Anti-inflammatory actions of a novel hemin-induced electrophile in Sickle Cell Disease

镰状细胞病(SCD)是美国最常见的遗传性血液疾病，据估计 每365名非洲裔美国人中有1名，每16,300名西班牙裔美国人中有1名。SCD与寿命缩短有关 因复发引起的并发症而导致的预期和严重的身体和心理疾病 输精管闭塞和溶血性贫血。血红蛋白衍生产物对TLR4的激活是一个中心 恶性炎症级联反应的组成部分，涉及内皮细胞激活、多细胞形成 血小板/中性粒细胞/红细胞聚集与氧化应激。SCD对犬尿氨酸代谢的影响 特别是关于产生一种新的生物活性犬尿氨酸衍生代谢物的研究到目前为止都是 不被赏识。本文中发现的生物活性犬尿氨酸衍生介体激活Nrf2依赖 抗氧化酶的表达及抑制核因子-κB调节的炎症信号转导 NLRP3炎症体活性。生物活性犬尿氨酸代谢物的形成在稳定状态下上调 在小鼠模型和人类SCD患者中，初步数据表明，这种水平进一步 增加了氯化血红素，这是血管闭塞危象(VOC)和器官损伤的关键介质。通过抑制核因子-κB- 犬尿氨酸衍生化合物对NLRP3炎症体的依赖反应和下调作用 具有作为内源性抗炎介质的潜力，能够调节内皮细胞， 激活血小板和免疫细胞，以减轻VOC。此外，已知Nrf2的激活在 通过抑制促炎信号，上调血红素分解酶HO-1，以及通过 增强清除活性物质的内源性抗氧化剂防御。通过利用相关的主小区 一种临床相关的SCD转基因动物来源的培养系统 小鼠模型、高度特异的LC-MS/MS策略和最新的活体肺内定量荧光 显微镜下，这项研究计划将建立抗炎作用背后的机制 犬尿氨酸的生物活性代谢物及其在体内减轻血管闭塞的潜力。本申请是 建立在坚实的生化基础上，并应用关键的生物学和分析工具成功地 从体外化学到转化科学的过渡，最终目标是积极影响 人类健康。从这项研究计划中获得的知识对于生成固体将是至关重要的 为未来R01的应用作初步准备，旨在更好地确定犬尿氨酸的病理生理作用- 在SCD以及其他血液学和非血液学疾病中衍生的生物活性代谢物 其中涉及慢性炎症、氧化应激和缺血性器官损伤。

Sickle Cell Disease (SCD) is the most prevalent genetic blood disorder in the US affecting an estimated 1 in 365 African Americans and 1 in 16,300 Hispanic Americans. SCD is associated with decreased life expectancy and significant physical and psychological morbidity due to complications arising from recurrent vaso-occlusion and hemolytic anemia. The activation of TLR4 by hemoglobin-derived products is a central component of a pernicious inflammatory cascade that involves endothelial activation, formation of multicellular platelet/neutrophil/erythrocyte aggregates and oxidative stress. The effects of SCD on kynurenine metabolism and in particular, on the generation of a novel bioactive kynurenine-derived metabolite were hitherto unappreciated. The bioactive kynurenine-derived mediator discovered herein activates Nrf2-dependent expression of antioxidant enzymes and inhibits NF-κB regulated inflammatory signaling as well as abrogates NLRP3 inflammasome activity. Formation of the bioactive kynurenine metabolite is upregulated in steady state in both mouse models and human SCD patients, and preliminary data suggests that levels are further increased by hemin, a critical mediator of vaso-occlusive crises (VOC) and organ injury. By inhibiting NF-κB- dependent responses and downregulating the NLRP3 inflammasome, this novel kynurenine-derived compound has the potential to act as an endogenous anti-inflammatory mediator capable of regulating endothelial, platelet and immune cell activation to attenuate VOC. Furthermore, Nrf2 activation is known to be protective in SCD via inhibition of pro-inflammatory signaling, upregulation of the heme-catabolizing enzyme HO-1, and by increasing endogenous antioxidant defenses that scavenge reactive species. By utilizing relevant primary cell culture systems derived from animals bearing key pathway deletions, a clinically relevant SCD transgenic mouse model, highly specific LC-MS/MS strategies and state-of-the-art quantitative fluorescence intravital lung microscopy, the research plan will establish the mechanisms behind the anti-inflammatory actions of the bioactive kynurenine metabolite and its potential to attenuate vaso-occlusion in vivo. The present application is built on solid biochemical foundations, and applies critical biological and analytical tools to successfully transition from in vitro chemistry to translational science with the ultimate objective of positively impacting human health. The knowledge gained from this research plan will be of pivotal importance for generating solid preliminary for future R01 applications aimed at better defining the pathophysiological role of the kynurenine- derived bioactive metabolite in SCD as well as in other hematological and non-hematological conditions in which chronic inflammation, oxidative stress and ischemic organ injury are involved.