Mechanism research on intestinal bacterial translocation in rats with liver cirrhosis after partial hepatectomy

Objective To investigate the mechanism of intestinal bacterial translocation in rats with liver cirrhosis after partial hepatectomy. Methods Forty healthy spelific pathogen free male Sprague-Dawley (SD) rats [4 weeks old, average weight: (90±10)g] were randomly divided into sham operation group (SO group) and partial hepatectomy group (PH group) with 20 rats in each group after liver cirrhosis model was established. Rats in SO group underwent separation of perihepatic ligaments then the abdomen was closed. Rats in PH group underwent modified partial hepatectomy including resection of left medial lobe, lateral lobe and middle lobe. The volume of resected liver was about 2/3. Portal pressure was tested in 10 rats from each group 24 h after operation. The levels of plasma D-lactate, endotoxin, content of bacteria in mesenteric lymph nodes, histological change of small intestinal mucosa, contents of tight junction protein ZO-1 and Claudin-1 of small intestinal tissue, expressions of tumor necrosis factor (TNF)-α, interferon (IFN)- γ, myosin light chain kinase (MLCK) of small intestinal tissues, changes of fecal flora were tested in the other 10 rats of each group 24 h after operation. The experimental data with normal distribution in 2 groups were compared using t test. The Chiu's scores of small intestinal mucosa in 2 groups were expressed in M(Q25, Q75) and were compared using rank sum test. The comparison of rates in 2 groups was conducted using Chi-square test. Results The portal pressure in PH group [(22.9±0.7)cmH2O] (1 cmH2O=0.098 kPa) was significantly higher than that in SO group [(15.4±1.1)cmH2O] (t= -11.15, P<0.05). The level of plasma endotoxin in PH group [(52.6±2.3)EU/ml] increased obviously, compared with that in SO group [(48.6±2.4)EU/ml] (t= -3.31, P<0.05) . The content of bacteria in mesenteric lymph nodes in PH group was (162±55)% of that in SO group, which was significantly higher than that in SO group (t= -2.22, P<0.05). The level of plasma D-lactate was (60.6±5.0)mg/L in PH group, which was significantly higher than that in SO group [(37.4±2.8)mg/L] (t= -9.70, P<0.05). The median of Chiu's score of small intestinal mucosa was 4(3, 4) in PH group, which was significantly higher than that in SO group [1(1, 2)] (Z= -3.52, P<0.05). The contents of tight junction protein ZO-1 and Claudin-1 of small intestinal tissue in PH group were 0.50±0.14, 0.33±0.13 respectively, which were significantly lower than those in SO group (0.70±0.09, 0.62±0.10) (t=2.78, 2.98; P<0.05). The strong positive expression rates of TNF-α, IFN-γ, MLCK were 50%(5/10), 40%(4/10), 70%(7/10) in PH group, which were significantly higher than those in SO group [20%(2/10), 10%(1/10), 20%(2/10)] (χ2=4.87, 8.37, 5.01; P<0.05). The contents of fecal Escherichia coli, Bacteroides, Fusobacterium, Klebsiella pneumoniae, Bifidobacteria in PH group were (288±74)%, (185±48)%, (278±82)%, (551±96)%, (43±7)% of those in SO group. The contents of fecal Escherichia coli, Bacteroides, Fusobacterium, Klebsiella pneumoniae in PH group were significantly higher than those in SO group, while the content of Bifidobacteria was significantly lower (t=2.49, 3.68, 2.24, 5.50, -3.89; P<0.05). Conclusions The mechanism of intestinal bacterial translocation in rats with liver cirrhosis after partial hepatectomy may be associated with the damage of intestinal mechanical barrier and bacterial barrier. Reducing the portal pressure and level of inflammatory factor, and correcting the intestinal bacterial imbalance may be effective methods for reducing intestinal bacterial translocation. Key words: Liver cirrhosis; Hepatectomy; Bacterial translocation; Gastrointestinal tract; Infection; Rats