1
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Simpson JB, Walker ME, Sekela JJ, Ivey SM, Jariwala PB, Storch CM, Kowalewski ME, Graboski AL, Lietzan AD, Walton WG, Davis KA, Cloer EW, Borlandelli V, Hsiao YC, Roberts LR, Perlman DH, Liang X, Overkleeft HS, Bhatt AP, Lu K, Redinbo MR. Gut microbial β-glucuronidases influence endobiotic homeostasis and are modulated by diverse therapeutics. Cell Host Microbe 2024; 32:925-944.e10. [PMID: 38754417 PMCID: PMC11176022 DOI: 10.1016/j.chom.2024.04.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 03/18/2024] [Accepted: 04/24/2024] [Indexed: 05/18/2024]
Abstract
Hormones and neurotransmitters are essential to homeostasis, and their disruptions are connected to diseases ranging from cancer to anxiety. The differential reactivation of endobiotic glucuronides by gut microbial β-glucuronidase (GUS) enzymes may influence interindividual differences in the onset and treatment of disease. Using multi-omic, in vitro, and in vivo approaches, we show that germ-free mice have reduced levels of active endobiotics and that distinct gut microbial Loop 1 and FMN GUS enzymes drive hormone and neurotransmitter reactivation. We demonstrate that a range of FDA-approved drugs prevent this reactivation by intercepting the catalytic cycle of the enzymes in a conserved fashion. Finally, we find that inhibiting GUS in conventional mice reduces free serotonin and increases its inactive glucuronide in the serum and intestines. Our results illuminate the indispensability of gut microbial enzymes in sustaining endobiotic homeostasis and indicate that therapeutic disruptions of this metabolism promote interindividual response variabilities.
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Affiliation(s)
- Joshua B Simpson
- Department of Chemistry, University of North Carolina, Chapel Hill, NC, USA
| | - Morgan E Walker
- Department of Chemistry, University of North Carolina, Chapel Hill, NC, USA
| | - Joshua J Sekela
- Department of Chemistry, University of North Carolina, Chapel Hill, NC, USA
| | - Samantha M Ivey
- Department of Chemistry, University of North Carolina, Chapel Hill, NC, USA
| | - Parth B Jariwala
- Department of Chemistry, University of North Carolina, Chapel Hill, NC, USA
| | - Cameron M Storch
- Department of Chemistry, University of North Carolina, Chapel Hill, NC, USA
| | - Mark E Kowalewski
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, USA
| | - Amanda L Graboski
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA
| | - Adam D Lietzan
- Division of Oral and Craniofacial Health Sciences, Adams School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - William G Walton
- Department of Chemistry, University of North Carolina, Chapel Hill, NC, USA
| | - Kacey A Davis
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, USA
| | - Erica W Cloer
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Valentina Borlandelli
- Department of Bioorganic Synthesis, Leiden Institute of Chemistry, Leiden University, Leiden, the Netherlands
| | - Yun-Chung Hsiao
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Lee R Roberts
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA
| | - David H Perlman
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA
| | - Xue Liang
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA
| | - Hermen S Overkleeft
- Department of Bioorganic Synthesis, Leiden Institute of Chemistry, Leiden University, Leiden, the Netherlands
| | - Aadra P Bhatt
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Division of Gastroenterology and Hepatology, Department of Medicine, Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kun Lu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Matthew R Redinbo
- Department of Chemistry, University of North Carolina, Chapel Hill, NC, USA; Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, USA.
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2
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Chandrasekaran A, Bentley K, McClanahan R, Nallani G. Effects of pethoxamid treatment on the disposition of thyroxine in rats. Toxicol Appl Pharmacol 2024; 487:116959. [PMID: 38734151 DOI: 10.1016/j.taap.2024.116959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 04/11/2024] [Accepted: 05/08/2024] [Indexed: 05/13/2024]
Abstract
Pethoxamid (PXA) is a chloroacetamide herbicide that works by inhibiting the germination of target weeds in crops. PXA is not a genotoxic agent, however, in a two-year chronic toxicity study, incidence of thyroid follicular cell hyperplasia was observed in male rats treated at a high dose. Many non-mutagenic chemicals, including agrochemicals are known to produce thyroid hyperplasia in rodents through a hepatic metabolizing enzyme induction mode of action (MoA). In this study, the effects of oral gavage PXA treatment at 300 mg/kg for 7 days on the disposition of intravenously (iv) administered radio-labeled thyroxine ([125I]-T4) was assessed in bile-duct cannulated (BDC) rats. Another group of animals were treated with phenobarbital (PB, 100 mg/kg), a known enzyme inducer, serving as a positive control. The results showed significant increase (p < 0.01) in the mean liver weights in the PB and PXA-treated groups relative to the control group. The serum total T4 radioactivity Cmax and AUC0-4 values for PB and PXA-treated groups were lower than for the control group, suggesting increased clearance from serum. The mean percentages of administered radioactivity excreted in bile were 7.96 ± 0.38%, 16.13 ± 5.46%, and 11.99 ± 2.80% for the control, PB and PXA groups, respectively, indicating increased clearance via the bile in the treated animals. These data indicate that PXA can perturb the thyroid hormone homeostasis in rats by increasing T4 elimination in bile, possibly through enzyme induction mechanism similar to PB. In contrast to humans, the lack of high affinity thyroid binding globulin (TBG) in rats perhaps results in enhanced metabolism of T4 by uridine diphosphate glucuronosyl transferase (UGT). Since this liver enzyme induction MoA for thyroid hyperplasia by PB is known to be rodent specific, PXA effects on thyroid can also be considered not relevant to humans. The data from this study also suggest that incorporating a BDC rat model to determine thyroid hormone disposition using [125I]-T4 is valuable in a thyroid mode of action analysis.
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Affiliation(s)
| | - Karin Bentley
- FMC Corporation, 2929 Walnut St, Philadelphia, PA, USA
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3
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Baze A, Wiss L, Horbal L, Biemel K, Asselin L, Richert L. Comparison of in vitro thyroxine (T4) metabolism between Wistar rat and human hepatocyte cultures. Toxicol In Vitro 2024; 96:105763. [PMID: 38142784 DOI: 10.1016/j.tiv.2023.105763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 10/24/2023] [Accepted: 12/05/2023] [Indexed: 12/26/2023]
Abstract
In vitro assays remain relatively new in exploring human relevance of liver, in particular nuclear receptor-mediated perturbations of the hypothalamus-pituitary-thyroid axis seen in rodents, mainly in the rat. Consistent with in vivo data, we confirm that thyroid hormone thyroxine metabolism was 9 times higher in primary rat hepatocytes (PRH) than in primary human hepatocytes (PHH) cultured in a 2D sandwich (2Dsw) configuration. In addition, thyroxine glucuronide (T4-G) was by far the major metabolite formed in both species (99.1% in PRH and 69.7% in PHH) followed by thyroxine sulfate (T4-S, 0.7% in PRH and 18.1% in PHH) and triiodothyronine/reverse triiodothyronine (T3/rT3, 0.2% in PRH and 12.2% in PHH). After a 7-day daily exposure to orphan receptor-mediated liver inducers, T4 metabolism was strongly increased in PRH, almost exclusively through increased T4-G formation. These results were consistent with the inductions of glucuronosyltransferase Ugt2b1 and canalicular transporter Mrp2. PHH also responded to activation of the three nuclear receptors, with mainly induction of glucuronosyltransferase UGT1A1 and canalicular transporter MRP2. Despite this, T4 disappearance rate and secreted T4 metabolites were only slightly increased in PHH. Overall, our data highlight that cryopreserved hepatocytes in 2Dsw culture allowing long-term exposure and species comparison are of major interest in improving liver-mediated human safety assessment.
