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Kempuraj D, Mohan RR. Blast injury: Impact to the cornea. Exp Eye Res 2024; 244:109915. [PMID: 38677709 PMCID: PMC11179966 DOI: 10.1016/j.exer.2024.109915] [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: 01/02/2024] [Revised: 04/03/2024] [Accepted: 04/24/2024] [Indexed: 04/29/2024]
Abstract
Visual disorders are common even after mild traumatic brain injury (mTBI) or blast exposure. The cost of blast-induced vision loss in civilians, military personnel, and veterans is significant. The visual consequences of blasts associated with TBI are elusive. Active military personnel and veterans report various ocular pathologies including corneal disorders post-combat blasts. The wars and conflicts in Afghanistan, Iraq, Syria, and Ukraine have significantly increased the number of corneal and other ocular disorders among military personnel and veterans. Binocular vision, visual fields, and other visual functions could be impaired following blast-mediated TBI. Blast-associated injuries can cause visual disturbances, binocular system problems, and visual loss. About 25% of veterans exposed to blasts report corneal injury. Blast exposure induces corneal edema, corneal opacity, increased corneal thickness, damage of corneal epithelium, corneal abrasions, and stromal and endothelial abnormality including altered endothelial density, immune cell infiltration, corneal neovascularization, Descemet membrane rupture, and increased pain mediators in animal models and the blast-exposed military personnel including veterans. Immune response exacerbates blast-induced ocular injury. TBI is associated with dry eyes and pain in veterans. Subjects exposed to blasts that cause TBI should undergo immediate clinical visual and ocular examinations. Delayed visual care may lead to progressive vision loss, lengthening/impairing rehabilitation and ultimately may lead to permanent vision problems and blindness. Open-field blast exposure could induce corneal injuries and immune responses in the cornea. Further studies are warranted to understand corneal pathology after blast exposure. A review of current advancements in blast-induced corneal injury will help elucidate novel targets for potential therapeutic options. This review discusses the impact of blast exposure-associated corneal disorders.
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Affiliation(s)
- Duraisamy Kempuraj
- Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, United States; One-Health Vision Research Program, Departments of Veterinary Medicine & Surgery and Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States
| | - Rajiv R Mohan
- Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, United States; One-Health Vision Research Program, Departments of Veterinary Medicine & Surgery and Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States; Mason Eye Institute, School of Medicine, University of Missouri, Columbia, MO, United States.
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2
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Melnyk S, Bollag WB. Aquaporins in the Cornea. Int J Mol Sci 2024; 25:3748. [PMID: 38612559 PMCID: PMC11011575 DOI: 10.3390/ijms25073748] [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: 02/20/2024] [Revised: 03/18/2024] [Accepted: 03/21/2024] [Indexed: 04/14/2024] Open
Abstract
The cornea is an avascular, transparent tissue that allows light to enter the visual system. Accurate vision requires proper maintenance of the cornea's integrity and structure. Due to its exposure to the external environment, the cornea is prone to injury and must undergo proper wound healing to restore vision. Aquaporins (AQPs) are a family of water channels important for passive water transport and, in some family members, the transport of other small molecules; AQPs are expressed in all layers of the cornea. Although their functions as water channels are well established, the direct function of AQPs in the cornea is still being determined and is the focus of this review. AQPs, primarily AQP1, AQP3, and AQP5, have been found to play an important role in maintaining water homeostasis, the corneal structure in relation to proper hydration, and stress responses, as well as wound healing in all layers of the cornea. Due to their many functions in the cornea, the identification of drug targets that modulate the expression of AQPs in the cornea could be beneficial to promote corneal wound healing and restore proper function of this tissue crucial for vision.
