1
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Wang J, Lu P, Xie W. Atypical functions of xenobiotic receptors in lipid and glucose metabolism. MEDICAL REVIEW (2021) 2022; 2:611-624. [PMID: 36785576 PMCID: PMC9912049 DOI: 10.1515/mr-2022-0032] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 11/08/2022] [Indexed: 12/02/2022]
Abstract
Xenobiotic receptors are traditionally defined as xenobiotic chemical-sensing receptors, the activation of which transcriptionally regulates the expression of enzymes and transporters involved in the metabolism and disposition of xenobiotics. Emerging evidence suggests that "xenobiotic receptors" also have diverse endobiotic functions, including their effects on lipid metabolism and energy metabolism. Dyslipidemia is a major risk factor for cardiovascular disease, diabetes, obesity, metabolic syndrome, stroke, nonalcoholic fatty liver disease (NAFLD), and nonalcoholic steatohepatitis (NASH). Understanding the molecular mechanism by which transcriptional factors, including the xenobiotic receptors, regulate lipid homeostasis will help to develop preventive and therapeutic approaches. This review describes recent advances in our understanding the atypical roles of three xenobiotic receptors: aryl hydrocarbon receptor (AhR), pregnane X receptor (PXR), and constitutive androstane receptor (CAR), in metabolic disorders, with a particular focus on their effects on lipid and glucose metabolism. Collectively, the literatures suggest the potential values of AhR, PXR and CAR as therapeutic targets for the treatment of NAFLD, NASH, obesity and diabetes, and cardiovascular diseases.
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Affiliation(s)
- Jingyuan Wang
- Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Peipei Lu
- Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Wen Xie
- Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
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2
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Fernández-Martos S, Calvo-Sánchez MI, Lobo-Aldezabal A, Sánchez-Adrada AI, Moreno C, Vitale M, Espada J. The deleterious effects induced by an acute exposure of human skin to common air pollutants are prevented by extracts of Deschampsia antarctica. Sci Rep 2021; 11:23751. [PMID: 34887500 PMCID: PMC8660883 DOI: 10.1038/s41598-021-03190-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 11/22/2021] [Indexed: 11/09/2022] Open
Abstract
The homeostatic and regenerative potential of the skin is critically impaired by an increasing accumulation of air pollutants in human ecosystems. These toxic compounds are frequently implicated in pathological processes such as premature cutaneous ageing, altered pigmentation and cancer. In this scenario, innovative strategies are required to tackle the effects of severe air pollution on skin function. Here we have used a Human Skin Organotypic Culture (HSOC) model to characterize the deleterious effects of an acute topic exposure of human skin to moderately high concentrations of common ambient pollutants, including As, Cd, Cr, dioxins and tobacco smoke. All these toxic compunds inflict severe damage in the tissue, activating the AHR-mediated response to xenobiotics. We have further evaluated the potential of an aqueous leaf extract of the polyextremophile plant Deschampsia antarctica (Edafence) to protect human skin against the acute exposure to toxic pollutants. Our results indicate that pre-treatment of HSOC samples with this aqueous extract conuterbalances the deleterious effects of the exposure to toxic comunds and triggers the activation of key genes invoved in the redox system and in the pro-inflammatory/wound healing response in the skin, suggesting that this natural compound might be effectively used in vivo to protect human skin routinely in different daily conditions.
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Affiliation(s)
- Sandra Fernández-Martos
- Experimental Dermatology and Skin Biology Group, Ramon y Cajal Institute for Health Research (IRYCIS), Ramón y Cajal University Hospital, Madrid, Spain
| | - María I Calvo-Sánchez
- Experimental Dermatology and Skin Biology Group, Ramon y Cajal Institute for Health Research (IRYCIS), Ramón y Cajal University Hospital, Madrid, Spain
- Biosciences Research Institute, School of Experimental Sciences, Universidad Francisco de Vitoria, UFV, Building E, Ctra. M-515 Pozuelo-Majadahonda Km 1,800, 28223, Pozuelo de Alarcón, Madrid, Spain
| | - Ana Lobo-Aldezabal
- Experimental Dermatology and Skin Biology Group, Ramon y Cajal Institute for Health Research (IRYCIS), Ramón y Cajal University Hospital, Madrid, Spain
- Biosciences Research Institute, School of Experimental Sciences, Universidad Francisco de Vitoria, UFV, Building E, Ctra. M-515 Pozuelo-Majadahonda Km 1,800, 28223, Pozuelo de Alarcón, Madrid, Spain
| | | | - Carmen Moreno
- Anatomic Pathology Service, Ramón y Cajal University Hospital, Madrid, Spain
| | - María Vitale
- Medical Affairs Department, Cantabria Labs, Madrid, Spain
| | - Jesús Espada
- Experimental Dermatology and Skin Biology Group, Ramon y Cajal Institute for Health Research (IRYCIS), Ramón y Cajal University Hospital, Madrid, Spain.
- Centro Integrativo de Biología y Química Aplicada (CIBQA), Universidad Bernardo O'Higgins, Santiago, Chile.
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3
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Lay JO, Liyanage R, Gidden JA. THE DEVELOPMENT OF A HIGH-RESOLUTION MASS SPECTROMETRY METHOD FOR ULTRA-TRACE ANALYSIS OF CHLORINATED DIOXINS IN ENVIRONMENTAL AND BIOLOGICAL SAMPLES INCLUDING VIET NAM ERA VETERANS. MASS SPECTROMETRY REVIEWS 2021; 40:236-254. [PMID: 32530096 DOI: 10.1002/mas.21639] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 05/19/2020] [Accepted: 05/26/2020] [Indexed: 06/11/2023]
Abstract
Chlorinated dioxins are labeled and recognized by both the World Health Organization and the United Nations Environmental Programme (UNEP) as "persistent organic pollutants". Their potential for high toxicity is one of the primary factors behind intense public and regulatory scrutiny and the need to measure the compounds at very low limits, specifically the isomer 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD). This article highlights the early mass spectrometry methods to investigate, detect, confirm, and quantify chlorinated dioxins and the initial applications involving human biomonitoring, as attempts were made to attribute health effects to TCDD exposure. This effort represented a complex and difficult scientific response to the pressing need to investigate expected exposures and alleged subsequent medical effects, which in the case of the Viet Nam veterans was being attempted a decade or more after their exposure. It is noteworthy that this method and its development touched on delicate issues involving human subjects, war veterans, environmental contamination, and was difficult not only scientifically, but for ethical and political reasons as well. Stable-isotope dilution with analysis by gas chromatography/high-resolution mass spectrometry (GC/HRMS) became the method of choice because of its ability to monitor characteristic ions and isotope ratios to quantify and qualify/confirm the analyte in the presence of coextracting and coeluting interferences at these low levels with the highest possible confidence. This method was rigorously tested and validated before it was used to discover and monitor levels in the environment and in various populations at then unprecedented low levels. These early studies demonstrated the feasibility of monitoring dioxins in humans even decades after exposure, and led to the detection of 2,3,7,8-TCDD in the general population as well as specific overexposed populations. These studies also provided strong evidence regarding the origins of the 2,3,7,8-isomer in the environment. © 2020 John Wiley & Sons Ltd. Mass Spec Rev.
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Affiliation(s)
- Jackson O Lay
- Department of Chemistry and Biochemistry, Arkansas Statewide Mass Spectrometry Facility, University of Arkansas, Fayetteville, Arkansas, 72701
| | - Rohana Liyanage
- Department of Chemistry and Biochemistry, Arkansas Statewide Mass Spectrometry Facility, University of Arkansas, Fayetteville, Arkansas, 72701
| | - Jennifer A Gidden
- Department of Chemistry and Biochemistry, Arkansas Statewide Mass Spectrometry Facility, University of Arkansas, Fayetteville, Arkansas, 72701
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4
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Trajectory Shifts in Interdisciplinary Research of the Aryl Hydrocarbon Receptor-A Personal Perspective on Thymus and Skin. Int J Mol Sci 2021; 22:ijms22041844. [PMID: 33673338 PMCID: PMC7918350 DOI: 10.3390/ijms22041844] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/08/2021] [Accepted: 02/10/2021] [Indexed: 12/13/2022] Open
Abstract
Identifying historical trajectories is a useful exercise in research, as it helps clarify important, perhaps even “paradigmatic”, shifts in thinking and moving forward in science. In this review, the development of research regarding the role of the transcription factor “aryl hydrocarbon receptor” (AHR) as a mediator of the toxicity of environmental pollution towards a link between the environment and a healthy adaptive response of the immune system and the skin is discussed. From this fascinating development, the opportunities for targeting the AHR in the therapy of many diseases become clear.
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5
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Bock KW. Aryl hydrocarbon receptor (AHR)-mediated inflammation and resolution: Non-genomic and genomic signaling. Biochem Pharmacol 2020; 182:114220. [PMID: 32941865 DOI: 10.1016/j.bcp.2020.114220] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 09/07/2020] [Accepted: 09/10/2020] [Indexed: 12/17/2022]
Abstract
Inflammation, an old medical problem, is being recognized as an active, well orchestrated biological process. When dysregulated, chronic inflammation may ensue, leading to tissue-dependent diseases. Depending upon the ligand and cellular context, aryl hydrocarbon receptor (AHR) may accelerate or attenuate inflammation and subsequent resolution. Three examples are discussed in which AHR modulates inflammation by a mixture of genomic and non-genomic signaling pathways: (i) AHR-agonistic bacterial virulence factors are leading to both microbial defense and resolution of inflammatory responses. (ii) TCDD-mediated persistent AHR activation initially leads to inflammation by non-genomic signaling, and may potentially lead to chronic inflammation. (iii) AHR may modulate anti-inflammatory actions in obesity-mediated non-alcoholic fatty liver disease (NAFLD): Hepatic lipotoxicity triggers generation of danger-associated molecular patterns (DAMPs) that facilitate the development of hepatitis. AHR is mainly involved in the resolution phase by induction of lipoxin A4 and Il-22. Moderate AHR activation by phytochemicals and microbial AHR ligands may facilitate resolution. In control of inflammation, AHR appears to integrate environmental conditions with coordinated cellular functions.
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Affiliation(s)
- Karl Walter Bock
- Institute of Experimental and Clinical Pharmacology and Toxicology, Wilhelmstrasse 56, D-72074 Tübingen, Germany.
