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Chenchen H, Keqi H, Yanhong Z, Yiye J, Yankuan T, Xiaojun L, Bixian M. In vitro hepatic metabolism of polychlorinated biphenyls with different chlorine-substituted structures in rats and humans: Kinetics, metabolism, and potential nuclear receptor affinities. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 864:161043. [PMID: 36549545 DOI: 10.1016/j.scitotenv.2022.161043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 12/14/2022] [Accepted: 12/15/2022] [Indexed: 06/17/2023]
Abstract
In this study, the biotransformation behavior and potential nuclear receptor affinities of polychlorinated biphenyls (PCBs) with different chlorine-substituted structures (PCB 77/110/136/174) were explored using human and rat liver microsomes (HLM and RLM). The rate constants (kobs) of PCBs showed the variations in the order patterns for the HLM (PCB 136 > PCB 110 > PCB 174 > PCB 77) and RLM (PCB 110 > PCB 136 > PCB 174 > PCB 77). However, studied PCBs showed similar metabolite profiles and enantioselective of PCBs between HLM and RLM. The Mono-OH-PCBs were the major metabolites of PCB 77/174, whereas mono-OH- and di-OH-PCBs were the major metabolites of PCB 110/136 for the HLM and RLM, indicating that OH-PCBs could be further oxidized. Enantiomeric enrichment of (-)-PCB 136 and (+)-PCB 174 was observed in microsomal metabolism. Moreover, the inflection point of the enantiomer fraction for PCB 136 metabolized by the HLM suggests a competitive metabolism between individual atropisomers. Furthermore, molecular docking results demonstrated the relatively high affinity between PCBs (or OH-PCBs) and certain nuclear receptors, indicating that abnormal metabolic enzyme expression and endocrine disruption occur in PCB-exposed humans.
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Affiliation(s)
- Huang Chenchen
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; China University of Mining & Technology, School of Environmental Science & Spatial Informatics, Xuzhou 221116, Jiangsu, China
| | - Hu Keqi
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-MaCao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Zeng Yanhong
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-MaCao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
| | - Jiang Yiye
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tian Yankuan
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-MaCao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Luo Xiaojun
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-MaCao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Mai Bixian
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
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Šimečková P, Pěnčíková K, Kováč O, Slavík J, Pařenicová M, Vondráček J, Machala M. In vitro profiling of toxic effects of environmental polycyclic aromatic hydrocarbons on nuclear receptor signaling, disruption of endogenous metabolism and induction of cellular stress. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 815:151967. [PMID: 34843781 DOI: 10.1016/j.scitotenv.2021.151967] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 11/03/2021] [Accepted: 11/22/2021] [Indexed: 06/13/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) may interact with multiple intracellular receptors and related signaling pathways. We comprehensively evaluated the toxicity profiles of six environmentally relevant PAHs differing in structure, genotoxicity and their ability to activate the aryl hydrocarbon receptor (AhR). We focused particularly on their impact on intracellular hormone-, xenobiotic- and lipid-sensing receptors, as well as on cellular stress markers, combining a battery of human reporter gene assays and qRT-PCR evaluation of endogenous gene expression in human hepatocyte-like HepaRG cells, with LC/MS-MS analysis of cellular sphingolipids. The effects of PAHs included: activation of estrogen receptor α (in case of fluoranthene (Fla), pyrene (Pyr), benz[a]anthracene (BaA), benzo[a]pyrene (BaP)), suppression of androgen receptor activity (Fla, BaA, BaP and benzo[k]fluoranthene (BkF)), enhancement of dexamethasone-induced glucocorticoid receptor activity (chrysene (Chry), BaA, and BaP), and potentiation of triiodothyronine-induced thyroid receptor α activity (all tested PAHs). PAHs also induced transcription of endogenous gene targets of constitutive androstane receptor (Fla, Pyr), or repression of target genes of pregnane X receptor and peroxisome proliferator-activated receptor α (in case of the AhR-activating PAHs - Chry, BaA, BaP, and BkF) in HepaRG cells. In the same cell model, the AhR agonists reduced the expression of glucose metabolism genes (PCK1, G6PC and PDK4), and they up-regulated levels of glucosylceramides, together with a concomitant induction of expression of UGCG, glucosylceramide synthesis enzyme. Finally, both BaP and BkF were found to induce expression of early stress and genotoxicity markers: ATF3, EGR1, GDF15, CDKN1A/p21, and GADD45A mRNAs, while BaP alone increased levels of IL-6 mRNA. Overall, whereas low-molecular-weight PAHs exerted significant effects on nuclear receptors (with CYP2B6 induction observed already at nanomolar concentrations), the AhR activation by 4-ring and 5-ring PAHs appeared to be a key mechanism underlying their impact on nuclear receptor signaling, endogenous metabolism and induction of early stress and genotoxicity markers.
