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β-Adrenoreceptors as Therapeutic Targets for Ocular Tumors and Other Eye Diseases-Historical Aspects and Nowadays Understanding. Int J Mol Sci 2023; 24:ijms24054698. [PMID: 36902129 PMCID: PMC10003534 DOI: 10.3390/ijms24054698] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 02/21/2023] [Accepted: 02/24/2023] [Indexed: 03/05/2023] Open
Abstract
β-adrenoreceptors (ARs) are members of the superfamily of G-protein-coupled receptors (GPCRs), and are activated by catecholamines, such as epinephrine and norepinephrine. Three subtypes of β-ARs (β1, β2, and β3) have been identified with different distributions among ocular tissues. Importantly, β-ARs are an established target in the treatment of glaucoma. Moreover, β-adrenergic signaling has been associated with the development and progression of various tumor types. Hence, β-ARs are a potential therapeutic target for ocular neoplasms, such as ocular hemangioma and uveal melanoma. This review aims to discuss the expression and function of individual β-AR subtypes in ocular structures, as well as their role in the treatment of ocular diseases, including ocular tumors.
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The Role of Adrenoceptors in the Retina. Cells 2020; 9:cells9122594. [PMID: 33287335 PMCID: PMC7761662 DOI: 10.3390/cells9122594] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 11/29/2020] [Accepted: 12/01/2020] [Indexed: 01/16/2023] Open
Abstract
The retina is a part of the central nervous system, a thin multilayer with neuronal lamination, responsible for detecting, preprocessing, and sending visual information to the brain. Many retinal diseases are characterized by hemodynamic perturbations and neurodegeneration leading to vision loss and reduced quality of life. Since catecholamines and respective bindings sites have been characterized in the retina, we systematically reviewed the literature with regard to retinal expression, distribution and function of alpha1 (α1)-, alpha2 (α2)-, and beta (β)-adrenoceptors (ARs). Moreover, we discuss the role of the individual adrenoceptors as targets for the treatment of retinal diseases.
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Shi H, Ebrahim AS, Berger EA. A Contrast in Pathogenic Responses between C57BL/6J and BALB/cJ Mice Using a Model of Retinal Injury. THE AMERICAN JOURNAL OF PATHOLOGY 2018; 188:2717-2728. [PMID: 30236476 DOI: 10.1016/j.ajpath.2018.08.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 08/05/2018] [Accepted: 08/09/2018] [Indexed: 02/07/2023]
Abstract
Ischemia is associated with the pathogenesis of retinal disease, including diabetic retinopathy and glaucoma. As a result, the retinal ischemia/reperfusion injury model has been used to study neurovascular changes. Historically, murine models of retinal disease are established in C57BL/6J (B6) mice, which have been described as type 1-dominant responders. In bacterial keratitis models, B6 mice are susceptible, whereas BALB/cJ (BALB/c; type 2-dominant) mice exhibit a resistant phenotype. As such, we questioned whether the type 1/type 2 paradigm could be extrapolated to events associated with retinal pathogenesis. The current study compares the retinal response of B6 with BALB/c mice to investigate strain-specific differences. Retinas were collected at 2 and 10 days after ischemia/reperfusion injury to examine differences in neurovascular degeneration, leukostasis, oxidative stress, glial activation, and select inflammatory mediators. Although both strains showed signs of retinal injury, significantly more damage was observed in B6 mice. Retinal thickness was reduced and vascular damage was more severe in B6 mice. Exacerbated response to injury in B6 versus BALB/c retinas was further supported by increased leukostasis, inflammatory mediators, reactive oxygen species, and lipid peroxidation. In addition, more terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cells and increased glial activation were detected in B6 mice. These data indicate that B6 and BALB/c retinas differentially respond to injury, which has broader implications regarding the development and study of retinal diseases.
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Affiliation(s)
- Haoshen Shi
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan
| | - Abdul S Ebrahim
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan
| | - Elizabeth A Berger
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan.
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Liu L, Jiang Y, Curtiss E, Fukuchi KI, Steinle JJ. TLR4 regulates insulin-resistant proteins to increase apoptosis in the mouse retina. Inflamm Res 2017; 66:993-997. [PMID: 28681194 DOI: 10.1007/s00011-017-1080-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 06/14/2017] [Accepted: 06/28/2017] [Indexed: 12/28/2022] Open
Abstract
OBJECTIVE AND DESIGN Work in multiple organs has suggested that toll-like receptor 4 (TLR4) may play a role in insulin resistance. Additional studies have shown a negative role for TLR4 on retinal health. We have previously reported that β-adrenergic receptors can regulate both TLR4 signal transduction, as well as insulin signaling in the retina and in retinal endothelial cells. Thus, we hypothesized that TLR4 would regulate retinal insulin signaling. MATERIALS AND METHODS We used endothelial cell-specific TLR4 knockout mice, as well as TLR4-overexpressing mice for these studies. METHODS Western blotting and ELISA analyses were done for investigations of insulin receptor, insulin receptor substrate 1 (IRS-1) serine 307, and Akt phosphorylation, as well as cleaved caspase 3 levels in the mouse retina. RESULTS We found that loss of TLR4 led to increased insulin receptor and Akt phosphorylation, as well as decreased IRS-1Ser307 levels. In support of these results, TLR4 overexpression decreased insulin signaling and the cleavage of caspase 3. CONCLUSIONS Therefore, these results suggest that TLR4 plays a key role in insulin signaling in the retina. Reduction of TLR4 levels may be protective to the retina.
