Nature of collagenolytic enzyme and inhibitor activities in crevicular fluid from healthy and inflamed periodontal tissues of beagle dogs

Cortical organoids model early brain development disrupted by 16p11.2 copy number variants in autism

Reciprocal deletion and duplication of the 16p11.2 region is the most common copy number variation (CNV) associated with autism spectrum disorders. We generated cortical organoids from skin fibroblasts of patients with 16p11.2 CNV to investigate impacted neurodevelopmental processes. We show that organoid size recapitulates macrocephaly and microcephaly phenotypes observed in the patients with 16p11.2 deletions and duplications. The CNV dosage affects neuronal maturation, proliferation, and synapse number, in addition to its effect on organoid size. We demonstrate that 16p11.2 CNV alters the ratio of neurons to neural progenitors in organoids during early neurogenesis, with a significant excess of neurons and depletion of neural progenitors observed in deletions. Transcriptomic and proteomic profiling revealed multiple pathways dysregulated by the 16p11.2 CNV, including neuron migration, actin cytoskeleton, ion channel activity, synaptic-related functions, and Wnt signaling. The level of the active form of small GTPase RhoA was increased in both, deletions and duplications. Inhibition of RhoA activity rescued migration deficits, but not neurite outgrowth. This study provides insights into potential neurobiological mechanisms behind the 16p11.2 CNV during neocortical development.

A dynamic view of the proteomic landscape during differentiation of ReNcell VM cells, an immortalized human neural progenitor line

The immortalized human ReNcell VM cell line represents a reproducible and easy-to-propagate cell culture system for studying the differentiation of neural progenitors. To better characterize the starting line and its subsequent differentiation, we assessed protein and phospho-protein levels and cell morphology over a 15-day period during which ReNcell progenitors differentiated into neurons, astrocytes and oligodendrocytes. Five of the resulting datasets measured protein levels or states of phosphorylation based on tandem-mass-tag (TMT) mass spectrometry and four datasets characterized cellular phenotypes using high-content microscopy. Proteomic analysis revealed reproducible changes in pathways responsible for cytoskeletal rearrangement, cell phase transitions, neuronal migration, glial differentiation, neurotrophic signalling and extracellular matrix regulation. Proteomic and imaging data revealed accelerated differentiation in cells treated with the poly-selective CDK and GSK3 inhibitor kenpaullone or the HMG-CoA reductase inhibitor mevastatin, both of which have previously been reported to promote neural differentiation. These data provide in-depth information on the ReNcell progenitor state and on neural differentiation in the presence and absence of drugs, setting the stage for functional studies.

Salivary type I collagen degradation end-products and related matrix metalloproteinases in periodontitis

AIM

Type I collagen degradation end-products and related matrix metalloproteinases (MMPs) were examined aiming to detect potential markers of periodontitis in saliva, with high sensitivity and specificity.

MATERIALS AND METHODS

The salivary concentrations of MMP-8, MMP-9 and MMP-13, tartrate-resistant acid phosphatase serum type 5b, C-terminal cross-linked telopeptide of type I collagen (CTx), N-terminal cross-linked telopeptide of type I collagen (NTx) and cross-linked carboxyterminal telopeptide of type I collagen were analysed in 230 subjects. Oral health examination included panoramic radiography.

RESULTS

The concentrations of MMP-8, MMP-9 and MMP-13 in saliva were higher in subjects with generalized periodontitis than in controls. Of the tested salivary markers, MMP-8 was the only marker capable of differentiating subjects with severe alveolar bone loss from those with slight bone loss (p < 0.001). The association between the salivary MMP-8 levels and periodontitis remained significant after the adjustment with age, gender and smoking. In addition, significant correlations were found between the tested markers and periodontal parameters.

CONCLUSION

Enzymes and end-products of type I collagen degradation have different associations with each other and with periodontal status that may reflect their roles in the cascade leading to alveolar bone loss. MMP-8 is a strong biomarker candidate for detecting alveolar bone destruction.

Membrane type (MT) 1-matrix metalloproteinase (MMP) and MMP-2 expression in ligature-induced periodontitis in the rat

BACKGROUND

Matrix metalloproteinases (MMPs) have been shown to be involved in the degradation of the extracellular matrix (ECM). In particular, MMP-2 and MMP-9 (gelatinase A and gelatinase B, respectively) have been identified as the predominant MMPs during periodontitis. Recent studies have indicated that a novel transmembrane MMP, mebrane-type 1 matrix metalloproteinase (MT1-MMP), can activate pro-MMP-2 in tumor metastasis. This study aims to elucidate the presence and localization of MT1-MMP and MMP-2 in periodontitis in a rat model.

METHODS

In 2 groups of 40-day-old male Sprague-Dawley rats, periodontitis was initiated by ligating floss around maxillary second molars. A group of control animals were left untreated. Maxillary dentoalveolar segments were isolated after 7 and 21 days postinduction and were prepared for gross and radiographic analysis of bone loss and for histological analysis. Samples were also prepared for gel zymography to detect the presence of MMP-2, and for Northern blot analysis and in situ hybridization with MT1-MMP probes.

RESULTS

MMP-2 expression increased at 21 days following ligature placement, in conjunction with MT1-MMP expression. MT1-MMP mRNA expression was observed in epithelial cells, fibroblasts, and in multinucleated cells in the periodontium.

