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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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Nian Q, Chi J, Xiao Q, Wei C, Costeas P, Yang Z, Liu L, Wang L. SPARC ectopic overexpression inhibits growth and promotes programmed cell death in acute myeloid leukemia transformed from myelodysplastic syndrome cells, alone and in combination with Ara-C treatment. Oncol Rep 2015; 34:1406-14. [PMID: 26165695 DOI: 10.3892/or.2015.4114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 05/12/2015] [Indexed: 11/05/2022] Open
Abstract
Secreted protein acidic and rich in cysteine (SPARC) has a complex and pleiotropic biological role in cell life during disease. The role of SPARC in myelodysplastic syndrome (MDS) is not yet fully understood. In the present study, we investigated the role of SPARC protein overproduction in the proliferation and apoptosis of SKM-1 cells, an acute myeloid leukemia cell line transformed from MDS. SKM-1 cells were infected with the pGC-GV-SPARC vector. The cells were then assessed for proliferation and cell death following treatment with low-dose cytosine arabinoside (Ara‑C). The microarray analysis results revealed that samples from SPARC‑overexpressed cells compared to SPARC protein, in SKM-1 cells led to proliferation inhibition and promoted programmed cell death and these effects were greater when treated with Ara-C. The mRNA and protein expression levels of SPARC were detected by SPARC overexpression in cells treated with Ara-C resulting in a significant upregulation of the mixed lineage kinase domain-like (MLKL) gene expression and five other genes. The results showed that the necrotic signaling pathway may play a role when the two conditions were combined via the upregulation of the MLKL protein. MLKL upregulation in SPARC overexpressed cells treated with Ara-C, indicates necrosis as a possible cell death process for the SKM-1 cells under these stringent conditions.
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Affiliation(s)
- Qing Nian
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Jianxiang Chi
- The Center for the Study of Haematological Malignancies, Nicosia 2032, Cyprus
| | - Qing Xiao
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Chunmei Wei
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Paul Costeas
- The Center for the Study of Haematological Malignancies, Nicosia 2032, Cyprus
| | - Zesong Yang
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Lin Liu
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Li Wang
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
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Scavelli K, Chatterjee A, Rhee DJ. Secreted Protein Acidic and Rich in Cysteine in Ocular Tissue. J Ocul Pharmacol Ther 2015; 31:396-405. [PMID: 26167673 DOI: 10.1089/jop.2015.0057] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Secreted protein acidic and rich in cysteine (SPARC), also known as osteonectin or BM-40, is the prototypical matricellular protein. Matricellular proteins are nonstructural secreted proteins that provide an integration between cells and their surrounding extracellular matrix (ECM). Regulation of the ECM is important in maintaining the physiologic function of tissues. Elevated levels of SPARC have been identified in a variety of diseases involving pathologic tissue remodeling, such as hepatic fibrosis, systemic sclerosis, and certain carcinomas. Within the eye, SPARC has been identified in the trabecular meshwork, lens, and retina. Studies have begun to show the role of SPARC in these tissues and its possible role, specifically in primary open-angle glaucoma, cataracts, and proliferative vitreoretinopathy. SPARC may, therefore, be a therapeutic target in the treatment of certain ocular diseases. Further investigation into the mechanism of action of SPARC will be necessary in the development of SPARC-targeted therapy.
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Affiliation(s)
- Kurt Scavelli
- Department of Ophthalmology and Visual Sciences, University Hospitals Eye Institute, Case Western Reserve University School of Medicine , Cleveland, Ohio
| | - Ayan Chatterjee
- Department of Ophthalmology and Visual Sciences, University Hospitals Eye Institute, Case Western Reserve University School of Medicine , Cleveland, Ohio
| | - Douglas J Rhee
- Department of Ophthalmology and Visual Sciences, University Hospitals Eye Institute, Case Western Reserve University School of Medicine , Cleveland, Ohio
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Morgan JT, Raghunathan VK, Chang YR, Murphy CJ, Russell P. The intrinsic stiffness of human trabecular meshwork cells increases with senescence. Oncotarget 2015; 6:15362-74. [PMID: 25915531 PMCID: PMC4558157 DOI: 10.18632/oncotarget.3798] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 03/20/2015] [Indexed: 12/26/2022] Open
Abstract
Dysfunction of the human trabecular meshwork (HTM) plays a central role in the age-associated disease glaucoma, a leading cause of irreversible blindness. The etiology remains poorly understood but cellular senescence, increased stiffness of the tissue, and the expression of Wnt antagonists such as secreted frizzled related protein-1 (SFRP1) have been implicated. However, it is not known if senescence is causally linked to either stiffness or SFRP1 expression. In this study, we utilized in vitro HTM senescence to determine the effect on cellular stiffening and SFRP1 expression. Stiffness of cultured cells was measured using atomic force microscopy and the morphology of the cytoskeleton was determined using immunofluorescent analysis. SFRP1 expression was measured using qPCR and immunofluorescent analysis. Senescent cell stiffness increased 1.88±0.14 or 2.57±0.14 fold in the presence or absence of serum, respectively. This was accompanied by increased vimentin expression, stress fiber formation, and SFRP1 expression. In aggregate, these data demonstrate that senescence may be a causal factor in HTM stiffening and elevated SFRP1 expression, and contribute towards disease progression. These findings provide insight into the etiology of glaucoma and, more broadly, suggest a causal link between senescence and altered tissue biomechanics in aging-associated diseases.
