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The LRRC8-mediated volume-regulated anion channel is altered in glaucoma. Sci Rep 2019; 9:5392. [PMID: 30931966 PMCID: PMC6443673 DOI: 10.1038/s41598-019-41524-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 03/04/2019] [Indexed: 01/07/2023] Open
Abstract
Regulation of cellular volume is an essential process to balance volume changes during cell proliferation and migration or when intracellular osmolality increases due to transepithelial transport. We previously characterized the key role of volume-regulated anion channels (VRAC) in the modulation of the volume of trabecular meshwork (TM) cells and, in turn, the aqueous humour (AH) outflow from the eye. The balance between the secretion and the drainage of AH determines the intraocular pressure (IOP) that is the major casual risk factor for glaucoma. Glaucoma is an ocular disease that causes irreversible blindness due to the degeneration of retinal ganglion cells. The recent identification of Leucine-Rich Repeat-Containing 8 (LRRC8A-E) proteins as the molecular components of VRAC opens the field to elucidate their function in the physiology of TM and glaucoma. Human TM cells derived from non-glaucomatous donors and from open-angle glaucoma patients were used to determine the expression and the functional activity of LRRC8-mediated channels. Expression levels of LRRC8A-E subunits were decreased in HTM glaucomatous cells compared to normotensive HTM cells. Consequently, the activity of VRAC currents and volume regulation of TM cells were significantly affected. Impaired cell volume regulation will likely contribute to altered aqueous outflow and intraocular pressure.
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Tellios N, Feng M, Chen N, Liu H, Tellios V, Wang M, Li X, Chang CA, Hutnik C. Mechanical stretch upregulates connexin43 in human trabecular meshwork cells. Clin Exp Ophthalmol 2019; 47:787-794. [PMID: 30816600 DOI: 10.1111/ceo.13492] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 02/17/2019] [Accepted: 02/22/2019] [Indexed: 11/28/2022]
Abstract
BACKGROUND Primary open angle glaucoma (POAG) patients have hallmark increases in intraocular pressure (IOP) and noted dysfunction of the trabecular meshwork (TM). Connexin43 (Cx43) is a gap junction widely expressed on the TM that is important for intercellular communication. The human gene is known as gap junction alpha-1 (GJA1). Since the role of Cx43 in the TM is not fully understood, we set out to determine the effect of excess mechanical stretch on cultured human trabecular meshwork cells (hTMCs) and to specifically investigate the effect of stretch on Cx43 expression and function. METHODS Primary hTMCs were cultured and subjected to 48 hours of 15% cyclic mechanical stretch at a frequency of 1 Hz. Levels of apoptosis and necrosis secondary to stretch were investigated using colorimetric assays. The effect of stretch on gap junction Cx43 and GJA1 was investigated by RT-PCR, immunoblotting and immunofluorescence. The migration of Lucifer Yellow dye was used to assess intercellular communication. RESULTS Stretch significantly increased the rates of apoptosis and necrosis in hTMCs. The increased rate of injury in stretched hTMCs was further associated with significant upregulation of GJA1 mRNA and Cx43 protein. Upregulation of Cx43 protein was concomitant to increased intercellular communication. CONCLUSIONS We have shown stretch to increase GJA1 gene and Cx43 protein expression, as well as intercellular communication. We have further shown stretch to be injurious to hTMCs. Upregulation of Cx43 in the hTM subsequent to stretch is a novel finding, which may be useful in elucidating the mechanism of TM injury in POAG patients.
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Affiliation(s)
| | - Mary Feng
- Department of Ophthalmology, Ivey Eye Institute, St. Joseph's Healthcare, London, Ontario, Canada
| | - Nancy Chen
- Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Hong Liu
- Lawson Health Research Institute, St. Joseph's Healthcare, London, Ontario, Canada
| | - Vasiliki Tellios
- Department of Neuroscience, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Mary Wang
- Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Xiangji Li
- Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Caitlin A Chang
- Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Cindy Hutnik
- Department of Ophthalmology, Ivey Eye Institute, St. Joseph's Healthcare, London, Ontario, Canada.,Lawson Health Research Institute, St. Joseph's Healthcare, London, Ontario, Canada.,Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
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53
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Ho LTY, Skiba N, Ullmer C, Rao PV. Lysophosphatidic Acid Induces ECM Production via Activation of the Mechanosensitive YAP/TAZ Transcriptional Pathway in Trabecular Meshwork Cells. Invest Ophthalmol Vis Sci 2019; 59:1969-1984. [PMID: 29677358 PMCID: PMC5896423 DOI: 10.1167/iovs.17-23702] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Purpose Lysophosphatidic acid (LPA), a bioactive lipid, has been shown to increase resistance to aqueous humor outflow (AH) through the trabecular meshwork (TM). The molecular basis for this response of the TM to LPA, however, is not completely understood. In this study, we explored the possible involvement of mechanosensitive Yes-associated protein (YAP) and its paralog, transcriptional coactivator with PDZ-binding domain (TAZ), transcriptional activation in extracellular matrix (ECM) production by LPA-induced contractile activity in human TM cells (HTM). Methods The responsiveness of genes encoding LPA receptors (LPARs), LPA hydrolyzing lipid phosphate phosphatases (LPPs), and the LPA-generating autotaxin (ATX) to cyclic mechanical stretch in HTM cells, was evaluated by RT-quantitative (q)PCR. The effects of LPA and LPA receptor antagonists on actomyosin contractile activity, activation of YAP/TAZ, and levels of connective tissue growth factor (CTGF), and Cyr61 and ECM proteins in HTM cells were determined by immunoblotting, mass spectrometry, and immunofluorescence analyses. Results Cyclic mechanical stretch significantly increased the expression of several types of LPARs, LPP1, and ATX in HTM cells. LPA and LPA receptor–dependent contractile activity led to increases in both, the protein levels and activation of YAP/TAZ, and increased the levels of CTGF, Cyr61, α-smooth muscle actin (α–SMA), and ECM proteins in HTM cells. Conclusions The results of this study reveal that LPA and its receptors stimulate YAP/TAZ transcriptional activity in HTM cells by modulating cellular contractile tension, and augment expression of CTGF that in turn leads to increased production of ECM. Therefore, YAP/TAZ-induced increases in CTGF and ECM production could be an important molecular mechanism underlying LPA-induced resistance to AH outflow and ocular hypertension.
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Affiliation(s)
- Leona T Y Ho
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States
| | - Nikolai Skiba
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States
| | - Christoph Ullmer
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland
| | - Ponugoti Vasantha Rao
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States.,Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina, United States
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Abstract
Many diseases are related to age, among these neurodegeneration is particularly important. Alzheimer's disease Parkinson's and Glaucoma have many common pathogenic events including oxidative damage, Mitochondrial dysfunction, endothelial alterations and changes in the visual field. These are well known in the case of glaucoma, less in the case of neurodegeneration of the brain. Many other molecular aspects are common, such as the role of endoplasmic reticulum autophagy and neuronal apoptosis while others have been neglected due to lack of space such as inflammatory cytokine or miRNA. Moreover, the loss of specific neuronal populations, the induction of similar mechanisms of cell injury and the deposition of protein aggregates in specific anatomical areas are very similar events between these diseases. Intracellular and/or extracellular accumulation of protein aggregates is a key feature of many neurodegenerative disorders. The existence of abnormal protein aggregates has been documented in the RGCs of glaucomatous patients such as the anomalous Tau protein or the β-amyloid accumulations. Intra-cell catabolic processes also appear to be common in both glaucoma and neurodegeneration. They also help us to understand how the basis between these diseases is common and how the visual aspects can be a serious problem for those who are affected.
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Affiliation(s)
- Sergio Claudio Saccà
- Department of Head/Neck Pathologies, St Martino Hospital, Ophthalmology Unit, Genoa, Italy.
| | - Carlo Alberto Cutolo
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Maternal and Child Science, University of Genoa, Policlinico San Martino Hospital, Eye Clinic Genoa, Genoa, Italy
| | - Tommaso Rossi
- Department of Head/Neck Pathologies, St Martino Hospital, Ophthalmology Unit, Genoa, Italy
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55
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Yarishkin O, Phuong TTT, Bretz CA, Olsen KW, Baumann JM, Lakk M, Crandall A, Heurteaux C, Hartnett ME, Križaj D. TREK-1 channels regulate pressure sensitivity and calcium signaling in trabecular meshwork cells. J Gen Physiol 2018; 150:1660-1675. [PMID: 30446509 PMCID: PMC6279358 DOI: 10.1085/jgp.201812179] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 10/26/2018] [Indexed: 12/31/2022] Open
Abstract
The trabecular meshwork (TM) plays a fundamental role in intraocular pressure regulation, but its mechanotransduction pathway is poorly understood. Yarishkin et al. show that the mechanosensing channel TREK-1 regulates TM membrane potential, pressure sensitivity, calcium homeostasis, and impedance. Mechanotransduction by the trabecular meshwork (TM) is an essential component of intraocular pressure regulation in the vertebrate eye. This process is compromised in glaucoma but is poorly understood. In this study, we identify transient receptor potential vanilloid isoform 4 (TRPV4) and TWIK-related potassium channel-1 (TREK-1) as key molecular determinants of TM membrane potential, pressure sensitivity, calcium homeostasis, and transcellular permeability. We show that resting membrane potential in human TM cells is unaffected by “classical” inhibitors of voltage-activated, calcium-activated, and inwardly rectifying potassium channels but is depolarized by blockers of tandem-pore K+ channels. Using gene profiling, we reveal the presence of TREK-1, TASK-1, TWIK-2, and THIK transcripts in TM cells. Pressure stimuli, arachidonic acid, and TREK-1 activators hyperpolarize these cells, effects that are antagonized by quinine, amlodipine, spadin, and short-hairpin RNA–mediated knockdown of TREK-1 but not TASK-1. Activation and inhibition of TREK-1 modulates [Ca2+]TM and lowers the impedance of cell monolayers. Together, these results suggest that tensile homeostasis in the TM may be regulated by balanced, pressure-dependent activation of TRPV4 and TREK-1 mechanotransducers.
