Eosinophil-derived neurotoxin as a biomarker for disease severity and relapse in recalcitrant atopic dermatitis

Background: Eosinophils are encountered in many skin diseases, but the role of eosinophils in atopic dermatitis (AD) remains uncertain.

Objective: To examine the role of serum eosinophil-derived neurotoxin (EDN), eosinophil cationic protein (ECP), and total IgE as a biomarker of disease severity and relapse in severe recalcitrant AD.

Methods: We enrolled 99 patients with AD: 37 with severe recalcitrant AD, 20 with severe AD, and 42 with mild to moderate AD. We examined the difference in serum level of total IgE, ECP, and EDN between the groups and whether any correlation existed between disease severity and ECP or EDN. Lastly, difference in levels of ECP or EDN between those who experienced relapse was examined in the severe recalcitrant group.

Results: Serum levels of total IgE, ECP, and EDN were significantly higher in the severe recalcitrant AD group and severe AD group compared with the mild to moderate AD group. No significant difference was found in serum levels of total IgE, ECP, and EDN between the severe recalcitrant group and severe group. EDN had a significant positive correlation with the SCORing Atopic Dermatitis. No significant correlation was found between EDN and ECP. In the severe recalcitrant group, 29.7% of patients experienced relapse, and EDN was significantly higher in those who experienced relapse. The cutoff value of EDN for predicting relapse was 64.5.

Conclusion: EDN correlated with the disease severity of AD. EDN may predict relapse in severe recalcitrant AD. The EDN serum level could be considered a candidate molecule as a clinical biomarker for evaluating AD disease activity and a predictor of relapse.