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Karimi A, Aga M, Khan T, D'costa SD, Thaware O, White E, Kelley MJ, Gong H, Acott TS. Comparative analysis of traction forces in normal and glaucomatous trabecular meshwork cells within a 3D, active fluid-structure interaction culture environment. Acta Biomater 2024; 180:206-229. [PMID: 38641184 DOI: 10.1016/j.actbio.2024.04.021] [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: 12/20/2023] [Revised: 03/26/2024] [Accepted: 04/11/2024] [Indexed: 04/21/2024]
Abstract
This study presents a 3D in vitro cell culture model, meticulously 3D printed to replicate the conventional aqueous outflow pathway anatomical structure, facilitating the study of trabecular meshwork (TM) cellular responses under glaucomatous conditions. Glaucoma affects TM cell functionality, leading to extracellular matrix (ECM) stiffening, enhanced cell-ECM adhesion, and obstructed aqueous humor outflow. Our model, reconstructed from polyacrylamide gel with elastic moduli of 1.5 and 21.7 kPa, is based on serial block-face scanning electron microscopy images of the outflow pathway. It allows for quantifying 3D, depth-dependent, dynamic traction forces exerted by both normal and glaucomatous TM cells within an active fluid-structure interaction (FSI) environment. In our experimental design, we designed two scenarios: a control group with TM cells observed over 20 hours without flow (static setting), focusing on intrinsic cellular contractile forces, and a second scenario incorporating active FSI to evaluate its impact on traction forces (dynamic setting). Our observations revealed that active FSI results in higher traction forces (normal: 1.83-fold and glaucoma: 2.24-fold) and shear strains (normal: 1.81-fold and glaucoma: 2.41-fold), with stiffer substrates amplifying this effect. Glaucomatous cells consistently exhibited larger forces than normal cells. Increasing gel stiffness led to enhanced stress fiber formation in TM cells, particularly in glaucomatous cells. Exposure to active FSI dramatically altered actin organization in both normal and glaucomatous TM cells, particularly affecting cortical actin stress fiber arrangement. This model while preliminary offers a new method in understanding TM cell biomechanics and ECM stiffening in glaucoma, highlighting the importance of FSI in these processes. STATEMENT OF SIGNIFICANCE: This pioneering project presents an advanced 3D in vitro model, meticulously replicating the human trabecular meshwork's anatomy for glaucoma research. It enables precise quantification of cellular forces in a dynamic fluid-structure interaction, a leap forward from existing 2D models. This advancement promises significant insights into trabecular meshwork cell biomechanics and the stiffening of the extracellular matrix in glaucoma, offering potential pathways for innovative treatments. This research is positioned at the forefront of ocular disease study, with implications that extend to broader biomedical applications.
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Affiliation(s)
- Alireza Karimi
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, United States; Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR, United States.
| | - Mini Aga
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, United States
| | - Taaha Khan
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, United States
| | - Siddharth Daniel D'costa
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, United States
| | - Omkar Thaware
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, United States; Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR, United States
| | - Elizabeth White
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, United States
| | - Mary J Kelley
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, United States; Department Integrative Biosciences, School of Dentistry, Oregon Health & Science University, Portland, OR, United States
| | - Haiyan Gong
- Department of Ophthalmology, Boston University School of Medicine, Boston, MA, United States; Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA, United States
| | - Ted S Acott
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, United States; Department Chemical Physiology & Biochemistry, School of Medicine, Oregon Health & Science University, Portland, OR, United States
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Karimi A, Aga M, Khan T, D'costa SD, Cardenas-Riumallo S, Zelenitz M, Kelley MJ, Acott TS. Dynamic traction force in trabecular meshwork cells: A 2D culture model for normal and glaucomatous states. Acta Biomater 2024; 175:138-156. [PMID: 38151067 PMCID: PMC10843681 DOI: 10.1016/j.actbio.2023.12.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 12/10/2023] [Accepted: 12/20/2023] [Indexed: 12/29/2023]
Abstract
Glaucoma, which is associated with intraocular pressure (IOP) elevation, results in trabecular meshwork (TM) cellular dysfunction, leading to increased rigidity of the extracellular matrix (ECM), larger adhesion forces between the TM cells and ECM, and higher resistance to aqueous humor drainage. TM cells sense the mechanical forces due to IOP dynamic and apply multidimensional forces on the ECM. Recognizing the importance of cellular forces in modulating various cellular activities and development, this study is aimed to develop a 2D in vitro cell culture model to calculate the 3D, depth-dependent, dynamic traction forces, tensile/compressive/shear strain of the normal and glaucomatous human TM cells within a deformable polyacrylamide (PAM) gel substrate. Normal and glaucomatous human TM cells were isolated, cultured, and seeded on top of the PAM gel substrate with embedded FluoSpheres, spanning elastic moduli of 1.5 to 80 kPa. Sixteen-hour post-seeding live confocal microscopy in an incubator was conducted to Z-stack image the 3D displacement map of the FluoSpheres within the PAM gels. Combined with the known PAM gel stiffness, we ascertained the 3D traction forces in the gel. Our results revealed meaningfully larger traction forces in the glaucomatous TM cells compared to the normal TM cells, reaching depths greater than 10-µm in the PAM gel substrate. Stress fibers in TM cells increased with gel rigidity, but diminished when stiffness rose from 20 to 80 kPa. The developed 2D cell culture model aids in understanding how altered mechanical properties in glaucoma impact TM cell behavior and aqueous humor outflow resistance. STATEMENT OF SIGNIFICANCE: Glaucoma, a leading cause of irreversible blindness, is intricately linked to elevated intraocular pressures and their subsequent cellular effects. The trabecular meshwork plays a pivotal role in this mechanism, particularly its interaction with the extracellular matrix. This research unveils an advanced 2D in vitro cell culture model that intricately maps the complex 3D forces exerted by trabecular meshwork cells on the extracellular matrix, offering unparalleled insights into the cellular biomechanics at play in both healthy and glaucomatous eyes. By discerning the changes in these forces across varying substrate stiffness levels, we bridge the gap in understanding between cellular mechanobiology and the onset of glaucoma. The findings stand as a beacon for potential therapeutic avenues, emphasizing the gravity of cellular/extracellular matrix interactions in glaucoma's pathogenesis and setting the stage for targeted interventions in its early stages.
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Affiliation(s)
- Alireza Karimi
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA; Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR, USA.
| | - Mini Aga
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Taaha Khan
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Siddharth Daniel D'costa
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | | | - Meadow Zelenitz
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Mary J Kelley
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA; Department Integrative Biosciences, School of Dentistry, Oregon Health & Science University, Portland, OR, USA
| | - Ted S Acott
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA; Department Chemical Physiology & Biochemistry, School of Medicine, Oregon Health & Science University, Portland, OR, USA
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Youngblood H, Schoenlein PV, Pasquale LR, Stamer WD, Liu Y. Estrogen dysregulation, intraocular pressure, and glaucoma risk. Exp Eye Res 2023; 237:109725. [PMID: 37956940 PMCID: PMC10842791 DOI: 10.1016/j.exer.2023.109725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 10/20/2023] [Accepted: 11/08/2023] [Indexed: 11/19/2023]
Abstract
Characterized by optic nerve atrophy due to retinal ganglion cell (RGC) death, glaucoma is the leading cause of irreversible blindness worldwide. Of the major risk factors for glaucoma (age, ocular hypertension, and genetics), only elevated intraocular pressure (IOP) is modifiable, which is largely regulated by aqueous humor outflow through the trabecular meshwork. Glucocorticoids such as dexamethasone have long been known to elevate IOP and lead to glaucoma. However, several recent studies have reported that steroid hormone estrogen levels inversely correlate with glaucoma risk, and that variants in estrogen signaling genes have been associated with glaucoma. As a result, estrogen dysregulation may contribute to glaucoma pathogenesis, and estrogen signaling may protect against glaucoma. The mechanism for estrogen-related protection against glaucoma is not completely understood but likely involves both regulation of IOP homeostasis and neuroprotection of RGCs. Based upon its known activities, estrogen signaling may promote IOP homeostasis by affecting extracellular matrix turnover, focal adhesion assembly, actin stress fiber formation, mechanosensation, and nitric oxide production. In addition, estrogen receptors in the RGCs may mediate neuroprotective functions. As a result, the estrogen signaling pathway may offer a therapeutic target for both IOP control and neuroprotection. This review examines the evidence for a relationship between estrogen and IOP and explores the possible mechanisms by which estrogen maintains IOP homeostasis.
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Affiliation(s)
- Hannah Youngblood
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Patricia V Schoenlein
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA; Department of Radiology and Georgia Cancer Center, Augusta University, Augusta, GA, USA; Department of Surgery, Augusta University, Augusta, GA, USA
| | - Louis R Pasquale
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - W Daniel Stamer
- Department of Ophthalmology and Biomedical Engineering, Duke University, Durham, NC, USA
| | - Yutao Liu
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA; James and Jean Culver Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA, USA; Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA, USA.
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Wang T, Soundararajan A, Rabinowitz J, Jaiswal A, Osborne T, Pattabiraman PP. Identification of the novel role of sterol regulatory element binding proteins (SREBPs) in mechanotransduction and intraocular pressure regulation. FASEB J 2023; 37:e23248. [PMID: 37823226 PMCID: PMC10826798 DOI: 10.1096/fj.202301185r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 09/11/2023] [Accepted: 09/26/2023] [Indexed: 10/13/2023]
Abstract
Trabecular meshwork (TM) cells are contractile and mechanosensitive, and they aid in maintaining intraocular pressure (IOP) homeostasis. Lipids are attributed to modulating TM contractility, with poor mechanistic understanding. In this study using human TM cells, we identify the mechanosensing role of the transcription factors sterol regulatory element binding proteins (SREBPs) involved in lipogenesis. By constitutively activating SREBPs and pharmacologically inactivating SREBPs, we have mechanistically deciphered the attributes of SREBPs in regulating the contractile properties of TM. The pharmacological inhibition of SREBPs by fatostatin and molecular inactivation of SREBPs ex vivo and in vivo, respectively, results in significant IOP lowering. As a proof of concept, fatostatin significantly decreased the SREBPs responsive genes and enzymes involved in lipogenic pathways as well as the levels of the phospholipid, cholesterol, and triglyceride. Further, we show that fatostatin mitigated actin polymerization machinery and stabilization, and decreased ECM synthesis and secretion. We thus postulate that lowering lipogenesis in the TM outflow pathway can hold the key to lowering IOP by modifying the TM biomechanics.
