Serum periostin levels serve as a biomarker for both eosinophilic airway inflammation and fixed airflow limitation in well-controlled asthmatics.

Objective: Periostin, a matricellular protein, is produced from airway epithelial cells and lung fibroblasts by IL-13. It has been suggested that periostin is involved in allergic inflammation and fibrosis. However, the usefulness of serum periostin measurement in the assessment of airway inflammation and remodeling and management of asthmatic patients is still debated. We aimed to determine whether serum periostin levels reflect eosinophilic airway inflammation and airway remodeling in asthma. Methods: We examined the relationship of serum periostin levels with clinical features, biomarkers for eosinophilic airway inflammation, fraction of exhaled nitric oxide (FeNO) levels and blood eosinophil counts, and pulmonary functions in 235 well-controlled asthmatic patients on inhaled corticosteroids (ICS) treatment. Results: Serum periostin levels were positively correlated with blood eosinophil counts (%) and age (r = 0.36 and 0.23, respectively), and were negatively correlated with body weight and FEV1/FVC (%) (r = -0.24 and - 0.23, respectively) in well-controlled asthmatic patients on ICS treatment (daily dose of 453 mu g equivalent to fluticasone propionate). Blood eosinophil counts and serum periostin levels were similarly associated with increased FeNO levels (>= 40 ppb) in the asthmatics. Serum periostin levels were better associated with fixed airflow limitation (FEV1/FVC ratio <70%) than FeNO levels, blood eosinophil counts or total IgE levels in the asthmatics. Multivariate analysis showed that fixed airflow limitation was significantly associated with high serum periostin levels (>= 97 ng/ml) (Odds ratio 3.2). Conclusions: Serum periostin levels serve as a biomarker for both eosinophilic airway inflammation and fixed airflow limitation in well-controlled asthmatics on ICS treatment.