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Kumar A, Nagasaka Y, Jayananthan V, Zidan A, Heisler-Taylor T, Ambati J, Tamiya S, Kerur N. Therapeutic targeting of telomerase ameliorates experimental choroidal neovascularization. Biochim Biophys Acta Mol Basis Dis 2024; 1870:167156. [PMID: 38582267 DOI: 10.1016/j.bbadis.2024.167156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 03/29/2024] [Accepted: 03/30/2024] [Indexed: 04/08/2024]
Abstract
Choroidal neovascularization (CNV) is the principal driver of blindness in neovascular age-related macular degeneration (nvAMD). Increased activity of telomerase, has been associated with endothelial cell proliferation, survival, migration, and invasion in the context of tumor angiogenesis. Expanding on this knowledge, we investigated the role of telomerase in the development of CNV in mouse model. We observed increased gene expression and activity of telomerase in mouse CNV. Genetic deficiency of the telomerase components, telomerase reverse transcriptase (Tert) and telomerase RNA component (Terc) suppressed laser-induced CNV in mice. Similarly, a small molecule inhibitor of TERT (BIBR 1532), and antisense oligonucleotides (ASOs) targeting Tert and Terc reduced CNV growth. Bone marrow chimera studies suggested that telomerase activity in non-bone marrow-derived cells is crucial for the development of CNV. Comparison of BIBR 1532 with VEGF neutralizing therapeutic strategy in mouse revealed a comparable level of angiosuppressive activity. However, when BIBR and anti-VEGF antibodies were administered as a combination at sub-therapeutic doses, a statistically significant suppression of CNV was observed. These findings underscore the potential benefits of combining sub-therapeutic doses of BIBR and anti-VEGF antibodies for developing newer therapeutic strategies for NV-AMD. Telomerase inhibition with BIBR 1532 suppressed induction of multiple cytokines and growth factors critical for neovascularization. In conclusion, our study identifies telomerase as a promising therapeutic target for treating neovascular disease of the eye and thus provides a proof of principle for further exploration of telomerase inhibition as a novel treatment strategy for nvAMD.
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Affiliation(s)
- Aman Kumar
- Department of Ophthalmology and Visual Sciences, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Yosuke Nagasaka
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA; Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Vinodhini Jayananthan
- Department of Ophthalmology and Visual Sciences, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Asmaa Zidan
- Department of Ophthalmology and Visual Sciences, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Tyler Heisler-Taylor
- Department of Ophthalmology and Visual Sciences, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Jayakrishna Ambati
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA; Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Shigeo Tamiya
- Department of Ophthalmology and Visual Sciences, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Nagaraj Kerur
- Department of Ophthalmology and Visual Sciences, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA; Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA; Department of Microbial Infection and Immunity, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
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Gunay BO, Esenulku CM. Corneal biomechanical assessment via ocular response analyzer following intravitreal aflibercept therapy. SPEKTRUM DER AUGENHEILKUNDE 2022. [DOI: 10.1007/s00717-022-00534-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Modulation of Oxidative Stress and Inflammation in the Aged Lacrimal Gland. THE AMERICAN JOURNAL OF PATHOLOGY 2020; 191:294-308. [PMID: 33159886 DOI: 10.1016/j.ajpath.2020.10.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/05/2020] [Accepted: 10/20/2020] [Indexed: 12/18/2022]
Abstract
Inflammation and oxidative stress accompany aging. This study investigated the interplay between oxidative stress and inflammation in the lacrimal gland. C57BL/6 mice were used at 2 to 3, 12, and 24 months of age. Nuclear factor erythroid derived-2-related factor 2 (Nrf2)-/- and corresponding wild-type mice were used at 2 to 3 and 12 to 13 months of age. A separate group of 15.5 to 17 months of age C57BL/6 mice received a diet containing an Nrf2 inducer (Oltipraz) for 8 weeks. Aged C57BL/6 lacrimal glands showed significantly greater lymphocytic infiltration, higher levels of MHC II, IFN-γ, IL-1β, TNF-α, and cathepsin S (Ctss) mRNA transcripts, and greater nitrotyrosine and 4-hydroxynonenal protein. Young Nrf2-/- mice showed an increase in IL-1β, IFN-γ, MHC II, and Ctss mRNA transcripts compared with young wild-type mice and greater age-related changes at 12 to 13 months of age. Oltipraz diet significantly decreased nitrotyrosine and 4-hydroxynonenal and decreased the expression of IL-1β and TNF-α mRNA transcripts, while decreasing the frequency of CD45+CD4+ cells in lacrimal glands and significantly increasing conjunctival goblet cell density compared with a standard diet. The findings provide novel insight into the development of chronic, low-grade inflammation and oxidative stress in age-related dry eye. New therapies targeting oxidative stress pathways will be valuable in treating age-related dry eye.
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Ang WJ, Zunaina E, Norfadzillah AJ, Raja-Norliza RO, Julieana M, Ab-Hamid SA, Mahaneem M. Evaluation of vascular endothelial growth factor levels in tears and serum among diabetic patients. PLoS One 2019; 14:e0221481. [PMID: 31437234 PMCID: PMC6705830 DOI: 10.1371/journal.pone.0221481] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 08/07/2019] [Indexed: 01/16/2023] Open
Abstract
Objective Detection of vascular endothelial growth factor (VEGF) levels in ocular tissue may perhaps provide insight into the role of VEGF in the pathogenesis and progression of diabetic retinopathy (DR). The aim of this study was to evaluate the levels of VEGF in tears and serum amongst type 2 diabetes mellitus (DM) patients. Methods A comparative cross-sectional study was conducted between August 2016 and May 2018 involving type 2 DM patients with no DR, non-proliferative DR (NPDR), and proliferative DR (PDR). Tear samples were collected using no.41 Whatman filter paper (Schirmer strips) and 5 mL blood samples were drawn by venous puncture. VEGF levels in tears and serum were measured by enzyme-linked immunosorbent assay. Results A total of 88 type 2 DM patients (no DR: 30 patients, NPDR: 28 patients, PDR: 30 patients) were included in the study. Mean tear VEGF levels were significantly higher in the NPDR and PDR groups (114.4 SD 52.5 pg/mL and 150.8 SD 49.7 pg/mL, respectively) compared to the no DR group (40.4 SD 26.5 pg/mL, p < 0.001). There was no significant difference in the mean serum VEGF levels between the three groups. There was a fair correlation between serum and tear VEGF levels (p = 0.015, r = 0.263). Conclusion VEGF levels in tears were significantly higher amongst diabetic patients with DR compared to those without DR and were significantly associated with the severity of DR. There was a fair correlation between serum and tear VEGF levels. Detection of VEGF in tears is a good non-invasive predictor test for the severity of DR. A large cohort study is needed for further evaluation.
