Dysbiosis of gut microbiota in Polish patients with ulcerative colitis: a pilot study

Abstract

Ulcerative colitis (UC) is a chronic immune-mediated disorder, whose etiology is not fully understood and for which no effective treatment is available. Recently, research has focused on the dysbiosis of gut microbiome in UC. However, the results so far remain inconsistent and insufficient to understand the microbial component in UC pathogenesis. In this study, we determine specific changes in the gut microbial profile in Polish UC patients compared to healthy subjects for the first time. Using 16S rRNA gene-based analysis we have described the intestinal microbial community in a group of 20 individuals (10 UC patients and 10 controls). Our results after multiple hypothesis testing correction demonstrated substantially lower gut microbiome diversity in UC cases compared to the controls and considerable differences at the phylum level, as well as among 13 bacterial families and 20 bacterial genera (p < 0.05). UC samples were more abundant in Proteobacteria (8.42%), Actinobacteria (6.89%) and Candidate Division TM7 (2.88%) than those of healthy volunteers (2.57%, 2.29% and 0.012%, respectively). On the other hand, Bacteroidetes and Verrucomicrobia were presented at a lower level in UC relative to the controls (14% and 0% vs 27.97% and 4.47%, respectively). In conclusion, our results show a reduced gut microbial diversity in Polish UC patients, a reduction of taxa with an anti-inflammatory impact and an increased abundance of potentially pathogenic bacteria.

Figure 1

Microbial alpha diversity as OTU-richness and Shannon’s entropy in UC patients and healthy controls. p-value calculated using the non-parametric Mann–Whitney test, ^**p < 0.01, ns—no significance.

Figure 2

Individual profiles of gut microbial composition at the phylum level in the UC patient and control groups.

Figure 3

The main phylum level abundance in the gut microbiota in UC patients and healthy controls (mean values with SD).

Figure 4

Differences in microbial composition between UC patients and healthy controls at phylum, family and genus level (the fill color correspond to the mean abundance value). These data only concern initial statistically significant results calculated using the non-parametric Mann–Whitney test and asterisks mark statistical significance obtained after multiple hypothesis testing correction according to the Benjamini–Hochberg procedure. ^**p < 0.01, ^*p < 0.05, ns—no significance.

Figure 5

Projection of the variables at phylum level on the two dimensions biplot for UC patients (left) and controls (right).

Figure 6

Flowchart of literature search.

Figure 7

Forest plot of random-effects meta-analysis including studies evaluating the abundance of Streptococcaceae in UC patients versus healthy controls.

Figure 8

Forest plot of random-effects meta-analysis including studies evaluating the abundance of Christensenellaceae in UC patients versus healthy controls.

Figure 9

Forest plot of random-effects meta-analysis including studies evaluating the abundance of Phascolarctobacterium in UC patients versus healthy controls.

Figure 10

Forest plot of random-effects meta-analysis including studies evaluating the abundance of Anaerostipes in UC patients versus healthy controls.

Figure 11

Forest plot of random-effects meta-analysis including studies evaluating the abundance of Streptococcus in UC patients versus healthy controls.

Figure 12

Forest plot of random-effects meta-analysis including studies evaluating the abundance of Ruminococcus in UC patients versus healthy controls.