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Affiliation(s)
- Joshua T. Morgan
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - Vijay Krishna Raghunathan
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - Yow-Ren Chang
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - Christopher J. Murphy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA
- Department of Ophthalmology &; Vision Science, School of Medicine, University of California, Davis, CA, USA
| | - Paul Russell
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA
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Vranka JA, Kelley MJ, Acott TS, Keller KE. Extracellular matrix in the trabecular meshwork: intraocular pressure regulation and dysregulation in glaucoma. Exp Eye Res 2015; 133:112-25. [PMID: 25819459 DOI: 10.1016/j.exer.2014.07.014] [Citation(s) in RCA: 251] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 07/14/2014] [Accepted: 07/16/2014] [Indexed: 12/30/2022]
Abstract
The trabecular meshwork (TM) is located in the anterior segment of the eye and is responsible for regulating the outflow of aqueous humor. Increased resistance to aqueous outflow causes intraocular pressure to increase, which is the primary risk factor for glaucoma. TM cells reside on a series of fenestrated beams and sheets through which the aqueous humor flows to exit the anterior chamber via Schlemm's canal. The outer trabecular cells are phagocytic and are thought to function as a pre-filter. However, most of the outflow resistance is thought to be from the extracellular matrix (ECM) of the juxtacanalicular region, the deepest portion of the TM, and from the inner wall basement membrane of Schlemm's canal. It is becoming increasingly evident that the extracellular milieu is important in maintaining the integrity of the TM. In glaucoma, not only have ultrastructural changes been observed in the ECM of the TM, and a significant number of mutations in ECM genes been noted, but the stiffness of glaucomatous TM appears to be greater than that of normal tissue. Additionally, TGFβ2 has been found to be elevated in the aqueous humor of glaucoma patients and is assumed to be involved in ECM changes deep with the juxtacanalicular region of the TM. This review summarizes the current literature on trabecular ECM as well as the development and function of the TM. Animal models and organ culture models targeting specific ECM molecules to investigate the mechanisms of glaucoma are described. Finally, the growing number of mutations that have been identified in ECM genes and genes that modulate ECM in humans with glaucoma are documented.
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Affiliation(s)
- Janice A Vranka
- Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Mary J Kelley
- Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Ted S Acott
- Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Kate E Keller
- Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA.
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Vranka JA, Bradley JM, Yang YF, Keller KE, Acott TS. Mapping molecular differences and extracellular matrix gene expression in segmental outflow pathways of the human ocular trabecular meshwork. PLoS One 2015; 10:e0122483. [PMID: 25826404 PMCID: PMC4380331 DOI: 10.1371/journal.pone.0122483] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 02/22/2015] [Indexed: 01/09/2023] Open
Abstract
Elevated intraocular pressure (IOP) is the primary risk factor for glaucoma, and lowering IOP remains the only effective treatment for glaucoma. The trabecular meshwork (TM) in the anterior chamber of the eye regulates IOP by generating resistance to aqueous humor outflow. Aqueous humor outflow is segmental, but molecular differences between high and low outflow regions of the TM are poorly understood. In this study, flow regions of the TM were characterized using fluorescent tracers and PCR arrays. Anterior segments from human donor eyes were perfused at physiological pressure in an ex vivo organ culture system. Fluorescently-labeled microspheres of various sizes were perfused into anterior segments to label flow regions. Actively perfused microspheres were segmentally distributed, whereas microspheres soaked passively into anterior segments uniformly labeled the TM and surrounding tissues with no apparent segmentation. Cell-tracker quantum dots (20 nm) were localized to the outer uveal and corneoscleral TM, whereas larger, modified microspheres (200 nm) localized throughout the TM layers and Schlemm’s canal. Distribution of fluorescent tracers demonstrated a variable labeling pattern on both a macro- and micro-scale. Quantitative PCR arrays allowed identification of a variety of extracellular matrix genes differentially expressed in high and low flow regions of the TM. Several collagen genes (COL16A1, COL4A2, COL6A1 and 2) and MMPs (1, 2, 3) were enriched in high, whereas COL15A1, and MMP16 were enriched in low flow regions. Matrix metalloproteinase activity was similar in high and low regions using a quantitative FRET peptide assay, whereas protein levels in tissues showed modest regional differences. These gene and protein differences across regions of the TM provide further evidence for a molecular basis of segmental flow routes within the aqueous outflow pathway. New insight into the molecular mechanisms of segmental aqueous outflow may aid in the design and delivery of improved treatments for glaucoma patients.