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Affiliation(s)
- Oleg Yarishkin
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT
| | - Tam T T Phuong
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT
| | - Colin A Bretz
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT
| | - Kenneth W Olsen
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT
| | - Jackson M Baumann
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT.,Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, UT.,Bioengineering Graduate Program, University of Utah School of Medicine, Salt Lake City, UT
| | - Monika Lakk
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT
| | - Alan Crandall
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT
| | - Catherine Heurteaux
- Institute de Pharmacologie Moléculaire et Cellulaire, CNRS, Valbonne, France
| | - Mary E Hartnett
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT
| | - David Križaj
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT .,Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, UT.,Bioengineering Graduate Program, University of Utah School of Medicine, Salt Lake City, UT.,Department of Neurobiology & Anatomy, University of Utah School of Medicine, Salt Lake City, UT
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56
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Tsukamoto T, Kajiwara K, Nada S, Okada M. Src mediates TGF‐β‐induced intraocular pressure elevation in glaucoma. J Cell Physiol 2018; 234:1730-1744. [DOI: 10.1002/jcp.27044] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 06/25/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Teruhisa Tsukamoto
- Department of Oncogene Research Research Institute for Microbial Diseases, Osaka University Osaka Japan
- New Drug Research Division Ako Research Institute, Otsuka Pharmaceutical Co., Ltd. Ako Japan
| | - Kentaro Kajiwara
- Department of Oncogene Research Research Institute for Microbial Diseases, Osaka University Osaka Japan
| | - Shigeyuki Nada
- Department of Oncogene Research Research Institute for Microbial Diseases, Osaka University Osaka Japan
| | - Masato Okada
- Department of Oncogene Research Research Institute for Microbial Diseases, Osaka University Osaka Japan
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Xin C, Song S, Johnstone M, Wang N, Wang RK. Quantification of Pulse-Dependent Trabecular Meshwork Motion in Normal Humans Using Phase-Sensitive OCT. Invest Ophthalmol Vis Sci 2018; 59:3675-3681. [PMID: 30029254 PMCID: PMC6054426 DOI: 10.1167/iovs.17-23579] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 05/30/2018] [Indexed: 12/23/2022] Open
Abstract
Purpose The purpose of this study was to characterize the pulsatile motion of trabecular meshwork (TM) in normal subjects and demonstrate its changes in accommodation with phase-sensitive optical coherence tomography (PhS-OCT). Methods A new PhS-OCT laboratory prototype was designed to measure pulsatile TM motion in 13 healthy humans. Two sets of images were captured in 10 subjects, first with best corrective refraction and the other with an additional 3.0 diopters of accommodation. In each image, both maximum velocity (MV) and cumulative displacement (CD) in two selected regions of TM, the internal (IMV and ICD) and external (EMV and ECD) region, were measured. Results For all parameters the intraclass correlation coefficient was >0.75. Neither MV nor CD was significantly different between eyes in individual subjects (PIMV = 0.967, PEMV = 0.391, PICD = 0.603, PECD = 0.482). In 26 eyes, with best corrective refraction, the EMV was higher than the IMV (23.9 ± 9.8 vs. 18.9 ± 8.08 μm/s; P = 0.0001), as was the ECD compared with the ICD (0.340 ±0.125 vs. 0.264 ± 0.111 μm; P = 0.000004). With accommodation, MV and CD significantly increased (PIMV = 0.0003, PEMV = 0.0003, PICD = 0.019, and PECD = 0.007), whereas MV and CD in the external region were still larger than those in the internal area (PEMV vs. IMV = 0.009, PECD vs. ICD = 0.023). Conclusions This study demonstrates the differences in TM motion between the internal and external regions of TM and displays its change with accommodation. The findings and good reproducibility suggest PhS-OCT helps to understand TM function in regulation of IOP, and, with further refinements, it may be useful in clinical management of glaucoma.
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Affiliation(s)
- Chen Xin
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Shaozhen Song
- Department of Bioengineering, University of Washington, Seattle, Washington, United States
| | - Murray Johnstone
- Department of Ophthalmology, University of Washington, Seattle, Washington, United States
| | - Ningli Wang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, Washington, United States
- Department of Ophthalmology, University of Washington, Seattle, Washington, United States
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58
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TAVARES-SILVA M, FERREIRA D, CARDOSO S, RAIMUNDO AR, BARBOSA-BREDA J, LEITE-MOREIRA A, ROCHA-SOUSA A. Modulation of Iris Sphincter and Ciliary Muscles by Urocortin 2. Physiol Res 2018. [DOI: 10.33549/physiolres.933646] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Urocortin 2 (UCN2) is a peptide related to corticotropin-releasing factor, capable of activating CRF-R2. Among its multisystemic effects, it has actions in all 3 muscle subtypes. This study’s aim was to determine its potential role in two of the intrinsic eye muscle kinetics. Strips of iris sphincter (rabbit) and ciliary (bovine) muscles were dissected and mounted in isometric force-transducer systems filled with aerated-solutions. Contraction was elicited using carbachol (10-6 M for iris sphincter, 10-5 M for ciliary muscle), prior adding to all testing substances. UCN2 induced relaxation in iris sphincter muscle, being the effect maximal at 10-7 M concentrations (-12.2 % variation vs. control). This effect was abolished with incubation of indomethacin, antisauvagine-30, chelerytrine and SQ22536, but preserved with L-nitro-L-arginine. In carbachol pre-stimulated ciliary muscle, UCN2 (10-5 M) enhanced contraction (maximal effect of 18.2 % increase vs. control). UCN2 is a new modulator of iris sphincter relaxation, dependent of CRF-R2 activation, synthesis of prostaglandins (COX pathway) and both adenylate cyclase and PKC signaling pathways, but independent of nitric oxide production. Regarding ciliary muscle, UCN2 enhances carbachol-induced contraction, in higher doses.
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Affiliation(s)
| | | | | | | | | | | | - A. ROCHA-SOUSA
- Department of Surgery and Physiology, Faculty of Medicine, University of Porto, Portugal
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59
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Wareham LK, Buys ES, Sappington RM. The nitric oxide-guanylate cyclase pathway and glaucoma. Nitric Oxide 2018; 77:75-87. [PMID: 29723581 DOI: 10.1016/j.niox.2018.04.010] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/18/2018] [Accepted: 04/23/2018] [Indexed: 01/12/2023]
Abstract
Glaucoma is a prevalent optic neuropathy characterized by the progressive dysfunction and loss of retinal ganglion cells (RGCs) and their optic nerve axons, which leads to irreversible visual field loss. Multiple risk factors for the disease have been identified, but elevated intraocular pressure (IOP) remains the primary risk factor amenable to treatment. Reducing IOP however does not always prevent glaucomatous neurodegeneration, and many patients progress with the disease despite having IOP in the normal range. There is increasing evidence that nitric oxide (NO) is a direct regulator of IOP and that dysfunction of the NO-Guanylate Cyclase (GC) pathway is associated with glaucoma incidence. NO has shown promise as a novel therapeutic with targeted effects that: 1) lower IOP; 2) increase ocular blood flow; and 3) confer neuroprotection. The various effects of NO in the eye appear to be mediated through the activation of the GC- guanosine 3:5'-cyclic monophosphate (cGMP) pathway and its effect on downstream targets, such as protein kinases and Ca2+ channels. Although NO-donor compounds are promising as therapeutics for IOP regulation, they may not be ideal to harness the neuroprotective potential of NO signaling. Here we review evidence that supports direct targeting of GC as a novel pleiotrophic treatment for the disease, without the need for direct NO application. The identification and targeting of other factors that contribute to glaucoma would be beneficial to patients, particularly those that do not respond well to IOP-dependent interventions.
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Affiliation(s)
- Lauren K Wareham
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | | | - Rebecca M Sappington
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA.
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60
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Wang K, Li G, Read AT, Navarro I, Mitra AK, Stamer WD, Sulchek T, Ethier CR. The relationship between outflow resistance and trabecular meshwork stiffness in mice. Sci Rep 2018; 8:5848. [PMID: 29643342 PMCID: PMC5895808 DOI: 10.1038/s41598-018-24165-w] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 03/26/2018] [Indexed: 11/25/2022] Open
Abstract
It has been suggested that common mechanisms may underlie the pathogenesis of primary open-angle glaucoma (POAG) and steroid-induced glaucoma (SIG). The biomechanical properties (stiffness) of the trabecular meshwork (TM) have been shown to differ between POAG patients and unaffected individuals. While features such as ocular hypertension and increased outflow resistance in POAG and SIG have been replicated in mouse models, whether changes of TM stiffness contributes to altered IOP homeostasis remains unknown. We found that outer TM was stiffer than the inner TM and, there was a significant positive correlation between outflow resistance and TM stiffness in mice where conditions are well controlled. This suggests that TM stiffness is intimately involved in establishing outflow resistance, motivating further studies to investigate factors underlying TM biomechanical property regulation. Such factors may play a role in the pathophysiology of ocular hypertension. Additionally, this finding may imply that manipulating TM may be a promising approach to restore normal outflow dynamics in glaucoma. Further, novel technologies are being developed to measure ocular tissue stiffness in situ. Thus, the changes of TM stiffness might be a surrogate marker to help in diagnosing altered conventional outflow pathway function if those technologies could be adapted to TM.
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Affiliation(s)
- Ke Wang
- Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, 30332, United States of America
| | - Guorong Li
- Department of Ophthalmology, Duke University, Durham, North Carolina, 27708, United States of America
| | - A Thomas Read
- Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, 30332, United States of America
| | - Iris Navarro
- Department of Ophthalmology, Duke University, Durham, North Carolina, 27708, United States of America
| | - Ashim K Mitra
- School of Pharmacy, University of Missouri-Kansas City, Kansas City, Missouri, 64110, United States of America
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina, 27708, United States of America
| | - Todd Sulchek
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, 30332, United States of America
| | - C Ross Ethier
- Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, 30332, United States of America. .,George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, 30332, United States of America.
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61
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Impact of the clinical use of ROCK inhibitor on the pathogenesis and treatment of glaucoma. Jpn J Ophthalmol 2018; 62:109-126. [DOI: 10.1007/s10384-018-0566-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 01/23/2018] [Indexed: 12/31/2022]
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62
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Ohia SE, Njie-Mbye YF, Robinson J, Mitchell L, Mckoy M, Opere CA, Sharif NA. Serotonin-2B/2C Receptors Mediate Bovine Ciliary Muscle Contraction: Role in Intraocular Pressure Regulation. J Ocul Pharmacol Ther 2018; 34:70-75. [PMID: 29364761 DOI: 10.1089/jop.2017.0123] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
PURPOSE To study the pharmacological profile of the serotonin (5-hydroxytryptamine [5-HT]) receptor subtype mediating contractions in bovine isolated ciliary muscles. METHODS Ciliary muscle strips were isolated from bovine eyeballs and mounted in organ baths containing aerated (95% O2, 5% CO2) Krebs buffer solution maintained at 37°C. Each muscle strip was attached at 1 end to a Grass Force-displacement Transducer connected to a Polyview Computer System for recording changes in isometric tension. After an equilibration period, ciliary muscle strips were exposed to selective agonists and antagonists of 5-HT receptors. RESULTS Both selective and nonselective agonists for 5-HT produced concentration-dependent contractions of isolated ciliary muscles with the following rank order of potency: BW723C86>α-methyl-5-HT>MK-212>>8-hydroxy-DPAT>quipazine>R-DOI>>5-HT>>tryptamine. The selective 5-HT2 receptor antagonists, M-100907 (5-HT2A), RS-127445 (5-HT2B), and RS-102221 (5-HT2C), produced noncompetitive inhibition of the contractile effects of selective agonists yielding antagonist potency (pKB) values of 251 ± 27.2 nM (n = 4), 52.5 ± 6.3 nM (n = 4), and 79.4 ± 9.5 nM (n = 4), respectively. CONCLUSION On the basis of the profile of activity of selective agonists and antagonists, we conclude that the 5-HT2B and 5-HT2C receptor subtypes appear to be the predominant serotonin receptors that mediate the contractile action of this amine in bovine isolated ciliary muscles.