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Affiliation(s)
- Pavlína Šimečková
- Department of Pharmacology and Toxicology, Veterinary Research Institute, 62100 Brno, Czech Republic
| | - Kateřina Pěnčíková
- Department of Pharmacology and Toxicology, Veterinary Research Institute, 62100 Brno, Czech Republic
| | - Ondrej Kováč
- Department of Pharmacology and Toxicology, Veterinary Research Institute, 62100 Brno, Czech Republic
| | - Josef Slavík
- Department of Pharmacology and Toxicology, Veterinary Research Institute, 62100 Brno, Czech Republic
| | - Martina Pařenicová
- Department of Pharmacology and Toxicology, Veterinary Research Institute, 62100 Brno, Czech Republic
| | - Jan Vondráček
- Department of Cytokinetics, Institute of Biophysics of the Czech Academy of Sciences, 61265 Brno, Czech Republic
| | - Miroslav Machala
- Department of Pharmacology and Toxicology, Veterinary Research Institute, 62100 Brno, Czech Republic.
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Guo F, Yin S, Wang H, Zhang J, Liu Y, Aamir M, Liu W. Polychlorinated biphenyls (PCBs) in the colostrum samples from the Yangtze River Region: Exposure profile and risk assessment. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 285:117253. [PMID: 33957509 DOI: 10.1016/j.envpol.2021.117253] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 04/21/2021] [Accepted: 04/23/2021] [Indexed: 06/12/2023]
Abstract
Polychlorinated biphenyls (PCBs) may transfer into the neonates through the placental transfer and via breastfeeding after the delivery, thus might be harmful to the infant. Sixty colostrum samples in the Yangtze River Region were collected to investigate the concentration, distribution pattern, and enantiomer characteristic of the PCB exposure. Among all samples, over 90% of pollutants were tetra-to hepta-chlorinated PCBs. The sum concentration of the PCB was 512 (IQR: 322-856) ng g-1 lipid weight. Enantiomer fraction (EF) of PCB 95 and PCB 149 was found lower than the racemic value, while EFs of PCB 45 and PCB 136 were found higher and near-racemic state, respectively. The concentration pattern and enantiomeric properties of the PCBs indicated that the mothers from Mianyang had a recent exposure to PCBs. Among all samples, similar exposure and metabolic pathways of the PCB congeners were observed. PCB exposure showed no significant correlation with the birth outcome of the infants, but 43.3% of the infants have potential health risks via breastfeeding.
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Affiliation(s)
- Fangjie Guo
- Quality and Safety Engineering Institute of Food and Drug, School of Management Engineering and Electronic Commerce, Zhejiang Gongshang University, Hangzhou, 310018, Zhejiang, China
| | - Shanshan Yin
- Interdisciplinary Research Academy (IRA), Zhejiang Shuren University, Hangzhou, 310015, China.
