101
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Pearce RG, Setzer RW, Davis JL, Wambaugh JF. Evaluation and calibration of high-throughput predictions of chemical distribution to tissues. J Pharmacokinet Pharmacodyn 2017; 44:549-565. [PMID: 29032447 PMCID: PMC6186149 DOI: 10.1007/s10928-017-9548-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 09/30/2017] [Indexed: 12/25/2022]
Abstract
Toxicokinetics (TK) provides critical information for integrating chemical toxicity and exposure assessments in order to determine potential chemical risk (i.e., the margin between toxic doses and plausible exposures). For thousands of chemicals that are present in our environment, in vivo TK data are lacking. The publicly available R package "httk" (version 1.8, named for "high throughput TK") draws from a database of in vitro data and physico-chemical properties in order to run physiologically-based TK (PBTK) models for 553 compounds. The PBTK model parameters include tissue:plasma partition coefficients (Kp) which the httk software predicts using the model of Schmitt (Toxicol In Vitro 22 (2):457-467, 2008). In this paper we evaluated and modified httk predictions, and quantified confidence using in vivo literature data. We used 964 rat Kp measured by in vivo experiments for 143 compounds. Initially, predicted Kp were significantly larger than measured Kp for many lipophilic compounds (log10 octanol:water partition coefficient > 3). Hence the approach for predicting Kp was revised to account for possible deficiencies in the in vitro protein binding assay, and the method for predicting membrane affinity was revised. These changes yielded improvements ranging from a factor of 10 to nearly a factor of 10,000 for 83 Kp across 23 compounds with only 3 Kp worsening by more than a factor of 10. The vast majority (92%) of Kp were predicted within a factor of 10 of the measured value (overall root mean squared error of 0.59 on log10-transformed scale). After applying the adjustments, regressions were performed to calibrate and evaluate the predictions for 12 tissues. Predictions for some tissues (e.g., spleen, bone, gut, lung) were observed to be better than predictions for other tissues (e.g., skin, brain, fat), indicating that confidence in the application of in silico tools to predict chemical partitioning varies depending upon the tissues involved. Our calibrated model was then evaluated using a second data set of human in vivo measurements of volume of distribution (Vss) for 498 compounds reviewed by Obach et al. (Drug Metab Dispos 36(7):1385-1405, 2008). We found that calibration of the model improved performance: a regression of the measured values as a function of the predictions has a slope of 1.03, intercept of - 0.04, and R2 of 0.43. Through careful evaluation of predictive methods for chemical partitioning into tissues, we have improved and calibrated these methods and quantified confidence for TK predictions in humans and rats.
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Affiliation(s)
- Robert G Pearce
- National Center for Computational Toxicology, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, 109 T.W. Alexander Dr, Durham, NC, 27711, USA
- Oak Ridge Institute for Science and Education, Oak Ridge, TN, 37831, USA
| | - R Woodrow Setzer
- National Center for Computational Toxicology, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, 109 T.W. Alexander Dr, Durham, NC, 27711, USA
| | - Jimena L Davis
- National Center for Computational Toxicology, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, 109 T.W. Alexander Dr, Durham, NC, 27711, USA
- Syngenta, Research Triangle Park, NC, 27709, USA
| | - John F Wambaugh
- National Center for Computational Toxicology, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, 109 T.W. Alexander Dr, Durham, NC, 27711, USA.
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102
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Nymark P, Rieswijk L, Ehrhart F, Jeliazkova N, Tsiliki G, Sarimveis H, Evelo CT, Hongisto V, Kohonen P, Willighagen E, Grafström RC. A Data Fusion Pipeline for Generating and Enriching Adverse Outcome Pathway Descriptions. Toxicol Sci 2017; 162:264-275. [DOI: 10.1093/toxsci/kfx252] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Penny Nymark
- Institute of Environmental Medicine, Karolinska Institutet, 171 77 Stockholm, Sweden
- Department of Toxicology, Misvik Biology, 20520 Turku, Finland
| | - Linda Rieswijk
- Department of Bioinformatics, NUTRIM, Maastricht University, 6200MD Maastricht, The Netherlands
- Division of Environmental Health Sciences, School of Public Health, University of California, 94720-7360 Berkeley, California, United States
| | - Friederike Ehrhart
- Department of Bioinformatics, NUTRIM, Maastricht University, 6200MD Maastricht, The Netherlands
| | | | - Georgia Tsiliki
- School of Chemical Engineering, National Technical University of Athens, 157 80 Athens, Greece
- Institute for the Management of Information Systems, ATHENA Research and Innovation Centre, 151 25 Athens, Greece
| | - Haralambos Sarimveis
- School of Chemical Engineering, National Technical University of Athens, 157 80 Athens, Greece
| | - Chris T Evelo
- Department of Bioinformatics, NUTRIM, Maastricht University, 6200MD Maastricht, The Netherlands
| | - Vesa Hongisto
- Department of Toxicology, Misvik Biology, 20520 Turku, Finland
| | - Pekka Kohonen
- Institute of Environmental Medicine, Karolinska Institutet, 171 77 Stockholm, Sweden
- Department of Toxicology, Misvik Biology, 20520 Turku, Finland
| | - Egon Willighagen
- Department of Bioinformatics, NUTRIM, Maastricht University, 6200MD Maastricht, The Netherlands
| | - Roland C Grafström
- Institute of Environmental Medicine, Karolinska Institutet, 171 77 Stockholm, Sweden
- Department of Toxicology, Misvik Biology, 20520 Turku, Finland
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103
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Berggren E, White A, Ouedraogo G, Paini A, Richarz AN, Bois FY, Exner T, Leite S, Grunsven LAV, Worth A, Mahony C. Ab initio chemical safety assessment: A workflow based on exposure considerations and non-animal methods. COMPUTATIONAL TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2017; 4:31-44. [PMID: 29214231 PMCID: PMC5695905 DOI: 10.1016/j.comtox.2017.10.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 10/09/2017] [Accepted: 10/10/2017] [Indexed: 12/12/2022]
Abstract
We describe and illustrate a workflow for chemical safety assessment that completely avoids animal testing. The workflow, which was developed within the SEURAT-1 initiative, is designed to be applicable to cosmetic ingredients as well as to other types of chemicals, e.g. active ingredients in plant protection products, biocides or pharmaceuticals. The aim of this work was to develop a workflow to assess chemical safety without relying on any animal testing, but instead constructing a hypothesis based on existing data, in silico modelling, biokinetic considerations and then by targeted non-animal testing. For illustrative purposes, we consider a hypothetical new ingredient x as a new component in a body lotion formulation. The workflow is divided into tiers in which points of departure are established through in vitro testing and in silico prediction, as the basis for estimating a safe external dose in a repeated use scenario. The workflow includes a series of possible exit (decision) points, with increasing levels of confidence, based on the sequential application of the Threshold of Toxicological (TTC) approach, read-across, followed by an "ab initio" assessment, in which chemical safety is determined entirely by new in vitro testing and in vitro to in vivo extrapolation by means of mathematical modelling. We believe that this workflow could be applied as a tool to inform targeted and toxicologically relevant in vitro testing, where necessary, and to gain confidence in safety decision making without the need for animal testing.
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Affiliation(s)
- Elisabet Berggren
- Chemical Safety and Alternative Methods Unit, & EURL ECVAM, Directorate F – Health, Consumers and Reference Materials, Joint Research Centre, European Commission, Ispra, Italy
| | | | | | - Alicia Paini
- Chemical Safety and Alternative Methods Unit, & EURL ECVAM, Directorate F – Health, Consumers and Reference Materials, Joint Research Centre, European Commission, Ispra, Italy
| | - Andrea-Nicole Richarz
- Chemical Safety and Alternative Methods Unit, & EURL ECVAM, Directorate F – Health, Consumers and Reference Materials, Joint Research Centre, European Commission, Ispra, Italy
| | | | | | - Sofia Leite
- Liver Cell Biology Laboratory, Vrije Universiteit Brussel, Brussels, Belgium
| | - Leo A. van Grunsven
- Liver Cell Biology Laboratory, Vrije Universiteit Brussel, Brussels, Belgium
| | - Andrew Worth
- Chemical Safety and Alternative Methods Unit, & EURL ECVAM, Directorate F – Health, Consumers and Reference Materials, Joint Research Centre, European Commission, Ispra, Italy
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104
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Cote IL, McCullough SD, Hines RN, Vandenberg JJ. Application of epigenetic data in human health risk assessment. CURRENT OPINION IN TOXICOLOGY 2017; 6:71-78. [PMID: 29333520 DOI: 10.1016/j.cotox.2017.09.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Despite the many recent advances in the field of epigenetics, application of this knowledge in environmental health risk assessment has been limited. In this paper, we identify opportunities for application of epigenetic data to support health risk assessment. We consider current applications and present a vision for the future.
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Affiliation(s)
- Ila L Cote
- National Center for Environmental Assessment, Office of Research and Development, United States Environmental Protection Agency, Washington DC 22202, USA
| | - Shaun D McCullough
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, NC 27711, USA
| | - Ronald N Hines
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, NC 27711, USA
| | - John J Vandenberg
- National Center for Environmental Assessment, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, NC 27711, USA
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105
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LaRocca J, Johnson KJ, LeBaron MJ, Rasoulpour RJ. The interface of epigenetics and toxicology in product safety assessment. CURRENT OPINION IN TOXICOLOGY 2017. [DOI: 10.1016/j.cotox.2017.11.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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106
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Integration of the TGx-28.65 genomic biomarker with the flow cytometry micronucleus test to assess the genotoxicity of disperse orange and 1,2,4-benzenetriol in human TK6 cells. Mutat Res 2017; 806:51-62. [PMID: 29017062 DOI: 10.1016/j.mrfmmm.2017.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 07/21/2017] [Accepted: 09/10/2017] [Indexed: 12/13/2022]
Abstract
In vitro gene expression signatures to predict toxicological responses can provide mechanistic context for regulatory testing. We previously developed the TGx-28.65 genomic biomarker from a database of gene expression profiles derived from human TK6 cells exposed to 28 well-known compounds. The biomarker comprises 65 genes that can classify chemicals as DNA damaging or non-DNA damaging. In this study, we applied the TGx-28.65 genomic biomarker in parallel with the in vitro micronucleus (MN) assay to determine if two chemicals of regulatory interest at Health Canada, disperse orange (DO: the orange azo dye 3-[[4-[(4-Nitrophenyl)azo]phenyl] benzylamino]propanenitrile) and 1,2,4-benzenetriol (BT: a metabolite of benzene) are genotoxic or non-genotoxic. Both chemicals caused dose-dependent declines in relative survival and increases in apoptosis. A strong significant increase in MN induction was observed for all concentrations of BT; the top two concentrations of DO also caused a statistically significant increase in MN, but these increases were <2-fold above controls. TGx-28.65 analysis classified BT as genotoxic at all three concentrations and DO as genotoxic at the mid and high concentrations. Thus, although DO only caused a small increase in MN, this response was sufficient to induce a cellular DNA damage response. Benchmark dose modeling confirmed that BT is much more potent than DO. The results strongly suggest that follow-up work is required to assess whether DO and BT are also genotoxic in vivo. This is particularly important for DO, which may require metabolic activation by bacterial gut flora to fully induce its genotoxic potential. Our previously published data and this proof of concept study suggest that the TGx-28.65 genomic biomarker has the potential to add significant value to existing approaches used to assess genotoxicity.
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107
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Transcriptional profiling of male F344 rats suggests the involvement of calcium signaling in the mode of action of acrylamide-induced thyroid cancer. Food Chem Toxicol 2017; 107:186-200. [DOI: 10.1016/j.fct.2017.06.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 06/06/2017] [Accepted: 06/08/2017] [Indexed: 12/21/2022]
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108
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Gabbert S, Leontaridou M, Landsiedel R. A Critical Review of Adverse Outcome Pathway-Based Concepts and Tools for Integrating Information from Nonanimal Testing Methods: The Case of Skin Sensitization. ACTA ACUST UNITED AC 2017. [DOI: 10.1089/aivt.2017.0015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Silke Gabbert
- Environmental Economics and Natural Resources Group, Wageningen University, Wageningen, The Netherlands
| | - Maria Leontaridou
- Environmental Economics and Natural Resources Group, Wageningen University, Wageningen, The Netherlands
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109
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Ring CL, Pearce RG, Setzer RW, Wetmore BA, Wambaugh JF. Identifying populations sensitive to environmental chemicals by simulating toxicokinetic variability. ENVIRONMENT INTERNATIONAL 2017; 106:105-118. [PMID: 28628784 PMCID: PMC6116525 DOI: 10.1016/j.envint.2017.06.004] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 06/01/2017] [Accepted: 06/02/2017] [Indexed: 05/17/2023]
Abstract
The thousands of chemicals present in the environment (USGAO, 2013) must be triaged to identify priority chemicals for human health risk research. Most chemicals have little of the toxicokinetic (TK) data that are necessary for relating exposures to tissue concentrations that are believed to be toxic. Ongoing efforts have collected limited, in vitro TK data for a few hundred chemicals. These data have been combined with biomonitoring data to estimate an approximate margin between potential hazard and exposure. The most "at risk" 95th percentile of adults have been identified from simulated populations that are generated either using standard "average" adult human parameters or very specific cohorts such as Northern Europeans. To better reflect the modern U.S. population, we developed a population simulation using physiologies based on distributions of demographic and anthropometric quantities from the most recent U.S. Centers for Disease Control and Prevention National Health and Nutrition Examination Survey (NHANES) data. This allowed incorporation of inter-individual variability, including variability across relevant demographic subgroups. Variability was analyzed with a Monte Carlo approach that accounted for the correlation structure in physiological parameters. To identify portions of the U.S. population that are more at risk for specific chemicals, physiologic variability was incorporated within an open-source high-throughput (HT) TK modeling framework. We prioritized 50 chemicals based on estimates of both potential hazard and exposure. Potential hazard was estimated from in vitro HT screening assays (i.e., the Tox21 and ToxCast programs). Bioactive in vitro concentrations were extrapolated to doses that produce equivalent concentrations in body tissues using a reverse dosimetry approach in which generic TK models are parameterized with: 1) chemical-specific parameters derived from in vitro measurements and predicted from chemical structure; and 2) with physiological parameters for a virtual population. For risk-based prioritization of chemicals, predicted bioactive equivalent doses were compared to demographic-specific inferences of exposure rates that were based on NHANES urinary analyte biomonitoring data. The inclusion of NHANES-derived inter-individual variability decreased predicted bioactive equivalent doses by 12% on average for the total population when compared to previous methods. However, for some combinations of chemical and demographic groups the margin was reduced by as much as three quarters. This TK modeling framework allows targeted risk prioritization of chemicals for demographic groups of interest, including potentially sensitive life stages and subpopulations.
