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Luconi M, Sogorb MA, Markert UR, Benfenati E, May T, Wolbank S, Roncaglioni A, Schmidt A, Straccia M, Tait S. Human-Based New Approach Methodologies in Developmental Toxicity Testing: A Step Ahead from the State of the Art with a Feto-Placental Organ-on-Chip Platform. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:15828. [PMID: 36497907 PMCID: PMC9737555 DOI: 10.3390/ijerph192315828] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 11/20/2022] [Accepted: 11/25/2022] [Indexed: 06/17/2023]
Abstract
Developmental toxicity testing urgently requires the implementation of human-relevant new approach methodologies (NAMs) that better recapitulate the peculiar nature of human physiology during pregnancy, especially the placenta and the maternal/fetal interface, which represent a key stage for human lifelong health. Fit-for-purpose NAMs for the placental-fetal interface are desirable to improve the biological knowledge of environmental exposure at the molecular level and to reduce the high cost, time and ethical impact of animal studies. This article reviews the state of the art on the available in vitro (placental, fetal and amniotic cell-based systems) and in silico NAMs of human relevance for developmental toxicity testing purposes; in addition, we considered available Adverse Outcome Pathways related to developmental toxicity. The OECD TG 414 for the identification and assessment of deleterious effects of prenatal exposure to chemicals on developing organisms will be discussed to delineate the regulatory context and to better debate what is missing and needed in the context of the Developmental Origins of Health and Disease hypothesis to significantly improve this sector. Starting from this analysis, the development of a novel human feto-placental organ-on-chip platform will be introduced as an innovative future alternative tool for developmental toxicity testing, considering possible implementation and validation strategies to overcome the limitation of the current animal studies and NAMs available in regulatory toxicology and in the biomedical field.
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Affiliation(s)
- Michaela Luconi
- Department of Experimental and Clinical Biomedical Sciences “Mario Serio”, University of Florence, Viale Pieraccini 6, 50139 Florence, Italy
- I.N.B.B. (Istituto Nazionale Biostrutture e Biosistemi), Viale Medaglie d’Oro 305, 00136 Rome, Italy
| | - Miguel A. Sogorb
- Instituto de Bioingeniería, Universidad Miguel Hernández de Elche, Avenida de la Universidad s/n, 03202 Elche, Spain
| | - Udo R. Markert
- Placenta Lab, Department of Obstetrics, University Hospital Jena, Am Klinikum 1, 07747 Jena, Germany
| | - Emilio Benfenati
- Department of Environmental Health Sciences, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, 20156 Milan, Italy
| | - Tobias May
- InSCREENeX GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany
| | - Susanne Wolbank
- Ludwig Boltzmann Institut for Traumatology, The Research Center in Cooperation with AUVA, Austrian Cluster for Tissue Regeneration, Donaueschingenstrasse 13, 1200 Vienna, Austria
| | - Alessandra Roncaglioni
- Department of Environmental Health Sciences, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, 20156 Milan, Italy
| | - Astrid Schmidt
- Placenta Lab, Department of Obstetrics, University Hospital Jena, Am Klinikum 1, 07747 Jena, Germany
| | - Marco Straccia
- FRESCI by Science&Strategy SL, C/Roure Monjo 33, Vacarisses, 08233 Barcelona, Spain
| | - Sabrina Tait
- Centre for Gender-Specific Medicine, Istituto Superiore di Sanità, 00161 Rome, Italy
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2
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Pierro JD, Ahir BK, Baker NC, Kleinstreuer NC, Xia M, Knudsen TB. Computational model for fetal skeletal defects potentially linked to disruption of retinoic acid signaling. Front Pharmacol 2022; 13:971296. [PMID: 36172177 PMCID: PMC9511990 DOI: 10.3389/fphar.2022.971296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 07/21/2022] [Indexed: 11/13/2022] Open
Abstract
All-trans retinoic acid (ATRA) gradients determine skeletal patterning morphogenesis and can be disrupted by diverse genetic or environmental factors during pregnancy, leading to fetal skeleton defects. Adverse Outcome Pathway (AOP) frameworks for ATRA metabolism, signaling, and homeostasis allow for the development of new approach methods (NAMs) for predictive toxicology with less reliance on animal testing. Here, a data-driven model was constructed to identify chemicals associated with both ATRA pathway bioactivity and prenatal skeletal defects. The phenotype data was culled from ToxRefDB prenatal developmental toxicity studies and produced a list of 363 ToxRefDB chemicals with altered skeletal observations. Defects were classified regionally as cranial, post-cranial axial, appendicular, and other (unspecified) features based on ToxRefDB descriptors. To build a multivariate statistical model, high-throughput screening bioactivity data from >8,070 chemicals in ToxCast/Tox21 across 10 in vitro assays relevant to the retinoid signaling system were evaluated and compared to literature-based candidate reference chemicals in the dataset. There were 48 chemicals identified for effects on both in vivo skeletal defects and in vitro ATRA pathway targets for computational modeling. The list included 28 chemicals with prior evidence of skeletal defects linked to retinoid toxicity and 20 chemicals without prior evidence. The combination of thoracic cage defects and DR5 (direct repeats of 5 nucleotides for RAR/RXR transactivation) disruption was the most frequently occurring phenotypic and target disturbance, respectively. This data model provides valuable AOP elucidation and validates current mechanistic understanding. These findings also shed light on potential avenues for new mechanistic discoveries related to ATRA pathway disruption and associated skeletal dysmorphogenesis due to environmental exposures.
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Affiliation(s)
- Jocylin D. Pierro
- Center for Computational Toxicology and Exposure (CCTE), Computational Toxicology and Bioinformatics Branch (CTBB), Office of Research and Development (ORD), U.S. Environmental Protection Agency (USEPA), Research Triangle Park, NC, United States
| | - Bhavesh K. Ahir
- Eurofins Medical Device Testing, Lancaster, PA, United States
| | - Nancy C. Baker
- Scientific Computing and Data Curation Division (SCDCD), Leidos Contractor, Center for Computational Toxicology and Exposure (CCTE), USEPA/ORD, Research Triangle Park, NC, United States
| | - Nicole C. Kleinstreuer
- Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM), National Toxicology Program, National Institutes of Health, Research Triangle Park, NC, United States
| | - Menghang Xia
- Division for Pre-Clinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD, United States
| | - Thomas B. Knudsen
- Center for Computational Toxicology and Exposure (CCTE), Computational Toxicology and Bioinformatics Branch (CTBB), Office of Research and Development (ORD), U.S. Environmental Protection Agency (USEPA), Research Triangle Park, NC, United States
- *Correspondence: Thomas B. Knudsen, , orcid.org/0000-0002-5036-596x
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Daston GP, Mahony C, Thomas RS, Vinken M. Assessing Safety without Animal Testing: The Road Ahead. Toxicol Sci 2022; 187:214-218. [PMID: 35357465 DOI: 10.1093/toxsci/kfac039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
| | | | - Russell S Thomas
- US Environmental Protection Agency, Research Triangle Park, NC, USA
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Using adverse outcome pathways to contextualise (Q)SAR predictions for reproductive toxicity – A case study with aromatase inhibition. Reprod Toxicol 2022; 108:43-55. [DOI: 10.1016/j.reprotox.2022.01.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 01/14/2022] [Accepted: 01/21/2022] [Indexed: 12/22/2022]
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5
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Bayesian calibration of a stochastic, multiscale agent-based model for predicting in vitro tumor growth. PLoS Comput Biol 2021; 17:e1008845. [PMID: 34843457 PMCID: PMC8659698 DOI: 10.1371/journal.pcbi.1008845] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 12/09/2021] [Accepted: 11/02/2021] [Indexed: 12/31/2022] Open
Abstract
Hybrid multiscale agent-based models (ABMs) are unique in their ability to simulate individual cell interactions and microenvironmental dynamics. Unfortunately, the high computational cost of modeling individual cells, the inherent stochasticity of cell dynamics, and numerous model parameters are fundamental limitations of applying such models to predict tumor dynamics. To overcome these challenges, we have developed a coarse-grained two-scale ABM (cgABM) with a reduced parameter space that allows for an accurate and efficient calibration using a set of time-resolved microscopy measurements of cancer cells grown with different initial conditions. The multiscale model consists of a reaction-diffusion type model capturing the spatio-temporal evolution of glucose and growth factors in the tumor microenvironment (at tissue scale), coupled with a lattice-free ABM to simulate individual cell dynamics (at cellular scale). The experimental data consists of BT474 human breast carcinoma cells initialized with different glucose concentrations and tumor cell confluences. The confluence of live and dead cells was measured every three hours over four days. Given this model, we perform a time-dependent global sensitivity analysis to identify the relative importance of the model parameters. The subsequent cgABM is calibrated within a Bayesian framework to the experimental data to estimate model parameters, which are then used to predict the temporal evolution of the living and dead cell populations. To this end, a moment-based Bayesian inference is proposed to account for the stochasticity of the cgABM while quantifying uncertainties due to limited temporal observational data. The cgABM reduces the computational time of ABM simulations by 93% to 97% while staying within a 3% difference in prediction compared to ABM. Additionally, the cgABM can reliably predict the temporal evolution of breast cancer cells observed by the microscopy data with an average error and standard deviation for live and dead cells being 7.61±2.01 and 5.78±1.13, respectively. The calibration of agent-based models of tumor cell growth to experimental data remains a challenge in computational oncology. Besides the computational cost of modeling thousands of agents, the model’s intrinsic stochasticity demands numerous realizations of the simulations to accurately represent the statistical features of the model predictions. We developed a hybrid, multiscale, coarse-grain, agent-based model that captures the growth and decline of human breast carcinoma cells under different initial conditions. We determined the effects of coarse-graining the ABM on the multiscale model output and the number of repetitions necessary to capture the stochastic transitions present in the model. We identified the most influential parameters on the model prediction through a sensitivity analysis and selected which parameters can be fixed and which ones should be calibrated. Using Bayesian calibration, we show that the model can accurately represent the experimental data. The validation step indicates that our model can reliably predict the in vitro temporal data, depending on the choice of the training (calibration data) sets.