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Affiliation(s)
- Janice A. Vranka
- Casey Eye Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, Oregon, United States of America
- * E-mail:
| | - John M. Bradley
- Casey Eye Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, Oregon, United States of America
| | - Yong-Feng Yang
- Casey Eye Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, Oregon, United States of America
| | - Kate E. Keller
- Casey Eye Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, Oregon, United States of America
| | - Ted S. Acott
- Casey Eye Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, Oregon, United States of America
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Swaminathan SS, Oh DJ, Kang MH, Rhee DJ. Aqueous outflow: segmental and distal flow. J Cataract Refract Surg 2015; 40:1263-72. [PMID: 25088623 DOI: 10.1016/j.jcrs.2014.06.020] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 06/13/2014] [Accepted: 06/14/2014] [Indexed: 12/29/2022]
Abstract
UNLABELLED The elevated intraocular pressure (IOP) of primary open-angle glaucoma is caused by impaired outflow of aqueous humor through the trabecular meshwork. Within the juxtacanalicular region, alterations of both extracellular matrix homeostasis and the cellular tone of trabecular meshwork endothelial and the inner wall of Schlemm canal cells affect outflow. Newer pharmacologic agents that target trabecular meshwork and Schlemm canal cell cytoskeleton lower IOP. Aqueous drainage occurs nonhomogenously with greater flow going through certain portions of the TM and less going through other portions-a concept known as segmental flow, which is theoretically the result of outflow being dependent on the presence of discrete pores within Schlemm canal. The limited long-term success of trabecular meshwork bypass surgeries implicates the potential impact of resistance in Schlemm canal itself and collector channels. Additionally, others have observed that outflow occurs preferentially near collector channels. These distal structures may be more important to aqueous outflow than previously believed. FINANCIAL DISCLOSURE Dr. Rhee is a consultant to Aerie Pharmaceuticals, Alcon Laboratories, Inc., Allegan, Inc., Aquesys, Inc., Glaukos Corp., Ivantis, Inc., Johnson & Johnson, Merck Sharp & Dohme Corp. and Santen, Inc., and has received research funding from Alcon Laboratories, Inc., Merck Sharp & Dohme Corp., and Ivantis, Inc. No other author has a financial or proprietary interest in any material or method mentioned.
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Affiliation(s)
- Swarup S Swaminathan
- From Harvard-MIT Division of Health Sciences and Technology (Swaminathan), Harvard Medical School, Boston, Massachusetts, and the Department of Ophthalmology & Visual Sciences (Oh, Kang, Rhee), Case Western Reserve University, Cleveland, Ohio, USA
| | - Dong-Jin Oh
- From Harvard-MIT Division of Health Sciences and Technology (Swaminathan), Harvard Medical School, Boston, Massachusetts, and the Department of Ophthalmology & Visual Sciences (Oh, Kang, Rhee), Case Western Reserve University, Cleveland, Ohio, USA
| | - Min Hyung Kang
- From Harvard-MIT Division of Health Sciences and Technology (Swaminathan), Harvard Medical School, Boston, Massachusetts, and the Department of Ophthalmology & Visual Sciences (Oh, Kang, Rhee), Case Western Reserve University, Cleveland, Ohio, USA
| | - Douglas J Rhee
- From Harvard-MIT Division of Health Sciences and Technology (Swaminathan), Harvard Medical School, Boston, Massachusetts, and the Department of Ophthalmology & Visual Sciences (Oh, Kang, Rhee), Case Western Reserve University, Cleveland, Ohio, USA.
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58
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Stamer WD, Braakman ST, Zhou EH, Ethier CR, Fredberg JJ, Overby DR, Johnson M. Biomechanics of Schlemm's canal endothelium and intraocular pressure reduction. Prog Retin Eye Res 2015; 44:86-98. [PMID: 25223880 PMCID: PMC4268318 DOI: 10.1016/j.preteyeres.2014.08.002] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/25/2014] [Accepted: 08/26/2014] [Indexed: 12/29/2022]
Abstract
Ocular hypertension in glaucoma develops due to age-related cellular dysfunction in the conventional outflow tract, resulting in increased resistance to aqueous humor outflow. Two cell types, trabecular meshwork (TM) and Schlemm's canal (SC) endothelia, interact in the juxtacanalicular tissue (JCT) region of the conventional outflow tract to regulate outflow resistance. Unlike endothelial cells lining the systemic vasculature, endothelial cells lining the inner wall of SC support a transcellular pressure gradient in the basal to apical direction, thus acting to push the cells off their basal lamina. The resulting biomechanical strain in SC cells is quite large and is likely to be an important determinant of endothelial barrier function, outflow resistance and intraocular pressure. This review summarizes recent work demonstrating how biomechanical properties of SC cells impact glaucoma. SC cells are highly contractile, and such contraction greatly increases cell stiffness. Elevated cell stiffness in glaucoma may reduce the strain experienced by SC cells, decrease the propensity of SC cells to form pores, and thus impair the egress of aqueous humor from the eye. Furthermore, SC cells are sensitive to the stiffness of their local mechanical microenvironment, altering their own cell stiffness and modulating gene expression in response. Significantly, glaucomatous SC cells appear to be hyper-responsive to substrate stiffness. Thus, evidence suggests that targeting the material properties of SC cells will have therapeutic benefits for lowering intraocular pressure in glaucoma.
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Affiliation(s)
- W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA; Department of Biomedical Engineering, Duke University, Durham, NC, 27710, USA.
