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Geiduschek EK, McDowell CM. The Fibro-Inflammatory Response in the Glaucomatous Optic Nerve Head. Int J Mol Sci 2023; 24:13240. [PMID: 37686046 PMCID: PMC10487997 DOI: 10.3390/ijms241713240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 08/24/2023] [Accepted: 08/25/2023] [Indexed: 09/10/2023] Open
Abstract
Glaucoma is a progressive disease and the leading cause of irreversible blindness. The limited therapeutics available are only able to manage the common risk factor of glaucoma, elevated intraocular pressure (IOP), indicating a great need for understanding the cellular mechanisms behind optic nerve head (ONH) damage during disease progression. Here we review the known inflammatory and fibrotic changes occurring in the ONH. In addition, we describe a novel mechanism of toll-like receptor 4 (TLR4) and transforming growth factor beta-2 (TGFβ2) signaling crosstalk in the cells of the ONH that contribute to glaucomatous damage. Understanding molecular signaling within and between the cells of the ONH can help identify new drug targets and therapeutics.
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Affiliation(s)
| | - Colleen M. McDowell
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI 53705, USA
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2
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Mavlyutov TA, Kuhn MS, Bilal SE, De Ieso ML, Chauhan AK, Stamer WD, McDowell CM. Decreased outflow facility and Schlemm's canal defects in a mouse model of glaucoma. Exp Eye Res 2022; 225:109249. [PMID: 36152913 PMCID: PMC9722577 DOI: 10.1016/j.exer.2022.109249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/24/2022] [Accepted: 09/12/2022] [Indexed: 12/29/2022]
Abstract
Previously we identified B6.EDA+/+ mice as a novel mouse model that presents with elevated IOP and trabecular meshwork damage. Here, we expand on our previous findings by measuring aqueous humor outflow facility and analyzing the integrity of the inner wall of Schlemm's canal. As expected, intraocular pressure (IOP) was increased, and outflow facility was decreased compared to C57BL/6J controls. B6.EDA+/+ mice had significantly increased expression of the adherens junction protein, VE-cadherin by the inner wall endothelium of Schlemm's canal. These data suggest that in addition to trabecular meshwork damage, there are changes in Schlemm's canal in B6.EDA+/+ mice that lead to aqueous outflow dysfunction and ocular hypertension.
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Affiliation(s)
- Timur A Mavlyutov
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, 53575, USA
| | - Megan S Kuhn
- Duke Eye Center, Duke University, Durham, NC, USA
| | - Samer E Bilal
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, 53575, USA
| | | | - Anil K Chauhan
- Department of Internal Medicine, Division of Hematology/Oncology, University of Iowa, Iowa City, IA, USA
| | | | - Colleen M McDowell
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, 53575, USA.
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3
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Mzyk P, Hernandez H, Le T, Ramirez JR, McDowell CM. Toll-Like Receptor 4 Signaling in the Trabecular Meshwork. Front Cell Dev Biol 2022; 10:936115. [PMID: 35912101 PMCID: PMC9335276 DOI: 10.3389/fcell.2022.936115] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 06/21/2022] [Indexed: 12/04/2022] Open
Abstract
Primary open-angle glaucoma is one of the leading causes of blindness worldwide. With limited therapeutics targeting the pathogenesis at the trabecular meshwork (TM), there is a great need for identifying potential new targets. Recent evidence has implicated Toll-like receptor 4 (TLR4) and it is signaling pathway in augmenting the effects of transforming growth factor beta-2 (TGFβ2) and downstream extracellular matrix production. In this review, we examine the role of TLR4 signaling in the trabecular meshwork and the interplay between endogenous activators of TLR4 (damage-associated molecular patterns (DAMPs)), extracellular matrix (ECM), and the effect on intraocular pressure
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Affiliation(s)
- Philip Mzyk
- University of Wisconsin-Madison, Madison, WI, United States
| | | | - Thanh Le
- University of Houston-Victoria, Victoria, TX, United States
| | | | - Colleen M. McDowell
- University of Wisconsin-Madison, Madison, WI, United States
- *Correspondence: Colleen M. McDowell,
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Mavlyutov TA, Myrah JJ, Chauhan AK, Liu Y, McDowell CM. Fibronectin extra domain A (FN-EDA) causes glaucomatous trabecular meshwork, retina, and optic nerve damage in mice. Cell Biosci 2022; 12:72. [PMID: 35619185 PMCID: PMC9137085 DOI: 10.1186/s13578-022-00800-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 04/27/2022] [Indexed: 12/15/2022] Open
Abstract
Background Elevated intraocular pressure (IOP) is a major risk factor for the development and progression of primary open angle glaucoma and is due to trabecular meshwork (TM) damage. Here, we investigate the role of an endogenous Toll-like receptor 4 (TLR4) ligand, FN-EDA, in the development of glaucoma utilizing a transgenic mouse strain (B6.EDA+/+) that constitutively expresses only FN containing the EDA isoform. Methods Eyes from C57BL6/J (wild-type), B6.EDA+/+ (constitutively active EDA), B6.EDA-/- (EDA null) mice were processed for electron microscopy and consecutive images of the entire length of the TM and Schlemm’s canal (SC) from anterior to posterior were collected and montaged into a single image. ECM accumulation, basement membrane length, and size and number of giant vacuoles were quantified by ImageJ analysis. Tlr4 and Iba1 expression in the TM and ONH cells was conducted using RNAscope in situ hybridization and immunohistochemistry protocols. IOP was measured using a rebound tonometer, ON damage assessed by PPD stain, and RGC loss quantified in RBPMS labeled retina flat mounts. Results Ultrastructure analyses show the TM of B6.EDA+/+ mice have significantly increased accumulation of ECM between TM beams with few empty spaces compared to C57BL/6 J mice (p < 0.05). SC basement membrane is thicker and more continuous in B6.EDA+/+ mice compared to C57BL/6 J. No significant structural differences are detected in the TM of EDA null mice. Tlr4 and Iba1 expression is increased in the TM of B6.EDA+/+ mice compared to C57BL/6 J eyes (p < 0.05). IOP is significantly higher in B6.EDA+/+ mice compared to C57BL/6 J eyes (p < 0.001), and significant ON damage (p < 0.001) and RGC loss (p < 0.05) detected at 1 year of age. Tlr4 mRNA is expressed in mouse ONH cells, and is present in ganglion cell axons, microglia, and astrocytes. There is a significant increase in the area occupied by Iba-1 positive microglia cells in the ONH of B6.EDA+/+ mice compared to C57BL/6 J control eyes (p < 0.01). Conclusions B6.EDA+/+ mice have increased ECM accumulation in the TM, elevated IOP, enhanced proinflammatory changes in the ONH, loss of RGCs, and ONH damage. These data suggest B6.EDA+/+ mice recapitulate many aspects of glaucomatous damage. Supplementary Information The online version contains supplementary material available at 10.1186/s13578-022-00800-y.
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Affiliation(s)
- Timur A Mavlyutov
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Justin J Myrah
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Anil K Chauhan
- Department of Internal Medicine, Division of Hematology/Oncology, University of Iowa, Iowa City, IA, USA
| | - Yang Liu
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Colleen M McDowell
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA.
