Doxycycline effects on serum bone biomarkers in post-menopausal women

Effects of amoxicillin and metronidazole as an adjunct to scaling and root planing on glycemic control in patients with periodontitis and type 2 diabetes: A short-term randomized controlled trial

OBJECTIVE

To assess the effects of amoxicillin and metronidazole with scaling and root planing (SRP) on periodontal parameters and glycemic control in patients with severe periodontitis and diabetes mellitus.

BACKGROUND

Adjunctive antibiotics use is advantageous for treating periodontitis in patients with severe periodontitis and diabetes. However, the effects of adjunctive antibiotic use on hemoglobin A1c (HbA1c) levels remain unclear.

METHODS

This short-term, randomized controlled trial enrolled patients with severe periodontitis and type 2 diabetes. The patients were randomly allocated to SPR only (i.e., control) or SPR + antibiotics (500 mg of amoxicillin and 200 mg of metronidazole, three times daily for 7 days) groups. Periodontal and hematological parameters were assessed at baseline and 3 months after treatment. Inter- and intra-group analyses were performed using Student's t-tests, Mann-Whitney U tests, and the binary logistic regression models. p-values of <.05 were considered statistically significant.

RESULTS

This study enrolled 49 patients, with 23 and 26 patients in the SRP-only and SRP + antibiotics groups, respectively. The periodontal parameters improved significantly and similarly in both groups after treatment (p < .05). The SRP + antibiotics group had more sites of improvement than the SRP-only group when the initial probing depth was >6 mm. (698 [78.96%] vs. 545 [73.35%], p = .008). The HbA1c levels decreased in the SRP-only and SRP + antibiotics groups after treatment (0.39% and 0.53%, respectively). The multivariable binary logistic regression model demonstrated that antibiotics administration and a high baseline HbA1c level were associated with a greater reduction in the HbA1c level (odds ratio = 4.551, 95% confidence interval: 1.012-20.463; odds ratio = 7.162, 95% confidence interval: 1.359-37.753, respectively).

CONCLUSIONS

SRP and SRP plus systemic antibiotics were beneficial for glycemic control. Adjunctive antibiotic use slightly improved the outcome for patients with severe periodontitis and poorly controlled diabetes.

MicroRNA-101a enhances trabecular bone accrual in male mice

High-throughput microRNA sequencing was performed during differentiation of MC3T3-E1 osteoblasts to develop working hypotheses for specific microRNAs that control osteogenesis. The expression data show that miR-101a, which targets the mRNAs for the epigenetic enzyme Ezh2 and many other proteins, is highly upregulated during osteoblast differentiation and robustly expressed in mouse calvaria. Transient elevation of miR-101a suppresses Ezh2 levels, reduces tri-methylation of lysine 27 in histone 3 (H3K27me3; a heterochromatic mark catalyzed by Ezh2), and accelerates mineralization of MC3T3-E1 osteoblasts. We also examined skeletal phenotypes of an inducible miR-101a transgene under direct control of doxycycline administration. Experimental controls and mir-101a over-expressing mice were exposed to doxycycline in utero and postnatally (up to 8 weeks of age) to maximize penetrance of skeletal phenotypes. Male mice that over-express miR-101a have increased total body weight and longer femora. MicroCT analysis indicate that these mice have increased trabecular bone volume fraction, trabecular number and trabecular thickness with reduced trabecular spacing as compared to controls. Histomorphometric analysis demonstrates a significant reduction in osteoid volume to bone volume and osteoid surface to bone surface. Remarkably, while female mice also exhibit a significant increase in bone length, no significant changes were noted by microCT (trabecular bone parameters) and histomorphometry (osteoid parameters). Hence, miR-101a upregulation during osteoblast maturation and the concomitant reduction in Ezh2 mediated H3K27me3 levels may contribute to the enhanced trabecular bone parameters in male mice. However, the sex-specific effect of miR-101a indicates that more intricate epigenetic mechanisms mediate physiological control of bone formation and homeostasis.

Modulating the Immune Response in Periodontitis

Periodontitis is a chronic inflammatory condition initiated by the accumulation of bacterial biofilm. It is highly prevalent and when left untreated can lead to tooth loss. The presence of bacterial biofilm is essential for the initiation of the inflammatory response but is not the sole initiator. Currently it is unknown which mechanisms drive the dysbiosis of the bacterial biofilm leading to the dysregulation of the inflammatory response. Other players in this equation include environmental, systemic, and genetic factors which can play a role in exacerbating the inflammatory response. Treatment of periodontal disease consists of removal of the bacterial biofilm with the goal of resolving the inflammatory response; however, this does not occur in every case. Understanding the way the inflammatory response does not return to a state of homeostasis has led investigators to consider both systemic and local pharmacological interventions. Nonetheless, a better understanding of the impact that genetics and environmental factors may have on the inflammatory response could be key to helping identify how inflammation can be modulated therefore stopping the destruction of the periodontium. In this article, we will explore the current evidence associating the microbial dysbiosis and the dysregulation of the immune response, potential mechanisms or pathways that may be targeted for the modulation of the inflammatory response, and discuss the advantages and drawbacks associated with local and systemic inflammatory modulation in the management of periodontal disease. This information will be valuable for those interested in understanding potential adjunct methods for managing periodontal diseases, but not limited to, dental professionals, clinical researchers and the public at large.

