The Mechanism Of Lactobacillus Acidophilus La-5 In Prevening NAFLD Induced By High-fat Diet In Rats

AimsA high-fat diet(HFD)was used to induce non-alcoholic fatty liver disease(NAFLD)model in Sprague-Dawley(SD)rats to stimulate NAFLD in children.Two different doses of Lactobacillus acidophilus La-5 were used into prevention of NAFLD to observe the better effect of La-5.To explore the variant metabolism of bile acids(BA)and gut microbiota(GM)in process of NAFLD induced by HFD and the prevention by La-5.To illuminate the variation in serum BAs and fatty acids(FA)in NAFLD children and adolescents.The aim of this study was to provide a theoretical basis and a strategy for preventing NAFLD in children through maintaining the stability of GM and balance of BAs.MethodsIn the first part,the NAFLD rat model stimulating NAFLD in children was induced by HFD containing 40%fat.The second one is the part of probiotics prevention.After the establishment of the NAFLD model,24 SD rats of 3-week-old were randomly divided into4 groups:the normal control group(NC),the high-fat control group(HC),the probiotics Lactobacillus acidophilus La-5 low dose group(PL),the probiotics Lactobacillus acidophilus La-5 high dose group(PH).NC group was fed with normal diet,while the other three groups were fed with high-fat diet.PL group(3×10~8CFU/day)and PH group(3×10~9CFU/day)were treated with Lactobacillus acidophilus La-5 gavage,and NC group and HC group were given an equal volume of saline.The dynamic body weight and food intake were recorded.After 16 weeks,the serum biochemical indexes,fat contents in liver and viscera were measured.16S r RNA gene sequencing technology was used to analyze the fecal flora composition of rats in four groups.And ultra high performance liquid chromatography-tandem mass spectrometry was used to detect bile acids in liver,serum and feces.The third part was clinical research.77 children and adolescents of 4-to 17-year-old were collected.They were divided into three groups according to liver ultrasound results:the normal control group(n=36),mild fatty liver group(n=18),moderate/severe fatty liver group(n=23).The clinical informations were collected.The physical exmaninations were measured and the serum biochemical analysis was detected.Ultra high performance liquid chromatography-tandem mass spectrometry was used to detect serum bile acids,and gas chromatography was used for detection of serum fatty acids.ResultsIn the animal research,the hepatic steatosis associated with the intestinal dysbacteriosis(decreased Firmicutes and increased Bacteroidetes)and decreased secondary BAs(SBA)in liver,serum and feces in HC rats.Prevented with high dose of Lactobacillus acidophilus La-5,the levels of weight,serum insulin,total cholesterol,visceral fat were lower in rats of PH group than those of HC group.In PH rats,the hepatic steatosis was unconspicuous associated with the normalization of GM(increased Firmicutes and decreased Bacteroidetes)and BA profiles(increased SBAs).In the clinical research,it was characterized by decreased levels of several compositions of SBAs in all the NAFLD children and adolescents,while by increased levels of composition in primary BAs(PBAs)in moderate/severe NAFLD ones as compared to those in control,respectively.In serum fatty acid(FA)composition analyzation,it was characterized by increasd level of n-7 monounsaturated fatty acid(MUFA)in NAFLD children and adolescents,compared to the control.ConclusionsIn this study,it was shown HFD could result in the gut dysbacteriosis,imbalanced BA metabolism and hepatic steatosis.The imbalance of GM and BA metabolism were involved in the pathogenesis and progress of NAFLD.Addition of 3×10~9CFU/day Lactobacillus acidophilus La-5 could stabilize GM and balance BA metabolism in vivo so as to be effective on preventing NAFLD induced by HFD in rats.It was also found the serum BA profiles as well as FA compositions altered in NAFLD children and adolescents.The variations of serum BA and FA profile were characterized in different stage of NAFLD in children.In brief,the BAs variation in NAFLD children and adolescents were found similar with those in NAFLD rats model to some extent,which might be of great significance from the new sight in prevention of NAFLD in children by means of probiotics.