PPARgamma and PPARgamma agonists in septic shock

描述(申请人提供)：败血症是对感染的一种全身性反应，其特征是血液动力学和代谢紊乱，导致休克、多器官系统衰竭和死亡。老年患者的发病率和死亡率不成比例地增加，他们的治疗是一个主要的临床挑战。因此，研究与年龄相关的脓毒症易感性的分子机制是至关重要的。科学证据表明，线粒体功能和生物能量学的深刻变化在疾病过程中发挥了作用。功能障碍的线粒体的积累可能会进一步增加氧化应激和细胞死亡。在过去的资金周期中，我们已经证明，与年龄相关的脓毒症易感性与核激素受体、过氧化物体增殖物激活受体-？(PPAR？)、PPAR？和肝X受体？(LXR？)，众所周知的代谢和抗炎细胞反应的调节器。在新的初步研究中，我们观察到在脓毒症期间，与年轻动物(2-3月龄)相比，老年小鼠(11-12个月龄)的肝脏线粒体复合体I功能受损。在老年小鼠中，这一事件与自噬的标志LC3II的表达减少有关，自噬是使细胞能够处理有缺陷的线粒体的重要过程。我们还发现，老年小鼠肝脏中PPAR？？的核表达减少。辅活化子1-？线粒体生物发生的主要调节者PGC-1？)，以及关键的能量状态感受器AMP激活的蛋白激酶(AMPK)的激活减少。并负调控雷帕霉素复合体1(MTORC1)的哺乳动物靶标--自噬控制器。有趣的是，AMPK激活剂的治疗能够改善脓毒症老年小鼠的肝功能并提高早期存活率。因此，这些初步数据提出了一个新的假设，即与年龄相关的AMPK调节失调可能导致自噬和线粒体生物发生受损的恶性循环，从而增加对脓毒症的易感性，损害器官恢复。为了验证这一新概念，本文提出了三个具体目标。目的1研究多菌败血症小鼠从幼年到衰老过程中自噬和线粒体生物发生的变化及其与AMPK活性的关系。通过药理功能获得和遗传功能丧失的研究，在目标2中，我们将确定AMPK通过下游的mTORC1和PGC-1？调控自噬和线粒体生物发生的确切作用。小路。药理学研究还将确定AMPK激动剂是否可以减轻脓毒症引起的全身炎症反应、多器官衰竭和死亡。通过对幼年或老年小鼠原代肝细胞和心肌细胞的体外研究，我们将验证AMPK也影响PPAR？、PPAR？核功能的假设。和LXR？，这有助于自噬和线粒体生物发生的机制。这些研究可能会对开发新的治疗方法以降低脓毒症的发病率和死亡率产生影响。 公共卫生相关性：败血症是非心脏重症监护病房死亡的主要原因，据估计，美国每年有超过21.5万人死亡。与年轻患者相比，老年患者的预后较差。我们的项目旨在了解衰老和脓毒症期间调节器官功能修复能力的分子机制。我们将专注于自噬，这是一种允许细胞处置功能失调的细胞器的过程，以及线粒体生物发生，这是一种允许细胞恢复功能细胞器的过程。这些修复过程的贡献将在使用基因改变的小鼠的脓毒症实验模型中进行检验，以及针对一种特定蛋白的药物干预，AMP激活的蛋白被认为参与了这些过程的调节。

DESCRIPTION (provided by applicant): Sepsis is a systemic response to infection characterized by hemodynamic and metabolic derangements that result in shock, multiple organ system failure and death. The incidence and mortality is disproportionately increased in elderly patients, whose treatment represents a major clinical challenge. Thus, the investigation of the molecular mechanisms underlying the age-dependent susceptibility to sepsis is of utmost importance. Scientific evidence suggests that profound changes in mitochondrial function and bioenergetics play a role in the disease process. Accumulation of dysfunctional mitochondria may further increase oxidative stress and cell death. During the past funding cycle, we have demonstrated that the age-dependent susceptibility to sepsis is associated with a marked dysfunction of the nuclear hormone receptors, peroxisome proliferator-activated receptor-? (PPAR?), PPAR?, and liver X receptor-? (LXR?), well-known regulators of metabolic and anti- inflammatory cellular responses. In new preliminary studies, we have observed that mitochondrial complex I function is impaired in liver of old mice (11-12 months of age) when compared to young animals (2-3 months of age) during sepsis. This event in old mice is associated with reduced expression of LC3 II, a marker of autophagy, an important process that enables the cells to dispose defective mitochondria. We also have found that liver of old mice exhibits reduced nuclear expression of the PPAR? coactivator 1-? (PGC-1?), the master regulator of mitochondrial biogenesis, and reduced activation of AMP-activated protein kinase (AMPK), a crucial energy status sensor, which is known to activate PGC-1? and negatively regulate the autophagy controller, the mammalian target of rapamycin complex 1 (mTORC1). Interestingly, treatment with an AMPK activator was able to ameliorate liver function and improve early survival rate in septic old mice. Thus, these preliminary data raise the novel hypothesis that an age-related dysregulation of AMPK may lead to a vicious cycle of impaired autophagy and mitochondrial biogenesis, thus enhancing susceptibility to sepsis and impairing organ recovery. Three specific aims are proposed to validate this novel concept. In aim 1 we will investigate the changes of autophagy and mitochondrial biogenesis and their correlation with AMPK activation from infancy through senescence in polymicrobial sepsis in mice. With pharmacological gain-of-function and genetic loss-of-function studies, in aim 2 we will establish the precise role of AMPK in modulating autophagy and mitochondrial biogenesis through the downstream mTORC1 and PGC-1? pathways. Pharmacological studies will also establish whether AMPK activators mitigate sepsis-induced systemic inflammatory response, multiple organ failure and death. With in vitro studies in primary hepatocytes and myocytes from young or old mice, in aim 3 we will test the hypothesis that AMPK also affects the nuclear function of PPAR?, PPAR? and LXR?, which then contribute to the mechanisms of autophagy and mitochondrial biogenesis. These studies may have an impact in developing novel therapies to decrease sepsis morbidity and mortality. PUBLIC HEALTH RELEVANCE: Sepsis is the leading cause of mortality in non-cardiac intensive care units with estimates of over 215,000 deaths in the United States each year. Elderly patients have poor outcomes when compared with young patients. Our project is aimed to understand the molecular mechanisms that regulate the reparative capacity of organ function during aging and sepsis. We will focus on autophagy, a process that allows the cell to dispose dysfunctional organelles, and mitochondria biogenesis, a process that allows the cell to restore functional organelles. The contribution of these reparative processes will be examined in an experimental model of sepsis using genetically altered mice as well as drug interventions directed at a specific protein, the AMP activated kinase, which is thought to be involved in the regulation of these processes.