1
|
Schnabellehner S, Kraft M, Schoofs H, Ortsäter H, Mäkinen T. Penile cavernous sinusoids are Prox1-positive hybrid vessels. VASCULAR BIOLOGY (BRISTOL, ENGLAND) 2024; 6:e230014. [PMID: 38051669 PMCID: PMC10831540 DOI: 10.1530/vb-23-0014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 12/05/2023] [Indexed: 12/07/2023]
Abstract
Endothelial cells (ECs) of blood and lymphatic vessels have distinct identity markers that define their specialized functions. Recently, hybrid vasculatures with both blood and lymphatic vessel-specific features have been discovered in multiple tissues. Here, we identify the penile cavernous sinusoidal vessels (pc-Ss) as a new hybrid vascular bed expressing key lymphatic EC identity genes Prox1, Vegfr3,and Lyve1. Using single-cell transcriptome data of human corpus cavernosum tissue, we found heterogeneity within pc-S endothelia and observed distinct transcriptional alterations related to inflammatory processes in hybrid ECs in erectile dysfunction associated with diabetes. Molecular, ultrastructural, and functional studies further established hybrid identity of pc-Ss in mouse, and revealed their morphological adaptations and ability to perform lymphatic-like function in draining high-molecular-weight tracers. Interestingly, we found that inhibition of the key lymphangiogenic growth factor VEGF-C did not block the development of pc-Ss in mice, distinguishing them from other lymphatic and hybrid vessels analyzed so far. Our findings provide a detailed molecular characterization of hybrid pc-Ss and pave the way for the identification of molecular targets for therapies in conditions of dysregulated penile vasculature, including erectile dysfunction.
Collapse
Affiliation(s)
- Sarah Schnabellehner
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Marle Kraft
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Hans Schoofs
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Henrik Ortsäter
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Taija Mäkinen
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| |
Collapse
|
2
|
Schmitt HM, Hake KM, Perkumas KM, Lê BM, Suarez MF, De Ieso ML, Rahman RS, Johnson WM, Gomez-Caraballo M, Ashley-Koch AE, Hauser MA, Stamer WD. Lysyl oxidase-like 1-antisense 1 (LOXL1-AS1) lncRNA differentially regulates gene and protein expression, signaling and morphology of human ocular cells. Hum Mol Genet 2023; 32:3053-3062. [PMID: 37540217 PMCID: PMC10586201 DOI: 10.1093/hmg/ddad128] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 06/19/2023] [Accepted: 08/01/2023] [Indexed: 08/05/2023] Open
Abstract
Pseudoexfoliation glaucoma (PEXG) is characterized by dysregulated extracellular matrix (ECM) homeostasis that disrupts conventional outflow function and increases intraocular pressure (IOP). Prolonged IOP elevation results in optic nerve head damage and vision loss. Uniquely, PEXG is a form of open angle glaucoma that has variable penetrance, is difficult to treat and does not respond well to common IOP-lowering pharmaceuticals. Therefore, understanding modulators of disease severity will aid in targeted therapies for PEXG. Genome-wide association studies have identified polymorphisms in the long non-coding RNA lysyl oxidase-like 1-antisense 1 (LOXL1-AS1) as a risk factor for PEXG. Risk alleles, oxidative stress and mechanical stretch all alter LOXL1-AS1 expression. As a long non-coding RNA, LOXL1-AS1 binds hnRNPL and regulates global gene expression. In this study, we focus on the role of LOXL1-AS1 in the ocular cells (trabecular meshwork and Schlemm's canal) that regulate IOP. We show that selective knockdown of LOXL1-AS1 leads to cell-type-specific changes in gene expression, ECM homeostasis, signaling and morphology. These results implicate LOXL1-AS1 as a modulator of cellular homeostasis, altering cell contractility and ECM turnover, both of which are well-known contributors to PEXG. These findings support LOXL1-AS1 as a key target for modifying the disease.
Collapse
Affiliation(s)
- Heather M Schmitt
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA
- Department of Medicine, Duke University, Durham, NC 27710, USA
| | - Kristyn M Hake
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA
- Department of Medicine, Duke University, Durham, NC 27710, USA
| | | | - Brandon M Lê
- Department of Medicine, Duke University, Durham, NC 27710, USA
| | - Maria F Suarez
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA
- Department of Medicine, Duke University, Durham, NC 27710, USA
| | | | - Rashad S Rahman
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA
| | - William M Johnson
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA
- Department of Medicine, Duke University, Durham, NC 27710, USA
| | | | | | - Michael A Hauser
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA
- Department of Medicine, Duke University, Durham, NC 27710, USA
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA
| |
Collapse
|
3
|
Shim MS, Dixon A, Nettesheim A, Perkumas KM, Stamer WD, Sun Y, Liton PB. Shear stress induces autophagy in Schlemm's canal cells via primary cilia-mediated SMAD2/3 signaling pathway. AUTOPHAGY REPORTS 2023; 2:2236519. [PMID: 37637387 PMCID: PMC10448710 DOI: 10.1080/27694127.2023.2236519] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 06/05/2023] [Accepted: 06/13/2023] [Indexed: 08/29/2023]
Abstract
The Schlemm's canal (SC) is a circular, lymphatic-like vessel located at the limbus of the eye that participates in the regulation of aqueous humor drainage to control intraocular pressure (IOP). Circumferential flow of aqueous humor within the SC lumen generates shear stress, which regulates SC cell behaviour. Using biochemical analysis and real-time live cell imaging techniques, we have investigated the activation of autophagy in SC cells by shear stress. We report, for the first time, the primary cilium (PC)-dependent activation of autophagy in SC cells in response to shear stress. Moreover, we identified PC-dependent shear stress-induced autophagy to be positively regulated by phosphorylation of SMAD2 in its linker and C-terminal regions. Additionally, SMAD2/3 signaling was found to transcriptionally activate LC3B, ATG5 and ATG7 in SC cells. Intriguingly, concomitant to SMAD2-dependent activation of autophagy, we also report here the activation of mTOR pathway, a classical autophagy inhibitor, in SC cells by shear stress. mTOR activation was found to also be dependent on the PC. Moreover, pharmacological inhibition of class I PI3K increased phosphorylation of SMAD2 at the linker and activated autophagy. Together, our data indicates an interplay between PI3K and SMAD2/3 signaling pathways in the regulation of PC-dependent shear stress-induced autophagy in SC cells.
Collapse
Affiliation(s)
- Myoung Sup Shim
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
| | - Angela Dixon
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
| | - April Nettesheim
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
| | - Kristin M. Perkumas
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
| | - W. Daniel Stamer
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
| | - Yang Sun
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Paloma B. Liton
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
| |
Collapse
|
4
|
Julian TH, Girach Z, Sanderson E, Guo H, Yu J, Cooper-Knock J, Black GC, Sergouniotis PI. Causal factors in primary open angle glaucoma: a phenome-wide Mendelian randomisation study. Sci Rep 2023; 13:9984. [PMID: 37340071 DOI: 10.1038/s41598-023-37144-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Accepted: 06/16/2023] [Indexed: 06/22/2023] Open
Abstract
Primary open angle glaucoma (POAG) is a chronic, adult-onset optic neuropathy associated with characteristic optic disc and/or visual field changes. With a view to identifying modifiable risk factors for this common neurodegenerative condition, we performed a 'phenome-wide' univariable Mendelian randomisation (MR) study that involved analysing the relationship between 9661 traits and POAG. Utilised analytical approaches included weighted mode based estimation, the weighted median method, the MR Egger method and the inverse variance weighted (IVW) approach. Eleven traits related to POAG risk were identified including: serum levels of the angiopoietin-1 receptor (OR [odds ratio] = 1.11, IVW p = 2.34E-06) and the cadherin 5 protein (OR = 1.06, IVW p = 1.31E-06); intraocular pressure (OR = 2.46-3.79, IVW p = 8.94E-44-3.00E-27); diabetes (OR = 5.17, beta = 1.64, IVW p = 9.68E-04); and waist circumference (OR = 0.79, IVW p = 1.66E-05). Future research focussing on the effects of adiposity, cadherin 5 and angiopoietin-1 receptor on POAG development and progression is expected to provide key insights that might inform the provision of lifestyle modification advice and/or the development of novel therapies.
Collapse
Affiliation(s)
- Thomas H Julian
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
- Manchester Royal Eye Hospital, Manchester University NHS Foundation Trust, Manchester, UK
| | - Zain Girach
- Sheffield Medical School, University of Sheffield, Sheffield, UK
| | - Eleanor Sanderson
- MRC Integrative Epidemiology Unit, Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Hui Guo
- Centre for Biostatistics, Division of Population Health, Health Services Research and Primary Care, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Jonathan Yu
- Manchester Royal Eye Hospital, Manchester University NHS Foundation Trust, Manchester, UK
| | - Johnathan Cooper-Knock
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, UK
| | - Graeme C Black
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
- Manchester Centre for Genomic Medicine, Saint Mary's Hospital, Manchester University NHS Foundation Trust, Manchester, UK
| | - Panagiotis I Sergouniotis
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.
- Manchester Royal Eye Hospital, Manchester University NHS Foundation Trust, Manchester, UK.
- Manchester Centre for Genomic Medicine, Saint Mary's Hospital, Manchester University NHS Foundation Trust, Manchester, UK.
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Cambridge, UK.
| |
Collapse
|
5
|
Mavlyutov TA, Kuhn MS, Bilal SE, De Ieso ML, Chauhan AK, Stamer WD, McDowell CM. Decreased outflow facility and Schlemm's canal defects in a mouse model of glaucoma. Exp Eye Res 2022; 225:109249. [PMID: 36152913 PMCID: PMC9722577 DOI: 10.1016/j.exer.2022.109249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/24/2022] [Accepted: 09/12/2022] [Indexed: 12/29/2022]
Abstract
Previously we identified B6.EDA+/+ mice as a novel mouse model that presents with elevated IOP and trabecular meshwork damage. Here, we expand on our previous findings by measuring aqueous humor outflow facility and analyzing the integrity of the inner wall of Schlemm's canal. As expected, intraocular pressure (IOP) was increased, and outflow facility was decreased compared to C57BL/6J controls. B6.EDA+/+ mice had significantly increased expression of the adherens junction protein, VE-cadherin by the inner wall endothelium of Schlemm's canal. These data suggest that in addition to trabecular meshwork damage, there are changes in Schlemm's canal in B6.EDA+/+ mice that lead to aqueous outflow dysfunction and ocular hypertension.
Collapse
Affiliation(s)
- Timur A Mavlyutov
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, 53575, USA
| | - Megan S Kuhn
- Duke Eye Center, Duke University, Durham, NC, USA
| | - Samer E Bilal
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, 53575, USA
| | | | - Anil K Chauhan
- Department of Internal Medicine, Division of Hematology/Oncology, University of Iowa, Iowa City, IA, USA
| | | | - Colleen M McDowell
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, 53575, USA.
| |
Collapse
|
6
|
Li H, Singh A, Perkumas KM, Stamer WD, Ganapathy PS, Herberg S. YAP/TAZ Mediate TGFβ2-Induced Schlemm's Canal Cell Dysfunction. Invest Ophthalmol Vis Sci 2022; 63:15. [PMID: 36350617 PMCID: PMC9652721 DOI: 10.1167/iovs.63.12.15] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 10/18/2022] [Indexed: 11/11/2022] Open
Abstract
Purpose Elevated transforming growth factor beta2 (TGFβ2) levels in the aqueous humor have been linked to glaucomatous outflow tissue dysfunction. Potential mediators of dysfunction are the transcriptional coactivators, Yes-associated protein (YAP) and transcriptional coactivator with PDZ binding motif (TAZ). However, the molecular underpinnings of YAP/TAZ modulation in Schlemm's canal (SC) cells under glaucomatous conditions are not well understood. Here, we investigate how TGFβ2 regulates YAP/TAZ activity in human SC (HSC) cells using biomimetic extracellular matrix hydrogels, and examine whether pharmacological YAP/TAZ inhibition would attenuate TGFβ2-induced HSC cell dysfunction. Methods Primary HSC cells were seeded atop photo-cross-linked extracellular matrix hydrogels, made of collagen type I, elastin-like polypeptide and hyaluronic acid, or encapsulated within the hydrogels. HSC cells were induced with TGFβ2 in the absence or presence of concurrent actin destabilization or pharmacological YAP/TAZ inhibition. Changes in actin cytoskeletal organization, YAP/TAZ activity, extracellular matrix production, phospho-myosin light chain levels, and hydrogel contraction were assessed. Results TGFβ2 significantly increased YAP/TAZ nuclear localization in HSC cells, which was prevented by either filamentous-actin relaxation or depolymerization. Pharmacological YAP/TAZ inhibition using verteporfin without light stimulation decreased fibronectin expression and actomyosin cytoskeletal rearrangement in HSC cells induced by TGFβ2. Similarly, verteporfin significantly attenuated TGFβ2-induced HSC cell-encapsulated hydrogel contraction. Conclusions Our data provide evidence for a pathologic role of aberrant YAP/TAZ signaling in HSC cells under simulated glaucomatous conditions and suggest that pharmacological YAP/TAZ inhibition has promising potential to improve outflow tissue dysfunction.
