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Rudraraju M, Shan S, Liu F, Tyler J, Caldwell RB, Somanath PR, Narayanan SP. Pharmacological Modulation of β-Catenin Preserves Endothelial Barrier Integrity and Mitigates Retinal Vascular Permeability and Inflammation. J Clin Med 2023; 12:7145. [PMID: 38002758 PMCID: PMC10672253 DOI: 10.3390/jcm12227145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/01/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
Compromised blood-retinal barrier (BRB) integrity is a significant factor in ocular diseases like uveitis and retinopathies, leading to pathological vascular permeability and retinal edema. Adherens and tight junction (AJ and TJ) dysregulation due to retinal inflammation plays a pivotal role in BRB disruption. We investigated the potential of ICG001, which inhibits β-catenin-mediated transcription, in stabilizing cell junctions and preventing BRB leakage. In vitro studies using human retinal endothelial cells (HRECs) showed that ICG001 treatment improved β-Catenin distribution within AJs post lipopolysaccharide (LPS) treatment and enhanced monolayer barrier resistance. The in vivo experiments involved a mouse model of LPS-induced ocular inflammation. LPS treatment resulted in increased albumin leakage from retinal vessels, elevated vascular endothelial growth factor (VEGF) and Plasmalemmal Vesicle-Associated Protein (PLVAP) expression, as well as microglia and macroglia activation. ICG001 treatment (i.p.) effectively mitigated albumin leakage, reduced VEGF and PLVAP expression, and reduced the number of activated microglia/macrophages. Furthermore, ICG001 treatment suppressed the surge in inflammatory cytokine synthesis induced by LPS. These findings highlight the potential of interventions targeting β-Catenin to enhance cell junction stability and improve compromised barrier integrity in various ocular inflammatory diseases, offering hope for better management and treatment options.
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Affiliation(s)
- Madhuri Rudraraju
- Clinical and Experimental Therapeutics, Clinical and Administrative Pharmacy Department, College of Pharmacy, University of Georgia, Augusta, GA 30912, USA
- Research and Development, Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
| | - Shengshuai Shan
- Clinical and Experimental Therapeutics, Clinical and Administrative Pharmacy Department, College of Pharmacy, University of Georgia, Augusta, GA 30912, USA
- Research and Development, Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
- Vision Discovery Institute, Augusta University, Augusta, GA 30912, USA
| | - Fang Liu
- Clinical and Experimental Therapeutics, Clinical and Administrative Pharmacy Department, College of Pharmacy, University of Georgia, Augusta, GA 30912, USA
- Research and Development, Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
- Vision Discovery Institute, Augusta University, Augusta, GA 30912, USA
| | - Jennifer Tyler
- Clinical and Experimental Therapeutics, Clinical and Administrative Pharmacy Department, College of Pharmacy, University of Georgia, Augusta, GA 30912, USA
| | - Ruth B. Caldwell
- Research and Development, Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
- Vision Discovery Institute, Augusta University, Augusta, GA 30912, USA
- Vascular Biology Center, Augusta University, Augusta, GA 30912, USA
| | - Payaningal R. Somanath
- Clinical and Experimental Therapeutics, Clinical and Administrative Pharmacy Department, College of Pharmacy, University of Georgia, Augusta, GA 30912, USA
- Research and Development, Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
- Vision Discovery Institute, Augusta University, Augusta, GA 30912, USA
- Vascular Biology Center, Augusta University, Augusta, GA 30912, USA
| | - S. Priya Narayanan
- Clinical and Experimental Therapeutics, Clinical and Administrative Pharmacy Department, College of Pharmacy, University of Georgia, Augusta, GA 30912, USA
- Research and Development, Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
- Vision Discovery Institute, Augusta University, Augusta, GA 30912, USA
- Vascular Biology Center, Augusta University, Augusta, GA 30912, USA
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2
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Uğurlu N, Erdal E, Malekghasemi S, Demirbilek M. Effectiveness of carbonic anhydrase inhibitor loaded nanoparticles in the treatment of diabetic retinopathy. Biomed Phys Eng Express 2023; 10:015002. [PMID: 36758224 DOI: 10.1088/2057-1976/acba9d] [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: 08/23/2022] [Accepted: 02/09/2023] [Indexed: 02/11/2023]
Abstract
Diabetic Retinopathy (DRP) is a disease consisting of all the structural and functional changes that develop in the retinal layer of the eye due to diabetes. DRP is the most important cause of blindness between the ages of 20-74 in the world, and the most successful standard treatment option in the treatment of DRP is intravitreal injections. To synthesize acetazolamide loaded nanoparticles to be applied intravitreal treatment of DRP and to examine thein vitroefficacy of the nanoparticles. ACZ loaded PHBV nanoparticles (PHBV-ACZ NPs) formulations were prepared. Nanoparticles with a particle size of 253.20 ± 0.55 nm. A DRP model was established and characterized in HRMEC cells. The effect of the nanoparticles on permeability has been investigated and carrier proteins in BRB due to the development of DRP has been investigated. To establish thein vitroDRP model, HRMEC was stimulated with Recombinant human 165 Vascular Endothelial Growth Factor (VEGF), thereby temporarily reducing the expression levels of endothelial junction proteins, increasing the number of intercellular spaces in the monolayers of HRMECs. It was determined that after the cells were exposed to Carbonic anhydrase inhibitors (CAI) loaded nanoparticles, permeability decreased and protein expression increased.
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Affiliation(s)
- Nagihan Uğurlu
- Ankara Yıldırım Beyazıt University, Faculty of Medicine, Department of Ophthalmology, Advanced Technologies Application and Research Center, Ankara, Turkey
- Ministry of Health, Ankara City Hospital, Ophthalmology Clinic, Ankara, Turkey
| | - Ebru Erdal
- Ankara Yıldırım Beyazıt University, Faculty of Medicine, Advanced Technologies Application and Research Center, Ankara, Turkey
| | - Soheil Malekghasemi
- Hacettepe University, Department of Bioengineering, Graduate School of Science and Engineering, Ankara, Turkey
| | - Murat Demirbilek
- Ankara Haci Bayram Veli University, Biology Department, Ankara, Turkey
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3
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Denzer L, Muranyi W, Schroten H, Schwerk C. The role of PLVAP in endothelial cells. Cell Tissue Res 2023; 392:393-412. [PMID: 36781482 PMCID: PMC10172233 DOI: 10.1007/s00441-023-03741-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 01/18/2023] [Indexed: 02/15/2023]
Abstract
Endothelial cells play a major part in the regulation of vascular permeability and angiogenesis. According to their duty to fit the needs of the underlying tissue, endothelial cells developed different subtypes with specific endothelial microdomains as caveolae, fenestrae and transendothelial channels which regulate nutrient exchange, leukocyte migration, and permeability. These microdomains can exhibit diaphragms that are formed by the endothelial cell-specific protein plasmalemma vesicle-associated protein (PLVAP), the only known protein component of these diaphragms. Several studies displayed an involvement of PLVAP in diseases as cancer, traumatic spinal cord injury, acute ischemic brain disease, transplant glomerulopathy, Norrie disease and diabetic retinopathy. Besides an upregulation of PLVAP expression within these diseases, pro-angiogenic or pro-inflammatory responses were observed. On the other hand, loss of PLVAP in knockout mice leads to premature mortality due to disrupted homeostasis. Generally, PLVAP is considered as a major factor influencing the permeability of endothelial cells and, finally, to be involved in the regulation of vascular permeability. Following these observations, PLVAP is debated as a novel therapeutic target with respect to the different vascular beds and tissues. In this review, we highlight the structure and functions of PLVAP in different endothelial types in health and disease.
