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Schmidt S, Hoffmann H, Garbe LA, Harrer A, Steiner M, Himly M, Schneider RJ. Re-assessment of monoclonal antibodies against diclofenac for their application in the analysis of environmental waters. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2024; 16:3349-3363. [PMID: 38742423 PMCID: PMC11138808 DOI: 10.1039/d3ay01333b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 05/07/2024] [Indexed: 05/16/2024]
Abstract
The non-steroidal anti-inflammatory drug (NSAID) diclofenac (DCF) is an important environmental contaminant occurring in surface waters all over the world, because, after excretion, it is not adequately removed from wastewater in sewage treatment plants. To be able to monitor this pollutant, highly efficient analytical methods are needed, including immunoassays. In a medical research project, monoclonal antibodies against diclofenac and its metabolites had been produced. Based on this monoclonal anti-DCF antibody, a new indirect competitive enzyme-linked immunosorbent assay (ELISA) was developed and applied for environmental samples. The introduction of a spacer between diclofenac and the carrier protein in the coating conjugate led to higher sensitivity. With a test midpoint of 3 μg L-1 and a measurement range of 1-30 μg L-1, the system is not sensitive enough for direct analysis of surface water. However, this assay is quite robust against matrix influences and can be used for wastewater. Without adjustment of the calibration, organic solvents up to 5%, natural organic matter (NOM) up to 10 mg L-1, humic acids up to 2.5 mg L-1, and salt concentrations up to 6 g L-1 NaCl and 75 mg L-1 CaCl2 are tolerated. The antibody is also stable in a pH range from 3 to 12. Cross-reactivity (CR) of 1% or less was determined for the metabolites 4'-hydroxydiclofenac (4'-OH-DCF), 5-hydroxydiclofenac (5-OH-DCF), DCF lactam, and other NSAIDs. Relevant cross-reactivity occurred only with an amide derivative of DCF, 6-aminohexanoic acid (DCF-Ahx), aceclofenac (ACF) and DCF methyl ester (DCF-Me) with 150%, 61% and 44%, respectively. These substances, however, have not been found in samples. Only DCF-acyl glucuronide with a cross-reactivity of 57% is of some relevance. For the first time, photodegradation products were tested for cross-reactivity. With the ELISA based on this antibody, water samples were analysed. In sewage treatment plant effluents, concentrations in the range of 1.9-5.2 μg L-1 were determined directly, with recoveries compared to HPLC-MS/MS averaging 136%. Concentrations in lakes ranged from 3 to 4.4 ng L-1 and were, after pre-concentration, determined with an average recovery of 100%.
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Affiliation(s)
- Stephan Schmidt
- Department of Analytical Chemistry, Reference Materials, BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Str. 11, 12489 Berlin, Germany.
- Technische Universität Berlin, Straße des 17. Juni 135, D-10623 Berlin, Germany
| | - Holger Hoffmann
- Department of Analytical Chemistry, Reference Materials, BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Str. 11, 12489 Berlin, Germany.
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, D-12489 Berlin, Germany
| | - Leif-Alexander Garbe
- Hochschule Neubrandenburg, Fachbereich Agrarwirtschaft und Lebensmittelwissenschaften, D-17033 Neubrandenburg, Germany
| | - Andrea Harrer
- Department of Biosciences and Medical Biology, Division of Allergy and Immunology, Paris Lodron University of Salzburg, A-5020 Salzburg, Austria
| | - Markus Steiner
- Department of Biosciences and Medical Biology, Division of Allergy and Immunology, Paris Lodron University of Salzburg, A-5020 Salzburg, Austria
| | - Martin Himly
- Department of Biosciences and Medical Biology, Division of Allergy and Immunology, Paris Lodron University of Salzburg, A-5020 Salzburg, Austria
| | - Rudolf J Schneider
- Department of Analytical Chemistry, Reference Materials, BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Str. 11, 12489 Berlin, Germany.
- Technische Universität Berlin, Straße des 17. Juni 135, D-10623 Berlin, Germany
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Gerges SH, El-Kadi AOS. Sexual Dimorphism in the Expression of Cytochrome P450 Enzymes in Rat Heart, Liver, Kidney, Lung, Brain, and Small Intestine. Drug Metab Dispos 2023; 51:81-94. [PMID: 36116791 DOI: 10.1124/dmd.122.000915] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 07/26/2022] [Accepted: 07/28/2022] [Indexed: 12/30/2022] Open
Abstract
Cytochrome P450 (P450) enzymes are monooxygenases that are expressed hepatically and extrahepatically and play an essential role in xenobiotic metabolism. Substantial scientific evidence indicates sex-specific differences between males and females in disease patterns and drug responses, which could be attributed, even partly, to differences in the expression and/or activity levels of P450 enzymes in different organs. In this study, we compared the mRNA and protein expression of P450 enzymes in different organs of male and female Sprague-Dawley rats by real-time polymerase chain reaction and western blot techniques. We found significant sex- and organ-specific differences in several enzymes. Hepatic Cyp2c11, Cyp2c13, and Cyp4a2 showed male-specific expression, whereas Cyp2c12 showed female-specific expression. Cyp2e1 and Cyp4f enzymes demonstrated higher expression in the female heart and kidneys compared with males; however, they showed no significant sexual dimorphism in the liver. Male rats showed higher hepatic and renal Cyp1b1 levels. All assessed enzymes were found in the liver, but some were not expressed in other organs. At the protein expression level, CYP1A2, CYP3A, and CYP4A1 demonstrated higher expression levels in the females in several organs, including the liver. Elucidating sex-specific differences in P450 enzyme levels could help better understand differences in disease pathogeneses and drug responses between males and females and thus improve treatment strategies. SIGNIFICANCE STATEMENT: This study characterized the differences in the mRNA and protein expression levels of different cytochrome P450 (P450) enzymes between male and female rats in the heart, liver, lung, kidney, brain, and small intestine. It demonstrated unique sex-specific differences in the different organs. This study is considered a big step towards elucidating sex-specific differences in P450 enzyme levels, which is largely important for achieving a better understanding of the differences between males and females in the disease's processes and treatment outcomes.
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Affiliation(s)
- Samar H Gerges
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Ayman O S El-Kadi
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
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Li Y, Qin J, Wu H, Xu Y, Zhang L, Su K, Cui Y, Wang H. In vitro inhibitory effect of lysionotin on the activity of cytochrome P450 enzymes. PHARMACEUTICAL BIOLOGY 2020; 58:695-700. [PMID: 32673137 PMCID: PMC7470033 DOI: 10.1080/13880209.2020.1787468] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
CONTEXT Lysionotin, a major extraction of Lysionotus pauciflorus Maxim (Gesneriaceae), has a variety of pharmacological properties commonly used in the treatment of lung disease. A study of lysionotin on the activity of human liver cytochrome P450 (CYP) enzymes can provide guidance on the clinical application of lysionotin. OBJECTIVE This study investigated the interaction between lysionotin and CYPs. MATERIAL AND METHOD The effects of 100 μM lysionotin on eight human liver CYP isoforms (i.e., 1A2, 3A4, 2A6, 2E1, 2D6, 2C9, 2C19 and 2C8) were investigated in vitro using human liver microsomes (HLMs) with specific inhibitor as positive control and untreated HLMs as control. Meanwhile, the enzyme kinetic parameters were calculated. A time-dependent study was performed with a time interval of 5 min in 30 min. RESULTS Lysionotin was found to inhibit the activity of CYP3A4, 2C19, and 2C8, with IC50 values of 13.85, 24.95, and 30.05 μM, respectively. The inhibition of CYP3A4 was performed in a non-competitive manner with the Ki value of 6.83 μM, while the inhibition of CYP2C19 and 2C8 was performed in a competitive manner with Ki values of 12.41 and 14.51 μM. Moreover, it was found that the inhibition of CYP3A4 was time-dependent with K I/K inact value of 6.618/0.048 min/μM. Discussion and conclusions: The in vitro inhibitory effect of lysionotin on the activity of CYP3A4, 2C19, and 2C8 indicated potential drug interactions between lysionotin and drugs metabolised by CYP3A4, 2C19, and 2C8. Further in vivo experiments are needed to assess the potential interactions.
