Effects of bisphosphonate on matrix metalloproteinase enzymes in human periodontal ligament cells

Prenyltransferase gene expression reveals an essential role of prenylation for the inflammatory response in human gingival fibroblasts

BACKGROUND

Prenyltrasferases (PTases) are a class of enzymes known to be responsible for promoting posttranslational modification at the carboxyl terminus of proteins containing a so-called CaaX-motif. The process is responsible for proper membrane localization and the appropriate function of several intracellular signaling proteins. Current research demonstrating the pathomechanistic importance of prenylation in inflammatory illnesses emphasizes the requirement to ascertain the differential expression of PT genes under inflammatory settings, particularly in periodontal disease.

METHODS

Telomerase-immortalized human gingival fibroblasts (HGF-hTert) were cultured and treated with either inhibitors of prenylation (PTI) lonafarnib, tipifarnib, zoledronic acid, or atorvastatin at concentrations of 10 μM in combination with or without 10 μg Porphyromonas gingivalis lipopolysaccharide (LPS) for 24 h. Prenyltransferase genes FNTB, FNTA, PGGT1B, RABGGTA, RABGGTB, and PTAR1 as well as inflammatory marker genes MMP1 and IL1B were detected using quantitative real-time polymerase chain reaction (RT-qPCR). Immunoblot and protein immunoassay were used to confirm the results on the protein level.

RESULTS

RT-qPCR experiments revealed significant upregulation of IL1B, MMP1, FNTA, and PGGT1B upon LPS treatment. PTase inhibitors caused significant downregulation of the inflammatory cytokine expression. Interestingly, FNTB expression was significantly upregulated in response to any PTase inhibitor in combination with LPS, but not upon LPS treatment only, indicating a vital role of protein farnesyltransferase in the proinflammatory signaling cascade.

CONCLUSIONS

In this study, distinct PTase gene expression patterns in pro-inflammatory signaling were discovered. Moreover, PTase inhibiting drugs ameliorated inflammatory mediator expression by a significant margin, indicating that prenylation is a major pre-requisite for innate immunity in periodontal cells.

Matrix Metalloproteinases in Dental and Periodontal Tissues and Their Current Inhibitors: Developmental, Degradational and Pathological Aspects

Objectives: This review article aims to describe some of the roles of Matrix metalloproteinases (MMPs) in enamel, dentine, dental caries, hybrid layer degradation, pulp and periodontal tissues, throwing light on their current inhibitors. The article addresses the potential of MMPs to serve as biomarkers with diagnostic and therapeutic value. Design: The sections of this review discuss MMPs’ involvement in developmental, remodeling, degradational and turnover aspects of dental and periodontal tissues as well as their signals in the pathogenesis, progress of different lesions and wound healing of these tissues. The literature was searched for original research articles, review articles and theses. The literature search was conducted in PubMed and MEDLINE for articles published in the last 20 years. Results: 119 published papers, two textbooks and two doctoral theses were selected for preparing the current review. Conclusions: MMPs are significant proteases, of evident contribution in dental and periapical tissue development, health and disease processes, with promising potential for use as diagnostic and prognostic disease biomarkers. Continuing understanding of their role in pathogenesis and progress of different dental, periapical and periodontal lesions, as well as in dentine-pulp wound healing could be a keystone to future diagnostic and therapeutic regimens.

Quantitative assessment of two methods of tiludronate administration for the treatment of lameness caused by navicular syndrome in horses

OBJECTIVE

To determine effects of 2 tiludronate administration protocols on measures of lameness in horses with navicular syndrome (NS).

ANIMALS

12 horses with bilateral forelimb NS.

PROCEDURES

Horses were randomly assigned to receive tiludronate (1 mg/kg), diluted in 5 L of isotonic electrolyte solution and delivered through a jugular vein catheter (systemic treatment group; n = 6), or tiludronate (0.1 mg/kg), diluted with saline (0.9% NaCl) solution to a total volume of 35 mL and delivered into the lateral digital vein of each forelimb with an IV regional limb perfusion (IVRLP) technique (IVRLP group; 6). Mean peak vertical ground reaction force (pVGRF) measured with a stationary force plate and subjective lameness scores (SLSs) were recorded before (day -1) and at predetermined time points after tiludronate administration on day 0. Mean pVGRFs (standardized as percentage body weight of force) and mean SLSs for the most lame forelimb and for both forelimbs of horses in each group were compared with day -1 values to determine treatment effect.

RESULTS

Mean pVGRF for both forelimbs and for the most lame forelimbs of systemically treated horses were significantly increased on days 120 and 200, compared with day -1 results. No significant difference in mean pVGRF was observed for IVRLP-treated horses. The SLSs were not improved at any time point following systemic treatment and were improved only on day 120 following IVRLP.

CONCLUSIONS AND CLINICAL RELEVANCE

Tiludronate (1 mg/kg, IV) as a single systemic treatment appeared to be beneficial for horses with NS, but no horses were judged as sound during the study period. Additional research on IVRLP with tiludronate is needed before this method can be recommended.

Clinical and radiographic evaluation of effect of risedronate 5 mg as an adjunct to treatment of chronic periodontitis in postmenopausal women (12-month study)

Bisphosphonates are beneficial to women, after menopause, in treatment of gum diseases. In this study, significant improvement in the disease condition was found and that no further progress was noted, and no side effects were reported. Bisphosphonates can be safely and successfully be used to support oral health procedures.

INTRODUCTION

The purpose of this study was to evaluate host modulating effect of bisphosphonate adjunct with the treatment of chronic periodontitis in osteopenic and osteoporotic postmenopausal women.

