Characteristics Of Intestinal Flora In Obese Children And The Effects Of High Abundance Of Prevotella Copri On Metabolic Function In High-fat Diet Mice

Background and objectives: Child obesity has attracted massive attention from medical researchers and society.Obesity influences the growth and development of children’s organs and systems,which raises the incidence risks of chronic diseases,and imposes great health and economic burden on the families as well as the society.It is reported that the diversity and abundance of the intestinal bacterial flora play an important role in maintaining hosts’ healthy homeostasis.Recent studies have found that the dysregulation of intestinal bacterial flora is closely related to obesity,but the underlying mechanisms remain unknown.Prevotella copri is a common component found in intestinal bacterial flora,which is associated with glycolysis,dietary fiber metabolism,insulin resistance,etc.Our preliminary data revealed that the abundance of Prevotella copri was increased in children with obesity,indicating the potential association between Prevotella copri and child obesity.Based on this,we will investigate the characteristics of intestinal bacterial flora of obese children and reveal the effects of Prevotella copri on the metabolism of high-fat diet mice in this study.Hopefully,we will be able to provide novel directions for the mechanistic study of obese children and new theoretic evidence for the intervention and treatment of children obesity.Methods:(1)a total of 83 fecal samples of obese children and 107 samples of normal-weight children in Changsha were collected.We compared the differences of intestinal flora and abundance difference at the level of phylum,genus and OTU between obese children and normal weight children were compared using 16 S rRNA high-throughput sequencing technology and bioinformatics analysis.(2)After the high-fat diet mice transplanted with Prevotella copri,the body weight,glucose tolerance,and adipose tissue weight were measured,the morphological structure of adipose tissue and intestinal tissue were detected by HE staining,liver tissue fat content were detected using oil red O fat staining,the levels of lipid metabolism and inflammatory response factors were detected by ELISA experiment,short chain fatty acid and bile acid concentration levels detected by gas chromatography-mass spectrometry,16 S rRNA high-throughput sequencing was used to detect intestinal flora diversity and abundance,etc.,and designed to explore the effect of Prevotella copri on metabolic function of high-fat diet mice.Results:(1)16S rRNA high-throughput sequencing was used to detect the difference of intestinal flora between obese children and normal-weight children.The study found that the abundance of Prevotella copri was increased significantly in obese children(p<0.05).(2)The body weight of mice on high-fat diet increased significantly compared to normal diet mice(n=8,p<0.05),and the body weight of high-fat diet mice decreased slightly after administering of Prevotellacopri.The glucose tolerance of mice fed with high-fat diet decreased significantly(n=8,p<0.05),after administering of Prevotella copri of high-fat diet feed mice,and the glucose tolerance increased,but the effect was not significant;When compared the metabolic levels of lipid metabolic factors in the blood of mice,found the concentrations of cholesterol and triglyceride were the highest in the high-fat diet feeding group,and the concentrations decreased after administering of Prevotella copri(n=8,p<0.05);It was found that there was significant difference in low-density lipoprotein between high-fat diet group and high-fat diet + Prevotella copri group(n=8,p<0.05).HE staining of sebum and abdominal fat showed that Prevotella copri increased the size of fat vesicles.Oil red staining was used to detect the liver tissue of mouse model,and found that the high-fat diet + Prevotella copri group significantly reduced the fat content of mouse liver,the addition of Prevotella copri also significantly reduced the fat content of liver in normal diet mice group;Inflammatory factors of MCP-1 and IL-1β were detected and found the expression level decreased significantly in mice fed with high-fat diet(n=8,p<0.05),and expression levels increased significantly after administering Prevotella copri(n=8,p<0.05);It was found that only acetic acid had significant differences after testing the levels of short-chain fatty acid metabolism in different groups(n=6,p<0.05);The levels of bile acid metabolism were detected and found that there were some differences in cholic acid such as ursodeoxycholic acid,deoxycholic acid,orthocholic acid,glycodeoxycholic acid,chenodeoxycholic acid-3β-glucuronic acid,3β-cholic acid in groups(n=6,p<0.05);The results of microbial diversity analysis showed that there were significant differences among the different groups in the phylum level such as Bacteroides,Desulfobacterota,and Verrucomicrobia(n=6,p<0.05).Conclusions:(1)There was no significant difference in the diversity of intestinal flora between 86 obese children and 107 normal weight children used by alpha and beta diversity analysis.The abundance of Prevotella in the intestinal flora of obese children increased significantly.(2)The intake of Prevotella copri in high-fat diet mice had no significant effect on body weight and fat accumulation,but significantly increased glucose tolerance and insulin levels.(3)Prevotella copri significantly increased the levels of inflammatory cytokines MCP-1and IL-1β in serum of high-fat diet mice.(4)Prevotella copri can increase the relative abundance of Bacteroidetes in the intestinal flora of mice,and increase the metabolic concentration of ursus deoxycholic acid and 3β-cholic acid.