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6
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Petriello MC, Brandon JA, Hoffman J, Wang C, Tripathi H, Abdel-Latif A, Ye X, Li X, Yang L, Lee E, Soman S, Barney J, Wahlang B, Hennig B, Morris AJ. Dioxin-like PCB 126 Increases Systemic Inflammation and Accelerates Atherosclerosis in Lean LDL Receptor-Deficient Mice. Toxicol Sci 2019; 162:548-558. [PMID: 29216392 DOI: 10.1093/toxsci/kfx275] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Exposure to dioxins and related persistent organic pollutants likely contributes to cardiovascular disease (CVD) risk through multiple mechanisms including the induction of chronic inflammation. Epidemiological studies have shown that leaner individuals may be more susceptible to the detrimental effects of lipophilic toxicants because they lack large adipose tissue depots that can accumulate and sequester these pollutants. This phenomenon complicates efforts to study mechanisms of pollutant-accelerated atherosclerosis in experimental animal models where high-fat feeding and adipose expansion limit the bioavailability of lipophilic pollutants. Here, we investigated whether a model dioxin-like pollutant, PCB 126, could increase inflammation and accelerate atherosclerosis in Ldlr-/- mice fed a low-fat atherogenic diet. We fed Ldlr-/- mice the Clinton/Cybulsky diet (10% kcal fat, 0.15% cholesterol) and sacrificed mice at 8, 10, or 12 weeks postPCB (2 doses of 1 μmol/kg) or vehicle gavage. To characterize this novel model, we examined the effects of PCB 126 on markers of systemic inflammation, hematological indices, fatty livers, and atherosclerotic lesion size. Mice exposed to PCB 126 exhibited significantly increased plasma inflammatory cytokine levels, increased circulating biomarkers of CVD, altered platelet, and red blood cell counts, increased accumulation of hepatic fatty acids, and accelerated atherosclerotic lesion formation in the aortic root. PCB 126 also increased circulating neutrophils, monocytes, and macrophages as determined by flow cytometry analysis. Exposure to dioxin-like PCB 126 increases inflammation and accelerates atherosclerosis in mice. This low-fat atherogenic diet may provide a useful tool to study the mechanisms linking exposure to lipophilic pollutants to increased risk of CVD.
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Affiliation(s)
- Michael C Petriello
- Division of Cardiovascular Medicine, College of Medicine.,Superfund Research Center, University of Kentucky, Lexington, Kentucky 40536.,Lexington Veterans Affairs Medical Center, Lexington, Kentucky 40502
| | | | - Jessie Hoffman
- Superfund Research Center, University of Kentucky, Lexington, Kentucky 40536.,Department of Pharmacology and Nutritional Sciences, College of Medicine
| | - Chunyan Wang
- Superfund Research Center, University of Kentucky, Lexington, Kentucky 40536.,Department of Animal and Food Sciences, College of Agriculture Food and Environment
| | - Himi Tripathi
- Gill Heart and Vascular Institute and Division of Cardiovascular Medicine
| | - Ahmed Abdel-Latif
- Gill Heart and Vascular Institute and Division of Cardiovascular Medicine
| | - Xiang Ye
- Department of Physiology, Saha Cardiovascular Research Center
| | - Xiangan Li
- Department of Physiology, Saha Cardiovascular Research Center
| | - Liping Yang
- Division of Cardiovascular Medicine, College of Medicine
| | - Eun Lee
- Department of Pathology and Laboratory Medicine, College of Medicine, University of Kentucky, Lexington, Kentucky 40536
| | - Sony Soman
- Division of Cardiovascular Medicine, College of Medicine.,Superfund Research Center, University of Kentucky, Lexington, Kentucky 40536.,Lexington Veterans Affairs Medical Center, Lexington, Kentucky 40502
| | - Jazmyne Barney
- Superfund Research Center, University of Kentucky, Lexington, Kentucky 40536
| | - Banrida Wahlang
- Superfund Research Center, University of Kentucky, Lexington, Kentucky 40536
| | - Bernhard Hennig
- Superfund Research Center, University of Kentucky, Lexington, Kentucky 40536.,Department of Animal and Food Sciences, College of Agriculture Food and Environment
| | - Andrew J Morris
- Division of Cardiovascular Medicine, College of Medicine.,Superfund Research Center, University of Kentucky, Lexington, Kentucky 40536.,Lexington Veterans Affairs Medical Center, Lexington, Kentucky 40502
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7
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Tuomisto J. Dioxins and dioxin-like compounds: toxicity in humans and animals, sources, and behaviour in the environment. WIKIJOURNAL OF MEDICINE 2019. [DOI: 10.15347/wjm/2019.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2022] Open
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8
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Knutsen HK, Alexander J, Barregård L, Bignami M, Brüschweiler B, Ceccatelli S, Cottrill B, Dinovi M, Edler L, Grasl-Kraupp B, Hogstrand C, Nebbia CS, Oswald IP, Petersen A, Rose M, Roudot AC, Schwerdtle T, Vleminckx C, Vollmer G, Wallace H, Fürst P, Håkansson H, Halldorsson T, Lundebye AK, Pohjanvirta R, Rylander L, Smith A, van Loveren H, Waalkens-Berendsen I, Zeilmaker M, Binaglia M, Gómez Ruiz JÁ, Horváth Z, Christoph E, Ciccolallo L, Ramos Bordajandi L, Steinkellner H, Hoogenboom LR. Risk for animal and human health related to the presence of dioxins and dioxin-like PCBs in feed and food. EFSA J 2018; 16:e05333. [PMID: 32625737 PMCID: PMC7009407 DOI: 10.2903/j.efsa.2018.5333] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The European Commission asked EFSA for a scientific opinion on the risks for animal and human health related to the presence of dioxins (PCDD/Fs) and DL-PCBs in feed and food. The data from experimental animal and epidemiological studies were reviewed and it was decided to base the human risk assessment on effects observed in humans and to use animal data as supportive evidence. The critical effect was on semen quality, following pre- and postnatal exposure. The critical study showed a NOAEL of 7.0 pg WHO2005-TEQ/g fat in blood sampled at age 9 years based on PCDD/F-TEQs. No association was observed when including DL-PCB-TEQs. Using toxicokinetic modelling and taking into account the exposure from breastfeeding and a twofold higher intake during childhood, it was estimated that daily exposure in adolescents and adults should be below 0.25 pg TEQ/kg bw/day. The CONTAM Panel established a TWI of 2 pg TEQ/kg bw/week. With occurrence and consumption data from European countries, the mean and P95 intake of total TEQ by Adolescents, Adults, Elderly and Very Elderly varied between, respectively, 2.1 to 10.5, and 5.3 to 30.4 pg TEQ/kg bw/week, implying a considerable exceedance of the TWI. Toddlers and Other Children showed a higher exposure than older age groups, but this was accounted for when deriving the TWI. Exposure to PCDD/F-TEQ only was on average 2.4- and 2.7-fold lower for mean and P95 exposure than for total TEQ. PCDD/Fs and DL-PCBs are transferred to milk and eggs, and accumulate in fatty tissues and liver. Transfer rates and bioconcentration factors were identified for various species. The CONTAM Panel was not able to identify reference values in most farm and companion animals with the exception of NOAELs for mink, chicken and some fish species. The estimated exposure from feed for these species does not imply a risk.
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9
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Therapeutic Agents with AHR Inhibiting and NRF2 Activating Activity for Managing Chloracne. Antioxidants (Basel) 2018; 7:antiox7070090. [PMID: 30011787 PMCID: PMC6071176 DOI: 10.3390/antiox7070090] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 07/02/2018] [Accepted: 07/11/2018] [Indexed: 12/13/2022] Open
Abstract
Chloracne is the major skin symptom caused by dioxin intoxication. Dioxin activates the aryl hydrocarbon receptor (AHR)–cytochrome p450 1A1 (CYP1A1) system, generates oxidative stress, and induces hyperkeratinization of keratinocytes and sebocytes leading to chloracne. Nuclear factor-erythroid 2-related factor-2 (NRF2) is a master switch that induces the expression of various antioxidative enzymes, such as heme oxygenase-1. Cinnamaldehyde is an antioxidant phytochemical that inhibits AHR–CYP1A1 signaling and activates the NRF2–antioxidative axis. The cinnamaldehyde-containing Kampo herbal medicine Keishibukuryogan is capable of improving chloracne in Yusho patients who are highly contaminated with dioxin. Agents with dual functions in promoting AHR–CYP1A1 inhibition and NRF2 activation may be useful for managing dioxin-related health hazards.
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Pelcl T, Skrha J, Prazny M, Vlckova S, Fenclova Z, Navratil T, Malik J, Diblik P, Zikan V, Pelclova D. Diabetes, Cardiovascular Disorders and 2,3,7,8-Tetrachlorodibenzo-p-Dioxin Body Burden in Czech Patients 50 Years After the Intoxication. Basic Clin Pharmacol Toxicol 2018; 123:356-359. [DOI: 10.1111/bcpt.13013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 03/12/2018] [Indexed: 01/14/2023]
Affiliation(s)
- Tomas Pelcl
- 3rd Department of Internal Medicine; 1st Faculty of Medicine; Charles University in Prague and General University Hospital in Prague; Prague Czech Republic
| | - Jan Skrha
- 3rd Department of Internal Medicine; 1st Faculty of Medicine; Charles University in Prague and General University Hospital in Prague; Prague Czech Republic
| | - Martin Prazny
- 3rd Department of Internal Medicine; 1st Faculty of Medicine; Charles University in Prague and General University Hospital in Prague; Prague Czech Republic
| | - Stepanka Vlckova
- Department of Occupational Medicine; 1st Faculty of Medicine; Charles University in Prague and General University Hospital in Prague; Prague Czech Republic
| | - Zdenka Fenclova
- Department of Occupational Medicine; 1st Faculty of Medicine; Charles University in Prague and General University Hospital in Prague; Prague Czech Republic
| | - Tomas Navratil
- J. Heyrovsky Institute of Physical Chemistry of the CAS CR, v.v.i.; Prague Czech Republic
| | - Jan Malik
- 3rd Department of Internal Medicine; 1st Faculty of Medicine; Charles University in Prague and General University Hospital in Prague; Prague Czech Republic
| | - Pavel Diblik
- Department of Ophthalmology; 1st Faculty of Medicine; Charles University in Prague and General University Hospital in Prague; Prague Czech Republic
| | - Vit Zikan
- 3rd Department of Internal Medicine; 1st Faculty of Medicine; Charles University in Prague and General University Hospital in Prague; Prague Czech Republic
| | - Daniela Pelclova
- Department of Occupational Medicine; 1st Faculty of Medicine; Charles University in Prague and General University Hospital in Prague; Prague Czech Republic
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11
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Malisch R, Denison MS, Fiedler H, Fürst P, Hoogenboom RLAP, Schaechtele A, Schrenk D, van den Berg M. Do PCDD/PCDF standard solutions used in dioxin analysis pose a risk as potentially acutely toxic to lab personnel? CHEMOSPHERE 2017; 185:489-498. [PMID: 28715759 DOI: 10.1016/j.chemosphere.2017.07.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 07/03/2017] [Accepted: 07/05/2017] [Indexed: 06/07/2023]
Abstract
Laboratory safety requires protecting personnel from chemical exposures. Working with stock solutions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDFs) in routine analysis of feed and food with bioanalytical or physicochemical methods raises some concerns. Since PCDD/PCDFs are considered as possibly acutely toxic, the potential risks were evaluated to determine whether supervision of their use is necessary. Based on LD50-data for oral or dermal intake, hazard classification of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as a substance (category 1) and in commercially available TCDD standard solutions (category 4) is different. As worst case exposure scenario during routine laboratory work it was assumed that a dose of 100 ng TCDD gets onto the skin and is absorbed. This would result in the total body burden of a 70 kg person with 15 kg fat increasing from 10 (upper range of current background levels) to ∼17 pg of toxic equivalents (TEQs) of PCDD/PCDFs per g lipid, a level commonly observed over past decades. Chloracne, the main acute effect occurring weeks after exposure, is observed at much higher blood concentrations than estimated from accidental laboratory exposure. Immunotoxicity, developmental effects and other toxic effects may occur at lower blood levels, but require longer periods to develop. Since acute toxic symptoms don't occur within an "8 h acute time window", no supervision is necessary when working with standard solutions in routine analysis. Nevertheless, precautionary measures are needed regarding long-term adverse health effects and appropriate workplace conditions must exist to ensure that additional occupational exposure to PCDD/PCDFs by laboratory personnel is negligible.