The effect of choline-stabilized orthosilicic acid in patients with peri-implantitis: an exploratory randomized, double-blind, placebo controlled study

Background

Choline-stabilized orthosilicic acid (CS-OSA) was previously found to stimulate bone collagen formation in osteopenia and to improve biomarkers of cartilage degradation in knee osteoarthritis. The aim of the present study was to investigate the effect of oral administration of CS-OSA on clinical symptoms of peri-implantitis and the associated bone loss.

Methods

Twenty-one patients with peri-implantitis were randomized in CS-OSA or placebo groups. After initial clinical and cone beam computed tomography (CBCT) measurements [probing pocket depth (PPD), bleeding on probing (BOP), mucosal recession (REC), distance from implant shoulder to alveolar crest (IS-AC) and distance from implant shoulder to first bone-to-implant contact (IS-BIC)], flap operations were performed at the peri-implantitis sites. All patients were instructed to use either placebo or CS-OSA capsules twice a day for 1 year. Measurements were repeated 6 and 12 months after randomization.

Results

The data of 18 patients (36 implants) were used in the per protocol analysis. PPD and BOP improved significantly (p < 0.05) compared to baseline for both groups after 6 and 12 months. However, REC significantly increased in the placebo group but not in the CS-OSA group. The change in REC over 6 and 12 months was significantly different between groups (p < 0.01). IS-BIC and IS-AC measurements remained stable in the CS-OSA group whereas in the placebo group, both parameters increased significantly after 6 and 12 months. The change in IS-BIC over 12 months was significantly different between groups (p < 0.05).

Conclusion

The results of this preliminary study suggest that CS-OSA may stabilize and even prevent further bone loss after surgical peri-implantitis treatment and support mucosal tissue healing.

Trial registration

The trial was retrospectively registered at ISRCTN registry, registration number: ISRCTN14348802, registration date: 24/06/2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01817-4.

Antibacterial calcium phosphate cement with human periodontal ligament stem cell-microbeads to enhance bone regeneration and combat infection

Infectious bone defects remain a significant challenge in orthopedics and dentistry. Calcium phosphate cement (CPC) have attracted significant interest in use as local drug delivery system, which with great potential to control release of antibiotics for the treatment of infectious bone defects. Within the current study, a novel antibacterial scaffold of chitosan-reinforced calcium phosphate cement delivering doxycycline hyclate (CPCC + DOX) was developed. Furthermore, the capacity of CPCC + DOX scaffolds for bone regeneration was enhanced by the human periodontal ligament stem cells (hPDLSCs) encapsulated in alginate beads. CPCC + DOX scaffolds were fabricated to contain different concentrations of DOX. Flexural strength of CPCC + DOX ranged from 5.56 ± 0.70 to 6.2 ± 0.72 MPa, which exceeded the reported strength of cancellous bone. Scaffolds exhibited continual DOX release, reaching 80% at 21 days. Scaffold with 5 mg/ml DOX (CPCC + DOX5mg) had a strong antibacterial effect, with a 4-log colony forming unit reduction against S. aureus and P. gingivalis. The proliferation and osteogenic differentiation of hPDLSCs encapsulated in alginate hydrogel microbeads were investigated in culture with CPCC + DOX scaffolds. CPCC + DOX5mg had no negative effect on proliferation of hPDLSCs. Alkaline phosphatase activity, mineral synthesis, and osteogenic gene expressions for CPCC + DOX5mg group were much higher than control group. DOX did not compromise the osteogenic induction. In summary, the novel CPCC + DOX scaffold exhibited excellent mechanical properties and strong antibacterial activity, while supporting the proliferation and osteogenic differentiation of hPDLSCs. The CPCC + DOX + hPDLSCs construct is promising to enhance bone regeneration and combat bone infections in dental, craniofacial, and orthopedic applications.

Doxycycline restores the impaired osteogenic commitment of diabetic-derived bone marrow mesenchymal stromal cells by increasing the canonical WNT signaling