| | - Haiyan Wang
- Quality and Safety Engineering Institute of Food and Drug, School of Management Engineering and Electronic Commerce, Zhejiang Gongshang University, Hangzhou, 310018, Zhejiang, China
| | - Jianyun Zhang
- Department of Nutrition and Toxicology, School of Public Health, Faculty of Medicine, Hangzhou Normal University, 311121, China
| | - Yingxue Liu
- Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, Institution of Environmental Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Muhammad Aamir
- Water-Energy Resilience Research Laboratory, Environmental Science and Engineering, School of Engineering, Westlake University, Hangzhou, 310024, China
| | - Weiping Liu
- Interdisciplinary Research Academy (IRA), Zhejiang Shuren University, Hangzhou, 310015, China
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Zhu L, Huo X, Zhou J, Zhang Q, Wang W. Metabolic activation mechanism of 2,2',3,3',6,6'-hexachlorobiphenyl (PCB136) by cytochrome P450 2B6: A QM/MM approach. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 776:145579. [PMID: 33652317 DOI: 10.1016/j.scitotenv.2021.145579] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 01/28/2021] [Accepted: 01/28/2021] [Indexed: 06/12/2023]
Abstract
Cytochrome P450 enzymes (CYPs) play an essential role in the bio-transformation of polychlorinated biphenyls (PCBs). The present work implemented quantum mechanic/molecular mechanic methods (QM/MM) and density functional theory (DFT) to study the metabolic activation of 2,2',3,3',6,6'-hexachlorobiphenyl (PCB136) catalyzed by CYP2B6. Electrophilic additions at the Cα and Cβ positions generate different active intermediates. The electrophilic addition energy barrier of Cβ is 10.9 kcal/mol higher than that of Cα, and Cα is the preferred site for the electrophilic addition reaction. Based on the previous experimental studies, this work investigated the mechanism of converting active intermediates into OH-PCB136, which has high toxicity in a non-enzymatic environment. Structural analysis via the electrostatic and noncovalent interactions indicates that Phe108, Ile114, Phe115, Phe206, Phe297, Ala298, Leu363, Val367, TIP32475 and TIP32667 play crucial roles in substrate recognition and metabolism. The analysis suggests that the halogen-π interactions are important factors for the metabolism of CYP2B6 to halogenated environmental pollutants. This work improved the understanding of the metabolism and activation process of chiral PCBs, and can be used as a guide to improve the microbial degradation efficiency of PCB136.
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Affiliation(s)
- Ledong Zhu
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Xinxi Huo
- Environment Research Institute, Shandong University, Qingdao 266237, PR China; Office of Supervisory and Audit, Shandong University, Qingdao 266237, PR China
| | - Jie Zhou
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University, Qingdao 266237, PR China.
| | - Wenxing Wang
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
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Šimečková P, Hubatka F, Kotouček J, Turánek Knötigová P, Mašek J, Slavík J, Kováč O, Neča J, Kulich P, Hrebík D, Stráská J, Pěnčíková K, Procházková J, Diviš P, Macaulay S, Mikulík R, Raška M, Machala M, Turánek J. Gadolinium labelled nanoliposomes as the platform for MRI theranostics: in vitro safety study in liver cells and macrophages. Sci Rep 2020; 10:4780. [PMID: 32179785 PMCID: PMC7075985 DOI: 10.1038/s41598-020-60284-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 12/18/2019] [Indexed: 12/14/2022] Open
Abstract
Gadolinium (Gd)-based contrast agents are extensively used for magnetic resonance imaging (MRI). Liposomes are potential nanocarrier-based biocompatible platforms for development of new generations of MRI diagnostics. Liposomes with Gd-complexes (Gd-lip) co-encapsulated with thrombolytic agents can serve both for imaging and treatment of various pathological states including stroke. In this study, we evaluated nanosafety of Gd-lip containing PE-DTPA chelating Gd+3 prepared by lipid film hydration method. We detected no cytotoxicity of Gd-lip in human liver cells including cancer HepG2, progenitor (non-differentiated) HepaRG, and differentiated HepaRG cells. Furthermore, no potential side effects of Gd-lip were found using a complex system including general biomarkers of toxicity, such as induction of early response genes, oxidative, heat shock and endoplasmic reticulum stress, DNA damage responses, induction of xenobiotic metabolizing enzymes, and changes in sphingolipid metabolism in differentiated HepaRG. Moreover, Gd-lip did not show pro-inflammatory effects, as assessed in an assay based on activation of inflammasome NLRP3 in a model of human macrophages, and release of eicosanoids from HepaRG cells. In conclusion, this in vitro study indicates potential in vivo safety of Gd-lip with respect to hepatotoxicity and immunopathology caused by inflammation.
