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Su AL, Lash LH, Loch-Caruso R. N-Acetyl-L-cysteine and aminooxyacetic acid differentially modulate toxicity of the trichloroethylene metabolite S-(1,2-dichlorovinyl)-L-cysteine in human placental villous trophoblast BeWo cells. Toxicology 2023; 495:153611. [PMID: 37544576 PMCID: PMC10874504 DOI: 10.1016/j.tox.2023.153611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Revised: 07/23/2023] [Accepted: 08/03/2023] [Indexed: 08/08/2023]
Abstract
Trichloroethylene (TCE) is a known human carcinogen with toxicity attributed to its metabolism. S-(1,2-Dichlorovinyl)-L-cysteine (DCVC) is a metabolite of TCE formed downstream in TCE glutathione (GSH) conjugation and is upstream of several toxic metabolites. Despite knowledge that DCVC stimulates reactive oxygen species (ROS) generation and apoptosis in placental cells, the extent to which these outcomes are attributable to DCVC metabolism is unknown. The current study used N-acetyl-L-cysteine (NAC) at 5 mM and aminooxyacetic acid (AOAA) at 1 mM as pharmacological modifiers of DCVC metabolism to investigate DCVC toxicity at concentrations of 5-50 µM in the human placental trophoblast BeWo cell model capable of forskolin-stimulated syncytialization. Exposures of unsyncytialized BeWo cells, BeWo cells undergoing syncytialization, and syncytialized BeWo cells were studied. NAC pre/co-treatment with DCVC either failed to inhibit or exacerbated DCVC-induced H2O2 abundance, PRDX2 mRNA expression, and BCL2 mRNA expression. Although NAC increased mRNA expression of CYP3A4, which would be consistent with increased generation of the toxic metabolite N-acetyl-DCVC sulfoxide (NAcDCVCS), a CYP3A4 inhibitor ketoconazole did not significantly alter BeWo cell responses. Moreover, AOAA failed to inhibit cysteine conjugate β-lyase (CCBL), which bioactivates DCVC, and did not affect the percentage of nuclei condensed or fragmented, a measure of apoptosis, in all BeWo cell models. However, syncytialized cells had higher CCBL activity compared to unsyncytialized cells, suggesting that the former may be more sensitive to DCVC toxicity. Together, although neither NAC nor AOAA mitigated DCVC toxicity, differences in CCBL activity and potentially CYP3A4 expression dictated the differential toxicity derived from DCVC.
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Affiliation(s)
- Anthony L Su
- Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109-2029, USA.
| | - Lawrence H Lash
- Department of Pharmacology, Wayne State University School of Medicine, 540 East Canfield Avenue, Detroit, MI 48201, USA
| | - Rita Loch-Caruso
- Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109-2029, USA
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Su AL, Harris SM, Elkin ER, Karnovsky A, Colacino J, Loch-Caruso RK. Trichloroethylene Metabolite S-(1,2-Dichlorovinyl)-l-cysteine Stimulates Changes in Energy Metabolites and Amino Acids in the BeWo Human Placental Trophoblast Model during Syncytialization. Chem Res Toxicol 2023; 36:882-899. [PMID: 37162359 PMCID: PMC10499396 DOI: 10.1021/acs.chemrestox.3c00007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Syncytialization, the fusion of cytotrophoblasts into an epithelial barrier that constitutes the maternal-fetal interface, is a crucial event of placentation. This process is characterized by distinct changes to amino acid and energy metabolism. A metabolite of the industrial solvent trichloroethylene (TCE), S-(1,2-dichlorovinyl)-l-cysteine (DCVC), modifies energy metabolism and amino acid abundance in HTR-8/SVneo extravillous trophoblasts. In the current study, we investigated DCVC-induced changes to energy metabolism and amino acids during forskolin-stimulated syncytialization in BeWo cells, a human villous trophoblastic cell line that models syncytialization in vitro. BeWo cells were exposed to forskolin at 100 μM for 48 h to stimulate syncytialization. During syncytialization, BeWo cells were also treated with DCVC at 0 (control), 10, or 20 μM. Following treatment, the targeted metabolomics platform, "Tricarboxylic Acid Plus", was used to identify changes in energy metabolism and amino acids. DCVC treatment during syncytialization decreased oleic acid, aspartate, proline, uridine diphosphate (UDP), UDP-d-glucose, uridine monophosphate, and cytidine monophosphate