Salivary microbiota in periodontal health and disease and their changes following nonsurgical periodontal treatment

Salivary microbiota reflecting changes in subgingival microbiota

The purpose of this study was to determine whether subgingival microbial changes according to the severity of periodontal disease and following the non-surgical periodontal treatment of periodontitis are reflected in the saliva microbiota. Subgingival and saliva samples were collected from 7 periodontally healthy controls, 14 patients with gingivitis, 12 with moderate periodontitis, and 18 with severe periodontitis. Among subjects who received treatment, seven moderate and seven severe periodontitis patients were selected for post-treatment microbial analysis, and their samples were analyzed at baseline and 6 months after treatment. The V3 and V4 regions of the 16S rRNA gene were sequenced, and correlations of the relative abundance of phyla and health- or periodontitis-dominant species between subgingival plaque and saliva samples were analyzed using Spearman signed-rank tests. Alpha diversity was higher in saliva than subgingival plaque samples, and beta diversity was significantly different between the two samples. However, levels of phyla and most health- or periodontitis-dominant species in salivary microbiota were significantly correlated with those in subgingival plaque. The improvement in clinical parameters following treatment was accompanied by a microbial shift not only in subgingival plaque but also in saliva. The abundance of 2 phyla including Bacteroidetes, 6 genera including Porphyromonas and Treponema, and 11 species including Porphyromonas gingivalis, Tannerella forsythia, and Filifactor alocis was significantly reduced in saliva following treatment. These results indicate that the salivary microbiota can reflect changes in the subgingival microbiota, suggesting that saliva can be used as a diagnostic tool to monitor the periodontal health status of individuals.

IMPORTANCE

The salivary microbiota has attracted increasing attention as a promising method for monitoring periodontal disease. With regard to the pathogenesis of periodontal disease, however, subgingival plaque microbiota is the dominant etiological factor. Although it has been established that periodontopathogenic bacteria exist in saliva and their distribution differs, depending on the severity of the disease, it is necessary to analyze the extent to which the salivary microbiota reflects the subgingival microbiota. This study explored whether subgingival microbial changes according to the severity of periodontal disease and following the non-surgical periodontal treatment of periodontitis are reflected in the saliva microbiota and concluded that the salivary microbiota can reflect changes in the subgingival microbiota. Saliva can be used as a diagnostic tool to monitor the periodontal health status of individuals.

Association of Fusobacterium nucleatum in human saliva with periodontal status and composition of the salivary microbiome including periodontopathogens

Fusobacterium nucleatum promotes dental biofilm formation, increases the prevalence of periodontal disease, and is associated with systemic diseases such as colorectal cancer. However, differences in the composition of salivary microbiome among groups based on the abundance of F. nucleatum are unclear. Therefore, we analyzed the difference in salivary microbiome among groups based on the abundance of F. nucleatum in saliva samples collected from 611 subjects in Japan. Salivary DNA was extracted, and the oral microbiome was analyzed using next-generation sequencing of 16S rRNA. The relationship between F. nucleatum and the community periodontal index was evaluated to examine effects on periodontal status, and α- and β-diversity were analyzed in four groups based on quantiles of relative abundance of F. nucleatum. Spearman rank correlation tests were used to examine relationships between the relative abundance of F. nucleatum and oral bacteria. Subjects with the highest quantiles of F. nucleatum had a higher prevalence of periodontitis compared with those with the lowest quantile. β-Diversity also differed among these four groups. F. nucleatum showed significant correlations with several periodontopathogens, including the red complex, Prevotella intermedia, Filifactor alocis, and Fretibacterium ssp. These results suggest that the relative abundance of F. nucleatum in saliva is associated with periodontal status and the composition of the salivary microbiome, including the red complex and periodontopathogens.

IMPORTANCE

We characterized the composition of the saliva microbiome in groups based on the abundance of Fusobacterium nucleatum. There is a lot of periodontitis in subjects with a high abundance of F. nucleatum. The diversity of the saliva microbiome was different among groups based on the abundance of F. nucleatum. The abundance of F. nucleatum correlated with various periodontopathogens including red complex. These results support the influence of the abundance of F. nucleatum in saliva on periodontal status and the composition of the salivary microbiome, including the red complex and periodontopathogens.

