Intestinal Bacteria Composition and Translocation of Bacteria in Inflammatory Bowel Disease

Spyros Vrakas,George Papatheodoridis,George Papatheodoridis,Charalampos Tzathas,Konstantinos C Mountzouris,George Michalopoulos,Maria Gazouli,George Karamanolis,Leonardo A Sechi

doi:10.1371/journal.pone.0170034

Abstract

BackgroundLive commensal intestinal bacteria are present in the peripheral blood where they can induce inflammation.ObjectiveTo evaluate the intestinal bacteria composition and translocation of bacteria in IBD.MethodsBoth blood and tissue biopsy samples were collected from adult patients with active/inactive Crohn’s disease (CD), active/inactive ulcerative colitis (UC) and healthy individuals. Most of the patients were newly diagnosed and none of them received antibiotics. Using a reverse transcription–quantitative real-time PCR (RT-qPCR) method, we determined the composition of microbiota. NOD2/CARD15 genotyping was also studied.ResultsTotal bacterial DNA concentration was increased in tissue and blood samples of IBD patients compared to healthy controls. Furthermore, the active IBD cases had higher total bacterial DNA concentration levels compared to the inactive cases. Three species characterized dysbiosis in IBD, namely an increase of Bacteroides spp in active and inactive IBD samples, and a decrease in Clostridium leptum group (IV), and Faecalibacterium prausnitzi in both active and inactive IBD patients. No significant association between bacterial translocation and NOD2/CARD15 mutations was found.ConclusionsThe composition of the microbiota in IBD patients differs from that of healthy controls. The high rate of bacterial DNA in the blood samples indicates translocation in inflammatory bowel disease.

Highlights

The exact cause of Inflammatory bowel disease (IBD), consisting of Crohn’s disease (CD) and ulcerative colitis (UC) is unknown
Total bacterial DNA concentration was increased in tissue and blood samples of IBD patients compared to healthy controls
The active IBD cases had higher total bacterial DNA concentration levels compared to the inactive cases

Summary

Introduction

The exact cause of Inflammatory bowel disease (IBD), consisting of Crohn’s disease (CD) and ulcerative colitis (UC) is unknown. The gut microbiota in healthy people is dominated by the bacteria phyla Firmicutes, and Bacteroidetes and to a lesser extent by Proteobacteria, and Verrucomicrobia [6]. Concerning IBD, Wills et al [7] reported larger changes in the bacterial community composition between remission and exacerbation in CD patients in comparison to UC patients. Forbes JD et al [10] found an increase in the levels of Bacteroidetes, and Fusobacteria in inflamed CD mucosa, Proteobacteria, and Firmicutes were more frequently observed in inflamed UC patients. In an Indian population, Kabeerdoss et al [13] found greater Bacteroides and Lactobacillus concentration in inflamed colonic mucosa of patients with UC in comparison to CD patients. Live commensal intestinal bacteria are present in the peripheral blood where they can induce inflammation

Methods

Results

Conclusion