Language：English   Publishing type：Research paper (scientific journal)  

The aim of this study was to examine the effect of adjunct local minocycline administration on the microbiological parameters of subgingival plaque samples in the residual periodontal pockets. Ten chronic periodontitis patients under a supportive periodontal therapy regimen were recruited. After subgingival debridement, either 2% minocycline gel, Periocline™, (Test Group) or a placebo (Control Group) was administered to the selected sites once a week for three weeks. Subgingival plaque was collected at baseline, and at four weeks and eight weeks. The microbiological composition was analyzed by 16S ribosomal RNA sequencing. In the Test Group, α-diversity (evenness) decreased compared to the baseline (p = 0.005) and was lower compared to the control group at four weeks (p = 0.003). The microbial community composition between the two groups was significantly different at four weeks (p = 0.029). These changes were attributable to a decrease in the bacteria associated with periodontitis and an increase in the bacteria associated with periodontal health. Additionally, the improvement in bleeding on probing continued at eight weeks; however, there were little microbial effects of 2% minocycline gel observed at eight weeks. The control group demonstrated no change throughout the eight-week experimental period. Thus, local minocycline administration can change the subgingival microbial community of residual periodontal pockets.

DOI： 10.3390/dj8040123

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Language：English   Publisher：ELSEVIER SCI LTD  

DOI： 10.1016/j.heliyon.2019.e01210

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Pro-protein convertase subtilisin/kexin type 9 (PCSK9), a secreted serine protease, regulates serum low-density lipoprotein (LDL) cholesterol levels by targeting the degradation of LDL receptor (LDLR) in the liver. Although previous reports describe elevated levels of PCSK9 in patients with periodontitis, the mechanisms that trigger this increase in serum PCSK9 levels and induce the related inflammatory response remain unclear. In an unc93b1-deficient mouse of Porphyromonas gingivalis infection, nucleic acid antigen recognition via Toll-like receptors was found to promote PCSK9 production, suggesting an indirect role for tumor necrosis factor-α as an inducer of PCSK9 in contrast to that reported in previous studies. Furthermore, PCSK9 production was independent of the TIR domain-containing adapter-inducing interferon-β-dependent signaling pathway. These results indicate that changes in LDLR expression precede an increase in the serum PCSK9 level in the context of an infectious disease such as periodontitis.

DOI： 10.1016/j.heliyon.2018.e01111

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Language：English   Publishing type：Research paper (scientific journal)  

Objectives: Several serum biomarkers have been reported to increase in periodontitis patients as possible mediators linking periodontal inflammation to systemic diseases. However, the relationship between periodontitis and urine biomarkers is still unclear. The aim of this cross-sectional study was to investigate potential urine biomarkers of periodontitis in a Japanese population. Materials and Methods: This study included 108 male subjects, and microbiological and clinical parameters were evaluated as a periodontitis marker. The correlation between nine urine biomarkers (typically used to diagnose kidney disease) and periodontal parameters was analyzed. Based on the findings, β2-microglobulin (β2-MG) and neutrophil gelatinase-associated lipocalin (NGAL) were selected for comparison and multivariate regression analysis, and the Kruskal-Wallis test followed by Bonferroni correction was used to identify differences in their concentrations between the three periodontitis groups (severe, moderate, and no/mild periodontitis). Results: β2-MG and NGAL exhibited a significant correlation with clinical parameters of periodontitis. The prevalence of clinical parameters such as bleeding on probing and number of sites with probing depth (PD) ≥ 6 mm were greater in the β2-MG high group (≥300 μg/g creatinine) than in the normal group (P=0.017 and 0.019, respectively). Multivariate regression analysis indicated that the number of sites with PD ≥ 6 mm was independently associated with urine β2-MG. Moreover, the number of sites with the clinical attachment level (CAL) ≥ 6 mm was greater in the NGAL high group (highest quartile) (P=0.041). Multivariate regression analysis showed that the number of sites with CAL ≥ 6 mm was associated independently with urine NGAL. Finally, β2-MG was significantly higher in the severe periodontitis subjects compared to the no/mild periodontitis subjects. Conclusion: The significant association between urine β2-MG or NGAL and periodontitis was revealed. These biomarkers can potentially be used to screen for or diagnose periodontitis. This trial is registered with the UMIN Clinical Trials Registry UMIN000013485.