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Affiliation(s)
| | | | - Jan Kotouček
- Veterinary Research Institute, Brno, Czech Republic
| | | | - Josef Mašek
- Veterinary Research Institute, Brno, Czech Republic
| | - Josef Slavík
- Veterinary Research Institute, Brno, Czech Republic
| | - Ondrej Kováč
- Veterinary Research Institute, Brno, Czech Republic
| | - Jiří Neča
- Veterinary Research Institute, Brno, Czech Republic
| | - Pavel Kulich
- Veterinary Research Institute, Brno, Czech Republic
| | - Dominik Hrebík
- Central European Institute of Technology CEITEC, Structural Virology, Masaryk University, Brno, Czech Republic
| | - Jana Stráská
- Regional Centre of Advanced Technologies and Materials, Palacký University, Olomouc, Czech Republic
| | | | | | - Pavel Diviš
- Faculty of Chemistry, Technical University, Brno, Czech Republic
| | | | - Robert Mikulík
- International Clinical Research Centre, St. Anne's University Hospital Brno, Brno, Czech Republic
- Neurology Department, St. Anne's University Hospital and Masaryk University, Brno, Czech Republic
| | - Milan Raška
- Veterinary Research Institute, Brno, Czech Republic
- Department of Immunology, Faculty of Medicine and Dentistry, Palacký University, Olomouc, Czech Republic
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Buha Djordjevic A, Antonijevic E, Curcic M, Milovanovic V, Antonijevic B. Endocrine-disrupting mechanisms of polychlorinated biphenyls. CURRENT OPINION IN TOXICOLOGY 2020. [DOI: 10.1016/j.cotox.2019.10.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Uwimana E, Cagle B, Yeung C, Li X, Patterson EV, Doorn JA, Lehmler HJ. Atropselective Oxidation of 2,2',3,3',4,6'-Hexachlorobiphenyl (PCB 132) to Hydroxylated Metabolites by Human Liver Microsomes and Its Implications for PCB 132 Neurotoxicity. Toxicol Sci 2019; 171:406-420. [PMID: 31268529 PMCID: PMC6760323 DOI: 10.1093/toxsci/kfz150] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 06/18/2019] [Accepted: 06/18/2019] [Indexed: 02/05/2023] Open
Abstract
Polychlorinated biphenyls (PCBs) have been associated with neurodevelopmental disorders. Several neurotoxic congeners display axial chirality and atropselectively affect cellular targets implicated in PCB neurotoxicity. Only limited information is available regarding the atropselective metabolism of these congeners in humans and their atropselective effects on neurotoxic outcomes. Here we investigate the hypothesis that the oxidation of 2,2',3,3',4,6'-hexachlorobiphenyl (PCB 132) by human liver microsomes (HLMs) and their effects on dopaminergic cells in culture are atropselective. Racemic PCB 132 was incubated with pooled or single donor HLMs, and levels and enantiomeric fractions of PCB 132 and its metabolites were determined gas chromatographically. The major metabolite was either 2,2',3,4,4',6'-hexachlorobiphenyl-3'-ol (3'-140), a 1,2-shift product, or 2,2',3,3',4,6'-hexachlorobiphenyl-5'-ol (5'-132). The PCB 132 metabolite profiles displayed inter-individual differences and depended on the PCB 132 atropisomer. Computational studies suggested that 3'-140 is formed via a 3,4-arene oxide intermediate. The second eluting atropisomer of PCB 132, first eluting atropisomer of 3'-140, and second eluting atropisomer of 5'-132 were enriched in all HLM incubations. Enantiomeric fractions of the PCB 132 metabolites differed only slightly between the single donor HLM preparations investigated. Reactive oxygen species and levels of dopamine and its metabolites were not significantly altered after a 24 h exposure of dopaminergic cells to pure PCB 132 atropisomers. These findings suggest that there are inter-individual differences in the atropselective biotransformation of PCB 132 to its metabolites in humans; however, the resulting atropisomeric enrichment of PCB 132 is unlikely to affect neurotoxic outcomes associated with the endpoints investigated in the study.
