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Denzer L, Muranyi W, Schroten H, Schwerk C. The role of PLVAP in endothelial cells. Cell Tissue Res 2023; 392:393-412. [PMID: 36781482 PMCID: PMC10172233 DOI: 10.1007/s00441-023-03741-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 01/18/2023] [Indexed: 02/15/2023]
Abstract
Endothelial cells play a major part in the regulation of vascular permeability and angiogenesis. According to their duty to fit the needs of the underlying tissue, endothelial cells developed different subtypes with specific endothelial microdomains as caveolae, fenestrae and transendothelial channels which regulate nutrient exchange, leukocyte migration, and permeability. These microdomains can exhibit diaphragms that are formed by the endothelial cell-specific protein plasmalemma vesicle-associated protein (PLVAP), the only known protein component of these diaphragms. Several studies displayed an involvement of PLVAP in diseases as cancer, traumatic spinal cord injury, acute ischemic brain disease, transplant glomerulopathy, Norrie disease and diabetic retinopathy. Besides an upregulation of PLVAP expression within these diseases, pro-angiogenic or pro-inflammatory responses were observed. On the other hand, loss of PLVAP in knockout mice leads to premature mortality due to disrupted homeostasis. Generally, PLVAP is considered as a major factor influencing the permeability of endothelial cells and, finally, to be involved in the regulation of vascular permeability. Following these observations, PLVAP is debated as a novel therapeutic target with respect to the different vascular beds and tissues. In this review, we highlight the structure and functions of PLVAP in different endothelial types in health and disease.
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Affiliation(s)
- Lea Denzer
- Department of Pediatrics, Pediatric Infectious Diseases, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Walter Muranyi
- Department of Pediatrics, Pediatric Infectious Diseases, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Horst Schroten
- Department of Pediatrics, Pediatric Infectious Diseases, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Christian Schwerk
- Department of Pediatrics, Pediatric Infectious Diseases, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
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Bosma EK, van Noorden CJF, Schlingemann RO, Klaassen I. The role of plasmalemma vesicle-associated protein in pathological breakdown of blood-brain and blood-retinal barriers: potential novel therapeutic target for cerebral edema and diabetic macular edema. Fluids Barriers CNS 2018; 15:24. [PMID: 30231925 PMCID: PMC6146740 DOI: 10.1186/s12987-018-0109-2] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 08/10/2018] [Indexed: 12/14/2022] Open
Abstract
Breakdown of the blood–brain barrier (BBB) or inner blood–retinal barrier (BRB), induced by pathologically elevated levels of vascular endothelial growth factor (VEGF) or other mediators, can lead to vasogenic edema and significant clinical problems such as neuronal morbidity and mortality, or vision loss. Restoration of the barrier function with corticosteroids in the brain, or by blocking VEGF in the eye are currently the predominant treatment options for brain edema and diabetic macular edema, respectively. However, corticosteroids have side effects, and VEGF has important neuroprotective, vascular protective and wound healing functions, implying that long-term anti-VEGF therapy may also induce adverse effects. We postulate that targeting downstream effector proteins of VEGF and other mediators that are directly involved in the regulation of BBB and BRB integrity provide more attractive and safer treatment options for vasogenic cerebral edema and diabetic macular edema. The endothelial cell-specific protein plasmalemma vesicle-associated protein (PLVAP), a protein associated with trans-endothelial transport, emerges as candidate for this approach. PLVAP is expressed in a subset of endothelial cells throughout the body where it forms the diaphragms of caveolae, fenestrae and trans-endothelial channels. However, PLVAP expression in brain and eye barrier endothelia only occurs in pathological conditions associated with a compromised barrier function such as cancer, ischemic stroke and diabetic retinopathy. Here, we discuss the current understanding of PLVAP as a structural component of endothelial cells and regulator of vascular permeability in health and central nervous system disease. Besides providing a perspective on PLVAP identification, structure and function, and the regulatory processes involved, we also explore its potential as a novel therapeutic target for vasogenic cerebral edema and retinal macular edema.