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Affiliation(s)
- Wen Jeat Ang
- Department of Ophthalmology, School of Medical Sciences, Health Campus, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
- Department of Ophthalmology, Melaka General Hospital, Jalan Mufti Haji Khalil, Melaka, Malaysia
| | - Embong Zunaina
- Department of Ophthalmology, School of Medical Sciences, Health Campus, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
- * E-mail:
| | | | - Raja Omar Raja-Norliza
- Department of Ophthalmology, Melaka General Hospital, Jalan Mufti Haji Khalil, Melaka, Malaysia
| | - Muhammed Julieana
- Department of Ophthalmology, School of Medical Sciences, Health Campus, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
| | - Siti Azrin Ab-Hamid
- Unit Biostatistics and Research Methodology, School of Medical Sciences, Health Campus, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
| | - Mohamed Mahaneem
- Department of Physiology, School of Medical Sciences, Health Campus, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
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Benz F, Wichitnaowarat V, Lehmann M, Germano RF, Mihova D, Macas J, Adams RH, Taketo MM, Plate KH, Guérit S, Vanhollebeke B, Liebner S. Low wnt/β-catenin signaling determines leaky vessels in the subfornical organ and affects water homeostasis in mice. eLife 2019; 8:43818. [PMID: 30932814 PMCID: PMC6481993 DOI: 10.7554/elife.43818] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 03/28/2019] [Indexed: 12/17/2022] Open
Abstract
The circumventricular organs (CVOs) in the central nervous system (CNS) lack a vascular blood-brain barrier (BBB), creating communication sites for sensory or secretory neurons, involved in body homeostasis. Wnt/β-catenin signaling is essential for BBB development and maintenance in endothelial cells (ECs) in most CNS vessels. Here we show that in mouse development, as well as in adult mouse and zebrafish, CVO ECs rendered Wnt-reporter negative, suggesting low level pathway activity. Characterization of the subfornical organ (SFO) vasculature revealed heterogenous claudin-5 (Cldn5) and Plvap/Meca32 expression indicative for tight and leaky vessels, respectively. Dominant, EC-specific β-catenin transcription in mice, converted phenotypically leaky into BBB-like vessels, by augmenting Cldn5+vessels, stabilizing junctions and by reducing Plvap/Meca32+ and fenestrated vessels, resulting in decreased tracer permeability. Endothelial tightening augmented neuronal activity in the SFO of water restricted mice. Hence, regulating the SFO vessel barrier may influence neuronal function in the context of water homeostasis. Infections and diseases in the brain and spine can be very damaging and debilitating. Indeed, the central nervous system also needs a carefully controlled biochemical environment to survive. As such, all animals with a backbone have barriers and defenses to protect and preserve this key system. One of these is the blood-brain barrier, a physical barrier between the brain and the outside world. Where most blood vessels allow relatively free exchange of chemicals between the blood and surrounding cells, the blood-brain barrier controls what can move between the bloodstream and the brain. Yet, there are gaps in the blood-brain barrier, specifically within structures in the brain called the circumventricular organs. These leaky vessels allow the brain cells in these regions to monitor the blood and respond to changes, for example, by triggering sensations such as hunger, thirst or nausea. It is not clear what stops the blood-brain barrier from forming in these regions and what effect the presence of a barrier would have on the brains activity, or the health and behavior of the animal. Benz et al. have now used mice and zebrafish to examine the development and structure of the blood-brain barrier. The investigation revealed that the signals that induce the blood-brain barrier throughout the brain are absent in the circumventricular organs of both species. Next, by artificially activating a protein involved in cell-cell interactions in mice, Benz et al. created blood-brain barrier-like structures in circumventricular organs by converting the leaky vessels into tight ones. This change meant that the brain cells in these regions did not respond properly to water deprivation, which potentially may have affected the regulation of thirst in these mice. Understanding the blood-brain barrier could have a variety of impacts on how we treat diseases in the central nervous system. This includes stroke, brain tumors and Alzheimers disease. These findings could particularly help scientists to better understand conditions that affect basic needs like thirst and hunger.
