Periodontopathic bacteria and herpesviruses in chronic periodontitis

Viruses of the oral cavity: Prevalence, pathobiology and association with oral diseases

The human oral cavity contains a plethora of habitats and tissue environments, such as teeth, tongue, and gingiva, which are home to a rich microbial flora including bacteria, fungi, and viruses. Given the exposed nature of the mouth, oral tissues constantly encounter infectious agents, forming a complex ecological community. In the past, the discussion of microbiological aspects of oral disease has traditionally focused on bacteria and fungi, but viruses are attracting increasing attention as pathogens in oral inflammatory diseases. Therefore, understanding viral prevalence, pathogenicity, and preference regarding oral tissues is critical to understanding the holistic effects of viruses on oral infections. Recent investigations have demonstrated the abundance of certain viruses in oral inflammatory diseases, suggesting an association between viruses and disease. Human herpesviruses are the most extensively studied viruses in different oral inflammatory diseases. However, challenges in viral detection and the lack of reproducible in vitro and in vivo infection models have limited our progress in understanding viruses and their contribution to oral diseases. This review presents a summary of major mammalian viruses and associated diseases in the human oral cavity. The emergence of a recent pathogen SARS-CoV-2 and its tropism for salivary and periodontal tissues further highlights the relevance of the oral cavity in host-pathogen interaction. Understanding how these different viruses present clinically and influence oral health will advance our understanding of multifactorial oral diseases and their association with viruses.

Masulili SL, Soeroso Y, Djoko Santoso W, S. Kusdhany L. Association between Epstein-Barr virus and periodontitis: A meta-analysis

Purpose

Previous studies have found that Epstein-Barr virus (EBV) is associated with periodontitis, though some controversy remains. This meta-analysis aimed to clarify and update the relationship between EBV and periodontitis as well as clinical parameters.

Methods

A comprehensive search was conducted in the PubMed and Scopus databases in December 2020. Original data were extracted according to defined inclusion and exclusion criteria. Outcomes were analyzed, including overall odds ratios (ORs) and 95% confidence intervals (CIs). A random-effects model was used, and publication bias was assessed by Egger’s and Begg’s tests. Sensitivity analysis was used to evaluate the stability of the outcome.

Results

Twenty-six studies were included in the present meta-analysis, involving 1354 periodontitis patients and 819 healthy controls. The included studies mostly showed high quality. The overall quantitative synthesis for the association between EBV and periodontitis was an increased odds ratio when subgingival EBV was detected OR = 7.069, 95% CI = 4.197–11.905, P<0.001). The results of subgroup analysis suggested that the association of EBV with periodontitis was significant in Asian, European, and American populations (P<0.001; P = 0.04; P = 0.003, respectively) but not in African populations (P = 0.29). Subgroup analysis by sample type showed that subgingival plaque (SgP), tissue and gingival crevicular fluid GCF were useful for EBV detection (P<0.001). EBV detection amplification methods included nested PCR, multiplex PCR and PCR (P<0.001; P = 0.05, P<0.001, respectively), but EBV detection by real-time PCR and loop-mediated isothermal amplification presented no significant result (P = 0.06; P = 0.3, respectively). For the clinical parameters of periodontitis, pocket depth (PD) and bleeding of probing (BOP) percentages were higher in the EBV-positive sites than in the EBV-negative sites (MD 0.47 [0.08, 0.85], P = 0.02; MD 19.45 [4.47, 34.43], P = 0.01).

Conclusions

A high frequency of EBV detection is associated with an increased risk of periodontitis. The EBV association was particularly significant in all populations except in African populations. Subgigival plaque (SgP), tissue and GCF were not significantly different useful material for detecting EBV in periodontitis. Nested PCR and multiplex PCR are reliable methods for this purpose. In the presence of EBV, PD and BOP are reliable clinical parameters for gingival inflammation. However, some caution in such interpretation is justified due to heterogeneity among studies. A suggested extension could assess the parallel influence of other human herpesviruses.

Association of subgingival Epstein-Barr virus and periodontitis

Background: The Epstein–Barr virus (EBV) is gaining interest as a possible agent in the etiology of periodontitis. Previous studies have shown controversy on whether EBV DNA in the subgingival periodontal pockets is associated with periodontitis. The present study aimed to seek the potential relationship between EBV and periodontitis.

Methods: Samples were taken from gingival crevicular fluid using sterile paper points, and data on sociodemographics, oral health, and periodontal health were recorded. This case-control study of 118 participants included 59 subjects with severe periodontitis and 59 control subjects with mild periodontitis. Quantitative real-time PCR was used to determined EBV load.

Results: EBV DNA was detected in 37.3% of the case samples and 18.6% of the control samples. There was no significant difference in a load of EBV DNA between severe and mild periodontitis (p>0.05). The observed load of EBV DNA was up to 4.55x10 ⁵ copies/mL. The detected EBV DNA was significantly associated with the plaque index and the oral hygiene index (p<0.05).

Conclusions: Although no significant association was found, EBV may play a role in periodontitis. The real-time PCR methods can be used to monitor the EBV load in gingival crevicular fluid.

