Advances in periodontal diagnosis. 6. Proteolytic and hydrolytic enzymes of inflammatory cell origin

Genetic Susceptibility and Protein Expression of Extracellular Matrix Turnover-Related Genes in Oral Submucous Fibrosis

Betel quid (BQ) chewing increased the risk of oral cancer and oral submucous fibrosis (OSMF), an oral premalignant disorder (OPMD) with malignant transformation potential. BQ components such as areca nut (AN), trauma by coarse AN fiber, catechin, copper, alkaloids, stimulated reactive oxygen species (ROS), inflammation and cytotoxicity are suggested to be the contributing factors. They may induce tissue inflammation, proliferation of fibroblasts and collagen deposition, myofibroblast differentiation and contraction, collagen cross-links and inhibit collagen phagocytosis, finally leading to the development of OSMF and oral cancer. These events are mediated by BQ components-induced changes of extracellular matrix (ECM) turnover via regulation of TGF-β1, plasminogen activator inhibitor-1 (PAI-1), cystatin, lysyl oxidase (LOX) and tissue inhibitors of metalloproteinases (TIMPs) and metalloproteinases (MMPs). Genetic susceptibility is also involved in these disease processes. Further understanding the molecular mechanisms of BQ-induced OSMF and oral cancer can be helpful for future disease prevention and treatment.

The defensive role of lysozyme in human gingiva in inflammatory periodontal disease

BACKGROUND AND OBJECTIVE

The presence of lysozyme in human gingiva has not previously been demonstrated. In this study, we looked for evidence for the potential role of lysozyme as a protector of gingival elastic fibres. The objective of this study was also to determine the ex vivo susceptibility to hydrolysis of gingival elastic fibres from patients with or without periodontal disease by human leukocyte elastase and by human cathepsin G.

MATERIALS AND METHODS

Using gingival tissue sections from eight control, 10 gingivitis and 10 periodontitis patients, we evaluated the area fraction occupied by gingival elastic fibres (after selective staining) by the use of automated image analysis. In the ex vivo experiments, serial tissue sections from four control, four gingivitis, four young periodontitis and four aged periodontitis patients were submitted to the action of human leukocyte elastase and cathepsin G, after which enzymatic activities were determined by image analysis. Indirect immunodetection of lysozyme was also done on tissue sections for all patients included in this study.

RESULTS

Large variations of the area fraction occupied by elastic fibres were observed in human gingiva from young and aged patients with and without periodontal disease. In control and gingivitis patients, leukocyte elastase and cathepsin G had high comparable elastin solubilizing activities. With young and aged periodontitis patients, the two serine proteinases had weak elastin solubilizing activities. Lysozyme appeared to be present at the periphery of gingival elastic fibres in periodontitis patients.

CONCLUSION

Lysozyme can be considered an important natural protector of elastic fibres in pathological gingiva.

Anti-Neutrophil Cytoplasmic Autoantibodies: A Renewed Paradigm in Periodontal Disease Pathogenesis?

In the past, various models including the autoimmunity model have been proposed to explain the pathogenesis of periodontal diseases. The aim of this review is to introduce the pathogenic role of anti-neutrophil cytoplasmic autoantibodies (ANCAs) in various autoimmune diseases and compare these conditions with periodontal disease to elucidate common pathogenic mechanisms. Also, a novel model to explain the pathogenesis of periodontal disease based on the concept of ANCA-associated autoimmunity is proposed. This encompasses a wide array of biochemical mediators that range from direct and indirect initiators of ANCA production and eventual release of proinflammatory mediators and free radicals, all of which have been implicated in periodontal tissue destruction in the past. In addition, specific links between the typical ANCA-associated diseases and periodontal disease are discussed. Finally, a new paradigm in the periodontal disease-associated destruction is proposed that includes the currently accepted mechanism, namely, the genetic-microbial-host interactions.

Analysis of the relationship between the severity of periodontal destruction and proteoglycan metabolism of gingiva and gingival crevicular fluid

BACKGROUND

Although it is well-described that proteoglycans (PGs) are among the major non-collagenous components of the matrix which are degraded during periodontal diseases, the relationship between PG metabolism and seventy of periodontal breakdown, the extent of degradation of PGs together with the resulting end-products, and the elimination pathways of these catabolic end-products is likely to need further clarification.

OBJECTIVE

The main aim of the present study was to analyze the possible impact of severity of periodontal destruction on PG metabolism of gingiva and gingival crevicular fluid (GCF).

