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Klaunig JE, Bevan C, Gollapudi B. Assessment of the mode of action of perchloroethylene-induced mouse liver tumors. Toxicol Ind Health 2024; 40:272-291. [PMID: 38523547 DOI: 10.1177/07482337241240188] [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] [Indexed: 03/26/2024]
Abstract
Perchloroethylene (PCE) is used as a solvent and chemical intermediate. Following chronic inhalation exposure, PCE selectively induced liver tumors in mice. Understanding the mode of action (MOA) for PCE carcinogenesis in mice is important in defining its possible human cancer risk. The proposed MOA is based on the extensive examination of the peer-reviewed studies that have assessed the mouse liver effects of PCE and its major oxidative metabolite trichloroacetic acid (TCA). Similar to PCE, TCA has also been demonstrated to liver tumors selectively in mice following chronic exposure. The Key Events (KE) of the proposed PCE MOA involve oxidative metabolism of PCE to TCA [KE 1]; activation of the peroxisome proliferator-activated receptor alpha (PPARα) [KE 2]; alteration in hepatic gene expression including cell growth pathways [KE 3]; increase in cell proliferation [KE 4]; selective clonal expansion of hepatic preneoplastic foci [KE 5]; and formation of hepatic neoplasms [KE 6]. The scientific evidence supporting the PPARα MOA for PCE is strong and satisfies the requirements for a MOA analysis. The PPARα liver tumor MOA in rodents has been demonstrated not to occur in humans; thus, human liver cancer risk to PCE is not likely.
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Affiliation(s)
- James E Klaunig
- School of Public Health, Indiana University, Bloomington, IN, USA
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2
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Dalaijamts C, Cichocki JA, Luo YS, Rusyn I, Chiu WA. Quantitative Characterization of Population-Wide Tissue- and Metabolite-Specific Variability in Perchloroethylene Toxicokinetics in Male Mice. Toxicol Sci 2021; 182:168-182. [PMID: 33988684 DOI: 10.1093/toxsci/kfab057] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Quantification of interindividual variability is a continuing challenge in risk assessment, particularly for compounds with complex metabolism and multi-organ toxicity. Toxicokinetic variability for perchloroethylene (perc) was previously characterized across 3 mouse strains and in 1 mouse strain with various degrees of liver steatosis. To further characterize the role of genetic variability in toxicokinetics of perc, we applied Bayesian population physiologically based pharmacokinetic (PBPK) modeling to the data on perc and metabolites in blood/plasma and tissues of male mice from 45 inbred strains from the Collaborative Cross (CC) mouse population. After identifying the most influential PBPK parameters based on global sensitivity analysis, we fit the model with a hierarchical Bayesian population analysis using Markov chain Monte Carlo simulation. We found that the data from 3 commonly used strains were not representative of the full range of variability in perc and metabolite blood/plasma and tissue concentrations across the CC population. Using interstrain variability as a surrogate for human interindividual variability, we calculated dose-dependent, chemical-, and tissue-specific toxicokinetic variability factors (TKVFs) as candidate science-based replacements for the default uncertainty factor for human toxicokinetic variability of 100.5. We found that toxicokinetic variability factors for glutathione conjugation metabolites of perc showed the greatest variability, often exceeding the default, whereas those for oxidative metabolites and perc itself were generally less than the default. Overall, we demonstrate how a combination of a population-based mouse model such as the CC with Bayesian population PBPK modeling can reduce uncertainty in human toxicokinetic variability and increase accuracy and precision in quantitative risk assessment.
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Affiliation(s)
- Chimeddulam Dalaijamts
- Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, Texas 77843-4458, USA.,Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4458, USA
| | - Joseph A Cichocki
- Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, Texas 77843-4458, USA.,Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4458, USA
| | - Yu-Syuan Luo
- Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, Texas 77843-4458, USA.,Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4458, USA
| | - Ivan Rusyn
- Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, Texas 77843-4458, USA.,Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4458, USA
| | - Weihsueh A Chiu
- Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, Texas 77843-4458, USA.,Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4458, USA
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3
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Cichocki JA, Luo YS, Furuya S, Venkatratnam A, Konganti K, Chiu WA, Threadgill DW, Pogribny IP, Rusyn I. Modulation of Tetrachloroethylene-Associated Kidney Effects by Nonalcoholic Fatty Liver or Steatohepatitis in Male C57BL/6J Mice. Toxicol Sci 2019; 167:126-137. [PMID: 30202895 DOI: 10.1093/toxsci/kfy223] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Accounting for genetic and other (eg, underlying disease states) factors that may lead to inter-individual variability in susceptibility to xenobiotic-induced injury is a challenge in human health assessments. A previous study demonstrated that nonalcoholic fatty liver disease (NAFLD), one of the common underlying disease states, enhances tetrachloroethylene (PERC)-associated hepatotoxicity in mice. Interestingly, NAFLD resulted in a decrease in metabolism of PERC to nephrotoxic glutathione conjugates; we therefore hypothesized that NAFLD would protect against PERC-associated nephrotoxicity. Male C57BL/6J mice were fed a low-fat (LFD), high-fat (31% fat, HFD), or high-fat methionine/choline/folate-deficient (31% fat, MCD) diets. After 8 weeks mice were administered either a single dose of PERC (300 mg/kg i.g.) and euthanized at 1-36 h post dose, or five daily doses of PERC (300 mg/kg/d i.g.) and euthanized 4 h after last dose. Relative to LFD-fed mice, HFD- or MCD-fed mice exhibited decreased PERC concentrations and increased trichloroacetate (TCA) in kidneys. S-(1,2,2-trichlorovinyl)glutathione (TCVG), S-(1,2,2-trichlorovinyl)-l-cysteine (TCVC), and N-acetyl-S-(1,2,2,-trichlorovinyl)-l-cysteine (NAcTCVC) were also significantly lower in kidney and urine of HFD- or MCD-fed mice compared with LFD-fed mice. Despite differences in levels of nephrotoxic PERC metabolites in kidney, LFD- and MCD-fed mice demonstrated similar degree of nephrotoxicity. However, HFD-fed mice were less sensitive to PERC-induced nephrotoxicity. Thus, whereas both MCD- and HFD-induced fatty liver reduced the delivered dose of nephrotoxic PERC metabolites to the kidney, only HFD was protective against PERC-induced nephrotoxicity, possibly due to greater toxicodynamic sensitivity induced by methyl and choline deficiency. These results therefore demonstrate that pre-existing disease conditions can lead to a complex interplay of toxicokinetic and toxicodynamic changes that modulate susceptibility to the toxicity of xenobiotics.
