Clinico-biological Correlation of Severe Asthma in Children

Asthma is the most common chronic respiratory disorder in children. Despite significant advances in understanding of asthma, available therapies fail to alter the natural history and progression of the disease. Airway epithelial cells are continuously exposed to and injured by environmental irritants, such as viruses and pollutants, and as such are ideally situated to orchestrate airway function in response to these stimuli. Severe or difficult-to-treat asthma in children is a complicated disorder characterized by ongoing symptoms and persistent airway inflammation and oxidant stress despite corticosteroid treatment. Although severe asthma is likely a heterogeneous disorder, affected children similar clinical features, including gas trapping, bronchial hyperresponsiveness, and aeroallergen sensitization. However, the molecular and cellular pattern of inflammation in children with severe asthma are not uniform : some investigators have found increased eosinophils and TH2 derived cytokines, others have noted noneosinophilic patterns with neutrophil activation. Given the heterogeneity of the inflammatory response in children with severe asthma, additional methods to distinguish severe asthma are needed.