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6
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Bägli DJ. An Imperative for Discovery Advances in Congenital Anomalies of the External Genitalia. Urology 2021; 161:1-3. [PMID: 34843747 DOI: 10.1016/j.urology.2021.11.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 11/13/2021] [Indexed: 11/19/2022]
Affiliation(s)
- Darius J Bägli
- Departments of Surgery (Urology) & Physiology, University of Toronto, and The Hospital For Sick Children & Research Institute, Divisions of Urology & Developmental and Stem cell Biology, Toronto, Ontario, Canada..
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Knudsen TB, Fitzpatrick SC, De Abrew KN, Birnbaum LS, Chappelle A, Daston GP, Dolinoy DC, Elder A, Euling S, Faustman EM, Fedinick KP, Franzosa JA, Haggard DE, Haws L, Kleinstreuer NC, Buck Louis GM, Mendrick DL, Rudel R, Saili KS, Schug TT, Tanguay RL, Turley AE, Wetmore BA, White KW, Zurlinden TJ. FutureTox IV Workshop Summary: Predictive Toxicology for Healthy Children. Toxicol Sci 2021; 180:198-211. [PMID: 33555348 PMCID: PMC8041457 DOI: 10.1093/toxsci/kfab013] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
FutureTox IV, a Society of Toxicology Contemporary Concepts in Toxicology workshop, was held in November 2018. Building upon FutureTox I, II, and III, this conference focused on the latest science and technology for in vitro profiling and in silico modeling as it relates to predictive developmental and reproductive toxicity (DART). Publicly available high-throughput screening data sets are now available for broad in vitro profiling of bioactivities across large inventories of chemicals. Coupling this vast amount of mechanistic data with a deeper understanding of molecular embryology and post-natal development lays the groundwork for using new approach methodologies (NAMs) to evaluate chemical toxicity, drug efficacy, and safety assessment for embryo-fetal development. NAM is a term recently adopted in reference to any technology, methodology, approach, or combination thereof that can be used to provide information on chemical hazard and risk assessment to avoid the use of intact animals (U.S. Environmental Protection Agency [EPA], Strategic plan to promote the development and implementation of alternative test methods within the tsca program, 2018, https://www.epa.gov/sites/production/files/2018-06/documents/epa_alt_strat_plan_6-20-18_clean_final.pdf). There are challenges to implementing NAMs to evaluate chemicals for developmental toxicity compared with adult toxicity. This forum article reviews the 2018 workshop activities, highlighting challenges and opportunities for applying NAMs for adverse pregnancy outcomes (eg, preterm labor, malformations, low birth weight) as well as disorders manifesting postnatally (eg, neurodevelopmental impairment, breast cancer, cardiovascular disease, fertility). DART is an important concern for different regulatory statutes and test guidelines. Leveraging advancements in such approaches and the accompanying efficiencies to detecting potential hazards to human development are the unifying concepts toward implementing NAMs in DART testing. Although use of NAMs for higher level regulatory decision making is still on the horizon, the conference highlighted novel testing platforms and computational models that cover multiple levels of biological organization, with the unique temporal dynamics of embryonic development, and novel approaches for estimating toxicokinetic parameters essential in supporting in vitro to in vivo extrapolation.
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Affiliation(s)
- Thomas B Knudsen
- U.S. Environmental Protection Agency, ORD, Research Triangle Park, North Carolina, USA
| | | | | | - Linda S Birnbaum
- National Institute of Environmental Health Science, NIH, Research Triangle Park, North Carolina, USA
| | - Anne Chappelle
- Chappelle Toxicology Consulting, LLC, Chadds Ford, Pennsylvania, USA
| | | | | | - Alison Elder
- University of Rochester, Rochester, New York, USA
| | - Susan Euling
- U.S. Environmental Protection Agency, Office of Children’s Health Protection, Washington, District of Columbia, USA
| | | | | | - Jill A Franzosa
- U.S. Environmental Protection Agency, ORD, Research Triangle Park, North Carolina, USA
| | - Derik E Haggard
- U.S. Environmental Protection Agency, ORD, Research Triangle Park, North Carolina, USA
- Oak Ridge Institute for Science and Education (ORISE);, Texas, USA
| | | | | | | | - Donna L Mendrick
- U.S. Food and Drug Administration, NCTR, Silver Spring, Maryland, USA
| | | | - Katerine S Saili
- U.S. Environmental Protection Agency, ORD, Research Triangle Park, North Carolina, USA
| | - Thaddeus T Schug
- National Institute of Environmental Health Science, NIH, Research Triangle Park, North Carolina, USA
| | | | | | - Barbara A Wetmore
- U.S. Environmental Protection Agency, ORD, Research Triangle Park, North Carolina, USA
| | - Kimberly W White
- American Chemistry Council, Washington, District of Columbia, USA
| | - Todd J Zurlinden
- U.S. Environmental Protection Agency, ORD, Research Triangle Park, North Carolina, USA
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8
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Stadler HS, Peters CA, Sturm RM, Baker LA, Best CJM, Bird VY, Geller F, Hoshizaki DK, Knudsen TB, Norton JM, Romao RLP, Cohn MJ. Meeting report on the NIDDK/AUA Workshop on Congenital Anomalies of External Genitalia: challenges and opportunities for translational research. J Pediatr Urol 2020; 16:791-804. [PMID: 33097421 PMCID: PMC7885182 DOI: 10.1016/j.jpurol.2020.09.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 09/10/2020] [Accepted: 09/13/2020] [Indexed: 01/02/2023]
Abstract
Congenital anomalies of the external genitalia (CAEG) are a prevalent and serious public health concern with lifelong impacts on the urinary function, sexual health, fertility, tumor development, and psychosocial wellbeing of affected individuals. Complications of treatment are frequent, and data reflecting long-term outcomes in adulthood are limited. To identify a path forward to improve treatments and realize the possibility of preventing CAEG, the National Institute of Diabetes and Digestive and Kidney Diseases and the American Urological Association convened researchers from a range of disciplines to coordinate research efforts to fully understand the different etiologies of these common conditions, subsequent variation in clinical phenotypes, and best practices for long term surgical success. Meeting participants concluded that a central data hub for clinical evaluations, including collection of DNA samples from patients and their parents, and short interviews to determine familial penetrance (small pedigrees), would accelerate research in this field. Such a centralized datahub will advance efforts to develop detailed multi-dimensional phenotyping and will enable access to genome sequence analyses and associated metadata to define the genetic bases for these conditions. Inclusion of tissue samples and integration of clinical studies with basic research using human cells and animal models will advance efforts to identify the developmental mechanisms that are disrupted during development and will add cellular and molecular granularity to phenotyping CAEG. While the discussion focuses heavily on hypospadias, this can be seen as a potential template for other conditions in the realm of CAEG, including cryptorchidism or the exstrophy-epispadias complex. Taken together with long-term clinical follow-up, these data could inform surgical choices and improve likelihood for long-term success.