CONCLUSION

Our data suggest that MT1-MMP may play a role in extracellular matrix degradation during periodontitis, in concert with MMP-2 and other proteinases.

Cytokines modulate routes of collagen breakdown. Review with special emphasis on mechanisms of collagen degradation in the periodontium and the burst hypothesis of periodontal disease progression

In this paper, we review recent work on collagen degradation, 2 main routes of breakdown are described and their relevance during healthy and inflammatory conditions of the periodontium is discussed. Special attention is paid to the possible role of cytokines, in particular interleukin 1 (IL-1) and transforming growth factor beta (TGF-beta), on the modulation of collagen phagocytosis and metalloproteinase production. IL-1 has been shown to have a dual function in collagen digestion. It inhibits the intracellular phagocytic pathway, but at the same time, it strongly promotes extracellular digestion by inducing the release of collagenolytic enzymes like collagenase. TGF-beta has an opposite effect on both pathways and antagonizes IL-1. Collagenase is released in an inactive form, and a considerable fraction of the proenzyme may become incorporated in the extracellular matrix. This reservoir of latent enzyme can be activated (for instance by plasmin), leading to a sudden and extensive breakdown of the collagenous fibre meshwork. It is suggested that this phenomenon may also take place during progressive periodontitis and could explain an episodic nature of collagenolysis, clinically resulting in bursts of attachment loss (burst hypothesis).

Periodontal disease diagnosis: current status and future developments

OBJECTIVES

This manuscript attempts to critically review traditional and currently employed methods of periodontal diagnosis, in the light of current knowledge about individual patients and sites at risk of progressive periodontal attachment loss.

DATA SOURCES

Articles published over the last decade from international research journals, have demonstrated that existing methods of periodontal disease diagnosis are seriously deficient with respect to accuracy, their ability to predict ongoing or future disease activity and their ability to determine the current activity status of historically diseased sites.

STUDY SELECTION

Longitudinal studies have questioned the rationale behind traditional treatment regimes and underlined the importance of site-directed therapy to avoid potentially damaging instrumentation of quiescent or healthy sites. The recent explosion in local, less invasive chemotherapies for periodontal disease management has aimed at addressing the site-specific nature of this group of diseases, but the true benefits of such novel therapies cannot be realised until more accurate and specific diagnostic techniques become available.

CONCLUSIONS

The manuscript concludes that the range of clinical information collected by experienced periodontists using currently available technology is probably sufficient to manage mild-to-moderate chronic adult periodontitis. However, those patients at risk from more aggressive attachment loss, and those individuals that appear refractory to traditional therapies, require the development of more accurate diagnostic tests to compliment the revolution in site-specific therapies. A diagnostic model is presented, which attempts to draw together current and future diagnostic methods for managing the majority of periodontal disease types, and it is suggested that current diagnoses should include some assessment of "risk'.

Effect of Porphyromonas gingivalis on epithelial cell MMP-9 type IV collagenase production

Porphyromonas gingivalis is reportedly capable of stimulating the expression of host cell matrix metalloproteinases (MMP), contributing to tissue destruction. However, the impact of this bacterium on specific molecules remains to be determined. In this study, we evaluate the effect of P. gingivalis on regulation of MMP-9 expression in human gingival epithelial cells (HGEC). Various inocula of P. gingivalis were added to cultures of HGEC. The effects of live bacteria, heat-killed bacteria, and outer membrane extract were analyzed. MMP-9 secretion by HGEC was evaluated by enzyme-linked immunosorbent assay. For inocula smaller than one bacterium per cell, the quantity of MMP-9 secreted by HGEC was increased in comparison to control conditions. For inocula from 2.5 to 250 bacteria per cell, an inhibition of MMP-9 secretion in a dose-response fashion was observed, with a maximum reduction (ranging from 80 to 95% in five experiments) at 50 bacteria per cell. Gelatin zymograms confirmed the decrease in MMP-9 secretion. A band of 83 kDa, corresponding to activated enzyme, was present for inocula of 0.5 to 50 bacteria. Inhibition took place without any alteration of epithelial cell viability. Heat-killed bacteria and outer membrane extract also provoked proenzyme activation but did not inhibit MMP-9 secretion. These results demonstrate a direct effect of P. gingivalis on HGEC, suggesting a specific action on the collagen renewal process at the interface between the epithelium and connective tissue.

Matrix metalloproteinases-1 and -8 and TIMP-1 mRNA levels in normal and diseased human gingivae

Interstitial collagenases, including matrix metalloproteinase-1 (MMP-1) and -8 (MMP-8), serve as initiators of extracellular matrix destruction in periodontal disease. Collagenase activities are mainly regulated by tissue inhibitors of metalloproteinases (TIMPs). We tested the effects of inflammation on MMP-1 and MMP-8 gene expression in periodontal disease. To determine the relative abundance of these mRNAs in gingiva, we used a reverse transcription-polymerase chain reaction (RT-PCR) assay. Gingival biopsies were divided into 2 groups; a control group and an inflamed group with severe gingivitis or periodontitis. The MMP-1 mRNA levels were significantly elevated in inflamed gingiva, while the levels of the MMP-8 transcript were not different in the 2 groups and barely detectable by RT-PCR assay. The expression of the TIMP-1 gene was not altered, and remained higher than any of these other genes in both control and diseased gingivae. These results suggest that MMP-1 rather than MMP-8 may play an important role in the initiation of collagen degradation in periodontal disease. However, the possibility remains that MMP-8 plays an important role in periodontal tissue destruction, since the mRNA abundance and not the enzyme activity was assessed.

