基于肠道菌群代谢产物短链脂肪酸驱动骨髓免疫微环境探讨女贞子抗骨质疏松的分子机制和物质基础

骨质疏松发病率逐年升高，亟需发现新的干预措施。短链脂肪酸（SCFAs）通过其受体GPR43驱动骨髓微免疫环境影响Wnt和RANKL信号，已成为骨质疏松研究的热点。我们前期研究表明，女贞子既能提高肠源性SCFAs含量，又能调节Wnt和RANKL信号，抑制骨质疏松骨丢失，但这种作用是否与SCFAs相关尚未知。为此，本项目提出“女贞子通过肠源性SCFAs驱动骨髓免疫微环境而促进骨形成和抑制骨吸收从而抗骨质疏松”假说。我们拟利用μCT、FTIR、qPCR、FACS、能量代谢仪、电镜和气相色谱等技术，研究女贞子促进去卵巢小鼠SCFAs生成有效组分及其抗骨质疏松作用，探索其通过SCFAs/GPR43调节Treg和Th17细胞分化而激活Wnt信号促进骨形成，抑制TNFα/RANKL信号而降低骨吸收，揭示女贞子通过SCFAs驱动骨髓免疫微环境而抗骨质疏松的分子机制和物质基础，为其临床应用提供实验依据。

New interventions are needed to reduce the risk for osteoporosis. It was demonstrated that short-chain fat acids (SCFAs) contribute to bone remodeling through the regulation of Wnt and RANKL signaling via bone marrow immune microenvironment by G protein-coupled receptor 43 (GPR43), which gained increasing attention in prevention against osteoporosis. We have previously demonstrated that, Fructus Ligustri Lucidi (FLL) affects osteoporosis-induced bone loss not only through promoting SCFAs production, but also facilitating bone formation via promotion of Wnt signaling, and reducing bone absorption via inhibition of RANKL signaling, However, whether FLL preserves bone quality through the regulation of gut microbiota derived-SCFAs still remains unclear. Therefore, we hypothesize that the anti-osteoporotic activity of FLL acts through the promotion of bone formation and inhibition of bone resorption via the regulation of bone marrow immune microenvironment by gut microbiota-derived-SCFAs. To this end, micro-CT, Fourier-transform infrared spectroscopy (FTIR), real-time PCR, confocal microscope, fluorescence-activated cell sorting (FACS), Seahorse, immunohistochemistry, electron microscope and Gas chromatography-mass spectrometry (GC/MS) will be employed. We will investigate: (1) the anti-osteoporotic effect of FLL active constituents that promotes SCFAs production in ovariectomized (OVX) mice; (2) the actions of SCFAs on osteoblastic bone formation and osteoclastic bone resorption through the regulation of Wnt and TNFα/RANKL signaling via modulation of Treg and Th17 cells differentiation by GPR43. All the experiments will contribute to reveal the molecular mechanism of FLL in improving bone quantity and quality through the regulation of gut microbiota-derived-SCFAs via bone immune microenvironment. Our results will provide the scientific evidence for clinical application of this herb to management of the osteoporotic patients.