Uptake of 12-HETE by human bronchial epithelial cells (HBEC): effects on HBEC cytokine production.

Abstract 12-HETE, the major lipoxygenase end-product of platelets and macrophages, may be released in contact of bronchial epithelium in inflammatory diseases of the lung. We have studied the outcome of 12-HETE in presence of human bronchial epithelial cells (HBEC). When HBEC were incubated with [ 3 H]12-HETE for 30 minutes, 27.5% of total radioactivity was found in HBEC and 72.5% in supernatants. Unesterified 12-HETE accounted for 22.4% of total radioactivity, 4.5% being recovered in phospholipids, preferentially in phosphatidylcholine and phosphatidylethanolamine. No incorporation in neutral lipids was detected. 72.9% of the incubated radioactivity was recovered in un identified metabolites. As 12-HETE has been shown to modulate the expression and production of various proteins, the consequence of the 12-HETE uptake on the release of GM-CSF and IL8 by HBEC was assessed. HBEC from control subjects were cultured for 24 hours with 12-HETE (10 −9 to 10 −7 M) in the presence or absence of TNFα. Detectable amounts of both cytokines were released in the supernatant in basal conditions at 24hr, and TNFα increased significantly the release of GM-CSF. 12-HETE at 10 −7 M weakly but significantly decreased the TNF-induced release of GM-CSF from HBEC. Thus the uptake of 12-HETE could affect the epithelial cell function in some situations.