Low-dose doxycycline therapy: effect on gingival and crevicular fluid collagenase activity in humans

Modulation of oral cancer and periodontitis using chemotherapeutic agents - A narrative review

Periodontitis, an inflammatory condition, is linked to a higher risk of developing oral cancer. Periodontitis may be a precipitating factor for tumorigenesis and the aggressiveness of specific cancer variants. Although genetics is considered the primary etiologic factor for the development of most cancers, many factors have come to be recognized in the initiation and progression of oral cancer. Consecutively, it is suggestive that periodontitis and oral cancer are distinct disease entities but share common pathogenic mechanisms. Oxidative stress and epigenetic mechanisms are among the most researched mechanisms responsible for initiating apoptotic mechanisms implicated in periodontitis and oral cancer. Current research aims to formulate therapeutic agents to intercede in these mechanisms via host modulation therapy and epigenetic therapy. These advances can revolutionize the treatment of periodontitis and oral cancer. This review aims to shed light on the common pathogenic mechanisms of these diseases and the various host modulation agents that could be beneficial in their treatment.

Matrix Metalloproteinases: From Molecular Mechanisms to Physiology, Pathophysiology, and Pharmacology

The first matrix metalloproteinase (MMP) was discovered in 1962 from the tail of a tadpole by its ability to degrade collagen. As their name suggests, matrix metalloproteinases are proteases capable of remodeling the extracellular matrix. More recently, MMPs have been demonstrated to play numerous additional biologic roles in cell signaling, immune regulation, and transcriptional control, all of which are unrelated to the degradation of the extracellular matrix. In this review, we will present milestones and major discoveries of MMP research, including various clinical trials for the use of MMP inhibitors. We will discuss the reasons behind the failures of most MMP inhibitors for the treatment of cancer and inflammatory diseases. There are still misconceptions about the pathophysiological roles of MMPs and the best strategies to inhibit their detrimental functions. This review aims to discuss MMPs in preclinical models and human pathologies. We will discuss new biochemical tools to track their proteolytic activity in vivo and ex vivo, in addition to future pharmacological alternatives to inhibit their detrimental functions in diseases. SIGNIFICANCE STATEMENT: Matrix metalloproteinases (MMPs) have been implicated in most inflammatory, autoimmune, cancers, and pathogen-mediated diseases. Initially overlooked, MMP contributions can be both beneficial and detrimental in disease progression and resolution. Thousands of MMP substrates have been suggested, and a few hundred have been validated. After more than 60 years of MMP research, there remain intriguing enigmas to solve regarding their biological functions in diseases.

Combined Radiochemotherapy: Metalloproteinases Revisited

Besides cytotoxic DNA damage irradiation of tumor cells triggers multiple intra- and intercellular signaling processes, that are part of a multilayered, treatment-induced stress response at the unicellular and tumor pathophysiological level. These processes are intertwined with intrinsic and acquired resistance mechanisms to the toxic effects of ionizing radiation and thereby co-determine the tumor response to radiotherapy. Proteolysis of structural elements and bioactive signaling moieties represents a major class of posttranslational modifications regulating intra- and intercellular communication. Plasma membrane-located and secreted metalloproteinases comprise a family of metal-, usually zinc-, dependent endopeptidases and sheddases with a broad variety of substrates including components of the extracellular matrix, cyto- and chemokines, growth and pro-angiogenic factors. Thereby, metalloproteinases play an important role in matrix remodeling and auto- and paracrine intercellular communication regulating tumor growth, angiogenesis, immune cell infiltration, tumor cell dissemination, and subsequently the response to cancer treatment. While metalloproteinases have long been identified as promising target structures for anti-cancer agents, previous pharmaceutical approaches mostly failed due to unwanted side effects related to the structural similarities among the multiple family members. Nevertheless, targeting of metalloproteinases still represents an interesting rationale alone and in combination with other treatment modalities. Here, we will give an overview on the role of metalloproteinases in the irradiated tumor microenvironment and discuss the therapeutic potential of using more specific metalloproteinase inhibitors in combination with radiotherapy.

The adjunctive use of host modulators in non-surgical periodontal therapy. A systematic review of randomized, placebo-controlled clinical studies

BACKGROUND

Considering the role of the inflammatory host response in the pathogenesis of periodontitis, different host modulators have been proposed to enhance the outcomes of non-surgical periodontal therapy (NSPT), but their efficacy has not been fully clarified.

OBJECTIVES

This systematic review investigated the efficacy of host modulators combined with NSPT in reducing probing pocket depth (PPD) in periodontitis patients.

MATERIALS AND METHODS

Placebo-controlled RCTs with ≥6 months follow-up were searched. Meta-analysis was conducted when ≥5 studies using the same host modulator were identified.

RESULTS

Fifty eight studies met the inclusion criteria. After 6 months, local administration of 1.2% statin gels as adjuncts to NSPT significantly improved PPD reduction (1.83 mm) in infrabony defects and systemic administration of sub-antimicrobial dose doxycycline (SDD) in addition to NSPT improved PPD reduction of deep pockets. Administration of probiotics conferred limited clinical benefits. Local bisphosphonate and metformin gels showed potential for clinical use in infrabony defects, which needs to be confirmed.

CONCLUSIONS

Local delivery of statins in infrabony defects and systemic SDD for deep pockets may confer additional clinical benefits to NSPT. Their long-term effectiveness and safety need to be confirmed in independent multi-centred studies. Further studies are needed to confirm the benefit of other host modulators.

Efficacy of alternative or additional methods to professional mechanical plaque removal during supportive periodontal therapy: A systematic review and meta-analysis

AIMS

To systematically review the literature addressing the following focused questions: "What is the efficacy of either (#1) alternative or (#2) additional methods to professional mechanical plaque removal (PMPR) on progression of attachment loss during supportive periodontal therapy (SPT) in periodontitis patients?".

METHODS

A systematic search for randomized clinical trials was performed. Change in clinical attachment level (CAL) from baseline was the primary outcome.

RESULTS

Routine PMPR performed with either a combination of ultrasonic/hand instruments or Er:Yag laser showed similarly effective in preventing CAL loss. Moreover, a routine SPT regimen based on PMPR led to stability of CAL irrespective of a daily sub-antimicrobial doxycycline dose (SDD). Finally, an adjunctive photodynamic therapy (PDT) did not enhance the magnitude of CAL gain when sites with probing depth ≥4 mm were repeatedly treated. After pooling all data, the results of the meta-analysis showed no statistical differences in CAL change from baseline: mean overall CAL change was -0.233 mm (95% confidence interval: -1.065, 0.598; p = .351).

