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Xia Y, Luo D, Xu A, Zhao B, Lin H, Yao H, Li S. Insight into the mechanism of melatonin in attenuating PCB126-induced liver injury: Resistance to ROS-dependent NETs formation to alleviate inflammation and lipid metabolism dysfunction. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 270:115923. [PMID: 38171107 DOI: 10.1016/j.ecoenv.2023.115923] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 12/18/2023] [Accepted: 12/29/2023] [Indexed: 01/05/2024]
Abstract
3,3',4',4',5-Polychlorinated biphenyls (PCB126) is classified as a persistent organic environmental pollutant that can cause liver damage by producing excessive reactive oxygen species (ROS). ROS also can stimulate neutrophil extracellular traps (NETs) formation, which cause damage to organism if NETs are produced in excess. Melatonin is generally considered to possess strong antioxidant and anti-inflammation prosperities, but it is unclear whether it can alleviate PCB126-induced injury. To explore whether PCB126-induced liver injury is related to the formation of NETs and whether melatonin has a potent protective effect, we established PCB126 exposure/ PCB126 and melatonin co-treatment mouse models by gavage. To further clarify the specific mechanism, we also cultured neutrophils and AML12 cells to replicate in vivo model. Here, we found PCB126 exposure resulted in an elevation in the activities of MDA, LPO, PCO, and 8-OHdG, and a reduction in the activities of CAT, GSH-PX and SOD. We found that PCB126 exposure led to an elevation in the expression levels of chemokines (CCL2, CCL3, CCL4, CXCL12, and CXCL8) and marker factors for NETs formation (MPO, NE, NOX2, PKCα, and PKCζ) in the PCB126 group. IF, SYTOX staining, and SEM results also revealed that PCB126 could stimulate NETs formation. In addition, results of a co-culture system of PBNs and AML12 cells revealed that the expression levels of inflammatory cytokines (IL-1β, IL-6, and TNF-α) significantly decreased and the expression levels of metabolism factors (Fas, Acc, and Srebp) slightly decreased for scavenging NETs, indicating NETs formation aggravated PCB126-induced hepatic damages. Noteworthy, treatment with melatonin reversed these results. In summary, our findings revealed that melatonin alleviated hepatic damage aggravated by PCB126-induced ROS-dependent NETs formation through suppressing excessive ROS production. This finding not only enriches toxicological mechanism of PCB126, but more importantly extends biological effects of melatonin and its potential application values.
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Affiliation(s)
- Yu Xia
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Dongliu Luo
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Anqi Xu
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Bing Zhao
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Hongjin Lin
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Haidong Yao
- Department of Biosciences and Nutrition, Karolinska Institutet, Sweden
| | - Shu Li
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China.
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Ronis MJ, Watt J, Pulliam CF, Williams AE, Alund AW, Haque E, Gadupudi GS, Robertson LW. Skeletal toxicity resulting from exposure of growing male rats to coplanar PCB 126 is associated with disruption of calcium homeostasis and the GH-IGF-1 axis and direct effects on bone formation. Arch Toxicol 2019; 94:389-399. [PMID: 31820026 DOI: 10.1007/s00204-019-02645-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 12/04/2019] [Indexed: 12/13/2022]
Abstract
Skeletal toxicity has been reported following exposure to polychlorinated biphenyl (PCB) mixtures. However, molecular mechanisms remain poorly understood. We exposed groups of male 4-5-week-old Sprague-Dawley rats to 3,3', 4, 4', 5-pentachlorobiphenyl (PCB 126), a dioxin-like coplanar PCB congener by a single i.p. injection of 5 µmol/kg in soy oil vehicle or vehicle alone. After 4 weeks, rats were euthanized. PCB exposure resulted in hypocalcemia (P < 0.05) and significant increases in serum PTH without changes in serum phosphorous. Hyperparathyroidism was accompanied by increased expression of mRNAs of vitamin D3 metabolizing cytochrome P450 enzymes CYP27B1 and CYP24 in the kidney (P < 0.05). PCB exposure also reduced body weight, serum IGF-1, and hepatic expression of mRNAs encoding the male-specific GH-pattern-regulated CYP2C11 and CYP3A2 relative to controls (P < 0.05). PCB exposure reduced long bone length, diameter, and surface area, but increased trabecular thickness and volume (P < 0.05). Serum osteocalcin (P < 0.05), a marker and a regulator of bone formation, was reduced, but PCB exposure had no effect on the bone resorption marker RatLaps. Exposure of human intestinal Caco-2 cells to 10-100 nM PCB 126 in the presence of vitamin D3 resulted in inhibition of mRNAs for the calcium transporters TRPV6 and PMCA1b (P < 0.05). In addition, PCB 126 suppressed osteoblastogenesis in primary bone marrow mesenchymal stem cell cultures which was blunted by the AhR antagonist CH-223191. These data provide novel evidence that skeletal toxicity after exposure to PCB 126 is a result of disruption of calcium homeostasis and the GH-IGF-1 axis, and involves direct AhR-mediated effects on bone formation.
