Minocycline reduces gingival collagenolytic activity during diabetes. Preliminary observations and a proposed new mechanism of action

Febrile ulceronecrotic mucha habermann disease: case report of a dark-skinned patient

A male dark-skinned patient, 33 years old, complaining of a 1-month history of skin lesions in the abdominal region and high fever was admitted to the clinical ward. There were ulcerated and coalescent skin lesions all over the body but sparing the palmar region. The culture of material obtained from the penile lesions was positive for Staphylococcus aureus. He was treated with oxacillin and prednisone. The patient persisted with high fever and skin lesions. After histopathological diagnosis of Mucha Habermann's disease, treatment was started with tetracycline with rapid improvement of the lesions. He was reexamined by the dermatologic service with no recurrences during the 12 months of follow-up. At this time, there was a great number of keloid scars from the skin lesions.

What is behind the non-antibiotic properties of minocycline?

Minocycline is a second-generation, semi-synthetic tetracycline that has been in use in therapy for over 30 years for its antibiotic properties against both Gram-positive and Gram-negative bacteria. It displays antibiotic activity due to its ability to bind to the 30S ribosomal subunit of bacteria and thus inhibit protein synthesis. More recently, it has been described to exert a variety of biological actions beyond its antimicrobial activity, including anti-inflammatory and anti-apoptotic activities, inhibition of proteolysis, as well as suppression of angiogenesis and tumor metastasis, which have been confirmed in different experimental models of non-infectious diseases. There are also many studies that have focused on the mechanisms involved in these non-antibiotic properties of minocycline, including anti-oxidant activity, inhibition of several enzyme activities, inhibition of apoptosis and regulation of immune cell activation and proliferation. This review summarizes the current findings in this topic, mainly focusing on the mechanisms underlying the immunomodulatory and anti-inflammatory activities of minocycline.

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.

Effect of local drug delivery in chronic periodontitis patients: A meta-analysis

Periodontal diseases are multi-factorial in etiology, and bacteria are one among these etiologic agents. Thus, an essential component of therapy is to eliminate or control these pathogens. This has been traditionally accomplished through mechanical means (scaling and root planing (SRP)), which is time-consuming, difficult, and, sometimes, ineffective. From about the past 30 years, locally delivered, anti-infective pharmacological agents, most recently employing sustained-release vehicles, have been introduced to achieve this goal. This systematic review is an effort to determine the efficacy of the currently available anti-infective agents, with and without concurrent SRP, in controlling chronic periodontitis. Four studies were included, which were all randomized controlled trials, incorporating a total patient population of 80, with 97 control sites and 111 test sites. A meta-analysis completed on these four studies including SRP and local sustained-release agents compared with SRP alone indicated significant adjunctive probing depth (PD) reduction for 10% Doxycycline hycylate (ATRIDOX), minocycline hydrochloride (ARESTIN), tetracycline hydrochloride (PERIODONTAL PLUS AB), and chlorhexidine gluconate (PERIOCHIP). Essentially, all studies reported substantial reductions in gingival inflammation, plaque scores, and bleeding indices, which were similar in both the control and the experimental groups. Use of antimicrobial sustained-release systems as an adjunct to SRP does not result in significant patient-centered adverse events. Local drug delivery combined with SRP appears to provide additional benefits in PD reduction compared with SRP alone.

Proof of Concept: Matrix metalloproteinase inhibitor decreases inflammation and improves muscle insulin sensitivity in people with type 2 diabetes

Background

Obesity is a state of subclinical inflammation resulting in loss of function of insulin receptors and decreased insulin sensitivity. Inhibition of the inflammatory enzymes, matrix metalloproteinases (MMPs), for 6 months in rodent models restores insulin receptor function and insulin sensitivity.

Methods

This 12-week double-blind, randomized, placebo (PL)-controlled proof-of-concept study was performed to determine if the MMP inhibitor (MMPI), doxycycline, decreased global markers of inflammation and enhanced muscle insulin sensitivity in obese people with type 2 diabetes (DM2). The study included non-DM2 controls (n = 15), and DM2 subjects randomized to PL (n = 13) or doxycycline 100 mg twice daily (MMPI; n = 11). All participants were evaluated on Day 1; MMPI and PL groups were also evaluated after 84 days of treatment.

Results

There was a significant decrease in inflammatory markers C-reactive protein (P < 0.05) and myeloperoxidase (P = 0.01) in the MMPI but not PL group. The MMPI also significantly increased skeletal muscle activated/total insulin signaling mediators: 3’phosphoinositide kinase-1 (PDK1) (p < 0.03), protein kinase B (PKB/Akt) (p < 0.004), and glycogen synthase kinase 3ß (GSK3ß) (p < 0.03).

Conclusions

This study demonstrated short term treatment of people with diabetes with an MMPI resulted in decreased inflammation and improved insulin sensitivity. Larger, longer studies are warranted to determine if doxycycline can improve glucose control in people with diabetes.