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Affiliation(s)
- Fabienne Benz
- Institute of Neurology (Edinger Institute), University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Viraya Wichitnaowarat
- Institute of Neurology (Edinger Institute), University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Martin Lehmann
- Institute of Neurology (Edinger Institute), University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Raoul Fv Germano
- Laboratory of Neurovascular Signaling, Department of Molecular Biology, ULB Neuroscience Institute, Université libre de Bruxelles, Bruxelles, Belgium
| | - Diana Mihova
- Institute of Neurology (Edinger Institute), University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Jadranka Macas
- Institute of Neurology (Edinger Institute), University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Ralf H Adams
- Department of Tissue Morphogenesis, Max-Planck-Institute for Molecular Biomedicine, University of Münster, Faculty of Medicine, Münster, Germany
| | - M Mark Taketo
- Division of Experimental Therapeutics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Karl-Heinz Plate
- Institute of Neurology (Edinger Institute), University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany.,Excellence Cluster Cardio-Pulmonary systems (ECCPS), Partner site Frankfurt, Frankfurt, Germany.,German Cancer Consortium (DKTK), Partner Site Frankfurt/Mainz, Frankfurt, Germany.,German Center for Cardiovascular Research (DZHK), Partner site Frankfurt/Mainz, Frankfurt, Germany.,German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Sylvaine Guérit
- Institute of Neurology (Edinger Institute), University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Benoit Vanhollebeke
- Laboratory of Neurovascular Signaling, Department of Molecular Biology, ULB Neuroscience Institute, Université libre de Bruxelles, Bruxelles, Belgium.,Walloon Excellence in Life Sciences and Biotechnology (WELBIO), Wallonia, Belgium
| | - Stefan Liebner
- Institute of Neurology (Edinger Institute), University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany.,Excellence Cluster Cardio-Pulmonary systems (ECCPS), Partner site Frankfurt, Frankfurt, Germany.,German Cancer Consortium (DKTK), Partner Site Frankfurt/Mainz, Frankfurt, Germany
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Chan-Ling T, Gole GA, Quinn GE, Adamson SJ, Darlow BA. Pathophysiology, screening and treatment of ROP: A multi-disciplinary perspective. Prog Retin Eye Res 2017; 62:77-119. [PMID: 28958885 DOI: 10.1016/j.preteyeres.2017.09.002] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 09/18/2017] [Accepted: 09/20/2017] [Indexed: 12/24/2022]
Abstract
The population of infants at risk for retinopathy of prematurity (ROP) varies by world region; in countries with well developed neonatal intensive care services, the highest risk infants are those born at less than 28 weeks gestational age (GA) and less than 1 kg at birth, while, in regions where many aspects of neonatal intensive and ophthalmological care are not routinely available, more mature infants up to 2000 g at birth and 37 weeks GA are also at risk for severe ROP. Treatment options for both groups of patients include standard retinal laser photocoagulation or, more recently, intravitreal anti-VEGF drugs. In addition to detection and treatment of ROP, this review highlights new opportunities created by telemedicine, where screening and diagnosis of ROP in remote locations can be undertaken by non-ophthalmologists using digital fundus cameras. The ophthalmological care of the ROP infant is undertaken in the wider context of neonatal care and general wellbeing of the infant. Because of this context, this review takes a multi-disciplinary perspective with contributions from retinal vascular biologists, pediatric ophthalmologists, an epidemiologist and a neonatologist. This review highlights the latest insights regarding cellular and molecular mechanisms in the formation of the retinal vasculature in the human infant, pathogenesis of ROP, detection and treatment of severe ROP, the risks and benefits of anti-VEGF therapy, the identification of new therapies over the horizon, and the optimal neonatal care regimen for best ROP outcomes, and the benefits and pitfalls of telemedicine in the remote screening and diagnosis of ROP, all of which have the potential to improve ROP outcomes.
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Affiliation(s)
- Tailoi Chan-Ling
- Department of Anatomy, School of Medical Sciences and Bosch Institute, University of Sydney, NSW 2006, Australia.
| | - Glen A Gole
- Discipline of Paediatrics and Child Health, University of Queensland, Qld Children's Hospital, Sth Brisbane, Qld 4101, Australia.
| | - Graham E Quinn
- Division of Ophthalmology, The Children's Hospital of Philadelphia and Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Samuel J Adamson
- Department of Anatomy, School of Medical Sciences and Bosch Institute, University of Sydney, NSW 2006, Australia
| | - Brian A Darlow
- Department of Paediatrics, University of Otago, Christchurch, New Zealand.
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Retinopathy of prematurity: inflammation, choroidal degeneration, and novel promising therapeutic strategies. J Neuroinflammation 2017; 14:165. [PMID: 28830469 PMCID: PMC5567917 DOI: 10.1186/s12974-017-0943-1] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Accepted: 08/14/2017] [Indexed: 01/08/2023] Open
Abstract
Retinopathy of prematurity (ROP) is an important cause of childhood blindness globally, and the incidence is rising. The disease is characterized by initial arrested retinal vascularization followed by neovascularization and ensuing retinal detachment causing permanent visual loss. Although neovascularization can be effectively treated via retinal laser ablation, it is unknown which children are at risk of entering this vision-threatening phase of the disease. Laser ablation may itself induce visual field deficits, and there is therefore a need to identify targets for novel and less destructive treatments of ROP. Inflammation is considered a key contributor to the pathogenesis of ROP. A large proportion of preterm infants with ROP will have residual visual loss linked to loss of photoreceptor (PR) and the integrity of the retinal pigment epithelium (RPE) in the macular region. Recent studies using animal models of ROP suggest that choroidal degeneration may be associated with a loss of integrity of the outer retina, a phenomenon so far largely undescribed in ROP pathogenesis. In this review, we highlight inflammatory and neuron-derived factors related to ROP progression, as well, potential targets for new treatment strategies. We also introduce choroidal degeneration as a significant cause of residual visual loss following ROP. We propose that ROP should no longer be considered an inner retinal vasculopathy only, but also a disease of choroidal degeneration affecting both retinal pigment epithelium and photoreceptor integrity.