Diabetes mellitus comprehends a group of chronic metabolic disorders, associated with damage and dysfunction of distinct tissues, including bone. At the cellular level, an impaired osteoblastogenesis has been reported, affecting the viability, proliferation and functionality of osteoblasts and precursor populations, hampering the bone metabolic activity, remodeling and healing. Tetracyclines embrace a group of broad-spectrum antibacterial compounds with potential anabolic effects on the bone tissue, through antibacterial-independent mechanisms. Accordingly, this study aims to address the modulatory capability and associated molecular signaling of a low dosage doxycycline - a semi-synthetic tetracycline, in the functional activity of osteoblastic progenitor cells (bone marrow-derived mesenchymal stromal cells), established from a translational diabetic experimental model. Bone marrow-derived mesenchymal stromal cells were isolated from streptozotocin-induced diabetic Wistar rat with proven osteopenia. Cultures were characterized, in the presence of doxycycline (1 μg ml^-1) for proliferation, metabolic activity, apoptosis, collagen synthesis and relevant gene expression with the osteogenic and adipogenic program. The activation of the Wnt/β-catenin pathway was further detailed. Doxycycline normalized the viability, proliferation and metabolic activity of the established cultures, further decreasing cell apoptosis, to levels similar to control. The addition of this drug to the culture environment further increased the osteogenic activation, upregulating the expression of osteogenic markers and collagen synthesis, at the same time that a decreased adipogenic priming was attained. These processes were found to me mediated, at least in part, by the restoration of the signaling through the Wnt/β-catenin pathway.

Periodontal therapeutics: Current host-modulation agents and future directions

With the recognition in the 1960s and 1970s of the periodontopathic importance of the microbial biofilm and its specific anaerobic microorganisms, periodontitis was treated as an infectious disease (more recently, as a dysbiosis). Subsequently, in the 1980s, host-response mechanisms were identified as the mediators of the destruction of the collagen-rich periodontal tissues (gingiva, periodontal ligament, alveolar bone), and the periodontopathogens were now regarded as the "trigger" of the inflammatory/collagenolytic response that characterizes actively destructive periodontitis. Also at this time a new pharmacologic strategy emerged, entitled "host-modulation therapy", based on 2 major findings: (1) that the ability of tetracycline antibiotics to inhibit periodontal breakdown was due (in large part) to their previously unrecognized ability to inhibit the host-derived matrix metalloproteinases (notably, the collagenases, gelatinases, macrophage metalloelastase), and by mechanisms unrelated to the antimicrobial properties of these medications; and (2) that nonsteroidal anti-inflammatory drugs, such as flurbiprofen, again by nonantimicrobial mechanisms, could reduce the severity of periodontitis (however, the adverse effects of long-term therapy precluded their development as safe and effective host-modulatory agents). Additional mechanistic studies resulted in the development of novel nonantimicrobial formulations (Periostat® [now generic] and Oracea®) and compositions of tetracyclines (notably chemically modified tetracycline-3) as host-modulator drugs for periodontitis, arthritis, cardiovascular and pulmonary diseases, cancer, and, more recently, for local and systemic bone loss in postmenopausal women. Identification of the cation-binding active site in the tetraphenolic chemically modified tetracycline molecules drove the development of a new category of matrix metalloproteinase-inhibitor compounds, with a similar active site, the biphenolic chemically modified curcumins. A lead compound, chemically modified curcumin 2.24, has demonstrated safety and efficacy in vitro, in cell culture, and in vivo in mouse, rat, rabbit, and dog models of disease. In conclusion, novel host-modulation compounds have shown significant promise as adjuncts to traditional local therapy in the clinical management of periodontal disease; appear to reduce systemic complications of this all-too-common "inflammatory/collagenolytic" disease; and Oracea® is now commonly prescribed for inflammatory dermatologic diseases.

Doxycycline reduces osteopenia in female rats

Doxycycline, a member of the tetracycline family, is a drug used as an antibiotic (dosage of 100 mg/day) and as an anti-inflammatory drug on the dosage of 20 mg twice a day, this use has Matrix Metalloproteinases (MMP) inhibitor action. Doxycycline is a calcium chelator and therefore interferes in bone remodeling. The main objective of this study was to evaluate the action of the drug doxycycline in the control of osteopenia. Sixty three Wistars rats were divided into 9 groups with n = 7 each, as follow: the control group with doxycycline 10 mg/kg/day (C10), control with doxycycline 30 mg/kg/day (C30) and control (C), ovariectomized group with doxycycline 10 mg/kg/day (OVX10), ovariectomized with doxycycline 30 mg/kg/day (OVX30), and ovariectomized with water (OVX), sedentary group with 10 mg/kg/day (Se10), sedentary with doxycycline 30 mg/kg/day (Se30), and sedentary group with water (Se). Left femoral bone was used for bone densitometry, right femoral bone for histological analysis. The right tibia was intended for chemical quantifications, the total serum was used for cholesterol and calcium quantification. The length of the left femoral bone was measured after the densitometry analysis. Statistical analysis was performed using multivariate general linear model (ANOVA two factors with Bonferroni adjustment) and the TRAP analysis was subjected to normality test and then were subjected to nonparametric test, both with p < 0.05 significance. Statistically significant differences were found, with better results for the groups exposed to the medication (10 and 30 mg/kg/day): Se vs. Se10 and Se vs. Se30 for BMC, quantification of magnesium, amount of cancellous bone in the distal portion; OVX vs. OVX10 for BMC, BMD and calcium in serum; OVX vs. OVX10 and OVX30 for quantification in proximal and distal portion of cancellous bone; Se vs. Se30 and OVX vs. OVX30 for immunostaining for TRAP, all results with minimum of p ≤ 0.05. Doxycycline had a deleterious effect on control groups and positive action for bone organization on female rats affected by bilateral ovariectomy-induced osteopenia and sedentary lifestyle.

