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Zhu J, Chen H, Wu J, Li S, Lin W, Wang N, Bai L. Ferroptosis in Glaucoma: A Promising Avenue for Therapy. Adv Biol (Weinh) 2024; 8:e2300530. [PMID: 38411382 DOI: 10.1002/adbi.202300530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 01/08/2024] [Indexed: 02/28/2024]
Abstract
Glaucoma, a blind-leading disease largely since chronic pathological intraocular high pressure (ph-IOP). Hitherto, it is reckoned incurable for irreversible neural damage and challenges in managing IOP. Thus, it is significant to develop neuroprotective strategies. Ferroptosis, initially identified as an iron-dependent regulated death that triggers Fenton reactions and culminates in lipid peroxidation (LPO), has emerged as a focal point in multiple tumors and neurodegenerative diseases. Researches show that iron homeostasis play critical roles in the optic nerve (ON) and retinal ganglion cells (RGCs), suggesting targeted treatments could be effective. In glaucoma, apart from neural lesions, disrupted metal balance and increased oxidative stress in trabecular meshwork (TM) are observed. These disturbances lead to extracellular matrix excretion disorders, known as sclerotic mechanisms, resulting in refractory blockages. Importantly, oxidative stress, a significant downstream effect of ferroptosis, is also a key factor in cell senescence. It plays a crucial role in both the etiology and risk of glaucoma. Moreover, ferroptosis also induces non-infectious inflammation, which exacerbate glaucomatous injury. Therefore, the relevance of ferroptosis in glaucoma is extensive and multifaceted. In this review, the study delves into the current understanding of ferroptosis mechanisms in glaucoma, aiming to provide clues to inform clinical therapeutic practices.
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Affiliation(s)
- Jingyun Zhu
- Department of Ophthalmology, Nanfang Hospital, Southern Medical University, No.1023-1063, Shatai South Road, Baiyun District, Guangzhou, Guangdong, 510515, China
| | - Hui Chen
- Department of Geriatrics, Hospital of Traditional Chinese Medicine Affiliated to Southwest Medical University, No.182, Chunhui Road, Longmatan District, Luzhou, Sichuan, 646000, China
| | - Jian Wu
- Department of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, No. 8, East Chongwenmennei Street, Dongcheng District, Beijing, 100005, China
| | - Sen Li
- Department of Spinal Surgery, Drum Tower Hospital, Nanjing University, No. 321 Zhongshan Road, Gulou District, Nanjing, Jiangsu, 210008, China
| | - Wanying Lin
- Department of Ophthalmology, Nanfang Hospital, Southern Medical University, No.1023-1063, Shatai South Road, Baiyun District, Guangzhou, Guangdong, 510515, China
| | - Ningli Wang
- Department of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, No. 8, East Chongwenmennei Street, Dongcheng District, Beijing, 100005, China
| | - Lang Bai
- Department of Ophthalmology, Nanfang Hospital, Southern Medical University, No.1023-1063, Shatai South Road, Baiyun District, Guangzhou, Guangdong, 510515, China
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2
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Jing L, Liu K, Wang F, Su Y. Role of mechanically-sensitive cation channels Piezo1 and TRPV4 in trabecular meshwork cell mechanotransduction. Hum Cell 2024; 37:394-407. [PMID: 38316716 DOI: 10.1007/s13577-024-01035-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 01/17/2024] [Indexed: 02/07/2024]
Abstract
Glaucoma is one of the leading causes of irreversible blindness in developed countries, and intraocular pressure (IOP) is primary and only treatable risk factor, suggesting that to a significant extent, glaucoma is a disease of IOP disorder and pathological mechanotransduction. IOP-lowering ways are limited to decreaseing aqueous humour (AH) production or increasing the uveoscleral outflow pathway. Still, therapeutic approaches have been lacking to control IOP by enhancing the trabecular meshwork (TM) pathway. Trabecular meshwork cells (TMCs) have endothelial and myofibroblast properties and are responsible for the renewal of the extracellular matrix (ECM). Mechanosensitive cation channels, including Piezo1 and TRPV4, are abundantly expressed in primary TMCs and trigger mechanostress-dependent ECM and cytoskeletal remodelling. However, prolonged mechanical stimulation severely affects cellular biosynthesis through TMC mechanotransduction, including signaling, gene expression, ECM remodelling, and cytoskeletal structural changes, involving outflow facilities and elevating IOP. As for the functional coupling relationship between Piezo1 and TRPV4 channels, inspired by VECs and osteoblasts, we hypothesized that Piezo1 may also act upstream of TRPV4 in glaucomatous TM tissue, mediating the activation of TRPV4 via Ca2+ inflow or Ca2+ binding to phospholipase A2(PLA2), and thus be involved in increasing TM outflow resistance and elevated IOP. Therefore, this review aims to help identify new potential targets for IOP stabilization in ocular hypertension and primary open-angle glaucoma by understanding the mechanical transduction mechanisms associated with the development of glaucoma and may provide ideas into novel treatments for preventing the progression of glaucoma by targeting mechanotransduction.
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Affiliation(s)
- Lingling Jing
- Department of Ophthalmology, The Fourth Affiliated Hospital, Harbin Medical University, Harbin, China
| | - Kexin Liu
- Department of Ophthalmology, The Fourth Affiliated Hospital, Harbin Medical University, Harbin, China
| | - Feng Wang
- Department of Ophthalmology, The Fourth Affiliated Hospital, Harbin Medical University, Harbin, China.
| | - Ying Su
- Eye Hospital, The First Affiliated Hospital, Harbin Medical University, Harbin, China.
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3
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Youngblood H, Schoenlein PV, Pasquale LR, Stamer WD, Liu Y. Estrogen dysregulation, intraocular pressure, and glaucoma risk. Exp Eye Res 2023; 237:109725. [PMID: 37956940 PMCID: PMC10842791 DOI: 10.1016/j.exer.2023.109725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 10/20/2023] [Accepted: 11/08/2023] [Indexed: 11/19/2023]
Abstract
Characterized by optic nerve atrophy due to retinal ganglion cell (RGC) death, glaucoma is the leading cause of irreversible blindness worldwide. Of the major risk factors for glaucoma (age, ocular hypertension, and genetics), only elevated intraocular pressure (IOP) is modifiable, which is largely regulated by aqueous humor outflow through the trabecular meshwork. Glucocorticoids such as dexamethasone have long been known to elevate IOP and lead to glaucoma. However, several recent studies have reported that steroid hormone estrogen levels inversely correlate with glaucoma risk, and that variants in estrogen signaling genes have been associated with glaucoma. As a result, estrogen dysregulation may contribute to glaucoma pathogenesis, and estrogen signaling may protect against glaucoma. The mechanism for estrogen-related protection against glaucoma is not completely understood but likely involves both regulation of IOP homeostasis and neuroprotection of RGCs. Based upon its known activities, estrogen signaling may promote IOP homeostasis by affecting extracellular matrix turnover, focal adhesion assembly, actin stress fiber formation, mechanosensation, and nitric oxide production. In addition, estrogen receptors in the RGCs may mediate neuroprotective functions. As a result, the estrogen signaling pathway may offer a therapeutic target for both IOP control and neuroprotection. This review examines the evidence for a relationship between estrogen and IOP and explores the possible mechanisms by which estrogen maintains IOP homeostasis.
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Affiliation(s)
- Hannah Youngblood
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Patricia V Schoenlein
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA; Department of Radiology and Georgia Cancer Center, Augusta University, Augusta, GA, USA; Department of Surgery, Augusta University, Augusta, GA, USA
| | - Louis R Pasquale
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - W Daniel Stamer
- Department of Ophthalmology and Biomedical Engineering, Duke University, Durham, NC, USA
| | - Yutao Liu
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA; James and Jean Culver Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA, USA; Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA, USA.
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4
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Banasaz B, Zamzam R, Aghadoost D, Golabchi K, Morshedi M, Bayat M, Sadri Nahand J, Sheida A, Eshraghi R, Rahimzadeh Z, Mosavi SG, Goleij P, Rezaee A, Mirzaei H. Evaluation of expression pattern of cellular miRNAs (let-7b, miR-29a, miR-126, miR-34a, miR-181a-5p) and IL-6, TNF-α, and TGF-β in patients with pseudoexfoliation syndrome. Pathol Res Pract 2023; 249:154721. [PMID: 37591069 DOI: 10.1016/j.prp.2023.154721] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 07/20/2023] [Accepted: 07/26/2023] [Indexed: 08/19/2023]
Abstract
Pseudoexfoliation syndrome (PEX) is a critical clinical and biological extracellular matrix systemic disorder. Despite the unknown nature of PEX etiopathogenesis, it is proven to be associated with various genes and factors. The present research focused on analyzing the expression of miR and inflammatory cytokines in PEX. Serum and aqueous humor (AH) were collected prior to cataract surgery or trabeculectomy from 99 participants (64 with PEX glaucoma, and 35 controls). Real-time PCR was used for assessing the expression pattern of some miRNAs namely let-7b, miR-29a, miR-126, miR-34a, and miR-181a-5p. ELISA was carried out to explore the transcription of some inflammatory cytokines such as TGF-β, TNF-α, and IL-6. The indication of our results was a significant enhancement in the expression of let-7, miR-34a, and miR-181a-5p in PEX in contrast to the control group. Notwithstanding a significant suppression in miR-29a, and miR-126 expression levels in PEX in contrast to the control group. Analysis of ROC curve revealed that miR-29a and miR-34a are able to act as useful markers in order to discriminate the PEX group from the PEX negative subjects which were determined as the control group. According to the results obtained, the mean levels of TGF-β, TNF-α, and IL-6 upregulated among PEX subjects in contrast to control samples. In conclusion, our findings indicated that the selected cytokines alongside the selected miRNAs could be introduced as a biomarker panel in the diagnosis of PEX.
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Affiliation(s)
- Bahar Banasaz
- Internal Medicine Department, Babol University of Medical Sciences, Babol, Islamic Republic of Iran
| | - Razieh Zamzam
- School of Medicine, Kashan University of Medical Sciences, Kashan, Islamic Republic of Iran
| | - Davood Aghadoost
- Department of Ophthalmology, General Ophthalmologist, Matini Hospital, Kashan University of Medical Sciences, Kashan, Islamic Republic of Iran
| | - Khodayar Golabchi
- Department of Ophthalmology, General Ophthalmologist, Matini Hospital, Kashan University of Medical Sciences, Kashan, Islamic Republic of Iran
| | - Mohammadamin Morshedi
- School of Medicine, Kashan University of Medical Sciences, Kashan, Islamic Republic of Iran
| | - Mobina Bayat
- Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Islamic Republic of Iran
| | - Javid Sadri Nahand
- Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Islamic Republic of Iran
| | - Amirhossein Sheida
- School of Medicine, Kashan University of Medical Sciences, Kashan, Islamic Republic of Iran
| | - Reza Eshraghi
- School of Medicine, Kashan University of Medical Sciences, Kashan, Islamic Republic of Iran
| | - Zoha Rahimzadeh
- School of Medicine, Kashan University of Medical Sciences, Kashan, Islamic Republic of Iran
| | - Seyed Gholamabbas Mosavi
- Biostatistics Group, Health Faculty, Kashan University of Medical Sciences, Kashan, Islamic Republic of Iran
| | - Pouya Goleij
- Department of Genetics, Faculty of Biology, Sana Institute of Higher Education, Sari, Islamic Republic of Iran
| | - Aryan Rezaee
- Student Research Committee, School of Medicine, Iran University of Medical Sciences, Tehran, Islamic Republic of Iran.
| | - Hamed Mirzaei
- Research Center for Biochemistry and Nutrition in Metabolic Diseases, Institute for Basic Sciences, Kashan University, Kashan, Islamic Republic of Iran.
