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Shan Y, Cen Y, Xu X, Li P, Chen J, Nie Z, Zhang J. The ATP-Binding Cassette Transporter-Mediated Efflux Transport of Ganciclovir at the Blood-Brain Barrier. Eur J Drug Metab Pharmacokinet 2024; 49:609-617. [PMID: 38963639 DOI: 10.1007/s13318-024-00908-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/16/2024] [Indexed: 07/05/2024]
Abstract
BACKGROUND AND OBJECTIVE Recent studies have highlighted the key role of the ATP-binding cassette (ABC) transporters, including the P-glycoprotein (P-gp), the breast cancer resistance protein (BCRP), and the multi-drug resistance protein 4 (MRP4) in limiting the brain distribution of several antiviral agents. In this study, we investigated whether the inhibition of these transporters increases the permeability of the blood-brain barrier (BBB) to ganciclovir. METHODS A microdialysis and high-performance liquid chromatographic method was developed to monitor the concentrations of unbound ganciclovir in the brain interstitial fluid and plasma, with and without the administration of ABC transporter inhibitors. Pharmacokinetic parameters, including the area under the plasma concentration-time curve from time 0 to time of the last measurable analyte concentration (AUC0-t,plasma), the area under the brain interstitial fluid concentration-time curve from time 0 to time of the last measurable analyte concentration (AUC0-t,brain), and the unbound brain-to-plasma concentration ratio (Kp,uu,brain) were calculated. RESULTS The mean AUC0-t,plasma, AUC0-t,brain, and Kp,uu,brain in rats who received ganciclovir (30 mg/kg, intraperitoneal) alone were 1090 min·µg/mL, 150 min·µg/mL, and 14%, respectively. After the administration of tariquidar (inhibitor of P-gp), Ko143 (inhibitor of BCRP), or MK-571 (inhibitor of MRP4), the Kp,uu,brain of ganciclovir increased to 31 ± 2.1%, 26 ± 1.3%, and 32 ± 2.0%, respectively. CONCLUSIONS The findings of this study suggest that ABC transporters P-gp, BCRP, and MRP4 mediate the efflux of ganciclovir at the BBB and that the inhibition of these transporters facilitates the penetration of the BBB by ganciclovir.
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MESH Headings
- Ganciclovir/pharmacokinetics
- Animals
- Blood-Brain Barrier/metabolism
- Rats
- Male
- Antiviral Agents/pharmacokinetics
- Antiviral Agents/pharmacology
- ATP-Binding Cassette Transporters/metabolism
- ATP-Binding Cassette Transporters/antagonists & inhibitors
- Rats, Sprague-Dawley
- Biological Transport
- Microdialysis/methods
- Chromatography, High Pressure Liquid/methods
- Brain/metabolism
- ATP Binding Cassette Transporter, Subfamily G, Member 2/metabolism
- ATP Binding Cassette Transporter, Subfamily G, Member 2/antagonists & inhibitors
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors
- Diketopiperazines/pharmacokinetics
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Affiliation(s)
- Yuheng Shan
- Department of Neurology, Characteristic Medical Centre of People's Armed Police Force, Tianjin, 300162, People's Republic of China
| | - Yuying Cen
- Department of Neurology, Beijing Anzhen Hospital, Capital Medical University, Beijing, 100011, People's Republic of China
| | - Xiaojiao Xu
- Department of Neurology, The First Medical Centre, Chinese PLA General Hospital, No. 28, Fuxing Road, Beijing, 100853, People's Republic of China
| | - Ping Li
- Department of Neurology, Characteristic Medical Centre of People's Armed Police Force, Tianjin, 300162, People's Republic of China
| | - Jing Chen
- Department of Neurology, Characteristic Medical Centre of People's Armed Police Force, Tianjin, 300162, People's Republic of China
| | - Zhiyong Nie
- Beijing Institute of Pharmacology and Toxicology, Beijing, 100850, People's Republic of China.
| | - Jiatang Zhang
- Department of Neurology, The First Medical Centre, Chinese PLA General Hospital, No. 28, Fuxing Road, Beijing, 100853, People's Republic of China.
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2
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Salphati L, Pang J, Alicke B, Plise EG, Cheong J, Jaochico A, Olivero AG, Sampath D, Wong S, Zhang X. Preclinical characterization of the absorption and disposition of the brain penetrant PI3K/mTOR inhibitor paxalisib and prediction of its pharmacokinetics and efficacy in human. Xenobiotica 2024; 54:64-74. [PMID: 38197324 DOI: 10.1080/00498254.2024.2303586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 01/06/2024] [Indexed: 01/11/2024]
Abstract
Glioblastoma multiforme (GBM) is the most common primary brain tumour in adults. Available treatments have not markedly improved patient survival in the last twenty years. However, genomic investigations have showed that the PI3K pathway is frequently altered in this glioma, making it a potential therapeutic target.Paxalisib is a brain penetrant PI3K/mTOR inhibitor (mouse Kp,uu 0.31) specifically developed for the treatment of GBM. We characterised the preclinical pharmacokinetics and efficacy of paxalisib and predicted its pharmacokinetics and efficacious dose in humans.Plasma protein binding of paxalisib was low, with the fraction unbound ranging from 0.25 to 0.43 across species. The hepatic clearance of paxalisib was predicted to be low in mice, rats, dogs and humans, and high in monkeys, from hepatocytes incubations. The plasma clearance was low in mice, moderate in rats and high in dogs and monkeys. Oral bioavailability ranged from 6% in monkeys to 76% in rats.The parameters estimated from the pharmacokinetic/pharmacodynamic modelling of the efficacy in the subcutaneous U87 xenograft model combined with the human pharmacokinetics profile predicted by PBPK modelling suggested that a dose of 56 mg may be efficacious in humans. Paxalisib is currently tested in Phase III clinical trials.
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Affiliation(s)
- Laurent Salphati
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc, South San Francisco, CA, USA
| | - Jodie Pang
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc, South San Francisco, CA, USA
| | - Bruno Alicke
- Translational Oncology, Genentech, Inc, South San Francisco, CA, USA
| | - Emile G Plise
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc, South San Francisco, CA, USA
| | - Jonathan Cheong
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc, South San Francisco, CA, USA
| | - Allan Jaochico
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc, South San Francisco, CA, USA
| | | | - Deepak Sampath
- Translational Oncology, Genentech, Inc, South San Francisco, CA, USA
| | - Susan Wong
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc, South San Francisco, CA, USA
| | - Xiaolin Zhang
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc, South San Francisco, CA, USA
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Fu T, Zeng S, Zheng Q, Zhu F. The Important Role of Transporter Structures in Drug Disposition, Efficacy, and Toxicity. Drug Metab Dispos 2023; 51:1316-1323. [PMID: 37295948 DOI: 10.1124/dmd.123.001275] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 05/27/2023] [Accepted: 06/02/2023] [Indexed: 06/12/2023] Open
Abstract
The ATP-binding cassette (ABC) and solute carrier (SLC) transporters are critical determinants of drug disposition, clinical efficacy, and toxicity as they specifically mediate the influx and efflux of various substrates and drugs. ABC transporters can modulate the pharmacokinetics of many drugs via mediating the translocation of drugs across biologic membranes. SLC transporters are important drug targets involved in the uptake of a broad range of compounds across the membrane. However, high-resolution experimental structures have been reported for a very limited number of transporters, which limits the study of their physiologic functions. In this review, we collected structural information on ABC and SLC transporters and described the application of computational methods in structure prediction. Taking P-glycoprotein (ABCB1) and serotonin transporter (SLC6A4) as examples, we assessed the pivotal role of structure in transport mechanisms, details of ligand-receptor interactions, drug selectivity, the molecular mechanisms of drug-drug interactions, and differences caused by genetic polymorphisms. The data collected contributes toward safer and more effective pharmacological treatments. SIGNIFICANCE STATEMENT: The experimental structure of ATP-binding cassette and solute carrier transporters was collected, and the application of computational methods in structure prediction was described. P-glycoprotein and serotonin transporter were used as examples to reveal the pivotal role of structure in transport mechanisms, drug selectivity, the molecular mechanisms of drug-drug interactions, and differences caused by genetic polymorphisms.
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Affiliation(s)
- Tingting Fu
- College of Pharmaceutical Sciences, The Second Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang University, Hangzhou, China (F.Z.); School of Pharmaceutical Sciences, Jilin University, Changchun, China (T.F., Q.Z.); College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China (S.Z., F.Z.); and Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University, Alibaba-Zhejiang University Joint Research Center of Future Digital Healthcare, Hangzhou, China (F.Z.)
| | - Su Zeng
- College of Pharmaceutical Sciences, The Second Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang University, Hangzhou, China (F.Z.); School of Pharmaceutical Sciences, Jilin University, Changchun, China (T.F., Q.Z.); College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China (S.Z., F.Z.); and Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University, Alibaba-Zhejiang University Joint Research Center of Future Digital Healthcare, Hangzhou, China (F.Z.)
| | - Qingchuan Zheng
- College of Pharmaceutical Sciences, The Second Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang University, Hangzhou, China (F.Z.); School of Pharmaceutical Sciences, Jilin University, Changchun, China (T.F., Q.Z.); College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China (S.Z., F.Z.); and Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University, Alibaba-Zhejiang University Joint Research Center of Future Digital Healthcare, Hangzhou, China (F.Z.)
| | - Feng Zhu
- College of Pharmaceutical Sciences, The Second Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang University, Hangzhou, China (F.Z.); School of Pharmaceutical Sciences, Jilin University, Changchun, China (T.F., Q.Z.); College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China (S.Z., F.Z.); and Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University, Alibaba-Zhejiang University Joint Research Center of Future Digital Healthcare, Hangzhou, China (F.Z.)
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4
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Feng D, Zhong G, Zuo Q, Wan Y, Xu W, He C, Lin C, Huang D, Chen F, Huang L. Knockout of ABC transporters by CRISPR/Cas9 contributes to reliable and accurate transporter substrate identification for drug discovery. Front Pharmacol 2022; 13:1015940. [PMID: 36386127 PMCID: PMC9649518 DOI: 10.3389/fphar.2022.1015940] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 10/13/2022] [Indexed: 04/21/2024] Open
Abstract
It is essential to explore the relationship between drugs and transporters in the process of drug development. Strong background signals in nonhuman MDCK or LLC-PK1 cells and overlapping interference of inhibitors or RNAi in human Caco-2 cells mean that an ideal alternative could be to knock out specific transporter genes in Caco-2 cells. However, the application of gene knockout (KO) to Caco-2 cells is challenging because it is still inefficient to obtain rapidly growing Caco-2 subclones with double-allele KO through long-term monoclonal cultivation. Herein, CRISPR/Cas9, a low cost but more efficient and precise gene editing technology, was utilized to singly or doubly knockout the P-gp, BCRP, and MRP2 genes in Caco-2 cells. By combining this with single cell expansion, rapidly growing transporter-deficient subclones were successfully screened and established. Bidirectional transport assays with probe substrates and three protease inhibitors indicated that more reliable and detailed data could be drawn easily with these KO Caco-2 models. The six robust KO Caco-2 subclones could contribute to efficient in vitro drug transport research.
