Oral microbiota and systemic disease

Effect of Probiotic Supplements on the Oral Microbiota-A Narrative Review

Data from systematic reviews and meta-analyses show that probiotics positively impact clinical parameters of oral diseases such as gingivitis, dental caries, and periodontitis. However, the working mechanism of probiotics is not fully understood, but is hypothesized to be mediated by direct and indirect interactions with the oral microbiota and the human host. In the present narrative review, we focused on the microbiological effect of probiotic supplements based on data retrieved from randomized clinical trials (RCTs). In addition, we assessed to what extent contemporary molecular methods have been employed in clinical trials in the field of oral probiotics. Multiple RCTs have been performed studying the potential effect of probiotics on gingivitis, dental caries, and periodontitis, as evaluated by microbial endpoints. In general, results are conflicting, with some studies reporting a positive effect, whereas others are not able to record any effect. Major differences in terms of study designs and sample size, as well as delivery route, frequency, and duration of probiotic consumption, hamper comparison across studies. In addition, most RCTs have been performed with a limited sample size using relatively simple methods for microbial identification, such as culturing, qPCR, and DNA-DNA checkerboard, while high-throughput methods such as 16S sequencing have only been employed in a few studies. Currently, state-of-the-art molecular methods such as metagenomics, metatranscriptomics, and metaproteomics have not yet been used in RCTs in the field of probiotics. The present narrative review revealed that the effect of probiotic supplements on the oral microbiota remains largely uncovered. One important reason is that most RCTs are performed without studying the microbiological effect. To facilitate future systematic reviews and meta-analyses, an internationally agreed core outcome set for the reporting of microbial endpoints in clinical trials would be desirable. Such a standardized collection of outcomes would most likely improve the quality of probiotic research in the oral context.

Advances in periodontal biomarkers

Due to technologic advancements, periodontology has witnessed a boost in biomarker research over the past three decades. Indeed, with the aid of omics, our understanding of the healthy periodontium, pathogenesis of periodontal diseases, and healing after periodontal treatment has improved significantly. Yet, the traditional methods, periodontal probing and radiographies, remain the most common methods to diagnose periodontal disease and monitor treatment. Although these approaches can produce reliable diagnostic outcomes, they generally detect disease only after significant tissue degradation thus making treatment outcome highly uncertain. Accordingly, laboratories worldwide have collaborated with clinicians to design accurate, rapid and cost-effective biomarkers for periodontal disease diagnosis. Despite these efforts, biomarkers that can be widely used in early disease diagnosis and for treatment outcome prediction are far from daily use. The aim of this chapter is to give a general overview on periodontal health and diseases, and review recent advancements in periodontal biomarker research. A second aim will discuss the strengths and limitations of translating periodontal biomarker research to clinical practice. Genetic biomarkers of periodontitis are not discussed as the available confirmatory data is scarce.

Filifactor alocis enhances survival of Porphyromonas gingivalis W83 in response to H2 O2 -induced stress

A dysbiotic microbial community whose members have specific/synergistic functions that are modulated by environmental conditions, can disturb homeostasis in the subgingival space leading to destructive inflammation, plays a role in the progression of periodontitis. Filifactor alocis, a gram-positive, anaerobic bacterium, is a newly recognized microbe that shows a strong correlation with periodontal disease. Our previous observations suggested F. alocis to be more resistant to oxidative stress compared to Porphyromonas gingivalis. The objective of this study is to further determine if F. alocis, because of its increased resistance to oxidative stress, can affect the survival of other 'established' periodontal pathogens under environmental stress conditions typical of the periodontal pocket. Here, we have shown that via their interaction, F. alocis protects P. gingivalis W83 under H2 O2 -induced oxidative stress conditions. Transcriptional profiling of the interaction of F. alocis and P. gingivalis in the presence of H2 O2 -induced stress revealed the modulation of several genes, including those with ABC transporter and other cellular functions. The ABC transporter operon (PG0682-PG0685) of P. gingivalis was not significant to its enhanced survival when cocultured with F. alocis under H2 O2 -induced oxidative stress. In F. alocis, one of the most highly up-regulated operons (FA0894-FA0897) is predicted to encode a putative manganese ABC transporter, which in other bacteria can play an essential role in oxidative stress protection. Collectively, the results may indicate that F. alocis could likely stabilize the microbial community in the inflammatory microenvironment of the periodontal pocket by reducing the oxidative environment. This strategy could be vital to the survival of other pathogens, such as P. gingivalis, and its ability to adapt and persist in the periodontal pocket.

Effect of scaling and root planing with and without minocycline HCl microspheres on periodontal pathogens and clinical outcomes: A randomized clinical trial

BACKGROUND

This study tests the effects of scaling and root planing (SRP) versus SRP plus minocycline hydrochloride microspheres (SRP+MM) on 11 periodontal pathogens and clinical outcomes in Stage II-IV Grade B periodontitis participants.

METHODS

Seventy participants were randomized to receive SRP (n = 35) or SRP+MM (n = 35). Saliva and clinical outcomes were collected for both groups at baseline before SRP, 1-month reevaluation, and at 3- and 6-month periodontal recall. MM were delivered to pockets ≥5 mm immediately after SRP and immediately after the 3-month periodontal maintenance in the SRP+MM group. A proprietary saliva test* was utilized to quantitate 11 putative periodontal pathogens. Microorganisms and clinical outcomes were compared between groups using generalized linear mixed-effects models with fixed effects and random effects terms. Mean changes from baseline were compared between groups via group-by-visit interaction tests.

RESULTS

Significant reduction in Tannerella forsythia, Treponema denticola, Fusobacterium nucleatum, Prevotella intermedia, Parvimonas micra, and Eikenella corrodens were identified at the 1-month reevaluation after SRP+MM. Six months after SRP with a re-application of MM 3 months after SRP, Fusobacterium nucleatum, Prevotella intermedia, Campylobacter rectus, and Eikenella corrodens were significantly reduced. SRP+MM participants had significant clinical outcome reductions in pockets ≥5 mm at the reevaluation, 3- and 6-month periodontal maintenance, and clinical attachment loss gains at the 6-month periodontal maintenance.

CONCLUSION

MM delivered immediately after SRP and reapplication at 3 months appeared to contribute to improved clinical outcomes and sustained decreased numbers of Fusobacterium nucleatum, Prevotella intermedia, Campylobacter rectus, and Eikenella corrodens at 6 months.

A retrospective study comparing oral health in cancer patients and healthy people

The purpose of this study was to investigate the relationship between oral and dental health in cancer patients and control group, which was conducted in Tabriz Shahid Gazi hospital. A researchers-made and validated questionnaire including oral and dental health criteria, was filled by the cancer patients (201 cases) and healthy controls (199 cases). Then, the results of the study were analyzed by SPSS software, and reported as Odds ratios (95 % confidence intervals) in tow groups. The results indicate that comparison of filled tooth, tooth extraction, dental caries, and gingival problems including bleeding, gum surgery and inflammation in cancer and controls were significantly meaningful. However, the comparison between the two groups was not significant in terms of the type of the tooth (natural or denture) and the number of daily toothbrushes, but they were considered as risk factors due to statistical results. Environmental factors, and especially oral hygiene, can play an important role in the incidence of different cancers. Among these, the type of oral microorganisms, and their overgrowth and released antigens should be studied further in the emergence of different kinds of cancer in humans.

The Plausible Relationship Between Periodontitis and Glaucoma

Periodontitis has been associated with several medical conditions. For some of these medical conditions, periodontitis has been hypothesized to share important pathogenic mechanisms with other systemic conditions affecting the body. Recently, advances in technology have led to the identification of novel inflammatory mediators implicated in some chronic medical conditions associated with periodontitis. The potential identification of these systemic inflammatory mediators in periodontitis would offer additional support to the potential periodontal-systemic disease association. In recent years, the term oral foci of infection has attained an upturn in terms of systemic morbidities, while finite scrutinization indicates the implication of chronic oral inflammation in the pathogenesis of eye diseases. Initially, there is a singularity for the mechanistic understanding of the reported link between periodontal diseases and ocular comorbidities. There is a limited number of scientific evidence in the literature that suggests a relationship between glaucoma and periodontitis, and they share a common pathway/link based on inflammatory markers. Based on a molecular biological technique, it was believed by researchers and clinicians that eye diseases were a result of oral infections. Furthermore, this review will try to focus on the concept of oral dysbiosis in the progression of inflammatory eye diseases such as diabetic retinopathy, scleritis, uveitis, glaucoma, and age-related macular degeneration (AMD).

