Fufang Fanshiliu Decoction Revealed the Antidiabetic Effect through Modulating Inflammatory Response and Gut Microbiota Composition

BACKGROUND: Diabetes mellitus brings serious threats and financial burdens to human beings worldwide. Fufang Fanshiliu decoction (FFSLD), a traditional Chinese medicine formula showing great antidiabetic effects, has been used in clinics for many years. OBJECTIVE: This study aims to explore the underlying therapeutic mechanisms of FFSLD in Type II diabetes mellitus (T2DM). METHODS: Sprague–Dawley rats induced by high-fat diet feeding combined with streptozotocin injection were used to establish the T2DM model. All rats were randomly divided into 6 groups: control, model, metformin, high dosage, middle dosage, and low dosage of FFSLD. After 4 weeks of treatment, serum, intestinal mucosa, and fecal samples were collected for further analysis. ELISA was used to detect the diabetic-related serum indicators and proinflammation cytokines. Gene or protein expressions of mitogen-activated protein kinase (MAPK), interleukin 1 beta (IL-1β), transforming growth factor-beta (TGF-β), and tumor necrosis factor-alpha (TNF-α) in intestinal mucosa were analyzed by quantitative real-time polymerase chain reaction (RT-PCR) or western blot. 16s rRNA gene sequencing was used to detect the changes of gut microbiome in these groups. Intestinal gut microbiota (GM) composition was further analyzed according to the sequencing libraries. RESULTS: FFSLD effectively recovered the diabetic-related biochemical indexes by reducing fasting blood glucose (FBG), total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), insulin, and increasing high-density lipoprotein cholesterol (HDL-C). Furthermore, FFSLD significantly ameliorated the abnormal levels of proinflammation cytokines including IL-1β, IL-6, TNF-α, and TGF-β. In addition, the GM compositions of rats in control, model, and FFSLD treated groups were different. FFSLD significantly increased the relative abundance of Lactobacillus, Akkermansia, and Proteus, and reduced the relative abundance of Alistipes, Desulfovibrio, and Helicobacter. Moreover, these changed bacteria were closely related to the diabetic-related serum indicators and proinflammatory cytokines. CONCLUSION: These results suggest that FFSLD alleviates diabetic symptoms in T2DM rats through regulating GM composition and inhibiting inflammatory response, which clarify the therapeutic mechanism of FFSLD on T2DM and provide a theoretical basis for its further clinical application.