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Rodent Models of Diabetic Retinopathy as a Useful Research Tool to Study Neurovascular Cross-Talk. BIOLOGY 2023; 12:biology12020262. [PMID: 36829539 PMCID: PMC9952991 DOI: 10.3390/biology12020262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 02/01/2023] [Accepted: 02/03/2023] [Indexed: 02/11/2023]
Abstract
Diabetes is a group of metabolic diseases leading to dysfunction of various organs, including ocular complications such as diabetic retinopathy (DR). Nowadays, DR treatments involve invasive options and are applied at the sight-threatening stages of DR. It is important to investigate noninvasive or pharmacological methods enabling the disease to be controlled at the early stage or to prevent ocular complications. Animal models are useful in DR laboratory practice, and this review is dedicated to them. The first part describes the characteristics of the most commonly used genetic rodent models in DR research. The second part focuses on the main chemically induced models. The authors pay particular attention to the streptozotocin model. Moreover, this section is enriched with practical aspects and contains the current protocols used in research in the last three years. Both parts include suggestions on which aspect of DR can be tested using a given model and the disadvantages of each model. Although animal models show huge variability, they are still an important and irreplaceable research tool. Note that the choice of a research model should be thoroughly considered and dependent on the aspect of the disease to be analyzed.
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Alkharfy KM, Ahmad A, Siddiquei MM, Ghulam M, El-Asrar AA. Thymoquinone Attenuates Retinal Expression of Mediators and Markers of Neurodegeneration in a Diabetic Animal Model. Curr Mol Pharmacol 2023; 16:188-196. [PMID: 35049444 DOI: 10.2174/1874467215666220113105300] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/07/2021] [Accepted: 10/21/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND Diabetic retinopathy (DR) is a slow eye disease that affects the retina due to a long-standing uncontrolled diabetes mellitus. Hyperglycemia-induced oxidative stress can lead to neuronal damage leading to DR. OBJECTIVE The aim of the current investigation is to assess the protective effects of thymoquinone (TQ) as a potential compound for the treatment and/or prevention of neurovascular complications of diabetes, including DR. METHODS Diabetes was induced in rats by the administration of streptozotocin (55 mg/kg intraperitoneally, i.p.). Subsequently, diabetic rats were treated with either TQ (2 mg/kg i.p.) or vehicle on alternate days for three weeks. A healthy control group was also run in parallel. At the end of the treatment period, animals were euthanized, and the retinas were collected and analyzed for the expression levels of brain-derived neurotrophic factor (BDNF), tyrosine hydroxylase (TH), nerve growth factor receptor (NGFR), and caspase-3 using Western blotting techniques in the retina of diabetic rats and compared with the normal control rats. In addition, dichlorofluorescein (DCF) levels in the retina were assessed as a marker of reactive oxygen species (ROS), and blood-retinal barrier breakdown (BRB) was examined for vascular permeability. The systemic effects of TQ treatments on glycemic control, kidney and liver functions were also assessed in all groups. RESULTS Diabetic animals treated with TQ showed improvements in the liver and kidney functions compared with control diabetic rats. Normalization in the levels of neuroprotective factors, including BDNF, TH, and NGFR, was observed in the retina of diabetic rats treated with TQ. In addition, TQ ameliorated the levels of apoptosis regulatory protein caspase-3 in the retina of diabetic rats and reduced disruption of the blood-retinal barrier, possibly through a reduction in reactive oxygen species (ROS) generation. CONCLUSION These findings suggest that TQ harbors a significant potential to limit the neurodegeneration and retinal damage that can be provoked by hyperglycemia in vivo.
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Affiliation(s)
- Khalid M Alkharfy
- Department of Clinical Pharmacy, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Ajaz Ahmad
- Department of Clinical Pharmacy, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Mohammad Mairaj Siddiquei
- Department of Ophthalmology, College of Medicine, King Abdul Aziz Hospital, King Saud University, Riyadh 11451, Saudi Arabia
| | - Mohammad Ghulam
- Department of Ophthalmology, College of Medicine, King Abdul Aziz Hospital, King Saud University, Riyadh 11451, Saudi Arabia
| | - Ahmed Abu El-Asrar
- Department of Ophthalmology, College of Medicine, King Abdul Aziz Hospital, King Saud University, Riyadh 11451, Saudi Arabia
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Development of surface modified nanoparticles of curcumin for topical treatment of diabetic retinopathy: In vitro, ex vivo and in vivo investigation. J Drug Deliv Sci Technol 2022. [DOI: 10.1016/j.jddst.2022.103835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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4
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Mechanism of glycometabolism regulation by bioactive compounds from the fruits of Lycium barbarum: A review. Food Res Int 2022; 159:111408. [DOI: 10.1016/j.foodres.2022.111408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/30/2022] [Accepted: 05/22/2022] [Indexed: 11/21/2022]
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Escandon P, Vasini B, Whelchel AE, Nicholas SE, Matlock HG, Ma JX, Karamichos D. The role of peroxisome proliferator-activated receptors in healthy and diseased eyes. Exp Eye Res 2021; 208:108617. [PMID: 34010603 PMCID: PMC8594540 DOI: 10.1016/j.exer.2021.108617] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 05/03/2021] [Accepted: 05/05/2021] [Indexed: 12/23/2022]
Abstract
Peroxisome Proliferator-Activated Receptors (PPARs) are a family of nuclear receptors that play essential roles in modulating cell differentiation, inflammation, and metabolism. Three subtypes of PPARs are known: PPAR-alpha (PPARα), PPAR-gamma (PPARγ), and PPAR-beta/delta (PPARβ/δ). PPARα activation reduces lipid levels and regulates energy homeostasis, activation of PPARγ results in regulation of adipogenesis, and PPARβ/δ activation increases fatty acid metabolism and lipolysis. PPARs are linked to various diseases, including but not limited to diabetes, non-alcoholic fatty liver disease, glaucoma and atherosclerosis. In the past decade, numerous studies have assessed the functional properties of PPARs in the eye and key PPAR mechanisms have been discovered, particularly regarding the retina and cornea. PPARγ and PPARα are well established in their functions in ocular homeostasis regarding neuroprotection, neovascularization, and inflammation, whereas PPARβ/δ isoform function remains understudied. Naturally, studies on PPAR agonists and antagonists, associated with ocular pathology, have also gained traction with the development of PPAR synthetic ligands. Studies on PPARs has significantly influenced novel therapeutics for diabetic eye disease, ocular neuropathy, dry eye, and age-related macular degeneration (AMD). In this review, therapeutic potentials and implications will be highlighted, as well as reported adverse effects. Further investigations are necessary before any of the PPARs ligands can be utilized, in the clinics, to treat eye diseases. Future research on the prominent role of PPARs will help unravel the complex mechanisms involved in order to prevent and treat ocular diseases.
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Affiliation(s)
- Paulina Escandon
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Brenda Vasini
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Amy E Whelchel
- Department of Physiology, University of Oklahoma Health Sciences Center, 940 Stanton L Young, Oklahoma City, OK, USA
| | - Sarah E Nicholas
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - H Greg Matlock
- Department of Physiology, University of Oklahoma Health Sciences Center, 940 Stanton L Young, Oklahoma City, OK, USA
| | - Jian-Xing Ma
- Department of Physiology, University of Oklahoma Health Sciences Center, 940 Stanton L Young, Oklahoma City, OK, USA; Harold Hamm Oklahoma Diabetes Center, 1000 N Lincoln Blvd, Oklahoma City, OK, USA
| | - Dimitrios Karamichos
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA.
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Li XF, Jiang GB, Cheng SY, Song YF, Deng C, Niu YM, Cai JW. Association between PPAR-γ2 gene polymorphisms and diabetic retinopathy risk: a meta-analysis. Aging (Albany NY) 2021; 13:5136-5149. [PMID: 33535175 PMCID: PMC7950267 DOI: 10.18632/aging.202433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 12/09/2020] [Indexed: 11/29/2022]
Abstract
A close association between peroxisome proliferator-activated receptor-γ2 (PPAR-γ2) and the development of diabetic retinopathy (DR) has been previously suggested. Herein, a meta-analysis was conducted to explore the association between PPAR-γ2 polymorphisms and DR risk by performing a systematic search and quantitative analysis. Overall, fourteen articles involving 10,527 subjects were included. The pooled results did not reveal an association between PPAR-γ2 rs1801282 C/G and DR susceptibility in the overall population (e.g., the dominant model: CG+GG vs. CC, OR=0.85, 95% CI=0.69-1.06, P=0.15, I2=62.9%). Furthermore, heterogeneity tests, cumulative analyses, sensitivity analyses, and publication bias analyses were conducted and showed that the results were robust. Similarly, race-based subgroup analyses and other subgroup analyses did not reveal an association between the rs1801282 C/G and DR susceptibility. In addition, no significant association was observed between PPAR-γ2 rs3856806 C/T polymorphism and DR risk (e.g., the dominant model: CT+TT vs. CC, OR=1.12, 95%CI=0.91-1.37, P=0.28, I2=27.0%). Overall, based on the current sample size and the level of evidence presented in the study, the results suggest that PPAR-γ2 gene polymorphisms are not associated with DR risk.
