aqueous outflow pathway to be studied. METHODS We used a combination of X-ray computed tomography and scanning electron microscopy to reconstruct high-fidelity, eye-specific, 3D microstructural finite element models of the healthy and glaucoma outflow tissues in cellularized and decellularized conditions. The viscoelastic TM/JCT/SC complex finite element models with embedded viscoelastic beam elements were subjected to a physiological IOP load boundary; the stresses/strains and the flow state were calculated using fluid-structure interaction and computational fluid dynamics. RESULTS Based on the resultant hydrodynamics parameters across the outflow pathway, the primary site of outflow resistance in healthy eyes was in the JCT and immediate vicinity of the SC inner wall, while the majority of the outflow resistance in the glaucoma eyes occurred in the TM. The TM and JCT in the glaucoma eyes showed 1.32-fold and 1.13-fold larger beam thickness and smaller trabecular space size (2.24-fold and 1.50-fold) compared to the healthy eyes. CONCLUSIONS Characterizing the accurate morphology of the outflow tissues may significantly contribute to constructing more accurate, robust, and reliable models, that can eventually help to better understand the dynamic IOP regulation, hydrodynamics of the aqueous humor, and outflow resistance dynamic in the human eyes. This model demonstrates proof of concept for determining changes to outflow resistance in healthy and glaucomatous tissues and thus may be utilized in larger cohorts of donor tissues where disease specificity, race, age, and gender of the eye donors may be accounted for.
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Affiliation(s)
- Alireza Karimi
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Devon J Crouch
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L7 8TX, United Kingdom
| | - Reza Razaghi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, United States
| | - J Crawford Downs
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Ted S Acott
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States; Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon, United States
| | - Mary J Kelley
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States; Department of Integrative Biosciences, Oregon Health & Science University, Portland, Oregon, United States
| | - Julia G Behnsen
- Department of Mechanical, Materials, and Aerospace Engineering, University of Liverpool, Liverpool, L69 6GB, United Kingdom
| | - Lucy A Bosworth
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L7 8TX, United Kingdom
| | - Carl M Sheridan
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L7 8TX, United Kingdom.
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Ren R, Humphrey AA, Kopczynski C, Gong H. Rho Kinase Inhibitor AR-12286 Reverses Steroid-Induced Changes in Intraocular Pressure, Effective Filtration Areas, and Morphology in Mouse Eyes. Invest Ophthalmol Vis Sci 2023; 64:7. [PMID: 36734964 PMCID: PMC9907372 DOI: 10.1167/iovs.64.2.7] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Accepted: 01/11/2023] [Indexed: 02/04/2023] Open
Abstract
Purpose We investigated mechanisms of reduction of intraocular pressure (IOP) by Rho kinase inhibitor AR-12286 in steroid-induced ocular hypertension (SIOH). Methods C57BL/6 mice (N = 56) were randomly divided into Saline, dexamethasone (DEX), DEX + AR-12286, and DEX-discontinuation (DEX-DC) groups. IOP was measured weekly during the first four weeks in all groups. Beginning at week 5, the DEX-DC group was followed without treatment until IOP returned to normal, and the other groups were treated as assigned with IOP measured every other day for another week. Fluorescent tracer was injected into the anterior chamber to visualize the outflow pattern in the trabecular meshwork (TM) and TM effective filtration area (EFA) was determined. Radial sections from both high- and low-tracer regions were processed for electron microscopy. Results AR-12286 reduced IOP in SIOH mouse eyes in one day (P < 0.01). At the end of week 5, mean IOP in the DEX + AR-12286 group was ∼4 mm Hg lower than DEX group (P < 0.001) and ∼2 mm Hg lower than DEX-DC group (P < 0.05). After one-week AR-12286 treatment (P < 0.05) or five-week DC of DEX (P < 0.01), DEX-induced reduction of EFA was rescued and DEX-induced morphological changes in the TM were partially reversed. Conclusions AR-12286 reversed steroid-induced morphological changes in the TM and reduced EFA, which correlated with reduced IOP in SIOH eyes. AR-12286 reduced IOP elevation in SIOH eyes more effectively than discontinuing DEX treatment even when accompanied by continuous DEX treatment. Therefore Rho kinase inhibitors may lower SIOH in patients who rely on steroid treatment.
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Affiliation(s)
- Ruiyi Ren
- Boston University School of Medicine, Department of Ophthalmology, Boston, Massachusetts, United States
| | - Anne A. Humphrey
- Boston University School of Medicine, Department of Ophthalmology, Boston, Massachusetts, United States
| | - Casey Kopczynski
- Aerie Pharmaceuticals, Inc., Durham, North Carolina, United States
| | - Haiyan Gong
- Boston University School of Medicine, Department of Ophthalmology, Boston, Massachusetts, United States
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Adulla A, Patel U, Ashok A, Katiyar P, Kaulakis M, Kritikos AE, Pillai S, Lee H, Lindner E, Rhee DJ, Singh N. α-Synuclein modulates fibronectin expression in the trabecular meshwork independent of TGFβ2. Exp Eye Res 2023; 226:109351. [PMID: 36539052 PMCID: PMC10384565 DOI: 10.1016/j.exer.2022.109351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 12/06/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022]
Abstract
α-Synuclein (α-Syn) is implicated in Parkinson's disease (PD), a neuromotor disorder with prominent visual symptoms. The underlying cause of motor dysfunction has been studied extensively, and is attributed to the death of dopaminergic neurons mediated in part by intracellular aggregation of α-Syn. The cause of visual symptoms, however, is less clear. Neuroretinal degeneration due to the presence of aggregated α-Syn has been reported, but the evidence is controversial. Other symptoms including those arising from primary open angle glaucoma (POAG) are believed to be the side-effects of medications prescribed for PD. Here, we explored the alternative hypothesis that dysfunction of α-Syn in the anterior eye alters the interaction between the actin cytoskeleton of trabecular meshwork (TM) cells with the extracellular matrix (ECM), impairing their ability to respond to physiological changes in intraocular pressure (IOP). A similar dysfunction in neurons is responsible for impaired neuritogenesis, a characteristic feature of PD. Using cadaveric human and bovine TM tissue and primary human TM cells as models, we report two main observations: 1) α-Syn is expressed in human and bovine TM cells, and significant amounts of monomeric and oligomeric α-Syn are present in the AH, and 2) primary human TM cells and human and bovine TM tissue endocytose extracellular recombinant monomeric and oligomeric α-Syn via the prion protein (PrPC), and upregulate fibronectin (FN) and α-smooth muscle actin (α-SMA), fibrogenic proteins implicated in POAG. Transforming growth factor β2 (TGFβ2), a fibrogenic cytokine implicated in ∼50% cases of POAG, is also increased, and so is RhoA-associated coiled-coil-containing protein kinase 1 (ROCK-1). However, silencing of α-Syn in primary human TM cells reduces FN, α-SMA, and ROCK-1 in the absence or presence of over-expressed active TGFβ2, suggesting modulation of FN and ROCK-1 independent of, or upstream of TGFβ2. These observations suggest that extracellular α-Syn modulates ECM proteins in the TM independently or via PrPC by activating the RhoA-ROCK pathway. These observations reveal a novel function of α-Syn in the anterior eye, and offer new therapeutic options.
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Affiliation(s)
- Anika Adulla
- Departments of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Urvi Patel
- Departments of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Ajay Ashok
- Departments of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Priya Katiyar
- Departments of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Mare Kaulakis
- Departments of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Alexander E Kritikos
- Departments of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Sachin Pillai
- Departments of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - HyunPin Lee
- Departments of Ophthalmology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Ewald Lindner
- Department of Ophthalmology, Medical University of Graz, Auenbruggerplatz 4, 8036, Graz, Austria
| | - Douglas J Rhee
- Departments of Ophthalmology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Neena Singh
- Departments of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA.
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7
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Karimi A, Razaghi R, Rahmati SM, Downs JC, Acott TS, Kelley MJ, Wang RK, Johnstone M. The Effect of Intraocular Pressure Load Boundary on the Biomechanics of the Human Conventional Aqueous Outflow Pathway. Bioengineering (Basel) 2022; 9:672. [PMID: 36354583 PMCID: PMC9687513 DOI: 10.3390/bioengineering9110672] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 10/28/2022] [Accepted: 11/08/2022] [Indexed: 09/29/2023] Open
Abstract
BACKGROUND Aqueous humor outflow resistance in the trabecular meshwork (TM), juxtacanalicular connective tissue (JCT), and Schlemm's canal (SC) endothelium of the conventional outflow pathway actively contribute to intraocular pressure (IOP) regulation. Outflow resistance is actively affected by the dynamic outflow pressure gradient across the TM, JCT, and SC inner wall tissues. The resistance effect implies the presence of a fluid-structure interaction (FSI) coupling between the outflow tissues and the aqueous humor. However, the biomechanical interactions between viscoelastic outflow tissues and aqueous humor dynamics are largely unknown. METHODS A 3D microstructural finite element (FE) model of a healthy human eye TM/JCT/SC complex was constructed with elastic and viscoelastic material properties for the bulk extracellular matrix and embedded elastic cable elements. The FE models were subjected to both idealized and a physiologic IOP load boundary using the FSI method. RESULTS The elastic material model for both the idealized and physiologic IOP load boundary at equal IOPs showed similar stresses and strains in the outflow tissues as well as pressure in the aqueous humor. However, outflow tissues with viscoelastic material properties were sensitive to the IOP load rate, resulting in different mechanical and hydrodynamic responses in the tissues and aqueous humor. CONCLUSIONS Transient IOP fluctuations may cause a relatively large IOP difference of ~20 mmHg in a very short time frame of ~0.1 s, resulting in a rate stiffening in the outflow tissues. Rate stiffening reduces strains and causes a rate-dependent pressure gradient across the outflow tissues. Thus, the results suggest it is necessary to use a viscoelastic material model in outflow tissues that includes the important role of IOP load rate.
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Affiliation(s)
- Alireza Karimi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Reza Razaghi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | | | - J. Crawford Downs
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Ted S. Acott
- Departments of Ophthalmology and Biochemistry and Molecular Biology, Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Mary J. Kelley
- Departments of Ophthalmology and Integrative Biosciences, Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Ruikang K. Wang
- Department of Ophthalmology, University of Washington, Seattle, WA 98195, USA
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Murray Johnstone
- Department of Ophthalmology, University of Washington, Seattle, WA 98195, USA
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8
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Karimi A, Razaghi R, Padilla S, Rahmati SM, Downs JC, Acott TS, Kelley MJ, Wang RK, Johnstone M. Viscoelastic Biomechanical Properties of the Conventional Aqueous Outflow Pathway Tissues in Healthy and Glaucoma Human Eyes. J Clin Med 2022; 11:6049. [PMID: 36294371 PMCID: PMC9605362 DOI: 10.3390/jcm11206049] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 10/11/2022] [Accepted: 10/12/2022] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Although the tissues comprising the ocular conventional outflow pathway have shown strong viscoelastic mechanical response to aqueous humor pressure dynamics, the viscoelastic mechanical properties of the trabecular meshwork (TM), juxtacanalicular connective tissue (JCT), and Schlemm's canal (SC) inner wall are largely unknown. METHODS A quadrant of the anterior segment from two human donor eyes at low- and high-flow (LF and HF) outflow regions was pressurized and imaged using optical coherence tomography (OCT). A finite element (FE) model of the TM, the adjacent JCT, and the SC inner wall was constructed and viscoelastic beam elements were distributed in the extracellular matrix (ECM) of the TM and JCT to represent anisotropic collagen. An inverse FE-optimization algorithm was used to calculate the viscoelastic properties of the ECM/beam elements such that the TM/JCT/SC model and OCT imaging data best matched over time. RESULTS The ECM of the glaucoma tissues showed significantly larger time-dependent shear moduli compared to the heathy tissues. Significantly larger shear moduli were also observed in the LF regions of both the healthy and glaucoma eyes compared to the HF regions. CONCLUSIONS The outflow tissues in both glaucoma eyes and HF regions are stiffer and less able to respond to dynamic IOP.
