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)-1ß, 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.

Infection and apoptosis associated with inflammation in periodontitis: An immunohistologic study.

OBJECTIVE: Evidence of increased apoptosis is observed in periodontitis and may be associated with destruction of the periodontal tissue caused by the increased cell death, with the release of danger signals and subsequent stimulation of the proinflammatory processes. However, the exact mechanisms associated with these processes remain unclear. This study aimed to investigate the presence of the periodontal pathogen Treponema denticola, apoptosis, high mobility group box 1 as a damage-associated molecular pattern, and several inflammatory markers in periodontitis and gingivitis subjects. MATERIALS AND METHODS: Soft tissue specimens from gingival tissues of periodontitis and gingivitis patients were used for immunohistochemical and immunofluorescence staining of T. denticola chymotrypsin-like proteinase (CTLP), apoptosis markers, high mobility group box 1, Toll-like receptor 4, inflammatory cell markers, and proinflammatory cytokines. RESULTS: Treponema denticola was detected in all periodontitis-affected tissues. This was associated with a significant increase in the number of apoptotic cells, including macrophages, alterations in the expression of high mobility group box 1 and its receptor, and increased levels of proinflammatory cytokines compared with gingivitis. CONCLUSIONS: In summary, the presence of T. denticola (especially its CTLP), apoptosis, high mobility group box 1, and inflammatory markers suggests their potential involvement in the pathogenesis of periodontitis.

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.

Subinhibitory concentrations of tetracyclines induce lipopolysaccharide shedding by Porphyromonas gingivalis and modulate the host inflammatory response.

BACKGROUND AND OBJECTIVE: Antibiotics at below minimal inhibitory concentrations (MICs) may induce various biological responses in bacteria. In this study, we hypothesized that subinhibitory concentrations (subICs) of tetracycline and doxycycline induce the shedding of lipopolysaccharide (LPS) by Porphyromonas gingivalis and, as a consequence, may contribute to enhancing the host inflammatory response associated with periodontitis. MATERIAL AND METHODS: A polymyxin-based enzyme-linked immunosorbent assay was used to quantify LPS shedding by P. gingivalis grown in the presence of subICs of tetracycline and doxycycline. A macrophage model was used to show that tetracycline- and doxycycline-mediated LPS shedding by P. gingivalis can induce cytokine secretion. The secretion of interleukin (IL)-1ß, IL-8, and tumor necrosis factor-α was quantified by enzyme-linked immunosorbent assay. RESULTS: LPS was shed spontaneously in a time-dependent way by P. gingivalis during growth. LPS shedding was significantly increased by growth in the presence of subICs of tetracycline and doxycycline corresponding to 1/20 of their MICs (0.025 µg/mL for tetracycline and 0.0125 µg/mL for doxycycline). This shedding was not associated with an increased rate of bacterial cell lysis. Stimulating macrophages with a P. gingivalis culture supernatant induced the secretion of IL-1ß, IL-8 and tumor necrosis factor-α when the bacteria were grown in the presence of 1/20 MIC of the antibiotics. CONCLUSION: Our study showed that growing P. gingivalis in the presence of subICs of either tetracycline or doxycycline induces LPS shedding. Shed LPS may in turn increase cytokine secretion in a macrophage model.

Green tea extract and its major constituent, epigallocatechin-3-gallate, induce epithelial beta-defensin secretion and prevent beta-defensin degradation by Porphyromonas gingivalis.

BACKGROUND AND OBJECTIVE: Antimicrobial peptides, such as beta-defensins, secreted by gingival epithelial cells, are thought to play a major role in preventing periodontal diseases. In the present study, we investigated the ability of green tea polyphenols to induce human beta-defensin (hBD) secretion in gingival epithelial cells and to protect hBDs from proteolytic degradation by Porphyromonas gingivalis. MATERIAL AND METHODS: Gingival epithelial cells were treated with various amounts (25-200 µg/mL) of green tea extract or epigallocatechin-3-gallate (EGCG). The secretion of hBD1 and hBD2 was measured using ELISAs, and gene expression was quantified by real-time PCR. The treatments were also carried out in the presence of specific kinase inhibitors to identify the signaling pathways involved in hBD secretion. The ability of green tea extract and EGCG to prevent hBD degradation by proteases of P. gingivalis present in a bacterial culture supernatant was evaluated by ELISA. RESULTS: The secretion of hBD1 and hBD2 was up-regulated, in a dose-dependent manner, following the stimulation of gingival epithelial cells with a green tea extract or EGCG. Expression of the hBD gene in gingival epithelial cells treated with green tea polyphenols was also increased. EGCG-induced secretion of hBD1 and hBD2 appeared to involve extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase. Lastly, green tea extract and EGCG prevented the degradation of recombinant hBD1 and hBD2 by a culture supernatant of P. gingivalis. CONCLUSION: Green tea extract and EGCG, through their ability to induce hBD secretion by epithelial cells and to protect hBDs from proteolytic degradation by P. gingivalis, have the potential to strengthen the epithelial antimicrobial barrier. Future clinical studies will indicate whether these polyphenols represent a valuable therapeutic agent for treating/preventing periodontal diseases.