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Affiliation(s)
- Xue-Feng Li
- Department of Endocrinology, Taihe Hospital, Hubei Key Laboratory of Embryonic Stem Cell Research, Hubei University of Medicine, Shiyan 442000, China
| | - Guang-Bin Jiang
- Department of Radiology, Suizhou Hospital, Hubei University of Medicine, Suizhou Central Hospital, Suizhou 441300, China
| | - Shi-Yan Cheng
- Department of Respiratory Medicine, Suizhou Hospital, Hubei University of Medicine, Suizhou Central Hospital, Suizhou 441300, China
| | - Ya-Feng Song
- The Personnel Section, Taihe Hospital, Hubei University of Medicine, Shiyan 442000, China
| | - Cai Deng
- Department of Stomatology, Evidence-Based Medicine and Clinical Research, Taihe Hospital, Hubei Key Laboratory of Embryonic Stem Cell Research, Hubei University of Medicine, Shiyan 442000, P.R. China
| | - Yu-Ming Niu
- Department of Endocrinology, Taihe Hospital, Hubei Key Laboratory of Embryonic Stem Cell Research, Hubei University of Medicine, Shiyan 442000, China.,Department of Stomatology, Evidence-Based Medicine and Clinical Research, Taihe Hospital, Hubei Key Laboratory of Embryonic Stem Cell Research, Hubei University of Medicine, Shiyan 442000, P.R. China
| | - Jun-Wei Cai
- Department of Endocrinology, Taihe Hospital, Hubei Key Laboratory of Embryonic Stem Cell Research, Hubei University of Medicine, Shiyan 442000, China
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Urner S, Ho F, Jha JC, Ziegler D, Jandeleit-Dahm K. NADPH Oxidase Inhibition: Preclinical and Clinical Studies in Diabetic Complications. Antioxid Redox Signal 2020; 33:415-434. [PMID: 32008354 DOI: 10.1089/ars.2020.8047] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Significance: Oxidative stress plays a critical role in the development and progression of serious micro- and macrovascular complications of diabetes. Nicotinamide adenine dinucleotide phosphate oxidase (NOX)-derived reactive oxygen species (ROS) significantly contribute to oxidative stress-associated inflammatory pathways that lead to tissue damage of different organs, including the kidneys, retina, brain, nerves, and the cardiovascular system. Recent Advances: Preclinical studies, including genetic-modified mouse models or cell culture models, have revealed the role of specific NOX isoforms in different diabetic complications, and suggested them as a promising target for the treatment of these diseases. Critical Issues: In this review, we provide an overview of the role of ROS and oxidative stress in macrovascular complications, such as stroke, myocardial infarction, coronary artery disease, and peripheral vascular disease that are all mainly driven by atherosclerosis, as well as microvascular complications, such as diabetic retinopathy, nephropathy, and neuropathy. We summarize conducted genetic deletion studies of different Nox isoforms as well as pharmacological intervention studies using NOX inhibitors in the context of preclinical as well as clinical research on diabetic complications. Future Directions: We outline the isoforms that are most promising for future clinical trials in the context of micro- and macrovascular complications of diabetes.
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Affiliation(s)
- Sofia Urner
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich-Heine University, Düsseldorf, Germany
| | - Florence Ho
- Department of Diabetes, Central Clinical School, Monash University, Melbourne, Australia
| | - Jay C Jha
- Department of Diabetes, Central Clinical School, Monash University, Melbourne, Australia
| | - Dan Ziegler
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich-Heine University, Düsseldorf, Germany
| | - Karin Jandeleit-Dahm
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich-Heine University, Düsseldorf, Germany
- Department of Diabetes, Central Clinical School, Monash University, Melbourne, Australia
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Association of Peroxisome Proliferator-Activated Receptors (PPARs) with Diabetic Retinopathy in Human and Animal Models: Analysis of the Literature and Genome Browsers. PPAR Res 2020; 2020:1783564. [PMID: 32190036 PMCID: PMC7072119 DOI: 10.1155/2020/1783564] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 11/03/2019] [Accepted: 02/07/2020] [Indexed: 01/13/2023] Open
Abstract
Diabetic retinopathy (DR) is a condition that develops after long-lasting and poorly handled diabetes and is presently the main reason for blindness among elderly and youth. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors that are involved in carbohydrate and fatty-acid metabolism and have also been associated with DR. Three PPAR isoforms are known: PPARG, PPARA, and PPARD. In the present study, we retrieved articles reporting associations between PPARs and DR from PubMed database and compiled the data in two catalogues, for human and animal models. Extracted data was then complemented with additional relevant genomic information. Seven retrieved articles reported testing an association between PPARs with DR in human. Four of them concluded association of PPARG and PPARA with DR in European and Asian populations, having a protective role on DR development. One study reported pathogenic role of PPARG, while two articles reported no association between PPARG and DR among Indian and Chinese populations. Six retrieved articles reported testing of involvement of PPARG and PPARA in DR in animal models, including mouse and rat. The review includes case-control studies, meta-analysis, expression studies, animal models, and cell line studies. Despite a large number of documented sequence variants of the PPAR genes available in genome browsers, researchers usually focus on a small set of previously reported variants. Data extraction from Ensembl genome browser revealed several sequence variants with predicted deleterious effect on protein function which present candidates for further experimental validation. Results of the present analysis will enable more holistic approach for understanding of PPARs in DR development. Additionally, developed catalogues present a baseline for standardized reporting of PPAR-phenotype association in upcoming studies.
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New anti-hyperglycaemic agents for type 2 diabetes and their effects on diabetic retinopathy. Eye (Lond) 2019; 33:1842-1851. [PMID: 31227789 DOI: 10.1038/s41433-019-0494-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 04/19/2019] [Accepted: 05/21/2019] [Indexed: 12/11/2022] Open
Abstract
There has been an increase in the range of non-insulin anti-hyperglycaemic agents used to treat type 2 diabetes. With the globally rising rates of type 2 diabetes and complications such as diabetic retinopathy, it is important for ophthalmologists to be aware of these new agents and their impacts on diabetic retinopathy and diabetic macular oedema. We conducted a review of the literature to determine if there were any beneficial or harmful effects of the currently used anti-hyperglycaemic agents on diabetic retinopathy or diabetic macular oedema. Our review of the current literature found that apart from thiazolidinediones, anti-hyperglycaemic agents have been reported to have beneficial or neutral effects on diabetic eye complications. Thiazolidinediones (pioglitazone is the only one currently available) have been linked to incident or worsening diabetic macular oedema, although the rate is believed to be low. Glucagon-like peptide 1 (GLP1) agonists (incretins) in general are beneficial except semaglutide which is associated with increased rates of diabetic retinopathy complications. These results have implications for selection of anti-hyperglycaemic agents for patients with diabetic retinopathy or macular oedema. Further studies need to be conducted to identify if reported beneficial effects are independent of the impact of glycaemic control. Early worsening of retinopathy with tight glycaemic control should also be noted in interpretation of future studies.
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Castelli V, d'Angelo M, Antonosante A, Catanesi M, Benedetti E, Desideri G, Cimini A. Physiology and Pathophysiology of PPARs in the Eye. NUCLEAR RECEPTOR RESEARCH 2018. [DOI: 10.11131/2018/101370] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Affiliation(s)
- Vanessa Castelli
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy
| | - Michele d'Angelo
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy
| | - Andrea Antonosante
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy
| | - Mariano Catanesi
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy
| | - Elisabetta Benedetti
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy
| | | | - Annamaria Cimini
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy
- Sbarro Institute for Cancer Research and Molecular Medicine, Department of Biology, Temple University, Philadelphia, USA
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Vallée A, Lecarpentier Y, Guillevin R, Vallée JN. PPARγ agonists: Potential treatments for exudative age-related macular degeneration. Life Sci 2017; 188:123-130. [PMID: 28887057 DOI: 10.1016/j.lfs.2017.09.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 08/29/2017] [Accepted: 09/05/2017] [Indexed: 12/22/2022]
Abstract
Choroidal neovascularization (CNV) characterizes the progression of exudative age-related macular degeneration (AMD) with the deterioration in the central vision. Vascular inflammation, and overproduction of inflammatory cytokines, growth factors and aberrant endothelial cell migration, initiate defective blood vessel proliferation in exudative AMD. CNV formation is initiated by the interplay between inflammation, the hallmark of exudative AMD, and the activation of WNT/β-catenin pathway. Upregulation of WNT/β-catenin pathway involves activation of PI3K/Akt pathway and then the Warburg effect to produce lactate. Lactate production generates VEGF expression and then participates to the initiation of CNV in exudative AMD. WNT/β-catenin pathway and PPARγ act in an opposite manner in several diseases. We focus this review on the interplay between PPARγ and canonical WNT/β-catenin pathway and the anti-inflammatory role of PPARγ in exudative AMD. In exudative AMD, PPARγ agonists downregulate inflammation and the WNT/β-catenin pathway. PPARγ agonists can appear as promising treatment against the initiation and the progression of CNV in exudative AMD.
