Resistance of Beta 2 Microglobulin Null Mice to Sepsis

描述(由申请人提供)： β2微球蛋白基因敲除小鼠缺乏CD8 T细胞和自然杀伤T细胞。与野生型小鼠相比，β2微球蛋白基因敲除小鼠在盲肠结扎和穿孔(CLP)引起的脓毒症中表现出更高的存活率。通过注射抗asialoGM1进一步耗尽自然杀伤细胞，使其几乎完全抵抗CLP诱导的死亡。这些观察结果背后的机制尚不清楚。然而，有两种潜在的机制具有很高的可能性。首先，CD8T、自然杀伤T和自然杀伤细胞可以通过放大促炎细胞因子和趋化因子的产生而影响先天免疫反应。在炎症过程中，这些细胞群也会造成直接的细胞损伤。因此，假设CD8T、自然杀伤T细胞和自然杀伤细胞通过放大促炎反应和/或导致直接的细胞损伤来促进或直接介导脓毒症所致的死亡。其次，β2微球蛋白由I类主要组织相容性复合体的β链和非经典的抗原提呈分子CD1组成。这两个分子分别对自身和外源抗原的呈递都很重要，但它们在脓毒症过程中调节炎症反应的作用尚不清楚。进一步推测，I类主要组织相容性复合体、CD1和/或未被识别的β2微球蛋白相关分子在脓毒症的免疫反应中起调节作用。本研究项目旨在验证这些假说。目的1：探讨CD8T、自然杀伤T细胞、自然杀伤细胞、I类主要组织相容性复合体和CD1在致死性腹内脓毒症发病机制中的作用。在CLP后，将测量对照组小鼠和缺乏这些细胞群和抗原呈递分子的小鼠的死亡率、细菌计数、器官损伤、心血管功能和酸碱平衡。特异性目的2：探讨CD8 T、自然杀伤T细胞和自然杀伤细胞、I类主要组织相容性复合体和CD1在致死性腹内脓毒症中调节促炎反应中的作用。CLP后，将测量对照组小鼠和CD8 T、自然杀伤T和自然杀伤细胞、I类主要组织相容性复合体和CD1缺乏的小鼠的腹内和全身细胞因子和趋化因子的产生。具体目的3：确定细胞溶解机制在致死性腹内脓毒症发病机制中的作用。我们将评估穿孔素、颗粒酶、Fas和FasL在CLP后CD8 T、自然杀伤T和自然杀伤细胞缺陷小鼠中的表达。穿孔素/颗粒酶和Fas-FasL通路的功能作用将通过评估穿孔素缺陷和FasL缺陷小鼠的存活率、心血管功能、器官损伤和酸碱平衡来确定。这些研究旨在确定在感染性休克发病机制中重要的新机制，最终目标是为这一致命疾病过程开发新的治疗方法。

DESCRIPTION (provided by applicant): Beta2 microglobulin knockout mice are deficient in CD8+ T cells and natural killer T cells. Compared to wild type mice, beta2 microglobulin knockout mice exhibit improved survival during sepsis caused by cecal ligation and puncture (CLP). Further depletion of natural killer cells by injection of anti-asialoGM1 confers near complete resistance to CLP-induced mortality. The mechanisms underlying these observations are unknown. However, two potential mechanisms have high probability. Firstly, CD8+ T, natural killer T and natural killer cells can impact innate immune responses by amplifying production of pro-inflammatory cytokines and chemokines. These cell populations can also cause direct cellular injury during inflammation. Therefore, it is hypothesized that CD8+ T, natural killer T and natural killer cells facilitate or directly mediate sepsis-induced mortality by amplifying the pro-inflammatory response and/or causing direct cellular injury. Secondly, beta2 microgiobulin comprises the beta chain of the class I major histocompatibility complex and the non-classical antigen-presenting molecule CD1. Both of these molecules are important for presentation of self and foreign antigens, respectively, but their roles in regulating inflammatory responses during sepsis are unknown. It is further hypothesized that the class I major histocompatibility complex, CD1 and/or unrecognized beta2 microglobulin-associated molecules play a role in modulating the immune response during sepsis. This research project is designed to test these hypotheses. The following specific aims are proposed: Aim 1: To determine the specific contributions of CD8+ T, natural killer T and natural killer cells, the class I major histocompatibility complex and CD1 to the pathogenesis of lethal intra-abdominal sepsis. Mortality, bacterial counts, organ injury, cardiovascular function and acid-base balance will be measured following CLP in control mice and mice that are deficient in these cell populations and antigen-presenting molecules. Specific Aim 2: To determine the functional roles of CD8+ T, natural killer T and natural killer cells, the class I major histocompatibility complex and CD1 in regulating the pro-inflammatory response during lethal intra-abdominal sepsis. Intra-abdominal and systemic cytokine and chemokine production will be measured following CLP in control mice and mice that are deficient in CD8+ T, natural killer T and natural killer cells, the class I major histocompatibility complex and CD1. Specific Aim 3: To determine the role of cytolytic mechanisms in the pathogenesis of lethal intra-abdominal sepsis. We will evaluate expression of perforin, granzymes, Fas and FasL in control mice and mice that are deficient in CD8+ T, natural killer T and natural killer cells after CLP. The functional roles of the perforin/granzyme and Fas-FasL pathways will be determined by assessing survival, cardiovascular function, organ injury and acid-base balance in perforin-deficient and FasL-deficient mice. These studies are designed to define new mechanisms that are important in the pathogenesis of septic shock with the ultimate goal of developing new treatments for this lethal disease process.