Curcumin modulates the immune response associated with LPS-induced periodontal disease in rats

Herbal and nano-based herbal medicine: New insights into their therapeutic aspects against periodontitis

Objective

Periodontitis is a type of prevalent chronic inflammatory disorder resulting in a failure in the function of tissues supporting the tooth, like gingiva, alveolar bone, and periodontal ligament. Although antibiotic therapy is a common therapy for periodontitis cases, this approach can cause some adverse effects in these patients. Thus, finding an effective curative option with low side effects is still a puzzle.

Materials and Methods

This narrative review was conducted on the effects of herbal and nano-based herbal medicine against periodontitis by searching different databases such as Google Scholar, PubMed, Scopus, Web of Science, Science Direct, and Scientific Information Databases.

Results

According to published studies, some popular herbal formulations, such as Aloe vera, curcumin, Melaleuca alternifolia, and Scutellaria baicalensis Georgi, can be effective in periodontitis treatment. However, these herbal products may be accompanied by some pharmacological limitations, such as poor bioavailability, instability, and weak water solubility. On the other hand, harnessing nano-based herbal formulations can elevate the bioavailability, diminish toxicity, and omit repeated administration of drugs.

Conclusion

Herbal and nano-based herbal products can create a good chance to treat periodontitis efficiently.

Computational analysis of curcumin-mediated alleviation of inflammation in periodontitis patients with experimental validation in mice

AIM

Using network pharmacology and experimental validation to explore the therapeutic efficacy and mechanism of curcumin (Cur) in periodontitis treatment.

MATERIALS AND METHODS

Network pharmacology was utilized to predict target gene interactions of Cur-Periodontitis. Molecular docking was used to investigate the binding affinity of Cur for the predicted targets. A mouse model with ligature-induced periodontitis (LIP) was used to verify the therapeutic effect of Cur. Microcomputed tomography (micro-CT) was used to evaluate alveolar bone resorption, while western blotting, haematoxylin-eosin staining and immunohistochemistry were used to analyse the change in immunopathology. SYTOX Green staining was used to assess the in vitro effect of Cur in a mouse bone marrow-isolated neutrophil model exposed to lipopolysaccharide.

RESULTS

Network pharmacology identified 114 potential target genes. Enrichment analysis showed that Cur can modulate the production of neutrophil extracellular traps (NETs). Molecular docking experiments suggested that Cur effectively binds to neutrophil elastase (ELANE), peptidylarginine deiminase 4 (PAD4) and cathepsin G, three enzymes involved in NETs. In LIP mice, Cur alleviated alveolar bone resorption and reduced the expression of ELANE and PAD4 in a time-dependent but dose-independent manner. Cur can directly inhibit NET formation in the cell model.

CONCLUSIONS

Our research suggested that Cur may alleviate experimental periodontitis by inhibiting NET formation.

"Medicine food homology" plants promote periodontal health: antimicrobial, anti-inflammatory, and inhibition of bone resorption

"Medicine food homology" (MFH) is a term with a lengthy history. It refers to the fact that a lot of traditional natural products have both culinary and therapeutic benefits. The antibacterial, anti-inflammatory and anticancer effects of MFH plants and their secondary metabolites have been confirmed by numerous research. A bacterially generated inflammatory illness with a complicated pathophysiology, periodontitis causes the loss of the teeth's supporting tissues. Several MFH plants have recently been shown to have the ability to prevent and treat periodontitis, which is exhibited by blocking the disease's pathogens and the virulence factors that go along with them, lowering the host's inflammatory reactions and halting the loss of alveolar bone. To give a theoretical foundation for the creation of functional foods, oral care products and adjuvant therapies, this review has especially explored the potential medicinal benefit of MFH plants and their secondary metabolites in the prevention and treatment of periodontitis.

Impact of nutraceuticals on immunomodulation against viral infections-A review during COVID-19 pandemic in Indian scenario

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) originated in Wuhan, China, in early December 2019 is a censorious global emergency after World War II. Research on the coronavirus uncovered essential information that aided in the development of the vaccine, and specific coronavirus disease 2019 (COVID-19) vaccines were later developed and were approved for usage in humans. But then, mutations in the coronavirus gave rise to new variants and questioned the vaccine's efficacy against them. On the other hand, the investigation of traditional medicine was also on its path to find a novel outcome against COVID-19. On a comparative analysis between India and the United States, India had low death rate and high recovery rate than the latter. The dietary regulation of immunity may be the factor that makes the above difference. The immunity gained from the regular diet of Indian culture nourishes Indian people with essential phytochemicals that support immunity and metabolism. Dietary phytochemicals or nutraceuticals possess antioxidant, anti-inflammatory, and anticancer properties, out of which our concern will be on immune-boosting phytochemicals from our daily nutritional supplements. In several case studies, dietary substance like lemon, ginger, and spinach was reported in the recovery of COVID-19 patients. Thus in this review, we discuss coronavirus and its available variants, vaccines, and the effect of nutraceuticals against the coronavirus. Further, we denote that the immunity of the Indian population may be high because of their diet, which adds natural phytochemicals to boost their immunity and metabolism.

Immune senescence and periodontitis: From mechanism to therapy

Periodontitis is one of the most prevalent infectious inflammatory diseases, characterized by irreversible destruction of the supporting tissues of teeth, which is correlated with a greater risk of multiple systemic diseases, thus regarded as a major health concern. Dysregulation between periodontal microbial community and host immunity is considered to be the leading cause of periodontitis. Comprehensive studies have unveiled the double-edged role of immune response in the development of periodontitis. Immune senescence, which is described as age-related alterations in immune system, including a diminished immune response to endogenous and exogenous stimuli, a decline in the efficiency of immune protection, and even failure in immunity build-up after vaccination, leads to the increased susceptibility to infection. Recently, the intimate relationship between immune senescence and periodontitis has come into focus, especially in the aging population. In this review, both periodontal immunity and immune senescence will be fully introduced, especially their roles in the pathology and progression of periodontitis. Furthermore, novel immunotherapies targeting immune senescence are presented to provide potential targets for research and clinical intervention in the future.

Therapeutic Potential of Polyphenol and Nanoparticles Mediated Delivery in Periodontal Inflammation: A Review of Current Trends and Future Perspectives

Periodontitis is an oral inflammatory process involving the periodontium, which is mainly caused by the invasion of periodontopathogenic microorganisms that results in gingival connective tissue and alveolar bone destruction. Metabolic products of the oral pathogens and the associated host immune and inflammatory responses triggered are responsible for the local tissue destruction. Numerous studies in the past decades have demonstrated that natural polyphenols are capable of modulating the host inflammatory responses by targeting multiple inflammatory components. The proposed mechanism by which polyphenolic compounds exert their great potential is by regulating the immune cell, proinflammatory cytokines synthesis and gene expression. However, due to its low absorption and bioavailability, the beneficial effects of these substances are very limited and it hampers their use as a therapeutic agent. To address these limitations, targeted delivery systems by nanoencapsulation techniques have been explored in recent years. Nanoencapsulation of polyphenolic compounds with different carriers is an efficient and promising approach to boost their bioavailability, increase the efficiency and reduce the degradability of natural polyphenols. In this review, we focus on the effects of different polyphenolic substances in periodontal inflammation and to explore the pharmaceutical significance of polyphenol-loaded nanoparticles in controlling periodontitis, which may be useful for further enhancement of their efficacy as therapeutic agents for periodontal disease.

Unravelling the Immune Modulatory Effect of Indian Spices to Impede the Transmission of COVID-19: A Promising Approach

Months after WHO declared COVID-19 as a Global Public Health Emergency of International Concern, it does not seem to be flattening the curve as we are still devoid of an effective treatment modality and vaccination is in the first phase in many countries. Amid such uncertainty, being immune is the best strategy to defend against corona attacks. As the whole world is referring back to immune-boosting traditional remedies, interest is rekindled in the Indian system of Medicine, which is gifted with an abundance of herbal medicines as well as remedies. Among them, spices (root, rhizome, seed, fruit, leaf, bud, and flower of various plants used to add taste and flavors to food) are bestowed with immense medicinal potential. A plethora of clinical as well as preclinical studies reported the effectiveness of various spices for various ailments. The potential immune-boosting properties together with their excellent safety profiles are making spices the current choice of phytoresearch as well as the immune-boosting home remedies during these sceptical times. The present review critically evaluates the immune impact of various Indian spices and their potential to tackle the novel coronavirus, with comments on the safety and toxicity aspects of spices.

