Intestinal microRNA Response to Citrobacter rodentium in the Presence and Absence of Bifidobacterium bifidum MIMBb75

The continuous crosstalk between gut microbiota and the host epithelium is essential for intestinal homeostasis. Presence of harmful or beneficial bacteria can impinge host gene expression and affect homeostasis. Yet, the molecular basis underlying host-bacterial crosstalk is unclear. The objectives of this project were to determine if pathogen infection impacts microRNA-mediated posttranscriptional regulation of gene expression in mouse intestine and if probiotic treatment improves pathogen-induced pathologies and microRNA alterations. It was found that Citrobacter rodentium infection alters murine colonic microRNA signature with implications in modulating host gene expression involved in the apoptosis pathway, contributing to the epithelial hyperplasia in response to Citrobacter rodentium pathogenicity. Probiotic Bifidobacterium bifidum MIMBb75 supplementation did not attenuate intestinal pathology nor normalize microRNA alterations. Overall, these findings indicate that host-bacterial crosstalk is potentially mediated by microRNA modulation, and this particular strain of Bifidobacterium bifidum did not confer apparent benefits in Citrobacter rodentium infection.M.Sc.2017-12-21 00:00:0