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Affiliation(s)
- Audrey Baze
- KaLy-Cell SAS, 20A rue du Général Leclerc, 67115 Plobsheim, France
| | - Lucille Wiss
- KaLy-Cell SAS, 20A rue du Général Leclerc, 67115 Plobsheim, France
| | - Liliia Horbal
- Pharmacelsus GmbH, Science Park 2, 66123 Saarbrüken, Germany
| | - Klaus Biemel
- Pharmacelsus GmbH, Science Park 2, 66123 Saarbrüken, Germany
| | - Laure Asselin
- KaLy-Cell SAS, 20A rue du Général Leclerc, 67115 Plobsheim, France
| | - Lysiane Richert
- KaLy-Cell SAS, 20A rue du Général Leclerc, 67115 Plobsheim, France; Zylan SAS, 8 rue de la Haute Corniche, 67210 Obernai, France.
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4
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Stokar-Regenscheit N, Bell L, Berridge B, Rudmann D, Tagle D, Hargrove-Grimes P, Schaudien D, Hahn K, Kühnlenz J, Ashton RS, Tseng M, Reichelt M, Laing ST, Kiyota T, Chamanza R, Sura R, Tomlinson L. Complex In Vitro Model Characterization for Context of Use in Toxicologic Pathology: Use Cases by Collaborative Teams of Biologists, Bioengineers, and Pathologists. Toxicol Pathol 2024; 52:123-137. [PMID: 38888280 DOI: 10.1177/01926233241253811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
Complex in vitro models (CIVMs) offer the potential to increase the clinical relevance of preclinical efficacy and toxicity assessments and reduce the reliance on animals in drug development. The European Society of Toxicologic Pathology (ESTP) and Society for Toxicologic Pathology (STP) are collaborating to highlight the role of pathologists in the development and use of CIVM. Pathologists are trained in comparative animal medicine which enhances their understanding of mechanisms of human and animal diseases, thus allowing them to bridge between animal models and humans. This skill set is important for CIVM development, validation, and data interpretation. Ideally, diverse teams of scientists, including engineers, biologists, pathologists, and others, should collaboratively develop and characterize novel CIVM, and collectively assess their precise use cases (context of use). Implementing a morphological CIVM evaluation should be essential in this process. This requires robust histological technique workflows, image analysis techniques, and needs correlation with translational biomarkers. In this review, we demonstrate how such tissue technologies and analytics support the development and use of CIVM for drug efficacy and safety evaluations. We encourage the scientific community to explore similar options for their projects and to engage with health authorities on the use of CIVM in benefit-risk assessment.
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Affiliation(s)
- Nadine Stokar-Regenscheit
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Luisa Bell
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | | | | | - Danilo Tagle
- National Center for Advancing Translational Sciences/National Institutes of Health, Bethesda, Maryland, USA
| | - Passley Hargrove-Grimes
- National Center for Advancing Translational Sciences/National Institutes of Health, Bethesda, Maryland, USA
| | - Dirk Schaudien
- Fraunhofer Institute for Toxicology and Experimental Medicine, Hannover, Germany
| | - Kerstin Hahn
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Julia Kühnlenz
- Bayer SAS, CropScience, Pathology & Mechanistic Toxicology, Sophia Antipolis, France
| | - Randolph S Ashton
- University of Wisconsin-Madison, Madison, Wisconsin, USA
- Neurosetta LLC, Madison, Wisconsin, USA
| | - Min Tseng
- Genentech, South San Francisco, California, USA
| | | | | | | | | | | | - Lindsay Tomlinson
- Pfizer Inc., Drug Safety Research and Development, Cambridge, Massachusetts, USA
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5
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Wang Z, Haange SB, Haake V, Huisinga M, Kamp H, Buesen R, Schubert K, Canzler S, Hackermüller J, Rolle-Kampczyk U, Bergen MV. Assessing the Influence of Propylthiouracil and Phenytoin on the Metabolomes of the Thyroid, Liver, and Plasma in Rats. Metabolites 2023; 13:847. [PMID: 37512556 PMCID: PMC10383188 DOI: 10.3390/metabo13070847] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 06/26/2023] [Accepted: 07/06/2023] [Indexed: 07/30/2023] Open
Abstract
The thyroid hormones (THs) regulate various physiological mechanisms in mammals, such as cellular metabolism, cell structure, and membrane transport. The therapeutic drugs propylthiouracil (PTU) and phenytoin are known to induce hypothyroidism and decrease blood thyroid hormone levels. To analyze the impact of these two drugs on systemic metabolism, we focused on metabolic changes after treatment. Therefore, in a rat model, the metabolome of thyroid and liver tissue as well as from the blood plasma, after 2-week and 4-week administration of the drugs and after a following 2-week recovery phase, was investigated using targeted LC-MS/MS and GC-MS. Both drugs were tested at a low dose and a high dose. We observed decreases in THs plasma levels, and higher doses of the drugs were associated with a high decrease in TH levels. PTU administration had a more pronounced effect on TH levels than phenytoin. Both drugs had little or no influence on the metabolomes at low doses. Only PTU exhibited apparent metabolome alterations at high doses, especially concerning lipids. In plasma, acylcarnitines and triglycerides were detected at decreased levels than in the controls after 2- and 4-week exposure to the drug, while sphingomyelins and phosphatidylcholines were observed at increased levels. Interestingly, in the thyroid tissue, triglycerides were observed at increased concentrations in the 2-week exposure group to PTU, which was not observed in the 4-week exposure group and in the 4-week exposure group followed by the 2-week recovery group, suggesting an adaptation by the thyroid tissue. In the liver, no metabolites were found to have significantly changed. After the recovery phase, the thyroid, liver, and plasma metabolomic profiles showed little or no differences from the controls. In conclusion, although there were significant changes observed in several plasma metabolites in PTU/Phenytoin exposure groups, this study found that only PTU exposure led to adaptation-dependent changes in thyroid metabolites but did not affect hepatic metabolites.