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Affiliation(s)
- Lea Denzer
- Department of Pediatrics, Pediatric Infectious Diseases, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Walter Muranyi
- Department of Pediatrics, Pediatric Infectious Diseases, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Horst Schroten
- Department of Pediatrics, Pediatric Infectious Diseases, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Christian Schwerk
- Department of Pediatrics, Pediatric Infectious Diseases, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
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4
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Mugisho OO, Aryal J, Shome A, Lyon H, Acosta ML, Green CR, Rupenthal ID. Orally Delivered Connexin43 Hemichannel Blocker, Tonabersat, Inhibits Vascular Breakdown and Inflammasome Activation in a Mouse Model of Diabetic Retinopathy. Int J Mol Sci 2023; 24:3876. [PMID: 36835288 PMCID: PMC9961562 DOI: 10.3390/ijms24043876] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/10/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
Diabetic retinopathy (DR), a microvascular complication of diabetes, is associated with pronounced inflammation arising from the activation of a nucleotide-binding and oligomerization domain-like receptor (NLR) protein 3 (NLRP3) inflammasome. Cell culture models have shown that a connexin43 hemichannel blocker can prevent inflammasome activation in DR. The aim of this study was to evaluate the ocular safety and efficacy of tonabersat, an orally bioavailable connexin43 hemichannel blocker, to protect against DR signs in an inflammatory non-obese diabetic (NOD) DR mouse model. For retina safety studies, tonabersat was applied to retinal pigment epithelial (ARPE-19) cells or given orally to control NOD mice in the absence of any other stimuli. For efficacy studies, either tonabersat or a vehicle was given orally to the inflammatory NOD mouse model two hours before an intravitreal injection of pro-inflammatory cytokines, interleukin-1 beta, and tumour necrosis factor-alpha. Fundus and optical coherence tomography images were acquired at the baseline as well as at 2- and 7-day timepoints to assess microvascular abnormalities and sub-retinal fluid accumulation. Retinal inflammation and inflammasome activation were also assessed using immunohistochemistry. Tonabersat did not have any effect on ARPE-19 cells or control NOD mouse retinas in the absence of other stimuli. However, the tonabersat treatment in the inflammatory NOD mice significantly reduced macrovascular abnormalities, hyperreflective foci, sub-retinal fluid accumulation, vascular leak, inflammation, and inflammasome activation. These findings suggest that tonabersat may be a safe and effective treatment for DR.
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Affiliation(s)
- Odunayo O. Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand; (O.O.M.); (J.A.); (A.S.); (H.L.); (I.D.R.)
| | - Jyoti Aryal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand; (O.O.M.); (J.A.); (A.S.); (H.L.); (I.D.R.)
| | - Avik Shome
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand; (O.O.M.); (J.A.); (A.S.); (H.L.); (I.D.R.)
| | - Heather Lyon
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand; (O.O.M.); (J.A.); (A.S.); (H.L.); (I.D.R.)
| | - Monica L. Acosta
- School of Optometry and Vision Science, University of Auckland, Auckland 1023, New Zealand;
| | - Colin R. Green
- Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand
| | - Ilva D. Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand; (O.O.M.); (J.A.); (A.S.); (H.L.); (I.D.R.)
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5
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Goncalves A, Antonetti DA. Transgenic animal models to explore and modulate the blood brain and blood retinal barriers of the CNS. Fluids Barriers CNS 2022; 19:86. [PMID: 36320068 PMCID: PMC9628113 DOI: 10.1186/s12987-022-00386-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 10/03/2022] [Indexed: 11/18/2022] Open
Abstract
The unique environment of the brain and retina is tightly regulated by blood-brain barrier and the blood-retinal barrier, respectively, to ensure proper neuronal function. Endothelial cells within these tissues possess distinct properties that allow for controlled passage of solutes and fluids. Pericytes, glia cells and neurons signal to endothelial cells (ECs) to form and maintain the barriers and control blood flow, helping to create the neurovascular unit. This barrier is lost in a wide range of diseases affecting the central nervous system (CNS) and retina such as brain tumors, stroke, dementia, and in the eye, diabetic retinopathy, retinal vein occlusions and age-related macular degeneration to name prominent examples. Recent studies directly link barrier changes to promotion of disease pathology and degradation of neuronal function. Understanding how these barriers form and how to restore these barriers in disease provides an important point for therapeutic intervention. This review aims to describe the fundamentals of the blood-tissue barriers of the CNS and how the use of transgenic animal models led to our current understanding of the molecular framework of these barriers. The review also highlights examples of targeting barrier properties to protect neuronal function in disease states.
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Affiliation(s)
- Andreia Goncalves
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, 1000 Wall St Rm, Ann Arbor, MI, 7317, USA
| | - David A Antonetti
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, 1000 Wall St Rm, Ann Arbor, MI, 7317, USA.
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Brinks J, van Dijk EHC, Klaassen I, Schlingemann RO, Kielbasa SM, Emri E, Quax PHA, Bergen AA, Meijer OC, Boon CJF. Exploring the choroidal vascular labyrinth and its molecular and structural roles in health and disease. Prog Retin Eye Res 2021; 87:100994. [PMID: 34280556 DOI: 10.1016/j.preteyeres.2021.100994] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/04/2021] [Accepted: 07/07/2021] [Indexed: 12/14/2022]
Abstract
The choroid is a key player in maintaining ocular homeostasis and plays a role in a variety of chorioretinal diseases, many of which are poorly understood. Recent advances in the field of single-cell RNA sequencing have yielded valuable insights into the properties of choroidal endothelial cells (CECs). Here, we review the role of the choroid in various physiological and pathophysiological mechanisms, focusing on the role of CECs. We also discuss new insights regarding the phenotypic properties of CECs, CEC subpopulations, and the value of measuring transcriptomics in primary CEC cultures derived from post-mortem eyes. In addition, we discuss key phenotypic, structural, and functional differences that distinguish CECs from other endothelial cells such as retinal vascular endothelial cells. Understanding the specific clinical and molecular properties of the choroid will shed new light on the pathogenesis of the broad clinical range of chorioretinal diseases such as age-related macular degeneration, central serous chorioretinopathy and other diseases within the pachychoroid spectrum, uveitis, and diabetic choroidopathy. Although our knowledge is still relatively limited with respect to the clinical features and molecular pathways that underlie these chorioretinal diseases, we summarise new approaches and discuss future directions for gaining new insights into these sight-threatening diseases and highlight new therapeutic strategies such as pluripotent stem cell‒based technologies and gene therapy.