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Affiliation(s)
- Esmeralda K Bosma
- Ocular Angiogenesis Group, Departments of Ophthalmology and Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, Amsterdam, The Netherlands
| | - Cornelis J F van Noorden
- Ocular Angiogenesis Group, Departments of Ophthalmology and Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, Amsterdam, The Netherlands.,Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Ljubljana, Slovenia
| | - Reinier O Schlingemann
- Ocular Angiogenesis Group, Departments of Ophthalmology and Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, Amsterdam, The Netherlands.,Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
| | - Ingeborg Klaassen
- Ocular Angiogenesis Group, Departments of Ophthalmology and Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, Amsterdam, The Netherlands. .,Ocular Angiogenesis Group, Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Meibergdreef 15, Room L3-154, 1105 AZ, Amsterdam, The Netherlands.
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Kubo Y, Akanuma SI, Hosoya KI. Recent advances in drug and nutrient transport across the blood-retinal barrier. Expert Opin Drug Metab Toxicol 2018; 14:513-531. [PMID: 29719158 DOI: 10.1080/17425255.2018.1472764] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
INTRODUCTION The blood-retinal barrier (BRB) is the barrier separating the blood and neural retina, and transport systems for low-weight molecules at the BRB are expected to be useful for developing drugs for the treatment of ocular neural disorders and maintaining a healthy retina. Areas covered: This review discusses blood-to-retina and retina-to-blood transport of drugs and nutrients at the BRB. In particular, P-gp (ABCB1/MDR1) has low impact on the transport of cationic drugs at the BRB, suggesting a significant role of novel organic cation transporters in influx and efflux transport of lipophilic cationic drugs between blood and the retina. The transport of pravastatin at the BRB involves transporters including organic anion transporting polypeptide 1a4 (Oatp1a4). Recent studies have shown the involvement of solute carrier transporters in the blood-to-retina transport of nutrients including riboflavin, L-ornithine, β-alanine, and L-histidine, implying that dipeptide transport at the BRB is minimal. Expert opinion: Novel organic cation transport systems and the elimination-dominant transport of pravastatin at the BRB are expected to be useful in systemic drug delivery to the neural retina without CNS side effects. The mechanism of nutrient transport at the BRB is expected to provide a new strategy for delivery of nutrient-mimetic drugs.
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Affiliation(s)
- Yoshiyuki Kubo
- a Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences , University of Toyama , Toyama , Japan
| | - Shin-Ichi Akanuma
- a Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences , University of Toyama , Toyama , Japan
| | - Ken-Ichi Hosoya
- a Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences , University of Toyama , Toyama , Japan
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Vellonen KS, Hellinen L, Mannermaa E, Ruponen M, Urtti A, Kidron H. Expression, activity and pharmacokinetic impact of ocular transporters. Adv Drug Deliv Rev 2018; 126:3-22. [PMID: 29248478 DOI: 10.1016/j.addr.2017.12.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 10/24/2017] [Accepted: 12/13/2017] [Indexed: 12/13/2022]
Abstract
The eye is protected by several tissues that limit the permeability and entry of potentially harmful substances, but also hamper the delivery of drugs in the treatment of ocular diseases. Active transport across the ocular barriers may affect drug distribution, but the impact of drug transporters on ocular drug delivery is not well known. We have collected and critically reviewed the literature for ocular expression and activity of known drug transporters. The review concentrates on drug transporters that have been functionally characterized in ocular tissues or primary cells and on transporters for which there is available expression data at the protein level. Species differences are highlighted, since these may explain observed inconsistencies in the influence of specific transporters on drug disposition. There is variable evidence about the pharmacokinetic role of transporters in ocular tissues. The strongest evidence for the role of active transport is available for the blood-retinal barrier. We explored the role of active transport in the cornea and blood retinal barrier with pharmacokinetic simulations. The simulations show that the active transport is important only in the case of specific parameter combinations.