One Third of Patients before Endoprosthesis Implantation Show an Oral Focus as Potential Source of Infectious Complication—The Value of Pre-Operative Dental Risk Stratification in a German Cohort

Objective: The aim of this cross-sectional cohort study was to evaluate a comprehensive dental examination and referral concept for patients prior to endoprosthesis (EP) implantation in an interdisciplinary setting. Methods: Patients, who were prepared for EP surgery in the clinic for orthopaedics, were referred to the dental clinic for a dental examination. Thereby, dental and periodontal treatment need, radiographic and temporomandibular joint findings were assessed. Based on oral and radiographic investigation, a risk classification for potential source of prosthetic infection was performed. If potential oral foci of EP infection were present (e.g., apically radiolucent teeth, severe periodontitis or additional inflammatory findings), patients were classified as at high risk for EP infection with oral origin. Those individuals were allocated to their family dentist or special clinic for dental treatment prior to EP surgery. Results: A total of 311 patients were included (mean age: 67.84 ± 10.96 years, 51% male). A dental treatment need of 33% was found, while the periodontal treatment need was 83%. Thirty-one percent of patients showed at least one apical radiolucency (a sign of chronic infection/inflammation). Furthermore, additional findings such as radiographic signs of sinusitis maxillaris were found in 24% of patients. Temporomandibular disease was probable in 17% of individuals. One-third (34%) were assigned to the high risk group for an EP infection with oral origin. Conclusion: German patients before EP have a high periodontal treatment need and show frequently (34%) a potential oral focus of infection, underlining the necessity of including dental examination and risk stratification as part of the pre-operative assessment prior to EP implantation. Therefore, an approach as applied in this study appears reasonable for those individuals.

CTHRC1 expressed in periodontitis and human periodontal fibroblasts exposed to inflammatory stimuli

OBJECTIVES

Collagen triple helix repeat containing-1 (CTHRC1) is a glycoprotein that can be secreted extracellularly and is involved in the regulation of collagen matrix in a variety of diseases. The expression level of CTHRC1 in periodontitis was detected in the present study.

MATERIALS AND METHODS

The gingival tissues from clinically healthy subjects (15 cases) and those with periodontitis (30 cases) were taken for immunohistochemical staining. Lipopolysaccharide of the Porphyromonas gingivalis was added in the periodontal ligament fibroblast culture in vitro. Cells were collected and the mRNA levels of the intracellular CTHRC1 and protein expression of the extracellular CTHRC1 were detected.

RESULTS

The protein expression of CTHRC1 in the periodontitis group was higher than that of the clinically healthy group. The in vitro cell experiments showed that 10 μg/mL of P.g LPS could induce a significant increase in protein secretion of CTHRC1, and 5 μg/mL P.g LPS had a significant effect on promoting the mRNA expression of CTHRC1.

CONCLUSION

CTHRC1 might be involved in the development of periodontitis and the expression level might be significantly correlated with the stimulation of P.g LPS on fibroblasts. Different stimulation intensities of P.g LPS might result in different expression patterns of CTHRC1.

Role of the Filifactor alocis Hypothetical Protein FA519 in Oxidative Stress Resistance

In the periodontal pocket, there is a direct correlation between environmental conditions, the dynamic oral microbial flora, and disease. The relative abundance of several newly recognized microbial species in the oral microenvironment has raised questions on their impact on disease development. One such organism, Filifactor alocis, is significant to the pathogenic biofilm structure. Moreover, its pathogenic characteristics are highlighted by its ability to survive in the oxidative-stress microenvironment of the periodontal pocket and alter the microbial community dynamics. There is a gap in our understanding of its mechanism(s) of oxidative stress resistance and impact on pathogenicity. Several proteins, including HMPRFF0389-00519 (FA519), were observed in high abundance in F. alocis during coinfection of epithelial cells with Porphyromonas gingivalis W83. Bioinformatics analysis shows that FA519 contains a "Cys-X-X-Cys zinc ribbon domain" which could be involved in DNA binding and oxidative stress resistance. We have characterized FA519 to elucidate its roles in the oxidative stress resistance and virulence of F. alocis. Compared to the wild-type strain, the F. alocis isogenic gene deletion mutant, FLL1013 (ΔFA519::ermF), showed significantly reduced sensitivity to hydrogen peroxide and nitric oxide-induced stress. The ability to form biofilm and adhere to and invade gingival epithelial cells was also reduced in the isogenic mutant. The recombinant FA519 protein was shown to protect DNA from Fenton-mediated damage with an intrinsic ability to reduce hydrogen peroxide and disulfide bonds. Collectively, these results suggest that FA519 is involved in oxidative stress resistance and can modulate important virulence attributes in F. alocis. IMPORTANCE Filifactor alocis is an emerging member of the periodontal community and is now proposed to be a diagnostic indicator of periodontal disease. However, due to the lack of genetic tools available to study this organism, not much is known about its virulence attributes. The mechanism(s) of oxidative stress resistance in F. alocis is unknown. Therefore, identifying the adaptive mechanisms utilized by F. alocis to survive in the oxidative stress environment of the periodontal pocket would lead to understanding its virulence regulation, which could help develop novel therapeutic treatments to combat the effects of periodontal disease. This study is focused on the characterization of FA519, a hypothetical protein in F. alocis, as a multifunctional protein that plays an important role in the reactive oxygen species-detoxification pathway. Collectively, our results suggest that FA519 is involved in oxidative stress resistance and can modulate important virulence attributes in F. alocis.

The Effect of Brilliant Blue-Based Plaque-Staining Agents on Aesthetic Orthodontic Appliances

Orthodontic appliances discolour over treatment time, and a yellowish plaque builds up on the contact area of the brackets, adhesive and teeth. Brilliant Blue-based plaque-staining agents (BBPSAs), which increase tooth brushing efficiency, have the potential to support the maintenance of proper oral hygiene during orthodontic treatment. However, they exhibit strong colouring properties, and their impact on the aesthetics of braces remains unclear. Therefore, the aim of this study was to investigate the influence of commercially available BBPSAs on the colour of aesthetic orthodontic materials. A light-cured, colour-changing orthodontic adhesive and new-generation, monocrystalline, sapphire brackets were chosen for the experiments. The effect of the staining agent on the tested materials was investigated in terms of the reaction temperature and time, as well as the presence of black tea-induced impurities on the materials. The CIELAB (Commission Internationale de L'éclairage L* a* b*) colour system parameters were measured, and the colour differences (ΔE*ab and ΔE00-the Commission Internationale de L'éclairage 2000 colour-difference) were determined for the materials under several experimental conditions. The braces' green-red colour expression was positively affected by the BBPSA. Under in vitro conditions, the regular use of the BBPSA for 90 days visibly improved the unfavourable colour change caused by the black tea.

Metagenomic evidence for a polymicrobial signature of sepsis

Our understanding of the host component of sepsis has made significant progress. However, detailed study of the microorganisms causing sepsis, either as single pathogens or microbial assemblages, has received far less attention. Metagenomic data offer opportunities to characterize the microbial communities found in septic and healthy individuals. In this study we apply gradient-boosted tree classifiers and a novel computational decontamination technique built upon SHapley Additive exPlanations (SHAP) to identify microbial hallmarks which discriminate blood metagenomic samples of septic patients from that of healthy individuals. Classifiers had high performance when using the read assignments to microbial genera [area under the receiver operating characteristic (AUROC=0.995)], including after removal of species ‘culture-confirmed’ as the cause of sepsis through clinical testing (AUROC=0.915). Models trained on single genera were inferior to those employing a polymicrobial model and we identified multiple co-occurring bacterial genera absent from healthy controls. While prevailing diagnostic paradigms seek to identify single pathogens, our results point to the involvement of a polymicrobial community in sepsis. We demonstrate the importance of the microbial component in characterising sepsis, which may offer new biological insights into the aetiology of sepsis, and ultimately support the development of clinical diagnostic or even prognostic tools.

Salivary markers and coronavirus disease 2019: insights from cross-talk between the oral microbiome and pulmonary and systemic low-grade inflammation and implications for vascular complications

To date, coronavirus disease 2019 (COVID-19) has affected over 6.2 million individuals worldwide, including 1.46 million deaths. COVID-19 complications are mainly induced by low-grade inflammation-causing vascular degeneration. There is an increasing body of evidence that suggests that oral dysbiotic taxa are associated with worse prognosis in COVID-19 patients, especially the Prevotella genus, which was retrieved from nasopharyngeal and bronchoalveolar lavage samples in affected patients. Oral dysbiosis may act by increasing the likelihood of vascular complications through low-grade inflammation, as well as impairing respiratory mucosal barrier mechanisms against SARS-CoV-2. Salivary markers can be used to reflect this oral dysbiosis and its subsequent damaging effects on and the lungs and vasculature. Salivary sampling can be self-collected, and is less costly and less invasive, and thus may be a superior option to serum markers in risk stratification of COVID-19 patients. Prospective studies are needed to confirm such hypothesis. Video Abstract: http://links.lww.com/CAEN/A28.

