72 Regulation by miR-195 of Actin-Related Protein-2 Translation Modulates Gut Epithelial Restitution After Wounding

G A A b st ra ct s may interact with mucosal immune cells to modulate the gut immune system or alternatively, the organism may act directly on the epithelial cells to strengthen the tight junction. Using a reductionist approach, we employed mice enteroid, a 3D structure grown from mouse intestinal crypts to investigate what components of the Lactobacillus rhamnosus GG (LGG) is responsible for improving mucosal permeability in the absence of immune modulators. Mouse enteroids were maintained in culture for 3 wks. We employed IFNgamma to induce epithelial barrier damage by causing disruption of tight junction (Plos One 2011;6:e22967). Mouse enteroids were incubated for 24 hr with IFNgamma (20 mg/ml) with or without cell-free LGG supernatant (5 μl/well), LGG extracted DNA (10 μg/ml) or LGG cell wall (4 mg/ ml). Incubation with IFNgamma caused a 80% and 67% downregulation of gene expression of occludin and ZO1 (P<0.05). These changes were accompanied by disruption of barrier function. Addition of LGG supernatant prevented these changes and normalized occludin and ZO1 to control levels. In contrast, additions of LGG DNA extracts or cell wall were without effects. These observations indicate that metabolites secreted by Lactobacillus rhamnosus GG but not the bacterial DNA or cell wall are responsible to prevent IFNgamma-induced epithelial barrier damage. This effect occurs independent of immune modulating effects of Lactobacillus rhamnosus GG and is mediated by upregulation of the scaffold protein ZO1 and transmembrane protein occludin.