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Barar J, Aghanejad A, Fathi M, Omidi Y. Advanced drug delivery and targeting technologies for the ocular diseases. BIOIMPACTS : BI 2016; 6:49-67. [PMID: 27340624 PMCID: PMC4916551 DOI: 10.15171/bi.2016.07] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 02/13/2016] [Accepted: 03/18/2016] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Ocular targeted therapy has enormously been advanced by implementation of new methods of drug delivery and targeting using implantable drug delivery systems (DDSs) or devices (DDDs), stimuli-responsive advanced biomaterials, multimodal nanomedicines, cell therapy modalities and medical bioMEMs. These technologies tackle several ocular diseases such as inflammation-based diseases (e.g., scleritis, keratitis, uveitis, iritis, conjunctivitis, chorioretinitis, choroiditis, retinitis, retinochoroiditis), ocular hypertension and neuropathy, age-related macular degeneration and mucopolysaccharidosis (MPS) due to accumulation of glycosaminoglycans (GAGs). Such therapies appear to provide ultimate treatments, even though much more effective, yet biocompatible, noninvasive therapies are needed to control some disabling ocular diseases/disorders. METHODS In the current study, we have reviewed and discussed recent advancements on ocular targeted therapies. RESULTS On the ground that the pharmacokinetic and pharmacodynamic analyses of ophthalmic drugs need special techniques, most of ocular DDSs/devices developments have been designed to localized therapy within the eye. Application of advanced DDSs such as Subconjunctival insert/implants (e.g., latanoprost implant, Gamunex-C), episcleral implant (e.g., LX201), cationic emulsions (e.g., Cationorm™, Vekacia™, Cyclokat™), intac/punctal plug DDSs (latanoprost punctal plug delivery system, L-PPDS), and intravitreal implants (I-vitaion™, NT-501, NT- 503, MicroPump, Thethadur, IB-20089 Verisome™, Cortiject, DE-102, Retisert™, Iluvein™ and Ozurdex™) have significantly improved the treatment of ocular diseases. However, most of these DDSs/devices are applied invasively and even need surgical procedures. Of these, use of de novo technologies such as advanced stimuli-responsive nanomaterials, multimodal nanosystems (NSs)/nanoconjugates (NCs), biomacromolecualr scaffolds, and bioengineered cell therapies need to be further advanced to get better compliance and higher clinical impacts. CONCLUSION Despite mankind successful battle on ocular diseases, our challenge will continue to battle the ocular disease that happen with aging. Yet, we need to understand the molecular aspects of eye diseases in a holistic way and develop ultimate treatment protocols preferably as non-invasive systems.
