Injurious effects of mineral dust – elicited bronchoalveolar leukocytes on epithelial cells in vitro: the role of extracellular matrix components.

Deposition of mineral dust associated with the development of pneumoconiosis causes a range of changes in the lung parenchyma including alveolar inflammation and, in the longer term, septal fibrosis and epithelial abnormalities (Begin et al. 1986; Gibbs et al. 1984). We have been studying the role of inflammatory leukocytes in the development of pathology in dust-exposed lung and have previously reported on the ability of inflammatory bronchoalveolar leukocytes from rat lung, exposed by intratracheal installation to quartz, to cause proteolytic injury to cells of an alveolar epithelial cell line in vitro (Donaldson et al. 1988c). In the present paper we extend these studies by examining inflammatory bronchoalveolar leukocytes lavaged from chrysotile asbestos-exposed lung, in terms of ability to cause epithelial injury in vitro. We further report on the ability of bronchoalveolar leukocytes from lung exposed by the more appropriate inhalation route to coalmine dust, with the regard to causing epithelial injury and proteolytic degradation of fibronectin. In order to study the role of the extracellular matrix in epithelial injury in vitro, we have examined the ability of exogenous protease and mineral dust-elicited inflammatory bronchoalveolar leukocytes, to injure epithelial cells cultured on surfaces coated with purified extracellular matrix components.