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Mzyk P, Zalog EG, McDowell CM. A20 Attenuates the Fibrotic Response in the Trabecular Meshwork. Int J Mol Sci 2022; 23:ijms23041928. [PMID: 35216043 PMCID: PMC8875798 DOI: 10.3390/ijms23041928] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 02/04/2022] [Accepted: 02/07/2022] [Indexed: 02/05/2023] Open
Abstract
Although the extracellular matrix (ECM) in trabecular meshwork (TM) cells is known to be important in intraocular pressure (IOP) regulation, the molecular mechanisms involved in generating a glaucomatous environment in the TM are not completely understood. Recently we identified a molecular pathway, transforming growth factor beta 2 (TGFβ2)–toll-like receptor 4 (TLR4) signaling crosstalk, as an important regulator of glaucomatous damage in the TM, which contributes to fibrosis. Here we evaluate a novel molecular target, A20, also known as tumor necrosis factor alpha-induced protein 3 (TNFAIP3), which may help to block pathological TGFβ2–TLR4 signaling. Primary human TM cells were analyzed for A20 message and for A20 and fibronectin protein expression after treatment with TGFβ2. A20 message increased when the TLR4 pathway was inhibited in TM cells. In addition, TGFβ2, a known inducer of fibrosis, increased fibronectin expression, while at the same time decreasing the expression of A20. We then overexpressed A20 in TM cells in order to test the effect on treatment with TGFβ2, lipopolysaccharide (LPS), or cellular fibronectin extra domain A (cFN-EDA). Importantly, overexpression of A20 rescued the fibrotic response when TM cells were treated with TGFβ2, LPS, or cFN-EDA. In situ hybridization was used to probe for A20 RNA expression in age-matched control (C57BL/6J) mice and mice that constitutively express the EDA isoform of fibronectin (B6.EDA+/+). In this novel mouse model of glaucoma, A20 RNA was increased versus age-matched control mice in a cyclic manner at 6 weeks and 1 year of age, but not at 8 months. Overall, these data suggest that A20 may work through a negative feedback mechanism attenuating the ability of TGFβ2–TLR4 signaling to induce fibrosis.
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McDowell CM, Kizhatil K, Elliott MH, Overby DR, van Batenburg-Sherwood J, Millar JC, Kuehn MH, Zode G, Acott TS, Anderson MG, Bhattacharya SK, Bertrand JA, Borras T, Bovenkamp DE, Cheng L, Danias J, De Ieso ML, Du Y, Faralli JA, Fuchshofer R, Ganapathy PS, Gong H, Herberg S, Hernandez H, Humphries P, John SWM, Kaufman PL, Keller KE, Kelley MJ, Kelly RA, Krizaj D, Kumar A, Leonard BC, Lieberman RL, Liton P, Liu Y, Liu KC, Lopez NN, Mao W, Mavlyutov T, McDonnell F, McLellan GJ, Mzyk P, Nartey A, Pasquale LR, Patel GC, Pattabiraman PP, Peters DM, Raghunathan V, Rao PV, Rayana N, Raychaudhuri U, Reina-Torres E, Ren R, Rhee D, Chowdhury UR, Samples JR, Samples EG, Sharif N, Schuman JS, Sheffield VC, Stevenson CH, Soundararajan A, Subramanian P, Sugali CK, Sun Y, Toris CB, Torrejon KY, Vahabikashi A, Vranka JA, Wang T, Willoughby CE, Xin C, Yun H, Zhang HF, Fautsch MP, Tamm ER, Clark AF, Ethier CR, Stamer WD. Consensus Recommendation for Mouse Models of Ocular Hypertension to Study Aqueous Humor Outflow and Its Mechanisms. Invest Ophthalmol Vis Sci 2022; 63:12. [PMID: 35129590 PMCID: PMC8842499 DOI: 10.1167/iovs.63.2.12] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 12/08/2021] [Indexed: 01/07/2023] Open
Abstract
Due to their similarities in anatomy, physiology, and pharmacology to humans, mice are a valuable model system to study the generation and mechanisms modulating conventional outflow resistance and thus intraocular pressure. In addition, mouse models are critical for understanding the complex nature of conventional outflow homeostasis and dysfunction that results in ocular hypertension. In this review, we describe a set of minimum acceptable standards for developing, characterizing, and utilizing mouse models of open-angle ocular hypertension. We expect that this set of standard practices will increase scientific rigor when using mouse models and will better enable researchers to replicate and build upon previous findings.
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Affiliation(s)
- Colleen M. McDowell
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | | | - Michael H. Elliott
- University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Darryl R. Overby
- Department of Bioengineering, Imperial College London, United Kingdom
| | | | - J. Cameron Millar
- Department of Pharmacology & Neuroscience, and North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Markus H. Kuehn
- Department of Ophthalmology and Visual Sciences and Institute for Vision Research, The University of Iowa; Center for the Prevention and Treatment of Visual Loss, Veterans Affairs Medical Center, Iowa City, Iowa, United States
| | - Gulab Zode
- Department of Pharmacology & Neuroscience, and North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Ted S. Acott
- Ophthalmology and Biochemistry and Molecular Biology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Michael G. Anderson
- Department of Molecular Physiology and Biophysics and Department of Ophthalmology and Visual Sciences, The University of Iowa; Center for the Prevention and Treatment of Visual Loss, Veterans Affairs Medical Center, Iowa City, Iowa, United States
| | | | - Jacques A. Bertrand
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Terete Borras
- University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
| | | | - Lin Cheng
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
| | - John Danias
- SUNY Downstate Health Sciences University, Brooklyn, New York, United States
| | - Michael Lucio De Ieso
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, North Carolina, United States
| | - Yiqin Du
- Department of Ophthalmology, University of Pittsburgh, Pennsylvania, United States
| | - Jennifer A. Faralli
- Department of Pathology and Laboratory Medicine, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Rudolf Fuchshofer
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
| | - Preethi S. Ganapathy
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, New York, United States
| | - Haiyan Gong
- Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Samuel Herberg
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, New York, United States
| | | | - Peter Humphries
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Simon W. M. John
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - Paul L. Kaufman
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Kate E. Keller
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Mary J. Kelley
- Department of Ophthalmology and Department of Integrative Biosciences, Oregon Health & Science University, Portland, Oregon, United States
| | - Ruth A. Kelly
- Ocular Genetics Unit, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - David Krizaj
- Department of Ophthalmology, University of Utah School of Medicine, Salt Lake City, Utah, United States
| | - Ajay Kumar
- Department of Ophthalmology, University of Pittsburgh, Pennsylvania, United States
| | - Brian C. Leonard
- Department of Surgical and Radiological Sciences, University of California, Davis, Davis, California, United States
| | - Raquel L. Lieberman
- Department of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, United States
| | - Paloma Liton
- Department of Ophthalmology and Department of Pathology, Duke University, Durham, North Carolina, United States
| | - Yutao Liu
- Department of Cellular Biology and Anatomy, James & Jean Culver Vision Discovery Institute, Augusta University, Augusta, Georgia, United States
| | - Katy C. Liu
- Duke Eye Center, Duke Health, Durham, North Carolina, United States
| | - Navita N. Lopez
- Department of Neurobiology, University of Utah, Salt Lake City, Utah, United States
| | - Weiming Mao
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Timur Mavlyutov
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Fiona McDonnell
- Duke Eye Center, Duke Health, Durham, North Carolina, United States
