Proteoglycans of the periodontium: structure, role and function

Early periodontal wound healing after chlorhexidine rinsing: a randomized clinical trial

OBJECTIVES

This single-center randomized, parallel design, clinical trial with a 2-week follow-up involved patients affected by periodontitis undergoing periodontal surgery. The aim was to evaluate periodontal surgical wound healing with the use of chlorhexidine-based mouth rinses versus an untreated control group.

MATERIALS AND METHODS

Periodontal surgery was performed following a standardized protocol. Patients were randomly prescribed i) chlorhexidine (CHX) + anti-discoloration system (ADS) + hyaluronic acid (HA), ii) CHX + ADS or iii) no treatment (control group). Plaque score, gingival inflammation, and Early Healing Index (EHI), assessing the degree of wound closure and the presence of fibrin and necrosis, were evaluated at 3, 7 and 14 days after surgery.

RESULTS

In total, 33 patients were enrolled. Patients were comparable at baseline for all measured clinical parameters. At 3-days wound healing was significantly improved in all patients treated with CHX + ADS-based mouth rinses with a lower EHI score at the interdental papillae compared with control group (p < 0.01). CHX + ADS + HA group presented improved healing across all time points in terms of EHI, plaque containment, and gingival inflammation when compared to control group (p < 0.01).

CONCLUSIONS

The usage of CHX-ADS following periodontal surgery improved early wound healing, reduced plaque accumulation and gingival inflammation. During the early post-operative period the adjunct of HA further improved soft tissue closure.

CLINICAL RELEVANCE

This study aims at evaluating the response of gingival tissues to mouth rinsing with chlorhexidine and anti-discoloration system (CHX + ADS) or CHX + ADS + hyaluronic acid (CHX + ADS + HA) versus no rinse in terms of healing of the periodontal surgical wound. CHX + ADS mouth rinses enhanced early soft tissue closure after periodontal surgery and contributed to the reduction in plaque accumulation and gingival inflammation. The adjunct of HA may be beneficial especially in the early post-operative period. CHX + ADS administration following periodontal surgery may improve soft tissue healing in the first two post-operative weeks.

Matrix Metalloproteinases in the Periodontium-Vital in Tissue Turnover and Unfortunate in Periodontitis

The extracellular matrix (ECM) is a complex non-cellular three-dimensional macromolecular network present within all tissues and organs, forming the foundation on which cells sit, and composed of proteins (such as collagen), glycosaminoglycans, proteoglycans, minerals, and water. The ECM provides a fundamental framework for the cellular constituents of tissue and biochemical support to surrounding cells. The ECM is a highly dynamic structure that is constantly being remodeled. Matrix metalloproteinases (MMPs) are among the most important proteolytic enzymes of the ECM and are capable of degrading all ECM molecules. MMPs play a relevant role in physiological as well as pathological processes; MMPs participate in embryogenesis, morphogenesis, wound healing, and tissue remodeling, and therefore, their impaired activity may result in several problems. MMP activity is also associated with chronic inflammation, tissue breakdown, fibrosis, and cancer invasion and metastasis. The periodontium is a unique anatomical site, composed of a variety of connective tissues, created by the ECM. During periodontitis, a chronic inflammation affecting the periodontium, increased presence and activity of MMPs is observed, resulting in irreversible losses of periodontal tissues. MMP expression and activity may be controlled in various ways, one of which is the inhibition of their activity by an endogenous group of tissue inhibitors of metalloproteinases (TIMPs), as well as reversion-inducing cysteine-rich protein with Kazal motifs (RECK).

Hyaluronic acid enhances cell migration, viability, and mineralized tissue-specific genes in cementoblasts

BACKGROUND/OBJECTIVES

It has been repeatedly demonstrated that cementum formation is a crucial step in periodontal regeneration. Hyaluronic acid (HA) is an important component of the extracellular matrix which regulates cells functions and cell-cell communication. Hyaluronic acid/derivatives have been used in regenerative periodontal therapy, but the cellular effects of HA are still unknown. To investigate the effects of HA on cementoblast functions, cell viability, migration, mineralization, differentiation, and mineralized tissue-associated genes and cementoblast-specific markers of the cementoblasts were tested.

MATERIALS AND METHODS

Cementoblasts (OCCM-30) were treated with various dilutions (0, 1:2, 1:4, 1:8, 1:16, 1:32, 1:64, 1:128) of HA and examined for cell viability, migration, mineralization, and gene expressions. The mRNA expressions of osteocalcin (OCN), runt-related transcription factor 2 (Runx2), bone sialoprotein (BSP), collagen type I (COL-I), alkaline phosphatase (ALP), cementum protein-1 (CEMP-1), cementum attachment protein (CAP), and small mothers against decapentaplegic (Smad) -1, 2, 3, 6, 7, β-catenin (Ctnnb1) were performed with real-time polymerase chain reaction (RT-PCR). Total RNA was isolated on days 3 and 8, and cell viability was determined using MTT assay on days 1 and 3. The cell mineralization was evaluated by von Kossa staining on day 8. Cell migration was assessed 2, 4, 6, and 24 hours following exposure to HA dilutions using an in vitro wound healing assay (0, 1:2, 1:4, 1:8).

RESULTS

At dilution of 1:2 to 1:128, HA importantly increased cell viability (p < .01). HA at a dilution of 1/2 increased wound healing rates after 4 h compared to the other dilutions and the untreated control group. Increased numbers of mineralized nodules were determined at dilutions of 1:2, 1:4, and 1:8 compared with control group. mRNA expressions of mineralized tissue marker including COL-I, BSP, RunX2, ALP, and OCN significantly improved by HA treatments compared with control group both on 3 days and on 8 days (p < .01). Smad 2, Smad 3, Smad 7, and β-catenin (Ctnnb1) mRNAs were up-regulated, while Smad1 and Smad 6 were not affected by HA administration. Additionally, HA at dilutions of 1:2, 1:4, and 1:8 remarkably enhanced CEMP-1 and CAP expressions in a dilution- and time-dependent manner (p < .01).

CONCLUSIONS

The present results have demonstrated that HA affected the expression of both mineralized tissue markers and cementoblast-specific genes. Positive effects of HA on the cementoblast functions demonstrated that HA application may play a key role in cementum regeneration.

Efficacy of Hyaluronic Acid in Relieving Post-implantation Pain: A Split-Mouth Randomized Controlled Trial

Background

Many patients suffer from some degree of pain following the surgical procedures of dental implantation. The fear of pain may be one reason for postponing such prosthodontic treatments. Many procedures have been suggested to control post-implantation pain. This trial evaluated the effectiveness of using hyaluronic acid (HA) during dental implantation on patients’ perceived pain during the postsurgical soft-tissue healing period.

Methodology

A split-mouth randomized controlled trial (RCT) was conducted. The trial sample consisted of 22 dental implants in 11 patients (five males and six females). Patients were selected from those attending the Department of Oral Medicine at the Faculty of Dentistry, University of Damascus between February 2021 and May 2022. The implants were performed in similar bone quality and density for each patient as the implants were inserted in the same jaw on both sides to ensure the same physiological conditions. The study sample was divided into two groups. The first group (the experimental group) consisted of 11 implants in which the implant site was drilled, following which HA was placed inside the implant site and on the surrounding bone before the flap was returned and sutured. The second group (the control group) comprised 11 implants following the conventional procedure without applying any material to the implant socket. The main outcome measure was pain perception which was assessed using the visual analog scale (VAS). Patients were asked to record their perceived pain on the first, third, and tenth days. Two-sample t-tests were used to detect significant differences.

Results

There were statistically significant differences in the mean pain intensity between the experimental and control groups on the first, third, and tenth days (p < 0.05). The mean values of perceived pain in the control group were 5.68, 1.72, and 0.56 on the first, third, and tenth days, respectively. In comparison, the mean values of perceived pain in the experimental group were 4.52, 1.14, and 0.18 on the first, third, and tenth days, respectively. The maximum perceived pain in the control group was 7.5 on the first day following implantation, whereas the maximum value recorded in the experimental group was 6.5. At the third assessment time (i.e., 10 days following the surgical intervention), the mean values were in the very mild category of pain intensity.

