Tight junctions (TJ) play a major role in maintaining the integrity of epithelia. Damage of conducting airway surface epithelium is commonly observed in asthma, and recent data suggest that epithelial cells modulate airway smooth muscle tone by the production of relaxant factor(s). To evaluate the ultrastructure of tight junctions (TJ) in human bronchial epithelium of normal and diseased lung, biopsy samples were obtained by fiberoptic bronchoscopy in three normal healthy subjects, four asthmatic patients with bronchial hyperreactivity to methacholine and one heavy smoker with chronic bronchitis. Specimens were examined by electron microscopy, using both thin sections and freeze-fracture techniques. In normal subjects two types of TJ were identified, based on 27 type I, 23 type II junctional areas. Epithelium from the patient with chronic bronchitis showed extensive mucous metaplasia and only junctions of the second type. Extensive epithelial damage was detected in asthmatic subjects, so that a few TJ could be found. Varying degrees of TJ abnormalities were observed and the possible role of such ultrastructural derangements was discussed.
A freeze-fracture study of human bronchial epithelium in normal, bronchitic and asthmatic subjects
BUCCA, Caterina;ROLLA, Giovanni;
1987-01-01
Abstract
Tight junctions (TJ) play a major role in maintaining the integrity of epithelia. Damage of conducting airway surface epithelium is commonly observed in asthma, and recent data suggest that epithelial cells modulate airway smooth muscle tone by the production of relaxant factor(s). To evaluate the ultrastructure of tight junctions (TJ) in human bronchial epithelium of normal and diseased lung, biopsy samples were obtained by fiberoptic bronchoscopy in three normal healthy subjects, four asthmatic patients with bronchial hyperreactivity to methacholine and one heavy smoker with chronic bronchitis. Specimens were examined by electron microscopy, using both thin sections and freeze-fracture techniques. In normal subjects two types of TJ were identified, based on 27 type I, 23 type II junctional areas. Epithelium from the patient with chronic bronchitis showed extensive mucous metaplasia and only junctions of the second type. Extensive epithelial damage was detected in asthmatic subjects, so that a few TJ could be found. Varying degrees of TJ abnormalities were observed and the possible role of such ultrastructural derangements was discussed.
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