This article has no abstract; the first 100 words appear below.

Despite the availability of treatments such as glucocorticoids, leukotriene antagonists, long-acting bronchodilators, and a monoclonal antibody directed against IgE, a substantial proportion of patients with asthma continue to have uncontrolled disease.1 Exacerbations requiring hospitalization and ongoing treatment with a regular maintenance dose of systemic glucocorticoids cause substantial morbidity and impair the quality of life of these patients.Recognition of the components of the airway disease that contribute to the severity (airway hyperresponsiveness and inflammation and airflow limitation) and the underlying mechanisms of those abnormalities is a logical starting point on the path toward the development of strategies to target and . . .