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Affiliation(s)
- Zhipeng Wang
- Department of Molecular Systems Biology, Helmholtz-Centre for Environmental Research-UFZ, 04318 Leipzig, Germany
| | - Sven-Bastiaan Haange
- Department of Molecular Systems Biology, Helmholtz-Centre for Environmental Research-UFZ, 04318 Leipzig, Germany
| | - Volker Haake
- BASF Metabolome Solutions GmbH, 10589 Berlin, Germany
| | - Maike Huisinga
- Experimental Toxicology and Ecology, BASF SE, 67056 Ludwigshafen, Germany
| | - Hennicke Kamp
- BASF Metabolome Solutions GmbH, 10589 Berlin, Germany
| | - Roland Buesen
- Experimental Toxicology and Ecology, BASF SE, 67056 Ludwigshafen, Germany
| | - Kristin Schubert
- Department of Molecular Systems Biology, Helmholtz-Centre for Environmental Research-UFZ, 04318 Leipzig, Germany
| | - Sebastian Canzler
- Department of Computational Biology, Helmholtz-Centre for Environmental Research-UFZ, 04318 Leipzig, Germany
| | - Jörg Hackermüller
- Department of Computational Biology, Helmholtz-Centre for Environmental Research-UFZ, 04318 Leipzig, Germany
- Department of Computer Science, University of Leipzig, 04109 Leipzig, Germany
| | - Ulrike Rolle-Kampczyk
- Department of Molecular Systems Biology, Helmholtz-Centre for Environmental Research-UFZ, 04318 Leipzig, Germany
| | - Martin von Bergen
- Department of Molecular Systems Biology, Helmholtz-Centre for Environmental Research-UFZ, 04318 Leipzig, Germany
- Institute of Biochemistry, Faculty of Biosciences, Pharmacy and Psychology, University of Leipzig, 04103 Leipzig, Germany
- German Centre for Integrative Biodiversity Research, (iDiv) Halle-Jena-Leipzig, 04103 Leipzig, Germany
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6
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Melching-Kollmuss S, Bothe K, Charlton A, Gangadharan B, Ghaffari R, Jacobi S, Marty S, Marxfeld HA, McInnes EF, Sauer UG, Sheets LP, Strupp C, Tinwell H, Wiemann C, Botham PA, van Ravenzwaay B. Towards a science-based testing strategy to identify maternal thyroid hormone imbalance and neurodevelopmental effects in the progeny - Part IV: the ECETOC and CLE Proposal for a Thyroid Function-Related Neurodevelopmental Toxicity Testing and Assessment Scheme (Thyroid-NDT-TAS). Crit Rev Toxicol 2023; 53:339-371. [PMID: 37554099 DOI: 10.1080/10408444.2023.2231033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 06/22/2023] [Accepted: 06/22/2023] [Indexed: 08/10/2023]
Abstract
Following the European Commission Endocrine Disruptor Criteria, substances shall be considered as having endocrine disrupting properties if they (a) elicit adverse effects, (b) have endocrine activity, and (c) the two are linked by an endocrine mode-of-action (MoA) unless the MoA is not relevant for humans. A comprehensive, structured approach to assess whether substances meet the Endocrine Disruptor Criteria for the thyroid modality (EDC-T) is currently unavailable. Here, the European Centre for Ecotoxicology and Toxicology of Chemicals Thyroxine Task Force and CropLife Europe propose a Thyroid Function-Related Neurodevelopmental Toxicity Testing and Assessment Scheme (Thyroid-NDT-TAS). In Tier 0, before entering the Thyroid-NDT-TAS, all available in vivo, in vitro and in silico data are submitted to weight-of-evidence (WoE) evaluations to determine whether the substance of interest poses a concern for thyroid disruption. If so, Tier 1 of the Thyroid-NDT-TAS includes an initial MoA and human relevance assessment (structured by the key events of possibly relevant adverse outcome pathways) and the generation of supportive in vitro/in silico data, if relevant. Only if Tier 1 is inconclusive, Tier 2 involves higher-tier testing to generate further thyroid- and/or neurodevelopment-related data. Tier 3 includes the final MoA and human relevance assessment and an overarching WoE evaluation to draw a conclusion on whether, or not, the substance meets the EDC-T. The Thyroid-NDT-TAS is based on the state-of-the-science, and it has been developed to minimise animal testing. To make human safety assessments more accurate, it is recommended to apply the Thyroid-NDT-TAS during future regulatory assessments.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Ursula G Sauer
- Scientific Consultancy - Animal Welfare, Neubiberg, Germany
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7
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Proença S, van Sabben N, Legler J, Kamstra JH, Kramer NI. The effects of hexabromocyclododecane on the transcriptome and hepatic enzyme activity in three human HepaRG-based models. Toxicology 2023; 485:153411. [PMID: 36572169 DOI: 10.1016/j.tox.2022.153411] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 12/09/2022] [Accepted: 12/21/2022] [Indexed: 12/24/2022]
Abstract
The disruption of thyroid hormone homeostasis by hexabromocyclododecane (HBCD) in rodents is hypothesized to be due to HBCD increasing the hepatic clearance of thyroxine (T4). The extent to which these effects are relevant to humans is unclear. To evaluate HBCD effects on humans, the activation of key hepatic nuclear receptors and the consequent disruption of thyroid hormone homeostasis were studied in different human hepatic cell models. The hepatoma cell line, HepaRG, cultured as two-dimensional (2D), sandwich (SW) and spheroid (3D) cultures, and primary human hepatocytes (PHH) cultured as sandwich were exposed to 1 and 10 µM HBCD and characterized for their transcriptome changes. Pathway enrichment analysis showed that 3D models, followed by SW, had a stronger transcriptome response to HBCD, which is explained by the higher expression of hepatic nuclear receptors but also greater accumulation of HBCD measured inside cells in these models. The Pregnane X receptor pathway is one of the pathways most upregulated across the three hepatic models, followed by the constitutive androstane receptor and general hepatic nuclear receptors pathways. Lipid metabolism pathways had a downregulation tendency in all exposures and in both PHH and the three cultivation modes of HepaRG. The activity of enzymes related to PXR/CAR induction and T4 metabolism were evaluated in the three different types of HepaRG cultures exposed to HBCD for 48 h. Reference inducers, rifampicin and PCB-153 did affect 2D and SW HepaRG cultures' enzymatic activity but not 3D. HBCD did not induce the activity of any of the studied enzymes in any of the cell models and culture methods. This study illustrates that for nuclear receptor-mediated T4 disruption, transcriptome changes might not be indicative of an actual adverse effect. Clarification of the reasons for the lack of translation is essential to evaluate new chemicals' potential to be thyroid hormone disruptors by altering thyroid hormone metabolism.
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Affiliation(s)
- Susana Proença
- Department of Toxicology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands; Toxicology Division, Wageningen University, Wageningen, the Netherlands.
| | - Nick van Sabben
- Department of Toxicology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands
| | - Juliette Legler
- Department of Toxicology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands
| | - Jorke H Kamstra
- Department of Toxicology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands
| | - Nynke I Kramer
- Department of Toxicology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands; Toxicology Division, Wageningen University, Wageningen, the Netherlands
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8
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Parmentier C, Baze A, Untrau M, Kampkoetter A, Lasserre D, Richert L. Evaluation of human relevance of Nicofluprole-induced rat thyroid disruption. Toxicol Appl Pharmacol 2021; 435:115831. [PMID: 34922950 DOI: 10.1016/j.taap.2021.115831] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/08/2021] [Accepted: 12/13/2021] [Indexed: 10/19/2022]
Abstract
Nicofluprole is a novel insecticide of the phenylpyrazole class conferring selective antagonistic activity on insect GABA receptors. After repeated daily dietary administration to Wistar rats for 28/90 days, Nicofluprole induced increases in thyroid (and liver) weight, associated with histopathology changes. Nicofluprole did not inhibit thyroid peroxydase nor sodium/iodide symporter, two key players in the biosynthesis of thyroid hormones, indicating the absence of a direct thyroid effect. The results seen in rats suggested a mode of action of Nicofluprole driven by the molecular initiating event of CAR/PXR nuclear receptor activation in livers, with key events of increases in liver weight and hypertrophy, decreasing circulatory thyroid hormones, a compensatory increase in TSH release and follicular cell hypertrophy. To explore the relevance of these changes to humans, well established in vitro rat and human sandwich-cultured hepatocytes were exposed to Nicofluprole up to 7 days. A concentration-dependent CYP3A induction (PXR-activation), an increase in T4-glucuronoconjugation accompanied by UGT1A/2B inductions was observed in rat but not in human hepatocytes. The inductions seen with Nicofluprole in rat (in vivo and in vitro in hepatocytes) that were absent in human hepatocytes represent another example of species-selectivity of nuclear CAR/PXR receptor activators. Importantly, the different pattern observed in rat and human models demonstrate that Nicofluprole-related thyroid effects observed in the rat are with no human relevance.