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Affiliation(s)
- Yang Li
- Department of Neurology, The Affiliated Hospital of Qingdao University, Qingdao, China
- Department of Neurology, Zibo No. 4 People’s Hospital, Zibo, China
| | - Jing Qin
- Department of Laboratory, Yidu Central Hospital of Weifang, Weifang, China
| | - Hong Wu
- Department of Oncology, Binzhou Medical University Hospital, Binzhou, China
| | - Yongmei Xu
- Department of Cardiology, Shanxian Central Hospital, Heze, China
| | - Li Zhang
- Department of Pharmacy, Shanxian Central Hospital, Heze, China
| | - Keren Su
- Department of Pharmacy, Shanxian Central Hospital, Heze, China
| | - Ying Cui
- Department of Hematology and Nephrology, Shanxian Central Hospital, Heze, China
- CONTACT Ying Cui Department of Hematology and Nephrology, Shanxian Central Hospital, No. 1, Wenhua Road, Heze274300, Shandong, China
| | - Haiping Wang
- Department of Neurology, The Affiliated Hospital of Qingdao University, Qingdao, China
- Haiping Wang Department of Neurology, The Affiliated Hospital of Qingdao University, No. 16, Jiangsu Road, Qingdao266000, Shandong, China
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Selvaraj S, Oh JH, Borlak J. An adverse outcome pathway for immune-mediated and allergic hepatitis: a case study with the NSAID diclofenac. Arch Toxicol 2020; 94:2733-2748. [PMID: 32372211 PMCID: PMC7395045 DOI: 10.1007/s00204-020-02767-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 04/22/2020] [Indexed: 12/26/2022]
Abstract
Many drugs have the potential to cause drug-induced liver injury (DILI); however, underlying mechanisms are diverse. The concept of adverse outcome pathways (AOPs) has become instrumental for risk assessment of drug class effects. We report AOPs specific for immune-mediated and drug hypersensitivity/allergic hepatitis by considering genomic, histo- and clinical pathology data of mice and dogs treated with diclofenac. The findings are relevant for other NSAIDs and drugs undergoing iminoquinone and quinone reactive metabolite formation. We define reactive metabolites catalyzed by CYP monooxygenase and myeloperoxidases of neutrophils and Kupffer cells as well as acyl glucuronides produced by uridine diphosphoglucuronosyl transferase as molecular initiating events (MIE). The reactive metabolites bind to proteins and act as neo-antigen and involve antigen-presenting cells to elicit B- and T-cell responses. Given the diverse immune systems between mice and dogs, six different key events (KEs) at the cellular and up to four KEs at the organ level are defined with mechanistic plausibility for the onset and progression of liver inflammation. With mice, cellular stress response, interferon gamma-, adipocytokine- and chemokine signaling provided a rationale for the AOP of immune-mediated hepatitis. With dogs, an erroneous programming of the innate and adaptive immune response resulted in mast cell activation; their infiltration into liver parenchyma and the shift to M2-polarized Kupffer cells signify allergic hepatitis and the occurrence of granulomas of the liver. Taken together, diclofenac induces divergent immune responses among two important preclinical animal species, and the injury pattern seen among clinical cases confirms the relevance of the developed AOP for immune-mediated hepatitis.
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Affiliation(s)
- Saravanakumar Selvaraj
- Centre for Pharmacology and Toxicology, Hannover Medical School, 30625, Hannover, Germany
| | - Jung-Hwa Oh
- Centre for Pharmacology and Toxicology, Hannover Medical School, 30625, Hannover, Germany.,Department of Predictive Toxicology, Korea Institute of Toxicology, Gajeong-ro, Yuseong, Daejeon, 34114, Republic of Korea
| | - Jürgen Borlak
- Centre for Pharmacology and Toxicology, Hannover Medical School, 30625, Hannover, Germany.
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Fan X, Ding X, Zhang QY. Hepatic and intestinal biotransformation gene expression and drug disposition in a dextran sulfate sodium-induced colitis mouse model. Acta Pharm Sin B 2020; 10:123-135. [PMID: 31993311 PMCID: PMC6976992 DOI: 10.1016/j.apsb.2019.12.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 10/31/2019] [Accepted: 11/07/2019] [Indexed: 12/27/2022] Open
Abstract
We examined the impact of gut inflammation on the expression of cytochrome P450 (P450) and other biotransformation genes in male mice using a dextran sulfate sodium (DSS)-induced colitis model. Several P450 isoforms, including CYP1A, CYP2B, CYP2C, and CYP3A, were down-regulated, accompanied by decreases in microsomal metabolism of diclofenac and nifedipine, in the liver and small intestine. The impact of the colitis on in vivo clearance of oral drugs varied for four different drugs tested: a small decrease for nifedipine, a relatively large decrease for lovastatin, but no change for pravastatin, and a large decrease in the absorption of cyclosporine A. To further assess the scope of influence of gut inflammation on gene expression, we performed genome-wide expression analysis using RNA-seq, which showed down-regulation of many CYPs, non-CYP phase-I enzymes, phase-II enzymes and transporters, and up-regulation of many other members of these gene families, in both liver and intestine of adult C57BL/6 mice, by DSS-induced colitis. Overall, our results indicate that gut inflammation suppresses the expression of many P450s and other biotransformation genes in the intestine and liver, and alters the pharmacokinetics for some but not all drugs, potentially affecting therapeutic efficacy or causing adverse effects in a drug-specific fashion.
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Flampouri E, Imar S, OConnell K, Singh B. Spheroid-3D and Monolayer-2D Intestinal Electrochemical Biosensor for Toxicity/Viability Testing: Applications in Drug Screening, Food Safety, and Environmental Pollutant Analysis. ACS Sens 2019; 4:660-669. [PMID: 30698007 DOI: 10.1021/acssensors.8b01490] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The rise of three-dimensional cell culture systems that provide in vivo-like environments for pharmaco-toxicological models has prompted the need for simple and robust viability assays suitable for complex cell architectural structures. This study addresses that challenge with the development of an in vitro enzyme based electrochemical sensor for viability/cytotoxicity assessment of two-dimensional (2D) monolayer and three-dimensional (3D) spheroid culture formats. The biosensor measures the cell viability/toxicity via electrochemical monitoring of the enzymatic activity of nonspecific esterases of viable cells, through the hydrolysis of 1-naphthyl acetate to 1-naphthol. The proposed sensor demonstrated strong correlation ( r = 0.979) with viable cell numbers. Furthermore, the model intestinal toxicants diclofenac (DFC, pharmaceutical), okadaic acid (OA, food-safety), and mancozeb (MZB, environmental) were used for the functional evaluation of the proposed sensor using 2D and 3D culture formats. Sensor performance showed high consistency with conventional cell viability/cytotoxicity assays (MTT/CFDA-AM) for all toxicants, with the sensor IC50 values matching the relevant viability LC50 values at the 95% confidence interval range for 2D (DCF: 1.19-1.26 mM, MZB: 10.28-14.18 μM, OA: 40.91-77.13 nM) and 3D culture formats (DCF: 1.02-4.78 mM, MZB: 11.26-15.16 μM, OA: 162.09-179.67 nM). The presented results demonstrate the feasibility of the proposed sensor as a robust endpoint screening tool for both 2D and 3D cytotoxicity assessment.