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Affiliation(s)
- Alireza Karimi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Reza Razaghi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Steven Padilla
- Department of Ophthalmology, University of Washington, Seattle, WA 98109, USA
| | | | - J. Crawford Downs
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Ted S. Acott
- Departments of Ophthalmology and Biochemistry and Molecular Biology, Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Mary J. Kelley
- Departments of Ophthalmology and Integrative Biosciences, Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Ruikang K. Wang
- Department of Ophthalmology, University of Washington, Seattle, WA 98109, USA
- Department of Bioengineering, University of Washington, Seattle, WA 98105, USA
| | - Murray Johnstone
- Department of Ophthalmology, University of Washington, Seattle, WA 98109, USA
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9
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Soundararajan A, Wang T, Sundararajan R, Wijeratne A, Mosley A, Harvey FC, Bhattacharya S, Pattabiraman PP. Multiomics analysis reveals the mechanical stress-dependent changes in trabecular meshwork cytoskeletal-extracellular matrix interactions. Front Cell Dev Biol 2022; 10:874828. [PMID: 36176278 PMCID: PMC9513235 DOI: 10.3389/fcell.2022.874828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Accepted: 08/12/2022] [Indexed: 11/29/2022] Open
Abstract
Trabecular meshwork (TM) tissue is subjected to constant mechanical stress due to the ocular pulse created by the cardiac cycle. This brings about alterations in the membrane lipids and associated cell–cell adhesion and cell–extracellular matrix (ECM) interactions, triggering intracellular signaling responses to counter mechanical insults. A loss of such response can lead to elevated intraocular pressure (IOP), a major risk factor for primary open-angle glaucoma. This study is aimed to understand the changes in signaling responses by TM subjected to mechanical stretch. We utilized multiomics to perform an unbiased mRNA sequencing to identify changes in transcripts, mass spectrometry- (MS-) based quantitative proteomics for protein changes, and multiple reaction monitoring (MRM) profiling-based MS and high-performance liquid chromatography (HPLC-) based MS to characterize the lipid changes. We performed pathway analysis to obtain an integrated map of TM response to mechanical stretch. The human TM cells subjected to mechanical stretch demonstrated an upregulation of protein quality control, oxidative damage response, pro-autophagic signal, induction of anti-apoptotic, and survival signaling. We propose that mechanical stretch-induced lipid signaling via increased ceramide and sphingomyelin potentially contributes to increased TM stiffness through actin-cytoskeleton reorganization and profibrotic response. Interestingly, increased phospholipids and diacylglycerol due to mechanical stretch potentially enable cell membrane remodeling and changes in signaling pathways to alter cellular contractility. Overall, we propose the mechanistic interplay of macromolecules to bring about a concerted cellular response in TM cells to achieve mechanotransduction and IOP regulation when TM cells undergo mechanical stretch.
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Affiliation(s)
- Avinash Soundararajan
- Department of Ophthalmology, Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Ting Wang
- Department of Ophthalmology, Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN, United States
- Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Rekha Sundararajan
- Department of Ophthalmology, Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Aruna Wijeratne
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
- Center for Proteome Analysis, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Amber Mosley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
- Center for Proteome Analysis, Indiana University School of Medicine, Indianapolis, IN, United States
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Faith Christine Harvey
- Bascom Palmer Eye Institute, Miller School of Medicine at University of Miami, Miami, FL, United States
- Miami Integrative Metabolomics Research Center, Miami, FL, United States
| | - Sanjoy Bhattacharya
- Bascom Palmer Eye Institute, Miller School of Medicine at University of Miami, Miami, FL, United States
- Miami Integrative Metabolomics Research Center, Miami, FL, United States
| | - Padmanabhan Paranji Pattabiraman
- Department of Ophthalmology, Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN, United States
- Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, IN, United States
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
- *Correspondence: Padmanabhan Paranji Pattabiraman,
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10
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Chen S, Wang W, Cao Q, Wu S, Wang N, Ji L, Zhu W. Cationic Mechanosensitive Channels Mediate Trabecular Meshwork Responses to Cyclic Mechanical Stretch. Front Pharmacol 2022; 13:881286. [PMID: 35928263 PMCID: PMC9343793 DOI: 10.3389/fphar.2022.881286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 06/23/2022] [Indexed: 11/13/2022] Open
Abstract
The trabecular meshwork (TM) is responsible for intraocular pressure (IOP) homeostasis in the eye. The tissue senses IOP fluctuations and dynamically adapts to the mechanical changes to either increase or decrease aqueous humor outflow. Cationic mechanosensitive channels (CMCs) have been reported to play critical roles in mediating the TM responses to mechanical forces. However, how CMCs influence TM cellular function affect aqueous humor drainage is still elusive. In this study, human TM (HTM) cells were collected from a Chinese donor and subjected to cyclically equiaxial stretching with an amplitude of 20% at 1 Hz GsMTx4, a non-selective inhibitor for CMCs, was added to investigate the proteomic changes induced by CMCs in response to mechanical stretch of HTM. Gene ontology enrichment analysis demonstrated that inhibition of CMCs significantly influenced several biochemical pathways, including store-operated calcium channel activity, microtubule cytoskeleton polarity, toll-like receptor signaling pathway, and neuron cell fate specification. Through heatmap analysis, we grouped 148 differentially expressed proteins (DEPs) into 21 clusters and focused on four specific patterns associated with Ca2+ homeostasis, autophagy, cell cycle, and cell fate. Our results indicated that they might be the critical downstream signals of CMCs adapting to mechanical forces and mediating AH outflow.
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Affiliation(s)
- Susu Chen
- School of Pharmacy, Qingdao University, Qingdao, China
| | - Wenyan Wang
- Department of Clinical Pharmacy, The Second Hospital of Traditional Chinese Medicine of Huangdao District, Qingdao, China
| | - Qilong Cao
- Qingdao Haier Biotech Co.,Ltd., Qingdao, China
| | - Shen Wu
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Capital Medical University, Beijing, China
| | - Ningli Wang
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Capital Medical University, Beijing, China
| | - Lixia Ji
- School of Pharmacy, Qingdao University, Qingdao, China
- *Correspondence: Wei Zhu, ; Lixia Ji,
| | - Wei Zhu
- School of Pharmacy, Qingdao University, Qingdao, China
- Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beihang University and Capital Medical University, Beijing, China
- *Correspondence: Wei Zhu, ; Lixia Ji,
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11
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Chen Y, Su Y, Wang F. The Piezo1 ion channel in glaucoma: a new perspective on mechanical stress. Hum Cell 2022; 35:1307-1322. [PMID: 35767143 DOI: 10.1007/s13577-022-00738-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 06/13/2022] [Indexed: 11/26/2022]
Abstract
Glaucomatous optic nerve damage caused by pathological intraocular pressure elevation is irreversible, and its course is often difficult to control. This group of eye diseases is closely related to biomechanics, and the correlation between glaucoma pathogenesis and mechanical stimulation has been studied in recent decades. The nonselective cation channel Piezo1, the most important known mechanical stress sensor, is a transmembrane protein widely expressed in various cell types. Piezo1 has been detected throughout the eye, and the close relationship between Piezo1 and glaucoma is being confirmed. Pathological changes in glaucoma occur in both the anterior and posterior segments of the eye, and it is of great interest for researchers to determine whether Piezo1 plays a role in these changes and how it functions. The elucidation of the mechanisms of Piezo1 action in nonocular tissues and the reported roles of similar mechanically activated ion channels in glaucoma will provide an appropriate basis for further investigation. From a new perspective, this review provides a detailed description of the current progress in elucidating the role of Piezo1 in glaucoma, including relevant questions and assumptions, the remaining challenging research directions and mechanism-related therapeutic potential.
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Affiliation(s)
- Yidan Chen
- Department of Ophthalmology, Fourth Affiliated Hospital, Harbin Medical University, Yiyuan Road, Harbin, 150001, China
| | - Ying Su
- Eye Hospital, First Affiliated Hospital, Harbin Medical University, Yiman Road, Harbin, 150007, China.
| | - Feng Wang
- Department of Ophthalmology, Fourth Affiliated Hospital, Harbin Medical University, Yiyuan Road, Harbin, 150001, China.
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12
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YAP/TAZ Promote Fibrotic Activity in Human Trabecular Meshwork Cells by Sensing Cytoskeleton Structure Alternation. CHEMOSENSORS 2022. [DOI: 10.3390/chemosensors10070235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Trabecular meshwork (TM) is the main channel of aqueous humor (AH) outflow and the crucial tissue responsible for intraocular pressure (IOP) regulation. The aberrant fibrotic activity of human TM (HTM) cells is thought to be partially responsible for the increased resistance to AH outflow and elevated IOP. This study aimed to identify the TM cell fibrotic activity biomarker and illustrate the mechanisms of fibrotic activity regulation in HTM cells. We used TGFβ2-treated HTM cells and detected the changes in the cytoskeletal structure, the Yes-associated protein (YAP) and its transcriptional co-activator with PDZ-binding domain (TAZ) activation, and the expression levels of the fibrosis-related proteins Collagen I and α-SMA in HTM cells by immunofluorescence staining or western bolt analyses. The expression of YAP was inhibited using siRNA transfection. The results showed that the expression levels of YAP/TAZ and the fibrosis-related proteins Collagen I and α-SMA in HTM cells were elevated under TGF-β2 treatment, which was correlated with the structural change of the cellular F-actin cytoskeleton. Furthermore, the inhibition of YAP decreased the expression of connective tissue growth factor (CTGF), Collagen I, and α-SMA in HTM cells. These findings demonstrate that YAP/TAZ are potential biomarkers in evaluating the TM cell fibrotic activity, and it could sense cytoskeletal structure cues and regulate the fibrotic activity of TM cells.
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13
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Karimi A, Razaghi R, Rahmati SM, Downs JC, Acott TS, Wang RK, Johnstone M. Modeling the biomechanics of the conventional aqueous outflow pathway microstructure in the human eye. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 221:106922. [PMID: 35660940 PMCID: PMC10424784 DOI: 10.1016/j.cmpb.2022.106922] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/16/2022] [Accepted: 05/26/2022] [Indexed: 05/27/2023]
Abstract
BACKGROUND AND OBJECTIVE Intraocular pressure (IOP) is determined by aqueous humor outflow resistance, which is a function of the combined resistance of Schlemm's canal (SC) endothelium and the trabecular meshwork (TM) and their interactions in the juxtacanalicular connective tissue (JCT) region. Aqueous outflow in the conventional outflow pathway results in pressure gradient across the TM, JCT, and SC inner wall, and induces mechanical stresses and strains that influence the geometry and homeostasis of the outflow system. The outflow resistance is affected by alteration in tissues' geometry, so there is potential for active, two-way, fluid-structure interaction (FSI) coupling between the aqueous humor (fluid) and the TM, JCT, and SC inner wall (structure). However, our understanding of the biomechanical interactions of the aqueous humor with the outflow connective tissues and its contribution to the outflow resistance regulation is incomplete. METHODS In this study, a microstructural finite element (FE) model of a human eye TM, JCT, and SC inner wall was constructed from a segmented, high-resolution histologic 3D reconstruction of the human outflow system. Three different elastic moduli (0.004, 0.128, and 51.5 MPa based on prior reports) were assigned to the TM/JCT complex while the elastic modulus of the SC inner wall was kept constant at 0.00748 MPa. The hydraulic conductivity was programmed separately for the TM, JCT, and SC inner wall using a custom subroutine. Cable elements were embedded into the TM and JCT extracellular matrix to represent the directional stiffness imparted by anisotropic collagen fibril orientation. The resultant stresses and strains in the outflow system were calculated using fluid-structure interaction method. RESULTS The higher TM/JCT stiffness resulted in larger stresses, but smaller strains in the outflow connective tissues, and resulted in a 4- and 5-fold larger pressure drop across the SC inner wall, respectively, compared to the most compliant model. Funneling through µm-sized SC endothelial pores was evident in the models at lower tissue stiffness, but aqueous flow was more turbulent in models with higher TM/JCT stiffness. CONCLUSIONS The mechanical properties of the outflow tissues play a crucial role in the hydrodynamics of the aqueous humor in the conventional outflow system.
