Occurrence of Porphyromonas gingivalis and Tannerella forsythensis in periodontally diseased and healthy subjects

Nanochemistry of gold: from surface engineering to dental healthcare applications

Advancements in nanochemistry have led to the development of engineered gold nanostructures (GNSs) with remarkable potential for a variety of dental healthcare applications. These innovative nanomaterials offer unique properties and functionalities that can significantly improve dental diagnostics, treatment, and overall oral healthcare applications. This review provides an overview of the latest advancements in the design, synthesis, and application of GNSs for dental healthcare applications. Engineered GNSs have emerged as versatile tools, demonstrating immense potential across different aspects of dentistry, including enhanced imaging and diagnosis, prevention, bioactive coatings, and targeted treatment of oral diseases. Key highlights encompass the precise control over GNSs' size, crystal structure, shape, and surface functionalization, enabling their integration into sensing, imaging diagnostics, drug delivery systems, and regenerative therapies. GNSs, with their exceptional biocompatibility and antimicrobial properties, have demonstrated efficacy in combating dental caries, periodontitis, peri-implantitis, and oral mucosal diseases. Additionally, they show great promise in the development of advanced sensing techniques for early diagnosis, such as nanobiosensor technology, while their role in targeted drug delivery, photothermal therapy, and immunomodulatory approaches has opened new avenues for oral cancer therapy. Challenges including long-term toxicity, biosafety, immune recognition, and personalized treatment are under rigorous investigation. As research at the intersection of nanotechnology and dentistry continues to thrive, this review highlights the transformative potential of engineered GNSs in revolutionizing dental healthcare, offering accurate, personalized, and minimally invasive solutions to address the oral health challenges of the modern era.

Co-occurrence of periodontal lesions and dental wear in incisor and masticatory teeth in two sheep flocks in Brazil

BACKGROUND

Periodontitis and tooth wear are multifactorial diseases with distinct etiopathogenesis that affect the health, feed efficiency and welfare of sheep.

METHODS

This study evaluated the co-occurrence of tooth wear and periodontal lesions in 129 ewes from two Brazilian flocks, clinically classified the lesions and presence of dental calculus, and identified potential pathogens in the dental biofilm of 63 ewes by polymerase chain reaction.

RESULTS

Of the 129 ewes included in the study, 75 presented periodontal lesions, while all animals presented tooth wear and dental calculus. Of the animals with periodontal lesions, 16.2% had lesions in incisor teeth and 52.7% in masticatory teeth. Regarding excessive tooth wear, 38.6% had severe wear on the incisor teeth and 89.1% on the masticatory teeth. Ewes older than 36 months had a higher frequency of periodontal lesions in incisor teeth (p < 0.001) and a greater amount of dental calculus (p < 0.001), but there was no association between tooth wear and animal age. Fusobacterium nucleatum, Tannerella forsythia and Fusobacterium necrophorum predominated in periodontal lesions.

LIMITATION

This study is limited by the small sample size and lack of diagnostic imaging to assess periodontal disease.

CONCLUSION

The co-occurrence of periodontal lesions and excessive dental wear involving both the incisor and masticatory teeth suggests that although the two diseases have different aetiologies, they likely have common risk factors.

Effects of nicotine and lipopolysaccharide stimulation on adhesion molecules in human gingival endothelial cells

Smoking is a risk factor for periodontitis, and the immune response of periodontal tissues in patients with periodontitis may be strongly affected by smoking. The purpose of this study was to elucidate the bioactivity and signal transduction of human gingival endothelial cells (HGECs) due to nicotinic stimulation using a cultured medium supplemented with lipopolysaccharide (LPS) as a model of periodontitis. HGECs were cultured in medium supplemented with LPS, nicotine, nicotine + LPS, and medium supplemented without nicotine or LPS (control). Cell proliferation was assessed using Alamar blue. Cytotoxicity was assessed by lactate dehydrogenase leakage. The expression of adhesion molecule-1 (ICAM-1, VCAM-1) was assessed by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay. The expression of nicotinic acetylcholine receptor (nAChR) subunits (α3, α5, α7, β2 and β4) was evaluated by RT-PCR. The involvement of p38 mitogen-activated protein kinase (p38MAPK) and protein kinase C (PKC) cell signaling pathways in ICAM-1 and VCAM-1 expression was investigated by RT-qPCR with specific inhibitors. HGECs stimulated with LPS, nicotine and nicotine + LPS showed inhibition of cell proliferation, increase of cell death, and increase of gene and protein expression of ICAM-1. Moreover, HGECs showed the presence of α5 and α7 nAChR subunits. The expression of ICAM-1 in HGECs stimulated with LPS, nicotine, and nicotine + LPS was significantly suppressed by p38MAPK inhibitor, but not by a PKC inhibitor. The nAChR subunits of HGECs are α5 and α7, and that HGECs stimulated with nicotine and LPS express ICAM-1 via p38MAPK pathway.

Hexokinase 2-mediated glycolysis supports inflammatory responses to Porphyromonas gingivalis in gingival fibroblasts

BACKGROUND

When infected with Porphyromonas gingivalis, gingival fibroblasts undergo metabolic reprogramming, and rely on aerobic glycolysis rather than oxidative phosphorylation for rapid energy replenishment. Hexokinases (HKs) are catalysts for glucose metabolism, and HK2 constitutes the major HK inducible isoform. The objective of this study is to determine whether HK2-mediated glycolysis promotes inflammatory responses in inflamed gingiva.

METHODS

Levels of glycolysis-related genes were assessed in normal and inflamed gingiva. Human gingival fibroblasts were harvested and infected with Porphyromonas gingivalis in order to mimic periodontal inflammation. 2-deoxy-d-glucose, an analogue of glucose, was used to block HK2-mediated glycolysis, while small interfering RNA was used to knock down HK2 expression. The mRNA and protein levels of genes were analyzed by real-time quantitative PCR and western blotting, respectively. HK2 activity and lactate production were assessed by ELISA. Cell proliferation was assessed by confocal microscopy. The generation of reactive oxygen species was assessed by flow cytometry.

RESULTS

Elevated expression of HK2 and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 was observed in the inflamed gingiva. P. gingivalis infection was shown to promote glycolysis in human gingival fibroblasts, as evidenced by increased gene transcription of HK2 and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3, cell glucose consumption, and HK2 activity. Inhibition and knockdown of HK2 resulted in reduced cytokine production, cell proliferation, and reactive oxygen species generation. Furthermore, P. gingivalis infection activated the hypoxia-inducible factor-1α signaling pathway, thus promoting HK2-mediated glycolysis and proinflammatory responses.

CONCLUSIONS

HK2-mediated glycolysis promotes inflammatory responses in gingival tissues, and therefore glycolysis can be targeted in order to inhibit the progression of periodontal inflammation.

Oral microbiome and risk of incident head and neck cancer: A nested case-control study

OBJECTIVES

This nested case-control study in the NIH-AARP Diet and Health Study was carried out to prospectively investigate the relationship of oral microbiome with head and neck cancer (HNC).

MATERIALS AND METHODS

56 incident HNC cases were identified, and 112 controls were incidence-density matched to cases. DNA extracted from pre-diagnostic oral wash samples was whole-genome shotgun metagenomic sequenced to measure the overall oral microbiome. ITS2 gene qPCR was used to measure the presence of fungi. ITS2 gene sequencing was performed on ITS2 gene qPCR positive samples. We computed taxonomic and functional alpha-diversity and beta-diversity metrics. The presence and relative abundance of groups of red-complex (e.g., Porphyromonas gingivalis) and/or orange-complex (e.g., Fusobacterium nucleatum) periodontal pathogens were compared between cases and controls using conditional logistic regression models and MiRKAT.

RESULTS

Participants with higher taxonomic microbial alpha-diversity had a non-statistically significant decreased risk of HNC. No case-control differences were found for beta diversity by MiRKAT model (all p > 0.05). A greater relative abundance of red-complex periodontal pathogens (OR = 0.51, 95 % CI = 0.26-1.00), orange-complex (OR = 0.38, 95 % CI = 0.18-0.83), and both complexes' pathogens (OR = 0.32, 95 % CI = 0.14-0.75), were associated with reduced risk of HNC. The presence of oral fungi was also strongly associated with reduced risk of HNC compared with controls (OR = 0.39, 95 % CI = 0.17-0.92).

