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Villeneuve DL, Bush K, Hazemi M, Hoang JX, Le M, Blackwell BR, Stacy E, Flynn KM. Derivation of Transcriptomics-Based Points of Departure for 20 Per- or Polyfluoroalkyl Substances Using a Larval Fathead Minnow (Pimephales promelas) Reduced Transcriptome Assay. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2024. [PMID: 38415853 DOI: 10.1002/etc.5825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 12/18/2023] [Accepted: 01/08/2024] [Indexed: 02/29/2024]
Abstract
Traditional toxicity testing has been unable to keep pace with the introduction of new chemicals into commerce. Consequently, there are limited or no toxicity data for many chemicals to which fish and wildlife may be exposed. Per- and polyfluoroalkyl substances (PFAS) are emblematic of this issue in that ecological hazards of most PFAS remain uncharacterized. The present study employed a high-throughput assay to identify the concentration at which 20 PFAS, with diverse properties, elicited a concerted gene expression response (termed a transcriptomics-based point of departure [tPOD]) in larval fathead minnows (Pimephales promelas; 5-6 days postfertilization) exposed for 24 h. Based on a reduced transcriptome approach that measured whole-body expression of 1832 genes, the median tPOD for the 20 PFAS tested was 10 µM. Longer-chain carboxylic acids (12-13 C-F); an eight-C-F dialcohol, N-alkyl sulfonamide; and telomer sulfonic acid were among the most potent PFAS, eliciting gene expression responses at concentrations <1 µM. With a few exceptions, larval fathead minnow tPODs were concordant with those based on whole-transcriptome response in human cell lines. However, larval fathead minnow tPODs were often greater than those for Daphnia magna exposed to the same PFAS. The tPODs overlapped concentrations at which other sublethal effects have been reported in fish (available for 10 PFAS). Nonetheless, fathead minnow tPODs were orders of magnitude higher than aqueous PFAS concentrations detected in tributaries of the North American Great Lakes, suggesting a substantial margin of safety. Overall, results broadly support the use of a fathead minnow larval transcriptomics assay to derive screening-level potency estimates for use in ecological risk-based prioritization. Environ Toxicol Chem 2024;00:1-16. © 2024 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.
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Affiliation(s)
- Daniel L Villeneuve
- Great Lakes Toxicology and Ecology Division, US Environmental Protection Agency, Duluth, Minnesota
| | - Kendra Bush
- Research Participant at Great Lakes Toxicology and Ecology Division, Oak Ridge Institute for Science and Education, Duluth, Minnesota, USA
| | - Monique Hazemi
- Research Participant at Great Lakes Toxicology and Ecology Division, Oak Ridge Institute for Science and Education, Duluth, Minnesota, USA
| | - John X Hoang
- Research Participant at Great Lakes Toxicology and Ecology Division, Oak Ridge Institute for Science and Education, Duluth, Minnesota, USA
| | - Michelle Le
- Research Participant at Great Lakes Toxicology and Ecology Division, Oak Ridge Institute for Science and Education, Duluth, Minnesota, USA
| | - Brett R Blackwell
- Great Lakes Toxicology and Ecology Division, US Environmental Protection Agency, Duluth, Minnesota
- Bioscience Division, Biochemistry and Biotechnology Group, Los Alamos National Laboratory, Los Alamos, Minnesota, USA
| | - Emma Stacy
- Great Lakes Toxicology and Ecology Division, US Environmental Protection Agency, Duluth, Minnesota
| | - Kevin M Flynn
- Great Lakes Toxicology and Ecology Division, US Environmental Protection Agency, Duluth, Minnesota
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Chen XY, Li YY, Lv L, Xiong YM, Qin ZF. The brominated flame retardant tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) as well as hexabromocyclododecane lead to lipid disorders in mice. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 341:122895. [PMID: 37949162 DOI: 10.1016/j.envpol.2023.122895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 10/10/2023] [Accepted: 11/05/2023] [Indexed: 11/12/2023]
Abstract
The brominated flame retardant tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) (TBBPA-DBMPE) is a recommended substitute for hexabromocyclododecane (HBCD), a banned persistent organic pollutant, yet its potential toxicities remains largely unexplored. Here, we investigated the effects of a long-term exposure to TBBPA-DBMPE at nominal doses of 50 and 1000 μg/kg/d on lipid homeostasis in CD-1 mice, in comparison with 50 μg/kg/d HBCD as a positive control. Male pups received chemical treatments through maternal administration via drinking water from postnatal day 0-21, followed by direct administration through drinking water after weaning. On the 23rd week after treatment, the oral lipid tolerance test revealed that low-dose TBBPA-DBMPE as well as HBCD affected lipid tolerance, although the fasting serum triglyceride (TG) levels were not altered. When chemical treatment was extended to the 32nd week, TBBPA-DBMPE-treated animals displayed adipocyte hypertrophy in both white adipose tissue (eWAT) and brown adipose tissue (BAT) and hepatic steatosis, which was largely consistent with the effects of HBCD. These findings indicate that like HBCD, TBBPA-DBMPE led to increased lipid load in mice. Interestingly, we also observed intestinal histological changes, coupled with increased expression of lipid absorption-related genes in both HBCD and TBBPA-DBMPE treatments, suggesting increased lipid absorption. This was supported by in vitro findings that both HBCD and TBBPA-DBMPE promoted lipid accumulation in IEC-6 cells under the stress of oleic acid for 6 h, implying that altered lipid absorption by the intestine may partly contributed to increased lipid load in mice. Overall, the effects of 50 μg/kg/d TBBPA-DBMPE in terms of some parameters were comparable with 50 μg/kg/d HBCD, suggesting that TBBPA-DBMPE may not be an ideal substitute of HBCD.
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Affiliation(s)
- Xuan-Yue Chen
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yuan-Yuan Li
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lin Lv
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yi-Ming Xiong
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhan-Fen Qin
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
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Ding Y, Chen Y, Feng W, Huang G, Dong M, Zhao T, Chen N, Yang L, Mao G, Wu X. Persistent immune injury induced by short-term decabromodiphenyl ether (BDE-209) exposure to female middle-aged Balb/c mice. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:111325-111343. [PMID: 37814044 DOI: 10.1007/s11356-023-30148-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 09/25/2023] [Indexed: 10/11/2023]
Abstract
Decabromodiphenyl ether (BDE-209), widely used in various industries for its excellent flame-retardant performance, could be enriched in humans and is closely associated with immune impairment. In addition, immune system is gradually declined and becoming more sensitive to environmental pollutants in the ageing process. Therefore, the immunotoxicity of BDE-209 (4, 40, and 400 mg/kg/day) to middle-aged mice and its recovery and susceptibility was first to be comprehensively investigated in this study. The results showed that BDE-209 exposure could lead to oxidative injury to immune organs (spleen, thymus, and liver), impair humoral (immunoglobulins), cellular (lymphopoiesis), and non-specific immunity, and disturb the expressions of the genes related to Th1/Th2 balance (T helper cells) in the middle-aged mice. In addition, Integrated Biomarker Response (IBR) indicated that BDE-209-induced immune impairment was challenging to self-regulated, and even exacerbated after 21 days of recovery and oxidative injury in immune organs could be the main reason. Furthermore, factorial analysis showed that middle-aged mice exposed to BDE-209 suffered from greater immune impairment than adult mice, and the immune impairment in aged mice is more difficult to be self-repaired than that in adult mice. It can be seen that the aged tend to suffer from BDE-209-induced persistent immune impairment and health threats.