Identification of Substances Produced by Cercospora brachiata in Absence of Light and Evaluation of Antibacterial Activity

Cercospora brachiata is a phytopathogenic fungus. To know more about the metabolites produced by this fungus, the objective of this work was to identify, isolate and characterize substances present in extracts of the growth broth and mycelium, using gas chromatography with mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR). It was also objective to evaluate the antibacterial activity of the extracts. Among the compounds identified, fatty acids, esters, and steroids can be highlighted. The main compounds identified are 9-hexadecenoic, hexadecenoic, oleic, octadecanoic, lauric, myristic, palmitic, doceno-13-enoic, stearic, linoleic, and nonadecanoic acids present in almost all extracts. For the antibacterial activity, the broth microdilution method was used. The ethyl acetate extract of the mycelium presented inhibitory concentrations (MICs) against the bacterium Actinomyces naeslundii (100 μg mL^-1) and Streptococcus sanguinis (200 μg mL^-1). Finally, two steroids were isolated and identified in the hexane extract of mycelium: ergosta-6,22-dien-3β,5α,8α-triol and brassicasterol.

Comparison of Microbiome in Stimulated Saliva in Edentulous and Dentate Subjects

Measurement of saliva microbes is promoted as a way to detect oral and systemic disease, yet there is a multitude of factors that affect the oral microbiome. The salivary microbiome is influenced by biofilm of shedding (epithelial) and non-shedding (tooth) surfaces. Methods for study of the salivary microbiome are by no means standardized, and differences in sample collection, storage, and processing can all affect results to some degree. Here we describe one method of saliva collection that has been validated for reproducibility. Standard 16S rRNA gene analysis is done using the Human Oral Microbiome Database library which results in analysis that is straightforward. Everything about this procedure except the library synthesis and DNA sequencing itself can easily be done in-house. To gauge the ability of salivary microbial analytics to distinguish between edentulous and dentate oral conditions, differences in the saliva microbiome of subjects with and without teeth were examined. Fifty-two dentate and 49 edentulous subjects provided stimulated saliva samples. 16S rRNA gene sequencing, QIIME-based data processing, and statistical analysis were done using several different analytical approaches to detect differences in the salivary microbiome between the two groups. Bacteria diversity was lower in the edentulous group. Remarkably, all 31 of the most significant differences in taxa were deficits that occurred in the edentulous group. As one might expect, many of these taxa are attributed to dental plaque and gingival sulcus-associated bacteria verifying that the measurement of 16S rRNA genes in the bacteria of the saliva can be used to reproducibly measure expected differences in the oral microbiome that occur with edentulism or other conditions and diseases.

Metabolic plasticity enables lifestyle transitions of Porphyromonas gingivalis

Our understanding of how the oral anaerobe Porphyromonas gingivalis can persist below the gum line, induce ecological changes, and promote polymicrobial infections remains limited. P. gingivalis has long been described as a highly proteolytic and asaccharolytic pathogen that utilizes protein substrates as the main source for energy production and proliferation. Here, we report that P. gingivalis displays a metabolic plasticity that enables the exploitation of non-proteinaceous substrates, specifically the monocarboxylates pyruvate and lactate, as well as human serum components, for colonization and biofilm formation. We show that anabolism of carbohydrates from pyruvate is powered by catabolism of amino acids. Concomitantly, the expression of fimbrial adhesion is upregulated, leading to the enhancement of biofilm formation, stimulation of multispecies biofilm development, and increase of colonization and invasion of the primary gingival epithelial cells by P. gingivalis. These studies provide the first glimpse into the metabolic plasticity of P. gingivalis and its adaptation to the nutritional condition of the host niche. Our findings support the model that in response to specific nutritional parameters, P. gingivalis has the potential to promote host colonization and development of a pathogenic community.

A clinical nomogram incorporating salivary Desulfovibrio desulfuricans level and oral hygiene index for predicting colorectal cancer

Background

Emerging evidence demonstrates that the salivary microbiome could serve as a biomarker for various diseases. To date, the oral microbiome’s role in the diagnosis of colorectal cancer (CRC) has not been fully elucidated. We aimed to illustrate the salivary microbiome’s role in diagnosing and predicting the risk of CRC.

Methods

We collected preoperational saliva from 237 patients [95 healthy controls (HCs) and 142 CRC patients] who underwent surgical resections or colorectal endoscopy in Renji Hospital from January 2018 to January 2020. Clinical demographics, comorbidities, and oral health conditions were obtained from medical records or questionnaires. Salivary microbial biomarkers were detected using quantitative polymerase chain reaction (qPCR) after DNA extraction. Multivariate logistic regression analysis was employed to analyze the risk factors for CRC. A predictive model for the risk of developing CRC was constructed based on logistic regression analysis. Predictive accuracy was internally validated by bootstrap resampling. A clinical nomogram was constructed to visualize the predictive model.

Results

Logistic regression analysis demonstrated that the risk factors associated with CRC included age at diagnosis, male sex, poor oral hygiene, and relative salivary Desulfovibrio desulfuricans abundance. The predictive model had good discriminative (0.866) and calibration abilities (0.834) after bias correction.

Conclusions

The model based on age, sex, oral hygiene index (OHI), and the salivary Desulfovibrio desulfuricans level, which is visualized by a clinical nomogram, can predict the risk of CRC. Developing good oral hygiene habits might reduce the risk of CRC.

Significant aspects and correlation between glycemic control and generalized chronic periodontitis in type 2 diabetes mellitus patients

The purpose of this research was to assess the correlation between glycemic control and clinical periodontal characteristics in type 2 diabetics with generalized chronic periodontitis. A total of 182 patients with type 2 diabetes mellitus and generalized chronic periodontitis were included in our study. The clinical examination included full-mouth plaque accumulation, bleeding on probing (BoP), probing depth (PD), presence of suppuration (SUP), clinical attachment level (CAL) and number of remaining teeth. Blood analyses were conducted for glycated hemoglobin (HbA1c) and fasting plasma glucose (FPG). The correlation between the extent of periodontitis, defined as the percentage of PD and CAL sites ≥5 mm, and glycemic control was also analyzed. In addition, clinical parameters were compared between two (<7 and ≥7%) glycemic subsets. The frequency of uncontrolled diabetic subjects (HbA1c ≥7%) was higher than that of the well-controlled subjects (HbA1c <7%), 57.15 vs. 42.85%. Among the clinical parameters evaluated, mean full-mouth plaque accumulation was significantly higher among patients without glucose control (74.2±25.2 vs. 62.5±28.7%, P<0.01), as well as mean PD (3.78±0.9 vs. 3.42±0.8 mm, P<0.01) and mean CAL (4.5±1.2 vs. 4.1±1.2 mm, P=0.02). The sites with PD ≥5 mm were statistically more prevalent among patients with HbA1c ≥7% compared with patients with HbA1c <7% (27.8±6.2 vs. 23.4±5.8%, P<0.01). The mean number of remaining teeth was statistically significantly lower in patients with HbA1c ≥7% compared with patients with HbA1c <7% (18.5±3.2 vs. 20.4±4.1, P<0.01). In conclusion, the severity and extension of generalized chronic periodontitis was higher in type 2 diabetes mellitus patients with poor glucose control compared with those with good glucose control.

Oral Dysbiosis and Inflammation in Parkinson's Disease

Background:

Oral microbiota has largely escaped attention in Parkinson’s disease (PD), despite its pivotal role in maintaining oral and systemic health.

Objective:

The aim of our study was to examine the composition of the oral microbiota and the degree of oral inflammation in PD.

Methods:

Twenty PD patients were compared to 20 healthy controls. Neurological, periodontal and dental examinations were performed as well as dental scaling and gingival crevicular fluid sampling for cytokines measurement (interleukine (IL)-1β, IL-6, IL-1 receptor antagonist (RA), interferon-γ and tumor necrosis factor (TNF)-α). Two months later, oral microbiota was sampled from saliva and subgingival dental plaque. A 16S rRNA gene amplicon sequencing was used to assess bacterial communities.

Results:

PD patients were in the early and mid-stage phases of their disease (Hoehn & Yahr 2–2.5). Dental and periodontal parameters did not differ between groups. The levels of IL-1β and IL-1RA were significantly increased in patients compared to controls with a trend for an increased level of TNF-α in patients. Both saliva and subgingival dental plaque microbiota differed between patients and controls. Streptococcus mutans, Kingella oralis, Actinomyces AFQC_s, Veillonella AFUJ_s, Scardovia, Lactobacillaceae, Negativicutes and Firmicutes were more abundant in patients, whereas Treponema KE332528_s, Lachnospiraceae AM420052_s, and phylum SR1 were less abundant.

