title: Repeated nitrogen dioxide exposures and eosinophilic airway inflammation in asthmatics: a randomized crossover study.
abstract: BACKGROUND
  Nitrogen dioxide (NO2), a ubiquitous atmospheric pollutant, may enhance the asthmatic response to allergens through eosinophilic activation in the airways. However, the effect of NO2 on inflammation without allergen exposure is poorly studied.
  
  
  OBJECTIVE
  We investigated whether repeated peaks of NO2, at various realistic concentrations, induce changes in airway inflammation in asthmatics.
  
  
  METHODS
  Nineteen nonsmokers with asthma were exposed at rest in a double-blind, crossover study, in randomized order, to 200 ppb NO2, 600 ppb NO2, or clean air once for 30 min on day 1 and twice for 30 min on day 2. The three series of exposures were separated by 2 weeks. The inflammatory response in sputum was measured 6 hr (day 1), 32 hr (day 2), and 48 hr (day 3) after the first exposure, and compared with baseline values measured twice 10-30 days before the first exposure.
  
  
  RESULTS
  Compared with baseline measurements, the percentage of eosinophils in sputum increased by 57% after exposure to 600 ppb NO2 (p = 0.003) but did not change significantly after exposure to 200 ppb. The slope of the association between the percentage of eosinophils and NO2 exposure level was significant (p = 0.04). Eosinophil cationic protein in sputum was highly correlated with eosinophil count and increased significantly after exposure to 600 ppb NO2 (p = 0.001). Lung function, which was assessed daily, was not affected by NO2 exposure.
  
  
  CONCLUSIONS
  We observed that repeated peak exposures of NO2 performed without allergen exposure were associated with airway eosinophilic inflammation in asthmatics in a dose-related manner.
authors.affiliation: Service des Etudes Médicales (SEM), EDF, Levallois-Perret, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Ezratty
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Guillossou
authors.forename: Catherine
authors.initials: C
authors.lastname: Neukirch
authors.forename: Monique
authors.initials: M
authors.lastname: Dehoux
authors.forename: Serge
authors.initials: S
authors.lastname: Koscielny
authors.forename: Marcel
authors.initials: M
authors.lastname: Bonay
authors.forename: Pierre-André
authors.initials: PA
authors.lastname: Cabanes
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Samet
authors.forename: Patrick
authors.initials: P
authors.lastname: Mure
authors.forename: Luc
authors.initials: L
authors.lastname: Ropert
authors.forename: Sandra
authors.initials: S
authors.lastname: Tokarek
authors.forename: Jacques
authors.initials: J
authors.lastname: Lambrozo
authors.forename: Michel
authors.initials: M
authors.lastname: Aubier
mesh_terms: D000328:Adult; D000485:Allergens / Q000276:immunology*; D001249:Asthma / Q000276:immunology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004804:Eosinophils / Q000276:immunology*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007249:Inflammation / Q000139:chemically induced*; D008297:Male; D009585:Nitrogen Dioxide / Q000633:toxicity*; D055815:Young Adult
chemical_list: D000485:Allergens; D009585:Nitrogen Dioxide
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