Integrated 16S rRNA and metabolomics investigation of the hepatoprotective effects of Ixeris chinensis on high-fat diet-induced nonalcoholic fatty liver in mice

Abstract Ixeris chinensis (Thunb.) Nakai (IC) is traditionally used in Mongolian medicine prescriptions for liver diseases. This study aimed to investigate the hepatoprotective mechanism of IC on nonalcoholic fatty liver disease (NAFLD) mice by the integration of gut microbiota and metabolomics analysis. Male C57BL/6J mice were fed with chow or high-fat diet (HFD) with or without IC supplementation, and the gut microbial and metabolite profiles were studied by 16S rRNA sequencing and untargeted metabolomics, respectively. The results showed that the administration of IC resulted in significant decreases in body weight, liver index, serum biomarkers such as ALT, TG, and LDL-C, and the liver inflammatory factors IL-1β, IL-6, and TNF-α in mice fed with HFD. The 16S rRNA sequencing results showed that administration of the IC extract altered both the composition and abundance of the gut microbiota, thus leading to improvement of NAFLD. Untargeted metabolomics analysis of liver samples detected a total of 212 metabolites, of which 29 were differentially expressed. IC was found to significantly alter the levels of metabolites such as L-glutamic acid, pyridoxal, ornithine, L-aspartic acid, D-proline, and N4-acetylaminobutanal involved in the regulation of glutamine and glutamate, Vitamin B6 metabolism, and arginine and proline metabolism pathways. Correlation analysis indicated that the effects of the IC extract on metabolites were associated with alterations in the abundance of Akkermansiaceae, Lachnospiraceae, and Muribaculaceae. Our study revealed that IC has a potential hepatoprotective effect in NAFLD and that its function is linked to improvements in the composition of the gut microbiota and its metabolites.