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

DOI： 10.1016/j.archoralbio.2022.105497

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Language：English  

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

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

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

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

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

Macrolides are used to treat various infectious diseases, including periodontitis. Furthermore, macrolides are known to have immunomodulatory effects; however, the underlying mechanism of their action remains unclear. DEL-1 has emerged as an important factor in homeostatic immunity and osteoclastogenesis. Specifically, DEL-1 is downregulated in periodontitis tissues. Therefore, in the present study, we investigated whether the osteoclastogenesis inhibitory effects of erythromycin (ERM) are mediated through upregulation of DEL-1 expression. We used a ligature-induced periodontitis model in C57BL/6Ncrl wild-type or DEL-1-deficient mice and in vitro cell-based mechanistic studies to investigate how ERM inhibits alveolar bone resorption. As a result of measuring alveolar bone resorption and gene expression in the tooth ligation model, ERM treatment reduced bone loss by increasing DEL-1 expression and decreasing the expression of osteoclast-related factors in wild-type mice. In DEL-1-deficient mice, ERM failed to suppress bone loss and gene expression of osteoclast-related factors. In addition, ERM treatment downregulated osteoclast differentiation and calcium resorption in in vitro experiments with mouse bone marrow-derived macrophages. In conclusion, ERM promotes the induction of DEL-1 in periodontal tissue, which may regulate osteoclastogenesis and decrease inflammatory bone resorption. These findings suggest that ERM may exert immunomodulatory effects in a DEL-1-dependent manner.

DOI： 10.3390/antibiotics10030312

Web of Science

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

BACKGROUND: Sulfated vizantin, a recently developed immunostimulant, has also been found to exert antibiofilm properties. It acts not as a bactericide, but as a detachment-promoting agent by reducing the biofilm structural stability. This study aimed to investigate the mechanism underlying this activity and its species specificity using two distinct ex vivo oral biofilm models derived from human saliva. RESULTS: The biofilm, composed mainly of the genus Streptococcus and containing 50 μM of sulfated vizantin, detached significantly from its basal surface with rotation at 500 rpm for only 15 s, even when 0.2% sucrose was supplied. Expression analyses for genes associated with biofilm formation and bacterial adhesion following identification of the Streptococcus species, revealed that a variety of Streptococcus species in a cariogenic biofilm showed downregulation of genes encoding glucosyltransferases involved in the biosynthesis of water-soluble glucan. The expression of some genes encoding surface proteins was also downregulated. Of the two quorum sensing systems involved in the genus Streptococcus, the expression of luxS in three species, Streptococcus oralis, Streptococcus gordonii, and Streptococcus mutans, was significantly downregulated in the presence of 50 μM sulfated vizantin. Biofilm detachment may be facilitated by the reduced structural stability due to these modulations. As a non-specific reaction, 50 μM sulfated vizantin decreased cell surface hydrophobicity by binding to the cell surface, resulting in reduced bacterial adherence. CONCLUSION: Sulfated vizantin may be a candidate for a new antibiofilm strategy targeting the biofilm matrix while preserving the resident microflora.

DOI： 10.1186/s12866-020-02033-w

PubMed

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

Streptococcus pneumoniae is often isolated from patients with community-acquired pneumonia. Antibiotics are the primary line of treatment for pneumococcal pneumonia; however, rising antimicrobial resistance is becoming more prevalent. Hinokitiol, which is isolated from trees in the cypress family, has been demonstrated to exert antibacterial activity against S. pneumoniae in vitro regardless of antimicrobial resistance. In this study, the efficacy of hinokitiol was investigated in a mouse pneumonia model. Male 8-week-old BALB/c mice were intratracheally infected with S. pneumoniae strains D39 (antimicrobial susceptible) and NU4471 (macrolide resistant). After 1 h, hinokitiol was injected via the tracheal route. Hinokitiol significantly decreased the number of S. pneumoniae in the bronchoalveolar lavage fluid (BALF) and the concentration of pneumococcal DNA in the serum, regardless of whether bacteria were resistant or susceptible to macrolides. In addition, hinokitiol decreased the infiltration of neutrophils in the lungs, as well as the concentration of inflammatory cytokines in the BALF and serum. Repeated hinokitiol injection at 18 h intervals showed downward trend in the number of S. pneumoniae in the BALF and the concentration of S. pneumoniae DNA in the serum with the number of hinokitiol administrations. These findings suggest that hinokitiol reduced bacterial load and suppressed excessive host immune response in the pneumonia mouse model. Accordingly, hinokitiol warrants further exploration as a potential candidate for the treatment of pneumococcal pneumonia.