| | - Gillian J. McLellan
- Department of Surgical Sciences and Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Philip Mzyk
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Andrews Nartey
- College of Optometry, University of Houston, Houston, Texas, United States
| | - Louis R. Pasquale
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, New York, United States
| | - Gaurang C. Patel
- Ophthalmology Research, Regeneron Pharmaceuticals, Tarreytown, New York, United States
| | | | - Donna M. Peters
- Department of Pathology and Laboratory Medicine, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | | | - Ponugoti Vasantha Rao
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States
| | - Naga Rayana
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Urmimala Raychaudhuri
- Department of Neurobiology, University of California, Irvine, Irvine, California, United States
| | - Ester Reina-Torres
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Ruiyi Ren
- Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Douglas Rhee
- Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Uttio Roy Chowdhury
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - John R. Samples
- Washington State University, Floyd Elson College of Medicine, Spokane, Washington, United States
| | | | - Najam Sharif
- Santen Inc., Emeryville, California, United States
| | - Joel S. Schuman
- Department of Ophthalmology and Department of Physiology and Neuroscience, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, United States; Departments of Biomedical Engineering and Electrical and Computer Engineering, New York University Tandon School of Engineering, Brooklyn, New York, United States; Center for Neural Science, College of Arts and Science, New York University, New York, New York, United States
| | - Val C. Sheffield
- Department of Pediatrics and Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States
| | - Cooper H. Stevenson
- Department of Pharmacology & Neuroscience, and North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Avinash Soundararajan
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | | | - Chenna Kesavulu Sugali
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Yang Sun
- Veterans Affairs Palo Alto Health Care System, Stanford University, Palo Alto, California, United States
| | - Carol B. Toris
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States; Department of Ophthalmology and Vision Sciences, The Ohio State University, Columbus, Ohio, United States
| | | | - Amir Vahabikashi
- Cell and Developmental Biology Department, Northwestern University, Chicago, Illinois, United States
| | - Janice A. Vranka
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Ting Wang
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Colin E. Willoughby
- Genomic Medicine, Biomedical Sciences Research Institute, Ulster University, Coleraine, Northern Ireland, United Kingdom
| | - Chen Xin
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Hongmin Yun
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Hao F. Zhang
- Biomedical Engineering Department, Northwestern University, Evanston, Illinois, United States
| | - Michael P. Fautsch
- Biomedical Engineering Department, Northwestern University, Evanston, Illinois, United States
| | | | - Abbot F. Clark
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - C. Ross Ethier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology; Emory University School of Medicine, Emory University, Atlanta, Georgia, United States
| | - W. Daniel Stamer
- Duke Ophthalmology, Duke University, Durham, North Carolina, United States
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7
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Geiduschek EK, Milne PD, Mzyk P, Mavlyutov TA, McDowell CM. TLR4 signaling modulates extracellular matrix production in the lamina cribrosa. Front Ophthalmol (Lausanne) 2022; 2:968381. [PMID: 36911656 PMCID: PMC9997209 DOI: 10.3389/fopht.2022.968381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The optic nerve head (ONH) is a place of vulnerability during glaucoma progression due to increased intraocular pressure damaging the retinal ganglion cell axons. The molecular signaling pathways involved in generating glaucomatous ONH damage has not been fully elucidated. There is a great deal of evidence that pro-fibrotic TGFβ2 signaling is involved in modulating the ECM environment within the lamina cribrosa (LC) region of the ONH. Here we investigated the role of signaling crosstalk between the TGFβ2 pathway and the toll-like receptor 4 (TLR4) pathway within the LC. ECM deposition was examined between healthy and glaucomatous human ONH sections, finding increases in fibronectin and fibronectin extra domain A (FN-EDA) an isoform of fibronectin known to be a damage associated molecular pattern (DAMP) that can activate TLR4 signaling. In human LC cell cultures derived from healthy donor eyes, inhibition of TLR4 signaling blocked TGFβ2 induced FN and FN-EDA expression. Activation of TLR4 by cellular FN (cFN) containing the EDA isoform increased both total FN production and Collagen-1 production and this effect was dependent on TLR4 signaling. These studies identify TGFβ2-TLR4 signaling crosstalk in LC cells of the ONH as a novel pathway regulating ECM and DAMP production.
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Affiliation(s)
- Emma K Geiduschek
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Paige D Milne
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Philip Mzyk
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Timur A Mavlyutov
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Colleen M McDowell
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, United States
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8
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Sorenson CM, Song YS, Zaitoun IS, Wang S, Hanna BA, Darjatmoko SR, Gurel Z, Fisk DL, McDowell CM, McAdams RM, Sheibani N. Caffeine Inhibits Choroidal Neovascularization Through Mitigation of Inflammatory and Angiogenesis Activities. Front Cell Dev Biol 2021; 9:737426. [PMID: 34722519 PMCID: PMC8551619 DOI: 10.3389/fcell.2021.737426] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 09/13/2021] [Indexed: 12/20/2022] Open
Abstract
Adenosine receptors (AR) are widely expressed in a variety of tissues including the retina and brain. They are involved in adenosine-mediated immune responses underlying the onset and progression of neurodegenerative diseases. The expression of AR has been previously demonstrated in some retinal cells including endothelial cells and retinal pigment epithelial cells, but their expression in the choroid and choroidal cells remains unknown. Caffeine is a widely consumed AR antagonist that can influence inflammation and vascular cell function. It has established roles in the treatment of neonatal sleep apnea, acute migraine, and post lumbar puncture headache as well as the neurodegenerative diseases such as Parkinson and Alzheimer. More recently, AR antagonism with caffeine has been shown to protect preterm infants from ischemic retinopathy and retinal neovascularization. However, whether caffeine impacts the development and progression of ocular age-related diseases including neovascular age-related macular degermation remains unknown. Here, we examined the expression of AR in retinal and choroidal tissues and cells. We showed that antagonism of AR with caffeine or istradefylline decreased sprouting of thoracic aorta and choroid/retinal pigment epithelium explants in ex vivo cultures, consistent with caffeine's ability to inhibit endothelial cell migration in culture. In vivo studies also demonstrated the efficacy of caffeine in inhibition of choroidal neovascularization and mononuclear phagocyte recruitment to the laser lesion sites. Istradefylline, a specific AR 2A antagonist, also decreased choroidal neovascularization. Collectively, our studies demonstrate an important role for expression of AR in the choroid whose antagonism mitigate choroidal inflammatory and angiogenesis activities.