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Affiliation(s)
- H Scott Stadler
- Department of Skeletal Biology, Shriners Hospital for Children, 3101 SW Sam Jackson Park Road, Portland, OR, Oregon Health & Science University, Department of Orthopaedics and Rehabilitation, Portland, 97239, OR, USA.
| | - Craig A Peters
- Department of Urology, University of Texas Southwestern, 5323 Harry Hines Blvd., Dallas, 75390-9110, TX, USA; Pediatric Urology, Children's Health System Texas, University of Texas Southwestern, Dallas, 75390, TX, USA.
| | - Renea M Sturm
- Department of Urology, Division of Pediatric Urology, University of California Los Angeles, 200 Medical Plaza #170, Los Angeles, 90095, CA, USA
| | - Linda A Baker
- Department of Urology, University of Texas Southwestern, 5323 Harry Hines Blvd., Dallas, 75390-9110, TX, USA
| | - Carolyn J M Best
- American Urological Association, 1000 Corporate Boulevard, Linthicum, 21090, MD, USA
| | - Victoria Y Bird
- Department of Urology, University of Florida, Gainesville, 32610, FL, USA; National Medical Association and Research Group, 5745 SW 75th Street, #507, Gainesville, 32608, FL, USA
| | - Frank Geller
- Department of Epidemiology Research, Statens Serum Institut, 5 Artillerivej, Copenhagen S, DK-2300, Denmark
| | - Deborah K Hoshizaki
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 6707 Democracy Boulevard, Bethesda, 20892, MD, USA
| | - Thomas B Knudsen
- US Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Research Triangle Park, 27711, NC, USA
| | - Jenna M Norton
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 6707 Democracy Boulevard, Bethesda, 20892, MD, USA
| | - Rodrigo L P Romao
- Departments of Surgery and Urology, IWK Health Centre, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Martin J Cohn
- Department of Molecular Genetics and Microbiology, Department of Biology, And UF Genetics Institute, University of Florida, PO Box 103610, Gainesville, 32610, FL, USA.
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9
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Knudsen TB, Spencer RM, Pierro JD, Baker NC. Computational Biology and in silico Toxicodynamics. CURRENT OPINION IN TOXICOLOGY 2020; 23-24:119-126. [PMID: 36561131 PMCID: PMC9770085 DOI: 10.1016/j.cotox.2020.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
New approach methodologies (NAMs) refer to any non-animal technology, methodology, approach, or combination thereof that can be used to provide information on chemical hazard and risk assessment that avoids the use of intact animals. A spectrum of in silico models is needed for the integrated analysis of various domains in toxicology to improve predictivity and reduce animal testing. This review focuses on in silico approaches, computer models, and computational intelligence for developmental and reproductive toxicity (predictive DART), providing a means to measure toxicodynamics in simulated systems for quantitative prediction of adverse outcomes phenotypes.
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Affiliation(s)
- Thomas B. Knudsen
- Center for Computational Toxicology and Exposure (CCTE), Biomolecular and Computational Toxicology Division (BCTD), Computational Toxicology and Bioinformatics Branch (CTBB), Office of Research and Development (ORD), U.S. Environmental Protection Agency (USEPA), Research Triangle Park NC 27711,Corresponding author:
| | - Richard M. Spencer
- General Dynamics, Contractor, Environmental Modeling and Visualization Laboratory (EMVL), US EPA/ORD, Research Triangle Park NC 27711
| | - Jocylin D. Pierro
- Center for Computational Toxicology and Exposure (CCTE), Biomolecular and Computational Toxicology Division (BCTD), Computational Toxicology and Bioinformatics Branch (CTBB), Office of Research and Development (ORD), U.S. Environmental Protection Agency (USEPA), Research Triangle Park NC 27711
| | - Nancy C. Baker
- Leidos Contractor, Center for Computational Toxicology and Exposure (CCTE), Scientific Computing and Data Curation Division (SCDCD), USEPA/ORD, Research Triangle Park NC 27711
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10
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de Leeuw VC, van Nieuwland M, Bokkers BGH, Piersma AH. Culture Conditions Affect Chemical-Induced Developmental Toxicity In Vitro: The Case of Folic Acid, Methionine and Methotrexate in the Neural Embryonic Stem Cell Test. Altern Lab Anim 2020; 48:173-183. [PMID: 33034509 DOI: 10.1177/0261192920961963] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In vitro tests are increasingly applied in chemical hazard assessment. Basic culture conditions may affect the outcome of in vitro tests and should be optimised to reduce false predictions. The neural embryonic stem cell test (ESTn) can predict early neurodevelopmental effects of chemicals, as it mimics the differentiation of stem cells towards the neuroectodermal lineage. Normal early neural differentiation depends crucially on folic acid (FA) and methionine (MET), both elements of the one-carbon (1C) cycle. The aim of this study was to assess the concentration-dependent influence of FA and MET on neural differentiation in the ESTn, and its consequences for assay sensitivity to methotrexate (MTX), a compound that interferes with the 1C cycle. Neural differentiation was inhibited below 0.007 mM and above 0.22 mM FA, while both stem cell viability (< 0.097 mM, > 1.52 mM) and neural differentiation (< 0.181 mM, > 1.35 mM) were affected when changing MET concentrations. A 10-day exposure to 13 nM MTX inhibited neural differentiation, especially in FA- and MET-deficient conditions. However, a 24-hour exposure to 39 nM MTX decreased neural cell and neural crest cell differentiation markers only when the concentration of FA in the medium was three times the standard concentration, which was expected to have a protective effect against MTX. These results show the importance of nutrient concentrations, exposure scenarios and timing of read-outs for cell differentiation and compound sensitivity in the ESTn. Caution should be taken when interpreting results from a single in vitro test, especially when extrapolating to effects on complex morphogenetic processes, like neural tube development.
