Obesity, but not high-fat diet, is associated with bone loss that is reversed via CD4+CD25+Foxp3+ Tregs-mediated gut microbiome of non-obese mice.

Osteoporosis is characterized by decreased bone mass, microarchitectural deterioration, and increased bone fragility. High-fat diet (HFD)-induced obesity also results in bone loss, which is associated with an imbalanced gut microbiome. However, whether HFD-induced obesity or HFD itself promotes osteoclastogenesis and consequent bone loss remains unclear. In this study, we developed HFD-induced obesity (HIO) and non-obesity (NO) mouse models to evaluate the effect of HFD on bone loss. NO mice were defined as body weight within 5% of higher or lower than that of chow diet fed mice after 10 weeks HFD feeding. NO was protected from HIO-induced bone loss by the RANKL /OPG system, with associated increases in the tibia tenacity, cortical bone mean density, bone volume of cancellous bone, and trabecular number. This led to increased bone strength and improved bone microstructure via the microbiome-short-chain fatty acids (SCFAs) regulation. Additionally, endogenous gut-SCFAs produced by the NO mice activated free fatty acid receptor 2 and inhibited histone deacetylases, resulting in the promotion of Treg cell proliferation in the HFD-fed NO mice; thereby, inhibiting osteoclastogenesis, which can be transplanted by fecal microbiome. Furthermore, T cells from NO mice retain differentiation of osteoclast precursors of RAW 264.7 macrophages ex vivo. Our data reveal that HFD is not a deleterious diet; however, the induction of obesity serves as a key trigger of bone loss that can be blocked by a NO mouse-specific gut microbiome.

Optimization of the ultrafiltration-assisted extraction of Chinese yam polysaccharide using response surface methodology and its biological activity.

Ultrafiltration is a separation process for purifying and concentrating macromolecular solutions. Using Baiyu yam (Dioscorea opposita Thunb) as the raw material, single-factor experiments, Box-Behnken design (BBD) and response surface methodology (RSM) were employed to investigate the effects of the ultrafiltration pH, temperature and pressure on the extraction rate of Chinese yam polysaccharide (CYP). The constructed regression model is highly significant, and the optimal ultrafiltration-assisted extraction conditions were determined to be the following: pH 6.5, 20 °C and 0.03 MPa. Under these optimal conditions, a CYP extraction rate of 88.7% was achieved. After purification with anion exchange (DE-52) and size-exclusion (Sephadex G-100) columns, the monosaccharide composition of CYP was determined to be 50.8% glucose, 24.2% mannose and 11.8% galactose. Fourier transform infrared (FT-IR) spectroscopy characterization of CYP confirmed the characteristic absorption peaks of the polysaccharides. The microstructure of CYP exhibited characteristics typical of amorphous powders. CYP also exhibited antioxidant activities, including the scavenging of DPPH radicals, hydroxyl radicals and superoxide anion radicals. Moreover, CYP exhibited a relatively strong inhibitory effect on BGC-823 cell growth.