PAD2 and CitH3 in Pathogenesis of Sepsis-induced ALI

项目摘要 脓毒症是一种危及生命的器官功能障碍，由宿主对 感染和急性肺损伤（ALI）是与脓毒症相关的死亡的主要原因。一个 脓毒症诱导的ALI（脓毒症-ALI）的新机制涉及中性粒细胞/巨噬细胞 经历细胞死亡，释放核组蛋白和瓜氨酸化组蛋白H3（CitH 3）， 组织损伤并加重肺损伤。CitH 3由肽基精氨酸催化 脱亚胺酶2和4（PAD 2和PAD 4）。我们发现CitH 3在患有糖尿病的患者血清中升高， 脓毒症-ALI，但不是在非感染性原因的ALI患者，这表明CitH 3可能是 是脓毒症-ALI的生物标志物，也是潜在的致病因素。显著升高 支气管肺泡灌洗液（BALF）中检测到CitH 3和PAD 2，而不是PAD 4， 患者虽然与野生型相比，Pad 4-/-小鼠没有显示出明确的脓毒症表型， 与同窝出生的小鼠相比，Pad 2-/-小鼠对脓毒症-ALI和其他器官损伤的抵抗力明显更强。 功能障碍Pad 2-/-脓毒症小鼠存活率的提高与细菌感染的增强有关。 由于巨噬细胞功能增强而清除。我们有数据表明， PAD 2抑制和CitH 3的抗体螯合对治疗脓毒症具有治疗益处- 小鼠ALI。结合我们在细胞和分子生物学、动物模型和临床 在败血症和化学生物学的研究，我们的团队为基础的研究旨在剖析 PAD 2和CitH 3在调节巨噬细胞功能中的生理作用 脓毒症（目标1），并进行针对PAD 2和CitH 3的概念验证研究， 治疗小鼠败血症-ALI的方法（目的2）。循环CitH 3可以作为信号分子 并与膜受体结合以实现其生物学功能;或者CitH 3可以进入宿主 细胞通过内吞作用直接干扰其存活或死亡途径。因此， 在CitH 3和巨噬细胞之间的膜界定的相互作用将显著增加 深入了解脓毒症-ALI和其他多器官损伤的发病机制和潜在治疗 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.