1
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Ryu S, Yamaguchi E, Sadegh Modaresi SM, Agudelo J, Costales C, West MA, Fischer F, Slitt AL. Evaluation of 14 PFAS for permeability and organic anion transporter interactions: Implications for renal clearance in humans. CHEMOSPHERE 2024; 361:142390. [PMID: 38801906 DOI: 10.1016/j.chemosphere.2024.142390] [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: 02/17/2024] [Revised: 04/26/2024] [Accepted: 05/19/2024] [Indexed: 05/29/2024]
Abstract
Per- and polyfluoroalkyl substances (PFAS) encompass a diverse group of synthetic fluorinated chemicals known to elicit adverse health effects in animals and humans. However, only a few studies investigated the mechanisms underlying clearance of PFAS. Herein, the relevance of human renal transporters and permeability to clearance and bioaccumulation for 14 PFAS containing three to eleven perfluorinated carbon atoms (ηpfc = 3-11) and several functional head-groups was investigated. Apparent permeabilities and interactions with human transporters were measured using in vitro cell-based assays, including the MDCK-LE cell line, and HEK293 stable transfected cell lines expressing organic anion transporter (OAT) 1-4 and organic cation transporter (OCT) 2. The results generated align with the Extended Clearance Classification System (ECCS), affirming that permeability, molecular weight, and ionization serve as robust predictors of clearance and renal transporter engagement. Notably, PFAS with low permeability (ECCS 3A and 3B) exhibited substantial substrate activity for OAT1 and OAT3, indicative of active renal secretion. Furthermore, we highlight the potential contribution of OAT4-mediated reabsorption to the renal clearance of PFAS with short ηpfc, such as perfluorohexane sulfonate (PFHxS). Our data advance our mechanistic understanding of renal clearance of PFAS in humans, provide useful input parameters for toxicokinetic models, and have broad implications for toxicological evaluation and regulatory considerations.
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Affiliation(s)
- Sangwoo Ryu
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, 02881, United States; Pharmacokinetics, Dynamics and Metabolism, Pfizer Worldwide Research & Development, Pfizer Inc., Groton, CT, 06340, United States
| | - Emi Yamaguchi
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Worldwide Research & Development, Pfizer Inc., Groton, CT, 06340, United States
| | - Seyed Mohamad Sadegh Modaresi
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, 02881, United States
| | - Juliana Agudelo
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, 02881, United States
| | - Chester Costales
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Worldwide Research & Development, Pfizer Inc., Groton, CT, 06340, United States
| | - Mark A West
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Worldwide Research & Development, Pfizer Inc., Groton, CT, 06340, United States
| | - Fabian Fischer
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, 02881, United States; Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, United States.
| | - Angela L Slitt
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, 02881, United States.
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2
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Nicol B, Vandenbossche-Goddard E, Thorpe C, Newman R, Patel H, Yates D. A workflow to practically apply true dose considerations to in vitro testing for next generation risk assessment. Toxicology 2024; 505:153826. [PMID: 38719068 DOI: 10.1016/j.tox.2024.153826] [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: 03/05/2024] [Revised: 04/22/2024] [Accepted: 05/01/2024] [Indexed: 05/14/2024]
Abstract
With the move away from safety testing assessment based on data generated in experimental animals the concept of Next Generation Risk Assessment (NGRA) has arisen which instead uses data from in silico and in vitro models. A key uncertainty in risk assessment is the actual dose of test chemical at the target site, and therefore surrogate dose metrics, such as nominal concentration in test media are used to describe in vitro effect (or no-effect) doses. The reliability and accuracy of the risk assessment therefore depends largely on our ability to understand and characterise the relationship between the dose metrics used and the actual biologically effective dose at the target site. The objective of this publication is to use 40 case study chemicals to illustrate how in vitro dose considerations can be applied to characterise the "true dose" and build confidence in the understanding of the biologically effective dose in in vitro test systems for the determination e.g. points of departure (PoDs) for NGRA. We propose a workflow that can be applied to assess whether the nominal test concentration can be considered a conservative dose metric for use in NGRA. The workflow examines the implications of volatility, stability, hydrophobicity, binding to plastic and serum, solubility, and the potential use of in silico models for some of these parameters. For the majority of the case study chemicals we found that the use of nominal concentrations in risk assessment would result in conservative decision making. However, for serval chemicals a potential for underestimation of the risk in humans in vivo based on in vitro nominal effect concentrations was identified, and approaches for refinement by characterisation of the actual effect concentration are proposed.
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Affiliation(s)
- Beate Nicol
- Unilever Safety and Environmental Assurance Centre, Colworth Science Park, Sharnbrook, Bedford, Bedfordshire MK44 1LQ, UK
| | - Evita Vandenbossche-Goddard
- Unilever Safety and Environmental Assurance Centre, Colworth Science Park, Sharnbrook, Bedford, Bedfordshire MK44 1LQ, UK.
| | - Charlotte Thorpe
- Unilever Safety and Environmental Assurance Centre, Colworth Science Park, Sharnbrook, Bedford, Bedfordshire MK44 1LQ, UK
| | | | - Hiral Patel
- Charles River Laboratories, Cambridgeshire CB10 1XL, UK
| | - Dawn Yates
- Charles River Laboratories, Cambridgeshire CB10 1XL, UK
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3
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Huchthausen J, Braasch J, Escher BI, König M, Henneberger L. Effects of Chemicals in Reporter Gene Bioassays with Different Metabolic Activities Compared to Baseline Toxicity. Chem Res Toxicol 2024; 37:744-756. [PMID: 38652132 PMCID: PMC11110108 DOI: 10.1021/acs.chemrestox.4c00017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 04/05/2024] [Accepted: 04/09/2024] [Indexed: 04/25/2024]
Abstract
High-throughput cell-based bioassays are used for chemical screening and risk assessment. Chemical transformation processes caused by abiotic degradation or metabolization can reduce the chemical concentration or, in some cases, lead to the formation of more toxic transformation products. Unaccounted loss processes may falsify the bioassay results. Capturing the formation and effects of transformation products is important for relating the in vitro effects to in vivo. Reporter gene cell lines are believed to have low metabolic activity, but inducibility of cytochrome P450 (CYP) enzymes has been reported. Baseline toxicity is the minimal toxicity a chemical can have and is caused by the incorporation of the chemical into cell membranes. In the present study, we improved an existing baseline toxicity model based on a newly defined critical membrane burden derived from freely dissolved effect concentrations, which are directly related to the membrane concentration. Experimental effect concentrations of 94 chemicals in three bioassays (AREc32, ARE-bla and GR-bla) were compared with baseline toxicity by calculating the toxic ratio (TR). CYP activities of all cell lines were determined by using fluorescence-based assays. Only ARE-bla showed a low basal CYP activity and inducibility and AREc32 showed a low inducibility. Overall cytotoxicity was similar in all three assays despite the different metabolic activities indicating that chemical metabolism is not relevant for the cytotoxicity of the tested chemicals in these assays. Up to 28 chemicals showed specific cytotoxicity with TR > 10 in the bioassays, but baseline toxicity could explain the effects of the majority of the remaining chemicals. Seven chemicals showed TR < 0.1 indicating inaccurate physicochemical properties or experimental artifacts like chemical precipitation, volatilization, degradation, or other loss processes during the in vitro bioassay. The new baseline model can be used not only to identify specific cytotoxicity mechanisms but also to identify potential problems in the experimental performance or evaluation of the bioassay and thus improve the quality of the bioassay data.
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Affiliation(s)
- Julia Huchthausen
- Department
of Cell Toxicology, Helmholtz Centre for
Environmental Research − UFZ, Permoserstr. 15, 04318 Leipzig, Germany
| | - Jenny Braasch
- Department
of Cell Toxicology, Helmholtz Centre for
Environmental Research − UFZ, Permoserstr. 15, 04318 Leipzig, Germany
| | - Beate I. Escher
- Department
of Cell Toxicology, Helmholtz Centre for
Environmental Research − UFZ, Permoserstr. 15, 04318 Leipzig, Germany
- Environmental
Toxicology, Department of Geosciences, Eberhard
Karls University Tübingen, 72076 Tübingen, Germany
| | - Maria König
- Department
of Cell Toxicology, Helmholtz Centre for
Environmental Research − UFZ, Permoserstr. 15, 04318 Leipzig, Germany
| | - Luise Henneberger
- Department
of Cell Toxicology, Helmholtz Centre for
Environmental Research − UFZ, Permoserstr. 15, 04318 Leipzig, Germany
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4
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Kemas AM, Zandi Shafagh R, Taebnia N, Michel M, Preiss L, Hofmann U, Lauschke VM. Compound Absorption in Polymer Devices Impairs the Translatability of Preclinical Safety Assessments. Adv Healthc Mater 2024; 13:e2303561. [PMID: 38053301 DOI: 10.1002/adhm.202303561] [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: 11/07/2023] [Indexed: 12/07/2023]
Abstract
Organotypic and microphysiological systems (MPS) that can emulate the molecular phenotype and function of human tissues, such as liver, are increasingly used in preclinical drug development. However, despite their improved predictivity, drug development success rates have remained low with most compounds failing in clinical phases despite promising preclinical data. Here, it is tested whether absorption of small molecules to polymers commonly used for MPS fabrication can impact preclinical pharmacological and toxicological assessments and contribute to the high clinical failure rates. To this end, identical devices are fabricated from eight different MPS polymers and absorption of prototypic compounds with different physicochemical properties are analyzed. It is found that overall absorption is primarily driven by compound hydrophobicity and the number of rotatable bonds. However, absorption can differ by >1000-fold between polymers with polydimethyl siloxane (PDMS) being most absorptive, whereas polytetrafluoroethylene (PTFE) and thiol-ene epoxy (TEE) absorbed the least. Strikingly, organotypic primary human liver cultures successfully flagged hydrophobic hepatotoxins in lowly absorbing TEE devices at therapeutically relevant concentrations, whereas isogenic cultures in PDMS devices are resistant, resulting in false negative safety signals. Combined, these results can guide the selection of MPS materials and facilitate the development of preclinical assays with improved translatability.
