Epithelial Cells: Barrier Functions and Shedding-Restitution Mechanisms

摘要

Microvascular-epithelial exudation of bulk plasma is increased in patients with asthma, as evidenced by an increased concentration of plasma proteins in sputum and bronchoalveolar la-vage fluid (1). Mucosal absorption is unchanged or even decreased in exudative eosinophilic airway disease (2, 3). Shedding of epithelial cells is increased in patients with asthma, although the extent to which the epithelium is shed is variable, and the shedding is patchy. There is debate about whether shedding of airway epithelium is an artifact of the fiberoptic biopsy procedure, but it is possible that the airway epithelium is more fragile in patients with asthma. The evidence for shedding observed in bronchial biopsy specimens is supported by increased numbers of epithelial cells in the bronchoalveolar lavage fluid and sputum of patients with asthma (4, 5).