Relationship between halitosis and periodontal disease - associated oral bacteria in tongue coatings.

AIM: The objective of our study was to investigate the relationship between halitosis and oral bacteria in tongue coating (TC) and saliva samples from patients with halitosis, and to evaluate the effect of tongue cleaning on halitosis. METHODS: Ninety-four participants complaining of oral malodour were included in the study. Organoleptic (OR) values, volatile sulphur compound (VSC) concentrations determined by gas chromatography and TC scores were used as clinical parameters of halitosis. Quantitative real-time polymerase chain reactions were used to determine the numbers of periodontal disease-associated oral bacteria. RESULTS: There was a significant correlation between TC scores and OR values, methylmercaptan (CH3 SH) concentrations and VSC concentrations (Spearman's rank-correlation coefficient test, P < 0.01). There was also a positive correlation between the clinical parameters of halitosis and total bacterial numbers and Prevotella intermedia, Fusobacterium nucleatum and Campylobacter rectus concentrations in the TC samples. However, there was no similar correlation with respect to the saliva samples. The participants were sub-divided into two groups based on whether they had the habit of tongue cleaning or not. The participants with the habit of tongue cleaning had significantly lower OR scores, VSC concentrations and P. intermedia, F. nucleatum and C. rectus levels than the other participants (Mann-Whitney U-test, P < 0.05). CONCLUSION: These results suggested that periodontal disease-associated oral bacteria in TCs are closely related to halitosis and that tongue cleaning may be an effective method for improving halitosis.

Cranberry proanthocyanidins act in synergy with licochalcone A to reduce Porphyromonas gingivalis growth and virulence properties, and to suppress cytokine secretion by macrophages.

AIMS: Periodontitis is an inflammatory disease of polymicrobial origin that affects the tooth-supporting tissues. With the spread of antibiotic resistance among pathogenic bacteria, alternative strategies are required to better control infectious diseases such as periodontitis. The aim of our study was to investigate whether two natural compounds, A-type cranberry proanthocyanidins (AC-PACs) and licochalcone A, act in synergy against Porphyromonas gingivalis and the host inflammatory response of a macrophage model. METHODS AND RESULTS: Using a checkerboard microtitre test, AC-PACs and licochalcone A were found to act in synergy to inhibit P. gingivalis growth and biofilm formation. Fluorescein isothiocyanate-labelled P. gingivalis adhesion to oral epithelial cells was also inhibited by a combination of the two natural compounds in a synergistic manner. Fluorometric assays showed that although AC-PACs and licochalcone A reduced both MMP-9 and P. gingivalis collagenase activities, no synergy was obtained with a combination of the compounds. Lastly, AC-PACs and licochalcone A also acted in synergy to reduce the lipopolysaccharide (LPS)-induced secretion of the pro-inflammatory mediators IL-1ß, TNF-α, IL-6 and IL-8 in a macrophage model. CONCLUSIONS: A-type cranberry proanthocyanidins and licochalcone A, natural compounds from cranberry and licorice, respectively, act in synergy on both P. gingivalis and the host immune response, the two principal etiological factors of periodontitis. SIGNIFICANCE AND IMPACT OF THE STUDY: The combined use of AC-PACs and licochalcone A may be a potential novel therapeutic strategy for the treatment and prevention of periodontal disease.

Licorice and its potential beneficial effects in common oro-dental diseases.

Licorice, the name given to the roots and stolons of Glycyrrhiza species, has been used since ancient times as a traditional herbal remedy. Licorice contains several classes of secondary metabolites with which numerous human health benefits have been associated. Recent research suggests that licorice and its bioactive ingredients such as glycyrrhizin, glabridin, licochalcone A, licoricidin, and licorisoflavan A possess potential beneficial effects in oral diseases. This paper reviews the effects of licorice and licorice constituents on both the oral microbial pathogens and the host immune response involved in common ora-dental diseases (dental caries, periodontitis, candidiasis, and recurrent aphthous ulcers). It also summarizes results of clinical trials that investigated the potential beneficial effects of licorice and its constituents for preventing/treating oro-dental diseases.

