Immunometabolism in Sepsis

 描述(申请人提供)：脓毒症是一种临床全身炎症反应综合征，发生在感染或损伤后的患者，仍然是包括美国在内的世界各地重症监护病房的主要死亡原因。新的证据表明，免疫代谢可能通过调节细胞因子的表达和释放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是一种晚期致死性全身炎症介质，具有更广泛的临床干预治疗时间窗口。这些令人兴奋的发现提出了几个关于PKM2在脓毒症发病机制中的未知作用以及调节PKM2表达和HMGB1释放的新机制的重要问题。我们假设PKM2介导的免疫代谢是脓毒症的一个新的标志，它有助于细胞因子(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：目的1.明确脓毒症时免疫和非免疫细胞中PKM2表达和活性的调节机制。我们将验证AMPK是PKM2表达和活性的负调节因子的假设，从而在体外和体内抑制激活的巨噬细胞、单核细胞和内皮细胞的有氧糖酵解和HMGB1的释放。目的2.明确脓毒症时免疫细胞和非免疫细胞有氧糖酵解调节HMGB1释放的机制。我们将检验这一假设，即PKM2介导的有氧糖酵解产生的代谢物(例如乳酸)可以抑制包括SIRT1在内的组蛋白脱乙酰酶的活性，进而在体外和体内激活的巨噬细胞、单核细胞和内皮细胞中实现HMGB1的超乙酰化和随后释放。目的3.在两种实验动物模型上测定PKM2抑制对脓毒症的保护作用。我们将通过改变乳酸蓄积、HMGB1释放、炎症反应和器官功能障碍来检验这样一种假设：在髓系细胞中去除PKM2的小鼠可以免受致死性内毒素血症或盲肠结扎以及穿刺性多菌败血症的保护。这些激动人心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角色和HMGB1释放机制的理解，并指导未来治疗脓毒症和其他致命性炎症性疾病的治疗策略的发展。

 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.