Bacterial extracellular vesicles in the oral-gut axis: Roles in periodontitis and inflammatory bowel disease.

The oral-gut axis links the oral and gut microbiomes, both anatomically and functionally, and its dysregulation is implicated in periodontitis and inflammatory bowel disease (IBD). Bacterial extracellular vesicles (BEVs), nano-sized particles (20-250 nm) released by diverse microbes, serve as key mediators of inter-organismal communication along this axis. Carrying virulence factors, nucleic acids, and immunomodulators, BEVs influence microbial ecology and host immunity. In the oral cavity, pathogen-derived BEVs (e.g., from Porphyromonas gingivalis) promote biofilm formation, immune evasion, and tissue destruction. In the gut, BEVs from commensals (e.g., Akkermansia muciniphila) reinforce barrier function and suppress inflammation, whereas those from pathogens exacerbate dysbiosis. Critically, BEVs mediate bidirectional crosstalk: oral pathogen BEVs can translocate to the gut and worsen IBD, while beneficial gut-derived BEVs may attenuate periodontal inflammation. This review summarizes the roles of BEVs in oral-gut communication, their involvement in inflammatory disease pathogenesis, and their potential as biomarkers and therapeutics.