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Kreutz A, Oyetade OB, Chang X, Hsieh JH, Behl M, Allen DG, Kleinstreuer NC, Hogberg HT. Integrated Approach for Testing and Assessment for Developmental Neurotoxicity (DNT) to Prioritize Aromatic Organophosphorus Flame Retardants. TOXICS 2024; 12:437. [PMID: 38922117 PMCID: PMC11209292 DOI: 10.3390/toxics12060437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Revised: 06/13/2024] [Accepted: 06/14/2024] [Indexed: 06/27/2024]
Abstract
Organophosphorus flame retardants (OPFRs) are abundant and persistent in the environment but have limited toxicity information. Their similarity in structure to organophosphate pesticides presents great concern for developmental neurotoxicity (DNT). However, current in vivo testing is not suitable to provide DNT information on the amount of OPFRs that lack data. Over the past decade, an in vitro battery was developed to enhance DNT assessment, consisting of assays that evaluate cellular processes in neurodevelopment and function. In this study, behavioral data of small model organisms were also included. To assess if these assays provide sufficient mechanistic coverage to prioritize chemicals for further testing and/or identify hazards, an integrated approach to testing and assessment (IATA) was developed with additional information from the Integrated Chemical Environment (ICE) and the literature. Human biomonitoring and exposure data were identified and physiologically-based toxicokinetic models were applied to relate in vitro toxicity data to human exposure based on maximum plasma concentration. Eight OPFRs were evaluated, including aromatic OPFRs (triphenyl phosphate (TPHP), isopropylated phenyl phosphate (IPP), 2-ethylhexyl diphenyl phosphate (EHDP), tricresyl phosphate (TMPP), isodecyl diphenyl phosphate (IDDP), tert-butylphenyl diphenyl phosphate (BPDP)) and halogenated FRs ((Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), tris(2-chloroethyl) phosphate (TCEP)). Two representative brominated flame retardants (BFRs) (2,2'4,4'-tetrabromodiphenyl ether (BDE-47) and 3,3',5,5'-tetrabromobisphenol A (TBBPA)) with known DNT potential were selected for toxicity benchmarking. Data from the DNT battery indicate that the aromatic OPFRs have activity at similar concentrations as the BFRs and should therefore be evaluated further. However, these assays provide limited information on the mechanism of the compounds. By integrating information from ICE and the literature, endocrine disruption was identified as a potential mechanism. This IATA case study indicates that human exposure to some OPFRs could lead to a plasma concentration similar to those exerting in vitro activities, indicating potential concern for human health.
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Affiliation(s)
- Anna Kreutz
- Inotiv, Research Triangle Park, NC 27560, USA; (A.K.); (O.B.O.); (X.C.); (D.G.A.)
| | - Oluwakemi B. Oyetade
- Inotiv, Research Triangle Park, NC 27560, USA; (A.K.); (O.B.O.); (X.C.); (D.G.A.)
| | - Xiaoqing Chang
- Inotiv, Research Triangle Park, NC 27560, USA; (A.K.); (O.B.O.); (X.C.); (D.G.A.)
| | - Jui-Hua Hsieh
- NIH/NIEHS/DTT/PTB, Research Triangle Park, NC 27560, USA;
| | - Mamta Behl
- Neurocrine Biosciences Inc., San Diego, CA 92130, USA;
| | - David G. Allen
- Inotiv, Research Triangle Park, NC 27560, USA; (A.K.); (O.B.O.); (X.C.); (D.G.A.)
