Background: Exercise-induced bronchoconstriction (EIB) is related to airway inflammation. We aimed to study the association between inflammatory plasma proteins and post-exercise airway responses.

Methods: Using an exploratory approach, we investigated 70 inflammation-linked proteins in relation to airway responses after a dry-air exercise challenge in a population-based cohort of randomly selected adolescents (N=146, age 14). Changes in forced expiratory volume in one second (?FEV1) and respiratory resistance at 5 Hz (?R5) were assessed. EIB was defined as a decrease in FEV1 ?10% or an increase in R5 ?25% from baseline.

Results: EIB by ?FEV1 or ?R5 was found in 48 and 60 participants, respectively; 25 were EIB-positive by both methods. ?FEV1 and ?R5 were used as continuous variables as outcomes in multiple linear regression models adjusted for sex and overweight (BMI >85th percentile). Fibroblast growth factor 21 was negatively associated, and lymphotoxin alpha and neutrophin-3 were positively associated with ?FEV1. CC motif chemokine ligand 19 was negatively associated with ?R5, whereas positive associations were found for interleukin-15 receptor alpha, fibroblast growth factor 19 and interleukin-10 receptor beta. After correction for multiple testing with the false discovery rate set at 0.05, these associations became non-significant.

Conclusion: This exploratory study indicates that different plasma proteins are associated with post-exercise airway responses measured by spirometry or oscillometry. Several of the proteins have previously been linked to airway inflammation and hyperresponsiveness but further investigations in larger cohorts are warranted.