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Affiliation(s)
- Caroline L Ring
- Oak Ridge Institute for Science and Education, Oak Ridge, TN 37831, United States; National Center for Computational Toxicology, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, NC 27711, United States
| | - Robert G Pearce
- Oak Ridge Institute for Science and Education, Oak Ridge, TN 37831, United States; National Center for Computational Toxicology, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, NC 27711, United States
| | - R Woodrow Setzer
- National Center for Computational Toxicology, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, NC 27711, United States
| | - Barbara A Wetmore
- ScitoVation, LLC, Research Triangle Park, NC, United States; National Exposure Research Laboratory, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, NC 27711, United States
| | - John F Wambaugh
- National Center for Computational Toxicology, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, NC 27711, United States.
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110
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Zaunbrecher V, Beryt E, Parodi D, Telesca D, Doherty J, Malloy T, Allard P. Has Toxicity Testing Moved into the 21st Century? A Survey and Analysis of Perceptions in the Field of Toxicology. ENVIRONMENTAL HEALTH PERSPECTIVES 2017; 125:087024. [PMID: 28934728 PMCID: PMC5783667 DOI: 10.1289/ehp1435] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 06/15/2017] [Accepted: 06/17/2017] [Indexed: 05/22/2023]
Abstract
BACKGROUND Ten years ago, leaders in the field of toxicology called for a transformation of the discipline and a shift from primarily relying on traditional animal testing to incorporating advances in biotechnology and predictive methodologies into alternative testing strategies (ATS). Governmental agencies and academic and industry partners initiated programs to support such a transformation, but a decade later, the outcomes of these efforts are not well understood. OBJECTIVES We aimed to assess the use of ATS and the perceived barriers and drivers to their adoption by toxicologists and by others working in, or closely linked with, the field of toxicology. METHODS We surveyed 1,381 toxicologists and experts in associated fields regarding the viability and use of ATS and the perceived barriers and drivers of ATS for a range of applications. We performed ranking, hierarchical clustering, and correlation analyses of the survey data. RESULTS Many respondents indicated that they were already using ATS, or believed that ATS were already viable approaches, for toxicological assessment of one or more end points in their primary area of interest or concern (26-86%, depending on the specific ATS/application pair). However, the proportions of respondents reporting use of ATS in the previous 12 mo were smaller (4.5-41%). Concern about regulatory acceptance was the most commonly cited factor inhibiting the adoption of ATS, and a variety of technical concerns were also cited as significant barriers to ATS viability. The factors most often cited as playing a significant role (currently or in the future) in driving the adoption of ATS were the need for expedited toxicology information, the need for reduced toxicity testing costs, demand by regulatory agencies, and ethical or moral concerns. CONCLUSIONS Our findings indicate that the transformation of the field of toxicology is partly implemented, but significant barriers to acceptance and adoption remain. https://doi.org/10.1289/EHP1435.
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Affiliation(s)
- Virginia Zaunbrecher
- Sustainable Technology and Policy Program, University of California, Los Angeles , Los Angeles, California, USA
- School of Law, University of California, Los Angeles , Los Angeles, California, USA
| | - Elizabeth Beryt
- Luskin School of Public Affairs, University of California, Los Angeles , Los Angeles, California, USA
| | - Daniela Parodi
- Institute for Society and Genetics, University of California, Los Angeles , Los Angeles, California, USA
| | - Donatello Telesca
- Department of Biostatistics, UCLA Fielding School of Public Health, University of California, Los Angeles , Los Angeles, California, USA
| | - Joseph Doherty
- School of Law, University of California, Los Angeles , Los Angeles, California, USA
| | - Timothy Malloy
- Sustainable Technology and Policy Program, University of California, Los Angeles , Los Angeles, California, USA
- School of Law, University of California, Los Angeles , Los Angeles, California, USA
- Department of Environmental Health Sciences, UCLA Fielding School of Public Health, University of California, Los Angeles , Los Angeles, California, USA
| | - Patrick Allard
- Sustainable Technology and Policy Program, University of California, Los Angeles , Los Angeles, California, USA
- Institute for Society and Genetics, University of California, Los Angeles , Los Angeles, California, USA
- Department of Environmental Health Sciences, UCLA Fielding School of Public Health, University of California, Los Angeles , Los Angeles, California, USA
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111
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Jackson MA, Yang L, Lea I, Rashid A, Kuo B, Williams A, Lyn Yauk C, Fostel J. The TGx-28.65 biomarker online application for analysis of transcriptomics data to identify DNA damage-inducing chemicals in human cell cultures. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2017; 58:529-535. [PMID: 28766826 DOI: 10.1002/em.22114] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 06/19/2017] [Accepted: 06/20/2017] [Indexed: 06/07/2023]
Abstract
The TGx-28.65 biomarker is a 65-gene expression profile generated from testing 28 model chemicals (13 that cause DNA damage and 15 that do not) in human TK6 cells. It is used to predict whether a chemical induces DNA damage or not. We expanded availability to the biomarker by developing the online TGx-28.65 biomarker application for predicting the DNA damage inducing (DDI) potential of suspect toxicants tested in p53-proficient human cells and assessing putative mode(s) of action (MOA). Applications like this that analyse gene expression data to predict the hazard potential of test chemicals hold great promise for risk assessment paradigms. The TGx-28.65 biomarker interfaces with an analytical tool to predict the probability that a test chemical can directly or indirectly induce DNA damage. User submitted in vitro microarray data are compared to the 28-chemical x 65-gene signature profile and the probability that the data fit the profile for a DDI or a non-DDI (NDDI) chemical is calculated. The results are displayed in the Results Table, which includes the classification probability and hyperlinks to view heatmaps, hierarchical clustering, and principal component analyses of user-input data in the context of the reference profile. The heatmaps and cluster plots, along with the corresponding text data files of fold changes in gene expression and Euclidean distances can be downloaded. Review of the test chemical data in relationship to the biomarker allows rapid identification of key gene alterations associated with DNA damage as well as chemicals in the reference set that produced a similar response. Environ. Mol. Mutagen. 58:529-535, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
| | - Longlong Yang
- DS Technologies, Inc., Research Triangle Park, North Carolina
| | - Isabel Lea
- ASRC Federal - Vistronix, Morrisville, North Carolina
| | - Asif Rashid
- ASRC Federal - Vistronix, Morrisville, North Carolina
| | - Byron Kuo
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, Canada
| | - Andrew Williams
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, Canada
| | - Carole Lyn Yauk
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, Canada
| | - Jennifer Fostel
- National Institute of Environmental Health Sciences/National Institutes of Health, National Toxicology Program, Research Triangle Park, North Carolina
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112
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Pearce RG, Setzer RW, Strope CL, Wambaugh JF, Sipes NS. httk: R Package for High-Throughput Toxicokinetics. J Stat Softw 2017; 79:1-26. [PMID: 30220889 DOI: 10.18637/jss.v079.i04.submit] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
Thousands of chemicals have been profiled by high-throughput screening programs such as ToxCast and Tox21; these chemicals are tested in part because most of them have limited or no data on hazard, exposure, or toxicokinetics. Toxicokinetic models aid in predicting tissue concentrations resulting from chemical exposure, and a "reverse dosimetry" approach can be used to predict exposure doses sufficient to cause tissue concentrations that have been identified as bioactive by high-throughput screening. We have created four toxicokinetic models within the R software package httk. These models are designed to be parameterized using high-throughput in vitro data (plasma protein binding and hepatic clearance), as well as structure-derived physicochemical properties and species-specific physiological data. The package contains tools for Monte Carlo sampling and reverse dosimetry along with functions for the analysis of concentration vs. time simulations. The package can currently use human in vitro data to make predictions for 553 chemicals in humans, rats, mice, dogs, and rabbits, including 94 pharmaceuticals and 415 ToxCast chemicals. For 67 of these chemicals, the package includes rat-specific in vitro data. This package is structured to be augmented with additional chemical data as they become available. Package httk enables the inclusion of toxicokinetics in the statistical analysis of chemicals undergoing high-throughput screening.
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Affiliation(s)
- Robert G Pearce
- U.S. Environmental Protection Agency 109 T.W. Alexander Dr. Mail Code D143-02 Research Triangle Park, NC 27711, United States of America URL: http://www.epa.gov/ncct/
| | - R Woodrow Setzer
- U.S. Environmental Protection Agency 109 T.W. Alexander Dr. Mail Code D143-02 Research Triangle Park, NC 27711, United States of America URL: http://www.epa.gov/ncct/
| | - Cory L Strope
- U.S. Environmental Protection Agency 109 T.W. Alexander Dr. Mail Code D143-02 Research Triangle Park, NC 27711, United States of America URL: http://www.epa.gov/ncct/
| | - John F Wambaugh
- U.S. Environmental Protection Agency 109 T.W. Alexander Dr. Mail Code D143-02 Research Triangle Park, NC 27711, United States of America URL: http://www.epa.gov/ncct/
| | - Nisha S Sipes
- Division of the National Toxicology Program National Institute of Environmental Health Sciences 111 T.W. Alexander Dr., ML: K2-17 Research Triangle Park, NC 27709, United States of America URL: http://www.niehs.nih.gov/research/atniehs/labs/bmsb/
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113
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Pearce RG, Setzer RW, Strope CL, Wambaugh JF, Sipes NS. httk: R Package for High-Throughput Toxicokinetics. J Stat Softw 2017; 79:1-26. [PMID: 30220889 PMCID: PMC6134854 DOI: 10.18637/jss.v079.i04] [Citation(s) in RCA: 167] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Thousands of chemicals have been profiled by high-throughput screening programs such as ToxCast and Tox21; these chemicals are tested in part because most of them have limited or no data on hazard, exposure, or toxicokinetics. Toxicokinetic models aid in predicting tissue concentrations resulting from chemical exposure, and a "reverse dosimetry" approach can be used to predict exposure doses sufficient to cause tissue concentrations that have been identified as bioactive by high-throughput screening. We have created four toxicokinetic models within the R software package httk. These models are designed to be parameterized using high-throughput in vitro data (plasma protein binding and hepatic clearance), as well as structure-derived physicochemical properties and species-specific physiological data. The package contains tools for Monte Carlo sampling and reverse dosimetry along with functions for the analysis of concentration vs. time simulations. The package can currently use human in vitro data to make predictions for 553 chemicals in humans, rats, mice, dogs, and rabbits, including 94 pharmaceuticals and 415 ToxCast chemicals. For 67 of these chemicals, the package includes rat-specific in vitro data. This package is structured to be augmented with additional chemical data as they become available. Package httk enables the inclusion of toxicokinetics in the statistical analysis of chemicals undergoing high-throughput screening.
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Affiliation(s)
- Robert G Pearce
- U.S. Environmental Protection Agency 109 T.W. Alexander Dr. Mail Code D143-02 Research Triangle Park, NC 27711, United States of America URL: http://www.epa.gov/ncct/
| | - R Woodrow Setzer
- U.S. Environmental Protection Agency 109 T.W. Alexander Dr. Mail Code D143-02 Research Triangle Park, NC 27711, United States of America URL: http://www.epa.gov/ncct/
| | - Cory L Strope
- U.S. Environmental Protection Agency 109 T.W. Alexander Dr. Mail Code D143-02 Research Triangle Park, NC 27711, United States of America URL: http://www.epa.gov/ncct/
| | - John F Wambaugh
- U.S. Environmental Protection Agency 109 T.W. Alexander Dr. Mail Code D143-02 Research Triangle Park, NC 27711, United States of America URL: http://www.epa.gov/ncct/
| | - Nisha S Sipes
- Division of the National Toxicology Program National Institute of Environmental Health Sciences 111 T.W. Alexander Dr., ML: K2-17 Research Triangle Park, NC 27709, United States of America URL: http://www.niehs.nih.gov/research/atniehs/labs/bmsb/
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The sbv IMPROVER Systems Toxicology Computational Challenge: Identification of Human and Species-Independent Blood Response Markers as Predictors of Smoking Exposure and Cessation Status. ACTA ACUST UNITED AC 2017; 5:38-51. [PMID: 30221212 DOI: 10.1016/j.comtox.2017.07.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Cigarette smoking entails chronic exposure to a mixture of harmful chemicals that trigger molecular changes over time, and is known to increase the risk of developing diseases. Risk assessment in the context of 21st century toxicology relies on the elucidation of mechanisms of toxicity and the identification of exposure response markers, usually from high-throughput data, using advanced computational methodologies. The sbv IMPROVER Systems Toxicology computational challenge (Fall 2015-Spring 2016) aimed to evaluate whether robust and sparse (≤40 genes) human (sub-challenge 1, SC1) and species-independent (sub-challenge 2, SC2) exposure response markers (so called gene signatures) could be extracted from human and mouse blood transcriptomics data of current (S), former (FS) and never (NS) smoke-exposed subjects as predictors of smoking and cessation status. Best-performing computational methods were identified by scoring anonymized participants' predictions. Worldwide participation resulted in 12 (SC1) and six (SC2) final submissions qualified for scoring. The results showed that blood gene expression data were informative to predict smoking exposure (i.e. discriminating smoker versus never or former smokers) status in human and across species with a high level of accuracy. By contrast, the prediction of cessation status (i.e. distinguishing FS from NS) remained challenging, as reflected by lower classification performances. Participants successfully developed inductive predictive models and extracted human and species-independent gene signatures, including genes with high consensus across teams. Post-challenge analyses highlighted "feature selection" as a key step in the process of building a classifier and confirmed the importance of testing a gene signature in independent cohorts to ensure the generalized applicability of a predictive model at a population-based level. In conclusion, the Systems Toxicology challenge demonstrated the feasibility of extracting a consistent blood-based smoke exposure response gene signature and further stressed the importance of independent and unbiased data and method evaluations to provide confidence in systems toxicology-based scientific conclusions.
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Kohonen P, Parkkinen JA, Willighagen EL, Ceder R, Wennerberg K, Kaski S, Grafström RC. A transcriptomics data-driven gene space accurately predicts liver cytopathology and drug-induced liver injury. Nat Commun 2017; 8:15932. [PMID: 28671182 PMCID: PMC5500850 DOI: 10.1038/ncomms15932] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 05/15/2017] [Indexed: 01/17/2023] Open
Abstract
Predicting unanticipated harmful effects of chemicals and drug molecules is a difficult and costly task. Here we utilize a 'big data compacting and data fusion'-concept to capture diverse adverse outcomes on cellular and organismal levels. The approach generates from transcriptomics data set a 'predictive toxicogenomics space' (PTGS) tool composed of 1,331 genes distributed over 14 overlapping cytotoxicity-related gene space components. Involving ∼2.5 × 108 data points and 1,300 compounds to construct and validate the PTGS, the tool serves to: explain dose-dependent cytotoxicity effects, provide a virtual cytotoxicity probability estimate intrinsic to omics data, predict chemically-induced pathological states in liver resulting from repeated dosing of rats, and furthermore, predict human drug-induced liver injury (DILI) from hepatocyte experiments. Analysing 68 DILI-annotated drugs, the PTGS tool outperforms and complements existing tests, leading to a hereto-unseen level of DILI prediction accuracy.