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Affiliation(s)
- Martin J Ronis
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center-New Orleans, 1901 Perdido Str., New Orleans, LA, 70112, USA.
| | - James Watt
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center-New Orleans, 1901 Perdido Str., New Orleans, LA, 70112, USA
| | - Casey F Pulliam
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center-New Orleans, 1901 Perdido Str., New Orleans, LA, 70112, USA
| | - Ashlee E Williams
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center-New Orleans, 1901 Perdido Str., New Orleans, LA, 70112, USA
| | - Alexander W Alund
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Ezazul Haque
- IDGP in Human Toxicology and Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA, USA
| | - Gopi S Gadupudi
- IDGP in Human Toxicology and Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA, USA
| | - Larry W Robertson
- IDGP in Human Toxicology and Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA, USA
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Klaren WD, Vine D, Vogt S, Robertson LW. Spatial distribution of metals within the liver acinus and their perturbation by PCB126. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:16427-16433. [PMID: 28940161 PMCID: PMC5866157 DOI: 10.1007/s11356-017-0202-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 09/12/2017] [Indexed: 06/07/2023]
Abstract
Animal studies show that exposure to the environmental pollutant 3,3',4,4',5-pentachlorobiphenyl (PCB126) causes alterations in hepatic metals as measured in acid-digested volume-adjusted tissue. These studies lack the detail of the spatial distribution within the liver. Here we use X-ray fluorescence microscopy (XFM) to assess the spatial distribution of trace elements within liver tissue. Liver samples from male Sprague Dawley rats, treated either with vehicle or PCB126, were formalin fixed and paraffin embedded. Serial sections were prepared for traditional H&E staining or placed on silicon nitride windows for XFM. With XFM, metal gradients between the portal triad and the central vein were seen, especially with copper and iron. These gradients change with exposure to PCB126, even reverse. This is the first report of how micronutrients vary spatially within the liver and how they change in response to toxicant exposure. In addition, high concentrations of zinc clusters were discovered in the extracellular space. PCB126 treatment did not affect their presence, but did alter their elemental makeup suggesting a more general biological function. Further work is needed to properly evaluate the gradients and their alterations as well as classify the zinc clusters to determine their role in liver function and zinc homeostasis.
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Affiliation(s)
- William D Klaren
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, IA, USA
- Department of Occupational and Environmental Health, The University of Iowa, College of Public Health, 100 Oakdale Campus #219 IREH, Iowa City, IA, 52242-5000, USA
| | - David Vine
- Microscopy and X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, IL, USA
| | - Stefan Vogt
- Microscopy and X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, IL, USA
| | - Larry W Robertson
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, IA, USA.
- Department of Occupational and Environmental Health, The University of Iowa, College of Public Health, 100 Oakdale Campus #219 IREH, Iowa City, IA, 52242-5000, USA.
