18β‐Glycyrrhetinic acid inhibits periodontitis via glucocorticoid‐independent nuclear factor‐κB inactivation in interleukin‐10‐deficient mice

Sasaki H, Suzuki N, AlShwaimi E, Xu Y, Battaglino R, Morse L, Stashenko P. 18β‐Glycyrrhetinic acid inhibits periodontitis via glucocorticoid‐independent nuclear factor‐κB inactivation in interleukin‐10‐deficient mice. J Periodont Res 2010; 45: 757–763. © 2010 John Wiley & Sons A/S Background and Objective: 18β‐Glycyrrhetinic acid (GA) is a natural anti‐inflammatory compound derived from licorice root extract (Glycyrrhiza glabra). The effect of GA on experimental periodontitis and its mechanism of action were determined in the present study. Material and Methods: Periodontitis was induced by oral infection with Porphyromonas gingivalis W83 in interleukin‐10‐deficient mice. The effect of GA, which was delivered by subcutaneous injections in either prophylactic or therapeutic regimens, on alveolar bone loss and gingival gene expressions was determined on day 42 after initial infection. The effect of GA on lipopolysaccharide (LPS)‐stimulated macrophages, T cell proliferation and osteoclastogenesis was also examined in vitro. Results: 18β‐Glycyrrhetinic acid administered either prophylactically or therapeutically resulted in a dramatic reduction of infection‐induced bone loss in interleukin‐10‐deficient mice, which are highly disease susceptible. Although GA has been reported to exert its anti‐inflammatory activity via downregulation of 11β‐hydroxysteroid dehydrogenase‐2 (HSD2), which converts active glucocorticoids to their inactive forms, GA did not reduce HSD2 gene expression in gingival tissue. Rather, in glucocorticoid‐free conditions, GA potently inhibited LPS‐stimulated proinflammatory cytokine production and RANKL‐stimulated osteoclastogenesis, both of which are dependent on nuclear factor‐κB. Furthermore, GA suppressed LPS‐ and RANKL‐stimulated phosphorylation of nuclear factor‐κB p105 in vitro. Conclusion: These findings indicate that GA inhibits periodontitis by inactivation of nuclear factor‐κB in an interleukin‐10‐ and glucocorticoid‐independent fashion.     

Effects of three γ‐alkylidene‐γ‐lactams on the formation of multispecies biofilms

This study evaluated the inhibitory effects of lactams on Streptococcus mutans, Enterococcus faecalis, and Candida glabrata multispecies biofilm formation. γ‐Alkylidene‐γ‐lactams 1, 2, and 3 [solubilized in 3.5% dimethyl sulfoxide (DMSO)] were tested. Glass coverslips were conditioned with either the lactams or 3.5% DMSO (control) for 1 h, inoculated with microbial cultures, and incubated for 48 h. To assess the effect of the lactams on biofilm formation, the following parameters were determined: the biofilm biomass (by both crystal violet staining and protein determination); the amount of insoluble polysaccharides of the extracellular matrix; and the number of viable and total cells [by both colony‐forming unit counting and quantitative real‐time PCR (qPCR)]. Data were analysed using one‐way anova and post‐hoc Tukey tests. Lactams 1, 2, and 3 promoted a statistically significant reduction in the amount of biofilm biomass, but only lactam 3 resulted in a statistically significant reduction in the number of attached viable E. faecalis. Both total protein content and the amount of extracellular polysaccharides decreased significantly. The effects of γ‐alkylidene‐γ‐lactams 1, 2, and 3 on the inhibition of multispecies biofilm formation were evident by their ability to reduce the amount of protein and extracellular polysaccharides.     

Cloning and expression of α‐d‐glucosidase and N‐acetyl‐β‐glucosaminidase from the periodontal pathogen,Tannerella forsythensis (Bacteroides forsythus)

Screening a genomic library of Tannerella forsythensis (Bacteroides forsythus), using synthetic substrates conjugated to a fluorogen, 4‐methylumbelliferone identified two glycosidase genes, which encode α‐d ‐glucosidase and N‐acetyl‐β‐d ‐glucosaminidase, respectively. The α‐d ‐glucosidase has a M_r of 81,141 and is homologous to an α‐d ‐glucosidase from Bacteroidesthetaiotaomicron. The N‐acetyl‐β‐d ‐glucosaminidase has a M_r of 87,787 and is homologous to an N‐acetyl‐β‐d ‐glucosaminidase in Porphyromonasgingivalis W83.     