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Affiliation(s)
| | | | | | - Yadollah Omidi
- Research Centre for Pharmaceutical Nanotechnology, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
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Lee J, Pelis RM. Drug Transport by the Blood-Aqueous Humor Barrier of the Eye. Drug Metab Dispos 2016; 44:1675-81. [DOI: 10.1124/dmd.116.069369] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 02/18/2016] [Indexed: 11/22/2022] Open
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Ikeda N, Ikeda T, Kohno T. Traumatic myopia secondary to ciliary spasm after blunt eye trauma and reconsideration of its pathogenesis. Graefes Arch Clin Exp Ophthalmol 2016; 254:1411-7. [PMID: 26860527 DOI: 10.1007/s00417-016-3282-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 01/19/2016] [Accepted: 01/25/2016] [Indexed: 10/22/2022] Open
Abstract
PURPOSE To reconsider the pathogenesis of traumatic myopia by describing two cases and literature review. METHODS Refraction was measured, A-scan ultrasonography was performed, and ultrasound biomicroscopy (UBM) was used to observe the ciliary body in the acute and recovery stages. RESULTS The first patient had a myopic shift of -6.12 diopters (D) on the initial examination (day 2) compared with the recovered stage. UBM showed ciliochoroidal effusion in one half of the circumference and severe edema in three eighths of the ciliary body, which led to an anterior rotation of the ciliary body. Immediately after the cycloplegia, the myopic shift decreased by -3.9 D. On day 11, the refraction was -0.63 D, and the UBM findings were normalized. The second patient had a myopic shift of -4.38 D on the first examination compared with the recovered stage. UBM showed an annular ciliochoroidal effusion leading to anterior rotation of the ciliary body. Immediately after the cycloplegia, there was a decrease of -2.75 D. Biometric measurements showed an increased anterior chamber depth and a decreased thickness of the lens. On day 16, the refraction was -1.0 D, and the UBM findings were normalized. In both cases, biometric measurements in the acute phase suggested a anterior chamber shallowing, a thickening of the lens, and an anterior shift of the lens-iris diaphragm CONCLUSIONS Cycloplegia decreased the myopic shift by more than 60 %. These findings indicate a significant contribution of ciliary spasm combined with ciliochoroidal effusion, anterior shift of the lens-iris diaphragm, and thickening of the lens.
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Affiliation(s)
- Naohiro Ikeda
- Department of Ophthalmology, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya-shi, Hyogo, 663-8501, Japan.
| | - Tomohiro Ikeda
- Department of Ophthalmology, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya-shi, Hyogo, 663-8501, Japan
| | - Takeya Kohno
- Department of Ophthalmology and Visual Science, Graduate School of Medicine, Osaka City University, 1-4-3 Asahi-machi, Abeno-ku, Osaka, 545-8585, Japan
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Vaishya RD, Khurana V, Patel S, Mitra AK. Controlled ocular drug delivery with nanomicelles. WILEY INTERDISCIPLINARY REVIEWS. NANOMEDICINE AND NANOBIOTECHNOLOGY 2014; 6:422-37. [PMID: 24888969 PMCID: PMC4155159 DOI: 10.1002/wnan.1272] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Revised: 03/27/2014] [Accepted: 04/06/2014] [Indexed: 01/22/2023]
Abstract
Many vision threatening ocular diseases such as age-related macular degeneration (AMD), diabetic retinopathy, glaucoma, and proliferative vitreoretinopathy may result in blindness. Ocular drug delivery specifically to the intraocular tissues remains a challenging task due to the presence of various physiological barriers. Nonetheless, recent advancements in the field of nanomicelle-based novel drug delivery system could fulfil these unmet needs. Nanomicelles consists of amphiphilic molecules that self-assemble in aqueous media to form organized supramolecular structures. Micelles can be prepared in various sizes (10-1000 nm) and shapes depending on the molecular weights of the core and corona forming blocks. Nanomicelles have been an attractive carrier for their potential to solubilize hydrophobic molecules in aqueous solution. In addition, small size in nanometer range and highly modifiable surface properties have been reported to be advantageous in ocular drug delivery. In this review, various factors influencing rationale design of nanomicelles formulation and disposition are discussed along with case studies. Despite the progress in the field, influence of various properties of nanomicelles such as size, shape, surface charge, rigidity of structure on ocular disposition need to be studied in further details to develop an efficient nanocarrier system.
