SECRETED BIOACTIVE FACTORS FROM BIFIDOBACTERIUM INFANTIS MODULATE EPITHELIAL CELL BARRIER FUNCTION

Search CDDW 2006 Abstracts

SECRETED BIOACTIVE FACTORS FROM BIFIDOBACTERIUM INFANTIS MODULATE EPITHELIAL CELL BARRIER FUNCTION

J Ewaschuk, L Meddings, J Walker, K Madsen
Department of Medicine, University of Alberta, Edmonton, Alberta

The ability of the intestinal tract to act as a barrier between the external environment and the closely regulated internal milieu is essential for human health. Failure or even mild perturbation of intestinal barrier function has been demonstrated to have either a causal or contributing role to the pathogenesis of numerous diseases, including IBD, type I diabetes, and alcoholic liver disease. Contributing to the barrier function of the intestine are several interrelated systems, including epithelial cells, and innate and adaptive immune responses. We have previously reported that certain strains of Bifidobacteria release bioactive factors that can promote intestinal epithelial barrier function in vitro. However, it is not known if these peptide bioactive factors would retain biological activity when given orally.
OBJECTIVE: The objective of this study was to characterize the effects of Bifidobacteria-produced bioactive factors on epithelial tight junctions, and to determine if these bioactive factors decrease intestinal permeability when administered orally.
METHODS: Bifidobacterium infantis was incubated overnight in RPMI-1640 media. The media was centrifuged and filtered to remove live bacteria; a sample was cultured to ensure removal. This conditioned media (CM) was applied to T84 human epithelial cells in a dose-and time-dependent manner. Tight junction proteins and mitogen-activated protein kinases (p38 and ERK) were measured by Western blot. To investigate the in vivo effects of CM, adult 129/SvEv mice were treated with pentoprazole (1 mg/kg/2´ daily) for two days, followed by oral administration of CM (30 µl/2´ day). Twenty-four hours later, mice were sacrificed and colons removed for measurement of epithelial permeability in Ussing chambers by measuring ³H-mannitol fluxes and tissue conductivity.
RESULTS: CM treatment of T84 cells resulted in a time-dependent decrease in phospho-p38 in conjunction with an increase in phospho-ERK. An increase in claudin-1 expression occurred within 2 h of CM exposure. This correlated with enhanced epithelial resistance and decreased mannitol fluxes. Mice treated with CM demonstrated decreased proximal colonic permeability and reduced tissue conductivity.
CONCLUSION: B infantis secretes novel bioactive peptides that modulate epithelial cell barrier function through alterations in claudin expression. Furthermore, these bioactive factors remain active following passage through the stomach and small intestine, suggesting the potential for these factors to be used as treatment for gastrointestinal conditions involving failure of barrier function.

PREVIOUS NEXT