Effect And Mechanism Of Preventing And Treating Colitis In Mice By Lactobacillus

Inflammatory bowel disease(IBD),including Ulcerative colitis and Crohn’s disease,may further develop into colorectal cancer.The occurrence and development of IBD are closely related to genes,environment,and the patient’s immune status.Current therapeutic drugs such as salicylic acid preparations and steroid hormones have side effects and are not suitable for long-term use.Therefore,the development of natural biological agents has important value.Probiotics(Lactobacillus,Bifidobacterium,etc.)have been reported in the literature to improve IBD symptoms.They play a preventive and therapeutic role by regulating the balance of Gut microbiota,maintaining the stability of intestinal barrier and improving body immunity.Therefore,based on the acquisition of mouse derived Lactobacillus,a systematic study on its prevention and treatment of IBD was carried out.The main research content and results are as follows.Lactobacillus reuteri GLRE01 and Lactobacillus johnsonii GLJO02 were isolated by traditional microbial isolation method,and their probiotic properties were studied.The results showed that under treatment with p H2.5 and 3.5,0.1%,and0.15%bile salt concentrations for 6 hours,the biomass of both strains of bacteria could maintain above 10~5cfu/m L from the initial 10~7cfu/m L;After simulating the gastrointestinal fluid environment for 7 hours,the biomass of both probiotics can be maintained at around 10~9cfu/m L from the initial 10~9cfu/m L;The results of the adhesion experiment showed that the adhesion rates of GLRE01 and GLJO02 were7.15%and 32.2%,respectively.Both strains of Lactobacillus have good probiotics and stress resistance,which can be further used for research on the prevention and treatment of colitis in mice.Using DSS to construct a mouse model of colitis,the effects of Lactobacillus reuteri GLRE01 and Lactobacillus johnsonii GLJO02 on alleviating colitis were studied.The mice were randomly divided into Control+PBS group,DSS+PBS group,DSS+GLRE01 group,and DSS+GLJO02 group.The results showed that compared with the DSS group,GLRE01 and GLJO02 both alleviated DSS induced colitis in mice,maintained body weight(P<0.05),decreased DAI score(P<0.01),increased colon length(P<0.01),decreased serum LPS levels(P=0.11),regulated cytokine expression(P<0.05),and increased cecal SCFAs levels(P<0.01).16S rRNA gene high-throughput sequencing was found in Gut microbiota of mice.There was no significant difference in Shanon index among the four groups(P>0.05);βThe diversity of PCA and PLS-DA analysis showed that the Gut microbiota of probiotic group was significantly different from that of DSS group;Species composition analysis and LEf Se analysis found that Lactobacillus royi GLRE01 and Lactobacillus yoelii GLJO02 could improve the relative abundance of Bacillota,Clostridiales,Clostridium and Bacteroides caused by DSS,and both GLRE01 and GLJO02 could reduce the relative abundance of Pseudomonadota Relative abundance of Enterobacterales and Enterococcus.Use fluorescence real-time quantitative technology to detect macrophage inflammatory factors and study the effect of Short-chain fatty acid on LPS+IFN-γThe effect of inducing M1 type polarization in THP-1 cells.The results showed that Short-chain fatty acid could significantly down regulate THP-1 inflammatory factor(Tnf)in M1 polarized Monocyte-α、Il-1βAnd Inos)expression level(P<0.05),the expression of M1 macrophage marker Cd86(P<0.01),and the expression of G protein-coupled receptor Gpr41 and Gpr43(P<0.01);Upregulate the expression of M2 type macrophage markers(Cd206,Arg I,and Ccl18).To sum up,Lactobacillus reuteri GLRE01 and Lactobacillus johnsonii GLJO02are probiotics with excellent performance.They can regulate Macrophage polarization and improve the structure of Gut microbiota in mice.At the same time,they can promote the production of Short-chain fatty acid in the intestine.Short-chain fatty acid can regulate Macrophage polarization and then inhibit inflammation by competing with LPS for GPR41/GPR43 receptor sites.The research results of this article will provide data support for the development and application of Lactobacillus johnsonii and Lactobacillus reuteri.