EPITHELIAL-CELLS

The airway epithelium is the first line of defence against air-borne dusts, vapour, gases and fumes and plays a vital role in the maintenance of physico-chemical homoeostasis. Perturbation of the epithelial cells which predominate within this barrier, may bring about adverse changes in and around the surrounding tissues playing a part in the pathogenesis of asthma. Although the specific mechanism(s) which partake in pathogenesis are not clear, several have been proposed. These include: (1) increased synthesis and release of inflammatory mediators and decreased synthesis of protective mediators; (2) synthesis of inflammatory cytokines; (3) modulation of cell adhesion molecules, important in determination of epithelial architecture; and (4) immunoregulation of the inflammatory cell types. It is likely that these operate together and interact to produce, initially functional changes in the epithelium, which lead eventually to the structural changes that are characteristic of the airway epithelium of asthmatics.