The oralome and its dysbiosis: New insights into oral microbiome-host interactions

The oralome is the summary of the dynamic interactions orchestrated between the ecological community of oral microorganisms (comprised of up to approximately 1000 species of bacteria, fungi, viruses, archaea and protozoa - the oral microbiome) that live in the oral cavity and the host. These microorganisms form a complex ecosystem that thrive in the dynamic oral environment in a symbiotic relationship with the human host. However, the microbial composition is significantly affected by interspecies and host-microbial interactions, which in turn, can impact the health and disease status of the host. In this review, we discuss the composition of the oralome and inter-species and host-microbial interactions that take place in the oral cavity and examine how these interactions change from healthy (eubiotic) to disease (dysbiotic) states. We further discuss the dysbiotic signatures associated with periodontitis and caries and their sequalae, (e.g., tooth/bone loss and pulpitis), and the systemic diseases associated with these oral diseases, such as infective endocarditis, atherosclerosis, diabetes, Alzheimer's disease and head and neck/oral cancer. We then discuss current computational techniques to assess dysbiotic oral microbiome changes. Lastly, we discuss current and novel techniques for modulation of the dysbiotic oral microbiome that may help in disease prevention and treatment, including standard hygiene methods, prebiotics, probiotics, use of nano-sized drug delivery systems (nano-DDS), extracellular polymeric matrix (EPM) disruption, and host response modulators.

Detection of Epstein-Barr Virus in Periodontitis: A Review of Methodological Approaches

Periodontitis, an inflammatory condition that affects the structures surrounding the tooth eventually leading to tooth loss, is one of the two biggest threats to oral health. Beyond oral health, it is associated with systemic diseases and even with cancer risk. Obviously, periodontitis represents a major global health problem with significant social and economic impact. Recently, a new paradigm was proposed in the etiopathogenesis of periodontitis involving a herpesviral–bacterial combination to promote long-term chronic inflammatory disease. Periodontitis as a risk factor for other systemic diseases can also be better explained based on viral–bacterial etiology. Significant efforts have brought numerous advances in revealing the links between periodontitis and Epstein–Barr virus (EBV), a gamma herpesvirus ubiquitous in the adult human population. The strong evidence from these studies may contribute to the advancement of periodontitis research and the ultimate control of the disease. Advancing the periodontitis research will require implementing suitable methods to establish EBV involvement in periodontitis. This review evaluates and summarizes the existing methods that allow the detection and diagnosis of EBV in periodontitis (also applicable in a more general way to other EBV-related diseases), and discusses the feasibility of the application of innovative emerging technologies.

Butyric Acid in Saliva of Chronic Periodontitis Patients Induces Transcription of the EBV Lytic Switch Activator BZLF1: A Pilot Study

BACKGROUND/AIM

Epstein-Barr virus (EBV) associates with human chronic periodontitis (CP) progression. We previously demonstrated that butyric acid (BA), produced by periodontopathic bacteria, induced EBV lytic switch activator BZLF1 expression. We investigated whether short chain fatty acids (SCFAs) in CP patients' saliva enabled EBV reactivation.

MATERIALS AND METHODS

Saliva was collected from seven CP patients and five periodontally healthy individuals. SCFAs were quantified using HPLC. BZLF1 mRNA and its pertinent protein ZEBRA were determined with Real-time PCR and western blotting. Histone H3 acetylation (AcH3) was further examined.

RESULTS

BZLF1 mRNA expression and transcriptional activity in EBV-infected Daudi cells were induced only when treated with the CP saliva. Among SCFAs, BA alone correlated significantly with the BZLF1 transcription (r=0.88; p<0.02). As expected, CP patients' saliva induced AcH3.

CONCLUSION

BA in saliva may play a role in EBV reactivation and hence contribute to EBV-related disease progression in CP patients.

Relationship between herpesviruses and periodontal disease progression

AIM

To investigate the role of Epstein-Barr virus (EBV), cytomegalovirus (CMV), and anaerobic bacteria in the progression of periodontitis.

METHODS

Eighty-one adults with generalized moderate to severe periodontitis were randomly assigned to: oral hygiene or scaling and root planning ± placebo or polyunsaturated fatty acids fish oil. Subgingival plaque samples collected from three healthy and three disease sites at weeks 0, 16, and 28 and from sites demonstrating disease progression were analysed for EBV, CMV, P. gingivalis (Pg), T. forsythia (Tf), and T. denticola (Td) DNA using quantitative polymerase chain reaction.

RESULTS

Cytomegalovirus was detected in 0.3% (4/1454) sites. EBV was present in 12.2% of healthy sites (89/728) and 27.6% disease sites (201/726; p < .0001), but was in low copy number. Disease progression occurred in 28.4% of participants (23/81) and developed predominantly at sites identified as diseased (75/78; 96.2%). CMV and EBV were not associated with disease progression (p = .13) regardless of treatment. In contrast, disease sites were associated with higher levels of Pg, Td, Tf, and total bacteria, and sites that exhibited disease progression were associated with an abundance of Td and Tf (p < .04).

CONCLUSION

Disease progression was associated with Gram-negative anaerobic bacteria; not EBV or CMV.

How Does Epstein-Barr Virus Contribute to Chronic Periodontitis?

Chronic periodontitis is spreading worldwide and mutually interacts with systemic diseases like diabetes mellitus. Although periodontopathic bacteria are inevitable pathogens in their onset and progression, many cases are not ascribable to the virulence of these bacteria because the effect of plaque control is limited. In contrast, Epstein-Barr virus (EBV) in the periodontium has been correlated with chronic periodontitis and has recently been considered as a promising pathogenic candidate for this disease. However, several important questions have yet to be addressed. For instance, although EBV latently infects more than 90% of individuals over the world, why do patients with chronic periodontitis exclusively harbor progeny EBV in the oral cavity? In addition, how does latently infected or reactivated EBV in the periodontium relate to the onset or progression of chronic periodontitis? Finally, is periodontitis incurable because EBV is the pathogen for chronic periodontitis? In this review, we attempt to answer these questions by reporting the current understanding of molecular relations and mechanisms between periodontopathic bacteria and EBV reactivation in the context of how this relationship may pertain to the etiology of chronic periodontitis.