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Affiliation(s)
- Yangyang Ding
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
- The Laboratory Animal Research Center of Jiangsu University, Zhenjiang, Jiangsu, China
| | - Yao Chen
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
- Institute of Environmental Health and Ecological Security, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Weiwei Feng
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
- Institute of Environmental Health and Ecological Security, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Guijuan Huang
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Mingyue Dong
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Ting Zhao
- School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Na Chen
- Zhenjiang Food and Drug Supervision and Inspection Center, Zhenjiang, Jiangsu, China
| | - Liuqing Yang
- School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Guanghua Mao
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, China.
| | - Xiangyang Wu
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
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Itkonen A, Hakkola J, Rysä J. Adverse outcome pathway for pregnane X receptor-induced hypercholesterolemia. Arch Toxicol 2023; 97:2861-2877. [PMID: 37642746 PMCID: PMC10504106 DOI: 10.1007/s00204-023-03575-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 08/02/2023] [Indexed: 08/31/2023]
Abstract
Pharmaceuticals and environmental contaminants contribute to hypercholesterolemia. Several chemicals known to cause hypercholesterolemia, activate pregnane X receptor (PXR). PXR is a nuclear receptor, classically identified as a sensor of chemical environment and regulator of detoxification processes. Later, PXR activation has been shown to disrupt metabolic functions such as lipid metabolism and recent findings have shown PXR activation to promote hypercholesterolemia through multiple mechanisms. Hypercholesterolemia is a major causative risk factor for atherosclerosis and greatly promotes global health burden. Metabolic disruption by PXR activating chemicals leading to hypercholesterolemia represents a novel toxicity pathway of concern and requires further attention. Therefore, we constructed an adverse outcome pathway (AOP) by collecting the available knowledge considering the molecular mechanisms for PXR-mediated hypercholesterolemia. AOPs are tools of modern toxicology for systematizing mechanistic knowledge to assist health risk assessment of chemicals. AOPs are formalized and structured linear concepts describing a link between molecular initiating event (MIE) and adverse outcome (AO). MIE and AO are connected via key events (KE) through key event relationships (KER). We present a plausible route of how PXR activation (MIE) leads to hypercholesterolemia (AO) through direct regulation of cholesterol synthesis and via activation of sterol regulatory element binding protein 2-pathway.
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Affiliation(s)
- Anna Itkonen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland
| | - Jukka Hakkola
- Research Unit of Biomedicine and Internal Medicine, Biocenter Oulu, Medical Research Center Oulu, University of Oulu and Oulu University Hospital, Oulu, Finland
| | - Jaana Rysä
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland.
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5
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Reardon AJF, Farmahin R, Williams A, Meier MJ, Addicks GC, Yauk CL, Matteo G, Atlas E, Harrill J, Everett LJ, Shah I, Judson R, Ramaiahgari S, Ferguson SS, Barton-Maclaren TS. From vision toward best practices: Evaluating in vitro transcriptomic points of departure for application in risk assessment using a uniform workflow. FRONTIERS IN TOXICOLOGY 2023; 5:1194895. [PMID: 37288009 PMCID: PMC10242042 DOI: 10.3389/ftox.2023.1194895] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 05/03/2023] [Indexed: 06/09/2023] Open
Abstract
The growing number of chemicals in the current consumer and industrial markets presents a major challenge for regulatory programs faced with the need to assess the potential risks they pose to human and ecological health. The increasing demand for hazard and risk assessment of chemicals currently exceeds the capacity to produce the toxicity data necessary for regulatory decision making, and the applied data is commonly generated using traditional approaches with animal models that have limited context in terms of human relevance. This scenario provides the opportunity to implement novel, more efficient strategies for risk assessment purposes. This study aims to increase confidence in the implementation of new approach methods in a risk assessment context by using a parallel analysis to identify data gaps in current experimental designs, reveal the limitations of common approaches deriving transcriptomic points of departure, and demonstrate the strengths in using high-throughput transcriptomics (HTTr) to derive practical endpoints. A uniform workflow was applied across six curated gene expression datasets from concentration-response studies containing 117 diverse chemicals, three cell types, and a range of exposure durations, to determine tPODs based on gene expression profiles. After benchmark concentration modeling, a range of approaches was used to determine consistent and reliable tPODs. High-throughput toxicokinetics were employed to translate in vitro tPODs (µM) to human-relevant administered equivalent doses (AEDs, mg/kg-bw/day). The tPODs from most chemicals had AEDs that were lower (i.e., more conservative) than apical PODs in the US EPA CompTox chemical dashboard, suggesting in vitro tPODs would be protective of potential effects on human health. An assessment of multiple data points for single chemicals revealed that longer exposure duration and varied cell culture systems (e.g., 3D vs. 2D) lead to a decreased tPOD value that indicated increased chemical potency. Seven chemicals were flagged as outliers when comparing the ratio of tPOD to traditional POD, thus indicating they require further assessment to better understand their hazard potential. Our findings build confidence in the use of tPODs but also reveal data gaps that must be addressed prior to their adoption to support risk assessment applications.
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Affiliation(s)
- Anthony J. F. Reardon
- Existing Substances Risk Assessment Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, Canada
| | - Reza Farmahin
- Existing Substances Risk Assessment Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, Canada
| | - Andrew Williams
- Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, Canada
| | - Matthew J. Meier
- Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, Canada
| | - Gregory C. Addicks
- Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, Canada
| | - Carole L. Yauk
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Geronimo Matteo
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Ella Atlas
- Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, Canada
- Department of Biochemistry, University of Ottawa, Ottawa, ON, Canada
| | - Joshua Harrill
- Center for Computational Toxicology and Exposure, US Environmental Protection Agency, Durham, NC, United States
| | - Logan J. Everett
- Center for Computational Toxicology and Exposure, US Environmental Protection Agency, Durham, NC, United States
| | - Imran Shah
- Center for Computational Toxicology and Exposure, US Environmental Protection Agency, Durham, NC, United States
| | - Richard Judson
- Center for Computational Toxicology and Exposure, US Environmental Protection Agency, Durham, NC, United States
| | - Sreenivasa Ramaiahgari
- Division of Translational Toxicology, Mechanistic Toxicology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Durham, NC, United States
| | - Stephen S. Ferguson
- Division of Translational Toxicology, Mechanistic Toxicology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Durham, NC, United States
| | - Tara S. Barton-Maclaren
- Existing Substances Risk Assessment Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, Canada
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6
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Marques ML, Cairrao E. Occurrence and Health Effects of Hexabromocyclododecane: An Updated Review. TOXICS 2023; 11:toxics11050409. [PMID: 37235223 DOI: 10.3390/toxics11050409] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 04/17/2023] [Accepted: 04/24/2023] [Indexed: 05/28/2023]
Abstract
Hexabromocyclododecane (HBCD) is a non-aromatic compound belonging to the bromine flame retardant family and is a known persistent organic pollutant (POP). This compound accumulates easily in the environment and has a high half-life in water. With a variety of uses, the HBCD is found in house dust, electronics, insulation, and construction. There are several isomers and the most studied are α-, β-, and γ-HBCD. Initially used as a substitute for other flame retardants, the polybrominated diphenyl ethers (PBDEs), the discovery of its role as a POP made HBCD use and manufacturing restricted in Europe and other countries. The adverse effects on the environment and human health have been piling, either as a result from its accumulation or considering its power as an endocrine disruptor (ED). Furthermore, it has also been proven that it has detrimental effects on the neuronal system, endocrine system, cardiovascular system, liver, and the reproductive system. HBCD has also been linked to cytokine production, DNA damage, increased cell apoptosis, increased oxidative stress, and reactive oxygen species (ROS) production. Therefore, this review aims to compile the most recent studies regarding the negative effects of this compound on the environment and human health, describing the possible mechanisms by which this compound acts and its possible toxic effects.
