Elucidating the Role of Inherited Complement System Defects in the Molecular Pathophysiology of Sepsis and Purpura Fulminans

项目摘要 暴发性紫癜（PF）是一种罕见但破坏性的脓毒症并发症，患者 发生高度血栓性的弥散性血管内凝血（DIC）亚型，导致 肢解器官损伤和死亡PF可由一系列细菌引起， 感染，并通过极高水平的循环细胞因子和关键的失败来区分。 引起促凝血组织因子显著上调的抗炎途径 (TF)通过活化的单核细胞表达。因为PF代表了一种极端的疾病表型， 利用我们在这种疾病中的发现， DIC。然而，目前几乎没有什么是已知的分子病理生理学和 遗传易感性潜在的PF。利用生殖系全外显子组测序（WES）和 有针对性的基因发现方法，我们发现了一个显着富集罕见的，有害的， 与未选择的患者相比，PF患者的补体系统编码变体 脓毒症组（P<0.0001）。有趣的是，我们还发现这些变异可能与 尽管没有明显的PF，但脓毒症患者的死亡率增加。 假设补体系统缺陷导致全身炎症增加， 促凝血活性，导致凝血病的发展。在本项目的目标1中，我们 我将通过对临床上注释良好的患者进行WES来跟进我们的初步结果。 NHLBI BioLINCC储存库中来自无明显PF的脓毒症患者的标本。我们将 补体突变状态与血栓形成和炎症的血浆生物标志物相关 在调整年龄、性别、种族和合并症后， 系统缺陷与脓毒症中血栓炎症恶化有关。在目标2中，我们将 功能性表征补体受体3中一类新型罕见PF相关变体 和4（CR 3/4）对单核细胞驱动的炎症和血栓形成的影响。 这项工作将为研究先天性免疫缺陷和免疫缺陷之间的关系提供重要的新见解。 免疫和凝血失调，并生成基础WES数据集， 研究败血症中广泛存在的凝血障碍问题的生物学相关性。

PROJECT SUMMARY Purpura fulminans (PF) is a rare but devastating complication of sepsis in which patients develop a highly thrombotic subtype of disseminated intravascular coagulation (DIC), leading to dismemberment, end organ damage, and death. PF can be triggered by a range of bacterial infections and is distinguished by extremely high levels of circulating cytokines and failure of key anti-inflammatory pathways which cause a marked upregulation of procoagulant tissue factor (TF) expression by activated monocytes. Because PF represents an extreme disease phenotype, leveraging our findings in this disorder could yield key insights into the broader problem of septic DIC. However, at present almost nothing is known about the molecular pathophysiology and genetic predisposition underlying PF. Utilizing germline whole exome sequencing (WES) and a targeted gene discovery approach, we have found a significant enrichment in rare, deleterious coding variants in the complement systems of patients with PF compared to unselected patients with sepsis (P<0.0001). Intriguingly, we also found that these variants may be associated with increased mortality in unselected sepsis patients despite the absence of overt PF. We hypothesize that complement system defects lead to heightened systemic inflammation and procoagulant activity, resulting in the development of coagulopathy. In Aim 1 of this project, we will follow up on our preliminary results by performing WES on clinically well-annotated specimens in the NHLBI BioLINCC repository from septic patients without overt PF. We will correlate complement mutational status to plasma biomarkers of thrombosis and inflammation after adjusting for age, sex, ethnicity, and comorbidities in order to understand if complement system defects are associated with worsened thrombo-inflammation in sepsis. In Aim 2, we will functionally characterize a novel class of rare PF-associated variants in complement receptors 3 and 4 (CR3/4) with respect to their impact on monocyte-driven inflammation and thrombosis. The proposed work will provide important new insights into the relationship between innate immunity and dysregulated coagulation and generate a foundational WES dataset with biological correlates for studying the widespread problem of coagulopathy in sepsis.