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Mehta R, Ray RM, Tussing-Humphreys LM, Pasquale LR, Maki P, Haan MN, Jackson R, Vajaranant TS. Effect of Low-Fat Dietary Modification on Incident Open-Angle Glaucoma. Ophthalmology 2022; 130:565-574. [PMID: 36410561 DOI: 10.1016/j.ophtha.2022.11.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 10/10/2022] [Accepted: 11/14/2022] [Indexed: 11/23/2022] Open
Abstract
PURPOSE We tested whether dietary modification (DM) altered the risk for incident primary open-angle glaucoma (POAG). DESIGN Secondary analysis of a randomized intervention trial. PARTICIPANTS We linked Medicare claims data to 45 203 women in the Women's Health Initiative Dietary Modification Trial, of which 23 776 participants were enrolled in fee-for-service Medicare Part B and had physician claims. METHODS Women were randomized to follow either DM (a low-fat diet, with increased vegetable, fruit, and grain intake) or their usual diet without modification. Nine thousand three hundred forty women were randomized to the DM intervention, whereas 13 877 women were randomized to the control group. Our analyses were based on an intention-to-treat design, with a follow-up to the end of continuous Medicare coverage, death, or the last clams date (12/31/2018), whichever occurred first. Primary open-angle glaucoma was defined as the first claim with the International Classification of Diseases, Ninth or Tenth Revision, codes. Dietary data were assessed using a food frequency questionnaire. MAIN OUTCOME MEASURES We used Cox proportional hazards models to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for risk of POAG. Subgroup analyses were performed with P values for interaction. RESULTS After exclusion of women with Medicare-derived glaucoma before randomization, the final analysis included 23 217 women (mean age, 64.4 ± 5.8 years). Baseline characteristics were balanced between the intervention and control groups. Primary open-angle glaucoma incidence was 11.1 per 1000 woman-years (mean follow-up, 11.6 ± 7.4 years; mean DM duration, 5.2 ± 3.2 years). We found no overall benefit of DM in reducing incident POAG (HR, 1.04; 95% CI, 0.96-1.12). Race and participant age did not modify this relation (P = 0.08 and P = 0.24 for interaction, respectively). In further analysis of baseline nutrient and food intake stratified by quartile groups, risk of open-angle glaucoma (OAG) in DM participants in the lowest quartile group for percentage calories (kilocalories) from total fat (33.8 or lower) was increased (HR, 1.22; 95% CI, 1.05-1.41; P = 0.007 for interaction). CONCLUSIONS Analysis suggests that DM in participants in the lowest quartile group for percentage calories from total fat at baseline increased the risk of incident OAG among women regardless of age or race. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found after the references.
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Affiliation(s)
- Rajvi Mehta
- Illinois Eye and Ear Infirmary, University of Illinois at Chicago, Chicago, Illinois
| | - Roberta M Ray
- Women's Health Initiative, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Lisa Marie Tussing-Humphreys
- Illinois Eye and Ear Infirmary, University of Illinois at Chicago, Chicago, Illinois; Applied Health Sciences, University of Illinois at Chicago, Chicago, Illinois
| | - Louis R Pasquale
- New York Eye and Ear Infirmary of Mount Sinai, New York, New York
| | - Pauline Maki
- Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois
| | - Mary N Haan
- University of California, San Francisco, San Francisco, California
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O'Callaghan J, Cassidy PS, Humphries P. Open-angle glaucoma: therapeutically targeting the extracellular matrix of the conventional outflow pathway. Expert Opin Ther Targets 2017; 21:1037-1050. [PMID: 28952395 DOI: 10.1080/14728222.2017.1386174] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
INTRODUCTION Ocular hypertension in open-angle glaucoma is caused by a reduced rate of removal of aqueous humour (AH) from the eye, with the majority of AH draining from the anterior chamber through the conventional outflow pathway, comprising the trabecular meshwork (TM) and Schlemm's Canal. Resistance to outflow is generated, in part, by the extracellular matrix (ECM) of the outflow tissues. Current pressure-lowering topical medications largely suppress AH production, or enhance its clearance through the unconventional pathway. However, therapies targeting the ECM of the conventional pathway in order to decrease intraocular pressure have become a recent focus of attention. Areas covered: We discuss the role of ECM of the TM in outflow homeostasis and its relevance as a target for glaucoma therapy, including progress in development of topical eye formulations, together with gene therapy approaches based on inducible, virally-mediated expression of matrix metalloproteinases to enhance aqueous outflow. Expert opinion: There remains a need for improved glaucoma medications that more specifically act upon sites causative to glaucoma pathogenesis. Emerging strategies targeting the ECM of the conventional outflow pathway, or associated components of the cytoskeleton of TM cells, involving new pharmacological formulations or genetically-based therapies, are promising avenues of future glaucoma treatment.
