Daisuke Hinode

Relationship between Campylobacter rectus and periodontal status during pregnancy

INTRODUCTION In a previous study, we showed that the growth of Campylobacter rectus is stimulated by the presence of female sex hormones in the culture medium. In the present study, we examined the relationship between C. rectus levels in the saliva and the periodontal status of pregnant women. METHODS Unstimulated whole saliva was collected from 22 pregnant and 15 non-pregnant women. Periodontal pocket depth (PD) and bleeding on probing (BOP) were recorded. A quantitative real-time polymerase chain reaction was performed to determine the concentrations of suspected periodontopathogenic bacteria in the saliva samples. In addition, the concentration of estradiol in the saliva samples was measured by enzyme immunoassay. RESULTS The average age, number of teeth, and total number of bacteria in the saliva of subjects in both groups were similar. The percentage of sites with a PD = 4 mm and the salivary estradiol concentrations were significantly higher in pregnant women than in non-pregnant women. In addition, the percentage of BOP sites and the C. rectus levels in the saliva of the pregnant women tended to be higher than in non-pregnant women, although these differences were not statistically significant. There were positive correlations between C. rectus levels and estradiol concentrations, and between C. rectus levels and the percentage of sites with PD = 4 mm in the pregnant women. CONCLUSION These results indicate that C. rectus levels are higher in the oral flora of pregnant women and that this may be associated with increased salivary estradiol concentrations. This may contribute to periodontal disease progression during pregnancy.

PKR-mediated degradation of STAT1 regulates osteoblast differentiation.

The double-stranded RNA-dependent protein kinase (PKR) plays a critical role in various biological responses including antiviral defense, cell differentiation, apoptosis, and tumorigenesis. In this study, we investigated whether PKR could affect the post-translational modifications of STAT1 protein and whether these modifications regulate osteoblast differentiation. We demonstrated that PKR was necessary for the ubiquitination of STAT1 protein. The expressions of bone-related genes such as type I collagen, integrin binding sialoprotein, osteopontin, and osterix were suppressed in osteoblasts lacking PKR activity. In contrast, the expressions of interleukin-6 and matrix metalloproteinases 8 and 13 increased in PKR-mutated osteoblasts. The expression and degradation of STAT1 protein were regulated by PKR in a SLIM-dependent pathway. Inhibition of SLIM by RNA interference resulted in the decreased activity of Runx2 in osteoblasts. Stimulation of interleukin-6 expression and suppression of alkaline phosphatase activity were regulated through by SLIM-dependent pathway. However, expressions of bone-related genes and MMPs were regulated by SLIM-independent pathway. Our present results suggest that the aberrant accumulation of STAT1 protein induced by loss of PKR regulate osteoblast differentiation through both SLIM/STAT1-dependent and -independent pathways.

Generation of plasma kinin by three types of protease isolated from Porphyromonas gingivalis 381

Three types of protease (A, B and C) isolated from the culture supernatant of Porphyromonas gingivalis 381 had peculiar activities on kinin generation from high molecular-weight kininogen in vitro. Protease C released bradykinin from the kininogen in a reaction mixture containing 2 mM dithiothreitol, but A and B did not. However, the activity of degrading bradykinin was much stronger in protease A and B than in C. These findings suggest that only protease C shows plasma kallikrein activity.

Purification and Characterization of Arginine Carboxypeptidase Produced by Porphyromonas gingivalis

ABSTRACT Arginine carboxypeptidase was isolated from the cytoplasm of Porphyromonas gingivalis 381 and purified by DEAE-Sephacel column chromatography, followed by high-performance liquid chromatography on DEAE-5PW and TSK G2000SWXL. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme revealed the presence of three major bands at 42, 33, and 32 kDa with identical N-terminal sequences. By Western blotting analysis and immunoelectron microscopy, the arginine carboxypeptidase was found to be widely distributed in the cytoplasm and on the surface of the outer membrane. The open reading frame corresponding to the N-terminal amino acids of the arginine carboxypeptidase was detected by a search of the sequence of the P. gingivalis W83 genome. This sequence showed homology with mammalian carboxypeptidases (M, N, and E/H) and included a zinc-binding region signature, suggesting that the enzyme is a member of the zinc carboxypeptidase family. The purified enzyme was inhibited by EGTA, o-phenanthroline, dl-2-mercaptomethyl-3-guanidinoethylthiopropanoic acid, and some metal ions, such as Cu2+, Zn2+, and Cd2+. On the other hand, Co2+ activated the enzyme. The enzyme released arginine and/or lysine from biologically active peptides containing these amino acids at the C terminus but did not cleave substrates when proline was present at the penultimate position. These results indicate that the arginine carboxypeptidase produced by P. gingivalis is an exo type of metallocarboxypeptidase. This enzyme may function to release arginine in collaboration with an arginine aminopeptidase, e.g., Arg-gingipain, to obtain specific amino acids from host tissues during the growth of P. gingivalis.