CONCLUSIONS

Weak evidence indicate that in treated periodontitis patients enrolled in a 3-4 month SPT based on PMPR, Er:Yag laser (as alternative), SDD and PDT (as additional) do not produce a greater clinical effect on periodontal conditions compared to PMPR.

Targeting MMP-Regulation of Inflammation to Increase Metabolic Tolerance to COVID-19 Pathologies: A Hypothesis

Many individuals infected with the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) develop no or only mild symptoms, but some can go on onto develop a spectrum of pathologies including pneumonia, acute respiratory distress syndrome, respiratory failure, systemic inflammation, and multiorgan failure. Many pathogens, viral and non-viral, can elicit these pathologies, which justifies reconsidering whether the target of therapeutic approaches to fight pathogen infections should be (a) the pathogen itself, (b) the pathologies elicited by the pathogen interaction with the human host, or (c) a combination of both. While little is known about the immunopathology of SARS-CoV-2, it is well-established that the above-mentioned pathologies are associated with hyper-inflammation, tissue damage, and the perturbation of target organ metabolism. Mounting evidence has shown that these processes are regulated by endoproteinases (particularly, matrix metalloproteinases (MMPs)). Here, we review what is known about the roles played by MMPs in the development of COVID-19 and postulate a mechanism by which MMPs could influence energy metabolism in target organs, such as the lung. Finally, we discuss the suitability of MMPs as therapeutic targets to increase the metabolic tolerance of the host to damage inflicted by the pathogen infection, with a focus on SARS-CoV-2.

Macrophage immunomodulation in chronic osteolytic diseases-the case of periodontitis

Periodontitis (PD) is a chronic osteolytic disease that shares pathogenic inflammatory features with other conditions associated with nonresolving inflammation. A hallmark of PD is inflammation-mediated alveolar bone loss. Myeloid cells, in particular polymorphonuclear neutrophils (PMN) and macrophages (Mac), are essential players in PD by control of gingival biofilm pathogenicity, activation of adaptive immunity, as well as nonresolving inflammation and collateral tissue damage. Despite mounting evidence of significant innate immune implications to PD progression and healing after therapy, myeloid cell markers and targets for immune modulation have not been validated for clinical use. The remarkable plasticity of monocytes/Mac in response to local activation factors enables these cells to play central roles in inflammation and restoration of tissue homeostasis and provides opportunities for biomarker and therapeutic target discovery for management of chronic inflammatory conditions, including osteolytic diseases such as PD and arthritis. Along a wide spectrum of activation states ranging from proinflammatory to pro-resolving, Macs respond to environmental changes in a site-specific manner in virtually all tissues. This review summarizes the existing evidence on Mac immunomodulation therapies for osteolytic diseases in the broader context of conditions associated with nonresolving inflammation, and discusses osteoimmune implications of Macs in PD.

Adjunctive Effects of a Sub-Antimicrobial Dose of Doxycycline on Clinical Parameters and Potential Biomarkers of Periodontal Tissue Catabolism

Objectives: The aim of the present randomized, double-blind, placebo-controlled, parallel-arm study was to examine the effectiveness of a sub-antimicrobial dose of doxycycline (SDD) in combination with nonsurgical periodontal therapy, compared to nonsurgical periodontal therapy alone, on potential gingival crevicular fluid (GCF) biomarkers of periodontal tissue catabolism related to the clinical outcomes over a 12-month period. Materials and Methods: GCF was collected and clinical parameters were recorded from 30 periodontitis patients randomized either to an SDD or placebo group. The SDD group received SDD (20 mg) b.i.d for 3 months plus scaling and root planing (SRP), while the placebo group was given placebo capsules b.i.d for 3 months plus SRP. The patients were evaluated every 3 months during the 12-month study period. At each visit, clinical parameters and GCF sampling were repeated. Matrix metalloproteinase (MMP)-8, MMP-9, MMP-13, myeloperoxidase (MPO), osteoprotegerin (OPG), and tartrate-resistant acid phosphatase-5 (TRAP-5) were determined by IFMA and ELISA. Results: Significant improvements were observed in all clinical parameters in both groups over 12 months (p < 0.0125) while the SDD group showed significantly better reduction in gingival index (GI) and pocket depth and a gain in clinical attachment compared to the placebo group (p < 0.05). GCF MMP-8 and OPG levels significantly reduced in the SDD group compared to baseline (p < 0.05). GCF MMP-9 significantly decreased in both groups compared to baseline (p < 0.05). GCF MPO significantly decreased at 3 and 9 months in the SDD group, while it significantly decreased at 6 months in the placebo group (p < 0.05). TRAP and MMP-13 could be detected in none of the samples. Conclusions: The present results indicate that three months of adjunctive usage of SDD to nonsurgical periodontal therapy compared to nonsurgical periodontal therapy alone in periodontitis patients results in further improvement of clinical periodontal parameters and GCF markers of periodontal tissue breakdown over a 12-month period. Beneficial effects of adjunctive SDD therapy is likely to be related to the reduced levels of two major periodontitis-associated MMPs, MMP-8 and -9, and their potential oxidative activator MPO.

Effects on HbA1c in diabetic patients of adjunctive use of systemic antibiotics in nonsurgical periodontal treatment: A systematic review

OBJECTIVE

To assess the effects of adjunctive use of systemic antibiotics in nonsurgical periodontal treatment compared to nonsurgical periodontal treatment alone, on mean glycated hemoglobin (HbA1c) reductions in patients with diabetes.

DATA

Two independent reviewers screened six electronic databases, registers of clinical trials, meeting abstracts and four major dental journals for controlled clinical trials with at least 3-month follow-up.

SOURCES

After duplicates removal, electronic and hand searches yielded 2136 records; 32 full-text articles were independently read by two reviewers. To evaluate the additional effect of antibiotic usage, pooled weighted mean differences and 95% confidence intervals were calculated using fixed and random effects models.

