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Protective Effects of Melatonin on Retinal Inflammation and Oxidative Stress in Experimental Diabetic Retinopathy. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:3528274. [PMID: 27143993 PMCID: PMC4837288 DOI: 10.1155/2016/3528274] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 03/14/2016] [Accepted: 03/17/2016] [Indexed: 12/11/2022]
Abstract
Oxidative stress and inflammation are important pathogenic factors contributing to the etiology of diabetic retinopathy (DR). Melatonin is an endogenous hormone that exhibits a variety of biological effects including antioxidant and anti-inflammatory functions. The goals of this study were to determine whether melatonin could ameliorate retinal injury and to explore the potential mechanisms. Diabetes was induced by a single intraperitoneal (i.p.) injection of STZ (60 mg/kg) in Sprague-Dawley rats. Melatonin (10 mg kg(-1) daily, i.p.) was administered from the induction of diabetes and continued for up to 12 weeks, after which the animals were sacrificed and retinal samples were collected. The retina of diabetic rats showed depletion of glutathione and downregulation of glutamate cysteine ligase (GCL). Melatonin significantly upregulated GCL by retaining Nrf2 in the nucleus and stimulating Akt phosphorylation. The production of proinflammatory cytokines and proteins, including interleukin 1β, TNF-α, and inducible nitric oxide synthase (iNOS), was inhibited by melatonin through the NF-κB pathway. At 12 weeks, melatonin prevented the significant decrease in the ERG a- and b-wave amplitudes under the diabetic condition. Our results suggest potent protective functions of melatonin in diabetic retinopathy. In addition to being a direct antioxidant, melatonin can exert receptor-mediated signaling effects to attenuate inflammation and oxidative stress of the retina.
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Implications of the endogenous PPAR-gamma ligand, 15-deoxy-delta-12, 14-prostaglandin J2, in diabetic retinopathy. Life Sci 2016; 153:93-9. [PMID: 27060220 DOI: 10.1016/j.lfs.2016.03.054] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 03/24/2016] [Accepted: 03/29/2016] [Indexed: 01/09/2023]
Abstract
Diabetic retinopathy, a common secondary complication of diabetes mellitus, involves extensive damage to the retinal microvasculature. Retina, being a susceptible target, is highly prone to hyperglycemia-induced molecular damages. PPAR receptor, chiefly gamma subtype, mediates numerous responses related to glucose metabolism and hence is utilized, through its agonism, for the restoration of normal insulin sensitivity and glucose homeostasis in the body. Although a number of synthetic PPAR-gamma receptor agonists have been developed and are being employed for treatment purposes, the role of its endogenous ligand in the prevention of diabetic retinopathy is poorly acknowledged. Activation of PPAR-gamma receptor, via endogenous agents, provides a natural defensive shield against various hyperglycemia-induced pathological conditions. Although the biological levels of 15d-PGJ2 (an endogenous agonist of PPAR-gamma receptor) are found to be below the concentration required to trigger PPAR-gamma-mediated actions, employment of several advanced methods for the exogenous administration of this ligand might provide a beneficial option. Besides, 15d-PGJ2-induced defense is better than any of the newly developed alternative therapies, such as anti-inflammatory, anti-angiogenic or anti-apoptotic agents, of diabetic retinopathy, since it singularly provides, virtually, a complete protection package against all these pathological eventualities. Therefore, the physiology of this endogenous PPAR-gamma ligand might, possibly, be exploited to a great extent for the development of prophylactic agents, in order to restrict the progression of diabetic retinopathy.
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103
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Zhang Y, Du Y, He JF, Li KJ. 8-iso-prostaglandin-F2α: a possible trigger or accelerator of diabetic retinopathy. Int J Ophthalmol 2016; 9:163-5. [PMID: 26949628 DOI: 10.18240/ijo.2016.01.27] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Accepted: 05/06/2015] [Indexed: 11/23/2022] Open
Affiliation(s)
- Ying Zhang
- Department of Ophthalmology, the First Affiliated Hospital of Guangxi Medical University, Nanning 530021, Guangxi Zhuang Autonomous Region, China
| | - Yi Du
- Department of Ophthalmology, the First Affiliated Hospital of Guangxi Medical University, Nanning 530021, Guangxi Zhuang Autonomous Region, China
| | - Jian-Feng He
- Department of Ophthalmology, the First Affiliated Hospital of Guangxi Medical University, Nanning 530021, Guangxi Zhuang Autonomous Region, China
| | - Kai-Jun Li
- Department of Ophthalmology, the First Affiliated Hospital of Guangxi Medical University, Nanning 530021, Guangxi Zhuang Autonomous Region, China
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Fangueiro JF, Calpena AC, Clares B, Andreani T, Egea MA, Veiga FJ, Garcia ML, Silva AM, Souto EB. Biopharmaceutical evaluation of epigallocatechin gallate-loaded cationic lipid nanoparticles (EGCG-LNs): In vivo, in vitro and ex vivo studies. Int J Pharm 2016; 502:161-9. [PMID: 26921515 DOI: 10.1016/j.ijpharm.2016.02.039] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 02/21/2016] [Accepted: 02/22/2016] [Indexed: 01/08/2023]
Abstract
Cationic lipid nanoparticles (LNs) have been tested for sustained release and site-specific targeting of epigallocatechin gallate (EGCG), a potential polyphenol with improved pharmacological profile for the treatment of ocular pathologies, such as age-related macular edema, diabetic retinopathy, and inflammatory disorders. Cationic EGCG-LNs were produced by double-emulsion technique; the in vitro release study was performed in a dialysis bag, followed by the drug assay using a previously validated RP-HPLC method. In vitro HET-CAM study was carried out using chicken embryos to determine the potential risk of irritation of the developed formulations. Ex vivo permeation profile was assessed using rabbit cornea and sclera isolated and mounted in Franz diffusion cells. The results show that the use of cationic LNs provides a prolonged EGCG release, following a Boltzmann sigmoidal profile. In addition, EGCG was successfully quantified in both tested ocular tissues, demonstrating the ability of these formulations to reach both anterior and posterior segment of the eye. The pharmacokinetic study of the corneal permeation showed a first order kinetics for both cationic formulations, while EGCG-cetyltrimethylammonium bromide (CTAB) LNs followed a Boltzmann sigmoidal profile and EGCG-dimethyldioctadecylammonium bromide (DDAB) LNs a first order profile. Our studies also proved the safety and non-irritant nature of the developed LNs. Thus, loading EGCG in cationic LNs is recognised as a promising strategy for the treatment of ocular diseases related to anti-oxidant and anti-inflammatory pathways.
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Affiliation(s)
- Joana F Fangueiro
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra (FFUC), Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal; Centre for Research and Technology of Agro-Environmental and Biological Sciences (CITAB-UTAD), Quinta de Prados, 5001-801 Vila Real, Portugal; Center for Neuroscience and Cell Biology (CNC), University of Coimbra (FFUC), Coimbra, Portugal
| | - Ana C Calpena
- Department of Pharmacy and Pharmaceutical Technology, Faculty of Pharmacy, University of Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain; Institute of Nanoscience and Nanotechnology, University of Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain
| | - Beatriz Clares
- Department of Pharmacy and Pharmaceutical Technology, School of Pharmacy, University of Granada, Campus of Cartuja s/n, 18071 Granada, Spain
| | - Tatiana Andreani
- Centre for Research and Technology of Agro-Environmental and Biological Sciences (CITAB-UTAD), Quinta de Prados, 5001-801 Vila Real, Portugal; Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto (FCUP), Campo Alegre 4160-007 Porto, Portugal
| | - Maria A Egea
- Institute of Nanoscience and Nanotechnology, University of Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain; Department of Physical Chemistry, Faculty of Pharmacy, University of Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain
| | - Francisco J Veiga
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra (FFUC), Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal; Center for Neuroscience and Cell Biology (CNC), University of Coimbra (FFUC), Coimbra, Portugal
| | - Maria L Garcia
- Institute of Nanoscience and Nanotechnology, University of Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain; Department of Physical Chemistry, Faculty of Pharmacy, University of Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain
| | - Amélia M Silva
- Centre for Research and Technology of Agro-Environmental and Biological Sciences (CITAB-UTAD), Quinta de Prados, 5001-801 Vila Real, Portugal; Department of Biology and Environment, University of Trás-os Montes e Alto Douro (UTAD), Quinta de Prados; 5001-801 Vila Real, Portugal
| | - Eliana B Souto
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra (FFUC), Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal; Center for Neuroscience and Cell Biology (CNC), University of Coimbra (FFUC), Coimbra, Portugal.
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105
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Klettner A. Fucoidan as a Potential Therapeutic for Major Blinding Diseases--A Hypothesis. Mar Drugs 2016; 14:E31. [PMID: 26848666 PMCID: PMC4771984 DOI: 10.3390/md14020031] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 01/12/2016] [Accepted: 01/22/2016] [Indexed: 12/23/2022] Open
Abstract
Fucoidan is a heterogeneous group of sulfated polysaccharide with a high content of l-fucose, which can be extracted from brown algae and marine invertebrates. It has many beneficial biological activities that make fucoidan an interesting candidate for therapeutic application in a variety of diseases. Age-related macular degeneration and diabetic retinopathy are major causes for vision loss and blindness in the industrialized countries and increasingly in the developing world. Some of the characteristics found in certain fucoidans, such as its anti-oxidant activity, complement inhibition or interaction with the Vascular Endothelial Growth factor, which would be of high interest for a potential application of fucoidan in age-related macular degeneration or diabetic retinopathy. However, the possible usage of fucoidan in ophthalmological diseases has received little attention so far. In this review, biological activities of fucoidan that could be of interest regarding these diseases will be discussed.
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Affiliation(s)
- Alexa Klettner
- Department of Ophthalmology, University Medical Center, University of Kiel, 24105 Kiel, Germany.
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106
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Klein R, Myers CE, Lee KE, Paterson AD, Cruickshanks KJ, Tsai MY, Gangnon RE, Klein BEK. Oxidized Low-Density Lipoprotein and the Incidence of Proliferative Diabetic Retinopathy and Clinically Significant Macular Edema Determined From Fundus Photographs. JAMA Ophthalmol 2015; 133:1054-61. [PMID: 26181138 DOI: 10.1001/jamaophthalmol.2015.2239] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
IMPORTANCE Studies have shown oxidized low-density lipoprotein to be associated with the incidence of proliferative retinopathy and other complications of type 1 diabetes mellitus. Because low-risk interventions are available to modify oxidized low-density lipoprotein, it is important to examine the relationships between this factor and the incidence of proliferative retinopathy and of macular edema, 2 important causes of visual impairment in people with type 1 diabetes. OBJECTIVE To determine the association of oxidized low-density lipoprotein with the worsening of diabetic retinopathy and the incidence of proliferative retinopathy and of macular edema. DESIGN, SETTING, AND PARTICIPANTS Of 996 participants with type 1 diabetes in the Wisconsin Epidemiologic Study of Diabetic Retinopathy, 730 were examined up to 4 times (1990-1992, 1994-1996, 2005-2007, and 2012-2014) over 24 years and had assays of oxidized low-density lipoprotein and fundus photographs gradable for diabetic retinopathy and macular edema. Analyses started July 2014 and ended February 2015. MAIN OUTCOMES AND MEASURES Worsening of diabetic retinopathy, incidence of proliferative diabetic retinopathy, and incidence of macular edema as assessed via grading of color stereo film fundus photographs. The levels of oxidized low-density lipoprotein collected from serum samples at the time of each examination were measured in 2013 and 2014 from frozen serum. RESULTS The cohort at baseline had a mean (SD) level of oxidized low-density lipoprotein of 30.0 (8.5) U/L. While adjusting for duration of diabetes, glycated hemoglobin A1c level, and other factors, we found that neither the level of oxidized low-density lipoprotein at the beginning of a period nor the change in it over a certain period was associated with the incidence of proliferative diabetic retinopathy (hazard ratio [HR], 1.11 [95% CI, 0.91-1.35], P = .30; odds ratio [OR], 1.77 [95% CI, 0.99-3.17], P = .06), the incidence of macular edema (HR, 1.04 [95% CI, 0.83-1.29], P = .74; OR, 1.08 [95% CI, 0.44-2.61], P = .87), or the worsening of diabetic retinopathy (HR, 0.94 [95% CI, 0.83-1.07], P = .34; OR, 1.32 [95% CI, 0.83-2.09], P = .24). CONCLUSIONS AND RELEVANCE Our findings do not provide evidence for a relationship between increasing levels of serum oxidized low-density lipoprotein and the incidence of macular edema or the worsening of diabetic retinopathy in persons with type 1 diabetes. The potential increase in the HR for incident proliferative retinopathy, with an increase in oxidized low-density lipoprotein level over the preceding period, warrants further investigation of this relationship.
