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Li M, Chen L, Luo Z, Yan X. The anterior scleral thickness in primary open-angle glaucoma with high myopia. Front Med (Lausanne) 2024; 11:1356839. [PMID: 39005651 PMCID: PMC11239357 DOI: 10.3389/fmed.2024.1356839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Accepted: 06/17/2024] [Indexed: 07/16/2024] Open
Abstract
Purpose This study aimed to investigate and compare the anterior scleral thickness (AST) among high myopia (HM), primary open-angle glaucoma (POAG), and POAG with HM (HMPOAG) groups. Methods Thirty-two HM eyes, 30 POAG eyes, and 31 HMPOAG eyes were included. The Schlemm's canal (SC) area, trabecular meshwork (TM) thickness, scleral spur (SS) length, and AST were measured using swept-source optical coherence tomography. AST was measured at 0 mm (AST0), 1 mm (AST1), 2 mm (AST2), and 3 mm (AST3) from SS. Results The HMPOAG group had significantly thinner AST, SS length, and TM thickness than the HM and POAG groups (all p < 0.05). In addition, the SC area of the HMPOAG group was also significantly smaller than that of the HM group (p < 0.001). Conclusion The HMPOAG group had the thinnest AST, shortest SS, thinnest TM, and smallest SC. The thinnest AST might contribute to the shortest SS, and further to the thinnest TM and smallest SC in the HMPOAG group. AST might be a novel clinical indicator in the prediction and evaluation of POAG.
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Affiliation(s)
- Mu Li
- Department of Ophthalmology, Wuhan Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Liwen Chen
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhaoxia Luo
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoqin Yan
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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2
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Benagiano V, Rizzi A, Sannace C, Alessio G, Ribatti D, Dammacco R. Aqueous humor as eye lymph: A crossroad between venous and lymphatic system. Exp Eye Res 2024; 243:109904. [PMID: 38642600 DOI: 10.1016/j.exer.2024.109904] [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: 12/15/2023] [Revised: 03/18/2024] [Accepted: 04/17/2024] [Indexed: 04/22/2024]
Abstract
Aqueous humor (AQH) is a transparent fluid with characteristics similar to those of the interstitial fluid, which fills the eyeball posterior and anterior chambers and circulates in them from the sites of production to those of drainage. The AQH volume and pressure homeostasis is essential for the trophism of the ocular avascular tissues and their normal structure and function. Different AQH outflow pathways exist, including a main pathway, quite well defined anatomically and referred to as the conventional pathway, and some accessory pathways, more recently described and still not fully morphofunctionally understood, generically referred to as unconventional pathways. The conventional pathway is based on the existence of a series of conduits starting with the trabecular meshwork and Schlemm's Canal and continuing with a system of intrascleral and episcleral venules, which are tributaries to veins of the anterior segment of the eyeball. The unconventional pathways are mainly represented by the uveoscleral pathway, in which AQH flows through clefts, interstitial conduits located in the ciliary body and sclera, and then merges into the aforementioned intrascleral and episcleral venules. A further unconventional pathway, the lymphatic pathway, has been supported by the demonstration of lymphatic microvessels in the limbal sclera and, possibly, in the uvea (ciliary body, choroid) as well as by the ocular glymphatic channels, present in the neural retina and optic nerve. It follows that AQH may be drained from the eyeball through blood vessels (TM-SC pathway, US pathway) or lymphatic vessels (lymphatic pathway), and the different pathways may integrate or compensate for each other, optimizing the AQH drainage. The present review aims to define the state-of-the-art concerning the structural organization and the functional anatomy of all the AQH outflow pathways. Particular attention is paid to examining the regulatory mechanisms active in each of them. The new data on the anatomy and physiology of AQH outflow pathways is the key to understanding the pathophysiology of AQH outflow disorders and could open the way for novel approaches to their treatment.
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Affiliation(s)
- Vincenzo Benagiano
- Department of Translational Biomedicine and Neuroscience, University of Bari 'Aldo Moro', Bari, Italy.
| | - Anna Rizzi
- Department of Translational Biomedicine and Neuroscience, University of Bari 'Aldo Moro', Bari, Italy
| | - Carmela Sannace
- Azienda Sanitaria Locale Bari, Ophthalmology Day Service Triggiano-Gioia del Colle, Bari, Italy
| | - Giovanni Alessio
- Department of Translational Biomedicine and Neuroscience, University of Bari 'Aldo Moro', Bari, Italy
| | - Domenico Ribatti
- Department of Translational Biomedicine and Neuroscience, University of Bari 'Aldo Moro', Bari, Italy
| | - Rosanna Dammacco
- Department of Translational Biomedicine and Neuroscience, University of Bari 'Aldo Moro', Bari, Italy
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3
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Beardslee LA, Halman JR, Unser AM, Xie Y, Danias J, Bergkvist M, Sharfstein ST, Torrejon KY. Recreating the Trabecular Outflow Tissue on Implantable, Micropatterned, Ultrathin, Porous Polycaprolactone Scaffolds. Bioengineering (Basel) 2023; 10:679. [PMID: 37370610 PMCID: PMC10294786 DOI: 10.3390/bioengineering10060679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 05/17/2023] [Accepted: 05/28/2023] [Indexed: 06/29/2023] Open
Abstract
Glaucoma, where increased intraocular pressure (IOP) leads to damage to the optic nerve and loss of sight, is amongst the foremost causes of irreversible blindness worldwide. In primary open angle glaucoma, the increased IOP is a result of the malfunctioning human trabecular meshwork (HTM) cells' inability to properly regulate the outflow of aqueous humor from the eye. A potential future treatment for glaucoma is to replace damaged HTM cells with a tissue-engineered substitute, thus restoring proper fluid outflow. Polycaprolactone (PCL) is a versatile, biodegradable, and implantable material that is widely used for cell culture and tissue engineering. In this work, PCL scaffolds were lithographically fabricated using a sacrificial process to produce submicron-thick scaffolds with openings of specific sizes and shapes (e.g., grid, hexagonal pattern). The HTM cell growth on gelatin-coated PCL scaffolds was assessed by scanning electron microscopy, tetrazolium metabolic activity assay, and cytoskeletal organization of F-actin. Expression of HTM-specific markers and ECM deposition were assessed by immunocytochemistry and qPCR analysis. Gelatin-coated, micropatterned, ultrathin, porous PCL scaffolds with a grid pattern supported proper HTM cell growth, cytoskeleton organization, HTM-marker expression, and ECM deposition, demonstrating the feasibility of using these PCL scaffolds to tissue-engineer implantable, healthy ocular outflow tissue.
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Affiliation(s)
- Luke A. Beardslee
- Colleges of Nanoscale Science and Engineering, SUNY Polytechnic Institute, 257 Fuller Road, Albany, NY 12203, USA
| | - Justin R. Halman
- Colleges of Nanoscale Science and Engineering, SUNY Polytechnic Institute, 257 Fuller Road, Albany, NY 12203, USA
| | - Andrea M. Unser
- Department of Ophthalmology, SUNY Downstate Health Sciences University, 450 Clackson Avenue, Brooklyn, NY 11203, USA
| | - Yubing Xie
- Colleges of Nanoscale Science and Engineering, SUNY Polytechnic Institute, 257 Fuller Road, Albany, NY 12203, USA
| | - John Danias
- Department of Ophthalmology, SUNY Downstate Health Sciences University, 450 Clackson Avenue, Brooklyn, NY 11203, USA
| | - Magnus Bergkvist
- Colleges of Nanoscale Science and Engineering, SUNY Polytechnic Institute, 257 Fuller Road, Albany, NY 12203, USA
| | - Susan T. Sharfstein
- Colleges of Nanoscale Science and Engineering, SUNY Polytechnic Institute, 257 Fuller Road, Albany, NY 12203, USA
| | - Karen Y. Torrejon
- Colleges of Nanoscale Science and Engineering, SUNY Polytechnic Institute, 257 Fuller Road, Albany, NY 12203, USA
- Glauconix Biosciences Inc., 251 Fuller Road, Albany, NY 12203, USA
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4
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Karimi A, Crouch DJ, Razaghi R, Crawford Downs J, Acott TS, Kelley MJ, Behnsen JG, Bosworth LA, Sheridan CM. Morphological and biomechanical analyses of the human healthy and glaucomatous aqueous outflow pathway: Imaging-to-modeling. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 236:107485. [PMID: 37149973 DOI: 10.1016/j.cmpb.2023.107485] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/09/2023] [Accepted: 03/13/2023] [Indexed: 05/09/2023]
Abstract
BACKGROUND AND OBJECTIVE Intraocular pressure (IOP) is maintained via a dynamic balance between the production of aqueous humor and its drainage through the trabecular meshwork (TM), juxtacanalicular connective tissue (JCT), and Schlemm's canal (SC) endothelium of the conventional outflow pathway. Primary open angle glaucoma (POAG) is often associated with IOP elevation that occurs due to an abnormally high outflow resistance across the outflow pathway. Outflow tissues are viscoelastic and actively interact with aqueous humor dynamics through a two-way fluid-structure interaction coupling. While glaucoma affects the morphology and stiffness of the outflow tissues, their biomechanics and hydrodynamics in glaucoma eyes remain largely unknown. This research aims to develop an image-to-model method allowing the biomechanics and hydrodynamics of the conventional aqueous outflow pathway to be studied. METHODS We used a combination of X-ray computed tomography and scanning electron microscopy to reconstruct high-fidelity, eye-specific, 3D microstructural finite element models of the healthy and glaucoma outflow tissues in cellularized and decellularized conditions. The viscoelastic TM/JCT/SC complex finite element models with embedded viscoelastic beam elements were subjected to a physiological IOP load boundary; the stresses/strains and the flow state were calculated using fluid-structure interaction and computational fluid dynamics. RESULTS Based on the resultant hydrodynamics parameters across the outflow pathway, the primary site of outflow resistance in healthy eyes was in the JCT and immediate vicinity of the SC inner wall, while the majority of the outflow resistance in the glaucoma eyes occurred in the TM. The TM and JCT in the glaucoma eyes showed 1.32-fold and 1.13-fold larger beam thickness and smaller trabecular space size (2.24-fold and 1.50-fold) compared to the healthy eyes. CONCLUSIONS Characterizing the accurate morphology of the outflow tissues may significantly contribute to constructing more accurate, robust, and reliable models, that can eventually help to better understand the dynamic IOP regulation, hydrodynamics of the aqueous humor, and outflow resistance dynamic in the human eyes. This model demonstrates proof of concept for determining changes to outflow resistance in healthy and glaucomatous tissues and thus may be utilized in larger cohorts of donor tissues where disease specificity, race, age, and gender of the eye donors may be accounted for.
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Affiliation(s)
- Alireza Karimi
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Devon J Crouch
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L7 8TX, United Kingdom
| | - Reza Razaghi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, United States
| | - J Crawford Downs
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Ted S Acott
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States; Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon, United States
| | - Mary J Kelley
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States; Department of Integrative Biosciences, Oregon Health & Science University, Portland, Oregon, United States
| | - Julia G Behnsen
- Department of Mechanical, Materials, and Aerospace Engineering, University of Liverpool, Liverpool, L69 6GB, United Kingdom
| | - Lucy A Bosworth
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L7 8TX, United Kingdom
| | - Carl M Sheridan
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L7 8TX, United Kingdom.
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Wang J, Rong Y, Liu Y, Zhu M, Chen W, Chen Z, Guo J, Deng C, Manyande A, Wang P, Zhang H, Xiang Y. The effect of ET1-CTGF mediated pathway on the accumulation of extracellular matrix in the trabecular meshwork and its contribution to the increase in IOP. Int Ophthalmol 2023:10.1007/s10792-023-02733-y. [PMID: 37160587 DOI: 10.1007/s10792-023-02733-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 04/22/2023] [Indexed: 05/11/2023]
Abstract
PURPOSE To investigate the effect of endothelin-1 (ET-1) in excessive accumulation of extracellular matrix (ECM) of the trabecular meshwork (TM) and its role in intraocular pressure (IOP) regulation. METHODS Cultured human TM cells (HTMCs) were treated with ET-1, ET-1 + ETA receptor (ETAR) antagonist BQ123, ET-1 + ETB receptor (ETBR) antagonist BQ788. The expressions of fibronectin (FN) and collagen type IV (Col IV) were evaluated by western blotting and immunofluorescence. A time course effect of ET-1 on the transcription level of connective tissue growth factor (CTGF) was investigated by qRT-PCR. Next, the transcription level of CTGF was downregulated by using antisense oligodeoxynucleotide sequence. Then HTMCs were treated with ET-1, and the expression levels of FN and Col IV were evaluated by western blotting. In addition, by using an ex-vivo model of cultured anterior eye segment, we explored the effect of ET-1 on IOP changes and the expressions of FN and Col IV. RESULTS In cultured HTMCs, the expressions of FN and Col IV were significantly increased after ET-1 treatment, which were blocked by the pretreatment of ETAR antagonist BQ123, rather than ETBR antagonist BQ788. Besides, the CTGF mRNA level increased significantly and reached a peak after 48 h of ET-1 treatment. However, the effect of ET-1 on increasing the expressions of FN and Col IV in HTMCs could be inhibited by the downregulation of CTGF. In an ex-vivo model, IOP increased significantly after ET-1 administration, which could be blocked by BQ123 but not by BQ788. Furthermore, elevated expressions of FN and Col IV in TM were observed after ET-1 perfusion, and could be inhibited by BQ123 pretreatment. CONCLUSION Excessive ET-1 in aqueous humor could lead to the abnormal accumulation of FN and Col IV in TM via the ETA-CTGF pathway, thereby increasing IOP.
