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Rakateli L, Huchzermeier R, van der Vorst EPC. AhR, PXR and CAR: From Xenobiotic Receptors to Metabolic Sensors. Cells 2023; 12:2752. [PMID: 38067179 PMCID: PMC10705969 DOI: 10.3390/cells12232752] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 11/23/2023] [Accepted: 11/30/2023] [Indexed: 12/18/2023] Open
Abstract
Traditionally, xenobiotic receptors are known for their role in chemical sensing and detoxification, as receptor activation regulates the expression of various key enzymes and receptors. However, recent studies have highlighted that xenobiotic receptors also play a key role in the regulation of lipid metabolism and therefore function also as metabolic sensors. Since dyslipidemia is a major risk factor for various cardiometabolic diseases, like atherosclerosis and non-alcoholic fatty liver disease, it is of major importance to understand the molecular mechanisms that are regulated by xenobiotic receptors. In this review, three major xenobiotic receptors will be discussed, being the aryl hydrocarbon receptor (AhR), pregnane X receptor (PXR) and the constitutive androstane receptor (CAR). Specifically, this review will focus on recent insights into the metabolic functions of these receptors, especially in the field of lipid metabolism and the associated dyslipidemia.
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Affiliation(s)
- Leonida Rakateli
- Institute for Molecular Cardiovascular Research (IMCAR), RWTH Aachen University, 52074 Aachen, Germany; (L.R.); (R.H.)
- Aachen-Maastricht Institute for CardioRenal Disease (AMICARE), RWTH Aachen University, 52074 Aachen, Germany
| | - Rosanna Huchzermeier
- Institute for Molecular Cardiovascular Research (IMCAR), RWTH Aachen University, 52074 Aachen, Germany; (L.R.); (R.H.)
- Aachen-Maastricht Institute for CardioRenal Disease (AMICARE), RWTH Aachen University, 52074 Aachen, Germany
| | - Emiel P. C. van der Vorst
- Institute for Molecular Cardiovascular Research (IMCAR), RWTH Aachen University, 52074 Aachen, Germany; (L.R.); (R.H.)
- Aachen-Maastricht Institute for CardioRenal Disease (AMICARE), RWTH Aachen University, 52074 Aachen, Germany
- Institute for Cardiovascular Prevention (IPEK), Ludwig-Maximilians-University Munich, 80336 Munich, Germany
- Interdisciplinary Center for Clinical Research (IZKF), RWTH Aachen University, 52074 Aachen, Germany
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2
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Kumbale CM, Zhang Q, Voit EO. Hepatic cholesterol biosynthesis and dioxin-induced dysregulation: A multiscale computational approach. Food Chem Toxicol 2023; 181:114086. [PMID: 37820785 PMCID: PMC10841405 DOI: 10.1016/j.fct.2023.114086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 09/18/2023] [Accepted: 10/03/2023] [Indexed: 10/13/2023]
Abstract
Humans are constantly exposed to lipophilic persistent organic pollutants (POPs) that accumulate in fatty foods. Among the numerous POPs, dioxins, in particular 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), can impact several organ systems. While the hazard is clearly recognized, it is still difficult to develop a comprehensive understanding of the overall health impacts of dioxins. As chemical toxicity testing is steadily adopting new approach methodologies (NAMs), it becomes imperative to develop computational models that can bridge the data gaps between in vitro testing and in vivo outcomes. As an effort to address this challenge, we propose a multiscale computational approach using a "template-and-anchor" (T&A) structure. A template is a high-level umbrella model that permits the integration of information from various, detailed anchor models. In the present study, we use this T&A approach to describe the effect of TCDD on cholesterol dynamics. Specifically, we represent hepatic cholesterol biosynthesis as an anchor model that is perturbed by TCDD, leading to steatosis, along with alterations of plasma cholesterol. In the future, incorporating pertinent information from all anchor models into the template model will allow the characterization of the global effects of dioxin, which can subsequently be translated into overall - and ultimately personalized - human health risk assessment.
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Affiliation(s)
- Carla M Kumbale
- Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
| | - Qiang Zhang
- Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA.
| | - Eberhard O Voit
- Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
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3
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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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4
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Krishnan S, Ding Y, Saedi N, Choi M, Sridharan GV, Sherr DH, Yarmush ML, Alaniz RC, Jayaraman A, Lee K. Gut Microbiota-Derived Tryptophan Metabolites Modulate Inflammatory Response in Hepatocytes and Macrophages. Cell Rep 2019; 23:1099-1111. [PMID: 29694888 PMCID: PMC6392449 DOI: 10.1016/j.celrep.2018.03.109] [Citation(s) in RCA: 346] [Impact Index Per Article: 69.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 02/11/2018] [Accepted: 03/22/2018] [Indexed: 12/12/2022] Open
Abstract
The gut microbiota plays a significant role in the progression of fatty liver disease; however, the mediators and their mechanisms remain to be elucidated. Comparing metabolite profile differences between germ-free and conventionally raised mice against differences between mice fed a low- and high-fat diet (HFD), we identified tryptamine and indole-3-acetate (I3A) as metabolites that depend on the microbiota and are depleted under a HFD. Both metabolites reduced fatty-acid- and LPS-stimulated production of pro-inflammatory cytokines in macrophages and inhibited the migration of cells toward a chemokine, with I3A exhibiting greater potency. In hepatocytes, I3A attenuated inflammatory responses under lipid loading and reduced the expression of fatty acid synthase and sterol regulatory element-binding protein-1c. These effects were abrogated in the presence of an aryl-hydrocarbon receptor (AhR) antagonist, indicating that the effects are AhR dependent. Our results suggest that gut microbiota could influence inflammatory responses in the liver through metabolites engaging host receptors.
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Affiliation(s)
- Smitha Krishnan
- Department of Chemical and Biological Engineering, Tufts University, Medford, MA 02155, USA
| | - Yufang Ding
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Nima Saedi
- Center for Engineering in Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Maria Choi
- Department of Chemical and Biological Engineering, Tufts University, Medford, MA 02155, USA
| | - Gautham V Sridharan
- Department of Chemical and Biological Engineering, Tufts University, Medford, MA 02155, USA
| | - David H Sherr
- Department of Environmental Health, Boston University School of Public Health, Boston, MA 02118, USA
| | - Martin L Yarmush
- Center for Engineering in Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Robert C Alaniz
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas Health Science Center, Texas A&M University, College Station, TX, USA
| | - Arul Jayaraman
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA; Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas Health Science Center, Texas A&M University, College Station, TX, USA; Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX 77843, USA.
| | - Kyongbum Lee
- Department of Chemical and Biological Engineering, Tufts University, Medford, MA 02155, USA.