Anti-Periodontitis Effect of Ethanol Extracts of Alpinia Katsumadai Seeds

Oral microbes are intimately associated with many oral and systemic diseases. Ongoing research is seeking to elucidate drugs that prevent and treat microbial diseases. Various functions of Alpinia Katsumadai seed extracts have been reported such as their anti-viral, anti-oxidant, anti-inflammatory, anti-puritic, anti-emetic, and cytoprotective effects. Here, we investigated the anti-periodontitis effect of an ethanol extract of Alpinia Katsumadai seeds (EEAKSs) on dental plaque bacteria (DPB)-induced inflammation and bone resorption. DPB and Porphyromonas gingivalis (P. gingivalis) were cultured and lipopolysaccharide (LPS) was extracted. Prostaglandin E₂ (PGE₂) and cyclooxygenase 2 (COX-2) levels were estimated using ELISA. Cytotoxicity was also verified. Proteases were screened using a protease antibody array method. Osteoclastic bone resorption was also investigated. EEAKSs suppressed P. gingivalis growth on agar plates. LPS prepared from dental plaque bacteria (DPB-LPS) and P. gingivalis (PG-LPS) significantly increased PGE₂ and COX2 levels in immortalized gingival fibroblasts (IGFs), immortalized human oral keratinocytes (IHOKs), and RAW264.7 macrophage cells. However, DPB-LPS and PG-LPS-induced PGE₂ and COX-2 increases were effectively abolished by EEAKS treatment at non-cytotoxic concentrations. In the protease antibody array, matrix metalloproteinase (MMP)-2, MMP-3, MMP-7, kallikrein 10, cathepsin D, and cathepsin V levels were increased by PG-LPS stimulation. However, increases in protease levels except for cathepsin D were suppressed by EEAKS treatment. In addition, RANKL-induced osteoclast differentiation was significantly inhibited by EEAKS treatment, leading to reductions in resorption pit formation. These results suggest that EEAKSs exerted a beneficial oral health effect to help prevent DPB-mediated periodontal disease.

Cold Atmospheric Plasma Jet as a Possible Adjuvant Therapy for Periodontal Disease

Due to the limitations of traditional periodontal therapies, and reported cold atmospheric plasma anti-inflammatory/antimicrobial activities, plasma could be an adjuvant therapy to periodontitis. Porphyromonas gingivalis was grown in blood agar. Standardized suspensions were plated on blood agar and plasma-treated for planktonic growth. For biofilm, dual-species Streptococcus gordonii + P. gingivalis biofilm grew for 48 h and then was plasma-treated. XTT assay and CFU counting were performed. Cytotoxicity was accessed immediately or after 24 h. Plasma was applied for 1, 3, 5 or 7 min. In vivo: Thirty C57BI/6 mice were subject to experimental periodontitis for 11 days. Immediately after ligature removal, animals were plasma-treated for 5 min once-Group P1 (n = 10); twice (Day 11 and 13)-Group P2 (n = 10); or not treated-Group S (n = 10). Mice were euthanized on day 15. Histological and microtomography analyses were performed. Significance level was 5%. Halo diameter increased proportionally to time of exposure contrary to CFU/mL counting. Mean/SD of fibroblasts viability did not vary among the groups. Plasma was able to inhibit P. gingivalis in planktonic culture and biofilm in a cell-safe manner. Moreover, plasma treatment in vivo, for 5 min, tends to improve periodontal tissue recovery, proportionally to the number of plasma applications.

Effects of curcumin gel on osteoclastogenic bone markers in experimental periodontitis and alveolar bone loss in wistar rats

BACKGROUND/PURPOSE

Curcumin has anti-inflammatory impacts and was suggested as an inflammatory disease therapy. This study aimed to investigate the implications of curcumin gel on experimental periodontitis (EPD) and alveolar bone loss in rats.

MATERIALS AND METHODS

In this study, twenty-four male Wistar rats were divided equally into four groups: negative control (with no EPD); positive control (EPD induced around lower centrals without treatment); control-treated group: EPD treated with chlorhexidine; and test EPD group treated with curcumin. After 30 days, the serum concentrations of RANKL and IL-1β were measured via ELISA. All animals were sacrificed, and mandibular central incisors with the periodontium were removed. The lingual probing depth and radiographical alveolar bone loss were measured, then samples processed for routine preparation of H&E stained sections and histologically assessed for counting inflammatory cells, osteoclasts, and PDL width.

RESULTS

A significant decrease in the inflammatory cells infiltration, probing depth, and osteoclast numbers with the improvement of PDL associated with a reduction in RANKL and IL-1β serum concentration were seen in both EPD treated groups.

CONCLUSION

Curcumin is as effective as chlorhexidine in treating experimental periodontitis in rats. It was demonstrated to stop bone destruction related to periodontitis by regulating the RANKL and IL-1β markers level in the blood.

Curcumin: A review of experimental studies and mechanisms related to periodontitis treatment

Curcumin is the main active ingredient of turmeric, which has a wide range of pharmacological effects, including antitumor, antibacterial, anti-inflammatory, anti-oxidation, immune regulation, and so on. Periodontitis is a prevalent oral inflammatory disease caused by a variety of factors. In recent years, many studies have shown that curcumin has a potential role on the treatment of periodontitis. Curcumin has been used in research related to the treatment of periodontitis in the form of solution, chip, gel, and capsule. Combined with other periodontitis treatment methods, such as scaling and root planing (SRP) and photodynamic therapy (PDT), can enhance curcumin's efficacy in treating periodontitis. In addition to natural curcumin, chemically modified curcumin, such as 4-phenylaminocarbonyl bis-demethoxy curcumin (CMC 2.24) and 4-methoxycarbonyl curcumin (CMC 2.5), have also been used in animal models of periodontitis. Here, this paper reviews the research progress of curcumin on the treatment of periodontitis and its related mechanisms.

Can an anti-inflammatory diet be effective in preventing or treating viral respiratory diseases? A systematic narrative review

Respiratory Viruses infections (RVI) such as rhinovirus, coronavirus, influenza virus, and adenovirus affect the respiratory and the immune systems. The role of nutrition in the respiratory and immune systems has been studied in some studies, and its importance is undeniable. In addition, one of the key findings in this disease is high inflammation that affects almost all patients. This systematic narrative review aims to answer the question, "Can an anti-inflammatory diet be effective in preventing or treating viral respiratory diseases?" A systematic review search was used for the articles extraction. All studies published in English from 1999 to 2020 investigating dietary inflammatory conditions and RVI were included. Food items with anti-inflammatory properties were selected based on the definition of the dietary inflammatory index (DII). We used Google Scholar, Pub Med, Scopus, Web of Science, Springer, Science Direct, Directory of Open Access Journals, Elsevier, Taylor and Francis, ProQuest, EBSCO, MEDLINE, and SciELO databases for extracting articles. Keywords were restricted by DII. Based on DII, food items/nutrients are involved in inflammation, some of which have anti-inflammatory and some inflammatory properties. Some foods/nutrients, in addition to their anti-inflammatory properties, have antioxidant, antiviral, and immune-enhancing properties. Considering the immune system's involvement, increased inflammation, and involvement of the pulmonary system in RVI and the remarkable role of the anti-inflammatory foods for counteracting them, it is recommended to use a predominantly anti-inflammatory diet along with prevention/control and treatment protocols. An anti-inflammatory diet (based on DII) includes turmeric, ginger, garlic, onions, saffron, dietary vitamin C, vitamin D, zinc, and omega-3 are recommended to reduce infection symptoms and duration.

