Inflammatory mediators in exhaled breath condensate of children with obstructive sleep apnea syndrome

Background: Upper airway inflammation is now recognized in adults with obstructive sleep apnea (OSA) syndrome. However, the role played by eicosanoids such as leukotrienes and prostaglandins is unclear. Objective: To investigate whether eicosanoids are measurable in exhaled breath condensate (EBC), and to determine whether differences in these inflammatory mediators emerge among children with and without sleep-disordered breathing (SDB). Methods: EBC was collected from 50 consecutive snoring children undergoing overnight polysomnography for suspected SDB, and from 12 nonsnoring control subjects. Prostaglandin E₂ (PGE₂), leukotriene B₄ (LTB₄), and cysteinyl leukotrienes (cys-LTs: leukotriene C ₄ [LTC₄]/leukotriene D₄ [LTD ₄]/leukotriene E₄ [LTE₄]) EBC levels were analyzed using enzyme-linked immunosorbent assay. Results: LTB₄ levels were elevated in children with an apnea-hypopnea index (AHI) > 5/h (SDB; 97.6 ± 6.3 pg/mL) compared to children with an AIII < 5/h (mild SDB; 66.4 ± 19.1 pg/mL; p < 0.01) and control subjects (27.8 ± 3.7 pg/mL; p < 0.01). Similarly, cys-LT (LTC₄/LTD ₄/LTE₄) concentrations were also increased in SDB (45.1 ± 10.6 pg/mL in SDB vs 27.6 ± 8.3 pg/mL in mild SDB, and 15.7 ± 7.6 pg/mL in control subjects; p < 0.01). In contrast, PGE ₂ concentrations were similar among the three groups. Conclusions: Inflammatory mediators such as leukotrienes and prostaglandins can be readily quantified in EBC collected from the upper airway of children. Disease severity-dependent increases in leukotriene concentrations (LTB₄ and LTC₄/LTD₄/LTE₄) emerge among children and may serve as a noninvasive tool in the clinical assessment of these children.