Key periodontal pathogens may mediate potential pathogenic relationships between periodontitis and crohn's disease

Abstract

Background: Crohn's disease (CD)-associated periodontitis is common. However, the role of periodontal pathogens in the Coexistence of CD and periodontal disease remains unclear.

Methods: To investigate the potential relationship mediated by periodontal pathogens between periodontitis and CD, we collected salivary samples from healthy participants (H group, n = 12), patients with CD (Ch group, n = 10), patients with periodontitis (Ps group, n = 12), and patients with Coexistence of CD and periodontal disease (Cp group, n = 12) and analyzed them by 16 S rRNA sequencing.

Results: Patients with Coexistence of CD and periodontal disease had increased levels of Fusobacterium, Actinomyces, Leptotrichia, and Prevotella, which correlated with the severity of periodontitis. Conversely, the levels of Streptococcus, Neisseria, Haemophilus, and Gemella, which decreased in Coexistence of CD and periodontal disease, were negatively correlated with the severity of periodontitis. To further investigate the role of periodontal pathogens in CD development, representative periodontal pathogens causing periodontitis, Porphyromonas gingivalis and Fusobacterium nucleatum, were administered to mice. These pathogens migrate to, and colonize, the gut, accelerating CD progression and aggravating colitis, and even systemic inflammation. In vitro experiments using a Caco-2/periodontal pathogen coculture revealed that P. gingivalis and F. nucleatum increased intestinal permeability by directly disrupting the tight junctions of intestinal epithelial cells.

Conclusion: Our findings strongly suggest that periodontal pathogens play a role in the relationship between periodontitis and CD. These results provide a basis for understanding the pathogenesis of Coexistence of CD and periodontal disease and may lead to the development of novel therapeutic strategies.

Keywords: Fusobacterium nucleatum; Porphyromonas gingivalis; Crohn’s disease; Periodontal pathogens; Periodontitis.

Fig. 1

OTUs and microbial diversity analysis of saliva from patients with CD and/or periodontitis. (A) Venn diagram of the common and specific OTUs in saliva. (B) Alpha diversity of Shannon indexes between the sample types. (C) Least-squares discriminant analysis (PLS-DA) of UniFrac distances based on OTU composition and abundances. (D) Weighted UniFrac distance of β diversity. Cp, patients with CD and periodontitis; Ch, patients with CD; Ps, patients with periodontitis; H, healthy individuals; OTUs, operational taxonomic units; CD, Crohn’s disease

Fig. 2

Microbial composition of saliva from patients with CD and/or periodontitis. (A) Microbial composition across all samples at the phylum level. (B) (C) Microbial composition across samples of Cp, Ch, and H groups at the genus level. (D) Microbial composition across samples of Cp, Ps, and H groups at the genus level. Cp, patients with CD and periodontitis; Ch, patients with CD; Ps, patients with periodontitis; H, healthy individuals; CD, Crohn’s disease

Fig. 3

Correlation between periodontitis index and top ten bacterial genera in the Cp and Ch groups. DMFT, missing or filled permanent teeth; BOP, bleeding on probing; PPD, periodontal pocket depth; CAL, clinical attachment loss; Cp, patients with Crohn’s disease and periodontitis; Ch, patients with Crohn’s disease;

Fig. 4

Periodontal pathogens accelerated the progression of DSS-induced CD in a mouse model. (A) Average content of periodontal pathogens in fecal samples of each group. (B) Weight loss (the day’s body weight/weight on day 0). (C) Disease activity index of CD mice after 7-day periodontal pathogens gavage treatment. (D) Colon length of mice at sacrifice. Pg, Porphyromonas gingivalis; Fn, Fusobacterium nucleatum; CD, Crohn’s disease; DSS, dextran sulfate sodium

Fig. 5

Periodontal pathogens exacerbated intestinal and systemic inflammation. (A) Hematoxylin and eosin staining of colon in each group. (B) Histological score for colitis of each CD sample. Levels of serum inflammatory cytokines IL-1β (C), IL-6 (D), and TNF-α (E) in each group. CD, Crohn’s disease

Fig. 6

Caco-2/periodontal pathogen coculture in vitro. Cellular activity determined using the Cell Counting Kit-8. Immunofluorescence staining of tight junction protein zonula occludens protein 1 (ZO-1, green) in Caco-2 cells