METHODS

Twenty-two osteopenic and osteoporotic postmenopausal women with moderate to severe chronic periodontitis were selected for the study. On intraoral examination, periodontal parameters like probing depth (PD), clinical attachment level (CAL), Plaque Index (PI) and Gingival Index (GI) were recorded. Scaling and root planing were done. Intraoral periapical X-rays were taken, and alveolar bone density (ABD) was measured with cone beam computed tomography (CBCT), and then, medications (risedronate 5 mg once daily (OD), calcium citrate 250 mg OD, vitamin D 400 IU OD) were given. Patients were recalled for follow-up at 3, 6 and 12 months. Intraoral periapical (IOPA) X-rays were taken at 6 and 12 months and ABD was measured at baseline and 12 months.

RESULTS

There was a significant improvement in all the parameters. There was an increase of 0.02 ± 0.001 cm on CT scan and 0.38 ± 0.005 mm on IOPA in bone height over 12 months from baseline. Bone density increased by 118.56 ± 3.251 Hounsfield units (HU). There was no progress in the disease, and further bone loss was not noticed. This is in correlation with clinical parameters which showed highly significant gain in CAL (3.57 ± 0.234 mm) and reduction in PD (2.20 ± 0.229 mm)

CONCLUSIONS

Bisphosphonate therapy as an adjunct to scaling and root planing may have significant beneficial clinical effects on the periodontium of postmenopausal women with moderate to severe chronic periodontitis.

Effects of zoledronate on irradiated bone in vivo: analysis of the collagen types I, V and their cross-links lysylpyridinoline, hydroxylysylpyridinoline and hydroxyproline

Radiotherapy can lead to a reduction of bone density with an increased risk of pathological fractures. Bisphosphonates may represent a preventive treatment option by increasing the density of anorganic bone mineral. Yet it is unknown how bisphosphonates act on irradiated collagen cross-links, which play an essential role for the mechanical stability of bone. The aim of this study was to evaluate the effects of zoledronate on bone collagens and their cross-links after irradiation. The right femur of 37 rats was irradiated with a single dose of 9.5 Gy at a high dose rate using an afterloading machine. Half of the rats (n=18) received additionally a single dose zoledronate (0.1 mg/kg body weight). Fourteen and 100 days after irradiation the femora were collected for histologic evaluation and determination of the collagen cross-links lysylpyridinoline, hydroxylysylpyridinoline, and hydroxyproline. The collagen types were characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Fourteen days after treatment the lysylpyridinoline levels of all treatment groups were significantly lower compared to the untreated control. After 100 days, in the combined radiotherapy+zoledronate group significantly lower lysylpyridinoline values were determined (p=0.009). Radiotherapy and/or zoledronate did not change significantly the level of hydroxylysylpyridinoline. The concentration of hydroxyproline was 14 days after irradiation significantly higher in the combined treatment group compared to the control. No significant differences were observed 100 days after treatment. Zoledronate does not have the ability to restore the physiological bone collagen cross-link levels after radiotherapy. However, this would be necessary for regaining the physiological mechanical stability of bone after irradiation and therefore to prevent effectively radiation-induced fractures.

Effect of Porphyromonas gingivalis and Lactobacillus acidophilus on secretion of IL1B, IL6, and IL8 by gingival epithelial cells

Porphyromonas gingivalis alters cytokine expression in gingival epithelial cells, stimulating inflammatory responses that may lead to periodontal disease. This study explored the effect of Lactobacillus acidophilus on the specific expressions of the interleukins (ILs) IL1B, IL6, and IL8 induced by the pathogen. Human gingival epithelial cells were co-cultured with P. gingivalis, L. acidophilus, or L. acidophilus + P. gingivalis; the control group consisted of the cells alone. Protein and gene expression levels of the ILs were detected using ELISA and qRT-PCR, respectively. The supernatant from the P. gingivalis group held significantly higher protein and mRNA levels of IL1B, IL6, and IL8, compared to the control group. In the mixed bacterial group (L. acidophilus + P. gingivalis), the levels of all three ILs decreased with increasing concentrations of L. acidophilus and were significantly different from the P. gingivalis group. This suggests that in gingival cells, L. acidophilus offsets the P. gingivalis-induced secretion of these ILs in a dose-dependent manner.

Effects of alendronate on human osteoblast-like MG63 cells and matrix metalloproteinases

OBJECTIVE

The objective of this study was to examine the effects of alendronate on the expression and activity of matrix metalloproteinases (MMPs) and the expression of the tissue inhibitors of MMPs (TIMPs) from human osteoblast-like MG63 cells.

MATERIALS AND METHODS

MG63 cells were exposed to various concentrations of alendronate. Cell proliferation and cytotoxicity were evaluated by water-soluble tetrazolium-1 and lactate dehydrogenase, respectively. MG63-mediated collagen degradation was assessed utilising Type I collagen assays. Conditioned media and membrane extracts were collected for Western blot analyses of select MMPs and TIMPs. Gelatin zymography gels were incubated with alendronate to assess its effects on MMP-2 activity.

RESULTS

Alendronate affected MG63 proliferation and cytotoxicity at concentrations equal to/or greater than 10(-5) M (all p < 0.05). There were no significant differences in the collagen degrading ability of treated cells at non-toxic levels vs. untreated cells. Alendronate had no effects on the expression of MMP-2 or MT1-MMP (membrane type-1 MMP) in the conditioned media or membrane extracts, and of MMP-1 or TIMP-2 in the conditioned media. TIMP-2 in the membrane extracts was not detectable. MMP-2 activity in the zymograms was inhibited by 10(-3) and 10(-2) M alendronate.

