Effects Of Lactobacillus Rhamnosus On Balb/c Mice B Cells Development In Gut-associated Lymphoid Tissue

Lactic acid bacteria(LAB) is one of the most widely used type of probiotic which can be against pathogens, maintains barrier function. B cells is one of the important mucosal immune cells in the body, the important component of the cell in the gut associated lymphocytes tissue.After suckling mouse orally treated with lactobacillus,by examining the impact of the developmend and differentiation of B cells,helps to uncover the induced molecular mechanism of B cell development and differentiation by LAB as the normal intestinal microbiota, to provides scientific data for illustrating the development mechanism of LAB and the immune system.The specific contents and results are as follows:In this study, 50 1-week-old BALB/c mice were randomly divided into two groups, namely the PBS control group and Lactobacillus rhamnosus(LGG) group with 25 mice per group. Mice were orally administrated with LGG at the dose of 107cfu/ 10μL every another day for two weeks, mice treated with PBS were used as control. At 7d, 14 d, 21 d, 28 d and 35 d after the treatment, mice were detected following indicators:(1) Flow cytometry(FCM) detect developmental stages of the case which is B220+CD43+IgM-IgD-(pro-B),B220+CD43-IgM-IgD-(pre-B),B220+CD43-IgM+Ig D-(Immature-B)and B220+CD43-IgM+IgD+(Mature-B) in mouse spleen(SPL), mesenteric lymph nodes(MLN), pyle’s knot(PPs), bone marrow(BM) and intestinal lamina propria(IEL).(2) Flow cytometry(FCM) detect expression levels of CD40、CD80 and MHC-Ⅱ on B cells in mouse SPL, MLN and PPs.(3) The content change of SIgA content in intestinal lavage fluid and serum IgM, IgA and IgG were determined by ELISA.The results showed: Compared with the control group, in the first seven days LGG intervention, The number of Pro-B in BM is significantly reduced, as the intervention is stopped, the number of Pre-B and Immature-B increased significantly, then the number of Mature-B increased significantly;In the LGG intervention in the first seven days, the number of Pro-B cells in LPL was significantly increased, namely, to promote the Pro-B cell development, as the intervention is stopped, the number of Mature-B increased significantly, namely to promote the Pro-B to Mature-B cell development;After LGG intervention on day 14 in PPs the number of B220+ B increased significantly, no significant differences compared to the Pro-B cell number with the control group, Pre-B on the rise, a significant increase in 14 and 21 days, 28 days significantly reduced, number of immature-B increased significantly in 21 days, 28 days significantly reduced,the number of Mature-B significantly decreased in the first 14 days. Meanwhile the first 7 days in SPL and MLN the number of B220+ B lymphocytes increased significantly, after LGG intervention the number of Mature-B cells significantly increase in the first 7 days and 35 days in the SPL,the number of Mature-B cells in the MLN were significantly reduced. In summary explanation, mice were orally LGG to promote Pro-B cell development, promotion of B lymphocyte maturation; at the same time be able to regulate the adaptive immune response of B cells are involved, so that defense and resistance of pathogenic microorganisms infections.The expressions of CD40, CD80 and MHC-Ⅱon B cell were also determined and the results showed that the treatment with LGG inhibited the expression of CD40, CD80 and MHC-Ⅱon B cell surface at the beginning. Along with colonization in the intestine,LGG could increase the expression of CD40, CD80 and MHC-Ⅱon B cell surface. LGG began to inhibit B cell activation and antigen-presenting ability to create good conditions for colonization of LGG at the beginning, whereas the stability of LGG defaults in the intestine can promote B cell activation and antigen presenting capability to increase B cell activation and delivery of antigen-presenting ability. ELISA test results further validated the results. In the LGG intervention, the secretion of the intestinal mucosa SIgA increased significantly; LGG early intervention, compared with the Control group, the reduction in serum IgA secretion LGG group, and IgM and Ig G secretion increased; With the intervention is stopped, LGG group, serum IgA and IgM secretion increased, while reducing the amount of IgG secretion. It showed that LGG intervention regulate B cell immunoglobulin secretion, thus defense and resistance of pathogenic microorganisms infections.