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Affiliation(s)
- Dongyan Feng
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Guorui Zhong
- Bioinformatics Institute, Agency for Science, Technology, and Research (A*STAR), Singapore, Singapore
| | - Qingxia Zuo
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Yanbin Wan
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Wanqing Xu
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Changsheng He
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Cailing Lin
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Dongchao Huang
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Feng Chen
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Lizhen Huang
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
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5
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The next frontier in ADME science: Predicting transporter-based drug disposition, tissue concentrations and drug-drug interactions in humans. Pharmacol Ther 2022; 238:108271. [DOI: 10.1016/j.pharmthera.2022.108271] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 08/05/2022] [Accepted: 08/17/2022] [Indexed: 12/25/2022]
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6
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Pardridge WM. A Historical Review of Brain Drug Delivery. Pharmaceutics 2022; 14:1283. [PMID: 35745855 PMCID: PMC9229021 DOI: 10.3390/pharmaceutics14061283] [Citation(s) in RCA: 63] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/01/2022] [Accepted: 06/07/2022] [Indexed: 12/13/2022] Open
Abstract
The history of brain drug delivery is reviewed beginning with the first demonstration, in 1914, that a drug for syphilis, salvarsan, did not enter the brain, due to the presence of a blood-brain barrier (BBB). Owing to restricted transport across the BBB, FDA-approved drugs for the CNS have been generally limited to lipid-soluble small molecules. Drugs that do not cross the BBB can be re-engineered for transport on endogenous BBB carrier-mediated transport and receptor-mediated transport systems, which were identified during the 1970s-1980s. By the 1990s, a multitude of brain drug delivery technologies emerged, including trans-cranial delivery, CSF delivery, BBB disruption, lipid carriers, prodrugs, stem cells, exosomes, nanoparticles, gene therapy, and biologics. The advantages and limitations of each of these brain drug delivery technologies are critically reviewed.
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Affiliation(s)
- William M Pardridge
- Department of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
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7
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Regional Differences in the Absolute Abundance of Transporters, Receptors and Tight Junction Molecules at the Blood-Arachnoid Barrier and Blood-Spinal Cord Barrier among Cervical, Thoracic and Lumbar Spines in Dogs. Pharm Res 2022; 39:1393-1413. [PMID: 35488144 DOI: 10.1007/s11095-022-03275-1] [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: 11/24/2021] [Accepted: 04/25/2022] [Indexed: 10/18/2022]
Abstract
PURPOSE The purpose of the present study was to quantitatively determine the expression of transporters, receptors and tight junction molecules at the blood-arachnoid barrier (BAB) and blood-spinal cord barrier (BSCB) in cervical, thoracic and lumbar spines from dogs. METHODS The expression levels of 31 transporters, 3 receptors, 1 tight junction protein, and 3 marker proteins in leptomeninges and capillaries isolated from spines (3 male and 2 female dogs) were determined by quantitative Targeted Absolute Proteomics (qTAP). The units were converted from fmol/μg protein to pmol/cm (absolute abundance at the BAB and the BSCB in a 1 cm section of spine). RESULTS The expression of MDR1 and BCRP were greater at the BSCB compared to the BAB (especially in the cervical cord), and the expressions at the lumbar BSCB were lower than that for the cervical BSCB. Among the organic anionic and cationic drug transporters, OAT1, OAT3, MRP1, OCT2 and MATE1/2 were detected only in the BAB, and not at the BSCB). The expression of these transporters was higher in the order: lumbar > thoracic > cervical BAB. The expressions of GLUT1, 4F2hc, EAAT1, 2, PEPT2, CTL1, and MCT1 at the BSCB of the cervical cord were higher than the corresponding values for the cervical BAB, and these values decreased in going down the spinal cord. CONCLUSION These results provide a better understanding of the molecular mechanisms underlying the concentration gradients of drugs and endogenous substances in the cerebrospinal fluid and parenchyma of the spinal cord.
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8
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Pardridge WM. Treatment of Alzheimer's Disease and Blood-Brain Barrier Drug Delivery. Pharmaceuticals (Basel) 2020; 13:E394. [PMID: 33207605 PMCID: PMC7697739 DOI: 10.3390/ph13110394] [Citation(s) in RCA: 84] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 12/12/2022] Open
Abstract
Despite the enormity of the societal and health burdens caused by Alzheimer's disease (AD), there have been no FDA approvals for new therapeutics for AD since 2003. This profound lack of progress in treatment of AD is due to dual problems, both related to the blood-brain barrier (BBB). First, 98% of small molecule drugs do not cross the BBB, and ~100% of biologic drugs do not cross the BBB, so BBB drug delivery technology is needed in AD drug development. Second, the pharmaceutical industry has not developed BBB drug delivery technology, which would enable industry to invent new therapeutics for AD that actually penetrate into brain parenchyma from blood. In 2020, less than 1% of all AD drug development projects use a BBB drug delivery technology. The pathogenesis of AD involves chronic neuro-inflammation, the progressive deposition of insoluble amyloid-beta or tau aggregates, and neural degeneration. New drugs that both attack these multiple sites in AD, and that have been coupled with BBB drug delivery technology, can lead to new and effective treatments of this serious disorder.
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Affiliation(s)
- William M Pardridge
- Department of Medicine, University of California, Los Angeles, CA 90024, USA
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9
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Huang L, Wells MC, Zhao Z. A Practical Perspective on the Evaluation of Small Molecule CNS Penetration in Drug Discovery. Drug Metab Lett 2020; 13:78-94. [PMID: 30854983 DOI: 10.2174/1872312813666190311125652] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 02/20/2019] [Accepted: 03/01/2019] [Indexed: 01/16/2023]
Abstract
The separation of the brain from blood by the blood-brain barrier and the bloodcerebrospinal fluid (CSF) barrier poses unique challenges for the discovery and development of drugs targeting the central nervous system (CNS). This review will describe the role of transporters in CNS penetration and examine the relationship between unbound brain (Cu-brain) and unbound plasma (Cu-plasma) or CSF (CCSF) concentration. Published data demonstrate that the relationship between Cu-brain and Cu-plasma or CCSF can be affected by transporter status and passive permeability of a drug and CCSF may not be a reliable surrogate for CNS penetration. Indeed, CCSF usually over-estimates Cu-brain for efflux substrates and it provides no additional value over Cu-plasma as the surrogate of Cu-brain for highly permeable non-efflux substrates. A strategy described here for the evaluation of CNS penetration is to use in vitro permeability, P-glycoprotein (Pgp) and breast cancer resistance protein efflux assays and Cu-brain/Cu-plasma in preclinical species. Cu-plasma should be used as the surrogate of Cu-brain for highly permeable non-efflux substrates with no evidence of impaired distribution into the brain. When drug penetration into the brain is impaired, we recommend using (total brain concentration * unbound fraction in the brain) as Cu-brain in preclinical species or Cu-plasma/in vitro Pgp efflux ratio if Pgp is the major limiting mechanism for brain penetration.
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Affiliation(s)
- Liyue Huang
- Epizyme Inc, 400 Technology Square, Cambridge, MA-02139, United States
| | - Mary C Wells
- Vertex Pharmaceuticals, 50 Northern Ave, Boston, MA-02210, United States
| | - Zhiyang Zhao
- Alliance Pharma, Inc. 17 Lee Blvd. Malvern, PA-19355, United States
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10
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Pardridge WM. The Isolated Brain Microvessel: A Versatile Experimental Model of the Blood-Brain Barrier. Front Physiol 2020; 11:398. [PMID: 32457645 PMCID: PMC7221163 DOI: 10.3389/fphys.2020.00398] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Accepted: 04/02/2020] [Indexed: 12/12/2022] Open
Abstract
A versatile experimental model for the investigation of the blood-brain barrier (BBB), including the neuro-vascular unit, is the isolated brain microvessel preparation. Brain microvessels are primarily comprised of endothelial cells, but also include pericytes, pre-capillary arteriolar smooth muscle cells, astrocyte foot processes, and occasional nerve endings. These microvessels can be isolated from brain with a 3 h procedure, and the microvessels are free of brain parenchyma. Brain microvessels have been isolated from fresh animal brain, fresh human brain obtained at neurosurgery, as well as fresh or frozen autopsy human brain. Brain microvessels are the starting point for isolation of brain microvessel RNA, which then enables the production of BBB cDNA libraries and a genomics analysis of the brain microvasculature. Brain microvessels, combined with quantitative targeted absolute proteomics, allow for the quantitation of specific transporters or receptors expressed at the brain microvasculature. Brain microvessels, combined with specific antibodies and immune labeling of isolated capillaries, allow for the cellular location of proteins expressed within the neuro-vascular unit. Isolated brain microvessels can be used as an “in vitro” preparation of the BBB for the study of the kinetic parameters of BBB carrier-mediated transport (CMT) systems, or for the determination of dissociation constants of peptide binding to BBB receptor-mediated transport (RMT) systems expressed at either the animal or the human BBB. This review will discuss how the isolated brain microvessel model system has advanced our understanding of the organization and functional properties of the BBB, and highlight recent renewed interest in this 50 year old model of the BBB.
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Affiliation(s)
- William M Pardridge
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
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11
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Pardridge WM. Blood-Brain Barrier and Delivery of Protein and Gene Therapeutics to Brain. Front Aging Neurosci 2020; 11:373. [PMID: 31998120 PMCID: PMC6966240 DOI: 10.3389/fnagi.2019.00373] [Citation(s) in RCA: 209] [Impact Index Per Article: 52.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 12/19/2019] [Indexed: 01/02/2023] Open
Abstract
Alzheimer’s disease (AD) and treatment of the brain in aging require the development of new biologic drugs, such as recombinant proteins or gene therapies. Biologics are large molecule therapeutics that do not cross the blood-brain barrier (BBB). BBB drug delivery is the limiting factor in the future development of new therapeutics for the brain. The delivery of recombinant protein or gene medicines to the brain is a binary process: either the brain drug developer re-engineers the biologic with BBB drug delivery technology, or goes forward with brain drug development in the absence of a BBB delivery platform. The presence of BBB delivery technology allows for engineering the therapeutic to enable entry into the brain across the BBB from blood. Brain drug development may still take place in the absence of BBB delivery technology, but with a reliance on approaches that have rarely led to FDA approval, e.g., CSF injection, stem cells, small molecules, and others. CSF injection of drug is the most widely practiced approach to brain delivery that bypasses the BBB. However, drug injection into the CSF results in limited drug penetration to the brain parenchyma, owing to the rapid export of CSF from the brain to blood. A CSF injection of a drug is equivalent to a slow intravenous (IV) infusion of the pharmaceutical. Given the profound effect the existence of the BBB has on brain drug development, future drug or gene development for the brain will be accelerated by future advances in BBB delivery technology in parallel with new drug discovery.
