Porphyromonas gingivalis invades oral epithelial cells in vitro

Porphyromonas gingivalis invasion of gingival epithelial cells

Porphyromonas gingivalis, a periodontal pathogen, can invade primary cultures of gingival epithelial cells. Optimal invasion occurred at a relatively low multiplicity of infection (i.e., 100) and demonstrated saturation at a higher multiplicity of infection. Following the lag phase, during which bacteria invaded poorly, invasion was independent of growth phase. P. gingivalis was capable of replicating within the epithelial cells. Invasion was an active process requiring both bacterial and epithelial cell energy production. Invasion was sensitive to inhibitors of microfilaments and microtubules, demonstrating that epithelial cell cytoskeletal rearrangements are involved in bacterial entry. P. gingivalis, but not epithelial cell, protein synthesis was necessary for invasion. Invasion within the epithelial cells was not blocked by inhibitors of protein kinase activity. Invasion was inhibited by protease inhibitors, suggesting that P. gingivalis proteases may be involved in the invasion process. Low-passage clinical isolates of P. gingivalis invaded with higher efficiency than the type strain. Serum inhibited invasion of the type strain but had no effect on the invasion of a clinical isolate. Invasion of gingival epithelial cells by P. gingivalis may contribute to the pathology of periodontal diseases.

Cross-reactivity between human sialyl Lewis(x) oligosaccharide and common causative oral bacteria of infective endocarditis

The expression of sialy-Lewis(x) (sLe(x); Neu5Ac alpha 2-3 Gal beta 1-4) (Fuc alpha 1-3) GlcNAc-R) on oral bacteria producing infective endocarditis was determined by a whole-cell enzyme linked immunosorbent assay and an immunoelectron microscopy using the well-characterized anti-sLe(x) monoclonal antibody SNH-3 (mAb SNH-3; IgM class). mAb SNH-3 reacted strongly with whole cells of oral bacteria: Streptococcus sanguis, Streptococcus mutans, Streptococcus mitis, Streptococcus salivarius, Streptococcus intermedius, Streptococcus constellatus, Streptococcus anginosus, Streptococcus pyogenes, Actinobacillus actinomycetemcomitans, Eikenella corrodens and Porphyromonas gingivalis. The negatively stained immuno-electron micrograph of Streptococcus pyogenes showed many reactive gold particles on the cell surface. Our findings demonstrated the existence of immunologic mimicry between the sLe(x) oligosaccharide and cell surface antigens of many species associated with infective endocarditis. We propose the hypothesis that if these bacteria escape their normal habitats, the surface components that mimic the sLe(x) oligosaccharide might bind to host antigens of the selectin family which could promote binding to endothelial cells and, consequently, initiation of the events leading to infective endocarditis.

Pathogenic strategies of the oral anaerobe, Porphyromonas gingivalis

Adult periodontitis is a chronic inflammatory disease that affects over 49 million people in the USA alone. Porphyromonas (formerly Bacteroides) gingivalis, a Gram-negative anaerobe, has a diverse repertoire of virulence factors that may be involved in the induction or progression of periodontitis.

Host-related genotypic heterogeneity of Porphyromonas gingivalis strains in the beagle dog

The present investigation explored the genotypic heterogeneity of Porphyromonas gingivalis using restriction endonuclease analysis and ribotyping of 64 P. gingivalis isolates, recovered from the periodontal pockets of 3 beagle dogs, 2 of which were reared together. The isolates originated from both healthy and periodontal disease affected sites and thereby enabled the study of bacterial genotype with respect to (i) individual host, (ii) ecological niche (site within host) and (iii) level of periodontal health. Whole genomic DNA was extracted from each isolate and digested by the restriction endonuclease KpnI. Digestion fragments were separated by electrophoresis and transferred onto nylon membranes. The blots were hybridized with a digoxigenin-labeled 16S rDNA probe, and hybridization bands were detected using an anti-digoxigenin antibody conjugated with alkaline phosphatase and enhanced chemiluminescence. Fourteen genomic fingerprints and 13 ribotypes were observed among the 64 isolates. As many as 8 distinct fingerprints were detected within a single host and up to 4 fingerprints within a single periodontal pocket. The dogs reared together shared 2 common clonal types but also exhibited clonal types unique to each dog. No clear association between clonal type and periodontal health status could be made. The results revealed an extensive intra-host genotypic heterogeneity of P. gingivalis strains in the beagle dog and indicated that ribotyping was a sensitive method for differentiating clonal types within species.

Porphyromonas gingivalis invades human pocket epithelium in vitro

The present study examined the adhesive and invasive potential of Porphyromonas gingivalis interacting with human pocket epithelium in vitro. Pocket epithelial tissue, obtained during periodontal surgery of patients with advanced periodontal disease, generated a stratified epithelium in culture. P. gingivalis strains W50 and FDC 381 (laboratory strains), OMGS 712, 1439, 1738, 1739 and 1743 (clinical isolates) as well as Escherichia coli strain HB101 (non-adhering control) were tested with respect to epithelial adhesion and invasion. Adhesion was quantitated by scintillation spectrometry after incubation of radiolabeled bacteria with epithelial cells. The invasive ability of P. gingivalis was measured by means of an antibiotic protection assay. The epithelial multilayers were infected with the test and control strains and subsequently incubated with an antibiotic mixture (metronidazole 0.1 mg/ml and gentamicin 0.5 mg/ml). The number of internalized bacteria surviving the antibiotic treatment was assessed after plating lyzed epithelial cells on culture media. All tested P. gingivalis strains adhered to and entered pocket epithelial cells. However, considerable variation in their adhesive and invasive potential was observed. E. coli strain HB101 did not adhere or invade. Transmission electron microscopy revealed that internalization of P. gingivalis was preceded by formation of microvilli and coated pits on the epithelial cell surfaces. Intracellular bacteria were most frequently surrounded by endosomal membranes; however, bacteria devoid of such membranes were also seen. Release of outer membrane vesicles (blebs) by internalized P. gingivalis was observed. These results support and extend previous work from this laboratory which demonstrated invasion of a human oral epithelial cell-line (KB) by P. gingivalis.