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5
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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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6
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Pelclova D, Urban P, Fenclova Z, Vlckova S, Ridzon P, Kupka K, Meckova Z, Bezdicek O, Navratil T, Rosmus J, Zakharov S. Neurological and Neurophysiological Findings in Workers with Chronic 2,3,7,8‐Tetrachlorodibenzo‐
p
‐Dioxin Intoxication 50 Years After Exposure. Basic Clin Pharmacol Toxicol 2017; 122:271-277. [DOI: 10.1111/bcpt.12899] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 08/09/2017] [Indexed: 11/26/2022]
Affiliation(s)
- Daniela Pelclova
- Department of Occupational Medicine First Faculty of Medicine Charles University and General University Hospital in Prague Prague Czech Republic
| | - Pavel Urban
- Department of Occupational Medicine First Faculty of Medicine Charles University and General University Hospital in Prague Prague Czech Republic
- National Institute of Public Health Prague Czech Republic
| | - Zdenka Fenclova
- Department of Occupational Medicine First Faculty of Medicine Charles University and General University Hospital in Prague Prague Czech Republic
| | - Stepanka Vlckova
- Department of Occupational Medicine First Faculty of Medicine Charles University and General University Hospital in Prague Prague Czech Republic
| | - Petr Ridzon
- Department of Occupational Medicine First Faculty of Medicine Charles University and General University Hospital in Prague Prague Czech Republic
| | - Karel Kupka
- Institute of Nuclear Medicine First Faculty of Medicine Charles University and General University Hospital in Prague Prague Czech Republic
| | - Zuzana Meckova
- Institute of Nuclear Medicine First Faculty of Medicine Charles University and General University Hospital in Prague Prague Czech Republic
| | - Ondrej Bezdicek
- Department of Neurology First Faculty of Medicine Charles University and General University Hospital in Prague Prague Czech Republic
| | - Tomas Navratil
- J. Heyrovsky Institute of Physical Chemistry of the CAS, v.v.i. Prague Czech Republic
- Institute of Biochemistry and Laboratory Diagnostics First Faculty of Medicine Charles University and General University Hospital in Prague Prague Czech Republic
| | - Jan Rosmus
- State Veterinary Institute Prague Chemistry Czech Republic
| | - Sergey Zakharov
- Department of Occupational Medicine First Faculty of Medicine Charles University and General University Hospital in Prague Prague Czech Republic
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7
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Yu Y, Liu Q, Guo S, Zhang Q, Tang J, Liu G, Kong D, Li J, Yan S, Wang R, Wang P, Su X, Yu Y. 2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin promotes endothelial cell apoptosis through activation of EP3/p38MAPK/Bcl-2 pathway. J Cell Mol Med 2017; 21:3540-3551. [PMID: 28699682 PMCID: PMC5706494 DOI: 10.1111/jcmm.13265] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Accepted: 05/02/2017] [Indexed: 12/18/2022] Open
Abstract
Endothelial injury or dysfunction is an early event in the pathogenesis of atherosclerosis. Epidemiological and animal studies have shown that 2, 3, 7, 8‐tetrachlorodibenzo‐p‐dioxin (TCDD) exposure increases morbidity and mortality from chronic cardiovascular diseases, including atherosclerosis. However, whether or how TCDD exposure causes endothelial injury or dysfunction remains largely unknown. Cultured human umbilical vein endothelial cells (HUVECs) were exposed to different doses of TCDD, and cell apoptosis was examined. We found that TCDD treatment increased caspase 3 activity and apoptosis in HUVECs in a dose‐dependent manner,at doses from 10 to 40 nM. TCDD increased cyclooxygenase enzymes (COX)‐2 expression and its downstream prostaglandin (PG) production (mainly PGE2 and 6‐keto‐PGF1α) in HUVECs. Interestingly, inhibition of COX‐2, but not COX‐1, markedly attenuated TCDD‐triggered apoptosis in HUVECs. Pharmacological inhibition or gene silencing of the PGE2 receptor subtype 3 (EP3) suppressed the augmented apoptosis in TCDD‐treated HUVECs. Activation of the EP3 receptor enhanced p38 MAPK phosphorylation and decreased Bcl‐2 expression following TCDD treatment. Both p38 MAPK suppression and Bcl‐2 overexpression attenuated the apoptosis in TCDD‐treated HUVECs. TCDD increased EP3‐dependent Rho activity and subsequently promoted p38MAPK/Bcl‐2 pathway‐mediated apoptosis in HUVECs. In addition, TCDD promoted apoptosis in vascular endothelium and delayed re‐endothelialization after femoral artery injury in wild‐type (WT) mice, but not in EP3−/− mice. In summary, TCDD promotes endothelial apoptosis through the COX‐2/PGE2/EP3/p38MAPK/Bcl‐2 pathway. Given the cardiovascular hazard of a COX‐2 inhibitor, our findings indicate that the EP3 receptor and its downstream pathways may be potential targets for prevention of TCDD‐associated cardiovascular diseases.
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Affiliation(s)
- Yu Yu
- Department of Pharmacology, Tianjin Medical University, Tianjin, China.,Department of Pediatric Cardiology, Xinhua Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qian Liu
- Department of Pharmacology, Tianjin Medical University, Tianjin, China.,Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Shumin Guo
- Department of Pharmacology, Tianjin Medical University, Tianjin, China.,Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Qianqian Zhang
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Juan Tang
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Guizhu Liu
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Deping Kong
- Department of Pharmacology, Tianjin Medical University, Tianjin, China.,Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Juanjuan Li
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Shuai Yan
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Ruiguo Wang
- Institute of Quality Standards and Testing Technology for Agro-products, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Peilong Wang
- Institute of Quality Standards and Testing Technology for Agro-products, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xiaoou Su
- Institute of Quality Standards and Testing Technology for Agro-products, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Ying Yu
- Department of Pharmacology, Tianjin Medical University, Tianjin, China.,Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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Hara F, Tatebe J, Watanabe I, Yamazaki J, Ikeda T, Morita T. Molecular Hydrogen Alleviates Cellular Senescence in Endothelial Cells. Circ J 2016; 80:2037-46. [PMID: 27477846 DOI: 10.1253/circj.cj-16-0227] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Substantial evidence indicates that molecular hydrogen (H2) has beneficial vascular effects because of its antioxidant and/or anti-inflammatory effects. Thus, hydrogen-rich water may prove to be an effective anti-aging drink. This study examined the effects of H2on endothelial senescence and clarified the mechanisms involved. METHODS AND RESULTS Hydrogen-rich medium was produced by a high-purity hydrogen gas generator. Human umbilical vein endothelial cells (HUVECs) were incubated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for various time periods in normal or hydrogen-rich medium. The baseline H2concentration in hydrogen-rich medium was 0.55±0.07 mmol/L. This concentration gradually decreased, and H2was almost undetectable in medium after 12 h. At 24 h after TCDD exposure, HUVECs treated with TCDD exhibited increased 8OHdG and acetyl-p53 expression, decreased nicotinamide adenine dinucleotide (NAD(+))/NADH ratio, impaired Sirt1 activity, and enhanced senescence-associated β-galactosidase. However, HUVECs incubated in hydrogen-rich medium did not exhibit these TCDD-induced changes accompanying Nrf2 activation, which was observed even after H2was undetectable in the medium. Chrysin, an inhibitor of Nrf2, abolished the protective effects of H2on HUVECs. CONCLUSIONS H2has long-lasting antioxidant and anti-aging effects on vascular endothelial cells through the Nrf2 pathway, even after transient exposure to H2. Hydrogen-rich water may thus be a functional drink that increases longevity. (Circ J 2016; 80: 2037-2046).
