Novel host response therapeutic approaches to treat periodontal diseases

Black tea theaflavins attenuate Porphyromonas gingivalis virulence properties, modulate gingival keratinocyte tight junction integrity and exert anti-inflammatory activity

BACKGROUND AND OBJECTIVE

Over the last 10 years, bioactive plant food compounds have received considerable attention in regard to their beneficial effects against periodontal disease. In this study, we investigated the effects of black tea theaflavins (TFs) on the virulence properties of Porphyromonas gingivalis and gingival keratinocyte tight junction integrity. In addition, the effects of black tea TFs on the nuclear factor-κB (NF-κB) signaling pathway and proinflammatory cytokine/matrix metalloproteinase (MMP) secretion by monocytes/macrophages were assessed.

MATERIAL AND METHODS

Virulence factor gene expression in P. gingivalis was investigated by quantitative real-time PCR. A fluorescence assay was used to determine P. gingivalis adherence to, and invasion of, a gingival keratinocyte monolayer. Tight junction integrity of gingival keratinocytes was assessed by determination of transepithelial electrical resistance. Proinflammatory cytokine and MMP secretion by P. gingivalis-stimulated macrophages was quantified by ELISA. The U937-3xκB-LUC monocyte cell line transfected with a luciferase reporter gene was used to monitor NF-κB activation. Gelatin degradation was monitored using a fluorogenic assay.

RESULTS

Black tea TFs dose-dependently inhibited the expression of genes encoding the major virulence factors of P. gingivalis and attenuated its adherence to gingival keratinocytes. A treatment of gingival keratinocytes with black tea TFs significantly enhanced tight junction integrity and prevented P. gingivalis-mediated tight junction damage as well as bacterial invasion. Black tea TFs reduced the secretion of interleukin (IL)-1β, tumor necrosis factor-α, IL-6, chemokine (C-X-C) ligand 8, MMP-3, MMP-8 and MMP-9 by P. gingivalis-stimulated macrophages and attenuated the P. gingivalis-mediated activation of the NF-κB signaling pathway. Lastly, black tea TFs inhibited gelatin degradation by MMP-9.

CONCLUSION

This study provides clear evidence that black tea TFs represent promising multifunctional therapeutic agents for prevention and treatment of periodontal disease.

Sex-based differential regulation of bacterial-induced bone resorption

BACKGROUND AND OBJECTIVE

Periodontal disease pathogenesis is comprised of the complex inflammatory immune response to oral bacterial dysbiosis. Like other inflammatory diseases, there is sexual dimorphism evident in periodontal diseases. During periodontitis, inflammatory chemokines direct neutrophils to migrate to the site of infection to neutralize the pathogen. Interestingly, these same chemokines are also involved in regulating pathogen-induced osteoclast formation. Previous reports show differences in bone turnover and lymphocyte recruitment between sexes. We hypothesize that chemokine expression is differentially regulated by sex and thus results in differential osteoclast formation.

MATERIAL AND METHODS

Male and female mice were utilized to isolate neutrophils based on expression of Ly6G-specific, as well as defined osteoclast progenitors. Cells were stimulated with lipopolysaccharide (LPS; 100 ng/mL) then analyzed for neutrophil infiltration and gene expression. Defined osteoclast progenitors were primed: macrophage-colony stimulating factor (25 ng/mL), receptor activator of NF-κB ligand (50 ng/mL), then stimulated with LPS. Osteoclasts were enumerated via TRAP stain and mRNA isolated for gene expression analysis via quantitative polymerase chain reaction.

RESULTS

In response to LPS, male neutrophils in vitro respond with increased chemokine expression and significantly more osteoclast formed in response to LPS compared to females.

CONCLUSIONS

Findings support observations in humans regarding a sexual dimorphism in oral bacterial infections of alveolar bone loss. Males have a strong inflammatory response to bacterial infection, resulting in increased inflammatory microenvironment, reduced pathogenic bacteria clearance and increased osteoclast-driven bone loss in response to differential expression of key chemokines.

Platelet-Rich Fibrin Combined With 1.2% Atorvastatin for Treatment of Intrabony Defects in Chronic Periodontitis: A Randomized Controlled Clinical Trial

BACKGROUND

Platelet-rich fibrin (PRF), a second-generation platelet concentrate, and atorvastatin (ATV), a potent member of the statin group, are known to promote tissue regeneration. The current study is designed to evaluate combined efficacy of PRF and 1.2% ATV gel with open flap debridement (OFD) in treatment of intrabony defects (IBDs) in individuals with chronic periodontitis (CP).

METHODS

Ninety-six individuals with single defects were categorized into three groups: 1) OFD with PRF; 2) OFD with PRF + 1.2% ATV; and 3) OFD alone. Clinical parameters: 1) site-specific plaque index; 2) modified sulcus bleeding index; 3) probing depth (PD); 4) relative clinical attachment level (rCAL); and 5) gingival marginal level were recorded at baseline before surgery and 9 months postoperatively. Percentage radiographic IBD depth reduction was evaluated at baseline and 9 months.

RESULTS

PRF + 1.2% ATV and PRF alone showed significantly greater PD reduction and rCAL gain compared with OFD alone at 9 months. Furthermore, PRF + 1.2% ATV showed a similar percentage radiographic defect depth reduction (50.96% ± 4.88%) compared with PRF alone (47.91% ± 4.79%), and a greater reduction compared with OFD alone (5.54% ± 1.71%) at 9 months.

CONCLUSIONS

PRF + 1.2% ATV showed similar improvements in clinical parameters with a greater percentage radiographic defect depth reduction compared with PRF alone in treatment of IBDs in individuals with CP. Thus, 1.2% ATV failed to augment the regenerative potential of PRF alone in periodontal IBDs.

