Polysaccharide From Salviae Miltiorrhizae Radix Et Rhizoma Attenuates The Progress Of Obesity-induced NAFLD Through Modulating Intestinal Microbiota-related Gut-liver Axis

Object: In recent years,with the prevalence of obesity and metabolic syndrome,the prevalence of Nonalcoholic fatty liver disease(NAFLD)is also increasing worldwide,and NAFLD has become the largest chronic liver disease in China.Salvia miltiorrhizae Radix et Rhizoma is a plant of the Labiatae family and its dried tuberous root is the main medicinal part.SMRR polysaccharide,an active ingredient of Salvia miltiorrhiza,has been studied for its complex and diverse biological activities and functions,which can be used for the treatment of cardiovascular diseases,liver injures,etc.However,the underlying mechanisms in liver injures are not well defined.In this study,we aim to evaluate whether polysaccharides from SMRR ameliorated obesity-induced NAFLD and to investigate the potential function of SMRR polysaccharides in the gut-liver axis and its correlation with the gut microbiota,providing evidence for further development and utilization of SMRR.Methods: In this study,the crude polysaccharide was isolated by hot water extraction and ethanol precipitation,and then purified by DEAE anion exchange chromatography and gel filtration to obtain the SMRR polysaccharide.4-week-old C57BL/6 mice were used as subjects,and Normal Diet mice were used as control.The NAFLD model of mice was established by feeding High Fat Diet(HFD)for 8 weeks.Liver,intestinal,serum and faecal were collected after the mice were executed.The level of body weight,food intake,Serum biochemistry and histology were used to assess of the success of modelling of high-fat diet-induced NAFLD,anti-obesity and liver protection.Liver fat accumulation and liver injury were observed by HE staining,Masson staining and S Picro Sirius Red staining.The level of serum AST and ALT was assessed to evaluate the degree of liver injury.Subsequently,q RT-PCR were used to detect the expression changes of inflammatory factors and fibrosis related genes from the perspective of m RNA level.16 S r RNA was used to assess the composition of the intestinal microbiota.The above methods were used to investigate the alleviation of the high-fat-diet-induced NAFLD process by SMRR polysaccharides.Results: The extraction rate of crude polysaccharide of Salvia miltiorrhiza was 21.5%and the yield of acidic polysaccharide was 42.4%.The model of high-fat-diet-induced NAFLD in mice was successfully constructed;SMRR polysaccharide attenuated high-fat-diet-induced obesity;SMRR polysaccharide alleviated the progression of NAFLD;SMRR polysaccharide improved the intestinal structure and permeability defects which were caused by high-fat-diet;SMRR polysaccharide improved liver and intestinal inflammation in mouse caused by high-fat-diet;SMRR polysaccharide ameliorated the changes in the composition and structure of intestinal microbiota induced by high-fat diet.Conclusions: These results suggested that HFD-induced NAFLD model was successfully constructed in mice,we found that consumption of the SMRR polysaccharide could remarkably reverse obesity and its related progress of NAFLD,including reduction of hepatocellular steatosis,hepatic fibrosis and inflammation.At the same time,SMRR polysaccharide also had biological activities that improved intestinal permeability,structure and function,and regulated intestinal microbiota homeostasis.Finally we also revealed the potential mechanism behind these was that the SMRR polysaccharide could regulate the gut–liver axis through modulating the homeostasis of gut microbiota and thereby improving intestinal function.