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Affiliation(s)
- Pekka Kohonen
- Institute of Environmental Medicine, Karolinska Institutet, Nobels väg 13, Box 210, SE-17177 Stockholm, Sweden
| | - Juuso A Parkkinen
- Helsinki Institute for Information Technology HIIT, Department of Computer Science, Aalto University, Konemiehentie 2, P.O. Box 15400, 00076 Aalto, Finland
| | - Egon L Willighagen
- Institute of Environmental Medicine, Karolinska Institutet, Nobels väg 13, Box 210, SE-17177 Stockholm, Sweden.,Department of Bioinformatics-BiGCaT, Maastricht University, Universiteitssingel 50, P.O. Box 616, UNS 50 Box19, NL-6200 MD Maastricht, The Netherlands
| | - Rebecca Ceder
- Institute of Environmental Medicine, Karolinska Institutet, Nobels väg 13, Box 210, SE-17177 Stockholm, Sweden
| | - Krister Wennerberg
- Institute for Molecular Medicine Finland, FIMM, University of Helsinki, Tukholmankatu 8, P.O. Box 20, FI-00014 Helsinki, Finland
| | - Samuel Kaski
- Helsinki Institute for Information Technology HIIT, Department of Computer Science, Aalto University, Konemiehentie 2, P.O. Box 15400, 00076 Aalto, Finland.,Helsinki Institute for Information Technology HIIT, Department of Computer Science, University of Helsinki, Gustaf Hällströmin katu 2b, P.O. Box 68, FI-00014 Helsinki, Finland
| | - Roland C Grafström
- Institute of Environmental Medicine, Karolinska Institutet, Nobels väg 13, Box 210, SE-17177 Stockholm, Sweden
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Boyes WK, Thornton BLM, Al-Abed SR, Andersen CP, Bouchard DC, Burgess RM, Hubal EAC, Ho KT, Hughes MF, Kitchin K, Reichman JR, Rogers KR, Ross JA, Rygiewicz PT, Scheckel KG, Thai SF, Zepp RG, Zucker RM. A comprehensive framework for evaluating the environmental health and safety implications of engineered nanomaterials. Crit Rev Toxicol 2017; 47:767-810. [DOI: 10.1080/10408444.2017.1328400] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- William K. Boyes
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Brittany Lila M. Thornton
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Souhail R. Al-Abed
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH, USA
| | - Christian P. Andersen
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Corvallis, OR, USA
| | - Dermont C. Bouchard
- National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Athens, GA, USA
| | - Robert M. Burgess
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Narragansett, RI, USA
| | - Elaine A. Cohen Hubal
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Kay T. Ho
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Narragansett, RI, USA
| | - Michael F. Hughes
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Kirk Kitchin
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Jay R. Reichman
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Corvallis, OR, USA
| | - Kim R. Rogers
- National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Jeffrey A. Ross
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Paul T. Rygiewicz
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Corvallis, OR, USA
| | - Kirk G. Scheckel
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH, USA
| | - Sheau-Fung Thai
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Richard G. Zepp
- National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Athens, GA, USA
| | - Robert M. Zucker
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
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Dearfield KL, Gollapudi BB, Bemis JC, Benz RD, Douglas GR, Elespuru RK, Johnson GE, Kirkland DJ, LeBaron MJ, Li AP, Marchetti F, Pottenger LH, Rorije E, Tanir JY, Thybaud V, van Benthem J, Yauk CL, Zeiger E, Luijten M. Next generation testing strategy for assessment of genomic damage: A conceptual framework and considerations. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2017; 58:264-283. [PMID: 27650663 DOI: 10.1002/em.22045] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 08/08/2016] [Indexed: 06/06/2023]
Abstract
For several decades, regulatory testing schemes for genetic damage have been standardized where the tests being utilized examined mutations and structural and numerical chromosomal damage. This has served the genetic toxicity community well when most of the substances being tested were amenable to such assays. The outcome from this testing is usually a dichotomous (yes/no) evaluation of test results, and in many instances, the information is only used to determine whether a substance has carcinogenic potential or not. Over the same time period, mechanisms and modes of action (MOAs) that elucidate a wider range of genomic damage involved in many adverse health outcomes have been recognized. In addition, a paradigm shift in applied genetic toxicology is moving the field toward a more quantitative dose-response analysis and point-of-departure (PoD) determination with a focus on risks to exposed humans. This is directing emphasis on genomic damage that is likely to induce changes associated with a variety of adverse health outcomes. This paradigm shift is moving the testing emphasis for genetic damage from a hazard identification only evaluation to a more comprehensive risk assessment approach that provides more insightful information for decision makers regarding the potential risk of genetic damage to exposed humans. To enable this broader context for examining genetic damage, a next generation testing strategy needs to take into account a broader, more flexible approach to testing, and ultimately modeling, of genomic damage as it relates to human exposure. This is consistent with the larger risk assessment context being used in regulatory decision making. As presented here, this flexible approach for examining genomic damage focuses on testing for relevant genomic effects that can be, as best as possible, associated with an adverse health effect. The most desired linkage for risk to humans would be changes in loci associated with human diseases, whether in somatic or germ cells. The outline of a flexible approach and associated considerations are presented in a series of nine steps, some of which can occur in parallel, which was developed through a collaborative effort by leading genetic toxicologists from academia, government, and industry through the International Life Sciences Institute (ILSI) Health and Environmental Sciences Institute (HESI) Genetic Toxicology Technical Committee (GTTC). The ultimate goal is to provide quantitative data to model the potential risk levels of substances, which induce genomic damage contributing to human adverse health outcomes. Any good risk assessment begins with asking the appropriate risk management questions in a planning and scoping effort. This step sets up the problem to be addressed (e.g., broadly, does genomic damage need to be addressed, and if so, how to proceed). The next two steps assemble what is known about the problem by building a knowledge base about the substance of concern and developing a rational biological argument for why testing for genomic damage is needed or not. By focusing on the risk management problem and potential genomic damage of concern, the next step of assay(s) selection takes place. The work-up of the problem during the earlier steps provides the insight to which assays would most likely produce the most meaningful data. This discussion does not detail the wide range of genomic damage tests available, but points to types of testing systems that can be very useful. Once the assays are performed and analyzed, the relevant data sets are selected for modeling potential risk. From this point on, the data are evaluated and modeled as they are for any other toxicology endpoint. Any observed genomic damage/effects (or genetic event(s)) can be modeled via a dose-response analysis and determination of an estimated PoD. When a quantitative risk analysis is needed for decision making, a parallel exposure assessment effort is performed (exposure assessment is not detailed here as this is not the focus of this discussion; guidelines for this assessment exist elsewhere). Then the PoD for genomic damage is used with the exposure information to develop risk estimations (e.g., using reference dose (RfD), margin of exposure (MOE) approaches) in a risk characterization and presented to risk managers for informing decision making. This approach is applicable now for incorporating genomic damage results into the decision-making process for assessing potential adverse outcomes in chemically exposed humans and is consistent with the ILSI HESI Risk Assessment in the 21st Century (RISK21) roadmap. This applies to any substance to which humans are exposed, including pharmaceuticals, agricultural products, food additives, and other chemicals. It is time for regulatory bodies to incorporate the broader knowledge and insights provided by genomic damage results into the assessments of risk to more fully understand the potential of adverse outcomes in chemically exposed humans, thus improving the assessment of risk due to genomic damage. The historical use of genomic damage data as a yes/no gateway for possible cancer risk has been too narrowly focused in risk assessment. The recent advances in assaying for and understanding genomic damage, including eventually epigenetic alterations, obviously add a greater wealth of information for determining potential risk to humans. Regulatory bodies need to embrace this paradigm shift from hazard identification to quantitative analysis and to incorporate the wider range of genomic damage in their assessments of risk to humans. The quantitative analyses and methodologies discussed here can be readily applied to genomic damage testing results now. Indeed, with the passage of the recent update to the Toxic Substances Control Act (TSCA) in the US, the new generation testing strategy for genomic damage described here provides a regulatory agency (here the US Environmental Protection Agency (EPA), but suitable for others) a golden opportunity to reexamine the way it addresses risk-based genomic damage testing (including hazard identification and exposure). Environ. Mol. Mutagen. 58:264-283, 2017. © 2016 The Authors. Environmental and Molecular Mutagenesis Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Kerry L Dearfield
- U.S. Department of Agriculture, Food Safety and Inspection Service, Washington, District of Columbia
| | - B Bhaskar Gollapudi
- Exponent® Inc, Center for Toxicology and Mechanistic Biology, Midland, Michigan
| | | | | | - George R Douglas
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, K1A 0K9, Canada
| | - Rosalie K Elespuru
- U.S. Food and Drug Administration, CDRH/OSEL DBCMS, Silver Spring, Maryland
| | - George E Johnson
- Institute of Life Science, College of Medicine, Swansea University, Swansea, SA2 8PP, United Kingdom
| | | | - Matthew J LeBaron
- The Dow Chemical Company, Molecular, Cellular, and Biochemical Toxicology, Midland, Michigan
| | - Albert P Li
- In Vitro ADMET Laboratories LLC, Columbia, Maryland
| | - Francesco Marchetti
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, K1A 0K9, Canada
| | - Lynn H Pottenger
- Formerly of The Dow Chemical Company, Toxicology & Environmental Research and Consulting now with Olin Corporation, Midland, Michigan
| | - Emiel Rorije
- National Institute for Public Health and the Environment (RIVM), Center for Safety of Substances and Products, Bilthoven, 3720 BA, The Netherlands
| | - Jennifer Y Tanir
- ILSI Health and Environmental Sciences Institute (HESI), Washington, District of Columbia
| | - Veronique Thybaud
- Sanofi, Drug Disposition, Safety and Animal Research, Vitry-sur-Seine, France
| | - Jan van Benthem
- National Institute for Public Health and the Environment (RIVM), Center for Health Protection, Bilthoven, 3720 BA, The Netherlands
| | - Carole L Yauk
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, K1A 0K9, Canada
| | - Errol Zeiger
- Errol Zeiger Consulting, Chapel Hill, North Carolina
| | - Mirjam Luijten
- National Institute for Public Health and the Environment (RIVM), Center for Health Protection, Bilthoven, 3720 BA, The Netherlands
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Gobas FAPC, Otton SV, Tupper-Ring LF, Crawford MA, Clark KE, Ikonomou MG. Chemical activity-based environmental risk analysis of the plasticizer di-ethylhexyl phthalate and its main metabolite mono-ethylhexyl phthalate. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2017; 36:1483-1492. [PMID: 27859543 DOI: 10.1002/etc.3689] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 09/30/2016] [Accepted: 11/14/2016] [Indexed: 06/06/2023]
Abstract
The present study applies a chemical activity-based approach to: 1) evaluate environmental concentrations of di-ethylhexyl phthalate (DEHP; n = 23 651) and its metabolite mono-ethylhexyl phthalate (MEHP; n = 1232) in 16 environmental media from 1174 studies in the United States, Canada, Europe, and Asia, and in vivo toxicity data from 934 studies in 20 species, as well as in vitro biological activity data from the US Environmental Protection Agency's Toxicity Forecaster and other sources; and 2) conduct a comprehensive environmental risk analysis. The results show that the mean chemical activities of DEHP and MEHP in abiotic environmental samples from locations around the globe are 0.001 and 10-8 , respectively. This indicates that DEHP has reached on average 0.1% of saturation in the abiotic environment. The mean chemical activity of DEHP in biological samples is on average 100-fold lower than that in abiotic samples, likely because of biotransformation of DEHP in biota. Biological responses in both in vivo and in vitro tests occur at chemical activities between 0.01 to 1 for DEHP and between approximately 10-6 and 10-2 for MEHP, suggesting a greater potency of MEHP compared with DEHP. Chemical activities of both DEHP and MEHP in biota samples were less than those causing biological responses in the in vitro bioassays, without exception. A small fraction of chemical activities of DEHP in abiotic environmental samples (i.e., 4-8%) and none (0%) for MEHP were within the range of chemical activities associated with observed toxicological responses in the in vivo tests. The present study illustrates the chemical activity approach for conducting risk analyses. Environ Toxicol Chem 2017;36:1483-1492. © 2016 SETAC.
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Affiliation(s)
- Frank A P C Gobas
- School of Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia, Canada
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - S Victoria Otton
- School of Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Laura F Tupper-Ring
- School of Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Meara A Crawford
- School of Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia, Canada
| | | | - Michael G Ikonomou
- Institute of Ocean Sciences, Ocean Sciences Division, Fisheries and Oceans Canada, Sidney, British Columbia, Canada
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119
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Bus JS. IARC use of oxidative stress as key mode of action characteristic for facilitating cancer classification: Glyphosate case example illustrating a lack of robustness in interpretative implementation. Regul Toxicol Pharmacol 2017; 86:157-166. [PMID: 28274811 DOI: 10.1016/j.yrtph.2017.03.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 02/28/2017] [Accepted: 03/02/2017] [Indexed: 11/27/2022]
Abstract
The International Agency for Research on Cancer (IARC) has formulated 10 key characteristics of human carcinogens to incorporate mechanistic data into cancer hazard classifications. The analysis used glyphosate as a case example to examine the robustness of IARC's determination of oxidative stress as "strong" evidence supporting a plausible cancer mechanism in humans. The IARC analysis primarily relied on 14 human/mammalian studies; 19 non-mammalian studies were uninformative of human cancer given the broad spectrum of test species and extensive use of formulations and aquatic testing. The mammalian studies had substantial experimental limitations for informing cancer mechanism including use of: single doses and time points; cytotoxic/toxic test doses; tissues not identified as potential cancer targets; glyphosate formulations or mixtures; technically limited oxidative stress biomarkers. The doses were many orders of magnitude higher than human exposures determined in human biomonitoring studies. The glyphosate case example reveals that the IARC evaluation fell substantially short of "strong" supporting evidence of oxidative stress as a plausible human cancer mechanism, and suggests that other IARC monographs relying on the 10 key characteristics approach should be similarly examined for a lack of robust data integration fundamental to reasonable mode of action evaluations.
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Affiliation(s)
- James S Bus
- Exponent, Inc., 1800 Diagonal Road, Suite 500, Alexandria, VA 22314, United States.
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120
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“The dose makes the poison”: Key implications for mode of action (mechanistic) research in a 21st century toxicology paradigm. CURRENT OPINION IN TOXICOLOGY 2017. [DOI: 10.1016/j.cotox.2017.06.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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121
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Rees BJ, Tate M, Lynch AM, Thornton CA, Jenkins GJ, Walmsley RM, Johnson GE. Development of an in vitro PIG-A gene mutation assay in human cells. Mutagenesis 2017; 32:283-297. [PMID: 28057708 PMCID: PMC5907909 DOI: 10.1093/mutage/gew059] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 11/15/2016] [Indexed: 11/12/2022] Open
Abstract
Mutagens can be carcinogens, and traditionally, they have been identified in vitro using the Salmonella 'Ames' reverse mutation assay. However, prokaryotic DNA packaging, replication and repair systems are mechanistically very different to those in the humans we inevitably seek to protect. Therefore, for many years, mammalian cell line genotoxicity assays that can detect eukaryotic mutagens as well as clastogens and aneugens have been used. The apparent lack of specificity in these largely rodent systems, due partly to their mutant p53 status, has contributed to the use of animal studies to resolve data conflicts. Recently, silencing mutations at the PIG-A locus have been demonstrated to prevent glycophosphatidylinositol (GPI) anchor synthesis and consequentially result in loss of GPI-anchored proteins from the cell's extracellular surface. The successful exploitation of this mutant phenotype in animal studies has triggered interest in the development of an analogous in vitro PIG-A mutation screening assay. This article describes the development of a robust assay design using metabolically active human cells. The assay includes viability and cell membrane integrity assessment and conforms to the future ideas of the 21st-century toxicology testing.