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Affiliation(s)
- Eric Uwimana
- Interdisciplinary Graduate Program in Human Toxicology and Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa
| | - Brianna Cagle
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, University of Iowa, Iowa City, IA, United States
| | - Coby Yeung
- Department of Chemistry, College of Arts and Sciences, Stony Brook University, Stony Brook, New York
| | - Xueshu Li
- Interdisciplinary Graduate Program in Human Toxicology and Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa
| | - Eric V Patterson
- Department of Chemistry, College of Arts and Sciences, Stony Brook University, Stony Brook, New York
| | - Jonathan A Doorn
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, University of Iowa, Iowa City, IA, United States
| | - Hans-Joachim Lehmler
- Interdisciplinary Graduate Program in Human Toxicology and Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa
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Li X, Wu X, Kelly KM, Veng-Pedersen P, Lehmler HJ. Toxicokinetics of Chiral PCB 136 and Its Hydroxylated Metabolites in Mice with a Liver-Specific Deletion of Cytochrome P450 Reductase. Chem Res Toxicol 2019; 32:727-736. [PMID: 30729780 DOI: 10.1021/acs.chemrestox.8b00389] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Exposure to polychlorinated biphenyls (PCBs) has been implicated in adverse human health effects, including developmental neurotoxicity. Several neurotoxic PCBs are chiral and undergo atropisomeric enrichment in vivo due to atropselective metabolism by cytochrome P450 enzymes. Here we study how the liver-specific deletion of the cytochrome P450 reductase ( cpr) gene alters the toxicokinetics of 2,2',3,3',6,6'-hexachlorobiphenyl (PCB 136) in mice. Male and female mice with a liver-specific deletion of cpr (KO) and congenic wild-type (WT) mice were exposed to a single oral dose of racemic PCB 136 (6.63 mg/kg). Levels and chiral signatures of PCB 136 and its hydroxylated metabolites were determined 1-48 h after PCB exposure in whole blood. Blood levels of PCB 136 were typically higher in M-WT compared to F-WT mice. At the later time points, F-KO mice had significantly higher PCB 136 levels than F-WT mice. 2,2',3',4,6,6'-Hexachlorobiphenyl-3-ol (3-150), 2,2',3,3',6,6'-hexachlorobiphenyl-4-ol (4-136), 2,2',3,3',6,6'-hexachlorobiphenyl-5-ol (5-136), and 4,5-dihydroxy-2,2',3,3',6,6'-hexachlorobiphenyl (4,5-136) were detected in blood, with 5-136 and 4-136 being major metabolites. At later time points, the sum of HO-PCB (∑HO-PCB) levels exceeded PCB 136 levels in the blood; however, higher ∑HO-PCB than PCB 136 levels were observed later in KO than WT mice. PCB 136 and its major metabolites displayed atropisomeric enrichment in a manner that depended on the time point, sex, and genotype. Toxicokinetic analysis revealed sex and genotype-dependent differences in toxicokinetic parameters for PCB 136 atropisomers and its metabolites. The results suggest that mice with a liver-specific deletion of the cpr gene can potentially be used to assess how an altered metabolism of neurotoxic PCB congeners affects neurotoxic outcomes following exposure of the offspring to PCBs via the maternal diet.