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Affiliation(s)
- Ronald Klein
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison
| | - Chelsea E Myers
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison
| | - Kristine E Lee
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison
| | - Andrew D Paterson
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Karen J Cruickshanks
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison3Department of Population Health Sciences, University of Wisconsin School of Medicine and Public Health, Madison
| | - Michael Y Tsai
- Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, Minneapolis
| | - Ronald E Gangnon
- Department of Biostatistics and Medical Informatics, University of Wisconsin School of Medicine and Public Health, Madison
| | - Barbara E K Klein
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison
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107
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Lee R, Wong TY, Sabanayagam C. Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss. EYE AND VISION 2015. [PMID: 26605370 DOI: 10.1186/s40662-015-0026-2 10.1186/s40662-015-0026-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Diabetic retinopathy (DR) is a leading cause of vision-loss globally. Of an estimated 285 million people with diabetes mellitus worldwide, approximately one third have signs of DR and of these, a further one third of DR is vision-threatening DR, including diabetic macular edema (DME). The identification of established modifiable risk factors for DR such as hyperglycemia and hypertension has provided the basis for risk factor control in preventing onset and progression of DR. Additional research investigating novel risk factors has improved our understanding of multiple biological pathways involved in the pathogenesis of DR and DME, especially those involved in inflammation and oxidative stress. Variations in DR prevalence between populations have also sparked interest in genetic studies to identify loci associated with disease susceptibility. In this review, major trends in the prevalence, incidence, progression and regression of DR and DME are explored, and gaps in literature identified. Established and novel risk factors are also extensively reviewed with a focus on landmark studies and updates from the recent literature.
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Affiliation(s)
- Ryan Lee
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore ; Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Tien Y Wong
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore ; Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore ; Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Charumathi Sabanayagam
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore ; Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore ; Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Graduate Medical School, Singapore, Singapore
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108
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Lee R, Wong TY, Sabanayagam C. Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss. EYE AND VISION (LONDON, ENGLAND) 2015. [PMID: 26605370 DOI: 10.1186/s40662-015-0026-2+10.1186/s40662-015-0026-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Diabetic retinopathy (DR) is a leading cause of vision-loss globally. Of an estimated 285 million people with diabetes mellitus worldwide, approximately one third have signs of DR and of these, a further one third of DR is vision-threatening DR, including diabetic macular edema (DME). The identification of established modifiable risk factors for DR such as hyperglycemia and hypertension has provided the basis for risk factor control in preventing onset and progression of DR. Additional research investigating novel risk factors has improved our understanding of multiple biological pathways involved in the pathogenesis of DR and DME, especially those involved in inflammation and oxidative stress. Variations in DR prevalence between populations have also sparked interest in genetic studies to identify loci associated with disease susceptibility. In this review, major trends in the prevalence, incidence, progression and regression of DR and DME are explored, and gaps in literature identified. Established and novel risk factors are also extensively reviewed with a focus on landmark studies and updates from the recent literature.
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Affiliation(s)
- Ryan Lee
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore ; Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Tien Y Wong
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore ; Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore ; Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Charumathi Sabanayagam
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore ; Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore ; Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Graduate Medical School, Singapore, Singapore
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109
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Mohamed R, El-Remessy AB. Imbalance of the Nerve Growth Factor and Its Precursor: Implication in Diabetic Retinopathy. ACTA ACUST UNITED AC 2015; 6. [PMID: 26807305 PMCID: PMC4721560 DOI: 10.4172/2155-9570.1000483] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Diabetic retinopathy is the leading cause of blindness in working age in US and worldwide. Neurotrophins including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and neurotrophin-4 (NT-4) are known to be essential for growth, differentiation and survival of neurons in the developing and mature retina. Nevertheless, a growing body of evidence supports an emerging role of neurotrophins in retinal diseases and in particular, diabetic retinopathy. Neurotrophins are initially synthesized in a pro-form and undergo proteolytic cleavage to produce the mature form that activates two distinctive receptors, the tyrosine kinase tropomycin receptor (Trk) and, to lesser extent, the common low affinity p75 neurotrophin receptor (p75NTR). Despite tight glycemic and metabolic control, many diabetic patients continue to experience progressive retinal damage. Understanding the molecular events involved in diabetic retinopathy is extremely important to identify novel therapeutic strategies to halt the disease progression. Diabetes induces imbalance in neurotrophins by increasing its proform, which is associated with upregulation of the p75NTR receptor in the retina. A growing body of evidence supports a link between the imbalance of pro-neurotrophins and early retinal inflammation, neuro-and microvascular degeneration. Therefore, examining changes in the levels of neurotrophins and its receptors might provide a therapeutically beneficial target to combat disease progression in diabetic patients. This commentary aims to highlight the impact of diabetes-impaired balance of neurotrophins and in particular, the NGF and its receptors; TrkA and p75NTR in the pathology of DR.
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Affiliation(s)
- Riyaz Mohamed
- Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, USA ; Culver Vision Discovery Institute, Georgia Regents University, USA ; Charlie Norwood Veterans Affairs Medical Center, Augusta, Georgia, USA
| | - Azza B El-Remessy
- Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, USA ; Culver Vision Discovery Institute, Georgia Regents University, USA ; Charlie Norwood Veterans Affairs Medical Center, Augusta, Georgia, USA
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110
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Kumar B, Kowluru A, Kowluru RA. Lipotoxicity augments glucotoxicity-induced mitochondrial damage in the development of diabetic retinopathy. Invest Ophthalmol Vis Sci 2015; 56:2985-92. [PMID: 26024084 DOI: 10.1167/iovs.15-16466] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
PURPOSE Although hyperglycemia is the main instigator in the development of diabetic retinopathy, dyslipidemia is also considered to play an important role. In the pathogenesis of diabetic retinopathy, cytosolic NADPH oxidase 2 (Nox2) is activated before retinal mitochondria are damaged. Our aim was to investigate the effect of lipids in the development of diabetic retinopathy. METHODS Reactive oxygen species (ROS, by 2',7'-dichlorofluorescein diacetate) and activities of Nox2 (by a lucigenin-based method) and Rac1 (by G-LISA) were quantified in retinal endothelial cells incubated with 50 μM palmitate in 5 mM glucose (lipotoxicity) or 20 mM glucose (glucolipotoxicity) for 6 to 96 hours. Mitochondrial DNA (mtDNA) damage was evaluated by extended-length PCR and its transcription by quantifying cytochrome b transcripts. RESULTS Within 6 hours of exposure of endothelial cells to lipotoxicity, or glucotoxicity (20 mM glucose, without palmitate), significant increase in ROS, Nox2, and Rac1 was observed, which was exacerbated by glucolipotoxic insult. At 48 hours, neither lipotoxicity nor glucotoxicity had any effect on mtDNA and its transcription, but glucolipotoxicity significantly damaged mtDNA and decreased cytochrome b transcripts, and at 96 hours, glucotoxicity and glucolipotoxicity produced similar detrimental effects on mitochondrial damage. CONCLUSIONS Although during initial exposure, lipotoxic or glucotoxic insult produces similar increase in ROS, addition of lipotoxicity in a glucotoxic environment further exacerbates ROS production, and also accelerates their damaging effects on mitochondrial homeostasis. Thus, modulation of Nox2 by pharmacological agents in prediabetic patients with dyslipidemia could retard the development of retinopathy before their hyperglycemia is observable.
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Affiliation(s)
- Binit Kumar
- Kresge Eye Institute Wayne State University, Detroit, Michigan, United States
| | - Anjan Kowluru
- Pharmaceutical Sciences, Wayne State University, Detroit, Michigan, United States 3ß-Cell Biochemistry Laboratory, John D. Dingell VA Medical Center, Detroit, Michigan, United States
| | - Renu A Kowluru
- Kresge Eye Institute Wayne State University, Detroit, Michigan, United States
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111
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Lee R, Wong TY, Sabanayagam C. Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss. EYE AND VISION 2015; 2:17. [PMID: 26605370 PMCID: PMC4657234 DOI: 10.1186/s40662-015-0026-2] [Citation(s) in RCA: 863] [Impact Index Per Article: 95.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 09/01/2015] [Indexed: 12/15/2022]
Abstract
Diabetic retinopathy (DR) is a leading cause of vision-loss globally. Of an estimated 285 million people with diabetes mellitus worldwide, approximately one third have signs of DR and of these, a further one third of DR is vision-threatening DR, including diabetic macular edema (DME). The identification of established modifiable risk factors for DR such as hyperglycemia and hypertension has provided the basis for risk factor control in preventing onset and progression of DR. Additional research investigating novel risk factors has improved our understanding of multiple biological pathways involved in the pathogenesis of DR and DME, especially those involved in inflammation and oxidative stress. Variations in DR prevalence between populations have also sparked interest in genetic studies to identify loci associated with disease susceptibility. In this review, major trends in the prevalence, incidence, progression and regression of DR and DME are explored, and gaps in literature identified. Established and novel risk factors are also extensively reviewed with a focus on landmark studies and updates from the recent literature.
