Bacillus subtilis inhibition of enterotoxic Escherichia coli-induced activation of MAPK signaling pathways in Caco-2 cells

Abstract

The aim of this study was to test the hypothesis that Bacillus subtilis antagonises enterotoxic Escherichia coli (ETEC) infection through mitogen-activated protein kinases (MAPK) signaling pathways. In vitro studies were performed in which ETEC-infected Caco-2 cultured human intestinal cells were first incubated with B. subtilis and then ETEC adhesion and MAPK activation were determined. Incubation with B. subtilis was found to reduce ETEC adhesion in Caco-2 cells by 58-72 % in the adhesive experiments (competition, exclusion, and displacement assays). ETEC was able to induce extracellular signal-regulated kinases 1 and 2 (ERK1/2) and p38 MAPK activation, but not c-Jun amino-terminal kinase (JNK) activation, in Caco-2 cells. ETEC-induced phosphorylation of ERK1/2, but not of p38, was inhibited significantly in ETEC-infected Caco-2 cells treated with B. subtilis. These findings suggest that B. subtilis is able to inhibit ETEC infection through blocking ETEC-induced ERK1/2 activation in Caco-2 cells. The data could provide a rationale for the clinical application of B. subtilis in enteric pathogenic infection. © 2012 Springer-Verlag and the University of Milan.