From Simple Mouth Cavities to Complex Oral Mucosal Disorders-Curcuminoids as a Promising Therapeutic Approach

Oral diseases are among the most common encountered health issues worldwide, which are usually associated with anomalies of the oral cavity, jaws, and salivary glands. Despite the availability of numerous treatment modalities for oral disorders, a limited clinical response has been observed because of the inefficacy of the drugs and countless adverse side effects. Therefore, the development of safe, efficacious, and wide-spectrum therapeutics is imperative in the battle against oral diseases. Curcumin, extracted from the golden spice turmeric, is a well-known natural polyphenol that has been extensively studied for its broad pleiotropic attributes and its ability to modulate multiple biological processes. It is well-documented to target pro-inflammatory mediators like NF-κB, ROS, COX-2, IL-1, IL-2, TGF-β, growth factors, apoptotic proteins, receptors, and various kinases. These properties make curcumin a promising nutraceutical in the treatment of many oral diseases like oral submucous fibrosis, oral mucositis, oral leukoplakia, oral erythroplakia, oral candidiasis, aphthous stomatitis, oral lichen planus, dental caries, periodontitis, and gingivitis. Numerous in vitro and in vivo studies have shown that curcumin alleviates the symptoms of most of the oral complications, including the inhibition of the progression of oral cancer. In this regard, many clinical trials have been completed, and many are ongoing to investigate the "curcumin effect" in oral maladies. Therefore, the current review delineates the mechanistic framework of curcumin's propensity in curbing oral diseases and present outcomes of the clinical trials of curcumin-based therapeutics that can provide a breakthrough in the clinical management of these diseases.

Chalcone T4, a novel chalconic compound, inhibits inflammatory bone resorption in vivo and suppresses osteoclastogenesis in vitro

OBJECTIVE

This study aimed to assess the effect of a novel synthetic chalcone, Chalcone T4, on a murine model of periodontitis and on RANKL-induced osteoclastogenesis in vitro.

BACKGROUND

Chalcones are natural compounds with anti-inflammatory properties, and its synthetic analogs with enhanced biological effects have potential as therapeutic agents. Periodontitis is characterized by chronic inflammation of the periodontium and alveolar bone resorption. Safe and effective anti-inflammatory agents can have an important additive effect in the treatment in this disease.

METHODS

Periodontitis was induced via the installation of a ligature around the first molar. Rats (n = 32) received Chalcone T4 (5 and 50 mg/kg) or distilled water by gavage daily for 15 days. Outcomes assessed were bone resorption (μCT), TNF-α production (ELISA), cellular infiltrate, and collagen content (stereometric analysis, CD45+ cells by immunohistochemistry), and activation of NFATc1 and NF-kB (immunohistochemistry). In vitro, RAW 264.7 were treated with Chalcone T4 and stimulated with RANKL for assessment of osteoclast differentiation (actin ring staining) and activity (pit assay).

RESULTS

Chalcone T4 significantly reduced periodontitis-associated bone resorption, as well as the cellular infiltrate, while increasing the collagen content. Production of TNF-α, infiltration of CD45-positive cells, and NF-kB activation were markedly reduced. In vitro, chalcone T4 inhibited both osteoclast differentiation and activity.

CONCLUSION

Chalcone T4 significantly inhibited alveolar bone resorption and inflammation in vivo and RANKL-induced osteoclastogenesis in vitro, suggesting a therapeutic role for this compound in the treatment of periodontitis.

Leukotriene receptor antagonist reduces inflammation and alveolar bone loss in a rat model of experimental periodontitis

BACKGROUND

Leukotrienes (LTs) participate in the process of tissue damage in periodontal disease by leukocyte chemotaxis and osteoclastic activation. The activation of Cysteinyl-LT receptor is associated with increased expression of proinflammatory molecules and osteoclastogenesis. However, its implications on periodontal disease progression have not been studied. The present study evaluated the effect of the cysteinyl-LT receptor antagonist (montelukast [MT]) on ligature-induced experimental periodontitis (EP) in rats.

METHODS

Adult male Wistar rats were subjected to bilateral ligature-induced periodontitis and orally treated with MT (at doses of 10 or 30 mg/kg/d, MT10, and MT30, respectively). Sham animals had the ligatures immediately removed and received placebo treatment. Sets of animals were euthanized 7, 14, or 21 days after ligature placement and the mandibles were removed for macroscopic evaluation of alveolar bone loss (ABL). In addition, histological analysis of periodontal tissues, myeloperoxidase (MPO) activity of gingival tissues, and periodontal tissue expression of collagen type I, RUNX2, RANK, RANKL, OPG, BLT1, Cys-LTR1, LTA4H, and LTC4S were also analyzed.

RESULTS

MT significantly reduced ABL at 14 (MT10 and MT30) and 21 days (MT10) (P < 0.05), gingival MPO at 7 (MT10) and 14 days (MT30) (P < 0.05), LTA4H, BLT1 and LTC4S gene expression on day 14 day (MT30, P < 0.05) and increased RUNX2 expression on day 14 (MT30, P < 0.05).

CONCLUSION

Systemic therapy with MT decreases periodontal inflammation and ABL in ligature-induced periodontitis in rats.

Impact of citrus flavonoid supplementation on inflammation in lipopolysaccharide-induced periodontal disease in mice

In general, the consumption of flavonoid-rich foods may influence the control/dysregulation of the magnitude and duration of inflammation and oxidative stress, which are known to contribute to multiple pathologies. Information regarding the impact of citrus flavonoid dietary supplementation on periodontal disease is still scarce. Herein, we investigated whether a diet supplemented with eriocitrin and eriodictyol could alter the course of the inflammatory response associated with LPS-induced periodontal disease in mice. Sixty BALB/c mice received a standard diet or a diet supplemented with different concentrations of eriocitrin or eriodictyol. After 30 days of food supplementation, a solution containing LPS from Escherichia coli was injected into the gingival tissues three times per week for four weeks. Neutrophils, mononuclear cells and eosinophils were assessed using a severity analysis system in H&E-stained sections and modified picrosirius red. The activities of myeloperoxidase (MPO), a marker of granulocyte infiltration, and eosinophil peroxidase (EPO) were determined spectrophotometrically. The oxidative damage was determined by measuring the malondialdehyde (MDA) content and anti-oxidative activity through the assessment of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Interleukin (IL)-1β, TNF-α, and IL-10 were quantified by multiplex immunoassay. Periodontal inflammation was significantly inhibited by citrus flavonoid supplementation, including reduced flatness of the gingival epithelium and chronic and acute inflammatory cell infiltration, as well as loss of connective tissue in the gingival papillae. Both eriocitrin and eriodictyol inhibited gingival IL-1β and TNF-α and increased IL-10 secondary to periodontitis. Significant protection and decreased MPO and EPO activity were detected in the periodontal tissue of citrus flavonoid-treated animals. In comparison with the LPS group, SOD, CAT and GPx activities were increased, while the MDA content was reduced, indicating decreased oxidative damage. These results suggest that a diet supplemented with the citrus flavonoids eriocitrin or eriodictyol may aid in the prevention of periodontitis, representing a potential method to enhance local immunity and host defense.

Silencing matrix metalloproteinase-13 (Mmp-13) reduces inflammatory bone resorption associated with LPS-induced periodontal disease in vivo

OBJECTIVES

The aim of this study was to evaluate the effect of specific inhibition of MMP-13 on inflammation and inflammatory bone resorption in a murine model of lipopolysaccharide (LPS)-induced periodontitis.