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Affiliation(s)
- Rainer Malisch
- EU Reference Laboratory for Dioxins and PCBs in Feed and Food, Chemisches und Veterinäruntersuchungsamt, Bissierstr. 5, D-79114 Freiburg, Germany.
| | - Michael S Denison
- Department of Environmental Toxicology, University of California, Davis, CA 95616, USA
| | - Heidelore Fiedler
- Örebro University, School of Science and Technology, MTM Research Centre, SE-701 82 Örebro, Sweden
| | - Peter Fürst
- Chemisches und Veterinäruntersuchungsamt Münsterland-Emscher-Lippe (CVUA-MEL), Joseph-König-Straße 40, D-48147 Münster, Germany
| | | | - Alexander Schaechtele
- EU Reference Laboratory for Dioxins and PCBs in Feed and Food, Chemisches und Veterinäruntersuchungsamt, Bissierstr. 5, D-79114 Freiburg, Germany
| | - Dieter Schrenk
- Food Chemistry and Toxicology, University of Kaiserslautern, Erwin-Schrödinger-Straße 52, D-67663 Kaiserslautern, Germany
| | - Martin van den Berg
- Institute for Risk Assessment Sciences (IRAS), Utrecht University, Yalelaan 104, NL-3584 CM Utrecht, The Netherlands
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12
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Lee J, Prokopec SD, Watson JD, Sun RX, Pohjanvirta R, Boutros PC. Male and female mice show significant differences in hepatic transcriptomic response to 2,3,7,8-tetrachlorodibenzo-p-dioxin. BMC Genomics 2015; 16:625. [PMID: 26290441 PMCID: PMC4546048 DOI: 10.1186/s12864-015-1840-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 08/13/2015] [Indexed: 12/21/2022] Open
Abstract
Background 2,3,7,8–tetrachlorodibenzo-p-dixion (TCDD) is the most potent of the dioxin congeners, capable of causing a wide range of toxic effects across numerous animal models. Previous studies have demonstrated that males and females of the same species can display divergent sensitivity phenotypes to TCDD toxicities. Although it is now clear that most TCDD-induced toxic outcomes are mediated by the aryl hydrocarbon receptor (AHR), the mechanism of differential responses to TCDD exposure between sexes remains largely unknown. To investigate the differential sensitivities in male and female mice, we profiled the hepatic transcriptomic responses 4 days following exposure to various amounts of TCDD (125, 250, 500 or 1000 μg/kg) in adult male and female C57BL/6Kuo mice. Results Several key findings were revealed by our study. 1) Hepatic transcriptomes varied significantly between the sexes at all doses examined. 2) The liver transcriptome of males was more dysregulated by TCDD than that of females. 3) The alteration of “AHR-core” genes was consistent in magnitude, regardless of sex. 4) A subset of genes demonstrated sex-dependent TCDD-induced transcriptional changes, including Fmo3 and Nr1i3, which were significantly induced in livers of male mice only. In addition, a meta-analysis was performed to contrast transcriptomic profiles of various organisms and tissues following exposure to equitoxic doses of TCDD. Minimal overlap was observed in the differences between TCDD-sensitive or TCDD-resistant models. Conclusions Sex-dependent sensitivities to TCDD exposure are associated with a set of sex-specific TCDD-responsive genes. In addition, complex interactions between the aryl hydrocarbon and sex hormone receptors may affect the observable differences in sensitivity phenotypes between the sexes. Further work is necessary to better understand the roles of those genes altered by TCDD in a sex-dependent manner, and their association with changes to sex hormones and receptors. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1840-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jamie Lee
- Informatics and Bio-computing Program, Ontario Institute for Cancer Research, Toronto, Canada.
| | - Stephenie D Prokopec
- Informatics and Bio-computing Program, Ontario Institute for Cancer Research, Toronto, Canada.
| | - John D Watson
- Informatics and Bio-computing Program, Ontario Institute for Cancer Research, Toronto, Canada.
| | - Ren X Sun
- Informatics and Bio-computing Program, Ontario Institute for Cancer Research, Toronto, Canada. .,Department of Pharmacology & Toxicology, University of Toronto, Toronto, Canada.
| | - Raimo Pohjanvirta
- Department of Food Hygiene and Environmental Health, University of Helsinki, Helsinki, Finland. .,Laboratory of Toxicology, National Institute for Health and Welfare, Kuopio, Finland.
| | - Paul C Boutros
- Informatics and Bio-computing Program, Ontario Institute for Cancer Research, Toronto, Canada. .,Department of Pharmacology & Toxicology, University of Toronto, Toronto, Canada. .,Department of Medical Biophysics, University of Toronto, Toronto, Canada.
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13
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Patterson AT, Kaffenberger BH, Keller RA, Elston DM. Skin diseases associated with Agent Orange and other organochlorine exposures. J Am Acad Dermatol 2015. [PMID: 26210237 DOI: 10.1016/j.jaad.2015.05.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Organochlorine exposure is an important cause of cutaneous and systemic toxicity. Exposure has been associated with industrial accidents, intentional poisoning, and the use of defoliants, such as Agent Orange in the Vietnam War. Although long-term health effects are systematically reviewed by the Institute of Medicine, skin diseases are not comprehensively assessed. This represents an important practice gap as patients can present with cutaneous findings. This article provides a systematic review of the cutaneous manifestations of known mass organochlorine exposures in military and industrial settings with the goal of providing clinically useful recommendations for dermatologists seeing patients inquiring about organochlorine effects. Patients with a new diagnosis of chloracne, porphyria cutanea tarda, cutaneous lymphomas (non-Hodgkin lymphoma), and soft-tissue sarcomas including dermatofibrosarcoma protuberans and leiomyosarcomas should be screened for a history of Vietnam service or industrial exposure. Inconclusive evidence exists for an increased risk of other skin diseases in Vietnam veterans exposed to Agent Orange including benign fatty tumors, melanomas, nonmelanoma skin cancers, milia, eczema, dyschromias, disturbance of skin sensation, and rashes not otherwise specified. Affected veterans should be informed of the uncertain data in those cases. Referral to Department of Veterans Affairs for disability assessment is indicated for conditions with established associations.
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Affiliation(s)
- Andrew T Patterson
- Division of Dermatology, Ohio State University College of Medicine, Columbus, Ohio; US Air Force, San Antonio Military Medical Center
| | | | - Richard A Keller
- Dermatology, Audie L. Murphy Veterans Hospital, San Antonio, US Air Force, San Antonio, Texas
| | - Dirk M Elston
- Ackerman Academy of Dermatopathology; US Army (Retired)
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Becker RA, Patlewicz G, Simon TW, Rowlands JC, Budinsky RA. The adverse outcome pathway for rodent liver tumor promotion by sustained activation of the aryl hydrocarbon receptor. Regul Toxicol Pharmacol 2015; 73:172-90. [PMID: 26145830 DOI: 10.1016/j.yrtph.2015.06.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 06/19/2015] [Accepted: 06/22/2015] [Indexed: 12/29/2022]
Abstract
An Adverse Outcome Pathway (AOP) represents the existing knowledge of a biological pathway leading from initial molecular interactions of a toxicant and progressing through a series of key events (KEs), culminating with an apical adverse outcome (AO) that has to be of regulatory relevance. An AOP based on the mode of action (MOA) of rodent liver tumor promotion by dioxin-like compounds (DLCs) has been developed and the weight of evidence (WoE) of key event relationships (KERs) evaluated using evolved Bradford Hill considerations. Dioxins and DLCs are potent aryl hydrocarbon receptor (AHR) ligands that cause a range of species-specific adverse outcomes. The occurrence of KEs is necessary for inducing downstream biological responses and KEs may occur at the molecular, cellular, tissue and organ levels. The common convention is that an AOP begins with the toxicant interaction with a biological response element; for this AOP, this initial event is binding of a DLC ligand to the AHR. Data from mechanistic studies, lifetime bioassays and approximately thirty initiation-promotion studies have established dioxin and DLCs as rat liver tumor promoters. Such studies clearly show that sustained AHR activation, weeks or months in duration, is necessary to induce rodent liver tumor promotion--hence, sustained AHR activation is deemed the molecular initiating event (MIE). After this MIE, subsequent KEs are 1) changes in cellular growth homeostasis likely associated with expression changes in a number of genes and observed as development of hepatic foci and decreases in apoptosis within foci; 2) extensive liver toxicity observed as the constellation of effects called toxic hepatopathy; 3) cellular proliferation and hyperplasia in several hepatic cell types. This progression of KEs culminates in the AO, the development of hepatocellular adenomas and carcinomas and cholangiolar carcinomas. A rich data set provides both qualitative and quantitative knowledge of the progression of this AOP through KEs and the KERs. Thus, the WoE for this AOP is judged to be strong. Species-specific effects of dioxins and DLCs are well known--humans are less responsive than rodents and rodent species differ in sensitivity between strains. Consequently, application of this AOP to evaluate potential human health risks must take these differences into account.
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Affiliation(s)
- Richard A Becker
- Regulatory and Technical Affairs Department, American Chemistry Council (ACC), Washington, DC 20002, USA.
| | - Grace Patlewicz
- DuPont Haskell Global Centers for Health and Environmental Sciences, Newark, DE 19711, USA
| | - Ted W Simon
- Ted Simon LLC, 4184 Johnston Road, Winston, GA 30187, USA
| | - J Craig Rowlands
- The Dow Chemical Company, Toxicology & Environmental Research & Consulting, 1803 Building Washington Street, Midland, MI 48674, USA
| | - Robert A Budinsky
- The Dow Chemical Company, Toxicology & Environmental Research & Consulting, 1803 Building Washington Street, Midland, MI 48674, USA
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15
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Rosińczuk J, Całkosiński I. Effect of tocopherol and acetylsalicylic acid on the biochemical indices of blood in dioxin-exposed rats. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2015; 40:1-11. [PMID: 26056971 DOI: 10.1016/j.etap.2015.04.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 04/21/2015] [Accepted: 04/28/2015] [Indexed: 06/04/2023]
Abstract
New sources of dioxins and increased dioxin concentrations in the environment, coupled with their increased bioavailability along the food chain and accumulation in adipose tissues, contribute to various adverse long-term biological effects. The purpose of the study was to determine whether tocopherol protects the CNS by decreasing the pro-inflammatory influence of free radicals generated by TCDD; whether acetylsalicylic acid inhibits the production of inflammatory mediators; and whether the combined administration of tocopherol and acetylsalicylic acid to TCDD-exposed rats has a potential CNS-protective effect. The study included 117 rats divided into 8 groups: 75 female and 12 male Buffalo rats aged 8-10 weeks, weighing 140-160 g; as well as 30 female rats aged 6 weeks and weighing 120 g, which were the offspring of females from each study group. In the experiment, the following substances were used: 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), dosed at 5 μg/kg BW and 12.5 μg/kg BW, diluted in a 1% DMSO solution at the concentration of 1 μg/ml; α-tocopherol acetate, dosed at 30 mg/kg BW, in 0.2 ml of oil solution; and acetylsalicylic acid, 50mg/kg BW, suspended in 0.5 ml of starch solution, administered orally using a feeding tube. Pleurisy was induced by an injection of 0.15 ml of 1% carrageenin solution. The use of tocopherol reduces the adverse effects of the inflammatory reaction induced by TCDD. Administering tocopherol improves protein metabolism by reducing protein catabolism, and raises γ-globulin fraction levels. Combined acetylsalicylic acid and tocopherol suppress catabolic processes accompanying inflammation.
