CXCL2 has been known to regulate immune functions mainly by chemo-attracting neutrophils. In this study, we show that CXCL2 can be induced by receptor activator of NF-kappaB ligand, the osteoclast (OC) differentiation factor, through JNK and NF-kappaB signaling pathways in OC precursor cells. CXCL2 in turn enhanced the proliferation of OC precursor cells of bone marrow-derived macrophages (BMMs...

Receptor activator of NF-κB ligand (RANKL)-induced osteoclastogenesis is accompanied by intracellular Ca(2+) mobilization in a form of oscillations, which plays essential roles by activating sequentially Ca(2+)/calmodulin-dependent protein kinase, calcineurin and NFATc1, necessary in the osteoclast differentiation. However, it is not known whether Ca(2+) mobilization which is evoked in RANKL-in...

Inflammatory responses are frequently associated with the expression of inflammatory cytokines and severe osteoclastogenesis, which significantly affect the efficacy of biomaterials. Recent findings have suggested that interferon (IFN)-γ and zoledronate (Zol) are effective inhibitors of osteoclastogenesis. However, little is known regarding the utility of IFN-γ and Zol in bone tissue engineerin...

Pim kinases are emerging as important mediators of cytokine signaling pathways in hematopoietic cells. In this study, we demonstrate that Pim-1 positively regulates RANKL-induced osteoclastogenesis and that Pim-1 expression can be upregulated by RANKL signaling during osteoclast differentiation. The silencing of Pim-1 by RNA interference or overexpression of a dominant negative form of Pim-1 (P...

Interleukin (IL)-6 is known to indirectly enhance osteoclast formation by promoting receptor activator of nuclear factor kappa-B ligand (RANKL) production by osteoblastic/stromal cells. However, little is known about the direct effect of IL-6 on osteoclastogenesis. Here, we determined the direct effects of IL-6 and its soluble receptor (sIL-6R) on RANKL-induced osteoclast formation by osteoclas...

BACKGROUND Osteomyelitis is one of the refractory diseases encountered in orthopedics, while Staphylococcus aureus (S. aureus) is the most common causative organism in osteomyelitis. However, the precise mechanisms underlying the bone loss caused by S. aureus infection have not been well defined. Here, we investigated the effect of S. aureus on osteoclast differentiation and the probable molecu...

BACKGROUND Toll-like receptor 4 (TLR4) has been implicated in inflammation-induced bone destruction in various chronic bone diseases; however, its direct influence on bone healing is not well understood. The authors' previous study showed accelerated bone healing with higher osteoclastogenesis gene expression in toll-like receptor 4 knockout mice (TLR4). This study aimed to further elucidate th...

Osteoclasts are large multinucleated cells responsible for bone resorption. Excessive inflammatory activation of osteoclasts leads to bony erosions, which are the hallmark of several diseases such as rheumatoid arthritis (RA). Salt-inducible kinases (SIK) constitute a subfamily of kinases comprising three members (SIK1, -2, and -3). Inhibition of SIK kinase activity induces an anti-inflammatory...