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Affiliation(s)
- J Brinks
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - E H C van Dijk
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - I Klaassen
- Ocular Angiogenesis Group, Departments of Ophthalmology and Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
| | - R O Schlingemann
- Ocular Angiogenesis Group, Departments of Ophthalmology and Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands; Department of Ophthalmology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands; Department of Ophthalmology, University of Lausanne, Jules Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
| | - S M Kielbasa
- Department of Medical Statistics and Bioinformatics, Leiden University Medical Center, Leiden, the Netherlands
| | - E Emri
- Department of Clinical Genetics, Section of Ophthalmogenetics, Amsterdam University Medical Centers, Amsterdam, the Netherlands
| | - P H A Quax
- Department of Vascular Surgery, Leiden University Medical Center, Leiden, the Netherlands; Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - A A Bergen
- Department of Clinical Genetics, Section of Ophthalmogenetics, Amsterdam University Medical Centers, Amsterdam, the Netherlands
| | - O C Meijer
- Department of Medicine, Division of Endocrinology and Metabolism, Leiden University Medical Center, Leiden, the Netherlands
| | - C J F Boon
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands; Department of Ophthalmology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands.
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7
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Wijk A, Canning P, Heijningen RP, Vogels IM, Noorden CJ, Klaassen I, Schlingemann RO. Glucocorticoids exert differential effects on the endothelium in an in vitro model of the blood-retinal barrier. Acta Ophthalmol 2019; 97:214-224. [PMID: 30168271 DOI: 10.1111/aos.13909] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 08/03/2018] [Indexed: 12/25/2022]
Abstract
PURPOSE Glucocorticoids (GCs) are used as treatment in diabetic macular oedema, a condition caused by blood-retinal barrier (BRB) disruption. The proposed mechanisms by which GCs reduce macular oedema are indirect anti-inflammatory effects and inhibition of VEGF production, but direct effects on the BRB endothelium may be equally important. Here, we investigated direct effects of GCs on the endothelium to understand the specific pathways of GC action, to enable development of novel therapeutics lacking the adverse side-effects of the presently used GCs. METHODS Primary bovine retinal endothelial cells (BRECs) were grown on Transwell inserts and treated with hydrocortisone (HC), dexamethasone (Dex) or triamcinolone acetonide (TA). Molecular barrier integrity of the BRB was determined by mRNA and protein expression, and barrier function was assessed using permeability assays. In addition, we investigated whether TA was able to prevent barrier disruption after stimulation with VEGF or cytokines. RESULTS Treatment of BRECs with GCs resulted in upregulation of tight junction mRNA (claudin-5, occludin, ZO-1) and protein (claudin-5 and ZO-1). In functional assays, only TA strengthened the barrier function by reducing endothelial permeability. Moreover, TA was able to prevent cytokine-induced permeability in human retinal endothelial cells and VEGF-induced expression of plasmalemma vesicle-associated protein (PLVAP), a key player in VEGF-induced retinal vascular leakage. CONCLUSION Glucocorticoids have differential effects in an experimental in vitro BRB model. TA is the most potent in improving barrier function, both at the molecular and functional levels, and TA prevents VEGF-induced expression of PLVAP.
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Affiliation(s)
- Anne‐Eva Wijk
- Departments of Ophthalmology and Medical Biology Amsterdam UMC University of Amsterdam Ocular Angiogenesis Group Amsterdam Cardiovascular Sciences Amsterdam Neuroscience Amsterdam The Netherlands
| | - Paul Canning
- The Wellcome‐Wolfson Institute for Experimental Medicine School of Medicine Dentistry and Biomedical Sciences Queen's University Belfast Belfast UK
| | - Rutger P. Heijningen
- Departments of Ophthalmology and Medical Biology Amsterdam UMC University of Amsterdam Ocular Angiogenesis Group Amsterdam Cardiovascular Sciences Amsterdam Neuroscience Amsterdam The Netherlands
| | - Ilse M.C. Vogels
- Departments of Ophthalmology and Medical Biology Amsterdam UMC University of Amsterdam Ocular Angiogenesis Group Amsterdam Cardiovascular Sciences Amsterdam Neuroscience Amsterdam The Netherlands
| | - Cornelis J.F. Noorden
- Departments of Ophthalmology and Medical Biology Amsterdam UMC University of Amsterdam Ocular Angiogenesis Group Amsterdam Cardiovascular Sciences Amsterdam Neuroscience Amsterdam The Netherlands
- Department of Genetic Toxicology and Cancer Biology National Institute of Biology Ljubljana Slovenia
| | - Ingeborg Klaassen
- Departments of Ophthalmology and Medical Biology Amsterdam UMC University of Amsterdam Ocular Angiogenesis Group Amsterdam Cardiovascular Sciences Amsterdam Neuroscience Amsterdam The Netherlands
| | - Reinier O. Schlingemann
- Departments of Ophthalmology and Medical Biology Amsterdam UMC University of Amsterdam Ocular Angiogenesis Group Amsterdam Cardiovascular Sciences Amsterdam Neuroscience Amsterdam The Netherlands
- Department of Ophthalmology University of Lausanne Jules Gonin Eye Hospital Lausanne Switzerland
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8
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van der Wijk AE, Wisniewska-Kruk J, Vogels IMC, van Veen HA, Ip WF, van der Wel NN, van Noorden CJF, Schlingemann RO, Klaassen I. Expression patterns of endothelial permeability pathways in the development of the blood-retinal barrier in mice. FASEB J 2019; 33:5320-5333. [PMID: 30698992 PMCID: PMC6436651 DOI: 10.1096/fj.201801499rrr] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Insight into the molecular and cellular processes in blood-retinal barrier (BRB) development, including the contribution of paracellular and transcellular pathways, is still incomplete but may help to understand the inverse process of BRB loss in pathologic eye conditions. In this comprehensive observational study, we describe in detail the formation of the BRB at the molecular level in physiologic conditions, using mice from postnatal day (P)3 to P25. Our data indicate that immature blood vessels already have tight junctions at P5, before the formation of a functional BRB. Expression of the endothelial cell-specific protein plasmalemma vesicle-associated protein (PLVAP), which is known to be involved in transcellular transport and associated with BRB permeability, decreased during development and was absent when a functional barrier was formed. Moreover, we show that PLVAP deficiency causes a transient delay in retinal vascular development and changes in mRNA expression levels of endothelial permeability pathway proteins.-Van der Wijk, A.-E., Wisniewska-Kruk, J., Vogels, I. M. C., van Veen, H. A., Ip, W. F., van der Wel, N. N., van Noorden, C. J. F., Schlingemann, R. O., Klaassen, I. Expression patterns of endothelial permeability pathways in the development of the blood-retinal barrier in mice.