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Affiliation(s)
- Alireza Karimi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, 1670 University Boulevard, VH 372B, Birmingham, AL 35294, USA.
| | - Reza Razaghi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, 1670 University Boulevard, VH 372B, Birmingham, AL 35294, USA
| | | | - J Crawford Downs
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, 1670 University Boulevard, VH 372B, Birmingham, AL 35294, USA
| | - Ted S Acott
- Ophthalmology and Biochemistry and Molecular Biology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Ruikang K Wang
- Department of Ophthalmology, University of Washington, Seattle, WA, USA; Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Murray Johnstone
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
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14
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De Ieso ML, Kuhn M, Bernatchez P, Elliott MH, Stamer WD. A Role of Caveolae in Trabecular Meshwork Mechanosensing and Contractile Tone. Front Cell Dev Biol 2022; 10:855097. [PMID: 35372369 PMCID: PMC8969750 DOI: 10.3389/fcell.2022.855097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 03/03/2022] [Indexed: 11/13/2022] Open
Abstract
Polymorphisms in the CAV1/2 gene loci impart increased risk for primary open-angle glaucoma (POAG). CAV1 encodes caveolin-1 (Cav1), which is required for biosynthesis of plasma membrane invaginations called caveolae. Cav1 knockout mice exhibit elevated intraocular pressure (IOP) and decreased outflow facility, but the mechanistic role of Cav1 in IOP homeostasis is unknown. We hypothesized that caveolae sequester/inhibit RhoA, to regulate trabecular meshwork (TM) mechanosensing and contractile tone. Using phosphorylated myosin light chain (pMLC) as a surrogate indicator for Rho/ROCK activity and contractile tone, we found that pMLC was elevated in Cav1-deficient TM cells compared to control (131 ± 10%, n = 10, p = 0.016). Elevation of pMLC levels following Cav1 knockdown occurred in cells on a soft surface (137 ± 7%, n = 24, p < 0.0001), but not on a hard surface (122 ± 17%, n = 12, p = 0.22). In Cav1-deficient TM cells where pMLC was elevated, Rho activity was also increased (123 ± 7%, n = 6, p = 0.017), suggesting activation of the Rho/ROCK pathway. Cyclic stretch reduced pMLC/MLC levels in TM cells (69 ± 7% n = 9, p = 0.002) and in Cav1-deficient TM cells, although not significantly (77 ± 11% n = 10, p = 0.059). Treatment with the Cav1 scaffolding domain mimetic, cavtratin (1 μM) caused a reduction in pMLC (70 ± 5% n = 7, p = 0.001), as did treatment with the scaffolding domain mutant cavnoxin (1 μM) (82 ± 7% n = 7, p = 0.04). Data suggest that caveolae differentially regulate RhoA signaling, and that caveolae participate in TM mechanotransduction. Cav1 regulation of these key TM functions provide evidence for underlying mechanisms linking polymorphisms in the Cav1/2 gene loci with increased POAG risk.
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Affiliation(s)
- Michael L. De Ieso
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, United States
| | - Megan Kuhn
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, United States
| | - Pascal Bernatchez
- Department of Anesthesiology, Pharmacology and Therapeutics, Faculty of Medicine, University of British Columbia, Heart + Lung Innovation Centre, St. Paul’s Hospital, Vancouver, BC, Canada
| | - Michael H. Elliott
- Department of Ophthalmology, Dean McGee Eye Institute University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - W. Daniel Stamer
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, United States
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15
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Liao N, Xie YQ, Mao GY, Bao FJ, Lin Z, Jiang HL, Liang YB. Observation seasonal variation of intraocular pressure in young healthy volunteers. Int J Ophthalmol 2022; 15:59-64. [PMID: 35047357 DOI: 10.18240/ijo.2022.01.09] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 12/19/2020] [Indexed: 11/23/2022] Open
Abstract
AIM To investigate fluctuation of intraocular pressure (IOP) and seasonal variation of 24-hour IOP during one year in healthy participants. METHODS Totally 13 young healthy volunteers participated in this study. IOP was measured with Canon TX-20 at about 8:00-9:00 a.m. from Monday to Friday every week for a whole year. They also underwent 24-hour IOP examination every three months. Blood pressure, heart rate, temperature, humidity, atmosphere pressure, sunshine duration and other environment parameters were recorded. RESULTS The yearly fluctuation curve showed IOP in the summer months were lower than other seasons. In the multivariable generalized estimating equation analysis, IOP had a negative correlation with both temperature and sunshine duration (P<0.05). There also was a seasonal effect on 24-hour IOP. However, all intraclass correlation coefficients values of minimum, maximum and average of the 24-hour IOP and each individual IOP were less than 0.30. CONCLUSION IOP is trend to be higher in cold days than warm days. IOP have negative association with both environmental temperature and duration of sunshine. On a season-to-season basis, 24-hour IOP is not highly reproducible in healthy volunteers.
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Affiliation(s)
- Na Liao
- The Eye Hospital, School of Optometry and Ophthalmology, Wenzhou Medical University, Wenzhou 325027, Zhejiang Province, China
| | - Yan-Qian Xie
- The Eye Hospital, School of Optometry and Ophthalmology, Wenzhou Medical University, Wenzhou 325027, Zhejiang Province, China
| | - Guang-Yun Mao
- The Eye Hospital, School of Optometry and Ophthalmology, Wenzhou Medical University, Wenzhou 325027, Zhejiang Province, China
| | - Fan-Jun Bao
- The Eye Hospital, School of Optometry and Ophthalmology, Wenzhou Medical University, Wenzhou 325027, Zhejiang Province, China
| | - Zhong Lin
- The Eye Hospital, School of Optometry and Ophthalmology, Wenzhou Medical University, Wenzhou 325027, Zhejiang Province, China
| | - Hui-Lyu Jiang
- The Eye Hospital, School of Optometry and Ophthalmology, Wenzhou Medical University, Wenzhou 325027, Zhejiang Province, China
| | - Yuan-Bo Liang
- The Eye Hospital, School of Optometry and Ophthalmology, Wenzhou Medical University, Wenzhou 325027, Zhejiang Province, China.,Glaucoma Institute, Wenzhou Medical University, Wenzhou 325027, Zhejiang Province, China
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16
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Soundararajan A, Ghag SA, Vuda SS, Wang T, Pattabiraman PP. Cathepsin K Regulates Intraocular Pressure by Modulating Extracellular Matrix Remodeling and Actin-Bundling in the Trabecular Meshwork Outflow Pathway. Cells 2021; 10:cells10112864. [PMID: 34831087 PMCID: PMC8616380 DOI: 10.3390/cells10112864] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 10/18/2021] [Accepted: 10/21/2021] [Indexed: 02/02/2023] Open
Abstract
The homeostasis of extracellular matrix (ECM) and actin dynamics in the trabecular meshwork (TM) outflow pathway plays a critical role in intraocular pressure (IOP) regulation. We studied the role of cathepsin K (CTSK), a lysosomal cysteine protease and a potent collagenase, on ECM modulation and actin cytoskeleton rearrangements in the TM outflow pathway and the regulation of IOP. Initially, we found that CTSK was negatively regulated by pathological stressors known to elevate IOP. Further, inactivating CTSK using balicatib, a pharmacological cell-permeable inhibitor of CTSK, resulted in IOP elevation due to increased levels and excessive deposition of ECM-like collagen-1A in the TM outflow pathway. The loss of CTSK activity resulted in actin-bundling via fascin and vinculin reorganization and by inhibiting actin depolymerization via phospho-cofilin. Contrarily, constitutive expression of CTSK decreased ECM and increased actin depolymerization by decreasing phospho-cofilin, negatively regulated the availability of active TGFβ2, and reduced the levels of alpha-smooth muscle actin (αSMA), indicating an antifibrotic action of CTSK. In conclusion, these observations, for the first time, demonstrate the significance of CTSK in IOP regulation by maintaining the ECM homeostasis and actin cytoskeleton-mediated contractile properties of the TM outflow pathway.
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Affiliation(s)
- Avinash Soundararajan
- Glick Eye Institute, Department of Ophthalmology, Indiana University School of Medicine, 1160 West Michigan Street, Indianapolis, IN 46202-5209, USA; (A.S.); (S.A.G.); (S.S.V.); (T.W.)
| | - Sachin Anil Ghag
- Glick Eye Institute, Department of Ophthalmology, Indiana University School of Medicine, 1160 West Michigan Street, Indianapolis, IN 46202-5209, USA; (A.S.); (S.A.G.); (S.S.V.); (T.W.)
| | - Sai Supriya Vuda
- Glick Eye Institute, Department of Ophthalmology, Indiana University School of Medicine, 1160 West Michigan Street, Indianapolis, IN 46202-5209, USA; (A.S.); (S.A.G.); (S.S.V.); (T.W.)
| | - Ting Wang
- Glick Eye Institute, Department of Ophthalmology, Indiana University School of Medicine, 1160 West Michigan Street, Indianapolis, IN 46202-5209, USA; (A.S.); (S.A.G.); (S.S.V.); (T.W.)
- Stark Neuroscience Research Institute, 320 West 15th Street, Indianapolis, IN 46202-2266, USA
| | - Padmanabhan Paranji Pattabiraman
- Glick Eye Institute, Department of Ophthalmology, Indiana University School of Medicine, 1160 West Michigan Street, Indianapolis, IN 46202-5209, USA; (A.S.); (S.A.G.); (S.S.V.); (T.W.)
- Stark Neuroscience Research Institute, 320 West 15th Street, Indianapolis, IN 46202-2266, USA
- Correspondence: ; Tel.: +1-317-274-2652
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17
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Identification of Estrogen Signaling in a Prioritization Study of Intraocular Pressure-Associated Genes. Int J Mol Sci 2021; 22:ijms221910288. [PMID: 34638643 PMCID: PMC8508848 DOI: 10.3390/ijms221910288] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 09/20/2021] [Accepted: 09/22/2021] [Indexed: 12/12/2022] Open
Abstract
Elevated intraocular pressure (IOP) is the only modifiable risk factor for primary open-angle glaucoma (POAG). Herein we sought to prioritize a set of previously identified IOP-associated genes using novel and previously published datasets. We identified several genes for future study, including several involved in cytoskeletal/extracellular matrix reorganization, cell adhesion, angiogenesis, and TGF-β signaling. Our differential correlation analysis of IOP-associated genes identified 295 pairs of 201 genes with differential correlation. Pathway analysis identified β-estradiol as the top upstream regulator of these genes with ESR1 mediating 25 interactions. Several genes (i.e., EFEMP1, FOXC1, and SPTBN1) regulated by β-estradiol/ESR1 were highly expressed in non-glaucomatous human trabecular meshwork (TM) or Schlemm’s canal (SC) cells and specifically expressed in TM/SC cell clusters defined by single-cell RNA-sequencing. We confirmed ESR1 gene and protein expression in human TM cells and TM/SC tissue with quantitative real-time PCR and immunofluorescence, respectively. 17β-estradiol was identified in bovine, porcine, and human aqueous humor (AH) using ELISA. In conclusion, we have identified estrogen receptor signaling as a key modulator of several IOP-associated genes. The expression of ESR1 and these IOP-associated genes in TM/SC tissue and the presence of 17β-estradiol in AH supports a role for estrogen signaling in IOP regulation.