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Gadupudi GS, Elser BA, Sandgruber FA, Li X, Gibson-Corley KN, Robertson LW. PCB126 Inhibits the Activation of AMPK-CREB Signal Transduction Required for Energy Sensing in Liver. Toxicol Sci 2018; 163:440-453. [PMID: 29474705 PMCID: PMC5974782 DOI: 10.1093/toxsci/kfy041] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
3,3',4,4',5-pentachlorobiphenyl (PCB126), a dioxin-like PCB, elicits toxicity through a wide array of noncarcinogenic effects, including metabolic syndrome, wasting, and nonalcoholic fatty-liver disease. Previously, we reported decreases in the transcription of several enzymes involved in gluconeogenesis, before the early onset of lipid accumulation. Hence, this study was aimed at understanding the impact of resultant decreases gluconeogenic enzymes on growth, weight, and metabolism in the liver, upon extended exposure. Male Sprague Dawley rats (75-100 g), fed a defined AIN-93G diet, were injected (ip) with single dose of soy oil (5 ml/kg body weight; n = 14) or PCB126 (5 µmol/kg; n = 15), 28 days, prior euthanasia. A subset of rats from each group were fasted for 12 h (vehicle [n = 6] and PCB126 [n = 4]). Rats only showed significant weight loss between days 14 and 28 (p < .05) and some mortality (p = .0413). As in our previous studies, the expression levels of enzymes involved in gluconeogenesis (Pepck-c, G6Pase, Sds, Pc, and Ldh-A) and glycogenolysis (Pygl) were strongly downregulated. The decreased expression of these enzymes in PCB126-treated rats after a 12 h fast decreased hepatic glucose production from glycogen and gluconeogenic substrates, exacerbating the hypoglycemia. Additionally, PCB126 caused hepatic steatosis and decreased the expression of the transcription factor Pparα and its targets, necessary for fatty-acid oxidation. The observed metabolic disruption across multiple branches of fasting metabolism resulted from inhibition in the activation of enzyme AMPK and transcription factor CREB signaling, necessary for "sensing" energy-deprivation and the induction of enzymes that respond to the PCB126 triggered fuel crisis in liver.
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Affiliation(s)
- Gopi S Gadupudi
- Interdisciplinary Graduate Program in Human Toxicology, Graduate College, The University of Iowa, Iowa City, Iowa
- Department of Occupational and Environmental Health, College of Public Health
| | - Benjamin A Elser
- Interdisciplinary Graduate Program in Human Toxicology, Graduate College, The University of Iowa, Iowa City, Iowa
- Department of Occupational and Environmental Health, College of Public Health
| | - Fabian A Sandgruber
- Department of Occupational and Environmental Health, College of Public Health
| | - Xueshu Li
- Department of Occupational and Environmental Health, College of Public Health
| | | | - Larry W Robertson
- Interdisciplinary Graduate Program in Human Toxicology, Graduate College, The University of Iowa, Iowa City, Iowa
- Department of Occupational and Environmental Health, College of Public Health
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Wu X, Yang J, Morisseau C, Robertson LW, Hammock B, Lehmler HJ. 3,3',4,4',5-Pentachlorobiphenyl (PCB 126) Decreases Hepatic and Systemic Ratios of Epoxide to Diol Metabolites of Unsaturated Fatty Acids in Male Rats. Toxicol Sci 2016; 152:309-22. [PMID: 27208083 PMCID: PMC4960907 DOI: 10.1093/toxsci/kfw084] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Disruption of the homeostasis of oxygenated regulatory lipid mediators (oxylipins), potential markers of exposure to aryl hydrocarbon receptor (AhR) agonists, such as 3,3',4,4',5-pentachlorobiphenyl (PCB 126), is associated with a range of diseases, including nonalcoholic fatty liver disease and nonalcoholic steatohepatitis. Here we test the hypothesis that PCB 126 exposure alters the levels of oxylipins in rats. Male Sprague-Dawley rats (5-weeks old) were treated over a 3-month period every 2 weeks with intraperitoneal injections of PCB 126 in corn oil (cumulative doses of 0, 19.8, 97.8, and 390 µg/kg b.w.; 6 injections total). PCB 126 treatment caused a reduction in growth rates at the highest dose investigated, a dose-dependent decrease in thymus weights, and a dose-dependent increase in liver weights. Liver PCB 126 levels increased in a dose-dependent manner, while levels in plasma were below or close to the detection limit. The ratios of several epoxides to diol metabolites formed via the cytochrome P450 (P450) monooxygenase/soluble epoxide hydrolase (sEH) pathway from polyunsaturated fatty acids displayed a dose-dependent decrease in the liver and plasma, whereas levels of oxylipins formed by other metabolic pathways were generally not altered by PCB 126 treatment. The effects of PCB 126 on epoxide-to-diol ratios were associated with an increased CYP1A activity in liver microsomes and an increased sEH activity in liver cytosol and peroxisomes. These results suggest that oxylipins are potential biomarkers of exposure to PCB 126 and that the P450/sEH pathway is a therapeutic target for PCB 126-mediated hepatotoxicity that warrants further attention.
