|Abstract:Abstract: Objective To investigate the effects of co-culture supernatant of Lactobacillus casei (LC) and Bacillus natto (BN) on intestinal micro-ecology, mucosal barrier function and immune function in mice with antibiotic-associated diarrhea (AAD). Methods 50 mice were selected, 40 of them were established AAD mice model. They were randomly divided into model group, LC group, BN group and co-culture group. The remaining 10 mice were control group. LC group, BN group and co-culture group were given LC, BN and co-culture supernatant respectively. Model group and control group were given the same amount of saline for 4 days. The general conditions of mice during the intervention were observed and the weight ratios of thymus and spleen of mice in each group were compared. Histopathological changes of proximal colon lesions were observed. The
red with the model group, the thymus, spleen weight ratio, Shannon, Chao index, Lactobacillus number, Bifidobacterium number, sIgA in intestinal mucosa, IL-2 and IL-2/IL-4 in intestinal tissue of the intervention groups were higher (P<0.05), and the co-culture group was higher than the LC group and the BN group (P<0.05). There was no significant difference between the LC group and the BN group (P>0.05). Compared with the model group, the number of Enterobacter, Enterococcus, serum DAO, bacterial ectopic rate and intestinal IL-4 in each intervention group were lower (P<0.05), and the co-culture group was lower than LC group and BN group (P<0.05). There was no significant difference between LC group and BN group (P>0.05). There were no significant differences in serum DAO, bacterial ectopic rate, sIgA, IL-2, IL-4 levels and IL-2/IL-4 levels between the co-culture group and the control group (P>0.05). Conclusion LC and BN co-culture supernatant can effectively regulate intestinal micro-ecology of AAD mice, improve intestinal mucosal barrier function, and improve intestinal and global immune function.
Shannon index and Chao index of cecum contents and the number of dominant bacteria in each group were compared. The serum diamine oxidase (DAO) level and bacterial ectopic rate in each group were detected were and compared. The levels of secretory immunoglobulin IgA (sIgA) in intestinal mucosa and interleukin (IL) -2 and IL-4 in intestinal tissue were detected. Results The mice in the model group showed poor mental state, decreased feeding intake and abnormal stool characteristics, which were aggravated with the prolongation of time. After intervention, the above-mentioned state of mice in each group was improved, and the recovery of co-culture group was the best. Histopathological results showed that the intestinal wall of the model group was severely damaged and villus was shedding. Cellulose-like exudation, necrosis of epithelial cells and infiltration of inflammatory cells could be seen in the model group. The pathological changes mentioned above were improved after intervention, and the co-culture group had the best effect. Compared with the control group, the thymus and spleen weight ratio, Shannon index, Chao index, Lactobacillus number, Bifidobacterium number, sIgA in intestinal mucosa, IL-2 and IL-2/IL-4 in intestinal tissue of the model group were lower, while the number of Enterobacteria, Enterococcus number, serum DAO, bacterial ectopic rate and IL-4 in intestinal tissue were higher (P<0.05). Compa