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Affiliation(s)
- Aurino M Kemas
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, 17177, Sweden
| | - Reza Zandi Shafagh
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, 17177, Sweden
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, 70376, Stuttgart, Germany
- University of Tuebingen, 72074, Tuebingen, Germany
- Division of Micro- and Nanosystems, KTH Royal Institute of Technology, Stockholm, 10044, Sweden
| | - Nayere Taebnia
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, 17177, Sweden
| | - Maurice Michel
- Department of Oncology and Pathology, Science for Life Laboratory, Karolinska Institutet, Stockholm, 17165, Sweden
| | - Lena Preiss
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, 17177, Sweden
- Department of Drug Metabolism and Pharmacokinetics (DMPK), Merck KGaA, 64293, Darmstadt, Germany
| | - Ute Hofmann
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, 70376, Stuttgart, Germany
| | - Volker M Lauschke
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, 17177, Sweden
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, 70376, Stuttgart, Germany
- University of Tuebingen, 72074, Tuebingen, Germany
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5
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Town RM, van Leeuwen HP, Duval JFL. Effect of Polymer Aging on Uptake/Release Kinetics of Metal Ions and Organic Molecules by Micro- and Nanoplastics: Implications for the Bioavailability of the Associated Compounds. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:16552-16563. [PMID: 37856883 PMCID: PMC10620988 DOI: 10.1021/acs.est.3c05148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 09/16/2023] [Accepted: 10/01/2023] [Indexed: 10/21/2023]
Abstract
The main driver of the potential toxicity of micro- and nanoplastics toward biota is often the release of compounds initially present in the plastic, i.e., polymer additives, as well as environmentally acquired metals and/or organic contaminants. Plastic particles degrade in the environment via various mechanisms and at different rates depending on the particle size/geometry, polymer type, and the prevailing physical and chemical conditions. The rate and extent of polymer degradation have obvious consequences for the uptake/release kinetics and, thus, the bioavailability of compounds associated with plastic particles. Herein, we develop a theoretical framework to describe the uptake and release kinetics of metal ions and organic compounds by plastic particles and apply it to the analysis of experimental data for pristine and aged micro- and nanoplastics. In particular, we elucidate the contribution of transient processes to the overall kinetics of plastic reactivity toward aquatic contaminants and demonstrate the paramount importance of intraparticulate contaminant diffusion.
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Affiliation(s)
- Raewyn M. Town
- ECOSPHERE,
Department of Biology, Universiteit Antwerpen, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
| | - Herman P. van Leeuwen
- ECOSPHERE,
Department of Biology, Universiteit Antwerpen, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
- Physical
Chemistry and Soft Matter, Wageningen University
& Research, Stippeneng
4, 6708 WE Wageningen, The Netherlands
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6
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Paranjape N, Dean LE, Martinez A, Tjalkens RB, Lehmler HJ, Doorn JA. Structure-Activity Relationship of Lower Chlorinated Biphenyls and Their Human-Relevant Metabolites for Astrocyte Toxicity. Chem Res Toxicol 2023; 36:971-981. [PMID: 37279407 PMCID: PMC10283044 DOI: 10.1021/acs.chemrestox.3c00095] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Indexed: 06/08/2023]
Abstract
Exposure to polychlorinated biphenyls (PCBs) is associated with developmental neurotoxicity and neurodegenerative disorders; however, the underlying mechanisms of pathogenesis are unknown. Existing literature has focused mainly on using neurons as a model system to study mechanisms of PCB-mediated neurotoxicity, overlooking the role of glial cells, such as astrocytes. As normal brain function is largely astrocyte-dependent, we hypothesize that astrocytes play an important role in PCB-mediated injury to neurons. We assessed the toxicity of two commercial PCB mixtures, Aroclor 1016 and Aroclor 1254, and a non-Aroclor PCB mixture found in residential air called the Cabinet mixture, all of which contain lower chlorinated PCBs (LC-PCBs) found in indoor and outdoor air. We further assessed the toxicity of five abundant airborne LC-PCBs and their corresponding human-relevant metabolites in vitro models of astrocytes, namely, the C6 cell line and primary astrocytes isolated from Sprague-Dawley rats and C57BL/6 mice. PCB52 and its human-relevant hydroxylated and sulfated metabolites were found to be the most toxic compounds. No significant sex-dependent cell viability differences were observed in rat primary astrocytes. Based on the equilibrium partitioning model, it was predicted that the partitioning of LC-PCBs and their corresponding metabolites in biotic and abiotic compartments of the cell culture system is structure-dependent and that the observed toxicity is consistent with this prediction. This study, for the first time, shows that astrocytes are sensitive targets of LC-PCBs and their human-relevant metabolites and that further research to identify mechanistic targets of PCB exposure in glial cells is necessary.
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Affiliation(s)
- Neha Paranjape
- Department
of Pharmaceutical Sciences & Experimental Therapeutics, College
of Pharmacy, University of Iowa, Iowa City, Iowa 52242, United States
- Department
of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa 52242, United States
| | - Laura E. Dean
- Department
of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa 52242, United States
| | - Andres Martinez
- Department
of Civil and Environmental Engineering, IIHR-Hydroscience & Engineering, University of Iowa, Iowa City, Iowa 52242, United States
| | - Ronald B. Tjalkens
- Department
of Environmental and Radiological Health Sciences, College of Veterinary
Medicine and Biomedical Sciences, Colorado
State University, Fort Collins, Colorado 80521, United States
| | - Hans-Joachim Lehmler
- Department
of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa 52242, United States
| | - Jonathan A. Doorn
- Department
of Pharmaceutical Sciences & Experimental Therapeutics, College
of Pharmacy, University of Iowa, Iowa City, Iowa 52242, United States
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7
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De Oro-Carretero P, Sanz-Landaluze J. Miniaturized method for the quantification of persistent organic pollutants and their metabolites in HepG2 cells: assessment of their biotransformation. Anal Bioanal Chem 2023:10.1007/s00216-023-04781-w. [PMID: 37289209 DOI: 10.1007/s00216-023-04781-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 05/22/2023] [Accepted: 05/30/2023] [Indexed: 06/09/2023]
Abstract
Biotransformation can greatly influence the accumulation and, subsequently, toxicity of substances in living beings. Although traditionally these studies to quantify metabolization of a compound have been carried out with in vivo species, currently, in vitro test methods with very different cell lines are being developed for their evaluation. However, this is still a very limited field due to multiple variables of a very diverse nature. So, an increasing number of analytical chemists are working with cells or other similar biological samples of very small size. This makes it necessary to address the development of analytical methods that allow determining their concentration both inside the cells and in their exposure medium. The aim of this study is to develop a set of analytical methodologies for the quantification of polycyclic aromatic hydrocarbons, PAHs (phenanthrene, PHE), and polybrominated diphenyl ethers, PBDEs (2,2',4,4'-tetrabromodiphenyl ether, BDE-47), and their major metabolites in cells and their exposure medium. Analytical methodologies, based on miniaturized ultrasound probe-assisted extraction, gas chromatography-mass spectrometry-microelectron capture detector (GC-MS-µECD), and liquid chromatography-fluorescence detector (LC-FL) determination techniques, have been optimized and then applied to a biotransformation study in HepG2 at 48 h of exposure. Significant concentrations of the major metabolites of PHE (1-OH, 2-OH, 3-OH, 4-OH-, and 9-OH-PHE) and BDE-47 (5-MeO-, 5-OH-, and 3-OH-BDE-47) were detected and quantified inside the cells and in the exposure medium. These results provide a new method for determination and improve information on the metabolization ratios for a better knowledge of the metabolic pathways and their toxicity.
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Affiliation(s)
- Paloma De Oro-Carretero
- Department of Analytical Chemistry, Faculty of Chemical Science, Complutense University of Madrid, Avenida Complutense S/N, 28040, Madrid, Spain.
| | - Jon Sanz-Landaluze
- Department of Analytical Chemistry, Faculty of Chemical Science, Complutense University of Madrid, Avenida Complutense S/N, 28040, Madrid, Spain
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8
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Qin W, Henneberger L, Huchthausen J, König M, Escher BI. Role of bioavailability and protein binding of four anionic perfluoroalkyl substances in cell-based bioassays for quantitative in vitro to in vivo extrapolations. ENVIRONMENT INTERNATIONAL 2023; 173:107857. [PMID: 36881956 DOI: 10.1016/j.envint.2023.107857] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 02/24/2023] [Accepted: 02/25/2023] [Indexed: 06/18/2023]
Abstract
Perfluoroalkyl substances (PFAS) are persistent and pose a risk to human health. High throughput screening (HTS) cell-based bioassays may inform risk assessment of PFAS provided that quantitative in vitro to in vivo extrapolation (QIVIVE) can be developed. The QIVIVE ratio is the ratio of nominal (Cnom) or freely dissolved concentration (Cfree) in human blood to Cnom or Cfree in the bioassays. Considering that the concentrations of PFAS in human plasma and in vitro bioassays may vary by orders of magnitude, we tested the hypothesis that anionic PFAS bind to proteins concentration-dependently and therefore the binding differs substantially between human plasma and bioassays, which has an impact on QIVIVE. Solid phase microextraction (SPME) with C18-coated fibers served to quantify the Cfree of four anionic PFAS (perfluorobutanoate (PFBA), perfluorooctanoate (PFOA), perfluorohexane sulfonate (PFHxS) and perfluorooctane sulfonate (PFOS)) in the presence of proteins and lipid, medium components, cells and human plasma over five orders of magnitude in concentrations. The C18-SPME method was used to quantify the non-linear binding to proteins, human plasma and medium, and the partition constants to cells. These binding parameters were used to predict Cfree of PFAS in cell bioassays and human plasma by a concentration-dependent mass balance model (MBM). The approach was illustrated with a reporter gene assay indicating activation of the peroxisome proliferator-activated receptor gamma (PPARγ-GeneBLAzer). Blood plasma levels were collected from literature for occupational exposure and the general population. The QIVIVEnom ratios were higher than the QIVIVEfree ratios due to the strong affinity to proteins and large differences in protein contents between human blood and bioassays. For human health risk assessment, the QIVIVEfree ratios of many in vitro assays need to be combined to cover all health relevant endpoints. If Cfree cannot be measured, they can be estimated with the MBM and concentration-dependent distribution ratios.
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Affiliation(s)
- Weiping Qin
- Department of Cell Toxicology, UFZ-Helmholtz Centre for Environmental Research, 04318 Leipzig, Germany; Environmental Toxicology, Department of Geosciences, Eberhard Karls University Tübingen, Schnarrenbergstr, 94-96, DE-72076 Tübingen, Germany
| | - Luise Henneberger
- Department of Cell Toxicology, UFZ-Helmholtz Centre for Environmental Research, 04318 Leipzig, Germany
| | - Julia Huchthausen
- Department of Cell Toxicology, UFZ-Helmholtz Centre for Environmental Research, 04318 Leipzig, Germany; Environmental Toxicology, Department of Geosciences, Eberhard Karls University Tübingen, Schnarrenbergstr, 94-96, DE-72076 Tübingen, Germany
| | - Maria König
- Department of Cell Toxicology, UFZ-Helmholtz Centre for Environmental Research, 04318 Leipzig, Germany
| | - Beate I Escher
- Department of Cell Toxicology, UFZ-Helmholtz Centre for Environmental Research, 04318 Leipzig, Germany; Environmental Toxicology, Department of Geosciences, Eberhard Karls University Tübingen, Schnarrenbergstr, 94-96, DE-72076 Tübingen, Germany.
