Peroxidase-Based Toxicity In Hypereosinophilic States.'

描述（由申请方提供）：嗜酸性粒细胞1（EO）吞噬细胞可破坏寄生虫，但也可损伤宿主组织。虽然过敏是EO介导的病理学最常见的例子，但嗜酸性粒细胞增多综合征（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病，是典型的、通常致命的心脏病。嗜酸性粒细胞性心脏病（EHD）发生在各种嗜酸性粒细胞过多的状态，无论其原因。EHD中，EO特异性颗粒蛋白（其中嗜酸性粒细胞过氧化物酶（EPO）最丰富）的内皮细胞和心肌沉积被认为介导了EHD的心脏毒性。尽管EPO的丰度和EO呼吸爆发的活力，但对EPO介导的氧化损伤对嗜酸性粒细胞炎症状态的病理学的贡献知之甚少。我们发现三种不寻常的底物-溴离子（Br-）、亚硝酸根（NO2-）和硫氰酸根（SCN-）-在H2 O2存在下在生理液体中竞争EPO的氧化，分别产生HOBr、NO2、和HOSCN。这些氧化剂对人体细胞的相对毒性为HOBr> NO2>> HOSCN;而EPO优先氧化SCN > NO2 - > Br-。我们假设SCN“缓冲剂”对抗EPO产生更多的细胞毒性的基于NO2和Br的氧化剂，并因此调节饮食确定的血清SCN-水平，可以调节EPO毒性.我们所提出的工作的总体目标是检查这一假设，即EPO产生的氧化剂以底物决定的方式对哺乳动物细胞和组织造成损伤，这有助于EHD的发病机制，我们提出作为嗜酸性粒细胞炎症状态中发生的任何器官损伤的范例。第一个具体目的是检验以下假设：HOBr和NO2通过与膜组分反应以破坏膜完整性而引起坏死性细胞死亡，HOSCN施加巯基靶向的细胞内氧化应激，其可以影响组织因子基因表达并诱导细胞凋亡。第二个具体目的是检验白细胞介素-5（IL.5）转基因小鼠系将发展EHD的进行性功能、解剖学和组织学表现，并伴有EPO特异性蛋白氧化损伤的平行积累（通过新开发的敏感、底物特异性氨基酸生物标志物进行评估）的假设。“第三个具体目标是检验EPO在IL. 5转基因小鼠系中参与EHD发病机制的假设。我们将比较IL-5转基因系与EPO“敲除”系杂交的IL-5转基因系的EHD严重程度、寿命和EPO生物标志物水平。第四个具体目的是测试增加血清SCN-抑制和减少SCN-促进EPO介导的蛋白氧化损伤和IL-5转基因小鼠中EHD的严重性的假设。这些研究如果成功，将建立HES和EHD的小鼠模型，证明EPO介导的氧化损伤在EHD发病机制中的作用，并提出一种简单的治疗策略（即，膳食补充剂与廉价的SCN-），这可以应用于甚至在贫困社区，以及对更常见的过敏性疾病，如哮喘。

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.