STUDY SELECTION

Twelve studies met the inclusion criteria, nine of which provided data that allowed their inclusion in meta-analyses. The meta-analyses showed no significant effect favouring scaling and root planing (SRP) plus antibiotic for reductions in mean HbA1c (-0.11% [-0.35, 0.13]; 6 studies), and an estimated prediction interval varying from -0.45 to 0.23. There was also no significant effect favouring the adjunctive usage of sub-antimicrobial doxycycline in HbA1c mean reduction (-0.19% [-1.04, 0.67]; 2 studies).

CONCLUSION

Adjunctive use of systemic antibiotic provides no statistically significant benefit in terms of HbA1c improvement in periodontal treatment of patients with diabetes.

CLINICAL SIGNIFICANCE

Adjunctive use of systemic antibiotics associated with nonsurgical periodontal treatment provides no additional benefit in terms of HbA1c of diabetic patients. Clinicians should weigh the trade-off between risks and benefits provided by the use of systemic antibiotics before prescribing them for periodontal disease treatment.

Commentary: Targeting Underlying Biologic Mechanisms in Selecting Adjunctive Therapies to Improve Periodontal Treatment in Smokers: A Commentary

Despite well-established evidence that cigarette smoking is the largest modifiable risk factor for periodontal disease and has many deleterious health effects, treatment of periodontal disease in smokers remains a challenge of periodontal therapy. A recent meta-analysis revealed that adjunctive use of local delivery of antimicrobials, but not systemic antibiotic usage, with non-surgical periodontal therapy resulted in improvement in clinical periodontal parameters. Further evaluation of the current literature reveals that host modulation therapy may also result in clinical benefit in smokers. These findings may be tied to the underlying pathophysiology of periodontal disease progression in smokers and suggest that focused therapies that target known mechanisms of action are critical to the success of proposed treatments.

Repurposing doxycycline for synucleinopathies: remodelling of α-synuclein oligomers towards non-toxic parallel beta-sheet structured species

Synucleinophaties are progressive neurodegenerative disorders with no cure to date. An attractive strategy to tackle this problem is repurposing already tested safe drugs against novel targets. In this way, doxycycline prevents neurodegeneration in Parkinson models by modulating neuroinflammation. However, anti-inflammatory therapy per se is insufficient to account for neuroprotection. Herein we characterise novel targets of doxycycline describing the structural background supporting its effectiveness as a neuroprotector at subantibiotic doses. Our results show that doxycycline reshapes α-synuclein oligomers into off-pathway, high-molecular-weight species that do not evolve into fibrils. Off-pathway species present less hydrophobic surface than on-pathway oligomers and display different β-sheet structural arrangement. These structural changes affect the α-synuclein ability to destabilize biological membranes, cell viability, and formation of additional toxic species. Altogether, these mechanisms could act synergically giving novel targets for repurposing this drug.

Systematic review and meta-analysis on the nonsurgical treatment of chronic periodontitis by means of scaling and root planing with or without adjuncts

BACKGROUND

Conduct a systematic review and meta-analysis on nonsurgical treatment of patients with chronic periodontitis by means of scaling and root planing (SRP) with or without adjuncts.

METHODS

A panel of experts convened by the American Dental Association Council on Scientific Affairs conducted a search of PubMed (MEDLINE) and Embase for randomized controlled trials of SRP with or without the use of adjuncts with clinical attachment level (CAL) outcomes in trials at least 6 months in duration and published in English through July 2014. The authors assessed individual study bias by using the Cochrane Risk of Bias Tool and conducted meta-analyses to obtain the summary effect estimates and their precision and to assess heterogeneity. The authors used funnel plots and Egger tests to assess publication bias when there were more than 10 studies. The authors used a modified version of the US Preventive Services Task Force methods to assess the overall level of certainty in the evidence.

RESULTS

The panel included 72 articles on the effectiveness of SRP with or without the following: systemic antimicrobials, a systemic host modulator (subantimicrobial-dose doxycycline), locally delivered antimicrobials (chlorhexidine chips, doxycycline hyclate gel, and minocycline microspheres), and a variety of nonsurgical lasers (photodynamic therapy with a diode laser, a diode laser, neodymium:yttrium-aluminum-garnet lasers, and erbium lasers).

CONCLUSIONS AND PRACTICAL IMPLICATIONS

With a moderate level of certainty, the panel found approximately a 0.5-millimeter average improvement in CAL with SRP. Combinations of SRP with assorted adjuncts resulted in a range of average CAL improvements between 0.2 and 0.6 mm over SRP alone. The panel judged the following 4 adjunctive therapies as beneficial with a moderate level of certainty: systemic subantimicrobial-dose doxycycline, systemic antimicrobials, chlorhexidine chips, and photodynamic therapy with a diode laser. There was a low level of certainty in the benefits of the other included adjunctive therapies. The panel provides clinical recommendations in the associated clinical practice guideline.

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.

Evaluation of the effects of two different bone resorption inhibitors on osteoclast numbers and activity: An animal study

Background:

The aim of this study was to evaluate the effects of bone resorption inhibitors, doxycycline (DOX) and erythromycin (EM), on osseous wound healing in rat alveolar socket.

Materials and Methods:

In this randomized controlled trial, 45 8–10-week-old male Wistar rats had their maxillary right molar extracted. They were divided into three groups of 15. In Group 1 normal saline, Group 2 DOX, and Group 3 EM were administered at the doses of 5 ml/kg/day, 5 mg/kg/day, and 2 mg/kg/day, respectively, for 7 consecutive days. The rats were sacrificed 7, 14, and 21 days after surgery. Real-time polymerase chain reaction was employed to evaluate the mRNA expression of receptor activator of nuclear factor κB ligand (RANKL) and osteoprotegerin (OPG) and immunohistochemical staining for tartrate-resistant acid phosphatase (TRAP) to determine osteoclasts. The data were analyzed by one-way analysis of variance followed by Tukey's post hoc test using SPSS version 20. Significant level was set at 0.05.

Results:

The results showed that when drug-treated groups compared to control groups, RANKL gene expression significantly decreased, TRAP⁺ cells decreased on day 7. The RANKL/OPG ratios in the first two weeks in the test groups were significantly lower than the control group. There was no significant difference in the studied indices between DOX and EM groups.

Conclusion:

Following administration of DOX and EM, the number of osteoclasts and RANKL/OPG ratio decreased suggesting their anti-osteoclastogenesis activity. These two drugs have no advantage over each other in increasing the bone formation.

