Immunochemical detection of the proteoglycans decorin and biglycan in human gingival crevicular fluid from sites of advanced periodontitis

Comparisons between two biochemical markers in evaluating periodontal disease severity: a cross-sectional study

Background

The purpose of this study was to compare two biochemical markers, which have been previously used to determine the degrees of alveolar bone destruction, in evaluating periodontal disease severity.

Methods

The WF6 epitope of chondroitin sulfate (CS) and the alkaline phosphatase (ALP) levels were determined in gingival crevicular fluid (GCF) samples collected from patients with various degrees of disease severity, including ten patients with gingivitis (50 gingivitis sites) and 33 patients with chronic periodontitis (including gingivitis, slight, moderate, and severe periodontitis sites; n = 50 each), as well as from ten healthy volunteers (50 healthy sites) by Periopaper strips. The levels of CS and ALP were measured by an ELISA and a fluorometric assay, respectively.

Results

The results demonstrated low levels of CS and ALP in non-destructive and slightly destructive periodontitis sites, whereas significantly high levels of these two biomolecules were shown in moderately and severely destructive sites (p < 0.05). Although a significant difference in CS levels was found between moderate and severe periodontitis sites, no difference in ALP levels was found. Stronger correlations were found between CS levels and periodontal parameters, including probing depth, loss of clinical attachment levels, gingival index and plaque index, than between ALP levels and these parameters.

Conclusions

It is suggested that the CS level is a better diagnostic marker than the ALP level for evaluating distinct severity of chronic periodontitis.

Biomechanical adaptation of the bone-periodontal ligament (PDL)-tooth fibrous joint as a consequence of disease

In this study, an in vivo ligature-induced periodontitis rat model was used to investigate temporal changes to the solid and fluid phases of the joint by correlating shifts in joint biomechanics to adaptive changes in soft and hard tissue morphology and functional space. After 6 and 12 weeks of ligation, coronal regions showed a significant decrease in alveolar crest height, increased expression of TNF-α, and degradation of attachment fibers as indicated by decreased collagen birefringence. Cyclical compression to peak loads of 5-15N at speeds of 0.2-2.0mm/min followed by load relaxation tests showed decreased stiffness and reactionary load rate values, load relaxation, and load recoverability, of ligated joints. Shifts in joint stiffness and reactionary load rate increased with time while shifts in joint relaxation and recoverability decreased between control and ligated groups, complementing measurements of increased tooth displacement as evaluated through digital image correlation. Shifts in functional space between control and ligated joints were significantly increased at the interradicular (Δ10-25μm) and distal coronal (Δ20-45μm) regions. Histology revealed time-dependent increases in nuclei elongation within PDL cells and collagen fiber alignment, uncrimping, and directionality, in 12-week ligated joints compared to random orientation in 6-week ligated joints and to controls. We propose that altered strains from tooth hypermobility could cause varying degrees of solid-to-fluid compaction, alter dampening characteristics of the joint, and potentiate increased adaptation at the risk of joint failure.

Solar ultraviolet irradiation induces decorin degradation in human skin likely via neutrophil elastase

Exposure of human skin to solar ultraviolet (UV) irradiation induces matrix metalloproteinase-1 (MMP-1) activity, which degrades type I collagen fibrils. Type I collagen is the most abundant protein in skin and constitutes the majority of skin connective tissue (dermis). Degradation of collagen fibrils impairs the structure and function of skin that characterize skin aging. Decorin is the predominant proteoglycan in human dermis. In model systems, decorin binds to and protects type I collagen fibrils from proteolytic degradation by enzymes such as MMP-1. Little is known regarding alterations of decorin in response to UV irradiation. We found that solar-simulated UV irradiation of human skin in vivo stimulated substantial decorin degradation, with kinetics similar to infiltration of polymorphonuclear (PMN) cells. Proteases that were released from isolated PMN cells degraded decorin in vitro. A highly selective inhibitor of neutrophil elastase blocked decorin breakdown by proteases released from PMN cells. Furthermore, purified neutrophil elastase cleaved decorin in vitro and generated fragments with similar molecular weights as those resulting from protease activity released from PMN cells, and as observed in UV-irradiated human skin. Cleavage of decorin by neutrophil elastase significantly augmented fragmentation of type I collagen fibrils by MMP-1. Taken together, these data indicate that PMN cell proteases, especially neutrophil elastase, degrade decorin, and this degradation renders collagen fibrils more susceptible to MMP-1 cleavage. These data identify decorin degradation and neutrophil elastase as potential therapeutic targets for mitigating sun exposure-induced collagen fibril degradation in human skin.