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Affiliation(s)
- Ravi D. Vaishya
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 2464 Charlotte Street, Kansas City, Missouri 64108-2718, U.S.A
| | - Varun Khurana
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 2464 Charlotte Street, Kansas City, Missouri 64108-2718, U.S.A. & INSYS Therapeutics Inc, 444 South Ellis Road, Chandler, AZ, 85224, U.S.A
| | - Sulabh Patel
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 2464 Charlotte Street, Kansas City, Missouri 64108-2718, U.S.A
| | - Ashim K. Mitra
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 2464 Charlotte Street, Kansas City, Missouri 64108-2718, U.S.A
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Abstract
The eye is a highly protected organ, and designing an effective therapy is often considered a challenging task. The anatomical and physiological barriers result in low ocular bioavailability of drugs. Due to these constraints, less than 5% of the administered dose is absorbed from the conventional ophthalmic dosage forms. Further, physicochemical properties such as lipophilicity, molecular weight and charge modulate the permeability of drug molecules. Vision-threatening diseases such as glaucoma, diabetic macular edema, cataract, wet and dry age-related macular degeneration, proliferative vitreoretinopathy, uveitis, and cytomegalovirus retinitis alter the pathophysiological and molecular mechanisms. Understanding these mechanisms may result in the development of novel treatment modalities. Recently, transporter/receptor targeted prodrug approach has generated significant interest in ocular drug delivery. These transporters and receptors are involved in the transport of essential nutrients, vitamins, and xenobiotics across biological membranes. Several influx transporters (peptides, amino acids, glucose, lactate and nucleosides/nucleobases) and receptors (folate and biotin) have been identified on conjunctiva, cornea, and retina. Structural and functional delineation of these transporters will enable more drugs targeting the posterior segment to be successfully delivered topically. Prodrug derivatization targeting transporters and receptors expressed on ocular tissues has been the subject of intense research. Several prodrugs have been designed to target these transporters and enhance the absorption of poorly permeating parent drug. Moreover, this approach might be used in gene delivery to modify cellular function and membrane receptors. This review provides comprehensive information on ocular drug delivery, with special emphasis on the use of transporters and receptors to improve drug bioavailability.
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Toda R, Kawazu K, Oyabu M, Miyazaki T, Kiuchi Y. Comparison of Drug Permeabilities Across the Blood–Retinal Barrier, Blood–Aqueous Humor Barrier, and Blood–Brain Barrier. J Pharm Sci 2011; 100:3904-11. [DOI: 10.1002/jps.22610] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Revised: 04/11/2011] [Accepted: 04/19/2011] [Indexed: 11/08/2022]
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Abstract
Targeted nanoparticles have the potential to improve drug delivery efficiencies by more than two orders of magnitude, from the ~ 0.1% which is common today. Most pharmacologically agents on the market today are small drug molecules, which diffuse across the body’s blood-tissue barriers and distribute not only into the lesion, but into almost all organs. Drug actions in the non-lesion organs are an inescapable part of the drug delivery principle, causing “side-effects” which limit the maximally tolerable doses and result in inadequate therapy of many lesions. Nanoparticles only cross barriers by design, so side-effects are not built into their mode of operation. Delivery rates of almost 90% have been reported. This review examines the significance of these statements and checks how far they need qualification. What type of targeting is required? Is a single targeting sufficient? What new types of clinical challenge, such as immunogenicity, might attend the use of targeted nanoparticles?
