ABSTRACT
Background: Disruption of tight junctions between intestinal epithelial cells followed by loss of barrier function is crucial for the pathogenesis and progression of a variety of gastrointestinal disorders.Aims: To investigate the protective effect of ulinastatin on hydrogen peroxide (H2O2)-induced intestinal epithelial barrier disruption.Methods: Model of intestinal epithelial monolayer barrier was established with Caco-2 cells in vitro,and then divided into four groups: blank control group (without any intervention),H2O2 group (500 μmol/L H2O2),low-dose (500 U/mL) and high-dose (3 000 U/mL) ulinastatin groups (ulinastatin + H2O2).Level of malondialdehyde (MDA) and activity of superoxide dismutase (SOD) were detected;transepithelial electrical resistance (TEER) and flux of sodium fluorescein were measured to assess the barrier function;expression and localization of two tight junction proteins,ZO-1 and occludin were evaluated by Western blotting and immunofluorescence;ultrastructure of tight junctions was observed by transmission electron microscopy (TEM).Results: Compared with the blank control group,treatment of Caco-2 cell monolayers with H2O2 resulted in increase in level of MDA,flux of sodium fluorescein and decrease in activity of SOD,TEER and expressions of ZO-1 and occludin (P all ＜0.05).TEM and immunofluorescence showed that the brusher border of Caco-2 cells in H2O2 group was destroyed,the cell-cell junction was vague and the localization of ZO-1 and occludin was discontinuous and the fluorescence intensity was extremely low.While in ulinastatin groups,especially the high-dose group,all the indices above-mentioned were significantly improved (P all ＜0.05).Conclusions: Ulinastatin protects intestinal epithelial monolayer barrier against H2O2-induced disruption at least partially by its antioxidant activity and modulating expression and localization of tight junction proteins.
ABSTRACT
Background:Disruption of intestinal epithelial tight junction and the followed barrier function play important roles in the pathogenesis of intestinal disorders. Curcumin could provide protection for the impaired barrier function. Aims:To investigate the protective effect of curcumin on ethanol-induced intestinal mucosal barrier disruption. Methods:Caco-2 cells were cultured to establish intestinal epithelial cell barrier model in vitro,and then were divided into control group, ethanol group and different concentrations of curcumin groups(5,20,80 μmol/ L curcumin). Trans-epithelial electrical resistance(TEER)and flux of sodium fluorescein for Caco-2 cell monolayers were measured to examine intestinal epithelial barrier function. Expression and localization of Occludin protein were measured by Western blotting and immunofluorescence,respectively. Cell structure was observed by transmission electron microscopy( TEM). Results:Compared with control group,TEER was significantly decreased and flux of sodium fluorescein was significantly increased (P < 0. 05),expression of Occludin protein was significantly decreased(P < 0. 05)in ethanol group. Immunofluorescence showed that Occludin protein expression was discontinuous and fluorescence intensity was low. TEM showed that brusher border was disorganized,and cell-cell junction was vague. When pretreated with curcumin,the above-mentioned indices were significantly improved,especially in 20 μmol/ L curcumin group( P < 0. 05). Conclusions:Curcumin protects ethanol-induced intestinal epithelial cell barrier disruption.