Adherent Escherichia coli and associated virulence genes in children with IBD

描述(由申请人提供)： 慢性复发性肠炎似乎是由遗传易感个体对共生(非致病)细菌的先天性和获得性免疫反应失调所介导的。我们先前已经证明，白介素10缺陷(IL-10-/-)小鼠选择性地与非致病菌株大肠杆菌(NC101)或粪肠球菌(OG1RF)共同定植(单相关)会发生不同的结肠炎表型，具有明显的区域性和动力学差异，并且不同的大肠杆菌菌株不同地诱导单相关的IL-10-/-小鼠结肠炎。不同菌株对结肠炎的选择性与体内上皮细胞黏附程度、体外上皮细胞内侵袭和巨噬细胞内持续时间有关。我们还表明，在我们的结肠炎NC101大肠杆菌株和从克罗恩病患者中分离的几株粘附性/侵袭性大肠杆菌(AIEC)中，几种致病性大肠杆菌共有的细菌毒力因子都会增加。3因此，我们假设，与溃疡性结肠炎儿童和健康人相比，介导细菌粘膜黏附、侵袭和细胞内生存的大肠杆菌相关毒力因子增加了，其基因多态性介导了细菌杀灭。我们还假设，在克罗恩回肠炎和结肠炎中，这些细菌毒力因子具有地区性特异性。最终，克罗恩病的诱发需要宿主的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到解决： 具体目标1：从黏膜活检标本(A)克隆氏病患儿与溃疡性结肠炎患儿、对照组(正常对照和自限性感染性结肠炎)的回肠和结肠不同区域，以及(B)克隆氏病患儿不同肠段之间的粘膜活检标本中，鉴定粘附性大肠杆菌和大肠杆菌相关毒力因子的频率。 具体目标2：确定调控细菌加工和杀伤的基因(NOD2、ATG16L1、IRGM)的多态性是否与(A)AIEC肠道粘膜定植和(B)克罗恩病儿童大肠杆菌毒力基因表达增加有关 这项应用将描绘患有IBD的儿童和青少年中宿主-遗传与功能改变的大肠杆菌及其相关毒力基因的相互作用，并将这些发现与宿主基因相关联。 公共卫生相关性：这项建议的完成将确定在儿童克罗恩病中出现频率较高的特定显性大肠杆菌毒力基因和这些因素的区域特异性，并将它们的存在与疾病基因相关联。此外，这些研究将描绘宿主-遗传与功能改变的大肠杆菌及其相关毒力基因的相互作用。最终，这些研究将有助于我们更好地了解共生生物(如大肠杆菌)、遗传易感个体处理这些生物的能力与随后参与疾病发病机制的代谢途径之间的关系。

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.