Arginine and glutamate levels in the gingival crevicular fluid from patients with chronic periodontitis

The objectives of this study were to determine arginine and glutamate levels in the gingival crevicular fluid (GCF) of adult chronic periodontitis patients versus periodontally healthy controls, and to compare two kinds of microdialysis probes: normal and U-shaped probes. The analysis of GCF components was developed to improve the diagnosis of periodontal disease (PD). Proteolysis in the periodontal tissues increases the concentration of amino acids (aa) in the GCF and the levels of these aa may reveal PD features and stages. GCF samples were collected by microdialysis in situ from 5 periodontally affected sites (probing depth >or=5 mm, clinical attachment loss >or=3 mm) in 14 adult chronic periodontitis patients and from 14 adult periodontally healthy controls. Capillary zone electrophoresis coupled to laser induced fluorescence detection was used to measure concentration of arginine and glutamate in the GCF. Data were analyzed statistically by ANOVA and Tukey's post-hoc tests (á=0.05). Arginine concentration was increased (p<0.001) and glutamate concentration was decreased (p<0.001) in chronic periodontitis patients as compared to controls. There were no significant differences (p=0.069) between the normal and U-shaped probes. In conclusion, the increase of arginine and decrease of glutamate concentration in GCF were associated to the presence of periodontitis, and might be used as markers to recognize periodontally susceptible subjects as well as to evaluate the treatment course.

Identification of dentine sialoprotein in gingival crevicular fluid during physiological root resorption and orthodontic tooth movement

Root resorption is an unwanted effect of orthodontic tooth movement. Analysis of dentine proteins in gingival crevicular fluid (GCF) is a potentially safer method of quantifying root resorption compared with conventional radiographic methods. This study aimed to identify and quantify the dentine-specific matrix protein, dentine sialoprotein (DSP), released into GCF during physiological root resorption and orthodontic tooth movement. GCF was collected using micropipettes from 50 second primary molar sites undergoing physiological root resorption in 9- to 14-year olds [coronal group (Rc) with advanced resorption (n = 33) and apical group (Ra) with minimal resorption (n = 17)] and 20 subjects aged 8-14 years with erupted mandibular second premolars (control group). In addition, GCF was collected from 20 patients undergoing treatment with fixed appliances at two time points, immediately prior to orthodontic intervention (T0) and 12 weeks following commencement of fixed appliance therapy (T1). GCF samples were analysed for DSP using an immunoassay and levels semi-quantified using image analysis. To determine differences between the means of the various experimental and control groups, data based on the relative optical density volumes, were statistically analysed using a parametric t-test. DSP was raised in sites that were undergoing physiological resorption compared with the non-resorbing controls (P < 0.05). Notably, DSP was detected in some control samples. There was no difference in DSP levels for the Rc or Ra groups. DSP was also raised in GCF samples of teeth at 12 weeks following commencement of fixed appliance therapy (P < 0.001). The results highlight the potential for measuring DSP in GCF as a biomarker to monitor root resorption. Dentine is likely to be the major source for DSP in GCF, although alternative origins of bone and cementum are possible.

Raised chondroitin sulphate WF6 epitope levels in gingival crevicular fluid in chronic periodontitis

AIM

To determine the levels of chondroitin sulphate (CS) WF6 epitope, recognized by WF6 monoclonal antibody, in gingival crevicular fluid (GCF) from different stages of periodontal disease and healthy periodontium, and to correlate those levels with clinical parameters.

MATERIAL AND METHODS

GCF samples, collected from 389 sites, were analysed for the WF6 epitope levels by the competitive enzyme-linked immunosorbent assay.

RESULTS

The median WF6 epitope level was significantly higher in chronic periodontitis sites (n=185) than in healthy and gingivitis sites (n=204) (p<0.001), whereas the median levels did not significantly differ between healthy (n=65) and gingivitis sites (n=139). The median level in severe periodontitis sites (n=60) was significantly higher than that in moderate periodontitis sites (n=63) (p=0.019). Similarly, the median level in moderate periodontitis sites was significantly higher than that in slight periodontitis sites (n=62) (p=0.001). The WF6 epitope levels significantly correlated with probing depth (r=0.777, p=0.001) and loss of clinical attachment level (r=0.814, p=0.001).

CONCLUSION

Elevated CS WF6 epitope levels in GCF are associated with severity of periodontitis. The WF6 antibody may therefore be clinically applied to monitor disease severity and progression.