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Affiliation(s)
- Junming Wang
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Road, Wuhan, 430030, Hubei, China
| | - Yan Rong
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Road, Wuhan, 430030, Hubei, China
| | - Ying Liu
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Road, Wuhan, 430030, Hubei, China
| | - Mengxia Zhu
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Road, Wuhan, 430030, Hubei, China
| | - Wei Chen
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Road, Wuhan, 430030, Hubei, China
| | - Zhiqi Chen
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Road, Wuhan, 430030, Hubei, China
| | - Jingmin Guo
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Road, Wuhan, 430030, Hubei, China
| | - Chaohua Deng
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Road, Wuhan, 430030, Hubei, China
| | - Anne Manyande
- School of Human and Social Sciences, University of West London, London, UK
| | - Ping Wang
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Road, Wuhan, 430030, Hubei, China
| | - Hong Zhang
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Road, Wuhan, 430030, Hubei, China
| | - Yan Xiang
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Road, Wuhan, 430030, Hubei, China.
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6
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Catania F, Morenghi E, Rosetta P, Paolo V, Vinciguerra R. Corneal Biomechanics Assessment with Ultra High Speed Scheimpflug Camera in Primary Open Angle Glaucoma Compared with Healthy Subjects: A meta-analysis of the Literature. Curr Eye Res 2023; 48:161-171. [PMID: 35385343 DOI: 10.1080/02713683.2022.2059809] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
PURPOSE The aim of this meta-analysis of the literature is to provide a comprehensive analysis of the differences in Corvis ST dynamic corneal response (DCR) parameters between primary open-angle glaucoma (POAG) patients and healthy controls. METHODS A quantitative meta-analysis was conducted on articles published before September 10, 2021 identified by searching PubMed, EMBASE, and Web of Science. Prospective studies comparing DCR Corvis ST parameter in high tension POAG and healthy controls were included. The random-effects model was conducted. Assessment of heterogeneity was based on the calculation of I2. Funnel plots evaluation and meta-regression were performed in case of detection of high heterogeneity. RESULTS The selection process resulted in the inclusion of six articles. Pooled analysis revealed that POAG corneas respond to mechanical stimulus with a smaller concavity, showing lower deformation amplitude (DA) (CI95% -0.991 to -0.578; p < .001; I2 = 0%), higher highest concavity radius (HCR; confidence interval [CI]95% -0.01 to 0.34; p = .058; I2 = 6.7%), and lower peak distance (PD; CI95% -1.06 to -0.024; p = .040; I2 = 86.5%). They also show a slower loading phase, with lower highest concavity time (HCT; CI95% -0.39 to -0.02; p = .029; I2 = 3.3%) and lower applanation velocity-1 (CI95% -0.641 to -0.127; p = .003; I2 = 34.6%), and a faster restoration to the original form, shown by lower applanation time-2 (CI95% -1.123 to -0.544; p = .001; I2 = 44.8%) compared to healthy subjects. CONCLUSIONS High tension POAG patients are characterized by stiffer corneas compared to healthy controls. These differences are valid also after removing the effect of age, corneal thickness, and intraocular pressure (IOP).
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Affiliation(s)
- Fiammetta Catania
- Department of Biomedical Sciences, Humanitas University, Milan, Italy.,Humanitas Clinical and Research Center, IRCCS, Rozzano, Italy
| | - Emanuela Morenghi
- Department of Biomedical Sciences, Humanitas University, Milan, Italy.,Humanitas Clinical and Research Center, IRCCS, Rozzano, Italy
| | | | - Vinciguerra Paolo
- Department of Biomedical Sciences, Humanitas University, Milan, Italy.,Humanitas Clinical and Research Center, IRCCS, Rozzano, Italy
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Fowler S, Wang T, Munro D, Kumar A, Chitre AS, Hollingsworth TJ, Garcia Martinez A, St. Pierre CL, Bimschleger H, Gao J, Cheng R, Mohammadi P, Chen H, Palmer AA, Polesskaya O, Jablonski MM. Genome-wide association study finds multiple loci associated with intraocular pressure in HS rats. Front Genet 2023; 13:1029058. [PMID: 36793389 PMCID: PMC9922724 DOI: 10.3389/fgene.2022.1029058] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 12/28/2022] [Indexed: 02/03/2023] Open
Abstract
Elevated intraocular pressure (IOP) is influenced by environmental and genetic factors. Increased IOP is a major risk factor for most types of glaucoma, including primary open angle glaucoma (POAG). Investigating the genetic basis of IOP may lead to a better understanding of the molecular mechanisms of POAG. The goal of this study was to identify genetic loci involved in regulating IOP using outbred heterogeneous stock (HS) rats. HS rats are a multigenerational outbred population derived from eight inbred strains that have been fully sequenced. This population is ideal for a genome-wide association study (GWAS) owing to the accumulated recombinations among well-defined haplotypes, the relatively high allele frequencies, the accessibility to a large collection of tissue samples, and the large allelic effect size compared to human studies. Both male and female HS rats (N = 1,812) were used in the study. Genotyping-by-sequencing was used to obtain ∼3.5 million single nucleotide polymorphisms (SNP) from each individual. SNP heritability for IOP in HS rats was 0.32, which agrees with other studies. We performed a GWAS for the IOP phenotype using a linear mixed model and used permutation to determine a genome-wide significance threshold. We identified three genome-wide significant loci for IOP on chromosomes 1, 5, and 16. Next, we sequenced the mRNA of 51 whole eye samples to find cis-eQTLs to aid in identification of candidate genes. We report 5 candidate genes within those loci: Tyr, Ctsc, Plekhf2, Ndufaf6 and Angpt2. Tyr, Ndufaf6 and Angpt2 genes have been previously implicated by human GWAS of IOP-related conditions. Ctsc and Plekhf2 genes represent novel findings that may provide new insight into the molecular basis of IOP. This study highlights the efficacy of HS rats for investigating the genetics of elevated IOP and identifying potential candidate genes for future functional testing.
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Affiliation(s)
- Samuel Fowler
- Hamilton Eye Institute Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United states
| | - Tengfei Wang
- Department of Pharmacology, Addiction Science and Toxicology, University of Tennessee Health Science Center, Memphis, Tennessee, United states
| | - Daniel Munro
- Department of Psychiatry, University of California, San Diego, San Diego, California, United states
- Department of Integrative Structural and Computational Biology, Scripps Research, San Diego, California, United states
| | - Aman Kumar
- Hamilton Eye Institute Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United states
| | - Apurva S. Chitre
- Department of Psychiatry, University of California, San Diego, San Diego, California, United states
| | - T. J. Hollingsworth
- Hamilton Eye Institute Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United states
| | - Angel Garcia Martinez
- Department of Pharmacology, Addiction Science and Toxicology, University of Tennessee Health Science Center, Memphis, Tennessee, United states
| | - Celine L. St. Pierre
- Department of Psychiatry, University of California, San Diego, San Diego, California, United states
| | - Hannah Bimschleger
- Department of Psychiatry, University of California, San Diego, San Diego, California, United states
| | - Jianjun Gao
- Department of Psychiatry, University of California, San Diego, San Diego, California, United states
| | - Riyan Cheng
- Department of Psychiatry, University of California, San Diego, San Diego, California, United states
| | - Pejman Mohammadi
- Department of Integrative Structural and Computational Biology, Scripps Research, San Diego, California, United states
- Scripps Research Translational Institute, Scripps Research, San Diego, California, United states
| | - Hao Chen
- Department of Pharmacology, Addiction Science and Toxicology, University of Tennessee Health Science Center, Memphis, Tennessee, United states
| | - Abraham A. Palmer
- Department of Psychiatry, University of California, San Diego, San Diego, California, United states
- Institute for Genomic Medicine, University of California, San Diego, San Diego, California, United states
| | - Oksana Polesskaya
- Department of Psychiatry, University of California, San Diego, San Diego, California, United states
| | - Monica M. Jablonski
- Hamilton Eye Institute Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United states
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8
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Karimi A, Razaghi R, Rahmati SM, Downs JC, Acott TS, Kelley MJ, Wang RK, Johnstone M. The Effect of Intraocular Pressure Load Boundary on the Biomechanics of the Human Conventional Aqueous Outflow Pathway. Bioengineering (Basel) 2022; 9:672. [PMID: 36354583 PMCID: PMC9687513 DOI: 10.3390/bioengineering9110672] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 10/28/2022] [Accepted: 11/08/2022] [Indexed: 09/29/2023] Open
Abstract
BACKGROUND Aqueous humor outflow resistance in the trabecular meshwork (TM), juxtacanalicular connective tissue (JCT), and Schlemm's canal (SC) endothelium of the conventional outflow pathway actively contribute to intraocular pressure (IOP) regulation. Outflow resistance is actively affected by the dynamic outflow pressure gradient across the TM, JCT, and SC inner wall tissues. The resistance effect implies the presence of a fluid-structure interaction (FSI) coupling between the outflow tissues and the aqueous humor. However, the biomechanical interactions between viscoelastic outflow tissues and aqueous humor dynamics are largely unknown. METHODS A 3D microstructural finite element (FE) model of a healthy human eye TM/JCT/SC complex was constructed with elastic and viscoelastic material properties for the bulk extracellular matrix and embedded elastic cable elements. The FE models were subjected to both idealized and a physiologic IOP load boundary using the FSI method. RESULTS The elastic material model for both the idealized and physiologic IOP load boundary at equal IOPs showed similar stresses and strains in the outflow tissues as well as pressure in the aqueous humor. However, outflow tissues with viscoelastic material properties were sensitive to the IOP load rate, resulting in different mechanical and hydrodynamic responses in the tissues and aqueous humor. CONCLUSIONS Transient IOP fluctuations may cause a relatively large IOP difference of ~20 mmHg in a very short time frame of ~0.1 s, resulting in a rate stiffening in the outflow tissues. Rate stiffening reduces strains and causes a rate-dependent pressure gradient across the outflow tissues. Thus, the results suggest it is necessary to use a viscoelastic material model in outflow tissues that includes the important role of IOP load rate.
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Affiliation(s)
- Alireza Karimi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Reza Razaghi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | | | - J. Crawford Downs
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Ted S. Acott
- Departments of Ophthalmology and Biochemistry and Molecular Biology, Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Mary J. Kelley
- Departments of Ophthalmology and Integrative Biosciences, Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Ruikang K. Wang
- Department of Ophthalmology, University of Washington, Seattle, WA 98195, USA
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Murray Johnstone
- Department of Ophthalmology, University of Washington, Seattle, WA 98195, USA
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9
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Karimi A, Razaghi R, Padilla S, Rahmati SM, Downs JC, Acott TS, Kelley MJ, Wang RK, Johnstone M. Viscoelastic Biomechanical Properties of the Conventional Aqueous Outflow Pathway Tissues in Healthy and Glaucoma Human Eyes. J Clin Med 2022; 11:6049. [PMID: 36294371 PMCID: PMC9605362 DOI: 10.3390/jcm11206049] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 10/11/2022] [Accepted: 10/12/2022] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Although the tissues comprising the ocular conventional outflow pathway have shown strong viscoelastic mechanical response to aqueous humor pressure dynamics, the viscoelastic mechanical properties of the trabecular meshwork (TM), juxtacanalicular connective tissue (JCT), and Schlemm's canal (SC) inner wall are largely unknown. METHODS A quadrant of the anterior segment from two human donor eyes at low- and high-flow (LF and HF) outflow regions was pressurized and imaged using optical coherence tomography (OCT). A finite element (FE) model of the TM, the adjacent JCT, and the SC inner wall was constructed and viscoelastic beam elements were distributed in the extracellular matrix (ECM) of the TM and JCT to represent anisotropic collagen. An inverse FE-optimization algorithm was used to calculate the viscoelastic properties of the ECM/beam elements such that the TM/JCT/SC model and OCT imaging data best matched over time. RESULTS The ECM of the glaucoma tissues showed significantly larger time-dependent shear moduli compared to the heathy tissues. Significantly larger shear moduli were also observed in the LF regions of both the healthy and glaucoma eyes compared to the HF regions. CONCLUSIONS The outflow tissues in both glaucoma eyes and HF regions are stiffer and less able to respond to dynamic IOP.