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Affiliation(s)
- Maria Lopes Marques
- CICS-UBI, Health Sciences Research Centre, University of Beira Interior, 6200-506 Covilhã, Portugal
| | - Elisa Cairrao
- CICS-UBI, Health Sciences Research Centre, University of Beira Interior, 6200-506 Covilhã, Portugal
- FCS-UBI, Faculty of Health Sciences, University of Beira Interior, 6200-506 Covilhã, Portugal
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Chauhan V, Yu J, Vuong N, Haber LT, Williams A, Auerbach SS, Beaton D, Wang Y, Stainforth R, Wilkins RC, Azzam EI, Richardson RB, Khan MGM, Jadhav A, Burtt JJ, Leblanc J, Randhawa K, Tollefsen KE, Yauk CL. Considerations for application of benchmark dose modeling in radiation research: workshop highlights. Int J Radiat Biol 2023; 99:1320-1331. [PMID: 36881459 DOI: 10.1080/09553002.2023.2181998] [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: 08/28/2022] [Revised: 01/18/2023] [Accepted: 02/06/2023] [Indexed: 02/24/2023]
Abstract
BACKGROUND Exposure to different forms of ionizing radiation occurs in diverse occupational, medical, and environmental settings. Improving the accuracy of the estimated health risks associated with exposure is therefore, essential for protecting the public, particularly as it relates to chronic low dose exposures. A key aspect to understanding health risks is precise and accurate modeling of the dose-response relationship. Toward this vision, benchmark dose (BMD) modeling may be a suitable approach for consideration in the radiation field. BMD modeling is already extensively used for chemical hazard assessments and is considered statistically preferable to identifying low and no observed adverse effects levels. BMD modeling involves fitting mathematical models to dose-response data for a relevant biological endpoint and identifying a point of departure (the BMD, or its lower bound). Recent examples in chemical toxicology show that when applied to molecular endpoints (e.g. genotoxic and transcriptional endpoints), BMDs correlate to points of departure for more apical endpoints such as phenotypic changes (e.g. adverse effects) of interest to regulatory decisions. This use of BMD modeling may be valuable to explore in the radiation field, specifically in combination with adverse outcome pathways, and may facilitate better interpretation of relevant in vivo and in vitro dose-response data. To advance this application, a workshop was organized on June 3rd, 2022, in Ottawa, Ontario that brought together BMD experts in chemical toxicology and the radiation scientific community of researchers, regulators, and policy-makers. The workshop's objective was to introduce radiation scientists to BMD modeling and its practical application using case examples from the chemical toxicity field and demonstrate the BMDExpress software using a radiation dataset. Discussions focused on the BMD approach, the importance of experimental design, regulatory applications, its use in supporting the development of adverse outcome pathways, and specific radiation-relevant examples. CONCLUSIONS Although further deliberations are needed to advance the use of BMD modeling in the radiation field, these initial discussions and partnerships highlight some key steps to guide future undertakings related to new experimental work.
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Affiliation(s)
- Vinita Chauhan
- Consumer and Clinical Radiation Protection Bureau, Health Canada, Ottawa, Canada
| | - Jihang Yu
- Radiobiology and Health Branch, Canadian Nuclear Laboratories, Chalk River, Canada
| | - Ngoc Vuong
- Radiation Protection Bureau, Health Canada, Ottawa, Canada
| | - Lynne T Haber
- Department of Environmental and Public Health Sciences, Risk Science Center, University of Cincinnati, Cincinnati, OH, USA
| | - Andrew Williams
- Environmental Health Science and Research Bureau, Health Science and Research Bureau, Health Canada, Ottawa, Canada
| | - Scott S Auerbach
- National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - Danielle Beaton
- Radiobiology and Health Branch, Canadian Nuclear Laboratories, Chalk River, Canada
| | - Yi Wang
- Radiobiology and Health Branch, Canadian Nuclear Laboratories, Chalk River, Canada
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
| | | | - Ruth C Wilkins
- Consumer and Clinical Radiation Protection Bureau, Health Canada, Ottawa, Canada
| | - Edouard I Azzam
- Radiobiology and Health Branch, Canadian Nuclear Laboratories, Chalk River, Canada
- Department of Radiology, New Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Richard B Richardson
- Radiobiology and Health Branch, Canadian Nuclear Laboratories, Chalk River, Canada
- Medical Physics Unit, McGill University, Montreal, QC, Canada
| | | | - Ashok Jadhav
- Radiobiology and Health Branch, Canadian Nuclear Laboratories, Chalk River, Canada
| | - Julie J Burtt
- Directorate of Environmental and Radiation Protection and Assessment, Canadian Nuclear Safety Commission, Ottawa, Canada
| | - Julie Leblanc
- Directorate of Environmental and Radiation Protection and Assessment, Canadian Nuclear Safety Commission, Ottawa, Canada
| | - Kristi Randhawa
- Directorate of Environmental and Radiation Protection and Assessment, Canadian Nuclear Safety Commission, Ottawa, Canada
| | - Knut Erik Tollefsen
- Norwegian Institute for Water Research (NIVA), Oslo, Norway
- Norwegian University of Life Sciences (NMBU), Ås, Norway
- Centre for Environmental Radioactivity, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Carole L Yauk
- Department of Biology, University of Ottawa, Ottawa, Canada
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Proença S, van Sabben N, Legler J, Kamstra JH, Kramer NI. The effects of hexabromocyclododecane on the transcriptome and hepatic enzyme activity in three human HepaRG-based models. Toxicology 2023; 485:153411. [PMID: 36572169 DOI: 10.1016/j.tox.2022.153411] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 12/09/2022] [Accepted: 12/21/2022] [Indexed: 12/24/2022]
Abstract
The disruption of thyroid hormone homeostasis by hexabromocyclododecane (HBCD) in rodents is hypothesized to be due to HBCD increasing the hepatic clearance of thyroxine (T4). The extent to which these effects are relevant to humans is unclear. To evaluate HBCD effects on humans, the activation of key hepatic nuclear receptors and the consequent disruption of thyroid hormone homeostasis were studied in different human hepatic cell models. The hepatoma cell line, HepaRG, cultured as two-dimensional (2D), sandwich (SW) and spheroid (3D) cultures, and primary human hepatocytes (PHH) cultured as sandwich were exposed to 1 and 10 µM HBCD and characterized for their transcriptome changes. Pathway enrichment analysis showed that 3D models, followed by SW, had a stronger transcriptome response to HBCD, which is explained by the higher expression of hepatic nuclear receptors but also greater accumulation of HBCD measured inside cells in these models. The Pregnane X receptor pathway is one of the pathways most upregulated across the three hepatic models, followed by the constitutive androstane receptor and general hepatic nuclear receptors pathways. Lipid metabolism pathways had a downregulation tendency in all exposures and in both PHH and the three cultivation modes of HepaRG. The activity of enzymes related to PXR/CAR induction and T4 metabolism were evaluated in the three different types of HepaRG cultures exposed to HBCD for 48 h. Reference inducers, rifampicin and PCB-153 did affect 2D and SW HepaRG cultures' enzymatic activity but not 3D. HBCD did not induce the activity of any of the studied enzymes in any of the cell models and culture methods. This study illustrates that for nuclear receptor-mediated T4 disruption, transcriptome changes might not be indicative of an actual adverse effect. Clarification of the reasons for the lack of translation is essential to evaluate new chemicals' potential to be thyroid hormone disruptors by altering thyroid hormone metabolism.
