Tumor necrosis factor-alpha induces apoptosis of enterocytes in mice with fulminant hepatic failure

AIM: To explore the alterations of intestinal mucosa morphology, and the effects of tumor necrosis factor α (TNFα) on enterocyte apoptosis in mice with fulminant hepatic failure (FHF).METHODS: Liver damage was induced by lipopolysaccharide(LPS)/TNF-α in D-galactosamine (GalN) sensitized BALB/c mice. There were 40 mice in normal saline (NS)-treated group, 40 mice in LPS-treatedl group, 40 mice in GaiN-treated group, 120 mice in GalN/LPS-treated group and 120 mice in GalN/TNFα-treated group. Each group was divided into five subgroups of eight mice each. Serum samples and liver, intestinal tissues were respectively obtained at 2, 6, 9, 12 and 24 h after administration. Anti-TNFα monoclonal antibody was injected intravenously into GalN/LPS-treated mice. Serum TNFα levels were determined by enzymelinked immunosorbent assays (ELISA). Serum ALT levels were determined using an automatic analyzer. The intestinal tissues were studied under light microscope and electron microscope at 2, 6, 9, 12 and 24 h in mice with fulminant hepatic failure, respectively. Enterocyte apoptosis was determined by terminal deoxynucleotidyl transferasemediated dUTP nick-end labeling (TUNEL) method. The expression of tumor necrosis factor receptor 1 (TNFR1) in intestinal tissue was tested by immunohistochemistry Envision Two Steps.RESULTS: Gut mucosa was morphologically normal at all time points in all groups, but typical apoptotic cells could be seen in all experimental groups under electron microscope. Apoptosis rate of gut mucosal epithelial cells were significantly increased at 6, 9 and 12 h, peaked at 12 h in mice with fulminant hepatic failure. TNFα induced apoptosis of enterocytes in mice with FHF. The integrated OD (IOD) levels of TNFα receptor 1 protein expressed in the intestine of mice with GalN/LPS and GalN/TNFαinduced FHF at 2, 6, 9, 12 and 24 h after GalN/LPS and GalN/TNFα administration were 169.54±52.62/905.79±111.84, 11 350.67±2 133.26/28 160.37±4 601.67, 25 781.00 ±2 277.75/122 352.30±49 412.40, 5 241.53±3 007.24/49 157.93±9 804.88, 7 086.13±1 031.15/3 283.45±127.67,respectively, compared with those in control groups (with NS, LPS and GalN administration, respectively). IOD level of TNFR1 changed significantly at 6, 9 and 12 h after GalN/LPS and GalN/TNFα administration. The expression of TNFR1 protein was significantly higher at g h after GalN/LPS and GalN/TNFα administration than that in control groups. Protein expression of TNFR1 was positively correlated with enterocyte apoptosis. CONCLUSION: TNFα can induce apoptosis of enterocytes in mice with FHF. Anti-TNFα IgG can inhibit this role.

AIM: To explore the alterations of intestinal mucosa morphology, and the effects of tumor necrosis factor a (TNFα) on enterocyte apoptosis in mice with fulminant hepatic failure (FHF). METHODS: Liver damage was induced by lipopolysaccharide (LPS)/TNF-α in D-galactosamine (GaIN) sensitized BALB/c mice. There were 40 mice in normal saline (NS)-treated group, 40 mice in LPS-treated group, 40 mice in GaIN-treated group, 120 mice in GaIN/ LPS-treated group and 120 mice in GaIN/ TNFα-treated group. Each group was divided into five subgroups of eight mice each. Serum samples and liver, intestinal tissues were respectively obtained at 2, 6,9,12 and 24 h after administration. Anti-TNFa monoclonal antibody was injected intravenously into GaIN/LPS-treated mice. Serum TNFα levels were determined by enzyme linked immunosorbent assays (ELISA). Serum ALT levels were determined using an automatic analyzer. The intestinal tissues were studied under light microscope and electron microscope at 2, 6, 9,12 and 24 h in mice with fulminant hepatic failure, respectively. Enterocyte apoptosis was determined by terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling (TUNEL) method. The expression of tumor necrosis factor receptor 1 (TNFR1) in intestinal tissue was tested by immunohistochemistry Envision Two Steps. RESULTS: Gut mucosa was morphologically normal at all time points in all groups, but typical apoptotic cells could be seen in all experimental groups under electron microscope. Apoptosis rate of gut mucosal epithelial cells were significantly increased at 6, 9 and 12 h, peaked at 12 h in mice with fulminant hepatic failure. TNFa induced apoptosis of enterocytes in mice with FHF. The integrated OD (IOD) levels of TNFa receptor 1 protein expressed in the intestine of mice with GaIN/LPS and GaIN/ TNFα induced FHF at 2, 6, 9, 12 and 24 h after GaIN/LPS and GaIN/TNFα administration were 169.54±52.62/905.79±111.84,11 350.67±2 133.26/28 160.37±4 601.67, 25 781.00±2 277.75/122 352.30±49 412.40, 5 241.53±3 007.24/ 49 157.93±9 804.88, 7 086.13±1 031.15/3 283.45±127.67, respectively, compared with those in control groups (with NS, LPS and GaIN administration, respectively). IOD level of TNFR1 changed significantly at 6, 9 and 12 h after GaIN/LPS and GalN/TNFa administration. The expression of TNFR1 protein was significantly higher at 9 h after GaIN/LPS and GaIN/TNFα administration than that in control groups. Protein expression of TNFR1 was positively correlated with enterocyte apoptosis. CONCLUSION: TNFα can induce apoptosis of enterocytes in mice with FHF. Anti-TNFα IgG can inhibit this role.