Biosynthesis of eicosanoids and transcellular metabolism of leukotrienes in murine bone marrow cells

Abstract

Leukotriene B4 (LTB4) biosynthesis by polymorphonuclear leukocytes (PMNs) is an important factor of inflammatory responses. PMNs also release LTA4, an unstable intermediate that can be taken up by neighboring cells and metabolized into LTC4. Most studies of LT synthesis have been carried out using human PMNs, but very little information is available about mouse PMNs. Mouse bone marrow PMNs were found to synthesize eicosanoids upon stimulation with A23187, fMLP, or zymosan. The major eicosanoids produced are LTB4 and 5-hydroxyeicosatetraenoic acid, with some nonenzymatic products of LTA4 hydrolysis. No cysteinyl leukotrienes were produced, in contrast to what was observed with human blood neutrophil preparations. Human megakaryoblast-like MEG-01 cells synthesized thromboxane B2 and prostaglandin E2 in response to A23187 but produced no 5-lipoxygenase (5-LO)-derived eicosanoids. When mouse bone marrow cells (mBMCs) and MEG-01 cells were stimulated during coincubation, LTC4 and LTD4 were produced. Mouse peritoneal macrophages from 5-LO-deficient mice were able to synthesize LTC4 when incubated with mBMCs from wild-type mice, demonstrating transcellular exchange of LTA4 from mBMCs into murine peritoneal macrophages. These data demonstrate that murine bone marrow PMNs are a valid model for the study of LT biosynthesis, which now offers the possibility to investigate specific biochemical pathways through the use of transgenic mice.

Keywords

• murine neutrophils
• leukotriene B4
• leukotriene C4
• MEG-01 cells
• mass spectrometry