Saliva assay: a call for methodological standardization

The oral cavity provides an ideal environment for microorganisms, including bacteria, viruses, and fungi, to flourish. Increasing attention has been focused on the connection between the oral microbiome and both oral and systemic diseases, spurring active research into the collection and analysis of specimens for healthcare purposes. Among the various methods for analyzing the oral microbiome, saliva analysis is especially prominent. Saliva samples, which can be collected non-invasively, provide information on the systemic health and oral microbiome composition of an individual. This review was performed to evaluate the current state of the relevant research through an examination of the literature and to suggest an appropriate assay method for investigating the oral microbiome. We analyzed articles published in English in SCI(E) journals after January 1, 2000, ultimately selecting 53 articles for review. Articles were identified through keyword searches in the PubMed, Embase, Cochrane, Web of Science, and CINAHL databases. Three experienced researchers conducted full-text assessments following title and abstract screening to select appropriate papers. Subsequently, they organized and analyzed the desired data. Our review revealed that most studies utilized unstimulated saliva samples for oral microbiome analysis. Of the 53 studies examined, 29 identified relationships between the oral microbiome and various diseases, such as oral disease, Behçet disease, cancer, and oral lichen planus. However, the studies employed diverse methods of collection and analysis, which compromised the reliability and accuracy of the findings. To address the limitations caused by methodological inconsistencies, a standardized saliva assay should be established.

Association of F. alocis and D. pneumosintes with Periodontitis Disease Severity and Red Complex Bacteria

Oral biofilms are considered the principal etiological agent in the development of periodontitis. Novel species that may contribute to periodontitis and dysbiosis have been identified recently. The study aims to evaluate the presence of F. alocis and D. pneumosintes in healthy and diseased patients and their association with clinical parameters and with red complex bacteria. The study included 60 subjects, with 30 patients each in the healthy and periodontitis groups. The clinical parameters were noted, and samples were subjected to DNA extraction followed by a polymerase chain reaction. Statistical analysis was performed using the Graph Pad Prism software. Results: F. alocis and D. pneumosintes were detected at a significantly higher percentage in the periodontitis group compared to the healthy group (p < 0.05). D. pneumosintes was significantly associated with T. forsythia in the periodontitis group (p < 0.05). Both of these organisms were present in sites with higher clinical attachment loss (p < 0.05). This study demonstrated that both F. alocis and D. pneumosintes were detected at a significantly higher percentage in periodontitis subjects and were detected more frequently in sites with a greater clinical attachment loss. It was also evident that both F. alocis and D. pneumosintes can be present independently of other putative periodontal pathogens.

Decreased GCF DEL-1 and increased GCF neutrophils with increasing probing pocket depth

PURPOSE

Developmental endothelial locus-1 (DEL-1) plays a role in regulating neutrophil migration within the periodontium. The objective of this study was to evaluate the levels of DEL-1 in saliva and gingival crevicular fluid (GCF), as well as the number of neutrophils in patients with periodontitis.

METHODS

Forty systemically healthy, non-smoking periodontitis patients participated in this study. Clinical periodontal parameters, including the plaque index, probing pocket depth (PPD), clinical attachment level, bleeding on probing, modified sulcular bleeding index, and marginal bone level, were measured. Levels of DEL-1, interleukin (IL)-1β, IL-6, and IL-8 in unstimulated saliva samples, as well as DEL-1 in the GCF of 3 teeth from each participant, were assessed. Neutrophil counts in oral rinse and GCF samples were recorded. Spearman correlation coefficients were used to examine the correlation between protein levels, clinical parameters, and neutrophil quantities. Participants were divided into 2 age groups (those under 50 years and those 50 years or older) in order to investigate potential age-related differences.

