The Effects of Helicobacter pylori Infection on Gastric Microbiota in Children With Duodenal Ulcer

Abstract

Background: Helicobacter pylori (H. pylori) infection is the main cause of chronic gastritis and duodenal ulcer in children. Little is known about the effect of H. pylori on gastric microbiota in children with duodenal ulcer. This study is aimed at the characteristics of gastric microbiota in children with duodenal ulcer on H. pylori infection.

Methods: We studied 23 children diagnosed with duodenal ulcer by gastric endoscopy because of the gastrointestinal symptoms, 15 children were diagnosed with H. pylori infection, while 8 children were without H. pylori infection. Endoscopic mucosal biopsy samples were obtained for DNA extraction. Microbiomes were analyzed by 16S rRNA profiling and microbial functions were predicted using the software Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt).

Results: Bacterial richness and diversity of gastric microbiota in duodenal ulcer with H. pylori-positive were lower than those negative. The gastric microbiota in H. pylori-positive group significantly reduced proportions of six phyla and fifteen genera; only Helicobacter taxa were more abundant in H. pylori-positive group. Co-expression network analysis showed a more complex network of interactions in the H. pylori-positive group than that in the H. pylori-negative group. For the predicted functions, lower abundance in the pathways of carbohydrate metabolism, signal transduction, amino acid metabolism, and lipid metabolism were found in H. pylori-positive group than the H. pylori-negative group. H. pylori colonization reduces a microbial community with genotoxic potential in the gastric mucosa of children with duodenal ulcer.

Conclusions: The presence of H. pylori significantly influences gastric microbiota and results in a lower abundance of multiple taxonomic levels in children with duodenal ulcer. Children with duodenal ulcer exhibit a dysbiotic microbial community with genotoxic potential, which is distinct from that of children with H. pylori infection.

Clinical trial registration: [http://www.chictr.org.cn], identifier [ChiCTR1800015190].

Keywords: 16S rRNA; Helicobacter pylori; children; duodenal ulcer; gastric microbiota.

FIGURE 1

The richness and diversity of the gastric microbiotain children with duodenal ulcer between the H. pylori-positive group and the H. pylori negative group. Good’s coverage (A), Chao1 (B), ACE (C), Shanon (D), Simpson (E), and Heip evenness (F) were used to evaluate the overall structure of the gastric microbiota in the two stomach microtas. ns: P > 0.05; *P < 0.05. Hp+, H. pylori-positive group; Hp-, H. pylori-negative group.

FIGURE 2

Plots of principal coordinate analysis (PCoA) of the gastric microbiota in the two stomach microbiotas based on the Bray-Curtis distance (A) and Weighted Unifrac distance (B). Hp+, H. pylori-positive group; Hp-, H. pylori-negative group.

FIGURE 3

Relative abundance of gastric microbiota at phyla (A) level and genera (B) level within individual gastric biopsies.

FIGURE 4

The linear discriminant analysis effect size (LEfSe) identifies the taxa with the greatest differences of gastric microbiota abundance in children with duodenal ulcer between H. pylori positive group and H. pylori negative group. (A) Cladogram of taxonomic distribution in different levels between the two groups. (B) The histogram of the linear discriminant analysis (LDA) scores in significantly differential bacteria between the two groups. Hp+, H. pylori-positive group; Hp-, H. pylori-negative group.

FIGURE 5

Correlation strengths of the abundant gastric microbiota in different stomach microhabitats from children with duodenal ulcer. Correlation network of the abundant gastric microbiota in H. pylori-positive group (A) and H. pylori-negative group (B). The genera were connected (Gray: positive correlation; Green: negative correlation) when the pair-wise correlation values were significant (P < 0.05) after adjusting the P-values for multiple comparisons. Furthermore, sub-community detection was performed by placing the genera in the same sub-community (represented by the color of nodes) when many links were found at correlation values > 0.6 between members of the subcommunity.

FIGURE 6

Statistical Analysis of Metagenomics Profiles (STAMP) was used to analyze the different bacterial functions between H. pylori positive group and H. pylori negative group at the Kyoto Encyclopedia of Genes and Genome (KEGG) level 2. Hp+, H. pylori positive group; Hp-, H. pylori negative group.

FIGURE 7

The H. pylori-negative group microbiota is characterized by nitrosating bacteria. Functional classification of the predicted metagenome content of the microbiota of H. pylori-positive group and H. pylori-negative group using (A) COG and (B) KO. The normalized relative frequency of nitrate reductase and nitrite reductase in patients with H. pylori-positive group and H. pylori-negative group are shown. Significance was considered for adjusted P < 0.05. COG, Clusters of Orthologous Groups; KO, Kyoto Encyclopedia of Genes and Genome orthology; Hp+, H. pylori positive group; Hp-, H. pylori negative group.