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Affiliation(s)
- Alexandre Vallée
- Experimental and Clinical Neurosciences Laboratory, INSERM U1084, University of Poitiers, Poitiers, France; Laboratoire de Mathématiques et Applications (LMA), UMR CNRS 7348, Université de Poitiers, France.
| | - Yves Lecarpentier
- Centre de Recherche Clinique, Grand Hôpital de l'Est Francilien (GHEF), Meaux, France
| | - Rémy Guillevin
- Université de Poitiers et CHU de Poitiers, DACTIM, Laboratoire de Mathématiques et Applications, UMR CNRS 7348, SP2MI, Futuroscope, France
| | - Jean-Noël Vallée
- Laboratoire de Mathématiques et Applications (LMA), UMR CNRS 7348, Université de Poitiers, France; CHU Amiens Picardie, Université Picardie Jules Verne (UPJV), Amiens, France
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Usui-Ouchi A, Ouchi Y, Ebihara N. The peroxisome proliferator-activated receptor pan-agonist bezafibrate suppresses microvascular inflammatory responses of retinal endothelial cells and vascular endothelial growth factor production in retinal pigmented epithelial cells. Int Immunopharmacol 2017; 52:70-76. [PMID: 28866026 DOI: 10.1016/j.intimp.2017.08.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 08/08/2017] [Accepted: 08/27/2017] [Indexed: 01/01/2023]
Abstract
A randomized clinical trial showed the beneficial effects of the selective peroxisome proliferator-activated receptor (PPAR)-α agonist, fenofibrate, in reducing the progression of diabetic retinopathy independent of serum lipid levels. All subtypes of PPAR (PPAR-α, PPAR-γ, and PPAR-β/δ) have been reported to play a key role in microvascular inflammation and angiogenesis. Therefore, the agonistic function of fenofibrate against the PPAR-α has been suggested to contribute to its medicinal effect. Furthermore, bezafibrate is a fibrate drug commonly used as a lipid-lowering agent to treat hyperlipidemia and acts as a pan-agonist of all PPARs subtypes. However, the effects of bezafibrate in diabetic retinopathy remain unclear. Therefore, the purpose of this study was to investigate the effects of bezafibrate on retinal microvascular inflammation. Bezafibrate was not cytotoxic against human retinal microvascular endothelial cells (HRMECs) and human retinal pigment epithelial cells (ARPE-19 cells) treated with <100 and 200μM bezafibrate, respectively. In HRMECs, the expression levels of tumor necrosis factor (TNF)-α-induced monocyte chemoattractant protein (MCP)-1, intercellular adhesion molecule (ICAM)-1, and vascular cell adhesion molecule (VCAM)-1 were significantly suppressed by bezafibrate in a dose-dependent manner. TNF-α-induced nuclear translocation of nuclear factor (NF)-κB p65 and cell migration were also significantly inhibited in bezafibrate-treated HRMECs. Furthermore, bezafibrate treatment significantly suppressed interleukin (IL)-1β-induced vascular endothelial growth factor (VEGF) production in ARPE-19 cells. These results suggest that bezafibrate has beneficial effects on retinal microvascular inflammation. Our study demonstrates the therapeutic potential of bezafibrate for managing diabetic retinopathy.
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Affiliation(s)
- Ayumi Usui-Ouchi
- Department of Ophthalmology, Juntendo University Urayasu Hospital, Urayasu, Chiba, Japan.
| | - Yasuo Ouchi
- Department of Mucosal Immunology, School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
| | - Nobuyuki Ebihara
- Department of Ophthalmology, Juntendo University Urayasu Hospital, Urayasu, Chiba, Japan.
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Size-selective opening of the blood-brain barrier by targeting endothelial sphingosine 1-phosphate receptor 1. Proc Natl Acad Sci U S A 2017; 114:4531-4536. [PMID: 28396408 DOI: 10.1073/pnas.1618659114] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The vasculature of the central nervous system (CNS) forms a selective barrier termed the blood-brain barrier (BBB). Disruption of the BBB may contribute to various CNS diseases. Conversely, the intact BBB restricts efficient penetration of CNS-targeted drugs. Here, we report the BBB-regulatory role of endothelial sphingosine 1-phosphate (S1P) receptor-1, a G protein-coupled receptor known to promote the barrier function in peripheral vessels. Endothelial-specific S1pr1 knockout mice (S1pr1iECKO ) showed BBB breach for small-molecular-mass fluorescence tracers (<3 kDa), but not larger tracers (>10 kDa). Chronic BBB leakiness was associated with cognitive impairment, as assessed by the novel object recognition test, but not signs of brain inflammation. Brain microvessels of S1pr1iECKO mice showed altered subcellular distribution of tight junctional proteins. Pharmacological inhibition of S1P1 function led to transient BBB breach. These data suggest that brain endothelial S1P1 maintain the BBB by regulating the proper localization of tight junction proteins and raise the possibility that endothelial S1P1 inhibition may be a strategy for transient BBB opening and delivery of small molecules into the CNS.
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Stewart E, Saker S, Amoaku W. Dexamethasone reverses the effects of high glucose on human retinal endothelial cell permeability and proliferation in vitro. Exp Eye Res 2016; 151:75-81. [DOI: 10.1016/j.exer.2016.08.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 07/13/2016] [Accepted: 08/09/2016] [Indexed: 01/30/2023]
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15
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Gu X, Reagan AM, McClellan ME, Elliott MH. Caveolins and caveolae in ocular physiology and pathophysiology. Prog Retin Eye Res 2016; 56:84-106. [PMID: 27664379 DOI: 10.1016/j.preteyeres.2016.09.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 09/15/2016] [Accepted: 09/20/2016] [Indexed: 12/14/2022]
Abstract
Caveolae are specialized, invaginated plasma membrane domains that are defined morphologically and by the expression of signature proteins called, caveolins. Caveolae and caveolins are abundant in a variety of cell types including vascular endothelium, glia, and fibroblasts where they play critical roles in transcellular transport, endocytosis, mechanotransduction, cell proliferation, membrane lipid homeostasis, and signal transduction. Given these critical cellular functions, it is surprising that ablation of the caveolae organelle does not result in lethality suggesting instead that caveolae and caveolins play modulatory roles in cellular homeostasis. Caveolar components are also expressed in ocular cell types including retinal vascular cells, Müller glia, retinal pigment epithelium (RPE), conventional aqueous humor outflow cells, the corneal epithelium and endothelium, and the lens epithelium. In the eye, studies of caveolae and other membrane microdomains (i.e., "lipid rafts") have lagged behind what is a substantial body of literature outside vision science. However, interest in caveolae and their molecular components has increased with accumulating evidence of important roles in vision-related functions such as blood-retinal barrier homeostasis, ocular inflammatory signaling, pathogen entry at the ocular surface, and aqueous humor drainage. The recent association of CAV1/2 gene loci with primary open angle glaucoma and intraocular pressure has further enhanced the need to better understand caveolar functions in the context of ocular physiology and disease. Herein, we provide the first comprehensive review of literature on caveolae, caveolins, and other membrane domains in the context of visual system function. This review highlights the importance of caveolae domains and their components in ocular physiology and pathophysiology and emphasizes the need to better understand these important modulators of cellular function.
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Affiliation(s)
- Xiaowu Gu
- Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Alaina M Reagan
- Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Mark E McClellan
- Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Michael H Elliott
- Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
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Role of Peroxisome Proliferator-Activated Receptor γ in Ocular Diseases. J Ophthalmol 2015; 2015:275435. [PMID: 26146566 PMCID: PMC4471377 DOI: 10.1155/2015/275435] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 05/19/2015] [Indexed: 01/14/2023] Open
Abstract
Peroxisome proliferator-activated receptor γ (PPAR γ), a member of the nuclear receptor superfamily, is a ligand-activated transcription factor that plays an important role in the control of a variety of physiological processes. The last decade has witnessed an increasing interest for the role played by the agonists of PPAR γ in antiangiogenesis, antifibrosis, anti-inflammation effects and in controlling oxidative stress response in various organs. As the pathologic mechanisms of major blinding diseases, such as age-related macular degeneration (AMD), diabetic retinopathy (DR), keratitis, and optic neuropathy, often involve neoangiogenesis and inflammation- and oxidative stress-mediated cell death, evidences are accumulating on the potential benefits of PPAR γ to improve or prevent these vision threatening eye diseases. In this paper we describe what is known about the role of PPAR γ in the ocular pathophysiological processes and PPAR γ agonists as novel adjuvants in the treatment of eye diseases.