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Affiliation(s)
- Ryan Lee
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore ; Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Tien Y Wong
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore ; Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore ; Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Charumathi Sabanayagam
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore ; Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore ; Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Graduate Medical School, Singapore, Singapore
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112
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Associations of FPG, A1C and disease duration with protein markers of oxidative damage and antioxidative defense in type 2 diabetes and diabetic retinopathy. Eye (Lond) 2015; 29:1585-93. [PMID: 26381098 DOI: 10.1038/eye.2015.177] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Accepted: 07/12/2015] [Indexed: 12/31/2022] Open
Abstract
PURPOSE To investigate the role of protein oxidative damage and antioxidant defense in relationship to hyperglycemia measured as fasting plasma glucose (FPG), glycated hemoglobin (A1C), and duration of disease in type 2 diabetes mellitus (DM) and diabetic retinopathy (DR). METHODS This study recruited 23 non-diabetic subjects, 16 DM patients without any complications and 18 DR patients. The serum ischemia modified albumin (IMA) and glutathione (GSH) levels were measured. The IMA results were corrected for serum albumin. Between-group differences were studied by analysis of variance and between-variable associations were studied by Spearman's and partial correlations. RESULTS IMA and cIMA values were elevated, whereas GSH was decreased in both patient groups vs controls (P<0.05), and the increase in IMA formation is not related to serum albumin changes. DR patients have much severe oxidative stress (OS) status with high IMA and cIMA, and low GSH than in the DM group (P<0.05). Both FPG and A1C levels were positively associated with IMA in DM group, while in the DR group, duration of disease too had a positive association with IMA. The antioxidant GSH had negative correlations with FPG (r=-0.52, P=0.02) and IMA (r=-0.49, P=0.03) in the DR group. Partial correlation analyses predicted mutual or independent associations among parameters. CONCLUSIONS Severe OS in DR has been associated with increased FPG, A1C, and disease duration. Both hyperglycemia and elevated oxidative damage detected as IMA are collectively associated with depleted GSH status. Our study unravels the need for monitoring of OS in addition to standard glycemic management in DR.
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113
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The progress in understanding and treatment of diabetic retinopathy. Prog Retin Eye Res 2015; 51:156-86. [PMID: 26297071 DOI: 10.1016/j.preteyeres.2015.08.001] [Citation(s) in RCA: 630] [Impact Index Per Article: 70.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 08/12/2015] [Accepted: 08/13/2015] [Indexed: 12/15/2022]
Abstract
Diabetic retinopathy is the most frequently occurring complication of diabetes mellitus and remains a leading cause of vision loss globally. Its aetiology and pathology have been extensively studied for half a century, yet there are disappointingly few therapeutic options. Although some new treatments have been introduced for diabetic macular oedema (DMO) (e.g. intravitreal vascular endothelial growth factor inhibitors ('anti-VEGFs') and new steroids), up to 50% of patients fail to respond. Furthermore, for people with proliferative diabetic retinopathy (PDR), laser photocoagulation remains a mainstay therapy, even though it is an inherently destructive procedure. This review summarises the clinical features of diabetic retinopathy and its risk factors. It describes details of retinal pathology and how advances in our understanding of pathogenesis have led to identification of new therapeutic targets. We emphasise that although there have been significant advances, there is still a pressing need for a better understanding basic mechanisms enable development of reliable and robust means to identify patients at highest risk, and to intervene effectively before vision loss occurs.
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114
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Malaguarnera G, Gagliano C, Salomone S, Giordano M, Bucolo C, Pappalardo A, Drago F, Caraci F, Avitabile T, Motta M. Folate status in type 2 diabetic patients with and without retinopathy. Clin Ophthalmol 2015; 9:1437-42. [PMID: 26300625 PMCID: PMC4536839 DOI: 10.2147/opth.s77538] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Background Folate deficiency is associated with cardiovascular disease, megaloblastic anemia, and with hyperhomocysteinemia. This study has been undertaken to investigate the role of folate status during the progression of the diabetic retinopathy. Methods We measured the plasma levels of homocysteine, folic acid, and red cell folate in 70 diabetic type 2 patients with nonproliferative diabetic retinopathy (NPDR), 65 with proliferative diabetic retinopathy (PDR), 96 without diabetic retinopathy, and 80 healthy subjects used as a control group. Results We found higher plasma levels of homocysteine in the NPDR group compared to the control group (P<0.001) and in the PDR group compared to control group (P<0.001) and NPDR group (P<0.01). The severity of diabetic retinopathy was associated with lower folic acid and red cell folate levels, and a significant difference was observed between PDR and NPDR groups (P<0.05). Conclusion The folate status could play a role in the development and progression of diabetic retinopathy.
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Affiliation(s)
- Giulia Malaguarnera
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Caterina Gagliano
- Department of Ophthalmology, University of Catania, Catania, Italy ; Neurovisual Science Technology (NEST), Catania, Catania, Italy
| | - Salvatore Salomone
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Maria Giordano
- Gerontology and Bone Metabolic Disease Section, Department of Medical Sciences, University of Turin, Turin, Italy
| | - Claudio Bucolo
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | | | - Filippo Drago
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Filippo Caraci
- Department of Drug Sciences, University of Catania, Catania, Italy ; IRCCS Association Oasi Maria S.S.-Institute for Research on Mental Retardation and Brain Aging, Troina, Enna, Italy
| | | | - Massimo Motta
- Department of Medical and Paediatric Sciences, University of Catania, Italy
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Oxidative stress and epigenetic modifications in the pathogenesis of diabetic retinopathy. Prog Retin Eye Res 2015; 48:40-61. [PMID: 25975734 DOI: 10.1016/j.preteyeres.2015.05.001] [Citation(s) in RCA: 222] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 04/29/2015] [Accepted: 05/01/2015] [Indexed: 12/21/2022]
Abstract
Diabetic retinopathy remains the major cause of blindness among working age adults. Although a number of metabolic abnormalities have been associated with its development, due to complex nature of this multi-factorial disease, a link between any specific abnormality and diabetic retinopathy remains largely speculative. Diabetes increases oxidative stress in the retina and its capillary cells, and overwhelming evidence suggests a bidirectional relationship between oxidative stress and other major metabolic abnormalities implicated in the development of diabetic retinopathy. Due to increased production of cytosolic reactive oxygen species, mitochondrial membranes are damaged and their membrane potentials are impaired, and complex III of the electron transport system is compromised. Suboptimal enzymatic and nonenzymatic antioxidant defense system further aids in the accumulation of free radicals. As the duration of the disease progresses, mitochondrial DNA (mtDNA) is damaged and the DNA repair system is compromised, and due to impaired transcription of mtDNA-encoded proteins, the integrity of the electron transport system is encumbered. Due to decreased mtDNA biogenesis and impaired transcription, superoxide accumulation is further increased, and the vicious cycle of free radicals continues to self-propagate. Diabetic milieu also alters enzymes responsible for DNA and histone modifications, and various genes important for mitochondrial homeostasis, including mitochondrial biosynthesis, damage and antioxidant defense, undergo epigenetic modifications. Although antioxidant administration in animal models has yielded encouraging results in preventing diabetic retinopathy, controlled longitudinal human studies remain to be conducted. Furthermore, the role of epigenetic in mitochondrial homeostasis suggests that regulation of such modifications also has potential to inhibit/retard the development of diabetic retinopathy.
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Osorio-Paz I, Uribe-Carvajal S, Salceda R. In the Early Stages of Diabetes, Rat Retinal Mitochondria Undergo Mild Uncoupling due to UCP2 Activity. PLoS One 2015; 10:e0122727. [PMID: 25951172 PMCID: PMC4423783 DOI: 10.1371/journal.pone.0122727] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 02/12/2015] [Indexed: 01/04/2023] Open
Abstract
In order to maintain high transmembrane ionic gradients, retinal tissues require a large amount of energy probably provided by a high rate of both, glycolysis and oxidative phosphorylation. However, little information exists on retinal mitochondrial efficiency. We analyzed the retinal mitochondrial activity in ex vivo retinas and in isolated mitochondria from normal rat retina and from short-term streptozotocin-diabetic rats. In normal ex vivo retinas, increasing glucose concentrations from 5.6mM to 30mM caused a four-fold increase in glucose accumulation and CO2 production. Retina from diabetic rats accumulated similar amounts of glucose. However, CO2 production was not as high. Isolated mitochondria from normal rat retina exhibited a resting rate of oxygen consumption of 14.6 ± 1.1 natgO (min.mg prot)-1 and a respiratory control of 4.0. Mitochondria from 7, 20 and 45 days diabetic rats increased the resting rate of oxygen consumption and the activity of the electron transport complexes; under these conditions the mitochondrial transmembrane potential decreased. In spite of this, the ATP synthesis was not modified. GDP, an UCP2 inhibitor, increased mitochondrial membrane potential and superoxide production in controls and at 45 days of diabetes. The role of UCP2 is discussed. The results suggest that at the early stage of diabetes we studied, retinal mitochondria undergo adaptations leading to maintain energetic requirements and prevent oxidative stress.
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Affiliation(s)
- Ixchel Osorio-Paz
- Departamento de Neurodesarrollo y Fisiología, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México Distrito Federal, México
| | - Salvador Uribe-Carvajal
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México Distrito Federal, México
| | - Rocío Salceda
- Departamento de Neurodesarrollo y Fisiología, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México Distrito Federal, México
- * E-mail:
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Mori A, Takei T, Sakamoto K, Nakahara T, Ishii K. 4-Hydroxy-2-nonenal attenuates β2-adrenoceptor-mediated vasodilation of rat retinal arterioles. Naunyn Schmiedebergs Arch Pharmacol 2015; 388:575-82. [PMID: 25693977 DOI: 10.1007/s00210-015-1099-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Accepted: 02/01/2015] [Indexed: 01/16/2023]
Abstract
4-Hydroxy-2-nonenal (4-HNE) is a major reactive aldehyde formed by lipid peroxidation, and it plays an important role in the pathogenesis of several vascular diseases, including diabetes mellitus. In this study, we examined the effects of 4-HNE on the vasodilatory mechanisms of rat retinal arterioles. The retinal vasodilator responses were assessed by measuring the diameter of retinal arterioles in the fundus images. Intravitreal injection of 4-HNE significantly prevented the vasodilation of retinal arterioles induced by the β2-adrenoceptor agonist salbutamol but not the nitric oxide donor (±)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide (NOR3). Iberiotoxin, an inhibitor of large-conductance KCa (BKCa) channels, significantly reduced the salbutamol-induced vasodilation of retinal arterioles. The vasodilator effect of BMS-191011, a BKCa channel opener, on retinal arterioles was significantly attenuated by 4-HNE. These results suggest that 4-HNE attenuates retinal vasodilator responses to β2-adrenoceptor agonists through the impairment of the BKCa pathway. The direct effect of 4-HNE on retinal blood vessels may, therefore, contribute to the retinal vascular dysfunction observed in patients with diabetes mellitus.
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Affiliation(s)
- Asami Mori
- Department of Molecular Pharmacology, Kitasato University School of Pharmaceutical Sciences, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan
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Gou H, Wen D, Ma C, Li M, Li Y, Zhang W, Liu L, Cong B. Protective effects of cholecystokinin-8 on methamphetamine-induced behavioral changes and dopaminergic neurodegeneration in mice. Behav Brain Res 2015; 283:87-96. [PMID: 25629941 DOI: 10.1016/j.bbr.2015.01.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 01/15/2015] [Accepted: 01/19/2015] [Indexed: 01/15/2023]
Abstract
We investigated whether pretreatment with the neuropeptide cholecystokinin-8 affected methamphetamine (METH)-induced behavioral changes and dopaminergic neurodegeneration in male C57/BL6 mice. CCK-8 pretreatment alone had no effect on locomotion and stereotypic behavior and could not induce behavioral sensitization; however, it attenuated, in a dose-dependent manner, hyperlocomotion and behavioral sensitization induced by a low dose of METH (1mg/kg). CCK-8 attenuated METH-induced stereotypic behavior at a dose of 3mg/kg but not at 10mg/kg. CCK-8 pretreatment attenuated METH (10mg/kg)-induced hyperthermia, the decrease of tyrosine hydroxylase (TH) and dopamine transporter (DAT) in the striatum, and TH in the substantia nigra. CCK-8 alone had no effect on rectal temperature, TH and DAT expression in the nigrostriatal region. In conclusion, our study demonstrated that pretreatment with CCK-8 inhibited changes typically induced by repeated exposure to METH, such as hyperlocomotion, behavioral sensitization, stereotypic behavior, and dopaminergic neurotoxicity. These findings make CCK-8 a potential therapeutic agent for the treatment of multiple symptoms associated with METH abuse.