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Martin MM, Carpenter AF, Shafer TJ, Paul Friedman K, Carstens KE. Chemical effects on neural network activity: Comparison of acute versus network formation exposure in microelectrode array assays. Toxicology 2024; 505:153842. [PMID: 38788893 DOI: 10.1016/j.tox.2024.153842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/08/2024] [Accepted: 05/21/2024] [Indexed: 05/26/2024]
Abstract
New approach methodologies (NAMs) can address information gaps on potential neurotoxicity or developmental neurotoxicity hazard for data-poor chemicals. Two assays have been previously developed using microelectrode arrays (MEA), a technology which measures neural activity. The MEA acute network function assay (AcN) uses dissociated rat cortical cells cultured at postnatal day 0 and evaluates network activity during a 40-minute chemical exposure on day in vitro (DIV)13 or 15. In contrast, the MEA network formation assay (NFA) uses a developmental exposure paradigm spanning DIV0 through DIV12. Measures of network activity over time at DIV5, 7, 9, and 12 in the NFA are reduced to an estimated area under the curve to facilitate concentration-response evaluation. Here, we evaluated the hypothesis that chemicals with effects in the AcN also perturb the NFA by examining quantitative and qualitative concordance between assays. Out of 243 chemicals screened in both assays, we observed 70.3% concordance between the AcN and NFA after eliminating activity inferred to be cytotoxic (selective activity), with the majority of discordance explained by chemicals that altered selective activity in the AcN but not NFA. The NFA detected more active chemicals when evaluating activity associated with cytotoxicity. Median potency values were lower in the NFA compared to the AcN, but within-chemical potency values were not uniformly lower in the NFA than the AcN. Lastly, the AcN and NFA captured unique bioactivity fingerprints; the AcN was more informative for identifying chemicals with a shared mode of action, while the NFA provided information relevant to developmental exposure. Taken together, this analysis provides a rationale for using both approaches for chemical evaluation with consideration of the context of use, such as screening/ prioritization, hazard identification, or to address questions regarding biological mechanism or function.
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Affiliation(s)
- Melissa M Martin
- Computational Toxicology & Bioinformatics Branch, Biomolecular and Computational Toxicology Division, CCTE/ORD, US. Environmental Protection Agency, Research Triangle Park, NC 27711, USA
| | - Amy F Carpenter
- Computational Toxicology & Bioinformatics Branch, Biomolecular and Computational Toxicology Division, CCTE/ORD, US. Environmental Protection Agency, Research Triangle Park, NC 27711, USA; Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN, USA
| | - Timothy J Shafer
- Computational Toxicology & Bioinformatics Branch, Biomolecular and Computational Toxicology Division, CCTE/ORD, US. Environmental Protection Agency, Research Triangle Park, NC 27711, USA
| | - Katie Paul Friedman
- Computational Toxicology & Bioinformatics Branch, Biomolecular and Computational Toxicology Division, CCTE/ORD, US. Environmental Protection Agency, Research Triangle Park, NC 27711, USA
| | - Kelly E Carstens
- Computational Toxicology & Bioinformatics Branch, Biomolecular and Computational Toxicology Division, CCTE/ORD, US. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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Wu X, Chen Y, Kreutz A, Silver B, Tokar EJ. Pluripotent stem cells for target organ developmental toxicity testing. Toxicol Sci 2024; 199:163-171. [PMID: 38547390 PMCID: PMC11131012 DOI: 10.1093/toxsci/kfae037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024] Open
Abstract
Prenatal developmental toxicity research focuses on understanding the potential adverse effects of environmental agents, drugs, and chemicals on the development of embryos and fetuses. Traditional methods involve animal testing, but ethical concerns and the need for human-relevant models have prompted the exploration of alternatives. Pluripotent stem cells (PSCs) are versatile cells with the unique ability to differentiate into any cell type, serving as a foundational tool for studying human development. Two-dimensional (2D) PSC models are often chosen for their ease of use and reproducibility for high-throughput screening. However, they lack the complexity of an in vivo environment. Alternatively, three-dimensional (3D) PSC models, such as organoids, offer tissue architecture and intercellular communication more reminiscent of in vivo conditions. However, they are complicated to produce and analyze, usually requiring advanced and expensive techniques. This review discusses recent advances in the use of human PSCs differentiated into brain and heart lineages and emerging tools and methods that can be combined with PSCs to help address important scientific questions in the area of developmental toxicology. These advancements and new approach methods align with the push for more relevant and predictive developmental toxicity assessment, combining innovative techniques with organoid models to advance regulatory decision-making.
