In Vitro Models of Tissue Penetration and Destruction by Porphyromonas gingivalis

Abstract

Porphyromonas gingivalis is a gram-negative anaerobic bacterium that is considered the key etiologic agent of chronic periodontitis. Arg-and Lys-gingipain cysteine proteinases produced by P. gingivalis are key virulence factors and are believed to be essential for significant tissue component degradation, leading to host tissue invasion by periodontopathogens. Two in vitro models were used to determine the extent to which P. gingivalis can reach connective tissue. The tissue penetration potential of P. gingivalis was first investigated by using an engineered human oral mucosa model composed of normal human epithelial cells and fibroblasts. Internalized bacteria were assessed by transmission electron microscopy. Bacteria were observed within multilayered gingival epithelial cells and in the space between the stratified epithelium and the lamina propria. A gingipainnull mutant strain of P. gingivalis was found to be less potent in penetrating tissue than the wild-type strain. Proinflammatory responses to P. gingivalis infection were evaluated. P. gingivalis increased the secretion of interleukin-1␤, interleukin-6, interleukin-8, and tumor necrosis factor alpha. In the second part of the study, the contribution of P. gingivalis gingipains to tissue penetration was investigated by using a reconstituted basement membrane model (Matrigel). The penetration of 14 C-labeled P. gingivalis cells through Matrigel was significantly reduced when leupeptin, a specific inhibitor of Arg-gingipain activity, was added or when a gingipain-null mutant was used. The results obtained with these two relevant models support the capacities of P. gingivalis to infiltrate periodontal tissue and to modulate the proinflammatory response and suggest a critical role of gingipains in tissue destruction.

Effects of egg yolk antibody against Porphyromonas gingivalis gingipains in periodontitis patients

“…Although it has been reported that gingival epithelial cells act as a physical barrier against the entry of periodontopathic bacteria, P. gingivalis can pass through the epithelial barrier (16,40). Previous reports have suggested that the proteolytic activities of gingipains affect epithelial cells by loosening the epithelial tissue from the basement membrane (41). These observations suggest that gingipains are the most promising target for vaccination against periodontitis and related systemic diseases.…”

Construction and characterization of a multilayered gingival keratinocyte culture model: the TURK-U model

“…First in house multilayer models were constructed on permeable membranes at an air-liquid interface (Breitkreutz et al 1984;Rosdy and Clauss 1990). These models were successfully used to test invasive characteristics of oral bacteria and Candida species (Andrian et al 2004;Yadev et al 2011). A gingival epithelium model was later developed with the implementation of gingival fibroblast embedded collagen layer and dental tissue components into keratinocyte multilayer models (Oksanen and Hormia 2002).…”

The prevalence rate of Porphyromonas gingivalis and its association with cancer: A systematic review and meta-analysis

“…Some carcinogenic properties of P. gingivalis are as follows: it attaches to different lines of gingival cancer cells; 28 invades the epithelial cells of gingiva in experimental conditions; 29 it prevents and restrains apoptosis of epithelial cells; 30 it proliferates and survives in the epithelial cells and spreads to other cells; 31 it promotes cell survival and increases cellular proliferation; 32 it induces COX-2 gene expression; 33 and it increases the production of TNF-a, IL-6, IL-8, and IL-1b. 34 P. gingivalis possesses a lipoprotein and LPS on its external surface that can provoke proliferation of human fibroblast cells. 35 Evidences show that micro-RNA (miRNA) has an important role in the incidence of cancer.…”