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Affiliation(s)
- Alireza Karimi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Reza Razaghi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Steven Padilla
- Department of Ophthalmology, University of Washington, Seattle, WA 98109, USA
| | | | - J. Crawford Downs
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Ted S. Acott
- Departments of Ophthalmology and Biochemistry and Molecular Biology, Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Mary J. Kelley
- Departments of Ophthalmology and Integrative Biosciences, Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Ruikang K. Wang
- Department of Ophthalmology, University of Washington, Seattle, WA 98109, USA
- Department of Bioengineering, University of Washington, Seattle, WA 98105, USA
| | - Murray Johnstone
- Department of Ophthalmology, University of Washington, Seattle, WA 98109, USA
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10
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Carmichael-Martins A, Gast TJ, Burns SA, Walker BR, King BJ. Characterization of the human iridocorneal angle in vivo using a custom design goniolens with OCT gonioscopy. BIOMEDICAL OPTICS EXPRESS 2022; 13:4652-4667. [PMID: 36187241 PMCID: PMC9484429 DOI: 10.1364/boe.465317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 07/18/2022] [Accepted: 07/27/2022] [Indexed: 06/16/2023]
Abstract
Intraocular pressure (IOP) is the only modifiable risk factor for glaucoma progression, and many treatments target the trabecular meshwork (TM). Imaging this region in vivo is challenging due to optical limitations of imaging through the cornea at high angles. We propose a gonioscopic OCT approach using a custom goniolens and a commercially available OCT device to improve imaging of the TM, Schlemm's canal (SC) and adjacent structures within the iridocorneal angle (ICA). The goniolens is modified with a plano-convex focusing lens and placed on the eye optically mated with goniogel and aided by a 3D adjustable mount. Gonioscopic OCT volume scans are acquired to image SC. Transverse enface images allowed measurements of SC over a 45° section of the ICA for the first time and revealed locations of SC narrowing. The band of extracanalicular limbal lamina and corneoscleral bands were imaged in most subjects and these bands were confirmed using exterior OCT imaging. The polarization dependence of the visibility of these structures is studied by polarization rotation the OCT beam with a half-wave plate, allowing increased contrast of SC. Gonioscopic OCT has successfully been used to image the human ICA in 3D in vivo. This approach provides more detailed characterization of the TM and SC, enhancing their contrast against their birefringent backgrounds.
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Affiliation(s)
| | - Thomas J. Gast
- School of Optometry, Indiana University, Bloomington, Indiana 47401, USA
| | - Stephen A. Burns
- School of Optometry, Indiana University, Bloomington, Indiana 47401, USA
| | - Brittany R. Walker
- School of Optometry, Indiana University, Bloomington, Indiana 47401, USA
| | - Brett J. King
- School of Optometry, Indiana University, Bloomington, Indiana 47401, USA
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11
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Mzyk P, Hernandez H, Le T, Ramirez JR, McDowell CM. Toll-Like Receptor 4 Signaling in the Trabecular Meshwork. Front Cell Dev Biol 2022; 10:936115. [PMID: 35912101 PMCID: PMC9335276 DOI: 10.3389/fcell.2022.936115] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 06/21/2022] [Indexed: 12/04/2022] Open
Abstract
Primary open-angle glaucoma is one of the leading causes of blindness worldwide. With limited therapeutics targeting the pathogenesis at the trabecular meshwork (TM), there is a great need for identifying potential new targets. Recent evidence has implicated Toll-like receptor 4 (TLR4) and it is signaling pathway in augmenting the effects of transforming growth factor beta-2 (TGFβ2) and downstream extracellular matrix production. In this review, we examine the role of TLR4 signaling in the trabecular meshwork and the interplay between endogenous activators of TLR4 (damage-associated molecular patterns (DAMPs)), extracellular matrix (ECM), and the effect on intraocular pressure.
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Affiliation(s)
- Philip Mzyk
- University of Wisconsin-Madison, Madison, WI, United States
| | | | - Thanh Le
- University of Houston-Victoria, Victoria, TX, United States
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12
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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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13
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McDowell CM, Kizhatil K, Elliott MH, Overby DR, van Batenburg-Sherwood J, Millar JC, Kuehn MH, Zode G, Acott TS, Anderson MG, Bhattacharya SK, Bertrand JA, Borras T, Bovenkamp DE, Cheng L, Danias J, De Ieso ML, Du Y, Faralli JA, Fuchshofer R, Ganapathy PS, Gong H, Herberg S, Hernandez H, Humphries P, John SWM, Kaufman PL, Keller KE, Kelley MJ, Kelly RA, Krizaj D, Kumar A, Leonard BC, Lieberman RL, Liton P, Liu Y, Liu KC, Lopez NN, Mao W, Mavlyutov T, McDonnell F, McLellan GJ, Mzyk P, Nartey A, Pasquale LR, Patel GC, Pattabiraman PP, Peters DM, Raghunathan V, Rao PV, Rayana N, Raychaudhuri U, Reina-Torres E, Ren R, Rhee D, Chowdhury UR, Samples JR, Samples EG, Sharif N, Schuman JS, Sheffield VC, Stevenson CH, Soundararajan A, Subramanian P, Sugali CK, Sun Y, Toris CB, Torrejon KY, Vahabikashi A, Vranka JA, Wang T, Willoughby CE, Xin C, Yun H, Zhang HF, Fautsch MP, Tamm ER, Clark AF, Ethier CR, Stamer WD. Consensus Recommendation for Mouse Models of Ocular Hypertension to Study Aqueous Humor Outflow and Its Mechanisms. Invest Ophthalmol Vis Sci 2022; 63:12. [PMID: 35129590 PMCID: PMC8842499 DOI: 10.1167/iovs.63.2.12] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 12/08/2021] [Indexed: 01/07/2023] Open
Abstract
Due to their similarities in anatomy, physiology, and pharmacology to humans, mice are a valuable model system to study the generation and mechanisms modulating conventional outflow resistance and thus intraocular pressure. In addition, mouse models are critical for understanding the complex nature of conventional outflow homeostasis and dysfunction that results in ocular hypertension. In this review, we describe a set of minimum acceptable standards for developing, characterizing, and utilizing mouse models of open-angle ocular hypertension. We expect that this set of standard practices will increase scientific rigor when using mouse models and will better enable researchers to replicate and build upon previous findings.
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Affiliation(s)
- Colleen M. McDowell
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | | | - Michael H. Elliott
- University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Darryl R. Overby
- Department of Bioengineering, Imperial College London, United Kingdom
| | | | - J. Cameron Millar
- Department of Pharmacology & Neuroscience, and North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Markus H. Kuehn
- Department of Ophthalmology and Visual Sciences and Institute for Vision Research, The University of Iowa; Center for the Prevention and Treatment of Visual Loss, Veterans Affairs Medical Center, Iowa City, Iowa, United States
| | - Gulab Zode
- Department of Pharmacology & Neuroscience, and North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Ted S. Acott
- Ophthalmology and Biochemistry and Molecular Biology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Michael G. Anderson
- Department of Molecular Physiology and Biophysics and Department of Ophthalmology and Visual Sciences, The University of Iowa; Center for the Prevention and Treatment of Visual Loss, Veterans Affairs Medical Center, Iowa City, Iowa, United States
| | | | - Jacques A. Bertrand
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Terete Borras
- University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
| | | | - Lin Cheng
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
| | - John Danias
- SUNY Downstate Health Sciences University, Brooklyn, New York, United States
| | - Michael Lucio De Ieso
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, North Carolina, United States
| | - Yiqin Du
- Department of Ophthalmology, University of Pittsburgh, Pennsylvania, United States
| | - Jennifer A. Faralli
- Department of Pathology and Laboratory Medicine, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Rudolf Fuchshofer
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
| | - Preethi S. Ganapathy
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, New York, United States
| | - Haiyan Gong
- Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Samuel Herberg
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, New York, United States
| | | | - Peter Humphries
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Simon W. M. John
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - Paul L. Kaufman
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Kate E. Keller
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Mary J. Kelley
- Department of Ophthalmology and Department of Integrative Biosciences, Oregon Health & Science University, Portland, Oregon, United States
| | - Ruth A. Kelly
- Ocular Genetics Unit, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - David Krizaj
- Department of Ophthalmology, University of Utah School of Medicine, Salt Lake City, Utah, United States
| | - Ajay Kumar
- Department of Ophthalmology, University of Pittsburgh, Pennsylvania, United States
| | - Brian C. Leonard
- Department of Surgical and Radiological Sciences, University of California, Davis, Davis, California, United States
| | - Raquel L. Lieberman
- Department of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, United States
| | - Paloma Liton
- Department of Ophthalmology and Department of Pathology, Duke University, Durham, North Carolina, United States
| | - Yutao Liu
- Department of Cellular Biology and Anatomy, James & Jean Culver Vision Discovery Institute, Augusta University, Augusta, Georgia, United States
| | - Katy C. Liu
- Duke Eye Center, Duke Health, Durham, North Carolina, United States
| | - Navita N. Lopez
- Department of Neurobiology, University of Utah, Salt Lake City, Utah, United States
| | - Weiming Mao
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Timur Mavlyutov
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Fiona McDonnell
- Duke Eye Center, Duke Health, Durham, North Carolina, United States
| | - Gillian J. McLellan
- Department of Surgical Sciences and Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Philip Mzyk
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Andrews Nartey
- College of Optometry, University of Houston, Houston, Texas, United States
| | - Louis R. Pasquale
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, New York, United States
| | - Gaurang C. Patel
- Ophthalmology Research, Regeneron Pharmaceuticals, Tarreytown, New York, United States
| | | | - Donna M. Peters
- Department of Pathology and Laboratory Medicine, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | | | - Ponugoti Vasantha Rao
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States
| | - Naga Rayana
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Urmimala Raychaudhuri
- Department of Neurobiology, University of California, Irvine, Irvine, California, United States
| | - Ester Reina-Torres
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Ruiyi Ren
- Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Douglas Rhee
- Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Uttio Roy Chowdhury
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - John R. Samples
- Washington State University, Floyd Elson College of Medicine, Spokane, Washington, United States
| | | | - Najam Sharif
- Santen Inc., Emeryville, California, United States
| | - Joel S. Schuman
- Department of Ophthalmology and Department of Physiology and Neuroscience, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, United States; Departments of Biomedical Engineering and Electrical and Computer Engineering, New York University Tandon School of Engineering, Brooklyn, New York, United States; Center for Neural Science, College of Arts and Science, New York University, New York, New York, United States
| | - Val C. Sheffield
- Department of Pediatrics and Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States
| | - Cooper H. Stevenson
- Department of Pharmacology & Neuroscience, and North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Avinash Soundararajan
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | | | - Chenna Kesavulu Sugali
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Yang Sun
- Veterans Affairs Palo Alto Health Care System, Stanford University, Palo Alto, California, United States
| | - Carol B. Toris
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States; Department of Ophthalmology and Vision Sciences, The Ohio State University, Columbus, Ohio, United States
| | | | - Amir Vahabikashi
- Cell and Developmental Biology Department, Northwestern University, Chicago, Illinois, United States
| | - Janice A. Vranka
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Ting Wang
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Colin E. Willoughby
- Genomic Medicine, Biomedical Sciences Research Institute, Ulster University, Coleraine, Northern Ireland, United Kingdom
| | - Chen Xin
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Hongmin Yun
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Hao F. Zhang
- Biomedical Engineering Department, Northwestern University, Evanston, Illinois, United States
| | - Michael P. Fautsch
- Biomedical Engineering Department, Northwestern University, Evanston, Illinois, United States
| | | | - Abbot F. Clark
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - C. Ross Ethier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology; Emory University School of Medicine, Emory University, Atlanta, Georgia, United States
| | - W. Daniel Stamer
- Duke Ophthalmology, Duke University, Durham, North Carolina, United States
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14
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Yan X, Li M, Chen Z, Zhou X. The anterior scleral thickness in eyes with primary open-angle glaucoma. Graefes Arch Clin Exp Ophthalmol 2022; 260:1601-1610. [PMID: 35067770 PMCID: PMC9007782 DOI: 10.1007/s00417-021-05523-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 12/07/2021] [Accepted: 12/14/2021] [Indexed: 11/24/2022] Open
Abstract
Abstract
Purpose
To investigate the anterior scleral thickness (AST) and its associations with Schlemm’s canal (SC) area, trabecular meshwork (TM) thickness and length, and scleral spur (SS) length in healthy and primary open-angle glaucoma (POAG) groups.