Collapse
Affiliation(s)
- Haiyan Li
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, New York, United States
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York, United States
| | - Ayushi Singh
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, New York, United States
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York, United States
| | - Kristin M. Perkumas
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, North Carolina, United States
| | - W. Daniel Stamer
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, North Carolina, United States
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
| | - Preethi S. Ganapathy
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, New York, United States
- Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, New York, United States
- BioInspired Institute, Syracuse University, Syracuse, New York, United States
| | - Samuel Herberg
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, New York, United States
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York, United States
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, United States
- BioInspired Institute, Syracuse University, Syracuse, New York, United States
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York, United States
| |
Collapse
|
7
|
VIP Stabilizes the Cytoskeleton of Schlemm's Canal Endothelia via Reducing Caspase-3 Mediated ZO-1 Endolysosomal Degradation. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:9397960. [PMID: 34552687 PMCID: PMC8452417 DOI: 10.1155/2021/9397960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 07/05/2021] [Accepted: 08/23/2021] [Indexed: 11/17/2022]
Abstract
Objectives In glaucomatous eyes, the main aqueous humor (AH) outflow pathway is damaged by accumulated oxidative stress arising from the microenvironment, vascular dysregulation, and aging, which results in increased outflow resistance and ocular hypertension. Schlemm's canal (SC) serves as the final filtration barrier of the main AH outflow pathway. The present study is aimed at investigating the possible regulation of vasoactive intestinal peptide (VIP) on the cytoskeleton by stabilizing ZO-1 in SC. Methods Model of chronic ocular hypertension (COH) induced by episcleral venous cauterization was treated with topical VIP. The ultrastructure of junctions, ZO-1 levels, and permeability of the SC inner wall to FITC-dextran (70 kDa) were detected in the COH models. The F-actin distribution, F/G-actin ratio, and ZO-1 degradation pathway in human umbilical vein endothelial cells (HUVECs) and HEK 293 cells were investigated. Results ZO-1 in the outer wall of the SC was less than that in the inner wall. COH elicited junction disruption, ZO-1 reduction, and increased permeability of the SC inner wall to FITC-dextran in rats. ZO-1 plays an essential role in maintaining the F/G-actin ratio and F-actin distribution. VIP treatment attenuated the downregulation of ZO-1 associated with COH or H2O2-induced oxidative damage. In H2O2-stimulated HUVECs, the caspase-3 inhibitor prevents ZO-1 disruption. Caspase-3 activation promoted endolysosomal degradation of ZO-1. Furthermore, a decrease in caspase-3 activation and cytoskeleton redistribution was demonstrated in VIP + H2O2-treated cells. The knockdown of ZO-1 or the overexpression of caspase-3 blocked the effect of VIP on the cytoskeleton. Conclusion This study provides insights into the role of VIP in stabilizing the interaction between the actin cytoskeleton and cell junctions and may provide a promising targeted strategy for glaucoma treatment.
Collapse
|
8
|
Fibrotic Changes to Schlemm's Canal Endothelial Cells in Glaucoma. Int J Mol Sci 2021; 22:ijms22179446. [PMID: 34502356 PMCID: PMC8431431 DOI: 10.3390/ijms22179446] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 08/27/2021] [Accepted: 08/29/2021] [Indexed: 12/21/2022] Open
Abstract
Previous studies have shown that glaucomatous Schlemm’s canal endothelial cells (gSCECs) are stiffer and associated with reduced porosity and increased extracellular matrix (ECM) material compared to SCECs from healthy individuals. We hypothesised that Schlemm’s canal (SC) cell stiffening was a function of fibrotic changes occurring at the inner wall of SC in glaucoma. This study was performed in primary cell cultures isolated from the SC lumen of human donor eyes. RNA and protein quantification of both fibrotic and endothelial cell markers was carried out on both healthy and gSCECs. Functional assays to assess cell density, size, migration, proliferation, and mitochondrial function of these cells were also carried out. Indeed, we found that gSCECs deviate from typical endothelial cell characteristics and exhibit a more fibrotic phenotype. For example, gSCECs expressed significantly higher protein levels of the fibrotic markers α-SMA, collagen I-α1, and fibronectin, as well as significantly increased protein expression of TGFβ-2, the main driver of fibrosis, compared to healthy SCECs. Interestingly, we observed a significant increase in protein expression of endothelial marker VE-cadherin in gSCECs, compared to healthy SCECs. gSCECs also appeared to be significantly larger, and surprisingly proliferate and migrate at a significantly higher rate, as well as showing significantly reduced mitochondrial activity, compared to healthy SCECs.
Collapse
|
9
|
Vincent MP, Stack T, Vahabikashi A, Li G, Perkumas KM, Ren R, Gong H, Stamer WD, Johnson M, Scott EA. Surface Engineering of FLT4-Targeted Nanocarriers Enhances Cell-Softening Glaucoma Therapy. ACS APPLIED MATERIALS & INTERFACES 2021; 13:32823-32836. [PMID: 34232612 PMCID: PMC9131393 DOI: 10.1021/acsami.1c09294] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Primary open-angle glaucoma is associated with elevated intraocular pressure (IOP) that damages the optic nerve and leads to gradual vision loss. Several agents that reduce the stiffness of pressure-regulating Schlemm's canal (SC) endothelial cells, in the conventional outflow pathway of the eye, lower IOP in glaucoma patients and are approved for clinical use. However, poor drug penetration and uncontrolled biodistribution limit their efficacy and produce local adverse effects. Compared to other ocular endothelia, FLT4/VEGFR3 is expressed at elevated levels by SC endothelial cells and can be exploited for targeted drug delivery. Here, we validate FLT4 receptors as clinically relevant targets on SC cells from glaucomatous human donors and engineer polymeric self-assembled nanocarriers displaying lipid-anchored targeting ligands that optimally engage this receptor. Targeting constructs were synthesized as lipid-PEGx-peptide, differing in the number of PEG spacer units (x), and were embedded in micelles. We present a novel proteolysis assay for quantifying ligand accessibility that we employ to design and optimize our FLT4-targeting strategy for glaucoma nanotherapy. Peptide accessibility to proteases correlated with receptor-mediated targeting enhancements. Increasing the accessibility of FLT4-binding peptides enhanced nanocarrier uptake by SC cells while simultaneously decreasing the uptake by off-target vascular endothelial cells. Using a paired longitudinal IOP study in vivo, we show that this enhanced targeting of SC cells translates to IOP reductions that are sustained for a significantly longer time as compared to controls. Confocal microscopy of murine anterior segment tissue confirmed nanocarrier localization to SC within 1 h after intracameral administration. This work demonstrates that steric effects between surface-displayed ligands and PEG coronas significantly impact the targeting performance of synthetic nanocarriers across multiple biological scales. Minimizing the obstruction of modular targeting ligands by PEG measurably improved the efficacy of glaucoma nanotherapy and is an important consideration for engineering PEGylated nanocarriers for targeted drug delivery.
Collapse
Affiliation(s)
- Michael P Vincent
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Trevor Stack
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Amir Vahabikashi
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Cell and Developmental Biology, Northwestern University, Chicago, Illinois 60611, United States
| | - Guorong Li
- Department of Ophthalmology, Duke University, Durham, North Carolina 27710, United States
| | - Kristin M Perkumas
- Department of Ophthalmology, Duke University, Durham, North Carolina 27710, United States
| | - Ruiyi Ren
- Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts 02118, United States
| | - Haiyan Gong
- Department of Ophthalmology, Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts 02118, United States
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina 27710, United States
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
| | - Mark Johnson
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Ophthalmology, Northwestern University, Chicago, Illinois 60611, United States
- Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Evan A Scott
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Simpson Querrey Institute, Northwestern University, Chicago, Illinois 60611, USA
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, Illinois 60611, United States
| |
Collapse
|
10
|
Wang Y, Wang W, Yang X, Chen W, Yang X, Pan X, Xu P, Zhu W, Han Y, Chen X. ITGA8 positive cells in the conventional outflow tissue exhibit Schlemm's canal endothelial cell properties. Life Sci 2021; 278:119564. [PMID: 33961857 DOI: 10.1016/j.lfs.2021.119564] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 04/19/2021] [Accepted: 04/23/2021] [Indexed: 11/17/2022]
Abstract
AIMS Elevated intraocular pressure is primarily induced by the increased resistance of conventional outflow of aqueous humor. Dysfunction of the juxtacanalicular region of trabecular meshwork (TM) and Schlemm's canal (SC) endothelium, as the main conventional outflow tissue, have been implicated as the major reasons for the increased resistance. Integrins are widespread in these tissues, especially alpha8 integrin (ITGA8). We aim to investigate the properties of cells expressing ITGA8 in the conventional outflow tissue. MAIN METHODS Fluorescence in situ hybridization (FISH) and immunofluorescence (IF) were performed to detect the mRNA and protein levels of ITGA8 in human conventional outflow tissue. ITGA8-positive cells were isolated from the cultured human TM cells through a magnetic bead-based approach. Flow Cytometry was used to determine the purification efficiency. The expressions of TM and SC biomarkers and dexamethasone-induced myocilin secretion capacity of ITGA8-positive cells was assessed by Real-time PCR, IF and Western blot. A gel contraction assay was performed to evaluate contractility of ITGA8-positive cells after endothelin 1 treatment. KEY FINDINGS ITGA8 was found with robust expression near the inner wall of SC endothelium. After purification, the proportion of ITGA8-positive cells were increased by about 10%. ITGA8-positive cells were identified with the properties as SC endothelial cells, such as more robust expressions of SC biomarkers, less dexamethasone-inducible myocilin expression, and stronger contractility. SIGNIFICANCE This study demonstrated that cells expressing ITGA8 in SC region possess more properties as SC endothelial cells. Our data implicate a crucial role of ITGA8 in aqueous humor (AH) outflow resistance regulation.