DOI： 10.1371/journal.pone.0240329

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

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

Macrolide antibiotics exert anti-inflammatory effects; however, little is known regarding their immunomodulatory mechanisms. In this study, using two distinct mouse models of mucosal inflammatory disease (LPS-induced acute lung injury and ligature-induced periodontitis), we demonstrated that the anti-inflammatory action of erythromycin (ERM) is mediated through upregulation of the secreted homeostatic protein DEL-1. Consistent with the anti-neutrophil recruitment action of endothelial cell-derived DEL-1, ERM inhibited neutrophil infiltration in the lungs and the periodontium in a DEL-1-dependent manner. Whereas ERM (but not other antibiotics such as josamycin and penicillin) protected against lethal pulmonary inflammation and inflammatory periodontal bone loss, these protective effects of ERM were abolished in Del1-deficient mice. By interacting with the growth hormone secretagogue receptor (GHSR) and activating JAK2 in human lung microvascular endothelial cells, ERM induced C/EBPβ-dependent DEL-1 transcription, which was mediated by MAPK p38. Moreover, ERM reversed IL-17-induced inhibition of DEL-1 transcription, in a manner that was not only dependent on JAK2 but also on PI3K/AKT signaling. As DEL-1 levels are severely reduced in inflammatory conditions and with aging, the ability of ERM to upregulate DEL-1 may be a novel approach for the treatment of inflammatory and aging-related diseases.

DOI： 10.1172/jci.insight.136706

PubMed

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVE: The overall objective of this study was to investigate the effects of hinokitiol on periodontal bone loss in a murine model of experimental periodontitis and evaluate the anti-inflammatory activity of hinokitiol in vitro. DESIGN: Periodontitis was induced by tying a silk ligature around the maxillary second molar of mice for 8 days. Hinokitiol was injected once a day for 7 days into the palatal gingiva of the ligated molar. Periodontal bone loss was then assessed morphometrically in the maxillary second molar, and the number of tartrate-resistant acid phosphatase positive multinucleated giant cells around the molar was quantified. The bacterial load of the silk ligature was calculated by counting the number of colony-forming units, while the transcription levels of proinflammatory cytokine-related genes in the palatal gingiva were evaluated by real-time qPCR. The activity of hinokitiol against LPS-induced transcription of proinflammatory genes in RAW 264.7 macrophages was also examined. RESULTS: Local treatment with hinokitiol significantly inhibited the alveolar bone loss and osteoclast differentiation induced by tooth ligation. In addition, hinokitiol treatment decreased the oral bacterial load of the silk ligature and downregulated the mRNA levels of inflammatory cytokine-related genes, both in vitro and in vivo. CONCLUSION: The results indicated that hinokitiol exhibits antibacterial and anti-inflammatory activity and exerts a protective effect against periodontitis.

DOI： 10.1016/j.archoralbio.2020.104679

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DOI： 10.1111/1348-0421.12688

PubMed

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Aggregatibacter actinomycetemcomitans is considered to be associated with periodontitis. Leukotoxin (LtxA), which destroys leukocytes in humans, is one of this bacterium's major virulence factors. Amounts of neutrophil elastase (NE), which is normally localized in the cytoplasm of neutrophils, are reportedly increased in the saliva of patients with periodontitis. However, the mechanism by which NE is released from human neutrophils and the role of NE in periodontitis is unclear. In the present study, it was hypothesized that LtxA induces NE release from human neutrophils, which subsequently causes the breakdown of periodontal tissues. LtxA-treatment did not induce significant cytotoxicity against human gingival epithelial cells (HGECs) or human gingival fibroblasts (HGFs). However, it did induce significant cytotoxicity against human neutrophils, leading to NE release. Furthermore, NE and the supernatant from LtxA-treated human neutrophils induced detachment and death of HGECs and HGFs, these effects being inhibited by administration of an NE inhibitor, sivelestat. The present results suggest that LtxA mediates human neutrophil lysis and induces the subsequent release of NE, which eventually results in detachment and death of HGECs and HGFs. Thus, LtxA-induced release of NE could cause breakdown of periodontal tissue and thereby exacerbate periodontitis.

DOI： 10.1111/1348-0421.12672

PubMed

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

OBJECTIVE: Food-derived peptides have been reported to exhibit antibacterial activity against periodontal pathogenic bacteria. However, no effect has been shown on inflammation and bone resorption in periodontal pathology. The overall objective of the current study was to investigate how rice peptides influence biological defense mechanisms against periodontitis-induced inflammatory bone loss, and identify their novel functions as a potential anti-inflammatory drug. DESIGN: The expression of inflammatory and osteoclast-related molecules was examined in mouse macrophage-derived RAW 264.7 cell cultures using qPCR. Subsequently, the effect of these peptides on inflammatory bone loss in mouse periodontitis was examined using a mouse model of tooth ligation. Briefly, periodontal bone loss was induced for 7 days in mice by ligating the maxillary second molar and leaving the contralateral tooth un-ligated (baseline control). The mice were microinjected daily with the peptide in the gingiva until the day before euthanization. One week after the ligation, TRAP-positive multinucleated cells (MNCs) were enumerated from five random coronal sections of the ligated sites in each mouse. RESULTS: Rice peptides REP9 and REP11 significantly inhibited transcription activity of inflammatory and osteoclast-related molecules. Local treatment with the rice peptides, in mice subjected to ligature-induced periodontitis, inhibited inflammatory bone loss, explaining the decreased numbers of osteoclasts in bone tissue sections. CONCLUSION: Therefore, these data suggested that the rice peptides possess a protective effect against periodontitis.

