Sieving characteristics of cytokine- and peroxide-induced epithelial barrier leak: Inhibition by berberine.

Aim: To study whether the inflammatory bowel disease (IBD) colon which exhibits varying severity and cytokine levels across its mucosa create varying types of transepithelial leak.

Methods: We examined the effects of tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-1-β (IL1β) and hydrogen peroxide (H2O2) - singly and in combinations - on barrier function of CACO-2 cell layers. Our focus was on the type (not simply the magnitude) of transepithelial leak generated by these agents as measured by transepithelial electrical resistance (TER) and transepithelial flux of (14)C-D-mannitol, (3)H-Lactulose and (14)C-Polyethylene glycol as radiolabeled probe molecules.