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Affiliation(s)
- Sunny E Ohia
- 1 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas
| | - Ya Fatou Njie-Mbye
- 1 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas
| | - Jenaye Robinson
- 1 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas
| | - Leah Mitchell
- 1 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas
| | - Marshalyn Mckoy
- 2 Department of Basic Medical Sciences, Pharmacology Section, University of the West Indies , Kingston, Jamaica
| | - Catherine A Opere
- 3 Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Creighton University , Omaha, Nebraska
| | - Naj A Sharif
- 1 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas.,4 Department of Pharmaceutical and Environmental Health Sciences, College of Pharmacy and Health Sciences, Texas Southern University , Houston, Texas
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Zoroquiain P, Mastromonaco C, Balaszi M, Lasiste J, Aldrees S, Saheb N, Burnier MN. Histopathological trabecular meshwork remodeling after cataract surgery detected with an advanced image analyzer. J Cataract Refract Surg 2018; 44:98-102. [DOI: 10.1016/j.jcrs.2017.09.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 08/29/2017] [Accepted: 09/05/2017] [Indexed: 10/17/2022]
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Mechanism of the reconstruction of aqueous outflow drainage. SCIENCE CHINA-LIFE SCIENCES 2017; 61:534-540. [PMID: 29282607 DOI: 10.1007/s11427-017-9140-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 11/20/2017] [Indexed: 10/18/2022]
Abstract
Glaucoma is the leading cause of irreversible blindness worldwide. The reconstruction of aqueous outflow drainage (RAOD) has recently been proposed to aid in restoring aqueous outflow drainage in primary open-angle glaucoma. However, the mechanism of RAOD remains to be fully understood. Based on literature review and research studies, the potential mechanisms of RAOD are the following: (i) Circumferential dilation of the Schlemm's canal (SC) and surrounding collector channels. (ii) Instant formation of microcracks through RAOD procedures. (iii) Formation of more pores, and local detachment between the SC endothelium (SCE) and basement membrane. (iv) Activation of stem cells by constant mechanical stress caused by the tensional suture placed at the anterior part of the SC. (v) Reversal of trabecular meshwork (TM) herniation. (vi) Mobilization of the reserve of the aqueous drainage. (vii) Change of SCE phenotype. (viii) Mechanosensing and mechanotransducing of TM.
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Systems genetics identifies a role for Cacna2d1 regulation in elevated intraocular pressure and glaucoma susceptibility. Nat Commun 2017; 8:1755. [PMID: 29176626 PMCID: PMC5701146 DOI: 10.1038/s41467-017-00837-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 06/28/2017] [Indexed: 12/21/2022] Open
Abstract
Glaucoma is a multi-factorial blinding disease in which genetic factors play an important role. Elevated intraocular pressure is a highly heritable risk factor for primary open angle glaucoma and currently the only target for glaucoma therapy. Our study helps to better understand underlying genetic and molecular mechanisms that regulate intraocular pressure, and identifies a new candidate gene, Cacna2d1, that modulates intraocular pressure and a promising therapeutic, pregabalin, which binds to CACNA2D1 protein and lowers intraocular pressure significantly. Because our study utilizes a genetically diverse population of mice with known sequence variants, we are able to determine that the intraocular pressure-lowering effect of pregabalin is dependent on the Cacna2d1 haplotype. Using human genome-wide association study (GWAS) data, evidence for association of a CACNA2D1 single-nucleotide polymorphism and primary open angle glaucoma is found. Importantly, these results demonstrate that our systems genetics approach represents an efficient method to identify genetic variation that can guide the selection of therapeutic targets. Elevated intraocular pressure (IOP) is a heritable risk factor for primary open angle glaucoma. Using forward mouse genetics, cell biology, pharmacology and human genetic data, the authors identify CACNA2D1 as an IOP risk gene that can be therapeutically targeted by the drug pregabalin in animal models.
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Abstract
Transforming growth factor-β (TGF-β) may play a role in the pathogenesis of primary open-angle glaucoma (POAG). Elevated levels of TGF-β are found in the aqueous humor and in reactive optic nerve astrocytes in patients with glaucoma. In POAG, aqueous humor outflow resistance at the trabecular meshwork (TM) leads to increased intraocular pressure and retinal ganglion cell death. It is hypothesized that TGF-β increases outflow resistance by altering extracellular matrix homeostasis and cell contractility in the TM through interactions with other proteins and signaling molecules. TGF-β may also be involved in damage to the optic nerve head. Current available therapies for POAG focus exclusively on lowering intraocular pressure without addressing extracellular matrix homeostasis processes in the TM. The purpose of this review is to discuss possible therapeutic strategies targeting TGF-β in the treatment of POAG. Herein, we describe the current understanding of the role of TGF-β in POAG pathophysiology, and examine ways TGF-β may be targeted at the levels of production, activation, downstream signaling, and homeostatic regulation.
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67
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Nuzzi R, Tridico F. Glaucoma: Biological Trabecular and Neuroretinal Pathology with Perspectives of Therapy Innovation and Preventive Diagnosis. Front Neurosci 2017; 11:494. [PMID: 28928631 PMCID: PMC5591842 DOI: 10.3389/fnins.2017.00494] [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: 06/09/2017] [Accepted: 08/22/2017] [Indexed: 12/14/2022] Open
Abstract
Glaucoma is a common degenerative disease affecting retinal ganglion cells (RGC) and optic nerve axons, with progressive and chronic course. It is one of the most important reasons of social blindness in industrialized countries. Glaucoma can lead to the development of irreversible visual field loss, if not treated. Diagnosis may be difficult due to lack of symptoms in early stages of disease. In many cases, when patients arrive at clinical evaluation, a severe neuronal damage may have already occurred. In recent years, newer perspective in glaucoma treatment have emerged. The current research is focusing on finding newer drugs and associations or better delivery systems in order to improve the pharmacological treatment and patient compliance. Moreover, the application of various stem cell types with restorative and neuroprotective intent may be found appealing (intravitreal autologous cellular therapy). Advances are made also in terms of parasurgical treatment, characterized by various laser types and techniques. Moreover, recent research has led to the development of central and peripheral retinal rehabilitation (featuring residing cells reactivation and replacement of defective elements), as well as innovations in diagnosis through more specific and refined methods and inexpensive tests.
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Affiliation(s)
- Raffaele Nuzzi
- Eye Clinic Section, Department of Surgical Sciences, University of Turin, Ophthalmic HospitalTurin, Italy
| | - Federico Tridico
- Eye Clinic Section, Department of Surgical Sciences, University of Turin, Ophthalmic HospitalTurin, Italy
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68
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Muralidharan AR, Maddala R, Skiba NP, Rao PV. Growth Differentiation Factor-15-Induced Contractile Activity and Extracellular Matrix Production in Human Trabecular Meshwork Cells. Invest Ophthalmol Vis Sci 2017; 57:6482-6495. [PMID: 27918822 PMCID: PMC5152563 DOI: 10.1167/iovs.16-20671] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Purpose To determine the role and regulation of growth differentiation factor-15 (GDF-15), a TGF-β-related cytokine in human trabecular meshwork (TM) cells in the context of aqueous humor (AH) outflow and IOP. Methods Regulation of expression by external cues, and the distribution and secretion of GDF-15 by human TM primary cell cultures, and the effects of recombinant (r) GDF-15 on TM cell contractile characteristics, actin cytoskeleton, cell adhesion, extracellular matrix (ECM), α-smooth muscle actin (αSMA), SMAD signaling, and gene expression were determined by immunoblot, immunofluorescence, mass spectrometry, cDNA microarray, and real-time quantitative PCR (RT-qPCR) analyses. Results Growth differentiation factor-15, a common constituent of ECM derived from the human TM cells, was confirmed to be distributed throughout the conventional aqueous humor outflow pathway of the human eye. Growth differentiation factor-15 protein levels were significantly increased in human TM cells in response to TGF-β2, dexamethasone, endothelin-1, lysophosphatidic acid, TNF-α, IL-1β treatment, and by cyclic mechanical stretch. Stimulation of human TM cells with rGDF-15 caused a significant increase in the formation of actin stress fibers and focal adhesions, myosin light chain phosphorylation, SMAD signaling, gene expression, and the levels of αSMA and ECM proteins. Conclusions The results of this study, including a robust induction of GDF-15 expression by several external factors known to elevate IOP, and rGDF-15-induced increase in contractility, cell adhesion, and the levels of ECM proteins and αSMA in TM cells, collectively suggest a potential role for GDF-15 in homeostasis and dysregulation of AH outflow and IOP in normal and glaucomatous eyes, respectively.