Tumor Necrosis Factor‐α Induces Matrix Metalloproteinases‐3, ‐10, and ‐13 in Human Periodontal Ligament Cells

Background: Various biologic mediators, including matrix metalloproteinases (MMPs), that are implicated in periodontal tissue breakdown can be induced by cytokines. MMPs are known to degrade periodontal ligament attachment, and bone matrix proteins and tissue inhibitors of metalloproteinase (TIMPs) inhibit the activity of MMPs. The aim of this study is to investigate the effect of tumor necrosis factor (TNF)‐α on the expression of MMPs in human periodontal ligament (PDL) cells in vitro and establish which MMPs are expressed specifically in response to that stimulus. Methods: Cultured PDL cells were stimulated with TNF‐α and analyzed with an MMP antibody array. Real‐time polymerase chain reaction (PCR), enzyme‐linked immunosorbent assay (ELISA), and western blot with cell lysate and zymography were used to measure messenger RNA (mRNA) and protein levels of MMP‐3, ‐10, and ‐13. To examine TNF receptor (TNFR) expression, PDL cells were examined by flow cytometry, and expression of MMP‐3, ‐10, and ‐13 was observed after blocking the TNFR with an antagonist. Results from real‐time PCR, ELISA, and western blot were analyzed by paired t test. Results: The antibody array showed that the protein most strongly upregulated by TNF‐α stimulation was MMP‐3, followed by MMP‐13 and MMP‐10. The TNF‐α receptor blocker specifically inhibited expression of MMP‐3 and ‐13. In addition, TNF‐α increased levels of MMP mRNAs in MMP‐3, ‐13, and ‐10 (in decreasing order). However, ELISAs showed that MMP‐13 was the most upregulated protein, followed by MMP‐10 and MMP‐3. Western blotting indicated that TNF‐α increased MMP‐3 and ‐13 levels but had no significant effect on the level of MMP‐10, and zymography showed that TNF‐α increased the activities of all forms of MMP‐3 and ‐13, but MMP‐10 was not detected. Flow cytometry demonstrated that the majority of PDL cells expressed TNFR1. Conclusions: TNF‐α (10 ng/mL) upregulates levels of MMP‐3, ‐10, and ‐13 in human PDL cells. These results suggest that these proteins play an important role in the inflammation of PDLs.     

Cost‐effectiveness of an experimental caries‐control regimen in a 3.4‐yr randomized clinical trial among 11–12‐yr‐old Finnish schoolchildren

The aim of this study was to assess the cost‐effectiveness of an experimental caries‐control regimen in a randomized clinical trial (RCT) conducted in Pori, Finland, in 2001–2005. Children (n = 497) who were 11–12 yr of age and had at least one active initial caries lesion at baseline were studied. The children in the experimental group (n = 250) were offered an individually designed patient‐centered regimen for caries control. The children in the control group (n = 247) received standard dental care. Furthermore, the whole population was exposed to continuous community‐level oral health promotion. Individual costs of treatment procedures and outcomes (DMFS increment score) for the follow‐up period of 3.4 yr were calculated for each child in both groups. The incremental cost‐effectiveness ratio was €34.07 per averted DMF surface. The experimental regimen was more effective, and also more costly. However, the total costs decreased year after year, and for the last 2 yr the experimental regimen was less expensive than the standard dental care. The experimental regimen would probably have been more cost‐effective than standard dental care if the follow‐up period had been longer, the regimen less comprehensive, and/or if dental nurses had conducted the preventive procedures.     

Carbon monoxide releasing molecule‐3 inhibits concurrent tumor necrosis factor‐α‐ and interleukin‐1β‐induced expression of adhesion molecules on human gingival fibroblasts

Song H, Zhao H, Qu Y, Sun Q, Zhang F, Du Z, Liang W, Qi Y, Yang P. Carbon monoxide releasing molecule‐3 inhibits concurrent tumor necrosis factor‐α‐ and interleukin‐1β‐induced expression of adhesion molecules on human gingival fibroblasts. J Periodont Res 2011; 46: 48–57. © 2010 John Wiley & Sons A/S Background and Objective: Carbon monoxide releasing molecule‐3 (CORM‐3) is a newly reported compound that has shown anti‐inflammatory effects in a number of cells. In this study, we aimed to investigate the influence of CORM‐3 on concurrent tumor necrosis factor‐α (TNF‐α)‐ and interleukin (IL)‐1β‐induced expression of adhesion molecules on human gingival fibroblasts (HGF). Material and Methods: HGF were cultured from the explants of normal gingival tissues. Cells were costimulated with TNF‐α and IL‐1β in the presence or absence of CORM‐3 for different periods of time. The expression of adhesion molecules, nuclear factor‐kappaB (NF‐κB) and phosphorylated p38 was studied using western blotting. RT‐PCR was applied to check the expression of the adhesion molecules at the mRNA level. The activity of NF‐κB was analysed using a reporter gene assay. Results: CORM‐3 inhibited the up‐regulation of intercellular adhesion molecule 1, vascular cell adhesion molecule 1 and endothelial leukocyte adhesion molecule in HGF after costimulation with TNF‐α and IL‐1β, which resulted in the decreased adhesion of peripheral blood mononuclear cells to these cells. Sustained activation of the NF‐κB pathway by costimulation with TNF‐α and IL‐1β was suppressed by CORM‐3, which was reflected by a reduced NF‐κB response element‐dependent luciferase activity and decreased nuclear NF‐κB‐p65 expression. CORM‐3 inhibited MAPK p38 phosphorylation in response to stimulation with proinflammatory cytokines. Conclusion: The results of this study bode well for the application of CORM‐3 as an anti‐inflammatory agent to inhibit NF‐κB activity and to suppress the expression of adhesion molecules on HGF, which suggests a promising potential for CORM‐3 in the treatment of inflammatory periodontal disease.