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Affiliation(s)
- Jeffrey O'Callaghan
- a Ocular Genetics Unit, Smurfit Institute of Genetics , University of Dublin, Trinity College , Dublin , Ireland
| | - Paul S Cassidy
- a Ocular Genetics Unit, Smurfit Institute of Genetics , University of Dublin, Trinity College , Dublin , Ireland
| | - Pete Humphries
- a Ocular Genetics Unit, Smurfit Institute of Genetics , University of Dublin, Trinity College , Dublin , Ireland
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Kang JH, Willett WC, Rosner BA, Buys E, Wiggs JL, Pasquale LR. Association of Dietary Nitrate Intake With Primary Open-Angle Glaucoma: A Prospective Analysis From the Nurses' Health Study and Health Professionals Follow-up Study. JAMA Ophthalmol 2016; 134:294-303. [PMID: 26767881 DOI: 10.1001/jamaophthalmol.2015.5601] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
IMPORTANCE Nitric oxide signaling alterations in outflow facility and retinal blood flow autoregulation are implicated in primary open-angle glaucoma (POAG). Nitric oxide donation has emerged as a POAG therapeutic target. An exogenous source of nitric oxide is dietary nitrates. OBJECTIVE To evaluate the association between dietary nitrate intake, derived mainly from green leafy vegetables, and POAG. DESIGN, SETTING, AND PARTICIPANTS We followed up participants biennially in the prospective cohorts of the Nurses' Health Study (63 893 women; 1984-2012) and the Health Professionals Follow-up Study (41 094 men; 1986-2012) at each 2-year risk period. Eligible participants were 40 years or older, were free of POAG, and reported eye examinations. EXPOSURES The primary exposure was dietary nitrate intake. Information on diet and potential confounders was updated with validated questionnaires. MAIN OUTCOMES AND MEASURES The main outcome was the incidence of POAG and POAG subtypes; 1483 cases were confirmed with medical records and classified into subtypes defined by intraocular pressure (IOP) (≥22 or <22 mm Hg) or by visual field (VF) loss pattern at diagnosis (peripheral loss only or early paracentral loss). Cohort-specific and pooled multivariable rate ratios (MVRRs) and 95% CIs were estimated. RESULTS During 1 678 713 person-years of follow-up, 1483 incident cases of POAG were identified. The mean (SD) age for the 1483 cases was 66.8 (8.3). Compared with the lowest quintile of dietary nitrate intake (quintile 1: approximately 80 mg/d), the pooled MVRR for the highest quintile (quintile 5: approximately 240 mg/d) was 0.79 (95% CI, 0.66-0.93; P for trend = .02). The dose response was stronger (P for heterogeneity = .01) for POAG with early paracentral VF loss (433 cases; quintile 5 vs quintile 1 MVRR = 0.56; 95% CI, 0.40-0.79; P for trend < .001) than for POAG with peripheral VF loss only (835 cases; quintile 5 vs quintile 1 MVRR = 0.85; 95% CI, 0.68-1.06; P for trend = .50). The association did not differ (P for heterogeneity = .75) by POAG subtypes defined by IOP (997 case patients with IOP ≥22 mm Hg: quintile 5 vs quintile 1 MVRR = 0.82; 95% CI, 0.67-1.01; P for trend = .11; 486 case patients with IOP <22 mm Hg: quintile 5 vs quintile 1 MVRR = 0.71; 95% CI, 0.53-0.96; P for trend = .12). Green leafy vegetables accounted for 56.7% of nitrate intake variation. Compared with consuming 0.31 servings per day, the MVRR for consuming 1.45 or more servings per day was 0.82 for all POAG (95% CI, 0.69-0.97; P for trend = .02) and 0.52 for POAG with paracentral VF loss (95% CI, 0.29-0.96; P for trend < .001). CONCLUSIONS AND RELEVANCE Higher dietary nitrate and green leafy vegetable intake was associated with a lower POAG risk, particularly POAG with early paracentral VF loss at diagnosis.
