Comment comprendre la maladie asthmatique.

Abstract

L' asthme est l' une des affections chroniques les plus frequentes et represente un probleme de sante publique mondial. L' apport de la recherche epidemiologique, fondamentale et clinique a abouti a une reduction de la severite de l' asthme au cours de ces dix dernieres annees. L' asthme est un syndrome multifactoriel a determinisme genetique dans lequel interviennent des facteurs de l' environnement dont les allergenes. L' allergie est la cause la plus frequente de l' asthme et les premiers travaux de genetique se sont focalises sur les genes de la reponse immune a l' allergene. Les cytokines de type Th2, representees par les interleukines IL-4, IL-5 et IL-13, sont responsables de l' allergie dans l' asthme. L' inflammation bronchique est complexe mettant en jeu l' ensemble des cellules de l' arbre bronchique et des cellules inflammatoires. Il existe des similitudes entre asthme allergique et non allergique comme le demontrent les etudes de biopsies bronchiques dans lesquelles les eosinophiles et le recepteur des IgE sont presents. La severite de l' asthme est liee a court terme au bronchospasme, a moyen terme a l' inflammation bronchique et, a long terme, au remodelage anormal des voies aeriennes. Les tres nombreux travaux de recherche qui ont ete realises depuis 20ans ont permis d' apprecier l' importance de l' inflammation et du remodelage bronchique et d' orienter la strategie therapeutique vers le traitement anti-inflammatoire.

Asthma is a major public health problem which concerns all countries in the world. Extensive basic, epidemiologic and clinical research has been carried out in asthma during the past 15 years to better understand the mechanisms of the disease as well as its prevalence and risk factors in order to reduce the morbidity and mortality of the disease. It has been shown that asthma prevalence is increasing in all countries in the world. Asthma is often linked with allergies and rhinitis. The genetic component of asthma was highlighted. Asthma is a multifactorial and complex disease in which allergic factors and nonallergic triggers are interacting and result in bronchial obstruction and inflammation. Allergic diseases are mediated by the triggering of IgE-bound mast cells by allergens leading to the release of vaso-active mediators and an ongoing inflammatory reaction causing non-specific hyperreactivity that may persist for several days. The repetition of allergen challenges leads to a complex inflammatory state eventually followed in the long term by airways remodelling. Treatment of asthma has benefited from guidelines. In 1995, the Global INitiative for Asthma was published by WHO and NIH and proposed a stepwise approach for asthma treatment.