Loss of alveolar bone density in postmenopausal, osteopenic women is associated with circulating levels of gelatinases

OBJECTIVE

To determine whether circulating levels of two matrix metalloproteinases, MMP-2 and MMP-9, are associated with loss of alveolar bone density (ABD) or height (ABH), or with progression of periodontitis (relative clinical attachment level [RCAL]), among postmenopausal women with local and systemic bone loss.

BACKGROUND

This study was planned as part of a 2-year randomized, double-blind, placebo-controlled, clinical trial examining efficacy/safety of subantimicrobial dose doxycycline (20 mg bid) in postmenopausal osteopenic women. This study examines whether serum levels of gelatinases are associated with local changes in the periodontium.

METHODS

A sample of 113 women received periodontal maintenance for moderate to advanced chronic periodontitis and consented to analysis of stored serum biomarkers. Posterior vertical bitewings were taken, and serum collected, at baseline, one, and 2 years. ABD was determined by computer-assisted densitometric image analysis (CADIA), ABH by the Hausmann et al (1992, J Periodontol 63, 657) method, and RCAL by Florida Probe (every 6 months). MMPs were measured densitometrically on gelatin zymograms using denatured type I collagen as substrate and purified MMP-2 (72 kDa) and MMP-9 (92 kDa) as standards. Evidence of worsening in the periodontium at a tooth site was defined as a change from baseline of, for ABD, at least 14 densitometric units (for subcrestal locations) or 17 units (for crestal locations); of at least 0.4 mm for ABH; and of at least 1.5 mm for RCAL. Logistic regression models, while accounting for clustering, compared the odds of worsening in ABD, ABH, or RCAL, after 2 years of observation, between groups defined by baseline and concurrent levels of serum gelatinases.

RESULTS

Changes in ABH and RCAL were not associated with circulating levels of MMP-2 or MMP-9. However, elevated odds of ABD loss over 24 months were associated, among smokers, with both baseline and concurrent levels of MMP-9 in the middle and highest tertile, and with concurrent levels of MMP-2 in the middle (but not the highest) tertile. Elevated odds of ABD loss were also associated, among women within 5 years of menopause, with baseline levels of MMP-2 in the highest tertile.

CONCLUSION

Among postmenopausal osteopenic women, loss of ABD was associated, in smokers, with elevated circulating levels of MMP-9 and MMP-2. In those within 5 years of menopause, ABD loss was associated with elevated circulating levels of MMP-2.

Supportive periodontal therapy (SPT) for maintaining the dentition in adults treated for periodontitis

BACKGROUND

Periodontitis is a bacterially-induced, chronic inflammatory disease that destroys the connective tissues and bone that support teeth. Active periodontal treatment aims to reduce the inflammatory response, primarily through eradication of bacterial deposits. Following completion of treatment and arrest of inflammation, supportive periodontal therapy (SPT) is employed to reduce the probability of re-infection and progression of the disease; to maintain teeth without pain, excessive mobility or persistent infection in the long term, and to prevent related oral diseases.According to the American Academy of Periodontology, SPT should include all components of a typical dental recall examination, and importantly should also include periodontal re-evaluation and risk assessment, supragingival and subgingival removal of bacterial plaque and calculus, and re-treatment of any sites showing recurrent or persistent disease. While the first four points might be expected to form part of the routine examination appointment for periodontally healthy patients, the inclusion of thorough periodontal evaluation, risk assessment and subsequent treatment - normally including mechanical debridement of any plaque or calculus deposits - differentiates SPT from routine care.Success of SPT has been reported in a number of long-term, retrospective studies. This review aimed to assess the evidence available from randomised controlled trials (RCTs).

OBJECTIVES

To determine the effects of supportive periodontal therapy (SPT) in the maintenance of the dentition of adults treated for periodontitis.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 8 May 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2017, Issue 5), MEDLINE Ovid (1946 to 8 May 2017), and Embase Ovid (1980 to 8 May 2017). The US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

Randomised controlled trials (RCTs) evaluating SPT versus monitoring only or alternative approaches to mechanical debridement; SPT alone versus SPT with adjunctive interventions; different approaches to or providers of SPT; and different time intervals for SPT delivery.We excluded split-mouth studies where we considered there could be a risk of contamination.Participants must have completed active periodontal therapy at least six months prior to randomisation and be enrolled in an SPT programme. Trials must have had a minimum follow-up period of 12 months.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened search results to identify studies for inclusion, assessed the risk of bias in included studies and extracted study data. When possible, we calculated mean differences (MDs) and 95% confidence intervals (CIs) for continuous variables. Two review authors assessed the quality of evidence for each comparison and outcome using GRADE criteria.