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Affiliation(s)
- Xianai Wu
- *Department of Occupational and Environmental Health, College of Public Health, The University of Iowa, Iowa City, Iowa
| | - Jun Yang
- Department of Entomology and Nematology, UC Davis Comprehensive Cancer Center, University of California, Davis, California
| | - Christophe Morisseau
- Department of Entomology and Nematology, UC Davis Comprehensive Cancer Center, University of California, Davis, California
| | - Larry W Robertson
- *Department of Occupational and Environmental Health, College of Public Health, The University of Iowa, Iowa City, Iowa
| | - Bruce Hammock
- Department of Entomology and Nematology, UC Davis Comprehensive Cancer Center, University of California, Davis, California
| | - Hans-Joachim Lehmler
- *Department of Occupational and Environmental Health, College of Public Health, The University of Iowa, Iowa City, Iowa
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Long-term in vivo polychlorinated biphenyl 126 exposure induces oxidative stress and alters proteomic profile on islets of Langerhans. Sci Rep 2016; 6:27882. [PMID: 27292372 PMCID: PMC4904407 DOI: 10.1038/srep27882] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 05/24/2016] [Indexed: 12/15/2022] Open
Abstract
It has been recently proposed that exposure to polychlorinated biphenyls (PCBs) is a risk factor to type 2 diabetes mellitus (DM2). We investigated this hypothesis using long-term in vivo PCB126 exposure to rats addressing metabolic, cellular and proteomic parameters. Male Wistar rats were exposed to PCB126 (0.1, 1 or 10 μg/kg of body weight/day; for 15 days) or vehicle by intranasal instillation. Systemic alterations were quantified by body weight, insulin and glucose tolerance, and blood biochemical profile. Pancreatic toxicity was measured by inflammatory parameters, cell viability and cycle, free radical generation, and proteomic profile on islets of Langerhans. In vivo PCB126 exposure enhanced the body weight gain, impaired insulin sensitivity, reduced adipose tissue deposit, and elevated serum triglycerides, cholesterol, and insulin levels. Inflammatory parameters in the pancreas and cell morphology, viability and cycle were not altered in islets of Langerhans. Nevertheless, in vivo PCB126 exposure increased free radical generation and modified the expression of proteins related to oxidative stress on islets of Langerhans, which are indicative of early β-cell failure. Data herein obtained show that long-term in vivo PCB126 exposure through intranasal route induced alterations on islets of Langerhans related to early end points of DM2.
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Klaren WD, Gibson-Corley KN, Wels B, Simmons DL, McCormick ML, Spitz DR, Robertson LW. Assessment of the Mitigative Capacity of Dietary Zinc on PCB126 Hepatotoxicity and the Contribution of Zinc to Toxicity. Chem Res Toxicol 2016; 29:851-9. [PMID: 26967026 DOI: 10.1021/acs.chemrestox.6b00022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Hepatic levels of the essential micronutrient, zinc, are diminished by several hepatotoxicants, and the dietary supplementation of zinc has proven protective in those cases. 3,3',4,4',5-Pentachlorobiphenyl (PCB126), a liver toxicant, alters hepatic nutrient homeostasis and lowers hepatic zinc levels. The current study was designed to determine the mitigative potential of dietary zinc in the toxicity associated with PCB126 and the role of zinc in that toxicity. Male Sprague-Dawley rats were divided into three dietary groups and fed diets deficient in zinc (7 ppm Zn), adequate in zinc (30 ppm Zn), and supplemented in zinc (300 ppm). The animals were maintained for 3 weeks on these diets, then given a single IP injection of vehicle or 1 or 5 μmol/kg PCB126. After 2 weeks, the animals were euthanized. Dietary zinc increased the level of ROS, the activity of CuZnSOD, and the expression of metallothionein but decreased the levels of hepatic manganese. PCB126 exposed rats exhibited classic signs of exposure, including hepatomegaly, increased hepatic lipids, increased ROS and CYP induction. Liver histology suggests some mild ameliorative properties of both zinc deficiency and zinc supplementation. Other metrics of toxicity (relative liver and thymus weights, hepatic lipids, and hepatic ROS) did not support this trend. Interestingly, the zinc supplemented high dose PCB126 group had mildly improved histology and less efficacious induction of investigated genes than did the low dose PCB126 group. Overall, decreases in zinc caused by PCB126 likely contribute little to the ongoing toxicity, and the mitigative/preventive capacity of zinc against PCB126 exposure seems limited.
