Effects of oral prednisone on sputum eosinophils and cytokines in patients with severe refractory asthma

Abstract

Background: Severe asthma occurs in a heterogeneous group of patients in whom symptoms and airway inflammation persist despite maximal antiasthma treatment.

Objective: To verify whether a short-term course of oral steroids would modify sputum inflammatory cytokine and sputum eosinophil concentrations and whether this effect is related to the presence of sputum eosinophilia.

Methods: In 59 patients with severe refractory asthma, we measured pulmonary function and inflammatory markers in hypertonic saline-induced sputum before and after 2 weeks of treatment with 0.5 mg/kg of oral prednisone (n = 39) or placebo (n = 20) daily. Selected sputum portions were assayed for total and differential cell counts and supernatant interleukin (IL) 5 and IL-8 concentrations.

Results: At baseline, no statistical differences were found among placebo- and prednisone-treated patients in terms of sputum inflammatory cell percentages and IL-5 and IL-8 concentrations. After treatment, forced expiratory volume in 1 second significantly increased and sputum eosinophil percentages and IL-5 and IL-8 concentrations significantly decreased in the prednisone group, whereas no changes were observed in the placebo group. The positive effect of prednisone treatment was observed only in patients with baseline sputum eosinophilia, whereas in noneosinophilic patients with severe asthma prednisone induced only a significant decrease of sputum IL-8.

Conclusions: Additional high-dose oral corticosteroids improve pulmonary function and reduce not only sputum eosinophil but also sputum proinflammatory cytokine concentrations in patients with severe refractory asthma.