MAIN RESULTS

We included four trials involving 307 participants aged 31 to 85 years, who had been previously treated for moderate to severe chronic periodontitis. Three studies compared adjuncts to mechanical debridement in SPT versus debridement only. The adjuncts were local antibiotics in two studies (one at high risk of bias and one at low risk) and photodynamic therapy in one study (at unclear risk of bias). One study at high risk of bias compared provision of SPT by a specialist versus general practitioner. We did not identify any RCTs evaluating the effects of SPT versus monitoring only, or of providing SPT at different time intervals, or that compared the effects of mechanical debridement using different approaches or technologies.No included trials measured our primary outcome 'tooth loss'; however, studies evaluated signs of inflammation and potential periodontal disease progression, including bleeding on probing (BoP), clinical attachment level (CAL) and probing pocket depth (PPD).There was no evidence of a difference between SPT delivered by a specialist versus a general practitioner for BoP or PPD at 12 months (very low-quality evidence). This study did not measure CAL or adverse events.Due to heterogeneous outcome reporting, it was not possible to combine data from the two studies comparing mechanical debridement with or without the use of adjunctive local antibiotics. Both studies found no evidence of a difference between groups at 12 months (low to very low-quality evidence). There were no adverse events in either study.The use of adjunctive photodynamic therapy did not demonstrate evidence of benefit compared to mechanical debridement only (very low-quality evidence). Adverse events were not measured.The quality of the evidence is low to very low for these comparisons. Future research is likely to change the findings, therefore the results should be interpreted with caution.

AUTHORS' CONCLUSIONS

Overall, there is insufficient evidence to determine the superiority of different protocols or adjunctive strategies to improve tooth maintenance during SPT. No trials evaluated SPT versus monitoring only. The evidence available for the comparisons evaluated is of low to very low quality, and hampered by dissimilarities in outcome reporting. More trials using uniform definitions and outcomes are required to address the objectives of this review.

A minocycline-releasing PMMA system as a space maintainer for staged bone reconstructions-in vitro antibacterial, cytocompatibility and anti-inflammatory characterization

In the present work, we study the development and biological characterization of a polymethyl methacrylate (PMMA)-based minocycline delivery system, to be used as a space maintainer within craniofacial staged regenerative interventions. The developed delivery systems were characterized regarding solid state characteristics and assayed in vitro for antibacterial and anti-inflammatory activity, and cytocompatibility with human bone cells. A drug release profile allowed for an initial burst release and a more sustained and controlled release over time, with minimum inhibitory concentrations for the assayed and relevant pathogenic bacteria (i.e., Staphylococcus aureus, slime-producer Staphylococcus epidermidis and Escherichia coli) being easily attained in the early time points, and sustained up to 72 h. Furthermore, an improved osteoblastic cell response-with enhancement of cell adhesion and cell proliferation-and increased anti-inflammatory activity were verified in developed systems, compared to a control (non minocycline-loaded PMMA cement). The obtained results converge to support the possible efficacy of the developed PMMA-based minocycline delivery systems for the clinical management of complex craniofacial trauma. Here, biomaterials with space maintenance properties are necessary for the management of staged reconstructive approaches, thus minimizing the risk of peri-operative infections and enhancing the local tissue healing and early stages of regeneration.

Non-antibacterial tetracycline formulations: host-modulators in the treatment of periodontitis and relevant systemic diseases

Traditionally, the dental profession has primarily treated periodontitis using a mechanical/surgical, rather than a pharmaceutical, approach. However, based on experiments several decades ago which demonstrated that tetracyclines, unexpectedly, inhibit collagen- and bone-destructive mammalian-derived enzymes (e.g. the collagenases), and through non-antibiotic mechanisms, the concept of host-modulation therapy (HMT) was developed. Accordingly, two drug-development strategies evolved: (i) the development of non-antimicrobial formulations of doxycycline; and (ii) the chemical modification of tetracyclines to eliminate their antibiotic activity but retain (or even enhance) their anti-collagenase properties. Regarding the latter, these chemically modified tetracyclines (CMTs) showed efficacy in vitro, in animal models of periodontal (and relevant systemic) disease, and in preliminary clinical trials on patients with Kaposi's sarcoma (however, at the high doses used, photosensitivity was a significant side-effect). In the first strategy, subantimicrobial-dose doxycycline (SDD) demonstrated safety and efficacy in human clinical trials and was approved by the U S Food and Drug Administration (U S FDA) and in other countries for the treatment of periodontitis (20 mg, twice daily, i.e. once every 12 hours) adjunctive to scaling and root planing, and for chronic inflammatory skin diseases (40-mg sustained-release 'beads'). SDD also showed efficacy in patients with systemic diseases relevant to periodontitis, including diabetes mellitus and arthritis, and in postmenopausal women with local and systemic bone loss. Importantly, long-term administration of SDD, of up to 2 years, in clinical trials did not produce antibiotic side-effects. SDD (and in the future, new HMTs, such as low-dose CMT-3, resolvins and chemically modified curcumins) may shift the paradigm of periodontal therapy from a predominantly surgical approach to the greater use of medicinal/pharmacologic strategies, ultimately to benefit larger numbers of patients.