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Affiliation(s)
- Susana Proença
- Department of Toxicology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands; Toxicology Division, Wageningen University, Wageningen, the Netherlands.
| | - Nick van Sabben
- Department of Toxicology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands
| | - Juliette Legler
- Department of Toxicology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands
| | - Jorke H Kamstra
- Department of Toxicology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands
| | - Nynke I Kramer
- Department of Toxicology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands; Toxicology Division, Wageningen University, Wageningen, the Netherlands
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9
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Assessing the neurotoxicity of airborne nano-scale particulate matter in human iPSC-derived neurons using a transcriptomics benchmark dose model. Toxicol Appl Pharmacol 2022; 449:116109. [DOI: 10.1016/j.taap.2022.116109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 05/26/2022] [Accepted: 06/02/2022] [Indexed: 11/23/2022]
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10
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Microbiota and Transcriptomic Effects of an Essential Oil Blend and Its Delivery Route Compared to an Antibiotic Growth Promoter in Broiler Chickens. Microorganisms 2022; 10:microorganisms10050861. [PMID: 35630307 PMCID: PMC9147064 DOI: 10.3390/microorganisms10050861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 04/12/2022] [Accepted: 04/14/2022] [Indexed: 11/25/2022] Open
Abstract
This study evaluated the effect of the delivery of a commercial essential oil blend containing the phytonutrients star anise, cinnamon, rosemary, and thyme oil (via different routes) on broiler chickens’ ileal and ceca microbiota and liver transcriptome compared to an antibiotic growth promoter. Eggs were incubated and allocated into three groups: non-injected, in ovo saline, and in ovo essential oil. On day 18 of incubation, 0.2 mL of essential oil in saline (dilution ratio of 2:1) or saline alone was injected into the amnion. At hatch, chicks were assigned to post-hatch treatment combinations: (A) a negative control (corn-wheat-soybean diet), (B) in-feed antibiotics, (C) in-water essential oil (250 mL/1000 L of drinking water), (D) in ovo saline, (E) in ovo essential oil, and (F) in ovo essential oil plus in-water essential oil in eight replicate cages (six birds/cage) and raised for 28 days. On days 21 and 28, one and two birds per cage were slaughtered, respectively, to collect gut content and liver tissues for further analysis. Alpha and beta diversity differed significantly between ileal and ceca samples but not between treatment groups. In-feed antibiotic treatment significantly increased the proportion of specific bacteria in the family Lachnospiraceae while reducing the proportion of bacteria in the genus Christensenellaceae in the ceca, compared to other treatments. Sex-controlled differential expression of genes related to cell signaling and tight junctions were recorded. This study provides data that could guide the use of these feed additives and a foundation for further research.
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11
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Basili D, Reynolds J, Houghton J, Malcomber S, Chambers B, Liddell M, Muller I, White A, Shah I, Everett LJ, Middleton A, Bender A. Latent Variables Capture Pathway-Level Points of Departure in High-Throughput Toxicogenomic Data. Chem Res Toxicol 2022; 35:670-683. [PMID: 35333521 PMCID: PMC9019810 DOI: 10.1021/acs.chemrestox.1c00444] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Estimation
of points of departure (PoDs) from high-throughput transcriptomic
data (HTTr) represents a key step in the development of next-generation
risk assessment (NGRA). Current approaches mainly rely on single key
gene targets, which are constrained by the information currently available
in the knowledge base and make interpretation challenging as scientists
need to interpret PoDs for thousands of genes or hundreds of pathways.
In this work, we aimed to address these issues by developing a computational
workflow to investigate the pathway concentration–response
relationships in a way that is not fully constrained by known biology
and also facilitates interpretation. We employed the Pathway-Level
Information ExtractoR (PLIER) to identify latent variables (LVs) describing
biological activity and then investigated in vitro LVs’ concentration–response
relationships using the ToxCast pipeline. We applied this methodology
to a published transcriptomic concentration–response data set
for 44 chemicals in MCF-7 cells and showed that our workflow can capture
known biological activity and discriminate between estrogenic and
antiestrogenic compounds as well as activity not aligning with the
existing knowledge base, which may be relevant in a risk assessment
scenario. Moreover, we were able to identify the known estrogen activity
in compounds that are not well-established ER agonists/antagonists
supporting the use of the workflow in read-across. Next, we transferred
its application to chemical compounds tested in HepG2, HepaRG, and
MCF-7 cells and showed that PoD estimates are in strong agreement
with those estimated using a recently developed Bayesian approach
(cor = 0.89) and in weak agreement with those estimated using a well-established
approach such as BMDExpress2 (cor = 0.57). These results demonstrate
the effectiveness of using PLIER in a concentration–response
scenario to investigate pathway activity in a way that is not fully
constrained by the knowledge base and to ease the biological interpretation
and support the development of an NGRA framework with the ability
to improve current risk assessment strategies for chemicals using
new approach methodologies.
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Affiliation(s)
- Danilo Basili
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, U.K.,Unilever, Safety and Environmental Assurance Centre (SEAC), Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, U.K
| | - Joe Reynolds
- Unilever, Safety and Environmental Assurance Centre (SEAC), Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, U.K
| | - Jade Houghton
- Unilever, Safety and Environmental Assurance Centre (SEAC), Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, U.K
| | - Sophie Malcomber
- Unilever, Safety and Environmental Assurance Centre (SEAC), Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, U.K
| | - Bryant Chambers
- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States
| | - Mark Liddell
- Unilever, Safety and Environmental Assurance Centre (SEAC), Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, U.K
| | - Iris Muller
- Unilever, Safety and Environmental Assurance Centre (SEAC), Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, U.K
| | - Andrew White
- Unilever, Safety and Environmental Assurance Centre (SEAC), Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, U.K
| | - Imran Shah
- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States
| | - Logan J Everett
- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States
| | - Alistair Middleton
- Unilever, Safety and Environmental Assurance Centre (SEAC), Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, U.K
| | - Andreas Bender
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, U.K
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12
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Chen Q, Chou WC, Lin Z. Integration of Toxicogenomics and Physiologically Based Pharmacokinetic Modeling in Human Health Risk Assessment of Perfluorooctane Sulfonate. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:3623-3633. [PMID: 35194992 DOI: 10.1021/acs.est.1c06479] [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] [Indexed: 06/14/2023]
Abstract
Toxicogenomics and physiologically based pharmacokinetic (PBPK) models are useful approaches in chemical risk assessment, but the methodology to incorporate toxicogenomic data into a PBPK model to inform risk assessment remains to be developed. This study aimed to develop a probabilistic human health risk assessment approach by integrating toxicogenomic dose-response data and PBPK modeling using perfluorooctane sulfonate (PFOS) as a case study. Based on the available human in vitro and mouse in vivo toxicogenomic data, we identified the differentially expressed genes (DEGs) at each exposure paradigm/duration. Kyoto Encyclopedia of Genes and Genomes and disease ontology enrichment analyses were conducted on the DEGs to identify significantly enriched pathways and diseases. The dose-response data of DEGs were analyzed using the Bayesian benchmark dose (BMD) method. Using a previously published PBPK model, the gene BMDs were converted to human equivalent doses (HEDs), which were summarized to pathway and disease HEDs and then extrapolated to reference doses (RfDs) by considering an uncertainty factor of 30 for mouse in vivo data and 10 for human in vitro data. The results suggested that the median RfDs at different exposure paradigms were similar to the 2016 U.S. Environmental Protection Agency's recommended RfD, while the RfDs for the most sensitive pathways and diseases were closer to the recent European Food Safety Authority's guidance values. In conclusion, genomic dose-response data and PBPK modeling can be integrated to become a useful alternative approach in risk assessment of environmental chemicals. This approach considers multiple endpoints, provides toxicity mechanistic insights, and does not rely on apical toxicity endpoints.
