Prevalence of periodontal pathogens in subgingival lesions, atherosclerotic plaques and healthy blood vessels: a preliminary study

BACKGROUND AND OBJECTIVE

Previous studies have reported different periodontal bacteria in atherosclerotic lesions, but their involvement in plaque formation remains unclear. The aim of the present study was to investigate the presence of 20 periodontal bacteria in atherosclerotic samples and healthy blood vessels (used as controls) and to clarify their relationship in regard to clinical and bacteriological periodontal status.

MATERIAL AND METHODS

The day before vascular surgery the patients had a thorough periodontal examination and bacteriological samples were taken from periodontally diseased sites. Atheromatous plaques, internal mammary arteries and saphenous veins were harvested during surgery. A DNA-DNA hybridization procedure was used to screen periodontal and vascular samples for the 20 selected bacterial species.

RESULTS

Periodontal samples from the severe periodontitis group were found to have a higher prevalence and biomass of bacterial species than the moderate periodontitis group. In vessel samples, the prevalence of the same 20 bacterial species analyzed together was similar in the two groups, except for saphenous veins.

CONCLUSION

The presence of periodontal pathogens in atherosclerotic plaques and in apparently healthy vessels appeared to reflect a higher level of bacteremia rather than infection of endothelial cells.

Expression of matrix metalloproteinases in healthy and diseased human gingiva

BACKGROUND, AIMS

The aim of our study was to investigate the patterns of several metalloproteinases (MMP-1, MMP-2 and MT1-MMP) mRNAs expression using a semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and to correlate them with clinical parameters and bacteriological diagnosis in healthy versus diseased human gingiva.

METHODS

To identify the cell origin of MMP production, in situ hybridization (ISH) was also performed for the MMPs on the same samples. 17 gingival biopsies were collected (13 affected by advanced periodontitis and 4 healthy used as controls) and plaque index, gingival index, pocket depth and bleeding on probing were measured. Subgingival microbial samples were also collected to be analysed by a DNA probe technique. The biopsies were processed both for RT-PCR and ISH. We also investigated a model for bacterial induced MMP expression in human gingival fibroblasts (HGF) infected by Eikenella corrodens.

RESULTS

We found an expression of the mRNA encoding MMP-1 only in diseased gingiva but at low levels relative to beta-actin (mean+/-SD: diseased versus healthy: 0.013+/-0.024 versus 0). Although the frequencies and levels of mRNA encoding for MMP-2 or MT1-MMP are not significantly different between each group (mean+/-SD: 0.329+/-0.344 versus 0.137+/-0.219 for MMP-2; 0.485+/-0.374 versus 0.466+/-0.296 for MT1-MMP), using ISH, we observed an expression of both mRNAs in fibroblasts of pathological specimens at sites that histologically showed signs of chronic inflammation and connective tissue remodelling. In vitro infection of HGF by Eikenella corrodens stimulated 3-fold the production of the mRNA encoding MMP-2 while other mRNAs remained unchanged.

CONCLUSION

Our results did not reveal significant differences in the expression of mRNAs encoding for the MMPs between healthy and periodontitis-affected patients, reflecting the great heterogeneity in the periodontal status of individuals. However, they indicate that gingival fibroblasts are an active source of MMP-2 production in response to a periopathogen.