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Affiliation(s)
- Li Liu
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, 9314 Scott Hall, Detroit, MI, 48202, USA
| | - Youde Jiang
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, 9314 Scott Hall, Detroit, MI, 48202, USA
| | - Elizabeth Curtiss
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, 9314 Scott Hall, Detroit, MI, 48202, USA
| | - Ken-Ichiro Fukuchi
- Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, Peoria, IL, USA
| | - Jena J Steinle
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, 9314 Scott Hall, Detroit, MI, 48202, USA. .,Department of Ophthalmology, Wayne State University School of Medicine, Detroit, MI, USA.
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Lavine JA, Farnoodian M, Wang S, Darjatmoko SR, Wright LS, Gamm DM, Ip MS, Sorenson CM, Sheibani N. β2-Adrenergic Receptor Antagonism Attenuates CNV Through Inhibition of VEGF and IL-6 Expression. Invest Ophthalmol Vis Sci 2017; 58:299-308. [PMID: 28114591 PMCID: PMC5256681 DOI: 10.1167/iovs.16-20204] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Purpose The role of β–adrenergic receptor (AR) signaling in neovascular ocular diseases has recently emerged. We have previously reported that intraperitoneal propranolol inhibits choroidal neovascularization (CNV) in vivo and β2-AR blockade reduces vascular endothelial growth factor (VEGF) expression in mouse retinal pigment epithelium and choroidal endothelial cells in culture. Here we tested the hypothesis that the β2-AR regulates CNV through modulation of VEGF and inflammatory cytokine expression. Methods Mice were subjected to laser burns, inducing CNV, and were treated with an intravitreal β2-AR antagonist. After 3 and 5 days, total eye interleukin-6 (IL-6) and VEGF protein levels were measured, respectively. After 14 days, CNV was measured on choroidal–scleral flatmounts. The effects of β-AR signaling on VEGF and IL-6 expression were investigated in various mouse retinal and human RPE cells by using specific β-AR agonists and antagonists. Results β2–Adrenergic receptor signaling increased Vegf mRNA expression by approximately 3- to 4-fold in mouse retinal microglia and pericytes in culture. β2–Adrenergic receptor signaling upregulated IL-6 mRNA expression between 10- and 60-fold in mouse retinal microglia, pericytes, RPE, and choroidal endothelial cells in culture. Intravitreal injection of β2-AR antagonist ICI 118,551 reduced CNV by 35% and decreased IL-6 protein levels by approximately 50%. In primary human RPE cells, β2-AR activation also stimulated VEGF and IL-6 mRNA expression by 2- and 10-fold, respectively. Conclusions Anti-VEGF therapy for CNV is highly effective; however, some patients are resistant to therapy while others undergo repeated, frequent treatments. β2–Adrenergic receptor signaling is a potential therapeutic target because of its angiogenic and inflammatory properties.
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Affiliation(s)
- Jeremy A Lavine
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin, United States
| | - Mitra Farnoodian
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin, United States
| | - Shoujian Wang
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin, United States
| | - Soesiawati R Darjatmoko
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin, United States
| | - Lynda S Wright
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin, United States
| | - David M Gamm
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin, United States 2McPherson Eye Research Institute, University of Wisconsin, Madison, Wisconsin, United States
| | - Michael S Ip
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin, United States 2McPherson Eye Research Institute, University of Wisconsin, Madison, Wisconsin, United States
| | - Christine M Sorenson
- McPherson Eye Research Institute, University of Wisconsin, Madison, Wisconsin, United States
| | - Nader Sheibani
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin, United States 2McPherson Eye Research Institute, University of Wisconsin, Madison, Wisconsin, United States
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Garcia-Morales V, Friedrich J, Jorna LM, Campos-Toimil M, Hammes HP, Schmidt M, Krenning G. The microRNA-7-mediated reduction in EPAC-1 contributes to vascular endothelial permeability and eNOS uncoupling in murine experimental retinopathy. Acta Diabetol 2017; 54:581-591. [PMID: 28353063 PMCID: PMC5429352 DOI: 10.1007/s00592-017-0985-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Accepted: 03/16/2017] [Indexed: 01/08/2023]
Abstract
AIMS To investigate the consequences of oxidative stress and hypoxia on EPAC-1 expression during retinopathy. METHODS Oxygen-induced retinopathy was induced in mice and EPAC-1 expression investigated by immunofluorescence. In silico analyses were used to identify a link between EPAC-1 expression and microRNA-7-5p in endothelial cells and confirmed by western blot analyses on cells expressing microRNA-7-5p. In vitro, endothelial cells were either incubated at 2% oxygen or transfected with microRNA-7-5p, and the effects of these treatments on EPAC-1 expression, endothelial hyperpermeability and NO production were assessed. In the Ins2Akita mouse model, levels of EPAC-1 expression as well as microRNA-7-5p were assessed by qPCR. Endothelial nitric oxide synthase was assessed by immunoblotting in the Ins2Akita model. RESULTS Hypoxia induces the expression of microRNA-7-5p that translationally inhibits the expression of EPAC-1 in endothelial cells, resulting in hyperpermeability and the loss of eNOS activity. Activation of EPAC-1 by the cAMP analogue 8-pCPT-2'-O-Me-cAMP reduced the sensitivity of EPAC-1 to oxidative stress and restored the endothelial permeability to baseline levels. Additionally, 8-pCPT-2'-O-Me-cAMP rescued eNOS activity and NO production. In mouse models of retinopathy, i.e., oxygen-induced retinopathy and the spontaneous diabetic heterozygous Ins2Akita mice, EPAC-1 levels are decreased which is associated with an increase in microRNA-7-5p expression and reduced eNOS activity. CONCLUSION/INTERPRETATION In retinopathy, EPAC-1 expression is decreased in a microRNA-7-mediated manner, contributing to endothelial dysfunction. Pharmacological activation of remnant EPAC-1 rescues endothelial function. Collectively, these data indicate that EPAC-1 resembles an efficacious and druggable target molecule for the amelioration of (diabetic) retinopathy.
