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Uchida T, Shimizu S, Yamagishi R, Tokuoka SM, Kita Y, Sakata R, Honjo M, Aihara M. TRPV4 is activated by mechanical stimulation to induce prostaglandins release in trabecular meshwork, lowering intraocular pressure. PLoS One 2021; 16:e0258911. [PMID: 34673834 PMCID: PMC8530296 DOI: 10.1371/journal.pone.0258911] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 10/07/2021] [Indexed: 11/25/2022] Open
Abstract
Trabecular meshwork constitutes the conventional outflow pathway and controls intraocular pressure by regulating aqueous outflow. Mechanical stimulation has been studied as one of the triggers to regulate aqueous outflow in trabecular meshwork, but it is not well understood. We investigated that how transient receptor potential cation channel subfamily V member 4 (TRPV4) functions in human trabecular meshwork cells (HTMC) and affects intraocular pressure (IOP). HTMC were treated with TRPV4 siRNA, followed by incubation for 24 hours. We confirmed the suppression of TRPV4 mRNA expression and the reduction of Ca2+ influx by the TRPV4 agonist GSK1016790A in TRPV4 siRNA-treated HTMC. TRPV4 siRNA-treated HTMC exhibited a significant reduction in Ca2+ influx and production of arachidonic acid and prostaglandin (PG) E2 induced by mechanical stretch, and direct activation of TRPV4 by GSK1016790A increased production of arachidonic acid, PGE2, and PGD2 and inhibited gel contraction. Furthermore, TRPV4-deficient mice had higher IOP than wild-type mice, and GSK1016790A administration lowered IOP. These results suggest that TRPV4 mediates the cellular response induced by trabecular meshwork stretch, leading to IOP reduction through the production of prostaglandins and inhibition of cell contraction. Targeting TRPV4 may have therapeutic benefits that lead to lowering IOP in glaucoma patients.
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Affiliation(s)
- Takatoshi Uchida
- Department of Ophthalmology, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan
- Senju Laboratory of Ocular Science, Senju Pharmaceutical Co., Ltd., Kobe, Japan
| | - Shota Shimizu
- Department of Ophthalmology, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan
- Senju Laboratory of Ocular Science, Senju Pharmaceutical Co., Ltd., Kobe, Japan
| | - Reiko Yamagishi
- Department of Ophthalmology, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan
| | - Suzumi M. Tokuoka
- Department of Lipidomics, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan
| | - Yoshihiro Kita
- Department of Lipidomics, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan
- Life Science Core Facility, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan
| | - Rei Sakata
- Department of Ophthalmology, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan
| | - Megumi Honjo
- Department of Ophthalmology, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan
| | - Makoto Aihara
- Department of Ophthalmology, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan
- * E-mail:
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Angeli A, Supuran CT. Prostaglandin receptor agonists as antiglaucoma agents (a patent review 2013 - 2018). Expert Opin Ther Pat 2019; 29:793-803. [PMID: 31462124 DOI: 10.1080/13543776.2019.1661992] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Introduction: Elevated intraocular pressure (IOP) is the most prevalent risk factor for glaucoma. Prostaglandin analogs are a first-line therapy for glaucoma due to their ability to reduce IOP, once-daily dosing, efficacy, and minimal side-effect profile. Many compounds targeting different PG receptors have been developed in the last years, some of them being in clinical use. Latanoprost, Bimatoprost, Travoprost, and Tafluprost are clinically used as antiglaucoma drugs and act as agonists of the PGF2α receptor. The inability to fully understand the mechanism of action of clinically used PGF2α analogs is thus a strong driver for additional research into the mechanism of action of ocular hypotensive drugs belonging to this class of pharmacological agents. Areas covered: This review explores the last 5 years (2013-2018), where many patents describing new compounds acting on different prostaglandin receptors, and mainly targeting EP1-4 and FP receptors, were released. Expert opinion: To date, there has been a growing awareness over recent years of the therapeutic use of novel derivatives as new antiglaucoma pharmaceutical products. Patents involved in discovering new approaches and new molecules for the treatment of glaucoma diseases encouraged the scientific community to increase the variety of drugs available for the treatment of ocular diseases.
