Genetic Analysis of Complex Inflammatory Disorders

类风湿关节炎 在过去的一年里，类风湿性关节炎的基因研究继续进行合作项目。我们为一项研究提供了NARAC复制病例和对照的基因类型，该研究确定了类风湿性关节炎和乳糜泻之间共有的14个非人类白细胞抗原基因座。以前对每种疾病的疾病易感基因座进行的全基因组关联研究发现，这两种疾病有6个共同的基因座，并暗示可能存在额外的基因座。因此，我们对现有的两个大型全基因组关联数据集(类风湿性关节炎和乳糜泻)进行了荟萃分析，样本超过38,000个。在对其他复制样本(2,169例乳糜泻病例和2,255例对照，2,845例类风湿关节炎病例和4,944例对照)的顶级相关单核苷酸多态(SNPs)进行基因分型后，另外8个SNP显示P<5倍10到负的八分之一，包括4个以前在一种疾病中发现的SNPs延伸到另一种疾病中，以及4个以前在这两种疾病中都未被证实的SNPs。14个共有的乳糜泻风险基因：TNFRSF14、IL2/IL21、TNFAIP3、CTLA4、REL、TAGAP、SH2B3、8q24.2、TRAF1、STAT4、DDX6、CD247、UBE2L3和UBASH3A，表明T细胞受体信号转导是RA和乳糜泻发病机制的关键共同途径。 我们还为NARAC收集提供了基因数据，用于开发和证明一种简单的新方法的有效性，该方法将相关个体纳入病例对照关联研究。这对于充分利用样本收集中的最大信息尤其重要，例如NARAC样本收集，这些样本是针对兄弟姐妹或其他家庭关系样本收集的。 PFAPA 在过去的一年里，我们完成了对发烧期间和发烧间歇期的PFAPA患者的全面研究。虽然我们观察到PFAPA患者经常有亲属在童年经历一个或多个PFAPA特征，但并不存在孟德尔式的遗传模式，其发病机制尚不清楚。使用系统生物学方法，我们在基因测试后分析了PFAPA患者的血液样本，以排除其他已知的遗传性周期性发热(HPF)，来自健康儿童和儿童HPF患者。基因表达谱清楚地区分了PFAPA患者的症状期和无症状期，以及HPF儿童的症状期。在有症状的PFAPA发作期间，补体(C1QB、C2、SERPING1)、白介素1相关基因(IL1B、IL1RN、CASP1、IL18RAP)和干扰素诱导的基因(AIM2、IP10/CXCL10)显著过表达，而T细胞相关转录本(CD3、CD8B)表达下调。在蛋白水平上，有症状的PFAPA发作表现为血清粒细胞集落刺激因子、促炎细胞因子(IL-18、IL-6)和活化T淋巴细胞趋化因子(IP-10/CXCL10、MIG/CXCL9)水平显著升高。在PFAPA发作期间，也注意到相对的淋巴细胞减少。活化的CD4+/CD25+T淋巴细胞计数与血清IP-10/CXCL10浓度呈负相关，与IL-1受体拮抗剂浓度呈正相关。根据IL-1β在PFAPA斑块中激活的证据，我们在斑块开始时使用重组IL-1受体拮抗剂治疗5例PFAPA患者，所有5例患者都表现出迅速的临床和IP-10/CXCL10反应。这些数据表明，在有症状的PFAPA发作期间，宿主来源的补体、IL-1β和IL-18被激活，并诱导Th1趋化因子，随后激活的T细胞保留在周围组织中。因此，抑制IL-1可能有利于治疗PFAPA的发作，IP-10/CXCL10可能是一个潜在的新的生物标志物。今年早些时候，这项研究发表在PNAS上。

Rheumatoid arthritis Genetic studies in rheumatoid arthritis continued with collaborative projects over the past year. We contributed genotypes of NARAC replication cases and controls to a study that identified fourteen non-HLA loci in common between rheumatoid arthritis and celiac disease. Previous genome-wide association studies for disease susceptibility loci for each disease found 6 loci in common for the two diseases and suggested that additional loci likely exist. We therefore performed a meta-analysis of two existing large genome-wide association datasets (RA and celiac disease) with over 38,000 combined samples. After genotyping the top associated single nucleotide polymorphisms (SNPs) in additional replication samples (2,169 celiac disease cases and 2,255 controls, and 2,845 RA cases and 4,944 controls), eight additional SNPs demonstrated P less than 5 times 10 to the negative eighth, including four SNPs previously identified in one disease that were extended to the other disease and four SNPs that have not been previously confirmed in either disease. The fourteen shared celiac disease-RA risk loci, TNFRSF14, IL2/IL21, TNFAIP3, CTLA4, REL, TAGAP, SH2B3, 8q24.2, TRAF1, STAT4, DDX6, CD247, UBE2L3, and UBASH3A, point to T-cell receptor signaling as a key shared pathway of disease pathogenesis for RA and celiac disease. We also contributed genotype data for the NARAC collection that were used to develop and demonstrate the effectiveness of a simple new method to include related individuals in case control association studies. This is particularly important to leverage the maximum information from collections of samples such as the NARAC collection, which were collected targeting sib-pair or other family relationship samples. PFAPA During the last year we have completed a comprehensive study of patients with PFAPA during and between febrile episodes. Although we have observed that PFAPA patients frequently have relatives who experienced one or more features of PFAPA in childhood, there is not a Mendelian pattern of inheritance, and the pathogenesis is unknown. Using a systems biology approach we analyzed blood samples from PFAPA patients after genetic testing to exclude other known hereditary periodic fevers (HPFs), from healthy children, and from pediatric HPF patients. Gene expression profiling clearly distinguished symptomatic and asymptomatic periods in PFAPA patients and symptomatic periods in children with HPFs. During symptomatic PFAPA episodes, complement (C1QB, C2, SERPING1), interleukin (IL)-1-related (IL1B, IL1RN, CASP1, IL18RAP), and interferon-induced (AIM2, IP10/CXCL10) genes were significantly overexpressed, while T cell-associated transcripts (CD3, CD8B) were downregulated. At the protein level, symptomatic PFAPA episodes manifested significantly increased serum levels of granulocyte colony-stimulating factor, proinflammatory cytokines (IL-18, IL-6), and chemokines for activated T lymphocytes (IP-10/CXCL10, MIG/CXCL9). A relative lymphopenia was also noted during PFAPA attacks. Activated CD4 positive/CD25 positive T lymphocyte counts correlated negatively with serum concentrations of IP-10/CXCL10, but positively with those of IL-1 receptor antagonist. Based on the evidence for IL-1beta activation in PFAPA flares, we treated five PFAPA patients with a recombinant IL-1 receptor antagonist at the beginning of a flare and all five demonstrated a prompt clinical and IP-10/CXCL10 response. These data suggest a host-derived activation of complement, IL-1beta, and IL-18 during symptomatic PFAPA episodes, with induction of Th1-chemokines and subsequent retention of activated T cells in peripheral tissues. IL-1 inhibition may thus be beneficial for the treatment of PFAPA attacks, with IP-10/CXCL10 serving as a potential new biomarker. Earlier this year this work was published in the PNAS.