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Affiliation(s)
- Anne-Eva van der Wijk
- Departments of Ophthalmology and Medical Biology, Amsterdam UMC, Ocular Angiogenesis Group, Amsterdam Cardiovascular Sciences, Cancer Center Amsterdam, University of Amsterdam, Amsterdam, The Netherlands
| | - Joanna Wisniewska-Kruk
- Departments of Ophthalmology and Medical Biology, Amsterdam UMC, Ocular Angiogenesis Group, Amsterdam Cardiovascular Sciences, Cancer Center Amsterdam, University of Amsterdam, Amsterdam, The Netherlands
| | - Ilse M C Vogels
- Departments of Ophthalmology and Medical Biology, Amsterdam UMC, Ocular Angiogenesis Group, Amsterdam Cardiovascular Sciences, Cancer Center Amsterdam, University of Amsterdam, Amsterdam, The Netherlands
| | - Henk A van Veen
- Department of Medical Biology, Amsterdam UMC, Electron Microscopy Center Amsterdam, University of Amsterdam, Amsterdam, The Netherlands
| | - Wing Fung Ip
- Departments of Ophthalmology and Medical Biology, Amsterdam UMC, Ocular Angiogenesis Group, Amsterdam Cardiovascular Sciences, Cancer Center Amsterdam, University of Amsterdam, Amsterdam, The Netherlands
| | - Nicole N van der Wel
- Department of Medical Biology, Amsterdam UMC, Electron Microscopy Center Amsterdam, University of Amsterdam, Amsterdam, The Netherlands
| | - Cornelis J F van Noorden
- Departments of Ophthalmology and Medical Biology, Amsterdam UMC, Ocular Angiogenesis Group, Amsterdam Cardiovascular Sciences, Cancer Center Amsterdam, University of Amsterdam, Amsterdam, The Netherlands.,Department of Medical Biology, Amsterdam UMC, Cellular Imaging Core Facility, University of Amsterdam, Amsterdam, The Netherlands.,Department of Genetic Toxicology and Tumor Biology, National Institute of Biology, Ljubljana, Slovenia; and
| | - Reinier O Schlingemann
- Departments of Ophthalmology and Medical Biology, Amsterdam UMC, Ocular Angiogenesis Group, Amsterdam Cardiovascular Sciences, Cancer Center Amsterdam, University of Amsterdam, Amsterdam, The Netherlands.,Department of Ophthalmology, Jules Gonin Eye Hospital, University of Lausanne, Lausanne, Switzerland
| | - Ingeborg Klaassen
- Departments of Ophthalmology and Medical Biology, Amsterdam UMC, Ocular Angiogenesis Group, Amsterdam Cardiovascular Sciences, Cancer Center Amsterdam, University of Amsterdam, Amsterdam, The Netherlands
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9
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Bosma EK, van Noorden CJF, Schlingemann RO, Klaassen I. The role of plasmalemma vesicle-associated protein in pathological breakdown of blood-brain and blood-retinal barriers: potential novel therapeutic target for cerebral edema and diabetic macular edema. Fluids Barriers CNS 2018; 15:24. [PMID: 30231925 PMCID: PMC6146740 DOI: 10.1186/s12987-018-0109-2] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 08/10/2018] [Indexed: 12/14/2022] Open
Abstract
Breakdown of the blood–brain barrier (BBB) or inner blood–retinal barrier (BRB), induced by pathologically elevated levels of vascular endothelial growth factor (VEGF) or other mediators, can lead to vasogenic edema and significant clinical problems such as neuronal morbidity and mortality, or vision loss. Restoration of the barrier function with corticosteroids in the brain, or by blocking VEGF in the eye are currently the predominant treatment options for brain edema and diabetic macular edema, respectively. However, corticosteroids have side effects, and VEGF has important neuroprotective, vascular protective and wound healing functions, implying that long-term anti-VEGF therapy may also induce adverse effects. We postulate that targeting downstream effector proteins of VEGF and other mediators that are directly involved in the regulation of BBB and BRB integrity provide more attractive and safer treatment options for vasogenic cerebral edema and diabetic macular edema. The endothelial cell-specific protein plasmalemma vesicle-associated protein (PLVAP), a protein associated with trans-endothelial transport, emerges as candidate for this approach. PLVAP is expressed in a subset of endothelial cells throughout the body where it forms the diaphragms of caveolae, fenestrae and trans-endothelial channels. However, PLVAP expression in brain and eye barrier endothelia only occurs in pathological conditions associated with a compromised barrier function such as cancer, ischemic stroke and diabetic retinopathy. Here, we discuss the current understanding of PLVAP as a structural component of endothelial cells and regulator of vascular permeability in health and central nervous system disease. Besides providing a perspective on PLVAP identification, structure and function, and the regulatory processes involved, we also explore its potential as a novel therapeutic target for vasogenic cerebral edema and retinal macular edema.
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Affiliation(s)
- Esmeralda K Bosma
- Ocular Angiogenesis Group, Departments of Ophthalmology and Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, Amsterdam, The Netherlands
| | - Cornelis J F van Noorden
- Ocular Angiogenesis Group, Departments of Ophthalmology and Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, Amsterdam, The Netherlands.,Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Ljubljana, Slovenia
| | - Reinier O Schlingemann
- Ocular Angiogenesis Group, Departments of Ophthalmology and Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, Amsterdam, The Netherlands.,Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
| | - Ingeborg Klaassen
- Ocular Angiogenesis Group, Departments of Ophthalmology and Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, Amsterdam, The Netherlands. .,Ocular Angiogenesis Group, Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Meibergdreef 15, Room L3-154, 1105 AZ, Amsterdam, The Netherlands.
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10
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Díaz-Coránguez M, Ramos C, Antonetti DA. The inner blood-retinal barrier: Cellular basis and development. Vision Res 2017; 139:123-137. [PMID: 28619516 DOI: 10.1016/j.visres.2017.05.009] [Citation(s) in RCA: 154] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 05/26/2017] [Accepted: 05/30/2017] [Indexed: 01/01/2023]
Abstract
The blood-retinal barrier (BRB) regulates transport across retinal capillaries maintaining proper neural homeostasis and protecting the neural tissue from potential blood borne toxicity. Loss of the BRB contributes to the pathophysiology of a number of blinding retinal diseases including diabetic retinopathy. In this review, we address the basis of the BRB, including the molecular mechanisms that regulate flux across the retinal vascular bed. The routes of transcellular and paracellular flux are described as well as alterations in these pathways in response to permeabilizing agents in diabetes. Finally, we provide information on exciting new studies that help to elucidate the process of BRB development or barriergenesis and how understanding this process may lead to new opportunities for barrier restoration in diabetic retinopathy.
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Affiliation(s)
- Mónica Díaz-Coránguez
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, MI, United States
| | - Carla Ramos
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, MI, United States
| | - David A Antonetti
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, MI, United States.
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Gu X, Reagan AM, McClellan ME, Elliott MH. Caveolins and caveolae in ocular physiology and pathophysiology. Prog Retin Eye Res 2016; 56:84-106. [PMID: 27664379 DOI: 10.1016/j.preteyeres.2016.09.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 09/15/2016] [Accepted: 09/20/2016] [Indexed: 12/14/2022]
Abstract
Caveolae are specialized, invaginated plasma membrane domains that are defined morphologically and by the expression of signature proteins called, caveolins. Caveolae and caveolins are abundant in a variety of cell types including vascular endothelium, glia, and fibroblasts where they play critical roles in transcellular transport, endocytosis, mechanotransduction, cell proliferation, membrane lipid homeostasis, and signal transduction. Given these critical cellular functions, it is surprising that ablation of the caveolae organelle does not result in lethality suggesting instead that caveolae and caveolins play modulatory roles in cellular homeostasis. Caveolar components are also expressed in ocular cell types including retinal vascular cells, Müller glia, retinal pigment epithelium (RPE), conventional aqueous humor outflow cells, the corneal epithelium and endothelium, and the lens epithelium. In the eye, studies of caveolae and other membrane microdomains (i.e., "lipid rafts") have lagged behind what is a substantial body of literature outside vision science. However, interest in caveolae and their molecular components has increased with accumulating evidence of important roles in vision-related functions such as blood-retinal barrier homeostasis, ocular inflammatory signaling, pathogen entry at the ocular surface, and aqueous humor drainage. The recent association of CAV1/2 gene loci with primary open angle glaucoma and intraocular pressure has further enhanced the need to better understand caveolar functions in the context of ocular physiology and disease. Herein, we provide the first comprehensive review of literature on caveolae, caveolins, and other membrane domains in the context of visual system function. This review highlights the importance of caveolae domains and their components in ocular physiology and pathophysiology and emphasizes the need to better understand these important modulators of cellular function.
