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Sadikan MZ, Abdul Nasir NA, Lambuk L, Mohamud R, Reshidan NH, Low E, Singar SA, Mohmad Sabere AS, Iezhitsa I, Agarwal R. Diabetic retinopathy: a comprehensive update on in vivo, in vitro and ex vivo experimental models. BMC Ophthalmol 2023; 23:421. [PMID: 37858128 PMCID: PMC10588156 DOI: 10.1186/s12886-023-03155-1] [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: 04/03/2023] [Accepted: 09/26/2023] [Indexed: 10/21/2023] Open
Abstract
Diabetic retinopathy (DR), one of the leading causes of visual impairment and blindness worldwide, is one of the major microvascular complications in diabetes mellitus (DM). Globally, DR prevalence among DM patients is 25%, and 6% have vision-threatening problems among them. With the higher incidence of DM globally, more DR cases are expected to be seen in the future. In order to comprehend the pathophysiological mechanism of DR in humans and discover potential novel substances for the treatment of DR, investigations are typically conducted using various experimental models. Among the experimental models, in vivo models have contributed significantly to understanding DR pathogenesis. There are several types of in vivo models for DR research, which include chemical-induced, surgical-induced, diet-induced, and genetic models. Similarly, for the in vitro models, there are several cell types that are utilised in DR research, such as retinal endothelial cells, Müller cells, and glial cells. With the advancement of DR research, it is essential to have a comprehensive update on the various experimental models utilised to mimic DR environment. This review provides the update on the in vitro, in vivo, and ex vivo models used in DR research, focusing on their features, advantages, and limitations.
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Affiliation(s)
- Muhammad Zulfiqah Sadikan
- Department of Pharmacology, Faculty of Medicine, Manipal University College Malaysia (MUCM), Bukit Baru, 75150, Melaka, Malaysia
| | - Nurul Alimah Abdul Nasir
- Centre for Neuroscience Research (NeuRon), Faculty of Medicine, Universiti Teknologi MARA, 47000, Sungai Buloh, Selangor, Malaysia.
| | - Lidawani Lambuk
- Department of Immunology, School of Medical Sciences, Universiti Sains Malaysia, 16150, Kubang Kerian, Kelantan, Malaysia
| | - Rohimah Mohamud
- Department of Immunology, School of Medical Sciences, Universiti Sains Malaysia, 16150, Kubang Kerian, Kelantan, Malaysia
| | - Nur Hidayah Reshidan
- School of Biology, Faculty of Applied Sciences, Universiti Teknologi MARA, 40450, Shah Alam, Selangor, Malaysia
| | - Evon Low
- Ageing Biology Centre, Newcastle University, NE1 7RU, Newcastle upon Tyne, UK
| | - Saiful Anuar Singar
- Department of Nutrition and Integrative Physiology, College of Health and Human Sciences, Florida State University, 32306, Tallahassee, FL, USA
| | - Awis Sukarni Mohmad Sabere
- Kulliyyah of Pharmacy, International Islamic University Malaysia, Jalan Sultan Ahmad Shah, Bandar Indera Mahkota, 25200, Kuantan, Pahang, Malaysia
| | - Igor Iezhitsa
- School of Medicine, International Medical University, 57000, Bukit Jalil, Kuala Lumpur, Malaysia
- Department of Pharmacology and Bioinformatics, Volgograd State Medical University, Pavshikh Bortsov sq. 1, 400131 , Volgograd, Russian Federation
| | - Renu Agarwal
- School of Medicine, International Medical University, 57000, Bukit Jalil, Kuala Lumpur, Malaysia
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Rodent Models of Diabetic Retinopathy as a Useful Research Tool to Study Neurovascular Cross-Talk. BIOLOGY 2023; 12:biology12020262. [PMID: 36829539 PMCID: PMC9952991 DOI: 10.3390/biology12020262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 02/01/2023] [Accepted: 02/03/2023] [Indexed: 02/11/2023]
Abstract
Diabetes is a group of metabolic diseases leading to dysfunction of various organs, including ocular complications such as diabetic retinopathy (DR). Nowadays, DR treatments involve invasive options and are applied at the sight-threatening stages of DR. It is important to investigate noninvasive or pharmacological methods enabling the disease to be controlled at the early stage or to prevent ocular complications. Animal models are useful in DR laboratory practice, and this review is dedicated to them. The first part describes the characteristics of the most commonly used genetic rodent models in DR research. The second part focuses on the main chemically induced models. The authors pay particular attention to the streptozotocin model. Moreover, this section is enriched with practical aspects and contains the current protocols used in research in the last three years. Both parts include suggestions on which aspect of DR can be tested using a given model and the disadvantages of each model. Although animal models show huge variability, they are still an important and irreplaceable research tool. Note that the choice of a research model should be thoroughly considered and dependent on the aspect of the disease to be analyzed.
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Shu DY, Chaudhary S, Cho KS, Lennikov A, Miller WP, Thorn DC, Yang M, McKay TB. Role of Oxidative Stress in Ocular Diseases: A Balancing Act. Metabolites 2023; 13:187. [PMID: 36837806 PMCID: PMC9960073 DOI: 10.3390/metabo13020187] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/22/2023] [Accepted: 01/24/2023] [Indexed: 01/31/2023] Open
Abstract
Redox homeostasis is a delicate balancing act of maintaining appropriate levels of antioxidant defense mechanisms and reactive oxidizing oxygen and nitrogen species. Any disruption of this balance leads to oxidative stress, which is a key pathogenic factor in several ocular diseases. In this review, we present the current evidence for oxidative stress and mitochondrial dysfunction in conditions affecting both the anterior segment (e.g., dry eye disease, keratoconus, cataract) and posterior segment (age-related macular degeneration, proliferative vitreoretinopathy, diabetic retinopathy, glaucoma) of the human eye. We posit that further development of therapeutic interventions to promote pro-regenerative responses and maintenance of the redox balance may delay or prevent the progression of these major ocular pathologies. Continued efforts in this field will not only yield a better understanding of the molecular mechanisms underlying the pathogenesis of ocular diseases but also enable the identification of novel druggable redox targets and antioxidant therapies.
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Affiliation(s)
- Daisy Y. Shu
- Department of Ophthalmology, Schepens Eye Research Institute of Mass Eye and Ear, Harvard Medical School, Boston, MA 02114, USA
| | - Suman Chaudhary
- Department of Ophthalmology, Schepens Eye Research Institute of Mass Eye and Ear, Harvard Medical School, Boston, MA 02114, USA
| | - Kin-Sang Cho
- Department of Ophthalmology, Schepens Eye Research Institute of Mass Eye and Ear, Harvard Medical School, Boston, MA 02114, USA
| | - Anton Lennikov
- Department of Ophthalmology, Schepens Eye Research Institute of Mass Eye and Ear, Harvard Medical School, Boston, MA 02114, USA
| | - William P. Miller
- Department of Ophthalmology, Schepens Eye Research Institute of Mass Eye and Ear, Harvard Medical School, Boston, MA 02114, USA
| | - David C. Thorn
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Menglu Yang
- Department of Ophthalmology, Schepens Eye Research Institute of Mass Eye and Ear, Harvard Medical School, Boston, MA 02114, USA
| | - Tina B. McKay
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
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4
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Santos FM, Mesquita J, Castro-de-Sousa JP, Ciordia S, Paradela A, Tomaz CT. Vitreous Humor Proteome: Targeting Oxidative Stress, Inflammation, and Neurodegeneration in Vitreoretinal Diseases. Antioxidants (Basel) 2022; 11:antiox11030505. [PMID: 35326156 PMCID: PMC8944522 DOI: 10.3390/antiox11030505] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 03/03/2022] [Accepted: 03/04/2022] [Indexed: 12/12/2022] Open
Abstract
Oxidative stress is defined as an unbalance between pro-oxidants and antioxidants, as evidenced by an increase in reactive oxygen and reactive nitrogen species production over time. It is important in the pathophysiology of retinal disorders such as diabetic retinopathy, age-related macular degeneration, retinal detachment, and proliferative vitreoretinopathy, which are the focus of this article. Although the human organism’s defense mechanisms correct autoxidation caused by endogenous or exogenous factors, this may be insufficient, causing an imbalance in favor of excessive ROS production or a weakening of the endogenous antioxidant system, resulting in molecular and cellular damage. Furthermore, modern lifestyles and environmental factors contribute to increased chemical exposure and stress induction, resulting in oxidative stress. In this review, we discuss the current information about oxidative stress and the vitreous proteome with a special focus on vitreoretinal diseases. Additionally, we explore therapies using antioxidants in an attempt to rescue the body from oxidation, restore balance, and maximize healthy body function, as well as new investigational therapies that have shown significant therapeutic potential in preclinical studies and clinical trial outcomes, along with their goals and strategic approaches to combat oxidative stress.
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Affiliation(s)
- Fátima Milhano Santos
- CICS-UBI—Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, 6201-001 Covilhã, Portugal; or (J.P.C.-d.-S.)
- Unidad de Proteomica, Centro Nacional de Biotecnología, CSIC, Campus de Cantoblanco, 28049 Madrid, Spain; (S.C.); (A.P.)
- C4-UBI, Cloud Computing Competence Centre, University of Beira Interior, 6200-501 Covilhã, Portugal
- Correspondence: (F.M.S.); (C.T.T.); Tel.: +351-275-319-700 (C.T.T.)
| | - Joana Mesquita
- CICS-UBI—Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, 6201-001 Covilhã, Portugal; or (J.P.C.-d.-S.)
| | - João Paulo Castro-de-Sousa
- CICS-UBI—Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, 6201-001 Covilhã, Portugal; or (J.P.C.-d.-S.)
- Department of Ophthalmology, Centro Hospitalar de Leiria, 2410-197 Leiria, Portugal
| | - Sergio Ciordia
- Unidad de Proteomica, Centro Nacional de Biotecnología, CSIC, Campus de Cantoblanco, 28049 Madrid, Spain; (S.C.); (A.P.)
| | - Alberto Paradela
- Unidad de Proteomica, Centro Nacional de Biotecnología, CSIC, Campus de Cantoblanco, 28049 Madrid, Spain; (S.C.); (A.P.)
| | - Cândida Teixeira Tomaz
- CICS-UBI—Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, 6201-001 Covilhã, Portugal; or (J.P.C.-d.-S.)
- C4-UBI, Cloud Computing Competence Centre, University of Beira Interior, 6200-501 Covilhã, Portugal
- Chemistry Department, Faculty of Sciences, University of Beira Interior, 6201-001 Covilhã, Portugal
- Correspondence: (F.M.S.); (C.T.T.); Tel.: +351-275-319-700 (C.T.T.)
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Animal models of diabetic microvascular complications: Relevance to clinical features. Biomed Pharmacother 2021; 145:112305. [PMID: 34872802 DOI: 10.1016/j.biopha.2021.112305] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 09/29/2021] [Accepted: 10/05/2021] [Indexed: 02/06/2023] Open
Abstract
Diabetes has become more common in recent years worldwide, and this growth is projected to continue in the future. The primary concern with diabetes is developing various complications, which significantly contribute to the disease's mortality and morbidity. Over time, the condition progresses from the pre-diabetic to the diabetic stage and then to the development of complications. Years and enormous resources are required to evaluate pharmacological interventions to prevent or delay the progression of disease or complications in humans. Appropriate screening models are required to gain a better understanding of both pathogenesis and potential therapeutic agents. Different species of animals are used to evaluate the pharmacological potentials and study the pathogenesis of the disease. Animal models are essential for research because they represent most of the structural, functional, and biochemical characteristics of human diseases. An ideal screening model should mimic the pathogenesis of the disease with identifiable characteristics. A thorough understanding of animal models is required for the experimental design to select an appropriate model. Each animal model has certain advantages and limitations. The present manuscript describes the animal models and their diagnostic characteristics to evaluate microvascular diabetic complications.