Lipopolysaccharide alters decorin and biglycan synthesis in rat alveolar bone osteoblasts: consequences for bone repair during periodontal disease

A prime pathogenic agent associated with periodontitis is lipopolysaccharide (LPS) derived from Porphyromonas gingivalis. This study investigated the effects of P. gingivalis LPS on osteoblasts, which are responsible for alveolar bone repair. Bone cells were obtained from explants of rat alveolar bone chips and cultured with 0–200 ng ml⁻¹ of P. gingivalis LPS. Porphyromonas gingivalis LPS significantly increased cell proliferation and inhibited osteoblast differentiation, as judged by reduced alkaline phosphatase activity. Analysis of biglycan mRNA and protein levels indicated that P. gingivalis LPS significantly delayed the normally high expression of biglycan during the early stages of culture, which are associated with cell proliferation and early differentiation of progenitor cells. In the presence of P. gingivalis LPS, decorin expression by the alveolar bone cells was reduced during periods of culture relating to collagen fibrillogenesis and mineral deposition. Analysis of glycosaminoglycan chains conjugated to these proteoglycans suggested that in the presence of P. gingivalis LPS, dermatan sulfate persisted within the matrix. This study suggests that P. gingivalis LPS influences the expression and processing of decorin and biglycan in the matrix, altering alveolar bone cell activity and osteoblast phenotype development. The consequences of this altered expression in relation to hindering bone repair as part of the cycle of events during periodontal disease are discussed.

Porphyromonas gingivalis gingipains mediate the shedding of syndecan-1 from the surface of gingival epithelial cells

Porphyromonas gingivalis gingipains are thought to be critical virulence factors in periodontitis. Increased serum levels of the soluble ectodomains of surface effectors have been reported to occur during bacterial infections. In the present study, we show that the cell surface proteoglycan syndecan-1 was highly expressed on human gingival epithelial cells. Treatments with P. gingivalis culture supernatants consistently mediated the shedding of syndecan-1 from the surface of epithelial cells. Concomitantly, the amount of soluble syndecan-1 detected in the culture medium increased significantly in a time-dependent manner. However, neither a heat-inactivated supernatant nor a supernatant from a gingipain-deficient mutant had a significant effect on syndecan-1 shedding. Such a shedding process may play an important role in the bacterial invasion of periodontal tissue and the modulation of host defences.

Interleukin-1β–Induced Prostaglandin E2Production by Human Gingival Fibroblasts Is Upregulated by Glycine

BACKGROUND

Human gingival fibroblasts (GFB) may produce prostaglandin E(2) (PGE(2)) in response to proinflammatory cytokines. Elevated concentrations of glycine were previously found in periodontal pockets and saliva of periodontitis patients and, therefore, we aimed to study the influence of glycine on PGE(2) production.

METHODS

Human GFB were cultured in the presence of various concentrations of glycine and/or interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha, and IL-10 and their influence on PGE(2) production was measured. The expression of cyclooxygenases (COX) was analyzed by Western blot and immunocytochemistry.

RESULTS

The PGE(2) production by IL-1beta-stimulated GFB was significantly upregulated by glycine. The effect of glycine on IL- 1beta-induced cell proliferation and PGE(2) production was concentration- dependent, reached a peak at 3 mM, and declined slowly at higher doses. The synthesis of PGE(2) by human GFB cultured in the absence of glycine was significantly inhibited by IL-10 and partially induced in cells cultured with glycine. Glycine had no effect on TNF-alpha-induced PGE(2) production. The IL-1beta-driven PGE(2) synthesis was blocked by indomethacin, a COX-1/COX-2 inhibitor, and by COX-2 inhibitor NS-398. The expression of COX-2 protein was slightly induced by glycine, more evidently by IL-1beta, and mostly enhanced by combined IL-1beta with glycine.

CONCLUSION

Since PGE(2) is a potent stimulator of bone resorption, and production of PGE(2) and COX-2 protein is augmented by glycine, our results strongly suggest that glycine may be involved in the pathogenesis of periodontitis.

Advances in periodontal disease markers

A computer-assisted medline search was conducted to find the relevant articles concerning the periodontal disease markers in gingival crevicular fluid (GCF) and saliva published during the 10-year period from 1993 to July 2003. This review suggests that certain diagnostic uses of saliva and GCF show promise. Although both fluids have been used to evaluate the risk for an individual to develop periodontal disease and to monitor of the host response to periodontal therapy, GCF has the chance of being closely approximated to the periodontal tissues where periodontal disease begins. The enzymes contributed to extracellular matrix (ECM) molecules and non-ECM molecules degradation and markers for polymorphonuclear leukocytes (PMN) activity and influx into the gingival tissue seem to provide valuable information regarding the periodontal disease diagnosis and prognosis. There is also an increasing evidence implicating reactive oxygen species and nitric oxide pathway in the pathogenesis of periodontal diseases. Although promising results have been achieved with the assays evaluating the markers in assessment of periodontal disease status, up to now, none of these tests are used routinely. Further, one commercially available genetic test has been reported to have the potential to be used to predict the periodontal disease, but there are controversial reports on this genetic susceptibility test.

