Gut microbiota and short-chain fatty acids signatures in postmenopausal osteoporosis patients: A retrospective study

Studies have shown that gut microbiota (GM) and its metabolites, short-chain fatty acids (SCFAs), are associated with the development of postmenopausal osteoporosis (PMO). This study explored the clinical and laboratory evidence of the relationship of GM and SCFAs to PMO and attempted to determine the potential mechanism of action. 18 patients (Collected from the First Affiliated Hospital of Guangdong Pharmaceutical University between January 2021 and August 2021) were included in this retrospective study, including 10 PMO women and 8 healthy young women as the healthy control (HC) group from Guangzhou, China. Bone mineral density (BMD) was determined by dual-energy X-ray absorptiometry. The composition of GM and its metabolites, SCFAs, in the fecal samples were measured by 16S rRNA gene sequencing and gas chromatography/mass spectrometry analysis, respectively. Compared with healthy control, PMO group had significantly decreased BMD in lumbar spines 1-4 (BMD_L) and femoral neck (BMD_F). 16S rRNA gene sequencing revealed that, compared with healthy control, PMO group had a markedly decreased abundance in Subdoligranulum, Norank_f_Muribaculaceae, and Alistipes at the genus level. Gas chromatography/mass spectrometry analysis indicated that the concentration of propanoic acid significantly dropped in PMO group. Additionally, we found that Subdoligranulum, Norank_f_Muribaculaceae, and Alistipes were positively correlated with BMD_L. Subdoligranulum and Norank_f_Muribaculaceae were also positively correlated BMD_F and propanoic acid, while Subdoligranulum is the only species that presented a strong correlation with the levels of acetic acid and butyric acid. Our findings indicated that, in postmenopausal women, there were evident changes in GM and SCFAs, and these changes were found correlated with patients' BMD. These correlations provide novel insights into the underlying mechanism of PMO development, representative of early diagnostic markers and therapeutic targets that may improve the bone health in postmenopausal women.