| | - Sietse T Braakman
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
| | - Enhua H Zhou
- Department of Ophthalmology, Novartis Institutes of BioMedical Research, Cambridge, MA 02139, USA
| | - C Ross Ethier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; Department of Biomedical Engineering, Emory University, Atlanta, GA 30322, USA; Department of Ophthalmology, Emory University, Atlanta, GA 30322, USA
| | - Jeffrey J Fredberg
- Program in Molecular and Integrative Physiological Sciences, Harvard School of Public Health, Boston, MA 02115, USA; Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115, USA
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
| | - Mark Johnson
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, US; Department of Mechanical Engineering, Northwestern University, Evanston, IL, USA; Department of Ophthalmology Engineering, Northwestern University, Chicago, IL, USA
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Villarreal G, Chatterjee A, Oh SS, Oh DJ, Kang MH, Rhee DJ. Canonical wnt signaling regulates extracellular matrix expression in the trabecular meshwork. Invest Ophthalmol Vis Sci 2014; 55:7433-40. [PMID: 25352117 DOI: 10.1167/iovs.13-12652] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PURPOSE Canonical Wnt signaling has emerged as a critical regulator of aqueous outflow facility and intraocular pressure (IOP). In this study, we examine the role of canonical Wnt signaling on extracellular matrix (ECM) expression in the trabecular meshwork (TM) and explore the molecular mechanisms involved. METHODS β-catenin localization in human TM tissue was examined using immunofluorescent staining. Primary human TM cells were incubated with lithium chloride (LiCl) and the effect on active β-catenin expression was assessed by immunoblot. Adenovirus expressing a dominant-negative TCF4 mutant that lacks a β-catenin binding domain was used. Changes in the levels of the microRNA-29 (miR-29) family and ECM proteins were determined by real-time quantitative PCR and immunoblot analysis, respectively. RESULTS β-catenin was expressed throughout the TM, with localization primarily to the plasma membrane. Incubation of TM cells with lithium chloride increased the expression of active β-catenin. Lithium chloride treatment upregulated miR-29b expression, and suppressed the levels of various ECM proteins under both basal and TGF-β2 stimulatory conditions. Infection of TM cells with a dominant-negative TCF4 mutant induced ECM levels without a significant change in the expression of the miR-29 family. CONCLUSIONS Collectively, our data identify the canonical Wnt signaling pathway as an important modulator of ECM expression in the TM and provide a mechanistic framework for its regulation of outflow facility and IOP.
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Affiliation(s)
- Guadalupe Villarreal
- Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States
| | - Ayan Chatterjee
- Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States
| | - Sarah S Oh
- Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States
| | - Dong-Jin Oh
- Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States
| | - Min Hyung Kang
- Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States
| | - Douglas J Rhee
- Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States
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Yun H, Lathrop KL, Yang E, Sun M, Kagemann L, Fu V, Stolz DB, Schuman JS, Du Y. A laser-induced mouse model with long-term intraocular pressure elevation. PLoS One 2014; 9:e107446. [PMID: 25216052 PMCID: PMC4162591 DOI: 10.1371/journal.pone.0107446] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 08/10/2014] [Indexed: 12/13/2022] Open
Abstract
Purpose To develop and characterize a mouse model with intraocular pressure (IOP) elevation after laser photocoagulation on the trabecular meshwork (TM), which may serve as a model to investigate the potential of stem cell-based therapies for glaucoma. Methods IOP was measured in 281 adult C57BL/6 mice to determine normal IOP range. IOP elevation was induced unilaterally in 50 adult mice, by targeting the TM through the limbus with a 532-nm diode laser. IOP was measured up to 24 weeks post-treatment. The optic nerve damage was detected by electroretinography and assessed by semiautomatic counting of optic nerve axons. Effects of laser treatment on the TM were evaluated by histology, immunofluorescence staining, optical coherence tomography (OCT) and transmission electron microscopy (TEM). Results The average IOP of C57BL/6 mice was 14.5±2.6 mmHg (Mean ±SD). After laser treatment, IOP averaged above 20 mmHg throughout the follow-up period of 24 weeks. At 24 weeks, 57% of treated eyes had elevated IOP with the mean IOP of 22.5±2.5 mmHg (Mean ±SED). The difference of average axon count (59.0%) between laser treated and untreated eyes was statistically significant. Photopic negative response (PhNR) by electroretinography was significantly decreased. CD45+ inflammatory cells invaded the TM within 1 week. The expression of SPARC was increased in the TM from 1 to 12 weeks. Histology showed the anterior chamber angle open after laser treatment. OCT indicated that most of the eyes with laser treatment had no synechia in the anterior chamber angles. TEM demonstrated disorganized and compacted extracellular matrix in the TM. Conclusions An experimental murine ocular hypertension model with an open angle and optic nerve axon loss was produced with laser photocoagulation, which could be used to investigate stem cell-based therapies for restoration of the outflow pathway integrity for ocular hypertension or glaucoma.
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Affiliation(s)
- Hongmin Yun
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Kira L. Lathrop
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Enzhi Yang
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Ming Sun
- Department of Cell Biology, Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Larry Kagemann
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Valeria Fu
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Donna B. Stolz
- Department of Cell Biology, Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Joel S. Schuman
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Yiqin Du
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Developmental Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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61
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Swaminathan SS, Oh DJ, Kang MH, Shepard AR, Pang IH, Rhee DJ. TGF-β2-mediated ocular hypertension is attenuated in SPARC-null mice. Invest Ophthalmol Vis Sci 2014; 55:4084-97. [PMID: 24906856 DOI: 10.1167/iovs.13-12463] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
PURPOSE Transforming growth factor-β2 (TGF-β2) has been implicated in the pathogenesis of primary open-angle glaucoma through extracellular matrix (ECM) alteration among various mechanisms. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein that regulates ECM within the trabecular meshwork (TM), and is highly upregulated by TGF-β2. We hypothesized that, in vivo, SPARC is a critical regulatory node in TGF-β2-mediated ocular hypertension. METHODS Empty (Ad.empty) or TGF-β2-containing adenovirus (Ad.TGF-β2) was injected intravitreally into C57BL6-SV129 WT and SPARC-null mice. An initial study was performed to identify a stable period for IOP measurement under isoflurane. The IOP was measured before injection and every other day for two weeks using rebound tonometry. Additional mice were euthanized at peak IOP for immunohistochemistry. RESULTS The IOP was stable under isoflurane during minutes 5 to 8. The IOP was significantly elevated in Ad.TGF-β2-injected (n = 8) versus Ad.empty-injected WT (n = 8) mice and contralateral uninjected eyes during days 4 to 11 (P < 0.03). The IOPs were not significantly elevated in Ad.TGF-β2-injected versus Ad.empty-injected SPARC-null mice. However, on day 8, the IOP of Ad.TGF-β2-injected SPARC-null eyes was elevated compared to that of contralateral uninjected eyes (P = 0.0385). Immunohistochemistry demonstrated that TGF-β2 stimulated increases in collagen IV, fibronectin, plasminogen activator inhibitor-1 (PAI-1), connective tissue growth factor (CTGF), and SPARC in WT mice, but only PAI-1 and CTGF in SPARC-null mice (P < 0.05). CONCLUSIONS SPARC is essential to the regulation of TGF-β2-mediated ocular hypertension. Deletion of SPARC significantly attenuates the effects of TGF-β2 by restricting collagen IV and fibronectin expression. These data provide further evidence that SPARC may have an important role in IOP regulation and possibly glaucoma pathogenesis.