CONCLUSION

Greater taxonomic alpha-diversity, the presence of oral fungi, and the presence or relative abundance of multiple microbial species, including the red- and orange-complex periodontal pathogens, were associated with reduced risk of HNC. Future studies with larger sample sizes are needed to evaluate these associations.

Identification of microbiological factors associated with periodontal health disparities

The present study aimed at identifying risk factors associated with periodontitis development and periodontal health disparities with emphasis on differential oral microbiota. The prevalence of periodontitis is recently rising dentate adults in the US, which presents a challenge to oral health and overall health. The risk of developing periodontitis is higher in African Americans (AAs), and Hispanic Americans (HAs) than in Caucasian Americans (CAs). To identify potentially microbiological determinations of periodontal health disparities, we examined the distribution of several potentially beneficial and pathogenic bacteria in the oral cavities of AA, CA, and HA study participants. Dental plaque samples from 340 individuals with intact periodontium were collected prior to any dental treatment, and levels of some key oral bacteria were quantitated using qPCR, and the medical and dental histories of participants were obtained retrospectively from axiUm. Data were analyzed statistically using SAS 9.4, IBM SPSS version 28, and R/RStudio version 4.1.2. Amongst racial/ethnic groups: 1) neighborhood medium incomes were significantly higher in the CA participants than the AA and the HA participants; 2) levels of bleeding on probing (BOP) were higher in the AAs than in the CAs and HAs; 3) Porphyromonas gingivalis levels were higher in the HAs compared to that in the CAs; 4) most P. gingivalis detected in the AAs were the fimA genotype II strain that was significantly associated with higher BOP indexes along with the fimA type IV strain. Our results suggest that socioeconomic disadvantages, higher level of P. gingivalis, and specific types of P. gingivalis fimbriae, particularly type II FimA, contribute to risks for development of periodontitis and periodontal health disparities.

Interleukin-34 Permits Porphyromonas gingivalis Survival and NF-κB p65 Inhibition in Macrophages

Interleukin-34 (IL-34) is a cytokine that supports the viability and differentiation of macrophages. An important cytokine for the development of epidermal immunity, IL-34 is present and plays a role in the immunity of the oral environment. IL-34 has been linked to inflammatory periodontal diseases, which involve innate phagocytes, including macrophages. Whether IL-34 can alter the ability of macrophages to effectively interact with oral microbes is currently unclear. Using macrophages derived from human blood monocytes with either the canonical cytokine colony-stimulating factor (CSF)1 or IL-34, we compared the ability of the macrophages to phagocytose, kill, and respond through the production of cytokines to the periodontal keystone pathogen Porphyromonas gingivalis. While macrophages derived from both cytokines were able to engulf the bacterium equally, IL-34 derived macrophages were much less capable of killing internalized P. gingivalis. Of the macrophage cell surface receptors known to interact with P. gingivalis, DC-SIGN was found to have the largest variation between IL-34 and CSF1-derived macrophages. We also found that upon interaction with P. gingivalis, IL-34 derived macrophages produced significantly less of the neutrophil chemotactic factor IL-8 than macrophages derived in the presence of CSF1. Mechanistically, we identified that levels of IL-8 corresponded with P. gingivalis survival and dephosphorylation of the major transcription factor NF-κB p65. Overall, we found that macrophages differentiated in the presence of IL-34, a dominant cytokine in the oral gingiva, have a reduced ability to kill the keystone pathogen P. gingivalis and may be susceptible to specific bacteria-mediated cytokine modification. This article is protected by copyright. All rights reserved.

Protease activities of vaginal Porphyromonas species disrupt coagulation and extracellular matrix in the cervicovaginal niche

Porphyromonas asaccharolytica and Porphyromonas uenonis are common inhabitants of the vaginal microbiome, but their presence has been linked to adverse health outcomes for women, including bacterial vaginosis and preterm birth. However, little is known about the pathogenesis mechanisms of these bacteria. The related oral opportunistic pathogen, Porphyromonas gingivalis, is comparatively well-studied and known to secrete numerous extracellular matrix-targeting proteases. Among these are the gingipain family of cysteine proteases that drive periodontal disease progression and hematogenic transmission to the placenta. In this study, we demonstrate that vaginal Porphyromonas species secrete broad-acting proteases capable of freely diffusing within the cervicovaginal niche. These proteases degrade collagens that are enriched within the cervix (type I) and chorioamniotic membranes (type IV), as well as fibrinogen, which inhibits clot formation. Bioinformatic queries confirmed the absence of gingipain orthologs and identified five serine, cysteine, and metalloprotease candidates in each species. Inhibition assays revealed that each species’ proteolytic activity can be partially attributed to a secreted metalloprotease with broad substrate specificity that is distantly related to the P. gingivalis endopeptidase PepO. This characterization of virulence activities in vaginal Porphyromonas species highlights their potential to alter the homeostasis of reproductive tissues and harm human pregnancy through clotting disruption, fetal membrane weakening, and premature cervical remodeling.

Computational Design of a Multi-Epitope Vaccine Against Porphyromonas gingivalis

Porphyromonas gingivalis is a Gram-negative pathogenic bacterium associated with chronic periodontitis. The development of a chimeric peptide-based vaccine targeting this pathogen could be highly beneficial in preventing oral bone loss as well as other severe gum diseases. We applied a computational framework to design a multi-epitope-based vaccine candidate against P. gingivalis. The vaccine comprises epitopes from subunit proteins prioritized from the P. gingivalis reference strain (P. gingivalis ATCC 33277) using several reported vaccine properties. Protein-based subunit vaccines were prioritized through genomics techniques. Epitope prediction was performed using immunoinformatic servers and tools. Molecular modeling approaches were used to build a putative three-dimensional structure of the vaccine to understand its interactions with host immune cells through biophysical techniques such as molecular docking simulation studies and binding free energy methods. Genome subtraction identified 18 vaccine targets: six outer-membrane, nine cytoplasmic membrane-, one periplasmic, and two extracellular proteins. These proteins passed different vaccine checks required for the successful development of a vaccine candidate. The shortlisted proteins were subjected to immunoinformatic analysis to map B-cell derived T-cell epitopes, and antigenic, water-soluble, non-toxic, and good binders of DRB1*0101 were selected. The epitopes were then modeled into a multi-epitope peptide vaccine construct (linked epitopes plus adjuvant) to enhance immunogenicity and effectively engage both innate and adaptive immunity. Further, the molecular docking approach was used to determine the binding conformation of the vaccine to TLR2 innate immune receptor. Molecular dynamics simulations and binding free energy calculations of the vaccine–TLR2 complex were performed to highlight key intermolecular binding energies. Findings of this study will be useful for vaccine developers to design an effective vaccine for chronic periodontitis pathogens, specifically P. gingivalis.

Protease inhibitor concentrations in the saliva of individuals experiencing oral dryness

Background

Oral dryness is a common symptom that may interfere with swallowing, chewing, and taste. The most common reason for oral dryness is hyposalivation. Some individuals experiencing oral dryness do not have hyposalivation, however, and the reverse is also true. Here, we focused on healthy individuals with a lower salivary flow rate and evaluated the relationship between the perception of oral dryness and salivary parameters to clarify the cause underlying the perception of oral dryness.

Methods

A total of 59 participants were divided into 2 groups with a lower or higher salivary flow rate according to the median salivary flow rate. In participants with a lower salivary flow rate, we assessed salivary bacterial counts, protease activities, protein concentrations, oral parameters, and the subjective perception of oral dryness.

Results

Protease activities and concentrations of protease inhibitors such as cystatin-D and cystatin-SA in the saliva of participants experiencing oral dryness were significantly higher and lower, respectively, than in those not experiencing oral dryness, even though no difference in the salivary flow rate was detected. Salivary cystatin-D and cystatin-SA concentrations correlated negatively with salivary protease activities.

Conclusions

The composition of salivary protease inhibitors and increased protease activities affect the subjective perception of oral dryness.

