Evaluation of the Gastric Microbiome in Patients with Chronic Superficial Gastritis and Intestinal Metaplasia

Objective To evaluate the gastric microbiome in patients with chronic superficial gastritis(CSG)and intestinal metaplasia(IM)and investigate the influence of Helicobacter pylori(H.pylori)on the gastric microbiome.Methods Gastric mucosa tissue samples were collected from 54 patients with CSG and IM,and the patients were classified into the following four groups based on the state of H.pylori infection and histology:H.pylori-negative CSG(n=24),H.pylori-positive CSG(n=14),H.pylori-negative IM(n=11),and H.pylori-positive IM(n=5).The gastric microbiome was analyzed by 16S rRNA gene sequencing.Results H.pylori strongly influenced the bacterial abundance and diversity regardless of CSG and IM.In H.pylori-positive subjects,the bacterial abundance and diversity were significantly lower than in H.pylori-negative subjects.The H.pylori-negative groups had similar bacterial composition and bacterial abundance.The H.pylori-positive groups also had similar bacterial composition but different bacterial relative abundance.The relative abundance of Neisseria,Streptococcus,Rothia,and Veillonella were richer in the I-HP group than in G-HP group,especially Neisseria(t=175.1,P<0.001).Conclusions The gastric microbial abundance and diversity are lower in H.pylori-infected patients regardless of CSG and IM.Compared to H.pylori-positive CSG group and H.pylori-positive IM,the relative abundance of Neisseria,Streptococcus,Rothia,and Veillonella is higher in H.pylori-positive patients with IM than in H.pylori-positive patients with CSG,especially Neisseria.

Evaluation of polygenic risk score for risk prediction of gastric cancer

Genetic variations are associated with individual susceptibility to gastric cancer.Recently,polygenic risk score(PRS)models have been established based on genetic variants to predict the risk of gastric cancer.To assess the accuracy of current PRS models in the risk prediction,a systematic review was conducted.A total of eight eligible studies consisted of 544842 participants were included for evaluation of the performance of PRS models.The overall accuracy was moderate with Area under the curve values ranging from 0.5600 to 0.7823.Incorporation of epidemiological factors or Helicobacter pylori(H.pylori)status increased the accuracy for risk prediction,while selection of single nucleotide polymorphism(SNP)and number of SNPs appeared to have little impact on the model performance.To further improve the accuracy of PRS models for risk prediction of gastric cancer,we summarized the association between gastric cancer risk and H.pylori genomic variations,cancer associated bacteria members in the gastric microbiome,discussed the potentials for performance improvement of PRS models with these microbial factors.Future studies on comprehensive PRS models established with human SNPs,epidemiological factors and microbial factors are indicated.