Study on Bifidobacterium lactis-induced Th2 immune response in mice infected with Trichinella spiralis
Objective To investigate the effects of different doses of Bifidobacterium lactis on lymphocyte proliferation,thelper 2 cell(Th2)immunity and intestinal injury in mice infected with Trichinella spiralis.Methods A total of 48 mice infected with T.spiralis model were obtained by gavage with vibrant and energetic strains of the bacterium,randomly divided into infection group(0.02 mL/g PBS gavage),high dose-,medium dose-and low dose-B.lactis groups(1×106,1×105,and 1×104 CFU/L and 0.02 mL/g gavage,respectively)for 30 continuous day gavage.Thiazolyl blue(MTT)assay was used to detect the proliferation levels of T lymphocytes in mouse splenocytes of model mice on days 7th,14th,21st,and 28th.Flow cytometry was applied to detect the level of CD4+T cells and CD8+T cells in spleen and mesenteric lymph nodes.Hematoxylin-eosin(HE)staining was used to observe duodenum histopathology.Results When compared to infection group,stimulation indexes(SI)of splenic T lymphocytes were increased in high dose-and medium dose-groups(P＜0.05).When compared to infection group,high dose group of B.lactis showed an increase in CD4+T cell expression in the spleen on days 14th and 21st.On day 21st,there was a decrease in CD8+T cell expression in high-dose group of B.lactis and an increase in CD4+T cell expression in mouse mesenteric lymph nodes in high dose-and medium dose-groups(P＜0.05).When compared to infection group,high-dose administration of B.lactis resulted in reduced inflammatory cell infiltration and decreased shedding of intestinal villi on days 7th and 14th.Conclusion A certain concentration of B.lactis can enhance the immune response of mice against T.spiralis infection.Its mechanism may be related to inducing Th2 immune polarization and repairing mouse intestinal pathological damage.
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