DOI： 10.1155/2019/1394678

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Blackwell Munksgaard  

Background and Objectives: Previous reports suggest that several serum biomarkers play roles in the pathogenesis, inflammatory response, and oxidative stress in periodontitis caused by bacterial infections, linking chronic periodontitis to atherosclerotic vascular disease (ASVD). The aim of this preliminary study was to investigate, in a Japanese cross-sectional community survey, potential serum biomarkers of periodontitis that are associated with ASVD and chronic periodontitis. Material and Methods: The study cohort included a total of 108 male subjects who underwent annual health examinations. Serum biomarkers (high-sensitivity C-reactive protein [hs-CRP], proprotein convertase subtilisin/kexin type 9 [PCSK9], interleukin-6, tumor necrosis factor-α, soluble CD14, myeloperoxidase, matrix metalloproteinase-3, adiponectin, total bilirubin [TBIL], and serum lipids) were analyzed to determine their association (if any) with periodontal parameters. Aortic stiffness was evaluated using the brachial-ankle aortic pulse wave velocity (PWV) index and the cardio-ankle vascular index (CAVI). Results: The concentrations of PCSK9 and hs-CRP were increased (P =.001 and.042, respectively), and the concentration of TBIL was decreased (P =.046), in subjects with periodontal disease (determined as a probing depth of ≥4 mm in at least one site) compared with periodontally healthy subjects. The ratio of low-density lipoprotein cholesterol (LDL-C) to high-density lipoprotein cholesterol and the concentrations of triglycerides, remnant-like particles-cholesterol, and oxidized LDL were elevated in subjects with periodontal disease compared with periodontally healthy subjects (P =.038,.007,.002, and.049, respectively). Multivariate regression analyses indicated that the number of sites with a pocket depth of ≥4 mm was associated with the concentration of PCSK9 and inversely associated with the concentration of TBIL independently (standardized β =.243, P =.040
standardized β = −.443, P =.0002
respectively). Analysis of receiver operating characteristic curves of PCSK9 indicated moderate accuracy for predicting the presence of disease sites (probing depth ≥ 4 mm) (area under the curve = 0.740). No significance in the values of PWV and CAVI was observed between subjects with periodontal disease and periodontally healthy subjects. Conclusion: In Japanese male subjects, the concentrations of serum PCSK9 and TBIL were correlated with periodontal parameters. Moreover, PCSK9 could be a candidate biomarker for diagnosing chronic periodontitis, and may also have potential to evaluate the risk for periodontitis to cause ASVD. Longitudinal studies of larger populations are necessary to confirm the exact association of periodontitis with increased serum PCSK9 and decreased TBIL.

DOI： 10.1111/jre.12533

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Periodontitis has been implicated as a risk factor for metabolic disorders such as type 2 diabetes, atherosclerotic vascular diseases, and non-alcoholic fatty liver disease. Although bacteremias from dental plaque and/or elevated circulating inflammatory cytokines emanating from the inflamed gingiva are suspected mechanisms linking periodontitis and these diseases, direct evidence is lacking. We hypothesize that disturbances of the gut microbiota by swallowed bacteria induce a metabolic endotoxemia leading metabolic disorders. To investigate this hypothesis, changes in the gut microbiota, insulin and glucose intolerance, and levels of tissue inflammation were analysed in mice after oral administration of Porphyromonas gingivalis, a representative periodontopathogens. Pyrosequencing revealed that the population belonging to Bacteroidales was significantly elevated in P. gingivalis-administered mice which coincided with increases in insulin resistance and systemic inflammation. In P. gingivalis-administered mice blood endotoxin levels tended to be higher, whereas gene expression of tight junction proteins in the ileum was significantly decreased. These results provide a new paradigm for the interrelationship between periodontitis and systemic diseases.