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Affiliation(s)
- William M Pardridge
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
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12
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Uchida Y, Goto R, Takeuchi H, Łuczak M, Usui T, Tachikawa M, Terasaki T. Abundant Expression of OCT2, MATE1, OAT1, OAT3, PEPT2, BCRP, MDR1, and xCT Transporters in Blood-Arachnoid Barrier of Pig and Polarized Localizations at CSF- and Blood-Facing Plasma Membranes. Drug Metab Dispos 2019; 48:135-145. [PMID: 31771948 DOI: 10.1124/dmd.119.089516] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 11/19/2019] [Indexed: 11/22/2022] Open
Abstract
The physiologic and pharmacologic roles of the blood-arachnoid barrier (BAB) remain unclear. Therefore, the purpose of the present study was to comprehensively evaluate and compare the absolute protein expression levels of transporters in the leptomeninges and plexus per cerebrum, and to determine the localizations of transporters at the cerebrospinal fluid (CSF)-facing and blood (dura)-facing plasma membranes of the BAB in pig. Using multidrug resistance protein 1 (MDR1) and organic anion transporter (OAT) 1 as blood (dura)-facing and CSF-facing plasma membrane marker proteins, respectively, we established that breast cancer resistance protein (BCRP), multidrug resistance-associated protein (MRP) 4, organic anion-transporting polypeptide (OATP) 2B1, multidrug and toxin extrusion protein 1 (MATE1), and glucose transporter 1 (GLUT1) are localized at the blood-facing plasma membrane, and OAT3, peptide transporter (PEPT) 2, MRP3, organic cation transporter (OCT) 2, xCT, monocarboxylate transporter (MCT) 1, MCT4, and MCT8 are localized at the CSF-facing plasma membrane of the BAB. The absolute protein expression levels of OAT1, OAT3, MDR1, BCRP, PEPT2, xCT, MATE1, OCT2, and 4f2hc in the whole BAB surrounding the entire cerebrum were much larger than those in the total of the choroid plexuses forming the blood-cerebrospinal fluid barrier (BCSFB). Although MRP4, OATP2B1, MCT8, GLUT1, and MCT1 were also statistically significantly more abundant in the BAB than in the choroid plexuses per porcine cerebrum, these transporters were nevertheless almost equally distributed between the two barriers. In contrast, OATP1A2, MRP1, OATP3A1, and OCTN2 were specifically expressed in the choroid plexus. These results should be helpful in understanding the relative overall importance of transport at the BAB compared with that at the BCSFB, as well as the rank order of transport capacities among different transporters at the BAB, and the directions of transport mediated by individual transporters. SIGNIFICANCE STATEMENT: We found that BCRP, MRP4, OATP2B1, MATE1, and GLUT1 localize at the blood-facing plasma membrane of the blood-arachnoid barrier (BAB), while OAT3, PEPT2, MRP3, OCT2, xCT, MCT1, MCT4, and MCT8 localize at the CSF-facing plasma membrane. 4F2hc is expressed in both membranes. For OAT1, OAT3, MDR1, BCRP, PEPT2, xCT, MATE1, OCT2, and 4f2hc, the absolute protein expression levels in the whole BAB surrounding the entire cerebrum are much greater than the total amounts in the choroid plexuses.
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Affiliation(s)
- Yasuo Uchida
- Graduate School of Pharmaceutical Sciences (Y.U., M.Ł., T.U., M.T., T.T.) and Faculty of Pharmaceutical Sciences (Y.U., R.G., H.T., M.T., T.T.), Tohoku University, Sendai, Japan; and Institute of Bioorganic Chemistry, Polish Academy of Sciences, Warsaw, Poland (M.Ł.)
| | - Ryohei Goto
- Graduate School of Pharmaceutical Sciences (Y.U., M.Ł., T.U., M.T., T.T.) and Faculty of Pharmaceutical Sciences (Y.U., R.G., H.T., M.T., T.T.), Tohoku University, Sendai, Japan; and Institute of Bioorganic Chemistry, Polish Academy of Sciences, Warsaw, Poland (M.Ł.)
| | - Hina Takeuchi
- Graduate School of Pharmaceutical Sciences (Y.U., M.Ł., T.U., M.T., T.T.) and Faculty of Pharmaceutical Sciences (Y.U., R.G., H.T., M.T., T.T.), Tohoku University, Sendai, Japan; and Institute of Bioorganic Chemistry, Polish Academy of Sciences, Warsaw, Poland (M.Ł.)
| | - Magdalena Łuczak
- Graduate School of Pharmaceutical Sciences (Y.U., M.Ł., T.U., M.T., T.T.) and Faculty of Pharmaceutical Sciences (Y.U., R.G., H.T., M.T., T.T.), Tohoku University, Sendai, Japan; and Institute of Bioorganic Chemistry, Polish Academy of Sciences, Warsaw, Poland (M.Ł.)
| | - Takuya Usui
- Graduate School of Pharmaceutical Sciences (Y.U., M.Ł., T.U., M.T., T.T.) and Faculty of Pharmaceutical Sciences (Y.U., R.G., H.T., M.T., T.T.), Tohoku University, Sendai, Japan; and Institute of Bioorganic Chemistry, Polish Academy of Sciences, Warsaw, Poland (M.Ł.)
| | - Masanori Tachikawa
- Graduate School of Pharmaceutical Sciences (Y.U., M.Ł., T.U., M.T., T.T.) and Faculty of Pharmaceutical Sciences (Y.U., R.G., H.T., M.T., T.T.), Tohoku University, Sendai, Japan; and Institute of Bioorganic Chemistry, Polish Academy of Sciences, Warsaw, Poland (M.Ł.)
| | - Tetsuya Terasaki
- Graduate School of Pharmaceutical Sciences (Y.U., M.Ł., T.U., M.T., T.T.) and Faculty of Pharmaceutical Sciences (Y.U., R.G., H.T., M.T., T.T.), Tohoku University, Sendai, Japan; and Institute of Bioorganic Chemistry, Polish Academy of Sciences, Warsaw, Poland (M.Ł.)
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13
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Santerre M, Wang Y, Arjona S, Allen C, Sawaya BE. Differential Contribution of HIV-1 Subtypes B and C to Neurological Disorders: Mechanisms and Possible Treatments. AIDS Rev 2019; 21:76-83. [PMID: 31332398 DOI: 10.24875/aidsrev.19000051] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
With the introduction of combinatory antiretroviral therapy, patients infected with human immunodeficiency virus type 1 (HIV-1) can live much longer than before. However, the identification of HIV-associated neurocognitive disorder (HAND), especially HIV-associated dementia in 15-20% of patients infected with HIV-1, indicates additional complexity. These disorders turn out to be subtype dependent. Recently, many studies are ongoing trying to understand how the virus induces neuronal injury which could lead to neurological dysfunction. Most of these studies are focusing on the HIV-1 release of proteins such as Tat. However, the exact role of these proteins and their involvement in neuronal degeneration remains unidentified; this is especially true since viral proteins from different HIV-1 subtypes differ in their ability to cause neuronal damage. This review describes the role of different HIV-1 subtypes, identifies probable pathways involved in neuronal damage, the contribution of different HIV-1 subtypes to the progression of HAND, and potential treatments for HAND.
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Affiliation(s)
- Maryline Santerre
- Molecular Studies of Neurodegenerative Diseases Lab, FELS Institute for Cancer Research and Molecular Biology, Philadelphia, Pennsylvania, USA
| | - Ying Wang
- Molecular Studies of Neurodegenerative Diseases Lab, FELS Institute for Cancer Research and Molecular Biology, Philadelphia, Pennsylvania, USA
| | - Sterling Arjona
- Molecular Studies of Neurodegenerative Diseases Lab, FELS Institute for Cancer Research and Molecular Biology, Philadelphia, Pennsylvania, USA
| | - Charles Allen
- Molecular Studies of Neurodegenerative Diseases Lab, FELS Institute for Cancer Research and Molecular Biology, Philadelphia, Pennsylvania, USA
| | - Bassel E Sawaya
- Department of Neurology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
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14
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Zhang Z, Tachikawa M, Uchida Y, Terasaki T. Drug Clearance from Cerebrospinal Fluid Mediated by Organic Anion Transporters 1 (Slc22a6) and 3 (Slc22a8) at Arachnoid Membrane of Rats. Mol Pharm 2018; 15:911-922. [PMID: 29436232 DOI: 10.1021/acs.molpharmaceut.7b00852] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Although arachnoid mater epithelial cells form the blood-arachnoid barrier (BAB), acting as a blood-CSF interface, it has been generally considered that the BAB is impermeable to water-soluble substances and plays a largely passive role. Here, we aimed to clarify the function of transporters at the BAB in regulating CSF clearance of water-soluble organic anion drugs based on quantitative targeted absolute proteomics (QTAP) and in vivo analyses. Protein expression levels of 61 molecules, including 19 ATP-binding-cassette (ABC) transporters and 32 solute-carrier (SLC) transporters, were measured in plasma membrane fraction of rat leptomeninges using QTAP. Thirty-three proteins were detected; others were under the quantification limits. Expression levels of multidrug resistance protein 1 (Mdr1a/P-gp/Abcb1a) and breast cancer resistance protein (Bcrp/Abcg2) were 16.6 and 3.27 fmol/μg protein (51.9- and 9.82-fold greater than in choroid plexus, respectively). Among those organic anion transporters detected only at leptomeninges, not choroid plexus, organic anion transporter 1 (oat1/Slc22a6) showed the greatest expression (2.73 fmol/μg protein). On the other hand, the protein expression level of oat3 at leptomeninges was 6.65 fmol/μg protein, and the difference from choroid plexus was within two-fold. To investigate oat1's role, we injected para-aminohippuric acid (PAH) with or without oat1 inhibitors into cisterna magna (to minimize the contribution of choroid plexus function) of rats. A bulk flow marker, FITC-inulin, was not taken up from CSF up to 15 min, whereas uptake clearance of PAH was 26.5 μL/min. PAH uptake was completely blocked by 3 mM cephalothin (inhibits both oat1 and oat3), while 17% of PAH uptake was inhibited by 0.2 mM cephalothin (selectively inhibits oat3). These results indicate that oat1 and oat3 at the BAB provide a distinct clearance pathway of organic anion drugs from CSF independently of choroid plexus.