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Affiliation(s)
- Xiaowu Gu
- Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Alaina M Reagan
- Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Mark E McClellan
- Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Michael H Elliott
- Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
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Plasmalemma Vesicle–Associated Protein Has a Key Role in Blood-Retinal Barrier Loss. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 186:1044-54. [DOI: 10.1016/j.ajpath.2015.11.019] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 10/20/2015] [Accepted: 11/19/2015] [Indexed: 12/15/2022]
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Elkadri A, Thoeni C, Deharvengt SJ, Murchie R, Guo C, Stavropoulos JD, Marshall CR, Wales P, Bandsma RH, Cutz E, Roifman CM, Chitayat D, Avitzur Y, Stan RV, Muise AM. Mutations in Plasmalemma Vesicle Associated Protein Result in Sieving Protein-Losing Enteropathy Characterized by Hypoproteinemia, Hypoalbuminemia, and Hypertriglyceridemia. Cell Mol Gastroenterol Hepatol 2015; 1. [PMID: 26207260 PMCID: PMC4507283 DOI: 10.1016/j.jcmgh.2015.05.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS METHODS Severe intestinal diseases observed in very young children are often the result of monogenic defects. We used whole exome sequencing (WES) to examine the genetic cause in a patient with a distinct severe form of protein losing enteropathy (PLE) characterized by hypoproteinemia, hypoalbuminemia, and hypertriglyceridemia. METHODS WES was performed at the Centre for Applied Genomics, Hospital for Sick Children, Toronto, Canada. Exome library preparation was performed using the Ion Torrent AmpliSeq RDY Exome Kit. Functional studies were carried out based on the identified mutation. RESULTS Using whole exome sequencing we identified a homozygous nonsense mutation (1072C>T; p.Arg358*) in the PLVAP (plasmalemma vesicle associated protein) gene in an infant from consanguineous parents who died at five months of age of severe protein losing enteropathy. Functional studies determined that the mutated PLVAP mRNA and protein were not expressed in the patient biopsy tissues, presumably secondary to nonsense-mediated mRNA decay. Pathological analysis showed that the loss of PLVAP resulted in disruption of endothelial fenestrated diaphragms. CONCLUSIONS PLVAP p.Arg358* mutation resulted in loss of PLVAP expression with subsequent deletion of the diaphragms of endothelial fenestrae leading to plasma protein extravasation, protein-losing enteropathy and ultimately death.
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Affiliation(s)
- Abdul Elkadri
- SickKids Inflammatory Bowel Disease Center and Cell Biology Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada,Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, University of Toronto, Hospital for Sick Children, Toronto, Ontario, Canada,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Cornelia Thoeni
- SickKids Inflammatory Bowel Disease Center and Cell Biology Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada,Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, University of Toronto, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Sophie J. Deharvengt
- Department of Pathology, Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire
| | - Ryan Murchie
- SickKids Inflammatory Bowel Disease Center and Cell Biology Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada,Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, University of Toronto, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Conghui Guo
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, University of Toronto, Hospital for Sick Children, Toronto, Ontario, Canada
| | - James D. Stavropoulos
- Genome Diagnostics, Department of Paediatric Laboratory Medicine, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Christian R. Marshall
- Genome Diagnostics, Department of Paediatric Laboratory Medicine, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Paul Wales
- Group for Improvement of Intestinal Function and Treatment (GIFT), Hospital for Sick Children, Toronto, Ontario, Canada
| | - Robert H.J. Bandsma
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, University of Toronto, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Ernest Cutz
- Division of Pathology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Chaim M. Roifman
- Division of Immunology, Department of Pediatrics, University of Toronto, Hospital for Sick Children, Toronto, Ontario, Canada
| | - David Chitayat
- Clinical and Metabolic Genetics, Department of Pediatrics, University of Toronto, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Yaron Avitzur
- Group for Improvement of Intestinal Function and Treatment (GIFT), Hospital for Sick Children, Toronto, Ontario, Canada
| | - Radu V. Stan
- Department of Pathology, Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire
| | - Aleixo M. Muise
- SickKids Inflammatory Bowel Disease Center and Cell Biology Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada,Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, University of Toronto, Hospital for Sick Children, Toronto, Ontario, Canada,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada,Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada,Correspondence Address correspondence to: Aleixo Muise, MD, PhD, 555 University Avenue, Hospital for Sick Children, Toronto, Ontario, Canada, M5G 1X8. fax: (416) 813-6531.
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14
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Wisniewska-Kruk J, Klaassen I, Vogels IMC, Magno AL, Lai CM, Van Noorden CJF, Schlingemann RO, Rakoczy EP. Molecular analysis of blood-retinal barrier loss in the Akimba mouse, a model of advanced diabetic retinopathy. Exp Eye Res 2014; 122:123-31. [PMID: 24703908 DOI: 10.1016/j.exer.2014.03.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 03/06/2014] [Accepted: 03/17/2014] [Indexed: 12/31/2022]
Abstract
The molecular mechanisms of vascular leakage in diabetic macular edema and proliferative retinopathy are poorly understood, mainly due to the lack of reliable in vivo models. The Akimba (Ins2(Akita)VEGF(+/-)) mouse model combines retinal neovascularization with hyperglycemia, and in contrast to other models, displays the majority of signs of advanced clinical diabetic retinopathy (DR). To study the molecular mechanism that underlies the breakdown of the blood-retinal barrier (BRB) in diabetic macular edema and proliferative diabetic retinopathy, we investigated the retinal vasculature of Akimba and its parental mice Kimba (trVEGF029) and Akita (Ins2(Akita)). Quantitative PCR, immunohistochemistry and fluorescein angiography were used to characterize the retinal vasculature with special reference to the inner BRB. Correlations between the degree of fluorescein leakage and retinal gene expression were tested by calculating the Spearman's correlation coefficient. Fluorescein leakage demonstrating BRB loss was observed in Kimba and Akimba, but not in Akita or wild type mice. In Kimba and Akimba mice fluorescein leakage was associated with focal angiogenesis and correlated significantly with Plvap gene expression. PLVAP is an endothelial cell-specific protein that is absent in intact blood-retinal barrier, but its expression significantly increases in pathological conditions such as DR. Furthermore, in Akimba mice BRB disruption was linked to decreased expression of endothelial junction proteins, pericyte dropout and vessel loss. Despite fluorescein leakage, no alteration in BRB protein levels or pericyte coverage was detected in retinas of Kimba mice. In summary, our data not only demonstrate that hyperglycemia sensitizes retinal vasculature to the effects of VEGF, leading to more severe microvascular changes, but also confirm an important role of PLVAP in the regulation of BRB permeability.
