Published online Dec 14, 2017. doi: 10.3748/wjg.v23.i46.8217
Peer-review started: August 5, 2017
First decision: August 30, 2017
Revised: September 13, 2017
Accepted: November 7, 2017
Article in press: November 7, 2017
Published online: December 14, 2017
Processing time: 131 Days and 16.6 Hours
Non-anastomotic biliary stricture (NAS) is a lethal disorder after liver transplantation (LT), but the mechanisms are still obscure. Gut microbiota has been shown to participate in the pathogenesis of some post-LT complications, while the characteristics of microbial communities in patients with NAS have never been investigated.
The purpose of this study was to explore the possible relationship between fecal microbial communities and NAS after OLT.
To perform possible mechanism research about NAS after LT to shed some light on its prevention in future.
A total of 30 subjects including 10 patients with NAS, 10 patients with no complications after LT, and 10 non-LT healthy individuals were enrolled. Fecal microbial communities were assessed by the 16S rRNA gene sequencing technology. Diversity indexes and the species accumulation curve were calculated by QIIME. PCA plots of the bacterial communities were created using pcaMethods. Other data analysis was finished by Chi-square or Fisher’s exact test or ANOVA test using SPSS software.
Different from the uncomplicated and healthy groups, unbalanced fecal bacterium ratio existed in patients with non-anastomotic biliary strictures after liver transplantation. The results showed that NAS patients were associated with a decrease of Firmicutes and Bacteroidetes and an increase of Proteobacteria at the phylum level, with the proportion-ratio imbalance between potentially pathogenic families including Enterococcaceae, Streptococcaceae, Enterobacteriaceae, and Pseudomonadaceae and dominant families including Bacteroidaceae.
The compositional shifts of the increase of potential pathogenic bacterium as well as the decrease of dominant bacterium might contribute to the incidence of NAS. Gut microbiota may participate in the pathological process of NAS. Factors including poor liver graft, ABO-incompatibility, cytomegalovirus (CMV) infection contribute to the development of NAS.
Dysbacteriosis may be another inducer contributing to the development of NAS. The shifts of fecal microbial communities may participate in or exacerbate the process of bile duct injury. Unbalanced ratio of pathogenic bacteria to dominant bacteria really existed in patients with NAS after liver transplantation. What are the implications of this? Bacterial intervention may be a new therapy for preventing the occurence of NAS.
According to our study, shifts of fecal microbial communities may participate in or exacerbate the process of bile duct inflammation. This might be helpful for NAS prevention. While the definite relationship was obscure, more mechanism research about how microbiota affects the pathological process should be carried out in the future. To learn more interaction relationship between microbiota and biliary inflammatory injury, technology based on functional genomics may be used for future research.