Influence of gingival crevicular washing on the expression of polymorphonuclear leukocyte membrane receptors before and after periodontal therapy

Extensive data demonstrate that polymorphonuclear leukocytes (PMN) are the predominant cell type involved in periodontal disease and that gingival crevicular fluid constituents are influenced by the inflamed gingiva. The aim of the present study was to evaluate the ability of gingival crevicular washing (GCW) (a dilution of gingival crevicular fluid) from periodontal sites in different clinical conditions of modulating the PMN membrane receptors involved in motility, adhesion and phagocytosis before and after periodontal treatment. 10 patients affected by adult periodontitis (AP) were selected. From each patient, 2 test sites (TS) were chosen on the basis of a probing depth > 5 mm and attachment loss, and 2 control sites (CS) with probing depth < 3 mm without. Modifications of membrane receptor density of PMN from healthy donors incubated with GCW harvested from TS and CS was evaluated using fluorescent probes and flow cytometry. Compared to CS-GCW, TS-GCW before therapy increased the expression of the beta 2 integrin CD11b and the chemotactic receptor for the oligopeptide N-formyl methionyl leucyl phenylalanine (FMLP-R) while it reduced the expression of L-selectin. GCW collected from the same TS after the successful completion of periodontal treatment did not influence PMN receptors, indicating that the clinical improvement paralleled the disappearance of the PMN modulating capability contained in TS-GCW before therapy. In conclusion, the present data illustrate the relevant modifications occurring at PMN membrane in chronic adult periodontitis exerted by GCW obtained by a simple fluid collection technique. Thus, monitoring gingival crevicular fluid PMN activating capability may help disclose the presence of chronic periodontitis and may be useful in assessing successful treatment.

Stimulation of enzyme and cytokine production by methyl mercaptan in human gingival fibroblast and monocyte cell cultures

The volatile sulphur compound methyl mercaptan (CH3SH) is a by-product of protein metabolism and a principal component of oral malodour. This investigation examines the effect of CH3SH on the enzymatic activities of cathepsins B and G and elastase, and on the production by human gingival fibroblasts of two key factors, prostaglandin E (PGE) and cAMP, of the PGE2-cAMP-dependent pathway, which may contribute to the increased production of collagenase and tissue destruction in human periodontal disease. The results demonstrate that CH3SH alone, or in combination with interleukin-1 (IL-1) or lipopolysaccharide, can significantly enhance the secretion of PGE2, cAMP and procollagenase by human gingival fibroblasts. CH3SH also stimulated mononuclear cells to produce IL-1, which can increase cAMP production, and act in synergism with the direct effect of CH3SH on cAMP. CH3SH also significantly enhanced the activity of cathepsin B, moderately suppressed that of cathepsin G, but did not significantly affect elastase. These results provide evidence that CH3SH could be a contributing factor in the enzymatic and immunological cascade of events leading to tissue degradation in periodontal diseases.

Collagenase activity and tissue inhibitor of metalloproteinases-1 (TIMP-1) content in human whole saliva from clinically healthy and periodontally diseased subjects

Total TIMP-1 concentration in whole saliva of periodontally diseased subjects, 137 +/- 67 ng/ml (mean +/- SD), was clearly lower (p < 0.001) than that of clinically healthy subjects, 273 +/- 145, and that of edentulous subjects, 332 +/- 121. On the contrary, both active [1.58 +/- 0.35 units/ml (mean +/- SD)] and total (2.08 +/- 0.25) collagenase activities in TIMP-1-free whole saliva of diseased subjects were significantly higher than the activities (0.14 +/- 0.14 and 0.50 +/- 0.27, respectively) in TIMP-1-free whole saliva of healthy subjects. Most of the total collagenase in whole saliva of healthy subjects consisted of procollagenase, while mainly active collagenase was present in whole saliva from patients with periodontal diseases. Significant reciprocal changes of TIMP-1 and collagenase levels, that is, increase in TIMP-1 concentration and decrease in collagenase activity, were observed after the initial therapy of periodontitis patients.

Effect of proteolytic enzymes on the lysis and growth of oral bacteria

Previous studies have shown increased levels of proteolytic enzymes in affected periodontal sites. The aim of the present investigation was to evaluate the effect of proteolytic environments on the lysis and growth of selected oral bacteria associated with either healthy or diseased periodontal sites. The effect of trypsin, chymotrypsin and proteinase K on cell lysis was determined following incubation with bacteria, whereas the effect of the same proteolytic enzymes on bacterial growth was tested using a disc-plate technique. Overall, gram-positive bacteria appeared to be more resistant to lysis than gram-negative bacteria. The most susceptible bacteria were Actinomyces spp., Eubacterium saburreum, Prevotella intermedia, Capnocytophaga ochracea, Fusobacterium nucleatum, Prevotella loescheii, Treponema denticola and Actinobacillus actinomycetemcomitans. The disc-plate procedure indicated that the growth of Actinomyces spp., E. saburreum, C. ochracea, P. intermedia, P. loescheii, Porphyromonas gingivalis and T. denticola were the most affected, more particularly by chymotrypsin and proteinase K. Interestingly, the growth of F. nucleatum was rather stimulated by proteolytic enzymes. The observations reported in this investigation indicate that specific and general proteolytic activities have the ability to lyse some oral bacterial species and to interfere with their growth. It is suggested that such effects could represent new mechanisms by which the bacterial ecology of subgingival sites may be affected.