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Affiliation(s)
- Joanna Wisniewska-Kruk
- Ocular Angiogenesis Group, Departments of Ophthalmology and Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | - Ingeborg Klaassen
- Ocular Angiogenesis Group, Departments of Ophthalmology and Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | - Ilse M C Vogels
- Ocular Angiogenesis Group, Departments of Ophthalmology and Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | - Aaron L Magno
- Department of Molecular Ophthalmology, Lions Eye Institute, Nedlands, Western Australia, Australia.
| | - Chooi-May Lai
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, Nedlands, Western Australia, Australia.
| | - Cornelis J F Van Noorden
- Ocular Angiogenesis Group, Departments of Ophthalmology and Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | - Reinier O Schlingemann
- Ocular Angiogenesis Group, Departments of Ophthalmology and Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Department of Clinical and Molecular Ophthalmogenetics, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Science (KNAW), Amsterdam, The Netherlands.
| | - Elizabeth P Rakoczy
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, Nedlands, Western Australia, Australia.
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Klaassen I, Van Noorden CJF, Schlingemann RO. Molecular basis of the inner blood-retinal barrier and its breakdown in diabetic macular edema and other pathological conditions. Prog Retin Eye Res 2013; 34:19-48. [PMID: 23416119 DOI: 10.1016/j.preteyeres.2013.02.001] [Citation(s) in RCA: 444] [Impact Index Per Article: 40.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 12/19/2012] [Accepted: 02/01/2013] [Indexed: 12/16/2022]
Abstract
Breakdown of the inner endothelial blood-retinal barrier (BRB), as occurs in diabetic retinopathy, age-related macular degeneration, retinal vein occlusions, uveitis and other chronic retinal diseases, results in vasogenic edema and neural tissue damage, causing loss of vision. The central mechanism of altered BRB function is a change in the permeability characteristics of retinal endothelial cells caused by elevated levels of growth factors, cytokines, advanced glycation end products, inflammation, hyperglycemia and loss of pericytes. Subsequently, paracellular but also transcellular transport across the retinal vascular wall increases via opening of endothelial intercellular junctions and qualitative and quantitative changes in endothelial caveolar transcellular transport, respectively. Functional changes in pericytes and astrocytes, as well as structural changes in the composition of the endothelial glycocalyx and the basal lamina around BRB endothelium further facilitate BRB leakage. As Starling's rules apply, active transcellular transport of plasma proteins by the BRB endothelial cells causing increased interstitial osmotic pressure is probably the main factor in the formation of macular edema. The understanding of the complex cellular and molecular processes involved in BRB leakage has grown rapidly in recent years. Although appropriate animal models for human conditions like diabetic macular edema are lacking, these insights have provided tools for rational design of drugs aimed at restoring the BRB as well as for design of effective transport of drugs across the BRB, to treat the chronic retinal diseases such as diabetic macular edema that affect the quality-of-life of millions of patients.
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Affiliation(s)
- Ingeborg Klaassen
- Ocular Angiogenesis Group, Department of Ophthalmology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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Wisniewska-Kruk J, Hoeben KA, Vogels IMC, Gaillard PJ, Van Noorden CJF, Schlingemann RO, Klaassen I. A novel co-culture model of the blood-retinal barrier based on primary retinal endothelial cells, pericytes and astrocytes. Exp Eye Res 2011; 96:181-90. [PMID: 22200486 DOI: 10.1016/j.exer.2011.12.003] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Revised: 11/11/2011] [Accepted: 12/03/2011] [Indexed: 12/13/2022]
Abstract
Loss of blood-retinal barrier (BRB) properties is an important feature in the pathology of diabetic macular edema (DME), but cellular mechanisms underlying BRB dysfunction are poorly understood. Therefore, we developed and characterized a novel in vitro BRB model, based on primary bovine retinal endothelial cells (BRECs). These cells were shown to maintain specific in vivo BRB properties by expressing high levels of the endothelial junction proteins occludin, claudin-5, VE-cadherin and ZO-1 at cell borders, and the specific pumps glucose transporter-1 (GLUT1) and efflux transporter P-glycoprotein (MDR1). To investigate the influence of pericytes and astrocytes on BRB maintenance in vitro, we compared five different co-culture BRB models, based on BRECs, bovine retinal pericytes (BRPCs) and rat glial cells. Co-cultures of BRECs with BRPCs and glial cells showed the highest trans-endothelial resistance (TEER) as well as decreased permeability of tracers after vascular endothelial growth factor (VEGF) stimulation, suggesting a major role for these cell types in maintaining barrier properties. To mimic the in vivo situation of DME, we stimulated BRECs with VEGF, which downregulated MDR1 and GLUT1 mRNA levels, transiently reduced expression levels of endothelial junctional proteins and altered their organization, increased the number of intercellular gaps in BRECs monolayers and influence the permeability of the model to differently-sized molecular tracers. Moreover, as has been shown in vivo, expression of plasmalemma vesicle-associated protein (PLVAP) was increased in endothelial cells in the presence of VEGF. This in vitro model is the first co-culture model of the BRB that mimicks in vivo VEGF-dependent changes occurring in DME.
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Klaassen I, Hughes JM, Vogels IM, Schalkwijk CG, Van Noorden CJ, Schlingemann RO. Altered expression of genes related to blood–retina barrier disruption in streptozotocin-induced diabetes. Exp Eye Res 2009; 89:4-15. [DOI: 10.1016/j.exer.2009.01.006] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Revised: 10/31/2008] [Accepted: 01/12/2009] [Indexed: 11/28/2022]
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Baba T, Grebe R, Hasegawa T, Bhutto I, Merges C, McLeod DS, Lutty GA. Maturation of the fetal human choriocapillaris. Invest Ophthalmol Vis Sci 2009; 50:3503-11. [PMID: 19264887 DOI: 10.1167/iovs.08-2614] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The purpose of this study was to examine the structural and functional maturation of the choriocapillaris (CC) and to determine when fenestrations form, the capillaries are invested with pericytes, and the endothelial cells (ECs) became functional. METHODS Immunohistochemistry was performed on cryopreserved sections of embryonic/fetal human eyes from 7 to 22 weeks' gestation (WG), using antibodies against PAL-E, PV-1 (fenestrations), carbonic anhydrase IV (CA IV), eNOS, and alpha-smooth muscle actin (alphaSMA) and NG2 (two pericyte markers) and the EC marker (CD31). Alkaline phosphatase (APase) enzymatic activity was demonstrated by enzyme histochemistry. Transmission electron microscopy (TEM) was performed on eyes at 11, 14, 16, and 22 WG. Adult human eyes were used as the positive control. RESULTS All EC markers were present in the CC by 7 WG. PAL-E, CA IV, and eNOS immunoreactivities and APase activity were present in the CC by 7 to 9 WG. TEM analysis demonstrated how structurally immature this vasculature was, even at 11 WG: no basement membrane, absence of pericytes, and poorly formed lumens that were filled with filopodia. The few fenestrations that were observed were often present within the luminal space in the filopodia. Contiguous fenestrations and significant PV-1 were not observed until 21 to 22 WG. alphaSMA was prominent at 22 WG, and the maturation of pericytes was confirmed by TEM. CONCLUSIONS It appears that ECs and their precursors express enzymes present in adult CC well before they are structurally mature. Although ECs make tight junctions early in development, contiguous fenestrations and mature pericytes occur much later in development.
