人类肠道中大肠杆菌的分子多样性：支持黏附侵袭性大肠杆菌（AIEC）在克罗恩病中作用的新生态学证据

Molecular diversity of Escherichia coli in the human gut: new ecological evidence supporting the role of adherent-invasive E. coli (AIEC) in Crohn's disease.

作者信息

Martinez-Medina Margarita, Aldeguer Xavier, Lopez-Siles Mireia, González-Huix Ferran, López-Oliu Carles, Dahbi Ghizlane, Blanco Jesus E, Blanco Jorge, Garcia-Gil L Jesus, Darfeuille-Michaud Arlette

机构信息

Departament de Biologia, Universitat de Girona, Girona, Spain.

出版信息

Inflamm Bowel Dis. 2009 Jun;15(6):872-82. doi: 10.1002/ibd.20860.

DOI:10.1002/ibd.20860

PMID:19235912

Abstract

BACKGROUND

Escherichia coli, particularly the adherent-invasive E. coli (AIEC) pathovar, has been increasingly implicated in the ethiopathogenesis of Crohn's disease (CD). We describe the richness, abundance, diversity, and pathogenic features of E. coli and AIEC strains that colonize the intestinal mucosa.

METHODS

Approximately 100 E. coli colonies per biopsy from 20 CD patients (18 biopsies from colon and 23 from ileum) and 28 healthy controls (C) (25, colon; 27, ileum) were isolated. Repetitive extragenic palindrome-polymerase chain reaction (Rep-PCR) and pulsed field gel electrophoresis (PFGE) were used to analyze the clonality of isolates. For AIEC identification, adhesion and invasion assays were performed over Intestine-407 cells, and the capacity to survive and replicate intracellularly was determined over macrophages J774. The serotypes, phylotypes, and genotypes (19 virulence genes) of strains were also investigated.

RESULTS

Mucosa-associated E. coli richness (E. coli subtypes/patient: C = 2.0 +/- 1.0; CD = 2.1 +/- 1.3) and diversity (Shannon Index: H'(C): 2.1 +/- 0.6; H'(CD): 2.5 +/- 0.8) were similar between CD and C, but higher E. coli counts were characteristic of CD patients (P = 0.010), particularly those with Crohn's ileitis (P = 0.001). Host-specific pulsotypes shared virulence features of ExPEC at similar frequencies between CD and C, except for iucD, which was more prevalent in E. coli from controls (C: 75%, CD: 40%, P = 0.027). In contrast, greater AIEC prevalence (% subjects with AIEC: CD = 51.9%; C = 16.7%; P = 0.003), abundance (% AIEC/E. coli: CD = 3.8 +/- 5.0%; C = 1.5 +/- 3.8%; P = 0.039), and richness (number of AIEC subtypes: CD = 0.8 +/- 1.4; C = 0.2 +/- 0.4; P = 0.015) of E. coli strains belonging to the AIEC pathovar was observed for CD patients. AIEC subtypes showed a high variability of seropathotypes and pulsotypes, although the B2 phylogroup was the most prevalent (AIEC: 64%, non-AIEC: 38%, P = 0.044).

CONCLUSIONS

New data about ecological parameters of AIEC reinforces the implication of AIEC in CD.

摘要

背景

大肠杆菌，尤其是黏附侵袭性大肠杆菌（AIEC）致病型，越来越多地被认为与克罗恩病（CD）的发病机制有关。我们描述了定植于肠黏膜的大肠杆菌和AIEC菌株的丰富度、丰度、多样性及致病特征。

方法

从20例CD患者（18例结肠活检标本和23例回肠活检标本）和28例健康对照（C）（25例结肠；27例回肠）的每份活检标本中分离出约100个大肠杆菌菌落。采用重复基因外回文序列-聚合酶链反应（Rep-PCR）和脉冲场凝胶电泳（PFGE）分析分离株的克隆性。对于AIEC鉴定，在Intestine-407细胞上进行黏附和侵袭试验，并在巨噬细胞J774上测定细胞内存活和复制能力。还研究了菌株的血清型、系统发育型和基因型（19个毒力基因）。

结果

CD患者和健康对照的黏膜相关大肠杆菌丰富度（大肠杆菌亚型/患者：C = 2.0±1.0；CD = 2.1±1.3）和多样性（香农指数：H'(C)：2.1±0.6；H'(CD)：2.5±0.8）相似，但CD患者的大肠杆菌计数较高（P = 0.010），尤其是克罗恩回肠炎患者（P = 0.001）。宿主特异性脉冲型在CD患者和健康对照中以相似频率共享肠外致病性大肠杆菌（ExPEC）的毒力特征，但iucD除外，其在对照的大肠杆菌中更普遍（C：75%，CD：40%，P = 0.027）。相反，观察到属于AIEC致病型的大肠杆菌菌株在CD患者中的AIEC患病率更高（AIEC患者百分比：CD = 51.9%；C = 16.7%；P = 0.003）、丰度更高（AIEC/大肠杆菌百分比：CD = 3.8±5.0%；C = 1.5±3.8%；P = 0.039）和丰富度更高（AIEC亚型数量：CD = 0.8±1.4；C = 0.2±0.4；P = 0.015）。AIEC亚型的血清致病型和脉冲型具有高度变异性，尽管B2系统发育群最为普遍（AIEC：64%，非AIEC：38%，P = 0.044）。