Milk fat globule-EGF factor Ⅷ attenuates apoptosis and permeability damage of the intestinal mucosa in rats with obstructive jaundice

Abstract:

Objective To investigate the level of milk fat globule-EGF factor Ⅷ（MFG-E8） in plasma and the expression of MFG-E8 protein in the small intestine in rats with obstructive jaundice，and to determine whether supplementation of MFG-E8 can reduce apoptosis and permeability damage of the intestinal mucosa in rats with obstructive jaundice.Methods The rat model of obstructive jaundice was established by common bile duct ligation（BDL）. Thirty-two male adult SD rats were randomly divided into sham operation group（sham group），obstructive jaundice group（BDL group），MFG-E8 treatment group（MFG-E8 group），and treatment control group（vehicle group）. The MFG-E8 group and vehicle group were intraperitoneally injected with MFG-E8（20 μg/kg ） or an equal volume of normal saline on the 1st，3rd，and 5th days after BDL. Blood and tissue samples were collected on the 7th day after modeling. Western blot was used to determine plasma MFG-E8 levels，intestinal MFG-E8 protein expression，and intestinal cleaved caspase-3 levels. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay was used to observe the apoptosis of intestinal cells. Fluorescein isothiocyanate-dextran（FITC-D） was used to assess intestinal mucosal permeability. Enzyme-linked immunosorbent assay was used to determine plasma tumor necrosis factor alpha（TNF-α） levels.Results Compared with the sham group，the BDL group had significantly decreased plasma MFG-E8 level and MFG-E8 protein expression level in the small intestine（5.675±0.638 vs. 3.087±0.272，P=0.001；1.24±0.157 vs. 0.484±0.090，P=0.000）. Compared with the vehicle group，the MFG-E8 group had significantly decreased apoptosis ratio of small intestinal cells and expression of cleaved caspase-3 protein（22.333±5.085 vs. 14.467±3.722，P=0.048； 0.887±0.132 vs. 0.582±0.145，P=0.024）. The FITC-D and plasma TNF-α levels in the vehicle group were significantly higher than those in the sham group（4.515±0.601 vs. 1.519±0.346，P=0.000；233.84±21.21 vs. 78.24±13.75，P=0.000）. The FITC-D level in the MFG-E8 group（2.826±0.588） was significantly lower than that in the vehicle group（P=0.000）. Compared with the vehicle group，the plasma level of TNF-α（109.90±24.06） in the MFG-E8 group was significantly decreased by 53%（P=0.000）.Conclusion MFG-E8 supplementation significantly attenuates apoptosis and permeability damage of the intestinal mucosa，as well as systemic inflammatory responses in rats with obstructive jaundice.