Gusongan capsule enhances osteogenic differentiation to mitigate bone loss in ovariectomized rats via the TLR2/NF-κB pathway.

BACKGROUND

Osteoporosis (OP) is a metabolic bone disease characterized by reduced bone mass and impaired bone microstructure, leading to an increased risk of fractures. In this context, the Gusongan (GSA) capsule has gained recognition for its osteogenic potential.

PURPOSE: This study sought to examine the therapeutic effects of GSA capsule on OP and to elucidate the molecular mechanisms underpinning its osteoprotective properties.

METHODS

An OP model was established in female Sprague-Dawley rats through bilateral ovariectomy (OVX), followed by gavage administration of varying doses of GSA capsule. The study included the control, OVX model, and positive control (alendronate) groups. Bone mineral density (BMD) and serum biomarkers of rats were analyzed using micro-computed tomography (micro-CT) and enzyme-linked immunosorbent assay (ELISA). RNA sequencing (RNA-seq)- and network pharmacology-based analyses were conducted to identify potential molecular targets. Additionally, in vitro experiments were performed to evaluate the impacts of GSA capsule on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and the TLR2/NF-κB pathway.

RESULTS

Micro-CT analysis demonstrated that GSA capsule treatment markedly improved BMD, trabecular number (Tb.N), and bone volume/total volume (BV/TV), while reducing trabecular separation (Tb.Sp) (p< 0.05). ELISA results further revealed that GSA capsule diminished serum levels of bone Gla protein (BGP), bone alkaline phosphatase (BALP), and tartrate-resistant acid phosphatase (TRACP) in OVX rats (p< 0.05), suggesting an inhibitory effect on bone resorption and turnover. RNA-seq- and network pharmacology-based analyses highlighted the downregulation of key factors in the TLR2/NF-κB pathway in BMSCs following GSA capsule treatment. Furthermore, GSA capsule enhanced BALP activity and mineralized nodule formation in BMSCs (p< 0.05). In vitro investigations corroborated that GSA capsule downregulated TLR2 and NF-κB p65 levels and fostered the expression of osteogenic genes, including COL1A1, RUNX2, and OPN (p< 0.05).

CONCLUSION

This study highlighted that GSA capsule attenuated inflammation and augmented osteogenic differentiation of BMSCs by targeting the TLR2/NF-κB pathway. These molecular mechanisms contributed to enhanced BMD and bone microarchitecture in OVX rats, suggesting the therapeutic potential of GSA capsule in OP management.