Collagenase activity in human saliva

The Role of Matrix Metalloproteinases (MMPs) in Human Caries

The objective of this review is to summarize our understanding of the role of host matrix metalloproteinases (MMPs) in the caries process and to discuss new therapeutic avenues. MMPs hydrolyze components of the extracellular matrix and play a central role in many biological and pathological processes. MMPs have been suggested to play an important role in the destruction of dentin organic matrix following demineralization by bacterial acids and, therefore, in the control or progression of carious decay. Host-derived MMPs can originate both from saliva and from dentin. They may be activated by an acidic pH brought about by lactate release from cariogenic bacteria. Once activated, they are able to digest demineralized dentin matrix after pH neutralization by salivary buffers. Furthermore, the degradation of SIBLINGs (Small Integrin-binding Ligand N-linked Glycoproteins) by the caries process may potentially enhance the release of MMPs and their activation. This review also explores the different available MMP inhibitors, natural or synthetic, and suggests that MMP inhibition by several inhibitors, particularly by natural substances, could provide a potential therapeutic pathway to limit caries progression in dentin.

Protein biomarkers of periodontitis in saliva

Periodontitis is a chronic inflammatory condition of the tissues that surround and support the teeth and is initiated by inappropriate and excessive immune responses to bacteria in subgingival dental plaque leading to loss of the integrity of the periodontium, compromised tooth function, and eventually tooth loss. Periodontitis is an economically important disease as it is time-consuming and expensive to treat. Periodontitis has a worldwide prevalence of 5-15% and the prevalence of severe disease in western populations has increased in recent decades. Furthermore, periodontitis is more common in smokers, in obesity, in people with diabetes, and in heart disease patients although the pathogenic processes underpinning these links are, as yet, poorly understood. Diagnosis and monitoring of periodontitis rely on traditional clinical examinations which are inadequate to predict patient susceptibility, disease activity, and response to treatment. Studies of the immunopathogenesis of periodontitis and analysis of mediators in saliva have allowed the identification of many potentially useful biomarkers. Convenient measurement of these biomarkers using chairside analytical devices could form the basis for diagnostic tests which will aid the clinician and the patient in periodontitis management; this review will summarise this field and will identify the experimental, technical, and clinical issues that remain to be addressed before such tests can be implemented.

Salivary proteolytic activities in periodontitis, gingivitis and diabetes mellitus

Elastase activity was found to be significantly increased in periodontitis (0.872±0.4270 absorbance units/mg protein, mean±S. D., 1.05±0.61 units/ml saliva), gingivitis (0.772±0.416 units/mg protein, 1.515±0.952 units/ml) and diabetes (0.549±0.286 units/mg protein, 1.20±0.769 units/ml) compared to normals (0.255±0.089) units/mg protein, 0.264±0.079 units/ml). Chymotryptic activity was not found to be increased in these disease conditions over the normal level (0.284±0.096 units/mg protein). Aminopeptidase activity was elevated only in periodontitis (0.670+0.140 units/mg protein) compared to normals (0.349±0.100 units/mg protein). Trypsin-like activity was also found to be significantly raised in periodontitis compared to normals when Pro-Phe-Arg-p-nitroanilide (0.666±0.204 units/mg protein), Ile-Pro-Arg-p-nitroanilide (1.59±0.260 units/mg protein) and Pyroglu-Pro-Arg-p-nitroanilide (1.82±0.380 units/mg protein) were used as substrates. The normal values with these three substrates were respectively, 0.454±0.110, 1.04±0.231 and 1.15±0.312 units/mg protein. Total protein level in saliva was found to be significantly elevated in gingivitis (209±66.8 mg/dl) and diabetes (204±68.0) compared to normal values (107±20.7). Increase in periodontitis was marginal (127±28.3 mg/dl). Expression of proteolytic activities normalized to protein level was useful in differential diagnosis. Increase in elastase level in saliva is not a specific marker for periodontal diseases.