RESULTS

DEL-1 levels in the GCF showed a negative relationship with PPD (sum). Neutrophils in oral rinse samples were positively correlated with PPD, IL-8, and IL-1β levels. Neutrophils in GCF exhibited a positive correlation with PPD (sum). Salivary DEL-1 levels showed correlations with IL-8 and IL-1β, but not with the clinical parameters of periodontitis.

CONCLUSIONS

The negative relationship observed between PPD and GCF DEL-1 levels is consistent with the proposed protective role of DEL-1.

A rapid and sensitive CRISPR-Cas12a for the detection of Fusobacterium nucleatum

Fusobacterium nucleatum (Fn), as a conditional pathogen, can cause a range of oral and gastrointestinal diseases. However, existing clinical detection methods require expensive equipment and complex procedures, which are inconvenient for large-scale screening in epidemiological research. The purpose of this study was to establish a reliable, rapid, and inexpensive detection method based on CRISPR/Cas12a technology for the detection of Fn. Specific recombinase polymerase amplification (RPA) primer sequences and crRNA sequences were designed based on the nusG gene of Fn. Subsequently, a fluorescence assay and a lateral flow immunoassay were established using the RPA and CRISPR-Cas12a system (RPA-CRISPR-Cas12a). Sensitivity validation revealed a limit of detection of 5 copies/µL. This method could distinguish Fn from other pathogens with excellent specificity. Furthermore, the RPA-CRISPR-Cas12a assay was highly consistent with the classical quantitative real-time PCR method when testing periodontal pocket samples. This makes it a promising method for the detection of Fn and has the potential to play an increasingly important role in infectious disease testing.IMPORTANCEFusobacterium nucleatum (Fn) naturally exists in the microbial communities of the oral and gastrointestinal tracts of healthy individuals and can cause inflammatory diseases in the oral and gastrointestinal tracts. Recent studies have shown that Fn is closely associated with the occurrence and development of gastrointestinal cancer. Therefore, the detection of Fn is very important. Unlike the existing clinical detection methods, this study established a fluorescence-based assay and lateral flow immunoassay based on the RPA and CRISPR-Cas12a system (RPA-CRISPR-Cas12a), which is fast, reliable, and inexpensive and can complete the detection within 30-40 minutes. This makes it a promising method for the detection of Fn and has the potential to play an increasingly important role in infectious disease testing.

Causal relationship between PCOS and related sex hormones with oral inflammatory diseases: a bidirectional Mendelian randomization study

Background

Observational studies have identified a strong association between polycystic ovary syndrome (PCOS) and hormone levels related to oral inflammatory diseases. To better understand the relationship between them, we conducted an analysis using a two-sample Mendelian randomization (MR) approach.

Methods

We gathered summary statistical data from previously published genome-wide association studies (GWAS) on PCOS and three sex hormones (AMH, Estradiol, LH) along with four oral inflammatory diseases (painful gums, loose teeth, mouth ulcers, and toothache). We selected single nucleotide polymorphisms (SNPs) as instrumental variables and employed four types of MR analysis methods to evaluate causal relationships between exposure and outcome. Finally, the robustness of our results was further validated through sensitivity tests and reverse MR.

Results

We observed that PCOS could increase the risk of mouth ulcers (ORIVW= 1.0013, 95%CI: 1.0001-1.0025, PIVW = 0.0278), painful gums (ORIVW= 1.0015, 95%CI:1.0003-1.0027, PIVW = 0.0163), and loose teeth (ORIVW= 1.0014, 95%CI: 1.0001-1.0027, PIVW = 0.0328). Moreover, LH was also found to increase the risk of mouth ulcers (ORIVW= 1.0031, 95%CI: 0.0001-1.0062, PIVW = 0.0457). MR-Egger regression, weighted mode, and WE indicated similar results. Additionally, we discovered no causal link between PCOS and toothache (PIVW>0.05), LH and painful gums, loose teeth, or toothache (PIVW>0.05), or AMH and Estradiol level with any of the four oral diseases (PIVW>0.05).