Effect of human secretory calcium-binding phosphoprotein proline-glutamine rich 1 protein on Porphyromonas gingivalis and identification of its active portions

The mouth environment comprises the second most significant microbiome in the body, and its equilibrium is critical in oral health. Secretory calcium-binding phosphoprotein proline-glutamine rich 1 (SCPPPQ1), a protein normally produced by the gingival epithelium to mediate its attachment to teeth, was suggested to be bactericidal. Our aim was to further explore the antibacterial potential of human SCPPPQ1 by characterizing its mode of action and identifying its active portions. In silico analysis showed that it has molecular parallels with antimicrobial peptides. Incubation of Porphyromonasgingivalis, a major periodontopathogen, with the full-length protein resulted in decrease in bacterial number, formation of aggregates and membrane disruptions. Analysis of SCPPPQ1-derived peptides indicated that these effects are sustained by specific regions of the molecule. Altogether, these data suggest that human SCPPPQ1 exhibits antibacterial capacity and provide new insight into its mechanism of action.

STAT1/SOCS1/3 Are Involved in the Inflammation-Regulating Effect of GAS6/AXL in Periodontal Ligament Cells Induced by Porphyromonas gingivalis Lipopolysaccharide In Vitro

Periodontitis involves chronic inflammation of the tissues around the teeth caused by plaque and the corresponding immune response. Growth arrest-specific protein 6 (GAS6) and AXL receptor tyrosine kinase (AXL) are known to be involved in inflammatory diseases, while signal transducer and activator of transcription-1 (STAT1) and suppressor of cytokine signaling (SOCS) are related to inflammatory processes. Moreover, miRNA34a directly targets AXL to regulate the AXL expression. However, the specific roles of GAS6 and AXL in periodontitis remain unclear. This study was designed to explore the effect and mechanism of AXL on the expression of inflammatory cytokines induced by Porphyromonas gingivalis lipopolysaccharide (P. gingivalis LPS) in human periodontal ligament cells (hPDLCs). The effects of different concentrations of P. gingivalis LPS on the expression of GAS6/AXL in hPDLCs were observed. Additionally, the effect of LPS on AXL was investigated by transfection of the miRNA34a inhibitor. AXL was knocked down or overexpressed to observe the release of inflammatory cytokines interleukin- (IL-) 8 and IL-6. The results showed that the expression levels of GAS6 and AXL decreased after P. gingivalis LPS infection. Transfection of a miR-34a inhibitor to hPDLCs demonstrated a role of miR-34a in the downregulation of AXL expression induced by LPS. Moreover, AXL knockdown or overexpression influencing the expression of IL-8 and IL-6 was investigated under LPS stimulation. AXL knockdown decreased the expression of STAT1 and SOCS1/3. Overall, these results demonstrate that AXL inhibits the expression of LPS-induced inflammatory cytokines in hPDLCs and that STAT1 and SOCS1/3 are involved in the regulation of inflammation by GAS6/AXL.

Periodontal Pathogens and Neuropsychiatric Health

Increasing evidence incriminates low-grade inflammation in cardiovascular, metabolic diseases, and neuropsychiatric clinical conditions, all important causes of morbidity and mortality. One of the upstream and modifiable precipitants and perpetrators of inflammation is chronic periodontitis, a polymicrobial infection with Porphyromonas gingivalis (P. gingivalis) playing a central role in the disease pathogenesis. We review the association between P. gingivalis and cardiovascular, metabolic, and neuropsychiatric illness, and the molecular mechanisms potentially implicated in immune upregulation as well as downregulation induced by the pathogen. In addition to inflammation, translocation of the pathogens to the coronary and peripheral arteries, including brain vasculature, and gut and liver vasculature has important pathophysiological consequences. Distant effects via translocation rely on virulence factors of P. gingivalis such as gingipains, on its synergistic interactions with other pathogens, and on its capability to manipulate the immune system via several mechanisms, including its capacity to induce production of immune-downregulating micro-RNAs. Possible targets for intervention and drug development to manage distal consequences of infection with P. gingivalis are also reviewed.

A systematic review and critical appraisal of metagenomic and culture studies in hidradenitis suppurativa

Hidradenitis suppurativa (HS), also known as acne inversa, is a chronic inflammatory skin disease with still largely unknown pathogenesis. While infectious organisms have been identified in lesions of the disease since the 1980s, questions remain over the role that bacteria and microbiome play. Recent studies using 16S ribosomal RNA gene sequencing and larger culture-based studies have begun to paint a clearer picture of the microbial world of HS. With this systematic review, we summarize all the work that has been done to date in HS bacteriology, analyse potential pitfalls and limitations of the current studies, and address future directions of investigation. This systematic review attempted to collate and analyse all bacteriology studies done to date. This review was prospectively registered with PROSPERO (1670769) performed in line with the PRISMA checklist. Twenty two studies were identified comprising 862 individual HS patients for culture studies and 206 HS patients for 16S rRNA gene sequencing studies. Methodology tended to be varied, with different sampling, culturing and sequencing methods as well as amount of analysis and stratification of patients. Bacteria identified as elevated in HS lesions in sequencing studies as well as grown from HS lesions in culture studies are identified and discussed. These primarily included the anerobic Gram-negative bacilli Prevotella, Porphyromonas and Fusibacterium, the Gram-positive bacilli Corynebacterium, and the Gram-positive cocci Staphylococcus, Streptococcus and Parvimonas. Potential interactions, as well as work in other disease models with related bacteria are also discussed. Areas of further investigation include in vitro studies of interactions between bacteria and keratinocytes, gut and oral microbiome studies and deep sequencing studies for virulence and phage factors.

Porphyromonas: A neglected potential key genus in human microbiomes

Anaerobes form a large part of microbial communities, and have begun to be specifically studied in both healthy and pathologic contexts. Porphyromonas is one of the top ten anaerobic taxa in the microbiome (anaerobiome) in healthy subjects. However, to date, most studies focused on the deleterious role of P. gingivalis, the most widely described species. Interestingly, targeted metagenomics reveals Porphyromonas other than gingivalis (POTG), highlighting other species such as P. catoniae or P. pasteri as potential biomarkers in disease progression or pathogen colonization susceptibility. From the sparse data, it appears that the Porphyromonas genus may also be a relevant target of investigation in several pulmonary diseases. Moreover, deciphering cutaneous, gastric and oral microbiomes hint that Porphyromonas may be a genus of interest in non-pulmonary diseases. This review aims to summarize the major data on POTG and to report their impact on the various human microbiomes in different clinical states.

In Situ Intraepithelial Localizations of Opportunistic Pathogens, Porphyromonas gingivalis and Filifactor alocis, in Human Gingiva

•

The gingival epithelium serves as a growth reservoir for opportunistic bacteria.

•

Intraepithelial P. gingivalis and F. alocis colonies are detected together in dysbiotic mucosa.

•

Increased metabolically active dual species can lead to higher microvasculature.

•

Invasion of intraepithelial microvessels leads to systemic pathogen dissemination.

Porphyromonas gingivalis and Filifactor alocis are fastidious oral pathogens and etiological agents associated with chronic periodontitis. Although previous studies showed increased levels of the two obligate anaerobic species in periodontitis patients, methodologies for this knowledge were primarily limited to sampling subgingival plaque, saliva, or gingival crevicular fluid. To evaluate the extent to which P. gingivalis and F. alocis may invade the periodontal tissues, an in situ cross-sectional study was comparatively conducted on the gingival biopsy specimens of patients diagnosed with periodontal health or chronic periodontitis. Immunostained tissue sections for each organism were imaged by Super-Resolution Confocal Scanning Microscopy to determine the relative presence and localization of target bacterial species. Fluorescence-in-situ-hybridization (FISH) coupled with species specific 16S rRNA method was utilized to confirm whether detected bacteria were live within the tissue. In periodontitis, P. gingivalis and F. alocis revealed similarly concentrated localization near the basement membrane or external basal lamina of the gingival epithelium. The presence of both bacteria was significantly increased in periodontitis vs. healthy tissue. However, P. gingivalis was still detected to an extent in health tissue, while only minimal levels of F. alocis were spotted in health. Additionally, the micrographic analyses displayed heightened formation of epithelial microvasculature containing significantly co-localized and metabolically active dual species within periodontitis tissue. Thus, this study demonstrates, for the first-time, spatial arrangements of P. gingivalis and F. alocis in both single and co-localized forms within the complex fabric of human gingiva during health and disease. It also exhibits critical visualizations of co-invaded microvascularized epithelial layer of the tissue by metabolically active P. gingivalis and F. alocis from patients with severe periodontitis. These findings collectively uncover novel visual evidence of a potential starting point for systemic spread of opportunistic bacteria during their chronic colonization in gingival epithelium.