Conclusions

This study showed that applying HA in the implant cavity and on the surrounding bone effectively reduced pain after dental implant surgery in comparison with the control group. Patients had lower mean pain scores at one, three, and ten days following surgery compared to the conventional method. HA is suggested to be an adjunctive method to control postsurgical pain after dental implantation.

Treatment of Intrabony Defects with a Combination of Hyaluronic Acid and Deproteinized Porcine Bone Mineral

Background: this study evaluates the clinical outcomes of a novel approach in treating deep intrabony defects utilizing papilla preservation techniques with a combination of hyaluronic acid (HA) and deproteinized porcine bone mineral. Methods: 23 patients with 27 intrabony defects were treated with a combination of HA and deproteinized porcine bone mineral. Clinical attachment level (CAL), pocket probing depth (PPD), gingival recession (REC) were recorded at baseline and 6 months after the surgery. Results: At 6 months, there was a significant CAL gain of 3.65 ± 1.67 mm (p < 0.001) with a PPD reduction of 4.54 ± 1.65 mm (p < 0.001), which was associated with an increase in gingival recession (0.89 ± 0.59 mm, p < 0.001). The percentage of pocket resolution based on a PPD ≤4 mm was 92.6% and the failure rate based on a PPD of 5 mm was 7.4%. Conclusions: the present findings indicate that applying a combined HA and xenograft approach in deep intrabony defects provides clinically relevant CAL gains and PPD reductions compared to baseline values and is a valid new approach in treating intrabony defects.

Glycosaminoglycans accelerate biomimetic collagen mineralization in a tissue-based in vitro model

Mammalian teeth are attached to the jawbone through an exquisitely controlled mineralization process: unmineralized collagen fibers of the periodontal ligament anchor directly into the outer layer of adjoining mineralized tissues (cementum and bone). The sharp interface between mineralized and nonmineralized collagenous tissues makes this an excellent model to study the mechanisms by which extracellular matrix macromolecules control collagen mineralization. While acidic phosphoproteins, localized in the mineralized tissues, play key roles in control of mineralization, the role of glycosaminoglycans (GAGs) is less clear. As several proteoglycans are found only in the periodontal ligament, it has been hypothesized that these inhibit mineralization of collagen in this tissue. Here we used an in vitro model based on remineralization of mouse dental tissues to determine the role of matrix GAGs in control of mineralization. GAGs were selectively removed from demineralized mouse periodontal sections via enzymatic digestion. Proteomic analysis confirmed that enzymatic GAG removal does not significantly alter protein content. Analysis of remineralized tissue sections by transmission electron microscopy (TEM) shows that GAG removal reduced the rate of remineralization in mineralized tissues compared to the untreated control, while the ligament remained unmineralized. Protein removal with trypsin also reduced the rate of mineralization, but to a lesser extent than GAG removal, despite a much larger effect on protein content. These results indicate that GAGs promote mineralization in mineralized dental tissues rather than inhibiting mineral formation in the ligament, which may have broader implications for understanding control of collagen mineralization in connective tissues.

Core Matrisome Protein Signature During Periodontal Ligament Maturation From Pre-occlusal Eruption to Occlusal Function

The pre-occlusal eruption brings the molars into functional occlusion and initiates tensional strains during mastication. We hypothesized that upon establishment of occlusal contact, the periodontal ligament (PDL) undergoes cell and extracellular matrix maturation to adapt to this mechanical function. The PDL of 12 Wistar male rats were laser microdissected to observe the proteomic changes between stages of pre-occlusal eruption, initial occlusal contact and 1-week after occlusion. The proteome was screened by mass spectrometry and confirmed by immunofluorescence. The PDL underwent maturation upon establishment of occlusion. Downregulation of alpha-fetoprotein stem cell marker and protein synthesis markers indicate cell differentiation. Upregulated proteins were components of the extracellular matrix (ECM) and were characterized with the matrisome project database. In particular, periostin, a major protein of the PDL, was induced following occlusal contact and localized around collagen α-1 (III) bundles. This co-localization coincided with organization of collagen fibers in direction of the occlusal forces. Establishment of occlusion coincides with cellular differentiation and the maturation of the PDL. Co-localization of periostin and collagen with subsequent fiber organization may help counteract tensional forces and reinforce the ECM structure. This may be a key mechanism of the PDL to adapt to occlusal forces and maintain structural integrity.

Commercial Local Pharmacotherapeutics and Adjunctive Agents for Nonsurgical Treatment of Periodontitis: A Contemporary Review of Clinical Efficacies and Challenges

Periodontal infections tend to be site-specific, mostly confined to the periodontal pocket. With the surge of antibiotic-resistant bacteria, the trend is shifting towards other therapeutic modalities, especially locally delivered approaches that include other pharmacotherapeutic drugs and medical devices. This narrative review aimed to provide insights into the clinical efficacy of local drug delivery and adjunctive agents used in nonsurgical management of periodontitis. Electronic (PubMed/MEDLINE, CENTRAL, and EMBASE) and bibliographic searches of past systematic reviews were carried out to identify previous publications on the topic. Only relevant literature and randomized controlled trials published in English were selected. In addition, a literature review was developed based on the selected articles. Experimental drugs or agents were excluded. This review highlights the clinically proven and commercially available therapeutic agents related to the management of periodontal disease with comparisons of their clinical efficacies and challenges. A vast array of commercial local pharmacotherapeutic agents had been clinically tested, but the methodologies and clinical results varied within and between each agent used, causing difficulty in drawing conclusions and providing support to the superiority of one agent over another. Considering the benefit-cost ratio with the modest clinical results, the long-term usefulness of these agents remains debatable.

Diversity and evolution of the parotoid macrogland in true toads (Anura: Bufonidae)

Skin glands in amphibians are either distributed throughout the skin or aggregated in multiglandular structures such as the parotoids typical of most species of Bufonidae. Although many early divergent and derived bufonids lack a discrete parotoid in the postorbital–supratympanic (PoSt) region, they have a great macroscopic diversity in the skin morphology of this region. To understand the origin and evolution of this diversity, in particular of the parotoids, we describe the histomorphology of the skin of the PoSt and dorsal regions in 17 species of bufonids, with or without external evident parotoid, and compare it with previously published descriptions. The survey results in 27 characters that were optimized on a phylogenetic hypothesis of Bufonidae. Our results reveal that the PoSt region has a noteworthy morphological diversity of types of glands, spatial organization and differences in the secretion products. Some morphological characters represent putative synapomorphies of internal clades of Bufonidae and are related to the progressive differentiation towards defined structures (macroglands, parotoids). These morphological results, along with published information on the toxicity of the skin secretions and defensive behaviours in some representative species, allow us to infer possible relationships between these features.

Hyaluronan-CD44 interactions mediate contractility and migration in periodontal ligament cells

The role of hyaluronan (HA) in periodontal healing has been speculated via its interaction with the CD44 receptor. While HA-CD44 interactions have previously been implicated in numerous cell types; effect and mechanism of exogenous HA on periodontal ligament (PDL) cells is less clear. Herein, we examine the effect of exogenous HA on contractility and migration in human and murine PDL cells using arrays of microposts and time-lapse microscopy. Our findings observed HA-treated human PDL cells as more contractile and less migratory than untreated cells. Moreover, the effect of HA on contractility and focal adhesion area was abrogated when PDL cells were treated with Y27632, an inhibitor of rho-dependent kinase, but not when these cells were treated with ML-7, an inhibitor of myosin light chain kinase. Our results provide insight into the mechanobiology of PDL cells, which may contribute towards the development of therapeutic strategies for periodontal healing and tissue regeneration.

