Characterization of prostaglandin E2 generation through the cyclooxygenase (COX)-2 pathway in human neutrophils

Mireille St-Onge, Nicolas Flamand, Jordane Biarc, Serge Picard, Line Bouchard, Andrée Anne Dussault, Cynthia Laflamme, Michael J. James, Gillian Caughey, Leslie G. Cleland, Pierre Borgeat, Marc Pouliot

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40 Citations (Scopus)

Abstract

In the present study, we characterized the generation of prostaglandin (PG)E2 in human neutrophils. We found that the Ca2+-dependent type IV cytosolic phospholipase A2 (cPLA2) was pivotally involved in the COX-2-mediated generation of PGE2 in response to a calcium ionophore, as determined by the use of selected PLA2 inhibitors. PGE2 biosynthesis elicited by bacterial-derived peptides or by phagocytic stimuli acting on cell surface receptors also showed to be dependent on cPLA2 activity. We then assessed metabolism of unesterified arachidonic acid (AA), and observed that PGE2 production becomes favored over that of LTB4 with higher AA concentrations. Withdrawal of calcium prevented the generation of PGE2 in response to a calcium ionophore but did not affect the up-regulation of COX-2 or its capacity to convert AA, thus limiting its implication at the level of cPLA2 activation. Of the main eicosanoids produced by neutrophils, only LTB4 was able to up-regulate COX-2 expression. Finally, the only PGE synthase isoform found in neutrophils is microsomal PGE synthase-1; it co-localized with COX-2 and its expression appeared mainly constitutive. These results highlight key differences in regulatory processes of the 5-LO and COX pathways, and enhance our knowledge at several levels in the PGE2 biosynthesis in neutrophils.

LanguageEnglish
Pages1235-1245
Number of pages11
JournalBiochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
Volume1771
Issue number9
DOIs
Publication statusPublished - 1 Sep 2007

Keywords

  • Cyclooxygenase
  • Eicosanoids
  • Fatty acid
  • Inflammation
  • Polymorphonuclear leukocyte
  • Prostaglandins

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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