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Affiliation(s)
- Fumihiko Hara
- Department of Cardiovascular Medicine, Toho University School of Medicine
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9
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The aryl hydrocarbon receptor promotes aging phenotypes across species. Sci Rep 2016; 6:19618. [PMID: 26790370 PMCID: PMC4726214 DOI: 10.1038/srep19618] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 12/16/2015] [Indexed: 02/06/2023] Open
Abstract
The ubiquitously expressed aryl hydrocarbon receptor (AhR) induces drug metabolizing enzymes as well as regulators of cell growth, differentiation and apoptosis. Certain AhR ligands promote atherosclerosis, an age-associated vascular disease. Therefore, we investigated the role of AhR in vascular functionality and aging. We report a lower pulse wave velocity in young and old AhR-deficient mice, indicative of enhanced vessel elasticity. Moreover, endothelial nitric oxide synthase (eNOS) showed increased activity in the aortas of these animals, which was reflected in increased NO production. Ex vivo, AhR activation reduced the migratory capacity of primary human endothelial cells. AhR overexpression as well as treatment with a receptor ligand, impaired eNOS activation and reduced S-NO content. All three are signs of endothelial dysfunction. Furthermore, AhR expression in blood cells of healthy human volunteers positively correlated with vessel stiffness. In the aging model Caenorhabditis elegans, AhR-deficiency resulted in increased mean life span, motility, pharynx pumping and heat shock resistance, suggesting healthier aging. Thus, AhR seems to have a negative impact on vascular and organismal aging. Finally, our data from human subjects suggest that AhR expression levels could serve as an additional, new predictor of vessel aging.
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10
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Tavakoly Sany SB, Hashim R, Salleh A, Rezayi M, Karlen DJ, Razavizadeh BBM, Abouzari-Lotf E. Dioxin risk assessment: mechanisms of action and possible toxicity in human health. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:19434-50. [PMID: 26514567 DOI: 10.1007/s11356-015-5597-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 10/08/2015] [Indexed: 05/11/2023]
Abstract
Dioxin-like compounds (DLCs) have been classified by the World Health Organization (WHO) as one of the most persistent toxic chemical substances in the environment, and they are associated with several occupational activities and industrial accidents around the world. Since the end of the 1970s, these toxic chemicals have been banned because of their human toxicity potential, long half-life, wide dispersion, and they bioaccumulate in the food web. This review serves as a primer for environmental health professionals to provide guidance on short-term risk assessment of dioxin and to identify key findings for health and exposure assessment based on policies of different agencies. It also presents possible health effects of dioxins, mechanisms of action, toxic equivalency factors (TEFs), and dose-response characterization. Key studies related to toxicity values of dioxin-like compounds and their possible human health risk were identified through PubMed and supplemented with relevant studies characterized by reviewing the reference lists in the review articles and primary literature. Existing data decreases the scope of analyses and models in relevant studies to a manageable size by focusing on the set of important studies related to the perspective of developing toxicity values of DLCs.
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Affiliation(s)
| | - Rosli Hashim
- Institute of Biological Sciences, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Aishah Salleh
- Institute of Biological Sciences, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Majid Rezayi
- Chemistry Department, Faculty of Science, University Malaya, 50603, Kuala Lumpur, Malaysia
| | - David J Karlen
- Environmental Protection Commission of Hillsborough County, 3629 Queen Palm Drive, Tampa, FL, 33619-1309, USA
| | - Bi Bi Marzieh Razavizadeh
- Department of Food Chemistry, Research Institute of Food Science and Technology, P.O. Box: 91735-147, Mashhad, Iran
| | - Ebrahim Abouzari-Lotf
- Advanced Materials Research Group, Institute of Hydrogen Economy, Universiti Teknologi Malaysia, International Campus, 54100, Kuala Lumpur, Malaysia
- Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, 54100, Kuala Lumpur, Malaysia
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11
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Xue Y, Shui X, Su W, He Y, Lu X, Zhang Y, Yan G, Huang S, Lei W, Chen C. Baicalin inhibits inflammation and attenuates myocardial ischaemic injury by aryl hydrocarbon receptor. ACTA ACUST UNITED AC 2015; 67:1756-64. [PMID: 26407904 DOI: 10.1111/jphp.12484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 07/28/2015] [Indexed: 12/19/2022]
Abstract
OBJECTIVES Recent evidence indicates that suppressing inflammation by specific drug target and treatment measures contributes to attenuate ischaemic injury and the related heart diseases. This study aimed to investigate the potential effect of baicalin on myocardial ischaemic injury through inhibition of inflammation by inactivating the aryl hydrocarbon receptor (AhR). METHODS The mouse model with myocardial ischaemic injury was prepared by the left anterior descending coronary artery-amputation and then treated using baicalin. After observing the expression of AhR by immunohistochemical staining, the AhR and inflammatory mediators in circulation and myocardial tissues, including high-sensitive C-reactive protein (hsCRP), interleukin (IL)-1β and IL-6, were detected based on enzyme-linked immunosorbent assay, real-time polymerase chain reaction and Western blot methods. KEY FINDINGS The results showed that (1) substantial expression of AhR was observed in myocardial tissues; (2) ischaemic injury caused myocardial necrosis and remodelling, and stimulated hsCRP, IL-1β and IL-6 by activation of AhR; and (3) baicalin alleviated the myocardial injury and inflammatory response by inhibiting the expression of AhR. CONCLUSION Our findings extend the list of AhR ligands beyond exogenous toxins and endogenous molecules to cardiac immunological factors, and moreover it could be considered potential drug targets due to its pathological modulatory properties, while baicalin demonstrated promise as a novel vehicle for ischaemic heart disease.