Collapse
Affiliation(s)
- Yanan Wang
- School of Basic Medicine, Qingdao University, Qingdao 266021, China; Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao 266021, China
| | - Wenyan Wang
- School of Basic Medicine, Qingdao University, Qingdao 266021, China; Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao 266021, China
| | - Xuejiao Yang
- Affiliated Hospital of Qingdao University, Qingdao 266003, China
| | - Wenshi Chen
- Affiliated Hospital of Qingdao University, Qingdao 266003, China
| | - Xian Yang
- Affiliated Hospital of Qingdao University, Qingdao 266003, China
| | - Xiaojing Pan
- Qingdao Eye Hospital, Shandong Eye Institute, Shandong Academy of Medical Sciences, Qingdao 266071, China
| | - Peilong Xu
- State Key Laboratory of Bio-Fibers and Eco-Textiles, Qingdao University, Qingdao 266071, China
| | - Wei Zhu
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao 266021, China; Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beihang, University & Capital Medical University, Beijing 100730, China
| | - Yantao Han
- School of Basic Medicine, Qingdao University, Qingdao 266021, China.
| | - Xuehong Chen
- School of Basic Medicine, Qingdao University, Qingdao 266021, China.
| |
Collapse
|
11
|
Roy Chowdhury U, Bahler CK, Hann CR, Holman BH, Fautsch MP. Isolation and characterization of novel primary cells from the human distal outflow pathway. Sci Rep 2021; 11:4034. [PMID: 33597641 PMCID: PMC7890058 DOI: 10.1038/s41598-021-83558-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 02/01/2021] [Indexed: 12/01/2022] Open
Abstract
Ocular hypertension occurs due to increased resistance to aqueous humor removal through the conventional outflow pathway. Unlike the proximal region of the conventional outflow pathway, the distal region has not been well studied, mostly due to lack of model systems. Here we describe isolation and characterization of human primary vascular distal outflow pathway (VDOP) cells from the distal region of the conventional outflow pathway. Tissue from the distal region was isolated from human corneo-scleral rims, digested with collagenase type I (100 U/ml) and placed on gelatin coated plates to allow cellular growth in Dulbecco's Modified Eagle's Medium (low glucose) containing fetal bovine serum and antibiotic/antimycotic. VDOP cells showed consistent proliferation for up to 7 passages, retained endothelial-like nature of the parent tissues and showed a unique marker phenotype of Lectin+VEGFR2-CD34-NG2- that was distinct from neighboring trabecular meshwork (Lectin+VEGFR2-CD34-NG2+) and Schlemm's canal (Lectin+VEGFR2+CD34+NG2+) cells. Dexamethasone treated VDOP cells did not express myocilin and did not form cross-linked actin networks, in contrast to trabecular meshwork cells. These data show that VDOP cells are unique to the distal outflow region and can be used as a viable in vitro model system to understand the biology of the distal outflow pathway and intraocular pressure regulation.
Collapse
Affiliation(s)
- Uttio Roy Chowdhury
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
| | - Cindy K Bahler
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Cheryl R Hann
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Bradley H Holman
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Michael P Fautsch
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| |
Collapse
|
12
|
Li G, Nottebaum AF, Brigell M, Navarro ID, Ipe U, Mishra S, Gomez-Caraballo M, Schmitt H, Soldo B, Pakola S, Withers B, Peters KG, Vestweber D, Stamer WD. A Small Molecule Inhibitor of VE-PTP Activates Tie2 in Schlemm's Canal Increasing Outflow Facility and Reducing Intraocular Pressure. Invest Ophthalmol Vis Sci 2020; 61:12. [PMID: 33315051 PMCID: PMC7735951 DOI: 10.1167/iovs.61.14.12] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 11/09/2020] [Indexed: 12/11/2022] Open
Abstract
Purpose Tyrosine kinase with immunoglobulin-like and EGF-like domains 2 (Tie2) activation in Schlemm's canal (SC) endothelium is required for the maintenance of IOP, making the angiopoietin/Tie2 pathway a target for new and potentially disease modifying glaucoma therapies. The goal of the present study was to examine the effects of a Tie2 activator, AKB-9778, on IOP and outflow function. Methods AKB-9778 effects on IOP was evaluated in humans, rabbits, and mice. Localization studies of vascular endothelial protein tyrosine phosphatase (VE-PTP), the target of AKB-9778 and a negative regulator of Tie2, were performed in human and mouse eyes. Mechanistic studies were carried out in mice, monitoring AKB-9778 effects on outflow facility, Tie2 phosphorylation, and filtration area of SC. Results AKB-9778 lowered IOP in patients treated subcutaneously for diabetic eye disease. In addition to efficacious, dose-dependent IOP lowering in rabbit eyes, topical ocular AKB-9778 increased Tie2 activation in SC endothelium, reduced IOP, and increased outflow facility in mouse eyes. VE-PTP was localized to SC endothelial cells in human and mouse eyes. Mechanistically, AKB-9778 increased the filtration area of SC for aqueous humor efflux in both wild type and in Tie2+/- mice. Conclusions This is the first report of IOP lowering in humans with a Tie2 activator and functional demonstration of its action in remodeling SC to increase outflow facility and lower IOP in fully developed mice. Based on these studies, a phase II clinical trial is in progress to advance topical ocular AKB-9778 as a first in class, Tie2 activator for treatment for ocular hypertension and glaucoma.
Collapse
Affiliation(s)
- Guorong Li
- Department of Ophthalmology, Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
| | | | | | - Iris D. Navarro
- Department of Ophthalmology, Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
| | - Ute Ipe
- Max Planck Institute of Molecular Biomedicine, Muenster, Germany
| | - Sarthak Mishra
- Max Planck Institute of Molecular Biomedicine, Muenster, Germany
| | - Maria Gomez-Caraballo
- Department of Ophthalmology, Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
| | - Heather Schmitt
- Department of Ophthalmology, Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
| | - Brandi Soldo
- Aerpio Pharmaceuticals, Inc., Cincinnati, Ohio, United States
| | - Steve Pakola
- Aerpio Pharmaceuticals, Inc., Cincinnati, Ohio, United States
| | - Barbara Withers
- Aerpio Pharmaceuticals, Inc., Cincinnati, Ohio, United States
| | - Kevin G. Peters
- Aerpio Pharmaceuticals, Inc., Cincinnati, Ohio, United States
| | | | - W. Daniel Stamer
- Department of Ophthalmology, Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
| |
Collapse
|
13
|
Reina-Torres E, De Ieso ML, Pasquale LR, Madekurozwa M, van Batenburg-Sherwood J, Overby DR, Stamer WD. The vital role for nitric oxide in intraocular pressure homeostasis. Prog Retin Eye Res 2020; 83:100922. [PMID: 33253900 DOI: 10.1016/j.preteyeres.2020.100922] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 11/13/2020] [Accepted: 11/23/2020] [Indexed: 02/07/2023]
Abstract
Catalyzed by endothelial nitric oxide (NO) synthase (eNOS) activity, NO is a gaseous signaling molecule maintaining endothelial and cardiovascular homeostasis. Principally, NO regulates the contractility of vascular smooth muscle cells and permeability of endothelial cells in response to either biochemical or biomechanical cues. In the conventional outflow pathway of the eye, the smooth muscle-like trabecular meshwork (TM) cells and Schlemm's canal (SC) endothelium control aqueous humor outflow resistance, and therefore intraocular pressure (IOP). The mechanisms by which outflow resistance is regulated are complicated, but NO appears to be a key player as enhancement or inhibition of NO signaling dramatically affects outflow function; and polymorphisms in NOS3, the gene that encodes eNOS modifies the relation between various environmental exposures and glaucoma. Based upon a comprehensive review of past foundational studies, we present a model whereby NO controls a feedback signaling loop in the conventional outflow pathway that is sensitive to changes in IOP and its oscillations. Thus, upon IOP elevation, the outflow pathway tissues distend, and the SC lumen narrows resulting in increased SC endothelial shear stress and stretch. In response, SC cells upregulate the production of NO, relaxing neighboring TM cells and increasing permeability of SC's inner wall. These IOP-dependent changes in the outflow pathway tissues reduce the resistance to aqueous humor drainage and lower IOP, which, in turn, diminishes the biomechanical signaling on SC. Similar to cardiovascular pathogenesis, dysregulation of the eNOS/NO system leads to dysfunctional outflow regulation and ocular hypertension, eventually resulting in primary open-angle glaucoma.
Collapse
Affiliation(s)
| | | | - Louis R Pasquale
- Eye and Vision Research Institute of New York Eye and Ear Infirmary at Mount Sinai, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | | | | | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, UK.
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC, USA.
| |
Collapse
|
14
|
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.
Collapse
|
15
|
Cai J, Perkumas K, Stamer WD, Liu Y. An In Vitro Bovine Cellular Model for Human Schlemm's Canal Endothelial Cells and Their Response to TGFβ Treatment. Transl Vis Sci Technol 2020; 9:32. [PMID: 32832237 PMCID: PMC7414733 DOI: 10.1167/tvst.9.7.32] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 05/17/2020] [Indexed: 12/12/2022] Open
Abstract
Purpose Due to the limited availability of primary human Schlemm's canal (SC) endothelial cells, we aimed to develop an in vitro cellular model using the angular aqueous plexus (AAP) cells from bovine eyes. Methods We harvested a mixture of cells from the trabecular meshwork region including AAP loops from multiple donors, followed by puromycin treatment and immunostaining of Von Willebrand factor and vascular endothelial (VE)-cadherin to confirm identity. Previously identified differentially expressed genes in glaucomatous SC cells were examined in non-glaucomatous SC cells (n = 3) under 0% or 15% equibiaxial strain for 24 hours using droplet digital polymerase chain reaction (ddPCR) and analyzed using the Ingenuity Pathway Analysis (IPA) software application to identify upstream regulators. To compare the cellular responses to candidate regulators of these mechanoresponsive genes, AAP and human SC cells (n = 3) were treated with 5 or 10 ng/mL transforming growth factor beta-2 (TGFβ2) for 24 or 48 hours, followed with expression profiling using real-time PCR or ddPCR. Results We found that the isolated AAP cells displayed uniform cobblestone-like morphology and positive expression of two endothelial markers. In stretched SC cells, nine glaucoma-related genes were upregulated, and IPA implicated TGFβ as a potential upstream regulator. The effects of TGFβ2 treatment were similar for both AAP and SC cells in a dose- and time-dependent manner, activating TGFBR1 and SMAD2, inhibiting BMP4, and altering expression of three glaucoma-related genes (DCN,EZR, and CYP1B1). Conclusions Bovine AAP cells may serve as an alternative cellular model of human SC cells. Translational Relevance These AAP cells may be used to study the functional pathways related to the outflow facility.
Collapse
Affiliation(s)
- Jingwen Cai
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | | | - W. Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC, USA
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Yutao Liu
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
- James & Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
- Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA, USA
| |
Collapse
|
16
|
Tian YI, Zhang X, Torrejon K, Danias J, Gindina S, Nayyar A, Du Y, Xie Y. A bioengineering approach to Schlemm's canal-like stem cell differentiation for in vitro glaucoma drug screening. Acta Biomater 2020; 105:203-213. [PMID: 31982588 DOI: 10.1016/j.actbio.2020.01.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 12/30/2022]
Abstract
Human Schlemm's canal (HSC) cells are critical for understanding outflow physiology and glaucoma etiology. However, primary donor cells frequently used in research are difficult to isolate. HSC cells exhibit both vascular and lymphatic markers. Human adipose-derived stem cells (ADSCs) represent a potential source of HSC due to their capacity to differentiate into both vascular and lymphatic endothelial cells, via VEGF-A and VEGF-C. Shear stress plays a critical role in maintaining HSC integrity, function, and PROX1 expression. Additionally, the human trabecular meshwork (HTM) microenvironment could provide cues for HSC-like differentiation. We hypothesize that subjecting ADSCs to VEGF-A or VEGF-C, shear stress, and co-culture with HTM cells could provide biological, mechanical, and cellular cues necessary for HSC-like differentiation. To test this hypothesis, effects of VEGF-A, VEGF-C, and shear stress on ADSC differentiation were examined and compared to primary HSC cells in terms of cell morphology, and HSC marker expression using qPCR, immunoblotting, and immunocytochemistry analysis. Furthermore, the effect of co-culture with HTM cells on porous scaffolds on ADSC differentiation was studied. Treatment with VEGF-C under shear stress is effective in differentiating ADSCs into PROX1-expressing HSC-like cells. Co-culture with HTM cells on porous scaffolds leads to HTM/ADSC-derived HSC-like constructs that regulate through-flow and respond as expected to dexamethasone. STATEMENT OF SIGNIFICANCE: We successfully generated human Schlemm's canal (HSC) like cells from adipocyte-derived stem cells induced by biochemical and biomechanical cues as well as bioengineered human trabecular meshwork (HTM) on micropatterned, porous SU8 scaffolds. These stem cell-derived HSC-like cells co-cultured with HTM cells on SU8 scaffolds can regulate through-flow, and in particular, are responsive to steroid treatment as expected. These findings show that ADSC-derived HSC-like cells have the potential to recreate the ocular outflow pathway for in vitro glaucoma drug screening. To the best of our knowledge, it is the very first time to demonstrate derivation of Schlemm's canal-like cells from stem cells. It provides an important alternative source to primary Schlemm's canal cells that are very difficult to be isolated and cultured from human donors.
