Association of eosinophil‐derived neurotoxin levels with asthma control status in patients with aspirin‐exacerbated respiratory disease

Background The long‐term goals of asthma treatment are to achieve well control of symptoms and to minimize the future risk of asthma exacerbation. Identifying biomarkers for uncontrolled asthma is important for improving the asthma outcome. This study aimed to investigate the association of the levels of eosinophil‐derived neurotoxin (EDN) with asthma control status in specific asthma phenotype, aspirin‐exacerbated respiratory disease (AERD), and aspirin‐tolerant asthma (ATA). Methods A total of 136 adult asthmatics, including 47 asthmatics with AERD and 89 asthmatics with ATA, were enrolled. Plasma, sputum, and urine were collected at enrollment and the levels of EDN were measured by the K‐EDN ELISA kit. Urinary leukotriene E4 (LTE4) level was measured using liquid chromatography–mass spectrometry (LC‐MS)/MS methods. Asthma control status was evaluated according to the GINA guideline, asthma control test and asthma control questionnaire scores. Results In the total study subjects, sputum levels of EDN as well as of urine and plasma EDN showed significantly higher levels in patients with uncontrolled asthma than in those with well‐controlled or partly‐controlled asthma (ANOVA, p