A novel chemically modified curcumin reduces inflammation-mediated connective tissue breakdown in a rat model of diabetes: periodontal and systemic effects

BACKGROUND AND OBJECTIVE

Periodontal disease is the most common chronic inflammatory disease known to mankind (and the major cause of tooth loss in the adult population) and has also been linked to various systemic diseases, particularly diabetes mellitus. Based on the literature linking periodontal disease with diabetes in a "bidirectional manner", the objectives of the current study were to determine: (i) the effect of a model of periodontitis, complicated by diabetes, on mechanisms of tissue breakdown including bone loss; and (ii) the response of the combination of this local and systemic phenotype to a novel pleiotropic matrix metalloproteinase inhibitor, chemically modified curcumin (CMC) 2.24.

MATERIAL AND METHODS

Diabetes was induced in adult male rats by intravenous injection of streptozotocin (nondiabetic rats served as controls), and Escherichia coli endotoxin (lipopolysaccharide) was repeatedly injected into the gingiva to induce periodontitis. CMC 2.24 was administered by oral gavage (30 mg/kg) daily; untreated diabetic rats received vehicle alone. After 3 wk of treatment, the rats were killed, and gingiva, jaws, tibia and skin were collected. The maxillary jaws and tibia were dissected and radiographed. The gingival tissues of each experimental group (n = 6 rats/group) were pooled, extracted, partially purified and, together with individual skin samples, analyzed for matrix metalloproteinase (MMP)-2 and MMP-9 by gelatin zymography; MMP-8 was analyzed in gingival and skin tissue extracts, and in serum, by western blotting. The levels of three bone-resorptive cytokines [interleukin (IL)-1β, IL-6 and tumor necrosis factor-α], were measured in gingival tissue extracts and serum by ELISA.

RESULTS

Systemic administration of CMC 2.24 to diabetic rats with endotoxin-induced periodontitis significantly inhibited alveolar bone loss and attenuated the severity of local and systemic inflammation. Moreover, this novel tri-ketonic phenylaminocarbonyl curcumin (CMC 2.24) appeared to reduce the pathologically excessive levels of inducible MMPs to near-normal levels, but appeared to have no significant effect on the constitutive MMPs required for physiologic connective tissue turnover. In addition to the beneficial effects on periodontal disease, induced both locally and systemically, CMC 2.24 also favorably affected extra-oral connective tissues, skin and skeletal bone.

CONCLUSION

This study supports our hypothesis that CMC 2.24 is a potential therapeutic pleiotropic MMP inhibitor, with both intracellular and extracellular effects, which reduces local and systemic inflammation and prevents hyperglycemia- and bacteria-induced connective tissue destruction.

Non-surgical periodontal therapy: An update on current evidence

Periodontal disease is an inflammatory condition that involves a complex interaction between pathogenic bacteria, environmental and acquired factors and host related factors. Till recently periodontal treatment was directed primarily towards reduction of bacterial load by subgingival debridement of root surfaces and modification of environmental risk factors. The current paradigm of periodontal disease stresses greater role of host-mediated inflammatory response in tissue destruction characteristic of periodontal disease. Various therapeutic modalities have been developed adjuvant to mechanical periodontal therapy. The use of laser and photodynamic therapy show great promise but their effectiveness has still not been conclusively proven. Chemotherapeutic agents, either systemic and local antimicrobials or host modulating drugs, played pivotal role in better and more predictable management of periodontal disease. The present review focuses on the best available evidence, for the current management of the chronic periodontal patients, gathered from systematic reviews and meta-analysis of mechanical non surgical periodontal therapy (NSPT) (subgingival debridement, laser therapy and photodynamic therapy) and the adjunctive chemotherapeutic approaches such as systematic and local antibiotics and antiseptics, subgingival pocket irrigation and host modulation therapies. The review also attempts to briefly introduce future developments in some of these modalities. At the end, the review summarizes the analysis of the current evidence that suggests that thorough subgingival debridement remains the mainstay of NSPT and that adjunct use of chemotherapeutic agents may offer better management of clinical parameters in periodontitis patients.

A novel chemically modified curcumin reduces severity of experimental periodontal disease in rats: initial observations

Tetracycline-based matrix metalloproteinase- (MMP-) inhibitors are currently approved for two inflammatory diseases, periodontitis and rosacea. The current study addresses the therapeutic potential of a novel pleiotropic MMP-inhibitor not based on an antibiotic. To induce experimental periodontitis, endotoxin (LPS) was repeatedly injected into the gingiva of rats on one side of the maxilla; the contralateral (control) side received saline injections. Two groups of rats were treated by daily oral intubation with a chemically modified curcumin, CMC 2.24, for two weeks; the control groups received vehicle alone. After sacrifice, gingiva, blood, and maxilla were collected, the jaws were defleshed, and periodontal (alveolar) bone loss was quantified morphometrically and by μ-CT scan. The gingivae were pooled per experimental group, extracted, and analyzed for MMPs (gelatin zymography; western blot) and for cytokines (e.g., IL-1β; ELISA); serum and plasma samples were analyzed for cytokines and MMP-8. The LPS-induced pathologically excessive bone loss was reduced to normal levels based on either morphometric (P = 0.003) or μ-CT (P = 0.008) analysis. A similar response was seen for MMPs and cytokines in the gingiva and blood. This initial study, on a novel triketonic zinc-binding CMC, indicates potential efficacy on inflammatory mediators and alveolar bone loss in experimental periodontitis and warrants future therapeutic and pharmacokinetic investigations.