relative to forskolin-only treatment controls, but did not increase any measured metabolite. Notable changes stimulated by syncytialization in the absence of DCVC included increased adenosine monophosphate and guanosine monophosphate, as well as decreased aspartate and glutamate. Pathway analysis revealed multiple pathways in amino acid and sugar metabolisms that were altered with forskolin-stimulated syncytialization alone and DCVC treatment during syncytialization. Analysis of ratios of metabolites within the pathways revealed that DCVC exposure during syncytialization changed metabolite ratios in the same or different direction compared to syncytialization alone. Building off our oleic acid findings, we found that extracellular matrix metalloproteinase-2, which is downstream in oleic acid signaling, underwent the same changes as oleic acid. Together, the metabolic changes stimulated by DCVC treatment during syncytialization suggest changes in energy metabolism and amino acid abundance as potential mechanisms by which DCVC could impact syncytialization and pregnancy.
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Affiliation(s)
- Anthony L. Su
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109
| | - Sean M. Harris
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109
| | - Elana R. Elkin
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109
| | - Alla Karnovsky
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Justin Colacino
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109
- Department of Nutritional Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Rita Karen Loch-Caruso
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109
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Elkin ER, Su AL, Dou JF, Colacino JA, Bridges D, Padmanabhan V, Harris SM, Boldenow E, Loch-Caruso R, Bakulski KM. Sexually concordant and dimorphic transcriptional responses to maternal trichloroethylene and/or N-acetyl cysteine exposure in Wistar rat placental tissue. Toxicology 2023; 483:153371. [PMID: 36396003 PMCID: PMC10078828 DOI: 10.1016/j.tox.2022.153371] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 10/20/2022] [Accepted: 11/02/2022] [Indexed: 11/16/2022]
Abstract
Numerous Superfund sites are contaminated with the volatile organic chemical trichloroethylene (TCE). In women, exposure to TCE in pregnancy is associated with reduced birth weight. Our previous study reported that TCE exposure in pregnant rats decreased fetal weight and elevated oxidative stress biomarkers in placentae, suggesting placental injury as a potential mechanism of TCE-induced adverse birth outcomes. In this study, we investigated if co-exposure with the antioxidant N-acetylcysteine (NAC) attenuates TCE exposure effects on RNA expression. Timed-pregnant Wistar rats were exposed orally to 480 mg TCE/kg/day on gestation days 6-16. Exposure of 200 mg NAC/kg/day alone or as a pre/co-exposure with TCE occurred on gestation days 5-16 to stimulate antioxidant genes prior to TCE exposure. Tissue was collected on gestation day 16. In male and female placentae, we evaluated TCE- and/or NAC-induced changes to gene expression and pathway enrichment analyses using false discovery rate (FDR) and fold-change criteria. In female placentae, exposure to TCE caused significant differential expression 129 genes while the TCE+NAC altered 125 genes, compared with controls (FDR< 0.05 + fold-change >1). In contrast, in male placentae TCE exposure differentially expressed 9 genes and TCE+NAC differentially expressed 35 genes, compared with controls (FDR< 0.05 + fold-change >1). NAC alone did not significantly alter gene expression in either sex. Differentially expressed genes observed with TCE exposure were enriched in mitochondrial biogenesis and oxidative phosphorylation pathways in females whereas immune system pathways and endoplasmic reticulum stress pathways were differentially expressed in both sexes (FDR<0.05). TCE treatment was differentially enriched for genes regulated by the transcription factors ATF6 (both sexes) and ATF4 (males only), indicating a cellular condition triggered by misfolded proteins during endoplasmic reticulum stress. This study demonstrates novel genes and pathways involved in TCE-induced placental injury and showed antioxidant co-treatment largely did not attenuate TCE exposure effects.
