Effects Of Lactobacillus Rhamnosus On Abundance Of Mouse Gut Microbiota And The Tlymphocytes Subsets

An animal gut is an open ecological system that is colonized by large numbers and variety of microorganisms.The microbiome is primarily bacterial, but also contains fungi, yeast, viruses,and archaea. The microbiota has coevolved relationship with the host immune system and plays an important role in maintaining intestinal homeostasis.It is clear that gut microbiota actively modulate the immune system to maintain a mutually beneficial relation, but the mechanisms that maintain homeostasis are not fully understood.Lactic acid bacteria is the main genus of intestinal microbiota, is probiotics animal body, they can improve the intestinal microbiota, help maintain some of the biological immune system function.Explore the impact of lactic acid bacteria on intestinal microflora abundance and diversity, and the effects of lactic acid bacteria on intestinal immune response, which provides a theoretical basis for the study of lactic acid bacteria to improve the intestinal microbiota, as well as to uncover the mechanism of lactic acid bacteria on the role of immune response. The contents and results are as follows:In this study, Lactobacillus rhamnosus GG(LGG) ATCC 53103 intervention BALB/c mice;The 45 6-week-old female BALB/c mice were randomly divided into three groups with 15 mice per group. Control group(Control): Mice were orally administrated with PBS at the dose of200μL every another day for 7 times; Low dose group(LLGG): Mice were orally administrated with LGG at the dose from 103 to 109CFU/day,every another day for 7 times, the total dose of1.11 × 109CFU; High-dose group(HLGG): Mice were orally administrated with LGG at the dose of 109CFU/day, every another day for 7 times,the total dose of 7 × 109 CFU.After the treatment, mice were detected following indicators: The Illmnina high-throughput sequencing technology analyze the changes of gut microbiota abundance and diversity in mouse fecal;Flow cytometry detect the changes of T, B lymphocytes in mouse spleen(SPL), mesenteric lymph nodes(MLN), peyer patchs(PPs) and intestinal lamina propria(LPL); The content change of IFN-γ and IL-4 in serum were determined by ELISA.The results showed: After LGG intervention BALB/c mice, according to sequencing results obtained Observed OTU, Chao1, ACE, Simpson and Shannon index, LLGG and HLGG could improve Observed OTU, Chao1, ACE, and Shannon index, while reducing the Simpson index,and significantly improve Chao1 and ACE index by LLGG. It shows that LGG can promote intestinal microbiota abundance and diversity, and low doses of LGG can be better to promote intestinal flora abundance and diversity; While both groups could increase the numbe ofintestinal Firmicutes, Bacteroides and Actinomycetes, while reducing the number of Proteobacteria. LLGG can improve Blautia, Bacteroides, Alistipes and Lachnospiraceae NK4A136, while reducing Desulfovibrio, Akkermansia and Odoribacter; HLGG could improve Akkermansia, Alistipes, Bacteroidales S24-7_group_norank and Lactobacillus, while reducing Desulfovibrio, Blautia and Odoribacter, it shows that LGG can increase dominant intestinal flora status; HLGG and LL GG both can affect the CD3+T lymphocytes in SPL, MLN, PPs and LPL; High dose group can improve the percentage of the CD3+T, CD3+CD4+T and lymphocytes CD3+CD8+T; While the low-dose group increased the percentage of the CD3+T lymphocyte in LPL and SPL, increased the percentage of CD3+CD4+T lymphocyte, reduced the percentage of CD3+ and CD3+CD8+T lymphocytes in MLN and PPs, but little effect on the SPL; These instructions that LGG intervention with mouse, can significantly affect the proliferation and distribution of CD3+T, CD3+CD4+T and CD3+CD8+T lymphocytes in mouse SPL, MLN, PPs and LP. HLGG have a significant effect on the percentage of T cells.Meanwhile, LGG can effectively promote cytokines corresponding(IFN-γ, IL-4) by the CD4+T cells secreting in mouse SPL and MLN, LLGG and HLGG can enhance Th1-type cytokines(IFN-γ) and Th2cytokines(IL-4) expression levels, So that the proportion of Th1 and Th2 T cells in mouse compared with control group is in high equilibrium statethe. In addition, IL-4/IFN-γ ratio is greater than 1, indicating that LGG tends Th2 mediated immune responses; Meanwhile, HLGG compared LLGG, significantly increased Th1-type cytokines(IFN-γ) and Th2 cytokines(IL-4)expression levels. It shows that HLGG more likely mediated immune response by Th2 type.And the ELISA results show: LGG can dose-dependent increase the content of IFN-γ and IL-4 in the serum, and IL-4/IFN-γ ratio is greater than 1,and further confirms the above conclusion. LLGG and HLGG increased the expressionin of Th17 cytokine(IL-17) in SPL and MIN, indicating that LGG can promote Th17 differentiation; LLGG increased in the number of Tregs cells in SPL,while down the number of Tregs cells in MLN and PPs; HLGG could increase the number of Tregs cells in PPs, the lower the number of Tregs cells in MLN,there was no significant difference in SPL regulation. In summary, LGG intervention mouse improving the balance of intestinal flora of the host, thereby enhancing the intestinal immune system.