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Affiliation(s)
- Yiqiang Xue
- Cardiovascular Medicine Center, Affiliated Hospital of Guangdong Medical College, Zhanjiang, China
| | - Xiaorong Shui
- Laboratory of Vascular Surgery, Guangdong Medical College, Zhanjiang, China
| | - Weiqing Su
- Department of Cardiovascular Medicine, The People's Hospital of Lianjiang, Zhanjiang, China
| | - Yuan He
- Laboratory of Cardiovascular Diseases, Guangdong Medical College, Zhanjiang, China
| | - Xinlin Lu
- Cardiovascular Medicine Center, Affiliated Hospital of Guangdong Medical College, Zhanjiang, China
| | - Yu Zhang
- Cardiovascular Medicine Center, Affiliated Hospital of Guangdong Medical College, Zhanjiang, China
| | - Guosen Yan
- Cardiovascular Medicine Center, Affiliated Hospital of Guangdong Medical College, Zhanjiang, China.,Laboratory of Cardiovascular Diseases, Guangdong Medical College, Zhanjiang, China
| | - Shian Huang
- Cardiovascular Medicine Center, Affiliated Hospital of Guangdong Medical College, Zhanjiang, China
| | - Wei Lei
- Cardiovascular Medicine Center, Affiliated Hospital of Guangdong Medical College, Zhanjiang, China.,Laboratory of Cardiovascular Diseases, Guangdong Medical College, Zhanjiang, China
| | - Can Chen
- Cardiovascular Medicine Center, Affiliated Hospital of Guangdong Medical College, Zhanjiang, China.,Laboratory of Cardiovascular Diseases, Guangdong Medical College, Zhanjiang, China
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12
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Huang S, Shui X, He Y, Xue Y, Li J, Li G, Lei W, Chen C. AhR expression and polymorphisms are associated with risk of coronary arterial disease in Chinese population. Sci Rep 2015; 5:8022. [PMID: 25620626 PMCID: PMC4306136 DOI: 10.1038/srep08022] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 12/29/2014] [Indexed: 11/15/2022] Open
Abstract
The aryl hydrocarbon receptor (AhR) mediates the control of environmental toxicity, and modulates the development and pathogenesis of the cardiovascular system. However, little is known about the role of AhR in coronary arterial disease (CAD) susceptibility. We therefore conducted a case-control study in a Chinese population, and assessed the potential association between AhR variants and CAD susceptibility. Compared with the controls, circulating AhR expression was found to be significantly increased in patients with CAD and its subtypes including ST-segment and non-ST-segment elevation myocardial infarction, and stable and unstable angina pectoris. Receiver operating characteristic (ROC) analysis to evaluate the effect of AhR on CAD progression showed it to be a potent biomarker for CAD. Genotype frequencies of AhR rs2066853 differed significantly between CAD and control subjects, while smoking and hyperlipidemia markedly promoted CAD risk relative to the AhR polymorphism. Moreover, a significant difference in AhR variant distribution was observed between the four CAD subtypes with different severities. The expression level and functional polymorphisms of circulating AhR may affect the susceptibility and progression of CAD in Chinese populations. This provides a novel view of the etiology and epidemiology of CAD, and will contribute to the diagnosis and therapy of this severe disease.
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Affiliation(s)
- Shian Huang
- 1] Laboratory of Cardiovascular Diseases, Guangdong Medical College, Zhanjiang 524001, China [2] Department of Cardiovascular Medicine, Affiliated Hospital of Guangdong Medical College, Zhanjiang 524001, China
| | - Xiaorong Shui
- Laboratory of Vascular Surgery, Guangdong Medical College, Zhanjiang 524001, China
| | - Yuan He
- Laboratory of Cardiovascular Diseases, Guangdong Medical College, Zhanjiang 524001, China
| | - Yiqiang Xue
- Department of Cardiovascular Medicine, Affiliated Hospital of Guangdong Medical College, Zhanjiang 524001, China
| | - Jianwen Li
- Laboratory of Vascular Surgery, Guangdong Medical College, Zhanjiang 524001, China
| | - Guoming Li
- Department of Cardiovascular Medicine, Affiliated Hospital of Guangdong Medical College, Zhanjiang 524001, China
| | - Wei Lei
- 1] Laboratory of Cardiovascular Diseases, Guangdong Medical College, Zhanjiang 524001, China [2] Department of Cardiovascular Medicine, Affiliated Hospital of Guangdong Medical College, Zhanjiang 524001, China
| | - Can Chen
- 1] Laboratory of Cardiovascular Diseases, Guangdong Medical College, Zhanjiang 524001, China [2] Department of Cardiovascular Medicine, Affiliated Hospital of Guangdong Medical College, Zhanjiang 524001, China
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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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Abstract
The pregnane X receptor (PXR) and constitutive androstane receptor (CAR), 2 closely related and liver-enriched members of the nuclear receptor superfamily, and aryl hydrocarbon receptor (AhR), a nonnuclear receptor transcription factor (TF), are major receptors/TFs regulating the expression of genes for the clearance and detoxification of xenobiotics. They are hence defined as "xenobiotic receptors". Recent studies have demonstrated that PXR, CAR and AhR also regulate the expression of key proteins involved in endobiotic responses such as the metabolic homeostasis of lipids, glucose, and bile acid, and inflammatory processes. It is suggested that the functions of PXR, CAR and AhR may be closely implicated in the pathogeneses of metabolic vascular diseases, such as hyperlipidemia, atherogenesis, and hypertension. Therefore, manipulation of the activities of these receptors may provide novel strategies for the treatment of vascular diseases. Here, we review the pathophysiological roles of PXR, CAR and AhR in the vascular system.
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Affiliation(s)
- Lei Xiao
- Cardiovascular Research Center, School of Medicine, Xi'an Jiaotong University
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15
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Indolic uremic solutes increase tissue factor production in endothelial cells by the aryl hydrocarbon receptor pathway. Kidney Int 2013; 84:733-44. [DOI: 10.1038/ki.2013.133] [Citation(s) in RCA: 172] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 02/04/2013] [Accepted: 02/07/2013] [Indexed: 11/08/2022]
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16
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Forgacs AL, Dere E, Angrish MM, Zacharewski TR. Comparative analysis of temporal and dose-dependent TCDD-elicited gene expression in human, mouse, and rat primary hepatocytes. Toxicol Sci 2013; 133:54-66. [PMID: 23418086 DOI: 10.1093/toxsci/kft028] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD)-elicited time- and dose-dependent differential gene expression was compared in human, mouse, and rat primary hepatocytes. Comprehensive time course (10 nM TCDD or dimethyl sulfoxide vehicle control for 1, 2, 4, 8, 12, 24, and 48h) studies identified 495, 2305, and 711 differentially expressed orthologous genes in human, mouse, and rat hepatocytes, respectively. However, only 16 orthologs were differentially expressed across all three species, with the majority of orthologs exhibiting species-specific expression (399 human, 2097 mouse, and 533 rat), consistent with species-specific expression reported in other in vitro and in vivo comparative studies. TCDD also elicited the dose-dependent induction of 397 human, 100 mouse, and 443 rat genes at 12h and 615 human, 426 mouse, and 314 rat genes at 24h. Comparable EC50 values were obtained for AhR battery genes including Cyp1a1 (0.1 nM human, 0.05 nM mouse, 0.08 nM rat at 24h) and Tiparp (0.97 nM human, 0.63 nM mouse, 0.14 nM rat at 12h). Overrepresented functions and pathways included amino acid metabolism in humans, immune response in mice, and energy homeostasis in rats. Differentially expressed genes functionally associated with lipid transport, processing, and metabolism were overrepresented in all three species but exhibited species-specific expression consistent with the induction of hepatic steatosis in mice but not in rats following a single oral gavage of TCDD. Furthermore, human primary hepatocytes showed lipid accumulation following 48h of treatment with TCDD, suggesting that AhR-mediated steatosis in mice more closely resembles human hepatic fat accumulation compared with that in rats. Collectively, these results suggest that species-specific gene expression profiles mediate the species-specific effects of TCDD despite the conservation of the AhR and its signaling mechanism.