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Affiliation(s)
- Benjamin J Rees
- Institute of Life Science, Swansea University Medical School, Singleton Park, Swansea, UK
| | - Matthew Tate
- Gentronix Ltd BioHub at Alderley Park, Alderley Edge, Cheshire, UK
| | | | - Catherine A Thornton
- Institute of Life Science, Swansea University Medical School, Singleton Park, Swansea, UK
| | - Gareth J Jenkins
- Institute of Life Science, Swansea University Medical School, Singleton Park, Swansea, UK
| | - Richard M Walmsley
- Gentronix Ltd BioHub at Alderley Park, Alderley Edge, Cheshire, UK
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - George E Johnson
- Institute of Life Science, Swansea University Medical School, Singleton Park, Swansea, UK
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Sirenko O, Grimm FA, Ryan KR, Iwata Y, Chiu WA, Parham F, Wignall JA, Anson B, Cromwell EF, Behl M, Rusyn I, Tice RR. In vitro cardiotoxicity assessment of environmental chemicals using an organotypic human induced pluripotent stem cell-derived model. Toxicol Appl Pharmacol 2017; 322:60-74. [PMID: 28259702 DOI: 10.1016/j.taap.2017.02.020] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 01/24/2017] [Accepted: 02/27/2017] [Indexed: 01/22/2023]
Abstract
An important target area for addressing data gaps through in vitro screening is the detection of potential cardiotoxicants. Despite the fact that current conservative estimates relate at least 23% of all cardiovascular disease cases to environmental exposures, the identities of the causative agents remain largely uncharacterized. Here, we evaluate the feasibility of a combinatorial in vitro/in silico screening approach for functional and mechanistic cardiotoxicity profiling of environmental hazards using a library of 69 representative environmental chemicals and drugs. Human induced pluripotent stem cell-derived cardiomyocytes were exposed in concentration-response for 30min or 24h and effects on cardiomyocyte beating and cellular and mitochondrial toxicity were assessed by kinetic measurements of intracellular Ca2+ flux and high-content imaging using the nuclear dye Hoechst 33342, the cell viability marker Calcein AM, and the mitochondrial depolarization probe JC-10. More than half of the tested chemicals exhibited effects on cardiomyocyte beating after 30min of exposure. In contrast, after 24h, effects on cell beating without concomitant cytotoxicity were observed in about one third of the compounds. Concentration-response data for in vitro bioactivity phenotypes visualized using the Toxicological Prioritization Index (ToxPi) showed chemical class-specific clustering of environmental chemicals, including pesticides, flame retardants, and polycyclic aromatic hydrocarbons. For environmental chemicals with human exposure predictions, the activity-to-exposure ratios between modeled blood concentrations and in vitro bioactivity were between one and five orders of magnitude. These findings not only demonstrate that some ubiquitous environmental pollutants might have the potential at high exposure levels to alter cardiomyocyte function, but also indicate similarities in the mechanism of these effects both within and among chemicals and classes.
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Affiliation(s)
| | - Fabian A Grimm
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Kristen R Ryan
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - Yasuhiro Iwata
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Weihsueh A Chiu
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Frederick Parham
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | | | - Blake Anson
- Cellular Dynamics International, Madison, WI, USA
| | | | - Mamta Behl
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Raymond R Tice
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
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Kleinstreuer NC, Ceger P, Watt ED, Martin M, Houck K, Browne P, Thomas RS, Casey WM, Dix DJ, Allen D, Sakamuru S, Xia M, Huang R, Judson R. Development and Validation of a Computational Model for Androgen Receptor Activity. Chem Res Toxicol 2016; 30:946-964. [PMID: 27933809 PMCID: PMC5396026 DOI: 10.1021/acs.chemrestox.6b00347] [Citation(s) in RCA: 144] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Testing thousands of chemicals to identify potential androgen receptor (AR) agonists or antagonists would cost millions of dollars and take decades to complete using current validated methods. High-throughput in vitro screening (HTS) and computational toxicology approaches can more rapidly and inexpensively identify potential androgen-active chemicals. We integrated 11 HTS ToxCast/Tox21 in vitro assays into a computational network model to distinguish true AR pathway activity from technology-specific assay interference. The in vitro HTS assays probed perturbations of the AR pathway at multiple points (receptor binding, coregulator recruitment, gene transcription, and protein production) and multiple cell types. Confirmatory in vitro antagonist assay data and cytotoxicity information were used as additional flags for potential nonspecific activity. Validating such alternative testing strategies requires high-quality reference data. We compiled 158 putative androgen-active and -inactive chemicals from a combination of international test method validation efforts and semiautomated systematic literature reviews. Detailed in vitro assay information and results were compiled into a single database using a standardized ontology. Reference chemical concentrations that activated or inhibited AR pathway activity were identified to establish a range of potencies with reproducible reference chemical results. Comparison with existing Tier 1 AR binding data from the U.S. EPA Endocrine Disruptor Screening Program revealed that the model identified binders at relevant test concentrations (<100 μM) and was more sensitive to antagonist activity. The AR pathway model based on the ToxCast/Tox21 assays had balanced accuracies of 95.2% for agonist (n = 29) and 97.5% for antagonist (n = 28) reference chemicals. Out of 1855 chemicals screened in the AR pathway model, 220 chemicals demonstrated AR agonist or antagonist activity and an additional 174 chemicals were predicted to have potential weak AR pathway activity.
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Affiliation(s)
- Nicole C Kleinstreuer
- NIH/NIEHS/DNTP/The NTP Interagency Center for the Evaluation of Alternative Toxicological Methods , Research Triangle Park, North Carolina 27713, United States
| | - Patricia Ceger
- Integrated Laboratory Systems, Inc. , Research Triangle Park, North Carolina 27560, United States
| | - Eric D Watt
- EPA/ORD/National Center for Computational Toxicology , Research Triangle Park, North Carolina 27711, United States
| | - Matthew Martin
- EPA/ORD/National Center for Computational Toxicology , Research Triangle Park, North Carolina 27711, United States
| | - Keith Houck
- EPA/ORD/National Center for Computational Toxicology , Research Triangle Park, North Carolina 27711, United States
| | - Patience Browne
- OECD Environment Directorate, Environment Health and Safety Division , Paris 75775, France
| | - Russell S Thomas
- EPA/ORD/National Center for Computational Toxicology , Research Triangle Park, North Carolina 27711, United States
| | - Warren M Casey
- NIH/NIEHS/DNTP/The NTP Interagency Center for the Evaluation of Alternative Toxicological Methods , Research Triangle Park, North Carolina 27713, United States
| | - David J Dix
- EPA/OCSPP/Office of Science Coordination and Policy , Washington, DC, 20460, United States
| | - David Allen
- Integrated Laboratory Systems, Inc. , Research Triangle Park, North Carolina 27560, United States
| | - Srilatha Sakamuru
- NIH/National Center for Advancing Translational Sciences , Bethesda, Maryland 20892, United States
| | - Menghang Xia
- NIH/National Center for Advancing Translational Sciences , Bethesda, Maryland 20892, United States
| | - Ruili Huang
- NIH/National Center for Advancing Translational Sciences , Bethesda, Maryland 20892, United States
| | - Richard Judson
- EPA/ORD/National Center for Computational Toxicology , Research Triangle Park, North Carolina 27711, United States
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Farmahin R, Williams A, Kuo B, Chepelev NL, Thomas RS, Barton-Maclaren TS, Curran IH, Nong A, Wade MG, Yauk CL. Recommended approaches in the application of toxicogenomics to derive points of departure for chemical risk assessment. Arch Toxicol 2016; 91:2045-2065. [PMID: 27928627 PMCID: PMC5399047 DOI: 10.1007/s00204-016-1886-5] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 11/02/2016] [Indexed: 12/15/2022]
Abstract
There is increasing interest in the use of quantitative transcriptomic data to determine benchmark dose (BMD) and estimate a point of departure (POD) for human health risk assessment. Although studies have shown that transcriptional PODs correlate with those derived from apical endpoint changes, there is no consensus on the process used to derive a transcriptional POD. Specifically, the subsets of informative genes that produce BMDs that best approximate the doses at which adverse apical effects occur have not been defined. To determine the best way to select predictive groups of genes, we used published microarray data from dose–response studies on six chemicals in rats exposed orally for 5, 14, 28, and 90 days. We evaluated eight approaches for selecting genes for POD derivation and three previously proposed approaches (the lowest pathway BMD, and the mean and median BMD of all genes). The relationship between transcriptional BMDs derived using these 11 approaches and PODs derived from apical data that might be used in chemical risk assessment was examined. Transcriptional BMD values for all 11 approaches were remarkably aligned with corresponding apical PODs, with the vast majority of toxicogenomics PODs being within tenfold of those derived from apical endpoints. We identified at least four approaches that produce BMDs that are effective estimates of apical PODs across multiple sampling time points. Our results support that a variety of approaches can be used to derive reproducible transcriptional PODs that are consistent with PODs produced from traditional methods for chemical risk assessment.
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Affiliation(s)
- Reza Farmahin
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, K1A 0K9, Canada
| | - Andrew Williams
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, K1A 0K9, Canada
| | - Byron Kuo
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, K1A 0K9, Canada
| | - Nikolai L Chepelev
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, K1A 0K9, Canada
| | - Russell S Thomas
- National Center for Computational Toxicology, United States Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Tara S Barton-Maclaren
- Existing Substances Risk Assessment Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, K1A 0K9, Canada
| | - Ivan H Curran
- Toxicology Research Division, Health Products and Food Branch, Health Canada, Ottawa, ON, K1A 0K9, Canada
| | - Andy Nong
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, K1A 0K9, Canada
| | - Michael G Wade
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, K1A 0K9, Canada
| | - Carole L Yauk
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, K1A 0K9, Canada.
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Louisse J, Beekmann K, Rietjens IMCM. Use of Physiologically Based Kinetic Modeling-Based Reverse Dosimetry to Predict in Vivo Toxicity from in Vitro Data. Chem Res Toxicol 2016; 30:114-125. [PMID: 27768849 DOI: 10.1021/acs.chemrestox.6b00302] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The development of reliable nonanimal based testing strategies, such as in vitro bioassays, is the holy grail in current human safety testing of chemicals. However, the use of in vitro toxicity data in risk assessment is not straightforward. One of the main issues is that concentration-response curves from in vitro models need to be converted to in vivo dose-response curves. These dose-response curves are needed in toxicological risk assessment to obtain a point of departure to determine safe exposure levels for humans. Recent scientific developments enable this translation of in vitro concentration-response curves to in vivo dose-response curves using physiologically based kinetic (PBK) modeling-based reverse dosimetry. The present review provides an overview of the examples available in the literature on the prediction of in vivo toxicity using PBK modeling-based reverse dosimetry of in vitro toxicity data, showing that proofs-of-principle are available for toxicity end points ranging from developmental toxicity, nephrotoxicity, hepatotoxicity, and neurotoxicity to DNA adduct formation. This review also discusses the promises and pitfalls, and the future perspectives of the approach. Since proofs-of-principle available so far have been provided for the prediction of toxicity in experimental animals, future research should focus on the use of in vitro toxicity data obtained in human models to predict the human situation using human PBK models. This would facilitate human- instead of experimental animal-based approaches in risk assessment.
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Affiliation(s)
- Jochem Louisse
- Division of Toxicology, Wageningen University , Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Karsten Beekmann
- Division of Toxicology, Wageningen University , Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Ivonne M C M Rietjens
- Division of Toxicology, Wageningen University , Stippeneng 4, 6708 WE Wageningen, The Netherlands
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126
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Cote I, Andersen ME, Ankley GT, Barone S, Birnbaum LS, Boekelheide K, Bois FY, Burgoon LD, Chiu WA, Crawford-Brown D, Crofton KM, DeVito M, Devlin RB, Edwards SW, Guyton KZ, Hattis D, Judson RS, Knight D, Krewski D, Lambert J, Maull EA, Mendrick D, Paoli GM, Patel CJ, Perkins EJ, Poje G, Portier CJ, Rusyn I, Schulte PA, Simeonov A, Smith MT, Thayer KA, Thomas RS, Thomas R, Tice RR, Vandenberg JJ, Villeneuve DL, Wesselkamper S, Whelan M, Whittaker C, White R, Xia M, Yauk C, Zeise L, Zhao J, DeWoskin RS. The Next Generation of Risk Assessment Multi-Year Study-Highlights of Findings, Applications to Risk Assessment, and Future Directions. ENVIRONMENTAL HEALTH PERSPECTIVES 2016; 124:1671-1682. [PMID: 27091369 PMCID: PMC5089888 DOI: 10.1289/ehp233] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 10/30/2015] [Accepted: 03/29/2016] [Indexed: 05/19/2023]
Abstract
BACKGROUND The Next Generation (NexGen) of Risk Assessment effort is a multi-year collaboration among several organizations evaluating new, potentially more efficient molecular, computational, and systems biology approaches to risk assessment. This article summarizes our findings, suggests applications to risk assessment, and identifies strategic research directions. OBJECTIVE Our specific objectives were to test whether advanced biological data and methods could better inform our understanding of public health risks posed by environmental exposures. METHODS New data and methods were applied and evaluated for use in hazard identification and dose-response assessment. Biomarkers of exposure and effect, and risk characterization were also examined. Consideration was given to various decision contexts with increasing regulatory and public health impacts. Data types included transcriptomics, genomics, and proteomics. Methods included molecular epidemiology and clinical studies, bioinformatic knowledge mining, pathway and network analyses, short-duration in vivo and in vitro bioassays, and quantitative structure activity relationship modeling. DISCUSSION NexGen has advanced our ability to apply new science by more rapidly identifying chemicals and exposures of potential concern, helping characterize mechanisms of action that influence conclusions about causality, exposure-response relationships, susceptibility and cumulative risk, and by elucidating new biomarkers of exposure and effects. Additionally, NexGen has fostered extensive discussion among risk scientists and managers and improved confidence in interpreting and applying new data streams. CONCLUSIONS While considerable uncertainties remain, thoughtful application of new knowledge to risk assessment appears reasonable for augmenting major scope assessments, forming the basis for or augmenting limited scope assessments, and for prioritization and screening of very data limited chemicals. Citation: Cote I, Andersen ME, Ankley GT, Barone S, Birnbaum LS, Boekelheide K, Bois FY, Burgoon LD, Chiu WA, Crawford-Brown D, Crofton KM, DeVito M, Devlin RB, Edwards SW, Guyton KZ, Hattis D, Judson RS, Knight D, Krewski D, Lambert J, Maull EA, Mendrick D, Paoli GM, Patel CJ, Perkins EJ, Poje G, Portier CJ, Rusyn I, Schulte PA, Simeonov A, Smith MT, Thayer KA, Thomas RS, Thomas R, Tice RR, Vandenberg JJ, Villeneuve DL, Wesselkamper S, Whelan M, Whittaker C, White R, Xia M, Yauk C, Zeise L, Zhao J, DeWoskin RS. 2016. The Next Generation of Risk Assessment multiyear study-highlights of findings, applications to risk assessment, and future directions. Environ Health Perspect 124:1671-1682; http://dx.doi.org/10.1289/EHP233.