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Affiliation(s)
- Victoria C de Leeuw
- Centre for Health Protection, National Institute for Public Health and the Environment (10206RIVM), Bilthoven, the Netherlands.,Institute for Risk Assessment Sciences (IRAS), Utrecht University, Utrecht, the Netherlands
| | - Marieke van Nieuwland
- Centre for Health Protection, National Institute for Public Health and the Environment (10206RIVM), Bilthoven, the Netherlands.,Radboudumc, Medical Faculty, Nijmegen, the Netherlands
| | - Bas G H Bokkers
- Centre for Health Protection, National Institute for Public Health and the Environment (10206RIVM), Bilthoven, the Netherlands.,Centre for Safety of Substances and Products, National Institute for Public Health and the Environment (10206RIVM), Bilthoven, the Netherlands
| | - Aldert H Piersma
- Centre for Health Protection, National Institute for Public Health and the Environment (10206RIVM), Bilthoven, the Netherlands.,Institute for Risk Assessment Sciences (IRAS), Utrecht University, Utrecht, the Netherlands
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11
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Heusinkveld HJ, Staal YCM, Baker NC, Daston G, Knudsen TB, Piersma A. An ontology for developmental processes and toxicities of neural tube closure. Reprod Toxicol 2020; 99:160-167. [PMID: 32926990 PMCID: PMC10083840 DOI: 10.1016/j.reprotox.2020.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/12/2020] [Accepted: 09/08/2020] [Indexed: 02/07/2023]
Abstract
In recent years, the development and implementation of animal-free approaches to chemical and pharmaceutical hazard and risk assessment has taken off. Alternative approaches are being developed starting from the perspective of human biology and physiology. Neural tube closure is a vital step that occurs early in human development. Correct closure of the neural tube depends on a complex interplay between proteins along a number of protein concentration gradients. The sensitivity of neural tube closure to chemical disturbance of signalling pathways such as the retinoid pathway, is well known. To map the pathways underlying neural tube closure, literature data on the molecular regulation of neural tube closure were collected. As the process of neural tube closure is highly conserved in vertebrates, the extensive literature available for the mouse was used whilst considering its relevance for humans. Thus, important cell compartments, regulatory pathways, and protein interactions essential for neural tube closure under physiological circumstances were identified and mapped. An understanding of aberrant processes leading to neural tube defects (NTDs) requires detailed maps of neural tube embryology, including the complex genetic signals and responses underlying critical cellular dynamical and biomechanical processes. The retinoid signaling pathway serves as a case study for this ontology because of well-defined crosstalk with the genetic control of neural tube patterning and morphogenesis. It is a known target for mechanistically-diverse chemical structures that disrupt neural tube closure The data presented in this manuscript will set the stage for constructing mathematical models and computer simulation of neural tube closure for human-relevant AOPs and predictive toxicology.
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Affiliation(s)
- Harm J Heusinkveld
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands.
| | - Yvonne C M Staal
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
| | | | - George Daston
- Global Product Stewardship, The Procter & Gamble Company, Cincinnati, OH USA
| | - Thomas B Knudsen
- Center for Computational Toxicology and Exposure, U.S. Environmental Protection Agency, Research Triangle Park NC 27711, USA
| | - Aldert Piersma
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
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12
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Carlson LM, Champagne FA, Cory-Slechta DA, Dishaw L, Faustman E, Mundy W, Segal D, Sobin C, Starkey C, Taylor M, Makris SL, Kraft A. Potential frameworks to support evaluation of mechanistic data for developmental neurotoxicity outcomes: A symposium report. Neurotoxicol Teratol 2020; 78:106865. [PMID: 32068112 PMCID: PMC7160758 DOI: 10.1016/j.ntt.2020.106865] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 02/05/2020] [Accepted: 02/10/2020] [Indexed: 12/16/2022]
Abstract
A key challenge in systematically incorporating mechanistic data into human health assessments is that, compared to studies of apical health endpoints, these data are both more abundant (mechanistic studies routinely outnumber other studies by several orders of magnitude) and more heterogeneous (e.g. different species, test system, tissue, cell type, exposure paradigm, or specific assays performed). A structured decision-making process for organizing, integrating, and weighing mechanistic DNT data for use in human health risk assessments will improve the consistency and efficiency of such evaluations. At the Developmental Neurotoxicology Society (DNTS) 2016 annual meeting, a symposium was held to address the application of existing organizing principles and frameworks for evaluation of mechanistic data relevant to interpreting neurotoxicology data. Speakers identified considerations with potential to advance the use of mechanistic DNT data in risk assessment, including considering the context of each exposure, since epigenetics, tissue type, sex, stress, nutrition and other factors can modify toxicity responses in organisms. It was also suggested that, because behavior is a manifestation of complex nervous system function, the presence and absence of behavioral change itself could be used to organize the interpretation of multiple complex simultaneous mechanistic changes. Several challenges were identified with frameworks and their implementation, and ongoing research to develop these approaches represents an early step toward full evaluation of mechanistic DNT data for assessments.
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Affiliation(s)
- Laura M Carlson
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, RTP, NC.
| | | | - Deborah A Cory-Slechta
- Department of Environmental Medicine, University of Rochester Medical School Rochester, NY
| | - Laura Dishaw
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, RTP, NC
| | - Elaine Faustman
- School of Public Health, Institute for Risk Analysis and Risk Communication, University of Washington, Seattle, WA
| | - William Mundy
- Neurotoxicologist, Durham, NC (formerly National Health and Environmental Effects Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, RTP, NC))
| | - Deborah Segal
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC
| | - Christina Sobin
- Dept of Public Health Sciences, The University of Texas at El Paso, El Paso, Texas, USA
| | - Carol Starkey
- Booz Allen Hamilton (formerly research fellow with the Oak Ridge Institute for Science and Engineering (ORISE) with Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington DC))
| | - Michele Taylor
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, RTP, NC
| | - Susan L Makris
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC
| | - Andrew Kraft
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC; Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, RTP, NC
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13
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Clements JM, Hawkes RG, Jones D, Adjei A, Chambers T, Simon L, Stemplewski H, Berry N, Price S, Pirmohamed M, Piersma AH, Waxenecker G, Barrow P, Beekhuijzen MEW, Fowkes A, Prior H, Sewell F. Predicting the safety of medicines in pregnancy: A workshop report. Reprod Toxicol 2020; 93:199-210. [PMID: 32126282 DOI: 10.1016/j.reprotox.2020.02.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 02/10/2020] [Accepted: 02/26/2020] [Indexed: 01/05/2023]
Abstract
The framework for developmental toxicity testing has remained largely unchanged for over 50 years and although it remains invaluable in assessing potential risks in pregnancy, knowledge gaps exist, and some outcomes do not necessarily correlate with clinical experience. Advances in omics, in silico approaches and alternative assays are providing opportunities to enhance our understanding of embryo-fetal development and the prediction of potential risks associated with the use of medicines in pregnancy. A workshop organised by the Medicines and Healthcare products Regulatory Agency (MHRA), "Predicting the Safety of Medicines in Pregnancy - a New Era?", was attended by delegates representing regulatory authorities, academia, industry, patients, funding bodies and software developers to consider how to improve the quality of and access to nonclinical developmental toxicity data and how to use this data to better predict the safety of medicines in human pregnancy. The workshop delegates concluded that based on comparative data to date alternative methodologies are currently no more predictive than conventional methods and not qualified for use in regulatory submissions. To advance the development and qualification of alternative methodologies, there is a requirement for better coordinated multidisciplinary cross-sector interactions coupled with data sharing. Furthermore, a better understanding of human developmental biology and the incorporation of this knowledge into the development of alternative methodologies is essential to enhance the prediction of adverse outcomes for human development. The output of the workshop was a series of recommendations aimed at supporting multidisciplinary efforts to develop and validate these alternative methodologies.