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Affiliation(s)
- Xian Wu
- Mechanistic Toxicology Branch, Division of Translational Toxicology, NIEHS, Research Triangle Park, North Carolina 27709, USA
- Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, North Carolina 27834, USA
| | - Yichang Chen
- Mechanistic Toxicology Branch, Division of Translational Toxicology, NIEHS, Research Triangle Park, North Carolina 27709, USA
| | - Anna Kreutz
- Mechanistic Toxicology Branch, Division of Translational Toxicology, NIEHS, Research Triangle Park, North Carolina 27709, USA
- Inotiv, Research Triangle Park, North Carolina 27560, USA
| | - Brian Silver
- Mechanistic Toxicology Branch, Division of Translational Toxicology, NIEHS, Research Triangle Park, North Carolina 27709, USA
| | - Erik J Tokar
- Mechanistic Toxicology Branch, Division of Translational Toxicology, NIEHS, Research Triangle Park, North Carolina 27709, USA
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Serafini MM, Sepehri S, Midali M, Stinckens M, Biesiekierska M, Wolniakowska A, Gatzios A, Rundén-Pran E, Reszka E, Marinovich M, Vanhaecke T, Roszak J, Viviani B, SenGupta T. Recent advances and current challenges of new approach methodologies in developmental and adult neurotoxicity testing. Arch Toxicol 2024; 98:1271-1295. [PMID: 38480536 DOI: 10.1007/s00204-024-03703-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 02/06/2024] [Indexed: 03/27/2024]
Abstract
Adult neurotoxicity (ANT) and developmental neurotoxicity (DNT) assessments aim to understand the adverse effects and underlying mechanisms of toxicants on the human nervous system. In recent years, there has been an increasing focus on the so-called new approach methodologies (NAMs). The Organization for Economic Co-operation and Development (OECD), together with European and American regulatory agencies, promote the use of validated alternative test systems, but to date, guidelines for regulatory DNT and ANT assessment rely primarily on classical animal testing. Alternative methods include both non-animal approaches and test systems on non-vertebrates (e.g., nematodes) or non-mammals (e.g., fish). Therefore, this review summarizes the recent advances of NAMs focusing on ANT and DNT and highlights the potential and current critical issues for the full implementation of these methods in the future. The status of the DNT in vitro battery (DNT IVB) is also reviewed as a first step of NAMs for the assessment of neurotoxicity in the regulatory context. Critical issues such as (i) the need for test batteries and method integration (from in silico and in vitro to in vivo alternatives, e.g., zebrafish, C. elegans) requiring interdisciplinarity to manage complexity, (ii) interlaboratory transferability, and (iii) the urgent need for method validation are discussed.
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Affiliation(s)
- Melania Maria Serafini
- Department of Pharmacological and Biomolecular Sciences, "Rodolfo Paoletti", Università degli Studi di Milano, Milan, Italy.
| | - Sara Sepehri
- Department of In Vitro Toxicology and Dermato-Cosmetology (IVTD), Vrije Universiteit Brussels, Brussels, Belgium
| | - Miriam Midali
- Department of Pharmacological and Biomolecular Sciences, "Rodolfo Paoletti", Università degli Studi di Milano, Milan, Italy
| | - Marth Stinckens
- Department of In Vitro Toxicology and Dermato-Cosmetology (IVTD), Vrije Universiteit Brussels, Brussels, Belgium
| | - Marta Biesiekierska
- Department of Translational Research, Nofer Institute of Occupational Medicine, Lodz, Poland
| | - Anna Wolniakowska
- Department of Translational Research, Nofer Institute of Occupational Medicine, Lodz, Poland
| | - Alexandra Gatzios
- Department of In Vitro Toxicology and Dermato-Cosmetology (IVTD), Vrije Universiteit Brussels, Brussels, Belgium
| | - Elise Rundén-Pran
- The Climate and Environmental Research Institute NILU, Kjeller, Norway
| | - Edyta Reszka
- Department of Translational Research, Nofer Institute of Occupational Medicine, Lodz, Poland
| | - Marina Marinovich
- Department of Pharmacological and Biomolecular Sciences, "Rodolfo Paoletti", Università degli Studi di Milano, Milan, Italy
- Center of Research on New Approach Methodologies (NAMs) in chemical risk assessment (SAFE-MI), Università degli Studi di Milano, Milan, Italy
| | - Tamara Vanhaecke
- Department of In Vitro Toxicology and Dermato-Cosmetology (IVTD), Vrije Universiteit Brussels, Brussels, Belgium
| | - Joanna Roszak
