Prevention of Apoptotic Cell Death in Sepsis by BCL-2

描述(由申请人提供)： 败血症是大多数重症监护病房的主要死亡原因，在美国，每年有超过21万人死于压倒性感染(或由此导致的多器官衰竭)。最近的一项流行病学研究估计，每年有75万人患上脓毒症，花费167亿美元。研究表明，细胞凋亡是脓毒症细胞死亡的重要机制，预防细胞凋亡可提高脓毒症动物模型的存活率。细胞凋亡可通过受体途径或线粒体途径进行。在受到特定凋亡刺激的特定类型的细胞中，这两条途径可以连接在一起，使两条途径在同一细胞中发挥作用。了解脓毒症中细胞凋亡死亡的机制是至关重要的，因为这一知识可能揭示刺激因素，并使针对相关通路的有效治疗成为可能。目前，在脓毒症中起作用的特殊的细胞凋亡途径，即受体和线粒体，仍存在争议，而且这两条途径都被报道被激活。我们实验室的初步发现表明，这两条途径可能在脓毒症诱导的淋巴细胞凋亡中起作用，尽管它们似乎发生在解剖上不同的脾区域，与对不同淋巴细胞表型的影响一致。和Bcl2一样，丝氨酸苏氨酸激酶Akt是一种癌蛋白，可以防止细胞因各种凋亡刺激而死亡。Akt的确切作用机制尚不清楚，但在某些情况下，它的作用机制似乎与Bcl2不同。我们实验室的初步发现表明，在T细胞中过度表达Akt的小鼠淋巴细胞不会发生脓毒症诱导的凋亡，并且与非转基因小鼠相比，小鼠的存活率有所提高。这一建议的指导假设是：1)脓毒症时淋巴细胞的凋亡通过受体和线粒体两种途径进行；2)Akt在T细胞中的过度表达可以阻止淋巴细胞的凋亡，提高脓毒症的存活率。研究将使用临床相关的脓毒症动物模型进行。此外，还将对患有和不患有脓毒症的危重患者的血液进行翻译研究。注意，初步研究结果显示，与重症非脓毒症患者相比，脓毒症患者的淋巴细胞凋亡增加。这一建议将提供有关脓毒症中淋巴细胞凋亡性死亡机制的重要新信息，并最终可能导致对这种高度致命的疾病进行更有效的治疗。

DESCRIPTION (provided by applicant): Sepsis is the leading cause of death in most intensive care units with over 210,000 people succumbing to overwhelming infection (or the resultant multiple organ failure) in the United States annually. A recent epidemiologic study estimated that 750,000 people develop sepsis annually at a cost of $16.7 billion dollars. Studies show that apoptosis is an important mechanism of cell death in sepsis and that prevention of apoptosis can improve survival in animal models of sepsis. Apoptosis can proceed by either a receptor or mitochondrial mediated pathway. In certain types of cells subjected to particular apoptotic stimuli, the two pathways can be linked such that both pathways are operative in the same cell. Understanding the mechanisms of apoptotic cell death in sepsis is vital because this knowledge may reveal the inciting stimuli and enable an effective therapy aimed at the responsible pathway. Currently, the particular apoptotic pathway operative in sepsis, i.e., receptor versus mitochondrial, is debated and both pathways have been reported to be activated. Preliminary findings in our laboratory indicate that both pathways may be operative in sepsis-induced lymphocyte apoptosis although they appear to be occurring in anatomically different regions of the spleen, consistent with effects on different lymphocyte phenotypes. Like Bcl-2, the serine threonine kinase Akt is an oncoprotein which prevents cell death due to a variety of apoptotic stimuli. The exact mechanism of action of Akt is unknown but in some instances it appears to work by a mechanism that is distinct from that of Bcl-2. Preliminary findings in our laboratory show that lymphocytes from mice that over express Akt in T cells do not undergo sepsis-induced apoptosis and the mice have improved survival compared to non-transgenic. The guiding hypotheses of this proposal are: I) lymphocyte apoptosis in sepsis proceeds via both receptor and mitochondrial mediated pathways and, ii) over-expression of Akt in T cells will prevent lymphocyte apoptosis and improve sepsis survival. Studies will be conducted using a clinically relevant animal model of sepsis. In addition, translational studies will be conducted in blood from critically ill patients with and without sepsis. Note that preliminary findings demonstrate increased lymphocyte apoptosis in patients with sepsis versus critically ill non-septic patients. This proposal will provide important new information regarding mechanisms of apoptotic lymphocyte death in sepsis and may ultimately lead to a more effective therapy for this highly lethal disorder.