Il-6 levels in exhaled breath condensate (EBC) of children with moderate well-controlled asthma stepping down inhaled corticosteroids

Introduction: IL-6 is a cytokine related to inflammation and remodeling. Increased serum levels have been reported in asthma and related to severity. Respiratory epithelium produces IL-6; some studies have shown elevated levels in patients9 sputum and in EBC. In the EBC not all the studies have found it present and findings are controversial. Objective: to estimate the levels of IL-6 in the EBC of children with moderate well-controlled asthma and to analyze their association with spirometry and treatment. Methods: from a library of EBC samples from a cohort of children with moderate asthma followed quarterly, samples were selected for visits in which a child was asymptomatic, with normal spirometry, and with well controlled asthma (ACT) in the previous 6 months. In all of them, inhaled corticosteroid had been decreased or suspended 3 months before. At all visits ACT, EBC sample, and spirometry with bronchodilator test were taken. In the EBC samples pH was measured and the nitrites/nitrates (Griess) and IL-6 (ELISA) levels were evaluated. Association between IL-6 and the rest of the variables was searched. Results: samples from 45 children (10+3 years) met the inclusion criteria. At 38 the IL-6 was below the limit of detection (3.1 pcg/ml) and in 7 it could be dosed (range 3.1-8.8). The detection of IL-6 levels was associated with a greater response to bronchodilator (p0.08) and to the absence of treatment with inhaled corticosteroids (p0.0001), both being independent variables (chi-square 1.09). Conclusion: high levels of IL-6 may be an early sign of inflammation in some children with controlled asthma who are stepping down inhaled corticosteroids.