The Effects Of Lactobacillus Delbrueckii On Intestinal Dendritic Cells And Related Cytokines Of Suckling Piglets

This paper explores the effects of the external Lactobacillus delbrueckii on intestinal dendritic cells and related cytokines of suckling piglets,then to provide theoretical and experimental datas of Lactobacillus widely applied in livestock production.Selecting healthy newborn piglets in6litters which have similar parity, same period and mean litter size about8-11.Adjusted number of piglets to8per litter with half males and half females. Divided every litter into the control group and the expriment group randomly(each group has two males and twe females,ear tag to distinguish every piglet). At birth before eating breast milk,4d,8d,15d each suckling piglet of the experimental group is garaged with1,2,3,4ml live L. delbrueckii(5×108CFU/ml) per time,while the control group is garaged with1,2,3,4ml saline normal per time. Trial period is21d from birth to weaning. Record the birth weight,weaning weight, the diarrhea and death cases of piglets carefully during the test. On the21th day,a young boar from each group in each litter is killed randomly, collecting their intestinal segment tissues and scrap the ileum mucosa.By used of immuneohistochemical,quantitative real-time PCR and ELISA, to test analysis on the number of DC, the mRNA expressions of antigen recognition receptors TLRs and the related cytokines,as well as Th1/Th2cytokines production in mucosa.The results are as follows:(1) The experiment piglets compared with the control piglets, there were no significant differences(P>0.05)of the final weight and daily gain;In the first7d, there were no significant differences(P>0.05)of the diarrhea rate;the experimental piglets of diarrhea rate were reduced by26.7%in0to14d(P<0.05),and throughout the trial period(21days of age), there were no significant differences(P>0.05)of the diarrhea rate,but there had a downward tend;(2) The results of immunohistochemistry indicated that DCs were present in the intestinal lamina propria of piglets,and the cytoplasm and cell membrane were both stained with brown.Image-Pro Plus6.0(IPP6.0) analysis showed that the L.delbrueckii could improve the number of DC in the small intestinal musocal lamina propria of piglets and had significant differences (P<0.05).(3) Compared with the control group,the expressions of DC recognition receptors TLR2and TLR4were elevated in intestinal mucosa (P>0.05); IL-2mRNA production was increased in intestinal mucosa of the expriment group piglets(P<0.01); the expressions of both IL-6and IL-10had no significant difference(P>0.05),but the expriment piglets had a upward trend.Productions of IL-4,IL-12and IFN-y from intestinal mucosa of two groups had no significant difference(P>0.05).(4) From the protein level,the experimental group both IL-2and IL-12contents were lower than the control group,but had no significant differences (P>0.05),while IFN-y and IL-6protein level had a upward trend(P>0.05).L.delbrueckii can prevent piglets diarrhoea effectively in the early stages of breast feeding; External L.delbrueckii can increase the number of DCs in Jejunal segment and ileum of suckling piglets, can promote TLR2,TLR4mRNA production in the intestinal mocosa,and promote related cytokines especially IL-2secreting. And the regulation of Lactobacillus on the production of cytokines is likely to maintain an important mechanism of mucosal immune function. In normal physiological conditions, L.delbrueckii can reduce Thl immune response in intestine mucosa of piglets,and might plays a promoting role in T cell to2-type cell differentiation.