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Affiliation(s)
- Hongyan Gou
- Department of Forensic Medicine, Hebei Medical University, Hebei Key Laboratory of Forensic Medicine, Shijiazhuang 050017, China
| | - Di Wen
- Department of Forensic Medicine, Hebei Medical University, Hebei Key Laboratory of Forensic Medicine, Shijiazhuang 050017, China
| | - Chunling Ma
- Department of Forensic Medicine, Hebei Medical University, Hebei Key Laboratory of Forensic Medicine, Shijiazhuang 050017, China.
| | - Ming Li
- Department of Forensic Medicine, Hebei Medical University, Hebei Key Laboratory of Forensic Medicine, Shijiazhuang 050017, China
| | - Yingmin Li
- Department of Forensic Medicine, Hebei Medical University, Hebei Key Laboratory of Forensic Medicine, Shijiazhuang 050017, China
| | - Wenfang Zhang
- The 8th Brigade of General Division of Criminal Investigation, Beijing Municipal Public Security Bureau, Beijing 100006, China
| | - Li Liu
- The 8th Brigade of General Division of Criminal Investigation, Beijing Municipal Public Security Bureau, Beijing 100006, China
| | - Bin Cong
- Department of Forensic Medicine, Hebei Medical University, Hebei Key Laboratory of Forensic Medicine, Shijiazhuang 050017, China.
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Primary retinal cultures as a tool for modeling diabetic retinopathy: an overview. BIOMED RESEARCH INTERNATIONAL 2015; 2015:364924. [PMID: 25688355 PMCID: PMC4320900 DOI: 10.1155/2015/364924] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 12/04/2014] [Accepted: 12/23/2014] [Indexed: 12/21/2022]
Abstract
Experimental models of diabetic retinopathy (DR) have had a crucial role in the comprehension of the pathophysiology of the disease and the identification of new therapeutic strategies. Most of these studies have been conducted in vivo, in animal models. However, a significant contribution has also been provided by studies on retinal cultures, especially regarding the effects of the potentially toxic components of the diabetic milieu on retinal cell homeostasis, the characterization of the mechanisms on the basis of retinal damage, and the identification of potentially protective molecules. In this review, we highlight the contribution given by primary retinal cultures to the study of DR, focusing on early neuroglial impairment. We also speculate on possible themes into which studies based on retinal cell cultures could provide deeper insight.
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Sekioka R, Tanaka M, Nishimura T, Itoh H. Low serum total bilirubin concentration in patients with type 1 diabetes mellitus complicated by retinopathy and nephropathy. Diabetol Int 2015. [DOI: 10.1007/s13340-014-0201-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Thiraphatthanavong P, Wattanathorn J, Muchimapura S, Thukham-mee W, Lertrat K, Suriharn B. The combined extract of purple waxy corn and ginger prevents cataractogenesis and retinopathy in streptozotocin-diabetic rats. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2014; 2014:789406. [PMID: 25614778 PMCID: PMC4295599 DOI: 10.1155/2014/789406] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 12/12/2014] [Accepted: 12/14/2014] [Indexed: 12/28/2022]
Abstract
Based on the crucial roles of oxidative stress and aldose reductase on diabetic complications and the protective effect against diabetic eye complication of purple waxy corn and ginger (PWCG) together with the synergistic effect concept, we aimed to determine anticataract and antiretinopathy effects of the combined extract of purple waxy corn and ginger (PWCG). The streptozotocin diabetics with the blood glucose levels >250 mg·dL(-1) were orally given the extract at doses of 50, 100, and 200 mg/kg·BW(-1) for 10 weeks. Then, lens opacity and histopathology of retina were determined. The changes of MDA together with the activities of SOD, CAT, GPx, and AR in lens were also determined using biochemical assays. All doses of PWCG decreased lens opacity, MDA, and AR in the lens of diabetic rats. The elevation of CAT and GPx activities was also observed. The antiretinopathy property of the combined extract was also confirmed by the increased number of neurons in ganglion cell layer and thickness of total retina and retinal nuclear layer in diabetic rats. PWCG is the potential functional food to protect against diabetic cataract and retinopathy. However, further studies concerning toxicity and clinical trial are still essential.
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Affiliation(s)
- Paphaphat Thiraphatthanavong
- Department of Physiology and Graduate School (Neuroscience Program), Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
- Integrative Complementary Alternative Medicine Research and Development Center, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Jintanaporn Wattanathorn
- Integrative Complementary Alternative Medicine Research and Development Center, Khon Kaen University, Khon Kaen 40002, Thailand
- Department of Physiology, Faculty of Medicine, Khon Kaen Unieversity, Khon Kaen 40002, Thailand
| | - Supaporn Muchimapura
- Integrative Complementary Alternative Medicine Research and Development Center, Khon Kaen University, Khon Kaen 40002, Thailand
- Department of Physiology, Faculty of Medicine, Khon Kaen Unieversity, Khon Kaen 40002, Thailand
| | - Wipawee Thukham-mee
- Integrative Complementary Alternative Medicine Research and Development Center, Khon Kaen University, Khon Kaen 40002, Thailand
- Department of Physiology, Faculty of Medicine, Khon Kaen Unieversity, Khon Kaen 40002, Thailand
| | - Kamol Lertrat
- Faculty of Agriculture, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Bhalang Suriharn
- Faculty of Agriculture, Khon Kaen University, Khon Kaen 40002, Thailand
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Current nanotechnology approaches for the treatment and management of diabetic retinopathy. Eur J Pharm Biopharm 2014; 95:307-22. [PMID: 25536109 DOI: 10.1016/j.ejpb.2014.12.023] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 12/08/2014] [Accepted: 12/15/2014] [Indexed: 01/08/2023]
Abstract
Diabetic retinopathy (DR) is a consequence of diabetes mellitus at the ocular level, leading to vision loss, and contributing to the decrease of patient's life quality. The biochemical and anatomic abnormalities that occur in DR are discussed in this review to better understand and manage the development of new therapeutic strategies. The use of new drug delivery systems based on nanoparticles (e.g. liposomes, dendrimers, cationic nanoemulsions, lipid and polymeric nanoparticles) is discussed along with the current traditional treatments, pointing out the advantages of the proposed nanomedicines to target this ocular disease. Despite the multifactorial nature of DR, which is not entirely understood, some strategies based on nanoparticles are being exploited for a more efficient drug delivery to the posterior segment of the eye. On the other hand, the use of some nanoparticles also seems to contribute to the development of DR symptoms (e.g. retinal neovascularization), which are also discussed in light of an efficient management of this ocular chronic disease.
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Abu El-Asrar AM, Mohammad G, Nawaz MI, Siddiquei MM. High-Mobility Group Box-1 Modulates the Expression of Inflammatory and Angiogenic Signaling Pathways in Diabetic Retina. Curr Eye Res 2014; 40:1141-52. [PMID: 25495026 DOI: 10.3109/02713683.2014.982829] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
PURPOSE The expression of high-mobility group box-1 (HMGB1) is upregulated in epiretinal membranes and vitreous fluid from patients with proliferative diabetic retinopathy and in the diabetic retina. HMGB1 mediates inflammation, breakdown of the blood-retinal barrier and apoptosis in the diabetic retina. Here, we investigated inflammatory and angiogenic signaling pathways activated by HMGB1 in diabetic retina. METHODS Human retinal microvascular endothelial cells (HRMEC) and retinas from 1-month diabetic rats and normal rats intravitreally injected with HMGB1 were studied using RT-PCR, Western blot analysis and co-immunoprecipitation. We also studied the effect of the HMGB1 inhibitor glycyrrhizin on diabetes-induced biochemical changes in the retina. RESULTS Diabetes and intravitreal injection of HMGB1 in normal rats induced significant upregulation of the mRNA levels of the chemokine stromal cell-derived factor-1 (SDF-1/CXCL12) receptor CXCR4 and protein levels of hypoxia-inducible factor-1α, early growth response-1, tyrosine kinase 2 and the CXCL12/CXCR4 chemokine axis. Constant glycyrrhizin intake from onset of diabetes did not affect the metabolic status of the diabetic rats, but it restored these increased mediators to control values. Stimulation of HRMEC with HMGB1 and intraviteral injection of HMGB1 significantly increased the expression of vascular endothelial growth factor (VEGF) and VEGF receptor-2. Co-immunoprecipitation studies showed that diabetes increased the interaction between CXCL12 and CXCR4 and between HMGB1 and receptor for advanced glycation end products (RAGE), but not between HMGB1 and the CXCL12/CXCR4 chemokine axis. CONCLUSIONS Our findings suggest that HMGB1 activates inflammatory and angiogenic signaling pathways in diabetic retina mediated by RAGE.
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Affiliation(s)
- Ahmed M Abu El-Asrar
- a Department of Ophthalmology , College of Medicine, King Saud University, King Abdulaziz University Hospital , Riyadh , Saudi Arabia
| | - Ghulam Mohammad
- a Department of Ophthalmology , College of Medicine, King Saud University, King Abdulaziz University Hospital , Riyadh , Saudi Arabia
| | - Mohammad Imtiaz Nawaz
- a Department of Ophthalmology , College of Medicine, King Saud University, King Abdulaziz University Hospital , Riyadh , Saudi Arabia
| | - Mohammad Mairaj Siddiquei
- a Department of Ophthalmology , College of Medicine, King Saud University, King Abdulaziz University Hospital , Riyadh , Saudi Arabia
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Neudorfer M, Kessner R, Goldenberg D, Lavie A, Kessler A. Retrobulbar blood flow changes in eyes with diabetic retinopathy: a 10-year follow-up study. Clin Ophthalmol 2014; 8:2325-32. [PMID: 25473257 PMCID: PMC4247149 DOI: 10.2147/opth.s71158] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Purpose We sought to assess long-term changes in the flow parameters of retrobulbar vessels in diabetic patients. Methods The retrobulbar circulation of 138 eyes was evaluated between 1994 and 1995 and 36 eyes were reevaluated between 2004 and 2008 (study group). They were divided into four groups: eyes of diabetic patients without diabetic retinopathy (DR), eyes with nonproliferative DR, eyes with proliferative DR, and eyes of nondiabetic patients (controls). Color Doppler imaging was used to assess the flow velocities in the major retrobulbar vessels. The resistive index (RI) was calculated and compared among the groups and between the two time periods. Results RI values of the central retinal artery and posterior ciliary artery had increased in the two non-DR groups and in the nonproliferative DR group, with a surprising decrease measured in eyes with proliferative DR (P= nonsignificant [NS]). Combining the nonproliferative DR and proliferative DR groups resulted in a milder increase of the RI of the posterior ciliary artery (P= NS) and the central retinal artery (P=0.02) in the DR group compared to the other groups. Conclusion Our results demonstrate that an increase of the resistance in the retrobulbar vessels, as a part of DR, can lessen over time and may even be reversed.