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Thakran S, Zhang Q, Morales-Tirado V, Steinle JJ. Pioglitazone restores IGFBP-3 levels through DNA PK in retinal endothelial cells cultured in hyperglycemic conditions. Invest Ophthalmol Vis Sci 2014; 56:177-84. [PMID: 25525174 DOI: 10.1167/iovs.14-15550] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
PURPOSE Previously, we reported that pioglitazone prevented insulin resistance and cell death in type 2 diabetic retina by reducing TNFα and suppressor of cytokine signaling 3 (SOCS3) levels. Numerous reports suggest prominent vasoprotective effects of insulin growth factor binding protein-3 (IGFBP-3) in diabetic retinopathy. We hypothesized that pioglitazone protects against retinal cell apoptosis by regulating IGFBP-3 levels, in addition to reducing TNFα. The current study explored potential IGFBP-3 regulatory pathways by pioglitazone in retinal endothelial cells cultured in high glucose. METHODS Primary human retinal endothelial cells (REC) were grown in normal (5 mM) and high glucose (25 mM) and treated with pioglitazone for 24 hours. Cell lysates were processed for Western blotting and ELISA analysis to evaluate IGFBP-3, TNFα, and cleaved caspase 3 protein levels. RESULTS Our results show that treatment with pioglitazone restored the high glucose-induced decrease in IGFBP-3 levels. This regulation was independent of TNFα actions, as reducing TNFα levels with siRNA did not prevent pioglitazone from increasing IGFBP-3 levels. Pioglitazone required protein kinase A (PKA) and DNA-dependent protein kinase (DNA PK) activity to regulate IGFBP-3, as specific inhibitors for each protein prevented pioglitazone-mediated normalization of IGFBP-3 in high glucose. Insulin growth factor binding protein-3 activity was increased and apoptosis decreased by pioglitazone, which was eliminated when serine site 156 of IGFBP-3 was mutated suggesting a key role of this phosphorylation site in pioglitazone actions. CONCLUSIONS Our findings suggest that pioglitazone mediates regulation of IGFBP-3 via activation of PKA/DNA PK pathway in hyperglycemic retinal endothelial cells.
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Affiliation(s)
- Shalini Thakran
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United States
| | - Qiuhua Zhang
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United States
| | - Vanessa Morales-Tirado
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United States Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Science Center, Memphis, Tennessee, United States
| | - Jena J Steinle
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United States Department of Anatomy & Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, United States Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, Tennessee, United States
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Shen W, Gao Y, Lu B, Zhang Q, Hu Y, Chen Y. Negatively regulating TLR4/NF-κB signaling via PPARα in endotoxin-induced uveitis. Biochim Biophys Acta Mol Basis Dis 2014; 1842:1109-20. [PMID: 24717912 DOI: 10.1016/j.bbadis.2014.03.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 03/27/2014] [Accepted: 03/31/2014] [Indexed: 02/06/2023]
Abstract
Toll-like receptor (TLR) signaling plays a fundamental role in the induction and progression of autoimmune disease. In the present study, we showed that lipopolysaccharide (LPS), a TLR4 ligand, functions as an antagonist of peroxisome proliferator-activated receptor alpha (PPARα), a nuclear transcription factor. Using endotoxin induced uveitis (EIU) as a model, we found that TLR was negatively regulated by PPARα. Our data revealed that treatment with the PPARα agonist fenofibrate dramatically prevented LPS-induced uveitis and inhibited TLR/ Nuclear factor-kappaB (NF-κB) signaling during inflammation. Evaluation of the severity of anterior uveitis further showed that PPARα agonist treatment significantly decreased inflammatory cell infiltration, total protein concentration, vessel density, inflammatory cytokine production, and clinical scores in the anterior section of the eye during EIU. Moreover, fenofibrate administration recovered retinal function and decreased the production of inflammatory cytokines, retinal vascular leukostasis, and inflammatory cell infiltration into the posterior section of the eyes during EIU. In vitro studies further showed that down-regulation or deletion of PPARα led to increased TLR4 levels and the activation of NF-κB signaling in RPE cells and also blocked the anti-inflammatory effects of fenofibrate. Furthermore, activation or up-regulation of PPARα decreased TLR4 levels and inhibited the NF-κB signaling pathway induced by LPS in RPE cells. In TLR4-expressing reporter cells, activation or up-regulation of PPARα partially inhibited the activation of NF-κB and also decreased TLR4 transcriptional activity. In conclusion, the activation of PPARα represents a novel therapeutic strategy for human uveitis, as PPARα negatively regulates TLR4 activity and therefore exerts anti-inflammatory actions.
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Affiliation(s)
- Wei Shen
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Yang Gao
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, PR China
| | - Boyu Lu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, PR China
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, PR China
| | - Yang Hu
- Arthritis and Clinical Immunology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA.
| | - Ying Chen
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
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Ezquer F, Ezquer M, Arango-Rodriguez M, Conget P. Could donor multipotent mesenchymal stromal cells prevent or delay the onset of diabetic retinopathy? Acta Ophthalmol 2014; 92:e86-95. [PMID: 23773776 DOI: 10.1111/aos.12113] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Diabetes mellitus is a complex metabolic disease that has become a global epidemic with more than 285 million cases worldwide. Major medical advances over the past decades have substantially improved its management, extending patients' survival. The latter is accompanied by an increased risk of developing chronic macro- and microvascular complications. Amongst them, diabetic retinopathy (DR) is the most common and frightening. Furthermore, during the past two decades, it has become the leading cause of visual loss. Irrespective of the type of diabetes, DR follows a well-known clinical and temporal course characterized by pericytes and neuronal cell loss, formation of acellular-occluded capillaries, occasional microaneurysms, increased leucostasis and thickening of the vascular basement membrane. These alterations progressively affect the integrity of retinal microvessels, leading to the breakdown of the blood-retinal barrier, widespread haemorrhage and neovascularization. Finally, tractional retinal detachment occurs leading to blindness. Nowadays, there is growing evidence that local inflammation and oxidative stress play pivotal roles in the pathogenesis of DR. Both processes have been associated with pericytes and neuronal degeneration observed early during DR progression. They may also be linked to sustained retinal vasculature damage that results in abnormal neovascularization. Currently, DR therapeutic options depend on highly invasive surgical procedures performed only at advanced stages of the disease, and which have proved to be ineffective to restore visual acuity. Therefore, the availability of less invasive and more effective strategies aimed to prevent or delay the onset of DR is highly desirable. Multipotent mesenchymal stromal cells, also referred to as mesenchymal stem cells (MSCs), are promising healing agents as they contribute to tissue regeneration by pleiotropic mechanisms, with no evidence of significant adverse events. Here, we revise the pathophysiology of DR to identify therapeutic targets for donor MSCs. Also, we discuss whether an MSC-based therapy could prevent or delay the onset of DR.
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Affiliation(s)
- Fernando Ezquer
- Institute of Science, Faculty of Medicine Clinica Alemana Universidad del Desarrollo, Lo Barnechea, Santiago, Chile
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20
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Abu El-Asrar AM. Evolving strategies in the management of diabetic retinopathy. Middle East Afr J Ophthalmol 2014; 20:273-82. [PMID: 24339676 PMCID: PMC3841944 DOI: 10.4103/0974-9233.119993] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Diabetic retinopathy (DR), the most common long-term complication of diabetes mellitus, remains one of the leading causes of blindness worldwide. Tight glycemic and blood pressure control has been shown to significantly decrease the risk of development as well as the progression of retinopathy and represents the cornerstone of medical management of DR. The two most threatening complications of DR are diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR). Focal/grid photocoagulation and panretinal photocoagulation are standard treatments for both DME and PDR, respectively. Focal/grid photocoagulation is a better treatment than intravitreal triamcinolone acetonide in eyes with DME. Currently, most experts consider combination focal/grid laser therapy and pharmacotherapy with intravitreal antivascular endothelial growth factor agents in patients with center-involving DME. Combination therapy reduces the frequency of injections needed to control edema. Vitrectomy with removal of the posterior hyaloid seems to be effective in eyes with persistent diffuse DME, particularly in eyes with associated vitreomacular traction. Emerging therapies include fenofibrate, ruboxistaurin, renin-angiotensin system blockers, peroxisome proliferator-activated receptor gamma agonists, pharmacologic vitreolysis, and islet cell transplantation.
