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Watkins WM, McCollum GW, Savage SR, Capozzi ME, Penn JS, Morrison DG. Hypoxia-induced expression of VEGF splice variants and protein in four retinal cell types. Exp Eye Res 2013; 116:240-6. [PMID: 24076411 DOI: 10.1016/j.exer.2013.09.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 09/12/2013] [Accepted: 09/17/2013] [Indexed: 12/20/2022]
Abstract
The purpose of this study was to investigate the hypoxia-induced Vegf120, Vegf164 and Vegf188 mRNA expression profiles in rat Müller cells (MC), astrocytes, retinal pigmented epithelial cells (RPE) and retinal microvascular endothelial cells (RMEC) and correlate these findings to VEGF secreted protein. Cultured cells were exposed to normoxia or hypoxia. Total RNA was isolated from cell lysates and Vegf splice variant mRNA copy numbers were assayed by a validated qRT-PCR external calibration curve method. mRNA copy numbers were normalized to input total RNA. Conditioned medium was collected from cells and assayed for total VEGF protein by ELISA. Hypoxia increased total Vegf mRNA and secreted protein in all the retinal cell types, with the highest levels observed in MC and astrocytes ranking second. Total Vegf mRNA levels in hypoxic RPE and RMEC were comparable; however, the greatest hypoxic induction of each Vegf splice variant mRNA was observed in RMEC. RPE and RMEC ranked 3rd and 4th respectively, in terms of secreted total VEGF protein in hypoxia. The Vegf120, Vegf164 and Vegf188 mRNA splice variants were all increased in hypoxic cells compared to normoxic controls. In normoxia, the relative Vegf splice variant mRNA levels ranked from highest to lowest for each cell type were Vegf164 > Vegf120 > Vegf188. Hypoxic induction did not alter this ranking, although it did favor an increased stoichiometry of Vegf164 mRNA over the other two splice variants. MC and astrocytes are likely to be the major sources of total Vegf, Vegf164 splice variant mRNAs, and VEGF protein in retinal hypoxia.
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Affiliation(s)
- William M Watkins
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, 8009 Medical Center East, 1215 21st Avenue South, Nashville, TN 37232-8808, USA
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253
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Jo DH, Cho CS, Kim JH, Jun HO, Kim JH. Animal models of diabetic retinopathy: doors to investigate pathogenesis and potential therapeutics. J Biomed Sci 2013; 20:38. [PMID: 23786217 PMCID: PMC3694455 DOI: 10.1186/1423-0127-20-38] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Accepted: 06/17/2013] [Indexed: 12/20/2022] Open
Abstract
Effective and validated animal models are valuable to investigate the pathogenesis and potential therapeutics for human diseases. There is much concern for diabetic retinopathy (DR) in that it affects substantial number of working population all around the world, resulting in visual deterioration and social deprivation. In this review, we discuss animal models of DR based on different species of animals from zebrafish to monkeys and prerequisites for animal models. Despite criticisms on imprudent use of laboratory animals, we hope that animal models of DR will be appropriately utilized to deepen our understanding on the pathogenesis of DR and to support our struggle to find novel therapeutics against catastrophic visual loss from DR.
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Affiliation(s)
- Dong Hyun Jo
- Fight against Angiogenesis-Related Blindness (FARB) Laboratory, Clinical Research Institute, Seoul National University, Seoul 110-744, Republic of Korea
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254
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Vadlapatla RK, Vadlapudi AD, Mitra AK. Hypoxia-inducible factor-1 (HIF-1): a potential target for intervention in ocular neovascular diseases. Curr Drug Targets 2013; 14:919-35. [PMID: 23701276 DOI: 10.2174/13894501113149990015] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2013] [Accepted: 05/20/2013] [Indexed: 12/29/2022]
Abstract
Constant oxygen supply is essential for proper tissue development, homeostasis and function of all eukaryotic organisms. Cellular response to reduced oxygen levels is mediated by the transcriptional regulator hypoxia-inducible factor-1 (HIF-1). It is a heterodimeric complex protein consisting of an oxygen dependent subunit (HIF-1α) and a constitutively expressed nuclear subunit (HIF-1β). In normoxic conditions, de novo synthesized cytoplasmic HIF-1α is degraded by 26S proteasome. Under hypoxic conditions, HIF-1α is stabilized, binds with HIF-1β and activates transcription of various target genes. These genes play a key role in regulating angiogenesis, cell survival, proliferation, chemotherapy, radiation resistance, invasion, metastasis, genetic instability, immortalization, immune evasion, metabolism and stem cell maintenance. This review highlights the importance of hypoxia signaling in development and progression of various vision threatening pathologies such as diabetic retinopathy, retinopathy of prematurity, age-related macular degeneration and glaucoma. Further, various inhibitors of HIF-1 pathway that may have a viable potential in the treatment of oxygen-dependent ocular diseases are also discussed.