Systemic Antibiotics in Periodontal Treatment of Diabetic Patients: A Systematic Review

Aim

To evaluate the effects of systemic antibiotics in combination with scaling and root planing (SRP) on periodontal parameters, tooth loss and oral health-related quality of life in diabetes patients.

Materials and Methods

Two independent reviewers screened for controlled clinical trials with at least 6-month follow-up in six electronic databases, registers of clinical trials, meeting abstracts and four major dental journals. After duplicates removal, electronic and hand searches yielded 1,878 records; 18 full-text articles were independently read by two reviewers. To evaluate the additional effect of antibiotic usage, pooled weighted mean differences and 95% confidence intervals were calculated using a fixed effects model.

Results

Five studies met the inclusion criteria, four of which were included in meta-analyses. The meta-analyses showed a significant effect favouring SRP plus antibiotic for reductions in mean probing depth (PD) (-0.22 mm [-0.34, -0.11]) and mean percentage of bleeding on probing (BoP) (4% [-7, -1]). There was no significant effect for clinical attachment level gain and plaque index reduction. No study reported on tooth loss and oral health-related quality of life.

Conclusion

Adjunctive systemic antibiotic use in diabetic patients provides a small additional benefit in terms of reductions in mean PD and mean percentage of BoP.

Registration

PROSPERO: CRD42013006389.

Matrix metalloproteinases and their tissue inhibitor after reperfused ST-elevation myocardial infarction treated with doxycycline. Insights from the TIPTOP trial

BACKGROUND

The TIPTOP (Early Short-term Doxycycline Therapy In Patients with Acute Myocardial Infarction and Left Ventricular Dysfunction to Prevent The Ominous Progression to Adverse Remodelling) trial demonstrated that a timely, short-term therapy with doxycycline is able to reduce LV dilation, and both infarct size and severity in patients treated with primary percutaneous intervention (pPCI) for a first ST-elevation myocardial infarction (STEMI) and left ventricular (LV) dysfunction. In this secondary, pre-defined analysis of the TIPTOP trial we evaluated the relationship between doxycycline and plasma levels of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs).

METHODS

In 106 of the 110 (96%) patients enrolled in the TIPTOP trial, plasma MMPs and TIMPs were measured at baseline, and at post-STEMI days 1, 7, 30 and 180. To evaluate the remodeling process, 2D-Echo studies were performed at baseline and at 6months. A (99m)Tc-SPECT was performed to evaluate the 6-month infarct size and severity.

RESULTS

Doxycycline therapy was independently related to higher plasma TIMP-2 levels at day 7 (p<0.05). Plasma TIMP-2 levels above the median value at day 7 were correlated with the 6-month smaller infarct size (3% [0%-16%] vs. 12% [0%-30%], p=0.002) and severity (0.55 [0.44-0.64] vs. 0.45 [0.29-0.60], p=0.002), and LV dilation (-1ml/m(2) [from -7ml/m(2) to 9ml/m(2)] vs. 3ml/m(2) [from -2ml/m(2) to 19ml/m(2)], p=0.04), compared to their counterpart.

CONCLUSIONS

In this clinical setting, doxycycline therapy results in higher plasma levels of TIMP-2 which, in turn, inversely correlate with 6month infarct size and severity as well as LV dilation.

Interference of doxycycline pretreatment in a model of abdominal aortic aneurysms

BACKGROUND

Abdominal aortic aneurysm (AAA) is characterized by chronic inflammation and degradation of the extracellular matrix, mediated by matrix metalloproteinases (MMPs). Doxycycline has been reported to control the progression of AAA by regulation of MMP. We hypothesized that doxycycline pretreatment in a rat model of AAA would cause reduction in gelatinolytic activity of MMP-2 and -9 and the inflammatory response in the wall of an aneurysm, consequently decreasing the formation and development of AAAs.

METHODS

Male Wistar rats were divided into the following four groups: aneurysm (A); control (C); aneurysm+doxycycline (A+D) and control+doxycycline (C+D), with 24 animals per group subdivided into n=6 animals at different time points [1, 3, 7, and 15 days postsurgery (dps)]. The (A) and (A+D) groups simultaneously received the injury and extrinsic stenosis of the aortic wall. The (C) and (C+D) groups received sham operation. The treated animals received doxycycline via gavage (30 mg/kg/day) from 48 h before surgery until the end of experiment. At 1, 3, 7, and 15 dps, the animals were euthanized, and the aortas were collected for morphological analyses, immunohistochemistry, and zymography.

RESULTS

The animals from the (A) group developed AAAs. However, the animals treated with doxycycline showed a 85% decrease in AAA development, which was associated with a large reduction in gelatinolytic activity of MMP-2 and -9, and decreased inflammatory response (P<.05).

CONCLUSIONS

These results suggest that pretreatment with doxycycline before surgery inhibited the activity of MMP-2 and -9, as well as the inflammatory response, and may play an important role in the prevention of the development of AAAs.

Effect of Azadirachta indica (Neem) and Aloe vera as compared to subantimicrobial dose doxycycline on matrix metalloproteinases (MMP)-2 and MMP-9: An in-vitro study

Background:

A critical outcome of periodontal diseases is degradation of collagen in the periodontal tissues, by enzymes such as Matrix Metallo-Proteinases (MMPs). Doxycycline is known to down-regulate the activity of MMPs. Azadirachta indica (Neem) and Aloe vera are herbs known to have an anti-inflammatory effect. The present study was designed to evaluate the anti-inflammatory effect of Neem and Aloe vera by way of its inhibitory effect on MMP-2 and MMP-9 activity in cases of chronic periodontitis and compare it with doxcycline.

Materials and Methods:

A total of 30 subjects were enrolled in this study. Gingival tissue samples were obtained from patients diagnosed with the chronic periodontitis. The tissue extracts were treated with the said drug solutions and inhibition of MMP-2 and MMP-9 was analyzed. Enzymatic activity was detected by electrophoresis. The data was subjected to Student's paired t-test.

Results:

The results showed that the activity of MMP-2 and MMP-9 was significantly decreased by the use of doxycycline, Neem and Aloe vera. A 53.5% reduction in the MMP-2 and 52.5% reduction in the MMP-9 activity was seen when samples were subjected to Neem treatment at the concentration of 1500 μg/ml. Tissues treated with Aloe vera in the concentration of 2000 μg/ml showed a 20.09% reduction in the MMP-2 and 20.4% reduction in the MMP-9 activity. Doxycycline in the concentration of 300 μg/ml, showed an 82.1% reduction in the MMP-2 and 82.6% reduction in the MMP-9 activity.

