Altered innate leukocyte programming dynamics in sepsis

项目摘要 败血症造成严重的健康问题，没有有效的预防或治疗。关键的绊脚石是 先天性白细胞稳态被破坏的高度复杂性质。脓毒症单核细胞稳态破坏 反映在炎症过程的早期急剧上升，随后是后期代偿性 宽容脓毒症患者中性粒细胞稳态的破坏主要表现为"游走性麻痹" 其中败血性中性粒细胞失去了向细菌产物迁移的潜力， 无菌组织，由于优先减少FPR 2和诱导CCR 5。脓毒性中性粒细胞也有 减少产生中性粒细胞胞外陷阱（NET）的可能性。总的来说，这些被破坏的先天 白细胞稳态可能损害宿主防御并加剧多器官炎症。然而，在这方面， 单核细胞引发和中性粒细胞麻痹的潜在机制知之甚少。由于其高度 动态性质，目前的体外实验系统或体内动物模型不能正确地捕获 破坏了白细胞的稳态PI过去的系统分析与实验和计算 方法揭示了一种模型系统，该模型系统在体外和体内重现了被破坏的人类白细胞稳态。 体内应用亚临床超低剂量脂多糖（LPS）。与广泛的影响形成鲜明对比， 使用更高剂量的LPS，优先促进单核细胞耐受，Li博士的实验室记录了超级- 低剂量的LPS "引发"单核细胞长时间的"失控"炎症。此外，李实验室观察到，超- 低剂量LPS将嗜中性粒细胞"编程"为麻痹状态，模拟FPR2降低的脓毒症嗜中性粒细胞， 降低的细菌杀灭潜力和升高的CCR5。单核细胞启动和中性粒细胞麻痹 在离体人血白细胞中可以观察到低剂量LPS。盲肠结扎穿孔脓毒症 模型，Li实验室证明了用超低剂量LPS预处理的小鼠中败血症死亡率加剧。 从机制上讲，Li实验室观察到超低剂量LPS通过以下方式有效地重编程单核细胞和中性粒细胞： 破坏关键的自我平衡事件和分子。基于这些有趣的观察， 是为了了解先天免疫动力学的破坏，负责发病率和死亡率的升高， 败血症作为至关重要的第一步，我们的主要目标是更好地了解负责 破坏单核细胞和中性粒细胞的稳态。该项目计划测试中心假设， 脓毒症期间单核细胞启动和中性粒细胞麻痹是由关键的稳态平衡破坏引起的， 分子和过程。目的1将检验这样的假设，即稳态分子的破坏， RelB负责单核细胞引发，这有助于增加脓毒症死亡率。目标2将揭示 导致中性粒细胞麻痹的基本细胞和分子机制。Aim 3将测试 白细胞动力学的改变可能会加剧，而白细胞稳态的恢复可能会减弱 脓毒症发病机制

PROJECT SUMMARY Sepsis poses grave health concerns with no effective prevention or cure. The key stumbling block is the highly complex nature of the disrupted innate leukocyte homeostasis. Disrupted sepsis monocyte homeostasis is reflected in a dramatic early upswing of inflammatory processes followed by a late-phase compensatory tolerance. Disrupted neutrophil homeostasis in sepsis patients is cardinally represented by “migratory paralysis” in which septic neutrophils lose migratory potential toward bacterial products while retaining migration toward sterile tissues, due to preferential reduction of FPR2 and induction of CCR5. Septic neutrophils also have reduced potential for generating neutrophil extra-cellular trap (NET). Collectively, these disrupted innate leukocyte homeostasis may compromise host defense and exacerbate multi-organ inflammation. However, mechanisms underlying monocyte priming and neutrophil paralysis are poorly understood. Due to their highly dynamic natures, current experimental systems in vitro or animal models in vivo fail to properly capture the disrupted leukocyte homeostasis. The PI’s past systems analyses with experimental and computational approaches reveal a model system that recapitulates the disrupted human leukocyte homeostasis in vitro and in vivo by applying subclinical super-low dose lipopolysaccharide (LPS). In sharp contrast to the effects of widely used higher dosages LPS which preferentially facilitate monocyte tolerance, Dr. Li’s lab documented that super- low dose LPS “primes” monocytes for prolonged “run-away” inflammation. In addition, Li lab observed that super- low dose LPS “programs” neutrophils into a paralytic state, mimicking septic neutrophils with reduced FPR2, reduced potential of bacterial killing and elevated CCR5. Monocyte priming and neutrophil paralysis by super- low dose LPS can be observed in human blood leukocyte ex vivo. With the cecal ligation and puncture sepsis model, Li lab demonstrated exacerbated sepsis mortality in mice pre-conditioned with super-low dose LPS. Mechanistically, Li lab observed that super-low dose LPS potently reprograms monocytes and neutrophils by disrupting key homeostatic events and molecules. Based on these intriguing observations, the long-term goal is to understand the disrupted innate immune dynamics responsible for the elevated morbidity and mortality of sepsis. As a crucial first step, our key objective is to better understand the mechanisms responsible for the disrupted homeostasis in monocytes and neutrophils. This project plans to test the central hypothesis that monocyte priming and neutrophil paralysis during sepsis are caused by the disruption of key homeostatic molecules and processes. Aim 1 will test the hypothesis that the disruption of homeostatic molecules such as RelB is responsible for the monocyte priming conducive for increased sepsis mortality. Aim 2 will reveal the fundamental cellular and molecular mechanisms responsible for neutrophil paralysis. Aim 3 will test whether that alteration of leukocyte dynamics may exacerbate, while restoration of leukocyte homeostasis may attenuate sepsis pathogenesis.