Premium
Mechanisms of the priming effect of lipopolysaccharides on the biosynthesis of leukotriene B 4 in chemotactic peptide‐stimulated human neutrophils
Author(s) -
Surette Marc E.,
Dallaire Nancy,
Jean Nathalie,
Picard Serge,
Borgeat Pierre
Publication year - 1998
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.12.14.1521
Subject(s) - stimulation , leukotriene b4 , priming (agriculture) , chemistry , arachidonic acid , phospholipase a2 , biochemistry , chemotaxis , arachidonate 5 lipoxygenase , receptor , microbiology and biotechnology , enzyme , biology , endocrinology , immunology , inflammation , botany , germination
The goal of this study was to explain the priming effect of lipopolysaccharides (LPS) in human polymorphonuclear leukocytes on leukotriene B 4 (LTB 4 ) biosynthesis after stimulation with the receptor‐mediated agonist formyl‐methionyl‐leucylphenylalanine (fMLP). This priming effect for LTB 4 biosynthesis was maximal after a 30 min preincubation with LPS but was lost when incubations were extended to 90 min or longer. Priming with LPS resulted in an enhanced maximal activation of 5‐lipoxygenase (5‐ to 15‐fold above unprimed cells) as well as a prolonged activation of the enzyme after stimulation with fMLP compared to that measured in unprimed cells. The activation of 5‐lipoxygenase was associated with its translocation to the nuclear fraction of the cell after stimulation of LPS‐primed cells but not of unprimed cells. Priming of cells with LPS also resulted in an enhanced capacity (fivefold increase) for arachidonic acid (AA) release after stimulation with fMLP compared to unprimed cells as measured by mass spectrometry. This release of AA was very efficiently blocked in a dose‐dependent manner by the 85 kDa cytosolic phospholipase A 2 (PLA 2 ) inhibitor MAFP (IC 50 = 10nM) but not by the 14 kDa secretory PLA 2 inhibitor SB 203347 (up to 5 µM), indicating that the 85 kDa cPLA 2 is the PLA 2 responsible for AA release in response to receptor‐mediated agonists. In accord with inhibitor studies, the LPS‐mediated phosphorylation of cPLA 2 followed the same kinetics as the priming for AA release, and a measurable fMLP‐induced translocation of cPLA 2 was observed only in primed cells. As with AA release and LTB 4 biosynthesis, both the phosphorylation and capacity to translocate cPLA 2 were reversed when the preincubation period with LPS was extended to 120 min. These results explain some of the cellular events responsible for the potentiation and subsequent decline of functional responses of human polymorphonuclear leukocytes recruited to inflammatory foci.—Surette, M. E., Dallaire, N., Jean, N., Picard, S., Borgeat, P. Mechanisms of the priming effect of lipopolysaccharides on the biosynthesis of leukotriene B 4 in chemotactic peptide‐stimulated human neutrophils. FASEB J. 12, 1521–1531 (1998)