Human saliva exposure modulates bone cell performance in vitro

Various situations encountered by a clinician during the daily routine including surgical periodontitis therapy, dental implant insertion, or tooth extraction involve the contact of saliva with the jaw bone. However, there are only sparse data concerning the influence of saliva on bone cells. Saliva specimens were incorporated within culture medium and administered to murine MC3T3 osteoblasts, of which the morphology (REM), proliferation (EZ4U), and differentiation (qRT-PCR, alkaline phosphatase activity, extracellular matrix calcification) were assessed. Simultaneously, the composition of saliva media was analyzed with respect to the content of lactoferrin, activities of classical salivary enzymes, and the ability to provoke inflammatory cytokine production (enzyme-linked immunosorbent assay) in MC3T3 osteoblasts. The morphology, proliferation, and expression of differentiation-associated genes were seriously handicapped by saliva contact. Saliva-touched cells exhibited less alkaline phosphatase but normal levels of extracellular matrix mineralization. Saliva-containing culture media featured physiological activities of salivary enzymes and considerable amounts of lactoferrin but almost completely lacked salivary alkaline phosphatase and unspecific proteases. Upon saliva incubation, MC3T3 osteoblasts did not release noteworthy levels of interleukin-1 beta or tumor necrosis factor alpha. Although saliva is generally considered to vitalize oral tissues, this study reveals that it harms osteoblast-like cells more due to the presence of salivary enzymes than by triggering of inflammation. This issue is clinically relevant because it broadens the understanding of the bone cell fate within the rather complex cosmos of the oral cavity thereby providing a basis for clinical decision making and treatment guidelines. It seems to be reasonable to restrict the contact period between saliva and bone.

Oral fluid-based biomarkers of alveolar bone loss in periodontitis

Periodontal disease is a bacteria-induced chronic inflammatory disease affecting the soft and hard supporting structures encompassing the teeth. When left untreated, the ultimate outcome is alveolar bone loss and exfoliation of the involved teeth. Traditional periodontal diagnostic methods include assessment of clinical parameters and radiographs. Though efficient, these conventional techniques are inherently limited in that only a historical perspective, not current appraisal, of disease status can be determined. Advances in the use of oral fluids as possible biological samples for objective measures of current disease state, treatment monitoring, and prognostic indicators have boosted saliva and other oral-based fluids to the forefront of technology. Oral fluids contain locally and systemically derived mediators of periodontal disease, including microbial, host-response, and bone-specific resorptive markers. Although most biomarkers in oral fluids represent inflammatory mediators, several specific collagen degradation and bone turnover-related molecules have emerged as possible measures of periodontal disease activity. Pyridinoline cross-linked carboxyterminal telopeptide (ICTP), for example, has been highly correlated with clinical features of the disease and decreases in response to intervention therapies, and has been shown to possess predictive properties for possible future disease activity. One foreseeable benefit of an oral fluid-based periodontal diagnostic would be identification of highly susceptible individuals prior to overt disease. Timely detection and diagnosis of disease may significantly affect the clinical management of periodontal patients by offering earlier, less invasive, and more cost-effective treatment therapies.

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'.

A one-step sandwich enzyme immunoassay for human matrix metalloproteinase 8 (neutrophil collagenase) using monoclonal antibodies

A one-step sandwich enzyme immunoassay (EIA) system for human matrix metalloproteinase 8 (MMP-8, neutrophil collagenase, EC 3.4.24.7) has been established with a pair of monoclonal antibodies prepared against the zymogen of MMP-8 purified from human neutrophils. MMP-8 in samples simultaneously reacted with both solid-phase and peroxidase-labeled antibodies. Sensitivity of this EIA system was 0.34 micrograms/l (5.7 pg/assay) and linearity was obtained between 0.5 and 500 micrograms/l (8.3-8300 pg/assay). The EIA system recognized both precursor and active forms of MMP-8 but not MMP-8 complexed with tissue inhibitors of metalloproteinases. There was no difference in the MMP-8 levels between the plasma samples from patients with rheumatoid arthritis or osteoarthritis and those from healthy subjects (median 6.2 micrograms/l, range 1.5-28 micrograms/l). However, the level in synovial fluids from patients with rheumatoid arthritis (median 345 micrograms/l, range 84-2860 micrograms/l) was shown to be higher than that from osteoarthritic patients. MMP-8 levels in human whole saliva from patients with periodontal diseases (median 282 micrograms/l, range 0-1420 micrograms/l) were also significantly higher than those from clinically healthy subjects (median 25 micrograms/l, range 0-100 micrograms/l). Immunoreactivity analyses showed that MMP-8 species in normal human plasma exists as a precursor but not as a complex form with tissue inhibitor of metalloproteinases (TIMP)-1 or TIMP-2.

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.