Serum immunoglobulin G antibody titer to Fusobacterium nucleatum is associated with unfavorable outcome after stroke

Stroke can be a cause of death, while in non-fatal cases it is a common cause of various disabilities resulting from associated brain damage. However, whether a specific periodontal pathogen is associated with increased risk of unfavorable outcome after stroke remains unknown. We examined risk factors for unfavorable outcome following stroke occurrence, including serum antibody titers to periodontal pathogens. The enrolled cohort included 534 patients who had experienced an acute stroke, who were divided into favorable (n = 337) and unfavorable (n = 197) outcome groups according to modified ranking scale (mRS) score determined at 3 months after onset (favorable = score 0 or 1; unfavorable = score 2-6). The associations of risk factors with unfavorable outcome, including serum titers of IgG antibodies to 16 periodontal pathogens, were examined. Logistic regression analysis showed that the initial National Institutes of Health stroke scale score [odds ratio (OR) = 1·24, 95% confidence interval (CI) = 1·18-1·31, P < 0·001] and C-reactive protein (OR = 1·29, 95% CI = 1·10-1·51, P = 0·002) were independently associated with unfavorable outcome after stroke. Following adjustment with those, detection of the antibody for Fusobacterium nucleatum ATCC 10953 in serum remained an independent predictor of unfavorable outcome (OR = 3·12, 95% CI = 1·55-6·29, P = 0·002). Determination of the antibody titer to F. nucleatum ATCC 10953 in serum may be useful as a predictor of unfavorable outcome after stroke.

Gingimaps: Protein Localization in the Oral Pathogen Porphyromonas gingivalis

Porphyromonas gingivalis is an oral pathogen involved in the widespread disease periodontitis. In recent years, however, this bacterium has been implicated in the etiology of another common disorder, the autoimmune disease rheumatoid arthritis. Periodontitis and rheumatoid arthritis were known to correlate for decades, but only recently a possible molecular connection underlying this association has been unveiled. P. gingivalis possesses an enzyme that citrullinates certain host proteins and, potentially, elicits autoimmune antibodies against such citrullinated proteins. These autoantibodies are highly specific for rheumatoid arthritis and have been purported both as a symptom and a potential cause of the disease. The citrullinating enzyme and other major virulence factors of P. gingivalis, including some that were implicated in the etiology of rheumatoid arthritis, are targeted to the host tissue as secreted or outer-membrane-bound proteins. These targeting events play pivotal roles in the interactions between the pathogen and its human host. Accordingly, the overall protein sorting and secretion events in P. gingivalis are of prime relevance for understanding its full disease-causing potential and for developing preventive and therapeutic approaches. The aim of this review is therefore to offer a comprehensive overview of the subcellular and extracellular localization of all proteins in three reference strains and four clinical isolates of P. gingivalis, as well as the mechanisms employed to reach these destinations.

Immunological Pathways Triggered by Porphyromonas gingivalis and Fusobacterium nucleatum: Therapeutic Possibilities?

Porphyromonas gingivalis (P. gingivalis) and Fusobacterium nucleatum (F. nucleatum) are Gram-negative anaerobic bacteria possessing several virulence factors that make them potential pathogens associated with periodontal disease. Periodontal diseases are chronic inflammatory diseases of the oral cavity, including gingivitis and periodontitis. Periodontitis can lead to tooth loss and is considered one of the most prevalent diseases worldwide. P. gingivalis and F. nucleatum possess virulence factors that allow them to survive in hostile environments by selectively modulating the host's immune-inflammatory response, thereby creating major challenges to host cell survival. Studies have demonstrated that bacterial infection and the host immune responses are involved in the induction of periodontitis. The NLRP3 inflammasome and its effector molecules (IL-1β and caspase-1) play roles in the development of periodontitis. We and others have reported that the purinergic P2X7 receptor plays a role in the modulation of periodontal disease and intracellular pathogen control. Caspase-4/5 (in humans) and caspase-11 (in mice) are important effectors for combating bacterial pathogens via mediation of cell death and IL-1β release. The exact molecular events of the host's response to these bacteria are not fully understood. Here, we review innate and adaptive immune responses induced by P. gingivalis and F. nucleatum infections and discuss the possibility of manipulations of the immune response as therapeutic strategies. Given the global burden of periodontitis, it is important to develop therapeutic targets for the prophylaxis of periodontopathogen infections.

There's no place like OM: Vesicular sorting and secretion of the peptidylarginine deiminase of Porphyromonas gingivalis

The oral pathogen Porphyromonas gingivalis is one of the major periodontal agents and it has been recently hailed as a potential cause of the autoimmune disease rheumatoid arthritis. In particular, the peptidylarginine deiminase enzyme of P. gingivalis (PPAD) has been implicated in the citrullination of certain host proteins and the subsequent appearance of antibodies against citrullinated proteins, which might play a role in the etiology of rheumatoid arthritis. The aim of this study was to investigate the extracellular localization of PPAD in a large panel of clinical P. gingivalis isolates. Here we show that all isolates produced PPAD. In most cases PPAD was abundantly present in secreted outer membrane vesicles (OMVs) that are massively produced by P. gingivalis, and to minor extent in a soluble secreted state. Interestingly, a small subset of clinical isolates showed drastically reduced levels of the OMV-bound PPAD and secreted most of this enzyme in the soluble state. The latter phenotype is strictly associated with a lysine residue at position 373 in PPAD, implicating the more common glutamine residue at this position in PPAD association with OMVs. Further, one isolate displayed severely restricted vesiculation. Together, our findings show for the first time that neither the major association of PPAD with vesicles, nor P. gingivalis vesiculation per se, are needed for P. gingivalis interactions with the human host.

Prolyl hydroxylases positively regulated LPS-induced inflammation in human gingival fibroblasts via TLR4/MyD88-mediated AKT/NF-κB and MAPK pathways

OBJECTIVES

Prolyl hydroxylases (PHDs) play essential roles in oxygen-sensing system, whereas the effects of PHDs on inflammation have not been totally uncovered. Our study aimed to investigate the role of PHDs in lipopolysaccharide (LPS)-induced inflammation of human gingival fibroblasts (HGFs) and clarify the potential mechanisms.

MATERIALS AND METHODS

A pan hydroxylase inhibitor, dimethyloxallyl glycine (DMOG), and RNA interference were used to explore the role of PHDs in inflammation. Cytotoxic effect of DMOG was determined by cell-counting kit-8 and flow cytometry respectively. The secretion levels of IL-6 and IL-8 were assessed by ELISA. The mRNA levels of inflammatory cytokines, Toll-like receptor (TLR) 4 and MyD88 were evaluated by quantitative real-time PCR. The activation of NF-κB, mitogen-activated protein kinase (MAPK) and PI3K/AKT pathways were detected by western blot and the nuclear translocation of NF-κB p65 was examined by immunofluorescence. Downregulation of PHD1 and PHD2 was performed with siRNA transfection.

RESULTS

Dimethyloxallyl glycine inhibited LPS-induced inflammatory cytokine, TLR4 and MyD88 expression in gene level and the elevated secretion of IL-6 and IL-8 was also downregulated. Additionally, LPS-induced activation of NF-κB, MAPK and AKT pathways was abolished by DMOG treatment. Importantly, LPS-induced inflammatory cytokine expression was merely suppressed by PHD2 knockdown.

CONCLUSIONS

Prolyl hydroxylases acted as a positive regulator in LPS-induced inflammation of HGFs via TLR4/MyD88-mediated NF-κB, MAPK and AKT signalling pathways and PHD2 among three isoforms was principally responsible for the effects.

