Bile reflux alters the profile of the gastric mucosa microbiota

Abstract

BackgroundBile reflux can cause inflammation, gastric mucosa atrophy, and diseases such as stomach cancer. Alkaline bile flowing back into the stomach affects the intragastric environment and can alter the gastric bacterial community. We sought to identify the characteristics of the stomach mucosal microbiota in patients with bile reflux.MethodsGastric mucosal samples were collected from 52 and 40 chronic gastritis patients with and without bile reflux, respectively. The bacterial profile was determined using 16S rRNA gene analysis.ResultsIn the absence of H. pylori infection, the richness (based on the Sobs and Chao1 indices; P <0.05) and diversity (based on Shannon indices; P <0.05) of gastric mucosa microbiota were higher in patients with bile reflux patients than in those without. There was a marked difference in the microbiota structure between patients with and without bile reflux (ANOSIM, R=0.058, P=0.011). While the genera, Comamonas, Halomonas, Bradymonas, Pseudomonas, Marinobacter, Arthrobacter, and Shewanella were enriched in patients with bile reflux, the genera, Haemophilus, Porphyromonas, and Subdoligranulum, were enriched in those without bile reflux.ConclusionOur results demonstrate that bile reflux significantly alters the composition of the gastric microbiota.

Effect of bile reflux on gastric juice microbiota in patients with different histology phenotypes

“…The microbial compositional comparison using beta-diversity analysis also showed significant differences according to BR, histological phenotype, and H. pylori infection, although no significant differences were observed between grades in the same categories (i.e., BR1 vs. BR2; LGD vs. EGC). Our results were inconsistent with previous studies that showed no difference in the beta diversity in the gastric mucosal microbiota between patients with and without BR [ 19 , 20 ]. As we discussed the inconsistent results for the effect of H. pylori infection on α-diversity between mucosal samples and gastric juice samples [ 19 , 20 ], we speculate that the effects of BR could also differ between gastric juice and mucosal samples.…”

“…Our results were inconsistent with previous studies that showed no difference in the beta diversity in the gastric mucosal microbiota between patients with and without BR [ 19 , 20 ]. As we discussed the inconsistent results for the effect of H. pylori infection on α-diversity between mucosal samples and gastric juice samples [ 19 , 20 ], we speculate that the effects of BR could also differ between gastric juice and mucosal samples. In addition, the previous study showed significant microbial community differences according to the histology [ 9 ], whereas our study showed no microbial community difference between EGC and LGD.…”

“…However, data on the association between BR and gastric microbiota are often limited, and even if reported, the data were only usually generated from gastric mucosal samples. Indeed, Huang et al reported that chronic gastritis patients with no bile reflux demonstrated a significantly lower microbial richness in mucosal microbiota than those with bile reflux [ 19 ]. In contrast, Yang et al showed no difference in the Chao-1 or Shannon indices regardless of the grades of bile reflux among the mucosal microbiota in patients with chronic gastritis [ 20 ].…”

Alteration of gastric microbiota and transcriptome in a rat with gastric intestinal metaplasia induced by deoxycholic acid

“…The reflux of alkaline bile into the stomach can obviously change the gastric environment and shape the composition of gastric microbiota. For example, Huang et al ( 2022 ) observed 92 patients with CG and found that patients with CAG accompanied by bile reflux had higher microbial diversity and richness than those in non-atrophic gastritis patients without bile reflux (Huang et al, 2022 ). However, our results showed induced richness of gastric microbiota in the GIM rats.…”

Helicobacter pylori-associated Chronic Atrophic Gastritis and Progression of Gastric Carcinogenesis

“…In addition, there is a marked difference in the microbiota structure between patients with and without bile reflux. 59 Excessive methylation can lead to adverse consequences, such as suppressing latent-phase genes, transitioning to the lytic phase, and silencing tumor suppressor genes. In the process, the above factors induce local triggering of the host immune responses and make a difference in lymph node metastasis and the prognosis of EBVaGC.…”