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Affiliation(s)
- Zhengyu Zhang
- Division of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical Sciences , Tohoku University , Sendai 980-8578 , Japan
| | - Masanori Tachikawa
- Division of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical Sciences , Tohoku University , Sendai 980-8578 , Japan
| | - Yasuo Uchida
- Division of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical Sciences , Tohoku University , Sendai 980-8578 , Japan
| | - Tetsuya Terasaki
- Division of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical Sciences , Tohoku University , Sendai 980-8578 , Japan
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15
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Tan J, Li M, Zhong W, Hu C, Gu Q, Xie Y. Tyrosine kinase inhibitors show different anti-brain metastases efficacy in NSCLC: A direct comparative analysis of icotinib, gefitinib, and erlotinib in a nude mouse model. Oncotarget 2017; 8:98771-98781. [PMID: 29228726 PMCID: PMC5716766 DOI: 10.18632/oncotarget.21936] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Accepted: 08/26/2017] [Indexed: 12/27/2022] Open
Abstract
Brain metastasis is an increasing problem in non-small cell lung cancer (NSCLC) patients. Tyrosine kinase inhibitors (TKIs), including gefitinib, erlotinib, and icotinib, are reported to be effective in patients with brain metastases. However, direct comparative studies of the pharmacokinetics and efficacy of these three drugs in treating brain metastases are lacking. In the present investigation, we found that gefitinib penetrated the blood-tumor barrier and was distributed to brain metastases more effectively than erlotinib or icotinib in a nude mouse model. The 1-h ratio of brain metastases to plasma concentration for gefitinib, erlotinib, and icotinib was 9.82±1.03%, 4.83±0.25%, and 2.62±0.21%, respectively. The 2-h ratio of brain metastases to plasma concentration for gefitinib, erlotinib, and icotinib was 15.11±2.00%, 5.73±1.31%, and 2.69±0.31%, respectively. Gefitinib exhibited the strongest antitumor activity (pgefitinib vs. erlotinib=0.005; pgefitinib vs. icotinib=0.002). Notably, erlotinib exhibited a better treatment efficacy than icotinib (p=0.037). Consistently, immunohistochemical data showed that TKIs differentially inhibit the proliferation of metastatical tumor cells. Gefitinib and erlotinib markedly inhibited the proliferation of tumor cells, while there were more ki-67-positive tumor cells in the icotinib group. Additionally, gefitinib inhibited the phosphorylation of EGFR better than the other drugs, whereas pEGFR expression levels in erlotinib groups were lower than levels in the icotinib group (pgefitinib vs. erlotinib=0.995; pgefitinib vs. icotinib=0.028; perlotinib vs. icotinib=0.042).Altogether, our findings suggest that gefitinib and erlotinib can inhibit the growth of PC-9-luc brain tumors. Gefitinib demonstrated better antitumor activity and penetration rate in brain metastases than erlotinib or icotinib.
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Affiliation(s)
- Jianlong Tan
- Department of Respiratory Medicine, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Min Li
- Department of Respiratory Medicine, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Wen Zhong
- Department of Respiratory Medicine, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Chengping Hu
- Department of Respiratory Medicine, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Qihua Gu
- Department of Respiratory Medicine, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Yali Xie
- Department of Respiratory Medicine, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
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16
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Marchitti SA, Mazur CS, Dillingham CM, Rawat S, Sharma A, Zastre J, Kenneke JF. Inhibition of the Human ABC Efflux Transporters P-gp and BCRP by the BDE-47 Hydroxylated Metabolite 6-OH-BDE-47: Considerations for Human Exposure. Toxicol Sci 2016; 155:270-282. [PMID: 28031414 DOI: 10.1093/toxsci/kfw209] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
High body burdens of polybrominated diphenyl ethers (PBDEs) in infants and young children have led to increased concern over their potential impact on human development. PBDE exposure can alter the expression of genes involved in thyroid homeostasis, including those of ATP-binding cassette (ABC) transporters, which mediate cellular xenobiotic efflux. However, little information exists on how PBDEs interact with ABC transporters such as P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). The purpose of this study was to evaluate the interactions of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) and its hydroxylated metabolite 6-OH-BDE-47 with P-gp and BCRP, using human MDR1- and BCRP-expressing membrane vesicles and stably transfected NIH-3T3-MDR1 and MDCK-BCRP cells. In P-gp membranes, BDE-47 did not affect P-gp activity; however, 6-OH-BDE-47 inhibited P-gp activity at low µM concentrations (IC50 = 11.7 µM). In BCRP membranes, BDE-47 inhibited BCRP activity; however, 6-OH-BDE-47 was a stronger inhibitor [IC50 = 45.9 µM (BDE-47) vs. IC50 = 9.4 µM (6-OH-BDE-47)]. Intracellular concentrations of known P-gp and BCRP substrates [(3H)-paclitaxel and (3H)-prazosin, respectively] were significantly higher (indicating less efflux) in NIH-3T3-MDR1 and MDCK-BCRP cells in the presence of 6-OH-BDE-47, but not BDE-47. Collectively, our results indicate that the BDE-47 metabolite 6-OH-BDE-47 is an inhibitor of both P-gp and BCRP efflux activity. These findings suggest that some effects previously attributed to BDE-47 in biological systems may actually be due to 6-OH-BDE-47. Considerations for human exposure are discussed.
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Affiliation(s)
- Satori A Marchitti
- U.S. Environmental Protection Agency, National Exposure Research Laboratory, Athens, Georgia 30605
| | - Christopher S Mazur
- U.S. Environmental Protection Agency, National Exposure Research Laboratory, Athens, Georgia 30605
| | - Caleb M Dillingham
- U.S. Environmental Protection Agency, National Exposure Research Laboratory, Athens, Georgia 30605
| | - Swati Rawat
- U.S. Environmental Protection Agency, National Exposure Research Laboratory, Athens, Georgia 30605
| | - Anshika Sharma
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia 30602
| | - Jason Zastre
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia 30602
| | - John F Kenneke
- U.S. Environmental Protection Agency, National Exposure Research Laboratory, Athens, Georgia 30605;
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Pharmacokinetic, Pharmacogenetic, and Other Factors Influencing CNS Penetration of Antiretrovirals. AIDS Res Treat 2016; 2016:2587094. [PMID: 27777797 PMCID: PMC5061948 DOI: 10.1155/2016/2587094] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 08/21/2016] [Indexed: 12/22/2022] Open
Abstract
Neurological complications associated with the human immunodeficiency virus (HIV) are a matter of great concern. While antiretroviral (ARV) drugs are the cornerstone of HIV treatment and typically produce neurological benefit, some ARV drugs have limited CNS penetration while others have been associated with neurotoxicity. CNS penetration is a function of several factors including sieving role of blood-brain and blood-CSF barriers and activity of innate drug transporters. Other factors are related to pharmacokinetics and pharmacogenetics of the specific ARV agent or mediated by drug interactions, local inflammation, and blood flow. In this review, we provide an overview of the various factors influencing CNS penetration of ARV drugs with an emphasis on those commonly used in sub-Saharan Africa. We also summarize some key associations between ARV drug penetration, CNS efficacy, and neurotoxicity.
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18
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Alam C, Whyte-Allman SK, Omeragic A, Bendayan R. Role and modulation of drug transporters in HIV-1 therapy. Adv Drug Deliv Rev 2016; 103:121-143. [PMID: 27181050 DOI: 10.1016/j.addr.2016.05.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 04/29/2016] [Accepted: 05/03/2016] [Indexed: 12/15/2022]
Abstract
Current treatment of human immunodeficiency virus type-1 (HIV-1) infection involves a combination of antiretroviral drugs (ARVs) that target different stages of the HIV-1 life cycle. This strategy is commonly referred to as highly active antiretroviral therapy (HAART) or combined antiretroviral therapy (cART). Membrane-associated drug transporters expressed ubiquitously in mammalian systems play a crucial role in modulating ARV disposition during HIV-1 infection. Members of the ATP-binding cassette (ABC) and solute carrier (SLC) transporter superfamilies have been shown to interact with ARVs, including those that are used as part of first-line treatment regimens. As a result, the functional expression of drug transporters can influence the distribution of ARVs at specific sites of infection. In addition, pathological factors related to HIV-1 infection and/or ARV therapy itself can alter transporter expression and activity, thus further contributing to changes in ARV disposition and the effectiveness of HAART. This review summarizes current knowledge on the role of drug transporters in regulating ARV transport in the context of HIV-1 infection.
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Affiliation(s)
- Camille Alam
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 2S2, Canada
| | - Sana-Kay Whyte-Allman
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 2S2, Canada
| | - Amila Omeragic
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 2S2, Canada
| | - Reina Bendayan
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 2S2, Canada.
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20
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Liu L, Collier AC, Link JM, Domino KB, Mankoff DA, Eary JF, Spiekerman CF, Hsiao P, Deo AK, Unadkat JD. Modulation of P-glycoprotein at the Human Blood-Brain Barrier by Quinidine or Rifampin Treatment: A Positron Emission Tomography Imaging Study. Drug Metab Dispos 2015; 43:1795-804. [PMID: 26354948 DOI: 10.1124/dmd.114.058685] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 09/01/2015] [Indexed: 11/22/2022] Open
Abstract
Permeability-glycoprotein (P-glycoprotein, P-gp), an efflux transporter at the human blood-brain barrier (BBB), is a significant obstacle to central nervous system (CNS) delivery of P-gp substrate drugs. Using positron emission tomography imaging, we investigated P-gp modulation at the human BBB by an approved P-gp inhibitor, quinidine, or the P-gp inducer, rifampin. Cerebral blood flow (CBF) and BBB P-gp activity were respectively measured by administration of (15)O-water followed by (11)C-verapamil. In a crossover design, healthy volunteers received quinidine and 11-29 days of rifampin treatment during different study periods. CBF and P-gp activity was measured in the absence (control; prior to quinidine treatment) and presence of P-gp modulation. At clinically relevant quinidine plasma concentrations, P-gp inhibition resulted in a 60% increase in (11)C-radioactivity distribution across the human BBB as measured by the brain extraction ratio (ER) of (11)C-radioactivity. Furthermore, the magnitude of BBB P-gp inhibition by quinidine was successfully predicted by a combination of in vitro and macaque data, but not by rat data. Although our findings demonstrated that quinidine did not completely inhibit P-gp at the human BBB, it has the potential to produce clinically significant CNS drug interactions with P-gp substrate drugs that exhibit a narrow therapeutic window and are significantly excluded from the brain by P-gp. Rifampin treatment induced systemic CYP3A metabolism of (11)C-verapamil; however, it reduced the ER by 6%. Therefore, we conclude that rifampin, at its usual clinical dose, cannot be used to induce P-gp at the human BBB to a clinically meaningful extent and is unlikely to cause inadvertent BBB-inductive drug interactions.