MATERIALS AND METHODS

Periodontitis was induced in mice by micro-injections of LPS into the gingival tissues adjacent to the palatal surfaces of maxillary molars twice a week for 15 days. Matrix metalloproteinase-13 (Mmp-13) shRNA or a specific biochemical inhibitor were also injected into the same sites in alternating days with the LPS injections. Efficacy of shRNA-mediated silencing of Mmp-13 was verified by quantitative real-time polymerase chain reaction (qPCR) and immunoblot. Bone resorption was assessed by microcomputed tomography (uCT). Histological sections stained with hematoxylin/eosin (H/E) were used in the stereometric analysis of the inflammatory infiltrate. Gingival tissues were used to evaluate expression of Mmp-13, Il-6, Tnf-α, Ptgs2, and Rankl (qPCR). Protein levels of TGF-β and IL-10 in the tissues were determined by enzyme-linked immunosorbent assays (ELISA) or by MMP-13 and p38 immunoblot.

RESULTS

Silencing Mmp-13 expression reduced bone resorption significantly. Expression of Mmp-13, Il-6, and Tnf-α, as well as the protein levels of IL-6 and TNF-α, was reduced in the animals treated with adenovirus-delivered shRNA; however, these effects were not associated with modulation of p38 MAPK signaling. Interestingly, inhibition Mmp-13 did not affect the severity of inflammatory infiltrate.

CONCLUSIONS

Site-specific inhibition of MMP-13 reduced bone resorption and production of inflammatory mediators associated with periodontal disease.

CLINICAL RELEVANCE

The results suggest that site-specific inhibition of MMP-13 may be an interesting strategy to modulate inflammation and reduce bone resorption in osteolytic inflammatory diseases.

Local application of curcumin-loaded nanoparticles as an adjunct to scaling and root planing in periodontitis: Randomized, placebo-controlled, double-blind split-mouth clinical trial

OBJECTIVE

Assess a single local application of curcumin-loaded nanoparticles as an adjunct to scaling and root planing (SRP) in nonsurgical periodontal treatment (NPT).

MATERIALS AND METHODS

Twenty healthy subjects with periodontitis received SRP+PLGA/PLA nanoparticles loaded with 50 μg of curcumin (N-Curc) or SRP+empty nanoparticles. Probing pocket depth (PPD), clinical attachment level (CAL), and bleeding on probing (BOP) were monitored at baseline, 30, 90, and 180 days. IL-1α, IL-6, TNFα, and IL-10 in the gingival crevicular fluid (GCF) were assessed by ELISA, and counts of 40 bacterial species were determined by DNA hybridization at baseline, 3, 7, and 15 days post-therapy.

RESULTS

PPD, CAL, and BOP were similarly and significantly improved in both experimental groups. There was no difference in GCF cytokine levels between experimental groups, although IL-6 was decreased at 3 days only in the N-Curc group. NPT reduced counts of red complex bacterial species in both groups. Veillonella Parvula counts increased significantly only in N-Curc group at 7 days, whereas Aggregatibacter actinomycetemcomitans counts increased significantly only in the control group from day 3 to day 15.

CONCLUSION

We conclude that a single local administration of nanoencapsulated curcumin in periodontally diseased sites had no additive benefits to NPT.

CLINICAL RELEVANCE

Our results showed that a single local application of curcumin-loaded nanoparticles associated with nonsurgical periodontal therapy did not improve clinical outcomes. Hence, our findings do not support the use of curcumin as an adjunct to nonsurgical periodontal therapy.

Periodontitis is an inflammatory disease of oxidative stress: We should treat it that way

Periodontitis is a highly prevalent disease. As it progresses, it causes serious morbidity in the form of periodontal abscesses and tooth loss and, in the latter stages, pain. It is also now known that periodontitis is strongly associated with several nonoral diseases. Thus, patients with periodontitis are at greater risk for the development and/or exacerbation of diabetes, chronic obstructive pulmonary disease, and cardiovascular diseases, among other conditions. Although it is without question that specific groups of oral bacteria which populate dental plaque play a causative role in the development of periodontitis, it is now thought that once this disease has been triggered, other factors play an equal, and possibly more important, role in its progression, particularly in severe cases or in cases that prove difficult to treat. In this regard, we allude to the host response, specifically the notion that the host, once infected with oral periodontal pathogenic bacteria, will mount a defense response mediated largely through the innate immune system. The most abundant cell type of the innate immune system - polymorphonuclear neutrophils - can, when protecting the host from microbial invasion, mount a response that includes upregulation of proinflammatory cytokines, matrix metalloproteinases, and reactive oxygen species, all of which then contribute to the tissue damage and loss of teeth commonly associated with periodontitis. Of the mechanisms referred to here, we suggest that upregulation of reactive oxygen species might play one of the most important roles in the establishment and progression of periodontitis (as well as in other diseases of inflammation) through the development of oxidative stress. In this overview, we discuss both innate and epigenetic factors (eg, diabetes, smoking) that lead to the development of oxidative stress. This oxidative stress then provides an environment conducive to the destructive processes observed in periodontitis. Therefore, we shall describe some of the fundamental characteristics of oxidative stress and its effects on the periodontium, discuss the diseases and other factors that cause oxidative stress, and, finally, review potentially novel therapeutic approaches for the management (and possibly even the reversal) of periodontitis, which rely on the use of therapies, such as resveratrol and other antioxidants, that provide increased antioxidant activity in the host.

Positive effect of curcumin on experimental peridontitis via suppression of IL-1-beta and IL-6 expression level

This study examined the effect of curcumin on T-helper (Th17) and T-regulatory (Treg) cells regarding the mRNA of cytokines/mediators in the gingiva. Thirty-five male albino Wistar rats were divided into four groups: Group 1: periodontitis (n = 9); Group 2: periodontitis with curcumin treatment (n = 8); Group 3: periodontally healthy with curcumin treatment (n = 10); and Group 4: periodontally healthy (n = 8). Curcumin was administered via oral gavage (30 mg/kg/day) for a total of 15 days. The gingival tissues were investigated regarding mRNA expressions of Th17/Treg cytokines with qRT-PCR. The distributional properties of the data were evaluated using the Anderson-Darling normality test. Kruskal-Wallis and Mann-Whitney U tests were employed for multiple group comparisons. Partial least squares regression discriminant analysis (PLS-DA) was used to evaluate the degree of contribution of each mRNA to the separation of treatment groups. When the periodontitis groups were compared, curcumin treatment resulted in lower IL-1β (Group 2 median: 0.002, Group 1 median: 0.12) and IL-6 (Group 2 median: 0.031, Group 1 median: 0.078) and higher IL-17 (Group 2 median: 1.07, Group 1 median: 0.583) relative mRNA expression in Group 2 than in Group 1 (p < 0.001). Group 3 also had higher IL-10 relative expression (median: 0.067) than Groups 1 and 4 (median: 0.028, 0.007, respectively. p < 0.001). These results indicate that curcumin might be a promising agent for the prevention and/or treatment of periodontal diseases due to its decreasing effect on IL-1β and IL-6 mRNA expression.

Balanced oral pathogenic bacteria and probiotics promoted wound healing via maintaining mesenchymal stem cell homeostasis

Objectives

The homeostasis of oral pathogenic bacteria and probiotics plays a crucial role in maintaining the well-being and healthy status of human host. Our previous study confirmed that imbalanced oral microbiota could impair mesenchymal stem cell (MSC) proliferation capacity and delay wound healing. However, the effects of balanced oral pathogenic bacteria and probiotics on MSCs and wound healing are far from clear. Here, the balance of pathogenic bacteria Porphyromonas gingivalis and probiotics Lactobacillus reuteri extracts was used to investigate whether balanced oral microbiota modulate the physiological functions of MSCs and promote wound healing.

Methods

The effects of balanced pathogenic bacteria P. gingivalis and probiotics L. reuteri extracts on gingival MSCs (GMSCs) were tested using the migration, alkaline phosphatase activity, alizarin red staining, cell counting kit-8, real-time PCR, and western blot assays. To investigate the role of balanced pathogenic bacteria P. gingivalis and probiotics L. reuteri extracts in the wound of mice, the wounds were established in the mucosa of palate and were inoculated with bacteria every 2 days.

