Mitochondrial metabolism in microbial sepsis

项目摘要/摘要 脓毒症是重症监护病房最常见的死亡原因，是美国的主要负担 医疗保健系统。微生物感染和创伤是急性全身性疾病最常见的诱因 炎症反应，最终导致败血症的器官衰竭和死亡。线粒体，a 高度新陈代谢活跃的细胞器，已被证明在先天免疫功能中起着重要作用。 和炎症反应。线粒体代谢(有丝分裂代谢)的强劲变化发生在 临床和实验性败血症。然而，导致有丝分裂代谢改变的信号机制 而其在脓毒症发病机制中的作用还知之甚少。在这项提案中，我们的目标是 目的：研究线粒体钙信号介导的代谢异常对脑缺血再灌注损伤的影响。 微生物败血症时的先天免疫功能。我们的初步研究确定了线粒体钙 单一转运体(MCU)是线粒体钙摄取的关键钙通道，是细菌的重要调节因子 致死和败血症发炎。我们发现，MCU的遗传消融导致吞噬功能的改善 细菌杀灭和IL-1β(IL-1β)分泌减少，这是由于LC_3相关吞噬作用(LAP)增加所致。 从机制上讲，MCU通过促进线粒体代谢产物乙酰化来抑制LAP复合体的组装。 通过丙酮酸脱氢酶(PDH)产生辅酶A(乙酰辅酶A)。因此，封锁MCU或 PDH功能可能是治疗微生物败血症的一种有前景的治疗方案。的目标是 建议研究线粒体钙信号介导的有丝分裂的功能和机制。 吞噬体内细菌杀灭和炎症的代谢，这两者都是宿主的关键决定因素 微生物败血症期间的生存。我们假设：1)MCU缺乏症患者的乙酰辅酶A生成减少 巨噬细胞通过蛋白乙酰化依赖机制促进LAP的形成；2)增强LAP 形成促进吞噬小体成员修复机制以限制过度炎症小体介导的IL-1β 3)CPI-613对PDH的药理抑制作用在治疗微生物败血症中是有效的。 将采用盲肠结扎和穿刺术诱导的多菌败血症模型来检验其作用和 MCU介导的乙酰辅酶A代谢功能。我们将测试CPI-613对PDH的抑制是否起到 对脓毒症引起的死亡以及脓毒症引起的免疫抑制的保护作用。这些措施的结果 研究将为有丝分裂代谢的调节和功能提供新的见解，这可能会 从而在微生物败血症的治疗中找到新的治疗靶点。

Project Summary/Abstract Sepsis is the most common cause of death in intensive care units and represents a major burden to the US health care system. Microbial infection and trauma are the most common triggers of acute systemic inflammatory response that eventually leads to end organ failure and mortality in sepsis. Mitochondria, a highly metabolically active organelle, have been shown to play an essential role in the innate immune function and inflammatory response. Robust changes in mitochondrial metabolism (mito-metabolism) occur during clinical and experimental sepsis. However, the signaling mechanism leading to alterations in mito-metabolism and its functional consequence on the pathogenesis of sepsis are poorly understood. In this Proposal, we aim to study the detrimental effects of metabolic abnormalities mediated by mitochondrial calcium signaling on the innate immune function during microbial sepsis. Our preliminary studies identified the mitochondrial calcium uniporter (MCU), a key calcium channel for mitochondrial calcium uptake, as an essential regulator of bacterial killing and septic inflammation. We found that genetic ablation of MCU resulted in improved phagosomal bacterial killing and less interleukin 1β (IL-1β) secretion due to elevated LC3-associated phagocytosis (LAP). Mechanistically, MCU inhibits the assembly of LAP complex by promoting mitochondrial metabolite acetyl- coenzyme A (acetyl-CoA) generation via the pyruvate dehydrogenase (PDH). Therefore, blockade of MCU or PDH function may represent a promising therapeutic regimen for treating microbial sepsis. The goal of the proposal is to examine the function and mechanism of mitochondrial calcium signaling-mediated mito- metabolism on phagosomal bacterial killing and inflammation, both of which are key determinants of host survival during microbial sepsis. We hypothesize that 1) decreased acetyl-CoA generation in Mcu-deficient macrophages promotes LAP formation via protein acetylation-dependent mechanism; 2) enhanced LAP formation promotes phagosome member repair mechanism to limit excessive inflammasome-mediated IL-1β cleavage; 3) pharmacological inhibition of PDH by CPI-613 is effective in the treatment of microbial sepsis. Cecal ligation and puncture-induced polymicrobial sepsis model will be employed to examine the role and functions of MCU-mediated acetyl-CoA metabolism. We will test whether PDH inhibition by CPI-613 plays a protective effect on sepsis-induced mortality, as well as sepsis-induced immunosuppression. Results of these studies will provide novel insights into the regulation and function of mito-metabolism, which can potentially lead to the identification of new therapeutic targets in the treatment of microbial sepsis.