Conclusion:

Our findings show that the oral microbiome is altered in early and mid-stage PD. Although PD patients had good dental and periodontal status, local inflammation was already present in the oral cavity. The relationship between oral dysbiosis, inflammation and the pathogenesis of PD requires further study.

Oral health-related quality of life in patients with heart failure and left ventricular assist devices-results of a cross-sectional study

Objectives

The aim of this cross-sectional study was to compare oral health-related quality of life (OHRQoL) of patients with left ventricular assist device (LVAD) and heart failure (HF).

Material and methods

Seventy-four patients with LVAD were recruited from University Department for Cardiac Surgery, Leipzig Heart Center, Germany. A group of 72 patients with HF was composed by matching (age, gender, smoking). The German short form of oral health impact profile (OHIP G14) was applied. Health-related quality of life (HRQoL) was measured by short form 36 survey (SF-36). Dental conditions (decayed-, missing- and filled-teeth [DMF-T]), remaining teeth and periodontal findings were assessed. Statistics: t-test, Mann-Whitney U test, Kruskal-Wallis test, chi-square or Fisher test, linear regression.

Results

Age, gender, smoking, underlying disease, co-morbidities and oral findings were comparable between groups (p > 0.05). OHIP G14 sum score was 3.53 ± 6.82 (LVAD) and 2.92 ± 5.35 (HF; p = 0.70), respectively. The scales SF-36 physical functioning (p = 0.05) and SF-36 social functioning (p < 0.01) were worse in LVAD. In the LVAD group, the DMF-T and remaining teeth negatively correlated with OHIP G14 sum score (p < 0.01). In HF patients, positive correlations were found between OHIP G14 and D-T (p < 0.01) and remaining teeth (p = 0.04). Moreover, DMF-T (p = 0.03) and remaining molars/premolars (p = 0.02) were negatively correlated with SF-36 scales in HF.

Conclusions

Oral health and OHRQoL was comparable between LVAD and HF; thereby, OHRQoL reflected the clinical oral status.

Clinical relevance

Dental care, with beginning in early stage of HF, should be fostered to preserve teeth and support quality of life before and after LVAD implantation.

Starvation Survival and Biofilm Formation under Subminimum Inhibitory Concentration of QAMs

Quaternary ammonium methacrylates (QAMs) are useful antimicrobial compounds against oral bacteria. Here, we investigated the effects of two QAMs, dimethylaminododecyl methacrylate (DMADDM) and dimethylaminohexadecyl methacrylate (DMAHDM), on biofilm formation, survival and development of tolerance by biofilm, and survival and development of tolerance against QAMs after prolonged starvation. Enterococcus faecalis (E. faecalis), Streptococcus gordonii (S. gordonii), Lactobacillus acidophilus (L. acidophilus), and Actinomyces naeslundii (A. naeslundii) were used. Minimum inhibitory concentration (MIC) of QAMs against multispecies biofilm was determined. Biofilm formed under sub-MIC was observed by crystal violet staining and confocal laser scanning microscopy (CLSM). Metabolic activity was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and lactic acid production measurement. Development of tolerance was determined by MIC values before and after exposure to QAMs or after prolonged starvation. It was found that E. faecalis and S. gordonii could survive and form biofilm under sub-MIC of QAMs. Lactic acid production from biofilms formed under sub-MIC was significantly higher than control specimens (p < 0.05). The exposure to sub-MIC of QAMs promoted biofilm formation, and prolonged starvation or prolonged contact with sub-MIC helped bacteria develop tolerance against killing by QAMs.

The Use of MALDI-TOF Mass Spectrometry to Analyze Commensal Oral Yeasts in Nursing Home Residents

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a rapid and accurate method to identify microorganisms in clinical laboratories. This study isolates yeast-like microorganisms in the oral washes that are collected from non-bedridden nursing home residents, using CHROMagar Candida plates, and identifies them using Bruker MALDI-TOF MS. The ribosomal DNA sequences of the isolates are then examined. Three hundred and twenty yeast isolates are isolated from the oral washes. Candida species form the majority (78.1%), followed by Trichosporon/Cutaneotrichosporon species (8.8%). Bruker MALDI-TOF MS gives a high-level confidence, with a log(score) value of ≥1.8, and identifies 96.9% of the isolates. There are six inconclusive results (1.9%), and those sequences are verified as rare clinical species, including Candida ethanolica, Cutaneotrichosporon jirovecii, Exophiala dermatitidis, and Fereydounia khargensis. Almost all of the isolates have a regular color on the CHROMagar Candida plates. If the colonies are grouped by color on the plates, a specific dominant yeast species is present in each color group, except for purple or orange isolates. In conclusion, MALDI-TOF MS is verified as a fast, accurate and practical method to analyze oral yeasts in elderly subjects.

Separation of Glycosylated OmpA-Like Proteins from Porphyromonas gingivalis and Tannerella forsythia

OmpA-like proteins located in the outer bacterial membrane are potential virulence factors from the major periodontal pathogens Porphyromonas gingivalis and Tannerella forsythia. Our previous studies have shown that OmpA-like proteins are glycosylated by O-linked N-acetylglucosamine (O-GlcNAc) and are strongly reactive to wheat germ agglutinin (WGA) lectin, which shows sugar specificity to GlcNAc. Utilizing this property, we have developed a separation method for OmpA-like proteins by affinity chromatography using WGA lectin-agarose. The purity of enriched native OmpA-like proteins were confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Coomassie Brilliant Blue (CBB) staining. More importantly, the purified OmpA-like proteins formed a unique trimeric structure keeping their bioactivity intact. In this chapter, we describe a detailed procedure to separate OmpA-like proteins, which may be used to further progress the biological studies of OmpA-like proteins.

Relationship between Periodontitis and Glaucoma: A Cross-Sectional Study

The objective of this cross-sectional study was to evaluate the association between periodontitis and glaucoma. This prospective cohort study used epidemiological data from the Korean Genome and Epidemiology Study performed between 2004 and 2016. Among 173,209 participants, 9572 patients with periodontitis and 115,332 controls (nonperiodontitis) were selected. We analysed the history of glaucoma in periodontitis and control participants. The participants were interviewed regarding their history of hypertension, diabetes mellitus, hyperlipidaemia, periodontitis, glaucoma, smoking, and alcohol consumption by trained interviewers. A logistic regression model was created to analyse the odds ratio of having a history of glaucoma among patients with periodontitis. Two-tailed analyses using chi-square and independent t-tests were used for statistical analysis. The adjusted odds ratio of periodontitis as a risk factor for glaucoma was 3.44 (95% confidence interval = 2.99–3.97, $p<0.001$ ). This study demonstrated that glaucoma was associated with periodontitis.

Heme Competition Triggers an Increase in the Pathogenic Potential of Porphyromonas gingivalis in Porphyromonas gingivalis-Candida albicans Mixed Biofilm

As one of the main pathogens of periodontitis, Porphyromonas gingivalis often forms mixed biofilms with other bacteria or fungi under the gingiva, such as Candida albicans. Heme is an important iron source for P. gingivalis and C. albicans that supports their growth in the host. From the perspective of heme competition, this study aims to clarify that the competition for heme enhances the pathogenic potential of P. gingivalis during the interaction between P. gingivalis and C. albicans. Porphyromonas gingivalis single-species biofilm and P. gingivalis-C. albicans dual-species biofilm were established in a low- and high-heme environment. The results showed that the vitality of P. gingivalis was increased in the dual-species biofilm under the condition of low heme, and the same trend was observed under a laser confocal microscope. Furthermore, the morphological changes in P. gingivalis were observed by electron microscope, and the resistance of P. gingivalis in dual-species biofilm was stronger against the killing effect of healthy human serum and antibiotics. The ability of P. gingivalis to agglutinate erythrocyte was also enhanced in dual-species biofilm. These changes disappeared when heme was sufficient, which confirmed that heme competition was the cause of thepathogenicy change in P. gingivalis. Gene level analysis showed that P. gingivalis was in a superior position in the competition relationship by increasing the expression of heme utilization-related genes, such as HmuY, HmuR, HusA, and Tlr. In addition, the expression of genes encoding gingipains (Kgp, RgpA/B) was also significantly increased. They not only participate in the process of utilizing heme, but also are important components of the virulence factors of P. gingivalis. In conclusion, our results indicated that the pathogenic potential of P. gingivalis was enhanced by C. albicans through heme competition, which ultimately promoted the occurrence and development of periodontitis and, therefore, C. albicans subgingival colonization should be considered as a factor in assessing the risk of periodontitis.

