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

• 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
• 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' 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

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（由申请方提供）：儿童在出生后10年内出现与克罗恩病（CD）相似的抗微生物血清反应性（AMS）和慢性肠道炎症 与吞噬细胞功能的遗传性疾病的关系表明，中性粒细胞抗菌途径的功能丧失可能是儿科CD发病的基本机制。CD中的GWAS仅占遗传力的一部分，很少鉴定出具有大效应的少数位点。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经转向有害/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发病机制中起核心作用。我们发现，老年儿童（早发，EO，10-17岁）和成人患者表现出获得性基础的中性粒细胞功能障碍，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携带与减少的中性粒细胞STAT 5活化、吞噬能力和细菌杀伤以及高AMS率和狭窄行为相关。为了测试这些令人兴奋的发展的意义，我们已经建立了一个前瞻性的临床数据库和生物样本库的1130名儿童CD患者在诊断（风险研究）。我们发现，中性粒细胞吞噬作用和细菌杀伤在一个子集的患者减少。VEO患者在预测影响GM-CSF启动细菌杀伤（CSF 2 RB和ITGAM/CD 11b）和中性粒细胞氧化爆发（CYBA/p22 phox）的基因中表现出罕见的编码区突变，而EO患者表现出GM-CSF Ab滴度增加。我们假设遗传变异和GM-CSF Ab导致中性粒细胞功能障碍，从而以年龄依赖性方式促进儿童CD的发病机制。目标1：在500例极早发型儿童CD患者中确定可能破坏GM-CSF信号传导和/或中性粒细胞功能的127个基因中的所有编码基因突变。目的2：测试基因突变对中性粒细胞GM-CSF信号传导和细菌杀伤的功能后果。将从携带预测影响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、CD 64活化、粘附、趋化性、氧化爆发、吞噬作用和细菌杀伤）的基因突变的RISK患者中采集外周血样本。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初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，我们的研究将直接影响新的治疗方法，旨在调节这一关键的宿主防御途径的患者谁经历了最坏的结果与目前的方法。