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Affiliation(s)
- Joanna Rosińczuk
- Department of Nervous System Diseases, The Faculty of Health Science, Wroclaw Medical University, Bartla 5 Street, 51-618 Wrocław, Poland.
| | - Ireneusz Całkosiński
- Department of Nervous System Diseases, The Faculty of Health Science, Wroclaw Medical University, Bartla 5 Street, 51-618 Wrocław, Poland.
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16
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Histopathological, ultrastructural, and immunohistochemical assessment of hippocampus structures of rats exposed to TCDD and high doses of tocopherol and acetylsalicylic acid. BIOMED RESEARCH INTERNATIONAL 2015; 2015:645603. [PMID: 25879034 PMCID: PMC4388018 DOI: 10.1155/2015/645603] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 03/13/2015] [Indexed: 12/21/2022]
Abstract
The effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on central nervous system consists of changing expression of estrogen receptors, whereas the result of chronic inflammatory reaction caused by dioxin is occurrence of destructive changes in various organs connected with disturbed metabolism of connective tissue and damage of cells. The aim of the study was to determine the effect of dioxins on function, ultrastructure, and cytological and histological structure of hippocampus, particularly on expression of estrogen receptors in central nervous system as well as to define protective influence of tocopherol (TCP) and acetylsalicylic acid (ASA) on the decrease in activity of proinflammatory effects in central nervous system. It was shown that TCDD contributes to destructive and inflammatory changes along with demyelization of myelin sheaths and atrophy of estrogen receptors in hippocampus. Dioxin contributes to atrophy of estrogen receptors in hippocampus, in which also destructive and inflammatory changes were found along with demyelination of myelin sheaths. Histopathological and ultrastructural image of hippocampus areas in rats, in which both TCP and ASA were used, is characterized by poorly expressed degenerative changes and smaller inflammatory reactivity. Using both TCP and ASA has a protective effect on functions of central nervous system.
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17
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Human urinary biomarkers of dioxin exposure: Analysis by metabolomics and biologically driven data dimensionality reduction. Toxicol Lett 2014; 230:234-43. [DOI: 10.1016/j.toxlet.2013.10.031] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 10/16/2013] [Accepted: 10/26/2013] [Indexed: 12/31/2022]
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18
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Role of AhR/ARNT system in skin homeostasis. Arch Dermatol Res 2014; 306:769-79. [PMID: 24966027 PMCID: PMC4220966 DOI: 10.1007/s00403-014-1481-7] [Citation(s) in RCA: 118] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 04/27/2014] [Accepted: 05/22/2014] [Indexed: 11/04/2022]
Abstract
Aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that binds to structurally diverse synthetic and naturally occurring chemicals including dioxins, flavonoids, tryptophan photoproducts, and Malassezia metabolites. Upon binding to its ligands, cytoplasmic AhR translocates to the nucleus, heterodimerizes with aryl hydrocarbon receptor nuclear translocator (ARNT), and mediates numerous biological and toxicological effects by inducing the transcription of various AhR-responsive genes. AhR ligation controls oxidation/antioxidation, epidermal barrier function, photo-induced response, melanogenesis, and innate immunity. This review summarizes recent advances in the understanding of the regulatory mechanisms of skin homeostasis mediated by the AhR/ARNT system.
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Schäfer M, Willrodt AH, Kurinna S, Link AS, Farwanah H, Geusau A, Gruber F, Sorg O, Huebner AJ, Roop DR, Sandhoff K, Saurat JH, Tschachler E, Schneider MR, Langbein L, Bloch W, Beer HD, Werner S. Activation of Nrf2 in keratinocytes causes chloracne (MADISH)-like skin disease in mice. EMBO Mol Med 2014; 6:442-57. [PMID: 24503019 PMCID: PMC3992072 DOI: 10.1002/emmm.201303281] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The transcription factor Nrf2 is a key regulator of the cellular stress response, and pharmacological Nrf2 activation is a promising strategy for skin protection and cancer prevention. We show here that prolonged Nrf2 activation in keratinocytes causes sebaceous gland enlargement and seborrhea in mice due to upregulation of the growth factor epigen, which we identified as a novel Nrf2 target. This was accompanied by thickening and hyperkeratosis of hair follicle infundibula. These abnormalities caused dilatation of infundibula, hair loss, and cyst development upon aging. Upregulation of epigen, secretory leukocyte peptidase inhibitor (Slpi), and small proline-rich protein 2d (Sprr2d) in hair follicles was identified as the likely cause of infundibular acanthosis, hyperkeratosis, and cyst formation. These alterations were highly reminiscent to the phenotype of chloracne/“metabolizing acquired dioxin-induced skin hamartomas” (MADISH) patients. Indeed, SLPI, SPRR2, and epigen were strongly expressed in cysts of MADISH patients and upregulated by dioxin in human keratinocytes in an NRF2-dependent manner. These results identify novel Nrf2 activities in the pilosebaceous unit and point to a role of NRF2 in MADISH pathogenesis.
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Affiliation(s)
- Matthias Schäfer
- Department of Biology, Institute of Molecular Health Sciences, ETH Zurich Zurich, Switzerland
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20
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Pereira SP, Pereira GC, Pereira CV, Carvalho FS, Cordeiro MH, Mota PC, Ramalho-Santos J, Moreno AJ, Oliveira PJ. Dioxin-induced acute cardiac mitochondrial oxidative damage and increased activity of ATP-sensitive potassium channels in Wistar rats. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2013; 180:281-290. [PMID: 23796802 DOI: 10.1016/j.envpol.2013.05.049] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 05/25/2013] [Accepted: 05/29/2013] [Indexed: 06/02/2023]
Abstract
The environmental dioxin 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is classified as a Group 1 human carcinogen and teratogenic agent. We hypothesize that TCDD-induced oxidative stress may also interfere with mitochondrial ATP-sensitive potassium channels (mitoKATP), which are known to regulate and to be regulated by mitochondrial redox state. We investigated the effects of an acute treatment of male Wistar rats with TCDD (50 μg/kg i.p.) and measured the regulation of cardiac mitoKATP. While the function of cardiac mitochondria was slightly depressed, mitoKATP activity was 52% higher in animals treated with TCDD. The same effects were not observed in liver mitochondria isolated from the same animals. Our data also shows that regulation of mitochondrial ROS production by mitoKATP activity is different in both groups. To our knowledge, this is the first report to show that TCDD increases mitoKATP activity in the heart, which may counteract the increased oxidative stress caused by the dioxin during acute exposure.
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Affiliation(s)
- Susana P Pereira
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal.
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21
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Całkosiński I, Rosińczuk-Tonderys J, Bazan J, Dzierzba K, Całkosińska M, Majda J, Dobrzyński M, Bronowicka-Szydełko A. The influence of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on hematological parameters during experimentally induced pleuritis in rats. Inflammation 2013; 36:387-404. [PMID: 23100032 PMCID: PMC3591537 DOI: 10.1007/s10753-012-9558-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Proper functioning of homeostatic mechanisms is characteristic for every healthy organism and enables adapting to environmental changes. These complicated systematic reactions can neutralize the harmful stress factors leading to various inflammatory reactions. The aim of this study was to determine dynamic changes in the inflammatory reaction after single 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) administration of 5 μg/kg body weight into rats with experimentally induced pleuritis. These changes were observed by monitoring the hematological blood parameters during inflammation. The obtained results proved that dioxins contribute to various changes in the character of the inflammatory response. TCDD administration before pleuritis initiation caused an increase of lymphocytes and significant decrease of the number of neutrophils during inflammation. The current study proved that administration of low TCDD dose (seven times lower than used in other studies) can cause thymus, spleen, or lymphatic gland atrophy. This finding indicates the toxic influence of small TCDD dose especially on the immune system.
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Affiliation(s)
- Ireneusz Całkosiński
- Department of Nervous System Diseases, The Faculty of Health Science, Wroclaw Medical University, Bartla 5, 51-618 Wroclaw, Poland
| | - Joanna Rosińczuk-Tonderys
- Department of Nervous System Diseases, The Faculty of Health Science, Wroclaw Medical University, Bartla 5, 51-618 Wroclaw, Poland
| | - Justyna Bazan
- Department of Nervous System Diseases, The Faculty of Health Science, Wroclaw Medical University, Bartla 5, 51-618 Wroclaw, Poland
| | - Katarzyna Dzierzba
- Department of Medical Biochemistry, Wroclaw Medical University, Chalubinskiego 10, 50-368 Wroclaw, Poland
| | - Monika Całkosińska
- Outpatient Clinic Medcom in Wojkowice, Wojkowice 28B, 55-020 Zurawina, Poland
| | - Jacek Majda
- Department of Diagnostics Laboratory, 4th Military Academic Hospital in Wroclaw, Weigla 5, 53-114 Wroclaw, Poland
| | - Maciej Dobrzyński
- Department of Conservative Dentistry and Pedodontics, Wroclaw Medical University, Krakowska 26, 50-425 Wroclaw, Poland
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22
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Vandenberg LN, Colborn T, Hayes TB, Heindel JJ, Jacobs DR, Lee DH, Shioda T, Soto AM, vom Saal FS, Welshons WV, Zoeller RT, Myers JP. Hormones and endocrine-disrupting chemicals: low-dose effects and nonmonotonic dose responses. Endocr Rev 2012; 33:378-455. [PMID: 22419778 PMCID: PMC3365860 DOI: 10.1210/er.2011-1050] [Citation(s) in RCA: 1953] [Impact Index Per Article: 162.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 02/07/2012] [Indexed: 02/08/2023]
Abstract
For decades, studies of endocrine-disrupting chemicals (EDCs) have challenged traditional concepts in toxicology, in particular the dogma of "the dose makes the poison," because EDCs can have effects at low doses that are not predicted by effects at higher doses. Here, we review two major concepts in EDC studies: low dose and nonmonotonicity. Low-dose effects were defined by the National Toxicology Program as those that occur in the range of human exposures or effects observed at doses below those used for traditional toxicological studies. We review the mechanistic data for low-dose effects and use a weight-of-evidence approach to analyze five examples from the EDC literature. Additionally, we explore nonmonotonic dose-response curves, defined as a nonlinear relationship between dose and effect where the slope of the curve changes sign somewhere within the range of doses examined. We provide a detailed discussion of the mechanisms responsible for generating these phenomena, plus hundreds of examples from the cell culture, animal, and epidemiology literature. We illustrate that nonmonotonic responses and low-dose effects are remarkably common in studies of natural hormones and EDCs. Whether low doses of EDCs influence certain human disorders is no longer conjecture, because epidemiological studies show that environmental exposures to EDCs are associated with human diseases and disabilities. We conclude that when nonmonotonic dose-response curves occur, the effects of low doses cannot be predicted by the effects observed at high doses. Thus, fundamental changes in chemical testing and safety determination are needed to protect human health.