Conclusion:

The present study demonstrated an inhibitory effect of Neem and Aloe vera on MMP-2 and MMP-9, which are involved in the extracellular matrix degradation during periodontitis.

Smoothelin-B is not a target of matrix metalloproteinase (MMP)-2 in the vasculature of endotoxemic rats

Smoothelin-B (SMTL-B) and calponin-1 are important regulators of vascular contraction. SMTL-B contains a calponin-homology domain and is structurally similar to cardiac troponin T. As calponin-1 and troponin T are proteolyzed by intracellular matrix metalloproteinase (MMP)-2 in oxidative stress injury, we hypothesized that SMTL-B is also cleaved by MMP-2 and contributes to lipopolysaccharide (LPS)-induced vascular hypocontractility. Rats received ONO-4817 (an MMP inhibitor) or its vehicle, 2 h prior to being administered lipopolysaccharide (LPS). LPS-induced aorta hypocontractility to potassium chloride or phenylephrine, and reduction of calponin-1 levels, were abolished by ONO-4817 at 6 but not 3 h after LPS. However, the level of SMTL-B was unaltered in LPS aortas and further unaffected by ONO-4817. Despite the importance of SMTL-B in vascular tone, it is not a target of MMP-2 in LPS-induced hypocontractility.

Brimonidine tartrate for the treatment of facial flushing and erythema in rosacea

Rosacea is a chronic inflammatory dermatologic condition that can often be disfiguring with significant negative impact on patients' quality of life. Sanrosa (brimonidine tartate) is a novel therapeutic agent targeting the facial flushing and erythema of rosacea through its α₂ adrenergic receptor agonist activity. The goal of this article is to discuss current treatment options for rosacea and the properties of brimonidine tartate as well as the evidence surrounding its efficacy and safety profile.

Clinical utility of locally-delivered collagen-based biodegradable tetracycline fibers in periodontal therapy: an in vivo study

AIM

The purpose of the present investigation was to evaluate and compare the efficacy of resorbable collagen-based tetracycline fibers (Periodontal Plus AB fibers) given as an adjunct to scaling and root planing, with the clinical effects of scaling and root planning delivered as a monotherapy, in the treatment of chronic periodontitis.

METHODS

A split-mouth design was used to conduct this study. Forty patients with periodontal pockets ranging from ≥ 5 mm to ≤ 7 mm, with minimum of two sites in two non-adjacent quadrants, were selected for the study. The treatment sites in each patient were randomly divided into the control and experimental groups. All of the selected sites were treated with scaling and root planning, and then collagen-based resorbable tetracycline fibers were placed adjunctively in the experimental sites at the same visit. Baseline and follow-up measurements in both treatment groups included plaque index, sulcus bleeding index, probing pocket depth, and relative attachment level.

RESULTS

Although significant clinical benefits were obtained in both treatment groups, the adjunctive antimicrobial use of tetracycline fibers demonstrated better results compared to the control group over the 3-month observational period.

CONCLUSIONS

The delivery of antimicrobial agent tetracycline in a collagen matrix was found to improve the benefits of scaling and root planing by a larger magnitude in patients with moderate-to-deep pockets.

[Doxycycline or how to create new with the old?]

Tetracyclines are broad-spectrum antibiotics that interfere with protein synthesis. They were first widely prescribed by dermatologists in the early 1950s in the treatment of acne. More recently, their biological actions on inflammation, proteolysis, angiogenesis, apoptosis, metal chelation, ionophoresis, and bone metabolism were studied. Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that degrade components of the extracellular matrix (ECM). MMPs have direct or indirect effects on the vascular endothelium and the vascular relaxation/contraction system. The therapeutic effects of tetracyclines and analogues were studied in rosacea, bullous dermatoses, neutrophilic diseases, pyoderma gangrenosum, sarcoidosis, aortic aneurysms, cancer metastasis, periodontitis and autoimmune diseases autoimmune diseases such as rheumatoid arthritis and scleroderma. In addition, downregulation of MMP using doxycycline could be beneficial in reducing vascular dysfunction mediated by MMPs and progressive damage of the vascular wall. We review the nonantibiotic properties of doxycycline and its potential clinical applications.

Protein biomarkers of periodontitis in saliva

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

Emerging therapies in rosacea

Rosacea is a common skin disorder with multiple symptoms. The emergence of research that furthers understanding of pathophysiological mechanisms has created new targets for disease treatment. Specifically, there is a need for new treatments that address the various erythematic symptoms associated with rosacea. Systemic and topical therapies have both yielded positive results in treating rosacea with various medications. Subantimicrobial-dose doxycycline is one such promising treatment. Development of novel products in the near future should help achieve more satisfactory outcomes for patients.

Early short-term doxycycline therapy in patients with acute myocardial infarction and left ventricular dysfunction to prevent the ominous progression to adverse remodelling: the TIPTOP trial

AIMS

Experimental studies suggest that doxycycline attenuates post-infarction remodelling and exerts protective effects on myocardial ischaemia/reperfusion injury. However, the effects of the drug in the clinical setting are unknown. The aim of this study was to examine the effect of doxycycline on left ventricular (LV) remodelling in patients with acute ST-segment elevation myocardial infarction (STEMI) and LV dysfunction.

METHODS AND RESULTS

Open-label, randomized, phase II trial. Immediately after primary percutaneous coronary intervention, patients with STEMI and LV ejection fraction < 40% were randomly assigned to doxycycline (100 mg b.i.d. for 7 days) in addition to standard therapy, or to standard care. The echo LV end-diastolic volumes index (LVEDVi) was determined at baseline and 6 months. (99m)Tc-Sestamibi-single-photon emission computed tomography infarct size and severity were assessed at 6 months. We calculated a sample size of 110 patients, assuming that doxycycline may reduce the increase in the LVEDVi from baseline to 6 months > 50% compared with the standard therapy (statistical power > 80% with a type I error = 0.05). The 6-month changes in %LVEDVi were significant smaller in the doxycycline group than in the control group [0.4% (IQR: -16.0 to 14.2%) vs.13.4% (IQR: -7.9 to 29.3%); P = 0.012], as well as infarct size [5.5% (IQR: 0 to 18.8%) vs. 10.4% (IQR: 0.3 to 29.9%) P = 0.052], and infarct severity [0.53 (IQR: 0.43-0.62) vs. 0.44 (IQR: 0.29-0.60), P = 0.014], respectively.