A Review of Evidence for a Therapeutic Application of Traditional Japanese Kampo Medicine for Oral Diseases/Disorders

Kampo medicines prescribed by specialized medical practitioners and Japanese physicians have gradually reemerged in Japan as alternatives to Western medications. Kampo formulations are composed of several plant extracts and, as such, the broad variety of phytochemicals they contain likely act synergistically to provide their beneficial effects. Kampo medicines have traditionally been prescribed for a number of health conditions, including chronic hepatitis, bronchial asthma, anemia, etc. The aim of this article is to review the beneficial effects of Kampos with respect to oral health. Pertinent papers published between 1970 and 2017 were retrieved by searching in PubMed, ScienceDirect, Web of Science, and Scopus using key words followed by evaluation of the relevant articles. In vitro studies have identified a number of properties that give credence to the potential of Kampos for treating or preventing oral diseases/disorders. Given their anti-microbial and anti-inflammatory properties, they may be promising agents for controlling periodontal diseases, oral mucositis, xerostomia, and drug-induced gingival overgrowth. Since some oral diseases have a complex etiology that involves microbial pathogens and the host immune response, agents with dual functionality such as Kampo phytochemicals may offer a therapeutic advantage.

Oral Biofilms from Symbiotic to Pathogenic Interactions and Associated Disease -Connection of Periodontitis and Rheumatic Arthritis by Peptidylarginine Deiminase

A wide range of bacterial species are harbored in the oral cavity, with the resulting complex network of interactions between the microbiome and host contributing to physiological as well as pathological conditions at both local and systemic levels. Bacterial communities inhabit the oral cavity as primary niches in a symbiotic manner and form dental biofilm in a stepwise process. However, excessive formation of biofilm in combination with a corresponding deregulated immune response leads to intra-oral diseases, such as dental caries, gingivitis, and periodontitis. Moreover, oral commensal bacteria, which are classified as so-called “pathobionts” according to a now widely accepted terminology, were recently shown to be present in extra-oral lesions with distinct bacterial species found to be involved in the onset of various pathophysiological conditions, including cancer, atherosclerosis, chronic infective endocarditis, and rheumatoid arthritis. The present review focuses on oral pathobionts as commensal and healthy members of oral biofilms that can turn into initiators of disease. We will shed light on the processes involved in dental biofilm formation and also provide an overview of the interactions of P. gingivalis, as one of the most prominent oral pathobionts, with host cells, including epithelial cells, phagocytes, and dental stem cells present in dental tissues. Notably, a previously unknown interaction of P. gingivalis bacteria with human stem cells that has impact on human immune response is discussed. In addition to this very specific interaction, the present review summarizes current knowledge regarding the immunomodulatory effect of P. gingivalis and other oral pathobionts, members of the oral microbiome, that pave the way for systemic and chronic diseases, thereby showing a link between periodontitis and rheumatoid arthritis.

Inflammasome and Oral Diseases

One of the main steps in the development of the life in the earth is multicellularity. It enables cell differentiation and the development of morphological structures within an organism and is an essential factor in how to recognize friendly cells that are part of the multicellular organism and which foreign organisms can be harmful. Recognition includes devices such as the major histocompatibility complex (MHC), and the pattern recognition receptors (PRRs). PRRs are a group of proteins expressed by cells of the innate immune system that identify two classes of products: pathogen-associated molecular patterns (PAMPs), related to microbial pathogens, and damage-associated molecular patterns (DAMPs), associated with cell components that are released during cell damage or death. All these activate the inflammasome, which is a multiprotein oligomer that includes caspase 1, PYCARD, NALP, and caspase 5 (also known as caspase 11 or ICH-3). It is responsible for activation of inflammatory processes and has been shown to induce cell pyroptosis, a programmed cell death distinct from apoptosis, and promotes the maturation of the inflammatory cytokines interleukin 1β (IL-1β) and interleukin 18 (IL-18). We review whether inflammasome is related to diseases that can occur in the oral cavity. The mouth is always a possible environment for the development of pathological conditions because of the wide variety of microorganisms. Small variations in the equilibrium of the oral flora can cause disorders that could affect the organism in a systemic form. We provide data on periodontal disease, candidiasis, herpes virus, oral cancer, caries, and other oral diseases. There are very few papers that study this issue; therefore, we need more investigation and publications about inflammatory molecular processes, and more specifically, related to the inflammasome complex.

Diode laser therapy in the management of chronic periodontitis - A clinico-microbiological study

Introduction

Chronic periodontitis (CP) is an infectious disease resulting in inflammation of the supporting tissues of the teeth with progressive attachment loss and bone loss. This study aimed to evaluate the effect of 980-nm diode laser, as an adjunct to scaling and root planing (SRP) in the management of CP.

Methodology

A total of 40 systemically healthy subjects diagnosed with CP were randomly assigned into two groups G1 (SRP and sham application of laser) and G2 (SRP and laser irradiation) with equal numbers in each. The levels of Porphyromonas gingivalis (Pg) were estimated from plaque samples using real-time polymerase chain reaction. Clinical and microbiological parameters were assessed at baseline, 4–6, and 12–14 weeks posttreatment in both groups.

Results

A gradual reduction in the levels of Pg and improvement in clinical parameters were observed from baseline to 4–6 and 12–14 weeks in both groups. However, the comparison between groups, although clinically relevant, was not found to be statistically significant.

Conclusion

Although a 980-nm diode laser may not have any added benefit compared with SRP, it may emerge as an effective non-surgical treatment option in advanced periodontitis with complex inaccessible subgingival niches where comprehensive periodontal care may not be feasible.

Study of Porphyromonas gingivalis in periodontal diseases: A systematic review and meta-analysis

Background: The mouth cavity hosts various types of anaerobic bacteria including Porphyromonas gingivalis, which causes periodontal inflammatory diseases. P. gingivalis is a gram-negative oral anaerobe and is considered as a main etiological factor in periodontal diseases. Several studies have reported a relationship between P. gingivalis in individuals with periodontal diseases and a critical role of this bacterium in the pathogenesis of periodontal diseases. The present study aimed at estimating this probability using a meta-analysis.

Methods: We searched several databases including PubMed, Scopus, Google Scholar, and Web of Science to identify case-control studies addressing the relationship between P. gingivalis with periodontal diseases. A total of 49 reports published from different countries from 1993 to 2014 were included in this study. I² (heterogeneity index) statistics were calculated to examine heterogeneity. Data were analyzed using STATA Version 11.

Results: After a detailed analysis of the selected articles, 49 case-control studies with 5924 individuals fulfilled the inclusion criteria for the meta-analysis. The healthy controls included 2600 healthy individuals with a Mean±SD age of 36.56±7.45 years. The periodontal diseases group included 3356 patients with a mean age of 43.62±8.35 years. There was a statistically significant difference between P. gingivalis in periodontal patients and healthy controls; 9.24 (95% CI: 5.78 to 14.77; P = 0.000). In the other word, there was a significant relationship between the presence of P. gingivalis and periodontal diseases.

Conclusion: Analyzing the results of the present study, we found a strong association between the presence of P. gingivalis and periodontal diseases. This result suggests that another research is needed to further assess this subject.

Dominant prevalence of Porphyromonas gingivalis fimA types I and IV in healthy Japanese children

Background/purpose

Porphyromonas gingivalis is a major causative agent of chronic periodontitis, whilst circumstances for acquisition of the bacterium remain to be elucidated. To examine prevalence of the bacterium harboring distinct fimA types in dental plaque of children, we established PCR procedures that are applicable for specimens with limited amounts. By this method, all six fimA types including type I and Ib were directly identified, and prevalence of fimA types and their frequency of guardian-child transmission in Japanese children were assessed.

Materials and methods

Genomic DNA was purified from dental plaque specimens of 132 periodontally healthy children (2-12 years old, 4.8 ± 0.2 years) and 19 mothers of resultant P. gingivalis-positive child subjects. PCR-based fimA genotyping was performed, and untypeable strains in the first PCR analysis were determined by a nested PCR.

Results

P. gingivalis was found in 15.2% of the subjects (2-10 years old, 5.1 ± 0.6 years), and the most prevalent types were I and IV (37.0% each), followed by Ib and III (11.1% each), and then II (7.4%). Seven (35.0%) of the 20 P. gingivalis-positive subjects had combined colonization of type I with other fimA types. In most cases, bacterial prevalence and fimA types in the children were distinct from those of their mothers, indicating that its maternal transmission was not significant.

