The gut microbiota alteration and the key bacteria in Astragalus polysaccharides (APS)-improved osteoporosis

[Display omitted] •·Astragalus polysaccharides improve BMD and microarchitecture of osteoporotic bone.•·Astragalus polysaccharides induce structural and functional changes of gut microbiota.•·Changed gut microbiota is closely associated with the improvement of osteoporosis. Osteoporosis is a worldwide epidemic, and certain functional foods can alleviate osteoporosis with great efficiency. Here, in a dexamethasone-induced osteoporosis rat model, it was proved that APS could restore the bone mineral density (BMD) and repair the impairment of bone microarchitecture, two major features of osteoporosis. In APS-treated rats, acid phosphatase 5 (ACP5) and pro-inflammatory cytokines (TNF-α and IL-2) were significantly decreased. This suggested that APS might improve osteoporosis by inhibiting osteoclastogenesis and preventing inflammation. Further analysis on the bacterial community revealed that the structure of gut microbiota was dramatically changed by APS, and 13 bacteria (such as c_Bacteroidia, p_Bacteroidetes, and g_Allpprevotella) could serve as biomarkers for APS-improved osteoporosis. Furthermore, five genera (uncultured_bacterium_f_Ruminococcaceae, Alloprevotella, Ruminococcaceae_UCG-014, Blautia and Lactobacillus) were inferred as the key bacteria in APS-improved osteoporosis. In conclusion, APS-modified gut microbiota and the potential key bacteria to alleviate osteoporosis, as well as its relationship with improved osteoporosis, were investigated in our present study. Our results will help to understand how APS improves osteoporosis by regulating gut microbiota and contribute to the development and application of functional foods to alleviate refractory osteoporosis by regulating targeted intestinal bacteria.