An Antiinflammatory Effect of Salmeterol, a Long-acting β2 Agonist, Assessed in Airway Biopsies and Bronchoalveolar Lavage in Asthma

Abstract

The addition of long-acting β₂ agonists to inhaled corticosteroid (ICS) therapy in symptomatic patients with asthma improves clinical status more than increasing the dose of ICS. It has been suggested that these benefits could be at the cost of an increase in airway inflammation, but few histopathological studies have been performed in the relevant group. In a double-blind, parallel-group, placebo-controlled study, we randomly assigned 50 symptomatic patients with asthma who were receiving ICS (range, 100 –500 μ g/d) to 12 wk of supplementary treatment with salmeterol (50 μ g twice daily) or fluticasone (100 μ g twice daily) or placebo. Bronchial biopsies and BAL were obtained from 45 patients before and after treatment and analyzed. After treatment with salmeterol there was no deterioration of airway inflammation as assessed by mast cells, lymphocytes, or macrophages in BAL or biopsies, but rather a significant fall in EG1-positive eosinophils in the lamina propria (from a median 18.3 to 7.6 cells/mm, p = 0.01), which was not seen after treatment with fluticasone. The only cellular effect of added fluticasone was a decrease in BAL lymphocyte activation. There was a concurrent improvement in clinical status, more marked with salmeterol than with increased ICS. Thus, adding salmeterol to ICS is not associated with increased “allergic” airway inflammation, but conversely with a complementary antieosinophil effect. Li X, Ward C, Thien F, Bish R, Bamford T, Bao X-H, Bailey M, Wilson JW, Walters EH. An antiinflammatory effect of salmeterol, a long-acting β₂ agonist, assessed in airway biopsies and bronchoalveolar lavage in asthma.