Effects of Ethanol on TNF Cytotoxicity

乙醇对 TNF 细胞毒性的影响

• 批准号: 6605774
• 负责人: JOHN G PASTORINO
• 金额: $ 18.32万
• 依托单位: THOMAS JEFFERSON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6605774
• 关键词: apoptosis; biological signal transduction; cytotoxicity; enzyme activity; ethanol; laboratory rat; liver cells; membrane permeability; mitochondrial membrane; mitogen activated protein kinase; pathologic process; phosphatidylinositol 3 kinase; phosphorylation; tissue /cell culture; tumor necrosis factor alpha

DESCRIPTION (provided by applicant): Ethanol exposure promotes the development of alcoholic liver disease (ALD) but the mechanisms underlying ethanol-induced hepatotoxicity remain poorly understood. An important cellular site manifesting damage brought on by ethanol is the mitochondria. Proinflammatory cytokines such as tumor necrosis factor alpha (TNFalpha or TNF) have been linked to many of the associated damage and repair processes seen in ALD. TNFalpha prompts the opening of the mitochondrial permeability transition pore (MPT). The MPT is the regulatable opening of a large, nonspecific pore across the outer and inner mitochondrial membrane. Development of the MPT has been implicated in both necrotic and some forms of apoptotic cell death. Inhibition of the MPT prevents many of the typical manifestations seen during apoptosis. Liver mitochondria isolated from chronically ethanol fed rats are more susceptible to MPT pore opening induced by various triggers than mitochondria isolated from control animals. In preliminary results we demonstrate an enhancement of TNFalpha cytotoxicity in hepatocytes isolated from chronically ethanol-fed rats compared to their pair-fed controls. Similarly, a 48h exposure of HepG2 cells to ethanol enhanced susceptibility to TNFalpha cytotoxicity. The data suggest that ethanol enhances TNFalpha cytotoxicity, at least in part, by promoting the MPT. The general goals of this project are to investigate the mechanisms by which ethanol potentiates TNFalpha induced cytotoxicity. Our working hypothesis is that ethanol inhibits signaling pathways that protect against TNFalpha cytotoxicity and activates pathways that promote the mitochondrial permeability transition. This theory is supported by our preliminary observations that ethanol inhibits P13-kinase dependent BAD phosphorylation induced by TNFalpha and promotes cell death in a p38 MAPK dependent and caspase 8 independent manner. In addition, ethanol exposure sensitizes mitochondria to the MPT and causes an increase in the levels of the peripheral benzodiazepine receptor, a putative component of the MPT pore. Our SPECIFIC AIMS are to #1) further define the role of ethanol in the alteration of P13-kinase activity and its influence on TNFalpha cytotoxicity and #2) delineate the role and mechanism(s) of activation of p38 MAPK in ethanol plus TNFalpha cytotoxicity; #3) Define the mechanism(s) by which TNF plus ethanol cause the MPT.

描述（由申请人提供）：乙醇暴露促进发育 酒精性肝病（ALD），但乙醇诱导的机制 肝毒性仍然知之甚少。一个重要的细胞部位 乙醇造成的损伤是线粒体。促炎细胞因子 如肿瘤坏死因子α（TNF α或TNF）与许多 酒精中毒中出现的相关损伤和修复过程。TNF α促使 线粒体通透性转换孔（MPT）的开放。MPT是 一个大的，非特异性的孔的可调节的开口，穿过外部和内部 线粒体膜MPT的发展与这两方面都有牵连 坏死和某些形式的凋亡性细胞死亡。抑制MPT可防止 在凋亡过程中看到的许多典型表现。肝线粒体 从长期乙醇喂养的大鼠中分离的MPT孔更容易受到MPT孔的影响。 与从对照分离的线粒体相比，由各种触发物诱导的开放 动物在初步结果中，我们证明了TNF α的增强 从长期乙醇喂养大鼠中分离的肝细胞的细胞毒性比较 配对喂食的对照组类似地，将HepG 2细胞暴露于乙醇48小时， 增强对TNF α细胞毒性的敏感性。数据显示，乙醇 至少部分地通过促进MPT来增强TNF α的细胞毒性。的 本项目的总体目标是研究 乙醇增强TNF α诱导的细胞毒性。我们的假设是 乙醇会抑制信号通路， 细胞毒性，并激活促进线粒体通透性的途径 过渡这一理论得到了我们初步观察的支持， 乙醇抑制TNF α诱导的P13激酶依赖性BAD磷酸化 并以p38 MAPK依赖和caspase 8非依赖的方式促进细胞死亡。 方式此外，乙醇暴露使线粒体对MPT敏感， 导致外周苯二氮卓受体水平升高， MPT孔的推定组分。我们的具体目标是#1）进一步定义 乙醇在P13激酶活性改变中的作用及其影响 对TNF α细胞毒性的影响，以及#2）描述了 p38 MAPK在乙醇中的活化加上TNF α细胞毒性; #3）定义 TNF加乙醇引起MPT的机制。