Targeted metabolomic analysis of exhaled breath condensate before and after bronchial provocation by eucapnic voluntary hyperventilation in adolescents with asthma: an exploratory study.

Abstract

Objective: To analyze endogenous metabolites in exhaled breath condensate before and after eucapnic voluntary hyperventilation (EVH) in adolescents with asthma with and without exercise-induced bronchoconstriction (EIB).

Methods: This was an exploratory study including 44 adolescents with asthma in the 10- to 20-year age bracket. They were divided into two groups: the group of patients with EIB (n = 25) and that of those without (n = 19). EIB was defined as a ≥ 10% reduction in FEV₁ after a six-minute EVH challenge using 5% carbon dioxide. Ventilation was maintained at 21 times the baseline FEV₁. Exhaled breath condensate was collected before EVH and 15-30 min after EVH by using a validated device. Samples were analyzed by proton nuclear magnetic resonance focusing on the region of d1.60-2.00 parts per million. Data were preprocessed by using sum normalization and autoscaling for orthogonal partial least squares discriminant analysis.

Results: All participants completed the protocol without adverse events. The mean reduction in FEV₁ was significantly greater in the group of patients with EIB than in that of those without (-25.13% vs. -4.37%; mean difference, -20.76%; 95% CI, -26.45 to -15.07). In the EIB group, responses were classified as mild (n = 15), moderate (n = 9), or severe (n = 1). Post-EVH orthogonal partial least squares discriminant analysis showed significant separation between pre- and post-EVH metabolic profiles in the group of patients with EIB (p < 0.001) but not in that of those without (p = 0.195). The discriminative response in patients with EIB was associated with a marked increase in acetate signal intensity at 1.76 parts per million.

Conclusions: Adolescents with EIB show a distinct metabolic fingerprint that is significantly associated with ventilatory stress. Acetate emerged as a key metabolic differentiator, suggesting a specific biochemical pathway associated with the exercise response and supporting its potential role in precision phenotyping of EIB.