DOI： 10.1038/srep04828

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Background and Objective: T and B cells are known to be involved in the disease process of periodontitis. However, the role of natural killer T cells in the pathogenesis of periodontitis has not been clarified.
Materials and Methods: To examine the role of these cells, C57BL/6J (wild-type), CD1d(-/-) and alpha-galactosylceramide (alpha GC)-stimulated wild-type mice were orally infected with Porphyromonas gingivalis strain W83.
Results: Apart from CD1d(-/-) mice, the level of alveolar bone resorption was elevated by the infection and was further accelerated in alpha GC-stimulated mice. The infection induced elevated levels of serum amyloid A and P. gingivalis-specific IgG in the sera, although the degree of elevation was much smaller in the CD1d(-/-) mice. Infection-induced RANKL elevation was only observed in aGC-stimulated mice. Although the cytokines produced by splenocytes were mainly T-helper 1 type in wild-type mice, those in alpha GC-stimulated mice were predominantly T-helper 2 type. In the liver, the infection demonstrated no effect on the gene expression for interferon-gamma, interleukin-4 and RANKL except alpha GC-stimulated mice in which the infection upregulated the gene expressions.
Conclusion: This study is the first to show that natural killer T cells upregulated systemic and local inflammatory responses induced by oral infection with P. gingivalis, thereby contributing to the progression of alveolar bone resorption.

DOI： 10.1111/jre.12080

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BIOMED CENTRAL LTD  

Background: Periodontal disease is suggested to increase the risk of atherothrombotic disease by inducing dyslipidemia. Recently, we demonstrated that proprotein convertase subtilisin/kexin type 9 (PCSK9), which is known to play a critical role in the regulation of circulating low-density lipoprotein (LDL) cholesterol levels, is elevated in periodontitis patients. However, the underlying mechanisms of elevation of PCSK9 in periodontitis patients are largely unknown. Here, we explored whether Porphyromonas gingivalis, a representative periodontopathic bacterium, -induced inflammatory response regulates serum PCSK9 and cholesterol levels using animal models.
Methods: We infected C57BL/6 mice intraperitoneally with Porphyromonas gingivalis, a representative strain of periodontopathic bacteria, and evaluated serum PCSK9 levels and the serum lipid profile. PCSK9 and LDL receptor (LDLR) gene and protein expression, as well as liver X receptors (Lxrs), inducible degrader of the LDLR (Idol), and sterol regulatory element binding transcription factor (Srebf)2 gene expression, were examined in the liver.
Results: P. gingivalis infection induced a significant elevation of serum PCSK9 levels and a concomitant elevation of total and LDL cholesterol compared with sham-infected mice. The LDL cholesterol levels were significantly correlated with PCSK9 levels. Expression of the Pcsk9, Ldlr, and Srebf2 genes was upregulated in the livers of the P. gingivalis-infected mice compared with the sham-infected mice. Although Pcsk9 gene expression is known to be positively regulated by sterol regulatory element binding protein (SREBP)2 (human homologue of Srebf2), whereas Srebf2 is negatively regulated by cholesterol, the elevated expression of Srebf2 found in the infected mice is thought to be mediated by P. gingivalis infection.
Conclusions: P. gingivalis infection upregulates PCSK9 production via upregulation of Srebf2, independent of cholesterol levels. Further studies are required to elucidate how infection regulates Srebf2 expression and subsequently influences lipid metabolism.

DOI： 10.1186/1476-511X-11-121

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Background and Objective: Periodontal infection affects atherosclerotic diseases, such as coronary heart diseases. Mouse models have revealed that oral infection with Porphyromonas gingivalis induces changes in inflammatory-and lipid metabolism-related gene expression, regardless of the development of atherosclerotic lesions. However, the serum protein expression profile in the oral infection model has not been investigated. The present study aimed to analyse the effect of oral infection with P. gingivalis on the expression levels of multiple cytokines in the serum in apolipoprotein E-deficient mice by using a cytokine antibody array. Material and Methods: C57BL/ 6. KOR-Apoe shl mice were orally infected with P. gingivalis five times at 3 day intervals and were then killed. Splenocytes were isolated and analysed for proliferative activity and immunoglobulin G (IgG) production in response to in vitro restimulation with P. gingivalis. The expression levels of various cytokines in the sera were analysed using a mouse antibody array glass chip. Results: Splenocytes from P. gingivalis-infected mice demonstrated significantly greater proliferation and IgG production in response to P. gingivalis compared with those from sham-infected mice. Antibody array analysis revealed the selective upregulation of matrix metalloproteinase 3, intercellular adhesion molecule 1, insulin-like growth factor binding protein 2 and chemokine (C-X-C motif) ligand 7 and the downregulation of interleukin-17, tumor necrosis factor-a and L-selectin. Conclusion: These data demonstrate that oral infection with P. gingivalis induces alterations in systemic cytokine production. These cytokines could play roles in the development not only of periodontitis but also of atherosclerosis.