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Affiliation(s)
- Li Liu
- Department of Pharmaceutics (L.L., P.H., A.K.D., J.D.U.), Department of Medicine (A.C.C.), Division of Nuclear Medicine (J.M.L., D.A.M., J.F.E.), Department of Anesthesiology and Pain Medicine (K.B.D.), and Department of Oral Health Sciences (C.F.S.), University of Washington, Seattle, Washington
| | - Ann C Collier
- Department of Pharmaceutics (L.L., P.H., A.K.D., J.D.U.), Department of Medicine (A.C.C.), Division of Nuclear Medicine (J.M.L., D.A.M., J.F.E.), Department of Anesthesiology and Pain Medicine (K.B.D.), and Department of Oral Health Sciences (C.F.S.), University of Washington, Seattle, Washington
| | - Jeanne M Link
- Department of Pharmaceutics (L.L., P.H., A.K.D., J.D.U.), Department of Medicine (A.C.C.), Division of Nuclear Medicine (J.M.L., D.A.M., J.F.E.), Department of Anesthesiology and Pain Medicine (K.B.D.), and Department of Oral Health Sciences (C.F.S.), University of Washington, Seattle, Washington
| | - Karen B Domino
- Department of Pharmaceutics (L.L., P.H., A.K.D., J.D.U.), Department of Medicine (A.C.C.), Division of Nuclear Medicine (J.M.L., D.A.M., J.F.E.), Department of Anesthesiology and Pain Medicine (K.B.D.), and Department of Oral Health Sciences (C.F.S.), University of Washington, Seattle, Washington
| | - David A Mankoff
- Department of Pharmaceutics (L.L., P.H., A.K.D., J.D.U.), Department of Medicine (A.C.C.), Division of Nuclear Medicine (J.M.L., D.A.M., J.F.E.), Department of Anesthesiology and Pain Medicine (K.B.D.), and Department of Oral Health Sciences (C.F.S.), University of Washington, Seattle, Washington
| | - Janet F Eary
- Department of Pharmaceutics (L.L., P.H., A.K.D., J.D.U.), Department of Medicine (A.C.C.), Division of Nuclear Medicine (J.M.L., D.A.M., J.F.E.), Department of Anesthesiology and Pain Medicine (K.B.D.), and Department of Oral Health Sciences (C.F.S.), University of Washington, Seattle, Washington
| | - Charles F Spiekerman
- Department of Pharmaceutics (L.L., P.H., A.K.D., J.D.U.), Department of Medicine (A.C.C.), Division of Nuclear Medicine (J.M.L., D.A.M., J.F.E.), Department of Anesthesiology and Pain Medicine (K.B.D.), and Department of Oral Health Sciences (C.F.S.), University of Washington, Seattle, Washington
| | - Peng Hsiao
- Department of Pharmaceutics (L.L., P.H., A.K.D., J.D.U.), Department of Medicine (A.C.C.), Division of Nuclear Medicine (J.M.L., D.A.M., J.F.E.), Department of Anesthesiology and Pain Medicine (K.B.D.), and Department of Oral Health Sciences (C.F.S.), University of Washington, Seattle, Washington
| | - Anand K Deo
- Department of Pharmaceutics (L.L., P.H., A.K.D., J.D.U.), Department of Medicine (A.C.C.), Division of Nuclear Medicine (J.M.L., D.A.M., J.F.E.), Department of Anesthesiology and Pain Medicine (K.B.D.), and Department of Oral Health Sciences (C.F.S.), University of Washington, Seattle, Washington
| | - Jashvant D Unadkat
- Department of Pharmaceutics (L.L., P.H., A.K.D., J.D.U.), Department of Medicine (A.C.C.), Division of Nuclear Medicine (J.M.L., D.A.M., J.F.E.), Department of Anesthesiology and Pain Medicine (K.B.D.), and Department of Oral Health Sciences (C.F.S.), University of Washington, Seattle, Washington
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Calcagno A, Di Perri G, Bonora S. Pharmacokinetics and pharmacodynamics of antiretrovirals in the central nervous system. Clin Pharmacokinet 2015; 53:891-906. [PMID: 25200312 DOI: 10.1007/s40262-014-0171-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
HIV-positive patients may be effectively treated with highly active antiretroviral therapy and such a strategy is associated with striking immune recovery and viral load reduction to very low levels. Despite undeniable results, the central nervous system (CNS) is commonly affected during the course of HIV infection, with neurocognitive disorders being as prevalent as 20-50 % of treated subjects. This review discusses the pathophysiology of CNS infection by HIV and the barriers to efficacious control of such a mechanism, including the available data on compartmental drug penetration and on pharmacokinetic/pharmacodynamic relationships. In the reviewed articles, a high variability in drug transfer to the CNS is highlighted with several mechanisms as well as methodological issues potentially influencing the observed results. Nevirapine and zidovudine showed the highest cerebrospinal fluid (CSF) to plasma ratios, although target concentrations are currently unknown for the CNS. The use of the composite CSF concentration effectiveness score has been associated with better virological outcomes (lower HIV RNA) but has been inconsistently associated with neurocognitive outcomes. These findings support the CNS effectiveness of commonly used highly antiretroviral therapies. The use of antiretroviral drugs with increased CSF penetration and/or effectiveness in treating or preventing neurocognitive disorders however needs to be assessed in well-designed prospective studies.
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Affiliation(s)
- Andrea Calcagno
- Unit of Infectious Diseases, Department of Medical Sciences, University of Torino, c/o Ospedale Amedeo di Savoia, C.so Svizzera 164, 10159, Torino, Italy,
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Krishnamurthy S, Tichenor MD, Satish AG, Lehmann DB. A proposed role for efflux transporters in the pathogenesis of hydrocephalus. Croat Med J 2015; 55:366-76. [PMID: 25165050 PMCID: PMC4157374 DOI: 10.3325/cmj.2014.55.366] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Hydrocephalus is a common brain disorder that is treated only with surgery. The basis for surgical treatment rests on the circulation theory. However, clinical and experimental data to substantiate circulation theory have remained inconclusive. In brain tissue and in the ventricles, we see that osmotic gradients drive water diffusion in water-permeable tissue. As the osmolarity of ventricular CSF increases within the cerebral ventricles, water movement into the ventricles increases and causes hydrocephalus. Macromolecular clearance from the ventricles is a mechanism to establish the normal CSF osmolarity, and therefore ventricular volume. Efflux transporters, (p-glycoprotein), are located along the blood brain barrier and play an important role in the clearance of macromolecules (endobiotics and xenobiotics) from the brain to the blood. There is clinical and experimental data to show that macromolecules are cleared out of the brain in normal and hydrocephalic brains. This article summarizes the existing evidence to support the role of efflux transporters in the pathogenesis of hydrocephalus. The location of p-gp along the pathways of macromolecular clearance and the broad substrate specificity of this abundant transporter to a variety of different macromolecules are reviewed. Involvement of p-gp in the transport of amyloid beta in Alzheimer disease and its relation to normal pressure hydrocephalus is reviewed. Finally, individual variability of p-gp expression might explain the variability in the development of hydrocephalus following intraventricular hemorrhage.
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23
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Ashraf T, Jiang W, Hoque MT, Henderson J, Wu C, Bendayan R. Role of anti-inflammatory compounds in human immunodeficiency virus-1 glycoprotein120-mediated brain inflammation. J Neuroinflammation 2014; 11:91. [PMID: 24884548 PMCID: PMC4046047 DOI: 10.1186/1742-2094-11-91] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 04/15/2014] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Neuroinflammation is a common immune response associated with brain human immunodeficiency virus-1 (HIV-1) infection. Identifying therapeutic compounds that exhibit better brain permeability and can target signaling pathways involved in inflammation may benefit treatment of HIV-associated neurological complications. The objective of this study was to implement an in vivo model of brain inflammation by intracerebroventricular administration of the HIV-1 viral coat protein gp120 in rats and to examine anti-inflammatory properties of HIV adjuvant therapies such as minocycline, chloroquine and simvastatin. METHODS Male Wistar rats were administered a single dose of gp120ADA (500 ng) daily for seven consecutive days, intracerebroventricularly, with or without prior intraperitoneal administration of minocycline, chloroquine or simvastatin. Maraviroc, a CCR5 antagonist, was administered intracerebroventricularly prior to gp120 administration for seven days as control. Real-time qPCR was used to assess gene expression of inflammatory markers in the frontal cortex, hippocampus and striatum. Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) secretion in cerebrospinal fluid (CSF) was measured applying ELISA. Protein expression of mitogen-activated protein kinases (MAPKs) (extracellular signal-related kinase 1/2 (ERK1/2), c-Jun N-terminal kinases (JNKs) and P38 kinases (P38Ks)) was detected using immunoblot analysis. Student's t-test and ANOVA were applied to determine statistical significance. RESULTS In gp120ADA-injected rats, mRNA transcripts of interleukin-1β (IL-1β) and inducible nitric oxide synthase (iNOS) were significantly elevated in the frontal cortex, striatum and hippocampus compared to saline or heat-inactivated gp120-injected controls. In CSF, a significant increase in TNF-α and IL-1β was detected. Maraviroc reduced upregulation of these markers suggesting that the interaction of R5-tropic gp120 to CCR5 chemokine receptor is critical for induction of an inflammatory response. Minocycline, chloroquine or simvastatin attenuated upregulation of IL-1β and iNOS transcripts in different brain regions. In CSF, minocycline suppressed TNF-α and IL-1β secretion, whereas chloroquine attenuated IL-1β secretion. In gp120-injected animals, activation of ERK1/2 and JNKs was observed in the hippocampus and ERK1/2 activation was significantly reduced by the anti-inflammatory agents. CONCLUSIONS Our data demonstrate that anti-inflammatory compounds can completely or partially reverse gp120-associated brain inflammation through an interaction with MAPK signaling pathways and suggest their potential role in contributing towards the prevention and treatment of HIV-associated neurological complications.
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Affiliation(s)
- Tamima Ashraf
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Room 1001, Toronto, ON M5S 3 M2, Canada
| | - Wenlei Jiang
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Room 1001, Toronto, ON M5S 3 M2, Canada
| | - Md Tozammel Hoque
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Room 1001, Toronto, ON M5S 3 M2, Canada
| | - Jeffrey Henderson
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Room 1001, Toronto, ON M5S 3 M2, Canada
| | - Chiping Wu
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Room 1001, Toronto, ON M5S 3 M2, Canada
| | - Reina Bendayan
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Room 1001, Toronto, ON M5S 3 M2, Canada
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Antiretroviral Protease Inhibitors Accelerate Glutathione Export from Viable Cultured Rat Neurons. Neurochem Res 2014; 39:883-92. [DOI: 10.1007/s11064-014-1284-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 03/13/2014] [Indexed: 10/25/2022]
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Predicting the outer boundaries of P-glycoprotein (P-gp)-based drug interactions at the human blood-brain barrier based on rat studies. Mol Pharm 2014; 11:436-44. [PMID: 24364805 DOI: 10.1021/mp400396k] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Using positron emission tomography (PET), (11)C-verapamil as the P-gp substrate, and cyclosporine A (CsA) as the P-gp inhibitor, we showed that the magnitude of P-gp-based drug interactions at the human blood-brain barrier (BBB) is modest. However, such interactions at clinically relevant CsA blood concentrations may be greater for substrates where P-gp plays an even larger role (fractional contribution of P-gp, ft > 0.97) in preventing the CNS entry of the drug (e.g., nelfinavir). Since we have shown that the rat is an excellent predictor of the verapamil-CsA interaction at the human BBB, we determined the magnitude of drug interaction at the rat BBB between nelfinavir and CsA. Under isoflurane anesthesia, male Sprague-Dawley rats were coadministered IV infusions of nelfinavir and escalating doses of CsA to achieve pseudo steady-state plasma/blood and brain concentrations of both drugs (blood CsA ranged 0-264.9 μM, n = 3-6/group). The percent increase in the brain:blood nelfinavir concentration ratio (determined by LC/MS) was described by the Hill equation with Emax = 6481%, EC50 = 12.3 μM, and γ = 1.6. Then, using these data, as well as in vitro data in LLCPK1 cells expressing the human P-gp, we predicted that CsA (at clinically relevant blood concentration of 1.5 μM) will increase the distribution of nelfinavir into the human brain by 236%. Collectively, our data suggest that clinically significant P-gp based drug interactions at the human BBB are possible for P-gp substrates highly excluded from the brain (ft > 0.97) and should be investigated using noninvasive approaches (e.g., PET).