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9
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Cordova AC, Ford LC, Valdiviezo A, Roman-Hubers AT, McDonald TJ, Chiu WA, Rusyn I. Dosing Methods to Enable Cell-Based In Vitro Testing of Complex Substances: A Case Study with a PAH Mixture. TOXICS 2022; 11:19. [PMID: 36668745 PMCID: PMC9866728 DOI: 10.3390/toxics11010019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 12/21/2022] [Accepted: 12/24/2022] [Indexed: 06/17/2023]
Abstract
Cell-based testing of multi-constituent substances and mixtures for their potential adverse health effects is difficult due to their complex composition and physical-chemical characteristics. Various extraction methods are typically used to enable studies in vitro; however, a limited number of solvents are biocompatible with in vitro studies and the extracts may not fully represent the original test article's composition. While the methods for dosing with "difficult-to-test" substances in aquatic toxicity studies are well defined and widely used, they are largely unsuited for small-volume (100 microliters or less) in vitro studies with mammalian cells. Therefore, we aimed to evaluate suitability of various scaled-down dosing methods for high-throughput in vitro testing by using a mixture of polycyclic aromatic hydrocarbons (PAH). Specifically, we compared passive dosing via silicone micro-O-rings, cell culture media-accommodated fraction, and traditional solvent (dimethyl sulfoxide) extraction procedures. Gas chromatography-tandem mass spectrometry (GC-MS/MS) was used to evaluate kinetics of PAH absorption to micro-O-rings, as well as recovery of PAH and the extent of protein binding in cell culture media with and without cells for each dosing method. Bioavailability of the mixture from different dosing methods was also evaluated by characterizing in vitro cytotoxicity of the PAH mixture using EA.hy926 and HepG2 human cell lines. Of the tested dosing methods, media accommodated fraction (MAF) was determined to be the most appropriate method for cell-based studies of PAH-containing complex substances and mixtures. This conclusion is based on the observation that the highest fraction of the starting materials can be delivered using media accommodated fraction approach into cell culture media and thus enable concentration-response in vitro testing.
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Affiliation(s)
- Alexandra C. Cordova
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Lucie C. Ford
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Alan Valdiviezo
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Alina T. Roman-Hubers
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Thomas J. McDonald
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
- Departments of Environmental and Occupational Health, Texas A&M University, College Station, TX 77843, USA
| | - Weihsueh A. Chiu
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Ivan Rusyn
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
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10
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DNA adducts as link between in vitro and in vivo carcinogenicity - A case study with benzo[ a]pyrene. Curr Res Toxicol 2022; 4:100097. [PMID: 36590448 PMCID: PMC9794893 DOI: 10.1016/j.crtox.2022.100097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 12/07/2022] [Accepted: 12/12/2022] [Indexed: 12/15/2022] Open
Abstract
To reduce the need for animal tests, in vitro assays are often used as alternative methods. To derive toxic doses for higher tier organisms from in vitro assay results, quantitative in vitro-in vivo extrapolation (qIVIVE) based on physiological-based toxicokinetic (PBTK) models is typically the preferred approach. Such PBTK models require many input parameters to address the route from dose to target site concentration. However, respective data is very often not available. Hence, our aim is to call attention to an alternative way to build a link between animal (in vivo) and cell-derived (in vitro) toxicity data. To this end, we selected the carcinogenic chemical benzo[a]pyrene (BaP) for our study. Our approach relates both in vitro assay and in vivo data to a main intermediate marker structure for carcinogenicity on the subcellular level - the BaP-DNA adduct BaP-7,8-dihydrodiol-9,10-epoxide-deoxyguanosine. Thus, BaP dose is directly linked to a measure of the toxicity-initiating event. We used Syrian hamster embryo (SHE) and Balb/c 3T3 cell transformation assay as in vitro data and compared these data to outcomes of in vivo carcinogenicity tests in rodents. In vitro and in vivo DNA adduct levels range within three orders of magnitude. Especially metabolic saturation at higher doses and interspecies variabilities are identified and critically discussed as possible sources of errors in our simplified approach. Finally, our study points out possible routes to overcome limitations of the envisaged approach in order to allow for a reliable qIVIVE in the future.
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11
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Lee J, Huchthausen J, Schlichting R, Scholz S, Henneberger L, Escher BI. Validation of an SH-SY5Y Cell-Based Acetylcholinesterase Inhibition Assay for Water Quality Assessment. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2022; 41:3046-3057. [PMID: 36165561 DOI: 10.1002/etc.5490] [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: 05/01/2022] [Revised: 06/23/2022] [Accepted: 09/23/2022] [Indexed: 06/16/2023]
Abstract
The acetylcholinesterase (AChE) inhibition assay has been frequently applied for environmental monitoring to capture insecticides such as organothiophosphates (OTPs) and carbamates. However, natural organic matter such as dissolved organic carbon (DOC) co-extracted with solid-phase extraction from environmental samples can produce false-negative AChE inhibition in free enzyme-based AChE assays. We evaluated whether disturbance by DOC can be alleviated in a cell-based AChE assay using differentiated human neuroblastoma SH-SY5Y cells. The exposure duration was set at an optimum of 3 h considering the effects of OTPs and carbamates. Because loss to the airspace was expected for the more volatile OTPs (chlorpyrifos, diazinon, and parathion), the chemical loss in this bioassay setup was investigated using solid-phase microextraction followed by chemical analysis. The three OTPs were relatively well retained (loss <34%) during 3 h of exposure in the 384-well plate, but higher losses occurred on prolonged exposure, accompanied by slight cross-contamination of adjacent wells. Inhibition of AChE by paraoxon-ethyl was not altered in the presence of up to 68 mgc /L Aldrich humic acid used as surrogate for DOC. Binary mixtures of paraoxon-ethyl and water extracts showed concentration-additive effects. These experiments confirmed that the matrix in water extracts does not disturb the assay, unlike purified enzyme-based AChE assays. The cell-based AChE assay proved to be suitable for testing water samples with effect concentrations causing 50% inhibition of AChE at relative enrichments of 0.5-10 in river water samples, which were distinctly lower than corresponding cytotoxicity, confirming the high sensitivity of the cell-based AChE inhibition assay and its relevance for water quality monitoring. Environ Toxicol Chem 2022;41:3046-3057. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
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Affiliation(s)
- Jungeun Lee
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Julia Huchthausen
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Rita Schlichting
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Stefan Scholz
- Department of Bioanalytical Ecotoxicology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Luise Henneberger
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Beate I Escher
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
- Department of Environmental Toxicology and Geosciences, Eberhard Karls University of Tübingen, Tübingen, Germany
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Dimitrijevic D, Fabian E, Nicol B, Funk-Weyer D, Landsiedel R. Toward Realistic Dosimetry In Vitro: Determining Effective Concentrations of Test Substances in Cell Culture and Their Prediction by an In Silico Mass Balance Model. Chem Res Toxicol 2022; 35:1962-1973. [PMID: 36264934 PMCID: PMC9682521 DOI: 10.1021/acs.chemrestox.2c00128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Nominal concentrations (CNom) in cell culture media are routinely used to define concentration-effect relationships in the in vitro toxicology. The actual concentration in the medium (CMedium) can be affected by adsorption processes, evaporation, or degradation of chemicals. Therefore, we measured the total and free concentration of 12 chemicals, covering a wide range of lipophilicity (log KOW -0.07-6.84), in the culture medium (CMedium) and cells (CCell) after incubation with Balb/c 3T3 cells for up to 48 h. Measured values were compared to predictions using an as yet unpublished in silico mass balance model that combined relevant equations from similar models published by others. The total CMedium for all chemicals except tamoxifen (TAM) were similar to the CNom. This was attributed to the cellular uptake of TAM and accumulation into lysosomes. The free (i.e., unbound) CMedium for the low/no protein binding chemicals were similar to the CNom, whereas values of all moderately to highly protein-bound chemicals were less than 30% of the CNom. Of the 12 chemicals, the two most hydrophilic chemicals, acetaminophen (APAP) and caffeine (CAF), were the only ones for which the CCell was the same as the CNom. The CCell for all other chemicals tended to increase over time and were all 2- to 274-fold higher than CNom. Measurements of CCytosol, using a digitonin method to release cytosol, compared well with CCell (using a freeze-thaw method) for four chemicals (CAF, APAP, FLU, and KET), indicating that both methods could be used. The mass balance model predicted the total CMedium within 30% of the measured values for 11 chemicals. The free CMedium of all 12 chemicals were predicted within 3-fold of the measured values. There was a poorer prediction of CCell values, with a median overprediction of 3- to 4-fold. In conclusion, while the number of chemicals in the study is limited, it demonstrates the large differences between CNom and total and free CMedium and CCell, which were also relatively well predicted by the mass balance model.
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Affiliation(s)
- Dunja Dimitrijevic
- Free
University of Berlin, Institute of Pharmacy, Pharmacology and Toxicology, Königin-Luise-Straße
2−4, 14195Berlin, Germany
| | - Eric Fabian
- BASF
SE, Experimental Toxicology and Ecology, Carl-Bosch-Straße 38, 67056Ludwigshafen am Rhein, Germany
| | - Beate Nicol
- Safety
& Environmental Assurance Centre, Unilever
U.K., Sharnbrook, MK44 ILQBedford, United Kingdom
| | - Dorothee Funk-Weyer
- BASF
SE, Experimental Toxicology and Ecology, Carl-Bosch-Straße 38, 67056Ludwigshafen am Rhein, Germany
| | - Robert Landsiedel
- Free
University of Berlin, Institute of Pharmacy, Pharmacology and Toxicology, Königin-Luise-Straße
2−4, 14195Berlin, Germany,BASF
SE, Experimental Toxicology and Ecology, Carl-Bosch-Straße 38, 67056Ludwigshafen am Rhein, Germany,. Fax: +49 621 60-58134
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Jang S, Ford LC, Rusyn I, Chiu WA. Cumulative Risk Meets Inter-Individual Variability: Probabilistic Concentration Addition of Complex Mixture Exposures in a Population-Based Human In Vitro Model. TOXICS 2022; 10:toxics10100549. [PMID: 36287830 PMCID: PMC9611413 DOI: 10.3390/toxics10100549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 09/03/2022] [Accepted: 09/16/2022] [Indexed: 05/16/2023]
Abstract
Although humans are continuously exposed to complex chemical mixtures in the environment, it has been extremely challenging to investigate the resulting cumulative risks and impacts. Recent studies proposed the use of “new approach methods,” in particular in vitro assays, for hazard and dose−response evaluation of mixtures. We previously found, using five human cell-based assays, that concentration addition (CA), the usual default approach to calculate cumulative risk, is mostly accurate to within an order of magnitude. Here, we extend these findings to further investigate how cell-based data can be used to quantify inter-individual variability in CA. Utilizing data from testing 42 Superfund priority chemicals separately and in 8 defined mixtures in a human cell-based population-wide in vitro model, we applied CA to predict effective concentrations for cytotoxicity for each individual, for “typical” (median) and “sensitive” (first percentile) members of the population, and for the median-to-sensitive individual ratio (defined as the toxicodynamic variability factor, TDVF). We quantified the accuracy of CA with the Loewe Additivity Index (LAI). We found that LAI varies more between different mixtures than between different individuals, and that predictions of the population median are generally more accurate than predictions for the “sensitive” individual or the TDVF. Moreover, LAI values were generally <1, indicating that the mixtures were more potent than predicted by CA. Together with our previous studies, we posit that new approach methods data from human cell-based in vitro assays, including multiple phenotypes in diverse cell types and studies in a population-wide model, can fill critical data gaps in cumulative risk assessment, but more sophisticated models of in vitro mixture additivity and bioavailability may be needed. In the meantime, because simple CA models may underestimate potency by an order of magnitude or more, either whole-mixture testing in vitro or, alternatively, more stringent benchmarks of cumulative risk indices (e.g., lower hazard index) may be needed to ensure public health protection.