Host enzymes in gingival crevicular fluid as diagnostic indicators of periodontitis

Host responses to periodontal infections include the production of several families of enzymes that are released by stromal, epithelial or inflammatory cells. Study of these enzymes in gingival crevicular fluid may lead to insights into pathogenesis and may provide a rational basis for the development of novel diagnostic tests. However, analogous to other diagnostic interventions in dentistry and medicine, validation of host enzymes as diagnostic indicators is dependent on clear-cut demonstrations of the identity of the enzyme, reproducibility, diagnostic accuracy and clinical utility. The enzyme of interest should be readily measured over a broad range of disease severity and in varied clinical settings. Ideally, the enzyme should also be an essential component of proposed pathogenic mechanisms. In this context, the connective tissue matrix degrading enzymes elastase, collagenase and gelatinase are promising because of their apparently central role in periodontal attachment loss and disease progression. Sensitive and specific assays are also available to quantify these enzymes. Other work on enzymes associated with cell death (aspartate aminotransferase, lactate dehydrogenase) and several neutrophil lysosomal enzymes (beta glucuronidase, arylsulphatase, cathepsins) has demonstrated positive associations between enzyme levels and attachment loss and inflammation. While numerous cross-sectional studies have indicated that the levels of hydrolytic enzymes in gingival crevicular fluid parallel the severity of periodontal lesions, there are much less data on reproducibility, diagnostic accuracy and clinical utility in longitudinal studies. As appropriate study design is an essential prerequisite for establishing the efficacy of host enzymes as diagnostic tests, future clinical investigations should include: (1) individuals who would most likely benefit by early diagnosis, i.e., rapidly progressive and recurrent periodontitis cases; (2) longitudinal, cohort study designs to show that attachment loss is temporally linked with large increases in enzyme activity; (3) the use of a battery of tests to overcome intrinsic problems of low predictive values when prevalence of active disease is low. In the final analysis, the utility of host enzymes as diagnostic indicators will need to be examined in randomized controlled trials in which the question is asked: are patients better off as a result of testing?

Characteristics of a protease inhibitor produced by Prevotella intermedia

The characterization of a protease inhibitor produced by a strain of Prevotella intermedia is reported in the present study. The protease inhibitor was secreted into the culture medium during the exponential growth phase and was also present in significant amounts in the periplasmic space. The inhibitor was active against a wide variety of proteolytic enzymes, including the trypsin-like activity of Porphyromonas gingivalis. The inhibitory compound, a heat labile protein, was isolated by non-denaturing preparative polyacrylamide gel electrophoresis, using concentrated culture supernatant as starting material. The exact functions and the ecological roles of the protease inhibitor produced by P. intermedia remain to be determined.

Role of cytokines and inflammatory mediators in tissue destruction

Colonization or emergence of microbial pathogens may result in tissue destruction by activation of one or more of five distinct host degradative pathways (matrix metalloproteinase pathway, plasminogen-dependent pathway, phagocytic pathway, PMN-serine proteinase pathway and osteoclastic bone resorption) or by direct cleavage of extracellular matrix constituents by microbial proteinases. Activation of endogenous destructive pathways may be mediated by immune responses resulting in expression of degradative cellular phenotypes among both immigrant and resident cell populations. In addition, expression of degradative phenotypes may be triggered by direct influences on host cells of microbial products (LPS, enzymes, toxins). A body of evidence suggests that each of these mechanisms involves local production of proinflammatory cytokines and growth factors. The matrix metalloproteinase pathway is centrally involved in dissolution of all unmineralized connective tissues and perhaps in resorption of bone as well. The matrix metalloproteinase family consists of nine or more genetically distinct Zn++ endopeptidases which collectively cleave all of the constituents of the extracellular matrix. Recent studies have uncovered many essential elements of a complex, but still incomplete, regulatory network that governs tissue destruction. Proinflammatory cytokines and growth factors induce signalling pathways several of which are dependent on protein kinase C and result in transient expression of the transcription factors c-jun and c-fos. Initiation of transcription of most matrix metalloproteinase genes requires binding of the transcription factor AP-1 (c-jun/c-fos) to a specific promoter sequence but attainment of maximal transcription rates is dependent on interaction with other promoter elements as well. Several matrix metalloproteinases have been detected in crevicular fluids and tissues of inflamed human gingiva as have the proinflammatory cytokines (IL-1 and TNF-alpha) which regulate their transcription. Although the mere presence of enzymes and cytokines does not necessarily impart function per se, these observations suggest that some level of spatial or temporal linkage exists between metalloproteinase/cytokine expression and gingival inflammation.

Expression of TIMP-1, TIMP-2 and collagenase mRNA in periodontitis-affected human gingival tissue

Collagenolysis in periodontitis is thought to be modulated by the expression of three genes, collagenase, tissue inhibitors of metalloproteinases-1 and -2 (TIMP-1 and -2). We assessed the possible difference in TIMP-1, TIMP-2 and collagenase mRNA levels between gingival samples from patients with periodontitis and those from healthy subjects by reverse transcription-polymerase chain reaction (RT-PCR). This technique allows detection of transcripts from a very small sample quantity. The experiments showed that levels of TIMP-1 and collagenase transcripts relative to beta-actin are significantly higher in the diseased group than in healthy controls (8.11 +/- 0.83 versus 1.38 +/- 0.28% for TIMP-1 and 0.50 +/- 0.10 versus 0.0075 +/- 0.0024% for collagenase, respectively). The difference in TIMP-2 between the two groups (2.91 +/- 0.46 versus 1.84 +/- 0.87%) did not differ. Therefore, the host would have responded to the increase in collagenase level by preferentially producing TIMP-1 against tissue destruction. The differential gene expression of TIMP-1 and TIMP-2 in our study may account for a distinct genetic regulation of TIMP-1 and -2 in vivo.