Complex Interaction between Resident Microbiota and Misfolded Proteins: Role in Neuroinflammation and Neurodegeneration

Neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD) and Creutzfeldt-Jakob disease (CJD) are brain conditions affecting millions of people worldwide. These diseases are associated with the presence of amyloid-β (Aβ), alpha synuclein (α-Syn) and prion protein (PrP) depositions in the brain, respectively, which lead to synaptic disconnection and subsequent progressive neuronal death. Although considerable progress has been made in elucidating the pathogenesis of these diseases, the specific mechanisms of their origins remain largely unknown. A body of research suggests a potential association between host microbiota, neuroinflammation and dementia, either directly due to bacterial brain invasion because of barrier leakage and production of toxins and inflammation, or indirectly by modulating the immune response. In the present review, we focus on the emerging topics of neuroinflammation and the association between components of the human microbiota and the deposition of Aβ, α-Syn and PrP in the brain. Special focus is given to gut and oral bacteria and biofilms and to the potential mechanisms associating microbiome dysbiosis and toxin production with neurodegeneration. The roles of neuroinflammation, protein misfolding and cellular mediators in membrane damage and increased permeability are also discussed.

Bacteria associated with periodontal disease are also increased in health

Background

The objective of this cross-sectional clinical study was to analyze the differences in the microbiome in gingival sulci of adult patients in the presence or absence of chronic periodontitis.

Material and Methods

Patients with or without periodontal disease were included in this cross-sectional study. Subgingival biofilm samples were collected and analyzed by 16S massive pyrosequencing. Functional analyses were also performed.

Results

A total of 15 phyla, 154 genera and 351 species were detected globally. Differences between disease and non-disease samples were observed in all taxonomical levels which suggest functional profile changes in the community. It was found that the main species associated with non-disease samples were reduced in disease but not completely suppressed. Analysis of the functional potential of the biofilms revealed a significantly higher activity related to endocytosis and phosphatidylinositol signaling in the disease group but lower cell adhesion molecules.

Conclusions

Specific differences between health and disease suggest functional profile changes in the community, although bacteria associated with periodontal disease are also increased in health. Transcriptome studies should be conducted to confirm and deepen metabolic dysfunctions.

Key words:Pyrosequencing, 16S rRNA, oral microbiome, periodontitis, functional potential.

Focal Infection and Periodontitis: A Narrative Report and New Possible Approaches

The "focal infection theory" is a historical concept based on the assumption that some infections may cause chronic and acute diseases in different districts of the body. Its great popularity spanned from 1930 to 1950 when, with the aim to remove all the foci of infection, drastic surgical interventions were performed. Periodontitis, a common oral pathology mainly of bacterial origin, is the most evident example of this phenomenon today: in fact, bacteria are able to migrate, develop and cause health problems such as cardiovascular and respiratory diseases, diabetes, and osteoporosis. The aim of this narrative report is to verify the hypothesis of the association between oral infections and systemic diseases by different ways of approach and, at the same time, to propose new kinds of treatment today made possible by technological progress. The analysis of the literature demonstrated a strong relationship between these conditions, which might be explained on the basis of the recent studies on microbiota movement inside the body. Prevention of the oral infections, as well as of the possible systemic implications, may be successfully performed with the help of new technologies, such as probiotics and laser.

Hypothesis: Rheumatoid arthritis and periodontitis: A new possible link via prolactin hormone

Rheumatoid arthritis and periodontitis are two common chronic inflammatory diseases affecting human population worldwide. The association between the two conditions have been the focus of many researches, trying to explore the possible mechanisms underlying this association. Prolactin hormone, besides its known lactogenic effects acts as a cytokine secreted from various tissues other than the pituitary gland with multiple pleotropic actions in immunity and inflammation. Several data showed that prolactin levels are increased significantly in the synovial and periodontal tissues, and this increase is correlated with disease activity and tissue destruction. Our hypothesis suggests that local prolactin can represent a link between the two conditions. In this work, we suggest a possible mechanistic interactions, hypothesized to form a common path linking between rheumatoid arthritis, periodontitis and prolactin. This is because of the need to develop new treatment strategies for the most effective long term control of inflammation in both conditions.

In vivo and ex vivo actions of a novel P. gingivalis inhibitor on multi-species biofilm, inflammatory response, and periodontal bone loss

Chronic periodontitis is one of the most common infectious inflammatory diseases worldwide. Current therapeutic options for the disease are only partially and temporarily successful due to periodontal re-emergence of pathogens such as Porphyromonas gingivalis, a keystone bacterium in the oral microbial communities, which elicits a dysbiosis between the microbiota and the host. Previously, we reported a peptide inhibitor of P. gingivalis (SAPP) that specifically targets P. gingivalis and reduces its virulence potential in vitro. Here, we show that SAPP can modulate the ability of P. gingivalis to suppress the host innate immune system. Using a cytokine array analysis, we found that the levels of several cytokines including IL-6, IL-8, and MCP-1 in the culture media of human oral keratinocytes (HOKs) were significantly diminished in the presence of P. gingivalis. Whereas the levels of these cytokines were restored, at least partially, in the culture media of HOKs by SAPP treatment. Furthermore, we also observed in an ex vivo assay that SAPP efficiently inhibited biofilm primed formation by mixed-species oral bacteria, and significantly dampened the abnormally innate immune responses induced by these bacteria. We also demonstrated, using a mouse model, that SAPP could prevent alveolar bone loss induced by P. gingivalis. Our results suggest that SAPP specifically targets P. gingivalis and its associated bacterial communities and could be envisioned as an emerging therapy for periodontitis.

Glutathione-Stabilized Silver Nanoparticles: Antibacterial Activity against Periodontal Bacteria, and Cytotoxicity and Inflammatory Response in Oral Cells

Silver nanoparticles (AgNPs) have been proposed as new alternatives to limit bacterial dental plaque because of their antimicrobial activity. Novel glutathione-stabilized silver nanoparticles (GSH-AgNPs) have proven powerful antibacterial properties in food manufacturing processes. Therefore, this study aimed to evaluate the potentiality of GSH-AgNPs for the prevention/treatment of oral infectious diseases. First, the antimicrobial activity of GSH-AgNPs against three oral pathogens (Porphyromonas gingivalis, Fusobacterium nucleatum, and Streptococcus mutans) was evaluated. Results demonstrated the efficiency of GSH-AgNPs in inhibiting the growth of all bacteria, especially S. mutans (IC50 = 23.64 μg/mL, Ag concentration). Second, GSH-AgNPs were assayed for their cytotoxicity (i.e., cell viability) toward a human gingival fibroblast cell line (HGF-1), as an oral epithelial model. Results indicated no toxic effects of GSH-AgNPs at low concentrations (≤6.16 µg/mL, Ag concentration). Higher concentrations resulted in losing cell viability, which followed the Ag accumulation in cells. Finally, the inflammatory response in the HGF-1 cells after their exposure to GSH-AgNPs was measured as the production of immune markers (interleukins 6 and 8 (IL-6 and IL-8) and tumor necrosis factor-alpha (TNF-α)). GSH-AgNPs activates the inflammatory response in human gingival fibroblasts, increasing the production of cytokines. These findings provide new insights for the use of GSH-AgNPs in dental care and encourage further studies for their application.

Oral Pathogen Porphyromonas gingivalis Can Escape Phagocytosis of Mammalian Macrophages

Macrophages are phagocytic cells that play a key role in host immune response and clearance of microbial pathogens. Porphyromonas gingivalis is an oral pathogen associated with the development of periodontitis. Escape from macrophage phagocytosis was tested by infecting THP-1-derived human macrophages and RAW 264.7 mouse macrophages with strains of P. gingivalis W83 and 33277 as well as Streptococcus gordonii DL1 and Escherichia coli OP50 at MOI = 100. CFU counts for all intracellular bacteria were determined. Then, infected macrophages were cultured in media without antibiotics to allow for escape and escaping bacteria were quantified by CFU counting. P. gingivalis W83 displayed over 60% of the bacterial escape from the total amount of intracellular CFUs, significantly higher compared to all other bacteria strains. In addition, bacterial escape and re-entry were also tested and P. gingivalis W83, once again, showed the highest numbers of CFUs able to exit and re-enter macrophages. Lastly, the function of the PG0717 gene of P. gingivalis W83 was tested on escape but found not related to this activity. Altogether, our results suggest that P. gingivalis W83 is able to significantly avoid macrophage phagocytosis. We propose this ability is likely linked to the chronic nature of periodontitis.