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Affiliation(s)
- Andrea Angeli
- NEUROFARBA Dept., Sezione di Scienze Farmaceutiche, University of Florence , Florence , Italy
| | - Claudiu T Supuran
- NEUROFARBA Dept., Sezione di Scienze Farmaceutiche, University of Florence , Florence , Italy
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Tu S, Li K, Hu D, Li K, Ge J. Posture-Dependent 24-Hour Intraocular Pressure Fluctuation Patterns in an Intraocular Hypertension Monkey Model. Transl Vis Sci Technol 2019; 8:63. [PMID: 31293817 PMCID: PMC6602140 DOI: 10.1167/tvst.8.3.63] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 03/04/2019] [Indexed: 11/24/2022] Open
Abstract
Purpose We investigate 24-hour intraocular pressure (IOP) fluctuation patterns and the influence of body position on IOP in a chronic ocular hypertension (COHT) monkey model. Methods We recorded 24-hour IOPs (nine time points) in the different body positions in 10 eyes with normal and eight with high IOP (with random selection of one eye of each monkey) using a Tonopen. The IOPs at various time points and in different body positions were compared. Results The average 24-hour IOPs in the immediate-supine, 10-minute supine, 10-minute seated, and immediate-seated positions in the COHT models were 28.64 ± 9.82, 25.42 ± 7.62, 23.49 ± 7.67, and 20.53 ± 7.80 mmHg, respectively. The diurnal-to-nocturnal IOP changes were 8.51 ± 2.93, 5.81 ± 3.67, 5.48 ± 2.97, and 3.59 ± 2.74 mmHg, respectively. The sudden shift between the supine and seated positions bring greater IOP variations (8.11 ± 2.85 mmHg) in the COHT monkeys, and the IOP fluctuations reached 14 to 38 mmHg when considering body position and the measurement time points. Conclusions The measurement time and body position influenced IOP. More elevated IOP occurred in the immediate-supine position and during the transient shift between the seated and supine positions. Maintaining a fixed position for sufficient time before measurement is important. Translational Relevance Glaucoma patients should focus on the importance of IOP measurements in the clinic occurring after an adequate amount of time in a fixed body position.
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Affiliation(s)
- Shu Tu
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Kang Li
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Dongpeng Hu
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Kaijing Li
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jian Ge
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
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Matsou A, Anastasopoulos E. Investigational drugs targeting prostaglandin receptors for the treatment of glaucoma. Expert Opin Investig Drugs 2018; 27:777-785. [PMID: 30227753 DOI: 10.1080/13543784.2018.1526279] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
INTRODUCTION Prostaglandin F2α analogs were the first prostaglandin agonists introduced for glaucoma treatment. Thanks to their efficacy and favorable tolerability they set a high bar in competition, with a resultant paucity in new hypotensive drug development for many years. However, the scientific community has shown recently a new interest in exploring new options for glaucoma treatment, generating a remarkable incentive in the marketplace for new drugs. AREAS COVERED This article reviews agents targeting prostaglandin receptors that are currently being investigated for glaucoma treatment. We searched published literature for agonists targeting all subtypes of prostaglandin receptors found in ocular tissues. EP and FP receptor agonists are currently in the spotlight of clinical research, while less attention is paid in DP receptor agonists. EXPERT OPINION Prostaglandin analogs, targeting different and combinations of receptor subtypes and compounds that exhibit additivity to commonly prescribed medications seem to be highly promising options. New treatments need to be safe, more effective, superior to existing therapies, tolerable and cost-effective. New generation compounds with multiple mechanisms of action or multiagent formulations are vigorously being investigated and generated in laboratories around the world.