CONCLUSION

In patients with acute STEMI and LV dysfunction, doxycycline reduces the adverse LV remodelling for comparable definite myocardial infarct size (NCT00469261).

Effect of low-dose doxycycline on serum oxidative status, gingival antioxidant levels, and alveolar bone loss in experimental periodontitis in rats

BACKGROUND

Subantibiotic doses of doxycycline (low-dose doxycycline [LDD]) have been widely used in periodontal treatment for enzymatic inhibition and related anti-inflammatory properties. The aim of the present study is to verify the possible effects of LDD on oxidative stress in relation to periodontal attachment loss associated with ligature-induced experimental periodontal disease in rats.

METHODS

Thirty female Wistar albino rats were divided into three study groups as follows: 1) control (C) rats; 2) rats with experimental periodontitis (PED); and 3) rats with PED that were treated with doxycycline (PED + LDD). PED was induced by placing ligatures around the cervix of the maxillary second molars for 21 days. The PED + LDD group was treated orally with doxycycline (6 mg/kg) for 21 days after the ligature was placed. After 21 days, the rats were euthanized, and samples of the right maxilla were defleshed and used for histologic and morphometric analyses. The gingival tissue of the left maxilla was used for the analysis of lipid peroxidation (malondialdehyde [MDA]) and antioxidant enzymes (catalase, glutathione peroxidase, and superoxide dismutase). Levels of serum total antioxidant status (TAS)/total oxidant status (TOS) and oxidative stress index (OSI) were also analyzed.

RESULTS

Alveolar bone loss was significantly higher in the PED group compared with the PED + LDD and C groups (P <0.05). Doxycycline exhibited the most prominent inhibition on gingival tissue levels of MDA and antioxidant enzymes (P <0.05). Doxycycline also significantly reduced TOS and OSI levels (P <0.05) but increased the TAS level.

CONCLUSION

Doxycycline helps to prevent periodontal tissue breakdown by inhibiting local and systemic oxidative stress.

Neutrophil activity in chronic venous leg ulcers--a target for therapy?

Chronic venous leg ulcers (CVLUs) affect approximately 600,000 people annually in the United States and accrue yearly treatment costs of US $2.5-5 billion. As the population ages, demands on health care resources for CVLU treatments are predicted to drastically increase because the incidence of CVLUs is highest in those ≥65 years of age. Furthermore, regardless of current standards of care, healing complications and high recurrence rates prevail. Thus, it is critical that factors leading to or exacerbating CVLUs be discerned and more effective, adjuvant, evidence-based treatment strategies be utilized. Previous studies have suggested that CVLUs' pathogenesis is related to the prolonged presence of high numbers of activated neutrophils secreting proteases in the wound bed that destroy growth factors, receptors, and the extracellular matrix that are essential for healing. These events are believed to contribute to a chronically inflamed wound that fails to heal. Therefore, the purpose of this project was to review studies from the past 15 years (1996-2011) that characterized neutrophil activity in the microenvironment of human CVLUs for new evidence that could explicate the proposed relationship between excessive, sustained neutrophil activity and CVLUs. We also appraised the strength of evidence for current and potential therapeutics that target excessive neutrophil activity.

Rheumatoid arthritis in the elderly and its relationship with periodontitis: a review

Periodontitis and rheumatoid arthritis are chronic inflammatory diseases commonly seen in the elderly. It has been proposed that the two conditions are interrelated and influence the severity of each other. Recently, the role of Porphyromonas gingivalis, a periodontopathogen, has been explained in the pathogenesis and progression of rheumatoid arthritis. It can be inferred from the present review that the two conditions share a common pathobiology, genetics and environmental risk factors. Furthermore, a thorough understanding of the aforementioned mechanisms might enable the development of conjoint treatment modalities beneficial in treating the geriatric population afflicted by both the disorders.

Evaluation of the effect of allograft with doxycycline versus the allograft alone in the treatment of infrabony defects: A controlled clinical and radiographical study

BACKGROUND

Successful prevention and treatment of periodontal disease are contingent on effective control of periodontopathic microbiota based on the premise of periodontal disease being infectious disorders. An anti-microbial agent, i.e., doxycycline has been incorporated into the allograft to control infection and facilitate healing during and after periodontal therapy.

MATERIALS AND METHODS

Using a split-mouth design, 15 patients showing clinical evidence of almost identical bilateral infrabony defects requiring bone grafting procedures were randomly selected. In each patient, infrabony defects on one side were designated as Group A (control group) and infrabony defects of the contralateral side of the same arch were designated as Group B (test group). Clinical assessment of probing pocket depth and attachment level and radiographic evaluation of the defect depth was done pre-operatively and at 12-week and 24-week post-operatively. The relative efficacy of the two treatment modalities was evaluated using paired Student's t-test and the comparative evaluation between the two groups over the 3 time intervals was done using independent Student's t-test.

RESULTS

Both the groups exhibited a highly significant reduction in probing depth and gain in clinical attachment level (CAL) and a linear bone fill at the end of 12 and 24 weeks. Comparative evaluation showed a statistically significant gain in bone fill in Group B as compared to Group A, whereas a non-significant reduction in probing depth and gain in CALs between the two groups at the end of 24 weeks (whereas mean reduction in probing depth and gain in CAL were also greater in Group B but the difference was statistically non-significant).

CONCLUSION

The increase in linear bone fill in Group B signifies the role of doxycycline in augmenting regenerative potential of allograft by combating residual infection and through host modulation.

Dentin adhesion and MMPs: a comprehensive review

This review examines the fundamental processes responsible for the aging mechanisms involved in the degradation of resin-bonded interfaces, as well as some potential approaches to prevent and counteract this degradation. Current research in several research centers aims at increasing the resin-dentin bond durability. The hydrophilic and acidic characteristics of current dentin adhesives have made hybrid layers highly prone to water sorption. This, in turn, causes polymer degradation and results in decreased resin-dentin bond strength over time. These unstable polymers inside the hybrid layer may result in denuded collagen fibers, which become vulnerable to mechanical and hydrolytical fatigue, as well as degradation by host-derived proteases with collagenolytic activity. These enzymes, such as matrix metalloproteinases and cysteine cathepsins, have a crucial role in the degradation of type I collagen, the organic component of the hybrid layer. This review will also describe several methods that have been recently advocated to silent the activity of these endogenous proteases.

