[Lactobacillus rhamnosus GG improves symptoms and its mechnism in mice with ovalbumin-induced food allergy].

Objective To investigate the effect of Lactobacillus rhamnosus GG (LGG) on peripheral blood IL-4/IFN-γ in mice with ovalbumin-induced food allergy. Methods The mice with food allergy were divided into 3 groups (n=10 in each group): food allergy model group, low-dose LGG group (1×10 CFU/mL, 200 μL/d) and high-dose LGG group (1×10 CFU/mL, 200 μL/d). The healthy mice (n=10) served as a control group. Mice in the LGG groups were given LGG for consecutive 22 days after modeling. The control mice and the food allergy model mice were given normal saline instead of LGG. At day 23, the allergic score, body mass, thymus index, spleen index were recorded and calculated; the expressions of IgE, IL-4 and IFN-γ in peripheral blood were detected by ELISA; the pathological changes of small intestines were observed by HE staining and fecal flora were examined by bacterial culture. Results The thymus and spleen indexes had no significant differences within the 4 groups. Compared with the control group, IL-4, allergic score, E.coli and bacteroides increased, and IFN-γ, IFN-γ/IL-4, IgE, body mass, Bifidobacterium and Lactobacillus decreased in the mice with food allergy. Compared with the mice with food allergy, IL-4, allergic score, E.coli and Bacteroides decreased significantly, and IFN-γ, IFN-γ/IL-4, IgE, body mass, Bifidobacterium and Lactobacillus significantly increased in the LGG groups in a dose-dependent manner. In the food allergy model group, some edematous and necrotic epithelial cells were found in intestinal mucosa. Compared with the food allergy model group, the intestinal mucosa was integrated and the intestinal cells appeared ordered in the LGG groups. Conclusion LGG can remarkably improve the symptoms of ovalbumin-induced food allergy probably by decreasing IL-4/IFN-γ ratio.