Mechanisms of asthma and allergic inflammationExhaled nitric oxide identifies the persistent eosinophilic phenotype in severe refractory asthma
Section snippets
Study design
This was a cross-sectional study at a single time point looking at the relationship between exhaled NO and bronchoscopic parameters of inflammation.
Subjects
Subjects with asthma of various severities who were referred to National Jewish Medical and Research Center for evaluation were recruited together with healthy control subjects. They underwent history and physical examination, lung function testing (short-acting bronchodilators and long-acting bronchodilators were held for 4 hours and 12 hours,
Subject characteristics
Twenty-four subjects with SRA, 4 subjects with moderate asthma, 11 subjects with mild asthma, and 17 healthy control subjects were studied. This article reports only subjects with both FENO measurement and a bronchoscopy: for EOS+ SRA, 8 of 10 underwent BAL, and 8 of 10 underwent EBBX (different missing subjects); for EOS− SRA, 14 of 14 underwent BAL, and 12 of 14 underwent EBBX. All 14 subjects with mild-moderate asthma and all control subjects underwent both procedures. Eleven of 14 subjects
Discussion
In this study FENO measurement identified the persistent eosinophilic phenotype in subjects with SRA despite therapy with inhaled and systemic steroids. Correspondingly, FENO levels correlated with eosinophilic inflammation in the SRA group but not in the subjects with mild-moderate asthma, probably because of more significant suppression of both eosinophilia and exhaled NO by ICSs. Exhaled NO levels also correlated with tissue lymphocyte and mast cell counts in SRA, with no significant
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Supported by National Heart, Lung, and Blood Institute grant no. HL64087A-400600RR-00051.