MATERIAL AND METHODS

For this purpose, gingiva and GCF samples obtained from patients (n = 45) exhibiting sites (n = 57) with moderate periodontal breakdown (MP) or severe periodontal breakdown (SP) were analyzed for PG metabolism via spectrophotometric determination of uronic acid levels. Gingiva and GCF samples were obtained from the same sites in every patient to analyze the possible relationship between uronic acid content of gingival tissue and GCF.

RESULTS

No significant differences were found in uronic acid levels between sites with MP and SP (p > 0.05). The uronic acid content of GCF and gingiva showed significant overlaps between MP and SP sites and uronic acid levels did not present any constant correlation with the clinical parameters (p > 0.05). In a similar manner, uronic acid content of GCF and gingival tissue was not correlated (p > 0.05).

CONCLUSION

The lack of a significant correlation between the uronic acid content of gingival tissue and GCF may suggest that the passage of PG metabolites from gingiva to GCF is likely to be under the influence of multifactorial interactions rather than being linear. As a general measure of PG metabolism, uronic acid levels do not seem to be related with the severity of periodontal destruction and tend to act as different measures when compared to traditional clinical parameters.

Are cytokines linked to collagen breakdown during periodontal disease progression?

BACKGROUND

Evidence of the role of cytokines produced by resident and inflammatory cells during inflammation is well established. The aim of this study was to quantify in healthy and diseased human gingiva the area fraction (AA%) occupied by collagen fibers and the amount of cytokines such as interleukin (IL)-1beta, IL-4, IL-6, tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, and epidermal growth factor (EGF) to investigate a possible correlation between such cytokines, collagen degradation, and the gingival index.

METHODS

Gingival tissue specimens from 6 healthy controls (group 1), 6 patients with mild gingival inflammation (group 2), 6 patients with moderate gingival inflammation (group 3), and 6 patients with severe gingival inflammation (group 4) were cultured for 72 hours, and the cytokines present in the culture media were quantified using an enzyme-linked immunosorbent assay (ELISA). Paraffin gingival sections from the 24 subjects were stained with sirius red F3Ba for visualization of collagen fibers, then the area fraction (AA%) occupied by the gingival fibers was determined by automated image analysis.

RESULTS

The present study revealed significant differences (P < 0.05) between means of AA% in group 1 (53%), group 2 (41%), group 3 (39.5%), and group 4 (35%) for collagen fibers. Compared to controls, there were significant increases of IL-1beta (groups 3 and 4), IL-6, and TNF-alpha (group 3); a significant decrease of IL-4 (groups 2, 3, and 4) and TGF-beta (groups-2 and, 3); and no change of EGF. The collagen AA% was significantly correlated with the amounts of IL-4 and TGF-beta, and significantly inversely correlated with the amounts of IL-1beta for all 3 inflamed groups and IL-6 and TNF-alpha for groups 2 and 3.

CONCLUSION

The present study showed that EGF was not changed in inflamed gingival tissue and that IL-1beta and IL-4 were particularly and intensively correlated with collagen loss. These 2 cytokines could be markers of clinical severity during active periodontitis.

Is collagen breakdown during periodontitis linked to inflammatory cells and expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases in human gingival tissue?

BACKGROUND

Evidence of the role of matrix metalloproteinases (MMPs) produced by resident and inflammatory cells in periodontal destruction is now well established. The purpose of this study was to quantify, in healthy and diseased upper gingival connective tissue, the area fraction (AA%) occupied by collagen fibers, the cell number belonging to inflammatory cell subsets, and the amounts of MMPs and TIMPs (tissue inhibitors of MMPs) in order to investigate the possible correlations, if any, between such molecules, collagen loss, and inflammatory cell subsets.

METHODS

Gingival tissue specimens from 6 healthy controls (C) and 6 patients with severe periodontitis (P) were divided into 2 groups. The first group of specimens was frozen and used for the staining of collagen fibers by sirius red F3Ba and for immunohistochemistry with antibodies against CD8, CD4, CD22, CD68, and TIA-1 molecules. The second group was used for organ culture, zymography, Western blotting, and dot blotting. Morphometric and automated image analysis was performed for the evaluation of the area fraction occupied by collagen fibers, the number of inflammatory cell subsets and for enzymatic activities developed by MMPs, and the amounts of TIMPs expressed during periodontal disease.