Trial Registration

Clinicaltrials.gov NCT01375491

Chemically modified tetracyclines: Novel therapeutic agents in the management of chronic periodontitis

Chronic periodontitis is a complex infection initiated by gram-negative bacteria which destroy the supporting structures of the tooth. Recently, it has been recognized that it is the host response to bacterial infection which causes greater destruction of the connective tissue elements, periodontal ligament and alveolar bone in periodontitis. This has led to the development of various host modulating approaches to target cells and their destructive mediators involved in tissue degradation. Chemically modified tetracyclines (CMTs) are derivatives of tetracycline group of drugs which lack antimicrobial action but have potent host modulating affects. They inhibit pathologically elevated matrix metal loproteinases, pro-inflammtory cytokines and other destructive mediators. Bone resorption is also suppressed due to their combined anti-proteinase and apoptotic affects on osteoblasts and osteoclasts, respectively. Development of resistant bacteria and gastrointestinal toxicity seen with parent tetracyclines is not produced by CMTs. Hence, CMTs are viewed as potential therapeutic agents in the management of chronic diseases like periodontitis that involve destruction of connective tissue and bone.

Classification Framework and Chemical Biology of Tetracycline-Structure-Based Drugs

By studying the literature about tetracyclines (TCs), it becomes clearly evident that TCs are very dynamic molecules. In some cases, their structure-activity-relationship (SAR) are well known, especially against bacteria, while against other targets, they are virtually unknown. In other diverse fields of research-such as neurology, oncology and virology-the utility and activity of the tetracyclines are being discovered and are also emerging as new technological fronts. The first aim of this paper is to classify the compounds already used in therapy and prepare the schematic structure that includes the next generation of TCs. The second aim of this work is to introduce a new framework for the classification of old and new TCs, using a medicinal chemistry approach to the structure of those drugs. A fully documented Structure-Activity-Relationship (SAR) is presented with the analysis data of antibacterial and nonantibacterial (antifungal, antiviral and anticancer) tetracyclines. The lipophilicity and the conformational interchangeability of the functional groups are employed to develop the rules for TC biological activity.

The history of the tetracyclines

The history of the tetracyclines involves the collective contributions of thousands of dedicated researchers, scientists, clinicians, and business executives over the course of more than 60 years. Discovered as natural products from actinomycetes soil bacteria, the tetracyclines were first reported in the scientific literature in 1948. They were noted for their broad spectrum antibacterial activity and were commercialized with clinical success beginning in the late 1940s to the early 1950s. The second-generation semisynthetic analogs and more recent third-generation compounds show the continued evolution of the tetracycline scaffold toward derivatives with increased potency as well as efficacy against tetracycline-resistant bacteria, with improved pharmacokinetic and chemical properties. Their biologic activity against a wide spectrum of microbial pathogens and their uses in mammalian models of inflammation, neurodegeneration, and other biological systems indicate that the tetracyclines will continue to be successful therapeutics in infectious diseases and as potential therapeutics against inflammation-based mammalian cell diseases.

Cryotherapy and topical minocycline as adjunctive measures to control pain after third molar surgery: an exploratory study

PURPOSE

To assess the impact of cryotherapy or topical minocycline on patients' perceptions of recovery from pain after third molar surgery in an exploratory comparative-effectiveness study.

PATIENTS AND METHODS

Subjects aged at least 14 years who were having all 4 third molars removed were enrolled in 3 separate institutional review board-approved studies. Study groups included subjects treated with a passively applied cold wrap for 24 hours postoperatively, subjects treated with topical minocycline during surgery, and subjects enrolled in a nonconcurrent comparison group who had received neither topical minocycline nor directed cryotherapy. Third molar surgery was performed in all cases by trained surgeons using the same protocol. An exact Kruskal-Wallis test was used to compare the distributions of the worst and average pain scores and a Fisher exact test to compare verbal responses from Gracely pain scales among the 3 groups for postsurgical days (PSDs) 1 to 3.

RESULTS

This study comprised 51 cryotherapy subjects (2005-2009), 63 minocycline subjects (2003-2004), and 92 comparison-group subjects (2002-2006) who were treated at academic centers and in community practices across the United States (N = 206). Demographic descriptors were similar among all groups. For PSDs 1 through 3 (unadjusted), the highest scores for worst pain (6-7 [out of 7] on Likert-type scale) were reported less frequently in each of the study groups than in subjects in the comparison group, although the numbers of subjects reporting the highest scores were few. The distribution of pain outcomes was significantly different among the 3 groups for worst pain and affective words on PSD 1 (P = .04 for both). However, the small number of subjects who reported the highest pain scores precluded adequate multivariate statistical analyses for all outcomes on PSD 1 to 3.

CONCLUSIONS

Data from this exploratory study suggest that adjunctive therapy to decrease postoperative pain-cryotherapy or topical minocycline-might be effective at moderating the patient's highest pain levels after third molar surgery. The topic should be studied further in a multicenter, prospective, randomized trial.

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.

Doxycycline hydrogels as a potential therapy for ocular vesicant injury

PURPOSE

The goals of this study were (1) to compare the injury at the basement membrane zone (BMZ) of rabbit corneal organ cultures exposed to half mustard (2 chloroethyl ethyl sulfide, CEES) and nitrogen mustard with that of in vivo rabbit eyes exposed to sulfur mustard (SM); (2) to test the efficacy of 4 tetracycline derivatives in attenuating vesicant-induced BMZ disruption in the 24-h period postexposure; and (3) to use the most effective tetracycline derivative to compare the improvement of injury when the drug is delivered as drops or hydrogels to eyes exposed in vivo to SM.

METHODS

Histological analysis of hematoxylin and eosin–stained sections was performed; the ultrastructure of the corneal BMZ was evaluated by transmission electron microscopy; matrix metalloproteinase-9 was assessed by immunofluorescence; doxycycline as drops or a hydrogel was applied daily for 28 days to eyes exposed in vivo to SM. Corneal edema was assessed by pachymetry and the extent of neovascularization was graded by length of longest vessel in each quadrant.

