Modulation of Escherichia coli O157:H7 mediated production of proinflammatory mediators by two species of Lactobacilli in two conditionally immortal colon epithelial cell lines

We hypothesized that probiotic bacteria, Lactobacillus casei (LC) and Lactobacillus reuteri (LR) would decrease production of proinflammatory mediators (e.g. nitric oxide [NO], chemotactic cytokines [MIP-2, TNF-a by ELISA]) in response to exposure to bacterial pathogen E.coli O157:H7 (EC). Two non-tumorigenic murine colon epithelial cell lines (i.e. Young Adult Mouse Colon [YAMC, Apc+/+]; Immortomouse/Min Colon Epithelial [IMCE], ApcMin/+ cells) were used to assess the production of NO and cytokines when treated with bacteria, spent medium or both.;EC caused a concentration-dependent increase in NO and MIP-2 production compared to control (p < 0.001). LC and LR co-treatment with EC caused a decrease (p < 0.001) in NO production compared to EC treatment in both cell types. EC/LC co-treatment also attenuated (p < 0.001) MIP-2 production compared to EC treatment.;The use of inhibitors of NF-kB, p38 MAPK, and JNK individually and p38 MAPK/JNK in combination accomplished partial inhibition (p < 0.001) of EC induced NO and MIP-2 production. The use of hemoglobin indicated an NO-independent mechanism was activated in the presence of EC in potentiation of MIP-2 production. These results suggest that probiotic bacteria influence proinflammatory mediator production in colon-epithelial cells in a genus- and species- specific fashion, affecting both quantity of immune cells and type attracted under inflammatory conditions.