Abstract
As the society is aging, the increasing prevalence of osteoporosis has generated huge social and economic impact, while the drug therapy for osteoporosis is limited due to multiple targets involved in this disease. Zhuangguguanjie formulation (ZG) is extensively used in the clinical treatment of bone and joint diseases, but the underlying mechanism has not been fully described. This study aimed to examine the therapeutic effect and potential mechanism of ZG on postmenopausal osteoporosis. The ovariectomized (OVX) mice were treated with normal saline or ZG for 4 weeks after ovariectomy following a series of analyses. The bone mass density (BMD) and trabecular parameters were examined by micro-CT. Bone remodeling was evaluated by the bone histomorphometry analysis and ELISA assay of bone turnover biomarkers in serum. The possible drug–disease common targets were analyzed by network pharmacology. To predict the potential biological processes and related pathways, GO/KEGG enrichment analysis was performed. The effects of ZG on the differentiation phenotype of osteoclasts and osteoblasts and the predicted pathway were verified in vitro. The results showed that ZG significantly improved the bone mass and micro-trabecular architecture in OVX mice compared with untreated OVX mice. ZG could promote bone formation and inhibit bone resorption to ameliorate ovariectomy-induced osteoporosis as evidenced by increased number of osteoblast (N.Ob/Tb.Pm) and decreased number of osteoclast (N.Oc/Tb.Pm) in treated group compared with untreated OVX mice. After identifying potential drug–disease common targets by network pharmacology, GO enrichment analysis predicted that ZG might affect various biological processes including osteoblastic differentiation and osteoclast differentiation. The KEGG enrichment analysis suggested that PI3K/Akt and mTOR signaling pathways could be the possible pathways. Furthermore, the experiments in vitro validated our findings. ZG significantly down-regulated the expression of osteoclast differentiation markers, reduced osteoclastic resorption, and inhibited the phosphorylation of PI3K/Akt, while ZG obviously up-regulated the expression of osteogenic biomarkers, promoted the formation of calcium nodules, and hampered the phosphorylation of 70S6K1/mTOR, which can be reversed by the corresponding pathway activator. Thus, our study suggested that ZG could inhibit the PI3K/Akt signaling pathway to reduce osteoclastic bone resorption as well as hamper the mTORC1/S6K1 signaling pathway to promote osteoblastic bone formation.
Highlights
Osteoporosis has been defined as a systemic skeletal disease characterized by reduced bone mineral density and microarchitecture deterioration (Weitzmann and Ofotokun, 2016), with an increase in susceptibility to fractures (Fuggle et al, 2019)
To validate the Mammalian target of rapamycin (mTOR) signaling pathway as the potential mechanism for ZG action on osteoblasts predicted by network pharmacology, we examined the changes of protein levels of p-mTOR and p-70S6K1 in preosteoblast during ZG treatment by western blot
We demonstrated that MHY1485 supplement obviously attenuated the expression levels of osteogenic genes (Figure 4E), the ALP activity (Figures 4F,H), and the capability of extracellular matrix mineralization (Figures 4G,I) in osteoblasts treated with ZG, whereas depressed the protein levels of p-mTOR and p-70S6K1 in osteoblasts treated with ZG (Figure 4J)
Summary
Osteoporosis has been defined as a systemic skeletal disease characterized by reduced bone mineral density and microarchitecture deterioration (Weitzmann and Ofotokun, 2016), with an increase in susceptibility to fractures (Fuggle et al, 2019). The search for anti-osteoporosis medications still remains a challenge. Standard antiresorptive therapeutic schedules for osteoporosis mainly include bisphosphonate and estrogen replacement therapy (Gatti and Fassio, 2019) and were restricted by single target and adverse effects (Khosla and Hofbauer, 2017). Anabolic therapies have been approved to protect osteoporosis via facilitating bone formation alone or with antiresorptive agents (Estell and Rosen, 2021). There is no proposed curative treatment for osteoporosis that could simultaneously inhibit bone resorption and promote bone formation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