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Affiliation(s)
- Christine M Sorenson
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States.,McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Yong-Seok Song
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Ismail S Zaitoun
- McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States.,Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Shoujian Wang
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Barbara A Hanna
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Soesiawati R Darjatmoko
- McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States.,Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Zafer Gurel
- Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Debra L Fisk
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Colleen M McDowell
- McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States.,Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Ryan M McAdams
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Nader Sheibani
- McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States.,Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States.,Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States.,Department of Biomedical Engineering, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
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Faralli JA, Filla MS, McDowell CM, Peters DM. Disruption of fibronectin fibrillogenesis affects intraocular pressure (IOP) in BALB/cJ mice. PLoS One 2020; 15:e0237932. [PMID: 32822410 PMCID: PMC7444551 DOI: 10.1371/journal.pone.0237932] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 08/05/2020] [Indexed: 12/31/2022] Open
Abstract
Increased deposition of fibronectin fibrils containing EDA+fibronectin by TGFβ2 is thought to be involved in the reduction of aqueous humor outflow across the trabecular meshwork (TM) of the eye and the elevation in intraocular pressure (IOP) observed in primary open angle glaucoma (POAG). Using a fibronectin-binding peptide called FUD that can disrupt fibronectin fibrillogenesis, we examined if disrupting fibronectin fibrillogenesis would affect IOP in the TGFβ2 BALB/cJ mouse model of ocular hypertension. BALB/cJ mice that had been intravitreally injected with an adenovirus (Ad5) expressing a bioactive TGFβ2226/228 showed a significant increase in IOP after 2 weeks. When 1μM FUD was injected intracamerally into mice 2 weeks post Ad5-TGFβ2 injection, FUD significantly reduced IOP after 2 days. Neither mutated FUD (mFUD) nor PBS had any effect on IOP. Four days after FUD was injected, IOP returned to pre-FUD injection levels. In the absence of TGFβ2, intracameral injection of FUD had no effect on IOP. Western blotting of mouse anterior segments expressing TGFβ2 showed that FUD decreased fibronectin levels 2 days after intracameral injection (p<0.05) but not 7 days compared to eyes injected with PBS. mFUD injection had no significant effect on fibronectin levels at any time point. Immunofluorescence microscopy studies in human TM (HTM) cells showed that treatment with 2ng/ml TGFβ2 increased the amount of EDA+ and EDB+ fibronectin incorporated into fibrils and 2μM FUD decreased both EDA+ and EDB+ fibronectin in fibrils. An on-cell western assay validated this and showed that FUD caused a 67% reduction in deoxycholate insoluble fibronectin fibrils in the presence of TGFβ2. FUD also caused a 43% reduction in fibronectin fibrillogenesis in the absence of TGFβ2 while mFUD had no effect. These studies suggest that targeting the assembly of fibronectin fibrillogenesis may represent a way to control IOP.
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Affiliation(s)
- Jennifer A. Faralli
- Department of Pathology and Laboratory Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Mark S. Filla
- Department of Pathology and Laboratory Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Colleen M. McDowell
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Donna M. Peters
- Department of Pathology and Laboratory Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, United States of America
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, United States of America
- * E-mail:
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Hernandez H, Roberts AL, McDowell CM. Nuclear factor-kappa beta signaling is required for transforming growth factor Beta-2 induced ocular hypertension. Exp Eye Res 2020; 191:107920. [PMID: 31923415 DOI: 10.1016/j.exer.2020.107920] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 12/18/2019] [Accepted: 01/05/2020] [Indexed: 01/22/2023]
Abstract
A major risk for the development of primary open-angle glaucoma (POAG) is elevated intraocular pressure (IOP). Elevated IOP is caused by increased outflow resistance due in part to excessive extracellular matrix (ECM) deposition in the trabecular meshwork (TM). The role of transforming growth factor beta 2 (TGFβ2) in inducing ECM production is well understood. Recent studies suggest that toll-like receptor 4 (TLR4) plays an important role in fibrogenesis. We have previously described a crosstalk between TGFβ2 and TLR4 in the development of ocular hypertension and glaucomatous TM damage. Nuclear factor-kappa beta (NF-κB) is critical for TLR4 signaling. To determine the transactivation of NF-κB, TM cells were stimulated with cellular fibronectin containing the EDA isoform (cFN-EDA), TGFβ2, or lipopolysaccharide (LPS) in combination with a selective TLR4 inhibitor. cFN-EDA, TGFβ2, and LPS all induced transactivation of NF-κB and inhibition of TLR4 blocked the effect of each treatment paradigm. To evaluate the role of NF-κB in IOP regulation, we utilized our inducible mouse model of ocular hypertension by injection of Ad5.TGFβ2 in mice harboring a mutation in NF-κB and wild-type controls. IOP was measured over time and eyes accessed by immunohistochemistry for the ECM protein FN and the specific FN-EDA isoform. Ad5.TGFβ2 induced ocular hypertension and expression of FN and FN-EDA in wild-type mice, but mutation in NF-κB blocked the effect. These data suggest that NF-κB is necessary for TGFβ2-induced ECM production and ocular hypertension and the transactivation of NF-κB is dependent on both TGFβ2 and TLR4.
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Affiliation(s)
- Humberto Hernandez
- North Texas Eye Research Institute, Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, 76107, USA
| | - Amanda L Roberts
- North Texas Eye Research Institute, Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, 76107, USA
| | - Colleen M McDowell
- University of Wisconsin-Madison, Department of Ophthalmology and Visual Sciences, Madison, WI, 53706, USA.
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Sharma TP, Curry S, McDowell CM. Effects of Toll-Like Receptor 4 Inhibition on Transforming Growth Factor-β2 Signaling in the Human Trabecular Meshwork. J Ocul Pharmacol Ther 2019; 36:170-178. [PMID: 31834824 DOI: 10.1089/jop.2019.0076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Purpose: Transforming growth factor-β2 (TGFβ2) and Toll-like receptor 4 (TLR4) crosstalk have been implicated in extracellular matrix regulation in the trabecular meshwork (TM) and ocular hypertension in mice. We investigated TLR4 expression in normal and glaucomatous human trabecular meshwork (HTM) sections and utilized a human perfusion organ culture model to determine TGFβ2-TLR4 signaling crosstalk in glaucoma. Methods: Expression of TLR4 was determined in TM of normal and glaucomatous human eyes. Anterior segments of paired human eyes were perfused at a constant flow rate (2.5 μL/min) for 4 days to acquire stable baseline intraocular pressures (IOPs). We treated paired eyes with two different treatment paradigms: (1) TGFβ2 in one eye and vehicle control in the paired eye, (2) TGFβ2 in one eye and TGFβ2 + TLR4 inhibitor TAK-242 in the paired eye. Perfusate and TM tissue were collected and analyzed for fibronectin (FN) and collagen IV (COLIV) expression. Results: We observed increased TLR4 expression in glaucomatous HTM sections compared to normal (age-matched) (P < 0.05). Significant elevation of IOP was detected in 47% of TGFβ2-treated anterior segments (P < 0.01) compared to control, and in TGFβ2 treated compared with co-treatment with TGFβ2 + TLR4 inhibitor (P < 0.0001). An increase in FN and COLIV expression was observed after TGFβ2 treatment, and inhibition of TLR4 signaling decreased TGFβ2-induced FN and COLIV expression in perfusate (P < 0.05). Conclusions: These studies identify TGFβ2-TLR4 crosstalk as a novel pathway in glaucoma. They provide a potential new target to lower IOP and explore glaucoma pathogenesis.
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Affiliation(s)
- Tasneem P Sharma
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas
| | - Stacy Curry
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas
| | - Colleen M McDowell
- Department of Ophthalmology and Visual Sciences, McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, Wisconsin
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Hernandez H, Millar JC, Curry SM, Clark AF, McDowell CM. BMP and Activin Membrane Bound Inhibitor Regulates the Extracellular Matrix in the Trabecular Meshwork. Invest Ophthalmol Vis Sci 2018; 59:2154-2166. [PMID: 29801150 PMCID: PMC5915111 DOI: 10.1167/iovs.17-23282] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 03/22/2018] [Indexed: 01/18/2023] Open
Abstract
Purpose The trabecular meshwork (TM) has an important role in the regulation of aqueous humor outflow and IOP. Regulation of the extracellular matrix (ECM) by TGFβ2 has been studied extensively. Bone morphogenetic protein (BMP) and activin membrane-bound inhibitor (BAMBI) has been shown to inhibit or modulate TGFβ2 signaling. We investigate the role of TGFβ2 and BAMBI in the regulation of TM ECM and ocular hypertension. Methods Mouse TM (MTM) cells were isolated from B6;129S1-Bambitm1Jian/J flox mice, characterized for TGFβ2 and dexamethasone (DEX)-induced expression of fibronectin, collagen-1, collagen-4, laminin, α-smooth muscle actin, cross-linked actin networks (CLANs) formation, and DEX-induced myocilin (MYOC) expression. MTM cells were transduced with Ad5.GFP to identify transduction efficiency. MTM cells and mouse eyes were transduced with Ad5.Null, Ad5.Cre, Ad5.TGFβ2, or Ad5.TGFβ2 + Ad5.Cre to evaluate the effect on ECM production, IOP, and outflow facility. Results MTM cells express TM markers and respond to DEX and TGFβ2. Ad5.GFP at 100 MOI had the highest transduction efficiency. Bambi knockdown by Ad5.Cre and Ad5.TGFβ2 increased fibronectin, collagen-1, and collagen-4 in TM cells in culture and tissue. Ad5.Cre, Ad5.TGFβ2, and Ad5.TGFβ2 + Ad5.Cre each significantly induced ocular hypertension and lowered aqueous humor outflow facility in transduced eyes. Conclusions We show for the first time to our knowledge that knockdown of Bambi alters ECM expression in cultured cells and mouse TM, reduces outflow facility, and causes ocular hypertension. These data provide a novel insight into the development of glaucomatous TM damage and identify BAMBI as an important regulator of TM ECM and ocular hypertension.
