Mechanism of Enterococcus faecalis MG 2108 against mouse colitis

Abstract:

[Objective] To screen probiotics with inhibitory effect on murine colitis induced by Citrobacter rodentium and to investigate the mechanism. [Methods] The tolerance of the four screened strains was tested with simulated gastrointestinal fluid, and their inhibitory ability against C. rodentium was examined in vitro. Finally, Enterococcus faecalis MG 2108 was screened out. A total of 72 male 7-week-old ICR mice were randomized into two groups after 7-day adaptive feeding:normal control group (MC, 24 mice, normal saline) and inflammation control group (IC, 48 mice, 1×10¹⁰ CFU/mL C. rodentium). After 7 days, 12 mice were respectively selected from the two groups and the inflammation was examined based on hematoxylin and eosin (HE) staining of colonic tissues and detection of inflammatory factors. The remaining 12 mice from the MC were renamed as NC to distinguish the normal control group before and after modeling. The mice of IC group were randomly divided into three groups:natural recovery group (IR, 12 mice, normal saline), ciprofloxacin group (CF, 12 mice, 4 mg/mL ciprofloxacin), and E. faecalis MG 2108 group (EF, 12 mice, 1×10⁸ CFU/mL E. faecalis MG 2108). After 18 days of gavage, all mice were anesthetized and dissected and blood was taken from the eyes. [Results] E. faecalisMG 2108 alleviated the injury of colon and liver induced by C. rodentium. E. faecalis MG 2108 promoted the repair of colon tissue via decreasing the expression of inflammatory cytokines and increasing the expression of tight junction protein.E. faecalisMG 2108 induced structural changes in gut microbiota, as the abundance of beneficial flora such as Enterorhabdus and Akkermansia increased in EF group, and the content of short-chain fatty acids (SCFAs) in EF group was higher than that in CF and IR groups (P<0.05). [Conclusion] E. faecalisMG 2108, an intestinal probiotic strain, shows better effect on the C. rodentium-induced colitis than ciprofloxacin, and the effect of IR group was significantly inferior to that of EF group.