Evidence suggests that
periodontitis contributes to the pathogenesis of
inflammatory bowel disease, including
Crohn's disease and
ulcerative colitis. However, few studies have examined the role of swallowing and saliva in the pathogenesis of
gastrointestinal diseases. Saliva contains an enormous number of oral bacteria and is swallowed directly into the intestine. Here, we explored the influence of
periodontitis salivary microbiota on colonic
inflammation and possible mechanisms in
dextran sulfate sodium (DSS)-induced
colitis. The salivary microbiota was collected from healthy individuals and those with
periodontitis and gavaged to C57BL/6 mice.
Periodontitis colitis was induced by DSS for 5 d and
ligature for 1 wk. The degree of colon
inflammation was evaluated through
hematoxylin and
eosin staining, ELISA, and quantitative real-time polymerase chain reaction. Immune parameters were measured with quantitative real-time polymerase chain reaction, flow cytometry, and immunofluorescence. The gut microbiota and metabolome analyses were performed via
16S rRNA gene sequencing and liquid chromatography-mass spectrometry. Although no significant
colitis-associated phenotypic changes were found under physiologic conditions,
periodontitis salivary microbiota exacerbated
colitis in a
periodontitis colitis model after DSS induction. The immune response more closely resembled the pathology of
ulcerative colitis, including aggravated macrophage M2 polarization and Th2 cell induction (T helper 2).
Inflammatory bowel disease-associated microbiota, such as Blautia, Helicobacter, and Ruminococcus, were changed in DSS-induced
colitis after
periodontitis salivary microbiota gavage.
Periodontitis salivary microbiota decreased
unsaturated fatty acid levels and increased
arachidonic acid metabolism in DSS-induced
colitis, which was positively correlated with Aerococcus and Ruminococcus, suggesting the key role of these metabolic events and microbes in the exacerbating effect of
periodontitis salivary microbiota on experimental
colitis. Our study demonstrated that
periodontitis contributes to the pathogenesis of
colitis through the swallowing of salivary microbiota, confirming the role of
periodontitis in systemic disease and providing new insights into the etiology of gastrointestinal inflammatory diseases.