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Affiliation(s)
- Laura N Vandenberg
- Tufts University, Center for Regenerative and Developmental Biology, Department of Biology, 200 Boston Avenue, Suite 4600, Medford, Massachusetts 02155, USA.
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23
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Rysavy NM, Maaetoft-Udsen K, Turner H. Dioxins: diagnostic and prognostic challenges arising from complex mechanisms. J Appl Toxicol 2012; 33:1-8. [PMID: 22610997 DOI: 10.1002/jat.2759] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 02/27/2012] [Accepted: 02/28/2012] [Indexed: 12/23/2022]
Abstract
Dioxins are ubiquitous environmental challenges to humans, with a pervasiveness that arises from 200 years of rapid industrialization and mechanization of Western societies and which is now extending into the developing world. In spite of their penetrance of the human biota, these compounds are poorly understood in terms of their true physiological potential for harm, and the mechanisms by which they impact cellular and organ level function are only recently becoming clear. Emerging awareness that chronic exposures to toxins may have generational and subtle effects on the outcomes of diseases such as cancer and diabetes, which are already multifactorial and highly complex, creates the context for the current review paper. Here, we summarize dioxin exposure paradigms and the resulting physiological effects that have been documented in animals and humans. Novel insights into potential endogenous end exogenous ligands, as well as the mechanisms by which these ligands impact acute and chronic cellular processes, are discussed. We develop the idea that the diagnosis of dioxin exposure, the subtleties of the cellular effects of the compounds and prognosis of the long-term effects of exposure are problems requiring that researchers leverage the power of genomics and epigenetics. However, the continuation of longitudinal epidemiological studies and the development of a firmer basis from which to extrapolate animal studies will be critical in ensuring optimal insight from these resource-intensive techniques.
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Affiliation(s)
- Noel M Rysavy
- Laboratory of Immunology and Signal Transduction, Chaminade University, Honolulu, HI 96822, USA
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25
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Black MB, Budinsky RA, Dombkowski A, Cukovic D, LeCluyse EL, Ferguson SS, Thomas RS, Rowlands JC. Cross-species comparisons of transcriptomic alterations in human and rat primary hepatocytes exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin. Toxicol Sci 2012; 127:199-215. [PMID: 22298810 DOI: 10.1093/toxsci/kfs069] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A toxicogenomics approach was used to qualitatively and quantitatively compare the gene expression changes in human and rat primary hepatocytes exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Hepatocytes from five individual rats and five individual humans were exposed for 24 h to 11 concentrations of TCDD ranging from 0.00001 to 100nM and a vehicle control. Gene expression changes were analyzed using whole-genome microarrays containing 13,002 orthologs. Significant changes in expression of individual orthologs at any concentration (fold change [FC] ± 1.5 and false discovery rate < 0.05) were higher in the rat (1547) compared with human hepatocytes (475). Only 158 differentially expressed orthologs were common between rats and humans. Enrichment analysis was performed on the differentially expressed orthologs in each species with 49 and 34 enriched human and rat pathways, respectively. Only 12 enriched pathways were shared between the two species. The results demonstrate significant cross-species differences in expression at both the gene and pathway level. Benchmark dose analysis of gene expression changes showed an average 18-fold cross-species difference in potency among differentially expressed orthologs with the rat more sensitive than the human. Similar cross-species differences in potency were observed for signaling pathways. Using the maximum FC in gene expression as a measure of efficacy, the human hepatocytes showed on average a 20% lower efficacy among the individual orthologs showing differential expression. The results provide evidence for divergent cross-species gene expression changes in response to TCDD and are consistent with epidemiological and clinical evidence showing humans to be less sensitive to TCDD-induced hepatotoxicity.
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Affiliation(s)
- Michael B Black
- The Hamner Institutes for Health Sciences, Research Triangle Park, North Carolina 27709, USA
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26
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Jennen D, Ruiz-Aracama A, Magkoufopoulou C, Peijnenburg A, Lommen A, van Delft J, Kleinjans J. Integrating transcriptomics and metabonomics to unravel modes-of-action of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in HepG2 cells. BMC SYSTEMS BIOLOGY 2011; 5:139. [PMID: 21880148 PMCID: PMC3231768 DOI: 10.1186/1752-0509-5-139] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 08/31/2011] [Indexed: 12/30/2022]
Abstract
BACKGROUND The integration of different 'omics' technologies has already been shown in several in vivo studies to offer a complementary insight into cellular responses to toxic challenges. Being interested in developing in vitro cellular models as alternative to animal-based toxicity assays, we hypothesize that combining transcriptomics and metabonomics data improves the understanding of molecular mechanisms underlying the effects caused by a toxic compound also in vitro in human cells. To test this hypothesis, and with the focus on non-genotoxic carcinogenesis as an endpoint of toxicity, in the present study, the human hepatocarcinoma cell line HepG2 was exposed to the well-known environmental carcinogen 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). RESULTS Transcriptomics as well as metabonomics analyses demonstrated changes in TCDD-exposed HepG2 in common metabolic processes, e.g. amino acid metabolism, of which some of the changes only being confirmed if both 'omics' were integrated. In particular, this integrated analysis identified unique pathway maps involved in receptor-mediated mechanisms, such as the G-protein coupled receptor protein (GPCR) signaling pathway maps, in which the significantly up-regulated gene son of sevenless 1 (SOS1) seems to play an important role. SOS1 is an activator of several members of the RAS superfamily, a group of small GTPases known for their role in carcinogenesis. CONCLUSIONS The results presented here were not only comparable with other in vitro studies but also with in vivo studies. Moreover, new insights on the molecular responses caused by TCDD exposure were gained by the cross-omics analysis.
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Affiliation(s)
- Danyel Jennen
- Department of Toxicogenomics, Maastricht University, PO Box 616, 6200 MD Maastricht, the Netherlands
- Netherlands Toxicogenomics Centre, PO Box 616, 6200 MD Maastricht, the Netherlands
| | - Ainhoa Ruiz-Aracama
- RIKILT-Institute of Food Safety, Wageningen University and Research Centre, PO Box 230, 6700 AE Wageningen, the Netherlands
- Netherlands Toxicogenomics Centre, PO Box 616, 6200 MD Maastricht, the Netherlands
| | - Christina Magkoufopoulou
- Department of Toxicogenomics, Maastricht University, PO Box 616, 6200 MD Maastricht, the Netherlands
| | - Ad Peijnenburg
- RIKILT-Institute of Food Safety, Wageningen University and Research Centre, PO Box 230, 6700 AE Wageningen, the Netherlands
- Netherlands Toxicogenomics Centre, PO Box 616, 6200 MD Maastricht, the Netherlands
| | - Arjen Lommen
- RIKILT-Institute of Food Safety, Wageningen University and Research Centre, PO Box 230, 6700 AE Wageningen, the Netherlands
- Netherlands Toxicogenomics Centre, PO Box 616, 6200 MD Maastricht, the Netherlands
| | - Joost van Delft
- Department of Toxicogenomics, Maastricht University, PO Box 616, 6200 MD Maastricht, the Netherlands
- Netherlands Toxicogenomics Centre, PO Box 616, 6200 MD Maastricht, the Netherlands
| | - Jos Kleinjans
- Department of Toxicogenomics, Maastricht University, PO Box 616, 6200 MD Maastricht, the Netherlands
- Netherlands Toxicogenomics Centre, PO Box 616, 6200 MD Maastricht, the Netherlands
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27
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Lensu S, Tuomisto JT, Tuomisto J, Pohjanvirta R. Characterization of the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-provoked strong and rapid aversion to unfamiliar foodstuffs in rats. Toxicology 2011; 283:140-50. [DOI: 10.1016/j.tox.2011.03.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 03/12/2011] [Indexed: 11/27/2022]
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Dioxins, the aryl hydrocarbon receptor and the central regulation of energy balance. Front Neuroendocrinol 2010; 31:452-78. [PMID: 20624415 DOI: 10.1016/j.yfrne.2010.07.002] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 06/15/2010] [Accepted: 07/05/2010] [Indexed: 01/03/2023]
Abstract
Dioxins are ubiquitous environmental contaminants that have attracted toxicological interest not only for the potential risk they pose to human health but also because of their unique mechanism of action. This mechanism involves a specific, phylogenetically old intracellular receptor (the aryl hydrocarbon receptor, AHR) which has recently proven to have an integral regulatory role in a number of physiological processes, but whose endogenous ligand is still elusive. A major acute impact of dioxins in laboratory animals is the wasting syndrome, which represents a puzzling and dramatic perturbation of the regulatory systems for energy balance. A single dose of the most potent dioxin, TCDD, can permanently readjust the defended body weight set-point level thus providing a potentially useful tool and model for physiological research. Recent evidence of response-selective modulation of AHR action by alternative ligands suggests further that even therapeutic implications might be possible in the future.
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Jablonska O, Shi Z, Valdez KE, Ting AY, Petroff BK. Temporal and anatomical sensitivities to the aryl hydrocarbon receptor agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin leading to premature acyclicity with age in rats. ACTA ACUST UNITED AC 2010; 33:405-12. [PMID: 20059580 DOI: 10.1111/j.1365-2605.2009.01031.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates diverse dioxin toxicities. While the acute effects of activation of the AhR pathway by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) have been a focus of past study, the role of this pathway in normal physiology and ageing is unclear. The purpose of this study was to identify the portion of the reproductive axis [ovary vs. hypothalamus and pituitary gland (H-H axis)] and the stages of the reproductive lifespan (foetal and early post-natal life vs. adolescence and adulthood) that are particularly sensitive to the effects of TCDD during female reproductive ageing. Adult pregnant Lewis rat dams were dosed with corn oil vehicle or TCDD (50 ng/kg-week by gavage) on days 14 and 21 of gestation and post-natal days 7 and 14 to provide in utero and lactational (IUL) exposure to pups. Female pups (n = 96) were weaned on post-natal day 21 and dosed with TCDD or vehicle weekly. Half of the pups were used as donors for ovary transplantation while the remainder were recipients. Following ovary transplantation, rats (n = 6-8 per group) received weekly TCDD or vehicle again until sacrifice at 8 months of age. Beginning at vaginal opening, reproductive cycles were monitored by vaginal cytology for 10 days each month. Blood samples were collected at 22.00 h on proestrus to measure concentration of 17beta-oestradiol in serum. Real-time PCR was used to determine differences in Cyp1a1, Cyp19a1, Cyp17a1, LH receptor (LHR), FoxA2 and FoxJ1 genes expression between control and remaining groups. IUL exposure of the H-H axis plus adult exposure of the whole body to TCDD significantly delayed puberty in females rats. Data analysis revealed an accelerated onset of acyclicity by 5 months in all groups involving IUL exposure of the developing ovary to TCDD. 17beta-oestradiol was significantly decreased in animals receiving TCDD during IUL exposure of the H-H axis. CYP1a1 expression was markedly greater in the liver than in ovarian tissue and correlated with ongoing TCDD exposure. Aromatase, 17alpha-hydroxylase and LHR gene expressions were largely unchanged (or occasionally elevated) by TCDD. FoxA2 and FoxJ1 mRNAs were similarly of limited value mechanistically, although FoxJ1 was much higher in TTT females (receiving TCDD as donor, recipient and adult). This study reveals a particular sensitivity of the developing ovary to TCDD leading to early loss of reproductive function with age.