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Affiliation(s)
- Elana R Elkin
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, MI, USA.
| | - Anthony L Su
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, MI, USA
| | - John F Dou
- Department of Epidemiology, University of Michigan, Ann Arbor, MI, USA
| | - Justin A Colacino
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, MI, USA; Department of Nutritional Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Dave Bridges
- Department of Nutritional Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Vasantha Padmanabhan
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, MI, USA; Department of Nutritional Sciences, University of Michigan, Ann Arbor, MI, USA; Department of Pediatrics, Michigan Medicine, Ann Arbor, MI, USA; Department of Obstetrics and Gynecology, Michigan Medicine, Ann Arbor, MI, USA
| | - Sean M Harris
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Erica Boldenow
- Department of Biology, Calvin University, Grand Rapids, MI, USA
| | - Rita Loch-Caruso
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Kelly M Bakulski
- Department of Epidemiology, University of Michigan, Ann Arbor, MI, USA
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Elkin ER, Su AL, Kilburn BA, Bakulski KM, Armant DR, Loch-Caruso R. Toxicity assessments of selected trichloroethylene and perchloroethylene metabolites in three in vitro human placental models. Reprod Toxicol 2022; 109:109-120. [PMID: 35304307 PMCID: PMC9107309 DOI: 10.1016/j.reprotox.2022.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 03/07/2022] [Accepted: 03/10/2022] [Indexed: 01/25/2023]
Abstract
Residential and occupational exposures to the industrial solvents perchloroethylene (PERC) and trichloroethylene (TCE) present public health concerns. In humans, maternal PERC and TCE exposures can be associated with adverse birth outcomes. Because PERC and TCE are biotransformed to toxic metabolites and placental dysfunction can contribute to adverse birth outcomes, the present study compared the toxicity of key PERC and TCE metabolites in three in vitro human placenta models. We measured cell viability and caspase 3 + 7 activity in the HTR-8/SVneo and BeWo cell lines, and caspase 3 + 7 activity in first trimester villous explant cultures. Cultures were exposed for 24 h to 5-100 µM S-(1,2-dichlorovinyl)-L-cysteine (DCVC) and S-(1,2,2-trichlorovinyl)-L-cysteine (TCVC), or 5-200 µM trichloroacetate (TCA) and dichloroacetate (DCA). DCVC significantly reduced cell viability and increased caspase 3 + 7 activity in HTR-8/SVneo cells at a lower concentration (20 µM) compared with concentrations toxic to BeWo cells and villous explants. Similarly, TCVC reduced cell viability and increased caspase 3 + 7 activity in HTR-8/SVneo cells but not in BeWo cells. TCA and DCA had only negligible effects on HTR-8/SVneo or BeWo cells. This study advances understanding of potential risks of PERC and TCE exposure during pregnancy by identifying metabolites toxic in placental cells and tissues.
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Affiliation(s)
- Elana R Elkin
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan, USA; Department of Nutritional Sciences, University of Michigan, Ann Arbor, Michigan, USA.