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Affiliation(s)
- Ting Wang
- Glick Eye Institute, Department of Ophthalmology, Indiana University School of Medicine, 1160 West Michigan Street, Indianapolis, Indiana, 46202, United States of America
- Stark Neuroscience Research Institute, Medical Neuroscience Graduate Program, Indiana University School of Medicine, 320 W. 15th Street, Indiana, 46202, United States of America
| | - Avinash Soundararajan
- Glick Eye Institute, Department of Ophthalmology, Indiana University School of Medicine, 1160 West Michigan Street, Indianapolis, Indiana, 46202, United States of America
| | - Jeffrey Rabinowitz
- Department of Ophthalmology, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Anant Jaiswal
- Institute for Fundamental Biomedical Research, Department of Medicine and Biological Chemistry, Johns Hopkins University School of Medicine, St. Petersburg, Florida, 33701, United States of America
| | - Timothy Osborne
- Institute for Fundamental Biomedical Research, Department of Medicine and Biological Chemistry, Johns Hopkins University School of Medicine, St. Petersburg, Florida, 33701, United States of America
| | - Padmanabhan Paranji Pattabiraman
- Glick Eye Institute, Department of Ophthalmology, Indiana University School of Medicine, 1160 West Michigan Street, Indianapolis, Indiana, 46202, United States of America
- Stark Neuroscience Research Institute, Medical Neuroscience Graduate Program, Indiana University School of Medicine, 320 W. 15th Street, Indiana, 46202, United States of America
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Aboobakar IF, Collantes ERA, Hauser MA, Stamer WD, Wiggs JL. Rare protective variants and glaucoma-relevant cell stressors modulate Angiopoietin-like 7 expression. Hum Mol Genet 2023; 32:2523-2531. [PMID: 37220876 PMCID: PMC10360392 DOI: 10.1093/hmg/ddad083] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/10/2023] [Accepted: 05/11/2023] [Indexed: 05/25/2023] Open
Abstract
Rare missense and nonsense variants in the Angiopoietin-like 7 (ANGPTL7) gene confer protection from primary open-angle glaucoma (POAG), though the functional mechanism remains uncharacterized. Interestingly, a larger variant effect size strongly correlates with in silico predictions of increased protein instability (r = -0.98), suggesting that protective variants lower ANGPTL7 protein levels. Here, we show that missense and nonsense variants cause aggregation of mutant ANGPTL7 protein in the endoplasmic reticulum (ER) and decreased levels of secreted protein in human trabecular meshwork (TM) cells; a lower secreted:intracellular protein ratio strongly correlates with variant effects on intraocular pressure (r = 0.81). Importantly, accumulation of mutant protein in the ER does not increase expression of ER stress proteins in TM cells (P > 0.05 for all variants tested). Cyclic mechanical stress, a glaucoma-relevant physiologic stressor, also significantly lowers ANGPTL7 expression in primary cultures of human Schlemm's canal (SC) cells (-2.4-fold-change, P = 0.01). Collectively, these data suggest that the protective effects of ANGPTL7 variants in POAG stem from lower levels of secreted protein, which may modulate responses to physiologic and pathologic ocular cell stressors. Downregulation of ANGPTL7 expression may therefore serve as a viable preventative and therapeutic strategy for this common, blinding disease.
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Affiliation(s)
- Inas F Aboobakar
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA 02115, USA
| | - Edward Ryan A Collantes
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA 02115, USA
| | - Michael A Hauser
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC 27710, USA
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Biomedical Engineering, Duke University School of Medicine, Durham, NC 27710, USA
| | - Janey L Wiggs
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA 02115, USA
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Wang T, Soundararajan A, Rabinowitz J, Jaiswal A, Osborne T, Pattabiraman PP. Identification of the novel role of sterol regulatory element binding proteins (SREBPs) in mechanotransduction and intraocular pressure regulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.05.527136. [PMID: 37214961 PMCID: PMC10197526 DOI: 10.1101/2023.02.05.527136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Trabecular meshwork (TM) cells are highly contractile and mechanosensitive to aid in maintaining intraocular pressure (IOP) homeostasis. Lipids are attributed to modulating TM contractility with poor mechanistic understanding. In this study using human TM cells, we identify the mechanosensing role of the transcription factors sterol regulatory element binding proteins (SREBPs) involved in lipogenesis. By constitutively activating SREBPs and pharmacologically inactivating SREBPs, we have mechanistically deciphered the attributes of SREBPs in regulating the contractile properties of TM. The pharmacological inhibition of SREBPs by fatostatin and molecular inactivation of SREBPs ex vivo and in vivo respectively results in significant IOP lowering. As a proof of concept, fatostatin significantly decreased the SREBPs responsive genes and enzymes involved in lipogenic pathways as well as the levels of the phospholipid, cholesterol, and triglyceride. Further, we show that fatostatin mitigated actin polymerization machinery and stabilization, and decreased ECM synthesis and secretion. We thus postulate that lowering lipogenesis in the TM outflow pathway can hold the key to lowering IOP by modifying the TM biomechanics. Synopsis In this study, we show the role of lipogenic transcription factors sterol regulatory element binding proteins (SREBPs) in the regulation of intraocular pressure (IOP). ( Synopsis Figure - Created using Biorender.com ) SREBPs are involved in the sensing of changes in mechanical stress on the trabecular meshwork (TM). SREBPs aid in transducing the mechanical signals to induce actin polymerization and filopodia/lamellipodia formation.SREBPs inactivation lowered genes and enzymes involved in lipogenesis and modified lipid levels in TM.SREBPs activity is a critical regulator of ECM engagement to the matrix sites.Inactivation of SCAP-SREBP pathway lowered IOP via actin relaxation and decreasing ECM production and deposition in TM outflow pathway signifying a novel relationship between SREBP activation status and achieving IOP homeostasis.
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Goniotomy for Non-Infectious Uveitic Glaucoma in Children. J Clin Med 2023; 12:jcm12062200. [PMID: 36983202 PMCID: PMC10057863 DOI: 10.3390/jcm12062200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 03/06/2023] [Accepted: 03/10/2023] [Indexed: 03/14/2023] Open
Abstract
Secondary glaucoma is still a blinding complication in childhood uveitis, for which most commonly used surgical interventions (trabeculectomy or glaucoma drainage implant) involve multiple re-interventions and/or complications postoperatively. The goniotomy procedure has never been investigated in the current era, in which patients with pediatric uveitis receive biologics as immunosuppressive therapy for a prolonged period, with potential implications for the outcome. The purpose of the study is to evaluate the efficacy and safety of a goniotomy procedure in pediatric non-infectious uveitis in a retrospective, multicenter case series. The primary outcomes were the postoperative intraocular pressure (IOP), number of IOP-lowering medications, and success rate. Postoperative success was defined as 6 ≤ IOP ≤ 21 mmHg, without major complications or re-interventions. Fifteen eyes of ten children were included. Median age of the included patients at goniotomy was 7 years; median follow-up was 59 months. Median (interquartile range) IOP before surgery was 30 (26–34) mmHg with 4 (3–4) IOP-lowering medications. At 1, 2, and 5 years after goniotomy, median IOP was 15, 14, and 15 mmHg with 2 (0–2), 1 (0–2), and 0 (0–2) medications, respectively (p < 0.001 postoperatively versus preoperatively for all timepoints). Success rate was 100%, 93%, and 80% after 1, 2, and 5 years, respectively. There were no significant changes in visual acuity and uveitis activity or its treatment, and there were no major complications. Our results show that the goniotomy is an effective and safe surgery for children with uveitic glaucoma.
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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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Morleo M, Vieira HL, Pennekamp P, Palma A, Bento-Lopes L, Omran H, Lopes SS, Barral DC, Franco B. Crosstalk between cilia and autophagy: implication for human diseases. Autophagy 2023; 19:24-43. [PMID: 35613303 PMCID: PMC9809938 DOI: 10.1080/15548627.2022.2067383] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Macroautophagy/autophagy is a self-degradative process necessary for cells to maintain their energy balance during development and in response to nutrient deprivation. Autophagic processes are tightly regulated and have been found to be dysfunctional in several pathologies. Increasing experimental evidence points to the existence of an interplay between autophagy and cilia. Cilia are microtubule-based organelles protruding from the cell surface of mammalian cells that perform a variety of motile and sensory functions and, when dysfunctional, result in disorders known as ciliopathies. Indeed, selective autophagic degradation of ciliary proteins has been shown to control ciliogenesis and, conversely, cilia have been reported to control autophagy. Moreover, a growing number of players such as lysosomal and mitochondrial proteins are emerging as actors of the cilia-autophagy interplay. However, some of the published data on the cilia-autophagy axis are contradictory and indicate that we are just starting to understand the underlying molecular mechanisms. In this review, the current knowledge about this axis and challenges are discussed, as well as the implication for ciliopathies and autophagy-associated disorders.
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Affiliation(s)
- Manuela Morleo
- Telethon Institute of Genetics and Medicine (TIGEM), 80078, Pozzuoli, Italy,Department of Precision Medicine, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Helena L.A. Vieira
- CEDOC, NOVA Medical School, NMS, Universidade NOVA de Lisboa, Lisboa1169-056, Portugal,UCIBIO, Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal,Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Petra Pennekamp
- Department of General Pediatrics, University Hospital Münster, University of Münster, Münster48149, Germany,Member of the European Reference Networks ERN-LUNG, Lisbon, Portugal
| | - Alessandro Palma
- Department of Onco-hematology, Gene and Cell Therapy, Bambino Gesù Children’s Hospital - IRCCS, Rome, Italy
| | - Liliana Bento-Lopes
- CEDOC, NOVA Medical School, NMS, Universidade NOVA de Lisboa, Lisboa1169-056, Portugal
| | - Heymut Omran
- Department of General Pediatrics, University Hospital Münster, University of Münster, Münster48149, Germany,Member of the European Reference Networks ERN-LUNG, Lisbon, Portugal
| | - Susana S. Lopes
- CEDOC, NOVA Medical School, NMS, Universidade NOVA de Lisboa, Lisboa1169-056, Portugal,Member of the European Reference Networks ERN-LUNG, Lisbon, Portugal
| | - Duarte C. Barral
- CEDOC, NOVA Medical School, NMS, Universidade NOVA de Lisboa, Lisboa1169-056, Portugal
| | - Brunella Franco
- Telethon Institute of Genetics and Medicine (TIGEM), 80078, Pozzuoli, Italy,Medical Genetics, Department of Translational Medical Science, University of Naples “Federico II”, Naples, Italy,Scuola Superiore Meridionale, School for Advanced Studies, Naples, Italy,CONTACT Brunella Franco CEDOC, NOVA Medical School, NMS, Universidade NOVA de Lisboa, Lisboa1169-056, Portugal
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Du R, Li D, Zhu M, Zheng L, Ren K, Han D, Li L, Ji J, Fan Y. Cell senescence alters responses of porcine trabecular meshwork cells to shear stress. Front Cell Dev Biol 2022; 10:1083130. [DOI: 10.3389/fcell.2022.1083130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 11/04/2022] [Indexed: 11/23/2022] Open
Abstract
Mechanical microenvironment and cellular senescence of trabecular meshwork cells (TMCs) are suspected to play a vital role in primary open-angle glaucoma pathogenesis. However, central questions remain about the effect of shear stress on TMCs and how aging affects this process. We have investigated the effect of shear stress on the biomechanical properties and extracellular matrix regulation of normal and senescent TMCs. We found a more significant promotion of Fctin formation, a more obvious realignment of F-actin fibers, and a more remarkable increase in the stiffness of normal cells in response to the shear stress, in comparison with that of senescent cells. Further, as compared to normal cells, senescent cells show a reduced extracellular matrix turnover after shear stress stimulation, which might be attributed to the different phosphorylation levels of the extracellular signal-regulated kinase. Our results suggest that TMCs are able to sense and respond to the shear stress and cellular senescence undermines the mechanobiological response, which may lead to progressive failure of cellular TM function with age.