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Affiliation(s)
- Jae H Kang
- Channing Division of Network Medicine, Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts
| | - Walter C Willett
- Channing Division of Network Medicine, Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts2Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts3Department of Epidemiology, Harvard
| | - Bernard A Rosner
- Channing Division of Network Medicine, Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts4Department of Biostatistics, Harvard School of Public Health, Boston, Massachusetts
| | - Emmanuel Buys
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital Research Institute, Boston
| | - Janey L Wiggs
- Glaucoma Service, Massachusetts Eye and Ear Infirmary, Boston
| | - Louis R Pasquale
- Channing Division of Network Medicine, Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts6Glaucoma Service, Massachusetts Eye and Ear Infirmary, Boston
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Edwards G, Aribindi K, Guerra Y, Bhattacharya SK. Sphingolipids and ceramides of mouse aqueous humor: Comparative profiles from normotensive and hypertensive DBA/2J mice. Biochimie 2014; 105:99-109. [PMID: 25014247 DOI: 10.1016/j.biochi.2014.06.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 06/25/2014] [Indexed: 11/17/2022]
Abstract
PURPOSE To identify the sphingolipid and ceramide species and their quantitative differences between normotensive and hypertensive intraocular pressure states in DBA/2J mouse aqueous humor (AH). METHODS Normotensive and hypertensive AH was sampled from mice by paracentesis. Lipid extraction was performed using modifications of the Bligh and Dyer method. Protein concentration was estimated using the Bradford colorimetric assay. Sphingolipids and ceramides were identified and subjected to ratiometric quantification using appropriate class specific lipid standards on a TSQ Quantum Access Max triple quadrupole mass spectrometer. RESULTS The comparative profiles of normotensive and hypertensive DBA/2J mouse AH showed several species of sphingomyelin, sphingoid base, sphingoid base-1-phosphate (S1P) and ceramides common between them. A number of unique lipids in each of the above lipid classes were also identified in normotensive AH that were absent in hypertensive AH and vice versa. CONCLUSION A number of sphingolipid and ceramide species were found to be uniquely present in normotensive, but absent in hypertensive AH and vice versa. Further pursuit of these findings is likely to contribute towards expanding our understanding of the molecular changes associated with increased intraocular pressure (IOP) and glaucoma.
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Affiliation(s)
- Genea Edwards
- Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, FL 33136, USA
| | - Katyayini Aribindi
- Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, FL 33136, USA
| | - Yenifer Guerra
- Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, FL 33136, USA
| | - Sanjoy K Bhattacharya
- Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, FL 33136, USA.
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Rao PV. Bioactive lysophospholipids: role in regulation of aqueous humor outflow and intraocular pressure in the context of pathobiology and therapy of glaucoma. J Ocul Pharmacol Ther 2014; 30:181-90. [PMID: 24283588 PMCID: PMC3991961 DOI: 10.1089/jop.2013.0194] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 10/23/2013] [Indexed: 01/21/2023] Open
Abstract
Homeostasis of aqueous humor (AH) outflow and intraocular pressure (IOP) is essential for normal vision. Impaired AH outflow through the trabecular meshwork (TM) and a resultant elevation in IOP are common changes in primary open-angle glaucoma (POAG), which is the most prevalent form of glaucoma. Although elevated IOP has been recognized as a definitive risk factor for POAG and lowering elevated IOP remains a mainstay for glaucoma treatment, little is known about the molecular mechanisms, especially external cues and intracellular pathways, involved in the regulation of AH outflow in both normal and glaucomatous eyes. In addition, despite the recognition that increased resistance to AH outflow via the conventional pathway consisting of TM and Schlemm's canal is the main cause for elevated IOP, there are no clinically approved drugs that target the conventional pathway to lower IOP in glaucoma patients. The aim of this article is to briefly review published work on the importance of bioactive lysophospholipids (eg, lysophosphatidic acid and sphingosine-1-phosphate), their receptors, metabolism, signaling, and role in the regulation of AH outflow via the TM and IOP, and to discuss pharmacological targeting of key proteins in the lysophospholipid signaling pathways to lower IOP in glaucoma patients.