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Aboobakar IF, Collantes ERA, Hauser MA, Stamer WD, Wiggs JL. Rare protective variants and glaucoma-relevant cell stressors modulate Angiopoietin-like 7 expression. Hum Mol Genet 2023; 32:2523-2531. [PMID: 37220876 PMCID: PMC10360392 DOI: 10.1093/hmg/ddad083] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/10/2023] [Accepted: 05/11/2023] [Indexed: 05/25/2023] Open
Abstract
Rare missense and nonsense variants in the Angiopoietin-like 7 (ANGPTL7) gene confer protection from primary open-angle glaucoma (POAG), though the functional mechanism remains uncharacterized. Interestingly, a larger variant effect size strongly correlates with in silico predictions of increased protein instability (r = -0.98), suggesting that protective variants lower ANGPTL7 protein levels. Here, we show that missense and nonsense variants cause aggregation of mutant ANGPTL7 protein in the endoplasmic reticulum (ER) and decreased levels of secreted protein in human trabecular meshwork (TM) cells; a lower secreted:intracellular protein ratio strongly correlates with variant effects on intraocular pressure (r = 0.81). Importantly, accumulation of mutant protein in the ER does not increase expression of ER stress proteins in TM cells (P > 0.05 for all variants tested). Cyclic mechanical stress, a glaucoma-relevant physiologic stressor, also significantly lowers ANGPTL7 expression in primary cultures of human Schlemm's canal (SC) cells (-2.4-fold-change, P = 0.01). Collectively, these data suggest that the protective effects of ANGPTL7 variants in POAG stem from lower levels of secreted protein, which may modulate responses to physiologic and pathologic ocular cell stressors. Downregulation of ANGPTL7 expression may therefore serve as a viable preventative and therapeutic strategy for this common, blinding disease.
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Affiliation(s)
- Inas F Aboobakar
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA 02115, USA
| | - Edward Ryan A Collantes
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA 02115, USA
| | - Michael A Hauser
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC 27710, USA
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Biomedical Engineering, Duke University School of Medicine, Durham, NC 27710, USA
| | - Janey L Wiggs
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA 02115, USA
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Karimi A, Khan S, Razaghi R, Rahmati SM, Gathara M, Tudisco E, Aga M, Kelley MJ, Jian Y, Acott TS. Developing an experimental-computational workflow to study the biomechanics of the human conventional aqueous outflow pathway. Acta Biomater 2023; 164:346-362. [PMID: 37072067 PMCID: PMC10226761 DOI: 10.1016/j.actbio.2023.04.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 03/29/2023] [Accepted: 04/06/2023] [Indexed: 04/20/2023]
Abstract
The aqueous humor actively interacts with the trabecular meshwork (TM), juxtacanalicular tissue (JCT), and Schlemm's canal (SC) through a dynamic fluid-structure interaction (FSI) coupling. Despite the fact that intraocular pressure (IOP) undergoes significant fluctuations, our understanding of the hyperviscoelastic biomechanical properties of the aqueous outflow tissues is limited. In this study, a quadrant of the anterior segment from a normal human donor eye was dynamically pressurized in the SC lumen, and imaged using a customized optical coherence tomography (OCT). The TM/JCT/SC complex finite element (FE) with embedded collagen fibrils was reconstructed based on the segmented boundary nodes in the OCT images. The hyperviscoelastic mechanical properties of the outflow tissues' extracellular matrix with embedded viscoelastic collagen fibrils were calculated using an inverse FE-optimization method. Thereafter, the 3D microstructural FE model of the TM, with adjacent JCT and SC inner wall, from the same donor eye was constructed using optical coherence microscopy and subjected to a flow load-boundary from the SC lumen. The resultant deformation/strain in the outflow tissues was calculated using the FSI method, and compared to the digital volume correlation (DVC) data. TM showed larger shear modulus (0.92 MPa) compared to the JCT (0.47 MPa) and SC inner wall (0.85 MPa). Shear modulus (viscoelastic) was larger in the SC inner wall (97.65 MPa) compared to the TM (84.38 MPa) and JCT (56.30 MPa). The conventional aqueous outflow pathway is subjected to a rate-dependent IOP load-boundary with large fluctuations. This necessitates addressing the biomechanics of the outflow tissues using hyperviscoelastic material-model. STATEMENT OF SIGNIFICANCE: While the human conventional aqueous outflow pathway is subjected to a large-deformation and time-dependent IOP load-boundary, we are not aware of any studies that have calculated the hyperviscoelastic mechanical properties of the outflow tissues with embedded viscoelastic collagen fibrils. A quadrant of the anterior segment of a normal humor donor eye was dynamically pressurized from the SC lumen with relatively large fluctuations. The TM/JCT/SC complex were OCT imaged and the mechanical properties of the tissues with embedded collagen fibrils were calculated using the inverse FE-optimization algorithm. The resultant displacement/strain in the FSI outflow model was validated versus the DVC data. The proposed experimental-computational workflow may significantly contribute to understanding of the effects of different drugs on the biomechanics of the conventional aqueous outflow pathway.
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Affiliation(s)
- Alireza Karimi
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Shanjida Khan
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR, USA
| | - Reza Razaghi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, USA
| | | | - Michael Gathara
- Department of Computer Science, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Erika Tudisco
- Division of Geotechnical Engineering, Lund University, Lund, Sweden
| | - Mini Aga
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Mary J Kelley
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA; Department Integrative Biosciences, School of Dentistry, Oregon Health & Science University, Portland, OR, USA
| | - Yifan Jian
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA; Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR, USA
| | - Ted S Acott
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA; Department Chemical Physiology & Biochemistry, School of Medicine, Oregon Health & Science University, Portland, OR, USA.
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Xiao R, Lei C, Zhang Y, Zhang M. Interleukin-6 in retinal diseases: From pathogenesis to therapy. Exp Eye Res 2023:109556. [PMID: 37385535 DOI: 10.1016/j.exer.2023.109556] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Revised: 06/03/2023] [Accepted: 06/25/2023] [Indexed: 07/01/2023]
Abstract
Interleukin-6 (IL-6) is a pleiotropic cytokine that participates in immunomodulation, inflammation, increases vascular permeability, hematopoiesis, and stimulates cell proliferation, among other biological processes. It exerts effects primarily through the classic and trans-signaling pathways. Many studies have demonstrated that IL-6 plays a critical role in the development of retinal diseases including diabetic retinopathy, uveitis, age-related macular degeneration, glaucoma, retinal vein occlusion, central serous chorioretinopathy and proliferative vitreoretinopathy. Thus, the progressive development of drugs targeting IL-6 and IL-6 receptor may play a role in the treatment of multiple retinal diseases. In this article, we comprehensively review the IL-6's biological functions of and its mechanisms in the pathogenesis of various retinal diseases. Furthermore, we summarize the drugs targeting IL-6 and its receptor and prospect their potential application in retinal diseases, hoping to provide new ideas for the treatment of retinal diseases.
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Affiliation(s)
- Ruihan Xiao
- Department of Ophthalmology and Research Laboratory of Macular Disease, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Chunyan Lei
- Department of Ophthalmology and Research Laboratory of Macular Disease, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Yi Zhang
- Department of Ophthalmology and Research Laboratory of Macular Disease, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Meixia Zhang
- Department of Ophthalmology and Research Laboratory of Macular Disease, West China Hospital, Sichuan University, Chengdu, 610041, China.
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Sacco R, Chiaravalli G, Antman G, Guidoboni G, Verticchio A, Siesky B, Harris A. The role of conventional and unconventional adaptive routes in lowering of intraocular pressure: Theoretical model and simulation. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2023; 35:061902. [PMID: 37305147 PMCID: PMC10251427 DOI: 10.1063/5.0151091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Accepted: 05/19/2023] [Indexed: 06/13/2023]
Abstract
In this article, we propose a theoretical model leveraging the analogy between fluid and electric variables to investigate the relation among aqueous humor (AH) circulation and drainage and intraocular pressure (IOP), the principal established risk factor of severe neuropathologies of the optic nerve such as glaucoma. IOP is the steady-state result of the balance among AH secretion (AHs), circulation (AHc), and drainage (AHd). AHs are modeled as a given volumetric flow rate electrically corresponding to an input current source. AHc is modeled by the series of two linear hydraulic conductances (HCs) representing the posterior and anterior chambers. AHd is modeled by the parallel of three HCs: a linear HC for the conventional adaptive route (ConvAR), a nonlinear HC for the hydraulic component of the unconventional adaptive route (UncAR), and a nonlinear HC for the drug-dependent component of the UncAR. The proposed model is implemented in a computational virtual laboratory to study the value attained by the IOP under physiological and pathological conditions. Simulation results (i) confirm the conjecture that the UncAR acts as a relief valve under pathological conditions, (ii) indicate that the drug-dependent AR is the major opponent to IOP increase in the case of elevated trabecular meshwork resistance, and (iii) support the use of the model as a quantitative tool to complement in vivo studies and help design and optimize medications for ocular diseases.
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Affiliation(s)
- Riccardo Sacco
- Dipartimento di Matematica, Politecnico di Milano, 20133 Milano, Italy
| | | | | | | | - Alice Verticchio
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Brent Siesky
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Alon Harris
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
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Karimi A, Crouch DJ, Razaghi R, Crawford Downs J, Acott TS, Kelley MJ, Behnsen JG, Bosworth LA, Sheridan CM. Morphological and biomechanical analyses of the human healthy and glaucomatous aqueous outflow pathway: Imaging-to-modeling. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 236:107485. [PMID: 37149973 DOI: 10.1016/j.cmpb.2023.107485] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/09/2023] [Accepted: 03/13/2023] [Indexed: 05/09/2023]
Abstract
BACKGROUND AND OBJECTIVE Intraocular pressure (IOP) is maintained via a dynamic balance between the production of aqueous humor and its drainage through the trabecular meshwork (TM), juxtacanalicular connective tissue (JCT), and Schlemm's canal (SC) endothelium of the conventional outflow pathway. Primary open angle glaucoma (POAG) is often associated with IOP elevation that occurs due to an abnormally high outflow resistance across the outflow pathway. Outflow tissues are viscoelastic and actively interact with aqueous humor dynamics through a two-way fluid-structure interaction coupling. While glaucoma affects the morphology and stiffness of the outflow tissues, their biomechanics and hydrodynamics in glaucoma eyes remain largely unknown. This research aims to develop an image-to-model method allowing the biomechanics and hydrodynamics of the conventional aqueous outflow pathway to be studied. METHODS We used a combination of X-ray computed tomography and scanning electron microscopy to reconstruct high-fidelity, eye-specific, 3D microstructural finite element models of the healthy and glaucoma outflow tissues in cellularized and decellularized conditions. The viscoelastic TM/JCT/SC complex finite element models with embedded viscoelastic beam elements were subjected to a physiological IOP load boundary; the stresses/strains and the flow state were calculated using fluid-structure interaction and computational fluid dynamics. RESULTS Based on the resultant hydrodynamics parameters across the outflow pathway, the primary site of outflow resistance in healthy eyes was in the JCT and immediate vicinity of the SC inner wall, while the majority of the outflow resistance in the glaucoma eyes occurred in the TM. The TM and JCT in the glaucoma eyes showed 1.32-fold and 1.13-fold larger beam thickness and smaller trabecular space size (2.24-fold and 1.50-fold) compared to the healthy eyes. CONCLUSIONS Characterizing the accurate morphology of the outflow tissues may significantly contribute to constructing more accurate, robust, and reliable models, that can eventually help to better understand the dynamic IOP regulation, hydrodynamics of the aqueous humor, and outflow resistance dynamic in the human eyes. This model demonstrates proof of concept for determining changes to outflow resistance in healthy and glaucomatous tissues and thus may be utilized in larger cohorts of donor tissues where disease specificity, race, age, and gender of the eye donors may be accounted for.
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Affiliation(s)
- Alireza Karimi
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Devon J Crouch
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L7 8TX, United Kingdom
| | - Reza Razaghi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, United States
| | - J Crawford Downs
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Ted S Acott
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States; Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon, United States
| | - Mary J Kelley
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States; Department of Integrative Biosciences, Oregon Health & Science University, Portland, Oregon, United States
| | - Julia G Behnsen
- Department of Mechanical, Materials, and Aerospace Engineering, University of Liverpool, Liverpool, L69 6GB, United Kingdom
| | - Lucy A Bosworth
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L7 8TX, United Kingdom
| | - Carl M Sheridan
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L7 8TX, United Kingdom.