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Affiliation(s)
- Veronica Garcia-Morales
- Group of Research in Pharmacology of Chronic Diseases (CDPHARMA), Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela, 15782, Santiago de Compostela, Spain
- International Research and Training Network on Diabetic Microvascular Complications (GRK1874/DIAMICOM), University of Heidelberg, Heidelberg, Germany
- International Research and Training Network on Diabetic Microvascular Complications (GRK1874/DIAMICOM), University Medical Center Groningen, Groningen, The Netherlands
- Cardiovascular Regenerative Medicine (CAVAREM), Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Hanzeplein 1 (EA11), 9713 GZ, Groningen, The Netherlands
| | - Julian Friedrich
- International Research and Training Network on Diabetic Microvascular Complications (GRK1874/DIAMICOM), University of Heidelberg, Heidelberg, Germany
- International Research and Training Network on Diabetic Microvascular Complications (GRK1874/DIAMICOM), University Medical Center Groningen, Groningen, The Netherlands
- Cardiovascular Regenerative Medicine (CAVAREM), Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Hanzeplein 1 (EA11), 9713 GZ, Groningen, The Netherlands
- Section of Endocrinology, 5th Medical Department, Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Lysanne M Jorna
- Cardiovascular Regenerative Medicine (CAVAREM), Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Hanzeplein 1 (EA11), 9713 GZ, Groningen, The Netherlands
| | - Manuel Campos-Toimil
- Group of Research in Pharmacology of Chronic Diseases (CDPHARMA), Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela, 15782, Santiago de Compostela, Spain
| | - Hans-Peter Hammes
- International Research and Training Network on Diabetic Microvascular Complications (GRK1874/DIAMICOM), University of Heidelberg, Heidelberg, Germany
- International Research and Training Network on Diabetic Microvascular Complications (GRK1874/DIAMICOM), University Medical Center Groningen, Groningen, The Netherlands
- Section of Endocrinology, 5th Medical Department, Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Martina Schmidt
- International Research and Training Network on Diabetic Microvascular Complications (GRK1874/DIAMICOM), University of Heidelberg, Heidelberg, Germany
- International Research and Training Network on Diabetic Microvascular Complications (GRK1874/DIAMICOM), University Medical Center Groningen, Groningen, The Netherlands
- Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands
| | - Guido Krenning
- International Research and Training Network on Diabetic Microvascular Complications (GRK1874/DIAMICOM), University of Heidelberg, Heidelberg, Germany.
- International Research and Training Network on Diabetic Microvascular Complications (GRK1874/DIAMICOM), University Medical Center Groningen, Groningen, The Netherlands.
- Cardiovascular Regenerative Medicine (CAVAREM), Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Hanzeplein 1 (EA11), 9713 GZ, Groningen, The Netherlands.
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Liu L, Jiang Y, Chahine A, Curtiss E, Steinle JJ. Epac1 agonist decreased inflammatory proteins in retinal endothelial cells, and loss of Epac1 increased inflammatory proteins in the retinal vasculature of mice. Mol Vis 2017; 23:1-7. [PMID: 28210097 PMCID: PMC5287445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 01/23/2017] [Indexed: 10/25/2022] Open
Abstract
PURPOSE Increased inflammatory mediator levels are reported in diabetic retinopathy. We previously reported that β-adrenergic receptor agonists reduced inflammatory mediators in the diabetic retina; however, these agents cannot be given systemically. Here, we investigated whether Epac1 is key to the protective effects of β-adrenergic receptor agonists. METHODS We cultured primary human retinal endothelial cells (RECs) in normal (5 mM) or high (25 mM) glucose and treated them with an Epac1-specific agonist. Additionally, we generated Epac1 conditional vascular endothelial cell knockout mice by breeding Epac1 floxed mice with Cdh5 Cre mice to investigate the role of Epac1 in the retinal levels of tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), nuclear factor kappa beta (NFκB), and inhibitor of kappa beta (IκB). Confocal microscopy was performed to localize Epac1 in the mouse retina. RESULTS Data showed that high glucose increased the TNF-α and IL-1β levels in the RECs, which were reduced cells treated with the Epac1 agonist. The loss of Epac1 in the retinas of the conditional knockout mice resulted in statistically significantly increased levels of TNF-α and IL-1β, as well as NFκB. CONCLUSIONS These data indicate that Epac1 may be protective to the retina through inhibition of key inflammatory mediators.
