Molecular Analysis Of Leukocyte Activation By Chemoattractants

这个项目的目的是确定血液白细胞迁移到炎症或感染的特定组织部位的分子机制和生物学背景。我们一直专注于介导这一过程的趋化蛋白，并鉴定了部署在白细胞表面的趋化受体大家族的成员。我们还鉴定了一组不同的趋化物质和趋化物质受体模拟物，包括疱疹病毒、痘病毒和艾滋病毒。我们使用基因组学、分子生物学、细胞生物学和流行病学作为分析这些分子的主要方法。一个主要的目标是确定单个趋化物质和趋化物质受体的特定疾病关联，以确定潜在的新的治疗靶点。一个关键的策略是分析疾病模型中基因敲除小鼠的表型，以及人类疾病队列中相应人类基因功能突变丧失的相关性。在2009财年，我们报告了在以下三种疾病中的发现：1.西尼罗河病毒的发病机制；2.动脉粥样硬化；以及3.肾缺血再灌注损伤。 1)我们发现，在健康献血者中，CCR5D32纯合子突变是WNV感染相关症状的危险因素，但不是感染本身的危险因素。这是我们之前在这一领域的工作的扩展，该工作将该基因型别确定为出现症状性疾病的患者的症状性西尼罗河病毒感染的危险因素，并将其提交给卫生保健专业人员。这项新的研究基于美国红十字会从筛查计划开始到2008年7月对3500万献血者进行的全面的西尼罗河病毒检测。最近的工作很重要，因为它为CCR5缺乏增加症状性西尼罗河病毒疾病风险的机制提供了新的见解。西尼罗河病毒的工作特别具有挑战性，因为这是一种持续出现的流行病，很难获得有用的样本。总体结果具有重要的科学意义，因为它们确定了西尼罗河病毒病的第一个遗传风险因素，以及CCR5对人类的第一个有益作用。其意义不仅限于西尼罗河病毒，还包括艾滋病毒/艾滋病，因为CCR5被艾滋病毒利用进入目标细胞，而且CCR5拮抗剂现在正被用于艾滋病毒/艾滋病患者。新的数据表明，如果接受治疗的患者感染了西尼罗河病毒，用药物阻断CCR5可能会增加出现症状的西尼罗河病毒病的风险。 2.)在2009财年，我们报道了编码人类OAS1基因的功能多态性是感染西尼罗河病毒的一个危险因素。这一结果转化为人类先前的数据，即小鼠OAS1b(人类OAS1的同源物)与黄病毒感染的易感性有关。这项工作具有重要的科学意义，因为它提供了一些第一批数据，支持内源性I型干扰素信号系统在控制人类病毒感染方面的作用，其中包括OAS1。 3.)在2009财年，我们报道了致动脉粥样硬化的脂质可以通过上调跨膜趋化因子CXCL16而诱导人巨噬细胞摄取高密度脂蛋白和胆固醇外流，而不需要依赖于CXCL16的细胞黏附。CXCL16是一种不同寻常的趋化因子，它具有三种不同的功能：黏附、趋化和清除。这项工作的科学意义在于，它为CXCL16与保护小鼠和人的动脉粥样硬化之间的遗传证据提供了解释。 4.)在2009财年，我们报道了趋化因子受体CCR1调节肾缺血再灌注损伤后炎性细胞的渗透。我们发现CCR1缺陷小鼠损伤肾脏的中性粒细胞和巨噬细胞水平显著降低，但这并不影响其功能，其下降速度与野生型小鼠损伤肾脏的下降速度相同。这些数据表明，CCR1依赖的细胞渗透对组织修复可能比对损伤更重要。

The aim of this project is to define the molecular mechanisms and biological contexts for blood leukocyte migration to specific tissue sites that are inflamed or infected. We have focused on chemoattractant proteins that mediate this process and have identified members of a large family of chemoattractant receptors that are deployed on the leukocyte cell surface. We have also identified members of a diverse group of chemoattractant and chemoattractant receptor mimics made by viruses, including herpesviruses, poxviruses and HIV. We use genomics, molecular biology, cell biology and epidemiology as the principle methods for analyzing these molecules. A major goal is to identify specific disease associations of individual chemoattractant and chemoattractant receptors, in order to identify potential new therapeutic targets. A key strategy is to analyze phenotypes of gene knockout mice in disease models as well as associations of loss of function mutations in the corresponding human genes in human disease cohorts. In FY09 we reported discoveries in the following three diseases: 1. West Nile virus pathogenesis; 2. atherosclerosis; and 3.) renal ischemia-reperfusion injury. 1.) We found that among healthy individuals donating blood, homozygous mutation CCR5D32 is a risk factor for symptoms associated with WNV infection but not for infection per se. This extends our previous work in this area that identified this genotype as a risk factor for symptomatic WNV infection in patients presenting with symptomatic illness to a health care professional. The new study was based on comprehensive WNV testing of 35 million blood donations by the American Red Cross from the start of the screening program through July, 2008. The recent work is important because it provides new insight into the mechanism by which CCR5 deficiency increases risk of symptomatic WNV disease. The WNV work is particularly challenging because this is an ongoing emerging epidemic in which it is difficult to obtain useful samples. The overall results are scientifically important because they identify the first genetic risk factor for WNV disease and the first beneficial role in humans for CCR5. The significance extends beyond WNV to HIV/AIDS since CCR5 is exploited by HIV to enter target cells and since CCR5 antagonists are now being used in patients with HIV/AIDS. The new data suggest that blocking CCR5 with a drug may increase the risk of symptomatic WNV disease should treated patients become infected with WNV. 2.) In FY09 we reported that functional polymorphism in the gene encoding human OAS1 is a risk factor for infection with West Nile virus. This result translates to human previous data associating mouse OAS1b, the homologue of human OAS1, with susceptibility to flavivirus infection. The work is scientifically important because it provides some of the first data supporting a role for the endogenous Type I interferon signaling system, which includes OAS1, in control of a viral infection in man. 3.) In FY09 we reported that atherogenic lipids can induce high-density lipoprotein uptake and cholesterol efflux in human macrophages by up-regulating transmembrane chemokine CXCL16 without engaging CXCL16-dependent cell adhesion. CXCL16 is an unusual chemokine in that it has three distinct functions: adhesion, chemotaxis and scavenging. The scientific significance of this work is that it provides an explanation for genetic evidence linking CXCL16 to protection from atherosclerosis in mouse and man. 4.) In FY09 we reported the chemokine receptor CCR1 regulates inflammatory cell infiltration after renal ischemia-reperfusion injury. We found that CCR1 deficient mice had markedly reduced levels of neutrophils and macrophages in the injured kidney, yet this did not affect function, which declined at the same rate as in injured kidney from wild type mice. The data suggest that CCR1 dependent cell infiltration may be more important for tissue repair than for injury.