title: Cytotoxicity and genotoxicity of urban particulate matter in mammalian cells.
abstract: Ambient air particulate matter (PM)-associated reactive oxygen species (ROS) have been linked to a variety of altered cellular outcomes. In this study, three different PM samples from diesel exhaust particles (DEPs), urban dust standard reference material SRM1649a and air collected in Manchester have been tested for their ability to oxidise DNA in a cell-free assay, to increase intracellular ROS levels and to induce CYP1A1 gene expression in mammalian cells. In addition, the cytotoxicity and genotoxicity of PM were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and alkaline comet assay, respectively. All PM samples catalysed the Fenton reaction in a cell-free assay, but only DEP resulted in the generation of ROS as measured by dichlorodihydrofluorescein diacetate oxidation in mammalian cells. However, there was no evidence that increased ROS was a consequence of polycyclic aromatic hydrocarbon metabolism via CYP1A1 induction as urban dust, the Manchester dust samples but not DEP-induced CYP1A1 expression. Urban dust was more cytotoxic in murine embryonic fibroblasts (MEFs) than the other PM samples and also induced expression of GADD45a in the GreenScreen Human Cell assay without S9 activation suggesting the presence of a direct-acting genotoxicant. Urban dust and DEP produced comparable levels of DNA damage, as assessed by the alkaline comet assay, in MEFs at higher levels than those induced by Manchester PM. In conclusion, results from the cytotoxic and genotoxic assays are not consistent with ROS production being the sole determinant of PM-induced toxicity. This suggests that the organic component can contribute significantly to this toxicity and that further work is required to better characterise the extent to which ROS and organic components contribute to PM-induced toxicity.
authors.affiliation: Centre for Occupational and Environmental Health, Centre for Epidemiology, Institute of Population Health, Faculty of Medical and Human Sciences, The University of Manchester, Ellen Wilkinson Building, Manchester M13 9PL, UK, Gentronix Ltd, BioHub at Alderley Park, Alderley Edge, Macclesfield, Cheshire, SK10 4TG, UK, School of Environment and Life Sciences, University of Salford, Cockcroft Building, Salford M5 4WT, UK.
authors.forename: Audrey F
authors.initials: AF
authors.lastname: Dumax-Vorzet
authors.affiliation: Gentronix Ltd, BioHub at Alderley Park, Alderley Edge, Macclesfield, Cheshire, SK10 4TG, UK.
authors.forename: M
authors.initials: M
authors.lastname: Tate
authors.affiliation: Gentronix Ltd, BioHub at Alderley Park, Alderley Edge, Macclesfield, Cheshire, SK10 4TG, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Walmsley
authors.affiliation: School of Environment and Life Sciences, University of Salford, Cockcroft Building, Salford M5 4WT, UK.
authors.forename: Rhod H
authors.initials: RH
authors.lastname: Elder
authors.affiliation: Centre for Occupational and Environmental Health, Centre for Epidemiology, Institute of Population Health, Faculty of Medical and Human Sciences, The University of Manchester, Ellen Wilkinson Building, Manchester M13 9PL, UK, Gentronix Ltd, BioHub at Alderley Park, Alderley Edge, Macclesfield, Cheshire, SK10 4TG, UK, School of Environment and Life Sciences, University of Salford, Cockcroft Building, Salford M5 4WT, UK a.povey@manchester.ac.uk.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Povey
mesh_terms: D000393:Air Pollutants / Q000633:toxicity*; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics; D002478:Cells, Cultured; D002947:Cities; D020552:Comet Assay; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics / Q000378:metabolism; D003603:Cytotoxins / Q000633:toxicity*; D004247:DNA / Q000187:drug effects; D004249:DNA Damage; D006801:Humans; D050216:Metabolic Detoxication, Phase I; D051379:Mice; D009153:Mutagens / Q000633:toxicity*; D009687:Nuclear Proteins / Q000235:genetics; D052638:Particulate Matter / Q000633:toxicity*; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015854:Up-Regulation; D000097642:GADD45 Proteins
chemical_list: D000393:Air Pollutants; D018797:Cell Cycle Proteins; D019363:Cytochrome P-450 CYP1A1; D003603:Cytotoxins; D004247:DNA; D009153:Mutagens; D009687:Nuclear Proteins; D052638:Particulate Matter; D011084:Polycyclic Aromatic Hydrocarbons; D017382:Reactive Oxygen Species; C439070:GADD45A protein, human; D000097642:GADD45 Proteins