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Affiliation(s)
- William D Klaren
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa , Iowa City, Iowa 52242, United States.,Department of Occupational and Environmental Health, College of Public Health, University of Iowa , Iowa City, Iowa 52242, United States
| | | | - Brian Wels
- State Hygienic Laboratory, University of Iowa , Ankeny, Iowa 50023, United States
| | - Donald L Simmons
- State Hygienic Laboratory, University of Iowa , Ankeny, Iowa 50023, United States
| | - Michael L McCormick
- Free Radical and Radiation Biology Program, University of Iowa Carver College of Medicine , Iowa City, Iowa 52242, United States
| | - Douglas R Spitz
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa , Iowa City, Iowa 52242, United States.,Free Radical and Radiation Biology Program, University of Iowa Carver College of Medicine , Iowa City, Iowa 52242, United States
| | - Larry W Robertson
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa , Iowa City, Iowa 52242, United States.,Department of Occupational and Environmental Health, College of Public Health, University of Iowa , Iowa City, Iowa 52242, United States
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Liu Z, Wu X, Zhang T, Cui H, Guo J, Guo Q, Gao X, Yang F. Influence of dietary copper concentrations on growth performance, serum lipid profiles, antioxidant defenses, and fur quality in growing–furring male blue foxes (Vulpes lagopus)1. J Anim Sci 2016; 94:1095-104. [DOI: 10.2527/jas.2015-9960] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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9
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Li M, Teesch LM, Murry DJ, Pope RM, Li Y, Robertson LW, Ludewig G. Cytochrome c adducts with PCB quinoid metabolites. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:2148-59. [PMID: 26062463 PMCID: PMC4676959 DOI: 10.1007/s11356-015-4801-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2015] [Accepted: 05/27/2015] [Indexed: 04/15/2023]
Abstract
Polychlorinated biphenyls (PCBs) are a group of 209 individual congeners widely used as industrial chemicals. PCBs are found as by-products in dye and paint manufacture and are legacy, ubiquitous, and persistent as human and environmental contaminants. PCBs with fewer chlorine atoms may be metabolized to hydroxy- and dihydroxy-metabolites and further oxidized to quinoid metabolites both in vitro and in vivo. Specifically, quinoid metabolites may form adducts on nucleophilic sites within cells. We hypothesized that the PCB-quinones covalently bind to cytochrome c and, thereby, cause defects in the function of cytochrome c. In this study, synthetic PCB quinones, 2-(4'-chlorophenyl)-1,4-benzoquinone (PCB3-pQ), 4-4'-chlorophenyl)-1,2-benzoquinone (PCB3-oQ), 2-(3', 5'-dichlorophenyl)-1,4-benzoquinone, 2-(3',4', 5'-trichlorophenyl)-1,4-benzoquinone, and 2-(4'-chlorophenyl)-3,6-dichloro-1,4-benzoquinone, were incubated with cytochrome c, and adducts were detected by liquid chromatography-mass spectrometry (LC-MS) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI TOF). Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was employed to separate the adducted proteins, while trypsin digestion and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were applied to identify the amino acid binding sites on cytochrome c. Conformation change of cytochrome c after binding with PCB3-pQ was investigated by SYBYL-X simulation and cytochrome c function was examined. We found that more than one molecule of PCB-quinone may bind to one molecule of cytochrome c. Lysine and glutamic acid were identified as the predominant binding sites. Software simulation showed conformation changes of adducted cytochrome c. Additionally, cross-linking of cytochrome c was observed on the SDS-PAGE gel. Cytochrome c was found to lose its function as electron acceptor after incubation with PCB quinones. These data provide evidence that the covalent binding of PCB quinone metabolites to cytochrome c may be included among the toxic effects of PCBs.