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Affiliation(s)
- Ila Cote
- National Center for Environmental Assessment, U.S. Environmental Protection Agency (EPA), Washington, District of Columbia, USA
- Address correspondence to I. Cote, U.S. Environmental Protection Agency, Region 8, Room 8152, 1595 Wynkoop St., Denver, CO 80202-1129 USA. Telephone: (202) 288-9539. E-mail:
| | | | - Gerald T. Ankley
- National Health and Environmental Effects Research Laboratory, U.S. EPA, Duluth, Minnesota, USA
| | - Stanley Barone
- Office of Chemical Safety and Pollution Prevention, U.S. EPA, Washington, District of Columbia, USA
| | - Linda S. Birnbaum
- National Institute of Environmental Health Sciences, and
- National Toxicology Program, National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | - Kim Boekelheide
- Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island, USA
| | - Frederic Y. Bois
- Unité Modèles pour l’Écotoxicologie et la Toxicologie, Institut National de l’Environnement Industriel et des Risques, Verneuil en Halatte, France
| | - Lyle D. Burgoon
- U.S. Army Engineer Research and Development Center, Research Triangle Park, North Carolina, USA
| | - Weihsueh A. Chiu
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | | | | | - Michael DeVito
- National Institute of Environmental Health Sciences, and
- National Toxicology Program, National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | - Robert B. Devlin
- National Health and Environmental Effects Research Laboratory, U.S. EPA, Research Triangle Park, North Carolina, USA
| | - Stephen W. Edwards
- National Health and Environmental Effects Research Laboratory, U.S. EPA, Research Triangle Park, North Carolina, USA
| | | | - Dale Hattis
- George Perkins Marsh Institute, Clark University, Worcester, Massachusetts, USA
| | | | - Derek Knight
- European Chemicals Agency, Annankatu, Helsinki, Finland
| | - Daniel Krewski
- McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa, Ontario, Canada
| | - Jason Lambert
- National Center for Environmental Assessment, U.S. EPA, Cincinnati, Ohio, USA
| | - Elizabeth Anne Maull
- National Institute of Environmental Health Sciences, and
- National Toxicology Program, National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | - Donna Mendrick
- National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas, USA
| | | | - Chirag Jagdish Patel
- Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts, USA
| | - Edward J. Perkins
- U.S. Army Engineer Research and Development Center, Vicksburg, Mississippi, USA
| | - Gerald Poje
- Grant Consulting Group, Washington, District of Columbia, USA
| | | | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Paul A. Schulte
- Education and Information Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, Ohio, USA
| | - Anton Simeonov
- National Center for Advancing Translational Sciences, NIH, DHHS, Bethesda, Maryland, USA
| | - Martyn T. Smith
- Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, Berkeley, California, USA
| | - Kristina A. Thayer
- National Institute of Environmental Health Sciences, and
- National Toxicology Program, National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | | | - Reuben Thomas
- Gladstone Institutes, University of California, San Francisco, San Francisco, California, USA
| | - Raymond R. Tice
- National Institute of Environmental Health Sciences, and
- National Toxicology Program, National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | - John J. Vandenberg
- National Center for Environmental Assessment, U.S. Environmental Protection Agency (EPA), Washington, District of Columbia, USA
| | - Daniel L. Villeneuve
- National Health and Environmental Effects Research Laboratory, U.S. EPA, Duluth, Minnesota, USA
| | - Scott Wesselkamper
- National Center for Environmental Assessment, U.S. EPA, Cincinnati, Ohio, USA
| | - Maurice Whelan
- Systems Toxicology Unit, European Commission Joint Research Centre, Ispra, Italy
| | - Christine Whittaker
- Education and Information Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, Ohio, USA
| | - Ronald White
- Center for Effective Government, Washington, District of Columbia, USA
| | - Menghang Xia
- National Center for Advancing Translational Sciences, NIH, DHHS, Bethesda, Maryland, USA
| | - Carole Yauk
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - Lauren Zeise
- Office of Environmental Health Hazard Assessment, California EPA, Oakland, California, USA
| | - Jay Zhao
- National Center for Environmental Assessment, U.S. EPA, Cincinnati, Ohio, USA
| | - Robert S. DeWoskin
- National Center for Environmental Assessment, U.S. Environmental Protection Agency (EPA), Washington, District of Columbia, USA
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Csiszar SA, Meyer DE, Dionisio KL, Egeghy P, Isaacs KK, Price PS, Scanlon KA, Tan YM, Thomas K, Vallero D, Bare JC. Conceptual Framework To Extend Life Cycle Assessment Using Near-Field Human Exposure Modeling and High-Throughput Tools for Chemicals. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:11922-11934. [PMID: 27668689 PMCID: PMC7388028 DOI: 10.1021/acs.est.6b02277] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Life Cycle Assessment (LCA) is a decision-making tool that accounts for multiple impacts across the life cycle of a product or service. This paper presents a conceptual framework to integrate human health impact assessment with risk screening approaches to extend LCA to include near-field chemical sources (e.g., those originating from consumer products and building materials) that have traditionally been excluded from LCA. A new generation of rapid human exposure modeling and high-throughput toxicity testing is transforming chemical risk prioritization and provides an opportunity for integration of screening-level risk assessment (RA) with LCA. The combined LCA and RA approach considers environmental impacts of products alongside risks to human health, which is consistent with regulatory frameworks addressing RA within a sustainability mindset. A case study is presented to juxtapose LCA and risk screening approaches for a chemical used in a consumer product. The case study demonstrates how these new risk screening tools can be used to inform toxicity impact estimates in LCA and highlights needs for future research. The framework provides a basis for developing tools and methods to support decision making on the use of chemicals in products.
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Affiliation(s)
- Susan A Csiszar
- Oak Ridge Institute for Science and Education (ORISE) Research Participation Program, hosted at U.S. Environmental Protection Agency , Cincinnati, Ohio 45268, United States
| | - David E Meyer
- Office of Research and Development, National Risk Management Research Laboratory, U.S. Environmental Protection Agency , Cincinnati, Ohio 45268, United States
| | - Kathie L Dionisio
- Office of Research and Development, National Exposure Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park, North Carolina 27711, United States
| | - Peter Egeghy
- Office of Research and Development, National Exposure Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park, North Carolina 27711, United States
| | - Kristin K Isaacs
- Office of Research and Development, National Exposure Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park, North Carolina 27711, United States
| | - Paul S Price
- Office of Research and Development, National Exposure Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park, North Carolina 27711, United States
| | - Kelly A Scanlon
- AAAS Science & Technology Policy Fellow hosted by the U.S. Environmental Protection Agency, Office of Air and Radiation, Office of Radiation and Indoor Air, Washington, DC 20460, United States
| | - Yu-Mei Tan
- Office of Research and Development, National Exposure Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park, North Carolina 27711, United States
| | - Kent Thomas
- Office of Research and Development, National Exposure Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park, North Carolina 27711, United States
| | - Daniel Vallero
- Office of Research and Development, National Exposure Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park, North Carolina 27711, United States
| | - Jane C Bare
- Office of Research and Development, National Risk Management Research Laboratory, U.S. Environmental Protection Agency , Cincinnati, Ohio 45268, United States
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128
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Fischer BM, Neumann D, Piberger AL, Risnes SF, Köberle B, Hartwig A. Use of high-throughput RT-qPCR to assess modulations of gene expression profiles related to genomic stability and interactions by cadmium. Arch Toxicol 2016; 90:2745-2761. [PMID: 26525392 PMCID: PMC5065590 DOI: 10.1007/s00204-015-1621-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 10/20/2015] [Indexed: 01/21/2023]
Abstract
Predictive test systems to assess the mode of action of chemical carcinogens are urgently required. Within the present study, we applied the Fluidigm dynamic array on the BioMark™ HD System for quantitative high-throughput RT-qPCR analysis of 95 genes and 96 samples in parallel, selecting genes crucial for maintaining genomic stability, including stress response as well as DNA repair, cell cycle control, apoptosis and mitotic signaling. The specificity of each individually designed sequence-specific primer pair and their respective target amplicons were evaluated via melting curve analysis as part of qPCR and size verification via agarose gel electrophoresis. For each gene, calibration curves displayed high efficiencies and correlation coefficients in the identified linear dynamic range as well as low intra-assay variations. Data were processed via Fluidigm real-time PCR analysis and GenEx software, and results were depicted as relative gene expression according to the ΔΔC q method. Subsequently, gene expression analyses were conducted in cadmium-treated adenocarcinoma A549 and epithelial bronchial BEAS-2B cells. They revealed distinct dose- and time-dependent and also cell-type-specific gene expression patterns, including the induction of genes coding for metallothioneins, the oxidative stress response, cell cycle control, mitotic signaling and apoptosis. Interestingly, while genes coding for the DNA damage response were induced, distinct DNA repair genes were down-regulated at the transcriptional level. Thus, this approach provided a comprehensive overview on the interaction by cadmium with distinct signaling pathways, also reflecting molecular modes of action in cadmium-induced carcinogenicity. Therefore, the test system appears to be a promising tool for toxicological risk assessment.
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Affiliation(s)
- Bettina Maria Fischer
- Department of Food Chemistry and Toxicology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131, Karlsruhe, Germany
| | - Daniel Neumann
- Department of Food Chemistry and Toxicology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131, Karlsruhe, Germany
| | - Ann Liza Piberger
- Department of Food Chemistry and Toxicology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131, Karlsruhe, Germany
| | - Sarah Fremgaard Risnes
- Department of Food Chemistry and Toxicology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131, Karlsruhe, Germany
| | - Beate Köberle
- Department of Food Chemistry and Toxicology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131, Karlsruhe, Germany
| | - Andrea Hartwig
- Department of Food Chemistry and Toxicology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131, Karlsruhe, Germany.
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129
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Martin F, Talikka M, Hoeng J, Peitsch MC. Identification of gene expression signature for cigarette smoke exposure response--from man to mouse. Hum Exp Toxicol 2016; 34:1200-11. [PMID: 26614807 DOI: 10.1177/0960327115600364] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Gene expression profiling data can be used in toxicology to assess both the level and impact of toxicant exposure, aligned with a vision of 21st century toxicology. Here, we present a whole blood-derived gene signature that can distinguish current smokers from either nonsmokers or former smokers with high specificity and sensitivity. Such a signature that can be measured in a surrogate tissue (whole blood) may help in monitoring smoking exposure as well as discontinuation of exposure when the primarily impacted tissue (e.g., lung) is not readily accessible. The signature consisted of LRRN3, SASH1, PALLD, RGL1, TNFRSF17, CDKN1C, IGJ, RRM2, ID3, SERPING1, and FUCA1. Several members of this signature have been previously described in the context of smoking. The signature translated well across species and could distinguish mice that were exposed to cigarette smoke from ones exposed to air only or had been withdrawn from cigarette smoke exposure. Finally, the small signature of only 11 genes could be converted into a polymerase chain reaction-based assay that could serve as a marker to monitor compliance with a smoking abstinence protocol.
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Affiliation(s)
- F Martin
- Philip Morris International Research and Development, Neuchatel, Switzerland
| | - M Talikka
- Philip Morris International Research and Development, Neuchatel, Switzerland
| | - J Hoeng
- Philip Morris International Research and Development, Neuchatel, Switzerland
| | - M C Peitsch
- Philip Morris International Research and Development, Neuchatel, Switzerland
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130
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Pendse SN, Maertens A, Rosenberg M, Roy D, Fasani RA, Vantangoli MM, Madnick SJ, Boekelheide K, Fornace AJ, Odwin SA, Yager JD, Hartung T, Andersen ME, McMullen PD. Information-dependent enrichment analysis reveals time-dependent transcriptional regulation of the estrogen pathway of toxicity. Arch Toxicol 2016; 91:1749-1762. [PMID: 27592001 PMCID: PMC5364265 DOI: 10.1007/s00204-016-1824-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 08/22/2016] [Indexed: 02/06/2023]
Abstract
The twenty-first century vision for toxicology involves a transition away from high-dose animal studies to in vitro and computational models (NRC in Toxicity testing in the 21st century: a vision and a strategy, The National Academies Press, Washington, DC, 2007). This transition requires mapping pathways of toxicity by understanding how in vitro systems respond to chemical perturbation. Uncovering transcription factors/signaling networks responsible for gene expression patterns is essential for defining pathways of toxicity, and ultimately, for determining the chemical modes of action through which a toxicant acts. Traditionally, transcription factor identification is achieved via chromatin immunoprecipitation studies and summarized by calculating which transcription factors are statistically associated with up- and downregulated genes. These lists are commonly determined via statistical or fold-change cutoffs, a procedure that is sensitive to statistical power and may not be as useful for determining transcription factor associations. To move away from an arbitrary statistical or fold-change-based cutoff, we developed, in the context of the Mapping the Human Toxome project, an enrichment paradigm called information-dependent enrichment analysis (IDEA) to guide identification of the transcription factor network. We used a test case of activation in MCF-7 cells by 17β estradiol (E2). Using this new approach, we established a time course for transcriptional and functional responses to E2. ERα and ERβ were associated with short-term transcriptional changes in response to E2. Sustained exposure led to recruitment of additional transcription factors and alteration of cell cycle machinery. TFAP2C and SOX2 were the transcription factors most highly correlated with dose. E2F7, E2F1, and Foxm1, which are involved in cell proliferation, were enriched only at 24 h. IDEA should be useful for identifying candidate pathways of toxicity. IDEA outperforms gene set enrichment analysis (GSEA) and provides similar results to weighted gene correlation network analysis, a platform that helps to identify genes not annotated to pathways.