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Affiliation(s)
- Samuel Melnyk
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA;
| | - Wendy B. Bollag
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA;
- Charlie Norwood Department of Veterans Affairs Medical Center, Augusta, GA 30904, USA
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3
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Kreida S, Roche JV, Missel JW, Al-Jubair T, Hagströmer CJ, Wittenbecher V, Linse S, Gourdon P, Törnroth-Horsefield S. The role of phosphorylation in calmodulin-mediated gating of human AQP0. Biochem J 2024; 481:17-32. [PMID: 38032258 PMCID: PMC10903448 DOI: 10.1042/bcj20230158] [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: 05/02/2023] [Revised: 11/17/2023] [Accepted: 11/30/2023] [Indexed: 12/01/2023]
Abstract
Aquaporin-0 (AQP0) is the main water channel in the mammalian lens and is involved in accommodation and maintaining lens transparency. AQP0 binds the Ca2+-sensing protein calmodulin (CaM) and this interaction is believed to gate its water permeability by closing the water-conducting pore. Here, we express recombinant and functional human AQP0 in Pichia pastoris and investigate how phosphorylation affects the interaction with CaM in vitro as well as the CaM-dependent water permeability of AQP0 in proteoliposomes. Using microscale thermophoresis and surface plasmon resonance technology we show that the introduction of the single phospho-mimicking mutations S229D and S235D in AQP0 reduces CaM binding. In contrast, CaM interacts with S231D with similar affinity as wild type, but in a different manner. Permeability studies of wild-type AQP0 showed that the water conductance was significantly reduced by CaM in a Ca2+-dependent manner, whereas AQP0 S229D, S231D and S235D were all locked in an open state, insensitive to CaM. We propose a model in which phosphorylation of AQP0 control CaM-mediated gating in two different ways (1) phosphorylation of S229 or S235 abolishes binding (the pore remains open) and (2) phosphorylation of S231 results in CaM binding without causing pore closure, the functional role of which remains to be elucidated. Our results suggest that site-dependent phosphorylation of AQP0 dynamically controls its CaM-mediated gating. Since the level of phosphorylation increases towards the lens inner cortex, AQP0 may become insensitive to CaM-dependent gating along this axis.
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Affiliation(s)
- Stefan Kreida
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | | | - Julie Winkel Missel
- Department of Biomedical Sciences, Copenhagen University, Copenhagen, Denmark
| | - Tamim Al-Jubair
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | | | | | - Sara Linse
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | - Pontus Gourdon
- Department of Biomedical Sciences, Copenhagen University, Copenhagen, Denmark
- Department of Experimental Medical Science, Lund University, Lund, Sweden
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Zhang K, Di G, Bai Y, Liu A, Bian W, Chen P. Aquaporin 5 in the eye: Expression, function, and roles in ocular diseases. Exp Eye Res 2023; 233:109557. [PMID: 37380095 DOI: 10.1016/j.exer.2023.109557] [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: 01/05/2023] [Revised: 05/26/2023] [Accepted: 06/25/2023] [Indexed: 06/30/2023]
Abstract
As a water channel protein, aquaporin 5 (AQP5) is essential for the maintenance of the normal physiological functions of ocular tissues. This review provides an overview of the expression and function of AQP5 in the eye and discusses their role in related eye diseases. Although AQP5 plays a vital role in ocular functions, such as maintaining corneal and lens transparency, regulating water movement, and maintaining homeostasis, some of its functions in ocular tissues are still unclear. Based on the key role of AQP5 in eye function, this review suggests that in the future, eye diseases may be treated by regulating the expression of aquaporin.
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Affiliation(s)
- Kaier Zhang
- Department of Human Anatomy, Histology and Embryology, School of Basic Medicine, Qingdao University, Qingdao, 266071, Shandong Province, China
| | - Guohu Di
- Department of Human Anatomy, Histology and Embryology, School of Basic Medicine, Qingdao University, Qingdao, 266071, Shandong Province, China
| | - Ying Bai
- Department of Human Anatomy, Histology and Embryology, School of Basic Medicine, Qingdao University, Qingdao, 266071, Shandong Province, China
| | - Anxu Liu
- Department of Human Anatomy, Histology and Embryology, School of Basic Medicine, Qingdao University, Qingdao, 266071, Shandong Province, China
| | - Wenhan Bian
- Department of Human Anatomy, Histology and Embryology, School of Basic Medicine, Qingdao University, Qingdao, 266071, Shandong Province, China
| | - Peng Chen
- Department of Human Anatomy, Histology and Embryology, School of Basic Medicine, Qingdao University, Qingdao, 266071, Shandong Province, China; Clinical Laboratory, Qingdao Central Hospital, The Second Affiliated Hospital of Medical College of Qingdao University, Qingdao, 266042, Shandong Province, China.