Collapse
Affiliation(s)
- Yangzi Isabel Tian
- College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, 257 Fuller Road, Albany, NY 12203, USA
| | - Xulang Zhang
- College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, 257 Fuller Road, Albany, NY 12203, USA
| | - Karen Torrejon
- Glauconix Biosciences, Inc., 251 Fuller Road, Albany, NY 12203, USA
| | - John Danias
- SUNY Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY 11203, USA
| | - Sofya Gindina
- SUNY Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY 11203, USA
| | - Ashima Nayyar
- SUNY Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY 11203, USA
| | - Yiqin Du
- University of Pittsburg School of Medicine, 203 Lothrop Street, Pittsburgh, PA 15213, USA
| | - Yubing Xie
- College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, 257 Fuller Road, Albany, NY 12203, USA.
| |
Collapse
|
17
|
Pawlak JB, Caron KM. Lymphatic Programing and Specialization in Hybrid Vessels. Front Physiol 2020; 11:114. [PMID: 32153423 PMCID: PMC7044189 DOI: 10.3389/fphys.2020.00114] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 01/31/2020] [Indexed: 12/14/2022] Open
Abstract
Building on a large body of existing blood vascular research, advances in lymphatic research have helped kindle broader investigations into vascular diversity and endothelial plasticity. While the endothelium of blood and lymphatic vessels can be distinguished by a variety of molecular markers, the endothelia of uniquely diverse vascular beds can possess distinctly heterogeneous or hybrid expression patterns. These expression patterns can then provide further insight on the development of these vessels and how they perform their specialized function. In this review we examine five highly specialized hybrid vessel beds that adopt partial lymphatic programing for their specialized vascular functions: the high endothelial venules of secondary lymphoid organs, the liver sinusoid, the Schlemm’s canal of the eye, the renal ascending vasa recta, and the remodeled placental spiral artery. We summarize the morphology and endothelial expression pattern of these vessels, compare them to each other, and interrogate their specialized functions within the broader blood and lymphatic vascular systems.
Collapse
Affiliation(s)
- John B Pawlak
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Kathleen M Caron
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| |
Collapse
|
18
|
Caglayan M, Kocamıs SI, Sarac O, Tatli Dogan H, Kosekahya P, Ayan M, Cagil N. Investigation of Heme Oxygenase 2 Enzyme Protein Expression in Keratoconus and Normal Human Corneal Epithelium: An Immunohistochemical Study. Curr Eye Res 2018; 44:25-29. [DOI: 10.1080/02713683.2018.1521980] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Mehtap Caglayan
- Department of Ophthalmology, Mardin State Hospital, Mardin, Turkey
| | | | - Ozge Sarac
- Department of Ophthalmology, Yildirim Beyazit University, Ankara, Turkey
| | | | - Pinar Kosekahya
- Department of Ophthalmology, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey
| | - Murat Ayan
- Department of Ophthalmology, Yenimahalle State Hospital, Ankara, Turkey
| | - Nurullah Cagil
- Department of Ophthalmology, Yildirim Beyazit University, Ankara, Turkey
| |
Collapse
|
19
|
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.
Collapse
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.
| |
Collapse
|
20
|
Zhang Y, Yang Q, Guo F, Chen X, Xie L. Link between neurodegeneration and trabecular meshwork injury in glaucomatous patients. BMC Ophthalmol 2017; 17:223. [PMID: 29183303 PMCID: PMC5706159 DOI: 10.1186/s12886-017-0623-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 11/20/2017] [Indexed: 11/29/2022] Open
Abstract
Background Glaucoma is classified as a neurodegenerative disease. However, the biomarkers of neurodegeneration in the aqueous humour of primary open angle glaucoma (POAG) eyes have not been quantitatively examined yet. In this study, levels of neurodegeneration-related cytokines in the aqueous humour of POAG eyes were measured and compared with those of non-glaucoma (senile cataract) control eyes. Methods This cross-sectional study included 24 patients (24 eyes) with POAG and 22 patients (22 eyes) with cataract. Aqueous humour samples were collected before the commencement of phacoemulsification surgery. The concentrations of brain-derived neurotrophic factor (BDNF), cathepsin D, myeloperoxidase (MPO), soluble intercellular adhesion molecule-1 (sICAM-1), soluble neural cell adhesion molecule (sNCAM), soluble vascular cell adhesion molecule-1 (sVCAM-1), and plasminogen activator inhibitor-1 (PAI-1) were measured using the Luminex suspension array technique. The clinical characteristics of the patients were also obtained for correlation analysis. Results Compared with the cataract group, the levels of cathepsin D (P < 0.001), sNCAM (P < 0.001) and sVCAM-1 (P = 0.007) were significantly higher in the aqueous humour samples from POAG. The levels of BDNF, sICAM-1, MPO and PAI-1 did not differ among the groups. Mean deviation (MD) values measured by the Humphrey Visual Field Analyzer were significantly associated with levels of cathepsin D (P < 0.001; ρ= − 0.668), sICAM-1 (P = 0.003; ρ= − 0.579), sVCAM-1(P < 0.001; ρ= − 0.695), and PAI-1 (P = 0.007; ρ= − 0.533). The cytokines showed a positive correlation among each other (P < 0.0083). Conclusion These data suggest that POAG patients had elevated levels of multiple biomarkers of neurodegeneration in the aqueous humour, and these elevated biomarkers may be related to trabecular meshwork injury. Trial registration This study was registered in the Chinese Clinical Trial Registry (ChiCTR-OOC-16008516) on May 22, 2016.
Collapse
Affiliation(s)
- Yong Zhang
- Department of Ophthalmology, Daping Hospital & Research Institute of Surgery, Third Military Medical University, No.10, Changjiang Branch Road, Chongqing, 400042, People's Republic of China
| | - Qinmei Yang
- Department of Ophthalmology, Daping Hospital & Research Institute of Surgery, Third Military Medical University, No.10, Changjiang Branch Road, Chongqing, 400042, People's Republic of China
| | - Feng Guo
- Department of Ophthalmology, Daping Hospital & Research Institute of Surgery, Third Military Medical University, No.10, Changjiang Branch Road, Chongqing, 400042, People's Republic of China
| | - Xia Chen
- Department of Ophthalmology, Daping Hospital & Research Institute of Surgery, Third Military Medical University, No.10, Changjiang Branch Road, Chongqing, 400042, People's Republic of China
| | - Lin Xie
- Department of Ophthalmology, Daping Hospital & Research Institute of Surgery, Third Military Medical University, No.10, Changjiang Branch Road, Chongqing, 400042, People's Republic of China.
| |
Collapse
|
21
|
Bracha P, Moore NA, Ciulla TA, WuDunn D, Cantor LB. The acute and chronic effects of intravitreal anti-vascular endothelial growth factor injections on intraocular pressure: A review. Surv Ophthalmol 2017; 63:281-295. [PMID: 28882597 DOI: 10.1016/j.survophthal.2017.08.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Revised: 08/27/2017] [Accepted: 08/28/2017] [Indexed: 01/18/2023]
Abstract
The acute and chronic effects of repeated intravitreal antivascular endothelial growth factor (VEGF) injections on intraocular pressure have not been fully characterized, and the development of sustained ocular hypertension could adversely affect patients who are at risk of glaucomatous optic neuropathy. As expected, volume-driven, acute ocular hypertension immediately follows intravitreal injection, but this pressure elevation is generally transient and well tolerated. Several medications have been investigated to limit acute ocular hypertension following anti-VEGF therapy, but the benefits of pretreatment are not conclusive. Chronic, sustained ocular hypertension, distinct from the short-term acute ocular hypertension after each injection, has also been associated with repeated intravitreal anti-VEGF injections. Risk factors for chronic ocular hypertension include the total number of injections, a greater frequency of injection, and preexisting glaucoma. Proposed mechanisms for chronic ocular hypertension include microparticle obstruction, toxic or inflammatory effects on trabecular meshwork, as well as alterations in outflow facility by anti-VEGF agents. Although limiting anti-VEGF therapy could minimize the risk of both acute and chronic ocular hypertension, foregoing anti-VEGF therapy risks progression of various macular diseases with resulting permanent central vision loss. While definitive evidence of damage to the retinal nerve fiber layer is lacking, patients receiving repeated injections should be monitored for ocular hypertension and patients in whom sustained ocular hypertension subsequently developed should be periodically monitored for glaucomatous changes with optic nerve optical coherence tomography and static visual fields.
Collapse
Affiliation(s)
- Peter Bracha
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA.
| | - Nicholas A Moore
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Thomas A Ciulla
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA; Retina Service, Midwest Eye Institute, Indianapolis, Indiana, USA
| | - Darrell WuDunn
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Louis B Cantor
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA
| |
Collapse
|
22
|
Reina-Torres E, Wen JC, Liu KC, Li G, Sherwood JM, Chang JYH, Challa P, Flügel-Koch CM, Stamer WD, Allingham RR, Overby DR. VEGF as a Paracrine Regulator of Conventional Outflow Facility. Invest Ophthalmol Vis Sci 2017; 58:1899-1908. [PMID: 28358962 PMCID: PMC5374885 DOI: 10.1167/iovs.16-20779] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Purpose Vascular endothelial growth factor (VEGF) regulates microvascular endothelial permeability, and the permeability of Schlemm's canal (SC) endothelium influences conventional aqueous humor outflow. We hypothesize that VEGF signaling regulates outflow facility. Methods We measured outflow facility (C) in enucleated mouse eyes perfused with VEGF-A164a, VEGF-A165b, VEGF-D, or inhibitors to VEGF receptor 2 (VEGFR-2). We monitored VEGF-A secretion from human trabecular meshwork (TM) cells by ELISA after 24 hours of static culture or cyclic stretch. We used immunofluorescence microscopy to localize VEGF-A protein within the TM of mice. Results VEGF-A164a increased C in enucleated mouse eyes. Cyclic stretch increased VEGF-A secretion by human TM cells, which corresponded to VEGF-A localization in the TM of mice. Blockade of VEGFR-2 decreased C, using either of the inhibitors SU5416 or Ki8751 or the inactive splice variant VEGF-A165b. VEGF-D increased C, which could be blocked by Ki8751. Conclusions VEGF is a paracrine regulator of conventional outflow facility that is secreted by TM cells in response to mechanical stress. VEGF affects facility via VEGFR-2 likely at the level of SC endothelium. Disruption of VEGF signaling in the TM may explain why anti-VEGF therapy is associated with decreased outflow facility and sustained ocular hypertension.
Collapse
Affiliation(s)
- Ester Reina-Torres
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Joanne C Wen
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Katy C Liu
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Guorong Li
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Joseph M Sherwood
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Jason Y H Chang
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Pratap Challa
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Cassandra M Flügel-Koch
- Department of Anatomy II, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen, Germany
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - R Rand Allingham
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, United Kingdom
| |
Collapse
|
23
|
O'Callaghan J, Crosbie DE, Cassidy PS, Sherwood JM, Flügel-Koch C, Lütjen-Drecoll E, Humphries MM, Reina-Torres E, Wallace D, Kiang AS, Campbell M, Stamer WD, Overby DR, O'Brien C, Tam LCS, Humphries P. Therapeutic potential of AAV-mediated MMP-3 secretion from corneal endothelium in treating glaucoma. Hum Mol Genet 2017; 26:1230-1246. [PMID: 28158775 PMCID: PMC5390678 DOI: 10.1093/hmg/ddx028] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 01/18/2017] [Indexed: 11/13/2022] Open
Abstract
Intraocular pressure (IOP) is maintained as a result of the balance between production of aqueous humour (AH) by the ciliary processes and hydrodynamic resistance to its outflow through the conventional outflow pathway comprising the trabecular meshwork (TM) and Schlemm's canal (SC). Elevated IOP, which can be caused by increased resistance to AH outflow, is a major risk factor for open-angle glaucoma. Matrix metalloproteinases (MMPs) contribute to conventional aqueous outflow homeostasis in their capacity to remodel extracellular matrices, which has a direct impact on aqueous outflow resistance and IOP. We observed decreased MMP-3 activity in human glaucomatous AH compared to age-matched normotensive control AH. Treatment with glaucomatous AH resulted in significantly increased transendothelial resistance of SC endothelial and TM cell monolayers and reduced monolayer permeability when compared to control AH, or supplemented treatment with exogenous MMP-3.Intracameral inoculation of AAV-2/9 containing a CMV-driven MMP-3 gene (AAV-MMP-3) into wild type mice resulted in efficient transduction of corneal endothelium and an increase in aqueous concentration and activity of MMP-3. Most importantly, AAV-mediated expression of MMP-3 increased outflow facility and decreased IOP, and controlled expression using an inducible promoter activated by topical administration of doxycycline achieved the same effect. Ultrastructural analysis of MMP-3 treated matrices by transmission electron microscopy revealed remodelling and degradation of core extracellular matrix components. These results indicate that periodic induction, via use of an eye drop, of AAV-mediated secretion of MMP-3 into AH could have therapeutic potential for those cases of glaucoma that are sub-optimally responsive to conventional pressure-reducing medications.