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Affiliation(s)
| | - Yu-Syuan Luo
- Department of Veterinary Integrative Biosciences
| | | | | | | | | | - David W Threadgill
- Texas A&M Institute for Genome Sciences and Society.,Department of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas 77843
| | - Igor P Pogribny
- National Center for Toxicological Research, US FDA, Jefferson, Arkansas 72079
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences
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4
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Wahlang B, Jin J, Beier JI, Hardesty JE, Daly EF, Schnegelberger RD, Falkner KC, Prough RA, Kirpich IA, Cave MC. Mechanisms of Environmental Contributions to Fatty Liver Disease. Curr Environ Health Rep 2019; 6:80-94. [PMID: 31134516 PMCID: PMC6698418 DOI: 10.1007/s40572-019-00232-w] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE Fatty liver disease (FLD) affects over 25% of the global population and may lead to liver-related mortality due to cirrhosis and liver cancer. FLD caused by occupational and environmental chemical exposures is termed "toxicant-associated steatohepatitis" (TASH). The current review addresses the scientific progress made in the mechanistic understanding of TASH since its initial description in 2010. RECENT FINDINGS Recently discovered modes of actions for volatile organic compounds and persistent organic pollutants include the following: (i) the endocrine-, metabolism-, and signaling-disrupting chemical hypotheses; (ii) chemical-nutrient interactions and the "two-hit" hypothesis. These key hypotheses were then reviewed in the context of the steatosis adverse outcome pathway (AOP) proposed by the US Environmental Protection Agency. The conceptual understanding of the contribution of environmental exposures to FLD has progressed significantly. However, because this is a new research area, more studies including mechanistic human data are required to address current knowledge gaps.
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Affiliation(s)
- Banrida Wahlang
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Louisville School of Medicine, Louisville, KY, 40202, USA
- University of Louisville Superfund Research Center, University of Louisville, Louisville, KY, 40202, USA
| | - Jian Jin
- Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY, 40202, USA
| | - Juliane I Beier
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, PA, 15213, USA
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Josiah E Hardesty
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Louisville School of Medicine, Louisville, KY, 40202, USA
| | - Erica F Daly
- Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY, 40202, USA
| | - Regina D Schnegelberger
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - K Cameron Falkner
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Louisville School of Medicine, Louisville, KY, 40202, USA
| | - Russell A Prough
- Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY, 40202, USA
| | - Irina A Kirpich
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Louisville School of Medicine, Louisville, KY, 40202, USA
- Hepatobiology & Toxicology COBRE Center, University of Louisville School of Medicine, Louisville, KY, 40202, USA
- University of Louisville Alcohol Research Center, University of Louisville, Louisville, KY, 40202, USA
| | - Matthew C Cave
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Louisville School of Medicine, Louisville, KY, 40202, USA.
- University of Louisville Superfund Research Center, University of Louisville, Louisville, KY, 40202, USA.
- Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY, 40202, USA.
- Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY, 40202, USA.
- Hepatobiology & Toxicology COBRE Center, University of Louisville School of Medicine, Louisville, KY, 40202, USA.
- University of Louisville Alcohol Research Center, University of Louisville, Louisville, KY, 40202, USA.
- The Robley Rex Veterans Affairs Medical Center, Louisville, KY, 40206, USA.
- The Jewish Hospital Liver Transplant Program, Louisville, KY, 40202, USA.
- Kosair Charities Clinical & Translational Research Building, 505 South Hancock Street, Louisville, KY, 40202, USA.
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5
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Luo YS, Furuya S, Soldatov VY, Kosyk O, Yoo HS, Fukushima H, Lewis L, Iwata Y, Rusyn I. Metabolism and Toxicity of Trichloroethylene and Tetrachloroethylene in Cytochrome P450 2E1 Knockout and Humanized Transgenic Mice. Toxicol Sci 2019; 164:489-500. [PMID: 29897530 DOI: 10.1093/toxsci/kfy099] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Trichloroethylene (TCE) and tetrachloroethylene (PCE) are structurally similar olefins that can cause liver and kidney toxicity. Adverse effects of these chemicals are associated with metabolism to oxidative and glutathione conjugation moieties. It is thought that CYP2E1 is crucial to the oxidative metabolism of TCE and PCE, and may also play a role in formation of nephrotoxic metabolites; however, inter-species and inter-individual differences in contribution of CYP2E1 to metabolism and toxicity are not well understood. Therefore, the role of CYP2E1 in metabolism and toxic effects of TCE and PCE was investigated using male and female wild-type [129S1/SvlmJ], Cyp2e1(-/-), and humanized Cyp2e1 [hCYP2E1] mice. To fill in existing gaps in our knowledge, we conducted a toxicokinetic study of TCE (600 mg/kg, single dose, i.g.) and a subacute study of PCE (500 mg/kg/day, 5 days, i.g.) in 3 strains. Liver and kidney tissues were subject to profiling of oxidative and glutathione conjugation metabolites of TCE and PCE, as well as toxicity endpoints. The amounts of trichloroacetic acid formed in the liver was hCYP2E1≈ 129S1/SvlmJ > Cyp2e1(-/-) for both TCE and PCE; levels in males were about 2-fold higher than in females. Interestingly, 2- to 3-fold higher levels of conjugation metabolites were observed in TCE-treated Cyp2e1(-/-) mice. PCE induced lipid accumulation only in liver of 129S1/SvlmJ mice. In the kidney, PCE exposure resulted in acute proximal tubule injury in both sexes in all strains (hCYP2E1 ≈ 129S1/SvlmJ > Cyp2e1(-/-)). In conclusion, our results demonstrate that CYP2E1 is an important, but not exclusive actor in the oxidative metabolism and toxicity of TCE and PCE.
