title: Exposure to urban PM1 in rats: development of bronchial inflammation and airway hyperresponsiveness.
abstract: BACKGROUND
  Several epidemiological and laboratory studies have evidenced the fact that atmospheric particulate matter (PM) increases the risk of respiratory morbidity. It is well known that the smallest fraction of PM (PM1 - particulate matter having a diameter below 1 μm) penetrates the deepest into the airways. The ratio of the different size fractions in PM is highly variable, but in industrial areas PM1 can be significant. Despite these facts, the health effects of PM1 have been poorly investigated and air quality standards are based on PM10 and PM2.5 (PM having diameters below 10 μm and 2.5 μm, respectively) concentrations. Therefore, this study aimed at determining whether exposure to ambient PM1 at a near alert threshold level for PM10 has respiratory consequences in rats.
  
  
  METHODS
  Rats were either exposed for 6 weeks to 100 μg/m(3) (alert threshold level for PM10 in Hungary) urban submicron aerosol, or were kept in room air. End-expiratory lung volume, airway resistance (Raw) and respiratory tissue mechanics were measured. Respiratory mechanics were measured under baseline conditions and following intravenous methacholine challenges to characterize the development of airway hyperresponsiveness (AH). Bronchoalveolar lavage fluid (BALF) was analyzed and lung histology was performed.
  
  
  RESULTS
  No significant differences were detected in lung volume and mechanical parameters at baseline. However, the exposed rats exhibited significantly greater MCh-induced responses in Raw, demonstrating the progression of AH. The associated bronchial inflammation was evidenced by the accumulation of inflammatory cells in BALF and by lung histology.
  
  
  CONCLUSIONS
  Our findings suggest that exposure to concentrated ambient PM1 (mass concentration at the threshold level for PM10) leads to the development of mild respiratory symptoms in healthy adult rats, which may suggest a need for the reconsideration of threshold limits for airborne PM1.
authors.affiliation: Department: MTA-SZTE Research Group on Photoacoustic Spectroscopy, H-6720, Szeged, Dóm tér 9, Hungary. afilep@titan.physx.u-szeged.hu.|Department of Optics and Quantum Electronics, University of Szeged, H-6720, Szeged, Dóm tér 9, Hungary. afilep@titan.physx.u-szeged.hu.
authors.forename: Ágnes
authors.initials: Á
authors.lastname: Filep
authors.affiliation: Department of Medical Physics and Informatics, University of Szeged, H-6720, Szeged, Korányi fasor 9, Hungary.
authors.forename: Gergely H
authors.initials: GH
authors.lastname: Fodor
authors.affiliation: Institute for Environmental Sciences, University of Szeged, H-6720, Szeged, Dóm tér 9, Hungary.
authors.forename: Fruzsina
authors.initials: F
authors.lastname: Kun-Szabó
authors.affiliation: Department of Pathology, University of Szeged, H-6720, Szeged, Állomás u. 2, Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Tiszlavicz
authors.affiliation: Department of Pathology, University of Szeged, H-6720, Szeged, Állomás u. 2, Hungary.
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Rázga
authors.affiliation: Department of Mineralogy, Geochemistry and Petrology, University of Szeged, H-6722, Szeged, Egyetem u. 2, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Bozsó
authors.affiliation: Department: MTA-SZTE Research Group on Photoacoustic Spectroscopy, H-6720, Szeged, Dóm tér 9, Hungary.|Department of Optics and Quantum Electronics, University of Szeged, H-6720, Szeged, Dóm tér 9, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Bozóki
authors.affiliation: Department: MTA-SZTE Research Group on Photoacoustic Spectroscopy, H-6720, Szeged, Dóm tér 9, Hungary.|Department of Optics and Quantum Electronics, University of Szeged, H-6720, Szeged, Dóm tér 9, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Szabó
authors.affiliation: Department of Medical Physics and Informatics, University of Szeged, H-6720, Szeged, Korányi fasor 9, Hungary.
authors.forename: Ferenc
authors.initials: F
authors.lastname: Peták
mesh_terms: D000818:Animals; D016535:Bronchial Hyperreactivity / Q000139:chemically induced* / Q000473:pathology / Q000503:physiopathology*; D001991:Bronchitis / Q000139:chemically induced* / Q000473:pathology / Q000503:physiopathology*; D002947:Cities; D004781:Environmental Exposure / Q000009:adverse effects*; D006814:Hungary; D008297:Male; D010316:Particle Size; D052638:Particulate Matter / Q000009:adverse effects*; D051381:Rats; D017208:Rats, Wistar; D015656:Respiratory Mechanics / Q000187:drug effects
chemical_list: D052638:Particulate Matter
keywords: Air pollution; Airway hyperresponsiveness; Ambient aerosol; Bronchial inflammation; Lung function