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Affiliation(s)
- Artemis Matsou
- a 2nd Department of Ophthalmology, General Hospital of Papageorgiou, Medical School , Aristotle University of Thessaloniki , Thessaloniki , Greece
| | - Eleftherios Anastasopoulos
- a 2nd Department of Ophthalmology, General Hospital of Papageorgiou, Medical School , Aristotle University of Thessaloniki , Thessaloniki , Greece
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Sharif NA. iDrugs and iDevices Discovery Research: Preclinical Assays, Techniques, and Animal Model Studies for Ocular Hypotensives and Neuroprotectants. J Ocul Pharmacol Ther 2018; 34:7-39. [PMID: 29323613 DOI: 10.1089/jop.2017.0125] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Discovery ophthalmic research is centered around delineating the molecular and cellular basis of ocular diseases and finding and exploiting molecular and genetic pathways associated with them. From such studies it is possible to determine suitable intervention points to address the disease process and hopefully to discover therapeutics to treat them. An investigational new drug (IND) filing for a new small-molecule drug, peptide, antibody, genetic treatment, or a device with global health authorities requires a number of preclinical studies to provide necessary safety and efficacy data. Specific regulatory elements needed for such IND-enabling studies are beyond the scope of this article. However, to enhance the overall data packages for such entities and permit high-quality foundation-building publications for medical affairs, additional research and development studies are always desirable. This review aims to provide examples of some target localization/verification, ocular drug discovery processes, and mechanistic and portfolio-enhancing exploratory investigations for candidate drugs and devices for the treatment of ocular hypertension and glaucomatous optic neuropathy (neurodegeneration of retinal ganglion cells and their axons). Examples of compound screening assays, use of various technologies and techniques, deployment of animal models, and data obtained from such studies are also presented.
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Affiliation(s)
- Najam A Sharif
- 1 Global Alliances & External Research , Santen Incorporated, Emeryville, California.,2 Department of Pharmaceutical Sciences, Texas Southern University , Houston, Texas.,3 Department of Pharmacology and Neuroscience, University of North Texas Health Sciences Center , Fort Worth, Texas
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Woodward DF, Wenthur SL, Rudebush TL, Fan S, Toris CB. Prostanoid Receptor Antagonist Effects on Intraocular Pressure, Supported by Ocular Biodisposition Experiments. J Ocul Pharmacol Ther 2016; 32:606-622. [PMID: 27763812 DOI: 10.1089/jop.2016.0069] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
PURPOSE Since all prostanoid receptors affect intraocular pressure (IOP) and endogenous prostanoids are found in ocular tissues, the pressor effects of prostanoid antagonists were comprehensively evaluated. The absence of effects of most of these antagonists was not entirely anticipated. To ensure no false-negative results, ocular biodisposition studies were conducted. METHODS Monkeys with laser-induced ocular hypertension were used to study antagonist effects on IOP. Ocular biodisposition of each antagonist was assessed in rabbits, with LC/MS/MS analyses of tissue extracts and blood. RESULTS EP1, EP2, EP3, EP4, FP, IP, and TP prostanoid receptor antagonists did not affect IOP, even at a high 1% dose. These studies were followed by ocular biodisposition studies. Striking differences in ocular tissue bioavailability were observed, which were independent of solubility. Only the EP1 antagonist SC-51322 failed to penetrate sufficiently to be bioavailable in the aqueous humor and ciliary body/iris. This obliged testing an alternative EP1 antagonist, namely ONO-8713, to reliably conclude that an EP1 antagonist does not alter IOP. CONCLUSIONS These antagonist studies provided no evidence for individual endogenous prostanoids exerting a meaningful role in regulating IOP. They do reaffirm the critical importance of studying ocular bioavailability for confirming negative data. Large differences among the antagonists in anterior segment and even ocular surface tissue biodisposition were observed in rabbits. It appears from these monkey studies, supported by rabbit ocular bioavailability data, that an absence of drug effect in the eye cannot be adequately substantiated without determination of ocular pharmacokinetics.