Herpesvirus-bacteria synergistic interaction in periodontitis

The etiopathogenesis of severe periodontitis includes herpesvirus-bacteria coinfection. This article evaluates the pathogenicity of herpesviruses (cytomegalovirus and Epstein-Barr virus) and periodontopathic bacteria (Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis) and coinfection of these infectious agents in the initiation and progression of periodontitis. Cytomegalovirus and A. actinomycetemcomitans/P. gingivalis exercise synergistic pathogenicity in the development of localized ("aggressive") juvenile periodontitis. Cytomegalovirus and Epstein-Barr virus are associated with P. gingivalis in adult types of periodontitis. Periodontal herpesviruses that enter the general circulation may also contribute to disease development in various organ systems. A 2-way interaction is likely to occur between periodontal herpesviruses and periodontopathic bacteria, with herpesviruses promoting bacterial upgrowth, and bacterial factors reactivating latent herpesviruses. Bacterial-induced gingivitis may facilitate herpesvirus colonization of the periodontium, and herpesvirus infections may impede the antibacterial host defense and alter periodontal cells to predispose for bacterial adherence and invasion. Herpesvirus-bacteria synergistic interactions, are likely to comprise an important pathogenic determinant of aggressive periodontitis. However, mechanistic investigations into the molecular and cellular interaction between periodontal herpesviruses and bacteria are still scarce. Herpesvirus-bacteria coinfection studies may yield significant new discoveries of pathogenic determinants, and drug and vaccine targets to minimize or prevent periodontitis and periodontitis-related systemic diseases.

Prevalence of two Entamoeba gingivalis ST1 and ST2-kamaktli subtypes in the human oral cavity under various conditions

Advances in molecular biology have facilitated analyses of the oral microbiome; however, the parasites role is poorly understood. Periodontal disease is a multifactorial process involving complex interactions among microorganisms, the host, and environmental factors. At present, the precise composition of the mouth parasites microbiota is unclear. Two protozoan species have been detected in the oral microbiota: Trichomonas tenax and Entamoeba gingivalis, and a new variant, E. gingivalis-ST2-kamaktli, was recently identified by us. In this study, both E. gingivalis and the new E. gingivalis-ST2-kamaktli variant were detected in the oral cavities of people with healthy periodontium, individuals undergoing orthodontic treatment, and patients with periodontal disease. In the group with healthy periodontium, the prevalence of E. gingivalis-ST1 was 48.6% and that of E. gingivalis-ST2-kamaktli 29.5%, with a combined prevalence of 54.3%. In patients undergoing orthodontics treatment, 81.2% carried both amoebas, with 47.5% having E. gingivalis-ST1 and 73.8% E. gingivalis-ST2-kamaktli. In people with periodontal disease, the prevalence of E. gingivalis-ST1 was 57.8%, and that of E. gingivalis-ST2-kamaktli 50.0%, with a combined prevalence of 73.5%; hence, E. gingivalis-ST1 and E gingivalis-ST2-kamaktli were detected in all three groups. The question arises, what are E. gingivalis-ST1 and E. gingivalis-ST2-kamaktli doing in the oral cavity? Although, the answer remains unclear, our results suggest that each amoeba subtype is genetically distinct, and they exhibit different patterns of infectious behavior. We hypothesize that E. gingivalis-ST1 and E. gingivalis-ST2-kamaktli may represent separate species. Our data contribute to better understanding of the roles of E. gingivalis-ST1 and E. gingivalis-ST2-kamaktli in the oral microbiota.

Prevalence of Epstein-Barr virus DNA and Porphyromonas gingivalis in Japanese peri-implantitis patients

Background

Peri-implantitis (PI) is an inflammatory reaction associated with functional deterioration of supporting bones around the dental implant. Recent studies suggested Epstein–Barr virus (EBV) is involved in the pathogenesis of periodontitis. We investigated the association between EBV and Porphyromonas gingivalis in Japanese PI patients.

Methods

Fifteen periodontally healthy individuals, 15 healthy implant patients and 15 PI patients were recruited. Forty five subgingival plaque samples were collected from the deepest probing pocket depth (PPD) site from each patient. Real-time PCR was used to detect EBV DNA and P. gingivalis.

Results

EBV and P. gingivalis were detected in 7 and 3 PPD sites of the healthy controls, in 9 and 4 PPD sites of the healthy implants, and in 13 and 14 PPD sites of the PI patients. P. gingivalis and coexistence of EBV and P. gingivalis were detected significantly higher in the PI patients than healthy controls and healthy implant patients. EBV was detected significantly higher in the PI patients than healthy controls.

Conclusions

Higher levels of EBV and P. gingivalis were detected in PPD sites of PI patients. These results suggest that coexistence of EBV and P. gingivalis may serve pathogenic factors cause for PI in Japanese dental patients.

Association of interferon lambda-1 with herpes simplex viruses-1 and -2, Epstein-Barr virus, and human cytomegalovirus in chronic periodontitis

AIM

Periodontal tissues facilitate the homing of herpes viruses that elicit the immune-inflammatory response releasing the interferons (IFN). IFN lambda-1 (λ1) can suppress the replication of viruses, and induces the antiviral mechanism. The aim of the present study was to evaluate the association between IFN-λ1 and periodontal herpes viruses in the immunoregulation of chronic periodontal disease.

METHODS

The cross-sectional study design included 30 chronic periodontitis patients with a mean age of 42.30 ± 8.63 years. Gingival crevicular fluid collected was assessed for IFN-λ1 using enzyme-linked immunosorbent assay and four herpes viruses were detected using multiplex polymerase chain reaction technique. IFN-λ1 levels were compared between virus-positive and -negative patients for individual and total viruses.

RESULTS

Fifty per cent (n = 15) of patients were positive for the four herpes viruses together; 50% (n = 15), 30% (n = 9), 26.7% (n = 8), and 40% (n = 12) were positive for herpes simplex virus (HSV)-1, Epstein-Barr virus, HSV-2, and human cytomegalovirus, respectively. The mean concentrations of IFN-λ1 in virus-positive patients (14.38 ± 13.95) were lower than those of virus-negative patients (228.26 ± 215.35). INF-λ1 levels in individual virus groups were also lower in virus-positive patients compared to virus-negative patients, with P < 0.001.