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Affiliation(s)
- Yu-Syuan Luo
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
| | - Shinji Furuya
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
| | - Valerie Y Soldatov
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Oksana Kosyk
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Hong Sik Yoo
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Hisataka Fukushima
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
| | - Lauren Lewis
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
| | - Yasuhiro Iwata
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
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6
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Lang AL, Beier JI. Interaction of volatile organic compounds and underlying liver disease: a new paradigm for risk. Biol Chem 2019; 399:1237-1248. [PMID: 29924722 DOI: 10.1515/hsz-2017-0324] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 06/14/2018] [Indexed: 01/07/2023]
Abstract
Occupational and environmental exposures to industrial chemicals are known to cause hepatotoxicity and liver injury, in humans and in animal models. Historically, research has focused on severe acute liver injury (e.g. fulminant liver failure) or endstage diseases (e.g. cirrhosis and HCC). However, it has become recently recognized that toxicants can cause more subtle changes to the liver. For example, toxicant-associated steatohepatitis, characterized by hepatic steatosis, and inflammation, was recently recognized in an occupational cohort exposed to vinyl chloride. At high occupational levels, toxicants are sufficient to cause liver damage and disease even in healthy subjects with no comorbidities for liver injury. However, it is still largely unknown how exposure to toxicants initiate and possibly more importantly exacerbate liver disease, when combined with other factors, such as underlying non-alcoholic fatty liver disease caused by poor diet and/or obesity. With better understanding of the mechanism(s) and risk factors that mediate the initiation and progression of toxicant-induced liver disease, rational targeted therapy can be developed to better predict risk, as well as to treat or prevent this disease. The purpose of this review is to summarize established and proposed mechanisms of volatile organic compound-induced liver injury and to highlight key signaling events known or hypothesized to mediate these effects.
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Affiliation(s)
- Anna L Lang
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY 40292, USA.,Hepatobiology and Toxicology Program, University of Louisville, Louisville, KY 40292, USA.,University of Louisville Alcohol Research Center, University of Louisville Health Sciences Center, Louisville, KY 40292, USA
| | - Juliane I Beier
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY 40292, USA.,Hepatobiology and Toxicology Program, University of Louisville, Louisville, KY 40292, USA.,University of Louisville Alcohol Research Center, University of Louisville Health Sciences Center, Louisville, KY 40292, USA.,Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, PA 15213, USA
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7
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Luo YS, Hsieh NH, Soldatow VY, Chiu WA, Rusyn I. Comparative analysis of metabolism of trichloroethylene and tetrachloroethylene among mouse tissues and strains. Toxicology 2018; 409:33-43. [PMID: 30053492 PMCID: PMC6186498 DOI: 10.1016/j.tox.2018.07.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 07/22/2018] [Accepted: 07/23/2018] [Indexed: 11/21/2022]
Abstract
Trichloroethylene (TCE) and tetrachloroethylene (PCE) are structurally similar chemicals that are metabolized through oxidation and glutathione conjugation pathways. Both chemicals have been shown to elicit liver and kidney toxicity in rodents and humans; however, TCE has been studied much more extensively in terms of both metabolism and toxicity. Despite their qualitative similarities, quantitative comparison of tissue- and strain-specific metabolism of TCE and PCE has not been performed. To fill this gap, we conducted a comparative toxicokinetic study where equimolar single oral doses of TCE (800 mg/kg) or PCE (1000 mg/kg) were administered to male mice of C57BL/6J, B6C3F1/J, and NZW/LacJ strains. Samples of liver, kidney, serum, brain, and lung were obtained for up to 36 h after dosing. For each tissue, concentrations of parent compounds, as well as their oxidative and glutathione conjugation metabolites were measured and concentration-time profiles constructed. A multi-compartment toxicokinetic model was developed to quantitatively compare TCE and PCE metabolism. As expected, the flux through oxidation metabolism pathway predominated over that through conjugation across all mouse strains examined, it is 1,200-3,800 fold higher for TCE and 26-34 fold higher for PCE. However, the flux through glutathione conjugation, albeit a minor metabolic pathway, was 21-fold higher for PCE as compared to TCE. The degree of inter-strain variability was greatest for oxidative metabolites in TCE-treated and for glutathione conjugation metabolites in PCE-treated mice. This study provides critical data for quantitative comparisons of TCE and PCE metabolism, and may explain the differences in organ-specific toxicity between these structurally similar chemicals.
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Affiliation(s)
- Yu-Syuan Luo
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Nan-Hung Hsieh
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Valerie Y Soldatow
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, NC, USA
| | - Weihsueh A Chiu
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA.
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Dalaijamts C, Cichocki JA, Luo YS, Rusyn I, Chiu WA. Incorporation of the glutathione conjugation pathway in an updated physiologically-based pharmacokinetic model for perchloroethylene in mice. Toxicol Appl Pharmacol 2018; 352:142-152. [PMID: 29857080 PMCID: PMC6051410 DOI: 10.1016/j.taap.2018.05.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 05/16/2018] [Accepted: 05/25/2018] [Indexed: 12/13/2022]
Abstract
BACKGROUND Perchloroethylene (perc) induced target organ toxicity has been associated with tissue-specific metabolic pathways. Previous physiologically-based pharmacokinetic (PBPK) modeling of perc accurately predicted oxidative metabolites but suggested the need to better characterize glutathione (GSH) conjugation as well as toxicokinetic uncertainty and variability. OBJECTIVES We updated the previously published "harmonized" perc PBPK model in mice to better characterize GSH conjugation metabolism as well as the uncertainty and variability of perc toxicokinetics. METHODS The updated PBPK model includes expanded models for perc and its oxidative metabolite trichloroacetic acid (TCA), and physiologically-based sub-models for conjugative metabolites. Previously compiled mouse kinetic data in B6C3F1 and Swiss-Webster mice were augmented to include data from a recent study in male C57BL/6J mice that measured perc and metabolites in serum and multiple tissues. Hierarchical Bayesian population analysis using Markov chain Monte Carlo was conducted to characterize uncertainty and inter-strain variability in perc metabolism. RESULTS The updated model fit the data as well or better than the previously published "harmonized" PBPK model. Tissue dosimetry for both oxidative and conjugative metabolites was successfully predicted across the three strains of mice, with estimated residuals errors of 2-fold for majority of data. Inter-strain variability across three strains was evident for oxidative metabolism; GSH conjugation data were only available for one strain. CONCLUSIONS This updated PBPK model fills a critical data gap in quantitative risk assessment by predicting the internal dosimetry of perc and its oxidative and GSH conjugation metabolites and lays the groundwork for future studies to better characterize toxicokinetic variability.
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Affiliation(s)
- Chimeddulam Dalaijamts
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Joseph A Cichocki
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Yu-Syuan Luo
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Weihsueh A Chiu
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA.