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Affiliation(s)
- J M Clements
- Medicines and Healthcare products Regulatory Agency, London, UK
| | - R G Hawkes
- Medicines and Healthcare products Regulatory Agency, London, UK.
| | - D Jones
- Medicines and Healthcare products Regulatory Agency, London, UK
| | - A Adjei
- Medicines and Healthcare products Regulatory Agency, London, UK
| | - T Chambers
- Medicines and Healthcare products Regulatory Agency, London, UK
| | - L Simon
- Medicines and Healthcare products Regulatory Agency, London, UK
| | - H Stemplewski
- Medicines and Healthcare products Regulatory Agency, London, UK
| | - N Berry
- National Institute for Biological Standards and Control, Potters Bar, UK
| | | | | | - A H Piersma
- National Institute for Public Health and the Environment (RIVM), Center for Health Protection, Bilthoven, Netherlands
| | - G Waxenecker
- Austrian Medicines and Medical Devices Agency, Vienna, Austria
| | - P Barrow
- Roche Pharmaceutical Research and Early Development, Basel, Switzerland
| | | | | | - H Prior
- National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs), London, UK
| | - F Sewell
- National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs), London, UK
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14
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Thomas RS, Bahadori T, Buckley TJ, Cowden J, Deisenroth C, Dionisio KL, Frithsen JB, Grulke CM, Gwinn MR, Harrill JA, Higuchi M, Houck KA, Hughes MF, Hunter ES, Isaacs KK, Judson RS, Knudsen TB, Lambert JC, Linnenbrink M, Martin TM, Newton SR, Padilla S, Patlewicz G, Paul-Friedman K, Phillips KA, Richard AM, Sams R, Shafer TJ, Setzer RW, Shah I, Simmons JE, Simmons SO, Singh A, Sobus JR, Strynar M, Swank A, Tornero-Valez R, Ulrich EM, Villeneuve DL, Wambaugh JF, Wetmore BA, Williams AJ. The Next Generation Blueprint of Computational Toxicology at the U.S. Environmental Protection Agency. Toxicol Sci 2019; 169:317-332. [PMID: 30835285 PMCID: PMC6542711 DOI: 10.1093/toxsci/kfz058] [Citation(s) in RCA: 211] [Impact Index Per Article: 42.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The U.S. Environmental Protection Agency (EPA) is faced with the challenge of efficiently and credibly evaluating chemical safety often with limited or no available toxicity data. The expanding number of chemicals found in commerce and the environment, coupled with time and resource requirements for traditional toxicity testing and exposure characterization, continue to underscore the need for new approaches. In 2005, EPA charted a new course to address this challenge by embracing computational toxicology (CompTox) and investing in the technologies and capabilities to push the field forward. The return on this investment has been demonstrated through results and applications across a range of human and environmental health problems, as well as initial application to regulatory decision-making within programs such as the EPA's Endocrine Disruptor Screening Program. The CompTox initiative at EPA is more than a decade old. This manuscript presents a blueprint to guide the strategic and operational direction over the next 5 years. The primary goal is to obtain broader acceptance of the CompTox approaches for application to higher tier regulatory decisions, such as chemical assessments. To achieve this goal, the blueprint expands and refines the use of high-throughput and computational modeling approaches to transform the components in chemical risk assessment, while systematically addressing key challenges that have hindered progress. In addition, the blueprint outlines additional investments in cross-cutting efforts to characterize uncertainty and variability, develop software and information technology tools, provide outreach and training, and establish scientific confidence for application to different public health and environmental regulatory decisions.
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Affiliation(s)
- Russell S. Thomas
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Tina Bahadori
- National Center for Environmental Assessment, Office of Research and Development, US Environmental Protection Agency
| | - Timothy J. Buckley
- National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - John Cowden
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Chad Deisenroth
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Kathie L. Dionisio
- National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - Jeffrey B. Frithsen
- Chemical Safety for Sustainability National Research Program, Office of Research and Development, US Environmental Protection Agency
| | - Christopher M. Grulke
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Maureen R. Gwinn
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Joshua A. Harrill
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Mark Higuchi
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - Keith A. Houck
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Michael F. Hughes
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - E. Sidney Hunter
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - Kristin K. Isaacs
- National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - Richard S. Judson
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Thomas B. Knudsen
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Jason C. Lambert
- National Center for Environmental Assessment, Office of Research and Development, US Environmental Protection Agency
| | - Monica Linnenbrink
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Todd M. Martin
- National Risk Management Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - Seth R. Newton
- National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - Stephanie Padilla
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - Grace Patlewicz
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Katie Paul-Friedman
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Katherine A. Phillips
- National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - Ann M. Richard
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Reeder Sams
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Timothy J. Shafer
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - R. Woodrow Setzer
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Imran Shah
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Jane E. Simmons
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - Steven O. Simmons
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Amar Singh
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Jon R. Sobus
- National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - Mark Strynar
- National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - Adam Swank
- National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - Rogelio Tornero-Valez
- National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - Elin M. Ulrich
- National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - Daniel L Villeneuve
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - John F. Wambaugh
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
| | - Barbara A. Wetmore
- National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency
| | - Antony J. Williams
- National Center for Computational Toxicology, Office of Research and Development, US Environmental Protection Agency
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15
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Abstract
The complexity of morphogenesis poses a fundamental challenge to understanding the mechanisms governing the formation of biological patterns and structures. Over the past century, numerous processes have been identified as critically contributing to morphogenetic events, but the interplay between the various components and aspects of pattern formation have been much harder to grasp. The combination of traditional biology with mathematical and computational methods has had a profound effect on our current understanding of morphogenesis and led to significant insights and advancements in the field. In particular, the theoretical concepts of reaction–diffusion systems and positional information, proposed by Alan Turing and Lewis Wolpert, respectively, dramatically influenced our general view of morphogenesis, although typically in isolation from one another. In recent years, agent-based modeling has been emerging as a consolidation and implementation of the two theories within a single framework. Agent-based models (ABMs) are unique in their ability to integrate combinations of heterogeneous processes and investigate their respective dynamics, especially in the context of spatial phenomena. In this review, we highlight the benefits and technical challenges associated with ABMs as tools for examining morphogenetic events. These models display unparalleled flexibility for studying various morphogenetic phenomena at multiple levels and have the important advantage of informing future experimental work, including the targeted engineering of tissues and organs.
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16
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Zhang Q, Li J, Middleton A, Bhattacharya S, Conolly RB. Bridging the Data Gap From in vitro Toxicity Testing to Chemical Safety Assessment Through Computational Modeling. Front Public Health 2018; 6:261. [PMID: 30255008 PMCID: PMC6141783 DOI: 10.3389/fpubh.2018.00261] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 08/21/2018] [Indexed: 12/18/2022] Open
Abstract
Chemical toxicity testing is moving steadily toward a human cell and organoid-based in vitro approach for reasons including scientific relevancy, efficiency, cost, and ethical rightfulness. Inferring human health risk from chemical exposure based on in vitro testing data is a challenging task, facing various data gaps along the way. This review identifies these gaps and makes a case for the in silico approach of computational dose-response and extrapolation modeling to address many of the challenges. Mathematical models that can mechanistically describe chemical toxicokinetics (TK) and toxicodynamics (TD), for both in vitro and in vivo conditions, are the founding pieces in this regard. Identifying toxicity pathways and in vitro point of departure (PoD) associated with adverse health outcomes requires an understanding of the molecular key events in the interacting transcriptome, proteome, and metabolome. Such an understanding will in turn help determine the sets of sensitive biomarkers to be measured in vitro and the scope of toxicity pathways to be modeled in silico. In vitro data reporting both pathway perturbation and chemical biokinetics in the culture medium serve to calibrate the toxicity pathway and virtual tissue models, which can then help predict PoDs in response to chemical dosimetry experienced by cells in vivo. Two types of in vitro to in vivo extrapolation (IVIVE) are needed. (1) For toxic effects involving systemic regulations, such as endocrine disruption, organism-level adverse outcome pathway (AOP) models are needed to extrapolate in vitro toxicity pathway perturbation to in vivo PoD. (2) Physiologically-based toxicokinetic (PBTK) modeling is needed to extrapolate in vitro PoD dose metrics into external doses for expected exposure scenarios. Linked PBTK and TD models can explore the parameter space to recapitulate human population variability in response to chemical insults. While challenges remain for applying these modeling tools to support in vitro toxicity testing, they open the door toward population-stratified and personalized risk assessment.