Respective Effects of Oral Hygiene Instructions and Periodontal Nonsurgical Treatment (Debridement) on Clinical Parameters and Patient-Reported Outcome Measures with Respect to Smoking

BACKGROUND

Oral hygiene instructions (OHI) and periodontal nonsurgical treatment (PNST) play pivotal roles in the management of periodontitis. The study aims to discern their respective effects on periodontal clinical parameters and patient-reported outcome measures (PROMs).

METHODS

Ninety-one patients were included, 34 non-smokers (NS), 25 former smokers (FS) and 32 current smoker (CS). Clinical parameters such as probing depth (PD) and bleeding on probing (BOP) were collected, and the periodontal inflamed tissue area (PISA) was calculated. Clinical parameters and PROMs were recorded before and after receiving OHI, with electronic tooth brush and interdental brushes, as well as 3 months after debridement.

RESULTS

Smokers presented a significantly higher proportion of severe periodontitis (64.7%) with generalized extension (76.5%) and with a rapid rate of progression (97.1%) compared to NS and FS. OHI led to a significant decrease of PD, BOP, and PISA (p < 0.0001) only in NS and FS. Debridement reduced PD and the percentage of PD >6 mm in all groups (p < 0.0001). OHI induced significant improvement of oral hygiene, frequency of interdental cleaning, and PROMs (p < 0.0001). Further debridement induced significant additional improvement PROMs in FS and NS (p < 0.0001).

CONCLUSION

OHI and debridement improved periodontal clinical parameters and PROMs in both NS and FS. Former smokers had comparable outcomes to non-smokers, suggesting that smoking cessation should be encouraged.

Cell-free supernatant of Streptococcus salivarius M18 impairs the pathogenic properties of Pseudomonas aeruginosa and Klebsiella pneumonia

M18 strain of Streptococcus salivarius is a bacterial replacement probiotic that has been suggested for use in the oral cavity. Here, we have shown that S. salivarius M18 cell-free supernatant reduced the growth of the two most common human pathogens Pseudomonas aeruginosa and Klebsiella pneumonia and sensitized the pathogenic bacteria to antibiotic. Besides, the supernatant inhibited biofilm formation of P. aeruginosa drastically. For pinpointing the biomolecular changes that occurred in P. aeruginosa incubated with the probiotic supernatant, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was used. Unsupervised learning algorithms, principal component analysis (PCA) and hierarchical cluster analysis (HCA), and intensity analyses of individual spectral bands exhibited comprehensive alterations in the polysaccharide and lipid contents and compositions of P. aeruginosa cultivated with S. salivarius M18 cell-free supernatant. These results indicate that S. salivarius M18 has the potential for the prevention or alleviation of different pathogen-induced infections along with the infections of oral pathogens.

Antibacterial activity of phellodendron bark against Streptococcus mutans

Streptococcus mutans is a major cause of tooth decay due to its promotion of biofilm formation and acid production. Several plant extracts have been reported to have multiple biological activities such as anti-inflammation and antibacterial effects. This study investigated the antibacterial activity of three plant extracts, phellodendron bark (PB), yucca, and black ginger, and found that PB had a stronger effect than the other extracts. Then, the minimum inhibitory concentration (MIC) of PB against 100 S. mutans strains was investigated. The MIC range of PB was 9.8-312.5 µg/mL. PB suppressed the growth kinetics of S. mutans in a dose-dependent manner, even at sub-MICs of PB. Then, we investigated the effect of PB on S. mutans virulence. The PB suppressed biofilm formation at high concentrations, although PB did not affect the expression of glucosyltransferase genes. Additionally, PB suppressed the decrease in pH from adding an excess of glucose. The expression of genes responsible for acid production was increased by the addition of excess glucose without PB, whereas their expression levels were not increased in the presence of 1× and 2× MIC of PB. Although PB showed a bacteriostatic effect on planktonic S. mutans cells, it was found that more than 2× MIC of PB showed a partial bactericidal effect on biofilm cells. In conclusion, PB not only showed antibacterial activity against S. mutans but also decreased the cariogenic activity in S. mutans.

Effects of Oral Commensal Streptococci on Porphyromonas gingivalis Invasion into Oral Epithelial Cells

The objective of this study was to determine if the interaction between common oral commensal bacteria and oral epithelial cells would provide protective effects against the invasion of periodontopathogen Porphyromonas gingivalis. Oral epithelial OKF6/Tert cells were used in co-cultures with Streptococcus gordonii, Streptococcus oralis, Streptococcus mitis, and Streptococcus intermedius. The viability of OKF6/Tert cells following a bacterial challenge was evaluated by trypan blue exclusion. The adherence of commensal species was determined by CFU counts. P. gingivalis invasion in OKF6/Tert cells was assessed before and after exposure to commensal species according to CFU counts. Viability assays show that only S. gordonii and S. intermedius display low toxicity toward OKF6/Tert cells. Both commensals adhere to OKF6/Tert cells at an average ratio of 1 CFU to 10 cells. P. gingivalis invasion into host cells is significantly reduced by 25% or 60% after exposure to S. gordonii or S. intermedius, respectively. The results suggest that these commensal species bind to host cells and diminish P. gingivalis invasion. This is important in the context of periodontal disease since P. gingivalis primarily acts on the host by invading it. Therefore, efforts to decrease invasion will eventually lead to future therapies harnessing the mechanisms employed by oral commensal bacteria.

Low levels of antibodies for the oral bacterium Tannerella forsythia predict cardiovascular disease mortality in men with myocardial infarction: A prospective cohort study

Antibody levels to periodontal pathogens in prediction of cardiovascular disease (CVD) mortality were explored using data from a health survey in Oslo in 2000 (Oslo II-study) with 12 1/2 years follow-up. IgG antibodies to four common periodontal pathogens; Tannerella forsythia (TF), Porphyromonas gingivalis (PG), and Treponema denticola (TD) all termed collectively the "red complex", and Aggregatibacter actinomycetemcomitans(AA) were analysed. The study sample consisted of 1172 men drawn from a cohort of 6,530 men who participated in the Oslo II-study, where they provided information on medical and dental history. Of the study sample, 548 men had reported prior myocardial infarction (MI) at baseline whereas the remaining 624 men were randomly drawn from the ostensibly healthy participants for comparative analyses. Dental anamnestic information included tooth extractions and oral infections. An inverse relation was found for trend by the quartile risk level of TF predicting CVD mortality, p-value for trend = 0.017. Comparison of the first to fourth quartile of TF antibodies resulted in hazard ratio (HR) = 1.82, 95% confidence interval 1.12-2.94, p = 0.015, adjusted for age, education, diabetes, daily smoking, and systolic blood pressure. Specificity comparing decile 1 to deciles 2-10 of TF predicting mortality was 92.3%. We found an increased HR by low levels of antibodies to the bacterium T. forsythia predicting CVD mortality in a 12 ½ years follow-up in persons who had experienced an MI but not among non-MI men. This novel finding constitutes a plausible causal link between oral infections and CVD mortality.

Dependence of odontogenic abscess on meteorological parameters: truth or myth?

OBJECTIVES

It is still a common belief among dental practitioners that odontogenic abscesses are somehow linked to meteorological parameters. We investigated the influence of different meteorological parameters on the type of surgical abscess treatment (intra- versus extraoral incision) as a measure of the weather-dependent severity of infection.

MATERIALS AND METHODS

In this retrospective cohort study, we analyzed 841 patients who presented at our outpatient clinic with an odontogenic abscess between 2004 and 2013.

RESULTS

We found no statistical dependence between intra- versus extraoral abscess incision with regard to temperature, atmospheric pressure, or relative air humidity. The annual distribution of abscesses was even, and the number of abscesses with greater or lesser mean values of each meteorological parameter did not differ significantly.

CONCLUSIONS

Our results showed no statistical relationship between meteorological parameters and intra- or extraoral abscess incisions.

CLINICAL RELEVANCE

Our analysis supports the assumption that the theorized relationship between odontogenic abscesses and meteorological parameters remains a myth.

Oral health and dental behaviour of patients with left ventricular assist device: a cross-sectional study

Aims

The aim of this cross‐sectional study was the assessment of dental behaviour, oral health, as well as oral health‐related quality of life of patients with left ventricular assist device (LVAD).

