Allergy Asthma Immunol Res. 2019 May;11(3):394-405. English.
Original Article 
Open Access
Youngsoo Lee,1 Ji-Ho Lee,2 Eun-Mi Yang,1 EunMi Kwon,3 Chang-Gyu Jung,4 Su-Chin Kim,1 Youngwoo Choi,1 You Sook Cho,5 Chang-Keun Kim,3 and Hae-Sim Park1
1 Department of Allergy and Clinical Immunology, Ajou University School of Medicine, Suwon, Korea.
2 Department of Pulmonology and Allergy, Yonsei University Wonju College of Medicine, Wonju, Korea.
3 Asthma and Allergy Center, Department of Pediatrics, Inje University Sanggye Paik Hospital, Seoul, Korea.
4 Department of Allergy, Keimyung University School of Medicine, Daegu, Korea.
5 Department of Allergy and Clinical Immunology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Abstract
Purpose
Eosinophilic inflammation is a key component of severe asthma (SA). However, there has been no reliable serum biomarker for the eosinophilic inflammation of SA. We hypothesized that serum eosinophil-derived neurotoxin (EDN) could predict the eosinophilic inflammation of SA in adult asthmatics.
Methods
Severe asthmatics (n = 235), nonsevere asthmatics (n = 898), and healthy controls (n = 125) were enrolled from Ajou University Hospital, South Korea. The serum levels of EDN and periostin were measured by enzyme-linked immunosorbent assay and compared between severe and nonsevere asthmatics. Their associations with total eosinophil count (TEC) and clinical parameters were evaluated; clinical validation of the K-EDN kit for the measurement of serum EDN was evaluated.
Results
Severe asthmatics were older and had longer disease duration with significantly lower levels of forced expiratory volume in 1 second and methacholine PC20 than nonsevere asthmatics. Significant differences were found in TEC or sputum eosinophil count (%) between the groups. The serum levels of EDN and periostin were significantly higher in severe asthmatics than in nonsevere asthmatics and in healthy controls (all P < 0.05). Although significant correlations were found between serum EDN levels measured by the 2 kits (ρ = 0.545, P < 0.0001), higher correlation coefficients between serum EDN levels measured by the K-EDN kit and TEC were higher (ρ = 0.358, P < 0.0001) than those between serum EDN levels measured by the MBL kit and TEC (ρ = 0.319, P < 0.0001) or serum periostin level (ρ = 0.222, P < 0.0001). Multivariate regression analysis demonstrated that serum EDN levels measured by the K-EDN kit predicted the phenotype of SA (P = 0.003), while 2 other biomarkers did not.
Conclusions
The serum EDN level may be a useful biomarker for assessing asthma severity in adult asthmatics.