Document Detail

Induction of manganese superoxide dismutase gene expression in bronchoepithelial cells after rockwool exposure.
MedLine Citation:
PMID:  9638637     Owner:  NLM     Status:  MEDLINE    
Superoxide dismutases play an important protective role in the lung defense against the pro-oxidative effect of fibrous dusts (e.g. crocidolite fibers). Particularly crocidolite, but also other asbestos fibers, are known to induce cellular antioxidant defense. Although rockwool, a man-made fiber made from rock, is used widely for insulation purposes, its effects on the superoxide dismutases in bronchoepithelial cells have not been investigated. Thus, the purpose of this study was to determine whether human bronchoepithelial cells (BEAS 2B) respond to rockwool fibers (115-4 experimental rockwool fiber) by induction of MnSOD mRNA and an increase of MnSOD activity levels. The results were compared with BEAS 2B cells exposed to silica (alpha-quartz: DQ12; SiO2) and UICC (Union Internationale Contre le Cancer) crocidolite (concentrations of all dusts: 0, 2, 5, 10, 25, 50 micrograms/cm2 = 0, 2.4, 6, 12, 30, 60 micrograms/ml; 24-h exposure) as control fibers. Scanning electron microscopy confirmed close dust cell contact under all experimental settings. Very low MnSOD mRNA baseline levels rose significantly (p < 0.001) in BEAS 2B cells exposed to all three dusts at 2 micrograms/cm2. However, at > 25 micrograms/cm2 MnSOD mRNA levels in silica- and crocidolite- but not in rockwool-exposed cells decreased. Slight (no significance) increases of MnSOD activity were observed which decreased at higher dust (> 5 micrograms/cm2) concentrations. These results suggest that: (1) like crocidolite and silica, rockwool accelerates MnSOD gene expression in bronchoepithelial cells; (2) an increase of MnSOD mRNA levels is not accompanied by MnSOD activity elevation; (3) in contrast to rockwool, high concentrations (> or = 25 micrograms/cm2) of crocidolite and silica reduced MnSOD activity and MnSOD mRNA levels. Because oxidants (H2O2) and crocidolite fibers were shown to reduce SOD activity, lack of active MnSOD protein may be caused by inactivation on a post-translational level. Furthermore, the decline of MnSOD mRNA and MnSOD activity levels coincides with increasing cytotoxicity. In conclusion, rockwool was demonstrated to induce MnSOD gene expression, perhaps because of its pro-oxidative effect in bronchoepithelial cells. In contrast to crocidolite and silica, rockwool fibers are not cytotoxic in this experimental setting.
J Marks-Konczalik; A Gillissen; M Jaworska; S Löseke; B Voss; A Fisseler-Eckhoff; I Schmitz; G Schultze-Werninghaus
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Lung     Volume:  176     ISSN:  0341-2040     ISO Abbreviation:  Lung     Publication Date:  1998  
Date Detail:
Created Date:  1998-09-14     Completed Date:  1998-09-14     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  7701875     Medline TA:  Lung     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  165-80     Citation Subset:  IM    
Department of Internal Medicine, University Hospital Bergmannsheil, Bochum, Germany.
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MeSH Terms
Asbestos, Crocidolite / analysis,  toxicity
Blotting, Northern
Bronchi / drug effects,  enzymology*,  ultrastructure
Cell Line
Epithelial Cells / drug effects,  enzymology*,  ultrastructure
Gene Expression Regulation / drug effects*
In Situ Hybridization
Manganese / metabolism
Microscopy, Electron, Scanning
Mineral Fibers / analysis,  toxicity*
Silicon Dioxide / analysis,  toxicity*
Superoxide Dismutase / biosynthesis*,  genetics*,  metabolism
Reg. No./Substance:
0/Mineral Fibers; 12001-28-4/Asbestos, Crocidolite; 7439-96-5/Manganese; 7631-86-9/Silicon Dioxide; EC Dismutase

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