Proteolytic host cell enzymes in gingival crevice fluid

Elafin is specifically inactivated by RgpB from Porphyromonas gingivalis by distinct proteolytic cleavage

Abstract Porphyromonas gingivalis, the major causative bacterium of periodontitis, contributes significantly to elevated proteolytic activity at periodontal pockets owing to the presence of both bacteria and host, predominantly neutrophil-derived, serine proteases. Normally the activity of the latter enzymes is tightly regulated by endogenous proteins, including elafin, a potent neutrophil elastase and proteinase 3 inhibitor released from epithelial cells at sites of inflammation. Here, we report that all three gingipains (HRgpA, RgpB, and Kgp) have the ability to degrade elafin, with RgpB being far more efficient than other gingipains. RgpB efficiently inactivates the inhibitory activity of elafin at subnanomolar concentrations through proteolysis limited to the Arg22-Cys23 peptide bond within the surface loop harboring the inhibitor active site. Notably, elafin resists inactivation by several Staphylococcus aureus-derived serine and cysteine proteases, confirming the high stability of this protein against proteolytic degradation. Therefore, we conclude that elafin inactivation by RgpB represents a specific pathogenic adaptation of P. gingivalis to disturb the protease-protease inhibitor balance in the infected gingival tissue. This contributes to enhanced degradation of host proteins and generation of a pool of peptides serving as nutrients for this asaccharolytic pathogen.

Involvement of Cytosolic Phospholipase A2α in MMP-9 Up-regulation

Matrix metalloproteinase-9 (MMP-9) is important in the pathogenesis of periodontitis. Cytosolic phospholipase A2α (cPLA2α) is involved in MMP-9 up-regulation in human monocytes. We tested the hypothesis that cPLA2α also regulates MMP-9 induction by Fusobacterium nucleatum and by phorbol 12-myristate-13-acetate (PMA) in gingival epithelial cells. While PMA induced MMP-9 expression considerably, F. nucleatum did so moderately. This time-course study demonstrated that MMP-9 mRNA up-regulation occurred at 3 hours, whereas MMP-9 secretion and activity in cell-free supernatants occurred at 12 hours. cPLA2α mRNA was constitutively expressed in gingival epithelial cells. Transient activation of cPLA2 by Ser505 phosphorylation was observed in the nuclei upon stimulation, suggesting its role as a transcription factor, while cPLA2 protein expression remained unchanged. Induction of MMP-9 expression and activity was significantly inhibited by 1 μM of the specific cPLA2α inhibitor (P < 0.01). These findings demonstrate the involvement of cPLA2α in MMP-9 up-regulation.

HPLC-ESI-MS analysis of oral human fluids reveals that gingival crevicular fluid is the main source of oral thymosins beta(4) and beta(10)

Thymosin beta(4) (Tbeta(4)), its sulfoxide, and thymosin beta(10 )(Tbeta(10)) were detected in human saliva and identified by different strategies based on RP HPLC coupled to electrospray multidimensional IT MS. Tbeta(4 )was almost always detected in whole saliva, its sulfoxide sporadically, Tbeta(10) rarely. Tbeta(4) was undetectable in parotid saliva and less concentrated in submandibular/sublingual saliva than in whole saliva. Analysis of gingival crevicular fluid revealed high relative amounts of Tbeta(4), Tbeta(4) sulfoxide, and Tbeta(10) in all the samples. Tbeta(4) mean concentration was 200 times higher in crevicular fluid (20 micromol/L, N = 9) than in whole saliva (0.1 micromol/L, N = 9). Crevicular fluid concentration of Tbeta(4 )(ca. 5% represented by its sulfoxide) and beta(10 )significantly correlated (r = 0.856; N = 9), and their ratio was about 5. A significant correlation was also observed between Tbeta(4 )concentrations in whole saliva and gingival crevicular fluid (r = 0.738; N = 9). Immunohistochemical analysis of the major salivary glands showed that immunoreactivity for Tbeta(4) is restricted to ductal cells, with minor degree of focal positivity in some acinar cells. On the whole, results indicate that gingival sulcus is a main, although not the sole, source for oral Tbeta(4 )and Tbeta(10).

Early wound healing following one-stage dental implant placement with and without antibiotic prophylaxis: a pilot study

BACKGROUND

One-stage implant placement has clinically acceptable treatment outcomes. Among other advantages, it may allow investigation of early wound healing. The purpose of this pilot study was to determine whether peri-implant crevicular fluid (PICF) can be used to detect early changes around implants placed with one-stage surgical protocol following 1 week of healing.

METHODS

Twenty subjects (11 males and nine females; aged 22 to 72 years; two smokers) were included. Exclusion criteria were allergies to amoxicillin and systemic conditions that may affect healing. Subjects had a healthy periodontium and needed a single implant; eight received antibiotic prophylaxis, and 12 served as controls. Clinical healing was evaluated with plaque and gingival indices (PI and GI, respectively). Gingival crevicular fluid (GCF) from the surgical site was obtained prior to the surgery, whereas PICF was collected at the 1-week visit. Enzyme-linked immunosorbent assay was used to determine GCF/PICF interleukin (IL)-1beta and -8 concentrations. Peripheral blood and GCF antibiotic levels were measured by high-performance liquid chromatography.

RESULTS

Postoperative PI and GI were slightly increased. Total GCF and PICF volumes did not show a significant difference between appointments. There was an increase in PICF IL-1beta and -8 levels at 1 week postoperatively. Mean amoxicillin serum concentration was 5.1 +/- 2 microg/ml at 1 to 4 hours following the initial dose, whereas GCF amoxicillin levels were below the limit of detection. Antibiotic prophylaxis had a modest effect on clinical indices (PI and GI) and no appreciable effect on biomarkers.

CONCLUSIONS

PICF content can be studied as early as 1 week following one-stage implant placement. The results raise doubts regarding the clinical usefulness of amoxicillin prophylaxis.

Stimulation of epithelial cell matrix metalloproteinase (MMP-2, -9, -13) and interleukin-8 secretion by fusobacteria

BACKGROUND/AIMS

Bacterial pathogens involved in periodontal diseases exert their destructive effects primarily by stimulating the host cells to increase their secretion of proinflammatory cytokines and matrix metalloproteinases (MMPs). This study aimed to determine the epithelial cell matrix metalloproteinase and interleukin-8 (IL-8) secretion upon exposure to fusobacteria.

METHODS

Eight different oral and non-oral Fusobacterium strains were incubated with HaCaT epithelial cells. Gelatin zymography and Western blot analysis were performed to detect collagenase 3 (MMP-13), gelatinase A (MMP-2), gelatinase B (MMP-9), and IL-8 secretion by epithelial cells.

RESULTS

All Fusobacterium strains, especially Fusobacterium necrophorum ATCC 25286, Fusobacterium nucleatum ATCC 25586, and Fusobacterium varium ATCC 51644, increased MMP-9 and MMP-13 secretion. Fusobacterium simiae ATCC 33568, and to a lesser extent F. nucleatum and F. necrophorum, increased epithelial MMP-2 secretion. F. nucleatum and F. necrophorum also increased IL-8 secretion. F. varium ATCC 27725, a strain that only weakly stimulated MMP production, strongly increased the IL-8 production, suggesting that their expression is differently regulated.

CONCLUSION

We conclude that the pathogenic potential of fusobacteria may partly result from their ability to stimulate secretion of MMP-9, MMP-13, and IL-8 from epithelial cells.