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Affiliation(s)
- Meira Neudorfer
- Department of Ophthalmology, Sackler Faculty of Medicine, Tel Aviv Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel
| | - Rivka Kessner
- Department of Ophthalmology, Sackler Faculty of Medicine, Tel Aviv Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel
| | - Dafna Goldenberg
- Department of Ophthalmology, Sackler Faculty of Medicine, Tel Aviv Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel
| | - Anat Lavie
- Department of Ophthalmology, Sackler Faculty of Medicine, Tel Aviv Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel
| | - Ada Kessler
- Radiology Ultrasound Unit, Sackler Faculty of Medicine, Tel Aviv Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel
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Protective effects of astragaloside IV on db/db mice with diabetic retinopathy. PLoS One 2014; 9:e112207. [PMID: 25411784 PMCID: PMC4239035 DOI: 10.1371/journal.pone.0112207] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 10/10/2014] [Indexed: 10/31/2022] Open
Abstract
OBJECTIVES Diabetic retinopathy (DR) is a common diabetic eye disease which is well-known as the result of microvascular retinal changes. Although the potential biological functions of astragaloside IV (AS IV) have long been described in traditional system of medicine, its protective effect on DR remains unclear. This study aims to investigate the function and mechanism of AS IV on type 2 diabetic db/db mice. METHODS Db/db mice were treated with AS IV (4.5 mg/kg or 9 mg/kg) or physiological saline by oral gavage for 20 weeks along with db/m mice. In each group, retinal ganglion cell (RGC) function was measured by pattern electroretinogram (ERG) and apoptosis was determined by Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. Blood and retina aldose reductase (AR) activity were quantified by chemiluminescence analysis. The expressions of phosporylated-ERK1/2, NF-κB were determined by Western blot analysis. Furthermore, the expression of related downstream proteins were quantified by Label-based Mouse Antibody Array. RESULTS Administration of AS IV significantly improved the amplitude in pattern ERG and reduced the apoptosis of RGCs.in db/db mice. Furthermore, downregulation of AR activity, ERK1/2 phosphorylation, NF-κB and related cytokine were observed in AS IV treatment group. CONCLUSIONS Our study indicated that AS IV, as an inhibitor of AR, could prevent the activation of ERK1/2 phosporylation and NF-kB and further relieve the RGCs disfunction in db/db mice with DR. It has provided a basis for investigating the clinical efficacy of AR inhibitors in preventing DR.
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Abstract
The aim of the study was to investigate the association between lipid peroxidation and antioxidant status in nonobese type 2 diabetes mellitus (T2DM) and further to correlate whether their significant association is putatively associated with the pathogenesis of T2DM. A number of 102 nonobese T2DM subjects and 95 nondiabetic subjects as healthy controls were enrolled in this cross-sectional study. Serum samples were collected in cryovials for malondialdehyde (MDA) and thiol assays. Total thiol or sulfhydryl (–SH) groups in peripheral blood mononuclear cells (PBMCs) and sera, as well as level of MDA, a marker for lipid peroxidation in serum, were measured spectrophotometrically. Serum MDA level was found significantly higher whereas serum and PBMC total thiol levels were diminished significantly among nonobese T2DM subjects compared to HC subjects. Moreover, serum MDA level is found to have a significant inverse correlation with serum total thiol and PBMC thiol levels among DM subjects, but no significant correlation was observed in HC individuals. A significant inverse correlation between serum MDA and serum total thiol levels among nonobese T2DM subjects suggests a close association of increased oxidative stress with decreased antioxidant status in nonobese T2DM.
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Oxidative stress induces endothelial cell senescence via downregulation of Sirt6. BIOMED RESEARCH INTERNATIONAL 2014; 2014:902842. [PMID: 25162034 PMCID: PMC4138737 DOI: 10.1155/2014/902842] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2014] [Accepted: 07/13/2014] [Indexed: 01/19/2023]
Abstract
Accumulating evidence has shown that diabetes accelerates aging and endothelial cell senescence is involved in the pathogenesis of diabetic vascular complications, including diabetic retinopathy. Oxidative stress is recognized as a key factor in the induction of endothelial senescence and diabetic retinopathy. However, specific mechanisms involved in oxidative stress-induced endothelial senescence have not been elucidated. We hypothesized that Sirt6, which is a nuclear, chromatin-bound protein critically involved in many pathophysiologic processes such as aging and inflammation, may have a role in oxidative stress-induced vascular cell senescence. Measurement of Sirt6 expression in human endothelial cells revealed that H2O2 treatment significantly reduced Sirt6 protein. The loss of Sirt6 was associated with an induction of a senescence phenotype in endothelial cells, including decreased cell growth, proliferation and angiogenic ability, and increased expression of senescence-associated β-galactosidase activity. Additionally, H2O2 treatment reduced eNOS expression, enhanced p21 expression, and dephosphorylated (activated) retinoblastoma (Rb) protein. All of these alternations were attenuated by overexpression of Sirt6, while partial knockdown of Sirt6 expression by siRNA mimicked the effect of H2O2. In conclusion, these results suggest that Sirt6 is a critical regulator of endothelial senescence and oxidative stress-induced downregulation of Sirt6 is likely involved in the pathogenesis of diabetic retinopathy.
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Moran E, Ding L, Wang Z, Cheng R, Chen Q, Moore R, Takahashi Y, Ma JX. Protective and antioxidant effects of PPARα in the ischemic retina. Invest Ophthalmol Vis Sci 2014; 55:4568-76. [PMID: 24825105 DOI: 10.1167/iovs.13-13127] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Previous studies have demonstrated that peroxisome proliferator-activated receptor-alpha (PPARα) agonists have therapeutic effects in diabetic retinopathy, although the mechanism of action remains incompletely understood. The purpose of this study was to evaluate PPARα's protective effects in the ischemic retina, and to delineate its molecular mechanism of action. METHODS For the oxygen-induced retinopathy (OIR) model, wild-type (WT), and PPARα knockout (PPARα(-/-)) mice were exposed to 75% O₂ from postnatal day 7 (P7) to P12 and treated with the PPARα agonist fenofibric acid (Feno-FA) from P12 to P16. At P17, the effects of Feno-FA on retinal glial fibrillary acidic protein (GFAP) expression, apoptotic DNA cleavage, and TUNEL labeling were analyzed. Cultured retinal cells were exposed to CoCl₂ to induce hypoxia, and TUNEL staining and 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein dye were used to measure apoptosis and reactive oxygen species (ROS) generation. Western blotting was used to measure GFAP levels and cell signaling. RESULTS Feno-FA decreased retinal apoptosis and oxidative stress in WT but not PPARα(-/-) OIR mice. Peroxisome proliferator-activated receptor-alpha knockout OIR mice showed increased retinal cell death and glial activation in comparison to WT OIR mice. Feno-FA treatment and PPARα overexpression protected cultured retinal cells from hypoxic cell death and decreased ROS levels. Nuclear hypoxia-inducible factor-α (HIF-1α) and nicotine adenine dinucleotide phosphate oxidase-4 (Nox 4) were increased in OIR retinas and downregulated by Feno-FA in WT but not in PPARα(-/-) mice. CONCLUSIONS Peroxisome proliferator-activated receptor-alpha has a potent antiapoptotic effect in the ischemic retina. This protective effect may be mediated in part through downregulation of HIF-1α/Nox 4 and consequently alleviation of oxidative stress.
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Affiliation(s)
- Elizabeth Moran
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Lexi Ding
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, China
| | - Zhongxiao Wang
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Rui Cheng
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Qian Chen
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Robert Moore
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Yusuke Takahashi
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Jian-xing Ma
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
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131
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Eshaq RS, Wright WS, Harris NR. Oxygen delivery, consumption, and conversion to reactive oxygen species in experimental models of diabetic retinopathy. Redox Biol 2014; 2:661-6. [PMID: 24936440 PMCID: PMC4052533 DOI: 10.1016/j.redox.2014.04.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 04/15/2014] [Accepted: 04/16/2014] [Indexed: 11/30/2022] Open
Abstract
Retinal tissue receives its supply of oxygen from two sources – the retinal and choroidal circulations. Decreases in retinal blood flow occur in the early stages of diabetes, with the eventual development of hypoxia thought to contribute to pathological neovascularization. Oxygen consumption in the retina has been found to decrease in diabetes, possibly due to either a reduction in neuronal metabolism or to cell death. Diabetes also enhances the rate of conversion of oxygen to superoxide in the retina, with experimental evidence suggesting that mitochondrial superoxide not only drives the overall production of reactive oxygen species, but also initiates several pathways leading to retinopathy, including the increased activity of the polyol and hexosamine pathways, increased production of advanced glycation end products and expression of their receptors, and activation of protein kinase C. Diabetes alters oxygen delivery and consumption in the retina. Conversion of oxygen to superoxide increases in the diabetic retina. An initial production of mitochondrial superoxide generates further ROS. ROS have been found to mediate deleterious pathways in the diabetic retina.
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Affiliation(s)
- Randa S Eshaq
- Department of Molecular & Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - William S Wright
- Department of Biomedical Sciences, University of South Carolina School of Medicine, Greenville, SC, USA
| | - Norman R Harris
- Department of Molecular & Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA
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Mukai N, Yasuda M, Ninomiya T, Hata J, Hirakawa Y, Ikeda F, Fukuhara M, Hotta T, Koga M, Nakamura U, Kang D, Kitazono T, Kiyohara Y. Thresholds of various glycemic measures for diagnosing diabetes based on prevalence of retinopathy in community-dwelling Japanese subjects: the Hisayama Study. Cardiovasc Diabetol 2014; 13:45. [PMID: 24533962 PMCID: PMC3936993 DOI: 10.1186/1475-2840-13-45] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 02/12/2014] [Indexed: 02/07/2023] Open
Abstract
Background There has been controversy over the diagnostic thresholds of hemoglobin A1c (HbA1c) for diabetes. In addition, no study has examined the thresholds of glycated albumin (GA) and 1,5-anhydroglucitol (1,5-AG) for diagnosing diabetes using the presence of diabetic retinopathy (DR). We examined the optimal thresholds of various glycemic measures for diagnosing diabetes based on the prevalence of DR in community-dwelling Japanese subjects. Methods A total of 2,681 subjects aged 40-79 years underwent a 75-g oral glucose tolerance test, measurement of HbA1c, GA, and 1,5-AG, and an ophthalmic examination in 2007-2008. The associations of glycemic measures with DR status were examined cross-sectionally. DR was assessed by an examination of the fundus photograph of each eye and graded according to the International Clinical Diabetic Retinopathy Disease Severity Scale. We divided the values of glycemic measures into ten groups on the basis of deciles. The receiver operating characteristic (ROC) curve analysis was performed to determine the optimal threshold of each glycemic measure for detecting the presence of DR. Results Of the subjects, 52 had DR. The prevalence of DR increased steeply above the ninth decile for fasting plasma glucose (FPG) (6.2-6.8 mmol/l), for 2-hour postload glucose (PG) (9.2-12.4 mmol/l), for HbA1c (5.9-6.2% [41-44 mmol/mol]), and for GA (16.2-17.5%), and below the second decile for 1,5-AG (9.6-13.5 μg/mL). The ROC curve analysis showed that the optimal thresholds for DR were 6.5 mmol/l for FPG, 11.5 mmol/l for 2-hour PG, 6.1% (43 mmol/mol) for HbA1c, 17.0% for GA, and 12.1 μg/mL for 1,5-AG. The area under the ROC curve (AUC) for 2-hour PG (0.947) was significantly larger than that for FPG (0.908), GA (0.906), and 1,5-AG (0.881), and was marginally significantly higher than that for HbA1c (0.919). The AUCs for FPG, HbA1c, GA, and 1,5-AG were not significantly different. Conclusions Our findings suggest that the FPG and HbA1c thresholds for diagnosing diabetes in the Japanese population are lower than the current diagnostic criterion, while the 2-hour PG threshold is comparable with the diagnostic criterion. 2-hour PG had the highest discriminative ability, whereas FPG, HbA1c, GA, and 1,5-AG were similar in their ability.