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Bikuna‐Izagirre M, Aldazabal J, Extramiana L, Moreno‐Montañés J, Carnero E, Paredes J. Technological advances in ocular trabecular meshwork in vitro models for glaucoma research. Biotechnol Bioeng 2022; 119:2698-2714. [PMID: 35836364 PMCID: PMC9543213 DOI: 10.1002/bit.28182] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Revised: 05/17/2022] [Accepted: 07/12/2022] [Indexed: 11/13/2022]
Abstract
Glaucoma is the leading cause of irreversible blindness worldwide and is characterized by the progressive degeneration of the optic nerve. Intraocular pressure (IOP), which is considered to be the main risk factor for glaucoma development, builds up in response to the resistance (resistance to what?) provided by the trabecular meshwork (TM) to aqueous humor (AH) outflow. Although the TM and its relationship to AH outflow have remained at the forefront of scientific interest, researchers remain uncertain regarding which mechanisms drive the deterioration of the TM. Current tissue-engineering fabrication techniques have come up with promising approaches to successfully recreate the TM. Nonetheless, more accurate models are needed to understand the factors that make glaucoma arise. In this review, we provide a chronological evaluation of the technological milestones that have taken place in the field of glaucoma research, and we conduct a comprehensive comparison of available TM fabrication technologies. Additionally, we also discuss AH perfusion platforms, since they are essential for the validation of these scaffolds, as well as pressure-outflow relationship studies and the discovery of new IOP-reduction therapies.
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Affiliation(s)
- Maria Bikuna‐Izagirre
- Tecnun School of EngineeringUniversity of NavarraSan SebastiánSpain
- Biomedical Engineering CenterUniversity of NavarraPamplonaSpain
| | - Javier Aldazabal
- Tecnun School of EngineeringUniversity of NavarraSan SebastiánSpain
- Biomedical Engineering CenterUniversity of NavarraPamplonaSpain
| | - Leire Extramiana
- Departamento de oftalmología ClínicaClínica Universidad de NavarraPamplonaEspaña
| | | | - Elena Carnero
- Departamento de oftalmología ClínicaClínica Universidad de NavarraPamplonaEspaña
| | - Jacobo Paredes
- Tecnun School of EngineeringUniversity of NavarraSan SebastiánSpain
- Biomedical Engineering CenterUniversity of NavarraPamplonaSpain
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12
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Shim MS, Liton PB. The physiological and pathophysiological roles of the autophagy lysosomal system in the conventional aqueous humor outflow pathway: More than cellular clean up. Prog Retin Eye Res 2022; 90:101064. [PMID: 35370083 PMCID: PMC9464695 DOI: 10.1016/j.preteyeres.2022.101064] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 03/09/2022] [Accepted: 03/25/2022] [Indexed: 10/18/2022]
Abstract
During the last few years, the autophagy lysosomal system is emerging as a central cellular pathway with roles in survival, acting as a housekeeper and stress response mechanism. Studies by our and other labs suggest that autophagy might play an essential role in maintaining aqueous humor outflow homeostasis, and that malfunction of autophagy in outflow pathway cells might predispose to ocular hypertension and glaucoma pathogenesis. In this review, we will collect the current knowledge and discuss the molecular mechanisms by which autophagy does or might regulate normal outflow pathway tissue function, and its response to different types of stressors (oxidative stress and mechanical stress). We will also discuss novel roles of autophagy and lysosomal enzymes in modulation of TGFβ signaling and ECM remodeling, and the link between dysregulated autophagy and cellular senescence. We will examine what we have learnt, using pre-clinical animal models about how dysregulated autophagy can contribute to disease and apply that to the current status of autophagy in human glaucoma. Finally, we will consider and discuss the challenges and the potential of autophagy as a therapeutic target for the treatment of ocular hypertension and glaucoma.
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Affiliation(s)
- Myoung Sup Shim
- Duke University, Department of Ophthalmology, Durham, NC, 27705, USA
| | - Paloma B Liton
- Duke University, Department of Ophthalmology, Durham, NC, 27705, USA.
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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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Dhamodaran K, Baidouri H, Nartey A, Staverosky J, Keller K, Acott T, Vranka J, Raghunathan V. Endogenous expression of Notch pathway molecules in human trabecular meshwork cells. Exp Eye Res 2022; 216:108935. [PMID: 35033558 PMCID: PMC8885976 DOI: 10.1016/j.exer.2022.108935] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/23/2021] [Accepted: 01/05/2022] [Indexed: 11/25/2022]
Abstract
PURPOSE Cells in the trabecular meshwork sense and respond to a myriad of physical forces through a process known as mechanotransduction. Whilst the effect of substratum stiffness or stretch on TM cells have been investigated in the context of transforming growth factor (TGF-β), Wnt and YAP/TAZ pathways, the role of Notch signaling, an evolutionarily conserved pathway, recently implicated in mechanotransduction, has not been investigated in trabecular meshwork (TM) cells. Here, we compare the endogenous expression of Notch pathway molecules in TM cells from glaucomatous and non-glaucomatous donors, segmental flow regions, and when subjected to cyclical strain, or grown on hydrogels of varying rigidity. METHODS Primary TM from glaucomatous (GTM), non-glaucomatous (NTM) donors, and from segmental flow regions [high flow (HF), low flow (LF)], were utilized between passages 2-6. Cells were (i) plated on tissue culture plastic, (ii) subjected to cyclical strain (6 h and 24 h), or (iii) cultured on 3 kPa and 80 kPa hydrogels. mRNA levels of Notch receptors/ligands/effectors in the TM cells was determined by qRT-PCR. Phagocytosis was determined as a function of substratum stiffness in NTM-HF/LF cells in the presence or absence of 100 nM Dexamethasone treatment. RESULTS Innate expression of Notch pathway genes were significantly overexpressed in GTM cells with no discernible differences observed between HF/LF cells in either NTM or GTM cells cultured on plastic substrates. With 6 h of cyclical strain, a subset of Notch pathway genes presented with altered expression. Expression of Notch receptors/ligands/receptors/inhibitors progressively declined with increasing stiffness and this correlated with phagocytic ability of NTM cells. Dexamethasone treatment decreased phagocytosis regardless of stiffness or cells isolated from segmental outflow regions. CONCLUSIONS We demonstrate here that the Notch expression in cultured TM cells differ intrinsically between GTM vs NTM, and by substratum cues (cyclical strain and stiffness). Of import, the most apparent differences in gene expression were observed as a function of substratum stiffness which closely followed phagocytic ability of cells. Interestingly, on soft substrates (mimicking normal TM stiffness) Notch expression and phagocytosis was highest, while both expression and phagocytosis was significantly lower on stiffer substrates (mimicking glaucomatous stiffness) regardless of DEX treatment. Such context dependent changes suggest Notch pathway may play differing roles in disease vs homeostasis. Studies focused on understanding the mechanistic role of Notch (if any) in outflow homeostasis are thus warranted.
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Affiliation(s)
- Kamesh Dhamodaran
- Department of Basic Sciences, College of Optometry, University of Houston, Houston, TX, USA
| | - Hasna Baidouri
- Department of Basic Sciences, College of Optometry, University of Houston, Houston, TX, USA
| | - Andrews Nartey
- Department of Basic Sciences, College of Optometry, University of Houston, Houston, TX, USA
| | - Julia Staverosky
- Casey Eye Institute, Oregon Health and Sciences University, Portland, OR, USA
| | - Kate Keller
- Casey Eye Institute, Oregon Health and Sciences University, Portland, OR, USA
| | - Ted Acott
- Casey Eye Institute, Oregon Health and Sciences University, Portland, OR, USA
| | - Janice Vranka
- Casey Eye Institute, Oregon Health and Sciences University, Portland, OR, USA
| | - VijayKrishna Raghunathan
- Department of Basic Sciences, College of Optometry, University of Houston, Houston, TX, USA,Department of Biomedical Engineering, University of Houston, Houston, TX, USA,Correspondence should be sent to: VijayKrishna Raghunathan, Ph.D., University of Houston, College of Optometry, 4901 Calhoun Rd, Houston, TX, 77204, Phone: (713)-743-8331,
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16
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Lamont HC, Masood I, Grover LM, El Haj AJ, Hill LJ. Fundamental Biomaterial Considerations in the Development of a 3D Model Representative of Primary Open Angle Glaucoma. Bioengineering (Basel) 2021; 8:bioengineering8110147. [PMID: 34821713 PMCID: PMC8615171 DOI: 10.3390/bioengineering8110147] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 10/15/2021] [Accepted: 10/17/2021] [Indexed: 12/12/2022] Open
Abstract
Glaucoma is a leading cause of irreversible blindness globally, with primary open angle glaucoma (POAG) being the most common subset. Raised intraocular pressure is an important risk factor for POAG and is caused by a reduction in aqueous humour (AqH) outflow due to dysfunctional cellular and matrix dynamics in the eye’s main drainage site, the trabecular meshwork (TM) and Schlemm’s canal (SC). The TM/SC are highly specialised tissues that regulate AqH outflow; however, their exact mechanisms of AqH outflow control are still not fully understood. Emulating physiologically relevant 3D TM/S in vitro models poses challenges to accurately mimic the complex biophysical and biochemical cues that take place in healthy and glaucomatous TM/SC in vivo. With development of such models still in its infancy, there is a clear need for more well-defined approaches that will accurately contrast the two central regions that become dysfunctional in POAG; the juxtacanalicular tissue (JCT) region of the TM and inner wall endothelia of the Schlemm’s canal (eSC). This review will discuss the unique biological and biomechanical characteristics that are thought to influence AqH outflow and POAG progression. Further consideration into fundamental biomaterial attributes for the formation of a biomimetic POAG/AqH outflow model will also be explored for future success in pre-clinical drug discovery and disease translation.