- Department of Translational Research, Nofer Institute of Occupational Medicine, Lodz, Poland
| | - Barbara Viviani
- Department of Pharmacological and Biomolecular Sciences, "Rodolfo Paoletti", Università degli Studi di Milano, Milan, Italy
- Center of Research on New Approach Methodologies (NAMs) in chemical risk assessment (SAFE-MI), Università degli Studi di Milano, Milan, Italy
| | - Tanima SenGupta
- The Climate and Environmental Research Institute NILU, Kjeller, Norway
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Green ML, Kluever A, Chen C, Dobreniecki S, Halpern W, Hannas B, Hoberman A, McNerney ME, Mitchell-Ryan S, Shafer TJ, Van Cruchten S, White T. HESI workshop summary: Interpretation of developmental and reproductive toxicity endpoints and the impact on data interpretation of adverse events. Birth Defects Res 2024; 116:e2311. [PMID: 38343152 DOI: 10.1002/bdr2.2311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 01/05/2024] [Accepted: 01/21/2024] [Indexed: 02/15/2024]
Abstract
The Health and Environmental Sciences Institute Developmental and Reproductive Toxicology (HESI-DART) group held a hybrid in-person and virtual workshop in Washington, DC, in 2022. The workshop was entitled, "Interpretation of DART in Regulatory Contexts and Frameworks." There were 154 participants (37 in person and 117 virtual) across 9 countries. The purpose of the workshop was to capture key consensus approaches used to assess DART risks associated with chemical product exposure when a nonclinical finding is identified. The decision-making process for determining whether a DART endpoint is considered adverse is critical because the outcome may have downstream implications (e.g., increased animal usage, modifications to reproductive classification and pregnancy labeling, impact on enrollment in clinical trials and value chains). The workshop included a series of webinar modules to train and engage in discussions with federal and international regulators, clinicians, academic investigators, nongovernmental organizations, contract research organization scientists, and private sector scientists on the best practices and principles of interpreting DART and new approach methodologies in the context of regulatory requirements and processes. Despite the differences in regulatory frameworks between the chemical and pharmaceutical sectors, the same foundational principles for data interpretation should be applied. The discussions led to the categorization of principles, which offer guidance for the systematic interpretation of data. Step 1 entails identifying any hazard by closely analyzing the data at the study endpoint level, while Step 2 involves assessing risk using weight of evidence. These guiding principles were derived from the collective outcomes of the workshop deliberations.
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Affiliation(s)
- M L Green
- Hurley Consulting Associates, Ltd., Summit, New Jersey, USA
| | - A Kluever
- Office of Environmental Management, Department of Energy, Germantown, Maryland, USA
| | - Connie Chen
- Health and Environmental Sciences Institute, Washington, DC, USA
| | - S Dobreniecki
- U.S. Environmental Protection Agency, Office of Pesticide Programs and Office of Research and Development, Washington, DC, USA
| | - Wendy Halpern
- Genentech, A Member of the Roche Group, South San Francisco, California, USA
| | | | - Alan Hoberman
- Charles River Laboratories, Inc., Horsham, Pennsylvania, USA
| | - M E McNerney
- U.S. Food and Drug Administration, Center for Drug Evaluation and Research, Office of New Drugs, Office of Rare Diseases, Pediatrics, Urologic and Reproductive Medicine, Division of Pharmacology-Toxicology for Rare Diseases, Pediatrics, Urologic and Reproductive Medicine/Specialty Medicine, Silver Spring, Maryland, USA, Silver Spring, Maryland, USA
| | - S Mitchell-Ryan
- Health and Environmental Sciences Institute, Washington, DC, USA
| | - T J Shafer
- Biomolecular and Computational Toxicology Division, Center for Computational Toxicology and Exposure, Research Triangle Park, North Carolina, USA
| | | | - Tacey White
- Tacey White Toxicology Consultant, LLC, Glenside, Pennsylvania, USA
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Pitzer EM, Shafer TJ, Herr DW. Identification of neurotoxicology (NT)/developmental neurotoxicology (DNT) adverse outcome pathways and key event linkages with in vitro DNT screening assays. Neurotoxicology 2023; 99:184-194. [PMID: 37866692 DOI: 10.1016/j.neuro.2023.10.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 08/14/2023] [Accepted: 10/13/2023] [Indexed: 10/24/2023]
