Alleviation of high-fat diet-induced lipid metabolism disorders: role of quinoa peptides in reducing high-activity BSH-producing gut microbiota abundance and modulating BA-FXR/TGR5 signaling

INTRODUCTION: Lipid metabolism disorders contribute significantly to various metabolic diseases and are closely related to gut microbiota dysbiosis. Quinoa intake has been increasingly linked to improved metabolic regulation and body weight control. In our earlier work, oral administration of quinoa-derived peptides (QPep) modulated gut microbiota composition and mitigated hepatic lipid dysregulation in high-fat diet (HFD)-induced obese mice. Nevertheless, the specific mechanisms responsible for these effects remain incompletely understood. OBJECTIVES: This study aimed to elucidate the mechanisms by which QPep alleviates lipid metabolic disorders in HFD-induced obese mice. METHODS: Mice were fed a HFD with or without oral QPep intervention. Both antibiotic treatment and fecal microbiota transplantation were employed to assess the microbiota-dependent effects of QPep. Comprehensive multi-omics and molecular analyses were conducted to characterize metabolic phenotypes alongside gut microbial composition, bile acids (BAs) metabolism, and host signaling pathways in the liver, ileum, and adipose tissues. RESULTS: QPep administration alleviated HFD-induced metabolic disorders, leading to reductions in body weight and adiposity, improvements in serum lipid profiles and hepatic steatosis, and restoration of glucose homeostasis. Microbiota depletion and transplantation experiments suggested a microbiota-dependent contribution to the observed effects. Mechanistically, QPep selectively reduced high-activity bile salt hydrolase (BSH)-producing bacteria abundance, reduced intestinal BSH activity, and preserved conjugated BAs, thereby suppressing ileal FXR-FGF15 signaling, enhancing hepatic BAs synthesis, and activating TGR5 in adipose and ileum tissues to restore systemic lipid metabolism. CONCLUSION: These findings demonstrate that QPep modulate gut microbiota-BAs signaling to restore lipid homeostasis, highlighting their potential as a dietary intervention for the prevention and management of obesity-related metabolic disorders.