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Affiliation(s)
- Hannah C. Lamont
- School of Biomedical Sciences, Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (H.C.L.); (I.M.)
- School of Chemical Engineering, Healthcare Technologies Institute, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (L.M.G.); (A.J.E.H.)
| | - Imran Masood
- School of Biomedical Sciences, Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (H.C.L.); (I.M.)
| | - Liam M. Grover
- School of Chemical Engineering, Healthcare Technologies Institute, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (L.M.G.); (A.J.E.H.)
| | - Alicia J. El Haj
- School of Chemical Engineering, Healthcare Technologies Institute, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (L.M.G.); (A.J.E.H.)
| | - Lisa J. Hill
- School of Biomedical Sciences, Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (H.C.L.); (I.M.)
- Correspondence:
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17
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Primary cilia and the reciprocal activation of AKT and SMAD2/3 regulate stretch-induced autophagy in trabecular meshwork cells. Proc Natl Acad Sci U S A 2021; 118:2021942118. [PMID: 33753495 DOI: 10.1073/pnas.2021942118] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Activation of autophagy is one of the responses elicited by high intraocular pressure (IOP) and mechanical stretch in trabecular meshwork (TM) cells. However, the mechanosensor and the molecular mechanisms by which autophagy is induced by mechanical stretch in these or other cell types is largely unknown. Here, we have investigated the mechanosensor and downstream signaling pathway that regulate cyclic mechanical stretch (CMS)-induced autophagy in TM cells. We report that primary cilia act as a mechanosensor for CMS-induced autophagy and identified a cross-regulatory talk between AKT1 and noncanonical SMAD2/3 signaling as critical components of primary cilia-mediated activation of autophagy by mechanical stretch. Furthermore, we demonstrated the physiological significance of our findings in ex vivo perfused eyes. Removal of primary cilia disrupted the homeostatic IOP compensatory response and prevented the increase in LC3-II protein levels in response to elevated pressure challenge, strongly supporting a role of primary cilia-mediated autophagy in regulating IOP homeostasis.
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18
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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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19
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Nair KS, Srivastava C, Brown RV, Koli S, Choquet H, Kang HS, Kuo YM, Grimm SA, Sutherland C, Badea A, Johnson GA, Zhao Y, Yin J, Okamoto K, Clark G, Borrás T, Zode G, Kizhatil K, Chakrabarti S, John SWM, Jorgenson E, Jetten AM. GLIS1 regulates trabecular meshwork function and intraocular pressure and is associated with glaucoma in humans. Nat Commun 2021; 12:4877. [PMID: 34385434 PMCID: PMC8361148 DOI: 10.1038/s41467-021-25181-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 07/21/2021] [Indexed: 01/01/2023] Open
Abstract
Chronically elevated intraocular pressure (IOP) is the major risk factor of primary open-angle glaucoma, a leading cause of blindness. Dysfunction of the trabecular meshwork (TM), which controls the outflow of aqueous humor (AqH) from the anterior chamber, is the major cause of elevated IOP. Here, we demonstrate that mice deficient in the Krüppel-like zinc finger transcriptional factor GLI-similar-1 (GLIS1) develop chronically elevated IOP. Magnetic resonance imaging and histopathological analysis reveal that deficiency in GLIS1 expression induces progressive degeneration of the TM, leading to inefficient AqH drainage from the anterior chamber and elevated IOP. Transcriptome and cistrome analyses identified several glaucoma- and extracellular matrix-associated genes as direct transcriptional targets of GLIS1. We also identified a significant association between GLIS1 variant rs941125 and glaucoma in humans (P = 4.73 × 10-6), further supporting a role for GLIS1 into glaucoma etiology. Our study identifies GLIS1 as a critical regulator of TM function and maintenance, AqH dynamics, and IOP.
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Affiliation(s)
- K Saidas Nair
- Department of Ophthalmology and Department of Anatomy, School of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Chitrangda Srivastava
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA
| | - Robert V Brown
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA
| | - Swanand Koli
- Department of Ophthalmology, School of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Hélène Choquet
- Kaiser Permanente Northern California, Division of Research, Oakland, CA, USA
| | - Hong Soon Kang
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA
| | - Yien-Ming Kuo
- Department of Ophthalmology, School of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Sara A Grimm
- Integrative Bioinformatics Support Group, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA
| | - Caleb Sutherland
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA
| | - Alexandra Badea
- Center for In Vivo Microscopy, Department of Radiology, Duke University, Durham, NC, USA
| | - G Allan Johnson
- Center for In Vivo Microscopy, Department of Radiology, Duke University, Durham, NC, USA
| | - Yin Zhao
- Department of Ophthalmology, School of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Jie Yin
- Kaiser Permanente Northern California, Division of Research, Oakland, CA, USA
| | - Kyoko Okamoto
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA
| | | | - Terete Borrás
- Department of Ophthalmology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Gulab Zode
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, USA
| | | | | | - Simon W M John
- The Jackson Laboratory, Bar Harbor, ME, USA
- Howard Hughes Medical Institute, Mortimer B. Zuckerman Mind Brain Behavior Institute, Department of Ophthalmology, Columbia University, New York, NY, USA
| | | | - Anton M Jetten
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA.
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20
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Patel PD, Chen YL, Kasetti RB, Maddineni P, Mayhew W, Millar JC, Ellis DZ, Sonkusare SK, Zode GS. Impaired TRPV4-eNOS signaling in trabecular meshwork elevates intraocular pressure in glaucoma. Proc Natl Acad Sci U S A 2021; 118:e2022461118. [PMID: 33853948 PMCID: PMC8072326 DOI: 10.1073/pnas.2022461118] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Primary Open Angle Glaucoma (POAG) is the most common form of glaucoma that leads to irreversible vision loss. Dysfunction of trabecular meshwork (TM) tissue, a major regulator of aqueous humor (AH) outflow resistance, is associated with intraocular pressure (IOP) elevation in POAG. However, the underlying pathological mechanisms of TM dysfunction in POAG remain elusive. In this regard, transient receptor potential vanilloid 4 (TRPV4) cation channels are known to be important Ca2+ entry pathways in multiple cell types. Here, we provide direct evidence supporting Ca2+ entry through TRPV4 channels in human TM cells and show that TRPV4 channels in TM cells can be activated by increased fluid flow/shear stress. TM-specific TRPV4 channel knockout in mice elevated IOP, supporting a crucial role for TRPV4 channels in IOP regulation. Pharmacological activation of TRPV4 channels in mouse eyes also improved AH outflow facility and lowered IOP. Importantly, TRPV4 channels activated endothelial nitric oxide synthase (eNOS) in TM cells, and loss of eNOS abrogated TRPV4-induced lowering of IOP. Remarkably, TRPV4-eNOS signaling was significantly more pronounced in TM cells compared to Schlemm's canal cells. Furthermore, glaucomatous human TM cells show impaired activity of TRPV4 channels and disrupted TRPV4-eNOS signaling. Flow/shear stress activation of TRPV4 channels and subsequent NO release were also impaired in glaucomatous primary human TM cells. Together, our studies demonstrate a central role for TRPV4-eNOS signaling in IOP regulation. Our results also provide evidence that impaired TRPV4 channel activity in TM cells contributes to TM dysfunction and elevated IOP in glaucoma.
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Affiliation(s)
- Pinkal D Patel
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107
| | - Yen-Lin Chen
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908
| | - Ramesh B Kasetti
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107
| | - Prabhavathi Maddineni
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107
| | - William Mayhew
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107
| | - J Cameron Millar
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107
| | - Dorette Z Ellis
- Department of Pharmaceutical Sciences, North Texas Eye Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107
| | - Swapnil K Sonkusare
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908;
- Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Gulab S Zode
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107;
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21
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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: 23] [Impact Index Per Article: 7.7] [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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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: 8] [Impact Index Per Article: 2.7] [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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Yarishkin O, Phuong TTT, Baumann JM, De Ieso ML, Vazquez-Chona F, Rudzitis CN, Sundberg C, Lakk M, Stamer WD, Križaj D. Piezo1 channels mediate trabecular meshwork mechanotransduction and promote aqueous fluid outflow. J Physiol 2021; 599:571-592. [PMID: 33226641 PMCID: PMC7849624 DOI: 10.1113/jp281011] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 11/17/2020] [Indexed: 01/13/2023] Open
Abstract
KEY POINTS Trabecular meshwork (TM) is a highly mechanosensitive tissue in the eye that regulates intraocular pressure through the control of aqueous humour drainage. Its dysfunction underlies the progression of glaucoma but neither the mechanisms through which TM cells sense pressure nor their role in aqueous humour outflow are understood at the molecular level. We identified the Piezo1 channel as a key TM transducer of tensile stretch, shear flow and pressure. Its activation resulted in intracellular signals that altered organization of the cytoskeleton and cell-extracellular matrix contacts and modulated the trabecular component of aqueous outflow whereas another channel, TRPV4, mediated a delayed mechanoresponse. This study helps elucidate basic mechanotransduction properties that may contribute to intraocular pressure regulation in the vertebrate eye. ABSTRACT Chronic elevations in intraocular pressure (IOP) can cause blindness by compromising the function of trabecular meshwork (TM) cells in the anterior eye, but how these cells sense and transduce pressure stimuli is poorly understood. Here, we demonstrate functional expression of two mechanically activated channels in human TM cells. Pressure-induced cell stretch evoked a rapid increase in transmembrane current that was inhibited by antagonists of the mechanogated channel Piezo1, Ruthenium Red and GsMTx4, and attenuated in Piezo1-deficient cells. The majority of TM cells exhibited a delayed stretch-activated current that was mediated independently of Piezo1 by TRPV4 (transient receptor potential cation channel, subfamily V, member 4) channels. Piezo1 functions as the principal TM transducer of physiological levels of shear stress, with both shear and the Piezo1 agonist Yoda1 increasing the number of focal cell-matrix contacts. Analysis of TM-dependent fluid drainage from the anterior eye showed significant inhibition by GsMTx4. Collectively, these results suggest that TM mechanosensitivity utilizes kinetically, regulatory and functionally distinct pressure transducers to inform the cells about force-sensing contexts. Piezo1-dependent control of shear flow sensing, calcium homeostasis, cytoskeletal dynamics and pressure-dependent outflow suggests potential for a novel therapeutic target in treating glaucoma.