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Affiliation(s)
- Naoko Mukai
- Department of Environmental Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
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Antioxidant drug therapy approaches for neuroprotection in chronic diseases of the retina. Int J Mol Sci 2014; 15:1865-86. [PMID: 24473138 PMCID: PMC3958826 DOI: 10.3390/ijms15021865] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 01/18/2014] [Accepted: 01/21/2014] [Indexed: 12/31/2022] Open
Abstract
The molecular pathways contributing to visual signal transduction in the retina generate a high energy demand that has functional and structural consequences such as vascularization and high metabolic rates contributing to oxidative stress. Multiple signaling cascades are involved to actively regulate the redox state of the retina. Age-related processes increase the oxidative load, resulting in chronically elevated levels of oxidative stress and reactive oxygen species, which in the retina ultimately result in pathologies such as glaucoma or age-related macular degeneration, as well as the neuropathic complications of diabetes in the eye. Specifically, oxidative stress results in deleterious changes to the retina through dysregulation of its intracellular physiology, ultimately leading to neurodegenerative and potentially also vascular dysfunction. Herein we will review the evidence for oxidative stress-induced contributions to each of the three major ocular pathologies, glaucoma, age-related macular degeneration, and diabetic retinopathy. The premise for neuroprotective strategies for these ocular disorders will be discussed in the context of recent clinical and preclinical research pursuing novel therapy development approaches.
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134
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Hu B, Zhang Y, Zeng Q, Han Q, Zhang L, Liu M, Li X. Intravitreal injection of ranibizumab and CTGF shRNA improves retinal gene expression and microvessel ultrastructure in a rodent model of diabetes. Int J Mol Sci 2014; 15:1606-24. [PMID: 24451141 PMCID: PMC3907889 DOI: 10.3390/ijms15011606] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 01/10/2014] [Accepted: 01/13/2014] [Indexed: 01/11/2023] Open
Abstract
Therapeutic modalities targeting vascular endothelial growth factor (VEGF) have been used to treat neovascularization and macular edema. However, anti-VEGF treatment alone may cause up-regulation of connective tissue growth factor (CTGF) in the retina, increasing the risk of fibrosis and tractional retinal detachment. Therefore, in this study, we employ a novel dual-target intervention that involves intravitreal injection of the VEGF inhibitor ranibizumab and a transfection reagent-treated non-viral vector carrying anti-CTGF short hairpin RNA (shRNA) driven by human RNA polymerase III promoter U6. The effects of the dual-target intervention on the expression of VEGF and CTGF and on microvessel ultrastructure were examined in retina of streptozocin-induced diabetic rats. CTGF was significantly up-regulated at week 8 after diabetic induction, whereas VEGF was not up-regulated until week 10. The high expression of both genes was maintained at week 12. Transmission electron microscopy also revealed progressive exacerbation of microvessel ultrastructure during the same period. In addition, ranibizumab significantly lowered VEGF but elevated CTGF mRNA, whereas CTGF shRNA significantly reduced the mRNA levels of both CTGF and VEGF in diabetic retinas. Importantly, dual-target intervention normalized the transcript levels of both target genes and ameliorated retinal microvessel ultrastructural damage better than either single-target intervention. These results suggest the advantages of dual-target over single-target interventions in diabetic retina and reveal a novel therapeutic modality for diabetic retinopathy.
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MESH Headings
- Animals
- Antibodies, Monoclonal, Humanized/administration & dosage
- Antibodies, Monoclonal, Humanized/pharmacology
- Antibodies, Monoclonal, Humanized/therapeutic use
- Connective Tissue Growth Factor/genetics
- Connective Tissue Growth Factor/metabolism
- Diabetes Mellitus, Experimental/drug therapy
- Diabetes Mellitus, Experimental/metabolism
- Diabetic Retinopathy/drug therapy
- Diabetic Retinopathy/metabolism
- HEK293 Cells
- Humans
- Injections, Intraocular
- Male
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Small Interfering/genetics
- Ranibizumab
- Rats
- Rats, Sprague-Dawley
- Retina/drug effects
- Retina/metabolism
- Retina/ultrastructure
- Retinal Vessels/drug effects
- Retinal Vessels/metabolism
- Retinal Vessels/ultrastructure
- Vascular Endothelial Growth Factor A/genetics
- Vascular Endothelial Growth Factor A/metabolism
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Affiliation(s)
- Bojie Hu
- Tianjin Medical University Eye Hospital/Eye Institute, Fukang Rd. 251#, Nankai Dist., Tianjin 300384, China.
| | - Yan Zhang
- Tianjin Medical University Eye Hospital/Eye Institute, Fukang Rd. 251#, Nankai Dist., Tianjin 300384, China.
| | - Qing Zeng
- Tianjin Medical University Eye Hospital/Eye Institute, Fukang Rd. 251#, Nankai Dist., Tianjin 300384, China.
| | - Qian Han
- Tianjin Medical University Eye Hospital/Eye Institute, Fukang Rd. 251#, Nankai Dist., Tianjin 300384, China.
| | - Lijuan Zhang
- Tianjin Medical University Eye Hospital/Eye Institute, Fukang Rd. 251#, Nankai Dist., Tianjin 300384, China.
| | - Mian Liu
- Tianjin Medical University Eye Hospital/Eye Institute, Fukang Rd. 251#, Nankai Dist., Tianjin 300384, China.
| | - Xiaorong Li
- Tianjin Medical University Eye Hospital/Eye Institute, Fukang Rd. 251#, Nankai Dist., Tianjin 300384, China.
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Abu El-Asrar AM, Al-Mezaine HS, Ola MS. Pathophysiology and management of diabetic retinopathy. EXPERT REVIEW OF OPHTHALMOLOGY 2014. [DOI: 10.1586/eop.09.52] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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136
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Bhat M, Pouliot M, Couture R, Vaucher E. The kallikrein-kinin system in diabetic retinopathy. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 2014; 69:111-43. [PMID: 25130041 DOI: 10.1007/978-3-319-06683-7_5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Diabetic retinopathy (DR) is a major microvascular complication associated with type 1 and type 2 diabetes mellitus, which can lead to visual impairment and blindness. Current treatment strategies for DR are mostly limited to laser therapies, steroids, and anti-VEGF agents, which are often associated with unwanted side effects leading to further complications. Recent evidence suggests that kinins play a primary role in the development of DR through enhanced vascular permeability, leukocytes infiltration, and other inflammatory mechanisms. These deleterious effects are mediated by kinin B1 and B2 receptors, which are expressed in diabetic human and rodent retina. Importantly, kinin B1 receptor is virtually absent in sane tissue, yet it is induced and upregulated in diabetic retina. These peptides belong to the kallikrein-kinin system (KKS), which contains two separate and independent pathways of regulated serine proteases, namely plasma kallikrein (PK) and tissue kallikrein (TK) that are involved in the biosynthesis of bradykinin (BK) and kallidin (Lys-BK), respectively. Hence, ocular inhibition of kallikreins or antagonism of kinin receptors offers new therapeutic avenues in the treatment and management of DR. Herein, we present an overview of the principal features and known inflammatory mechanisms associated with DR along with the current therapeutic approaches and put special emphasis on the KKS as a new and promising therapeutic target due to its link with key pathways directly associated with the development of DR.
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Mashitani T, Hayashino Y, Okamura S, Tsujii S, Ishii H. Correlations between serum bilirubin levels and diabetic nephropathy progression among Japanese type 2 diabetic patients: a prospective cohort study (Diabetes Distress and Care Registry at Tenri [DDCRT 5]). Diabetes Care 2014; 37:252-8. [PMID: 24009299 DOI: 10.2337/dc13-0407] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To assess the correlations between serum bilirubin levels and diabetic nephropathy development and progression in type 2 diabetic patients. RESEARCH DESIGN AND METHODS Longitudinal data were obtained from 2,511 type 2 diabetic patients registered in a Japanese diabetes registry. To assess the independent correlations between serum bilirubin levels and either the development or progression of diabetic nephropathy, we used logistic regression analysis adjusted for potential confounders. RESULTS The median follow-up period was 503.4 days (range 238-777). The mean patient age, BMI, and HbA1c level was 65.2 years, 24.7 kg/m(2), and 7.5% (58.5 mmol/mol), respectively. Baseline serum bilirubin levels were significantly associated with the urinary albumin-creatinine ratio at baseline (P < 0.001) and 1 year after registration (P < 0.001). Multivariable adjusted odds ratios for progression from microalbuminuria to macroalbuminuria for the second, third, and fourth quartile of serum bilirubin levels were 0.89 (95% CI 0.49-1.58), 0.93 (0.47-1.83), and 0.33 (0.13-0.84), respectively, showing a statistically significant linear trend across categories (P = 0.032). However, this trend disappeared after adjustment for hemoglobin levels. CONCLUSIONS Serum bilirubin levels were associated with diabetic nephropathy progression in type 2 diabetic patients independent of possible confounders. Serum bilirubin levels might be the link in the correlation between hemoglobin levels and nephropathy progression.
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138
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Simplified system to investigate alteration of retinal neurons in diabetes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 801:139-43. [PMID: 24664691 DOI: 10.1007/978-1-4614-3209-8_18] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Diabetic retinopathy (DR) is traditionally considered as a microvascular complication in diabetic retinas. Emerging evidences suggest that the alteration of neuronal function and the death of retinal neurons are part of DR pathology. However, surprisingly little is known about how retinal neurons behave in DR. As diabetic animals are chronicle models that are difficult and expensive to maintain, we used a chemical hypoxia model that mimics the later stage of diabetes and investigated its potential in predicting retinal cell behaviors in diabetes in an efficient manner. In this chapter, we discuss the similarities and differences between diabetic and hypoxic models and the usefulness and limitation of the cobalt-chloride-generated hypoxia system in mice for studying retinal neurobiology in diabetes.
