Interleukin-1alpha and tumor necrosis factor alpha synergistically stimulate prostaglandin E2-dependent production of interleukin-11 in rheumatoid synovial fibroblasts.
OBJECTIVE
Interleukin-11 (IL-11), an IL-6-type cytokine, is thought to be involved in bone resorption via osteoclast differentiation. Here, we characterized the combined effect of IL-1alpha and tumor necrosis factor alpha (TNFalpha), major cytokines in the rheumatoid synovium, on the production of IL-11 by cultured rheumatoid synovial fibroblasts (RSFs).


METHODS
The amounts of IL-11, IL-6, and prostaglandin E2 (PGE2) were measured by enzyme-linked immunosorbent assay. IL-11 messenger RNA (mRNA) levels were determined by Northern blotting. Protein expression of cytosolic phospholipase A2 (cPLA2), cyclooxygenase 2 (COX-2), and protein kinase C (PKC) isoforms were determined by Western blotting.


RESULTS
IL-1alpha and TNFalpha synergistically stimulated RSFs to produce IL-11 at both the mRNA and protein levels. This synergistic effect was completely inhibited by indomethacin. The inhibition was prevented by PGE2, indicating that the synergistic effect of IL-1alpha and TNFalpha was PGE2-mediated. The cooperative effects of these 2 cytokines were also observed in the production of PGE2 and the expression of 2 regulatory enzymes in PGE2 production, cPLA2 and COX-2. The synergistic induction of IL-11 by IL-1alpha and TNFalpha was completely inhibited by a potent inhibitor of all isoforms of PKC, GF109203X. In contrast, phorbol myristate acetate, which induced a down-regulation of PKC, degrading all PKC isoforms except atypical PKC, did not affect the induction of IL-11.


CONCLUSIONS
These findings suggest that IL-1alpha and TNFalpha synergistically stimulate the production of IL-11 via their effects on PGE2 production in the rheumatoid joint, and that atypical PKC may be another target for down-regulation of IL-11, the bone resorption-associated cytokine.
Mino
T
T
Toyama Medical and Pharmaceutical University, Japan.
Sugiyama
E
E
Taki
H
H
Kuroda
A
A
Yamashita
N
N
Maruyama
M
M
Kobayashi
M
M
D001172:Arthritis, Rheumatoid / Q000276:immunology / Q000378:metabolism*; D002273:Carcinogens / Q000494:pharmacology; D002478:Cells, Cultured; D015232:Dinoprostone / Q000494:pharmacology*; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000276:immunology; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology*; D017370:Interleukin-11 / Q000235:genetics* / Q000276:immunology; D007546:Isoquinolines / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology; D013449:Sulfonamides; D013583:Synovial Membrane / Q000166:cytology / Q000276:immunology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D002273:Carcinogens; D004791:Enzyme Inhibitors; D007211:Indoles; D007375:Interleukin-1; D017370:Interleukin-11; D007546:Isoquinolines; D008301:Maleimides; D013449:Sulfonamides; D014409:Tumor Necrosis Factor-alpha; D011493:Protein Kinase C; D015232:Dinoprostone; C070515:bisindolylmaleimide I; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; D013755:Tetradecanoylphorbol Acetate