Protective Effects of Fermented Oyster Extract against RANKL-Induced Osteoclastogenesis through Scavenging ROS Generation in RAW 264.7 Cells

Abstract

Excessive bone resorption by osteoclasts causes bone loss-related diseases and reactive oxygen species (ROS) act as second messengers in intercellular signaling pathways during osteoclast differentiation. In this study, we explored the protective effects of fermented oyster extract (FO) against receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclast differentiation in murine monocyte/macrophage RAW 264.7 cells. Our results showed that FO markedly inhibited RANKL-induced activation of tartrate-resistant acid phosphatase and formation of F-actin ring structure. Mechanistically, FO has been shown to down-regulate RANKL-induced expression of osteoclast-specific markers by blocking the nuclear translocation of NF-κB and the transcriptional activation of nuclear factor of activated T cells c1 (NFATc1) and c-Fos. Furthermore, FO markedly diminished ROS production by RANKL stimulation, which was associated with blocking the expression of nicotinamide adenine dinucleotide phosphate oxidase 1 (NOX1) and its regulatory subunit Rac-1. However, a small interfering RNA (siRNA) targeting NOX1 suppressed RANKL-induced expression of osteoclast-specific markers and production of ROS and attenuated osteoclast differentiation as in the FO treatment group. Collectively, our findings suggest that FO has anti-osteoclastogenic potential by inactivating the NF-κB-mediated NFATc1 and c-Fos signaling pathways and inhibiting ROS generation, followed by suppression of osteoclast-specific genes. Although further studies are needed to demonstrate efficacy in in vivo animal models, FO may be used as an effective alternative agent for the prevention and treatment of osteoclastogenic bone diseases.

Gamma Aminobutyric Acid-Enriched Fermented Oyster (Crassostrea gigas) Increases the Length of the Growth Plate on the Proximal Tibia Bone in Sprague-Dawley Rats

“…Numerous studies have demonstrated that GABA-enriched functional food have physiological benefits such as suppression of blood pressure [ 22 ], hepatoprotection [ 23 ], decrease in gut inflammation [ 24 ], and regulation of glucose tolerance [ 25 ]. Furthermore, several reports have demonstrated that GABA promoted bone health [ 15 , 16 , 26 , 27 , 28 ]. Watanabe et al [ 26 ] reported that GABA directly regulates the muscle tone, and Muhammad et al [ 27 ] suggested GABA promotes osteoblastogenesis by stimulation of bone formation genes.…”

“…Watanabe et al [ 26 ] reported that GABA directly regulates the muscle tone, and Muhammad et al [ 27 ] suggested GABA promotes osteoblastogenesis by stimulation of bone formation genes. More recently, Jeong et al [ 15 ] found that GABA-enriched seaweed suppressed osteoclastogenesis. Additionally, one study reported that peripheral GABA increases plasma GH concentration in humans [ 28 ].…”

“…Histochemical analysis of the longitudinal bone was performed using a previously described protocol with slight modifications [ 15 , 58 ]. Paraffin sections of the proximal tibia were dewaxed, rehydrated, and stained with hematoxylin and eosin (Sigma-Aldrich Chemical Co., St. Louis, MO, USA) and representative images were captured using a Leica DM 2500 (Leica Biosystems, Nussloch, Germany).…”

“…They also reported that peptides isolated from fermented oyster (FO) sauces possessed angiotensin-converting enzyme inhibitory activity, and oral administration of these peptides suppressed blood pressure in spontaneously hypertensive rats [ 11 ]. Recently accumulated evidence has established that FO is attributed to bone health [ 12 , 13 , 14 , 15 ]. Data published in 2019 demonstrated that FO prevented ovariectomy-induced bone loss and suppressed osteoclastogenesis [ 13 ].…”

“…A recent study reported that FO promotes bone formation by osteoblast differentiation via activating the Wnt/β-catenin signaling pathway in mouse pre-osteoblast MC3T3-E1 cells, human osteoblast-like MG-63 cells, and zebrafish larvae [ 14 ]. Our previous study suggested that FO attenuates osteoclastogenesis via suppression of reactive oxygen species in mouse macrophage cells [ 15 ]. We recently demonstrated that fermentation of oyster by Lactobacillus brevis BJ20 increased the amount of gamma aminobutyric acid (GABA), which may contribute to increased height in Sprague-Dawley (SD) rats [ 12 ].…”