Non-Pathogenic Bacteria Modulate Colonic Epithelial Gene Expression in Germ-Free Mice

Background: We established a bacterial reconstitution model to investigate epithelial cell-luminal bacteria interaction. The aim of the study was to identify the known genes directly or indirectly modulated by non-pathologic bacterial flora in the colonic epithelia of germ-free mice. Methods: Germ-free mice were orally given a bacterial suspension prepared from specific pathogen-free counterparts (bacterial reconstitution). Colonic epithelial cells were isolated, then total and poly (A) RNA were extracted. We investigated differential gene expression in colonic epithelial cells among germ-free, bacteria-reconstituted, and specific pathogen-free mice by DNA microarray. Finally, differential expression was confirmed by Northern blot or quantitative RT-PCR. Results: Thirty genes were initially selected as differentially expressed genes in DNA microarray analysis. We confirmed that genes associated with growth (Reg III #, Reg III % , guanylate nucleotide binding protein 2), apoptosis (Bcl-associated dea...