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Affiliation(s)
- Qiang Zhang
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, United States
| | - Jin Li
- Unilever, Safety and Environmental Assurance Centre, Colworth Science Park, Sharnbrook, United Kingdom
| | - Alistair Middleton
- Unilever, Safety and Environmental Assurance Centre, Colworth Science Park, Sharnbrook, United Kingdom
| | - Sudin Bhattacharya
- Biomedical Engineering, Michigan State University, East Lansing, MI, United States
| | - Rory B Conolly
- Integrated Systems Toxicology Division, National Health and Environmental Effects Research Laboratory, United States Environmental Protection Agency, Durham, NC, United States
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17
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Saili KS, Zurlinden TJ, Schwab AJ, Silvin A, Baker NC, Hunter ES, Ginhoux F, Knudsen TB. Blood-brain barrier development: Systems modeling and predictive toxicology. Birth Defects Res 2018; 109:1680-1710. [PMID: 29251840 DOI: 10.1002/bdr2.1180] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 11/12/2017] [Indexed: 01/17/2023]
Abstract
The blood-brain barrier (BBB) serves as a gateway for passage of drugs, chemicals, nutrients, metabolites, and hormones between vascular and neural compartments in the brain. Here, we review BBB development with regard to the microphysiology of the neurovascular unit (NVU) and the impact of BBB disruption on brain development. Our focus is on modeling these complex systems. Extant in silico models are available as tools to predict the probability of drug/chemical passage across the BBB; in vitro platforms for high-throughput screening and high-content imaging provide novel data streams for profiling chemical-biological interactions; and engineered human cell-based microphysiological systems provide empirical models with which to investigate the dynamics of NVU function. Computational models are needed that bring together kinetic and dynamic aspects of NVU function across gestation and under various physiological and toxicological scenarios. This integration will inform adverse outcome pathways to reduce uncertainty in translating in vitro data and in silico models for use in risk assessments that aim to protect neurodevelopmental health.
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Affiliation(s)
- Katerine S Saili
- National Center for Computational Toxicology (NCCT); U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina 27711
| | - Todd J Zurlinden
- National Center for Computational Toxicology (NCCT); U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina 27711
| | - Andrew J Schwab
- National Health and Environmental Effects Research Laboratory (NHEERL), U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina 27711
| | - Aymeric Silvin
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), 138648, Singapore
| | - Nancy C Baker
- Leidos, contractor to NCCT, Research Triangle Park, North Carolina 27711
| | - E Sidney Hunter
- National Health and Environmental Effects Research Laboratory (NHEERL), U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina 27711
| | - Florent Ginhoux
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), 138648, Singapore
| | - Thomas B Knudsen
- National Center for Computational Toxicology (NCCT); U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina 27711
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18
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Piersma A, Burgdorf T, Louekari K, Desprez B, Taalman R, Landsiedel R, Barroso J, Rogiers V, Eskes C, Oelgeschläger M, Whelan M, Braeuning A, Vinggaard A, Kienhuis A, van Benthem J, Ezendam J. Workshop on acceleration of the validation and regulatory acceptance of alternative methods and implementation of testing strategies. Toxicol In Vitro 2018; 50:62-74. [DOI: 10.1016/j.tiv.2018.02.018] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 02/28/2018] [Accepted: 02/28/2018] [Indexed: 01/01/2023]
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19
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Hessel EVS, Staal YCM, Piersma AH. Design and validation of an ontology-driven animal-free testing strategy for developmental neurotoxicity testing. Toxicol Appl Pharmacol 2018; 354:136-152. [PMID: 29544899 DOI: 10.1016/j.taap.2018.03.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 02/26/2018] [Accepted: 03/11/2018] [Indexed: 12/26/2022]
Abstract
Developmental neurotoxicity entails one of the most complex areas in toxicology. Animal studies provide only limited information as to human relevance. A multitude of alternative models have been developed over the years, providing insights into mechanisms of action. We give an overview of fundamental processes in neural tube formation, brain development and neural specification, aiming at illustrating complexity rather than comprehensiveness. We also give a flavor of the wealth of alternative methods in this area. Given the impressive progress in mechanistic knowledge of human biology and toxicology, the time is right for a conceptual approach for designing testing strategies that cover the integral mechanistic landscape of developmental neurotoxicity. The ontology approach provides a framework for defining this landscape, upon which an integral in silico model for predicting toxicity can be built. It subsequently directs the selection of in vitro assays for rate-limiting events in the biological network, to feed parameter tuning in the model, leading to prediction of the toxicological outcome. Validation of such models requires primary attention to coverage of the biological domain, rather than classical predictive value of individual tests. Proofs of concept for such an approach are already available. The challenge is in mining modern biology, toxicology and chemical information to feed intelligent designs, which will define testing strategies for neurodevelopmental toxicity testing.
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Affiliation(s)
- Ellen V S Hessel
- Center for Health Protection, National Institute for Public Health and The Environment (RIVM), P.O. Box 1, 3720BA Bilthoven, The Netherlands.
| | - Yvonne C M Staal
- Center for Health Protection, National Institute for Public Health and The Environment (RIVM), P.O. Box 1, 3720BA Bilthoven, The Netherlands
| | - Aldert H Piersma
- Center for Health Protection, National Institute for Public Health and The Environment (RIVM), P.O. Box 1, 3720BA Bilthoven, The Netherlands; Institute for Risk Assessment Sciences (IRAS), Utrecht University, Utrecht, The Netherlands
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20
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Bal-Price A, Hogberg HT, Crofton KM, Daneshian M, FitzGerald RE, Fritsche E, Heinonen T, Hougaard Bennekou S, Klima S, Piersma AH, Sachana M, Shafer TJ, Terron A, Monnet-Tschudi F, Viviani B, Waldmann T, Westerink RHS, Wilks MF, Witters H, Zurich MG, Leist M. Recommendation on test readiness criteria for new approach methods in toxicology: Exemplified for developmental neurotoxicity. ALTEX-ALTERNATIVES TO ANIMAL EXPERIMENTATION 2018; 35:306-352. [PMID: 29485663 DOI: 10.14573/altex.1712081] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 01/29/2018] [Indexed: 01/06/2023]
Abstract
Multiple non-animal-based test methods have never been formally validated. In order to use such new approach methods (NAMs) in a regulatory context, criteria to define their readiness are necessary. The field of developmental neurotoxicity (DNT) testing is used to exemplify the application of readiness criteria. The costs and number of untested chemicals are overwhelming for in vivo DNT testing. Thus, there is a need for inexpensive, high-throughput NAMs, to obtain initial information on potential hazards, and to allow prioritization for further testing. A background on the regulatory and scientific status of DNT testing is provided showing different types of test readiness levels, depending on the intended use of data from NAMs. Readiness criteria, compiled during a stakeholder workshop, uniting scientists from academia, industry and regulatory authorities are presented. An important step beyond the listing of criteria, was the suggestion for a preliminary scoring scheme. On this basis a (semi)-quantitative analysis process was assembled on test readiness of 17 NAMs with respect to various uses (e.g. prioritization/screening, risk assessment). The scoring results suggest that several assays are currently at high readiness levels. Therefore, suggestions are made on how DNT NAMs may be assembled into an integrated approach to testing and assessment (IATA). In parallel, the testing state in these assays was compiled for more than 1000 compounds. Finally, a vision is presented on how further NAM development may be guided by knowledge of signaling pathways necessary for brain development, DNT pathophysiology, and relevant adverse outcome pathways (AOP).