DOI： 10.1016/j.archoralbio.2018.11.021

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

Vaccination is an effective strategy to prevent pneumococcal diseases. Currently, licensed vaccines include the pneumococcal polysaccharide vaccine (PPSV) and the pneumococcal conjugate vaccine (PCV), which target some of the most common of the 94 serotypes of S. pneumoniae based on their capsular composition. However, it has been reported that PPSV is not effective in children aged less than 2 years old and PCV induces serotype replacement, which means that the pneumococcal population has changed following widespread introduction of these vaccines, and the non-vaccine serotypes have increased in being the cause of invasive pneumococcal disease. Therefore, it is important that there is development of novel pneumococcal vaccines to either replace or complement current polysaccharide-based vaccines. Our previous study suggested that S. pneumoniae releases elongation factor Tu (EF-Tu) through autolysis followed by the induction of proinflammatory cytokines in macrophages via toll-like receptor 4, that may contribute to the development of pneumococcal diseases. In this study, we investigated the expression of EF-Tu in various S. pneumoniae strains and whether EF-Tu could be an antigen candidate for serotype-independent vaccine against pneumococcal infection. Western blotting and flow cytometry analysis revealed that EF-Tu is a common factor expressed on the surface of all pneumococcal strains tested, as well as intracellularly. In addition, we demonstrate that immunization with recombinant (r) EF-Tu induced the production of inflammatory cytokines and the IgG1 and IgG2a antibodies in mice, and increased the CD4+ T-cells proportion in splenocytes. We also reveal that anti-EF-Tu serum increased the phagocytic activity of mouse peritoneal macrophages against S. pneumoniae infection, independent of their serotypes. Finally, our results indicate that mice immunized with rEF-Tu were significantly and non-specifically protected against lethal challenges with S. pneumoniae serotypes (2 and 15A). Therefore, pneumococcal EF-Tu could be an antigen candidate for the serotype-independent vaccine against pneumococcal infection.

DOI： 10.1016/j.vaccine.2018.11.015

PubMed

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Excessive activation of neutrophils results in the release of neutrophil elastase (NE), which leads to lung injury in severe pneumonia. Previously, we demonstrated a novel immune subversion mechanism involving microbial exploitation of this NE ability, which eventually promotes disruption of the pulmonary epithelial barrier. In the present study, we investigated the effect of NE on host innate immune response. THP-1-derived macrophages were stimulated with heat-killed Streptococcus pneumoniae or lipopolysaccharide in the presence or absence of NE followed by analysis of toll-like receptor (TLR) and cytokine expression. Additionally, the biological significance of NE was confirmed in an in vivo mouse intratracheal infection model. NE downregulated the gene transcription of multiple cytokines in THP-1-derived macrophages through the cleavage of TLRs and myeloid differentiation factor 2. Additionally, NE cleaved inflammatory cytokines and chemokines. In a mouse model of intratracheal pneumococcal challenge, administration of an NE inhibitor significantly increased proinflammatory cytokine levels in bronchoalveolar lavage fluid, enhanced bacterial clearance, and improved survival rates. Our work indicates that NE subverts the innate immune response and that inhibition of this enzyme may constitute a novel therapeutic option for the treatment of pneumococcal pneumonia.

DOI： 10.3389/fimmu.2018.00732

PubMed

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Streptococcus pneumoniae is a leading cause of bacterial pneumonia. Our previous study suggested that S. pneumoniae autolysis-dependently releases intracellular pneumolysin, which subsequently leads to lung injury. In this study, we hypothesized that pneumococcal autolysis induces the leakage of additional intracellular molecules that could increase the pathogenicity of S. pneumoniae. Liquid chromatography tandem-mass spectrometry analysis identified that chaperone protein DnaK, elongation factor Tu (EF-Tu), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were released with pneumococcal DNA by autolysis. We demonstrated that recombinant (r) DnaK, rEF-Tu, and rGAPDH induced significantly higher levels of interleukin-6 and tumor necrosis factor production in peritoneal macrophages and THP-1-derived macrophage-like cells via toll-like receptor 4. Furthermore, the DNA-binding activity of these proteins was confirmed by surface plasmon resonance assay. We demonstrated that pneumococcal DnaK, EF-Tu, and GAPDH induced the production of proinflammatory cytokines in macrophages, and might cause host tissue damage and affect the development of pneumococcal diseases.

DOI： 10.1016/j.cellimm.2018.01.006

PubMed

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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：新潟歯学会  

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Language：Japanese  

J-GLOBAL

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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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Presentation type：Oral presentation (general)  

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Language：Japanese  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：English   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Oral presentation (general)  

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