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Affiliation(s)
- Céline Parmentier
- KaLy-Cell S.A.S, 20A rue du Général Leclerc, 67115 Plobsheim, France.
| | - Audrey Baze
- KaLy-Cell S.A.S, 20A rue du Général Leclerc, 67115 Plobsheim, France.
| | - Meiggie Untrau
- KaLy-Cell S.A.S, 20A rue du Général Leclerc, 67115 Plobsheim, France
| | - Andreas Kampkoetter
- Bayer Animal Health GmbH, An Elanco Animal Health Company, 50 Alfred-Nobel-Strasse, 40789 Monheim, Germany.
| | - Dominique Lasserre
- Bayer S.A.S. Bayer CropScience, 355 rue Dostoïevski, F-06560 Sophia Antipolis, France.
| | - Lysiane Richert
- KaLy-Cell S.A.S, 20A rue du Général Leclerc, 67115 Plobsheim, France.
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Abstract
The thyroid hormone system is a main target of endocrine disruptor compounds (EDC) at all levels of its intricately fine-tuned feedback regulation, synthesis, distribution, metabolism and action of the 'prohormone' thyroxine and its active metabolites. Apart from classical antithyroid effects of EDC on the gland, the majority of known and suspected effects occurs at the pre-receptor control of T3 ligand availability to T3 receptors exerting ligand modulated thyroid hormone action. Tissue-, organ- and cell-specific expression and function of thyroid hormone transporters, deiodinases, metabolizing enzymes and T3-receptor forms, all integral components of the system, may mediate adverse EDC effects. Established evidence from nutritional, pharmacological and molecular genetic studies clearly support the functional, biological, and clinical relevance of these targets. Iodine-containing thyroid hormones and the organization of this system are highly conserved during evolution from primitive aquatic life forms, amphibia, birds throughout all vertebrates including humans. Mechanistic studies from various animal experimental models strongly support cause-effect relationships upon EDC exposure, hazards and adverse effects of EDC across various species. Retrospective case-control, cohort and population studies linking EDC exposure with epidemiological data on thyroid hormone-related (dys-)functions provide clear evidence that human development, especially of the fetal and neonatal brain, growth, differentiation and metabolic processes in adult and aging humans are at risk for adverse EDC effects. Considering that more than half of the world population still lives on inadequate iodine supply, the additional ubiquitous exposure to EDC and their mixtures is an additional threat for the essential thyroid hormone system, the health of the human population and their future progenies, animal life forms and our global environment.
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Affiliation(s)
- Josef Köhrle
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institut für Experimentelle Endokrinologie, Hessische Strasse 3-4, 10115, Berlin, Germany.
| | - Caroline Frädrich
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institut für Experimentelle Endokrinologie, Hessische Strasse 3-4, 10115, Berlin, Germany
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10
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Marty S, Beekhuijzen M, Charlton A, Hallmark N, Hannas BR, Jacobi S, Melching-Kollmuss S, Sauer UG, Sheets LP, Strauss V, Urbisch D, Botham PA, van Ravenzwaay B. Towards a science-based testing strategy to identify maternal thyroid hormone imbalance and neurodevelopmental effects in the progeny - part II: how can key events of relevant adverse outcome pathways be addressed in toxicological assessments? Crit Rev Toxicol 2021; 51:328-358. [PMID: 34074207 DOI: 10.1080/10408444.2021.1910625] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The current understanding of thyroid-related adverse outcome pathways (AOPs) with adverse neurodevelopmental outcomes in mammals has been reviewed. This served to establish if standard rodent toxicity test methods and in vitro assays allow identifying thyroid-related modes-of-action potentially leading to adverse neurodevelopmental outcomes, and the human relevance of effects - in line with the European Commission's Endocrine Disruptor Criteria. The underlying hypothesis is that an understanding of the key events of relevant AOPs provides insight into differences in incidence, magnitude, or species sensitivity of adverse outcomes. The rodent studies include measurements of serum thyroid hormones, thyroid gland pathology and neurodevelopmental assessments, but do not directly inform on specific modes-of-action. Opportunities to address additional non-routine parameters reflecting critical events of AOPs in toxicological assessments are presented. These parameters appear relevant to support the identification of specific thyroid-related modes-of-action, provided that prevailing technical limitations are overcome. Current understanding of quantitative key event relationships is often weak, but would be needed to determine if the triggering of a molecular initiating event will ultimately result in an adverse outcome. Also, significant species differences in all processes related to thyroid hormone signalling are evident, but the biological implications thereof (including human relevance) are often unknown. In conclusion, careful consideration of the measurement (e.g. timing, method) and interpretation of additional non-routine parameters is warranted. These findings will be used in a subsequent paper to propose a testing strategy to identify if a substance may elicit maternal thyroid hormone imbalance and potentially also neurodevelopmental effects in the progeny.
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Affiliation(s)
- Sue Marty
- The Dow Chemical Company, Midland, MI, USA
| | | | | | | | | | | | | | - Ursula G Sauer
- Scientific Consultancy - Animal Welfare, Neubiberg, Germany
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11
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Bomann W, Tinwell H, Jenkinson P, Kluxen FM. Metribuzin-induced non-adverse liver changes result in rodent-specific non-adverse thyroid effects via uridine 5'-diphospho-glucuronosyltransferase (UDPGT, UGT) modulation. Regul Toxicol Pharmacol 2021; 122:104884. [PMID: 33596450 DOI: 10.1016/j.yrtph.2021.104884] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 01/19/2021] [Accepted: 02/01/2021] [Indexed: 11/18/2022]
Abstract
Metribuzin is a herbicide that inhibits photosynthesis and has been used for over 40 years. Its main target organ is the liver and to some extent the kidney in rats, dogs, and rabbits. Metribuzin shows a specific thyroxine (T4) profile in rat studies with T4 increases at low doses and T4 decreases at higher doses. Only the T4 decreases occur together with histopathological changes in the thyroid and weight changes of liver and thyroid. A set of experiments was conducted to investigate metribuzin's endocrine disruptor potential according to European guidance and regulations. The results indicate that a liver enzyme modulation, i.e. of the uridine 5'-diphospho-glucuronosyltransferase (UDPGT, UGT), is most likely responsible for both increased and decreased plasma thyroxine level and for thyroid histopathological observations. Animals with high T4 levels show low UGT activity, while animals with low T4 levels show high UGT activity. A causal relationship was inferred, since other potentially human-relevant mode of action (MOA) pathways were excluded in dedicated studies, i.e. inhibition of deiodinases (DIO), inhibition of thyroid peroxidase (TPO) or of the sodium importer system (NIS). This liver metabolism-associated MOA is considered not relevant for human hazard assessment, due to species differences in thyroid homeostasis between humans and rats and, more importantly, based on experimental data showing that metribuzin affects UGT activity in rat but not in human hepatocytes. Further, we discuss whether or not increased T4 levels in the rat, in the absence of histopathological changes, should be considered as adverse and therefore used as an appropriate hazard model for humans. Based on a weight of evidence approach, metribuzin should not be classified as an endocrine disruptor with regard to the thyroid modality.