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Affiliation(s)
- Xueshu Li
- Department of Occupational and Environmental Health, College of Public Health , University of Iowa , Iowa City , Iowa 52242 , United States
| | - Xianai Wu
- Department of Occupational and Environmental Health, College of Public Health , University of Iowa , Iowa City , Iowa 52242 , United States
| | - Kevin M Kelly
- Department of Occupational and Environmental Health, College of Public Health , University of Iowa , Iowa City , Iowa 52242 , United States
| | - Peter Veng-Pedersen
- College of Pharmacy , University of Iowa , Iowa City , Iowa 52242 , United States
| | - Hans-Joachim Lehmler
- Department of Occupational and Environmental Health, College of Public Health , University of Iowa , Iowa City , Iowa 52242 , United States
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Uwimana E, Ruiz P, Li X, Lehmler HJ. Human CYP2A6, CYP2B6, AND CYP2E1 Atropselectively Metabolize Polychlorinated Biphenyls to Hydroxylated Metabolites. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:2114-2123. [PMID: 30576102 PMCID: PMC6380921 DOI: 10.1021/acs.est.8b05250] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Exposure to chiral polychlorinated biphenyls (PCBs) has been associated with neurodevelopmental disorders. Their hydroxylated metabolites (OH-PCBs) are also potentially toxic to the developing human brain; however, the formation of OH-PCBs by human cytochrome P450 (P450) isoforms is poorly investigated. To address this knowledge gap, we investigated the atropselective biotransformation of 2,2',3,4',6-pentachlorobiphenyl (PCB 91), 2,2',3,5',6-pentachlorobiphenyl (PCB 95), 2,2',3,3',4,6'-hexachlorobiphenyl (PCB 132), and 2,2',3,3',6,6'-hexachlorobiphenyl (PCB 136) by different human P450 isoforms. In silico predictions with ADMET Predictor and MetaDrug software suggested a role of CYP1A2, CYP2A6, CYP2B6, CYP2E1, and CYP3A4 in the metabolism of chiral PCBs. Metabolism studies with recombinant human enzymes demonstrated that CYP2A6 and CYP2B6 oxidized PCB 91 and PCB 132 in the meta position and that CYP2A6 oxidized PCB 95 and PCB 136 in the para position. CYP2B6 played only a minor role in the metabolism of PCB 95 and PCB 136 and formed meta-hydroxylated metabolites. Traces of para-hydroxylated PCB metabolites were detected in incubations with CYP2E1. No hydroxylated metabolites were present in incubations with CYP1A2 or CYP3A4. Atropselective analysis revealed P450 isoform-dependent and congener-specific atropselective enrichment of OH-PCB metabolites. These findings suggest that CYP2A6 and CYP2B6 play an important role in the oxidation of neurotoxic PCBs to chiral OH-PCBs in humans.
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Affiliation(s)
- Eric Uwimana
- Interdisciplinary Graduate Program in Human Toxicology and Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA 52242, United States
| | - Patricia Ruiz
- Division of Toxicology and Human Health Sciences, Computational Toxicology and Methods Development Lab, Agency for Toxic Substances and Disease Registry, Atlanta, GA 30333, United States
| | - Xueshu Li
- Interdisciplinary Graduate Program in Human Toxicology and Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA 52242, United States
| | - Hans-Joachim Lehmler
- Interdisciplinary Graduate Program in Human Toxicology and Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA 52242, United States
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10
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Pěnčíková K, Svržková L, Strapáčová S, Neča J, Bartoňková I, Dvořák Z, Hýžďalová M, Pivnička J, Pálková L, Lehmler HJ, Li X, Vondráček J, Machala M. In vitro profiling of toxic effects of prominent environmental lower-chlorinated PCB congeners linked with endocrine disruption and tumor promotion. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 237:473-486. [PMID: 29518658 PMCID: PMC5908724 DOI: 10.1016/j.envpol.2018.02.067] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 02/20/2018] [Accepted: 02/20/2018] [Indexed: 05/18/2023]