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Miller WP, Sunilkumar S, Dennis MD. The stress response protein REDD1 as a causal factor for oxidative stress in diabetic retinopathy. Free Radic Biol Med 2021; 165:127-136. [PMID: 33524531 PMCID: PMC7956244 DOI: 10.1016/j.freeradbiomed.2021.01.041] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/19/2021] [Accepted: 01/21/2021] [Indexed: 12/12/2022]
Abstract
Diabetic Retinopathy (DR) is a major cause of visual dysfunction, yet much remains unknown regarding the specific molecular events that contribute to diabetes-induced retinal pathophysiology. Herein, we review the impact of oxidative stress on DR, and explore evidence that supports a key role for the stress response protein regulated in development and DNA damage (REDD1) in the development of diabetes-induced oxidative stress and functional defects in vision. It is well established that REDD1 mediates the cellular response to a number of diverse stressors through repression of the central metabolic regulator known as mechanistic target of rapamycin complex 1 (mTORC1). A growing body of evidence also supports that REDD1 acts independent of mTORC1 to promote oxidative stress by both enhancing the production of reactive oxygen species and suppressing the antioxidant response. Collectively, there is strong preclinical data to support a key role for REDD1 in the development and progression of retinal complications caused by diabetes. Furthermore, early proof-of-concept clinical trials have found a degree of success in combating ischemic retinal disease through intravitreal delivery of an siRNA targeting the REDD1 mRNA. Overall, REDD1-associated signaling represents an intriguing target for novel clinical therapies that go beyond addressing the symptoms of diabetes by targeting the underlying molecular mechanisms that contribute to DR.
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Affiliation(s)
- William P Miller
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, 17033, USA
| | - Siddharth Sunilkumar
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, 17033, USA
| | - Michael D Dennis
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, 17033, USA; Department of Ophthalmology, Penn State College of Medicine, Hershey, PA, 17033, USA.
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Choroidal and retinal structural, cellular and vascular changes in a rat model of Type 2 diabetes. Biomed Pharmacother 2020; 132:110811. [PMID: 33069967 DOI: 10.1016/j.biopha.2020.110811] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/16/2020] [Accepted: 09/25/2020] [Indexed: 12/28/2022] Open
Abstract
Increasing evidence points to inflammation as a key factor in the pathogenesis of diabetic retinopathy (DR). Choroidal changes in diabetes have been reported and several attempts were made to validate in vivo choroidal thickness (CT) as a marker of retinopathy. We aimed to study choroidal and retinal changes associated with retinopathy in an animal model of spontaneous Type 2 diabetes, Goto-Kakizaki (GK) rats. Sclerochoroidal whole mounts and cryosections were prepared from 52-week-old GK and age-matched control Wistar Han rats. CT was measured by optical coherence tomography. Microglia reactivity, pericyte and endothelial cells distribution, and immunoreactivity of vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2) were evaluated by immunofluorescence. Choroidal vessels were visualized by direct perfusion with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (Dil). Choroidal vascular density was evaluated by fluorescence microscopy. GK rats had increased CT (58.40 ± 1.15 μm versus 50.90 ± 1.58 μm, p < 0.001), reduced vascular density of the choriocapillaris (CC) (p = 0.045), increased Iba1+ cells density in the outer retina (p = 0.003) and increased VEGFR2 immunoreactivity in most retinal layers (p = 0.021 to 0.037). Choroidal microglial cells and pericytes showed polarity in their distribution, sparing the innermost choroid. This cell-free gap in the inner choroid was more pronounced in GK rats. In summary, GK rats have increased CT with decreased vascular density in the innermost choroid, increased VEGFR2 immunoreactivity in the retina and increased Iba1+ cells density in the outer retina.
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Asano T, Kunikata H, Yasuda M, Nishiguchi KM, Abe T, Nakazawa T. Ocular microcirculation changes, measured with laser speckle flowgraphy and optical coherence tomography angiography, in branch retinal vein occlusion with macular edema treated by ranibizumab. Int Ophthalmol 2020; 41:151-162. [PMID: 32894391 DOI: 10.1007/s10792-020-01562-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 08/17/2020] [Indexed: 11/28/2022]
Abstract
PURPOSE This study searched for early predictive vascular biomarkers for visual outcomes in eyes with macular edema caused by branch retinal vein occlusion (BRVOME). METHODS Twenty-four eyes of 24 subjects with BRVOME were treated with the intravitreal injection of ranibizumab (IVR) for at least 6 months. We measured mean blur rate (MBR) in the optic nerve head (ONH) and vessel density (VD) in the macula with laser speckle flowgraphy and optical coherence tomography angiography, respectively. RESULTS Six-month post-IVR best-corrected visual acuity (BCVA) was correlated positively with age, pre-IVR BCVA, 1-month post-IVR BCVA, 3-month post-IVR BCVA and pre-IVR systolic blood pressure (P < 0.001, P < 0.001, P < 0.001, P < 0.001 and P = 0.02, respectively) and negatively with pre-IVR overall MBR, 1-month post-IVR overall MBR, 6-month post-IVR overall MBR, 3-month post-IVR deep retinal capillary plexus (DCP) VD and 6-month post-IVR DCP VD (P = 0.03, P = 0.03, P = 0.02, P = 0.01 and P = 0.005, respectively). Furthermore, a multiple regression analysis showed that pre-IVR overall MBR (β = - 0.67, P = 0.009) was among independent prognostic factors predicting 6-month post-IVR BCVA. Six-month post-IVR DCP VD was also correlated with overall MBR at all time points. CONCLUSION ONH blood flow may be a pre-IVR biomarker of both visual outcomes and post-IVR deep macular microcirculation in eyes with BRVOME.
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Affiliation(s)
- Toshifumi Asano
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Hiroshi Kunikata
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan. .,Department of Retinal Disease Control, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
| | - Masayuki Yasuda
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Koji M Nishiguchi
- Department of Advanced Ophthalmic Medicine, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Toshiaki Abe
- Division of Clinical Cell Therapy, United Centers for Advanced Research and Translational Medicine, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Toru Nakazawa
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan.,Department of Retinal Disease Control, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.,Department of Advanced Ophthalmic Medicine, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.,Department of Ophthalmic Imaging and Information Analytics, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
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Wright WS, Eshaq RS, Lee M, Kaur G, Harris NR. Retinal Physiology and Circulation: Effect of Diabetes. Compr Physiol 2020; 10:933-974. [PMID: 32941691 PMCID: PMC10088460 DOI: 10.1002/cphy.c190021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
In this article, we present a discussion of diabetes and its complications, including the macrovascular and microvascular effects, with the latter of consequence to the retina. We will discuss the anatomy and physiology of the retina, including aspects of metabolism and mechanisms of oxygenation, with the latter accomplished via a combination of the retinal and choroidal blood circulations. Both of these vasculatures are altered in diabetes, with the retinal circulation intimately involved in the pathology of diabetic retinopathy. The later stages of diabetic retinopathy involve poorly controlled angiogenesis that is of great concern, but in our discussion, we will focus more on several alterations in the retinal circulation occurring earlier in the progression of disease, including reductions in blood flow and a possible redistribution of perfusion that may leave some areas of the retina ischemic and hypoxic. Finally, we include in this article a more recent area of investigation regarding the diabetic retinal vasculature, that is, the alterations to the endothelial surface layer that normally plays a vital role in maintaining physiological functions. © 2020 American Physiological Society. Compr Physiol 10:933-974, 2020.
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Affiliation(s)
- William S Wright
- Department of Biomedical Sciences, University of South Carolina School of Medicine Greenville, Greenville, South Carolina, USA
| | - Randa S Eshaq
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
| | - Minsup Lee
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
| | - Gaganpreet Kaur
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
| | - Norman R Harris
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
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Hachana S, Pouliot M, Couture R, Vaucher E. Diabetes-Induced Inflammation and Vascular Alterations in the Goto-Kakizaki Rat Retina. Curr Eye Res 2020; 45:965-974. [PMID: 31902231 DOI: 10.1080/02713683.2020.1712730] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE Diabetic retinopathy is characterized by multiple microcirculatory dysfunctions and angiogenesis resulting from hyperglycemia, oxidative stress, and inflammation. In this study, the retina and retinal pigmented epithelium of non-insulin-dependent diabetic Goto-Kakizaki (GK) rats were examined to detect microvascular alterations, gliosis, macrophage infiltration, lipid deposits, and fibrosis. Emphasis was given to the distribution of kinin B1 receptor (B1R) and vascular endothelial growth factor (VEGF), two major factors in inflammation and angiogenesis. MATERIALS AND METHODS 30-week-old male GK rats and age-matched Wistar rats were used. The retinal vascular bed was examined using ADPase staining. The level of lipid accumulation was graded using triglyceride staining with Oil red O. Macrophage and retinal microglia activation, as well as other markers, were revealed by immunohistochemistry and studied with confocal laser scanning microscopy. RESULTS Abundant lipid deposits were observed in the Bruch's membrane of GK rats. Immunohistochemistry and quantitative analysis showed significantly higher B1R, VEGF, Iba1 (microglia), CD11 (macrophages), fibronectin, and collagen I labeling in the diabetic retina. B1R immunolabeling was detected in the vascular layers of the GK retina. A strong VEGF staining within different retinal cell processes was detected and a pattern of GFAP staining suggested strong Müller cells/astrocytes reactivity. Microgliosis was apparent in the GK retina. A greater tortuosity of the retinal microvessels (an index of endothelial dysfunction) and their increased number were also observed in GK retinas. CONCLUSIONS Data suggest retinal vascular bed alterations in spontaneous type 2 diabetic retinas at 30 weeks. Lipid and collagen accumulation in the retina and choroid, in addition to retinal upregulation of VEGF and B1R, microgliosis, and Müller cell reactivity, may contribute to vascular alterations and inflammatory processes.
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Affiliation(s)
- Soumaya Hachana
- École d'optométrie, Université de Montréal , Montréal, Québec, Canada.,Département de pharmacologie et physiologie, Université de Montréal , Montréal, Québec, Canada
| | - Mylène Pouliot
- École d'optométrie, Université de Montréal , Montréal, Québec, Canada.,Département de pharmacologie et physiologie, Université de Montréal , Montréal, Québec, Canada
| | - Réjean Couture
- Département de pharmacologie et physiologie, Université de Montréal , Montréal, Québec, Canada
| | - Elvire Vaucher
- École d'optométrie, Université de Montréal , Montréal, Québec, Canada
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11
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Othman R, Vaucher E, Couture R. Bradykinin Type 1 Receptor - Inducible Nitric Oxide Synthase: A New Axis Implicated in Diabetic Retinopathy. Front Pharmacol 2019; 10:300. [PMID: 30983997 PMCID: PMC6449803 DOI: 10.3389/fphar.2019.00300] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 03/11/2019] [Indexed: 12/15/2022] Open
Abstract
Compelling evidence suggests a role for the inducible nitric oxide synthase, iNOS, and the bradykinin type 1 receptor (B1R) in diabetic retinopathy, including a possible control of the expression and activity of iNOS by B1R. In diabetic retina, both iNOS and B1R contribute to inflammation, oxidative stress, and vascular dysfunction. The present study investigated whether inhibition of iNOS has any impact on inflammatory/oxidative stress markers and on the B1R-iNOS expression, distribution, and action in a model of type I diabetes. Diabetes was induced in 6-week-old Wistar rats by streptozotocin (65 mg.kg-1, i.p.). The selective iNOS inhibitor 1400W (150 μg.10 μl-1) was administered twice a day by eye-drops during the second week of diabetes. The retinae were collected 2 weeks after diabetes induction to assess the protein and gene expression of markers by Western blot and qRT-PCR, the distribution of iNOS and B1R by fluorescence immunocytochemistry, and the vascular permeability by the Evans Blue dye technique. Diabetic retinae showed enhanced expression of iNOS, B1R, carboxypeptidase M (involved in the biosynthesis of B1R agonists), IL-1β, TNF-α, vascular endothelium growth factor A (VEGF-A) and its receptor, VEGF-R2, nitrosylated proteins and increased vascular permeability. All those changes were reversed by treatment with 1400W. Moreover, the additional increase in vascular permeability in diabetic retina induced by intravitreal injection of R-838, a B1R agonist, was also prevented by 1400W. Immunofluorescence staining highlighted strong colocalization of iNOS and B1R in several layers of the diabetic retina, which was prevented by 1400W. This study suggests a critical role for iNOS and B1R in the early stage of diabetic retinopathy. B1R and iNOS appear to partake in a mutual auto-induction and amplification loop to enhance nitrogen species formation and inflammation in diabetic retina. Hence, B1R-iNOS axis deserves closer scrutiny in targeting diabetic retinopathy.
