Elevated exhaled leukotriene B4 in the small airway compartment in children with asthma.

BACKGROUND: Inflammatory processes in the asthmatic lung involve the large and small airway and alveolar sites. Leukotriene B4 (LTB4) is an important disease marker, but its role in inflammation of the small airways in asthma has not been established yet. OBJECTIVE: To distinguish between large and small airway or alveolar LTB4 concentrations in children with asthma using the new technique of fractionated exhaled breath condensate sampling. METHODS: Sixty-eight children (9-17 years old, 33 children with asthma and 35 controls) underwent fractional exhaled nitric oxide (FeNO) measurements, lung function testing, and collection of fractionated exhaled breath condensate using a capnograph-based approach. The LTB4 concentrations in the small airway or alveolar and large airway fractions were correlated to disease status, lung function impairment, and clinical parameters. RESULTS: Children with asthma had significantly higher LTB4 concentrations in the small airway or alveolar fraction than controls (5.58 pg/mL; 95% interquartile range [IQR], 2.0-11.77 pg/mL; vs 2.0 pg/mL; 95% IQR, 2.0-6.2 pg/mL; P = .003). No difference was found between the groups in the large airway fraction. Children with obstructive lung function impairment (forced expiratory volume in 1 second z score <-1.65) had increased small airway or alveolar LTB4 concentrations compared with children without impairment (2.0 pg/mL; 95% IQR, 2.0-9.21 pg/mL; vs 18.32 pg/mL; 95% IQR, 3.7-23.02 pg/mL; P = .04). Children with asthma but without pathologic obstructive lung function still had higher LTB4 concentrations than controls (5.57 pg/mL; 95% IQR, 2.00-10.60 pg/mL; vs 2.00 pg/mL; 95% IQR, 2.00-6.20 pg/mL; P = .01). CONCLUSION: LTB4 is detectable and elevated in the small airway or alveolar fraction of exhaled breath condensate in pediatric asthma. Because of the possibility of detecting elevated levels in patients without lung function impairment in controlled disease, it may be used as a noninvasive marker of small airways disease; however, future long-term studies are needed.

Fractionated breath condensate sampling: H(2)O(2) concentrations of the alveolar fraction may be related to asthma control in children.

BACKGROUND: Asthma is a chronic inflammatory disease of the airways but recent studies have shown that alveoli are also subject to pathophysiological changes. This study was undertaken to compare hydrogen peroxide (H(2)O(2)) concentrations in different parts of the lung using a new technique of fractioned breath condensate sampling. METHODS: In 52 children (9-17 years, 32 asthmatic patients, 20 controls) measurements of exhaled nitric oxide (FE(NO)), lung function, H(2)O(2) in exhaled breath condensate (EBC) and the asthma control test (ACT) were performed. Exhaled breath condensate was collected in two different fractions, representing mainly either the airways or the alveoli. H(2)O(2) was analysed in the airway and alveolar fractions and compared to clinical parameters. RESULTS: The exhaled H(2)O(2) concentration was significantly higher in the airway fraction than in the alveolar fraction comparing each single pair (p = 0.003, 0.032 and 0.040 for the whole study group, the asthmatic group and the control group, respectively). Asthma control, measured by the asthma control test (ACT), correlated significantly with the H(2)O(2) concentrations in the alveolar fraction (r = 0.606, p = 0.004) but not with those in the airway fraction in the group of children above 12 years. FE(NO) values and lung function parameters did not correlate to the H(2)O(2) concentrations of each fraction. CONCLUSION: The new technique of fractionated H(2)O(2) measurement may differentiate H(2)O(2) concentrations in different parts of the lung in asthmatic and control children. H(2)O(2) concentrations of the alveolar fraction may be related to the asthma control test in children.