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Affiliation(s)
- Humberto Hernandez
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - J. Cameron Millar
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Stacy M. Curry
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Abbot F. Clark
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Colleen M. McDowell
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
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Keller KE, Bhattacharya SK, Borrás T, Brunner TM, Chansangpetch S, Clark AF, Dismuke WM, Du Y, Elliott MH, Ethier CR, Faralli JA, Freddo TF, Fuchshofer R, Giovingo M, Gong H, Gonzalez P, Huang A, Johnstone MA, Kaufman PL, Kelley MJ, Knepper PA, Kopczynski CC, Kuchtey JG, Kuchtey RW, Kuehn MH, Lieberman RL, Lin SC, Liton P, Liu Y, Lütjen-Drecoll E, Mao W, Masis-Solano M, McDonnell F, McDowell CM, Overby DR, Pattabiraman PP, Raghunathan VK, Rao PV, Rhee DJ, Chowdhury UR, Russell P, Samples JR, Schwartz D, Stubbs EB, Tamm ER, Tan JC, Toris CB, Torrejon KY, Vranka JA, Wirtz MK, Yorio T, Zhang J, Zode GS, Fautsch MP, Peters DM, Acott TS, Stamer WD. Consensus recommendations for trabecular meshwork cell isolation, characterization and culture. Exp Eye Res 2018; 171:164-173. [PMID: 29526795 PMCID: PMC6042513 DOI: 10.1016/j.exer.2018.03.001] [Citation(s) in RCA: 197] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 03/01/2018] [Indexed: 12/30/2022]
Abstract
Cultured trabecular meshwork (TM) cells are a valuable model system to study the cellular mechanisms involved in the regulation of conventional outflow resistance and thus intraocular pressure; and their dysfunction resulting in ocular hypertension. In this review, we describe the standard procedures used for the isolation of TM cells from several animal species including humans, and the methods used to validate their identity. Having a set of standard practices for TM cells will increase the scientific rigor when used as a model, and enable other researchers to replicate and build upon previous findings.
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Affiliation(s)
| | | | | | | | | | - Abbott F Clark
- University of North Texas Health Sciences Center, United States
| | | | - Yiqin Du
- University of Pittsburgh, United States
| | | | | | | | - Thomas F Freddo
- Massachusetts College of Pharmacy and Health Sciences, United States
| | | | | | | | | | - Alex Huang
- University of California, Los Angeles, United States
| | | | | | | | | | | | | | | | | | | | - Shan C Lin
- University of California, San Francisco, United States
| | | | | | | | - Weiming Mao
- University of North Texas Health Sciences Center, United States
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - James C Tan
- University of Southern California, United States
| | | | | | | | - Mary K Wirtz
- Oregon Health and Science University, United States
| | - Thomas Yorio
- University of North Texas Health Sciences Center, United States
| | - Jie Zhang
- University of California, Los Angeles, United States
| | - Gulab S Zode
- University of North Texas Health Sciences Center, United States
| | - Michael P Fautsch
- Department of Ophthalmology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905, United States.
| | - Donna M Peters
- Department of Pathology & Laboratory Medicine, University of Wisconsin, 1300 University Ave, Madison, WI 53706, United States.
| | - Ted S Acott
- Department of Ophthalmology, Department of Biochemistry & Molecular Biology, Oregon Health and Science University, 3181 SW Sam Jackson Park Rd, Portland, OR 97239, United States.
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, DUMC 3802, Durham, NC 27705, United States.
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Hernandez H, Medina-Ortiz WE, Luan T, Clark AF, McDowell CM. Crosstalk Between Transforming Growth Factor Beta-2 and Toll-Like Receptor 4 in the Trabecular Meshwork. Invest Ophthalmol Vis Sci 2017; 58:1811-1823. [PMID: 28346614 PMCID: PMC5374883 DOI: 10.1167/iovs.16-21331] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Purpose The trabecular meshwork (TM) is involved in the outflow of aqueous humor and intraocular pressure (IOP) regulation. Regulation of the extracellular matrix (ECM) by TGFβ2 signaling pathways in the TM has been extensively studied. Recent evidence has implicated toll-like receptor 4 (TLR4) in the regulation of ECM and fibrogenesis in liver, kidney, lung, and skin. Here, we investigated the role of TGFβ2-TLR4 signaling crosstalk in the regulation of the ECM in the TM and ocular hypertension. Methods Cross sections of human donor eyes, primary human TM cells in culture, and dissected mouse TM rings were used to determine Tlr4 expression in the TM. Trabecular meshwork cells in culture were treated with TGFβ2 (5 ng/mL), TLR4 inhibitor (TAK-242, 15 μM), and a TLR4 ligand (cellular fibronectin isoform [cFN]-EDA). A/J (n = 13), AKR/J (n = 7), BALBc/J (n = 8), C3H/HeJ (n = 20), and C3H/HeOuJ (n = 10) mice were injected intravitreally with adenovirus 5 (Ad5).hTGFβ2c226s/c228s in one eye, with the uninjected contralateral eye serving as a control. Conscious IOP measurements were taken using a TonoLab rebound tonometer. Results Toll-like receptor 4 is expressed in the human and mouse TM. Inhibition of TLR4 signaling in the presence of TGFβ2 decreases fibronectin expression. Activation of TLR4 by cFN-EDA in the presence of TGFβ2 further increases fibronectin, laminin, and collagen-1 expression, and TLR4 signaling inhibition blocks this effect. Ad5.hTGFβ2c226s/c228s induces ocular hypertension in wild-type mice but has no effect in Tlr4 mutant (C3H/HeJ) mice. Conclusions These studies identify TGFβ2-TLR4 crosstalk as a novel pathway involved in ECM regulation in the TM and ocular hypertension. These data further explain the complex mechanisms involved in the development of glaucomatous TM damage.