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Affiliation(s)
- Miao Li
- Interdisciplinary Graduate Program in Human Toxicology, Graduate College, The University of Iowa, Iowa City, IA, USA
- Department of Occupational & Environmental Health, College of Public Health, The University of Iowa, 100 Oakdale Campus 214 IREH, Iowa City, IA, 52242-5000, USA
| | - Lynn M Teesch
- High Resolution Mass Spectrometry Facility, The University of Iowa, Iowa City, IA, USA
| | - Daryl J Murry
- Interdisciplinary Graduate Program in Human Toxicology, Graduate College, The University of Iowa, Iowa City, IA, USA
- College of Pharmacy, The University of Iowa, Iowa City, IA, USA
| | - R Marshal Pope
- Proteomics Facility, The University of Iowa, Iowa City, IA, USA
| | - Yalan Li
- Proteomics Facility, The University of Iowa, Iowa City, IA, USA
| | - Larry W Robertson
- Interdisciplinary Graduate Program in Human Toxicology, Graduate College, The University of Iowa, Iowa City, IA, USA
- Department of Occupational & Environmental Health, College of Public Health, The University of Iowa, 100 Oakdale Campus 214 IREH, Iowa City, IA, 52242-5000, USA
| | - Gabriele Ludewig
- Interdisciplinary Graduate Program in Human Toxicology, Graduate College, The University of Iowa, Iowa City, IA, USA.
- Department of Occupational & Environmental Health, College of Public Health, The University of Iowa, 100 Oakdale Campus 214 IREH, Iowa City, IA, 52242-5000, USA.
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Klaren WD, Flor S, Gibson-Corley KN, Ludewig G, Robertson LW. Metallothionein's role in PCB126 induced hepatotoxicity and hepatic micronutrient disruption. Toxicol Rep 2016; 3:21-28. [PMID: 26770886 PMCID: PMC4710377 DOI: 10.1016/j.toxrep.2015.12.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Polychlorinated biphenyls (PCBs), industrial chemicals and persistent environmental pollutants, are found in rural and urban settings. Rodent studies have shown that exposure to PCB126, a dioxin-like PCB, causes a significant disruption of hepatic micronutrient homeostasis and an increase in metallothionein (MT), an antioxidant protein and metal carrier. A MT knockout mouse strain was used to assess metallothionein’s role in micronutrient disruption and overall hepatotoxicity. Twenty four 129S male mice (12 wild type (WT) and 12 MT knockout (MTKO)) were placed on a purified diet (AIN-93G) for 3 weeks to achieve hepatic metal equilibrium. Mice were then given a single IP injection of either vehicle or 150 μmol/kg PCB126 in vehicle. The animals were sacrificed 2 weeks later and organs processed for analysis. Liver histology, hepatic lipids, gene expression, micronutrient and ROS status were investigated. Liver weights, liver lipids, ROS, and hepatocyte vacuolation were increased with PCB126 exposure along with AhR responsive genes. The MTKO animals had more severe histological changes in the liver and elevated liver lipids than their wild type counterparts. Hepatic and renal metals levels (Cu, Zn, Se and Mn) were mostly reduced by PCB126 treatment. Renal micronutrients were more affected by PCB126 treatment in the MTKO animals. This research suggests that MT may not be the sole/primary cause of the metal disruption caused by PCB126 exposure in mice, but may provide protection against overall hepatotoxicity.