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5
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Bhend ME, Kempuraj D, Sinha NR, Gupta S, Mohan RR. Role of aquaporins in corneal healing post chemical injury. Exp Eye Res 2023; 228:109390. [PMID: 36696947 PMCID: PMC9975064 DOI: 10.1016/j.exer.2023.109390] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 12/31/2022] [Accepted: 01/19/2023] [Indexed: 01/23/2023]
Abstract
Aquaporins (AQPs) are transmembrane water channel proteins that regulate the movement of water through the plasma membrane in various tissues including cornea. The cornea is avascular and has specialized microcirculatory mechanisms for homeostasis. AQPs regulate corneal hydration and transparency for normal vision. Currently, there are 13 known isoforms of AQPs that can be subclassified as orthodox AQPs, aquaglyceroporins (AQGPs), or supraquaporins (SAQPs)/unorthodox AQPs. AQPs are implicated in keratocyte function, inflammation, edema, angiogenesis, microvessel proliferation, and the wound-healing process in the cornea. AQPs play an important role in wound healing by facilitating the movement of corneal stromal keratocytes by squeezing through tight stromal matrix and narrow extracellular spaces to the wound site. Deficiency of AQPs can cause reduced concentration of hepatocyte growth factor (HGF) leading to reduced epithelial proliferation, reduced/impaired keratocyte migration, reduced number of keratocytes in the injury site, delayed and abnormal wound healing process. Dysregulated AQPs cause dysfunction in osmolar homeostasis as well as wound healing mechanisms. The cornea is a transparent avascular tissue that constitutes the anterior aspect of the outer covering of the eye and aids in two-thirds of visual light refraction. Being the outermost layer of the eye, the cornea is prone to injury. Of the 13 AQP isoforms, AQP1 is expressed in the stromal keratocytes and endothelial cells, and AQP3 and AQP5 are expressed in epithelial cells in the human cornea. AQPs can facilitate wound healing through aid in cellular migration, proliferation, migration, extracellular matrix (ECM) remodeling and autophagy mechanism. Corneal wound healing post-chemical injury requires an integrative and coordinated activity of the epithelium, stromal keratocytes, endothelium, ECM, and a battery of cytokines and growth factors to restore corneal transparency. If the chemical injury is mild, the cornea will heal with normal clarity, but severe injuries can lead to partial and/or permanent loss of corneal functions. Currently, the role of AQPs in corneal wound healing is poorly understood in the context of chemical injury. This review discusses the current literature and the role of AQPs in corneal homeostasis, wound repair, and potential therapeutic target for acute and chronic corneal injuries.
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Affiliation(s)
- Madeline E Bhend
- Department of Ophthalmology, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA; School of Medicine, University of South Carolina, Columbia, SC, USA; Mason Eye Institute, School of Medicine, University of Missouri, Columbia, MO, USA
| | - Duraisamy Kempuraj
- Department of Ophthalmology, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA; Institute for Neuro-Immune Medicine, Dr. Kiran C. Patel College of Osteopathic Medicine, Nova Southeastern University, Ft. Lauderdale, FL, USA
| | - Nishant R Sinha
- Department of Ophthalmology, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA; Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, USA
| | - Suneel Gupta
- Department of Ophthalmology, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA; Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, USA
| | - Rajiv R Mohan
- Department of Ophthalmology, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA; Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, USA; Mason Eye Institute, School of Medicine, University of Missouri, Columbia, MO, USA.