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Affiliation(s)
- Qiran Chen
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, Florida 32610, United States
- Center for Environmental and Human Toxicology, University of Florida, Gainesville, Florida 32608, United States
| | - Wei-Chun Chou
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, Florida 32610, United States
- Center for Environmental and Human Toxicology, University of Florida, Gainesville, Florida 32608, United States
| | - Zhoumeng Lin
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, Florida 32610, United States
- Center for Environmental and Human Toxicology, University of Florida, Gainesville, Florida 32608, United States
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13
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R-ODAF: Omics data analysis framework for regulatory application. Regul Toxicol Pharmacol 2022; 131:105143. [PMID: 35247516 DOI: 10.1016/j.yrtph.2022.105143] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 12/20/2021] [Accepted: 02/14/2022] [Indexed: 12/12/2022]
Abstract
Despite the widespread use of transcriptomics technologies in toxicology research, acceptance of the data by regulatory agencies to support the hazard assessment is still limited. Fundamental issues contributing to this are the lack of reproducibility in transcriptomics data analysis arising from variance in the methods used to generate data and differences in the data processing. While research applications are flexible in the way the data are generated and interpreted, this is not the case for regulatory applications where an unambiguous answer, possibly later subject to legal scrutiny, is required. A reference analysis framework would give greater credibility to the data and allow the practitioners to justify their use of an alternative bioinformatic process by referring to a standard. In this publication, we propose a method called omics data analysis framework for regulatory application (R-ODAF), which has been built as a user-friendly pipeline to analyze raw transcriptomics data from microarray and next-generation sequencing. In the R-ODAF, we also propose additional statistical steps to remove the number of false positives obtained from standard data analysis pipelines for RNA-sequencing. We illustrate the added value of R-ODAF, compared to a standard workflow, using a typical toxicogenomics dataset of hepatocytes exposed to paracetamol.
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14
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Nault R, Saha S, Bhattacharya S, Dodson J, Sinha S, Maiti T, Zacharewski T. Benchmarking of a Bayesian single cell RNAseq differential gene expression test for dose-response study designs. Nucleic Acids Res 2022; 50:e48. [PMID: 35061903 PMCID: PMC9071439 DOI: 10.1093/nar/gkac019] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 12/15/2021] [Accepted: 01/07/2022] [Indexed: 12/04/2022] Open
Abstract
The application of single-cell RNA sequencing (scRNAseq) for the evaluation of chemicals, drugs, and food contaminants presents the opportunity to consider cellular heterogeneity in pharmacological and toxicological responses. Current differential gene expression analysis (DGEA) methods focus primarily on two group comparisons, not multi-group dose-response study designs used in safety assessments. To benchmark DGEA methods for dose-response scRNAseq experiments, we proposed a multiplicity corrected Bayesian testing approach and compare it against 8 other methods including two frequentist fit-for-purpose tests using simulated and experimental data. Our Bayesian test method outperformed all other tests for a broad range of accuracy metrics including control of false positive error rates. Most notable, the fit-for-purpose and standard multiple group DGEA methods were superior to the two group scRNAseq methods for dose-response study designs. Collectively, our benchmarking of DGEA methods demonstrates the importance in considering study design when determining the most appropriate test methods.
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Affiliation(s)
| | | | - Sudin Bhattacharya
- Biomedical Engineering Department, Pharmacology & Toxicology, Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI 48824, USA
| | - Jack Dodson
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Samiran Sinha
- Department of Statistics, Texas A&M University, College Station, TX 77843, USA
| | - Tapabrata Maiti
- To whom correspondence should be addressed. Tel: +1 517 353 3233; Fax: +1 517 353 9334;
| | - Tim Zacharewski
- Correspondence may also be addressed to Tim Zacharewski. Tel: +1 517 355 1607; Fax: +1 517 353 9334;
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15
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Mao T, Wang H, Peng Z, Ni T, Jia T, Lei R, Liu W. Determination of Hexabromocyclododecane in Expanded Polystyrene and Extruded Polystyrene Foam by Gas Chromatography-Mass Spectrometry. Molecules 2021; 26:molecules26237143. [PMID: 34885731 PMCID: PMC8659249 DOI: 10.3390/molecules26237143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 11/16/2021] [Accepted: 11/22/2021] [Indexed: 12/03/2022] Open
Abstract
A gas chromatography-mass spectrometry (GC/MS) method for the determination of hexabromocyclododecane (HBCD) in expanded polystyrene and extruded polystyrene foam (EPS/XPS) was developed. The EPS/XPS samples were ultrasonically extracted with acetone and the extracts were purified by filtration through a microporous membrane (0.22 μm) and solid-phase extraction. The samples were analyzed using a GC/MS using the selected ion monitoring mode. The ions 157, 319 and 401 were selected as the qualitative ions, while ion 239 was chosen as the quantitative ion. An HBCD standard working solution with a concentration range of 1.0–50.0 mg/L showed good linearity. The detection limit of HBCD was 0.5 mg/kg, meeting the LPC limit (<100 or 1000 mg/kg). Six laboratories were selected to verify the accuracy of the method, and 10 samples were tested. The interlaboratory relative standard deviation range was 3.68–9.80%. This method could play an important role in controlling HBCD contamination in EPS/XPS.
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Affiliation(s)
- Tianao Mao
- Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China;
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; (T.N.); (T.J.); (R.L.)
| | - Haoyang Wang
- Environmental Protection and Foreign Cooperation and Exchange Center of Ministry of Ecology and Environment, Beijing 100035, China;
- Correspondence: (H.W.); (W.L.); Tel.: +86-10-82268590 (H.W.); +86-10-62849356 (W.L.); Fax: +86-10-62849339 (W.L.)
| | - Zheng Peng
- Environmental Protection and Foreign Cooperation and Exchange Center of Ministry of Ecology and Environment, Beijing 100035, China;
| | - Taotao Ni
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; (T.N.); (T.J.); (R.L.)
| | - Tianqi Jia
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; (T.N.); (T.J.); (R.L.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Rongrong Lei
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; (T.N.); (T.J.); (R.L.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenbin Liu
- Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China;
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; (T.N.); (T.J.); (R.L.)
- University of Chinese Academy of Sciences, Beijing 100049, China
- Correspondence: (H.W.); (W.L.); Tel.: +86-10-82268590 (H.W.); +86-10-62849356 (W.L.); Fax: +86-10-62849339 (W.L.)
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16
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Barnett LMA, Kramer NE, Buerger AN, Love DH, Bisesi JH, Cummings BS. Transcriptomic Analysis of the Differential Nephrotoxicity of Diverse Brominated Flame Retardants in Rat and Human Renal Cells. Int J Mol Sci 2021; 22:ijms221810044. [PMID: 34576211 PMCID: PMC8465879 DOI: 10.3390/ijms221810044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 09/09/2021] [Accepted: 09/11/2021] [Indexed: 12/13/2022] Open
Abstract
Brominated flame retardants (BFRs) are environmentally persistent, are detected in humans, and some have been banned due to their potential toxicity. BFRs are developmental neurotoxicants and endocrine disruptors; however, few studies have explored their potential nephrotoxicity. We addressed this gap in the literature by determining the toxicity of three different BFRs (tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD), and tetrabromodiphenyl ether (BDE-47)) in rat (NRK 52E) and human (HK-2 and RPTEC) tubular epithelial cells. All compounds induced time- and concentration-dependent toxicity based on decreases in MTT staining and changes in cell and nuclear morphology. The toxicity of BFRs was chemical- and cell-dependent, and human cells were more susceptible to all three BFRs based on IC50s after 48 h exposure. BFRs also had chemical- and cell-dependent effects on apoptosis as measured by increases in annexin V and PI staining. The molecular mechanisms mediating this toxicity were investigated using RNA sequencing. Principal components analysis supported the hypothesis that BFRs induce different transcriptional changes in rat and human cells. Furthermore, BFRs only shared nine differentially expressed genes in rat cells and five in human cells. Gene set enrichment analysis demonstrated chemical- and cell-dependent effects; however, some commonalities were also observed. Namely, gene sets associated with extracellular matrix turnover, the coagulation cascade, and the SNS-related adrenal cortex response were enriched across all cell lines and BFR treatments. Taken together, these data support the hypothesis that BFRs induce differential toxicity in rat and human renal cell lines that is mediated by differential changes in gene expression.
