Yougui pills prevent ovariectomy-induced bone loss by suppressing Th17 response and IL-17/NF-κB pathway

Osteoporosis is a chronic metabolic bone disease that causes excessive osteoclast formation, ultimately resulting in massive bone loss. Yougui pills (YGPs) are the classic traditional Chinese medicine formula with an anti-osteoporosis effect, but the underlying mechanisms are unknown.

The ameliorative impact of YGPs on bone loss in ovarectomized mice model was examined by Alcian Blue Haematoxylin (ABH) staining and micro-CT scanning. The "YGPs-osteoporosis-target" network was established and analyzed to explore the molecular mechanism of YGPs on osteoporosis. In addition, flow cytometry and immunohistochemistry (IHC) were used to detect the Th17 response and the expression levels of CD4, IL-17A, RANKL, and RORγt. Finally, we examined the expressions of p-P65, nuclear factor of activated T cells 1 (NFATc1), and cathepsin K (CTSK) by IHC and immunofluorescence (IF) staining to investigate the inhibitory effects of YGPs on osteoclast formation and function in vitro and in vivo.

The results of ABH staining and micro-CT scanning showed that YGPs can significantly prevent bone loss. The 'YGPs-osteoporosis-target' network found that IL-17 is the key target, and its effects may be closely related to the upstream Th17 cells and the downstream NF-κB pathway of IL-17. Meanwhile, Th17 response and the expression levels of CD4, IL-17A, RANKL, and RORγt increased in the OVX group compared with the sham group, while YGPs treatment significantly reduced the above conditions. We also found that the number and function of osteoclasts (OCs) were significantly increased by incubation with IL-17, while YGPs treatment inhibited osteoclast formation and function. Furthermore, YGPs can suppress the expression of p-P65, NFATc1, and CTSK by IHC and IF staining in vitro and in vivo.

YGPs can exert anti-osteoporosis effects by regulating osteoimmunity, and the mechanism is to inhibit osteoclast formation and bone loss by suppressing the Th17 response and IL-17/NF-κB pathway.