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18
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Lieberman RL, Ma MT. Molecular Insights into Myocilin and Its Glaucoma-Causing Misfolded Olfactomedin Domain Variants. Acc Chem Res 2021; 54:2205-2215. [PMID: 33847483 DOI: 10.1021/acs.accounts.1c00060] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Numerous human disorders arise due to the inability of a particular protein to adopt its correct three-dimensional structure in the context of the cell, leading to aggregation. A new addition to the list of such protein conformational disorders is the inherited subtype of glaucoma. Different and rare coding mutations in myocilin, found in families throughout the world, are causal for early onset ocular hypertension, a key glaucoma risk factor. Myocilin is expressed at high levels in the trabecular meshwork (TM) extracellular matrix. The TM is the anatomical region of the eye that regulates intraocular pressure, and its dysfunction is associated with most forms of glaucoma. Disease variants, distributed across the 30 kDa olfactomedin domain (mOLF), cause myocilin to be sequestered intracellularly instead of being secreted to the TM extracellular matrix. The working hypothesis is that the intracellular aggregates cause a toxic gain of function: TM cell death is thought to lead to TM matrix dysfunction, hastening elevated intraocular pressure and subsequent vision loss.Our lab has provided molecular underpinnings for myocilin structure and misfolding, placing myocilin-associated glaucoma within the context of amyloid diseases like Alzheimer and diabetes. We have dissected complexities of the modular wild-type (WT) myocilin structure and associated misfolded states. Our data support the model that full-length WT myocilin adopts a Y-shaped dimer-of-dimers conferred by two different coiled-coil regions, generating new hypotheses regarding its mysterious function. The mOLF β-propellers are paired at each tip of the Y. Disease-associated variants aggregate because mOLFs are less stable, leading to facile aggregation under physiological conditions (37 °C, pH 7.2). Mutant myocilin aggregates exhibit numerous characteristics of amyloid in vitro and in cells, and aggregation proceeds from a partially folded state accessed preferentially by disease variants at physiological conditions. Interestingly, destabilization is not a universal consequence of mutation. We identified counterintuitive, stabilizing point variants that adopt a non-native structure and do not aggregate; however, these variants have not been identified in glaucoma patients. An ongoing effort is predicting the consequence of any given mutation. This effort is relevant to interpreting data from large-scale sequencing projects where clinical and family history data are not available. Finally, our work suggests avenues to develop disease-modifying precision medicines for myocilin-associated glaucoma.
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Affiliation(s)
- Raquel L. Lieberman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Dr. NW, Atlanta, Georgia 30332-0400, United States
| | - Minh Thu Ma
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Dr. NW, Atlanta, Georgia 30332-0400, United States
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19
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Li H, Bagué T, Kirschner A, Strat AN, Roberts H, Weisenthal RW, Patteson AE, Annabi N, Stamer WD, Ganapathy PS, Herberg S. A tissue-engineered human trabecular meshwork hydrogel for advanced glaucoma disease modeling. Exp Eye Res 2021; 205:108472. [PMID: 33516765 PMCID: PMC11097970 DOI: 10.1016/j.exer.2021.108472] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 01/15/2021] [Accepted: 01/20/2021] [Indexed: 12/21/2022]
Abstract
Abnormal human trabecular meshwork (HTM) cell function and extracellular matrix (ECM) remodeling contribute to HTM stiffening in primary open-angle glaucoma (POAG). Most current cellular HTM model systems do not sufficiently replicate the complex native three dimensional (3D) cell-ECM interface, limiting their use for investigating POAG pathology. Tissue-engineered hydrogels are ideally positioned to overcome shortcomings of current models. Here, we report a novel biomimetic HTM hydrogel and test its utility as a POAG disease model. HTM hydrogels were engineered by mixing normal donor-derived HTM cells with collagen type I, elastin-like polypeptide and hyaluronic acid, each containing photoactive functional groups, followed by UV crosslinking. Glaucomatous conditions were induced with dexamethasone (DEX), and effects of the Rho-associated kinase (ROCK) inhibitor Y27632 on cytoskeletal organization and tissue-level function, contingent on HTM cell-ECM interactions, were assessed. DEX exposure increased HTM hydrogel contractility, f-actin and alpha smooth muscle actin abundance and rearrangement, ECM remodeling, and fibronectin deposition - all contributing to HTM hydrogel condensation and stiffening consistent with glaucomatous HTM tissue behavior. Y27632 treatment produced precisely the opposite effects and attenuated the DEX-induced pathologic changes, resulting in HTM hydrogel relaxation and softening. For model validation, confirmed glaucomatous HTM (GTM) cells were encapsulated; GTM hydrogels showed increased contractility, fibronectin deposition, and stiffening vs. normal HTM hydrogels despite reduced GTM cell proliferation. We have developed a biomimetic HTM hydrogel model for detailed investigation of 3D cell-ECM interactions under normal and simulated glaucomatous conditions. Its bidirectional responsiveness to pharmacological challenge and rescue suggests promising potential to serve as screening platform for new POAG treatments with focus on HTM biomechanics.
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Affiliation(s)
- Haiyan Li
- Department of Ophthalmology and 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
| | - Tyler Bagué
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Alexander Kirschner
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Ana N Strat
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Haven Roberts
- Duke Eye Center, Duke University, Durham, NC, 27708, USA
| | - Robert W Weisenthal
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Alison E Patteson
- BioInspired Institute, Syracuse University, Syracuse, NY, 13244, USA; Department of Physics, Syracuse University, Syracuse, NY, 13244, USA
| | - Nasim Annabi
- Department of Chemical and Biomolecular Engineering, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | | | - Preethi S Ganapathy
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, 13210, USA; BioInspired Institute, Syracuse University, Syracuse, NY, 13244, USA; Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Samuel Herberg
- Department of Ophthalmology and 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.
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20
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Lakk M, Križaj D. TRPV4-Rho signaling drives cytoskeletal and focal adhesion remodeling in trabecular meshwork cells. Am J Physiol Cell Physiol 2021; 320:C1013-C1030. [PMID: 33788628 PMCID: PMC8285634 DOI: 10.1152/ajpcell.00599.2020] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Intraocular pressure (IOP) is dynamically regulated by the trabecular meshwork (TM), a mechanosensitive tissue that protects the eye from injury through dynamic regulation of aqueous humor flow. TM compensates for mechanical stress impelled by chronic IOP elevations through increased actin polymerization, tissue stiffness, and contractility. This process has been associated with open angle glaucoma; however, the mechanisms that link mechanical stress to pathological cytoskeletal remodeling downstream from the mechanotransducers remain poorly understood. We used fluorescence imaging and biochemical analyses to investigate cytoskeletal and focal adhesion remodeling in human TM cells stimulated with physiological strains. Mechanical stretch promoted F-actin polymerization, increased the number and size of focal adhesions, and stimulated the activation of the Rho-associated protein kinase (ROCK). Stretch-induced activation of the small GTPase Ras homolog family member A (RhoA), and tyrosine phosphorylations of focal adhesion proteins paxillin, focal adhesion kinase (FAK), vinculin, and zyxin were time dependently inhibited by ROCK inhibitor trans-4-[(1R)-1-aminoethyl]-N-4-pyridinylcyclohexanecarboxamide dihydrochloride (Y-27632), and by HC-067047, an antagonist of transient receptor potential vanilloid 4 (TRPV4) channels. Both TRPV4 and ROCK activation were required for zyxin translocation and increase in the number/size of focal adhesions in stretched cells. Y-27632 blocked actin polymerization without affecting calcium influx induced by membrane stretch and the TRPV4 agonist GSK1016790A. These results reveal that mechanical tuning of TM cells requires parallel activation of TRPV4, integrins, and ROCK, with chronic stress leading to sustained remodeling of the cytoskeleton and focal complexes.
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Affiliation(s)
- Monika Lakk
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, Utah
| | - David Križaj
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, Utah.,Department of Bioengineering, University of Utah, Salt Lake City, Utah.,Department of Neurobiology, University of Utah, Salt Lake City, Utah
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21
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Tabak S, Schreiber-Avissar S, Beit-Yannai E. Crosstalk between MicroRNA and Oxidative Stress in Primary Open-Angle Glaucoma. Int J Mol Sci 2021; 22:2421. [PMID: 33670885 PMCID: PMC7957693 DOI: 10.3390/ijms22052421] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/23/2021] [Accepted: 02/24/2021] [Indexed: 12/13/2022] Open
Abstract
Reactive oxygen species (ROS) plays a key role in the pathogenesis of primary open-angle glaucoma (POAG), a chronic neurodegenerative disease that damages the trabecular meshwork (TM) cells, inducing apoptosis of the retinal ganglion cells (RGC), deteriorating the optic nerve head, and leading to blindness. Aqueous humor (AH) outflow resistance and intraocular pressure (IOP) elevation contribute to disease progression. Nevertheless, despite the existence of pharmacological and surgical treatments, there is room for the development of additional treatment approaches. The following review is aimed at investigating the role of different microRNAs (miRNAs) in the expression of genes and proteins involved in the regulation of inflammatory and degenerative processes, focusing on the delicate balance of synthesis and deposition of extracellular matrix (ECM) regulated by chronic oxidative stress in POAG related tissues. The neutralizing activity of a couple of miRNAs was described, suggesting effective downregulation of pro-inflammatory and pro-fibrotic signaling pathways, including nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB), transforming growth factor-beta 2 (TGF-β2), Wnt/β-Catenin, and PI3K/AKT. In addition, with regards to the elevated IOP in many POAG patients due to increased outflow resistance, Collagen type I degradation was stimulated by some miRNAs and prevented ECM deposition in TM cells. Mitochondrial dysfunction as a consequence of oxidative stress was suppressed following exposure to different miRNAs. In contrast, increased oxidative damage by inhibiting the mTOR signaling pathway was described as part of the action of selected miRNAs. Summarizing, specific miRNAs may be promising therapeutic targets for lowering or preventing oxidative stress injury in POAG patients.
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Affiliation(s)
| | | | - Elie Beit-Yannai
- Department of Clinical Biochemistry and Pharmacology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel; (S.T.); (S.S.-A.)
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22
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Zhu W, Hou F, Fang J, Bahrani Fard MR, Liu Y, Ren S, Wu S, Qi Y, Sui S, Read AT, Sherwood JM, Zou W, Yu H, Zhang J, Overby DR, Wang N, Ethier CR, Wang K. The role of Piezo1 in conventional aqueous humor outflow dynamics. iScience 2021; 24:102042. [PMID: 33532718 PMCID: PMC7829208 DOI: 10.1016/j.isci.2021.102042] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 12/16/2020] [Accepted: 01/05/2021] [Indexed: 12/16/2022] Open
Abstract
Controlling intraocular pressure (IOP) remains the mainstay of glaucoma therapy. The trabecular meshwork (TM), the key tissue responsible for aqueous humor (AH) outflow and IOP maintenance, is very sensitive to mechanical forces. However, it is not understood whether Piezo channels, very sensitive mechanosensors, functionally influence AH outflow. Here, we characterize the role of Piezo1 in conventional AH outflow. Immunostaining and western blot analysis showed that Piezo1 is widely expressed by TM. Patch-clamp recordings in TM cells confirmed the activation of Piezo1-derived mechanosensitive currents. Importantly, the antagonist GsMTx4 for mechanosensitive channels significantly decreased steady-state facility, yet activation of Piezo1 by the specific agonist Yoda1 did not lead to a facility change. Furthermore, GsMTx4, but not Yoda1, caused a significant increase in ocular compliance, a measure of the eye's transient response to IOP perturbation. Our findings demonstrate a potential role for Piezo1 in conventional outflow, likely under pathological and rapid transient conditions. Piezo1 is functionally expressed in the TM, the most important tissue controlling IOP Suppression of mechanosensitive channel leads to a significant decrease in facility Our data suggest a role for Piezo in pathological situations and rapid IOP transients
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Affiliation(s)
- Wei Zhu
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China.,Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beihang University & Capital Medical University, Beijing 100730, China
| | - Fei Hou
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China.,Department of Pharmacy, Affiliated Hospital of Qingdao University, Qingdao 266003, China
| | - Jingwang Fang
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China
| | - Mohammad Reza Bahrani Fard
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta 30332, GA, USA
| | - Yani Liu
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China
| | - Shouyan Ren
- Department of Pharmacy, Affiliated Hospital of Qingdao University, Qingdao 266003, China
| | - Shen Wu
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Beijing 100730 China
| | - Yunkun Qi
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China
| | - Shangru Sui
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China
| | - A Thomas Read
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta 30332, GA, USA
| | | | - Wei Zou
- School of Mechatronic Engineering, Jiangsu Normal University, Xuzhou 221116, China
| | - Hongxia Yu
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China
| | - Jingxue Zhang
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Beijing 100730 China
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, UK
| | - Ningli Wang
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Beijing 100730 China
| | - C Ross Ethier
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta 30332, GA, USA.,Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, 30332, GA, United States
| | - KeWei Wang
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China.,Institute of Innovative Drugs, Qingdao University, 38 Dengzhou Road, Qingdao 266021, Shandong, China
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23
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SB772077B (SB77) Alleviated the Aqueous Outflow Resistance Mediated by Cyclic Mechanical Stress in Perfused Human Cadaveric Eyes. Sci Rep 2020; 10:10202. [PMID: 32576873 PMCID: PMC7311383 DOI: 10.1038/s41598-020-67087-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 06/03/2020] [Indexed: 01/08/2023] Open
Abstract
The intraocular pressure lowering property of a new rho kinase inhibitor, SB772077B (SB77) has been previously demonstrated in perfused human cadaveric eyes. In this study, the efficacy of SB77 in alleviating the aqueous outflow resistance mediated by cyclic mechanical stress in perfused human cadaveric eyes was investigated. A human anterior segment perfusion culture model was used to investigate the effect of cyclic intraocular pressure (IOP) on aqueous outflow facility in presence or absence of SB77. The status of RhoA activation and the downstream effector molecule myosin-light chain phosphorylation (p-MLC) was investigated by Western blot. Cyclic mechanical stress resulted in decrease in aqueous outflow facility (-19.79 ± 4.93%; p = 0.019) in perfused human eyes and treatment with SB77 (50 µM) significantly enhanced outflow facility by 15% (p = 0.05). The increase in outflow facility by SB77 was confirmed with the inactivation of RhoA/ROCK signaling and decreased expression of extracellular matrix markers. SB77 effectively reduced the outflow resistance mediated by cyclic IOP and thus may be a potential clinical candidate for the management of glaucoma.