Methods
Thirty-five eyes of 35 healthy subjects and 23 eyes of 23 patients with POAG were included. The AST, SC area, TM thickness and length, and SS length were measured using swept-source optical coherence tomography. AST was measured at 0 mm (AST0), 1 mm (AST1), 2 mm (AST2), and 3 mm (AST3) from SS. Associations between AST and SC area, TM thickness and length, and SS length were also estimated.
Results
AST0 (728.84 ± 99.33 vs. 657.39 ± 67.02 μm, p < 0.001), AST1 (537.79 ± 79.55 vs. 506.83 ± 57.37 μm, p = 0.038), AST3 (571.09 ± 79.15 vs. 532.13 ± 59.84 μm, p = 0.009), SC area (6304.26 ± 1238.72 vs. 4755.64 ± 1122.71 μm2, p < 0.001), TM thickness (107.21 ± 31.26 vs. 94.51 ± 24.18 μm, p = 0.035), TM length (736.20 ± 141.85 vs. 656.43 ± 127.03 μm, p = 0.004), and SS length (219.89 ± 50.29 vs. 174.54 ± 35.58 μm, p < 0.001) were significantly greater in healthy group than in POAG group. In addition, SC area, TM thickness, and SS length were significantly and positively associated with AST0 in the healthy group, whereas no similar associations were observed in the POAG group.
Conclusions
Compared with the healthy group, AST was significantly thinner in the POAG group, which also had smaller SC and TM dimensions. Moreover, the SC area, TM thickness, and SS length were significantly and positively associated with AST in the healthy group. Thus, AST might play an important role in maintaining TM and SC morphology and further in the pathogenesis of POAG.
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Affiliation(s)
- Xiaoqin Yan
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Mu Li
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Zhiqi Chen
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Xiongwu Zhou
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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15
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Keller KE, Peters DM. Pathogenesis of glaucoma: Extracellular matrix dysfunction in the trabecular meshwork-A review. Clin Exp Ophthalmol 2022; 50:163-182. [PMID: 35037377 DOI: 10.1111/ceo.14027] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 11/19/2021] [Accepted: 11/26/2021] [Indexed: 12/11/2022]
Abstract
The trabecular meshwork regulates aqueous humour outflow from the anterior chamber of the eye. It does this by establishing a tunable outflow resistance, defined by the interplay between cells and their extracellular matrix (ECM) milieu, and the molecular interactions between ECM proteins. During normal tissue homeostasis, the ECM is remodelled and trabecular cell behaviour is modified, permitting increased aqueous fluid outflow to maintain intraocular pressure (IOP) within a relatively narrow physiological pressure. Dysfunction in the normal homeostatic process leads to increased outflow resistance and elevated IOP, which is a primary risk factor for glaucoma. This review delineates some of the changes in the ECM that lead to gross as well as some more subtle changes in the structure and function of the ECM, and their impact on trabecular cell behaviour. These changes are discussed in the context of outflow resistance and glaucoma.
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Affiliation(s)
- Kate E Keller
- Casey Eye Institute, Oregon Health &Science University, Portland, Oregon, USA
| | - Donna M Peters
- Department of Pathology & Laboratory Medicine, University of Wisconsin School of Medicine & Public Health, Madison, Wisconsin, USA
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16
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Relationships between Intraocular Pressure, Effective Filtration Area, and Morphological Changes in the Trabecular Meshwork of Steroid-Induced Ocular Hypertensive Mouse Eyes. Int J Mol Sci 2022; 23:ijms23020854. [PMID: 35055036 PMCID: PMC8775853 DOI: 10.3390/ijms23020854] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/06/2022] [Accepted: 01/10/2022] [Indexed: 02/04/2023] Open
Abstract
We investigated whether an inverse relationship exists between intraocular pressure (IOP) and effective filtration area (EFA) in the trabecular meshwork (TM) in a steroid-induced ocular hypertensive (SIOH) mouse model and the morphological changes associated with the reduction of EFA. C57BL/6 mice (n = 15 per group) received either 0.1% dexamethasone (DEX) or saline eye drops twice daily for five weeks. IOP was measured weekly. Fluorescent tracers were injected into the anterior chamber to label EFA at the endpoint. Injected eyes were fixed and processed for confocal microscopy. EFA in the TM was analyzed. Light and electron microscopy were performed in high- and low-tracer regions of six eyes per group. The mean IOP was ~4 mm Hg higher in DEX-treated than saline-treated control eyes (p < 0.001) at the endpoint. EFA was reduced in DEX-treated eyes compared to controls (p < 0.01) and negatively correlated with IOP (R2 = 0.38, p = 0.002). Reduced thickness of juxtacanalicular tissue (JCT) and increased abnormal extracellular matrix in the JCT were found to be associated with reduced EFA. Our data confirm the inverse relationship between EFA and IOP, suggesting that morphological changes in the JCT contribute to the reduction of EFA, thus elevating IOP in SIOH mouse eyes.
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17
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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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In-vivo imaging of the conventional aqueous outflow system. Curr Opin Ophthalmol 2021; 32:275-279. [PMID: 33653980 DOI: 10.1097/icu.0000000000000751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
PURPOSE OF REVIEW The aim of this study was to provide a comprehensive summary of in-vivo imaging techniques of the aqueous outflow system and discuss its role in improving our understanding of glaucoma pathogenesis and management. RECENT FINDINGS Our understanding of the aqueous outflow system is largely derived from ex-vivo studies. Recent innovations in imaging technology and techniques enable in-vivo evaluation of the conventional outflow system in real-time. Optical coherence tomography allows for noninvasive, high-resolution, volumetric imaging of ocular tissues. Dynamic structural changes have been observed at the trabecular meshwork and Schlemm's canal. In parallel, aqueous angiography using injected tracers show a similar dynamism with variable and pulsatile flow signals. SUMMARY In-vivo imaging enable real-time evaluation of the conventional aqueous outflow pathway. This emerging field shows great promise to expand our understanding of the pathogenesis and treatment of glaucoma.
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Wong VHY, Zhao D, Bui BV, Millar CJ, Nguyen CTO. Increased episcleral venous pressure in a mouse model of circumlimbal suture induced ocular hypertension. Exp Eye Res 2020; 202:108348. [PMID: 33166503 DOI: 10.1016/j.exer.2020.108348] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 10/29/2020] [Accepted: 11/03/2020] [Indexed: 11/30/2022]
Abstract
PURPOSE To investigate changes in aqueous humor dynamics during intraocular pressure (IOP) elevation induced by circumlimbal suture in mice. METHODS Ocular hypertension (OHT) was induced by applying a circumlimbal suture behind the limbus in male adult C57BL6/J mice. In the OHT group, the suture was left in place for an average of 8 weeks (n = 10, OHT group). In the sham control group the suture was cut at 2 days (n = 9, sham group) and in the naïve control group (n = 5) no suture was implanted. IOP was measured at baseline across 3 days, 1 h post-suture implantation, and at the chronic endpoint. Anterior segments were assessed using optical coherence tomography (OCT). Episcleral venous pressure (EVP), total outflow facility (C), uveoscleral outflow (Fu) and aqueous humor flow rate (Fin) were determined using a constant-flow infusion model. RESULTS All aqueous dynamic and chronic IOP outcome measures showed no difference between sham and naïve controls (p > 0.05) and thus these groups were combined into a single control group. IOP was elevated in OHT group compared with controls (p < 0.01). Chronic suture implantation did not change pupil size, anterior chamber depth or iridocorneal angles (p > 0.05). EVP was significantly higher in OHT eyes compared to control eyes (p < 0.01). There was no statistical difference in C, Fu and Fin between groups (p > 0.05). A significant linear correlation was found between IOP and EVP (R2 = 0.35, p = 0.001). CONCLUSIONS Circumlimbal suture implantation in mouse eyes results in chronic IOP elevation without angle closure. Chronic IOP elevation is likely to reflect higher EVP.
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Affiliation(s)
- Vickie H Y Wong
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Da Zhao
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Bang V Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Cameron J Millar
- North Texas Eye Research Institute, Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Christine T O Nguyen
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia.
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Buffault J, Labbé A, Hamard P, Brignole-Baudouin F, Baudouin C. [The trabecular meshwork: Structure, function and clinical implications. A review of the littérature (French translation of the article)]. J Fr Ophtalmol 2020; 43:779-793. [PMID: 32807552 DOI: 10.1016/j.jfo.2020.04.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 04/17/2020] [Accepted: 04/22/2020] [Indexed: 11/26/2022]
Abstract
Glaucoma is a blinding optic neuropathy, the main risk factor for which is increased intraocular pressure (IOP). The trabecular meshwork, located within the iridocorneal angle, is the main pathway for drainage of aqueous humor (AH) out of the eye, and its dysfunction is responsible for the IOP elevation. The trabecular meshwork is a complex, fenestrated, three-dimensional structure composed of trabecular meshwork cells (TMC) interdigitated into a multilayered organization within the extracellular matrix (ECM). The purpose of this literature review is to provide an overview of current understanding of the trabecular meshwork and its pathophysiology in glaucoma. Thus, we will present the main anatomical and cellular bases for the regulation of aqueous humor outflow resistance, the pathophysiological mechanisms involved in trabecular dysfunction in the various types of glaucoma, as well as current and future therapeutic strategies targeting the trabecular meshwork.
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Affiliation(s)
- J Buffault
- Service d'ophtalmologie, centre hospitalier national d'ophtalmologie des Quinze-Vingts, IHU FOReSIGHT, 28, rue de Charenton, 75012 Paris, France.
| | - A Labbé
- Service d'ophtalmologie, centre hospitalier national d'ophtalmologie des Quinze-Vingts, IHU FOReSIGHT, 28, rue de Charenton, 75012 Paris, France; Service d'ophtalmologie, hôpital Ambroise-Paré, AP-HP, 9, avenue Charles-de-Gaulle, 92100 Boulogne-Billancourt, France; Inserm, CNRS, institut de la vision, Sorbonne université, 17, rue Moreau, 75012 Paris, France
| | - P Hamard
- Service d'ophtalmologie, centre hospitalier national d'ophtalmologie des Quinze-Vingts, IHU FOReSIGHT, 28, rue de Charenton, 75012 Paris, France
| | - F Brignole-Baudouin
- Inserm, CNRS, institut de la vision, Sorbonne université, 17, rue Moreau, 75012 Paris, France; Service de biologie médicale, centre hospitalier national d'ophtalmologie des Quinze-Vingts, IHU FOReSIGHT, 28, rue de Charenton, 75012 Paris, France
| | - C Baudouin
- Service d'ophtalmologie, centre hospitalier national d'ophtalmologie des Quinze-Vingts, IHU FOReSIGHT, 28, rue de Charenton, 75012 Paris, France; Service d'ophtalmologie, hôpital Ambroise-Paré, AP-HP, 9, avenue Charles-de-Gaulle, 92100 Boulogne-Billancourt, France; Inserm, CNRS, institut de la vision, Sorbonne université, 17, rue Moreau, 75012 Paris, France
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Bertrand JA, Schicht M, Stamer WD, Baker D, Sherwood JM, Lütjen-Drecoll E, Selwood DL, Overby DR. The β4-Subunit of the Large-Conductance Potassium Ion Channel KCa1.1 Regulates Outflow Facility in Mice. Invest Ophthalmol Vis Sci 2020; 61:41. [PMID: 32203982 PMCID: PMC7401454 DOI: 10.1167/iovs.61.3.41] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Purpose The large-conductance calcium-activated potassium channel KCa1.1 (BKCa, maxi-K) influences aqueous humor outflow facility, but the contribution of auxiliary β-subunits to KCa1.1 activity in the outflow pathway is unknown. Methods Using quantitative polymerase chain reaction, we measured expression of β-subunit genes in anterior segments of C57BL/6J mice (Kcnmb1-4) and in cultured human trabecular meshwork (TM) and Schlemm's canal (SC) cells (KCNMB1-4). We also measured expression of Kcnma1/KCNMA1 that encodes the pore-forming α-subunit. Using confocal immunofluorescence, we visualized the distribution of β4 in the conventional outflow pathway of mice. Using iPerfusion, we measured outflow facility in enucleated mouse eyes in response to 100 or 500 nM iberiotoxin (IbTX; N = 9) or 100 nM martentoxin (MarTX; N = 12). MarTX selectively blocks β4-containing KCa1.1 channels, whereas IbTX blocks KCa1.1 channels that lack β4. Results Kcnmb4 was the most highly expressed β-subunit in mouse conventional outflow tissues, expressed at a level comparable to Kcnma1. β4 was present within the juxtacanalicular TM, appearing to label cellular processes connecting to SC cells. Accordingly, KCNMB4 was the most highly expressed β-subunit in human TM cells, and the sole β-subunit in human SC cells. To dissect functional contribution, MarTX decreased outflow facility by 35% (27%, 42%; mean, 95% confidence interval) relative to vehicle-treated contralateral eyes, whereas IbTX reduced outflow facility by 16% (6%, 25%). Conclusions The β4-subunit regulates KCa1.1 activity in the conventional outflow pathway, significantly influencing outflow function. Targeting β4-containing KCa1.1 channels may be a promising approach to lower intraocular pressure to treat glaucoma.
