Causes and consequences of neutrophil dysfunction in early onset Crohn's disease

早发型克罗恩病中性粒细胞功能障碍的原因和后果

基本信息

批准号：
9116212
负责人：
LEE ARMISTEAD DENSON
金额：
$ 63.45万
依托单位：
EMORY UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-09-17 至 2018-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9116212
关键词：
Accounting Adhesions Adult Affect Age Age of Onset Animal Model Antibodies Behavior Bioinformatics Blood specimen CSF2RB gene CYBA gene Chemotaxis Child Childhood Chronic Clinical Code Complex Crohn&apos s disease DNA DNA Sequence Alteration Databases Development Diagnosis Disease Enrollment Exhibits Frequencies Functional disorder Gene Mutation Genes Genetic Genomics Granulocyte-Macrophage Colony-Stimulating Factor Health Heritability High-Throughput Nucleotide Sequencing Host Defense ITGAM gene Immune Inborn Genetic Diseases Individual Inflammatory disease of the intestine Injury Intestines Left Life Modeling Mutation NADPH Oxidase North America Outcome Pathogenesis Pathway interactions Patients Phagocytes Phagocytosis Pharmaceutical Preparations Play Population Reporting Respiratory Burst Role Serum Signal Transduction Single Nucleotide Polymorphism Stat5 protein Testing Time Variant age related antimicrobial base biobank cohort design early onset exome sequencing experience gene discovery genetic variant genome wide association study innovation killings loss of function loss of function mutation microbial neutrophil novel novel therapeutic intervention novel therapeutics patient population patient subsets peripheral blood prospective protein expression rare variant response

项目摘要

DESCRIPTION (provided by applicant): Anti-microbial sero-reactivity (AMS) and chronic intestinal inflammation similar to Crohn's Disease (CD) during the first decade of life in children with inherited disorders of phagocyte function suggests that loss-of-function in neutrophil antimicrobial pathways is likely to be a fundamental mechanism of pediatric CD pathogenesis. GWAS in CD have accounted for only a portion of the heritability and have rarely identified few loci of large effect. Rare variants, which GWAS are underpowered to detect, have been hypothesized to explain a substantial fraction of complex disorders like CD, so gene discovery efforts have now shifted to characterization of deleterious / loss of function mutations. Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) is required for priming of neutrophil antimicrobial function, and bioinformatic analysis of genomic studies has suggested a central role in CD pathogenesis. We discovered that older pediatric (early onset, EO, age 10-17) and adult patients exhibit an acquired basis for neutrophil dysfunction, GM-CSF auto-antibodies (GM-CSF Ab), which increase in titer with increasing age. GM-CSF Ab carriage is associated with reduced neutrophil STAT5 activation, phagocytic capacity, and bacterial killing, and high rates of AMS and stricturing behavior. To test the significance of these exciting developments, we have established a prospective clinical database and biobank for 1130 pediatric CD patients enrolled at diagnosis (the RISK study). We found that neutrophil phagocytosis and bacterial killing is reduced in a subset of patients. VEO patients have exhibited rare coding region mutations in genes predicted to affect GM-CSF priming of bacterial killing (CSF2RB & ITGAM/CD11b) and neutrophil oxidative burst (CYBA/p22phox), while EO patients have exhibited increasing titers of GM-CSF Ab. We hypothesize that genetic variants and GM-CSF Ab cause neutrophil dysfunction and thereby contribute to disease pathogenesis in an age-dependent manner in pediatric CD. Aim 1: Identify all coding genetic mutations in 127 genes likely to disrupt GM-CSF signaling and/or neutrophil function in 500 very early onset pediatric CD patients. Aim 2: Test the functional consequences of genetic mutations upon neutrophil GM-CSF signaling and bacterial killing. Peripheral blood samples will be collected from RISK patients carrying genetic mutations predicted to affect GM-CSF priming and neutrophil function including neutrophil candidate protein expression/localization, GM- CSF signaling, CD64 activation, adhesion, chemotaxis, oxidative burst, phagocytosis, and bacterial killing. We will use state-of-the-art genomic and immune approaches to define for the first time the causes and consequences of neutrophil dysfunction in the largest pediatric CD inception cohort in North America. Collectively, our studies will have direct implications for novel therapeutic approaches designed to modulate this critical host defense pathway in patients who experience the worst outcomes with current approaches.

描述（由申请人提供）：儿童生命第一个十年期间的抗微生物血清反应性（AMS）和类似于克罗恩病（CD）的慢性肠道炎症吞噬细胞功能遗传性疾病表明中性粒细胞抗菌途径功能丧失可能是儿科 CD 发病机制的基本机制。 CD 中的 GWAS 仅解释了遗传力的一部分，并且很少鉴定出少数具有大影响的基因座。 GWAS 检测能力不足的罕见变异被假设可以解释 CD 等复杂疾病的很大一部分，因此基因发现工作现在已转向有害/功能丧失突变的表征。粒细胞-巨噬细胞集落刺激因子 (GM-CSF) 是启动中性粒细胞抗菌功能所必需的，基因组研究的生物信息学分析表明其在 CD 发病机制中发挥着核心作用。我们发现，老年儿科（早发，EO，10-17 岁）和成年患者表现出中性粒细胞功能障碍的后天基础，即 GM-CSF 自身抗体 (GM-CSF Ab)，其滴度随着年龄的增加而增加。 GM-CSF Ab 携带与中性粒细胞 STAT5 激活、吞噬能力和细菌杀灭能力降低以及 AMS 和狭窄行为发生率升高相关。为了测试这些令人兴奋的发展的意义，我们为 1130 名诊断时登记的儿科 CD 患者建立了前瞻性临床数据库和生物库（RISK 研究）。我们发现部分患者的中性粒细胞吞噬作用和细菌杀灭作用减少。 VEO 患者在基因中表现出罕见的编码区突变，预计会影响 GM-CSF 杀灭细菌的启动 (CSF2RB 和 ITGAM/CD11b) 和中性粒细胞氧化爆发 (CYBA/p22phox)，而 EO 患者表现出 GM-CSF 抗体滴度增加。我们假设遗传变异和 GM-CSF Ab 会导致中性粒细胞功能障碍，从而以年龄依赖性方式促进儿科 CD 的疾病发病机制。目标 1：在 500 名极早发病儿科 CD 患者中，鉴定 127 个基因中可能破坏 GM-CSF 信号传导和/或中性粒细胞功能的所有编码基因突变。目标 2：测试基因突变对中性粒细胞 GM-CSF 信号传导和细菌杀灭的功能影响。外周血样本将从携带基因突变的 RISK 患者中采集，这些突变预计会影响 GM-CSF 启动和中性粒细胞功能，包括中性粒细胞候选蛋白表达/定位、GM-CSF 信号传导、CD64 激活、粘附、趋化性、氧化爆发、吞噬作用和细菌杀灭作用。我们将使用最先进的基因组和免疫方法首次在北美最大的儿科 CD 起始队列中定义中性粒细胞功能障碍的原因和后果。总的来说，我们的研究将对新的治疗方法产生直接影响，这些新的治疗方法旨在调节当前方法中经历最差结果的患者的这一关键宿主防御途径。