CONCLUSION

Alendronate at 10(-5) M or higher was toxic to the cells. Alendronate at 10(-8) to 10(-6) M did not alter the expression of MMP-1, MMP-2, MT1-MMP or TIMP-2, as well as did not alter collagen degradation. Alendronate inhibited MMP-2 activity at 10(-3) and 10(-2) M in the zymograms. In conclusion, non-toxic levels of alendronate (10(-8) to 10(-6) M) did not alter MMP expression in MG63 cells or inhibit MMP-2 activity.

Tiludronate treatment improves structural changes and symptoms of osteoarthritis in the canine anterior cruciate ligament model

Introduction

The aim of this prospective, randomized, controlled, double-blind study was to evaluate the effects of tiludronate (TLN), a bisphosphonate, on structural, biochemical and molecular changes and function in an experimental dog model of osteoarthritis (OA).

Methods

Baseline values were established the week preceding surgical transection of the right cranial/anterior cruciate ligament, with eight dogs serving as OA placebo controls and eight others receiving four TLN injections (2 mg/kg subcutaneously) at two-week intervals starting the day of surgery for eight weeks. At baseline, Week 4 and Week 8, the functional outcome was evaluated using kinetic gait analysis, telemetered locomotor actimetry and video-automated behaviour capture. Pain impairment was assessed using a composite numerical rating scale (NRS), a visual analog scale, and electrodermal activity (EDA). At necropsy (Week 8), macroscopic and histomorphological analyses of synovium, cartilage and subchondral bone of the femoral condyles and tibial plateaus were assessed. Immunohistochemistry of cartilage (matrix metalloproteinase (MMP)-1, MMP-13, and a disintegrin and metalloproteinase domain with thrombospondin motifs (ADAMTS5)) and subchondral bone (cathepsin K) was performed. Synovial fluid was analyzed for inflammatory (PGE₂ and nitrite/nitrate levels) biomarkers. Statistical analyses (mixed and generalized linear models) were performed with an α-threshold of 0.05.

Results

A better functional outcome was observed in TLN dogs than OA placebo controls. Hence, TLN dogs had lower gait disability (P = 0.04 at Week 8) and NRS score (P = 0.03, group effect), and demonstrated behaviours of painless condition with the video-capture (P < 0.04). Dogs treated with TLN demonstrated a trend toward improved actimetry and less pain according to EDA. Macroscopically, both groups had similar level of morphometric lesions, TLN-treated dogs having less joint effusion (P = 0.01), reduced synovial fluid levels of PGE₂ (P = 0.02), nitrites/nitrates (P = 0.01), lower synovitis score (P < 0.01) and a greater subchondral bone surface (P < 0.01). Immunohistochemical staining revealed lower levels in TLN-treated dogs of MMP-13 (P = 0.02), ADAMTS5 (P = 0.02) in cartilage and cathepsin K (P = 0.02) in subchondral bone.

Conclusion

Tiludronate treatment demonstrated a positive effect on gait disability and joint symptoms. This is likely related to the positive influence of the treatment at improving some OA structural changes and reducing the synthesis of catabolic and inflammatory mediators.

Is long-term bisphosphonate therapy associated with benefits to the periodontium in postmenopausal women?

OBJECTIVE

The aim of this study was to compare the periodontium of postmenopausal women with known low bone mineral density who are receiving long-term bisphosphonate therapy with those who are not.

METHODS

The periodontal status of 28 white postmenopausal women with low bone density using bisphosphonate therapy for at least 2 years was compared with that of a matching group not using such therapy. All women underwent a cone-beam CT scan of the jaw and a complete periodontal examination evaluating for plaque score, periodontal probing depth, clinical attachment loss, bleeding on probing, and alveolar bone height.

RESULTS

Bisphosphonate users had higher plaque score, lower probing depth, and lesser clinical attachment loss compared with the controls. These differences were determined to be significant by both t test and Wilcoxon's tests. Bleeding on probing was lower and the alveolar bone height was higher in the bisphosphonate group than in controls, but these differences were not statistically significant. Linear models showed no significant interactions between plaque score and bisphosphonate use, suggesting that the association of periodontal status and outcome measures was constant across all levels of plaque scores. Bisphosphonate use was a significant factor for probing depth but was not significant for the other parameters when adjusted for plaque score.

CONCLUSIONS

Long-term bisphosphonate use seems to have some beneficial effects on the periodontium of postmenopausal women with low bone density, across all levels of plaque score.

Alendronate prevents bone loss and improves tendon-to-bone repair strength in a canine model

Previously we showed a loss of bone and a concomitant decrease in mechanical properties in the first 21 days after flexor tendon insertion site injury and repair in a canine model. The goal of this short-term study was to suppress bone loss after insertion site repair using alendronate in an attempt to prevent the reduction in biomechanical properties. Flexor tendons of the second and fifth digits of the right forelimbs of canines were injured and repaired. Dogs received a daily oral dose of alendronate (2 mg/kg). One digit in each dog also received a local dose of alendronate in the bone tunnel at the time of surgery. The repair was evaluated for bone mineral density (BMD) and biomechanical properties and compared to data from a previous study in which no alendronate was used. Alendronate was effective in protecting the distal phalanx from resorption during tendon-to-bone healing (BMD was 94 and 104% of control for systemic alendronate and for systemic plus local alendronate, respectively). Alendronate treatment prevented much of the decrease in ultimate load that occurs in the first 21 days. Without treatment, ultimate load was 42% of control. With systemic alendronate treatment and systemic plus local alendronate treatment, ultimate load was 78 and 69% of control, respectively. Failure mode was significantly different when comparing alendronate treatment to repair alone. A lower incidence of suture pull through was found in alendronate treated dogs, suggesting less tendon degeneration. Ultimate load can be improved in association with preventing the bone loss that normally occurs during the early period following tendon-to-bone repair. These initial short-term data demonstrate the potential for a clinical treatment that could enhance tendon-to-bone healing.