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Affiliation(s)
- Oleg Yarishkin
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
| | - Tam T T Phuong
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
| | - Jackson M Baumann
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
| | - Michael L De Ieso
- Duke Eye Center, Duke University School of Medicine, Durham, NC, USA
| | - Felix Vazquez-Chona
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
| | - Christopher N Rudzitis
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
| | - Chad Sundberg
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
| | - Monika Lakk
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
| | - W Daniel Stamer
- Duke Eye Center, Duke University School of Medicine, Durham, NC, USA
| | - David Križaj
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT, USA
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24
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Cathepsin B Localizes in the Caveolae and Participates in the Proteolytic Cascade in Trabecular Meshwork Cells. Potential New Drug Target for the Treatment of Glaucoma. J Clin Med 2020; 10:jcm10010078. [PMID: 33379277 PMCID: PMC7795952 DOI: 10.3390/jcm10010078] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/17/2020] [Accepted: 12/24/2020] [Indexed: 12/13/2022] Open
Abstract
Extracellular matrix (ECM) deposition in the trabecular meshwork (TM) is one of the hallmarks of glaucoma, a group of human diseases and leading cause of permanent blindness. The molecular mechanisms underlying ECM deposition in the glaucomatous TM are not known, but it is presumed to be a consequence of excessive synthesis of ECM components, decreased proteolytic degradation, or both. Targeting ECM deposition might represent a therapeutic approach to restore outflow facility in glaucoma. Previous work conducted in our laboratory identified the lysosomal enzyme cathepsin B (CTSB) to be expressed on the cellular surface and to be secreted into the culture media in trabecular meshwork (TM) cells. Here, we further investigated the role of CTSB on ECM remodeling and outflow physiology in vitro and in CSTBko mice. Our results indicate that CTSB localizes in the caveolae and participates in the pericellular degradation of ECM in TM cells. We also report here a novel role of CTSB in regulating the expression of PAI-1 and TGFβ/Smad signaling in TM cells vitro and in vivo in CTSBko mice. We propose enhancing CTSB activity as a novel therapeutic target to attenuate fibrosis and ECM deposition in the glaucomatous outflow pathway.
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25
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Reina-Torres E, De Ieso ML, Pasquale LR, Madekurozwa M, van Batenburg-Sherwood J, Overby DR, Stamer WD. The vital role for nitric oxide in intraocular pressure homeostasis. Prog Retin Eye Res 2020; 83:100922. [PMID: 33253900 DOI: 10.1016/j.preteyeres.2020.100922] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 11/13/2020] [Accepted: 11/23/2020] [Indexed: 02/07/2023]
Abstract
Catalyzed by endothelial nitric oxide (NO) synthase (eNOS) activity, NO is a gaseous signaling molecule maintaining endothelial and cardiovascular homeostasis. Principally, NO regulates the contractility of vascular smooth muscle cells and permeability of endothelial cells in response to either biochemical or biomechanical cues. In the conventional outflow pathway of the eye, the smooth muscle-like trabecular meshwork (TM) cells and Schlemm's canal (SC) endothelium control aqueous humor outflow resistance, and therefore intraocular pressure (IOP). The mechanisms by which outflow resistance is regulated are complicated, but NO appears to be a key player as enhancement or inhibition of NO signaling dramatically affects outflow function; and polymorphisms in NOS3, the gene that encodes eNOS modifies the relation between various environmental exposures and glaucoma. Based upon a comprehensive review of past foundational studies, we present a model whereby NO controls a feedback signaling loop in the conventional outflow pathway that is sensitive to changes in IOP and its oscillations. Thus, upon IOP elevation, the outflow pathway tissues distend, and the SC lumen narrows resulting in increased SC endothelial shear stress and stretch. In response, SC cells upregulate the production of NO, relaxing neighboring TM cells and increasing permeability of SC's inner wall. These IOP-dependent changes in the outflow pathway tissues reduce the resistance to aqueous humor drainage and lower IOP, which, in turn, diminishes the biomechanical signaling on SC. Similar to cardiovascular pathogenesis, dysregulation of the eNOS/NO system leads to dysfunctional outflow regulation and ocular hypertension, eventually resulting in primary open-angle glaucoma.
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Affiliation(s)
| | | | - Louis R Pasquale
- Eye and Vision Research Institute of New York Eye and Ear Infirmary at Mount Sinai, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | | | | | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, UK.
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC, USA.
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26
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Lu R, Soden PA, Lee E. Tissue-Engineered Models for Glaucoma Research. MICROMACHINES 2020; 11:mi11060612. [PMID: 32599818 PMCID: PMC7345325 DOI: 10.3390/mi11060612] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 06/21/2020] [Accepted: 06/22/2020] [Indexed: 12/20/2022]
Abstract
Glaucoma is a group of optic neuropathies characterized by the progressive degeneration of retinal ganglion cells (RGCs). Patients with glaucoma generally experience elevations in intraocular pressure (IOP), followed by RGC death, peripheral vision loss and eventually blindness. However, despite the substantial economic and health-related impact of glaucoma-related morbidity worldwide, the surgical and pharmacological management of glaucoma is still limited to maintaining IOP within a normal range. This is in large part because the underlying molecular and biophysical mechanisms by which glaucomatous changes occur are still unclear. In the present review article, we describe current tissue-engineered models of the intraocular space that aim to advance the state of glaucoma research. Specifically, we critically evaluate and compare both 2D and 3D-culture models of the trabecular meshwork and nerve fiber layer, both of which are key players in glaucoma pathophysiology. Finally, we point out the need for novel organ-on-a-chip models of glaucoma that functionally integrate currently available 3D models of the retina and the trabecular outflow pathway.
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Affiliation(s)
- Renhao Lu
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA;
| | - Paul A. Soden
- College of Human Ecology, Cornell University, Ithaca, NY 14853, USA;
| | - Esak Lee
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA;
- Correspondence: ; Tel.: +1-607-255-8491
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27
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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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28
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Sherwood JM, Stamer WD, Overby DR. A model of the oscillatory mechanical forces in the conventional outflow pathway. J R Soc Interface 2020; 16:20180652. [PMID: 30958169 PMCID: PMC6364644 DOI: 10.1098/rsif.2018.0652] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Intraocular pressure is regulated by mechanosensitive cells within the conventional outflow pathway, the primary route of aqueous humour drainage from the eye. However, the characteristics of the forces acting on those cells are poorly understood. We develop a model that describes flow through the conventional outflow pathway, including the trabecular meshwork (TM) and Schlemm’s canal (SC). Accounting for the ocular pulse, we estimate the time-varying shear stress on SC endothelium and strain on the TM. We consider a range of outflow resistances spanning normotensive to hypertensive conditions. Over this range, the SC shear stress increases significantly and becomes highly oscillatory. TM strain also increases, but with negligible oscillations. Interestingly, TM strain responds more to changes in outflow resistance around physiological values, while SC shear stress responds more to elevated levels of resistance. A modest increase in TM stiffness, as observed in glaucoma, suppresses TM strain and practically eliminates the influence of outflow resistance on SC shear stress. As SC and TM cells respond to mechanical stimulation by secreting factors that modulate outflow resistance, our model provides insight regarding the potential role of SC shear and TM strain as mechanosensory cues for homeostatic regulation of outflow resistance and hence intraocular pressure.
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Affiliation(s)
- Joseph M Sherwood
- 1 Department of Bioengineering, Imperial College London , London , UK
| | - W Daniel Stamer
- 2 Department of Ophthalmology, Duke University , Durham, NC , USA
| | - Darryl R Overby
- 1 Department of Bioengineering, Imperial College London , London , UK
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29
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Elevated pressure influences relative distribution of segmental regions of the trabecular meshwork. Exp Eye Res 2019; 190:107888. [PMID: 31786158 DOI: 10.1016/j.exer.2019.107888] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 11/21/2019] [Accepted: 11/28/2019] [Indexed: 11/20/2022]
Abstract
Elevated intraocular pressure (IOP) is the primary risk factor for glaucoma and is the only treatable feature of the disease. There is a correlation between elevated pressure and homeostatic reductions in the aqueous humor outflow resistance via changes in the extracellular matrix of the trabecular meshwork. It is unclear how these extracellular matrix changes affect segmental patterns of aqueous humor outflow, nor do we understand their causal relationship. The goal of this study was to determine whether there are changes in the segmental outflow regions with perfusion in normal eyes, and whether these regions change during the IOP homeostatic response to elevated pressure. Using human anterior segment perfusion organ culture, we measured the amount of high flow (HF), intermediate flow (MF), and low flow (LF) regions before and after 7 days of perfusion at either physiologic pressure ("1x") or at elevated pressure ("2x"). We found a small but significant decrease in the amount of HF regions over 7 days perfusion at 1x pressure, and a twofold increase in the amount of MF regions over 7 days perfusion at 2x pressure. Small positional differences, or shifts in the specific location of HF, MF, or LF, occurred on a per eye basis and were not found to be statistically significant across biological replicates. Differences in the amount of segmental flow regions of contralateral eyes flowed at 1x pressure for 7 days were small and not statistically significant. These results demonstrate that perfusion at physiologic pressure had little effect on the distribution and amount of HF, MF and LF regions. However, the overall amount of MF regions is significantly increased in response to perfusion at elevated pressure during IOP homeostatic resistance adjustment. The amount of both HF and LF regions was decreased accordingly suggesting a coordinated response in the TM to elevated pressure.
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30
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Macher T, Häberle H, Wächter J, Thannhäuser C, Aurich H, Pham DT. Trabecular microbypass stents as minimally invasive approach after conventional glaucoma filtration surgery. J Cataract Refract Surg 2019; 44:50-55. [PMID: 29502617 DOI: 10.1016/j.jcrs.2017.10.039] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 10/22/2017] [Accepted: 10/24/2017] [Indexed: 11/27/2022]
Abstract
PURPOSE To evaluate long-term efficacy and safety of 2 trabecular microbypass stents in patients with advanced primary open-angle glaucoma (POAG) and insufficient intraocular pressure (IOP) after previous filtration surgery. SETTING Vivantes Klinikum Neukölln, Augenklinik, Berlin, Germany. DESIGN Retrospective case series. METHODS Eyes with uncontrolled and advanced POAG since 2014 were assessed. All eyes previously had at least 1 filtration surgery procedure. The anatomical landmarks and configuration of the anterior chamber angle had to be identified easily. Two iStents were placed nasally into Schlemm canal. RESULTS The study comprised 42 patients (42 eyes); 18 eyes had 1 previous glaucoma filtration surgery. During the follow-up of 12 months, the mean IOP in cases of primary failure of filtration surgery decreased from preoperative 23.8 mm Hg ± 3.9 (SD) to 15.2 ± 2.7 mm Hg. For cases with more than 1 previous filtration surgery, the mean IOP decreased from preoperative 26.1 ± 5.7 mm Hg to 16.3 ± 3.3 mm Hg. Medications were reduced from 2.7 ± 0.9 to 2.0 ± 1.1. No intraoperative or perioperative complications occurred. CONCLUSIONS For eyes with previous filtration surgery and medically uncontrolled IOP, the implantation of 2 stents provided a minimally invasive and safe reduction of mean IOP to less than 18 mm Hg at 12 months. The number of medications was also reduced.