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Affiliation(s)
- Evangelia Flampouri
- MiCRA Biodiagnostics Technology Gateway, Technological University Dublin (TU Dublin - Tallaght Campus), Tallaght, Dublin 24, D24 FKT9, Ireland
| | - Shahzad Imar
- MiCRA Biodiagnostics Technology Gateway, Technological University Dublin (TU Dublin - Tallaght Campus), Tallaght, Dublin 24, D24 FKT9, Ireland
| | - Kieran OConnell
- MiCRA Biodiagnostics Technology Gateway, Technological University Dublin (TU Dublin - Tallaght Campus), Tallaght, Dublin 24, D24 FKT9, Ireland
- Hothouse, Technological University Dublin, (TU Dublin − City Campus), Aungier Street, Dublin 2, D02 HW71, Ireland
| | - Baljit Singh
- MiCRA Biodiagnostics Technology Gateway, Technological University Dublin (TU Dublin - Tallaght Campus), Tallaght, Dublin 24, D24 FKT9, Ireland
- Hothouse, Technological University Dublin, (TU Dublin − City Campus), Aungier Street, Dublin 2, D02 HW71, Ireland
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Schmidt S, Hoffmann H, Garbe LA, Schneider RJ. Liquid chromatography-tandem mass spectrometry detection of diclofenac and related compounds in water samples. J Chromatogr A 2018; 1538:112-116. [PMID: 29397981 DOI: 10.1016/j.chroma.2018.01.037] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Revised: 12/19/2017] [Accepted: 01/17/2018] [Indexed: 10/18/2022]
Abstract
A frequently studied environmental contaminant is the active substance diclofenac, which is removed insufficiently in sewage treatment plants. Since its inclusion in the watch list of the EU Water Framework Directive, the concentrations in surface waters will be determined throughout Europe. For this, still, more precise analytical methods are needed. As a reference, HPLC-MS is frequently employed. One of the major metabolites is 4'-hydroxydiclofenac (4'-OH-DCF). Also, diclofenac lactam is important for assessing degradation and transformation. Aceclofenac (ACF), the glycolic acid ester of diclofenac is used as a drug, too, and could potentially be cleaved to yield diclofenac again. In various sewage treatment plant influent samples, diclofenac, 4'-OH-DCF, DCF lactam and ACF could be determined with detection limits of 3 μg/L, 0.2 μg/L, 0.17 μg/L and 10 ng/L, respectively.
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Affiliation(s)
- Stephan Schmidt
- BAM Federal Institute for Materials Research and Testing, Department of Analytical Chemistry; Reference Materials, Richard-Willstätter-Str. 11, 12489 Berlin, Germany; Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Holger Hoffmann
- BAM Federal Institute for Materials Research and Testing, Department of Analytical Chemistry; Reference Materials, Richard-Willstätter-Str. 11, 12489 Berlin, Germany; Humboldt-Universität zu Berlin, Department of Chemistry, Brook-Taylor-Str. 2, 12489 Berlin, Germany
| | - Leif-Alexander Garbe
- Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany; Hochschule Neubrandenburg, Department of Agroscience and Food Science, Brodaer Str. 2, 17033 Neubrandenburg, Germany
| | - Rudolf J Schneider
- BAM Federal Institute for Materials Research and Testing, Department of Analytical Chemistry; Reference Materials, Richard-Willstätter-Str. 11, 12489 Berlin, Germany; Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany.
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Li M, de Graaf IA, de Jager MH, Groothuis GM. P-gp activity and inhibition in the different regions of human intestineex vivo. Biopharm Drug Dispos 2016; 38:127-138. [DOI: 10.1002/bdd.2047] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 09/21/2016] [Accepted: 10/14/2016] [Indexed: 01/03/2023]
Affiliation(s)
- Ming Li
- Department of Pharmacokinetics, Toxicology & Targeting; Groningen Research Institute of Pharmacy, University of Groningen; Antonius Deusinglaan 1, 9713 AV Groningen the Netherlands
| | - Inge A.M. de Graaf
- Department of Pharmacokinetics, Toxicology & Targeting; Groningen Research Institute of Pharmacy, University of Groningen; Antonius Deusinglaan 1, 9713 AV Groningen the Netherlands
| | - Marina H. de Jager
- Department of Pharmacokinetics, Toxicology & Targeting; Groningen Research Institute of Pharmacy, University of Groningen; Antonius Deusinglaan 1, 9713 AV Groningen the Netherlands
| | - Geny M.M. Groothuis
- Department of Pharmacokinetics, Toxicology & Targeting; Groningen Research Institute of Pharmacy, University of Groningen; Antonius Deusinglaan 1, 9713 AV Groningen the Netherlands
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Differential sensitivity of metabolically competent and non-competent HepaRG cells to apoptosis induced by diclofenac combined or not with TNF-α. Toxicol Lett 2016; 258:71-86. [DOI: 10.1016/j.toxlet.2016.06.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 05/24/2016] [Accepted: 06/10/2016] [Indexed: 01/20/2023]
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Xie F, Ding X, Zhang QY. An update on the role of intestinal cytochrome P450 enzymes in drug disposition. Acta Pharm Sin B 2016; 6:374-383. [PMID: 27709006 PMCID: PMC5045550 DOI: 10.1016/j.apsb.2016.07.012] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 07/12/2016] [Accepted: 07/14/2016] [Indexed: 12/05/2022] Open
Abstract
Oral administration is the most commonly used route for drug treatment. Intestinal cytochrome P450 (CYP)-mediated metabolism can eliminate a large proportion of some orally administered drugs before they reach systemic circulation, while leaving the passage of other drugs unimpeded. A better understanding of the ability of intestinal P450 enzymes to metabolize various clinical drugs in both humans and preclinical animal species, including the identification of the CYP enzymes expressed, their regulation, and the relative importance of intestinal metabolism compared to hepatic metabolism, is important for improving bioavailability of current drugs and new drugs in development. Here, we briefly review the expression of drug-metabolizing P450 enzymes in the small intestine of humans and several preclinical animal species, and provide an update of the various factors or events that regulate intestinal P450 expression, including a cross talk between the liver and the intestine. We further compare various clinical and preclinical approaches for assessing the impact of intestinal drug metabolism on bioavailability, and discuss the utility of the intestinal epithelium–specific NADPH-cytochrome P450 reductase-null (IECN) mouse as a useful model for studying in vivo roles of intestinal P450 in the disposition of orally administered drugs.
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Simulation of interindividual differences in inactivation of reactive para -benzoquinone imine metabolites of diclofenac by glutathione S -transferases in human liver cytosol. Toxicol Lett 2016; 255:52-62. [DOI: 10.1016/j.toxlet.2016.05.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 05/11/2016] [Accepted: 05/12/2016] [Indexed: 01/11/2023]
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Characterization of cytochrome P450 isoforms involved in sequential two-step bioactivation of diclofenac to reactive p-benzoquinone imines. Toxicol Lett 2016; 253:46-54. [PMID: 27130197 DOI: 10.1016/j.toxlet.2016.04.022] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 04/08/2016] [Accepted: 04/22/2016] [Indexed: 11/23/2022]
Abstract
Idiosyncratic drug-induced lever injury (IDILI) is a rare but severe side effect of diclofenac (DF). Several mechanisms have been proposed as cause of DF-induced toxicity including the formation of protein-reactive diclofenac-1',4'-quinone imine (DF-1',4'-QI) and diclofenac-2,5-quinone imine (DF-2,5-QI). Formation of these p-benzoquinone imines result from two-step oxidative metabolism involving aromatic hydroxylation to 4'-hydroxydiclofenac and 5-hydroxydiclofenac followed by dehydrogenation to DF-1',4'-QI and DF-2,5-QI, respectively. Although the contribution of individual cytochrome P450s (CYPs) in aromatic hydroxylation of DF is well studied, the enzymes involved in the dehydrogenation reactions have been poorly characterized. The results of the present study show that both formation of 4'-hydroxydiclofenac and it subsequent bioactivation to DF-1',4'-QI is selectively catalyzed by CYP2C9. However, the two-step bioactivation to DF-2,5-QI appears to be catalyzed with highest activity by two different CYPs: 5-hydroxylation of DF is predominantly catalyzed by CYP3A4, whereas its subsequent bioactivation to DF-2,5-QI is catalyzed with 14-fold higher intrinsic clearance by CYP2C9. The fact that both CYPs involved in two-step bioactivation of DF show large interindividual variability may play a role in different susceptibility of patients to DF-induced IDILI. Furthermore, expression levels of these enzymes and protective enzymes might be important factors determining sensitivity of in vitro models for hepatotoxicity.
