Bacterial Characteristics of Intestinal Tissues From Patients With Crohn's Disease.

Desen Sun,Zhengping Xu,Yaxin Liu,Shasha Tang,Xiaolong Ge,Yuping Zhou,Liang Luo,Jinghao Sheng,Wei Zhou,Jun Sun

doi:10.3389/fcimb.2021.711680

Abstract

Background and AimsIt is believed that intestinal bacteria play an indispensable role in promoting intestinal inflammation. However, the characteristics of these tissue-associated bacteria remain elusive. The aim of this study is to explore the bacterial loads, compositions, and structures in the noninflamed mucosa, inflamed mucosa, and creeping fat taken from patients with Crohn’s disease (CD).MethodsNoninflamed mucosa, inflamed mucosa, and creeping fat samples were obtained from 10 surgical patients suffering from CD. Total bacterial DNA was extracted in a sterile environment using aseptic techniques. The V3–V4 regions of bacterial 16S rDNA were amplified and analysed using standard microbiological methods. qPCR was used to confirm the change in abundance of specific species in additional 30 independent samples.ResultsInflamed mucosa exhibited the highest bacterial load (3.8 and 12 times more than that of non-inflamed mucosa and creeping fat) and species diversity. The relative abundance of Proteobacteria was dominant in most samples and was negatively associated with Firmicutes. Moreover, the relative abundances of Methylobacterium and Leifsonia in creeping fat significantly increased more than twice as much as other tissue types. The bacterial community structure analysis showed that the bacterial samples from the same individual clustered more closely.ConclusionThis study reveals the significant differences in bacterial load, species diversity, and composition among different intestinal tissue types of CD patients and confirms that the bacterial samples from the same individual are highly correlated. Our findings will shed light on fully revealing the characteristics of tissue-associated bacteria and their roles in CD pathogenesis.

Highlights

Crohn’s disease (CD), one major phenotype of inflammatory bowel disease (IBD), is a chronic inflammatory disease of the gastrointestinal tract with symptoms such as chronic abdominal pain, diarrhoea, obstruction, and/or perianal lesions (Torres et al, 2017; Roda et al, 2020)
It has been reported that the CD microbiome displays more severe dysbiosis than that found in healthy controls and patients with ulcerative colitis (UC), another type of IBD
In addition to the dysbiosis found in the gut lumen, it has been suggested that intestinal tissue-associated bacteria may play an important role in CD (Yu, 2018)

Summary

Introduction

Crohn’s disease (CD), one major phenotype of inflammatory bowel disease (IBD), is a chronic inflammatory disease of the gastrointestinal tract with symptoms such as chronic abdominal pain, diarrhoea, obstruction, and/or perianal lesions (Torres et al, 2017; Roda et al, 2020). The pathogenesis of CD involves a complex interaction among susceptibility genes, environmental factors, and altered gut microbiota (Torres et al, 2017; Roda et al, 2020). The most consistent bacterial changes in CD include reduced species diversity, higher gut microbiota structure instability, lower abundance of “protective” bacteria, and the higher abundance of “harmful” bacteria (Schaubeck et al, 2016; Pascal et al, 2017). In addition to the dysbiosis found in the gut lumen, it has been suggested that intestinal tissue-associated bacteria may play an important role in CD (Yu, 2018). The aim of this study is to explore the bacterial loads, compositions, and structures in the noninflamed mucosa, inflamed mucosa, and creeping fat taken from patients with Crohn’s disease (CD)

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