Collapse
Affiliation(s)
- Jeffrey O'Callaghan
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| | - Darragh E Crosbie
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| | - Paul S Cassidy
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| | - Joseph M Sherwood
- Department of Bioengineering, Imperial College London, London, SW7 2BX, UK
| | - Cassandra Flügel-Koch
- Department of Anatomy II, University of Erlangen-Nürnberg, D-91054 Erlangen, Germany
| | - Elke Lütjen-Drecoll
- Department of Anatomy II, University of Erlangen-Nürnberg, D-91054 Erlangen, Germany
| | - Marian M Humphries
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| | - Ester Reina-Torres
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| | - Deborah Wallace
- Clinical Research Centre, UCD School of Medicine and Medical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Anna-Sophia Kiang
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| | - Matthew Campbell
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| | - W Daniel Stamer
- Departments of Ophthalmology and Biomedical Engineering, Duke University, Durham, NC, USA
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, SW7 2BX, UK
| | - Colm O'Brien
- Department of Ophthalmology, Mater Misericordiae University Hospital, Dublin, D7, Ireland
| | - Lawrence C S Tam
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| | - Peter Humphries
- Ocular Genetics Unit, Smurfit Institute of Genetics, University of Dublin, Trinity College, Dublin, D2, Ireland
| |
Collapse
|
24
|
Tam LCS, Reina-Torres E, Sherwood JM, Cassidy PS, Crosbie DE, Lütjen-Drecoll E, Flügel-Koch C, Perkumas K, Humphries MM, Kiang AS, O'Callaghan J, Callanan JJ, Read AT, Ethier CR, O'Brien C, Lawrence M, Campbell M, Stamer WD, Overby DR, Humphries P. Enhancement of Outflow Facility in the Murine Eye by Targeting Selected Tight-Junctions of Schlemm's Canal Endothelia. Sci Rep 2017; 7:40717. [PMID: 28091584 PMCID: PMC5238500 DOI: 10.1038/srep40717] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 12/09/2016] [Indexed: 11/12/2022] Open
Abstract
The juxtacanalicular connective tissue of the trabecular meshwork together with inner wall endothelium of Schlemm’s canal (SC) provide the bulk of resistance to aqueous outflow from the anterior chamber. Endothelial cells lining SC elaborate tight junctions (TJs), down-regulation of which may widen paracellular spaces between cells, allowing greater fluid outflow. We observed significant increase in paracellular permeability following siRNA-mediated suppression of TJ transcripts, claudin-11, zonula-occludens-1 (ZO-1) and tricellulin in human SC endothelial monolayers. In mice claudin-11 was not detected, but intracameral injection of siRNAs targeting ZO-1 and tricellulin increased outflow facility significantly. Structural qualitative and quantitative analysis of SC inner wall by transmission electron microscopy revealed significantly more open clefts between endothelial cells treated with targeting, as opposed to non-targeting siRNA. These data substantiate the concept that the continuity of SC endothelium is an important determinant of outflow resistance, and suggest that SC endothelial TJs represent a specific target for enhancement of aqueous movement through the conventional outflow system.
Collapse
Affiliation(s)
- Lawrence C S Tam
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland
| | - Ester Reina-Torres
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland.,Department of Bioengineering, Imperial College London, London, UK
| | | | - Paul S Cassidy
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland
| | - Darragh E Crosbie
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland
| | | | | | | | - Marian M Humphries
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland
| | - Anna-Sophia Kiang
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland
| | - Jeffrey O'Callaghan
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland
| | - John J Callanan
- Ross University School of Veterinary Medicine, P. O. Box 334, Basseterre, St. Kitts, West Indies
| | - A Thomas Read
- Department of Ophthalmology and Vision Sciences, University of Toronto, Canada
| | - C Ross Ethier
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, USA
| | - Colm O'Brien
- Ophthalmology, Mater Hospital, UCD School of Medicine, Dublin, Ireland
| | | | - Matthew Campbell
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC, USA
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, UK
| | - Pete Humphries
- Neurovascular Genetics, Smurfit Institute of Genetics, Trinity College, University of Dublin, Dublin 2, Ireland
| |
Collapse
|
25
|
Paula JS, O'Brien C, Stamer WD. Life under pressure: The role of ocular cribriform cells in preventing glaucoma. Exp Eye Res 2016; 151:150-9. [PMID: 27567558 DOI: 10.1016/j.exer.2016.08.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Revised: 08/22/2016] [Accepted: 08/23/2016] [Indexed: 02/08/2023]
Abstract
Primary open-angle glaucoma is a multifactorial blinding disease often impacting the two pressure-sensitive regions of the eye: the conventional outflow pathway and the optic nerve head (ONH). The connective tissues that span these two openings in the globe are the trabecular meshwork of the conventional outflow pathway and the lamina cribrosa of the ONH. Resident cribiform cells of these two regions are responsible for actively remodeling and maintaining their connective tissues. In glaucoma, aberrant maintenance of the juxtacanalicular tissues (JCT) of the conventional outflow pathway results in ocular hypertension and pathological remodeling of the lamina cribrosa results in ONH cupping, damaging retinal ganglion cell axons. Interestingly, cells cultured from the lamina cribrosa and the JCT of the trabecular meshwork have similarities regarding gene expression, protein production, plus cellular responses to growth factors and mechanical stimuli. This review compares and contrasts the current knowledge of these two cell types, whose health is critical for protecting the eye from glaucomatous changes. In response to pressure gradients across their respective cribiform tissues, the goal is to better understand and differentiate healthy from pathological behavior of these two cell types.
Collapse
Affiliation(s)
- Jayter S Paula
- Department of Ophthalmology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil; Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA
| | - Colm O'Brien
- Ophthalmology, UCD School of Medicine, Mater Hospital, Dublin, Ireland
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA.
| |
Collapse
|
26
|
Rybkin I, Gerometta R, Fridman G, Candia O, Danias J. Model systems for the study of steroid-induced IOP elevation. Exp Eye Res 2016; 158:51-58. [PMID: 27450911 DOI: 10.1016/j.exer.2016.07.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Revised: 06/24/2016] [Accepted: 07/19/2016] [Indexed: 12/16/2022]
Abstract
Steroid-induced IOP elevation affects a significant number of patients. It results from a decrease in outflow facility of the aqueous humor. To understand the pathophysiology of this condition a number of model systems have been created. These include ex-vivo cell and organ cultures as well as in-vivo animal models in organisms ranging from rodents to primates. These model systems can be used to investigate specific aspects of steroid-induced IOP elevation. This brief review summarizes the strengths and limitations of the various model systems and provides examples of where these systems have been successfully used to advance our understanding of steroid-induced IOP elevation.
Collapse
Affiliation(s)
- Ilya Rybkin
- Department of Cell Biology, SUNY Downstate, NY, USA
| | - Rosana Gerometta
- Departamento de Oftalmologia, Facultad de Medicina, Universidad Nacional del Nordeste, Corrientes, Argentina; Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | | | - Oscar Candia
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - John Danias
- Department of Cell Biology, SUNY Downstate, NY, USA; Department of Ophthalmology, SUNY Downstate, NY, USA.
| |
Collapse
|
27
|
Stamer WD, Clark AF. The many faces of the trabecular meshwork cell. Exp Eye Res 2016; 158:112-123. [PMID: 27443500 DOI: 10.1016/j.exer.2016.07.009] [Citation(s) in RCA: 169] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 06/19/2016] [Accepted: 07/16/2016] [Indexed: 12/26/2022]
Abstract
With the combined purpose of facilitating useful vision over a lifetime, a number of ocular cells have evolved specialized features not found elsewhere in the body. The trabecular meshwork (TM) cell at the irido-corneal angle, which is a key regulator of intraocular pressure, is no exception. Examination of cells in culture isolated from the human TM has shown that they are unique in many ways, displaying characteristic features of several different cell types. Thus, these neural crest derived cells display expression patterns and behaviors typical of endothelia, fibroblasts, smooth muscle and macrophages, owing to the multiple roles and two distinct environments where they operate to maintain intraocular pressure homeostasis. In most individuals, TM cells function normally over a lifetime in the face of persistent stressors, including phagocytic, oxidative, mechanical and metabolic stress. Study of TM cells isolated from ocular hypertensive eyes has shown a compromised ability to perform their daily duties. This review highlights the many responsibilities of the TM cell and its challenges, progress in our understanding of TM biology over the past 30 years, as well as discusses unanswered questions about TM dysfunction that results in IOP dysregulation and glaucoma.
Collapse
Affiliation(s)
- W Daniel Stamer
- Departments of Ophthalmology and Biomedical Engineering, Duke University, Durham, NC, United States
| | - Abbot F Clark
- North Texas Eye Research Institute, University of North Texas Health Science Center, Ft. Worth, TX, United States.
| |
Collapse
|
28
|
The role of integrins in glaucoma. Exp Eye Res 2016; 158:124-136. [PMID: 27185161 DOI: 10.1016/j.exer.2016.05.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 05/06/2016] [Accepted: 05/10/2016] [Indexed: 01/04/2023]
Abstract
Integrins are a family of heterodimeric transmembrane receptors that mediate adhesion to the extracellular matrix (ECM). In addition to their role as adhesion receptors, integrins can act as ''bidirectional signal transducers'' that coordinate a large number of cellular activities in response to the extracellular environment and intracellular signaling events. This bidirectional signaling helps maintain tissue homeostasis. Dysregulated bidirectional signaling, however, could trigger the propagation of feedback loops that can lead to the establishment of a disease state such as glaucoma. Here we discuss the role of integrins and bidirectional signaling as they relate to the glaucomatous phenotype with special emphasis on the αvβ3 integrin. We present evidence that this particular integrin may have a significant impact on the pathogenesis of glaucoma.
Collapse
|
29
|
Gal-Or O, Dotan A, Dachbash M, Tal K, Nisgav Y, Weinberger D, Ehrlich R, Livnat T. Bevacizumab clearance through the iridocorneal angle following intravitreal injection in a rat model. Exp Eye Res 2016; 145:412-416. [PMID: 26923799 DOI: 10.1016/j.exer.2016.02.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 12/29/2015] [Accepted: 02/23/2016] [Indexed: 11/17/2022]
Abstract
Antivascular endothelial growth factor (Anti-VEGF) agents have been widely used for a variety of ocular disorders. The etiology of sustained ocular hypertension following intravitreal administration of anti-VEGF agents is yet to be unraveled. Our study investigates and characterizes the presence of intravitreally injected bevacizumab in the aqueous outflow channels of a rat model. Choroidal neovascularization (CNV) was induced by diode laser photocoagulation to the right eye of twelve Brown Norway rats. Bevacizumab (25 mg/ml) was injected intravitreally after 3 days. Immediately after bevacizumab injection, and 3, 6, 24 and 48 h later, animals were euthanized for immunofluorescence staining. Donkey anti-human IgG labeled with Alexa Fluor(®) 488 was used for bevacizumab immunoreactivity detection. Anti-CD31 antibody was used as a marker for Schlemm's canal endothelial cells. Untreated eyes were used as negative controls. The intensity of the immunostaining was analyzed qualitatively. Bevacizumab immunoreactivity was found in the aqueous outflow channels including the trabecular meshwork and Schlemm's canal immediately after injection, and declined incrementally within the following hours. Forty-eight hours after the injection, no bevacizumab staining was detected in the aqueous outflow channel structures. Our manuscript demonstrates the presence of bevacizumab in the trabecular meshwork and Schlemm's canal structures after intravitreal injection in a CNV induced rat model. Bevacizumab molecules passed through the aqueous outflow channels within 48 h after intravitreal bevacizumab injection.