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Affiliation(s)
- Swarup S Swaminathan
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States
| | - Dong-Jin Oh
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States
| | - Min Hyung Kang
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States
| | - Allan R Shepard
- Ophthalmology Research/Glaucoma Research, Novartis Institutes for Biomedical Research, Fort Worth, Texas, United States
| | - Iok-Hou Pang
- Department of Pharmaceutical Sciences and North Texas Eye Research Institute, University of North Texas Health Sciences Center, Fort Worth, Texas, United States
| | - Douglas J Rhee
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States
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Chatterjee A, Villarreal G, Rhee DJ. Matricellular proteins in the trabecular meshwork: review and update. J Ocul Pharmacol Ther 2014; 30:447-63. [PMID: 24901502 DOI: 10.1089/jop.2014.0013] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Abstract Primary open-angle glaucoma (POAG) is a leading cause of blindness worldwide, and intraocular pressure (IOP) is an important modifiable risk factor. IOP is a function of aqueous humor production and aqueous humor outflow, and it is thought that prolonged IOP elevation leads to optic nerve damage over time. Within the trabecular meshwork (TM), the eye's primary drainage system for aqueous humor, matricellular proteins generally allow cells to modulate their attachments with and alter the characteristics of their surrounding extracellular matrix (ECM). It is now well established that ECM turnover in the TM affects outflow facility, and matricellular proteins are emerging as significant players in IOP regulation. The formalized study of matricellular proteins in TM has gained increased attention. Secreted protein acidic and rich in cysteine (SPARC), myocilin, connective tissue growth factor (CTGF), and thrombospondin-1 and -2 (TSP-1 and -2) have been localized to the TM, and a growing body of evidence suggests that these matricellular proteins play an important role in IOP regulation and possibly the pathophysiology of POAG. As evidence continues to emerge, these proteins are now seen as potential therapeutic targets. Further study is warranted to assess their utility in treating glaucoma in humans.
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Affiliation(s)
- Ayan Chatterjee
- Department of Ophthalmology and Visual Sciences, University Hospitals Eye Institute, Case Western Reserve University School of Medicine , Cleveland, Ohio
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Chatterjee A, Villarreal G, Oh DJ, Kang MH, Rhee DJ. AMP-activated protein kinase regulates intraocular pressure, extracellular matrix, and cytoskeleton in trabecular meshwork. Invest Ophthalmol Vis Sci 2014; 55:3127-39. [PMID: 24713487 DOI: 10.1167/iovs.13-12755] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
PURPOSE In this study, we investigate how adenosine monophosphate-activated protein kinase (AMPK) affects extracellular matrix (ECM) and cellular tone in the trabecular meshwork (TM), and examine how deletion of its catalytic α2 subunit affects IOP and aqueous humor clearance in mice. METHODS Human TM tissue was examined for expression of AMPKα1 and AMPKα2, genomically distinct isoforms of the AMPK catalytic subunit. Primary cultured human TM cells were treated for 24 hours with the AMPK activator 5-amino-1-β-Dffff-ribofuranosyl-imidazole-4-carboxamide (AICAR), under basal or TGF-β2 stimulatory conditions. Conditioned media (CM) was probed for secreted protein acidic and rich in cysteine (SPARC), thrombospondin-1 (TSP-1), and ECM proteins, and cells were stained for F-actin. Cells underwent adenoviral infection with a dominant negative AMPKα subunit (ad.DN.AMPKα) and were similarly analyzed. Intraocular pressure, central corneal thickness (CCT), and aqueous clearance were measured in AMPKα2-null and wild-type (WT) mice. RESULTS Both AMPKα1 and AMPKα2 are expressed in TM. AICAR activated AMPKα and suppressed the expression of various ECM proteins under basal and TGF-β2 stimulatory conditions. AICAR decreased F-actin staining and increased the phospho-total RhoA ratio (Ser188). Transforming growth factor-β2 transiently dephosphorylated AMPKα. Infection with ad.DN.AMPKα upregulated various ECM proteins, decreased the phospho-total RhoA ratio, and increased F-actin staining. AMPKα2-null mice exhibited 6% higher IOP and decreased aqueous clearance compared with WT mice, without significant differences in CCT or angle morphology. CONCLUSIONS Collectively, our data identify AMPK as a critical regulator of ECM homeostasis and cytoskeletal arrangement in the TM. Mice that are AMPKα2-null exhibit higher IOPs and decreased aqueous clearance than their WT counterparts.
