title: Pathological features and inhaled corticosteroid response of eosinophilic and non-eosinophilic asthma.
abstract: BACKGROUND
  Non-eosinophilic asthma is a potentially important clinicopathological phenotype since there is evidence that it responds poorly to inhaled corticosteroid therapy. However, little is known about the underlying airway immunopathology and there are no data from placebo-controlled studies examining the effect of inhaled corticosteroids.
  
  
  METHODS
  Airway immunopathology was investigated using induced sputum, bronchial biopsies, bronchial wash and bronchoalveolar lavage in 12 patients with symptomatic eosinophilic asthma, 11 patients with non-eosinophilic asthma and 10 healthy controls. The patients with non-eosinophilic asthma and 6 different patients with eosinophilic asthma entered a randomised, double-blind, placebo-controlled crossover study in which the effects of inhaled mometasone 400 microg once daily for 8 weeks on airway responsiveness and asthma quality of life were investigated.
  
  
  RESULTS
  Patients with non-eosinophilic asthma had absence of eosinophils in the mucosa (median 4.4 cells/mm(2) vs 23 cells/mm(2) in eosinophilic asthma and 0 cells/mm(2) in normal controls; p = 0.03) and normal subepithelial layer thickness (5.8 microm vs 10.3 microm in eosinophilic asthma and 5.1 microm in controls, p = 0.002). Non-eosinophilic and eosinophilic asthma groups had increased mast cell numbers in the airway smooth muscle compared with normal controls (9 vs 8 vs 0 cells/mm(2), p = 0.016). Compared with placebo, 8 weeks of treatment with inhaled mometasone led to less improvement in methacholine PC(20) (0.5 vs 5.5 doubling concentrations, 95% CI of difference 1.1 to 9.1; p = 0.018) and asthma quality of life (0.2 vs 1.0 points, 95% CI of difference 0.27 to 1.43; p = 0.008).
  
  
  CONCLUSIONS
  Non-eosinophilic asthma represents a pathologically distinct disease phenotype which is characterised by the absence of airway eosinophilia, normal subepithelial layer thickness and a poor short-term response to treatment with inhaled corticosteroids.
authors.affiliation: Institute for Lung Health, Glenfield Hospital, Leicester LE3 9QP, UK.
authors.forename: Mike
authors.initials: M
authors.lastname: Berry
authors.forename: Angela
authors.initials: A
authors.lastname: Morgan
authors.forename: Dominick E
authors.initials: DE
authors.lastname: Shaw
authors.forename: Deborah
authors.initials: D
authors.lastname: Parker
authors.forename: Ruth
authors.initials: R
authors.lastname: Green
authors.forename: Christopher
authors.initials: C
authors.lastname: Brightling
authors.forename: Peter
authors.initials: P
authors.lastname: Bradding
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Wardlaw
authors.forename: Ian D
authors.initials: ID
authors.lastname: Pavord
mesh_terms: D000305:Adrenal Cortex Hormones / Q000008:administration & dosage*; D000328:Adult; D000368:Aged; D001249:Asthma / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D001706:Biopsy; D001980:Bronchi; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002908:Chronic Disease; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008168:Lung / Q000473:pathology*; D008875:Middle Aged; D011657:Pulmonary Eosinophilia / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D014797:Vital Capacity / Q000502:physiology
chemical_list: D000305:Adrenal Cortex Hormones