Anti-inflammatory Actions of Adjunctive Tetracyclines and Other Agents in Periodontitis and Associated Comorbidities

The non-antimicrobial properties of tetracyclines such as anti-inflammatory, proanabolic and anti-catabolic actions make them effective pharmaceuticals for the adjunctive management of chronic inflammatory diseases. An over-exuberant inflammatory response to an antigenic trigger in periodontitis and other chronic inflammatory diseases could contribute to an autoimmune element in disease progression. Their adjunctive use in managing periodontitis could have beneficial effects in curbing excessive inflammatory loading from commonly associated comorbidities such as CHD, DM and arthritis. Actions of tetracyclines and their derivatives include interactions with MMPs, tissue inhibitors of MMPs, growth factors and cytokines. They affect the sequence of inflammation with implications on immunomodulation, cell proliferation and angiogenesis; these actions enhance their scope, in treating a range of disease entities. Non-antimicrobial chemically modified tetracyclines (CMTs) sustain their diverse actions in organ systems which include anti-inflammatory, anti-apoptotic, anti-proteolytic actions, inhibition of angiogenesis and tumor metastasis. A spectrum of biological actions in dermatitis, periodontitis, atherosclerosis, diabetes, arthritis, inflammatory bowel disease, malignancy and prevention of bone resorption is particularly relevant to minocycline. Experimental models of ischemia indicate their specific beneficial effects. Parallel molecules with similar functions, improved Zn binding and solubility have been developed for reducing excessive MMP activity. Curbing excessive MMP activity is particularly relevant to periodontitis, and comorbidities addressed here, where specificity is paramount. Unique actions of tetracyclines in a milieu of excessive inflammatory stimuli make them effective therapeutic adjuncts in the management of chronic inflammatory disorders. These beneficial actions of tetracyclines are relevant to the adjunctive management of periodontitis subjects presenting with commonly prevalent comorbidities addressed here.

Perioceutics: Matrix metalloproteinase inhibitors as an adjunctive therapy for inflammatory periodontal disease

Matrix metalloproteinases (MMPs) form a group of more than 20 zinc-dependent enzymes that are crucial in the degradation of the main components in the extracellular matrix, and thereby play important roles in cell migration, wound healing, and tissue remodeling. MMPs have outgrown the field of extracellular matrix biology and have progressed toward being important regulatory molecules in inflammation, and hence are key components in the pathogenesis of periodontitis. This rise in status has led to the development of MMP inhibitors which can act as switches or delicate tuners in acute and chronic inflammation and the regenerative phase after inflammation. The new challenge in MMP research is to better understand the complex role these enzymes play in periodontal disease and to design inhibitors that are successful in the clinic. Perioceutics or the use of the pharmacological agents specifically developed to manage periodontitis is an interesting and emerging aid in the management of periodontal diseases along with mechanical debridement. The purpose of this review is to provide an introduction to MMPs and their inhibitors, the pathologic effects of a disturbance in the functions of enzyme cascades in balance with natural inhibitors, and highlight on the adjunctive use of MMP inhibitors in periodontal therapy and some of the current challenges with an overview of what has been achieved till date.

Non-antibacterial tetracycline formulations: clinical applications in dentistry and medicine

In 1983, it was first reported that tetracyclines (TCs) can modulate the host response, including (but not limited to) inhibition of pathologic matrix metalloproteinase (MMP) activity, and by mechanisms unrelated to the antibacterial properties of these drugs. Soon thereafter, strategies were developed to generate non-antibacterial formulations (subantimicrobial-dose doxycycline; SDD) and compositions (chemically modified tetracyclines; CMTs) of TCs as host-modulating drugs to treat periodontal and other inflammatory diseases. This review focuses on the history and rationale for the development of: (a) SDD which led to two government-approved medications, one for periodontitis and the other for acne/rosacea and (b) CMTs, which led to the identification of the active site of the drugs responsible for MMP inhibition and to studies demonstrating evidence of efficacy of the most potent of these, CMT-3, as an anti-angiogenesis agent in patients with the cancer, Kaposi's sarcoma, and as a potential treatment for a fatal lung disease (acute respiratory distress syndrome; ARDS). In addition, this review discusses a number of clinical studies, some up to 2 years' duration, demonstrating evidence of safety and efficacy of SDD formulations in humans with oral inflammatory diseases (periodontitis, pemphigoid) as well as medical diseases, including rheumatoid arthritis, post-menopausal osteopenia, type II diabetes, cardiovascular diseases, and a rare and fatal lung disease, lymphangioleiomyomatosis.