Collapse
Affiliation(s)
- Orly Gal-Or
- Department of Ophthalmology, Rabin Medical Center, Petach Tikva, Israel.
| | - Assaf Dotan
- Department of Ophthalmology, Rabin Medical Center, Petach Tikva, Israel.
| | - Mor Dachbash
- Eye Research Laboratory, Felsenstein Medical Research Center, Rabin Medical Center, Petach Tikva, Israel.
| | - Kfir Tal
- Department of Ophthalmology, Rabin Medical Center, Petach Tikva, Israel.
| | - Yael Nisgav
- Eye Research Laboratory, Felsenstein Medical Research Center, Rabin Medical Center, Petach Tikva, Israel.
| | - Dov Weinberger
- Department of Ophthalmology, Rabin Medical Center, Petach Tikva, Israel; Eye Research Laboratory, Felsenstein Medical Research Center, Rabin Medical Center, Petach Tikva, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
| | - Rita Ehrlich
- Department of Ophthalmology, Rabin Medical Center, Petach Tikva, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
| | - Tami Livnat
- Department of Ophthalmology, Rabin Medical Center, Petach Tikva, Israel; Eye Research Laboratory, Felsenstein Medical Research Center, Rabin Medical Center, Petach Tikva, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
| |
Collapse
|
30
|
Cai J, Perkumas KM, Qin X, Hauser MA, Stamer WD, Liu Y. Expression Profiling of Human Schlemm's Canal Endothelial Cells From Eyes With and Without Glaucoma. Invest Ophthalmol Vis Sci 2015; 56:6747-53. [PMID: 26567786 PMCID: PMC4614909 DOI: 10.1167/iovs.15-17720] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 09/12/2015] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Ocular hypertension is a major risk factor for glaucoma and the inner wall of Schlemm's canal (SC) endothelia participates in the regulation of aqueous humor outflow resistance. This study aimed to identify differentially expressed genes in primary cultures of SC cells from glaucoma patients. METHODS This study examined SC samples from three glaucoma cases and four controls. Schlemm's canal cells were isolated from eight different postmortem human eyes. Total RNA was extracted, labeled, and hybridized to Illumina HumanWG-6 BeadChips containing probes for approximately 47,000 human transcripts. After extracting the data using Illumina GenomeStudio software, the data were normalized and analyzed using the R package limma in Bioconductor. Using Protein ANalysis THrough Evolutionary Relationships (PANTHER) software, gene ontology analysis of highly expressed genes was executed in controls and glaucoma groups separately. Pathway analysis was performed with differentially expressed genes using WebGestalt (WEB-based GEne SeT AnaLysis Toolkit). Selected genes were validated using droplet digital PCR (ddPCR). RESULTS Gene ontology analysis indicated similar functional categories in cases and controls. Differential analysis identified a total of 113 genes with at least 2-fold expression changes in cases. Pathway analysis indicated significant enrichment of genes in cell adhesion, heparin binding, glycosaminoglycan binding, filopodium, and extracellular matrix remodeling. Eighteen selected genes with differential expression were successfully validated using ddPCR. CONCLUSIONS This study represents the first genome-wide expression study of human primary SC cells from glaucoma patients and provides a potential list of targets regulating SC cell stiffness and pore formation, eventually the outflow resistance in glaucoma individuals.
Collapse
Affiliation(s)
- Jingwen Cai
- Department of Cellular Biology and Anatomy, Georgia Regents University, Augusta, Georgia, United States
| | - Kristin M. Perkumas
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Xuejun Qin
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina, United States
- Department of Medicine, Duke University, Durham, North Carolina, United States
| | - Michael A. Hauser
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina, United States
- Department of Medicine, Duke University, Durham, North Carolina, United States
| | - W. Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
| | - Yutao Liu
- Department of Cellular Biology and Anatomy, Georgia Regents University, Augusta, Georgia, United States
- James & Jean Culver Vision Discovery Institute, Georgia Regents University, Augusta, Georgia, United States
- Center for Biotechnology and Genomic Medicine, Georgia Regents University, Augusta, Georgia, United States
| |
Collapse
|
31
|
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.
Collapse
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.
| |
Collapse
|
32
|
Wiggs JL. Glaucoma Genes and Mechanisms. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 134:315-42. [PMID: 26310163 DOI: 10.1016/bs.pmbts.2015.04.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Genetic studies have yielded important genes contributing to both early-onset and adult-onset forms of glaucoma. The proteins encoded by the current collection of glaucoma genes participate in a broad range of cellular processes and biological systems. Approximately half the glaucoma-related genes function in the extracellular matrix, however proteins involved in cytokine signaling, lipid metabolism, membrane biology, regulation of cell division, autophagy, and ocular development also contribute to the disease pathogenesis. While the function of these proteins in health and disease are not completely understood, recent studies are providing insight into underlying disease mechanisms, a critical step toward the development of gene-based therapies. In this review, genes known to cause early-onset glaucoma or contribute to adult-onset glaucoma are organized according to the cell processes or biological systems that are impacted by the function of the disease-related protein product.
Collapse
Affiliation(s)
- Janey L Wiggs
- Harvard Medical School, and Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA.
| |
Collapse
|
33
|
A biomimetic Schlemm's canal inner wall: A model to study outflow physiology, glaucoma pathology and high-throughput drug screening. Biomaterials 2015; 65:86-92. [PMID: 26142779 DOI: 10.1016/j.biomaterials.2015.06.034] [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] [Received: 03/15/2015] [Revised: 06/11/2015] [Accepted: 06/18/2015] [Indexed: 11/22/2022]
Abstract
Glaucoma is a disease that damages the optic nerve, frequently leading to blindness. Elevated intraocular pressure (IOP) is the only modifiable risk factor for glaucoma, which is expected to affect 80 million people by 2020, causing bilateral blindness in over 10 million individuals. Because pathological changes to Schlemm's canal (SC) may account for significant resistance to outflow, there is considerable interest in characterizing and evaluating the Schlemm's canal as a target for glaucoma therapeutics. In conventional, two-dimensional culture, human Schlemm's canal (HSC) cells lose spatial, mechanical and biochemical cues, resulting in altered gene expression and cell signaling than observed in vivo, compromising the clinical relevance of data obtained from such systems. Here, we report, for the first time, that 3D culture of HSC cells on microfabricated scaffolds with defined physical and biochemical cues, rescued expression of key HSC markers, VE-cadherin and PECAM1, and mediated pore formation, crucial for the Schlemm's canal regulation of IOP. We demonstrated that following treatment with the glaucopathogenic agent, TGF-β2, HSC cells undergo an endothelial-mesenchymal transition, which together with the increase in extracellular matrix (ECM) proteins might account for the decrease in outflow facility observed in patients with high TGF-β2 levels in their aqueous humor. We also demonstrated that unlike 2D cultures, 3D cultures of HSC cells are amenable to gene transfer. Thus, our data imply that 3D culture of HSC cells may be used as a platform to advance our understanding of HSC physiology and pathology and as a model for high-throughput drug and gene screening.
Collapse
|
34
|
Vranka JA, Kelley MJ, Acott TS, Keller KE. Extracellular matrix in the trabecular meshwork: intraocular pressure regulation and dysregulation in glaucoma. Exp Eye Res 2015; 133:112-25. [PMID: 25819459 DOI: 10.1016/j.exer.2014.07.014] [Citation(s) in RCA: 251] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 07/14/2014] [Accepted: 07/16/2014] [Indexed: 12/30/2022]
Abstract
The trabecular meshwork (TM) is located in the anterior segment of the eye and is responsible for regulating the outflow of aqueous humor. Increased resistance to aqueous outflow causes intraocular pressure to increase, which is the primary risk factor for glaucoma. TM cells reside on a series of fenestrated beams and sheets through which the aqueous humor flows to exit the anterior chamber via Schlemm's canal. The outer trabecular cells are phagocytic and are thought to function as a pre-filter. However, most of the outflow resistance is thought to be from the extracellular matrix (ECM) of the juxtacanalicular region, the deepest portion of the TM, and from the inner wall basement membrane of Schlemm's canal. It is becoming increasingly evident that the extracellular milieu is important in maintaining the integrity of the TM. In glaucoma, not only have ultrastructural changes been observed in the ECM of the TM, and a significant number of mutations in ECM genes been noted, but the stiffness of glaucomatous TM appears to be greater than that of normal tissue. Additionally, TGFβ2 has been found to be elevated in the aqueous humor of glaucoma patients and is assumed to be involved in ECM changes deep with the juxtacanalicular region of the TM. This review summarizes the current literature on trabecular ECM as well as the development and function of the TM. Animal models and organ culture models targeting specific ECM molecules to investigate the mechanisms of glaucoma are described. Finally, the growing number of mutations that have been identified in ECM genes and genes that modulate ECM in humans with glaucoma are documented.
Collapse
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.
| |
Collapse
|
35
|
Vranka JA, Bradley JM, Yang YF, Keller KE, Acott TS. Mapping molecular differences and extracellular matrix gene expression in segmental outflow pathways of the human ocular trabecular meshwork. PLoS One 2015; 10:e0122483. [PMID: 25826404 PMCID: PMC4380331 DOI: 10.1371/journal.pone.0122483] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 02/22/2015] [Indexed: 01/09/2023] Open
Abstract
Elevated intraocular pressure (IOP) is the primary risk factor for glaucoma, and lowering IOP remains the only effective treatment for glaucoma. The trabecular meshwork (TM) in the anterior chamber of the eye regulates IOP by generating resistance to aqueous humor outflow. Aqueous humor outflow is segmental, but molecular differences between high and low outflow regions of the TM are poorly understood. In this study, flow regions of the TM were characterized using fluorescent tracers and PCR arrays. Anterior segments from human donor eyes were perfused at physiological pressure in an ex vivo organ culture system. Fluorescently-labeled microspheres of various sizes were perfused into anterior segments to label flow regions. Actively perfused microspheres were segmentally distributed, whereas microspheres soaked passively into anterior segments uniformly labeled the TM and surrounding tissues with no apparent segmentation. Cell-tracker quantum dots (20 nm) were localized to the outer uveal and corneoscleral TM, whereas larger, modified microspheres (200 nm) localized throughout the TM layers and Schlemm’s canal. Distribution of fluorescent tracers demonstrated a variable labeling pattern on both a macro- and micro-scale. Quantitative PCR arrays allowed identification of a variety of extracellular matrix genes differentially expressed in high and low flow regions of the TM. Several collagen genes (COL16A1, COL4A2, COL6A1 and 2) and MMPs (1, 2, 3) were enriched in high, whereas COL15A1, and MMP16 were enriched in low flow regions. Matrix metalloproteinase activity was similar in high and low regions using a quantitative FRET peptide assay, whereas protein levels in tissues showed modest regional differences. These gene and protein differences across regions of the TM provide further evidence for a molecular basis of segmental flow routes within the aqueous outflow pathway. New insight into the molecular mechanisms of segmental aqueous outflow may aid in the design and delivery of improved treatments for glaucoma patients.
Collapse
Affiliation(s)
- Janice A. Vranka
- Casey Eye Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, Oregon, United States of America
- * E-mail:
| | - John M. Bradley
- Casey Eye Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, Oregon, United States of America
| | - Yong-Feng Yang
- Casey Eye Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, Oregon, United States of America
| | - Kate E. Keller
- Casey Eye Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, Oregon, United States of America
| | - Ted S. Acott
- Casey Eye Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, Oregon, United States of America
| |
Collapse
|
36
|
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.