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Affiliation(s)
- Takayuki Baba
- Wilmer Ophthalmological Institute, Johns Hopkins Hospital, Baltimore, Maryland 21287-9115, USA
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Abstract
The optic nerve head, although part of the central nervous system, lacks classical blood-brain barrier properties. The tissue of Elschnig does not totally separate the optic nerve head from fenestrated peripapillary choriocapillaries. The microvessels in the prelaminar region of the optic nerve head have less effective barriers than those in the laminar or retrolaminar regions. In glaucoma, the blood-brain barrier in the optic nerve head may even be weaker. Incomplete blood-brain barrier renders circulating molecules, such as endothelin-1 (ET-1), direct access to smooth vascular muscle cells and pericytes both in the prelaminar part of the optic nerve head and to adjacent retinal tissue. This potentially leads to some vasoconstriction as observed in the peri-papillary retinal vessel in glaucoma patients. In extreme situations, this may provoke retinal vein occlusion. The direct access of these molecules also influences the barrier function. If, simultaneously, ET-1 reduces endothelial tight-junctions and matrix-metalloproteinase (MMP)-9 degrades the basement membrane, not only macromolecules but even red blood cells may cross the blood-brain barrier and lead to what is clinically observed as optic disk hemorrhages.
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Hughes JM, Brink A, Witmer AN, Hanraads-de Riemer M, Klaassen I, Schlingemann RO. Vascular leucocyte adhesion molecules unaltered in the human retina in diabetes. Br J Ophthalmol 2004; 88:566-72. [PMID: 15031178 PMCID: PMC1772105 DOI: 10.1136/bjo.2003.021204] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND/AIMS Capillary occlusion is believed to have a critical role in the development of diabetic retinopathy (DR). The exact mechanism by which it occurs, however, remains unclear. Several in vitro and animal model studies have suggested increased adhesion of leucocytes to the endothelium via upregulated ICAM-1 on the retinal microvasculature as a possible mechanism. In this comparative immunohistochemical study the expression of ICAM-1 was compared in the retinal vasculature of 41 eyes obtained from 37 diabetic people with 19 eyes from 19 non-diabetic controls. METHODS Serial cryosections of postmortem posterior tissue from 41 diabetic eyes and 19 non-diabetic eyes were stained with the monoclonal antibodies ICAM-1 (two clones), CD31(panendothelial marker), and PAL-E (vascular leakage marker). RESULTS A similar pattern of vascular ICAM-1 staining was observed between diabetic and non-diabetic eyes. A diffuse ICAM-1 staining of the retina was also observed that was significantly more intense in the diabetic subjects (p = 0.001). CONCLUSION These results indicate that ICAM-1 is constitutively expressed on retinal and choroidal vasculature of non-diabetic, control subjects and that this level of expression is not significantly altered by the diabetic environment. Taken together, these results do not support the prevalent paradigm of increased adhesion molecule expression as a primary mechanism responsible for capillary occlusion reported in diabetic individuals.
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Affiliation(s)
- J M Hughes
- Ocular Angiogenesis Group, Department of Ophthalmology, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands
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Witmer AN, van Blijswijk BC, van Noorden CJF, Vrensen GFJM, Schlingemann RO. In vivo angiogenic phenotype of endothelial cells and pericytes induced by vascular endothelial growth factor-A. J Histochem Cytochem 2004; 52:39-52. [PMID: 14688216 DOI: 10.1177/002215540405200105] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
VEGF-A is a major angiogenesis and permeability factor. Its cellular effects, which can be used as targets in anti-angiogenesis therapy, have mainly been studied in vitro using endothelial cell cultures. The purpose of the present study was to further characterize these effects in vivo in vascular endothelial cells and pericytes, in an experimental monkey model of VEGF-A-induced iris neovascularization. Two cynomolgus monkeys (Macaca fascicularis) received four injections of 0.5 microg VEGF-A in the vitreous of one eye and PBS in the other eye. After sacrifice at day 9, eyes were enucleated and iris samples were snap-frozen for immunohistochemistry (IHC) and stained with a panel of antibodies recognizing endothelial and pericyte determinants related to angiogenesis and permeability. After VEGF-A treatment, the pre-existing iris vasculature showed increased permeability, hypertrophy, and activation, as demonstrated by increased staining of CD31, PAL-E, tPA, uPA, uPAR, Glut-1, and alphavbeta3 and alphavbeta5 integrins, VEGF receptors VEGFR-1, -2 and -3, and Tie-2 in endothelial cells, and of NG2 proteoglycan, uPA, uPAR, integrins and VEGFR-1 in pericytes. Vascular sprouts at the anterior surface of the iris were positive for the same antigens except for tPA, Glut-1, and Tie-2, which were notably absent. Moreover, in these sprouts VEGFR-2 and VEGFR-3 expression was very high in endothelial cells, whereas many pericytes were present that were positive for PDGFR-beta, VEGFR-1, and NG2 proteoglycan and negative for alpha-SMA. In conclusion, proteins that play a role in angiogenesis are upregulated in both pre-existing and newly formed iris vasculature after treatment with VEGF-A. VEGF-A induces hypertrophy and loss of barrier function in pre-existing vessels, and induces angiogenic sprouting, characterized by marked expression of VEGFR-3 and lack of expression of tPA and Tie-2 in endothelial cells, and lack of alpha-SMA in pericytes. Our in vivo study indicates a role for alpha-SMA-negative pericytes in early stages of angiogenesis. Therefore, our findings shed new light on the temporal and spatial role of several proteins in the angiogenic cascade in vivo.
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Affiliation(s)
- Antonella N Witmer
- Ocular Angiogenesis Group, Department of Ophthalmology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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Dai J, Vrensen GFJM, Schlingemann RO. Blood-brain barrier integrity is unaltered in human brain cortex with diabetes mellitus. Brain Res 2002; 954:311-6. [PMID: 12414115 DOI: 10.1016/s0006-8993(02)03294-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Diabetes-related cognitive dysfunction has been recognized for many years in humans, but the pathogenesis of this condition is poorly understood. Evidence from animal studies suggests that altered function of the blood-brain barrier (BBB) could be a potential cause contributing to this disease. This study aimed to investigate whether the permeability of the BBB is affected in the brains of persons with diabetes mellitus (DM). On postmortem prefrontal and temporal cortex of diabetic patients and controls, immunohistochemical stainings were carried out using specific antibodies against three proteins (PAL-E, IgG and albumin), which are considered as markers for the vascular permeability status of the BBB. Rare or no PAL-E staining was found in the capillaries of the prefrontal and temporal cortex parenchyma, in both DM and control materials. IgG and albumin were localized in and directly around blood vessel walls in the prefrontal and temporal cortex. No obvious differences in the staining pattern of IgG and albumin were observed between brain samples of persons with DM and controls. This study suggests that the BBB in diabetic patients is well maintained.