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10
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Liton PB, Boesze-Battaglia K, Boulton ME, Boya P, Ferguson TA, Ganley IG, Kauppinnen A, Laurie GW, Mizushima N, Morishita H, Russo R, Sadda J, Shyam R, Sinha D, Thompson DA, Zacks DN. AUTOPHAGY IN THE EYE: FROM PHYSIOLOGY TO PATHOPHYSOLOGY. AUTOPHAGY REPORTS 2023; 2:2178996. [PMID: 37034386 PMCID: PMC10078619 DOI: 10.1080/27694127.2023.2178996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 01/26/2023] [Indexed: 03/05/2023]
Abstract
Autophagy is a catabolic self-degradative pathway that promotes the degradation and recycling of intracellular material through the lysosomal compartment. Although first believed to function in conditions of nutritional stress, autophagy is emerging as a critical cellular pathway, involved in a variety of physiological and pathophysiological processes. Autophagy dysregulation is associated with an increasing number of diseases, including ocular diseases. On one hand, mutations in autophagy-related genes have been linked to cataracts, glaucoma, and corneal dystrophy; on the other hand, alterations in autophagy and lysosomal pathways are a common finding in essentially all diseases of the eye. Moreover, LC3-associated phagocytosis, a form of non-canonical autophagy, is critical in promoting visual cycle function. This review collects the latest understanding of autophagy in the context of the eye. We will review and discuss the respective roles of autophagy in the physiology and/or pathophysiology of each of the ocular tissues, its diurnal/circadian variation, as well as its involvement in diseases of the eye.
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Affiliation(s)
- Paloma B. Liton
- Departments of Ophthalmology & Pathology, Duke School of Medicine, Duke University, Durham, NC 27705, USA
| | - Kathleen Boesze-Battaglia
- Department of Basic and Translational Sciences, University of Pennsylvania, School of Dental Medicine, Philadelphia, PA 19104, USA
| | - Michael E. Boulton
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham (UAB), Birmingham, AL, USA
| | - Patricia Boya
- Department of Neuroscience and Movement Science. Faculty of Science and Medicine, University of Fribourg, 1700 Fribourg, Switzerland
| | - Thomas A. Ferguson
- Department of Ophthalmology and Visual Sciences, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Ian G. Ganley
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Anu Kauppinnen
- Faculty of Health and Sciences, School of Pharmacy, University of Eastern Finland, 70210 Kuopio, Finland
| | - Gordon W. Laurie
- Departments of Cell Biology, Ophthalmology and Biomedical Engineering, University of Virginia, Charlottesville, VA 22908, USA
| | - Noboru Mizushima
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, 113-0033, Japan
| | - Hideaki Morishita
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, 113-0033, Japan
- Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Rossella Russo
- Preclinical and Translational Pharmacology, Glaucoma Unit, Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, 87036 Rende, Italy
| | - Jaya Sadda
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan Medical School, Ann Arbor, MI, USA
| | | | - Debasish Sinha
- Department of Ophthalmology, Cell Biology, and Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Debra A. Thompson
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan Medical School, Ann Arbor, MI, USA
| | - David N. Zacks
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan Medical School, Ann Arbor, MI, USA
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11
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Abstract
The trabecular meshwork (TM) of the eye serves as an essential tissue in controlling aqueous humor (AH) outflow and intraocular pressure (IOP) homeostasis. However, dysfunctional TM cells and/or decreased TM cellularity is become a critical pathogenic cause for primary open-angle glaucoma (POAG). Consequently, it is particularly valuable to investigate TM characteristics, which, in turn, facilitates the development of new treatments for POAG. Since 2006, the advancement in induced pluripotent stem cells (iPSCs) provides a new tool to (1) model the TM in vitro and (2) regenerate degenerative TM in POAG. In this context, we first summarize the current approaches to induce the differentiation of TM-like cells from iPSCs and compare iPSC-derived TM models to the conventional in vitro TM models. The efficacy of iPSC-derived TM cells for TM regeneration in POAG models is also discussed. Through these approaches, iPSCs are becoming essential tools in glaucoma modeling and for developing personalized treatments for TM regeneration.
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Affiliation(s)
- Wei Zhu
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao, China.
- Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beihang University & Capital Medical University, Beijing, China.
| | - Xiaoyan Zhang
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao, China
| | - Shen Wu
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Capital Medical University, Beijing, China
| | - Ningli Wang
- Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beihang University & Capital Medical University, Beijing, China
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Capital Medical University, Beijing, China
| | - Markus H Kuehn
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA, USA
- Center for the Prevention and Treatment of Visual Loss, Iowa City Veterans Affairs Medical Center, Iowa City, IA, USA
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12
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Mastronikolis S, Kagkelaris K, Pagkalou M, Tsiambas E, Plotas P, Georgakopoulos CD. Antioxidant Defense and Pseudoexfoliation Syndrome: An Updated Review. MEDICAL SCIENCES (BASEL, SWITZERLAND) 2022; 10:medsci10040068. [PMID: 36548003 PMCID: PMC9785126 DOI: 10.3390/medsci10040068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/04/2022] [Accepted: 12/13/2022] [Indexed: 12/15/2022]
Abstract
Oxidative stress (OS) affects the anterior ocular tissues, rendering them susceptible to several eye diseases. On the other hand, protection of the eye from harmful factors is achieved by unique defense mechanisms, including enzymatic and non-enzymatic antioxidants. The imbalance between oxidants and antioxidants could be the cause of pseudoexfoliation syndrome (PEXS), a condition of defective extracellular matrix (ECM) remodeling. A systematic English-language literature review was conducted from May 2022 to June 2022. The main antioxidant enzymes protecting the eye from reactive oxygen species (ROS) are superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), which catalyze the reduction of specific types of ROS. Similarly, non-enzymatic antioxidants such as vitamins A, E and C, carotenoids and glutathione (GSH) are involved in removing ROS from the cells. PEXS is a genetic disease, however, environmental and dietary factors also influence its development. Additionally, many OS products disrupting the ECM remodeling process and modifying the antioxidative defense status could lead to PEXS. This review discusses the antioxidative defense of the eye in association with PEXS, and the intricate link between OS and PEXS. Understanding the pathways of PEXS evolution, and developing new methods to reduce OS, are crucial to control and treat this disease. However, further studies are required to elucidate the molecular pathogenesis of PEXS.
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Affiliation(s)
- Stylianos Mastronikolis
- Department of Ophthalmology, Medical School, University of Patras, 26504 Patras, Greece
- Department of Neurosurgery, James Cook University Hospital, Middlesbrough TS4 3BW, UK
- Correspondence: (S.M.); (P.P.)
| | | | - Marina Pagkalou
- Department of Chemistry, University of Crete, 71500 Heraklion, Greece
| | | | - Panagiotis Plotas
- Laboratory of Primary Health Care, School of Health Rehabilitation Sciences, University of Patras, 26504 Patras, Greece
- Correspondence: (S.M.); (P.P.)
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13
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Karimi A, Razaghi R, Padilla S, Rahmati SM, Downs JC, Acott TS, Kelley MJ, Wang RK, Johnstone M. Viscoelastic Biomechanical Properties of the Conventional Aqueous Outflow Pathway Tissues in Healthy and Glaucoma Human Eyes. J Clin Med 2022; 11:6049. [PMID: 36294371 PMCID: PMC9605362 DOI: 10.3390/jcm11206049] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 10/11/2022] [Accepted: 10/12/2022] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Although the tissues comprising the ocular conventional outflow pathway have shown strong viscoelastic mechanical response to aqueous humor pressure dynamics, the viscoelastic mechanical properties of the trabecular meshwork (TM), juxtacanalicular connective tissue (JCT), and Schlemm's canal (SC) inner wall are largely unknown. METHODS A quadrant of the anterior segment from two human donor eyes at low- and high-flow (LF and HF) outflow regions was pressurized and imaged using optical coherence tomography (OCT). A finite element (FE) model of the TM, the adjacent JCT, and the SC inner wall was constructed and viscoelastic beam elements were distributed in the extracellular matrix (ECM) of the TM and JCT to represent anisotropic collagen. An inverse FE-optimization algorithm was used to calculate the viscoelastic properties of the ECM/beam elements such that the TM/JCT/SC model and OCT imaging data best matched over time. RESULTS The ECM of the glaucoma tissues showed significantly larger time-dependent shear moduli compared to the heathy tissues. Significantly larger shear moduli were also observed in the LF regions of both the healthy and glaucoma eyes compared to the HF regions. CONCLUSIONS The outflow tissues in both glaucoma eyes and HF regions are stiffer and less able to respond to dynamic IOP.
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Affiliation(s)
- Alireza Karimi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Reza Razaghi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Steven Padilla
- Department of Ophthalmology, University of Washington, Seattle, WA 98109, USA
| | | | - J. Crawford Downs
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Ted S. Acott
- Departments of Ophthalmology and Biochemistry and Molecular Biology, Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Mary J. Kelley
- Departments of Ophthalmology and Integrative Biosciences, Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Ruikang K. Wang
- Department of Ophthalmology, University of Washington, Seattle, WA 98109, USA
- Department of Bioengineering, University of Washington, Seattle, WA 98105, USA
| | - Murray Johnstone
- Department of Ophthalmology, University of Washington, Seattle, WA 98109, USA
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14
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Shim MS, Liton PB. The physiological and pathophysiological roles of the autophagy lysosomal system in the conventional aqueous humor outflow pathway: More than cellular clean up. Prog Retin Eye Res 2022; 90:101064. [PMID: 35370083 PMCID: PMC9464695 DOI: 10.1016/j.preteyeres.2022.101064] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 03/09/2022] [Accepted: 03/25/2022] [Indexed: 10/18/2022]
Abstract
During the last few years, the autophagy lysosomal system is emerging as a central cellular pathway with roles in survival, acting as a housekeeper and stress response mechanism. Studies by our and other labs suggest that autophagy might play an essential role in maintaining aqueous humor outflow homeostasis, and that malfunction of autophagy in outflow pathway cells might predispose to ocular hypertension and glaucoma pathogenesis. In this review, we will collect the current knowledge and discuss the molecular mechanisms by which autophagy does or might regulate normal outflow pathway tissue function, and its response to different types of stressors (oxidative stress and mechanical stress). We will also discuss novel roles of autophagy and lysosomal enzymes in modulation of TGFβ signaling and ECM remodeling, and the link between dysregulated autophagy and cellular senescence. We will examine what we have learnt, using pre-clinical animal models about how dysregulated autophagy can contribute to disease and apply that to the current status of autophagy in human glaucoma. Finally, we will consider and discuss the challenges and the potential of autophagy as a therapeutic target for the treatment of ocular hypertension and glaucoma.
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Affiliation(s)
- Myoung Sup Shim
- Duke University, Department of Ophthalmology, Durham, NC, 27705, USA
| | - Paloma B Liton
- Duke University, Department of Ophthalmology, Durham, NC, 27705, USA.
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15
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Chen Y, Su Y, Wang F. The Piezo1 ion channel in glaucoma: a new perspective on mechanical stress. Hum Cell 2022; 35:1307-1322. [PMID: 35767143 DOI: 10.1007/s13577-022-00738-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 06/13/2022] [Indexed: 11/26/2022]
Abstract
Glaucomatous optic nerve damage caused by pathological intraocular pressure elevation is irreversible, and its course is often difficult to control. This group of eye diseases is closely related to biomechanics, and the correlation between glaucoma pathogenesis and mechanical stimulation has been studied in recent decades. The nonselective cation channel Piezo1, the most important known mechanical stress sensor, is a transmembrane protein widely expressed in various cell types. Piezo1 has been detected throughout the eye, and the close relationship between Piezo1 and glaucoma is being confirmed. Pathological changes in glaucoma occur in both the anterior and posterior segments of the eye, and it is of great interest for researchers to determine whether Piezo1 plays a role in these changes and how it functions. The elucidation of the mechanisms of Piezo1 action in nonocular tissues and the reported roles of similar mechanically activated ion channels in glaucoma will provide an appropriate basis for further investigation. From a new perspective, this review provides a detailed description of the current progress in elucidating the role of Piezo1 in glaucoma, including relevant questions and assumptions, the remaining challenging research directions and mechanism-related therapeutic potential.
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Affiliation(s)
- Yidan Chen
- Department of Ophthalmology, Fourth Affiliated Hospital, Harbin Medical University, Yiyuan Road, Harbin, 150001, China
| | - Ying Su
- Eye Hospital, First Affiliated Hospital, Harbin Medical University, Yiman Road, Harbin, 150007, China.
| | - Feng Wang
- Department of Ophthalmology, Fourth Affiliated Hospital, Harbin Medical University, Yiyuan Road, Harbin, 150001, China.
