Expression of microsomal prostaglandin E synthase 1 in rheumatoid arthritis synovium.
OBJECTIVE
Microsomal prostaglandin E synthase 1 (mPGES-1) catalyzes the formation of PGE(2) from cyclooxygenase-derived PGH(2). Microsomal PGES-1 is induced by proinflammatory cytokines and is strongly linked to conditions that result in high PGE(2) biosynthesis. PGE(2) contributes to the pathogenesis of rheumatoid arthritis (RA), acting as a mediator of inflammation and promoting bone destruction. Induction of mPGES-1 in rheumatoid synoviocytes by proinflammatory cytokines has been demonstrated in vitro, indicating an important role in RA pathogenesis. Recent studies using mPGES-1-deficient mice demonstrated the importance of this gene in chronic inflammation. The aim of this study was to investigate the expression and localization of mPGES-1 in synovial biopsy specimens obtained from patients with RA.


METHODS
Synovial tissue samples from 24 patients with RA were obtained, and immunohistologic analysis was performed using polyclonal antibodies against mPGES-1. Double immunofluorescence staining was performed with antibodies to CD3, CD19, CD20, CD68, CD163, and prolyl 4-hydroxylase.


RESULTS
Intracellular mPGES-1 staining was observed in synovial membranes from all of the RA patients studied. Specifically, strong expression of mPGES-1 was detected in synovial lining cells. In sublining mononuclear and fibroblast-like cells, the extent of mPGES-1 staining was less than that in the synovial lining cells. In some patients, positive staining was observed in endothelial cells. With the double immunofluorescence technique, mPGES-1 production was detected in synovial macrophages and fibroblasts, while mPGES-1 expression was not observed in lymphocytes.


CONCLUSIONS
The demonstration of mPGES-1 expression in synovial tissues from patients with RA suggests a role for mPGES-1 in the RA disease process. Microsomal PGES-1 might be a potential new target for treatment strategies to control PGE(2) synthesis in patients with RA, without the systemic side effects associated with cyclooxygenase inhibitors.
Westman
M
M
Karolinska Hospital, Stockholm, Sweden.
Korotkova
M
M
af Klint
E
E
Stark
A
A
Audoly
L P
LP
Klareskog
L
L
Ulfgren
A-K
AK
Jakobsson
P-J
PJ
D000918:Antibody Specificity; D001172:Arthritis, Rheumatoid / Q000378:metabolism* / Q000473:pathology; D015232:Dinoprostone / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D019746:Intramolecular Oxidoreductases / Q000276:immunology / Q000378:metabolism*; D008861:Microsomes / Q000201:enzymology; D000071876:Prostaglandin-E Synthases; D013583:Synovial Membrane / Q000201:enzymology* / Q000473:pathology
D019746:Intramolecular Oxidoreductases; C000605862:PTGES protein, human; D000071876:Prostaglandin-E Synthases; C000605865:Ptges protein, mouse; D015232:Dinoprostone