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Roberts AL, Mavlyutov TA, Perlmutter TE, Curry SM, Harris SL, Chauhan AK, McDowell CM. Fibronectin extra domain A (FN-EDA) elevates intraocular pressure through Toll-like receptor 4 signaling. Sci Rep 2020; 10:9815. [PMID: 32555351 PMCID: PMC7299944 DOI: 10.1038/s41598-020-66756-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 05/27/2020] [Indexed: 02/08/2023] Open
Abstract
Elevated intraocular pressure (IOP) is a major risk factor for the development and progression of primary open angle glaucoma and is due to trabecular meshwork (TM) damage, which leads to impaired aqueous humor outflow. Here, we explore a novel molecular mechanism involved in glaucomatous TM damage. We investigated the role of an endogenous Toll-like receptor 4 (TLR4) ligand, fibronectin-EDA (FN-EDA), in TGFβ2-induced ocular hypertension in mice. We utilized transgenic mouse strains that either constitutively express only FN containing the EDA isoform or contain an EDA-null allele and express only FN lacking EDA, with or without a mutation in Tlr4, in our inducible mouse model of ocular hypertension by injection of Ad5.TGFβ2. IOP was measured over time and eyes accessed by immunohistochemistry for total FN and FN-EDA expression. Constitutively active EDA caused elevated IOP starting at 14 weeks of age. Ad5.TGFβ2 induced ocular hypertension in wildtype C57BL/6J mice and further amplified the IOP in constitutively active EDA mice. TLR4 null and EDA null mice blocked Ad5.TGFβ-induced ocular hypertension. Total FN and FN-EDA isoform expression increased in response to Ad5.TGFβ2. These data suggest that both TLR4 and FN-EDA contribute to TGFβ2 induced ocular hypertension.
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Affiliation(s)
- Amanda L Roberts
- North Texas Eye Research Institute, Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Timur A Mavlyutov
- Department of Ophthalmology and Visual Sciences, McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, United States
| | - Tanisha E Perlmutter
- Department of Ophthalmology and Visual Sciences, McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, United States
| | - Stacy M Curry
- North Texas Eye Research Institute, Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Sherri L Harris
- North Texas Eye Research Institute, Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Anil K Chauhan
- Department of Internal Medicine, University of Iowa, Iowa City, IA, United States
| | - Colleen M McDowell
- Department of Ophthalmology and Visual Sciences, McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, United States.
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The trabecular meshwork: Structure, function and clinical implications. A review of the literature. J Fr Ophtalmol 2020; 43:e217-e230. [PMID: 32561029 DOI: 10.1016/j.jfo.2020.05.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 04/25/2020] [Accepted: 05/27/2020] [Indexed: 02/06/2023]
Abstract
Glaucoma is a blinding optic neuropathy, the main risk factor for which is increased intraocular pressure (IOP). The trabecular meshwork, located within the iridocorneal angle, is the main pathway for drainage of aqueous humor (AH) out of the eye, and its dysfunction is responsible for the IOP elevation. The trabecular meshwork is a complex, fenestrated, three-dimensional structure composed of trabecular meshwork cells (TMC) interdigitated into a multilayered organization within the extracellular matrix (ECM). The purpose of this literature review is to provide an overview of current understanding of the trabecular meshwork and its pathophysiology in glaucoma. Thus, we will present the main anatomical and cellular bases for the regulation of aqueous humor outflow resistance, the pathophysiological mechanisms involved in trabecular dysfunction in the various types of glaucoma, as well as current and future therapeutic strategies targeting the trabecular meshwork.
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Diagnostic power of scleral spur length in primary open-angle glaucoma. Graefes Arch Clin Exp Ophthalmol 2020; 258:1253-1260. [PMID: 32146558 PMCID: PMC7237521 DOI: 10.1007/s00417-020-04637-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 02/17/2020] [Accepted: 02/24/2020] [Indexed: 01/17/2023] Open
Abstract
Purpose To investigate the diagnostic capability of scleral spur length in discriminating eyes with primary open-angle glaucoma (POAG) from healthy eyes. Methods Seventy-eight eyes of 78 patients with POAG and 93 eyes of 93 age-, sex- and axial length-matched healthy subjects were included. The scleral spur length was measured using swept-source optical coherence tomography. Receiver operating characteristic (ROC) curves were derived based on the measurements. Results The scleral spur length was significantly shorter in POAG eyes compared with healthy eyes (Method I, 164.91 ± 23.36 vs. 197.60 ± 25.32 μm; Method II, 145.15 ± 16.59 vs. 166.95 ± 19.31 μm; Method III, 162.33 ± 22.83 vs. 185.12 ± 23.58 μm, respectively; all p < 0.001). The areas under ROC curves were 0.841 (Method I), 0.810 (Method II), and 0.753 (Method III) for the scleral spur length. Moreover, Schlemm’s canal area was significantly associated with the scleral spur length (Method I) in both POAG (β = 0.027; p < 0.001) and healthy (β = 0.016; p = 0.009) groups. Conclusions The scleral spur length had a good discriminating capability between POAG and healthy eyes, and it could be a novel biomarker for POAG evaluation clinically.
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King BJ, Burns SA, Sapoznik KA, Luo T, Gast TJ. High-Resolution, Adaptive Optics Imaging of the Human Trabecular Meshwork In Vivo. Transl Vis Sci Technol 2019; 8:5. [PMID: 31588370 PMCID: PMC6753965 DOI: 10.1167/tvst.8.5.5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 06/24/2019] [Indexed: 12/22/2022] Open
Abstract
Purpose To image the human trabecular meshwork (TM) in vivo using adaptive optics gonioscopy (AOG) with approximately 2-μm lateral resolution. Methods An existing Indiana University adaptive optics scanning laser ophthalmoscope was altered by adding a 12-mm button lens to a clinical gonioscopic lens allowing high-resolution imaging of the human iridocorneal angle. First an anatomic model eye was used to refine the imaging technique and then nine participants (7 controls and 2 participants with pigment dispersion syndrome) were imaged. Results All nine participants were successfully imaged without adverse events. High-resolution imaging of the human TM was achieved allowing for visualization of the TM beams, and presumed endothelial cells. Uveal meshwork beams in controls averaged 25.5 μm (range, 15.2–44.7) in diameter with pores averaging 42.6 μm (range, 22.3–51.4) while the corneoscleral meshwork pores averaged 8.9 μm (range, 7.7–12.1). Differences in appearance of the uveal and corneoscleral meshwork were noted between the two participants with pigment dispersion syndrome and the controls. These included nearly absent spacing between the beams and enlarged endothelial cells with hyperreflective areas. Conclusions AOG allows for near cellular level resolution of the human TM in vivo. This may allow for further understanding of age-related changes that occur as well as provide a deeper understanding of medical and surgical alterations for the treatment of glaucoma. Translational Relevance Further development of this approach may allow for direct measurements at a micometer level in vivo of changes that occur in the human trabecular meshwork with glaucoma and therapeutic interventions.
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Affiliation(s)
- Brett J King
- School of Optometry, Indiana University, Bloomington, IN, USA
| | - Stephen A Burns
- School of Optometry, Indiana University, Bloomington, IN, USA
| | | | - Ting Luo
- School of Optometry, Indiana University, Bloomington, IN, USA
| | - Thomas J Gast
- School of Optometry, Indiana University, Bloomington, IN, USA
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Ficarrotta KR, Bello SA, Mohamed YH, Passaglia CL. Aqueous Humor Dynamics of the Brown-Norway Rat. Invest Ophthalmol Vis Sci 2019; 59:2529-2537. [PMID: 29847660 PMCID: PMC5967599 DOI: 10.1167/iovs.17-22915] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The study aimed to provide a quantitative description of aqueous humor dynamics in healthy rat eyes. Methods One eye of 26 anesthetized adult Brown-Norway rats was cannulated with a needle connected to a perfusion pump and pressure transducer. Pressure-flow data were measured in live and dead eyes by varying pump rate (constant-flow technique) or by modulating pump duty cycle to hold intraocular pressure (IOP) at set levels (modified constant-pressure technique). Data were fit by the Goldmann equation to estimate conventional outflow facility (\begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}C\end{document}) and unconventional outflow rate (\begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}{F_{un}}\end{document}). Parameter estimates were respectively checked by inserting a shunt of similar conductance into the eye and by varying eye hydration methodology. Results Rat IOP averaged 14.6 ± 1.9 mm Hg at rest. Pressure-flow data were repeatable and indistinguishable for the two perfusion techniques, yielding \begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}C\end{document} = 0.023 ± 0.002 μL/min/mm Hg and \begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}{F_{un}}\end{document} = 0.096 ± 0.024 μL/min. \begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}C\end{document} was similar for live and dead eyes and increased upon shunt insertion by an amount equal to shunt conductance, validating measurement accuracy. At 100% humidity \begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}{F_{un}}\end{document} dropped to 0.003 ± 0.030 μL/min. Physiological washout was not observed (−0.35 ± 0.65%/h), and trabecular anatomy looked normal. Conclusions Rat aqueous humor dynamics are intermediate in magnitude compared to those in mice and humans, consistent with species differences in eye size. \begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}C\end{document} does not change with time or death. Evaporation complicates measurement of \begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}{F_{un}}\end{document} even when eyes are not enucleated. Absence of washout is a notable finding seen only in mouse and human eyes to date.
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Affiliation(s)
- Kayla R Ficarrotta
- Chemical and Biomedical Engineering Department, University of South Florida, Tampa, Florida, United States
| | - Simon A Bello
- Electrical Engineering Department, University of South Florida, Tampa, Florida, United States
| | - Youssef H Mohamed
- Chemical and Biomedical Engineering Department, University of South Florida, Tampa, Florida, United States
| | - Christopher L Passaglia
- Chemical and Biomedical Engineering Department, University of South Florida, Tampa, Florida, United States.,Ophthalmology Department, University of South Florida, Tampa, Florida, United States
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27
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Keller KE, Bhattacharya SK, Borrás T, Brunner TM, Chansangpetch S, Clark AF, Dismuke WM, Du Y, Elliott MH, Ethier CR, Faralli JA, Freddo TF, Fuchshofer R, Giovingo M, Gong H, Gonzalez P, Huang A, Johnstone MA, Kaufman PL, Kelley MJ, Knepper PA, Kopczynski CC, Kuchtey JG, Kuchtey RW, Kuehn MH, Lieberman RL, Lin SC, Liton P, Liu Y, Lütjen-Drecoll E, Mao W, Masis-Solano M, McDonnell F, McDowell CM, Overby DR, Pattabiraman PP, Raghunathan VK, Rao PV, Rhee DJ, Chowdhury UR, Russell P, Samples JR, Schwartz D, Stubbs EB, Tamm ER, Tan JC, Toris CB, Torrejon KY, Vranka JA, Wirtz MK, Yorio T, Zhang J, Zode GS, Fautsch MP, Peters DM, Acott TS, Stamer WD. Consensus recommendations for trabecular meshwork cell isolation, characterization and culture. Exp Eye Res 2018; 171:164-173. [PMID: 29526795 PMCID: PMC6042513 DOI: 10.1016/j.exer.2018.03.001] [Citation(s) in RCA: 216] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 03/01/2018] [Indexed: 12/30/2022]
Abstract
Cultured trabecular meshwork (TM) cells are a valuable model system to study the cellular mechanisms involved in the regulation of conventional outflow resistance and thus intraocular pressure; and their dysfunction resulting in ocular hypertension. In this review, we describe the standard procedures used for the isolation of TM cells from several animal species including humans, and the methods used to validate their identity. Having a set of standard practices for TM cells will increase the scientific rigor when used as a model, and enable other researchers to replicate and build upon previous findings.
