Abstract
Leukotriene B(4) (LTB(4)) biosynthesis by polymorphonuclear leukocytes (PMNs) is an important factor of inflammatory responses. PMNs also release LTA(4), an unstable intermediate that can be taken up by neighboring cells and metabolized into LTC(4). 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 LTB(4) and 5-hydroxyeicosatetraenoic acid, with some nonenzymatic products of LTA(4) 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 B(2) and prostaglandin E(2) 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, LTC(4) and LTD(4) were produced. Mouse peritoneal macrophages from 5-LO-deficient mice were able to synthesize LTC(4) when incubated with mBMCs from wild-type mice, demonstrating transcellular exchange of LTA(4) 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.
Highlights
Leukotriene B4 (LTB4) biosynthesis by polymorphonuclear leukocytes (PMNs) is an important factor of inflammatory responses
In a calcium-dependent manner, cytosolic phospholipase A2 (cPLA2a) translocates from the cytosol to intracellular membranes that include the Golgi apparatus, the endoplasmic reticulum, and the nuclear envelope; at this location, it is in close proximity to some of the enzymes that use arachidonic acid (AA) for eicosanoid biosynthesis
Incubation of mouse bone marrow cell (mBMC) with 2 mM A23187 for 10 min resulted in the formation of different COX- and 5-LO-derived eicosanoids, as determined by online liquid chromatographytandem mass spectrometry (LC-MS/MS) techniques (Fig. 1). mBMCs were isolated from femurs and tibias and subjected to density gradient centrifugation
Summary
Leukotriene B4 (LTB4) biosynthesis by polymorphonuclear leukocytes (PMNs) is an important factor of inflammatory responses. 0.44 6 0.16 n.d. n.d. n.d. n.d. 5-HETE, 5-hydroxyeicosatetraenoic acid; hPMN, human peripheral blood polymorphonuclear leukocyte; LT, leukotriene; mBMC, mouse bone marrow cell; n.d., not detected.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have