The Effect Of Compound Probiotics On The Intestinal Microecology Of Mice With E. Coli Inflammation

Studies have shown that high-fat diet induces obesity and causes intestinal microbiota disorders characterized by an increase in the number of Gram-negative bacteria,resulting in increased lipopolysaccharide content,intestinal mucosal permeability,and metabolic endotoxemia,followed by a systemic low-grade chronic inflammatory response.However,most of these studies established obesity mouse model with high-fat diet firstly,and then focused on the intestinal microbiota changes after different intervention treatments.Little work has been done on the use of gram negative bacteria to induce intestinal dysfunction and establishing obesity mouse model simultaneously,thus establishing the relationship between gram negative bacteria infection and high-fat diet induced obesity,which will provide more data illustrating the relationship between intestinal microbiota and obesity.Therefore,in this paper,the high-fat diet was used to establish the mouse obesity model while Escherichia coli was administered.The animals were divided randomly into the following six groups:group A was the control group,fed with base diet plus saline(0.2 mL/d)intragastrically;Group B was fed with high-fat diet plus saline(0.2 mL/d)intragastrically;group C was fed with base diet plus E.coli in saline(10~8 cfu/d)intragastrically;group D was fed with high fat diet plus E.coli in saline(10~8 cfu/d)intragastrically;group E was fed with base chow plus E.coli in saline(10~8 cfu/d)and compound probiotics(Lactobacillus plantarum-Bifidobacterium breve-Lactobacillus fermentum 10~8 cfu/d);group F was fed with high fat diet plus E.coli in saline(10~8 cfu/d)and compound probiotics(Lactobacillus plantarum-Bifidobacterium breve-Lactobacillus fermentum 10~8 cfu/d).After treatment for 3 wk,the group C to F stopped E.coli administration intragastrically.Group E and F were fed with probiotics for another 3 wk.The contents of immune factors and lipoproteins in peripheral blood were detected by ELISA,and liver tissue pathological sections were observed by HE staining.The fecal microbiota was analyzed using a 16S rDNA high-throughput sequencing platform at the end of the 3rd and 6th wk.And the feces short chain fatty acids(SCFAs)were measured by gas chromatography.Result:At the end of the 3 wk,the relative abundance ratio of Bacteroidetes to Firmicutes in A-F groups was 1.91,1.28,1.23,1.47,1.86 and 1.51,respectively.While at the end of the 6th wk,this ratio was 1.30,1.13,1.64,1.66,1.70 and 1.30,respectively,suggesting that the joint effects of high-fat diet with E.coli further increased intestinal microbiota disorder,with increased harmful bacteria.The compound probiotics reversed this tendancy.High fat diet caused increased fat content and infiltration of hepatic inflammatory cells in mice.The liver indexes were 4.69±0.81(group A),4.96±0.59(group B),4.54±0.52(Group C),4.49±0.39(group D),4.34±0.35(group E),and 4.95±0.16(group F)at the end of the 6th wk.The fat coefficients were 2.06±0.43(group A),3.67±0.94(group B),1.79±0.36(group C),4.04±0.95(group D),1.48±0.32(group E),and 2.24±0.37(group F).Group E and group C showed the lowest fat coefficients(p>0.05).E.Coli treatment decreased the feces SCFAs contents,which was reversed by probiotics treatment.Groups treated with compound probiotics reduced both LPS and IL-1?content,increased IL-10 level sin peripheral blood.In addition,probiotics inhibited esterase-CoA synthetase(ACS)activity,increased carnitine palmitoyltransferase(CPT)and glycerol kinase(PK)activities.The complex probiotics intervention improved the degeneration and inflammatory infiltration of mouse liver cells.This study showed that E.coli and high-fat diet could cause intestinal flora imbalance in mice,and increase the fat coefficient.High-fat diet reduced the proportion of Bacteroides to Firmicutes,and compound probiotics could increase the relative abundance of commensal bacteria effectively,and reduce the liver and fat index in mice.E.coli increased the concentration of inflammatory factors.The probiotics effectively reduced the body's inflammation while reducing the body fat content of mice and increasing the short-chain fatty acid content in feces.The probiotics also mproved liver cell inflammation and restored intestinal flora balance.