The protective or damaging effect of Tumor necrosis factor-α in acute liver injury is concentration-dependent

Yulong Dong, Yuzhou Liu, Xingrui Kou, Yingying Jing, Kai Sun, Dandan Sheng, Guofeng Yu, Dandan Yu, Qiudong Zhao, Xue Zhao, Rong Li, Mengchao Wu, Lixin Wei

Inflammatory cytokine is important in modulating injured diseases. Tumor necrosis factor-α (TNF-α), one of potent inflammatory cytokines, plays a dominant role in host defense reaction. However, the concrete effect of TNF-α on acute liver injury is totally unclear. Here we reported the concrete effect and possible mechanisms of TNF-α on acute liver injury induced by carbon tetrachloride (CCl4). SD male rats were equally divided into nine groups. CCl4 (1 ml/kg) was subcutaneously injected into the rats. Enbrel, a TNF-α inhibitor, were intraperitoneally injected at dose of 0, 0.25, 0.5, 1, 2, 4 or 8 mg/kg 15 min before the CCl4 injection. 24 h later, rats were sacrificed. Serum ALT and AST were measured with an autoanalyzer. Serum TNF-α were measured by ELISA. HE staining was used to observe the liver tissue morphology. Hepatocellular apoptosis were tested by immunochemistry and Tunnel kit. Inflammatory factors, involve IL-4, IL-6, IL-8, IL-β and IFN-γ were detected by RT-PCR. The NF-κB signal pathway and anti-apoptotic genes include Bcl-XL, FHC, XIAP and Bcl-2 were measured by western-blotting and RT-PCR. The change of liver function presented an obvious "V" shape in the whole process of persistently increased Enbrel. As Enbrel was increased gradually from 0 to 1 mg/kg, serum TNF-α were blocked, ALT and AST were gradually decreased as TNF-α as well as the numbers of hepatocellular apoptosis, and were declined to the minimum at 1 mg/kg Enbrel. As Enbrel was increased gradually from 1 to 8 mg/kg, ALT, AST and hepatocellular apoptosis were increased instead, and reached to the maximum at 8 mg/kg Enbrel. HE showed that the seriousness of hepatocellular steatosis was the most at 8 mg/kg Enbrel, and second at 0 mg/kg, the weakest at 1 mg/kg in the acute liver injury. Western-blotting and RT-PCR showed NF-κB, p-IκBα and antiapoptotic genes include Bcl-XL, FHC, XIAP, Bcl-2 were decreased as TNF-α was blocked by increased Enbrel. Our results suggested that TNF-α had a dual role in acute liver injury. It was regulated might via the corporate effect of NF-κB signal pawahway and anti-apoptosis. Meanwhile, our findings provide a reference for clinical treatment of acute liver injury.