Strontium chelate with Achyranthes bidentata polysaccharide as a carrier promotes bone regeneration through mediating the gut-liver-bone axis in TD chickens.

Abstract

BACKGROUND: Tibial dyschondroplasia (TD), characterized by impaired angiogenesis and abnormal chondrocyte maturation in the tibial growth plate (TGP), is a common bone disorder in commercial broilers. Strontium (Sr), a trace element with osteogenic and angiogenic properties that plays a crucial role in bone health, exhibits low bioavailability. Achyranthes bidentata polysaccharides, a major extract from Achyranthes bidentata with the function of "guiding the medicine downward", has been used to enhance drug delivery to the lower extremity meridians. PURPOSE: This study aimed to prepare a novel Achyranthes bidentata polysaccharides-strontium (ABPS-Sr) chelate to enhance Sr bioavailability and investigate its therapeutic effects on tibial damage in TD broilers from the perspective of the gut-bone axis. METHODS: The ABPS-Sr chelate was synthesized and optimized using response surface methodology, followed by structural characterization. A thiram-induced TD broiler model was established to evaluate the therapeutic efficacy of the ABPS-Sr chelate using qRT-PCR, Western blot, immunoprecipitation, micro-CT, histological staining, and biochemical assays. 16S rRNA sequencing and targeted and non-targeted metabolomics were employed to characterize alterations in gut microbiota, intestinal metabolites and plasma lipid metabolites. Experiments involving phosphatidylcholine (PC)-exposed broilers and fecal microbiota transplantation (FMT) in mice were performed to verify the mediate role of gut microbiota and tibia-damaging effects of PC. RESULTS: The one-pot synthesis of ABPS-Sr chelate was optimized to achieve a yield of 27.7 %, with structural characterization confirming Srcoordination-induced conformational changes and porous architecture. Dietary supplementation with ABPS-Sr chelate significantly improved growth performance, restored tibial microstructure, and promoted vessel density in the TGP in TD broilers. Moreover, ABPS-Sr chelate promoted angiogenesis in the TGP by upregulating VEGF expression and restored osteogenic differentiation by activating the ITGB1/FAK/PI3K/AKT1 signaling pathway. Furthermore, ABPS-Sr chelate reshaped gut microbiota composition, restored intestinal barrier function, and corrected hepatic lipid metabolism disorders, particularly by reducing plasma glycerophospholipid (e.g., PC) accumulation that exerts negative effects on bone health. CONCLUSION: This study demonstrated that ABPS-Sr chelate restores tibial injury in TD broilers by enhancing osteogenesis and angiogenesis via modulation of the gut-liver-bone axis, which provides a promising nutritional intervention strategy for improving poultry bone health.