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Affiliation(s)
- Suji Jang
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Lucie C. Ford
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Ivan Rusyn
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Weihsueh A. Chiu
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
- Correspondence: ; Tel.: +1-(979)-845-4106
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Sgouros AP, Revelas CJ, Lakkas AT, Theodorou DN. Solvation Free Energy of Dilute Grafted (Nano)Particles in Polymer Melts via the Self-Consistent Field Theory. J Phys Chem B 2022; 126:7454-7474. [DOI: 10.1021/acs.jpcb.2c05306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Aristotelis P. Sgouros
- School of Chemical Engineering, National Technical University of Athens (NTUA), GR-15780 Athens, Greece
| | - Constantinos J. Revelas
- School of Chemical Engineering, National Technical University of Athens (NTUA), GR-15780 Athens, Greece
| | - Apostolos T. Lakkas
- School of Chemical Engineering, National Technical University of Athens (NTUA), GR-15780 Athens, Greece
| | - Doros N. Theodorou
- School of Chemical Engineering, National Technical University of Athens (NTUA), GR-15780 Athens, Greece
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15
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Fischer FC, Hiki K, Endo S. Free Versus Bound Concentration: Passive Dosing from Polymer Meshes Elucidates Drivers of Toxicity in Aquatic Tests with Benthic Invertebrates. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2022. [PMID: 36039972 DOI: 10.1002/etc.5473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 07/25/2022] [Accepted: 08/23/2022] [Indexed: 06/15/2023]
Abstract
Aquatic toxicity tests with benthic organisms are used to predict the toxicity of hydrophobic organic chemicals (HOCs) in sediments, assuming that the freely dissolved concentration (Cfree ) is a good surrogate of bioavailability in the exposure system. However, Cfree of HOCs is difficult to control in water-only setups. Moreover, the role of dissolved organic carbon (DOC) in the occurrence of toxicity needs clarification because DOC concentrations in sediment porewater can be substantially higher than in typical test water. We introduced biocompatible polyethylene meshes with high sorptive capacities and fast release kinetics as a novel passive dosing phase, which maintained Cfree and Cwater (i.e., free + DOC-bound) in Hyalella azteca water-only tests. Adding the supernatant fraction of peat to test water as a DOC source increased Cwater to an extent comparable to sediment porewater and significantly increased and decreased the observed toxicity of permethrin and benzo[a]pyrene, respectively, to H. azteca. This result indicates that DOC can both benefit and harm test species likely due to the increased health after ingestion of DOC and to the uptake of DOC-bound HOCs, respectively. Passive dosing in combination with the addition of sediment DOC surrogates may better reflect exposure and habitat conditions in sediment porewater than conventional aquatic tests. Environ Toxicol Chem 2022;00:1-10. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
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Affiliation(s)
- Fabian C Fischer
- Health and Environmental Risk Division, National Institute for Environmental Studies, Onogawa, Tsukuba, Ibaraki, Japan
| | - Kyoshiro Hiki
- Health and Environmental Risk Division, National Institute for Environmental Studies, Onogawa, Tsukuba, Ibaraki, Japan
| | - Satoshi Endo
- Health and Environmental Risk Division, National Institute for Environmental Studies, Onogawa, Tsukuba, Ibaraki, Japan
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16
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Niu L, Henneberger L, Huchthausen J, Krauss M, Ogefere A, Escher BI. pH-Dependent Partitioning of Ionizable Organic Chemicals between the Silicone Polymer Polydimethylsiloxane (PDMS) and Water. ACS ENVIRONMENTAL AU 2022; 2:253-262. [PMID: 37102138 PMCID: PMC10114720 DOI: 10.1021/acsenvironau.1c00056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
The silicone polymer polydimethysiloxane (PDMS) is a popular passive sampler for in situ and ex situ sampling of hydrophobic organic chemicals. Despite its limited sorptive capacity for polar and ionizable organic chemicals (IOC), IOCs have been found in PDMS when extracting sediment and suspended particulate matter. The pH-dependent partitioning of 190 organics and IOCs covering a range of octanol-water partition constants log K ow from -0.3 to 7.7 was evaluated with a 10-day shaking method using mixtures composed of all chemicals at varying ratios of mass of PDMS to volume of water. This method reproduced the PDMS-water partition constant K PDMS/w of neutral chemicals from the literature and extended the dataset by 93 neutral chemicals. The existing quantitative structure-activity relationship between the log K ow and K PDMS/w could be extended with the measured K PDMS/w linearly to a log K ow of -0.3. Fully charged organics were not taken up into PDMS. Thirty-eight monoprotic organic acids and 42 bases showed negligible uptake of the charged species, and the pH dependence of the apparent D PDMS/w(pH) could be explained by the fraction of neutral species multiplied by the K PDMS/w of the neutral species of these IOCs. Seventeen multiprotic chemicals with up to three acidity constants pK a also showed a pH dependence of D PDMS/w(pH) with the tendency that the neutral and zwitterionic forms showed the highest D PDMS/w(pH). D PDMS/w(pH) of charged species of more hydrophobic multiprotic chemicals such as tetrabromobisphenol A and telmisartan was smaller but not negligible. Since these chemicals show high bioactivity, their contribution to mixture effects has to be considered when testing passive sampling extracts with in vitro bioassays. This work has further implications for understanding the role of microplastic as a vector for organic micropollutants.
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Affiliation(s)
- Lili Niu
- Department
of Cell Toxicology, UFZ − Helmholtz
Centre for Environmental Research, 04318 Leipzig, Germany
- Key
Laboratory of Pollution Exposure and Health Intervention of Zhejiang
Province, Interdisciplinary Research Academy (IRA), Zhejiang Shuren University, Hangzhou 310015, China
| | - Luise Henneberger
- Department
of Cell Toxicology, UFZ − Helmholtz
Centre for Environmental Research, 04318 Leipzig, Germany
| | - Julia Huchthausen
- Department
of Cell Toxicology, UFZ − Helmholtz
Centre for Environmental Research, 04318 Leipzig, Germany
| | - Martin Krauss
- Department
of Effect Directed Analysis, Helmholtz Centre
for Environmental Research, 04318 Leipzig, Germany
| | - Audrey Ogefere
- Department
of Cell Toxicology, UFZ − Helmholtz
Centre for Environmental Research, 04318 Leipzig, Germany
| | - Beate I. Escher
- Department
of Cell Toxicology, UFZ − Helmholtz
Centre for Environmental Research, 04318 Leipzig, Germany
- Center
for Applied Geoscience, Eberhard Karls University
of Tübingen, Schnarrenbergstr.
94-96, 72076 Tübingen, Germany
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17
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Screening of the Toxicity of Polystyrene Nano- and Microplastics Alone and in Combination with Benzo(a)pyrene in Brine Shrimp Larvae and Zebrafish Embryos. NANOMATERIALS 2022; 12:nano12060941. [PMID: 35335754 PMCID: PMC8948799 DOI: 10.3390/nano12060941] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/06/2022] [Accepted: 03/08/2022] [Indexed: 12/17/2022]
Abstract
The occurrence of nanoplastics (NPs) and microplastics (MPs) in aquatic ecosystems and their capacity to sorb hydrophobic pollutants is nowadays an issue of great concern. This study aimed to assess the potential bioavailability and acute toxicity of polystyrene (PS) NPs (50 and 500 nm) and of MPs (4.5 µm), alone and with sorbed benzo(a)pyrene (B(a)P), in the embryo/larval stages of brine shrimps and zebrafish. Exposure to pristine plastics up to 50.1 mg PS/L did not cause significant impact on brine shrimp survival, while some treatments of plastics-B(a)P and all concentrations of B(a)P (0.1–10 mg/L) resulted acutely toxic. In zebrafish, only the highest concentrations of MPs-B(a)P and B(a)P caused a significant increase of malformation prevalence. Ingestion of NPs was observed by 24–48 h of exposure in the two organisms (from 0.069 to 6.87 mg PS/L). In brine shrimps, NPs were observed over the body surface and within the digestive tract, associated with feces. In zebrafish, NPs were localized in the eyes, yolk sac, and tail at 72 h, showing their capacity to translocate and spread into the embryo. MP ingestion was only demonstrated for brine shrimps. In zebrafish embryos exposed to plastics-B(a)P, B(a)P appeared in the yolk sac of the embryos. The presence of B(a)P was also noticeable in brine shrimps exposed to 500 nm NPs-B(a)P. In conclusion, NPs entered and spread into the zebrafish embryo and PS NPs, and MPs were successful vectors of B(a)P to brine shrimp and zebrafish embryos. Particle size played a significant role in explaining the toxicity of plastics–B(a)P. Our study provides support for the idea that plastics may pose a risk to aquatic organisms when combined with persistent organic pollutants such as B(a)P.