Results

We found that the balance between pathogenic bacteria and probiotics enhanced the migration, osteogenic differentiation, and cell proliferation of MSCs. Additionally, local inoculation of the mixture of L. reuteri and P. gingivalis promoted the process of wound healing in mice. Mechanistically, we found that LPS in P. gingivalis could activate NLRP3 inflammasome and inhibit function of MSCs, thereby accelerating MSC dysfunction and delaying wound healing. Furthermore, we also found that reuterin was the effective ingredient in L. reuteri which maintained the balance of pathogenic bacteria and probiotics by neutralizing LPS in P. gingivalis, thus inhibiting inflammation and promoting wound healing.

Conclusions

This study revealed that the homeostasis of oral microbiomes played an indispensable role in maintaining oral heath, provided hopeful methods for the prevention and treatment of oral diseases, and had some referential value for other systemic diseases caused by dysfunction of microbiota and MSCs.

The preventive and therapeutic application of garlic and other plant ingredients in the treatment of periodontal diseases

Since ancient times, pharmacologically active ingredients derived from natural sources, including plants and microbials have been used in the treatment of a wide array of diseases, such as atherosclerosis, diabetes mellitus and cancers. Herbal extracts and polyphenols are produced from herbs that contain a variety of ingredients, most of which exhibit anti-inflammatory, anti-oxidative and anti-microbial actions. Gingivitis is triggered by the infection of the periodontal tissues with periodontal disease-causing pathogens present in the dental biofilm. This is accompanied by weak inflammatory immune reactions in the gingiva. In periodontitis, prolonged and excessive inflammation results in the destruction of gingival connective tissue and in the resorption of alveolar bone, leading to tooth loss. There are a number of clinical reports showing the effectiveness of both herbal extracts and polyphenols on periodontal diseases when applied as a mouthwash or dentifrice into the oral cavity. However, to date, at least to the best of our knowledge, there is no clinical report available on the therapeutic effects of garlic or its extract on periodontal diseases, apart from a recent study, which reported that the intake of aged garlic extract (AGE) containing various pharmacologically active sulfur compounds, alleviated the symptoms of gingivitis clinically. The finding suggests that AGE may be a promising candidate for use in the treatment of periodontal diseases, although additional clinical trials are warranted to confirm this. In addition, further studies are required for the clarification of the basic molecular mechanisms through which AGE attenuates gingivitis. In this review, we summarize the beneficial effects of several natural compounds on periodontal disease and describe the possible applications of garlic ingredients in detail.

Periodontal therapeutics: Current host-modulation agents and future directions

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

Curcumin inhibits the expression of proinflammatory mediators and MMP-9 in gingival epithelial cells stimulated for a prolonged period with lipopolysaccharides derived from Porphyromonas gingivalis

Curcumin, a yellow phytochemical found in the rhizomes of Curcuma longa, has various biological effects, including anti-oxidant and anti-inflammatory activities. In the present study, we examined the effect of curcumin on the expression of inflammatory cytokines in human gingival epithelial progenitor cells (HGEPs) stimulated for a prolonged period with lipopolysaccharide (LPS) derived from Porphyromonas gingivalis. The cells were alternately cultured with LPS and/or curcumin every 3 days for 18 days. The expression levels of TNF-α, IL-1β, IL-6, TIMP-1, and MMP-9 in the HGEPs were evaluated by quantitative real-time polymerase chain reaction. Enzyme-linked immunosorbent assay was used to measure the concentrations of these five proteins in the supernatant and nuclear factor (NF)-κB in the nuclear extracts. Curcumin inhibited the mRNA expression levels of TNF-α, IL-1β, IL-6, and MMP-9 in HGEPs treated with curcumin over a prolonged period. Similarly, the expression levels of IL-1β, IL-6, and MMP-9 were decreased in the culture supernatants. NF-κB activity was also inhibited in the cells cultured with curcumin. In conclusion, these findings indicate that curcumin inhibits the expression of inflammatory cytokines and MMP-9 in primary gingival epithelial cells stimulated with P. gingivalis-derived LPS via NF-κB activation.

Cytotoxicity and Pro-/Anti-inflammatory Properties of Cinnamates, Acrylates and Methacrylates Against RAW264.7 Cells

BACKGROUND/AIM

Periodontitis is a chronic inflammatory disease linked to various systemic age-related conditions. It is known that α,β-unsaturated carbonyl compounds such as dietary cinnamates (β-phenyl acrylates) and related (meth)acrylates can have various positive and negative health effects, including cytotoxicity, allergic activity, pro-and anti-inflammatory activity, and anticancer activity. To clarify the anti-inflammatory properties of α,β-unsaturated carbonyl compounds without a phenolic group in the context of periodontal tissue inflammation and alveolar bone loss, we investigated the cytotoxicity and up-regulatory/down-regulatory effect of three trans-cinnamates (trans-cinnamic acid, methyl cinnamate, trans-cinnamaldehyde), two acrylates (ethyl acrylate, 2-hydroxyethyl acrylate), and three methacrylates (methyl methacrylate, 2-hydroxyethyl methacrylate, and triethyleneglycol dimethacrylate) using RAW264.7 cells.

MATERIALS AND METHODS

Cytotoxicity was determined using a cell counting kit (CCK-8) and mRNA expression was determined using real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Pro-inflammatory and anti-inflammatory properties were assessed in terms of expression of mRNAs for cyclo-oxygenase-2 (Cox2), nitric oxide synthase 2 (Nos2), tumor necrosis factor-alpha (Tnfa) and heme oxygenase 1 (Ho1).

RESULTS

The most cytotoxic compound was 2-hydroxyethyl acrylate, followed by ethyl acrylate and cinnamaldehyde (50% lethal cytotoxic concentration, LC₅₀=0.2-0.5 mM). Cox2 mRNA expression was up-regulated by cinnamaldehyde and 2-hydroxyethyl acrylate, particularly by the former. In contrast, the up-regulatory effect on Nos2 mRNA expression was in the order: cinnamaldehyde >> ethyl acrylate ≈ triethyleneglycol dimethacrylate >> methyl methacrylate ≈ methyl cinnamate. On the other hand, cinnamic acid and 2-hydroxyethyl methacrylate had no effect on gene expression. The two acrylates, but not cinnamates and methacrylates, up-regulated the expression of Ho1 mRNA at a non-cytotoxic concentration of 0.1 mM. Expression of Cox2, Nos2 and Tnfa mRNAs induced by Porphyromonas gingivalis lipopolysaccharide was greatly suppressed by cinnamaldehyde, methyl cinnamate and the two acrylates at 0.1 mM (p<0.05), and slightly, but significantly suppressed by cinnamic acid and methacrylates at 0.1-1 mM (p<0.05).

CONCLUSION

Cinnamaldehyde and acrylates exhibited both anti-inflammatory and pro-inflammatory properties, possibly due to their marked ability to act as Michael reaction acceptors, as estimated from the beta-carbon ¹³C-nuclear magnetic resonance spectra. Methyl cinnamate exhibited potent anti-inflammatory activity with less cytotoxicity and pro-inflammatory activity, suggesting that this compound may be useful for treatment of periodontal disease and related systemic diseases.

Impact of curcumin on toll-like receptors

Toll-like receptors (TLRs) have a pivotal role in the activation of innate immune response and inflammation. TLRs can be divided into two subgroups including extracellular TLRs that recognize microbial membrane components (TLR1, 2, 4, 5, 6, and 10), and intracellular TLRs that recognize microbial nucleic acids (TLR3, 7, 8, and 9). Curcumin is a dietary polyphenol from Curcuma longa L. that is reputed to have diverse biological and pharmacological effects. Extensive research has defined the molecular mechanisms through which curcumin mediates its therapeutic effects. One newly defined and important target of curcumin is the TLR, where it exerts an inhibitory effect. In the current study, we focus upon the TLR antagonistic effect of curcumin and curcumin's therapeutic effect as mediated via TLR inhibition. The available evidence indicates that curcumin inhibits the extracellular TLR 2 and 4 and intracellular TLR9 and thereby exerts a therapeutic effect in diseases such as cancer, inflammation, infection, autoimmune, and ischemic disease. Curcumin effectively modulates the TLR response and thereby exerts its potent therapeutic effects.