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24
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Prosseda PP, Alvarado JA, Wang B, Kowal TJ, Ning K, Stamer WD, Hu Y, Sun Y. Optogenetic stimulation of phosphoinositides reveals a critical role of primary cilia in eye pressure regulation. SCIENCE ADVANCES 2020; 6:eaay8699. [PMID: 32494665 PMCID: PMC7190330 DOI: 10.1126/sciadv.aay8699] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 02/11/2020] [Indexed: 05/10/2023]
Abstract
Glaucoma is a group of progressive optic neuropathies that cause irreversible vision loss. Although elevated intraocular pressure (IOP) is associated with the development and progression of glaucoma, the mechanisms for its regulation are not well understood. Here, we have designed CIBN/CRY2-based optogenetic constructs to study phosphoinositide regulation within distinct subcellular compartments. We show that stimulation of CRY2-OCRL, an inositol 5-phosphatase, increases aqueous humor outflow and lowers IOP in vivo, which is caused by a calcium-dependent actin rearrangement of the trabecular meshwork cells. Phosphoinositide stimulation also rescues defective aqueous outflow and IOP in a Lowe syndrome mouse model but not in IFT88fl/fl mice that lack functional cilia. Thus, our study is the first to use optogenetics to regulate eye pressure and demonstrate that tight regulation of phosphoinositides is critical for aqueous humor homeostasis in both normal and diseased eyes.
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Affiliation(s)
- Philipp P. Prosseda
- Department of Ophthalmology, Stanford University School of Medicine, 1651 Page Mill Road, Rm 2220, Palo Alto, CA 94305, USA
| | - Jorge A. Alvarado
- Department of Ophthalmology, Stanford University School of Medicine, 1651 Page Mill Road, Rm 2220, Palo Alto, CA 94305, USA
| | - Biao Wang
- Department of Ophthalmology, Stanford University School of Medicine, 1651 Page Mill Road, Rm 2220, Palo Alto, CA 94305, USA
| | - Tia J. Kowal
- Department of Ophthalmology, Stanford University School of Medicine, 1651 Page Mill Road, Rm 2220, Palo Alto, CA 94305, USA
| | - Ke Ning
- Department of Ophthalmology, Stanford University School of Medicine, 1651 Page Mill Road, Rm 2220, Palo Alto, CA 94305, USA
| | - W. Daniel Stamer
- Duke Eye Center, Department of Ophthalmology, Duke University, Durham, NC 27710, USA
| | - Yang Hu
- Department of Ophthalmology, Stanford University School of Medicine, 1651 Page Mill Road, Rm 2220, Palo Alto, CA 94305, USA
| | - Yang Sun
- Department of Ophthalmology, Stanford University School of Medicine, 1651 Page Mill Road, Rm 2220, Palo Alto, CA 94305, USA
- Palo Alto Veterans Administration, Palo Alto, CA 94304, USA
- Corresponding author.
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25
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Tie J, Chen D, Guo J, Liao S, Luo X, Zhang Y, Guo R, Xu C, Huang D, Zhang Y, Wang J. Transcriptome-wide study of the response of human trabecular meshwork cells to the substrate stiffness increase. J Cell Biochem 2020; 121:3112-3123. [PMID: 32115746 DOI: 10.1002/jcb.29578] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Accepted: 12/09/2019] [Indexed: 02/06/2023]
Abstract
Elevated intraocular pressure, a major risk factor of glaucoma, is caused by the abnormal function of trabecular outflow pathways. Human trabecular meshwork (HTM) tissue plays an important role in the outflow pathways. However, the molecular mechanisms that how TM cells respond to the elevated IOP are largely unknown. We cultured primary HTM cells on polyacrylamide gels with tunable stiffness corresponding to Young's moduli ranging from 1.1 to 50 kPa. Then next-generation RNA sequencing (RNA-seq) was performed to obtain the transcriptomic profiles of HTM cells. Bioinformatics analysis revealed that genes related to glaucoma including DCN, SPARC, and CTGF, were significantly increased with elevated substrate stiffness, as well as the global alteration of HTM transcriptome. Extracellular matrix (ECM)-related genes were selectively activated in response to the elevated substrate stiffness, consistent with the known molecular alteration in glaucoma. Human normal and glaucomatous TM tissues were also obtained to perform RNA-seq experiments and supported the substrate stiffness-altered transcriptome profiles from the in vitro cell model. The current study profiled the transcriptomic changes in human TM cells upon increasing substrate stiffness. Global change of ECM-related genes indicates that the in vitro substrate stiffness could greatly affect the biological processes of HTM cells. The in vitro HTM cell model could efficiently capture the main pathogenetic process in glaucoma patients, and provide a powerful method to investigate the underlying molecular mechanisms.
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Affiliation(s)
- Jinjun Tie
- Tianjin Medical University Eye Institute, Tianjin Medical University, Tianjin, China.,College of Optometry and Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Dong Chen
- Center for Genome Analysis, ABLife Inc., Wuhan, Hubei, China.,Laboratory for Genome Regulation and Human Health, ABLife Inc., Wuhan, Hubei, China
| | - Junhong Guo
- Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Institute, Shenzhen Eye Hospital, Jinan University, Shenzhen, Guangdong, China.,School of Ophthalmology & Optometry, Shenzhen University, Shenzhen, Guangdong, China
| | - Shengjie Liao
- Center for Genome Analysis, ABLife Inc., Wuhan, Hubei, China.,Laboratory for Genome Regulation and Human Health, ABLife Inc., Wuhan, Hubei, China
| | - Xiaotian Luo
- Laboratory for Genome Regulation and Human Health, ABLife Inc., Wuhan, Hubei, China
| | - Yu Zhang
- Center for Genome Analysis, ABLife Inc., Wuhan, Hubei, China
| | - Ruru Guo
- Tianjin Medical University Eye Institute, Tianjin Medical University, Tianjin, China
| | - Chenjia Xu
- Tianjin Medical University Eye Institute, Tianjin Medical University, Tianjin, China.,College of Optometry and Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Dandan Huang
- Tianjin Medical University Eye Institute, Tianjin Medical University, Tianjin, China.,College of Optometry and Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Yi Zhang
- Center for Genome Analysis, ABLife Inc., Wuhan, Hubei, China.,Laboratory for Genome Regulation and Human Health, ABLife Inc., Wuhan, Hubei, China
| | - Jiantao Wang
- Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Institute, Shenzhen Eye Hospital, Jinan University, Shenzhen, Guangdong, China.,School of Ophthalmology & Optometry, Shenzhen University, Shenzhen, Guangdong, China
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26
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How many aqueous humor outflow pathways are there? Surv Ophthalmol 2019; 65:144-170. [PMID: 31622628 DOI: 10.1016/j.survophthal.2019.10.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 09/29/2019] [Accepted: 10/04/2019] [Indexed: 12/31/2022]
Abstract
The aqueous humor (AH) outflow pathways definition is still matter of intense debate. To date, the differentiation between conventional (trabecular meshwork) and unconventional (uveoscleral) pathways is widely accepted, distinguishing the different impact of the intraocular pressure on the AH outflow rate. Although the conventional route is recognized to host the main sites for intraocular pressure regulation, the unconventional pathway, with its great potential for AH resorption, seems to act as a sort of relief valve, especially when the trabecular resistance rises. Recent evidence demonstrates the presence of lymphatic channels in the eye and proposes that they may participate in the overall AH drainage and intraocular pressure regulation, in a presumably adaptive fashion. For this reason, the uveolymphatic route is increasingly thought to play an important role in the ocular hydrodynamic system physiology. As a result of the unconventional pathway characteristics, hydrodynamic disorders do not develop until the adaptive routes cannot successfully counterbalance the increased AH outflow resistance. When their adaptive mechanisms fail, glaucoma occurs. Our review deals with the standard and newly discovered AH outflow routes, with particular attention to the importance they may have in opening new therapeutic strategies in the treatment of ocular hypertension and glaucoma.
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27
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Siegfried CJ, Shui YB. Intraocular Oxygen and Antioxidant Status: New Insights on the Effect of Vitrectomy and Glaucoma Pathogenesis. Am J Ophthalmol 2019; 203:12-25. [PMID: 30772349 DOI: 10.1016/j.ajo.2019.02.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 02/03/2019] [Accepted: 02/06/2019] [Indexed: 12/26/2022]
Abstract
PURPOSE The purpose of this study was to investigate correlations of partial pressure of oxygen (pO2) in the ocular anterior segment of human eyes and aqueous humor antioxidant levels of ascorbate (AsA) and total reactive antioxidant potential (TRAP) with glaucoma and vitreous status. METHODS This prospective, cross-sectional study stratified patients (n = 288 eyes) by lens and vitreous status and the presence of primary open-angle glaucoma for statistical analyses. Intraocular pO2 concentrations were measured using a fiberoptic probe in patients at the beginning of planned glaucoma and/or cataract surgery. Aqueous humor specimens were obtained for antioxidant analysis of AsA and TRAP. RESULTS Following prior pars plana vitrectomy, pO2 levels were significantly higher than in the reference group of cataract surgery in the anterior chamber angle (16.2 ± 5.0 vs. 13.0 ± 3.9 mm Hg; P = .0171) and in the posterior chamber (7.6 ± 3.1 vs. 3.9 ± 2.7 mm Hg; P < .0001). AsA and TRAP levels were significantly lower (1.1 ± 0.4 vs. 1.4 ± 0.5 mM, respectively; 403.3 ±116.5 vs. 479.0 ± 146.7 Trolox units, respectively; P = .004 and P = .024, respectively) in patients after vitrectomy. In patients with an intact vitreous, neither pO2 nor antioxidant status correlated with lens status or glaucoma. CONCLUSIONS Increased pO2 and antioxidant depletion following vitrectomy suggests an alteration of the intraocular oxidant-antioxidant balance. Our study links physiologic factors such as increased pO2 in the anterior chamber angle and the posterior chamber to decreased antioxidant levels in aqueous humor following vitrectomy. Oxidative stress/damage to the trabecular meshwork in such post-vitrectomy cases may contribute to intraocular pressure elevation and increased risk of glaucoma. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.
