Objective        To investigate the protective effect of berberine (BBR) on intestinal epithelial barrier function during inflammation and the underlying mechanism.       Methods        The intestinal epithelial cell line Caco-2 monolayers were divided into a control group

a BBR group

a TNF-α+IFN-γ group and a TNF-α+IFN-γ+BBR group. Both of TNF-α and IFN-γ were used at the final concentration of 10 ng/mL

and BBR was used at 100 μmol/L. The transepithelial electrical resistance (TER) was measured with a Volt-Ohm Meter at 0

6

12

24

36 and 48 h after treatment. Both Western blot analysis  and immunofluorescence assay were used to analyze the tight junction protein occludin. The protein expression of myosin light chain (MLC) and phosphorylated MLC (pMLC) was analyzed by Western blot analysis.       Results        The TER had no significant change in the control group and BBR group after treatment. In the TNF-α + IFN-γ group

TER decreased gradually after treatment

and was significantly lower at 12

24

36 and 48 h than that before treatment (P0.05). In the TNF-α + IFN-γ + BBR group

TER also decreased gradually after treatment

but was significantly higher than that in the TNF-α + IFN-γ group at 12

24

36 and 48 h after treatment (P0.05). The protein expression of occludin in each group did not change significantly after treatment (P0.05). However

the remarkable morphological relocalization with expanded intracellular pools of occludin was observed in the TNF-α + IFN-γ group

which was attenuated obviously in the TNF-α + IFN-γ + BBR group. The pMLC protein expression in the TNF-α + IFN-γ group was significantly higher than that in other 3 groups (P0.05).       Conclusion        BBR alleviates intestinal epithelial barrier disruption during inflammation by reducing MLC phosphorylation level and attenuating the morphological relocalization of tight junction protein occludin.