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Affiliation(s)
- Ayan Chatterjee
- Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States
| | - Guadalupe Villarreal
- Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States
| | - Dong-Jin Oh
- Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States
| | - Min Hyung Kang
- Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States
| | - Douglas J Rhee
- Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States
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Villarreal G, Chatterjee A, Oh SS, Oh DJ, Rhee DJ. Pharmacological regulation of SPARC by lovastatin in human trabecular meshwork cells. Invest Ophthalmol Vis Sci 2014; 55:1657-65. [PMID: 24474275 DOI: 10.1167/iovs.13-12712] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
PURPOSE Statins have been shown to increase aqueous outflow facility. The matricellular protein SPARC (secreted protein acidic and rich in cysteine) is a critical mediator of aqueous outflow and intraocular pressure (IOP). Here, we examine the effects of lovastatin on SPARC expression in trabecular meshwork (TM) cells, exploring the molecular mechanisms involved. METHODS Primary cultured human TM cells were incubated for 24, 48, and 72 hours with 10 μM lovastatin. In separate cultures, media was supplemented with either farnesyl pyrophosphate (FPP) or geranylgeranyl pyrophosphate (GGPP) for the duration of the 72-hour time point experiment. Trabecular meshwork cells were also pretreated for 24 hours with lovastatin followed by 24-hour stimulation with 3 ng/mL TGF-β2. Cell lysates and media were harvested and relative mRNA and protein level changes were determined. Krüppel-like factor 4 (KLF4) localization in normal human anterior segments was examined by immunofluorescence. Adenovirus expressing human KLF4 was used and relative changes in SPARC mRNA and protein levels were assessed. RESULTS Incubating TM cells with lovastatin suppressed SPARC mRNA and protein levels. This effect was reversed upon media supplementation with GGPP but not FPP. Pretreating cells with lovastatin inhibited TGF-β2 induction of SPARC. The KLF4 transcription factor was expressed throughout the TM and the inner and outer walls of Schlemm's canal. Lovastatin treatment upregulated KLF4 mRNA and protein levels. Overexpression of KLF4 downregulated SPARC expression. CONCLUSIONS Collectively, our data identify lovastatin as an important pharmacological suppressor of SPARC expression in TM cells, and provide further insight into the molecular mechanisms mediating statin enhancement of aqueous outflow facility.
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Affiliation(s)
- Guadalupe Villarreal
- Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts
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Nian Q, Xiao Q, Wang L, Luo J, Chen LP, Yang ZS, Liu L. SPARC silencing inhibits the growth of acute myeloid leukemia transformed from myelodysplastic syndrome via induction of cell cycle arrest and apoptosis. Int J Mol Med 2014; 33:856-62. [PMID: 24535175 PMCID: PMC3976133 DOI: 10.3892/ijmm.2014.1648] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 01/29/2014] [Indexed: 12/23/2022] Open
Abstract
Secreted protein acidic and rich in cysteine (SPARC) plays key roles in erythropoiesis; haploinsufficiency of SPARC is implicated in the progression of the 5q- syndrome. However, the role of SPARC in other subtypes of myelodysplastic syndrome (MDS) is not fully understood, particularly in the del(5q) type with a complex karyotype, which has a high risk to transform into acute myeloid leukemia (AML). In the present study, we investigated the role of SPARC in the proliferation and apoptosis of SKM-1 cells, an acute myeloid leukemia cell line transformed from an MDS cell line. SKM-1 cells were infected with SPARC-RNAi-LV or NC-GFP-LV lentivirus. Apoptosis and cell cycle profiling were assessed by flow cytometry, and cell proliferation was evaluated by MTS assay. The mRNA and protein expression levels of SPARC, p53, caspase-3, caspase-9 and Fas were detected by RT-PCR, real-time PCR and western blot assay. The SPARC shRNA constructed by us led to a significant reduction in SPARC expression in SKM-1 cells. SPARC knockdown inhibited the proliferation of SKM-1 cells by inducing cell cycle arrest at the G1/G0 phase and apoptosis. SPARC knockdown elevated the expression of p53, caspase-9, caspase-3 and Fas at both the mRNA and protein levels. SPARC silencing inhibited the growth of AML transformed from MDS by activating p53-induced apoptosis and cell cycle arrest. These data indicate that SPARC acts as an oncogene in transformed MDS/AML and is a potential therapeutic target in MDS/AML.
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Affiliation(s)
- Qing Nian
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Qing Xiao
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Li Wang
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Jing Luo
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Li-Ping Chen
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Ze-Song Yang
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Lin Liu
- Department of Hematology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
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66
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Gong H, Yang CYC. Morphological and hydrodynamic correlations with increasing outflow facility by rho-kinase inhibitor Y-27632. J Ocul Pharmacol Ther 2014; 30:143-53. [PMID: 24460021 DOI: 10.1089/jop.2013.0192] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Abstract Rho-kinase inhibitors affect actomyosin cytoskeletal networks and have been shown to significantly increase outflow facility and lower intraocular pressure in various animal models and human eyes. This article summarizes common morphological changes in the trabecular meshwork induced by Rho-kinase inhibitors and specifically compares the morphological and hydrodynamic correlations with increased outflow facility by Rho-kinase inhibitor, Y-27632, in bovine, monkey, and human eyes under similar experimental conditions. Interspecies comparison has shown that morphological changes in the juxtacanalicular connective tissue (JCT) of these 3 species were different. However, these different morphological changes in the JCT, no matter if it's separation between the JCT and inner wall in bovine eyes, or separation between the JCT cells or between the JCT cells and their matrix in monkey eyes, or even no separation between the inner wall and the JCT but a more subtle expansion of the JCT in human eyes, appear to correlate with the increased percent change of outflow facility. More importantly, these different morphological changes all resulted in an increase in effective filtration area, which was positively correlated with increased outflow facility in all 3 species. These results suggest a link among changes in outflow facility, tissue architecture, and aqueous outflow pattern. Y-27632 increases outflow facility by redistributing aqueous outflow through a looser and larger area in the JCT.