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Affiliation(s)
- O Jablonska
- Department of Animal Physiology, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
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White SS, Birnbaum LS. An overview of the effects of dioxins and dioxin-like compounds on vertebrates, as documented in human and ecological epidemiology. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART C, ENVIRONMENTAL CARCINOGENESIS & ECOTOXICOLOGY REVIEWS 2009; 27:197-211. [PMID: 19953395 PMCID: PMC2788749 DOI: 10.1080/10590500903310047] [Citation(s) in RCA: 210] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Dioxins and dioxin-like compounds are primary examples of persistent organic pollutants that induce toxicity in both wildlife and humans. Over the past 200 years these compounds have been almost exclusively generated by human activity and have left a string of disasters in the wake of their accidental release. Most recently, the contamination of the Irish pork supply with dioxins resulted in an international recall of all Irish pork products. Epidemiologic data on human and ecological dioxin exposures have revealed a common pattern of biological response among vertebrate species, which is mediated through activation of the Aryl hydrocarbon Receptor (AhR). These AhR-mediated effects include profound consequences on the vertebrate individual exposed in early life with respect to myriad developmental endpoints including neurologic, immunologic, and reproductive parameters. Humans appear to be susceptible to these effects in a manner similar to that of the laboratory and wildlife species, which have demonstrated such outcomes. Furthermore, epidemiologic data suggest that there is little or no margin of exposure for humans with respect to these developmental effects. Given these concerns, prudent public health policy should include the continued reduction of exposures.
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Affiliation(s)
- Sally S. White
- National Center for Environmental Assessment, U.S. Environmental Protection Agency, Research Triangle Park, NC
| | - Linda S. Birnbaum
- Office of the Director, National Institute of Environmental Health Science, National Institutes of Health, Research Triangle Park, NC
- Corresponding Author: Linda S. Birnbaum, Ph.D., D.A.B.T., A.T.S., National Institute of Environmental Health Science, National Institutes of Health, Research Triangle Park, NC. Telephone: (919) 541- 3201.
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Guo SW, Simsa P, Kyama CM, Mihalyi A, Fulop V, Othman EER, D'Hooghe TM. Reassessing the evidence for the link between dioxin and endometriosis: from molecular biology to clinical epidemiology. Mol Hum Reprod 2009; 15:609-24. [DOI: 10.1093/molehr/gap075] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Bradshaw TD, Bell DR. Relevance of the aryl hydrocarbon receptor (AhR) for clinical toxicology. Clin Toxicol (Phila) 2009; 47:632-42. [PMID: 19640236 DOI: 10.1080/15563650903140423] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
INTRODUCTION The aryl hydrocarbon receptor (AhR) is a cellular signaling molecule infamous for mediating the toxicity of dioxins and related compounds. AIM The aim of this review is to provide a background of AhR and to examine critically its role in chemical toxicity, in physiological systems, and its interaction with drugs and other compounds. TOXICITY The AhR is essential for the toxicity of dioxins and related chemicals. The AhR mediates the exquisite sensitivity of animals to dioxins, where as little as 2 ng/kg/day can yield striking adverse effects. PHYSIOLOGICAL ROLE OF AHR: The wide variety of adverse effects of dioxin argues for an important role of the AhR in a variety of physiological systems. Recent investigations have highlighted the role of AhR in the development of the brain and vasculature. DRUGS AND OTHER CHEMICAL ACTIVATORS OF AHR: The development of AhR agonists during drug development programs is sometimes inadvertent, but sometimes the target of development, and is yet further confirmation of the likely importance of AhR signaling in constitutive physiology. The presence of AhR agonists in the diet such as indolo-(3,2-b)-carbazole and 3,3'-diindolylmethane (metabolized from indole 3-carbinol), flavonoids, and sulforaphane and of endogenous activators of this signaling system such as eicosanoids, indirubin, bilirubin, cAMP, and tryptophan are suggestive that AhR activation is a normal physiological process and that it is the persistent and high-level stimulation of AhR by dioxins that is responsible for toxicity. CONCLUSIONS AhR-mediated toxicity and physiology are highly relevant to clinical toxicology and drug development.
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Valdez KE, Shi Z, Ting AY, Petroff BK. Effect of chronic exposure to the aryl hydrocarbon receptor agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin in female rats on ovarian gene expression. Reprod Toxicol 2009; 28:32-7. [PMID: 19490992 DOI: 10.1016/j.reprotox.2009.03.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 01/22/2009] [Accepted: 03/14/2009] [Indexed: 01/24/2023]
Abstract
The aryl hydrocarbon receptor (AHR) mediates the effects of many endocrine disruptors and contributes to the loss of fertility in polluted environments. Female rats exposed chronically to environmentally relevant doses of the AHR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) across their lifespan experience accelerated reproductive senescence preceded by ovarian endocrine disruption. The purpose of this study was to determine the changes in ovarian gene expression that accompany the loss of ovarian function caused by chronic exposure to TCDD. Beginning in utero, female Sprague-Dawley rats received TCDD (1, 5, 50, or 200 ng/kg-week; n=4 per group) or vehicle weekly throughout their lifespan, and were sacrificed on diestrus just prior to loss of reproductive cyclicity at 11 months of age. Microarray analysis was used to determine differences in ovarian gene expression between control and TCDD-treated (200 ng/kg-week) animals. To confirm microarray results, real-time PCR was used to assess changes in gene expression among treatment groups. TCDD treatment decreased (p<0.05) proestrus serum estradiol concentrations with no effect on serum progesterone. In ovaries from rats treated with 200 ng/kg-week TCDD compared to controls, 19 genes of known function were found to be up-regulated, while 31 ovarian genes were found to be down-regulated >or=1.5-fold (p<or=0.05). Gene expression of 17 alpha-hydroxylase decreased following chronic TCDD treatment, suggesting the decrease in estradiol biosynthesis may be a consequence of decreased substrate. Taken together with past studies indicating a lack of effect on hypothalamus or pituitary function, the apparent regulation of key ovarian genes support the hypothesis that chronic TCDD exposure directly affects ovarian function.
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Affiliation(s)
- Kelli E Valdez
- Center for Reproductive Sciences, Department of Internal Medicine, University of Kansas Medical Center, Kansas City, KS 66160, USA
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Ray S, Swanson H. Activation of the aryl hydrocarbon receptor by TCDD inhibits senescence: a tumor promoting event? Biochem Pharmacol 2009; 77:681-8. [PMID: 19100242 PMCID: PMC2662439 DOI: 10.1016/j.bcp.2008.11.022] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 11/12/2008] [Accepted: 11/21/2008] [Indexed: 01/03/2023]
Abstract
Activation of the aryl hydrocarbon receptor (AHR) by the agonist, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been shown to promote tumor formation in both liver and skin. In the liver, but not the skin, the AHR-mediated events that contribute to TCDD's tumor promoting activities have been studied in some detail and are thought to involve perturbation of cell fate processes. However, studies performed using cultured cells have often resulted in apparent contradictory results indicating that the impact of TCDD on cell fate processes may be cell context dependent. We and others have shown that in primary cultured keratinocytes TCDD increases post-confluent proliferation and increases late differentiation. Further, our studies performed in these cells indicate that TCDD can also inhibit culture-induced senescence. While senescence, a permanent cell cycle arrest, is emerging as an important process regulated by oncogenes and considered to be of therapeutic importance, its role with respect to TCDD/AHR mediated tumor promotion has not been fully considered. The intent of this article is to focus primarily on senescence as a cell process relevant to skin tumorigenesis and explore the idea that the inhibition of senescence by TCDD could be an important mechanism by which it may exert its tumor promoting effects in the skin.
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Affiliation(s)
- S. Ray
- Biogen, Inc. Cambridge, MA 02142
| | - H.I. Swanson
- Department of Molecular and Biomedical Pharmacology, University of Kentucky College of Medicine, Lexington, KY 40536
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35
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Abstracts of the European Association of Poisons Centres and Clinical Toxicologists XXV International Congress. Clin Toxicol (Phila) 2008. [DOI: 10.1080/07313820500207624] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Yoshizawa K, Heatherly A, Malarkey DE, Walker NJ, Nyska A. A critical comparison of murine pathology and epidemiological data of TCDD, PCB126, and PeCDF. Toxicol Pathol 2007; 35:865-79. [PMID: 18098033 PMCID: PMC2623249 DOI: 10.1080/01926230701618516] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, or dioxin) and dioxin-like compounds (DLCs) induce numerous toxicities, including developmental, endocrine, immunological, and multi-organ carcinogenic, in animals and/or humans. Multiple studies completed by the National Toxicology Program (NTP) focused on the effects caused in Harlan Sprague-Dawley rats by specific DLCs, among them the prototypical dioxin, TCDD. Because humans are exposed daily to a combination of DLCs, primarily via ingestion of food, the Toxic Equivalency Factor (TEF) was developed in order to evaluate health hazards caused by these mixtures. Herein we review the pathological effects reported in humans exposed to TCDD; 3,3',4,4',5-pentachlorobiphenyl (PCB 126); and 2,3,4,7,8,-pentachlorodibenzofuran (PeCDF) and compare them to similar changes seen in NTP murine studies performed with the same compounds. While there were differences in specific pathologies observed, clear consistency in the target organs affected (liver, oral cavity, cardiovascular system, immune system, thyroid, pancreas, and lung) could be seen in both human studies and rodent toxicity and carcinogenicity investigations.
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Affiliation(s)
- Katsuhiko Yoshizawa
- Toxicologic Pathology, Drug Safety Research Laboratories, Astellas Pharma Inc., Yodogawa, Osaka, Japan
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37
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Simsa P, Járási ZE, Fülöp V. [Environmental dioxin compounds as the cause of endometriosis and other diseases]. Orv Hetil 2007; 148:1745-50. [PMID: 17827083 DOI: 10.1556/oh.2007.28172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
There has been much debate of late about whether or not dioxin, an industrial toxin, could be a causative agent in the onset of endometriosis, a gynaecological disease associated with infertility and pain. Studies found either no difference in serum dioxin concentrations when cases were compared to controls or a non-significant increase, or reached low statistical power. The introductory results on Rhesus monkey contradict with the observations on mice fed with dioxin and oestrogen simultaneously. Genetic comparison shows that human belongs to the dioxin resistant races so dioxin concentrations measured in the population could not cause disease especially not an oestrogen dependent one, like endometriosis.
