[Physiopathology of asthma]

Bronchial asthma is a unique disease; knowledge of the pathophysiology increases rapidly and underlines that is more a syndrome than a disease. Indeed a new definition has been recently proposed: desquamative eosinophilic chronic bronchitis. The airway obstruction, which is responsible for the wheezing breathlessness, is the consequence of a spasm but also an inflammation. After activation of the resident cells in the airways (mast cells, epithelial cells and alveolar macrophages), mediators are released and - in cooperation with the nervous system-recruit inflammatory cells from blood and bone marrow (mainly eosinophils). A kind of vicious circle seems to amplify the initial (allergic or not) event. Desquamation of the epithelium and disposition of collagen on the basement membrane take a quite long time to be cleared after an asthma attack. Mechanisms of repair must be studied in order to improve treatment. Bronchial asthma is not really a disease; indeed a lot of precipitating agents are able to induce and increase bronchial hyperreactivity. Allergy is the most important factor; but environment, hormones and other infectious agents could be quite important in many patients.