Treponema denticola lipooligosaccharide activates gingival fibroblasts and upregulates inflammatory mediator production

In response to bacterial challenges, fibroblasts, a major constituent of gingival connective tissue, can produce immunoregulatory cytokines and proteolytic enzymes that may contribute to tissue destruction and the progression of periodontitis, a chronic inflammatory disease affecting tooth-supporting tissues, including alveolar bone. The spirochete Treponema denticola is a major etiological agent of periodontitis and can invade oral tissues. The aim of the present study was to investigate the inflammatory response of gingival fibroblasts to T. denticola lipooligosaccharide (LOS). T. denticola LOS induced significant production of various inflammatory mediators by fibroblasts, including interleukin-6, interleukin-8, monocyte chemoattractant protein 1, nitric oxide, and prostaglandin E(2). In addition, the secretion of matrix metalloproteinase 3, an enzyme active on basement membrane components, was also significantly increased. The response of fibroblasts was dose-dependent and much stronger following a 24 h stimulation period. The expression and/or phosphorylation state of several signaling proteins, including Fos, MKK1, MKK2, MKK3/6, NF-kappaB p50, and NF-kappaB p65, was enhanced following stimulation of fibroblasts with T. denticola LOS. In summary, T. denticola LOS induced an inflammatory response in gingival fibroblasts and may thus contribute to the immunopathogenesis of periodontitis and the progression of the disease.

Characteristics of collagenase-2 from gingival crevicular fluid and peri-implant sulcular fluid in periodontitis and peri-implantitis patients: pilot study

OBJECTIVE

To compare collagenase activity and collagenolytic matrix metalloproteinase (MMP) levels in gingival crevicular fluid (GCF) and in peri-implant sulcular fluid (PISF) in gingivitis (G), chronic periodontitis (CP), and peri-implantitis (PI) human subjects.

MATERIAL AND METHODS

GCF and PISF were collected on filter paper strips, volume was determined, and samples were extracted in buffer containing general proteinase but not MMP inhibitors. Collagenase activity was measured using a DNP-synthetic octapeptide, and molecular and activation forms of collagenase-2 by Western immunoblotting.

RESULTS

GCF from CP and G sites exhibited elevated collagenase activity and flow, but collagenase concentrations expressed per microl were not significantly different between the healthy and G sites. Minimal fluid was obtained from healthy PISF, and collagenase concentration was the same or lower than in healthy GCF. Although PISF flow was 34% lower than GCF flow in CP subjects, collagenase concentration in CP and in PI sites was 78% and 971% greater, respectively, than in the appropriate healthy sites. Western immunoblot revealed MMP-8 in both PISF and GCF; fibroblast-type MMP-8 was not detected in healthy GCF and PISF. Immunoreactivity level and inactive and activated forms of PMN-type MMP-8 in GCF and PISF increased with the severity of periodontitis and peri-implantitis. Enhanced levels of fibroblast-type MMP-8 in active form were detected only in severe CP GCF and PI PISF.

CONCLUSIONS

Peri-implantitis PISF contained higher collagenase-2 levels and activity than GCF from similar deep CP sites. GCF and PISF from severe CP and PI exhibited the highest activation of MMP-8 isoenzymes species (PMN and fibroblast-type).

Proteolytic Activities of Oral Bacteria on ProMMP-9 and the Effect of Synthetic Proteinase Inhibitors

Tissue reactions to bacteria lead to proinflammatory reactions involving matrix metalloproteinases (MMPs). Synthetic protease inhibitors may offer new possibilities to regulate bacterial proteases. We investigated proteolytic activities of certain periodontal bacteria, their effects on the latent proMMP-9, and the effects of synthetic MMP inhibitors and a serine protease inhibitor Pefabloc. The strains studied were Porphyromonas gingivalis, Prevotella intermedia, Peptostreptoccus micros, Prevotella nigrescens, Fusobacterium nucleatum, and 5 Aggregatibacter actinomycetemcomitans serotypes. Their gelatinolytic activities and the effects of certain synthetic MMP inhibitors and Pefabloc were analyzed by zymography. Bacterial effects on proMMP-9 conversion were investigated by Western immunoblot. All investigated periodontal bacteria produced gelatinolytic cell-bound and extracellular proteinases which could fragment latent proMMP-9, suggesting co-operative processing cascades in oral tissue remodeling. A. actinomycetemcomitans produced the weakest gelatinolytic activity. Synthetic proteinase inhibitors exhibited slight but clear reductive effects on the bacterial proteolytic activities. We conclude that targeted anti-proteolytic treatment modalities against bacterial-host proteolytic cascades can be developed.

Matrix metalloproteinase levels in children with aggressive periodontitis

BACKGROUND

Matrix metalloproteinases (MMPs) are a family of host-derived proteinases reported to mediate multiple functions associated with periodontal destruction and inflammation. Most of the existing data have been gathered from adults with chronic periodontitis. The purpose of this study was to determine the MMP levels in a cohort of African American children with and without aggressive periodontitis.

METHODS

Gingival crevicular fluid (GCF) was collected in a cohort of 44 African American children, 7 to 19 years of age, with and without aggressive periodontitis (AgP) and compared to healthy unrelated children and to adults with chronic periodontitis (CP). GCF volume was determined with a calibrated gingival fluid meter. The samples were assayed for MMP-1, -2, -3, -8, -9, -12, and -13 using fluorimetric substrates.

RESULTS

The MMP levels from diseased sites in the subjects with AgP were statistically higher (P <0.05) in almost all instances than those associated with the unrelated controls or with the subjects with CP. MMP-8 was significantly elevated in the diseased sites of the children with AgP relative to non-diseased sites in the same children (P = 0.002), as well as the siblings, non-diseased controls, and subjects with CP (P < or =0.0001). There was no positive correlation between probing depth and any MMP level.

CONCLUSIONS

MMP levels were elevated in AgP sites relative to non-diseased sites in the same subjects, in siblings, and in unrelated controls. MMPs associated with the AgP sites in children were generally elevated compared to an adult cohort with a history of CP.

Effects of platelet-derived growth factor isoforms on plasminogen activation by periodontal ligament and gingival fibroblasts

BACKGROUND AND OBJECTIVE

Platelet-derived growth factor isoforms and components of the plasminogen activator system are expressed at higher levels during periodontal regeneration. Recombinant platelet-derived growth factor-BB is approved for the treatment of periodontal defects. In the present study we investigated the effect of platelet-derived growth factor isoforms on the plasminogen activator system in periodontal fibroblasts.

MATERIAL AND METHODS

Human periodontal ligament fibroblasts and gingival fibroblasts were exposed to platelet-derived growth factor isoforms. Changes in urokinase-type plasminogen activator, tissue-type plasminogen activator, plasminogen activator inhibitor-1 and plasminogen activator inhibitor-2 transcript levels by platelet-derived growth factor-BB were monitored with a quantitative reverse transcription-polymerase chain reaction. Urokinase-type plasminogen activator and plasminogen activator inhibitor-1 protein levels were assessed by immunoassays. The effects of platelet-derived growth factor-BB on mitogen-activated protein kinase and phosphoinositol-3 kinase/Akt signaling were investigated by western blot and inhibitor studies. Casein zymography and kinetic assays revealed the size and activity, respectively, of the plasminogen activators.

RESULTS

We found that incubation of periodontal ligament fibroblasts and gingival fibroblasts with platelet-derived growth factor-BB resulted in enhanced levels of urokinase-type plasminogen activator and plasminogen activator inhibitor-1 transcripts, but not of tissue-type plasminogen activator and plasminogen activator inhibitor-2. Platelet-derived growth factor-BB also increased urokinase-type plasminogen activator and plasminogen activator inhibitor-1 release into the culture medium. Phosphorylation of extracellular signal-regulated kinase, p38, c-Jun N-terminal kinase and Akt was observed in fibroblasts of both origin. Inhibition of phosphoinositol-3 kinase signaling abrogated the platelet-derived growth factor-BB effect on plasminogen activator inhibitor-1 production. Casein zymography revealed enzymatic activity of the urokinase-type plasminogen activator in cell-conditioned media and lysates of periodontal ligament fibroblasts and gingival fibroblasts. Exposure of gingival fibroblasts, but not of periodontal ligament fibroblasts, to platelet-derived growth factor isoforms moderately increased total plasminogen activation in the medium.

