Systemic endothelial activation and eosinophilic inflammation in pediatric allergic rhinitis: diagnostic value of endocan and eosinophil-derived neurotoxin

Objective biomarkers that reflect systemic inflammation in pediatric allergic rhinitis to support clinical diagnosis. We aimed to evaluate serum levels of endocan (a marker of endothelial activation) and eosinophil-derived neurotoxin (EDN; reflecting eosinophil degranulation) in children with AR and investigate their diagnostic performance and associations with disease severity and conventional inflammatory markers. In this prospective case-control study, 85 children with AR and 67 healthy controls were enrolled. Serum endocan and EDN were measured via sandwich ELISA. Primary outcomes included group comparisons of biomarker levels and their diagnostic accuracy determined by receiver operating characteristic (ROC) curve analysis. Serum endocan and EDN levels were significantly elevated in children with AR compared to controls (both p < 0.001). Both biomarkers demonstrated high diagnostic performance, with an area under the curve (AUC) of 0.931 for endocan and 0.929 for EDN, showing greater diagnostic accuracy than absolute eosinophil counts (AUC, 0.871). Endocan and EDN showed a strong intercorrelation (r = 0.88, p < 0.001) and significant positive correlations with total IgE and eosinophil counts. However, no significant associations were observed between these biomarkers and disease severity, symptom control scores, or allergen sensitization patterns. CONCLUSIONS: Serum endocan and EDN are significantly elevated in children with AR and demonstrate high diagnostic discrimination in this cohort. These findings suggest that endocan and EDN may serve as promising complementary biomarkers for the objective assessment of allergic inflammation in children, although further multicenter studies are needed to confirm their clinical utility. WHAT'S KNOWN: • Allergic rhinitis (AR) is common in childhood and involves systemic inflammatory pathways; however, objective biomarkers to support diagnosis in pediatric practice remain limited. • Endocan and eosinophil-derived neurotoxin (EDN) reflect endothelial activation and eosinophil degranulation, respectively, and have been studied in other atopic and inflammatory conditions. WHAT IS NEW: • This study concurrently evaluates serum Endocan and EDN in children with AR in a prospective case-control design. • Both biomarkers demonstrated high discriminatory performance (AUC∼ 0.93 in this cohort) and showed greater diagnostic accuracy than absolute eosinophil counts . • Endocan and EDN are largely independent of generalized systemic inflammatory indices (NLR, SII, SIRI), supporting specificity for the endothelial- eosinophilic axis in pediatric AR.