Phylogeny and taxonomic revision of the Planistromellaceae including its coelomycetous anamorphs: contributions towards a monograph of the genus Kellermania.

The core species of the family Planistromellaceae are included in the teleomorphic genera Planistroma and Planistromella and the connected anamorphic, coelomycetous genera Alpakesa, Kellermania, and Piptarthron. These genera have been defined primarily on the basis of ascospore septation or number of conidial appendages. Due to a lack of DNA sequence data, phylogenetic placement of these genera within the Dothideomycetes, evaluation of monophyly, and questions about generic boundaries could not be adequately addressed in the past. Isolates of nearly all of the known species in these genera were studied genetically and morphologically. DNA sequence data were generated for the nSSU, ITS, nLSU, and RPB1 markers and analysed phylogenetically. These results placed the Planistromellaceae, herein recognised as a distinct family, in an unresolved position relative to other genera within the order Botryosphaeriales. Species representing the core genera of the Planistromellaceae formed a clade and evaluation of its topology revealed that previous morphology-based definitions of genera resulted in an artificial classification system. Alpakesa, Kellermania, Piptarthron, Planistroma, and Planistromella are herein recognised as belonging to the single genus Kellermania. The following new combinations are proposed: Kellermania crassispora, K. dasylirionis, K. macrospora, K. plurilocularis, and K. unilocularis. Five new species are described, namely K. con- fusa, K. dasylirionicola, K. micranthae, K. ramaleyae, and K. rostratae. Descriptions of species in vitro and a key to species known from culture are provided.

Assessment of radiofrequency self-heating around a metallic wire with MR T1-based thermometry.

Heat produced by a magnetic resonance (MR) imaging sequence in the vicinity of a conductive wire (pacemaker, electrodes, or catheter), is a subject of interest for the assessment of patient safety during imaging. For this purpose, the measurement of temperature rises during an MR imaging sequence using MR T1-based thermometry provides several advantages, mainly in its ability to retrieve in situ real-time thermal maps. Recent studies investigated the heat produced by an independent radiofrequency pulse, assessing MR imaging sequence heating using a specific MR thermometry sequence. This study focuses on self-heating for which the radiofrequency pulses used for measuring temperature create the heat. An experimental design was set up to evaluate T1-based thermometry self-heating using a coupled/decoupled wire and to compare it with a reference temperature gathered by an optical fiber device. For the tested experimental set up, T1-based thermometry is in fairly good agreement with optical fiber reference temperature.

Soluble CD14 induces cytokine release by human oral epithelial cells.

BACKGROUND AND OBJECTIVE: The epithelial cell barrier is the first line of host defense against bacterial aggression in periodontal sites. In view of the fact that oral epithelial cells do not express membrane CD14 and that high levels of the soluble form of the CD14 receptor have been detected in the gingival crevicular fluid of patients with periodontitis, we investigated the effects of recombinant soluble CD14 (rsCD14), alone and in combination with Aggregatibacter actinomycetemcomitans lipopolysaccharide (LPS) on the inflammatory response of human oral epithelial cells. MATERIAL AND METHODS: The oral epithelial cell line GMSM-K was stimulated with rsCD14, alone or in combination with A. actinomycetemcomitans LPS, and the levels of the inflammatory mediators interleukin (IL)-6, IL-8 and chemokine (C-C motif) ligand 5 (CCL5) were determined using ELISAs. Activation of the transcription factors nuclear factor-κB (NF-κB) and activator protein-1 was also monitored using ELISAs. RESULTS: rsCD14 significantly induced the secretion of IL-6, IL-8 and CCL5 by oral epithelial cells. The combination of rsCD14 and A. actinomycetemcomitans LPS augmented this effect. Activation of the NF-κB pathway was significantly increased in epithelial cells treated with rsCD14 compared with a nonstimulated control, whereas there was no effect on the activation of activator protein-1. CONCLUSION: rsCD14 stimulated the inflammation cascade in oral epithelial cells, both alone or when associated with bacterial LPS, through an NF-κB-dependent pathway. This suggests that the presence of soluble CD14 in periodontitis lesions may contribute to the inflammatory process of periodontal disease.

Inhibition of host- and bacteria-derived proteinases by natural anthocyanins.

