Diversity of the gastric microbiota in the Helicobacter pyloriinfected and non-infected patients and its link to transcriptional changesof gene mediators in the NF-κB inflammatory pathway among patientswith chronic gastritis

Background and Aim : The role of gastritis, as a serious disease, in the formation of gastric cancerand its interplay with microbial infections remains largely unknown. We aimed to investigatediversity of bacterial communities and their links with alteration in transcriptional levels of genesassociated with the NF-κB inflammatory pathway in the gastric tissue.Methods : Gastric biopsy samples of ۱۶۸ patients with gastric disorders were provided.Histological examination of the biopsies and their culture on specific and general culture mediawere done to show histological changes and isolation of Helicobacter and non-Helicobacterbacteria, respectively. Among the patients with moderate chronic gastritis, ۱۶S rRNA genesequencing were done on a healthy individual, ۸ H. pylori infected and ۵ H. pylori non-infectedpatients. Discriminative indicator bacteria, alpha and beta diversity of the characterized bacterialtaxa in each group of the patients and their correlations with relative expression values of NF-κBpathway were evaluated.Results : These results showed significant microbiome diversity between the patients with H.pylori infection compared with non-infected patients. The enrichment of members of the oralmicrobiota in H. pylori-negative patients was seen in the studied cases. Epsilonbacteraeota in H.pylori-infected and Firmicutes in the non-infected patients were the most prevalent phyla. LEfSeanalysis proposed members of Helicobacteraceae and Streptococcaceae as main indicatororganisms in the H. pylori-positive and H. pylori-negative patients, respectively. It seems that theinteraction between the characterized gastric microbes and the expression levels of inflammatoryand carcinogenic genes is complex.Conclusion : Our results showed colonization of the stomach by a variety of bacterial taxa inpatients with moderate chronic gastritis. Although members of the microbiota from the oral cavityand upper respiratory tract were detected as common bacteria associated with gastritis in the H.pylori-negative patients, establishment of their role as true pathogens or a bystander and their linkswith induction of inflammatory response need further studies.

کلیدواژه ها:

Helicobacter pylori ، Microbiota ، Gastritis ، NF-κB pathway ، ۱۶S rDNA