Role of Protein Ubiquitination in Sepsis

项目摘要 脓毒症及其并发症是当代医学的一个重大挑战。大约25万例 脓毒症每年在美国导致死亡，为医疗保健系统带来巨大的成本。取决于 根据医疗标准，全世界败血症患者的死亡率为30%至70%， 总死亡率约为50%。NLRP3是大分子信号复合物的关键成分， 炎性小体促进caspase 1依赖性IL-1 β促炎细胞因子的产生， 在败血症的发展过程中虽然导致NLRP 3炎性小体激活的因素已经被证实是 广泛研究了负调节NLRP3炎性体活化的机制， 因此控制脓毒症是未知的。我们发现NLRP 3被Cbl-b的泛素化所抑制，Cbl-b是一种E3 泛素连接酶这一发现的重要性可以通过观察到脂多糖 (LPS)注射或盲肠结扎穿孔（CLP）诱导Cblb-/-小鼠的显著死亡率， 野生型（WT）对照，并且这种由LPS诱导的Cblb-/-小鼠中的死亡率增加被IL-1抑制剂阻断。 受体拮抗剂或引入NLRP 3缺陷。因此，我们的核心假设是在败血症期间， Cbl-b是自泛素化/活化的并泛素化NLRP 3，其反过来抑制NLRP 3并减弱NLRP 3的表达。 NLRP3介导的先天反应。我们建议确定1）Cbl-b如何调节NLRP 3炎性小体 2）Cbl-b是否以及如何使用CLP诱导的NLRP 3炎性小体在体内控制非典型NLRP 3炎性小体; 脓毒症和LPS诱导的脓毒性休克作为研究模型。了解Cbl-b在调节 NLRP3炎性体介导的信号通路将提供新的见解和治疗策略， 对抗败血症

Project Summary Sepsis with its complications is a major challenge in contemporary medicine. Approximately 250,000 cases of sepsis lead to fatalities in the USA annually at huge costs for the healthcare system. Depending on the standards of medical care, the worldwide mortality rates in septic humans range from 30% to 70% with an aggregate mortality rate of ~50%. NLRP3 is a key component of the macromolecular signaling complex called the inflammasome that promotes caspase 1-dependent production of IL-1β pro-inflammatory cytokine involved in the development of sepsis. Although the factors leading to NLRP3 inflammasome activation have been extensively studied, the mechanisms for negatively regulating the activation of the NLRP3 inflammasome, and thus, controlling sepsis, are not known. We found that NLRP3 is inhibited by ubiquitination by Cbl-b, an E3 ubiquitin ligase. The significance of this finding is demonstrated by the observation that that lipopolysaccharide (LPS) injection or cecal ligation and puncture (CLP) induces a significant mortality in Cblb-/- mice compared to wild-type (WT) controls, and this increased mortality in Cblb-/- mice induced by LPS is blocked by an IL-1 receptor antagonist or by introducing NLRP3 deficiency. Therefore, our central hypothesis is that during sepsis, Cbl-b is autoubiquitinated/activated and ubiquitinates NLRP3, which in turn inhibits NLRP3 and attenuates NLRP3-mediated innate responses. We propose to determine 1) how Cbl-b regulates NLRP3 inflammasome activation; 2) whether and how Cbl-b controls non-canonical NLRP3 inflammasome in vivo using CLP-induced sepsis and LPS-induced septic shock as the study models. Understanding the role of Cbl-b in regulating the NLRP3 inflammasome-mediated signaling pathway will provide novel insights and therapeutic strategies to combat sepsis.