Dose-response assessment of chemically modified curcumin in experimental periodontitis

BACKGROUND

CMC2.24, a novel tri-ketonic chemically modified compound based on natural di-ketonic curcumin, has been shown to reduce bone loss and inflammatory mediators in experimental periodontitis, however, a potential dose-response relationship was not determined. The purpose of this study was to assess the effects of different doses of CMC2.24 on inflammation and bone resorption in vivo and also to describe on the effects of CMC2.24 on macrophage response.

METHODS

CMC2.24 was administered daily to animals for 28 days by oral gavage, at the following doses: 0 (control), 1, 3, 10, and 30 mg/kg of body weight. Experimental periodontitis was induced by injections of lipopolysaccharide (LPS) into the gingival tissues. Outcomes assessed were bone resorption, detection of tartrate-resistant acid phosphatase, and determination of gene expression. In vitro, macrophages (RAW264.7) were treated with different concentrations of CMC2.24: 1, 3, 10, and 30 μM and then subjected to different activation stimuli. Gene expression, phagocytic activity, production of reactive oxygen species (ROS) and cytokine production were evaluated.

RESULTS

CMC2.24 inhibited bone resorption, osteoclastogenesis, and tumor necrosis factor (TNF)-α expression in vivo. These beneficial responses reached maximum levels at a dose of 1 mg/kg, i.e. no dose-dependent effect. In vitro, CMC2.24 reduced the production of TNF-α and interleukin-10, inhibited phagocytic activity and stimulated production of ROS. A dose-dependent effect was observed only for ROS production.

CONCLUSION

Low doses of CMC2.24 (1 mg/kg/day) administered orally were sufficient to significantly inhibit alveolar bone resorption associated with the experimental periodontal disease; whereas in vitro macrophage inflammatory gene expression and phagocytosis were reduced, whereas production of ROS was stimulated.

Systemic administration of curcumin or piperine enhances the periodontal repair: a preliminary study in rats

OBJECTIVES

Studies have documented the anti-inflammatory effects of spices, which may be related to treatment of chronic diseases. The purpose of this study was to evaluate the influence of curcumin and piperine and their association on experimental periodontal repair in rats.

MATERIALS AND METHODS

Periodontitis was induced via the installation of a ligature around the first molar. After 15 days, the ligatures were removed, and the rats were separated into groups (12 animals per group): (i) curcumin, (ii) piperine, (iii) curcumin+piperine, (iv) corn oil vehicle, and (v) control group (animals had ligature-induced periodontitis but were not treated). The compounds were administered daily, for 15 days by oral gavage. Animals were euthanized at 5 and 15 days, and hemimaxillae and gingival tissues were harvested. Bone repair was assessed by μCT (microcomputer tomography). Histological sections were stained with hematoxylin/eosin (H/E) for the assessment of cellular infiltrate or picrosirius red for quantification of collagen content, and subjected to immunohistochemistry for detecting NF-ĸB. Gingival tissues were used to evaluate levels of TGF-β and IL-10 (ELISA).

RESULTS

Curcumin and piperine increased the TGF-β level, significantly improved the collagen repair, and decreased the cellularity and activation of NF-ĸB in the periodontal tissues, but only curcumin caused a significant increase in early bone repair.

CONCLUSION

Curcumin and piperine promoted a substantive effect on tissue repair; however, there was not synergistic effect of compounds administered in combination.

CLINICAL RELEVANCE

Curcumin and piperine stimulates the tissue repair and may be potential candidates for the treatment of periodontal disease.

Protective effect and related mechanisms of curcumin in rat experimental periodontitis

Background

Curcumin exhibits anti-inflammatory effects and has been suggested as a treatment for inflammatory diseases. The aim of this study was to investigate the effects of curcumin on the lipopolysaccharide induced inflammatory response in rat gingival fibroblasts in vitro and ligation-induced experimental periodontitis in vivo, and to speculate the possible anti-inflammatory mechanism of curcumin.

Methods

The gingival fibroblasts were incubated with different concentrations of curcumin in the absence or presence of lipopolysaccharide (LPS). Concentrations of interleukin-1β(IL-1β), tumor necrosis factor-α (TNF-α), osteoprotegerin (OPG) and soluble receptor activator of nuclear factor kappa-B ligand (RANKL) culture supernatants of rat gingival fibroblasts were determined by enzyme linked immunosorbent assay. The nuclear fraction of rat gingival fibroblasts was extracted and nuclear factor kappa-B (NF-κB) activation was assessed by western blotting to elucidate related mechanisms. Curcumin was given every two days by oral gavage. The gingival inflammation and alveolar bone loss between the first and second molars were observed by hematoxylin and eosin staining. Collagen fibers were observed by picro-sirius red staining. Alveolar bone loss was assessed by micro-CT analysis.

Results

Curcumin attenuated the production of IL-1β and TNF-α in rat gingival fibroblasts stimulated by LPS, and inhibited the LPS-induced decrease in OPG/sRANKL ratio and NF-κB activation. Curcumin significantly reduced gingival inflammation and modulated collagen fiber and alveolar bone loss in vivo.

Conclusions

curcumin modulates inflammatory activity in rat periodontitis by inhibiting NF-κB activation and decreasing the OPG/sRANKL ratio induced by LPS.

Local administration of curcumin-loaded nanoparticles effectively inhibits inflammation and bone resorption associated with experimental periodontal disease

There is evidence indicating that curcumin has multiple biological activities, including anti-inflammatory properties. In vitro and in vivo studies demonstrate that curcumin may attenuate inflammation and the connective tissue destruction associated with periodontal disease. Most of these studies use systemic administration, and considering the site-specific nature of periodontal disease and also the poor pharmacodynamic properties of curcumin, we conducted this proof of principle study to assess the biological effect of the local administration of curcumin in a nanoparticle vehicle on experimental periodontal disease. We used 16 rats divided into two groups of 8 animals according to the induction of experimental periodontal disease by bilateral injections of LPS or of the vehicle control directly into the gingival tissues 3×/week for 4 weeks. The same volume of curcumin-loaded nanoparticles or of nanoparticle vehicle was injected into the same sites 2×/week. µCT analysis showed that local administration of curcumin resulted in a complete inhibition of inflammatory bone resorption and in a significant decrease of both osteoclast counts and of the inflammatory infiltrate; as well as a marked attenuation of p38 MAPK and NF-kB activation. We conclude that local administration of curcumin-loaded nanoparticles effectively inhibited inflammation and bone resorption associated with experimental periodontal disease.

A Chemically Modified Curcumin (CMC 2.24) Inhibits Nuclear Factor κB Activation and Inflammatory Bone Loss in Murine Models of LPS-Induced Experimental Periodontitis and Diabetes-Associated Natural Periodontitis

The purpose of this study was to assess the effect of a novel chemically modified curcumin (CMC 2.24) on NF-κB and MAPK signaling and inflammatory cytokine production in two experimental models of periodontal disease in rats. Experimental model I: Periodontitis was induced by repeated injections of LPS into the gingiva (3×/week, 3 weeks); control rats received vehicle injections. CMC 2.24, or the vehicle, was administered by daily oral gavage for 4 weeks. Experimental model II: Diabetes was induced in adult male rats by streptozotocin injection; periodontal breakdown then results as a complication of uncontrolled hyperglycemia. Non-diabetic rats served as controls. CMC 2.24, or the vehicle, was administered by oral gavage daily for 3 weeks to the diabetics. Hemimaxillae and gingival tissues were harvested, and bone loss was assessed radiographically. Gingival tissues were pooled according to the experimental conditions and processed for the analysis of matrix metalloproteinases (MMPs) and bone-resorptive cytokines. Activation of p38 MAPK and NF-κB signaling pathways was assessed by western blot. Both LPS and diabetes induced an inflammatory process in the gingival tissues associated with excessive alveolar bone resorption and increased activation of p65 (NF-κB) and p38 MAPK. In both models, the administration of CMC 2.24 produced a marked reduction of inflammatory cytokines and MMPs in the gingival tissues, decreased bone loss, and decreased activation of p65 (NF-κB) and p38 MAPK. Inhibition of these cell signaling pathways by this novel tri-ketonic curcuminoid (natural curcumin is di-ketonic) may play a role in its therapeutic efficacy in locally and systemically associated periodontitis.

