解淀粉芽胞杆菌C1 对金黄色葡萄球菌感染小鼠的免疫调节作用

Objective To explore the antibacterial activity and immunomodulatory mechanism of Bacillus amyloliquefaciens C-l in mice infected with Staphylococcus aureus in vivo. Methods A total of 48 female Kunming mice aged 6 to 8 weeks were randomly divided into the control group, infection model group, pre-vention group or treatment group. Staphylococcus aureus ATCC 25923 were inoculated through oral gavage to obtain the infection model. Prevention group and treatment group were inoculated through oral gavage with 2X109 CFU B. amyloliquefaciens C-l for 3 days before and after the infection; Control group was inoculated through oral gavage with saline. After the animals were sacrificed, intestinal tissues were sampled for HE staining and immunohistochemical analysis of histopathological changes. The cytotoxicity assay of intestinal epithelial cells HT-29 was used to detect the activity of Staphylococcus aureus toxin in intestinal Contents; the cytokines slgA, IFN-y, IL-2 and IL-6 in intestinal mucosa were detected using ELISA. The com-position of short-chain fatty acids in intestinal feces were detected with gas chromatography. Results The infection models were established successfully. The cytotoxicity assay of HT-29 and concentrations of slgA, IFN-y, IL-2 and IL-6 in the infection model group were higher than those in the control group (P=0. 039 2, P = 0. 042 3, P=0. 002 2, P=0. 001 0, P=0. 033 0). After Ol Intervention, the numbers of intestinal aci-nar hyperplasia and intestinal villus proliferating cells, intestinal Contents cytotoxicity, and the concentra-tions of slgA, IFN-y and IL-6 were all lower in C-l Intervention groups (prevention group and treatment group) than in the infection model group respectively; the Contents of IL-2 and SFCAs (propionic acid, bu-tyric acid, valeric acid) were statistically lower than in the infection model group, while those in the prevention group were lower than in treatment group, and the difference was statistically significant (P=0. 003 0, P = 0. 002 0, P<0. 000 1). Conclusion The probiotic B. amyloliquefaciens C-l can inhibit infection of Staphylococcusaureus by reducing intestinal colonization, limiting inflammatory responses and strengthening intestinal barrier, and the preventory effect is stronger than the treatment effect.