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Affiliation(s)
- Li Liu
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI
| | - Youde Jiang
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI
| | - Adam Chahine
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI
| | - Elizabeth Curtiss
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI
| | - Jena J. Steinle
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI,Department of Ophthalmology, Wayne State University School of Medicine, Detroit, MI
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Roy S, Kern TS, Song B, Stuebe C. Mechanistic Insights into Pathological Changes in the Diabetic Retina: Implications for Targeting Diabetic Retinopathy. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 187:9-19. [PMID: 27846381 DOI: 10.1016/j.ajpath.2016.08.022] [Citation(s) in RCA: 145] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 07/27/2016] [Accepted: 08/04/2016] [Indexed: 12/16/2022]
Abstract
Increasing evidence points to inflammation as one of the key players in diabetes-mediating adverse effects to the neuronal and vascular components of the retina. Sustained inflammation induces biochemical and molecular changes, ultimately contributing to retinal complications and vision loss in diabetic retinopathy. In this review, we describe changes involving metabolic abnormalities secondary to hyperglycemia, oxidative stress, and activation of transcription factors, together with neuroglial alterations in the diabetic retina. Changes in biochemical pathways and how they promote pathophysiologic developments involving proinflammatory cytokines, chemokines, and adhesion molecules are discussed. Inflammation-mediated leukostasis, retinal ischemia, and neovascularization and their contribution to pathological and clinical stages leading to vision loss in diabetic retinopathy (DR) are highlighted. In addition, potential treatment strategies involving fibrates, connexins, neuroprotectants, photobiomodulation, and anti-inflammatory agents against the development and progression of DR lesions are reviewed. The importance of appropriate animal models for testing novel strategies against DR lesions is discussed; in particular, a novel nonhuman primate model of DR and the suitability of rodent models are weighed. The purpose of this review is to highlight our current understanding of the pathogenesis of DR and to summarize recent advances using novel approaches or targets to investigate and inhibit the retinopathy.
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Affiliation(s)
- Sayon Roy
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts; Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts.
| | - Timothy S Kern
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio; Department of Clinical and Molecular Endocrinology, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Brian Song
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts; Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts
| | - Caren Stuebe
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts; Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts
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Shi Y, Shu ZJ, Xue X, Yeh CK, Katz MS, Kamat A. β2-Adrenergic receptor ablation modulates hepatic lipid accumulation and glucose tolerance in aging mice. Exp Gerontol 2016; 78:32-8. [PMID: 26952573 DOI: 10.1016/j.exger.2016.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 03/02/2016] [Accepted: 03/03/2016] [Indexed: 01/10/2023]
Abstract
Catecholamines acting through β-adrenergic receptors (β(1)-, β(2)-, β(3)-AR subtypes) modulate important biological responses in various tissues. Our previous studies suggest a role for increased hepatic β-AR-mediated signaling during aging as a mediator of hepatic steatosis, liver glucose output, and insulin resistance in rodents. In the current study, we have utilized β(2)-AR knockout (KO) and wildtype (WT) control mice to define further the role of β(2)-AR signaling during aging on lipid and glucose metabolism. Our results demonstrate for the first time that age-related increases in hepatic triglyceride accumulation and body weight are attenuated upon β(2)-AR ablation. Although no differences in plasma triglyceride, non-esterified fatty acids or insulin levels were detected between old WT and KO animals, an age-associated increase in hepatic expression of lipid homeostasis regulator Cidea was significantly reduced in old KO mice. Interestingly, we also observed a shift from reduced glucose tolerance in young adult KO animals to significantly improved glucose tolerance in old KO when compared to age-matched WT mice. These results provide evidence for an important role played by β(2)-ARs in the regulation of lipid and glucose metabolism during aging. The effect of β(2)-AR ablation on caloric intake during aging is currently not known and requires investigation. Future studies are also warranted to delineate the β(2)-AR-mediated mechanisms involved in the control of lipid and glucose homeostasis, especially in the context of a growing aging population.