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Nagaya Y, Nozaki Y, Kobayashi K, Takenaka O, Nakatani Y, Kusano K, Yoshimura T, Kusuhara H. Utility of Cerebrospinal Fluid Drug Concentration as a Surrogate for Unbound Brain Concentration in Nonhuman Primates. Drug Metab Pharmacokinet 2014; 29:419-26. [DOI: 10.2133/dmpk.dmpk-14-rg-026] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Functional Expression of Drug Transporters in Glial Cells. PHARMACOLOGY OF THE BLOOD BRAIN BARRIER: TARGETING CNS DISORDERS 2014; 71:45-111. [DOI: 10.1016/bs.apha.2014.06.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Abstract
Research in the many areas of HIV treatment, eradication and prevention has necessitated measurement of antiretroviral (ARV) concentrations in nontraditional specimen types. To determine the knowledgebase of critical details for accurate bioanalysis, a review of the literature was performed and summarized. Bioanalytical assays for 31 ARVs, including metabolites, were identified in 205 publications measuring various tissues and biofluids. 18 and 30% of tissue or biofluid methods, respectively, analyzed more than one specimen type; 35-37% of the tissue or biofluid methods quantitated more than one ARV. 20 and 76% of tissue or biofluid methods, respectively, were used for the analysis of human specimens. HPLC methods with UV detection predominated, but chronologically MS detection began to surpass. 40% of the assays provided complete intra- and inter-assay validation data, but only 9% of publications provided any stability data with even less for the prevalent ARV in treatments.
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Brandmann M, Nehls U, Dringen R. 8-Hydroxy-efavirenz, the primary metabolite of the antiretroviral drug Efavirenz, stimulates the glycolytic flux in cultured rat astrocytes. Neurochem Res 2013; 38:2524-34. [PMID: 24091996 DOI: 10.1007/s11064-013-1165-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 09/25/2013] [Accepted: 09/26/2013] [Indexed: 12/23/2022]
Abstract
In active antiretroviral therapy antiretroviral drugs are employed for the restoration of a functional immune system in patients suffering from the acquired immunodeficiency syndrome. However, potential adverse effects of such compounds to brain cells are discussed in connection with the development of neurocognitive impairments in patients. To investigate potential effects of antiretroviral drugs on cell viability and the glycolytic flux of brain cells, astrocyte-rich primary cultures were exposed to various antiretroviral compounds, including the non-nucleoside reverse transcriptase inhibitor efavirenz. In a concentration of 10 μM, neither efavirenz nor any of the other investigated antiretroviral compounds acutely compromised the cell viability nor altered glucose consumption or lactate production. In contrast, the primary metabolite of efavirenz, 8-hydroxy-efavirenz, stimulated the glycolytic flux in viable astrocytes in a time- and concentration-dependent manner with half-maximal and maximal effects at concentrations of 5 and 10 μM, respectively. The stimulation of glycolytic flux by 8-hydroxy-efavirenz was not additive to that obtained for astrocytes that were treated with the respiratory chain inhibitor rotenone and was abolished by removal of extracellular 8-hydroxy-efavirenz. In a concentration of 10 μM, 8-hydroxy-efavirenz and efavirenz did not affect mitochondrial respiration, while both compounds lowered in a concentration of 60 μM significantly the oxygen consumption by mitochondria that had been isolated form cultured astrocytes, suggesting that the stimulation of glycolytic flux by 8-hydroxy-efavrienz is not caused by direct inhibition of respiration. The observed alteration of astrocytic glucose metabolism by 8-hydroxy-efavirenz could contribute to the adverse neurological side effects reported for patients that are chronically treated with efavirenz-containing medications.
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Affiliation(s)
- Maria Brandmann
- Centre for Biomolecular Interactions Bremen, University of Bremen, PO. Box 330440, 28334, Bremen, Germany
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Abstract
Severe HIV-associated neurocognitive disorders (HAND), such as HIV-associated dementia, and opportunistic CNS infections are now rare complications of HIV infection due to comprehensive highly active antiretroviral therapy (HAART). By contrast, mild to moderate neurocognitive disorders remain prevalent, despite good viral control in peripheral compartments. HIV infection seems to provoke chronic CNS injury that may evade systemic HAART. Penetration of antiretroviral drugs across the blood-brain barrier might be crucial for the treatment of HAND. This review identifies and evaluates the available clinical evidence on CSF penetration properties of antiretroviral drugs, addressing methodological issues and discussing the clinical relevance of drug concentration assessment. Although a substantial number of studies examined CSF concentrations of antiretroviral drugs, there is a need for adequate, well designed trials to provide more valid drug distribution profiles. Neuropsychological benefits and neurotoxicity of potentially CNS-active drugs require further investigation before penetration characteristics will regularly influence therapeutic strategies and outcome.
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Affiliation(s)
- Christine Eisfeld
- Department of Neurology, University of Münster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany
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Doran AC, Osgood SM, Mancuso JY, Shaffer CL. An Evaluation of Using Rat-Derived Single-Dose Neuropharmacokinetic Parameters to Project Accurately Large Animal Unbound Brain Drug Concentrations. Drug Metab Dispos 2012; 40:2162-73. [DOI: 10.1124/dmd.112.046391] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Michaud V, Bar-Magen T, Turgeon J, Flockhart D, Desta Z, Wainberg MA. The Dual Role of Pharmacogenetics in HIV Treatment: Mutations and Polymorphisms Regulating Antiretroviral Drug Resistance and Disposition. Pharmacol Rev 2012; 64:803-33. [DOI: 10.1124/pr.111.005553] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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33
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Brandmann M, Tulpule K, Schmidt MM, Dringen R. The antiretroviral protease inhibitors indinavir and nelfinavir stimulate Mrp1-mediated GSH export from cultured brain astrocytes. J Neurochem 2011; 120:78-92. [DOI: 10.1111/j.1471-4159.2011.07544.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Adane ED, Liu Z, Xiang TX, Anderson BD, Leggas M. Pharmacokinetic modeling to assess factors affecting the oral bioavailability of the lactone and carboxylate forms of the lipophilic camptothecin analogue AR-67 in rats. Pharm Res 2011; 29:1722-36. [PMID: 22068278 DOI: 10.1007/s11095-011-0617-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 10/25/2011] [Indexed: 11/27/2022]
Abstract
PURPOSE Camptothecin analogues are anticancer drugs effective when dosed in protracted schedules. Such treatment is best suited for oral formulations. AR-67 is a novel lipophilic analogue with potent efficacy in preclinical models. Here we assessed factors that may influence its oral bioavailability in rats. METHODS Plasma pharmacokinetic (PK) studies were conducted following administration of AR-67 lactone or carboxylate doses alone or after pre-dosing with inhibitors of the efflux transporters P-gp and Bcrp. A population PK model that simultaneously fitted to oral and intravenous data was used to estimate the bioavailability (F) and clearance of AR-67. RESULTS An inverse Gaussian function was used as the oral input into the model and provided the best fits. Covariate analysis showed that the bioavailability of the lactone, but not its clearance, was dose dependent. Consistent with this observation, the bioavailability of AR-67 increased when animals were pretreated orally with GF120918 or Zosuquidar. CONCLUSION Absorption of AR-67 is likely affected by solubility of its lactone form and interaction with efflux pumps in the gut. AR-67 appears to be absorbed as the lactone form, most likely due to gastric pH favoring its formation and predominance. F increased at higher doses suggesting saturation of efflux mechanisms.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors
- ATP Binding Cassette Transporter, Subfamily G, Member 2
- ATP-Binding Cassette Transporters/antagonists & inhibitors
- Acridines/administration & dosage
- Acridines/pharmacology
- Administration, Oral
- Animals
- Antineoplastic Agents, Phytogenic/administration & dosage
- Antineoplastic Agents, Phytogenic/blood
- Antineoplastic Agents, Phytogenic/chemistry
- Camptothecin/administration & dosage
- Camptothecin/analogs & derivatives
- Camptothecin/blood
- Carboxylic Acids/administration & dosage
- Carboxylic Acids/blood
- Carboxylic Acids/chemistry
- Female
- Lactones/administration & dosage
- Lactones/blood
- Lactones/chemistry
- Models, Biological
- Rats
- Rats, Sprague-Dawley
- Tetrahydroisoquinolines/administration & dosage
- Tetrahydroisoquinolines/pharmacology
- Topoisomerase I Inhibitors/administration & dosage
- Topoisomerase I Inhibitors/blood
- Topoisomerase I Inhibitors/chemistry
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Affiliation(s)
- Eyob D Adane
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky 40536, USA
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Zeng J, See AP, Aziz K, Thiyagarajan S, Salih T, Gajula RP, Armour M, Phallen J, Terezakis S, Kleinberg L, Redmond K, Hales RK, Salvatori R, Quinones-Hinojosa A, Tran PT, Lim M. Nelfinavir induces radiation sensitization in pituitary adenoma cells. Cancer Biol Ther 2011; 12:657-63. [PMID: 21811091 DOI: 10.4161/cbt.12.7.17172] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Pituitary adenomas with local invasion and high secretory activity remain a therapeutic challenge. The HIV protease inhibitor nelfinavir is a radiosensitizer in multiple tumor models. We tested nelfinavir as a radiosensitizer in pituitary adenoma cells in vitro and in vivo. We examined the effect of nelfinavir with radiation on in vitro cell viability, clonogenic survival, apoptosis, prolactin secretion, cell cycle distribution, and the PI3K-AKT-mTOR pathway. We evaluated tumor growth delay and confirmed nelfinavir's effect on the PI3K-AKT-mTOR pathway in a hind-flank model. Nelfinavir sensitized pituitary adenoma cells to ionizing radiation as shown by viability assays and clonogenic assay with an enhancement ratio of 1.2 (p < 0.05). There is increased apoptotic cell death, as determined by annexin-V expression and cleaved caspase-3 levels. Nelfinavir does not affect prolactin secretion or cell cycle distribution. In vivo, untreated tumors reached 4-fold volume in 12 days, 17 days with nelfinavir treatment, 27 days with radiation 6 Gy, and 41 days with nelfinavir plus radiation (one-way ANOVA p < 0.001). Decreased phospho-S6 on Western blotting in vitro and immunohistochemistry in vivo demonstrated nelfinavir inhibition of the PI3K-AKT-mTOR pathway. Our data suggests a promising combination therapy with nelfinavir plus radiation in pituitary adenomas, which should be investigated in clinical studies.