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Affiliation(s)
- Thomas Macher
- From the Vivantes Klinikum Neukölln (Macher, Häberle, Thannhäuser, Aurich, Pham), Department of Ophthalmology and Augenklinik Berlin-Marzahn (Wächter), Department of Ophthalmology, Berlin, Germany.
| | - Heike Häberle
- From the Vivantes Klinikum Neukölln (Macher, Häberle, Thannhäuser, Aurich, Pham), Department of Ophthalmology and Augenklinik Berlin-Marzahn (Wächter), Department of Ophthalmology, Berlin, Germany
| | - Juliane Wächter
- From the Vivantes Klinikum Neukölln (Macher, Häberle, Thannhäuser, Aurich, Pham), Department of Ophthalmology and Augenklinik Berlin-Marzahn (Wächter), Department of Ophthalmology, Berlin, Germany
| | - Carsten Thannhäuser
- From the Vivantes Klinikum Neukölln (Macher, Häberle, Thannhäuser, Aurich, Pham), Department of Ophthalmology and Augenklinik Berlin-Marzahn (Wächter), Department of Ophthalmology, Berlin, Germany
| | - Henning Aurich
- From the Vivantes Klinikum Neukölln (Macher, Häberle, Thannhäuser, Aurich, Pham), Department of Ophthalmology and Augenklinik Berlin-Marzahn (Wächter), Department of Ophthalmology, Berlin, Germany
| | - Duy-Thoai Pham
- From the Vivantes Klinikum Neukölln (Macher, Häberle, Thannhäuser, Aurich, Pham), Department of Ophthalmology and Augenklinik Berlin-Marzahn (Wächter), Department of Ophthalmology, Berlin, Germany
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31
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Ho LTY, Skiba N, Ullmer C, Rao PV. Lysophosphatidic Acid Induces ECM Production via Activation of the Mechanosensitive YAP/TAZ Transcriptional Pathway in Trabecular Meshwork Cells. Invest Ophthalmol Vis Sci 2019; 59:1969-1984. [PMID: 29677358 PMCID: PMC5896423 DOI: 10.1167/iovs.17-23702] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Purpose Lysophosphatidic acid (LPA), a bioactive lipid, has been shown to increase resistance to aqueous humor outflow (AH) through the trabecular meshwork (TM). The molecular basis for this response of the TM to LPA, however, is not completely understood. In this study, we explored the possible involvement of mechanosensitive Yes-associated protein (YAP) and its paralog, transcriptional coactivator with PDZ-binding domain (TAZ), transcriptional activation in extracellular matrix (ECM) production by LPA-induced contractile activity in human TM cells (HTM). Methods The responsiveness of genes encoding LPA receptors (LPARs), LPA hydrolyzing lipid phosphate phosphatases (LPPs), and the LPA-generating autotaxin (ATX) to cyclic mechanical stretch in HTM cells, was evaluated by RT-quantitative (q)PCR. The effects of LPA and LPA receptor antagonists on actomyosin contractile activity, activation of YAP/TAZ, and levels of connective tissue growth factor (CTGF), and Cyr61 and ECM proteins in HTM cells were determined by immunoblotting, mass spectrometry, and immunofluorescence analyses. Results Cyclic mechanical stretch significantly increased the expression of several types of LPARs, LPP1, and ATX in HTM cells. LPA and LPA receptor–dependent contractile activity led to increases in both, the protein levels and activation of YAP/TAZ, and increased the levels of CTGF, Cyr61, α-smooth muscle actin (α–SMA), and ECM proteins in HTM cells. Conclusions The results of this study reveal that LPA and its receptors stimulate YAP/TAZ transcriptional activity in HTM cells by modulating cellular contractile tension, and augment expression of CTGF that in turn leads to increased production of ECM. Therefore, YAP/TAZ-induced increases in CTGF and ECM production could be an important molecular mechanism underlying LPA-induced resistance to AH outflow and ocular hypertension.
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Affiliation(s)
- Leona T Y Ho
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States
| | - Nikolai Skiba
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States
| | - Christoph Ullmer
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland
| | - Ponugoti Vasantha Rao
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States.,Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina, United States
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Li G, Torrejon KY, Unser AM, Ahmed F, Navarro ID, Baumgartner RA, Albers DS, Stamer WD. Trabodenoson, an Adenosine Mimetic With A1 Receptor Selectivity Lowers Intraocular Pressure by Increasing Conventional Outflow Facility in Mice. Invest Ophthalmol Vis Sci 2018; 59:383-392. [PMID: 29346804 PMCID: PMC5774255 DOI: 10.1167/iovs.17-23212] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To evaluate the relationship between the IOP-lowering effect of trabodenoson and the associated structural and functional changes in the trabecular meshwork (TM). Methods Six independent cohorts of young and aged mice were exposed to three different topical once-a-day formulations of trabodenoson and eyes were compared to those treated with placebo drops. IOP was measured daily just before drug administration using rebound tonometry. Outflow facility was measured in enucleated eyes. Flow patterns and morphology of conventional outflow tissues were monitored using tracer beads and standard histology, respectively. In parallel, three-dimensional human TM tissue constructs (3D-HTM) were grown and used in experiments to test effect of trabodenoson on the expression of collagen IV, fibronectin, matrix metalloproteinase (MMP)-2 and MMP-14 plus MMP-2 activity. Results Topical administration of trabodenoson significantly lowered IOP on every day tested, up to 7 days. After 2 days of treatment, outflow facility increased by 26% in aged mice and 30% overall (young and aged mice), which was significantly different from vehicle (P < 0.05). Outflow facility was 15% higher than controls after 7 days of treatment (P = 0.07). While gross morphology was not affected by treatment, the intensity of tracer bead distribution increased by day 7 (P = 0.05). Parallel experiments in 3D-HTM showed that trabodenoson treatment significantly increased MMP-2 activity and MMP-14 abundance, while decreasing fibronectin and collagen IV expression. Conclusions Trabodenoson alters ECM turnover by TM cells and increases conventional outflow facility, which accounts for its ability to lower IOP in young and aged mice.
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Affiliation(s)
- Guorong Li
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | | | - Andrea M Unser
- Glauconix Biosciences, Inc., Albany, New York, United States
| | - Feryan Ahmed
- Glauconix Biosciences, Inc., Albany, New York, United States
| | - Iris D Navarro
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | | | - David S Albers
- Inotek Pharmaceuticals Corporation, Lexington, Massachusetts, United States
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
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Ohia SE, Njie-Mbye YF, Robinson J, Mitchell L, Mckoy M, Opere CA, Sharif NA. Serotonin-2B/2C Receptors Mediate Bovine Ciliary Muscle Contraction: Role in Intraocular Pressure Regulation. J Ocul Pharmacol Ther 2018; 34:70-75. [PMID: 29364761 DOI: 10.1089/jop.2017.0123] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
PURPOSE To study the pharmacological profile of the serotonin (5-hydroxytryptamine [5-HT]) receptor subtype mediating contractions in bovine isolated ciliary muscles. METHODS Ciliary muscle strips were isolated from bovine eyeballs and mounted in organ baths containing aerated (95% O2, 5% CO2) Krebs buffer solution maintained at 37°C. Each muscle strip was attached at 1 end to a Grass Force-displacement Transducer connected to a Polyview Computer System for recording changes in isometric tension. After an equilibration period, ciliary muscle strips were exposed to selective agonists and antagonists of 5-HT receptors. RESULTS Both selective and nonselective agonists for 5-HT produced concentration-dependent contractions of isolated ciliary muscles with the following rank order of potency: BW723C86>α-methyl-5-HT>MK-212>>8-hydroxy-DPAT>quipazine>R-DOI>>5-HT>>tryptamine. The selective 5-HT2 receptor antagonists, M-100907 (5-HT2A), RS-127445 (5-HT2B), and RS-102221 (5-HT2C), produced noncompetitive inhibition of the contractile effects of selective agonists yielding antagonist potency (pKB) values of 251 ± 27.2 nM (n = 4), 52.5 ± 6.3 nM (n = 4), and 79.4 ± 9.5 nM (n = 4), respectively. CONCLUSION On the basis of the profile of activity of selective agonists and antagonists, we conclude that the 5-HT2B and 5-HT2C receptor subtypes appear to be the predominant serotonin receptors that mediate the contractile action of this amine in bovine isolated ciliary muscles.
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Affiliation(s)
- Sunny E Ohia
- 1 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas
| | - Ya Fatou Njie-Mbye
- 1 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas
| | - Jenaye Robinson
- 1 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas
| | - Leah Mitchell
- 1 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas
| | - Marshalyn Mckoy
- 2 Department of Basic Medical Sciences, Pharmacology Section, University of the West Indies , Kingston, Jamaica
| | - Catherine A Opere
- 3 Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Creighton University , Omaha, Nebraska
| | - Naj A Sharif
- 1 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas.,4 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas
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Shu DY, Lovicu FJ. Myofibroblast transdifferentiation: The dark force in ocular wound healing and fibrosis. Prog Retin Eye Res 2017; 60:44-65. [PMID: 28807717 PMCID: PMC5600870 DOI: 10.1016/j.preteyeres.2017.08.001] [Citation(s) in RCA: 230] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 08/08/2017] [Accepted: 08/09/2017] [Indexed: 02/06/2023]
Abstract
Wound healing is one of the most complex biological processes to occur in life. Repair of tissue following injury involves dynamic interactions between multiple cell types, growth factors, inflammatory mediators and components of the extracellular matrix (ECM). Aberrant and uncontrolled wound healing leads to a non-functional mass of fibrotic tissue. In the eye, fibrotic disease disrupts the normally transparent ocular tissues resulting in irreversible loss of vision. A common feature in fibrotic eye disease is the transdifferentiation of cells into myofibroblasts that can occur through a process known as epithelial-mesenchymal transition (EMT). Myofibroblasts rapidly produce excessive amounts of ECM and exert tractional forces across the ECM, resulting in the distortion of tissue architecture. Transforming growth factor-beta (TGFβ) plays a major role in myofibroblast transdifferentiation and has been implicated in numerous fibrotic eye diseases including corneal opacification, pterygium, anterior subcapsular cataract, posterior capsular opacification, proliferative vitreoretinopathy, fibrovascular membrane formation associated with proliferative diabetic retinopathy, submacular fibrosis, glaucoma and orbital fibrosis. This review serves to introduce the pathological functions of the myofibroblast in fibrotic eye disease. We also highlight recent developments in elucidating the multiple signaling pathways involved in fibrogenesis that may be exploited in the development of novel anti-fibrotic therapies to reduce ocular morbidity due to scarring.