Matrix metalloproteinases: a review

Matrix metalloproteinases (MMPs) are a family of nine or more highly homologous Zn(++)-endopeptidases that collectively cleave most if not all of the constituents of the extracellular matrix. The present review discusses in detail the primary structures and the overlapping yet distinct substrate specificities of MMPs as well as the mode of activation of the unique MMP precursors. The regulation of MMP activity at the transcriptional level and at the extracellular level (precursor activation, inhibition of activated, mature enzymes) is also discussed. A final segment of the review details the current knowledge of the involvement of MMP in specific developmental or pathological conditions, including human periodontal diseases.

Dissociation of collagenase-tissue inhibitor of metalloproteinases-1 (TIMP-1) complex--its application for the independent measurements of TIMP-1 and collagenase activity in crude culture media and body fluids

Collagenase-tissue inhibitor of metalloproteinases-1 (TIMP-1) complex was prepared from activated collagenase and TIMP-1 purified from culture media of human skin fibroblasts. After having been confirmed to be a complex by zinc chelate chromatography, the complex was demonstrated to dissociate by passage through an anti-TIMP-1 monoclonal antibody-affinity column. On the basis of above evidence, a simple strategy was set up for the independent measurements of TIMP-1 concentration, and both active and total collagenase activities in crude culture media and body fluids.

Gingival crevicular fluid gelatinase and its relationship to periodontal disease in human subjects

Collagenolytic enzymes released by neutrophils are associated with the destruction of periodontium in periodontal diseases. Measurement of these enzymes in gingival crevicular fluid (GCF) could be used to test for periodontal diseases and thereby simplify diagnosis. To test this hypothesis, gelatinase (MMP-9) was analyzed in GCF samples with a simple assay system. GCF was collected by a mouthrinse method from 10 patients with gingivitis (G); 10 well-treated and maintained periodontitis patients (TP) without detectable loss of attachment; and 9 patients with recurrent loss of periodontal attachment (greater than 2 mm) and/or abscess formation (RP). Clinical measurements including tooth mobility (MOB) and gingival attachment level (GAL) were made monthly for a maximum of 10 months. Active and latent forms of gelatinase were measured by a functional assay using gelatin substrate-gel enzymography and the activities were quantified by laser densitometry. Reproducibility analysis demonstrated that the assay (inter-gel, inter-assay, inter-scan) and diurnal variations were small compared to biological variation. The presence of active gelatinase was detected in 97.8% of TP samples, 86.4% of RP samples, but in only 11.4% of G samples. In addition, the mean active gelatinase activity was found to be significantly higher (p less than 0.001) in the RP (71,006 U) than the TP (43,814 U) groups, both of which were higher (p less than 0.001) than the G group (2824 U). During periods of attachment loss, samples from the RP group exhibited a 2-fold increase of mean active gelatinase activity (129,414 U).(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of collagenase and potential transcriptional factors c-fos and egr-1 in periodontal gingival fibroblasts

In view of the important role of fibroblast-type collagenase in the pathogenesis of periodontal disease (PD), we investigated the expression of this metalloproteinase in primary cultures of non-stimulated fibroblasts dissected from gingival tissues of patients with generalized moderate and localized severe chronic adult PD. Enhanced hybridization signals for collagenase RNA were observed in 8/8 PD-cases when compared with equivalent RNA amounts extracted from normal fibroblasts. Since both the proto-oncogene c-fos and the "early growth response" gene egr-1 might be involved in the transcriptional regulation of the collagenase gene expression in vivo, we also compared the relative expression of both potential transcriptional factors with collagenase RNA in the same fibroblast cytoplasmic extracts. Hybridization signals indicated elevated RNA amounts for c-fos in 8/8 PD-cases and for egr-1 in 7/8 PD-cases when compared with the cells from non-inflamed tissue. In periodontitis gingival tissue specimens, immunolocalization of collagenase could be confirmed in fibroblasts, macrophages and epithelial cells in situ. Collagenase label was not widely distributed within the tissues, but concentrated at the interface between epithelium and connective tissue. The data provide the first evidence that gingival fibroblasts producing elevated levels of collagenase RNA amounts express also c-fos and egr-1 indicating a crucial role for both genes in cellular proliferation and collagenase expression in gingival and periodontal tissue destruction in vivo.

