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

镰状细胞病（SCD）是美国最流行的遗传性血液疾病， 每365名非洲裔美国人中有1人，每16，300名西班牙裔美国人中有1人。SCD与寿命缩短有关 预期和严重的身体和心理疾病，由于并发症引起的复发性 血管闭塞和溶血性贫血。血红蛋白衍生产物对TLR 4的激活是一个重要的免疫调节机制。 一种恶性炎症级联反应的组分，涉及内皮细胞活化、多细胞 血小板/中性粒细胞/红细胞聚集体和氧化应激。SCD对犬尿氨酸代谢的影响 特别是关于新的生物活性犬尿氨酸衍生代谢物的产生， 不被赏识本文发现的生物活性犬尿氨酸衍生的介体激活Nrf 2依赖性 抗氧化酶的表达，抑制NF-κB调节的炎症信号传导， NLRP 3炎性体活性。生物活性犬尿氨酸代谢物的形成在稳态下上调 在小鼠模型和人类SCD患者中，初步数据表明， 增加氯化血红素，血管闭塞危机（VOC）和器官损伤的关键介质。通过抑制NF-κB- 依赖性反应和下调NLRP 3炎性体，这种新的犬尿氨酸衍生化合物 具有作为能够调节内皮细胞的内源性抗炎介质的潜力， 血小板和免疫细胞活化以减弱VOC。此外，已知Nrf 2活化在哺乳动物中是保护性的。 SCD通过抑制促炎信号传导，上调血红素分解代谢酶HO-1， 增加内源性抗氧化防御，抑制活性物质。利用相关原电池 来自携带关键途径缺失的动物的培养系统，临床相关SCD转基因 小鼠模型、高特异性LC-MS/MS策略和最先进的定量荧光活体肺 显微镜下，研究计划将建立背后的抗炎作用的机制， 生物活性犬尿氨酸代谢物及其在体内减弱血管闭塞的潜力。本申请 建立在坚实的生物化学基础上，并应用关键的生物和分析工具， 从体外化学过渡到转化科学，最终目标是积极影响 人体健康从这项研究计划中获得的知识将对生成固体具有至关重要的意义。 R 01未来应用的初步目的是更好地定义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病症中， 其涉及慢性炎症、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.