A general procedure for the isolation of heat-shock proteins from periodontopathogenic bacteria

Abstract The isolation of heat-shock proteins (HSP) from whole cells of Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Bacteroides forsythus , which are recognized as periodontopathogens, was performed by affinity chromatography on adenosine 5′-triphosphate-agarose followed by preparative polyacrylamide gel electrophoresis under denaturing conditions. Analysis of the final material by silver nitrate staining of SDS-PAGE gels and Western immunoblotting using a commercial polyclonal antibody against HSP60 from Synechococcus sp. revealed homogenous protein preparations corresponding to GroEL-like proteins with apparent molecular mass of 68 kDa ( P. gingivalis ), 64 kDa ( A. actinomycetemcomitans ) and 67 kDa ( B. forsythus ). A second HSP was also isolated from P. gingivalis and B. forsythus , and recognized as a DnaK-like protein by immunoblotting with polyclonal antibody against DnaK (HSP70) from Escherichia coli . Our HSP isolation procedure is rapid and simple, and the purified proteins obtained may be used to determine their homology with other HSP previously characterized and to raise antibodies.

Levels of salivary stress markers in patients with anxiety about halitosis

OBJECTIVE To investigate the relationship between salivary stress markers and mental stress states in patients complaining of oral malodour. The utility of the salivary stress markers in assessment of mental conditions of those patients was also investigated. DESIGN The study population included 74 patients, aged 20-59 years, who complained of oral malodour and were referred to the Breath Odor Clinic at Tokushima University Hospital. Patients were classified into two groups, genuine halitosis (GH) and psychosomatic halitosis (PH), according to the results of organoleptic rating measurement. All patients were subjected to examination by the Cornell Medical Index (CMI) Health Questionnaire. Resting saliva was collected and levels of salivary IgA, cortisol and chromogranin A were determined by ELISA. Twenty-three volunteers not complaining of halitosis were included as the control group. Kruskal-Wallis test and Mann-Whitneys U-test were used for statistical analysis. RESULTS A significant increase was observed in the concentrations of salivary cortisol in the PH group as compared with GH and control groups (p<0.05). Concentrations of IgA and chromogranin A in saliva were not significantly different among the three groups. In addition, higher salivary cortisol concentrations were found in CMI scale III and IV (tendency towards neurosis) than in scale I and II (normal) (p<0.05). Since salivary cortisol reflects a status of chronic stress condition, psychosomatic halitosis might be closely related to this state of chronic stress. CONCLUSIONS Determination of cortisol levels in saliva may provide useful information for evaluating the mental status of patients complaining of halitosis.

Effects of Japanese traditional herbal medicines (Kampo) on growth and virulence properties of Porphyromonas gingivalis and viability of oral epithelial cells.

Abstract Context: Kampos, commonly used in Japanese traditional medicine, are standardized herbal mixtures that have been used for centuries to treat a variety of ailments. We hypothesized that Kampos may have unidentified properties that may be beneficial in periodontitis, an inflammatory disease affecting the tooth-supporting tissues. Objective: The aim of our study was to investigate various Kampos and their natural ingredients for their effects on Porphyromonas gingivalis growth, adherence to epithelial cells and proteinase activity. In addition, their effects on oral epithelial cell viability were evaluated. Materials and methods: Growth inhibition of P. gingivalis by various Kampos and their natural ingredients was evaluated by a microdilution broth assay method. Their effects on P. gingivalis proteinase activity and adherence to oral epithelial cells were determined by fluorometric assays. The cytotoxicity of test compounds towards oral epithelial cells was evaluated by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] test. Results: Of the 27 Kampos tested, 7 were found to inhibit the growth of P. gingivalis. The lowest minimal inhibitory concentration (MIC) (250 µg/ml) was obtained with TJ-113. Analysis of the composition of the seven active Kampos showed that they contain Chinese rhubarb as a common ingredient. Therefore, additional growth inhibitory assays on P. gingivalis were carried out with purified anthraquinones known to be present in rhubarb. Aloe-emodin and rhein possessed the strongest antibacterial effects towards P. gingivalis with an MIC of 0.78 µg/ml. The seven Kampos containing rhubarb and purified anthraquinones also exhibited the capacity to decrease the adherence of P. gingivalis to oral epithelial cells and to reduce its proteinase activity. The most important anti-adherence effect of Kampo was obtained with TJ-126; at 250 µg/ml it reduced adherence of P. gingivalis to epithelial cells by 83%. Purified anthraquinones were found to be less active than Kampos. Kampo TJ-113 was found to be the most effective for inhibition of gelatin degradation (49% inhibition at 62.5 µg/ml). Again, purified anthraquinones inhibited gelatin degradation to a lesser extent. Lastly, none of the tested compounds showed cytotoxicity towards oral epithelial cells at the effective concentrations. Conclusion: Kampos containing rhubarb and its anthraquinone derivatives may represent promising molecules for controlling periodontal diseases through their capacity to inhibit P. gingivalis growth and virulence properties.