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Tomi M, Hosoya KI. The role of blood–ocular barrier transporters in retinal drug disposition: an overview. Expert Opin Drug Metab Toxicol 2010; 6:1111-24. [DOI: 10.1517/17425255.2010.486401] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Klaassen I, Hughes JM, Vogels IM, Schalkwijk CG, Van Noorden CJ, Schlingemann RO. Altered expression of genes related to blood–retina barrier disruption in streptozotocin-induced diabetes. Exp Eye Res 2009; 89:4-15. [DOI: 10.1016/j.exer.2009.01.006] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Revised: 10/31/2008] [Accepted: 01/12/2009] [Indexed: 11/28/2022]
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Senthilkumari S, Velpandian T, Biswas NR, Sonali N, Ghose S. Evaluation of the impact of P-glycoprotein (P-gp) drug efflux transporter blockade on the systemic and ocular disposition of P-gp substrate. J Ocul Pharmacol Ther 2008; 24:290-300. [PMID: 18476799 DOI: 10.1089/jop.2007.0063] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
PURPOSE The impact of P-glycoprotein (P-gp) blockade on the intravenous (i.v.) pharmacokinetics of rhodamine-123 (Rho-123), and the subsequent effect on its disposition in ocular and nonocular tissues, was studied by using rabbits. METHODS Three (3) control rabbits received only an i.v. bolus dose of Rho-123 (1.52 mg/kg). Three (3) blocker-pretreated rabbits received an i.v. dose of GF120918 (3.5 mg/kg) 30 min before the i.v. bolus of Rho-123. The plasma concentration of Rho-123 at different time points was subjected to a pharmacokinetic compartmental analysis, using WinNonlin (Scientific Consultants, Lexington, KY). For tissue-distribution study, a drug treatment similar to the i.v. kinetic study was followed by having 5 rabbits in each group. The animals were sacrificed at 30 min with an excess of anesthesia. Plasma and tissues samples were analyzed by using a validated high-performance liquid chromatographic IV method with a fluorescent detector. RESULTS The method validated was sensitive enough to estimate Rho-123 up to 1.94 ng/mL in plasma. I.v. Rho-123 data fitted well into the three-compartment model, and P-gp blocker treatment changed it into a two-compartment model. The P-gp blockade significantly increased the mean tissue concentrations in the lungs and spleen, whereas the rise in mean tissue levels in the heart, liver, and kidney and in all ocular tissues were found to be statistically insignificant. CONCLUSIONS Increasing the ocular concentration of systemically given drugs may not be possible with the degree of P-gp blockade achieved when using GF120918 at the studied concentration after an i.v. administration.
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Affiliation(s)
- Srinivasan Senthilkumari
- Department of Ocular Pharmacology and Pharmacy, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
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Barar J, Javadzadeh AR, Omidi Y. Ocular novel drug delivery: impacts of membranes and barriers. Expert Opin Drug Deliv 2008; 5:567-81. [PMID: 18491982 DOI: 10.1517/17425247.5.5.567] [Citation(s) in RCA: 184] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
BACKGROUND Ocular drug delivery is an extremely challenging area due to its restrictive barrier functionalities. OBJECTIVE Drug transport via corneal/non-corneal routes involves several intricate biological processes such as drug penetration across the ocular barriers and transfer to the anterior or posterior chambers, thus the influence of these processes on the pharmacotherapy of the eye should be fully addressed. METHODS To pursue the impacts of such impediments in novel drug therapy, recent publications were reviewed regarding advanced strategies such as nanomedicines. CONCLUSION The ocular barriers are highly specialized and selectively control the inward/outward traverse of compounds, hence a better understanding of these biological obstacles would provide a platform to advance ophthalmic drug therapy towards specified delivery/targeting with minimal adverse consequences.
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Affiliation(s)
- Jaleh Barar
- Cellular & Molecular Pharmaceutics, Tabriz University of Medical Sciences, Research Centre for Pharmaceutical Nanotechnology, Faculty of Pharmacy, Tabriz, Iran
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Dey S. Single nucleotide polymorphisms in human P-glycoprotein: its impact on drug delivery and disposition. Expert Opin Drug Deliv 2006; 3:23-35. [PMID: 16370938 DOI: 10.1517/17425247.3.1.23] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Drug efflux pumps belong to a large family of ATP-binding cassette transporter proteins. These pumps bind their substrate and export it through the membrane using energy derived from ATP hydrolysis. P-glycoprotein, the main efflux pump in this family, is expressed not only in tumour cells but also in normal tissues with excretory function (liver, kidney and the intestine). It has a broad specificity of substrates and plays an important role in drug delivery and disposition. Recently, genetic screening of P-glycoprotein has yielded multiple single nucleotide polymorphisms, which seem to alter transporter function and expression. This review discusses the various polymorphisms of this gene and its impact on drug disposition and diseases.
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Affiliation(s)
- Surajit Dey
- College of Pharmacy, University of Southern Nevada, 11 Sunset Way, Henderson, NV 89014, USA.