Determining whether curcumin degradation/condensation is actually bioactivation (Review)

Curcumin has been shown to exert therapeutic or protective effects against a variety of diseases, such as cancer, pulmonary diseases, neurological, liver, metabolic, autoimmune, cardiovascular diseases and numerous other chronic ailments. Over 116 clinical studies on curcumin in humans were registered with the US National Institutes of Health in 2015. However, it is mystifying how curcumin can be so effective in the treatment of many diseases since it has very low water solubility and bioavailability. Furthermore, curcumin is not stable under various conditions; its degradation or condensation into different bioactive compounds may be responsible for its biological activities rather than curcumin itself. In this review, we provide evidence of curcumin degradation and condensation into different compounds which have or may have health benefits themselves. Literature reviews strongly suggest that these molecules contribute to the observed health benefits, rather than curcumin itself.

Role of nitro-oxidative stress in the pathogenesis of experimental rat periodontitis

Background and aims

Periodontitis is a common chronic adult condition that implicates oxidative damage to gingival tissue, periodontal ligament and alveolar bone. This study aimed at assessing the association between the nitro-oxidative stress and the periodontal tissues destructions in experimental rat periodontitis.

Methods

Periodontitis was induced in 15 male albino rats by repetitive lesions to the gingiva adjacent to the inferior incisors, performed daily, for 16 days. On D1, D3, D6, D8, and D16 the onset and evolution of periodontitis were monitored by clinical and histopathological examinations; blood was collected and serum nitro-oxidative stress was evaluated through total nitrites and nitrates, total oxidative status, total antioxidant capacity, and oxidative stress index.

Results

The results demonstrated that there was a graded and continuous increase in serum levels of total nitrites and nitrates, total oxidative status and oxidative stress index, which was consistent with the severity of periodontal destructions during periodontitis progression. However, total antioxidant capacity was not significantly influenced by the disease progression.

Conclusions

In experimental rat periodontitis, the systemic nitro-oxidative stress was associated with the severity of periodontal destructions assessed clinically and histopathologically. Therefore, systemic nitro-oxidative stress parameters might be used as diagnostic tools in periodontitis.

Ethical guidelines, animal profile, various animal models used in periodontal research with alternatives and future perspectives

Laboratory animal models serve as a facilitator to investigate the etiopathogenesis of periodontal disease, are used to know the efficacy of reconstructive and regenerative procedures, and are also helpful in evaluation of newer therapeutic techniques including laser and implant therapies prior to application in the human beings. The aim of this review is to know the different animal models used in various specialties of dental research and to know the ethical guidelines prior to the usage of experimental models with main emphasis on how to refine, replace, and reduce the number of animal models usage in the laboratory. An online search for experimental animal models used in dental research was performed using MEDLINE/PubMed database. Publications from 2009 to May 2013 in the specialty of periodontics were included in writing this review. A total of 652 references were published in PubMed/MEDLINE databases based on the search terms used. Out of 245 studies, 241 were related to the periodontal research published in English from 2009 to 2013. Relevant papers were chosen according to the inclusion and exclusion criteria. After extensive electronic and hand search on animal models, it has been observed that various animal models were used in dental research. Search on animal models used for dental research purpose revealed that various animals such as rats, mice, guinea pigs, rabbit, beagle dogs, goats, and nonhuman primates were extensively used. However, with the new advancement of ex vivo animal models, it has become easy to investigate disease pathogenesis and to test the efficacy of newer therapeutic modalities with the reduced usage of animal models. This review summarized the large amount of literature on animal models used in periodontal research with main emphasis on ethical guidelines and on reducing the animal model usage in future perspective.

Chemically modified tetracyclines: The novel host modulating agents

Periodontal pathogens and destructive host responses are involved in the initiation and progression of periodontitis. The emergence of host response modulation as a treatment concept has resulted from our improved understanding of the pathogenesis of periodontal disease. A variety of drugs have been evaluated as host modulation agents (HMA), including Non Steroidal Anti Inflammatory Drugs (NSAIDS), bisphosphonates, tetracyclines, enamel matrix proteins and bone morphogenetic proteins. Chemically modified tetracyclines (CMTs) are one such group of drugs which have been viewed as potential host modulating agents by their anticollagenolytic property. The CMTs are designed to be more potent inhibitors of pro inflammatory mediators and can increase the levels of anti inflammatory mediators.

Vitamin D inhibits the growth of and virulence factor gene expression by Porphyromonas gingivalis and blocks activation of the nuclear factor kappa B transcription factor in monocytes

BACKGROUND AND OBJECTIVE

Increasing evidence suggests that 1,25-dihydroxyvitamin D3 (1,25(OH)2 D3 ), a fat-soluble secosteroid hormone, has a positive impact on periodontal health through diverse mechanisms. The present study was aimed at investigating the effect of 1,25(OH)2 D3 on the growth of and virulence factor gene expression by the periodontopathogenic bacterium Porphyromonas gingivalis. The effect of 1,25(OH)2 D3 on P. gingivalis-mediated activation of nuclear factor kappa B (NF-κB) transcription factor in monocytes was also assessed.

MATERIAL AND METHODS

A broth microdilution assay was used to determine the antibacterial activity of 1,25(OH)2 D3 . The modulation of virulence factor gene expression in P. gingivalis was assessed by quantitative reverse transcription-polymerase chain reaction. NF-κB activation was assessed using a human monocytic cell line stably transfected with a luciferase reporter containing NF-κB binding sites.

RESULTS

Minimal inhibitory concentrations of 1,25(OH)2 D3 against P. gingivalis ranged from 3.125 to 6.25 μg/mL. Moreover, a partial synergistic effect was observed when 1,25(OH)2 D3 was used in association with metronidazole. 1,25(OH)2 D3 attenuated the virulence of P. gingivalis by reducing the expression of genes coding for important virulence factors, including adhesins (fimA, hagA and hagB) and proteinases (rgpA, rgpB and kgp). 1,25(OH)2 D3 dose-dependently prevented P. gingivalis-induced NF-κB activation in a monocyte model.

