Human airway monohydroxyeicosatetraenoic acid generation and mucus release

The effects of 5-, 8-, 9-, 11-, 12-, and 15-monohydroxyeicosatetraenoic acid (HETE) (0.1-10 nM) on mucous glycoprotein release from cultured human airways were determined. Each of the HETE was an active secretagogue of mucus at concentrations >1-10 nM with 12- and 15-HETE, the most active. Both 5- and 9-hydroperoxyeicosatetraenoic acid (HPETE) were also active as secretagogues at 100 nM, although of somewhat low potency. As cultured airways were capable of responding to HETE with mucous glycoprotein release, it was of interest to identify and quantitate airway HETE formation. Accordingly, airways were incubated with tracer quantities of [¹⁴C]arachidonate for 16-48 h, and the spontaneous formation of 5-, 12- and 11- and/or 15-HETE was measured by high-pressure liquid chromatography. Indeed, sizeable quantities of 11- and/or 15- > 5- > 12-HETE were generated. This HETE generation was increased by the addition of 25 μg/ml of arachidonate and was reduced somewhat after 18-21 d in continuous tissue culture. Reversed anaphylaxis of human airways using anti-human IgE markedly increased the HETE formation, resulting in the production of micromolar concentrations of 5- and 11- and/or 15-HETE. Thus, human airways not only are capable of responding to the presence of HETE with mucous glycoprotein release, but also generate (both spontaneously and in response to anaphylaxis) at least three species of HETE, and do so in quantities capable of acting as mucus secretagogues.