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Affiliation(s)
| | | | | | | | | | - Abbott F Clark
- University of North Texas Health Sciences Center, United States
| | | | - Yiqin Du
- University of Pittsburgh, United States
| | | | | | | | - Thomas F Freddo
- Massachusetts College of Pharmacy and Health Sciences, United States
| | | | | | | | | | - Alex Huang
- University of California, Los Angeles, United States
| | | | | | | | | | | | | | | | | | | | - Shan C Lin
- University of California, San Francisco, United States
| | | | | | | | - Weiming Mao
- University of North Texas Health Sciences Center, United States
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - James C Tan
- University of Southern California, United States
| | | | | | | | - Mary K Wirtz
- Oregon Health and Science University, United States
| | - Thomas Yorio
- University of North Texas Health Sciences Center, United States
| | - Jie Zhang
- University of California, Los Angeles, United States
| | - Gulab S Zode
- University of North Texas Health Sciences Center, United States
| | - Michael P Fautsch
- Department of Ophthalmology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905, United States.
| | - Donna M Peters
- Department of Pathology & Laboratory Medicine, University of Wisconsin, 1300 University Ave, Madison, WI 53706, United States.
| | - Ted S Acott
- Department of Ophthalmology, Department of Biochemistry & Molecular Biology, Oregon Health and Science University, 3181 SW Sam Jackson Park Rd, Portland, OR 97239, United States.
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, DUMC 3802, Durham, NC 27705, United States.
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28
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Abstract
Immunofluorescent confocal microscopy is a powerful tool for analysis of the morphology and development of vascular and lymphatic tissues. Schlemm's canal (SC) is a large, lymphatic-like vessel in the anterior chamber of the eye, which is essential for aqueous humor drainage required to maintain intraocular pressure and is sensitive to defects in blood and lymphatic vascular signaling pathways. Here, we describe a method to stain and quantify SC area and morphology in enucleated mouse eyes, providing a tool for understanding its development and function in small animal genetic or disease models.
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29
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Keller KE, Bradley JM, Sun YY, Yang YF, Acott TS. Tunneling Nanotubes are Novel Cellular Structures That Communicate Signals Between Trabecular Meshwork Cells. Invest Ophthalmol Vis Sci 2017; 58:5298-5307. [PMID: 29049733 PMCID: PMC5656416 DOI: 10.1167/iovs.17-22732] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Purpose The actin cytoskeleton of trabecular meshwork (TM) cells plays a role in regulating aqueous humor outflow. Many studies have investigated stress fibers, but F-actin also assembles into other supramolecular structures including filopodia. Recently, specialized filopodia called tunneling nanotubes (TNTs) have been described, which communicate molecular signals and organelles directly between cells. Here, we investigate TNT formation by TM cells. Methods Human TM cells were labeled separately with the fluorescent dyes, DiO and DiD, or with mitochondrial dye. Fixed or live TM cells were imaged using confocal microscopy. Image analysis software was used to track fluorescent vesicles and count the number and length of filopodia. The number of fluorescently labeled vesicles transferred between cells was counted in response to specific inhibitors of the actin cytoskeleton. Human TM tissue was stained with phalloidin. Results Live-cell confocal imaging of cultured TM cells showed transfer of fluorescently labeled vesicles and mitochondria via TNTs. In TM tissue, a long (160 μm) actin-rich cell process bridged an intertrabecular space and did not adhere to the substratum. Treatment of TM cells with CK-666, an Arp2/3 inhibitor, significantly decreased the number and length of filopodia, decreased transfer of fluorescently labeled vesicles and induced thick stress fibers compared to vehicle control. Conversely, inhibiting stress fibers using Y27632 increased transfer of vesicles and induced long cell processes. Conclusions Identification of TNTs provides a means by which TM cells can directly communicate with each other over long distances. This may be particularly important to overcome limitations of diffusion-based signaling in the aqueous humor fluid environment.
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Affiliation(s)
- Kate E Keller
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - John M Bradley
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Ying Ying Sun
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Yong-Feng Yang
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Ted S Acott
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
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30
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Kim J, Park DY, Bae H, Park DY, Kim D, Lee CK, Song S, Chung TY, Lim DH, Kubota Y, Hong YK, He Y, Augustin HG, Oliver G, Koh GY. Impaired angiopoietin/Tie2 signaling compromises Schlemm's canal integrity and induces glaucoma. J Clin Invest 2017; 127:3877-3896. [PMID: 28920924 PMCID: PMC5617682 DOI: 10.1172/jci94668] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 07/18/2017] [Indexed: 12/14/2022] Open
Abstract
Primary open-angle glaucoma (POAG) is often caused by elevated intraocular pressure (IOP), which arises due to increased resistance to aqueous humor outflow (AHO). Aqueous humor flows through Schlemm's canal (SC), a lymphatic-like vessel encircling the cornea, and via intercellular spaces of ciliary muscle cells. However, the mechanisms underlying increased AHO resistance are poorly understood. Here, we demonstrate that signaling between angiopoietin (Angpt) and the Angpt receptor Tie2, which is critical for SC formation, is also indispensable for maintaining SC integrity during adulthood. Deletion of Angpt1/Angpt2 or Tie2 in adult mice severely impaired SC integrity and transcytosis, leading to elevated IOP, retinal neuron damage, and impairment of retinal ganglion cell function, all hallmarks of POAG in humans. We found that SC integrity is maintained by interconnected and coordinated functions of Angpt-Tie2 signaling, AHO, and Prox1 activity. These functions diminish in the SC during aging, leading to impaired integrity and transcytosis. Intriguingly, Tie2 reactivation using a Tie2 agonistic antibody rescued the POAG phenotype in Angpt1/Angpt2-deficient mice and rejuvenated the SC in aged mice. These results indicate that the Angpt-Tie2 system is essential for SC integrity. The impairment of this system underlies POAG-associated pathogenesis, supporting the possibility that Tie2 agonists could be a therapeutic option for glaucoma.
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Affiliation(s)
- Jaeryung Kim
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Dae-Young Park
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
- Center for Vascular Research, Institute for Basic Science, Daejeon, Republic of Korea
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Hosung Bae
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Do Young Park
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Dongkyu Kim
- Center for Vascular Research, Institute for Basic Science, Daejeon, Republic of Korea
| | - Choong-kun Lee
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Sukhyun Song
- Center for Vascular Research, Institute for Basic Science, Daejeon, Republic of Korea
| | - Tae-Young Chung
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Dong Hui Lim
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
- Department of Preventive Medicine, Catholic University School of Medicine, Seoul, Republic of Korea
| | - Yoshiaki Kubota
- The Laboratory of Vascular Biology, School of Medicine, Keio University, Tokyo, Japan
| | - Young-Kwon Hong
- Department of Surgery, Department of Biochemistry and Molecular Biology, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Yulong He
- Cyrus Tang Hematology Center, Collaborative Innovation Center of Hematology, Soochow University, Suzhou, China
| | - Hellmut G. Augustin
- Division of Vascular Oncology and Metastasis, German Cancer Research Center Heidelberg (DKFZ-ZMBH Alliance), Heidelberg, Germany
| | - Guillermo Oliver
- Center for Vascular and Developmental Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Gou Young Koh
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
- Center for Vascular Research, Institute for Basic Science, Daejeon, Republic of Korea
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31
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Chang SHL, Lee YS, Wu SC, See LC, Chung CC, Yang ML, Lai CC, Wu WC. Anterior Chamber Angle and Anterior Segment Structure of Eyes in Children With Early Stages of Retinopathy of Prematurity. Am J Ophthalmol 2017; 179:46-54. [PMID: 28450043 DOI: 10.1016/j.ajo.2017.04.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 04/11/2017] [Accepted: 04/12/2017] [Indexed: 11/29/2022]
Abstract
PURPOSE To compare structural differences in the anterior chamber angle (ACA) and related optic components in children with or without retinopathy of prematurity (ROP). DESIGN Prospective cross-sectional study. METHODS Setting: A referred medical center in Taiwan. STUDY POPULATION The patients included preterm children with a history of ROP who had undergone laser therapy. The controls included age-matched healthy full-term children. OBSERVATION PROCEDURE The ACA structures were evaluated using gonioscopy. MAIN OUTCOME MEASURES The angularity of the anterior chamber and associated anatomic changes. RESULTS We examined 54 eyes of 29 preterm children with ROP and 134 eyes of 67 children born at term. The eyes of the ROP children exhibited a narrower ACA, steeper iris curvature, and more anteriorly inserted iris than those of the full-term children (P < .001, P = .002, and P = .08, respectively). The eyes of the ROP children also exhibited steeper corneas, shallower anterior chamber depths, thicker lenses, and higher degrees of refractive errors (all P < .001) than those of the full-term children. The axial lengths did not differ between the 2 groups (P = .15). CONCLUSIONS The eyes of the ROP children presented a narrower ACA and a more anteriorly curved and inserted iris than those of the full-term children. A steeper cornea, shallower anterior chamber, and greater lens thickness were the main structural changes in the anterior segment components of these patients. Further research is needed to investigate the association between these structural changes and the development of certain ocular diseases, such as glaucoma, in these patients.
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Affiliation(s)
- Shirley H L Chang
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou, Taiwan; College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Yung-Sung Lee
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Shiu-Chen Wu
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou, Taiwan; College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Lai-Chu See
- Division of Rheumatology, Allergy and Immunology, Department of Internal Medicine, Chang Gung Memorial Hospital, Linkou, Taiwan; Department of Public Health, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Biostatistics Core Laboratory, Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan
| | - Chia-Chi Chung
- Department of Public Health, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Meng-Lin Yang
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou, Taiwan; College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Chi-Chun Lai
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou, Taiwan; College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Wei-Chi Wu
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou, Taiwan; College of Medicine, Chang Gung University, Taoyuan, Taiwan.
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32
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Liu B, McNally S, Kilpatrick JI, Jarvis SP, O'Brien CJ. Aging and ocular tissue stiffness in glaucoma. Surv Ophthalmol 2017; 63:56-74. [PMID: 28666629 DOI: 10.1016/j.survophthal.2017.06.007] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 06/20/2017] [Accepted: 06/22/2017] [Indexed: 12/27/2022]
Abstract
Glaucoma is a progressive and chronic neurodegenerative disorder characterized by damage to the inner layers of the retina and deformation of the optic nerve head. The degeneration of retinal ganglion cells and their axons results in an irreversible loss of vision and is correlated with increasing age. Extracellular matrix changes related to natural aging generate a stiffer extracellular environment throughout the body. Altered age-associated ocular tissue stiffening plays a major role in a significant number of ophthalmic pathologies. In glaucoma, both the trabecular meshwork and the optic nerve head undergo extensive extracellular matrix remodeling, characterized by fibrotic changes associated with cellular and molecular events (including myofibroblast activation) that drive further tissue fibrosis and stiffening. Here, we review the literature concerning the role of age-related ocular stiffening in the trabecular meshwork, lamina cribrosa, sclera, cornea, retina, and Bruch membrane/choroid and discuss their potential role in glaucoma progression. Because both trabecular meshwork and lamina cribrosa cells are mechanosensitive, we then describe molecular mechanisms underlying tissue stiffening and cell mechanotransduction and how these cellular activities can drive further fibrotic changes within ocular tissues. An improved understanding of the interplay between age-related tissue stiffening and biological responses in the trabecular meshwork and optic nerve head could potentially lead to novel therapeutic strategies for glaucoma treatment.
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Affiliation(s)
- Baiyun Liu
- School of Physics, Conway Institute, University College Dublin, Dublin, Ireland; Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
| | - Sara McNally
- Department of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland
| | - Jason I Kilpatrick
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
| | - Suzanne P Jarvis
- School of Physics, Conway Institute, University College Dublin, Dublin, Ireland; Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
| | - Colm J O'Brien
- Department of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland; School of Medicine and Medical Science, University College Dublin, Dublin, Ireland.
