Background: Severe asthma is a refractory disease with complex and heterogeneous pathophysiologic mechanisms. Eosinophilic inflammation is considered a key component of severe asthma (SA). However, there has been no reliable biomarker representing the eosinophilic inflammation of SA.
Objective: This study aimed to characterize the clinical features of SA and to evaluate whether serum eosinophil-derived neurotoxin (EDN) level may predict the eosinophilic inflammation of SA in adult asthmatics.
Methods: Severe asthmatics (n = 235) and nonsevere asthmatics (n = 898) were enrolled from Ajou University Hospital, South Korea. Serum levels of EDN and periostin (type 2 inflammatory biomarkers) were measured using ELISA, and their association with clinical parameters was analyzed.
Results: Severe asthmatics were older and had longer disease durations with significantly lower levels of FEV1% pred and methacholine PC20. Total eosinophil count (TEC) and sputum eosinophil count (%) were significantly higher in severe asthmatics than in nonsevere asthmatics. Serum EDN level and serum periostin level were significantly higher in severe asthmatics than in nonsevere asthmatics (P < 0.034 and P < 0.001, respectively). Correlations of serum EDN level to TEC (r = 0.319, P < 0.001) and to serum periostin level (r = 0.302, P < 0.001) were noted in total asthmatics.
Conclusion: These findings suggest that serum EDN level can be a useful biomarker for predicting the phenotype of SA in adult asthmatics.