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Affiliation(s)
- Yun Shi
- Geriatric Research, Education and Clinical Center, Audie L. Murphy Division, South Texas Veterans Health Care System, San Antonio, TX 78229, USA; Department of Medicine, University of Texas Health Science Center at San Antonio, TX 78229, USA.
| | - Zhen-Ju Shu
- Geriatric Research, Education and Clinical Center, Audie L. Murphy Division, South Texas Veterans Health Care System, San Antonio, TX 78229, USA; Department of Medicine, University of Texas Health Science Center at San Antonio, TX 78229, USA.
| | - Xiaoling Xue
- Geriatric Research, Education and Clinical Center, Audie L. Murphy Division, South Texas Veterans Health Care System, San Antonio, TX 78229, USA; Department of Medicine, University of Texas Health Science Center at San Antonio, TX 78229, USA.
| | - Chih-Ko Yeh
- Geriatric Research, Education and Clinical Center, Audie L. Murphy Division, South Texas Veterans Health Care System, San Antonio, TX 78229, USA; Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, TX 78229, USA; Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, TX 78229, USA.
| | - Michael S Katz
- Geriatric Research, Education and Clinical Center, Audie L. Murphy Division, South Texas Veterans Health Care System, San Antonio, TX 78229, USA; Department of Medicine, University of Texas Health Science Center at San Antonio, TX 78229, USA; Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, TX 78229, USA.
| | - Amrita Kamat
- Geriatric Research, Education and Clinical Center, Audie L. Murphy Division, South Texas Veterans Health Care System, San Antonio, TX 78229, USA; Department of Medicine, University of Texas Health Science Center at San Antonio, TX 78229, USA; Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, TX 78229, USA.
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10
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Jiang Y, Thakran S, Bheemreddy R, Coppess W, Walker RJ, Steinle JJ. Sodium salicylate reduced insulin resistance in the retina of a type 2 diabetic rat model. PLoS One 2015; 10:e0125505. [PMID: 25874611 PMCID: PMC4397086 DOI: 10.1371/journal.pone.0125505] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 03/22/2015] [Indexed: 01/04/2023] Open
Abstract
Sodium salicylate has been reported to reduce markers of diabetic retinopathy in a type 1 rat model. Because rates of type 2 diabetes are on the rise, we wanted to determine whether salicylate could improve insulin resistance in a type 2 rat model, as well as improve retinal function. We treated lean and obese BBZDR/Wor type 2 diabetic rats with salicylate in their chow for 2 months. Prior to salicylate treatment, rats underwent an electroretinogram to measure retinal function. After 2 months of treatment, rats underwent an additional electroretinogram prior to sacrifice. In addition to the animal model, we also treated retinal endothelial cells (REC) and rat Müller cells with salicylate and performed the same analyses as done for the rat retinal lysates. To investigate the role of salicylate in insulin signaling, we measured TNFα and caspase 3 levels by ELISA, as well as performed Western blotting for insulin receptor substrate 1, insulin receptor, SOCS3, and pro- and anti-apoptotic markers. Data demonstrated that salicylate significantly improved retinal function, as well as reduced TNFα and SOCS3-induced insulin resistance in all samples. Overall, results suggest that salicylate is effective in reducing insulin resistance in the retina of type 2 diabetic rat models.
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Affiliation(s)
- Youde Jiang
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, Michigan, United States of America
- VA Medical Center, Memphis, Tennessee, United States of America
| | - Shalini Thakran
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Rajini Bheemreddy
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - William Coppess
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Robert J. Walker
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
- Philder Smith College, Little Rock, Arkansas, United States of America
| | - Jena J. Steinle
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, Michigan, United States of America
- Department of Ophthalmology, Wayne State University, Detroit, Michigan, United States of America
- VA Medical Center, Memphis, Tennessee, United States of America
- * E-mail:
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Du Y, Cramer M, Lee CA, Tang J, Muthusamy A, Antonetti DA, Jin H, Palczewski K, Kern TS. Adrenergic and serotonin receptors affect retinal superoxide generation in diabetic mice: relationship to capillary degeneration and permeability. FASEB J 2015; 29:2194-204. [PMID: 25667222 DOI: 10.1096/fj.14-269431] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 01/13/2015] [Indexed: 12/22/2022]
Abstract
Reactive oxygen species play an important role in the pathogenesis of diabetic retinopathy. We studied the role of adrenergic and serotonin receptors in the generation of superoxide by retina and 661W retinal cells in high glucose and of the α1-adrenergic receptor (AR) on vascular lesions of the retinopathy in experimentally diabetic C57Bl/6J mice (and controls) after 2 and 8 months. Compared with 5 mM glucose, incubating cells or retinal explants in 30 mM glucose induced superoxide generation. This response was reduced or ablated by pharmacologic inhibition of the α1-AR (a Gq-coupled receptor) or Gs-coupled serotonin (5-HT2, 5-HT4, 5-HT6, and 5-HT7) receptors or by activation of the Gi-coupled α2-AR. In elevated glucose, the α1-AR produced superoxide via phospholipase C, inositol triphosphate-induced Ca(2+) release, and NADPH oxidase, and pharmacologic inhibition of these reactions prevented the superoxide increase. Generation of retinal superoxide, expression of proinflammatory proteins, and degeneration of retinal capillaries in diabetes all were significantly inhibited with daily doxazosin or apocynin (inhibitors of α1-AR and NADPH oxidase, respectively), but increased vascular permeability was not significantly affected. Adrenergic receptors, and perhaps other GPCRs, represent novel targets for inhibiting the development of important features of diabetic retinopathy.