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Huber C, Preis M, Harvey PJ, Grosse S, Letzel T, Schröder P. Emerging pollutants and plants--Metabolic activation of diclofenac by peroxidases. CHEMOSPHERE 2016; 146:435-41. [PMID: 26741549 DOI: 10.1016/j.chemosphere.2015.12.059] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 12/15/2015] [Indexed: 05/14/2023]
Abstract
Human pharmaceuticals and their residues are constantly detected in our waterbodies, due to poor elimination rates, even in the most advanced waste water treatment plants. Their impact on the environment and human health still remains unclear. When phytoremediation is applied to aid water treatment, plants may transform and degrade xenobiotic contaminants through phase I and phase II metabolism to more water soluble and less toxic intermediates. In this context, peroxidases play a major role in activating compounds during phase I via oxidation. In the present work, the ability of a plant peroxidase to oxidize the human painkiller diclofenac was confirmed using stopped flow spectroscopy in combination with LC-MS analysis. Analysis of an orange colored product revealed the structure of the highly reactive Diclofenac-2,5-Iminoquinone, which may be the precursor of several biological conjugates and breakdown products in planta.
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Affiliation(s)
- Christian Huber
- Helmholtz Zentrum München Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Ingolstaedter Landstraße 1, D-85764 Neuherberg, Germany
| | - Martina Preis
- School of Science, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
| | - Patricia J Harvey
- School of Science, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
| | - Sylvia Grosse
- Technische Universität München, Lehrstuhl für Siedlungswasserwirtschaft, Am Coulombwall, 85748 Garching, Germany
| | - Thomas Letzel
- Technische Universität München, Lehrstuhl für Siedlungswasserwirtschaft, Am Coulombwall, 85748 Garching, Germany
| | - Peter Schröder
- Helmholtz Zentrum München Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Ingolstaedter Landstraße 1, D-85764 Neuherberg, Germany.
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Turesky RJ, Konorev D, Fan X, Tang Y, Yao L, Ding X, Xie F, Zhu Y, Zhang QY. Effect of Cytochrome P450 Reductase Deficiency on 2-Amino-9H-pyrido[2,3-b]indole Metabolism and DNA Adduct Formation in Liver and Extrahepatic Tissues of Mice. Chem Res Toxicol 2015; 28:2400-10. [PMID: 26583703 PMCID: PMC4703101 DOI: 10.1021/acs.chemrestox.5b00405] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
2-Amino-9H-pyrido[2,3-b]indole (AαC), a carcinogen formed during the combustion of tobacco and cooking of meat, undergoes cytochrome P450 (P450) metabolism to form the DNA adduct N-(deoxyguanosin-8-yl)-2-amino-9H-pyrido[2,3-b]indole (dG-C8-AαC). We evaluated the roles of P450 expressed in the liver and intestine to bioactivate AαC by employing male B6 wild-type (WT) mice, liver-specific P450 reductase (Cpr)-null (LCN) mice, and intestinal epithelium-specific Cpr-null (IECN) mice. Pharmacokinetic parameters were determined for AαC, 2-amino-9H-pyrido[2,3-b]indol-3-yl sulfate (AαC-3-OSO3H), and N(2)-(β-1-glucosidurony1)-2-amino-9H-pyrido[2,3-b]indole (AαC-N(2)-Glu) with animals dosed by gavage with AαC (13.6 mg/kg). The uptake of AαC was rapid with no difference in the plasma half-lives (t1/2) of AαC, AαC-3-OSO3H, and AαC-N(2)-Glu among mouse models. The maximal plasma concentrations (Cmax) and the areas under concentration-time curve (AUC0-24h) of AαC and AαC-N(2)-Glu were 4-24-fold higher in LCN than in WT mice, but they were not different between WT and IECN mice. These findings are consistent with the ablation of hepatic P450 activity in LCN mice. However, the Cmax and AUC0-24h of AαC-3-OSO3H in plasma were not substantially different among the mouse models. Similar pharmacokinetic parameters were obtained with WT and LCN mice treated with a lower AαC dose (1.36 mg kg(-1)). dG-C8-AαC was detected at similar levels in the livers of all three mouse models at the high AαC dose; levels of dG-C8-AαC in colon, bladder, and lung were greater in LCN than in WT mice and were the same in colon of IECN and WT mice. At the low AαC dose, dG-C8-AαC occurred at ∼ 40% lower levels in liver of LCN mouse than in WT mouse liver, but adduct levels remained higher in extrahepatic tissues of LCN mice. Therefore, hepatic P450 plays an important role in detoxication of AαC, but other hepatic or extrahepatic enzymes contribute to the bioactivation of AαC. P450s expressed in the intestine do not appreciably contribute to bioactivation of AαC in mice.
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Affiliation(s)
- Robert J Turesky
- Department of Medicinal Chemistry and Masonic Cancer Center, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Dmitri Konorev
- Department of Medicinal Chemistry and Masonic Cancer Center, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Xiaoyu Fan
- Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York at Albany , Albany, New York 12201, United States
| | - Yijin Tang
- Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York at Albany , Albany, New York 12201, United States
| | - Lihua Yao
- Department of Medicinal Chemistry and Masonic Cancer Center, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Xinxin Ding
- College of Nanoscale Science and Engineering, SUNY Polytechnic Institute , Albany, New York 12203, United States
| | - Fang Xie
- Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York at Albany , Albany, New York 12201, United States
| | - Yi Zhu
- Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York at Albany , Albany, New York 12201, United States
| | - Qing-Yu Zhang
- Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York at Albany , Albany, New York 12201, United States
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15
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Zhu Y, Xie F, Ding L, Fan X, Ding X, Zhang QY. Intestinal epithelium-specific knockout of the cytochrome P450 reductase gene exacerbates dextran sulfate sodium-induced colitis. J Pharmacol Exp Ther 2015; 354:10-7. [PMID: 25926522 DOI: 10.1124/jpet.115.223263] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 04/27/2015] [Indexed: 12/20/2022] Open
Abstract
The potential involvement of intestinal microsomal cytochrome P450 (P450) enzymes in defending against colon inflammation and injury was studied in mice treated with dextran sulfate sodium (DSS) to induce colitis. Wild-type (WT) mice and mice with intestinal epithelium (IE)-specific deletion of the P450 reductase gene (IE-Cpr-null) were compared. IE-Cpr-null mice have little microsomal P450 activity in IE cells. DSS treatment (2.5% in drinking water for 6 days) caused more severe colon inflammation, as evidenced by the presence of higher levels of myeloperoxidase and proinflammatory cytokines [tumor necrosis factor-α, interleukin (IL)-6, and IL-1β], and greater weight loss, colonic tissue damage, and colon shortening, in IE-Cpr-null mice than in WT mice. The IE-Cpr-null mice were deficient in colonic corticosterone (CC) synthesis, as indicated by the inability of ex vivo cultured colonic tissues from DSS-treated IE-Cpr-null mice (in contrast to DSS-treated WT mice) to show increased CC production, compared with vehicle-treated mice, and by the ability of added deoxycorticosterone (DOC), a precursor of CC biosynthesis via mitochondrial CYP11B1, to restore ex vivo CC production by colonic tissues from DSS-treated null mice. Intriguingly, null (but not WT) mice failed to show increased serum CC levels following DSS treatment. Nevertheless, cotreatment of DSS-exposed mice with DOC, which did not restore DSS-induced increase in serum CC, abolished the hypersensitivity of IE-Cpr-null mice to DSS-induced colon injury. Taken together, our results strongly support the notion that microsomal P450 enzymes in the intestine play an important role in protecting colon epithelium from DSS-induced inflammation and injury, possibly through increased local CC synthesis in response to DSS challenge.
