Neutrophils and Hepatotoxicity

描述（由申请人提供）：适度炎症增强药物（如雷尼替丁）和其他外源性药物的肝毒性反应的能力已在几种动物模型中得到表征。一个共同的发现是，中性粒细胞（pmn）和止血导致的组织缺氧是炎症增强肝毒性的关键参与者。活化的PMN通过释放有毒蛋白酶如弹性蛋白酶和组织蛋白酶g来杀死肝实质细胞（HPCs）。最近，我们发现PMN弹性蛋白酶对HPCs的杀伤在缺氧的情况下会被加速和增强。该提案的目的是验证缺氧和PMN蛋白酶在药物-炎症相互作用中相互作用导致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蛋白酶杀伤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-炎症相互作用期间的肝毒性发作之前表达，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-炎症相互作用期间在HPC杀伤中的作用。最后，由于PMN蛋白酶破坏HPC膜中的细胞保护性低氧应激蛋白二硫异构酶（PDI）， PDI失活在弹性酶/缺氧介导的HPC死亡中的作用将被探讨。这些研究将采用药理学、反义寡核苷酸、条件无效和基因过表达方法，以提供炎症条件下可能发生的缺氧环境增强细胞毒性PMN蛋白酶损伤HPCs的能力的机制。这些结果将有助于理解炎症组织损伤，以及炎症如何作为药物和其他外源性药物引起的毒性的易感性因素。公共卫生相关性：药物毒性和许多肝脏疾病涉及白细胞，如中性粒细胞在缺氧的组织环境中运作，导致肝损伤。了解中性粒细胞如何与缺氧相互作用以促进肝损伤，可以找到更好的方法来预防或治疗药物不良反应和其他类型的炎症性肝损伤。

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.