Genetics of arthritis suscuptibility in outbred HS mice

描述(申请人提供)：关节炎疾病的致病链条仍然知之甚少，但人们认为不同的机制汇聚在一个共同的效应阶段，这涉及到先天性免疫系统的几个关键细胞和分子。在老鼠和人类身上，相当大程度的遗传变异决定了这种炎症过程。虽然已经确定了一些基因座(IL-1、C5、Ncf1)，但大多数这种遗传变异仍然未知。为了更好地了解种群的易感性，需要一种综合的视角，尽可能完整地代表物种的遗传变异。这一建议建立在一个成功的R21基础上，通过“异源股票”(HS)小鼠提供的潜力，在K/BxN模型中剖析关节炎数量性状基因座(QTL)。这些动物是由8个方正近交系通过&gt；50代杂交产生的；累积的重组事件带来了高精度QTL定位的可能性，包含了物种等位基因库的广泛代表性。通过转移K/BxN血清对600只HS小鼠进行筛查，发现33个QTL具有高分辨率(3-8Mb)和高水平的统计学意义(LOD评分和GT；10)。这一高数字反映了参与这一过程的固有细胞和分子途径的数量。将解决12个最显著的QTL背后的基因识别问题。在Aim1中，通过在QTL周围进行更密集的基因分型和测试来自定向杂交的更多小鼠，它们的位置将被细化到Mb范围。这些因果基因将通过序列分析和基因表达谱相结合的方式在方正近交系和已经筛选的HS小鼠的子集RNA中进行追踪。在AIM2中，将使用慢病毒载体通过RNA干扰创建表达亚型，并测试得到的品系对关节炎的易感性，从而对如此确定的强数量性状候选基因(QTG)进行评估。在AIM3中，将在RA患者中评估在HS小鼠中发现的QTGs的人类同源基因：将对来自24名RA患者的基因的编码和启动子区域进行测序，以确定潜在的疾病特异性变异，并将对3组RA患者(2700例+CTL)进行这些基因分型和单倍型标记的SNPs，以寻找与疾病或严重程度指数的关联。除了确定与关节炎相关的QTL外，这个项目还应该提供有关先天性免疫系统总体上的遗传变异的有价值的信息。这项拟议的项目试图确定控制关节炎炎症严重程度和破坏性后果的基因。为此，我们正在绘制在一种小鼠品系中导致严重疾病的基因，这些基因对遗传分析特别有用。一旦确定，我们将测试这些基因是否也参与了人类患者对关节炎的易感性。这些测定应该有助于更好地了解关节炎的原因，并提出治疗的新途径。

DESCRIPTION (provided by applicant): The pathogenic chain of events in arthritic diseases is still poorly understood, but it is thought that different mechanisms converge on a common effector phase, which involves several key cells and molecules of the innate immune system. A considerable degree of genetic variation, in mice and human, conditions this inflammatory process. While some loci have been identified (IL-1, C5, Ncf1), most of this genetic variation remains uncharted. In order to best understand susceptibility on a population basis, there is a need for an integrated perspective that incorporates a representation, as complete as possible, of the species' genetic variation. This proposal builds on a successful R21 to dissect arthritis Quantitative Trait Loci (QTLs) in the K/BxN model via the potential offered by "Heterogenous Stock" (HS) mice. These animals were generated from 8 founder inbred strains by >50 generations' intercrossing; the accumulated recombination events bring the potential for high-precision QTL mapping, encompassing a broad representation of the species' allele pool. A screen involving 600 HS mice tested by transfer of K/BxN serum identified 33 QTLs at high resolution (3-8 Mb) and a high level of statistical significance (LOD score >10). This high number reflects the number of innate cellular and molecular pathways involved in the process. Identification of the genes underlying the 12 most prominent QTLs will be tackled. In Aim1, their position will be refined to the Mb range by denser genotyping around the QTLs and by testing additional mice from directed crosses. The causal genes will be pursued by a combination of sequence analysis and gene-expression profiling in founder inbreds and in RNA from a subset of the HS mice already screened. In Aim2, the strong Quantitative Trait Genes candidates (QTG) thus identified will be evaluated by using lentiviral vectors to create expression hypomorphs through RNA interference, and testing the resulting lines for susceptibility to arthritis. In Aim3, the human orthologs of the QTGs identified in the HS mice will be evaluated in RA patients: coding and promoter regions of the genes from 24 RA patients will be sequenced in order to identify potential disease-specific variants, and three cohorts of RA patients (2700 cases +ctls) will be genotyped for these and haplotype-tagging SNPs, searching for association to disease or to severity indices. Beyond identifying QTLs of relevance to arthritis, this project should provide valuable information on genetic variation in the innate immune system in general. This proposed project attempts to identify genes that control the severity and destructive consequences of inflammation in arthritis. To this end, we are mapping the genes that lead to strong disease in a strain of mice particularly informative for genetic analyses. Once identified, we will test whether these genes may also be involved in setting susceptibility to arthritis in human patients. These determinations should lead to a better understanding of the causes of arthritis, and suggest novel avenues for treatments.