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19
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Armitage JM, Sangion A, Parmar R, Looky AB, Arnot JA. Update and Evaluation of a High-Throughput In Vitro Mass Balance Distribution Model: IV-MBM EQP v2.0. TOXICS 2021; 9:toxics9110315. [PMID: 34822706 PMCID: PMC8625852 DOI: 10.3390/toxics9110315] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 11/15/2021] [Accepted: 11/17/2021] [Indexed: 11/16/2022]
Abstract
This study demonstrates the utility of an updated mass balance model for predicting the distribution of organic chemicals in in vitro test systems (IV-MBM EQP v2.0) and evaluates its performance with empirical data. The IV-MBM EQP v2.0 tool was parameterized and applied to four independent data sets with measured ratios of bulk medium or freely-dissolved to initial nominal concentrations (e.g., C24/C0 where C24 is the measured concentration after 24 h of exposure and C0 is the initial nominal concentration). Model performance varied depending on the data set, chemical properties (e.g., "volatiles" vs. "non-volatiles", neutral vs. ionizable organics), and model assumptions but overall is deemed acceptable. For example, the r2 was greater than 0.8 and the mean absolute error (MAE) in the predictions was less than a factor of two for most neutral organics included. Model performance was not as good for the ionizable organic chemicals included but the r2 was still greater than 0.7 and the MAE less than a factor of three. The IV-MBM EQP v2.0 model was subsequently applied to several hundred chemicals on Canada's Domestic Substances List (DSL) with nominal effects data (AC50s) reported for two in vitro assays. We report the frequency of chemicals with AC50s corresponding to predicted cell membrane concentrations in the baseline toxicity range (i.e., >20-60 mM) and tabulate the number of chemicals with "volatility issues" (majority of chemical in headspace) and "solubility issues" (freely-dissolved concentration greater than water solubility after distribution). In addition, the predicted "equivalent EQP blood concentrations" (i.e., blood concentration at equilibrium with predicted cellular concentration) were compared to the AC50s as a function of hydrophobicity (log octanol-water partition or distribution ratio). The predicted equivalent EQP blood concentrations exceed the AC50 by up to a factor of 100 depending on hydrophobicity and assay conditions. The implications of using AC50s as direct surrogates for human blood concentrations when estimating the oral equivalent doses using a toxicokinetic model (i.e., reverse dosimetry) are then briefly discussed.
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Affiliation(s)
- James M. Armitage
- AES Armitage Environmental Sciences, Inc., Ottawa, ON K1L 8C3, Canada
- Correspondence:
| | - Alessandro Sangion
- ARC Arnot Research and Consulting, Inc., Toronto, ON M4M 1W4, Canada; (A.S.); (R.P.); (A.B.L.); (J.A.A.)
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada
| | - Rohan Parmar
- ARC Arnot Research and Consulting, Inc., Toronto, ON M4M 1W4, Canada; (A.S.); (R.P.); (A.B.L.); (J.A.A.)
| | - Alexandra B. Looky
- ARC Arnot Research and Consulting, Inc., Toronto, ON M4M 1W4, Canada; (A.S.); (R.P.); (A.B.L.); (J.A.A.)
| | - Jon A. Arnot
- ARC Arnot Research and Consulting, Inc., Toronto, ON M4M 1W4, Canada; (A.S.); (R.P.); (A.B.L.); (J.A.A.)
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON M5S 1A8, Canada
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Fischer FC, Hiki K, Soetaert K, Endo S. Mind the Exposure Gaps-Modeling Chemical Transport in Sediment Toxicity Tests. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:11885-11893. [PMID: 34488347 DOI: 10.1021/acs.est.1c03201] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Chemical exposure in flow-through sediment toxicity tests can vary in time, between pore and overlying water, and amid free and bound states, complicating the link between toxicity and observable concentrations such as free pore (Cfree,pore), free overlying (Cfree,over), or the corresponding dissolved concentrations (Cdiss, free + bound to dissolved organic carbon, DOC). We introduce a numerical model that describes the desorption from sediments to pore water, diffusion through pores and the sediment-water boundary, DOC-mediated transport, and mixing in and outflow from overlying water. The model explained both the experimentally measured gap between Cfree,over and Cfree,pore and the continuous decrease in overlying Cdiss. Spatially resolved modeling suggested a steep concentration gradient present in the upper millimeter of the sediment due to slow chemical diffusion in sediment pores and fast outflux from the overlying water. In contrast to continuous decrease in overlying Cdiss expected for any chemical, Cfree,over of highly hydrophobic chemicals was kept relatively constant following desorption from DOC, a mechanism comparable to passive dosing. Our mechanistic analyses emphasize that exposure will depend on the chemical's hydrophobicity, the test organism habitat and uptake of bound chemicals, and the properties of sediment components, including DOC. The model can help to re-evaluate existing toxicity data, optimize experimental setups, and extrapolate laboratory toxicity data to field exposure.
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Affiliation(s)
- Fabian Christoph Fischer
- Health and Environmental Risk Division, National Institute for Environmental Studies (NIES), Onogawa 16-2, 305-8506 Tsukuba, Ibaraki, Japan
| | - Kyoshiro Hiki
- Health and Environmental Risk Division, National Institute for Environmental Studies (NIES), Onogawa 16-2, 305-8506 Tsukuba, Ibaraki, Japan
| | - Karline Soetaert
- Department of Estuarine and Delta Systems, NIOZ Royal Netherlands Institute for Sea Research, Korringaweg 7, 4401 NT Yerseke, The Netherlands
| | - Satoshi Endo
- Health and Environmental Risk Division, National Institute for Environmental Studies (NIES), Onogawa 16-2, 305-8506 Tsukuba, Ibaraki, Japan
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Lee J, Braun G, Henneberger L, König M, Schlichting R, Scholz S, Escher BI. Critical Membrane Concentration and Mass-Balance Model to Identify Baseline Cytotoxicity of Hydrophobic and Ionizable Organic Chemicals in Mammalian Cell Lines. Chem Res Toxicol 2021; 34:2100-2109. [PMID: 34357765 DOI: 10.1021/acs.chemrestox.1c00182] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
All chemicals can interfere with cellular membranes and this leads to baseline toxicity, which is the minimal toxicity any chemical elicits. The critical membrane burden is constant for all chemicals; that is, the dosing concentrations to trigger baseline toxicity decrease with increasing hydrophobicity of the chemicals. Quantitative structure-activity relationships, based on hydrophobicity of chemicals, have been established to predict nominal concentrations causing baseline toxicity in human and mammalian cell lines. However, their applicability is limited to hydrophilic neutral compounds. To develop a prediction model that includes more hydrophobic and charged organic chemicals, a mass balance model was applied for mammalian cells (AREc32, AhR-CALUX, PPARγ-BLA, and SH-SY5Y) considering different bioassay conditions. The critical membrane burden for baseline toxicity was converted into nominal concentration causing 10% cytotoxicity by baseline toxicity (IC10,baseline) using a mass balance model whose main chemical input parameter was the liposome-water partition constants (Klip/w) for neutral chemicals or the speciation-corrected Dlip/w(pH 7.4) for ionizable chemicals plus the bioassay-specific protein, lipid, and water contents of cells and media. In these bioassay-specific models, log(1/IC10,baseline) increased with increasing hydrophobicity, and the relationship started to level off at log Dlip/w around 2. The bioassay-specific models were applied to 392 chemicals covering a broad range of hydrophobicity and speciation. Comparing the predicted IC10,baseline and experimental cytotoxicity IC10, known baseline toxicants and many additional chemicals were identified as baseline toxicants, while the others were classified based on specificity of their modes of action in the four cell lines, confirming excess toxicity of some fungicides, antibiotics, and uncouplers. Given the similarity of the bioassay-specific models, we propose a generalized baseline-model for adherent human cell lines: log[1/IC10,baseline (M)] = 1.23 + 4.97 × (1 - e-0.236 log Dlip/w). The derived models for baseline toxicity may serve for specificity analysis in reporter gene and neurotoxicity assays as well as for planning the dosing for cell-based assays.
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Affiliation(s)
- Jungeun Lee
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, DE-04318 Leipzig, Germany
| | - Georg Braun
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, DE-04318 Leipzig, Germany
| | - Luise Henneberger
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, DE-04318 Leipzig, Germany
| | - Maria König
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, DE-04318 Leipzig, Germany
| | - Rita Schlichting
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, DE-04318 Leipzig, Germany
| | - Stefan Scholz
- Department of Bioanalytical Toxicology, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, DE-04318 Leipzig, Germany
| | - Beate I Escher
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, DE-04318 Leipzig, Germany.,Environmental Toxicology, Center for Applied Geoscience, Eberhard Karls University Tübingen, Scharrenbergstrasse 94-96, DE-72076 Tübingen, Germany
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22
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Smith KEC, Jeong Y. Passive Sampling and Dosing of Aquatic Organic Contaminant Mixtures for Ecotoxicological Analyses. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:9538-9547. [PMID: 33749267 DOI: 10.1021/acs.est.0c08067] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Toxicity results from exposure to mixtures of organic contaminants. Assessing this using ecotoxicity bioassays involves sampling of the environmental mixture and then introducing this into the test. The first step is accounting for the bioavailable levels of all mixture constituents. Passive sampling specifically targets these bioavailable fractions but the sampler-accumulated mixture varies with the compound and sampler properties as well as time. The second step involves reproducing and maintaining the sampled mixture constituents in the bioassay. Passive sampler extraction and spiking always leads to a skewed mixture profile in the test. Alternatively, the recovered passive samplers might be directly used in passive dosing mode. Here, the reproduced contaminant mixture depends on whether kinetic or equilibrium sampling applies. These concepts were tested for determining the combined toxicity of laboratory and field mixtures of aquatic contaminants in the Microtox and ER-Calux bioassays. Aqueous sample extraction and spiking, passive sampler extraction and spiking, and passive sampling and dosing were compared for first sampling and then introducing mixtures in toxicity bioassays. The analytical and toxicity results show that the correct way to first sample the bioavailable mixture profile, and then to reproduce and maintain this in the toxicity test, is by combining equilibrium passive sampling and dosing.
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Affiliation(s)
- Kilian E C Smith
- Environmental Safety Group, KIST Europe, Korea Institute of Science and Technology, Campus E 7.1, Saarbrücken, Germany
| | - Yoonah Jeong
- Environmental Safety Group, KIST Europe, Korea Institute of Science and Technology, Campus E 7.1, Saarbrücken, Germany
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23
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Effective exposure of chemicals in in vitro cell systems: A review of chemical distribution models. Toxicol In Vitro 2021; 73:105133. [DOI: 10.1016/j.tiv.2021.105133] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 02/11/2021] [Accepted: 02/25/2021] [Indexed: 12/23/2022]
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24
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Predicting exposure concentrations of chemicals with a wide range of volatility and hydrophobicity in different multi-well plate set-ups. Sci Rep 2021; 11:4680. [PMID: 33633258 PMCID: PMC7907087 DOI: 10.1038/s41598-021-84109-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 02/03/2021] [Indexed: 11/16/2022] Open
Abstract
Quantification of chemical toxicity in small-scale bioassays is challenging owing to small volumes used and extensive analytical resource needs. Yet, relying on nominal concentrations for effect determination maybe erroneous because loss processes can significantly reduce the actual exposure. Mechanistic models for predicting exposure concentrations based on distribution coefficients exist but require further validation with experimental data. Here we developed a complementary empirical model framework to predict chemical medium concentrations using different well-plate formats (24/48-well), plate covers (plastic lid, or additionally aluminum foil or adhesive foil), exposure volumes, and biological entities (fish, algal cells), focusing on the chemicals’ volatility and hydrophobicity as determinants. The type of plate cover and medium volume were identified as important drivers of volatile chemical loss, which could accurately be predicted by the framework. The model focusing on adhesive foil as cover was exemplary cross-validated and extrapolated to other set-ups, specifically 6-well plates with fish cells and 24-well plates with zebrafish embryos. Two case study model applications further demonstrated the utility of the empirical model framework for toxicity predictions. Thus, our approach can significantly improve the applicability of small-scale systems by providing accurate chemical concentrations in exposure media without resource- and time-intensive analytical measurements.