The Kampo Medicine Rokumigan Possesses Antibiofilm, Anti-Inflammatory, and Wound Healing Properties

Periodontal diseases, which are inflammatory diseases of bacterial origin affecting the tooth-supporting tissues, are characterized by inflammation and destruction of gingival connective tissue and alveolar bone, and may lead to tooth loss. The aim of the study was to investigate Rokumigan, a Kampo Japanese traditional medicine made of six different plants, for its capacity to prevent biofilm formation by Fusobacterium nucleatum, to inhibit interleukin-6 (IL-6) and interleukin-8 (IL-8) secretion by mucosal cells, and to promote wound healing in a fibroblast model. Using a microplate colorimetric assay, Rokumigan prevented biofilm formation by F. nucleatum, while it had no effect on bacterial growth. Rokumigan inhibited IL-6 secretion in both epithelial cells and fibroblasts stimulated with lipopolysaccharide. However, it caused no significant inhibition of IL-8 secretion by both cell types. Rokumigan significantly increased proliferation and migration of gingival fibroblasts in a wound healing assay. In conclusion, the Kampo formulation Rokumigan, through suppression of biofilm formation by F. nucleatum, inhibition of IL-6 secretion by gingival epithelial cells and fibroblasts, and promotion of wound healing in a fibroblast model, may have potential application for periodontal diseases.

PKR plays a positive role in osteoblast differentiation by regulating GSK-3β activity through a β-catenin-independent pathway.

Double-stranded RNA-dependent protein kinase (PKR) is involved in various cellular functions. We previously reported that PKR regulates osteoblast differentiation, but the specific mechanisms by which this occurs remain unclear. In this study, we investigated the role of PKR in Glycogen synthase kinase 3β (GSK-3β) regulation of osteoblast differentiation. Lithium chloride (LiCl), a GSK-3β inhibitor, increased GSK-3β phosphorylation in MC3T3-E1 and MG-63 cells. LiCl also inhibited Runx2 and expression of its regulated genes, causing inhibition of Alkaline phosphatase activity and mineralization. LiCl injection to the calvaria in mice suppressed bone formation. Further, GSK-3β phosphorylation was increased in osteoblasts, by Akt-independent mechanisms, in which PKR was constitutively inactivated. A PKR inhibitor, 2-aminopurine, also induced GSK-3β phosphorylation in MC3T3-E1 and MG-63 cells. Further, Runx2 and its regulated genes were inhibited in PKR-inactivated osteoblasts, and differentiation was suppressed through a β-catenin-independent pathway. PKR positively regulates the differentiation of osteoblasts by mediating GSK-3β activity through a β-catenin-independent pathway.

Interaction between PKR and PACT mediated by LPS‐inducible NF‐κB in human gingival cells

The double‐stranded RNA‐dependent protein kinase (PKR) is a serine/threonine kinase expressed constitutively in mammalian cells. PKR is activated upon virus infection by double‐stranded RNA (dsRNA), and plays a critical role in host antiviral defense mechanisms. PKR is also known to regulate various biological responses, including cell differentiation and apoptosis. However, whether PKR is involved in the progress of periodontitis is not clear. The present study explained the phosphorylation of PKR by LPS in the human gingival cell line, Sa3. Expression of genes encoding LPS receptors was detected in Sa3 cells and treatment of cells with 1 µg/mL LPS for 6 h caused PKR phosphorylation. LPS elevated the expression of the protein activator of PKR (PACT) mRNA and protein, followed by the enhanced association between PACT and PKR within 3 h. In addition, LPS treatment induced the translocation of NF‐κB to the nucleus after 30 min, and inhibition of NF‐κB decreased the PACT–PKR interaction induced by LPS. The level of pro‐inflammatory cytokine mRNA, including interleukin‐6 (IL‐6) and tumor necrosis factor alpha (TNFα), appeared within 45 min and reached at the maximal levels by 90 min after the addition of LPS. This induction of pro‐inflammatory cytokines was not affected by RNAi‐mediated silencing of PKR and a pharmacological inhibitor of PKR, whereas the inhibition of NF‐κB decreased it. These results indicated that LPS induces PKR phosphorylation and the PACT–PKR association in Sa3 cells. Our results also suggest that NF‐κB is involved in the PACT–PKR interaction and the production of pro‐inflammatory cytokines in periodontitis. J. Cell. Biochem. 113: 165–173, 2012.