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Affiliation(s)
- Jing Zeng
- Department of Radiation Oncology and Molecular Radiation Sciences, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA
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Hoekman JD, Ho RJY. Effects of localized hydrophilic mannitol and hydrophobic nelfinavir administration targeted to olfactory epithelium on brain distribution. AAPS PharmSciTech 2011; 12:534-43. [PMID: 21519984 DOI: 10.1208/s12249-011-9614-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 04/04/2011] [Indexed: 11/30/2022] Open
Abstract
Many nasally applied compounds gain access to the brain and the central nervous system (CNS) with varying degree. Direct nose-to-brain access is believed to be achieved through nervous connections which travel from the CNS across the cribriform plate into the olfactory region of the nasal cavity. However, current delivery strategies are not targeted to preferentially deposit drugs to the olfactory at cribriform. Therefore, we have developed a pressurized olfactory delivery (POD) device which consistently and non-invasively deposited a majority of drug to the olfactory region of the nasal cavity in rats. Using both a hydrophobic drug, mannitol (log P = -3.1), and a hydrophobic drug, nelfinavir (log P = 6.0), and POD device, we compared brain and blood levels after nasal deposition primarily on the olfactory region with POD or nose drops which deposited primarily on the respiratory region in rats. POD administration of mannitol in rats provided a 3.6-fold (p < 0.05) increase in cortex-to-blood ratio, compared to respiratory epithelium deposition with nose drop. Administration of nelfinavir provided a 13.6-fold (p < 0.05) advantage in cortex-to-blood ratio with POD administration, compared to nose drops. These results suggest that increasing the fraction of drug deposited on the olfactory region of the nasal cavity will result in increased direct nose-to-brain transport.
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Crouthamel MH, Kelly EJ, Ho RJY. Development and characterization of transgenic mouse models for conditional gene knockout in the blood-brain and blood-CSF barriers. Transgenic Res 2011; 21:113-30. [PMID: 21538071 DOI: 10.1007/s11248-011-9512-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 04/13/2011] [Indexed: 12/11/2022]
Abstract
For many CNS acting drugs, penetration into the central nervous system (CNS) is limited by the blood-CNS-barriers. In an effort to quantitate the role of the protein components that make up the blood-CNS-barriers, we created transgenic mice that allow conditional gene knockout using Cre/loxP technology. We targeted the expression of Cre-recombinase to the choroid plexus (the blood-cerebral spinal fluid barrier) using the lymphotropic papovavirus control region (LPVcr) and to brain endothelium (the blood-brain-barrier) using the proximal promoter region of the human von Willebrand Factor gene (hVWF-f). We verified that LPVcr restricts expression to the choroid plexus in adult mice by using the LPVcr to drive n-LacZ expression in transgenic mice. The LPV-Cre and hVWF-Cre plasmids were then constructed and tested for Cre-recombinase function in vitro, and subsequently used to create transgenic mice. The resulting transgenic mice were characterized for cell-type specific Cre-mediated endonuclease activity by crossing them with transgenic mice containing a loxP-flanked-LacZ/EGFP dual reporter gene Z/EG. The dual Cre-Z/EG transgenic offspring were evaluated for the location of EGFP mRNA expression by reverse transcriptase PCR and for protein expression by immunohistochemistry. Immunohistochemistry for EGFP verified expression in the target cells, and no ectopic expression outside of the expected cell types. The LPV-Cre.0607 transgenic line expressed functional Cre only in the choroid plexus and hVWF-Cre.1304 line in brain endothelium.
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Affiliation(s)
- Matthew H Crouthamel
- Department of Pharmaceutics, University of Washington, Box 357610, Seattle, WA 98195-7610, USA
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Elmeliegy MA, Carcaboso AM, Tagen M, Bai F, Stewart CF. Role of ATP-binding cassette and solute carrier transporters in erlotinib CNS penetration and intracellular accumulation. Clin Cancer Res 2010; 17:89-99. [PMID: 21088257 DOI: 10.1158/1078-0432.ccr-10-1934] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE To study the role of drug transporters in central nervous system (CNS) penetration and cellular accumulation of erlotinib and its metabolite, OSI-420. EXPERIMENTAL DESIGN After oral erlotinib administration to wild-type and ATP-binding cassette (ABC) transporter-knockout mice (Mdr1a/b(-/-), Abcg2(-/-), Mdr1a/b(-/-)Abcg2(-/-), and Abcc4(-/-)), plasma was collected and brain extracellular fluid (ECF) was sampled using intracerebral microdialysis. A pharmacokinetic model was fit to erlotinib and OSI-420 concentration-time data, and brain penetration (P(Brain)) was estimated by the ratio of ECF-to-unbound plasma area under concentration-time curves. Intracellular accumulation of erlotinib was assessed in cells overexpressing human ABC transporters or SLC22A solute carriers. RESULTS P(Brain) in wild-type mice was 0.27 ± 0.11 and 0.07 ± 0.02 (mean ± SD) for erlotinib and OSI-420, respectively. Erlotinib and OSI-420 P(Brain) in Abcg2(-/-) and Mdr1a/b(-/-)Abcg2(-/-) mice were significantly higher than in wild-type mice. Mdr1a/b(-/-) mice showed similar brain ECF penetration as wild-type mice (0.49 ± 0.37 and 0.04 ± 0.02 for erlotinib and OSI-420, respectively). In vitro, erlotinib and OSI-420 accumulation was significantly lower in cells overexpressing breast cancer resistance protein (BCRP) than in control cells. Only OSI-420, not erlotinib, showed lower accumulation in cells overexpressing P-glycoprotein (P-gp) than in control cells. The P-gp/BCRP inhibitor elacridar increased erlotinib and OSI-420 accumulation in BCRP-overexpressing cells. Erlotinib uptake was higher in OAT3- and OCT2-transfected cells than in empty vector control cells. CONCLUSION Abcg2 is the main efflux transporter preventing erlotinib and OSI-420 penetration in mouse brain. Erlotinib and OSI-420 are substrates for SLC22A family members OAT3 and OCT2. Our findings provide a mechanistic basis for erlotinib CNS penetration, cellular uptake, and efflux mechanisms.
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Affiliation(s)
- Mohamed A Elmeliegy
- Department of Pharmaceutical Sciences, St Jude Children's Research Hospital, University of Tennessee Health Science Center, Memphis, Tennessee 38105, USA
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Crouthamel MH, Wu D, Yang Z, Ho RJY. A novel MDR1 GT1292-3TG (Cys431Leu) genetic variation and its effect on P-glycoprotein biologic functions. AAPS JOURNAL 2010; 12:548-55. [PMID: 20623213 DOI: 10.1208/s12248-010-9216-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Accepted: 06/18/2010] [Indexed: 01/08/2023]
Abstract
P-glycoprotein (P-gp) is a membrane-bound transporter protein that is encoded by the human multidrug resistance gene MDR1 (ABCB1). P-gp recognizes a wide range of xenobiotics, is pivotal in mediating cancer drug resistance, and plays an important role in limiting drug penetration across the blood-brain barrier. MDR1 genetic variation can lead to changes in P-gp function and may have implications on drug pharmacokinetics. We have identified a novel MDR1 (GT1292-3TG) (Cys431Leu) genetic variation through systematic profiling of subjects with leukemia. The cellular and transport function of this variation was investigated with recombinant human embryonic kidney cells expressing MDR1. Compared with the wild type, MDR1 (GT1292-3TG) recombinant cells exhibited a lower drug resistance phenotype for a panel of chemotherapeutic agents. When compared with wild type, MDR1 (GT1292-3TG) recombinant cells exposed exhibited a 75% decrease in IC₅₀ for doxorubicin (162.6 ± 17.4 to 37.9 ± 2.6 nM) and a 50% decrease in IC(50) for paclitaxel (155.7 ± 27.5 to 87.7 ± 9.2 nM), vinblastine (128.0 ± 15.9 to 65.9 ± 5.1 nM), and vincristine (593.7 ± 61.8 to 307.3 ± 17.0 nM). The effects of the Cys431Leu variation, due to MDR1 (GT1292-3TG) nucleotide transition, on P-gp-dependent intracellular substrate accumulation appeared to be substrate dependent where doxorubicin, vinblastine, and paclitaxel exhibit an increased accumulation (p < 0.05), while verapamil and Hoechst33342 exhibit a decreased intracellular concentration compared with wild type (p < 0.05). Collectively, these data suggest MDR1 (GT1292-3TG) variation of P-gp may reduce drug resistance and that subjects with this genotype undergoing chemotherapy with drugs that are transported by P-gp could potentially be more responsive to therapy than those with MDR1 wild-type genotype.
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Weiss J, Haefeli WE. Impact of ATP-binding cassette transporters on human immunodeficiency virus therapy. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 280:219-79. [PMID: 20797684 DOI: 10.1016/s1937-6448(10)80005-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Even though potent antiretrovirals are available against human immunodeficiency virus (HIV)-1 infection, therapy fails in a significant fraction of patients. Among the most relevant reasons for treatment failure are drug toxicity and side effects, but also the development of viral resistance towards the drugs applied. Efflux by ATP-binding cassette (ABC-) transporters represents one major mechanism influencing the pharmacokinetics of antiretroviral drugs and particularly their distribution, thus modifiying the concentration within the infected cells, that is, at the site of action. Moreover, drug-drug interactions may occur at the level of these transporters and modulate their activity or expression thus influencing the efficacy and toxicity of the substrate drugs. This review summarizes current knowledge on the interaction of antiretrovirals used for HIV-1 therapy with ABC-transporters and highlights the impact of ABC-transporters for cellular resistance and therapeutic success. Moreover, the suitability of different cell models for studying the interaction of antiretrovirals with ABC-transporters is discussed.
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Affiliation(s)
- Johanna Weiss
- Department of Clinical Pharmacology and Pharmacoepidemiology, University of Heidelberg, Heidelberg, Germany
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The complexities of antiretroviral drug-drug interactions: role of ABC and SLC transporters. Trends Pharmacol Sci 2009; 31:22-35. [PMID: 20004485 DOI: 10.1016/j.tips.2009.10.001] [Citation(s) in RCA: 181] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Revised: 09/30/2009] [Accepted: 10/01/2009] [Indexed: 12/15/2022]
Abstract
Treatment of human immunodeficiency virus (HIV) infection involves a combination of several antiviral agents belonging to different pharmacological classes. This combination is referred to as highly active antiretroviral therapy (HAART). This treatment has proved to be very effective in suppressing HIV replication, but antiretroviral drugs have complex pharmacokinetic properties involving extensive drug metabolism and transport by membrane-associated drug carriers. Combination drug therapy often introduces complex drug-drug interactions that can result in toxic or sub-therapeutic drug concentrations, compromising treatment. This review focuses on the role of ATP-binding cassette (ABC) membrane-associated efflux transporters and solute carrier (SLC) uptake transporters in antiretroviral drug disposition, and identifies clinically important antiretroviral drug-drug interactions associated with changes in drug transport.
