Gualou-Xiebai-Banxia-Tang regulates liver-gut axis to ameliorate Metabolic Syndrome in HFD-fed mice

Metabolic syndrome (MetS), characterized by obesity, hyperglycemia, and abnormal blood lipid levels, is the pathological basis of many cardiovascular diseases. Gualou-Xiebai-Banxia-Tang decoction (GT) was first described in the Synopsis of the Golden Chamber, the earliest traditional Chinese medicine (TCM) monograph on diagnosis and treatment of miscellaneous diseases in China. According to TCM precepts, based on its ability to activate yang to release stagnation, activate qi to reduce depression, remove phlegm, and broaden the chest, GT has been used for more than 2,000 years to treat cardiovascular ailments. However, the molecular bases of its therapeutic mechanisms remain unclear.

The aim of this study was to identify lipid- and glucose-related hepatic genes differentially regulated by GT, and to assess GT impact on gut microbiota composition, in mice with high-fat diet (HFD)-induced MetS.

ApoE^-/^- mice were fed with an HFD for 24 weeks, with or without concurrent GT supplementation, to induce MetS. At the study's end, body weight, visceral fat weight, blood lipid levels, and insulin sensitivity were measured, and histopathological staining was used to evaluate hepatosteatosis and intestinal barrier integrity. Liver transcriptomics was used for analysis of differentially expressed genes in liver and prediction of relevant regulatory pathways. Hepatic lipid/glucose metabolism-related genes and proteins were detected by RT-qPCR and western blotting. Gut microbial composition was determined by 16S rRNA gene sequencing.

GT administration reduced MetS-related liver steatosis and weight gain, promoted insulin sensitivity and lipid metabolism, and beneficially modulated gut microbiota composition by decreasing the relative abundance of g_Lachnospiraceae_NK4A136_group and increasing the relative abundance of g_Alistipes. Liver transcriptomics revealed that GT regulated the expression of genes related to lipid and glucose metabolism (Pparγ, Igf1, Gpnmb, and Trem2) and of genes encoding chemokines/chemokine receptors (e.g. Cxcl9 and Cx3cr1). Significant, positive correlations were found for Ccr2, Ccl4, Ccr1, and Cx3cr1 and the g_Lachnospiraceae_NK4A136_group, and between Cxcl9, Ccr2, Ccl4, and Cx3cr1 and g_Desulfovibrio. GT treatment downregulated the protein expressions of SCD1 and CX3CR1 and upregulated the expression of PCK1 protein.

GT supplementation alleviates HFD-induced MetS in mice by improving hepatic lipid and glucose metabolism. The anti-metabolic syndrome effects of GT may be related to the regulation of the gut-liver axis.