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

Table 2 Summary of the magnitude of effect of combinations of cytokines and hydrogen peroxide on transepithelial electrical resistance, mannitol leak, lactulose leak and polyethylene glycol leak

	Transepithelial electrical resistance decrease	Mannitol leak increase	Lactulose leak increase	Polyethylene glycol leak increase
TNF	++	1	0	ND
TNF/IFN	+	1	0	ND
TNF/IFN/IL1β	+	++	0	0
TNF/IFN/IL1β + hydrogen peroxide	++++	++++	++++	++++

CACO-2 cell layers having been exposed to the above combinations of cytokines and hydrogen peroxide were evaluated for type (salts, mannitol, lactulose, PEG) and magnitude of leak produced. All treatments increased leakage of salts as seen by a decrease in TER, but large molecule leak was seen only in the presence of peroxide alone or both cytokines and hydrogen peroxide, never in the presence of cytokines alone.

¹Indicates that the observed effect did not routinely achieve statistical significance;

⁰Indicates that an effect was measured but no significant change was observed. ND: Not determined; IFN-γ: Interferon-γ; IL1β: Interleukin-1β; TNF-α: Tumor necrosis factor-α; PEG: Polyethylene glycol.