Abstract
There is a need to assess compounds reliably and quickly for neurotoxicity (NT) and developmental neurotoxicity (DNT). Adverse outcome pathways (AOPs) enable the mapping of molecular events to an apical endpoint in a chemical agnostic manner and have begun to be applied in NT and DNT testing frameworks. We assessed the status of NT/DNT AOPs in the AOP-Wiki (ca. 2/1/23; https://aopwiki.org/), to characterize the state of AOP development, identify strengths and knowledge gaps, elucidate areas for improvement, and describe areas for future focus. AOPs in the Wiki database were assessed for inclusion of NT/DNT molecular events and endpoints, AOP development and endorsement, as well as the linkages of key neurodevelopmental processes with in vitro new approach methods (NAMs). This review found that 41 AOPs have been proposed detailing NT/DNT, of which eight were endorsed by working parties in OECD. Further, this review determined that learning and memory is included as an adverse outcome in eight NT/DNT AOPS, often without distinction regarding the varying forms of learning and memory, regional specification, temporal dynamics, or acquisition mechanisms involved. There is also an overlap with key events (KEs) and in vitro NAMs, which synaptogenesis appeared as a common process. Overall, progress on NT/DNT AOPs could be expanded, adding in modes of action that are missing, improvement in defining apical endpoints, as well as utilizing NAMs further to develop AOPs and identify gaps in current knowledge.
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Affiliation(s)
- Emily M Pitzer
- Center for Public Health and Environmental Assessment, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
| | - Timothy J Shafer
- Center for Computational Toxicology and Exposure, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA
| | - David W Herr
- Center for Public Health and Environmental Assessment, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA
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Feshuk M, Kolaczkowski L, Dunham K, Davidson-Fritz SE, Carstens KE, Brown J, Judson RS, Paul Friedman K. The ToxCast pipeline: updates to curve-fitting approaches and database structure. FRONTIERS IN TOXICOLOGY 2023; 5:1275980. [PMID: 37808181 PMCID: PMC10552852 DOI: 10.3389/ftox.2023.1275980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 09/08/2023] [Indexed: 10/10/2023] Open
Abstract
Introduction: The US Environmental Protection Agency Toxicity Forecaster (ToxCast) program makes in vitro medium- and high-throughput screening assay data publicly available for prioritization and hazard characterization of thousands of chemicals. The assays employ a variety of technologies to evaluate the effects of chemical exposure on diverse biological targets, from distinct proteins to more complex cellular processes like mitochondrial toxicity, nuclear receptor signaling, immune responses, and developmental toxicity. The ToxCast data pipeline (tcpl) is an open-source R package that stores, manages, curve-fits, and visualizes ToxCast data and populates the linked MySQL Database, invitrodb. Methods: Herein we describe major updates to tcpl and invitrodb to accommodate a new curve-fitting approach. The original tcpl curve-fitting models (constant, Hill, and gain-loss models) have been expanded to include Polynomial 1 (Linear), Polynomial 2 (Quadratic), Power, Exponential 2, Exponential 3, Exponential 4, and Exponential 5 based on BMDExpress and encoded by the R package dependency, tcplfit2. Inclusion of these models impacted invitrodb (beta version v4.0) and tcpl v3 in several ways: (1) long-format storage of generic modeling parameters to permit additional curve-fitting models; (2) updated logic for winning model selection; (3) continuous hit calling logic; and (4) removal of redundant endpoints as a result of bidirectional fitting. Results and discussion: Overall, the hit call and potency estimates were largely consistent between invitrodb v3.5 and 4.0. Tcpl and invitrodb provide a standard for consistent and reproducible curve-fitting and data management for diverse, targeted in vitro assay data with readily available documentation, thus enabling sharing and use of these data in myriad toxicology applications. The software and database updates described herein promote comparability across multiple tiers of data within the US Environmental Protection Agency CompTox Blueprint.
