Enhancing Akkermansia growth via phytohormones: a strategy to modulate the gut-bone axis in postmenopausal osteoporosis therapy.

Background: Phytohormones have garnered considerable interest as potential modulators of the gut-bone axis. Denosumab (Deno), a widely utilized therapeutic agent for postmenopausal osteoporosis, has not been previously investigated for its effects on gut health. The objective of this study was to assess the efficacy of isoflavones (SI), naringin (Nar), and Deno in the management of postmenopausal osteoporosis by targeting the gut-bone axis.

Methods: The postmenopausal osteoporosis model in mice was established via bilateral oophorectomy. Subsequently, mice in the Deno group received subcutaneous injections of Deno at a dosage of 10 mg/kg, administered twice weekly. In contrast, mice in the SI and Nar groups were subjected to oral gavage with 200 mg/kg/day of SI and Nar, respectively. The treatment period for all groups lasted for 8 weeks. Upon the conclusion of the experiment, a thorough evaluation of the effects of SI, Nar, and Deno on bone and gut health in mice was conducted through immunological, pathological, imaging, and multi-omics methodologies.

Results: Deno, SI, and Nar significantly alleviated the physical symptoms in postmenopausal mice. However, only SI and Nar significantly modulated the gut microbiota. Akkermansia was significantly enriched after the gavage of SI and Nar. Akkermansia has the capacity to not only augment bone mass and alleviate strength deterioration via extracellular vesicles, but it also influences bone metabolism by diminishing inflammation and modulating lipid metabolism. Notably, no significant changes in the gut microbiota were observed in the Deno group, which may be attributed to the differences in the method of administration, as Deno was administered via subcutaneous injection rather than gavage.

Conclusion: SI and Nar may influence the gut-bone axis through Akkermansia and have the potential of alternative treatment options for postmenopausal osteoporosis. Although the gut microbiota is not significantly affected by the subcutaneous administration of Deno, the long-term management of postmenopausal osteoporosis and the exploration of various management models warrant additional scrutiny. Furthermore, this study has yet to establish a dose-response relationship, indicating that further research is essential to clarify the regulatory effects of varying doses of SI and Nar on postmenopausal osteoporosis especially the modulation of gut microbiota.