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Affiliation(s)
| | - Rupalatha Maddala
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States
| | - Nikolai P Skiba
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States
| | - Ponugoti Vasantha Rao
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States 2Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina, United States
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69
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Danford ID, Verkuil LD, Choi DJ, Collins DW, Gudiseva HV, Uyhazi KE, Lau MK, Kanu LN, Grant GR, Chavali VRM, O'Brien JM. Characterizing the "POAGome": A bioinformatics-driven approach to primary open-angle glaucoma. Prog Retin Eye Res 2017; 58:89-114. [PMID: 28223208 PMCID: PMC5464971 DOI: 10.1016/j.preteyeres.2017.02.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 02/03/2017] [Accepted: 02/10/2017] [Indexed: 01/10/2023]
Abstract
Primary open-angle glaucoma (POAG) is a genetically, physiologically, and phenotypically complex neurodegenerative disorder. This study addressed the expanding collection of genes associated with POAG, referred to as the "POAGome." We used bioinformatics tools to perform an extensive, systematic literature search and compiled 542 genes with confirmed associations with POAG and its related phenotypes (normal tension glaucoma, ocular hypertension, juvenile open-angle glaucoma, and primary congenital glaucoma). The genes were classified according to their associated ocular tissues and phenotypes, and functional annotation and pathway analyses were subsequently performed. Our study reveals that no single molecular pathway can encompass the pathophysiology of POAG. The analyses suggested that inflammation and senescence may play pivotal roles in both the development and perpetuation of the retinal ganglion cell degeneration seen in POAG. The TGF-β signaling pathway was repeatedly implicated in our analyses, suggesting that it may be an important contributor to the manifestation of POAG in the anterior and posterior segments of the globe. We propose a molecular model of POAG revolving around TGF-β signaling, which incorporates the roles of inflammation and senescence in this disease. Finally, we highlight emerging molecular therapies that show promise for treating POAG.
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Affiliation(s)
- Ian D Danford
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Lana D Verkuil
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Daniel J Choi
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - David W Collins
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Harini V Gudiseva
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Katherine E Uyhazi
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Marisa K Lau
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Levi N Kanu
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Gregory R Grant
- Department of Genetics, University of Pennsylvania, Philadelphia, PA, USA, Penn Center for Bioinformatics, University of Pennsylvania, Philadelphia, PA, USA
| | - Venkata R M Chavali
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA.
| | - Joan M O'Brien
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
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70
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Chandrawati R, Chang JYH, Reina‐Torres E, Jumeaux C, Sherwood JM, Stamer WD, Zelikin AN, Overby DR, Stevens MM. Localized and Controlled Delivery of Nitric Oxide to the Conventional Outflow Pathway via Enzyme Biocatalysis: Toward Therapy for Glaucoma. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1604932. [PMID: 28221702 PMCID: PMC5400071 DOI: 10.1002/adma.201604932] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 11/21/2016] [Indexed: 05/19/2023]
Abstract
Nitric oxide (NO) is able to lower intraocular pressure (IOP); however, its therapeutic effects on outflow physiology are location- and dose-dependent. A NO delivery platform that directly targets the resistance-generating region of the conventional outflow pathway and locally liberates a controlled dose of NO is reported. An increase in outflow facility (decrease in IOP) is demonstrated in a mouse model.
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Affiliation(s)
- Rona Chandrawati
- Department of MaterialsDepartment of Bioengineering and Institute of Biomedical EngineeringImperial College LondonLondonSW7 2AZUK
| | | | | | - Coline Jumeaux
- Department of MaterialsDepartment of Bioengineering and Institute of Biomedical EngineeringImperial College LondonLondonSW7 2AZUK
| | | | - W. Daniel Stamer
- Department of OphthalmologyDuke University School of MedicineDurhamNC27710USA
| | - Alexander N. Zelikin
- Department of Chemistry and iNANO Interdisciplinary Nanoscience CenterAarhus UniversityAarhus C8000Denmark
| | - Darryl R. Overby
- Department of BioengineeringImperial College LondonLondonSW7 2AZUK
| | - Molly M. Stevens
- Department of MaterialsDepartment of Bioengineering and Institute of Biomedical EngineeringImperial College LondonLondonSW7 2AZUK
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71
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Bermudez JY, Montecchi-Palmer M, Mao W, Clark AF. Cross-linked actin networks (CLANs) in glaucoma. Exp Eye Res 2017; 159:16-22. [PMID: 28238754 DOI: 10.1016/j.exer.2017.02.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/07/2016] [Accepted: 02/22/2017] [Indexed: 12/22/2022]
Abstract
One of the major causes of decreased vision, irreversible vision loss and blindness worldwide is glaucoma. Increased intraocular pressure (IOP) is a major risk factor associated with glaucoma and its molecular mechanisms are not fully understood. The trabecular meshwork (TM) is the primary site of injury in glaucoma, and its dysfunction results in elevated IOP. The glaucomatous TM has increased extracellular matrix deposition as well as cytoskeletal rearrangements referred to as cross-linked actin networks (CLANs) that consist of dome like structures consisting of hubs and spokes. CLANs are thought to play a role in increased aqueous humor outflow resistance and increased IOP by creating stiffer TM cells and tissue. CLANs are inducible by glucocorticoids (GCs) and TGFβ2 in confluent TM cells and TM tissues. The signaling pathways of these induction agents give insight into the possible mechanisms of CLAN formation, but to date, the mechanism of CLANs regulation by these pathways has yet to be determined. Understanding the role CLANs play in IOP elevation and their mechanisms of induction and regulation may lead to novel treatment options to help prevent or intervene in glaucomatous damage to the trabecular meshwork.
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Affiliation(s)
- Jaclyn Y Bermudez
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107, United States.
| | - Michela Montecchi-Palmer
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107, United States.
| | - Weiming Mao
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107, United States.
| | - Abbot F Clark
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107, United States.
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72
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Role of the Rho GTPase/Rho kinase signaling pathway in pathogenesis and treatment of glaucoma: Bench to bedside research. Exp Eye Res 2016; 158:23-32. [PMID: 27593914 DOI: 10.1016/j.exer.2016.08.023] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 08/25/2016] [Accepted: 08/31/2016] [Indexed: 12/14/2022]
Abstract
Glaucoma is a leading cause of irreversible blindness worldwide. Elevated intraocular pressure (IOP) is considered to be a predominant risk factor for primary open angle glaucoma, the most prevalent form of glaucoma. Although the etiological mechanisms responsible for increased IOP are not completely clear, impairment in aqueous humor (AH) drainage through the conventional or trabecular pathway is recognized to be a primary cause in glaucoma patients. Importantly, lowering of IOP has been demonstrated to reduce progression of vision loss and is a mainstay of treatment for all types of glaucoma. Currently however, there are limited therapeutic options available for lowering IOP especially as it relates to enhancement of AH outflow through the trabecular pathway. Towards addressing this challenge, bench and bedside research conducted over the course of the last decade and a half has identified the significance of inhibiting Rho kinase for lowering IOP. Rho kinase is a downstream effector of Rho GTPase signaling that regulates actomyosin dynamics in numerous cell types. Studies from several laboratories have demonstrated that inhibition of Rho kinase lowers IOP via relaxation of the trabecular meshwork which enhances AH outflow. By contrast, activation of Rho GTPase/Rho kinase signaling in the trabecular outflow pathway increases IOP by altering the contractile, cell adhesive and permeability barrier characteristics of the trabecular meshwork and Schlemm's canal tissues, and by influencing extracellular matrix production and fibrotic activity. This article, written in honor of the late David Epstein, MD, summarizes findings from both basic and clinical studies that have been instrumental for recognition of the importance of the Rho/Rho kinase signaling pathway in regulation of AH outflow, and in the development of Rho kinase inhibitors as promising IOP- lowering agents for glaucoma treatment.
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73
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Prasanna G, Li B, Mogi M, Rice DS. Pharmacology of novel intraocular pressure-lowering targets that enhance conventional outflow facility: Pitfalls, promises and what lies ahead? Eur J Pharmacol 2016; 787:47-56. [DOI: 10.1016/j.ejphar.2016.03.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 02/15/2016] [Accepted: 03/01/2016] [Indexed: 12/18/2022]
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74
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Ryskamp DA, Frye AM, Phuong TTT, Yarishkin O, Jo AO, Xu Y, Lakk M, Iuso A, Redmon SN, Ambati B, Hageman G, Prestwich GD, Torrejon KY, Križaj D. TRPV4 regulates calcium homeostasis, cytoskeletal remodeling, conventional outflow and intraocular pressure in the mammalian eye. Sci Rep 2016; 6:30583. [PMID: 27510430 PMCID: PMC4980693 DOI: 10.1038/srep30583] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 07/04/2016] [Indexed: 01/20/2023] Open
Abstract
An intractable challenge in glaucoma treatment has been to identify druggable targets within the conventional aqueous humor outflow pathway, which is thought to be regulated/dysregulated by elusive mechanosensitive protein(s). Here, biochemical and functional analyses localized the putative mechanosensitive cation channel TRPV4 to the plasma membrane of primary and immortalized human TM (hTM) cells, and to human and mouse TM tissue. Selective TRPV4 agonists and substrate stretch evoked TRPV4-dependent cation/Ca2+ influx, thickening of F-actin stress fibers and reinforcement of focal adhesion contacts. TRPV4 inhibition enhanced the outflow facility and lowered perfusate pressure in biomimetic TM scaffolds populated with primary hTM cells. Systemic delivery, intraocular injection or topical application of putative TRPV4 antagonist prodrug analogs lowered IOP in glaucomatous mouse eyes and protected retinal neurons from IOP-induced death. Together, these findings indicate that TRPV4 channels function as a critical component of mechanosensitive, Ca2+-signaling machinery within the TM, and that TRPV4-dependent cytoskeletal remodeling regulates TM stiffness and outflow. Thus, TRPV4 is a potential IOP sensor within the conventional outflow pathway and a novel target for treating ocular hypertension.
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Affiliation(s)
- Daniel A Ryskamp
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Interdepartmental Program in Neuroscience, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Amber M Frye
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Tam T T Phuong
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Oleg Yarishkin
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Andrew O Jo
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Yong Xu
- Department of Medicinal Chemistry, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Monika Lakk
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Interdepartmental Program in Neuroscience, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Anthony Iuso
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Interdepartmental Program in Neuroscience, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Sarah N Redmon
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Interdepartmental Program in Neuroscience, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Balamurali Ambati
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Gregory Hageman
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Center for Translational Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Glenn D Prestwich
- Department of Medicinal Chemistry, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | | | - David Križaj
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Interdepartmental Program in Neuroscience, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Center for Translational Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Department of Neurobiology &Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Department of Bioengineering, University of Utah, Salt Lake City, UT 84112, USA
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75
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Trabecular meshwork stiffness in glaucoma. Exp Eye Res 2016; 158:3-12. [PMID: 27448987 DOI: 10.1016/j.exer.2016.07.011] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 07/15/2016] [Accepted: 07/18/2016] [Indexed: 12/26/2022]
Abstract
Alterations in stiffness of the trabecular meshwork (TM) may play an important role in primary open-angle glaucoma (POAG), the second leading cause of blindness. Specifically, certain data suggest an association between elevated intraocular pressure (IOP) and increased TM stiffness; however, the underlying link between TM stiffness and IOP remains unclear and requires further study. We here first review the literature on TM stiffness measurements, encompassing various species and based on a number of measurement techniques, including direct approaches such as atomic force microscopy (AFM) and uniaxial tension tests, and indirect methods based on a beam deflection model. We also briefly review the effects of several factors that affect TM stiffness, including lysophospholipids, rho-kinase inhibitors, cytoskeletal disrupting agents, dexamethasone (DEX), transforming growth factor-β2 (TGF-β2), nitric oxide (NO) and cellular senescence. We then describe a method we have developed for determining TM stiffness measurement in mice using a cryosection/AFM-based approach, and present preliminary data on TM stiffness in C57BL/6J and CBA/J mouse strains. Finally, we investigate the relationship between TM stiffness and outflow facility between these two strains. The method we have developed shows promise for further direct measurements of mouse TM stiffness, which may be of value in understanding mechanistic relations between outflow facility and TM biomechanical properties.
