The mechanism of bile acid metabolism regulating lipid metabolism and inflammatory response in T2DM through the gut-liver axis

Aims: The main objective of this study was to analyze the changes of intestinal microflora and how bile acid metabolic pathways affect lipid metabolism in T2DM through the gut-liver axis. Methods: Firstly, 16S rRNA sequencing, metabolomics and transcriptomic sequencing were performed on plasma and feces of clinical subjects to determine the changes of intestinal flora and its metabolites. Finally, T2DM mice model was verified in vivo. Results: T2DM patients have significant intestinal flora metabolism disorders. The differential fecal metabolites were mainly enriched in primary bile acid biosynthesis and cholesterol metabolism pathways in T2DM patients. After verification, the changes in gut microbiota and metabolites in T2DM patients (including up-regulated bacteria associated with BA metabolism, such as lactobacillus and bifidobacterial, and down-regulated bacteria capable of producing SCFAs such as Faecalibacterium, Bacteroides, Romboutsia and Roseburia); and the changes in the flora and metabolites that result in impairment of intestinal barrier function and changes of protein expression in the blood, intestine and liver of T2DM patients (including FGFR4 up arrow, TRPM5 up arrow and CYP27A1 down arrow, which are related to BA and lipid metabolism homeostasis, and TLR6 up arrow, MYD88 up arrow and NF-kappa B up arrow, which are related to inflammatory response). These aspects together contribute to the development of further disorders of glucolipid metabolism and systemic inflammation in T2DM patients. Conclusions: Changes in intestinal flora and its metabolites may affect lipid metabolism and systemic inflammatory response in T2DM patients through the gut-liver axis mediated by bile acids.