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Affiliation(s)
- David F Woodward
- 1 Department of Biological Sciences, Allergan, Inc. , Irvine, California
| | - Stacey L Wenthur
- 2 Department of Ophthalmology and Visual Science, School of Medicine, University of Nebraska Medical Center , Omaha, Nebraska
| | - Tara L Rudebush
- 2 Department of Ophthalmology and Visual Science, School of Medicine, University of Nebraska Medical Center , Omaha, Nebraska
| | - Shan Fan
- 2 Department of Ophthalmology and Visual Science, School of Medicine, University of Nebraska Medical Center , Omaha, Nebraska
| | - Carol B Toris
- 2 Department of Ophthalmology and Visual Science, School of Medicine, University of Nebraska Medical Center , Omaha, Nebraska.,3 Department of Ophthalmology and Visual Science, School of Medicine, Case Western Reserve University , Cleveland, Ohio
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Doucette LP, Walter MA. Prostaglandins in the eye: Function, expression, and roles in glaucoma. Ophthalmic Genet 2016; 38:108-116. [PMID: 27070211 DOI: 10.3109/13816810.2016.1164193] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Prostaglandins are small pro-inflammatory molecules derived from arachidonic acid that play roles in a multitude of biological processes including, but not limited to, inflammation, pain modulation, allergies, and bone formation. Prostaglandin analogues are the front-line medications for the treatment of glaucoma, a condition resulting in blindness due to the death of retinal ganglion cells. These drugs act by lowering intraocular pressure (IOP), a major risk factor for glaucoma. The currently used prostaglandin analogues (latanoprost, bimatoprost, tafluprost, and travoprost) mimic PGF2 and target one of the prostaglandin receptors (FP), though research into harnessing the other receptors using compounds like Sulprostone (EP3 receptor), or Iloprost (IP receptor) are currently ongoing. In this review, we summarize the research into each of the prostaglandin molecules (PGD2, PGE2, PGF2, PGI2, TXA2) and their respective receptors (DP, EP1, 2, 3, 4, FP, IP). We examine the modes of action of each of these receptors, their expression, their role in aqueous humour production and outflow within the eye, as well as their roles as medications for the treatment of glaucoma.
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Affiliation(s)
- Lance P Doucette
- a Department of Medical Genetics, Faculty of Medicine and Dentistry , University of Alberta , Edmonton , Alberta , Canada
| | - Michael A Walter
- a Department of Medical Genetics, Faculty of Medicine and Dentistry , University of Alberta , Edmonton , Alberta , Canada
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Millar JC, Pang IH. Non-continuous measurement of intraocular pressure in laboratory animals. Exp Eye Res 2015; 141:74-90. [PMID: 25933714 DOI: 10.1016/j.exer.2015.04.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 04/21/2015] [Accepted: 04/27/2015] [Indexed: 01/02/2023]
Abstract
Glaucoma is a leading cause of blindness, which is treatable but currently incurable. Numerous animal models therefore have both been and continue to be utilized in the study of numerous aspects of this condition. One important facet associated with the use of such models is the ability to accurately and reproducibly measure (by cannulation) or estimate (by tonometry) intraocular pressure (IOP). At this juncture there are several different approaches to IOP measurement in different experimental animal species, and the list continues to grow. We feel therefore that a review of this subject matter is timely and should prove useful to others who wish to perform similar measurements. The general principles underlying various types of tonometric and non-tonometric techniques for non-continuous determination of IOP are considered. There follows discussion of specific details as to how these techniques are applied to experimental animal species involved in the research of this disease. Specific comments regarding anesthesia, circadian rhythm, and animal handling are also included, especially in the case of rodents. Brief consideration is also given to possible future developments.
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Affiliation(s)
- J Cameron Millar
- North Texas Eye Research Institute (NTERI), University of North Texas Health Science Center (UNTHSC), 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA; Department of Cell Biology and Immunology, University of North Texas Health Science Center (UNTHSC), 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA.
| | - Iok-Hou Pang
- North Texas Eye Research Institute (NTERI), University of North Texas Health Science Center (UNTHSC), 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA; Department of Cell Biology and Immunology, University of North Texas Health Science Center (UNTHSC), 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center (UNTHSC), 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
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9
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Sharif NA, May JA. Potential for serotonergic agents to treat elevated intraocular pressure and glaucoma: focus on 5-HT2receptor agonists. EXPERT REVIEW OF OPHTHALMOLOGY 2014. [DOI: 10.1586/eop.10.69] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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10
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Woodward DF, Jones RL, Narumiya S. International Union of Basic and Clinical Pharmacology. LXXXIII: classification of prostanoid receptors, updating 15 years of progress. Pharmacol Rev 2011; 63:471-538. [PMID: 21752876 DOI: 10.1124/pr.110.003517] [Citation(s) in RCA: 321] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
It is now more than 15 years since the molecular structures of the major prostanoid receptors were elucidated. Since then, substantial progress has been achieved with respect to distribution and function, signal transduction mechanisms, and the design of agonists and antagonists (http://www.iuphar-db.org/DATABASE/FamilyIntroductionForward?familyId=58). This review systematically details these advances. More recent developments in prostanoid receptor research are included. The DP(2) receptor, also termed CRTH2, has little structural resemblance to DP(1) and other receptors described in the original prostanoid receptor classification. DP(2) receptors are more closely related to chemoattractant receptors. Prostanoid receptors have also been found to heterodimerize with other prostanoid receptor subtypes and nonprostanoids. This may extend signal transduction pathways and create new ligand recognition sites: prostacyclin/thromboxane A(2) heterodimeric receptors for 8-epi-prostaglandin E(2), wild-type/alternative (alt4) heterodimers for the prostaglandin FP receptor for bimatoprost and the prostamides. It is anticipated that the 15 years of research progress described herein will lead to novel therapeutic entities.