Host response tests for diagnosing periodontal diseases

Extensive data collected over the past decade demonstrate clearly that disease-active and disease-inactive periodontal pockets exist, disease progression is infrequent and episodic, and most progression occurs in a small proportion of highly susceptible individuals. Furthermore, traditionally used diagnostic procedures do not identify susceptible individuals nor distinguish between disease-active and disease-inactive periodontal sites. New diagnostic tests based on host response factors that will aid in resolving these problems appear to be possible. Sources of material for use in such tests include gingival crevicular fluid (GCF), blood cells, and blood serum. Of these, components in GCF are most promising, at least in the immediate future. Although more than 40 GCF components have been studied, efforts that attempt to relate the presence and amount of a given component to an independent measure of active disease are very few in number. As a consequence, we do not yet know the potential for most GCF components as the basis of diagnostic tests. Those components that have been documented to associate with active disease as measured by attachment loss of 2 mm or greater include alkaline phosphatase, beta-glucuronidase, prostaglandin-E2, aspartate aminotransferase, and IgG4 antibody subclass. Even in these cases, the data base is small and additional clinical studies are needed to document claims. At the present time, tests based on beta-glucuronidase, nonspecific neutral proteases, and aspartate aminotransferase are being commercialized. One test has received FDA approval. Tests based on blood cells have limited application for patients with adult periodontitis, but are useful for patients with early-onset forms of periodontitis. An abnormality in the leukocyte adherence molecules on the surfaces of neutrophils is diagnostic for generalized prepubertal periodontitis, and defects in chemotactic receptor numbers and in a surface molecule designated as GP110 are found on the neutrophils of most but not all localized juvenile periodontitis patients. Recent data indicate that enhanced unstimulated or stimulated release of PGE2 and Interleukin-1 by peripheral blood monocytes may be an indicator of susceptibility to severe periodontitis. Assessment of the humoral immune response as reflected by serum antibodies to antigens of periodontopathic bacteria shows little promise as the basis for tests diagnostic of site-specific disease activity. However, the capacity of an individual to mount an IgG2 subclass response to carbohydrate antigens may have potential as an indicator of disease susceptibility.

Host mediators in gingival crevicular fluid: implications for the pathogenesis of periodontal disease

During the past few years, a considerable number of studies have examined different aspects of the host response in gingival crevicular fluid (GCF), including the relationship of specific markers to the active phases of periodontal disease. Various indicators of the acute inflammatory response (the lysosomal enzymes beta-glucuronidase and collagenase, the cytoplasmic enzyme aspartate aminotransferase, and the arachidonic acid metabolite PGE2) have been shown to be associated with clinical attachment loss in chronic adult periodontitis in man and experimental periodontitis in animal models. In contrast, the relationship of indicators of the humoral immune response in GCF to active periodontal disease is equivocal. Furthermore, a number of indicators of the cellular immune response have been identified recently in GCF (i.e., Interleukin-1 alpha, IL-1 beta, tumor necrosis factor-alpha), but their relationship to active phases of periodontal disease have not been studied. The polymorphonuclear leukocyte (PMN) is the cellular hallmark of acute inflammation. Evidence from the GCF studies suggests that hyperreactivity of these cells plays a critical role in the active phases of some forms of periodontal disease. Metabolic activation of PMN can be associated with a number of potentially destructive reactions. The major effector mechanism for tissue destruction that can be specifically identified with the PMN is the synergistic effect of the release of PMN proteases and the generation of reactive oxygen metabolites by these cells. Priming of the PMN, where the PMN response is enhanced by agents that do not initiate the response, may be an important mechanism for PMN activation in the crevicular environment; for example, cytokines such as IL-1 beta and TNF-alpha, and lipopolysaccharides released from subgingival Gram-negative bacteria, can serve this function. The hypothesis proposed here argues that in addition to the severe forms of periodontal disease that have been associated with qualitative or quantitative PMN defects, tissue destruction in the periodontum can be observed with hyperreactivity of these cells. These differing conclusions do not create a dilemma, but may represent opposite ends of a balance that is no longer in equilibrium.

Production of trypsin and chymotrypsin inhibitors by oral bacterial isolates

Using an agar-skim milk gel method, over 300 oral bacterial isolates were tested for their ability to produce trypsin or chymotrypsin inhibitor. Eleven bacterial strains, including seven isolates identified as Bacteroides intermedius, were found to inhibit both proteolytic activities. The inhibitory factors of the 11 bacterial strains could be divided into two categories: i) heat-stable and dialysable, and ii) heat-labile and non-dialysable. The protease inhibitor activity of B. intermedius strains, which belongs to the latter category, was found in a membrane fraction as well as in a membrane-free extract. Furthermore, three strains of B. intermedius showed this inhibitory activity in the culture supernatant. In combination with plasma-derived protease inhibitors, the production of these additional protease inhibitors by oral bacteria could protect the host from tissue degradation.