BACKGROUND AND OBJECTIVES: Host- and bacteria-derived proteinases are considered to play critical roles in periodontitis progression. This study investigated the ability of a blackcurrant extract and its major anthocyanins (cyanidin-3-O-glucoside, cyanidin-3-O-rutinoside and delphinidin-3-O-rutinoside) to inhibit the activity of matrix metalloproteinases (MMPs), neutrophil elastase and periodontopathogen (Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola) proteinases. MATERIAL AND METHODS: Enzyme inhibition was detected using fluorometric and colorimetric assays after incubating blackcurrant extract and its major anthocyanins (at concentrations of 6.25, 12.5, 25 and 50 µg/mL) with MMPs, elastase or bacterial proteinases, along with their specific substrates. Substrate degradation was recorded every hour for up to 4 h. RESULTS: The blackcurrant extract (50 µg/mL) inhibited all proteinases tested. MMP-1 and MMP-9 were significantly inhibited by pure anthocyanins at concentrations ranging from 6.25 to 50 µg/mL. Elastase activity was inhibited by cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside in the range of 6.25-50 µg/mL and by delphinidin-3-O-rutinoside at 50 µg/mL. P. gingivalis, T. forsythia and T. denticola proteinases were also significantly inhibited by pure anthocyanins. In all cases, enzyme inhibition was time-dependent. CONCLUSION: Our study showed that a blackcurrant extract and its major anthocyanins were able to inhibit the activity of host- and bacteria-derived proteinases. This suggests that such natural compounds may represent promising agents for use in adjunctive treatments for periodontitis.

Epidermal growth factor released from platelet-rich plasma promotes endothelial cell proliferation in vitro.

BACKGROUND AND OBJECTIVE: The therapeutic benefits of platelet-rich plasma (PRP) for the promotion of healing and regeneration of periodontal tissues are thought to result from enrichment in growth factors released from platelets. The aim of this study was to evaluate the effects of specific growth factors released from PRP on endothelial cell proliferation. MATERIAL AND METHODS: The levels of vascular endothelial growth factor (VEGF), platelet-derived growth factor BB (PDGF-BB), basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) in supernatants of calcium- and thrombin-activated PRP samples from five donors were quantified by enzyme-linked immunosorbent assay. Supernatants were treated with neutralizing antibodies specific to each growth factor, and the effects of these treatments on human umbilical vein endothelial cell (HUVEC) proliferation in vitro were determined. The effect of removing EGF from PRP supernatants with antibody-coated beads on HUVEC proliferation was also tested. RESULTS: Average concentrations of VEGF, PDGF-BB, bFGF and EGF in PRP supernatants were 189, 27,190, 39.5 and 513 pg/mL, respectively. The addition of EGF neutralizing antibodies to the PRP supernatants significantly reduced HUVEC proliferation (up to 40%), while such an inhibition was not observed following neutralization of the other growth factors. Removal of EGF from PRP supernatants by treatment with antibody-coated beads also resulted in a significant decrease in HUVEC proliferation. Recombinant EGF increased HUVEC proliferation in vitro in a dose-dependent manner. CONCLUSION: This study showed that PRP supernatants are highly mitogenic for endothelial cells and provided evidence that this effect may be due, at least in part, to the presence of EGF. In vivo experiments are needed to confirm the roles of specific growth factors released from PRP in the healing of oral surgical and/or periodontal wounds.

Growth of a single bubble in semi-hard cheese: Comparison between simulation and experiment.

This paper proposes a model for bubble growth in semi-hard cheese coupling mechanical behaviour and mass transport. The modelling follows previous work centred on the mechanical aspects, and focuses in this paper on the mass transport phenomena. Data are compared to experimental results obtained on industrial-size cheeses, both under the rind and at core, and a sensitivity study is conducted to discuss the results. The model is in agreement with experiment at core, and underlines the great influence of the carbon dioxide production rate and the amount of cheese material surrounding the bubble on bubble growth. Under the rind, the model yielded poorer agreement, due to the fact that this region in the cheese is less homogeneous, and therefore with more intra- and inter-batch variation on the parameters that were characterized.

PD-1 inhibition in malignant melanoma and lack of clinical response in chronic lymphocytic leukemia in the same patients: a case series.