Comparisons of the chondroitin sulphate levels in orthodontically moved canines and the clinical outcomes between two different force magnitudes

The aims of this study were to compare the chondroitin sulphate (CS) levels in gingival crevicular fluid (GCF) of moved canines using either 70 or 120 g of orthodontic force, and to compare the rate of tooth movement and the amount of pain between these two force magnitudes. Sixteen patients (6 males and 10 females; aged 16.91 ± 2.99 years), with class I malocclusion, who required orthodontic treatment with first premolar extractions, were recruited. The force magnitudes used to move the maxillary canines distally were controlled at 70 and 120 g on the right and the left sides, respectively. GCF samples were collected with Periopaper(®) strips before and during orthodontic tooth movement. Competitive ELISA with monoclonal antibody was used to measure the CS levels. The distance of tooth movement and the amount of pain assessed by visual analog scale (VAS) scores were evaluated. The medians of CS levels during the loaded period were significantly greater than those during the unloaded period (P < 0.05). The differences between the medians of CS levels of 70 g and 120 g retraction force during each 1 week period were not significant. There was no significant difference in the rates of canine movement between these two force magnitudes. However, using 120 g, the medians of VAS scores were significantly greater than those with 70 g (P < 0.05). Collectively, 70 g retraction force appears to be sufficient and more suitable than 120 g force as it causes no difference in biochemically-assessed bone remodelling activity, the same rate of tooth movement, reduced pain and better comfort.

Luteolin and fisetin inhibit the effects of lipopolysaccharide obtained from Porphyromonas gingivalis in human gingival fibroblasts

Periodontitis is an inflammatory process of infectious origin that affects the gums and, in severe cases, destroys connective tissue, leading to loss of the dental organ. Gram-negative Porphyromonas gingivalis bacteria are recovered from patients with chronic periodontitis. The polysaccharide obtained from these bacteria induces the expression of interleukin (IL)-1 beta, tumor necrosis factor, and IL-6. Flavonoids are molecules that participate in the control of inflammatory processes. We studied the role of the flavonoids fisetin, luteolin, myricetin, and morin in inhibiting the activation of mitogen-activated protein kinase (MAPK) and AKT as well as their role in lipopolysaccharide (LPS)-induced cyclooxygenase-2 (COX-2) transcription. All four of these flavonoids were found to inhibit MAPK and AKT. Fisetin and luteolin blocked the activation of MAPK and AKT to levels below basal levels. All of these flavonoids also blocked LPS-mediated COX-2 expression.

Toll-like receptor 3 activation promotes desensitization of histamine response in human gingival fibroblasts: Poly (I:C) induces histamine receptor desensitization in human gingival fibroblasts

Viruses are associated with the development of periodontal disease, particularly during periods of suppressed cellular immunity. For this reason, we evaluated the hypothesis that viral components regulate the actions of histamine, an important mediator of immune responses. We assessed the effect of Poly (I:C) on histamine-mediated intracellular calcium mobilization in human gingival fibroblasts. Our results show that histamine induces an increase in intracellular calcium concentrations in a dose-dependent manner. This response was blocked when cells were incubated in the presence of Poly (I:C). In addition, phorbol esters, a diacylglycerol analog, mimics the inhibitory actions of Poly (I:C) in response to histamine. The effect of Poly (I:C) was reversed by Stuarosporine (1 μM), GÖ6983 (7 μM), Bisindolylmaleimide (1 μM) [a protein inhibitor (PKC)], and SB 203580 (3 μM) (a p38-MAPK inhibitor). These findings suggest that Poly (I:C) regulates histamine-induced calcium mobilization through activation of PKC and p38.

Chondroitin sulphate (WF6 epitope) levels in peri-miniscrew implant crevicular fluid during orthodontic loading

The aim of this study was to monitor changes in chondroitin sulphate (CS; WF6 epitope) levels in peri-miniscrew implant crevicular fluid (PMICF) during orthodontic loading. Ten patients (seven males and three females; aged 22.0 +/- 3.4 years), who required orthodontic treatment with extraction of all four premolar teeth, participated in the study. Twenty miniscrew implants (used as orthodontic anchorage) were placed, two in each patient, buccally and bilaterally in the alveolar bone between the roots of the maxillary posterior teeth. Sentalloy closed-coil springs (50 g) were used to load the miniscrew implants and to move the maxillary canines distally. During the unloaded period, PMICF samples were collected on days 1, 3, 5, and 7 after miniscrew implant placement and on days 14, 21, 28, and 35 during the loaded period. Clinical mobility assessments of the miniscrew implants were recorded at each visit. The competitive enzyme-linked immunosorbent assay with monoclonal antibody WF6 was used to detect CS (WF6 epitope) levels in the PMICF samples. The differences between the CS (WF6 epitope) levels during the unloaded and loaded periods were determined by a Mann-Whitney U-test. During the loaded period, two miniscrew implants were considered to have failed. The CS (WF6 epitope) levels during the unloaded period ranged from 0.00 to 758.03 ng/ml and those during the loaded period from 0.00 to 1025.11 ng/ml. Medians of CS (WF6 epitope) levels, around 'immobile' miniscrew implants, between the unloaded and loaded periods were not significantly different (P = 0.07). CS (WF6 epitope) levels in PMICF can be detected and may be used as biomarkers for assessing alveolar bone remodelling around miniscrew implants during orthodontic loading.

Activation of ERK1/2 by protein kinase C-alpha in response to hydrogen peroxide-induced cell death in human gingival fibroblasts

Hydrogen peroxide (H(2)O(2)) increases protein tyrosine phosphorylation of numerous proteins in human gingival fibroblasts (HGFs). Two main proteins, with an apparent molecular weight of 44 and 42kDa, were phosphorylated after hydrogen peroxide stimulation of the human gingival fibroblasts. Further analysis identified these two proteins as ERK1/2. Maximum phosphorylation was detected at 10min post-H(2)O(2) treatment. Pretreatment with an MEK inhibitor, PD98059, inhibited H(2)O(2)-stimulated ERK1/2 phosphorylation in a dose-dependent manner. Treatment with H(2)O(2) also induced phosphorylation of protein kinase C-alpha (PKCalpha). Staurosporine, a PKC inhibitor, blocked ERK1/2 phosphorylation induced by H(2)O(2). In addition, H(2)O(2)-induced cell death was prevented by PD98059, SB203580, and calphostin C, which are MEK, p38 and PKC inhibitors, respectively. These results suggest that H(2)O(2) leads to the phosphorylation and activation of ERK1/2 in a PKC-dependent manner. These findings demonstrate that the MAPK signaling pathway plays an active role in mediating the H(2)O(2)-induced decrease in HGF cell viability and ATP depletion.

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.

Comparative35S-sulfate and3H-proline metabolism within the interdental septal bone and adjacent periodontal ligament

Tooth movements require rapid remodeling of the periodontal ligament (PDL) and adjacent alveolar bone. Our objective was to compare the regional metabolism of sulfated-glycosaminoglycans (sGAG) within the PDL and adjacent alveolar bone and compare it to the metabolism of collagenous proteins using radioautographic techniques. Rats were injected with either (3)H-proline or (35)S-sulfate and maxillae were removed at 1, 6, and 12 hr 1-7 days later. Silver grains were counted over the PDL and adjacent alveolar bone and the incorporation and removal rates for each radioisotope were determined. In general, net collagenous protein incorporation and removal were greatest within the distal and net sGAG incorporation and removal were greatest within the mesial compartments of the periodontium. The rate of removal of (3)H-proline was significantly greater within the distal alveolar bone surface than the adjacent PDL at all levels (P < 0.001). In contrast, the rate of removal of (35)S-sulfate was significantly greater in the PDL than within the adjacent mesial surface of the interdental septum at all levels (P < 0.001). The mesial surfaces of the interdental septum had a slower rate of removal of both isotopes than distal surfaces at all levels (P < 0.001). Our data suggest significant regional differences in the metabolism of (35)S-sulfate and (3)H-proline within the PDL and alveolar bone, which likely result from the characteristics of the forces produced by the adjacent teeth and may be a factor in the remodeling of the alveolar wall coincident to tooth movement.