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Phung TL, Hochman M, Mihm MC. Current Knowledge of the Pathogenesis of Infantile Hemangiomas. ACTA ACUST UNITED AC 2005; 7:319-21. [PMID: 16172341 DOI: 10.1001/archfaci.7.5.319] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Infantile hemangiomas are the most common benign tumor of infancy, occurring shortly after birth in 5% to 10% of white infants. Hemangiomas occur in infants of all races but are most common in those who are white. These lesions are preponderant in females compared with males at rates of 3:1 to 5:1. Many hemangiomas are discrete, well-circumscribed masses present in the head and neck. Some hemangiomas are segmental and diffuse, often involving large areas of the extremities or the head and neck. Chorionic villus sampling at 9 to 12 weeks of gestation has been associated with a 21% increased incidence of hemangiomas in infants. Most hemangiomas occur sporadically without a hereditary component. However, in a few families, hemangiomas segregate as a highly penetrant, autosomal dominant trait. Gene linkage studies of familial infantile hemangiomas show evidence of linkage to chromosome 5q31-33.
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Affiliation(s)
- Thuy L Phung
- Department of Pathology, Beth Israel Deaconess Medical Center, Boston, Mass 02215, USA.
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Hornof M, Toropainen E, Urtti A. Cell culture models of the ocular barriers. Eur J Pharm Biopharm 2005; 60:207-25. [PMID: 15939234 DOI: 10.1016/j.ejpb.2005.01.009] [Citation(s) in RCA: 193] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2004] [Revised: 12/28/2004] [Accepted: 01/10/2005] [Indexed: 12/21/2022]
Abstract
The presence of tight barriers, which regulate the environment of ocular tissues in the anterior and posterior part of the eye, is essential for normal visual function. The development of strategies to overcome these barriers for the targeted ocular delivery of drugs, e.g. to the retina, remains a major challenge. During the last years numerous cell culture models of the ocular barriers (cornea, conjunctiva, blood-retinal barrier) have been established. They are considered to be promising tools for studying the drug transport into ocular tissues, and for numerous other purposes, such as the investigation of pathological ocular conditions, and the toxicological screening of compounds as alternative to in vivo toxicity tests. The further development of these in vitro models will require more detailed investigations of the barrier properties of both the cell culture models and the in vivo ocular barriers. It is the aim of this review to describe the current status in the development of cell culture models of the ocular barriers, and to discuss the applicability of these models in pharmaceutical research.
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Affiliation(s)
- Margit Hornof
- Department of Pharmaceutics, University of Kuopio, Kuopio, Finland
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Dey S, Gunda S, Mitra AK. Pharmacokinetics of erythromycin in rabbit corneas after single-dose infusion: role of P-glycoprotein as a barrier to in vivo ocular drug absorption. J Pharmacol Exp Ther 2004; 311:246-55. [PMID: 15175422 DOI: 10.1124/jpet.104.069583] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Efflux pump like P-glycoprotein (P-gp) is known to be a major barrier to drug delivery. Functional P-glycoprotein has been recently identified in cornea and corneal cell lines. Thus, it is probable that P-glycoprotein may restrict in vivo ocular drug absorption, resulting in low ocular bioavailability. Experiments were designed using New Zealand albino (New Zealand White) rabbits to assess inhibitors of P-gp efflux to increase drug absorption. Anesthetized rabbits were given constant topical infusions of [(14)C]erythromycin in the presence and absence of inhibitors. Testosterone, verapamil, quinidine, and cyclosporine A were selected as P-gp inhibitors. Transport experiments were conducted in Madin-Darby canine kidney cells transfected with the human mdr1 gene (MDCK-MDR1). Erythromycin exhibited significant efflux out of MDCK-MDR1 cells, suggesting that erythromycin is a good substrate for P-gp. Ocular pharmacokinetic studies were conducted using a topical single-dose infusion method. Maximum inhibition of P-gp mediated efflux was observed with 500 microM testosterone. Area under the curve (AUC)(0- infinity ) of erythromycin with 500 microM testosterone was almost 4 times higher than AUC(0- infinity ) without any inhibitor. Rate of elimination (k(10)) for erythromycin and those with inhibitors was found to be similar (141 +/- 23 min), suggesting that elimination pathways were not altered. All the inhibitors were found to be nontoxic. Verapamil also inhibited the efflux pump with moderate change in AUC(0- infinity ) and C(max) compared with control. Thus, P-gp is found to be active in vivo, and it restricts topical erythromycin absorption across the cornea, which can be inhibited by known P-gp inhibitors. Therefore, ocular bioavailability of P-gp substrates can be significantly enhanced by proper selection of P-gp inhibitors.
