| ObjectiveTo establish a practical and reproducible animal model of acute-on-chronic liver failure, which is similar to the pathology and chemistry in human beings, in order to provide the basis for study of pathophysiologic mechanism in patients with acute-on-chronic liver failure, as well as drug screening and evaluation. Materials and MethodsPart I Exploration of Establishing rat model of ACLF in human serum albumin-induced cirrhosis or liver fibrosis(1) Immunological hepatic fibrosis was induced by administration of human serum albumin in Wistar rats.The extent of liver fibrosis was determined by liver biopsy after injection through tail vein for 6 weeks.(2) Twenty-four healthy female Wistar rats were randomly divided into 4 groups (n = 6). D-galactosamine was intraperitoneally administered at the dose of 1.2 g/kg in group 1. lipopolysaccharide (30 mg/kg) were intravenous injected with in group 2. In group 3, lipopolysaccharide (25μg/kg) was administered 8 days after intravenous injection of BCG (2 x 108 live, weakened bacteria), while D-galactosamine (400 mg/kg) and lipopolysaccharide (100μg/kg) were simultaneously injected in group 4. Survival time was observed, and liver injury was assessed by histopathology .(3) Twenty-two Wistar rats with immunological liver fibrosis were divided into 3 groups 5 days after liver biopsy. D-galactosamine (1.2 g/kg) was intraperitoneally administered in group 1 (n = 6). Rats in group 2 (n = 6) were treated with lipopolysaccharide (30 mg/kg). D-galactosamine (400 mg/kg) and lipopolysaccharide (100μg/kg) were simultaneously injected in group 3 (n = 10). Survival time was observed, and liver injury was assessed by histopathology.Part II Experimental comparision in rats with acute-on-chronic liver failure or acute liver failure.Sixty-five rats with immunologic hepatic fibrosis acted as ACLF group, and 50 healthy female Wistar rats as AHF group. D-galactosamine (400 mg/kg) and lipopolysaccharide (100μg/kg) were intraperitoneally administered in the two groups. Ten rats in ACLF group and 6 rats in AHF group were sacrificed at0, 4, 8, and 12 hours, respectively. Blood were taken for liver function tests and plasma cytokine levels. The TLR4 mRNA expression and dynamic pathology were analyzed in liver specimens. And cell apoptosis was detected by tunnel assay. Mortality and survival time were recorded in another 20 rats.Results(1) Hepatic fibrosis was detected after albumin intravenous injection for 6 weeks. Acute liver failure was pathologically diagnosed in D-galactosamine group and D-galactosamine/lipopolysaccharide group. Rats in BCG + lipopolysaccharide group failed to exhibit specific liver injury. In lipopolysaccharide group, histopathology confirmed activation of Kupffer cells in liver.(2) We treated cirrhotic rats with D-galsctosamine,lipopolysaccharide,and D-galactosamine/lipopolysaccharide,respectively. After treatment, 5 rats died in group 1, with survival time of 39 to 52 hours. Histopathology revealed severely adipose degeneration in regenerative nodules,only pelleta necrosis were seen. In group 2, rats experienced lethargy,febrile shaking and diarrhea, with fully recovery after 24 hours,motility was observed.Three rats were sacrificed on 3 days, with no signs of necrosis in liver section. In group 3, 5 rats died from severe liver failure, with survival time of 13~19 hours. Histology of liver section revealed massive necrosis in nodules, with significant apoptosis of heaptocytes.(3) Mortality rates were 88.0% and 58.3%, respectively, in rats with ACLF and acute liver failure, with mean survival time of 15.6±1.8 hours, and 16.1±3.7 hours, respectively. Index of apoptosis was significantly higher in ACLF group at each time points than group of acute liver failure.Compared with those in group of acute liver failure, plasma TNF-αlevels were significantly lower and arrived itspeak later , while plasma IL-10 levels were higher in ACLF group 8 hours after treatment . TLR4 mRNA expression in liver specimens were correlated with plasma TNF-αlevels in both groups.Conclusion(1) The rat model of acute-on-chronic liver failure, induced by D-galactosamine /lipopolysaccharide in rats with immunological liver fibrosis, showed similar morphological changes as human beings,While D-galactosamine or lipopolysaccharide alone failed to sacrifice cirrhosis rats from liver massive necrosis.(2) The high mortality rate seen in ACLF rats, compared with that of acute liver failure, might be related to more significant apoptosis, different profiles of inflammatory cytokine, as well as different pathology.(3) The rat model of acute-on-chronic liver failure can be used in drug study,for its repeatability and stability.
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