CONCLUSIONS

These results suggest that IFN-λ1 could have antiviral and therapeutic value against the viruses in the pathogenesis of chronic periodontitis.

Epstein-Barr virus is associated with periodontal diseases: A meta-analysis based on 21 case-control studies

Some controversies still exist between the detection of Epstein-Barr virus (EBV)'s DNA and risks of periodontal diseases. Hence, a comprehensive meta-analysis on all available literatures was performed to clarify the relationship between EBV and preidontitis.A comprehensive search was conducted within the PUBMED, EMBASE, and WANFANG databases up to October 10th, 2016 according to inclusion and exclusion criteria and finally 21 case-control literatures were obtained. The outcomes including odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of associations. Publication bias was determined by Begg or Egger test. Sensitivity analysis was used to investigate reliability and stability of the results.According to the data from included trials, the association between overall increased risks of periodontitis and the detection of EBV was significant (OR = 6.199, 95% CI = 3.119-12.319, P < 0.001). In the disease-type analysis, the pooled ORs for chronic periodontitis and aggressive periodontitis were 6.586 (95% CI = 3.042-14.262, P < 0.001) and 8.361 (95% CI = 2.109-33.143, P = 0.003), respectively. In the subgroup analysis of ethnicity, our results suggested that high EBV-detecting frequencies were correlated with increased risks of periodontitis in Asians, Europeans, and Americans (P < 0.001). Subgroup analysis by the sample type showed that subgingival plaque (SgP) samples and tissue samples were available for EBV detecting (P < 0.001). Detecting EBV of samples in ≥5 (6) mm sites of periodontal pockets were easier than in ≤3-mm sites (P = 0.023).This meta-analysis indicates that high frequent detection of EBV correlates with increased risk of periodontal diseases. SgP and tissue are available for detecting EBV in patients of periodontitis. At last, our results suggest that detecting EBV of samples in =5 (6) mm sites of periodontal pockets are more sensitive than in ≤3-mm sites.

Herpesviruses dUTPases: A New Family of Pathogen-Associated Molecular Pattern (PAMP) Proteins with Implications for Human Disease

The human herpesviruses are ubiquitous viruses and have a prevalence of over 90% in the adult population. Following a primary infection they establish latency and can be reactivated over a person's lifetime. While it is well accepted that human herpesviruses are implicated in numerous diseases ranging from dermatological and autoimmune disease to cancer, the role of lytic proteins in the pathophysiology of herpesvirus-associated diseases remains largely understudies. Only recently have we begun to appreciate the importance of lytic proteins produced during reactivation of the virus, in particular the deoxyuridine triphosphate nucleotidohydrolases (dUTPase), as key modulators of the host innate and adaptive immune responses. In this review, we provide evidence from animal and human studies of the Epstein-Barr virus as a prototype, supporting the notion that herpesviruses dUTPases are a family of proteins with unique immunoregulatory functions that can alter the inflammatory microenvironment and thus exacerbate the immune pathology of herpesvirus-related diseases including myalgic encephalomyelitis/chronic fatigue syndrome, autoimmune diseases, and cancer.

Herpesviral-bacterial co-infection in mandibular third molar pericoronitis

OBJECTIVE

The aim of this study was to assess the presence of herpesviruses and periodontopathic bacteria and to establish their potential association with pericoronitis.

MATERIALS AND METHODS

Fifty samples obtained with paper points (30 from pericoronitis and 20 controls) were subjected to polymerase chain reaction (PCR) analysis. A single-stage and nested PCR assays were used to detect herpesviruses: human cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) and six periodontopathic anaerobic bacteria: Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Parvimonas micra, Treponema denticola, and Tannarella forsythia.

RESULTS

Pericoronitis samples harbored HCMV and EBV at significantly higher rates than the control group (70 vs. 40 % and 46.7 vs. 15 %, P = 0.035, P = 0.021, respectively). P. micra and T. forsythia (66.7 vs. 0 %, and 40 vs. 10 %, P = 0.001, P = 0.021, respectively) were significantly more common in pericoronitis compared to the control group. Multivariate logistic regression analysis showed that the presence of T. forsythia was associated with pericoronitis development (OR 7.3, 95 % CI, 1.2-43.2, P = 0.028).

CONCLUSION

The occurrence of HCVM and EBV extends our previous knowledge on microbiota in pericoronitis. These PCR-based findings demonstrated that bacterial and viral DNA occurred concomitantly in pericoronitis samples. T. forsythia appeared to be significantly associated with pericoronitis development in the examined sample.

CLINICAL RELEVANCE

Herpesviral-bacterial co-infections might exacerbate the progression of pericoronitis.

Association between Herpesviruses and Chronic Periodontitis: A Meta-Analysis Based on Case-Control Studies

OBJECTIVE

Numerous studies have investigated the associations between herpesviruses and chronic periodontitis; however, the results remain controversial. To derive a more precise estimation, a meta-analysis on all available studies was performed to identify the association between herpesviruses and chronic periodontitis.

METHODS

A computerized literature search was conducted in December 2014 to identify eligible case-control studies from the PUBMED and EMBASE databases according to inclusion and exclusion criteria. Data were extracted and pooled odds ratios (OR) with 95% confidence intervals (CI) were used to assess the association between herpesviruses and risk of chronic periodontitis. A fixed or random effects model was determined based on a heterogeneity test. Sensitivity analysis was conducted to investigate stability and reliability. Publication bias was investigated using the Begg rank correlation test and Egger's funnel plot.