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Affiliation(s)
- Rahmeh Othman
- School of Optometry, University of Montreal, Montreal, QC, Canada.,Department of Pharmacology and Physiology, University of Montreal, Montreal, QC, Canada
| | - Elvire Vaucher
- School of Optometry, University of Montreal, Montreal, QC, Canada
| | - Réjean Couture
- Department of Pharmacology and Physiology, University of Montreal, Montreal, QC, Canada
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Mechanisms of macular edema: Beyond the surface. Prog Retin Eye Res 2017; 63:20-68. [PMID: 29126927 DOI: 10.1016/j.preteyeres.2017.10.006] [Citation(s) in RCA: 342] [Impact Index Per Article: 48.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 10/24/2017] [Accepted: 10/31/2017] [Indexed: 02/07/2023]
Abstract
Macular edema consists of intra- or subretinal fluid accumulation in the macular region. It occurs during the course of numerous retinal disorders and can cause severe impairment of central vision. Major causes of macular edema include diabetes, branch and central retinal vein occlusion, choroidal neovascularization, posterior uveitis, postoperative inflammation and central serous chorioretinopathy. The healthy retina is maintained in a relatively dehydrated, transparent state compatible with optimal light transmission by multiple active and passive systems. Fluid accumulation results from an imbalance between processes governing fluid entry and exit, and is driven by Starling equation when inner or outer blood-retinal barriers are disrupted. The multiple and intricate mechanisms involved in retinal hydro-ionic homeostasis, their molecular and cellular basis, and how their deregulation lead to retinal edema, are addressed in this review. Analyzing the distribution of junction proteins and water channels in the human macula, several hypotheses are raised to explain why edema forms specifically in the macular region. "Pure" clinical phenotypes of macular edema, that result presumably from a single causative mechanism, are detailed. Finally, diabetic macular edema is investigated, as a complex multifactorial pathogenic example. This comprehensive review on the current understanding of macular edema and its mechanisms opens perspectives to identify new preventive and therapeutic strategies for this sight-threatening condition.
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Abstract
PURPOSE OF REVIEW Diabetic retinopathy (DR) is one of the most common complications associated with chronic hyperglycemia seen in patients with diabetes mellitus. While many facets of DR are still not fully understood, animal studies have contributed significantly to understanding the etiology and progression of human DR. This review provides a comprehensive discussion of the induced and genetic DR models in different species and the advantages and disadvantages of each model. RECENT FINDINGS Rodents are the most commonly used models, though dogs develop the most similar morphological retinal lesions as those seen in humans, and pigs and zebrafish have similar vasculature and retinal structures to humans. Nonhuman primates can also develop diabetes mellitus spontaneously or have focal lesions induced to simulate retinal neovascular disease observed in individuals with DR. DR results in vascular changes and dysfunction of the neural, glial, and pancreatic β cells. Currently, no model completely recapitulates the full pathophysiology of neuronal and vascular changes that occur at each stage of diabetic retinopathy; however, each model recapitulates many of the disease phenotypes.
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Affiliation(s)
- Ana Maria Olivares
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114 USA
| | - Kristen Althoff
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114 USA
| | - Gloria Fanghua Chen
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114 USA
| | - Siqi Wu
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114 USA
| | | | | | - Neena Haider
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114 USA
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Campos A, Campos EJ, Martins J, Ambrósio AF, Silva R. Viewing the choroid: where we stand, challenges and contradictions in diabetic retinopathy and diabetic macular oedema. Acta Ophthalmol 2017; 95:446-459. [PMID: 27545332 DOI: 10.1111/aos.13210] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 06/18/2016] [Indexed: 02/01/2023]
Abstract
Diabetic macular oedema (DMO) is the leading cause of vision loss in the working-age population. Blood-retinal barrier (BRB) dysfunction in diabetic retinopathy (DR), mainly at the level of the retinal vessels, has long been related with leakage and fluid accumulation, leading to macular oedema. However, the nourishment of the macula is provided by the choroid and a diabetic choroidopathy has been described. Therefore, there has been a growing interest in studying the role of the choroid in the pathophysiology of DR and DMO, mainly by optical coherence tomography (OCT). Nevertheless, there are conflicting results in the different studies. We summarize the results from the available studies, describe the limitations and confounding factors and discuss future procedures to avoid bias.
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Affiliation(s)
- António Campos
- Faculty of Medicine; Institute for Biomedical Imaging and Life Sciences (IBILI); University of Coimbra; Coimbra Portugal
- CNC.IBILI; University of Coimbra; Coimbra Portugal
- Department of Ophthalmology; Leiria Hospital; Leiria Portugal
| | - Elisa J. Campos
- Faculty of Medicine; Institute for Biomedical Imaging and Life Sciences (IBILI); University of Coimbra; Coimbra Portugal
- CNC.IBILI; University of Coimbra; Coimbra Portugal
| | - João Martins
- Faculty of Medicine; Institute for Biomedical Imaging and Life Sciences (IBILI); University of Coimbra; Coimbra Portugal
- CNC.IBILI; University of Coimbra; Coimbra Portugal
| | - António Francisco Ambrósio
- Faculty of Medicine; Institute for Biomedical Imaging and Life Sciences (IBILI); University of Coimbra; Coimbra Portugal
- CNC.IBILI; University of Coimbra; Coimbra Portugal
- Association for Innovation and Biomedical Research on Light and Image (AIBILI); Coimbra Portugal
| | - Rufino Silva
- Faculty of Medicine; Institute for Biomedical Imaging and Life Sciences (IBILI); University of Coimbra; Coimbra Portugal
- CNC.IBILI; University of Coimbra; Coimbra Portugal
- Association for Innovation and Biomedical Research on Light and Image (AIBILI); Coimbra Portugal
- Ophthalmology Department; Centro Hospitalar Universitário de Coimbra (CHUC); Coimbra Portugal
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Carr BC, Emigh CE, Bennett LD, Pansick AD, Birch DG, Nguyen C. TOWARDS A TREATMENT FOR DIABETIC RETINOPATHY: Intravitreal Toxicity and Preclinical Safety Evaluation of Inducible Nitric Oxide Synthase Inhibitors. Retina 2017; 37:22-31. [PMID: 27380429 DOI: 10.1097/iae.0000000000001133] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND The purpose of this study is to determine the maximum tolerated dose of a single intravitreal injection of aminoguanidine and 1400W, 2 inhibitors of inducible nitric oxide synthase, in rabbit eyes. Inhibition of inducible nitric oxide synthase has already been shown to be beneficial in various animal models of diabetic eye disease. METHODS Groups of 4 New Zealand white rabbits were injected with balanced salt solution in the right eye and a single dose of either aminoguanidine (5, 1, 0.25 mg) or 1400W (2 mg and 0.4 mg) in the left eye. Toxicity was assessed by slit-lamp and fundus examination, intraocular pressure and pachymetric measurements, and electrophysiologic and histologic analysis. RESULTS Eyes injected with high doses of aminoguanidine (5 mg) or 1400W (2 mg) demonstrated severe retinal vascular attenuation and infarction. Lower doses of intravitreal aminoguanidine (1 mg) and 1400W (0.4 mg) caused no significant toxic ocular effects in rabbit eyes. CONCLUSION If the difference in vitreal volume between rabbit eyes and human eyes is taken into account, aminoguanidine (2.7 mg) and 1400W (1 mg) would be reasonable intravitreal doses to test for safety and efficacy in early clinical trials.
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Affiliation(s)
- B Cameron Carr
- *Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas; and †Retina Foundation of the Southwest, Dallas, Texas
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Bonilha VL, Bell BA, Rayborn ME, Samuels IS, King A, Hollyfield JG, Xie C, Cai H. Absence of DJ-1 causes age-related retinal abnormalities in association with increased oxidative stress. Free Radic Biol Med 2017; 104:226-237. [PMID: 28088625 PMCID: PMC5328840 DOI: 10.1016/j.freeradbiomed.2017.01.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 01/09/2017] [Accepted: 01/10/2017] [Indexed: 01/05/2023]
Abstract
Oxidative stress alters physiological function in most biological tissues and can lead to cell death. In the retina, oxidative stress initiates a cascade of events leading to focal loss of RPE and photoreceptors, which is thought to be a major contributing factor to geographic atrophy. Despite these implications, the molecular regulation of RPE oxidative stress under normal and pathological conditions remains largely unknown. A better understanding of the mechanisms involved in regulating RPE and photoreceptors oxidative stress response is greatly needed. To this end we evaluated photoreceptor and RPE changes in mice deficient in DJ-1, a protein that is thought to be important in protecting cells from oxidative stress. Young (3 months) and aged (18 months) DJ-1 knockout (DJ-1 KO) and age-matched wild-type mice were examined. In both group of aged mice, scanning laser ophthalmoscopy (SLO) showed the presence of a few autofluorescent foci. The 18 month-old DJ-1 KO retinas were also characterized by a noticeable increase in RPE fluorescence to wild-type. Optical coherence tomography (OCT) imaging demonstrated that all retinal layers were present in the eyes of both DJ-1 KO groups. ERG comparisons showed that older DJ-1 KO mice had reduced sensitivity under dark- and light-adapted conditions compared to age-matched control. Histologically, the RPE contained prominent vacuoles in young DJ-1 KO group with the appearance of enlarged irregularly shaped RPE cells in the older group. These were also evident in OCT and in whole mount RPE/choroid preparations labeled with phalloidin. Photoreceptors in the older DJ-1 KO mice displayed decreased immunoreactivity to rhodopsin and localized reduction in cone markers compared to the wild-type control group. Lower levels of activated Nrf2 were evident in retina/RPE lysates in both young and old DJ-1 KO mouse groups compared to wild-type control levels. Conversely, higher levels of protein carbonyl derivatives and iNOS immunoreactivity were detected in retina/RPE lysates from both young and old DJ-1 KO mice. These results demonstrate that DJ-1 KO mice display progressive signs of retinal/RPE degeneration in association with higher levels of oxidative stress markers. Collectively this analysis indicates that DJ-1 plays an important role in protecting photoreceptors and RPE from oxidative damage during aging.
