title: Absence of airway inflammation in a large proportion of adolescents with asthma.
abstract: OBJECTIVE
  Neutrophilic inflammation has been implicated in non-eosinophilic asthma (NEA) in adults, but little is known about NEA in children/adolescents. We assessed clinical and inflammatory characteristics of NEA in adolescent asthma.
  
  
  METHODS
  Airway inflammation, sputum endotoxin, airway hyper-reactivity, atopy and lung function were assessed in 77 adolescents with asthma and 68 without asthma (12-17 years). Asthma was identified on the basis of wheeze and asthma history.
  
  
  RESULTS
  The proportion of NEA (sputum eosinophils <2.5%) was 54%. In this group, atopy, sputum neutrophil, eosinophil, eosinophil cationic protein (ECP), endotoxin, neutrophil elastase and IL-8 levels were not different from those without asthma. In contrast, eosinophilic asthma (EA) was associated with atopy and sputum ECP and IL-8. The majority of NEA had no evidence of inflammation; only 14% had neutrophilia (≥61% neutrophils), compared with 11% of EA, and 15% of those without asthma. Small differences in FEV1 (NS) were found between EA and NEA, but symptom prevalence and severity was not different (63% of EA and 52% of NEA were classified moderate to severe).
  
  
  CONCLUSIONS
  NEA is common in adolescent asthma and has similar clinical characteristics as EA. Neutrophils do not appear to play a role in NEA in adolescents, and underlying mechanisms may not involve airway inflammation.
authors.affiliation: Centre for Public Health Research, Massey University, Wellington, New Zealand.
authors.forename: Collin R
authors.initials: CR
authors.lastname: Brooks
authors.affiliation: Centre for Public Health Research, Massey University, Wellington, New Zealand.
authors.forename: Christine J
authors.initials: CJ
authors.lastname: van Dalen
authors.affiliation: Department of Pediatrics and Adolescent Medicine, Wilhelminenspital, Vienna, Austria.
authors.forename: Angela
authors.initials: A
authors.lastname: Zacharasiewicz
authors.affiliation: Respiratory and Sleep Medicine, School of Medicine and Public Health, University of Newcastle, Newcastle, New South Wales, Australia.|School of Biomedical Science and Pharmacy, Newcastle, New South Wales, Australia.
authors.forename: Jodie L
authors.initials: JL
authors.lastname: Simpson
authors.affiliation: Malaghan Institute of Medical Research, Wellington, New Zealand.
authors.forename: Jacquie L
authors.initials: JL
authors.lastname: Harper
authors.affiliation: Malaghan Institute of Medical Research, Wellington, New Zealand.
authors.forename: Graham
authors.initials: G
authors.lastname: Le Gros
authors.affiliation: Respiratory and Sleep Medicine, School of Medicine and Public Health, University of Newcastle, Newcastle, New South Wales, Australia.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Gibson
authors.affiliation: Centre for Public Health Research, Massey University, Wellington, New Zealand.|Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Neil
authors.initials: N
authors.lastname: Pearce
authors.affiliation: Centre for Public Health Research, Massey University, Wellington, New Zealand.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Douwes
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000378:metabolism / Q000473:pathology*; D002648:Child; D004804:Eosinophils / Q000473:pathology*; D005260:Female; D006801:Humans; D007249:Inflammation / Q000378:metabolism / Q000473:pathology*; D016209:Interleukin-8 / Q000378:metabolism; D007958:Leukocyte Count; D008297:Male; D009504:Neutrophils / Q000473:pathology*; D012137:Respiratory System / Q000378:metabolism / Q000473:pathology*; D013183:Sputum / Q000166:cytology* / Q000378:metabolism
chemical_list: D016209:Interleukin-8
keywords: adolescent; airway inflammation; asthma; eosinophil; induced sputum