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139
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Njie-Mbye YF, Kulkarni-Chitnis M, Opere CA, Barrett A, Ohia SE. Lipid peroxidation: pathophysiological and pharmacological implications in the eye. Front Physiol 2013; 4:366. [PMID: 24379787 PMCID: PMC3863722 DOI: 10.3389/fphys.2013.00366] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 11/25/2013] [Indexed: 01/17/2023] Open
Abstract
Oxygen-derived free radicals such as hydroxyl and hydroperoxyl species have been shown to oxidize phospholipids and other membrane lipid components leading to lipid peroxidation. In the eye, lipid peroxidation has been reported to play an important role in degenerative ocular diseases (age-related macular degeneration, cataract, glaucoma, diabetic retinopathy). Indeed, ocular tissues are prone to damage from reactive oxygen species due to stress from constant exposure of the eye to sunlight, atmospheric oxygen and environmental chemicals. Furthermore, free radical catalyzed peroxidation of long chain polyunsaturated acids (LCPUFAs) such as arachidonic acid and docosahexaenoic acid leads to generation of LCPUFA metabolites including isoprostanes and neuroprostanes that may further exert pharmacological/toxicological actions in ocular tissues. Evidence from literature supports the presence of endogenous defense mechanisms against reactive oxygen species in the eye, thereby presenting new avenues for the prevention and treatment of ocular degeneration. Hydrogen peroxide (H2O2) and synthetic peroxides can exert pharmacological and toxicological effects on tissues of the anterior uvea of several mammalian species. There is evidence suggesting that the retina, especially retinal ganglion cells can exhibit unique characteristics of antioxidant defense mechanisms. In the posterior segment of the eye, H2O2 and synthetic peroxides produce an inhibitory action on glutamate release (using [(3)H]-D-aspartate as a marker), in vitro and on the endogenous glutamate and glycine concentrations in vivo. In addition to peroxides, isoprostanes can elicit both excitatory and inhibitory effects on norepinephrine (NE) release from sympathetic nerves in isolated mammalian iris ciliary bodies. Whereas isoprostanes attenuate dopamine release from mammalian neural retina, in vitro, these novel arachidonic acid metabolites exhibit a biphasic regulatory effect on glutamate release from retina and can regulate amino acid neurotransmitter metabolism without inducing cell death in the retina. Furthermore, there appears to be an inhibitory role for neuroprostanes in the release of excitatory amino acid neurotransmitters in mammalian retina. The ability of peroxides and metabolites of LCPUFA to alter the integrity of neurotransmitter pools provides new potential target sites and pathways for the treatment of degenerative ocular diseases.
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Affiliation(s)
- Ya Fatou Njie-Mbye
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University Houston, TX, USA
| | - Madhura Kulkarni-Chitnis
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University Houston, TX, USA
| | - Catherine A Opere
- Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Creighton University Omaha, NE, USA
| | - Aaron Barrett
- Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Creighton University Omaha, NE, USA
| | - Sunny E Ohia
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University Houston, TX, USA
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140
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Grover AK, Samson SE. Antioxidants and vision health: facts and fiction. Mol Cell Biochem 2013; 388:173-83. [PMID: 24311110 DOI: 10.1007/s11010-013-1908-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Accepted: 11/15/2013] [Indexed: 12/12/2022]
Abstract
A number of nutritional supplements containing antioxidants are advertised for better vision health. Do they benefit the average consumer? The literature was examined for the effectiveness of antioxidants for human eye health, and for the intricacies in collection of such evidence. The following diseases were considered: cataract, glaucoma, age-related macular degeneration (AMD), retinopathy, retinitis pigmentosa, eye infections, and uveitis. The literature indicates that antioxidant supplements plus lutein have a reasonable probability of retarding AMD. For glaucoma, such supplements were ineffectual in some studies but useful in others. In some studies, antioxidant rich fruits and vegetables were also useful for protection against glaucoma. For diabetic retinopathy, antioxidant supplements may have a small benefit, if any, but only as an adjunct to glycemic control. In very high-risk premature retinopathy and retinitis pigmentosa, antioxidant supplements may be beneficial but those with excess Vitamin E should be avoided. For cataract, there is no evidence for an advantage of such nutritional supplements. However, lubricant drops containing N-acetylcarnosine may be helpful in initial stages of the disease. For eye infections and other causes of uveitis, antioxidants have not been found useful. We recommend that a diet high in antioxidant rich foods should be developed as a habit from an early age. However, when initial signs of vision health deterioration are observed, the appropriate nutritional supplement products may be recommended but only to augment the primary medical treatments.
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Affiliation(s)
- Ashok K Grover
- Department of Medicine, McMaster University, Hamilton, ON, L8N3Z5, Canada,
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Effects of Trigonella foenum-graecum (L.) on retinal oxidative stress, and proinflammatory and angiogenic molecular biomarkers in streptozotocin-induced diabetic rats. Mol Cell Biochem 2013; 388:1-9. [PMID: 24242137 DOI: 10.1007/s11010-013-1893-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Accepted: 11/05/2013] [Indexed: 12/18/2022]
Abstract
The aim of the present study was to investigate the protective effects of Trigonella foenum-graecum Linn. (fenugreek) in Streptozotocin-induced diabetic rat retina. Fenugreek (100 and 200 mg/kg body weights) treatment was carried out for 24 weeks and evaluated for inflammatory [tumor necrosis factor (TNF)-α and interleukin (IL)-1β] and angiogenic [vascular endothelial growth factor (VEGF) and protein kinase C (PKC)-β] molecular biomarkers. Retinal oxidative stress was evaluated by estimating antioxidant (Glutathione, Superoxide dismutase, and Catalase) parameters. Fluorescein angiography was performed to detect retinal vascular leakage. Electron microscopy was performed to determine basement membrane thickness. In the present study, significant rises in the expressions of retinal inflammatory (TNF-α and IL-1β) and angiogenic (VEGF and PKC-β) molecular biomarkers were observed in diabetic retinae compared with normal retinae. However, fenugreek-treated retinae showed marked inhibition in the expression of inflammatory and angiogenic molecular biomarkers. Moreover, results from the present study showed positive modulatory effects of fenugreek on retinal oxidative stress. Fluorescein angiograms and fundus photographs obtained from diabetic retinae showed retinal vascular leakage. On the other hand, fenugreek-treated retinae did not show vascular leakage. Further, thickened BM was recorded in diabetic retina compared with normal retinae. However, fenugreek-treated retinae showed relatively lesser thickening of capillary BM. In conclusion, it may be postulated that fenugreek has great potential in preventing diabetes-induced retinal degeneration in humans after regular consumption in the specified dosage.
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142
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Epigenetic modifications and diabetic retinopathy. BIOMED RESEARCH INTERNATIONAL 2013; 2013:635284. [PMID: 24286082 PMCID: PMC3826295 DOI: 10.1155/2013/635284] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 07/15/2013] [Indexed: 12/20/2022]
Abstract
Diabetic retinopathy remains one of the most debilitating chronic complications, but despite extensive research in the field, the exact mechanism(s) responsible for how retina is damaged in diabetes remains ambiguous. Many metabolic pathways have been implicated in its development, and genes associated with these pathways are altered. Diabetic environment also facilitates epigenetics modifications, which can alter the gene expression without permanent changes in DNA sequence. The role of epigenetics in diabetic retinopathy is now an emerging area, and recent work has shown that genes encoding mitochondrial superoxide dismutase (Sod2) and matrix metalloproteinase-9 (MMP-9) are epigenetically modified, activates of epigenetic modification enzymes, histone lysine demethylase 1 (LSD1), and DNA methyltransferase are increased, and the micro RNAs responsible for regulating nuclear transcriptional factor and VEGF are upregulated. With the growing evidence of epigenetic modifications in diabetic retinopathy, better understanding of these modifications has potential to identify novel targets to inhibit this devastating disease. Fortunately, the inhibitors and mimics targeted towards histone modification, DNA methylation, and miRNAs are now being tried for cancer and other chronic diseases, and better understanding of the role of epigenetics in diabetic retinopathy will open the door for their possible use in combating this blinding disease.
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143
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Albarracin R, Natoli R, Rutar M, Valter K, Provis J. 670 nm light mitigates oxygen-induced degeneration in C57BL/6J mouse retina. BMC Neurosci 2013; 14:125. [PMID: 24134095 PMCID: PMC4015810 DOI: 10.1186/1471-2202-14-125] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Accepted: 09/18/2013] [Indexed: 11/17/2022] Open
Abstract
Background Irradiation with light wavelengths from the far red (FR) to the near infrared (NIR) spectrum (600 nm -1000 nm) has been shown to have beneficial effects in several disease models. In this study, we aim to examine whether 670 nm red light pretreatment can provide protection against hyperoxia-induced damage in the C57BL/6J mouse retina. Adult mice (90–110 days) were pretreated with 9 J/cm2 of 670 nm light once daily for 5 consecutive days prior to being placed in hyperoxic environment (75% oxygen). Control groups were exposed to hyperoxia, but received no 670 nm light pretreatment. Retinas were collected after 0, 3, 7, 10 or 14 days of hyperoxia exposure (n = 12/group) and prepared either for histological analysis, or RNA extraction and quantitative polymerase chain reaction (qPCR). Photoreceptor damage and loss were quantified by counting photoreceptors undergoing cell death and measuring photoreceptor layer thickness. Localization of acrolein, and cytochrome c oxidase subunit Va (Cox Va) were identified through immunohistochemistry. Expression of heme oxygenase-1 (Hmox-1), complement component 3 (C3) and fibroblast growth factor 2 (Fgf-2) genes were quantified using qPCR. Results The hyperoxia-induced photoreceptor loss was accompanied by reduction of metabolic marker, Cox Va, and increased expression of oxidative stress indicator, acrolein and Hmox-1. Pretreatment with 670 nm red light reduced expression of markers of oxidative stress and C3, and slowed, but did not prevent, photoreceptor loss over the time course of hyperoxia exposure. Conclusion The damaging effects of hyperoxia on photoreceptors were ameliorated following pretreatment with 670 nm light in hyperoxic mouse retinas. These results suggest that pretreatment with 670 nm light may provide stability to photoreceptors in conditions of oxidative stress.
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Affiliation(s)
- Rizalyn Albarracin
- ARC Centre of Excellence in Vision Science and John Curtin School of Medical Research, 131 Garran Road, Canberra, ACT 0200, Australia.
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Ergin V, Hariry RE, Karasu C. Carbonyl stress in aging process: role of vitamins and phytochemicals as redox regulators. Aging Dis 2013; 4:276-94. [PMID: 24124633 DOI: 10.14336/ad.2013.0400276] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 08/01/2013] [Accepted: 08/02/2013] [Indexed: 12/15/2022] Open
Abstract
There is a growing scientific agreement that the cellular redox regulators such as antioxidants, particularly the natural polyphenolic forms, may help lower the incidence of some pathologies, including metabolic diseases like diabetes and diabesity, cardiovascular and neurodegenerative abnormalities, and certain cancers or even have anti-aging properties. The recent researches indicate that the degree of metabolic modulation and adaptation response of cells to reductants as well as oxidants establish their survival and homeostasis, which is linked with very critical balance in imbalances in cellular redox capacity and signaling, and that might be an answer the questions why some antioxidants or phytochemicals potentially could do more harm than good, or why some proteins lose their function by increase interactions with glyco- and lipo-oxidation mediates in the cells (carbonyl stress). Nonetheless, pursue of healthy aging has led the use of antioxidants as a means to disrupt age-associated physiological dysfunctions, dysregulated metabolic processes or prevention of many age-related diseases. Although it is still early to define their exact clinical benefits for treating age-related disease, a diet rich in polyphenolic or other forms of antioxidants does seem to offer hope in delaying the onset of age-related disorders. It is now clear that any deficiency in antioxidant vitamins, inadequate enzymatic antioxidant defenses can distinctive for many age-related disease, and protein carbonylation can used as an indicator of oxidative stress associated diseases and aging status. This review examines antioxidant compounds and plant polyphenols as redox regulators in health, disease and aging processes with hope that a better understanding of the many mechanisms involved with these distinct compounds, which may lead to better health and novel treatment approaches for age-related diseases.