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16
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Identification of Estrogen Signaling in a Prioritization Study of Intraocular Pressure-Associated Genes. Int J Mol Sci 2021; 22:ijms221910288. [PMID: 34638643 PMCID: PMC8508848 DOI: 10.3390/ijms221910288] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 09/20/2021] [Accepted: 09/22/2021] [Indexed: 12/12/2022] Open
Abstract
Elevated intraocular pressure (IOP) is the only modifiable risk factor for primary open-angle glaucoma (POAG). Herein we sought to prioritize a set of previously identified IOP-associated genes using novel and previously published datasets. We identified several genes for future study, including several involved in cytoskeletal/extracellular matrix reorganization, cell adhesion, angiogenesis, and TGF-β signaling. Our differential correlation analysis of IOP-associated genes identified 295 pairs of 201 genes with differential correlation. Pathway analysis identified β-estradiol as the top upstream regulator of these genes with ESR1 mediating 25 interactions. Several genes (i.e., EFEMP1, FOXC1, and SPTBN1) regulated by β-estradiol/ESR1 were highly expressed in non-glaucomatous human trabecular meshwork (TM) or Schlemm’s canal (SC) cells and specifically expressed in TM/SC cell clusters defined by single-cell RNA-sequencing. We confirmed ESR1 gene and protein expression in human TM cells and TM/SC tissue with quantitative real-time PCR and immunofluorescence, respectively. 17β-estradiol was identified in bovine, porcine, and human aqueous humor (AH) using ELISA. In conclusion, we have identified estrogen receptor signaling as a key modulator of several IOP-associated genes. The expression of ESR1 and these IOP-associated genes in TM/SC tissue and the presence of 17β-estradiol in AH supports a role for estrogen signaling in IOP regulation.
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17
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Luna C, Parker M, Challa P, Gonzalez P. Long-Term Decrease of Intraocular Pressure in Rats by Viral Delivery of miR-146a. Transl Vis Sci Technol 2021; 10:14. [PMID: 34254987 PMCID: PMC8287046 DOI: 10.1167/tvst.10.8.14] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Purpose To evaluate the effects of miR-146a in trabecular meshwork (TM) cells and on intraocular pressure (IOP) in vivo via viral delivery of miR-146a to the anterior chamber of rat eyes. Methods Human TM cells were transfected with miR-146 mimic or inhibitor. Some cells from each group were then subjected to cyclic mechanical stress (CMS). Other cells from each group had no force applied. Gene expression was then analyzed by quantitative polymerase chain reaction (qPCR). Replication-deficient adenovirus and lentivirus expressing miR-146a were inoculated into the anterior segment of Brown Norway rat eyes. IOP was monitored by rebound tonometry, visual acuity was evaluated by optokinetic tracking (OKT), and inflammation markers in the anterior segment were examined by slit-lamp, qPCR, and semi-thin sections. Results miR-146 affected the expression of genes potentially involved in outflow homeostasis at basal levels and under CMS. Both lentiviral and adenoviral vectors expressing miR-146a resulted in sustained decreases in IOP ranging from 2.6 to 4.4 mmHg. Long term follow-up of rats injected with lentiviral vectors showed a sustained effect on IOP of 4.4 ± 2.9 mmHg that lasted until rats were sacrificed more than 8 months later. Eyes showed no signs of inflammation, loss of visual acuity, or other visible abnormalities. Conclusions Intracameral delivery of miR-146a can provide a long-term decrease of IOP in rats without signs of inflammation or other visible adverse effects. Transitional Relevance The IOP-lowering effects of miR-146 observed in rats provides a necessary step toward the development of an effective gene therapy for glaucoma in humans.
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18
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Sundaresan Y, Ramasamy KS, Veerappan M, Chidambaranathan GP. Functional characterization of adult human trabecular meshwork stem cells. Exp Cell Res 2021; 405:112709. [PMID: 34174318 DOI: 10.1016/j.yexcr.2021.112709] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 05/13/2021] [Accepted: 06/21/2021] [Indexed: 10/21/2022]
Abstract
We earlier identified native human trabecular meshwork stem cells (TMSCs) based on two-parameters- high ABCG2 expression and high nucleus to cytoplasmic ratio. The TMSCs also expressed p75 and AnkyrinG. Based on the high expression of ABCG2 and p75, the TMSCs were identified to be located in the Schwalbe's line region of the TM. In continuation, the current study aimed at elucidating the functional characteristics of human TMSCs. Upon culturing, only a small proportion of TM cells (0.96 ± 0.21% in <30 years) expressing stem cell markers ABCG2 and p75 adhered to the culture dish. This proportion significantly reduced with ageing (0.32 ± 0.23% in 30-60 years and 0.35 ± 0.04% in >60 years). Characterization of the primary TM cultures identified 7.00 ± 1.80% of stem cells with label retaining property. Further, cultured cells had the ability to form TM spheres (0.82 ± 0.23%) which consisted of high ABCG2 and p75 positive cells. Upon dexamethasone induction, 86.00 ± 14.87% and 64.60 ± 7.24% of the cells derived from the TM spheres expressed myocilin and exhibited cross linked actin networks respectively, indicating differentiation of the TMSCs in the sphere to TM cells. In addition, the sphere derived TM cells also possessed phagocytic potential (13.28 ± 3.30%) equivalent to primary TM cells (16.33 ± 4.04%) which was evident upon internalization of zymosan particles. In conclusion, this study has established that a proportion of cultured TM cells had the label retaining property as well as sphere forming ability of adult stem cells. Thus, these results confirm the presence of adult stem cells in the human TM that might be responsible for the maintenance of tissue homeostasis.
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Affiliation(s)
- Yogapriya Sundaresan
- Department of Immunology and Stem Cell Biology, Aravind Medical Research Foundation, Madurai, Tamil Nadu, India
| | - Krishnadas Subbiah Ramasamy
- Glaucoma Clinic, Aravind Eye Hospital and Post Graduate Institute of Ophthalmology, Madurai, Tamil Nadu, India
| | - Muthukkaruppan Veerappan
- Department of Immunology and Stem Cell Biology, Aravind Medical Research Foundation, Madurai, Tamil Nadu, India
| | - Gowri Priya Chidambaranathan
- Department of Immunology and Stem Cell Biology, Aravind Medical Research Foundation, Madurai, Tamil Nadu, India.
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19
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Lim SY, Betzler BK, Yip LWL, Dorairaj S, Ang BCH. Standalone XEN45 Gel Stent implantation versus combined XEN45-phacoemulsification in the treatment of open angle glaucoma-a systematic review and meta-analysis. Graefes Arch Clin Exp Ophthalmol 2021; 259:3209-3219. [PMID: 33914156 DOI: 10.1007/s00417-021-05189-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 03/19/2021] [Accepted: 04/07/2021] [Indexed: 11/28/2022] Open
Abstract
PURPOSE The XEN45 Gel Stent is currently the only FDA-approved sub-conjunctival minimally invasive glaucoma surgery (MIGS) procedure. It has been used worldwide either as a standalone implantation procedure or in combination with phacoemulsification surgery. Concomitant phacoemulsification is understood to influence outcomes of traditional subconjunctival filtering surgery. However, the comparative efficacy between standalone XEN45 Gel Sent implantation ("Standalone XEN45") and combined XEN-phacoemulsification surgery ("XEN45-Phaco") remains unclear. This study aims to appraise current literature to compare the efficacy of Standalone XEN45 and XEN45-Phaco in open-angle glaucoma. METHODS A comprehensive search of PubMed, CINAHL, CENTRAL databases was performed with the terms "Xen surgery" followed by selective vetting. Pilot, cohort, observational studies and randomised controlled trials that included at least 10 patients undergoing either Standalone XEN45 or XEN45-Phaco surgeries for the treatment of open-angle glaucoma were deemed eligible for inclusion after independent assessment by 2 authors. The search workflow was reported according to the PRISMA guidelines. Data was pooled using random-effects model. A meta-analysis of continuous outcome and proportions was performed using the meta routine in R v3.2.1. RESULTS Ten studies were included. There was a statistically significant difference in IOP reduction favouring Standalone XEN45 at post-operative day 1, week 1, months 1, 3 and 6. There was a statistically significant difference in decrease in IOP-lowering medications favouring Standalone XEN45 at post-operative week 1 and month 1. CONCLUSION Standalone XEN45 has superior IOP-lowering outcomes compared to XEN45-Phaco in the early post-operative period, up to 6 months after surgery.
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Affiliation(s)
- Sheng Yang Lim
- Department of Ophthalmology, National University Hospital, National University Hospital Systems, 5 Lower Kent Ridge Road, Singapore, 119074, Singapore.
| | - Bjorn Kaijun Betzler
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Leonard Wei Leon Yip
- Department of Ophthalmology, Tan Tock Seng Hospital, National Healthcare Group Eye Institute, 11 Jln Tan Tock Seng, Singapore, 308433, Singapore
| | - Syril Dorairaj
- Department of Ophthalmology, Mayo Clinic, Rochester, USA
| | - Bryan Chin Hou Ang
- Department of Ophthalmology, Tan Tock Seng Hospital, National Healthcare Group Eye Institute, 11 Jln Tan Tock Seng, Singapore, 308433, Singapore.
- Department of Ophthalmology, Woodlands Health Campus, Singapore, Singapore.
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20
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Salimi A, Abu-Nada M, Harasymowycz P. Matched Cohort Study of Cataract Surgery With and Without Trabecular Microbypass Stent Implantation in Primary Angle-Closure Glaucoma. Am J Ophthalmol 2021; 224:310-320. [PMID: 33428885 DOI: 10.1016/j.ajo.2020.12.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/28/2020] [Accepted: 12/28/2020] [Indexed: 02/06/2023]
Abstract
PURPOSE To compare 1-year outcomes of phacoemulsification alone (phaco-only) vs phacoemulsification with implantation of 2 trabecular microbypass stents (iStent or iStent inject; phaco-stent) in eyes with primary angle-closure glaucoma (PACG). DESIGN Retrospective matched clinical cohort study. METHODS PACG eyes that underwent phaco-only vs phaco-stent at a single ophthalmology center. Groups were matched for baseline intraocular pressure (IOP) and medication use with a tolerance of ±2 mm Hg and ±1 medication, respectively. Primary outcomes included postoperative change in the mean IOP and medications. One-year outcomes were assessed using generalized estimating equations corrected for baseline intergroup differences. RESULTS One hundred fifty-eight eyes (79 per group) were included. At 1 year, IOP decreased by 13% (from 16.8 ± 3.1 mm Hg preoperatively) in the phaco-only group (P < .001) and by 27% (from 17.6 ± 3.2 mm Hg) in the phaco-stent group (P < .001). Medication use decreased by 11% (from 1.8 ± 1.3 medications preoperatively) in the phaco-only group (P < .001) and by 46% (from 2.2 ± 1.2 medications) in the phaco-stent group (P < .001). The phaco-stent group experienced significantly larger reductions in IOP and medications compared with the phaco-only group (P < .001). The incidence of IOP spikes was significantly greater in the phaco-only group (18%) compared with the phaco-stent group (4%; P = .005). Safety was favorable with few transient postoperative adverse events. CONCLUSION The results of this study highlight that phacoemulsification with implantation of 2 trabecular microbypass stents is more effective and possibly more protective than phaco-only in PACG eyes, as evidenced by significantly larger IOP and medication reductions and smaller incidences of IOP spikes among the phaco-stent eyes.
