Neutrophils and Hepatotoxicity

描述（由申请人提供）：中度炎症增强药物肝毒性反应的能力（例如，雷尼替丁）和其它异生素试剂的特征已经在几种动物模型中得到了表征。一个共同的发现是，中性粒细胞（PMN）和止血与随后的组织缺氧是关键的球员在炎症增强肝毒性。激活的中性粒细胞通过释放毒性蛋白酶如弹性蛋白酶和组织蛋白酶G杀死肝实质细胞（HPC）。最近，我们发现，PMN弹性蛋白酶对HPC的杀伤作用在缺氧条件下被加速和加强。该提案的目标是测试缺氧和中性粒细胞蛋白酶在药物-炎症相互作用期间相互作用导致HPC损伤的假设，并开始了解这种相互作用的分子基础。缺氧对体外PMN蛋白酶杀死HPC的发展和剂量反应性的影响以及这种相互作用在体内药物-炎症模型中的重要性将被确定。由于缺氧诱导因子-1 α（HIF-1 α）可以启动细胞死亡信号，并在体内药物-炎症相互作用期间肝毒性发作前表达，我们将描述其在体外缺氧/PMN蛋白酶相互作用期间和体内药物-炎症相互作用期间HPC杀伤中的作用。最后，由于中性粒细胞蛋白酶破坏蛋白质二硫键异构酶（PDI），细胞保护性缺氧应激蛋白在HPC膜，弹性蛋白酶/缺氧介导的HPC死亡的PDI失活的作用将进行探讨。在这些研究中将采用药理学、反义寡核苷酸、条件性无效和基因过表达方法，以提供炎症条件期间可能发生的缺氧环境增强细胞毒性PMN蛋白酶损伤HPC的能力的机制的知识。这些结果将有助于了解炎症组织损伤一般和炎症如何作为一个敏感因素的毒性，由于药物和其他外源性制剂。公共卫生相关性：药物毒性和许多肝脏疾病涉及白色血细胞，例如在缺氧组织环境中操作的嗜中性粒细胞，从而引起肝损伤。了解中性粒细胞如何与缺氧相互作用以促进肝损伤，可能会导致更好的方法来预防或治疗药物不良反应和其他类型的炎性肝损伤。

DESCRIPTION (provided by applicant): The capacity of modest inflammation to potentiate hepatotoxic responses to drugs (e.g., ranitidine) and other xenobiotic agents has been characterized in several animal models. A common finding is that both neutrophils (PMNs) and hemostasis with consequent tissue hypoxia are critical players in inflammation- potentiated hepatotoxicity. Activated PMNs kill hepatic parenchymal cells (HPCs) through the release of toxic proteases such as elastase and cathepsin G. Recently, we found that the killing of HPCs by PMN elastase is accelerated and potentiated by hypoxia. The goals of the proposal are to test the hypothesis that hypoxia and PMN proteases interact to cause HPC injury during drug-inflammation interaction and to begin to understand the molecular basis for this interaction. The influence of hypoxia on the development and dose-responsiveness of HPC killing by PMN proteases in vitro and the importance of this interaction in a drug-inflammation model in vivo will be determined. Since hypoxia-inducible factor-1 alpha (HIF-1 alpha) can initiate cell death signaling and is expressed before the onset of hepatotoxicity during drug-inflammation interaction in vivo, we will delineate its role in HPC killing during hypoxia/PMN protease interaction in vitro and during drug-inflammation interaction in vivo. Finally, since PMN proteases destroy protein disulfide isomerase (PDI), a cytoprotective hypoxic stress protein in HPC membranes, the role of PDI inactivation in elastase/hypoxia-mediated HPC death will be explored. Pharmacological, antisense oligonucleotide, conditional null and gene overexpression approaches will be employed in these studies to provide knowledge of mechanisms by which a hypoxic environment likely to occur during inflammatory conditions enhances the capacity of cytotoxic PMN proteases to damage HPCs. The results will contribute to understanding inflammatory tissue injury generally and how inflammation acts as a susceptibility factor for toxicity due to drugs and other xenobiotic agents. Public Health Relevance: Drug toxicity and many liver diseases involve white blood cells such as neutrophils operating in an oxygen-deficient tissue environment to cause liver injury. Understanding how neutrophils interact with oxygen deficiency to promote liver injury could lead to better ways to prevent or treat adverse drug reactions and other types of inflammatory liver injury.