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Affiliation(s)
- Humberto Hernandez
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Wanda E Medina-Ortiz
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Tomi Luan
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Abbot F Clark
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Colleen M McDowell
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
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McDowell CM, Hernandez H, Mao W, Clark AF. Gremlin Induces Ocular Hypertension in Mice Through Smad3-Dependent Signaling. Invest Ophthalmol Vis Sci 2015; 56:5485-92. [PMID: 26284554 DOI: 10.1167/iovs.15-16993] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PURPOSE Transforming growth factor-β2 induces extracellular matrix (ECM) remodeling, which likely contributes to the defective function of the trabecular meshwork (TM) leading to glaucomatous ocular hypertension. Bone morphogenetic proteins (BMPs) inhibit these profibrotic effects of TGFβ2. The BMP antagonist gremlin is elevated in glaucomatous TM cells and increases IOP in an ex vivo perfusion culture model. The purpose of this study was to determine whether gremlin regulates ECM proteins in the TM, signals through the Smad3-dependent pathway, and induces ocular hypertension in mice. METHODS Ad5.Gremlin or Ad5.TGFβ2 was injected intravitreally into one eye of each mouse. Intraocular pressure measurements were taken using a TonoLab tonometer. Gremlin, TGFβ2, fibronectin (FN), and collagen-1 (Col-1) expression in the TM was determined by immunofluorescence, Western immunoblot, and quantitative (q)PCR analyses. RESULTS Ad5.Gremlin or Ad5.TGFβ2 each caused significant IOP elevation in mice. Immunofluorescence and Western blot analysis demonstrated that gremlin and TGFβ2 reciprocally increased the expression of each other, and both increased FN expression in the TM and surrounding tissues. Ad5.Gremlin elevated IOP and increased Fn and Col-1 gene expression in the TM of Smad3 wild-type (WT) mice, but had no effect in Smad3 HET or Smad3 KO mice. CONCLUSIONS Our results demonstrate that intravitreal injections of either Ad5.Gremlin or Ad5.TGFβ2 elevate IOP and upregulate the ECM protein FN in the TM of mice. These data show that gremlin signals through the Smad3-dependent pathway in the TM to elevate IOP. We determined for the first time gremlin's role in inducing ocular hypertension in an in vivo model system.
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Liu Y, McDowell CM, Zhang Z, Tebow HE, Wordinger RJ, Clark AF. Monitoring retinal morphologic and functional changes in mice following optic nerve crush. Invest Ophthalmol Vis Sci 2014; 55:3766-74. [PMID: 24854856 DOI: 10.1167/iovs.14-13895] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We characterized the morphologic and functional changes in optic nerve crushed mice and evaluated electroretinogram (ERG) responses as tools to monitor retinal ganglion cell (RGC) dysfunction. METHODS We performed optic nerve crush (ONC) unilaterally in adult BALB/cJ mice. The neuronal loss in the RGC layer (GCL) and superior colliculus (SC) was determined by Nissl staining. Retinal thickness was assessed by spectral-domain optical coherence tomography (SD-OCT) imaging. Retinal function was determined by pattern ERG and full-field flash ERG. Responses of pattern ERG, positive scotopic threshold response (pSTR), scotopic oscillatory potentials (OPs), and photopic negative response (PhNR) were analyzed. RESULTS The ONC induced progressive neuronal loss in GCL and contralateral SC starting from 7 and 28 days following ONC, respectively. A linear correlation was observed between combined thickness of nerve fiber layer (NFL), GCL, and inner plexiform layer (IPL) imaged by SD-OCT and cell numbers in GCL. Only half of the normal BALB/cJ mice exhibited pattern ERG response, which was smaller and later compared to C57BL/6J mice. The ONC reduced pattern ERG and pSTR, but the reduction of pattern ERG was earlier than pSTR, preceding the anatomical cell loss in the GCL. The PhNR and scotopic OPs were not affected by ONC. CONCLUSIONS The SD-OCT and ERG can be used to monitor noninvasively retinal morphologic and functional changes induced by ONC. Pattern ERG and pSTR are able to detect early RGC dysfunction, but pattern ERG exhibits higher sensitivity. Our results support the use of these tools in studies using the mouse ONC model.
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Affiliation(s)
- Yang Liu
- North Texas Eye Research Institute and Department of Cell Biology and Immunology, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Colleen M McDowell
- North Texas Eye Research Institute and Department of Cell Biology and Immunology, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Zhang Zhang
- North Texas Eye Research Institute and Department of Cell Biology and Immunology, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Holly E Tebow
- North Texas Eye Research Institute and Department of Cell Biology and Immunology, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Robert J Wordinger
- North Texas Eye Research Institute and Department of Cell Biology and Immunology, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Abbot F Clark
- North Texas Eye Research Institute and Department of Cell Biology and Immunology, University of North Texas Health Science Center, Fort Worth, Texas, United States
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Sharma TP, McDowell CM, Liu Y, Wagner AH, Thole D, Faga BP, Wordinger RJ, Braun TA, Clark AF. Optic nerve crush induces spatial and temporal gene expression patterns in retina and optic nerve of BALB/cJ mice. Mol Neurodegener 2014; 9:14. [PMID: 24767545 PMCID: PMC4113182 DOI: 10.1186/1750-1326-9-14] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 04/18/2014] [Indexed: 12/18/2022] Open
Abstract
Background Central nervous system (CNS) trauma and neurodegenerative disorders trigger a cascade of cellular and molecular events resulting in neuronal apoptosis and regenerative failure. The pathogenic mechanisms and gene expression changes associated with these detrimental events can be effectively studied using a rodent optic nerve crush (ONC) model. The purpose of this study was to use a mouse ONC model to: (a) evaluate changes in retina and optic nerve (ON) gene expression, (b) identify neurodegenerative pathogenic pathways and (c) discover potential new therapeutic targets. Results Only 54% of total neurons survived in the ganglion cell layer (GCL) 28 days post crush. Using Bayesian Estimation of Temporal Regulation (BETR) gene expression analysis, we identified significantly altered expression of 1,723 and 2,110 genes in the retina and ON, respectively. Meta-analysis of altered gene expression (≥1.5, ≤-1.5, p < 0.05) using Partek and DAVID demonstrated 28 up and 20 down-regulated retinal gene clusters and 57 up and 41 down-regulated optic nerve clusters. Regulated gene clusters included regenerative change, synaptic plasticity, axonogenesis, neuron projection, and neuron differentiation. Expression of selected genes (Vsnl1, Syt1, Synpr and Nrn1) from retinal and ON neuronal clusters were quantitatively and qualitatively examined for their relation to axonal neurodegeneration by immunohistochemistry and qRT-PCR. Conclusion A number of detrimental gene expression changes occur that contribute to trauma-induced neurodegeneration after injury to ON axons. Nrn1 (synaptic plasticity gene), Synpr and Syt1 (synaptic vesicle fusion genes), and Vsnl1 (neuron differentiation associated gene) were a few of the potentially unique genes identified that were down-regulated spatially and temporally in our rodent ONC model. Bioinformatic meta-analysis identified significant tissue-specific and time-dependent gene clusters associated with regenerative changes, synaptic plasticity, axonogenesis, neuron projection, and neuron differentiation. These ONC induced neuronal loss and regenerative failure associated clusters can be extrapolated to changes occurring in other forms of CNS trauma or in clinical neurodegenerative pathological settings. In conclusion, this study identified potential therapeutic targets to address two key mechanisms of CNS trauma and neurodegeneration: neuronal loss and regenerative failure.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Abbot F Clark
- North Texas Eye Research Institute, Ft, Worth, TX USA.