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Affiliation(s)
- Anna Bal-Price
- European Commission, Joint Research Centre (EC JRC), Ispra (VA), Italy
| | - Helena T Hogberg
- Center for Alternatives to Animal Testing (CAAT), Johns Hopkins University, Baltimore, MD, USA
| | - Kevin M Crofton
- National Centre for Computational Toxicology, US EPA, RTP, Washington, NC, USA
| | - Mardas Daneshian
- Center for Alternatives to Animal Testing, CAAT-Europe, University of Konstanz, Konstanz, Germany
| | - Rex E FitzGerald
- Swiss Centre for Human Applied Toxicology, SCAHT, University of Basle, Switzerland
| | - Ellen Fritsche
- IUF - Leibniz Research Institute for Environmental Medicine & Heinrich-Heine-University, Düsseldorf, Germany
| | - Tuula Heinonen
- Finnish Centre for Alternative Methods (FICAM), University of Tampere, Tampere, Finland
| | | | - Stefanie Klima
- In vitro Toxicology and Biomedicine, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Aldert H Piersma
- RIVM, National Institute for Public Health and the Environment, Bilthoven, and Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
| | - Magdalini Sachana
- Organisation for Economic Co-operation and Development (OECD), Paris, France
| | - Timothy J Shafer
- National Centre for Computational Toxicology, US EPA, RTP, Washington, NC, USA
| | | | - Florianne Monnet-Tschudi
- Swiss Centre for Human Applied Toxicology, SCAHT, University of Basle, Switzerland.,Department of Physiology, University of Lausanne, Lausanne, Switzerland
| | - Barbara Viviani
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Italy
| | - Tanja Waldmann
- In vitro Toxicology and Biomedicine, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Remco H S Westerink
- Neurotoxicology Research Group, Institute for Risk Assessment Sciences (IRAS), Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Martin F Wilks
- Swiss Centre for Human Applied Toxicology, SCAHT, University of Basle, Switzerland
| | - Hilda Witters
- VITO, Flemish Institute for Technological Research, Unit Environmental Risk and Health, Mol, Belgium
| | - Marie-Gabrielle Zurich
- Swiss Centre for Human Applied Toxicology, SCAHT, University of Basle, Switzerland.,Department of Physiology, University of Lausanne, Lausanne, Switzerland
| | - Marcel Leist
- Center for Alternatives to Animal Testing, CAAT-Europe, University of Konstanz, Konstanz, Germany.,In vitro Toxicology and Biomedicine, Department of Biology, University of Konstanz, Konstanz, Germany
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21
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Scialli AR, Daston G, Chen C, Coder PS, Euling SY, Foreman J, Hoberman AM, Hui J, Knudsen T, Makris SL, Morford L, Piersma AH, Stanislaus D, Thompson KE. Rethinking developmental toxicity testing: Evolution or revolution? Birth Defects Res 2018; 110:840-850. [PMID: 29436169 DOI: 10.1002/bdr2.1212] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 12/18/2017] [Accepted: 01/29/2018] [Indexed: 12/31/2022]
Abstract
BACKGROUND Current developmental toxicity testing adheres largely to protocols suggested in 1966 involving the administration of test compound to pregnant laboratory animals. After more than 50 years of embryo-fetal development testing, are we ready to consider a different approach to human developmental toxicity testing? METHODS A workshop was held under the auspices of the Developmental and Reproductive Toxicology Technical Committee of the ILSI Health and Environmental Sciences Institute to consider how we might design developmental toxicity testing if we started over with 21st century knowledge and techniques (revolution). We first consider what changes to the current protocols might be recommended to make them more predictive for human risk (evolution). RESULTS The evolutionary approach includes modifications of existing protocols and can include humanized models, disease models, more accurate assessment and testing of metabolites, and informed approaches to dose selection. The revolution could start with hypothesis-driven testing where we take what we know about a compound or close analog and answer specific questions using targeted experimental techniques rather than a one-protocol-fits-all approach. Central to the idea of hypothesis-driven testing is the concept that testing can be done at the level of mode of action. It might be feasible to identify a small number of key events at a molecular or cellular level that predict an adverse outcome and for which testing could be performed in vitro or in silico or, rarely, using limited in vivo models. Techniques for evaluating these key events exist today or are in development. DISCUSSION Opportunities exist for refining and then replacing current developmental toxicity testing protocols using techniques that have already been developed or are within reach.
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Affiliation(s)
- Anthony R Scialli
- Reproductive Toxicology Center and Scialli Consulting LLC, Washington, DC
| | | | - Connie Chen
- ILSI Health and Environmental Sciences Institute, Washington, DC
| | | | - Susan Y Euling
- Office of Children's Health Protection, U.S. Environmental Protection Agency, Washington, DC
| | | | | | - Julia Hui
- Celgene Corporation, Summit, New Jersey
| | - Thomas Knudsen
- National Center for Computational Toxicology, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina
| | - Susan L Makris
- National Center for Environmental Assessment, U.S. Environmental Protection Agency, Washington, DC
| | | | - Aldert H Piersma
- Center for Health Protection, National Institute for Public Health and the Environment RIVM, Bilthoven and Institute for Risk Assessment Sciences, Utrecht University, Utrecht, Netherlands
| | | | - Kary E Thompson
- Drug Safety Evaluation, Bristol-Myers Squibb, New Brunswick, New Jersey
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22
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Velazquez JJ, Su E, Cahan P, Ebrahimkhani MR. Programming Morphogenesis through Systems and Synthetic Biology. Trends Biotechnol 2017; 36:415-429. [PMID: 29229492 DOI: 10.1016/j.tibtech.2017.11.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 11/15/2017] [Accepted: 11/16/2017] [Indexed: 01/07/2023]
Abstract
Mammalian tissue development is an intricate, spatiotemporal process of self-organization that emerges from gene regulatory networks of differentiating stem cells. A major goal in stem cell biology is to gain a sufficient understanding of gene regulatory networks and cell-cell interactions to enable the reliable and robust engineering of morphogenesis. Here, we review advances in synthetic biology, single cell genomics, and multiscale modeling, which, when synthesized, provide a framework to achieve the ambitious goal of programming morphogenesis in complex tissues and organoids.
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Affiliation(s)
- Jeremy J Velazquez
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA; Authors contributed equally
| | - Emily Su
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Authors contributed equally
| | - Patrick Cahan
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Mo R Ebrahimkhani
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA; Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine and Science, Phoenix, AZ, USA.
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23
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Staal YC, Pennings JL, Hessel EV, Piersma AH. Advanced Toxicological Risk Assessment by Implementation of Ontologies Operationalized in Computational Models. ACTA ACUST UNITED AC 2017. [DOI: 10.1089/aivt.2017.0019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Yvonne C.M. Staal
- Center for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
| | - Jeroen L.A. Pennings
- Center for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
| | - Ellen V.S. Hessel
- Center for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
| | - Aldert H. Piersma
- Center for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
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24
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Piersma AH, van Benthem J, Ezendam J, Kienhuis AS. Validation redefined. Toxicol In Vitro 2017; 46:163-165. [PMID: 29024777 DOI: 10.1016/j.tiv.2017.10.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 10/03/2017] [Accepted: 10/08/2017] [Indexed: 12/28/2022]
Affiliation(s)
- Aldert H Piersma
- Center for Health Protection, National Institute for Public Health and the Environment RIVM, The Netherlands; Institute for Risk Assessment Sciences IRAS, Utrecht University, The Netherlands.
| | - Jan van Benthem
- Center for Health Protection, National Institute for Public Health and the Environment RIVM, The Netherlands
| | - Janine Ezendam
- Center for Health Protection, National Institute for Public Health and the Environment RIVM, The Netherlands
| | - Anne S Kienhuis
- Center for Health Protection, National Institute for Public Health and the Environment RIVM, The Netherlands
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25
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Knudsen TB, Klieforth B, Slikker W. Programming microphysiological systems for children's health protection. Exp Biol Med (Maywood) 2017; 242:1586-1592. [PMID: 28658972 DOI: 10.1177/1535370217717697] [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: 12/31/2022] Open
Abstract
Microphysiological systems (MPS) and computer simulation models that recapitulate the underlying biology and toxicology of critical developmental transitions are emerging tools for developmental effects assessment of drugs/chemicals. Opportunities and challenges exist for their application to alternative, more public health relevant and efficient chemical toxicity testing methods. This is especially pertinent to children's health research and the evaluation of complex embryological and reproductive impacts of drug/chemical exposure. Scaling these technologies to higher throughput is a key challenge and drives the need for in silico models for quantitative prediction of developmental toxicity to inform safety assessments. One example is cellular agent-based models, constructed from extant embryology, that produce data useful to simulate critical developmental transitions and thereby predict phenotypic consequences of disruption in silico. Biologically inspired MPS models built from human induced pluripotent stem (iPS)-derived cells and synthetic matrices that recapitulate organ-specific physiologies and native tissue architectures are providing exciting new research opportunities to advance the assessment of developmental toxicity and offer the possibility of deriving a full 'human on a chip' system, or a 'Homunculus.' Impact statement This 'commentary' summarizes research needs and opportunities for engineered MPS models for developmental and reproductive toxicity testing. Emerging concepts can be taken forward to a virtual tissue modeling framework for assessing chemical (and non-chemical) stressors on human development. These models will advance children's health research, both basic and translational and new ways to evaluate complex embryological and reproductive impacts of drug and chemical exposures to inform safety assessments.