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Affiliation(s)
- M. Feshuk
- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, Durham, NC, United States
| | - L. Kolaczkowski
- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, Durham, NC, United States
- National Student Services Contractor, Oak Ridge Associated Universities, Oak Ridge, TN, United States
| | - K. Dunham
- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, Durham, NC, United States
- National Student Services Contractor, Oak Ridge Associated Universities, Oak Ridge, TN, United States
| | - S. E. Davidson-Fritz
- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, Durham, NC, United States
| | - K. E. Carstens
- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, Durham, NC, United States
| | - J. Brown
- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, Durham, NC, United States
| | - R. S. Judson
- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, Durham, NC, United States
| | - K. Paul Friedman
- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, Durham, NC, United States
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de Leeuw VC, van Oostrom CTM, Wackers PFK, Pennings JLA, Hodemaekers HM, Piersma AH, Hessel EVS. Neuronal differentiation pathways and compound-induced developmental neurotoxicity in the human neural progenitor cell test (hNPT) revealed by RNA-seq. CHEMOSPHERE 2022; 304:135298. [PMID: 35700809 PMCID: PMC9247748 DOI: 10.1016/j.chemosphere.2022.135298] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 05/30/2022] [Accepted: 06/08/2022] [Indexed: 05/27/2023]
Abstract
There is an increased awareness that the use of animals for compound-induced developmental neurotoxicity (DNT) testing has limitations. Animal-free innovations, especially the ones based on human stem cell-based models are pivotal in studying DNT since they can mimic processes relevant to human brain development. Here we present the human neural progenitor test (hNPT), a 10-day protocol in which neural progenitor cells differentiate into a neuron-astrocyte co-culture. The study aimed to characterise differentiation over time and to find neurodevelopmental processes sensitive to compound exposure using transcriptomics. 3992 genes regulated in unexposed control cultures (p ≤ 0.001, log2FC ≥ 1) showed Gene Ontology (GO-) term enrichment for neuronal and glial differentiation, neurite extension, synaptogenesis, and synaptic transmission. Exposure to known or suspected DNT compounds (acrylamide, chlorpyrifos, fluoxetine, methyl mercury, or valproic acid) at concentrations resulting in 95% cell viability each regulated unique combinations of GO-terms relating to neural progenitor proliferation, neuronal and glial differentiation, axon development, synaptogenesis, synaptic transmission, and apoptosis. Investigation of the GO-terms 'neuron apoptotic process' and 'axon development' revealed common genes that were responsive across compounds, and might be used as biomarkers for DNT. The GO-term 'synaptic signalling', on the contrary, whilst also responsive to all compounds tested, showed little overlap in gene expression regulation patterns between the conditions. This GO-term may articulate compound-specific effects that may be relevant for revealing differences in mechanism of toxicity. Given its focus on neural progenitor cell to mature multilineage neuronal cell maturation and its detailed molecular readout based on gene expression analysis, hNPT might have added value as a tool for neurodevelopmental toxicity testing in vitro. Further assessment of DNT-specific biomarkers that represent these processes needs further studies.
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Affiliation(s)
- Victoria C de Leeuw
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands; Institute for Risk Assessment Sciences (IRAS), Utrecht University, Utrecht, the Netherlands.
| | - Conny T M van Oostrom
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
| | - Paul F K Wackers
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
| | - Jeroen L A Pennings
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
| | - Hennie M Hodemaekers
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
| | - Aldert H Piersma
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands; Institute for Risk Assessment Sciences (IRAS), Utrecht University, Utrecht, the Netherlands
| | - Ellen V S Hessel
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
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9
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Stucki AO, Barton-Maclaren TS, Bhuller Y, Henriquez JE, Henry TR, Hirn C, Miller-Holt J, Nagy EG, Perron MM, Ratzlaff DE, Stedeford TJ, Clippinger AJ. Use of new approach methodologies (NAMs) to meet regulatory requirements for the assessment of industrial chemicals and pesticides for effects on human health. FRONTIERS IN TOXICOLOGY 2022; 4:964553. [PMID: 36119357 PMCID: PMC9475191 DOI: 10.3389/ftox.2022.964553] [Citation(s) in RCA: 64] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 07/28/2022] [Indexed: 11/13/2022] Open
Abstract
New approach methodologies (NAMs) are increasingly being used for regulatory decision making by agencies worldwide because of their potential to reliably and efficiently produce information that is fit for purpose while reducing animal use. This article summarizes the ability to use NAMs for the assessment of human health effects of industrial chemicals and pesticides within the United States, Canada, and European Union regulatory frameworks. While all regulations include some flexibility to allow for the use of NAMs, the implementation of this flexibility varies across product type and regulatory scheme. This article provides an overview of various agencies’ guidelines and strategic plans on the use of NAMs, and specific examples of the successful application of NAMs to meet regulatory requirements. It also summarizes intra- and inter-agency collaborations that strengthen scientific, regulatory, and public confidence in NAMs, thereby fostering their global use as reliable and relevant tools for toxicological evaluations. Ultimately, understanding the current regulatory landscape helps inform the scientific community on the steps needed to further advance timely uptake of approaches that best protect human health and the environment.
