title: Proinflammatory properties of coplanar PCBs: in vitro and in vivo evidence.
abstract: So-called coplanar polychlorinated biphenyls (PCBs), as well as other environmental contaminants that are aryl hydrocarbon receptor (AhR) agonists, may compromise the normal functions of vascular endothelial cells by activating oxidative stress-sensitive signaling pathways and subsequent proinflammatory events critical in the pathology of atherosclerosis and cardiovascular disease. To test this hypothesis, porcine endothelial cells were exposed to PCB 153 and to three coplanar PCBs (PCB 77, PCB 126, or PCB 169). In contrast to PCB 153, which is not a ligand for the Ah receptor (AhR), all coplanar PCBs disrupted endothelial barrier function. All coplanar PCBs increased expression of the CYP1A1 gene, oxidative stress (DCF fluorescence), and the DNA-binding activity of nuclear factor kappaB (NF-kappaB). PCB-induced oxidative stress was concentration-dependent, with PCB 126 exhibiting a maximal response at the lowest concentration (0.5 microM) tested. The increase in NF-kappaB-dependent transcriptional activity was confirmed in endothelial cells by a luciferase reporter gene assay. In contrast to PCB 153, coplanar PCBs that are AhR ligands increased endothelial production of interleukin-6. At 3.4 microM, expression of the adhesion molecule VCAM-1 was most sensitive to PCB 77 and 169. We also provide in vivo evidence, suggesting that binding to the AhR is critical for the proinflammatory properties of PCBs. Twenty hours after a single administration of PCB 77, VCAM-1 expression was increased only in wild-type mice, while mice lacking the AhR gene showed no increased staining for VCAM-1. These data provide evidence that coplanar PCBs, agonists for the AhR, and inducers of cytochrome P450 1A1, produce oxidative stress and an inflammatory response in vascular endothelial cells. An intact AhR may be necessary for the observed PCB-induced responses. These findings suggest that activation of the AhR can be an underlying mechanism of atherosclerosis mediated by certain environmental contaminants.
authors.affiliation: Cell Nutrition Group, Department of Animal Sciences, University of Kentucky, Lexington 40506-0054, USA. bhennig@uky.edu
authors.forename: Bernhard
authors.initials: B
authors.lastname: Hennig
authors.forename: Purushothaman
authors.initials: P
authors.lastname: Meerarani
authors.forename: Rabih
authors.initials: R
authors.lastname: Slim
authors.forename: Michal
authors.initials: M
authors.lastname: Toborek
authors.forename: Alan
authors.initials: A
authors.lastname: Daugherty
authors.forename: Allen E
authors.initials: AE
authors.lastname: Silverstone
authors.forename: Larry W
authors.initials: LW
authors.lastname: Robertson
mesh_terms: D000818:Animals; D001161:Arteriosclerosis / Q000139:chemically induced / Q000473:pathology; D015824:Blood-Air Barrier / Q000187:drug effects; D002467:Cell Nucleus / Q000737:chemistry; D002478:Cells, Cultured; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism; D004586:Electrophoresis; D004730:Endothelium, Vascular / Q000737:chemistry / Q000187:drug effects; D004785:Environmental Pollutants / Q000633:toxicity*; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007249:Inflammation / Q000139:chemically induced* / Q000473:pathology; D015850:Interleukin-6 / Q000096:biosynthesis; D008156:Luciferases / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D016328:NF-kappa B / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D011078:Polychlorinated Biphenyls / Q000737:chemistry / Q000633:toxicity*; D018336:Receptors, Aryl Hydrocarbon / Q000819:agonists / Q000172:deficiency; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013329:Structure-Activity Relationship; D013552:Swine
chemical_list: D004785:Environmental Pollutants; D015850:Interleukin-6; D016328:NF-kappa B; D018336:Receptors, Aryl Hydrocarbon; D011078:Polychlorinated Biphenyls; D008156:Luciferases; D019363:Cytochrome P-450 CYP1A1