Implication of Porphyromonas gingivalis in colitis and homeostasis of intestinal epithelium

Abstract

Emerging evidences have reported that periodontitis can be a risk factor for the pathogenesis of various systemic diseases. Porphyromonas gingivalis (Pg), one of the crucial pathogens in chronic periodontitis, has been spotlighted as a potential cause for the promotion and acceleration of periodontitis-associated systemic disorders. To investigate the association between Pg and intestinal disease or homeostasis, we treated Pg-derived lipopolysaccharide (LPS) in murine colitis model or intestinal organoid, respectively. Pg-derived LPS (Pg LPS) was administrated into chemically induced murine colitis model and disease symptoms were monitored compared with the infusion of LPS derived from E. coli (Ec LPS). Organoids isolated and cultured from mouse small intestine were treated with Pg or Ec LPS and further analyzed for the generation and composition of organoids. In vivo observations demonstrated that both Pg and Ec LPS exerted slight protective effects against murine colitis. Pg LPS did not affect the generation and growth of intestinal epithelial organoids. Among subtypes of epithelial cells, markers for stem cells, goblet cells or Paneth cells were changed in response to Pg LPS. Taken together, these results indicate that Pg LPS leads to partial improvement in colitis and that its treatment does not significantly affect the self-organization of intestinal organoids but may regulate the epithelial composition.

Keywords: Colitis; Intestinal epithelium; Organoid; Periodontitis; Porphyromonas gingivalis.

Fig. 1

Monitoring of colitic mice. (a) Body weight loss and lethality of mice were monitored for 12 days. The body weight of each mouse at day 0 was calculated as 100%. Numbers in parentheses mean the percentage of dead mice. In ‘DSS + PBS’ group, 2 mice at day 11 and 1 mouse at day 12 died. In ‘DSS + EcLPS’ and ‘DSS + EcLPS’ group, 1 mouse at day12 died, respectively. (b) Disease activity index indicating colitis severity was scored at day 12. 6 mice per group were used. In (b), p-value significance was calculated by comparing other groups against (+) group (marked as +). **P < 0.01

Fig. 2

Gross and histological evaluation of colon. (a) Colon length was measured from proximal colon to rectum. (b) Destruction of epithelial structure and scattered infiltration of inflammatory cells were assessed as histopathological score in H&E stained section of colon tissues. Results are shown as mean ± SD. Representative areas showing the damaged area with typical structure destruction and leukocyte infiltration (black box) were magnified. In (b), p-value significance was calculated by comparing other groups against (+) group (marked as +). *P < 0.05, **P < 0.01

Fig. 3

Observation of the organoid from mouse small intestine. The organoid was generated from crypt cells of moue small intestine and maintained using conditioned media (a) Photographs of organoids were taken at day 2, 4 and 6 in the presence or absence of LPS. (b) The number of budding was counted on day 5

Fig. 4

Quantification of markers for epithelial cell differentiation. The organoid was harvested at day 5 and selected markers for differentiation of epithelial cells were determined by qPCR. (a) Makers for stem cells and proliferation were measured. (b) Markers for Paneth cells, enterocytes, goblet cells and enteroendocrine cells were determined. Results are shown as mean ± SD. *P < 0.05, **P < 0.01, ***P < 0.001