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Gregoritza M, Messmann V, Abstiens K, Brandl FP, Goepferich AM. Controlled Antibody Release from Degradable Thermoresponsive Hydrogels Cross-Linked by Diels–Alder Chemistry. Biomacromolecules 2017. [DOI: 10.1021/acs.biomac.7b00587] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Manuel Gregoritza
- Department of Pharmaceutical
Technology, Faculty of Chemistry and Pharmacy, University of Regensburg, 93040 Regensburg, Germany
| | - Viktoria Messmann
- Department of Pharmaceutical
Technology, Faculty of Chemistry and Pharmacy, University of Regensburg, 93040 Regensburg, Germany
| | - Kathrin Abstiens
- Department of Pharmaceutical
Technology, Faculty of Chemistry and Pharmacy, University of Regensburg, 93040 Regensburg, Germany
| | - Ferdinand P. Brandl
- Department of Pharmaceutical
Technology, Faculty of Chemistry and Pharmacy, University of Regensburg, 93040 Regensburg, Germany
| | - Achim M. Goepferich
- Department of Pharmaceutical
Technology, Faculty of Chemistry and Pharmacy, University of Regensburg, 93040 Regensburg, Germany
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9
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Reina-Torres E, Wen JC, Liu KC, Li G, Sherwood JM, Chang JYH, Challa P, Flügel-Koch CM, Stamer WD, Allingham RR, Overby DR. VEGF as a Paracrine Regulator of Conventional Outflow Facility. Invest Ophthalmol Vis Sci 2017; 58:1899-1908. [PMID: 28358962 PMCID: PMC5374885 DOI: 10.1167/iovs.16-20779] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Purpose Vascular endothelial growth factor (VEGF) regulates microvascular endothelial permeability, and the permeability of Schlemm's canal (SC) endothelium influences conventional aqueous humor outflow. We hypothesize that VEGF signaling regulates outflow facility. Methods We measured outflow facility (C) in enucleated mouse eyes perfused with VEGF-A164a, VEGF-A165b, VEGF-D, or inhibitors to VEGF receptor 2 (VEGFR-2). We monitored VEGF-A secretion from human trabecular meshwork (TM) cells by ELISA after 24 hours of static culture or cyclic stretch. We used immunofluorescence microscopy to localize VEGF-A protein within the TM of mice. Results VEGF-A164a increased C in enucleated mouse eyes. Cyclic stretch increased VEGF-A secretion by human TM cells, which corresponded to VEGF-A localization in the TM of mice. Blockade of VEGFR-2 decreased C, using either of the inhibitors SU5416 or Ki8751 or the inactive splice variant VEGF-A165b. VEGF-D increased C, which could be blocked by Ki8751. Conclusions VEGF is a paracrine regulator of conventional outflow facility that is secreted by TM cells in response to mechanical stress. VEGF affects facility via VEGFR-2 likely at the level of SC endothelium. Disruption of VEGF signaling in the TM may explain why anti-VEGF therapy is associated with decreased outflow facility and sustained ocular hypertension.
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Affiliation(s)
- Ester Reina-Torres
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Joanne C Wen
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Katy C Liu
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Guorong Li
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Joseph M Sherwood
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Jason Y H Chang
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Pratap Challa
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Cassandra M Flügel-Koch
- Department of Anatomy II, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen, Germany
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - R Rand Allingham
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, United Kingdom
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Joseph M, Trinh HM, Cholkar K, Pal D, Mitra AK. Recent perspectives on the delivery of biologics to back of the eye. Expert Opin Drug Deliv 2017; 14:631-645. [PMID: 27573097 PMCID: PMC5570518 DOI: 10.1080/17425247.2016.1227783] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
INTRODUCTION Biologics are generally macromolecules, large in size with poor stability in biological environments. Delivery of biologics to tissues at the back of the eye remains a challenge. To overcome these challenges and treat posterior ocular diseases, several novel approaches have been developed. Nanotechnology-based delivery systems, like drug encapsulation technology, macromolecule implants and gene delivery are under investigation. We provide an overview of emerging technologies for biologics delivery to back of the eye tissues. Moreover, new biologic drugs currently in clinical trials for ocular neovascular diseases have been discussed. Areas covered: Anatomy of the eye, posterior segment disease and diagnosis, barriers to biologic delivery, ocular pharmacokinetic, novel biologic delivery system Expert opinion: Anti-VEGF therapy represents a significant advance in developing biologics for the treatment of ocular neovascular diseases. Various strategies for biologic delivery to posterior ocular tissues are under development with some in early or late stages of clinical trials. Despite significant progress in the delivery of biologics, there is unmet need to develop sustained delivery of biologics with nearly zero-order release kinetics to the back of the eye tissues. In addition, elevated intraocular pressure associated with frequent intravitreal injections of macromolecules is another concern that needs to be addressed.
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Affiliation(s)
- Mary Joseph
- Division of Pharmaceutical Sciences, School of Pharmacy, 5258 Health Science Building, University of Missouri-Kansas City, 2464 Charlotte Street, Kansas City, MO, 64108 USA
| | - Hoang M. Trinh
- Division of Pharmaceutical Sciences, School of Pharmacy, 5258 Health Science Building, University of Missouri-Kansas City, 2464 Charlotte Street, Kansas City, MO, 64108 USA
| | - Kishore Cholkar
- Division of Pharmaceutical Sciences, School of Pharmacy, 5258 Health Science Building, University of Missouri-Kansas City, 2464 Charlotte Street, Kansas City, MO, 64108 USA
- RiconPharma LLC, 100 Ford Road, Suite 9, Denville, NJ, 07834 USA
| | - Dhananjay Pal
- Division of Pharmaceutical Sciences, School of Pharmacy, 5258 Health Science Building, University of Missouri-Kansas City, 2464 Charlotte Street, Kansas City, MO, 64108 USA
| | - Ashim K. Mitra
- Division of Pharmaceutical Sciences, School of Pharmacy, 5258 Health Science Building, University of Missouri-Kansas City, 2464 Charlotte Street, Kansas City, MO, 64108 USA
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11
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Acar U, Erginturk Acar D, Alpaslan Pinarli F, Demir MN, Beyazyildiz E, Ozdemir O, Gulmez Sevim D, Tiryaki M, Sobaci G. Effects of commonly used intravitreal anti-vascular endothelial growth factor drugs on mesenchymal stem cells derived from the limbus and ciliary body. Clin Exp Ophthalmol 2016; 44:587-596. [PMID: 26856706 DOI: 10.1111/ceo.12715] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 01/25/2016] [Accepted: 01/27/2016] [Indexed: 11/28/2022]
Abstract
BACKGROUND To investigate the effects of commonly used intravitreal anti-vascular endothelial growth factor (anti-VEGF) antibodies on proliferation index and viability of mesenchymal stem cells derived from ciliary body and limbus (CB-MSC and LMSC). METHODS CB-MSCs and LMSCs were isolated from newborn rats' eyes, and they were expanded in medium by the explant method. Intravitreally used anti-VEGF drugs, aflibercept, bevacizumab and ranibizumab were tested into the 16-well plates, respectively, at four different concentrations. After keeping them for 48 h, the proliferation indexes and viabilities of CB-MSCs and LMSCs were compared separately by Real-Time Cell Analyzer and Methylthiazoltetrazoli (MTT) test. RESULTS Anti-VEGFs used at 5-times and 10-times of the standard clinical dosage caused statistically significant negative effects on proliferation indexes of CB-MSCs and LMSCs at the 24th hour compared to control group. Only the anti-VEGF group that had 10-times dosage of those used clinically had a statistically significant negative effect on the viabilties of CB-MSCs and LMSCs. CONCLUSION Administrations of high doses or repeated standard doses of intravitreal anti-VEGF agents may affect the proliferation indexes and viabilities of CB-MSCs and LMSCs adversely. These novel findings deserve further in vivo investigations.