Collapse
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
| |
Collapse
|
37
|
Lei Y, Stamer WD, Wu J, Sun X. Endothelial nitric oxide synthase-related mechanotransduction changes in aged porcine angular aqueous plexus cells. Invest Ophthalmol Vis Sci 2014; 55:8402-8. [PMID: 25377220 DOI: 10.1167/iovs.14-14992] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
PURPOSE To investigate effects of aging on endothelial nitric oxide synthase (eNOS) expression and signaling in angular aqueous plexus (AAP) (functional equivalent to human Schlemm's canal) cells subjected to shear stress. METHODS The AAP cells were isolated differentially from porcine outflow tissues using puromycin selection. Cell aging was induced by culturing cells in hyperoxia condition (40% oxygen and 5% carbon dioxide) for 14 days. The AAP cells grown in chamber slides were exposed to a shear stress of 8 dynes/cm(2) for 24 hours. Expression of eNOS, eNOS-phospho Thr495, eNOS-phospho Ser1177, and Akt-phospho was tested by Western blot analysis and immunofluorescence staining. Nitric oxide (NO) levels were measured using the Griess assay. RESULTS Compared with control, eNOS levels in aged cells were significantly reduced by 60% (P < 0.05; n = 6). Phosphorylation of eNOS at Ser1177 and Akt at Ser473 was 63% and 80% lower in aged cells, respectively, whereas phosphorylation of the eNOS inhibition site (Thr495) increased by 6.1-fold (P < 0.05; n = 6). Shear stress (8 dynes/cm(2) for 24 hours) increased eNOS abundance (total protein and at cell borders) and phosphorylation at Ser1177 by 1.7-fold and 1.8-fold, respectively (P < 0.05; n = 6), whereas aged cells were unresponsive. In control cells exposed to shear stress, the NO concentration was 1.8-fold higher than in the static group (P < 0.05; n = 4); however, aged cells were unresponsive to shear stress (mean ± SD, 4.3 ± 1.3 vs. 4.1 ± 1.4 μM). CONCLUSIONS Aged AAP cells appear compromised in their mechanotransduction machinery involving eNOS, the protein product of the gene, NOS3, polymorphisms of which impart a risk for the development of glaucoma.
Collapse
Affiliation(s)
- Yuan Lei
- Research Centre, Eye and ENT Hospital, Shanghai Medical College, Fudan University
| | | | - Jihong Wu
- Research Centre, Eye and ENT Hospital, Shanghai Medical College, Fudan University Shanghai Key Laboratory of Visual Impairment and Restoration, Eye and ENT Hospital, Shanghai Medical College, Fudan University
| | - Xinghuai Sun
- Key Laboratory of Myopia, Ministry of Health (Fudan University) Shanghai Key Laboratory of Visual Impairment and Restoration, Eye and ENT Hospital, Shanghai Medical College, Fudan University Department of Ophthalmology and Vision Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Fudan University
| |
Collapse
|
38
|
Ding QJ, Zhu W, Cook AC, Anfinson KR, Tucker BA, Kuehn MH. Induction of trabecular meshwork cells from induced pluripotent stem cells. Invest Ophthalmol Vis Sci 2014; 55:7065-72. [PMID: 25298418 DOI: 10.1167/iovs.14-14800] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Loss or dysfunction of trabecular meshwork (TM) cells has been associated with the development of pathologically elevated IOP, and it is conceivable that replacement of damaged TM cells could restore function to the TM. We propose that the use of TM-like cells derived from induced pluripotent stem cells (iPSCs) created from a patient's own dermal fibroblasts offers the best solution to this challenge. Here we demonstrate that mouse iPSCs can be induced to differentiate into TM-like cells suitable for autologous transplantation. METHODS Directed induction of stem cell differentiation was achieved through coculture of mouse iPSCs with human TM cells for up to 21 days. The resultant TM-like cells (iPSC-TM) were characterized morphologically, immunohistochemically, and functionally. RESULTS The iPSC-TM cells closely resembled cultured human TM cells morphologically and began to express many markers of TM cells while ceasing to express pluripotency markers such as Nanog, Oct4, and Sox2. Functionally, these cells developed the ability to phagocytose particles. Finally, exposure to dexamethasone or phorbol 12-myristate acetate caused a distinct increase in the production and secretion of myocilin and matrix metalloproteinase-3, respectively, behavior characteristic of TM cells. CONCLUSIONS Our data demonstrate that iPSCs can be induced to assume a phenotype that resembles native TM cells in many important aspects. Not only do these cells represent a valuable research tool, but transplantation into glaucomatous eyes with elevated IOP may also restore function to the TM, resulting in re-establishment of IOP.
Collapse
Affiliation(s)
- Qiong J Ding
- The Stephen A. Wynn Institute for Vision Research, Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
| | - Wei Zhu
- The Stephen A. Wynn Institute for Vision Research, Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
| | - Amy C Cook
- The Stephen A. Wynn Institute for Vision Research, Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
| | - Kristin R Anfinson
- The Stephen A. Wynn Institute for Vision Research, Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
| | - Budd A Tucker
- The Stephen A. Wynn Institute for Vision Research, Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
| | - Markus H Kuehn
- The Stephen A. Wynn Institute for Vision Research, Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
| |
Collapse
|
39
|
Braakman ST, Pedrigi RM, Read AT, Smith JAE, Stamer WD, Ethier CR, Overby DR. Biomechanical strain as a trigger for pore formation in Schlemm's canal endothelial cells. Exp Eye Res 2014; 127:224-35. [PMID: 25128579 PMCID: PMC4175173 DOI: 10.1016/j.exer.2014.08.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 08/01/2014] [Accepted: 08/05/2014] [Indexed: 02/08/2023]
Abstract
The bulk of aqueous humor passing through the conventional outflow pathway must cross the inner wall endothelium of Schlemm's canal (SC), likely through micron-sized transendothelial pores. SC pore density is reduced in glaucoma, possibly contributing to obstructed aqueous humor outflow and elevated intraocular pressure (IOP). Little is known about the mechanisms of pore formation; however, pores are often observed near dome-like cellular outpouchings known as giant vacuoles (GVs) where significant biomechanical strain acts on SC cells. We hypothesize that biomechanical strain triggers pore formation in SC cells. To test this hypothesis, primary human SC cells were isolated from three non-glaucomatous donors (aged 34, 44 and 68), and seeded on collagen-coated elastic membranes held within a membrane stretching device. Membranes were then exposed to 0%, 10% or 20% equibiaxial strain, and the cells were aldehyde-fixed 5 min after the onset of strain. Each membrane contained 3-4 separate monolayers of SC cells as replicates (N = 34 total monolayers), and pores were assessed by scanning electron microscopy in 12 randomly selected regions (∼65,000 μm(2) per monolayer). Pores were identified and counted by four independent masked observers. Pore density increased with strain in all three cell lines (p < 0.010), increasing from 87 ± 36 pores/mm(2) at 0% strain to 342 ± 71 at 10% strain; two of the three cell lines showed no additional increase in pore density beyond 10% strain. Transcellular "I-pores" and paracellular "B-pores" both increased with strain (p < 0.038), however B-pores represented the majority (76%) of pores. Pore diameter, in contrast, appeared unaffected by strain (p = 0.25), having a mean diameter of 0.40 μm for I-pores (N = 79 pores) and 0.67 μm for B-pores (N = 350 pores). Pore formation appears to be a mechanosensitive process that is triggered by biomechanical strain, suggesting that SC cells have the ability to modulate local pore density and filtration characteristics of the inner wall endothelium based on local biomechanical cues. The molecular mechanisms of pore formation and how they become altered in glaucoma may be studied in vitro using stretched SC cells.
Collapse
Affiliation(s)
- Sietse T Braakman
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Ryan M Pedrigi
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - A Thomas Read
- Department of Ophthalmology and Vision Sciences, University of Toronto, Canada
| | - James A E Smith
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University Medical School, USA
| | - C Ross Ethier
- Department of Bioengineering, Imperial College London, London, United Kingdom; Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, USA
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, United Kingdom.
| |
Collapse
|
40
|
Abstract
Increased flow resistance is responsible for the elevated intraocular pressure characteristic of glaucoma, but the cause of this resistance increase is not known. We tested the hypothesis that altered biomechanical behavior of Schlemm's canal (SC) cells contributes to this dysfunction. We used atomic force microscopy, optical magnetic twisting cytometry, and a unique cell perfusion apparatus to examine cultured endothelial cells isolated from the inner wall of SC of healthy and glaucomatous human eyes. Here we establish the existence of a reduced tendency for pore formation in the glaucomatous SC cell--likely accounting for increased outflow resistance--that positively correlates with elevated subcortical cell stiffness, along with an enhanced sensitivity to the mechanical microenvironment including altered expression of several key genes, particularly connective tissue growth factor. Rather than being seen as a simple mechanical barrier to filtration, the endothelium of SC is seen instead as a dynamic material whose response to mechanical strain leads to pore formation and thereby modulates the resistance to aqueous humor outflow. In the glaucomatous eye, this process becomes impaired. Together, these observations support the idea of SC cell stiffness--and its biomechanical effects on pore formation--as a therapeutic target in glaucoma.
Collapse
|
41
|
Truong TN, Li H, Hong YK, Chen L. Novel characterization and live imaging of Schlemm's canal expressing Prox-1. PLoS One 2014; 9:e98245. [PMID: 24827370 PMCID: PMC4020937 DOI: 10.1371/journal.pone.0098245] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 04/29/2014] [Indexed: 11/18/2022] Open
Abstract
Schlemm's canal is an important structure of the conventional aqueous humor outflow pathway and is critically involved in regulating the intraocular pressure. In this study, we report a novel finding that prospero homeobox protein 1 (Prox-1), the master control gene for lymphatic development, is expressed in Schlemm's canal. Moreover, we provide a novel in vivo method of visualizing Schlemm's canal using a transgenic mouse model of Prox-1-green fluorescent protein (GFP). The anatomical location of Prox-1+ Schlemm's canal was further confirmed by in vivo gonioscopic examination and ex vivo immunohistochemical analysis. Additionally, we show that the Schlemm's canal is distinguishable from typical lymphatic vessels by lack of lymphatic vessel endothelial hyaluronan receptor (LYVE-1) expression and absence of apparent sprouting reaction when inflammatory lymphangiogenesis occurred in the cornea. Taken together, our findings offer new insights into Schlemm's canal and provide a new experimental model for live imaging of this critical structure to help further our understanding of the aqueous humor outflow. This may lead to new avenues toward the development of novel therapeutic intervention for relevant diseases, most notably glaucoma.
Collapse
Affiliation(s)
- Tan N. Truong
- Graduate Group in Vision Science, University of California, Berkeley, California, United States of America
- Center for Eye Disease and Development, Program in Vision Science and School of Optometry, University of California, Berkeley, California, United States of America
| | - Hannah Li
- Center for Eye Disease and Development, Program in Vision Science and School of Optometry, University of California, Berkeley, California, United States of America
| | - Young-Kwon Hong
- Department of Surgery and Department of Biochemistry and Molecular Biology, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Lu Chen
- Graduate Group in Vision Science, University of California, Berkeley, California, United States of America
- Center for Eye Disease and Development, Program in Vision Science and School of Optometry, University of California, Berkeley, California, United States of America
- The Francis I. Proctor Foundation for Research in Ophthalmology, University of California San Francisco, San Francisco, California, United States of America
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: .
| |
Collapse
|
42
|
Kanan Y, Brobst D, Han Z, Naash MI, Al-Ubaidi MR. Fibulin 2, a tyrosine O-sulfated protein, is up-regulated following retinal detachment. J Biol Chem 2014; 289:13419-33. [PMID: 24692557 DOI: 10.1074/jbc.m114.562157] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Retinal detachment is the physical separation of the retina from the retinal pigment epithelium. It occurs during aging, trauma, or during a variety of retinal disorders such as age-related macular degeneration, diabetic retinopathy, retinopathy of prematurity, or as a complication following cataract surgery. This report investigates the role of fibulin 2, an extracellular component, in retinal detachment. A major mechanism for detachment resolution is enhancement of cellular adhesion between the retina and the retinal pigment epithelium and prevention of its cellular migration. This report shows that fibulin 2 is mainly present in the retinal pigment epithelium, Bruch membrane, choriocapillary, and to a lesser degree in the retina. In vitro studies revealed the presence of two isoforms for fibulin 2. The small isoform is located inside the cell, and the large isoform is present inside and outside the cells. Furthermore, fibulin 2 is post-translationally modified by tyrosine sulfation, and the sulfated isoform is present outside the cell, whereas the unsulfated pool is internally located. Interestingly, sulfated fibulin 2 significantly reduced the rate of cellular growth and migration. Finally, levels of fibulin 2 dramatically increased in the retinal pigment epithelium following retinal detachment, suggesting a direct role for fibulin 2 in the re-attachment of the retina to the retinal pigment epithelium. Understanding the role of fibulin 2 in enhancing retinal attachment is likely to help improve the current therapies or allow the development of new strategies for the treatment of this sight-threatening condition.