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Affiliation(s)
- Yunpeng Du
- *Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Department of Ophthalmology and Visual Sciences, The University of Michigan, Ann Arbor, Michigan, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA; and Veterans Administration Medical Center Research Service 151, Cleveland, Ohio, USA
| | - Megan Cramer
- *Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Department of Ophthalmology and Visual Sciences, The University of Michigan, Ann Arbor, Michigan, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA; and Veterans Administration Medical Center Research Service 151, Cleveland, Ohio, USA
| | - Chieh Allen Lee
- *Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Department of Ophthalmology and Visual Sciences, The University of Michigan, Ann Arbor, Michigan, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA; and Veterans Administration Medical Center Research Service 151, Cleveland, Ohio, USA
| | - Jie Tang
- *Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Department of Ophthalmology and Visual Sciences, The University of Michigan, Ann Arbor, Michigan, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA; and Veterans Administration Medical Center Research Service 151, Cleveland, Ohio, USA
| | - Arivalagan Muthusamy
- *Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Department of Ophthalmology and Visual Sciences, The University of Michigan, Ann Arbor, Michigan, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA; and Veterans Administration Medical Center Research Service 151, Cleveland, Ohio, USA
| | - David A Antonetti
- *Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Department of Ophthalmology and Visual Sciences, The University of Michigan, Ann Arbor, Michigan, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA; and Veterans Administration Medical Center Research Service 151, Cleveland, Ohio, USA
| | - Hui Jin
- *Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Department of Ophthalmology and Visual Sciences, The University of Michigan, Ann Arbor, Michigan, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA; and Veterans Administration Medical Center Research Service 151, Cleveland, Ohio, USA
| | - Krzysztof Palczewski
- *Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Department of Ophthalmology and Visual Sciences, The University of Michigan, Ann Arbor, Michigan, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA; and Veterans Administration Medical Center Research Service 151, Cleveland, Ohio, USA
| | - Timothy S Kern
- *Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Department of Ophthalmology and Visual Sciences, The University of Michigan, Ann Arbor, Michigan, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA; and Veterans Administration Medical Center Research Service 151, Cleveland, Ohio, USA
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12
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Jiang Y, Zhang Q, Steinle JJ. Beta-adrenergic receptor agonist decreases VEGF levels through altered eNOS and PKC signaling in diabetic retina. Growth Factors 2015; 33:192-9. [PMID: 26115368 PMCID: PMC4791949 DOI: 10.3109/08977194.2015.1054990] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Vascular endothelial cell growth factor (VEGF) is increased in diabetic macular edema. Compound 49b, a novel β-adrenergic receptor agonist, is protective in a type 1 diabetic rat model. We questioned whether Compound 49b could decrease VEGF levels, suggesting that Compound 49b may be effective against edema. Two-month diabetic rats received topical Compound 49b for 7 days only and/or insulin-like growth factor binding protein 3 (IGFBP-3) siRNA. We also measured endothelial nitric oxide synthase (eNOS) and protein kinase C (PKC)ζ and PKCδ phosphorylation. Retinal endothelial cells (RECs) cultured in high glucose were treated with Compound 49b and IGFBP-3 siRNA for evaluation of the same signaling pathways. Compound 49b significantly decreased VEGF through increased IGFBP-3 in the diabetic retina. Compound 49b also reduced eNOS, PKCζ and PKCδ phosphorylation in the diabetic retina and REC. Compound 49b regulated a number of proteins involved in REC barrier properties.
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Affiliation(s)
- Youde Jiang
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, MI, USA
| | - Qiuhua Zhang
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Jena J. Steinle
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, MI, USA
- Department of Ophthalmology, Wayne State University, Detroit, MI, USA
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13
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The β-adrenergic system as a possible new target for pharmacologic treatment of neovascular retinal diseases. Prog Retin Eye Res 2014; 42:103-29. [DOI: 10.1016/j.preteyeres.2014.06.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 05/30/2014] [Accepted: 06/05/2014] [Indexed: 12/31/2022]
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14
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Jiang Y, Zhang Q, Ye EA, Steinle JJ. Etanercept restores normal insulin signal transduction in β2-adrenergic receptor knockout mice. J Neuroinflammation 2014; 11:137. [PMID: 25138272 PMCID: PMC4149274 DOI: 10.1186/s12974-014-0137-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 07/27/2014] [Indexed: 11/12/2022] Open
Abstract
Background Inhibition of TNFα protects the retina against diabetic-like changes in rodent models. The mechanism by which TNFα induces deleterious retinal changes is not known. Previously, we have shown that TNFα can inhibit normal insulin signal transduction, leading to increased apoptosis in both retinal endothelial cells (REC) and Müller cells. Additionally, β2-adrenergic receptor knockout mice (β2KO) have increased TNFα levels and decreased insulin receptor activity. In this study, we hypothesized that inhibition of TNFα in β2KO mice would increase normal insulin signaling, leading to improved retinal function. Methods C57BL6 or β2KO mice were left untreated or treated with etanercept (0.3 mg/kg subcutaneously, 3× a week) for 2 months. Electroretinogram analyses were done before treatment was initiated and after two months of treatment with etanercept on all mice. Western blot or ELISA analyses were done on whole retinal lysates from all four groups of mice for TNFα, suppressor of cytokine signaling 3 (SOCS3), insulin receptor, and apoptotic proteins. Results Etanercept significantly reduced TNFα levels in β2KO mice, leading to increased insulin receptor phosphorylation on tyrosine 1150/1151. SOCS3 levels were increased in β2KO mice, which were reduced after etanercept treatment. Pro-apoptotic proteins were reduced in etanercept-treated β2KO mice. Etanercept improved ERG amplitudes in β2KO mice. Conclusions Inhibition of TNFα by etanercept protects the retina likely through reduced TNFα-mediated insulin resistance, leading to reduced apoptosis.
