Eicosapentaenoic acid inhibits prostaglandin D2 generation by inhibiting cyclo-oxygenase-2 in cultured human mast cells.
BACKGROUND
Eicosapentaenoic acid (EPA) is catalysed by cyclo-oxygenase (COX), as is arachidonic acid, and is a competitive inhibitor of arachidonate metabolism.


OBJECTIVE
We examined the effect of EPA on prostaglandin (PG) D2 generation in the cultured human mast cells with IgE-anti-IgE challenge incubation.


METHODS
Cultured human mast cells were incubated with EPA (1 micromol/L) for 20 h, then challenged with anti-IgE incubation after treatment with IgE. At the same time, COX inhibitors were tested to identify COX-1 and COX-2 activity. PGD2 synthetic activity was also assayed in a cell-free homogenate of cultured mast cells with COX inhibitors and EPA. Histamine in the culture medium and in cells was assayed with the HPLC-fluorescent method. PGD2 and PGD3 were assayed with gas chromatography-mass spectrometry and the stable isotope dilution method.


RESULTS
Although EPA incubation did not affect histamine release by cultured human mast cells in response to IgE-anti-IgE challenge incubation, it did decrease PGD2 generation by inhibiting the COX-2 pathway. In contrast, in the cell-free homogenate of cultured human mast cells, EPA inhibited both COX-1 and COX-2 activities.


CONCLUSIONS
Pre-incubation with EPA primarily affects the COX-2 pathway in cultured human mast cells and reduces PGD2 generation in response to IgE-anti-IgE challenge incubation. These findings suggest that COX-1 and COX-2 have different substrate flow systems in mast cells. They also suggest that endogenous EPA diet supplementation would reduce PGD2 production and could serve as an anti-inflammatory substrate in human mast cells.
Obata
T
T
Department of Molecular Cell Biology, Institute of DNA Medicine, Jikei University School of Medicine, Tokyo, Japan.
Nagakura
T
T
Masaki
T
T
Maekawa
K
K
Yamashita
K
K
D000906:Antibodies / Q000276:immunology; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D015118:Eicosapentaenoic Acid / Q000494:pharmacology*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006636:Histamine Release; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D007527:Isoenzymes / Q000378:metabolism*; D008407:Mast Cells / Q000187:drug effects / Q000201:enzymology*; D008565:Membrane Proteins; D015230:Prostaglandin D2 / Q000378:metabolism*; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*
D000906:Antibodies; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D007073:Immunoglobulin E; D015118:Eicosapentaenoic Acid; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D015230:Prostaglandin D2