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Affiliation(s)
- Volkan Ergin
- Cellular Stress Response and Signal Transduction Research Laboratory, Department of Medical Pharmacology, Faculty of Medicine, Gazi University, Ankara, Turkey
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Abstract
BACKGROUND Antioxidants and dietary fiber are postulated to have preventive effects on diabetic retinopathy, but evidence is lacking. We investigated this association in a cohort with type 2 diabetes 40-70 years of age with hemoglobin (Hb)A1C ≥6.5%, originally part of the Japan Diabetes Complications Study. METHODS After excluding people who did not respond to a dietary survey and patients with diabetic retinopathy or a major ocular disease at baseline, we analyzed 978 patients. Baseline dietary intake was assessed by a food frequency questionnaire based on food groups and 24-hour dietary records. Primary outcome was incident diabetic retinopathy determined using international severity scales. RESULTS Mean fruit intake in quartiles ranged from 23 to 253 g/day, with increasing trends across quartiles of fruit intake for vitamin C, vitamin E, carotene, retinol equivalent, dietary fiber, potassium, and sodium. Mean energy intake ranged from 1644 to 1863 kcal/day, and fat intake was approximately 25%. HbA1C, body mass index, triglycerides, and systolic blood pressure were well controlled. During the 8-year follow-up, the numbers of incident cases of diabetic retinopathy from the first through the fourth quartiles of fruit intake were 83, 74, 69, and 59. Multivariate-adjusted hazard ratios for the second, third, and fourth quartiles of fruit intake compared with the first quartile were 0.66 (95% confidence interval = 0.46-0.92), 0.59 (0.41-0.85), and 0.48 (0.32-0.71) (test for trend, P < 0.01). There was no substantial effect modification by age, sex, HbA1C, diabetes duration, overweight, smoking, and hypertension. Risk for diabetic retinopathy declined with increased intake of fruits and vegetables, vitamin C, and carotene. CONCLUSION Increased fruit intake in ranges commonly consumed was associated with reduced incident diabetic retinopathy among patients adhering to a low-fat energy-restricted diet.
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Elsherbiny NM, Ahmad S, Naime M, Elsherbini AM, Fulzele S, Al-Gayyar MM, Eissa LA, El-Shishtawy MM, Liou GI. ABT-702, an adenosine kinase inhibitor, attenuates inflammation in diabetic retinopathy. Life Sci 2013; 93:78-88. [PMID: 23770229 DOI: 10.1016/j.lfs.2013.05.024] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 04/29/2013] [Accepted: 05/28/2013] [Indexed: 12/20/2022]
Abstract
AIMS This study was undertaken to determine the effect of an adenosine kinase inhibitor (AKI) in diabetic retinopathy (DR). We have shown previously that adenosine signaling via A2A receptors (A2AAR) is involved in retinal protection from diabetes-induced inflammation. Here we demonstrate that AKI-enhanced adenosine signaling provides protection from DR in mice. MAIN METHODS We targeted AK, the key enzyme in adenosine metabolism, using a treatment regime with the selective AKI, ABT-702 (1.5mg/kg intraperitoneally twice a week) commencing at the beginning of streptozotocin-induced diabetes at the age of eight weeks. This treatment, previously demonstrated to increase free adenosine levels in vivo, was maintained until the age of 16 weeks. Retinal inflammation was evaluated using Western blot, Real-Time PCR and immuno-staining analyses. Role of A2AAR signaling in the anti-inflammation effect of ABT-702 was analyzed in Amadori-glycated-albumin (AGA)-treated microglial cells. KEY FINDINGS At 16 weeks, when diabetic mice exhibit significant signs of retinal inflammation including up-regulation of oxidative/nitrosative stress, A2AAR, ENT1, Iba1, TNF-α, ICAM1, retinal cell death, and down-regulation of AK, the ABT-702 treated group showed lower signs of inflammation compared to control animals receiving the vehicle. The involvement of adenosine signaling in the anti-inflammation effect of ABT-702 was supported by the TNF-α release blocking effect of A2AAR antagonist in AGA-treated microglial cells. SIGNIFICANCE These results suggest a role for AK in regulating adenosine receptor signaling in the retina. Inhibition of AK potentially amplifies the therapeutic effects of site- and event-specific accumulation of extracellular adenosine, which is of highly translational impact.
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Wagenfeld L, von Domarus F, Weiss S, Klemm M, Richard G, Zeitz O. The effect of reactive oxygen species on the myogenic tone of rat ophthalmic arteries with and without endothelium. Graefes Arch Clin Exp Ophthalmol 2013; 251:2339-44. [DOI: 10.1007/s00417-013-2387-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 05/03/2013] [Accepted: 05/16/2013] [Indexed: 01/13/2023] Open
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Zhong Q, Mishra M, Kowluru RA. Transcription factor Nrf2-mediated antioxidant defense system in the development of diabetic retinopathy. Invest Ophthalmol Vis Sci 2013; 54:3941-8. [PMID: 23633659 DOI: 10.1167/iovs.13-11598] [Citation(s) in RCA: 162] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
PURPOSE Increase in reactive oxygen species (ROS) is one of the major retinal metabolic abnormalities associated with the development of diabetic retinopathy. NF-E2-related factor 2 (Nrf2), a redox sensitive factor, provides cellular defenses against the cytotoxic ROS. In stress conditions, Nrf2 dissociates from its cytosolic inhibitor, Kelch like-ECH-associated protein 1 (Keap1), and moves to the nucleus to regulate the transcription of antioxidant genes including the catalytic subunit of glutamylcysteine ligase (GCLC), a rate-limiting reduced glutathione (GSH) biosynthesis enzyme. Our aim is to understand the role of Nrf2-Keap1-GCLC in the development of diabetic retinopathy. METHODS Effect of diabetes on Nrf2-Keap1-GCLC pathway, and subcellular localization of Nrf2 and its binding with Keap1 was investigated in the retina of streptozotocin-induced diabetic rats. The binding of Nrf2 at GCLC was quantified by chromatin immunoprecipitation technique. The results were confirmed in isolated retinal endothelial cells, and also in the retina from human donors with diabetic retinopathy. RESULTS Diabetes increased retinal Nrf2 and its binding with Keap1, but decreased DNA-binding activity of Nrf2 and also its binding at the promoter region of GCLC. Similar impairments in Nrf2-Keap1-GCLC were observed in the endothelial cells exposed to high glucose and in the retina from donors with diabetic retinopathy. In retinal endothelial cells, glucose-induced impairments in Nrf2-GCLC were prevented by Nrf2 inducer tBHQ and also by Keap1-siRNA. CONCLUSIONS Due to increased binding of Nrf2 with Keap1, its translocation to the nucleus is compromised contributing to the decreased GSH levels. Thus, regulation of Nrf2-Keap1 by pharmacological or molecular means could serve as a potential adjunct therapy to combat oxidative stress and inhibit the development of diabetic retinopathy.
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Affiliation(s)
- Qing Zhong
- Kresge Eye Institute, Wayne State University, Detroit, MI, USA
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Lima VC, Rosen RB, Prata TS, Dorairaj S, Spielberg L, Maia M, Sallum JM. Association of age and macular pigment optical density using dual-wavelength autofluorescence imaging. Clin Ophthalmol 2013; 7:685-90. [PMID: 23589675 PMCID: PMC3622437 DOI: 10.2147/opth.s42549] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Background Several lines of evidence suggest that macular pigment may play a protective role against age-related macular degeneration, but the influence of age on macular pigment density levels remains unclear. This study was designed to investigate the relationship between age and the normal distribution of macular pigment optical density (MPOD) values surrounding the fovea. Methods Consecutive healthy subjects with no evidence of ocular disease were enrolled in this study. After inclusion, MPOD values were measured at specific eccentricities (0.5, 1, and 2 degrees) from the foveal center using a dual-wavelength autofluorescence method employing a modified confocal scanning laser ophthalmoscope. Whenever both eyes were eligible, one was randomly selected for analysis. The correlation between age and MPOD values was investigated using regression analysis. Results Thirty subjects (30 eyes) were included (mean age 48.6 ± 16.4 [range 23–77] years). Significant differences were found between MPOD values measured at 0.5, 1, and 2 degrees from the center of the fovea (0.49 ± 0.12 density units, 0.37 ± 0.11 density units, and 0.13 ± 0.05 density units, respectively, P < 0.05). Significant correlations between age and MPOD values at 0.5 and 1 degree were found (P ≤ 0.02). Values measured at 2 degrees did not correlate significantly with age (P = 0.06). Conclusion In healthy subjects, MPOD values were highest near the foveal center. These values appeared to increase during adulthood (peak at 45–50 years), followed by a gradual reduction after 60 years of age.
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Affiliation(s)
- Verônica Castro Lima
- Retina Service, Department of Ophthalmology, The New York Eye and Ear Infirmary, New York, NY ; Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
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Hollborn M, Chen R, Wiedemann P, Reichenbach A, Bringmann A, Kohen L. Cytotoxic effects of curcumin in human retinal pigment epithelial cells. PLoS One 2013; 8:e59603. [PMID: 23555722 PMCID: PMC3608655 DOI: 10.1371/journal.pone.0059603] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 02/18/2013] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Curcumin from turmeric is an ingredient in curry powders. Due to its antiinflammatory, antioxidant and anticarcinogenic effects, curcumin is a promising drug for the treatment of cancer and retinal diseases. We investigated whether curcumin alters the viability and physiological properties of human retinal pigment epithelial (RPE) cells in vitro. METHODOLOGY/PRINCIPAL FINDINGS Cellular proliferation was investigated with a bromodeoxy-uridine immunoassay, and chemotaxis was investigated with a Boyden chamber assay. Cell viability was determined by trypan blue exclusion. Apoptosis and necrosis rates were determined with a DNA fragmentation ELISA. Gene expression was determined by real-time PCR, and secretion of VEGF and bFGF was examined with ELISA. The phosphorylation level of proteins was revealed by Western blotting. The proliferation of RPE cells was slightly increased by curcumin at 10 µM and strongly reduced by curcumin above 50 µM. Curcumin at 50 µM increased slightly the chemotaxis of the cells. Curcumin reduced the expression and secretion of VEGF under control conditions and abolished the VEGF secretion induced by PDGF and chemical hypoxia. Whereas low concentrations of curcumin stimulated the expression of bFGF and HGF, high concentrations caused downregulation of both factors. Curcumin decreased dose-dependently the viability of RPE cells via induction of early necrosis (above 10 µM) and delayed apoptosis (above 1 µM). The cytotoxic effect of curcumin involved activation of caspase-3 and calpain, intracellular calcium signaling, mitochondrial permeability, oxidative stress, increased phosphorylation of p38 MAPK and decreased phosphorylation of Akt protein. CONCLUSION It is concluded that curcumin at concentrations described to be effective in the treatment of tumor cells and in inhibiting death of retinal neurons (∼10 µM) has adverse effects on RPE cells. It is suggested that, during the intake of curcumin as concomitant therapy of cancer or in the treatment of eye diseases, retinal function should be monitored carefully.
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Affiliation(s)
- Margrit Hollborn
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany.
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