The role of inflammatory mediators in the pathogenesis of periodontal disease

The role of bacteria in the initiation of periodontitis is well-documented and the end result, destruction of the alveolar bone and periodontal connective tissue, is readily observed; but the events occurring between these two points in time remain obscure and are the focus of this paper. Bacteria induce tissue destruction indirectly by activating host defense cells, which in turn produce and release mediators that stimulate the effectors of connective tissue breakdown. Components of microbial plaque have the capacity to induce the initial infiltrate of inflammatory cells including lymphocytes, macrophages, and PMNs. Microbial components, especially lipopolysaccharide (LPS), have the capacity to activate macrophages to synthesize and secrete a wide array of molecules including the cytokines interleukin-1 (IL-1) and tumor-necrosis factor-alpha (TNF-alpha), prostaglandins, especially PGE2, and hydrolytic enzymes. Likewise, bacterial substances activate T lymphocytes and they produce IL-1 and lymphotoxin (LT), a molecule having properties very similar to TNF-alpha. These cytokines manifest potent proinflammatory and catabolic activities, and play key roles in periodontal tissue breakdown. They induce fibroblasts and macrophages to produce neutral metalloproteinases such as procollagenase and prostromelysin, the serine proteinase urokinase-type plasminogen activator (u-PA), tissue inhibitor of metalloproteinase (TIMP), and prostaglandins, u-PA converts plasminogen into plasmin, which can activate neutral metalloproteinase proenzymes, and these enzymes degrade the extracellular matrix components. TIMP inactivates the active enzymes and thereby blocks further tissue degradation. Several amplification and suppression mechanisms are involved in the process. While LPS activates macrophages to produce IL-1, IL-1 is autostimulatory and can therefore amplify and perpetuate its own production. Interferon-gamma (INF-gamma) suppresses autostimulation, but it enhances LPS-induced IL-1 production. PGE2 exerts a control over the whole process by suppressing production of both IL-1 and TNF-alpha. Furthermore, the activated cells produce an IL-1 receptor antagonist that binds to the IL-1 receptor but does not induce the biologic consequences of IL-1 binding. Other cytokines such as transforming growth factor-beta (TGF-beta) suppress production of metalloproteinases and u-PA. Thus the progression and extent of tissue degradation is likely to be determined in major part by relative concentrations and half-life of IL-1, TNF-alpha, and related cytokines, competing molecules such as the IL-1 receptor antagonist, and suppressive molecules such as TGF-beta and PGE2. These molecules control levels of latent and active metalloproteinase and u-PA, and the availability and concentration of TIMP determines the extent and duration of degradative activity.

Identification of polymorphonuclear leukocyte collagenase and gelatinase activities in mouthrinse samples: correlation with periodontal disease activity in adult and juvenile periodontitis

In previous studies, elevations in the levels of active and latent collagenase in gingival crevicular fluid (GCF) have been correlated positively with periodontal disease activity. To provide a simple diagnostic approach for testing collagenolytic activity, the feasibility of using a 3.0 ml water mouthrinse to collect GCF simultaneously from all sites in the mouth was assessed. Patients with adult periodontitis (AP, n = 23) and local juvenile periodontitis (LJP, n = 7) were sampled before periodontal therapy and some (12 AP, 4 LJP) were also assessed longitudinally after scaling and root planing, administration of antibiotics, and following periodontal surgery. Healthy patients (n = 19) were used as controls. The levels of active collagenase, procollagenase, and collagenase inhibitor activity were determined by functional assays and quantitated after SDS-PAGE and fluorography. Gelatinase and progelatinase were assayed by enzymography on gelatin-substrate gels. Active collagenase levels were found to be significantly higher (14- to 20-fold) in AP and LJP patients compared to controls, whereas matrix metalloproteinase activity was not detected in mouthrinses from edentulous patients. Collagenase inhibitor levels were generally low in all groups of subjects tested. Following clinical treatment the levels of active collagenase and gelatinase were reduced; the reduction was significant for active collagenase after tetracycline treatment and scaling in LJP patients. Of the clinical indices recorded (gingival index, plaque index, and pocket depth) there were no significant correlations with enzyme activity but similar trends were observed between the changes in active collagenase and gingival index. In patients with untreated periodontal disease, collagenase occurred predominantly in the active form. N-ethylmaleimide (NEM) and p-aminophenylmercuric acetate (AMPA) were equally effective as activators of the latent collagenase, indicating that the collagenase was derived from PMNs, which were also the source of gelatinase. The results of these studies indicate that measurement of active collagenase and gelatinase in mouthrinse samples is potentially useful in the diagnosis and assessment of periodontal disease activity.

Salivary collagenase. Origin, characteristics and relationship to periodontal health

Saliva collected from subjects with healthy and with diseased periodontium was assayed for collagenase activity by incubation at 25 degrees C with soluble type I, II or III collagen. The degradation products were analyzed by separation in SDS-polyacrylamide gel electrophoresis followed either by protein staining or by exposure of the dried gel to X-ray film in the case of radioactively labeled type I collagen. Collagenase of vertebrate type was detected in the whole saliva of all subjects but not in parotid, sublingual or submandibular fluids. Most of the collagenase was in the soluble fraction of saliva that also contained factors which both activated and inhibited the enzyme. The salivary collagenase resembled the collagenase of human PMNs and gingival sulcular fluid in its molecular size of 70,000 daltons, in its activation by gold thioglucose and in its tendency to degrade types I and II collagens over type III collagen. Before periodontal treatment, the saliva of periodontitis patients had significantly higher collagenase than after treatment. In periodontitis, collagenase existed mainly in the active form, while in the healthy mouths most of the enzyme was latent but could be activated by sulfhydryl reagents or proteolytically with trypsin, and chymotrypsin but not by human plasma kallikrein or plasmin. In some of the samples from untreated periodontitis patients bacterial collagenase may have been present in small quantities. Most of the collagenase in the saliva from all subjects appeared to originate from PMNs entering the oral cavity through the gingival sulcus.

Connective tissue-associated proteins in crevicular fluid: potential markers for periodontal diseases

Tests for periodontal disease that are able to detect both ongoing and future loss of clinical attachment would be valuable assets in determining the diagnosis and treatment of periodontal diseases. We hypothesized that connective tissue-associated proteins could be detected in crevicular fluid and would reflect the biochemical activity of the periodontium in health and disease. To test this hypothesis, crevicular fluid samples obtained from patients with various states of periodontal disease were analyzed for the presence of several connective tissue-associated proteins using a dot blot assay. Two such proteins, osteonectin and N-propeptide alpha I type I collagen, were detected in crevicular fluid samples of patients with periodontal disease. Furthermore, the amount of these proteins detected in crevicular fluid appeared to increase with increased probing depth at the sampled site. These studies indicate that measurements of connective tissue-associated proteins in crevicular fluid may prove to be a valuable tool for diagnosing periodontal diseases.

