PAD2 and CitH3 in Pathogenesis of Sepsis-induced ALI

项目总结摘要 脓毒症是一种威胁生命的器官功能障碍，由宿主对 感染和急性肺损伤(ALI)是与脓毒症相关的主要死亡原因。一个 中性粒细胞/巨噬细胞参与脓毒症致ALI的新机制 经历细胞死亡，释放核组蛋白和瓜氨酸组蛋白H3(CitH3)以引起 组织损伤，加重肺损伤。CitH3由氨基精氨酸催化 脱氨酶2和4(PAD2和PAD4)。我们发现慢性阻塞性肺疾病患者血清中CitH3水平升高。 败血症-ALI，但不是由于非感染性原因导致的ALI患者，提示CitH3可能是 一个生物标志物，也是脓毒症-ALI的潜在致病因素。显著的立面 脓毒症患者支气管肺泡灌洗液(BALF)中检测到CitH3和PAD2，而不是PAD4 病人。而与野生型相比，Pad4-/-小鼠没有表现出明显的败血症表型 产仔后，Pad2-/-小鼠对脓毒症-ALI和其他器官的抵抗力显著增强 功能障碍。Pad2-/-败血症小鼠存活率的提高与细菌的增强有关 由于巨噬细胞功能增强而清除。我们有数据表明这种化学物质 抑制PAD2和CitH3抗体隔离对脓毒症有治疗作用 老鼠身上的阿里。结合我们在细胞和分子生物学、动物模型和临床方面的专业知识 在脓毒症和化学生物学方面的研究，我们的团队研究旨在剖析 PAD2和CitH3在调节巨噬细胞功能中的生理作用 脓毒症(目标1)，并将PAD2和CitH3作为新的目标进行概念验证研究 小鼠脓毒症-ALI的治疗手段(目标2)。循环中的CitH3可以作为信号分子 并与膜受体(S)结合以实现其生物学功能；或者CitH3可以进入宿主 细胞通过内吞作用直接干扰其生存或死亡途径。因此，知识 在膜上，CitH3与巨噬细胞的相互作用将显著增加 脓毒症-ALI等多脏器的发病机制及可能的治疗 功能障碍。

PROJECT SUMMARY ABSTRACT Sepsis is a life-threatening organ dysfunction caused by dysregulated host response to infection, and acute lung injury (ALI) is a leading cause of death associated with sepsis. An emerging mechanism of sepsis induced-ALI (sepsis-ALI) involves neutrophils/macrophages undergoing cell death, releasing nuclear histones and citrullinated histone H3 (CitH3) to cause tissue damage and exacerbate pulmonary injury. CitH3 is catalyzed by peptidylarginine deiminase 2 and 4 (PAD2 and PAD4). We found that CitH3 is elevated in serum of patients with sepsis-ALI, but not in ALI patients due to non-infectious causes, suggesting that CitH3 could be a biomarker, as well as a potential causative factor for sepsis-ALI. Significant elevations of CitH3 and PAD2 in bronchoalveolar lavage fluid (BALF), not PAD4, are detected in septic patients. While Pad4-/- mice do not show a clear septic phenotype compared with wild type littermates, the Pad2-/- mice are strikingly more resistant to sepsis-ALI and other organ dysfunctions. The improved survival of the Pad2-/- septic mice is linked to enhanced bacterial clearance due to enhanced function of macrophages. We have data to show that chemical inhibition of PAD2 and antibody sequestration of CitH3 have therapeutic benefits to treat sepsis- ALI in mice. Combining our expertise in cell and molecular biology, animal models of and clinical research in sepsis, and chemical biology, our team-based research aims to dissect the physiological actions of PAD2 and CitH3 in modulating macrophage function associated with sepsis (Aim 1), and to conduct proof-of-concept studies targeting PAD2 and CitH3 as novel means to treat sepsis-ALI in mice (Aim 2). Circulating CitH3 could act as a signaling molecule and bind to membrane receptor(s) to fulfill its biological function; or CitH3 can enter the host cells via endocytosis to directly interfere with their survival or death pathways. Thus, knowledge on the membrane delimited interaction between CitH3 and macrophages will add significant insight into the pathogenesis and potential treatment of sepsis-ALI and other multi-organ dysfunctions.