Eosinophil-derived Neurotoxin Levels in Serum Are Associated with Asthma-Like Symptoms

The aim was to study the association between eosinophil-derived neurotoxin (EDN) and gender, atopy and asthma-like symptoms in the Uppsala cohort of the ECRHS III study. Of the 321 included middle-aged subjects, 83 reported physician-diagnosed asthma. The non-asthmatics were divided into subgroups of rhinitis (n=77) or healthy subjects (n=161). Asthma-like symptoms were self-reported in a standardized questionnaire. Serum EDN was measured using an ImmunoCAP research assay. Atopy was defined as a positive ImmunoCAP Phadiatop test (≥0.35 PAU/l; Thermo Fisher Scientific/Phadia AB, Uppsala, Sweden). Higher serum EDN in the cohort was associated with an asthma diagnosis (median: 29.8 vs. 22.4 µg/l, p<0.001), male gender (26.7 vs. 21.3 µg/l, p<0.05), atopy (27.6 vs. 22.1 µg/l, p<0.05), current wheeze (29.9 vs. 20.6 µg/l, p<0.0001), nightly chest tightness (31.7 vs. 23.2 µg/l, p<0.01), and breathlessness during activity (29.8 vs. 22.3 µg/l, p<0.01), but not with nightly breathlessness (p=0.104). The association between EDN and male gender was found also in the healthy subgroup (25.0 vs. 18.2 µg/l, p<0.05). Higher EDN in relation to current wheeze was found in both subjects without an asthma diagnosis (28.1 vs. 20.3 µg/l, p<0.01), as well as in the healthy subgroup (28.6 vs. 20.1 µg/l, p<0.01). The study shows an association between serum EDN and male gender, atopy and common asthma symptoms, and indicates an underlying eosinophilic inflammation associated with current wheeze in individuals without asthma diagnosis.