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Updated: Jul 14, 2026
Bone Marrow-derived Macrophage Production
Published on: November 22, 2013
Bacterial lipopolysaccharide induces osteoclast formation in RAW 264.7 macrophage cells
Shamima Islam1, Ferdaus Hassan, Gantsetseg Tumurkhuu
1Department of Microbiology and Immunology, Aichi Medical University School of Medicine, Nagakute, Aichi 480-1195, Japan.
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.
Insights
Lipopolysaccharide (LPS) triggers bone-resorbing osteoclast formation in macrophage cells. Tumor necrosis factor-alpha (TNF-alpha) plays a key role in this LPS-induced process.
Area of Science:
- Immunology
- Cell Biology
- Bone Biology
Background:
- Lipopolysaccharide (LPS) is a known potent stimulator of bone resorption.
- Osteoclasts are critical cells responsible for bone breakdown.
Purpose of the Study:
- To investigate the effect of LPS on osteoclast formation using RAW 264.7 macrophage cells.
- To elucidate the molecular mechanisms underlying LPS-induced osteoclastogenesis.
Main Methods:
- Murine RAW 264.7 macrophage cells were exposed to LPS.
- Osteoclast differentiation was assessed by multinucleated giant cell (MGC) formation, tartrate-resistant acid phosphatase (TRAP) activity, and resorption pit assays.
- The role of specific cytokines and signaling pathways was examined using antibodies and inhibitors.
Main Results:
- LPS exposure induced the formation of TRAP-positive MGCs in RAW 264.7 cells, which formed resorption pits.
- LPS-induced osteoclast formation was inhibited by anti-tumor necrosis factor-alpha (TNF-alpha) antibody, but not by antibodies against M-CSF or RANKL.
- Inhibitors of NF-kappaB and SAPK/JNK pathways blocked LPS-induced osteoclast formation.
Conclusions:
- LPS effectively induces osteoclast formation in RAW 264.7 cells.
- TNF-alpha is a critical mediator in LPS-induced osteoclastogenesis.
- The NF-kappaB and SAPK/JNK signaling pathways are involved in the mechanism of LPS-induced osteoclast formation.