RESULTS

Injury to the BMZ was highly similar with all vesicants, but varied in degree of severity. The effectiveness of the 4 drugs in retaining BMZ integrity did not correlate with their ability to attenuate matrix metalloproteinase-9 expression at the epithelial–stromal border. Doxycycline was most effective on organ cultures; therefore, it was applied as drops or a hydrogel to rabbit corneas exposed in vivo to SM. Eyes were examined at 1, 3, 7, and 28 days after exposure. At 7 and 28 days after SM exposure, eyes treated with doxycycline were greatly improved over those that received no therapy. Corneal thickness decreased somewhat faster using doxycycline drops, whereas the hydrogel formulation decreased the incidence of neovascularization.

CONCLUSIONS

Corneal cultures exposed to 2-chloroethyl ethyl sulfide and nitrogen mustard were effective models to simulate in vivo SM exposures. Doxycycline as drops and hydrogels ameliorated vesicant injury. With in vivo exposed animals, the drops reduced edema faster than the hydrogels, but use of the hydrogels significantly reduced neovascularization. The data provide proof of principle that a hydrogel formulation of doxycycline as a daily therapy for ocular vesicant injury should be further investigated.

Chemically modified non-antimicrobial tetracyclines are multifunctional drugs against advanced cancers

Metastatic cancers account for more than 90% of cancer mortality. The metastasis of all cancers is critically mediated by enzymes that degrade extracellular matrix. Aggressive tumors are characterized by an imbalance between enzymes that degrade ECM and endogenous inhibitors of the enzymes. Matrix metalloproteinases (MMPs) make up the majority of ECM degrading enzymes implicated in cancer metastasis. The potent MMP inhibitory activities of tetracyclines, especially their chemically modified analogs, combined with their relatively well tolerated pharmacological profile, led several researchers to investigate their anticancer potential in a variety of cancers, including melanoma, lung, breast and prostate cancers. Chemically modified non-antibiotic tetracyclines (CMTs or COL) were tested using tumors of prostate, breast and melanomas. Some of these CMTs, notably, CMT-3 and CMT-308 significantly inhibited not only invasive potential and MMP activity, but also inhibited cell proliferation by inducing cell cycle arrest and apoptosis. CMT-3 and CMT-308 were significantly more potent than doxycycline or minocycline in inhibiting tumor cell-derived MMPs and inducing apoptosis in vitro and in vivo. CMT-3 (COL-3) showed potent inhibition of tumor growth in xenografts and in bone metastatic models of prostate cancer. Similar results were also reported in melanoma and breast cancer models. The mechanism by which CMTs kill tumor cells is via generation of hydroxyl free radicals ([OH](-)) which permeate and depolarize mitochondria, which in turn activates caspase mediated apoptosis. Analysis of tumor tissues from CMT-3 treated rats demonstrated reduction in angiogenesis and increase in apoptosis; both emerged as mechanisms of CMT action. These observations led to testing the efficacy of CMT-3 in human clinical trials against several types of cancer with significant outcomes, which are described in the next chapter of this issue.

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.

Introduction and background

The rationale for this issue, dedicated to the non-antimicrobial activities of tetracyclines (TCs) as matrix metalloproteinase (and cytokine) - inhibitors, and clinical applications of these properties, is addressed in this introduction. From a historical perspective, the author describes two "breakthrough" experiments that opened this field: (1) the discovery of animal collagenase, the first of a series of matrix metalloproteinases (MMPs) which are now known to be essential mediators of collagen-and connective tissue-destruction including bone loss during various diseases; and (2) the discovery by the author and his team of the unexpected ability of TCs to inhibit these MMPs, and by mechanisms unrelated to the antibiotic activity of these drugs. This led to the development of (i) non-antimicrobial formulations of TCs, ie., sub-antimicrobial-dose doxycycline which resulted in two approved drugs, one for the treatment of periodontal disease, the other for a chronic inflammatory skin disease, and (ii) non-antimicrobial compositions of TCs, ie., the chemically-modified TCs or CMTs or COLs--one of which has shown evidence of efficacy as an anti-angiogenesis agent in human clinical trials on a type of cancer. The development of the CMTs also resulted in the identification of the active site of the TC molecule as an MMP-inhibitor, the calcium and zinc binding site at carbon-11 and 12. And finally, the recently recognized importance of not excessively inhibiting the MMPs because basal levels are needed for various physiologic functions, and the therapeutic potential of TCs as inhibitors of intracellular not just extracellular MMP activity, are both introduced.

Tetracycline compounds with non-antimicrobial organ protective properties: possible mechanisms of action

Tetracyclines were developed as a result of the screening of soil samples for antibiotics. The first^t of these compounds, chlortetracycline, was introduced in 1947. Tetracyclines were found to be highly effective against various pathogens including rickettsiae, as well as both gram-positive and gram-negative bacteria, thus becoming the first class of broad-spectrum antibiotics. Many other interesting properties, unrelated to their antibiotic activity, have been identified for tetracyclines which have led to widely divergent experimental and clinical uses. For example, tetracyclines are also an effective anti-malarial drug. Minocycline, which can readily cross cell membranes, is known to be a potent anti-apoptotic agent. Another tetracycline, doxycycline is known to exert anti-protease activities. Doxycycline can inhibit matrix metalloproteinases which contribute to tissue destruction activities in diseases such as periodontitis. A large body of literature has provided additional evidence for the “beneficial” actions of tetracyclines, including their ability to act as reactive oxygen species scavengers and anti-inflammatory agents. This review provides a summary of tetracycline's multiple mechanisms of action as a means to understand their beneficial effects.

