Inhibition of Osteoclast Differentiation and Bone Resorption by N-Methylpyrrolidone

Abstract

Regulation of RANKL (receptor activator of nuclear factor B ligand)-induced osteoclast differentiation is of current interest in the development of antiresorptive agents. Osteoclasts are multinucleated cells that play a crucial role in bone resorption. In this study, we investigated the effects of N-methylpyrrolidone (NMP) on the regulation of RANKL-induced osteoclastogenesis. NMP inhibited RANKL-induced tartrate-resistant acid phosphatase activity and the formation of tartrate-resistant acid phosphatase-positive multinucleated cells. The RANKL-induced expression of NFATc1 (nuclear factor of activated T cells, cytoplasmic 1) and c-Fos, which are key transcription factors for osteoclastogenesis, was also reduced by treatment with NMP. Furthermore, NMP induced disruption of the actin rings and decreased the mRNAs of cathepsin K and MMP-9 (matrix metalloproteinase-9), both involved in bone resorption. Taken together, these results suggest that NMP inhibits osteoclast differentiation and attenuates bone resorption. Therefore, NMP could prove useful for the treatment of osteoporosis or other bone diseases associated with excessive bone resorption.Bone remodeling is a physiological process that involves the resorption and synthesis of bone by osteoclasts and osteoblasts, respectively (1, 2). Osteoclasts are known to be formed by the fusion of hematopoietic cells of the monocyte-macrophage lineage during the early stage of the differentiation process (3). This process consists of multiple steps, including differentiation of osteoclast precursors into mononuclear osteoclasts, fusion of mononuclear preosteoclasts into mature multinucleated osteoclasts, and activation of osteoclasts to resorb bone (4 -7). The terminal differentiation in this lineage is characterized by acquisition of mature phenotypic markers such as expression of tartrate-resistant acid phosphatase (TRAP), 2 the calcitonin receptor, MMP-9, and cathepsin K, as well as morphological conversion into large multinucleated cells and the ability to form resorption lacunae on bone (8 -10). The essential signaling molecules for osteoclast differentiation include RANKL and M-CSF (macrophage colony-stimulating factor) in bone marrow-derived macrophage precursor cells (11,12).RANKL is a member of the TNF superfamily that is expressed in osteoblasts. It interacts with the osteoclast cell surface receptor RANK, which in turn recruits TNF receptor-associated factors and plays a crucial role in the osteoclast differentiation axis (13,14). The downstream intracellular signaling mediated by RANK in osteoclast progenitor cells includes TRAF6 (TNF receptor-associated factor 6)-dependent activation of NF-B via the IB kinase complex and MAPKs such as ERK, p38 MAPK, and JNK (7,11,15). In addition, RANKL induces the key transcription factors for osteoclastogenesis, NFATc1 and c-Fos (9, 16, 17). Therefore, chemical or natural compounds that specifically inhibit these steps could be developed as antiresorptive drugs for the treatment of metabolic bone disorders characterized by e...

N‑methyl pyrrolidone promotes ankle fracture healing by inhibiting inflammation via suppression of the mitogen‑activated protein kinase signaling pathway

“…BK was reported to stimulate bone resorption in rats (11); thus 1 µM BK was used to generate an inflammatory model in the present study. Previous studies demonstrated that NMP enhances bone formation and inhibits osteoclast differentiation (15,16). Therefore, the present study investigated the effects of NMP on the BK-stimulated inflammatory response in MG-63 cells.…”

“…Previous studies have suggested that NMP may enhance bone formation and inhibit osteoclast differentiation (15,16). However, the molecular mechanism by which NMP exerts its anti-inflammatory function in MG-63 cells remains unresolved.…”

“…N-methyl pyrrolidone (NMP), a small bioactive molecule, enhances bone formation and inhibits osteoclast differentiation (15,16). It has been demonstrated that NMP inhibits inflammation by repressing the NF-kB pathway (17).…”

N-methyl pyrrolidone/bone morphogenetic protein-2 double delivery with in situ forming implants

“…NMP has been demonstrated to both increase bone forming activities of osteoblasts and decrease bone resorption of osteoclasts [10]. An in vivo study using a rabbit calvarial defect model showed significantly higher bone regeneration with NMP alone by increasing the activity of the natural locally deposited autologous BMP [9].…”

“…Instead of using the ISFI system to deliver a classical drug, we have explored this technology to extend the release of NMP, which itself is a bioactive substance [9,10]. By examining the dependence of the release profile on polymer properties, we have prolonged the release of NMP from hours to a few weeks.…”