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Bacterial lipopolysaccharide induces osteoclast formation in RAW 264.7 macrophage cells.

Research paper by Shamima S Islam, Ferdaus F Hassan, Gantsetseg G Tumurkhuu, Jargalsaikhan J Dagvadorj, Naoki N Koide, Yoshikazu Y Naiki, Isamu I Mori, Tomoaki T Yoshida, Takashi T Yokochi

Indexed on: 29 Jun '07Published on: 29 Jun '07Published in: Biochemical and Biophysical Research Communications



Abstract

Lipopolysaccharide (LPS) is a potent bone resorbing factor. The effect of LPS on osteoclast formation was examined by using murine RAW 264.7 macrophage cells. LPS-induced the formation of multinucleated giant cells (MGC) in RAW 264.7 cells 3 days after the exposure. MGCs were positive for tartrate-resistant acid phosphatase (TRAP) activity. Further, MGC formed resorption pits on calcium-phosphate thin film that is a substrate for osteoclasts. Therefore, LPS was suggested to induce osteoclast formation in RAW 264.7 cells. LPS-induced osteoclast formation was abolished by anti-tumor necrosis factor (TNF)-alpha antibody, but not antibodies to macrophage-colony stimulating factor (M-CSF) and receptor activator of nuclear factor (NF)-kappaB ligand (RANKL). TNF-alpha might play a critical role in LPS-induced osteoclast formation in RAW 264.7 cells. Inhibitors of NF-kappaB and stress activated protein kinase (SAPK/JNK) prevented the LPS-induced osteoclast formation. The detailed mechanism of LPS-induced osteoclast formation is discussed.