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Affiliation(s)
- Ugur Acar
- Department of Ophthalmology, Hacettepe University, Faculty of Medicine, Ankara, Turkey.
| | - Damla Erginturk Acar
- Department of Ophthalmology, Ministry of Health, Zekai Tahir Burak Women's Health Training and Research Hospital, Ankara, Turkey
| | - Ferda Alpaslan Pinarli
- Cell Research and Genetic Diagnosis Center, Dışkapı Yıldırım Beyazıt Training and Research Hospital, Ankara, Turkey
| | - Muhammed N Demir
- Department of Ophthalmology, Yıldırım Beyazıt University, Faculty of Medicine, Ankara, Turkey
| | - Emrullah Beyazyildiz
- Department of Ophthalmology, Samsun Training and Research Hospital, Samsun, Turkey
| | - Ozdemir Ozdemir
- Department of Ophthalmology, Ministry of Health, Zekai Tahir Burak Women's Health Training and Research Hospital, Ankara, Turkey
| | - Duygu Gulmez Sevim
- Department of Ophthalmology, Erciyes University, Faculty of Medicine, Kayseri, Turkey
| | - Meral Tiryaki
- Cell Research and Genetic Diagnosis Center, Dışkapı Yıldırım Beyazıt Training and Research Hospital, Ankara, Turkey
| | - Gungor Sobaci
- Department of Ophthalmology, Hacettepe University, Faculty of Medicine, Ankara, Turkey
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12
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The effects of VEGF-A-inhibitors aflibercept and ranibizumab on the ciliary body and iris of monkeys. Graefes Arch Clin Exp Ophthalmol 2016; 254:1117-25. [PMID: 27106625 DOI: 10.1007/s00417-016-3344-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 03/28/2016] [Accepted: 04/04/2016] [Indexed: 10/21/2022] Open
Abstract
PURPOSE To investigate the effects of intravitreal ranibizumab (Lucentis®) and aflibercept (Eylea®) on the ciliary body and the iris of 12 cynomolgus monkeys with regard to the fenestrations of their blood vessels. MATERIALS AND METHODS Structural changes in the ciliary body and in the iris were investigated with light, fluorescent, and transmission electron microscopy (TEM). The latter was used to specifically quantify fenestrations of the endothelium of blood vessels after treatment with aflibercept and ranibizumab. Each of the two ciliary bodies treated with aflibercept and the two treated with ranibizumab and their controls were examined after 1 and 7 days respectively. Ophthalmological investigations including funduscopy and intraocular pressure measurements were also applied. RESULTS Ophthalmological investigations did not reveal any changes within the groups. Both drugs reduced the VEGF concentration in the ciliary body pigmented epithelium. The structure of the ciliary body was not influenced, while the posterior pigmented epithelium of the iris showed vacuoles after aflibercept treatment. Ranibizumab was mainly concentrated on the surface layer of the ciliary epithelium, in the blood vessel walls and the lumen of some of the blood vessels, and in the cells of the epithelium of the ciliary body. Aflibercept was more concentrated in the stroma and not in the cells of the epithelium, but as with ranibizumab, also in the blood vessel walls and some of their lumina, and again on the surface layer of the epithelium. Both aflibercept-and ranibizumab-treated eyes showed a decreased number of fenestrations of the capillaries in the ciliary body compared to the untreated controls. On day 1 and day 7, aflibercept had fewer fenestrations than the ranibizumab samples of the same day. CONCLUSIONS Both aflibercept and ranibizumab were found to reach the blood vessel walls of the ciliary body, and effectively reduced their fenestrations. Aflibercept might eliminate VEGF to a greater extent, possibly due to a higher elimination of fenestrations in a shorter time. Moreover, the vacuoles found in the iris need further research, in order to evaluate whether they carry a possible pathological potential.
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Forest DL, Johnson LV, Clegg DO. Cellular models and therapies for age-related macular degeneration. Dis Model Mech 2016; 8:421-7. [PMID: 26035859 PMCID: PMC4415892 DOI: 10.1242/dmm.017236] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Age-related macular degeneration (AMD) is a complex neurodegenerative visual disorder that causes profound physical and psychosocial effects. Visual impairment in AMD is caused by the loss of retinal pigmented epithelium (RPE) cells and the light-sensitive photoreceptor cells that they support. There is currently no effective treatment for the most common form of this disease (dry AMD). A new approach to treating AMD involves the transplantation of RPE cells derived from either human embryonic or induced pluripotent stem cells. Multiple clinical trials are being initiated using a variety of cell therapies. Although many animal models are available for AMD research, most do not recapitulate all aspects of the disease, hampering progress. However, the use of cultured RPE cells in AMD research is well established and, indeed, some of the more recently described RPE-based models show promise for investigating the molecular mechanisms of AMD and for screening drug candidates. Here, we discuss innovative cell-culture models of AMD and emerging stem-cell-based therapies for the treatment of this vision-robbing disease. Summary: Here, we discuss the emerging cell-culture models and potential stem-cell-based therapies for AMD, a blinding disorder that affects millions of people worldwide.