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Affiliation(s)
- Agnes L Forgacs
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
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Lee DH, Lind PM, Jacobs DR, Salihovic S, van Bavel B, Lind L. Background exposure to persistent organic pollutants predicts stroke in the elderly. ENVIRONMENT INTERNATIONAL 2012; 47:115-20. [PMID: 22809777 DOI: 10.1016/j.envint.2012.06.009] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Revised: 05/31/2012] [Accepted: 06/16/2012] [Indexed: 05/20/2023]
Abstract
Background exposure to persistent organic pollutants (POPs), lipophilic xenobiotics that accumulate mainly in adipose tissue, has recently emerged as a new risk factor for cardiovascular diseases. This prospective study was performed to evaluate if plasma concentrations of selected POPs predict incident stroke among the elderly. Twenty-one POPs (including 16 polychlorinated biphenyl (PCB) congeners, 3 organochlorine (OC) pesticides, 1 brominated diphenyl ether (BDE), and 1 dioxin) were measured in plasma collected at baseline in 898 participants aged 70 years of the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS). Stroke diagnosis was validated by hospital records. During the five year follow-up, 35 subjects developed hospital-treated stroke. After adjusting for known stroke risk factors, most PCBs with 4, 5, or 6 chlorine atoms, p,p'-DDE, trans-nonachlor, and octachlorodibenzo-p-dioxin significantly predicted the risk of stroke. Across quartiles of summary measures of PCBs and OC pesticides, the adjusted ORs were 1.0, 0.8 (95% confidence interval: 0.2-2.5), 1.2 (0.4-3.4), and 2.1 (0.7-6.2) for PCBs and 1.0, 1.2 (0.3-4.2), 2.3 (0.7-6.9), and 3.0 (1.0-9.4) for OC pesticides (P for trend=0.11 and 0.03, respectively). The adjusted ORs among participants ≥ 90th percentile of the summary measures were 5.5 (1.7-18.1) for PCBs and 4.0 (1.1-14.6) for OC pesticides; corresponding ORs for those ≥ 95th percentile were 7.8 (2.1-29.6) and 9.5 (2.3-38.9). Background exposure to POPs may play an important role in development or progression of stroke in the elderly.
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Affiliation(s)
- Duk-Hee Lee
- Department of Preventative Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
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Angrish MM, Dominici CY, Zacharewski TR. TCDD-elicited effects on liver, serum, and adipose lipid composition in C57BL/6 mice. Toxicol Sci 2012; 131:108-15. [PMID: 22977169 DOI: 10.1093/toxsci/kfs277] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The aryl hydrocarbon receptor (AhR) mediates alterations in hepatic lipid composition elicited by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In order to further investigate the effects of TCDD, liver, serum, and gonadal white adipose tissue (gWAT) fatty acid methyl esters (FAMEs) and lipids were examined in fasted 4-week-old female mice orally gavaged with 30 µg/kg TCDD at 24, 72, and 168 h postdose. Mean hepatic FAME levels increased (236.7 µmol/g in controls compared with 392.2 µmol/g in TCDD treated) with minimal changes in gWAT and serum. In the liver, TCDD decreased saturated fatty acids (SFAs 16:0, 18:0, 20:0, and 22:0) and increased monounsaturated fatty acids (MUFAs 16:1n7, 18:1n9, and 20:1n9). Hepatic polyunsaturated fatty acids (PUFAs) 20:2n6, 20:3n6, 18:3n3, and 22:5n3 also increased, whereas 20:4n6 and 22:6n3 levels decreased. gWAT PUFAs 20:2n6 and 20:3n6 exhibited modest increases, whereas serum 18:0 decreased and 18:1n9 increased. Serum analyses also identified a ~25% decrease in total cholesterol (CHOL), low-density lipoprotein (LDL), and high-density lipoprotein following TCDD treatment. The decrease in serum CHOL was consistent with the induction of hepatic reverse CHOL transport genes Lcat (2.0-fold), Apoa1 (1.7-fold), and Ldlr (3.6-fold), and the repression of CHOL biosynthesis genes Hmgcs1 (-2.1-fold) and Hmgcr (-2.3-fold). In addition, TCDD decreased serum Apob100 (4.4-fold) and Apob48 (2.2-fold) protein levels, suggesting serum lipid clearance and decreased hepatic efflux. Collectively, the TCDD-elicited decreases in serum lipid levels are consistent with AhR-mediated enhancement of dietary fat distribution to the liver.
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Affiliation(s)
- Michelle Manente Angrish
- Genetics Program, Center for Integrative ToxicologyMichigan State University, East Lansing, Michigan 48824, USA
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Tanos R, Murray IA, Smith PB, Patterson A, Perdew GH. Role of the Ah receptor in homeostatic control of fatty acid synthesis in the liver. Toxicol Sci 2012; 129:372-9. [PMID: 22696238 DOI: 10.1093/toxsci/kfs204] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We have previously demonstrated a role for the aryl hydrocarbon receptor (AHR) in the attenuation of the cholesterol biosynthesis pathway. This regulation did not require that the AHR binds to its cognate response element. Based on these observations and other reports depicting a role for AHR in lipid metabolism, we chose to investigate the involvement of the receptor in the regulation of the fatty acid synthesis pathway in mice and humans. For this purpose, C57BL/6J, liver-specific transgenic DRE-binding mutant AhR (A78D-AhrTtr CreAlb Ahrfx/fx) and CreAlb Ahrfx/fx mice were treated with an AHR ligand, and hepatic mRNA expression levels of key fatty acid genes (e.g., Acaca, Fasn, Scd1) were measured. The basal levels of those genes were also compared between C57BL6/J and hepatic AHR-deficient mice, as well as between Ahb and Ahd congenic mice. To extend these results to humans, fatty acid gene expression in human cells were compared with AHR-silenced cells. In addition, primary human hepatocytes were treated with an AHR ligand to assess alterations in gene expression and fatty acid synthesis. These studies indicated that the AHR constitutively attenuates the expression of key fatty acid synthesis genes in the absence of binding to its cognate response element. In addition, activation of AHR led to further repression of the expression of these genes and a decrease in overall fatty acid synthesis and secretion in human hepatocytes. Based on our results, we can conclude that increased AHR activity represses fatty acid synthesis, suggesting it may be a future therapeutic target.