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Affiliation(s)
- Werner Bomann
- Toxconsult, 9393 W 110th Street, 51 Corporate Woods, Suite 500, Overland Park, KS, 66210, USA.
| | - Helen Tinwell
- Bayer.SAS, 16 rue Jean-Marie Leclair, 69009, Lyon, France
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12
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Plummer S, Beaumont B, Elcombe M, Wallace S, Wright J, Mcinnes EF, Currie RA, Cowie D. Species differences in phenobarbital-mediated UGT gene induction in rat and human liver microtissues. Toxicol Rep 2021; 8:155-161. [PMID: 33473352 PMCID: PMC7803626 DOI: 10.1016/j.toxrep.2020.12.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 11/11/2020] [Accepted: 12/21/2020] [Indexed: 11/29/2022] Open
Abstract
Species differences in UGT induction could mediate thyroid cancer susceptibility. The effect of CAR activators on rat thyroid carcinogenesis could be partly explained by differential induction of Ugt 2b17. Human UGT changes would likely contribute less to species differences in T4 metabolism than rat UGT changes.
Species differences in hepatic metabolism of thyroxine (T4) by uridine diphosphate glucuronosyl transferase (UGT) and susceptibility to thyroid hormone imbalance could underlie differences in thyroid carcinogenesis caused by hepatic enzyme inducers in rats and humans. To investigate this hypothesis we examined profiles of hepatic UGT induction by the prototypical CAR activator phenobarbital (PB) in rat and human liver 3D microtissues. The rationale for this approach was that 3D microtissues would generate data more relevant to humans. Rat and human liver 3D microtissues were exposed to PB over a range of concentrations (500 u M - 2000 u M) and times (24−96 hr). Microarray and proteomics analyses were performed on parallel samples to generate integrated differentially expressed gene (DEG) datasets. Bioinformatics analysis of DEG data, including CAR response element (CRE) sequence analysis of UGT promoters, was used to assess species differences in UGT induction relative to CAR-mediated transactivation potential. A higher proportion of human UGT promoters were found to contain consensus CREs compared to the rat homologs. UGTs 1a6, 2b17 and 2b37 were upregulated by PB in rat liver 3D microtissues, but unaltered in human liver 3D microtissues. By contrast, human UGTs 1A8, 1A10 and 2B10 showed higher levels of induction (RNA and /or protein) compared to the rat homologs. There was general concordance between the presence of CREs and the induction of UGT RNA. As UGT1A and 2B isoforms metabolise T4, these results suggest that differences in UGT induction could contribute to differential susceptibility to CAR-mediated thyroid carcinogenesis in rats and humans.
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13
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A review of species differences in the control of, and response to, chemical-induced thyroid hormone perturbations leading to thyroid cancer. Arch Toxicol 2021; 95:807-836. [PMID: 33398420 DOI: 10.1007/s00204-020-02961-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 11/26/2020] [Indexed: 12/13/2022]
Abstract
This review summarises the current state of knowledge regarding the physiology and control of production of thyroid hormones, the effects of chemicals in perturbing their synthesis and release that result in thyroid cancer. It does not consider the potential neurodevelopmental consequences of low thyroid hormones. There are a number of known molecular initiating events (MIEs) that affect thyroid hormone synthesis in mammals and many chemicals are able to activate multiple MIEs simultaneously. AOP analysis of chemical-induced thyroid cancer in rodents has defined the key events that predispose to the development of rodent cancer and many of these will operate in humans under appropriate conditions, if they were exposed to high enough concentrations of the affecting chemicals. There are conditions however that, at the very least, would indicate significant quantitative differences in the sensitivity of humans to these effects, with rodents being considerably more sensitive to thyroid effects by virtue of differences in the biology, transport and control of thyroid hormones in these species as opposed to humans where turnover is appreciably lower and where serum transport of T4/T3 is different to that operating in rodents. There is heated debate around claimed qualitative differences between the rodent and human thyroid physiology, and significant reservations, both scientific and regulatory, still exist in terms of the potential neurodevelopmental consequences of low thyroid hormone levels at critical windows of time. In contrast, the situation for the chemical induction of thyroid cancer, through effects on thyroid hormone production and release, is less ambiguous with both theoretical, and actual data, showing clear dose-related thresholds for the key events predisposing to chemically induced thyroid cancer in rodents. In addition, qualitative differences in transport, and quantitative differences in half life, catabolism and turnover of thyroid hormones, exist that would not operate under normal situations in humans.
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14
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Strupp C, Quesnot N, Weber-Parmentier C, Richert L, Bomann WH, Singh P. Weight of Evidence and Human Relevance Evaluation of the Benfluralin Mode of Action in Rats (Part II): Thyroid carcinogenesis. Regul Toxicol Pharmacol 2020; 117:104736. [PMID: 32798613 DOI: 10.1016/j.yrtph.2020.104736] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 07/10/2020] [Accepted: 07/13/2020] [Indexed: 11/08/2022]
Abstract
Benfluralin is an herbicide of the dinitroaniline class used to control grasses and weeds. In a 2 year dietary study in rats, benfluralin increased incidences of thyroid follicular adenoma and carcinoma at high dietary concentrations (≥2500 ppm). The benfluralin toxicology database suggests the mode of action (MOA) is initiated by induction of liver metabolizing enzymes, particularly thyroid hormone specific UGTs, a major pathway for T4 clearance in rats. As reported with phenobarbital, this effect triggers negative feedback regulation, increasing thyroid stimulating hormone (TSH) release into circulating blood. When sustained over time, this leads to thyroid changes such as follicular hypertrophy, hyperplasia and thyroid follicular tumors with chronic exposures. The described MOA was previously established in rat studies with various chemical activators of xenobiotic receptors in the liver. It is generally considered as non-relevant in humans, due to differences between humans and rats in T4 turnover and susceptibility to this carcinogenic MOA. A structured methodology based on the IPCS/MOA/Human Relevance framework was used in the evaluation of available benfluralin data, and the conclusion was determined that the carcinogenic potential of benfluralin in the thyroid is not relevant in humans.
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Affiliation(s)
- Christian Strupp
- Gowan, Highlands House, Basingstoke Road, Spencers Wood Reading, Berkshire, RG7 1NT, United Kingdom.
| | - Nicolas Quesnot
- Charles River Laboratories Evreux, 27005, Evreux Cedex, France.
| | | | | | - Werner H Bomann
- ToxConsult®, 9393 W 110th Street, 51 Corporate Woods, Suite 500, Overland Park, KS, 66210, USA.
| | - Pramila Singh
- Charles River Laboratories Evreux, 27005, Evreux Cedex, France.
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15
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Li AA, Makris SL, Marty MS, Strauss V, Gilbert ME, Blacker A, Zorrilla LM, Coder PS, Hannas B, Lordi S, Schneider S. Practical considerations for developmental thyroid toxicity assessments: What's working, what's not, and how can we do better? Regul Toxicol Pharmacol 2019; 106:111-136. [PMID: 31018155 DOI: 10.1016/j.yrtph.2019.04.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 04/11/2019] [Accepted: 04/14/2019] [Indexed: 12/26/2022]
Abstract
Thyroid hormones (THs; T3 and T4) play a role in development of cardiovascular, reproductive, immune and nervous systems. Thus, interpretation of TH changes from rodent studies (during pregnancy, in fetuses, neonates, and adults) is critical in hazard characterization and risk assessment. A roundtable session at the 2017 Society of Toxicology (SOT) meeting brought together academic, industry and government scientists to share knowledge and different perspectives on technical and data interpretation issues. Data from a limited group of laboratories were compiled for technical discussions on TH measurements, including good practices for reliable serum TH data. Inter-laboratory historical control data, derived from immunoassays or mass spectrometry methods, revealed: 1) assay sensitivities vary within and across methodologies; 2) TH variability is similar across animal ages; 3) laboratories generally achieve sufficiently sensitive TH quantitation levels, although issues remain for lower levels of serum TH and TSH in fetuses and postnatal day 4 pups; thus, assay sensitivity is critical at these life stages. Best practices require detailed validation of rat serum TH measurements across ages to establish assay sensitivity and precision, and identify potential matrix effects. Finally, issues related to data interpretation for biological understanding and risk assessment were discussed, but their resolution remains elusive.
