Background: Identifying inflammatory phenotypes is relevant in severe uncontrolled asthma. The aim of this study was to identify the different clinical, inflammatory, functional, and molecular phenotypes in patients with severe asthma and to investigate the potential role of sputum periostin as a biomarker of severe asthma phenotypes.
Patients and methods: Sputum induction was performed in 62 patients diagnosed with severe asthma. Skin prick testing, lung function tests, exhaled nitric oxide, hematimetry, and total serum IgE were performed. Periostin was measured in sputum supernatants.
Results: Patients with asthma were phenotyped and 80% had late-onset asthma, 50% had fixed airflow obstruction, and 66% showed a Th2-high phenotype. With respect to inflammatory phenotypes, 71% were eosinophilic and 25% mixed granulocytic. Periostin levels were higher in patients with fixed as compared to variable airflow limitation (69.76 vs 43.84 pg/ml, P < 0.05) and in patients with eosinophilic as compared to mixed granulocytic phenotype (61.58 vs 37.31 pg/ml, P < 0.05). There was an inverse correlation between postbronchodilator FEV1 /FVC and periostin levels (-0.276, P < 0.05).
Conclusion: This study demonstrates the utility of periostin in phenotyping severe asthma. Periostin levels in sputum are associated with persistent airflow limitation in asthma patients with airway eosinophilia despite treatment with high-dose inhaled corticosteroids.
Keywords: asthma biomarkers; asthma phenotypes; induced sputum; periostin; severe asthma.
© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.