Conclusion

These results suggest that colonization of non-disease-associated fimA types I and IV P. gingivalis to the oral cavity initiates from early childhood without showing any periodontal inflammation.

Persistent Exposure to Porphyromonas gingivalis Promotes Proliferative and Invasion Capabilities, and Tumorigenic Properties of Human Immortalized Oral Epithelial Cells

Recent epidemiological studies revealed a significant association between oral squamous cell carcinoma (OSCC) and Porphyromonas gingivalis, a major pathogen of periodontal disease. As a keystone pathogen of periodontitis, P. gingivalis is known not only to damage local periodontal tissues, but also to evade the host immune system and eventually affect systemic health. However, its role in OSCC has yet to be defined. To explore the underlying effect of chronic P. gingivalis infection on OSCC and to identify relevant biomarkers as promising targets for therapy and prevention, we established a novel model by exposing human immortalized oral epithelial cells (HIOECs) to P. gingivalis at a low multiplicity of infection (MOI) for 5–23 weeks. The P. gingivalis infected HIOECs were monitored for tumor biological alteration by proliferation, wound healing, transwell invasion, and gelatin zymography assays. Microarray and proteomic analyses were performed on HIOECs infected with P. gingivalis for 15 weeks, and some selected data were validated by quantitative real-time PCR and (or) western blot on cells infected for 15 and 23 weeks. Persistent exposure to P. gingivalis caused cell morphological changes, increased proliferation ability with higher S phase fraction in the cell cycle, and promoted cell migratory and invasive properties. In combining results of bioinformatics analyses and validation assays, tumor-related genes such as NNMT, FLI1, GAS6, lncRNA CCAT1, PDCD1LG2, and CD274 may be considered as the key regulators in tumor-like transformation in response to long-time exposure of P. gingivalis. In addition, some useful clinical biomarkers and novel proteins were also presented. In conclusion, P. gingivalis could promote tumorigenic properties of HIOECs, indicating that chronic P. gingivalis infection may be considered as a potential risk factor for oral cancer. The key regulators detected from the present model might be used in monitoring the development of OSCC with chronic periodontal infection.

Case of a cerebral abscess caused by Porphyromonas gingivalis in a subject with periodontitis

We report the case of a 65-year-old man presenting with generalised seizures after developing a right frontal brain abscess. Stereotactic aspiration and subsequent matrix assisted laser desorption/ionisation time-of-flight analyzer (MALDI-TOF) spectrometry revealed Porphyromonas gingivalis as the only causative anaerobe microorganism. Secondary incision and drainage was required due to neurological deterioration with increased dimensions of the abscess, intracranial pressure and formation of a subdural occipitoparietal empyema. Oral imaging was positive for apical periodontitis of multiple elements; therefore, the remaining dentition was removed. Targeted antibiotic treatment included intravenous ceftriaxone and ornidazole. The patient was discharged to our revalidation unit 59 days after admission to make a full recovery. To the best of our knowledge, this is the sixth reported case of P. gingivalis causing an intracranial abscess and the third case of a true intracerebral parenchymal abscess caused by this bacterium.

Human dental stem cells suppress PMN activity after infection with the periodontopathogens Prevotella intermedia and Tannerella forsythia

Periodontitis is characterized by inflammation associated with the colonization of different oral pathogens. We here aimed to investigate how bacteria and host cells shape their environment in order to limit inflammation and tissue damage in the presence of the pathogen. Human dental follicle stem cells (hDFSCs) were co-cultured with gram-negative P. intermedia and T. forsythia and were quantified for adherence and internalization as well as migration and interleukin secretion. To delineate hDFSC-specific effects, gingival epithelial cells (Ca9-22) were used as controls. Direct effects of hDFSCs on neutrophils (PMN) after interaction with bacteria were analyzed via chemotactic attraction, phagocytic activity and NET formation. We show that P. intermedia and T. forsythia adhere to and internalize into hDFSCs. This infection decreased the migratory capacity of the hDFSCs by 50%, did not disturb hDFSC differentiation potential and provoked an increase in IL-6 and IL-8 secretion while leaving IL-10 levels unaltered. These environmental modulations correlated with reduced PMN chemotaxis, phagocytic activity and NET formation. Our results suggest that P. intermedia and T. forsythia infected hDFSCs maintain their stem cell functionality, reduce PMN-induced tissue and bone degradation via suppression of PMN-activity, and at the same time allow for the survival of the oral pathogens.

Structure of RagB, a major immunodominant outer-membrane surface receptor antigen of Porphyromonas gingivalis

Porphyromonas gingivalis is the main causative agent of periodontitis. It deregulates the inflammatory and innate host immune responses through virulence factors, which include the immunodominant outer-membrane surface receptor antigens A (PgRagA) and B (PgRagB), co-transcribed from the rag pathogenicity island. The former is predicted to be a Ton-dependent porin-type translocator but the targets of this translocation and the molecular function of PgRagB are unknown. Phenomenologically, PgRagB has been linked with epithelial cell invasion and virulence according to murine models. It also acts as a Toll-like receptor agonist and promotes multiple mediators of inflammation. Hence, PgRagB is a candidate for the development of a periodontitis vaccine, which would be facilitated by the knowledge of its atomic structure. Here, we crystallized and solved the structure of 54-kDa PgRagB, which revealed a single domain centered on a curved helical scaffold. It consists of four tetratrico peptide repeats (TPR1-4), each arranged as two helices connected by a linker, plus two extra downstream capping helices. The concave surface bears four large intertwined irregular inserts (A-D), which contribute to an overall compact moiety. Overall, PgRagB shows substantial structural similarity with Bacteroides thetaiotaomicron SusD and Tannerella forsythia NanU, which are, respectively, engaged in binding and uptake of malto-oligosaccharide/starch and sialic acid. This suggests a similar sugar-binding function for PgRagB for uptake by the cognate PgRagA translocator, and, consistently, three potential monosaccharide-binding sites were tentatively assigned on the molecular surface.

Prevalence of periodontal pathogens as predictor of the evolution of periodontal status

The aim of this study was to determine the relationship between the prevalence of Porphyromonas gingivalis, its fimA genotypes, Aggregatibacter actinomycetemcomitans, Tannerella forsythia, and Treponema denticola and the evolution of periodontal health. In a longitudinal prospective study, samples of subgingival plaque were taken from 114 patients (37 with chronic periodontitis, 17 with gingivitis, and 60 periodontally healthy) in the course of a full periodontal examination. PCR was employed to determine the presence of the periodontopathogenic bacteria. Four years later, a second examination and sample collection were performed in 90 of these patients (20 with chronic periodontitis, 12 with gingivitis, and 58 periodontally healthy). T. forsythia, P. gingivalis, and T. denticola are the most prevalent bacteria in patients with chronic periodontitis (78.4%, 62.2 y 56.8%, respectively). The P. gingivalis bacterium and its fimA genotypes I, II, and IV showed the highest correlation between the baseline and follow-up assessments. P. gingivalis fimA genotype II and T. forsythia were associated to a significant degree with unfavourable periodontal evolution. Of the variables studied, P. gingivalis fimA genotype II and T. forsythia increase the risk of an unfavourable evolution of periodontal status.