Non-destructive label-free monitoring of collagen gel remodeling using optical coherence tomography

Matrix remodeling plays a fundamental role in physiological and pathological processes, as well as in tissue engineering applications. In this paper, optical coherence tomography (OCT), a non-destructive optical imaging technology, was used to image collagen gel remodeling by smooth muscle cells (SMCs). The optical scattering properties of collagen-SMC gels were characterized quantitatively by fitting OCT data to a theoretical model. Matrix remodeling over 5 days produced a 10-fold increase in the reflectivity of the collagen gels, corresponding to a decrease in scattering anisotropy from 0.91 to 0.46. The increase in reflectivity was corroborated in confocal mosaic images. Blocking matrix degradation in collagen-SMC gels with doxycycline, a non-specific matrix metalloproteinases (MMPs) inhibitor, impeded the decrease in scattering anisotropy and resulted in few macroscopic signs of remodeling. Causing matrix degradation in acellular gels with a 3 h treatment of MMP-8 (collagenase 2) partially mimicked the decrease in anisotropy measured in collagen-SMC gels after 5 days. These results suggest that the decrease in scattering anisotropy in the collagen-SMC gels was due to MMP activity that degrades collagen fibrils into smaller fragments.

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.

Tetracyclines: a pleitropic family of compounds with promising therapeutic properties. Review of the literature

There must be something unique about a class of drugs (discovered and developed in the mid-1940s) where there are more than 130 ongoing clinical trials currently listed. Tetracyclines were developed as a result of the screening of soil samples for antibiotic organisms. The first of these compounds chlortetracycline was introduced in 1948. Soon after their development tetracyclines were found to be highly effective against various pathogens including rickettsiae, Gram-positive, and Gram-negative bacteria, thus, becoming a class of broad-spectrum antibiotics. The mechanism of action of tetracyclines is thought to be related to the inhibition of protein synthesis by binding to the 30S bacterial ribosome. Tetracyclines are also an effective anti-malarial drug. Over time, many other "protective" actions have been described for tetracyclines. Minocycline, which can readily cross cell membranes, is known to be a potent anti-apoptotic agent. Its mechanism of action appears to relate to specific effects exerted on apoptosis signaling pathways. Another tetracycline, doxycycline is known to exert antiprotease activities. Doxycycline can inhibit matrix metalloproteinases, which contribute to tissue destruction activities in diseases such as gingivitis. A large body of literature has provided additional evidence for the "beneficial" actions of tetracyclines, including their ability to act as oxygen radical scavengers and anti-inflammatory agents. This increasing volume of published work and ongoing clinical trials supports the notion that a more systematic examination of their possible therapeutic uses is warranted. This review provides a summary of tetracycline's multiple mechanisms of action and while using the effects on the heart as an example, this review also notes their potential to benefit patients suffering from various pathologies such as cancer, Rosacea, and Parkinson's disease.

Rana catesbeiana, pólvora e modulação supramolecular cicatrização intestinal e prognóstico no câncer de cólon: uma mesma origem biológica para o insucesso?

A cicatrização e remodelação do cólon resultam das modificações do colágeno na matriz extracelular. Algumas condições desequilibram sua renovação, enfraquecendo a resistência mecânica a cicatriz, como resultado da atividade elevada das metaloproteinases locais, e levando a um alto risco de deiscência. As metaloproteinases da matriz extracelular (matrix metalloproteinases, MMPs) constituem uma família de endopeptidases zinco-dependentes - metzincinas. São reconhecidos atualmente, em humanos, cerca de 24 genes responsáveis por cada uma delas. A colagenase (MMP-1) foi identificada por Gross e Lapière (1962) na cauda do girino da rã-touro americana. No câncer as MMPs tem ocupado um lugar especial. Evidências de que a célula neoplásica é capaz de interferir na modulação desta enzima - um co-fator associado à invasividade local e disseminação metastática. As MMP-2 e -7 são observadas com frequência no câncer de cólon, a MMP-12 parece exercer um efeito protetor (melhor prognóstico) e, ao contrário, a MMP-3 o torna pior. A associação entre alta atividade de MMPs, o pior prognóstico do câncer e o maior risco de deiscência de anastomose intestinal já vem sendo considerada, sugerindo uma trilogia consistente. A terapia farmacológica (inibidores MMPs) tem sido investigada, também para o controle do câncer. O artigo discute as informações mais relevantes e atualizadas sobre o assunto.

Use of a specific MMP-inhibitor (galardin) for preservation of hybrid layer

OBJECTIVE

Dentinal MMPs have been claimed to contribute to the auto-degradation of collagen fibrils within incompletely resin-infiltrated hybrid layers and their inhibition may, therefore, slow the degradation of hybrid layer. This study aimed to determine the contribution of a synthetic MMPs inhibitor (galardin) to the proteolytic activity of dentinal MMPs and to the morphological and mechanical features of hybrid layers after aging.