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Affiliation(s)
- Haiyan Gong
- 1 Department of Ophthalmology, Boston University School of Medicine , Boston, Massachusetts
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Chang JYH, Folz SJ, Laryea SN, Overby DR. Multi-scale analysis of segmental outflow patterns in human trabecular meshwork with changing intraocular pressure. J Ocul Pharmacol Ther 2014; 30:213-23. [PMID: 24456518 DOI: 10.1089/jop.2013.0182] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
PURPOSE Aqueous humor filtration in the trabecular meshwork is believed to be non-uniform or "segmental" such that only a fraction of trabecular meshwork is filtration-active at any given instant. The goal was to quantify the filtration-active fraction of human trabecular meshwork and to determine how filtration patterns change with outflow facility and intraocular pressure (IOP). METHODS Six pair of enucleated human eyes were perfused with fluorescent tracer microspheres (0.2 μm) at 7 or 30 mmHg. Tracer patterns were imaged over the "macro-scale" (0.1-10 mm) using epifluorescence microscopy and "micro-scale" (10-100 μm) using confocal microscopy. Quantitative image analysis was used to measure the tracer-labeled fraction and to examine co-localization with trabecular pigmentation and the location of collector channel ostia. RESULTS Tracer distribution was segmental over both macro-scale and micro-scale dimensions. No more than approximately one-third of the trabecular meshwork appeared to be filtration-active on the macro scale (29%±5%; mean±SD) and micro scale (21%±6%). There was weak co-localization between macro-scale tracer intensity and pigmentation (r=0.17, P=0.017), and collector channel ostia tended to coincide with regions of high macro-scale tracer intensity. Tracer patterns were relatively insensitive to changing IOP over hour-long time scales and did not correlate with outflow facility. CONCLUSIONS Filtration patterns in human trabecular meshwork appear segmental over both macro-scale and micro-scale dimensions, with only approximately one-third of the trabecular meshwork actively contributing to outflow. Segmental outflow may limit the efficacy of outflow drugs by preventing delivery to non-filtering trabecular regions that may contribute the most to outflow obstruction in glaucoma.
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Affiliation(s)
- Jason Y H Chang
- 1 Department of Bioengineering, Imperial College London , London, United Kingdom
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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: 117] [Impact Index Per Article: 11.7] [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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69
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Pokrovskaya O, Wallace D, O’Brien C. The Emerging Role of Statins in Glaucoma Pathological Mechanisms and Therapeutics. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/ojoph.2014.44021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
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Abu-Hassan DW, Acott TS, Kelley MJ. The Trabecular Meshwork: A Basic Review of Form and Function. ACTA ACUST UNITED AC 2014; 2. [PMID: 25356439 DOI: 10.13188/2334-2838.1000017] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Diala W Abu-Hassan
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, Oregon, USA
| | - Ted S Acott
- Department of Biochemistry & Molecular Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Mary J Kelley
- Department of Biochemistry & Physiology, University of Jordan, Amman, Jordan
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Boussommier-Calleja A, Overby DR. The influence of genetic background on conventional outflow facility in mice. Invest Ophthalmol Vis Sci 2013; 54:8251-8. [PMID: 24235015 DOI: 10.1167/iovs.13-13025] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Intraocular pressure (IOP) varies between genetically distinct strains of mice. The purpose was to test the hypothesis that strain-dependent differences in IOP are attributable to differences in conventional outflow facility (C). METHODS The IOP was measured by rebound tonometry in conscious or anesthetized BALB/cJ, C57BL/6J, and CBA/J mice (N = 6-10 per strain). Conventional outflow facility was measured by ex vivo perfusion of enucleated eyes (N = 9-10 per strain). RESULTS Conscious IOP varied between strains, being highest in CBA/J (14.5 ± 0.9 mm Hg, mean ± SD), intermediate in C57BL/6J (12.3 ± 1.0 mm Hg), and lowest in BALB/cJ (10.6 ± 1.8 mm Hg) mice. Anesthesia reduced IOP and eliminated any detectable differences between strains. Conventional outflow facility also varied between strains, but, in contrast to IOP, C was lowest in CBA/J (0.0113 ± 0.0031 μL/min/mm Hg) and highest in BALB/cJ (0.0164 ± 0.0059 μL/min/mm Hg). Like IOP, C was intermediate in C57BL/6J (0.0147 ± 0.0029 μL/min/mm Hg). There was a strong correlation between conscious IOP and outflow resistance (1/C) from individual eyes across all three strains, revealing that 70% of the variation in IOP was attributable to variation in outflow resistance. CONCLUSIONS Differences in IOP among three genetically distinct murine strains are attributable largely to differences in conventional outflow facility. These results motivate further studies using mice to identify the morphologic and genetic factors that underlie IOP regulation within the conventional outflow pathway.