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Affiliation(s)
- David L Forest
- Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106-9625, USA
| | - Lincoln V Johnson
- Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106-9625, USA
| | - Dennis O Clegg
- Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106-9625, USA
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Kirchhof S, Gregoritza M, Messmann V, Hammer N, Goepferich AM, Brandl FP. Diels–Alder hydrogels with enhanced stability: First step toward controlled release of bevacizumab. Eur J Pharm Biopharm 2015; 96:217-25. [DOI: 10.1016/j.ejpb.2015.07.024] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 07/14/2015] [Accepted: 07/29/2015] [Indexed: 12/26/2022]
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Kirchhof S, Abrami M, Messmann V, Hammer N, Goepferich AM, Grassi M, Brandl FP. Diels–Alder Hydrogels for Controlled Antibody Release: Correlation between Mesh Size and Release Rate. Mol Pharm 2015; 12:3358-68. [DOI: 10.1021/acs.molpharmaceut.5b00375] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Susanne Kirchhof
- Department
of Pharmaceutical Technology, Faculty of Chemistry and Pharmacy, University of Regensburg, 93040 Regensburg, Germany
| | - Michela Abrami
- Department
of Life Sciences, University of Trieste, Cattinara Hospital, Strada di Fiume
447, 34127 Trieste, Italy
| | - Viktoria Messmann
- Department
of Pharmaceutical Technology, Faculty of Chemistry and Pharmacy, University of Regensburg, 93040 Regensburg, Germany
| | - Nadine Hammer
- Department
of Pharmaceutical Technology, Faculty of Chemistry and Pharmacy, University of Regensburg, 93040 Regensburg, Germany
| | - Achim M. Goepferich
- Department
of Pharmaceutical Technology, Faculty of Chemistry and Pharmacy, University of Regensburg, 93040 Regensburg, Germany
| | - Mario Grassi
- Department
of Engineering and Architecture, University of Trieste, Piazzale
Europa 1, 34127 Trieste, Italy
| | - Ferdinand P. Brandl
- Department
of Pharmaceutical Technology, Faculty of Chemistry and Pharmacy, University of Regensburg, 93040 Regensburg, Germany
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Kozlowski MR. Senescent retinal pigment epithelial cells are more sensitive to vascular endothelial growth factor: implications for "wet" age-related macular degeneration. J Ocul Pharmacol Ther 2014; 31:87-92. [PMID: 25453983 DOI: 10.1089/jop.2014.0071] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
PURPOSE Senescence of the retinal pigment epithelial (RPE) cell layer has been implicated in the occurrence of age-related macular degeneration (AMD). The present study examines whether the ability of vascular endothelial growth factor (VEGF) to decrease the barrier function of RPE cells is enhanced in senescent RPE cells, which could contribute to the pathology of "wet" AMD. METHODS Low or high population doubling level (PDL) range ARPE-19 human RPE cells were cultured in 6-well plates on membrane-containing inserts. After 2 weeks, the cells were treated with either VEGF or its vehicle and their transepithelial electrical resistance (TEER) was measured. One week later, the cells were stained for senescence-associated β-galactosidase (SABG) activity. RESULTS VEGF was significantly more effective in reducing the TEER of the high PDL ARPE-19 cell layers than the low PDL layers (25% decrease vs. 6% decrease; t-test, P=0.0013). The low PDL cell layers had a modest uniform level of SABG staining. In contrast, the high PDL layers displayed darker and more mottled SABG staining indicative of the presence of senescent cells. CONCLUSIONS The present results show that the ability of VEGF to reduce the barrier function of RPE cell layers is greater in high PDL layers, which display signs of senescence, than in low PDL layers. Senescence-induced changes in the responsiveness of RPE cell layers to VEGF could contribute to the pathology of AMD. Agents that strengthen the barrier properties of RPE cells or reduce their responsiveness to VEGF could be effective in treating "wet" AMD.
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Mathis U, Ziemssen F, Schaeffel F. Effects of a human VEGF antibody (Bevacizumab) on deprivation myopia and choroidal thickness in the chicken. Exp Eye Res 2014; 127:161-9. [PMID: 25094067 DOI: 10.1016/j.exer.2014.07.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 07/02/2014] [Accepted: 07/26/2014] [Indexed: 12/11/2022]
Abstract
Vascular endothelial growth factor (VEGF) is a dimeric glycoprotein which is responsible for neovascularization and fenestrations of the choriocapillaris. In neovascular maculopathies secondary to age-related degeneration (nAMD) or pathologic myopia (PM-CNV), its inhibition by humanized antibodies is currently the most successful therapy. The choroid has an important role in maintaining retinal health and its thickness declines with age and with myopia. Since choroidal thickness depends on its perfusion rate, one would expect that anti-VEGF agents can also change choroidal thickness. We have tested the hypothesis in the chicken model, using a humanized antibody, Bevacizumab, and also studied the distribution of VEGF-A in the chicken fundal layers by immunohistochemical techniques. Even though it was raised against human VEGF, Bevacizumab had several long lasting effects in the chicken eye (1) after a single unilateral intravitreal injection of 0.5 mg, it partially suppressed the development of deprivation myopia, similarly in both eyes, (2) it completely suppressed choroidal thickening that normally occurs when eyes recover from induced myopia over a time period of about 10 days, (3) it had little effect on the choroidal thickness in eyes that had normal visual experience, (4) VEGF-A was absent in sclera, but highly expressed in the walls of choroidal blood vessels and presumed nerve fiber bundles, as well as in retinal photoreceptors and cells of the inner and outer nuclear layer. One day after the injection of Bevacizumab, the immunoreactivity against VEGF-A had largely disappeared. In conclusion, Bevacizumab is similary effective in human and chicken tissue, has similar time constants (few days), has almost symmetrical effects on myopia in both eyes even after monocular application, and fully suppresses choroidal thickening that normally occurs during recovery from deprivation myopia. The mechanisms by which Bevacizumab acts on the choroidal thickness are perhaps most interesting, both to better understand the role of the choroid in myopia development but also to clarify its potential side effects during nAMD and PM-CNV treatment in the clinics.