Collapse
Affiliation(s)
- Yogita Kanan
- From the Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | | | | | | | | |
Collapse
|
43
|
The link between intravitreal antivascular endothelial growth factor injections and glaucoma. Curr Opin Ophthalmol 2014; 25:127-33. [PMID: 24406814 DOI: 10.1097/icu.0000000000000036] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW To summarize the reports of both transient and sustained elevation in intraocular pressure (IOP) associated with intravitreal injections of antivascular endothelial growth factor (anti-VEGF) agents and to review the possible mechanisms for these findings. RECENT FINDINGS Transient elevation in IOP is common after intravitreal injection of anti-VEGF agents. Sustained IOP elevation is less commonly seen but can require medical and/or surgical intervention. The mechanism for sustained IOP elevation is not well understood but has been attributed to trabecular meshwork injury from repeated injections, a potential toxic or inflammatory reaction after exposure to the biologic agents and/or vehicle, or mechanical blockade of the trabecular meshwork by protein aggregates or contaminant particles associated with packaging and injection techniques, among other potential causes. SUMMARY Intravitreal anti-VEGF injections are commonly used to treat neovascular diseases of the eye. Although they have a favorable side-effect profile, their use can be associated with both transient and sustained elevation in IOP. Further research is necessary to determine the cause of these findings.
Collapse
|
44
|
O'Brien ET, Wang Y, Ying H, Yue BYJT. Differential expression of genes in cells cultured from juxtacanalicular trabecular meshwork and Schlemm's canal. J Ocul Pharmacol Ther 2014; 30:291-9. [PMID: 24611521 DOI: 10.1089/jop.2013.0189] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
PURPOSE The purpose of this study was to distinguish differences in gene expression between cells cultured from the juxtacanalicular trabecular meshwork (JCTM) and those from Schlemm's canal (SC), to gain clues to differences between those cell types, and to add to our baseline knowledge of gene expression differences in these cell types for later comparison between cells from nonprimary open-angle glaucoma (POAG) and POAG outflow tissues. METHODS A set of JCTM and SC cells was cultured from each of 2 donor eyes by an explant method, grown to passage 3, and frozen in liquid nitrogen. The cells were thawed, total RNA was extracted, and the probes made from total RNAs were hybridized to MICROMAX human cDNA microarray slides in 2 separate trials. Differentially expressed genes were analyzed using PubMed, Prosite, and IPA software, and the expression of several of the genes including intercellular adhesion molecule-1 (ICAM-1), tenascin, and β-spectrin was assessed by immunofluorescence. RESULTS Schlemm's canal cells differentially expressed ICAM-1, spectrin, complement, fibulin-1, and several genes consistent with an endothelial origin in both arrays, while the JCTM cells more often overexpressed genes consistent with contractile, matrix function, and neural character. At the same time, many genes highly expressed in the first array were not highly overexpressed in the second. One highly overexpressed gene in the JCTM in both arrays, that for heparan sulfate 3-O-sulfotransferase-1 precursor, is thought to be somewhat unique, and could affect the glycosaminoglycan functionality in the extracellular matrix (ECM). CONCLUSIONS We found generally good agreement between the 2 array trials, but some contradictions as well. Many of the genes overexpressed in each cell type had been described in earlier work, but several were new. Tables of genes, grouped by cellular function, and the complete datasets are provided for the development of new hypotheses.
Collapse
Affiliation(s)
- E Timothy O'Brien
- 1 Department of Physics and Astronomy, University of North Carolina , Chapel Hill, North Carolina
| | | | | | | |
Collapse
|
45
|
Integrins in trabecular meshwork and optic nerve head: possible association with the pathogenesis of glaucoma. BIOMED RESEARCH INTERNATIONAL 2013; 2013:202905. [PMID: 23586020 PMCID: PMC3613054 DOI: 10.1155/2013/202905] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 02/07/2013] [Indexed: 02/02/2023]
Abstract
Integrins are a family of membrane-spanning proteins that are important receptors for cell adhesion to extracellular matrix proteins. They also provide connections between the extracellular environment and intracellular cytoskeletons and are responsible for activation of many intracellular signaling pathways. In vitro and in vivo data strongly indicate that integrin-mediated signaling events can modulate the organization of the actin cytoskeleton in trabecular meshwork (TM) cells and are associated with astrocyte migration and microglia activation of the optic nerve head in patients with primary open angle glaucoma. Consequently, increase in resistance in the TM outflow pathways and remodeling of the optic nerve head occur, which in turn increases intraocular pressure (IOP), adds additional mechanical stress and strain to optic nerve axons, and accelerates damage of axons initially caused by optic nerve head remodeling. Integrins appear to be ideal candidates for translating physical stress and strain into cellular responses known to occur in glaucomatous optic neuropathy.
Collapse
|
46
|
Pattabiraman PP, Epstein DL, Rao PV. Regulation of Adherens Junctions in Trabecular Meshwork Cells by Rac GTPase and their influence on Intraocular Pressure. ACTA ACUST UNITED AC 2013; 1. [PMID: 24932460 DOI: 10.13188/2334-2838.1000002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Intercellular adherens junctions and cell-extracellular matrix interactions are presumed to influence aqueous humor (AH) drainage via the conventional route, however, their direct role in modulation of intraocular pressure (IOP) is not well understood. Here, we investigated the role of Rac GTPase signaling in basal and growth factor-induced formation of adherens junctions in human trabecular meshwork (HTM) cells as compared to human umbilical vascular endothelial cells, and evaluated the effects of inhibition of Rac GTPase activity on IOP in rabbits. Expression of a constitutively active Rac1 GTPase or treatment with platelet derived growth factor (PDGF), a known activator of Rac GTPase, induced formation of β-catenin-based adherens junctions, actin cytoskeletal reorganization and membrane ruffle in HTM cells. In contrast, treatment of HTM cells with inhibitors of Rac GTPase caused cell-cell separation, a decrease in adherens junctions, and reorganization of actin stress fibers to the cell cortical regions and focal adhesion to the cell leading edges. Both, constitutively active Rac1 and PDGF stimulated generation of Reactive Oxygen Species (ROS) in HTM cells, and ROS were found to increase adherens junction formation and transendothelial electrical resistance (TEER) in HTM cells. Topical application of Rac GTPase inhibitors (EHT1864 and NSC23766), however, only marginally influenced IOP in rabbit eyes. Taken together, these data reveal that while Rac GTPase signaling plays a significant role in regulation of adherens junctions, ROS production and TEER in cells of the AH outflow pathway, Rac inhibitors showed only a marginal influence on IOP in live rabbits.
Collapse
Affiliation(s)
| | - David L Epstein
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA 27710
| | | |
Collapse
|
47
|
Singh RSJ, Kim JE. Ocular Hypertension Following Intravitreal Anti-vascular Endothelial Growth Factor Agents. Drugs Aging 2012. [DOI: 10.1007/s40266-012-0031-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
|
48
|
Sano K, Katsuta O, Shirae S, Kubota Y, Ema M, Suda T, Nakamura M, Hirashima M. Flt1 and Flk1 mediate regulation of intraocular pressure and their double heterozygosity causes the buphthalmia in mice. Biochem Biophys Res Commun 2012; 420:422-7. [PMID: 22426483 DOI: 10.1016/j.bbrc.2012.03.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 03/02/2012] [Indexed: 10/28/2022]
Abstract
Flt1 and Flk1 are receptor tyrosine kinases for vascular endothelial growth factor-A which play a crucial role in physiological and pathological angiogenesis. To study genetic interaction between the Flt1 and Flk1 genes, we crossed between Flt1 and Flk1 heterozygous (Flt1(+/-) and Flk1(+/-)) mice. We found that Flt1; Flk1 double heterozygous (Flt1(+/-); Flk1(+/-)) mice showed enlarged eyes similar to the buphthalmia detected in human congenital glaucoma with elevation of intraocular pressure (IOP). Actually, IOP was elevated in Flt1(+/-); Flk1(+/-) mice and also in Flt1 or Flk1 single heterozygous mice. However, none of these mutants showed hallmarks of glaucoma such as ganglion cell death and excavation of optic disc. To clarify the pathological causes for enlarged eyes and elevated IOP, we investigate the mice from matings between Flt1(+/-) and Flk1(+/-) mice. Flt1(+/-) mice showed enlarged Schlemm's canal and disordered collagen fibers in the sclera, whereas Flk1(+/-) mice showed atrophied choriocapillaris in the choroid. These tissues are a part of the main outflow and alternative uveoscleral outflow pathway of the aqueous humor, suggesting that these pathological changes found in Flt1(+/-) and Flk1(+/-) mice are associated with the buphthalmia in Flt1(+/-); Flk1(+/-) mice.
Collapse
Affiliation(s)
- Keigo Sano
- Division of Vascular Biology, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan
| | | | | | | | | | | | | | | |
Collapse
|
49
|
Zhou EH, Krishnan R, Stamer WD, Perkumas KM, Rajendran K, Nabhan JF, Lu Q, Fredberg JJ, Johnson M. Mechanical responsiveness of the endothelial cell of Schlemm's canal: scope, variability and its potential role in controlling aqueous humour outflow. J R Soc Interface 2011; 9:1144-55. [PMID: 22171066 DOI: 10.1098/rsif.2011.0733] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Primary open-angle glaucoma is associated with elevated intraocular pressure, which in turn is believed to result from impaired outflow of aqueous humour. Aqueous humour outflow passes mainly through the trabecular meshwork (TM) and then through pores formed in the endothelium of Schlemm's canal (SC), which experiences a basal-to-apical pressure gradient. This gradient dramatically deforms the SC endothelial cell and potentially contributes to the formation of those pores. However, mechanical properties of the SC cell are poorly defined. Using optical magnetic twisting cytometry and traction force microscopy, here we characterize the mechanical properties of primary cultures of the human SC cell, and for the first time, the scope of their changes in response to pharmacological agents that are known to modulate outflow resistance. Lysophosphatidic acid, sphingosine-1-phosphate (S1P) and thrombin caused an increase in cell stiffness by up to 200 per cent, whereas in most cell strains, exposure to latrunculin A, isoproterenol, dibutryl cyclic-AMP or Y-27632 caused a decrease in cell stiffness by up to 80 per cent, highlighting that SC cells possess a remarkably wide contractile scope. Drug responses were variable across donors. S1P, for example, caused 200 per cent stiffening in one donor strain but only 20 per cent stiffening in another. Isoproterenol caused dose-dependent softening in three donor strains but little or no response in two others, a finding mirrored by changes in traction forces and consistent with the level of expression of β(2)-adrenergic receptors. Despite donor variability, those drugs that typically increase outflow resistance systematically caused cell stiffness to increase, while in most cases, those drugs that typically decrease outflow resistance caused cell stiffness to decrease. These findings establish the endothelial cell of SC as a reactive but variable mechanical component of the aqueous humour outflow pathway. Although the mechanism and locus of increased outflow resistance remain unclear, these data suggest the SC endothelial cell to be a modulator of outflow resistance.
Collapse
Affiliation(s)
- E H Zhou
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|