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Yang CYC, Liu Y, Lu Z, Ren R, Gong H. Effects of Y27632 on aqueous humor outflow facility with changes in hydrodynamic pattern and morphology in human eyes. Invest Ophthalmol Vis Sci 2013; 54:5859-70. [PMID: 23920374 DOI: 10.1167/iovs.12-10930] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
PURPOSE To determine the effect of Y27632, a Rho-kinase inhibitor on aqueous outflow facility, flow pattern, and juxtacanalicular tissue (JCT)/trabecular meshwork (TM) morphology in human eyes. METHODS Sixteen enucleated human eyes were perfused with PBS plus glucose (GPBS) at 15 mm Hg to establish the baseline outflow facility. Six eyes were perfused for short-duration (30 minute) with either 50 μM Y27632 or GPBS (n = 3 per group). Ten eyes were perfused for long duration (3 hours) with either 50 μM Y27632 or GPBS (n = 5 per group). Outflow pattern was labeled using fluorescent microspheres, and effective filtration length (EFL) was measured. Morphologic changes and their relationship to EFL and facility were analyzed. RESULTS Outflow facility significantly increased after short-duration perfusion with Y27632 compared with its own baseline (P = 0.03), but did not reach statistical significance compared with its controls (P = 0.07). Outflow facility (P = 0.01) and EFL (P < 0.05) were significantly increased after long-duration perfusion with Y27632 compared with its controls. Increases in outflow facility and EFL demonstrated a positive correlation. Morphologically, the TM and JCT of high-tracer regions were more expanded compared with low-tracer regions. A significant increase in JCT thickness was found in the long-duration Y27632 group compared with its control group (10.0 vs. 8.0 μm, P < 0.01). CONCLUSIONS Y27632 increases outflow facility in human eyes. This increase correlates positively with an increase in EFL, which is associated with an increased expansion in the JCT. Our data suggest that EFL could serve as a novel parameter to correlate with outflow facility.
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Affiliation(s)
- Chen-Yuan Charlie Yang
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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Zhu JY, Ye W, Wang T, Gong HY. Reversible changes in aqueous outflow facility, hydrodynamics, and morphology following acute intraocular pressure variation in bovine eyes. Chin Med J (Engl) 2013; 126:1451-1457. [PMID: 23595376 PMCID: PMC3771502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023] Open
Abstract
BACKGROUND Elevated intraocular pressure (IOP) is primarily due to increased aqueous outflow resistance, but how aqueous outflow resistance is generated and regulated are still not fully understood. The aim of this study is to determine whether changes in outflow facility, outflow pattern, and morphology following acute IOP elevation were reversible when the IOP was returned to a normal level in bovine eyes using a two-color tracer technique to label outflow patterns within the same eye. METHODS Twelve fresh enucleated bovine eyes were perfused with Dulbecco's phosphate buffer saline (PBS) containing 5.5 mmol/L glucose (DBG) at 30 mmHg first to establish the baseline outflow facility followed by a fixed volume of red fluorescent microspheres (0.5 µm, 0.002% v/v). After the red tracer being replaced with DBG in the anterior chamber, perfusion was continued at 7 mmHg with the same volume of green tracer, followed by a fixative. In two control groups, the eyes were constantly perfused at either 30 mmHg (n = 6) or 7 mmHg (n = 6) using the same methods. The outflow facility (C, µl × min × (-1)mmHg(-1)), was continuously recorded. Confocal images were taken along the inner wall (IW) of the aqueous plexus (AP) in frontal sections. The percent of the effective filtration length (PEFL, PEFL = IW length exhibiting tracer labeling/total length of IW) was measured. Sections with AP were processed and examined by light microscopy. The total length of IW and the length exhibiting separation (SL) in the juxtacanalicular connective tissue (JCT) were measured. A minimum of eight collector channel (CC) ostia per eye were analyzed for herniations. RESULTS In the experimental (30 - 7 mmHg) group, the outflow facility was significantly higher at 7 mmHg ((4.81 - 1.33) µl × min × (-1)mmHg(-1)) than that at 30 mmHg ((0.99 ± 0.15) µl × min × (-1)mmHg(-1), P = 0.002), corresponding to a significant increase in the PEFL (P = 0.0003). The percent of CC ostia exhibiting herniations in the experimental group ((67.40 ± 8.90) µl × min × (-1)mmHg(-1)) decreased significantly compared to that in the control at 30 mmHg ((94.44 ± 3.33) µl × min × (-1)mmHg(-1), P = 0.03), but higher than that in the control at 7 mmHg ((29.43 ± 4.60) µl × min × (-1)mmHg(-1), P = 0.01). Washout-associated separation between the IW and JCT was found by light microscopy and percent separation length (PSL, PSL = SL/total length of IW) was decreased in the control at 30 mmHg compared to that in the experimental group and control at 7 mmHg. CONCLUSIONS The pressure-induced morphological and hydrodynamic changes were reversible. Changes (collapse of AP, separation between the JCT and IW, and herniation into CC ostia) influence the effective filtration area that regulates outflow facility.
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Affiliation(s)
- Jing-ying Zhu
- Department of Ophthalmology, Huashan Hospital of Fudan University, Shanghai 200040, China; Department of Ophthalmology, Huadong Hospital of Fudan University, Shanghai 200040, China; Department of Ophthalmology, Boston University School of Medicine, Boston, MA 02118, USA
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