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Affiliation(s)
| | - Naomi E Kramer
- Interdisciplinary Toxicology Program, University of Georgia, Athens, GA 30602, USA
| | - Amanda N Buerger
- Department of Environmental and Global Health and Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL 32611, USA
| | - Deirdre H Love
- Department of Environmental and Global Health and Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL 32611, USA
| | - Joseph H Bisesi
- Department of Environmental and Global Health and Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL 32611, USA
| | - Brian S Cummings
- Interdisciplinary Toxicology Program, University of Georgia, Athens, GA 30602, USA
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA 30602, USA
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17
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Dent MP, Vaillancourt E, Thomas RS, Carmichael PL, Ouedraogo G, Kojima H, Barroso J, Ansell J, Barton-Maclaren TS, Bennekou SH, Boekelheide K, Ezendam J, Field J, Fitzpatrick S, Hatao M, Kreiling R, Lorencini M, Mahony C, Montemayor B, Mazaro-Costa R, Oliveira J, Rogiers V, Smegal D, Taalman R, Tokura Y, Verma R, Willett C, Yang C. Paving the way for application of next generation risk assessment to safety decision-making for cosmetic ingredients. Regul Toxicol Pharmacol 2021; 125:105026. [PMID: 34389358 PMCID: PMC8547713 DOI: 10.1016/j.yrtph.2021.105026] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 07/22/2021] [Accepted: 08/06/2021] [Indexed: 11/30/2022]
Abstract
Next generation risk assessment (NGRA) is an exposure-led, hypothesis-driven approach that has the potential to support animal-free safety decision-making. However, significant effort is needed to develop and test the in vitro and in silico (computational) approaches that underpin NGRA to enable confident application in a regulatory context. A workshop was held in Montreal in 2019 to discuss where effort needs to be focussed and to agree on the steps needed to ensure safety decisions made on cosmetic ingredients are robust and protective. Workshop participants explored whether NGRA for cosmetic ingredients can be protective of human health, and reviewed examples of NGRA for cosmetic ingredients. From the limited examples available, it is clear that NGRA is still in its infancy, and further case studies are needed to determine whether safety decisions are sufficiently protective and not overly conservative. Seven areas were identified to help progress application of NGRA, including further investments in case studies that elaborate on scenarios frequently encountered by industry and regulators, including those where a ‘high risk’ conclusion would be expected. These will provide confidence that the tools and approaches can reliably discern differing levels of risk. Furthermore, frameworks to guide performance and reporting should be developed.
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Affiliation(s)
- M P Dent
- Unilever Safety and Environmental Assurance Centre, Sharnbrook, Bedfordshire, MK44 1LQ, UK.
| | - E Vaillancourt
- Health Canada, Healthy Environments and Consumer Safety Branch, 269 Laurier Ave. W., Ottawa, ON K1A 0K9, Canada.
| | - R S Thomas
- Center for Computational Toxicology and Exposure, U.S. Environmental Protection Agency, Research, Triangle Park, NC, 27711, USA.
| | - P L Carmichael
- Unilever Safety and Environmental Assurance Centre, Sharnbrook, Bedfordshire, MK44 1LQ, UK.
| | - G Ouedraogo
- l'Oréal, Research and Development, Paris, France.
| | - H Kojima
- National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, 158-8501, Tokyo, Japan.
| | - J Barroso
- European Commission, Joint Research Centre (JRC), Ispra, VA, Italy.
| | - J Ansell
- US Personal Care Products Council (PCPC), 1620 L St. NW, Suite 1200, Washington, D.C, 20036, USA.
| | - T S Barton-Maclaren
- Health Canada, Healthy Environments and Consumer Safety Branch, 269 Laurier Ave. W., Ottawa, ON K1A 0K9, Canada.
| | - S H Bennekou
- National Food Institute, Technical University of Denmark (DTU), Copenhagen, Denmark.
| | - K Boekelheide
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, USA.
| | - J Ezendam
- National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands.
| | - J Field
- Health Canada, Healthy Environments and Consumer Safety Branch, 269 Laurier Ave. W., Ottawa, ON K1A 0K9, Canada.
| | - S Fitzpatrick
- US Food and Drug Administration (US FDA), Center for Food Safety and Applied Nutrition (CFSAN), 5001 Campus Drive, College Park, MD, 20740, USA.
| | - M Hatao
- Japan Cosmetic Industry Association (JCIA), Metro City Kamiyacho 6F, 5-1-5, Toranomon, Minato-ku, Tokyo, 105-0001 Japan.
| | - R Kreiling
- Clariant Produkte (Deutschland) GmbH, Am Unisyspark 1, 65843, Sulzbach, Germany.
| | - M Lorencini
- Grupo Boticário, Research & Development, São José dos Pinhais, Brazil.
| | - C Mahony
- Procter & Gamble Technical Centres Ltd, Reading, RG2 0RX, UK.
| | - B Montemayor
- Cosmetics Alliance Canada, 420 Britannia Road East Suite 102, Mississauga, ON L4Z 3L5, Canada.
| | - R Mazaro-Costa
- Departament of Pharmacology, Universidade Federal de Goiás, Goiânia, GO, 74.690-900, Brazil.
| | - J Oliveira
- Brazilian Health Regulatory Agency (ANVISA), Gerência de Produtos de Higiene, Perfumes, Cosméticos e Saneantes, Setor de Indústria e Abastecimento (SIA), Trecho 5, Área Especial 57, CEP 71205-050, Brasília, DF, Brazil.
| | - V Rogiers
- Vrije Universiteit Brussel, Brussels, Belgium.
| | - D Smegal
- US Food and Drug Administration (US FDA), Center for Food Safety and Applied Nutrition (CFSAN), 5001 Campus Drive, College Park, MD, 20740, USA.
| | - R Taalman
- Cosmetics Europe, Avenue Herrmann-Debroux 40, 1160 Auderghem, Belgium.
| | - Y Tokura
- Allergic Disease Research Center, Chutoen General Medical Center, Kakegawa, Japan.
| | - R Verma
- US Food and Drug Administration (US FDA), Center for Food Safety and Applied Nutrition (CFSAN), 5001 Campus Drive, College Park, MD, 20740, USA.
| | - C Willett
- Humane Society International, Washington, DC, USA.
| | - C Yang
- Taiwan Cosmetic Industry Association (TWCIA), 8F No. 136, Bo'ai Rd., Zhongzheng Dist., Taipei City, 100, Taiwan, ROC.