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21
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Zhu W, Hou F, Fang J, Bahrani Fard MR, Liu Y, Ren S, Wu S, Qi Y, Sui S, Read AT, Sherwood JM, Zou W, Yu H, Zhang J, Overby DR, Wang N, Ethier CR, Wang K. The role of Piezo1 in conventional aqueous humor outflow dynamics. iScience 2021; 24:102042. [PMID: 33532718 PMCID: PMC7829208 DOI: 10.1016/j.isci.2021.102042] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 12/16/2020] [Accepted: 01/05/2021] [Indexed: 12/16/2022] Open
Abstract
Controlling intraocular pressure (IOP) remains the mainstay of glaucoma therapy. The trabecular meshwork (TM), the key tissue responsible for aqueous humor (AH) outflow and IOP maintenance, is very sensitive to mechanical forces. However, it is not understood whether Piezo channels, very sensitive mechanosensors, functionally influence AH outflow. Here, we characterize the role of Piezo1 in conventional AH outflow. Immunostaining and western blot analysis showed that Piezo1 is widely expressed by TM. Patch-clamp recordings in TM cells confirmed the activation of Piezo1-derived mechanosensitive currents. Importantly, the antagonist GsMTx4 for mechanosensitive channels significantly decreased steady-state facility, yet activation of Piezo1 by the specific agonist Yoda1 did not lead to a facility change. Furthermore, GsMTx4, but not Yoda1, caused a significant increase in ocular compliance, a measure of the eye's transient response to IOP perturbation. Our findings demonstrate a potential role for Piezo1 in conventional outflow, likely under pathological and rapid transient conditions. Piezo1 is functionally expressed in the TM, the most important tissue controlling IOP Suppression of mechanosensitive channel leads to a significant decrease in facility Our data suggest a role for Piezo in pathological situations and rapid IOP transients
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Affiliation(s)
- Wei Zhu
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China.,Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beihang University & Capital Medical University, Beijing 100730, China
| | - Fei Hou
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China.,Department of Pharmacy, Affiliated Hospital of Qingdao University, Qingdao 266003, China
| | - Jingwang Fang
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China
| | - Mohammad Reza Bahrani Fard
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta 30332, GA, USA
| | - Yani Liu
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China
| | - Shouyan Ren
- Department of Pharmacy, Affiliated Hospital of Qingdao University, Qingdao 266003, China
| | - Shen Wu
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Beijing 100730 China
| | - Yunkun Qi
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China
| | - Shangru Sui
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China
| | - A Thomas Read
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta 30332, GA, USA
| | | | - Wei Zou
- School of Mechatronic Engineering, Jiangsu Normal University, Xuzhou 221116, China
| | - Hongxia Yu
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China
| | - Jingxue Zhang
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Beijing 100730 China
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, UK
| | - Ningli Wang
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Beijing 100730 China
| | - C Ross Ethier
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta 30332, GA, USA.,Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, 30332, GA, United States
| | - KeWei Wang
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China.,Institute of Innovative Drugs, Qingdao University, 38 Dengzhou Road, Qingdao 266021, Shandong, China
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Cathepsin B Localizes in the Caveolae and Participates in the Proteolytic Cascade in Trabecular Meshwork Cells. Potential New Drug Target for the Treatment of Glaucoma. J Clin Med 2020; 10:jcm10010078. [PMID: 33379277 PMCID: PMC7795952 DOI: 10.3390/jcm10010078] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/17/2020] [Accepted: 12/24/2020] [Indexed: 12/13/2022] Open
Abstract
Extracellular matrix (ECM) deposition in the trabecular meshwork (TM) is one of the hallmarks of glaucoma, a group of human diseases and leading cause of permanent blindness. The molecular mechanisms underlying ECM deposition in the glaucomatous TM are not known, but it is presumed to be a consequence of excessive synthesis of ECM components, decreased proteolytic degradation, or both. Targeting ECM deposition might represent a therapeutic approach to restore outflow facility in glaucoma. Previous work conducted in our laboratory identified the lysosomal enzyme cathepsin B (CTSB) to be expressed on the cellular surface and to be secreted into the culture media in trabecular meshwork (TM) cells. Here, we further investigated the role of CTSB on ECM remodeling and outflow physiology in vitro and in CSTBko mice. Our results indicate that CTSB localizes in the caveolae and participates in the pericellular degradation of ECM in TM cells. We also report here a novel role of CTSB in regulating the expression of PAI-1 and TGFβ/Smad signaling in TM cells vitro and in vivo in CTSBko mice. We propose enhancing CTSB activity as a novel therapeutic target to attenuate fibrosis and ECM deposition in the glaucomatous outflow pathway.
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23
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Youngblood H, Cai J, Drewry MD, Helwa I, Hu E, Liu S, Yu H, Mu H, Hu Y, Perkumas K, Aboobakar IF, Johnson WM, Stamer WD, Liu Y. Expression of mRNAs, miRNAs, and lncRNAs in Human Trabecular Meshwork Cells Upon Mechanical Stretch. Invest Ophthalmol Vis Sci 2020; 61:2. [PMID: 32392310 PMCID: PMC7405621 DOI: 10.1167/iovs.61.5.2] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Purpose Intraocular pressure (IOP), the primary risk factor for primary open-angle glaucoma, is determined by resistance to aqueous outflow through the trabecular meshwork (TM). IOP homeostasis relies on TM responses to mechanical stretch. To model the effects of elevated IOP on the TM, this study sought to identify coding and non-coding RNAs differentially expressed in response to mechanical stretch. Methods Monolayers of TM cells from non-glaucomatous donors (n = 5) were cultured in the presence or absence of 15% mechanical stretch, 1 cycle/second, for 24 hours using a computer-controlled Flexcell unit. We profiled mRNAs and lncRNAs with stranded total RNA sequencing and microRNA (miRNA) expression with NanoString-based miRNA assays. We used two-tailed paired t-tests for mRNAs and long non-coding RNAs (lncRNAs) and the Bioconductor limma package for miRNAs. Gene ontology and pathway analyses were performed with WebGestalt. miRNA–mRNA interactions were identified using Ingenuity Pathway Analysis Integrative miRNA Target Finder software. Validation of differential expression was conducted using droplet digital PCR. Results We identified 219 mRNAs, 42 miRNAs, and 387 lncRNAs with differential expression in TM cells upon cyclic mechanical stretch. Pathway analysis indicated significant enrichment of genes involved in steroid biosynthesis, glycerolipid metabolism, and extracellular matrix–receptor interaction. We also identified several miRNA master regulators (miR-125a-5p, miR-30a-5p, and miR-1275) that regulate several mechanoresponsive genes. Conclusions To our knowledge, this is the first demonstration of the differential expression of coding and non-coding RNAs in a single set of cells subjected to cyclic mechanical stretch. Our results validate previously identified, as well as novel, genes and pathways.
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Saccà SC, Paluan F, Gandolfi S, Manni G, Cutolo CA, Izzotti A. Common aspects between glaucoma and brain neurodegeneration. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2020; 786:108323. [PMID: 33339584 DOI: 10.1016/j.mrrev.2020.108323] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 07/10/2020] [Indexed: 01/05/2023]
Abstract
Neurodegeneration can be defined as progressive cell damage to nervous system cells, and more specifically to neurons, which involves morphologic alterations and progressive loss of function until cell death. Glaucoma exhibits many aspects of neurodegenerative disease. This review examines the pathogenesis of glaucoma, comparing it with that of Alzheimer's disease (AD) and Parkinson's disease (PD), highlighting their common features. Indeed, in all three diseases there are not only the same types of pathogenic events, but also similarities of temporal cadences that determine neuronal damage. All three age-related illnesses have oxidative damage and mitochondrial dysfunction as the first pathogenic steps. The consequence of these alterations is the death of visual neurons in glaucoma, cognitive neurons in AD and regulatory motor neurons (substantia nigra) in PD. The study of these common pathogenic events (oxidative stress, mitochondrial dysfunction, protein degradation, apoptosis and autophagy) leads us to consider common therapeutic strategies for the treatment and prevention of these diseases. Also, examination of the genetic aspects of the pathways involved in neurodegenerative processes plays a key role in shedding light on the details of pathogenesis and can suggest new treatments. This review discusses the common molecular aspects involved in these three oxidative-stress and age-related diseases.
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Affiliation(s)
| | - Filippo Paluan
- Department of Health Sciences, University of Genoa, Genoa., Italy
| | - Stefano Gandolfi
- Ophthalmology Unit, Department of Biological, Biotechnological and Translational Sciences, University of Parma, Parma, Italy
| | - Gianluca Manni
- Dept. of Clinical Science and Translational Medicine, University Tor Vergata, Rome, Italy; IRCCS-Fondazione GB Bietti, Rome, Italy
| | | | - Alberto Izzotti
- IRCCS Policlinico San Martino, Genoa, Italy; Department of Experimental Medicine, University of Genoa, Genoa, Italy
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25
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Shim MS, Nettesheim A, Hirt J, Liton PB. The autophagic protein LC3 translocates to the nucleus and localizes in the nucleolus associated to NUFIP1 in response to cyclic mechanical stress. Autophagy 2020; 16:1248-1261. [PMID: 31476975 PMCID: PMC7469449 DOI: 10.1080/15548627.2019.1662584] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 08/18/2019] [Accepted: 08/28/2019] [Indexed: 12/19/2022] Open
Abstract
The trabecular meshwork (TM) is a key regulatory tissue of intraocular pressure (IOP) in the anterior chamber of eye. Dysfunction of the TM causes resistance to outflow of aqueous humor, which in turn leads to elevated IOP, a main risk factor of glaucomatous neurodegeneration. Due to variations in IOP, TM cells are continuously exposed to mechanical deformations. We previously reported activation of macroautophagy/autophagy, as one of the physiological responses elicited in TM cells following mechanical strain application. By using biochemical fractionation analysis and imaging techniques, we demonstrate here for the first time the nuclear accumulation of the autophagic marker MAP1LC3/LC3 (microtubule associated protein1 light chain 3)-II, endogenous and exogenously added (AdGFP-LC3, AdtfLC3), in response to cyclic mechanical stress (CMS). Wheat germ agglutinin (WGA) and leptomycin B treatment suggest LC3 to enter the nucleus by passive diffusion, but to exit in an XPO1/CRM1 (exportin 1)-dependent manner in human TM (hTM) cells. While blockage of nuclear export leads to accumulation of LC3 with promyelocytic leukemia (PML) bodies, nuclear LC3 localizes in the nucleolus in cells under CMS. Moreover, nuclear LC3 co-immunoprecipitated with NUFIP1, a ribosome receptor for starvation-induced ribophagy. More interestingly, we further demonstrate that NUFIP1 translocates from the nucleus to LAMP2 (lysosomal associated membrane protein 2)-positive organelles in the stretched cells without triggering ribophagy, suggesting a more general role of NUFIP1 as a selective autophagy receptor for another yet-to-be-identified target in CMS and a surveillance role of nuclear LC3 against stretch-induced damage. ABBREVIATION AdGFP: adenovirus encoding GFP; ATG: autophagy-related; BSA: bovine serum albumin; CMS: cyclic mechanical stretch; Co-IP: coimmunoprecipitation; DAPI: 4',6-diamidino-2-phenylindole; DFCs: dense fibrillar components; EM: electron microscopy; FCs: fibrillar centers; GCs: granular components; GFP: green fluorescent protein; hTM: human trabecular meshwork; HBSS: Hanks balanced salt solution; IOP: intraocular pressure; LAMP1/2: lysosomal associated membrane protein 1/2; LepB: leptomycin B; MTOR: mechanistic target of rapamacyin kinase; NES: nuclear export signals; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; NLS: nuclear localization signal; NPCs: nuclear pore complexes; NUFIP1: nuclear FMR1 interacting protein 1; NS: non-stretched; PBS: phosphate-buffered saline; PE: phosphatidylethanolamine; pfu: plaque-forming units; PML: promyelocytic leukemia; RFP: red fluorescent protein; RPS15A: ribosomal protein S15a; RPL26: ribosomal protein L26; rRNA: ribosomal RNA; SIRT1: sirtuin 1; SQSTM1/p62: sequestosome 1; tfLC3: mRFP-GFP tandem fluorescent-tagged LC3; TM: trabecular meshwork; WB: western blot; WDR36: WD repeat domain 36; WGA: wheat germ agglutinin; XPO1/CRM1: exportin 1.
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Affiliation(s)
- Myoung Sup Shim
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
| | - April Nettesheim
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
| | - Joshua Hirt
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
| | - Paloma B. Liton
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
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26
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Hill SE, Kwon MS, Martin MD, Suntharalingam A, Hazel A, Dickey CA, Gumbart JC, Lieberman RL. Stable calcium-free myocilin olfactomedin domain variants reveal challenges in differentiating between benign and glaucoma-causing mutations. J Biol Chem 2019; 294:12717-12728. [PMID: 31270212 PMCID: PMC6709634 DOI: 10.1074/jbc.ra119.009419] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 06/25/2019] [Indexed: 01/07/2023] Open
Abstract
Nonsynonymous gene mutations can be beneficial, neutral, or detrimental to the stability, structure, and biological function of the encoded protein, but the effects of these mutations are often not readily predictable. For example, the β-propeller olfactomedin domain of myocilin (mOLF) exhibits a complex interrelationship among structure(s), stability, and aggregation. Numerous mutations within mOLF are linked to glaucoma; the resulting variants are less stable, aggregation-prone, and sequestered intracellularly, causing cytotoxicity. Here, we report the first stable mOLF variants carrying substitutions in the calcium-binding site that exhibit solution characteristics indistinguishable from those of glaucoma variants. Crystal structures of these stable variants at 1.8-2.0-Å resolution revealed features that we could not predict by molecular dynamics simulations, including loss of loop structure, helix unwinding, and a blade shift. Double mutants that combined a stabilizing substitution and a selected glaucoma-causing single-point mutant rescued in vitro folding and stability defects. In the context of full-length myocilin, secretion of stable single variants was indistinguishable from that of the WT protein, and the double mutants were secreted to varying extents. In summary, our finding that mOLF can tolerate particular substitutions that render the protein stable despite a conformational switch emphasizes the complexities in differentiating between benign and glaucoma-causing variants and provides new insight into the possible biological function of myocilin.