Molecular signaling mechanisms behind polyphenol-induced bone anabolism

For millennia, in the different cultures all over the world, plants have been extensively used as a source of therapeutic agents with wide-ranging medicinal applications, thus becoming part of a rational clinical and pharmacological investigation over the years. As bioactive molecules, plant-derived polyphenols have been demonstrated to exert many effects on human health by acting on different biological systems, thus their therapeutic potential would represent a novel approach on which natural product-based drug discovery and development could be based in the future. Many reports have provided evidence for the benefits derived from the dietary supplementation of polyphenols in the prevention and treatment of osteoporosis. Polyphenols are able to protect the bone, thanks to their antioxidant properties, as well as their anti-inflammatory actions by involving diverse signaling pathways, thus leading to bone anabolic effects and decreased bone resorption. This review is meant to summarize the research works performed so far, by elucidating the molecular mechanisms of action of polyphenols in a bone regeneration context, aiming at a better understanding of a possible application in the development of medical devices for bone tissue regeneration.

Effects of Curcumin on Tobacco Smoke-induced Hepatic MAPK Pathway Activation and Epithelial-Mesenchymal Transition In Vivo

Tobacco smoke is a major risk factor for hepatic cancer. Epithelial-mesenchymal transition (EMT) induced by tobacco smoke is crucially involved in the initiation and development of cancer. Mitogen-activated protein kinase (MAPK) pathways play important roles in tobacco smoke-associated carcinogenesis including EMT process. The chemopreventive effect of curcumin supplementation against cancers has been reported. In this study, we investigated the effects of tobacco smoke on MAPK pathway activation and EMT alterations, and then the preventive effect of curcumin was examined in the liver of BALB/c mice. Our results indicated that exposure of mice to tobacco smoke for 12 weeks led to activation of ERK1/2, JNK, p38 and ERK5 pathways as well as activator protein-1 (AP-1) proteins in liver tissue. Exposure of mice to tobacco smoke reduced the hepatic mRNA and protein expression of the epithelial markers, while the hepatic mRNA and protein levels of the mesenchymal markers were increased. Treatment of curcumin effectively attenuated tobacco smoke-induced activation of ERK1/2 and JNK MAPK pathways, AP-1 proteins and EMT alterations in the mice liver. Our data suggested the protective effect of curcumin in tobacco smoke-triggered MAPK pathway activation and EMT in the liver of BALB/c mice, thus providing new insights into the chemoprevention of tobacco smoke-associated hepatic cancer. Copyright © 2017 John Wiley & Sons, Ltd.

Anti-inflammatory effect of the Salvia sclarea L. ethanolic extract on lipopolysaccharide-induced periodontitis in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Salvia sclarea L., clary, is an aromatic plant traditionally used in folk medicine for the treatment of various diseases and conditions. Although it has been primarily used as a stomachic, there are data on traditional use of S. sclarea as an agent against gingivitis, stomatitis and aphthae.

AIM OF THE STUDY

The aim of the study was to examine the effect of the S. sclarea ethanolic extract on the lipopolysaccharide (LPS)-induced periodontitis in rats from the immunological and histopathological standpoint.

MATERIAL AND METHODS

Periodontal inflammation in rats was induced by repeated injections of LPS from Escherichia coli into the interdental papilla between the first and second right maxillary molars. The extract was administered two times a day by oral gavage (200mg/kg body weight). The inflammatory status was assessed by the measurements of proinflammatory cytokines interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) of gingival tissues and descriptive analysis of histological sections of periodontium. Chemical characterization of the extract was determined using high performance liquid chromatography system (HPLC). Antioxidant activity of the extract was estimated with two in vitro complementary methods: 2,2-diphenyl-1-picrylhydrazyl and β-carotene/linoleic acid models.

RESULTS

Treatment with S. sclarea extract, compared to the untreated group of the rats, significantly diminished the process of inflammation decreasing the levels of IL-1β, IL-6 and TNF-α, reducing the gingival tissue lesions and preserving bone alveolar resorption. Considerably smaller number of inflammatory cells and larger number of fibroblasts was noticed. The administration of the extract three days earlier did not have significant preventive effects. Rosmarinic acid was the predominant compound in the extract. The extract showed strong antioxidant effects in both test systems.

CONCLUSIONS

S. sclarea extract manifested anti-inflammatory effect in LPS-induced periodontitis suggesting that it may have a role as a therapeutic agent in periodontal diseases. Having in mind that overproduction of reactive oxygen species is connected to periodontitis, the strong antioxidant capacity may be contributable to anti-inflammatory properties of the extract.

Curcumin improves LPS-induced preeclampsia-like phenotype in rat by inhibiting the TLR4 signaling pathway

INTRODUCTION

Abnormal inflammation mediated by Toll-like receptor 4 (TLR4) signaling pathway contributes to preeclampsia (PE). Because curcumin can inhibit TLR4 signaling pathway, we investigated its effects on a PE rat model.

METHODS

Twenty-one pregnant rats were randomly divided into three groups: 1) seven rats were injected 0.5 μg/kg lipopolysaccharide (LPS) on gestational day (GD) 5 to create a PE model (LPS-treated group), 2) seven rats were injected with a similar dosage of LPS and further treated with curcumin (0.36 mg/kg) (LPS-curcumin-treated group), 3) seven rats received saline (control group). Blood pressure and urinary protein level were observed. Immunostaining and periodic acid-Schiff staining of placenta were conducted. TLR4 and downstream Nuclear Factor-κB (NF-κB) expressions of placenta were analyzed by Western blot and immunohistochemistry. IL-6 and MCP-1 in rat serum and placenta were determined by ELISA and qRT-PCR.

RESULTS

Compared to LPS-treated group, LPS-curcumin-treated group had decreased blood pressure and urinary protein level, similar to control group. Furthermore, deficient trophoblast invasion and spiral artery remodeling induced by LPS were improved by curcumin. Increased TLR4, NF-κB and IL-6, MCP-1 protein expressions in LPS-treated group were significantly decreased after curcumin administration.

DISCUSSION

Curcumin improves the PE-like phenotype in rat model by reducing abnormal inflammation related to TLR4 signaling pathway.

Curcumin Suppresses MAPK Pathways to Reverse Tobacco Smoke-induced Gastric Epithelial-Mesenchymal Transition in Mice

Tobacco smoke (TS) has been shown to cause gastric cancer. Epithelial-mesenchymal transition (EMT) is a crucial pathophysiological process in cancer development. Mitogen-activated protein kinase (MAPK) pathways play central roles in tumorigenesis including EMT process. Curcumin is a promising chemopreventive agent for several types of cancers. In the present study, we investigated the effects of TS on MAPK pathway activation and EMT alterations in the stomach of mice, and the preventive effect of curcumin was further examined. Results showed that exposure of mice to TS for 12 weeks resulted in activation of extracellular regulated protein kinases 1 and 2 (ERK1/2), the Jun N-terminal kinase (JNK), p38, and ERK5 MAPK pathways as well as activator protein 1 (AP-1) proteins in stomach. TS reduced the mRNA and protein expression levels of the epithelial markers E-cadherin and ZO-1, while the mRNA and protein expression levels of the mesenchymal markers vimentin and N-cadherin were increased. Treatment of curcumin effectively abrogated TS-triggered gastric activation of ERK1/2 and JNK MAPK pathways, AP-1 proteins, and EMT alterations. These results suggest for the first time the protective effects of curcumin in long-term TS exposure-induced gastric MAPK activation and EMT, thus providing new insights into the pathogenesis and chemoprevention of TS-associated gastric cancer.