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Affiliation(s)
- Yi Zhu
- Wadsworth Center, New York State Department of Health, and School of Public Health, University at Albany, Albany, New York (Y.Z., F.X., L.D., X.F., X.D., Q.-Y.Z.); and College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York (X.D.)
| | - Fang Xie
- Wadsworth Center, New York State Department of Health, and School of Public Health, University at Albany, Albany, New York (Y.Z., F.X., L.D., X.F., X.D., Q.-Y.Z.); and College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York (X.D.)
| | - Liang Ding
- Wadsworth Center, New York State Department of Health, and School of Public Health, University at Albany, Albany, New York (Y.Z., F.X., L.D., X.F., X.D., Q.-Y.Z.); and College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York (X.D.)
| | - Xiaoyu Fan
- Wadsworth Center, New York State Department of Health, and School of Public Health, University at Albany, Albany, New York (Y.Z., F.X., L.D., X.F., X.D., Q.-Y.Z.); and College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York (X.D.)
| | - Xinxin Ding
- Wadsworth Center, New York State Department of Health, and School of Public Health, University at Albany, Albany, New York (Y.Z., F.X., L.D., X.F., X.D., Q.-Y.Z.); and College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York (X.D.)
| | - Qing-Yu Zhang
- Wadsworth Center, New York State Department of Health, and School of Public Health, University at Albany, Albany, New York (Y.Z., F.X., L.D., X.F., X.D., Q.-Y.Z.); and College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York (X.D.)
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16
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Hepatic effects of repeated oral administration of diclofenac to hepatic cytochrome P450 reductase null (HRN™) and wild-type mice. Arch Toxicol 2015; 90:853-62. [DOI: 10.1007/s00204-015-1505-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 03/16/2015] [Indexed: 11/25/2022]
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17
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Dwivedi AK, Gurjar V, Kumar S, Singh N. Molecular basis for nonspecificity of nonsteroidal anti-inflammatory drugs (NSAIDs). Drug Discov Today 2015; 20:863-73. [PMID: 25794602 DOI: 10.1016/j.drudis.2015.03.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 02/18/2015] [Accepted: 03/10/2015] [Indexed: 12/21/2022]
Abstract
Inhibition of the production of inflammatory mediators by the action of nonsteroidal anti-inflammatory drugs (NSAIDs) is highly accredited to their recognition of cyclooxygenase enzymes. Along with inflammation relief, however, NSAIDs also cause adverse effects. Although NSAIDs strongly inhibit enzymes of the prostaglandin synthesis pathways, several other proteins also serve as fairly potent targets for these drugs. Based on their recognition pattern, these receptors are categorised as enzymes modifying NSAIDs, noncatalytic proteins binding to NSAIDs and enzymes with catalytic functions that are inhibited by NSAIDs. The extensive binding of NSAIDs is responsible for their limited in vivo efficacy as well as the large spectrum of their effects. The biochemical nature of drugs binding to multiple protein targets and its implications on physiology are discussed.
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Affiliation(s)
- Avaneesh K Dwivedi
- School of Biotechnology, Gautam Buddha University, Greater Noida, Uttar Pradesh 201308, India
| | - Vaishali Gurjar
- School of Biotechnology, Gautam Buddha University, Greater Noida, Uttar Pradesh 201308, India
| | - Sanjit Kumar
- Center for Bioseparation Technology, VIT University, Vellore, Tamil Nadu 632014, India
| | - Nagendra Singh
- School of Biotechnology, Gautam Buddha University, Greater Noida, Uttar Pradesh 201308, India.
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18
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Evidence of reduced oral bioavailability of paracetamol in rats following multiple ingestion of grapefruit juice. Eur J Drug Metab Pharmacokinet 2014; 41:187-95. [DOI: 10.1007/s13318-014-0251-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Accepted: 12/19/2014] [Indexed: 01/08/2023]
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19
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Kamimura H, Ito S, Nozawa K, Nakamura S, Chijiwa H, Nagatsuka SI, Kuronuma M, Ohnishi Y, Suemizu H, Ninomiya SI. Formation of the Accumulative Human Metabolite and Human-Specific Glutathione Conjugate of Diclofenac in TK-NOG Chimeric Mice with Humanized Livers. Drug Metab Dispos 2014; 43:309-16. [DOI: 10.1124/dmd.114.061689] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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20
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Pongkorpsakol P, Pathomthongtaweechai N, Srimanote P, Soodvilai S, Chatsudthipong V, Muanprasat C. Inhibition of cAMP-activated intestinal chloride secretion by diclofenac: cellular mechanism and potential application in cholera. PLoS Negl Trop Dis 2014; 8:e3119. [PMID: 25188334 PMCID: PMC4154654 DOI: 10.1371/journal.pntd.0003119] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 07/15/2014] [Indexed: 01/01/2023] Open
Abstract
Cyclic AMP-activated intestinal Cl− secretion plays an important role in pathogenesis of cholera. This study aimed to investigate the effect of diclofenac on cAMP-activated Cl− secretion, its underlying mechanisms, and possible application in the treatment of cholera. Diclofenac inhibited cAMP-activated Cl− secretion in human intestinal epithelial (T84) cells with IC50 of ∼20 µM. The effect required no cytochrome P450 enzyme-mediated metabolic activation. Interestingly, exposures of T84 cell monolayers to diclofenac, either in apical or basolateral solutions, produced similar degree of inhibitions. Analyses of the apical Cl− current showed that diclofenac reversibly inhibited CFTR Cl− channel activity (IC50∼10 µM) via mechanisms not involving either changes in intracellular cAMP levels or CFTR channel inactivation by AMP-activated protein kinase and protein phosphatase. Of interest, diclofenac had no effect on Na+-K+ ATPases and Na+-K+-Cl− cotransporters, but inhibited cAMP-activated basolateral K+ channels with IC50 of ∼3 µM. In addition, diclofenac suppressed Ca2+-activated Cl− channels, inwardly rectifying Cl− channels, and Ca2+-activated basolateral K+ channels. Furthermore, diclofenac (up to 200 µM; 24 h of treatment) had no effect on cell viability and barrier function in T84 cells. Importantly, cholera toxin (CT)-induced Cl− secretion across T84 cell monolayers was effectively suppressed by diclofenac. Intraperitoneal administration of diclofenac (30 mg/kg) reduced both CT and Vibrio cholerae-induced intestinal fluid secretion by ∼70% without affecting intestinal fluid absorption in mice. Collectively, our results indicate that diclofenac inhibits both cAMP-activated and Ca2+-activated Cl− secretion by inhibiting both apical Cl− channels and basolateral K+ channels in intestinal epithelial cells. Diclofenac may be useful in the treatment of cholera and other types of secretory diarrheas resulting from intestinal hypersecretion of Cl−. Diarrhea in cholera results from stimulation of cAMP-mediated intestinal Cl− secretion by cholera toxin (CT). This study demonstrates that diclofenac, a widely used non-steroidal anti-inflammatory drug (NSAID), inhibited cAMP-activated Cl− secretion in human intestinal epithelial (T84) cells by inhibiting both apical Cl− channels (i.e. CFTR) and cAMP-activated basolateral K+ channels (i.e. KCNQ1/KCNE3). The mechanism by which CFTR was inhibited did not involve changes in intracellular cAMP levels and activation of negative regulators of CFTR activity including AMP-activated protein kinase (AMPK) and protein phosphatase. In addition, diclofenac suppressed two other types of apical Cl− channels, namely, Ca2+-activated Cl− channels and inwardly rectifying Cl− channels, and Ca2+-activated basolateral K+ channels (i.e. KCa3.1) without affecting Na+-K+ ATPase and Na+-K+-Cl− cotransporter activities. Of particular importance, diclofenac at 30 mg/kg, which is the human equivalent dose for treatment of pain and inflammation (∼2 mg/kg in human), exhibited anti-secretory efficacy in mouse closed-loop models of cholera induced by either CT or V. cholerae. This study provides a rational basis for further development of diclofenac and related compounds as anti-diarrheal therapy for cholera and other types of diarrheas resulting from Cl− transport-driven intestinal fluid secretion.
