Therapeutic Mechanisms of Medicine and Food Homology Formula Xiao-Ke-Yin on Glucolipid Metabolic Dysfunction Revealed by Transcriptomics, Metabolomics and Microbiomics in mice
Authors: Li Mei , Cheng Ding , Peng Chuan , Huang Yujiao , Geng Jie , Huang Guangrui , Wang Ting , Xu Anlong 
Published: January 2023

Abstract
Background: In the past decades, the prevalence of metabolic diseases, particularly diabetes, hyperlipidemia, obesity, non-alcoholic fatty liver disease (NAFLD), has increased dramatically, thereby causing great public health and economic burden worldwide. Traditional Chinese Medicine (TCM) served as an effective therapeutic choice. Xiao-Ke-Yin (XKY) is a medicine and food homology TCM formula consisted of nine “medicine and food homology” herbs, which was used to ameliorate metabolic diseases, such as insulin resistance, diabetes, hyperlipidemia and non-alcoholic fatty liver disease. However, despite its therapeutic potential on metabolic disorders, the underlying mechanisms remain unclear. This study aimsto evaluate the therapeuticeffectiveness of XKY on glucolipid metabolism dysfunction, and explored the potential mechanisms in db/db mice.
Methods: To verify the effects of XKY, db/db mice were treated with different concentrations of XKY (5.2, 2.6 and 1.3 g/kg/d) and Metformin (0.2 g/kg/d, a hypoglycemic positive control) for 6 weeks, respectively. During this study, we detected the body weight (BW) and fasting blood glucose (FBG), oral glucose tolerance test (OGTT), insulin tolerance test (ITT), daily food intake and water intake. At the end of the animal experiment, blood samples, feces, livers and intestine tissues of mice in all groups were collected. The potential mechanisms were investigated by using hepatic RNA sequencing, 16S rRNA sequencing of gut microbiota and metabolomics analysis.
Results: XKY efficiently mitigated hyperglycemia, IR, hyperlipidemia, inflammation and hepatic pathological injury in a dose dependent manner. Mechanistically, hepatic transcriptomic analysis showed that XKY treatment significantly reversed the upregulated cholesterol biosynthesis which was further confirmed by RT-qPCR. Additionally, XKY administration maintained intestinal epithelial homeostasis, modulated gut microbiota dysbiosis, and regulated its metabolites. In particular, XKY decreased secondary bile acid producing bacteria (Clostridiaand Lachnospircaeae) and lowered fecal secondary bile acid (lithocholic acid (LCA) and deoxycholic acid (DCA)) levels to promote hepatic bile acid sythesis via inhibiting LCA/DCA-FXR-FGF15 signalling pathway. Furthermore, XKY regulated amino acid metabolism including arginine biosynthesis, alanine, aspartate and glutamate metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, and tryptophan metabolism likely through increasing Bacilli, Lactobacillaceae and Lactobacillus, and decreasing Clostridia, Lachnospircaeae, Tannerellaceaeand Parabacteroides.
Conclusion: Taking together, our findings demonstrate that XKY is a promising “medicine food homology” formula for ameliorating glucolipid metabolism and reveal that the therapeutic effects of XKY may due to its downregulation on hepatic cholesterol biosynthesis, modulation the dysbiosis of gut microbiota and metabolites.