| | - Anthony L Su
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan, USA; Department of Nutritional Sciences, University of Michigan, Ann Arbor, Michigan, USA
| | - Brian A Kilburn
- Department of Nutritional Sciences, University of Michigan, Ann Arbor, Michigan, USA; Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Kelly M Bakulski
- Department of Epidemiology, University of Michigan, Ann Arbor, Michigan, USA; Department of Nutritional Sciences, University of Michigan, Ann Arbor, Michigan, USA
| | - D Randall Armant
- Department of Nutritional Sciences, University of Michigan, Ann Arbor, Michigan, USA; Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan, USA; Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Rita Loch-Caruso
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan, USA
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Su AL, Harris SM, Elkin ER, Karnovsky A, Colacino JA, Loch-Caruso R. Trichloroethylene modifies energy metabolites in the amniotic fluid of Wistar rats. Reprod Toxicol 2022; 109:80-92. [PMID: 35301063 PMCID: PMC9000924 DOI: 10.1016/j.reprotox.2022.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 03/05/2022] [Accepted: 03/11/2022] [Indexed: 10/18/2022]
Abstract
Exposure to trichloroethylene (TCE), an industrial solvent, is associated with several adverse pregnancy outcomes in humans and decreased fetal weight in rats. However, effects of TCE on energy metabolites in amniotic fluid, which have associations with pregnancy outcomes, has not been published previously. In the current exploratory study, timed-pregnant Wistar rats were exposed to 480 mg TCE/kg/day via vanilla wafer or to vehicle (wafer) alone from gestational day (GD) 6-16. Amniotic fluid collected on GD 16 was analyzed for metabolites important in energy metabolism using short chain fatty acid and tricarboxylic acid plus platforms (N = 4 samples/sex/treatment). TCE decreased concentrations of the following metabolites in amniotic fluid for both fetal sexes: 6-phosphogluconate, guanosine diphosphate, adenosine diphosphate, adenosine triphosphate, and flavin adenine dinucleotide. TCE decreased fructose 1,6-bisphosphate and guanosine triphosphate concentrations in amniotic fluid of male but not female fetuses. Moreover, TCE decreased uridine diphosphate-D-glucuronate concentrations, and increased arginine and phosphocreatine concentrations, in amniotic fluid of female fetuses only. No metabolites were increased in amniotic fluid of male fetuses. Pathway analysis suggested that TCE altered folate biosynthesis and pentose phosphate pathway in both sexes. Using metabolite ratios to investigate changes within specific pathways, some ratio alterations, including those in arginine metabolism and phenylalanine metabolism, were detected in females only. Ratio analysis also suggested enzymes, including gluconokinase, as potential TCE targets. Together, results from this exploratory study suggest that TCE differentially modified energy metabolites in amniotic fluid based on sex. These findings may inform future studies of TCE reproductive toxicity.
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Affiliation(s)
- Anthony L Su
- Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109, USA.
| | - Sean M Harris
- Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109, USA.
| | - Elana R Elkin
- Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109, USA.
| | - Alla Karnovsky
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Palmer Commons, 100 Washtenaw Ave #2017, Ann Arbor, MI 48109, USA.
| | - Justin A Colacino
- Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109, USA; Department of Nutritional Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109, USA.
| | - Rita Loch-Caruso
- Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109, USA.
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Cx43 overexpression is involved in the hyper-proliferation effect of trichloroethylene on human embryonic stem cells. Toxicology 2022; 465:153065. [PMID: 34896440 DOI: 10.1016/j.tox.2021.153065] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 10/19/2022]
Abstract
Trichloroethylene (TCE) is a major environmental contaminant. Maternal exposure of TCE is linked to developmental defects, but the mechanisms remain to be elucidated. Along with a strategy of 3Rs principle, human embryonic stem cells (hESCs) are regarded as most promising in vitro models for developmental toxicity studies. TCE interfered with hESCs differentiation, but no report was available for TCE effects on hESCs proliferation. Here, we aimed to explore the toxic effects and mechanisms of TCE on hESCs proliferation. Treatment with TCE, did not affect the pluripotency genes expression. However, TCE enhanced hESCs proliferation, manifested by increased cell number, PCNA expression and EdU incorporation. Moreover, TCE exposure upregulated the protein expression levels of Cx43 and cyclin-dependent kinases. Knockdown of Cx43 attenuated the TCE-induced cell hyper-proliferation and CDK2 upregulation. Furthermore, TCE increased Akt phosphorylation, and the inhibition of Akt blocked the TCE-induced Cx43 overexpression and cell proliferation. In conclusion, TCE exposure resulted in upregulation of Cx43 via Akt phosphorylation, consequently stimulated CDK2 expression, contributing to hyper-proliferation in hESCs. Our study brings to light that TCE stimulated the proliferation of hESCs via Cx43, providing a new research avenue for the causes of TCE-induced developmental toxicity.
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