Reactive oxygen metabolites appear to be involved in the pathogenesis of many pulmonary and cardiovascular lesions. Acute lung injury, edema, vasoconstriction, airways hyperreactivity and fibrosis are associated with oxidant injury. Despite their deleterious effects, mechanisms of intracellular responses to oxidants are not well-understood. Activation of specific pathways of arachidonic acid metabolism may be basic mechanisms of response to oxidant injury in different cells and tissues. Preliminary studies by the applicant indicate oxidants are capable of enhancing mucin secretion by explants of airway tissue maintained in organ culture, suggesting another pathogenetic mechanism (excess mucus secretion) associating these substances with the development of pulmonary disorders. A novel procedure for culturing epithelial cells from rodent airways has been developed in this laboratory. Proteolytically-dispersed cells from guinea pig trachea proliferate and differentiate into a pseudostratified columnar epithelial configuration identical morphologically and functionally to mucosal epithelium observed in the intact animal. The system offers the advantages of a pure population of epithelial cells, but also maintained in the same orientation and relationships to allow for cell-cell interactions that undoubtedly influence function of epithelium in vivo and in situ. The cells secrete mucin identical biochemically to that released by airway explants, and respond to secretagogues in a similar manner. In the proposed research, respiratory epithelium maintained in this unique cell culture system will be exposed in vitro to chemically-generated oxidants. Effects on mucin secretion will be correlated with phosphoinositide metabolism and production of arachidonate metabolites within the epithelial cells. The studies will elucidate mechanisms of stimulated mucin secretion after exposure of respiratory epithelium to oxidants. They also will serve as a model for study of possible common intracellular metabolic pathways involved in response of a variety of cell and tissue types to oxidant injury.
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