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9
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Zhou YH, Cichocki JA, Soldatow VY, Scholl EH, Gallins PJ, Jima D, Yoo HS, Chiu WA, Wright FA, Rusyn I. Editor's Highlight: Comparative Dose-Response Analysis of Liver and Kidney Transcriptomic Effects of Trichloroethylene and Tetrachloroethylene in B6C3F1 Mouse. Toxicol Sci 2017; 160:95-110. [PMID: 28973375 PMCID: PMC5837274 DOI: 10.1093/toxsci/kfx165] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Trichloroethylene (TCE) and tetrachloroethylene (PCE) are ubiquitous environmental contaminants and occupational health hazards. Recent health assessments of these agents identified several critical data gaps, including lack of comparative analysis of their effects. This study examined liver and kidney effects of TCE and PCE in a dose-response study design. Equimolar doses of TCE (24, 80, 240, and 800 mg/kg) or PCE (30, 100, 300, and 1000 mg/kg) were administered by gavage in aqueous vehicle to male B6C3F1/J mice. Tissues were collected 24 h after exposure. Trichloroacetic acid (TCA), a major oxidative metabolite of both compounds, was measured and RNA sequencing was performed. PCE had a stronger effect on liver and kidney transcriptomes, as well as greater concentrations of TCA. Most dose-responsive pathways were common among chemicals/tissues, with the strongest effect on peroxisomal β-oxidation. Effects on liver and kidney mitochondria-related pathways were notably unique to PCE. We performed dose-response modeling of the transcriptomic data and compared the resulting points of departure (PODs) to those for apical endpoints derived from long-term studies with these chemicals in rats, mice, and humans, converting to human equivalent doses using tissue-specific dosimetry models. Tissue-specific acute transcriptional effects of TCE and PCE occurred at human equivalent doses comparable to those for apical effects. These data are relevant for human health assessments of TCE and PCE as they provide data for dose-response analysis of the toxicity mechanisms. Additionally, they provide further evidence that transcriptomic data can be useful surrogates for in vivo PODs, especially when toxicokinetic differences are taken into account.
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Affiliation(s)
- Yi-Hui Zhou
- Department of Biological Sciences
- Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina
| | - Joseph A. Cichocki
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas
| | - Valerie Y. Soldatow
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina
| | - Elizabeth H. Scholl
- Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina
| | - Paul J. Gallins
- Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina
| | - Dereje Jima
- Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina
| | - Hong-Sik Yoo
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina
| | - Weihsueh A. Chiu
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas
| | - Fred A. Wright
- Department of Biological Sciences
- Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina
- Department of Statistics, North Carolina State University, Raleigh, North Carolina
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas
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10
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Cichocki JA, Furuya S, Luo YS, Iwata Y, Konganti K, Chiu WA, Threadgill DW, Pogribny IP, Rusyn I. Nonalcoholic Fatty Liver Disease Is a Susceptibility Factor for Perchloroethylene-Induced Liver Effects in Mice. Toxicol Sci 2017; 159:102-113. [PMID: 28903486 PMCID: PMC5837635 DOI: 10.1093/toxsci/kfx120] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is the most prevalent pathological liver condition in developed countries. NAFLD results in severe alterations in liver function, including xenobiotic metabolism. Perchloroethylene (PERC) is a ubiquitous environmental pollutant, a known hepatotoxicant in rodents, and a probable human carcinogen. It is known that PERC disposition and metabolism are affected by NAFLD in mice; here, we examined how NAFLD changes PERC-associated liver effects. Male C57Bl6/J mice were fed a low-fat diet (LFD), high-fat diet (HFD), or methionine/folate/choline-deficient diet (MCD) to model a healthy liver, or mild and severe forms of NAFLD, respectively. After 8 weeks on diets, mice were orally administered PERC (300 mg/kg/day) or vehicle (5% aqueous Alkamuls-EL620) for 5 days. PERC-induced liver effects were exacerbated in both NAFLD groups. PERC exposure was associated with up-regulation of genes involved in xenobiotic, lipid, and glutathione metabolism, and down-regulation of the complement and coagulation cascades, regardless of the diet. Interestingly, HFD-fed mice, not MCD-fed mice, were generally more sensitive to PERC-induced liver effects. This was indicated by histopathology and transcriptional responses, where induction of genes associated with cell cycle and inflammation were prominent. Liver effects positively correlated with diet-specific differences in liver concentrations of PERC. We conclude that NAFLD alters the toxicodynamics of PERC and that NAFLD is a susceptibility factor that should be considered in future risk management decisions for PERC and other chlorinated solvents.
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Affiliation(s)
- Joseph A. Cichocki
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
| | - Shinji Furuya
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
| | - Yu-Syuan Luo
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
| | - Yasuhiro Iwata
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
| | - Kranti Konganti
- Texas A&M Institute for Genome Sciences and Society, Texas A&M University, College Station, Texas 77843
| | - Weihsueh A. Chiu
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
| | - David W. Threadgill
- Texas A&M Institute for Genome Sciences and Society, Texas A&M University, College Station, Texas 77843
- Department of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas 77843
| | - Igor P. Pogribny
- National Center for Toxicological Research, US FDA, Jefferson, Arkansas 72079
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
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Luo YS, Cichocki JA, McDonald TJ, Rusyn I. Simultaneous detection of the tetrachloroethylene metabolites S-(1,2,2-trichlorovinyl) glutathione, S-(1,2,2-trichlorovinyl)-L-cysteine, and N-acetyl-S-(1,2,2-trichlorovinyl)-L-cysteine in multiple mouse tissues via ultra-high performance liquid chromatography electrospray ionization tandem mass spectrometry. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2017; 80:513-524. [PMID: 28696834 PMCID: PMC5749336 DOI: 10.1080/15287394.2017.1330585] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Tetrachloroethylene (perchloroethylene; PERC) is a high-production volume chemical and ubiquitous environmental contaminant that is hazardous to human health. Toxicity attributed to PERC is mediated through oxidative and glutathione (GSH) conjugation metabolites. The conjugation of PERC by glutathione-s-transferase to generate S-(1,2,2-trichlorovinyl) glutathione (TCVG), which is subsequently metabolized to form S-(1,2,2-trichlorovinyl)-L-cysteine (TCVC) is of special importance to human health. Specifically, TCVC may be metabolized to N-acetyl-S-(1,2,2-trichlorovinyl)-L-cysteine (NAcTCVC) which is excreted through urine, or to electrophilic metabolites that are nephrotoxic and mutagenic. Little is known regarding toxicokinetics of TCVG, TCVC, and NAcTCVC as analytical methods for simultaneous determination of these metabolites in tissues have not yet been reported. Hence, an ultra-high-performance liquid chromatography electrospray ionization tandem mass spectrometry-based method was developed for analysis of TCVG, TCVC, and NAcTCVC in liver, kidneys, serum, and urine. The method is rapid, sensitive, robust, and selective for detection all three analytes in every tissue examined, with limits of detection (LOD) ranging from 1.8 to 68.2 femtomoles on column, depending on the analyte and tissue matrix. This method was applied to quantify levels of TCVG, TCVC, and NAcTCVC in tissues from mice treated with PERC (10 to 1000 mg/kg, orally) with limits of quantitation (LOQ) of 1-2.5 pmol/g in liver, 1-10 pmol/g in kidney, 1-2.5 pmol/ml in serum, and 2.5-5 pmol/ml in urine. This method is useful for further characterization of the GSH conjugative pathway of PERC in vivo and improved understanding of PERC toxicity.