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Affiliation(s)
- Vera L Bonilha
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, Cleveland, OH 44195, USA; Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
| | - Brent A Bell
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Mary E Rayborn
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Ivy S Samuels
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA; Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH 44106, USA
| | - Anna King
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Joe G Hollyfield
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, Cleveland, OH 44195, USA; Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Chengsong Xie
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
| | - Huaibin Cai
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
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Kim J, Jo K, Lee IS, Kim CS, Kim JS. The Extract of Aster Koraiensis Prevents Retinal Pericyte Apoptosis in Diabetic Rats and Its Active Compound, Chlorogenic Acid Inhibits AGE Formation and AGE/RAGE Interaction. Nutrients 2016; 8:nu8090585. [PMID: 27657123 PMCID: PMC5037569 DOI: 10.3390/nu8090585] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 09/05/2016] [Accepted: 09/13/2016] [Indexed: 12/31/2022] Open
Abstract
Retinal capillary cell loss is a hallmark of early diabetic retinal changes. Advanced glycation end products (AGEs) are believed to contribute to retinal microvascular cell loss in diabetic retinopathy. In this study, the protective effects of Aster koraiensis extract (AKE) against damage to retinal vascular cells were investigated in streptozotocin (STZ)-induced diabetic rats. To examine this issue further, AGE accumulation, nuclear factor-kappaB (NF-κB) and inducible nitric oxide synthase (iNOS) were investigated using retinal trypsin digests from streptozotocin-induced diabetic rats. In the diabetic rats, TUNEL (Terminal deoxynucleotidyl transferase mediated dUTP Nick End Labeling)-positive retinal microvascular cells were markedly increased. Immunohistochemical studies revealed that AGEs were accumulated within the retinal microvascular cells, and this accumulation paralleled the activation of NF-κB and the expression of iNOS in the diabetic rats. However, AKE prevented retinal microvascular cell apoptosis through the inhibition of AGE accumulation and NF-κB activation. Moreover, to determine the active compounds of AKE, two major compounds, chlorogenic acid and 3,5-di-O-caffeoylquinic acid, were tested in an in vitro assay. Among these compounds, chlorogenic acid significantly reduced AGE formation as well as AGE/RAGE (receptor for AGEs) binding activity. These results suggest that AKE, particularly chlorogenic acid, is useful in inhibiting AGE accumulation in retinal vessels and exerts a preventive effect against the injuries of diabetic retinal vascular cells.
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Affiliation(s)
- Junghyun Kim
- Korean Medicine Convergence Research Division, Korea Institute of Oriental Medicine, Daejeon 34054, Korea.
| | - Kyuhyung Jo
- Korean Medicine Convergence Research Division, Korea Institute of Oriental Medicine, Daejeon 34054, Korea.
| | - Ik-Soo Lee
- Korean Medicine Convergence Research Division, Korea Institute of Oriental Medicine, Daejeon 34054, Korea.
| | - Chan-Sik Kim
- Korean Medicine Convergence Research Division, Korea Institute of Oriental Medicine, Daejeon 34054, Korea.
| | - Jin Sook Kim
- Korean Medicine Convergence Research Division, Korea Institute of Oriental Medicine, Daejeon 34054, Korea.
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Contribution of microglia-mediated neuroinflammation to retinal degenerative diseases. Mediators Inflamm 2015; 2015:673090. [PMID: 25873768 PMCID: PMC4385698 DOI: 10.1155/2015/673090] [Citation(s) in RCA: 159] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 12/16/2014] [Indexed: 12/27/2022] Open
Abstract
Retinal degenerative diseases are major causes of vision loss and blindness worldwide and are characterized by chronic and progressive neuronal loss. One common feature of retinal degenerative diseases and brain neurodegenerative diseases is chronic neuroinflammation. There is growing evidence that retinal microglia, as in the brain, become activated in the course of retinal degenerative diseases, having a pivotal role in the initiation and propagation of the neurodegenerative process. A better understanding of the events elicited and mediated by retinal microglia will contribute to the clarification of disease etiology and might open new avenues for potential therapeutic interventions. This review aims at giving an overview of the roles of microglia-mediated neuroinflammation in major retinal degenerative diseases like glaucoma, age-related macular degeneration, and diabetic retinopathy.
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Nitta F, Kunikata H, Aizawa N, Omodaka K, Shiga Y, Yasuda M, Nakazawa T. The effect of intravitreal bevacizumab on ocular blood flow in diabetic retinopathy and branch retinal vein occlusion as measured by laser speckle flowgraphy. Clin Ophthalmol 2014; 8:1119-27. [PMID: 24959068 PMCID: PMC4061168 DOI: 10.2147/opth.s62022] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Background This study evaluated the effect of intravitreal injection of bevacizumab (IVB) on macular edema associated with diabetic retinopathy (DME) or branch retinal vein occlusion (BRVOME) using laser speckle flowgraphy. Methods A comparative interventional study of 25 eyes from 22 patients with macular edema (DME group: 12 eyes; BRVOME group: 13 eyes) who underwent IVB. Mean blur rate (MBR) was measured in the retinal artery, retinal vein, optic nerve head (ONH), and choroid before and after IVB. Results In the BRVOME group, there was no significant change in MBR in the retinal artery, retinal vein or ONH, but choroidal MBR decreased significantly (P=0.04). In the DME group, the MBR in the retinal artery, retinal vein, ONH, and choroid decreased significantly (P=0.02, P=0.04, P<0.001, and P=0.04, respectively). In the DME group, pre-IVB MBR in the ONH was significantly correlated with post-IVB foveal thickness (R= −0.71, P=0.002). There was no such correlation in the BRVOME group in the ONH. Conclusion IVB had a suppressive effect on circulation in eyes with DME but not in those with BRVOME. This suggests that this noninvasive and objective biomarker may be a useful part of pre-IVB evaluations and decision-making in DME.
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Affiliation(s)
- Fumihiko Nitta
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Hiroshi Kunikata
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan ; Department of Retinal Disease Control, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Naoko Aizawa
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Kazuko Omodaka
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Yukihiro Shiga
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Masayuki Yasuda
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Toru Nakazawa
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan ; Department of Retinal Disease Control, Tohoku University Graduate School of Medicine, Sendai, Japan ; Department of Advanced Ophthalmic Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
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20
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Fan Y, Liu K, Wang Q, Ruan Y, Ye W, Zhang Y. Exendin-4 alleviates retinal vascular leakage by protecting the blood-retinal barrier and reducing retinal vascular permeability in diabetic Goto-Kakizaki rats. Exp Eye Res 2014; 127:104-16. [PMID: 24910901 DOI: 10.1016/j.exer.2014.05.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2013] [Revised: 05/08/2014] [Accepted: 05/11/2014] [Indexed: 12/11/2022]
Abstract
The breakdown of the inner endothelial blood-retinal barrier (BRB) and subsequent retinal vascular leakage are the main causes of vision loss due to diabetic retinopathy (DR). Exendin-4 (E4) is a long-acting agonist of the glucagon-like peptide 1 hormone receptor (GLP-1R) that is widely used in clinics and has shown a neuroprotective effect. Our previous studies demonstrated the protective effect of E4 in early experimental DR; however, the molecular and cellular mechanisms that mediate this protective effect are not fully known. The BRB plays a key role in DR. We speculated that E4 may exert its protective effects on the BRB. To test this hypothesis, E4 (0.1 μg/2 μL/eye) or vehicle were intravitreally injected into diabetic Goto-Kakizaki(GK) rats and control animals. The results revealed that E4 significantly inhibited the reductions in electroretinogram (ERG) amplitudes in the GK rats, particularly in the b-wave and oscillatory potentials (OPs). E4 upregulated retinal GLP-1R expression and downregulated the expressions of placental growth factor (PLGF) and vascular endothelial growth factor (VEGF) via the ERK and AKT/PKB pathways. Decreases in tight junction protein (i.e., claudin-5 and occludin) expression and increases in Evans blue permeation (EBP) were inhibited by E4. Similar results were also found in primary rat Müller cells in high glucose concentration cultures in vitro. We conclude that E4 may protect the BRB from diabetic insults by decreasing PLGF and ICAM-1 expression and maintaining the integrity of the BRB. Thus, E4 treatment may be an effective therapeutic approach for DR.
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Affiliation(s)
- Yichao Fan
- Department of Ophthalmology, Huashan Hospital Affiliated to Fudan University, 12 Middle Wulumuqi Road, Shanghai, China
| | - Kun Liu
- Department of Ophthalmology, First People's Hospital of Shanghai Affiliated with Shanghai Jiaotong University, Shanghai, China
| | - Qingping Wang
- Department of Ophthalmology, Huashan Hospital Affiliated to Fudan University, 12 Middle Wulumuqi Road, Shanghai, China
| | - Yuanyuan Ruan
- Key Laboratory of Glycoconjugate Research, Ministry of Public Health, Shanghai Medical College of Fudan University, Shanghai, China; Department of Biochemistry and Molecular Biology, Shanghai Medical College of Fudan University, Shanghai, China
| | - Wen Ye
- Department of Ophthalmology, Huashan Hospital Affiliated to Fudan University, 12 Middle Wulumuqi Road, Shanghai, China.
| | - Yu Zhang
- Department of Ophthalmology, Huashan Hospital Affiliated to Fudan University, 12 Middle Wulumuqi Road, Shanghai, China.
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Al-Shabrawey M, Elsherbiny M, Nussbaum J, Othman A, Megyerdi S, Tawfik A. Targeting Neovascularization in Ischemic Retinopathy: Recent Advances. EXPERT REVIEW OF OPHTHALMOLOGY 2014; 8:267-286. [PMID: 25598837 DOI: 10.1586/eop.13.17] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Pathological retinal neovascularization (RNV) is a common micro-vascular complication in several retinal diseases including retinopathy of prematurity, diabetic retinopathy, age-related macular degeneration and central vein occlusion. The current therapeutic modalities of RNV are invasive and although they may slow or halt the progression of the disease they are unlikely to restore normal acuity. Therefore, there is an urgent need to develop treatment modalities, which are less invasive and therefore associated with fewer procedural complications and systemic side effects. This review article summarizes our understanding of the pathophysiology and current treatment of RNV in ischemic retinopathies; lists potential therapeutic targets; and provides a framework for the development of future treatment modalities.
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Affiliation(s)
- Mohamed Al-Shabrawey
- Oral Biology/Anatomy, College of Dental Medicine, GeorgiaRegentsUniversity (GRU), Augusta GA, USA ; Ophthalmology and Vision Discovery Institute, Medical College of Georgia, GRU ; Anatomy, Mansoura Faculty of Medicine, Mansoura University-Egypt ; Vascular Biology Center, Medical College of Georgia, GRU
| | - Mohamed Elsherbiny
- Oral Biology/Anatomy, College of Dental Medicine, GeorgiaRegentsUniversity (GRU), Augusta GA, USA ; Ophthalmology and Vision Discovery Institute, Medical College of Georgia, GRU ; Anatomy, Mansoura Faculty of Medicine, Mansoura University-Egypt
| | - Julian Nussbaum
- Ophthalmology and Vision Discovery Institute, Medical College of Georgia, GRU
| | - Amira Othman
- Anatomy, Mansoura Faculty of Medicine, Mansoura University-Egypt
| | - Sylvia Megyerdi
- Oral Biology/Anatomy, College of Dental Medicine, GeorgiaRegentsUniversity (GRU), Augusta GA, USA
| | - Amany Tawfik
- Ophthalmology and Vision Discovery Institute, Medical College of Georgia, GRU ; Cellular Biology and Anatomy, Medical College of Georgia, GRU
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Szabadfi K, Pinter E, Reglodi D, Gabriel R. Neuropeptides, trophic factors, and other substances providing morphofunctional and metabolic protection in experimental models of diabetic retinopathy. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 311:1-121. [PMID: 24952915 DOI: 10.1016/b978-0-12-800179-0.00001-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Vision is the most important sensory modality for many species, including humans. Damage to the retina results in vision loss or even blindness. One of the most serious complications of diabetes, a disease that has seen a worldwide increase in prevalence, is diabetic retinopathy. This condition stems from consequences of pathological metabolism and develops in 75% of patients with type 1 and 50% with type 2 diabetes. The development of novel protective drugs is essential. In this review we provide a description of the disease and conclude that type 1 diabetes and type 2 diabetes lead to the same retinopathy. We evaluate existing experimental models and recent developments in finding effective compounds against this disorder. In our opinion, the best models are the long-term streptozotocin-induced diabetes and Otsuka Long-Evans Tokushima Fatty and spontaneously diabetic Torii rats, while the most promising substances are topically administered somatostatin and pigment epithelium-derived factor analogs, antivasculogenic substances, and systemic antioxidants. Future drug development should focus on these.