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Affiliation(s)
- Rachel Tanos
- Department of Veterinary and Biomedical Sciences, Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Angrish MM, Jones AD, Harkema JR, Zacharewski TR. Aryl hydrocarbon receptor-mediated induction of Stearoyl-CoA desaturase 1 alters hepatic fatty acid composition in TCDD-elicited steatosis. Toxicol Sci 2011; 124:299-310. [PMID: 21890736 DOI: 10.1093/toxsci/kfr226] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
2,3,7,8-tetrachlorodibenzo-ρ-dioxin (TCDD) induces hepatic dyslipidemia mediated by the aryl hydrocarbon receptor (AhR). Stearoyl-CoA desaturase 1 (Scd1) performs the rate-limiting step in monounsaturated fatty acid (MUFA) synthesis, desaturating 16:0 and 18:0 into 16:1n7 and 18:1n9, respectively. To further examine the role of Scd1 in TCDD-induced hepatotoxicity, comparative studies were performed in Scd1(+/+) and Scd1(-/-) mice treated with 30 μg/kg TCDD. TCDD induced Scd1 activity, protein, and messenger RNA (mRNA) levels approximately twofold. In Scd1(+/+) mice, hepatic effects were marked by increased vacuolization and inflammation and a 3.5-fold increase in serum alanine aminotransferase (ALT) levels. Hepatic triglycerides (TRGs) were induced 3.9-fold and lipid profiling by gas chromatography-mass spectroscopy measured a 1.9-fold increase in fatty acid (FA) levels, consistent with the induction of lipid transport genes. Induction of Scd1 altered FA composition by decreasing saturated fatty acid (SFA) molar ratios 8% and increasing MUFA molar ratios 9%. Furthermore, ChIP-chip analysis revealed AhR enrichment (up to 5.7-fold), and computational analysis identified 16 putative functional dioxin response elements (DREs) within Scd1 genomic loci. Band shift assays confirmed AhR binding with select DREs. In Scd1(-/-) mice, TCDD induced minimal hepatic vacuolization and inflammation, while serum ALT levels remained unchanged. Although Scd1 deficiency attenuated TCDD-induced TRG accumulation, overall FA levels remained unchanged compared with Scd1(+/+) mice. In Scd1(-/-) mice, TCDD induced SFA ratios 8%, reduced MUFA ratios 13%, and induced polyunsaturated fatty acid ratios 5% relative to treated Scd1(+/+) mice. Collectively, these results suggest that AhR regulation of Scd1 not only alters lipid composition but also contributes to the hepatotoxicity of TCDD.
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Affiliation(s)
- Michelle M Angrish
- Genetics Program, Michigan State University, East Lansing, Michigan 48824, USA
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Min JY, Cho JS, Lee KJ, Park JB, Park SG, Kim JY, Min KB. Potential role for organochlorine pesticides in the prevalence of peripheral arterial diseases in obese persons: Results from the National Health and Nutrition Examination Survey 1999–2004. Atherosclerosis 2011; 218:200-6. [DOI: 10.1016/j.atherosclerosis.2011.04.044] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2011] [Revised: 04/27/2011] [Accepted: 04/29/2011] [Indexed: 12/21/2022]
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Wu D, Nishimura N, Kuo V, Fiehn O, Shahbaz S, Winkle LV, Matsumura F, Vogel C. Activation of aryl hydrocarbon receptor induces vascular inflammation and promotes atherosclerosis in apolipoprotein E-/- mice. Arterioscler Thromb Vasc Biol 2011; 31:1260-7. [PMID: 21441140 PMCID: PMC3098318 DOI: 10.1161/atvbaha.110.220202] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Exposure to dioxins has been shown to contribute to the development of inflammatory diseases, such as atherosclerosis. Macrophage-mediated inflammation is a critical event in the initiation of atherosclerosis. Previously, we showed that treatment of macrophages with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) leads to aryl hydrocarbon receptor (AhR)-dependent activation of inflammatory mediators and the formation of cholesterol-laden foam cells. However, the mechanisms responsible for the formation of atherosclerotic lesions mediated through AhR have not been identified. METHODS AND RESULTS An in vitro macrophage and an apolipoprotein E (ApoE)-/- mouse model were used to determine whether chemokines and their receptors are responsible for the AhR-mediated atherogenesis. Exposure of ApoE-/- mice to TCDD caused a time-dependent progression of atherosclerosis, which was associated with induction of inflammatory genes, including interleukin-8, as well as F4/80 and matrix metalloproteinase-12. A high-fat diet enhanced the TCDD-mediated inflammatory response and aggravated the formation of complex atheromas. Treatment with a CXCR2 inhibitor and an AhR antagonist reduced the TCDD-induced progression of early atherosclerotic lesions in ApoE-/- mice. CONCLUSION The results suggest that CXCR2 mediates the atherogenic activity of environmental pollutants, such as dioxins, and contributes to the development of atherosclerosis through the induction of a vascular inflammatory response by activating the AhR-signaling pathway.
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Affiliation(s)
- Dalei Wu
- Department of Environmental Toxicology, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
- Center for Health and the Environment, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Noriko Nishimura
- Endocrine Disruptors and Dioxin Research Project, National Institute for Environmental Studies, Tsukuba 305-8506, Japan
| | - Victoria Kuo
- Center for Health and the Environment, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Oliver Fiehn
- Department of Molecular and Cellular Biology & Genome Center, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Sevini Shahbaz
- Department of Molecular and Cellular Biology & Genome Center, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Laura Van Winkle
- Center for Health and the Environment, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Fumio Matsumura
- Department of Environmental Toxicology, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
- Center for Health and the Environment, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Christoph Vogel
- Department of Environmental Toxicology, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
- Center for Health and the Environment, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
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Sergeev AV, Carpenter DO. Increased hospitalizations for ischemic stroke with comorbid diabetes and residential proximity to sources of organic pollutants: a 12-year population-based study. Neuroepidemiology 2010; 35:196-201. [PMID: 20664210 PMCID: PMC2945264 DOI: 10.1159/000316874] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Accepted: 06/09/2010] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Evidence is emerging that exposure to persistent organic pollutants (POP) is a risk factor for atherosclerosis-related diseases and for diabetes mellitus (DM). We hypothesized that residential proximity to sources of POP will be associated with an increase in hospitalization rates for ischemic stroke (IS) with comorbid DM (IS-DM). METHODS We examined IS-DM hospitalization rates in the New York State (exclusive of New York City) during a 12-year period. POP exposure status was assessed based on residency in a zip code containing or abutting environmental sources of POP. Adjusted relative risks (RR) of IS-DM hospitalization were estimated by multivariate Poisson regression. RESULTS A statistically significant 10% increase in IS-DM hospitalization rates was observed in populations environmentally exposed to POP (adjusted RR 1.10, 95% confidence interval, CI, 1.01-1.20; p = 0.031). IS-DM hospitalization rates were also higher in males (adjusted RR 1.34, 95% CI 1.30-1.39; p < 0.001), in blacks (adjusted RR 4.54, 95% CI 4.16-4.94; p < 0.001) and in older age groups (p for trend <0.001). CONCLUSIONS Residential proximity to sources of POP is associated with an increase in RR of IS-DM hospitalization. Our findings support the hypothesis of POP being a risk factor for IS. Further studies are warranted.