RESULTS

Ten eligible studies were included to investigate the association between Epstein-Barr virus (EBV) and chronic periodontitis. The results showed that EBV has a significant association with chronic periodontitis compared with periodontally healthy group (OR = 5.74, 95% CI = 2.53-13.00, P<0.001). The association between human cytomegalovirus (HCMV) and chronic periodontitis was analyzed in 10 studies. The pooled result showed that HCMV also has a significant association with chronic periodontitis (OR = 3.59, 95% CI = 1.41-9.16, P = 0.007). Similar results were found in the sensitivity analyses. No significant publication bias was observed. Two eligible studies were included to investigate the association between herpes simplex virus (HSV) and chronic periodontitis risk. The association between HSV and chronic periodontitis was inconclusive (OR = 2.81 95% CI = 0.95-8.27, P = 0.06). Only one included study investigated the association between human herpesvirus 7 (HHV-7) and chronic periodontitis risk (OR = 1.00, 95% CI = 0.21-4.86).

CONCLUSION

The findings of this meta-analysis suggest that two members of the herpesvirus family, EBV and HCMV, are significantly associated with chronic periodontitis. There is insufficient evidence to support associations between HSV, HHV-7 and chronic periodontitis.

Porphyromonas gingivalis and Epstein-Barr Virus Are Associated With Increased Levels of Visfatin in Gingival Crevicular Fluid

BACKGROUND

There is little clinical information on the relationship between periodontopathogens and visfatin. The purpose of this study is to determine visfatin levels in the gingival crevicular fluid (GCF) of healthy individuals and patients with periodontitis and to investigate the possible relationship between this adipokine and the presence and levels of Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescense, and Epstein-Barr virus (EBV).

METHODS

Eighteen healthy individuals and 27 patients with periodontitis were included in this study. GCF and plaque samples were obtained from all individuals. Visfatin levels were analyzed by enzyme-linked immunosorbent assay, and the bacterial numbers were evaluated by the reverse transcription-polymerase chain reaction method.

RESULTS

In patients with periodontitis, the visfatin levels in the GCF (mean: 84.29 ng/mL; range: 63.8 to 108.9 ng/mL) were significantly higher compared with those of the healthy individuals (mean: 38.06 ng/mL; range: 13.8 to 89.02 ng/mL) (P <0.01). There was a positive correlation between the visfatin levels and P. gingivalis (r = 0.266, P <0.05), whereas no correlation was found between visfatin levels and other microorganisms. In addition, the visfatin levels were found to be higher in individuals in whom P. gingivalis was detected than for those without P. gingivalis (P <0.01). The visfatin levels were also found to be higher in individuals in whom EBV was detected (P <0.05).

CONCLUSIONS

To the best of the authors' knowledge, the present study is the first one to show the correlation of periodontopathogens and GCF visfatin levels. P. gingivalis colonization of the periodontal pockets may increase visfatin secretion. Furthermore, the presence of EBV in the plaque may be another factor that causes an increase in visfatin levels.

Transcriptome analysis of bacteriophage communities in periodontal health and disease

BACKGROUND

The role of viruses as members of the human microbiome has gained broader attention with the discovery that human body surfaces are inhabited by sizeable viral communities. The majority of the viruses identified in these communities have been bacteriophages that predate upon cellular microbiota rather than the human host. Phages have the capacity to lyse their hosts or provide them with selective advantages through lysogenic conversion, which could help determine the structure of co-existing bacterial communities. Because conditions such as periodontitis are associated with altered bacterial biota, phage mediated perturbations of bacterial communities have been hypothesized to play a role in promoting periodontal disease. Oral phage communities also differ significantly between periodontal health and disease, but the gene expression of oral phage communities has not been previously examined.

RESULTS

Here, we provide the first report of gene expression profiles from the oral bacteriophage community using RNA sequencing, and find that oral phages are more highly expressed in subjects with relative periodontal health. While lysins were highly expressed, the high proportion of integrases expressed suggests that prophages may account for a considerable proportion of oral phage gene expression. Many of the transcriptome reads matched phages found in the oral cavities of the subjects studied, indicating that phages may account for a substantial proportion of oral gene expression. Reads homologous to siphoviruses that infect Firmicutes were amongst the most prevalent transcriptome reads identified in both periodontal health and disease. Some genes from the phage lytic module were significantly more highly expressed in subjects with periodontal disease, suggesting that periodontitis may favor the expression of some lytic phages.

CONCLUSIONS

As we explore the contributions of viruses to the human microbiome, the data presented here suggest varying expression of bacteriophage communities in oral health and disease.

Epstein-Barr virus in the enlarged salivary tissues of patients with IgG4-related disease

OBJECTIVE

Immunoglobulin G4-related disease (IgG4-RD) is a recently recognized disease entity characterized by high-serum IgG4 concentration and IgG4-producing plasma cell production with fibrotic or sclerotic changes in affected organs. We aimed to clarify the roles of Epstein-Barr virus (EBV) in patients with IgG4-RDs.

STUDY DESIGN AND SETTING

A retrospective clinical study at the Yamagata University School of Medicine, Yamagata, Japan.

METHODS

The patient group consisted of four males and four females with an average age of 62 years (range: 48-73). Expression of IgG4, latent member protein 1, EBV nuclear antigens-2, and EBV-encoded RNA in affected salivary glands from patients with IgG4-RD was examined by using immunohistochemistry and in situ hybridization. The copy number of EBV DNA in the salivary glands was also investigated by real-time polymerase chain reaction.