Effects of Enamel Matrix Derivative on Bone-Related mRNA Expression in Human Periodontal Ligament Cells In Vitro

BACKGROUND

Enamel matrix derivative (EMD) has demonstrated the potential to stimulate periodontal regeneration with mineralized tissue formation. Molecular regulators of bone metabolism include osteoprotegrin (OPG), receptor activator of nuclear factor kappa B ligand (RANKL), cyclooxygenase 2 (COX2), and core binding factor alpha 1 (Cbfa1). The role of these regulatory molecules within the context of EMD stimulation of mineralized tissue formation is unknown. Therefore, the purpose of this investigation was to explore the effects of EMD on these bone-related molecules in human periodontal ligament (PDL) cells.

METHODS

Human PDL-cell cultures were treated with EMD (5 to 100 microg/ml) for 24 hours. Total RNA was isolated using phenolchloroform, and reverse transcription-polymerase chain reaction (RT-PCR) was performed using primers specific for OPG, RANKL, COX2, Cbfa1, and aldolase, with amplification in the exponential range for each molecule studied.

RESULTS

The results of this study show that there is a significant (P <0.05) increase in COX2 mRNA levels with EMD treatment, and no effects were noted on mRNA levels for Cbfa1. RANKL mRNA levels were significantly decreased (P <0.01) up to 50% with EMD treatment > or =25 microg/ml. OPG levels showed minimal effects with EMD treatment. However, the RANKL/OPG ratio showed a 40% to 55% reduction with EMD >or =25 microg/ml.

CONCLUSION

This study supports a role for EMD stimulation of mineralized tissue formation consistent with periodontal regeneration by modulating regulatory molecules critical to bone metabolism at the RNA level.

Effect of Topical Administration of Monosodium Olpadronate on Experimental Periodontitis in Rats

BACKGROUND

Periodontitis is characterized by gingival inflammation, periodontal pocket formation, and bacterial plaque that lead to alveolar bone destruction. Research studies have recently begun to evaluate the effect of antiresorptive agents using experimental models of periodontitis. Bisphosphonates are the most frequently tested antiresorptive agents; their main effect is inhibition of bone resorption. The aim of this study was to perform a histomorphometric evaluation of the preventive effect of monosodium olpadronate (OPD), an aminobisphosphonate, on experimental periodontitis (EP).

METHODS

Twenty male Wistar rats were used in this experiment. The animals were assigned to one of two groups: group I: EP; and group II: EP plus topical administration of OPD (EP + OPD). The contralateral side in both groups served as untreated controls (CI and CII), respectively. Mesio-distally oriented sections of each lower first molar were obtained for histomorphometric evaluation.

RESULTS

The treated group (EP + OPD) exhibited marked inhibition of bone loss; interradicular bone volume was significantly greater than that observed in the EP group. The height of the periodontal ligament in the interradicular alveolar bone, which served as an indirect measure of bone loss, was found to be significantly increased in the EP group as compared to the EP + OPD group. Osteoclasts in the OPD treated group were detached from the bone surface, were round in shape, and exhibited a loss of polarity and lack of ruffled borders.

CONCLUSIONS

The dose used herein was found to inhibit bone loss and to cause marked morphologic changes in osteoclasts. The drug effectively prevented bone loss caused by periodontitis.

Periodontal assessment of postmenopausal women receiving risedronate

OBJECTIVE

The purpose of this study was to compare periodontal status of postmenopausal women with mild to moderate osteoporosis who use risedronate therapy with those who do not.

DESIGN

In this cross-sectional study, a total of 60 age-matched postmenopausal women with mild to moderate osteoporosis diagnosed by a bone density scan T score below -2.5 at either spine or hip were divided into two groups. Women in the experimental group had used systemic risedronate once weekly (35 mg) for at least 3 months. Women in the control group had never used bisphosphonate therapy. The periodontal status of each subject was evaluated through a clinical periodontal examination including evaluation of periodontal probing depth, gingival recession, gingival index, plaque score, attachment loss, and alveolar bone level. The significance in differences between the two groups was assessed using two-tailed paired t tests.

RESULTS

Significant differences (P < 0.05) were found between risedronate and control groups for periodontal probing depth (2.6 vs 2.9 mm), gingival index (0.37 vs 0.71), plaque score (56.2 vs 77.0), attachment loss (2.8 vs 3.2 mm), and alveolar bone level (3.1 and 4.0), respectively. Gingival recession parameters did not differ significantly. Five of six periodontal parameters evaluated show that postmenopausal women with mild to moderate osteoporosis using risedronate therapy have healthier periodontal status than those who do not use bisphosphonates.

CONCLUSIONS

Women using risedronate therapy show significantly less plaque accumulation, less gingival inflammation, lower probing depths, less periodontal attachment loss, and greater alveolar bone levels. These observations suggest that risedronate therapy may play a beneficial role in periodontal status.

Host response modulation in the management of periodontal diseases

OBJECTIVE

To review the biological mechanisms and clinical utility of therapeutic modulation of the host response in the management of periodontal diseases.

MATERIAL AND METHODS

A search of MEDLINE-PubMed was performed up to and including December 2004. The search was limited to in vitro, experimental animal and clinical studies published in English. The selection criteria included all levels of available evidence: systematic reviews, randomised-controlled clinical trials, controlled clinical trials, prospective and retrospective cohort studies and case reports of human and experimental animal studies.