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McDowell CM, Tebow HE, Wordinger RJ, Clark AF. Smad3 is necessary for transforming growth factor-beta2 induced ocular hypertension in mice. Exp Eye Res 2013; 116:419-23. [PMID: 24184030 DOI: 10.1016/j.exer.2013.10.017] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 10/21/2013] [Accepted: 10/23/2013] [Indexed: 11/19/2022]
Abstract
TGFβ2 induces extracellular matrix (ECM) remodeling and alters the cytoskeleton by both the canonical Smad and non-canonical signaling pathways. TGFβ2 regulates the expression of ECM proteins in trabecular meshwork (TM) cells, increases intraocular pressure (IOP) in an ex vivo perfusion organ culture model, and induces ocular hypertension in rodent eyes. A necessary step in the canonical Smad signaling pathway is phosphorylation of receptor protein Smad3 by the TGF-β receptor complex. The purpose of this study was to determine whether TGFβ2 signals in vivo through the canonical Smad signaling pathway in the TM using Smad3 knockout (KO) mice. Ad5.hTGFβ2(226/228) (2.5 × 10(7) pfu) was injected intravitreally into one eye of homozygous (WT), heterozygous (HET), and homozygous (KO) 129-Smad3(tm1Par)/J mice (n = 9-10 mice/group), with the uninjected contralateral eye serving as the control. IOP measurements were taken using a rebound tonometer. To test the effect of TGFβ2 signaling on the ECM, fibronectin expression was determined by immunohistochemistry and qPCR analysis. Transduction of the TM with viral vector Ad5.hTGFβ2(226/228) caused a statistically significant difference in IOP exposure between Smad3 genotypes: WT, 187.7 ± 23.9 mmHg*day (n = 9); HET, 95.6 ± 24.5 mmHg*day (n = 9); KO, 52.8 ± 25.2 mmHg*day (n = 10); (p < 0.05 WT versus HET, p < 0.01 WT versus KO). Immunohistochemistry and qPCR analysis showed that Ad5.hTGFβ2(226/228) increased fibronectin expression in the TM of WT mice (2.23 ± 0.24 fold) compared to Smad3 KO mice (0.99 ± 0.19 fold), p < 0.05. These results demonstrate Smad3 is a necessary signaling protein for TGFβ2-induced ocular hypertension and fibronectin deposition in the TM.
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Affiliation(s)
- Colleen M McDowell
- North Texas Eye Research Institute, Department of Cell Biology and Anatomy, University of North Texas Health Science Center, CBH-441, 3500 Camp Bowie Blvd, Fort Worth, TX 76107, USA
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Abstract
In many designs of total knee arthroplasty, the patella with one central peg has been replaced by a patella with three small pegs for cement fixation. There have been recent reports of failure of this design. This is a prospective, consecutive study of two types of patella component fixation in 228 posterior-stabilized knee arthroplasties done by one surgeon. A central peg all-polyethylene component was used for 84 consecutive knees in 63 patients (Group A) and a three-peg patella was used for the next 144 consecutive knees in 99 patients (Group B). The mean followup was 6.7 years (range, 2-10 years) for Group A and 3.5 years (range, 2-6 years) for Group B. Except for the patellar component fixation, all knees had the same posterior-stabilized prosthesis using a specific protocol for patellar resurfacing. No patient required reoperation for a patellofemoral complication. The prevalence of patella fracture was higher in Group A, 4.7% (four knees), compared with 2.1% (three knees) in Group B, but this difference was not statistically significant. The presence of anterior knee pain referable to the patella was 7.1% (five patients, six knees) in Group A (one patient with two knees had severe anterior knee pain) and 9% (13 knees in 13 patients) in Group B. There was no patella clunk syndrome, subluxation, or fracture of a fixation peg in either group. With this specific protocol for patella resurfacing, there was a higher rate of complications with the one central peg patella (4.7%) than with the three-peg patella (2.1%), but this did not reach statistical significance. The results do not support an increased risk of component failure with this three-peg patella design, but do not, at this length of followup, show any significant advantage of three-peg fixation.
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Affiliation(s)
- C M Larson
- University of North Carolina-Chapel Hill, Department of Orthopaedics, 27599, USA
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20
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Abstract
BACKGROUND Younger patients are having total hip arthroplasty now, and a woman who has had such a procedure may want to become pregnant. The purposes of this study were to report on a series of women who had completed a pregnancy after a total hip arthroplasty and to determine if pregnancy affects the function and longevity of the prosthesis. METHODS Five women, with a total of seven uncemented total hip replacements, had six successful pregnancies. The mean age at the arthroplasty was twenty-nine years (range, twenty-two to thirty-eight years), and the mean time from the hip arthroplasty to the pregnancy was 2.5 years (range, one to seven years). These patients (Group A) were compared with a matched group of five women with a total of eight uncemented total hip prostheses (Group B) who had not completed a pregnancy. The mean follow-up time was eight years (range, two to thirteen years) for Group A and seven years (range, two to twelve years) for Group B. Patients were clinically evaluated with the Harris hip score. Radiographs were evaluated for component fixation and osteolysis. RESULTS The five women completed a total of six successful pregnancies. One patient, with a bilateral total hip arthroplasty, had two successful pregnancies, 2.5 years apart. Three children were delivered vaginally (with the mother in the lithotomy position) and three, by cesarean section. There were no complications related to the total hip arthroplasty after delivery. The mean weight gain during the pregnancy was 13 kg (range, 8 to 14.2 kg). In Group A, the mean Harris hip score was 94 points prior to the pregnancy and 97 points at the time of the most recent follow-up. In group B, the mean Harris hip score was 91 points at one to two years after the arthroplasty and it was unchanged at the time of the most recent follow-up. There were six excellent results and one good result of the hip arthroplasty in Group A and five excellent and three good results in Group B. The mean total arc of hip motion was 217 degrees in Group A before the pregnancy and 241 degrees at the time of the most recent follow-up. The mean total arc of hip motion was 193 degrees in Group B at one to two years postoperatively and 190 degrees at the time of the most recent follow-up. The difference in the total arc of hip motion between the two groups at the latest follow-up evaluation was significant (p = 0.025). There were no reoperations in either group. Radiographs showed osteolysis of the femur in three hips in Group A and three hips in Group B. CONCLUSIONS It appears that successful pregnancy and normal vaginal delivery can occur safely after total hip arthroplasty. The overall result, function, and radiographic appearance after the total hip arthroplasty was not adversely affected by pregnancy in this small group of patients.
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Affiliation(s)
- C M McDowell
- Department of Orthopaedics, University of North Carolina School of Medicine, Chapel Hill 27599, USA
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21
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Wood ML, McDowell CM, Kerstetter TL, Kelley SS. Open reduction and cementation for femoral head fracture secondary to avascular necrosis: preliminary report. Iowa Orthop J 2000; 20:17-23. [PMID: 10934620 PMCID: PMC1888752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Current treatment for femoral head avascular necrosis has shown good results in early stages of disease, but are not as impressive after progression to collapse. We treated 19 patients (20 hips) with Stage III avascular necrosis (AVN) by open reduction augmented by methylmethacrylate cementation. Follow up ranges from 6 months to 2 years (average = 8.7 months). We followed patient progress with pre- and post-operative Harris Hip Scores, Womac Osteoarthritis Index and a Health Status Questionnaire (SF36). All patients realized immediate post-operative pain relief and improvement in function. Harris Hip, Womac Osteoarthritis Index and SF36 physical health scores improved significantly from 54.0 to 79.5 (p < 0.05), 54.3 to 29.8 (p < 0.05) and 28.4 to 42.4 (p < 0.05), respectively. Three patients had a conversion to total hip arthroplasty. Cementation is technically simple, burns no bridges and enables patients a rapid recovery. The long term results, in regards to progression of disease and secondary arthritis, are unknown.
