Elastase release from gingival crevicular and peripheral neutrophils in periodontitis and health

Protease inhibitor levels in periodontal health and disease

BACKGROUND AND OBJECTIVE

Our previous study showed that protease inhibitors were attenuated by the periodontal pathogen Porphyromonas gingivalis in cultured gingival epithelial cells. We hypothesize that fewer protease inhibitors would be present in more advanced periodontal disease sites, where the level of P. gingivalis may be high. The goal of this study was to investigate the relationship between the protease inhibitor [secretory leukocyte protease inhibitor (SLPI), elastase-specific inhibitor (ELAFIN) and squamous cell carcinoma antigen (SCCA)] levels in gingival crevicular fluid and the number of P. gingivalis micro-organisms in subgingival plaque.

MATERIAL AND METHODS

Plaque samples from subjects without (n = 18) and with moderate to advanced periodontitis (n = 41) were used to quantify P. gingivalis using real-time PCR. Protease inhibitor levels in the gingival crevicular fluid of all the subjects were determined by ELISA.

RESULTS

P. gingivalis was detected in 68.3% of patients with periodontitis, while 16.7% of subjects without periodontitis had a detectable level of P. gingivalis. Patients with periodontitis and P. gingivalis in their plaque exhibited lower SLPI and ELAFIN levels (p < 0.001) compared with control subjects without periodontitis. Secretory leukocyte protease inhibitor was also reduced (p < 0.05) in gingival crevicular fluid of periodontitis patients without a detectable level of P. gingivalis. Periodontitis patients with high vs. low levels of P. gingivalis exhibited reciprocal mean levels of SLPI and ELAFIN concentrations.

CONCLUSION

The reduced concentrations of SLPI and ELAFIN may contribute to the loss of host protective capacity and increase susceptibility to breakdown from chronic infection. The work of this investigation may aid in finding diagnostic and prognostic markers in periodontal health and disease and may also help in finding pharmacological targets directed against periodontal inflammation.

Comparison of gingival crevicular fluid sampling methods in patients with severe chronic periodontitis

BACKGROUND

The analysis of samplings from periodontal pockets is important in the diagnosis and therapy of periodontitis. In this study, three different sampling techniques were compared to determine whether one method yielded samples suitable for the reproducible and simultaneous determination of bacterial load, cytokines, neutrophil elastase, and arginine-specific gingipains (Rgps). Rgps are an important virulence factor of Porphyromonas gingivalis, the exact concentration of which in gingival crevicular fluid (GCF) has not been quantified.

METHODS

GCF was sampled from four sites per patient (one sample per quadrant using two samples per method) in 36 patients with chronic periodontitis. One week later, the procedure was repeated with alternative methods. Variables determined were loads of Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) and P. gingivalis, levels of interleukin-6 and -8, activity of neutrophil elastase, and level of Rgps.

RESULTS

The detected cytokine levels were higher using paper strips compared to paper points. Bacteria were found in similar loads from paper strips and paper points. Rgps were only detectable in high quantities by washing the periodontal pocket. The level of Rgps correlated with the load of P. gingivalis.

CONCLUSIONS

The use of paper strips was suitable for the simultaneous determination of microbial and immunologic parameters. Obtaining GCF by washing can be useful for special purposes. The gingipain concentration in periodontal pockets was directly determined to be ≤1.5 μM. This value indicated that most of the substrates of these proteases by in vitro assays identified until now can be easily degraded in P. gingivalis-infected sites.

Neutrophils in chronic and aggressive periodontitis in interaction with Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans

BACKGROUND AND OBJECTIVE

This study analyzed the interaction of Porphyromonas gingivalis ATCC 33277 and Aggregatibacter actinomycetemcomitans Y4 with peripheral blood polymorphonuclear neutrophils taken from patients with aggressive periodontitis and chronic periodontitis.