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Affiliation(s)
- Ponugoti Vasantha Rao
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina
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Guerra Y, Aljohani AJ, Edwards G, Bhattacharya SK. A comparison of trabecular meshwork sphingolipids and ceramides of ocular normotensive and hypertensive states of DBA/2J mice. J Ocul Pharmacol Ther 2013; 30:283-90. [PMID: 24320088 DOI: 10.1089/jop.2013.0168] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
PURPOSE To determine the differential profiles of sphingomyelin, sphingoid base, sphingoid base-1-phosphate, and ceramide and their quantitative differences between trabecular meshwork (TM) derived from normotensive and hypertensive intraocular pressure states of DBA/2J mice. METHODS Normotensive and hypertensive state TM were collected from mice and analyzed. Lipid extraction was performed using the Bligh and Dyer method, and the protein concentrations were determined using the Bradford method. The lipids were identified and quantified using appropriate standards with a TSQ Quantum Access Max triple quadrupole mass spectrometer applying class-specific lipid identification settings. RESULTS The comparative profiles of sphingomyelin, sphingoid base, sphingoid base-1-phosphate, and ceramide between normotensive and hypertensive TM showed several species unique to a phase and as well common between states. CONCLUSION The presence or absence of several sphingolipids and ceramides in the normotensive or hypertensive states may contribute to better understanding of the glaucomas.
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Affiliation(s)
- Yenifer Guerra
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine , Miami, Florida
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Rogers ME, Navarro ID, Perkumas KM, Niere SM, Allingham RR, Crosson CE, Stamer WD. Pigment epithelium-derived factor decreases outflow facility. Invest Ophthalmol Vis Sci 2013; 54:6655-61. [PMID: 24030458 DOI: 10.1167/iovs.13-12766] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
PURPOSE Pigment epithelium-derived factor (PEDF) regulates blood-retinal barrier function. As a constituent of aqueous humor, the role of PEDF in conventional outflow function is unknown. The goals of the study were to examine the effects of PEDF on barrier function of cultured Schlemm's canal (SC) endothelia and outflow facility in mouse eyes in situ. METHODS To model the inner wall of SC, transendothelial electrical resistance (TEER) of human SC and porcine angular aqueous plexus (AAP) cells was monitored. To examine an intact conventional outflow pathway, enucleated eyes from culled C57BL/6 mice were perfused with PEDF using a computer-controlled system. Purified PEDF (0.1 and 1 μg/mL) was perfused at four different pressure steps (4, 8, 15, 20 mm Hg), measuring flow to determine outflow facility (slope of flow/pressure relationship). RESULTS Pigment epithelium-derived factor increased TEER of porcine AAP cells in a dose-dependent fashion (0.3-3 μg/mL), and 1 μg/mL recombinant PEDF or conditioned media from pigmented retinal pigment epithelial monolayers stabilized TEER of human SC monolayers over time (0-48 hours). In perfusion experiments, we observed a 43.7% decrease in outflow facility (0.016 vs. 0.029 μL/min/mm Hg, P = 4.5 × 10⁻⁵) in eyes treated with 1 μg/mL PEDF compared to vehicle-perfused controls, and a 19.9% decrease (0.021 vs. 0.027 μL/min/mm Hg, P = 0.003) at 100 ng/mL PEDF. CONCLUSIONS Pigment epithelium-derived factor increased barrier function in both the in vitro and in situ models of the inner wall of SC. Modification of PEDF signaling in SC cells may be therapeutically exploited to increase outflow facility in people with ocular hypertension or decrease outflow facility in those with hypotony.
