Changes in gut microbiota composition and diversity associated with post-cholecystectomy diarrhea

Abstract

Background: Post-cholecystectomy diarrhea (PCD) frequently occurs in patients following gallbladder removal. PCD is part of the post-cholecystectomy (PC) syndrome, and is difficult to treat. After cholecystectomy, bile enters the duodenum directly, independent of the timing of meals. The interaction between the bile acids and the intestinal microbes is changed. Therefore, the occurrence of PCD may be related to the change in microbiota. However, little is known about the relationship between the gut microbiota and PCD.

Aim: To better understand the role of the gut microbiota in PCD patients.

Methods: Fecal DNA was isolated. The diversity and profiles of the gut microbiota were analyzed by performing high-throughput 16S rRNA gene sequencing. The gut microbiota were characterized in a healthy control (HC) group and a PC group. Subsequently, the PC group was further divided into a PCD group and a post-cholecystectomy non-diarrhea group (PCND) according to the patients' clinical symptoms. The composition, diversity and richness of microbial communities were determined and compared.

Results: In the PC and HC groups, 720 operational taxonomic units (OTUs) were identified. The PC group had fewer OTUs than the HC group. β-diversity was decreased in the PC group. This indicated decreased microbial diversity in the PC group. Fifteen taxa with differential abundance between the HC and PC groups were identified. In the PCD group compared to the PCND group, significant decreases in microbial diversity, Firmicutes/Bacteroidetes ratio, and richness of probiotic microbiota (Bifidobacterium and Lactococcus), and an increase in detrimental microbiota (Prevotella and Sutterella) were observed. Moreover, a negative correlation was found between Prevotella and Bifidobacterium. Using a Kyoto Encyclopedia of Genes and Genomes functional analysis, it was found that the abundances of gut microbiota involved in lipid metabolism pathways were markedly lower in the PCD group compared to the PCND group.

Conclusion: This study demonstrated that gut dysbiosis may play a critical role in PCD, which provides new insights into therapeutic options for PCD patients.

Keywords: 16S rRNA; Bifidobacterium; Cholecystectomy; Diarrhea; Microbiota; Post-cholecystectomy.

Figure 1

Comparison of gut microbiota structure and abundance between the healthy control and post-cholecystectomy groups. A: Venn diagram comparing the operational taxonomic units in the fecal microbiota between the two groups; B: Phylogenetic diversity tree used to estimate the diversity of the gut microbiota; C: Profiling of bacterial taxa at the genus level; D: Logarithmic linear discriminant analysis score identifying the taxa with the greatest differences in abundance between the healthy control and post-cholecystectomy groups. The brightness of each dot is proportional to the effect size. HC: Healthy control; PC: Post-cholecystectomy.

Figure 2

Comparison of gut microbiota structure and abundance between the post-cholecystectomy diarrhea and post-cholecystectomy non-diarrhea groups. A: Differences between and within post-cholecystectomy diarrhea (PCD) and post-cholecystectomy non-diarrhea (PCND) groups were assessed by one-way analysis of similarities and nonmetric multidimensional scaling analysis of the gut microbiota based on the weighted UniFrac metric; B: Comparison of the relative abundance at the phylum level between the PCD and PCND groups; C: Linear discriminant analysis effect size analysis showing the taxa with the greatest differences in abundance between the PCD and PCND groups. Green bars: PCD group-enriched taxa; yellow bars: PCND group-enriched taxa. The brightness of each dot is proportional to the effect size; D: Box plots showing the relative abundance of the top 20 microbial taxa with differential abundance. PCD: Post-cholecystectomy diarrhea; PCND: Post-cholecystectomy non-diarrhea; LDA: Linear discriminant analysis.

Figure 3

Principal component analyses and correlation plots of different microbial taxa in the post-cholecystectomy diarrhea and post-cholecystectomy non-diarrhea groups. A: Principal component analysis plot of different taxa in the post-cholecystectomy diarrhea and post-cholecystectomy non-diarrhea groups; B: Spearman’s correlation plots of the relative abundances of the differentially abundant bacteria at the genus level. Statistical significance was determined for all pairwise comparisons. Positive values (blue circles) indicate positive correlations, and negative values (red circles) indicate negative correlations. The shade and size of each circle indicate the magnitude of the correlation (with darker shades indicating higher correlations). PCD: Post-cholecystectomy diarrhea; PCND: Post-cholecystectomy non-diarrhea.

Figure 4

Kyoto Encyclopedia of Genes and Genomes functional categories of microbiota with differential abundance. A: Comparison between the post-cholecystectomy diarrhea-enriched and post-cholecystectomy non-diarrhea-enriched markers regarding the Kyoto Encyclopedia of Genes and Genomes level 2 functional categories; B: Comparison between the post-cholecystectomy diarrhea-enriched and post-cholecystectomy non-diarrhea-enriched markers regarding the Kyoto Encyclopedia of Genes and Genomes level 3 functional categories. PCD: Post-cholecystectomy diarrhea; PCND: Post-cholecystectomy non-diarrhea; LDA: Linear discriminant analysis.