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Affiliation(s)
- Yu-Syuan Luo
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Joseph A. Cichocki
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Thomas J. McDonald
- Department of Environmental and Occupational Health, Texas A&M University, College Station, TX, USA
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
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Cichocki JA, Furuya S, Venkatratnam A, McDonald TJ, Knap AH, Wade T, Sweet S, Chiu WA, Threadgill DW, Rusyn I. Characterization of Variability in Toxicokinetics and Toxicodynamics of Tetrachloroethylene Using the Collaborative Cross Mouse Population. ENVIRONMENTAL HEALTH PERSPECTIVES 2017; 125:057006. [PMID: 28572074 PMCID: PMC5726344 DOI: 10.1289/ehp788] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 09/26/2016] [Accepted: 10/25/2016] [Indexed: 05/27/2023]
Abstract
BACKGROUND Evaluation of interindividual variability is a challenging step in risk assessment. For most environmental pollutants, including perchloroethylene (PERC), experimental data are lacking, resulting in default assumptions being used to account for variability in toxicokinetics and toxicodynamics. OBJECTIVE We quantitatively examined the relationship between PERC toxicokinetics and toxicodynamics at the population level to test whether individuals with increased oxidative metabolism are be more sensitive to hepatotoxicity following PERC exposure. METHODS Male mice from 45 strains of the Collaborative Cross (CC) were orally administered a single dose of PERC (1,000 mg/kg) or vehicle (Alkamuls-EL620) and euthanized at various time points (n = 1/strain/time). Concentration–time profiles were generated for PERC and its primary oxidative metabolite trichloroacetate (TCA) in multiple tissues. Toxicodynamic phenotyping was also performed. RESULTS Significant variability among strains was observed in toxicokinetics of PERC and TCA in every tissue examined. Based on area under the curve (AUC), the range of liver TCA levels spanned nearly an order of magnitude (~8-fold). Expression of liver cytochrome P4502E1 did not correlate with TCA levels. Toxicodynamic phenotyping revealed an effect of PERC on bodyweight loss, induction of peroxisome proliferator activated receptor-alpha (PPARα)-regulated genes, and dysregulation of hepatic lipid homeostasis. Clustering was observed among a) liver levels of PERC, TCA, and triglycerides; b) TCA levels in liver and kidney; and c) TCA levels in serum, brain, fat, and lung. CONCLUSIONS Using the CC mouse population model, we have demonstrated a complex and highly variable relationship between PERC and TCA toxicokinetics and toxicodynamics at the population level. https://doi.org/10.1289/EHP788.
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Affiliation(s)
| | | | | | | | | | - Terry Wade
- Geochemical and Environmental Research Group
| | | | | | - David W Threadgill
- Department of Molecular and Cellular Medicine, Texas A&M University , College Station, Texas, USA
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences
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Cichocki JA, Furuya S, Konganti K, Luo YS, McDonald TJ, Iwata Y, Chiu WA, Threadgill DW, Pogribny IP, Rusyn I. Impact of Nonalcoholic Fatty Liver Disease on Toxicokinetics of Tetrachloroethylene in Mice. J Pharmacol Exp Ther 2017; 361:17-28. [PMID: 28148637 DOI: 10.1124/jpet.116.238790] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 01/30/2017] [Indexed: 12/19/2022] Open
Abstract
Lifestyle factors and chronic pathologic states are important contributors to interindividual variability in susceptibility to xenobiotic-induced toxicity. Nonalcoholic fatty liver disease (NAFLD) is an increasingly prevalent condition that can dramatically affect chemical metabolism. We examined the effect of NAFLD on toxicokinetics of tetrachloroethylene (PERC), a ubiquitous environmental contaminant that requires metabolic activation to induce adverse health effects. Mice (C57Bl/6J, male) were fed a low-fat diet (LFD), high-fat diet (HFD), or methionine/folate/choline-deficient diet (MCD) to model a healthy liver, steatosis, or nonalcoholic steatohepatitis (NASH), respectively. After 8 weeks, mice were orally administered a single dose of PERC (300 mg/kg) or vehicle (aqueous Alkamuls-EL620) and euthanized at various time points (1-36 hours). Levels of PERC and its metabolites were measured in blood/serum, liver, and fat. Effects of diets on liver gene expression and tissue:air partition coefficients were evaluated. We found that hepatic levels of PERC were 6- and 7.6-fold higher in HFD- and MCD-fed mice compared with LFD-fed mice; this was associated with an increased PERC liver:blood partition coefficient. Liver and serum Cmax for trichloroacetate (TCA) was lower in MCD-fed mice; however, hepatic clearance of TCA was profoundly reduced by HFD or MCD feeding, leading to TCA accumulation. Hepatic mRNA/protein expression and ex vivo activity assays revealed decreased xenobiotic metabolism in HFD- and MCD-, compared with LFD-fed, groups. In conclusion, experimental NAFLD was associated with modulation of xenobiotic disposition and metabolism and increased hepatic exposure to PERC and TCA. Underlying NAFLD may be an important susceptibility factor for PERC-associated hepatotoxicity.
