Integrity of gut barrier is the foundation of the multiple function of intestinal tract to keep normal.Dietary conditionally essential amino acids are major fuels for the small intestinal mucosa as well as important substrates for syntheses of intestinal proteins,nitric oxide and metabolic products,and are required for maintaining intestinal integrity.The article reviewed recent advances in dietary uses of functional amino acids(including glutamine,glutamate,and arginine) to enhance the gut health and immune status of animals.

Objective: To provide the mechanism-based pharmacotherapy of the Huatan Qushi formula (HTQS formula), for the health management and treatment of non-alcoholic fatty liver disease (NAFLD). Methods: A rat model of NAFLD was employed to examine the efficacy and safety of the HTQS formula. In vivo active components and potential mechanisms of the HTQS formula were identified using UPLC‒MS/MS combined with network pharmacology. The influence of the HTQS formula on the dominating proteins in PI3K/Akt pathway was validated in vivo using western blot. Finally, 16S rRNA sequencing of the gut microbiome was conducted followed by targeted metabolomics detecting fecal short-chain fatty acids (SCFAs) and bile acids to determine the impact of the HTQS formula on gut microbiota. Results: The HTQS formula reduced weight gain and hepatic steatosis in NAFLD rats and decreased serum total cholesterol (TC), triglycerides, blood glucose, and insulin resistance (IR) without causing liver or kidney injury. We detected 28 components using UPLC‒MS/MS and identified 439 shared targets between NAFLD and the HTQS formula. Primarily, we focused on the PI3K/Akt signaling pathway based on protein‒protein interaction network analysis. We validated that the HTQS formula inhibited liver steatosis and inflammation by increasing the phosphorylation levels of PI3K, AKT, P27, GSK3β in the PI3K/Akt signaling pathway. 16S rRNA sequencing revealed that the HTQS formula reduced the abundance of the genus Family_XIII_AD3011_group, which was positively correlated with IR and taurodeoxycholic acid. In addition, Lachnospiraceae_UCG_010 inversely correlated with TC and five bile acids, which could be essential to the therapeutic effect of the HTQS formula against NAFLD. Conclusions The HTQS formula proved to be an effective pharmacotherapy for NAFLD without causing liver or kidney injury. Multiple potent components of the HTQS formula could alleviate liver steatosis and lipid metabolism disorder by modulating the PI3K/Akt signaling pathway and restoring gut microbiota composition.