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76
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Wallace DM, O'Brien CJ. The role of lamina cribrosa cells in optic nerve head fibrosis in glaucoma. Exp Eye Res 2016; 142:102-9. [PMID: 26675406 DOI: 10.1016/j.exer.2014.12.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/26/2014] [Accepted: 12/04/2014] [Indexed: 02/07/2023]
Abstract
Glaucoma is a chronic progressive optic neuropathy. There are extracellular matrix (ECM) changes associated with optic disc cupping in the optic nerve head (ONH) and subsequent visual field defects. The primary risk factor for onset and progression of glaucoma is raised intraocular pressure (IOP). Elevated IOP causes deformation at the ONH specifically at the lamina cribrosa (LC) region where there is also deposition of ECM causing the LC to initially undergo thickening and posterior migration with eventual shearing and collapse of the LC plates leading to a thin fibrotic connective tissue structure/scar. Cells that populate the LC region of the ONH are those cells that are positive for GFAP (the astrocytes) and those negative for GFAP (the LC cells). The LC cell plays an integral role in ECM remodelling producing ECM when exposed to high level mechanical stretch, TGF- β1 and a hypoxic environment.
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Affiliation(s)
- Deborah M Wallace
- UCD School of Medicine and Medical Science, University College Dublin, Belfield, Dublin 4, Ireland; Dept. of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland.
| | - Colm J O'Brien
- UCD School of Medicine and Medical Science, University College Dublin, Belfield, Dublin 4, Ireland; Dept. of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland
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77
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Ko MK, Kim EK, Gonzalez JM, Tan JC. Dose- and time-dependent effects of actomyosin inhibition on live mouse outflow resistance and aqueous drainage tissues. Sci Rep 2016; 6:21492. [PMID: 26884319 PMCID: PMC4756686 DOI: 10.1038/srep21492] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 01/26/2016] [Indexed: 11/13/2022] Open
Abstract
Actomyosin contractility modulates outflow resistance of the aqueous drainage tissues and intraocular pressure, a key pathogenic factor of glaucoma. We established methodology to reliably analyze the effect of latrunculin-B (Lat-B)-induced actin depolymerization on outflow physiology in live mice. A voltage-controlled microperfusion system for delivering drugs and simultaneously analyzing outflow resistance was tested in live C57BL/6 mice. Flow rate and perfusion pressure were reproducible within a coefficient of variation of 2%. Outflow facility for phosphate-buffered saline (0.0027 ± 0.00036 μL/min/mmHg; mean ± SD) and 0.02% ethanol perfusions (Lat-B vehicle; 0.0023 ± 0.0005 μL/min/mmHg) were similar and stable over 2 hours (p > 0.1 for change), indicating absence of a ‘washout’ artifact seen in larger mammals. Outflow resistance changed in graded fashion, decreasing dose- and time-dependently over 2 hours for Lat-B doses of 2.5 μM (p = 0.29), 5 μM (p = 0.039) and 10 μM (p = 0.001). Resulting outflow resistance was about 10 times lower with 10 μM Lat-B than vehicle control. The filamentous actin network was decreased and structurally altered in the ciliary muscle (46 ± 5.6%) and trabecular meshwork (37 ± 8.3%) of treated eyes relative to vehicle controls (p < 0.005; 5 μM Lat-B). Mouse actomyosin contractile mechanisms are important to modulating aqueous outflow resistance, mirroring mechanisms in primates. We describe approaches to reliably probe these mechanisms in vivo.
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Affiliation(s)
- MinHee K Ko
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Eun Kyoung Kim
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Jose M Gonzalez
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - James C Tan
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
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78
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Saccà SC, Gandolfi S, Bagnis A, Manni G, Damonte G, Traverso CE, Izzotti A. The Outflow Pathway: A Tissue With Morphological and Functional Unity. J Cell Physiol 2016; 231:1876-93. [PMID: 26754581 DOI: 10.1002/jcp.25305] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 01/06/2016] [Indexed: 12/17/2022]
Abstract
The trabecular meshwork (TM) plays an important role in high-tension glaucomas. Indeed, the TM is a true organ, through which the aqueous humor flows from the anterior chamber to Schlemm's canal (SC). Until recently, the TM, which is constituted by endothelial-like cells, was described as a kind of passive filter. In reality, it is much more. The cells delineating the structures of the collagen framework of the TM are endowed with a cytoskeleton, and are thus able to change their shape. These cells also have the ability to secrete the extracellular matrix, which expresses proteins and cytokines, and are capable of phagocytosis and autophagy. The cytoskeleton is attached to the nuclear membrane and can, in millionths of a second, send signals to the nucleus in order to alter the expression of genes in an attempt to adapt to biomechanical insult. Oxidative stress, as happens in aging, has a deleterious effect on the TM, leading eventually to cell decay, tissue malfunction, subclinical inflammation, changes in the extracellular matrix and cytoskeleton, altered motility, reduced outflow facility, and (ultimately) increased IOP. TM failure is the most relevant factor in the cascade of events triggering apoptosis in the inner retinal layers, including ganglion cells. J. Cell. Physiol. 231: 1876-1893, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Sergio Claudio Saccà
- Department of Neuroscience and Sense Organs, Ophthalmology Unit, IRCCS San Martino University Hospital, San Martino Hospital, Genoa, Italy
| | - Stefano Gandolfi
- Department of Biological, Biotechnological and Translational Sciences, Ophthalmology Unit, University of Parma, Parma, Italy
| | - Alessandro Bagnis
- Department of Neuroscience and Sense Organs, Eye Clinic, University of Genoa, Genoa, Italy
| | - Gianluca Manni
- Department of Clinical Science and Translational Medicine, University Tor Vergata, Rome, Italy
| | - Gianluca Damonte
- Department of Experimental Medicine, Section of Biochemistry and Center of Excellence for Biomedical Research, University of Genoa, Genoa, Italy
| | - Carlo Enrico Traverso
- Department of Neuroscience and Sense Organs, Eye Clinic, University of Genoa, Genoa, Italy
| | - Alberto Izzotti
- Department of Health Sciences, Mutagenesis Unit, IRCCS San Martino University Hospital, IST National Institute for Cancer Research, University of Genoa, Genoa, Italy
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Influence of Endothelin-1 in Aqueous Humor on Intermediate-Term Trabeculectomy Outcomes. J Ophthalmol 2016; 2016:2401976. [PMID: 26904271 PMCID: PMC4745626 DOI: 10.1155/2016/2401976] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 12/15/2015] [Accepted: 12/21/2015] [Indexed: 11/17/2022] Open
Abstract
Purpose. To investigate whether increased concentrations of ET-1 in aqueous humor of glaucoma patients influences surgical outcome of standard trabeculectomy with Mitomycin C. Methods. Retrospective chart review of 36 glaucoma patients with known ET-1 concentrations who had undergone trabeculectomy with Mitomycin C. Patients were divided into two groups based on their aqueous ET-1 concentration, a below-median (low ET-1) and an above-median (high ET-1) group. Postoperative IOP development, necessity of glaucoma medication, surgical success and complications, postoperative use of antifibrotics (5-FU), and number of additional glaucoma surgeries were compared between the groups. Results. Overall surgical success of trabeculectomy was comparable to published literature (90%, 81%, 76%, and 68% absolute success at 12, 24, 36, and 48 months after surgery). There was no difference between high and low ET-1 group in the postsurgical development of IOP, surgical success rate, or complication rate. There was no difference in postoperative scarring or indirect indicators thereof (e.g., number of 5-FU injections, needlings, suture lyses, or IOP lowering medications). Conclusion. In this set of patients, ET-1 in aqueous humor does not appear to have influenced surgical outcome of trabeculectomy with Mitomycin C. There is no indication of an increased likelihood of bleb fibrosis in patients with increased ET-1 concentrations.
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80
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Giblin JP, Comes N, Strauss O, Gasull X. Ion Channels in the Eye: Involvement in Ocular Pathologies. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2015; 104:157-231. [PMID: 27038375 DOI: 10.1016/bs.apcsb.2015.11.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The eye is the sensory organ of vision. There, the retina transforms photons into electrical signals that are sent to higher brain areas to produce visual sensations. In the light path to the retina, different types of cells and tissues are involved in maintaining the transparency of avascular structures like the cornea or lens, while others, like the retinal pigment epithelium, have a critical role in the maintenance of photoreceptor function by regenerating the visual pigment. Here, we have reviewed the roles of different ion channels expressed in ocular tissues (cornea, conjunctiva and neurons innervating the ocular surface, lens, retina, retinal pigment epithelium, and the inflow and outflow systems of the aqueous humor) that are involved in ocular disease pathophysiologies and those whose deletion or pharmacological modulation leads to specific diseases of the eye. These include pathologies such as retinitis pigmentosa, macular degeneration, achromatopsia, glaucoma, cataracts, dry eye, or keratoconjunctivitis among others. Several disease-associated ion channels are potential targets for pharmacological intervention or other therapeutic approaches, thus highlighting the importance of these channels in ocular physiology and pathophysiology.
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Affiliation(s)
- Jonathan P Giblin
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Nuria Comes
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | | | - Xavier Gasull
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.