CONCLUSION

These findings suggest that periodontal ligament fibroblasts attempt to maintain an equilibrium of the plasminogen activator system in the presence of platelet-derived growth factor isoforms.

Degradation of noncollagenous components by neutrophil elastase reduces the mechanical strength of rat periodontal ligament

BACKGROUND AND OBJECTIVE

We have previously shown that increases in neutrophil elastase in periodontal ligament with chronic periodontitis results in degradation of the noncollagenous components. The purpose of this study was to investigate whether the destruction of noncollagenous components by treatment with elastase in vitro causes changes in the mechanical properties of the periodontal ligament.

MATERIAL AND METHODS

The transverse sections of mandibular first molars, prepared from male Wistar rats at 6 wk of age, were digested with 0-50 microg/mL of neutrophil elastase at 37 degrees C for 4 h. Then, their mechanical properties and morphological features were examined.

RESULTS

Digestion with elastase dose-dependently decreased the maximum shear stress and failure strain energy density of the periodontal ligament (p < 0.05-0.01). The histological observations after digestion revealed marked degradation of oxytalan fibers, but no marked changes of the collagen fibers, which was confirmed by the detection of very low quantities of hydroxyproline in the digest. The light and scanning electron micrographs showed that the elastase degraded the interfibrillar substances in the periodontal ligament and exposed individual collagen fibrils.

CONCLUSION

These results suggest that the increased neutrophil elastase observed in periodontal disease degrades the oxytalan fibers and interfibrillar substances in the periodontal ligament to decrease its mechanical strength.

Tumor Necrosis Factor-α-converting Enzyme (TACE) Levels in Periodontal Diseases

Tumor necrosis factor-α-converting enzyme (TACE) is a metalloprotease which can shed several cytokines from the cell membrane, including receptor activator of NF-κB ligand (RANKL). This study aimed to investigate the hypothesis that TACE would be elevated in the gingival crevicular fluid (GCF) of persons with periodontitis. Total TACE amounts in GCF were higher in persons with chronic and aggressive periodontitis than in those with gingivitis or in healthy persons. TACE concentrations in GCF were higher in persons with chronic and aggressive periodontitis than in those with gingivitis, although not significantly higher than in healthy persons. Persons with chronic periodontitis receiving immunosuppressive treatment exhibited over 10-fold lower TACE levels than the other periodontitis groups. TACE was positively correlated with probing pocket depth, clinical attachment levels, and RANKL concentrations in GCF. In conclusion, the increased GCF TACE levels in persons with periodontitis and their positive correlation with RANKL may indicate an association of this enzyme with alveolar bone loss, and may warrant special attention in future therapeutic approaches.

Matrix metalloproteinase-2, -9, and -12 gene polymorphisms in generalized aggressive periodontitis

BACKGROUND

Matrix metalloproteinases (MMPs) are involved in periodontal tissue remodeling and degradation. Polymorphisms in the promoter region of the MMP-2 and -9 genes and in the coding region of the MMP-12 gene could affect transcription and the function of these enzymes. The aim of the present study was to determine the association between the aforementioned MMP polymorphisms and generalized aggressive periodontitis (GAgP).

METHODS

Genomic DNA was obtained from the peripheral blood of 92 subjects with GAgP and 157 periodontally healthy subjects. MMP-2 -735C/T, MMP-9 -1562C/T, and MMP-12 357Asn/Ser polymorphisms were genotyped by polymerase chain reaction and restriction fragment length polymorphism. Probing depth, clinical attachment loss, supragingival plaque accumulation, and bleeding on probing were recorded. The data were analyzed by chi(2), logistic regression, and Mann-Whitney U tests.

RESULTS

The genotype distributions, allele frequencies, and rare allele carriage of MMP-2 and MMP-12 genes were similar in GAgP and healthy subjects (P >0.05). T allele frequency and T allele carriage of the MMP-9 -1562 C/T polymorphism were significantly lower in the GAgP group than in the healthy group (P <0.05). In addition, logistic regression analysis revealed a protective effect for MMP-9 -1562 T allele carriers (odds ratio = 0.52; P = 0.04).

CONCLUSIONS

MMP-2 -735C/T and MMP-12 357Asn/Ser polymorphisms are not related to GAgP. Conversely, the MMP-9 -1562 gene T allele might be associated with a decreased risk for GAgP in the Turkish population.

Experimental tooth pain elevates substance P and matrix metalloproteinase-8 levels in human gingival crevice fluid

OBJECTIVE

Tooth pain can induce a neurogenic inflammatory reaction in gingiva in association with local elevations of matrix metalloproteinase (MMP)-8, which is considered the major tissue destructive protease in gingival crevice fluid (GCF). The pro-inflammatory neuropeptides released by sensory nerves coordinate the activities of the immuno-effector cells and may influence the secretion of MMP-8. With this background, we studied whether experimental tooth pain can trigger changes in GCF levels of the neuropeptide substance P (SP) and MMP-8.

MATERIAL AND METHODS

The GCF SP levels of stimulated and non-stimulated teeth were analyzed for SP using a competitive enzyme immunoassay (EIA). The GCF MMP-8 levels were determined by quantitative immunofluorometric assay (IFMA).

RESULTS

Painful stimulation of the upper central incisor caused significant elevations in GCF SP and MMP-8 levels of the stimulated tooth. At the same time, the GCF SP and MMP-8 levels of non-stimulated control teeth were unchanged.

CONCLUSIONS

These data indicate that experimental tooth pain can induce local elevations of SP and MMP-8 levels in GCF simultaneously. This supports the possibility of a local neurogenic spread of inflammatory reactions from intrapulpal to surrounding periodontal tissues.

Gene polymorphisms of matrix metalloproteinase-2, -9 and -12 in periodontal health and severe chronic periodontitis

AIM

Matrix metalloproteinases (MMPs) are involved in periodontal tissue remodeling and degradation. MMP polymorphisms could alter transcription and function of these enzymes. The aim of this study was to investigate MMP-2, MMP-9 and MMP-12 gene polymorphisms in relation to susceptibility to severe chronic periodontitis (CP).

METHODS

Genomic DNA was obtained from peripheral blood of 87 severe CP patients and 107 periodontally healthy subjects. MMP-2 -735C/T, MMP-9 -1562C/T and MMP -12357Asn/Ser gene polymorphisms were genotyped by polymerase chain reaction and restriction fragment length polymorphism. Probing depth, clinical attachment loss, supragingival plaque accumulation and bleeding on probing were recorded. The data were analyzed by chi-square, logistic regression and Mann-Whitney-U-tests.

RESULTS

The genotype distributions and allele frequencies of MMP-2, MMP-9 and MMP-12 genes were similar in CP and healthy subjects (p>0.05). Differences between rare allele carriage rates of CP and healthy groups regarding MMP-2, MMP-9 and MMP-12 gene polymorphisms were not significant (p>0.05). However, T allele carriers of MMP-9 -1562 gene had less risk for CP (OR=0.36; 95% CI=0.16-0.81).

CONCLUSION

These data suggest that MMP-2 -735C/T, MMP-9 -1562C/T and MMP-12 357Asn/Ser polymorphisms are not associated with susceptibility to severe CP in Turkish population. However, T allele of MMP-9 -1562 gene might be associated with decreased susceptibility to severe CP.

Synthesis and evaluation of novel heterocyclic MMP inhibitors

A variety of novel heterocyclic compounds were synthesized and evaluated for MMP inhibition. Broad spectrum inhibition of MMPs 1, 2, 9, and 12 was found with pyridinone-based compounds while N-heterocyclic triazoles and tetrazoles were largely ineffective. A highly selective tetrazole inhibitor for MMP-2 was discovered.