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Affiliation(s)
- Morgan E Rogers
- Department of Ophthalmology, Duke University, Durham, North Carolina
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Sphingolipids and ceramides in human aqueous humor. Mol Vis 2013; 19:1966-84. [PMID: 24068864 PMCID: PMC3782370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 09/17/2013] [Indexed: 11/23/2022] Open
Abstract
PURPOSE To determine the differential profiles of sphingomyelin, sphingoid base, sphingoid base-1-phosphate and ceramide lipid species and their quantitative differences between control and glaucomatous aqueous humor (AQH) derived from human donors. METHODS AQH from control and primary open-angle glaucoma donors was collected and subjected to lipid extraction using suitable modifications of the Bligh and Dyer method. Proteins were estimated using Bradford's method. Lipids were identified and ratiometrically quantified in a two-step process using precursor ion scan or neutral loss scan (NLS) with appropriate class-specific lipid standards on a TSQ Quantum Access Max mass spectrometer following established procedures. Primary human trabecular meshwork cells and video microscopic imaging were used to assess changes in cell shape and motility upon exposure to 20 pmol of Cer(d18:0/18:1(9Z)) in 10% dimethyl sulfoxide (vehicle). RESULTS We identified several species of sphingomyelin, sphingoid base, sphingoid base-1-phosphate, and ceramides that were common between control and glaucomatous AQH. Some unique lipid species in these classes were also identified in controls but not in glaucoma and vice versa. We found exposure to 20 pmol of Cer(d18:0/18:1(9Z)) resulted in changes in the trabecular meshwork cell shape and observed motility changes compared to vehicle-only control. CONCLUSIONS Most lipids belonging to the sphingomyelin, sphingoid base, sphingoid base-1-phosphate, and ceramide species were common between control and primary open-angle glaucoma donors. However, some sphingolipids and ceramides were found to be uniquely present in control but absent in the glaucomatous AQH and vice versa. Identification of unique lipid species present or absent in the pathophysiological context may contribute further insight into glaucoma pathology.
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Abstract
PURPOSE OF REVIEW Regulation of intraocular pressure by the conventional (trabecular) outflow pathway is complicated, involving a myriad of mechanical and chemical signals. In most, intraocular pressure is maintained within a tight range over a lifetime. Unfortunately in some, dysfunction results in ocular hypertension and open-angle glaucoma. In the context of established knowledge, this review summarizes recent investigations of conventional outflow function, with the goal of identifying areas for future inquiry and therapeutic targeting. RECENT FINDINGS Mechanical stimulation of conventional outflow cells due to intraocular pressure fluctuations impacts contractility, gene expression, pore formation, enzyme activity, and signaling. Numerous local signaling mediators in the conventional pathway such as bioactive lipids, cytokines, nitric oxide, and nucleotides participate in the regulation of outflow. Interestingly outflow through the conventional pathway is not uniform, but segmental, with passageways constantly changing due to focal protease activity of trabecular cells clearing extracellular matrix materials. The relationship between extracellular matrix expression and trabecular meshwork contractility appears to coordinately impact outflow resistance and is the target of a new class of drugs, the Rho kinase inhibitors. SUMMARY The conventional outflow pathway is a dynamic, pressure-sensitive tissue that is vulnerable to pathology on many fronts, each representing a therapeutic opportunity.