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Affiliation(s)
- Alexander V Sergeev
- School of Public Health Sciences and Professions, Ohio University, Athens, Ohio 45701, USA.
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Sergeev AV, Carpenter DO. Exposure to Persistent Organic Pollutants Increases Hospitalization Rates for Myocardial Infarction with Comorbid Hypertension. ACTA ACUST UNITED AC 2010; 2:1-9. [PMID: 21562627 DOI: 10.4137/ppri.s4332] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Studies suggest that environmental exposure to persistent organic pollutants (POPs) may be an emerging risk factor for ischemic heart disease, including acute myocardial infarction (AMI). However, some studies indicate that exposure to POPs may also be a risk factor for hypertension, a well-established risk factor for AMI. To investigate effect of POPs on the environmental burden of cardiovascular disease, a study of AMI with comorbid hypertension in populations environmentally exposed to persistent organic pollutants, based on the zip code of residence, was conducted. Data on hospital discharges for AMI with comorbid hypertension were obtained from the New York Statewide Planning and Research Cooperative System for 1993-2004. Patients residing in zip codes containing or abutting POPs contaminated sites were considered environmentally exposed. Relative risks (RR) - with corresponding 95% confidence intervals (95% CI) - of hospitalization for AMI with comorbid hypertension were estimated by Poisson regression, adjusting for known confounders. Adjusted hospitalization rates for AMI with comorbid hypertension were 12.4% higher in populations residing in proximity to a POPs site (adjusted RR = 1.124, 95% CI 1.025-1.233, p < 0.05), compared to not in proximity to a POPs site. Also, hospitalization rates for AMI with comorbid hypertension were higher in males than in females (adjusted RR = 2.157, 95% CI 2.100-2.215, p < 0.05), in African Americans than in Caucasians (adjusted RR = 1.631, 95% CI 1.483-1.794, p < 0.05), and in older age groups (p for trend <0.05). These findings are consistent with the established effects of non-modifiable risk factors and serve as indirect quality indicators for our model. In conclusion, our results support the hypothesis that environmental exposure to POPs increases the burden of cardiovascular disease in exposed populations.
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Affiliation(s)
- Alexander V Sergeev
- School of Public Health Sciences and Professions, Ohio University, Athens, OH, USA
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25
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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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Pelclová D, Prázny M, Skrha J, Fenclová Z, Kalousová M, Urban P, Navrátil T, Senholdová Z, Smerhovsky Z. 2,3,7,8-TCDD exposure, endothelial dysfunction and impaired microvascular reactivity. Hum Exp Toxicol 2008; 26:705-13. [PMID: 17984141 DOI: 10.1177/0960327107083971] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Vascular function was examined in subjects with long-term high level of serum 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) during their follow-up visits. Their earlier mean peak TCDD level at the time of exposure in 1965-1968 was estimated in the range of 3300-74 000 pg/g lipids. Ten former pesticide production workers heavily exposed to TCDD (age 57 +/- 2 years, TCDD about 170 pg/g lipids) were examined in 2001. Extended group of 15 TCDD-exposed men (age 59 +/- 3 years, TCDD about 130 pg/g lipids) underwent the same examination in 2004. Findings were compared with a control group of 14 healthy men (age 54 +/- 2 years). Skin microvascular reactivity (MVR) was measured by laser Doppler perfusion monitoring in the forearm during post-occlusive reactive hyperemia (PORH) and thermal hyperemia (TH). Several parameters of MVR in men exposed to TCDD were significantly impaired, compared with the control group and further progression of the impairment of MVR has been observed between years 2001 and 2004. Serum concentration of E-selectin and inhibitor of tissue plasminogen activator 1 (PAI-1) was significantly higher in exposed subjects (56.0 +/- 18.4 ng/mL versus 40.0 +/- 12.0 ng/mL, P = 0.022 and 90.9 +/- 33.3 ng/mL versus 45.0 +/- 18.0, P = 0.002, respectively). In addition, PORH in the forearm was significantly negatively associated with SOD activity (r = -0.77, P = 0.009) as well as the velocity of perfusion increase during TH (r = -0.68, P = 0.03) and TH% (r = -0.78, P = 0.008). Our data document the presence of endothelial dysfunction in TCDD-exposed men.
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Affiliation(s)
- Daniela Pelclová
- Department of Occupational Medicine, 1st Medical Faculty, Charles University and General University Hospital, Na Bojisti 1, Prague, Czech Republic.
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Hutt KJ, Shi Z, Albertini DF, Petroff BK. The environmental toxicant 2,3,7,8-tetrachlorodibenzo-p-dioxin disrupts morphogenesis of the rat pre-implantation embryo. BMC DEVELOPMENTAL BIOLOGY 2008; 8:1. [PMID: 18171477 PMCID: PMC2254588 DOI: 10.1186/1471-213x-8-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Accepted: 01/02/2008] [Indexed: 11/22/2022]
Abstract
Background Environmental toxicants, whose actions are often mediated through the aryl hydrocarbon receptor (AhR) pathway, pose risks to the health and well-being of exposed species, including humans. Of particular concern are exposures during the earliest stages of development that while failing to abrogate embryogenesis, may have long term effects on newborns or adults. The purpose of this study was to evaluate the effect of maternal exposure to the AhR-specific ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the development of rat pre-implantation embryos with respect to nuclear and cytoskeletal architecture and cell lineage allocation. Results We performed a systematic 3 dimensional (3D) confocal microscopy analysis of rat pre-implantation embryos following maternal exposure to environmentally relevant doses of TCDD. Both chronic (50 ng/kg/wk for 3 months) and acute (50 ng/kg and 1 μg/kg at proestrus) maternal TCDD exposure disrupted morphogenesis at the compaction stage (8–16 cell), with defects including monopolar spindle formation, f-actin capping and fragmentation due to aberrant cytokinesis. Additionally, the size, shape and position of nuclei were modified in compaction stage pre-implantation embryos collected from treated animals. Notably, maternal TCDD exposure did not compromise survival to blastocyst, which with the exception of nuclear shape, were morphologically similar to control blastocysts. Conclusion We have identified the compaction stage of pre-implantation embryogenesis as critically sensitive to the effects of TCDD, while survival to the blastocyst stage is not compromised. To the best of our knowledge this is the first in vivo study to demonstrate a critical window of pre-implantation mammalian development that is vulnerable to disruption by an AhR ligand at environmentally relevant doses.