METHODS

Dentin powder obtained from human molars was treated with galardin or chlorhexidine digluconate and zymographically analyzed. Microtensile bond strength was also evaluated in extracted human teeth. Exposed dentin was etched with 35% phosphoric acid and specimens were assigned to (1) pre-treatment with galardin as additional primer for 30s and (2) no pre-treatment. A two-step etch-and-rinse adhesive (Adper Scotchbond 1XT, 3M ESPE) was then applied in accordance with manufacturer's instructions and resin composite build-ups were created. Specimens were immediately tested for their microtensile bond strength or stored in artificial saliva for 12 months prior to being tested. Data were evaluated by two-way ANOVA and Tukey's tests (alpha=0.05). Additional specimens were prepared for interfacial nanoleakage analysis under light microscopy and TEM, quantified by two independent observers and statistically analyzed (chi(2) test, alpha=0.05).

RESULTS

The inhibitory effect of galardin on dentinal MMPs was confirmed by zymographic analysis, as complete inhibition of both MMP-2 and -9 was observed. The use of galardin had no effect on immediate bond strength, while it significantly decreased bond degradation after 1 year (p<0.05). Interfacial nanoleakage expression after aging revealed reduced silver deposits in galardin-treated specimens compared to controls (p<0.05).

CONCLUSIONS

This study confirmed that the proteolytic activity of dentinal MMPs was inhibited by the use of galardin in a therapeutic primer. Galardin also partially preserved the mechanical integrity of the hybrid layer created by a two-step etch-and-rinse adhesive after artificial aging.

Inhibition of matrix metalloproteinase-9 activity improves coronary outcome in an animal model of Kawasaki disease

Kawasaki disease (KD) is the leading cause of acquired heart disease of children in North America. It is characterized by a massive immune activation and multi-system vasculitis, which evolves into a site-specific inflammatory response focused at the coronary arteries. Coronary artery (CA) inflammation leads to elastin breakdown, destruction of the vessel wall and aneurysm formation. We have demonstrated recently the pivotal role of tumour necrosis factor (TNF)-alpha-mediated matrix metalloproteinase (MMP)-9 activity in the pathogenesis of elastin breakdown in a murine model of KD, Lactobacillus casei cell wall extract-induced coronary arteritis. Using this model, we evaluated the in vitro effects of doxycycline, an antibiotic with MMP inhibitory function, in modulating key pathogenic stages of disease leading to CA damage. Doxycycline inhibits T cell activation and TNF-alpha production in peripheral immune cells, as assessed by thymidine incorporation and a TNF bioassay respectively. Additionally, doxycycline inhibits directly MMP-9 enzymatic activity derived from TNF-alpha-stimulated vascular smooth muscle cells as assayed by zymography. More importantly, in vivo treatment of Lactobacillus casei cell wall extract (LCWE)-injected mice with doxycycline reduces significantly the incidence of CA elastin breakdown and reduces loss of elastin. Therefore, doxycycline can mitigate TNF-alpha-induced MMP-9-mediated coronary elastin breakdown and improve coronary outcome. Agents with the ability to inhibit both inflammation and the downstream effects of inflammation, such as MMP-9 activity, offer a promising therapeutic strategy for the management of children with KD.

Safety and efficacy of doxycycline in the treatment of rosacea

Rosacea is a common, chronic, skin condition characterized by recurrent episodes of facial flushing, transient or persistent erythema, papules, pustules, and telangiectasias, in a symmetrical facial distribution. The etiology of rosacea remains unknown and this condition represents a therapeutic challenge because of its chronic nature, progression, potential for disfigurement and psychological impact. Although there is no curative therapy for rosacea, the most widely used systemic agents are oral tetracycline derivatives, including tetracycline, doxycycline, and minocycline. This article reviews the available evidence for the use of doxycycline, a second-generation tetracycline, in the treatment or rosacea.

Maintenance of adrenergic vascular tone by MMP transactivation of the EGFR requires PI3K and mitochondrial ATP synthesis

AIMS

G-protein-coupled receptors (GPCRs) modulate vascular tone, at least in part, via matrix metalloproteinase (MMP) transactivation of the epidermal growth factor receptor (EGFR). We previously have identified novel signalling pathways downstream of the EGFR suggestive of mitogen-activated protein kinase and mitochondrial redox control of vascular tone. In the present study, we examined whether MMP modulation of vascular tone involves phosphoinositide 3-kinase (PI3K) and mitochondrial ATP synthesis.

METHODS AND RESULTS

To determine whether PI3K is required for the maintenance of adrenergic vascular tone, we first constricted rat small mesenteric arteries with phenylephrine (PE) and then perfused with PI3K inhibitors, LY294002 and wortmannin, both of which produced a dose-dependent vasodilatation. Next, to investigate whether MMPs modulate PI3K activity, we cultured rat aortic vascular smooth muscle cells (VSMCs) and stimulated them with GPCR agonists such as PE and angiotensin II. Inhibition of MMPs (by GM6001) or EGFR (by AG1478) or suppressing the expression of MMP-2 or MMP-7 or the EGFR by small interfering RNA blunted the PI3K phosphorylation of Akt induced by PE. Further, in VSMCs, PI3K inhibitors reduced the PE-induced increase in ATP synthesis and glucose transporter-4 translocation, an effect that was also observed with MMP and the EGFR inhibitors. Further, the PE-induced increase in ATP synthesis activated MMP-7 by mechanisms involving purinergic (P2X) receptors and calcium.

CONCLUSION

These data suggest that the maintenance of adrenergic vascular tone by the MMP-EGFR pathway requires PI3K activation and ATP synthesis. Further, our data support the view that elevated levels of GPCR agonists exaggerate the MMP transactivation of EGFR response and contribute to enhanced vascular tone and development of cardiovascular disease such as hypertension.