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Affiliation(s)
- Ute Mathis
- Section of Neurobiology of the Eye, Ophthalmic Research Institute, University of Tuebingen, Calwerstrasse 7/1, 72076 Tübingen, Germany
| | - Focke Ziemssen
- University Eye Hospital, Department of Ophthalmology, Schleichstrasse 12-16, 72076 Tuebingen, Germany
| | - Frank Schaeffel
- Section of Neurobiology of the Eye, Ophthalmic Research Institute, University of Tuebingen, Calwerstrasse 7/1, 72076 Tübingen, Germany.
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19
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Sidhu MS, Choi MY, Woo SY, Lee HK, Lee HS, Kim KJ, Jeoung SC, Choi JS, Joo CK, Park IH. Femtosecond laser-assisted selective reduction of neovascularization in rat cornea. Lasers Med Sci 2014; 29:1417-27. [PMID: 24570086 PMCID: PMC4074465 DOI: 10.1007/s10103-014-1545-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 02/04/2014] [Indexed: 11/30/2022]
Abstract
Nonlinear multiphoton absorption induced by focusing near infrared (NIR) femtosecond (fs) laser pulses into a transparent cornea allows surgery on neovascular structures with minimal collateral damage. In this report, we introduce an fs laser-based microsurgery for selective treatment of rat corneal neovascularizations (in vivo). Contiguous tissue effects are achieved by scanning a focused laser pulse below the corneal surface with a fluence range of 2.2–8.6 J/cm2. The minimal visible laser lesion (MVL) threshold determined over the corneal neovascular structures was found to be 4.3 J/cm2. Histological and optical coherence tomography examinations of the anterior segment after laser irradiations show localized degeneration of neovascular structures without any unexpected change in adjacent tissues. Furthermore, an approximately 30 % reduction in corneal neovascularizations was observed after 5 days of fs laser exposure. The femtosecond laser is thus a promising tool for minimally invasive intrastromal surgery with the aid of a significantly smaller and more deterministic photodisruptive energy threshold for the interaction between the fs laser pulse and corneal neovascular structures.
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Affiliation(s)
- Mehra S Sidhu
- Center for Medical Metrology, Division of Convergence Technology, Korea Research Institute of Standards and Science, Daejeon, 305 340, Republic of Korea
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Gu X, Fliesler SJ, Zhao YY, Stallcup WB, Cohen AW, Elliott MH. Loss of caveolin-1 causes blood-retinal barrier breakdown, venous enlargement, and mural cell alteration. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 184:541-55. [PMID: 24326256 DOI: 10.1016/j.ajpath.2013.10.022] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 09/13/2013] [Accepted: 10/28/2013] [Indexed: 12/20/2022]
Abstract
Blood-retinal barrier (BRB) breakdown and related vascular changes are implicated in several ocular diseases. The molecules and mechanisms regulating BRB integrity and pathophysiology are not fully elucidated. Caveolin-1 (Cav-1) ablation results in loss of caveolae and microvascular pathologies, but the role of Cav-1 in the retina is largely unknown. We examined BRB integrity and vasculature in Cav-1 knockout mice and found a significant increase in BRB permeability, compared with wild-type controls, with branch veins being frequent sites of breakdown. Vascular hyperpermeability occurred without apparent alteration in junctional proteins. Such hyperpermeability was not rescued by inhibiting eNOS activity. Veins of Cav-1 knockout retinas exhibited additional pathological features, including i) eNOS-independent enlargement, ii) altered expression of mural cell markers (eg, down-regulation of NG2 and up-regulation of αSMA), and iii) dramatic alterations in mural cell phenotype near the optic nerve head. We observed a significant NO-dependent increase in retinal artery diameter in Cav-1 knockout mice, suggesting that Cav-1 plays a role in autoregulation of resistance vessels in the retina. These findings implicate Cav-1 in maintaining BRB integrity in retinal vasculature and suggest a previously undefined role in the retinal venous system and associated mural cells. Our results are relevant to clinically significant retinal disorders with vascular pathologies, including diabetic retinopathy, uveoretinitis, and primary open-angle glaucoma.
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Affiliation(s)
- Xiaowu Gu
- Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Steven J Fliesler
- Research Service, Veterans Affairs Western New York Healthcare System, Buffalo, New York; Department of Ophthalmology, University at Buffalo, State University of New York, Buffalo, New York; Department of Biochemistry, University at Buffalo, State University of New York, Buffalo, New York; SUNY Eye Institute, University at Buffalo, State University of New York, Buffalo, New York
| | - You-Yang Zhao
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois; Center for Lung and Vascular Biology, University of Illinois College of Medicine, Chicago, Illinois
| | - William B Stallcup
- Tumor Microenvironment Program, Cancer Center, Sanford-Burnham Medical Research Institute, La Jolla, California
| | - Alex W Cohen
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Michael H Elliott
- Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma.