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Affiliation(s)
- Daisy Y Shu
- Discipline of Anatomy and Histology, Bosch Institute, University of Sydney, NSW, Australia; Save Sight Institute, University of Sydney, NSW, Australia
| | - Frank J Lovicu
- Discipline of Anatomy and Histology, Bosch Institute, University of Sydney, NSW, Australia; Save Sight Institute, University of Sydney, NSW, Australia.
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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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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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TGF-β induces phosphorylation of phosphatase and tensin homolog: implications for fibrosis of the trabecular meshwork tissue in glaucoma. Sci Rep 2017; 7:812. [PMID: 28400560 PMCID: PMC5429747 DOI: 10.1038/s41598-017-00845-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 03/16/2017] [Indexed: 01/06/2023] Open
Abstract
Fundamental cell signaling mechanisms that regulate dynamic remodeling of the extracellular matrix (ECM) in mechanically loaded tissues are not yet clearly understood. Trabecular meshwork (TM) tissue in the eye is under constant mechanical stress and continuous remodeling of ECM is crucial to maintain normal aqueous humor drainage and intraocular pressure (IOP). However, excessive ECM remodeling can cause fibrosis of the TM as in primary open-angle glaucoma (POAG) patients, and is characterized by increased resistance to aqueous humor drainage, elevated IOP, optic nerve degeneration and blindness. Increased levels of active transforming growth factor-β2 (TGF-β2) in the aqueous humor is the main cause of fibrosis of TM in POAG patients. Herein, we report a novel finding that, in TM cells, TGF-β-induced increase in collagen expression is associated with phosphorylation of phosphatase and tensin homolog (PTEN) at residues Ser380/Thr382/383. Exogenous overexpression of a mutated form of PTEN with enhanced phosphatase activity prevented the TGF-β-induced collagen expression by TM cells. We propose that rapid alteration of PTEN activity through changes in its phosphorylation status could uniquely regulate the continuous remodeling of ECM in the normal TM. Modulating PTEN activity may have high therapeutic potential to alleviating the fibrosis of TM in POAG patients.
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The role of integrins in glaucoma. Exp Eye Res 2016; 158:124-136. [PMID: 27185161 DOI: 10.1016/j.exer.2016.05.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 05/06/2016] [Accepted: 05/10/2016] [Indexed: 01/04/2023]
Abstract
Integrins are a family of heterodimeric transmembrane receptors that mediate adhesion to the extracellular matrix (ECM). In addition to their role as adhesion receptors, integrins can act as ''bidirectional signal transducers'' that coordinate a large number of cellular activities in response to the extracellular environment and intracellular signaling events. This bidirectional signaling helps maintain tissue homeostasis. Dysregulated bidirectional signaling, however, could trigger the propagation of feedback loops that can lead to the establishment of a disease state such as glaucoma. Here we discuss the role of integrins and bidirectional signaling as they relate to the glaucomatous phenotype with special emphasis on the αvβ3 integrin. We present evidence that this particular integrin may have a significant impact on the pathogenesis of glaucoma.
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Abstract
In order to understand the pathophysiology, select optimal therapeutic options for patients and provide clients with honest expectations for cases of canine glaucoma, clinicians should be familiar with a rational understanding of the functional anatomy of the ocular structures involved in this group of diseases. The topographical extension and the structural and humoral complexity of the regions involved with the production and the outflow of aqueous humor undergo numerous changes with aging and disease. Therefore, the anatomy relative to the fluid dynamics of aqueous has become a pivotal yet flexible concept to interpret the different phenotypes of glaucoma.
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Affiliation(s)
- Stefano Pizzirani
- Ophthalmology, Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, 200 Westboro Road, North Grafton, MA 01536, USA.
| | - Haiyan Gong
- Ophthalmology and Anatomy and Neurobiology, Boston University School of Medicine, 72 East Concord Street, L905, Boston, MA 02118, USA
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Roy Chowdhury U, Hann CR, Stamer WD, Fautsch MP. Aqueous humor outflow: dynamics and disease. Invest Ophthalmol Vis Sci 2015; 56:2993-3003. [PMID: 26024085 DOI: 10.1167/iovs.15-16744] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Affiliation(s)
- Uttio Roy Chowdhury
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - Cheryl R Hann
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Michael P Fautsch
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
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Kuespert S, Junglas B, Braunger BM, Tamm ER, Fuchshofer R. The regulation of connective tissue growth factor expression influences the viability of human trabecular meshwork cells. J Cell Mol Med 2015; 19:1010-20. [PMID: 25704370 PMCID: PMC4420603 DOI: 10.1111/jcmm.12492] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 10/13/2014] [Indexed: 11/30/2022] Open
Abstract
Connective tissue growth factor (CTGF) induces extracellular matrix (ECM) synthesis and contractility in human trabecular meshwork (HTM) cells. Both processes are involved in the pathogenesis of primary open-angle glaucoma. To date, little is known about regulation and function of CTGF expression in the trabecular meshwork (TM). Therefore, we analysed the effects of different aqueous humour proteins and stressors on CTGF expression in HTM cells. HTM cells from three different donors were treated with endothelin-1, insulin-like growth factor (IGF)-1, angiotensin-II, H2O2 and heat shock and were analysed by immunohistochemistry, real-time RT-PCR and Western blotting. Viability after H2O2 treatment was measured in CTGF silenced HTM-N cells and their controls. Latrunculin A reduced expression of CTGF by about 50% compared to untreated HTM cells, whereas endothelin-1, IGF-1, angiotensin-II, heat shock and oxidative stress led to a significant increase. Silencing of CTGF resulted in a delayed expression of αB-crystallin and in reduced cell viability in comparison to the controls after oxidative stress. Conversely, CTGF treatment led to a higher cell viability rate after H2O2 treatment. CTGF expression is induced by factors that have been linked to glaucoma. An increased level of CTGF appears to protect TM cells against damage induced by stress. The beneficial effect of CTGF for viability of TM cells is likely associated with the effects on increased ECM synthesis and higher contractility of the TM, thereby contributing to reduced aqueous humour outflow facility causing increased intraocular pressure.
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Affiliation(s)
- Sabrina Kuespert
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
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Girard MJA, Dupps WJ, Baskaran M, Scarcelli G, Yun SH, Quigley HA, Sigal IA, Strouthidis NG. Translating ocular biomechanics into clinical practice: current state and future prospects. Curr Eye Res 2015; 40:1-18. [PMID: 24832392 PMCID: PMC4233020 DOI: 10.3109/02713683.2014.914543] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Biomechanics is the study of the relationship between forces and function in living organisms and is thought to play a critical role in a significant number of ophthalmic disorders. This is not surprising, as the eye is a pressure vessel that requires a delicate balance of forces to maintain its homeostasis. Over the past few decades, basic science research in ophthalmology mostly confirmed that ocular biomechanics could explain in part the mechanisms involved in almost all major ophthalmic disorders such as optic nerve head neuropathies, angle closure, ametropia, presbyopia, cataract, corneal pathologies, retinal detachment and macular degeneration. Translational biomechanics in ophthalmology, however, is still in its infancy. It is believed that its use could make significant advances in diagnosis and treatment. Several translational biomechanics strategies are already emerging, such as corneal stiffening for the treatment of keratoconus, and more are likely to follow. This review aims to cultivate the idea that biomechanics plays a major role in ophthalmology and that the clinical translation, lead by collaborative teams of clinicians and biomedical engineers, will benefit our patients. Specifically, recent advances and future prospects in corneal, iris, trabecular meshwork, crystalline lens, scleral and lamina cribrosa biomechanics are discussed.
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Affiliation(s)
- Michaël J A Girard
- In Vivo Biomechanics Laboratory, Department of Biomedical Engineering, National University of Singapore , Singapore
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Schwartz D, Samples J, Korosteleva O. Therapeutic ultrasound for glaucoma: clinical use of a low-frequency low-power ultrasound device for lowering intraocular pressure. J Ther Ultrasound 2014; 2:15. [PMID: 25512870 PMCID: PMC4266006 DOI: 10.1186/2050-5736-2-15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Accepted: 08/20/2014] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND This is a first-in-human study to determine the efficacy and tolerability of a new method of treating glaucoma using a low-power, low-frequency, focused therapeutic ultrasound for glaucoma (TUG) device designed to trigger an inflammatory reaction in the anterior chamber angle and trabecular meshwork to enhance outflow. The use of the device is anticipated for mild or moderate open-angle glaucoma as an enhancement to outflow. METHODS In a two-branch clinical trial, a total of 26 primary open-angle glaucoma patients underwent a procedure consisting of the external application of the TUG device. In branch 1, nine of these patients were naïve to pharmaceutical treatment or had been off of medication for over 6 months. In branch 2, 17 patients were treated after a medication washout period. All patients in the study were followed for 12 months. RESULTS In branch 1, there was a decrease in intraocular pressure averaging over 20% lasting at least a year in 74% of the eyes with non-normotensive open-angle glaucoma. In branch 2, an average of two visits while on medication provided the comparison intraocular pressure (IOP) to the effect of the TUG treatment after washout. It was seen that the intraocular pressure over the year post-treatment was equal to or better than the pharmaceutical control in close to 80% of measurements. CONCLUSION A novel device for lowering intraocular pressure is described with a potential for adding to our armamentarium for treating glaucoma. This is a small cohort study which indicates beneficial trends. TRIAL REGISTRATION NUMBER The study was a registered clinical trial, #ISRCTN50904302.
