Ozone-Induced Proliferative and Metaplastic Lesions in Nasal Transitional and Respiratory Epithelium: Comparative Pathology

Abstract

This article reviews the proliferative and metaplastic responses of two distinct nonolfactory nasal epithelia (i.e., transitional and respiratory) in laboratory animals after repeated exposures to a common urban air pollutant, ozone. Alterations in these epithelia after either acute or chronic exposures are described. Ozone exposures induce lesions predominantly in the anterior aspects of the nasal airways in laboratory rats and monkeys. The principal epithelial alteration induced by this potent oxidant pollutant is a marked mucous cell hyperplasia/metaplasia in the transitional epithelium. Attenuation and loss of cilia are common ozone-induced lesions in the respiratory epithelium. In this article, we also compare the nasal epithelial lesions induced by ozone exposures in laboratory animals to nasal histopathology reported in human subjects living in ozone-polluted regions of Mexico City.