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Affiliation(s)
| | | | | | - Jena J Steinle
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN, USA.
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15
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Jiang Y, Thakran S, Bheemreddy R, Ye EA, He H, Walker RJ, Steinle JJ. Pioglitazone normalizes insulin signaling in the diabetic rat retina through reduction in tumor necrosis factor α and suppressor of cytokine signaling 3. J Biol Chem 2014; 289:26395-26405. [PMID: 25086044 DOI: 10.1074/jbc.m114.583880] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Dysfunctional insulin signaling is a key component of type 2 diabetes. Little is understood of the effects of systemic diabetes on retinal insulin signaling. A number of agents are used to treat patients with type 2 diabetes to normalize glucose levels and improve insulin signaling; however, little has been done to investigate the effects of these agents on retinal insulin signal transduction. We hypothesized that pioglitazone, a peroxisome proliferator-activated receptor γ (PPARγ) agonist, would normalize retinal insulin signal transduction through reduced tumor necrosis factor α (TNFα) and suppressor of cytokine signaling 3 (SOCS3) activities in whole retina and retinal endothelial cells (REC) and Müller cells. To test this hypothesis, we used the BBZDR/Wor type 2 diabetic rat model, as well as REC and Müller cells cultured in normoglycemia and hyperglycemic conditions, to investigate the effects of pioglitazone on TNFα, SOCS3, and downstream insulin signal transduction proteins. We also evaluated pioglitazone's effects on retinal function using electroretinogram and markers of apoptosis. Data demonstrate that 2 months of pioglitazone significantly increased electroretinogram amplitudes in type 2 diabetic obese rats, which was associated with improved insulin receptor activation. These changes occurred in both REC and Müller cells treated with pioglitazone, suggesting that these two cell types are key to insulin resistance in the retina. Taken together, these data provide evidence of impaired insulin signaling in type 2 diabetes rats, which was improved by increasing PPARγ activity. Further investigations of PPARγ actions in the retina may provide improved treatment options.
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Affiliation(s)
- Youde Jiang
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Shalini Thakran
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Rajini Bheemreddy
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Eun-Ah Ye
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Hui He
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, Tennessee 38163 and
| | - Robert J Walker
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee 38163; Department of Biology, Philander Smith College, Little Rock, Arkansas 72202
| | - Jena J Steinle
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee 38163; Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, Tennessee 38163 and; Department of Anatomy and Neurobiology, and University of Tennessee Health Science Center, Memphis, Tennessee 38163.
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16
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Zhang Q, Soderland D, Steinle JJ. TNFα inhibits IGFBP-3 through activation of p38α and casein kinase 2 in human retinal endothelial cells. PLoS One 2014; 9:e103578. [PMID: 25073020 PMCID: PMC4114743 DOI: 10.1371/journal.pone.0103578] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Accepted: 07/02/2014] [Indexed: 01/31/2023] Open
Abstract
We recently reported a reciprocal relationship between tumor necrosis factor alpha (TNFα) and insulin-like receptor growth factor binding protein 3 (IGFBP-3) in whole retina of normal and IGFBP-3 knockout mice. A similar relationship was also observed in cultured retinal endothelial cells (REC). We found that TNFα significantly reduced IGFBP-3 levels and vice-versa, IGFBP-3 can lower TNFα and TNFα receptor expression. Since IGFBP-3 is protective to the diabetic retina and TNFα is causative in the development of diabetic retinopathy, we wanted to better understand the cellular mechanisms by which TNFα can reduce IGFBP-3 levels. For these studies, primary human retinal endothelial cells (REC) were used since these cells undergo TNFα-mediated apoptosis under conditions of high glucose conditions and contribute to diabetic retinopathy. We first cultured REC in normal or high glucose, treated with exogenous TNFα, then measured changes in potential signaling pathways, with a focus on P38 mitogen-activated protein kinase alpha (P38α) and casein kinase 2 (CK2) as these pathways have been linked to both TNFα and IGFBP-3. We found that TNFα significantly increased phosphorylation of P38α and CK2. Furthermore, specific inhibitors of P38α or CK2 blocked TNFα inhibition of IGFBP-3 expression, demonstrating that TNFα reduces IGFBP-3 through activation of P38α and CK2. Since TNFα and IGFBP-3 are key mediators of retinal damage and protection respectively in diabetic retinopathy, increased understanding of the relationship between these two proteins will offer new therapeutic options for treatment.