Clinical assessment of the effect of a matrix metalloproteinase inhibitor on aphthous ulcers

OBJECTIVE

Aphthous ulceration is a common form of recurrent ulceration of the oral mucosa. Numerous treatments have been tried as a means of relieving pain, disinfecting the ulcer base, and reducing inflammation, but with limited success. Tetracycline and its derivatives have been shown to be inhibitors of matrix metalloproteinases (MMPs), which are part of the inflammatory response and contribute to the breakdown of tissue in the ulcer. Of the commercially available tetracyclines, doxycycline has shown the best inhibition of the MMPs. The aim of this study was to test clinically whether the inhibitory effect of a low-dose doxycycline in a hydrogel on MMPs would speed the recovery of oral ulceration.

MATERIAL AND METHODS

Forty-nine patients participated in a randomized, double-blind, placebo-controlled trial.

RESULTS

Sixty-eight percent of ulcers had healed by the third day of treatment with the doxycycline gel, whereas only 25% of the patients receiving the placebo reported healing of their ulcers within 3 days. Patients treated with the docycline gel recounted faster reduction in pain during the treatment period than the placebo group did.

CONCLUSIONS

Incorporation of low-dose doxycycline in a muco-adhesive gel has been demonstrated to have potential in the treatment of recurrent oral ulceration. It is concluded that MMP enzymes can be inhibited by low doses of doxycycline below levels likely to disrupt the oral flora.

Attacking the multi-tiered proteolytic pathology of COPD: new insights from basic and translational studies

Protease activity in inflammation is complex. Proteases released by cells in response to infection, cytokines, or environmental triggers like cigarette smoking cause breakdown of the extracellular matrix (ECM). In chronic inflammatory diseases like chronic obstructive pulmonary disease (COPD), current findings indicate that pathology and morbidity are driven by dysregulation of protease activity, either through hyperactivity of proteases or deficiency or dysfunction their antiprotease regulators. Animal studies demonstrate the accuracy of this hypothesis through genetic and pharmacologic tools. New work shows that ECM destruction generates peptide fragments active on leukocytes via neutrophil or macrophage chemotaxis towards collagen and elastin derived peptides respectively. Such fragments now have been isolated and characterized in vivo in each case. Collectively, this describes a biochemical circuit in which protease activity leads to activation of local immunocytes, which in turn release cytokines and more proteases, leading to further leukocyte infiltration and cyclical disease progression that is chronic. This circuit concept is well known, and is intrinsic to the protease-antiprotease hypothesis; recently analytic techniques have become sensitive enough to establish fundamental mechanisms of this hypothesis, and basic and clinical data now implicate protease activity and peptide signaling as pathologically significant pharmacologic targets. This review discusses targeting protease activity for chronic inflammatory disease with special attention to COPD, covering important basic and clinical findings in the field; novel therapeutic strategies in animal or human studies; and a perspective on the successes and failures of agents with a focus on clinical potential in human disease.

Subantimicrobial-dose doxycycline modulates gingival crevicular fluid biomarkers of periodontitis in postmenopausal osteopenic women

BACKGROUND

We recently demonstrated that a 2-year subantimicrobial-dose doxycycline (SDD) regimen (double-masked, placebo-controlled clinical trial) in postmenopausal (PM) women exhibiting mild systemic bone loss (osteopenia) and local bone loss (periodontitis) reduced the progression of periodontal attachment loss (intent-to-treat analysis) and the severity of gingival inflammation and alveolar bone loss (subgroups) without producing antibiotic side effects. We now describe SDD effects on biomarkers of collagen degradation and bone resorption in the gingival crevicular fluid (GCF) of the same vulnerable subjects.

METHODS

GCF was collected from SDD- and placebo-treated PM subjects (n=64 each) at the baseline and 1- and 2-year appointments; the volume was determined; and the samples were analyzed for collagenase activity (using a synthetic peptide as substrate), relative levels of three genetically distinct collagenases (Western blot), a type-1 collagen breakdown product/bone resorption marker (a carboxyterminal telopeptide cross-link fragment of type I collagen [ICTP]; radioimmunoassay), and interleukin-1beta (enzyme-linked immunosorbent assay). Statistical analyses were performed using generalized estimating equations; primary analyses were intent-to-treat.

RESULTS

Collagenase activity was significantly reduced by SDD treatment relative to placebo based on intent-to-treat (P=0.01). ICTP showed a similar pattern of change during SDD treatment, and GCF collagenase activity and ICTP were positively correlated at all time periods (P<0.001). Matrix metalloproteinase (MMP)-8 accounted for approximately 80% of total collagenase in GCF, with much less MMP-1 and -13, and SDD reduced the odds of elevated MMP-8 by 60% compared to placebo (P=0.006).

CONCLUSION

These observations support the therapeutic potential of long-term SDD therapy to reduce periodontal collagen breakdown and alveolar bone resorption in PM women; effects on serum biomarkers of systemic bone loss in these subjects are being analyzed.

Antibody responses to Porphyromonas gingivalis (P. gingivalis) in subjects with rheumatoid arthritis and periodontitis

Antibody titers to P. gingivalis are increased in patients with rheumatoid arthritis and are associated with disease-specific autoimmunity.

BACKGROUND

Periodontitis (PD) has been implicated as a risk factor for rheumatoid arthritis (RA). We sought to characterize antibody titers to P. gingivalis (a pathogen in PD) in subjects with RA, PD, and in healthy controls and to examine their relationship with disease autoantibodies.

