Analysis of Th2-specific chemokines in exhaled breath condensate from asthmatic children

Abstract

Rationale Th2-specific chemokines including macrophage-derived chemokine (MDC), thymus and activation-regulated chemokine (TARC) and eotaxin are important mediators for allergic airway inflammation. We investigate whether these chemokines are measurable in exhaled breath condensate and their relation to childhood asthma. Methods Patients aged 7 to 18 years old with physician-diagnosed asthma were eligible. Exhaled breath condensate was collected by disposable collection kits (RTubes, Respiratory Research Inc., Charlottesville, VA, USA) whereas fractional exhaled nitric oxide level (FENO) was measured by chemiluminescence (NOA280i, Sievers Instruments, Boulder, CO, USA). Concentrations of MDC, TARC, and eotaxin in EBC were measured using sandwich enzyme immunoassay. Results Forty-eight children with persistent asthma (PA), 36 children with intermittent asthma (IA) and 18 controls were recruited. MDC and eotaxin were present in EBC from all subjects, whereas TARC could be measured in EBC from 33 (32%) subjects only. The median MDC concentration in EBC was higher in PA (117 pg/ml) as compared to IA (106 pg/ml; p=0.003) and controls (105 pg/ml; p=0.003). Among patients with PA, MDC concentrations in EBC decreased with increasing dose of inhaled corticosteroid, with the median values being 122 pg/ml for low-dose, 117 pg/ml for intermediate-dose and 76 pg/ml for high-dose (p=0.005 for trend). FENO was significantly higher in asthmatics than controls (p<0.0001), but it did not show any correlation with chemokine levels in EBC or the dosage of inhaled corticosteroid. Conclusions Our results suggest that MDC is increased in EBC from children with PA, and MDC concentrations in EBC decreases with increasing dosage of inhaled corticosteroid in these patients.