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Affiliation(s)
- Ahmed M Abu El-Asrar
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
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21
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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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22
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Al-Shabrawey M, Elsherbiny M, Nussbaum J, Othman A, Megyerdi S, Tawfik A. Targeting Neovascularization in Ischemic Retinopathy: Recent Advances. EXPERT REVIEW OF OPHTHALMOLOGY 2014; 8:267-286. [PMID: 25598837 DOI: 10.1586/eop.13.17] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Pathological retinal neovascularization (RNV) is a common micro-vascular complication in several retinal diseases including retinopathy of prematurity, diabetic retinopathy, age-related macular degeneration and central vein occlusion. The current therapeutic modalities of RNV are invasive and although they may slow or halt the progression of the disease they are unlikely to restore normal acuity. Therefore, there is an urgent need to develop treatment modalities, which are less invasive and therefore associated with fewer procedural complications and systemic side effects. This review article summarizes our understanding of the pathophysiology and current treatment of RNV in ischemic retinopathies; lists potential therapeutic targets; and provides a framework for the development of future treatment modalities.
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Affiliation(s)
- Mohamed Al-Shabrawey
- Oral Biology/Anatomy, College of Dental Medicine, GeorgiaRegentsUniversity (GRU), Augusta GA, USA ; Ophthalmology and Vision Discovery Institute, Medical College of Georgia, GRU ; Anatomy, Mansoura Faculty of Medicine, Mansoura University-Egypt ; Vascular Biology Center, Medical College of Georgia, GRU
| | - Mohamed Elsherbiny
- Oral Biology/Anatomy, College of Dental Medicine, GeorgiaRegentsUniversity (GRU), Augusta GA, USA ; Ophthalmology and Vision Discovery Institute, Medical College of Georgia, GRU ; Anatomy, Mansoura Faculty of Medicine, Mansoura University-Egypt
| | - Julian Nussbaum
- Ophthalmology and Vision Discovery Institute, Medical College of Georgia, GRU
| | - Amira Othman
- Anatomy, Mansoura Faculty of Medicine, Mansoura University-Egypt
| | - Sylvia Megyerdi
- Oral Biology/Anatomy, College of Dental Medicine, GeorgiaRegentsUniversity (GRU), Augusta GA, USA
| | - Amany Tawfik
- Ophthalmology and Vision Discovery Institute, Medical College of Georgia, GRU ; Cellular Biology and Anatomy, Medical College of Georgia, GRU
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Peroxisome proliferator-activated receptor-γ agonist pioglitazone suppresses experimental autoimmune uveitis. Exp Eye Res 2013; 116:291-7. [DOI: 10.1016/j.exer.2013.09.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 09/11/2013] [Accepted: 09/27/2013] [Indexed: 12/31/2022]
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24
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Reactive oxygen species, Nox and angiotensin II in angiogenesis: implications for retinopathy. Clin Sci (Lond) 2013; 124:597-615. [PMID: 23379642 DOI: 10.1042/cs20120212] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Pathological angiogenesis is a key feature of many diseases including retinopathies such as ROP (retinopathy of prematurity) and DR (diabetic retinopathy). There is considerable evidence that increased production of ROS (reactive oxygen species) in the retina participates in retinal angiogenesis, although the mechanisms by which this occurs are not fully understood. ROS is produced by a number of pathways, including the mitochondrial electron transport chain, cytochrome P450, xanthine oxidase and uncoupled nitric oxide synthase. The family of NADPH oxidase (Nox) enzymes are likely to be important given that their primary function is to produce ROS. Seven isoforms of Nox have been identified named Nox1-5, Duox (dual oxidase) 1 and Duox2. Nox1, Nox2 and Nox4 have been most extensively studied and are implicated in the development of conditions such as hypertension, cardiovascular disease and diabetic nephropathy. In recent years, evidence has accumulated to suggest that Nox1, Nox2 and Nox4 participate in pathological angiogenesis; however, there is no clear consensus about which Nox isoform is primarily responsible. In terms of retinopathy, there is growing evidence that Nox contribute to vascular injury. The RAAS (renin-angiotensin-aldosterone system), and particularly AngII (angiotensin II), is a key stimulator of Nox. It is known that a local RAAS exists in the retina and that blockade of AngII and aldosterone attenuate pathological angiogenesis in the retina. Whether the RAAS influences the production of ROS derived from Nox in retinopathy is yet to be fully determined. These topics will be reviewed with a particular emphasis on ROP and DR.
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25
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Molecular Implications of the PPARs in the Diabetic Eye. PPAR Res 2013; 2013:686525. [PMID: 23431285 PMCID: PMC3575611 DOI: 10.1155/2013/686525] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 01/07/2013] [Accepted: 01/07/2013] [Indexed: 01/08/2023] Open
Abstract
Diabetic retinopathy (DR) remains as the leading cause of blindness among working age individuals in developed countries. Current treatments for DR (laser photocoagulation, intravitreal corticosteroids, intravitreal anti-VEGF agents, and vitreoretinal surgery) are applicable only at advanced stages of the disease and are associated with significant adverse effects. Therefore, new pharmacological treatments for the early stages of the disease are needed. Emerging evidence indicates that peroxisome proliferator-activator receptors (PPARs) agonists (in particular PPARα) are useful for the treatment of DR. However, the underlying molecular mechanisms are far from being elucidated. This paper mainly focuses on PPARs expression in the diabetic eye, its molecular implications, and the effect of PPAR agonists as a new approach for the treatment of DR. The availability of this new strategy will not only be beneficial in treating DR but may also result in a shift towards treating earlier stages of diabetic retinopathy, thus easing the burden of this devastating disease (Cheung et al. (2010)).
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26
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Mohammad G, Siddiquei MM, Othman A, Al-Shabrawey M, Abu El-Asrar AM. High-mobility group box-1 protein activates inflammatory signaling pathway components and disrupts retinal vascular-barrier in the diabetic retina. Exp Eye Res 2012; 107:101-9. [PMID: 23261684 DOI: 10.1016/j.exer.2012.12.009] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 12/10/2012] [Accepted: 12/13/2012] [Indexed: 01/15/2023]
Abstract
Extracellular high-mobility group box-1 (HMGB-1) functions as a pro-inflammatory cytokine and exhibits angiogenic effects. The purpose of this study was to investigate the expression of HMGB-1 signaling pathway components in the retinas of diabetic rats and to examine the effect of intravitreal administration of HMGB-1 on the retinas of rats. The retinas of diabetic and intravitreally injected HMGB-1 rats were studied using immunohistochemistry, Western blotting, co-immunoprecipitation and enzyme-linked immunosorbent assay. The effect of HMGB-1 on retinal endothelial cell barrier function was evaluated using electrical cell-substrate impedance sensing system (ECIS). Diabetes induced significant upregulation of the expression of HMGB-1, receptor for advanced glycation end products (RAGE), ERK(1/2) and nuclear transcription factor Kappa B (NF-κB), whereas the expression of toll-like receptor 2 (TLR2) and occludin was significantly downregulated. Co-immunoprecipitation studies revealed significant increase in interaction between HMGB-1 and RAGE. HMGB-1 reduced transendothelial electrical resistance of bovine retinal endothelial cells. Intravitreal administration of HMGB-1 to normal rats induced significant upregulation of intercellular adhesion molecule-1 (ICAM-1), soluble intercellular adhesion molecule-1 (sICAM-1), HMGB-1, RAGE, ERK(1/2), and NF-κB, and significantly increased retinal vascular permeability, whereas the expression of TLR2 and occludin was downregulated. Oral administration of glycyrrhizin, a specific inhibitor of HMGB-1, attenuated diabetes-induced upregulation of HMGB-1 expression, NF-κB activation and downregulation of occludin expression. Our findings provide evidence that in the diabetic retina, HMGB-1 possibly interacts with RAGE and activates ERK(1/2) and NF-κB to generate an inflammatory response and disrupt retinal vascular barrier.
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Affiliation(s)
- Ghulam Mohammad
- Department of Ophthalmology, College of Medicine, King Abdul Aziz University Hospital, King Saud University, P.O. Box 245, 11411 Riyadh, Saudi Arabia.
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27
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Song MK, Roufogalis BD, Huang THW. Modulation of diabetic retinopathy pathophysiology by natural medicines through PPAR-γ-related pharmacology. Br J Pharmacol 2012; 165:4-19. [PMID: 21480863 DOI: 10.1111/j.1476-5381.2011.01411.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes and remains a major cause of preventable blindness among adults at working age. DR involves an abnormal pathology of major retinal cells, including retinal pigment epithelium, microaneurysms, inter-retinal oedema, haemorrhage, exudates (hard exudates) and intraocular neovascularization. The biochemical mechanisms associated with hyperglycaemic-induced DR are through multifactorial processes. Peroxisome proliferator-activated receptor-γ (PPAR-γ) plays an important role in the pathogenesis of DR by inhibiting diabetes-induced retinal leukostasis and leakage. Despite DR causing eventual blindness, only a few visual or ophthalmic symptoms are observed until visual loss develops. Therefore, early medical interventions and prevention are the current management strategies. Laser photocoagulation therapy is the most common treatment. However, this therapy may cause retinal damage and scarring. Herbal and traditional natural medicines may provide an alternative to prevent or delay the progression of DR. This review provides an analysis of the therapeutic potential of herbal and traditional natural medicines or their active components for the slowdown of progression of DR and their possible mechanism through the PPAR-γ pathway.
