Duodenal microbiota profiling and its effects on gastrointestinal tract dysfunction

Background Duodenal microbiota has been proposed to be associated with gastrointestinal dysfunction, but population-based data are sparse. Profiling duodenal microbiota using 16S rRNA approach would appear to be a powerful tool for better understanding its role in gastrointestinal manifestations. Methods In a population-based cross-sectional study, 265 adult subjects chosen randomly underwent symptom assessment, upper endoscopy, and gastroduodenal biopsies, with collection of duodenal brushing specimens. The 16S rRNA gene (V3-V4 region) sequencing was conducted using Illumina © MiSeq platform. The microbiome taxonomy was constructed and classified to identify the microbiota composition. The diversity and composition were compared among subjects categorized based on gastrointestinal dysfunction, histopathological features, and demographic characteristics. Results The five most abundant genera in individuals with a normal duodenum were Streptococcus (33%), Veillonella (12%), Prevotella (11%), Rothia (5%) , and Actinomyces (5%). Alpha diversity metrics showed that there were no significant differences among the participants with different demographic or histopathological features. However, the beta diversity of the duodenal microbiota differed significantly between current smokers and non-smokers, and across education level, BMI, as well as age groups. Furthermore, alteration of duodenal microbiota diversity was strongly associated with the presence of non- H. pylori gastritis or the co-occurrence of gastroesophageal reflux and functional dyspepsia based on Adonis R² (PERMANOVA) test ( P < 0.05). Differential abundance of duodenal microbiota composition analysis at genus level illustrated that known pathogens and commensal bacteria, such as Sphingomonas, Lactobacillus , Streptococcus, Sphingomonas, Neisseria , Veillonella , Staphylococcus, Haemophilus , Gemellacea , and Intrasporangiaceae , were related to different histopathological manifestations. Conclusion Alterations of duodenal microbiota signatures are linked to smoking, aging, BMI, education and gastroduodenal disorders. Further mechanistic studies are warranted to further explore the potential effects of duodenal microbiota on gastrointestinal health.