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Affiliation(s)
- Pawin Pongkorpsakol
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Research Center of Transport Protein for Medical Innovation, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Nutthapoom Pathomthongtaweechai
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Research Center of Transport Protein for Medical Innovation, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Potjanee Srimanote
- Graduate Study, Faculty of Allied Health Sciences, Thammasat University, Pathumtanee, Thailand
| | - Sunhapas Soodvilai
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Research Center of Transport Protein for Medical Innovation, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Varanuj Chatsudthipong
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Research Center of Transport Protein for Medical Innovation, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Chatchai Muanprasat
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Research Center of Transport Protein for Medical Innovation, Faculty of Science, Mahidol University, Bangkok, Thailand
- * E-mail:
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21
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Niu X, de Graaf IAM, van der Bij HA, Groothuis GMM. Precision cut intestinal slices are an appropriate ex vivo model to study NSAID-induced intestinal toxicity in rats. Toxicol In Vitro 2014; 28:1296-305. [PMID: 25014874 DOI: 10.1016/j.tiv.2014.06.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 06/03/2014] [Accepted: 06/23/2014] [Indexed: 12/18/2022]
Abstract
Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used therapeutic agents, however, they are associated with a high prevalence of intestinal side effects. In this investigation, rat precision cut intestinal slices (PCIS) were evaluated as an ex vivo model to study NSAID-induced intestinal toxicity. Firstly, PCIS were incubated with 0-200 μM diclofenac (DCF), one of the most intensively studied NSAIDs, to investigate whether they could correctly reflect the toxic mechanisms. DCF induced intestinal toxicity in PCIS was shown by morphological damage and ATP depletion. DCF induced endoplasmic-reticulum (ER) stress, mitochondrial injury and oxidative stress were reflected by up-regulated HSP-70 (heat shock protein 70) and BiP (binding immunoglobulin protein) gene expression, caspase 9 activation, GSH (glutathione) depletion and HO-1 (heme oxygenase 1) gene up-regulation respectively. Furthermore, DCF intestinal metabolites, which gave rise to protein adduct but not toxicity, were detected in PCIS. Secondly, PCIS were incubated with various concentrations of five NSAIDs. Typical NSAID-induced morphological changes were observed in PCIS. The ex vivo toxicity ranking (diflunisal> diclofenac = indomethacin > naproxen ≫ aspirin) showed good correlation with published in vitro and in vivo data, with diflunisal being the only exception. In conclusion, PCIS correctly reflect the various mechanisms of DCF-induced intestinal toxicity, and can serve as an ex vivo model for the prediction of NSAID-induced intestinal toxicity.
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Affiliation(s)
- Xiaoyu Niu
- Division of Pharmacokinetics, Toxicology and Targeting, Department of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Inge A M de Graaf
- Division of Pharmacokinetics, Toxicology and Targeting, Department of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.
| | - Hendrik A van der Bij
- Division of Pharmacokinetics, Toxicology and Targeting, Department of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Geny M M Groothuis
- Division of Pharmacokinetics, Toxicology and Targeting, Department of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
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22
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Ahlawat S, Xie F, Zhu Y, D'Hondt R, Ding X, Zhang QY, Mantis NJ. Mice deficient in intestinal epithelium cytochrome P450 reductase are prone to acute toxin-induced mucosal damage. Sci Rep 2014; 4:5551. [PMID: 24989705 PMCID: PMC4080431 DOI: 10.1038/srep05551] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 06/11/2014] [Indexed: 12/19/2022] Open
Abstract
Cytochrome P450 (P450) enzymes are a superfamily of heme-containing enzymes involved in the metabolism of various endogenous compounds, including retinoids, glucocorticoids, and eicosanoids, that are postulated to participate in the maintenance and/or development of inflammatory and immune reactions in the intestinal mucosa. To investigate the role of P450 enzymes in intestinal inflammation and immunity, we took advantage of IE-Cpr-null mice, which are deficient in intestinal epithelium of NADPH-cytochrome P450 reductase (CPR), the obligate redox partner of all microsomal P450 enzymes. We report that IE-Cpr-null mice, following an acute toxin challenge, had higher levels of pro-inflammatory chemokines and increased tissue damage compared to wild-type mice. IE-Cpr-null mice had normal Peyer's patch numbers and elicited normal secretory IgA (SIgA) responses. However, SIgA baseline levels in IE-Cpr-null mice were consistently elevated over WT littermates. While neither retinoic acid nor glucocorticoid levels in serum and intestinal homogenates were altered in IE-Cpr-null mice, basal levels of arachidonic acid metabolites (11,12-DiHETE and 14,15-DiHETE) with known anti-inflammatory property were significantly lower compared to WT controls. Overall, these findings reveal immunological and metabolic changes resulting from a genetic deficiency in CPR expression in the intestine, and support a role for microsomal P450 enzymes in mucosal homeostasis and immunity.
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Affiliation(s)
- Sarita Ahlawat
- 1] Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY [2]
| | - Fang Xie
- 1] Division of Environmental Health Sciences, Wadsworth Center, New York State Department of Health, Albany, NY [2]
| | - Yi Zhu
- 1] Division of Environmental Health Sciences, Wadsworth Center, New York State Department of Health, Albany, NY [2] Departments of Environmental Health Sciences, University at Albany, Albany, NY 12208
| | - Rebecca D'Hondt
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY
| | - Xinxin Ding
- 1] Division of Environmental Health Sciences, Wadsworth Center, New York State Department of Health, Albany, NY [2] Departments of Environmental Health Sciences, University at Albany, Albany, NY 12208 [3] Biomedical Sciences, University at Albany, Albany, NY 12208
| | - Qing-Yu Zhang
- 1] Division of Environmental Health Sciences, Wadsworth Center, New York State Department of Health, Albany, NY [2] Departments of Environmental Health Sciences, University at Albany, Albany, NY 12208
| | - Nicholas J Mantis
- 1] Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY [2] Biomedical Sciences, University at Albany, Albany, NY 12208
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23
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Diclofenac toxicity in human intestine ex vivo is not related to the formation of intestinal metabolites. Arch Toxicol 2014; 89:107-19. [PMID: 24770551 DOI: 10.1007/s00204-014-1242-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 04/10/2014] [Indexed: 12/22/2022]
Abstract
The use of diclofenac (DCF), a nonsteroidal anti-inflammatory drug, is associated with a high prevalence of gastrointestinal side effects. In vivo studies in rodents suggested that reactive metabolites of DCF produced by the liver or the intestine might be responsible for this toxicity. In the present study, precision-cut intestinal slices (PCIS) prepared from the jejunum of 18 human donors were used as an ex vivo model to investigate whether DCF intestinal metabolites are responsible for its intestinal toxicity in man. PCIS were incubated with a concentration range of DCF (0-600 µM) up to 24 h. DCF (≥400 µM) caused direct toxicity to the intestine as demonstrated by ATP depletion, morphological damage, caspase 3 activation, and lactate dehydrogenase leakage. Three main metabolites produced by PCIS (4'-hydroxy DCF, 5-hydroxy DCF, and DCF acyl glucuronide) were detected by HPLC. Protein adducts were detected by immunohistochemical staining and showed correlation with the intestinal metabolites. DCF induced similar toxicity to each of the samples regardless of the variation in metabolism among them. Less metabolites were produced by slices incubated with 400 µM DCF than with 100 µM DCF. The addition of the metabolic inhibitors such as ketoconazole, cimetidine, or borneol decreased the metabolite formation but increased the toxicity. The results suggest that DCF can induce intestinal toxicity in human PCIS directly at therapeutically relevant concentrations, independent of the reactive metabolites 4'-OH DCF, 5-OH DCF, or diclofenac acylglucuronide produced by the liver or formed in the intestine.