Tetracyclines convert the osteoclastic-differentiation pathway of progenitor cells to produce dendritic cell-like cells

Tetracyclines, such as doxycycline and minocycline, are used to suppress the growth of bacteria in patients with inflammatory diseases. Tetracyclines have been shown to prevent bone loss, but the mechanism involved is unknown. Osteoclasts and dendritic cells (DCs) are derived from common progenitors, such as bone marrow-derived macrophages (BMMs). In this article, we show that tetracyclines convert the differentiation pathway, resulting in DC-like cells not osteoclasts. Doxycycline and minocycline inhibited the receptor activator of NF-κB ligand (RANKL)-induced osteoclastogenesis of BMMs, but they had no effects on cell growth and phagocytic activity. They influenced neither the proliferation nor the differentiation of bone-forming osteoblasts. Surprisingly, doxycycline and minocycline induced the expression of DC markers, CD11c and CD86, in BMMs in the presence of RANKL. STAT5 is involved in DC differentiation induced by GM-CSF. Midostaurin, a STAT5-signaling inhibitor, and an anti-GM-CSF-neutralizing Ab suppressed the differentiation induced by GM-CSF but not by tetracyclines. In vivo, the injection of tetracyclines into RANKL-injected mice and RANKL-transgenic mice suppressed RANKL-induced osteoclastogenesis and promoted the concomitant appearance of CD11c(+) cells. These results suggested that tetracyclines prevent bone loss induced by local inflammation, including rheumatoid arthritis and periodontitis, through osteoclast-DC-like cell conversion.

Host-derived diagnostic markers related to soft tissue destruction and bone degradation in periodontitis

BACKGROUND

A major challenge in clinical periodontics is to find a reliable molecular marker of periodontal tissue destruction with high sensitivity, specificity and utility.

OBJECTIVES

The aim of this systematic review is to evaluate available literature on 'the utility of molecular markers of soft and hard periodontal tissue destruction'.

MATERIALS AND METHODS

Based on the focused question, 'What is the utility of molecular markers of soft and hard periodontal tissue destruction', an electronic and manual search was conducted for human studies presenting clinical data for the potential of molecular markers of tissue destruction in biofluids; gingival crevicular fluid (GCF), saliva, and serum.

RESULTS

Papers fulfilling the inclusion criteria were selected. All relevant data from the selected papers were extracted and recorded in separate tables for molecules in GCF, saliva, and serum.

CONCLUSION

Within the defined limits of the Problem/Population, Intervention, Comparison, Outcome, the present analysis reveals that (a) no single or combination of markers exists that can disclose periodontal tissue destruction adequately; (b) while the most fruitful source of biomarkers for periodontal destruction appears to be in molecules tightly related to bone and soft tissue destruction, this remains to be objectively demonstrated. Currently, clinical measurements are still the most reliable.

Serum bone biomarkers and oral/systemic bone loss in humans

We recently reported that subantimicrobial-dose doxycycline (SDD) significantly reduced serum bone-resorption biomarkers in subgroups of post-menopausal women. We hypothesize that changes in serum bone biomarkers are associated not only with systemic bone mineral density (BMD) changes, but also with alveolar bone changes over time. One hundred twenty-eight eligible post-menopausal women with periodontitis and systemic osteopenia were randomly assigned to receive SDD or placebo tablets twice daily for two years, adjunctive to periodontal maintenance. Sera were analyzed for bone biomarkers. As expected, two-year changes in a serum bone biomarker were significantly associated with systemic BMD loss at the lumbar spine (osteocalcin, bone-turnover biomarker, p = 0.0002) and femoral neck (osteocalcin p = 0.0025). Two-year changes in serum osteocalcin and serum pyridinoline-crosslink fragment of type I collagen (ICTP; bone-resorption biomarker) were also significantly associated with alveolar bone density loss (p < 0.0001) and alveolar bone height loss (p = 0.0008), respectively. Thus, we have shown that serum bone biomarkers are associated with not only systemic BMD loss, but with alveolar bone loss as well.

CLINICAL TRIAL REGISTRATION INFORMATION

Protocol registered at ClinicalTrials.gov, NCT00066027.

Using tetracyclines to treat osteoporotic/osteopenic bone loss: from the basic science laboratory to the clinic

Periodontitis (progressive inflammatory disease characterized by alveolar bone loss, a major cause of tooth loss worldwide) is associated with both systemic osteoporosis and its milder form, osteopenia. Tetracyclines, by virtue of their non-antimicrobial pro-anabolic and anti-catabolic properties, are excellent candidate pharmaceuticals to simultaneously treat these local and systemic disorders. This paper reviews the foundational basic science and translational research which lead to a pivotal multicenter randomized clinical trial in postmenopausal women with both periodontitis and systemic (skeletal) osteopenia. This trial was designed primarily to examine whether subantimicrobial dose doxycycline (SDD) could reduce progressive alveolar (oral) bone loss associated with periodontitis and, secondarily, whether SDD could reduce systemic bone loss in the same subjects. This paper describes the efficacy and safety findings from this clinical trial and also outlines future directions using this promising and novel approach to manage both oral and systemic bone loss.