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81
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Kim KW, Park SH, Oh DH, Lee SH, Lim KS, Joo K, Chun YS, Chang SI, Min KM, Kim JC. Ribonuclease 5 coordinates signals for the regulation of intraocular pressure and inhibits neural apoptosis as a novel multi-functional anti-glaucomatous strategy. Biochim Biophys Acta Mol Basis Dis 2015; 1862:145-54. [PMID: 26581172 DOI: 10.1016/j.bbadis.2015.11.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 10/15/2015] [Accepted: 11/11/2015] [Indexed: 02/08/2023]
Abstract
Glaucoma is a vision-threatening disorder characterized by progressive death of retinal ganglion cells (RGCs), although little is known about therapeutic milestones. Due to its complex and multifactorial pathogenesis, multipronged therapeutic approach is needed. Angiogenin (ANG), now called ribonuclease (RNase) 5, has been previously known as angiogenic factor and more recently its biologic activity is extended to promoting cell survival via its ribonucleolytic activity. Here, we revealed the defect of ANG in human glaucomatous trabecular meshwork (TM) cells and identified novel multiple functions of ANG as an anti-glaucomatous strategy. ANG was highly expressed in normal eyes and normal TM cells compared to glaucomatous TM cells. ANG induced intraocular pressure (IOP) lowering in rat models of both normal and elevated IOP, and as a possible mechanism, activated Akt-mediated signals for nitric oxide (NO) production, an important regulator of IOP in glaucomatous TM cell. Moreover, we demonstrated ANG-induced production of matrix metalloproteinase (MMP)-1 and -3 and rho-kinase inhibition for TM remodeling. For anti-glaucomatous defense optimization, ANG not only elicited immune-modulative pathways via indolamine 2,3-dioxygenase (IDO) activation in TM cells and suppression of Jurkat T cells, but also rescued neural stem cells (NSCs) from apoptosis induced by glaucomatous stress. These results demonstrate that novel multi-functional effects of ANG may have benefits against glaucoma in ocular tissues.
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Affiliation(s)
- Kyoung Woo Kim
- Department of Ophthalmology, College of Medicine, Chung-Ang University Hospital, Seoul, Republic of Korea; Graduate School of Chung-Ang University, College of Medicine, Seoul, Republic of Korea
| | - Soo Hyun Park
- Department of Ophthalmology, College of Medicine, Chung-Ang University Hospital, Seoul, Republic of Korea
| | - Doo Hwan Oh
- Department of Ophthalmology, College of Medicine, Chung-Ang University Hospital, Seoul, Republic of Korea
| | - Seung Hoon Lee
- Department of Ophthalmology, College of Medicine, Chung-Ang University Hospital, Seoul, Republic of Korea
| | - Kyung Sub Lim
- Department of Ophthalmology, College of Medicine, Chung-Ang University Hospital, Seoul, Republic of Korea
| | - Kwangsic Joo
- Department of Ophthalmology, College of Medicine, Chung-Ang University Hospital, Seoul, Republic of Korea; Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Yeoun Sook Chun
- Department of Ophthalmology, College of Medicine, Chung-Ang University Hospital, Seoul, Republic of Korea
| | - Soo-Ik Chang
- Department of Biochemistry, Chungbuk National University, Cheongju, Chungbuk, Republic of Korea
| | - Kyong-Mi Min
- Department of Biochemistry, Chungbuk National University, Cheongju, Chungbuk, Republic of Korea
| | - Jae Chan Kim
- Department of Ophthalmology, College of Medicine, Chung-Ang University Hospital, Seoul, Republic of Korea.
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82
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Daneshvar R, Amini N. Rho-Associated Kinase Inhibitors: Potential Future Treatments for Glaucoma. J Ophthalmic Vis Res 2015; 9:395-8. [PMID: 26539282 PMCID: PMC4598535 DOI: 10.4103/2008-322x.143384] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Affiliation(s)
- Ramin Daneshvar
- Cornea Research Center, Mashhad University of Medical Sciences, Mashhad, Iran ; Department of Glaucoma, Khatam Eye Hospital, Mashhad, Iran
| | - Nima Amini
- Department of Health Sciences, California State University, Northridge, Los Angeles, CA, USA ; Department of Pathology and Laboratory Medicine, University of California, Davis Medical Center, Sacramento, California, USA
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83
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Pattabiraman PP, Rao PV. Hic-5 Regulates Actin Cytoskeletal Reorganization and Expression of Fibrogenic Markers and Myocilin in Trabecular Meshwork Cells. Invest Ophthalmol Vis Sci 2015; 56:5656-69. [PMID: 26313302 DOI: 10.1167/iovs.15-17204] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
PURPOSE To explore the role of inducible focal adhesion (FA) protein Hic-5 in actin cytoskeletal reorganization, FA formation, fibrogenic activity, and expression of myocilin in trabecular meshwork (TM) cells. METHODS Using primary cultures of human TM (HTM) cells, the effects of various external factors on Hic-5 protein levels, as well as the effects of recombinant Hic-5 and Hic-5 small interfering RNA (siRNA) on actin cytoskeleton, FAs, myocilin, α-smooth muscle actin (αSMA), and collagen-1 were determined by immunofluorescence and immunoblot analyses. RESULTS Hic-5 distributes discretely to the FAs in HTM cells and throughout the TM and Schlemm's canal of the human aqueous humor (AH) outflow pathway. Transforming growth factor-β2 (TGF-β2), endothelin-1, lysophosphatidic acid, hydrogen peroxide, and RhoA significantly increased Hic-5 protein levels in HTM cells in association with reorganization of actin cytoskeleton and FAs. While recombinant Hic-5 induced actin stress fibers, FAs, αv integrin redistribution to the FAs, increased levels of αSMA, collagen-1, and myocilin, Hic-5 siRNA suppressed most of these responses in HTM cells. Hic-5 siRNA also suppressed TGF-β2-induced fibrogenic activity and dexamethasone-induced myocilin expression in HTM cells. CONCLUSIONS Taken together, these results reveal that Hic-5, whose levels were increased by various external factors implicated in elevated intraocular pressure, induces actin cytoskeletal reorganization, FAs, expression of fibrogenic markers, and myocilin in HTM cells. These characteristics of Hic-5 in TM cells indicate its importance in regulation of AH outflow through the TM in both normal and glaucomatous eyes.
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Affiliation(s)
| | - Ponugoti Vasantha Rao
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States 2Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina, United States
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84
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Chen WS, Cao Z, Krishnan C, Panjwani N. Verteporfin without light stimulation inhibits YAP activation in trabecular meshwork cells: Implications for glaucoma treatment. Biochem Biophys Res Commun 2015; 466:221-5. [DOI: 10.1016/j.bbrc.2015.09.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 09/03/2015] [Indexed: 11/28/2022]
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85
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Van de Velde S, De Groef L, Stalmans I, Moons L, Van Hove I. Towards axonal regeneration and neuroprotection in glaucoma: Rho kinase inhibitors as promising therapeutics. Prog Neurobiol 2015; 131:105-19. [PMID: 26093354 DOI: 10.1016/j.pneurobio.2015.06.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 06/08/2015] [Accepted: 06/09/2015] [Indexed: 11/27/2022]
Abstract
Due to a prolonged life expectancy worldwide, the incidence of age-related neurodegenerative disorders such as glaucoma is increasing. Glaucoma is the second cause of blindness, resulting from a slow and progressive loss of retinal ganglion cells (RGCs) and their axons. Up to now, intraocular pressure (IOP) reduction is the only treatment modality by which ophthalmologists attempt to control disease progression. However, not all patients benefit from this therapy, and the pathophysiology of glaucoma is not always associated with an elevated IOP. These limitations, together with the multifactorial etiology of glaucoma, urge the pressing medical need for novel and alternative treatment strategies. Such new therapies should focus on preventing or retarding RGC death, but also on repair of injured axons, to ultimately preserve or improve structural and functional connectivity. In this respect, Rho-associated coiled-coil forming protein kinase (ROCK) inhibitors hold a promising potential to become very prominent drugs for future glaucoma treatment. Their field of action in the eye does not seem to be restricted to IOP reduction by targeting the trabecular meshwork or improving filtration surgery outcome. Indeed, over the past years, important progress has been made in elucidating their ability to improve ocular blood flow, to prevent RGC death/increase RGC survival and to retard axonal degeneration or induce proper axonal regeneration. Within this review, we aim to highlight the currently known capacity of ROCK inhibition to promote neuroprotection and regeneration in several in vitro, ex vivo and in vivo experimental glaucoma models.
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Affiliation(s)
- Sarah Van de Velde
- Laboratory of Ophthalmology, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Lies De Groef
- Neural Circuit Development and Regeneration Research Group, Animal Physiology and Neurobiology Section, Department of Biology, KU Leuven, Leuven, Belgium
| | - Ingeborg Stalmans
- Laboratory of Ophthalmology, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Lieve Moons
- Neural Circuit Development and Regeneration Research Group, Animal Physiology and Neurobiology Section, Department of Biology, KU Leuven, Leuven, Belgium.
| | - Inge Van Hove
- Neural Circuit Development and Regeneration Research Group, Animal Physiology and Neurobiology Section, Department of Biology, KU Leuven, Leuven, Belgium
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86
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M K. Present and New Treatment Strategies in the Management of Glaucoma. Open Ophthalmol J 2015; 9:89-100. [PMID: 26069521 PMCID: PMC4460216 DOI: 10.2174/1874364101509010089] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Revised: 03/30/2015] [Accepted: 03/30/2015] [Indexed: 12/17/2022] Open
Abstract
Glaucoma is a neurodegenerative disease characterized by retinal ganglion cell (RGC) death and axonal loss. It remains a major cause of blindness worldwide. All current modalities of treatment are focused on lowering intraocular pressure (IOP), and it is evident that increased IOP is an important risk factor for progression of the disease. However, it is clear that a significant number of glaucoma patients show disease progression despite of pressure lowering treatments. Much attention has been given to the development of neuroprotective treatment strategies, but the identification of such has been hampered by lack of understanding of the etiology of glaucoma. Hence, in spite of many attempts no neuroprotective drug has yet been clinically approved. Even though neuroprotection is without doubt an important treatment strategy, many glaucoma subjects are diagnosed after substantial loss of RGCs. In this matter, recent approaches aim to rescue RGCs and regenerate axons in order to restore visual function in glaucoma. The present review seeks to provide an overview of the present and new treatment strategies in the management of glaucoma. The treatment strategies are divided into current available glaucoma medications, new pressure lowering targets, prospective neuroprotective interventions, and finally possible neuroregenrative strategies.