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Affiliation(s)
- Carla J Siegfried
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri.
| | - Ying-Bo Shui
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri
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28
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Ren R, Li G, Le TD, Kopczynski C, Stamer WD, Gong H. Netarsudil Increases Outflow Facility in Human Eyes Through Multiple Mechanisms. Invest Ophthalmol Vis Sci 2017; 57:6197-6209. [PMID: 27842161 PMCID: PMC5114035 DOI: 10.1167/iovs.16-20189] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Purpose Netarsudil is a Rho kinase/norepinephrine transporter inhibitor currently in phase 3 clinical development for glaucoma treatment. We investigated the effects of its active metabolite, netarsudil-M1, on outflow facility (C), outflow hydrodynamics, and morphology of the conventional outflow pathway in enucleated human eyes. Methods Paired human eyes (n = 5) were perfused with either 0.3 μM netarsudil-M1 or vehicle solution at constant pressure (15 mm Hg). After 3 hours, fluorescent microspheres were added to perfusion media to trace the outflow patterns before perfusion-fixation. The percentage effective filtration length (PEFL) was calculated from the measured lengths of tracer distribution in the trabecular meshwork (TM), episcleral veins (ESVs), and along the inner wall (IW) of Schlemm's canal after global and confocal imaging. Morphologic changes along the trabecular outflow pathway were investigated by confocal, light, and electron microscopy. Results Perfusion with netarsudil-M1 significantly increased C when compared to baseline (51%, P < 0.01) and to paired controls (102%, P < 0.01), as well as significantly increased PEFL in both IW (P < 0.05) and ESVs (P < 0.01). In treated eyes, PEFL was significantly higher in ESVs than in the IW (P < 0.01) and was associated with increased cross-sectional area of ESVs (P < 0.01). Percentage effective filtration length in ESVs positively correlated with the percentage change in C (R2 = 0.58, P = 0.01). A significant increase in juxtacanalicular connective tissue (JCT) thickness (P < 0.05) was found in treated eyes compared to controls. Conclusions Netarsudil acutely increased C by expansion of the JCT and dilating the ESVs, which led to redistribution of aqueous outflow through a larger area of the IW and ESVs.
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Affiliation(s)
- Ruiyi Ren
- Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States 2Department of Anatomoy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Guorong Li
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Thuy Duong Le
- Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Casey Kopczynski
- Aerie Pharmaceuticals, Inc., Durham, North Carolina, United States
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Haiyan Gong
- Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States 2Department of Anatomoy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts, United States
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29
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Hirt J, Liton PB. Autophagy and mechanotransduction in outflow pathway cells. Exp Eye Res 2017; 158:146-153. [PMID: 27373974 PMCID: PMC5199638 DOI: 10.1016/j.exer.2016.06.021] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 06/23/2016] [Accepted: 06/27/2016] [Indexed: 12/19/2022]
Abstract
Because of elevations in IOP and other forces, cells in the trabecular meshwork (TM) are constantly subjected to mechanical strain. In order to preserve cellular function and regain homeostasis, cells must sense and adapt to these morphological changes. We and others have already shown that mechanical stress can trigger a broad range of responses in TM cells; however, very little is known about the strategies that TM cells use to respond to this stress, so they can adapt and survive. Autophagy, a lysosomal degradation pathway, has emerged as an important cellular homeostatic mechanism promoting cell survival and adaptation to a number of cytotoxic stresses. Our laboratory has reported the activation of autophagy in TM cells in response to static biaxial strain and high pressure. Moreover, our newest data also suggest the activation of chaperon-assisted selective autophagy, a recently identified tension-induced autophagy essential for mechanotransduction, in TM cells under cyclic mechanical stress. In this review manuscript we will discuss autophagy as part of an integrated response triggered in TM cells in response to strain, exerting a dual role in repair and mechanotransduction, and the potential effects of dysregulated in outflow pathway pathophysiology.
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Affiliation(s)
- Joshua Hirt
- Duke University, Department of Ophthalmology, Durham, NC, USA
| | - Paloma B Liton
- Duke University, Department of Ophthalmology, Durham, NC, USA.
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30
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Xin C, Wang RK, Song S, Shen T, Wen J, Martin E, Jiang Y, Padilla S, Johnstone M. Aqueous outflow regulation: Optical coherence tomography implicates pressure-dependent tissue motion. Exp Eye Res 2017; 158:171-186. [PMID: 27302601 PMCID: PMC5272871 DOI: 10.1016/j.exer.2016.06.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 05/21/2016] [Accepted: 06/09/2016] [Indexed: 12/28/2022]
Abstract
Glaucoma is a leading cause of blindness worldwide and results from damage to the optic nerve. Currently, intraocular pressure is the only treatable risk factor. Changes in aqueous outflow regulate pressure; regulation becomes abnormal in glaucoma. From inside the eye aqueous flows out through the trabecular meshwork into a venous sinus called Schlemm's canal, next into collector channels and finally returns to the episcleral vessels of the venous system. The location of aqueous outflow regulation is unknown. Ex vivo and in vivo studies implicate both pressure-dependent trabecular tissue motion and tissues distal to Schlemm's canal in regulation of aqueous outflow. Technologies have not previously been available to study these issues. New ex vivo imaging in human eyes identifies hinged flaps or leaflets at collector channel entrances using a high-resolution spectral domain optical coherence tomography (SD-OCT) platform. The hinged flaps open and close in synchrony with pressure-dependent trabecular meshwork motion. The SD-OCT platform images from the trabecular meshwork surface while experimentally changing transtrabecular pressure gradients. New in vivo imaging in human eyes uses a motion sensitive technology, phase-sensitive OCT to quantitate real-time pulse-dependent trabecular tissue motion as well as absence of such motion when aqueous access to the outflow system is blocked. The recent studies suggest that aqueous outflow regulation results from synchronous pressure-dependent motion involving a network of interconnected tissues including those distal to Schlemm's canal. The new imaging technologies may shed light on glaucoma mechanisms and provide guidance in the management of medical, laser and surgical decisions in glaucoma.
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Affiliation(s)
- Chen Xin
- Department of Bioengineering, University of Washington, USA; Department of Ophthalmology, Beijing Anzhen Hospital, Capital Medical University, China.
| | - Ruikang K Wang
- Department of Bioengineering, University of Washington, USA; Department of Ophthalmology, University of Washington, USA.
| | - Shaozhen Song
- Department of Bioengineering, University of Washington, USA.
| | - Tueng Shen
- Department of Bioengineering, University of Washington, USA; Department of Ophthalmology, University of Washington, USA.
| | - Joanne Wen
- Department of Ophthalmology, University of Washington, USA.
| | | | - Yi Jiang
- Department of Ophthalmology, University of Washington, USA.
| | - Steven Padilla
- Department of Ophthalmology, University of Washington, USA.
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Saccà SC, Gandolfi S, Bagnis A, Manni G, Damonte G, Traverso CE, Izzotti A. From DNA damage to functional changes of the trabecular meshwork in aging and glaucoma. Ageing Res Rev 2016; 29:26-41. [PMID: 27242026 DOI: 10.1016/j.arr.2016.05.012] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 05/25/2016] [Accepted: 05/26/2016] [Indexed: 12/24/2022]
Abstract
Glaucoma is a degenerative disease of the eye. Both the anterior and posterior segments of the eye are affected, extensive damage being detectable in the trabecular meshwork and the inner retina-central visual pathway complex. Oxidative stress is claimed to be mainly responsible for molecular damage in the anterior chamber. Indeed, oxidation harms the trabecular meshwork, leading eventually to endothelial cell decay, tissue malfunction, subclinical inflammation, changes in the extracellular matrix and cytoskeleton, altered motility, reduced outflow facility and (ultimately) increased IOP. Moreover, free radicals are involved in aging and can be produced in the brain (as well as in the eye) as a result of ischemia, leading to oxidation of the surrounding neurons. Glaucoma-related cell death occurs by means of apoptosis, and apoptosis is triggered by oxidative stress via (a) mitochondrial damage, (b) inflammation, (c) endothelial dysregulation and dysfunction, and (d) hypoxia. The proteomics of the aqueous humor is significantly altered in glaucoma as a result of oxidation-induced trabecular damage. Those proteins whose aqueous humor levels are increased in glaucoma are biomarkers of trabecular meshwork impairment. Their diffusion from the anterior to the posterior segment of the eye may be relevant in the cascade of events triggering apoptosis in the inner retinal layers, including the ganglion cells.
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Affiliation(s)
- Sergio Claudio Saccà
- IRCCS San Martino University Hospital, Department of Neuroscience and Sense Organs, San Martino Hospital, Ophthalmology Unit, Viale Benedetto XV, 16132 Genoa, Italy.
| | - Stefano Gandolfi
- Ophthalmology Unit, Department of Biological, Biotechnological and Translational Sciences, University of Parma, Parma, Italy
| | - Alessandro Bagnis
- University of Genoa, Eye Clinic, Department of Neuroscience and Sense Organs, Viale Benedetto XV, 5, 16148 Genoa, Italy
| | - Gianluca Manni
- Dept. of Clinical Science and Translational Medicine, University Tor Vergata, Rome, Italy
| | - Gianluca Damonte
- Dept. of Experimental Medicine, Section of Biochemistry and Center of Excellence for Biomedical Research, University of Genoa, Viale Benedetto XV 1, 16132 Genoa, Italy
| | - Carlo Enrico Traverso
- University of Genoa, Eye Clinic, Department of Neuroscience and Sense Organs, Viale Benedetto XV, 5, 16148 Genoa, Italy
| | - Alberto Izzotti
- Mutagenesis Unit, IRCCS San Martino University Hospital, IST National Institute for Cancer Research, Department of Health Sciences, University of Genoa, Via A. Pastore 1, Genoa I-16132, Italy
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Stamer WD, Clark AF. The many faces of the trabecular meshwork cell. Exp Eye Res 2016; 158:112-123. [PMID: 27443500 DOI: 10.1016/j.exer.2016.07.009] [Citation(s) in RCA: 163] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 06/19/2016] [Accepted: 07/16/2016] [Indexed: 12/26/2022]
Abstract
With the combined purpose of facilitating useful vision over a lifetime, a number of ocular cells have evolved specialized features not found elsewhere in the body. The trabecular meshwork (TM) cell at the irido-corneal angle, which is a key regulator of intraocular pressure, is no exception. Examination of cells in culture isolated from the human TM has shown that they are unique in many ways, displaying characteristic features of several different cell types. Thus, these neural crest derived cells display expression patterns and behaviors typical of endothelia, fibroblasts, smooth muscle and macrophages, owing to the multiple roles and two distinct environments where they operate to maintain intraocular pressure homeostasis. In most individuals, TM cells function normally over a lifetime in the face of persistent stressors, including phagocytic, oxidative, mechanical and metabolic stress. Study of TM cells isolated from ocular hypertensive eyes has shown a compromised ability to perform their daily duties. This review highlights the many responsibilities of the TM cell and its challenges, progress in our understanding of TM biology over the past 30 years, as well as discusses unanswered questions about TM dysfunction that results in IOP dysregulation and glaucoma.
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Affiliation(s)
- W Daniel Stamer
- Departments of Ophthalmology and Biomedical Engineering, Duke University, Durham, NC, United States
| | - Abbot F Clark
- North Texas Eye Research Institute, University of North Texas Health Science Center, Ft. Worth, TX, United States.
