Characteristics of airway inflammation and bronchodilator reversibility in COPD: a potential guide to treatment

The management of stable patients with COPD depends on the severity of symptoms and airflow limitation. Regarding inflammation, corticosteroids are the only medications that are recommended for use, and only under restricted circumstances. Corticosteroids tend to undertreat or overtreat patients with COPD when only clinical manifestations and the findings of simple spirometry are considered. Accordingly, our aim was to survey the characteristics of airway inflammation in stable COPD patients, and to assess the interrelations among inflammatory cells, inflammatory mediators, bronchodilator reversibility, and pulmonary function. Factors related to airway inflammation and bronchodilator reversibility may be important in the management of stable COPD patients.

A total of 88 stable patients with smoking-related COPD were recruited into the study. All patients were steroid-free, and had been treated with theophylline, oral beta(2)-agonist agents, anticholinergic agents, and possibly mucolytic agents. Bronchodilator tests and sputum induction were performed to evaluate bronchodilator reversibility, and numbers of inflammatory cells and mediators (eg, interleukin [IL]-8, eotaxin, and regulated on activation, normal T cells expressed and secreted [RANTES]).

Thirty-one of 48 patients (64.6%) who had bronchodilator reversibility, and 19 of 40 patients (47.5%) without bronchodilator reversibility had sputum eosinophilia (median, 8.0% and 7.0%, respectively). FEV(1) showed a significant inverse correlation with the number of sputum neutrophils. The correlation coefficient for postbronchodilator FEV(1) vs the percentage of neutrophils in patients with nonreversible COPD was higher than that in those with reversible COPD. The levels of IL-8 were closely associated with the percentage of neutrophils. The sputum concentrations of IL-8 and albumin were significantly higher in patients with nonreversible COPD than in those with reversible COPD. A significant inverse correlation was found between bronchodilator response (ie, DeltaFEV(1) and DeltaFVC) and prebronchodilator FEV(1).

Eosinophilic inflammation may play a substantial role in COPD, while neutrophils and IL-8 may have a great influence on nonreversible obstructive airways. The assessment of airway inflammation and bronchodilator responses can help the selection of specific therapies and the prediction of clinical outcomes for COPD patients.