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25
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Evaluation of an in vitro assay to screen for the immunotoxic potential of chemicals to fish. Sci Rep 2021; 11:3167. [PMID: 33542403 PMCID: PMC7862612 DOI: 10.1038/s41598-021-82711-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 01/22/2021] [Indexed: 02/06/2023] Open
Abstract
A wide variety of environmental contaminants has been shown to disrupt immune functions of fish and may compromise their defense capability against pathogens. Immunotoxic effects, however, are rarely considered in ecotoxicological testing strategies. The aim of this study was to systematically evaluate the suitability of an in vitro immuno-assay using selected fish immune parameters to screen for chemicals with known immunotoxic potential and to differentiate them from non-immunotoxicants. Non-stimulated and lipopolysaccharide-stimulated head kidney leukocytes of rainbow trout (Oncorhynchus mykiss) were exposed for 3 h or 19 h to chemicals with different modes of action. As immune parameters, phagocytosis activity, oxidative burst activity and cytokine transcription (IL-1β, TNFα, IL-10) were examined, accompanied by in silico modelling. The immunotoxicants dexamethasone, benzo(a)pyrene, ethinylestradiol and bisphenol A significantly altered the immune parameters at non-cytotoxic concentrations whereas diclofenac had only weak effects. However, the two baseline chemicals with no known immunotoxic potential, butanol and ethylene glycol, caused significant effects, too. From our results it appears that the in vitro fish leukocyte assay as performed in the present study has only a limited capacity for discriminating between immunotoxicants and non-immunotoxicants.
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26
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Lungu-Mitea S, Vogs C, Carlsson G, Montag M, Frieberg K, Oskarsson A, Lundqvist J. Modeling Bioavailable Concentrations in Zebrafish Cell Lines and Embryos Increases the Correlation of Toxicity Potencies across Test Systems. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:447-457. [PMID: 33320646 PMCID: PMC7872314 DOI: 10.1021/acs.est.0c04872] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 10/28/2020] [Accepted: 12/02/2020] [Indexed: 05/04/2023]
Abstract
Linking cellular toxicity to low-tier animal toxicity and beyond is crucial within the adverse outcome pathway concept and the 3R framework. This study aimed to determine and compare the bioavailable effect concentrations in zebrafish cell lines and embryos. Acute, short-term toxicity (48 h) of eight veterinary pharmaceuticals was measured in two zebrafish cell lines (hepatocytes, fibroblasts) and zebrafish embryos. Seven endpoints of cytotoxicity were recorded. The fish embryo acute toxicity test was modified by adding sublethal endpoints. Chemical distribution modeling (mass balance) was applied to compute the bioavailable compound concentrations in cells (Cfree) and embryos (Cint;aq) based on nominal effect concentrations (Cnom). Effect concentration ratios were calculated (cell effects/embryo effects). A low correlation was observed between cytotoxicity and embryo toxicity when nominal concentrations were used. Modeled bioavailable effect concentrations strongly increased correlations and placed regression lines close to the line of unity and axis origin. Cytotoxicity endpoints showed differences in sensitivity and predictability. The hepatocyte cell line depicted closer proximity to the embryo data. Conclusively, the high positive correlation between the cell- and embryo-based test systems emphasizes the appropriate modulation of toxicity when linked to bioavailable concentrations. Furthermore, it highlights the potential of fish cell lines to be utilized in integrated testing strategies.
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Affiliation(s)
- Sebastian Lungu-Mitea
- Department
of Biomedicine and Veterinary Public Health, Swedish University of Agricultural Sciences, Box 7028, SE-750 07 Uppsala, Sweden
| | - Carolina Vogs
- Department
of Biomedicine and Veterinary Public Health, Swedish University of Agricultural Sciences, Box 7028, SE-750 07 Uppsala, Sweden
| | - Gunnar Carlsson
- Department
of Biomedicine and Veterinary Public Health, Swedish University of Agricultural Sciences, Box 7028, SE-750 07 Uppsala, Sweden
| | - Maximiliane Montag
- Institute
for Environmental Research, RWTH Aachen, Worringerweg 1, D-52074 Aachen, Germany
| | - Kim Frieberg
- Department
of Biomedicine and Veterinary Public Health, Swedish University of Agricultural Sciences, Box 7028, SE-750 07 Uppsala, Sweden
| | - Agneta Oskarsson
- Department
of Biomedicine and Veterinary Public Health, Swedish University of Agricultural Sciences, Box 7028, SE-750 07 Uppsala, Sweden
| | - Johan Lundqvist
- Department
of Biomedicine and Veterinary Public Health, Swedish University of Agricultural Sciences, Box 7028, SE-750 07 Uppsala, Sweden
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27
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Tierbach A, Groh KJ, Schoenenberger R, Schirmer K, Suter MJF. Characterization of the Mercapturic Acid Pathway, an Important Phase II Biotransformation Route, in a Zebrafish Embryo Cell Line. Chem Res Toxicol 2020; 33:2863-2871. [PMID: 32990429 DOI: 10.1021/acs.chemrestox.0c00315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In view of the steadily increasing number of chemical compounds used in various products and applications, high-throughput toxicity screening techniques can help meeting the needs of 21st century risk assessment. Zebrafish (Danio rerio), especially its early life stages, are increasingly used in such screening efforts. In contrast, cell lines derived from this model organism have received less attention so far. A conceivable reason is the limited knowledge about their overall capacity to biotransform chemicals and the spectrum of expressed biotransformation pathways. One important biotransformation route is the mercapturic acid pathway, which protects organisms from harmful electrophilic compounds. The fully functional pathway involves a succession of several enzymatic reactions. To investigate the mercapturic acid pathway performance in the zebrafish embryonic cell line, PAC2, we analyzed the biotransformation products of the reactions comprising this pathway in the cells exposed to a nontoxic concentration of the reference substrate, 1-chloro-2,4-dinitrobenzene (CDNB). Additionally, we used targeted proteomics to measure the expression of cytosolic glutathione S-transferases (GSTs), the enzyme family catalyzing the first reaction in this pathway. Our results reveal that the PAC2 cell line expresses a fully functional mercapturic acid pathway. All but one of the intermediate CDNB biotransformation products were identified. The presence of the active mercapturic acid pathway in this cell line was further supported by the expression of a large palette of GST enzyme classes. Although the enzymes of the class alpha, one of the dominant GST classes in the zebrafish embryo, were not detected, this did not seem to affect the capacity of the PAC2 cells to biotransform CDNB. Our data provide an important contribution toward using zebrafish cell lines, specifically PAC2, for animal-free high- throughput screening in toxicology and chemical hazard assessment.
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Affiliation(s)
- Alena Tierbach
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland.,School of Architecture, Civil and Environmental Engineering, EPFL Lausanne, 1015 Lausanne, Switzerland
| | - Ksenia J Groh
- Food Packaging Forum Foundation, 8045 Zürich, Switzerland
| | - René Schoenenberger
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Kristin Schirmer
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland.,School of Architecture, Civil and Environmental Engineering, EPFL Lausanne, 1015 Lausanne, Switzerland.,Swiss Federal Institute of Technology, Department of Environmental Systems Science, ETH Zürich, 8092 Zürich, Switzerland
| | - Marc J-F Suter
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland.,Swiss Federal Institute of Technology, Department of Environmental Systems Science, ETH Zürich, 8092 Zürich, Switzerland
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28
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Zhang CY, Flor S, Ludewig G, Lehmler HJ. Atropselective Partitioning of Polychlorinated Biphenyls in a HepG2 Cell Culture System: Experimental and Modeling Results. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:13817-13827. [PMID: 33059451 PMCID: PMC7642102 DOI: 10.1021/acs.est.0c02508] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Cell culture models are used to study the toxicity of polychlorinated biphenyls (PCBs); however, it is typically unknown how much PCB enters the cells and, for chiral PCBs, if the partitioning is atropselective. We investigated the partitioning of racemic PCB 91, PCB 95, PCB 132, and PCB 136 in HepG2 cells following a 72 h incubation. PCBs were present in the cell culture medium (60.7-88.8%), cells (8.0-14.6%), and dishes (2.3-7.8%) and displayed atropisomeric enrichment in the cells (enantiomeric fraction [EF] = 0.55-0.77) and dishes (EF = 0.53-0.68). Polyparameter linear free energy relationships coupled with a composition-based model provided a good estimate of the PCB levels in the cells and cell culture medium. The free concentration was subsequently used to extrapolate from the nominal cell culture concentration to PCB tissue levels and vice versa. This approach can be used for in vitro-in vivo extrapolations for all 209 PCB congeners. However, this model (and modified models based on descriptors incorporating atropselective interactions, i.e., relative retention times on chiral columns) did not predict the atropselective partitioning in the cell culture system. Improved chemical descriptors that account for the atropselective binding of PCBs to biological macromolecules are, therefore, needed to predict the atropselective partitioning of PCBs in biological systems.
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Affiliation(s)
- Chun-Yun Zhang
- Department of Occupational and Environmental Health, The University of Iowa, Iowa City, Iowa 52242, United States
| | - Susanne Flor
- Department of Occupational and Environmental Health, The University of Iowa, Iowa City, Iowa 52242, United States
| | - Gabriele Ludewig
- Department of Occupational and Environmental Health, The University of Iowa, Iowa City, Iowa 52242, United States
| | - Hans-Joachim Lehmler
- Department of Occupational and Environmental Health, The University of Iowa, Iowa City, Iowa 52242, United States
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29
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Town RM, van Leeuwen HP. Uptake and Release Kinetics of Organic Contaminants Associated with Micro- and Nanoplastic Particles. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:10057-10067. [PMID: 32700905 DOI: 10.1021/acs.est.0c02297] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A generic theoretical framework is presented for describing the kinetics of uptake and release of organic compounds that associate with plastic particles. The underlying concepts account for the physicochemical features of the target organic compounds and the plastic particles. The developed framework builds on concepts established for dynamic speciation analysis by solid-phase microextraction and the size-dependent reactivity features of particulate complexants. The theoretical framework is applied to interpretation of literature data, thereby providing more rigorous insights into previous observations. The presented concepts enable predictions of the sink/source functioning of plastic particles and their impact on the dynamic chemical speciation of organic compounds in aqueous environmental media and within biota. Our results highlight the fundamental influence of particle size on the uptake and release kinetics. The findings call for a comprehensive description of the physicochemical features of plastic particles to be provided in experimental studies on micro- and nanoplastics in different types of aquatic environmental media.