Porphyromonas gingivalis lipopolysaccharide induces shedding of syndecan-1 expressed by gingival epithelial cells

Syndecans are constitutively shed from growing epithelial cells as the part of normal cell surface turnover. However, increased serum levels of the soluble syndecan ectodomain have been reported to occur during bacterial infections. The aim of this study was to evaluate the potential of lipopolysaccharide (LPS) from the periodontopathogen Porphyromonas gingivalis to induce the shedding of syndecan-1 expressed by human gingival epithelial cells. We showed that the syndecan-1 ectodomain is constitutively shed from the cell surface of human gingival epithelial cells. This constitutive shedding corresponding to the basal level of soluble syndecan-1 ectodomain was significantly increased when cells were stimulated with P. gingivalis LPS and reached a level comparable to that caused by phorbol myristic acid (PMA), an activator of protein kinase C (PKC) which is well known as a shedding agonist. The syndecan-1 shedding was paralleled by pro-inflammatory cytokine interleukin-1 beta (IL-1beta), IL-6, IL-8, and tumor necrosis factor alpha (TNF-alpha) release. Indeed, secretion of IL-1beta and TNF-alpha increased following stimulation by P. gingivalis LPS and PMA, respectively. When recombinant forms of these proteins were added to the cell culture, they induced a concentration-dependent increase in syndecan-1 ectodomain shedding. A treatment with IL-1beta converting enzyme (ICE) specific inhibitor prevented IL-1beta secretion by epithelial cells stimulated by P. gingivalis LPS and decreased the levels of shed syndecan-1 ectodomain. We also observed that PMA and TNF-alpha stimulated matrix metalloproteinase-9 secretion, whereas IL-1beta and P. gingivalis LPS did not. Our results demonstrated that P. gingivalis LPS stimulated syndecan-1 shedding, a phenomenon that may be mediated in part by IL-1beta, leading to an activation of intracellular signaling pathways different from those involved in PMA stimulation.

Gingival tissue proteoglycan and chondroitin-4-sulphate levels in cyclosporin A-induced gingival overgrowth and the effects of initial periodontal treatment

OBJECTIVES

Cyclosporin A (CsA) is a potent immunosuppressive drug used in organ transplant patients to prevent graft rejection. CsA-induced gingival overgrowth is one of the side effects of this drug and its pathogenesis is still unclear. The present study was planned to comparatively analyse total proteoglycan (PG) and chondroitin-4-sulphate (C4S) levels in CsA-induced overgrown gingival tissue samples obtained before and after initial periodontal treatment and to compare these findings with the situation in healthy gingiva.

MATERIAL AND METHODS

Gingival tissue samples were obtained from nine patients with CsA-induced gingival overgrowth before and 4 weeks after initial periodontal treatment including oral hygiene instruction and scaling and also from 10 healthy control subjects. Total PG and C4S levels were determined by biochemical techniques. PG levels were analysed using modified Bitter and Muir method. C4S assay was carried out using chondroitin sulphate lyase AC and chondroitin-6 sulphate sulphohydrolase enzymes. The results were tested statistically using non-parametric tests.

RESULTS

All clinical measurements in the CsA-induced gingival overgrowth group demonstrated significant reductions 4 weeks after initial periodontal treatment (p<0.05). There was no significant difference between the levels of baseline total PG in CsA-induced gingival overgrowth and healthy control groups (p>0.05). The gingival tissue levels of PG in CsA-induced gingival overgrowth group decreased significantly 4 weeks after treatment (p=0.043). Gingival tissue C4S levels in the overgrowth group were significantly higher than the healthy control group at baseline (p=0.000). C4S levels of the overgrowth group were significantly reduced after treatment (p=0.033), but these levels were still significantly higher than the healthy control group (p=0.000).

CONCLUSION

The observed prominent increase in gingival tissue C4S levels may be interpreted as a sign of an increase in C4S synthesis in CsA-induced gingival overgrowth. Furthermore, remission of clinical inflammation by means of initial periodontal treatment had a positive effect on tissue levels of these extracellular matrix molecules.

Modulation of extracellular matrix synthesis and alkaline phosphatase activity of periodontal ligament cells by mechanical stress

BACKGROUND

Loss of occlusal function has been reported to induce atrophic changes in the periodontal ligament. It is likely that mechanical stress triggers the biological response of periodontal ligament. However, there have been few reports studying the correlation between mechanical stress of varying magnitude and periodontal ligament cell activities such as extracellular matrix (ECM) synthesis.

OBJECTIVE

The objective of this study is to clarify the influence of the mechanical stress on changes in mRNA expression levels of type I collagen and decorin genes, as well as alkaline phosphatase (ALP) activity in response to mechanical stress of varying magnitude.

METHODS

Bovine periodontal ligament cells were cultured on flexible-bottomed culture plates and placed on the BioFlex Loading Stations. Cells were elongated at 6 cycles/min (5 s on and 5 s off) at each of six levels of stretch (0.2, 1.0, 2.0, 3.0, 10, 18% increase in the surface area of the bottom) for 48 h. We measured mRNA expression levels of type I collagen and decorin genes using quantitative reverse transcription-polymerase chain reaction (RT-PCR), and ALP activity in periodontal ligament cell culture under cyclic mechanical stretching.

RESULTS

Mechanical tensional stress of low magnitude induced the increase of both type I collagen and decorin mRNA expression without changing ALP activity in periodontal ligament cells. Mechanical tensional stress of high magnitude induced the increase of type I collagen and decorin mRNA expression while decreasing ALP activity.

CONCLUSION

These results suggest that different magnitude of tensional force induces different responses from periodontal ligament cells, and that mechanical stress plays an important role in remodeling and functional regulation of periodontal ligament.

Total Proteoglycan and Chondroitin-4- Sulfate Levels in Gingiva of Patients With Various Types of Periodontitis

BACKGROUND

The aim of the present study was to investigate the total proteoglycan (PG) and chondroitin-4-sulfate (C4S) levels in gingival tissue samples obtained from patients with aggressive periodontitis (AgP) and chronic periodontitis (CP) before therapy (baseline) and 1 month after completion of non-surgical periodontal therapy.

METHODS

Gingival tissue samples were obtained from 10 AgP and 10 CP patients before initiation of treatment (baseline) and 1 month after non-surgical periodontal treatment. The control group comprised 10 systemically and periodontally healthy subjects. Total PG and C4S levels were determined by biochemical techniques. PG levels were analyzed using a modified Bitter and Muir method. C4S assay was carried out using chondroitin sulphate lyase AC and chondroitin-6 sulphate sulphohydrolase enzymes. The results were tested statistically using parametric tests.

RESULTS

The clinical periodontal parameters demonstrated significant decreases in the periodontitis groups (P<0.05) after treatment, and there was no significant difference between AgP and CP groups at baseline and after treatment (P>0.05). At baseline, total PG and C4S levels in both of the periodontitis groups were significantly lower than that of the control group (P<0.05). One month after the non-surgical periodontal treatment, total PG levels in the periodontitis groups were comparable to the control group (P>0.05), whereas C4S levels in the AgP group were significantly lower than the other study groups (P<0.05). In the CP group, total PG and C4S levels increased significantly (P = 0.001 and P = 0.006, respectively) after non-surgical periodontal treatment, but they did not increase in the AgP group (P>0.05).

CONCLUSION

The significant increases observed in total proteoglycan and chondroitin-4-sulfate levels after non-surgical periodontal treatment in the CP group but not in the AgP group may suggest that healing patterns differ between the two periodontitis types in terms of PG and C4S composition of extracellular matrix.