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Chan MPY, Grossi CM, Khawaja AP, Yip JLY, Khaw KT, Patel PJ, Khaw PT, Morgan JE, Vernon SA, Foster PJ. Associations with Intraocular Pressure in a Large Cohort: Results from the UK Biobank. Ophthalmology 2016; 123:771-82. [PMID: 26795295 PMCID: PMC4819446 DOI: 10.1016/j.ophtha.2015.11.031] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 10/03/2015] [Accepted: 11/15/2015] [Indexed: 10/25/2022] Open
Abstract
PURPOSE To describe the associations of physical and demographic factors with Goldmann-correlated intraocular pressure (IOPg) and corneal-compensated intraocular pressure (IOPcc) in a British cohort. DESIGN Cross-sectional study within the UK Biobank, a large-scale multisite cohort study in the United Kingdom. PARTICIPANTS We included 110 573 participants from the UK Biobank with intraocular pressure (IOP) measurements available. Their mean age was 57 years (range, 40-69 years); 54% were women, and 90% were white. METHODS Participants had 1 IOP measurement made on each eye using the Ocular Response Analyzer noncontact tonometer. Linear regression models were used to assess the associations of IOP with physical and demographic factors. MAIN OUTCOME MEASURES The IOPg and IOPcc. RESULTS The mean IOPg was 15.72 mmHg (95% confidence interval [CI], 15.70-15.74 mmHg), and the mean IOPcc was 15.95 mmHg (15.92-15.97 mmHg). After adjusting for covariates, IOPg and IOPcc were both significantly associated with older age, male sex, higher systolic blood pressure (SBP), faster heart rate, greater myopia, self-reported glaucoma, and colder season (all P < 0.001). The strongest determinants of both IOPg and IOPcc were SBP (partial R(2): IOPg 2.30%, IOPcc 2.26%), followed by refractive error (IOPg 0.60%, IOPcc 1.04%). The following variables had different directions of association with IOPg and IOPcc: height (-0.77 mmHg/m IOPg; 1.03 mmHg/m IOPcc), smoking (0.19 mmHg IOPg, -0.35 mmHg IOPcc), self-reported diabetes (0.41 mmHg IOPg, -0.05 mmHg IOPcc), and black ethnicity (-0.80 mmHg IOPg, 0.77 mmHg IOPcc). This suggests that height, smoking, diabetes, and ethnicity are related to corneal biomechanical properties. The increase in both IOPg and IOPcc with age was greatest among those of mixed ethnicities, followed by blacks and whites. The same set of covariates explained 7.4% of the variability of IOPcc but only 5.3% of the variability of IOPg. CONCLUSIONS This analysis of associations with IOP in a large cohort demonstrated that some variables clearly have different associations with IOPg and IOPcc, and that these 2 measurements may reflect different biological characteristics.
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Affiliation(s)
- Michelle P Y Chan
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, United Kingdom
| | - Carlota M Grossi
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, United Kingdom
| | - Anthony P Khawaja
- Department of Public Health & Primary Care, University of Cambridge, Cambridge, United Kingdom
| | - Jennifer L Y Yip
- Department of Public Health & Primary Care, University of Cambridge, Cambridge, United Kingdom
| | - Kay-Tee Khaw
- Department of Public Health & Primary Care, University of Cambridge, Cambridge, United Kingdom
| | - Praveen J Patel
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, United Kingdom
| | - Peng T Khaw
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, United Kingdom
| | - James E Morgan
- School of Optometry & Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Stephen A Vernon
- Department of Ophthalmology, Nottingham University Hospital NHS Trust, Nottingham, United Kingdom
| | - Paul J Foster
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, United Kingdom.
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Abstract
The connection between Helicobacter pylori (Hp) infection and eye diseases has been increasingly reported in the literature and in active research. The implication of this bacterium in chronic eye diseases, such as blepharitis, glaucoma, central serous chorioretinopathy and others, has been hypothesized. Although the mechanisms by which this association occurs are currently unknown, this review describes shared pathogenetic mechanisms in an attempt to identify a lowest common denominator between eye diseases and Hp infection. The aim of this review is to assess whether different studies could be compared and to establish whether or not Hp infection and Eye diseases share common pathogenetic aspects. In particular, it has been focused on oxidative damage as a possible link between these pathologies. Text word search in Medline from 1998 to July 2014. 152 studies were included in our review. Were taken into considerations only studies that related eye diseases more frequent and/or known. Likely oxidative stress plays a key role. All of the diseases studied seem to follow a common pattern that implicates a cellular response correlated with a sublethal dose of oxidative stress. These alterations seem to be shared by both Hp infections and ocular diseases and include the following: decline in mitochondrial function, increases in the rate of reactive oxygen species production, accumulation of mitochondrial DNA mutations, increases in the levels of oxidative damage to DNA, proteins and lipids, and decreases in the capacity to degrade oxidatively damaged proteins and other macromolecules. This cascade of events appears to repeat itself in different diseases, regardless of the identity of the affected tissue. The trabecular meshwork, conjunctiva, and retina can each show how oxidative stress may acts as a common disease effector as the Helicobacter infection spreads, supported by the increased oxidative damage and other inflammation.
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Affiliation(s)
- Sergio Claudio Saccà
- From the IRCCS Azienda Ospedaliera Universitaria San Martino - IST Department of Head/Neck Pathologies, St Martino Hospital, Ophthalmology Unit, 16132 Genoa, Italy (SCS); Department of Neurosciences, Ophthalmology and Genetics, University of Genoa, Eye Clinic, 16132 Genoa, Italy (AV); Department of Health Sciences, University of Genoa, 16132 Genoa, Italy (AP, AI); Mutagenesis Unit, IRCCS Azienda Ospedaliera Universitaria San Martino - IST, National Institute for Cancer Research, 16132 Genoa, Italy (AI)
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Saccà SC, Pulliero A, Izzotti A. The Dysfunction of the Trabecular Meshwork During Glaucoma Course. J Cell Physiol 2014; 230:510-25. [DOI: 10.1002/jcp.24826] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 09/05/2014] [Indexed: 12/22/2022]
Affiliation(s)
- Sergio Claudio Saccà
- Department of Head/Neck Pathologies; St Martino Hospital; Ophthalmology Unit; Genoa Italy
| | - Alessandra Pulliero
- Department of Health Sciences; Section of Hygiene and Preventive Medicine; University of Genoa; Genoa Italy
| | - Alberto Izzotti
- Department of Health Sciences; Section of Hygiene and Preventive Medicine; University of Genoa; Genoa Italy
- Mutagenesis Unit; IST National Institute for Cancer Research; IRCCS Hospital-University San Martino Company; Genoa Italy
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Johnstone MA. Intraocular pressure regulation: findings of pulse-dependent trabecular meshwork motion lead to unifying concepts of intraocular pressure homeostasis. J Ocul Pharmacol Ther 2014; 30:88-93. [PMID: 24359130 PMCID: PMC3991971 DOI: 10.1089/jop.2013.0224] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 11/21/2013] [Indexed: 11/13/2022] Open
Abstract
Intraocular pressure (IOP) is the only treatable risk factor in glaucoma, one of the world's leading causes of blindness. Mechanisms that maintain IOP within a normal range have been poorly understood in contrast to intrinsic mechanisms that regulate systemic blood pressure. Vessel walls experience continuous pulse-induced cyclic pressure and flow. Pressure-dependent wall stress and flow-dependent shear stress provide sensory signals that initiate mechanotransduction responses. The responses optimize vessel wall elasticity, compliance and lumen size, providing a feedback loop to maintain intrinsic pressure homeostasis. Aqueous humor is part of a vascular circulatory loop, being secreted into the anterior chamber of the eye from the vasculature, then returning to the vasculature by passing through the trabecular meshwork (TM), a uniquely modified vessel wall interposed between the anterior chamber and a vascular sinus called Schlemm's canal (SC). Since pressure in circulatory loops elsewhere is modulated by cyclic stresses, one might predict similar pressure modulation in the aqueous outflow system. Recent laboratory evidence in fact demonstrates that cyclic IOP changes alter aqueous outflow while increasing cellularity and contractility of TM cells. Cyclic changes also lead to alterations in gene expression, changes in cytoskeletal networks and modulation of signal transduction. A new technology, phase-based optical coherence tomography, demonstrates in vivo pulse-dependent TM motion like that elsewhere in the vasculature. Recognition of pulse-dependent TM motion provides a linkage to well-characterized mechanisms that provide pressure homeostasis in the systemic vasculature. The linkage may permit unifying concepts of pressure control and provide new insights into IOP homeostatic mechanisms.
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Affiliation(s)
- Murray A Johnstone
- Department of Ophthalmology, University of Washington , Seattle, Washington
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37
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Acott TS, Kelley MJ, Keller KE, Vranka JA, Abu-Hassan DW, Li X, Aga M, Bradley JM. Intraocular pressure homeostasis: maintaining balance in a high-pressure environment. J Ocul Pharmacol Ther 2014; 30:94-101. [PMID: 24401029 DOI: 10.1089/jop.2013.0185] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Although glaucoma is a relatively common blinding disease, most people do not develop glaucoma. A robust intraocular pressure (IOP) homeostatic mechanism keeps ocular pressures within relatively narrow acceptable bounds throughout most peoples' lives. The trabecular meshwork and/or Schlemm's canal inner wall cells respond to sustained IOP elevation and adjust the aqueous humor outflow resistance to restore IOP to acceptable levels. It appears that the cells sense IOP elevations as mechanical stretch or distortion of the actual outflow resistance and respond by initiating a complex extracellular matrix (ECM) turnover process that takes several days to complete. Although considerable information pertinent to this process is available, many aspects of the IOP homeostatic process remain to be elucidated. Components and mechanisms beyond ECM turnover could also be relevant to IOP homeostasis, but will not be addressed in detail here. Known aspects of the IOP homeostasis process as well as possible ways that it might function and impact glaucoma are discussed.
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Affiliation(s)
- Ted S Acott
- Casey Eye Institute, Oregon Health & Science University , Portland, Oregon
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38
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Gonzalez P, Li G, Qiu J, Wu J, Luna C. Role of microRNAs in the trabecular meshwork. J Ocul Pharmacol Ther 2014; 30:128-37. [PMID: 24383444 DOI: 10.1089/jop.2013.0191] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
MicroRNAs (miRNAs) are now recognized as important post-transcriptional regulators of gene expression. MiRNAs are known to modulate cellular functions relevant to the normal and pathological physiology of the trabecular meshwork (TM) such as cell contraction and extracellular matrix turnover. There is also increasing evidence supporting the role of miRNAs in the pathogenesis of multiple diseases, and their potential value as both biomarkers of disease and therapeutic targets. However, compared with other tissues, our current knowledge regarding the roles played by miRNAs in the TM is still very limited. Here, we review the information currently available about miRNAs in the TM and discuss the main challenges and opportunities to incorporate the rapid progress in miRNA biology to the understanding of the normal and pathological physiology of the TM, and to develop novel clinical applications for diagnosis and therapy of high intraocular pressure.
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Affiliation(s)
- Pedro Gonzalez
- Department of Ophthalmology, Duke University , Durham, North Carolina
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39
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Pokrovskaya O, Wallace D, O’Brien C. The Emerging Role of Statins in Glaucoma Pathological Mechanisms and Therapeutics. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/ojoph.2014.44021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
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40
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Li P, Shen TT, Johnstone M, Wang RK. Pulsatile motion of the trabecular meshwork in healthy human subjects quantified by phase-sensitive optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2013; 4:2051-65. [PMID: 24156063 PMCID: PMC3799665 DOI: 10.1364/boe.4.002051] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 07/29/2013] [Accepted: 07/30/2013] [Indexed: 05/19/2023]
Abstract
Aqueous leaves the anterior chamber of eye by passing through the trabecular meshwork (TM), a tissue thought to be responsible for increased outflow resistance in glaucoma. Motion assessment could permit characterization of TM biomechanical properties necessary to maintain intra-ocular pressure (IOP) within a narrow homeostatic range. In this paper, we report the first in vivo identification of TM motion in humans. We use a phase-sensitive optical coherence tomography (PhS-OCT) system with sub-nanometer sensitivity to detect and image dynamic pulse-induced TM motion. To permit quantification of TM motion and relationships we develop and apply a phase compensation algorithm permitting removal of the otherwise evitable confounding effects of bulk motion. Twenty healthy human eyes from 10 subjects are imaged. The results permit visualization of pulsatile TM motion visualization by PhS-OCT; correlation with the digital/cardiac pulse is highly significant. The correlation permits assessment of the phase lag and time delay between TM motion and the cardiac pulse. In this study, we find that the digital pulse leads the pulsatile TM motion by a mean phase of 3.53 ± 0.48 rad and a mean time of 0.5 ± 0.14 s in the fundamental frequency. A significant linear relationship is present between the TM phase lag and the heart rate (p value < 0.05). The TM phase lag is also affected by age, the relationship not quite reaching significance in the current study. PhS-OCT reveals pulse-induced motion of the TM that may provide insights into the biomechanics of the tissues involved in the regulation of IOP.