Conclusion

Our research provides new insights and references for exploring the effects of PCOS and related hormones on oral inflammatory lesions. For patients with PCOS, especially those with elevated LH levels, early intervention measures should be taken to prevent the occurrence of oral inflammatory diseases.

A pulmonary abscess caused by Porphyromonas endodontalis infection:A case report and literature review

Porphyromonas endodontalis is an oral anaerobic bacterium associated with periodontitis but seldomly been detected in other diseases. Only one case of respiratory disease caused by Porphyromonas endodontalis, pyopneumothorax, has been reported so far. A 53-year-old man with refractory periodontitis was admitted due to an indeterminate lung space-occupying lesion. Following mNGS analysis of the liquefaction necrotic area and solid component of the lesion through biopsy, Porphyromonas endodontalis and Parvimonas micra were detected. Therefore, the patient was diagnosed with an aspiration lung abscess and discharged after receiving effective antibacterial treatment. The Chest computed tomography (CT) scan revealed a remarkable improvement during outpatient follow-up. In this study, we applied mNGS to diagnose a case of lung abscess attributed to an uncommon bacterium successfully, suggesting that when patients complicated with periodontal diseases and clinical respiratory symptoms, the possibility of inhalation disease caused by oral pathogens should be considered.

Periodontitis and atherosclerotic cardiovascular disease: A critical appraisal

In spite of intensive research efforts driving spectacular advances in terms of prevention and treatments, cardiovascular diseases (CVDs) remain a leading health burden, accounting for 32% of all deaths (World Health Organization. "Cardiovascular Diseases (CVDs)." WHO, February 1, 2017, https://www.who.int/news-room/fact-sheets/detail/cardiovascular-diseases-(cvds)). Cardiovascular diseases are a group of disorders affecting the heart and blood vessels. They encompass a collection of different conditions, among which atherosclerotic cardiovascular disease (ASCVD) is the most prevalent. CVDs caused by atherosclerosis, that is, ASCVD, are particularly fatal: with heart attack and stroke being together the most prevalent cause of death in the world. To reduce the health burden represented by ASCVD, it is urgent to identify the nature of the "residual risk," beyond the established risk factors (e.g., hypertension) and behavioral factors already maximally targeted by drugs and public health campaigns. Remarkably, periodontitis is increasingly recognized as an independent cardiovascular risk factor.

Salivary microbiome of healthy women of reproductive age

IMPORTANCE

The salivary microbiome has been proven to play a crucial role in local and systemic diseases. Moreover, the effects of biological and lifestyle factors such as oral hygiene and smoking on this microbial community have already been explored. However, what was not yet well understood was the natural variation of the saliva microbiome in healthy women and how this is associated with specific use of hormonal contraception and with the number of different sexual partners with whom microbiome exchange is expected regularly. In this paper, we characterized the salivary microbiome of 255 healthy women of reproductive age using an in-depth questionnaire and self-sampling kits. Using the large metadata set, we were able to investigate the associations of several host-related and lifestyle variables with the salivary microbiome profiles. Our study shows a high preservation between individuals.

Characteristics of the Salivary Microbiota in Periodontal Diseases and Potential Roles of Individual Bacterial Species To Predict the Severity of Periodontal Disease