CONCLUSION

Our study suggested that 1,25(OH)2 D3 selectively inhibits the growth of and virulence factor gene expression by P. gingivalis, in addition to attenuating NF-κB activation by this periodontopathogen. This dual action on P. gingivalis and the inflammatory response of host cells may be of particular interest with a view to developing a novel and inexpensive preventive/therapeutic strategy.

Salivary Visfatin Concentration in Response to Non-surgical Periodontal Therapy

INTRODUCTION

Visfatin is a pro-inflammatory cytokine that has been associated with several immunomodulating processes. The relationship between visfatin and periodontitis has been the subject of a few studies that have described visfatin as an inflammatory marker for periodontitis. However, studies on visfatin as a potential therapeutic target in periodontal diseases are scarce. In the present study, we evaluated the alterations in salivary visfatin levels in response to non-surgical periodontal treatment.

MATERIALS AND METHODS

Twenty individuals with moderate to severe chronic periodontitis and twenty periodontally healthy individuals were selected for this study according to clinical parameters. Patients with chronic periodontitis were treated by non-surgical periodontal therapy. Clinical parameters were recorded and saliva samples were obtained from the control group and test group before (T1 group) and one month after periodontal treatment (T2 group). Salivary visfatin concentrations were measured by standard enzyme-linked immunosorbent assay (ELISA). Statistical analysis was performed with the statistical software SPSS, version 18.

RESULTS

Visfatin was detectable in all samples. T1 and control groups were significantly different in terms of clinical parameters and visfatin levels. Visfatin concentrations were reduced significantly after non-surgical periodontal therapy. Periodontal treatment also resulted in significant reductions of all clinical parameters with the exception of clinical attachment level.

CONCLUSION

The results demonstrated that salivary levels of visfatin are reduced after non-surgical periodontal therapy to the levels comparable with those found in healthy individuals. Therefore, the salivary visfatin level may have the potential to be a target marker for assessment of responses to non-surgical periodontal therapy. However, more studies with larger sample sizes are necessary to validate these findings.

The effect of blue light on periodontal biofilm growth in vitro

We have previously shown that blue light eliminates the black-pigmented oral bacteria Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens, and Prevotella melaninogenica. In the present study, the in vitro photosensitivity of the above black-pigmented microorganisms and four Fusobacteria species (Fusobacterium nucleatum ss. nucleatum, F. nucleatum ss. vincentii, F. nucleatum ss. polymorphum, Fusobacterium periodonticum) was investigated in pure cultures and human dental plaque suspensions. We also tested the hypothesis that phototargeting the above eight key periodontopathogens in plaque-derived biofilms in vitro would control growth within the dental biofilm environment. Cultures of the eight bacteria were exposed to blue light at 455 nm with power density of 80 mW/cm2 and energy fluence of 4.8 J/cm2. High-performance liquid chromatography (HPLC) analysis of bacteria was performed to demonstrate the presence and amounts of porphyrin molecules within microorganisms. Suspensions of human dental plaque bacteria were also exposed once to blue light at 455 nm with power density of 50 mW/cm2 and energy fluence of 12 J/cm2. Microbial biofilms developed from the same plaque were exposed to 455 nm blue light at 50 mW/cm2 once daily for 4 min (12 J/cm2) over a period of 3 days (4 exposures) in order to investigate the cumulative action of phototherapy on the eight photosensitive pathogens as well as on biofilm growth. Bacterial growth was evaluated using the colony-forming unit (CFU) assay. The selective phototargeting of pathogens was studied using whole genomic probes in the checkerboard DNA-DNA format. In cultures, all eight species showed significant growth reduction (p < 0.05). HPLC demonstrated various porphyrin patterns and amounts of porphyrins in bacteria. Following phototherapy, the mean survival fractions were reduced by 28.5 and 48.2% in plaque suspensions and biofilms, respectively, (p < 0.05). DNA probe analysis showed significant reduction in relative abundances of the eight bacteria as a group in plaque suspensions and biofilms. The cumulative blue light treatment suppressed biofilm growth in vitro. This may introduce a new avenue of prophylactic treatment for periodontal diseases.

Green tea polyphenol epigallocatechin-3-gallate and cranberry proanthocyanidins act in synergy with cathelicidin (LL-37) to reduce the LPS-induced inflammatory response in a three-dimensional co-culture model of gingival epithelial cells and fibroblasts

OBJECTIVES

The human antimicrobial peptide cathelicidin (LL-37) possesses anti-inflammatory properties that may contribute to attenuating the inflammatory process associated with chronic periodontitis. Plant polyphenols, including those from cranberry and green tea, have been reported to reduce inflammatory cytokine secretion by host cells. In the present study, we hypothesized that A-type cranberry proanthocyanidins (AC-PACs) and green tea epigallocatechin-3-gallate (EGCG) act in synergy with LL-37 to reduce the secretion of inflammatory mediators by oral mucosal cells.

METHODS

A three-dimensional (3D) co-culture model of gingival epithelial cells and fibroblasts treated with non-cytotoxic concentrations of AC-PACs (25 and 50 μg/ml), EGCG (1 and 5 μg/ml), and LL-37 (0.1 and 0.2 μM) individually and in combination (AC-PACs+LL-37 and EGCG+LL-37) were stimulated with Aggregatibacter actinomycetemcomitans lipopolysaccharide (LPS). Multiplex ELISA assays were used to quantify the secretion of 54 host factors, including chemokines, cytokines, growth factors, matrix metalloproteinases (MMPs), and tissue inhibitors of metalloproteinases (TIMPs).

