Abstract
PurposeUlcerative colitis (UC) as a type of inflammatory bowel disease (IBD), presumed to occur as a consequence of increased immune responses to intestinal microbiota in genetically susceptible individuals. Enterotoxigenic Bacteroides fragilis (ETBF) strains are important intestinal bacteria that can be involved in IBD. The aim of this study was to design a quantitative assay for detection of B. fragilis and ETBF and also to find their association with UC.MethodsNinety-five biopsies were collected from patients with UC (n = 35) and with no IBD (nIBD, n = 60). All the specimens were cultured in Bacteroides bile esculin agar medium. Specific primers and probes were designed for quantitative real-time PCR (QRT-PCR) based on 16S rRNA and bft genes sequences of ETBF.ResultsThe bft genes were detected in 51.4% of UC samples and 1.6% of nIBD samples, respectively. In UC patients, 37.1% of samples with diarrhea and 11.4% of samples without diarrhea, harbored the bft gene. Mean value of the number of ETBF with bft gene in UC and nIBD samples were 4.46 ן 102 and 1.96, respectively. Likewise these result for 16S rRNA gene in UC and nIBD samples were 2.0 × 103 and 8.4 × 103, respectively.ConclusionsThere was no significant association between presence and numbers of 16S rRNA gene of B. fragilis and UC. ETBF was detected more in UC specimens and biopsies of UC patients with diarrhea than in the control group. These data demonstrated that ETBF is associated with development of UC and as a causative agent for the development of diarrhea in these patients.
Highlights
Ulcerative colitis (UC) is a type of human inflammatory bowel disease (IBD) caused by improper activation of the intestinal mucosa as a consequence of combination of interactive factors such as genetic, immunological and environmental [1, 2]
We found that 51.4% of UC samples harbored bft gene, an increased rate of enterotoxigenic B. fragilis (ETBF), compared to the preceding reports [16]
In conclusion, considering the real time results for bft1 gene, the high incidence of ETBF in mucosal biopsies of UC patients was statistically significant
Summary
Ulcerative colitis (UC) is a type of human inflammatory bowel disease (IBD) caused by improper activation of the intestinal mucosa as a consequence of combination of interactive factors such as genetic, immunological and environmental [1, 2]. The intestinal microbiota affects some important functions such as the activity of epithelial cells, immune regulation and intestinal mucosal inflammation [2]. The composition of intestinal microbiota in the fecal and mucosal surface is different. The permeability of the gut epithelial cells can be enhanced as a consequence of B. fragilis enterotoxin (BFT), resulting in the intensification of internalization of different enteric bacteria. This action is considered as one of the important routes for delivering an antigen to the active immune cells and initiating a tissue invasion [15]. ETBF functions can lead to severe inflammation in IBD, resulting in Crohn’s disease (CD) and UC as well as diarrhea and colorectal cancer (CRC) [3, 16,17,18,19,20]
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