Quantitative Molecular Detection of 19 Major Pathogens in the Interdental Biofilm of Periodontally Healthy Young Adults

In oral health, the interdental spaces are a real ecological niche for which the body has few or no alternative defenses and where the traditional daily methods for control by disrupting biofilm are not adequate. The interdental spaces are the source of many hypotheses regarding their potential associations with and/or causes of cardiovascular disease, diabetes, chronic kidney disease, degenerative disease, and depression. This PCR study is the first to describe the interdental microbiota in healthy adults aged 18–35 years-old with reference to the Socransky complexes. The complexes tended to reflect microbial succession events in developing dental biofilms. Early colonizers included members of the yellow, green, and purple complexes. The orange complex bacteria generally appear after the early colonizers and include many putative periodontal pathogens, such as Fusobacterium nucleatum. The red complex (Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola) was considered the climax community and is on the list of putative periodontal pathogens. The 19 major periodontal pathogens tested were expressed at various levels. F. nucleatum was the most abundant species, and the least abundant were Actinomyces viscosus, P. gingivalis, and Aggregatibacter actinomycetemcomitans. The genome counts for Eikenella corrodens, Campylobacter concisus, Campylobacter rectus, T. denticola, and Tannerella forsythensis increased significantly with subject age. The study highlights the observation that bacteria from the yellow complex (Streptococcus spp., S. mitis), the green complex (E. corrodens, Campylobacter gracilis, Capnocytophaga ochracea, Capnocytophaga sputigena, A. actinomycetemcomitans), the purple complex (Veillonella parvula, Actinomyces odontolyticus) and the blue complex (A. viscosus) are correlated. Concerning the orange complex, F. nucleatum is the most abundant species in interdental biofilm. The red complex, which is recognized as the most important pathogen in adult periodontal disease, represents 8.08% of the 19 bacteria analyzed. P. gingivalis was detected in 19% of healthy subjects and represents 0.02% of the interdental biofilm. T. forsythensis and T. denticola (0.02 and 0.04% of the interdental biofilm) were detected in 93 and 49% of healthy subjects, respectively. The effective presence of periodontal pathogens is a strong indicator of the need to develop new methods for disrupting interdental biofilm in daily oral hygiene.

Green tea catechins potentiate the effect of antibiotics and modulate adherence and gene expression in Porphyromonas gingivalis

OBJECTIVES

A number of studies have brought evidence that green tea catechins may contribute to periodontal health. The objective of this study was to investigate the ability of a green tea extract and its principal constituent epigallocatechin-3-gallate (EGCG) to potentiate the antibacterial effects of antibiotics (metronidazole, tetracycline) against Porphyromonas gingivalis, and to modulate the adherence to oral epithelial cells and expression of genes coding for virulence factors and the high temperature requirement A (HtrA) stress protein in P. gingivalis.

METHODS

A broth microdilution assay was used to determine the antibacterial activity of the green tea extract and EGCG. The synergistic effects of either compounds in association with metronidazole or tetracycline were evaluated using the checkerboard technique. A fluorescent assay was used to determine bacterial adherence to oral epithelial cells. The modulation of gene expression in P. gingivalis was evaluated by quantitative RT-PCR. The Vibrio harveyi bioassay was used for monitoring quorum sensing inhibitory activity.

RESULTS

The MIC values of the green tea extract on P. gingivalis ranged from 250 to 1000 μg/ml, while those of EGCG ranged from 125 to 500 μg/ml. A marked synergistic effect on P. gingivalis growth was observed for the green tea extract or EGCG in combination with metronidazole. Both the green tea extract and EGCG caused a dose-dependent inhibition of P. gingivalis adherence to oral epithelial cells. On the one hand, green tea extract and EGCG dose-dependently inhibited the expression of several P. gingivalis genes involved in host colonization (fimA, hagA, hagB), tissue destruction (rgpA, kgp), and heme acquisition (hem). On the other hand, both compounds increased the expression of the stress protein htrA gene. The ability of the green tea extract and EGCG to inhibit quorum sensing may contribute to the modulation of gene expression.

CONCLUSIONS

This study explored the preventive and therapeutic potential of green tea catechins against periodontal disease. In addition to inhibit growth and adherence of P. gingivalis, a green tea extract and its main constituent EGCG was found to decrease the expression of genes coding for the major virulence factors.

CX3CR1hi Monocyte/Macrophages Support Bacterial Survival and Experimental Infection-Driven Bone Resorption

Porphyromonas gingivalis,an anaerobic bacterium strongly linked to infection-driven inflammatory bone erosion, thrives within a highly inflamed milieu and disseminates to distant sites, such as atherosclerotic plaque. We examined the role of monocyte/macrophages in determining the outcome of infection with P. gingivalis. Surprisingly, transient monocyte/macrophage depletion led to greatly improved clearance of P. gingivalis. The chemokine receptors CCR2 and CX3CR1 play a major role in monocyte recruitment and differentiation to Ly6C(hi) vs CX3CR1(hi) subsets, respectively. To determine the contribution of particular monocyte/macrophage subsets to bacterial survival, we challenged chemokine receptor knockout mice and found that P. gingivalis clearance is significantly improved in the absence of CX3CR1. CX3CR1(hi) monocyte/macrophages promote P. gingivalis survival by downregulating neutrophil phagocytosis. Furthermore, CX3CR1 knockout mice resist bone resorption in the oral cavity following challenge with P. gingivalis Our findings provide an explanation for bacterial coexistence alongside an activate neutrophil infiltrate.

Gingipains from the Periodontal Pathogen Porphyromonas gingivalis Play a Significant Role in Regulation of Angiopoietin 1 and Angiopoietin 2 in Human Aortic Smooth Muscle Cells

Angiopoietin 1 (Angpt1) and angiopoietin 2 (Angpt2) are the ligands of tyrosine kinase (Tie) receptors, and they play important roles in vessel formation and the development of inflammatory diseases, such as atherosclerosis. Porphyromonas gingivalis is a Gram-negative periodontal bacterium that is thought to contribute to the progression of cardiovascular disease. The aim of this study was to investigate the role of P. gingivalis infection in the modulation of Angpt1 and Angpt2 in human aortic smooth muscle cells (AoSMCs). We exposed AoSMCs to wild-type (W50 and 381), gingipain mutant (E8 and K1A), and fimbrial mutant (DPG-3 and KRX-178) P. gingivalis strains and to different concentrations of tumor necrosis factor (TNF). The atherosclerosis risk factor TNF was used as a positive control in this study. We found that P. gingivalis (wild type, K1A, DPG3, and KRX178) and TNF upregulated the expression of Angpt2 and its transcription factor ETS1, respectively, in AoSMCs. In contrast, Angpt1 was inhibited by P. gingivalis and TNF. However, the RgpAB mutant E8 had no effect on the expression of Angpt1, Angpt2, or ETS1 in AoSMCs. The results also showed that ETS1 is critical for P. gingivalis induction of Angpt2. Exposure to Angpt2 protein enhanced the migration of AoSMCs but had no effect on proliferation. This study demonstrates that gingipains are crucial to the ability of P. gingivalis to markedly increase the expressed Angpt2/Angpt1 ratio in AoSMCs, which determines the regulatory role of angiopoietins in angiogenesis and their involvement in the development of atherosclerosis. These findings further support the association between periodontitis and cardiovascular disease.

The effect of metronidazole on the presence of P. gingivalis and T. forsythia at 3 and 12 months after different periodontal treatment strategies evaluated in a randomized, clinical trial

OBJECTIVE

The benefit of full-mouth disinfection (FDIS) over traditional scaling and root planing (SRP) in the treatment of chronic, destructive periodontitis remains equivocal and it is not known whether the use of adjunctive antibiotics may enhance the effect of FDIS. Therefore, the aim of this study was to evaluate the effect of conventional SRP completed over 21 days or 1-day FDIS, with or without systemically delivered adjunctive metronidazole (MET) on the presence of P. gingivalis and T. forsythia after 3 and 12 months.

MATERIALS AND METHODS

One hundred and eighty-four patients with moderate-to-severe periodontitis were randomly allocated to one of four treatment groups; (1) FDIS+MET; (2) FDIS+placebo; (3) SRP+MET; (4) SRP+placebo. Prior to treatment, pooled subgingival samples were obtained from the five deepest pockets. The same sites were sampled again 3 and 12 months after treatment. All samples were analyzed for P. gingivalis and T. forsythia by PCR, whereas A. actinomycetemcomitans and other bacteria were identified by culture techniques.

RESULTS

At baseline, 47% of the samples were positive for P. gingivalis, while almost all samples were positive for T. forsythia. The occurrence of P. gingivalis and T. forsythia was significantly reduced at 3 and 12 months after treatment in the FDIS+MET group, but not in the other treatment groups.

CONCLUSION

FDIS+MET had a significant effect in patients with P. gingivalis and T. forsythia, resulting in a significant reduction in number of patients where these micro-organisms could be detected at 3 and 12 months post-therapy.

