Resistance of Beta 2 Microglobulin Null Mice to Sepsis

描述(申请人提供)：我们已经令人信服地表明，自然杀伤(NK)细胞促进盲肠结扎和穿孔(CLP)引起的脓毒症的发病。然而，脓毒症时NK细胞介导的促炎活性的机制尚不清楚。我们最近的研究表明，在CLP诱导的脓毒症过程中，大量的CXCR3+NK细胞离开脾进入腹膜腔。CXCR3配体CXCL9和CXCL10在脓毒症期间浓度较高，CXCR3缺陷小鼠对CLP诱导的生理功能障碍具有抵抗力。基于这些观察，我们假设CXCR3信号对NK细胞的募集和激活至关重要，并且CXCR3的作用在脓毒症的发病机制中起重要作用。以下具体目标将检验这些假设。目的1：探讨CXCR3在NK细胞迁移和活化中的作用及其在CLP脓毒症发病机制中的作用。CXCR3和激活标志物的表达将在原发感染部位和远处组织的NK细胞上进行评估。进一步的研究将评估CXCR3缺陷小鼠的NK细胞募集和激活情况，以及用中和抗体阻断CXCR3后的情况。我们还将确定CXCR3在亚致死性脓毒症、败血症所致多器官功能障碍和感染性休克发病机制中的重要性。明确CXCR3配体(CXCL9和CXCL10)在NK细胞募集和激活中的作用及其在CLP脓毒症发病机制中的作用。将检查主要感染部位和远程组织中CXCR3配体的细胞来源。将在CXCR3配体缺陷小鼠中或在使用中和抗体阻断CXCR3配体后研究NK细胞的迁移和激活。采用亚致死性脓毒症、败血症诱导的多器官功能障碍和感染性休克模型，研究CXCR3配体缺陷小鼠的生理功能、器官损伤和全身炎症反应。我们还将确定CXCR3配体在对照组小鼠或亚致死性脓毒症小鼠中直接诱导脓毒症综合征的能力。具体目的3.CLP诱导的脓毒症中调节CXCR3轴的因素的评估。这些研究将探讨脓毒症时NK细胞对CXCR3配体产生的贡献以及调节NK细胞CXCR3表达的因素。虽然脂多糖诱导的巨噬细胞产生CXCL10受TRIF依赖的信号调节，需要产生IFN2，但我们认为NK细胞通过产生IFN3来促进MyD88依赖的CXCL10的产生。在这项申请中提出了解决这一断言的研究。进一步的研究将评估旁分泌和自分泌机制对NK细胞CXCR3激活的重要性，以及调节NK细胞表达CXCR3的因素。 公共卫生相关性：我们已经令人信服地表明，自然杀伤(NK)细胞促进了败血症的发病。已知趋化因子受体CXCR3在某些疾病模型中调节NK细胞的功能。根据我们最近的研究，我们假设CXCR3信号对脓毒症时NK细胞的募集和激活至关重要，阻断CXCR3将改善脓毒症动物的预后。

DESCRIPTION (provided by applicant): We have convincingly shown that natural killer (NK) cells facilitate the pathogenesis of sepsis caused by cecal ligation and puncture (CLP). However, the mechanisms that contribute to NK cell-mediated pro-inflammatory activity during sepsis are poorly understood. Our recent studies indicate large numbers of CXCR3+ NK cells leave the spleen and enter the peritoneal cavity during CLP-induced sepsis. The CXCR3 ligands CXCL9 and CXCL10 are present at high concentrations during sepsis and CXCR3-deficient mice are resistant to CLP-induced physiologic dysfunction. Based on these observations, we hypothesize that CXCR3 signaling is critical for the recruitment and activation of NK cells and that the actions of CXCR3 are important in the pathogenesis of sepsis. The following specific aims will test these hypotheses. Specific Aim 1: To determine the importance of CXCR3 for NK cell migration and activation as well as its impact on the pathogenesis of CLP- induced sepsis. The expression of CXCR3 and markers of activation will be evaluated on NK cells at the primary site of infection and in remote tissues. Further studies will assess NK cell recruitment and activation in CXCR3-deficient mice and after blockade of CXCR3 with neutralizing antibodies. We will also determine the importance of CXCR3 in the pathogenesis of sublethal sepsis, sepsis-induced multi- organ dysfunction and septic shock. Specific Aim 2. To determine the importance of CXCR3 ligands (CXCL9 and CXCL10) for NK cell recruitment and activation as well as their impact on the pathogenesis of CLP-induced sepsis. The cellular sources of CXCR3 ligands at the primary site of infection and remote tissues will be examined. NK cell migration and activation will be studied in CXCR3 ligand-deficient mice or after blockade of CXCR3 ligands using neutralizing antibodies. Physiological function, organ injury and systemic inflammation will be examined in CXCR3 ligand- deficient mice using models of sublethal sepsis, sepsis-induced multi-organ dysfunction and septic shock. We will also determine the ability of CXCR3 ligands to directly induce the sepsis syndrome in control mice or mice with sublethal sepsis. Specific aim 3. Evaluation of factors that regulate the CXCR3 axis during CLP-induced sepsis. These studies will examine the contributions of NK cells to CXCR3 ligand production and the factors that regulate NK cell CXCR3 expression during sepsis. Although LPS-induced CXCL10 production by isolated macrophages is considered to be regulated by Trif-dependent signaling and require production of IFN2, we propose that NK cells will facilitate MyD88- dependent CXCL10 production through the production of IFN3. Studies are proposed in this application to address that assertion. Further studies will evaluate the importance of paracrine and autocrine mechanisms for NK cell CXCR3 activation and the factors that regulate CXCR3 expression by NK cells. PUBLIC HEALTH RELEVANCE: We have convincingly shown that natural killer (NK) cells facilitate the pathogenesis of sepsis. The chemokine receptor CXCR3 is known to regulate NK cell functions in some disease models. Based on our recent research, we hypothesize that CXCR3 signaling is critical for the recruitment and activation of NK cells during sepsis and that blockade of CXCR3 will improve outcome in septic animals.