Antimicrobial or subantimicrobial antibiotic therapy as an adjunct to the nonsurgical periodontal treatment: a meta-analysis

The use of antibiotics in nonsurgical periodontal treatment is indicated in cases in which scaling and root planing present important limitations. However, their use is controversial due to the secondary effects associated with them and the disagreements regarding their prescription. The aim of this study is to determine the effectiveness of systemic antibiotics in the management of aggressive and chronic periodontitis. The study was based on a search of randomized, controlled clinical trials. Common data were concentrated and evaluated by means of an analysis of variance (ANOVA), and a meta-analysis of the results was performed. The meta-analysis (P < 0.05, 95% confidence interval, post hoc Bonferroni) determined that the supplementation of nonsurgical periodontal therapy with a systemic antibiotic treatment—amoxicillin with clavulanic acid and metronidazole or subantimicrobial dose doxycycline—provides statistically significant results in patients with aggressive or chronic periodontitis under periodontal treatment, whilst increasing the clinical attachment level of the gingiva and reducing periodontal probing depth.

Host modulation by therapeutic agents

Periodontal disease susceptible group present advanced periodontal breakdown even though they achieve a high standard of oral hygiene. Various destructive enzymes and inflammatory mediators are involved in destruction. These are elevated in case of periodontal destruction. Host modulation aims at bringing these enzymes and mediators to normal level. Doxycycline, nonsteroidal anti-inflammatory drugs (NSAIDs), bisphosphonates, nitrous oxide (NO) synthase inhibitors, recombinant human interleukin-11 (rhIL-11), omega-3 fatty acid, mouse anti-human interleukin-6 receptor antibody (MRA), mitogen-activated protein kinase (MAPK) inhibitors, nuclear factor-kappa B (NF-kb) inhibitors, osteoprotegerin, and tumor necrosis factor antagonist (TNF-α) are some of the therapeutic agents that have host modulation properties.

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.

Increasing extracellular matrix collagen level and MMP activity induces cyst development in polycystic kidney disease

Background

Polycystic Kidney Disease (PKD) kidneys exhibit increased extracellular matrix (ECM) collagen expression and metalloproteinases (MMPs) activity. We investigated the role of these increases on cystic disease progression in PKD kidneys.

Methods

We examined the role of type I collagen (collagen I) and membrane bound type 1 MMP (MT1-MMP) on cyst development using both in vitro 3 dimensional (3D) collagen gel culture and in vivo PCK rat model of PKD.

Results

We found that collagen concentration is critical in controlling the morphogenesis of MDCK cells cultured in 3D gels. MDCK cells did not form 3D structures at collagen I concentrations lower than 1 mg/ml but began forming tubules when the concentration reaches 1 mg/ml. Significantly, these cells began to form cyst when collagen I concentration reached to 1.2 mg/ml, and the ratios of cyst to tubule structures increased as the collagen I concentration increased. These cells exclusively formed cyst structures at a collagen I concentration of 1.8 mg/ml or higher. Overexpression of MT1-MMP in MDCK cells significantly induced cyst growth in 3D collagen gel culture. Conversely, inhibition of MMPs activity with doxycycline, a FDA approved pan-MMPs inhibitor, dramatically slowed cyst growth. More importantly, the treatment of PCK rats with doxycycline significantly decreased renal tubule cell proliferation and markedly inhibited the cystic disease progression.

Conclusions

Our data suggest that increased collagen expression and MMP activity in PKD kidneys may induce cyst formation and expansion. Our findings also suggest that MMPs may serve as a therapeutic target for the treatment of human PKD.

Efficacy of short-term adjunctive subantimicrobial dose doxycycline in diabetic patients--randomized study

OBJECTIVE

To investigate the effectiveness of short-term adjunctive subantimicrobial dose doxycycline (SDD) treatment in patients with diabetes mellitus type 2 and chronic periodontitis (CP).

METHODS

Thirty-four patients with CP and type 2 diabetes mellitus were included in the placebo-controlled, double-blind study. After scaling and root planing (SRP), patients were randomly assigned to two groups, receiving either SDD or placebo bid for 3 months. The probing depth (PD), clinical attachment level (CAL), bleeding on probing (BOP), approximal plaque index, glycated hemoglobin (HbA1c) level were recorded and gingival crevicular fluid (GCF) samples were collected at baseline and after 3-month therapy for the estimation of matrix metalloproteinase-8 levels.

RESULTS

Clinical attachment level, PD, and BOP improved significantly in both groups after therapy (P < 0.05). The statistically significant difference between the two groups after the therapy was observed only in PD in tooth sites with initial PD ≥ 4 mm (SRP + placebo: 3.41 ± 0.6 mm vs SRP + SDD: 2.92 ± 0.5 mm, P < 0.05). GCF matrix metalloproteinase-8 levels were significantly reduced only in SRP + SDD group (P < 0.01). There were no changes in HbA1c levels after therapy.

CONCLUSION

The short-term administration of SDD gives significant benefit at tooth sites with moderate disease (PD ≥ 4 mm) when compared to SRP alone in patients with diabetes and CP.

Matrix metalloproteinase inhibitor properties of tetracyclines: therapeutic potential in cardiovascular diseases

Matrix metalloproteinases (MMPs) are a family of proteases best known for their capacity to proteolyse several proteins of the extracellular matrix. Their increased activity contributes to the pathogenesis of several cardiovascular diseases. MMP-2 in particular is now considered to be also an important intracellular protease which has the ability to proteolyse specific intracellular proteins in cardiac muscle cells and thus reduce contractile function. Accordingly, inhibition of MMPs is a growing therapeutic aim in the treatment or prevention of various cardiovascular diseases. Tetracyclines, especially doxycycline, have been frequently used as important MMP inhibitors since they inhibit MMP activity independently of their antimicrobial properties. In this review we will focus on the intracellular actions of MMPs in some cardiovascular diseases including ischemia and reperfusion (I/R) injury, inflammatory heart diseases and septic shock; and explain how tetracyclines, as MMP inhibitors, have therapeutic actions to treat such diseases. We will also briefly discuss how MMPs can be intracellularly regulated and activated by oxidative stress, thus cleaving several important proteins inside cells. In addition to their potential therapeutic effects, MMP inhibitors may also be useful tools to understand the biological consequences of MMP activity and its respective extra- and intracellular effects.

