Prostaglandin ethanolamides or prostamides are naturally occurring neutral lipid derivatives of prostaglandins that have been shown to be synthesised in vivo following COX-facilitated oxygenation of arachidonyl ethanolamine (anandamide). Although the actions of prostaglandins have been extensively studied, little is known about the physiological or pathophysiological effects of prostamides. Since prostaglandin E2 has potent immunosuppressive/ immunomodulating actions, the aim of the present study was to determine whether the derivative, prostaglandin E2 ethanolamide (PGE2-EA), could modulate production of the pro- inflammatory cytokine tumour necrosis factor-α in human blood and human monocytic cells and indicate whether this action involved the same receptor systems/ signals as PGE2. Whole human blood, monocytes isolated from the blood or the human monocytic cell line THP-1were incubated with LPS and the level of TNFα produced was measured by ELISA assay. The actions of PGE2-EA were assessed on the LPS-induced TNF-α release. In addition, in order to ascertain the receptors involved, the levels of cyclic AMP in cells was measured in monocytes and THP-1 cells in response to PGE2-EA and directly compared to PGE2. The effect of PGE2-EA on the binding of radiolabelled PGE2 to cells was also measured. Cells were incubated with radiolabelled arachidonic acid and ethanolamine to estimate the production of PGE2-EA. PGE2-EA potently suppressed TNF-α production in blood, monocytes and the cell line THP-1 in a concentration-dependent manner. This occurred via cyclic AMP pathways as indicated by agents which interfere with these pathways and also direct ligand binding experiments. It was also shown that the cells were able to endogenously produce PGE2-EA. This study reports that PGE2-EA can down regulate the production of TNF-α by human mononuclear cells in response to an immune stimulus, i.e. LPS-activated TLR-4, and that this appears to occur via a cAMP-dependent mechanism that most likely involves binding to the EP2 receptor.
|Number of pages||10|
|Journal||Biochimica et Biophysica Acta Molecular and Cell Biology of Lipids|
|Publication status||Published - Jun 2013|
- monocytic cells
- tumour necrosis
- cell biology