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Affiliation(s)
- Salil N Pendse
- The Hamner Institutes for Health Sciences, Research Triangle Park, NC, USA.,ScitoVation, LLC, 6 Davis Drive, PO Box 110566, Research Triangle Park, NC, 27709, USA
| | - Alexandra Maertens
- Center for Alternatives to Animal Testing (CAAT), Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | | | | | | | | | - Samantha J Madnick
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, USA
| | - Kim Boekelheide
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, USA
| | - Albert J Fornace
- Department of Biochemistry and Molecular and Cellular Biology, and Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
| | - Shelly-Ann Odwin
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - James D Yager
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Thomas Hartung
- Center for Alternatives to Animal Testing (CAAT), Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,Center for Alternatives to Animal Testing-Europe, University of Konstanz, Constance, Germany
| | - Melvin E Andersen
- The Hamner Institutes for Health Sciences, Research Triangle Park, NC, USA.,ScitoVation, LLC, 6 Davis Drive, PO Box 110566, Research Triangle Park, NC, 27709, USA
| | - Patrick D McMullen
- The Hamner Institutes for Health Sciences, Research Triangle Park, NC, USA. .,ScitoVation, LLC, 6 Davis Drive, PO Box 110566, Research Triangle Park, NC, 27709, USA.
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131
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Webster AF, Lambert IB, Yauk CL. Toxicogenomics Case Study: Furan. TOXICOGENOMICS IN PREDICTIVE CARCINOGENICITY 2016. [DOI: 10.1039/9781782624059-00390] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Development of pragmatic methodologies for human health risk assessment is required to address current regulatory challenges. We applied three toxicogenomic approaches—quantitative, predictive, and mechanistic—to a case study in mice exposed for 3 weeks to the hepatocarcinogen furan. We modeled the dose response of a variety of transcriptional endpoints and found that they produced benchmark doses similar to the furan-dependent cancer benchmark doses. Meta-analyses showed strong similarity between furan-dependent gene expression changes and those associated with several hepatic pathologies. Molecular pathways facilitated the development of a molecular mode of action for furan-induced hepatocellular carcinogenicity. Finally, we compared transcriptomic profiles derived from formalin-fixed and paraffin-embedded (FFPE) samples with those from high-quality frozen samples to evaluate whether archival samples are a viable option for toxicogenomic studies. The advantage of using FFPE tissues is that they are very well characterized (phenotypically); the disadvantage is that formalin degrades biomacromolecules, including RNA. We found that FFPE samples can be used for toxicogenomics using a ribo-depletion RNA-seq protocol. Our case study demonstrates the utility of toxicogenomics data to human health risk assessment, the potential of archival FFPE tissue samples, and identifies viable strategies toward the reduction of animal usage in chemical testing.
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Affiliation(s)
- A. Francina Webster
- Department of Biology, Carleton University 1125 Colonel By Drive Ottawa ON Canada
- Environmental Health Science and Research Bureau, Health Canada, Tunney's Pasture 50 Colombine Driveway Ottawa ON Canada
| | - Iain B. Lambert
- Department of Biology, Carleton University 1125 Colonel By Drive Ottawa ON Canada
| | - Carole L. Yauk
- Environmental Health Science and Research Bureau, Health Canada, Tunney's Pasture 50 Colombine Driveway Ottawa ON Canada
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Abstract
The exponential growth of the Internet of Things and the global popularity and remarkable decline in cost of the mobile phone is driving the digital transformation of medical practice. The rapidly maturing digital, non-medical world of mobile (wireless) devices, cloud computing and social networking is coalescing with the emerging digital medical world of omics data, biosensors and advanced imaging which offers the increasingly realistic prospect of personalized medicine. Described as a potential “seismic” shift from the current “healthcare” model to a “wellness” paradigm that is predictive, preventative, personalized and participatory, this change is based on the development of increasingly sophisticated biosensors which can track and measure key biochemical variables in people. Additional key drivers in this shift are metabolomic and proteomic signatures, which are increasingly being reported as pre-symptomatic, diagnostic and prognostic of toxicity and disease. These advancements also have profound implications for toxicological evaluation and safety assessment of pharmaceuticals and environmental chemicals. An approach based primarily on human in vivo and high-throughput in vitro human cell-line data is a distinct possibility. This would transform current chemical safety assessment practice which operates in a human “data poor” to a human “data rich” environment. This could also lead to a seismic shift from the current animal-based to an animal-free chemical safety assessment paradigm.
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Affiliation(s)
- George D Loizou
- Health Risks, Health and Safety Laboratory, Health and Safety Executive Buxton, UK
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133
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Smith MT, Guyton KZ, Gibbons CF, Fritz JM, Portier CJ, Rusyn I, DeMarini DM, Caldwell JC, Kavlock RJ, Lambert PF, Hecht SS, Bucher JR, Stewart BW, Baan RA, Cogliano VJ, Straif K. Key Characteristics of Carcinogens as a Basis for Organizing Data on Mechanisms of Carcinogenesis. ENVIRONMENTAL HEALTH PERSPECTIVES 2016; 124:713-21. [PMID: 26600562 PMCID: PMC4892922 DOI: 10.1289/ehp.1509912] [Citation(s) in RCA: 375] [Impact Index Per Article: 46.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 11/13/2015] [Indexed: 05/10/2023]
Abstract
BACKGROUND A recent review by the International Agency for Research on Cancer (IARC) updated the assessments of the > 100 agents classified as Group 1, carcinogenic to humans (IARC Monographs Volume 100, parts A-F). This exercise was complicated by the absence of a broadly accepted, systematic method for evaluating mechanistic data to support conclusions regarding human hazard from exposure to carcinogens. OBJECTIVES AND METHODS IARC therefore convened two workshops in which an international Working Group of experts identified 10 key characteristics, one or more of which are commonly exhibited by established human carcinogens. DISCUSSION These characteristics provide the basis for an objective approach to identifying and organizing results from pertinent mechanistic studies. The 10 characteristics are the abilities of an agent to 1) act as an electrophile either directly or after metabolic activation; 2) be genotoxic; 3) alter DNA repair or cause genomic instability; 4) induce epigenetic alterations; 5) induce oxidative stress; 6) induce chronic inflammation; 7) be immunosuppressive; 8) modulate receptor-mediated effects; 9) cause immortalization; and 10) alter cell proliferation, cell death, or nutrient supply. CONCLUSION We describe the use of the 10 key characteristics to conduct a systematic literature search focused on relevant end points and construct a graphical representation of the identified mechanistic information. Next, we use benzene and polychlorinated biphenyls as examples to illustrate how this approach may work in practice. The approach described is similar in many respects to those currently being implemented by the U.S. EPA's Integrated Risk Information System Program and the U.S. National Toxicology Program. CITATION Smith MT, Guyton KZ, Gibbons CF, Fritz JM, Portier CJ, Rusyn I, DeMarini DM, Caldwell JC, Kavlock RJ, Lambert P, Hecht SS, Bucher JR, Stewart BW, Baan R, Cogliano VJ, Straif K. 2016. Key characteristics of carcinogens as a basis for organizing data on mechanisms of carcinogenesis. Environ Health Perspect 124:713-721; http://dx.doi.org/10.1289/ehp.1509912.
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Affiliation(s)
- Martyn T. Smith
- Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, Berkeley, California, USA
| | | | - Catherine F. Gibbons
- Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC, USA, and Research Triangle Park, North Carolina, USA
| | - Jason M. Fritz
- Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC, USA, and Research Triangle Park, North Carolina, USA
| | | | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - David M. DeMarini
- Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC, USA, and Research Triangle Park, North Carolina, USA
| | - Jane C. Caldwell
- Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC, USA, and Research Triangle Park, North Carolina, USA
| | - Robert J. Kavlock
- Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC, USA, and Research Triangle Park, North Carolina, USA
| | - Paul F. Lambert
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Stephen S. Hecht
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, USA
| | - John R. Bucher
- National Toxicology Program, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA
| | - Bernard W. Stewart
- Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Robert A. Baan
- International Agency for Research on Cancer, Lyon, France
| | - Vincent J. Cogliano
- Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC, USA, and Research Triangle Park, North Carolina, USA
| | - Kurt Straif
- International Agency for Research on Cancer, Lyon, France
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134
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Egeghy PP, Sheldon LS, Isaacs KK, Özkaynak H, Goldsmith MR, Wambaugh JF, Judson RS, Buckley TJ. Computational Exposure Science: An Emerging Discipline to Support 21st-Century Risk Assessment. ENVIRONMENTAL HEALTH PERSPECTIVES 2016; 124:697-702. [PMID: 26545029 PMCID: PMC4892918 DOI: 10.1289/ehp.1509748] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 10/30/2015] [Indexed: 05/19/2023]
Abstract
BACKGROUND Computational exposure science represents a frontier of environmental science that is emerging and quickly evolving. OBJECTIVES In this commentary, we define this burgeoning discipline, describe a framework for implementation, and review some key ongoing research elements that are advancing the science with respect to exposure to chemicals in consumer products. DISCUSSION The fundamental elements of computational exposure science include the development of reliable, computationally efficient predictive exposure models; the identification, acquisition, and application of data to support and evaluate these models; and generation of improved methods for extrapolating across chemicals. We describe our efforts in each of these areas and provide examples that demonstrate both progress and potential. CONCLUSIONS Computational exposure science, linked with comparable efforts in toxicology, is ushering in a new era of risk assessment that greatly expands our ability to evaluate chemical safety and sustainability and to protect public health. CITATION Egeghy PP, Sheldon LS, Isaacs KK, Özkaynak H, Goldsmith M-R, Wambaugh JF, Judson RS, Buckley TJ. 2016. Computational exposure science: an emerging discipline to support 21st-century risk assessment. Environ Health Perspect 124:697-702; http://dx.doi.org/10.1289/ehp.1509748.
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Affiliation(s)
- Peter P. Egeghy
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | | | - Kristin K. Isaacs
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | | | - Michael-Rock Goldsmith
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - John F. Wambaugh
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Richard S. Judson
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Timothy J. Buckley
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
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135
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Dorne JLCM, Bottex B, Merten C, Germini A, Georgiadis N, Aiassa E, Martino L, Rhomberg L, Clewell HJ, Greiner M, Suter GW, Whelan M, Hart ADM, Knight D, Agarwal P, Younes M, Alexander J, Hardy AR. Weighing evidence and assessing uncertainties. EFSA J 2016. [DOI: 10.2903/j.efsa.2016.s0511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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136
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Evaluation of food-relevant chemicals in the ToxCast high-throughput screening program. Food Chem Toxicol 2016; 92:188-96. [DOI: 10.1016/j.fct.2016.04.012] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 04/14/2016] [Accepted: 04/16/2016] [Indexed: 11/17/2022]
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137
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Judson R, Houck K, Martin M, Richard AM, Knudsen TB, Shah I, Little S, Wambaugh J, Woodrow Setzer R, Kothiya P, Phuong J, Filer D, Smith D, Reif D, Rotroff D, Kleinstreuer N, Sipes N, Xia M, Huang R, Crofton K, Thomas RS. Editor's Highlight: Analysis of the Effects of Cell Stress and Cytotoxicity on In Vitro Assay Activity Across a Diverse Chemical and Assay Space. Toxicol Sci 2016; 152:323-39. [PMID: 27208079 DOI: 10.1093/toxsci/kfw092] [Citation(s) in RCA: 149] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Chemical toxicity can arise from disruption of specific biomolecular functions or through more generalized cell stress and cytotoxicity-mediated processes. Here, responses of 1060 chemicals including pharmaceuticals, natural products, pesticidals, consumer, and industrial chemicals across a battery of 815 in vitro assay endpoints from 7 high-throughput assay technology platforms were analyzed in order to distinguish between these types of activities. Both cell-based and cell-free assays showed a rapid increase in the frequency of responses at concentrations where cell stress/cytotoxicity responses were observed in cell-based assays. Chemicals that were positive on at least 2 viability/cytotoxicity assays within the concentration range tested (typically up to 100 μM) activated a median of 12% of assay endpoints whereas those that were not cytotoxic in this concentration range activated 1.3% of the assays endpoints. The results suggest that activity can be broadly divided into: (1) specific biomolecular interactions against one or more targets (eg, receptors or enzymes) at concentrations below which overt cytotoxicity-associated activity is observed; and (2) activity associated with cell stress or cytotoxicity, which may result from triggering specific cell stress pathways, chemical reactivity, physico-chemical disruption of proteins or membranes, or broad low-affinity non-covalent interactions. Chemicals showing a greater number of specific biomolecular interactions are generally designed to be bioactive (pharmaceuticals or pesticidal active ingredients), whereas intentional food-use chemicals tended to show the fewest specific interactions. The analyses presented here provide context for use of these data in ongoing studies to predict in vivo toxicity from chemicals lacking extensive hazard assessment.
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Affiliation(s)
- Richard Judson
- *U.S. EPA, National Center for Computational Toxicology, Research Triangle Park, North Carolina;
| | - Keith Houck
- *U.S. EPA, National Center for Computational Toxicology, Research Triangle Park, North Carolina
| | - Matt Martin
- *U.S. EPA, National Center for Computational Toxicology, Research Triangle Park, North Carolina
| | - Ann M Richard
- *U.S. EPA, National Center for Computational Toxicology, Research Triangle Park, North Carolina
| | - Thomas B Knudsen
- *U.S. EPA, National Center for Computational Toxicology, Research Triangle Park, North Carolina
| | - Imran Shah
- *U.S. EPA, National Center for Computational Toxicology, Research Triangle Park, North Carolina
| | - Stephen Little
- *U.S. EPA, National Center for Computational Toxicology, Research Triangle Park, North Carolina
| | - John Wambaugh
- *U.S. EPA, National Center for Computational Toxicology, Research Triangle Park, North Carolina
| | - R Woodrow Setzer
- *U.S. EPA, National Center for Computational Toxicology, Research Triangle Park, North Carolina
| | - Parth Kothiya
- Contractor to the U.S. EPA National Center for Computational Toxicology, Research Triangle Park, North Carolina
| | - Jimmy Phuong
- Contractor to the U.S. EPA National Center for Computational Toxicology, Research Triangle Park, North Carolina
| | - Dayne Filer
- ORISE Fellow at the U.S. EPA National Center for Computational Toxicology, Research Triangle Park, North Carolina
| | - Doris Smith
- *U.S. EPA, National Center for Computational Toxicology, Research Triangle Park, North Carolina
| | - David Reif
- Department of Statistics, North Carolina State University, Raleigh, North Carolina
| | - Daniel Rotroff
- Department of Statistics, North Carolina State University, Raleigh, North Carolina
| | | | - Nisha Sipes
- National Toxicology Program, Research Triangle Park, North Carolina
| | - Menghang Xia
- NIH National Center for Advancing Translational Sciences, Rockville, Maryland
| | - Ruili Huang
- NIH National Center for Advancing Translational Sciences, Rockville, Maryland
| | - Kevin Crofton
- *U.S. EPA, National Center for Computational Toxicology, Research Triangle Park, North Carolina
| | - Russell S Thomas
- *U.S. EPA, National Center for Computational Toxicology, Research Triangle Park, North Carolina
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138
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Yauk CL, Buick JK, Williams A, Swartz CD, Recio L, Li H, Fornace AJ, Thomson EM, Aubrecht J. Application of the TGx-28.65 transcriptomic biomarker to classify genotoxic and non-genotoxic chemicals in human TK6 cells in the presence of rat liver S9. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2016; 57:243-60. [PMID: 26946220 PMCID: PMC5021161 DOI: 10.1002/em.22004] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 02/03/2016] [Accepted: 02/04/2016] [Indexed: 05/05/2023]
Abstract
In vitro transcriptional signatures that predict toxicities can facilitate chemical screening. We previously developed a transcriptomic biomarker (known as TGx-28.65) for classifying agents as genotoxic (DNA damaging) and non-genotoxic in human lymphoblastoid TK6 cells. Because TK6 cells do not express cytochrome P450s, we confirmed accurate classification by the biomarker in cells co-exposed to 1% 5,6 benzoflavone/phenobarbital-induced rat liver S9 for metabolic activation. However, chemicals may require different types of S9 for activation. Here we investigated the response of TK6 cells to higher percentages of Aroclor-, benzoflavone/phenobarbital-, or ethanol-induced rat liver S9 to expand TGx-28.65 biomarker applicability. Transcriptional profiles were derived 3 to 4 hr following a 4 hr co-exposure of TK6 cells to test chemicals and S9. Preliminary studies established that 10% Aroclor- and 5% ethanol-induced S9 alone did not induce the TGx-28.65 biomarker genes. Seven genotoxic and two non-genotoxic chemicals (and concurrent solvent and positive controls) were then tested with one of the S9s (selected based on cell survival and micronucleus induction). Relative survival and micronucleus frequency was assessed by flow cytometry in cells 20 hr post-exposure. Genotoxic/non-genotoxic chemicals were accurately classified using the different S9s. One technical replicate of cells co-treated with dexamethasone and 10% Aroclor-induced S9 was falsely classified as genotoxic, suggesting caution in using high S9 concentrations. Even low concentrations of genotoxic chemicals (those not causing cytotoxicity) were correctly classified, demonstrating that TGx-28.65 is a sensitive biomarker of genotoxicity. A meta-analysis of datasets from 13 chemicals supports that different S9s can be used in TK6 cells, without impairing classification using the TGx-28.65 biomarker.