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Affiliation(s)
- Min K Song
- Herbal Medicines Research and Education Centre, Faculty of Pharmacy, The University of Sydney, NSW, Australia
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28
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Song M, Salam N, Roufogalis BD, Huang T. Lycium barbarum (Goji Berry) extracts and its taurine component inhibit PPAR-γ-dependent gene transcription in human retinal pigment epithelial cells: Possible implications for diabetic retinopathy treatment. Biochem Pharmacol 2011; 82:1209-18. [DOI: 10.1016/j.bcp.2011.07.089] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 07/18/2011] [Accepted: 07/20/2011] [Indexed: 01/12/2023]
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Zhang W, Liu H, Rojas M, Caldwell RW, Caldwell RB. Anti-inflammatory therapy for diabetic retinopathy. Immunotherapy 2011; 3:609-28. [PMID: 21554091 DOI: 10.2217/imt.11.24] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Diabetic retinopathy (DR) is one of the most common complications of diabetes. This devastating disease is a leading cause of blindness in people of working age in industrialized countries and affects the daily lives of millions of people. Despite tight glycemic control, blood pressure control and lipid-lowering therapy, the number of DR patients keeps growing and therapeutic approaches are limited. Moreover, there are significant limitations and side effects associated with the current therapies. Thus, there is a great need for development of new strategies for prevention and treatment of DR. Studies have shown that DR has prominent features of chronic, subclinical inflammation. This article focuses on the role of inflammation in DR and summarizes the progress of studies of anti-inflammatory strategies for DR.
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Affiliation(s)
- Wenbo Zhang
- Vascular Biology Center, Georgia Health Sciences University, Augusta, GA 30912-2500, USA.
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Role of Peoxisome Proliferator Activator Receptor gamma on Blood Retinal Barrier Breakdown. PPAR Res 2011; 2008:679237. [PMID: 18309374 PMCID: PMC2248243 DOI: 10.1155/2008/679237] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Accepted: 07/10/2007] [Indexed: 11/17/2022] Open
Abstract
The retinal vessels have two barriers: the retinal pigment epithelium and the retinal vascular endothelium. Each barrier exhibits increased permeability under various pathological conditions. This condition is referred to as blood retinal barrier (BRB) breakdown. Clinically, the most frequently encountered condition causing BRB breakdown is diabetic retinopathy. In recent studies, inflammation has been linked to BRB breakdown and vascular leakage in diabetic retinopathy. Biological support for the role of inflammation in early diabetes is the adhesion of leukocytes to the retinal vasculature (leukostasis) observed in diabetic retinopathy. PPARγ is a member of a ligand-activated nuclear receptor superfamily and plays a critical role in a variety of biological processes, including adipogenesis, glucose metabolism, angiogenesis, and inflammation. There is now strong experimental evidence to support the theory that PPARγ inhibits diabetes-induced retinal leukostasis and leakage, playing an important role in the pathogenesis of diabetic retinopathy. Therapeutic targeting of PPARγ may be beneficial to diabetic retinopathy.
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PPARgamma Agonists: Potential as Therapeutics for Neovascular Retinopathies. PPAR Res 2011; 2008:164273. [PMID: 18509499 PMCID: PMC2396446 DOI: 10.1155/2008/164273] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2007] [Revised: 03/12/2008] [Accepted: 04/10/2008] [Indexed: 01/16/2023] Open
Abstract
The angiogenic, neovascular proliferative retinopathies, proliferative diabetic retinopathy (PDR), and age-dependent macular degeneration (AMD) complicated by choroidal neovascularization (CNV), also termed exudative or “wet” AMD, are common causes of blindness. The antidiabetic thiazolidinediones (TZDs), rosiglitazone, and troglitazone are PPARγ agonists with demonstrable antiproliferative, and anti-inflammatory effects, in vivo, were shown to ameliorate PDR and CNV in rodent models, implying the potential efficacy of TZDs for treating proliferative retinopathies in humans. Activation of the angiotensin II type 1 receptor (AT1-R) propagates proinflammatory and proliferative pathogenic determinants underlying PDR and CNV. The antihypertensive dual AT1-R blocker (ARB), telmisartan, recently was shown to activate PPARγ and improve glucose and lipid metabolism and to clinically improve PDR and CNV in rodent models. Therefore, the TZDs and telmisartan, clinically approved antidiabetic and antihypertensive drugs, respectively, may be efficacious for treating and attenuating PDR and CNV humans. Clinical trials are needed to test these possibilities.
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PPAR-gamma, Microglial Cells, and Ocular Inflammation: New Venues for Potential Therapeutic Approaches. PPAR Res 2011; 2008:295784. [PMID: 18382616 PMCID: PMC2276614 DOI: 10.1155/2008/295784] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2007] [Accepted: 01/25/2008] [Indexed: 01/06/2023] Open
Abstract
The last decade has witnessed an increasing interest for the role played by the peroxisome proliferator-activated receptor-γ (PPAR-γ) in controlling inflammation in peripheral organs as well as in the brain. Activation of PPAR-γ has been shown to control the response of microglial cells, the main macrophage population found in brain parenchyma, and limit the inflammation. The anti-inflammatory capacity of PPAR-γ agonists has led to the hypothesis that PPAR-γ might be targeted to modulate degenerative brain diseases in which inflammation has been increasingly recognized as a significant component. Recent experimental evidence suggests that PPAR-γ agonists could be exploited to treat ocular diseases such as diabetic retinopathy, age-related macular degeneration, autoimmune uveitis, and optic neuritis where inflammation has relevant role. Additional PPAR-γ agonist beneficial effects could involve amelioration of retinal microcirculation and inhibition of neovascularization. However, PPAR-γ activation could, in some instances, aggravate the ocular pathology, for example, by increasing the synthesis of vascular endothelial growth factor, a proangiogenic factor that could trigger a vicious circle and further deteriorate retinal perfusion. The development of new in vivo and in vitro models to study ocular inflammation and how to modulate for the eye benefit will be instrumental for the search of effective therapies.
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Abu El-Asrar AM, Al-Mezaine HS. Advances in the treatment of diabetic retinopathy. Saudi J Ophthalmol 2011; 25:113-22. [PMID: 23960912 PMCID: PMC3729319 DOI: 10.1016/j.sjopt.2011.01.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Accepted: 01/22/2011] [Indexed: 02/07/2023] Open
Abstract
Diabetic retinopathy, the most common long-term complication of diabetes mellitus, remains one of the leading causes of blindness worldwide. Strict metabolic control, tight blood pressure control, laser photocoagulation, and vitrectomy remain the standard care for diabetic retinopathy. Focal/grid photocoagulation is a better treatment than intravitreal triamcinolone acetonide in eyes with diabetic macular edema and should be considered as the first-line therapeutic option. The current evidence suggests that intravitreal triamcinolone acetonide or anti-vascular endothelial growth factor agents result in a temporary improvement of visual acuity and a short-term reduction in central macular thickness in patients with refractory diabetic macular edema and are an effective adjunctive treatments to laser photocoagulation or vitrectomy. However, triamcinolone is associated with risks of elevated intraocular pressure and cataract. Vitrectomy with the removal of the posterior hyaloid without internal limiting membrane peeling seems to be effective in eyes with persistent diffuse diabetic macular edema, particularly in eyes with associated vitreomacular traction. Emerging therapies include islet cell transplantation, fenofibrate, ruboxistaurin, pharmacologic vitreolysis, rennin-angiotensin system blockers, and peroxisome proliferator-activated receptor gamma agonists.
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Affiliation(s)
- Ahmed M. Abu El-Asrar
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
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Zhang JZ, Ward KW. WY-14 643, a Selective PPARα Agonist, Induces Proinflammatory and Proangiogenic Responses in Human Ocular Cells. Int J Toxicol 2010; 29:496-504. [DOI: 10.1177/1091581810376674] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Peroxisome proliferator-activated receptor α (PPARα) agonism in ocular inflammation has not been thoroughly investigated. The objective of this investigation was to determine the effect of WY-14 643, a selective PPARα agonist, on inflammatory cytokine release in human ocular cells. Stimulation of primary human corneal epithelial cells, keratocytes, and retinal endothelial cells with 1 to 10 ng/mL interleukin 1β (IL-1β) resulted in a significant increase in numerous inflammatory cytokines, including IL-6, IL-8, and tumor necrosis factor α (TNF-α); and dexamethasone was able to significantly inhibit these effects. However, WY-14 643 did not effectively block IL-1β-induced cytokine release in ocular cells; rather, significant increases in IL-1β-induced inflammatory cytokines were observed in these cells but not in aortic smooth muscle cells. WY-14 643 also significantly upregulated vascular endothelial growth factor (VEGF) expression in corneal epithelial cells and keratocytes. These studies demonstrate for the first time that PPARα agonism may be proinflammatory and proangiogenic in a variety of ocular cells and suggest that therapeutic applications of such agents in ophthalmology may be limited.
