Methylglyoxal-induced macrophage metabolic dysregulation in sepsis

脓毒症是一种对感染的异常免疫反应1， U.S.A.总体死亡率约为20 - 30%，在感染性休克的情况下增加至约40 - 50% 1 - 3。脓毒症是 特征为应激性高血糖4、线粒体功能障碍5和持续性强氧化 条件虽然脓毒症是一种涉及许多不同细胞和组织的复杂疾病， 了解巨噬细胞（Mf）在脓毒症中的作用可能揭示新的治疗靶点。MF展览 体外和体内动态的、刺激依赖的功能可塑性及其活动的关键变化 在脓毒症期间被认为是由细菌产物引发的（例如，脂多糖; LPS）和 促炎细胞因子（例如，干扰素-g; IFN-g）将Mf重编程为高度促炎性， 活化的"或" M1 "表型。在6.这些信号通路也稳定了转录因子低氧- 诱导因子-1a（HIF-1a）7，8. HIF-1a是糖酵解基因的主要调节因子9，促进了糖酵解基因的深刻变化。 "代谢开关"，"瓦尔堡效应"，10 - 12，在M1 Mf中，糖酵解占主导地位，线粒体 即使当存在氧时，氧化磷酸化也基本上不存在。我们认为这种代谢 在脓毒症期间，通过驱动促炎细胞因子的产生， 由于组织暴露于损伤性M1 MF依赖性活性氧（ROS）、蛋白酶和 生物活性脂质。虽然细胞因子和ROS已被广泛研究，但对细胞因子和ROS的作用知之甚少。 甲基乙二醛（MG），一种高度反应性的二羰基副产物，可以在细胞内积累， 磷酸丙糖异构酶（TPI）介导的糖酵解反应14，15。显著地， 败血性休克患者已被鉴定为与疾病严重程度相关的生物标志物21。我们有 报道，在体外用LPS和IFN-γ刺激时，MG在M1 Mf中积累，并导致 在体外和内毒素小鼠的肺中与宿主蛋白形成共价"MG-加合物" 17。我们 中心假设是MG，一种相对短寿命但高度反应性的代谢产物， LPS + IFN-g激活Mf，指导脓毒症中的炎性M1 Mf分化，以及抑制Mf分化的策略 MG的产生或活性将阻止这种分化，从而减少Mf导向的炎症。我们 科学前提是，可以利用MG积累的选择性靶向来减轻脓毒症- 相关的组织损伤和死亡。我们认为LPS + IFN-g诱导的HIF-1a稳定化启动了HIF-1a的表达， 脓毒症通过增加糖酵解、MG蓄积、MG介导的 破坏线粒体功能的线粒体蛋白的糖化。具体目标1将表征 Mf中MG积累破坏线粒体功能的机制，Aim 2将研究 代谢信号通路对MG积累的影响，Aim 3将测试MG的治疗功效。 降解酶以减轻内毒素和细菌败血症。

Sepsis is an aberrant immune response to infection1 with approximately one million cases/year in the U.S.A. and an overall fatality rate of ~20-30%, increasing to ~40-50% in the case of septic shock1-3. Sepsis is characterized by stress hyperglycemia4, mitochondrial dysfunction5, and persistent, strongly oxidizing conditions. Although sepsis is a complex disease involving many different cells and tissues, a better understanding of the role of macrophages (Mf) during sepsis may reveal new therapeutic targets. Mf exhibit dynamic, stimulus-dependent functional plasticity in vitro and in vivo and critical changes to their activities during sepsis are thought to be initiated by bacterial products (e.g., lipopolysaccharide; LPS) and proinflammatory cytokines (e.g., interferon-g; IFN-g) that reprogram Mf to a highly proinflammatory, “classically activated” or “M1” phenotyperev. in 6. These signaling pathways also stabilize the transcription factor Hypoxia- Inducing Factor-1a (HIF-1a)7,8. HIF-1a is a master regulator of glycolytic genes9, facilitating a profound “metabolic switch,” the “Warburg effect” rev. in 10-12, in M1 Mf in which glycolysis predominates and mitochondrial oxidative phosphorylation is essentially absent, even when oxygen is present. We propose that this metabolic dysregulation underlies inflammation during sepsis, by driving production of proinflammatory cytokines as well as exposure of tissues to damaging M1 Mf-dependent reactive oxygen species (ROS), proteases, and bioactive lipids. While cytokines and ROS have been extensively studied, less is known about the role of methylglyoxal (MG), a highly reactive, dicarbonyl byproduct that can accumulate intracellularly during the glycolytic reaction mediated by triose phosphate isomerase (TPI)14,15. Significantly, elevated MG in sera of septic shock patients has been identified as a biomarker that correlates with disease severity21. We have reported that MG accumulates in M1 Mf upon stimulation with LPS and IFN-g in vitro, and results in the formation of covalent “MG-adducts” with host proteins both in vitro and in the lungs of endotoxic mice17. Our central hypothesis is that MG, a relatively short-lived, but highly reactive metabolite generated in response to LPS+IFN-g activation of Mf, directs inflammatory M1 Mf differentiation in sepsis, and that strategies that inhibit MG production or activity will prevent such differentiation, and thereby reduce Mf-directed inflammation. Our scientific premise is that selective targeting of MG accumulation can be capitalized upon to mitigate sepsis- associated tissue damage and death. We propose that LPS + IFN-g-induced stabilization of HIF-1a initiates sepsis by promoting M1 Mf differentiation through increased glycolysis, MG accumulation, MG-mediated glycation of mitochondrial proteins that disrupts mitochondrial function. Specific Aim 1 will characterize mechanisms by which MG accumulation in Mf disrupts mitochondrial function, Aim 2 will examine the role of metabolic signaling pathways on MG accumulation, and Aim 3 will test the therapeutic efficacy of MG- degrading enzymes to mitigate endotoxicity and bacterial sepsis.