RESULTS

Six targets for non-microbial chemotherapeutic intervention were identified. Clinical trials have demonstrated the ability of non-steroidal anti-inflammatory drugs to slow periodontal disease progression. However, recently reported serious adverse effects preclude the use of cyclooxygenase-2 inhibitors as an adjunct to periodontal therapy. Adjunctive use of subantimicrobial dose doxycycline to non-surgical periodontal therapy is beneficial in the management of chronic periodontitis over 12 months. Controversial data exist on the effects of bisphosphonate administration as an adjunct to periodontal therapy. Evidence on modulation of other host mediators including lipoxins, cytokines and nitric oxide synthase is limited to animal research.

CONCLUSION

After validation in long-term clinical trials, adjunctive host modulation therapy may prove advantageous in the management of periodontal diseases.

Bisphosphonate therapy improves the outcome of conventional periodontal treatment: results of a 12-month, randomized, placebo-controlled study

BACKGROUND

Bone loss in periodontitis results from inflammatory reactions that stimulate osteoclastic bone resorption. Bisphosphonates inhibit bone resorption and increase bone mass. This study evaluated the effect of bisphosphonate therapy as an adjunct to non-surgical periodontal treatment in patients with moderate to severe chronic periodontitis.

METHODS

Patients were randomized (2:1) to one of two bisphosphonate therapies or placebo for 1 year. All patients received non-surgical periodontal treatment (scaling, root planing) and periodontal maintenance therapy every 3 months. Clinical assessments at baseline and 6 and 12 months included clinical attachment level (CAL), probing depth (PD), and bleeding on probing (BOP). Periodontal bone mass was assessed by dental radiographs at baseline and 12 months using fractal analysis and digital subtraction radiography (DSR).

RESULTS

Seventy patients were randomized, 43 to the bisphosphonate group and 27 to the placebo group. Bisphosphonate therapy significantly improved CAL, PD, and BOP relative to the placebo group during the 6- to 12-month period (CAL, P = 0.0002; PD, P = 0.0156; BOP, P = 0.0079). There was no difference in the change in periodontal bone mass between the bisphosphonate and placebo groups as measured by fractal analysis and DSR.

CONCLUSION

These data suggest that bisphosphonate treatment improves the clinical outcome of non-surgical periodontal therapy and may be an appropriate adjunctive treatment to preserve periodontal bone mass.

Effects of phase I periodontal treatment on gingival crevicular fluid levels of matrix metalloproteinase-3 and tissue inhibitor of metalloproteinase-1

OBJECTIVES

The aim of this study was to evaluate the effects of phase I periodontal treatment on gingival crevicular fluid (GCF) levels of matrix metalloproteinase (MMP)-3 and tissue inhibitors of metalloproteinase (TIMP)-1.

METHODS

Plaque index, gingival index, pocket depth and clinical attachment loss were recorded and GCF samples were collected from 20 chronic periodontitis (CP) patients and 20 periodontally healthy controls (C) before treatment. CP patients received phase I periodontal treatment and all clinical parameters were recorded and GCF samples were collected once more after treatment. Assays were performed by an enzyme-linked immunosorbent assay.

RESULTS

All of the clinical parameters improved significantly after the therapy (p<0.05). Baseline GCF levels of MMP-3 were significantly higher than C and that level was reduced significantly by treatment compared with baseline levels (p<0.05). Baseline GCF levels of TIMP-1 were lower than post-treatment levels and C (p<0.05). GCF levels of TIMP-1 increased significantly by treatment compared with baseline levels (p<0.05).

CONCLUSION

This study shows that the clinical improvements after phase I periodontal therapy are accompanied by reduction in MMP-3 and increasing in TIMP-1 GCF levels.

Effects of combined systemic administration of low-dose doxycycline and alendronate on endotoxin-induced periodontitis in rats

BACKGROUND

Doxycycline has been widely used in periodontal treatment for its antimicrobial and anti-enzymatic effects. Recently, bisphosphonates have been shown to inhibit alveolar bone resorption. The aim of the present study was to evaluate the effects of doxycycline and the bisphosphonate alendronate on the gingival tissue levels of prostaglandin E2 (PGE2), prostaglandin F2alpha (PGF2alpha), leukotriene B4 (LTB4), and platelet-activating factor (PAF) in endotoxin-induced periodontal breakdown in rats.

METHODS

Experimental periodontitis was induced by repeated injection of Escherichia coli endotoxin (LPS) and 44 adult male Sprague-Dawley rats were divided into five study groups as follows: LPS, doxycycline + LPS, alendronate + LPS, doxycycline + alendronate + LPS, and saline control. Doxycycline and alendronate were given either as a single agent or as a combination therapy during the 7-day study period. At the end of the 1-week protocol, the rats were sacrificed, the gingival tissues were dissected and extracted, and the extracts were analyzed for PGE2, PGF2alpha, LTB4, and PAF levels. The defleshed jaws were analyzed morphometrically for alveolar bone loss. Data were evaluated statistically by using parametric tests.

RESULTS

Alveolar bone loss measurements revealed significantly higher values in LPS, doxycycline + LPS, alendronate + LPS, and doxycycline + alendronate + LPS groups in comparison to the saline control group (P <0.05). Combined administration of doxycycline and alendronate exhibited the most prominent inhibition on gingival tissue levels of PGE2 and PGF2alpha (P<0.05). Doxycycline + alendronate + LPS group also significantly reduced LTB4 and PAF levels, although doxycycline provided the most reduction in the levels of these mediators (P <0.05).

CONCLUSIONS

Alendronate and/or doxycycline may provide significant inhibition of the major inflammatory mediators of periodontal tissue destruction, and combined administration of these agents may provide beneficial effects in periodontal treatment. However, this hypothesis must be further verified by clinical human trials before introducing its use in dental practice.