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Affiliation(s)
- Carole L. Yauk
- Environmental Health Science and Research Bureau, Health CanadaOttawaOntarioCanada
| | - Julie K. Buick
- Environmental Health Science and Research Bureau, Health CanadaOttawaOntarioCanada
| | - Andrew Williams
- Environmental Health Science and Research Bureau, Health CanadaOttawaOntarioCanada
| | - Carol D. Swartz
- Integrated Laboratory Systems IncResearch Triangle ParkNorth Carolina
| | - Leslie Recio
- Integrated Laboratory Systems IncResearch Triangle ParkNorth Carolina
| | - Heng‐Hong Li
- Department of Biochemistry and Molecular and Cellular BiologyGeorgetown University Medical CenterWashingtonDistrict of Columbia
- Department of OncologyGeorgetown University Medical CenterWashingtonDistrict of Columbia
| | - Albert J. Fornace
- Department of Biochemistry and Molecular and Cellular BiologyGeorgetown University Medical CenterWashingtonDistrict of Columbia
- Department of OncologyGeorgetown University Medical CenterWashingtonDistrict of Columbia
| | - Errol M. Thomson
- Environmental Health Science and Research Bureau, Health CanadaOttawaOntarioCanada
| | - Jiri Aubrecht
- Drug Safety Research and Development, Pfizer IncGrotonConnecticut
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139
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Qin C, Tanis KQ, Podtelezhnikov AA, Glaab WE, Sistare FD, DeGeorge JJ. Toxicogenomics in drug development: a match made in heaven? Expert Opin Drug Metab Toxicol 2016; 12:847-9. [PMID: 27050123 DOI: 10.1080/17425255.2016.1175437] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Chunhua Qin
- Safety Assessment and Laboratory Animal Resources, Merck & Co., West Point, PA, USA
| | - Keith Q. Tanis
- Genetics and Pharmacogenomics, Merck & Co., West Point, PA, USA
| | | | - Warren E. Glaab
- Safety Assessment and Laboratory Animal Resources, Merck & Co., West Point, PA, USA
| | - Frank D. Sistare
- Safety Assessment and Laboratory Animal Resources, Merck & Co., West Point, PA, USA
| | - Joseph J. DeGeorge
- Safety Assessment and Laboratory Animal Resources, Merck & Co., West Point, PA, USA
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140
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De Abrew KN, Kainkaryam RM, Shan YK, Overmann GJ, Settivari RS, Wang X, Xu J, Adams RL, Tiesman JP, Carney EW, Naciff JM, Daston GP. Grouping 34 Chemicals Based on Mode of Action Using Connectivity Mapping. Toxicol Sci 2016; 151:447-61. [DOI: 10.1093/toxsci/kfw058] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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141
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White PA, Johnson GE. Genetic toxicology at the crossroads-from qualitative hazard evaluation to quantitative risk assessment. Mutagenesis 2016; 31:233-7. [PMID: 27000791 DOI: 10.1093/mutage/gew011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Applied genetic toxicology is undergoing a transition from qualitative hazard identification to quantitative dose-response analysis and risk assessment. To facilitate this change, the Health and Environmental Sciences Institute (HESI) Genetic Toxicology Technical Committee (GTTC) sponsored a workshop held in Lancaster, UK on July 10-11, 2014. The event included invited speakers from several institutions and the contents was divided into three themes-1: Point-of-departure Metrics for Quantitative Dose-Response Analysis in Genetic Toxicology; 2: Measurement and Estimation of Exposures for Better Extrapolation to Humans and 3: The Use of Quantitative Approaches in Genetic Toxicology for human health risk assessment (HHRA). A host of pertinent issues were discussed relating to the use of in vitro and in vivo dose-response data, the development of methods for in vitro to in vivo extrapolation and approaches to use in vivo dose-response data to determine human exposure limits for regulatory evaluations and decision-making. This Special Issue, which was inspired by the workshop, contains a series of papers that collectively address topics related to the aforementioned themes. The Issue includes contributions that collectively evaluate, describe and discuss in silico, in vitro, in vivo and statistical approaches that are facilitating the shift from qualitative hazard evaluation to quantitative risk assessment. The use and application of the benchmark dose approach was a central theme in many of the workshop presentations and discussions, and the Special Issue includes several contributions that outline novel applications for the analysis and interpretation of genetic toxicity data. Although the contents of the Special Issue constitutes an important step towards the adoption of quantitative methods for regulatory assessment of genetic toxicity, formal acceptance of quantitative methods for HHRA and regulatory decision-making will require consensus regarding the relationships between genetic damage and disease, and the concomitant ability to use genetic toxicity results per se.
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Affiliation(s)
| | - George E Johnson
- Institute of Life Science, Swansea University Medical School, Singleton Park, Swansea SA3 5DE, UK
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142
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Wills JW, Long AS, Johnson GE, Bemis JC, Dertinger SD, Slob W, White PA. Empirical analysis of BMD metrics in genetic toxicology part II: in vivo potency comparisons to promote reductions in the use of experimental animals for genetic toxicity assessment. Mutagenesis 2016; 31:265-75. [PMID: 26984301 DOI: 10.1093/mutage/gew009] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Genotoxicity tests have traditionally been used only for hazard identification, with qualitative dichotomous groupings being used to identify compounds that have the capacity to induce mutations and/or cytogenetic alterations. However, there is an increasing interest in employing quantitative analysis of in vivo dose-response data to derive point of departure (PoD) metrics that can be used to establish human exposure limits or margins of exposure (MOEs), thereby supporting human health risk assessments and regulatory decisions. This work is an extension of our companion article on in vitro dose-response analyses and outlines how the combined benchmark dose (BMD) approach across included covariates can be used to improve the analyses and interpretation of in vivo genetic toxicity dose-response data. Using the BMD-covariate approach, we show that empirical comparisons of micronucleus frequency dose-response data across multiple studies justifies dataset merging, with subsequent analyses improving the precision of BMD estimates and permitting attendant potency ranking of seven clastogens. Similarly, empirical comparisons of Pig-a mutant phenotype frequency data collected in males and females justified dataset merging across sex. This permitted more effective scrutiny regarding the effect of post-exposure sampling time on the mutagenicity of N-ethyl-N-nitrosourea observed in reticulocytes and erythrocytes in the Pig-a assay. The BMD-covariate approach revealed tissue-specific differences in the induction of lacZ transgene mutations in Muta™Mouse specimens exposed to benzo[a]pyrene (BaP), with the results permitting the formulation of mechanistic hypotheses regarding the observed potency ranking. Lastly, we illustrate how historical dose-response data for assessments that examined numerous doses (i.e. induced lacZ mutant frequency (MF) across 10 doses of BaP) can be used to improve the precision of BMDs derived from datasets with far fewer doses (i.e. lacZ MF for 3 doses of dibenz[a,h]anthracene). Collectively, the presented examples illustrate how innovative use of the BMD approach can permit refinement of the use of in vivo data; improving the efficacy of experimental animal use in genetic toxicology without sacrificing PoD precision.
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Affiliation(s)
- John W Wills
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario K1A 0K9, Canada,
| | - Alexandra S Long
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario K1A 0K9, Canada
| | - George E Johnson
- Swansea University Medical School, Institute of Life Science, Swansea SA2 8PP, UK
| | | | | | - Wout Slob
- National Institute for Public Health and the Environment (RIVM), 3720 BA Bilthoven, The Netherlands
| | - Paul A White
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario K1A 0K9, Canada,
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143
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Labib S, Williams A, Yauk CL, Nikota JK, Wallin H, Vogel U, Halappanavar S. Nano-risk Science: application of toxicogenomics in an adverse outcome pathway framework for risk assessment of multi-walled carbon nanotubes. Part Fibre Toxicol 2016; 13:15. [PMID: 26979667 PMCID: PMC4792104 DOI: 10.1186/s12989-016-0125-9] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 03/01/2016] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND A diverse class of engineered nanomaterials (ENMs) exhibiting a wide array of physical-chemical properties that are associated with toxicological effects in experimental animals is in commercial use. However, an integrated framework for human health risk assessment (HHRA) of ENMs has yet to be established. Rodent 2-year cancer bioassays, clinical chemistry, and histopathological endpoints are still considered the 'gold standard' for detecting substance-induced toxicity in animal models. However, the use of data derived from alternative toxicological tools, such as genome-wide expression profiling and in vitro high-throughput assays, are gaining acceptance by the regulatory community for hazard identification and for understanding the underlying mode-of-action. Here, we conducted a case study to evaluate the application of global gene expression data in deriving pathway-based points of departure (PODs) for multi-walled carbon nanotube (MWCNT)-induced lung fibrosis, a non-cancer endpoint of regulatory importance. METHODS Gene expression profiles from the lungs of mice exposed to three individual MWCNTs with different physical-chemical properties were used within the framework of an adverse outcome pathway (AOP) for lung fibrosis to identify key biological events linking MWCNT exposure to lung fibrosis. Significantly perturbed pathways were categorized along the key events described in the AOP. Benchmark doses (BMDs) were calculated for each perturbed pathway and were used to derive transcriptional BMDs for each MWCNT. RESULTS Similar biological pathways were perturbed by the different MWCNT types across the doses and post-exposure time points studied. The pathway BMD values showed a time-dependent trend, with lower BMDs for pathways perturbed at the earlier post-exposure time points (24 h, 3d). The transcriptional BMDs were compared to the apical BMDs derived by the National Institute for Occupational Safety and Health (NIOSH) using alveolar septal thickness and fibrotic lesions endpoints. We found that regardless of the type of MWCNT, the BMD values for pathways associated with fibrosis were 14.0-30.4 μg/mouse, which are comparable to the BMDs derived by NIOSH for MWCNT-induced lung fibrotic lesions (21.0-27.1 μg/mouse). CONCLUSIONS The results demonstrate that transcriptomic data can be used to as an effective mechanism-based method to derive acceptable levels of exposure to nanomaterials in product development when epidemiological data are unavailable.
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Affiliation(s)
- Sarah Labib
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON K1A 0K9 Canada
| | - Andrew Williams
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON K1A 0K9 Canada
| | - Carole L. Yauk
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON K1A 0K9 Canada
| | - Jake K. Nikota
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON K1A 0K9 Canada
| | - Håkan Wallin
- National Research Centre for the Working Environment, Lerso Parkallé 105, DK-2100 Copenhagen, Denmark
- Department of Public Health, University of Copenhagen, DK-1353 Copenhagen K, Denmark
| | - Ulla Vogel
- National Research Centre for the Working Environment, Lerso Parkallé 105, DK-2100 Copenhagen, Denmark
- Department of Micro- and Nanotechnology, Technical University of Denmark, DK-2800 Kgs Lyngby, Denmark
| | - Sabina Halappanavar
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON K1A 0K9 Canada
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144
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Anthony Tony Cox L, Popken DA, Kaplan AM, Plunkett LM, Becker RA. How well can in vitro data predict in vivo effects of chemicals? Rodent carcinogenicity as a case study. Regul Toxicol Pharmacol 2016; 77:54-64. [PMID: 26879462 DOI: 10.1016/j.yrtph.2016.02.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 02/03/2016] [Accepted: 02/07/2016] [Indexed: 12/31/2022]
Abstract
A recent research article by the National Center for Computational Toxicology (NCCT) (Kleinstreuer et al., 2013), indicated that high throughput screening (HTS) data from assays linked to hallmarks and presumed pathways of carcinogenesis could be used to predict classification of pesticides as either (a) possible, probable or likely rodent carcinogens; or (b) not likely carcinogens or evidence of non-carcinogenicity. Using independently developed software to validate the computational results, we replicated the majority of the results reported. We also found that the prediction model correlating cancer pathway bioactivity scores with in vivo carcinogenic effects in rodents was not robust. A change of classification of a single chemical in the test set was capable of changing the overall study conclusion about the statistical significance of the correlation. Furthermore, in the subset of pesticide compounds used in model validation, the accuracy of prediction was no better than chance for about three quarters of the chemicals (those with fewer than 7 positive outcomes in HTS assays representing the 11 histopathological endpoints used in model development), suggesting that the prediction model was not adequate to predict cancer hazard for most of these chemicals. Although the utility of the model for humans is also unclear because a number of the rodent responses modeled (e.g., mouse liver tumors, rat thyroid tumors, rat testicular tumors, etc.) are not considered biologically relevant to human responses, the data examined imply the need for further research with HTS assays and improved models, which might help to predict classifications of in vivo carcinogenic responses in rodents for the pesticide considered, and thus reduce the need for testing in laboratory animals.
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Affiliation(s)
| | | | - A Michael Kaplan
- A. Michael Kaplan & Associates, LLC, 23 Wilkinson Drive, Landenberg, PA, 19350, USA.
| | - Laura M Plunkett
- Integrative Biostrategies LLC, 1127 Eldridge Parkway, Suite 300-335, Houston, TX, 77077, USA.
| | - Richard A Becker
- American Chemistry Council, 700 Second Street NE, Washington, D.C. 20002, USA.