Inhibition of tobacco smoke-induced bladder MAPK activation and epithelial-mesenchymal transition in mice by curcumin

Tobacco smoke (TS) has been shown to cause bladder cancer. Epithelial-mesenchymal transition (EMT) is a crucial pathophysiological process in cancer development. MAPK pathways play central roles in tumorigenesis including EMT process. Curcumin is a promising chemopreventive agent for several types of cancers. In the present study we investigated the effects of TS on MAPK pathway activation and EMT alterations in the bladder of mice, and the preventive effect of curcumin was further examined. Results showed that exposure of mice to TS for 12 weeks resulted in activation of ERK1/2, JNK, p38 and ERK5 MAPK pathways as well as AP-1 proteins in bladder. TS reduced mRNA and protein expression levels of epithelial markers E-cadherin and ZO-1, while mRNA and protein expression levels of the mesenchymal markers vimentin and N-cadherin were increased. Curcumin treatment effectively attenuated TS-triggered activation of ERK1/2, JNK and p38 MAPK pathways, AP-1 proteins and EMT alterations in bladder tissue. These results suggest the protective effects of curcumin in TS-induced MAPK activation and EMT, thus providing new insights into the chemoprevention of TS-associated bladder cancer.

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

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

Comparative evaluation of the efficacy of two controlled release devices: Chlorhexidine chips and indigenous curcumin based collagen as local drug delivery systems

Aim:

To comparatively evaluate the therapeutic efficacy of chlorhexidine (CHX) chips (Periocol-CG) and indigenous curcumin (CU) based collagen as adjuncts to scaling and root planning in the nonsurgical management of chronic periodontitis.

Materials and Methods:

A total of 120 sites from 60 patients presenting with chronic periodontitis (age group 25-55 years) of both sexes, with pocket depth of ≥5 mm with radiographic evidence of bilateral bone loss were earmarked for the study. A split mouth design was employed, and all the clinical parameters-plaque index, gingival index, probing pocket depth (PPD) and clinical attachment levels (CAL) were recorded at baseline, 1 month, 3 months, and 6 months. However, the microbiological parameters, i.e., N-benzoyl-DL-arginine-β-naphthylamide (BANA) test and microbial colony count were recorded at baseline, 3 months and 6 months postoperatively.

Results:

Significant reduction in plaque and gingival index scores were observed in both groups at the end of the study period, i.e., 6 months. The microbiological parameters (BANA test, microbial colony count), PPD and CAL levels also showed significant improvement in both groups. However, at the end of the study period CHX group showed greater improvement in all of these parameters compared to CU collagen group.

Conclusion:

Future directions of this study should include targeting the beneficial effects of these local drug delivery systems at varied concentrations so that they could be utilized to achieve the maximum beneficial therapeutic effects in the nonsurgical treatment of periodontal disease.

Anethole, a Medicinal Plant Compound, Decreases the Production of Pro-Inflammatory TNF-α and IL-1β in a Rat Model of LPS-Induced Periodontitis

Periodontitis (PD) is known to be one of most prevalent worldwide chronic inflammatory diseases. There are several treatments including antibiotics for PD; however, since drug resistance is an increasing problem, new drugs particularly derived from plants with fewer side effects are required. The effects of trans-anethole on IL-1 β and TNF-α level in a rat model of PD were investigated and compared to ketoprofen. Eschericia coli lipopolysaccharide (LPS, 30 µg) was injected bilaterally into the palatal gingiva (3 µL/site) between the upper first and second molars every two days for 10 days in anesthetized rats. Administration of either trans-anethole (10 or 50 mg/Kg, i.p.) or ketoprofen (10 mg/Kg, i.p.) was started 20 minute before LPS injection and continued for 10 days. Then, IL-1β and TNF-α levels were measured in blood samples by ELISA at day 0 (control) and at day 10. Anethole at both concentrations significantly suppressed IL-1β and TNF-α production when compared to LPS-treated rats. The suppressive effects of anethole on LPS-induced pro-inflammatory cytokines were almost similar as seen with ketoprofen. In conclusion, the present results suggest that anethole may have a potent inhibitory effect on PD through suppression of pro-inflammatory molecules; therefore it could be a novel therapeutic strategy for PD.

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.

Inhibition of microsomal prostaglandin E synthase-1 by aminothiazoles decreases prostaglandin E2 synthesis in vitro and ameliorates experimental periodontitis in vivo

The potent inflammatory mediator prostaglandin E2 (PGE2) is implicated in the pathogenesis of several chronic inflammatory conditions, including periodontitis. The inducible enzyme microsomal prostaglandin E synthase-1 (mPGES-1), catalyzing the terminal step of PGE2 biosynthesis, is an attractive target for selective PGE2 inhibition. To identify mPGES-1 inhibitors, we investigated the effect of aminothiazoles on inflammation-induced PGE2 synthesis in vitro, using human gingival fibroblasts stimulated with the cytokine IL-1β and a cell-free mPGES-1 activity assay, as well as on inflammation-induced bone resorption in vivo, using ligature-induced experimental periodontitis in Sprague-Dawley rats. Aminothiazoles 4-([4-(2-naphthyl)-1,3-thiazol-2-yl]amino)phenol (TH-848) and 4-(3-fluoro-4-methoxyphenyl)-N-(4-phenoxyphenyl)-1,3-thiazol-2-amine (TH-644) reduced IL-1β-induced PGE2 production in fibroblasts (IC50 1.1 and 1.5 μM, respectively) as well as recombinant mPGES-1 activity, without affecting activity or expression of the upstream enzyme cyclooxygenase-2. In ligature-induced experimental periodontitis, alveolar bone loss, assessed by X-ray imaging, was reduced by 46% by local treatment with TH-848, compared to vehicle, without any systemic effects on PGE2, 6-keto PGF1α, LTB4 or cytokine levels. In summary, these results demonstrate that the aminothiazoles represent novel mPGES-1 inhibitors for inhibition of PGE2 production and reduction of bone resorption in experimental periodontitis, and may be used as potential anti-inflammatory drugs for treatment of chronic inflammatory diseases, including periodontitis.

Potent anti-inflammatory effects of systemically administered curcumin modulate periodontal disease in vivo

BACKGROUND AND OBJECTIVE

Curcumin is a plant-derived dietary spice with various biological activities, including anticarcinogenic and anti-inflammatory effects. Its therapeutic applications have been studied in a variety of conditions, including rheumatoid arthritis, colon cancer and depression, but no studies have evaluated the effects of curcumin on periodontal disease in vivo.

MATERIAL AND METHODS

Experimental periodontal disease was induced in rats by placing cotton ligatures around both lower first molars. Curcumin was given to the rats by the intragastric route daily at two dosages (30 and 100 mg/kg) for 15 d. Control animals received ligatures but only the corn oil vehicle by gavage, and no treatment-negative control animals were included. Bone resorption was assessed by micro-computed tomography, and the inflammatory status was evaluated by stereometric analysis. Both RT-qPCR and ELISA were used to determine the expression of interleukin-6, tumor necrosis factor-α and prostaglandin E(2) synthase in the gingival tissues. Modulation of p38 MAPK and nuclear factor-κB activation were assessed by western blotting.

RESULTS

Bone resorption was effectively induced in the experimental period, but it was not affected by either dose of curcumin. Curcumin effectively inhibited cytokine gene expression at both the mRNA and the protein level and produced a dose-dependent inhibition of the activation of nuclear factor-κB in the gingival tissues. Activation of p38 MAPK was not inhibited by curcumin. Curcumin-treated animals also presented a marked reduction of the inflammatory cell infiltrate and increased collagen content and fibroblastic cell numbers.

CONCLUSION

Curcumin did not prevent alveolar bone resorption, but its potent anti-inflammatory effect suggests that it may have a therapeutic potential in periodontal diseases.