Helicobacter pylori Infection Aggravates Dysbiosis of Gut Microbiome in Children With Gastritis

Abstract

Introduction:Helicobacter pylori infection consistently leads to chronic and low degree of inflammatory response in gastric mucosa and is closely related with gastrointestinal and extra-gastric diseases. Effects of local microbiome in the stomach have been studied in adults and children with H. pylori infection. It is, however, not known whether the intestinal microbial community differs in children with varying H. pylori infection. The aim of this study is to characterize the altered composition of microbiome induced by H. pylori infection and in gastritis. Materials and Methods: This study involved 154 individuals, including 50 children affected by H. pylori-induced gastritis, 42 children with H. pylori-negative gastritis, and 62 healthy controls. Gut microbiome composition was analyzed using 16S rRNA gene-based pyrosequencing. Fecal bacterial diversity and composition were then compared. Results: On the basis of an analysis of similarities and differences, we found that children with H. pylori-induced gastritis exhibited gut bacteria dysbiosis. The ratio of Firmicutes/Bacteroidetes (F:B) at the phylum level had dramatically decreased in H. pylori-positive gastritis group (HPG) and H. pylori-negative gastritis group (HNG), compared with the healthy control group (HCG). At the family and genus levels, relative abundance of Bacteroidaceae and Enterobacteriaceae was prevalent in HPG and HNG, whereas relative abundance of Lachnospiraceae, Bifidobacteriaceae, and Lactobacillaceae was seen in HCG. Prevalence of different taxa of gut microbiome at the class, order, family, and genus levels was also observed among the three groups. Conclusions: Gastritis can cause changes in composition of fecal microbiome, which is exacerbated by H. pylori infection. These changes in gut microbiome may be related to drug resistance and development of chronic gastrointestinal diseases.

Keywords: Helicobacter pylori; children; gastritis; gut microbiome; infection.

Figure 1

Flowchart of this study. 210 children with dyspeptic symptoms and 64 healthy children were initially screened for the study. Ninety-five individuals refused to donate fecal samples, and another 15 children had oral drug history. They all had been excluded. In the second part of the tests, five patients refused to continue all the tests, and another three patients with the gastrointestinal ulcers and/or bleeding were missed. In the healthy children group, one fecal specimen of the child was missing, and another child with oral drug history was ruled out.

Figure 2

Comparison of alpha diversity (A, Shannon index; and B, ACE index) based on the OTU profile. HPG, HNG, and HCG are colored in red, blue, and green, respectively. The P-value was calculated by the Wilcoxon rank-sum test. HPG, Helicobacter pylori-induced gastritis group; HNG, H. pylori-negative gastritis group; HCG, healthy control group; OUT, operational taxonomic unit.

Figure 3

PCoA of bacterial beta diversity based on the unweighted UniFrac distance. (A) Between HPG and HNG. (B) Between HNG and HCG. (C) Between HPG and HCG. PCoA, principal coordinate analysis; HPG, Helicobacter pylori-induced gastritis group; HNG, H. pylori-negative gastritis group; HCG, healthy control group.

Figure 4

Comparison of relative taxa abundance between HPG, HNG, and HCG. (A) Comparison of relative taxa abundance among HPG, HNG, and HCG at the phylum level. (B) Comparison of relative taxa abundance among HPG, HNG, and HCG at the genus level. (C) Venn diagram. HPG, Helicobacter pylori-induced gastritis group; HNG, H. pylori-negative gastritis group; HCG, healthy control group.

Figure 5

Characteristics of microbial community composition in HPG, HNG, and HCG. (A) The most differentially abundant taxa between HPG and HNG (LDA score above 2), which was generated from LEfSe analysis. (B) The enriched taxa of fecal microbiome in HPG and HNG are represented in the cladogram. The central point represents the root of the tree (bacteria), and each ring represents the next lower taxonomic level (phylum to genus: p, phylum; c, class; o, order; f, family; g, genus). (C) The most differentially abundant taxa between HNG and HCG (LDA score above 2), which was generated from LEfSe analysis. (D) The most differentially abundant taxa between HPG and HCG (LDA score above 2), which was generated from LEfSe analysis. (E) Enriched taxa of fecal microbiome in HNG and HCG are represented in cladogram. The central point represents the root of the tree (bacteria), and each ring represents the next lower taxonomic level (phylum to genus: p, phylum; c, class; o, order; f, family; g, genus). (F) The enriched taxa of fecal microbiome in HPG and HCG are represented in cladogram. The central point represents the root of the tree (bacteria), and each ring represents the next lower taxonomic level (phylum to genus: p, phylum; c, class; o, order; f, family; g, genus). (G–K) Relative abundances of five bacteria (Bacteroidaceae, Enterobacteriaceae, Bifidobacteriaceae, Lactobacillaceae, and Lachnospiraceae) among HPG, HNG, and HCG were compared. HPG, Helicobacter pylori-induced gastritis group; HNG, H. pylori-negative gastritis group; HCG, healthy control group; LDA, linear discriminant analysis; LEfSe, linear discriminant effect size.

Figure 6

Predicted metagenome function based on KEGG pathway analysis. Extended error bar plots show the significantly different abundance of KEGG pathways. (A) Between HPG and HNG. (B) Between HNG and HCG. (C) Between HPG and HCG. The proportion (left side) indicates the possible abundance of microbes possessing each functional feature and the difference between proportions for each feature. Circles (right side) represent the difference between the mean proportion of bacteria (the effect size), adjacent to their respective CI (error bars). KEGG, Kyoto Encyclopedia of Genes and Genomes; HPG, Helicobacter pylori-induced gastritis group; HNG, H. pylori-negative gastritis group; HCG, healthy control group.