RESULTS

LL-37, AC-PACs, and EGCG, individually or in combination, had no effect on the regulation of MMP and TIMP secretion but inhibited the secretion of several cytokines. AC-PACs and LL-37 acted in synergy to reduce the secretion of CXC-chemokine ligand 1 (GRO-α), granulocyte colony-stimulating factor (G-CSF), and interleukin-6 (IL-6), and had an additive effect on reducing the secretion of interleukin-8 (IL-8), interferon-γ inducible protein 10 (IP-10), and monocyte chemoattractant protein-1 (MCP-1) in response to LPS stimulation. EGCG and LL-37 acted in synergy to reduce the secretion of GRO-α, G-CSF, IL-6, IL-8, and IP-10, and had an additive effect on MCP-1 secretion.

CONCLUSION

The combination of LL-37 and natural polyphenols from cranberry and green tea acted in synergy to reduce the secretion of several cytokines by an LPS-stimulated 3D co-culture model of oral mucosal cells. Such combinations show promising results as potential adjunctive therapies for treating inflammatory periodontitis.

Non-surgical periodontal therapy: An update on current evidence

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

Detection of rankl positive cells in gingival tissue in healthy & chronic periodontal disease patients-a comparative study

Aim & Objective: The receptor activator of NF-kappa B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG), are the important proteins implicated in osteoclastogenesis. This study aimed to identify & quantify RANKL positive cells in gingival tissues in healthy & diseased patients & the study looks for immunohistochemical evidence of the expression of the protein in gingival tissue samples.

MATERIALS AND METHODS

Patients were randomly selected. Thirty subject each for (test & control). Age range of 25-55y, either sex was selected. Tissue samples were collected from Control - Healthy Gingiva & Test-Chronic Periodontitis Patients. Tissue sections were prepared. An Immunohistochemical analysis was done & cell counting was done for RANKL positive cells.

RESULTS

Immunohistochemical staining showed that RANKL-positive cells were significantly distributed in the inflammatory epithelium & connective tissue zone of diseased & non-diseased gingiva. RANKL, positive cells was increased significantly in patients with chronic periodontitis (p < 0.05).

CONCLUSION

These findings imply that in this comparative study of gingival tissue for, RANKL positive cells, these cells were present in both healthy & chronic periodontitis samples, but number of positive cells present is significantly increased in chronic periodontitis.

Minocycline: far beyond an antibiotic

Minocycline is a second-generation, semi-synthetic tetracycline that has been in therapeutic use for over 30 years because of its antibiotic properties against both gram-positive and gram-negative bacteria. It is mainly used in the treatment of acne vulgaris and some sexually transmitted diseases. Recently, it has been reported that tetracyclines can exert a variety of biological actions that are independent of their anti-microbial activity, including anti-inflammatory and anti-apoptotic activities, and inhibition of proteolysis, angiogenesis and tumour metastasis. These findings specifically concern to minocycline as it has recently been found to have multiple non-antibiotic biological effects that are beneficial in experimental models of various diseases with an inflammatory basis, including dermatitis, periodontitis, atherosclerosis and autoimmune disorders such as rheumatoid arthritis and inflammatory bowel disease. Of note, minocycline has also emerged as the most effective tetracycline derivative at providing neuroprotection. This effect has been confirmed in experimental models of ischaemia, traumatic brain injury and neuropathic pain, and of several neurodegenerative conditions including Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, Alzheimer's disease, multiple sclerosis and spinal cord injury. Moreover, other pre-clinical studies have shown its ability to inhibit malignant cell growth and activation and replication of human immunodeficiency virus, and to prevent bone resorption. Considering the above-mentioned findings, this review will cover the most important topics in the pharmacology of minocycline to date, supporting its evaluation as a new therapeutic approach for many of the diseases described herein.

The inflammophilic character of the periodontitis-associated microbiota

In periodontitis, dysbiotic microbial communities exhibit synergistic interactions for enhanced protection from host defenses, nutrient acquisition, and persistence in an inflammatory environment. This review discusses evidence that periodontitis-associated communities are 'inflammo-philic' (=loving or attracted to inflammation) in that they have evolved to not only endure inflammation but also to take advantage of it. In this regard, inflammation can drive the selection and enrichment of these pathogenic communities by providing a source of nutrients in the form of tissue breakdown products (e.g. degraded collagen peptides and heme-containing compounds). In contrast, those species that cannot benefit from the altered ecological conditions of the inflammatory environment, or for which host inflammation is detrimental, are likely to be outcompeted. Consistent with the concept that inflammation fosters the growth of dysbiotic microbial communities, the bacterial biomass of human periodontitis-associated biofilms was shown to increase with increasing periodontal inflammation. Conversely, anti-inflammatory treatments in animal models of periodontitis were shown to diminish the periodontal bacterial load, in addition to protecting from bone loss. The selective flourishing of inflammophilic bacteria can perpetuate inflammatory tissue destruction by setting off a 'vicious cycle' for disease progression, in which dysbiosis and inflammation reinforce each other. Therefore, the control of inflammation appears to be central to the treatment of periodontitis, as it is likely to control both dysbiosis and disease progression.

Host modulation therapy: An indispensable part of perioceutics

Traditionally, only antimicrobials have been used as the chemotherapeutic modality for the treatment of periodontitis. Though bacteria are the primary etiologic factors of periodontal diseases, yet the extent and severity of tissue destruction seen in periodontitis is determined by the host immuno-inflammatory response to these bacteria. This increasing awareness and knowledge of the host-microbial interaction in periodontal pathogenesis has presented the opportunity for exploring new therapeutic strategies for periodontitis by means of targeting host response via host-modulating agents. This has lead to the emergence of the field of "Perioceutics" i.e. the use of parmacotherapeutic agents including antimicrobial therapy as well as host modulatory therapy for the management of periodontitis. These host-modulating agents used as an adjunct tip the balance between periodontal health and disease progression in the direction of a healing response. In this article the host-modulating role of various systemically and locally delivered perioceutic agents will be reviewed.