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Affiliation(s)
- Jiapei Dai
- Ocular Angiogenesis Group, Department of Ophthalmology, Academic Medical Center, Amsterdam, The Netherlands.
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Witmer AN, Dai J, Weich HA, Vrensen GFJM, Schlingemann RO. Expression of vascular endothelial growth factor receptors 1, 2, and 3 in quiescent endothelia. J Histochem Cytochem 2002; 50:767-77. [PMID: 12019293 DOI: 10.1177/002215540205000603] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The vascular endothelial growth factor (VEGF) family is involved in angiogenesis, and therefore VEGFs are considered as targets for anti-angiogenic therapeutic strategies against cancer. However, the physiological functions of VEGFs in quiescent tissues are unclear and may interfere with such systemic therapies. In pathological conditions, increased levels of expression of the VEGF receptors VEGFR-1, VEGFR-2, and VEGFR-3 accompany VEGF activity. In this study we investigated normal human and monkey tissues for expression patterns of these receptors. Immunohistochemical staining methods at the light and electron microscopic level were applied to normal human and monkey tissue samples, using monoclonal antibodies (MAbs) against the three VEGFRs and anti-endothelial MAbs PAL-E and anti-CD31 to identify blood and lymph vessels. In human and monkey, similar distribution patterns of the three VEGFRs were found. Co-expression of VEGFR-1, -2, and -3 was observed in microvessels adjacent to epithelia in the eye, gastrointestinal mucosa, liver, kidney, and hair follicles, which is in line with the reported preferential expression of VEGF-A in some of these epithelia. VEGFR-1, -2, and -3 expression was also observed in blood vessels and sinusoids of lymphoid tissues. Furthermore, VEGFR-1, but not VEGFR-2 and -3, was present in microvessels in brain and retina. Electron microscopy showed that VEGFR-1 expression was restricted to pericytes and VEGFR-2 to endothelial cells in normal vasculature of tonsils. These findings indicate that VEGFRs have specific distribution patterns in normal tissues, suggesting physiological functions of VEGFs that may be disturbed by systemic anti-VEGF therapy. One of these functions may be involvement of VEGF in paracrine relations between epithelia and adjacent capillaries.
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Affiliation(s)
- Antonella N Witmer
- Ocular Angiogenesis Group, Department of Ophthalmology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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Sleeman JP, Krishnan J, Kirkin V, Baumann P. Markers for the lymphatic endothelium: in search of the holy grail? Microsc Res Tech 2001; 55:61-9. [PMID: 11596151 DOI: 10.1002/jemt.1157] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The ability to discriminate reliably at the histological level between blood and lymphatic microcapillaries would greatly assist the study of a number of biological and pathological questions and may also be of clinical utility. A structure-function comparison of these types of microcapillary suggests that differences which could function as markers to allow discrimination between blood and lymphatic endothelium should exist. Indeed, to date a variety of such markers have been proposed, including basement membrane components, constituents of junctional complexes such as desmoplakin and enzymes such as 5'-nucleotidase. Additionally, a variety of cell surface molecules are thought to be differentially expressed, including PAL-E, VEGFR-3, podoplanin, and LYVE-1. Several of the lymphatic markers proposed in the literature require further characterization to demonstrate fully their lymphatic specificity and some have proven not to be reliable. The relative merits and drawbacks of each of the proposed markers is discussed.
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Affiliation(s)
- J P Sleeman
- Forschungszentrum Karlsruhe, Institute of Toxikology and Genetics, D-76021 Karlsruhe, Germany.
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Witmer AN, van den Born J, Vrensen GF, Schlingemann RO. Vascular localization of heparan sulfate proteoglycans in retinas of patients with diabetes mellitus and in VEGF-induced retinopathy using domain-specific antibodies. Curr Eye Res 2001; 22:190-7. [PMID: 11462155 DOI: 10.1076/ceyr.22.3.190.5519] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
PURPOSE The Steno hypothesis (Deckert et al. ) states that in diabetes mellitus (DM), changes in vascular heparan sulfate proteoglycan (HSPG) expression are involved in systemic endothelial dysfunction and increased capillary permeability. In diabetes-induced glomerular capillary leakage, loss of HSPG and its side chains has been documented. This study aimed to investigate whether microvascular leakage in diabetic retinopathy (DR) is also associated with altered expression of HSPG in retinal microvessels. METHODS Serial cryosections of post-mortem eyes of 22 subjects with DM and 7 controls were stained with antibodies against the core proteins of the basement membrane HSPGs agrin (Abs Bl31 and JM72) and perlecan (Ab 1948), and four antibodies against heparan sulfate side chains (HS) (Abs JM403, HepSS1, JM13, 3G10). Moreover, we investigated Cynomolgus monkey eyes injected with vascular endothelial growth factor (VEGF)-A, as a model of retinal microvas-cular leakage. The endothelial antigen PAL-E was used to detect microvascular leakage. RESULTS In the retina of all controls and DM cases, agrin and perlecan core proteins and HS as recognized by JM403 and 3G10 were expressed in the walls of microvessels. Staining for JM13 was variable between cases, but unrelated to microvascular leakage as determined by PAL-E. Staining for HepSS1 was absent in all human retinal microvessels. In monkey retinas, HSPG staining was identical to that in human retinal tissues, except for the staining for HepSS1, which was found absent in control monkey eyes but which was positive in VEGF-injected eyes. CONCLUSIONS Increased microvascular permeability in human DR is not associated with changes in expression of the HSPGs studied, whereas high amounts of VEGF may induce increased expression of the HS side chain epitope recognized by HepSS1. These results suggest that the mechanism underlying retinal leakage is different from diabetic glomerular capillary leakage.
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Affiliation(s)
- A N Witmer
- Ocular Angiogenesis Group, Department of Ophthalmology, University of Amsterdam, Academic Medical Center, Amsterdam, The Netherlands
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Schlingemann RO, Hofman P, Klooster J, Blaauwgeers HG, Van der Gaag R, Vrensen GF. Ciliary muscle capillaries have blood-tissue barrier characteristics. Exp Eye Res 1998; 66:747-54. [PMID: 9657907 DOI: 10.1006/exer.1998.0483] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
It was determined whether the capillaries in the ciliary muscle are of the blood-tissue barrier or of the permeable non-barrier type. Ciliary body and iris of normal human and animal eyes were examined by electron microscopy and by immunohistochemical staining with a panel of antibodies recognizing endothelial blood-brain barrier markers. In addition, horseradish peroxidase (HRP) tracer studies of the anterior segment were carried out in rabbits. Our results demonstrated that the capillary endothelium in human and rabbit ciliary muscle has few luminal pinocytotic vesicles and a morphological aspect suggesting the presence of tight junctions. Ciliary muscle and iris capillaries stained positive for the blood-brain barrier markers Glucose-Transporter-1 and P-Glycoprotein, while staining for the PAL-E antigen and the transferrin receptor was absent. In the rabbit ciliary muscle, vascular leakage of exogenous HRP tracer was absent. It was concluded that this functional barrier and the observed phenotype of ciliary muscle capillaries are consistent with a blood-tissue barrier function similar to that of the iris microvasculature.
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Affiliation(s)
- R O Schlingemann
- Department of Ophthalmology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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