Exhaled breath condensate thymic stromal lymphopoietin, OX40 ligand, eotaxin, and interleukin-23 in children with atopic dermatitis and persistent wheeze

Background: Atopic dermatitis is a chronic inflammatory condition. It is estimated that 60% of children with severe atopic dermatitis will go on to develop asthma. This study aimed to assess the presence and extent of early airway inflammation in infants with atopic dermatitis. Methods: A total of 73 infants aged <36 months were included in the study, which comprised a group with atopic dermatitis (n = 30), a group with persistent wheezing (n = 22), and a control group of healthy infants (n = 21). The subjects who exhibited persistent wheezing were selected according to the criteria set forth in the Asthma Predictive Index. Exhaled breath condensates (EBC) were collected via the R-tube method. The levels of thymic stromal lymphopoietin (TSLP), OX40 ligand (OX40L), eotaxin, and interleukin-23 (IL-23) in EBCs were determined by using enzyme-linked immunosorbent assay (ELISA). Results: No statistically significant difference was observed in the levels of TSLP and OX40L in EBC among the groups. Eotaxin showed a directionally higher level in the persistent wheezing group; the difference was attenuated after age adjustment and Bonferroni correction but persisted in the 12-30-month sensitivity analysis (persistent wheezing group versus controls, p = 0.011, Bonferroni adjusted). The atopic dermatitis and persistent wheezing groups had lower EBC IL-23 levels than did the controls (age-adjusted analyses, p < 0.001). Conclusion: This study is among the first to quantify TSLP, OX40L, eotaxin, and IL-23 in EBCs from infants with atopic dermatitis, those with persistent wheezing, and healthy controls. Eotaxin levels were directionally higher in the persistent wheezing group than in the controls; however, this difference did not remain statistically significant after age adjustment and Bonferroni correction, and should be interpreted as suggestive rather than confirmatory of eosinophil-associated airway inflammation. In a 12-30-month sensitivity analysis, the persistent wheezing group had a higher natural log-transformed eotaxin concentration than did the controls (p = 0.011, Bonferroni adjusted), which supports this signal within a narrower age window. A lower EBC IL-23 level is biologically intriguing but should be interpreted cautiously given residual confounding and EBC variability.