Gene Expression of Extracellular Matrix Proteoglycans in Human Cyclosporin-Induced Gingival Overgrowth

BACKGROUND

Gingival overgrowth is one of the side effects associated with the systemic use of cyclosporin A (CsA). In vitro studies on the extracellular matrix of gingival tissues have demonstrated an altered composition, particularly an accumulation of proteoglycans and collagen. We investigated the gene expression of extracellular matrix proteoglycans in CsA-induced gingival tissue alterations.

METHODS

mRNA expression of the proteoglycans perlecan, decorin, biglycan, and versican was analyzed by reverse transcription polymerase chain reaction (RT-PCR) in gingival samples obtained from 12 individuals, six with CsA-induced gingival overgrowth (CsA group) and six with a normal gingiva (control group). The RT-PCR products were subjected to 1% agarose gel electrophoresis containing ethidium bromide and analyzed qualitatively and semiquantitatively by densitometry. Density values were normalized by determining the expression of the housekeeping gene beta-actin in the same sample. Groups were compared by the Student's t test.

RESULTS

Perlecan expression showed a marked increase (54%) in the CsA group compared to the control group (P < 0.01), while no significant differences were observed for the other proteoglycans.

CONCLUSION

CsA-induced gingival overgrowth seems to be associated with increased expression of perlecan, a typical basement membrane proteoglycan, but not decorin, biglycan, or versican.

Analysis of the relationship between the severity of periodontal destruction and proteoglycan metabolism of gingiva and gingival crevicular fluid

BACKGROUND

Although it is well-described that proteoglycans (PGs) are among the major non-collagenous components of the matrix which are degraded during periodontal diseases, the relationship between PG metabolism and seventy of periodontal breakdown, the extent of degradation of PGs together with the resulting end-products, and the elimination pathways of these catabolic end-products is likely to need further clarification.

OBJECTIVE

The main aim of the present study was to analyze the possible impact of severity of periodontal destruction on PG metabolism of gingiva and gingival crevicular fluid (GCF).

MATERIAL AND METHODS

For this purpose, gingiva and GCF samples obtained from patients (n = 45) exhibiting sites (n = 57) with moderate periodontal breakdown (MP) or severe periodontal breakdown (SP) were analyzed for PG metabolism via spectrophotometric determination of uronic acid levels. Gingiva and GCF samples were obtained from the same sites in every patient to analyze the possible relationship between uronic acid content of gingival tissue and GCF.

RESULTS

No significant differences were found in uronic acid levels between sites with MP and SP (p > 0.05). The uronic acid content of GCF and gingiva showed significant overlaps between MP and SP sites and uronic acid levels did not present any constant correlation with the clinical parameters (p > 0.05). In a similar manner, uronic acid content of GCF and gingival tissue was not correlated (p > 0.05).

CONCLUSION

The lack of a significant correlation between the uronic acid content of gingival tissue and GCF may suggest that the passage of PG metabolites from gingiva to GCF is likely to be under the influence of multifactorial interactions rather than being linear. As a general measure of PG metabolism, uronic acid levels do not seem to be related with the severity of periodontal destruction and tend to act as different measures when compared to traditional clinical parameters.

Cloning and expression of alpha-D-glucosidase and N-acetyl-beta-glucosaminidase from the periodontal pathogen, Tannerella forsythensis (Bacteroides forsythus)

Screening a genomic library of Tannerella forsythensis (Bacteroides forsythus), using synthetic substrates conjugated to a fluorogen, 4-methylumbelliferone identified two glycosidase genes, which encode alpha-D-glucosidase and N-acetyl-beta-D-glucosaminidase, respectively. The alpha-D-glucosidase has a Mr of 81,141 and is homologous to an alpha-D-glucosidase from Bacteroides thetaiotaomicron. The N-acetyl-beta-D-glucosaminidase has a Mr of 87,787 and is homologous to an N-acetyl-beta-D-glucosaminidase in Porphyromonas gingivalis W83.

Molecular size distribution analysis of human gingival glycosaminoglycans in cyclosporin- and nifedipine-induced overgrowths

Glycosaminoglycans are thought to accumulate in formative lesions like drug-induced gingival overgrowth. Recent evidences, however, suggest that the amounts of glycosaminoglycans are comparable in overgrown and healthy gingiva. Besides, alterations in the size distribution of glycosaminoglycan molecules isolated from phenytoin-induced overgrown samples have also been suggested. Therefore, we sought to determine possible differences in molecular size distribution of gingival glycosaminoglycans in other types of drug-induced overgrowths. Purified gingival glycosaminoglycans from healthy and cyclosporin- and nifedipine-induced overgrown gingival tissues were analyzed by agarose gel electrophoresis and their molecular-size distribution was evaluated by both gel filtration chromatography and polyacrylamide gel electrophoresis. Our results on the gingival glycosaminoglycan composition showed presence of chondroitin sulfate, dermatan sulfate, heparan sulfate and hyaluronic acid in all types of gingival tissues examined. In addition, hyaluronic acid was predominantly of a large size eluting near to the void volume of a Superose-6 column, while the sulfated glycosaminoglycans were mainly composed of low molecular size glycosaminoglycans. Our results show no differences in the molecular-size distribution of hyaluronic acid and sulfated glycosaminoglycans among healthy and drug-induced overgrown gingival tissues.

The effect of hyaluronan on bone and soft tissue and immune response in wound healing

BACKGROUND

The aims of this study were to investigate the anti-inflammatory effect and the effect on bone regeneration of hyaluronan in surgical and non-surgical groups.

METHODS

In each of 15 individuals, 2 teeth with defects of similar character and magnitude in the upper or lower jaw were chosen. There were at least 2 teeth between the test and the control sites. In the surgical group, a bioabsorbable membrane was used for both test and control sites, and hyaluronan was placed in the intrabony pocket of the test site. In the non-surgical group, the periodontal pockets were scaled and hyaluronan was administered 3 times with an interval of 1 week in the test pockets. Alveolar bone height and bone healing patterns were analyzed using digital intraoral radiographs. Measurements of bone height were performed in the original digital black-and-white radiographs to obtain quantitative data on bone gain or loss. Bone healing patterns were studied with color-coded radiographs, using specially designed software in a personal computer with subsequent combinations of radiographs. Gingival crevicular fluid immunoglobulin (Ig)G, C3, and prostaglandin E2 (PGE2) responses; periodontal probing depth; bleeding on probing; and the presence of plaque were studied to evaluate the anti-inflammatory effect. Data were obtained at baseline before treatment, and at 2 weeks, and 1, 3, 6, and 12 months after treatment.

RESULTS

For the surgical treatments, bone height was increased in the test group treated with hyaluronan (mean value 2.2%, corresponding to an average increase of approximately 0.5 mm) and reduced in the control group (mean value -1.8%, corresponding to an average decrease of approximately - 0.4 mm) (P<0.05) after 12 months. For the non-surgical treatments, bone height was reduced by a mean value of -1.1% (corresponding to an average decrease of approximately -0.25 mm) in the test group treated with hyaluronan and -3.3% (corresponding to an average decrease of approximately -0.75 mm) in the control group after 12 months (N.S.). According to the digital color-coded radiographs, the test sites in the surgical and non-surgical groups showed apposition of bone minerals. Immune responses showed no differences during the 12 months studied for the surgical and non-surgical sites. Mean periodontal probing depths were reduced between 2.5 mm and 4.1 mm in the surgical and non-surgical groups.

CONCLUSIONS

The observed difference in bone height between test and control sites in the surgical group after 12 months was less than 1 mm, which was only detectable on radiographs. No statistical difference was found on radiographs in the non-surgical group, where a decrease in bone height was found for both groups after scaling. Probing depth reduction after the surgical treatment, as well as after scaling and root planing, was as expected. Hyaluronan in contact with bone and soft tissues had no influence on the immune system in this study. Further studies are needed to determine the extent to which hyaluronan can lead to clinically significant healing of periodontal lesions.

