Immunometabolism in Sepsis

 描述（由申请人提供）：脓毒症是一种在感染或受伤后患者中发生的临床全身炎症反应综合征，仍然是包括美国在内的全世界重症监护病房死亡的主要原因。新的证据表明，免疫代谢可能通过其调节细胞因子的表达和释放的能力在脓毒症的发病机制中发挥重要作用。特别是，我们最近提供了第一个直接证据，证明 PKM2 介导的有氧糖酵解促进 HMGB1 的释放，HMGB1 是致命性全身炎症的晚期介质，具有更宽的临床干预治疗时间窗。这些令人兴奋的发现提出了一些重要问题，涉及 PKM2 在脓毒症发病机制中以前未知的作用，以及调节 PKM2 表达和 HMGB1 释放的新机制。我们假设 PKM2 介导的免疫代谢是脓毒症的一个新标志，有助于细胞因子（例如 HMGB1）的释放和随后的全身炎症反应。我们提出以下具体目标： 目标 1. 明确败血症期间免疫和非免疫细胞中 PKM2 表达和活性调节的潜在机制。我们将测试以下假设：AMPK 是 PKM2 表达和活性的负调节因子，因此在体外和体内抑制激活的巨噬细胞、单核细胞和内皮细胞中的有氧糖酵解和 HMGB1 释放。目标 2. 明确败血症期间免疫细胞和非免疫细胞中通过有氧糖酵解调节 HMGB1 释放的机制。我们将测试以下假设：PKM2 介导的有氧糖酵解产生的代谢物（例如乳酸）可以抑制组蛋白脱乙酰酶（包括 SIRT1）的活性，从而使 HMGB1 过度乙酰化并随后在体外和体内激活的巨噬细胞、单核细胞和内皮细胞中释放。目标 3. 确定 PKM2 抑制在两种实验动物模型中预防败血症的功效。我们将检验这样的假设：通过改变乳酸积累、HMGB1 释放、炎症反应和器官功能障碍，骨髓细胞中 PKM2 消融的小鼠可以免受致命性内毒素血症或盲肠结扎和穿刺诱发的多种微生物败血症的影响。这些令人兴奋的研究的完成将进一步提高我们对免疫代谢在炎症中的新作用以及 HMGB1 释放机制的理解，并指导未来治疗脓毒症和其他致命炎症性疾病的治疗策略的开发。

 DESCRIPTION (provided by applicant): Sepsis, a clinical systemic inflammatory response syndrome occurring in patients following infection or injury, remains the leading cause of death in intensive care units worldwide, including the United States. Emerging evidence indicates that immunometabolism may play an important role in the pathogenesis of sepsis through its ability to regulate the expression and release of cytokines. In particular, we recently provided the first direct evidence that PKM2-mediated aerobic glycolysis promotes the release of HMGB1, a late mediator of lethal systemic inflammation with a wider therapeutic time window for clinical intervention. These exciting findings raise several important questions regarding the previously unknown role of PKM2 in the pathogenesis of sepsis, as well as the novel mechanisms underlying the regulation of PKM2 expression and HMGB1 release. We hypothesize that PKM2-mediated immunometabolism is an emerging hallmark of sepsis that contributes to cytokine (e.g., HMGB1) release and the subsequent systemic inflammatory response. We propose the following specific aims: Aim 1. Define the mechanism underlying the regulation of PKM2 expression and activity in both immune and non-immune cells during sepsis. We will test the hypothesis that AMPK is a negative regulator of PKM2 expression and activity, and therefore suppresses aerobic glycolysis and HMGB1 release in activated macrophages, monocytes, and endothelial cells in vitro and in vivo. Aim 2. Define the mechanism underlying the regulation of HMGB1 release by aerobic glycolysis in both immune and non-immune cells during sepsis. We will test the hypothesis that metabolites production (e.g., lactate) from PKM2-mediated aerobic glycolysis can inhibit the activity of histone deacetylases including SIRT1, which in turn enables HMGB1 hyperacetylation and subsequent release in activated macrophages, monocytes, and endothelial cells in vitro and in vivo. Aim 3. Determine the efficacy of PKM2 inhibition in protecting against sepsis in two experimental animal models. We will test the hypothesis that mice with PKM2 ablation in myeloid cells are protected from lethal endotoxemia or cecal ligation and puncture-induced polymicrobial sepsis through altering lactate accumulation, HMGB1 release, inflammatory response, and organ dysfunction. The completion of these exciting studies will further improve our understanding of the emerging role of immunometabolism in inflammation and the mechanisms of HMGB1 release and guide future development of therapeutic strategies to treat sepsis and other lethal inflammatory diseases.