Extracellular matrix metabolites as potential biomarkers of disease activity in wound fluid: lessons learned from other inflammatory diseases?

The new era of pharmacogenetics has identified a potential for individuals to receive customized treatments for a variety of disease states. For such individualized treatments to fulfil their potential, it will be essential for clinicians to be able to monitor disease activity, ideally in a rapid, noninvasive fashion. The accessibility of the skin offers much potential to develop noninvasive tests of metabolic and disease activity for clinical use. Impaired human wound healing in the skin is a chronic inflammatory disorder in which the development of such tests has considerable potential, aiding clinical decision making and monitoring responses to treatment. This review article discusses how studies in other human diseases have highlighted potential biochemical markers (biomarkers) of disease activity in secreted biofluids, as aids to determining disease and metabolic activity within tissues. Using, as examples, lessons learned in the study of disease activity and prognosis of other chronic inflammatory conditions, such as osteoarthritis and periodontal disease, this review highlights the potential of dermal extracellular matrix (ECM) components (collagens, proteoglycans, hyaluronan and glycoproteins) for such uses. The limitations of currently utilized techniques and the concept that analysis of ECM components in wound fluid may represent useful biomarkers of disease activity are also discussed.

A role for decorin in the structural organization of periodontal ligament

Decorin is a small leucine-rich proteoglycan that interacts with several matrix molecules, including various types of collagen and growth factors, and suppresses the growth of neoplastic cells by an epidermal growth factor (EGF) receptor-mediated pathway. Decorin is abundantly expressed in the periodontal connective tissues during development and tissue maintenance. In periodontal disease, which is one of the most common diseases in the human kind, the level of decorin is decreased in the periodontal connective tissue. Abnormal expression of decorin may also associate with certain inherited disorders that involve increased susceptibility to severe periodontal disease in the early childhood. Therefore, we investigated the periodontal tissues of mice with targeted disruption of the decorin gene. Gross and microscopic analyses showed that decorin-deficient mice appeared to have normal tooth development and eruption, and there were no signs of periodontal disease. However, electron microscopic analysis revealed abnormal morphology and organization of the collagen fibrils in the periodontal ligament. The number of periodontal ligament fibroblasts in the decorin-deficient mice was also increased about two-fold as compared with the wild-type mice. In cell culture, ectopic overexpression of decorin in NIH 3T3 fibroblasts or decorin added exogenously to periodontal fibroblasts suppressed cell growth. However, blocking the EGF receptor tyrosine kinase activity did not prevent the decorin-elicited growth suppression in periodontal fibroblasts. Additionally, decorin did not induce a marked increase in the relative expression of p21 mRNA in periodontal fibroblasts. Therefore, decorin appeared to regulate growth of normal periodontal fibroblasts by a mechanism distinct from that reported for neoplastic cells. The findings demonstrate that decorin plays a role in the organization of collagen fibrils and regulates cell proliferation in the periodontal ligament.

Reactive oxygen species: a potential role in the pathogenesis of periodontal diseases

The pathological events leading to the destruction of the periodontium during inflammatory periodontal diseases are likely to represent complex interactions involving an imbalance in enzymic and non-enzymic degradative mechanisms. This paper aims to review the increasing body of evidence implicating reactive oxygen species (ROS), derived from many metabolic sources, in the pathogenesis of periodontal tissue destruction. ROS are generated predominantly by polymorphonuclear leukocytes (PMN) during an inflammatory response and are regarded as being highly destructive in nature. The detection of ROS oxidation products, the elevation of iron and copper ions, which catalyse the production of the most reactive radical species, and the identification of an imbalance in the oxidant/antioxidant activity within periodontal pockets, suggests a significant role for ROS in periodontal tissue destruction. In vitro studies have shown that ROS are capable of degrading a number of extracellular matrix components including proteoglycans, resulting in the modification of amino acid functional groups, leading to fragmentation of the core protein, whilst the constituent glycosaminoglycan chains undergo limited depolymerisation. The identification and characterisation of connective tissue metabolites in gingival crevicular fluid (GCF) resulting from the degradation of periodontal tissues, notably alveolar bone, provides further evidence for a role for ROS in tissue destruction associated with inflammatory periodontal diseases.