Use of hyaluronic acid binding protein for detection of hyaluronan in ligature-induced periodontitis tissue

This study was designed to demonstrate, by use of biotin-labeled hyaluronic acid binding protein (HABP) and an avidin-enzyme system, the localization of hyaluronan (HA) in periodontal tissue of beagle dogs during experimentally induced periodontitis. Experimental periodontitis was induced in the dogs by ligation of the gingival sulcus. Experimental tissue was collected at 0, 3, 7 and 21 days after ligation. HA was revealed by strong staining in the intercellular space around epithelial cells and periodontal ligament, and by light staining in the gingival connective tissue. According to the progression of periodontal tissue breakdown, HA was detected in a small number of leukocytes and monocytes, on the surface of osteoclasts, the surface of alveolar bone, thickened endothelium and in epithelial cells related to rete peg formation. Streptomyces hyaluronidase-treated specimens gave negative staining. This study suggests that HA may be associated with the inflammatory reaction in experimental periodontitis tissue.

Immunolocalization of glycosaminoglycans in ageing, healthy and periodontally diseased human cementum

The distribution of glycosaminoglycans in the extracellular matrix of human cementum was investigated in periodontally involved and periodontal disease-free teeth separated into eight different age groups (from 12 to 90 years), to investigate possible changes in the distribution of glycosaminoglycan species associated with ageing and periodontal disease. A standard indirect immunoperoxidase technique was used, with a panel of monoclonal antibodies, 2B6, 3B3, 5D4, and 7D4, that recognize epitopes in chondroitin-4-sulphate/dermatan sulphate (C-4S/DS), chondroitin-6-sulphate (C-6S), keratan sulphate (KS) and a novel sulphated chondroitin sulphate (CS) epitope, respectively. Intense positive staining for C4-S/DS was observed at the margins and lumina of almost all the lacunae and canaliculi in cellular cementum in all sections. Immunoreactivity to C6-S, KS and novel CS epitopes was limited to a proportion of lacunae and canaliculi in all sections, although C6-S and the novel CS epitopes were more widely distributed than KS. In acellular cementum, there was no demonstrable staining for any of the glycosaminoglycans except where periodontal ligament (Sharpey's) fibres insert; periodontal ligament fibres inserting in cellular cementum also demonstrated positive immunoreactivity. In addition, the cementoblasts on the outer root surface, as well as the pericellular areas around a proportion of these cells, demonstrated positive immunoreactivity. These results indicate that glycosaminoglycan species present in human cementum include C4-S, DS, C6-S, and novel sulphated CS epitopes. KS is also present in cementum but is limited to a more restricted proportion of lacunae and canaliculi. Regional differences in the distribution of glycosaminoglycans exist between the two cementum types, but no qualitative differences in that distribution were observed between the various age groups or between periodontally involved and periodontal disease-free teeth. The immunoreactivity observed in a proportion of lacunae after staining for C6-S, KS, and novel sulphated CS epitopes could suggest the existence of different cementocyte subpopulations.

Molecular size distribution analysis of human gingival proteoglycans and glycosaminoglycans in specific periodontal diseases

In order to determine the molecular-size distribution of gingival proteoglycans (PGs) and glycosaminoglycans (GAGs) both in periodontal health and disease states, gingival tissues were obtained from patients with early onset periodontitis (EOP) and adult periodontitis (AP) and also from periodontally healthy subjects. Gel filtration chromatography of gingival PGs revealed different profiles for periodontally diseased and healthy gingiva. Healthy gingiva was mainly composed of high-molecular size proteins and PGs, while diseased gingival tissue presented a decrease in high-molecular size PG forms and a shift towards low-molecular size proteins and PGs. This indicates the degradation of PG macromolecules during periodontal disease activity. Furthermore, this shift towards low-molecular size forms was more intense in EOP patients when compared to AP patients. Gel filtration of gingival GAGs also demonstrated depolymerization of GAGs, with low-molecular size GAGs being more intense in periodontally diseased gingiva, while healthy gingival GAGs profile was mainly composed of high-molecular size GAGs. Similar to the profile of gingival PGs, low-molecular size gingival GAGs were more prominent in gingival tissue from patients with EOP. These findings suggest that both PGs and GAGs, essential components of the extracellular matrix (ECM), are depolymerized during periodontal disease activity, which is more prominent in EOP. Since the basic feature of periodontal disease is matrix degradation, ECM components, more specifically PGs and GAGs, are likely to provide valuable information for a better understanding of periodontal disease activity.

Expression of heparan sulphate and small dermatan/chondroitin sulphate proteoglycans in chronically inflamed human periodontium

Proteoglycans (PGs) function in regulating aspects of cell behavior, such as proliferation, adhesion, and migration. In this report, we investigated the localization of three heparan sulphate PGs (basement membrane [BM] heparan sulphate PG, CD44, and syndecan-1) and two small dermatan/chondroitin sulphate PGs (decorin and biglycan) in chronically inflamed human periodontium. Frozen sections were analyzed by immunofluorescence microscopy. In inflamed tissue, BM heparan sulphate PG showed reduced immunostaining in subepithelial and subendothelial basement membrane. Loss of CD44 and syndecan-1 was common in epithelial cells of inflamed periodontal tissue. Suprabasal keratinocytes of epithelium expressed involucrin, a cornified envelope protein and marker for epithelial differentiation, while the expression of syndecan-1 was weak or absent. In contrast, expression of the mesenchymal variant of CD44 and syndecan-1 was strong in infiltrating lymphocytes. Small dermatan/chondroitin sulphate PGs, decorin and biglycan, were also present in markedly reduced amounts in the periodontal connective tissue in chronic inflammation. In addition, decorin localized in the connective tissue along short rod-like structures. The results suggest that proteoglycan-dependent intercellular adhesion of keratinocytes is decreased and that adhesion of lymphocytes to matrix molecules via cell surface PGs increased in chronic inflammation. Disappearance of adhesion-modulating small dermatan/chondroitin sulphate PGs may further regulate cell migration in inflamed periodontium.

Comparative effects of cyclosporin on glycosaminoglycan synthesis by gingival fibroblasts

Histological studies show that drug-induced gingival overgrowth results from an accumulation of the connective tissue component. Despite comprising a major part of gingival connective tissue, a role for glycosaminoglycans (GAGs) in the pathogenesis of gingival overgrowth has received scant attention. By analyzing the metabolism of 3H-glucosamine, we have compared GAG and hyaluronan synthesis by fibroblasts derived from normal and overgrown gingival tissue, and the effects of cyclosporin on GAG output. GAG production was cell density-dependent, fibroblasts cultured at low density synthesizing significantly increased quantities in comparison to confluent cultures. The effects of cyclosporin on GAG synthesis was also found to be both cell density- and cell strain-dependent. However, cyclosporin-stimulated GAG synthesis by 2/3 overgrown cell strains and 1/3 normal strains. These results suggest that a direct promotion of GAG synthesis by gingival fibroblasts in response to cyclosporin may play a role in the pathogenesis of gingival overgrowth.

Detection and possible biological role of chondroitinase and heparitinase enzymes produced by Porphyromonas gingivalis W50

Gingival crevicular fluid levels of the glycosaminoglycan (GAG) chondroitin-4-sulphate (C-4-S) have received increased attention as potential indicators of periodontal tissue turnover. However, little is known about the relationship between crevicular fluid connective tissue metabolites and microbial factors. In this study Porphyromonas gingivalis, a periodontopathogen, was investigated for its ability to degrade the GAGs C-4-S, dermatan sulphate (DS) and heparan sulphate (HS) in vitro. The effect of P. gingivalis extracts on the proteoglycans (PG) derived from human gingiva were also investigated. The presence of chondroitinase and heparitinase eliminase enzymes were identified from the vesicle fraction of P. gingivalis W50. These enzymes were extracted from the vesicle fraction by a differential centrifugation technique and partially purified by non-denaturing gel filtration chromatography which revealed heparitinase enzyme peaks at 200 and 150 kDa and chondroitinase at 70 kDa. Gingival proteoglycans for use as substrates were purified using 4 M guanidinium chloride extraction and anion exchange chromatography; these proteoglycans contained 48% DS, 27% C-4-S and 13% HS P. gingivalis chondroitinase and heparitinase enzymes were capable of the degradation of C-4-S and HS but not DS GAGs. The presence of chondroitinase enzymes produced by P. gingivalis may influence levels of connective tissue metabolites in crevicular fluid. Furthermore these enzymes, particularly the heparitinase, may be involved in the initial permeation of the gingival epithelium, permitting the ingress of further microbial virulence factors.