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Affiliation(s)
- Abby A Li
- Exponent Inc., 1010 14th Street, San Francisco, CA, 94114, USA.
| | - Susan L Makris
- US Environmental Protection Agency Office of Research and Development, 1200 Pennsylvania Ave NW 8623R, Washington, DC, 20460, USA.
| | - M Sue Marty
- The Dow Chemical Company, Toxicology & Environmental Research and Consulting, 1803 Building, Midland, MI, 48674, USA.
| | - Volker Strauss
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen, Germany.
| | - Mary E Gilbert
- US Environmental Protection Agency, National Health Environmental Effects Research Lab, 109 T.W. Alexander Drive, MD B105 05, Research Triangle Park, NC, 27711, USA.
| | - Ann Blacker
- Bayer CropScience, P.O. Box 12014, RTP, NC, 27709, USA.
| | | | - Pragati S Coder
- Charles River Laboratories, Developmental and Reproductive Toxicology, 1407 George Road, Ashland, OH, 44805, USA.
| | - Bethany Hannas
- The Dow Chemical Company, Toxicology & Environmental Research and Consulting, 1803 Building, Midland, MI, 48674, USA.
| | - Sheri Lordi
- Charles River Laboratories International, 251 Ballardvale Street, Wilmington, MA, 01887, USA.
| | - Steffen Schneider
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen, Germany.
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16
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Characterization of non-radiolabeled Thyroxine (T 4) uptake in cryopreserved rat hepatocyte suspensions: Pharmacokinetic implications for PFOA and PFOS chemical exposure. Toxicol In Vitro 2019; 58:230-238. [PMID: 30930230 DOI: 10.1016/j.tiv.2019.03.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 02/28/2019] [Accepted: 03/18/2019] [Indexed: 11/22/2022]
Abstract
The alteration of thyroxine (T4) cellular uptake by an environmental chemical can serve as a contributing factor in thyroid hormone (TH) disruption. Herein, we describe a non-radiolabeled (LC-MS/MS) oil-filtration technique designed to characterize the mechanism(s) responsible for T4 cellular uptake in cryopreserved rat hepatocyte suspensions. The environmental chemicals perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) were evaluated for their effect on T4 hepatic uptake. At 37 °C, hepatic assays demonstrated saturable kinetics with increasing T4 concentrations, while a linear uptake rate consistent with passive diffusion was detected at 4 °C. Carrier-mediated (37-4 °C) transport of T4 was the predominant hepatic uptake process versus passive diffusion. Cyclosporin A (CsA) chemically inhibited T4 hepatic uptake, whereas PFOA/PFOS displayed no inhibition of T4 translocation. Increasing PFOA/PFOS concentration levels with the T4 serum carrier-protein transthyretin (TTR) present resulted in a dose-response increase in T4 hepatic uptake rates, correlating with increased T4 free fraction values. Hepatic assays conducted in the presence of PFOA/PFOS and TTR displayed an enhanced first-order T4 hepatic uptake rate consistent with carrier-mediated transport. These in vitro findings characterizing increased T4 hepatic uptake provides mechanistic insight regarding decreased T4 serum levels (hypothyroxinemia) previously observed within in vivo rodent studies following perfluorinated chemical exposure.
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17
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Knutsen HK, Alexander J, Barregård L, Bignami M, Brüschweiler B, Ceccatelli S, Cottrill B, Dinovi M, Edler L, Grasl-Kraupp B, Hogstrand C, Nebbia CS, Oswald IP, Petersen A, Rose M, Roudot AC, Schwerdtle T, Vleminckx C, Vollmer G, Wallace H, Fürst P, Håkansson H, Halldorsson T, Lundebye AK, Pohjanvirta R, Rylander L, Smith A, van Loveren H, Waalkens-Berendsen I, Zeilmaker M, Binaglia M, Gómez Ruiz JÁ, Horváth Z, Christoph E, Ciccolallo L, Ramos Bordajandi L, Steinkellner H, Hoogenboom LR. Risk for animal and human health related to the presence of dioxins and dioxin-like PCBs in feed and food. EFSA J 2018; 16:e05333. [PMID: 32625737 PMCID: PMC7009407 DOI: 10.2903/j.efsa.2018.5333] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The European Commission asked EFSA for a scientific opinion on the risks for animal and human health related to the presence of dioxins (PCDD/Fs) and DL-PCBs in feed and food. The data from experimental animal and epidemiological studies were reviewed and it was decided to base the human risk assessment on effects observed in humans and to use animal data as supportive evidence. The critical effect was on semen quality, following pre- and postnatal exposure. The critical study showed a NOAEL of 7.0 pg WHO2005-TEQ/g fat in blood sampled at age 9 years based on PCDD/F-TEQs. No association was observed when including DL-PCB-TEQs. Using toxicokinetic modelling and taking into account the exposure from breastfeeding and a twofold higher intake during childhood, it was estimated that daily exposure in adolescents and adults should be below 0.25 pg TEQ/kg bw/day. The CONTAM Panel established a TWI of 2 pg TEQ/kg bw/week. With occurrence and consumption data from European countries, the mean and P95 intake of total TEQ by Adolescents, Adults, Elderly and Very Elderly varied between, respectively, 2.1 to 10.5, and 5.3 to 30.4 pg TEQ/kg bw/week, implying a considerable exceedance of the TWI. Toddlers and Other Children showed a higher exposure than older age groups, but this was accounted for when deriving the TWI. Exposure to PCDD/F-TEQ only was on average 2.4- and 2.7-fold lower for mean and P95 exposure than for total TEQ. PCDD/Fs and DL-PCBs are transferred to milk and eggs, and accumulate in fatty tissues and liver. Transfer rates and bioconcentration factors were identified for various species. The CONTAM Panel was not able to identify reference values in most farm and companion animals with the exception of NOAELs for mink, chicken and some fish species. The estimated exposure from feed for these species does not imply a risk.
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18
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Dingemans MML, Kock M, van den Berg M. Mechanisms of Action Point Towards Combined PBDE/NDL-PCB Risk Assessment. Toxicol Sci 2018; 153:215-24. [PMID: 27672163 DOI: 10.1093/toxsci/kfw129] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
At present, human risk assessment of the structurally similar non-dioxin-like (NDL) PCBs and polybrominated diphenylethers (PBDEs) is done independently for both groups of compounds. There are however obvious similarities between NDL-PCBs and PBDEs with regard to modulation of the intracellular calcium homeostasis (basal calcium levels, voltage-gated calcium channels, calcium uptake, ryanodine receptor) and thyroid hormone (TH) homeostasis (TH levels and transport). which are mechanisms of action related to neurobehavioral effects (spontaneous activity, habituation and learning ability). There also similarities in agonistic interactions with the hepatic nuclear receptors PXR and CAR. Several effects on developmental (reproductive) processes have also been observed, but results were more dispersed and insufficient to compare both groups of compounds. The available mechanistic information is sufficient to warrant a dose addition model for NDL-PCBs and PBDEs, including their hydroxylated metabolites.Although many of the observed effects are similar from a qualitative point of view for both groups, congener or tissue specific differences have also been found. As this is a source of uncertainty in the combined hazard and risk assessment of these compounds, molecular entities involved in the observed mechanisms and adverse outcomes associated with these compounds need to be identified. The systematical generation of (quantitative) structure-activity information for NDL-PCBs and PBDEs on these targets (including potential non-additive effects) will allow a more realistic risk estimation associated with combined exposure to both groups of compounds during early life. Additional validation studies are needed to quantify these uncertainties for risk assessment of NDL-PCBs and PBDEs.