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Affiliation(s)
- Krisztina Szabadfi
- Department of Experimental Zoology and Neurobiology, University of Pecs, Pecs, Hungary; Janos Szentagothai Research Center, University of Pecs, Pecs, Hungary.
| | - Erika Pinter
- Janos Szentagothai Research Center, University of Pecs, Pecs, Hungary; Department of Pharmacology and Pharmacotherapy, University of Pecs, Pecs, Hungary
| | - Dora Reglodi
- Department of Anatomy, PTE MTA Lendulet-PACAP Research Team, University of Pecs, Pecs, Hungary
| | - Robert Gabriel
- Department of Experimental Zoology and Neurobiology, University of Pecs, Pecs, Hungary; Janos Szentagothai Research Center, University of Pecs, Pecs, Hungary
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An Aqueous Extract of Radix Astragali, Angelica sinensis, and Panax notoginseng Is Effective in Preventing Diabetic Retinopathy. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:578165. [PMID: 23662142 PMCID: PMC3638602 DOI: 10.1155/2013/578165] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 03/06/2013] [Accepted: 03/06/2013] [Indexed: 11/18/2022]
Abstract
Diabetic retinopathy (DR), in which inflammation has been implicated playing important roles, is one of the most common diabetes complications. Dang Gui Bu Xue Tang (DBT), an aqueous extract of Radix Astragali and Radix Angelica sinensis, is a classical prescription in Traditional Chinese Medicine for treating inflammation and ischemic diseases. Here, we investigated the effects of a modified recipe of DBT, with addition of Panax notoginseng, in treating diabetic retinopathy. An aqueous extract of Radix Astragali, Radix Angelica sinensis, and Panax notoginseng (RRP) was given to Goto-Kakizaki (GK) rats and streptozotocin-induced Sprague-Dawley (SD) rats. Leukostasis, vascular leakage, and acellular capillaries in retinal vasculature of animals were determined. Expression of retinal inflammatory biomarkers was assessed. We found that RRP reduced leukostasis, acellular capillaries, and vascular leakage compared to diabetic control rats. We also found that RRP decreased the expression of inflammatory factors including IL-1β, IL-6, TNF-α, NF-κB, MCP-1, ICAM-1, or VCAM-1 in the retinas of GK rats and reversed high glucose-induced inhibition of endothelial cell migration and proliferation in vitro. We conclude that RRP has a potent effect in preventing the pathogenesis and/or progression of DR and thus may serve as a promising nontoxic therapeutic approach of DR.
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24
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Lai AKW, Lo ACY. Animal models of diabetic retinopathy: summary and comparison. J Diabetes Res 2013; 2013:106594. [PMID: 24286086 PMCID: PMC3826427 DOI: 10.1155/2013/106594] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 09/02/2013] [Accepted: 09/02/2013] [Indexed: 12/16/2022] Open
Abstract
Diabetic retinopathy (DR) is a microvascular complication associated with chronic exposure to hyperglycemia and is a major cause of blindness worldwide. Although clinical assessment and retinal autopsy of diabetic patients provide information on the features and progression of DR, its underlying pathophysiological mechanism cannot be deduced. In order to have a better understanding of the development of DR at the molecular and cellular levels, a variety of animal models have been developed. They include pharmacological induction of hyperglycemia and spontaneous diabetic rodents as well as models of angiogenesis without diabetes (to compensate for the absence of proliferative DR symptoms). In this review, we summarize the existing protocols to induce diabetes using STZ. We also describe and compare the pathological presentations, in both morphological and functional aspects, of the currently available DR animal models. The advantages and disadvantages of using different animals, ranging from zebrafish, rodents to other higher-order mammals, are also discussed. Until now, there is no single model that displays all the clinical features of DR as seen in human. Yet, with the understanding of the pathological findings in these animal models, researchers can select the most suitable models for mechanistic studies or drug screening.
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Affiliation(s)
- Angela Ka Wai Lai
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Amy C. Y. Lo
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
- Research Center of Heart, Brain, Hormone and Healthy Aging, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
- *Amy C. Y. Lo:
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Marçal AC, Leonelli M, Fiamoncini J, Deschamps FC, Rodrigues MAM, Curi R, Carpinelli AR, Britto LRG, Carvalho CRO. Diet-induced obesity impairs AKT signalling in the retina and causes retinal degeneration. Cell Biochem Funct 2012; 31:65-74. [PMID: 22915345 DOI: 10.1002/cbf.2861] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 06/18/2012] [Accepted: 07/05/2012] [Indexed: 11/06/2022]
Abstract
Retinopathy, a common complication of diabetes, is characterized by an unbalanced production of nitric oxide (NO), a process regulated by nitric oxide synthase (NOS). We hypothesized that retinopathy might stem from changes in the insulin receptor substrate (IRS)/PI3K/AKT pathway and/or expression of NOS isoforms. Thus, we analysed the morphology and apoptosis index in retinas of obese rats in whom insulin resistance had been induced by a high-fat diet (HFD). Immunoblotting analysis revealed that the retinal tissue of HFD rats had lower levels of AKT(1) , eNOS and nNOS protein than those of samples taken from control animals. Furthermore, immunohistochemical analyses indicated higher levels of iNOS and 4-hydroxynonenal and a larger number of apoptotic nuclei in HFD rats. Finally, both the inner and outer retinal layers of HFD rats were thinner than those in their control counterparts. When considered alongside previous results, these patterns suggest two major ways in which HFD might impact animals: direct activity of ingested fatty acids and/or via insulin-resistance-induced changes in intracellular pathways. We discuss these possibilities in further detail and advocate the use of this animal model for further understanding relationships between retinopathy, metabolic syndrome and type 2 diabetes.
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Affiliation(s)
- Anderson C Marçal
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas (ICB), Universidade de São Paulo (USP), SP, Brazil.
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Protection of blood retinal barrier and systemic vasculature by insulin-like growth factor binding protein-3. PLoS One 2012; 7:e39398. [PMID: 22792172 PMCID: PMC3391198 DOI: 10.1371/journal.pone.0039398] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 05/22/2012] [Indexed: 11/19/2022] Open
Abstract
Previously, we showed that insulin growth factor (IGF)-1 binding protein-3 (IGFBP-3), independent of IGF-1, reduces pathological angiogenesis in a mouse model of the oxygen-induced retinopathy (OIR). The current study evaluates novel endothelium-dependent functions of IGFBP-3 including blood retinal barrier (BRB) integrity and vasorelaxation. To evaluate vascular barrier function, either plasmid expressing IGFBP-3 under the regulation of an endothelial-specific promoter or a control plasmid was injected into the vitreous humor of mouse pups (P1) and compared to the non-injected eyes of the same pups undergoing standard OIR protocol. Prior to sacrifice, the mice were given an injection of horseradish peroxidase (HRP). IGFBP-3 plasmid-injected eyes displayed near-normal vessel morphology and enhanced vascular barrier function. Further, in vitro IGFBP-3 protects retinal endothelial cells from VEGF-induced loss of junctional integrity by antagonizing the dissociation of the junctional complexes. To assess the vasodilatory effects of IGFBP-3, rat posterior cerebral arteries were examined in vitro. Intraluminal IGFBP-3 decreased both pressure- and serotonin-induced constrictions by stimulating nitric oxide (NO) release that were blocked by L-NAME or scavenger receptor-B1 neutralizing antibody (SRB1-Ab). Both wild-type and IGF-1-nonbinding mutant IGFBP-3 (IGFBP-3NB) stimulated eNOS activity/NO release to a similar extent in human microvascular endothelial cells (HMVECs). NO release was neither associated with an increase in intracellular calcium nor decreased by Ca2+/calmodulin-dependent protein kinase II (CamKII) blockade; however, dephosphorylation of eNOS-Thr495 was observed. Phosphatidylinositol 3-kinase (PI3K) activity and Akt-Ser473 phosphorylation were both increased by IGFBP-3 and selectively blocked by the SRB1-Ab or PI3K blocker LY294002. In conclusion, IGFBP-3 mediates protective effects on BRB integrity and mediates robust NO release to stimulate vasorelaxation via activation of SRB1. This response is IGF-1- and calcium-independent, but requires PI3K/Akt activation, suggesting that IGFBP-3 has novel protective effects on retinal and systemic vasculature and may be a therapeutic candidate for ocular complications such as diabetic retinopathy.
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Liu Y, Biarnés Costa M, Gerhardinger C. IL-1β is upregulated in the diabetic retina and retinal vessels: cell-specific effect of high glucose and IL-1β autostimulation. PLoS One 2012; 7:e36949. [PMID: 22615852 PMCID: PMC3353989 DOI: 10.1371/journal.pone.0036949] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Accepted: 04/16/2012] [Indexed: 12/12/2022] Open
Abstract
Many molecular and cellular abnormalities detected in the diabetic retina support a role for IL-1β-driven neuroinflammation in the pathogenesis of diabetic retinopathy. IL-1β is well known for its role in the induction and, through autostimulation, amplification of neuroinflammation. Upregulation of IL-1β has been consistently detected in the diabetic retina; however, the mechanisms and cellular source of IL-1β overexpression are poorly understood. The aim of this study was to investigate the effect of high glucose and IL-1β itself on IL-1β expression in microglial, macroglial (astrocytes and Müller cells) and retinal vascular endothelial cells; and to study the effect of diabetes on the expression of IL-1β in isolated retinal vessels and on the temporal pattern of IL-1β upregulation and glial reactivity in the retina of streptozotocin-diabetic rats. IL-1β was quantified by RealTime RT-PCR and ELISA, glial fibrillar acidic protein, α2-macroglobulin, and ceruloplasmin by immunoblotting. We found that high glucose induced a 3-fold increase of IL-1β expression in retinal endothelial cells but not in macroglia and microglia. IL-1β induced its own synthesis in endothelial and macroglial cells but not in microglia. In retinal endothelial cells, the high glucose-induced IL-1β overexpression was prevented by calphostin C, a protein kinase C inhibitor. The retinal vessels of diabetic rats showed increased IL-1β expression as compared to non-diabetic rats. Retinal expression of IL-1β increased early after the induction of diabetes, continued to increase with progression of the disease, and was temporally associated with upregulation of markers of glial activation. These findings point to hyperglycemia as the trigger and to the endothelium as the origin of the initial retinal upregulation of IL-1β in diabetes; and to IL-1β itself, via autostimulation in endothelial and macroglial cells, as the mechanism of sustained IL-1β overexpression. Interrupting the vicious circle triggered by IL-1β autostimulation could limit the progression of diabetic retinopathy.
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Affiliation(s)
- Yang Liu
- Schepens Eye Research Institute and the Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Montserrat Biarnés Costa
- Schepens Eye Research Institute and the Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Chiara Gerhardinger
- Schepens Eye Research Institute and the Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Coorey NJ, Shen W, Chung SH, Zhu L, Gillies MC. The role of glia in retinal vascular disease. Clin Exp Optom 2012; 95:266-81. [PMID: 22519424 DOI: 10.1111/j.1444-0938.2012.00741.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Retinal vascular diseases collectively represent a leading cause of blindness. Unsurprisingly, pathological characterisation and treatment of retinal 'vascular' diseases have primarily focused on the aetiology and consequences of vascular dysfunction. Far less research has addressed the contribution of neuronal and glial dysfunction to the disease process of retinal vascular disorders. Ample evidence now suggests that retinal vasculopathy only uncommonly occurs in isolation, usually existing in concert with neuropathy and gliopathy. Retinal glia (Müller cells, astrocytes and microglia) have been reported to exhibit morphological and functional changes in both early and advanced phases of almost every retinal vascular disease. It is anticipated that identifying the causes of glial activation and dysfunction, and their contribution to loss of vision in retinal vascular disease, will lead to a better understanding of retinal vascular diseases, which might ultimately be translated into novel clinical therapies.