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Bucolo C, Salomone S, Drago F, Reibaldi M, Longo A, Uva MG. Pharmacological management of ocular hypertension: current approaches and future prospective. Curr Opin Pharmacol 2013; 13:50-5. [PMID: 23069477 DOI: 10.1016/j.coph.2012.09.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 09/18/2012] [Accepted: 09/21/2012] [Indexed: 01/11/2023]
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Boussommier-Calleja A, Bertrand J, Woodward DF, Ethier CR, Stamer WD, Overby DR. Pharmacologic manipulation of conventional outflow facility in ex vivo mouse eyes. Invest Ophthalmol Vis Sci 2012; 53:5838-45. [PMID: 22807298 DOI: 10.1167/iovs.12-9923] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PURPOSE Mouse models are useful for glaucoma research, but it is unclear whether intraocular pressure (IOP) regulation in mice operates through mechanisms similar to those in humans. Our goal was to determine whether pharmacologic compounds that affect conventional outflow facility in human eyes exert similar effects in C57BL/6 mice. METHODS A computerized perfusion system was used to measure conventional outflow facility in enucleated mouse eyes ex vivo. Paired eyes were perfused sequentially, either immediately after enucleation or after 3 hours storage at 4°C. Three groups of experiments examined sphingosine 1-phosphate (S1P), S1P with antagonists to S1P(1) and S1P(2) receptors, and the prostanoid EP(4) receptor agonist 3,7-dithia PGE(1). We also examined whether a 24-hour postmortem delay affected the response to 3,7-dithia prostaglandin E(1) (PGE(1)). RESULTS S1P decreased facility by 39%, and was blocked almost completely by an S1P(2), but not S1P(1), receptor antagonist. The S1P(2) receptor antagonist alone increased facility nearly 2-fold. 3,7-dithia PGE(1) increased facility by 106% within 3 hours postmortem. By 24 hours postmortem, the facility increase caused by 3,7-dithia PGE(1) was reduced 3-fold, yet remained statistically detectable. CONCLUSIONS C57BL/6 mice showed opposing effects of S1P(2) and EP(4) receptor activation on conventional outflow facility, as observed in human eyes. Pharmacologic effects on facility were detectable up to 24 hours postmortem in enucleated mouse eyes. Mice are suitable models to examine the pharmacology of S1P and EP(4) receptor stimulation on IOP regulation as occurs within the conventional outflow pathway of human eyes, and are promising for studying other aspects of aqueous outflow dynamics.
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Yoshikawa K, Takei S, Hasegawa-Ishii S, Chiba Y, Furukawa A, Kawamura N, Hosokawa M, Woodward DF, Watanabe K, Shimada A. Preferential localization of prostamide/prostaglandin F synthase in myelin sheaths of the central nervous system. Brain Res 2010; 1367:22-32. [PMID: 20950588 DOI: 10.1016/j.brainres.2010.10.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2010] [Revised: 10/05/2010] [Accepted: 10/06/2010] [Indexed: 10/19/2022]
Abstract
Prostaglandin (PG) F(₂α) is a product of cyclooxygenase (COX)-catalyzed metabolism of arachidonic acid and exerts biological functions in various tissues. Prostaglandin ethanolamide (prostamide) F(₂α) is a COX-2-catalyzed metabolite of arachidonoyl ethanolamide (anandamide) that induces pharmacological actions in ocular tissues. Although PGF(₂α) is one of the most abundant prostaglandins in the brain, function of PGF(₂α) in the central nervous system (CNS) has not been extensively investigated. Recently identified prostamide/PGF synthase catalyzes the reductions of prostamide H₂ to prostamide F(₂α) and PGH₂ to PGF(₂α), chiefly in the CNS. We examined tissue distribution of the enzyme in the CNS by immunohistochemistry, double immunofluorescence, and immuno-electron microscopy. We confirmed histological findings by immunofluorescence analyses of brain cell cultures. Prostamide/PGF synthase was expressed preferentially in the white matter bundles of the entire CNS of adult mice with less marked expression in neuronal cell bodies. The enzyme was colocalized with myelin basic protein (MBP) in myelin sheaths but not in axons. At the ultrastructural level, the enzyme was localized to myelin sheaths. Expression of the enzyme increased between P9 and P14 during the postnatal development, presumably in accordance with myelinogenesis. Cultured oligodendrocytes at 7 days in vitro expressed the enzyme in cytoplasmic processes where the enzyme was colocalized with MBP. Immunoreactivity for COX-2 was detected in white matter and cultured oligodendrocytes. Relatively selective localization of prostamide/PGF synthase suggests that myelin sheaths of the CNS may serve as the sites for producing prostamide F(₂α) and/or PGF(₂α), which may contribute to the formation and maintenance of central myelin.