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Shen J, Carcaboso AM, Hubbard KE, Tagen M, Wynn HG, Panetta JC, Waters CM, Elmeliegy MA, Stewart CF. Compartment-specific roles of ATP-binding cassette transporters define differential topotecan distribution in brain parenchyma and cerebrospinal fluid. Cancer Res 2009; 69:5885-92. [PMID: 19567673 PMCID: PMC2729173 DOI: 10.1158/0008-5472.can-09-0700] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Topotecan is a substrate of the ATP-binding cassette transporters P-glycoprotein (P-gp/MDR1) and breast cancer resistance protein (BCRP). To define the role of these transporters in topotecan penetration into the ventricular cerebrospinal fluid (vCSF) and brain parenchymal extracellular fluid (ECF) compartments, we performed intracerebral microdialysis on transporter-deficient mice after an intravenous dose of topotecan (4 mg/kg). vCSF penetration of unbound topotecan lactone was measured as the ratio of vCSF-to-plasma area under the concentration-time curves. The mean +/- SD ratios for wild-type, Mdr1a/b(-/-), Bcrp1(-/-), and Mdr1a/b(-/-)Bcrp1(-/-) mice were 3.07 +/- 0.09, 2.57 +/- 0.17, 1.63 +/- 0.12, and 0.86 +/- 0.05, respectively. In contrast, the ECF-to-plasma ratios for wild-type, Bcrp1(-/-), and Mdr1a/b(-/-)Bcrp1(-/-) mice were 0.36 +/- 0.06, 0.42 +/- 0.06, and 0.88 +/- 0.07. Topotecan lactone was below detectable limits in the ECF of Mdr1a/b(-/-) mice. When gefitinib (200 mg/kg) was preadministered to inhibit Bcrp1 and P-gp, the vCSF-to-plasma ratio decreased to 1.29 +/- 0.09 in wild-type mice and increased to 1.13 +/- 0.13 in Mdr1a/b(-/-)Bcrp1(-/-) mice, whereas the ECF-to-plasma ratio increased to 0.74 +/- 0.14 in wild-type and 1.07 +/- 0.03 in Mdr1a/b(-/-)Bcrp1(-/-) mice. Preferential active transport of topotecan lactone over topotecan carboxylate was shown in vivo by vCSF lactone-to-carboxylate area under the curve ratios for wild-type, Mdr1a/b(-/-), Bcrp1(-/-), and Mdr1a/b(-/-)Bcrp1(-/-) mice of 5.69 +/- 0.83, 3.85 +/- 0.64, 3.61 +/- 0.46, and 0.78 +/- 0.19, respectively. Our results suggest that Bcrp1 and P-gp transport topotecan into vCSF and out of brain parenchyma through the blood-brain barrier. These findings may help to improve pharmacologic strategies to treat brain tumors.
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Affiliation(s)
- Jun Shen
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, University of Tennessee, Memphis
- University of Tennessee Health Science Center, University of Tennessee, Memphis
| | - Angel M. Carcaboso
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, University of Tennessee, Memphis
| | - K. Elaine Hubbard
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, University of Tennessee, Memphis
| | - Michael Tagen
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, University of Tennessee, Memphis
| | - Henry G. Wynn
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, University of Tennessee, Memphis
| | - John C. Panetta
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, University of Tennessee, Memphis
| | | | - Mohamed A. Elmeliegy
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, University of Tennessee, Memphis
- University of Tennessee Health Science Center, University of Tennessee, Memphis
| | - Clinton F. Stewart
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, University of Tennessee, Memphis
- University of Tennessee Health Science Center, University of Tennessee, Memphis
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Eyal S, Hsiao P, Unadkat JD. Drug interactions at the blood-brain barrier: fact or fantasy? Pharmacol Ther 2009; 123:80-104. [PMID: 19393264 DOI: 10.1016/j.pharmthera.2009.03.017] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Accepted: 03/20/2009] [Indexed: 12/24/2022]
Abstract
There is considerable interest in the therapeutic and adverse outcomes of drug interactions at the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB). These include altered efficacy of drugs used in the treatment of CNS disorders, such as AIDS dementia and malignant tumors, and enhanced neurotoxicity of drugs that normally penetrate poorly into the brain. BBB- and BCSFB-mediated interactions are possible because these interfaces are not only passive anatomical barriers, but are also dynamic in that they express a variety of influx and efflux transporters and drug metabolizing enzymes. Based on studies in rodents, it has been widely postulated that efflux transporters play an important role at the human BBB in terms of drug delivery. Furthermore, it is assumed that chemical inhibition of transporters or their genetic ablation in rodents is predictive of the magnitude of interaction to be expected at the human BBB. However, studies in humans challenge this well-established paradigm and claim that such drug interactions will be lesser in magnitude but yet may be clinically significant. This review focuses on current known mechanisms of drug interactions at the blood-brain and blood-CSF barriers and the potential impact of such interactions in humans. We also explore whether such drug interactions can be predicted from preclinical studies. Defining the mechanisms and the impact of drug-drug interactions at the BBB is important for improving efficacy of drugs used in the treatment of CNS disorders while minimizing their toxicity as well as minimizing neurotoxicity of non-CNS drugs.
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Affiliation(s)
- Sara Eyal
- Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington 98195, USA
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Shaik N, Pan G, Elmquist WF. Interactions of pluronic block copolymers on P-gp efflux activity: experience with HIV-1 protease inhibitors. J Pharm Sci 2009; 97:5421-33. [PMID: 18393290 DOI: 10.1002/jps.21372] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The objective was to examine the influence of Pluronic block-copolymers on the interaction between the drug efflux transporter, P-glycoprotein and HIV-1 protease inhibitors (PIs). The ATPase assay determined the effect of various Pluronics on PI-stimulated P-gp ATPase activity. Cellular accumulation studies were conducted using MDCKII and LLC-PK1 cells transfected with human MDR1 to assess Pluronic modulation of PI efflux. Pluronic P85 inhibited both basal and nelfinavir-stimulated P-gp ATPase activity, while Pluronic F127 had no effect. In cell accumulation studies, Pluronic P85 restored the accumulation of nelfinavir in MDCKII-MDR1 cells while Pluronic F127 and F88 had no effect. Pluronic P85 increased saquinavir accumulation in wild-type and MDR1-transfected cells in both the MDCKII and LLC-PK1 cell models, suggesting inhibition of multiple transporters, including MRPs. In conclusion, this study provides evidence that a block-copolymer, Pluronic P85, effectively inhibits the interaction of P-gp with nelfinavir and saquinavir. These data indicate that effective inhibition of HIV-1 PI efflux by Pluronic P85 may influence the distribution of antiretroviral agents to sites protected by efflux mechanisms, such as the blood-brain barrier, and possibly increase the brain exposure of these drugs resulting in suppression of viral replication and reduction in the incidence of drug resistant mutants.
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Affiliation(s)
- Naveed Shaik
- Department of Pharmaceutics, College of Pharmacy, University of Minnesota, 308 Harvard St. SE, Room 9-125d, Weaver-Densford Hall, Minneapolis, Minnesota 55455, USA
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Ayrton A, Morgan P. Role of transport proteins in drug discovery and development: a pharmaceutical perspective. Xenobiotica 2008; 38:676-708. [DOI: 10.1080/00498250801923855] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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TAT-conjugated nanoparticles for the CNS delivery of anti-HIV drugs. Biomaterials 2008; 29:4429-38. [PMID: 18760470 DOI: 10.1016/j.biomaterials.2008.08.004] [Citation(s) in RCA: 233] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2008] [Accepted: 08/04/2008] [Indexed: 11/22/2022]
Abstract
We have shown that nanoparticles (NPs) conjugated to trans-activating transcriptor (TAT) peptide bypass the efflux action of P-glycoprotein and increase the transport of the encapsulated ritonavir, a protease inhibitor (PI), across the blood-brain-barrier (BBB) to the central nervous system (CNS). A steady increase in the drug parenchyma/capillary ratio over time without disrupting the BBB integrity suggests that TAT-conjugated NPs are first immobilized in the brain vasculature prior to their transport into parenchyma. Localization of NPs in the brain parenchyma was further confirmed with histological analysis of the brain sections. The brain drug level with conjugated NPs was 800-fold higher than that with drug in solution at two weeks. Drug clearance was seen within four weeks. In conclusion, TAT-conjugated NPs enhanced the CNS bioavailability of the encapsulated PI and maintained therapeutic drug levels in the brain for a sustained period that could be effective in reducing the viral load in the CNS, which acts as a reservoir for the replicating HIV-1 virus.
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Oosterhuis B, Vukman K, Vági E, Glavinas H, Jablonkai I, Krajcsi P. Specific interactions of chloroacetanilide herbicides with human ABC transporter proteins. Toxicology 2008; 248:45-51. [PMID: 18433974 DOI: 10.1016/j.tox.2008.03.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Revised: 03/07/2008] [Accepted: 03/07/2008] [Indexed: 11/17/2022]
Abstract
Chloroacetanilide herbicides are among the most commonly used herbicides in agriculture. Several studies have demonstrated a number of them to be carcinogenic. ATP binding cassette (ABC) transporters are efflux pumps expressed in cell membranes, which form an important wall of defense against xenobiotics from different sources. We tested the interaction of the herbicides acetochlor, alachlor, dimetachlor, metazachlor, metolachlor, propachlor and prynachlor with human multidrug resistance transporters MDR1, MRP1, MRP2 and BCRP. A number of metabolites were studied for interaction with MRP1, MRP2 and MRP3. Transporter interactions were studied by measuring ATPase activity, inhibition of fluorescent dye efflux and vesicular transport. Also inhibition of MDR1 was monitored by measuring digoxin transport on Caco-2 monolayers and paclitaxel toxicity on K562-MDR cells. Acetochlor, alachlor, metolachlor and metazachlor showed specific interactions with MDR1. Digoxin permeability and paclitaxel cytotoxicity studies revealed that these herbicides are potent inhibitors of MDR1 that can modulate drug absorption and cause chemosensitization of cells. MRP1 was demonstrated to transport an important intermediate of the acetochlor detoxification pathway. Several specific interactions were shown when studying the interaction of chloroacetanilides with human transporter proteins. This study suggests an important role for transporter proteins in hazard prediction of agrochemicals and demonstrates how transporter interactions can be easily detected using in vitro screening methods.
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