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Affiliation(s)
- Raewyn M Town
- Systemic Physiological and Ecotoxicological Research (SPHERE), Department of Biology, Universiteit Antwerpen, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
- Physical Chemistry and Soft Matter, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Herman P van Leeuwen
- Physical Chemistry and Soft Matter, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
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30
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Escher BI, Henneberger L, König M, Schlichting R, Fischer FC. Cytotoxicity Burst? Differentiating Specific from Nonspecific Effects in Tox21 in Vitro Reporter Gene Assays. ENVIRONMENTAL HEALTH PERSPECTIVES 2020; 128:77007. [PMID: 32700975 PMCID: PMC7377237 DOI: 10.1289/ehp6664] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 06/16/2020] [Accepted: 07/02/2020] [Indexed: 05/03/2023]
Abstract
BACKGROUND High-throughput screening of chemicals with in vitro reporter gene assays in Tox21 has produced a large database on cytotoxicity and specific modes of action. However, the validity of some of the reported activities is questionable due to the "cytotoxicity burst," which refers to the supposition that many stress responses are activated in a nonspecific way at concentrations close to cell death. OBJECTIVES We propose a pragmatic method to identify whether reporter gene activation is specific or cytotoxicity-triggered by comparing the measured effects with baseline toxicity. METHODS Baseline toxicity, also termed narcosis, is the minimal toxicity any chemical causes. Quantitative structure-activity relationships (QSARs) developed for baseline toxicity in mammalian reporter gene cell lines served as anchors to define the chemical-specific threshold for the cytotoxicity burst and to evaluate the degree of specificity of the reporter gene activation. Measured 10% effect concentrations were related to measured or QSAR-predicted 10% cytotoxicity concentrations yielding specificity ratios (SR). We applied this approach to our own experimental data and to ∼ 8,000 chemicals that were tested in six of the high-throughput Tox21 reporter gene assays. RESULTS Confirmed baseline toxicants activated reporter gene activity around cytotoxic concentrations triggered by the cytotoxicity burst. In six Tox21 assays, 37%-87% of the active hits were presumably caused by the cytotoxicity burst (SR < 1 ) and only 2%-14% were specific with SR ≥ 10 against experimental cytotoxicity but 75%-97% were specific against baseline toxicity. This difference was caused by a large fraction of chemicals showing excess cytotoxicity. CONCLUSIONS The specificity analysis for measured in vitro effects identified whether a cytotoxicity burst had likely occurred. The SR-analysis not only prevented false positives, but it may also serve as measure for relative effect potency and can be used for quantitative in vitro-in vivo extrapolation and risk assessment of chemicals. https://doi.org/10.1289/EHP6664.
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Affiliation(s)
- Beate I. Escher
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
- Environmental Toxicology, Center for Applied Geoscience, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Luise Henneberger
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
| | - Maria König
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
| | - Rita Schlichting
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
| | - Fabian C. Fischer
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
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31
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Bergmann AJ, Simon E, Schifferli A, Schönborn A, Vermeirssen ELM. Estrogenic activity of food contact materials-evaluation of 20 chemicals using a yeast estrogen screen on HPTLC or 96-well plates. Anal Bioanal Chem 2020; 412:4527-4536. [PMID: 32458016 PMCID: PMC7329773 DOI: 10.1007/s00216-020-02701-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 04/08/2020] [Accepted: 05/11/2020] [Indexed: 11/29/2022]
Abstract
Food contact materials (FCM) may contain complex mixtures of estrogenic chemicals. A yeast estrogen screen performed on high performance thin-layer chromatography plates (planar-YES, P-YES) is promising for analysis of such mixtures, as it could allow for better elucidation of effects compared with established methods in microtiter plates. However, the P-YES has not been directly compared with established methods. We compared the performance of a microtiter plate YES (lyticase-YES, L-YES) to P-YES on silica gel HPTLC plates using 17β-estradiol (E2), 20 chemicals representative of migrants from plastic FCM, and three migrates of coated metal food cans. Effective doses (ED10, ED50) and estradiol equivalencies were calculated for each chemical. Thirteen chemicals had calculable EDs in the L-YES or P-YES, with average EDs 13-fold (range 0.63-36) more potent in P-YES than in the L-YES. Normalized to E2, the median estrogenicity was within 1.5-fold (0.43-8.8) between the assays. Therefore, P-YES was as or more sensitive than L-YES but potencies relative to E2 were comparable between assays. With chromatography, the P-YES detected estrogenicity in coated metal cans, effects that were unmeasurable in L-YES. With the sample preparation methods used in this study, both YES assays are sufficiently sensitive to detect bisphenol A below the specific migration limit for plastic packaging (0.05 mg/kg food). This study demonstrates that P-YES outperforms L-YES because it is more sensitive, provides comparable estradiol equivalents, and circumvents confounding mixture effects. The P-YES will be useful for routine monitoring of FCM and toxicant identification in problematic materials. Graphical abstract.
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Affiliation(s)
- Alan J Bergmann
- Swiss Centre for Applied Ecotoxicology, Eawag, Überlandstrasse 133, 8600, Dübendorf, Switzerland.
| | - Eszter Simon
- Swiss Centre for Applied Ecotoxicology, Eawag, Überlandstrasse 133, 8600, Dübendorf, Switzerland
| | - Andrea Schifferli
- Swiss Centre for Applied Ecotoxicology, Eawag, Überlandstrasse 133, 8600, Dübendorf, Switzerland
| | - Andreas Schönborn
- Zürich University of Applied Sciences, Grüental 14, 8820, Wädenswil, Switzerland
| | - Etiënne L M Vermeirssen
- Swiss Centre for Applied Ecotoxicology, Eawag, Überlandstrasse 133, 8600, Dübendorf, Switzerland
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32
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Xiao L, Zheng Z, Irgum K, Andersson PL. Studies of Emission Processes of Polymer Additives into Water Using Quartz Crystal Microbalance-A Case Study on Organophosphate Esters. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:4876-4885. [PMID: 32186175 PMCID: PMC7884016 DOI: 10.1021/acs.est.9b07607] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 03/08/2020] [Accepted: 03/18/2020] [Indexed: 06/10/2023]
Abstract
Plastic materials contain various additives, which can be released during the entire lifespan of plastics and pose a threat to the environment and human health. Despite our knowledge on leakage of additives from products, accurate and rapid approaches to study emission kinetics are largely lacking, in particular, methodologies that can provide in-depth understanding of polymer/additive interactions. Here, we report on a novel approach using quartz crystal microbalance (QCM) to measure emissions of additives to water from polymer films spin-coated on quartz crystals. The methodology, being accurate and reproducible with a standard error of ±2.4%, was applied to a range of organophosphate esters (OPEs) and polymers with varying physicochemical properties. The release of most OPEs reached an apparent steady-state within 10 h. The release curves for the studied OPEs could be fitted using a Weibull model, which shows that the release is a two-phase process with an initial fast phase driven by partitioning of OPEs readily available at or close to the polymer film surface, and a slower phase dominated by diffusion in the polymer. The kinetics of the first emission phase was mainly correlated with the hydrophobicity of the OPEs, whereas the diffusion phase was weakly correlated with molecular size. The developed QCM-based method for assessing and studying release of organic chemicals from a polymeric matrix is well suited for rapid screening of additives in efforts to identify more sustainable replacement polymer additives with lower emission potential.
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33
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Reiter EB, Jahnke A, König M, Siebert U, Escher BI. Influence of Co-Dosed Lipids from Biota Extracts on the Availability of Chemicals in In Vitro Cell-Based Bioassays. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:4240-4247. [PMID: 32118404 PMCID: PMC7144218 DOI: 10.1021/acs.est.9b07850] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 02/27/2020] [Accepted: 03/01/2020] [Indexed: 05/21/2023]
Abstract
Extraction of chemicals from biota leads to co-extraction of lipids. When dosing such extracts into in vitro bioassays, co-dosed lipids act as an additional phase that can reduce the bioavailability of the chemicals and the apparent sensitivity of the assay. Equilibrium partitioning between medium, cells, and co-dosed lipids was described with an existing equilibrium partitioning model for cell-based bioassays extended by an additional lipid phase. We experimentally investigated the influence of co-dosed lipids on the effects elicited by four test chemicals of different hydrophobicity in two bioassays, indicative of the aryl hydrocarbon receptor and oxidative stress response (AREc32). The partitioning model explained the effect of the test chemicals in the presence of spiked triolein within a factor of 0.33-5.83 between the measured and predicted effect concentration (EC). We applied the model to marine mammal blubber extracted with silicone. Extracts dosed in the AREc32 bioassay showed a linear increase of apparent EC with increasing lipid fraction. The partitioning model was used to interpret the role of the co-extracted lipid. A quantitative lipid correction of bioassay results in the presence of co-dosed lipids was possible for known compounds and defined mixtures, while we could only estimate a range for mixtures of unknown chemicals.
