Amelioration of the Effects ofCitrobacter rodentiumInfection in Mice by Pretreatment with Probiotics

Abstract

Pretreatment with probiotics attenuates the effects of C. rodentium infection in mice. Understanding the mechanism of these beneficial effects will aid in determining the efficacy of probiotics in preventing infection with related attaching-effacing enteric pathogens in humans.

Lactobacillus rhamnosus Strain GG Prevents Enterohemorrhagic Escherichia coli O157:H7-Induced Changes in Epithelial Barrier Function

“…We have previously shown that in vivo use of a probiotic mixture containing L. rhamnosus R0011 and Lactobacillus helveticus R0052 in mice is beneficial in ameliorating intestinal injury in response to C. rodentium (19,20), gastric injury in response to Helicobacter pylori infection (21), and stress-induced barrier dysfunction in epithelial ultrastructure in the colon of stressed rats (48). The response to a nonspecific injury, such as stress, leads to defective mucosal barrier function, enhanced luminal bacterial adherence, and alterations in cellular morphology (40,41 (46) demonstrated that secreted proteins of L. rhamnosus GG prevent tumor necrosis factor alpha-induced apoptosis in human and mouse epithelial cells.…”

“…Effects of viable probiotics and their products on pathogen viability. The effects of probiotics on the viability of the pathogen were assessed using coincubation methods, as previously described (20). Briefly, L. rhamnosus GG (10 8 CFU/ml) was coincubated at a ratio of 1:1 (vol/vol) with E. coli O157:H7 (10 7 CFU/ml) in Penassay broth (10 ml) for 3 and 18 h at 37°C.…”

“…Culture supernatants were prepared as previously described (20). Briefly, supernatants resulting from 4 h of growth of L. rhamnosus GG in MRS broth were centrifuged at 1,600 ϫ g for 5 min and filtered twice through a 0.2-m filter (Millipore).…”

“…To assess epithelial cell monolayer structures, polarized epithelial cells were prepared as previously described, with minor modifications (20). Briefly, MDCK-I cells were grown on 60-mm plates at 37°C in the presence of 5% CO 2 to confluence.…”

“…Probiotics exert their beneficial effects by a variety of complementary mechanisms, including an ability to modulate host innate immune responses, such as secretion of mucins from goblet cells, adaptive immune responses, protection from the damaging effects of aspirin, and competitive exclusion of pathogens (36). In addition, we have previously shown that probiotics have the ability to decrease Citrobacter rodentium-induced mucosal inflammation and disruption of paracellular junctions (20).…”