Methotrexate suppresses inflammatory agonist induced interleukin 6 synthesis in osteoblasts.
OBJECTIVE
Interleukin 6 (IL-6) is a pleiotropic cytokine that plays a crucial role in the pathogenesis of rheumatoid arthritis (RA). In bone metabolism, it is known that IL-6 is produced and secreted by osteoblasts, and that IL-6 induces osteoclast formation and stimulates bone resorption. Various bone inflammatory agonists such as tumor necrosis factor-alpha (TNF-alpha), IL-1alpha, prostaglandin D2 (PGD2), PGE2, and PGF2alpha, which play important roles in the pathogenesis of RA, induce IL-6 synthesis in osteoblast-like MC3T3-E1 cells. Low dose methotrexate (MTX) is currently used for treatment of patients with RA. We investigated the effect of MTX on IL-6 synthesis induced by these agents in MC3T3-E1 cells.


METHODS
Cultured cells were pretreated with various doses of MTX, and then stimulated by these inflammatory agonists. The IL-6 in the conditioned medium was measured by IL-6 enzyme immunoassay.


RESULTS
MTX significantly suppressed IL-6 synthesis stimulated by these agonists in a dose-dependent manner, although MTX alone had no effect on the levels of IL-6. In addition, MTX significantly inhibited the enhancement by IL-17 of TNF-alpha-stimulated IL-6 synthesis. MTX reduced the levels of IL-6 induced by 12-O-tetradecanoylphorbol 13-acetate, a direct activator of protein kinase C (PKC), suggesting that MTX inhibits PKC signals for IL-6 synthesis.


CONCLUSIONS
MTX suppresses IL-6 synthesis stimulated by various inflammatory agonists in osteoblasts.
Yoshida
Minoru
M
Department of Pharmacology, Gifu University Graduate School of Medicine, Gifu, Japan.
Kanno
Yosuke
Y
Ishisaki
Akira
A
Tokuda
Haruhiko
H
Hirade
Kouseki
K
Nakajima
Keiichi
K
Katagiri
Yoshihiro
Y
Shimizu
Katsuji
K
Kozawa
Osamu
O
D016475:3T3 Cells; D000818:Animals; D018501:Antirheumatic Agents / Q000494:pharmacology*; D002273:Carcinogens / Q000494:pharmacology; D002478:Cells, Cultured; D015237:Dinoprost / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology; D004347:Drug Interactions; D007375:Interleukin-1 / Q000494:pharmacology; D020381:Interleukin-17 / Q000494:pharmacology; D015850:Interleukin-6 / Q000378:metabolism*; D008727:Methotrexate / Q000494:pharmacology*; D051379:Mice; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D015230:Prostaglandin D2 / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D018501:Antirheumatic Agents; D002273:Carcinogens; D007375:Interleukin-1; D020381:Interleukin-17; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D042461:Vascular Endothelial Growth Factor A; D015237:Dinoprost; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate; D015230:Prostaglandin D2; D008727:Methotrexate