The purposes of this study were to examine the compositional changes in the salivary microbiota according to the severity of periodontal disease and to verify whether the distribution of specific bacterial species in saliva can distinguish the severity of disease. Saliva samples were collected from 8 periodontally healthy controls, 16 patients with gingivitis, 19 patients with moderate periodontitis, and 29 patients with severe periodontitis. The V3 and V4 regions of the 16S rRNA gene in the samples were sequenced, and the levels of 9 bacterial species showing significant differences among the groups by sequencing analysis were identified using quantitative real-time PCR (qPCR). The predictive performance of each bacterial species in distinguishing the severity of disease was evaluated using a receiver operating characteristic curve. Twenty-nine species, including Porphyromonas gingivalis, increased as the severity of disease increased, whereas 6 species, including Rothia denticola, decreased. The relative abundances of P. gingivalis, Tannerella forsythia, Filifactor alocis, and Prevotella intermedia determined by qPCR were significantly different among the groups. The three bacterial species P. gingivalis, T. forsythia, and F. alocis were positively correlated with the sum of the full-mouth probing depth and were moderately accurate at distinguishing the severity of periodontal disease. In conclusion, the salivary microbiota showed gradual compositional changes according to the severity of periodontitis, and the levels of P. gingivalis, T. forsythia, and F. alocis in mouth rinse saliva had the ability to distinguish the severity of periodontal disease. IMPORTANCE Periodontal disease is one of the most widespread medical conditions and the leading cause of tooth loss, imposing high economic costs and an increasing burden worldwide as life expectancy increases. Changes in the subgingival bacterial community during the progression of periodontal disease can affect the entire oral ecosystem, and bacteria in saliva can reflect the degree of bacterial imbalance in the oral cavity. This study explored whether the specific bacterial species in saliva can distinguish the severity of periodontal disease by analyzing the salivary microbiota and suggested P. gingivalis, T. forsythia, and F. alocis as biomarkers for distinguishing the severity of periodontal disease in saliva.

Characterization of the salivary microbiome before and after antibiotic therapy via separation technique

In the present research, the MALDI-TOF MS technique was applied as a tool to rapidly identify the salivary microbiome. In this fact, it has been monitored the changes occurred in molecular profiles under different antibiotic therapy. Significant changes in the composition of the salivary microbiota were noticed not only in relation to the non antibiotic (non-AT) and antibiotic treatment (AT) groups, but also to the used media, the antibiotic therapy and co-existed microbiota. Each antibiotic generates specific changes in molecular profiles. The highest number of bacterial species was isolated in the universal culture medium (72%) followed by the selective medium (48% and 38%). In the case of non-AT patients, the prevalence of Streptococcus salivarius (25%), Streptococcus vestibularis (19%), Streptococcus oralis (13%), and Staphylococcus aureus (6%) was identified while in the case of AT, Streptococcus salivarius (11%), Streptococcus parasanguinis (11%), Staphylococcus epidermidis (12%), Enterococcus faecalis (9%), Staphylococcus hominis (8%), and Candida albicans (6%) were identified. Notable to specified that the Candida albicans was noticed only in AT samples, indicating a negative impact on the antibiotic therapy. The accuracy of the MALDI-TOF MS technique was performed by the 16S rRNA gene sequencing analysis-as a reference method. Conclusively, such an approach highlighted in the present study can help in developing the methods enabling a faster diagnosis of disease changes at the cellular level before clinical changes occur. Once the MALDI tool allows for the distinguishing of the microbiota of non-AT and AT, it may enable to monitor the diseases treatment and develop a treatment regimen for individual patients in relation to each antibiotic. KEY POINTS: The salivary microbiota of antibiotic-treated patients was more bacteria variety MALDI-TOF MS is a promising tool for recording of reproducible molecular profiles Our data can allow to monitor the treatment of bacterial diseases for patients.

High-Throughput Sequencing Analysis of the Changes in the Salivary Microbiota of Hungarian Young and Adult Subpopulation by an Anthocyanin Chewing Gum and Toothbrush Change

The sour cherry contains anthocyanins, which have bactericide action against some oral bacteria (Klebsiella pneumoniae, Pseudomonas aeruginosa). Sour cherry also has antibiofilm action against Streptococcus mutans, Candida albicans, and Fusobacterium nucleatum. Our earlier research proved that chewing sour cherry anthocyanin gum significantly reduces the amount of human salivary alpha-amylase and Streptococcus mutans levels. The microbiota of a toothbrush affects oral health and regular toothbrush change is recommended. A total of 20 healthy participants were selected for the study. We analysed saliva samples with 16S rRNA sequencing to investigate the effect of 2 weeks (daily three times, after main meals) of chewing sour cherry anthocyanin gum-supplemented by toothbrush change in half of our case-control study cohort-after scaling on human oral microbiota. A more stable and diverse microbiome could be observed after scaling by the anthocyanin gum. Significant differences between groups (NBR: not toothbrush changing; BR: toothbrush changing) were evaluated by log₂ proportion analysis of the most abundant family and genera. The analysis showed that lower level of some Gram-negative anaerobic (Prevotella melaninogenica, Porphyromonas pasteri, Fusobacterium nucleatum subsp. vincentii) and Gram-positive (Rothia mucilaginosa) bacteria could be observed in the case group (BR), accompanied by build-up of health-associated Streptococcal network connections.