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

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

mRNA expression of pattern recognition receptors and their signaling mediators in healthy and diseased gingival tissues

Background:

Gingivitis and periodontitis are initiated by inflammation caused by microorganisms. Pathogen-associated molecular patterns (PAMPs) from these microorganisms are recognized through various toll-like receptors (TLRs) and NOD-like receptors (NLRs). In this study, we have chosen five TLRs and two NLRs as representatives taking part in the recognition and inflammation process, along with a few of their signaling mediators including CD14, MYD88, and TRIF to compare their mRNA expression levels between healthy and diseased gingival tissues. This will provide deeper insight into the mechanisms underlying gingivitis and periodontitis. Understanding the mechanisms involved in the onset and progression of the periodontal diseases could greatly help in establishing effective ways for prevention and treatment of these diseases besides decreasing the risk factor for relevant systemic disorders.

Materials and Methods:

Gingival tissue samples for mRNA extraction and cDNA synthesis were taken from patients with gingivitis and periodontitis and from healthy control subjects. Messenger RNA expression of all genes was assessed using real-time polymerase chain reaction (PCR).

Results:

Among the genes studied in different groups, only MYD88 mRNA expression was significantly higher in the periodontitis group compared to that of the controls. The expression level of this molecule was also significantly higher in patients with severe periodontitis compared to other patients and also compared to healthy individuals. In different tissues, positive significant correlations were observed between the mRNA expression levels of some genes.

Conclusions:

Elevated mRNA levels of MYD88 in periodontitis might have a key role in the pathogenesis of this disease. Therefore, MYD88 may be a useful target for the therapy of this disease.

Future prospects of systemic host modulatory agents in periodontal therapy

Periodontitis is an inflammatory disease caused by microbial infection that leads to destruction of supporting tissues of the teeth. The periodontal tissue destruction is a result of both microbial activity as well as host response. The best chance for clinical improvement may come from implementing complementary treatment strategies that target different aspects of the periodontal balance. Host response modulation, in combination with conventional treatment, offers to restore the balance between health and disease progression in the direction of a healing response. Various host modulatory therapies (HMT) have been developed or proposed to block pathways responsible for periodontal tissue break down. The newer drugs like bortezomib, infliximb, etanercept, vasoactive intestinal peptide, nitric oxide synthase inhibitors and denosumab are developed as a result of better understanding of pathogenesis of inflammatory tissue destruction and may represent the future of periodontal therapy. This review article focuses on the potential systemic host modulatory agents that target cell signalling pathways, cytokines and enzymes.

Phototargeting human periodontal pathogens in vivo

The effects of blue light at 455 nm were investigated on the bacterial composition of human dental plaque in vivo. Eleven subjects who refrained from brushing for 3 days before and during phototherapy participated in the study. Light with a power density of 70 mW/cm(2) was applied to the buccal surfaces of premolar and molar teeth on one side of the mouth twice daily for 2 min over a period of 4 days. Dental plaque was harvested at baseline and again at the end of 4 days from eight posterior teeth on both the exposed side and unexposed sides of the mouth. Microbiological changes were monitored by checkerboard DNA probe analysis of 40 periodontal bacteria. The proportions of black-pigmented species Porphyromonas gingivalis and Prevotella intermedia were significantly reduced on the exposed side from their original proportions by 25 and 56 %, respectively, while no change was observed to the unexposed side. Five other species showed the greatest proportional reduction of the light-exposed side relative to the unexposed side. These species were Streptococcus intermedius, Fusobacterium nucleatum ss. vincentii, Fusobacterium nucleatum ss. polymorphum, Fusobacterium periodonticum, and Capnocytophaga sputigena. At the same time, the percentage of gingival areas scored as being red decreased on the side exposed to light from 48 to 42 %, whereas the percentage scored as red increased on the unexposed side from 53 to 56 %. No adverse effects were found or reported in this study. The present study proposes a new method to modify the ecosystem in dental plaque by phototherapy and introduces a new avenue of prophylactic treatment for periodontal diseases.

Salivary visfatin concentrations in patients with chronic periodontitis

BACKGROUND

Visfatin, also known as pre-B-cell colony-enhancing factor, is secreted from a variety of cells and is thought to have some proinflammatory and immunomodulating effects. It is indicated that serum/plasma levels of visfatin increase in a number of inflammatory disorders. The present study aims to evaluate salivary concentrations of visfatin in patients with chronic periodontitis (CP).

METHODS

Twenty patients with CP and 20 periodontally healthy individuals were enrolled in this study. For each patient, the values of clinical parameters, such as bleeding index, plaque index, probing depth, and clinical attachment level (CAL), were recorded. Whole saliva samples were collected, and concentrations of visfatin were evaluated using standard enzyme-linked immunosorbent assay. Statistical analysis was performed using statistical software.

RESULTS

Visfatin was detectable in all samples. Salivary visfatin concentrations were significantly higher in the periodontitis group. In addition, there was a positive significant relationship between salivary visfatin concentrations and CAL in the periodontitis group. However, no significant association was observed between salivary visfatin levels and other periodontal parameters or body mass index.

CONCLUSION

These results indicate that there is a relationship between salivary visfatin and CP; however, further studies are needed to confirm this finding.

Atorvastatin decreases bone loss, inflammation and oxidative stress in experimental periodontitis

The aim of this study is to determine the effects of Atorvastatin treatment, an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, in periodontal disease. Male Wistar albino rats were randomly divided into five groups of ten rats each: (1) non-ligated treatment (NL), (2) ligature only (L), (3) ligature plus 1 mg/kg Atorvastatin daily for 10 days, (4) ligature plus 5 mg/kg Atorvastatin daily for 10 days, and (5) ligature plus 10 mg/kg Atorvastatin daily for 10 days. Following the treatment course, the periodontal tissue of the animals was analyzed by Measurement of alveolar bone loss, Histopathology and immunohistochemistry to determine of the expression of COX-2, MMP-2, MMP9, and RANKL/RANK/OPG. ELISA assay was used to quantitate the levels of IL-1β, IL-10, TNF-α, myeloperoxidase, malondialdehyde, and glutathione. The periodontal group treated with 10 mg/kg of Atorvastatin (3.9±0.9 mm; p<0.05) showed reverse the alveolar bone loss caused Experimental Periodontal Disease compared to (L) (7.02±0.17 mm). The periodontal group treated with 10 mg/kg of Atorvastatin showed a significant reduction in MPO and MDA (p<0.05) compared to ligature only group (L). Similarly in this group, the levels of the proinflammatory cytokines IL-1β and TNF-α were significantly decreased (p<0.05). Furthermore, MMP-2, MMP-9, RANKL/RANK, and COX-2 were all downregulated by Atorvastatin treatment, while OPG expression was increased. The findings support a role of Atorvastatin for reducing the bone loss, inflammatory response, oxidative stress, and expression of extracellular matrix proteins, while reducing RANK/RANKL and increase OPG in periodontal disease.