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Abstracts of the European Vitreoretinal Update 2013, the 13th Euretina Congress. September 2013. Hamburg, Germany. Ophthalmologica 2013; 230 Suppl 1:1-30. [PMID: 24081148 DOI: 10.1159/000354999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Chatterjee S, Wang Y, Duncan MK, Naik UP. Junctional adhesion molecule-A regulates vascular endothelial growth factor receptor-2 signaling-dependent mouse corneal wound healing. PLoS One 2013; 8:e63674. [PMID: 23667656 PMCID: PMC3648504 DOI: 10.1371/journal.pone.0063674] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 04/07/2013] [Indexed: 12/04/2022] Open
Abstract
Inflammation and angiogenesis are integral parts of wound healing. However, excessive and persistent wound-induced inflammation and angiogenesis in an avascular tissue such as the cornea may be associated with scarring and visual impairment. Junctional adhesion molecule A (Jam-A) is a tight junction protein that regulates leukocyte transmigration as well as fibroblast growth factor-2 (FGF-2)-induced angiogenesis. However its function in wound-induced inflammation and angiogenesis is still unknown. In this study, we report spontaneous corneal opacity in Jam-A deficient mice associated with inflammation, angiogenesis and the presence of myofibroblasts. Since wounds and/or corneal infections cause corneal opacities, we tested the role of Jam-A in wound-induced inflammation, angiogenesis and scarring by subjecting Jam-A deficient mice to full thickness corneal wounding. Analysis of these wounds demonstrated increased inflammation, angiogenesis, and increased number of myofibroblasts thereby indicating that Jam-A regulates the wound-healing response by controlling wound-induced inflammation, angiogenesis and scarring in the cornea. These effects were not due to inflammation alone since the inflammation-induced wound-healing response in Jam-A deficient mice was similar to wild type mice. In order to determine the molecular mechanism associated with the observed aberrant corneal wound healing in Jam-A deficient mice, we assessed the expression of the components of vascular endothelial growth factor A (VEGF-A)/vascular endothelial growth factor receptor- 2(VEGFR-2) signaling pathway. Interestingly, we observed increased levels of VEGF-A mRNA in Jam-A deficient eyes. We also observed nuclear localization of phosphorylated SMAD3 (pSMAD3) indicative of TGFβ pathway activation in the Jam-A deficient eyes. Furthermore the increased wound-induced corneal inflammation, angiogenesis, and scarring in Jam-A deficient mice was attenuated by treatment with DC101, an anti-vascular endothelial growth factor receptor-2 (VEGFR-2) antibody. Our results suggest that in the absence of Jam-A, the VEGF-A/VEGFR-2 pathway is upregulated, thereby augmenting wound induced corneal inflammation, angiogenesis, and myofibroblast accumulation leading to scarring.
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Affiliation(s)
- Sharmila Chatterjee
- Department of Biological Sciences, University of Delaware, Newark, Delaware, United States of America
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Neelam S, Brooks MM, Cammarata PR. Lenticular cytoprotection. Part 1: the role of hypoxia inducible factors-1α and -2α and vascular endothelial growth factor in lens epithelial cell survival in hypoxia. Mol Vis 2013; 19:1-15. [PMID: 23335846 PMCID: PMC3541047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 12/14/2012] [Indexed: 11/20/2022] Open
Abstract
PURPOSE The prosurvival signaling cascades that mediate the unique ability of human lens epithelial cells to survive in their naturally hypoxic environment are not well defined. Hypoxia induces the synthesis of the hypoxia inducible factor HIF-1α that in turn, plays a crucial role in modulating a downstream survival scheme, where vascular endothelial growth factor (VEGF) also plays a major role. To date, no published reports in the lens literature attest to the expression and functionality of HIF-2α and the role it might play in regulating VEGF expression. The aim of this study was to identify the functional expression of the hypoxia inducible factors HIF-1α and HIF-2α and establish their role in regulating VEGF expression. Furthermore, we demonstrate a link between sustained VEGF expression and the ability of the hypoxic human lens epithelial cell to thrive in low oxygen conditions and resist mitochondrial membrane permeability transition (also referred to as lenticular cytoprotection). METHODS Hypoxia inducible factor translation inhibitors were used to demonstrate the role of HIF-1α and HIF-2α and the simultaneous expression of both hypoxic inducible factors to determine their role in regulating VEGF expression. Axitinib, which inhibits lenticular cell autophosphorylation of its VEGF receptor, was employed to demonstrate a role for the VEGF-VEGFR2 receptor complex in regulating Bcl-2 expression. Specific antisera and western blot analysis were used to detect the protein levels of HIF-1α and HIF-2α, as well as the proapoptotic protein, BAX and the prosurvival protein, Bcl-2. VEGF levels were analyzed with enzyme-linked immunosorbent assay (ELISA). The potentiometric dye, 5,5',6,6'-tetrachloro1,1',3,3'-tetraethyl-benzimidazolylcarbocyanine iodide, was used to determine the effect of the inhibitors on mitochondrial membrane permeability transition. RESULTS Cultured human lens epithelial cells (HLE-B3) maintained under hypoxic condition (1% oxygen) displayed consistent accumulation of VEGF throughout the 72 h incubation period. Using hypoxia inducible factor translation inhibitors targeting HIF-1α or HIF-2α, the specific inhibition of each protein did not diminish VEGF synthesis. The combined inhibition of HIF-1α and HIF-2α expression, using a double hypoxia inducible factor translation inhibitor, markedly decreased the level of VEGF. The inhibition of VEGF synthesis was associated with a profound deficiency in the level of the prosurvival protein, Bcl-2. Axitinib also prevented the VEGF-mediated expression of Bcl-2. The loss of VEGF coupled with the decrease in intracellular Bcl-2 correlated with marked mitochondrial depolarization, an early predictor of cellular apoptosis. CONCLUSIONS Our data support a model in which the sustained synthesis of VEGF in human lens epithelial cells, maintained under hypoxic condition, is regulated by a compensatory inter-relationship between HIF-1α and HIF-2α. VEGF acts as a prosurvival factor in hypoxic lens epithelial cells by maintaining consistent expression of the prosurvival protein Bcl-2, which likely prevents the translocation of cytosolic BAX to the outer mitochondrial membrane, thus preventing the initiation of mitochondrial depolarization.
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