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Affiliation(s)
- Nathan J Coorey
- Save Sight Institute, The University of Sydney, Sydney, Australia
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Salido EM, de Zavalía N, Schreier L, De Laurentiis A, Rettori V, Chianelli M, Keller Sarmiento MI, Arias P, Rosenstein RE. Retinal changes in an experimental model of early type 2 diabetes in rats characterized by non-fasting hyperglycemia. Exp Neurol 2012; 236:151-60. [PMID: 22554865 DOI: 10.1016/j.expneurol.2012.04.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 04/11/2012] [Accepted: 04/12/2012] [Indexed: 10/28/2022]
Abstract
Diabetic retinopathy is a leading cause of acquired blindness in young, but also in elder adults, mostly affected by type 2 diabetes mellitus (T2DM). The aim of this work was to develop an experimental model of early human T2DM in adult rats, and to analyze retinal functional, morphological, and biochemical changes arising during the early stages of the moderate metabolic derangement. For this purpose, animals were divided in four groups: adult male Wistar rats receiving: tap water and citrate buffer i.p. (group 1), tap water with 30% sucrose and citrate buffer i.p. (group 2), tap water and 25mg/kg i.p streptozotocin (STZ, group 3), or 30% sucrose and STZ (group 4). Fasting and postprandial glycemia, fructosamine and serum insulin levels were assessed. In addition, i.p. glucose and insulin tolerance tests were performed. Retinal function (electroretinogram, ERG) and morphology (optical microscopy), retinal nitric oxide synthase (NOS) activity (using (3)H-arginine), lipid peroxidation (thiobarbituric acid reactive substances, TBARS), and TNFα levels (ELISA) were evaluated. At 6 and 12 weeks of treatment, animals which received a sucrose-enriched diet and STZ showed significant differences in most metabolic tests, as compared with the other groups. At 12 weeks of treatment, a significant decrease in the ERG a- and b- wave and oscillatory potential amplitudes, and a significant increase in retinal NOS activity, TBARS, TNFα, glial fibrillary acidic protein in Müller cells, and vascular endothelial growth factor levels were observed. These results indicate that the combination of diet-induced insulin resistance and a slight secretory impairment resulting from a low-dose STZ treatment mimics some features of human T2DM at its initial stages, and provokes significant retinal alterations.
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Affiliation(s)
- Ezequiel M Salido
- Laboratory of Retinal Neurochemistry and Experimental Ophthalmology, Department of Human Biochemistry, School of Medicine, University of Buenos Aires/CEFyBO, CONICET, Buenos Aires, Argentina
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Portha B, Giroix MH, Tourrel-Cuzin C, Le-Stunff H, Movassat J. The GK rat: a prototype for the study of non-overweight type 2 diabetes. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2012; 933:125-59. [PMID: 22893405 DOI: 10.1007/978-1-62703-068-7_9] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Type 2 diabetes mellitus (T2D) arises when the endocrine pancreas fails to secrete sufficient insulin to cope with the metabolic demand because of β-cell secretory dysfunction and/or decreased β-cell mass. Defining the nature of the pancreatic islet defects present in T2D has been difficult, in part because human islets are inaccessible for direct study. This review is aimed to illustrate to what extent the Goto Kakizaki rat, one of the best characterized animal models of spontaneous T2D, has proved to be a valuable tool offering sufficient commonalities to study this aspect. A comprehensive compendium of the multiple functional GK abnormalities so far identified is proposed in this perspective, together with their time-course and interactions. A special focus is given toward the pathogenesis of defective β-cell number and function in the GK model. It is proposed that the development of T2D in the GK model results from the complex interaction of multiple events: (1) several susceptibility loci containing genes responsible for some diabetic traits; (2) gestational metabolic impairment inducing an epigenetic programming of the offspring pancreas and the major insulin target tissues; and (3) environmentally induced loss of β-cell differentiation due to chronic exposure to hyperglycemia/hyperlipidemia, inflammation, and oxidative stress.
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Affiliation(s)
- Bernard Portha
- Laboratoire B2PE (Biologie et Pathologie du Pancréas Endocrine), Unité BFA (Biologie Fonctionnelle et Adaptive), Université Paris-Diderot, CNRS EAC 4413, Paris, France.
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Nitric oxide, a janus-faced therapeutic target for diabetic microangiopathy-Friend or foe? Pharmacol Res 2011; 64:187-94. [PMID: 21635951 DOI: 10.1016/j.phrs.2011.05.009] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 05/17/2011] [Accepted: 05/17/2011] [Indexed: 01/21/2023]
Abstract
Accelerated atherosclerosis and microvascular complications are the leading causes of coronary heart disease, end-stage renal failure, acquired blindness and a variety of neuropathy, which could account for disabilities and high mortality rates in patients with diabetes. As the prevalence of diabetes has risen to epidemic proportions worldwide, diabetic vascular complications have now become one of the most challenging health problems. Nitric oxide (NO) is a pleiotropic molecule critical to a number of physiological and pathological processes in humans. NO not only inhibits the inflammatory-proliferative reactions in vascular wall cells, but also exerts anti-thrombogenic and endothelial cell protective properties, all of which could potentially be exploited as a therapeutic option for the treatment of vascular complications in diabetes. However, high amounts of NO produced by inducible NO synthase (iNOS) and/or peroxynitrite (ONOO(-)), a reactive intermediate of NO with superoxide anion are involved in pro-inflammatory reactions and tissue damage as well. This implies that NO is a janus-faced molecule and acts as a double-edged sword in vascular complications in diabetes. Further, NO is synthesized from l-arginine via the action of NO synthase (NOS), while NOS is blocked by endogenous l-arginine analogues such as asymmetric dimethylarginine (ADMA), a naturally occurring amino acid which is found in the plasma and various tissues. These findings suggest that amounts of NO locally produced, oxidative stress conditions and level of ADMA could determine the beneficial and detrimental effects of NO on vascular complications in diabetes. In this paper, we review the janus-faced aspects of NO in diabetic microangiopathy.
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Kim YH, Kim YS, Park SY, Park CH, Choi WS, Cho GJ. CaMKII regulates pericyte loss in the retina of early diabetic mouse. Mol Cells 2011; 31:289-93. [PMID: 21331776 PMCID: PMC3932701 DOI: 10.1007/s10059-011-0038-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 12/30/2010] [Accepted: 02/10/2011] [Indexed: 01/01/2023] Open
Abstract
Inducible nitric oxide synthase (iNOS) is an essential mediator in diabetic vascular lesions and known to be regulated by activation of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). The aim of this study was to investigate whether CaMKII affects iNOS-mediated pericyte death in the retina of diabetic mice with early stage disease. Total- and phospho-CaMKII, iNOS, and active caspase-3 protein levels were assessed by Western blotting, and CaMKII activity was measured by kinase assay. iNOS-related pericyte death was assessed by double immunofluorescent staining for iNOS and α-smooth muscle actin, followed by the TUNEL assay. Autocamtide-2-related inhibitory peptide (AIP), a specific inhibitor of CaMKII, was injected into the right vitreous 2 days before sacrifice of mice, to examine the effect of CaMKII inactivation in diabetic retinas. The levels of total- and phospho-CaMKII, iNOS, and active caspase-3 protein, and CaMKII activity were significantly increased in the diabetic retinas compared with those of control retinas. Furthermore, TUNEL-positive signals colocalized with iNOS-immunoreactive pericytes in the same retinas. However, inactivation of CaMKII by AIP treatment inhibited all these changes, which was accompanied by less pericyte loss. Our results demonstrate that CaMKII contributes to iNOS-related death of pericytes in the diabetic retina and that inactivation of this enzyme may be a potential treatment for retinal vascular lesion.
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Affiliation(s)
| | | | | | | | - Wan Sung Choi
- Department of Anatomy and Neurobiology, School of Medicine, Brain Korea 21 Biomedical Center, Gyeongsang National University, Jinju 660-751, Korea
| | - Gyeong Jae Cho
- Department of Anatomy and Neurobiology, School of Medicine, Brain Korea 21 Biomedical Center, Gyeongsang National University, Jinju 660-751, Korea
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Kim J, Kim OS, Kim CS, Kim NH, Kim JS. Cytotoxic role of methylglyoxal in rat retinal pericytes: Involvement of a nuclear factor-kappaB and inducible nitric oxide synthase pathway. Chem Biol Interact 2010; 188:86-93. [PMID: 20621070 DOI: 10.1016/j.cbi.2010.07.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 07/01/2010] [Accepted: 07/01/2010] [Indexed: 10/19/2022]
Abstract
Methylglyoxal (MGO), a cytotoxic metabolite, is produced from glycolysis. Elevated levels of MGO are observed in a number of diabetic complications, including retinopathy, nephropathy and cardiomyopathy. Loss of retinal pericyte, a hallmark of early diabetic retinal changes, leads to the development of formation of microaneurysms, retinal hemorrhages and neovasculization. Herein, we evaluated the cytotoxic role of MGO in retinal pericytes and further investigated the signaling pathway leading to cell death. Rat primary retinal pericytes were exposed to 400muM MGO for 6h. Retinal vessels were prepared from intravitreally MGO-injected rat eyes. We demonstrated apoptosis, nuclear factor-kappaB (NF-kappaB) activation and inducible nitric oxide synthase (iNOS) induction in cultured pericytes treated with MGO and MGO-injected retinal vessels. In MGO-treated pericytes, TUNEL-positive nuclei were markedly increased, and NF-kappaB was translocalized into the nuclei of pericytes, which paralleled the expression of iNOS. The treatment of pyrrolidine dithiocarbamate (an NF-kappaB inhibitor) or l-N6-(1-iminoethyl)-lysine (an iNOS inhibitor) prevented apoptosis of MGO-treated pericytes. In addition, in intravitreally MGO-injected rat eyes, TUNEL and caspase-3-positive pericytes were significantly increased, and activated NF-kappaB and iNOS were highly expressed. These results suggest that the increased expression of NF-kappaB and iNOS caused by MGO is involved in rat retinal pericyte apoptosis.
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Affiliation(s)
- Junghyun Kim
- Diabetic Complications Research Center, Division of Traditional Korean Medicine (TKM) Integrated Research, Korea Institute of Oriental Medicine (KIOM), 483 Exporo, Yuseong-gu, Daejeon 305-811, South Korea
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Enhancement of interleukin-1β-induced iNOS expression in cultured vascular smooth muscle cells of Goto–Kakizaki diabetes rats. Eur J Pharmacol 2010; 629:1-6. [DOI: 10.1016/j.ejphar.2009.11.054] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Revised: 11/18/2009] [Accepted: 11/24/2009] [Indexed: 11/23/2022]
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Sequence variation in DDAH1 and DDAH2 genes is strongly and additively associated with serum ADMA concentrations in individuals with type 2 diabetes. PLoS One 2010; 5:e9462. [PMID: 20209122 PMCID: PMC2830883 DOI: 10.1371/journal.pone.0009462] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 02/04/2010] [Indexed: 11/19/2022] Open
Abstract
Background Asymmetric dimethylarginine (ADMA), present in human serum, is an endogenous inhibitor of nitric oxide synthase and contributes to vascular disease. Dimethylarginine dimethylaminohydrolase (DDAH) is an ADMA degrading enzyme that has two isoforms: DDAHI and DDAHII. We sought to determine whether serum ADMA levels in type 2 diabetes are influenced by common polymorphisms in the DDAH1 and DDAH2 genes. Methodology/Principal Findings Relevant clinical parameters were measured and peripheral whole blood obtained for serum and genetic analysis on 343 participants with type 2 diabetes. Serum ADMA concentrations were determined by mass spectroscopy. Twenty six tag SNPs in the DDAH1 and 10 in the DDAH2 gene were genotyped in all subjects and tested for association with serum ADMA levels. Several SNPs and haplotypes in the DDAH genes were strongly associated with ADMA levels. Most significantly in the DDAH1 gene, rs669173 (p = 2.96×10−7), rs7521189 (p = 6.40×10−7), rs2474123 (p = 0.00082) and rs13373844 (p = 0.00027), and in the DDAH2 gene, rs3131383 (p = 0.0029) and the TGCCCAGGAG haplotype (p = 0.0012) were significantly associated with ADMA levels. Sub-analysis by diabetic retinopathy (DR) status revealed these variants were associated with ADMA levels predominantly in participants without DR. Combined analysis of the most strongly associated SNPs in DDAH1 (rs669173) and DDAH2 (rs3131383) revealed an additive effect (p = 1.37×10−8) on ADMA levels. Conclusions/Significance Genetic variation in the DDAH1 and 2 genes is significantly associated with serum ADMA levels. Further studies are required to determine the pathophysiological significance of elevated serum ADMA in type 2 diabetes and to better understand how DDAH gene variation influences ADMA levels.
