Abstract
OBJECTIVE: Eosinophil-derived neurotoxin (EDN) has emerged as a potential biomarker in asthma. Allergic bronchopulmonary aspergillosis (ABPA) is a severe complication of asthma. This study aimed to investigate serum EDN levels in ABPA and assess the diagnostic utility of serum EDN in distinguishing ABPA from Aspergillus fumigatus-sensitized asthma (ASA). METHODS: This is a single-center retrospective analysis of data from patients initially diagnosed with ABPA and asthma between 2021 and 2023. Eighteen patients with ABPA, 11 with unsensitized asthma (UA), 10 with ASA, and 18 healthy controls were enrolled. Serum EDN levels were measured by enzyme-linked immunosorbent assay (ELISA). Comparisons among groups were performed using Mann-Whitney U-test with Bonferroni correction for multiple comparisons. Correlations between EDN and clinical parameters were assessed using Spearman rank correlation analysis. Receiver operating characteristic (ROC) curve analysis was used to evaluate diagnostic performance. RESULTS: Serum EDN levels were significantly higher in ABPA patients (median 132.8 ng/mL, IQR: 106.1-256.4) compared to healthy controls (39.7 ng/mL, IQR: 26.6-53.5), UA (59.4 ng/mL, IQR: 48.9-70.1), and ASA (67.6 ng/mL, IQR: 33.3-104.0) after Bonferroni correction (all p < 0.0083). EDN strongly correlated with eosinophil counts (ρ= 0.73, p < 0.01) and A. fumigatus-specific IgE (ρ= 0.70, p < 0.01), and moderately with total IgE (ρ= 0.45, p < 0.05) and bronchiectasis (ρ= 0.40, p < 0.05). ROC analysis showed that EDN (AUC = 0.844, 95% CI: 0.693-0.996) had comparable diagnostic performance to total IgE (AUC = 0.833, 95% CI: 0.668-0.999) in differentiating ABPA from ASA, with sensitivity of 83.3% (95% CI: 0.608 to 0.942) and specificity of 80.0% (95% CI: 0.490 to 0.965) at a cutoff of 96.26 ng/mL. CONCLUSION: EDN levels are significantly elevated in ABPA and correlates with key disease markers, including eosinophil counts, A. fumigatus-specific IgE and bronchiectasis on chest CT. EDN demonstrates diagnostic potential comparable to total IgE in distinguishing ABPA from other asthma phenotypes. These findings suggest EDN may serve as a useful biomarker for ABPA, though validation in larger, multi-center cohorts is warranted.