Microbiota and crevicular fluid collagenase activity in the osseointegrated dental implant sulcus: a comparison of sites in edentulous and partially edentulous patients

The soft tissues adjacent to osseointegrated dental implants (OII) were investigated using clinical, biochemical and microbiological methods. Tooth and implant crevices were compared in 15 partially edentulous patients, examining 28 peri-implant and 19 periodontal sites, and in 6 edentulous patients, examining 13 implant sites. Sites were classified by standard periodontal indices; the crevicular fluid flow determined; crevicular fluid was collected for collagenase assays; and the subgingival bacterial flora was examined and cultured. Differences in clinical parameters were noted in that implants had significantly less keratinized gingiva and deeper probing depths. Crevicular fluid was present in the OII sulcus but the crevicular fluid flow did not differ from that observed from tooth sites either in the partially edentulous or edentulous patients. Tissue collagenase activity and collagenase inhibitor were detected in the implant crevicular fluid and, as in periodontal sites, a strong inverse relationship was found between the levels of active collagenase and collagenase inhibitor. Microbiology included darkfield microscopy, anaerobic culturing for total colony forming unit counts and identification of black pigmented Bacteroides (BPB). Few differences were observed between implants and teeth in partially edentulous patients, indicating that crevices around teeth may act as reservoirs of bacteria which can colonize implant sites. A higher percentage of BPBs and wet spreaders (Capnocytophaga) was noted at partially edentulous implant sites when compared with edentulous implant sites, perhaps reflecting the lower numbers of periodontal pathogens present in edentulous mouths. Overall, the characteristics of implant sulci appear to be similar to periodontal sulci with respect to crevicular fluid flow and microflora.

Antigens released from four oral bacteria in periodontitis

Antigens fractionated from cultures of four oral bacteria were tested for binding of serum IgG, IgA and IgM from patients in early and established phase of periodontitis. Bacteroides gingivalis and A.actinomycetemcomitans released antigens that discriminated between serum from individuals with or without periodontitis. The discriminating antigens ranged from 10 to 43 kDa and included neutral sugar and protein but no lipids. Significantly increased levels of IgG and IgA antibodies to the antigens released from B. gingivalis were detected before bone loss was seen and predicted such disease progression.

Detection of high-risk groups and individuals for periodontal diseases: laboratory markers from analysis of gingival crevicular fluid

Gingival crevicular fluid is regarded as a promising medium for the detection of markers of periodontal diseases activity. The collection protocols are straight forward and non-invasive and can be performed at specific sites of interest in the periodontium. Because the fluid accumulates at the gingival margin, it will contain potential markers derived not only from the host tissues and serum but also the subgingival microbial plaque, and thus an extremely broad range of candidate molecules may be investigated. However, the ability to successfully describe indicators of current disease activity and predictors of future disease is dependent not only upon the choice of the biochemical marker but also on the accurate description of the health status of the sample sites using currently available clinical and radiographic methods. Areas of study which currently show the most promise involve the analysis of host enzyme activities directed against components of the extracellular matrix, the nature of the glycosaminoglycans released into the sulcus and the concentration in gingival crevicular fluid of certain mediators of the inflammatory process, most notably prostaglandin E2.

Initial characterization of a neutral metalloproteinase, active on native 3/4-collagen fragments, synthesized by ROS 17/2.8 osteoblastic cells, periodontal fibroblasts, and identified in gingival crevicular fluid

Analysis of collagenolytic activity in gingival crevicular fluid (GCF) has revealed the presence of an enzyme capable of fragmenting native 3/4- and 1/4-collagen cleavage products generated by collagenase. An enzyme with similar activity was also identified in media conditioned by fibroblasts from rat periodontal ligament and gingiva, and by rat osteoblastic cells (ROS 17/2.8, 17/2A, 17/2B). In culture, the enzyme was secreted in a latent form that could be activated by organomercurials. For further characterization of this novel enzyme (MMP-V), the osteoblast proteinase was partially purified. ROS 17/2.8 conditioned medium was harvested daily and the 25%-60% sat. ammonium sulfate fraction chromatographed on an AcA 54 gel filtration column. Latent forms of MMP-V (apparent Mr approximately 54 k) and collagenase (Mr approximately 54 k) were resolved from gelatinase (Mr approximately 76 k) and two collagenase inhibitors (Mr approximately 62 k, approximately 36 k). Activated MMP-V degraded native 3/4-collagen fragments from collagen types I and II in a step-wise manner and was active on denatured collagen. MMP-V showed a divalent cation requirement, was active at neutral pH, and was inhibited by collagenase inhibitor and fetal bovine serum, but not by serine, thiol, or carboxyl proteinase inhibitors. These properties indicate that MMP-V is a member of the matrix-degrading, neutral-metalloproteinase family of enzymes which include collagenase, gelatinase, stromelysin, and telopeptidase. The enzyme may function in the degradation of collagen fibrils by cleaving proteinase-resistant 3/4-collagen fragments that are stabilized by association with neighboring collagen molecules.