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24
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Megaraj V, Ding X, Fang C, Kovalchuk N, Zhu Y, Zhang QY. Role of hepatic and intestinal p450 enzymes in the metabolic activation of the colon carcinogen azoxymethane in mice. Chem Res Toxicol 2014; 27:656-62. [PMID: 24552495 PMCID: PMC4002058 DOI: 10.1021/tx4004769] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
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P450-mediated
bioactivation of azoxymethane (AOM), a colon carcinogen,
leads to the formation of DNA adducts, of which O6-methylguanine (O6-mG) is the most mutagenic
and contributes to colon tumorigenesis. To determine whether P450
enzymes of the liver and intestine both contribute to AOM bioactivation in vivo, we compared tissue levels of AOM-induced DNA adducts,
microsomal AOM metabolic activities, and incidences of colonic aberrant
crypt foci (ACF) among wild-type (WT), liver-specific P450 reductase
(Cpr)-null (LCN), and intestinal epithelium-specific Cpr-null (IECN)
mice. At 6 h following AOM treatment (at 14 mg/kg, s.c.), O6-mG and N7-mG levels were highest in the liver, followed
by the colon, and then small intestine in WT mice. As expected, hepatic
adduct levels were significantly lower (by >60%) in LCN mice but
unchanged
in IECN mice, whereas small-intestinal adduct levels were unchanged
or increased in LCN mice but lower (by >50%) in IECN mice compared
to that in WT mice. However, colonic adduct levels were unchanged
in IECN mice compared to that in WT mice and increased in LCN mice
(by 1.5–2.9-fold). The tissue-specific impact of the CPR loss
in IECN and LCN mice on microsomal AOM metabolic activity was confirmed
by rates of formation of formaldehyde and N7-mG in vitro. Furthermore, the incidence of ACF, a lesion preceding
colon cancer, was similar in the three mouse strains. Thus, AOM-induced
colonic DNA damage and ACF formation is not solely dependent on either
hepatic or intestinal microsomal P450 enzymes. P450 enzymes in both
the liver and intestine likely contribute to AOM-induced colon carcinogenesis.
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Affiliation(s)
- Vandana Megaraj
- Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York at Albany , Albany, New York 12201, United States
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25
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Vredenburg G, Elias NS, Venkataraman H, Hendriks DFG, Vermeulen NPE, Commandeur JNM, Vos JC. Human NAD(P)H:quinone Oxidoreductase 1 (NQO1)-Mediated Inactivation of Reactive Quinoneimine Metabolites of Diclofenac and Mefenamic Acid. Chem Res Toxicol 2014; 27:576-86. [DOI: 10.1021/tx400431k] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Galvin Vredenburg
- Division
of Molecular Toxicology,
Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty
of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Naura S. Elias
- Division
of Molecular Toxicology,
Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty
of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Harini Venkataraman
- Division
of Molecular Toxicology,
Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty
of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Delilah F. G. Hendriks
- Division
of Molecular Toxicology,
Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty
of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Nico P. E. Vermeulen
- Division
of Molecular Toxicology,
Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty
of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Jan N. M. Commandeur
- Division
of Molecular Toxicology,
Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty
of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - J. Chris Vos
- Division
of Molecular Toxicology,
Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty
of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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Dragovic S, Venkataraman H, Begheijn S, Vermeulen NP, Commandeur JN. Effect of human glutathione S-transferase hGSTP1-1 polymorphism on the detoxification of reactive metabolites of clozapine, diclofenac and acetaminophen. Toxicol Lett 2014; 224:272-81. [DOI: 10.1016/j.toxlet.2013.10.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 10/19/2013] [Accepted: 10/23/2013] [Indexed: 01/01/2023]
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Dragovic S, Boerma JS, Vermeulen NPE, Commandeur JNM. Effect of Human Glutathione S-Transferases on Glutathione-Dependent Inactivation of Cytochrome P450-Dependent Reactive Intermediates of Diclofenac. Chem Res Toxicol 2013; 26:1632-41. [DOI: 10.1021/tx400204d] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Sanja Dragovic
- Division of Molecular Toxicology,
Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty
of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Jan Simon Boerma
- Division of Molecular Toxicology,
Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty
of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Nico P. E. Vermeulen
- Division of Molecular Toxicology,
Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty
of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Jan N. M. Commandeur
- Division of Molecular Toxicology,
Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Faculty
of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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Cornejo-García JA, Liou LB, Blanca-López N, Doña I, Chen CH, Chou YC, Chuang HP, Wu JY, Chen YT, Plaza-Serón MDC, Mayorga C, Guéant-Rodríguez RM, Lin SC, Torres MJ, Campo P, Rondón C, Laguna JJ, Fernández J, Guéant JL, Canto G, Blanca M, Lee MTM. Genome-wide association study in NSAID-induced acute urticaria/angioedema in Spanish and Han Chinese populations. Pharmacogenomics 2013; 14:1857-69. [PMID: 24236485 DOI: 10.2217/pgs.13.166] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
AIM Acute urticaria/angioedema (AUA) induced by cross-intolerance to NSAIDs is the most frequent clinical entity in hypersensitivity reactions to drugs. In this work, we conducted a genome-wide association study in Spanish and Han Chinese patients suffering from NSAID-induced AUA. MATERIALS & METHODS A whole-genome scan was performed on a total of 232 cases (112 Spanish and 120 Han Chinese) with NSAID-induced AUA and 225 unrelated controls (124 Spanish and 101 Han Chinese). RESULTS Although no polymorphism reached genome-wide significance, we obtained suggestive associations for three clusters in the Spanish group (RIMS1, BICC1 and RAD51L 1) and one region in the Han Chinese population (ABI3BP). Five regions showed suggestive associations after meta-analysis: HLF, RAD51L1, COL24A1, GalNAc-T13 and FBXL7. A majority of these genes are related to Ca(2+), cAMP and/or P53 signaling pathways. CONCLUSION The associations described were different from those related to the metabolism of arachidonic acid and could provide new mechanisms underlying NSAID-induced AUA.
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29
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Zhu Y, Ding X, Fang C, Zhang QY. Regulation of intestinal cytochrome P450 expression by hepatic cytochrome P450: possible involvement of fibroblast growth factor 15 and impact on systemic drug exposure. Mol Pharmacol 2013; 85:139-47. [PMID: 24184963 DOI: 10.1124/mol.113.088914] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Tissue-specific deletion of the gene for NADPH-cytochrome P450 (P450) reductase (CPR), the essential electron donor to all microsomal P450 enzymes, in either liver or intestine, leads to upregulation of many P450 genes in the tissue with the Cpr deletion. Here, by studying the liver-specific Cpr-null (LCN) mouse, we examined whether an interorgan regulatory pathway exists, such that a loss of hepatic CPR would cause compensatory changes in intestinal P450 expression and capacity for first-pass metabolism of oral drugs. We show for the first time that intestinal expression of CYP2B, 2C, and 3A proteins was increased in LCN mice by 2- to 3-fold compared with wild-type (WT) mice, accompanied by significant increases in small intestinal microsomal lovastatin-hydroxylase activity and systemic clearance of oral lovastatin (at 5 mg/kg). Additional studies showed that the hepatic Cpr deletion, which caused large decreases in bile acid (BA) levels in the liver, intestine, plasma, and intestinal content, led to drastic decreases in the mRNA levels of intestinal fibroblast growth factor 15 (FGF15), a target gene of the BA receptor farnesoid X receptor. Furthermore, treatment of mice with FGF19 (the human counterpart of mouse FGF15) abolished the difference between WT and LCN mice in small intestinal (SI) CYP3A levels at 6 hours after the treatment. Our findings reveal a previously unrecognized direct role of intestinal FGF15/19 in the regulation of SI P450 expression and may have profound implications for the prediction of drug exposure in patients with compromised hepatic P450 function.