Periodontal host modulation with antiproteinase, anti-inflammatory, and bone-sparing agents. A systematic review

BACKGROUND

The use of modulating agents, including inhibition of matrix metalloproteinases (MMPs) with antiproteinases, blocking production of proinflammatory cytokines and prostaglandins with anti-inflammatory drugs, and inhibiting activation of osteoclasts with bone-sparing agents, has been postulated to be of therapeutic value as an adjunctive therapy to the management of chronic periodontitis.

RATIONALE

The objective of this systematic review of the literature was to assess the adjunctive efficacy of antiproteinase, anti-inflammatory, and bone-sparing host-modulating agents in the treatment of gingivitis, aggressive periodontitis, and chronic periodontitis. FOCUSED QUESTIONS: 1. In patients with periodontal diseases, what is the effect of host-modulation agents, alone or combined with conventional therapy, compared to conventional therapy alone as assessed by clinical, radiographic, adverse, and patient-centered outcomes? 2. In patients with dental implants, what is the effect of host-modulation agents on implant success assessed by clinical, radiographic, adverse, and patient-centered outcomes?

SEARCH PROTOCOL

MEDLINE, Embase, and the Cochrane Library databases were searched without language restrictions through April 1, 2002 for studies that used tetracycline (TET)-related matrix metalloproteinase (MMP) inhibitors, or non-steroidal anti-inflammatory drugs (NSAIDs) and bisphosphonate anti-osteolytic agents. The investigation also included hand searching of journals and contacting authors and industry experts.

SELECTION CRITERIA

INCLUSION CRITERIA

Only human studies (randomized controlled clinical trials, cohort studies, case-control studies, cross-sectional studies, and case series) were selected. Studies were on subjects with gingivitis, aggressive or chronic periodontitis, or dental implants. Interventions included TET-related MMP inhibitors, NSAIDs, or bisphosphonate anti-osteolytic agents.

EXCLUSION CRITERIA

Studies that used MMP tissue inhibitors as diagnostic or prognostic indicators of periodontal disease or that evaluated short-term systemic antibodies or locally delivered levels of drugs with antiproteinase activity were excluded.

DATA COLLECTION AND ANALYSIS

The primary outcomes for assessment were changes in bone or clinical attachment levels (CAL); secondary outcomes included clinical measures of plaque, gingival inflammation, probing depth (PD), and mobility. Summary data appropriate for meta-analysis were pooled using a weighted average and analyzed using a standardized difference; the results were checked with both fixed-effects and random-effects models.

MAIN RESULTS

1. A meta-analysis done on the studies reporting changes in CAL and PD following administration of sub-antimicrobial doses of doxycycline (SDD) in conjunction with scaling and root planing (SRP) in patients with periodontitis showed a statistically significant beneficial adjunctive effect. 2. There were insufficient data to provide meta-analyses on periodontal patients treated with other host-modulating agents; descriptive tables are included. 3. NSAIDS show promise in their ability to slow periodontal disease. 4. Preliminary data on bisphosphonate agents indicate there is a potential role for these agents in periodontitis management. 5. There are a very limited number of studies on host-modulating agents and dental implants and no analyses were possible. 6. Because the treatment methodologies and clinical variables differed considerably among the studies, it is difficult to summarize the information and identify a reliable total patient population.

REVIEWERS' CONCLUSIONS

1. Large multi-center trials are needed to evaluate the role of host-modulating agents in the treatment of periodontitis. 2. NSAIDS and bisphosphonate drugs may have a potential adjunctive role in periodontal therapy. 3. The adjunctive use of SDD with SRP is statistically more effective than SRP alone in reducing PD and in achieving CAL gain.

A Histopathological Investigation on the Effect of Systemic Administration of the Bisphosphonate Alendronate on Resorptive Phase Following Mucoperiosteal Flap Surgery in the Rat Mandible

BACKGROUND

The present study was designed to assess histopathologically whether the systemic administration of aminobisphosphonate (alendronate), 0.5 mg/kg body weight, is effective in preventing alveolar bone resorption following mucoperiosteal flap surgery, and whether alendronate modulates tissue factors.

METHODS

The effect of alendronate on bone resorption was evaluated in mucoperiosteal flaps used as a resorptive model. The animals were given subcutaneous injections of either saline (control group) or 0.5 mg/kg of alendronate (experimental group). The alendronate or saline was administered subcutaneously 1 week prior to surgery, immediately prior to surgery, and 1 week after surgery. The parameters determined with a semiquantitative subjective method for histopathological evaluation were as follows: inflammatory cell infiltration (ICI) of adjacent periodontal tissue, degree of fibrosis and collagen bundle formation, number and morphology of osteoclasts of the alveolar bone and interdental septum, resorption lacunae (osteoclast surfaces), and osteoblastic activity (forming surfaces).

RESULTS

There were no statistically significant differences between the saline and alendronate groups with regard to inflammatory cell infiltration, number of osteoclasts, and osteoblastic activity. Fibrosis and collagen bundle formation, osteoclast morphologies, and resorption lacunae formation were significantly different between the two groups, in favor of the alendronate group.

CONCLUSIONS

The systemic administration of 0.5 mg/kg alendronate was effective in preventing alveolar bone loss and in modulating tissue factors. These findings indicate that alendronate would be a valuable addition to the therapeutic armamentarium available for the treatment of periodontal diseases, either alone or in combination with regenerative components such as anti-inflammatory drugs, bone graft materials, and guided tissue regeneration techniques, and even with dental implants.

