Coexpression of microsomal prostaglandin E synthase with cyclooxygenase-2 in human rheumatoid synovial cells.
OBJECTIVE
Recently, microsomal prostaglandin (PG) E synthase (mPGES) was cloned as a terminal enzyme catalyzing PGH2 to PGE2. We investigated mPGES as well as cyclooxygenase (COX)-2, catalyzing arachidonic acid to PGH2, in synovial cells from patients with rheumatoid arthritis (RA). The effect of dexamethasone on mPGES expression was also studied.


METHODS
Synovial cells were treated with interleukin 1beta (IL-1beta) and dexamethasone under various conditions, and expression of mPGES mRNA and protein was analyzed by Northern blot and Western blot, respectively. Conversions of arachidonic acid or PGH2 to PGE2 were measured by ELISA. Subcellular localization of mPGES and COX-2 was determined by immunofluorescent microscopic analysis.


RESULTS
mPGES mRNA and protein expression were significantly upregulated by IL-1beta in synovial cells. COX-2 mRNA and protein were also upregulated by IL-1beta, but with a different time course from that of mPGES. Conversion of PGH2 to PGE2 increased by IL-1beta and was correlated with mPGES expression. Increased conversion of arachidonic acid to PGE2 was maintained when mPGES and COX-2 were coexpressed. Subcellular localization of mPGES and COX-2 overlapped in the perinuclear region in IL-1beta stimulated synovial cells. Dexamethasone inhibited mRNA and protein expression for mPGES and increased conversion of arachidonic acid to PGE2, but inhibition of mPGES was weaker compared with that of COX-2 in IL-1beta stimulated cells.


CONCLUSIONS
The results suggest that abundant PGE2 production at inflammation sites such as rheumatoid synovia is caused by the coordinated upregulation of mPGES and COX-2. Thus mPGES might be a potential new target for therapeutic strategies to control PGE2 synthesis specifically in patients with RA and other inflammatory diseases.
Kojima
Fumiaki
F
Department of Pharmacology, School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan.
Naraba
Hiroaki
H
Sasaki
Yasuharu
Y
Okamoto
Renzo
R
Koshino
Tomihisa
T
Kawai
Shinichi
S
D001172:Arthritis, Rheumatoid / Q000201:enzymology* / Q000473:pathology; D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D003907:Dexamethasone / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000032:analysis*; D007375:Interleukin-1 / Q000494:pharmacology; D019746:Intramolecular Oxidoreductases / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*; D007527:Isoenzymes / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins; D008861:Microsomes; D000071876:Prostaglandin-E Synthases; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis*; D012680:Sensitivity and Specificity; D013583:Synovial Membrane / Q000166:cytology / Q000201:enzymology*; D013585:Synovitis / Q000201:enzymology / Q000473:pathology
D018836:Inflammation Mediators; D007375:Interleukin-1; D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D003907:Dexamethasone; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D019746:Intramolecular Oxidoreductases; D000071876:Prostaglandin-E Synthases