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Affiliation(s)
- Péter Simsa
- Országos Gyógyintézeti Központ, Nogyógyászati Osztály, Budapest.
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38
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Warner M, Eskenazi B, Olive DL, Samuels S, Quick-Miles S, Vercellini P, Gerthoux PM, Needham L, Patterson DG, Mocarelli P. Serum dioxin concentrations and quality of ovarian function in women of Seveso. ENVIRONMENTAL HEALTH PERSPECTIVES 2007; 115:336-40. [PMID: 17431480 PMCID: PMC1849930 DOI: 10.1289/ehp.9667] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Accepted: 12/20/2006] [Indexed: 05/09/2023]
Abstract
BACKGROUND Although 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been associated with alterations in ovarian function and hormones in animals, it has not been studied in humans. On 10 July 1976, an explosion exposed residents of Seveso, Italy, to the highest levels of TCDD in a population. Twenty years later, we initiated the Seveso Women's Health Study to study reproductive health. OBJECTIVE We related TCDD levels measured in sera collected near the time of explosion and ovarian function (ovarian cysts, ovarian follicles, ovulation rate, serum hormones) at follow-up. METHODS We included 363 women who were 20-40 years of age and nonusers of oral contraceptives. We examined the relationship of 1976 serum TCDD levels with ultrasound-detected ovarian follicles among 96 women in the menstrual follicular phase and serum hormone levels (estradiol, progesterone) among 129 women in the menstrual luteal phase at follow-up. Ovulation was defined by serum progesterone levels > 3 ng/mL. RESULTS The median serum TCDD level was 77.3 ppt, lipid-adjusted. Serum TCDD was not associated with number or size of ovarian follicles. Of women in the luteal phase, 87 (67%) ovulated. Serum log(10)TCDD was not associated with odds of ovulation [adjusted odds ratio = 0.99; 95% confidence interval (CI), 0.5 to 1.9]. Among those who had ovulated, serum log(10)TCDD was not associated with serum progesterone [adjusted beta (adj-beta ) = -0.70; 95% CI, -2.4 to 1.0] or estradiol (adj-beta = -1.81; 95% CI, -10.4 to 6.8). CONCLUSIONS We found no clear evidence that 1976 TCDD exposure was associated with ovarian function 20 years later in women exposed to relatively high levels in Seveso, Italy.
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Affiliation(s)
- Marcella Warner
- School of Public Health, University of California at Berkeley, Berkeley, California 94720-7360, USA.
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Shi Z, Valdez KE, Ting AY, Franczak A, Gum SL, Petroff BK. Ovarian Endocrine Disruption Underlies Premature Reproductive Senescence Following Environmentally Relevant Chronic Exposure to the Aryl Hydrocarbon Receptor Agonist 2,3,7,8-Tetrachlorodibenzo-p-Dioxin1. Biol Reprod 2007; 76:198-202. [PMID: 17050859 DOI: 10.1095/biolreprod.106.053991] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The aryl hydrocarbon receptor (AHR) mediates the effects of many endocrine disruptors and contributes to the loss of fertility in polluted environments. While previous work has focused on mechanisms of short-term endocrine disruption and ovotoxicity in response to AHR ligands, we have shown recently that chronic exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces premature reproductive senescence in female rats without depletion of ovarian follicular reserves. In the current study, premature reproductive senescence was induced using a range of low-dose exposure to TCDD (0, 1, 5, 50, and 200 ng kg(-1) wk(-1)) beginning in utero and continuing until the transition to reproductive senescence. Doses of 50 and 200 ng TCDD kg(-1) wk(-1) delayed the age at vaginal opening and accelerated the loss of normal reproductive cyclicity with age without depletion of follicular reserves. Serum estradiol concentrations were decreased in a dose-dependent fashion (> or = 5 ng kg(-1) wk(-1)) across the estrous cycle in perisenescent rats still displaying normal cyclic vaginal cytology. Serum FSH, LH, and progesterone profiles were unchanged by TCDD. The loss of reproductive cyclicity following chronic exposure to TCDD was not accompanied by decreased responsiveness to GnRH. Ovarian endocrine disruption is the predominant functional change preceding the premature reproductive senescence induced by chronic exposure to low doses of the AHR-specific ligand TCDD.
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Affiliation(s)
- Zhanquan Shi
- Center for Reproductive Sciences, Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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Biasioli M, Ajmone-Marsan F. Organic and inorganic diffuse contamination in urban soils: the case of Torino (Italy). ACTA ACUST UNITED AC 2007; 9:862-8. [PMID: 17671668 DOI: 10.1039/b705285e] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Soils in urban parks are useful tracers of diffuse contamination and could represent a potential health risk for citizens. Soils in the parks of Torino, Italy, were sampled and analysed for a broad range of organic and inorganic contaminants. Concentrations of potentially toxic elements, PAHs, PCBs and polychlorinated dibenzo-p-dioxins and dibenzofurans were often above national legislation limits, and higher than surrounding rural areas or than other cities. Mean concentrations were 233 mg kg(-1) for Cr, 164 mg kg(-1) for Ni, 124 mg kg(-1) for Pb and 170 mg kg(-1) for Zn. Other inorganic contaminants such as Cd, As, and Hg showed high concentrations in some soils. Organic contaminants were also found to be enriched in the sampled parks (e.g. maximum concentrations of PCDDs/DFs and PCBs were 12.6 ng kg(-1) and 0.310 mg kg(-1), respectively). Data from this study reveal an important enrichment of parks for some contaminants, reflecting the intensity of phenomena of diffuse contamination. Historical parks presented the highest degree of contamination, suggesting that the age of soils rather than their proximity to sources of emissions is a key factor in determining soil contamination. Data obtained in this study could be of help in the investigation and remediation practices of urban contaminated sites within large cities.
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Affiliation(s)
- Mattia Biasioli
- DI.VA.P.R.A., Chimica Agraria, Università di Torino, Via Leonardo da Vinci, 44, 10095 Grugliasco, Torino, Italy.
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Panteleyev AA, Bickers DR. Dioxin-induced chloracne--reconstructing the cellular and molecular mechanisms of a classic environmental disease. Exp Dermatol 2006; 15:705-30. [PMID: 16881967 DOI: 10.1111/j.1600-0625.2006.00476.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is among the most toxic pollutants known to date that serves as a prototype for a group of halogenated hydrocarbon compounds characterized by extraordinary environmental persistence and unique ability to concentrate in animal and human tissues. TCDD can elicit a complex array of pleiotropic adverse effects in humans, although chloracne, a specific type of acne-like skin disease, is the only consistent manifestation of dioxin intoxication, thus representing a 'hallmark' of TCDD exposure. Chloracne is considered to be one of the most specific and sensitive biomarkers of TCDD intoxication that allows clinical and epidemiological evaluation of exposure level at threshold doses. The specific cellular and molecular mechanisms involved in pathogenesis of chloracne are still unknown. In this review, we summarize the available clinical data on chloracne and recent progress in understanding the role of the dioxin-dependent pathway in the control of gene transcription and discuss molecular and cellular events potentially involved in chloracne pathogenesis. We propose that the dioxin-induced activation of skin stem cells and a shift in differentiation commitment of their progeny may represent a major mechanism of chloracne development.
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Reiner EJ, Clement RE, Okey AB, Marvin CH. Advances in analytical techniques for polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and dioxin-like PCBs. Anal Bioanal Chem 2006; 386:791-806. [PMID: 16794816 PMCID: PMC1764597 DOI: 10.1007/s00216-006-0479-1] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Revised: 04/04/2006] [Accepted: 04/10/2006] [Indexed: 11/25/2022]
Abstract
Analytical techniques for the determination of polychorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF) and dioxin-like PCBs (DLPCB) are reviewed. The focus of the review is on recent advances in methodology and analytical procedures. The paper also reviews toxicology, the development of toxic equivalent factors (TEF) and the determination of toxic equivalent quantity (TEQ) values. Sources, occurrence and temporal trends of PCDD/PCDF are summarized to provide examples of levels and concentration ranges for the methods and techniques reviewed.
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Affiliation(s)
- Eric J Reiner
- Ontario Ministry of the Environment, Toronto, ON, Canada.
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Schecter A, Birnbaum L, Ryan JJ, Constable JD. Dioxins: an overview. ENVIRONMENTAL RESEARCH 2006; 101:419-28. [PMID: 16445906 DOI: 10.1016/j.envres.2005.12.003] [Citation(s) in RCA: 306] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Revised: 11/22/2005] [Accepted: 12/05/2005] [Indexed: 05/04/2023]
Abstract
This review article summarizes what is known about human health following exposure to dioxins. It is meant primarily for health professionals but was also written with the general public in mind. The need for such an article became apparent to the authors following media inquiries at the time the then Ukraine presidential candidate Victor Yushchenko was deliberately poisoned with the most toxic dioxin, tetrachlorodibenzodioxin or TCDD.
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Affiliation(s)
- Arnold Schecter
- University of Texas Health Science Center, School of Public Health, Dallas Campus, Dallas, TX 75390, USA.
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Schuhmacher M, Jones KC, Domingo JL. Air-vegetation transfer of PCDD/PCDFs: an assessment of field data and implications for modeling. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2006; 142:143-50. [PMID: 16298466 DOI: 10.1016/j.envpol.2005.09.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2005] [Accepted: 09/14/2005] [Indexed: 05/05/2023]
Abstract
This study was designed to evaluate soil and air (gas and particle) transfer of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) to vegetation in residential and industrial areas. In a first part, soil-vegetation transfer was assessed. The levels of PCDD/Fs in 120 soil and 120 herbage samples collected from 1996 to 2002 in an industrial area of Montcada (Barcelona, Spain), near a municipal solid waste incinerator (MSWI), were determined. Some additional individual samples were also evaluated. It was concluded that high soil concentrations, which are not at steady state with the air layer above it, show a tendency for PCDD/Fs to escape via volatilization. In a second part of the study, air-vegetation transfer was examined. PCDD/F concentrations from 24 herbage samples were used, while PCDD/F concentrations were also measured in seven high-volume air samples and seven passive air-vapor samples. Scavenging coefficients (m3 air "sampled"/g grass d.m.) ranged from 1.9 to 11.3 m3/g. A good trend with K(OA) was observed for PCDDs (R=0.82), while it was lower for PCDFs (R=0.55). The current results corroborate that PCDD/F concentrations in vegetation are associated with atmospheric deposition. For the highest substituted PCDD/F congeners, the air-particle uptake from plants is the principal pathway. In regions impacted by combustion emission sources, PCDD/F gas-particle partitioning is influenced by a higher concentration of particles in the air. Particles and associated particle-bound PCDD/Fs would sorb to leaf surfaces, and are subject to removal via wash off. However, in areas where emissions to air are not very notable, vapor absorption would be the principal source of vegetation pollution. The results of this investigation can have a potential interest in risk assessment studies and environmental fate models.