DOI： 10.1111/j.1600-0765.2011.01441.x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Background: Periodontal disease increases the risk of atherothrombotic disease, and high concentrations of low density lipoprotein (LDL) cholesterol are considered to be involved: however, the underlying mechanisms are largely unknown. Recent studies demonstrated that proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a critical role in circulating LDL cholesterol concentrations. The aim of the present study is to analyze serum PCSK9 concentrations and their relation to lipoprotein concentrations in periodontitis patients.
Methods: Sera were obtained from 40 periodontitis patients and 30 control subjects. PCSK9 concentrations, high-sensitivity C-reactive protein (hs-CRP), IL-6, TNF-alpha and Porphyromonas gingivalis antibodies were measured by ELISA, and lipid profiles were determined by a commercial laboratory.
Results: Periodontitis patients demonstrated significantly higher serum antibody titer to P. gingivalis and hs-CRP concentrations than control subjects, suggesting infection with P. gingivalis and a systemic inflammatory response. PCSK9 concentrations in periodontitis patients were significantly higher than those in control subjects. However, the concentrations of total and LDL cholesterols were not significantly different between periodontitis patients and control subjects. Moreover, no correlations were observed between PCSK9 concentrations and lipid profiles.
Conclusion: Periodontal infection upregulates PCSK9 production. However, further studies are required to elucidate how periodontal infection affects PCSK9 concentrations and subsequent lipid metabolism. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cca.2011.09.023

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PUBLIC LIBRARY SCIENCE  

Background: Recent studies have suggested that periodontal disease increases the risk of atherothrombotic disease. Atherosclerosis has been characterized as a chronic inflammatory response to cholesterol deposition in the arteries. Although several studies have suggested that certain periodontopathic bacteria accelerate atherogenesis in apolipoprotein E-deficient mice, the mechanistic link between cholesterol accumulation and periodontal infection-induced inflammation is largely unknown.
Methodology/Principal Findings: We orally infected C57BL/6 and C57BL/6. KOR-Apoe(shl) (B6.Apoeshl) mice with Porphyromonas gingivalis, which is a representative periodontopathic bacterium, and evaluated atherogenesis, gene expression in the aorta and liver and systemic inflammatory and lipid profiles in the blood. Furthermore, the effect of lipopolysaccharide (LPS) from P. gingivalis on cholesterol transport and the related gene expression was examined in peritoneal macrophages. Alveolar bone resorption and elevation of systemic inflammatory responses were induced in both strains. Despite early changes in the expression of key genes involved in cholesterol turnover, such as liver X receptor and ATP-binding cassette A1, serum lipid profiles did not change with short-term infection. Long-term infection was associated with a reduction in serum high-density lipoprotein (HDL) cholesterol but not with the development of atherosclerotic lesions in wild-type mice. In B6.Apoeshl mice, long-term infection resulted in the elevation of very low-density lipoprotein (VLDL), LDL and total cholesterols in addition to the reduction of HDL cholesterol. This shift in the lipid profile was concomitant with a significant increase in atherosclerotic lesions. Stimulation with P. gingivalis LPS induced the change of cholesterol transport via targeting the expression of LDL receptor-related genes and resulted in the disturbance of regulatory mechanisms of the cholesterol level in macrophages.
Conclusions/Significance: Periodontal infection itself does not cause atherosclerosis, but it accelerates it by inducing systemic inflammation and deteriorating lipid metabolism, particularly when underlying hyperlidemia or susceptibility to hyperlipidemia exists, and it may contribute to the development of coronary heart disease.

DOI： 10.1371/journal.pone.0020240

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publisher：(一社)日本医療情報学会  

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Language：Japanese   Publisher：(NPO)日本歯周病学会  

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Language：Japanese   Publisher：(公財)腸内細菌学会  

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Language：Japanese   Publisher：(公財)日本ビフィズス菌センター  

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Language：Japanese   Publisher：新潟歯学会  

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Language：Japanese   Publisher：(NPO)日本歯周病学会  

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Language：Japanese   Publisher：(NPO)日本歯科保存学会  

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Language：Japanese   Publisher：(NPO)日本歯周病学会  

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Language：Japanese   Publisher：(NPO)日本歯科保存学会  

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Language：Japanese   Publisher：(NPO)日本歯科保存学会  

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Language：Japanese   Publisher：(NPO)日本歯周病学会  

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Language：Japanese   Publisher：(NPO)日本歯周病学会  

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