Chronic lymphocytic leukemia (cll) is the most common adult leukemia in the Western world. Unfortunately, affected patients are often immunosuppressed and at increased risk of infection and secondary malignancy. Previous meta-analysis has found that patients with cll have a risk of melanoma that is increased by a factor of 4 compared with the general population. Recent advances in the understanding of the PD receptor pathway have led to immunotherapies that target cancer cells. The use of PD-1 inhibitors is now considered first-line treatment for BRAF wild-type metastatic melanoma. Interestingly, early preclinical data suggest that inhibition of that pathway could also be used in the treatment of cll; however, recent clinical data did not support the effectiveness of that approach. In this case series, we highlight 2 cases in which patients with cll and concurrent malignant melanoma underwent treatment with PD-1 inhibitors and were found to experience reductions in their white blood cell counts without improvement in their hemoglobin. Those cases further illustrate that treatment of cll with PD-1 inhibitors is ineffective.

Detection of herpetic viruses in gingival crevicular fluid of patients suffering from periodontal diseases: prevalence and effect of treatment.

BACKGROUND/AIM: Although the role of bacteria in the etiology of periodontitis is well established, it has been suggested that herpetic viruses could contribute to the initiation and progression of this disease. The aim of this study was to determine the prevalence of human cytomegalovirus (HCMV), Epstein-Barr virus (EBV) and herpes simplex virus (HSV) in gingival crevicular fluid (GCF) samples obtained from periodontally healthy, gingivitis and periodontitis patients. In addition, the effect of periodontal treatment (scaling and root planing) on the persistence of herpetic viruses was evaluated in a sub-group of patients suffering from chronic periodontitis. METHODS: The presence of viruses in GCF samples was assessed by a nested PCR amplification technique. The persistence of viruses in periodontal sites was evaluated following a scaling and root planing therapy. RESULTS: A statistically significant higher prevalence of HCMV was observed in periodontitis patients as compared to healthy control subjects (35 vs. 8%, respectively; P = 0.0377). A trend for a higher prevalence of HSV was also noted in the periodontitis group, in comparison with healthy control subjects. In addition, a higher prevalence of HCMV was associated with deep periodontal pockets in subjects suffering from periodontitis. In the sub-group of periodontitis patients, periodontal therapy resulted in the elimination (HCMV and EBV) or reduction (HSV) of the herpetic viruses. CONCLUSIONS: This study showed that the prevalence of HCMV and HSV viruses in GCF is higher in patients suffering from periodontitis compared to periodontally healthy subjects, and that the prevalence of HCMV is higher in deep periodontal pockets. It also brought evidences that periodontal therapy may be associated with virus elimination in diseased sites.

Porphyromonas gingivalis mediates the shedding and proteolysis of complement regulatory protein CD46 expressed by oral epithelial cells.

INTRODUCTION: Human cells express membrane-bound complement regulatory proteins to prevent complement-mediated autologous tissue damage. In this study, we hypothesized that Porphyromonas gingivalis, the major etiological agent of chronic periodontitis, causes the shedding or proteolysis of the complement regulatory protein CD46 expressed by oral epithelial cells. METHODS: Oral epithelial cells were treated with a culture of P. gingivalis before measurement of membrane-bound and shed CD46 by enzyme-linked immunosorbent assay (ELISA). The effect of soluble recombinant CD46 on secretion of interleukin-8 (IL-8) by epithelial cells was evaluated by ELISA. The susceptibility of soluble recombinant CD46 to proteolytic degradation by cells and purified Lys-gingipain of P. gingivalis was investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis/western immunoblotting analysis. RESULTS: Oral epithelial cells treated with a culture of P. gingivalis showed a lower reactivity with antibodies directed to CD46. ELISA revealed that such a treatment resulted in increased amounts of CD46 in the conditioned media suggesting that P. gingivalis caused the shedding of membrane-anchored CD46. Stimulation of epithelial cells with soluble recombinant CD46 induced IL-8 secretion in a dose-dependent manner. Whole cells and purified Lys-gingipain of P. gingivalis degraded recombinant CD46 in a dose-dependent manner. CONCLUSION: This study showed the ability of P. gingivalis to induce the shedding/ proteolysis of CD46 from the surface of oral epithelial cells. This may render host cells susceptible to the complement system and contribute to tissue damage and the inflammatory process in periodontitis.

Treponema denticola peptidoglycan induces the production of inflammatory mediators and matrix metalloproteinase 9 in macrophage-like cells.

