Immune Netw.  2003 Sep;3(3):201-210. 10.4110/in.2003.3.3.201.

Feedback Control of Cyclooxygenase-2 Expression by Prostaglandin E2 in Rheumatoid Synoviocytes

• Min SY
• Jung YO
• Do JH
• Kim SY
• Kim JP
• Cho CS
• Kim WU

• KMID: 1615311
• DOI: http://doi.org/10.4110/in.2003.3.3.201

Abstract

Objective
The role of prostaglandin E2 (PGE2) in the etiopathogenesis of immune and inflammatory diseases has become the subject of recent debate. To determine the role of PGE2 in rheumatoid arthritis (RA), we tested the effect of exogenous PGE2 on the production of cyclooxygenase-2 (COX-2) by rheumatoid synoviocytes. METHODS: Fibroblast-like synoviocytes (FLS) were prepared from the synovial tissues of RA patients, and cultured in the presence of PGE2. The COX-2 mRNA and protein expression levels were determined by RT-PCR and Western blot analysis, respectively. The PGE2 receptor subtypes in the FLS were analyzed by RT-PCR. Electrophoretic mobility shift assay (EMSA) was used to measure the NF-kappaB binding activity for COX-2 transcription. The in vivoeffect of PGE2 on the development of arthritis was also tested in collagen induced arthritis (CIA) animals. RESULTS: PGE2 (10(-11) to 10(-5) M) dose-dependently inhibited the expression of COX-2 mRNA and the COX-2 protein stimulated with IL-1beta, but not COX-1 mRNA. NS-398, a selective COX-2 inhibitor, displayed an additive effect on PGE2-induced COX-2 downregulation. The FLS predominantly expressed the PGE2 receptor (EP) 2 and EP4, which mediated the COX-2 suppression by PGE2. Treatment with anti-IL-10 monoclonal antibodies partially reversed the PGE2-induced suppression of COX-2 mRNA, suggesting that IL-10 may be involved in modulating COX-2 by PGE2. Experiments using an inducer and an inhibitor of cyclic AMP (cAMP) suggest that cAMP is the major intracellular signal that mediates the regulatory effect of PGE2 on COX-2 expression. EMSA revealed that PGE2 inhibited the binding of NF-kappaB in the COX-2 promoter via a cAMP dependent pathway. In addition, a subcutaneous injection of PGE2 twice daily for 2 weeks significantly reduced the incidence and severity of CIA as well as the production of IgG antibodies to type II collagen. CONCLUSION: Our data suggest that overproduced PGE2 in the RA joints may function as an autocrine regulator of its own synthesis by inhibiting COX-2 production and may, in part, play an anti-inflammatory role in the arthritic joints.

Keyword

Prostaglandin E2; synoviocytes; COX-2; cAMP; NF-kB

MeSH Terms

Animals
Antibodies
Antibodies, Monoclonal
Arthritis
Arthritis, Rheumatoid
Blotting, Western
Collagen
Collagen Type II
Cyclic AMP
Cyclooxygenase 2*
Dinoprostone*
Down-Regulation
Electrophoretic Mobility Shift Assay
Humans
Immunoglobulin G
Incidence
Injections, Subcutaneous
Interleukin-10
Joints
NF-kappa B
RNA, Messenger
Antibodies
Antibodies, Monoclonal
Collagen
Collagen Type II
Cyclic AMP
Cyclooxygenase 2
Dinoprostone
Immunoglobulin G
Interleukin-10
NF-kappa B
RNA, Messenger