MATERIAL AND METHODS

Peripheral blood polymorphonuclear neutrophils obtained from 12 patients with chronic periodontitis, six patients with aggressive periodontitis and 12 healthy controls were exposed to P. gingivalis and A. actinomycetemcomitans following opsonization of the bacteria using the patient's own serum. Serum immunoglobulin G (IgG) levels against both periodontopathogens were measured. Phagocytosis and killing of the bacteria, as well as the extracellular human neutrophil elastase activity, were quantified. The total amount and the extracellular release of reactive oxygen species were measured using luminol-dependent and isoluminol-dependent chemiluminescence.

RESULTS

Polymorphonuclear neutrophils from patients with chronic (62.16 +/- 19.39%) and aggressive (43.26 +/- 26.63%) periodontitis phagocytosed more P. gingivalis than the healthy controls (24.43 +/- 19.87%) at the 30-min time point after exposure to the bacteria (p < 0.05). High serum IgG levels against P. gingivalis and A. actinomycetemcomitans were detected in subjects with periodontitis. Polymorphonuclear neutrophils from subjects with chronic and aggressive periodontitis released significantly more reactive oxygen species and demonstrated greater human neutrophil elastase activity in the absence of any stimulus than polymorphonuclear neutrophils from healthy controls (p < 0.05). Polymorphonuclear neutrophils in chronic periodontitis released significantly more reactive oxygen species when exposed to P. gingivalis and A. actinomycetemcomitans than polymorphonuclear neutrophils in aggressive periodontitis.

CONCLUSION

High serum IgG levels against P. gingivalis and A. actinomycetemcomitans promote phagocytosis in periodontitis. The extracellular release of reactive oxygen species and neutrophil elastase by polymorphonuclear neutrophils may also contribute to damage of the surrounding periodontal tissues.

Salivary non-immunoglobulin agglutinin inhibits human leukocyte elastase digestion of acidic proline-rich salivary proteins

Saliva contains acidic proline-rich salivary proteins that are involved in the formation of the salivary pellicle coating supragingival tooth surfaces. However, human leukocyte elastase, arriving in gingival exudates from inflamed periodontal tissues, degrades the acidic proline-rich salivary proteins, preventing binding to hydroxylapatite surfaces. Here it is reported that high-molecular-weight non-immunoglobulin salivary agglutinin inhibited the proteolytic action of human leukocyte elastase on purified acidic proline-rich salivary proteins. Inhibition was eliminated with monoclonal antibody to a protein determinant on the salivary agglutinin. The addition of antibody against salivary agglutinin blocked the inhibitory effect of parotid saliva on exogenously applied human leukocyte elastase, allowing for the elastase-mediated digestion of the salivary acidic proline-rich salivary proteins. Salivary agglutinin, therefore, is a physiologically important inhibitor of human leukocyte elastase and is able to inhibit elastase-mediated digestion of salivary acidic proline-rich proteins.

Effects of removing the negatively charged N-terminal region of the salivary acidic proline-rich proteins by human leucocyte elastase

Human leucocyte elastase from inflammatory gingival crevicular exudates (gingival crevicular fluid) contacts saliva and saliva-coated tooth surfaces coronal to the gingival margin. Major components of saliva are the salivary acidic proline-rich proteins (PRPs). These acidic PRPs, via the numerous negatively charged amino acid residues located predominantly within their amino-terminal region, bind to the hydroxyapatite mineral of the tooth surface and become part of the salivary pellicle. Thus the potential for human leucocyte elastase-mediated removal of the negatively charged amino-terminal region of acidic PRP variants (PRP-1, PRP-2, PRP-3, PRP-4, PIF-s and PIF-f) was examined. It was determined that each of the acidic PRP variants was susceptible to fragmentation by human leucocyte elastase, in which the 16 amino-terminal segment was removed, leaving the respective residual fragment named as the transitional product (tr). The transitional products were termed PRP-1tr, PRP-2tr (PIF-str), PRP-3tr and PRP-4tr (PIF-ftr). Each of the residual transitional products of acidic PRP had an amino-terminal beginning with serine residue no. 17, determined by amino acid sequencing. When samples of human leucocyte elastase-treated acidic PRPs were placed on native polyacrylamide gels and electrophoresed, the respective transitional products moved more slowly than the parental acidic PRP molecules, reflecting the loss of a portion of the negatively charged section. In comparison to the acidic PRPs, the acidic PRP transitional products had markedly reduced binding to hydroxyapatite. The transitional products were resistant to further enzymatic digestion as a function of increased incubation time and appeared to exert an antihuman leucocyte elastase effect. However, when increased concentrations of human leucocyte elastase were incubated with the acidic PRP, a more extensive digestion occurred, leaving a residual peptide with an amino-terminal beginning with alanine residue no. 44. Interestingly, intact acidic PRPs if prebound to hydroxyapatite particles, resisted digestion by human leucocyte elastase. In summary, human leucocyte elastase was capable of digesting fluid-phase (unbound) acidic PRP in a manner that eliminated part of their negatively charged region, which subsequently reduced their binding to hydroxyapatite. High concentrations of human leucocyte elastase, arriving from inflammatory gingival crevicular exudates, may interrupt the normal binding of fluid-phase acidic PRPs to hydroxyapatite.

