Peroxidase-Based Toxicity In Hypereosinophilic States.'

嗜酸性粒细胞增多状态下基于过氧化物酶的毒性。

• 批准号: 6755168
• 负责人: ARNE SLUNGAARD
• 金额: $ 36.93万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-06-01 至 2007-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6755168
• 关键词: apoptosis; biomarker; cardiotoxin; cyanogen bromide; endocardium; enzyme activity; eosinophil; eosinophilia; gene expression; gene targeting; genetically modified animals; heart disorder; histopathology; inflammation; interleukin 5; laboratory mouse; mass spectrometry; myocardium; necrosis; nitrites; oxidative stress; oxidizing agents; pathologic process; peroxidases; thiocyanates; thromboplastin; tissue /cell culture

DESCRIPTION (provided by applicant): Eosinophi1 (EO) phagocytes destroy parasites but can also damage host tissue. Although allergies are the most common example of EO-mediated pathology, the hypereosinophilic Syndrome (HES) is the most striking. HES is a systemic hematologic disorder characterized by multi-organ system involvement, preeminently a characteristic, usually lethal form of heart disease. Eosinophilic heart disease (EHD occurs in a variety of hypereosinophilic states, irrespective of their cause. Endocardial and myocardial deposition of EO specific granule proteins, of which eosinophil peroxidase (EPO) is the most abundant, is proposed to mediate cardiotoxicity in EHD. Despite the abundance of EPO and the vigor of the EO respiratory burst, little is known about the contribution of EPO-mediated oxidative damage to the pathology of eosinophilic inflammatory states. We find that three unusual substrates - bromide (Br-), nitrite (NO2-), and thiocyanate (SCN-) - compete for oxidation by EPO in physiologic fluids in the presence of H202, yielding, respectively, HOBr, NO2., and HOSCN. The relative toxicity of these oxidants for human cells is HOBr> NO2>> HOSCN; yet EPO preferentially oxidizes SCN > NO2 - > Br-. We hypothesize that SCN "buffers" against generation by EPO of the more cytotoxic N02- and Br- based oxidants and consequently serum SCN- levels, which are dietarily determined, may modulate EPO toxicity. The overall goal of our proposed work is to examine the hypothesis that that EPO-generated oxidants impose damage in a substrate-determined manner to mammalian cells and tissue that contributes to the pathogenesis of EHD, which we propose as a paradigm for any organ damage occurring in eosinophil inflammatory states. The first specific aim is to test the hypothesis that whereas HOBr and N02 cause necrotic cell death by reacting with membrane components to destroy membrane integrity, HOSCN imposes sulfhydryl-targeted intracellular oxidative stress that can influence tissue factor gene expression and induce apoptosis. The second specific Aim is to test the hypothesis that an interleukin-5 (IL.5) transgenic mouse line will develop progressive functional, anatomic, and histologic manifestations of EHD with a parallel accumulation of EPO-specific protein oxidative damage as assessed by newly developed sensitive, substrate-specific amino acid "biomarkers." The third specific aim is to test the hypothesis that EPO contributes to the pathogenesis of EHD in the IL.5 transgenic mouse line. We will compare EHD severity, longevity, and EPO biomarker levels in the IL-5 transgenic line with that of an IL-S transgenics crossbred with an EPO 'knockout" line. The fourth specific aim is test the hypothesis that increasing serum SCN- inhibits, and decreasing SCN- promotes, EPO-mediated protein oxidant damage and the severity of EHD in IL-5 transgenic mice. These studies, if successful, will establish a murine model for HES and EHD, prove a mole for EPO-mediated oxidant damage in the pathogenesis of EHD, and suggest a simple strategy fur its treatment, (i.e., dietary supplementation with inexpensive SCN-), that could be applied even in impoverished communities as well as against more common allergic diseases, such as asthma.

描述（由申请人提供）：嗜酸性粒细胞1 （EO）吞噬细胞破坏寄生虫，但也会损害宿主组织。虽然过敏是eo介导的病理中最常见的例子，但嗜酸性粒细胞过多综合征（HES）是最引人注目的。HES是一种以多器官系统受累为特征的全身性血液系统疾病，是一种特征性的、通常致命的心脏病。嗜酸性心脏疾病（EHD）发生在各种嗜酸性亢进状态下，与病因无关。心内膜和心肌沉积EO特异性颗粒蛋白，其中嗜酸性过氧化物酶（EPO）含量最多，被认为介导EHD的心脏毒性。尽管EPO有丰富的含量和EO呼吸爆发的活力，但EPO介导的氧化损伤对嗜酸性炎症状态的病理作用知之甚少。我们发现三种不寻常的底物-溴化物（Br-），亚硝酸盐（NO2-）和硫氰酸盐(SCN-) -在H202存在的生理液体中竞争EPO的氧化，分别产生HOBr和NO2。和HOSCN。这些氧化剂对人体细胞的相对毒性为HOBr> NO2>> HOSCN；然而EPO优先氧化SCN > NO2 - > Br-。我们假设SCN“缓冲”EPO产生的更具细胞毒性的N02和Br基氧化剂，因此血清SCN水平（由饮食决定）可能调节EPO的毒性。我们提出的工作的总体目标是检验epo产生的氧化剂以一种底物决定的方式对哺乳动物细胞和组织造成损害的假设，这有助于EHD的发病机制，我们提出这是在嗜酸性粒细胞炎症状态下发生的任何器官损伤的范例。第一个具体目的是验证HOBr和N02通过与膜组分反应破坏膜完整性导致坏死细胞死亡的假设，而HOSCN施加巯基靶向的细胞内氧化应激，可以影响组织因子基因表达并诱导细胞凋亡。第二个特定目的是测试假设，白细胞介素5 （IL.5）转基因小鼠系将发展出EHD的进行性功能，解剖和组织学表现，并通过新开发的敏感的，底物特异性氨基酸“生物标志物”评估epo特异性蛋白质氧化损伤的平行积累。第三个具体目的是在IL.5转基因小鼠系中验证EPO参与EHD发病机制的假设。我们将比较IL-5转基因系与IL-S转基因系与EPO“敲除”系杂交的EHD严重程度、寿命和EPO生物标志物水平。第四个具体目的是验证IL-5转基因小鼠血清SCN-升高抑制epo介导的蛋白氧化损伤和EHD严重程度，而SCN-降低促进epo介导的EHD的假设。这些研究如果成功，将建立HES和EHD的小鼠模型，证明EHD发病机制中epo介导的氧化损伤的存在，并提出一种简单的治疗策略（即，在饮食中补充廉价的SCN-），这种策略甚至可以应用于贫困社区，也可以用于治疗更常见的过敏性疾病，如哮喘。