Combined local application of tetracycline and bisphosphonate reduces alveolar bone resorption in rats

BACKGROUND

Recent animal studies have shown that a combination of chemically-modified tetracyclines together with bisphosphonates, when delivered systemically, are synergistically effective in suppressing periodontal bone loss. In the present study, we explored the combined efficacy of local delivery of alendronate and tetracyclines in reducing alveolar bone loss.

METHODS

Eighty-six (86) male Wistar rats were used in these experiments. The flap was elevated using a special periosteal elevator, on both sides of the mandible, as described previously. A gelfoam pellet containing the drugs was applied between the alveolar bone and the mucoperiosteal flap, according to the experimental protocol. The rats were divided into 5 treatment groups: 1) alendronate; 2) doxycycline hyclate 10% (DOXY); 3) tetracycline hydrochloride 1% (TET); 4) alendronate + DOXY; and 5) alendronate + TET. In the operated control sites (C), saline was applied. The rats were sacrificed 21 days following the flap procedure. Sections of the mandibles (1.5 mm), in a buccal-lingual direction, underwent microradiography and were analyzed for bone loss.

RESULTS

DOXY alone was most effective in reducing bone loss. Alendronate was also effective in reducing bone loss as shown in previous reports. TET did not reduce bone loss significantly when used alone. In combination with alendronate TET was synergistically effective. The combined local treatment of alendronate + DOXY showed no additive effect.

CONCLUSIONS

In the present study, we found that tetracyclines can be most effective in reducing alveolar bone loss when applied locally. The combined local treatment of alendronate and tetracycline may have a synergistic effect.

Inhibition of matrix metalloproteinase-14 in osteosarcoma cells by clodronate

BACKGROUND

Bisphosphonates reduce the bone metastasis formation and angiogenesis but the exact molecular mechanisms involved are unclear. Progelatinase A (proMMP-2; 78 KDa) is activated up during the tumor spread and metastasis by a cell surface-associated matrix metalloproteinase (membrane-type matrix metalloproteinase [MT1-MMP] or MMP-14).

MATERIAL AND METHODS

We evaluated the effects of a bisphosphonate (clodronate) on MT1-MMP mRNA expression and protein production, catalytic activity and proteolytic activation of proMMP-2 by cultured human MG-63 osteosarcoma cells.

RESULTS

Clodronate, at therapeutically attainable noncytotoxic concentrations, dose-dependently inhibited phorbol myristic acetate (PMA)-induced proteolytic activation of proMMP-2 by human MG-63 osteosarcoma cells. Clodronate also downregulated the PMA-induced expression of MT1-MMP mRNA and protein production in human MG-63 osteosarcoma cells, as evidenced by Northern analysis and fluorescent immunohistochemistry. Furthermore, clodronate inhibited directly and dose-dependently MT1-MMP activity, and the MT1-MMP inhibition by clodronate was reduced in the presence of an increased (5 mM) Ca(2+) concentrations when compared to physiological (1 mM) Ca(2+) concentrations.

CONCLUSION

We conclude that (1) the extracellular/cell-associated mechanism of bisphosphonate involves inhibition of MT1-MMP catalytic activity eventually by chelation, and that (2) intracellular mechanism involves downregulation of induced MT1-MMP mRNA and protein expression. The inhibition and downregulation of MT1-MMP by clodronate can be related to their ability to reduce MG-63 osteosarcoma cell invasion and spread. These findings may, at least in part, explain at molecular level the antitumor and antibone resorption activities of clodronate observed in clinical studies.

Inhibitory effects of incadronate on the progression of rat experimental periodontitis by porphyromonas gingivalis infection

BACKGROUND

Incadronate (YM175, disodium cycloheptylaminomethylenediphosphonate monohydrate), a bisphosphonate, has been suggested to prevent the bone resorption associated with periodontitis by inhibiting osteoclast activity. The purpose of this study was to investigate the effect of incadronate in preventing periodontal destruction in rats with Porphyromonas gingivalis-induced periodontitis.

METHODS

Periodontitis was induced in 35 Wister rats by inoculating P. gingivalis into the oral cavity and feeding the rats a soft diet for 4 weeks. Incadronate or placebo was administered to the oral cavity of the rats 2 days per week for 2, 4, or 8 weeks.

RESULTS

P. gingivalis infection resulted in destruction of the periodontal ligament, reduced bone density, and caused inflammatory cell migration. Radiographic, morphometric, and histological results showed that incadronate had the ability to increase the bone mineral density (quantum level score; cortex 518.9 [placebo 612.8]; sponge 579.8 [placebo 672.0]) and to prevent periodontal ligament destruction (width 0.16 mm [placebo 0.20 mm]; area 0.36 mm2 [placebo 0.54 mm2]) after 8 weeks' administration. Furthermore, the polymorphonuclear leukocyte (PMN) infiltration in gingival tissue was significantly decreased.

CONCLUSION

These results showed that incadronate inhibits bone resorption and PMN migration in P. gingivalis-induced periodontitis.

Emerging concepts in periodontal therapy

Conventional periodontal therapy consists of mechanical scaling and root planing, and surgical treatment. This is still the mainstay of periodontal treatment. Adjunctive antimicrobial treatments, both systemic and local delivery, are becoming more sophisticated and useful in the treatment of recurrent periodontitis. Also very promising are adjunctive treatments that modulate the host response and decrease levels of destructive pro-inflammatory cytokines or matrix metalloproteinases. Smoking is a major risk factor for periodontitis and has a profound impact on the progression of periodontal bone and attachment loss. In the interest of improved periodontal health patients should be encouraged to stop smoking. Finally bacterial endotoxins that stimulate the release of pro-inflammatory cytokines can have systemic effects and may lead to pre-term, low birthweight babies, and cardiovascular diseases such as atherosclerosis, myocardial infarction and stroke. Health professionals need to be cognisant of the effect dental health can have on systemic diseases and refer for treatment when appropriate to ensure that optimum oral and systemic health is achieved for their patients.

