Chem. Res. Toxicol. 2006, 19, 521-530
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Exposure to Wear Particles Generated from Studded Tires and Pavement Induces Inflammatory Cytokine Release from Human Macrophages John Lindbom,† Mats Gustafsson,‡ Go¨ran Blomqvist,‡ Andreas Dahl,§ Anders Gudmundsson,§ Erik Swietlicki,| and Anders G. Ljungman*,† DiVision of Occupational and EnVironmental Medicine, Department of Molecular and Clinical Medicine, Faculty of Health Sciences, Linko¨ping UniVersity, SE-581 85 Linko¨ping, Sweden, Swedish National Road and Transport Research Institute (VTI), SE-581 95 Linko¨ping, Sweden, and DiVisions of Ergonomics and Aerosol Technology and Nuclear Physics, Lund UniVersity, P.O. Box 118, SE-221 00 Lund, Sweden ReceiVed NoVember 8, 2005
Health risks associated with exposure to airborne particulate matter (PM) have been shown epidemiologically as well as experimentally, pointing to both respiratory and cardiovascular effects. Lately, wear particles generated from traffic have been recognized to be a major contributing source to the overall particle load, especially in the Nordic countries were studded tires are used. In this work, we investigated the inflammatory effect of PM10 generated from the wear of studded tires on two different types of pavement. As comparison, we also investigated PM10 from a traffic-intensive street, a subway station, and diesel exhaust particles (DEP). Human monocyte-derived macrophages, nasal epithelial cells (RPMI 2650), and bronchial epithelial cells (BEAS-2B) were exposed to the different types of particles, and the secretion of IL-6, IL-8, IL-10, and TNF-R into the culture medium was measured. The results show a significant release of cytokines from macrophages after exposure for all types of particles. When particles generated from asphalt/granite pavement were compared to asphalt/quartzite pavement, the granite pavement had a significantly higher capacity to induce the release of cytokines. The granite pavement particles induced cytokine release at the same magnitude as the street particles did, which was higher than what particles from both a subway station and DEP did. Exposure of epithelial cells to PM10 resulted in a significant increase of TNF-R secreted from BEAS-2B cells for all types of particles used (DEP was not tested), and the highest levels were induced by subway particles. None of the particle types were able to evoke detectable cytokine release from RPMI 2650 cells. The results indicate that PM10 generated by the wear of studded tires on the street surface is a large contributor to the cytokine-releasing ability of particles in traffic-intensive areas and that the type of pavement used is important for the level of this contribution. Furthermore, the airway inflammatory potential of wear particles from tires and pavement might be of a greater magnitude than that of DEP. Introduction The effect of particulate matter (PM) to exacerbate or induce respiratory and cardiovascular diseases has been clearly stated by epidemiological studies (1-5). Laboratory investigations, using animals or human cells, have also indicated the possible role of different fractions and types of PM in these pathophysiological conditions (6-9). There is increasing concern that PM in the environment might have consequences for our health. Not only are people already suffering from respiratory- or cardiac-associated diseases at extra risk, but children are also at a higher risk of having their lung function impaired by airborne PM (3, 10). Because of the proven negative health effects, an EU directive regulating the concentration of PM10 is in force since January 2005. The composition of urban PM consists of particles of different origins and sizes. The fractions * Corresponding author. Division of Occupational and Environmental Medicine, Department of Molecular and Clinical Medicine, Faculty of Health Sciences, Linko¨ping University, SE-581 85 Linko¨ping, Sweden. Tel., +46 13 221481; fax, +46 13 145831; e-mail,
[email protected]. † Linko ¨ ping University. ‡ Swedish National Road and Transport Research Institute. § Division of Ergonomics and Aerosol Technology, Lund University. | Division of Nuclear Physics, Lund University.
are usually divided in three categories; ultrafine (