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Affiliation(s)
- Joseph A Cichocki
- Department of Veterinary Integrative Biosciences (J.A.C; S.F; Y.S.L; Y.I; W.C; I.R), Texas A&M Institute for Genome Sciences and Society (K.K; D.W.T; I.R), Department of Environmental and Occupational Health (T.J.M), and Department of Molecular and Cellular Medicine (D.W.T), Texas A&M University, College Station, Texas; and National Center for Toxicological Research, US FDA, Jefferson, Arkansas (I.P)
| | - Shinji Furuya
- Department of Veterinary Integrative Biosciences (J.A.C; S.F; Y.S.L; Y.I; W.C; I.R), Texas A&M Institute for Genome Sciences and Society (K.K; D.W.T; I.R), Department of Environmental and Occupational Health (T.J.M), and Department of Molecular and Cellular Medicine (D.W.T), Texas A&M University, College Station, Texas; and National Center for Toxicological Research, US FDA, Jefferson, Arkansas (I.P)
| | - Kranti Konganti
- Department of Veterinary Integrative Biosciences (J.A.C; S.F; Y.S.L; Y.I; W.C; I.R), Texas A&M Institute for Genome Sciences and Society (K.K; D.W.T; I.R), Department of Environmental and Occupational Health (T.J.M), and Department of Molecular and Cellular Medicine (D.W.T), Texas A&M University, College Station, Texas; and National Center for Toxicological Research, US FDA, Jefferson, Arkansas (I.P)
| | - Yu-Syuan Luo
- Department of Veterinary Integrative Biosciences (J.A.C; S.F; Y.S.L; Y.I; W.C; I.R), Texas A&M Institute for Genome Sciences and Society (K.K; D.W.T; I.R), Department of Environmental and Occupational Health (T.J.M), and Department of Molecular and Cellular Medicine (D.W.T), Texas A&M University, College Station, Texas; and National Center for Toxicological Research, US FDA, Jefferson, Arkansas (I.P)
| | - Thomas J McDonald
- Department of Veterinary Integrative Biosciences (J.A.C; S.F; Y.S.L; Y.I; W.C; I.R), Texas A&M Institute for Genome Sciences and Society (K.K; D.W.T; I.R), Department of Environmental and Occupational Health (T.J.M), and Department of Molecular and Cellular Medicine (D.W.T), Texas A&M University, College Station, Texas; and National Center for Toxicological Research, US FDA, Jefferson, Arkansas (I.P)
| | - Yasuhiro Iwata
- Department of Veterinary Integrative Biosciences (J.A.C; S.F; Y.S.L; Y.I; W.C; I.R), Texas A&M Institute for Genome Sciences and Society (K.K; D.W.T; I.R), Department of Environmental and Occupational Health (T.J.M), and Department of Molecular and Cellular Medicine (D.W.T), Texas A&M University, College Station, Texas; and National Center for Toxicological Research, US FDA, Jefferson, Arkansas (I.P)
| | - Weihsueh A Chiu
- Department of Veterinary Integrative Biosciences (J.A.C; S.F; Y.S.L; Y.I; W.C; I.R), Texas A&M Institute for Genome Sciences and Society (K.K; D.W.T; I.R), Department of Environmental and Occupational Health (T.J.M), and Department of Molecular and Cellular Medicine (D.W.T), Texas A&M University, College Station, Texas; and National Center for Toxicological Research, US FDA, Jefferson, Arkansas (I.P)
| | - David W Threadgill
- Department of Veterinary Integrative Biosciences (J.A.C; S.F; Y.S.L; Y.I; W.C; I.R), Texas A&M Institute for Genome Sciences and Society (K.K; D.W.T; I.R), Department of Environmental and Occupational Health (T.J.M), and Department of Molecular and Cellular Medicine (D.W.T), Texas A&M University, College Station, Texas; and National Center for Toxicological Research, US FDA, Jefferson, Arkansas (I.P)
| | - Igor P Pogribny
- Department of Veterinary Integrative Biosciences (J.A.C; S.F; Y.S.L; Y.I; W.C; I.R), Texas A&M Institute for Genome Sciences and Society (K.K; D.W.T; I.R), Department of Environmental and Occupational Health (T.J.M), and Department of Molecular and Cellular Medicine (D.W.T), Texas A&M University, College Station, Texas; and National Center for Toxicological Research, US FDA, Jefferson, Arkansas (I.P)
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences (J.A.C; S.F; Y.S.L; Y.I; W.C; I.R), Texas A&M Institute for Genome Sciences and Society (K.K; D.W.T; I.R), Department of Environmental and Occupational Health (T.J.M), and Department of Molecular and Cellular Medicine (D.W.T), Texas A&M University, College Station, Texas; and National Center for Toxicological Research, US FDA, Jefferson, Arkansas (I.P)
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Cichocki JA, Guyton KZ, Guha N, Chiu WA, Rusyn I, Lash LH. Target Organ Metabolism, Toxicity, and Mechanisms of Trichloroethylene and Perchloroethylene: Key Similarities, Differences, and Data Gaps. J Pharmacol Exp Ther 2016; 359:110-23. [PMID: 27511820 PMCID: PMC5034707 DOI: 10.1124/jpet.116.232629] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 08/09/2016] [Indexed: 01/18/2023] Open
Abstract
Trichloroethylene (TCE) and perchloroethylene or tetrachloroethylene (PCE) are high-production volume chemicals with numerous industrial applications. As a consequence of their widespread use, these chemicals are ubiquitous environmental contaminants to which the general population is commonly exposed. It is widely assumed that TCE and PCE are toxicologically similar; both are simple olefins with three (TCE) or four (PCE) chlorines. Nonetheless, despite decades of research on the adverse health effects of TCE or PCE, few studies have directly compared these two toxicants. Although the metabolic pathways are qualitatively similar, quantitative differences in the flux and yield of metabolites exist. Recent human health assessments have uncovered some overlap in target organs that are affected by exposure to TCE or PCE, and divergent species- and sex-specificity with regard to cancer and noncancer hazards. The objective of this minireview is to highlight key similarities, differences, and data gaps in target organ metabolism and mechanism of toxicity. The main anticipated outcome of this review is to encourage research to 1) directly compare the responses to TCE and PCE using more sensitive biochemical techniques and robust statistical comparisons; 2) more closely examine interindividual variability in the relationship between toxicokinetics and toxicodynamics for TCE and PCE; 3) elucidate the effect of coexposure to these two toxicants; and 4) explore new mechanisms for target organ toxicity associated with TCE and/or PCE exposure.