Point-of-care detection of Tannerella forsythia using an antigen-antibody assisted dielectrophoretic impedance measurement method

The importance of periodontal treatment planning based on diagnosis with clinical detection of periodontal pathogens has been well recognized. However, reliable detection and quantification methods that can be conveniently used at chair-side have yet to be developed. This study aimed to evaluate the clinical use of a novel apparatus which uses an antigen-antibody reaction assisted dielectrophoretic impedance measurement (AA-DEPIM) for the detection of a prominent periodontal pathogen, Tannerella forsythia. A total of 15 patients with a clinical diagnosis of chronic periodontitis, three periodontally healthy volunteers and two with gingivitis were subjected to clinical and microbiological examinations. Saliva samples were analyzed for the presence of T. forsythia using AA-DEPIM, PCR-Invader and real-time PCR methods. The measurement values for total bacteria and T. forsythia using the prototype AA-DEPIM apparatus were significantly greater in periodontitis group than those in healthy/gingivitis group. Using the AA-DEPIM apparatus with tentative cut-off values, T. forsythia was detected for 14 (12 with periodontitis and 2 either healthy or with gingivitis) out of 20 individuals. The measurement for the detection of T. forsythia by the AA-DEPIM method showed a significant positive correlation with the detection by PCR-Invader (r = 0.541, p = 0.01) and the real-time PCR method (r = 0.834, p = 0.01). When the PCR-Invader method was used as a reference, the sensitivity and specificity of the AA-DEPIM method were 76.5% and 100%, respectively. The results suggested that the AA-DEPIM method has potential to be used for clinically evaluating salivary presence of T. forsythia at chair-side.

TRIAL REGISTRATION

UMIN Clinical Trials Registry (UMIN-CTR) UMIN000012181.

Infection with Porphyromonas gingivalis exacerbates endothelial injury in obese mice

BACKGROUND

A number of studies have revealed a link between chronic periodontitis and cardiovascular disease in obese patients. However, there is little information about the influence of periodontitis-associated bacteria, Porphyromonas gingivalis (Pg), on pathogenesis of atherosclerosis in obesity.

METHODS

In vivo experiment: C57BL/6J mice were fed with a high-fat diet (HFD) or normal chow diet (CD), as a control. Pg was infected from the pulp chamber. At 6 weeks post-infection, histological and immunohistochemical analysis of aortal tissues was performed. In vitro experiment: hTERT-immortalized human umbilical vein endothelial cells (HuhT1) were used to assess the effect of Pg/Pg-LPS on free fatty acid (FFA) induced endothelial cells apoptosis and regulation of cytokine gene expression.

RESULTS

Weaker staining of CD31 and increased numbers of TUNEL positive cells in aortal tissue of HFD mice indicated endothelial injury. Pg infection exacerbated the endothelial injury. Immunohistochemically, Pg was detected deep in the smooth muscle of the aorta, and the number of Pg cells in the aortal wall was higher in HFD mice than in CD mice. Moreover, in vitro, FFA treatment induced apoptosis in HuhT1 cells and exposure to Pg-LPS increased this effect. In addition, Pg and Pg-LPS both attenuated cytokine production in HuhT1 cells stimulated by palmitate.

CONCLUSIONS

Dental infection of Pg may contribute to pathogenesis of atherosclerosis by accelerating FFA-induced endothelial injury.

Effects of nonsurgical periodontal therapy on clinical response, microbiological profile, and glycemic control in Malaysian subjects with type 1 diabetes

The association between diabetes mellitus and chronic periodontal disease has long been established. Most of the researches linking these two very common chronic diseases were based on type 2 diabetes mellitus and chronic periodontal disease. However, this study was conducted to investigate the association between type 1 diabetes and chronic periodontal disease in Malaysian subjects. Forty-one Malaysian subjects, of which 20 subjects were type 1 diabetics and with chronic periodontal disease (test group) and 21 subjects with only chronic periodontal disease (control group), were included in the study. Periodontal parameters and plaque samples for microbiological evaluation were done at baseline, 2 and 3 months after nonsurgical periodontal therapy. Blood samples were taken from only the test group and evaluated for HbA1c at baseline and 3 months after periodontal therapy. There were no statistically significant difference in periodontal parameters between groups (P>0.05) and no significant improvement in the level of HbA1c in the test group. Microbiological studies indicated that there were significant reductions in the levels of the tested pathogens in both groups. The results of our study were similar to the findings of several other studies that had been done previously.

Influence of periodontitis on abdominal aortic aneurysms

Periodontitis is known to be a risk factor for abdominal aortic aneurysm (AAA). However, the influence of periodontitis on AAA development is to be elucidated. This article is to review the relationship between periodontitis and AAA. We focused on the roles of specific periodontopathic bacteria in AAA, matrix metalloproteinases and toll-like receptors in the pathophysiology in the section of experimental analysis. Furthermore, we showed clinical data of periodontitis in patients with AAA. We concluded that periodontal pathogens play a critical role in the AAA development.

Gingipains from Porphyromonas gingivalis play a significant role in induction and regulation of CXCL8 in THP-1 cells

Background

Porphyromonas gingivalis is an important bacterial etiological agent involved in periodontitis. The bacterium expresses two kinds of cysteine proteases called gingipains: arginine gingipains (RgpA/B) and lysine gingipain (Kgp). This study evaluated the interaction between P. gingivalis and THP-1 cells, a widely used monocytic cell line, in vitro with a focus on CXCL8 at the gene and protein levels and its fate thereafter in cell culture supernatants. THP-1 cells were stimulated with viable and heat-killed wild-type strains ATCC 33277 or W50 or viable isogenic gingipain mutants of W50, E8 (Rgp mutant) or K1A (Kgp mutant), for 24 hours.

Results

ELISA and qPCR results show an elevated CXCL8 expression and secretion in THP-1 cells in response to P. gingivalis, where the heat-killed ATCC33277 and W50 induced higher levels of CXCL8 in comparison to their viable counterparts. Furthermore, the Kgp-deficient mutant K1A caused a higher CXCL8 response compared to the Rgp-deficient E8. Chromogenic quantification of lipopolysaccharide (LPS) in supernatant showed no significant differences between viable and heat killed bacteria except that W50 shed highest levels of LPS. The wild-type strains secreted relatively more Rgp during the co-culture with THP-1 cells. The CXCL8 degradation assay of filter-sterilized supernatant from heat-killed W50 treated cells showed that Rgp was most efficient at CXCL8 hydrolysis. Of all tested P. gingivalis strains, adhesion and internalization in THP-1 cells was least conspicuous by Rgp-deficient P. gingivalis (E8), as demonstrated by confocal imaging.

Conclusions

W50 and its Kgp mutant K1A exhibit a higher immunogenic and proteolytic function in comparison to the Rgp mutant E8. Since K1A differs from E8 in the expression of Rgp, it is rational to conclude that Rgp contributes to immunomodulation in a more dynamic manner in comparison to Kgp. Also, W50 is a more virulent strain when compared to the laboratory strain ATCC33277.

Analysis of a Lys-specific serine endopeptidase secreted via the type IX secretion system in Porphyromonas gingivalis

Porphyromonas gingivalis, a significant causative agent of adult periodontitis, possesses a novel secretion system called the type IX secretion system (T9SS). A number of virulence factors, such as Arg-gingipain (Rgp), are translocated onto the cell surface and into the extracellular milieu via the T9SS. In this study, we found that the PGN_1416 90- to 120-kDa diffuse protein bands were located in the outer membrane fraction and that the presence of the bands was dependent on genes involved in the T9SS and the formation of anionic lipopolysaccharide (A-LPS). These data strongly suggest that the PGN_1416 protein is secreted by the T9SS and anchored onto the cell surface by binding to A-LPS. Enzymatic analysis using outer membrane fractions suggested that the PGN_1416 protein has a Lys-specific serine endopeptidase activity and that its activation requires processing by Rgp. Homologues of the gene encoding PGN_1416, which is referred to as pepK, were found in bacteria belonging to the phyla Bacteroidetes and Proteobacteria, whereas homologues encoding the C-terminal domain, which is essential for T9SS-mediated secretion, and the catalytic domain were only observed in bacteria belonging to the Bacteroidetes phylum.