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Affiliation(s)
- Milou M L Dingemans
- Institute for Risk Assessment Sciences (IRAS), Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Marjolijn Kock
- Institute for Risk Assessment Sciences (IRAS), Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Martin van den Berg
- Institute for Risk Assessment Sciences (IRAS), Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
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19
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van der Spek AH, Fliers E, Boelen A. The classic pathways of thyroid hormone metabolism. Mol Cell Endocrinol 2017; 458:29-38. [PMID: 28109953 DOI: 10.1016/j.mce.2017.01.025] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 12/21/2016] [Accepted: 01/17/2017] [Indexed: 12/15/2022]
Abstract
Thyroid hormones (TH) are crucial for growth and development and play an important role in energy homeostasis. Although serum TH levels are relatively constant in the physiological state, TH bioavailability at the tissue and cellular level is dependent on local TH metabolism. Circulating TH produced by the thyroid can be metabolized by a number of different pathways resulting in 1) activation of TH 2) deactivation of TH or 3) excretion of TH and subsequent metabolites. These pathways play an essential role in determining local TH levels and action. The major classical pathways of TH metabolism are deiodination, sulfation, glucuronidation, and ether-link cleavage. This review provides an overview of these pathways, their relative contributions to TH levels in the serum and in various organs and the changes in these pathways elicited by fasting and illness.
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Affiliation(s)
- Anne H van der Spek
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Eric Fliers
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Anita Boelen
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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20
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Paul Friedman K, Papineni S, Marty MS, Yi KD, Goetz AK, Rasoulpour RJ, Kwiatkowski P, Wolf DC, Blacker AM, Peffer RC. A predictive data-driven framework for endocrine prioritization: a triazole fungicide case study. Crit Rev Toxicol 2016; 46:785-833. [PMID: 27347635 PMCID: PMC5044773 DOI: 10.1080/10408444.2016.1193722] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 05/13/2016] [Accepted: 05/21/2016] [Indexed: 10/27/2022]
Abstract
The US Environmental Protection Agency Endocrine Disruptor Screening Program (EDSP) is a tiered screening approach to determine the potential for a chemical to interact with estrogen, androgen, or thyroid hormone systems and/or perturb steroidogenesis. Use of high-throughput screening (HTS) to predict hazard and exposure is shifting the EDSP approach to (1) prioritization of chemicals for further screening; and (2) targeted use of EDSP Tier 1 assays to inform specific data needs. In this work, toxicology data for three triazole fungicides (triadimefon, propiconazole, and myclobutanil) were evaluated, including HTS results, EDSP Tier 1 screening (and other scientifically relevant information), and EPA guideline mammalian toxicology study data. The endocrine-related bioactivity predictions from HTS and information that satisfied the EDSP Tier 1 requirements were qualitatively concordant. Current limitations in the available HTS battery for thyroid and steroidogenesis pathways were mitigated by inclusion of guideline toxicology studies in this analysis. Similar margins (3-5 orders of magnitude) were observed between HTS-predicted human bioactivity and exposure values and between in vivo mammalian bioactivity and EPA chronic human exposure estimates for these products' registered uses. Combined HTS hazard and human exposure predictions suggest low priority for higher-tiered endocrine testing of these triazoles. Comparison with the mammalian toxicology database indicated that this HTS-based prioritization would have been protective for any potential in vivo effects that form the basis of current risk assessment for these chemicals. This example demonstrates an effective, human health protective roadmap for EDSP evaluation of pesticide active ingredients via prioritization using HTS and guideline toxicology information.
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Affiliation(s)
| | - Sabitha Papineni
- Human Health Assessment, Dow AgroSciences LLC,
Indianapolis,
IN,
USA
| | - M. Sue Marty
- Toxicology & Environmental Research and Consulting, The Dow Chemical Company,
Midland,
MI,
USA
| | - Kun Don Yi
- Toxicology and Health Sciences, Syngenta Crop Protection LLC,
Greensboro,
NC,
USA
| | - Amber K. Goetz
- Toxicology and Health Sciences, Syngenta Crop Protection LLC,
Greensboro,
NC,
USA
| | | | - Pat Kwiatkowski
- Human Safety, Bayer CropScience LP, Research Triangle Park,
NC,
USA
| | - Douglas C. Wolf
- Toxicology and Health Sciences, Syngenta Crop Protection LLC,
Greensboro,
NC,
USA
| | - Ann M. Blacker
- Human Safety, Bayer CropScience LP, Research Triangle Park,
NC,
USA
| | - Richard C. Peffer
- Toxicology and Health Sciences, Syngenta Crop Protection LLC,
Greensboro,
NC,
USA
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21
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Hirashima R, Michimae H, Takemoto H, Sasaki A, Kobayashi Y, Itoh T, Tukey RH, Fujiwara R. Induction of the UDP-Glucuronosyltransferase 1A1 during the Perinatal Period Can Cause Neurodevelopmental Toxicity. Mol Pharmacol 2016; 90:265-74. [PMID: 27413119 DOI: 10.1124/mol.116.104174] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 07/11/2016] [Indexed: 12/17/2022] Open
Abstract
Anticonvulsants can increase the risk of developing neurotoxicity in infants; however, the underlying mechanism has not been elucidated to date. Thyroxine [3,5,3',5'-l-tetraiodothyronine (T4)] plays crucial roles in the development of the central nervous system. In this study, we hypothesized that induction of UDP-glucuronosyltransferase 1A1 (UGT1A1)-an enzyme involved in the metabolism of T4-by anticonvulsants would reduce serum T4 levels and cause neurodevelopmental toxicity. Exposure of mice to phenytoin during both the prenatal and postnatal periods significantly induced UGT1A1 and decreased serum T4 levels on postnatal day 14. In the phenytoin-treated mice, the mRNA levels of synaptophysin and synapsin I in the hippocampus were lower than those in the control mice. The thickness of the external granule cell layer was greater in phenytoin-treated mice, indicating that induction of UGT1A1 during the perinatal period caused neurodevelopmental disorders. Exposure to phenytoin during only the postnatal period also caused these neurodevelopmental disorders. A T4 replacement attenuated the increase in thickness of the external granule cell layer, indicating that the reduced T4 was specifically associated with the phenytoin-induced neurodevelopmental disorder. In addition, these neurodevelopmental disorders were also found in the carbamazepine- and pregnenolone-16-α-carbonitrile-treated mice. Our study is the first to indicate that UGT1A1 can control neurodevelopment by regulating serum T4 levels.
