[The study on bacteria invading the intestinal mucosa barrier in mice with fulminant hepatic failure]

To explore the mechanism of fulminate hepatic failure (FHF) complicated with spontaneous peritonitis (SBP) through the research of bacteria invading the intestinal mucosa barrier.

240 BalB/c male mice were divided into four groups as isotonic NS group (n = 40), lipopolysaccharide (LPS) group (n = 40), galactosamine (GalN) group (n = 40) and FHF model group (n = 120). Each mouse received same volume of NS, LPS (10 ug/kg), GalN (800 mg/kg) or LPS (10 ug/kg)/GalN (800 mg/kg) intraperitoneal injection according to its group. 8 mice were executed at 2, 6, 9, 12 and 24 hours after injection, respectively, and the liver and intestinal tissue samples were taken at the same time. ALT was measured by automatic biochemical analyzer and was compared between groups using Mann-Whitney U test. Liver and intestinal tissue received HE staining. The ultrastructure of intestinal mucosa and the method by which bacteria invaded the intestinal mucosa were observed by transmission electron microscopy. All data were analyzed by SPSS13.0 statistic software.

ALT level, results of hepatic pathology, mortality and clinical manifestations of mice in the FHF model group met the diagnostic criteria of FHF. Intestinal tissue was found with slight edema and little inflammatory cells infiltration through HE staining in all the 4 groups of mice 9 hours after injection. Microvilli were found broken, shed and shorten in the intestinal epithelial cells with incomplete tight junction (TJs) and obviously changed organelles in the FHF model group of mice observed by transmission electron microscope. Mass hemorrhagic necrosis of liver cells with remnant liver cells swelling and many inflammatory cells infiltration by HE staining in the FHF model group. But the changes in hepatic pathology and intestinal mucosa ultrastructure were not so obvious in the mice of NS, LPS and GalN groups. Bacteria penetrated the intestinal wall by pinocytosis 6 to 9 hours after injection in the FHF model group, the microvilli were broken off and TJs turned rupture in the areas that the bacteria penetrated. The bacteria were found in the form of cyst 12 hours after injection.

LPS (10 mg/kg)/GalN (800 mg/kg) combined injection was successful in establishing the FHF mice model. The rupture of TJs may provide conditions for intestinal bacteria to penetrate the intestinal mucosa in FHF. Rupture of TJs may be one of the reasons why FHF was complicated with SBP.