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Affiliation(s)
- T B Knudsen
- 1 National Center for Computational Toxicology/EPA, Research Triangle Park, NC 27711, USA
| | - B Klieforth
- 2 National Center for Environmental Research/EPA, Washington, DC 20460, USA
| | - W Slikker
- 3 National Center for Toxicological Research/FDA, Jefferson, AR 72079, USA
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26
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Piersma AH, Hessel EV, Staal YC. Retinoic acid in developmental toxicology: Teratogen, morphogen and biomarker. Reprod Toxicol 2017; 72:53-61. [PMID: 28591664 DOI: 10.1016/j.reprotox.2017.05.014] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 05/08/2017] [Accepted: 05/30/2017] [Indexed: 12/11/2022]
Abstract
This review explores the usefulness retinoic acid (RA) related physiological factors as possible biomarkers of embryotoxicity. RA is involved in the morphogenesis of the early embryo as well as in the development and maturation of a wide variety of organ anlagen. The region-specific homeostasis of RA in the embryo is in many ways the driving force determining developmental cell proliferation versus differentiation. As a consequence, RA concentrations are carefully controlled in time and space in the developing embryo. RA deficiency and overdosing both result in characteristic patterns of malformations that may involve many different organ systems. The central role of RA in embryo development provides us with a set of sensitive biomarkers that may be employed in developmental toxicity testing. This includes the synthesizing and metabolizing enzymes of RA, but also a myriad of related morphogenetic factors and their genes, of which the expression may be affected by changes in RA balance. Several examples of embryotoxicants interfering with the homeostasis of RA and related parameters have been described. A preliminary adverse outcome pathway framework for RA mediated malformations has been published. Expansion of this framework and its application in developmental toxicity testing may allow the detection of a large variety of embryotoxicants with diverse modes of action. RA homeostasis therefore provides a promising set of molecular tools that may be employed in the advancement of mode of action driven animal-free developmental toxicity testing.
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Affiliation(s)
- Aldert H Piersma
- Center for Health Protection, National Institute for Public Health and the Environment RIVM, Antonie van Leeuwenhoeklaan 9, P.O. Box 1, 3720 BA Bilthoven, The Netherlands.
| | - Ellen V Hessel
- Center for Health Protection, National Institute for Public Health and the Environment RIVM, Antonie van Leeuwenhoeklaan 9, P.O. Box 1, 3720 BA Bilthoven, The Netherlands
| | - Yvonne C Staal
- Center for Health Protection, National Institute for Public Health and the Environment RIVM, Antonie van Leeuwenhoeklaan 9, P.O. Box 1, 3720 BA Bilthoven, The Netherlands
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27
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Leung MCK, Procter AC, Goldstone JV, Foox J, DeSalle R, Mattingly CJ, Siddall ME, Timme-Laragy AR. Applying evolutionary genetics to developmental toxicology and risk assessment. Reprod Toxicol 2017; 69:174-186. [PMID: 28267574 PMCID: PMC5829367 DOI: 10.1016/j.reprotox.2017.03.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 02/27/2017] [Accepted: 03/02/2017] [Indexed: 12/26/2022]
Abstract
Evolutionary thinking continues to challenge our views on health and disease. Yet, there is a communication gap between evolutionary biologists and toxicologists in recognizing the connections among developmental pathways, high-throughput screening, and birth defects in humans. To increase our capability in identifying potential developmental toxicants in humans, we propose to apply evolutionary genetics to improve the experimental design and data interpretation with various in vitro and whole-organism models. We review five molecular systems of stress response and update 18 consensual cell-cell signaling pathways that are the hallmark for early development, organogenesis, and differentiation; and revisit the principles of teratology in light of recent advances in high-throughput screening, big data techniques, and systems toxicology. Multiscale systems modeling plays an integral role in the evolutionary approach to cross-species extrapolation. Phylogenetic analysis and comparative bioinformatics are both valuable tools in identifying and validating the molecular initiating events that account for adverse developmental outcomes in humans. The discordance of susceptibility between test species and humans (ontogeny) reflects their differences in evolutionary history (phylogeny). This synthesis not only can lead to novel applications in developmental toxicity and risk assessment, but also can pave the way for applying an evo-devo perspective to the study of developmental origins of health and disease.
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Affiliation(s)
- Maxwell C K Leung
- Nicholas School of the Environment, Duke University, Durham, NC, United States.
| | - Andrew C Procter
- Institute for Advanced Analytics, North Carolina State University, Raleigh, NC, United States
| | - Jared V Goldstone
- Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
| | - Jonathan Foox
- Department of Invertebrate Zoology, American Museum of Natural History, New York, New York, United States
| | - Robert DeSalle
- Department of Invertebrate Zoology, American Museum of Natural History, New York, New York, United States
| | - Carolyn J Mattingly
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, United States
| | - Mark E Siddall
- Department of Invertebrate Zoology, American Museum of Natural History, New York, New York, United States
| | - Alicia R Timme-Laragy
- Department of Environmental Health Sciences, University of Massachusetts, Amherst, MA, United States
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28
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Hutson MS, Leung MCK, Baker NC, Spencer RM, Knudsen TB. Computational Model of Secondary Palate Fusion and Disruption. Chem Res Toxicol 2017; 30:965-979. [PMID: 28045533 DOI: 10.1021/acs.chemrestox.6b00350] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Morphogenetic events are driven by cell-generated physical forces and complex cellular dynamics. To improve our capacity to predict developmental effects from chemical-induced cellular alterations, we built a multicellular agent-based model in CompuCell3D that recapitulates the cellular networks and collective cell behavior underlying growth and fusion of the mammalian secondary palate. The model incorporated multiple signaling pathways (TGFβ, BMP, FGF, EGF, and SHH) in a biological framework to recapitulate morphogenetic events from palatal outgrowth through midline fusion. It effectively simulated higher-level phenotypes (e.g., midline contact, medial edge seam (MES) breakdown, mesenchymal confluence, and fusion defects) in response to genetic or environmental perturbations. Perturbation analysis of various control features revealed model functionality with respect to cell signaling systems and feedback loops for growth and fusion, diverse individual cell behaviors and collective cellular behavior leading to physical contact and midline fusion, and quantitative analysis of the TGF/EGF switch that controls MES breakdown-a key event in morphogenetic fusion. The virtual palate model was then executed with theoretical chemical perturbation scenarios to simulate switch behavior leading to a disruption of fusion following chronic (e.g., dioxin) and acute (e.g., retinoic acid) chemical exposures. This computer model adds to similar systems models toward an integrative "virtual embryo" for simulation and quantitative prediction of adverse developmental outcomes following genetic perturbation and/or environmental disruption.
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Affiliation(s)
- M Shane Hutson
- Department of Physics & Astronomy, Department of Biological Sciences and Vanderbilt Institute for Integrative Biosystem Research & Education, Vanderbilt University , Nashville, Tennessee 37235, United States.,Oak Ridge Institute for Science & Education , Oak Ridge, Tennessee 37832, United States
| | - Maxwell C K Leung
- Oak Ridge Institute for Science & Education , Oak Ridge, Tennessee 37832, United States
| | - Nancy C Baker
- Leidos , Research Triangle Park, Durham, North Carolina 27711 United States
| | - Richard M Spencer
- Leidos , Research Triangle Park, Durham, North Carolina 27711 United States
| | - Thomas B Knudsen
- National Center for Computational Toxicology, Office of Research & Development, U.S. Environmental Protection Agency , Research Triangle Park, Durham, North Carolina 27711, United States
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