RESULTS

All patients had hard masses in the salivary or lacrimal glands, or both, bilaterally. Serum concentrations of IgG4 were elevated in all cases (mean 589.1, range 129-1750), and IgG4-positive plasmacytes were observed in the involved salivary glands. Four patients developed potentially life-threatening systemic involvement after initial salivary gland swelling. EBV-associated molecules (EBNA and EBER) were overexpressed in the affected salivary glands. The copy number of EBV DNA was significantly higher in patients with potentially life-threatening systemic involvement than in patients without systemic involvement (P < 0.05).

CONCLUSION

These results suggest that the copy number of EBV DNA could be useful as diagnostic findings in IgG4-RD to predict potentially life-threatening systemic involvement.

LEVEL OF EVIDENCE

4.

Prevalence and quantitative analysis of Epstein-Barr virus DNA and Porphyromonas gingivalis associated with Japanese chronic periodontitis patients

Objective

A number of studies have recently suggested Epstein–Barr virus (EBV) involvement in the pathogenesis of periodontitis. In this study, we investigated the association between major periodontopathic bacteria Porphyromonas gingivalis (P. gingivalis) and EBV in Japanese chronic periodontitis (CP) patients.

Materials and methods

A group of 25 patients with CP participated in the study along with 13 individuals without periodontitis. Subgingival samples were obtained with paper points. Quantitative real-time polymerase chain reaction (PCR) was used to detect EBV DNA and P. gingivalis.

Results

In the CP patients, EBV DNA and P. gingivalis were detected in both 80 % of sites with probing pocket depths (PPD) of ≥5 mm and in 40 and 36 % of sites with PPD ≤3 mm, respectively. EBV DNA and P. gingivalis were detected in 50 and 27 % of the sites in periodontally healthy individuals. Coexistence of EBV DNA and P. gingivalis was significantly higher in the deeper PPD sites of CP patients (68 %) than in the PPD sites of the healthy controls (15 %) and shallow PPD sites of CP patients (12 %). PCR-positive deeper PPD sites of CP patients for EBV DNA and P. gingivalis range between 3.74 × 10³∼2.83 × 10⁹ and 2.73 × 10⁵∼6.65 × 10⁹ (copies/ml), respectively.

Conclusion

These results suggest an association between EBV DNA, P. gingivalis, and CP in Japanese individuals. Further studies are required to clarify this association; however, we believe that our enhanced understanding of the pathogenesis of periodontal diseases involving viral infections will lead to new treatments.

Characterizing the S-layer structure and anti-S-layer antibody recognition on intact Tannerella forsythia cells by scanning probe microscopy and small angle X-ray scattering

Tannerella forsythia is among the most potent triggers of periodontal diseases, and approaches to understand underlying mechanisms are currently intensively pursued. A ~22-nm-thick, 2D crystalline surface (S-) layer that completely covers Tannerella forsythia cells is crucially involved in the bacterium-host cross-talk. The S-layer is composed of two intercalating glycoproteins (TfsA-GP, TfsB-GP) that are aligned into a periodic lattice. To characterize this unique S-layer structure at the nanometer scale directly on intact T. forsythia cells, three complementary methods, i.e., small-angle X-ray scattering (SAXS), atomic force microscopy (AFM), and single-molecular force spectroscopy (SMFS), were applied. SAXS served as a difference method using signals from wild-type and S-layer-deficient cells for data evaluation, revealing two possible models for the assembly of the glycoproteins. Direct high-resolution imaging of the outer surface of T. forsythia wild-type cells by AFM revealed a p4 structure with a lattice constant of ~9.0 nm. In contrast, on mutant cells, no periodic lattice could be visualized. Additionally, SMFS was used to probe specific interaction forces between an anti-TfsA antibody coupled to the AFM tip and the S-layer as present on T. forsythia wild-type and mutant cells, displaying TfsA-GP alone. Unbinding forces between the antibody and wild-type cells were greater than with mutant cells. This indicated that the TfsA-GP is not so strongly attached to the mutant cell surface when the co-assembling TfsB-GP is missing. Altogether, the data gained from SAXS, AFM, and SMFS confirm the current model of the S-layer architecture with two intercalating S-layer glycoproteins and TfsA-GP being mainly outwardly oriented.

Altered oral viral ecology in association with periodontal disease

The human oral cavity is home to a large and diverse community of viruses that have yet to be characterized in patients with periodontal disease. We recruited and sampled saliva and oral biofilm from a cohort of humans either periodontally healthy or with mild or significant periodontal disease to discern whether there are differences in viral communities that reflect their oral health status. We found communities of viruses inhabiting saliva and the subgingival and supragingival biofilms of each subject that were composed largely of bacteriophage. While there were homologous viruses common to different subjects and biogeographic sites, for most of the subjects, virome compositions were significantly associated with the oral sites from which they were derived. The largest distinctions between virome compositions were found when comparing the subgingival and supragingival biofilms to those of planktonic saliva. Differences in virome composition were significantly associated with oral health status for both subgingival and supragingival biofilm viruses but not for salivary viruses. Among the differences identified in virome compositions was a significant expansion of myoviruses in subgingival biofilm, suggesting that periodontal disease favors lytic phage. We also characterized the bacterial communities in each subject at each biogeographic site by using the V3 hypervariable segment of the 16S rRNA and did not identify distinctions between oral health and disease similar to those found in viral communities. The significantly altered ecology of viruses of oral biofilm in subjects with periodontal disease compared to that of relatively periodontally healthy ones suggests that viruses may serve as useful indicators of oral health status.

Little is known about the role or the constituents of viruses as members of the human microbiome. We investigated the composition of human oral viral communities in a group of relatively periodontally healthy subjects or significant periodontitis to determine whether health status may be associated with differences in viruses. We found that most of the viruses present were predators of bacteria. The viruses inhabiting dental plaque were significantly different on the basis of oral health status, while those present in saliva were not. Dental plaque viruses in periodontitis were predicted to be significantly more likely to kill their bacterial hosts than those found in healthy mouths. Because oral diseases such as periodontitis have been shown to have altered bacterial communities, we believe that viruses and their role as drivers of ecosystem diversity are important contributors to the human oral microbiome in health and disease states.

