Inflammatory and genotoxic effects of diesel particles in vitro and in vivo

Publication: Research - peer-reviewJournal article – Annual report year: 2004

Without internal affiliation

DOI

  • Author: Dybdahl, Marianne

    National Research Centre for the Working Environment

  • Author: Risom, Lotte

    University of Copenhagen

  • Author: Bornholdt, Jette

    National Research Centre for the Working Environment

  • Author: Autrup, Herman

    Aarhus University

  • Author: Loft, Steffen

    University of Copenhagen

  • Author: Wallin, Håkan

    National Research Centre for the Working Environment

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Recent studies have identified an indirect genotoxicity pathway involving inflammation as one of the mechanisms underlying the carcinogenic effects of air pollution/diesel exhaust particles (DEP). We investigated the short-term effects of DEP on markers of inflammation and genotoxicity in vitro and in vivo. DEP induced an increase in the mRNA level of pro-inflammatory cytokines and a higher level of DNA strand breaks in the human lung epithelial cell line A549 in vitro. For the in vivo study, mice were exposed by inhalation to 20 or 80 mg/m3 DEP either as a single 90-min exposure or as four repeated 90-min exposures (5 or 20 mg/m3) and the effects in broncho-alveolar lavage (BAL) cells and/or lung tissue were characterized. Inhalation of DEP induced a dose-dependent inflammatory response with infiltration of macrophages and neutrophils and elevated gene expression of IL-6 in the lungs of mice. The inflammatory response was accompanied by DNA strand breaks in BAL cells and oxidative DNA damage and increased levels of bulky DNA adducts in lung tissue, the latter indicative of direct genotoxicity. The effect of a large single dose of DEP was more pronounced and sustained on IL-6 expression and oxidative DNA damage in the lung tissue than the effect of the same dose administered over four days, whereas the reverse pattern was seen in BAL cells. Our results suggest that the effects of DEP depend on the rate of delivery of the particle dose. The mutation frequency (MF), after DEP exposure, was determined using the transgenic Muta™Mouse and a similar exposure regimen. No increase was observed in MF in lung tissue 28-days after exposure. In conclusion, short-term exposure to DEP resulted in DNA strand breaks in BAL cells, oxidative DNA damage and DNA adducts in lungs; and suggested that DNA damage in part is a consequence of inflammatory processes. The response was not associated with increased MF, indicating that the host defence mechanisms were sufficient to counteract the adverse effects of inflammation. Thus, there may be thresholds for the inflammation-associated genotoxic effects of DEP inhalation.

Original languageEnglish
JournalMutation Research - Genetic Toxicology and Environmental Mutagenesis
Volume562
Issue number1-2
Pages (from-to)119-131
Number of pages13
ISSN1383-5718
DOIs
StatePublished - 8 Aug 2004
Externally publishedYes
CitationsWeb of Science® Times Cited: 84

    Keywords

  • Cytokines, Diesel exhaust particles, Genotoxicity, Inflammation, Inhalation, Mutations
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