Effects Of Lactobacillus Rhamnosus On Differentiation And Development Of Dendritic Cells In BALB/c Mice Infected With Porcine Rotavirus

Poreine Rotavirus(PRV) was one of the major pathogens that cause viral diarrhea of piglets. Lactobacillus rhamnosus GG(LGG) could reduce distinctly morbidity of PRV,time of duration and diarrhea degree by improving defensive power of intestinal mucosa and clearance rate of the whole bacteria and viruses of the body and make a prominent contribution to steady state of intestines by regulating gastrointestinal mucosa immunity and then increasing antivirus ability of the organism. Dendritic cells(DCs) which was the foremost antigen presenting cells(APC) played an important role in the inherent immunity and adaptive immunity. The research on the differentiation and maturation status of the DCs and cytokines of the LGG immunization mice when were infected by PRV could contribute to know the mechanism of immune response of anti-PRV infection of LGG, thus provide theoretical guidance for the application of Lactobacillus in prevention and cure of the disease caused by PRV.108 BALB/c mice that were 3-4 weeks old were randomly divided into three groups including LGG+PRV group, PBS+PRV group and PBS control group in this experiment. Each mouse in LGG+PRV group took orally 100μL of LGG in concentration of 106 cfu every other day for 7 days before PRV challenge and 200μL on 8th day. The process in PBS+PRV group was the same as that of the LGG+PRV group exception of PBS instead of LGG. The process in PBS group was the same as that of the PBS+PRV group exception of PBS instead of PRV. Then body weight change status of the mice was observed and the detection of some indexes at 24 h, 48 h, 72 h, 96 h was carried out, respectively.(1) The detection of the sub-groups differentiation of CD11c+CD11b-CD8α+DC, CD11c+CD11b+CD8α-DC, CD11c+B220+CD8α+DC and CD11c+B220+CD8α-DC and that of the expression level of the co-stimulators MHC-Ⅱ, CD80, CD86, CD40 by flow cytometry(FCM) in MLN and spleen of the mice.(2) The detection of the mRNA expression level of TLR3, NF-kappaB, IL-6, IL-10, TNF-α, IL-12 and IFN-γ by Qrt-PCR in MLN and the small intestine of the mice.(3) The detection of the content change of IL-10 and IFN-γ by ELISA.The results showed as followed.(1) The differentiation of DCs sub-groups was different between LGG+PRV and PBS+PRV, of which LGG+PRV group was mainly differentiated towards CD11c+CD11b-CD8α+DC and CD11c+B220+CD8α+DC(P<0.05), however, PBS+PRV group was mainly differentiated towards CD11c+CD11b+CD8α-DC and CD11c+B220+CD8α-DC(P<0.05). This result indicated that the differentiation of CD8α+DCs was promoted and then the antigen was presented efficiently, and immunity response of initial T lymphocytes was activated and then adaptive immunity was activated after LGG immunization. Furthermore, the high expression level of MHC-Ⅱ, CD80, CD86 and CD40 of DCs, especially remarkable high expression level of MHC-Ⅱ+DCs(P<0.01) at 48 h indicated that DCs maturation was promoted in lymphoid organs after LGG immunization and the adaptive immunity was activated by induction of T cells immunological recognition and subsequent promotion of immunoreaction.(2) The results by Qrt-PCR test showed that mRNA expression level of TLR3, NF-κB, IL-12, IL-10, IL-6, TNF-α and IFN-γ increased, of which TLR3, NF-κB, IL-12, TNF-α and IFN-γ at 48-72 h showed significant expression(P<0.05) in LGG+PRV group. The mRNA expression levels was also showed increasing tendency in PBS+PRV group, of which IL-10 and IL-6 showed significantly increase(P<0.05), however, IFN-γ showed a decreasing tendency. The secretion of TLR3, NF-κB and other cytokines, especially inflammatory cytokines was promoted and then inherent immunoreaction was enhanced by activating TLR3 and NF-κB access, and leukocyte hybrid reaction and Th1/Th2 polarization occurred mediated by adaptive immunity so that the harmful damage to the organism could be avoided.(3) The expression level of IL-10, IFN-γ by ELISA test was further showed that immunity response was promoted and PRV infection was inhibited and relieved by mainly adjusting the secretion of Th1 and inflammatory cytokines to realize anti-PRV infection of LGG. The overall results showed that LGG could promote both inherent immunity response and adaptive immunity response to inhibit and relieve the PRV infection by promoting differentiation and maturation of DCs and secretion of TLR3, NF-κB and varieties of cytokines.