Methods and results

Patients (128) with LVAD were recruited from the University Department for Cardiac Surgery at Heart Center, Leipzig, Germany. A healthy control group (HC, n = 113) was included. Dental behaviour was assessed with a standardized questionnaire, and to evaluate oral health‐related quality of life, the German short form of oral health impact profile was applied. The presence of decayed, missing, and filled teeth; dental treatment need; periodontitis severity; and periodontal treatment need were assessed. These findings were correlated to disease‐related and device‐related factors. The minority of patients used aids for interdental hygiene (16.4%). For the LVAD patients, a German short form of oral health impact profile sum score of 4.96 ± 8.67 [0.5; 0–6] was assessed. The LVAD group suffered from more missing teeth (11.91 ± 9.13 vs. 3.70 ± 3.77; P < 0.01) than HC. More severe periodontitis was found in LVAD group (LVAD = 41.4% and HC = 27.4%; P < 0.01). Periodontal treatment need was high in both groups, without a significant difference (LVAD = 84.4% vs. HC = 86.7%; P = 0.71). LVAD therapy as bridge to transplantation was correlated with periodontal treatment need (odds ratio = 11.48 [1.27; 103.86]; P = 0.03). Further correlations between treatment need and disease specific factors were not detected.

Conclusions

Patients with LVAD suffer from a high periodontal treatment need and a lack in oral behaviour. Interdisciplinary special care concepts appear recommendable to improve oral health in LVAD patients.

Microbiome dysbiosis and alcoholic liver disease☆

Microbiome dysbiosis is strongly associated with alcoholic liver disease (ALD). Recent studies on comprehensive analyses of microbiome compositional and functional changes have begun to uncover the mechanistic relation between microbiome and the pathogenesis of ALD. Importantly, targeting the microbiome has become a potential strategy for the prevention and treatment of ALD. In this review, we summarize the clinical evidence of microbiome dysbiosis in ALD patients, and experimental advances in microbiome and metabolomic functional changes in animals with different species and genetic backgrounds in ALD. We also summarize the studies in humanized intestinal microbiome and fecal microbiota transplantation in mice. We introduce new developments in the studies on the role of the circulating bacterial microbiome, oral bacterial microbiome and fungal microbiome in the development of ALD. We highlight the potential mechanisms by which microbiome dysbiosis contributes to ALD, including short chain fatty acid changes, bile acid metabolism, intestinal barrier function, release of bacterial and fungal products, and inflammation. In addition, we summarize the recent developments targeting the microbiome in prevention and treatment of ALD, including dietary nutrient interference, herbal medicine, antibiotics, anti-fungal agents, probiotics, engineered bacterial therapy, fecal transplantation and oral hygiene. Although recent preclinical studies have advanced our understanding of the microbiome and ALD, clinical studies, especially prospective studies with large samples, are needed to better understand the cause-effect of microbiome dysbiosis in ALD. Identifying new precision-based strategies targeting the microbiome are expected to be developed as more effective therapies in ALD.

A review of the influence of periodontal treatment in systemic diseases

The effects and consequences of periodontal diseases might not be confined to the oral cavity. A great body of evidence has arisen supporting the claim demonstrating an association with several systemic conditions and diseases. With different levels of evidence, an association between periodontal disease and cardiovascular disease, diabetes, psoriasis, rheumatoid arthritis, pregnancy outcomes and respiratory diseases has been established. However, the true nature of this association, if it is causal, still remains elusive. For a better understanding of the complex relationships linking different conditions, interventional studies now begin to focus on the possible outcomes of periodontal treatment in relation to the events, symptoms and biomarkers of several systemic disorders, assessing if periodontal treatment has any impact on them, hopefully reducing their severity or prevalence. Therefore, we proceeded to review the recent literature on the subject, attempting to present a brief explanation of the systemic condition or disease, what proposed mechanisms might give biological plausibility to its association with periodontal disease, and finally and more importantly, what data are currently available pertaining to the effects periodontal treatment may have. Raising awareness and discussing the possible benefits of periodontal treatment on overall systemic health is important, in order to change the perception that periodontal diseases are only limited to the oral cavity, and ultimately providing better and comprehensive care to patients.

Insufficient Oral Behaviour and the High Need for Periodontal Treatment in Patients with Heart Insufficiency and after Heart Transplantation: A Need for Special Care Programs?

Background: The aim of this cross-sectional study was the assessment of dental behaviour and oral health condition of heart transplant recipients (HTx) in comparison to patients with heart insufficiency (HI). Methods: Patients attending the Department for Cardiac Surgery, Leipzig Heart Center, Germany were recruited. Standardized questionnaires regarding dental behaviour and periodontal complaints were applied. A dental (decayed-, missing- and filled-teeth index) and periodontal examination (periodontal probing depth (PPD) and clinical attachment loss (CAL)) was performed. Based on the oral findings, dental and periodontal treatment need was determined. Statistics: T-test, Mann-Whitney U test, Chi-square test, and Fisher-test (p < 0.05). Results: A total of 201 patients (HTx: 112, HI: 89) were included. HTx patients were significantly more often allocated to dentists (p < 0.01). Furthermore, the HTx patients rated feeling informed appropriately about oral health more often (p < 0.01). HTx patients used interdental cleaning (p < 0.01) and mouth rinse (p = 0.02) more often than HI patients. No differences between groups were present regarding dental status and periodontitis severity (p > 0.05). Periodontal treatment need was high, showing prevalence of 79.5% (HTx) and 87.6% (HI, p = 0.14), respectively. Conclusions: Both groups show insufficient oral behaviour and a high need for periodontal treatment. Special care programs for HTx candidates and recipients appear recommendable.

Porphyromonas gingivalis Tyrosine Phosphatase Php1 Promotes Community Development and Pathogenicity

Protein-tyrosine phosphorylation in bacteria plays a significant role in multiple cellular functions, including those related to community development and virulence. Metal-dependent protein tyrosine phosphatases that belong to the polymerase and histindinol phosphatase (PHP) family are widespread in Gram-positive bacteria. Here, we show that Porphyromonas gingivalis, a Gram-negative periodontal pathogen, expresses a PHP protein, Php1, with divalent metal ion-dependent tyrosine phosphatase activity. Php1 tyrosine phosphatase activity was attenuated by mutation of conserved histidine residues that are important for the coordination of metal ions and by mutation of a conserved arginine residue, a key residue for catalysis in other bacterial PHPs. The php1 gene is located immediately downstream of the gene encoding the bacterial tyrosine (BY) kinase Ptk1, which was a substrate for Php1 in vitro Php1 rapidly caused the conversion of Ptk1 to a state of low tyrosine phosphorylation in the absence of discernible intermediate phosphoforms. Active Php1 was required for P. gingivalis exopolysaccharide production and for community development with the antecedent oral biofilm constituent Streptococcus gordonii under nutrient-depleted conditions. In contrast, the absence of Php1 had no effect on the ability of P. gingivalis to form monospecies biofilms. In vitro, Php1 enzymatic activity was resistant to the effects of the streptococcal secreted metabolites pABA and H2O2, which inhibited Ltp1, an enzyme in the low-molecular-weight (LMW) phosphotyrosine phosphatase family. Ptk1 reciprocally phosphorylated Php1 on tyrosine residues 159 and 161, which independently impacted phosphatase activity. Loss of Php1 rendered P. gingivalis nonvirulent in an animal model of periodontal disease. Collectively, these results demonstrate that P. gingivalis possesses active PHP and LMW tyrosine phosphatases, a unique configuration in Gram-negatives which may allow P. gingivalis to maintain phosphorylation/dephosphorylation homeostasis in multispecies communities. Moreover, Php1 contributes to the pathogenic potential of the organism.IMPORTANCE Periodontal diseases are among the most common infections of humans and are also associated with systemic inflammatory conditions. Colonization and pathogenicity of P. gingivalis are regulated by signal transduction pathways based on protein tyrosine phosphorylation and dephosphorylation. Here, we identify and characterize a novel component of the tyrosine (de)phosphorylation axis: a polymerase and histindinol phosphatase (PHP) family enzyme. This tyrosine phosphatase, designated Php1, was required for P. gingivalis community development with other oral bacteria, and in the absence of Php1 activity P. gingivalis was unable to cause disease in a mouse model of periodontitis. This work provides significant insights into the protein tyrosine (de)phosphorylation network in P. gingivalis, its adaptation to heterotypic communities, and its contribution to colonization and virulence.