Bidirectional association between polycystic ovary syndrome and periodontal diseases

Polycystic ovary syndrome (PCOS) and periodontal disease (PDD) share common risk factors. The bidirectional interaction between PCOS and PDD has been reported, but until now, the underlying molecular mechanisms remain unclear. Endocrine disorders including hyperandrogenism (HA) and insulin resistance (IR) in PCOS disturb the oral microbial composition and increase the abundance of periodontal pathogens. Additionally, PCOS has a detrimental effect on the periodontal supportive tissues, including gingiva, periodontal ligament, and alveolar bone. Systemic low-grade inflammation status, especially obesity, persistent immune imbalance, and oxidative stress induced by PCOS exacerbate the progression of PDD. Simultaneously, PDD might increase the risk of PCOS through disturbing the gut microbiota composition and inducing low-grade inflammation and oxidative stress. In addition, genetic or epigenetic predisposition and lower socioeconomic status are the common risk factors for both diseases. In this review, we will present the latest evidence of the bidirectional association between PCOS and PDD from epidemiological, mechanistic, and interventional studies. A deep understanding on their bidirectional association will be beneficial to provide novel strategies for the treatment of PCOS and PDD.

Tobacco smoke exacerbates Filifactor alocis pathogenicity

AIM

Filifactor alocis has recently emerged as a periodontal pathobiont that appears to thrive in the oral cavity of smokers. We hypothesized that identification of smoke-responsive F. alocis genes would provide insight into adaptive strategies and that cigarette smoke would enhance F. alocis pathogenesis in vivo.

MATERIALS AND METHODS

F. alocis was grown in vitro and cigarette smoke extract-responsive genes determined by RNAseq. Mice were exposed, or not, to mainstream 1R6F research cigarette smoke and infected with F. alocis, or not, in an acute ligature model of periodontitis. Key clinical, infectious, and immune data were collected.

RESULTS

In culture, F. alocis growth was unaffected by smoke conditioning and only a small number of genes were specifically regulated by smoke exposure. Reduced murine mass, differences in F. alocis-cognizant antibody production, and altered immune profiles as well as altered alveolar bone loss were all attributable to smoke exposure and/or F. alocis infection in vivo.

CONCLUSIONS

F. alocis is well-adapted to tobacco-rich conditions and its pathogenesis is enhanced by tobacco smoke exposure. A smoke-exposed ligature model of periodontitis shows promise as a tool with which to further unravel mechanisms underlying tobacco-enhanced, bacteria-induced disease.

Association of general health and lifestyle factors with the salivary microbiota - Lessons learned from the ADDITION-PRO cohort

INTRODUCTION

Previous research indicates that the salivary microbiota may be a biomarker of oral as well as systemic disease. However, clarifying the potential bias from general health status and lifestyle-associated factors is a prerequisite of using the salivary microbiota for screening.

MATERIALS & METHODS

ADDDITION-PRO is a nationwide Danish cohort, nested within the Danish arm of the Anglo-Danish-Dutch Study of Intensive treatment in People with Screen-Detected Diabetes in Primary Care. Saliva samples from n=746 individuals from the ADDITION-PRO cohort were characterized using 16s rRNA sequencing. Alpha- and beta diversity as well as relative abundance of genera was examined in relation to general health and lifestyle-associated variables. Permutational multivariate analysis of variance (PERMANOVA) was performed on individual variables and all variables together. Classification models were created using sparse partial-least squares discriminant analysis (sPLSDA) for variables that showed statistically significant differences based on PERMANOVA analysis (p < 0.05).