METHODS

P. gingivalis antibody was measured in subjects with RA (n=78), PD (n=39), and in controls (n=40). Group frequencies of bacterial titer elevations were compared using the Chi-square test and antibody titers were compared using non-parametric tests. Correlations of P. gingivalis titer with C-reactive protein (CRP), antibody to cyclic citrullinated peptide (anti-CCP), and rheumatoid factor (RF) were examined in those with RA while CRP and autoantibody concentrations were compared based on seropositivity to P. gingivalis.

RESULTS

Antibody titers to P. gingivalis were highest in PD, lowest in controls, and intermediate in RA (p=0.0003). Elevations in P. gingivalis (titer> or =800) were more common in RA and PD (67% and 77%, respectively) than in controls (40%) (p=0.002). In RA, there were significant correlations with P. gingivalis titer with CRP, anti-CCP-IgM, and -IgG-2. CRP (p=0.006), anti-CCP-IgM (p=0.01) and -IgG2 (p=0.04) concentrations were higher in RA cases with P. gingivalis titers > or =800 compared to cases with titers <800.

CONCLUSION

Antibodies to P. gingivalis are more common in RA subjects than controls, although lower than that in PD. Associations of P. gingivalis titers with RA-related autoantibody and CRP concentrations suggests that infection with this organism plays a role in disease risk and progression in RA.

Inhibitory effect of oral doxycycline on neovascularization in a rat corneal alkali burn model of angiogenesis

PURPOSE

To examine the efficacy of oral doxycycline treatment (as compared to oral and topical dexamethasone) for inhibiting corneal neovascularization (CNV).

METHODS

Following corneal alkali burn, rats were treated daily with oral doxycycline, oral dexamethasone, or topical dexamethasone for 14 days. Control rats were injured but were not treated. At days 3, 7, and 14 post injury, length and area of CNV were evaluated, as well as corneal epithelial healing and ulceration. Tissues were obtained from a subset of rats from each group for histopathological analysis.

RESULTS

At days 7 and 14 post-injury, CNV length in the doxycycline group was significantly less than in the untreated control (p < 0.008). The area of CNV was significantly smaller in doxycycline as compared to control rats on days 3, 7, and 14 post-injury. Inhibition of CNV (indicated by area and length) was significantly greater in both dexamethasone groups compared to the doxycycline group (p < 0.008 for all comparisons). However, epithelial healing was significantly more rapid in the doxycycline group compared to both dexamethasone groups (p < 0.008). Epithelial ulceration was apparent in both oral and topically treated dexamethasone rats, but not in doxycycline-treated rats.

CONCLUSIONS

Oral doxycycline inhibits CNV without the harmful side effects associated with dexamethasone use. Further investigation is warranted to assess the mechanisms through which doxycycline acts to cause CNV inhibition, and the applicability of doxycycline use for treating CNV in the clinical setting.

Increased activities of cardiac matrix metalloproteinases matrix metalloproteinase (MMP)-2 and MMP-9 are associated with mortality during the acute phase of experimental Trypanosoma cruzi infection

The strong inflammatory reaction that occurs in the heart during the acute phase of Trypanosoma cruzi infection is modulated by cytokines and chemokines produced by leukocytes and cardiomyocytes. Matrix metalloproteinases (MMPs) have recently emerged as modulators of cardiovascular inflammation. In the present study we investigated the role of MMP-2 and MMP-9 in T. cruzi-induced myocarditis, by use of immunohistochemical analysis, gelatin zymography, enzyme-linked immunosorbent assay, and real-time polymerase chain reaction to analyze the cardiac tissues of T. cruzi-infected C57BL/6 mice. Increased transcripts levels, immunoreactivity, and enzymatic activity for MMP-2 and MMP-9 were observed by day 14 after infection. Mice treated with an MMP inhibitor showed significantly decreased heart inflammation, delayed peak in parasitemia, and improved survival rates, compared with the control group. Reduced levels of cardiac tumor necrosis factor-alpha, interferon-gamma, serum nitrite, and serum nitrate were also observed in the treated group. These results suggest an important role for MMPs in the induction of T. cruzi-induced acute myocarditis.

Tetracycline suppresses ATP gamma S-induced CXCL8 and CXCL1 production by the human dermal microvascular endothelial cell-1 (HMEC-1) cell line and primary human dermal microvascular endothelial cells

Tetracyclines (TCN) have powerful anti-inflammatory properties in addition to their anti-microbial effects. These anti-inflammatory effects are thought to play a role in inhibiting cutaneous inflammation in patients with rosacea and acne; however, the mechanism(s) of this action remains poorly understood. We have previously shown that adenosine-5'-triphosphate (ATP)gamma S, a hydrolysis-resistant ATP analogue, augments secretion of pro-inflammatory messengers by a human dermal microvascular endothelial cell line (HMEC-1). ATP released by the sympathetic nerves during stress may stimulate release of pro-inflammatory chemokines by dermal vessel endothelial cells, resulting in recruitment of inflammatory cells and exacerbation of inflammatory skin disease. Here we demonstrate that TCN inhibits ATP gamma S-induced release of pro-inflammatory mediators by HMEC-1 cells and primary human dermal microvascular endothelial cells. TCN dose-dependently inhibited ATP gamma S-induced augmentation of CXCL8 (interleukin-8) and CXCL1 (growth-regulated oncogene-alpha) production by HMEC-1 cells and primary human dermal endothelial cells in vitro. TCN and ATP gamma S did not affect HMEC-1 cell viability as determined by trypan-blue exclusion and cell counts. Inhibition of production of inflammatory mediators by endothelial cells may be one mechanism by which TCN improves inflammatory skin diseases. The ability to inhibit release of inflammatory mediators induced in HMEC-1 cells by purinergic agonists may be a useful way to screen for potential therapeutic agents for cutaneous inflammation.

