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: 8735941
• 负责人: LEE ARMISTEAD DENSON
• 金额: $ 64.57万
• 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/8735941
• 关键词: Accounting; Adhesions; Adult; Affect; Age; Age of Onset; Animal Model; Antibodies; Behavior; Bioinformatics; Blood specimen; CSF2RB gene; Chemotaxis; Child; Childhood; Chronic; Clinical; Code; Complex; Crohn' s disease; DNA; Databases; Development; Diagnosis; Disease; Enrollment; Exhibits; Frequencies; Functional disorder; Gene Mutation; Genes; Genetic; Genomics; Granulocyte-Macrophage Colony-Stimulating Factor; 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; Relative (related person); Reporting; Respiratory Burst; Role; STAT5A gene; Serum; Signal Transduction; Single Nucleotide Polymorphism; Testing; Time; Variant; age related; antimicrobial; base; biobank; cohort; design; early onset; exome sequencing; experience; gene discovery; genetic variant; genome wide association study; human CYBA protein; innovation; killings; loss of function; loss of function mutation; microbial; neutrophil; novel; novel therapeutic intervention; novel therapeutics; patient population; peripheral blood; prospective; protein expression; public health relevance; 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（由申请人提供）：在儿童生命的头十年中，抗微生物血清反应性（AMS）和慢性肠道炎症类似于克罗恩病（CD） 吞噬细胞功能的遗传性疾病表明，中性粒细胞抗菌途径的功能丧失可能是小儿CD发病机理的基本机制。 CD中的GWAS仅占遗传力的一部分，很少识别出很少有效应的基因座。 GWAS无法检测到的罕见变体已被认为可以解释CD等复杂疾病的大部分，因此基因发现工作已经转移到了有害 /功能突变丧失的表征上。促核细胞巨噬细胞刺激因子（GM-CSF）需要启动中性粒细胞抗菌功能，并且基因组研究的生物信息学分析表明CD发病机理起着核心作用。我们发现，较老的小儿（早期发病，EO，10-17岁）和成年患者表现出嗜中性粒细胞功能障碍，GM-CSF自动抗体（GM-CSF AB）的获得的基础，这些基础随着年龄的增长而增加。 GM-CSF AB托架与中性粒细胞STAT5激活，吞噬能力和细菌杀伤以及AMS的高速率和狭窄行为有关。为了测试这些令人兴奋的发展的重要性，我们为1130名诊断入学的儿科CD患者建立了一个前瞻性临床数据库和生物库（风险研究）。我们发现，在一部分患者中，中性粒细胞吞噬作用和细菌杀伤减少。 VEO患者在预测会影响细菌杀伤（CSF2RB和ITGAM/CD11B）和中性粒细胞氧化爆发（CYBA/P22Phox）的基因中表现出罕见的编码区突变，而EO患者的滴度越来越多。我们假设遗传变异和GM-CSF AB会导致中性粒细胞功能障碍，从而在小儿CD中以年龄依赖性的方式促进疾病发病机理。 AIM 1：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，非常早期发作小儿CD患者。 AIM 2：测试中性粒细胞GM-CSF信号传导和细菌杀死对基因突变的功能后果。外周血样本将从携带遗传突变的风险患者中收集，这些遗传突变预测会影响GM-CSF启动和中性粒细胞功能，包括中性粒细胞候选蛋白蛋白表达/定位，GM-CSF信号传导，CD64激活，粘附，趋化性，趋化性，趋化性，氧化性爆发，吞噬细胞和细菌杀死。我们将使用 最先进的基因组和免疫方法是首次定义北美最大的儿科CD造成人群中嗜中性粒细胞功能障碍的原因和后果。总的来说，我们的研究将对新型治疗方法具有直接影响，旨在调节这种关键的宿主防御途径，以经历当前方法最糟糕的患者。