Introduction: The fraction of exhaled nitric oxide (FeNO) and blood eosinophils, markers of local and systemic eosinophilic inflammation, respectively, are increased in asthmatic patients. Little is known concerning the relationship between the FeNO levels and blood eosinophils in asthmatics.
Methods: Twenty severe asthmatics with persistent FeNO elevation (≥40 ppb) and blood eosinophilia (≥3%) despite maintenance therapy including high-daily-dose inhaled corticosteroids were analyzed. We investigated the response of FeNO and blood eosinophils to systemic corticosteroids treatment and the change in Asthma Control Questionnaire (ACQ) according to differences in the response of FeNO and blood eosinophils to steroid.
Results: The changes in blood eosinophils were not correlated with the changes in FeNO levels by systemic steroid treatment (r = 0.37, P = 0.11). 50% of the subjects showed both ≥20% reductions in FeNO levels and blood eosinophils. There were significant differences in the ACQ score between the steroid response group and poor response group (P < 0.005). The group in which both FeNO and blood eosinophils were suppressed fulfilled the change in score of ≥0.5 on the ACQ.
Conclusions: In the patients with severe asthma, responses to systemic corticosteroids were variable in terms of FeNO and blood eosinophils. It was necessary to suppress both persistent eosinophilia and high FeNO for the improvement of asthma control.
Keywords: Asthma; blood eosinophils; exhaled nitric oxide.
© 2017 The Authors. Immunity, Inflammation and Disease Published by John Wiley & Sons Ltd.