Reduced expression of intestinal epithelial tight junction protein claudin-1 in mice with fulminant hepatic failure

Abstract

Objective To explore the expression change of intestinal epithelial tight junction (IJ)protein claudin-1 in mice with fulminant hepatic failure (FHF).Methods FHF was induced with a method that combined intraperitoneal injection of lipopolysaccharide (LPS,10 mg/kg) and D-galactosamine (GalN,800 mg/kg).Control saline (2 ml/kg,ip),LPS (10 mg/kg,ip) and GaIN (800 mg/kg,ip) were also detected.The effect of administration of anti-tumor necrosis factor alpha (TNF-α) IgG antibody (anti-TNF-α IgG,100 μg/per) on the level of TNF-α was assessed before administration of D-galactosamine/lipopolysaccharide.At the 2nd h,6th h,9th h,12th h,24th h after injection in FHF group,the 9th h after injection in control groups and 9th h after injection in anti-TNF-α IgG group,the mice were killed for the collection of large intestine specimens.Claudin-1 was analyzed with immunohistochemistry,Western blotting,and real-time quantitative PCR.Results Tight junction protein claudin-1 was localized along the apical region of the lateral plasma membrane representing the region of tight junctions in surface and crypt epithelial cells.Weakly distributed density of claudin-1 in intestinal mucosa was found in mice with FHF from the 9th h after injection.Compared to saline group,Western blotting analysis demonstrated markedly reduced claudin-1 expression in mice with FHF at the 6th h and 9th h after injection (6th h:0.8600±0.0208 vs 1.0,P ＜0.05; 9th h:0.6633 ±0.0328 vs 1.0,P ＜0.01).Furthermore,the expression of claudin-1 mRNA was markedly reduced at the 6th h,9th h,and 12th h after injection in mice with FHF (6th h:0.3067 ±0.1291 vs 1.0,P ＜0.05; 9th h:0.2233 ±0.1155 vs 1.0,P ＜0.01 ; 12th h:0.5275 ±0.1222 vs 1.0,P ＜0.05).Compared to saline group,no significant difference in claudin-1 expression was found with prophylactic treatment with anti-TNF-α-IgG antibody in mice with FHF at the 9th h after injection (protein:0.9533 ±0.0186 vs 1.0,P ＞0.05; mRNA:0.85 ±0.1437 vs 1.0,P ＞0.05).Conclusions The expression of tight junction protein claudin-1 was reduced at both protein and mRNA levels in intestinal epithelial cells that were induced by TNF-α in mice model of FHF. Key words: Liver failure; Intestines/cytology; Epithelial cells/pathology; Epithelial cells/metabolism; Connexins/metabolism; Mice