Therapeutic Targeting of Myeloperoxidase in Acute Inflammation

描述（由申请方提供）：急性血管炎症中髓过氧化物酶的治疗靶向。多形核中性粒细胞（PMNs）被认为是急性炎症发作（如脓毒症和急性冠状动脉综合征）期间血管损伤的关键介质。髓过氧化物酶（MPO）是一种由中性粒细胞大量表达并在活化过程中分泌的血红素蛋白，具有强的促炎特性，并可能直接导致组织损伤。除了作为一氧化氮（NO）的催化“汇”，MPO还催化氧化、硝化和氯化反应，已知这些反应在炎症反应期间调节生理和病理事件。此外，最近的研究表明，MPO血清水平有力地预测了随后心血管事件的风险增加，并扩展了从传统生化标志物中获得的预后信息。此外，越来越多的证据支持MPO在人类血管NO信号转导受损中的因果作用，这一观点在MPO敲除小鼠中得到了很大程度的证实。生物化学、细胞和生理学数据支持这样的观点，即MPO的治疗性抑制将有利于减轻这种酶在急性炎症发作期间的损伤作用。然而，目前，科学家和临床医生还没有生物相容的策略来治疗MPO催化活性的抑制。因此，MPO的小分子抑制剂可以证明在急性炎症性血管疾病的治疗中是有用的。尽管以前已经鉴定出MPO抑制剂，但大多数具有固有毒性、非选择性生物学效应，或者没有足够的效力用作体内有效治疗剂。我们最近发现，取代苯基硫脲（PTU）衍生物是有效的MPO抑制剂在体外。基于上述前提和我们的初步数据，我们假设取代的硫脲可以通过抑制MPO的催化反应在急性炎症期间充当抗炎和血管保护剂。为了检验这一假设，将探讨以下具体目标：1）构建一系列合理设计的基于硫脲的MPO抑制剂，并阐明结构/活性关系，目的是设计具有适合治疗用途的物理性质和毒性特征的强效抑制剂，和2）定义基于硫脲的MPO抑制剂作为抗炎剂和血管保护剂的能力，并利用这些抑制剂阐明MPO在急性炎症发作期间通过生理学、基因组学和代谢组学方法导致全身损伤的机制。这些研究的成功完成将首次提供靶向MPO的小分子疗法，用于治疗急性血管炎症和损伤。此外，这些新型抑制剂的开发和使用将扩大可用于进一步确定MPO在炎症期间诱导血管损伤的机制的动物模型的库（其中基因敲除不可用），并评估其可被间接调节的程度。公共卫生相关性：项目叙述：中性粒细胞在急性炎症发作期间（如败血症和心肌梗死期间发生的炎症）对血管损伤起重要作用。髓过氧化物酶（MPO）是由中性粒细胞表达的高度丰富的血红素蛋白/酶，其产生既可损伤血管壁又可损害血管一氧化氮信号传导和生理学的反应性物质。尽管有这些知识，目前还没有抑制MPO的治疗策略。我们预计，我们的研究将导致开发新的MPO小分子抑制剂，可能被用作治疗急性血管炎性疾病的治疗剂，并将允许进一步阐明炎症期间MPO诱导血管损伤的机制。

DESCRIPTION (provided by applicant): Therapeutic Targeting of Myeloperoxidase in Acute Vascular Inflammation. Polymorphonuclear neutrophils (PMNs) are recognized as critical mediators of vascular injury during acute episodes of inflammation such as sepsis and acute coronary syndromes. Myeloperoxidase (MPO), a hemoprotein abundantly expressed by PMNs and secreted during activation, possesses potent proinflammatory properties and may contribute directly to tissue injury. In addition to serving as a catalytic `sink' for nitric oxide (NO), MPO also catalyzes oxidation, nitration, and chlorination reactions known to modulate physiological and pathological events during inflammatory responses. Additionally, recent studies have demonstrated that MPO serum levels powerfully predict an increased risk for subsequent cardiovascular events and extend the prognostic information gained from traditional biochemical markers. Moreover, a growing body of evidence now supports a causal role of MPO in compromised vascular NO signaling in humans, and this notion is largely confirmed in MPO knock-out mice. Biochemical, cellular, and physiological data support the notion that therapeutic inhibition of MPO would be beneficial for mitigating the injurious effects of this enzyme during acute inflammatory episodes. Currently, however, there are no biologically compatible strategies available to scientists and clinicians for therapeutic inhibition of the catalytic activities of MPO. Therefore, small-molecule inhibitors of MPO could prove useful in the treatment of acute inflammatory vascular diseases. Whereas inhibitors of MPO have been previously identified, most either possess inherent toxicity, nonselective biological effects, or are not of sufficient potency to be utilized as effective therapeutics in vivo. We have recently discovered that substituted phenylthiourea (PTU) derivatives are potent inhibitors of MPO in vitro. Based upon above premises, and our preliminary data, Based upon these premises, and our preliminary data, we hypothesize that substituted thioureas can serve as anti- inflammatory and vasoprotective agents during acute inflammation by inhibiting the catalytic reactions of MPO. To test this hypothesis, the following specific aims will be addressed: 1) To construct a rationally- designed series of thiourea-based inhibitors of MPO, and elucidate structure/activity relationships with the intention of designing powerful inhibitors with physical properties and toxicity profiles amenable to therapeutic use, and 2) To define the capacity of thiourea-based MPO inhibitors to serve as anti-inflammatory and vasoprotective agents, and to utilize these inhibitors to elucidate the mechanisms by which MPO contributes to systemic injury during acute episodes of inflammation using physiological, genomic and metabolomic approaches. Successful completion of these studies will provide, for the first time, small molecule therapeutics that target MPO for the treatment of acute vascular inflammation and injury. Additionally, the development and use of these novel inhibitors will expand the repertoire of animal models that can be utilized (where gene knockouts are not available) to further define the mechanisms by which MPO induces vascular injury during inflammation and assess the extent to which this can be modulated pharmacologically. PUBLIC HEALTH RELEVANCE: Project Narrative: Neutrophils play important contributing roles to vascular injury during acute episodes of inflammation such as that which occurs during sepsis and myocardial infarction. Myeloperoxidase (MPO) is a highly abundant hemoprotein/enzyme expressed by neutrophils that produces reactive species that can both damage the blood vessel wall and compromise vascular nitric oxide signaling and physiology. Despite this knowledge, no therapeutic strategies to inhibit MPO are currently available. We anticipate that our studies will lead to the development of novel small molecule inhibitors of MPO that could potentially be utilized as therapeutics for the treatment of acute vascular inflammatory diseases, and will allow for further elucidation of the mechanisms by which MPO induces vascular injury during inflammation.