Long-term efficacy of subantimicrobial-dose doxycycline as an adjunctive treatment to scaling and root planing: a systematic review and meta-analysis

BACKGROUND

Subantimicrobial-dose doxycycline (SDD) is widely used as an adjunctive treatment to scaling and root planing (SRP), but its long-term effectiveness remains controversial. The purpose of this systematic review was to assess the actual evidence of the effectiveness of SRP + SDD compared to SRP + placebo in the treatment of chronic periodontitis.

METHODS

A literature search of electronic databases was performed for articles published through November 1, 2010. Several dental journals were screened during the manual search, and authors were contacted for missing information. The systematic review and meta-analysis were conducted according to the Quality of Reporting of Meta-Analyses statement and recommendations of the Cochrane Collaboration. The methodologic quality of the studies was determined via a Consolidated Standards of Reporting Trials-based assessment. Clinical attachment levels, probing depths, plaque and gingival indices, and gingival crevicular fluid levels were compared between baseline and the end of follow-up. Data were extracted and pooled using a random-effect model. The weighted mean difference was reported with the 95% confidence interval. Heterogeneity was assessed using the χ(2)-based Q-statistic method and I(2) measurement. P <0.05 was considered statistically significant.

RESULTS

After applying inclusion and exclusion criteria, three randomized placebo-controlled clinical trials were entered into the meta-analysis. These studies had similar treatment designs, SDD dosage regimens (20 mg twice daily for 3 months), and post-treatment follow-up lengths (9 months). Significant differences were observed for all investigated clinical parameters in favor of the SRP + SDD group.

CONCLUSION

The meta-analysis results seemed to support the long-term effectiveness of adjunctive SDD therapy; however, future studies are needed to confirm these findings.

Clinical studies on the management of periodontal diseases utilizing subantimicrobial dose doxycycline (SDD)

Periodontitis, the most common chronic inflammatory condition known to mankind, is a disease that results in the destruction of tooth supporting tissues. Periodontitis is initiated by a bacterial biofilm on the tooth surface below the gingival margin. Until fairly recently it was assumed that the bacteria were the primary cause of tissue destruction, however, a large body of research has revealed that it is the patient's immune response that is actually responsible for the majority of the breakdown of tooth supporting tissues. Contemporary thinking suggests that successful, long term management of chronic periodontitis may combine both local mechanical and antimicrobial strategies to reduce the microbial bio-burden along with modulation of the host, patient's excessive, immuno-inflammatory response to the bacterial exposure known as host modulatory therapy (HMT). Based on extensive literature documenting the enzymatic inhibition and related anti-inflammatory properties of the tetracyclines, a new drug was developed as a host modulatory agent and approved by the United States Food and Drug Administration (FDA) for use as an adjunct to conventional scaling and root planing for the treatment of chronic periodontitis. A subantimicrobial dose of doxycycline (SDD) at 20 mg (Periostat(®)) has been found to be a safe and effective adjunct when taken twice daily for at least 3 months and up to 24 months in randomized placebo controlled clinical trials. Periostat(®) is currently the only FDA approved inhibitor of the matrix metalloproteinases implicated in the plaque-induced pathologic degradation of connective tissue collagen of the periodontal supporting structures. This review paper begins with a brief description of the disease process known as periodontitis followed by an extensive review of the Phase I-IV clinical trial data that established the safety and efficacy of sub-antimicrobial dose doxycycline (SDD) as an adjunct to scaling and root planing for the treatment of periodontitis.

Effects of scaling and root planing and subantimicrobial dose doxycycline on gingival crevicular fluid levels of matrix metalloproteinase-8, -13 and serum levels of HsCRP in patients with chronic periodontitis

BACKGROUND

This study evaluates the efficacy of subantimicrobial dose doxycycline (SDD) in conjunction with scaling and root planing (SRP) on gingival crevicular fluid (GCF) levels of matrix metalloproteinase (MMP)-8 and -13 and on serum levels of high-sensitivity C-reactive protein (HsCRP) in patients with chronic periodontitis (CP).

METHODS

A total of 41 patients with CP and 17 healthy individuals were included in this randomized controlled trial. CP patients were randomly distributed into two groups. Study groups were established as Group I with SRP+placebo, Group II with SRP+SDD, and Group III as control. All CP patients received two regimens of SRP and Group II patients also received SDD for 6 weeks. At baseline and 6 weeks, GCF and blood were collected and clinical indices were recorded. The HsCRP level was assayed in the plasma on a nephelometer. The GCF levels of MMPs were assayed by an enzyme-linked immunosorbent assay.

RESULTS

Statistically significant differences in plaque index, gingival index (GI), probing depth (PD), GCF volumes, GCF MMP levels, and serum levels of HsCRP between pre-treatment and post-treatment were noted in both groups. Between groups there was a statistically significant decrease in PD, GI, and GCF levels of MMP-8 favoring the group receiving SDD adjunctive to SRP (P <0.05).

CONCLUSION

In this study, greater improvement was detected for PD, GI, and GCF levels of MMP-8 when using SRP+SDD compared to SRP+placebo.

Clinical and biochemical efficacy of minocycline in nonsurgical periodontal therapy: a randomized controlled pilot study

The present study evaluated the effects of systemic minocycline on clinical and biochemical parameters of chronic periodontitis, which is a common inflammatory disorder of the periodontium initiated by the presence of bacteria in the gingival sulcus. Besides nonsurgical periodontal therapy, 20 individuals received minocycline systemically while another 20 subjects received placebo capsules for 2 weeks. Plaque index (PI), sulcus bleeding index (SBI), probing depth (PD), and relative attachment level (RAL) were measured and gingival crevicular fluid (GCF) samples were obtained at baseline and first, third, and sixth months. Matrix metalloproteinase-8 (MMP-8) and prostaglandin E₂ (PGE₂) levels were analyzed by enzyme immunoassay method. Significant improvements in all parameters in both groups were recorded. In the minocycline group, changes in PI and SBI were significantly greater only at first month, whereas reductions in PD, RAL, MMP-8, and PGE₂ levels were greater at all times. MMP-8 and PGE₂ exhibited positive correlations with SBI, PD, and each other. Minocycline demonstrated clinical benefit for periodontal therapy and provided further improvements on inflammatory mediators promising a host-modulating capacity.