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Affiliation(s)
- Joseph A Cichocki
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas (J.A.C., W.A.C., I.R.); International Agency for Research on Cancer, Lyon, France (K.Z.G., N.G.); Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan (L.H.L.)
| | - Kathryn Z Guyton
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas (J.A.C., W.A.C., I.R.); International Agency for Research on Cancer, Lyon, France (K.Z.G., N.G.); Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan (L.H.L.)
| | - Neela Guha
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas (J.A.C., W.A.C., I.R.); International Agency for Research on Cancer, Lyon, France (K.Z.G., N.G.); Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan (L.H.L.)
| | - Weihsueh A Chiu
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas (J.A.C., W.A.C., I.R.); International Agency for Research on Cancer, Lyon, France (K.Z.G., N.G.); Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan (L.H.L.)
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas (J.A.C., W.A.C., I.R.); International Agency for Research on Cancer, Lyon, France (K.Z.G., N.G.); Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan (L.H.L.)
| | - Lawrence H Lash
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas (J.A.C., W.A.C., I.R.); International Agency for Research on Cancer, Lyon, France (K.Z.G., N.G.); Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan (L.H.L.)
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15
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Guyton KZ, Hogan KA, Scott CS, Cooper GS, Bale AS, Kopylev L, Barone S, Makris SL, Glenn B, Subramaniam RP, Gwinn MR, Dzubow RC, Chiu WA. Human health effects of tetrachloroethylene: key findings and scientific issues. ENVIRONMENTAL HEALTH PERSPECTIVES 2014; 122:325-34. [PMID: 24531164 PMCID: PMC3984230 DOI: 10.1289/ehp.1307359] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 02/11/2014] [Indexed: 05/07/2023]
Abstract
BACKGROUND The U.S. Environmental Protection Agency (EPA) completed a toxicological review of tetrachloroethylene (perchloroethylene, PCE) in February 2012 in support of the Integrated Risk Information System (IRIS). OBJECTIVES We reviewed key findings and scientific issues regarding the human health effects of PCE described in the U.S. EPA's Toxicological Review of Tetrachloroethylene (Perchloroethylene). METHODS The updated assessment of PCE synthesized and characterized a substantial database of epidemiological, experimental animal, and mechanistic studies. Key scientific issues were addressed through modeling of PCE toxicokinetics, synthesis of evidence from neurological studies, and analyses of toxicokinetic, mechanistic, and other factors (tumor latency, severity, and background rate) in interpreting experimental animal cancer findings. Considerations in evaluating epidemiological studies included the quality (e.g., specificity) of the exposure assessment methods and other essential design features, and the potential for alternative explanations for observed associations (e.g., bias or confounding). DISCUSSION Toxicokinetic modeling aided in characterizing the complex metabolism and multiple metabolites that contribute to PCE toxicity. The exposure assessment approach-a key evaluation factor for epidemiological studies of bladder cancer, non-Hodgkin lymphoma, and multiple myeloma-provided suggestive evidence of carcinogenicity. Bioassay data provided conclusive evidence of carcinogenicity in experimental animals. Neurotoxicity was identified as a sensitive noncancer health effect, occurring at low exposures: a conclusion supported by multiple studies. Evidence was integrated from human, experimental animal, and mechanistic data sets in assessing adverse health effects of PCE. CONCLUSIONS PCE is likely to be carcinogenic to humans. Neurotoxicity is a sensitive adverse health effect of PCE.
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16
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Arciello M, Gori M, Maggio R, Barbaro B, Tarocchi M, Galli A, Balsano C. Environmental pollution: a tangible risk for NAFLD pathogenesis. Int J Mol Sci 2013; 14:22052-66. [PMID: 24213605 PMCID: PMC3856051 DOI: 10.3390/ijms141122052] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 10/18/2013] [Accepted: 10/24/2013] [Indexed: 12/13/2022] Open
Abstract
The liver is crucial for human life, and the health of this organ often mirrors the health of the individual. The liver can be the target of several diseases, the most prevalent of which, as a consequence of development and changes in human lifestyles, is the nonalcoholic fatty liver disease (NAFLD). NAFLD is a multifactorial disease that embraces many histo-pathologic conditions and is highly linked to metabolic derangements. Technological progress and industrialization have also had the consequence of releasing pollutants in the environment, for instance pesticides or solvents, as well as by-products of discharge, such as the particulate matter. In the last decade, a growing body of evidence has emerged, shedding light on the potential impact of environmental pollutants on liver health and, in particular, on NAFLD occurrence. These contaminants have a great steatogenic potential and need to be considered as tangible NAFLD risk factors. There is an urgent need for a deeper comprehension of their molecular mechanisms of action, as well as for new lines of intervention to reduce their worldwide diffusion. This review wishes to sensitize the community to the effects of several environmental pollutants on liver health.
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Affiliation(s)
- Mario Arciello
- Francesco Balsano Foundation, via G.B. Martini 6, Rome 00198, Italy; E-Mails: (M.A.); (M.G.); (R.M.); (B.B.)
| | - Manuele Gori
- Francesco Balsano Foundation, via G.B. Martini 6, Rome 00198, Italy; E-Mails: (M.A.); (M.G.); (R.M.); (B.B.)
- Department of Clinical and Molecular Sciences, Polytechnic University of Marche, Via Tronto 10, Ancona 60020, Italy
| | - Roberta Maggio
- Francesco Balsano Foundation, via G.B. Martini 6, Rome 00198, Italy; E-Mails: (M.A.); (M.G.); (R.M.); (B.B.)
| | - Barbara Barbaro
- Francesco Balsano Foundation, via G.B. Martini 6, Rome 00198, Italy; E-Mails: (M.A.); (M.G.); (R.M.); (B.B.)
| | - Mirko Tarocchi
- Gastroenterology Unit, Department of Experimental and Clinical Biochemical Sciences, University of Florence, Viale Pieraccini 6, Florence 50139, Italy; E-Mails: (M.T.); (A.G.)
| | - Andrea Galli
- Gastroenterology Unit, Department of Experimental and Clinical Biochemical Sciences, University of Florence, Viale Pieraccini 6, Florence 50139, Italy; E-Mails: (M.T.); (A.G.)
| | - Clara Balsano
- Francesco Balsano Foundation, via G.B. Martini 6, Rome 00198, Italy; E-Mails: (M.A.); (M.G.); (R.M.); (B.B.)
