title: Repeated exposure to low-dose diesel exhaust after allergen challenge exaggerates asthmatic responses in mice.
abstract: BACKGROUND
  In conjunction with allergens, diesel exhaust particles act as an adjuvant to enhance IgE responses, inducing expression of cytokines/chemokines and adhesion molecules, and increasing airway hyper-responsiveness (AHR). As most studies were designed to expose animals to diesel exhaust throughout the periods of both sensitization and allergen challenge, it remains unclear whether diesel exhaust (DE) exposure exaggerates airway responses in asthmatic animals.
  
  
  OBJECTIVE
  To study effects of exposure to low-dose DE on AHR and allergic airway inflammation in asthmatic mice.
  
  
  METHODS
  BALB/c mice were sensitized by intraperitoneal injection of ovalbumin and challenged by intranasal administration with ovalbumin. They were exposed to low-dose DE for 7 h/day, 5 days/week, for up to 12 weeks. AHR to methacholine was evaluated by whole-body plethysmography as well as bronchoalveolar lavage cell analysis and cytokine gene expression in lungs.
  
  
  RESULTS
  Repeated exposure of asthmatic mice to low-dose DE resulted in increased AHR and gene expression of several pro-asthmatic cytokines/chemokines, but these effects rapidly subsided with continued exposure to DE.
  
  
  CONCLUSIONS
  Repeated exposure to low-dose DE after ovalbumin challenge exaggerates allergic responses in mice, but effects are not prolonged with continuous DE exposure.
authors.affiliation: Fourth Department of Internal Medicine, Nippon Medical School, Tokyo, Japan.
authors.forename: Aki
authors.initials: A
authors.lastname: Matsumoto
authors.forename: Kumiko
authors.initials: K
authors.lastname: Hiramatsu
authors.forename: Yingji
authors.initials: Y
authors.lastname: Li
authors.forename: Arata
authors.initials: A
authors.lastname: Azuma
authors.forename: Shoji
authors.initials: S
authors.lastname: Kudoh
authors.forename: Hajime
authors.initials: H
authors.lastname: Takizawa
authors.forename: Isamu
authors.initials: I
authors.lastname: Sugawara
mesh_terms: D000485:Allergens / Q000276:immunology*; D000818:Animals; D001249:Asthma / Q000139:chemically induced / Q000276:immunology / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity / Q000209:etiology / Q000276:immunology*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D018925:Chemokines / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D019570:Inhalation Exposure; D008168:Lung / Q000648:ultrastructure; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin; D012333:RNA, Messenger / Q000378:metabolism*; D001335:Vehicle Emissions / Q000633:toxicity*
chemical_list: D000485:Allergens; D018925:Chemokines; D016207:Cytokines; D012333:RNA, Messenger; D001335:Vehicle Emissions; D010047:Ovalbumin