Lessons learned and unlearned in periodontal microbiology

Periodontal diseases are initiated by bacterial species living in polymicrobial biofilms at or below the gingival margin and progress largely as a result of the inflammation elicited by specific subgingival species. In the past few decades, efforts to understand the periodontal microbiota have led to an exponential increase in information about biofilms associated with periodontal health and disease. In fact, the oral microbiota is one of the best-characterized microbiomes that colonize the human body. Despite this increased knowledge, one has to ask if our fundamental concepts of the etiology and pathogenesis of periodontal diseases have really changed. In this article we will review how our comprehension of the structure and function of the subgingival microbiota has evolved over the years in search of lessons learned and unlearned in periodontal microbiology. More specifically, this review focuses on: (i) how the data obtained through molecular techniques have impacted our knowledge of the etiology of periodontal infections; (ii) the potential role of viruses in the etiopathogenesis of periodontal diseases; (iii) how concepts of microbial ecology have expanded our understanding of host-microbe interactions that might lead to periodontal diseases; (iv) the role of inflammation in the pathogenesis of periodontal diseases; and (v) the impact of these evolving concepts on therapeutic and preventive strategies to periodontal infections. We will conclude by reviewing how novel systems-biology approaches promise to unravel new details of the pathogenesis of periodontal diseases and hopefully lead to a better understanding of their mechanisms.

Learned and unlearned concepts in periodontal diagnostics: a 50-year perspective

In the past 50 years, conceptual changes in the field of periodontal diagnostics have paralleled those associated with a better scientific understanding of the full spectrum of processes that affect periodontal health and disease. Fifty years ago, concepts regarding the diagnosis of periodontal diseases followed the classical pathology paradigm. It was believed that the two basic forms of destructive periodontal disease were chronic inflammatory periodontitis and 'periodontosis'- a degenerative condition. In the subsequent 25 years it was shown that periodontosis was an infection. By 1987, major new concepts regarding the diagnosis and pathogenesis of periodontitis included: (i) all cases of untreated gingivitis do not inevitably progress to periodontitis; (ii) progression of untreated periodontitis is often episodic; (iii) some sites with untreated periodontitis do not progress; (iv) a rather small population of specific bacteria ('periodontal pathogens') appear to be the main etiologic agents of chronic inflammatory periodontitis; and (v) tissue damage in periodontitis is primarily caused by inflammatory and immunologic host responses to infecting agents. The concepts that were in place by 1987 are still largely intact in 2012. However, in the decades to come, it is likely that new information on the human microbiome will change our current concepts concerning the prevention, diagnosis and treatment of periodontal diseases.

Short-chain fatty acids from periodontal pathogens suppress histone deacetylases, EZH2, and SUV39H1 to promote Kaposi's sarcoma-associated herpesvirus replication

Periodontal pathogens such as Porphyromonas gingivalis and Fusobacterium nucleatum produce five different short-chain fatty acids (SCFAs) as metabolic by-products. We detect significantly higher levels of SCFAs in the saliva of patients with severe periodontal disease. The different SCFAs stimulate lytic gene expression of Kaposi's sarcoma-associated herpesvirus (KSHV) dose dependently and synergistically. SCFAs inhibit class-1/2 histone deacetylases (HDACs) and downregulate expression of silent information regulator-1 (SIRT1). SCFAs also downregulate expression of enhancer of zeste homolog2 (EZH2) and suppressor of variegation 3-9 homolog1 (SUV39H1), which are two histone N-lysine methyltransferases (HLMTs). By suppressing the different components of host epigenetic regulatory machinery, SCFAs increase histone acetylation and decrease repressive histone trimethylations to transactivate the viral chromatin. These new findings provide mechanistic support that SCFAs from periodontal pathogens stimulate KSHV replication and infection in the oral cavity and are potential risk factors for development of oral Kaposi's sarcoma (KS).

IMPORTANCE

About 20% of KS patients develop KS lesions first in the oral cavity, while other patients never develop oral KS. It is not known if the oral microenvironment plays a role in oral KS tumor development. In this work, we demonstrate that a group of metabolic by-products, namely, short-chain fatty acids, from bacteria that cause periodontal disease promote lytic replication of KSHV, the etiological agent associated with KS. These new findings provide mechanistic support that periodontal pathogens create a unique microenvironment in the oral cavity that contributes to KSHV replication and development of oral KS.

EBV infection is common in gingival epithelial cells of the periodontium and worsens during chronic periodontitis

An amplifying role for oral epithelial cells (ECs) in Epstein-Barr Virus (EBV) infection has been postulated to explain oral viral shedding. However, while lytic or latent EBV infections of oro/nasopharyngeal ECs are commonly detected under pathological conditions, detection of EBV-infected ECs in healthy conditions is very rare. In this study, a simple non-surgical tissue sampling procedure was used to investigate EBV infection in the periodontal epithelium that surrounds and attaches teeth to the gingiva. Surprisingly, we observed that the gingival ECs of the periodontium (pECs) are commonly infected with EBV and may serve as an important oral reservoir of latently EBV-infected cells. We also found that the basal level of epithelial EBV-infection is significantly increased in chronic periodontitis, a common inflammatory disease that undermines the integrity of tooth-supporting tissues. Moreover, the level of EBV infection was found to correlate with disease severity. In inflamed tissues, EBV-infected pECs appear to be prone to apoptosis and to produce larger amounts of CCL20, a pivotal inflammatory chemokine that controls tissue infiltration by immune cells. Our discovery that the periodontal epithelium is a major site of latent EBV infection sheds a new light on EBV persistence in healthy carriers and on the role of this ubiquitous virus in periodontitis. Moreover, the identification of this easily accessible site of latent infection may encourage new approaches to investigate and monitor other EBV-associated disorders.