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Affiliation(s)
- Kolko M
- Department of Neuroscience and Pharmacology, the Panum Institute, University of Copenhagen, Denmark ; Department of Ophthalmology, Roskilde University Hospital, Copenhagen, Denmark ; Center of Healthy Aging, Department of Cellular and Molecular Medicine, the Panum Institute, University of Copenhagen, Denmark
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87
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The aqueous humor outflow pathways in glaucoma: A unifying concept of disease mechanisms and causative treatment. Eur J Pharm Biopharm 2015; 95:173-81. [PMID: 25957840 DOI: 10.1016/j.ejpb.2015.04.029] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 04/24/2015] [Accepted: 04/29/2015] [Indexed: 12/28/2022]
Abstract
Intraocular pressure (IOP) is the critical risk factor for glaucoma, a neurodegenerative disease and frequent cause of blindness worldwide. As of today, all effective strategies to treat glaucoma aim at lowering IOP. IOP is generated and maintained via the aqueous humor circulation system in the anterior eye. Aqueous humor is secreted by the ciliary processes and exits the eye through the trabecular meshwork (TM) or the uveoscleral outflow pathways. The TM outflow pathways provide resistance to aqueous humor outflow and IOP builds up in response to it. In the normal eye, the resistance is localized in the inner wall region, which comprises the juxtacanalicular connective tissue (JCT) and the inner wall endothelium of Schlemm's canal (SC). Outflow resistance in the inner wall region is lowered through the contraction of the ciliary muscle or the relaxation of contractile myofibroblasts in the posterior part of the TM and the adjacent scleral spur. Patients with primary open-angle glaucoma (POAG), the most frequent form of glaucoma, typically suffer from an abnormally high outflow resistance of the inner wall region. There is increasing evidence that the increase in TM outflow resistance in POAG is the result of a characteristic change in the biological properties of the resident cells in the JCT, which increasingly acquire the phenotype of contractile myofibroblasts. This scenario strengthens simultaneously both their actin cytoskeleton and their directly associated extracellular matrix fibrils, leads to overall stiffening of the tissue, and is modulated by transforming growth factor-β (TGF-β)/connective tissue growth factor (CTGF) signaling. Essentially comparable changes appear to occur in SC endothelial cells in glaucoma. Causative therapy concepts targeting the aqueous outflow pathways in glaucoma should aim at interfering with this process either by attenuating TM or SC stiffness, and/or by modulating TGF-β/CTGF signaling.
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88
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Wallace DM, Pokrovskaya O, O'Brien CJ. The Function of Matricellular Proteins in the Lamina Cribrosa and Trabecular Meshwork in Glaucoma. J Ocul Pharmacol Ther 2015; 31:386-95. [PMID: 25848892 DOI: 10.1089/jop.2014.0163] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
PURPOSE To review the current literature regarding the role of matricellular proteins in glaucoma, specifically in the lamina cribrosa (LC) region of the optic nerve head (ONH) and the trabecular meshwork (TM). METHODS A literature search was performed for published articles describing the expression and function of matricellular proteins such as thrombospondin (TSP), connective tissue growth factor (CTGF), secreted protein acidic and rich in cysteine (SPARC), and periostin in glaucoma. RESULTS In glaucoma, there are characteristic extracellular matrix (ECM) changes associated with optic disc cupping in the ONH and subsequent visual field defects. Matricellular proteins are a family of nonstructural secreted glycoproteins, which enable cells to communicate with their surrounding ECM, including CTGF, also known as CCN2, TSPs, SPARC, periostin, osteonectin, and tenascin-C and -X, and other ECM proteins. Such proteins appear to play a role in fibrosis and increased ECM deposition. Importantly, most are widely expressed in tissues particularly in the TM and ONH, and deficiency of TSP1 and SPARC has been shown to lower intraocular pressure in mouse models of glaucoma through enhanced outflow facility. CONCLUSION This article highlights the role of matricellular proteins in glaucoma pathology. The potential role of these proteins in glaucoma is emerging as some have an association with the pathophysiology of the TM and LC region and might therefore be potential targets for therapeutic intervention in glaucoma.
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Affiliation(s)
- Deborah M Wallace
- 1 School of Medicine and Medical Science, University College Dublin , Dublin, Ireland .,2 Department of Ophthalmology, Mater Misericordiae University Hospital , Dublin, Ireland
| | - Olya Pokrovskaya
- 1 School of Medicine and Medical Science, University College Dublin , Dublin, Ireland .,2 Department of Ophthalmology, Mater Misericordiae University Hospital , Dublin, Ireland
| | - Colm J O'Brien
- 1 School of Medicine and Medical Science, University College Dublin , Dublin, Ireland .,2 Department of Ophthalmology, Mater Misericordiae University Hospital , Dublin, Ireland
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89
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The change in intraocular pressure after pupillary dilation in eyes with pseudoexfoliation glaucoma, primary open angle glaucoma, and eyes of normal subjects. Int Ophthalmol 2015; 35:215-9. [DOI: 10.1007/s10792-014-9935-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Accepted: 03/20/2014] [Indexed: 10/25/2022]
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90
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Intraocular Pressure and the Mechanisms Involved in Resistance of the Aqueous Humor Flow in the Trabecular Meshwork Outflow Pathways. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 134:301-14. [DOI: 10.1016/bs.pmbts.2015.06.007] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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91
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Effect of 0.04% AR-13324, a ROCK, and Norepinephrine Transporter Inhibitor, on Aqueous Humor Dynamics in Normotensive Monkey Eyes. J Glaucoma 2015; 24:51-4. [DOI: 10.1097/ijg.0b013e3182952213] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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92
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RhoA GTPase-induced ocular hypertension in a rodent model is associated with increased fibrogenic activity in the trabecular meshwork. THE AMERICAN JOURNAL OF PATHOLOGY 2014; 185:496-512. [PMID: 25499974 DOI: 10.1016/j.ajpath.2014.10.023] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 09/03/2014] [Accepted: 10/07/2014] [Indexed: 02/08/2023]
Abstract
Ocular hypertension arising from increased resistance to aqueous humor (AH) outflow through the trabecular meshwork is a primary risk factor for open-angle glaucoma, a leading cause of blindness. Ongoing efforts have found little about the molecular and cellular bases of increased resistance to AH outflow through the trabecular meshwork in ocular hypertension patients. To test the hypothesis that dysregulated Rho GTPase signaling and a resulting fibrotic activity within the trabecular meshwork may result in ocular hypertension, we investigated the effects of expressing a constitutively active RhoA GTPase (RhoAV14) in the AH outflow pathway in Sprague-Dawley rats by using lentiviral vector-based gene delivery. Rats expressing RhoAV14 in the iridocorneal angle exhibited a significantly elevated intraocular pressure. Elevated intraocular pressure in the RhoAV14-expressing rats was associated with fibrotic trabecular meshwork and increased levels of F-actin, phosphorylated myosin light chain, α-smooth muscle actin, collagen-1A, and total collagen in the trabecular AH outflow pathway. Most of these changes were ameliorated by topical application of Rho kinase inhibitor. Human autopsy eyes from patients with glaucoma exhibited significant increases in levels of collagen-1A and total collagen in the trabecular AH outflow pathway. Collectively, these observations indicate that increased fibrogenic activity because of dysregulated RhoA GTPase activity in the trabecular AH outflow pathway increases intraocular pressure in a Rho kinase-dependent manner.
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93
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Saccà SC, Pulliero A, Izzotti A. The Dysfunction of the Trabecular Meshwork During Glaucoma Course. J Cell Physiol 2014; 230:510-25. [DOI: 10.1002/jcp.24826] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 09/05/2014] [Indexed: 12/22/2022]
Affiliation(s)
- Sergio Claudio Saccà
- Department of Head/Neck Pathologies; St Martino Hospital; Ophthalmology Unit; Genoa Italy
| | - Alessandra Pulliero
- Department of Health Sciences; Section of Hygiene and Preventive Medicine; University of Genoa; Genoa Italy
| | - Alberto Izzotti
- Department of Health Sciences; Section of Hygiene and Preventive Medicine; University of Genoa; Genoa Italy
- Mutagenesis Unit; IST National Institute for Cancer Research; IRCCS Hospital-University San Martino Company; Genoa Italy
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94
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Atalay E, Tamçelik N, Cicik ME. The Impact of Pupillary Dilation on Intraocular Pressure and Anterior Segment Morphology in Subjects with and without Pseudoexfoliation. Curr Eye Res 2014; 40:646-52. [DOI: 10.3109/02713683.2014.954674] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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95
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Bennett TM, Mackay DS, Siegfried CJ, Shiels A. Mutation of the melastatin-related cation channel, TRPM3, underlies inherited cataract and glaucoma. PLoS One 2014; 9:e104000. [PMID: 25090642 PMCID: PMC4121231 DOI: 10.1371/journal.pone.0104000] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 07/04/2014] [Indexed: 11/19/2022] Open
Abstract
Inherited forms of cataract are a clinically important and genetically heterogeneous cause of visual impairment that usually present at an early age with or without systemic and/or other ocular abnormalities. Here we have identified a new locus for inherited cataract and high-tension glaucoma with variable anterior segment defects, and characterized an underlying mutation in the gene coding for transient receptor potential cation channel, subfamily M, member-3 (TRPM3, melastatin-2). Genome-wide linkage analysis mapped the ocular disease locus to the pericentric region of human chromosome 9. Whole exome and custom-target next-generation sequencing detected a heterozygous A-to-G transition in exon-3 of TRPM3 that co-segregated with disease. As a consequence of alternative splicing this missense mutation was predicted to result in the substitution of isoleucine-to-methionine at codon 65 (c.195A>G; p.I65 M) of TRPM3 transcript variant 9, and at codon 8 (c.24A>G; p.I8 M) of a novel TRPM3 transcript variant expressed in human lens. In both transcript variants the I-to-M substitution was predicted in silico to exert damaging effects on protein function. Furthermore, transient expression studies of a recombinant TRPM3-GFP reporter product predicted that the I-to-M substitution introduced an alternative translation start-site located 89 codons upstream from the native initiator methionine found in eight other TRPM3 transcript variants (1-8). Collectively, these studies have provided the first evidence that TRPM3 is associated with inherited ocular disease in humans, and further provide support for the important role of this cation channel in normal eye development.