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33
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Hernandez H, Medina-Ortiz WE, Luan T, Clark AF, McDowell CM. Crosstalk Between Transforming Growth Factor Beta-2 and Toll-Like Receptor 4 in the Trabecular Meshwork. Invest Ophthalmol Vis Sci 2017; 58:1811-1823. [PMID: 28346614 PMCID: PMC5374883 DOI: 10.1167/iovs.16-21331] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Purpose The trabecular meshwork (TM) is involved in the outflow of aqueous humor and intraocular pressure (IOP) regulation. Regulation of the extracellular matrix (ECM) by TGFβ2 signaling pathways in the TM has been extensively studied. Recent evidence has implicated toll-like receptor 4 (TLR4) in the regulation of ECM and fibrogenesis in liver, kidney, lung, and skin. Here, we investigated the role of TGFβ2-TLR4 signaling crosstalk in the regulation of the ECM in the TM and ocular hypertension. Methods Cross sections of human donor eyes, primary human TM cells in culture, and dissected mouse TM rings were used to determine Tlr4 expression in the TM. Trabecular meshwork cells in culture were treated with TGFβ2 (5 ng/mL), TLR4 inhibitor (TAK-242, 15 μM), and a TLR4 ligand (cellular fibronectin isoform [cFN]-EDA). A/J (n = 13), AKR/J (n = 7), BALBc/J (n = 8), C3H/HeJ (n = 20), and C3H/HeOuJ (n = 10) mice were injected intravitreally with adenovirus 5 (Ad5).hTGFβ2c226s/c228s in one eye, with the uninjected contralateral eye serving as a control. Conscious IOP measurements were taken using a TonoLab rebound tonometer. Results Toll-like receptor 4 is expressed in the human and mouse TM. Inhibition of TLR4 signaling in the presence of TGFβ2 decreases fibronectin expression. Activation of TLR4 by cFN-EDA in the presence of TGFβ2 further increases fibronectin, laminin, and collagen-1 expression, and TLR4 signaling inhibition blocks this effect. Ad5.hTGFβ2c226s/c228s induces ocular hypertension in wild-type mice but has no effect in Tlr4 mutant (C3H/HeJ) mice. Conclusions These studies identify TGFβ2-TLR4 crosstalk as a novel pathway involved in ECM regulation in the TM and ocular hypertension. These data further explain the complex mechanisms involved in the development of glaucomatous TM damage.
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Affiliation(s)
- Humberto Hernandez
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Wanda E Medina-Ortiz
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Tomi Luan
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Abbot F Clark
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Colleen M McDowell
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
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34
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Moazzeni H, Akbari MT, Yazdani S, Elahi E. Expression of CXCL6 and BBS5 that may be glaucoma relevant genes is regulated by PITX2. Gene 2016; 593:76-83. [PMID: 27520585 DOI: 10.1016/j.gene.2016.08.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 07/31/2016] [Accepted: 08/08/2016] [Indexed: 12/26/2022]
Abstract
The transcription factor PITX2 is implicated in glaucoma pathology. In an earlier study we had used microarray analysis to identify genes in the trabecular meshwork (TM) that are affected by knock down of PITX2. Here, those studies were pursued to identify genes that are direct targets of PITX2 and that may be relevant to glaucoma. Initially, bioinformatics tools were used to select among the genes that had been affected by PITX2 knock down those that have PITX2 binding sites and that may be involved in glaucoma related functions. Subsequently, the effect of PITX2 was tested using the dual luciferase assay in four cell cultures including two primary TM cultures co-transfected with vectors containing promoter fragments of six candidate genes upstream of a luciferase gene and a vector that expressed PITX2. Finally, the effect of PITX2 on endogenous expression of two genes was assessed by over expression and knock down of PITX2 in TM cells. Thirty four genes were found to contain PITX2 binding sites in their putative promoter regions, and 16 were found to be associated with TM-specific and/or glaucoma associated functions. Results of dual luciferase assays confirmed that two of six genes tested were directly targeted by PITX2. The two genes were CXCL6 (chemokine (C-X-C motif) ligand 6) and BBS5 (Bardet-Biedl syndrome 5). Over expression and knock down of PITX2 showed that this transcription factor affects endogenous expression of these two genes in TM cells. CXCL6 encodes a pro-inflammatory cytokine, and many studies have suggested that cytokines and other immune system functions are involved in glaucoma pathogenesis. BBS5 is a member of the BBS family of genes that affect ciliary functions, and ciliary bodies in the anterior chamber of the eye produce the aqueous fluid that affects intraocular pressure. Immune related functions and intraocular pressure are both important components of glaucoma pathology. The role of PITX2 in glaucoma may be mediated partly by regulating the expression of CXCL6 and BBS5 and thus affecting immune functions and intraocular pressure.
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Affiliation(s)
- Hamidreza Moazzeni
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, P.O. Box. 14115-331, Tehran, Iran
| | - Mohammad Taghi Akbari
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, P.O. Box. 14115-331, Tehran, Iran.
| | - Shahin Yazdani
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Elahe Elahi
- School of Biology, College of Science, University of Tehran, Tehran, Iran; Department of Biotechnology, College of Science, University of Tehran, Tehran, Iran.
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35
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Pervan CL. Smad-independent TGF-β2 signaling pathways in human trabecular meshwork cells. Exp Eye Res 2016; 158:137-145. [PMID: 27453344 DOI: 10.1016/j.exer.2016.07.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 07/06/2016] [Accepted: 07/18/2016] [Indexed: 10/24/2022]
Abstract
Aberrant expression and signaling of Transforming Growth Factor (TGF)-β is strongly associated with development of elevated intraocular pressure (IOP) and primary open-angle glaucoma (POAG). In cells of the trabecular meshwork, a key component of the conventional outflow pathway, TGF-β is well-known to promote expression of multiple ocular hypertensive mediators, including genes associated with fibrosis as well as cellular contractility. These effects are mediated by induction of canonical (Smad) as well as non-canonical (MAPK, Rho GTPase) signaling cascades. In the present review, we will highlight the non-canonical, Smad-independent signaling pathways activated by TGF-β2 in human TM cells, as well as the genes known to be induced by non-canonical TGF-β2 signaling.
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Affiliation(s)
- Cynthia L Pervan
- Research Service (151), Department of Veterans Affairs, Edward Hines Jr. VA Hospital, Hines, IL, 60141, USA; Department of Ophthalmology, Loyola University Chicago, Maywood, IL, USA.
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36
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Chen L, Zhao Y, Zhang H. Comparative Anatomy of the Trabecular Meshwork, the Optic Nerve Head and the Inner Retina in Rodent and Primate Models Used for Glaucoma Research. Vision (Basel) 2016; 1:vision1010004. [PMID: 31740629 PMCID: PMC6848998 DOI: 10.3390/vision1010004] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 06/26/2016] [Accepted: 07/08/2016] [Indexed: 12/13/2022] Open
Abstract
Glaucoma is a heterogeneous group of ocular disorders with a multi-faceted etiology. Although numerous studies on glaucoma using different animal models have been published, it is unwise to simply generalize the results of one model to all glaucomatous situations because of the differences in the anatomy and morphology of animal eyes in comparison with humans’. In this review, we highlight the differences in the trabecular meshwork (TM) tissue, lamina cribrosa (LC) region, optic nerve head (ONH) and the inner layer of the retina in mice, rats and monkeys. In comparison with humans, non-human primates show TM, retina and ONH that are anatomically almost identical. The rat model shows many similarities in the aqueous outflow pathway compared to humans. The mouse ONH lacks collagenous LC, and this finding is observed across different mouse strains. The tissue structure of the ONH in rodents is similar to that in humans, although the blood supply shows differences. The number of cells in the ganglion layer depends on the rodent strain. Despite some differences from humans, rodents are a good choice for studying different types of glaucoma, and the modeling method should be selected based on the experimental needs and the hypothesis being tested.
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Affiliation(s)
| | | | - Hong Zhang
- Correspondence: ; Tel.: +86-139-7167-9079; Fax: +86-027-8366-3688
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37
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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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38
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Dautriche CN, Tian Y, Xie Y, Sharfstein ST. A Closer Look at Schlemm's Canal Cell Physiology: Implications for Biomimetics. J Funct Biomater 2015; 6:963-85. [PMID: 26402712 PMCID: PMC4598687 DOI: 10.3390/jfb6030963] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 08/10/2015] [Accepted: 09/06/2015] [Indexed: 12/13/2022] Open
Abstract
Among ocular pathologies, glaucoma is the second leading cause of progressive vision loss, expected to affect 80 million people worldwide by 2020. A primary cause of glaucoma appears to be damage to the conventional outflow tract. Conventional outflow tissues, a composite of the trabecular meshwork and the Schlemm's canal, regulate and maintain homeostatic responses to intraocular pressure. In glaucoma, filtration of aqueous humor into the Schlemm's canal is hindered, leading to an increase in intraocular pressure and subsequent damage to the optic nerve, with progressive vision loss. The Schlemm's canal encompasses a unique endothelium. Recent advances in culturing and manipulating Schlemm's canal cells have elucidated several aspects of their physiology, including ultrastructure, cell-specific marker expression, and biomechanical properties. This review highlights these advances and discusses implications for engineering a 3D, biomimetic, in vitro model of the Schlemm's canal endothelium to further advance glaucoma research, including drug testing and gene therapy screening.
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Affiliation(s)
- Cula N Dautriche
- State University of New York (SUNY) Polytechnic Institute, Colleges of Nanoscale Science and Engineering, 257 Fuller Road, Albany, NY 12203, USA.
| | - Yangzi Tian
- State University of New York (SUNY) Polytechnic Institute, Colleges of Nanoscale Science and Engineering, 257 Fuller Road, Albany, NY 12203, USA.
| | - Yubing Xie
- State University of New York (SUNY) Polytechnic Institute, Colleges of Nanoscale Science and Engineering, 257 Fuller Road, Albany, NY 12203, USA.
| | - Susan T Sharfstein
- State University of New York (SUNY) Polytechnic Institute, Colleges of Nanoscale Science and Engineering, 257 Fuller Road, Albany, NY 12203, 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: 256] [Impact Index Per Article: 28.4] [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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Bhartiya S, Ichhpujani P, Shaarawy T. Surgery on the Trabecular Meshwork: Histopathological Evidence. J Curr Glaucoma Pract 2015; 9:51-61. [PMID: 26997835 PMCID: PMC4750027 DOI: 10.5005/jp-journals-10008-1184] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 05/02/2015] [Indexed: 11/23/2022] Open
Abstract
Juxtacanalicular (JXT) trabecular meshwork and endothelial lining of Schlemm's canal have been cited as the loci of aqueous outflow resistance, both in a normal as well as a glaucomatous eye. In this review, we attempt to understand the currently available surgical modalities in light of the available histopathological evidence, regarding localization of outflow resistance. How to cite this article: Bhartiya S, Ichhpujani P, Shaarawy T. Surgery on the Trabecular Meshwork: Histopathological Evidence. J Curr Glaucoma Pract 2015;9(2):51-61.
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Affiliation(s)
- Shibal Bhartiya
- Senior Consultant, Glaucoma Facility, Fortis Memorial Research Institute, Gurgaon Haryana, India
| | - Parul Ichhpujani
- Associate Professor, Department of Ophthalmology, Glaucoma Facility, Government Medical College and Hospital, Chandigarh, India
| | - Tarek Shaarawy
- Head, Glaucoma Sector, Geneva University Hospital, Rue Gabrielle-Perret-Gentil 4, 1205 Geneva, Switzerland
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Swain DL, Ho J, Lai J, Gong H. Shorter scleral spur in eyes with primary open-angle glaucoma. Invest Ophthalmol Vis Sci 2015; 56:1638-48. [PMID: 25670488 DOI: 10.1167/iovs.14-15593] [Citation(s) in RCA: 20] [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 We determined whether the scleral spur is shorter in primary open-angle glaucoma (POAG) eyes compared to age-matched normal eyes and whether the collapse of Schlemm's canal (SC) is more prevalent in eyes with a shorter scleral spur. METHODS The anterior segments of normal (n = 20) and POAG eyes (n = 20) were fixed and processed for light microscopy. The scleral spur length, ratio of posterior trabecular meshwork (TM) insertion into the scleral spur to the posterior TM height, and the percentage of SC collapse were measured. Analysis using an existing mathematical model was conducted to estimate the distances that the scleral spur theoretically would move in vivo and to determine if these distances would be sufficient to keep SC open in POAG compared to normal eyes. RESULTS The mean scleral spur length was significantly shorter in POAG eyes compared to normal eyes (P < 0.0001). A higher mean percentage of SC collapse was found in POAG eyes than in normal eyes (P < 0.0001). Estimated posterior movement of scleral spur in POAG eyes was less than sufficient to prevent the collapse of SC. A significant negative correlation was found between the posterior scleral spur movement and percent collapse of SC (P < 0.0001). CONCLUSIONS A shorter scleral spur found in POAG eyes was associated with a higher percent of SC collapse. Our data suggest that a shorter scleral spur may be a risk factor in the development of POAG by being insufficient to hold SC open.