Smokeless tobacco extracts activate complement in vitro: a potential pathogenic mechanism for initiating inflammation of the oral mucosa

The use of smokeless tobacco has been linked to an increased incidence of inflammation of the buccal and gingival mucosa. However, the mechanisms by which smokeless tobacco initiates inflammation are not well understood. The complement cascade is a ubiquitous source of proinflammatory molecules and can be activated rapidly by a wide variety of agents. Therefore, the effect of smokeless tobacco on complement was investigated as a potential pathogenic mechanism for triggering inflammation of the oral mucosa. Aqueous extracts of loose leaf chewing tobacco (1S1), dry snuff (1S2), and moist snuff (1S3), added to normal human serum, depleted complement hemolytic activity in a dose-dependent manner. Experiments utilizing sera deficient in one specific complement component indicated that the smokeless tobacco-induced depletion of hemolytic activity was due largely to consumption of C3. Furthermore, assays designed to test the activity of the alternative pathway of complement clearly showed that all three extracts depleted the hemolytic activity of this pathway. Finally, all three smokeless tobacco extracts activated the alternative pathway since significantly elevated levels of the cleavage fragments iC3b and Bb were detected in extract-treated serum. High quantities of the classical pathway cleavage fragment C4d also were detected in serum treated with moist snuff (1S3). The results clearly demonstrate that smokeless tobacco extracts activate the alternative pathway and also suggest some measure of classical pathway activation. Activation of complement by smokeless tobacco may be a mechanism for initiating inflammation of the oral mucosa.

Salivary levels of alpha 2-macroglobulin, alpha 1-antitrypsin, C-reactive protein, cathepsin G and elastase in humans with or without destructive periodontal disease

Five host-response indicators were measured by enzyme-linked immunosorbent assays on unstimulated whole saliva samples from 45 adults (19 male, 26 female). The participants were distributed among four dentate groups representing oral health (I), gingivitis (II), moderate periodontitis (III), and severe periodontitis (IV), and one group of edentulous volunteers (V). Levels of the host-response indicators varied widely, from zero, primarily with groups I and V, to relatively high values with groups II, III and IV. The levels ranged as follows: alpha 2-macroglobulin, 0-4941 ng/ml; alpha 1-antitrypsin, 2-2271 ng/ml; C-reactive protein, 0-472 pg/ml; cathepsin G, 0-6035 ng/ml; elastase, 0-164 ng/ml (free), 0-732 ng/ml (bound to alpha 1-antitrypsin), and 0-318 ng/ml (bound to alpha 2-macroglobulin). Statistical evaluation by planned contrasts showed that levels of host-response indicators for group I were significantly lower (except for alpha 1-antitrypsin) than for groups II, III, and IV. A trend analysis of groups I-IV showed that mean scores (again, except for alpha 1-antitrypsin) increased significantly in a positive, monotonic manner. Group V showed significantly lower values for elastase than in the other groups. The findings demonstrate that these factors can be detected in whole saliva and suggest that, except for alpha 1-antitrypsin, their levels are directly related to an individual's periodontal status.