Song Hong-Li, Lü Sa, Liu Pei
Department of Infectious Diseases, Second Affiliated Hospital, China Medical University, Shenyang 110004, China.
Zhonghua Gan Zang Bing Za Zhi. 2005 Apr;13(4):290-3.
To study the role of tumor necrosis factor-alpha (TNFalpha) on enterocyte apoptosis in the experimental model of fulminant hepatic failure (FHF).
Liver damage was induced by lipopolysaccharide (LPS)/TNFalpha in D-galactosamine (GalN) sensitized BALB/c mice. Serum TNFalpha levels were determined by enzyme-linked immunosorbent assays (ELISA). The intestinal tissues were studied micro- and ultra-microscopically at 2 h, 6 h, 9 h, 12 h and 24 h time points in mice with fulminant hepatic failure. Enterocyte apoptosis was determined by TUNEL method. The TNFR I expression in the intestinal tissue was tested by immunohistochemistry.
(1) Gut mucosa was morphologically normal at every time point in all groups, but typical apoptotic cells could be seen in the experimental groups under the electron microscope. Apoptosis rate of gut mucosal epithelial cells was significantly increased at 6 h (large intestine: 6.47e(-3)+/-2.91e(-4); small intestine: 6.64e(-3)+/-3.78e(-4)), 9 h (large intestine: 6.81e(+4)+/-7.41e(+3); small intestine: 2.58e(+4)+/-2.28e(+3)) and 12 h (large intestine: 4.92e(+4)+/-9.80e(+3); small intestine: 5.24e(+4)+/-3.01e(+3)), and peaked at 12 h in mice with FHF. (2) TNFalpha induced apoptosis of enterocytes in mice with FHF. Anti-TNFalpha inhibited this effect. (3) The integrated OD (IOD) levels of TNFalpha receptor I protein expressed differently in the intestine of mice with GalN/LPS and GalN/ TNFalpha-induced FHF at 9 h after GalN/LPS and GalN/ TNFalpha administration, in comparison with those of the control groups. IOD level of TNFRI changed significantly at 6 h (large intestine: 2.82e(+4)+/-4.60e(+3); small intestine: 1.14e(+4)+/-2.13e(+3)), 9 h (large intestine: 6.81e(+4)+/-7.41e(+3); small intestine: 2.58e(+4)+/-2.28e(+3)) and 12 (large intestine: 4.92e(+4)+/-9.80e(+3); small intestine: 5.24e(+4)+/-3.01e(+3)) hours after GalN/LPS and GalN/ TNFa administration. The expression of TNFR1 protein was significantly higher at 9 and 12 h after GalN/LPS and GalN/TNFa administration than other time points. Protein expression of TNFR1 was positively correlated with enterocyte apoptosis.
TNFa can induce enterocyte apoptosis in mice with FHF. Anti- TNFalpha IgG can inhibit this role. Excessive TNFRI expression of enterocyte in fulminant hepatic failure can be induced by TNFa, which suggests that TNFalpha can induce apoptosis of enterocyte by up-regulation of TNFRI protein expression.
研究肿瘤坏死因子-α（TNFα）在暴发性肝衰竭（FHF）实验模型中对肠上皮细胞凋亡的作用。
用脂多糖（LPS）/TNFα诱导D-半乳糖胺（GalN）致敏的BALB/c小鼠发生肝损伤。采用酶联免疫吸附测定（ELISA）法测定血清TNFα水平。在暴发性肝衰竭小鼠的2小时、6小时、9小时、12小时和24小时时间点，对肠道组织进行微观和超微观研究。采用TUNEL法测定肠上皮细胞凋亡。用免疫组织化学法检测肠道组织中TNFR I的表达。
（1）所有组在各个时间点的肠道黏膜形态均正常，但在实验组的电子显微镜下可见典型的凋亡细胞。肠道黏膜上皮细胞凋亡率在6小时（大肠：6.47e(-3)±2.91e(-4)；小肠：6.64e(-3)±3.78e(-4)）、9小时（大肠：6.81e(+4)±7.41e(+3)；小肠：2.58e(+4)±2.28e(+3)）和12小时（大肠：4.92e(+4)±9.80e(+3)；小肠：5.24e(+4)±3.01e(+3)）显著升高，并在FHF小鼠中于12小时达到峰值。（2）TNFα诱导FHF小鼠肠上皮细胞凋亡。抗TNFα可抑制此效应。（3）与对照组相比，在给予GalN/LPS和GalN/TNFα后9小时，GalN/LPS和GalN/TNFα诱导的FHF小鼠肠道中TNFα受体I蛋白的积分光密度（IOD）水平表达不同。在给予GalN/LPS和GalN/TNFα后6小时（大肠：2.82e(+4)±4.60e(+3)；小肠：1.14e(+4)±2.13e(+3)）、9小时（大肠：6.81e(+4)±7.41e(+3)；小肠：2.58e(+4)±2.28e(+3)）和12小时（大肠：4.92e(+4)±9.80e(+3)；小肠：5.24e(+4)±3.01e(+3)），TNFR1的IOD水平发生显著变化。在给予GalN/LPS和GalN/TNFα后9小时和12小时，TNFR1蛋白的表达明显高于其他时间点。TNFR1的蛋白表达与肠上皮细胞凋亡呈正相关。
TNFα可诱导FHF小鼠肠上皮细胞凋亡。抗TNFα IgG可抑制此作用。TNFα可诱导暴发性肝衰竭时肠上皮细胞TNFRI表达过度，提示TNFα可通过上调TNFRI蛋白表达诱导肠上皮细胞凋亡。