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Affiliation(s)
- Rika Hirashima
- Department of Pharmaceutics (R.H., A.S., T.I., R.F.), Division of Biostatistics (H.M.), and Department of Pharmacognosy (H.T., Y.K.), School of Pharmacy, Kitasato University, Tokyo, Japan; and Laboratory of Environmental Toxicology, Department of Pharmacology, University of California San Diego, La Jolla, California (R.H.T.)
| | - Hirofumi Michimae
- Department of Pharmaceutics (R.H., A.S., T.I., R.F.), Division of Biostatistics (H.M.), and Department of Pharmacognosy (H.T., Y.K.), School of Pharmacy, Kitasato University, Tokyo, Japan; and Laboratory of Environmental Toxicology, Department of Pharmacology, University of California San Diego, La Jolla, California (R.H.T.)
| | - Hiroaki Takemoto
- Department of Pharmaceutics (R.H., A.S., T.I., R.F.), Division of Biostatistics (H.M.), and Department of Pharmacognosy (H.T., Y.K.), School of Pharmacy, Kitasato University, Tokyo, Japan; and Laboratory of Environmental Toxicology, Department of Pharmacology, University of California San Diego, La Jolla, California (R.H.T.)
| | - Aya Sasaki
- Department of Pharmaceutics (R.H., A.S., T.I., R.F.), Division of Biostatistics (H.M.), and Department of Pharmacognosy (H.T., Y.K.), School of Pharmacy, Kitasato University, Tokyo, Japan; and Laboratory of Environmental Toxicology, Department of Pharmacology, University of California San Diego, La Jolla, California (R.H.T.)
| | - Yoshinori Kobayashi
- Department of Pharmaceutics (R.H., A.S., T.I., R.F.), Division of Biostatistics (H.M.), and Department of Pharmacognosy (H.T., Y.K.), School of Pharmacy, Kitasato University, Tokyo, Japan; and Laboratory of Environmental Toxicology, Department of Pharmacology, University of California San Diego, La Jolla, California (R.H.T.)
| | - Tomoo Itoh
- Department of Pharmaceutics (R.H., A.S., T.I., R.F.), Division of Biostatistics (H.M.), and Department of Pharmacognosy (H.T., Y.K.), School of Pharmacy, Kitasato University, Tokyo, Japan; and Laboratory of Environmental Toxicology, Department of Pharmacology, University of California San Diego, La Jolla, California (R.H.T.)
| | - Robert H Tukey
- Department of Pharmaceutics (R.H., A.S., T.I., R.F.), Division of Biostatistics (H.M.), and Department of Pharmacognosy (H.T., Y.K.), School of Pharmacy, Kitasato University, Tokyo, Japan; and Laboratory of Environmental Toxicology, Department of Pharmacology, University of California San Diego, La Jolla, California (R.H.T.)
| | - Ryoichi Fujiwara
- Department of Pharmaceutics (R.H., A.S., T.I., R.F.), Division of Biostatistics (H.M.), and Department of Pharmacognosy (H.T., Y.K.), School of Pharmacy, Kitasato University, Tokyo, Japan; and Laboratory of Environmental Toxicology, Department of Pharmacology, University of California San Diego, La Jolla, California (R.H.T.)
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22
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Bock KW. Roles of human UDP-glucuronosyltransferases in clearance and homeostasis of endogenous substrates, and functional implications. Biochem Pharmacol 2015; 96:77-82. [PMID: 25937523 DOI: 10.1016/j.bcp.2015.04.020] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 04/24/2015] [Indexed: 11/19/2022]
Abstract
Human UDP-glucuronosyltransferases (UGTs) are major phase II enzymes in the drug metabolism system. Despite major advances in characterization of UGT gene family members, their role in clearance and homeostasis of endogenous substrates is insufficiently understood. Endobiotic substrates including bilirubin, serotonin, eicosanoids, steroid hormones, bile acids, thyroxine and fat-soluble vitamins A and D are discussed. Species- and tissue/cell-dependent regulation of UGT expression by ligand-activated transcription factors is often involved in endobiotic homeostasis. However, roles of particular UGTs are often difficult to delineate since they function together with other enzymes and transporters. Better knowledge of endobiotic UGT substrates and consequences of their conjugation may help to understand evolutionary conserved UGT functions.
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Affiliation(s)
- Karl Walter Bock
- Department of Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology. University of Tübingen, Wilhelmstrasse 56, D-72074 Tübingen, Germany.
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23
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Chen X, Casas ME, Nielsen JL, Wimmer R, Bester K. Identification of Triclosan-O-Sulfate and other transformation products of Triclosan formed by activated sludge. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 505:39-46. [PMID: 25306094 DOI: 10.1016/j.scitotenv.2014.09.077] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 09/23/2014] [Accepted: 09/23/2014] [Indexed: 06/04/2023]
Abstract
Aerobic degradation experiments of Triclosan were performed in activated sludge to identify possible transformation products for this compound. During 7 days, the formation of biotransformation products such as 2,4-Dichlorophenol, 4-Chlorocatechol, 5-Hydroxy-Triclosan and other Monohydroxy-Triclosan derivatives as well as Dihydroxy-Triclosan-derivatives were observed. The structure of 5-Hydroxy-Triclosan was elucidated by NMR data for the first time in sludge degradation experiments. Additionally the production of a hitherto unknown transformation product in sludge, i.e., Triclosan-O-Sulfate was detected. During the incubations, the concentrations of this transformation product changed from zero to 330 μg L(-1). Based on the analysis of the biodegradation products, three types of reactions were identified: 1) chemical scission of ether bond to form phenols and catechols, 2) addition of OH moieties to the aromatic ring, and 3) adding of methyl or sulfate groups to the original hydroxyl group.
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Affiliation(s)
- Xijuan Chen
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Wenhua Road 72, 110016 Shenyang, China; Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Sohngaardsholmsvej 49, 9000 Aalborg, Denmark; Department of Environmental Science, Aarhus University, Frederiksborgsvej 399, 4000 Roskilde, Denmark
| | - Mònica Escolà Casas
- Department of Environmental Science, Aarhus University, Frederiksborgsvej 399, 4000 Roskilde, Denmark
| | - Jeppe Lund Nielsen
- Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Sohngaardsholmsvej 49, 9000 Aalborg, Denmark
| | - Reinhard Wimmer
- Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Sohngaardsholmsvej 49, 9000 Aalborg, Denmark
| | - Kai Bester
- Department of Environmental Science, Aarhus University, Frederiksborgsvej 399, 4000 Roskilde, Denmark.
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24
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Gouliarmou V, Pelkonen O, Coecke S. Differentiation-Promoting Medium Additives for Hepatocyte Cultivation and Cryopreservation. Methods Mol Biol 2015; 1250:143-159. [PMID: 26272140 DOI: 10.1007/978-1-4939-2074-7_10] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Isolated primary hepatocytes are considered as the reference system for in vitro hepatic methods. Following the isolation of primary hepatocytes from liver tissue, an unfavorable process named dedifferentiation is initiated leading to the attenuation of the hepatocellular phenotype both at the morphological and functional level. Freshly isolated hepatocytes can be used immediately or can be cryopreserved for future purposes. Currently, a number of antidedifferentiation strategies exist to extend the life span of isolated hepatocytes. The addition of differentiation-promoting compounds to the hepatocyte culture medium is the oldest and simplest antidedifferentiation approach applied. In the present chapter, the most commonly used medium additives for cultivation and cryopreservation of primary hepatocytes are reviewed.
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Affiliation(s)
- Varvara Gouliarmou
- EURL ECVAM, Systems Toxicology Unit, Institute for Health and Consumer Protection, European Commission, Joint Research Center, Via Fermi 2749, Ispra, 21027, Italy
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