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18
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Negi CK, Khan S, Dirven H, Bajard L, Bláha L. Flame Retardants-Mediated Interferon Signaling in the Pathogenesis of Nonalcoholic Fatty Liver Disease. Int J Mol Sci 2021; 22:ijms22084282. [PMID: 33924165 PMCID: PMC8074384 DOI: 10.3390/ijms22084282] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/14/2021] [Accepted: 04/16/2021] [Indexed: 02/06/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a growing concern worldwide, affecting 25% of the global population. NAFLD is a multifactorial disease with a broad spectrum of pathology includes steatosis, which gradually progresses to a more severe condition such as nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and eventually leads to hepatic cancer. Several risk factors, including exposure to environmental toxicants, are involved in the development and progression of NAFLD. Environmental factors may promote the development and progression of NAFLD by various biological alterations, including mitochondrial dysfunction, reactive oxygen species production, nuclear receptors dysregulation, and interference in inflammatory and immune-mediated signaling. Moreover, environmental contaminants can influence immune responses by impairing the immune system’s components and, ultimately, disease susceptibility. Flame retardants (FRs) are anthropogenic chemicals or mixtures that are being used to inhibit or delay the spread of fire. FRs have been employed in several household and outdoor products; therefore, human exposure is unavoidable. In this review, we summarized the potential mechanisms of FRs-associated immune and inflammatory signaling and their possible contribution to the development and progression of NAFLD, with an emphasis on FRs-mediated interferon signaling. Knowledge gaps are identified, and emerging pharmacotherapeutic molecules targeting the immune and inflammatory signaling for NAFLD are also discussed.
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Affiliation(s)
- Chander K. Negi
- Faculty of Science, RECETOX, Masaryk University, Kamenice 5, CZ62500 Brno, Czech Republic; (L.B.); (L.B.)
- Correspondence: or
| | - Sabbir Khan
- Department of Neuro-Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA;
| | - Hubert Dirven
- Department of Environmental Health, Section for Toxicology and Risk Assessment, Norwegian Institute of Public Health, 0456 Oslo, Norway;
| | - Lola Bajard
- Faculty of Science, RECETOX, Masaryk University, Kamenice 5, CZ62500 Brno, Czech Republic; (L.B.); (L.B.)
| | - Luděk Bláha
- Faculty of Science, RECETOX, Masaryk University, Kamenice 5, CZ62500 Brno, Czech Republic; (L.B.); (L.B.)
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19
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Schrenk D, Bignami M, Bodin L, Chipman JK, del Mazo J, Grasl‐Kraupp B, Hogstrand C, Hoogenboom L(R, Leblanc J, Nebbia CS, Nielsen E, Ntzani E, Petersen A, Sand S, Schwerdtle T, Wallace H, Benford D, Fürst P, Rose M, Ioannidou S, Nikolič M, Bordajandi LR, Vleminckx C. Update of the risk assessment of hexabromocyclododecanes (HBCDDs) in food. EFSA J 2021; 19:e06421. [PMID: 33732387 PMCID: PMC7938899 DOI: 10.2903/j.efsa.2021.6421] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The European Commission asked EFSA to update its 2011 risk assessment on hexabromocyclododecanes (HBCDDs) in food. HBCDDs, predominantly mixtures of the stereoisomers α-, β- and γ-HBCDD, were widely used additive flame retardants. Concern has been raised because of the occurrence of HBCDDs in the environment, food and in humans. Main targets for toxicity are neurodevelopment, the liver, thyroid hormone homeostasis and the reproductive and immune systems. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour in mice can be considered the critical effects. Based on effects on spontaneous behaviour in mice, the Panel identified a lowest observed adverse effect level (LOAEL) of 0.9 mg/kg body weight (bw) as the Reference Point, corresponding to a body burden of 0.75 mg/kg bw. The chronic intake that would lead to the same body burden in humans was calculated to be 2.35 μg/kg bw per day. The derivation of a health-based guidance value (HBGV) was not considered appropriate. Instead, the margin of exposure (MOE) approach was applied to assess possible health concerns. Over 6,000 analytical results for HBCDDs in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary LB exposure to HBCDDs were fish meat, eggs, livestock meat and poultry. The CONTAM Panel concluded that the resulting MOE values support the conclusion that current dietary exposure to HBCDDs across European countries does not raise a health concern. An exception is breastfed infants with high milk consumption, for which the lowest MOE values may raise a health concern.
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20
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Ding Y, Xu T, Mao G, Chen Y, Qiu X, Yang L, Zhao T, Xu X, Feng W, Wu X. Di-(2-ethylhexyl) phthalate-induced hepatotoxicity exacerbated type 2 diabetes mellitus (T2DM) in female pubertal T2DM mice. Food Chem Toxicol 2021; 149:112003. [PMID: 33484791 DOI: 10.1016/j.fct.2021.112003] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 01/10/2021] [Accepted: 01/14/2021] [Indexed: 12/25/2022]
Abstract
Di-(2-ethylhexyl) phthalate (DEHP), one of the most common plasticizers, is closely associated with a high prevalence of pubertal type 2 diabetes mellitus (T2DM). Numerous studies have indicated that DEHP-induced metabolic toxicity exhibits sex differences. In this study, the sex differences in the effect of DEHP on pubertal T2DM (P-T2DM) mice, the susceptibility of female P-T2DM mice to DEHP-induced metabolic toxicity, and the underlying mechanisms were investigated. DEHP exposure exacerbated metabolic disorders in female P-T2DM mice. Factorial analysis showed that female P-T2DM mice were more sensitive to DEHP exposure than female normal mice and male P-T2DM mice. It was determined by integrated biomarker response results that female P-T2DM mice had higher risks of developing T2DM, metabolic disorders, cardiovascular events and hepatotoxicity than male P-T2DM mice. Moreover, hepatic transcriptome analysis emphasized the effects of DEHP on the expression of oxidative injury- and metabolic function-related genes. Western blotting indicated that DEHP activated Jun-N-terminal kinase (JNK) and impaired insulin sensitivity in the liver, which were the main causes of DEHP-exacerbated metabolic abnormalities in P-T2DM mice. Our study revealed that compared with normal mice and male P-T2DM mice, female P-T2DM mice tend to suffer from increased DEHP-induced metabolic toxicity, which was primarily attributed to hepatotoxicity.
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Affiliation(s)
- Yangyang Ding
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Tong Xu
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Guanghua Mao
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Yao Chen
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, China; Institute of Environmental health and Ecological Security, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Xuchun Qiu
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, China; Institute of Environmental health and Ecological Security, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Liuqing Yang
- School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Ting Zhao
- School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Xiaoxiao Xu
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Weiwei Feng
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, China; Institute of Environmental health and Ecological Security, Jiangsu University, Zhenjiang, Jiangsu, China.
| | - Xiangyang Wu
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, China; Institute of Environmental health and Ecological Security, Jiangsu University, Zhenjiang, Jiangsu, China.
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21
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Dai W, Tang T, Dai Z, Shi D, Mo L, Zhang Y. Probing the Mechanism of Hepatotoxicity of Hexabromocyclododecanes through Toxicological Network Analysis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:15235-15245. [PMID: 33190479 DOI: 10.1021/acs.est.0c03998] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The prediction and mechanism analysis of hepatotoxicity of contaminants, because of their various phenotypes and complex mechanisms, is still a key problem in environmental research. We applied a toxicological network analysis method to predict the hepatotoxicity of three hexabromocyclododecane (HBCD) diastereoisomers (α-HBCD, β-HBCD, and γ-HBCD) and explore their potential mechanisms. First, we collected the hepatotoxicity related genes and found that those genes were significantly localized in the human interactome. Therefore, these genes form a disease module of hepatotoxicity. We also collected targets of α-, β-, and γ-HBCD and found that their targets overlap with the hepatotoxicity disease module. Then, we trained a model to predict hepatotoxicity of three HBCD diastereoisomers based on the relationship between the hepatotoxicity disease module and targets of compounds. We found that 593 genes were significantly located in the hepatotoxicity disease module (Z = 11.9, p < 0.001) involved in oxidative stress, cellular immunity, and proliferation, and the accuracy of hepatotoxicity prediction of HBCD was 0.7095 ± 0.0193 and the recall score was 0.8355 ± 0.0352. HBCD mainly affects the core disease module genes to mediate the adenosine monophosphate-activated kinase, p38MAPK, PI3K/Akt, and TNFα pathways to regulate the immune reaction and inflammation. HBCD also induces the secretion of IL6 and STAT3 to lead hepatotoxicity by regulating NR3C1. This approach is transferable to other toxicity research studies of environmental pollutants.
