Oral–Gut Microbiome Axis in Gastrointestinal Disease and Cancer

Abstract

It is well-known that microbiota dysbiosis is closely associated with numerous diseases in the human body. The oral cavity and gut are the two largest microbial habitats, playing a major role in microbiome-associated diseases. Even though the oral cavity and gut are continuous regions connected through the gastrointestinal tract, the oral and gut microbiome profiles are well-segregated due to the oral–gut barrier. However, the oral microbiota can translocate to the intestinal mucosa in conditions of the oral–gut barrier dysfunction. Inversely, the gut-to-oral microbial transmission occurs as well in inter- and intrapersonal manners. Recently, it has been reported that oral and gut microbiomes interdependently regulate physiological functions and pathological processes. Oral-to-gut and gut-to-oral microbial transmissions can shape and/or reshape the microbial ecosystem in both habitats, eventually modulating pathogenesis of disease. However, the oral–gut microbial interaction in pathogenesis has been underappreciated to date. Here, we will highlight the oral–gut microbiome crosstalk and its implications in the pathogenesis of the gastrointestinal disease and cancer. Better understanding the role of the oral–gut microbiome axis in pathogenesis will be advantageous for precise diagnosis/prognosis and effective treatment.

Analysis of oral microbiota alterations induced by Helicobacter pylori infection and vonoprazan‐amoxicillin dual therapy for Helicobacter pylori eradication

“…Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria are the most abundant bacteria at the phylum level, and Fusobacterium, Haemophilus, Neisseria, Prevotella, and Streptococcus are abundant at the genus level in the oral microbiota in healthy individuals. 24,25 The composition structure of H. pylori-positive and H. pylorinegative patients at the phylum and genus levels was different in our study. Significant differences in taxa were also observed between the two groups using LEfSe.…”

Oral pathogen in the pathogenesis of colorectal cancer

“…61 Specific bacteria can colonize in the distal gut of germ-free mice by fecal transplant gavage, showing the feasibility of oral bacteria transmission through the digestive tract and colonizing in colorectum. 62 However, the oral bacteria needs to overcome the oral-gut barrier, 63 including gastric acid, bile acid, and colonization of gut commensal microbiota. 64 During the application of proton pump inhibitor and antibiotics, the impaired barrier facilitated the translocation of oral microbes, which leads the increasing colonization of specific oral pathogens in the gut and mediates the occurrence and development of intestinal diseases.…”

Oral and fecal microbiota in patients with diarrheal irritable bowel syndrome

“…Furthermore, this study discovered some similarities between the oral microbiota and fecal microbiome of IBS-D patients. There may be crosstalk between oral and gut microbiota (Oral-Gut Microbiota Axis) which can synergistically participate in the pathogenesis of gastrointestinal diseases [40]. It is a worthwhile research direction to investigate the pathogenesis of IBS-D from the standpoint of the Oral-Gut Microbiota axis.…”