Characteristics of eosinophilic and non-eosinophilic asthma during treatment with inhaled corticosteroids.
Objective: Eosinophilic inflammation in the respiratory tract is a hallmark of bronchial asthma. In naïve cases, the inflammatory profile is associated with disease severity and reactivity to inhaled corticosteroids (ICS). Sustained airway eosinophilia has been reported during ICS treatment. However, how this contributes to asthma control is unclear, nor are the immunologic characteristics of these cases known. This study was performed to determine the answer these questions.
Methods: To compare phenotypes of eosinophilic and non-eosinophilic asthma (EA and NEA, respectively) under ICS treatment, clinical data were obtained from asthmatic subjects (n = 22) and healthy controls (n = 10), and the leukocyte compositions of induced sputum and peripheral blood were determined. T lymphocyte profiles in systemic blood were assessed by flow cytometry.
Results: A higher frequency of emergency room visits was observed in the NEA group, which had a higher neutrophil count relative to the total inflammatory cell population in induced sputum than the EA group (59.5% vs. 36.6%; P < 0.01). The fraction of helper T (Th)17 lymphocytes as well as the ratio of Th17 to regulatory T cells (Treg) in the peripheral blood was higher in the NEA than in the EA group (0.24 vs. 0.13; P < 0.05).
Conclusions: Th17 were more prevalent than Treg cells in the peripheral blood of NEA patients under ICS treatment, corresponding to neutrophil-dominant airway inflammation and a severe asthmatic phenotype. Thus, an imbalance in Th17/Treg may be associated with the pathogenesis of NEA in patients undergoing ICS treatment.
PMID: 25329682 [PubMed - as supplied by publisher]