Subantimicrobial dose doxycycline effects on alveolar bone loss in post-menopausal women

AIM

Determine the efficacy of 2-year continuous subantimicrobial dose doxycycline (SDD; 20 mg bid) on alveolar bone in post-menopausal osteopenic, oestrogen-deficient women undergoing periodontal maintenance in a 2-year double-blind, placebo-controlled, randomized clinical trial.

MATERIAL AND METHODS

One-hundred and twenty-eight subjects randomized to SDD or placebo (n=64 each). Posterior vertical bite wings taken at baseline, 1 and 2 years for alveolar bone density (ABD), using radiographic absorptiometry (RA) and computer-assisted densitometric image analysis (CADIA), and alveolar bone height (ABH). Statistical analyses utilized generalized estimating equations; primary analyses were intent to treat (ITT). Results are presented as SDD versus placebo.

RESULTS

Under ITT, there was no statistically significant effect of SDD on ABD loss (RA: p=0.8; CADIA: p=0.2) or ABH loss (p=0.2). Most sites (81-95%) were inactive. For subgroup analyses, mean CADIA was higher with SDD for non-smokers (p=0.05) and baseline probing depths > or =5 mm (p=0.003). SDD was associated with 29% lower odds of more progressive ABH loss in women >5 years post-menopausal (p=0.05) and 36% lower among protocol-adherent subjects (p=0.03).

CONCLUSIONS

In post-menopausal osteopenic women with periodontitis, SDD did not differ overall from placebo. Based on exploratory subgroup analyses, additional research is needed to determine the usefulness of SDD in non-smokers, subjects >5 years post-menopausal and in deeper pockets. Protocol registered at (ClinicalTrials.gov). Identifier: NCT00066027.

Profiling Protein Arginine Deiminase 4 (PAD4): a novel screen to identify PAD4 inhibitors

Protein Arginine Deiminase 4 (PAD4) has emerged as a leading target for the development of a Rheumatoid Arthritis (RA) pharmaceutical. Herein, we describe the development of a novel screen for PAD4 inhibitors that is based on a PAD4-targeted Activity-Based Protein Profiling reagent, denoted Rhodamine-conjugated F-Amidine (RFA). This screen was validated by screening 10 Disease Modifying Anti-Rheumatic Drugs (DMARDs) and identified streptomycin, minocycline, and chlortetracycline as micromolar inhibitors of PAD4 activity.

Upper respiratory tract infection in household contacts of acne patients

BACKGROUND

Antibiotic use in acne patients has been associated with an increased risk of upper respiratory tract infection (URTI).

METHODS

This was a retrospective cohort study using the General Practice Research Database of the United Kingdom. All study subjects were identified as sharing a residence with a patient with a diagnosis of acne. Outcome of interest was a URTI.

RESULTS

We identified 98,094 contacts of acne patients. A contact of an acne patient who had a URTI was about 43% more likely to develop a URTI than a contact of an acne patient who did not have a URTI (OR = 1.43 CI = 1.33-1.52, p < 0.001). Exposure to an acne patient using antibiotics did not independently increase a contact's risk of URTI (OR = 0.94, CI = 0.89-1.00, p = 0.063).

CONCLUSIONS

Although acne patients on antibiotics are about 2 times more likely to develop URTIs, their household contacts do not appear to be at an increased risk of URTI.

Anti-inflammatory dose doxycycline (40 mg controlled-release) confers maximum anti-inflammatory efficacy in rosacea

BACKGROUND

Two large clinical trials have recently demonstrated the efficacy of a 40-mg controlled-release formulation of doxycycline in the treatment of rosacea, a dose well below the conventional level of 100 to 200 mg/d. Since no formal dose-response studies have been conducted, the authors analyzed phase 3 data to determine whether a dose-efficacy relationship exists.

METHODS

Standard parametric regression analyses were used to estimate the correlations between dose (mg/kg body weight) and overall drug exposure (area under the curve [AUC]) in a phase 1 pharmacokinetic study and between dose and efficacy (mean change from baseline in total inflammatory lesion count at week 16) in 2 pooled phase 3 clinical efficacy studies. Additional regressions were run at each visit for the clinical efficacy studies to determine whether results differed across visits. A regression analysis was also performed in a subset of patients who showed a greater efficacy response.

RESULTS

We found overall drug exposure (AUC) to have a highly significant correlation with dose (mg/kg) (r=0.49; P=.006). In contrast, clinical efficacy did not correlate with dose at any of the visits at week 3 (r=0.01; P=.85), week 6 (r=0.04; P=.53), week 12 (r<0.01; P=.98), and week 16 (r=0.03; P=.64) or among the subset of patients who showed greater clinical benefit.

CONCLUSIONS

Higher mg/kg doses led to higher plasma concentrations but did not lead to increased clinical efficacy. Anti-inflammatory dose doxycycline (40-mg controlled-release formulation) conferred peak anti-inflammatory efficacy in the treatment of rosacea.