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Affiliation(s)
- Keisuke Yoshikawa
- Department of Pathology, Institute for Developmental Research, Aichi Human Service Center, 713-8 Kamiya, Kasugai, Aichi 480-0892, Japan
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Smid SD. Role of prostaglandins and specific place in therapy of bimatoprost in the treatment of elevated intraocular pressure and ocular hypertension: A closer look at the agonist properties of bimatoprost and the prostamides. Clin Ophthalmol 2009; 3:663-70. [PMID: 20054414 PMCID: PMC2801635 DOI: 10.2147/opth.s6337] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Indexed: 11/23/2022] Open
Abstract
Bimatoprost is the only representative of a novel class of prostaglandin ethanolamide (prostamide) compounds used therapeutically as an efficacious treatment for glaucoma. The pathways through which bimatoprost works to improve uveoscleral outflow to relieve elevated intraocular pressure are similar to those of the conventional prostaglandins used in glaucoma therapy, with some evidence of a preferential action at the trabecular meshwork. The pharmacology of bimatoprost is however, unclear. Pharmacological evidence supports a specific and distinct receptor-mediated agonist activity of bimatoprost at ‘prostamide’ receptors, which is selective to the prostamides as a class. However, other studies have reported either activity of bimatoprost at additional prostanoid and nonprostanoid receptors, or a conversion of bimatoprost to metabolites with agonist activity at prostaglandin FP receptors in the human eye. The formation of endogenous prostamides has been demonstrated in vivo, by a novel pathway involving the cyclooxygenase-2-mediated conversion of endogenous cannabinoid (endocannabinoid) substrates. Irrespective of the pharmacology of bimatoprost and the prostamides in general, further studies are needed to determine the biological role and biochemical pathology of prostamides in the human eye, particularly in glaucoma. Such studies may improve our understanding of uveoscleral flow and may offer new treatments for controlling intraocular pressure.
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Affiliation(s)
- Scott D Smid
- Discipline of Pharmacology, School of Medical Sciences, Faculty of Health Sciences, University of Adelaide, Adelaide, SA, Australia.
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Stamer WD, Read AT, Sumida GM, Ethier CR. Sphingosine-1-phosphate effects on the inner wall of Schlemm's canal and outflow facility in perfused human eyes. Exp Eye Res 2009; 89:980-8. [PMID: 19715693 DOI: 10.1016/j.exer.2009.08.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 08/18/2009] [Accepted: 08/18/2009] [Indexed: 11/29/2022]
Abstract
Previous work has shown that sphingosine 1-phosphate (S1P) decreases outflow facility in perfused porcine eyes while dramatically increasing giant vacuole density in the inner wall of the aqueous plexus, with no obvious changes in the trabecular meshwork (TM). Due to known effects of S1P on cell-cell junction assembly in vascular endothelia, we hypothesized that S1P would decrease outflow facility in human eyes by increasing the complexity of cell-cell junctions in Schlemm's canal (SC) inner wall endothelia. Perfusion of enucleated post mortem human eyes at 8 mmHg constant pressure in the presence or absence of 5 microM S1P showed that S1P decreased outflow facility by 36 +/- 20% (n = 10 pairs; p = 0.0004); an effect likely mediated by activation of S1P(1) and/or S1P(3) receptor subtypes, which were found to be the principal S1P receptors expressed by both TM and SC cells by RT-PCR, confocal immunofluorescence microscopy and western blot analyses. Examination of SC's inner wall using confocal microscopy revealed no consistent differences in VE-cadherin, beta-catenin, phosphotyrosine or filamentous actin abundance/distribution between S1P-treated eyes and controls. Moreover, morphological inspection of conventional outflow tissues by light and scanning electron microscopy showed no significant differences between S1P-treated and control eyes, particularly in giant vacuole density. Thus, unlike the situation in porcine eyes, we did not observe changes in inner wall morphology in human eyes treated with S1P, despite a significant and immediate decrease in outflow facility in both species. Regardless, S1P receptor antagonists represent novel therapeutic prospects for ocular hypertension in humans.
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Affiliation(s)
- W Daniel Stamer
- Department of Ophthalmology and Vision Science, The University of Arizona, 655 North Alvernon Way, Suite 108, Tucson, AZ 85711, USA.
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