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Wang RX, Li N, Chen XY. Ultrasound cyclo-plasty for moderate glaucoma: Eighteen-month results from a prospective study. Front Med (Lausanne) 2022; 9:1009273. [PMID: 36590936 PMCID: PMC9801481 DOI: 10.3389/fmed.2022.1009273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 11/08/2022] [Indexed: 12/23/2022] Open
Abstract
Purpose To evaluate the long-term clinical efficacy of ultrasound cyclo-plasty (UCP) in the treatment of moderate glaucoma and molecular effects in animal experiments. Methods An 18-month clinical study was conducted among 32 patients with moderate glaucoma. The primary outcome was surgical success, defined as a reduction in intraocular pressure (IOP) of greater than or equal to 20% from the baseline and an IOP value of greater than 5 mmHg at the last follow-up. The secondary outcomes were related to the quality of life, complications, and mean IOP value at each follow-up. In the animal experiment, 20 New Zealand rabbits were used to establish a high-IOP model and implement UCP. The distribution of aquaporin 4 (AQP4) in the ciliary body and the tissue changes under electron microscopy were observed after surgery. Results The mean patient IOP decreased from 34.9 ± 4.9 mmHg before surgery to 23.5 ± 5.2 mmHg at 18 months after UCP. No vision loss occurred in any patient. Some patients had postoperative complications, but the symptoms were mild and disappeared within 3 months after the surgery. Most patients had good postoperative quality of life. Histology showed that AQP4 remained in the ciliary muscle after UCP, and only the bilayered epithelial cells showed coagulative necrosis. Furthermore, electron microscopic observation revealed the destruction of ciliary process cells covered by ultrasound after UCP. Conclusion UCP is associated with mild postoperative reactions and the mild treatment of ciliary tissue and is a safe and effective method for reducing IOP in moderate glaucoma.
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Affiliation(s)
- Rui-Xue Wang
- The Affiliated Xuzhou Municipal Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China,Department of Ophthalmology, Xuzhou First People’s Hospital, Xuzhou, Jiangsu, China
| | - Ning Li
- Department of Ophthalmology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China
| | - Xiao-Ya Chen
- The Affiliated Xuzhou Municipal Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China,Department of Ophthalmology, Xuzhou First People’s Hospital, Xuzhou, Jiangsu, China,*Correspondence: Xiao-Ya Chen,
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7
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Gletten RB, Cantrell LS, Bhattacharya S, Schey KL. Lens Aquaporin-5 Inserts Into Bovine Fiber Cell Plasma Membranes Via Unconventional Protein Secretion. Invest Ophthalmol Vis Sci 2022; 63:5. [PMID: 35816045 PMCID: PMC9284464 DOI: 10.1167/iovs.63.8.5] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Purpose To spatially map aquaporin-5 (AQP5) expression in the bovine lens, molecularly characterize cytoplasmic AQP5-containing vesicles in the outer cortex, and elucidate AQP5 membrane trafficking mechanisms. Methods Immunofluorescence was performed on bovine lens cryosections using AQP5, TOMM20, COX IV, calnexin, LC3B, Sec22β, LIMP-2, and connexin 50 antibodies and the membrane dye CM-DiI. AQP5 plasma membrane insertion was defined via line expression profile analysis. Transmission electron microscopy (TEM) was performed on bovine lens sections to examine cytoplasmic organelle morphology and subcellular localization in cortical fiber cells. Bovine lenses were treated with 10-nM bafilomycin A1 or 0.1% dimethyl sulfoxide vehicle control for 24 hours in ex vivo culture to determine changes in AQP5 plasma membrane expression. Results Immunofluorescence analysis revealed cytoplasmic AQP5 expression in lens epithelial cells and differentiating fiber cells. In the lens cortex, complete AQP5 plasma membrane insertion occurs at r/a = 0.951 ± 0.005. AQP5-containing cytoplasmic vesicles are spheroidal in morphology with linear extensions, express TOMM20, and contain LC3B and LIMP-2, but not Sec22β, as fiber cells mature. TEM analysis revealed complex vesicular assemblies with congruent subcellular localization to AQP5-containing cytoplasmic vesicles. AQP5-containing cytoplasmic vesicles appear to dock with the plasma membrane. Bafilomycin A1 treatment reduced AQP5 plasma membrane expression by 27%. Conclusions AQP5 localizes to spheroidal, linear cytoplasmic vesicles in the differentiating bovine lens fiber cells. During fiber cell differentiation, these vesicles incorporate LC3B and presumably fuse with LIMP-2–positive lysosomes. Our data suggest that AQP5 to the plasma membrane through lysosome-associated unconventional protein secretion, a novel mechanism of AQP5 trafficking.
