title: Lung toxicity induced by intratracheal instillation of size-fractionated tire particles.
abstract: Tire particles (TP) represent a significant component of urban air pollution (PM), constituting more than 10% of PM10 mass at urban locations with heavy traffic. The purpose of this study was to evaluate the effects of size-fractionated TP in an animal exposure model frequently used to assess the health effects of air pollutants. Potential pro-inflammatory and toxic effects of TP2.5 (<2.5 microm) and TP10 (<10 microm) were investigated through instillation of suspensions of these materials in BALB/c mice. Bronchoalveolar lavage fluid (BALF) was screened for total protein, lactate dehydrogenase (LDH), alkaline phosphatase (AP), and beta-glucuronidase (B-Gluc) as markers of cytotoxicity; glutathione (GSH) and superoxide dismutase (SOD) as markers of oxidative potential; and tumor necrosis factor-alpha (TNF-alpha), macrophage inflammatory protein-2 (MIP-2), and inflammatory cells as markers of inflammation. Concomitantly, histological analysis of TP-exposed lungs was performed. A single intratracheal instillation of 10 microg/100 microl, 100 microg/100 microl or 200 microg/100 microl was performed, and after 24h mice were euthanized and BALF examined. Inflammatory cellular profiles showed dose-dependent responses after TP10 exposure, while strong cytotoxic effects, including increases in total protein, LDH and AP, were observed to be associated to TP2.5 exposure. Histologically, TP10-treated lungs mainly showed inflammatory tissue infiltration, in contrast to TP2.5-treated lungs, where lysis of the alveolar barrier appeared to be the most characteristic lesion. Our biochemical, cytological, and histological results indicated differential lung toxicity mechanisms elicited by size-fractionated TP, in agreement with other studies performed in in vivo systems that have shown that lung responses to inhaled or instilled particles are affected by particle size. We conclude that lung toxicity induced by TP10 was primarily due to macrophage-mediated inflammatory events, while toxicity induced by TP2.5 appeared to be related more closely to cytotoxicity.
authors.affiliation: Department of Environmental Sciences, POLARIS Research Center, University of Milano-Bicocca, 1 piazza della Scienza, Milan 20126, Italy.
authors.forename: Paride
authors.initials: P
authors.lastname: Mantecca
authors.forename: Giulio
authors.initials: G
authors.lastname: Sancini
authors.forename: Elisa
authors.initials: E
authors.lastname: Moschini
authors.forename: Francesca
authors.initials: F
authors.lastname: Farina
authors.forename: Maurizio
authors.initials: M
authors.lastname: Gualtieri
authors.forename: Annette
authors.initials: A
authors.lastname: Rohr
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Miserocchi
authors.forename: Paola
authors.initials: P
authors.lastname: Palestini
authors.forename: Marina
authors.initials: M
authors.lastname: Camatini
mesh_terms: D000395:Air Pollutants, Occupational / Q000633:toxicity*; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001992:Bronchoalveolar Lavage Fluid; D002452:Cell Count; D002470:Cell Survival / Q000187:drug effects; D016207:Cytokines / Q000378:metabolism; D007442:Intubation, Intratracheal; D008168:Lung / Q000473:pathology; D008171:Lung Diseases / Q000139:chemically induced* / Q000473:pathology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008855:Microscopy, Electron, Scanning; D010084:Oxidation-Reduction; D010316:Particle Size; D052638:Particulate Matter / Q000008:administration & dosage / Q000633:toxicity*; D011014:Pneumonia / Q000139:chemically induced / Q000473:pathology; D012408:Rubber / Q000633:toxicity*
chemical_list: D000395:Air Pollutants, Occupational; D000975:Antioxidants; D016207:Cytokines; D052638:Particulate Matter; D012408:Rubber