Topical application of Porphyromonas gingivalis into the gingival pocket in mice leads to chronic‑active infection, periodontitis and systemic inflammation

Abstract

Porphyromonas gingivalis (Pg) , one of the 'red-complex' perio-pathogens known to play a critical role in the development of periodontitis, has been used in various animal models to mimic human bacteria-induced periodontitis. In order to achieve a more realistic animal model of human Pg infection, the present study investigated whether repeated small-volume topical applications of Pg directly into the gingival pocket can induce local infection, including periodontitis and systemic vascular inflammation in wild-type mice. Freshly cultured Pg was topically applied directly into the gingival pocket of the second molars for 5 weeks (3 times/week). After the final application, the mice were left in cages for 4 or 8 weeks and sacrificed. The status of Pg colony formation in the pocket, gingival inflammation, alveolar bone loss, the expression levels of pro-inflammatory cytokines in the serum and aorta, the presence of anti- Pg lipopolysaccharide (LPS) and gingipain (Kpg and RgpB) antibodies in the serum, as well as the accumulation of Pg LPS and gingipain aggregates in the gingiva and arterial wall were evaluated. The topical application of Pg into the gingival pocket induced the following local and systemic pathohistological changes in mice when examined at 4 or 8 weeks after the final topical Pg application: Pg colonization in the majority of gingival pockets; increased gingival pocket depths; gingival inflammation indicated by the increased expression of TNF-α, IL-6 and IL-1β; significant loss of alveolar bone at the sites of topical Pg application; and increased levels of pro-inflammatory cytokines, such as TNF-α, IL-1β, IL-17, IL-13, KC and IFN-γ in the serum in comparison to those from mice receiving PBS. In addition, the Pg application/colonization model induced anti- Pg LPS and gingipain antibodies in serum, as well as the accumulation of Pg LPS and gingipain aggregates in the gingivae and arterial walls. To the best of our knowledge, this mouse model represents the first example of creating a more sustained local infection in the gingival tissues of wild-type mice and may prove to be useful for the investigation of the more natural and complete pathogenesis of the bacteria in the development of local oral and systemic diseases, such as atherosclerosis. It may also be useful for the determination of a treatment/prevention/efficacy model associated with Pg -induced colonization periodontitis in mice.

The interplay between oral microbiota, gut microbiota and systematic diseases

“…P. gingivalis could be detected in the oral cavity of mice 7 days after P. gingivalis inoculation [ 35 ]. Four weeks and 8 weeks after stopping P. gingivalis topical application in the gingiva of mice, P. gingivalis DNA could still be detected in the oral cavity, suggesting that P. gingivalis can colonize and proliferate in mouse gingiva [ 36 ]. P. gingivalis inoculation in oral cavities of mice leads to elevation of the total cultivatable commensal bacterial load and changes the qualitative composition of oral microbiota [ 35 ], increases oral microbial diversity and allows the colonization of potential opportunistic species [ 37 ].…”

hTERT Peptide Fragment GV1001 Prevents the Development of Porphyromonas gingivalis-Induced Periodontal Disease and Systemic Disorders in ApoE-Deficient Mice

“…In a previous study, we conducted an experiment where we topically applied Porphyromonas gingivalis ( Pg ), an anaerobic Gram-negative bacterium and one of the ‘red-complex’ of periodontal pathogens, into the gingival pockets of wild-type (wt) mice. This led to the development of periodontal disease and resulted in both systemic and vascular inflammation [ 24 ]. Pg releases various bacterial toxins, including lipopolysaccharide (LPS), gingipains, and fimbriae, through local secretion and incorporation into complex outer-membrane vesicles (OMVs) [ 25 , 26 , 27 ].…”

“…Our previous findings demonstrated that the local gingival delivery of Pg LPS induced periodontitis and alveolar bone loss in Apolipoprotein E ( ApoE)- deficient mice, accompanied by elevated levels of local and systemic proinflammatory cytokines [ 22 , 24 , 30 ]. Pg gingipains, cysteine endo-proteases, exert virulent effects by degrading the extracellular matrix, cleaving numerous anti-bacterial proteins in saliva, and provoking systemic inflammation [ 31 ].…”

GV1001 Inhibits the Severity of the Ligature-Induced Periodontitis and the Vascular Lipid Deposition Associated with the Periodontitis in Mice

“…We previously reported that ligature-induced periodontitis exacerbates atherosclerosis in Apolipoprotein E ( ApoE )-deficient mice [ 14 , 15 , 16 ] and also found that hyperlipidemia is required for the development and progression of atherosclerosis in mice with ligature-induced periodontitis [ 15 , 16 , 17 ].…”