5-15-dihydroxy-6-8-11-13-eicosatetraenoic-acid and Asthma

5-Lipoxygenase activation of human blood polymorphonuclear cells (PMN) from asthmatic patients (asthmatics) was studied to investigate whether differences may exist with healthy subjects (controls). The respective cell capacities to produce lipoxins (LXs), leukotrienes, and 5(S), 15(S)-dihydroxyeicosatetraenoic acid [5(S),15(S)-diHETE] were compared under in vitro stimulation by ionophore A23187, with or without exogenous 15(S)-hydroxyeicosatetraenoic acid [15(S)-diHETE]. Eicosanoids were analyzed by elution with an isocratic reverse-phase high performance liquid chromatography system, and their profiles, detected by simultaneous monitoring at 302, 280, and 246 nm, were evaluated on the basis of chromatographic behavior: UV spectral characteristics and coelution with synthetic standards. In the presence of exogenous 15(S)-HETE, human PMN were able to produce LXs and 5(S),15(S)-diHETE, PMN from asthmatics were able to produce 5(S), 5(S),15(S)-diHETE, and LXs from endogenous sources, whereas in the same experimental conditions, no detectable amounts of these compounds were released by PMN from controls. The levels of 5(S),15(S)-diHETE, and LXs biosynthesized from endogenous arachidonic acid were highly correlated. Two different LX patterns were observed involving two possible metabolic pathways: (a) via the intermediate 5,6-epoxytetraene alone for LXs generation from exogenous 15(S)-HETE; and (b) via 5,6- and/or 14,15-epoxytetraenes leading to the formation of an enzyme-bound delocalized carbocation for LXs generation from endogenous arachidonate, respectively. The enhanced 5-lipoxygenase activation of blood PMN from asthmatics and the metabolism of exogenous 15(S)-HETE may reflect a priming induced by various mediators released from environmental cells, and could be considered as a model of transcellular signalization between PMN and endothelial cells.

Topics: Arachidonate 5-Lipoxygenase; Arachidonic Acids; Asthma; Calcimycin; Chromatography, High Pressure Liquid; Female; Humans; Hydroxyeicosatetraenoic Acids; Male; Models, Biological; Neutrophil Activation; Substrate Specificity

5-Lipoxygenase (5-LO) activation of human blood polymorphonuclear cells (PMN) from healthy subjects (HS) and from asthmatic patients (AP) was investigated comparing their respective capacities to produce lipoxins, 5,15-dihydroxyeicosatetraenoic acid (5,15-diHETE) and leukotrienes, under in vitro stimulation by ionophore A23187. PMN from AP were able to generate higher leukotriene levels from endogenous sources than PMN from HS. Moreover they produced 5,15-diHETE (from 50 to 280ng/10(7) cells) and lipoxins (from 1 to 30ng/10(7) cells), in a linear manner, whereas in the same experimental conditions no detectable amounts of these compounds appeared in PMN from HS. The enhanced 5-LO activation of blood PMN may reflect transcellular signalisation priming indicating that lipoxins and 5,15-diHETE could be much more specific inflammatory state biomarkers than leukotriene B4.

Topics: Arachidonic Acid; Asthma; Biomarkers; Calcimycin; Chromatography, High Pressure Liquid; Humans; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Neutrophils; Reference Values