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Pereira TDOS, da Costa GNF, Santiago ARS, Ambrósio AF, dos Santos PFM. High glucose enhances intracellular Ca2+ responses triggered by purinergic stimulation in retinal neurons and microglia. Brain Res 2010; 1316:129-38. [DOI: 10.1016/j.brainres.2009.12.034] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Revised: 12/11/2009] [Accepted: 12/12/2009] [Indexed: 01/06/2023]
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DeNiro M, Al-Halafi A, Al-Mohanna FH, Alsmadi O, Al-Mohanna FA. Pleiotropic effects of YC-1 selectively inhibit pathological retinal neovascularization and promote physiological revascularization in a mouse model of oxygen-induced retinopathy. Mol Pharmacol 2009; 77:348-67. [PMID: 20008515 DOI: 10.1124/mol.109.061366] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vascular endothelial growth factor (VEGF) and inducible nitric-oxide synthase (iNOS) have been implicated in ischemia-induced retinal neovascularization. Retinal ischemia has been shown to induce VEGF and iNOS expression. It has been postulated that one of the crucial consequences of iNOS expression in the ischemic retina is the inhibition of angiogenesis. Furthermore, iNOS was shown to be overexpressed in Müller cells from patients with diabetic retinopathy. YC-1, a small molecule inhibitor of hypoxia-inducible factor (HIF)-1 alpha, has been shown to inhibit iNOS expression in various tissue models. Our aim was to assess the pleiotropic effects of YC-1 in an oxygen-induced retinopathy (OIR) mouse model and evaluate its therapeutic potential in HIF-1- and iNOS-mediated retinal pathologies. Dual-injections of YC-1 into the neovascular retinas decreased the total retinopathy score, inhibited vaso-obliteration and pathologic tuft formation, and concomitantly promoted physiological retinal revascularization, compared with dimethyl sulfoxide (DMSO)-treated group. Furthermore, YC-1-treated retinas exhibited a marked increase in immunoreactivities for CD31 and von Willebrand factor and displayed significant inhibition in HIF-1alpha protein expression. Furthermore, YC-1 down-regulated VEGF, erythropoietin, endothelin-1, matrix metalloproteinase-9, and iNOS message and protein levels. When hypoxic Müller and neuoroglial cells were treated with YC-1, iNOS mRNA and protein levels were reduced in a dose-dependent fashion. We demonstrate that YC-1 inhibits pathological retinal neovascularization by exhibiting antineovascular activities, which impaired ischemia-induced expression of HIF-1 and its downstream angiogenic molecules. Furthermore, YC-1 enhanced physiological revascularization of the retinal vascular plexuses via the inhibition of iNOS mRNA and protein expressions. The pleiotropic effects of YC-1 allude to its possible use as a promising therapeutic iNOS inhibitor candidate for the treatment of retinal neovascularization.
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Affiliation(s)
- M DeNiro
- Research Department, King Khaled Eye Specialist Hospital, Aruba Street, P.O. Box.7191, Riyadh 11462, Kingdom of Saudi Arabia.
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Abstract
Para-inflammation is a tissue adaptive response to noxious stress or malfunction and has characteristics that are intermediate between basal and inflammatory states (Medzhitov, 2008). The physiological purpose of para-inflammation is to restore tissue functionality and homeostasis. Para-inflammation may become chronic or turn into inflammation if tissue stress or malfunction persists for a sustained period. Chronic para-inflammation contributes to the initiation and progression of many human diseases including obesity, type 2 diabetes, atherosclerosis, and age-related neurodegenerative diseases. Evidence from our studies and the studies of some others suggests that para-inflammation also exists in the aging retina in physiological conditions and might contribute to age-related retinal pathologies. The purpose of this review is to introduce the notion of "para-inflammation" as a state between frank, overt destructive inflammation and the non-inflammatory removal of dead or dying cells by apoptosis, to the retinal community. In diabetes and atherosclerosis, leukocytes particularly monocytes and vascular endothelial cells are constantly under noxious stress due to glycaemic and/or lipidaemic dysregulation. These blood-borne stresses trigger para-inflammatory responses in leukocytes and endothelial cells by up-regulating the expression of adhesion molecules or releasing cytokines/chemokines, which in turn cause abnormal leukocyte-endothelial interactions and ultimately vascular damage. In the aging retina, on the other hand, oxidized lipoproteins and free radicals are considered to be major causes of tissue stress and serve as local triggers for retinal para-inflammation. Microarray analysis has revealed the up-regulation of a large number of inflammatory genes, including genes involved in complement activation and inflammatory cytokine/chemokine production, in the aging retina. Para-inflammatory responses in the neuroretina of aged mice are characterized by microglial activation and subretinal migration, and breakdown of blood-retinal barrier. At the retinal/choroidal interface para-inflammation is manifested by complement activation in Bruch's membrane and RPE cells, and microglia accumulation in subretinal space. With age, para-inflammatory changes have also been observed in the choroidal tissue, evidenced by 1) increased thickness of choroid; 2) increased number of CD45(+)CRIg(+) macrophages; 3) morphological abnormalities in choroidal melanocytes; and 4) fibrosis in choroidal tissue. An increased knowledge of contribution of retinal para-inflammation to various pathological conditions is essential for the better understanding of the pathogenesis of various age-related retinal diseases including diabetic retinopathy, glaucoma and age-related macular degeneration.
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Affiliation(s)
- Heping Xu
- Immunology and Infection, Division of Applied Medicine, University of Aberdeen School of Medicine, Foresterhill, UK.
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Lu L, Xu H, Wang X, Guo G. Increased nitric oxide synthase activity is essential for electromagnetic-pulse-induced blood-retinal barrier breakdown in vivo. Brain Res 2009; 1264:104-10. [PMID: 19368824 DOI: 10.1016/j.brainres.2009.01.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Revised: 01/25/2009] [Accepted: 01/26/2009] [Indexed: 01/22/2023]
Abstract
PURPOSE To examine whether electromagnetic pulses (EMPs) affected the permeability of the blood-retinal barrier (BRB), gene expression of occludin and activity of nitric oxide synthase (NOS). METHODS Sprague-Dawley (SD) rats were used and randomized into EMP and control groups. Retinas were removed immediately, and 2 h or 24 h after EMP radiation. BRB permeability was analyzed by transmission electron microscopy and Evans Blue staining. Retinal NOS activity and concentrations of nitrite and nitrate were measured. Occludin mRNA and protein levels were detected by RT-PCR and Western blotting. RESULTS Exposure of SD rats to EMP resulted in increased BRB permeability, with the greatest decrease in occludin at 24 h. Moreover, this permeability defect was also correlated with significant increases in the formation of NO and induction of NOS activity in SD rats. Furthermore, we found that treatment with NOS inhibitor N-nitro-L-arginine methyl ester (L-NAME) blocked BRB breakdown and prevented the increase in NO formation and induction of NOS activity, as well as the decrease in occluding expression. CONCLUSION Taken together, these results support the view that NOS-dependent NO production is an important factor that contributes to EMP-induced BRB dysfunction, and suggests that NOS induction may play an important role in BRB breakdown.
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Affiliation(s)
- Lianjun Lu
- Department of Otolaryngology-Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China.
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Lee JH, Palaia T, Ragolia L. Impaired insulin-mediated vasorelaxation in diabetic Goto-Kakizaki rats is caused by impaired Akt phosphorylation. Am J Physiol Cell Physiol 2008; 296:C327-38. [PMID: 19052261 DOI: 10.1152/ajpcell.00254.2008] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Insulin resistance associated with Type 2 diabetes contributes to impaired vasorelaxation. Previously, we showed the phosphorylation of myosin-bound phosphatase substrate MYPT1, a marker of the vascular smooth muscle cell (VSMC) contraction, was negatively regulated by Akt (protein kinase B) phosphorylation in response to insulin stimulation. In this study we examined the role of Akt phosphorylation on impaired insulin-induced vasodilation in the Goto-Kakizaki (GK) rat model of Type 2 diabetes. GK VSMCs had impaired basal and insulin-induced Akt phosphorylation as well as increases in basal MYPT1 phosphorylation, inducible nitric oxide synthase (iNOS) expression, and nitrite/nitrate production compared with Wistar-Kyoto controls. Both iNOS expression and the inhibition of angiotensin (ANG) II-induced MYPT1 phosphorylation were resistant to the effects of insulin in diabetic GK VSMC. We also measured the isometric tension of intact and denuded GK aorta using a myograph and observed significantly impaired insulin-induced vasodilation. Adenovirus-mediated overexpression of constitutively active Akt in GK VSMC led to significantly improved insulin sensitivity in terms of counteracting ANG II-induced contractile signaling via MYPT1, myosin light chain dephosphorylation, and reduced iNOS expression, S-nitrosylation and survivin expression. We demonstrated for the first time the presence of Akt-independent iNOS expression in the GK diabetic model and that the defective insulin-induced vasodilation observed in the diabetic vasculature can be restored by the overexpression of active Akt, which advocates a novel therapeutic strategy for treating diabetes.
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Affiliation(s)
- Jin Hee Lee
- Vascular Biology Institute, Winthrop Univ. Hospital, 222 Station Plaza North, Rm. 505B, Mineola, NY 11501, USA
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Change in long-spacing collagen in Descemet's membrane of diabetic Goto-Kakizaki rats and its suppression by antidiabetic agents. EXPERIMENTAL DIABETES RESEARCH 2008; 2008:818341. [PMID: 18779868 PMCID: PMC2528061 DOI: 10.1155/2008/818341] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2008] [Revised: 04/23/2008] [Accepted: 07/01/2008] [Indexed: 11/23/2022]
Abstract
We examined changes in the ultrastructure and localization of major extracellular matrix components, including 5 types of collagen (type I, III, IV, VI, and VIII), laminin, fibronectin, and heparan sulfate proteoglycan in Descemet's membrane of the cornea of diabetic GK rats. In the cornea of diabetic GK rats, more long-spacing collagen fibrils were observed in Descemet's membrane than in the membrane of the nondiabetic Wistar rats. Both GK and Wistar rats showed an age-dependent increase in the density of the long-spacing collagen. Immunoelectron microscopy showed that type VIII collagen was localized in the internodal region of the long-spacing collagen, which was not labelled by any of the other antibodies used. The antidiabetic agents nateglinide and glibenclamide significantly suppressed the formation of the long-spacing collagen in the diabetic rats. Long-spacing collagen would thus be a useful indicator for studying diabetic changes in the cornea and the effect of antidiabetic agents.
