Stadler J, Bentz B G, Harbrecht B G, Di Silvio M, Curran R D, Billiar T R, Hoffman R A, Simmons R L
Department of Surgery, University of Pittsburgh, Pennsylvania 15261.
Ann Surg. 1992 Nov;216(5):539-46. doi: 10.1097/00000658-199211000-00003.
Although direct cytotoxicity is a well-established phenomenon of tumor necrosis factor alpha (TNF alpha)-induced tissue damage, the intracellular events leading to cell death are still poorly understood. To study the cytotoxic effects of TNF alpha on normal parenchymal cells, rat hepatocytes were purified and incubated with various concentrations of TNF alpha. Mitochondrial respiration, total protein synthesis, and enzyme release were measured to assess metabolic performance and cell integrity. Treatment with TNF alpha suppressed mitochondrial respiration in a concentration-dependent fashion, resulting in a reduction of the activity of complex I of the respiratory chain to 67.0 +/- 3.5% of that of untreated hepatocytes by 2000 U/mL TNF alpha. Under these conditions protein synthesis and the release of intracellular enzymes were significantly increased. Both hepatocellular enzyme release and inhibition of mitochondrial respiration appear to be associated with the generation of reactive oxygen intermediates by the hepatocyte itself, because oxygen radical scavengers prevented these adverse effects of TNF alpha. Inhibition of protein synthesis by cycloheximide as well as addition of cyclic adenosine monophosphate synergistically enhanced the suppression of mitochondrial respiration by TNF alpha, resulting in complex I activity of 6.9 +/- 1.6% and 24.9 +/- 2.9% of that of untreated cells. These data indicate that inhibition of mitochondrial respiration is one of the mechanisms by which TNF alpha induces tissue injury.
尽管直接细胞毒性是肿瘤坏死因子α（TNFα）诱导组织损伤的一种公认现象，但导致细胞死亡的细胞内事件仍知之甚少。为了研究TNFα对正常实质细胞的细胞毒性作用，纯化大鼠肝细胞并与不同浓度的TNFα孵育。测量线粒体呼吸、总蛋白质合成和酶释放以评估代谢性能和细胞完整性。用TNFα处理以浓度依赖性方式抑制线粒体呼吸，2000 U/mL TNFα使呼吸链复合体I的活性降低至未处理肝细胞的67.0±3.5%。在这些条件下，蛋白质合成和细胞内酶的释放显著增加。肝细胞酶释放和线粒体呼吸抑制似乎都与肝细胞自身产生活性氧中间体有关，因为氧自由基清除剂可防止TNFα的这些不利影响。放线菌酮抑制蛋白质合成以及添加环磷酸腺苷可协同增强TNFα对线粒体呼吸的抑制作用，导致复合体I活性分别为未处理细胞的6.9±1.6%和24.9±2.9%。这些数据表明，线粒体呼吸抑制是TNFα诱导组织损伤的机制之一。