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Affiliation(s)
- D F Woodward
- Dept. of Biological Sciences RD3-2B, Allergan, Inc., 2525 Dupont Dr., Irvine, CA 92612, USA.
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Barraza RA, Rasmussen CA, Loewen N, Cameron JD, Gabelt BT, Teo WL, Kaufman PL, Poeschla EM. Prolonged transgene expression with lentiviral vectors in the aqueous humor outflow pathway of nonhuman primates. Hum Gene Ther 2009; 20:191-200. [PMID: 19301472 DOI: 10.1089/hum.2008.086] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
We injected lentiviral vectors into the eyes of live nonhuman primates to assess potential for glaucoma gene therapy. Anterior chambers of five cynomolgus monkeys were injected with green fluorescent protein (GFP)-encoding feline immunodeficiency viral vectors. The monkeys were monitored for in vivo transgene expression and clinical parameters. Their eyes were harvested 2-15 months postinjection for tissue analyses. All seven eyes injected with 1.0-2.0 x 10(8) transducing units (TU) showed substantial GFP fluorescence in the trabecular meshwork (TM), which was observable even by goniophotographic monitoring for up to 15 months. Only the lowest dose (0.03 x 10(8) TU) failed to result in TM fluorescence detectable in vivo, and five of the eight vector-injected eyes continued to display substantial GFP expression when enucleated eyes were examined at 2, 7, or 15 months postinjection. Some transduced cells were also detected in the iris and ciliary body. Mild, transient postinjection inflammatory responses exceeding that induced by a control saline injection were observed, but vectors did not raise intraocular pressure and were well tolerated. The results demonstrate the first lentiviral vector transduction of the nonhuman primate aqueous humor outflow pathway and support application of the system to human glaucoma gene therapy.
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Affiliation(s)
- Román A Barraza
- Department of Molecular Medicine, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA
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Poeschla EM, Barraza RA, Rasmussen C, Loewen N, Cameron JD, Gabelt BT, Teo W, Kaufman PL. Prolonged transgene expression with lentiviral vectors in the aqueous humor outflow pathway of non-human primates. Hum Gene Ther 2008. [DOI: 10.1089/hgt.2008.086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Toris CB, Gabelt BT, Kaufman PL. Update on the mechanism of action of topical prostaglandins for intraocular pressure reduction. Surv Ophthalmol 2008; 53 Suppl1:S107-20. [PMID: 19038618 PMCID: PMC2727743 DOI: 10.1016/j.survophthal.2008.08.010] [Citation(s) in RCA: 214] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
A decade has passed since the first topical prostaglandin analog was prescribed to reduce intraocular pressure (IOP) for the treatment of glaucoma. Now four prostaglandin analogs are available for clinical use around the world and more are in development. The three most efficacious of these drugs are latanoprost, travoprost, and bimatoprost, and their effects on IOP and aqueous humor dynamics are similar. A consistent finding is a substantial increase in uveoscleral outflow and a less consistent finding is an increase in trabecular outflow facility. Aqueous flow appears to be slightly stimulated as well. Prostaglandin receptors and their associated mRNAs have been located in the trabecular meshwork, ciliary muscle, and sclera, providing evidence that endogenous prostaglandins have a functional role in aqueous humor drainage. Earlier evidence found that topical PG analogs release endogenous prostaglandins. One well-studied mechanism for the enhancement of outflow by prostaglandins is the regulation of matrix metalloproteinases and remodeling of extracellular matrix. Other proposed mechanisms include widening of the connective tissue-filled spaces and changes in the shape of cells. All of these mechanisms alter the permeability of tissues of the outflow pathways leading to changes in outflow resistance and/or outflow rates. This review summarizes recent (since 2000) animal and clinical studies of the effects of topical prostaglandin analogs on aqueous humor dynamics and recent cellular and molecular studies designed to clarify the outflow effects.
