Kupffer细胞在内毒素诱导肝损伤发病机制中的作用

Role of triggering receptor expressed on myeloid cells-1 in liver injury in rats with acute necrotizing pancreatitis

AIM: To investigate the expression of triggering receptor expressed on myeloid cells-1 (TREM-1) in liver injury with acute necrotizing pancreatitis (ANP) and to explore the correlation between TREM-1 expression and liver injury in rats with ANP.

METHODS: Forty-eight male Sprague-Dawley rats were randomly divided into two groups: a control group and an ANP group. ANP was induced by retrograde injection of 5% sodium taurocholate into the biliary pancreatic duct. Rats were sacrificed at 3, 6, 12 and 24 h after treatment. Serum amylase (AMY), alanine aminotransferase (ALT), aspartate aminotransferase (AST), sTREM-1 and interleukin-1β (IL-1β) were measured. The pathologic changes of the pancreatic and hepatic tissues were observed and graded under a microscope. The expression of TREM-1 mRNA in the liver was detected by real-time quantitative (qRT) PCR.

RESULTS: The levels of serum amylase, sTREM-1 and IL-1β began to increase at 3 h after sodium taurocholate injection, and were then maintained at high levels at all subsequent time points, significantly higher than those in the control group (P < 0.05). The level of sTREM-1 in the ANP group was correlated with Schmidt score (r = 0.481, P < 0.05). Serum ALT and AST concentrations at 6, 12 and 24 h, the pathologic scores of pancreatic and liver tissues, and the expression of TREM-1 mRNA (3 h: 1.96 ± 0.63 vs 0.94 ± 0.23; 6 h: 4.46 ± 1.42 vs 0.95 ± 0.24; 12 h: 2.59 ± 1.14 vs 1.10 ± 0.33; 24 h: 2.56 ± 1.08 vs 0.85 ± 0.27) in the liver were significantly higher in the ANP group than in the control group (P < 0.05 for all).

CONCLUSION: The expression of TREM-1 mRNA in liver tissue and the level of serum sTREM-1 increase significantly in rats with ANP, suggesting that TREM-1 may play an important role in ANP with liver injury.

Protective effects of N-acetylcysteine against liver injury in rats with severe acute pancreatitis

AIM: To investigate the role of nuclear factor-kappa B (NF-κB) activation in liver injury in rats with severe acute pancreatitis (SAP), and to explore the protective effect of N-acetylcysteine (NAC) against SAP-associated liver injury in rats.

METHODS: Forty-two Wistar male rats were divided into sham operation group (SO, n = 6), SAP group (n = 18), and SAP + NAC group (NAC, 300 mg/kg body wt, n = 18). SO group underwent laparotomy only. SAP model was established by retrograde injection of 50 g/L sodium taurocholate into the bili-pancreatic duct in Wistar rats. SAP + NAC group were given NAC 300 mg/kg body weight intaperitoneally 2 h before SAP model was established. Rats were sacrificed at 3, 6 and 12 h after operation. The liver and pancreas tissues were obtained to observe their pathological changes with light microscopy. The levels of serum ALT and AST were determined at three time points (8 rats for each time point). The expression of TNF-α mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR). The activity of NF-κB in liver was examined by immunohistochemical methods.

RESULTS: The levels of serum ALT and AST increased significantly in SAP group as compared with those in SO group at 3, 6 and 12 h (ALT: 186.67 ± 27.28, 321.17 ± 56.14, 492.50 ± 69.77 vs 36.83 ± 7.02; AST: 255.50 ± 44.15, 343.17 ± 43.70, 425.33 ± 58.37 vs 41.67 ± 5.35; P < 0.05 or 0.01). The level of TNF-α mRNA in SAP group was significantly higher than that in SO group at 3, 6 and 12 h (0.37 ± 0.03, 0.77 ± 0.04, 0.54 ± 0.04 vs 0.24 ± 0.03; P < 0.05 or 0.01). The activity of NF-κB was also higher in SAP group than that in SO group at 3 or 6 h (51.95 ± 4.76, 24.67 ± 4.93 vs 9.33 ± 2.05; P < 0.01 or 0.05). Liver and pancreas pathological damages were more severe in SAP group than those in SO group under light microscope. In SAP + NAC group, the levels of serum ALT and AST (143.67 ± 16.62, 203.33 ± 25.41, 301.17 ± 26.82; 136.33 ± 26.27, 221.50 ± 38.31, 310.50 ± 38.17) decreased significantly in comparison with those in SAP group (P < 0.05 or 0.01), and the expression of TNF-α mRNA was significantly lower than that in SAP group at the three time points (0.25 ± 0.03, 0.50 ± 0.05, 0.43 ± 0.03, P < 0.05 or 0.01). The activity of NF-κB in SAP + NAC group was lower than that in SAP group at 3 or 6 h (37.60 ± 6.37, 12.88 ± 2.66, P < 0.05).

CONCLUSION: NF-κB activation and TNF-α mRNA up-regulation involve in the pathogenesis of liver injury in SAP rats. NAC at a dose of 300 mg/kg can alleviate the pathological damage to liver, and its mechanism might relate to inhibition of NF-κB activation and reduction of cytokines such as TNF-α.