For many years epithelial cells were considered to have the simple role of a barrier participating to mucous secretion and removal of noxious agents by their cilia. Some patients present a simple stratified non-ciliated epithelium with frequent mitoses that may represent a regeneration of the bronchial mucosa.
Some patients have an increase in goblet cells.
However both partial epithelial shedding and increase of goblet cells can be observed in normal non-smoking subjects due to artifacts of the biopsic procedure. The consequences of epithelial shedding are likely to be or major importance in the pathogenesis of asthma. Nadel was the first to focus on the epithelial cell damage and suggested that asthma resulted from an epithelial injury that increases the freshold of re- flexes narrowing the airways. The deleterious role of bronchial epithelium in asthma is unclear. It is likely that eicosanoids are involved.