Autocrine regulation of neutrophil chemotaxis

 描述(申请人提供)：在重症监护和创伤患者中，中性粒细胞(PMN)趋化功能失调导致败血症和多器官衰竭。其潜在的机制只被部分了解，这是寻找有效的治疗干预措施以改善脓毒症和重症监护患者治疗的主要障碍。趋化性是一个复杂的过程，它使PMN能够定位和消除入侵的细菌。功能失调的趋化性不仅会损害宿主的防御，还会导致附带的宿主组织损伤。我们以前的工作已经证明，PMN的趋化需要自分泌的嘌呤能信号机制，包括细胞前沿局部释放ATP的机制，以及涉及细胞前后不同嘌呤能受体亚型的复杂的Pull-Push机制。最近我们发现，线粒体ATP形成的快速激活触发了这些嘌呤能信号机制。此外，我们还发现脓毒症伴随着全身性ATP的释放，干扰了PMN的自分泌嘌呤能导航系统。基于这一证据，我们假设支持线粒体ATP产生或消除全身性ATP干扰效应的治疗策略将改善PMN的趋化性和宿主防御，基于这些概念的临床策略迟早可能减少重症监护、脓毒症和创伤患者的发病率和死亡率。具体目的1.调节中性粒细胞趋化的机制：我们将研究调节三磷酸腺苷的产生的机制，三磷酸腺苷是细胞前后自分泌嘌呤能信号的燃料。将特别强调mTOR和AMPK及其在调节线粒体功能中的作用。特定目的2.患者中性粒细胞趋化性受损：我们将研究氧和葡萄糖供应以及系统的三磷酸腺苷如何影响中性粒细胞的趋化性，并探讨这些因素在重症监护患者中中性粒细胞趋化性受损中的作用。具体地说，我们将测试这些变量如何影响ICU患者的线粒体功能和PMN趋化性。具体目的3.恢复PMN趋化和宿主防御的治疗策略：最后，我们将使用小鼠脓毒症模型来测试改善PMN趋化和宿主防御的新治疗策略。我们将专注于提高线粒体ATP产量和减少系统ATP水平在其他功能反应中对PMN趋化的破坏性影响的方法。我们预计，我们的发现将促进对PMN趋化性调节机制的科学知识，这些知识将揭示新的治疗策略，最终可能导致改善创伤、脓毒症和危重患者的护理。

 DESCRIPTION (provided by applicant): In critical care and trauma patients, dysregulated neutrophil (PMN) chemotaxis contributes to sepsis and multi-organ failure. The underlying mechanisms are only partially understood, which is a major hurdle in the search for effective therapeutic interventions that improve the treatment of sepsis and critical care patients. Chemotaxis is a complex process that allows PMNs to locate and eliminate invading bacteria. Dysfunctional chemotaxis impairs not only host defense but can also contribute to collateral host tissue damage. Our previous work has demonstrated that PMN chemotaxis requires autocrine purinergic signaling mechanisms that involve localized release of cellular ATP at the leading edge and complex pull-push mechanisms that involve different purinergic receptor subtypes at the front and back of cells. Recently we found that rapid activation of mitochondrial ATP formation triggers these purinergic signaling mechanisms. In addition, we found that sepsis is accompanied by the release of systemic ATP, which interferes with the autocrine purinergic navigation systems of PMNs. Based on this evidence, we hypothesize that therapeutic strategies that support mitochondrial ATP production or eliminate the interfering effects of systemic ATP will improve PMN chemotaxis and host defense and that clinical strategies based on these concepts may sooner or later diminish morbidity and mortality in critically care, sepsis, and trauma patients. Specific Aim 1. Mechanisms that regulate PMN chemotaxis: We will study the mechanisms that regulate the production of ATP which fuels autocrine purinergic signaling at the front and back of cells. Special emphasis will be placed on mTOR and AMPK and their roles in regulating mitochondrial function. Specific Aim 2. Impaired PMN chemotaxis in patients: We will study how oxygen and glucose supply and systemic ATP affect PMN chemotaxis and we will investigate how these factors contribute to impaired PMN chemotaxis in critically care patients. Specifically, we will test how these variables affect mitochondrial function and PMN chemotaxis in ICU patients. Specific Aim 3. Therapeutic strategies to restore PMN chemotaxis and host defense: Finally, we will use a mouse sepsis model to test novel therapeutic strategies to improve PMN chemotaxis and host defenses. We will focus on approaches that improve mitochondrial ATP production and reduce the disruptive influence of systemic ATP levels on PMN chemotaxis in other functional responses. We anticipate that our findings will advance scientific knowledge of the mechanisms by which PMN chemotaxis is regulated and that this knowledge will reveal novel therapeutic strategies that may ultimately lead to improvements in the care of trauma, sepsis, and critical patients.