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Affiliation(s)
| | - Keith W. Ward
- Pharmaceutical R&D, Bausch & Lomb, Inc, Rochester, NY, USA
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Rao VR, Prescott E, Shelke NB, Trivedi R, Thomas P, Struble C, Gadek T, O'Neill CA, Kompella UB. Delivery of SAR 1118 to the retina via ophthalmic drops and its effectiveness in a rat streptozotocin (STZ) model of diabetic retinopathy (DR). Invest Ophthalmol Vis Sci 2010; 51:5198-204. [PMID: 20445119 DOI: 10.1167/iovs.09-5144] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
PURPOSE To determine the pharmacokinetics of SAR 1118, a small-molecule antagonist of leukocyte function-associated antigen (LFA)-1, after administration of ophthalmic drops in normal rats, and to determine its pharmacologic activity by assessing the inhibition of retinal leukostasis and vascular leakiness in a streptozotocin (STZ)-induced diabetic retinopathy model. METHODS The ocular pharmacokinetics of SAR 1118 were studied in rats after a single topical dose of (14)C-SAR 1118 (1 mg/eye; 40 μCi; 15.5 μL). SAR 1118 concentration time profiles in plasma and ocular tissues were quantified by liquid scintillation counting (LSC). The pharmacologic activity of SAR 1118 eye drops administered thrice daily for 2 months at 1% (0.3 mg/eye/d) and 5% (1.5 mg/eye/d) was assessed in an STZ-induced diabetic rat model by determining retinal leukostasis and blood-retinal barrier breakdown. Diabetic rats treated with periocularly administered celecoxib microparticles served as the positive control, and vehicle-treated rats served as the negative control. RESULTS A single dose of 6.5% (14)C-radiolabeled SAR 1118 ophthalmic drops delivered retinal drug levels greater than 1 μM in less than 30 minutes and sustained levels greater than 100 nM for 8 hours. SAR 1118 eye drops significantly reduced leukostasis and blood-retinal barrier breakdown in a dose-dependent manner. CONCLUSIONS SAR 1118 ophthalmic drops administered thrice daily deliver therapeutic levels of SAR 1118 in the retina and can alleviate the retinal complications associated with diabetes.
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Affiliation(s)
- Vidhya R Rao
- Department of Pharmaceutical Sciences, University of Colorado Denver, Aurora, Colorado 80045, USA
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Higuchi A, Ohashi K, Shibata R, Sono-Romanelli S, Walsh K, Ouchi N. Thiazolidinediones reduce pathological neovascularization in ischemic retina via an adiponectin-dependent mechanism. Arterioscler Thromb Vasc Biol 2009; 30:46-53. [PMID: 19910632 DOI: 10.1161/atvbaha.109.198465] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
UNLABELLED Background- The insulin-sensitizing agents referred to as thiazolidinediones (TZDs) possess antiatherogenic and anti-inflammatory actions that contribute to protection against diabetic macrovascular complications. However, little is known about the effects of TZDs on retinal microvessel disorders. OBJECTIVE To investigate whether TZDs modulate retinal vessel formation in a mouse model of oxygen-induced retinopathy. METHODS AND RESULTS Neonatal mice were subjected to ischemia-induced retinopathy to produce pathological neovascular tuft formation. Pioglitazone, 10 mg/kg per day, rosiglitazone, 10 mg/kg per day, or vehicle was given by gavage once a day from postnatal day 7 to postnatal day 17. Systemic treatment of wild-type (WT) mice with TZDs led to a significant decrease in pathological retinal neovascularization during ischemia compared with vehicle treatment, which was accompanied by increased plasma levels of the fat-derived hormone adiponectin (APN). In contrast to WT mice, TZDs had no effects on ischemia-induced pathological retinal vessel formation in APN-knockout (KO) mice. Pioglitazone reduced tumor necrosis factor (TNF) alpha expression in ischemic retina in WT mice but not in APN-KO mice. Furthermore, pioglitazone increased plasma APN levels in TNF-alpha-KO mice but did not affect ischemia-induced pathological retinal neovascularization in this strain. CONCLUSIONS These data show that TZDs attenuate pathological retinal microvessel formation through APN-mediated modulation of TNF-alpha production.
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Affiliation(s)
- Akiko Higuchi
- Molecular Cardiology/Whitaker Cardiovascular Institute, Boston University School of Medicine, 715 Albany St, W611, Boston, MA 02118, USA
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Effects of chronic PPAR-agonist treatment on cardiac structure and function, blood pressure, and kidney in healthy sprague-dawley rats. PPAR Res 2009; 2009:237865. [PMID: 19536351 PMCID: PMC2696219 DOI: 10.1155/2009/237865] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Revised: 02/25/2009] [Accepted: 03/23/2009] [Indexed: 01/02/2023] Open
Abstract
PPAR-γ agonists have been associated with heart failure (HF) in diabetic patients. These incidences have been reported mostly in patient populations who were at high risk for HF or had pre-existing impaired cardiovascular function. However, whether there are similar effects of these agents in subjects with no or reduced cardiovascular pathophysiology is not clear. In this study, the effects of chronic treatment with PD168, a potent peroxisome proliferator activated receptor (PPAR) subtype-γ agonist with weak activity at PPAR-α, and rosiglitazone (RGZ), a less potent PPAR-γ agonist with no PPAR-α activity, were evaluated on the cardiovascular-renal system in healthy male Sprague-Dawley (SD) rats by serial echocardiography and radiotelemetry. Rats were treated with vehicle (VEH), PD168, @ 10 or 50 mg/kg.bw/day (PD-10 or PD-50, resp.) or RGZ @ 180 mg/kg.bw/day for 28 days (n = 10/group). Relative to VEH, RGZ, and both doses of PD168 resulted in a significant fall in blood pressure. Furthermore, RGZ and PD168 increased plasma volume (% increase from baseline) 18%, 22%, and 48% for RGZ, PD-10, and PD-50, respectively. PD168 and RGZ significantly increased urinary aldosterone excretion and heart-to-body weight ratio relative to VEH. In addition, PD168 significantly decreased (10-16%) cardiac ejection fraction (EF) and increased left ventricular area (LVA) in systole (s) and diastole (d) in PD-10 and -50 rats. RGZ significantly increased LVAd; however, it did not affect EF relative to VEH. In conclusion, chronic PPAR-γ therapy may predispose the cardiorenal system to a potential sequela of structural and/or functional changes that may be deleterious with regard to morbidity and mortality.
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Zheng Z, Chen H, Ke G, Fan Y, Zou H, Sun X, Gu Q, Xu X, Ho PC. Protective effect of perindopril on diabetic retinopathy is associated with decreased vascular endothelial growth factor-to-pigment epithelium-derived factor ratio: involvement of a mitochondria-reactive oxygen species pathway. Diabetes 2009; 58:954-64. [PMID: 19188429 PMCID: PMC2661575 DOI: 10.2337/db07-1524] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECTIVE This study aimed to verify whether the decreased vascular endothelial growth factor (VEGF)-to-pigment epithelium-derived factor (PEDF) ratio can serve as an indicator for the protective effect of angiotensin-converting enzyme inhibitors (ACEIs) on diabetic retinopathy (DR) and to investigate the role of mitochondrial reactive oxygen species (ROS) in the downregulated VEGF-to-PEDF ratio. RESEARCH DESIGN AND METHODS Diabetic rats and control animals were randomly assigned to receive perindopril or vehicle for 24 weeks, and bovine retinal capillary endothelial cells (BRECs) were incubated with normal or high glucose with or without perindopril. VEGF, PEDF, PPARgamma, and uncoupling protein-2 (UCP-2) in the rat retinas or BREC extracts were examined by Western blotting and real-time RT-PCR. The levels of VEGF and PEDF in cell culture media were examined by ELISA. Mitochondrial membrane potential (Deltapsim) and ROS production were assayed using JC-1 or CM-H2DCFDA. RESULTS The VEGF-to-PEDF ratio was increased in the retina of diabetic rats; perindopril lowered the increased VEGF-to-PEDF ratio in diabetic rats and ameliorated the retinal damage. In BRECs, perindopril lowered the hyperglycemia-induced elevation of VEGF-to-PEDF ratio by reducing mitochondrial ROS. We found the decreased ROS production was a result of perindopril-induced upregulation of PPARgamma and UCP-2 expression and the subsequent decrease of Deltapsim. CONCLUSIONS It is concluded that the protective effect of ACEI on DR is associated with a decreased VEGF-to-PEDF ratio, which involves the mitochondria-ROS pathway through PPARgamma-mediated changes of UCP-2. This study paves a way for future application of ACEI in treatment of DR.
