Martinez-Medina Margarita, Aldeguer Xavier, Gonzalez-Huix Ferran, Acero Doroteo, Garcia-Gil L Jesús
Laboratory of Molecular Microbiology, Department of Biology, University of Girona, E-17071 Girona, Spain.
Inflamm Bowel Dis. 2006 Dec;12(12):1136-45. doi: 10.1097/01.mib.0000235828.09305.0c.
Bacteria might play a role in the pathogenesis of Crohn's disease (CD), and patients harbor a different type and density of gut microbiota compared with normal healthy subjects. Thus, the aim of this study was to compare the microbiota adhered to the mucosa of CD patients with that of healthy subjects.
Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) of 16S rRNA gene fragments was used to identify the dominant bacterial species present in fresh biopsy samples obtained from the mucosa of 15 healthy and 19 CD subjects. Two patients suffering from ulcerative colitis and 1 suffering from ischemic colitis also were included.
Individuals were clustered in 2 groups according to their molecular fingerprint, which differentiated the majority of CD specimens (88.2%) from the majority of healthy/ulcerative colitis/ischemic colitis specimens (82.3%). In addition, the patient-to-patient variability in microbiota was greater within the CD cluster than in the healthy/ulcerative colitis cluster (P = 0.000). One hundred forty-one sequences were obtained from the PCR-DGGE bands that were grouped into 58 different phylotypes, 8 of which were novel. BLAST analysis revealed that 74.5% of the sequences were similar to those of bacteria that have never been cultivated. In CD samples, prevalence values for Clostridium spp Ruminococcus torques and Escherichia coli were significantly higher, whereas Faecalibacterium was more frequently found in healthy specimens. Opportunistic pathogenic gamma-proteobacteria were found occasionally, only in CD mucosal microbiota.
Microbiota attached to the ileocolonic mucosa of CD patients is distinguishable from that of healthy subjects. We postulate that individuals who are predisposed to CD are less able to regulate the microbial makeup of their intestines, which leads to an unstable microbial population.
细菌可能在克罗恩病（CD）的发病机制中起作用，与正常健康受试者相比，CD患者肠道微生物群的类型和密度有所不同。因此，本研究的目的是比较CD患者与健康受试者黏膜上附着的微生物群。
采用16S rRNA基因片段的聚合酶链反应-变性梯度凝胶电泳（PCR-DGGE）来鉴定从15名健康受试者和19名CD患者的黏膜获取的新鲜活检样本中存在的优势细菌种类。还纳入了2名溃疡性结肠炎患者和1名缺血性结肠炎患者。
根据分子指纹图谱，个体被聚类为两组，该图谱区分了大多数CD标本（88.2%）与大多数健康/溃疡性结肠炎/缺血性结肠炎标本（82.3%）。此外，CD聚类中微生物群的患者间变异性大于健康/溃疡性结肠炎聚类（P = 0.000）。从PCR-DGGE条带中获得了141个序列，这些序列被分为58个不同的系统发育型，其中8个是新的。BLAST分析显示，74.5%的序列与从未培养过的细菌序列相似。在CD样本中，梭菌属、扭链瘤胃球菌和大肠杆菌的流行率值显著更高，而在健康标本中更常发现粪杆菌属。仅在CD黏膜微生物群中偶尔发现机会性致病γ-变形菌。
CD患者回结肠黏膜上附着的微生物群与健康受试者的不同。我们推测，易患CD的个体调节其肠道微生物组成的能力较弱，这导致微生物群落不稳定。