Higher prevalence of Epstein-Barr virus DNA in deeper periodontal pockets of chronic periodontitis in Japanese patients

Periodontitis, a complex chronic inflammatory disease caused by subgingival infection, is among the most prevalent microbial diseases in humans. Although traditional microbiological research on periodontitis has focused on putative bacteria such as Porphyromonas gingivalis, the herpes virus is proposed to be involved in the pathogenesis of periodontitis because bacterial etiology alone does not adequately explain various clinical aspects. In this study, we established for the first time, more Epstein–Barr virus (EBV) DNA is found deeper in periodontal pockets of chronic periodontitis in Japanese patients. Subgingival samples were collected from 85 patients with chronic periodontitis having two periodontal sites with probing depths (PD) of ≤3 mm (shallow) or ≥5 mm (deep) and were subjected to a nested polymerase chain reaction. EBV DNA was more frequently detected in patients with deeper PD sites (66%) than in those with shallow PD sites (48%) or healthy controls (45%). Coexistence of EBV DNA and P. gingivalis was significantly higher in patients with deeper PD sites (40%) than in those with shallow PD sites (14%) or healthy controls (13%). Although no difference in clinical index for periodontitis, the odds ratio of EBV DNA in patients with deeper PD sites was 2.36, which was 2.07-fold higher than that in those with shallow PD sites. Interestingly, the odds of acquiring chronic periodontitis (PD ≥5 mm) were higher in the presence of both EBV DNA and P. gingivalis compared with either EBV DNA or P. gingivalis only. In addition, we also observed that EBV-encoded small RNA (EBER) in positive cells of human gingival tissues. These results would suggest that EBV DNA may serve as a pathogenic factor leading to chronic periodontitis among Japanese patients.

Microbial sampling process can change results of microbiological analysis in periodontitis diagnosis. A minireview

This minireview aims to verify the supposition that the microbial sampling process can change results of microbiological analysis in periodontitis diagnosis. The literature search via Pubmed yielded 52 appropriate articles for analysis. Of which 38% (20/52) described that the sampling sites were isolated from saliva, whereas 62% (32/52) did not. Also, 29% (15/52) declared that the microbial sampling was performed before probing pocket depth (PPD), whereas 71% (37/52) did not. Comparison of the results of microbiological analysis in these studies showed that the bacteria most frequently detected in periodontal pockets was variable. Therefore, a sampling process that includes both the microbial sample being taken before PPD and saliva isolation of the sampling sites is needed to ensure the accuracy of microbiological analysis in periodontitis diagnosis.

The periodontal pathogen Porphyromonas gingivalis induces the Epstein-Barr virus lytic switch transactivator ZEBRA by histone modification

Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus that usually results in latent infection of B cells. The EBV BZLF1 gene product ZEBRA is a master regulator of the transition from latency to the lytic replication cycle. In the latent state, hypoacetylation of histone proteins in the BZLF1 promoter by histone deacetylases (HDACs) is primarily involved in maintaining EBV latency. Although the mechanism that regulates the switch between latency and lytic replication has been a central research focus in EBV infection, the causal link between HDAC inhibition and the disruption of viral latency is not well understood. Periodontal disease is a complex chronic inflammatory disease caused by subgingival infection with oral anaerobic bacteria, typically Porphyromonas gingivalis. Periodontal disease occurs worldwide and is among the most prevalent microbial diseases in humans. In this study, we examined the biological effect of P. gingivalis infection on EBV reactivation and found that P. gingivalis induced expression of ZEBRA. This activity was associated with supernatant from bacterial culture, but not with other bacterial components such as lipopolysaccharide or fimbriae. We demonstrated that culture supernatant from P. gingivalis, which contained high concentrations of butyric acid, inhibited HDACs, thus increasing histone acetylation and the transcriptional activity of the BZLF1 gene. Chromatin immunoprecipitation assays revealed that HDACs were present in the BZLF1 promoter during latent state and that they were dissociated from the promoter concomitantly with the association of acetylated histone H3, upon stimulation by culture supernatant from P. gingivalis. Thus, P. gingivalis induced EBV reactivation via chromatin modification, and butyric acid-a bacterial metabolite-was responsible for this effect. These findings suggest that periodontal disease is a risk factor for EBV reactivation in infected individuals and might therefore contribute to progression of EBV-related diseases.

Periodontal disease may associate with breast cancer

The main purpose was to evaluate the association between periodontal disease and the incidence of breast cancer in a prospective study of 3273 randomly selected subjects aged 30-40 years at baseline. Breast cancer incidence was registered from 1985 to 2001 according to the WHO International Classification of Diseases criteria. At baseline, 1676 individuals also underwent a clinical oral examination (Group A) whereas 1597 subjects were not clinically examined but were registered (Group B). The associations between breast cancer, periodontal disease, and missing molars were determined using multiple logistic regression models with several background variables and known risk factors for cancer. In total 26 subjects in group A and 15 subjects in group B had breast cancer. The incidence of breast cancer was 1.75% in subjects who had periodontal disease and/or any missing molars, and 0 in subjects who had periodontal disease but had no missing molars. For periodontally healthy subjects with no missing teeth the breast cancer incidence was 1%. For group B the respective incidence was 0.94%. Female gender (odds ratio (OR) 13.08) and missing any molar in the mandible (OR 2.36) were explanatory variables for breast cancer. Of the subjects with periodontal disease and any missing molars in the mandible 5.5% had breast cancer in comparison to 0.5% of the subjects who had periodontal disease but no missing molars in the mandible (P < 0.02). Chronic periodontal disease indicated by missing molars seemed to associate statistically with breast cancer.