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Affiliation(s)
- Yi Zhu
- Laboratory of Molecular Toxicology, Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York at Albany, Albany, New York
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Saitta KS, Zhang C, Lee KK, Fujimoto K, Redinbo MR, Boelsterli UA. Bacterial β-glucuronidase inhibition protects mice against enteropathy induced by indomethacin, ketoprofen or diclofenac: mode of action and pharmacokinetics. Xenobiotica 2013; 44:28-35. [PMID: 23829165 DOI: 10.3109/00498254.2013.811314] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
1. We have previously demonstrated that a small molecule inhibitor of bacterial β-glucuronidase (Inh-1; [1-((6,8-dimethyl-2-oxo-1,2-dihydroquinolin-3-yl)-3-(4-ethoxyphenyl)-1-(2-hydroxyethyl)thiourea]) protected mice against diclofenac (DCF)-induced enteropathy. Here we report that Inh-1 was equally protective against small intestinal injury induced by other carboxylic acid-containing non-steroidal anti-inflammatory drugs (NSAIDs), indomethacin (10 mg/kg, ip) and ketoprofen (100 mg/kg, ip). 2. Inh-1 provided complete protection if given prior to DCF (60 mg/kg, ip), and partial protection if administered 3-h post-DCF, suggesting that the temporal window of mucosal protection can be extended for drugs undergoing extensive enterohepatic circulation. 3. Pharmacokinetic analysis of Inh-1 revealed an absolute bioavailability (F) of 21% and a short t1/2 of <1 h. This low F was shown to be due to hepatic first-pass metabolism, as confirmed with the pan-CYP inhibitor, 1-aminobenzotriazole. 4. Using the fluorescent probe 5 (and 6)-carboxy-2',7'-dichlorofluorescein, we demonstrated that Inh-1 did not interfere with hepatobiliary export of glucuronides in gall bladder-cannulated mice. 5. These data are compatible with the hypothesis that pharmacological inhibition of bacterial β-glucuronidase-mediated cleavage of NSAID glucuronides in the small intestinal lumen can protect against NSAID-induced enteropathy caused by locally high concentrations of NSAID aglycones.
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Affiliation(s)
- Kyle S Saitta
- Department of Pharmaceutical Sciences, University of Connecticut School of Pharmacy , Storrs, Connecticut , USA and
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31
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Wallace BD, Redinbo MR. The human microbiome is a source of therapeutic drug targets. Curr Opin Chem Biol 2013; 17:379-84. [PMID: 23680493 DOI: 10.1016/j.cbpa.2013.04.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 04/02/2013] [Accepted: 04/09/2013] [Indexed: 12/13/2022]
Abstract
It was appreciated early in drug discovery that the microbiota play an important role in the efficacy of therapeutic compounds. Indeed, the first antibiotic sulfa drugs were shown in the 1940s to be transformed by the bacteria that encode what we now call the intestinal microbiome. Here we briefly review the roles symbiotic bacteria play in the chemistry of human health, and we focus on the emerging appreciation that specific enzyme targets expressed by microbial symbiotes can be selectively disrupted to achieve clinical outcomes. We conclude that components of the microbiome should be considered 'druggable targets,' and we suggest that our rapidly evolving understanding of the chemical biology of mammalian-microbial symbiosis will translate into improved human health.
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Affiliation(s)
- Bret D Wallace
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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32
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Boelsterli UA. How close are we to developing enteric-protective drugs against non-steroidal anti-inflammatory drug-induced small intestinal injury? New mechanistic insight from preclinical models. J Gastroenterol Hepatol 2013; 28:589-90. [PMID: 23527755 DOI: 10.1111/jgh.12102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/17/2012] [Indexed: 12/09/2022]
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Boelsterli UA, Redinbo MR, Saitta KS. Multiple NSAID-induced hits injure the small intestine: underlying mechanisms and novel strategies. Toxicol Sci 2012; 131:654-67. [PMID: 23091168 DOI: 10.1093/toxsci/kfs310] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Nonsteroidal anti-inflammatory drugs (NSAIDs) can cause serious gastrointestinal (GI) injury including jejunal/ileal mucosal ulceration, bleeding, and even perforation in susceptible patients. The underlying mechanisms are largely unknown, but they are distinct from those related to gastric injury. Based on recent insights from experimental models, including genetics and pharmacology in rodents typically exposed to diclofenac, indomethacin, or naproxen, we propose a multiple-hit pathogenesis of NSAID enteropathy. The multiple hits start with an initial pharmacokinetic determinant caused by vectorial hepatobiliary excretion and delivery of glucuronidated NSAID or oxidative metabolite conjugates to the distal small intestinal lumen, where bacterial β-glucuronidase produces critical aglycones. The released aglycones are then taken up by enterocytes and further metabolized by intestinal cytochrome P450s to potentially reactive intermediates. The "first hit" is caused by the NSAID and/or oxidative metabolites that induce severe endoplasmic reticulum stress or mitochondrial stress and lead to cell death. The "second hit" is created by the significant subsequent inflammatory response that would follow such a first-hit injury. Based on these putative mechanisms, strategies have been developed to protect the enterocytes from being exposed to the parent NSAID and/or oxidative metabolites. Among these, a novel strategy already demonstrated in a murine model is the selective disruption of bacteria-specific β-glucuronidases with a novel small molecule inhibitor that does not harm the bacteria and that alleviates NSAID-induced enteropathy. Such mechanism-based strategies require further investigation but provide potential avenues for the alleviation of the GI toxicity caused by multiple NSAID hits.
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Affiliation(s)
- Urs A Boelsterli
- Department of Pharmaceutical Sciences, University of Connecticut School of Pharmacy, Storrs, Connecticut 06269, USA.
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Riddick DS, Ding X, Wolf CR, Porter TD, Pandey AV, Zhang QY, Gu J, Finn RD, Ronseaux S, McLaughlin LA, Henderson CJ, Zou L, Flück CE. NADPH-cytochrome P450 oxidoreductase: roles in physiology, pharmacology, and toxicology. Drug Metab Dispos 2012; 41:12-23. [PMID: 23086197 DOI: 10.1124/dmd.112.048991] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
This is a report on a symposium sponsored by the American Society for Pharmacology and Experimental Therapeutics and held at the Experimental Biology 2012 meeting in San Diego, California, on April 25, 2012. The symposium speakers summarized and critically evaluated our current understanding of the physiologic, pharmacological, and toxicological roles of NADPH-cytochrome P450 oxidoreductase (POR), a flavoprotein involved in electron transfer to microsomal cytochromes P450 (P450), cytochrome b(5), squalene mono-oxygenase, and heme oxygenase. Considerable insight has been derived from the development and characterization of mouse models with conditional Por deletion in particular tissues or partial suppression of POR expression in all tissues. Additional mouse models with global or conditional hepatic deletion of cytochrome b(5) are helping to clarify the P450 isoform- and substrate-specific influences of cytochrome b(5) on P450 electron transfer and catalytic function. This symposium also considered studies using siRNA to suppress POR expression in a hepatoma cell-culture model to explore the basis of the hepatic lipidosis phenotype observed in mice with conditional deletion of Por in liver. The symposium concluded with a strong translational perspective, relating the basic science of human POR structure and function to the impacts of POR genetic variation on human drug and steroid metabolism.
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Affiliation(s)
- David S Riddick
- Department of Pharmacology and Toxicology, Medical Sciences Building, University of Toronto, Toronto, Ontario, Canada M5S 1A8.
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