RESULTS

Glycemic status, hemoglobin-A_1c (HbA_1c) level, sex, smoking and weekly alcohol intake were found to be significantly associated with salivary microbial composition (individual variables PERMANOVA, p < 0.05). Collectively, these variables were associated with approximately 5.8% of the observed differences in the composition of the salivary microbiota. Smoking status was associated with 3.3% of observed difference, and smoking could be detected with good accuracy based on salivary microbial composition (AUC 0.95, correct classification rate 79.6%).

CONCLUSIONS

Glycemic status, HbA_1c level, sex, smoking and weekly alcohol intake were significantly associated with the composition of the salivary microbiota. Despite smoking only being associated with 3.3% of the difference in overall salivary microbial composition, it was possible to create a model for detection of smoking status with a high correct classification rate. However, the lack of information on the oral health status of participants serves as a limitation in the present study. Further studies in other cohorts are needed to validate the external validity of these findings.

Short-term head-down bed rest microgravity simulation alters salivary microbiome in young healthy men

Microgravity influences are prevalent during orbital flight and can adversely affect astronaut physiology. Notably, it may affect the physicochemical properties of saliva and the salivary microbial community. Therefore, this study simulates microgravity in space using a ground-based -6° head-down bed rest (HDBR) test to observe the effects of microgravity on oral salivary secretion function and the salivary microbiome. Sixteen healthy young male volunteers were recruited for the 15-day -6° HDBR test. Non-stimulated whole saliva was collected on day 1 (pre-HDBR), on days 5, 10, and 15 of HDBR, and day 6 of recovery. Salivary pH and salivary flow rate were measured, and the V3-V4 region of the 16S rRNA gene was sequenced and analyzed in 80 saliva samples. The results showed that there were no significant differences in salivary pH, salivary flow rate, and alpha diversity between any two time points. However, beta diversity analysis revealed significant differences between pre-HDBR and the other four time points. After HDBR, the relative abundances of Actinomyces, Parvimonas, Peptostreptococcus, Porphyromonas, Oribacterium, and Capnocytophaga increased significantly, whereas the relative abundances of Neisseria and Haemophilus decreased significantly. However, the relative abundances of Oribacterium and Capnocytophaga did not recover to the pre-HDBR level on day 6 of recovery. Network analysis revealed that the number of relationships between genera decreased, and the positive and negative correlations between genera changed in a complex manner after HDBR and did not reach their original levels on day 6 of recovery. PICRUSt analysis demonstrated that some gene functions of the salivary microbiome also changed after HDBR and remained significantly different from those before HDBR on day 6 of recovery. Collectively, 15 days of -6° HDBR had minimal effect on salivary secretion function but resulted in significant changes in the salivary microbiome, mainly manifested as an increase in oral disease-related bacteria and a decrease in oral health-related commensal bacteria. Further research is required to confirm these oral microbial changes and explore the underlying pathological mechanisms to determine the long-term effects on astronauts embarking on long-duration voyages to outer space.

Integrated analysis of the salivary microbiome and metabolome in chronic and aggressive periodontitis: A pilot study

This pilot study was designed to identify the salivary microbial community and metabolic characteristics in patients with generalized periodontitis. A total of 36 saliva samples were collected from 13 patients with aggressive periodontitis (AgP), 13 patients with chronic periodontitis (ChP), and 10 subjects with periodontal health (PH). The microbiome was evaluated using 16S rRNA gene high-throughput sequencing, and the metabolome was accessed using gas chromatography-mass spectrometry. The correlation between microbiomes and metabolomics was analyzed by Spearman’s correlation method. Our results revealed that the salivary microbial community and metabolite composition differed significantly between patients with periodontitis and healthy controls. Striking differences were found in the composition of salivary metabolites between AgP and ChP. The genera Treponema, Peptococcus, Catonella, Desulfobulbus, Peptostreptococcaceae_[XI] ([G-2], [G-3] [G-4], [G-6], and [G-9]), Bacteroidetes_[G-5], TM7_[G-5], Dialister, Eikenella, Fretibacterium, and Filifactor were present in higher levels in patients with periodontitis than in the healthy participants. The biochemical pathways that were significantly different between ChP and AgP included pyrimidine metabolism; alanine, aspartate, and glutamate metabolism; beta-alanine metabolism; citrate cycle; and arginine and proline metabolism. The differential metabolites between ChP and AgP groups, such as urea, beta-alanine, 3-aminoisobutyric acid, and thymine, showed the most significant correlations with the genera. These differential microorganisms and metabolites may be used as potential biomarkers to monitor the occurrence and development of periodontitis through the utilization of non-invasive and convenient saliva samples. This study reveals the integration of salivary microbial data and metabolomic data, which provides a foundation to further explore the potential mechanism of periodontitis.