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Affiliation(s)
- W D Klaren
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, Iowa; Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa
| | - S Flor
- Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa
| | | | - G Ludewig
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, Iowa; Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa
| | - L W Robertson
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, Iowa; Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa
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Wang B, Klaren WD, Wels BR, Simmons DL, Olivier AK, Wang K, Robertson LW, Ludewig G. Dietary Manganese Modulates PCB126 Toxicity, Metal Status, and MnSOD in the Rat. Toxicol Sci 2015; 150:15-26. [PMID: 26660635 DOI: 10.1093/toxsci/kfv312] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PCB126 (3,3',4,4',5-pentachlorobiphenyl) is a potent aryl hydrocarbon receptor agonist and induces oxidative stress. Because liver manganese (Mn) levels decrease in response to PCB126, a Mn dietary study was designed to investigate the role of Mn in PCB126 toxicity. Male Sprague Dawley rats received diets containing 0, 10, or 150 ppm added Mn for 3 weeks, followed by a single ip injection of corn oil or PCB126 (5 µmol/kg body weight). After 2 weeks, Mn, Cu, Zn, and Fe levels in the heart, liver, and liver mitochondria, and Mn-containing superoxide dismutase (MnSOD) and metallothionein mRNA, MnSOD protein, and MnSOD activity were determined. Mn levels in liver, heart, and liver mitochondria were strongly decreased by the Mn-deficient diet. Small effects on Fe levels and a stepwise increase in MnSOD activity with dietary Mn were also visible. PCB126 caused profound changes in Cu (up), Zn, Fe, and Mn (down) in liver, but not in heart, and differing effects (Cu, Zn, and Fe up, Mn down) in liver mitochondria. Liver MnSOD and metallothionein mRNA levels and MnSOD protein were increased but MnSOD activity was decreased by PCB126. PCB126-induced liver enlargement was dose-dependently reduced with increasing dietary Mn. These changes in metals homeostasis and MnSOD activity in liver but not heart may be a/the mechanism of PCB126 liver-specific toxicity. Specifically, transport of Fenton metals (Cu, Fe) into and Mn out of the mitochondria, a probable mechanism for lower MnSOD activity, may be a/the cause of PCB126-induced oxidative stress. The role of metallothioneins needs further evaluation. Dietary Mn slightly alleviated PCB126-induced toxicities.
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Affiliation(s)
- Bingxuan Wang
- *The Interdisciplinary Graduate Program in Human Toxicology and
| | | | - Brian R Wels
- State Hygienic Laboratory, The University of Iowa, Iowa City, Iowa
| | - Donald L Simmons
- State Hygienic Laboratory, The University of Iowa, Iowa City, Iowa
| | - Alicia K Olivier
- Department of Pathobiology and Population Medicine, Mississippi State University College of Veterinary Medicine, Statesville, Mississippi
| | | | - Larry W Robertson
- *The Interdisciplinary Graduate Program in Human Toxicology and Department of Occupational and Environmental Health, College of Public Health, The University of Iowa, Iowa City, Iowa
| | - Gabriele Ludewig
- *The Interdisciplinary Graduate Program in Human Toxicology and Department of Occupational and Environmental Health, College of Public Health, The University of Iowa, Iowa City, Iowa.
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Klaren WD, Gadupudi GS, Wels B, Simmons DL, Olivier AK, Robertson LW. Progression of micronutrient alteration and hepatotoxicity following acute PCB126 exposure. Toxicology 2015; 338:1-7. [PMID: 26410179 DOI: 10.1016/j.tox.2015.09.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 09/16/2015] [Accepted: 09/22/2015] [Indexed: 11/26/2022]
Abstract
Polychlorinated Biphenyls (PCBs) are industrial chemicals that have become a persistent threat to human health due to ongoing exposure. A subset of PCBs, known as dioxin-like PCBs, pose a special threat given their potent hepatic effects. Micronutrients, especially Cu, Zn and Se, homeostatic dysfunction is commonly seen after exposure to dioxin-like PCBs. This study investigates whether micronutrient alteration is the byproduct of the ongoing hepatotoxicity, marked by lipid accumulation, or a concurrent, yet independent event of hepatic damage. A time course study was carried out using male Sprague-Dawley rats with treatments of PCB126, the prototypical dioxin-like PCB, resulting in 6 different time points. Animals were fed a purified diet, based on AIN-93G, for three weeks to ensure micronutrient equilibration. A single IP injection of either tocopherol-stripped soy oil vehicle (5 mL/kg) or 5 μmol/kg PCB126 dose in vehicle was given at various time points resulting in exposures of 9h, 18 h, 36 h, 3 days, 6 days, and 12 days. Mild hepatic vacuolar change was seen as early as 36 h with drastic changes at the later time points, 6 and 12 days. Micronutrient alterations, specifically Cu, Zn, and Se, were not seen until after day 3 and only observed in the liver. No alterations were seen in the duodenum, suggesting that absorption and excretion may not be involved. Micronutrient alterations occur with ROS formation, lipid accumulation, and hepatomegaly. To probe the mechanistic underpinnings, alteration of gene expression of several copper chaperones was investigated; only metallothionein appeared elevated. These data suggest that the disruption in micronutrient status is a result of the hepatic injury elicited by PCB126 and is mediated in part by metallothionein.