Thermo‐Reversible Green Tea Catechin Gel for Local Application in Chronic Periodontitis: A 4‐Week Clinical Trial

Background: Green tea extract is a naturally occurring antimicrobial agent, consisting of polyphenols (catechin) with anticariogenic, anti‐inflammatory, anticollagenolytic properties. Hence, in the present study, an attempt was made to develop a thermo‐reversible sustained‐release green tea gel and to study its clinical effects on patients with chronic periodontitis (CP).

Methods: Thermo‐reversible sustained‐release green tea catechin gel was prepared and tested for its in vitro release characteristics. An in vivo controlled, randomized, split‐mouth single‐evaluator masked study was conducted. Thirty patients with two sites in the contralateral quadrants having probing depths (PDs) of ≥4 mm were selected. Assessment of gingival index (GI), PD, and relative clinical attachment levels (rCALs) was done at baseline and at 4 weeks. Green tea and placebo gels were placed at test and control sites as an adjunct to Phase 1 periodontal therapy.

Results: Comparison of the mean ± SD GI, PD, and rCAL values within the test group at baseline (1.92 ± 0.24, 4.93 ± 0.58, and 9.97 ± 0.72, respectively) and the end of 4 weeks (0.01 ± 0.04, 2.87 ± 0.51, and 7.87 ± 0.51, respectively) showed high statistical significance (P <0.001). Comparison of mean ± SD of GI, PD, and rCAL within the control group at baseline (1.95 ± 0.16, 4.77 ± 0.50, and 9.73 ± 0.45, respectively) and the end of 4 weeks (0.16 ± 0.11, 3.8 ± 0.48, and 8.76 ± 0.43, respectively) showed significance with P <0.001. High significance was observed between the delta of measurements (0 to 4 weeks) of GI, PD, and rCAL between test (1.91 ± 0.20, 2.06 ± 0.07, and 2.1 ± 0.21, respectively) and control (1.79 ± 0.05, 0.97 ± 0.02, and 0.97 ± 0.02, respectively) groups.

Conclusion: Adjunctive local drug therapy with thermo‐reversible green tea gel has shown to reduce pockets and inflammation during the 4 weeks of the clinical trial in patients with CP.

Green tea extract as a local drug therapy on periodontitis patients with diabetes mellitus: A randomized case-control study

Background:

The green tea extract is a naturally occurring product having beneficial effects that counteract with the pathobiological features of periodontitis and diabetes mellitus. Hence, the present study was aimed at incorporation of green tea extract into hydroxylpropyl methylcellulose and investigates its efficacy in chronic periodontitis patients associated with and without diabetes mellitus.

Materials and Methods:

For the in vitro study, formulation of green tea strips and placebo strips, and analysis of drug release pattern from the green tea strips at different time intervals were performed. For the in vivo study, 50 patients (20-65 years), including 25 systemically healthy patients with chronic periodontitis (group 1) and 25 diabetic patients with chronic periodontitis (group 2) were enrolled. In each patient, test and control sites were identified for the placement of green tea and placebo strips, respectively. Gingival Index (GI), Probing Pocket Depth (PPD), and Clinical Attachment Level (CAL) were examined at baseline, first, second, third, and fourth weeks. Microbiological analysis for Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans was performed at baseline and fourth week.

Results:

The in vitro study showed 10.67% green tea release at 30 min; thereafter, a slow release was noted till 120 min.

In vivo study:

Both groups showed significant reduction in GI scores at the test sites. Group 1 showed significant (P < 0.001) PPD reduction at different time intervals at the test sites. However, group 2 showed significant reduction from baseline (5.30 ± 0.70) to fourth week (3.5 ± 0.97). Statistically significant gain in CAL at the test sites was observed both in group 1 (1.33 mm) and group 2 (1.43 mm). The prevalence of P. gingivalis in group 1 test sites was significantly reduced from baseline (75%) to fourth week (25%).

Conclusions:

Local drug delivery using green tea extract could be used as an adjunct in the treatment of chronic periodontitis in diabetic and non-diabetic individuals.

Differential expression of mitogen activating protein kinases in periodontitis

AIM

Following toll-like receptor (TLR) engagement, lipopolysaccharide (LPS) can stimulate the expression of pro-inflammatory cytokines thus activating the innate immune response. The production of inflammatory cytokines results, in part, from the activation of kinase-induced signalling cascades and transcriptional factors. Of the four distinct classes of mitogen-activated protein kinases (MAPK) described in mammals, p38, c-Jun N-terminal activated kinases (JNK1-3) and extracellular activated kinases (ERK1,2) are the best studied. Previous data have established that p38 MAPK signalling is required for inflammation and bone loss in periodontal disease pre-clinical animal models.

MATERIALS & METHODS

In this study, we obtained healthy and diseased periodontal tissues along with clinical parameters and microbiological parameters. Excised fixed tissues were immunostained with total and phospho-specific antibodies against p38, JNK and ERK kinases.

