Study objectives: Cigarette smoking is common in
asthmatic patients, and we investigated the impact of cigarette smoking
on airway inflammation in asthma.
Single-center observational study of airway inflammation in asthmatic
and healthy smokers and nonsmokers.
research unit in a university hospital.
participants: Sixty-seven asthmatic and 30 nonasthmatic subjects
classified as smokers or nonsmokers. Asthmatics had chronic, stable
asthma and were not receiving inhaled or oral steroids at the time of
Interventions: We examined induced-sputum
cell counts and levels of interleukin (IL)-8 and eosinophilic cationic
protein (ECP). Bronchial hyperreactivity was assessed using
Measurements and results:
Asthmatic smokers had higher total sputum cell counts than nonsmoking
asthmatics and both smoking and nonsmoking healthy subjects. Smoking
was associated with sputum neutrophilia in both asthmatics and
nonasthmatics (median, 47% and 41%, respectively) compared with
nonsmokers (median, 23% and 22%, respectively), and sputum IL-8 was
increased in smokers compared with nonsmokers, both in subjects with
asthma (median, 945 pg/mL vs 660 pg/mL, respectively) and in healthy
subjects (median, 1,310 pg/mL vs 561 pg/mL, respectively). Sputum
eosinophils and ECP levels were higher in both nonsmoking and smoking
asthmatics than in healthy nonsmokers. In smoking asthmatics, lung
function (FEV1 percent predicted) was negatively related to
both sputum IL-8 (r = − 0.52) and sputum neutrophil
proportion (r = − 0.38), and sputum IL-8 correlated
positively with smoking pack-years (r = 0.57) and
percent neutrophil count (r = 0.51).
Conclusions: In addition to the eosinophilic airway
inflammation observed in patients with asthma, smoking induces
neutrophilic airway inflammation; a relationship is apparent between
smoking history, airway inflammation, and lung function in smoking