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Affiliation(s)
- Ramya Krishna Vadlapatla
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 2464 Charlotte Street, Kansas City, MO 64108-2718, USA
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255
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Luo L, Zhang X, Hirano Y, Tyagi P, Barabás P, Uehara H, Miya TR, Singh N, Archer B, Qazi Y, Jackman K, Das SK, Olsen T, Chennamaneni SR, Stagg BC, Ahmed F, Emerson L, Zygmunt K, Whitaker R, Mamalis C, Huang W, Gao G, Srinivas SP, Krizaj D, Baffi J, Ambati J, Kompella UB, Ambati BK. Targeted intraceptor nanoparticle therapy reduces angiogenesis and fibrosis in primate and murine macular degeneration. ACS NANO 2013; 7:3264-75. [PMID: 23464925 PMCID: PMC3634882 DOI: 10.1021/nn305958y] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Monthly intraocular injections are widely used to deliver protein-based drugs that cannot cross the blood-retina barrier for the treatment of leading blinding diseases such as age-related macular degeneration (AMD). This invasive treatment carries significant risks, including bleeding, pain, infection, and retinal detachment. Further, current therapies are associated with a rate of retinal fibrosis and geographic atrophy significantly higher than that which occurs in the described natural history of AMD. A novel therapeutic strategy which improves outcomes in a less invasive manner, reduces risk, and provides long-term inhibition of angiogenesis and fibrosis is a felt medical need. Here we show that a single intravenous injection of targeted, biodegradable nanoparticles delivering a recombinant Flt23k intraceptor plasmid homes to neovascular lesions in the retina and regresses CNV in primate and murine AMD models. Moreover, this treatment suppressed subretinal fibrosis, which is currently not addressed by clinical therapies. Murine vision, as tested by OptoMotry, significantly improved with nearly 40% restoration of visual loss induced by CNV. We found no evidence of ocular or systemic toxicity from nanoparticle treatment. These findings offer a nanoparticle-based platform for targeted, vitreous-sparing, extended-release, nonviral gene therapy.
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Affiliation(s)
- Ling Luo
- Moran Eye Center, University of Utah, Salt Lake City,UT,USA, 84132
- Department of Ophthalmology, the 306th Hospital of PLA, Beijing, China, 10010
| | - Xiaohui Zhang
- Moran Eye Center, University of Utah, Salt Lake City,UT,USA, 84132
| | | | - Puneet Tyagi
- University of Colorado-Denver, Skaggs School of Pharmacy, Aurora, CO, USA, 80262
| | - Péter Barabás
- Moran Eye Center, University of Utah, Salt Lake City,UT,USA, 84132
| | - Hironori Uehara
- Moran Eye Center, University of Utah, Salt Lake City,UT,USA, 84132
| | - Tadashi R. Miya
- Moran Eye Center, University of Utah, Salt Lake City,UT,USA, 84132
| | - Nirbhai Singh
- Moran Eye Center, University of Utah, Salt Lake City,UT,USA, 84132
| | - Bonnie Archer
- Moran Eye Center, University of Utah, Salt Lake City,UT,USA, 84132
| | - Yureeda Qazi
- Moran Eye Center, University of Utah, Salt Lake City,UT,USA, 84132
| | - Kyle Jackman
- Moran Eye Center, University of Utah, Salt Lake City,UT,USA, 84132
| | - Subrata K. Das
- Moran Eye Center, University of Utah, Salt Lake City,UT,USA, 84132
| | - Thomas Olsen
- Moran Eye Center, University of Utah, Salt Lake City,UT,USA, 84132
| | | | - Brian C. Stagg
- Moran Eye Center, University of Utah, Salt Lake City,UT,USA, 84132
| | - Faisal Ahmed
- Moran Eye Center, University of Utah, Salt Lake City,UT,USA, 84132
| | - Lyska Emerson
- University of Utah, Dept. of Pathology, Salt Lake City, UT, USA, 84132
| | - Kristen Zygmunt
- University of Utah, Scientific Computing and Imaging Institute, Salt Lake City, UT, USA, 84132
| | - Ross Whitaker
- University of Utah, Scientific Computing and Imaging Institute, Salt Lake City, UT, USA, 84132
| | | | - Wei Huang
- Moran Eye Center, University of Utah, Salt Lake City,UT,USA, 84132
| | - Guangping Gao
- University of Massachusetts, Worcester, MA, USA, 01605
| | | | - David Krizaj
- Moran Eye Center, University of Utah, Salt Lake City,UT,USA, 84132
| | - Judit Baffi
- University of Kentucky, Lexington, KY, USA, 40536
| | | | - Uday B. Kompella
- University of Colorado-Denver, Skaggs School of Pharmacy, Aurora, CO, USA, 80262
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256
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Abstract
Diabetic retinopathy (DRP) is a common complication caused by multiple biochemical abnormalities of the underlying metabolic disease. While the incidence of DRP appears to decline due to evidence-based changes in diabetes management, the predicted increase in patients affected in particular by type 2 diabetes may outweigh the positive trend. The diagnosis is based on the alterations of the vessels, usually indicating abnormalities of the blood-retinal barrier and increased vasoregression, but the neuroglial elements appear equally vulnerable to the diabetic condition. Control of blood glucose, blood pressure and timely identification of coincident nephropathy are important to prevent progression to vision-threatening stages. Guidelines give specific indications for laser photocoagulation, in particular when euglycemia is no longer effective in preventing progression to advanced stages. Intravitreal administration of antibodies directed against the single best characterized propagator of clinically significant macular edema, vascular endothelial growth factor (VEGF), has become popular despite uncertainty about the patient subgroups which benefit best and the optimum administration schedule. Multifactorial intervention beyond glycemic control includes antihypertensive, lipid-lowering and antiaggregatory and is effective in type 2 diabetic patients with high-risk profiles, in particular coincident nephropathy.