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Affiliation(s)
- Weina Dai
- Chongqing Research Center for Pharmaceutical Engineering, College of Pharmacy, Chongqing Medical University, Chongqing 400016, China
| | - Tiantian Tang
- Chongqing Research Center for Pharmaceutical Engineering, College of Pharmacy, Chongqing Medical University, Chongqing 400016, China
| | - Zhenghua Dai
- Chongqing Research Center for Pharmaceutical Engineering, College of Pharmacy, Chongqing Medical University, Chongqing 400016, China
- Chongqing Academy of Metrology and Quality Inspection, Chongqing 401123, China
| | - Da Shi
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California 92093, United States
| | - Lingyun Mo
- The Guangxi Key Laboratory of Theory and Technology for Environmental Pollution Control, College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541004, China
- Technical Innovation Center for Mine Geological Environment Restoration Engineering in Shishan Area of South China, Ministry of Natural Resources, Nanning 530028, China
| | - Yonghong Zhang
- Chongqing Research Center for Pharmaceutical Engineering, College of Pharmacy, Chongqing Medical University, Chongqing 400016, China
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22
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Johnson KJ, Auerbach SS, Costa E. A Rat Liver Transcriptomic Point of Departure Predicts a Prospective Liver or Non-liver Apical Point of Departure. Toxicol Sci 2020; 176:86-102. [PMID: 32384157 PMCID: PMC7357187 DOI: 10.1093/toxsci/kfaa062] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Identifying a toxicity point of departure (POD) is a required step in human health risk characterization of crop protection molecules, and this POD has historically been derived from apical endpoints across a battery of animal-based toxicology studies. Using rat transcriptome and apical data for 79 molecules obtained from Open TG-GATES (Toxicogenomics Project-Genomics Assisted Toxicity Evaluation System) (632 datasets), the hypothesis was tested that a short-term exposure, transcriptome-based liver biological effect POD (BEPOD) could estimate a longer-term exposure "systemic" apical endpoint POD. Apical endpoints considered were body weight, clinical observation, kidney weight and histopathology and liver weight and histopathology. A BMDExpress algorithm using Gene Ontology Biological Process gene sets was optimized to derive a liver BEPOD most predictive of a systemic apical POD. Liver BEPODs were stable from 3 h to 29 days of exposure; the median fold difference of the 29-day BEPOD to BEPODs from earlier time points was approximately 1 (range: 0.7-1.1). Strong positive correlation (Pearson R = 0.86) and predictive accuracy (root mean square difference = 0.41) were observed between a concurrent (29 days) liver BEPOD and the systemic apical POD. Similar Pearson R and root mean square difference values were observed for comparisons between a 29-day systemic apical POD and liver BEPODs derived from 3 h to 15 days of exposure. These data across 79 molecules suggest that a longer-term exposure study apical POD from liver and non-liver compartments can be estimated using a liver BEPOD derived from an acute or subacute exposure study.
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Affiliation(s)
- Kamin J Johnson
- Predictive Safety Center, Corteva Agriscience, Indianapolis, Indiana
| | - Scott S Auerbach
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - Eduardo Costa
- Data Science and Informatics, Corteva Agriscience, Mogi Mirim, Sao Paulo, Brazil
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23
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Nicolaidou V, Koufaris C. Application of transcriptomic and microRNA profiling in the evaluation of potential liver carcinogens. Toxicol Ind Health 2020; 36:386-397. [PMID: 32419640 DOI: 10.1177/0748233720922710] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Hepatocarcinogens are agents that increase the incidence of liver cancer in exposed animals or humans. It is now established that carcinogenic exposures have a widespread impact on the transcriptome, inducing both adaptive and adverse changes in the activities of genes and pathways. Chemical hepatocarcinogens have also been shown to affect expression of microRNA (miRNA), the evolutionarily conserved noncoding RNA that regulates gene expression posttranscriptionally. Considerable effort has been invested into examining the involvement of mRNA in chemical hepatocarcinogenesis and their potential usage for the classification and prediction of new chemical entities. For miRNA, there has been an increasing number of studies reported over the past decade, although not to the same degree as for transcriptomic studies. Current data suggest that it is unlikely that any gene or miRNA signature associated with short-term carcinogen exposure can replace the rodent bioassay. In this review, we discuss the application of transcriptomic and miRNA profiles to increase mechanistic understanding of chemical carcinogens and to aid in their classification.
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Affiliation(s)
- Vicky Nicolaidou
- Department of Life and Health Sciences, University of Nicosia, Nicosia, Cyprus
| | - Costas Koufaris
- Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus
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24
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Nault R, Bals B, Teymouri F, Black MB, Andersen ME, McMullen PD, Krishnan S, Kuravadi N, Paul N, Kumar S, Kannan K, Jayachandra KC, Alagappan L, Patel BD, Bogen KT, Gollapudi BB, Klaunig JE, Zacharewski TR, Bringi V. A toxicogenomic approach for the risk assessment of the food contaminant acetamide. Toxicol Appl Pharmacol 2020; 388:114872. [PMID: 31881176 PMCID: PMC7014822 DOI: 10.1016/j.taap.2019.114872] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Revised: 12/10/2019] [Accepted: 12/20/2019] [Indexed: 12/26/2022]
Abstract
Acetamide (CAS 60-35-5) is detected in common foods. Chronic rodent bioassays led to its classification as a group 2B possible human carcinogen due to the induction of liver tumors in rats. We used a toxicogenomics approach in Wistar rats gavaged daily for 7 or 28 days at doses of 300 to 1500 mg/kg/day (mkd) to determine a point of departure (POD) and investigate its mode of action (MoA). Ki67 labeling was increased at doses ≥750 mkd up to 3.3-fold representing the most sensitive apical endpoint. Differential gene expression analysis by RNA-Seq identified 1110 and 1814 differentially expressed genes in male and female rats, respectively, following 28 days of treatment. Down-regulated genes were associated with lipid metabolism while up-regulated genes included cell signaling, immune response, and cell cycle functions. Benchmark dose (BMD) modeling of the Ki67 labeling index determined the BMD10 lower confidence limit (BMDL10) as 190 mkd. Transcriptional BMD modeling revealed excellent concordance between transcriptional POD and apical endpoints. Collectively, these results indicate that acetamide is most likely acting through a mitogenic MoA, though specific key initiating molecular events could not be elucidated. A POD value of 190 mkd determined for cell proliferation is suggested for risk assessment purposes.
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Affiliation(s)
- Rance Nault
- Institute for Integrative Toxicology, Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, United States of America
| | - Bryan Bals
- Michigan Biotechnology Institute, Lansing, MI, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Tim R Zacharewski
- Institute for Integrative Toxicology, Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, United States of America
| | - Venkataraman Bringi
- Chemical Engineering & Materials Science, Michigan State University, East Lansing, MI, USA.
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