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Affiliation(s)
- Carol B Toris
- Department of Ophthalmology, University of Nebraska Medical Center, Omaha, Nebraska 68198-5840, USA.
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Sharif NA, McLaughlin MA, Kelly CR, Katoli P, Drace C, Husain S, Crosson C, Toris C, Zhan GL, Camras C. Cabergoline: Pharmacology, ocular hypotensive studies in multiple species, and aqueous humor dynamic modulation in the Cynomolgus monkey eyes. Exp Eye Res 2008; 88:386-97. [PMID: 18992242 DOI: 10.1016/j.exer.2008.10.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Revised: 09/19/2008] [Accepted: 10/01/2008] [Indexed: 12/11/2022]
Abstract
The aims of the current studies were to determine the in vitro and in vivo ocular and non-ocular pharmacological properties of cabergoline using well documented receptor binding, cell-based functional assays, and in vivo models. Cabergoline bound to native and/or human cloned serotonin-2A/B/C (5HT(2A/B/C)), 5HT(1A), 5HT(7), alpha(2B), and dopamine-2/3 (D(2/3)) receptor subtypes with nanomolar affinity. Cabergoline was an agonist at human recombinant 5HT(2), 5HT(1A) and D(2/3) receptors but an antagonist at 5HT(7) and alpha(2) receptors. In primary human ciliary muscle (h-CM) and trabecular meshwork (h-TM) cells, cabergoline stimulated phosphoinositide (PI) hydrolysis (EC(50)=19+/-7 nM in TM; 76 nM in h-CM) and intracellular Ca(2+) ([Ca(2+)](i)) mobilization (EC(50)=570+/-83 nM in h-TM; EC(50)=900+/-320 nM in h-CM). Cabergoline-induced [Ca(2+)](i) mobilization in h-TM and h-CM cells was potently antagonized by a 5HT(2A)-selective antagonist (M-100907, K(i)=0.29-0.53 nM). Cabergoline also stimulated [Ca(2+)](i) mobilization more potently via human cloned 5HT(2A) (EC(50)=63.4+/-10.3 nM) than via 5HT(2B) and 5HT(2C) receptors. In h-CM cells, cabergoline (1 microM) stimulated production of pro-matrix metalloproteinases-1 and -3 and synergized with forskolin to enhance cAMP production. Cabergoline (1 microM) perfused through anterior segments of porcine eyes caused a significant (27%) increase in outflow facility. Topically administered cabergoline (300-500 microg) in Dutch-belted rabbit eyes yielded 4.5 microMM and 1.97 microM levels in the aqueous humor 30 min and 90 min post-dose but failed to modulate intraocular pressure (IOP). However, cabergoline was an efficacious IOP-lowering agent in normotensive Brown Norway rats (25% IOP decrease with 6 microg at 4h post-dose) and in conscious ocular hypertensive cynomolgus monkeys (peak reduction of 30.6+/-3.6% with 50 microg at 3h post-dose; 30.4+/-4.5% with 500 microg at 7h post-dose). In ketamine-sedated monkeys, IOP was significantly lowered at 2.5h after the second topical ocular dose (300 microg) of cabergoline by 23% (p<0.02) and 35% (p<0.004) in normotensive and ocular hypertensive eyes, respectively. In normotensive eyes, cabergoline increased uveoscleral outflow (0.69+/-0.7 microL/min-1.61+/-0.97 microL/min, n=13; p<0.01). However, only seven of the eleven ocular hypertensive monkeys showed significantly increased uveoscleral outflow. These data indicate that cabergoline's most prominent agonist activity involves activation of 5HT(2), 5HT(1A), and D(2/3) receptors. Since 5HT(1A) agonists, 5HT(7) antagonists, and alpha(2) antagonists do not lower IOP in conscious ocular hypertensive monkeys, the 5HT(2) and dopaminergic agonist activities of cabergoline probably mediated the IOP reduction observed with this compound in this species.
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Affiliation(s)
- Najam A Sharif
- Discovery Ophthalmology Research, Alcon Research Ltd, Fort worth, TX, USA.
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