The effect of treatment on the activity of salivary proteases and glycosidases in adults with advanced periodontitis

Enzyme activity in whole saliva of trypsin-like protease, elastase-like protease, general protease, and three glycosidases was measured by colorimetric assays, using synthetic substrates. A study group of 24 adults with advanced periodontitis was compared to a control group of 25 subjects with healthy periodontium. Clinical parameters and levels of enzyme activity were assessed at baseline, after non-surgical periodontal therapy (at 8 months), following the maintenance phase or periodontal surgery (at 15 months), and after the maintenance phase with or without systemic chemotherapy (at 20 months). The mean values of the proteolytic enzymatic activity and the activity of two glycosidases in whole saliva were significantly higher in the study group than in the control group at baseline. After the initial treatment phase at 8 months, all three proteases were reduced significantly, but the glycosidases were still high. After all treatment phases at 20 months, the activity of both the proteases and glycosidases approximated the values of the healthy group. In the saliva samples collected prior to treatment and following non-surgical periodontal therapy, the activity of salivary elastase correlated significantly with the number of deep gingival pockets (PD > or = 6 mm) and with either gingival index (GI) or the percentage of bleeding sites (BOP%). The enzyme activity in whole saliva appears to reflect the status of periodontal health. Salivary elastase shows good potential to serve as a novel adjunct to detect destructive periodontal inflammation and to follow periodontal healing after treatment.

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.

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.

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

The use of saliva as a source of components that may identify subjects at risk of developing destructive periodontitis, or provide markers of disease potential or activity, has been reviewed. It was concluded that bacteria, their constituents or products are unlikely to be rewarding and that host-derived salivary factors such as enzymes cannot identify risk, as deficiency states for these do not exist. Secretory IgA, plasma IgA and IgG isotype levels and specific antibodies may be associated with risk, but probably only if levels fall below those which are protective or a specific antibody response is absent. More work is needed to distinguish between monomeric and dimeric IgA antibodies and to identify IgG antibodies in longitudinal clinical studies. In general, although saliva may prove to be useful as a source of indicators of current disease activity or as a means of assessing responses to treatment, it is unlikely to provide evidence for the existence of risk factors.

Bacterial adhesion to oral tissues: a model for infectious diseases

The majority of bacteria which colonize humans display sharp host and tissue tropisms; consequently, relatively little is known about how they initiate colonization on mucosal surfaces. The mouth has a variety of features which have enabled it to serve as a useful model for the discovery of basic principles of host-parasite interactions occurring in mucosal environments. Early studies demonstrated that indigenous bacteria attach to surfaces of the mouth in a highly selective manner; attachment was often observed to correlate with colonization. These studies led to the recognition that bacterial attachment is an essential step for colonization in environments which contain surfaces exposed to a fluid flow. Bacterial adhesion has subsequently grown into a major area of infectious disease research. Many bacteria have been found to possess proteinaceous components, called "adhesins", on their surfaces which bind in a stereochemically specific manner to complementary molecules, or "receptors", on the tissue surface. Adhesins are often lectins which bind to saccharide receptors, but some adhesins are thought to bind to proteinaceous receptors. Studies of components of human saliva, which adsorb to hydroxyapatite (HA) surfaces similar to those of teeth, and promote the attachment of prominent plaque bacteria, have revealed that the acidic proline-rich proteins (PRPs) promote the attachment of several important bacteria. These include strains of Actinomyces viscosus, Bacteroides gingivalis, some strains of Streptococcus mutans, and others. The salivary PRP's are a unique family of molecules. However, segments of PRPs are structurally related to collagen. This may be significant, since B. gingivalis and certain cariogenic streptococci bind to collagenous substrata, and such interactions may facilitate their invasion into gingival tissues, or into dentin or cementum, respectively. Another unexpected observation was that although A. viscosus and other bacteria bind avidly to PRPs adsorbed onto apatitic surfaces, they do not interact with PRPs in solution. PRP molecules evidently undergo a conformational change when they adsorb to HA, and adhesins of A. viscosus recognize cryptic segments which are only exposed in adsorbed molecules. This provides the bacteria with a mechanism for efficiently attaching to teeth while suspended in saliva. It also offers a molecular explanation for their sharp tropisms for human teeth. It has proven convenient to refer to such hidden receptors for bacterial adhesins as "cryptitopes" (from cryptic, meaning hidden, and topo, meaning place).(ABSTRACT TRUNCATED AT 400 WORDS)