Antibacterial activity of disodium succinoyl glycyrrhetinate, a derivative of glycyrrhetinic acid against Streptococcus mutans

Streptococcus mutans is a cariogenic bacterium that localizes in the oral cavity. Glycyrrhetinic acid (GRA) is a major component of licorice extract. GRA and several derivatives, including disodium succinoyl glycyrrhetinate (GR-SU), are known to have anti-inflammatory effects in humans. In this study, the antimicrobial effect of GRA and its derivatives against the S. mutans UA159 strain were investigated. Minimum inhibitory concentrations (MICs) of GRA and GR-SU showed antibacterial activity against the S. mutans strain, whereas other tested derivatives did not. Because GR-SU is more soluble than GRA, GR-SU was used for further experiments. The antibacterial activity of GR-SU against 100 S. mutans strains was evaluated and it was found that all strains are susceptible to GR-SU, with MIC values below 256 µg/mL. A cell viability assay showed that GR-SU has a bacteriostatic effect on S. mutans cells. As to growth kinetics, sub-MICs of GR-SU inhibited growth. The effect of GR-SU on S. mutans virulence was then investigated. GR-SU at sub-MICs suppresses biofilm formation. Additionally, GR-SU greatly suppresses the pH drop caused by the addition of glucose and glucose-induced expression of the genes responsible for acid production (ldh and pykF) and tolerance (aguD and atpD). Additionally, expression of enolase, which is responsible for the carbohydrate phosphotransferase system, was not increased in the presence of GR-SU, indicating that GR-SU suppresses incorporation of sugars into S. mutans. In conclusion, GR-SU has antibacterial activity against S. mutans and also decreases S. mutans virulence.

Low-grade inflammation causes gap junction-coupled cell dysfunction throughout the body, which can lead to the spread of systemic inflammation

BACKGROUND AND AIMS

Gap junction-coupled cells form networks in different organs in the body. These networks can be affected by inflammatory stimuli and become dysregulated. Cell signaling is also changed through connexin-linked gap junctions. This alteration affects the surrounding cells and extracellular matrix in organs. These changes can cause the spread of inflammatory substances, thus affecting other network-linked cells in other organs in the body, which can give rise to systemic inflammation, which in turn can lead to pain that can turn into chronic.

METHODS

This is a review based on literature search and our own research data of inflammatory stimuli that can affect different organs and particularly gap-junction-coupled cells throughout the body.

CONCLUSIONS

A remaining question is which cell type or tissue is first affected by inflammatory stimuli. Can endotoxin exposure through the air, water and body start the process and are mast cells the first target cells that have the capacity to alter the physiological status of gap junction-coupled cells, thereby causing breakdown of different barrier systems?

IMPLICATIONS

Is it possible to address the right cellular and biochemical parameters and restore inflammatory systems to a normal physiological level by therapeutic strategies?

Amino acids as wetting agents: surface translocation by Porphyromonas gingivalis

Our understanding of how oral microbiota adapt in response to changes in their surroundings remains limited. This is particularly true of the slow-growing anaerobes that persist below the gum line. Here, we report that the oral anaerobe Porphyromonas gingivalis strain 381 can surface translocate when sandwiched between two surfaces. We show that during movement, this bacterium alters its metabolism, specifically side products of arginine utilization including citrulline and ornithine accumulated in the translocating cells; while arginine, N-acetyl-arginine, and the polyamine putrescine, which is produced from arginine were consumed. In addition, our results indicate that movement requires modification of the surrounding environment via proteolysis, cell dispersion, cell-on-cell rolling, and sub-diffusive cell-driven motility. We also show that production of fimbriae and fimbriae-associated proteins; as well as the regulation of contact-dependent growth inhibition genes, which are known to be involved in self-nonself discrimination, and the type IX secretion system are central to surface translocation. These studies provide a first glimpse into P. gingivalis motility and its relationship to ecological variables.

Salivary Microbial Dysbiosis is Associated with Systemic Inflammatory Markers and Predicted Oral Metabolites in Non-Small Cell Lung Cancer Patients

An increasing number of studies have suggested the dysbiosis of salivary microbiome has been linked to the advancement of multiple diseases and proved to be helpful for the diagnosis of them. Although epidemiological studies of salivary microbiota in carcinogenesis are mounting, no systemic study exists regarding the oral microbiota of non-small cell lung cancer (NSCLC) patients. In this study, we presented the characteristics of the salivary microbiota in patients from NSCLC and healthy controls by sequencing of the 16S rRNA microbial genes. Our result revealed distinct salivary microbiota composition in patients from NSCLC compared to the healthy controls. As principal co-ordinates analysis (PCoA) showed, saliva samples clearly differed between the two groups, considering the weighted (p = 0.001, R² = 0.17), and unweighted (p = 0.001, R² = 0.25) UniFrac distance. Phylum Firmicutes (31.69% vs 24.25%, p < 0.05) and its two genera Veillonella (15.51%% vs 9.35%, p < 0.05) and Streptococcus (9.96% vs 6.83%, p < 0.05) were strongly increased in NSCLC group compared to the controls. Additionally, the relative abundances of Fusobacterium (3.06% vs 4.92%, p = 0.08), Prevotella (1.45% vs 3.52%, p < 0.001), Bacteroides (0.56% vs 2.24%, p < 0.001), and Faecalibacterium (0.21% vs 1.00%, p < 0.001) in NSCLC group were generally decreased. Furthermore, we investigated the correlations between systemic inflammation markers and salivary microbiota. Neutrophil-lymphocyte ratio (NLR) positively correlated with the Veillonella (r =0.350, p = 0.007) and lymphocyte-monocyte ratio (LMR) negatively correlated with Streptococcus (r =-0.340, p = 0.008). Additionally, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways inferred by phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) showed that pathways related to xenobiotics biodegradation and metabolism (p < 0.05) and amino acid metabolism (p < 0.05) were enriched in the NSCLC group. Folate biosynthesis (p < 0.05) significantly decreased in NSCLC group. The specific correlations of clinical systemic inflammation markers and predicted KEGG pathways also could pronounce a broad understanding of salivary microbiota in patients with NSCLC. Moreover, our study extended the new sight into salivary microbiota-targeted interventions to clinically improve the therapeutic strategies for salivary dysbiosis in NSCLC patients. Further investigations of the potential mechanism of salivary microbiota in the progression of NSCLC are still in demand.

Comparative Analysis of Gene Expression Patterns for Oral Epithelium-Related Functions with Aging

Epithelial cells and functions of the epithelium are critical to the health of the oral cavity. We used a nonhuman primate model to profile the transcriptome of gingival tissues in health across the lifespan and hypothesized that in older animals, epithelial-related transcriptome patterns would reflect epithelial cells that are aggressively responsive to the surrounding environment and less able to modulate and resolve the noxious challenge from the bacteria. Rhesus monkeys (n = 34) with a healthy periodontium were distributed into four groups: ≤3 years (young), 3-7 years (adolescent), 12-16 years (adult), and 18-23 years (aged), and a buccal gingival sample from the premolar/molar region of each animal was obtained. RNA was subjected to a microarray analysis (GeneChip^® Rhesus Macaque Genome Array, Affymetrix), and 336 genes examined that are linked to epithelium and epithelial cell functions categorized into 9 broad functional groups: extracellular matrix and cell structure; extracellular matrix remodeling enzymes; cell adhesion molecules, cytoskeleton regulation; inflammatory response; growth factors; kinases/cell signaling; cell surface receptors; junction associated molecules; autophagy/apoptosis; antimicrobial peptides; and transcription factors. Total of 255 genes displayed a normalized signal >100, and differences across the age groups were observed primarily in extracellular matrix and cell structure, cell adhesion molecules, and cell surface receptor gene categories with elevations in the aged tissues. Keratins 2, 5, 6B, 13, 16, 17 were all significantly increased in healthy-aged tissues versus adults, and keratins 1 and 2 were significantly decreased in young animals. Approximately 15 integrins are highly expressed in the gingival tissues across the age groups with only ITGA8, ITGAM (CD11b), and ITGB2 significantly increased in the aged tissues. Little impact of aging on desmosomal/hemidesmosomal genes was noted. These results suggest that healthy gingival aging has a relatively limited impact on the broader functions of the epithelium and epithelial cells, with some effects on genes for extracellular matrix and cell adhesion molecules (e.g., integrins). Thus, while there is a substantial impact of aging on immune system targets even in healthy gingiva, it appears that the epithelial barrier remains reasonably molecularly intact in this model system.

The oral microbiota: dynamic communities and host interactions

The dynamic and polymicrobial oral microbiome is a direct precursor of diseases such as dental caries and periodontitis, two of the most prevalent microbially induced disorders worldwide. Distinct microenvironments at oral barriers harbour unique microbial communities, which are regulated through sophisticated signalling systems and by host and environmental factors. The collective function of microbial communities is a major driver of homeostasis or dysbiosis and ultimately health or disease. Despite different aetiologies, periodontitis and caries are each driven by a feedforward loop between the microbiota and host factors (inflammation and dietary sugars, respectively) that favours the emergence and persistence of dysbiosis. In this Review, we discuss current knowledge and emerging mechanisms governing oral polymicrobial synergy and dysbiosis that have both enhanced our understanding of pathogenic mechanisms and aided the design of innovative therapeutic approaches for oral diseases.