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Affiliation(s)
- Romell B Gletten
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, United States
| | - Lee S Cantrell
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, United States
| | - Sujoy Bhattacharya
- Department of Ophthalmology and Visual Sciences, Vanderbilt University, Nashville, Tennessee, United States
| | - Kevin L Schey
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, United States
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Huang OS, Seet LF, Ho HW, Chu SW, Narayanaswamy A, Perera SA, Husain R, Aung T, Wong TT. Altered Iris Aquaporin Expression and Aqueous Humor Osmolality in Glaucoma. Invest Ophthalmol Vis Sci 2021; 62:34. [PMID: 33616622 PMCID: PMC7910645 DOI: 10.1167/iovs.62.2.34] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Aquaporins (AQPs) facilitate transmembrane osmotic water transport and may play a role in iris fluid conductivity, which is implicated in the pathophysiology of glaucoma. In this study, we compared the iris expression of AQPs and aqueous osmolality between primary angle closure glaucoma (PACG), primary open-angle glaucoma (POAG), and nonglaucoma eyes. Methods AQP1-5 transcripts from a cohort of 36 PACG, 34 POAG and 26 nonglaucoma irises were measured by quantitative real-time PCR. Osmolality of aqueous humor from another cohort of 49 PACG, 50 POAG, and 50 nonglaucoma eyes were measured using an osmometer. The localization of AQP1 in both glaucoma and nonglaucoma irises was determined by immunofluorescent analysis. Results Of the five AQP genes evaluated, AQP1 and AQP2 transcripts were significantly upregulated in both PACG (3.48- and 8.07-fold, respectively) and POAG (3.12- and 11.58-fold, respectively) irises relative to nonglaucoma counterparts. The aqueous osmolalities of PACG (303.68 mmol/kg) and POAG (300.79 mmol/kg) eyes were significantly lower compared to nonglaucoma eyes (312.6 mmol/kg). There was no significant difference in expression of AQP transcripts or aqueous osmolality between PACG and POAG eyes. Conclusions PACG and POAG eyes featured significant increase in AQP1 and AQP2 expression in the iris and reduced aqueous osmolality compared to nonglaucoma eyes. These findings suggest that the iris may be involved in altered aqueous humor dynamics in glaucoma pathophysiology. Because PACG did not differ from POAG in both properties studied, it is likely that they are common to glaucoma disease in general.
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Affiliation(s)
- Olivia S Huang
- Singapore National Eye Centre, Singapore.,Duke-NUS Medical School, Singapore
| | - Li-Fong Seet
- Singapore Eye Research Institute, Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Duke-NUS Medical School, Singapore
| | | | | | | | - Shamira A Perera
- Singapore National Eye Centre, Singapore.,Singapore Eye Research Institute, Singapore.,Duke-NUS Medical School, Singapore
| | - Rahat Husain
- Singapore National Eye Centre, Singapore.,Singapore Eye Research Institute, Singapore.,Duke-NUS Medical School, Singapore
| | - Tin Aung
- Singapore National Eye Centre, Singapore.,Singapore Eye Research Institute, Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Duke-NUS Medical School, Singapore
| | - Tina T Wong
- Singapore National Eye Centre, Singapore.,Singapore Eye Research Institute, Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Duke-NUS Medical School, Singapore.,School of Materials Science and Engineering, Nanyang Technological University, Singapore
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Lamagna B, Ciaramella P, Lamagna F, Di Loria A, Brunetti A, Pelagalli A. Aquaporin 1 (AQP1) Expression in Healthy Dog Tears. Animals (Basel) 2020; 10:ani10050820. [PMID: 32397372 PMCID: PMC7278581 DOI: 10.3390/ani10050820] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 12/28/2022] Open
Abstract
Simple Summary The characterisation of tear proteins is very important for scientists and clinicians, as it enhances their understanding of ocular physiological phenomena that sometimes evolve into diseases. Recently, ophthalmic research has been focused on aquaporins (AQPs), a family of water channel proteins that are largely ubiquitous in body tissues and are known for their role in water and small solute transport across cell membranes. Based on AQPs’ presumable role in the eye, the aim of the present study was to investigate the expression of aquaporin-1 (AQP1) by Western blot analysis in canine eye tears. To this end, we collected tears from both eyes of 15 healthy dogs by employing two tear collection methods: Schirmer tear strips (STS) and ophthalmic sponges (OS). Moreover, ocular