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Affiliation(s)
- Andreas O. Stucki
- PETA Science Consortium International e.V., Stuttgart, Germany
- *Correspondence: Andreas O. Stucki,
| | - Tara S. Barton-Maclaren
- Safe Environments Directorate, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, Canada
| | - Yadvinder Bhuller
- Pest Management Regulatory Agency, Health Canada, Ottawa, ON, Canada
| | | | - Tala R. Henry
- Office of Pollution Prevention and Toxics, US Environmental Protection Agency, Washington, DC, United States
| | - Carole Hirn
- Scientific and Regulatory Affairs, JT International SA, Geneva, Switzerland
| | | | - Edith G. Nagy
- Bergeson & Campbell PC, Washington, DC, United States
| | - Monique M. Perron
- Office of Pesticide Programs, US Environmental Protection Agency, Washington, DC, United States
| | - Deborah E. Ratzlaff
- Safe Environments Directorate, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, Canada
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van der Zalm AJ, Barroso J, Browne P, Casey W, Gordon J, Henry TR, Kleinstreuer NC, Lowit AB, Perron M, Clippinger AJ. A framework for establishing scientific confidence in new approach methodologies. Arch Toxicol 2022; 96:2865-2879. [PMID: 35987941 PMCID: PMC9525335 DOI: 10.1007/s00204-022-03365-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 08/11/2022] [Indexed: 12/28/2022]
Abstract
Robust and efficient processes are needed to establish scientific confidence in new approach methodologies (NAMs) if they are to be considered for regulatory applications. NAMs need to be fit for purpose, reliable and, for the assessment of human health effects, provide information relevant to human biology. They must also be independently reviewed and transparently communicated. Ideally, NAM developers should communicate with stakeholders such as regulators and industry to identify the question(s), and specified purpose that the NAM is intended to address, and the context in which it will be used. Assessment of the biological relevance of the NAM should focus on its alignment with human biology, mechanistic understanding, and ability to provide information that leads to health protective decisions, rather than solely comparing NAM-based chemical testing results with those from traditional animal test methods. However, when NAM results are compared to historical animal test results, the variability observed within animal test method results should be used to inform performance benchmarks. Building on previous efforts, this paper proposes a framework comprising five essential elements to establish scientific confidence in NAMs for regulatory use: fitness for purpose, human biological relevance, technical characterization, data integrity and transparency, and independent review. Universal uptake of this framework would facilitate the timely development and use of NAMs by the international community. While this paper focuses on NAMs for assessing human health effects of pesticides and industrial chemicals, many of the suggested elements are expected to apply to other types of chemicals and to ecotoxicological effect assessments.
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Affiliation(s)
| | - João Barroso
- European Commission, Joint Research Centre (JRC), Ispra, Italy
| | - Patience Browne
- Organisation for Economic Co-Operation and Development, Hazard Assessment and Pesticides Programmes, Environmental Directorate, Paris, France
| | - Warren Casey
- National Institutes of Health, Division of the National Toxicology Program, National Institutes of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - John Gordon
- U.S. Consumer Product Safety Commission, Directorate for Health Sciences, Rockville, MD, USA
| | - Tala R Henry
- U.S. Environmental Protection Agency, Office of Pollution Prevention and Toxics, Washington, DC, USA
| | - Nicole C Kleinstreuer
- National Toxicology Program Interagency Center for the Evaluation of Alternative Toxicological Methods, Research Triangle Park, NC, USA
| | - Anna B Lowit
- U.S. Environmental Protection Agency, Office of Pollution Prevention and Toxics, Washington, DC, USA
| | - Monique Perron
- U.S. Environmental Protection Agency, Office of Pesticide Programs, Washington, DC, USA
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