Airway immunopathology of asthma with exercise-induced bronchoconstriction.
BACKGROUND
Exercise-induced bronchoconstriction (EIB) is a common cause of symptoms in a subgroup of asthmatic subjects. The pathobiology that makes this group of asthmatic subjects susceptible to bronchoconstriction after a brief period of exercise remains poorly understood.


OBJECTIVE
We sought to determine whether there are differences in lower airway inflammation and production of cytokines and eicosanoids between asthmatic subjects with and without EIB.


METHODS
Two distinct groups of asthmatic subjects based on a priori definitions were identified, one with moderate-to-severe EIB and the other without significant bronchoconstriction after exercise challenge. Both groups met the definition of asthma on the basis of bronchodilator response, bronchial hyperresponsiveness, or both. A comparative immunopathology study was conducted by using induced sputum to identify differences in lower airway inflammation and production of cytokines and eicosanoids.


RESULTS
The groups had similar baseline lung function and bronchodilator response and did not have any asthma exacerbations within the prior year. The concentration of columnar epithelial cells was markedly higher in the group with EIB (1.4 x 10(5) vs 2.9 x 10(4) cells/mL, P=.01). The concentration of eosinophils was higher in the group with EIB (3.6 x 10(4) vs 4.9 x 10(3) cells/mL P=.04). Cysteinyl leukotrienes (CysLTs; 727.7 vs 151.9 pg/mL, P=.01) and the ratio of CysLTs to prostaglandin E(2) (1.85 vs 1.04, P=.002) in the airways were higher in the group with EIB.


CONCLUSIONS
Injury to the airway epithelium, overexpression of CysLTs, relative under production of prostaglandin E(2), and greater airway eosinophilia are distinctive immunopathologic features of asthma with EIB.
Hallstrand
Teal S
TS
Department of Medicine, Division of Pulmonary and Critical Care, University of Washington, Seattle, WA 98195, USA. tealh@u.washington.edu
Moody
Mark W
MW
Aitken
Moira L
ML
Henderson
William R
WR
D000328:Adult; D001250:Asthma, Exercise-Induced / Q000276:immunology* / Q000473:pathology*; D016207:Cytokines / Q000032:analysis / Q000276:immunology; D015777:Eicosanoids / Q000032:analysis / Q000276:immunology; D004804:Eosinophils / Q000276:immunology; D005260:Female; D006801:Humans; D008168:Lung / Q000276:immunology* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D013183:Sputum / Q000737:chemistry / Q000166:cytology / Q000276:immunology
D016207:Cytokines; D015777:Eicosanoids