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Affiliation(s)
- David L Swain
- Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Joseph Ho
- Department of Ophthalmology, Tufts-New England Eye Center, Boston, Massachusetts, United States
| | - Julia Lai
- Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Haiyan Gong
- Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts, United States
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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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Kurtenbach S, Kurtenbach S, Zoidl G. Emerging functions of pannexin 1 in the eye. Front Cell Neurosci 2014; 8:263. [PMID: 25309318 PMCID: PMC4163987 DOI: 10.3389/fncel.2014.00263] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 08/14/2014] [Indexed: 01/23/2023] Open
Abstract
Pannexin 1 (Panx1) is a high-conductance, voltage-gated channel protein found in vertebrates. Panx1 is widely expressed in many organs and tissues, including sensory systems. In the eye, Panx1 is expressed in major divisions including the retina, lens and cornea. Panx1 is found in different neuronal and non-neuronal cell types. The channel is mechanosensitive and responds to changes in extracellular ATP, intracellular calcium, pH, or ROS/nitric oxide. Since Panx1 channels operate at the crossroad of major signaling pathways, physiological functions in important autocrine and paracrine feedback signaling mechanisms were hypothesized. This review starts with describing in depth the initial Panx1 expression and localization studies fostering functional studies that uncovered distinct roles in processing visual information in subsets of neurons in the rodent and fish retina. Panx1 is expressed along the entire anatomical axis from optical nerve to retina and cornea in glia, epithelial and endothelial cells as well as in neurons. The expression and diverse localizations throughout the eye points towards versatile functions of Panx1 in neuronal and non-neuronal cells, implicating Panx1 in the crosstalk between immune and neural cells, pressure related pathological conditions like glaucoma, wound repair or neuronal cell death caused by ischemia. Summarizing the literature on Panx1 in the eye highlights the diversity of emerging Panx1 channel functions in health and disease.
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Affiliation(s)
- Sarah Kurtenbach
- Department of Psychology, Faculty of Health, York University Toronto, ON, Canada
| | - Stefan Kurtenbach
- Department of Psychology, Faculty of Health, York University Toronto, ON, Canada
| | - Georg Zoidl
- Department of Psychology, Faculty of Health, York University Toronto, ON, Canada ; Department of Biology, Faculty of Science, York University Toronto, ON, Canada
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Aspelund A, Tammela T, Antila S, Nurmi H, Leppänen VM, Zarkada G, Stanczuk L, Francois M, Mäkinen T, Saharinen P, Immonen I, Alitalo K. The Schlemm's canal is a VEGF-C/VEGFR-3-responsive lymphatic-like vessel. J Clin Invest 2014; 124:3975-86. [PMID: 25061878 PMCID: PMC4153703 DOI: 10.1172/jci75395] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 05/30/2014] [Indexed: 12/21/2022] Open
Abstract
In glaucoma, aqueous outflow into the Schlemm's canal (SC) is obstructed. Despite striking structural and functional similarities with the lymphatic vascular system, it is unknown whether the SC is a blood or lymphatic vessel. Here, we demonstrated the expression of lymphatic endothelial cell markers by the SC in murine and zebrafish models as well as in human eye tissue. The initial stages of SC development involved induction of the transcription factor PROX1 and the lymphangiogenic receptor tyrosine kinase VEGFR-3 in venous endothelial cells in postnatal mice. Using gene deletion and function-blocking antibodies in mice, we determined that the lymphangiogenic growth factor VEGF-C and its receptor, VEGFR-3, are essential for SC development. Delivery of VEGF-C into the adult eye resulted in sprouting, proliferation, and growth of SC endothelial cells, whereas VEGF-A obliterated the aqueous outflow system. Furthermore, a single injection of recombinant VEGF-C induced SC growth and was associated with trend toward a sustained decrease in intraocular pressure in adult mice. These results reveal the evolutionary conservation of the lymphatic-like phenotype of the SC, implicate VEGF-C and VEGFR-3 as critical regulators of SC lymphangiogenesis, and provide a basis for further studies on therapeutic manipulation of the SC with VEGF-C in glaucoma treatment.
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Edwards G, Aribindi K, Guerra Y, Lee RK, Bhattacharya SK. Phospholipid profiles of control and glaucomatous human aqueous humor. Biochimie 2014; 101:232-47. [PMID: 24561385 PMCID: PMC3995849 DOI: 10.1016/j.biochi.2014.01.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 01/31/2014] [Indexed: 10/25/2022]
Abstract
To compare phospholipid (phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine and phosphatidylinositol) profiles of human control and glaucomatous aqueous humor (AQH). AQH samples were procured during surgery from human POAG and control subjects (n = 15 each). Samples were used following institutional review board approved protocols and adhering to the tenets of the Declaration of Helsinki. Lipid extraction was performed using a modification of the Bligh and Dyer method, protein concentrations were determined using the Bradford's method, and select samples were confirmed with Densitometry of PHAST gels. Lipids were identified and subjected to ratiometric quantification using a TSQ Quantum Access Max triple quadrupole mass spectrometer utilizing precursor ion scan (PIS) or neutral ion loss scan (NLS) using appropriate class specific lipid standards in a two step quantification process. The comparative profiles of phosphatidylcholines, phosphatidylserines, phosphatidylethanolamines and phosphatidylinositols between control and glaucomatous AQH showed several species common between them. A number of unique lipids in all four phospholipid classes were also identified in control eyes that were absent in glaucomatous eyes and vice versa. A number of phospholipids were found to be uniquely present in control, but absent in glaucomatous AQH and vice versa. Compared with a previous study of control and POAG red blood cells, a number of these phospholipids are absent locally (AQH).
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Affiliation(s)
- Genea Edwards
- Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, FL 33136, USA
| | - Katyayini Aribindi
- Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, FL 33136, USA
| | - Yenifer Guerra
- Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, FL 33136, USA
| | - Richard K Lee
- Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, FL 33136, USA
| | - Sanjoy K Bhattacharya
- Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, FL 33136, USA.
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Teixeira LBC, Zhao Y, Dubielzig RR, Sorenson CM, Sheibani N. Ultrastructural abnormalities of the trabecular meshwork extracellular matrix in Cyp1b1-deficient mice. Vet Pathol 2014; 52:397-403. [PMID: 24879660 DOI: 10.1177/0300985814535613] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Cytochrome P450 1B1 (CYP1B1) is highly expressed in human and murine ocular tissues during development. Mutations in this gene are implicated in the development of primary congenital glaucoma (PCG) in humans. Mice deficient in Cyp1b1 (Cyp1b1(-/-) ) present developmental abnormalities similar to human primary congenital glaucoma. The present work describes the ultrastructural morphology of the iridocorneal angle of 21 eyes from 1-week-old to 8-month-old Cyp1b1(-/-) mice. Morphometric and semiquantitative analysis of the data revealed that 3-week-old Cyp1b1(-/-) mice present a significantly (P < .005) decreased amount of trabecular meshwork (TM) collagen and higher TM endothelial cell and collagen lesion scores (P < .005) than age-matched controls. Collagen loss and lesion scores were progressively increased in older animals, with 8-month-old animals presenting severe atrophy of the TM. Our findings advance the understanding of the effects of CYP1B1 mutations in TM development and primary congenital glaucoma, as well as suggest a link between TM morphologic alterations and increased intraocular pressure.
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Affiliation(s)
- L B C Teixeira
- Department of Pathobiological Sciences, School of Veterinary Medicine, Madison, WI, USA McPherson Eye Research Institute, University of Wisconsin, Madison, WI, USA
| | - Y Zhao
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, WI, USA
| | - R R Dubielzig
- Department of Pathobiological Sciences, School of Veterinary Medicine, Madison, WI, USA McPherson Eye Research Institute, University of Wisconsin, Madison, WI, USA
| | - C M Sorenson
- McPherson Eye Research Institute, University of Wisconsin, Madison, WI, USA Department of Pediatrics, University of Wisconsin, Madison, WI, USA
| | - N Sheibani
- McPherson Eye Research Institute, University of Wisconsin, Madison, WI, USA Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, WI, USA
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Overby DR, Bertrand J, Schicht M, Paulsen F, Stamer WD, Lütjen-Drecoll E. The structure of the trabecular meshwork, its connections to the ciliary muscle, and the effect of pilocarpine on outflow facility in mice. Invest Ophthalmol Vis Sci 2014; 55:3727-36. [PMID: 24833737 DOI: 10.1167/iovs.13-13699] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To determine the connections between the ciliary muscle (CM), trabecular meshwork (TM), and Schlemm's canal (SC) and their innervations that allows CM contraction (by pilocarpine) to influence conventional outflow in mice. METHODS Sequential sections and whole mounts of murine corneoscleral angles were stained for elastin, α-smooth muscle actin (αSMA), vesicular acetylcholine transporter (VAChT), neuronal nitric oxide synthase (nNOS), vasoactive intestinal peptide (VIP), and tyrosine hydroxylase (TH). Elastic (EL) fibers between the CM, TM, and SC were examined in ultrathin, sequential sections from different planes. The effect of pilocarpine (100 μM) on conventional outflow facility was measured by perfusion of enucleated mouse eyes. RESULTS The mouse TM contains a three-dimensional (3D) net of EL fibers connecting the inner wall of SC to the cornea anteriorly, the ciliary body (CB) internally and the choroid and CM posteriorly. The CM bifurcates near the posterior TM, extending outer tendons to the juxtacanalicular tissue and inner wall of SC and internal connections to the lamellated TM and CB. Ciliary muscle and lamellated TM cells stain with αSMA and are innervated by VAChT-containing nerve fibers, without TH, VIP, or nNOS. Pilocarpine doubled outflow facility. CONCLUSIONS Mouse eyes resemble primate eyes not only by their well developed SC and TM, but also by their 3D EL net tethering together the TM and SC inner wall and by the tendinous insertion of the CM into this net. The increase in outflow facility following cholinergic stimulation in mice, as in primates, supports using mice for studies of aqueous humor dynamics and glaucoma.
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Affiliation(s)
- Darryl R Overby
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Jacques Bertrand
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Martin Schicht
- Department of Anatomy II, University of Erlangen-Nürnberg, Germany
| | | | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
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Dua HS, Faraj LA, Branch MJ, Yeung AM, Elalfy MS, Said DG, Gray T, Lowe J. The collagen matrix of the human trabecular meshwork is an extension of the novel pre-Descemet's layer (Dua's layer). Br J Ophthalmol 2014; 98:691-7. [PMID: 24532799 DOI: 10.1136/bjophthalmol-2013-304593] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND The trabecular meshwork (TM) located at the angle of the anterior chamber of the eye contributes to aqueous drainage. A novel layer in the posterior part of the human cornea has recently been reported (the pre-Descemet's layer (Dua's layer (PDL)). We examined the peripheral part of this layer in relation to the origin of the TM. METHODS The PDL and TM of 19 human donor eyes and one exenterated sample were studied. Samples were examined by light and electron microscopy (EM) for tissue architecture and by immunohistology for four matricellular proteins, five collagen types and CD34. RESULTS EM revealed that beams of collagen emerged from the periphery of PDL on the anterior surface of the Descemet's membrane and divided and subdivided to continue as the beams of the TM. Long-spacing collagen was seen in the PDL and TM. Trabecular cells (CD34-ve) associated with basement membrane were seen in the peripheral part of the PDL and corresponded to the start of the separation of the collagen lamellae of PDL. Collagen VI was present continuously in PDL and extended into the TM. Matricellular proteins were seen predominantly in the TM with only laminin extending into the periphery of PDL. CONCLUSIONS This study provides an insight into the origins of the collagen core of the TM as an extension of the PDL of the cornea. This finding adds to the knowledge base of the TM and cornea and has the potential to impact future research into the TM and glaucoma.
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Affiliation(s)
- Harminder S Dua
- The Larry A Donoso Laboratory, Academic Ophthalmology, University of Nottingham, UK
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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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Challa P, Arnold JJ. Rho-kinase inhibitors offer a new approach in the treatment of glaucoma. Expert Opin Investig Drugs 2013; 23:81-95. [PMID: 24094075 DOI: 10.1517/13543784.2013.840288] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
INTRODUCTION Primary open-angle glaucoma (POAG) is a leading cause for worldwide blindness and is characterized by progressive optic nerve damage. The etiology of POAG is unknown, but elevated intraocular pressure (IOP) and advanced age have been identified as risk factors. IOP reduction is the only known treatment for glaucoma. Recently, drugs that inhibit rho-associated protein kinase (ROCK) have been studied in animals and people for their ability to lower IOP and potentially treat POAG. ROCK inhibitors lower IOP through a trabecular mechanism and may represent a new therapeutic paradigm for the treatment of POAG. AREAS COVERED Exploring the place that ROCK inhibitors may occupy in our treatment of POAG requires a thorough understanding of pathophysiology and treatment. This article summarizes current research on the incidence, proposed etiologies and mechanisms of action for this drug class. ROCK inhibitor research is presented and considered in light of the current standard of pharmacologic care. EXPERT OPINION ROCK inhibitors alter the cell shape and extracellular matrix (ECM) of the trabecular meshwork. Preclinical studies demonstrate that these drugs have the potential to become a new therapy for glaucoma. However, ROCK inhibitors can affect multiple cell types, and their utility can be proven only after clinical studies in patients.
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Affiliation(s)
- Pratap Challa
- Duke University, Ophthalmology , 2351 Erwin Road, Durham 27710 , USA
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