The enamel matrix derivative (Emdogain) enhances human tongue carcinoma cells gelatinase production, migration and metastasis formation

Enamel matrix derivative Emdogain (EMD) is widely used in periodontal treatment to regenerate lost connective tissue and to improve the attachment of the teeth. Gelatinases (MMP-2 and -9) have an essential role in the promotion and progression of oral cancer growth and metastasis formation. We studied the effects of EMD on human tongue squamous cell carcinoma (HSC-3) cells in vitro and in vivo. In vitro, EMD (100 microg/ml and 200 microg/ml) remarkably induced the MMP-2 and -9 production from HSC-3 cells analysed by zymography and enzyme-linked immunosorbent assay. EMD also slightly induced the MMP-2 and -9 production from benign human mucosal keratinocytes (HMK). Furthermore, EMD clearly induced the transmigration of HSC-3 cells but had no effect on the HMK migration in transwell assays. The in vitro wound closure of HSC-3 cells was notably accelerated by EMD, whereas it had only minor effect on the wound closure of HMKs. The migration of both cell lines was inhibited by a selective cyclic anti-gelatinolytic peptide CTT-2. EMD had no effect on HSC-3 cell proliferation or apoptosis and only a limited effect on cell attachment to various extracellular matrix components. The in vivo mice experiment revealed that EMD substantially induced HSC-3 xenograft metastasis formation. Our results suggest that the use of EMD for patients with oral mucosal carcinomas or premalignant lesions should be carefully considered, possibly avoided.

MMP-13 and TIMP-1 determinations in progressive chronic periodontitis

Matrix metalloproteinase (MMP)-13 is a collagenase involved in extracellular matrix degradation either by its direct degradative effects or by processing bioactive substrates. The aim of this study was to determine the levels of MMP-13 and tissue inhibitor of metalloproteinase (TIMP)-1 in gingival crevicular fluid (GCF) and gingival biopsies obtained from active and inactive sites during chronic periodontitis progression.

MATERIALS AND METHODS

This was a longitudinal study in which chronic periodontitis patients with moderate to severe disease were included and followed until they developed progression determined by the tolerance method. GCF samples were obtained from periodontitis, active, inactive and healthy sites and additional gingival biopsies were taken from active and inactive sites. MMP-13 and TIMP-1 determinations were carried out by immunodot blots and immunowestern blots.

RESULTS

In progressive periodontitis, MMP-13 and TIMP-1 remained unchanged between active and inactive sites, but as the TIMP-1 relative levels increased together with MMP-13 elevation in inactive samples, an inverse correlation was observed in active sites. Besides, MMP-13 was undetectable in healthy controls.

CONCLUSION

Chronic periodontitis is characterized by increased MMP-13 expression. During disease progression, active sites tended to decrease TIMP-1 levels in association with MMP-13 elevation.

Effect of pepsin on erosive tissue loss and the efficacy of fluoridation measures in dentine in vitro

OBJECTIVES

In dentine, erosive lesion progression and efficacy of fluoridation measures for symptomatic therapy of dental erosion are both dependent on the presence of the organic matrix. In patients with eating disorders in combination with chronic vomiting, the demineralized organic matrix can be degraded by gastric enzymes. The aim of this study was to investigate the effect of pepsin on erosion progression and the efficacy of fluoride in dentine.

MATERIAL AND METHODS

Human dentine specimens were prepared and randomly divided into 4 groups of 20 specimens each. They were subjected to a cyclic de- and remineralization procedure for 9 days. For demineralization (6 x 2 min per day), an HCl solution (pH 1.6) was used in all groups. In two groups, pepsin (1.5 mg mL(-1)) was added to the demineralization solution. Fluoridation was performed in two groups 6 x 1 min per day with a mouth rinse (Olaflur/SnF(2); 250 ppm F(-)) after demineralization with both the HCl solution and the pepsin containing solution. Degradation of collagen was quantified by analyzing hydroxyproline and tissue loss was determined microradiographically. SEM images were taken in addition.

RESULTS

In the pepsin group, 1.72 (0.26) microg mL(-1) (mean (SD)) hydroxyproline per day was detected, and in the pepsin-fluoride group 1.95 (0.50) microg mL(-1). Tissue loss after 9 days in the control group was similar to that in the pepsin group (122.2 (53.4) microm and 122.2 (38.0) microm, n.s., respectively). Fluoridation reduced tissue loss after demineralization (98.8 (30.2) microm) but not after pepsin treatment (125.2 (34.2) microm; p< or =0.05).

CONCLUSION

Under the conditions used, pepsin had no influence on tissue loss, but altered the efficacy of fluoridation measures.

Stimulatory response of neutrophils from periodontitis patients with periodontal pathogens

OBJECTIVE

Neutrophils play a crucial role in the defense of invading bacteria by releasing biologically active molecules. The response of peripheral blood neutrophils was studied in periodontitis-affected patients and in healthy controls towards stimulation to Porphyromonas gingivalis (Pg) and Actinobacillus actinomycetemcomitans (Aa) extracts.

MATERIALS AND METHODS

Peripheral venous blood was drawn from 23 adult patients with moderate to advanced chronic periodontitis (probing depth >or=5 mm, attachment loss >or=3 mm), and 30 healthy volunteers. Neutrophil response followed by metalloproteinase-9 (MMP-9) and interleukin-8 (IL-8) secretion was assayed by zymography and enzyme-linked immunosorbent assay, respectively, on both whole blood and purified neutrophils. In addition to periodontal pathogen extracts, known stimulating agents were tested, such as Escherichia coli-lipopolysaccharide (LPS), phytohemagglutinin, and zymosan A.

RESULTS

Neutrophil response, expressed as a secretion ratio under stimulated and non-stimulated conditions, measured in whole blood, showed no differences between periodontitis and healthy controls. Instead, in purified neutrophils from patients, MMP-9 exhibited a significantly higher secretion ratio with LPS and Pg (1.5- to 2-fold), whereas IL-8 showed a larger increase in secretion ratio (3- to 7-fold) in the presence of Pg, Aa, LPS, and zymosan A.

CONCLUSION

Peripheral neutrophils of periodontitis-affected patients are more reactive as suggested by their significantly higher response toward periodontal pathogen extracts and other stimulating agents.

Plasminogen activation by fibroblasts from periodontal ligament and gingiva is not directly affected by chemokines in vitro

OBJECTIVE

Chronic inflammation in periodontal disease is associated with increased plasminogen activation and elevated levels of chemokines. It is unknown whether chemokines can regulate the activation of plasminogen via modulation of plasminogen activators (PA) and the corresponding plasminogen activator inhibitors (PAI) in periodontal tissue.

DESIGN

To establish a link between chemokines and activation of plasminogen, human periodontal ligament fibroblasts (PDL) and gingival fibroblasts (GF) were incubated with IL-8, monocyte chemoattractant protein-1, macrophage inflammatory protein-1alpha, and platelet factor-4, either alone or in the presence of the inflammatory mediators TGF-beta and IL-1. The potential of the cell lysates to activate plasminogen was based on kinetic studies with the substrate casein. Casein zymography was performed to determine the molecular sizes of the PA. Total PAI-1 in the cell-conditioned medium was quantified by immunoassay.

RESULTS

We report that the chemokines did not affect activation of plasminogen by PDL and GF. Even in the presence of TGF-beta which suppressed, and IL-1 which stimulated plasminogen activation, the chemokines had no direct effect. Inhibition of PA and plasmin, but not of matrix metalloproteinases and cysteine proteinases prevented caseinolysis. The plasminogen activation capacity of the cell lysates was represented by a single band with features of uPA. The immunoassay showed that the release of PAI-1 in PDL and GF remained unaffected by the chemokines, also when stimulated with TGF-beta.