Abstract
The mechanisms contributing to toxic effects of airborne lower-chlorinated PCB congeners (LC-PCBs) remain poorly characterized. We evaluated in vitro toxicities of environmental LC-PCBs found in both indoor and outdoor air (PCB 4, 8, 11, 18, 28 and 31), and selected hydroxylated metabolites of PCB 8, 11 and 18, using reporter gene assays, as well as other functional cellular bioassays. We focused on processes linked with endocrine disruption, tumor promotion and/or regulation of transcription factors controlling metabolism of both endogenous compounds and xenobiotics. The tested LC-PCBs were found to be mostly efficient anti-androgenic (within nanomolar - micromolar range) and estrogenic (at micromolar concentrations) compounds, as well as inhibitors of gap junctional intercellular communication (GJIC) at micromolar concentrations. PCB 8, 28 and 31 were found to partially inhibit the aryl hydrocarbon receptor (AhR)-mediated activity. The tested LC-PCBs were also partial constitutive androstane receptor (CAR) and pregnane X receptor (PXR) agonists, with PCB 4, 8 and 18 being the most active compounds. They were inactive towards other nuclear receptors, such as vitamin D receptor, thyroid receptor α, glucocorticoid receptor or peroxisome proliferator-activated receptor γ. We found that only PCB 8 contributed to generation of oxidative stress, while all tested LC-PCBs induced arachidonic acid release (albeit without further modulations of arachidonic acid metabolism) in human lung epithelial cells. Importantly, estrogenic effects of hydroxylated (OH-PCB) metabolites of LC-PCBs (4-OH-PCB 8, 4-OH-PCB 11 and 4'-OH-PCB 18) were higher than those of the parent PCBs, while their other toxic effects were only slightly altered or suppressed. This suggested that metabolism may alter toxicity profiles of LC-PCBs in a receptor-specific manner. In summary, anti-androgenic and estrogenic activities, acute inhibition of GJIC and suppression of the AhR-mediated activity were found to be the most relevant modes of action of airborne LC-PCBs, although they partially affected also additional cellular targets.
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Affiliation(s)
- Kateřina Pěnčíková
- Department of Chemistry and Toxicology, Veterinary Research Institute, Hudcova 70, 62100 Brno, Czech Republic
| | - Lucie Svržková
- Department of Chemistry and Toxicology, Veterinary Research Institute, Hudcova 70, 62100 Brno, Czech Republic
| | - Simona Strapáčová
- Department of Chemistry and Toxicology, Veterinary Research Institute, Hudcova 70, 62100 Brno, Czech Republic
| | - Jiří Neča
- Department of Chemistry and Toxicology, Veterinary Research Institute, Hudcova 70, 62100 Brno, Czech Republic
| | - Iveta Bartoňková
- Department of Cell Biology and Genetics, Faculty of Science, Šlechtitelů 11, Palacký University, 78371 Olomouc, Czech Republic
| | - Zdeněk Dvořák
- Department of Cell Biology and Genetics, Faculty of Science, Šlechtitelů 11, Palacký University, 78371 Olomouc, Czech Republic
| | - Martina Hýžďalová
- Department of Chemistry and Toxicology, Veterinary Research Institute, Hudcova 70, 62100 Brno, Czech Republic; Department of Cytokinetics, Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 61265 Brno, Czech Republic
| | - Jakub Pivnička
- Department of Cytokinetics, Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 61265 Brno, Czech Republic
| | - Lenka Pálková
- Department of Chemistry and Toxicology, Veterinary Research Institute, Hudcova 70, 62100 Brno, Czech Republic
| | - Hans-Joachim Lehmler
- Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, 52242, IA, USA
| | - Xueshu Li
- Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, 52242, IA, USA
| | - Jan Vondráček
- Department of Cytokinetics, Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 61265 Brno, Czech Republic.
| | - Miroslav Machala
- Department of Chemistry and Toxicology, Veterinary Research Institute, Hudcova 70, 62100 Brno, Czech Republic.
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