Drugs in development: bisphosphonates and metalloproteinase inhibitors

The destruction of bone and cartilage is characteristic of the progression of musculoskeletal diseases. The present review discusses the developments made with two different classes of drugs, the bisphosphonates and matrix metalloproteinase inhibitors. Bisphosphonates have proven to be an effective and safe treatment for the prevention of bone loss, especially in osteoporotic disease, and may have a role in the treatment of arthritic diseases. The development of matrix metalloproteinase inhibitors and their role as potential therapies are also discussed, especially in the light of the disappointing human trials data so far published.

Mediators of periodontal osseous destruction and remodeling: principles and implications for diagnosis and therapy

Osteoclastic bone resorption is a prominent feature of periodontal disease. Bone resorption via osteoclasts and bone formation via osteoblasts are coupled, and their dysregulation is associated with numerous diseases of the skeletal system. Recent developments in the area of mediators of osteoclastic differentiation have expanded our knowledge of the process of resorption and set the stage for new diagnostic and therapeutic modalities to treat situations of localized bone loss as in periodontal disease. This review describes the current state of knowledge of osteoclast differentiation and activity, mediators, and biochemical markers of bone resorption and their use and potential use in clinical periodontics. Finally, therapeutic strategies based on knowledge gained in the treatment of metabolic bone diseases and in periodontal clinical trials are discussed, and the potential for future strategies is proposed relative to their biologic basis. The intent is to update the field of periodontics on the current state of pathophysiology of the osteoclastic lesion and outline diagnostic and therapeutic strategies with a rational basis in the underlying biology.

Modulation of the host response in periodontal therapy

This paper was prepared by the Research, Science, and Therapy Committee of the American Academy of Periodontology to provide the dental profession an overview of current and potential methods to modulate the host response in the treatment of periodontal diseases. Specifically, it discusses components of periodontal disease pathogenesis (i.e., immune and inflammatory responses, excessive production of matrix metalloproteinases and arachidonic acid metabolites, and regulation of bone metabolism) and their modulation.

Bisphosphonates inhibit stromelysin-1 (MMP-3), matrix metalloelastase (MMP-12), collagenase-3 (MMP-13) and enamelysin (MMP-20), but not urokinase-type plasminogen activator, and diminish invasion and migration of human malignant and endothelial cell lines

Bisphosphonates (clodronate, alendronate, pamidronate and zoledronate) at therapeutically attainable non-cytotoxic concentrations inhibited MMP-3, -12, -13 and -20 as well as MMP-1, -2, -8 and -9, but not urokinase-type plasminogen activator (uPA), a serine proteinase and a pro-MMP activator. Dose-dependent inhibition was shown by three independent MMP assays. The inhibition was reduced in the presence of an increased concentration of Ca(2+) when compared to physiologic Ca(2+) concentration. Alendronate inhibited the in vitro invasion (Matrigel) of human HT1080 fibrosarcoma and C8161 melanoma cells, and the random migration of these malignant and endothelial cell lines capable of expressing MMPs and uPA. The concentration of alendronate required to inhibit 50% of the activity (IC(50)=40-70 microM) of MMPs corresponded to the IC(50) of down-regulation of in vitro invasion and migration. The ability of bisphosphonates to down-regulate the in vitro invasion and random migration was comparable or slightly better in relation to the selective gelatinase inhibitor CTTHWGFTLC peptide. Alendronate but not CTTHWGFTLC peptide promoted the adhesion of HT1080 fibrosarcoma and C8161 melanoma cell lines on fibronectin. Bisphosphonates are broad-spectrum MMP inhibitors and this inhibition involves cation chelation. Bisphosphonates further exert antimetastatic, anti-invasive and cell adhesion-promoting properties, which may prevent metastases not only into hard tissues but also to soft tissues.

A combination of a chemically modified doxycycline and a bisphosphonate synergistically inhibits endotoxin-induced periodontal breakdown in rats

BACKGROUND

Chemically modified non-antimicrobial tetracyclines (CMTs) have been shown to inhibit pathologically elevated collagenase (and other matrix metalloproteinase, MMP) activity and bone resorption in vivo and in vitro.

METHODS

In the current study, suboptimal doses of CMT-8 (a non-antimicrobial chemically modified doxycycline) and a bisphosphonate (clodronate, an anti-bone resorption compound) were administered daily, either as a single agent or as a combination therapy, to rats with experimental periodontitis induced by repeated injection of bacterial endotoxin (LPS) into the gingiva. At the end of the 1-week protocol, the gingival tissues were dissected, extracted, and the extracts analyzed for MMPs (collagenases and gelatinases) and for elastase, and the defleshed jaws were morphometrically analyzed for alveolar bone loss.

RESULTS

LPS injection significantly (P<0.001) increased alveolar bone loss and increased collagenase (MMP-8), gelatinase (MMP-9), and elastase activities. Treatment of the LPS-injected rats with suboptimal CMT-8 alone or suboptimal clodronate alone produced slight reductions in the tissue-destructive proteinases and no significant reductions in alveolar bone loss. However, a combination of suboptimal CMT-8 and clodronate "normalized" the pathologically elevated levels of MMPs, elastase, and alveolar bone loss, indicating synergistic inhibition of tissue breakdown in this animal model of periodontitis.

CONCLUSIONS

Combination of a CMT and a bisphosphonate may be a useful treatment to optimally suppress periodontal destruction and tooth loss and in other tissue-destructive inflammatory diseases such as arthritis.