CONCLUSIONS

These results suggest that plasminogen activation by PDL and GF is not directly affected by the chemokines even in the presence of the inflammatory mediators TGF-beta and IL-1.

Inhibition of host extracellular matrix destructive enzyme production and activity by a high-molecular-weight cranberry fraction

BACKGROUND AND OBJECTIVE

Periodontal diseases are a group of inflammatory disorders that are initiated by specific gram-negative bacteria and lead to connective tissue destruction. Proteolytic enzymes, including matrix metalloproteinases (MMPs) and elastase, produced by resident and inflammatory cells in response to periodontopathogens and their products, play a major role in gingival tissue destruction. The aim of this study was to investigate the effect of a high-molecular-weight fraction prepared from cranberry juice concentrate on MMP-3, MMP-9 and elastase activities, as well as on MMP production by human cells stimulated with lipopolysaccharide of Actinobacillus actinomycetemcomitans.

MATERIAL AND METHODS

MMP-3 and MMP-9 production by gingival fibroblasts and macrophages treated with the cranberry fraction and then stimulated with lipopolysaccharide was measured by enzyme-linked immunosorbent assay. MMP-3, MMP-9 and elastase activities in the presence of the cranberry fraction were evaluated using colorimetric or fluorogenic substrates. The changes in expression and phosphorylation state of fibroblast intracellular signaling proteins induced by A. actinomycetemcomitans lipopolysaccharide and the cranberry fraction were characterized by antibody microarrays.

RESULTS

The lipopolysaccharide-induced MMP-3 and MMP-9 responses of fibroblasts and macrophages were inhibited in a dose-dependent manner by the cranberry fraction. This fraction was found to inhibit fibroblast intracellular signaling proteins, a phenomenon that may lead to a down-regulation of activating protein-1 activity. MMP-3, MMP-9 and elastase activities were also efficiently inhibited by the cranberry fraction, even when it was used at low concentrations.

CONCLUSION

These results suggest that cranberry compounds offer promising perspectives for the development of novel host-modulating strategies for an adjunctive treatment of periodontitis.

Regulation of matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases by Porphyromonas gingivalis in an engineered human oral mucosa model

Under physiological conditions, matrix metalloproteinases (MMPs) are involved in the remodeling and turnover of periodontal tissue and their activity is tightly regulated by tissue inhibitors of metalloproteinases (TIMPs). Disturbances in the balance between MMPs and TIMPs may result in excessive tissue destruction. We previously used an engineered human oral mucosa (EHOM) model to demonstrate that Porphyromonas gingivalis, a major etiological agent of periodontitis, infiltrates connective tissue and induces significant loss of attachment of the stratified epithelium from the basement membrane. The aim of the present study was to investigate the effect of P. gingivalis on the expression and production of MMP-2, MMP-9, TIMP-1, and TIMP-2 by oral fibroblasts and epithelial cells. The EHOM model was infected with P. gingivalis ATCC 33277 or its derivative gingipain-null mutant (KDP128) for different periods of time. MMP and TIMP mRNA expression was evaluated by reverse transcription-polymerase chain reaction (RT-PCR) analysis, while protein secretion into the culture medium was assessed by enzyme-linked immunosorbent assays. P. gingivalis significantly up-regulated MMP-2 and MMP-9 mRNA expression by oral epithelial cells. This MMP gene activation was paralleled by TIMP-2 gene activation. However, only MMP-9 mRNA expression was significantly enhanced by the gingipain-null mutant. At 8 and 24 h post-infection, P. gingivalis increased significantly the MMP-9 protein level compared to the uninfected EHOM model. The present study reports the ability of P. gingivalis to regulate MMP and TIMP production by oral cells, a phenomenon that may contribute to tissue destruction.

Impact of the Distinct Sampling Area on Volumetric Features of Gingival Crevicular Fluid

BACKGROUND

Volumetric features of gingival crevicular fluid (GCF) are under the influence of many factors, including sampling variables. Standardizing such factors may enable a more precise methodology. Thus, analysis of the possible impact of the clinical periodontal status and the distinct location of sampling sites on fluid volume was performed.

METHODS

Clinical parameters were recorded, and fluid samples were obtained from 931 maxillary sites. The potential site-specific volumetric differences among healthy, gingivitis, and periodontitis sites; between multirooted or single-rooted teeth and mesio-buccal or disto-buccal sampling sites; and the correlations between volume and clinical measures were statistically analyzed.

RESULTS

Although volume increased in a disease-related pattern (healthy < gingivitis < periodontitis; P <0.05), the distribution range of volume was widespread, with prominent overlaps between the different clinical periodontal conditions. Multirooted teeth presented more fluid volume, and even mesio-buccal or disto-buccal sites exhibited some volumetric differences (P <0.05). Constant correlations between volume and clinical parameters could be observed only at gingivitis sites (P <0.05).

CONCLUSIONS

The spectrum of fluid volume is disease related in general. However, the wide range of volumetric distribution, the site-specific nature, and the clear impact of the distinct sampling site on volume are important volumetric features of this biologic fluid. Whenever possible, standardization of the extent of probing depth, degree of gingival inflammation, and distinct sampling area is likely to improve the reliability of GCF methodology.

Gingival crevicular fluid matrix metalloproteinase (MMP)-7, extracellular MMP inducer, and tissue inhibitor of MMP-1 levels in periodontal disease

BACKGROUND

During periodontal inflammation, matrix metalloproteinases (MMPs) are under the control of several regulatory mechanisms including the upregulation of expression by inducers and downregulation by inhibitors. Our study aimed to examine the levels and molecular forms of MMP-7, tissue inhibitor of MMP (TIMP)-1, and extracellular matrix metalloproteinase inducer (EMMPRIN) in gingival crevicular fluid (GCF) from patients with different periodontal diseases.

METHODS

A total of 80 subjects (20 patients with generalized aggressive periodontitis [GAgP], 20 with chronic periodontitis [CP], 20 with gingivitis, and 20 periodontally healthy subjects) were included in this study. Periodontal status was evaluated by measuring probing depth, clinical attachment loss, presence of bleeding on probing, and plaque. GCF MMP-7, TIMP-1, and EMMPRIN levels and molecular forms were analyzed by enzyme-linked immunosorbent assay (ELISA) and Western immunoblot techniques using specific antibodies.

RESULTS

Total amounts of GCF MMP-7 were found to be similar between the study groups. GAgP, CP, and gingivitis groups had significantly higher total amounts of GCF EMMPRIN compared to healthy subjects (P <0.008). Among the patient groups, the GAgP group had the highest total amount of GCF EMMPRIN relative to the gingivitis group (P = 0.0004). Soluble EMMPRIN existed in GCF in multiple molecular-weight species especially in periodontitis-affected GCF under non-reducing conditions, i.e., 30-, 55-, 100-, 180-, and 200-kDa species. All patient groups had significantly elevated total amounts of GCF TIMP-1 relative to the healthy group (P <0.0001). GAgP and CP groups also had a higher total amount of GCF TIMP-1 compared to the gingivitis group (P <0.0001 and P <0.0001, respectively). The GAgP group had higher GCF TIMP-1 and EMMPRIN levels compared to the CP group, but this elevation did not reach statistical significance.

CONCLUSIONS

Our data indicate that MMP-7 is associated with the innate host defense in periodontal tissues. Increased EMMPRIN and TIMP-1 levels in GCF are associated with the enhanced severity of periodontal inflammation, indicating that these molecules can participate in the regulation of progression of periodontal diseases. To our knowledge, the present study demonstrated the presence of soluble forms of EMMPRIN in GCF of patients with different periodontal diseases for the first time.

