RESUMEN
Objective To study the impact of tumor necrosis factor-α (TNF-α) and its antagonist on the expressions of intestinal mucosa claudin-1,Zonula Occludens-1 (ZO-1) and myosin light chain kinase (MLCK) in rat models of acute liver failure.Methods Fifty four healthy male SpragueDawley (SD) rats were randomly divided into normal control group,model group and intervention group according to a random number table.Rats in normal control (n=6) group were intraperitoneally injected with 0.9％ saline (12 mL/kg).Rats in model group (n=24) and intervention group (n=24) were intraperitoneally injected with a full dose of D-galactosamine (D-GalN) at a dose of 1 200 mg/kg to establish model of acute liver failure,while rats in intervention group were intraperitoneally injected with TNF-α antagonists (rhTNFR∶Fc) at a dose of 12.5 mg/kg before 24 hours given D-GalN.At each time point of hour 8,24,48 and 72,six rats in both model group and the intervention group were sacrificed,respectively,while the normal control group were all anesthetized and sacrificed at 72 h.Models were repeated five times.Serum liver function was detected by biochemical method,and serum TNF-α level was detected by enzyme-linked immunosorbent assay (ELISA).Hematoxylin-eosin (HE) stained sections of liver and terminal ileum were examined under an optical microscope for pathological changes;and protein expression of the terminal ileum Claudin-1,ZO-1 protein and MLCK were determined by immunohistochemistry and Western blot.Means among groups were compared with t test.Results Acute liver failure was successfully induced in the D-GalN injected rats.In the model group,alanine aminotransferase (ALT) began to decline,total bilirubin continued to rise,and enzyme-jaundice separation developed at hour 72.But total bilirubin in intervention group at hour 72 was decreased.Light microscope showed that at hour 72,villus lodged at terminal ileum in the model group with part of villus tip failing off in the model group.Villus mucosa and submucosa interstitial were edema and infiltrated with numerous neutrophils.The terminal ileum kept integrate in the intervention group,and villus mucosa and submucosa were mild edema and only infiltrated with a small amount of neutrophil.Expressions of tumor necrosis necrosis factor (TNF)-α in rats of model group and intervention group were gradually increased and peaked at hour 24 ([239.83 ± 15.81] and [182.71± 17.08] ng/L,respectively),which were significantly higher than that of the control group ([24.19±3.57] ng/L,t=22.68and 15.73,respectively;both P＜0.01).Expression of serumTNF-α in the intervention group was significantly lower than that of model group (t=4.58,P＜0.01).Expressions of Claudin-1 and ZO-1 in model group decreased gradually at an early stage and reached the lowest level at hour 24 (0.355 ± 0.068 and 0.387 ± 0.091,respectively),which were both significantly lower than that of control group (1.640±0.188 and 1.015±0.150,respectively;t=12.87 and 7.14,respectively;both P＜0.01).In the intervention group,expressions of Claudin-1 and ZO-1 also decreased to the lowest level at hour 24 (1.051 ± 0.370 and 0.642 ± 0.082,respectivley),which were both significantly lower than that of control group (t =2.84 and 4.36,respectively;both P＜0.05),but significantly higher than model group with stastically difference (t =3.70 and 4.15,respectively;both P＜0.01).MLCK protein levels in the model and intervention group were gradually increased,which peaked at hour 24 (1.298±0.194 and 1.033 ± 0.073,respectively),significantly higher than the control group (0.460±0.069,t=8.16 and 11.44,both P＜0.01);and MLCK in the intervention group was lower than that in the model group with statistically difference (t=2.56,P＜0.05).Conclusions Expression of serum TNF-α in rat model of acute liver failure increases,which leads to decreased expression of Claudin-1 and ZO-1,and increased expression of MLCK,makes cell shrunk and cell gap increased.TNF-α antagonist could significantly reduce the inflammation and liver cell apoptosis,improve liver function by inhibiting MLCK expression and preventing decrease of Claudin-1 and ZO-1 proteins.