Bronchial epithelium: morphology, function, and pathophysiology in asthma

Human bronchial epithelium has a number of mechanical functions, including mucociliary clearance and protection against noxious agents. Bronchial epit helial cells are also able to release a variety of mediators, including cyt okines, chemokines, growth factors, and arachidonic acid metabolites, which are able to regulate the recruitment, activation, and differentiation of i nflammatory cells. They also modulate the function of the underlying smooth muscle cells by the release or metabolism of bronchoactive mediators. Fina lly, bronchial epithelial cells may control inflammatory reactions by the r elease of anti-inflammatory mediators or by the inactivation of pro-inflamm atory mediators. Morphological or functional abnormalities of the bronchial epithelium mag contribute to the initiation, perpetuation and prolongation of inflammatory processes and thereby to the pathogenesis of asthma, In th is review, the morphology of the bronchial epithelium, its function with re gard to host defense, and its immunological potential will be reviewed, Alt erations associated with asthma will be emphasized.