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Affiliation(s)
- Hans-Peter Hammes
- 5th Medical Department, Universitätsmedizin Mannheim, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
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257
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Liu H, Zhang W, Xu Z, Caldwell RW, Caldwell RB, Brooks SE. Hyperoxia causes regression of vitreous neovascularization by downregulating VEGF/VEGFR2 pathway. Invest Ophthalmol Vis Sci 2013; 54:918-31. [PMID: 23307955 DOI: 10.1167/iovs.12-11291] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
PURPOSE Neovascularization (NV) is a sight-threatening complication of retinal ischemia in diabetes, retinal vein occlusion, and retinopathy of prematurity. Current treatment modalities, including laser photocoagulation and repeated intraocular injection of VEGF antagonists, are invasive and not always effective, and may carry side effects. We studied the use of hyperoxia as an alternative therapeutic strategy for regressing established vitreous NV in a mouse model of oxygen-induced ischemic retinopathy. METHODS Hyperoxia treatment (HT, 75% oxygen) was initiated on postnatal day (P)17 after the onset of vitreous NV. Immunohistochemistry and quantitative PCR were used to assess retinal vascular changes in relation to apoptosis, and expression of VEGFR2 and inflammatory molecules. Effects of intravitreal injections of VEGF-A, VEGF-E, PlGF-1, and VEGF trap were also studied. RESULTS HT selectively reduced NV by 70% within 24 hours. It robustly increased the level of cleaved caspase-3 in the vitreous NV between 6 and 18 hours and promoted infiltration of macrophage/microglial cells. The HT-induced apoptosis was preceded by a significant reduction in VEGFR2 expression within the NV and an increase in VEGFR2 within the surrounding neural tissue. Intravitreal VEGF-A and VEGF-E (VEGFR2 agonist) but not PlGF-1 (VEGFR1 agonist) prevented HT-induced apoptosis and regression of NV. In contrast, VEGF trap and VEGFR2 blockers mimicked the effect of HT. However, intravitreal VEGF trap induced increases in inflammatory molecules while HT did not have such unwanted effect. CONCLUSIONS HT may be clinically useful to specifically treat proliferative NV in ischemic retinopathy.
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Affiliation(s)
- Hua Liu
- Vascular Biology Center, Georgia Health Sciences University, Augusta, USA
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258
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Anand S. A brief primer on microRNAs and their roles in angiogenesis. Vasc Cell 2013; 5:2. [PMID: 23324117 PMCID: PMC3554556 DOI: 10.1186/2045-824x-5-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 01/11/2013] [Indexed: 01/08/2023] Open
Abstract
Development of the vasculature is a complex, dynamic process orchestrated by a balance of pro and anti-angiogenic signaling pathways. The same signaling pathways are mis-regulated and exploited during pathological angiogenesis in cancer, inflammation and cardiovascular diseases and contribute to disease progression. In the last decade, small non-coding RNA molecules termed microRNAs (miRs) have emerged as key regulators of several cellular processes including angiogenesis. It is becoming clear that miRs function in complex networks and regulate gene expression both at the mRNA and protein levels thereby altering cellular signaling responses to specific stimuli. In the vasculature, miRs can function either in a pro-angiogenic manner and potentiate angiogenesis or act as anti-angiogenic miRs by enhancing cell death and decreasing endothelial proliferation. This review aims to provide an update on how microRNAs regulate gene expression and illustrate miR function in the vasculature with a discussion of potential applications of miRs as anti-angiogenic therapeutics.
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Affiliation(s)
- Sudarshan Anand
- Moores UCSD Cancer Center, 3855 Health Sciences Drive #0803, La Jolla, CA, 92093, USA.
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