Differentiation dependency of eicosanoid enzyme expression in human tracheobronchial cells.

The expression of 15-lipoxygenase (15-LO) and prostaglandin H synthase-2 (PGHS-2) was studied in retinoic acid (RA) sufficient and RA-deficient normal human tracheobronchial epithelial (NHTBE) cell cultures. In the absence of RA, in which the cultures became squamous metaplastic, neither 15-LO nor PGHS-2 were expressed. In RA-sufficient cultures, which differentiated into a mucociliary epithelium, both enzymes were expressed: PGHS-2 during early phases and 15-LO during late stages of differentiation. Depending on the stage of differentiation, the RA-sufficient cultures produced PGE, and in the presence of exogenous linoleic acid (LA) 13-HODE. Experiments are underway to examine the effects of inflammatory cytokines on eicosanoid metabolism and the role these metabolites play in airway diseases.