NF-kappa B in Murine Sepsis

小鼠脓毒症中的 NF-kappa B

• 批准号: 7332172
• 负责人: Peter Q Eichacker
• 金额: --
• 依托单位: CLINICAL CENTER
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7332172
• 关键词: NF; kappa; Murine; Sepsis

Despite the use of effective antibiotics in combination with cardiopulmonary support, the mortality rate from sepsis and septic shock for the last three decades has remained high (29%). Furthermore, the incidence of sepsis and septic shock appear to be increasing. New therapeutic approaches with wide clinical applicability are needed to lower the high mortality rate of this syndrome. Excessive release of inflammatory mediators contributes directly to the pathogenesis of organ injury and death occurring during severe infection complicated by sepsis and septic shock. Nuclear factor kappa B (NF-KB) is a nuclear transcription regulatory protein central to the activation of several different genes encoding proteins associated with the inflammatory response during sepsis. Under normal conditions, NF-KB remains sequestered in an inactive state in the cytoplasm under the control of its cytoplasmic inhibitor (I-(B) proteins. However, differing kinds of stimuli including LPS (the toxic moiety of gram-negative bacteria) and cytokines (e.g. TNF alpha and interleukin-6) cause the phosphorylation, ubiquitinylation, and the subsequent degradation of I-KB proteins in turn resulting in the activation of NF-KB. Then the DNA-binding subunits of NF-KB migrate into the nucleus and activate expression of target genes that code for proteins in the inflammatory and immune responses, such as chemokines, cytokines, inducible nitric oxide synthase (iNOS), and adhesion molecules. Many of these gene products have been closely associated with the pathogenesis of the hemodynamic instability and organ injury occurring during sepsis and septic shock. Therefore, agents designed to inhibit NF-KB may have broad antiinflammmatory effects that could be beneficial during sepsis. However, many of the host mediators associated with the inflammatory response and under the control of NF-KB also contribute to innate immunity and the clearance of bacterial infection. Suppression of NF-KB during sepsis could therefore also worsen underlying infection. The present protocol has tested the effects of of modulating NF-KB in an LPS challenged mouse sepsis model. Initial studies investigated the effects of parthenolide, a sesquiterpene lactone derived from Asteraceae plants. Parthenolide had been reported to inhibit NF-KB and improve survival when administered up to 3 hours following intravenous LPS stimulation in mice or rats challenged with intraperitoneal or intravenous LPS respectively. However in investigations that have thus far been completed, parthenolide worsened survival with LPS challenge in our mouse model. Furthermore, the effects of parthenolide on NF-KB were time dependent, decreasing these levels early but increasing them later. Similar changes were noted with plasma cytokine levels. We have now extended these studies investigating ethyl pyruvate, a second agent which has been reported to inhibit NF-KB and the inflammatory response and to improve survival in sepsis models including ones employing LPS challenge. Consistent with our findings with parthenolide however, ethyl pyruvate has also been harmful in our most recent studies, and has had similar time dependent effects on inflammatory cytokine and chemokine release. Tissue NF-KB and stress kinase measurements are ongoing in this study. Overall however, these studies suggest that the effects of NF-KB inhibition in animal models of sepsis may be variable. Understanding the effects of inhibiting such a central mediator in the inflammatory and host responses during sepsis must be well defined before this is explored in patients.

尽管使用有效的抗生素并结合心肺支持，但过去三十年脓毒症和脓毒性休克的死亡率仍然很高（29%）。此外，败血症和败血性休克的发病率似乎正在增加。需要具有广泛临床适用性的新治疗方法来降低该综合征的高死亡率。 炎症介质的过度释放直接导致严重感染并发脓毒症和感染性休克时器官损伤和死亡的发病机制。核因子 kappa B (NF-KB) 是一种核转录调节蛋白，对于激活编码与败血症期间炎症反应相关的蛋白质的几种不同基因至关重要。在正常情况下，NF-KB 在其细胞质抑制剂 (I-(B) 蛋白的控制下，以非活性状态隔离在细胞质中。然而，包括 LPS（革兰氏阴性菌的毒性部分）和细胞因子（例如 TNF α 和白细胞介素 6）在内的不同种类的刺激会导致磷酸化， I-KB 蛋白的泛素化和随后的降解进而导致 NF-KB 的激活。然后，NF-KB 的 DNA 结合亚基迁移到细胞核中，激活编码炎症和免疫反应中蛋白质的靶基因的表达，例如趋化因子、细胞因子、诱导型一氧化氮合酶 (iNOS) 和 粘附分子。许多这些基因产物与脓毒症和脓毒性休克期间发生的血流动力学不稳定和器官损伤的发病机制密切相关。因此，旨在抑制 NF-KB 的药物可能具有广泛的抗炎作用，这在败血症期间可能是有益的。然而，许多与炎症反应相关并在 NF-KB 控制下的宿主介质也有助于先天免疫和 清除细菌感染。因此，败血症期间抑制 NF-KB 也可能使潜在感染恶化。 本方案测试了在 LPS 攻击的小鼠脓毒症模型中调节 NF-KB 的效果。初步研究调查了小白菊内酯（一种源自菊科植物的倍半萜内酯）的作用。据报道，在分别接受腹膜内或静脉内 LPS 攻击的小鼠或大鼠静脉内 LPS 刺激后长达 3 小时内，小白菊内酯可抑制 NF-KB 并提高存活率。然而，在迄今为止已完成的研究中，小白菊内酯在我们的小鼠模型中因LPS攻击而使生存恶化。此外，小白菊内酯对 NF-KB 的影响具有时间依赖性，早期会降低这些水平，但随后会增加。血浆细胞因子水平也出现类似的变化。 我们现在扩展了这些研究，调查丙酮酸乙酯，据报道，丙酮酸乙酯是第二种药物，可抑制 NF-KB 和炎症反应，并提高脓毒症模型（包括采用 LPS 攻击的模型）的生存率。然而，与我们对小白菊内酯的研究结果一致，丙酮酸乙酯在我们最近的研究中也是有害的，并且对炎症细胞因子和趋化因子的释放具有类似的时间依赖性影响。本研究正在进行组织 NF-KB 和应激激酶测量。 然而，总体而言，这些研究表明 NF-KB 抑制在脓毒症动物模型中的作用可能是可变的。在对患者进行探索之前，必须明确了解抑制脓毒症期间炎症和宿主反应中这种中心介质的影响。