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Affiliation(s)
- Surajit Dey
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 5005 Rockhill Rd., Kansas City, MO 64110-2499, USA
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Dey S, Anand BS, Patel J, Mitra AK. Transporters/receptors in the anterior chamber: pathways to explore ocular drug delivery strategies. Expert Opin Biol Ther 2003; 3:23-44. [PMID: 12718729 DOI: 10.1517/14712598.3.1.23] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Membrane transporters/receptors are involved in drug transport processes and play a key role in intestinal absorption, tissue distribution and elimination. Drug targeting to specific transporters and receptors using carrier-mediated absorption has immense clinical significance. Ocular drug delivery is a challenging task since it involves drug transport across various barriers in the eye. Specialised transport processes exist at these barriers, which control the entry of drugs and xenobiotics. Ocular drug therapy involving topical or systemic administration of drugs has various limitations. Transport processes in the eye have been targeted in an effort to increase ocular bioavailability of drugs following topical instillation. This review discusses various transport processes in the eye and drug delivery strategies utilising these transporters/receptors.
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Affiliation(s)
- Surajit Dey
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 5005 Rockhill Road, Kansas City, Missouri 64110-2499, USA
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Abstract
Juvenile hemangiomas are common, benign vascular tumors of infancy. These lesions enlarge rapidly through cellular hyperplasia during the first year of life and then involute over several years. Distinctive histopathologic features of hemangiomas diminish during this evolution, and differentiation from vascular malformations becomes increasingly difficult. This distinction has important therapeutic implications, as juvenile hemangiomas differ from malformations in natural history and in potential for recurrence. We report here that high endothelial immunoreactivity for the erythrocyte-type glucose transporter protein GLUT1 is a specific feature of juvenile hemangiomas during all phases of these lesions. In a retrospective study, we found intense endothelial GLUT1 immunoreactivity, involving more than 50% of lesional microvessels, in 97% (139 of 143) of juvenile hemangiomas from patients aged 1 month to 11 years. No endothelial GLUT1 immunoreactivity was found in any of 66 vascular malformations (17 arteriovenous, 33 venous, 11 lymphatic, and 5 port-wine) from patients aged 5 days to 75 years, or in any of 20 pyogenic granulomas or 7 granulation tissue specimens. Abundant Ki-67 positivity in these latter lesions established that GLUT1 expression does not simply reflect mitotically active endothelium. Focal GLUT1 immunoreactivity was found in 3 of 12 angiosarcomas, but not in any of 5 hemangioendotheliomas (epithelioid or infantile kaposiform). These findings establish GLUT1 immunoreactivity as a highly selective and diagnostically useful marker for juvenile hemangiomas. Because high levels of endothelial GLUT1 expression in normal tissue are restricted to microvessels with blood-tissue barrier function, these findings also have implications for the molecular and developmental pathogenic mechanisms of juvenile hemangiomas.
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Affiliation(s)
- P E North
- Department of Pathology, University of Arkansas for Medical Sciences, and Arkansas Children's Hospital, Little Rock 72202, USA
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