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Affiliation(s)
- Zhi Zheng
- Department of Ophthalmology, First People's Hospital of Shanghai, Shanghai Jiaotong University, Shanghai, China
| | - Haibing Chen
- Department of Endocrinology and Metabolism, the Sixth People's Hospital of Shanghai Affiliated to Shanghai Jiaotong University, Shanghai, China
| | - Genjie Ke
- Department of Ophthalmology, Anhui Provincial Hospital, Hefei, China
| | - Ying Fan
- Department of Ophthalmology, First People's Hospital of Shanghai, Shanghai Jiaotong University, Shanghai, China
| | - Haidong Zou
- Department of Ophthalmology, First People's Hospital of Shanghai, Shanghai Jiaotong University, Shanghai, China
| | - Xiaodong Sun
- Department of Ophthalmology, First People's Hospital of Shanghai, Shanghai Jiaotong University, Shanghai, China
| | - Qing Gu
- Department of Ophthalmology, First People's Hospital of Shanghai, Shanghai Jiaotong University, Shanghai, China
| | - Xun Xu
- Department of Ophthalmology, First People's Hospital of Shanghai, Shanghai Jiaotong University, Shanghai, China
- Corresponding author: Xun Xu,
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Huang W, Eum SY, András IE, Hennig B, Toborek M. PPARalpha and PPARgamma attenuate HIV-induced dysregulation of tight junction proteins by modulations of matrix metalloproteinase and proteasome activities. FASEB J 2009; 23:1596-606. [PMID: 19141539 DOI: 10.1096/fj.08-121624] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The blood-brain barrier (BBB) plays an important role in HIV trafficking into the brain and the development of the central nervous system complications in HIV infection. Tight junctions are the main structural and functional elements that regulate the BBB integrity. Exposure of human brain microvascular endothelial cells (hCMEC/D3 cell line) to HIV-infected monocytes resulted in decreased expression of tight junction proteins, such as junctional adhesion molecule-A (JAM)-A, occludin, and zonula occludens (ZO)-1. Control experiments involved exposure to uninfected monocytes. Alterations of tight junction protein expression were associated with increased endothelial permeability and elevated transendothelial migration of HIV-infected monocytes across an in vitro model of the BBB. Notably, overexpression of the peroxisome proliferator-activated receptor (PPAR)alpha or PPARgamma attenuated HIV-mediated dysregulation of tight junction proteins. With the use of exogenous PPARgamma agonists and silencing of PPARalpha or PPARgamma, these protective effects were connected to down-regulation of matrix metalloproteinase (MMP) and proteasome activities. Indeed, the HIV-induced decrease in the expression of JAM-A and occludin was restored by inhibition of MMP activity. Moreover, both MMP and proteasome inhibitors attenuated HIV-mediated altered expression of ZO-1. The present data indicate that down-regulation of MMP and proteasome activities constitutes a novel mechanism of PPAR-induced protections against HIV-induced disruption of brain endothelial cells.
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Affiliation(s)
- Wen Huang
- Molecular Neuroscience and Vascular Biology Laboratory, Department of Neurosurgery, University of Kentucky Medical Center, 593 Wethington Bldg., 900 S Limestone, Lexington, KY 40536, USA
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Characterization of a novel polymorphism in PPARG regulatory region associated with type 2 diabetes and diabetic retinopathy in Italy. J Biomed Biotechnol 2008; 2009:126917. [PMID: 19125195 PMCID: PMC2610251 DOI: 10.1155/2009/126917] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Revised: 09/11/2008] [Accepted: 11/01/2008] [Indexed: 12/21/2022] Open
Abstract
Peroxisome proliferator-activated receptor gamma polymorphisms have been widely associated with type 2 diabetes, although their role in the pathogenesis of vascular complications is not yet demonstrated. In this study, a cohort of 211 type 2 diabetes, 205 obese, and 254 control individuals was genotyped for Pro12Ala, C1431T, C-2821T polymorphisms, and for a newly identified polymorphism (A-2819G). The above-mentioned polymorphisms were analyzed by gene-specific PCR and direct sequencing of all samples. A significant difference was found for -2819G frequency when patients with type 2 diabetes—particularly diabetic women with the proliferative retinopathy—were compared with healthy control individuals. In conclusion, we identified a novel polymorphism, A-2819G, in PPARG gene, and we found it to be associated with type 2 diabetes and proliferative retinopathy in diabetic females. In the analyzed population, this variant represents a genetic risk factor for developing the diabetic retinopathy, whereas Pro12Ala and C1431T do not.
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Gardner TW, Antonetti DA. Novel potential mechanisms for diabetic macular edema: leveraging new investigational approaches. Curr Diab Rep 2008; 8:263-9. [PMID: 18631437 DOI: 10.1007/s11892-008-0047-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
This article evaluates the current knowledge of the molecular mechanisms by which diabetes ocular and systemic inflammation induce breakdown of the blood-retinal barrier resulting in macular edema. We also summarize the relationship between molecular targets and the use of therapeutic inhibitors in preclinical studies and clinical trials. Further studies are needed to understand the regulation of normal blood-retinal barrier physiology and the relationship between events in animal models of diabetic retinopathy and humans with diabetes.
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Affiliation(s)
- Thomas W Gardner
- Department of Ophthalmology, Penn State College of Medicine, HU19, 500 University Drive, Hershey, PA 17033, USA.
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Contributions of inflammatory processes to the development of the early stages of diabetic retinopathy. EXPERIMENTAL DIABETES RESEARCH 2008; 2007:95103. [PMID: 18274606 PMCID: PMC2216058 DOI: 10.1155/2007/95103] [Citation(s) in RCA: 450] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2007] [Accepted: 05/27/2007] [Indexed: 12/11/2022]
Abstract
Diabetes causes metabolic and physiologic abnormalities in the retina, and these changes suggest a role for inflammation in the development of diabetic retinopathy. These changes include upregulation of iNOS, COX-2, ICAM-1, caspase 1, VEGF, and NF-κB, increased production of nitric oxide, prostaglandin E2, IL-1β, and cytokines, as well as increased permeability and leukostasis. Using selective pharmacologic inhibitors or genetically modified animals, an increasing number of therapeutic approaches have been identified that significantly inhibit development of at least the early stages of diabetic retinopathy, especially occlusion and degeneration of retinal capillaries. A common feature of a number of these therapies is that they inhibit production of inflammatory mediators. The concept that localized inflammatory processes play a role in the development of diabetic retinopathy is relatively new, but evidence that supports the hypothesis is accumulating rapidly. This new hypothesis offers new insight into the pathogenesis of diabetic retinopathy, and offers novel targets to inhibit the ocular disease.
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Kim YH, Choi MY, Kim YS, Park CH, Lee JH, Chung IY, Yoo JM, Choi WS, Cho GJ, Kang SS. Triamcinolone acetonide protects the rat retina from STZ-induced acute inflammation and early vascular leakage. Life Sci 2007; 81:1167-73. [PMID: 17881007 DOI: 10.1016/j.lfs.2007.08.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Revised: 08/08/2007] [Accepted: 08/17/2007] [Indexed: 10/22/2022]
Abstract
Streptozotocin (STZ) has been commonly used to induce in vivo and in vitro hyperglycemic diabetes and its toxicity leads to inflammation and vascular injury. Triamcinolone acetonide (TA), as an anti-angiogenic/anti-inflammatory drug, is clinically used to improve the visual acuity in neovascular and edematous ocular diseases. The aim of this study was to investigate the effect of TA on early inflammation and vascular leakage in the retina of STZ-induced hyperglycemic rats. Hyperglycemia was induced in 8-week-old male Sprague-Dawley (SD) rats by a single intraperitoneal injection of STZ (65 mg/kg); only rats with blood glucose levels >13.9 mmol/l 1 day after STZ injection were included in STZ-hyperglycemic group. Sex- and age-matched SD rats injected with buffer were used as the control group. One day before STZ and buffer injection, 2 microl TA (4 mg/ml in saline) and 2 microl saline were intravitreal-injected into the right and the left eyes of rats, respectively. Retinal vascular leakage was measured using the Evans-blue method. Changes in pro-inflammatory target genes, such as tumor necrotic factor (TNF)-alpha, intracellular adhesion molecule (ICAM)-1, and vascular endothelial growth factor (VEGF) were assessed by immunoblottings, immunostaining, and ELISA analyses. Vascular hyperleakage and up-regulation of most pro-inflammatory genes peaked within a few days after STZ injection and had recovered. However, these changes were blocked by TA pretreatment. Our data suggest that TA controls STZ-induced early vascular leakage and temporary pro-inflammatory signals in the rat retina.
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Affiliation(s)
- Y H Kim
- Department of Anatomy and Neurobiology, Institute of Health Science, School of Medicine, Gyeongsang National University, Jinju, Gyeongnam 660-751, South Korea
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