[Changing understanding and definition of bronchial asthma]

Asthma is characterized clinically with repeated episodes of wheezes and dyspnea, associated with at least partially reversible airway narrowing, physiologically increased airway responsiveness, pathologically inflammation of the airway with the infiltration of eosinophils, T cells and mast cells, and immunologically in around 2 thirds of patients, increased production of IgE antibodies to environmental allergens. Originally asthma was thought as a symptom complex with repeated episodes of wheezes and dyspnea, and bronchoconstriction. Then asthma was defined as a disease of airway hyperresponsiveness. Recently the understanding of asthma has changed from a disease of airway hyperresponsiveness to a disorder with chronic inflammatory disorder of the airway. The concept of asthma as a disease of airway hyperresponsiveness was thought to dictate that enough amount of bronchodilators would be given to prevent airway narrowing, however, this treatment sometimes gave a cause to increase of death from asthma by overuse of inhaled beta 2-agonists. After the recent introduction of understudying of asthma as inflammatory disorder of the airway, main approach of asthma treatment has become the control of airway inflammation by antiinflammatory agents with long-acting broncholilators and minimal use of rescue use of inhaled beta 2-agonists. Such changes have been propagated by asthma management guidelines in Japan and also worldwidely.