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Affiliation(s)
- Shannon E. Hill
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Michelle S. Kwon
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Mackenzie D. Martin
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Amirthaa Suntharalingam
- Department of Molecular Medicine and Byrd Alzheimer's Research Institute, University of South Florida, Tampa, Florida 33613
| | - Anthony Hazel
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Chad A. Dickey
- Department of Molecular Medicine and Byrd Alzheimer's Research Institute, University of South Florida, Tampa, Florida 33613
| | - James C. Gumbart
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332,School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Raquel L. Lieberman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, To whom correspondence should be addressed:
School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Dr. NW, Atlanta, GA 30332-0400. E-mail:
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27
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Hernstadt DJ, Cheng J, Htoon HM, Sangtam T, Thomas A, Sng CCA. Case Series of Combined iStent Implantation and Phacoemulsification in Eyes with Primary Angle Closure Disease: One-Year Outcomes. Adv Ther 2019; 36:976-986. [PMID: 30820873 DOI: 10.1007/s12325-019-00899-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Indexed: 11/26/2022]
Abstract
PURPOSE To evaluate the safety and efficacy of combined iStent® trabecular micro-bypass device (Glaukos, Laguna Hills, CA) and phacoemulsification in eyes with primary angle closure disease. METHODS A two-center prospective interventional case series of consecutive patients with primary angle closure (PAC) or primary angle closure glaucoma (PACG) on at least one glaucoma medication, who underwent iStent implantation with cataract surgery. Postoperatively, patients were assessed on days 1 and 7, and months 1, 3, 6, and 12. The intraocular pressure (IOP), glaucoma medication use, visual acuity, and the presence of complications were assessed at each visit. Complete success was defined as IOP reduction of at least 20% without the use of glaucoma medications. RESULTS Thirty-seven eyes with angle closure disease were included in this study. At 1-year, postoperative mean IOP (14.8 ± 3.94 mmHg) was significantly decreased compared with preoperative medicated (17.5 ± 3.82 mmHg, p = 0.008) and unmedicated (24.6 ± 3.41 mmHg, p < 0.001) IOP. Complete success was achieved in 89.2% of the eyes. The number of glaucoma medications decreased from 1.49 ± 0.77 to 0.14 ± 0.48 (p < 0.001). Preoperative medicated IOP was a risk factor for failure (hazard ratio 3.45, 95% confidence interval 1.52-7.85, p = 0.003), after adjustment for age, gender, and race. The most common postoperative complications were iStent occlusion with iris (27.0%) and hyphema (18.9%). There were no sight-threatening intraoperative or postoperative complications. CONCLUSION Combined iStent implantation with cataract surgery was effective in lowering the IOP and the number of glaucoma medications for at least 12 months, with a favorable safety profile. FUNDING Glaukos Corporation; NMRC Science Translational and Applied Research (STAR) award.
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Affiliation(s)
| | - Jason Cheng
- Department of Ophthalmology, Khoo Teck Puat Hospital, Singapore, Singapore
- Vision Eye Institute, Sydney, Australia
- Department of Ophthalmology, Liverpool Hospital, Sydney, Australia
| | | | - Tiakumzuk Sangtam
- Department of Ophthalmology, Khoo Teck Puat Hospital, Singapore, Singapore
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Anoop Thomas
- Department of Ophthalmology, Khoo Teck Puat Hospital, Singapore, Singapore
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Chelvin Cheryl Agnes Sng
- Department of Ophthalmology, National University Hospital, Singapore, Singapore.
- Singapore Eye Research Institute, Singapore, Singapore.
- Moorfields Eye Hospital, London, UK.
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28
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García-Antón MT, Salazar JJ, de Hoz R, Rojas B, Ramírez AI, Triviño A, Aroca-Aguilar JD, García-Feijoo J, Escribano J, Ramírez JM. Goniodysgenesis variability and activity of CYP1B1 genotypes in primary congenital glaucoma. PLoS One 2017; 12:e0176386. [PMID: 28448622 PMCID: PMC5407778 DOI: 10.1371/journal.pone.0176386] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 04/10/2017] [Indexed: 11/19/2022] Open
Abstract
Mutations in the CYP1B1 gene are currently the main known genetic cause of primary congenital glaucoma (PCG), a leading cause of blindness in children. Here, we analyze for the first time the CYP1B1 genotype activity and the microscopic and clinical phenotypes in human PCG. Surgical pieces from trabeculectomy from patients with PCG (n = 5) and sclerocorneal rims (n = 3) from cadaver donors were processed for transmission electron microscopy. Patients were classified into three groups depending on goniodysgenesis severity, which was influenced by CYP1B1 enzymatic activity. The main histological changes observed in the outflow pathway of patients with PCG and mutations in CYP1B1 were: i) underdeveloped collector channels and the Schlemm’s canal; ii) abnormal insertion of the ciliary muscle; iii) death of the trabecular endothelial cells. Our findings could be useful in improving treatment strategy of PCG associated with CYP1B1 mutations.
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Affiliation(s)
- María T. García-Antón
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain
- Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain
| | - Juan J. Salazar
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain
- Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain
- Departamento de Oftalmología y ORL, Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Madrid, Spain
| | - Rosa de Hoz
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain
- Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain
- Departamento de Oftalmología y ORL, Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Madrid, Spain
| | - Blanca Rojas
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain
- Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain
- Departamento de Oftalmología y ORL, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain
| | - Ana I. Ramírez
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain
- Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain
- Departamento de Oftalmología y ORL, Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Madrid, Spain
| | - Alberto Triviño
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain
- Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain
- Departamento de Oftalmología y ORL, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain
| | - José-Daniel Aroca-Aguilar
- Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain
- Área de Genética, Facultad de Medicina/Instituto de Investigación en Discapacidades Neurológicas (IDINE), Universidad de Castilla-La Mancha, Albacete, Spain
| | - Julián García-Feijoo
- Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain
- Servicio de Oftalmología, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain
| | - Julio Escribano
- Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain
- Área de Genética, Facultad de Medicina/Instituto de Investigación en Discapacidades Neurológicas (IDINE), Universidad de Castilla-La Mancha, Albacete, Spain
| | - José M. Ramírez
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain
- Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain
- Departamento de Oftalmología y ORL, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain
- * E-mail:
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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: 39] [Impact Index Per Article: 5.6] [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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30
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Moazzeni H, Akbari MT, Yazdani S, Elahi E. Expression of CXCL6 and BBS5 that may be glaucoma relevant genes is regulated by PITX2. Gene 2016; 593:76-83. [PMID: 27520585 DOI: 10.1016/j.gene.2016.08.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 07/31/2016] [Accepted: 08/08/2016] [Indexed: 12/26/2022]
Abstract
The transcription factor PITX2 is implicated in glaucoma pathology. In an earlier study we had used microarray analysis to identify genes in the trabecular meshwork (TM) that are affected by knock down of PITX2. Here, those studies were pursued to identify genes that are direct targets of PITX2 and that may be relevant to glaucoma. Initially, bioinformatics tools were used to select among the genes that had been affected by PITX2 knock down those that have PITX2 binding sites and that may be involved in glaucoma related functions. Subsequently, the effect of PITX2 was tested using the dual luciferase assay in four cell cultures including two primary TM cultures co-transfected with vectors containing promoter fragments of six candidate genes upstream of a luciferase gene and a vector that expressed PITX2. Finally, the effect of PITX2 on endogenous expression of two genes was assessed by over expression and knock down of PITX2 in TM cells. Thirty four genes were found to contain PITX2 binding sites in their putative promoter regions, and 16 were found to be associated with TM-specific and/or glaucoma associated functions. Results of dual luciferase assays confirmed that two of six genes tested were directly targeted by PITX2. The two genes were CXCL6 (chemokine (C-X-C motif) ligand 6) and BBS5 (Bardet-Biedl syndrome 5). Over expression and knock down of PITX2 showed that this transcription factor affects endogenous expression of these two genes in TM cells. CXCL6 encodes a pro-inflammatory cytokine, and many studies have suggested that cytokines and other immune system functions are involved in glaucoma pathogenesis. BBS5 is a member of the BBS family of genes that affect ciliary functions, and ciliary bodies in the anterior chamber of the eye produce the aqueous fluid that affects intraocular pressure. Immune related functions and intraocular pressure are both important components of glaucoma pathology. The role of PITX2 in glaucoma may be mediated partly by regulating the expression of CXCL6 and BBS5 and thus affecting immune functions and intraocular pressure.
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Affiliation(s)
- Hamidreza Moazzeni
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, P.O. Box. 14115-331, Tehran, Iran
| | - Mohammad Taghi Akbari
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, P.O. Box. 14115-331, Tehran, Iran.
| | - Shahin Yazdani
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Elahe Elahi
- School of Biology, College of Science, University of Tehran, Tehran, Iran; Department of Biotechnology, College of Science, University of Tehran, Tehran, Iran.
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Saccà SC, Gandolfi S, Bagnis A, Manni G, Damonte G, Traverso CE, Izzotti A. From DNA damage to functional changes of the trabecular meshwork in aging and glaucoma. Ageing Res Rev 2016; 29:26-41. [PMID: 27242026 DOI: 10.1016/j.arr.2016.05.012] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 05/25/2016] [Accepted: 05/26/2016] [Indexed: 12/24/2022]
Abstract
Glaucoma is a degenerative disease of the eye. Both the anterior and posterior segments of the eye are affected, extensive damage being detectable in the trabecular meshwork and the inner retina-central visual pathway complex. Oxidative stress is claimed to be mainly responsible for molecular damage in the anterior chamber. Indeed, oxidation harms the trabecular meshwork, leading eventually to endothelial cell decay, tissue malfunction, subclinical inflammation, changes in the extracellular matrix and cytoskeleton, altered motility, reduced outflow facility and (ultimately) increased IOP. Moreover, free radicals are involved in aging and can be produced in the brain (as well as in the eye) as a result of ischemia, leading to oxidation of the surrounding neurons. Glaucoma-related cell death occurs by means of apoptosis, and apoptosis is triggered by oxidative stress via (a) mitochondrial damage, (b) inflammation, (c) endothelial dysregulation and dysfunction, and (d) hypoxia. The proteomics of the aqueous humor is significantly altered in glaucoma as a result of oxidation-induced trabecular damage. Those proteins whose aqueous humor levels are increased in glaucoma are biomarkers of trabecular meshwork impairment. Their diffusion from the anterior to the posterior segment of the eye may be relevant in the cascade of events triggering apoptosis in the inner retinal layers, including the ganglion cells.
