Association of intestinal epithelial tight junctions, E.coli, intestinal mucosa Toll-like receptor-4 and tumor necrosis factor-alpha in rabbit with non-alcoholic fatty liver disease

Abstract

To explore the variation and association of intestinal epithelial tight junctions, E.coli, and expression of Toll-like receptor-4 (TLR-4) and tumor necrosis factor-alpha (TNFα) in a rabbit model of non-alcoholic fatty liver disease (NAFLD). Fourteen male New Zealand rabbits were randomly divided into two groups. The control group was given a normal diet, while the NAFLD group was given a high-fat diet. After 12 weeks, the two groups were sacrificed. Both length and width of the tight junctions of ileum epithelial cells were measured by electron microscopy. Enzyme-linked immunosorbent assay was used to detect the concentration of TNFα in venous blood serum. Location and expression of TLR-4 were observed by immunohistochemical staining. Copies of E.coli genes were measured by RT-PCR. The relationship between TNFα and tight junctions, TLR-4, and E.coli were respectively analyzed by stepwise multiple linear regression. Compared with the control group, the NAFLD group has significantly shortened ileum epithelial fight junctions (t=5.031, P<0.01), increased copies of E. coli genes (t=-3.492, P<0.01), and increased ileal expression of TLR-4 (t=-44.089, P<0.01). A significant increase of TNFα was also observed in the NAFLD group (t=-17.768, P<0.01). Regression analysis showed that E.coli and intestinal epithelial tight junctions were correlated (standardized beta=-0.385), and showed a positive correlation between E. coli and TLR-4 (standardized beta=0.332 and 0.427). Damage to the intestine as a physical barrier, biological barrier and immune barrier is closely related to TNFα expression, and the relation between the immune barrier and TNFα is more significant.