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Affiliation(s)
- Eva B. Reiter
- Department
Cell Toxicology, Helmholtz Centre for Environmental
Research—UFZ, Permoserstraße 15, 04318 Leipzig, Germany
- E-mail: . Phone: +49 341 235 1823. Fax: +49 341 235 1787
| | - Annika Jahnke
- Department
Cell Toxicology, Helmholtz Centre for Environmental
Research—UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Maria König
- Department
Cell Toxicology, Helmholtz Centre for Environmental
Research—UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Ursula Siebert
- Institute
for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, Werftstr. 6, 25761 Büsum, Germany
| | - Beate I. Escher
- Department
Cell Toxicology, Helmholtz Centre for Environmental
Research—UFZ, Permoserstraße 15, 04318 Leipzig, Germany
- Environmental
Toxicology, Center for Applied Geoscience, Eberhard Karls University Tübingen, Hölderlinstr. 12, 72074 Tübingen, Germany
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Fischer FC, Abele C, Henneberger L, Klüver N, König M, Mühlenbrink M, Schlichting R, Escher BI. Cellular Metabolism in High-Throughput In Vitro Reporter Gene Assays and Implications for the Quantitative In Vitro–In Vivo Extrapolation. Chem Res Toxicol 2020; 33:1770-1779. [DOI: 10.1021/acs.chemrestox.0c00037] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Fabian C. Fischer
- Department Cell Toxicology, Helmholtz Centre for Environmental Research—UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Cedric Abele
- Department Cell Toxicology, Helmholtz Centre for Environmental Research—UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Luise Henneberger
- Department Cell Toxicology, Helmholtz Centre for Environmental Research—UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Nils Klüver
- Department Bioanalytical Ecotoxicology, Helmholtz Centre for Environmental Research—UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Maria König
- Department Cell Toxicology, Helmholtz Centre for Environmental Research—UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Marie Mühlenbrink
- Department Cell Toxicology, Helmholtz Centre for Environmental Research—UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Rita Schlichting
- Department Cell Toxicology, Helmholtz Centre for Environmental Research—UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Beate I. Escher
- Department Cell Toxicology, Helmholtz Centre for Environmental Research—UFZ, Permoserstraße 15, 04318 Leipzig, Germany
- Centre for Applied Geoscience, Eberhard Karls University Tübingen, 72074 Tübingen, Germany
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Henneberger L, Mühlenbrink M, Heinrich DJ, Teixeira A, Nicol B, Escher BI. Experimental Validation of Mass Balance Models for in Vitro Cell-Based Bioassays. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:1120-1127. [PMID: 31852189 DOI: 10.1021/acs.est.9b06144] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The freely dissolved concentration in the assay medium (Cfree) and the total cellular concentration (Ccell) are essential input parameters for quantitative in vitro-to-in vivo extrapolations (QIVIVE), but available prediction tools for Cfree and Ccell have not been sufficiently validated with experimental data. In this study, medium-water distribution ratios (DFBS/w) and cell-water distribution ratios (Dcell/w) for four different cells lines were determined experimentally for 12 neutral and five ionizable chemicals. Literature data for seven organic acids were added to the dataset, leading to 24 chemicals in total. A mass balance model based on bovine serum albumin-water (DBSA/w) and liposome-water distribution ratios (Dlip/w) of the chemicals was used to calculate DFBS/w and Dcell/w. For all neutral and basic test chemicals, the mass balance model predicted DFBS/w and Dcell/w within a factor of 3 and 3.4, respectively, indicating that existing models can reliably predict Cfree and Ccell for these chemicals. For organic acids, a further refinement of the model will be required as large deviations between modeled and measured binding to assay medium and cells of up to a factor of 370 were found. Furthermore, saturation of medium proteins should be further explored for organic acids and neutral chemicals with moderate hydrophobicity.
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Affiliation(s)
- Luise Henneberger
- Department of Cell Toxicology , Helmholtz Centre for Environmental Research-UFZ , Permoserstr. 15 , 04318 Leipzig , Germany
| | - Marie Mühlenbrink
- Department of Cell Toxicology , Helmholtz Centre for Environmental Research-UFZ , Permoserstr. 15 , 04318 Leipzig , Germany
| | - Daniel J Heinrich
- Environmental Toxicology, Center for Applied Geoscience , Eberhard Karls University Tübingen , 72074 Tübingen , Germany
| | - Alexandre Teixeira
- Safety & Environmental Assurance Centre , Colworth Science Park , Sharnbrook , Bedfordshire MK44 1LQ , U.K
| | - Beate Nicol
- Safety & Environmental Assurance Centre , Colworth Science Park , Sharnbrook , Bedfordshire MK44 1LQ , U.K
| | - Beate I Escher
- Department of Cell Toxicology , Helmholtz Centre for Environmental Research-UFZ , Permoserstr. 15 , 04318 Leipzig , Germany
- Environmental Toxicology, Center for Applied Geoscience , Eberhard Karls University Tübingen , 72074 Tübingen , Germany
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Birch H, Kramer NI, Mayer P. Time-Resolved Freely Dissolved Concentrations of Semivolatile and Hydrophobic Test Chemicals in In Vitro Assays-Measuring High Losses and Crossover by Headspace Solid-Phase Microextraction. Chem Res Toxicol 2019; 32:1780-1790. [PMID: 31426631 DOI: 10.1021/acs.chemrestox.9b00133] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In vitro assays are normally conducted in plastic multiwell plates open to exchange with the ambient air. The concentration of test substances freely available to cells is often not known, can change over time, and is difficult to measure in the small volumes in microplates. However, even a well-characterized toxicological response is of limited value if it cannot be linked to a well-defined exposure level. The aim of this study was to develop and apply an approach for determining time-resolved freely dissolved concentrations of semivolatile and hydrophobic organic chemicals (SVHOCs) in in vitro assays: (1) free fractions were measured by a new medium dilution method and (2) time-resolved loss curves were obtained by measurements of total concentrations in 96-well plates during incubations at 37 °C. Headspace solid-phase microextraction was used as an analytical technique for 24 model chemicals spanning 6 chemical groups and 4-5 orders of magnitude in Kow and Kaw. Free fractions were >30% for chemicals with log Kow < 3.5 and then decreased with increasing log Kow. Medium concentrations declined significantly (>50%) within 24 h of incubation for all 20 chemicals having log Kow > 4 or log Kaw > -3.5 in serum-free medium. Losses of chemicals were lower for medium containing 10% fetal bovine serum, most significantly for chemicals with log Kow > 4. High crossover to neighboring wells also was observed below log Kow of 4 and log Kaw of -3.5. Sealing the well plates had limited effect on the losses but clearly reduced crossover. The high losses and crossover of most tested chemicals question the suitability of multiwell plates for in vitro testing of SVHOCs and call for (1) test systems that minimize losses, (2) methods to control in vitro exposure, (3) analytical confirmation of exposure, and (4) exposure control and confirmation being included in good in vitro reporting standards.
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Affiliation(s)
- Heidi Birch
- Department of Environmental Engineering , Technical University of Denmark , Bygningstorvet, Building 115 , 2800 Kongens Lyngby , Denmark
| | - Nynke I Kramer
- Institute for Risk Assessment Sciences , Utrecht University , 3508 TC Utrecht , The Netherlands
| | - Philipp Mayer
- Department of Environmental Engineering , Technical University of Denmark , Bygningstorvet, Building 115 , 2800 Kongens Lyngby , Denmark
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Escher BI, Glauch L, König M, Mayer P, Schlichting R. Baseline Toxicity and Volatility Cutoff in Reporter Gene Assays Used for High-Throughput Screening. Chem Res Toxicol 2019; 32:1646-1655. [PMID: 31313575 DOI: 10.1021/acs.chemrestox.9b00182] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Most studies using high-throughput in vitro cell-based bioassays tested chemicals up to a certain fixed concentration. It would be more appropriate to test up to concentrations predicted to elicit baseline toxicity because this is the minimal toxicity of every chemical. Baseline toxicity is also called narcosis and refers to nonspecific intercalation of chemicals in biological membranes, leading to loss of membrane structure and impaired functioning of membrane-related processes such as mitochondrial respiration. In cells, baseline toxicity manifests as cytotoxicity, which was quantified by a robust live-cell imaging method. Inhibitory concentrations for baseline toxicity varied by orders of magnitude between chemicals and were described by a simple quantitative structure activity relationship (QSAR) with the liposome-water partition constant as a sole descriptor. The QSAR equations were remarkably similar for eight reporter gene cell lines of different cellular origin, six of which were used in Tox21. Mass-balance models indicated constant critical membrane concentrations for all cells and all chemicals with a mean of 69 mmol·kglip-1(95% CI: 49-89), which is in the same range as for bacteria and aquatic organisms and consistent with the theory of critical membrane burden of narcosis. The challenge of developing baseline QSARs for cell lines is that many confirmed baseline toxicants are rather volatile. We deduced from cytotoxicity experiments with semi-volatile chemicals that only chemicals with medium-air partition constants >10,000 L/L can be tested in standard robotic setups without appreciable loss of effect. Chemicals just below that cutoff showed crossover effects in neighboring wells, whereas the effects of chemicals with lower medium-air partition constants were plainly lost. Applying the "volatility cut-off" to >8000 chemicals tested in Tox21 indicated that approximately 20% of Tox21 chemicals could have partially been lost during the experiments. We recommend applying the baseline QSARs together with volatility cut-offs for experimental planning of reporter gene assays, that is, to dose only chemicals with medium-air partition constants >10,000 at concentrations up to the baseline toxicity level.
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Affiliation(s)
- Beate I Escher
- Department of Cell Toxicology , Helmholtz Centre for Environmental Research - UFZ , Permoserstr. 15 , DE-04318 Leipzig , Germany.,Environmental Toxicology, Center for Applied Geoscience , Eberhard Karls University Tübingen , Hölderlinstr. 12 , DE-72074 Tübingen , Germany
| | - Lisa Glauch
- Department of Cell Toxicology , Helmholtz Centre for Environmental Research - UFZ , Permoserstr. 15 , DE-04318 Leipzig , Germany
| | - Maria König
- Department of Cell Toxicology , Helmholtz Centre for Environmental Research - UFZ , Permoserstr. 15 , DE-04318 Leipzig , Germany
| | - Philipp Mayer
- Department of Environmental Engineering , Technical University of Denmark , Bygningstorvet 115 , DK-2800 Kongens Lyngby , Denmark
| | - Rita Schlichting
- Department of Cell Toxicology , Helmholtz Centre for Environmental Research - UFZ , Permoserstr. 15 , DE-04318 Leipzig , Germany
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Fischer FC, Henneberger L, Schlichting R, Escher BI. How To Improve the Dosing of Chemicals in High-Throughput in Vitro Mammalian Cell Assays. Chem Res Toxicol 2019; 32:1462-1468. [DOI: 10.1021/acs.chemrestox.9b00167] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Fabian C. Fischer
- Department Cell Toxicology, Helmholtz Centre for Environmental Research - UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Luise Henneberger
- Department Cell Toxicology, Helmholtz Centre for Environmental Research - UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Rita Schlichting
- Department Cell Toxicology, Helmholtz Centre for Environmental Research - UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Beate I. Escher
- Department Cell Toxicology, Helmholtz Centre for Environmental Research - UFZ, Permoserstraße 15, 04318 Leipzig, Germany
- Centre for Applied Geoscience, Eberhard Karls University Tübingen, 72074 Tübingen, Germany
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Henneberger L, Mühlenbrink M, König M, Schlichting R, Fischer FC, Escher BI. Quantification of freely dissolved effect concentrations in in vitro cell-based bioassays. Arch Toxicol 2019; 93:2295-2305. [DOI: 10.1007/s00204-019-02498-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Accepted: 06/17/2019] [Indexed: 02/05/2023]
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