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Affiliation(s)
- Sergio Claudio Saccà
- IRCCS San Martino University Hospital, Department of Neuroscience and Sense Organs, San Martino Hospital, Ophthalmology Unit, Viale Benedetto XV, 16132 Genoa, Italy.
| | - Stefano Gandolfi
- Ophthalmology Unit, Department of Biological, Biotechnological and Translational Sciences, University of Parma, Parma, Italy
| | - Alessandro Bagnis
- University of Genoa, Eye Clinic, Department of Neuroscience and Sense Organs, Viale Benedetto XV, 5, 16148 Genoa, Italy
| | - Gianluca Manni
- Dept. of Clinical Science and Translational Medicine, University Tor Vergata, Rome, Italy
| | - Gianluca Damonte
- Dept. of Experimental Medicine, Section of Biochemistry and Center of Excellence for Biomedical Research, University of Genoa, Viale Benedetto XV 1, 16132 Genoa, Italy
| | - Carlo Enrico Traverso
- University of Genoa, Eye Clinic, Department of Neuroscience and Sense Organs, Viale Benedetto XV, 5, 16148 Genoa, Italy
| | - Alberto Izzotti
- Mutagenesis Unit, IRCCS San Martino University Hospital, IST National Institute for Cancer Research, Department of Health Sciences, University of Genoa, Via A. Pastore 1, Genoa I-16132, Italy
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The exit strategy: Pharmacological modulation of extracellular matrix production and deposition for better aqueous humor drainage. Eur J Pharmacol 2016; 787:32-42. [PMID: 27112663 DOI: 10.1016/j.ejphar.2016.04.048] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 04/20/2016] [Accepted: 04/22/2016] [Indexed: 01/28/2023]
Abstract
Primary open angle glaucoma (POAG) is an optic neuropathy and an irreversible blinding disease. The etiology of glaucoma is not known but numerous risk factors are associated with this disease including aging, elevated intraocular pressure (IOP), race, myopia, family history and use of steroids. In POAG, the resistance to the aqueous humor drainage is increased leading to elevated IOP. Lowering the resistance and ultimately the IOP has been the only way to slow disease progression and prevent vision loss. The primary drainage pathway comprising of the trabecular meshwork (TM) is made up of relatively large porous beams surrounded by extracellular matrix (ECM). Its juxtacanalicular tissue (JCT) or the cribriform meshwork is made up of cells embedded in dense ECM. The JCT is considered to offer the major resistance to the aqueous humor outflow. This layer is adjacent to the endothelial cells forming Schlemm's canal, which provides approximately 10% of the outflow resistance. The ECM in the TM and the JCT undergoes continual remodeling to maintain normal resistance to aqueous humor outflow. It is believed that the TM is a major contributor of ECM proteins and evidence points towards increased ECM deposition in the outflow pathway in POAG. It is not clear how and from where the ECM components emerge to hinder the normal aqueous humor drainage. This review focuses on the involvement of the ECM in ocular hypertension and glaucoma and the mechanisms by which various ocular hypotensive drugs, both current and emerging, target ECM production, remodeling, and deposition.
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Itakura T, Peters DM, Fini ME. Glaucomatous MYOC mutations activate the IL-1/NF-κB inflammatory stress response and the glaucoma marker SELE in trabecular meshwork cells. Mol Vis 2015; 21:1071-84. [PMID: 26396484 PMCID: PMC4575906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2015] [Accepted: 09/15/2015] [Indexed: 11/14/2022] Open
Abstract
PURPOSE Activation of the IL-1/NF-κB inflammatory stress pathway and induction of SELE expression in the trabecular meshwork (TBM) is a marker for high-tension glaucomas of diverse etiology. Pathway activation stimulates aqueous outflow and protects against oxidative stress, but may be damaging in the long-term. MYOC mutations have been causally linked to high-tension forms of primary open angle glaucoma (POAG). This study investigated a possible link between MYOC mutations and activation of the IL-1/NF-κB pathway and expression of SELE. METHODS We constructed MYOC expression vectors with mutations at sites that cause POAG. Mutations (Q368X, Y437H, A427T) were selected to represent proteins with differing POAG-causing potency (Q368X > Y437H > A427T) and intracellular retention behavior (Q368X and Y437H retained, A427T released). The constructs were made in two different kinds of vectors; one a plasmid designed for transient transfection (pCMV6), and one a doxycycline-inducible lentiviral vector (pSLIK) for stable cell transduction. The immortalized human trabecular meshwork line TM-1 was used for all expression studies. Expression of IL1A mRNA was determined by reverse transcription (RT)-PCR, as well as a set of five other genes associated with signaling pathways linked to glaucoma: IL1B and IL6 (NF-κB pathway), TGFB2 and ACTA2 (TGF-β pathway) and FOXO1 (E2F1 apoptotic pathway). An ELISA was used to quantify IL1A protein released into culture media. To quantify intracellular NF-κB activity, we transiently transfected stably transduced cell lines with a luciferase expression vector under control of the IL8 promoter (containing an NF-κB response element). RESULTS Transiently expressed wild-type MYOC was released into cell culture media, whereas mutant MYOCs Q368X and Y437H remained within cells. Both mutant MYOCs activated the IL-1/ NF-κB pathway, significantly stimulating expression of IL1A and IL1B. However Y437H, which causes a severe glaucoma phenotype, was less effective than Q368X, which causes a moderate glaucoma phenotype. In addition, the retained mutants stimulated expression of stress response genes ACTA2 and FOXO1. Unexpectedly, wild-type MYOC significantly decreased expression of IL6 and TGFB2, to approximately half of the control levels, and expression of IL1B and ACTA2 was also slightly decreased. Induction of MYOC mutants Q368X and Y437H in stably transduced cell lines significantly stimulated the level of IL1A protein released into culture media. Once again however, the effect of the severe MYOC mutant Y437H was less than the effect of the moderate MYOC mutant Q368X. In contrast, induced expression of the intracellularly retained mutant MYOC A427T or wild-type MYOC did not change the amount of IL1A protein in culture media. Induction of Y437H MYOC plus IL1A treatment increased NF-κB activity by 25% over IL1A alone. In contrast, induction of Q368X or A427T plus IL1A treatment did not significantly affect NF-κB activity over IL1A alone. However, wild-type MYOC expression inhibited IL1A-stimulated NF-κB activity. We also observed that endogenous MYOC expression was induced by IL1A in TM-1 cells and primary TBM cell cultures. SELE was co-expressed with MYOC in the primary cell lines. CONCLUSIONS These results indicate that POAG-causing MYOC mutants activate the IL-1/NF-κB pathway, with activation levels correlated with intracellular retention of the protein, but not POAG-causing potency. Unexpectedly, it was also discovered that wild-type MYOC inhibits activation of the IL-1/NF-κB pathway, and that activation of the IL-1/NF-κB pathway stimulates expression of MYOC. This is the first evidence that glaucoma-causing MYOC mutants can activate the inflammatory response and that wild-type MYOC has anti-inflammatory activity.
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Affiliation(s)
- Tatsuo Itakura
- USC Institute for Genetic Medicine, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA
| | - Donna M. Peters
- Departments of Pathology & Laboratory Medicine and Ophthalmology & Visual Sciences, University of Wisconsin, Madison, WI
| | - M. Elizabeth Fini
- USC Institute for Genetic Medicine, USC Eye Institute, and Departments of Cell & Neurobiology and Ophthalmology, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA
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Liton PB. The autophagic lysosomal system in outflow pathway physiology and pathophysiology. Exp Eye Res 2015; 144:29-37. [PMID: 26226231 DOI: 10.1016/j.exer.2015.07.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 07/06/2015] [Accepted: 07/22/2015] [Indexed: 12/19/2022]
Abstract
Malfunction of the trabecular meshwork (TM)/schlemm's canal (SC) conventional outflow pathway is associated with elevated intraocular pressure (IOP) and, therefore, increased risk of developing glaucoma, a potentially blinding disease affecting more than 70 million people worldwide. This TM/SC tissue is subjected to different types of stress, including mechanical, oxidative, and phagocytic stress. Long-term exposure to these stresses is believed to lead to a progressive accumulation of damaged cellular and tissue structures causing permanent alterations in the tissue physiology, and contribute to the pathologic increase in aqueous humor (AH) outflow resistance. Autophagy is emerging as an essential cellular survival mechanism against a variety of stressors. In addition to performing basal functions, autophagy acts as a cellular survival pathway and represents an essential mechanism by which organisms can adapt to acute stress conditions and repair stress-induced damage. A decline in autophagy has been observed in most tissues with aging and has been considered responsible, at least in part, for the accumulation of damaged cellular components in almost all tissues of aging organisms. Dysfunction in the autophagy pathway is associated with several human diseases, from infectious diseases to cancer and neurodegeneration. In this review, we will summarize our current knowledge of the emerging roles of autophagy in outflow tissue physiology and pathophysiology, including novel evidence suggesting compromised autophagy in the glaucomatous outflow pathway.
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Affiliation(s)
- Paloma B Liton
- Duke University, Department of Ophthalmology, Durham, NC, USA.
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[Structural alterations during the course of glaucoma disease]. Ophthalmologe 2015; 112:410-7. [PMID: 25701239 DOI: 10.1007/s00347-014-3152-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
BACKGROUND Structural changes in the course of glaucoma disease affect the trabecular meshwork and ciliary body in addition to the optic disc as the primary site of glaucoma damage. OBJECTIVES Latest results from experimental studies, animal models and measurements in human eyes are presented and discussed. RESULTS The presenting scenario is complex with age, biochemical and mechanical stress factors leading to subsequent, irreversible tissue change in the trabecular meshwork and cribriform plate of the optic nerve, resulting in neuronal tissue loss. CONCLUSION Knowledge of these changes will be the key for future glaucoma therapies.
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Porter K, Hirt J, Stamer WD, Liton PB. Autophagic dysregulation in glaucomatous trabecular meshwork cells. Biochim Biophys Acta Mol Basis Dis 2014; 1852:379-85. [PMID: 25483712 DOI: 10.1016/j.bbadis.2014.11.021] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 11/12/2014] [Accepted: 11/30/2014] [Indexed: 01/07/2023]
Abstract
Primary open angle glaucoma (POAG) is a degenerative disease commonly associated with aging and elevated intraocular pressure (IOP). Higher resistance to aqueous humor (AH) outflow through the trabecular meshwork (TM) generates the elevated IOP in POAG; unfortunately the underlying molecular mechanisms responsible for elevated resistance are unknown. It is widely accepted, however, that differences between normal and POAG TM tissues are presumably a consequence of cellular dysfunction. Here, we investigated the autophagic function and response to chronic oxidative stress in TM cells isolated from glaucomatous and age-matched donor eyes. Glaucomatous TM cells showed elevated senescence-associated-beta-galactosidase (SA-β-Gal) and cellular lipofuscin, together with decreased steady-state levels of LC3B-II, decreased levels of pRPS6K-T389 and reduced proteolysis of long-live proteins. Moreover, the glaucomatous cultures failed to activate autophagy when exposed to hyperoxic conditions. These results strongly suggest mTOR-dependent dysregulation of the autophagic pathway in cells isolated from the glaucomatous TM. Such dysregulated autophagic capacity can have a detrimental impact in outflow pathway tissue, i.e. mechanotransduction, and thus represent an important factor contributing to the progression of the disease.
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Affiliation(s)
- Kristine Porter
- Duke University, Department of Ophthalmology, Durham, NC, USA
| | - Joshua Hirt
- Duke University, Department of Ophthalmology, Durham, NC, USA
| | - W Daniel Stamer
- Duke University, Department of Ophthalmology, Durham, NC, USA
| | - Paloma B Liton
- Duke University, Department of Ophthalmology, Durham, NC, USA.
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Goyal A, Srivastava A, Sihota R, Kaur J. Evaluation of Oxidative Stress Markers in Aqueous Humor of Primary Open Angle Glaucoma and Primary Angle Closure Glaucoma Patients. Curr Eye Res 2014; 39:823-9. [PMID: 24912005 DOI: 10.3109/02713683.2011.556299] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Acott TS, Kelley MJ, Keller KE, Vranka JA, Abu-Hassan DW, Li X, Aga M, Bradley JM. Intraocular pressure homeostasis: maintaining balance in a high-pressure environment. J Ocul Pharmacol Ther 2014; 30:94-101. [PMID: 24401029 DOI: 10.1089/jop.2013.0185] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Although glaucoma is a relatively common blinding disease, most people do not develop glaucoma. A robust intraocular pressure (IOP) homeostatic mechanism keeps ocular pressures within relatively narrow acceptable bounds throughout most peoples' lives. The trabecular meshwork and/or Schlemm's canal inner wall cells respond to sustained IOP elevation and adjust the aqueous humor outflow resistance to restore IOP to acceptable levels. It appears that the cells sense IOP elevations as mechanical stretch or distortion of the actual outflow resistance and respond by initiating a complex extracellular matrix (ECM) turnover process that takes several days to complete. Although considerable information pertinent to this process is available, many aspects of the IOP homeostatic process remain to be elucidated. Components and mechanisms beyond ECM turnover could also be relevant to IOP homeostasis, but will not be addressed in detail here. Known aspects of the IOP homeostasis process as well as possible ways that it might function and impact glaucoma are discussed.
