title: Oxidant generation promotes iron sequestration in BEAS-2B cells exposed to asbestos.
abstract: Lung injury after asbestos exposure is associated with an oxidative stress that is catalyzed by iron in the fiber matrix, complexed to the surface, or both. We tested the hypothesis that the cellular response to asbestos includes the transport and sequestration of this iron through (1) generation of superoxide for ferrireduction, (2) up-regulation of divalent metal transporter-1 (DMT1) for intracellular transport of Fe2+, and (3) increased production of cellular ferritin where the metal is stored in a catalytically less reactive state. BEAS-2B cells with normal and elevated Cu,Zn superoxide dismutase (SOD) expression were employed for in vitro investigations. After exposure of these cells to asbestos, we demonstrated by fluorescence methodology a significantly increased generation of SOD with ferrireductive capacity. Fiber exposure also increased DMT1 protein and mRNA expression in the BEAS-2B cells. Incubation with asbestos elevated cellular iron and ferritin concentrations, and these responses were diminished in cells with an enhanced expression of SOD. Finally, fiber exposure increased supernatant concentrations of interleukin 8, but this inflammatory mediator was actually increased in cells with elevated SOD expression. We conclude that the response of respiratory epithelial cells to asbestos includes oxidant-mediated mechanisms to sequester catalytically active iron associated with the fiber.
authors.affiliation: Center for Environmental Medicine, Asthma, and Lung Biology, University of North Carolina, Chapel Hill, USA.
authors.forename: Xinchao
authors.initials: X
authors.lastname: Wang
authors.forename: Yiming
authors.initials: Y
authors.lastname: Wu
authors.forename: Jacqueline G
authors.initials: JG
authors.lastname: Stonehuerner
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Dailey
authors.forename: Judy D
authors.initials: JD
authors.lastname: Richards
authors.forename: Ilona
authors.initials: I
authors.lastname: Jaspers
authors.forename: Claude A
authors.initials: CA
authors.lastname: Piantadosi
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Ghio
mesh_terms: D017638:Asbestos, Crocidolite / Q000633:toxicity*; D027682:Cation Transport Proteins / Q000378:metabolism; D002461:Cell Line, Transformed; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005293:Ferritins / Q000378:metabolism; D005609:Free Radicals / Q000378:metabolism; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D019016:Mineral Fibers / Q000633:toxicity*; D016877:Oxidants / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D020545:Respiratory Mucosa / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D000099236:Solute Carrier Family 11, Member 2
chemical_list: D017638:Asbestos, Crocidolite; D027682:Cation Transport Proteins; D005293:Ferritins; D005609:Free Radicals; D016209:Interleukin-8; D007501:Iron; D019016:Mineral Fibers; D016877:Oxidants; D013482:Superoxide Dismutase; D013481:Superoxides; D000099236:Solute Carrier Family 11, Member 2