Jiangu granule ameliorated OVX rats bone loss by modulating gut microbiota-SCFAs-Treg/Th17 axis.

Background: Postmenopausal osteoporosis (PMOP) is a common disease that has decreased bone strength as its main symptom after menopause. Effective treatment for PMOP remains lacking, but traditional Chinese medicine has some advantages in delaying bone loss. Jiangu granule is a traditional Chinese medicine prescription commonly used to treat PMOP. Previous studies have demonstrated its efficacy, but the mechanism of action remains uncharacterized.

Purpose: This study aims to observe and discuss the mechanism of Jiangu granule to ameliorate bone loss in OVX rats by regulating the gut microbiota (GM)-short-chain fatty acids (SCFAs)- Treg/Th17 axis.

Methods: Female SD rats were divided into the sham operation (S), Jiangu granule (J), and model group (M). Bilateral ovaries were surgically removed from the rats in the J and M groups. After 6 and 12 weeks, rats were sacrificed, and femur, tibia, vertebrae, serum, spleen, colon, and feces samples were collected. We detected the strength of bones, gut microbiota structure, and SCFAs in feces, the Treg and Th17 cell levels in the spleen, and cytokine levels in the serum.

Result: Jiangu granule restored the abundance of gut microbiota, increased the content of SCFAs, reduced the permeability of colon epithelium, increased the proportion of Treg cells in the spleen, changed the osteoimmunomodulation-related cytokines, effectively prevented bone loss, and enhanced bone strength.

Conclusion: Jiangu granule can effectively improve bone loss in OVX rats, possibly by regulating the "GM-SCFAs-Treg/Th17″ axis.