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Affiliation(s)
- Ted S Acott
- Casey Eye Institute, Oregon Health & Science University , Portland, Oregon
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Famili A, Ammar DA, Kahook MY. Ethyl pyruvate treatment mitigates oxidative stress damage in cultured trabecular meshwork cells. Mol Vis 2013; 19:1304-9. [PMID: 23805037 PMCID: PMC3692399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 06/07/2013] [Indexed: 11/06/2022] Open
Abstract
PURPOSE Oxidative stress plays a key role in the pathophysiology of glaucoma. This study was designed to assess ethyl pyruvate (EP) as a novel antioxidative agent in cultured human trabecular meshwork (hTM) cells. METHODS Primary hTM cells were cultured on collagen matrices. Tolerance to EP was assessed at various concentrations using fluorescent vital dyes (live/dead) and metabolic (1-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays. After the candidate doses were identified, cells received either preincubation with EP before hydrogen peroxide stressing or pre- and coincubation with EP before and during stressing. Live/dead and metabolic activity assays were used to quantify oxidative damage. RESULTS Cultured hTM cells were well tolerant of EP concentrations at or below 10 mM while higher doses showed significant levels of cytotoxicity. In the peroxide stress assays, samples that received pre- and cotreatment with all concentrations of EP showed significantly increased cell survival and maintenance of metabolic activity. However, samples that received only pretreatment did not show a significant increase in survival rates and lost nearly all metabolic activity after peroxide-induced stressing. CONCLUSIONS This work suggests that EP is a potent antioxidant that is well tolerated by hTM cells; however, EP's potential as a therapeutic agent for glaucoma is limited by its inability to enhance endogenous antioxidant capacity. A continuous drug delivery system may be needed to realize the full therapeutic potential of EP for treatment of glaucoma.
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Affiliation(s)
- Amin Famili
- Department of Bioengineering, University of Colorado Denver, Aurora, CO
| | - David A. Ammar
- Department of Ophthalmology, University of Colorado Denver, MS F731 Rocky Mountain Lions Eye Institute, Aurora, CO
| | - Malik Y. Kahook
- Department of Ophthalmology, University of Colorado Denver, MS F731 Rocky Mountain Lions Eye Institute, Aurora, CO
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Yang X, Liu B, Bai Y, Chen M, Li Y, Chen M, Wei Y, Ge J, Zhuo Y. Elevated pressure downregulates ZO-1 expression and disrupts cytoskeleton and focal adhesion in human trabecular meshwork cells. Mol Vis 2011; 17:2978-85. [PMID: 22128243 PMCID: PMC3224831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Accepted: 11/09/2011] [Indexed: 11/02/2022] Open
Abstract
PURPOSE To investigate the effect of elevated hydrostatic pressure on the expression and distribution of zonula occludens-1 (ZO-1), and its effect on cytoskeleton and focal adhesion in immortal human trabecular meshwork cells (iHTM) and glaucomatous human trabecular meshwork cells (GTM(3)). METHODS iHTM and GTM(3) were exposed to 60 mmHg hydrostatic pressure for 6, 12, and 24 h. As a control, the cells were incubated simultaneously in a conventional incubator. Morphology changes were observed with an inverted microscope. The expression of ZO-1was examined with western blot, and the distribution of ZO-1 was assessed by immunofluorescence. Actin cytoskeleton and focal adhesion (vinculin) were also assessed by immunofluorescence. Data were analyzed with commercial data analysis software and a p<0.05 was considered to be statistically significant. RESULTS There was no evident morphology change after 24 h culture in 60 mmHg pressure in iHTM and GTM(3). However, in both iHTM and GTM(3), elevated pressure attenuated the expression of ZO-1 at 12 h and 24 h, detected by western blot. Meanwhile, high pressure disrupted the organization of ZO-1, actin cytoskeleton, and vinculin, assessed by immunofluorescence. When comparing iHTM with GTM(3), the distribution of ZO-1 and vinculin in GTM(3) was not as regular as that in iHTM. After exposuring in elevated pressure, the changes in GTM(3) were more obvious than that in iHTM. CONCLUSIONS Sustained pressure elevation may directly damage trabecular meshwork cells by injuring ZO-1, cytoskeleton, and foal adhesions. And GTM(3) was more susceptible to damage than iHTM. We suggest that elevated pressure seems to be not only the results of damaged TM, but also an important factor for the injury of TM cells, stop or reverse the process may help developing new target for the treatment of primary open angle glaucoma (POAG).
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Affiliation(s)
- Xuejiao Yang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Bingqian Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yujing Bai
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China,Key Laboratory of Vision Loss and Restoration, Ministry of Education, Department of Ophthalmology, Peking University People’s Hospital, Beijing, China
| | - Min Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China,Department of Opthalmology, the second affiliated hospital of Zhejiang University, Hangzhou, Zhejiang, China
| | - Yiqing Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Mengfei Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yantao Wei
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jian Ge
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yehong Zhuo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
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Chowdhury UR, Bahler CK, Hann CR, Chang M, Resch ZT, Romero MF, Fautsch MP. ATP-sensitive potassium (KATP) channel activation decreases intraocular pressure in the anterior chamber of the eye. Invest Ophthalmol Vis Sci 2011; 52:6435-42. [PMID: 21743021 DOI: 10.1167/iovs.11-7523] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE. ATP-sensitive potassium channel (K(ATP)) openers target key cellular events, many of which have been implicated in glaucoma. The authors sought to determine whether K(ATP) channel openers influence outflow facility in human anterior segment culture and intraocular pressure (IOP) in vivo. METHODS. Anterior segments from human eyes were placed in perfusion organ culture and treated with the K(ATP) channel openers diazoxide, nicorandil, and P1075 or the K(ATP) channel closer glyburide (glibenclamide). The presence, functionality, and specificity of K(ATP) channels were determined by RT-PCR, immunohistochemistry, and inside-out patch clamp in human trabecular meshwork (TM) tissue or primary cultures of normal human trabecular meshwork (NTM) cells. The effect of diazoxide on IOP in anesthetized Brown Norway rats was measured with a rebound tonometer. RESULTS. K(ATP) channel openers increased outflow facility in human anterior segments (0.14 ± 0.02 to 0.26 ± 0.09 μL/min/mm Hg; P < 0.001) compared with fellow control eyes (0.22 ± 0.11 to 0.21 ± 0.11 μL/min/mm Hg; P > 0.5). The effect was reversible, with outflow facility returning to baseline after drug removal. The addition of glyburide inhibited diazoxide from increasing outflow facility. Electrophysiology confirmed the presence and specificity of functional K(ATP) channels. K(ATP) channel subunits K(ir)6.1, K(ir)6.2, SUR2A, and SUR2B were expressed in TM and NTM cells. In vivo, diazoxide significantly lowered IOP in Brown Norway rats. CONCLUSIONS. Functional K(ATP) channels are present in the trabecular meshwork. When activated by K(ATP) channel openers, these channels increase outflow facility through the trabecular outflow pathway in human anterior segment organ culture and decrease IOP in Brown Norway rat eyes.
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Zenkel M, Lewczuk P, Jünemann A, Kruse FE, Naumann GOH, Schlötzer-Schrehardt U. Proinflammatory cytokines are involved in the initiation of the abnormal matrix process in pseudoexfoliation syndrome/glaucoma. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 176:2868-79. [PMID: 20395431 DOI: 10.2353/ajpath.2010.090914] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Pseudoexfoliation (PEX) syndrome, which is an age-related, generalized elastotic matrix process, currently represents the most common identifiable risk factor for open-angle glaucoma. Dysregulated expression of proinflammatory cytokines has been implicated in the initiation of various fibrotic disorders and in the pathophysiology of glaucoma. Here we investigated the presence, expression, regulation, and functional significance of proinflammatory cytokines in eyes with early and late stages of PEX syndrome/glaucoma in comparison with normal and glaucomatous control eyes using multiplex bead analysis, immunoassays, real-time PCR, Western blotting, immunohistochemistry, and cell culture models. Early stages of PEX syndrome were characterized by approximately threefold (P < 0.005) elevated interleukin (IL)-6 and IL-8 levels in the aqueous humor and a concomitant approximately twofold (P < 0.001) increase in mRNA expression levels in anterior segment tissues as compared with controls. In contrast, late stages of PEX syndrome/glaucoma did not differ significantly from controls. IL-6, IL-6 receptor, and phospho-signal transducer and activator of transcription 3 could be mainly localized to walls of iris vessels and to the nonpigmented epithelium of ciliary processes. IL-6 and IL-8 were significantly up-regulated by ciliary epithelial cells in response to hypoxia or oxidative stress in vitro, whereas IL-6, but not IL-8, induced the expression of transforming growth factor-beta1 and elastic fiber proteins. These findings support a role for a stress-induced, spatially, and temporally restricted subclinical inflammation in the onset of the fibrotic matrix process characteristic of PEX syndrome/glaucoma.
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Affiliation(s)
- Matthias Zenkel
- Department of Ophthalmology, University of Erlangen-Nürnberg, Schwabachanlage 6, D-91054 Erlangen, Germany.
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Shyam R, Shen X, Yue BY, Wentz-Hunter KK. Wnt gene expression in human trabecular meshwork cells. Mol Vis 2010; 16:122-9. [PMID: 20111673 PMCID: PMC2812481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Accepted: 01/22/2010] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The aim of this study was to examine the expression of genes related to the Wnt signaling pathway, such as beta-catenin (CTNNB1) and secreted frizzled-related protein-1 (sFRP1), in human trabecular meshwork (TM) cells. In addition, the effect of oxidative stress on Wnt signaling was evaluated. METHODS All experiments were conducted using second- or third-passaged human TM cells. cDNA was prepared from total RNA extracted from cells by means of reverse transcription. PCR was then performed to determine the presence of Wnt genes. For oxidative stress, TM cells were treated with 1 mM of H(2)O(2) for 30 min. Actin staining was carried out to verify cell response to oxidative stress. Western blotting was used to measure Wnt-related protein levels after H(2)O(2) treatment. RESULTS Positive PCR products were detected for a total of 25 Wnt and Wnt-related genes in human TM cells. Most of the genes identified belonged to the Wnt/beta-catenin pathway. Members of the beta-catenin-independent noncanonical pathways were also found. Oxidative stress did not result in significant changes in beta-catenin and sFRP1 protein levels. CONCLUSIONS Genes related to canonical and noncanonical Wnt pathways are expressed in human TM cells. It appears that all three Wnt pathways are operative in the TM system. Oxidative stress, while thought to play a role in the development of glaucoma, had little effect on the Wnt activity in TM cells.
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Affiliation(s)
- Rajalekshmy Shyam
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago College of Medicine, Chicago, IL,Roosevelt University, Department of Biological, Chemical and Physical Sciences, Chicago, IL
| | - Xiang Shen
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago College of Medicine, Chicago, IL
| | - Beatrice Y.J.T. Yue
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago College of Medicine, Chicago, IL
| | - Kelly K. Wentz-Hunter
- Roosevelt University, Department of Biological, Chemical and Physical Sciences, Chicago, IL
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Baetz NW, Hoffman EA, Yool AJ, Stamer WD. Role of aquaporin-1 in trabecular meshwork cell homeostasis during mechanical strain. Exp Eye Res 2009; 89:95-100. [PMID: 19268465 DOI: 10.1016/j.exer.2009.02.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Revised: 01/14/2009] [Accepted: 02/24/2009] [Indexed: 10/21/2022]
Abstract
Aquaporin-1 (AQP1) channels are expressed by trabecular meshwork (TM) and Schlemm's canal cells of the conventional outflow pathway where fluid movement is predominantly paracellular, suggesting a non-canonical role for AQP1. We hypothesized that AQP1 functions to protect TM cells during periods of mechanical strain. To test this idea, primary cultures of confluent human TM cells on Bioflex membranes were exposed to static and cyclic stretch for 8 and 24h using the Flexcell system. AQP1 expression in TM cells was assessed by SDS-PAGE and Western blot using anti-AQP1 IgGs. AQP1 protein bands were analyzed using densitometry and normalized to beta-actin expression. Cell damage was monitored by measuring lactate dehydrogenase (LDH) and histone deacetylase appearance in conditioned media. Recombinant expression of AQP1 in TM cell cultures was facilitated by transduction with adenovirus. Results show that AQP1 expression significantly increased 2-fold with 10% static stretch and 3.5-fold with 20% static stretch at 8h (n=4, p<0.05) and 24h (n=6, p<0.05). While histone deacetylase levels were unaffected by treatments, release of LDH from TM cells was the most profound at the 20% static stretch level (n=4, p<0.05). Significantly, cells were refractory to the 20% static stretch level when AQP1 expression was increased to near tissue levels. Analysis of LDH release with respect to AQP1 expression revealed an inverse linear relationship (r(2)=0.7780). Taken together, AQP1 in human TM appears to serve a protective role by facilitating improved cell viability during conditions of mechanical strain.
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Affiliation(s)
- N W Baetz
- Department of Cell Biology and Anatomy, University of Arizona, Tucson, AZ, USA
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