parameters such as Schirmer tear test 1 (STT 1), intraocular pressure (IOP), and tear film break up time (BUT) were measured, and fluorescein and lissamine green staining were performed to uncover possible correlations among the aforementioned parameters. Our results showed that the expression of AQP1 in tears collected by both methods and expressed as multiple bands (measured by densitometry) was higher for the tears collected by OS than for those collected by STS. This work forms the basis of future studies aiming to understand and establish the involvement of AQPs in the production and secretion of tears. Abstract Aquaporins (AQPs) are a family of thirteen membrane proteins that play an essential role in the transport of fluids across the cell plasma membrane. Recently, the expression of AQPs in different ocular tissues and their involvement in the pathophysiology of eye diseases, have garnered attention. Considering that literature on AQP expression in the lacrimal glands and their secretion is scarce, we aimed to characterise AQP1 expression in the tears of healthy dogs using two tear collection methods (Schirmer tear strips (STS) and ophthalmic sponges (OS)). Fifteen healthy dogs, free of ophthalmic diseases, were included in the study. Tear collection was performed by using STS in one eye and OS in the other. After the extraction of proteins from the tears, the expression of AQP1 was analysed by Western blotting. AQP1 was expressed as a band of 28 kDa. In addition, differences were observed in the expression of AQP1 and in the correlation between tear volume and protein concentration, in tears collected by the two different methods. Our results suggest that AQP1 has a specific role in tear secretion; further research is required to assess its particular role in the function of the ocular surface in eye physiology and pathology.
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Affiliation(s)
- Barbara Lamagna
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, 80137 Naples, Italy; (B.L.); (P.C.); (F.L.); (A.D.L.)
| | - Paolo Ciaramella
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, 80137 Naples, Italy; (B.L.); (P.C.); (F.L.); (A.D.L.)
| | - Francesco Lamagna
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, 80137 Naples, Italy; (B.L.); (P.C.); (F.L.); (A.D.L.)
| | - Antonio Di Loria
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, 80137 Naples, Italy; (B.L.); (P.C.); (F.L.); (A.D.L.)
| | - Arturo Brunetti
- Department of Advanced Biomedical Sciences, University of Naples Federico II, 80131 Naples, Italy;
| | - Alessandra Pelagalli
- Department of Advanced Biomedical Sciences, University of Naples Federico II, 80131 Naples, Italy;
- Institute of Biostructures and Bioimaging (IBB), National Research Council (CNR), 80131 Naples, Italy
- Correspondence:
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Systemic Hypertension Effects on the Ciliary Body and Iris. An Immunofluorescence Study with Aquaporin 1, Aquaporin 4, and Na⁺, K⁺ ATPase in Hypertensive Rats. Cells 2018; 7:cells7110210. [PMID: 30428541 PMCID: PMC6262422 DOI: 10.3390/cells7110210] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 11/08/2018] [Accepted: 11/09/2018] [Indexed: 11/16/2022] Open
Abstract
Aquaporin 1 (AQP1) and aquaporin 4 (AQP4) have been identified in the eye as playing an essential role in the formation of the aqueous humor along with the Na+/K+ ATPase pump. Different authors have described the relationship between blood pressure, aqueous humor production, and intraocular pressure with different conclusions, with some authors supporting a positive correlation between blood pressure and intraocular pressure while others disagree. The aim of this work was to study the effect of high blood pressure on the proteins involved in the production of aqueous humor in the ciliary body (CB) and iris. For this purpose, we used the eyes of spontaneously hypertensive rats (SHR) and their control Wistar-Kyoto rats (WKY). Immunofluorescence was performed in different eye structures to analyze the effects of hypertension in the expression of AQP1, AQP4, and the Na+/K+ ATPase α1 and α2 subunits. The results showed an increase in AQP1 and Na+/K+ ATPase α1 and a decrease in AQP4 and Na+/K+ ATPase α2 in the CB of SHR, while an increase in AQP4 and no significant differences in AQP1 were found in the iris. Therefore, systemic hypertension produced changes in the proteins implicated in the movement of water in the CB and iris that could influence the production rate of aqueous humor, which would be affected depending on the duration of systemic hypertension.
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