Tissue inhibitors of metalloproteinases (TIMPs): their biological functions and involvement in oral disease

Several families of enzymes are responsible for the degradation of extracellular matrix (ECM) proteins during the remodeling of tissues. An important family of such enzymes is that of the matrix metalloproteinases (MMPs). To control MMP-mediated ECM breakdown, tissue inhibitors of metalloproteinases (TIMPs) are able to inhibit MMP activity. A disturbed balance of MMPs and TIMPs is found in various pathologic conditions, such as cancer, rheumatoid arthritis, and periodontitis. The role of MMPs in pathology has been extensively described in the literature. The main focus of this review lies in the biological functions of TIMPs and their occurrence in disease, especially in the head and neck area. Their biological functions and their role in diseases like oral cancers and periodontitis, and in the development of cleft palate, will be discussed. Finally, the diagnostic and therapeutical opportunities of TIMPs will be evaluated.

Actinobacillus actinomycetemcomitans lipopolysaccharide regulates matrix metalloproteinase, tissue inhibitors of matrix metalloproteinase, and plasminogen activator production by human gingival fibroblasts: A potential role in connective tissue destructio

Fibroblasts, a major constituent of gingival connective tissue, can produce immunoregulatory cytokines and proteolytic enzymes that may contribute to tissue destruction. In this study, we evaluated the production of matrix metalloproteinases (MMPs), tissue inhibitors of MMPs (TIMPs), and plasminogen activators by gingival fibroblasts stimulated with lipopolysaccharides (LPS) produced by periodontopathogens, including Actinobacillus actinomycetemcomitans. In addition, changes in the expression and phosphorylation state of fibroblast intracellular signaling proteins induced by A. actinomycetemcomitans LPS were characterized using antibody microarrays. We showed that A. actinomycetemcomitans LPS induced the production of a 50 kDa plasminogen activator, MMP-2 and, to a lesser extent, MMP-3 by fibroblasts. The stimulation of fibroblasts with A. actinomycetemcomitans LPS also resulted in the overproduction of TIMP-1, but had no effect on the production of TIMP-2. Comparable responses were also obtained with Porphyromonas gingivalis and Fusobacterium nucleatum subsp. nucleatum LPS. The results of the microarray analyses showed that A. actinomycetemcomitans LPS induced changes in the phosphorylation state and expression of gingival fibroblast intracellular signaling proteins. More specifically, they suggested that A. actinomycetemcomitans LPS may induce both Jun N-terminus protein-serine kinases (JNK) and mitogen-activated protein-serine kinase p38 alpha (p38alpha MAPK) pathway activation, leading to increased activator protein-1 (AP-1) and nuclear factor kappa-B (NFkappaB) activities, which in turn can stimulate MMP-2, MMP-3, TIMP-1, and urokinase-type plasminogen activator (uPA) expression. This may contribute to periodontal connective tissue destruction.

The role of matrix metalloproteinases in the oral environment

This review focuses specifically on matrix metalloproteinases (MMPs) and their role in physiological and pathological extracellular matrix (ECM) remodeling and degradation processes in the oral environment. A group of enzymes capable of degrading almost all ECM proteins, MMPs contribute to both normal and pathological tissue remodeling. The expression of different MMPs may be upregulated in pathological conditions such as inflammation and tumor invasion. The balance between activated MMPs and tissue inhibitors of metalloproteinases (TIMPs) controls the extent of ECM remodeling. Prior to mineralization, MMPs may participate in the organization of enamel and dentin organic matrix, or they may regulate mineralization by controlling the proteoglycan turnover. There is evidence indicating that MMPs could be involved in the etiology of enamel fluorosis and amelogenesis imperfecta. They seem to play a part in dentinal caries progression, since they have a crucial role in dentin collagen breakdown in caries lesions. MMPs have been identified in pulpal and periapical inflammation and are strongly correlated with periodontal diseases, since they are the major players in collagen breakdown during periodontal tissue destruction. The use of MMP inhibitors could help the prevention and treatment of many MMP-related oral diseases.

Matrix metalloproteinase-13 is highly expressed in destructive periodontal disease activity

BACKGROUND

Matrix metalloproteinases (MMPs) participate in extracellular matrix degradation in physiological and pathological conditions. The available evidence suggests that MMP-13 plays a significant role in both the initiation and progress of bone resorption. The aim of our study was to identify the presence of MMP-13 in adult patients with untreated chronic periodontitis. We also determined the activity of MMP-13 present in lesions undergoing episodic attachment loss in gingival crevicular fluid (GCF) samples.

METHODS

After monitoring at 2 and 4 months, 21 patients showed destructive periodontitis (periodontally affected sites presenting at least two sites with > or =2 mm clinical attachment loss), and GCF samples were collected both from active and inactive sites (21 GCF samples, each). GCF was collected during a 30-second interval using a paper strip, and an immunofluorescence assay was performed to determine the basal activity of MMP-13 and the relationship between 4-aminophenylmercuric acetate (APMA)-activated total MMP-13 and basal MMP-13 activity. Gingival tissues from five patients were fixed in formalin and MMP-13 expression was demonstrated using immunohistochemistry and in situ hybridization. MMP-13 molecular forms were examined by Western immunoblotting with monoclonal antibodies.

RESULTS

MMP-13 was found in 100% of GCF samples from patients with chronic periodontitis. Active sites, associated with tissue destruction, had significantly higher proportions of active MMP-13 and MMP-13 activity levels than their inactive counterparts (1.49 versus 1.17 ng fluorescent product, respectively; P <0.05). Western blot, immunohistochemical staining, and in situ hybridization confirmed the presence of MMP-13 in periodontal disease, with observable differences between periodontitis and healthy subjects. MMP-13 immunoreactivities were seen mainly as 55 and 48 kDa, corresponding to partially and fully activated forms, respectively, and a smaller proportion of 60-kDa proenzyme form.

CONCLUSION

MMP-13 activity in GCF samples was significantly increased in active sites from progressive periodontal disease, supporting its role in the alveolar bone loss developed in this disease.

Soft tissue reactions to bioactive glass 13-93 combined with chitosan

The aim of this study was to evaluate rabbit soft tissue reactions to bioactive glass 13-93 mesh by using a histological and immunohistochemical analysis. Bioactive glass (13-93) mesh fixed with 3 wt % chitosan was implanted into the dorsal subcutaneous space of New Zealand White rabbits (n=18) for six, 12, and 24 weeks, respectively. After 6 weeks the bioactive glass remnants were surrounded by foreign-body granuloma with eosinophilic granulocytes. After 12 and 24 weeks the implanted material was mainly absorbed, but, if any particles still remained the foreign-body reaction was notably milder. Yet, a mild chronic inflammatory infiltrate was present. Matrix metalloproteinase (MMP) -2, -3, -13 and tissue inhibitory protein (TIMP-1 and -2) expressions were studied by immunohistochemistry. MMP-3, -13, TIMP-1, and -2 positivity were detected throughout the follow-up period. MMP-2 positivity was only occasionally seen in the 24 week samples, which is constitutively expressed but is not related to inductive MMP-3 and -13 cascade. The presence of eosinophilic granulocytes in some of the samples raises the possibility of an allergic reaction to the materials. MMP-3 and -13 are suggested to participate in the host reaction to either bioactive glass or chitosan.

Matrix metalloproteinases, tissue inhibitor of matrix metalloproteinase-1, and laminin-5 gamma2 chain immunolocalization in gingival tissue of endotoxin-induced periodontitis in rats: effects of low-dose doxycycline and alendronate

BACKGROUND

Matrix metalloproteinases (MMPs) play important roles in tissue destruction mechanisms of periodontitis. MMP-8 and -13 are the major collagenases that act in extracellular matrix degradation in periodontal tissues. MMP-14 is a membrane-type MMP, and laminin (Ln)-5 is a basal membrane component. The aim of the present study was to evaluate the effects of doxycycline and alendronate on gingival tissue expression of MMP-8, -13, and -14; tissue inhibitors of MMP (TIMP)-1; and Ln-5 gamma2 chain in experimental periodontitis induced by Escherichia coli endotoxin (LPS) in rats.