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Affiliation(s)
- Donald Schwartz
- Long Beach Eye Care Associates, 2650 Elm Avenue #108, Long Beach, CA 90806, USA ; USC Eye Institute, Los Angeles, CA, USA ; UC Irvine Gavin Herbert Eye Institute, Irvine, CA, USA
| | | | - Olga Korosteleva
- Department of Mathematics and Statistics, California State University, Long Beach, CA, USA
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Liu C, Feng P, Li X, Song J, Chen W. Expression of MMP-2, MT1-MMP, and TIMP-2 by cultured rabbit corneal fibroblasts under mechanical stretch. Exp Biol Med (Maywood) 2014; 239:907-912. [PMID: 24939826 DOI: 10.1177/1535370214536650] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Refractive surgery not only leads to tissue injury but also evokes mechanical stress increase of the cornea. How the mechanical stress affects the corneal matrix remodeling, specifically, matrix metalloproteinases (MMPs) and their inhibitors (tissue inhibitors of metalloproteinases; TIMPs) is not well understood. In this study, cultured rabbit corneal fibroblasts in vitro were subjected to regimen of 5%, 10%, or 15% equibiaxial stretch at 0.1 Hz for 3 or 24 h. MMP-2 protein level was measured by gelatin zymography and Western blotting. MMP-2, membrane type 1 MMP (MT1-MMP), and TIMP-2 mRNA levels were quantified by real-time quantitative PCR. Extracellular regulated protein kinase (ERK) phosphorylation protein levels were assessed by Western blotting. Our results showed that a 15% stretch resulted in increases in MMP-2 protein, MMP-2 mRNA, and MT1-MMP mRNA levels, but a decrease in TIMP-2 mRNA level. However, a 5% stretch caused decreases in MMP-2 protein and mRNA level, but an increase in TIMP-2 mRNA level, and no change in MT1-MMP mRNA level. A 15% stretch also caused a significant increase in ERK1/2 phosphorylation. Inhibition of the mitogenactivated protein kinase (MEK) pathway with PD98059 attenuated stretch-induced increase in MMP-2 production and ERK activity. These results suggest that small-magnitude stretching may promote corneal matrix synthetic events, whereas large-magnitude stretching promotes corneal matrix degradation by changing the balance between MMPs and TIMPs in corneal fibroblasts. Large-magnitude stretch-induced increase in pro-MMP-2 production was in an ERK-dependent manner.
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Affiliation(s)
- Chengxing Liu
- Institute of Applied Mechanics and Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024, China Shanxi Key lab of Material Strength & Structural Impact, Taiyuan, Shanxi 030024, China School of Basic Medicine, Shanxi Medical University, Taiyuan, Shanxi 030001, China
| | - Pengfei Feng
- Institute of Applied Mechanics and Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024, China Shanxi Key lab of Material Strength & Structural Impact, Taiyuan, Shanxi 030024, China
| | - Xiaona Li
- Institute of Applied Mechanics and Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024, China Shanxi Key lab of Material Strength & Structural Impact, Taiyuan, Shanxi 030024, China
| | - Jie Song
- Institute of Applied Mechanics and Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024, China Shanxi Key lab of Material Strength & Structural Impact, Taiyuan, Shanxi 030024, China
| | - Weiyi Chen
- Institute of Applied Mechanics and Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024, China Shanxi Key lab of Material Strength & Structural Impact, Taiyuan, Shanxi 030024, China
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Dautriche CN, Xie Y, Sharfstein ST. Walking through trabecular meshwork biology: Toward engineering design of outflow physiology. Biotechnol Adv 2014; 32:971-83. [PMID: 24806891 DOI: 10.1016/j.biotechadv.2014.04.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 04/22/2014] [Accepted: 04/29/2014] [Indexed: 01/23/2023]
Abstract
According to the World Health Organization, glaucoma remains the second leading cause of blindness in the world. Glaucoma belongs to a group of optic neuropathies that is characterized by chronic degeneration of the optic nerve along with its supporting glia and vasculature. Despite significant advances in the field, there is no available cure for glaucoma. The trabecular meshwork has been implicated as the primary site for regulation of intraocular pressure, the only known modifiable factor in glaucoma development. In this review, we describe the current models for glaucoma studies, primary culture, anterior eye segments, and animal studies and their limitations. These models, especially anterior eye segments and animal tissues, often require careful interpretation given the inter-species variation and are cumbersome and expensive. The lack of an available in vitro 3D model to study trabecular meshwork cells and detailed mechanisms of their regulation of intraocular pressure has limited progress in the field of glaucoma research. In this paper, we review the current status of knowledge of the trabecular meshwork and how the current advances in tissue engineering techniques might be applied in an effort to engineer a synthetic trabecular meshwork as a 3D in vitro model to further advance glaucoma research. In addition, we describe strategies for selection and design of biomaterials for scaffold fabrication as well as extracellular matrix components to mimic and support the trabecular architecture. We also discuss possible uses for a bioengineered trabecular meshwork for both developing a fundamental understanding of trabecular meshwork biology as well as high-throughput screening of glaucoma drugs.
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Affiliation(s)
- Cula N Dautriche
- SUNY College of Nanoscale Science and Engineering, 257 Fuller Road, Albany, NY 12203, USA
| | - Yubing Xie
- SUNY College of Nanoscale Science and Engineering, 257 Fuller Road, Albany, NY 12203, USA
| | - Susan T Sharfstein
- SUNY College of Nanoscale Science and Engineering, 257 Fuller Road, Albany, NY 12203, USA.
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MTOR-independent induction of autophagy in trabecular meshwork cells subjected to biaxial stretch. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1054-62. [PMID: 24583119 DOI: 10.1016/j.bbamcr.2014.02.010] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 02/04/2014] [Accepted: 02/19/2014] [Indexed: 12/19/2022]
Abstract
The trabecular meshwork (TM) is part of a complex tissue that controls the exit of aqueous humor from the anterior chamber of the eye, and therefore helps maintaining intraocular pressure (IOP). Because of variations in IOP with changing pressure gradients and fluid movement, the TM and its contained cells undergo morphological deformations, resulting in distention and stretching. It is therefore essential for TM cells to continuously detect and respond to these mechanical forces and adapt their physiology to maintain proper cellular function and protect against mechanical injury. Here we demonstrate the activation of autophagy, a pro-survival pathway responsible for the degradation of long-lived proteins and organelles, in TM cells when subjected to biaxial static stretch (20% elongation), as well as in high-pressure perfused eyes (30mmHg). Morphological and biochemical markers for autophagy found in the stretched cells include elevated LC3-II levels, increased autophagic flux, and the presence of autophagic figures in electron micrographs. Furthermore, our results indicate that the stretch-induced autophagy in TM cells occurs in an MTOR- and BAG3-independent manner. We hypothesize that activation of autophagy is part of the physiological response that allows TM cells to cope and adapt to mechanical forces.
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Zheng Y, Currie L, Pollock N, Heath A, Sheridan C, Choudhary A, O'Reilly S, Grierson I. Measurement and computer modeling of temporary arrangements of polygonal actin structures in trabecular meshwork cells which consist of cross-linked actin networks and polygonal actin arrangements. J Ocul Pharmacol Ther 2014; 30:224-36. [PMID: 24438004 DOI: 10.1089/jop.2013.0155] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
PURPOSE In trabecular meshwork (TM) cells, actin geodesic arrangements were measured and then subjected to computational modeling to appreciate the response of different dome shapes to mechanical force. METHODS Polygonal actin arrangements (PAAs) and cross-linked actin networks (CLANs) were induced and imaged by Alexa Flour(®) 488 Phalloidin in bovine TM and human TM cells. Masked images were examined for size, circularity, and spoke and hub dimensions using ImageJ. Finite element modeling was used to create idealized dome structures and "realistic" PAA and CLAN models. The models were subjected to different loads simulating concentrated force and distortion measured. RESULTS We provide evidence that PAAs and CLANs are not identical. Both structures formed flattened domes but PAAs were 6 times larger than CLANs, significantly more circular and had greater height. The dimensions of the triangulations of hubs and spokes were, however, remarkably similar. Hubs were around 2 μm(2) in area, whereas spokes were about 5 μm in length. Our modeling showed that temporary arrangements of polygonal actin structures (TAPAS) were because of their flattened shape, more resistant to shearing than compression when compared with idealized domes. CLANs were marginally more resistant to shearing than PAAs but because of size much more resistant to compression. CONCLUSIONS Evidence is provided that there are 2 types of actin icosahedrons in cultured TM cells we collectively call TAPAS. Modeling suggests that TAPAS have rigidity and are better at dealing with shearing than compression forces. The 2 types of TAPAS, PAAs, and CLANs, have much in common but there are size and mechanical response differences that need to be taken into account in future experimentation.
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Affiliation(s)
- Yalin Zheng
- 1 Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, Faculty of Health and Life Sciences, University of Liverpool , Liverpool, United Kingdom
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Sharif NA, May JA. Potential for serotonergic agents to treat elevated intraocular pressure and glaucoma: focus on 5-HT2receptor agonists. EXPERT REVIEW OF OPHTHALMOLOGY 2014. [DOI: 10.1586/eop.10.69] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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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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Jordan JF, Wecker T, van Oterendorp C, Anton A, Reinhard T, Boehringer D, Neuburger M. Trabectome surgery for primary and secondary open angle glaucomas. Graefes Arch Clin Exp Ophthalmol 2013; 251:2753-60. [PMID: 24158374 PMCID: PMC3889259 DOI: 10.1007/s00417-013-2500-7] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 08/20/2013] [Accepted: 10/08/2013] [Indexed: 02/04/2023] Open
Abstract
Purpose In most forms of open angle glaucoma, the trabecular meshwork is the main barrier for aqueous humor outflow, causing elevated intraocular pressure (IOP). The Trabectome is a minimal invasive device for the surgical treatment of open angle glaucoma, particularly eliminating the juxtacanalicular meshwork. This study was conducted to compare the effectiveness and complication profile among different glaucoma subgroups. Methods Single center prospective observational study. There were 557 consecutive eyes of 487 patients included in this study. Trabectome surgery was performed either alone or in combination with cataract surgery. Intraoperative and postoperative complications were documented systematically. Main outcome measures were IOP reduction over time and the preoperative and postoperative number of IOP-lowering medications. Due to subgroup sizes, only data from eyes with primary open angle glaucoma and pseudoexfoliation glaucoma were processed for statistical analysis. Results For the 261 eyes classified as primary open angle glaucoma, preoperative IOP was 24 ± 5.5 mmHg (mean ± SD) under 2.1 ± 1.3 IOP-lowering medications. After a mean follow-up of 204 ± 238 days, IOP was reduced to 18 ± 6.1 mmHg, and medication was reduced to 1.2 ± 1.1. For the 173 eyes classified as pseudoexfoliation glaucoma, after a mean follow-up of 200 ± 278 days, IOP was reduced from 25 ± 5.9 mmHg to 18 ± 8.2 mmHg, and medication was reduced from 2.0 ± 1.2 to 1.1 ± 1.1. A Cox proportional hazards model hinted forward superiority of the combined surgery cases (Trabectome + Phaco + intraocular lens) in comparison to Trabectome surgery only in phakic or pseudophakic eyes. No serious complications were observed. Conclusions Minimal invasive glaucoma surgery with the Trabectome seems to be safe and effective. The subgroup analysis of different kinds of open angle glaucomas presented in this study may help in first-line patient selection. The lack of ocular surface alterations makes it a valuable addition to glaucoma surgery.
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Affiliation(s)
- Jens F Jordan
- University Eye Hospital, Killianstr. 5, 79106, Freiburg, Germany,
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