The synthesis of 5-alpha-dihydrotestosterone from androgens by human gingival tissues and fibroblasts in culture in response to TGF-beta and PDGF

The effects of TGF-beta and PDGF on the metabolic conversion of 14C-testosterone by human gingival tissue (HGT) from 5 subjects was investigated. The metabolic conversions in response to TGF-beta and PDGF were also studied in 4-6 cell-lines of cultured gingival fibroblasts, using 14C-testosterone and 14C-4-androstenedione as substrates. Duplicate incubations of HGT were performed in Eagle's MEM + 10% FCS and optimal stimulatory concentrations of TGF-beta/PDGF for 24 h. Similar incubations were performed in duplicate with cell-lines of cultured gingival fibroblasts, TGF-beta/PDGF, 14C-testosterone/14C-4-androstenedione in Eagle's MEM + 10% FCS. The radioactive metabolites were extracted, separated and quantified. With HGT, TGF-beta and PDGF caused 2.5/2-fold increases in DHT synthesis (p < 0.1; Wilcoxon signed rank test) and 3.4/2-fold increases in 4-androstenedione formation (p < 0.1) from 14C-testosterone. PDGF increased DHT and testosterone synthesis from 14C-4-androstenedione by 3-fold in gingivae (p < 0.1). With cell-lines, average values of duplicate incubations showed 2.8/2-fold increases in DHT synthesis from 14C-testosterone in response to TGF-beta/PDGF (p < 0.1; p < 0.2) and 2.4/2-fold increases in 4-androstenedione synthesis (p < 0.1; p < 0.2). With 14C-4-androstenedione as substrate, TGF-beta/PDGF caused 1.6/1.9-fold increases in DHT synthesis compared with controls (p < 0.05; p < 0.1) and 1.7/1.5-fold increases in testosterone formation from this substrate (p < 0.05; p < 0.1). Due to the strong implications of TGF-beta/PDGF and anabolic androgens on matrix repair, significant increases in DHT synthesis from 2 androgenic substrates in response to TGF-beta and PDGF are of particular relevance to inflammatory repair processes.

The effect of interleukin-1 (IL-1) on androgen metabolism in human gingival tissue (HGT) and periodontal ligament (PDL)

Due to the potent anabolic effects of the androgenic metabolite 5 alpha- dihydrotestosterone (DHT) on matrix synthesis by connective tissue and bone, it was pertinent to investigate the effects of interleukin-1 (IL-1) on androgen metabolism by chronically inflamed human gingival tissue (HGT) and periodontal ligament (PDL). Duplicate incubations of HGT and PDL derived from 6 subjects (age- and sex-matched) were performed in Eagle's MEM+FCS with 14C-testosterone to study baseline conversion to DHT and 4-androstenedione. Similarly further incubations were performed for 24 h in a 5% CO2 in air incubator, with HGT and PDL from 4 comparable patients to study the effect of IL-1 on this conversion. The medium was extracted radioactive metabolites separated by thin-layer chromatography and quantified. When baseline metabolism of HGT was compared with that of PDL, both tissues metabolised 14C-testosterone to DHT and 4-androstenedione. There was a 2.4-fold increase in DHT synthesis by PDL over that of HGT (n = 6; p < 0.005) and a 2.5-fold increase in 4-androstenedione formation by PDL compared with HGT (n = 6; p < 0.01). In response to IL-1, HGT demonstrated a 2-fold increase in DHT synthesis (n = 4; p < 0.005) and a 3.5-fold increase in 4-androstenedione formation (p < 0.01) over control gingival tissue; PDL showed a 9-fold increase in DHT synthesis in response to IL-1 (n = 4; p < 0.005) and a 6-fold increase in 4-androstenedione formation (p < 0.005) over control ligament tissue. The increased androgen metabolic capacity of PDL over HGT, both at baseline and in response to IL-1 is in keeping with protein studies and may be relevant to repair processes during inflammatory periodontal disease.

Localization of glycosaminoglycans in periodontal ligament during physiological and experimental tooth movement

Localization of chondroitin sulphates in periodontal ligaments (PDL) of rat molar roots during physiological and experimental tooth movement were analysed immunohistochemically with the use of monoclonal antibodies, 3B3 and 2B6, specific to chondroitin 6-sulphate (CH-6S) and chondroitin 4-sulphate/dermatan sulfate (CH-4S/DS), respectively. The maxillary first molars of experimental animals were forced to move laterally with a 10 g weight by U-shaped wires for 3 and 7 d. In control animals, 3B3 epitope was seen in the PDL near to the bone surface facing the distal half of roots, which corresponded to the compressive side during physiological tooth movement. Immunoreactivity for 2B6 was weak or negative in the PDL. Both epitopes were present at osteoid, precementum, lacunae and canaliculli of osteocytes and cementocytes. In 3-d-treated animals, the early stage of hyalinization characterized with visible cells and fibres was observed in the PDL at the buccal side of the mesial root, which showed intense immunoreactivity for 3B3. Further 3B3 positive area seen in control animals changed its position from the distal to the buccal side of the PDL. Immunoreactivity for 2B6 did not change in the PDL of 3-d-treated animals. In 7-d-treated animals, the typical hyalinization characterized with no visible cells and fibres was seen in the PDL at the buccal sides of both mesial and disto-buccal roots, where both epitopes were present at the peripheral part of the tissue. Observation of serial sections suggested that the 3B3-positive area was present at the peripheral part of the 2B6-positive area. The present results suggest that the expression of CH-6S is related to the compressive force in non-hyalinized and hyalinized PDL, whereas that of CH-4S/DS is not influenced by the mechanical stress.

Turnover in periodontal connective tissues: dynamic homeostasis of cells, collagen and ground substances

The connective tissues of the periodontium are composed of two soft tissues and two hard tissues--each of which has unique features. This review considers the constituents of normal, healthy periodontal connective tissues together with an appraisal of the changes in the connective tissue matrices of the periodontium which occur during the development of periodontitis. Recent developments in this field have paved the way for new and exciting vistas in periodontal diagnosis and regeneration which, ultimately, are two important goals in periodontal therapy.

The influence of insulin-like growth factor (IGF) on C19 steroid conversions by human gingiva and in cultured gingival fibroblasts

The metabolic conversion of 14C-testosterone by human gingival tissue in response to IGF was studied. Androgen metabolic studies were also performed in 5 to 7 cell-lines of cultured gingival fibroblasts, using 14C-testosterone and 14C-4-androstenedione as initial substrates. Duplicate incubations of gingival tissue were performed after establishing the wet weight, in Eagle's MEM + 10% FCS and optimal stimulatory concentrations of IGF for 24 hours. Similar incubations were performed in duplicate with cell-lines of gingival fibroblasts, control/IGF, and 14C-testosterone/14C-4-androstenedione. At the end of the incubation period, the radioactive metabolites were extracted, evaporated, subjected to thin layer chromatography for their separation, and quantified by scanning in a Berthold's linear analyzer. With the gingival tissue samples, IGF caused a 4-fold increase in 5 alpha-dihydrotestosterone (DHT) synthesis (n = 5; P < 0.1, Wilcoxon signed rank test for paired observations) and a 3.5-fold increase in 4-androstenedione formation (n = 5; P < 0.1) from 14C-testosterone. When similar incubations were performed with cell-lines of fibroblasts and 14C-testosterone, average values of duplicate incubations showed a 2.5-fold increase in DHT synthesis in response to IGF (n = 7; P < 0.002) and a 2.3-fold increase in 4-androstenedione formation (n = 7; P < 0.002). With 14C-4-androstenedione as substrate, IGF stimulated a 2.7-fold increase in DHT synthesis (n = 5; P < 0.1) compared with controls and a 1.8-fold increase in testosterone formation (n = 5; P < 0.1). Since both DHT and IGF are implicated in protein turnover by fibroblasts, significant stimulation of DHT synthesis by IGF in gingiva and cultured fibroblasts is suggestive of a possible mechanism for mediating inflammatory repair via the androgen metabolic pathway.