METHODS

Experimental periodontitis was induced by repeated injection of LPS. Forty-four adult male Sprague-Dawley rats were divided into five study groups: saline control, LPS, LPS + doxycycline, LPS + alendronate, and LPS + doxycycline + alendronate. Doxycycline and alendronate were given as a single agent or as combination therapy during the 7 days of the experimental study period. On day 7, the rats were sacrificed, and the gingival tissues were analyzed immunohistochemically for expression of MMP-8, -13, and -14, Ln-5 gamma2 chain, and TIMP-1. Alveolar bone loss was evaluated morphometrically under a stereomicroscope. Data were tested statistically by Kruskal-Wallis and Mann-Whitney tests and Spearman correlation analysis.

RESULTS

Alveolar bone loss was significantly higher in the LPS, doxycycline, alendronate, and combination groups than in the saline control group (all P <0.01). MMP-8 expression was significantly higher in the LPS group than in the saline control group (P = 0.001). Individual administration of doxycycline or alendronate significantly decreased the expression of MMP-8 compared to LPS (P = 0.01). Combined drug administration reduced MMP-14 significantly compared to doxycycline (P = 0.004). No significant differences in Ln-5 gamma2 chain expression were found between the study groups (P >0.05). MMP-14 significantly correlated with the Ln-5 gamma2 chain in the LPS + alendronate group (P = 0.04) and with the amount of alveolar bone loss in the LPS + doxycycline + alendronate group (P = 0.03).

CONCLUSIONS

Our findings suggest that alendronate and/or doxycycline may inhibit MMP-8 expression significantly; particularly, their combined administration may provide beneficial effects in periodontal treatment. Moreover, individual administration of alendronate and doxycycline results in significant increases in TIMP-1 expression in gingiva. However, these effects of combined low-dose doxycycline and alendronate on MMPs and TIMP should be verified by clinical human trials before these agents are used in dental practice.

Salivary matrix metalloproteinase-8 in patients with and without coronary heart disease may indicate an increased susceptibility to periodontal disease

BACKGROUND AND OBJECTIVE

Tissue destruction caused by periodontitis may increase the number of cytokines implicated in the pathogenesis of cardiovascular diseases. We measured the concentration of the leukocyte-derived proteolytic enzyme, salivary neutrophil collagenase-2 [matrix metalloproteinase-8 (MMP-8)], as a marker of periodontal disease and assessed its relationship to coronary heart disease (CHD). Our aim was to study whether salivary MMP-8 levels were different among patients with and without CHD. The hypothesis was that patients with heart disease might present higher salivary MMP-8 levels than cardiologically healthy controls.

MATERIAL AND METHODS

Saliva samples were taken from 256 patients with CHD and from 250 matched controls with known oral and general health status. The MMP-8 levels in saliva were analyzed by immunofluorometric assay, salivary albumin was assessed by enzyme-linked immunosorbent assay (ELISA) and total protein was determined using the colorimetric method. We further investigated the molecular forms and isoform distribution of salivary MMP-8 by western immunoblotting. The MMP-8 results were adjusted for the number of teeth and salivary protein concentrations.

RESULTS

The adjusted logarithmic MMP-8 values were 0.145 +/- 0.245 microg/l in patients with CHD and 0.088 +/- 0.115 microg/l in controls (p < 0.01). The respective MMP-8 : total protein and MMP-8 : albumin ratios were also significantly higher in CHD patients than in non-CHD subjects.

CONCLUSION

Elevated salivary MMP-8 levels seemed to associate with CHD, suggesting more tissue breakdown as a result of periodontitis among the patients with heart disease.

Association of Matrix Metalloproteinase-9 Promoter Gene Polymorphism With Chronic Periodontitis

BACKGROUND

Matrix metalloproteinases (MMPs) are related to tissue destruction and remodeling events in periodontal diseases. A single nucleotide polymorphism in the promoter region of human MMP-9 gene is associated with the risk of some inflammatory diseases. Therefore, the aim of this study was to investigate the association between MMP-9 promoter polymorphism and severe generalized chronic periodontitis in a Turkish population.

METHODS

Samples of venous blood and DNA were obtained from 70 severe generalized chronic periodontitis patients and 70 healthy subjects. The alleles of the C/T polymorphism at position -1562 in the promoter region of the MMP-9 gene were distinguished by cutting with the SphI restriction enzyme. Genotype and allele frequencies were calculated, and data were analyzed by the chi2 test.

RESULTS

There was a significant difference in MMP-9 genotypes between chronic periodontitis patients and healthy controls. The odds ratios for the CT genotype and the combination of CT and TT genotypes were 0.4 (95% confidence interval, 0.17 to 0.93; P=0.02) and 0.37 (95% confidence interval, 016 to 0.85; P=0.01) relative to the subjects with the CC genotype, respectively.

CONCLUSION

MMP-9 promoter gene polymorphism seems to be associated with severe generalized chronic periodontitis.

Response of human macrophage-like cells to stimulation by Fusobacterium nucleatum ssp. nucleatum lipopolysaccharide

Monocytes/macrophages are key members of the innate immune system and are present in higher numbers in active periodontal lesions than in inactive sites. The aim of this study was to characterize the response of human monocyte U937 cells, differentiated into adherent macrophages by treatment with phorbol-12-myristate 13-acetate, to stimulation by Fusobacterium nucleatum ssp. nucleatum lipopolysaccharide. Attachment of (3)H-lipopolysaccharide to macrophage-like cells was partially inhibited by anti-CD14 and anti-TLR4 polyclonal antibodies. Fusobacterial lipopolysaccharide did not cause cell apoptosis or block apoptosis induced by camptothecin. Lipopolysaccharide up-regulated the secretion of the pro-inflammatory cytokines interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha as well as the chemokine interleukin-8 by macrophage-like cells. In addition, it increased phospholipase C and D activities, which likely contributed to the high levels of prostaglandin E(2) detected in the cell culture supernatant. Lastly, the amount of matrix metalloproteinase-9 produced by macrophage-like cells was significantly increased by the lipopolysaccharide treatment. Interestingly, fusobacterial cells acquired matrix metalloproteinase-9 activity following incubation in the presence of the culture supernatant of lipopolysaccharide-stimulated macrophage-like cells. In summary, the lipopolysaccharide of F. nucleatum ssp. nucleatum has a large array of biological effects on macrophage-like cells. This monocytic responsiveness to lipopolysaccharide may be a key regulator of periodontitis.

Porphyromonas gingivalis-epithelial cell interactions in periodontitis

Emerging data on the consequences of the interactions between invasive oral bacteria and host cells have provided new insights into the pathogenesis of periodontal disease. Indeed, modulation of the mucosal epithelial barrier by pathogenic bacteria appears to be a critical step in the initiation and progression of periodontal disease. Periodontopathogens such as Porphyromonas gingivalis have developed different strategies to perturb the structural and functional integrity of the gingival epithelium. P. gingivalis adheres to, invades, and replicates within human epithelial cells. Adhesion of P. gingivalis to host cells is multimodal and involves the interaction of bacterial cell-surface adhesins with receptors expressed on the surfaces of epithelial cells. Internalization of P. gingivalis within host cells is rapid and requires both bacterial contact-dependent components and host-induced signaling pathways. P. gingivalis also subverts host responses to bacterial challenges by inactivating immune cells and molecules and by activating host processes leading to tissue destruction. The adaptive ability of these pathogens that allows them to survive within host cells and degrade periodontal tissue constituents may contribute to the initiation and progression of periodontitis. In this paper, we review current knowledge on the molecular cross-talk between P. gingivalis and gingival epithelial cells in the development of periodontitis.