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Affiliation(s)
- M L Wood
- Department of Orthopaedic Surgery, University of North Carolina at Chapel Hill 27599-7055, USA
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McDowell CM, Anderson LH, Lemenager RP, Mangione DA, Day ML. Development of a progestin-based estrus synchronization program: II. Reproductive response of cows fed melengestrol acetate for 14 days with injections of progesterone and prostaglandin F2alpha. J Anim Sci 1998; 76:1273-9. [PMID: 9621933 DOI: 10.2527/1998.7651273x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We tested the efficacy of an estrus control system designed to provide optimal control of follicular development. In Exp. 1, postpartum cows (n = 133) and yearling heifers (n = 57) were fed either .5 mg x female(-1) x d(-1) of melengestrol acetate (MGA) or the carrier for MGA from d -13 to d 0 (d 0 = last day of MGA feeding). All females received 25 mg of PGF2alpha (i.m.) on d -13 and 0. On d -6, cows and heifers fed MGA were administered an i.m. injection of progesterone (200 mg; MGA/P4), and those fed the corn carrier (2XPGF2alpha) received no progesterone. Beginning on d 1, females were bred by AI from d 1 to at least d 5. During the estrus synchronization period (d 1 to d 5), more (P < .05) postpartum cows were observed in estrus (70.1 vs 42.4%), the timing of estrus was more (P < .05) precise, conception rate was similar, and pregnancy rate was higher (P < .05) in the MGA/P4 than in the 2XPGF2alpha treatment. More (P < .05) cows that were anestrous at the beginning of the breeding season were in estrus during the synchronization period in the MGA/P4 (55.8%) than in the 2XPGF2alpha (28.6%) treatment. In heifers, estrus was synchronized in over 90% of females, and neither conception nor pregnancy rate during the synchronization period differed between treatments. In Exp. 2, postpartum cows (n = 122) and heifers (n = 84) received treatments (MGA/P4 or 2XPGF2alpha) as described for Exp. 1 with one exception. In the MGA/ P4 treatment, progesterone was administered on d -7 rather than d -6. Females were bred by AI from d 1 to 5. The estrus response and conception rate during the synchronization period did not differ between treatments for either cows or heifers. We conclude that the progestin-based estrous synchronization system used in this study effectively synchronized an estrus of normal fertility in cyclic cows and induced a majority of anestrous cows to reinitiate estrous cycles.
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Affiliation(s)
- C M McDowell
- Department of Animal Sciences, The Ohio State University, Columbus 43210, USA
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McDowell CM, Anderson LH, Kinder JE, Day ML. Duration of treatment with progesterone and regression of persistent ovarian follicles in cattle. J Anim Sci 1998; 76:850-5. [PMID: 9535347 DOI: 10.2527/1998.763850x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The objective of the present study was to determine the duration of elevated concentrations of progesterone necessary to induce atresia of persistent ovarian follicles. Heifers were administered 25 mg of PGF2alpha on d 6 and 7 (d 0 = d of synchronized estrus) and a norgestomet implant from d 6 to 14. Ovaries were monitored by ultrasonography, and blood samples were collected on d 3, 5, 7, 9, 11, and 12 and daily from d 14 until ovulation. On d 12, heifers received either two progesterone-releasing intravaginal devices (PRID) for 6 h (6-h; n = 5), two PRID for 24 h (24-h; n = 5), or no treatment (CON; n = 5). Blood samples were collected at 15-min intervals from h -6 to 30 (PRID insertion = h 0) and analyzed for concentrations of LH. Characteristics of LH secretion were determined for consecutive 6-h periods (Period 0 to 5). Hourly blood samples, collected from h 0 to 29, were analyzed for concentrations of 17beta-estradiol (estradiol) and progesterone. The dominant ovarian follicles present on d 7 increased in size to 15.4+/-.3 mm on d 12 ("persistent follicle"). Following removal of the PRID and norgestomet implants, atresia of persistent follicles and ovulation of new follicles were induced in one of five and in four of five heifers in the 6-h and 24-h treatments, respectively. Persistent follicles ovulated after withdrawal of norgestomet in all other heifers. Concentrations of progesterone were increased from h 1 to 7 in the 6-h and h 1 to 26 in the 24-h treatment. Frequency of LH pulses was reduced (P < .05) during Periods 1 to 2 in the 6-h and Periods 1 to 5 in the 24-h treatment relative to the CON treatment. By h 10, concentrations of estradiol in the 6-h and 24-h treatments were lower (P < . 05) than in the CON treatment. This suppression continued through h 29 in the 24-h treatment (P < .05), whereas concentrations in the 6-h treatment were intermediate to those of the CON and 24-h treatments after h 14. Suppression of pulsatile LH release and estradiol secretion was evident with 6 and 24 h of treatment with progesterone, but only the 24-h treatment induced atresia of persistent follicles in a majority of the heifers.
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Affiliation(s)
- C M McDowell
- Department of Animal Sciences, The Ohio State University, Columbus 43210, USA
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24
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Abstract
Two experiments were designed to investigate the endocrine mechanisms by which progestin administration induces puberty in heifers. In experiment 1, prepubertal heifers were randomly assigned by age to receive either a single norgestomet implant for 10 days (NORG; n = 15) or to serve as unimplanted controls (CONT; n = 14). Serial blood samples were obtained on Days -0.5, 8.5, and 10.5 (Day 1 = day of implant insertion) and were analyzed for concentrations of LH. On days 9 and 11, 4 heifers in each treatment were slaughtered, and the reproductive tracts were obtained. Weekly progesterone analyses were performed to estimate the day of puberty in heifers not slaughtered. Puberty was induced in 6 of 7 heifers in the NORG treatment, resulting in an earlier (p < 0.05) day of puberty in the NORG than in the CONT treatment. The frequency of LH pulses was higher (p < 0.05) on Days 8.5 and 10.5 in the NORG as compared to the CONT treatment. Although no difference (p > 0.10) was observed between treatments in follicular development, uterine weight was greater (p < 0.05) in NORG than in CONT heifers on Day 11. In experiment 2, prepubertal heifers (n = 47) were administered either 1 (1NORG; n = 16), 3(3NORG; n = 16), or 0 (CONT; n = 15) norgestomet implants for 10 days, and serial blood samples were obtained as described for experiment 1. Transrectal ultrasonography was used to determine the diameter of the largest follicle on Day 9. Plasma samples were obtained after each serial sample collection period and were analyzed for estradiol concentrations. Puberty was induced in 75% (12 of 16) and 81% (13 of 16) of heifers in the 1NORG treatments, respectively. Four heifers in the 1NORG treatment, from which serial blood samples were collected, ovulated before removal of the progestin implant, and the LH data for this treatment were deleted. In the 3NORG treatment, LH pulse frequency was suppressed (p < 0.05) on Day 8.5, but was greater (p < 0.05) 12 h after removal of the progestin (Day 10.5) than in the CONT treatment. We conclude that progestin administration hastens puberty by increasing LH secretion after progestin withdrawal and propose that progestin administration induces puberty by accelerating the peripubertal decrease of estradiol negative feedback on LH secretion.
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Affiliation(s)
- L H Anderson
- Department of Animal Science, Ohio State University, Columbus 43210, USA
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McDowell CM, Ross MH. Dietary fat, age and hepatic alkaline phosphatase activity in the rat. Growth 1966; 30:177-85. [PMID: 5963696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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