The response of human gingival fibroblasts to interleukin-1 in their metabolic conversion of two androgenic substrates

The effects of interleukin-1 (IL-1) on the metabolism of two androgenic substrates, testosterone and 4-androstenedione, that can be converted to the potent anabolic metabolite 5 alpha-dihydrotestosterone (DHT) were studied. Duplicate incubations of confluent gingival fibroblasts were made in Eagle's minimum essential medium + 10% fetal calf serum, with [14C]-testosterone/[14C]-androstenedione as initial substrates and optimal stimulatory concentrations of IL-1. [14C]-testosterone was converted mainly to DHT and 4-androstenedione. There was a 1.8-fold increase in DHT synthesis (n = 7; p < 0.02) and a 1.9-fold increase in 4-androstenedione in response to IL-1 (n = 7; p < 0.02) (Wilcoxon signed-rank test for non-parametric, paired observations). [14C]-4-androstenedione was mainly converted to DHT and testosterone. There was a 1.7-fold increase in DHT synthesis in response to IL-1 (n = 8; p < 0.01), and a 1.5-fold increase in testosterone formation from [14C]-4-androstenedione in the presence of IL-1, in six of the cell lines (n = 6; p < 0.05). Both testosterone and 4-androstenedione were effective substrates in forming the potent metabolite DHT in significant amounts in response to IL-1. This is significant in view of the well-documented effects of androgens on connective tissue and bone matrix, and may have implications for the healing potential of lesions in inflammatory periodontal disease.

Gingival crevicular fluid glycosaminoglycan levels in patients with chronic adult periodontitis

This study investigated levels of hyaluronan and chondroitin-4-sulphate in the crevicular fluid of patients with chronic adult periodontitis at diseased and healthy sites before and after treatment. The relationship between clinical diagnostic parameters and levels of glycosaminoglycans in gingival crevicular fluid were also analysed. Within each patient, 4 sites either mesial or distal and on single rooted teeth were classified as diseased or healthy using a modified gingival index, pocket depth and attachment loss. Crevicular fluid was collected from each site using glass micropipettes and analyzed for glycosaminoglycan content by cellulose acetate electrophoresis. Significantly higher levels of chondroitin-4-sulphate were detected at diseased sites prior to treatment correlating with increased pocket depth or attachment levels. Following a period of treatment consisting of oral hygiene instruction and root planing, the patients were reassessed for their response to treatment by measuring the modified gingival index, pocket depth, attachment loss and levels of glycosaminoglycans. Analysis of glycosaminoglycan levels at diseased sites that demonstrated a poor response to treatment also demonstrated significantly higher levels of chondroitin-4-sulphate than those sites that responded well to treatment. Hyaluronan levels were less significantly associated with clinically succesful treatment. This study confirmed the use of the sulphated glycosaminoglycan chondroitin-4-sulphate as a potential diagnostic aid of periodontal tissue destruction; however, further longitudinal studies are required to assess their performance.

Glycosaminoglycan synthesis in the rat articular disk in response to mechanical stress

The mechanism by which compressive mechanical stress affects glycosaminoglycan synthesis in the articular disk was investigated with a modified organ culture technique. Forty-eight male Sprague-Dawley rats were divided into three experimental groups and one control group of 12 animals each, aged 7 and 9 weeks. The experimental groups followed different regimens of stress applied for 25%, 75%, or 100% of the time during the total test period of 24 hours. Articular disks were stressed with flexible bottomed dishes (Flex I dishes, Flexcell Corp., McKeesport, Pa.) using the Flexercell Strain Unit (Flexcell Corp., McKeesport, Pa.) and incubated with [3H]-glucosamine for 24 hours. Samples were then collected, digested with Pronase-E, and after precipitation with cetylpyridinium chloride (CPC) and ethanol, the different glycosaminoglycans (GAGs) were separated by using cellulose acetate electrophoresis. The significant GAG types with stress were chondroitin6sulfate (C6S), hyaluronic acid (HA), and dermatan sulfate (DS). There was no significant relationship in the experimental groups between age and regimen of stress applied in either age. Higher stress regimens showed significantly higher proportions of C6S when compared with the controls, whereas HA appeared to decrease slightly and DS was not affected. Since C6S is the major component of hyaline cartilage, the results of this study suggest that compressive forces in the articular disk may stimulate the development of more cartilagenous-like properties with respect to GAG content.

Ultrastructural localization of glycosaminoglycans in human gingival connective tissue using cupromeronic blue

Human gingiva was stained with cupromeronic blue according to Scott's critical electrolyte concentration technique in order to localize glycosaminoglycans (GAG) in the electron microscope. Identification was performed by digestion with chondroitinase AC, ABC and heparinase. The GAG were localized in three compartments of the connective tissue: the supra-alveolar fiber apparatus, the loose connective tissue and the basement membranes. In the supra-alveolar fiber apparatus, consisting mainly of densely packed parallel collagen fibrils, dermatan sulfate GAG are regularly attached to the d-band of the collagen fibrils. The precipitates (6-7 nm in diameter) aggregate to thicker precipitates (up to 16 nm), thus possibly providing stability to the fiber system. In the loose connective tissue with sparse collagen fibrils dermatan and chondroitin sulfate GAG form very large precipitates (up to 30 nm in diameter and 400 nm length) which interconnect the few collagen fibrils. The basement membranes of the epithelium and capillary endothelium contain heparan sulfate GAG as fine precipitates (4-6 nm in diameter) which form a meshwork. These findings are consistent with the Scott model (1) for the interactions among glycans and glycans and collagen fibrils in connective tissues.

Bacterial steroidogenesis by periodontal pathogens and the effect of bacterial enzymes on steroid conversions by human gingival fibroblasts in culture

Studies were performed to investigate the effect of microbial culture supernatants of periodontal pathogens on the metabolism of radiolabelled testosterone in the presence or absence of human gingival fibroblasts. Subgingival plaque samples were obtained on paper points from 3 sites with probing depth values of 6-8 mm. Samples were incubated with 14C-testosterone for 24 h in brain heart infusion (BHI) broth. Similar incubations were also carried out with strains of A. actinomycetemcomitans, P. Intermedius and P. gingivalis to study the metabolism of radiolabelled testosterone by these periodontal pathogens. At the end of a 24 h incubation period with fibroblasts and supernatants or sonicates, the radioactive metabolites were extracted with ethyl acetate, evaporated and subjected to thin layer chromatography. The separated metabolites were quantified by scanning the radioactive plates using a Berthold linear analyser. When three sub-gingival plaque samples were incubated with radiolabelled testosterone there were 50-fold, 10-12-fold and 15-17-fold increases in 5 alpha-dihydrotestosterone (DHT) synthesis over 4-androstenedione production in these mixed microbial cultures. The two strains of P. intermedius produced 3- and 20-fold increases in 4-androstenedione production and DHT synthesis respectively. Both strains of A. actinomycetemcomitans and P. gingivalis showed 3-4-fold and 12-28-fold increases respectively in 4-androstenedione synthesis over that of DHT. Culture supernatants of P. intermedius and P. gingivalis caused 3-fold and 2-fold increases in DHT synthesis by fibroblasts over controls. There was little change in the case of the third pathogen. Since DHT has implications on matrix synthesis by fibroblasts in the environment of plaque associated inflammatory periodontal disease, bacterial metabolism and the effect of bacterial supernatants on human gingival fibroblasts can influence the degree of inflammatory repair.