RESULTS

Intensity scoring from immunostained tissues was correlated with clinical periodontal parameters. Rank correlations with clinical indices were statistically significantly positive (p-value < 0.05) for total p38 (correlations ranging 0.49-0.68), phospho-p38 (range 0.44-0.56), and total ERK (range 0.52-0.59) levels, and correlations with JNK levels also supported association (range 0.42-0.59). Phospho-JNK and phospho-ERK showed no significant positive correlation with clinical parameters of disease.

CONCLUSION

These data strongly implicate p38 MAPK as a major MAPK involved in human periodontal inflammation and severity.

Role of salivary epithelial toll-like receptors 2 and 4 in modulating innate immune responses in chronic periodontitis

BACKGROUND AND OBJECTIVE

Chronic periodontitis is initiated by sequential colonization with a broad array of bacteria and is perpetuated by an immune-inflammatory response to the changing biofilm. Host recognition of microbes is largely mediated by toll-like receptors (TLRs), which interact with conserved pathogen-associated molecular patterns. Based on ligand recognition, TLR-2 and TLR-4 interact with most periodontal pathogens. Extracrevicular bacterial reservoirs, such as the oral epithelial cells, contribute to the persistence of periodontitis. Human saliva is a rich source of oral epithelial cells that express functional TLRs. In this study we investigated the role of salivary epithelial cell (SEC) TLR-2 and TLR-4 in patients with generalized chronic periodontitis.

MATERIAL AND METHODS

Unstimulated whole saliva (UWS) was collected from patients with generalized chronic periodontitis and from healthy individuals after obtaining informed consent. Epithelial cells isolated from each UWS sample were assessed for TLR-2, TLR-4, peptidoglycan recognition protein (PGRP)-3 and PGRP-4 by quantitative real-time PCR. In addition, the SECs were stimulated in vitro with microbial products for up to 24 h. The culture supernatant was assessed for cytokines by ELISA.

RESULTS

Stimulation with TLR-2- or TLR-4-specific ligands induced cytokine secretion with differential kinetics and up-regulated TLR2 and TLR4 mRNAs, respectively, in cultures of SECs from patients with periodontitis. In addition, the SECs from patients with periodontitis exhibited reduced PGRP3 and PGRP4 mRNAs, the TLR-responsive genes with antibacterial properties.

CONCLUSION

SECs derived from the UWS of patients with chronic periodontitis are phenotypically distinct and could represent potential resources for assessing the epithelial responses to periodontal pathogens in the course of disease progression and persistence.

Curcumin inhibits inflammatory response and bone loss during experimental periodontitis in rats

OBJECTIVE

Curcumin, an active ingredient of turmeric, is proved to be a potential candidate of controlling inflammation and bone resorption, but few reports are on the periodontitis. The purpose of this study was to evaluate whether the intra-gastric administration of curcumin could inhibit the inflammation and alveolar bone resorption in rats following ligature-induced experimental periodontitis.

MATERIALS AND METHOD

Male Wistar rats were randomly divided into three groups: no ligature placement and administration of vehicle, ligature placement and administration of vehicle, ligature placement and administration of curcumin. After the animals were sacrificed, their mandibles were collected for morphological, histological and immunohistochemical analysis; their gingival tissues were collected for cytokine measurements.

RESULTS

Bone resorption was significantly higher in the experimental periodontitis animals treated with vehicle compared with the curcumin-treated group or the control group. Furthermore, receptor activator of nuclear factor-κB ligand (RANKL), receptor activator of nuclear factor-κB (RANK), osteoprotegerin (OPG), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) expression levels were higher in the experimental periodontitis animals treated with vehicle compared with the curcumin treated group or the control group. CONCLUSIONS. Curcumin may decrease alveolar bone loss in the experimental periodontitis rats via suppressing the expression of RANKL/RANK/OPG and its anti-inflammatory properties.

Efficacy of subantimicrobial-dose doxycycline against nitrosative stress in chronic periodontitis

AIM

To evaluate the effectiveness of subantimicrobial-dose doxycycline (SDD) as an adjunct to scaling and root planing (SRP) treatment against the nitrosative stress of moderate to advanced chronic periodontitis.

METHODS

Adults with untreated chronic periodontitis (n=174) were randomly administered SRP+SDD (n=87) (20 mg of doxycycline twice daily) or SRP+placebo (n=87) treatment for 3 months. At baseline and after 3 months, the probing depths (PD), bleeding on probing (BOP) and clinical attachment level (CAL) were measured, and a gingivomucosal biopsy was collected to assay the induction of nitric oxide synthase (iNOS) and 3-nitrotyrosine (3NT), and blood was collected to assay for total nitrites and nitrates (NO(x)) and 3NT.

RESULTS

Compared to baseline, at the completion of treatment, significant decreases in the levels of tissue iNOS and 3NT and serum NO(x) and 3NT were observed in both groups. SRP+SDD yielded a greater reduction in the gingivomucosal and serum nitrosative stress markers than did SRP+placebo. PD, BOP, and CAL reduction were correlated with the nitrosative stress parameters.

CONCLUSION

On a short-term basis, SDD therapy may be used as an adjunct to SRP treatment against nitrosative stress in moderate to advanced chronic periodontitis.

A modified method for inducing periodontitis in dogs using a silk-wire twisted ligature

This study was designed to assess the effectiveness of a modified silk ligature twisted with wire for inducing advanced periodontitis. Periodontitis was induced in five premolars and one molar of 20 healthy dogs over a 60-day period. The dogs were divided into four groups according to the ligature-inducing materials used: soft moistened food only, wire ligature (WL), silk ligature (SL) and twisted ligature with silk and wire (SWL). Periodontal indices were recorded, and dental radiographs were taken before and after 60 days of ligation. The ligatures were checked daily and the day the ligature fell out was noted. The period during which the ligatures were maintained was significantly shorter for the SL group compared to the SWL group (p < 0.05). Results of the clinical examination showed that almost all periodontal status parameters including the plaque index, gingival index, clinical attachment level, and bleeding on probing were significantly exacerbated in the SWL group compared to the other groups (p < 0.05). Radiographic evaluation demonstrated that alveolar bone levels were significantly lower in the SWL group than the other groups on day 60 (p < 0.05). These results suggested that experimental periodontitis induced by SWL could be an effective method for investigating periodontitis in canine models.