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Inducible nitric oxide synthase mediates retinal DNA damage in Goto-Kakizaki rat retina. Jpn J Ophthalmol 2008; 52:314-322. [PMID: 18773271 DOI: 10.1007/s10384-008-0542-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Accepted: 01/22/2008] [Indexed: 12/19/2022]
Abstract
PURPOSE To examine the nitrosative and oxidative DNA damage induced by 8-nitroguanine and 8-hydroxy-2-deoxy guanosine (8-OHdG), and to determine the role played by inducible nitric oxide synthase (iNOS) in damage to DNA in the retina of the Goto-Kakizaki (GK) rat. METHODS Experiments were performed on GK rats, an animal model of spontaneous type 2 diabetes without obesity or visible diabetic vascular lesions. Immunohistochemistry was used to determine the retinal distribution of 8-nitroguanine, 8-OHdG, and iNOS in GK rats and control rats. The change in the expression of 8-nitroguanine and 8-OHdG in GK rats was also determined following an intravitreal injection of 1400W, an inhibitor of iNOS activity. RESULTS Immunohistochemical analysis showed that 8-nitroguanine and 8-OHdG were expressed strongly in the inner nuclear layer of GK retinas but only weakly in control retinas. This expression was correlated with an increase in the expression of iNOS in GK retinas, which was confirmed by the inhibition of iNOS activity by 1400W. CONCLUSION These findings demonstrate that iNOS plays a crucial role in nitrosative and oxidative DNA damage in GK rats, suggesting a retinal neurotoxic role of nitric oxide and superoxide in diabetic retinas.
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Takahashi Y, Nakano T, Wakabayashi I. Increased induction of inducible nitric oxide synthase expression in aortae of type 2 diabetes rats. J Pharmacol Sci 2008; 107:190-200. [PMID: 18566522 DOI: 10.1254/jphs.fp0080010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
The aim of this study was to determine whether the pathway of inducible NO synthase (iNOS) in blood vessels is changed by type 2 diabetes. Lipopolysaccharide (LPS)-induced nitric oxide (NO) production and expression of iNOS and effects of LPS on phenylephrine-induced contractile force were compared in aortae isolated from Goto-Kakizaki (G-K) diabetes rats and aortae isolated from control Wistar rats. Both LPS-stimulated nitrite generation and iNOS expression levels were significantly higher in aortae from G-K rats than in those from control rats. Phenylephrine-induced contractile force in the presence of LPS was significantly lower in aortae from G-K rats than in those from control rats, while contractile force in the absence of LPS was comparable in the diabetic and control groups. On the other hand, incubation of aortae in high glucose-containing medium did not affect the LPS-stimulated nitrite accumulation and iNOS expression and the phenylephrine-induced contractile force, regardless of the presence of LPS. These results suggest that LPS-induced NO production through the iNOS pathway is increased and subsequent attenuation of contractile force by excess NO is enhanced in arteries of rats with type 2 diabetes.
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Affiliation(s)
- Yuji Takahashi
- Department of Environmental and Preventive Medicine, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
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Contributions of inflammatory processes to the development of the early stages of diabetic retinopathy. EXPERIMENTAL DIABETES RESEARCH 2008; 2007:95103. [PMID: 18274606 PMCID: PMC2216058 DOI: 10.1155/2007/95103] [Citation(s) in RCA: 450] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2007] [Accepted: 05/27/2007] [Indexed: 12/11/2022]
Abstract
Diabetes causes metabolic and physiologic abnormalities in the retina, and these changes suggest a role for inflammation in the development of diabetic retinopathy. These changes include upregulation of iNOS, COX-2, ICAM-1, caspase 1, VEGF, and NF-κB, increased production of nitric oxide, prostaglandin E2, IL-1β, and cytokines, as well as increased permeability and leukostasis. Using selective pharmacologic inhibitors or genetically modified animals, an increasing number of therapeutic approaches have been identified that significantly inhibit development of at least the early stages of diabetic retinopathy, especially occlusion and degeneration of retinal capillaries. A common feature of a number of these therapies is that they inhibit production of inflammatory mediators. The concept that localized inflammatory processes play a role in the development of diabetic retinopathy is relatively new, but evidence that supports the hypothesis is accumulating rapidly. This new hypothesis offers new insight into the pathogenesis of diabetic retinopathy, and offers novel targets to inhibit the ocular disease.
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Fletcher EL, Downie LE, Ly A, Ward MM, Batcha AH, Puthussery T, Yee P, Hatzopoulos KM. A review of the role of glial cells in understanding retinal disease. Clin Exp Optom 2008; 91:67-77. [PMID: 18045252 DOI: 10.1111/j.1444-0938.2007.00204.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Retinal vascular diseases such as diabetic retinopathy and retinopathy of prematurity are major causes of visual loss. Although the focus of a great deal of research has been on the aetiology of vascular growth, it is now emerging that anomalies in other retinal cell types, especially glial cells, occur very early in the course of the disease. Glial cells have major roles in every stage of disease, from the earliest subtle variations in neural function, to the development of epi-retinal membranes and tractional detachment. Therefore, having a firm understanding of the function of retinal glia is important in our understanding of retinal disease and is crucial for the development of new treatment strategies.
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Affiliation(s)
- Erica L Fletcher
- Department of Anatomy and Cell Biology, The University of Melbourne, Victoria, Australia.
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Abstract
PURPOSE The use of biopolymers in peribulbar injection for controlled drug delivery provides alternative options to eyedrops and intravitreal or surgical methods. Polymerizable biopolymers are especially likely to have a role because of their particular properties. In liquid form, they can be easily injected into the target site and, after polymerization, they provide a prolonged and controlled release of the drug. This study was undertaken to demonstrate the suitability of a thermopolymerizable biopolymer poloxamer (Lutrol F127) for peribulbar injections and controlled drug release. METHODS The toxicity of injected poloxamer compounds was evaluated by visual inspection and histological and immunohistochemical tissue evaluation. The release of marker substances such as 5(6)-carboxyfluorescein (376 Da) or fluorescein isothiocyanate-dextran (FITC-dextran) (4-40 kDa) from poloxamer was used to simulate drug release and penetration into the eye using in vivo fluorometry. RESULTS According to our clinical and pathological analyses, poloxamer was well tolerated in peribulbar injections and did not cause acute toxicity at the site of injection. The marker compounds were released from the site of injection during the first 24 hours. CONCLUSIONS Although poloxamer appears to be suitable for peribulbar injections, a more prolonged period of dissolution is desirable for clinical purposes.
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Affiliation(s)
- Katja Vehanen
- Department of Ophthalmology, University of Kuopio, Kuopio, Finland.
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Inducible nitric oxide synthase depresses cardiac contractile function in Zucker diabetic fatty rats. Eur J Pharmacol 2008; 579:253-9. [DOI: 10.1016/j.ejphar.2007.09.043] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2007] [Revised: 09/21/2007] [Accepted: 09/27/2007] [Indexed: 10/22/2022]
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Curtis TM, Stitt AW, McGahon MK, Scholfield CN, McGeown JG. New developments in diabetic retinopathy. EXPERT REVIEW OF OPHTHALMOLOGY 2007. [DOI: 10.1586/17469899.2.6.947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Zheng L, Du Y, Miller C, Gubitosi-Klug RA, Kern TS, Ball S, Berkowitz BA. Critical role of inducible nitric oxide synthase in degeneration of retinal capillaries in mice with streptozotocin-induced diabetes. Diabetologia 2007; 50:1987-1996. [PMID: 17583794 DOI: 10.1007/s00125-007-0734-9] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Accepted: 04/30/2007] [Indexed: 12/13/2022]
Abstract
AIMS/HYPOTHESIS Diabetes results in the upregulation of the production of several components of the inflammatory response in the retina, including inducible nitric oxide synthase (iNOS). The aim of this study was to investigate the role of iNOS in the pathogenesis of the early stages of diabetic retinopathy using iNOS-deficient mice (iNos (-/-)). MATERIALS AND METHODS iNos (-/-) mice and wild-type (WT; C57BL/6J) mice were made diabetic with streptozotocin or kept as non-diabetic controls. Mice were killed at different time points after the induction of diabetes for assessment of vascular histopathology, cell loss in the ganglion cell layer (GCL), retinal thickness, and biochemical and physiological abnormalities. RESULTS The concentrations of nitric oxide, nitration of proteins, poly(ADP-ribose) (PAR)-modified proteins, endothelial nitric oxide synthase, prostaglandin E(2), superoxide and leucostasis were significantly (p < 0.05) increased in retinas of WT mice diabetic for 2 months compared with non-diabetic WT mice. All of these abnormalities except PAR-modified proteins in retinas were inhibited (p < 0.05) in diabetic iNos (-/-) mice. The number of acellular capillaries and pericyte ghosts was significantly increased in retinas from WT mice diabetic for 9 months compared with non-diabetic WT controls, these increases being significantly inhibited in diabetic iNos (-/-) mice (p < 0.05 for all). Retinas from WT diabetic mice were significantly thinner than those from their non-diabetic controls, whereas diabetic iNos (-/-) mice were protected from this abnormality. We found no evidence of cell loss in the GCL of diabetic WT or iNos (-/-) mice. Deletion of iNos had no beneficial effect on diabetes-induced abnormalities on the electroretinogram. CONCLUSIONS/INTERPRETATION We demonstrate that the inflammatory enzyme iNOS plays an important role in the pathogenesis of vascular lesions characteristic of the early stages of diabetic retinopathy in mice.
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Affiliation(s)
- L Zheng
- Department of Medicine, 448B Biomedical Research Building, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA.
| | - Y Du
- Department of Medicine, 448B Biomedical Research Building, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - C Miller
- Department of Medicine, 448B Biomedical Research Building, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
- Alcon Research, Fort Worth, TX, USA
| | - R A Gubitosi-Klug
- Department of Pediatrics, Rainbow Babies and Children's Hospital, Case Western Reserve University, Cleveland, OH, USA
| | - T S Kern
- Department of Medicine, 448B Biomedical Research Building, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA.
- Department of Ophthalmology, 434 Biomedical Research Building, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA.
- Cleveland VAMC Research Service 151, Cleveland, OH, USA.
| | - S Ball
- Cleveland VAMC Research Service 151, Cleveland, OH, USA
| | - B A Berkowitz
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, MI, USA
- Department of Ophthalmology, Wayne State University, Detroit, MI, USA
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Ellis EA, Sengupta N, Caballero S, Guthrie SM, Mames RN, Grant MB. Nitric oxide synthases modulate progenitor and resident endothelial cell behavior in galactosemia. Antioxid Redox Signal 2005; 7:1413-22. [PMID: 16356104 DOI: 10.1089/ars.2005.7.1413] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We used knockout animals of either inducible nitric oxide synthase (iNOS(/)) or endothelial NOS (eNOS(/)) to characterize the role of NOS in galactosemia, a model of diabetic retinopathy. NADH oxidase and nitrotyrosine were used as biomarkers of oxidative stress and vascular dysfunction. These animals were engrafted with hematopoietic stem cells (HSC) expressing green fluorescence protein (gfp(+)) to characterize the contribution of HSC and endothelial progenitor cells to neovascularization. Increased NADH oxidase activity and superoxide generation occurred in all galactose-fed mice. eNOS(/) mice demonstrated increased iNOS immunoreactivity in their retinal vasculature. Nitrotyrosine levels were low at baseline in the wild-type (WT) mice, eNOS(/) and iNOS(/) mice, and the galactose-fed iNOS mice and increased following galactose feeding in eNOS(/) and WT. Galactose-fed WT.gfp and iNOS(/).gfp chimeric animals had areas of perfused new vessels composed of gfp(+) cells. In contrast, galactose-fed eNOS(/).gfp mice produced copious, unbranched, nonperfused tubes. Thus, nitric oxide modulates HSC behavior and vascular phenotype in the retina. Although there is increased NADH oxidase and superoxide in galactosemic mice of all isoforms, iNOS is the source of nitric oxide responsible for peroxynitrite and nitrotyrosine formation that leads to the pathology observed in galactosemic mice.
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Affiliation(s)
- E Ann Ellis
- Microscopy and Imaging Center, Texas A&M University, College Station, TX, USA
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