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Affiliation(s)
- W D Klaren
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, Iowa, USA; Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa, USA
| | - G S Gadupudi
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, Iowa, USA; Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa, USA
| | - B Wels
- State Hygienic Laboratory, University of Iowa, Ankeny, Iowa, USA
| | - D L Simmons
- State Hygienic Laboratory, University of Iowa, Ankeny, Iowa, USA
| | - A K Olivier
- Department of Pathology, University of Iowa, Iowa City, Iowa, USA
| | - L W Robertson
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, Iowa, USA; Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa, USA.
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Buha A, Antonijević B, Milovanović V, Janković S, Bulat Z, Matović V. Polychlorinated biphenyls as oxidative stress inducers in liver of subacutely exposed rats: implication for dose-dependence toxicity and benchmark dose concept. ENVIRONMENTAL RESEARCH 2015; 136:309-317. [PMID: 25460651 DOI: 10.1016/j.envres.2014.11.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 10/29/2014] [Accepted: 11/06/2014] [Indexed: 06/04/2023]
Abstract
Hepatotoxicity is one of the well-documented adverse health effects of polychlorinated biphenyls (PCBs)-persistent organic pollutants widely present in the environment. Although previous studies suggest possible role of oxidative stress, the precise mechanisms of PCB-induced ROS production in liver still remain to be fully assessed. The aim of this study was to evaluate the effects of different doses of PCBs on the parameters of oxidative stress and to investigate whether these effects are dose dependent. Furthermore, a comparison between calculated benchmark doses (BMD) and estimated NOAEL values for investigated parameters, was made. Six groups of male albino Wistar rats (7 animals per group) were receiving Aroclor 1254 dissolved in corn oil in the doses of 0.5, 1, 2, 4, 8, 16 mg PCBs/kg b.w./day by oral gavage during 28 days while control animals were receiving corn oil only. The following parameters of oxidative stress were analyzed in liver homogenates: superoxide dismutase activity, glutathione, malondialdehyde (MDA) and total protein thiol levels. Hepatic enzymes AST, ALT, ALP and protein albumin were also determined in serum as clinical parameters of liver function. Collected data on the investigated parameters were analyzed by the BMD method. The results of this study demonstrate that subacute exposure to PCBs causes induction of oxidative stress in liver with dose-dependent changes of the investigated parameters, although more pronounced adverse effects were observed on enzymatic than on non-enzymatic components of antioxidant protection. The obtained values for BMD and NOAEL support the use of BMD concept in the prediction of health risks associated with PCBs exposure. Furthermore, our results implicate possible use of MDA in PCBs risk assessment, since MDA was the most sensitive investigated parameter with calculated low critical effect dose of 0.07 mg/kg b.w.
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Affiliation(s)
- Aleksandra Buha
- Department of Toxicology "Akademik Danilo Soldatović", University of Belgrade-Faculty of Pharmacy, Belgrade, Serbia.
| | - Biljana Antonijević
- Department of Toxicology "Akademik Danilo Soldatović", University of Belgrade-Faculty of Pharmacy, Belgrade, Serbia
| | - Vesna Milovanović
- Chemicals Department, Ministry of Agriculture and Environmental Protection of Republic of Serbia, Belgrade, Serbia
| | - Saša Janković
- Institute of Meat Hygiene and Technology, Belgrade, Serbia
| | - Zorica Bulat
- Department of Toxicology "Akademik Danilo Soldatović", University of Belgrade-Faculty of Pharmacy, Belgrade, Serbia
| | - Vesna Matović
- Department of Toxicology "Akademik Danilo Soldatović", University of Belgrade-Faculty of Pharmacy, Belgrade, Serbia
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