RESULTS

In group P, the area fraction of collagen fibers (33 +/- 10%) was significantly decreased (P < 0.0002) when compared to group C (60 +/- 7%), and was correlated with the number of all inflammatory cells and amounts of MMPs and TIMPs. In group P, there were significant increases of CD8+, CD22+, CD68+, and TIA-1+ cells, as well as increases in the amounts of MMP-1, MMP-2, MMP-3, MMP-9, and the active form of MMP-9. The active form of MMP-9 and the amount of TIMP-1 were positively correlated with the number of CD22+, CD68+, and TIA-1+ cells.

CONCLUSIONS

The present study showed an imbalance between MMPs and TIMPs associated with the pathologic breakdown of the extracellular matrix during periodontitis. The active form of MMP-9 could be a marker for the clinical severity of periodontal disease.

Collagen fibers and inflammatory cells in healthy and diseased human gingival tissues: a comparative and quantitative study by immunohistochemistry and automated image analysis

BACKGROUND

Periodontal disease is histologically characterized by the degradation of extracellular matrix components associated with a gingival infiltration of inflammatory cell populations. The purpose of this in situ study was to quantify inflammatory cell subsets and the area fraction (AA%) occupied by collagen fibers in healthy and diseased upper gingival connective tissue in order to investigate the association, if any, between collagen loss and inflammatory cell infiltrate.

METHODS

Paraffin gingival tissue sections from 10 healthy controls (C), 9 patients with gingivitis (G), and 10 patients with severe chronic periodontitis (P) were immunohistochemically stained by antibodies against CD45, CD3, CD8, CD20, CD68, TIA-1, and GrB molecules, and the collagen fibers were stained using sirius red F3Ba. The quantitative evaluations of inflammatory cell numbers and the AA% occupied by collagen fibers were performed by morphometric and automated image analysis.

RESULTS

In group P, CD45+, CD20+, CD68+, TIA-1+, and GrB+ cell numbers were significantly increased (P<0.05) when compared to both C and G groups. The present study revealed significant differences (P <0.01) between means of AA% observed in group C (63%), group G (46%), and group P (26%), and AA% of group G and group P was inversely correlated with the numbers of TIA-1+ cells (P<0.01) and GrB+ cells (P<0.01 and P<0.05, respectively).

CONCLUSIONS

This study showed great differences in the number of the distinct inflammatory cell subsets according to the severity of the periodontal disease and suggested that activated cytotoxic cells could play a pivotal role in the loss of collagen fibers observed during these pathological states. During periodontitis, collagen loss was significantly correlated with all inflammatory cell subset numbers. Finally, the quantitative evaluation of the area fraction occupied by gingival collagen fibers may reflect the clinical severity of the periodontal disease.

The importance of data presentation regarding gingival crevicular fluid myeloperoxidase and elastase-like activity in periodontal disease and health status

BACKGROUND

The enzymatic profile of gingival crevicular fluid (GCF) is being analyzed with increasing interest, but related studies lack a general consensus on most methodological points, including the appropriate mode of data presentation.

METHODS

GCF myeloperoxidase (MPO) and elastase-like activity (ELA) levels were spectrophotometrically determined on a total of 60 subjects who were divided into three equal subgroups as early-onset periodontitis (EOP), adult periodontitis (AP), and healthy. GCF enzyme levels were calculated and evaluated both as total enzyme activity and enzyme concentration. The correlations between these GCF enzymes and clinical periodontal status were also analyzed.

RESULTS

With both modes of data presentation, the results regarding MPO activity were consistent. When presented either as total MPO activity or MPO concentration, the periodontally healthy group showed significantly lower MPO activity than the two patient groups (P<0.05). However, two modes of data presentation did not match when GCF ELA was concerned. When data were reported as total ELA, the healthy group exhibited lower enzyme activity (0.02 +/- 0.001 U) than EOP (0.04 +/- 0.01 U) and AP (0.06 +/- 0.02 U) groups; but when reported as concentration, the highest ELA levels were seen in the healthy group (221 +/- 31.53 nmol/min/ml), followed by AP (98.63 +/- 23.03 nmol/min/ml) and EOP (70.49 +/- 12.02 nmol/min/ml) (P<0.05). A strong-positive and significant correlation existed between GCF MPO and ELA. Correlations with clinical parameters were mostly observed with total activities.

CONCLUSIONS

The findings of the present study confirm the relationship between GCF ELA and MPO activity and periodontal disease and also support the functional relativity between the two enzymes. Furthermore, based on these findings, it can be suggested that data presentation by use of total activity seems to be more sensitive in both the reflection of the actual enzymatic profile of GCF and also the existing clinical periodontal status. For each GCF component, the validity of different modes of data presentation should be considered.