Oxidative stress resistance in Porphyromonas gingivalis

Porphyromonas gingivalis, a black-pigmented, Gram-negative anaerobe, is an important etiologic agent of periodontal disease. The harsh inflammatory condition of the periodontal pocket implies that this organism has properties that will facilitate its ability to respond and adapt to oxidative stress. Because the stress response in the pathogen is a major determinant of its virulence, a comprehensive understanding of its oxidative stress resistance strategy is vital. We discuss multiple mechanisms and systems that clearly work in synergy to defend and protect P. gingivalis against oxidative damage caused by reactive oxygen species. The involvement of multiple hypothetical proteins and/or proteins of unknown function in this process may imply other unique mechanisms and potential therapeutic targets.

Treatment modalities and evaluation models for periodontitis

Periodontitis is the most common localized dental inflammatory disease related with several pathological conditions like inflammation of gums (gingivitis), degeneration of periodontal ligament, dental cementum and alveolar bone loss. In this perspective, the various preventive and treatment modalities, including oral hygiene, gingival irrigations, mechanical instrumentation, full mouth disinfection, host modulation and antimicrobial therapy, which are used either as adjunctive treatments or as stand-alone therapies in the non-surgical management of periodontal infections, have been discussed. Intra-pocket, sustained release systems have emerged as a novel paradigm for the future research. In this article, special consideration is given to different locally delivered anti-microbial and anti inflammatory medications which are either commercially available or are currently under consideration for Food and Drug Administration (FDA) approval. The various in vitro dissolution models and microbiological strain investigated to impersonate the infected and inflamed periodontal cavity and to predict the in vivo performance of treatment modalities have also been thrashed out. Animal models that have been employed to explore the pathology at the different stages of periodontitis and to evaluate its treatment modalities are enlightened in this proposed review.

Aggregatibacter actinomycetemcomitans infection enhances apoptosis in vivo through a caspase-3-dependent mechanism in experimental periodontitis

The purpose of this study was to test the hypothesis that diabetes aggravates periodontal destruction induced by Aggregatibacter actinomycetemcomitans infection. Thirty-eight diabetic and 33 normal rats were inoculated with A. actinomycetemcomitans and euthanized at baseline and at 4, 5, and 6 weeks after inoculation. Bone loss and the infiltration of polymorphonuclear leukocytes (PMNs) in gingival epithelium were measured in hematoxylin-eosin-stained sections. The induction of tumor necrosis factor alpha (TNF-α) was evaluated by immunohistochemistry and of apoptotic cells by a TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling) assay. After A. actinomycetemcomitans infection, the bone loss in diabetic rats was 1.7-fold and the PMN infiltration 1.6-fold higher than in normoglycemic rats (P < 0.05). The induction of TNF-α was 1.5-fold higher and of apoptotic cells was up to 3-fold higher in diabetic versus normoglycemic rats (P < 0.05). Treatment with a caspase-3 inhibitor significantly blocked noninflammatory cell apoptosis induced by A. actinomycetemcomitans infection in gingival epithelium and connective tissue (P < 0.05). These results provide new insight into how diabetes aggravates A. actinomycetemcomitans-induced periodontal destruction in rats by significantly increasing the inflammatory response, leading to increased bone loss and enhancing apoptosis of gingival epithelial and connective tissue cells through a caspase-3-dependent mechanism. Antibiotics had a more pronounced effect on many of these parameters in diabetic than in normoglycemic rats, suggesting a deficiency in the capacity of diabetic animals to resist infection.

Therapeutic strategies in the treatment of periodontitis

Periodontitis is a chronic inflammatory process which affects the tooth - supporting structures of the teeth. The disease is initiated by subgingival periopathogenic bacteria in susceptible periodontal sites. The host immune response towards periodontal pathogens helps to sustain periodontal disease and eventual alveolar bone loss. Although scaling and root planing is the standard treatment modality for periodontitis, it suffers from several drawbacks such as the inability to reach the base of deep pockets and doesn’t arrest migration of periodontal pathogens from other sites in the oral cavity. In order to overcome the limitations of scaling and root planning, adjunctive chemotherapeutics and host modulatory agents to the treatment are used. These therapeutic agents show substantial beneficial effects when compared to scaling and root planning alone. This review will cover an update on chemotherapeutic and past and future host immune modulatory agents used adjunctively to treat and manage periodontal diseases.

MAPK usage in periodontal disease progression

In periodontal disease, host recognition of bacterial constituents, including lipopolysaccharide (LPS), induces p38 MAPK activation and subsequent inflammatory cytokine expression, favoring osteoclastogenesis and increased net bone resorption in the local periodontal environment. In this paper, we discuss evidence that the p38/MAPK-activated protein kinase-2 (MK2) signaling axis is needed for periodontal disease progression: an orally administered p38α inhibitor reduced the progression of experimental periodontal bone loss by reducing inflammation and cytokine expression. Subsequently, the significance of p38 signaling was confirmed with RNA interference to attenuate MK2-reduced cytokine expression and LPS-induced alveolar bone loss. MAPK phosphatase-1 (MKP-1), a negative regulator of MAPK activation, was also critical for periodontal disease progression. In MPK-1-deficient mice, p38-sustained activation increased osteoclast formation and bone loss, whereas MKP-1 overexpression dampened p38 signaling and subsequent cytokine expression. Finally, overexpression of the p38/MK2 target RNA-binding tristetraprolin (TTP) decreased mRNA stability of key inflammatory cytokines at the posttranscriptional level, thereby protecting against periodontal inflammation. Collectively, these studies highlight the importance of p38 MAPK signaling in immune cytokine production and periodontal disease progression.