Bioinformatic evaluation of the potential oral-gut translocation of periodontal pathogens in patients with colorectal polyps

Abstract

Objective: This study aimed to characterize the profiles of the oral and gut microbiota of patients with colorectal polyps using 16S rRNA gene sequencing and bioinformatic approaches. Background: Previous studies have shown microbial translocation from the oral cavity to the gut, implying pathogenic impacts on gastroesophageal disease, including colorectal cancer (CRC). However, its details remain unclear. Methods: Twenty patients scheduled for endoscopic colorectal polypectomy were enrolled in this study. Oral samples (saliva and subgingival dental plaque) and intestinal samples (feces and swab of intestinal mucosa) were collected during preoperative and 6–month–postoperative reassessment periods. After sequencing the V3–V4 region of the bacterial 16S rRNA gene, several bioinformatic analyses (bacterial composition, diversity, core microbiome, and shared ASV) were performed on pre– and postoperative samples for each subject. Results: The bacterial composition was dominated by Bacteroides, Streptococcus, Fusobacterium, Veillonella, and Prevotella_7 in all four samples. Beta diversity analysis using weighted UniFrac distance distinctly segregated the samples between oral and intestinal environments in the principal coordinate analysis plot. Core microbiome analysis revealed that Streptococcus and Porphyromonas were dominantly shared in intra–oral environments. Additionally, alongside Streptococcus, periodontitis–related bacteria, such as Veillonella, Fusobacterium, Porphyromonas, Prevotella_7, Haemophilus, and Prevotella, were identified as shared genera between oral and intestinal environments. Finally, shared ASV analysis demonstrated that Streptococcus was shared in the oral and intestinal environments of most patients, while periodontal pathogens were shared in some patients. Conclusions: The core microbiome and shared ASV analyses revealed that several genes are shared between oral and intestinal environments in patients with colorectal polyps, indicating the oral–gut translocation of periodontitis–related bacteria. Further large–scale studies are needed to elucidate their involvement in CRC.