BACKGROUND AND OBJECTIVE: Treponema denticola is a key pathogen associated with periodontitis, a chronic inflammatory disease affecting tooth-supporting tissues. In the present study, we investigated the response of human macrophage-like cells to stimulation by peptidoglycan isolated from T. denticola. We also studied the effect of the peptidoglycan preparation on the phosphorylation state of kinases. MATERIAL AND METHODS: Monoblastic leukemia cells (U937 strain) were differentiated into adherent macrophage-like cells using phorbol myristic acid prior to being stimulated for 6 or 24 h with various amounts of T. denticola peptidoglycan. Secreted inflammatory mediators were quantified by enzyme-linked immunosorbent assays. The phosphorylation state of kinases was determined by immunoblotting. RESULTS: The T. denticola peptidoglycan preparation, which was non-toxic for macrophage-like U937 leukemia cells at the concentration used, significantly increased, in a dose-dependent manner, the secretion of the pro-inflammatory cytokines tumor necrosis factor alpha, interleukin-1beta and interleukin-6. It also increased the secretion of two potent chemokines, interleukin-8 (IL-8) and regulated on activation normal T cell expressed and secreted (RANTES). T. denticola peptidoglycan also induced a significant increase in the secretion of prostaglandin E(2) and matrix metalloproteinase 9 by macrophage-like cells. The phosphorylation state of several kinases, including extracellular regulated protein-serine kinase 2 (+99%), G protein-coupled receptor-serine kinase 2 (+50%), Yes-related protein-tyrosine kinase (+44%) and extracellular regulated protein-serine kinase 1 (+30%) also increased following stimulation with the peptidoglycan preparation. CONCLUSION: T. denticola peptidoglycan activates intracellular signaling pathways, leading to an increased production of inflammatory mediators by macrophage-like cells.

Naringenin inhibits human osteoclastogenesis and osteoclastic bone resorption.

BACKGROUND AND OBJECTIVE: Naringenin, a naturally occurring flavonoid, possesses a wide range of pharmacological properties. The purpose of this study was to investigate the effect of naringenin on human osteoclastogenesis and osteoclastic bone resorption. MATERIAL AND METHODS: Naringenin was tested in a human osteoclastogenesis model using primary osteoclast precursor cells activated by receptor activator of nuclear factor-kappaB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) for 6 days. Osteoclastogenesis was assessed by determining the number of tartrate-resistant acid phosphatase (TRAP)-stained multinuclear cells, while the secretion of factors involved in osteoclastogenesis was assessed using enzyme-linked immunosorbent assays. The effect of naringenin on bone resorption was investigated using an OsteoAssay human bone plate coupled with an immunoassay to evaluate the release of helical peptide 620-633 from the alpha1 chain of type I collagen. RESULTS: Naringenin was non-toxic at the highest concentration used (50 microg/ml). Naringenin (10, 25 and 50 microg/ml) significantly inhibited osteoclastogenesis (by 29 +/- 5, 57 +/- 8 and 96 +/- 1%, respectively). Naringenin also markedly inhibited the secretion of interleukin (IL)-1alpha (by 59%), IL-23 (by 87%) and monocyte chemoattractant protein-1 (by 58%). Lastly, naringenin (10, 25 and 50 microg/ml) significantly decreased the release of helical peptide 620-633, an indicator of bone resorption activity (by 44 +/- 0.5, 73 +/- 0.5 and 86 +/- 1%, respectively). CONCLUSIONS: Naringenin can inhibit human osteoclastogenesis and osteoclastic bone resorption. It thus holds promise as a therapeutic or preventive agent for bone-related diseases such as periodontitis.

Potential oral health benefits of cranberry.

In the past decade, cranberry extracts have been attracting ever-growing attention by dental researchers. The potential benefits of cranberry components in reducing oral diseases, including dental caries and periodontitis, are discussed in this review. A non-dialysable cranberry fraction enriched in high molecular weight polyphenols has very promising properties with respect to cariogenic and periodontopathogenic bacteria, as well as to the host inflammatory response and enzymes that degrade the extracellular matrix. Cranberry components are potential anti-caries agents since they inhibit acid production, attachment, and biofilm formation by Streptococcus mutans. Glucan-binding proteins, extracellular enzymes, carbohydrate production, and bacterial hydrophobicity, are all affected by cranberry components. Regarding periodontal diseases, the same cranberry fraction inhibits host inflammatory responses, production, and activity of enzymes that cause the destruction of the extracellular matrix, biofilm formation, and adherence of Porphyromonas gingivalis, and proteolytic activities and coaggregation of periodontopathogens. The above-listed effects suggest that cranberry components, especially those with high molecular weight, could serve as bioactive molecules for the prevention and/or treatment of oral diseases.