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Affiliation(s)
- Qiuhua Zhang
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Dylan Soderland
- Cell Systems Corp, Kirkland, Washington, United States of America
| | - Jena J. Steinle
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
- * E-mail:
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17
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Jiang Y, Zhang Q, Ye EA, Steinle JJ. β1-adrenergic receptor stimulation by agonist Compound 49b restores insulin receptor signal transduction in vivo. Mol Vis 2014; 20:872-80. [PMID: 24966659 PMCID: PMC4067233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 06/19/2014] [Indexed: 11/18/2022] Open
Abstract
PURPOSE Determine whether Compound 49b treatment ameliorates retinal changes due to the lack of β2-adrenergic receptor signaling. METHODS Using retinas from 3-month-old β2-adrenergic receptor-deficient mice, we treated mice with our novel β1-/β2-adrenergic receptor agonist, Compound 49b, to assess the effects of adrenergic agonists acting only on β1-adrenergic receptors due to the absence of β2-adrenergic receptors. Western blotting or enzyme-linked immunosorbent assay (ELISA) analyses were performed for β1- and β2-adrenergic receptors, as well as key insulin resistance proteins, including TNF-α, SOCS3, IRS-1(Ser307), and IR(Tyr960). Analyses were also performed on key anti- and proapoptotic proteins: Akt, Bcl-xL, Bax, and caspase 3. Electroretinogram analyses were conducted to assess functional changes, while histological assessment was conducted for changes in retinal thickness. RESULTS A 2-month treatment of β2-adrenergic receptor-deficient mice with daily eye drops of 1 mM Compound 49b, a novel β1- and β2-adrenergic receptor agonist, reversed the changes in insulin resistance markers (TNF-α and SOCS3) observed in untreated β2-adrenergic receptor-deficient mice, and concomitantly increased morphological integrity (retinal thickness) and functional responses (electroretinogram amplitude). These results suggest that stimulating β1-adrenergic receptors on retinal endothelial cells or Müller cells can compensate for the loss of β2-adrenergic receptor signaling on Müller cells, restore insulin signal transduction, reduce retinal apoptosis, and enhance retinal function. CONCLUSIONS Since our previous studies with β1-adrenergic receptor knockout mice confirmed that the reverse also occurs (β2-adrenergic receptor stimulation can compensate for the loss of β1-adrenergic receptor activity), it appears that increased activity in either of these pathways alone is sufficient to block insulin resistance-based retinal cell apoptosis.
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Affiliation(s)
- Youde Jiang
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN
| | - Qiuhua Zhang
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN
| | - Eun-Ah Ye
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN
| | - Jena J. Steinle
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN,Department of Anatomy/Neurobiology, University of Tennessee Health Science Center, Memphis, TN,Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, TN
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18
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Jiang Y, Zhang Q, Steinle JJ. Intravitreal injection of IGFBP-3 restores normal insulin signaling in diabetic rat retina. PLoS One 2014; 9:e93788. [PMID: 24695399 PMCID: PMC3973588 DOI: 10.1371/journal.pone.0093788] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 03/07/2014] [Indexed: 11/18/2022] Open
Abstract
Diabetes-induced changes in growth factor binding protein 3 (IGFBP-3) and tumor necrosis factor alpha (TNFα) have been linked to decreased insulin receptor signaling in diabetic retinopathy. Our previous studies in retinas of diabetic rats have shown that Compound 49b, a novel β-adrenergic receptor agonist, prevented diabetic changes by increasing IGFBP-3 and decreasing TNFα, thus restoring insulin signaling and protection against diabetic retinopathy. The current study was designed to determine whether boosted expression of IGFBP-3 NB (a non-IGF-1 binding form of IGFBP-3) alone is sufficient to mimic the full actions of Compound 49b in protecting against diabetic retinopathy, as well as testing whether IGFBP-3 NB is linked to a restoration of normal insulin signal transduction. Two months after initiation of streptozotocin-induced diabetes, rats received a single intravitreal injection of IGFBP-3 NB plasmid in the right eye. Four days after injection, electroretinogram (ERG) analyses were performed prior to sacrifice. Whole retinal lysates from control, diabetic, diabetic + control plasmid, and diabetic+ IGFBP-3 NB were analyzed for IGFBP-3, TNFα, suppressor of cytokine signaling 3 (SOCS3), and insulin receptor signaling partners using Western blotting or ELISA. Data show that a single intraocular injection of IGFBP-3 NB in diabetic animals significantly reduced TNFα levels, concomitant with reductions in IRS-1Ser307, SOCS3, and pro-apoptotic markers, while restoring insulin receptor phosphorylation and increasing anti-apoptotic marker levels. These cellular changes were linked to restoration of retinal function. Our findings establish IGFBP-3 as a pivotal regulator of the insulin receptor/TNFα pathway and a potential therapeutic target for diabetic retinopathy.
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Affiliation(s)
- Youde Jiang
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Qiuhua Zhang
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Jena J. Steinle
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
- Department of Anatomy & Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
- * E-mail:
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