- Institute of Molecular Biology and Pathology (IBPM)-National Research Council (CNR), Piazzale Aldo Moro 7, Rome 00185, Italy
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +39-06-4993-3094; Fax: +39-06-4991-0908
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Wahlang B, Beier JI, Clair HB, Bellis-Jones HJ, Falkner KC, McClain CJ, Cave MC. Toxicant-associated steatohepatitis. Toxicol Pathol 2013; 41:343-60. [PMID: 23262638 PMCID: PMC5114851 DOI: 10.1177/0192623312468517] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Hepatotoxicity is the most common organ injury due to occupational and environmental exposures to industrial chemicals. A wide range of liver pathologies ranging from necrosis to cancer have been observed following chemical exposures both in humans and in animal models. Toxicant-associated fatty liver disease (TAFLD) is a recently named form of liver injury pathologically similar to alcoholic liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD). Toxicant-associated steatohepatitis (TASH) is a more severe form of TAFLD characterized by hepatic steatosis, inflammatory infiltrate, and in some cases, fibrosis. While subjects with TASH have exposures to industrial chemicals, such as vinyl chloride, they do not have traditional risk factors for fatty liver such as significant alcohol consumption or obesity. Conventional biomarkers of hepatotoxicity including serum alanine aminotransferase activity may be normal in TASH, making screening problematic. This article examines selected chemical exposures associated with TAFLD in human subjects or animal models and concisely reviews the closely related NAFLD and ALD.
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Affiliation(s)
- Banrida Wahlang
- Department of Pharmacology & Toxicology, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - Juliane I. Beier
- Department of Pharmacology & Toxicology, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - Heather B. Clair
- Department of Pharmacology & Toxicology, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - Heather J. Bellis-Jones
- Department of Pharmacology & Toxicology, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - K. Cameron Falkner
- Department of Medicine, Division of Gastroenterology, Hepatology, and Nutrition, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - Craig J. McClain
- Department of Pharmacology & Toxicology, University of Louisville School of Medicine, Louisville, Kentucky, USA
- Department of Medicine, Division of Gastroenterology, Hepatology, and Nutrition, University of Louisville School of Medicine, Louisville, Kentucky, USA
- Robley Rex Louisville VAMC, Louisville, Kentucky, USA
| | - Matt C. Cave
- Department of Pharmacology & Toxicology, University of Louisville School of Medicine, Louisville, Kentucky, USA
- Department of Medicine, Division of Gastroenterology, Hepatology, and Nutrition, University of Louisville School of Medicine, Louisville, Kentucky, USA
- Robley Rex Louisville VAMC, Louisville, Kentucky, USA
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Survey of hazardous organic compounds in the groundwater, air and wastewater effluents near the Tehran automobile industry. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2012; 90:155-9. [PMID: 23160750 DOI: 10.1007/s00128-012-0890-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2012] [Accepted: 11/09/2012] [Indexed: 12/07/2022]
Abstract
Potential of wastewater treatment in car industry and groundwater contamination by volatile organic compounds include perchloroethylene (PCE), trichloroethylene (TCE) and dichloromethane (DCM) near car industry was conducted in this study. Samples were collected in September through December 2011 from automobile industry. Head-space Gas chromatography with FID detector is used for analysis. Mean PCE levels in groundwater ranged from 0 to 63.56 μg L(-1) with maximum level of 89.1 μg L(-1). Mean TCE from 0 to 76.63 μg L(-1) with maximum level of 112 μg L(-1). Due to the data obtained from pre treatment of car staining site and conventional wastewater treatment in car factory, the most of TCE, PCE and DCM removed by pre aeration. Therefor this materials entry from liquid phase to air phase and by precipitation leak out to the groundwater. As a consequence these pollutants have a many negative health effect on the workers by air and groundwater.
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Rajamanikandan S, Sindhu T, Durgapriya D, Sophia D, Ragavendran P, Gopalakrishnan VK. Protective effect of Mollugo nudicaulis Lam. on acute liver injury induced by perchloroethylene in experimental rats. ASIAN PAC J TROP MED 2012; 5:862-7. [DOI: 10.1016/s1995-7645(12)60161-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 03/31/2012] [Accepted: 04/05/2012] [Indexed: 11/24/2022] Open
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Development and evaluation of a harmonized physiologically based pharmacokinetic (PBPK) model for perchloroethylene toxicokinetics in mice, rats, and humans. Toxicol Appl Pharmacol 2011; 253:203-34. [PMID: 21466818 DOI: 10.1016/j.taap.2011.03.020] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 03/09/2011] [Accepted: 03/27/2011] [Indexed: 02/06/2023]
Abstract
This article reports on the development of a "harmonized" PBPK model for the toxicokinetics of perchloroethylene (tetrachloroethylene or perc) in mice, rats, and humans that includes both oxidation and glutathione (GSH) conjugation of perc, the internal kinetics of the oxidative metabolite trichloroacetic acid (TCA), and the urinary excretion kinetics of the GSH conjugation metabolites N-Acetylated trichlorovinyl cysteine and dichloroacetic acid. The model utilizes a wider range of in vitro and in vivo data than any previous analysis alone, with in vitro data used for initial, or "baseline," parameter estimates, and in vivo datasets separated into those used for "calibration" and those used for "evaluation." Parameter calibration utilizes a limited Bayesian analysis involving flat priors and making inferences only using posterior modes obtained via Markov chain Monte Carlo (MCMC). As expected, the major route of elimination of absorbed perc is predicted to be exhalation as parent compound, with metabolism accounting for less than 20% of intake except in the case of mice exposed orally, in which metabolism is predicted to be slightly over 50% at lower exposures. In all three species, the concentration of perc in blood, the extent of perc oxidation, and the amount of TCA production is well-estimated, with residual uncertainties of ~2-fold. However, the resulting range of estimates for the amount of GSH conjugation is quite wide in humans (~3000-fold) and mice (~60-fold). While even high-end estimates of GSH conjugation in mice are lower than estimates of oxidation, in humans the estimated rates range from much lower to much higher than rates for perc oxidation. It is unclear to what extent this range reflects uncertainty, variability, or a combination. Importantly, by separating total perc metabolism into separate oxidative and conjugative pathways, an approach also recommended in a recent National Research Council review, this analysis reconciles the disparity between those previously published PBPK models that concluded low perc metabolism in humans and those that predicted high perc metabolism in humans. In essence, both conclusions are consistent with the data if augmented with some additional qualifications: in humans, oxidative metabolism is low, while GSH conjugation metabolism may be high or low, with uncertainty and/or interindividual variability spanning three orders of magnitude. More direct data on the internal kinetics of perc GSH conjugation, such as trichlorovinyl glutathione or tricholorvinyl cysteine in blood and/or tissues, would be needed to better characterize the uncertainty and variability in GSH conjugation in humans.
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