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Affiliation(s)
- Karla J Hutt
- Department of Internal Medicine, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA.
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Kang HK, Dalager NA, Needham LL, Patterson DG, Lees PSJ, Yates K, Matanoski GM. Health status of Army Chemical Corps Vietnam veterans who sprayed defoliant in Vietnam. Am J Ind Med 2006; 49:875-84. [PMID: 17006952 DOI: 10.1002/ajim.20385] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND U.S. Army Chemical Corps veterans handled and sprayed herbicides in Vietnam resulting in exposure to Agent Orange and its contaminant 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD or dioxin). This study examined the long-term health effects associated with herbicide exposure among these Vietnam veterans. METHODS A health survey of these 1,499 Vietnam veterans and a group of 1,428 non-Vietnam veterans assigned to chemical operations jobs was conducted using a computer-assisted telephone interview (CATI) system. Exposure to herbicides was assessed by analyzing serum specimens from a sample of 897 veterans for dioxin. Logistic regression analyses were used to estimate the risk of selected medical outcomes associated with herbicide exposure. RESULTS Odds ratios for diabetes, heart disease, hypertension, and chronic respiratory disease were elevated, but not significantly (P>0.05) for those who served in Vietnam. However, they were significantly elevated among those Vietnam veterans who sprayed herbicides: diabetes, odds ratio (OR)=1.50 (95% confidence interval [95%CI]=1.15-1.95); heart disease, OR=1.52 (1.18-1.94); hypertension, OR=1.32 (1.08-1.61); and chronic respiratory condition, OR=1.62 (1.28-2.05). Hepatitis was associated with Vietnam service, but not with herbicide application. CONCLUSIONS Vietnam veterans who were occupationally exposed to herbicide experienced a higher risk of several chronic medical conditions relative to other non-Vietnam veterans. A potential selection bias is of concern. However, there were relatively high participation rates in both the Vietnam and non-Vietnam veteran groups, and the prevalence rates of some of these medical conditions among non-Vietnam veterans were comparable to general populations. Therefore, self-selection factors are considered unlikely to have biased the study results.
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Affiliation(s)
- Han K Kang
- Veterans Health Administration, Department of Veterans Affairs, Washington, District of Columbia 20420, USA.
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Abstract
Environmental factors are considered key determinants of cardiovascular disease. Although lifestyle choices such as smoking, diet, and exercise are viewed as major environmental influences, the contribution of pollutants and environmental chemicals is less clear. Accumulating evidence suggests that exposure to pollutants and chemicals could elevate the risk of cardiovascular disease. Many epidemiological studies report that exposure to fine particles present in ambient air is associated with an increase in cardiovascular mortality. Statistically significant relationships between particulate air pollution and ischemic heart disease, arrhythmias, and heart failure have been reported. Animal studies show that exposure to ambient air particles increases peripheral thrombosis and atherosclerotic lesion formation. Exposures to arsenic, lead, cadmium, pollutant gases, solvents, and pesticides have also been linked to increased incidence of cardiovascular disease. Mechanistically, these effects have been attributed to changes in the synthesis or reactivity of nitric oxide that may be caused by environmental oxidants or increased endogenous production of reactive oxygen species. Additional studies are urgently needed to: identify the contribution of individual pollutants to specific aspects of cardiovascular disease; establish causality; elucidate the underlying physiological and molecular mechanisms; estimate the relative susceptibility of diseased and healthy individuals and that of specific population groups; and determine whether pollutant exposure are risk correlates, that is, whether they influence major risk factors, such as hypertension, cholesterol, or diabetes, or whether they contribute to the absolute risk of heart disease. Collectively, these investigations could contribute to the emergent field of environmental cardiology.
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Affiliation(s)
- Aruni Bhatnagar
- Institute of Molecular Cardiology, Division of Cardiology, Department of Medicine, University of Louisville, Louisville, KY 40202, USA.
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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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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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Reichard JF, Dalton TP, Shertzer HG, Puga A. Induction of oxidative stress responses by dioxin and other ligands of the aryl hydrocarbon receptor. Dose Response 2006; 3:306-31. [PMID: 18648615 DOI: 10.2203/dose-response.003.03.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
TCDD and other polyhalogenated aromatic hydrocarbon ligands of the aryl hydrocarbon receptor (AHR) have been classically considered as non-genotoxic compounds because they fail to be directly mutagenic in either bacteria or most in vitro assay systems. They do so in spite of having repeatedly been linked to oxidative stress and to mutagenic and carcinogenic outcomes. Oxidative stress, on the other hand, has been used as a marker for the toxicity of dioxin and its congeners. We have focused this review on the connection between oxidative stress induction and the toxic effects of fetal and adult dioxin exposure, with emphasis on the large species difference in sensitivity to this agent. We examine the roles that the dioxin-inducible cytochromes P450s play in the cellular and toxicological consequences of dioxin exposure with emphasis on oxidative stress involvement. Many components of the health consequences resulting from dioxin exposure may be attributable to epigenetic mechanisms arising from prolonged reactive oxygen generation.
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Affiliation(s)
- John F Reichard
- Center for Environmental Genetics and Department of Environmental Health, University of Cincinnati Medical Center, Cincinnati, OH 45267, USA
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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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Shaban Z, El-Shazly S, Abdelhady S, Fattouh I, Muzandu K, Ishizuka M, Kimura K, Kazusaka A, Fujita S. Down regulation of hepatic PPARalpha function by AhR ligand. J Vet Med Sci 2005; 66:1377-86. [PMID: 15585952 DOI: 10.1292/jvms.66.1377] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates a spectrum of toxic and biological effects of 2,3,7,8-tetrachloro dibenzo-p-dioxin (TCDD) and related compounds. Peroxisome proliferator activated receptor alpha (PPARalpha) is a nuclear receptor involved in the maintenance of lipid and glucose homeostasis. In this study we hypothesized that one of the possible mechanisms for the effect of TCDD and its related chemicals on fat metabolism could be through down regulation of PPARalpha functions. We treated Wistar rats with an AhR ligand, Sudan III (S.III), and/or PPARalpha ligand, Clofibric Acid (CA), for 3 days. We analysed the expression of one of the PPARalpha-target gene products, CYP4A protein and its mRNA. We also tested HepG2 cells with the afore-mentioned treatments and evaluated their effects on PPARalpha and RXRalpha protein. Treatment of Wistar rats with S.III was found to down regulates CYP4A protein expression and reduced its induction with CA. It also decreased mRNA expressions of CYP4A1, CYP4A2, CYP4A3 and PPARalpha. In HepG2 cells, PPARalpha and RXRalpha protein expression was decreased by S.III treatment in a dose dependent manner. Our results suggest that AhR has an inhibitory effect on PPARalpha function and a new pathway by which AhR ligands could disturb lipid metabolism.
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Affiliation(s)
- Zein Shaban
- Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Japan
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