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Affiliation(s)
- Marta Schuhmacher
- Laboratory of Toxicology and Environmental Health, School of Medicine, Rovira i Virgili University, San Lorenzo 21, 43201 Reus, Spain
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Rifkind AB. CYP1A in TCDD toxicity and in physiology-with particular reference to CYP dependent arachidonic acid metabolism and other endogenous substrates. Drug Metab Rev 2006; 38:291-335. [PMID: 16684662 DOI: 10.1080/03602530600570107] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Toxicologic and physiologic roles of CYP1A enzyme induction, the major biochemical effect of aryl hydrocarbon receptor activation by TCDD and other receptor ligands, are unknown. Evidence is presented that CYP1A exerts biologic effects via metabolism of endogenous substrates (i.e., arachidonic acid, other eicosanoids, estrogens, bilirubin, and melatonin), production of reactive oxygen, and effects on K(+) and Ca(2+) channels. These interrelated pathways may connect CYP1A induction to TCDD toxicities, including cardiotoxicity, vascular dysfunction, and wasting. They may also underlie homeostatic roles for CYP1A, especially when transiently induced by common chemical exposures and environmental conditions (i.e., tryptophan photoproducts, dietary indoles, and changes in oxygen tension).
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Affiliation(s)
- Arleen B Rifkind
- Department of Pharmacology, Weill Medical College of Cornell University, New York, NY 10021, USA.
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Tuomisto J, Pekkanen J, Kiviranta H, Tukiainen E, Vartiainen T, Viluksela M, Tuomisto JT. Dioxin cancer risk--example of hormesis? Dose Response 2006; 3:332-41. [PMID: 18648613 DOI: 10.2203/dose-response.003.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
A recent case-control study implied an inverse correlation between the measured body burden of dioxins (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, PCDD/F) and the risk of soft tissue sarcoma in normal population exposed to dioxins mainly via food. The surprising result could not be explained by biases or confounding. There is no a priori confounding by occupational chemicals in a random sample from general population, but exposures to other lipid soluble chemicals with similar sources might be expected to associate with that of dioxins. One such group is polychlorinated biphenyls (PCB). Therefore three most relevant dioxin-like PCB compounds PCB 77, PCB 126, and PCB 169 were now analyzed from the same patients. Cases were 110 soft-tissue sarcoma patients undergoing surgery for their disease, and referents were 227 patients operated for appendicitis. Dioxin and PCB concentrations were analyzed from subcutaneous fat samples by high-resolution gas chromatography-mass spectrometry and TCDD equivalent concentrations (WHO-TEq) were calculated by using toxicity equivalency factors of WHO. The highest risk of sarcoma was found in the septile with the lowest body burden of sum WHO-TEq, and the differences of septiles 2 and 6 from septile 1 were statistically significant. If soft sarcoma risk is true at high occupational levels of dioxins, the provocative result suggests that a possibility of a J-shaped dose-response curve should be taken into consideration and studied further. This is also supported by the similar J-shaped dose responses in animal studies.
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Affiliation(s)
- Jouko Tuomisto
- Department of Environmental Health, National Public Health Institute, Kuopio, Finland.
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Pelclová D, Urban P, Preiss J, Lukás E, Fenclová Z, Navrátil T, Dubská Z, Senholdová Z. Adverse health effects in humans exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). REVIEWS ON ENVIRONMENTAL HEALTH 2006; 21:119-38. [PMID: 16898675 DOI: 10.1515/reveh.2006.21.2.119] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The environmental contaminant 2,3,7,8-tetrachlordibenzo-p-dioxin (TCDD) belongs to the category of highly toxic, persistent organic pollutants that accumulate in animal fat and plant tissues. Today, background TCDD levels in human fat are showing a decreasing trend. The food chain is the main source of exposure in the human population. TCDD regulates the expression of a wide range of drug-metabolizing enzymes and has an impact on a large number of biological systems. The most pronounced effects have occurred in occupational settings following the uncontrolled formation of TCDD after industrial accidents, as well as in rare intentional intoxications. Although the acute effects of TCDD exposure are well described in the literature, the long-term consequences have been underevaluated. The most well-known symptoms of severe acute intoxication are chloracne, porphyria, transient hepatotoxicity, and peripheral and central neurotoxicity. Because of the long-term persistence of TCDD in the human body, atherosclerosis, hypertension, diabetes, vascular ocular changes, and signs of neural system damage, including neuropsychological impairment, can be present several decades after massive exposure. Such chronic effects are nonspecific, multifactorial, and may be causally linked to TCDD only in heavily intoxicated subjects. This opinion is supported by the dose-dependent effect of TCDD found in exposed workers and by experimental animal studies.
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Affiliation(s)
- Daniela Pelclová
- Department of Occupational Medicine, Ist Medical Faculty, Charles University and General Faculty Hospital, Prague, Czech Republic.
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Connor KT, Aylward LL. Human response to dioxin: aryl hydrocarbon receptor (AhR) molecular structure, function, and dose-response data for enzyme induction indicate an impaired human AhR. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2006; 9:147-71. [PMID: 16613807 DOI: 10.1080/15287390500196487] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The aryl hydrocarbon receptor (AhR) mediates nearly all studied adverse effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and many related compounds. Binding of TCDD or related ligands to AhR is the key initiating event in downstream biochemical responses. The binding affinity of AhR for TCDD is specific to species and strain, and studies of human AhR demonstrate binding affinities approximately an order of magnitude or more lower than those observed in the most sensitive laboratory strains and species. Molecular genetic studies confirmed that human AhR shares key mutations with the DBA mouse strain that result in an "impaired" AhR (with respect to TCDD binding and responsiveness). Despite a number of polymorphisms in human AhR, the key "DBA-type" mutations appear to be a constant feature of the human AhR, and no polymorphisms have been identified that compensate for the impaired binding function conferred by these mutations. Consistent with the impaired binding status of the human AhR, human cells have consistently required approximately 10-fold higher concentrations of TCDD in vitro than rodent cells to respond with enzyme induction. Recent studies of in vivo enzyme induction-related endpoints in human populations with moderately and highly increased TCDD body burdens detected no relationship between these endpoints and TCDD body burdens at body-burden levels up to 250 ng TEQ/kg body weight, or approximately 25 times above the upper range of current general population background body burdens, while marked elevations in enzyme activity were observed in persons with body burdens above 750 ng TEQ/kg. In contrast, the more sensitive laboratory rodent strains and species exposed to TCDD exhibit significant enzyme induction at body burdens below 50 ng/kg. These interspecies data on the most sensitive and best understood response to binding of TCDD and related compounds to the AhR are consistent with the binding affinity and molecular structure data and support the hypothesis that the human AhR is less functional than the AhR of the more sensitive laboratory animals at a molecular level. Quantitative risk assessments involving interspecies extrapolation from sensitive laboratory species and strains should take these fundamental differences into account when margins of exposure and safety factors are considered.
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Franczak A, Nynca A, Valdez KE, Mizinga KM, Petroff BK. Effects of Acute and Chronic Exposure to the Aryl Hydrocarbon Receptor Agonist 2,3,7,8-Tetrachlorodibenzo-p-Dioxin on the Transition to Reproductive Senescence in Female Sprague-Dawley Rats1. Biol Reprod 2006; 74:125-30. [PMID: 16177221 DOI: 10.1095/biolreprod.105.044396] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Activation of the aryl hydrocarbon receptor (AHR) can occur in polluted environments, either from smoking-related toxicants or from endogenous ligands. We tested whether acute or chronic exposure to the AHR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) alters the transition to reproductive senescence in female Sprague-Dawley rats. In experiment 1, rats (n = 6 per experimental group) received a single dose of 0 or 10 mug/kg of TCDD orally (p.o.) on Postnatal Day 29. Vaginal cytology was monitored for 1 wk each month until rats were killed at 1 yr of age. The single prepubertal exposure to TCDD hastened the transition to reproductive senescence in female rats and was associated with delayed puberty, abnormal cyclicity, and premature reproductive senescence. In a second experiment, rats were exposed to TCDD chronically through weekly dosing (0, 50, or 200 ng kg(-1) wk(-1) p.o., n = 7 each dose) beginning in utero. Lifelong exposure to these lower doses of TCDD induced a dose- and time-dependent loss of normal cyclicity and significantly hastened the onset of the transition to reproductive senescence (P < 0.05). This premature transition to reproductive senescence was associated with prolonged estrous cycles and, at the highest dose of TCDD, persistent estrus or diestrus. The number and size of ovarian follicles were not altered by TCDD. Diestrous concentrations of LH in rats exposed chronically to TCDD were similar to those in controls, whereas progesterone tended to be elevated at both doses of the dioxin (P < 0.08). Serum FSH was elevated in the group exposed to 50 ng/kg of TCDD (P < 0.02), whereas estradiol was decreased at both doses of dioxin (P < 0.01). Data thus far support endocrine disruption rather than depletion of follicular reserves as a primary mechanism of the premature transition to reproductive senescence following activation of the AHR pathway by TCDD in female rats.
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Affiliation(s)
- Anita Franczak
- Center for Reproductive Sciences, Department of Internal Medicine, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
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Eskenazi B, Warner M, Marks AR, Samuels S, Gerthoux PM, Vercellini P, Olive DL, Needham L, Patterson D, Mocarelli P. Serum dioxin concentrations and age at menopause. ENVIRONMENTAL HEALTH PERSPECTIVES 2005; 113:858-62. [PMID: 16002373 PMCID: PMC1257646 DOI: 10.1289/ehp.7820] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2004] [Accepted: 03/24/2005] [Indexed: 05/03/2023]
Abstract
2,3,7,8-Tetrachlorobenzo-p-dioxin (TCDD), a halogenated compound that binds the aryl hydrocarbon receptor, is a by-product of numerous industrial processes including waste incineration. Studies in rats and monkeys suggest that TCDD may affect ovarian function. We examined the relationship of TCDD and age at menopause in a population of women residing near Seveso, Italy, in 1976, at the time of a chemical plant explosion. We included 616 of the women who participated 20 years later in the Seveso Women's Health Study. All women were premenopausal at the time of the explosion, had TCDD levels measured in serum collected soon after the explosion, and were > or = 35 years of age at interview. Using proportional hazards modeling, we found a 6% nonsignificant increase in risk of early menopause with a 10-fold increase in serum TCDD. When TCDD levels were categorized, compared with women in the lowest quintile (< 20.4 ppt), women in quintile 2 (20.4-34.2 ppt) had a hazard ratio (HR) of 1.1 (p = 0.77), quintile 3 (34.3-54.1 ppt) had an HR of 1.4 (p = 0.14), quintile 4 (54.2-118 ppt) had an HR of 1.6 (p = 0.10), and quintile 5 (> 118 ppt) had an HR of 1.1 (p = 0.82) for risk of earlier menopause. The trend toward earlier menopause across the first four quintiles is statistically significant (p = 0.04). These results suggest a nonmonotonic dose-related association with increasing risk of earlier menopause up to about 100 ppt TCDD, but not above.
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Affiliation(s)
- Brenda Eskenazi
- School of Public Health, University of California at Berkeley, Berkeley, California 94720-7360, USA.
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