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Affiliation(s)
- Peng Li
- Departments of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Tueng T. Shen
- Departments of Bioengineering, University of Washington, Seattle, WA 98195, USA
- Department of Ophthalmology, University of Washington, Seattle, WA 98195, USA
| | - Murray Johnstone
- Department of Ophthalmology, University of Washington, Seattle, WA 98195, USA
| | - Ruikang K. Wang
- Departments of Bioengineering, University of Washington, Seattle, WA 98195, USA
- Department of Ophthalmology, University of Washington, Seattle, WA 98195, USA
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41
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Abstract
PURPOSE OF REVIEW Regulation of intraocular pressure by the conventional (trabecular) outflow pathway is complicated, involving a myriad of mechanical and chemical signals. In most, intraocular pressure is maintained within a tight range over a lifetime. Unfortunately in some, dysfunction results in ocular hypertension and open-angle glaucoma. In the context of established knowledge, this review summarizes recent investigations of conventional outflow function, with the goal of identifying areas for future inquiry and therapeutic targeting. RECENT FINDINGS Mechanical stimulation of conventional outflow cells due to intraocular pressure fluctuations impacts contractility, gene expression, pore formation, enzyme activity, and signaling. Numerous local signaling mediators in the conventional pathway such as bioactive lipids, cytokines, nitric oxide, and nucleotides participate in the regulation of outflow. Interestingly outflow through the conventional pathway is not uniform, but segmental, with passageways constantly changing due to focal protease activity of trabecular cells clearing extracellular matrix materials. The relationship between extracellular matrix expression and trabecular meshwork contractility appears to coordinately impact outflow resistance and is the target of a new class of drugs, the Rho kinase inhibitors. SUMMARY The conventional outflow pathway is a dynamic, pressure-sensitive tissue that is vulnerable to pathology on many fronts, each representing a therapeutic opportunity.
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42
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Li G, Gonzalez P, Camras LJ, Navarro I, Qiu J, Challa P, Stamer WD. Optimizing gene transfer to conventional outflow cells in living mouse eyes. Exp Eye Res 2013; 109:8-16. [PMID: 23337742 DOI: 10.1016/j.exer.2013.01.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 12/22/2012] [Accepted: 01/07/2013] [Indexed: 10/27/2022]
Abstract
The mouse eye has physiological and genetic advantages to study conventional outflow function. However, its small size and shallow anterior chamber presents technical challenges to efficient intracameral delivery of genetic material to conventional outflow cells. The goal of this study was to optimize methods to overcome this technical hurdle, without damaging ocular structures or compromising outflow function. Gene targeting was monitored by immunofluorescence microscopy after transduction of adenovirus encoding green fluorescent protein driven by a CMV promoter. Guided by a micromanipulator and stereomicroscope, virus was delivered intracamerally to anesthetized mice by bolus injection using a 33 gauge needle attached to Hamilton syringe or infusion with glass micropipette connected to syringe pump. The total number of particles introduced remained constant, while volume of injected virus solution (3-10 μl) was varied for each method and time of infusion (3-40 min) tested. Outflow facility and intraocular pressure were monitored invasively using established techniques. Unlike bolus injections or slow infusions, introduction of virus intracamerally during rapid infusions (3 min) at any volume tested preferentially targeted trabecular meshwork and Schlemm's canal cells, with minimal transduction of neighboring cells. While infusions resulted in transient intraocular pressure spikes (commensurate with volume infused, Δ40-70 mmHg), eyes typically recovered within 60 min. Transduced eyes displayed normal outflow facility and tissue morphology 3-6 days after infusions. Taken together, fast infusion of virus solution in small volumes intracamerally is a novel and effective method to selectively deliver agents to conventional outflow cells in living mice.
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Affiliation(s)
- G Li
- Department of Ophthalmology, Duke University School of Medicine, Box 3802, Durham, NC 27710, USA
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43
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Palko JR, Pan X, Liu J. Dynamic testing of regional viscoelastic behavior of canine sclera. Exp Eye Res 2011; 93:825-32. [PMID: 21983041 DOI: 10.1016/j.exer.2011.09.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2011] [Revised: 09/16/2011] [Accepted: 09/27/2011] [Indexed: 11/25/2022]
Abstract
Intraocular pressure (IOP) fluctuations have gained recent clinical interest and thus warrant an understanding of how the sclera responds to dynamic mechanical insults. The objective of this study was to characterize the regional dynamic viscoelastic properties of canine sclera under physiological cyclic loadings. Scleral strips were excised from the anterior, equatorial, and posterior sclera in ten canine eyes. The dimensions of each strip were measured using a high resolution ultrasound imaging system. The strips were tested in a humidity chamber at approximately 37 °C using a Rheometrics Systems Analyzer. A cyclic strain input (0.25%, 1 Hz) was applied to the strips, superimposed upon pre-stresses corresponding to an IOP of 15, 25, and 45 mmHg. The cyclic stress output was recorded and the dynamic properties were calculated based on linear viscoelasticity. Uni-axial tensile tests were also performed on the same samples and the results were compared to those reported for human eyes. The results showed that the sclera's resistance to dynamic loading increased significantly while the damping capability decreased significantly with increasing pre-stresses for all regions of sclera (P < 0.001). Anterior sclera appeared to have a significantly higher damping capability than equatorial and posterior sclera (P = 0.003 and 0.018, respectively). The secant modulus from uni-axial tensile tests showed a decreasing trend from anterior to posterior sclera, displaying a similar pattern as in the human eye. In conclusion, all scleral regions in the canine eyes exhibited an increased ability to resist and a decreased ability to dampen cyclic stress insults at increasing pre-stress (i.e., increasing steady-state IOP). The regional variation of the dynamic properties differed from those of uni-axial tensile tests. Dynamic testing may provide useful information to better understand the mechanical behavior of the sclera in response to dynamic IOP.
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Affiliation(s)
- Joel R Palko
- College of Medicine, The Ohio State University, Ohio, USA
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44
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Luna C, Li G, Qiu J, Epstein DL, Gonzalez P. MicroRNA-24 regulates the processing of latent TGFβ1 during cyclic mechanical stress in human trabecular meshwork cells through direct targeting of FURIN. J Cell Physiol 2011; 226:1407-14. [PMID: 20945401 DOI: 10.1002/jcp.22476] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Cyclic mechanical stress (CMS) leads to alterations of cellular functions in the trabecular meshwork (TM), including the up-regulation of transforming growth factor beta 1 (TGFβ1), that can potentially contribute to the pathogenesis of glaucoma. Although microRNAs (miRNAs) are known to play important roles in many biological functions, little is known about their potential involvement in the cellular responses elicited by mechanical stress. Here we analyzed changes in miRNA expression induced by CMS, and examined the possible role of miR-24 in the response of human TM cells to CMS. CMS induced the expression of miR-24 that led to the down regulation of the subtilisin-like proprotein convertase FURIN, which is known to play a major role in the processing of TGFβ1. FURIN was confirmed as a novel target of miR-24 by 3' UTR luciferase assay and western blot. Overexpression of miR-24 resulted in a significant decrease in activated TGFβ1. This effect was mimicked by down regulation of FURIN by siRNA. Conversely, inhibition of miR-24 expression with a specific antagomir led to a small but significant increase in TGFβ1. Furthermore, the increase in active TGFβ1 induced by CMS in HTM cells was prevented by miR-24. Altogether, our results suggest that miRNAs might contribute to the regulation of responses to CMS in TM cells. Specifically, miR-24 might play an important role in modulating the induction of TGFβ1 mediated by CMS through direct targeting of FURIN.
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Affiliation(s)
- Coralia Luna
- Department of Ophthalmology, Duke University, Durham, North Carolina 27710, USA
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45
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Johnstone M, Martin E, Jamil A. Pulsatile flow into the aqueous veins: manifestations in normal and glaucomatous eyes. Exp Eye Res 2011; 92:318-27. [PMID: 21440541 PMCID: PMC4535453 DOI: 10.1016/j.exer.2011.03.011] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Revised: 02/15/2011] [Accepted: 03/17/2011] [Indexed: 11/29/2022]
Abstract
The aqueous outflow system is unique because nowhere else can the pattern of flow of an extravascular fluid be directly observed as it returns to the vascular system. Such observations reveal that aqueous flow both from Schlemm’s canal into the aqueous veins and from the aqueous veins into the episcleral veins is pulsatile. Pulsatile aqueous flow mechanisms are observable in vivo not only in normal and but also in glaucomatous eyes. A series of specific patterns accompany the pulsatile mixing of aqueous with blood in the episcleral veins. These directly observable patterns of pulsatile flow are synchronous with intraocular pressure (IOP) transients induced by the cardiac pulse, blinking and eye movement. Patterns of pulsatile flow are altered by events that increase IOP such as pressure on the side of the eye, tonography and water drinking. Pulsatile flow stops when IOP is reduced below its resting level, but begins again when IOP returns to the resting level. Pulsatile flow reduction probably results from the intrinsic reduction of pulse amplitude at a lower IOP, and may thus provide a passive mechanism to maintain short-term homeostasis. Thus modulation of the pulsatile flow phenomenon appears to maintain a homeostatic IOP setpoint. Visible pulsatile flow abnormalities develop in glaucoma patients. Medications that reduce IOP through improvement in outflow do so through pulsatile flow mechanisms. Laboratory studies have demonstrated that cyclic stresses in outflow tissues alter signaling pathways, cytoskeletal responses, extracellular matrix composition and cytokine secretion. How physiologic pulse transients orchestrate cellular responses and how cellular responses identified in the laboratory may in turn regulate pulsatile aqueous outflow is unknown. Linkage of laboratory and in vivo observations await an improved understanding of how cellular and extracellular structures within the outflow system are able to generate an aqueous pulse wave. The purpose of the current report is to provide a summary of in vivo IOP-induced patterns of cyclic flow that can be used as part of a framework for interpretation of responses to cyclic stresses identified in the laboratory.
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Affiliation(s)
- Murray Johnstone
- Eye Institute, University of Washington, 1259 NE Pacific St., HSB RR-802, Box 356485, Seattle, WA 98195-6485, USA.
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46
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Stamer WD, Piwnica D, Jolas T, Carling RW, Cornell CL, Fliri H, Martos J, Pettit SN, Wang JW, Woodward DF. Cellular basis for bimatoprost effects on human conventional outflow. Invest Ophthalmol Vis Sci 2010; 51:5176-81. [PMID: 20435598 DOI: 10.1167/iovs.09-4955] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Bimatoprost is a widely used ocular hypotensive agent to treat glaucoma. It lowers intraocular pressure in humans by increasing both pressure-independent (uveoscleral) and pressure-dependent (conventional) aqueous humor outflow. The present study specifically examines bimatoprost effects on the cells that populate human outflow tissues. METHODS The authors tested for prostamide receptor activation in primary cultures of human trabecular meshwork (TM), Schlemm's canal (SC), and ciliary smooth muscle (CSM) cells using cellular dielectric spectroscopy (CDS). RESULTS The authors observed that bimatoprost produced an immediate and concentration-dependent increase in cell monolayer impedance for TM, SC, and CSM cells with EC(50) values of 4.3, 1.2, and 1.7 nM, respectively; corresponding to decreased cell contractility. Notably, in TM, SC, and CSM cells, bimatoprost was approximately equipotent to the selective FP receptor agonists fluprostenol and 17-phenyl PGF(2α). Bimatoprost effects were insensitive to cholera toxin and pertussis toxin but were abolished by phorbol 12-myristate 13-acetate pretreatment, suggesting Gq-involvement in cell signaling. The effects of bimatoprost on TM and SC cells were inhibited by the prostamide receptor antagonist AGN211334, with IC(50) values of 1.2 and 3.3 μM, respectively. Interestingly, AGN211334 behaved as an apparent inverse agonist in CDS assays involving TM cells but as a neutral prostamide antagonist with SC cells. CONCLUSIONS Taken together, results suggest that bimatoprost specifically activates receptors in both cell types of the human conventional outflow pathway to modify intraocular pressure. However, only TM cell monolayers appear to have autocrine, or agonist-independent, receptor signaling that is sensitive to a prostamide receptor antagonist.
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Affiliation(s)
- W Daniel Stamer
- Department of Ophthalmology and Vision Science, The University of Arizona, Tucson, Arizona 85711, USA.
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