Inhibitory effects of Glossogyne tenuifolia and Crossostephium chinensis extracts on RANKL-induced osteoclast formation and their mechanisms

• Main Authors: Shih-Wei Wang, 王世緯
• Other Authors: Jer-Yiing Houng
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/pr6y6r

博士 === 義守大學 === 化學工程學系暨生物技術與化學工程研究所 === 102 === Bone destruction is a pathological hallmark of several diseases, including rheumatoid arthritis, osteoporosis, and metastatic bone cancer. Osteoclasts have been implicated to play a critical role in the pathogenesis of both localized bony erosion and diffuse bone loss. Osteoclasts, differentiated from hematopoietic myeloid precursor cells under regulation of specific cytokines and receptor signals, are specialized as the only bone-resorbing cell type and cause bone destruction. The receptor activator of nuclear factor-κB ligand (RANKL) plays a critical role in the differentiation, formation and activation of osteoclasts. Excessive RANKL signaling causes enhanced osteoclast formation and excess bone resorption and destruction. Therefore, down-regulation of RANKL expression or its downstream signals may be a promising approach to the treatment of pathological bone loss. Glossogyne tenuifolia (GT), originated in Penghu Islands, has a long history of using as an anti-inflammatory remedy in folk medicine. Crossostephium chinensis (CC) is also a special herb in Penghu Islands and Taiwan, which has been used to treat arthralgia and rheumatism. In our studies, based on the model of inducing the differentiation of RAW264.7 macrophages into osteoclasts by RANKL, the inhibitory effects of GT ethanol extract (GTE) and CC ethanol extract (CCE) on differentiation and formation of osteoclasts were evaluated. The inhibitory effect of CCE on the formation of RANKL-activated osteoclasts was further investigated by the model of peripheral blood mononuclear cells (PBMCs) from the patients with tophaceous gout. The research was approved by the Human Research Ethics Committee (No. EMRP-101-059 (RI)) and written informed consents were obtained from gouty patients before enrollment. The experimental results revealed that GTE was able to inhibit the RANKL-induced osteoclastogenesis. GTE significantly inhibited the RANKL-induced tartrate-resistance acid phosphatase (TRAP) activity and formation of multinucleated osteoclasts without cytotoxicity. GTE was shown to suppress osteoclast differentiation through reducing RANKL-induced nuclear factor of κB (NF-κB) activation and phosphorylation of mitogen-activated protein kinases (MAPKs) including c-Jun N-terminal kinases (JNK) and extracellular signal-regulated kinases (ERK). Additionally, with the exception of phosphoinositide 3-kinase (PI3K), the phosphorylated forms of osteoclast survival-related signaling molecules including NF-κB, JNK, p38 MAPK (p38), ERK, and protein kinases B (AKT) were decreased by GTE. In our study, CCE significantly inhibited the RANKL-induced formation of TRAP-positive multinucleated osteoclasts in a dose-dependent manner. CCE suppressed RANKL-induced osteoclast differentiation via down-regulating activation of tumor-necrosis factor receptor-associated factor 6 (TRAF6), NF-κB and MAPKs, including ERK, JNK and p38, and the expression of nuclear factor of activated T cells, cytoplasmic 1 (NFATc1) and matrix metalloproteinase 9 (MMP-9). Additionally, CCE inhibited pit formation on Osteo Assay Surface system in a dose-dependent manner that indicated its ability to inhibit the bone resorptive activity of mature osteoclasts in a RAW264.7 cells model. Moreover, CCE suppressed RANKL-induced differentiation of osteoclasts in PBMCs from patients with tophaceous gout. CCE also decreased bone resorptive activity of mature osteoclasts differentiated in PBMCs. Taken together, our findings clearly show that GTE and CCE can attenuate RANKL-induced differentiation and formation of osteoclasts. Thus, GTE and CCE have a potential to become complementary agents for treating various bone diseases associated with excessive osteoclast formation and bone destruction.