Abstract
BackgroundPeriostin levels are associated with airway eosinophilia and are suppressed by corticosteroid treatment in asthma. This study sought to determine the relationship between serum and sputum periostin, airway inflammatory phenotype and asthma control.MethodsAdults with poorly-controlled asthma (n = 83) underwent a clinical assessment, sputum induction and blood sampling. Dispersed sputum was used for a differential cell count and periostin assessment (ELISA). Serum periostin was determined by the Elecsys® immunoassay.ResultsPeriostin levels were significantly higher in serum (median (IQR) of 51.6 (41.8, 62.6) ng/mL) than in sputum (1.1 (0.5, 2.0) ng/mL) (p < 0.001). Serum and sputum periostin were significantly higher in patients with eosinophilic asthma (n = 37) compared with non-eosinophilic asthma. Both serum and sputum periostin levels were significantly associated with proportion of sputum eosinophils (r = 0.422, p < 0.001 and r = 0.364, p = 0.005 respectively) but were not associated with asthma control. In receiver operator characteristic curve analysis, the area under the curve (AUC) for serum periostin (n = 83) was 0.679, p = 0.007. Peripheral blood eosinophils assessed in 67 matched samples, had a numerically greater AUC of 0.820 compared with serum periostin, p = 0.086 for the detection of eosinophilic asthma.ConclusionIn poorly-controlled asthma, sputum and serum periostin levels are significantly related to sputum eosinophil proportions while their ability to predict the presence of eosinophilic asthma is modest.Electronic supplementary materialThe online version of this article (doi:10.1186/s12890-016-0230-4) contains supplementary material, which is available to authorized users.
Highlights
Periostin levels are associated with airway eosinophilia and are suppressed by corticosteroid treatment in asthma
While levels of periostin in induced sputum were lower than those measured in serum, both sputum and serum periostin levels were significantly associated with airway eosinophilia
It is unclear if the lower sputum periostin levels compared to serum are the result of limitations in detecting proteins in sputum supernatant samples processed with sputolysin, differences in the assays utilised in the detection of periostin or a biological difference between the sample types
Summary
Periostin levels are associated with airway eosinophilia and are suppressed by corticosteroid treatment in asthma. We have recently shown that blood eosinophil counts are a suitable surrogate for sputum eosinophil proportion in identifying patients with eosinophilic asthma, being simple and readily available and may provide a suitable asthma management tool [3]. Periostin gene expression is upregulated in a subset of patients in which it was associated with the expression of Th2 cytokines. These patients had higher blood and BAL eosinophil counts and were most responsive to inhaled corticosteroids (ICS) [5]. Periostin is expressed by lung epithelial cells and fibroblasts and invitro experiments show that periostin is secreted
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