Gingival crevicular fluid levels of calprotectin and myeloperoxidase during therapy for generalized aggressive periodontitis

BACKGROUND

Levels of the inflammation marker calprotectin in gingival crevicular fluid correspond to clinical and biochemical parameters of periodontal inflammation. Neutrophil granulocytes (polymorphonuclear neutrophils: PMNs) are supposed to be the main source of calprotectin in gingival crevicular fluid, but evidence is still lacking. The influence of periodontal therapy on gingival crevicular fluid levels of calprotectin has not yet been determined.

OBJECTIVES

Gingival crevicular fluid levels of calprotectin were monitored during therapy for generalized aggressive periodontitis. Interrelations between calprotectin and the PMN marker myeloperoxidase (MPO) were evaluated.

MATERIAL AND METHODS

Gingival crevicular fluid samples were collected from 23 patients with generalized aggressive periodontitis before and 3 months after non-surgical therapy with an adjunctive antimicrobial medication. Clinical parameters were recorded with a pressure-calibrated electronic probe. Levels of calprotectin and MPO in gingival crevicular fluid were analysed by enzyme-linked immunosorbent assay (ELISA) procedures.

RESULTS

At baseline, levels of calprotectin and MPO were highly correlated. Bleeding and suppurating sites showed significantly higher levels of calprotectin and MPO than non-bleeding, non-suppurating sites. Therapy significantly decreased levels of both biomarkers. These changes of calprotectin and MPO were highly correlated and also related to probing-depth reduction. Three months after therapy, the levels of both markers still showed significant correlations in initially deep sites, whereas in initially shallow sites no significant correlation was found. After therapy, levels of markers in bleeding and non-bleeding sites were comparable.

CONCLUSION

The correlations between calprotectin and MPO indicate that PMNs are a major contributor to the calprotectin content in gingival crevicular fluid of severely affected sites. Calprotectin levels in gingival crevicular fluid and their changes reflect periodontal inflammation as well as the clinical treatment outcome. A prognostic potential of this marker substance remains to be determined.

Gingival Crevicular Fluid Matrix Metalloproteinase-25 and -26 Levels in Periodontal Disease

BACKGROUND

Tissue destruction associated with the progression of periodontal disease is caused by a cascade of host and microbial proteolytic enzymes. Host-derived matrix metalloproteinases (MMPs) play an important role in the degradation of the extracellular matrix. Leukolysin/membrane-type 6 (MT-6)/MMP-25, the latest member of the MT-MMP subgroup of the MMP family, is primarily expressed by neutrophils and involved in extracellular matrix turnover. Matrilysin-2/MMP-26 (endometase), a novel member of the matrilysin subgroup of the MMP family, can degrade the extracellular matrix, alpha1-antitrypsin, and activate pro-MMP-9. Our study aimed to examine the levels, molecular forms, and degrees of activation of MMP-25 and MMP-26 in gingival crevicular fluid (GCF) from patients with different periodontal diseases.

METHODS

A total of 105 subjects, 35 with generalized aggressive periodontitis (GAgP), 29 with chronic periodontitis (CP), 20 with gingivitis, and 21 periodontally healthy subjects, were included in this study. Periodontal status was evaluated by measuring probing depth, clinical attachment loss, presence of bleeding on probing, and plaque. GCF MMP-25 and MMP-26 levels were analyzed by computer-quantitated Western immunoblotting using specific antibodies.

RESULTS

The 57-kDa soluble pro-MMP-25 and 45- to 47-kDa active form of MMP-25 were detected by Western immunoblots in CP and GAgP GCF, and lesser levels of these soluble MMP-25 immunoreactive bands were detected in gingivitis GCF. An enhanced and similar degree of MMP-25 activation was found in GAgP, CP, and gingivitis groups. There were no detectable MMP-25 immunoreactivities in the healthy subjects' GCF. GAgP and CP groups had elevated GCF MMP-26 levels and degrees of activation compared to the gingivitis and healthy groups (P <0.008). The gingivitis group had higher GCF MMP-26 levels and degree of activation compared to the healthy group (P <0.008).

CONCLUSIONS

The present study demonstrated the presence of soluble or shed forms of MMP-25 and MMP-26 in GCF of patients with different periodontal diseases. Increased levels and activation of MMP-25 and MMP-26 in GCF are associated with an enhanced severity of periodontal inflammation, suggesting that these novel MMPs can participate in the progression of periodontal diseases. They may prove to be diagnostically useful and could be targets of medication in the future.

Collagen degradation by interleukin-1beta-stimulated gingival fibroblasts is accompanied by release and activation of multiple matrix metalloproteinases and cysteine proteinases

OBJECTIVE

Several collagenolytic matrix metalloproteinases (MMPs) have recently been identified in gingival fibroblasts, while secreted cysteine proteinases could also participate in connective tissue destruction in periodontitis. To clarify their involvement, we examined enzyme release during collagen breakdown by cultured cytokine-stimulated fibroblasts.

MATERIALS AND METHODS

Gingival fibroblasts were derived from four chronic periodontitis patients and cultured on collagen gels in serum-free medium for 1-4 days. Collagenolysis was measured by hydroxyproline release into the medium. Proteinases were assessed by electrophoresis and immunoblotting.

RESULTS

Adding interleukin-1beta resulted in progressive gel breakdown. This was associated particularly with a shift in MMP-1 band position from proenzyme to active enzyme and the appearance of active as well as proenzyme forms of cathepsin B. There was also partial processing of pro-MMP-13 and increased immunoreactivity for active cathepsin L. In addition, both pro-forms and active forms of MMP-8, membrane-type-1-MMP and MMP-2 were present in control and treated cultures.

CONCLUSIONS

Fibroblast MMP-1 was most likely responsible for collagen dissolution in the culture model, while cathepsin B may have been part of an activation pathway. All studied proteinases contribute to extracellular matrix destruction in inflamed gingival tissue, where they probably activate each other in proteolytic cascades.

Capsaicin-induced local elevations in collagenase-2 (matrix metalloproteinase-8) levels in human gingival crevice fluid

BACKGROUND AND OBJECTIVES

Application of capsaicin on alveolar mucosa provokes pain and neurogenic vasodilatation in the adjacent gingiva. Pain-associated inflammatory reactions may initiate expression of several pro-inflammatory mediators. Collagenase-2 (matrix metalloproteinase-8: MMP-8) is the major destructive protease, especially in the periodontitis-affected gingival crevice fluid (GCF). With this background, we wished to study whether capsaicin stimulation of alveolar mucosa can induce changes in the GCF MMP-8 levels.

MATERIAL AND METHODS

For 10 generally and periodontally healthy human volunteers, capsaicin (3%)-moistened filter paper was applied unilaterally to the buccal alveolar mucosa on the anterior maxilla. GCF samples were collected from the tooth at the stimulation site and from several other incisors in the upper jaw. MMP-8 levels and molecular forms in GCF samples were determined by immunofluorometric assay (IFMA) and western immunoblotting, respectively.

RESULTS

Capsaicin stimulation of the alveolar mucosa induced significant local elevations in levels and activation of MMP-8 in GCF of the adjacent teeth. Western immunoblot revealed that both neutrophil- and mesenchymal-type MMP-8 isoforms were elevated and activated, together with 110 kDa high-molecular size MMP-8 species. This capsaicin-evoked MMP-8 elevation lasted several minutes after stimulation. During the experiments, no marked changes occurred in MMP-8 levels in the GCF of distantly located teeth.

CONCLUSIONS

These results suggest that capsaicin-evoked neurogenic gingival inflammation can trigger the expression and activation of MMP-8 in GCF of the adjacent teeth.