Adherent Escherichia coli and associated virulence genes in children with IBD

描述（由申请人提供）： 慢性复发性肠道炎症似乎是由遗传易感个体对肠道（非致病性）细菌的先天性和获得性免疫应答失调介导的。我们以前证明，白细胞介素-10缺乏（IL-10-/-）小鼠选择性地与大肠杆菌（NC 101）或粪肠球菌（OG 1 RF）的非致病性菌株定植（单相关），发展不同的结肠炎表型，具有明显的区域和动力学差异，不同的大肠杆菌。大肠杆菌菌株在单相关IL-10-/-小鼠中差异诱导结肠炎。不同E.大肠杆菌菌株引起结肠炎与体内上皮粘附、体外上皮细胞内侵入和巨噬细胞内持久性的程度相关。我们还发现，尿路致病性大肠杆菌所共有的几个细菌毒力因子。大肠杆菌菌株在我们的大肠杆菌NC 101中增加。coli菌株和几株粘附/侵袭性E.大肠杆菌（AIEC）菌株分离自克罗恩病患者。与溃疡性结肠炎儿童和健康个体相比，具有介导细菌杀伤的遗传多态性的克罗恩病儿童中，介导细菌粘膜粘附、侵袭和细胞内存活的大肠杆菌相关毒力因子增加。我们还假设，在克罗恩氏回肠炎与结肠炎中，这些细菌毒力因子具有区域特异性。最终，克罗恩病的诱导需要宿主遗传易感性和特定细菌基因的表达。这些假设通过以下具体目标得以解决： 具体目标1：表征粘膜粘附的E. coli和E.来自粘膜活检样品的大肠杆菌相关的毒力因子（a）在克罗恩病儿童与溃疡性结肠炎儿童的回肠和结肠的不同区域中，以及对照个体（正常对照和自限性感染性结肠炎），和（B）在克罗恩病儿童的肠的不同区域之间。 具体目标2：确定调节细菌加工和杀灭的基因（NOD 2、ATG 16 L1、IRGM）的多态性是否与（a）AIEC肠内粘膜定植和（B）增加的大肠杆菌数量相关。克罗恩病患儿大肠杆菌毒力基因的表达 本申请将描述宿主与功能改变的大肠杆菌的遗传相互作用.大肠杆菌及其相关毒力基因在IBD儿童和青少年中的表达，并将这些发现与宿主基因型相关联。 公共卫生相关性：完成本提案将确定特定的优势大肠杆菌。大肠杆菌毒力基因在小儿克罗恩病中的出现频率较高，这些因素具有区域特异性，并将其存在与疾病基因型相关。此外，这些研究将描述宿主与功能改变的E.大肠杆菌及其相关毒力基因。最终，这些研究将帮助我们更好地理解浮游生物之间的关系，如E。大肠杆菌，遗传易感个体处理这些生物体的能力，以及随后参与疾病发病机制的代谢途径。

DESCRIPTION (provided by applicant): Chronic relapsing intestinal inflammation appears to be mediated by dysregulated innate and acquired immune responses to commensal (nonpathogenic) bacteria in genetically predisposed individuals. We previously demonstrated that interleukin - 10 deficient (IL-10-/-) mice selectively colonized (monoassociated) with non-pathogenic strains of Escherichia coli (NC101) or Enterococcus faecalis (OG1RF) develop different phenotypes of colitis with clear regional and kinetic differences, and that different E. coli strains differentially induce colitis in monoassociated IL-10-/- mice. The selective ability of the different E. coli strains to cause colitis correlates with the degree of epithelial adherence in vivo, epithelial intracellular invasion in vitro, and intracellular persistence in macrophages. We also have shown that several bacterial virulence factors shared by uropathogenic E. coli strains are increased in our colitogenic NC101 E. coli strain and several adherent/invasive E. coli (AIEC) strains isolated from Crohn's disease patients.3 Therefore, we hypothesize that E. coli- associated virulence factors that mediate bacterial mucosal adherence, invasion, and intracellular survival are increased in children with Crohn's disease with genetic polymorphisms that mediate bacterial killing versus children with ulcerative colitis and healthy individuals. We also hypothesize that there is regional specificity of these bacterial virulence factors in Crohn's ileitis versus colitis. Ultimately, the induction of Crohn's disease requires both host genetic susceptible and expression of specific bacterial genes. These hypotheses are addressed by the following Specific Aims: Specific aim 1: Characterize the frequency of mucosally - adherent E. coli, and E. coli - associated virulence factors from mucosal biopsy samples (a) in the ileum and different regions of the colon of children with Crohn's disease versus children with ulcerative colitis, and control individuals (normal controls and self-limited infectious colitis), and (b) between different regions of the intestine within children with Crohn's disease. Specific aim 2: Determine if polymorphisms of genes that regulate bacterial processing and killing (NOD2, ATG16L1, IRGM) are associated with (a) mucosal colonization in the intestine of AIEC, and (b) increased E. coli virulence gene expression in children with Crohn's disease This application will delineate host - genetic interactions with functionally altered E. coli and their associated virulence genes in children and adolescents with IBD and correlating these findings with host genotype. PUBLIC HEALTH RELEVANCE: Completion of this proposal will identify specific dominant E. coli virulence genes present at a higher frequency in pediatric Crohn's disease and regional specificity of these factors and correlate their presence with disease genotype. In addition, these studies will delineate host - genetic interactions with functionally altered E. coli and their associated virulence genes. Ultimately, these studies will help us develop a better understanding of the relationship between commensal organisms such as E. coli, the genetically susceptible individual's ability to process these organisms, and subsequent metabolic pathways involved in disease pathogenesis.