Experimental Model of Bronchiolitis Obliterans : Pulmonary Response of Mice to High-Concentration Ozone Exposure
In order to elucidate the pathogenesis of bronchiolitis obliterans, an experimental model was produced in mice using highconcentration ozone. A single exposure to 3.5 p.p.m. of ozone for 4 hours diffusely developed occlusion of the terminal bronchioles. These lesions consisted mainly of hyperplasia of bronchiolar and alveolar epithelial cells. Four exposures, at intervals of 3 days, resulted in more intense regeneration of the terminal airways with fibrous polypoid lesions protruding from the bronchiolar wall into the lumen. Although these lesions morphologically resembled bronchiolitis obliterans in human cases, they did not persist for a long period after the exposure. The explanation for this transient occurrence and the mechanism of the damage remains to be clarified.