Expression and regulation of microsomal prostaglandin E synthase-1 in human osteoarthritic cartilage and chondrocytes.
OBJECTIVE
Elevated production of prostaglandin E2 (PGE2) plays an important role in the pathogenesis of arthritis. Recently, an inducible microsomal prostaglandin E synthase-1 (mPGES-1) was identified. This enzyme is functionally coupled with cyclooxygenase-2 (COX-2) and converts the COX product PGH2 to PGE2. We analyzed expression of mPGES-1 in human normal and osteoarthritic (OA) cartilage and determined the effect of different inflammatory agonists on the expression of mPGES-1 in OA chondrocytes.


METHODS
Expression of mPGES-1 mRNA and protein in cartilage was determined by quantitative real-time reverse transcriptase-polymerase chain reaction and immunohistochemistry, respectively. OA chondrocytes were treated with different inflammatory agents, and mPGES-1 protein expression was evaluated by Western blot. Activation of the mPGES-1 promoter was assessed in transient transfection experiments.


RESULTS
Levels of mPGES-1 mRNA and protein were markedly elevated in OA versus normal cartilage. Treatment of chondrocytes with interleukin 1beta (IL-1beta) induced expression of mPGES-1 protein in a dose- and time-dependent manner. This appears to occur at the transcriptional level, as IL-1beta induced expression of mPGES-1 mRNA and the activity of this gene promoter. Tumor necrosis factor-alpha (TNF-alpha) and IL-17 also upregulated expression of mPGES-1 protein and displayed a synergistic effect with IL-1beta. Peroxisome proliferator-activated receptor-gamma ligands, 15-deoxy-delta(12,14)-prostaglandin J2 and troglitazone, inhibited IL-1beta-induced mPGES-1 protein expression, an effect that was reversed by exogenous PGE2.


CONCLUSIONS
Our study shows that mPGES-1 expression is upregulated in OA versus normal cartilage and that proinflammatory cytokines increased mPGES-1 expression in chondrocytes. These data suggest that mPGES-1 may prove to be an interesting therapeutic target for controlling PGE2 synthesis.
Li
Xinfang
X
Osteoarthritis Research Unit, Centre hospitalier de l'Université de Montréal, Hôpital Notre-Dame, Montréal, Québec, Canada.
Afif
Hassan
H
Cheng
Saranette
S
Martel-Pelletier
Johanne
J
Pelletier
Jean-Pierre
JP
Ranger
Pierre
P
Fahmi
Hassan
H
D000368:Aged; D002358:Cartilage, Articular / Q000473:pathology / Q000502:physiology*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D015232:Dinoprostone / Q000378:metabolism / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D020381:Interleukin-17 / Q000494:pharmacology; D019746:Intramolecular Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D008861:Microsomes / Q000201:enzymology*; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D047495:PPAR gamma / Q000378:metabolism; D015230:Prostaglandin D2 / Q000031:analogs & derivatives* / Q000494:pharmacology; D000071876:Prostaglandin-E Synthases; D012333:RNA, Messenger / Q000032:analysis; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
C477819:15-deoxyprostaglandin J2; D007375:Interleukin-1; D020381:Interleukin-17; D047495:PPAR gamma; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D019746:Intramolecular Oxidoreductases; C000605862:PTGES protein, human; D000071876:Prostaglandin-E Synthases; D015232:Dinoprostone; D015230:Prostaglandin D2