Heterogeneity of asthma according to systemic inflammatory pattern in children

ABSTRACT

PURPOSE: Asthma is a chronic airway inflammation. We evaluated whether systemic inflammatory patterns could reflect the nature of airway inflammation. We assessed characteristics of asthma according to systemic inflammatory patterns. METHODS: A total of 413 children with asthma were enrolled in the study. Four systemic inflammatory patterns were classified according to eosinophil and neutrophil counts in peripheral blood. Children with neutrophil count> or =5,000/microL were defined as the NEU(hi) group, those with neutrophil count or =650/microL were defined as the EOS(hi) group, those with eosinophil count<240/microL as the EOS(lo) group. The remaining patients were excluded from the study. The characteristics of asthma include pulmonary function test results, bronchodilator response, airway hyperresponsiveness, and atopy. RESULTS: The EOS(hi) group had a lower PC20 (provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 second [FEV1]), a lower FEV1, and a higher immunoglobulin E level rather than the EOS(lo) groups, although there were no significant differences between the NEU(hi) and NEU(lo) groups. The eosinophil percentages of the induced sputum samples were higher in the EOS(hi) group than the EOS(lo) group and correlated with blood eosinophil counts. CONCLUSION: Eosinophilic inflammation was related to characteristics of asthma and sputum eosinophils. However, neutrophilic inflammation reflected neither asthma features, sputum neutrophils, nor eosinophilic inflammation. Further studies on blood neutrophils involving asthma phenotypes in terms of more specific characteristics of asthma should be needed in children.