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145
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Grafström RC, Nymark P, Hongisto V, Spjuth O, Ceder R, Willighagen E, Hardy B, Kaski S, Kohonen P. Toward the Replacement of Animal Experiments through the Bioinformatics-driven Analysis of 'Omics' Data from Human Cell Cultures. Altern Lab Anim 2016; 43:325-32. [PMID: 26551289 DOI: 10.1177/026119291504300506] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
This paper outlines the work for which Roland Grafström and Pekka Kohonen were awarded the 2014 Lush Science Prize. The research activities of the Grafström laboratory have, for many years, covered cancer biology studies, as well as the development and application of toxicity-predictive in vitro models to determine chemical safety. Through the integration of in silico analyses of diverse types of genomics data (transcriptomic and proteomic), their efforts have proved to fit well into the recently-developed Adverse Outcome Pathway paradigm. Genomics analysis within state-of-the-art cancer biology research and Toxicology in the 21st Century concepts share many technological tools. A key category within the Three Rs paradigm is the Replacement of animals in toxicity testing with alternative methods, such as bioinformatics-driven analyses of data obtained from human cell cultures exposed to diverse toxicants. This work was recently expanded within the pan-European SEURAT-1 project (Safety Evaluation Ultimately Replacing Animal Testing), to replace repeat-dose toxicity testing with data-rich analyses of sophisticated cell culture models. The aims and objectives of the SEURAT project have been to guide the application, analysis, interpretation and storage of 'omics' technology-derived data within the service-oriented sub-project, ToxBank. Particularly addressing the Lush Science Prize focus on the relevance of toxicity pathways, a 'data warehouse' that is under continuous expansion, coupled with the development of novel data storage and management methods for toxicology, serve to address data integration across multiple 'omics' technologies. The prize winners' guiding principles and concepts for modern knowledge management of toxicological data are summarised. The translation of basic discovery results ranged from chemical-testing and material-testing data, to information relevant to human health and environmental safety.
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Affiliation(s)
- Roland C Grafström
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Penny Nymark
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Vesa Hongisto
- Toxicology Department, Misvik Biology Corporation, Turku, Finland
| | - Ola Spjuth
- Department of Medical Epidemiology and Biostatistics, Swedish e-Science Research Centre, Karolinska Institutet, Stockholm, Sweden and Department of Pharmaceutical Biosciences and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Rebecca Ceder
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Egon Willighagen
- Department of Bioinformatics-BiGCat, Maastricht University, Maastricht, The Netherlands
| | - Barry Hardy
- Douglas Connect GmbH, Zeiningen, Switzerland
| | - Samuel Kaski
- Helsinki Institute for Information Technology, Aalto University, Department of Computer Science, Helsinki, Finland
| | - Pekka Kohonen
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
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146
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Integrated Approaches to Testing and Assessment. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 856:317-342. [PMID: 27671729 DOI: 10.1007/978-3-319-33826-2_13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In this chapter, we explain how Integrated Approaches to Testing and Assessment (IATA) offer a means of integrating and translating the data generated by toxicity testing methods, thereby serving as flexible and suitable tools for toxicological decision making in the twenty-first century. In addition to traditional in vitro and in vivo testing methods, IATA are increasingly incorporating newly developed in vitro systems and measurement technologies such as high throughput screening and high content imaging. Computational approaches are also being used in IATA development, both as a means of generating data (e.g. QSARs), interpreting data (bioinformatics and chemoinformatics), and as a means of integrating multiple sources of data (e.g. expert systems, bayesian models). Decision analytic methods derived from socioeconomic theory can also play a role in developing flexible and optimal IATA solutions. Some of the challenges involved in the development, validation and implementation of IATA are also discussed.
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147
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Wills JW, Johnson GE, Doak SH, Soeteman-Hernández LG, Slob W, White PA. Empirical analysis of BMD metrics in genetic toxicology part I: in vitro analyses to provide robust potency rankings and support MOA determinations. Mutagenesis 2015; 31:255-63. [PMID: 26687511 DOI: 10.1093/mutage/gev085] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Genetic toxicity testing has traditionally been used for hazard identification, with dichotomous classification of test results serving to identify genotoxic agents. However, the utility of genotoxicity data can be augmented by employing dose-response analysis and point of departure determination. Via interpolation from a fitted dose-response model, the benchmark dose (BMD) approach estimates the dose that elicits a specified (small) effect size. BMD metrics and their confidence intervals can be used for compound potency ranking within an endpoint, as well as potency comparisons across other factors such as cell line or exposure duration. A recently developed computational method, the BMD covariate approach, permits combined analysis of multiple dose-response data sets that are differentiated by covariates such as compound, cell type or exposure regime. The approach provides increased BMD precision for effective potency rankings across compounds and other covariates that pertain to a hypothesised mode of action (MOA). To illustrate these applications, the covariate approach was applied to the analysis of published in vitro micronucleus frequency dose-response data for ionising radiations, a set of aneugens, two mutagenic azo compounds and a topoisomerase II inhibitor. The ionising radiation results show that the precision of BMD estimates can be improved by employing the covariate method. The aneugen analysis provided potency groupings based on the BMD confidence intervals, and analyses of azo compound data from cells lines with differing metabolic capacity confirmed the influence of endogenous metabolism on genotoxic potency. This work, which is the first of a two-part series, shows that BMD-derived potency rankings can be employed to support MOA evaluations as well as facilitate read across to expedite chemical evaluations and regulatory decision-making. The follow-up (Part II) employs the combined covariate approach to analyse in vivo genetic toxicity dose-response data focussing on how improvements in BMD precision can impact the reduction and refinement of animal use in toxicological research.
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Affiliation(s)
- John W Wills
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Canada
| | - George E Johnson
- Institute of Life Science, Swansea University Medical School, Swansea, UK and
| | - Shareen H Doak
- Institute of Life Science, Swansea University Medical School, Swansea, UK and
| | | | - Wout Slob
- National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
| | - Paul A White
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Canada,
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148
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Kuo B, Francina Webster A, Thomas RS, Yauk CL. BMDExpress Data Viewer - a visualization tool to analyze BMDExpress datasets. J Appl Toxicol 2015; 36:1048-59. [PMID: 26671443 PMCID: PMC5064610 DOI: 10.1002/jat.3265] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 10/15/2015] [Accepted: 10/16/2015] [Indexed: 12/13/2022]
Abstract
Regulatory agencies increasingly apply benchmark dose (BMD) modeling to determine points of departure for risk assessment. BMDExpress applies BMD modeling to transcriptomic datasets to identify transcriptional BMDs. However, graphing and analytical capabilities within BMDExpress are limited, and the analysis of output files is challenging. We developed a web‐based application, BMDExpress Data Viewer (http://apps.sciome.com:8082/BMDX_Viewer/), for visualizing and graphing BMDExpress output files. The application consists of “Summary Visualization” and “Dataset Exploratory” tools. Through analysis of transcriptomic datasets of the toxicants furan and 4,4′‐methylenebis(N,N‐dimethyl)benzenamine, we demonstrate that the “Summary Visualization Tools” can be used to examine distributions of gene and pathway BMD values, and to derive a potential point of departure value based on summary statistics. By applying filters on enrichment P‐values and minimum number of significant genes, the “Functional Enrichment Analysis” tool enables the user to select biological processes or pathways that are selectively perturbed by chemical exposure and identify the related BMD. The “Multiple Dataset Comparison” tool enables comparison of gene and pathway BMD values across multiple experiments (e.g., across timepoints or tissues). The “BMDL‐BMD Range Plotter” tool facilitates the observation of BMD trends across biological processes or pathways. Through our case studies, we demonstrate that BMDExpress Data Viewer is a useful tool to visualize, explore and analyze BMDExpress output files. Visualizing the data in this manner enables rapid assessment of data quality, model fit, doses of peak activity, most sensitive pathway perturbations and other metrics that will be useful in applying toxicogenomics in risk assessment. © 2015 Her Majesty the Queen in Right of Canada. Journal of Applied Toxicology published by John Wiley & Sons, Ltd. We developed BMDExpress Data Viewer, which contains two collections of tools, “Summary Visualization Tools” and “Dataset Exploratory Tools,” to visualize and analyze BMDExpress output files. Through two case studies, we demonstrate the capabilities of graphically examining transcriptomic dose–response datasets in a risk assessment context by comparing and observing trends in transcriptomic benchmark doses (BMDs) for biological processes and pathways. Our results illustrate that BMDExpress Data Viewer is a useful tool to visualize, explore and analyze BMDExpress output files.
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Affiliation(s)
- Byron Kuo
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, Canada, K1A 0K9
| | - A Francina Webster
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, Canada, K1A 0K9.,Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, K1S 5B6, Canada
| | - Russell S Thomas
- United States Environmental Protection Agency, Office of Research and Development, National Center for Computational Toxicology, Research Triangle Park, NC, 27711, USA
| | - Carole L Yauk
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, Canada, K1A 0K9
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149
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Lake AD, Wood CE, Bhat VS, Chorley BN, Carswell GK, Sey YM, Kenyon EM, Padnos B, Moore TM, Tennant AH, Schmid JE, George BJ, Ross DG, Hughes MF, Corton JC, Simmons JE, McQueen CA, Hester SD. Dose and Effect Thresholds for Early Key Events in a PPARα-Mediated Mode of Action. Toxicol Sci 2015; 149:312-25. [PMID: 26519955 DOI: 10.1093/toxsci/kfv236] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Current strategies for predicting adverse health outcomes of environmental chemicals are centered on early key events in toxicity pathways. However, quantitative relationships between early molecular changes in a given pathway and later health effects are often poorly defined. The goal of this study was to evaluate short-term key event indicators using qualitative and quantitative methods in an established pathway of mouse liver tumorigenesis mediated by peroxisome proliferator-activated receptor alpha (PPARα). Male B6C3F1 mice were exposed for 7 days to di (2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DNOP), and n-butyl benzyl phthalate (BBP), which vary in PPARα activity and liver tumorigenicity. Each phthalate increased expression of select PPARα target genes at 7 days, while only DEHP significantly increased liver cell proliferation labeling index (LI). Transcriptional benchmark dose (BMDT) estimates for dose-related genomic markers stratified phthalates according to hypothetical tumorigenic potencies, unlike BMDs for non-genomic endpoints (relative liver weights or proliferation). The 7-day BMDT values for Acot1 as a surrogate measure for PPARα activation were 29, 370, and 676 mg/kg/day for DEHP, DNOP, and BBP, respectively, distinguishing DEHP (liver tumor BMD of 35 mg/kg/day) from non-tumorigenic DNOP and BBP. Effect thresholds were generated using linear regression of DEHP effects at 7 days and 2-year tumor incidence values to anchor early response molecular indicators and a later phenotypic outcome. Thresholds varied widely by marker, from 2-fold (Pdk4 and proliferation LI) to 30-fold (Acot1) induction to reach hypothetical tumorigenic expression levels. These findings highlight key issues in defining thresholds for biological adversity based on molecular changes.
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Affiliation(s)
- April D Lake
- *Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina 27599; Oak Ridge Institute for Science and Education (ORISE) participant at the National Health and Environmental Effects Research Laboratory (NHEERL), Office of Research and Development (ORD), U.S. Environmental Protection Agency (U.S. EPA), Research Triangle Park, North Carolina 27711; Integrated Systems Toxicology Division, NHEERL, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711
| | - Charles E Wood
- Integrated Systems Toxicology Division, NHEERL, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711
| | | | - Brian N Chorley
- Integrated Systems Toxicology Division, NHEERL, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711
| | - Gleta K Carswell
- Integrated Systems Toxicology Division, NHEERL, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711
| | - Yusupha M Sey
- Integrated Systems Toxicology Division, NHEERL, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711
| | - Elaina M Kenyon
- Integrated Systems Toxicology Division, NHEERL, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711
| | - Beth Padnos
- Integrated Systems Toxicology Division, NHEERL, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711
| | - Tanya M Moore
- Integrated Systems Toxicology Division, NHEERL, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711
| | - Alan H Tennant
- Integrated Systems Toxicology Division, NHEERL, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711
| | | | - Barbara Jane George
- Office of the Associate Director for Health, NHEERL, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711
| | - David G Ross
- Integrated Systems Toxicology Division, NHEERL, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711
| | - Michael F Hughes
- Integrated Systems Toxicology Division, NHEERL, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711
| | - J Christopher Corton
- Integrated Systems Toxicology Division, NHEERL, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711
| | - Jane Ellen Simmons
- Integrated Systems Toxicology Division, NHEERL, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711
| | - Charlene A McQueen
- Integrated Systems Toxicology Division, NHEERL, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711
| | - Susan D Hester
- Integrated Systems Toxicology Division, NHEERL, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711;
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150
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Doe JE, Lander DR, Doerrer NG, Heard N, Hines RN, Lowit AB, Pastoor T, Phillips RD, Sargent D, Sherman JH, Young Tanir J, Embry MR. Use of the RISK21 roadmap and matrix: human health risk assessment of the use of a pyrethroid in bed netting. Crit Rev Toxicol 2015; 46:54-73. [PMID: 26517449 PMCID: PMC4732465 DOI: 10.3109/10408444.2015.1082974] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The HESI-coordinated RISK21 roadmap and matrix are tools that provide a transparent method to compare exposure and toxicity information and assess whether additional refinement is required to obtain the necessary precision level for a decision regarding safety. A case study of the use of a pyrethroid, "pseudomethrin," in bed netting to control malaria is presented to demonstrate the application of the roadmap and matrix. The evaluation began with a problem formulation step. The first assessment utilized existing information pertaining to the use and the class of chemistry. At each stage of the step-wise approach, the precision of the toxicity and exposure estimates were refined as necessary by obtaining key data which enabled a decision on safety to be made efficiently and with confidence. The evaluation demonstrated the concept of using existing information within the RISK21 matrix to drive the generation of additional data using a value-of-information approach. The use of the matrix highlighted whether exposure or toxicity required further investigation and emphasized the need to address the default uncertainty factor of 100 at the highest tier of the evaluation. It also showed how new methodology such as the use of in vitro studies and assays could be used to answer the specific questions which arise through the use of the matrix. The matrix also serves as a useful means to communicate progress to stakeholders during an assessment of chemical use.
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Affiliation(s)
- John E Doe
- a Parker Doe Partnership LLP , Frodsham , Cheshire , UK
| | - Deborah R Lander
- b DuPont Haskell Global Centers for Health & Environmental Sciences , Newark , DE , USA
| | - Nancy G Doerrer
- c ILSI Health and Environmental Sciences Institute , Washington, DC , USA
| | - Nina Heard
- d Syngenta Crop Protection LLC , Greensboro , NC , USA
| | - Ronald N Hines
- e US Environmental Protection Agency, NHEERL, Research Triangle Park , USA
| | - Anna B Lowit
- f US Environmental Protection Agency, Office of Pesticide Programs , Washington, DC , USA
| | | | | | - Dana Sargent
- h Arysta LifeScience North America , Cary , NC , USA , and
| | | | | | - Michelle R Embry
- c ILSI Health and Environmental Sciences Institute , Washington, DC , USA
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