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Affiliation(s)
- Thomas M. Bennett
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Donna S. Mackay
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Carla J. Siegfried
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Alan Shiels
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States of America
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96
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Rocha-Sousa A, Pereira-Silva P, Tavares-Silva M, Azevedo-Pinto S, Rodrigues-Araújo J, Pinho S, Avelino A, Falcão-Reis F, Leite-Moreira A. Identification of the ghrelin-GHSR 1 system and its influence in the modulation of induced ocular hypertension in rabbit and rat eyes. Peptides 2014; 57:59-66. [PMID: 24780389 DOI: 10.1016/j.peptides.2014.04.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 04/18/2014] [Accepted: 04/18/2014] [Indexed: 11/23/2022]
Abstract
Recent studies evidenced a decrease in ghrelin's aqueous humor levels in patients with glaucoma. The goal of our investigation was to study the effect of the ghrelin-GHSR-1a system in the modulation of intraocular pressure in acute ocular hypertension models and its expression and distribution in ocular tissues. Two animal models of acute ocular hypertension were used to study the effect of the ghrelin-GHSR-1a system in the modulation of intraocular pressure: the rabbit and the rat. Ocular hypertension was induced by an intravitreal injection of 20% NaCl. Ghrelin or des-acyl ghrelin were delivered subconjunctivally and the intraocular pressure was assessed by a rebound tonometer that was calibrated for each species. In addition, we have studied the influence of nitric oxide and prostaglandins on ghrelin's effect in the rabbit animal model. Finally, we determined by immunofluorescence the expression of ghrelin and GHSR-1 in the rat's ocular tissue. Ghrelin decreased the intraocular pressure in both animal models (maximum decrease: 43.8±12.0% in the rabbit and 29.0±7.46% in the rat). In the rabbit, this effect was blunted in the presence of l-NAME and ketorolac. Des-acyl ghrelin only decreased the intraocular pressure in the rat (maximum decrease: 34.9±8.15%). Ghrelin expression was detected in the ciliary processes and GHSR-1 expression was detected in the trabecular meshwork and ciliary body. The ghrelin-GHSR-1 system is expressed in the anterior segment of the eye. Ghrelin and des-acyl ghrelin are responsible for a hypotensive effect in acute ocular hypertension animal models.
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Affiliation(s)
- A Rocha-Sousa
- Department of Sense Organs, Faculty of Medicine, University of Porto, Porto, Portugal; Department of Ophthalmology, São João Hospital, Porto, Portugal.
| | - P Pereira-Silva
- Department of Physiology and Cardiothoracic Surgery, Faculty of Medicine, University of Porto, Porto, Portugal
| | - M Tavares-Silva
- Department of Physiology and Cardiothoracic Surgery, Faculty of Medicine, University of Porto, Porto, Portugal
| | - S Azevedo-Pinto
- Department of Physiology and Cardiothoracic Surgery, Faculty of Medicine, University of Porto, Porto, Portugal
| | | | - S Pinho
- Department of Physiology and Cardiothoracic Surgery, Faculty of Medicine, University of Porto, Porto, Portugal
| | - A Avelino
- Department of Experimental Biology, Faculty of Medicine, University of Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal
| | - F Falcão-Reis
- Department of Sense Organs, Faculty of Medicine, University of Porto, Porto, Portugal; Department of Ophthalmology, São João Hospital, Porto, Portugal
| | - A Leite-Moreira
- Department of Physiology and Cardiothoracic Surgery, Faculty of Medicine, University of Porto, Porto, Portugal
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97
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Saccà SC, Izzotti A. Focus on molecular events in the anterior chamber leading to glaucoma. Cell Mol Life Sci 2014; 71:2197-218. [PMID: 24142347 PMCID: PMC11113507 DOI: 10.1007/s00018-013-1493-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Revised: 10/03/2013] [Accepted: 10/07/2013] [Indexed: 12/11/2022]
Abstract
Primary open-angle glaucoma is a multifactorial disease that affects the retinal ganglion cells, but currently its therapy is to lower the eye pressure. This indicates a definite involvement of the trabecular meshwork, key region in the pathogenesis of glaucoma. This is the first target of glaucoma, and its functional complexity is a real challenge to search. Its functions are those to allow the outflow of aqueous humor and not the reflux. This article describes the morphological and functional changes that happen in anterior chamber. The "primus movens" is oxidative stress that affects trabecular meshwork, particularly its endothelial cells. In these develops a real mitochondriopaty. This leads to functional impotence, the trabecular meshwork altering both motility and cytoarchitecture. Its cells die by apoptosis, losing barrier functions and altering the aqueous humor outflow. All the morphological alterations occur that can be observed under a microscope. Intraocular pressure rises and the malfunctioning trabecular meshwork endotelial cells express proteins that completely alter the aqueous humor. This is a liquid whose functional proteomics complies with the conditions of the trabecular meshwork. Indeed, in glaucoma, it is possible detect the presence of proteins which testify to what occurs in the anterior chamber. There are six classes of proteins which confirm the vascular endothelium nature of the anterior chamber and are the result of the morphofunctional trabecular meshwork decay. It is possible that, all or in part, these proteins can be used as a signal to the posterior pole.
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Affiliation(s)
- Sergio Claudio Saccà
- Ophthalmology Unit, Department of Head and Neck Pathologies, St Martino Hospital, Viale Benedetto XV, 16132, Genoa, Italy,
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98
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Qiu X, Wu K, Lin X, Liu Q, Ye Y, Yu M. Dexamethasone increases Cdc42 expression in human TM-1 cells. Curr Eye Res 2014; 40:290-9. [PMID: 24871483 DOI: 10.3109/02713683.2014.922191] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE Changes in the cytoskeletal organization of the human trabecular meshwork (HTM) is thought to be responsible for primary open-angle glaucoma (POAG) pathologies. Cdc42 is a Rho GTPase; Rho GTPases are important modulatory agents of the cytoskeleton. This study aimed to investigate the effects of dexamethasone (DEX) on Cdc42 in a transformed HTM cell line, TM-1 to understand the molecular pathologies underlying POAG. METHODS TM-1 cells were cultured in vitro. The cultures were treated with DEX at 10(-6) and 10(-7) M for 1-4 days. Cdc42 was silenced using small interfering RNA (siRNA). The expression levels of Cdc42 in the TM-1 cells were measured using reverse transcription (RT)-PCR, western blotting analysis and immunofluorescence. Its downstream effectors, p21-activated kinase phosphorylation (phospho-PAK) and myosin light chain kinase (MLCK), were measured using western blotting analysis. In addition, the F-actin of TM-1 cells was stained using phalloidin. RESULTS The mRNA and protein levels of Cdc42 showed an increase in TM-1 cells with DEX treatment and a decrease in TM-1 cells transfected with Cdc42 siRNA. Moreover, phospho-PAK levels increased, whereas MLCK levels appeared to decrease, with DEX treatment. The F-actin of DEX-treated TM-1 cells displayed a rearrangement. Cdc42 siRNA decreased the expression of Cdc42 and its related proteins, resulting in an attenuation of the effects of DEX on Cdc42 and F-actin organization in TM-1 cells. CONCLUSIONS DEX increases Cdc42 expression in TM-1. This may represent a potential mechanism of DEX-induced HTM cytoskeletal rearrangement.
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Affiliation(s)
- Xuan Qiu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University , Guangzhou , China
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99
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Buys ES, Potter LR, Pasquale LR, Ksander BR. Regulation of intraocular pressure by soluble and membrane guanylate cyclases and their role in glaucoma. Front Mol Neurosci 2014; 7:38. [PMID: 24904270 PMCID: PMC4032937 DOI: 10.3389/fnmol.2014.00038] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 04/21/2014] [Indexed: 01/01/2023] Open
Abstract
Glaucoma is a progressive optic neuropathy characterized by visual field defects that ultimately lead to irreversible blindness (Alward, 2000; Anderson et al., 2006). By the year 2020, an estimated 80 million people will have glaucoma, 11 million of which will be bilaterally blind. Primary open-angle glaucoma (POAG) is the most common type of glaucoma. Elevated intraocular pressure (IOP) is currently the only risk factor amenable to treatment. How IOP is regulated and can be modulated remains a topic of active investigation. Available therapies, mostly geared toward lowering IOP, offer incomplete protection, and POAG often goes undetected until irreparable damage has been done, highlighting the need for novel therapeutic approaches, drug targets, and biomarkers (Heijl et al., 2002; Quigley, 2011). In this review, the role of soluble (nitric oxide (NO)-activated) and membrane-bound, natriuretic peptide (NP)-activated guanylate cyclases that generate the secondary signaling molecule cyclic guanosine monophosphate (cGMP) in the regulation of IOP and in the pathophysiology of POAG will be discussed.
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Affiliation(s)
- Emmanuel S Buys
- Department of Anesthesia, Critical Care, and Pain Medicine, Anesthesia Center for Critical Care Research, Harvard Medical School, Massachusetts General Hospital Boston, MA, USA
| | - Lincoln R Potter
- Department of Pharmacology, University of Minnesota Medical School Minneapolis, MN, USA
| | - Louis R Pasquale
- Department of Ophthalmology, Glaucoma Service Mass Eye and Ear Infirmary and Channing Division of Network Medicine, Harvard Medical School, Brigham and Women's Hospital Boston, MA, USA
| | - Bruce R Ksander
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Schepens Eye Research Institute, Harvard Medical School Boston, MA, USA
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100
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Pattabiraman PP, Maddala R, Rao PV. Regulation of plasticity and fibrogenic activity of trabecular meshwork cells by Rho GTPase signaling. J Cell Physiol 2014; 229:927-42. [PMID: 24318513 DOI: 10.1002/jcp.24524] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 12/02/2013] [Indexed: 12/29/2022]
Abstract
Glaucoma, a prevalent blinding disease is commonly associated with increased intraocular pressure due to impaired aqueous humor (AH) drainage through the trabecular meshwork (TM). Although increased TM tissue contraction and stiffness in association with accumulation of extracellular matrix (ECM) are believed to be partly responsible for increased resistance to AH outflow, the extracellular cues and intracellular mechanisms regulating TM cell contraction and ECM production are not well defined. This study tested the hypothesis that sustained activation of Rho GTPase signaling induced by lysophosphatidic acid (LPA), TGF-β, and connective tissue growth factor (CTGF) influences TM cell plasticity and fibrogenic activity which may eventually impact resistance to AH outflow. Various experiments performed using human TM cells revealed that constitutively active RhoA (RhoAV14), TGF-β2, LPA, and CTGF significantly increase the levels and expression of Fibroblast Specific Protein-1 (FSP-1), α-smooth muscle actin (αSMA), collagen-1A1 and secretory total collagen, as determined by q-RT-PCR, immunofluorescence, immunoblot, flow cytometry and the Sircol assay. Significantly, these changes appear to be mediated by Serum Response Factor (SRF), myocardin-related transcription factor (MRTF-A), Slug, and Twist-1, which are transcriptional regulators known to control cell plasticity, myofibroblast generation/activation and fibrogenic activity. Additionally, the Rho kinase inhibitor-Y27632 and anti-fibrotic agent-pirfenidone were both found to suppress the TGF-β2-induced expression of αSMA, FSP-1, and collagen-1A1. Taken together, these observations demonstrate the significance of RhoA/Rho kinase signaling in regulation of TM cell plasticity, fibrogenic activity, and myofibroblast activation, events with potential implications for the pathobiology of elevated intraocular pressure in glaucoma patients.
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