Inflammatory Mediators in Induced Sputum and Airway Hyperresponsiveness in Cough Variant Asthma during Long-Term Inhaled Corticosteroid Treatment

Abstract EN

Objective.

This study aimed to investigate improvements in inflammatory mediator levels in induced sputum and airway hyperresponsiveness (AHR) in cough variant asthma (CVA) during long-term inhaled corticosteroid (ICS) treatment.

Patients and Methods.

Patients with CVA (N=35) and classic asthma (N=26) and healthy subjects (N=24) were recruited into this study.

All patients were treated with budesonide (400 μg/day).

Measurement of inflammatory mediators in induced sputum and PD20-FEV1 (the accumulated provocative dose resulting in a 20% decrease in FEV1) in histamine-challenged subjects was performed every three months after the start of medication.

Interleukin- (IL-) 5 and IL-10 were assayed by ELISA, and the percentage of eosinophils was detected with Giemsa stain.

Trends during the follow-up period were analyzed using a general linear model.

Results.

Inflammatory mediator levels in induced sputum and PD20-FEV1 in patients with CVA and classic asthma differed from those in the control group, although no differences were found in the two asthmatic groups.

PD20-FEV1 significantly increased in CVA patients after ICS treatment for 3 months, while classic asthma patients exhibited a delayed change in AHR.

After ICS treatment, levels of IL-5 and IL-10 as well as the percentage of eosinophils in the CVA group were altered at 3 months and 6 months, respectively.

Accordingly, the level of inflammatory mediators in classic asthma changed more slowly.

Conclusion.

CVA has a greater improvement in airway inflammation and airway hyperresponsiveness (AHR) than classic asthma with respect to inhaled corticosteroid (ICS).

Short-term ICS considerably reduces AHR although longer treatment is required for complete control of airway inflammation.