Nisin probiotic prevents inflammatory bone loss while promoting reparative proliferation and a healthy microbiome

Dysbiosis of the oral microbiome mediates chronic periodontal disease. Realignment of microbial dysbiosis towards health may prevent disease. Treatment with antibiotics and probiotics can modulate the microbial, immunological, and clinical landscape of periodontal disease with some success. Antibacterial peptides or bacteriocins, such as nisin, and a nisin-producing probiotic, Lactococcus lactis, have not been examined in this context, yet warrant examination because of their biomedical benefits in eradicating biofilms and pathogenic bacteria, modulating immune mechanisms, and their safety profile in humans. This study's goal was to examine the potential for nisin and a nisin-producing probiotic to abrogate periodontal bone loss, the host inflammatory response, and changes in oral microbiome composition in a polymicrobial mouse model of periodontal disease. Nisin and a nisin-producing Lactococcus lactis probiotic significantly decreased the levels of several periodontal pathogens, alveolar bone loss, and the oral and systemic inflammatory host response. Surprisingly, nisin and/or the nisin-producing L. lactis probiotic enhanced the population of fibroblasts and osteoblasts despite the polymicrobial infection. Nisin mediated human periodontal ligament cell proliferation dose-dependently by increasing the proliferation marker, Ki-67. Nisin and probiotic treatment significantly shifted the oral microbiome towards the healthy control state; health was associated with Proteobacteria, whereas 3 retroviruses were associated with disease. Disease-associated microbial species were correlated with IL-6 levels. Nisin or nisin-producing probiotic's ability to shift the oral microbiome towards health, mitigate periodontal destruction and the host immune response, and promote a novel proliferative phenotype in reparative connective tissue cells, addresses key aspects of the pathogenesis of periodontal disease and reveals a new biomedical application for nisin in treatment of periodontitis and reparative medicine.

Cross-comparison of microbiota in the oropharynx, hypopharyngeal squamous cell carcinoma and their adjacent tissues through quantitative microbiome profiling

Aims

To clarify the absolute abundance of microbial communities on hypopharyngeal squamous cell carcinoma and their correlation to those in the oropharynx.

Methods

Clinical data, swabs, and tissue samples from 27 HPSCC patients were collected in this study and divided into three sampling groups: 19 oropharyngeal mucosa (OPM), 27 hypopharyngeal carcinomas tissues (HC), and 26 corresponding adjacent tissues (AT). Relative microbiome profiling (RMP), and quantitative microbiome profiling (QMP) of 16S rRNA amplicon sequencing were used for analysis.

Results

Beta-diversity showed that abundance and phylogenetic tree in OPM group were less when compared to either HC and AT. Although HC and AT were found to have similar microbiota, Bray-Curtis based beta-diversity still highlighted differences. Fusobacterium, Porphyromonas, Haemophilus, and Peptostreptococcus at the genus level in OPM were positively correlated with HC. After categorizing HC through TNM staging, the abundance of genera Fusobacterium, Parvimonas, and Dialister were found to be enhanced in higher T classifications (T3-4) and advanced stages (Ⅳ).

Conclusions

QMP yielded more comprehensive results than RMP. Dysbiosis was found in OPM groups and could be used to narrow down differential microbiome for the HC group. Genera of Parvimonas, Fusobacterium, and Dialister were deemed asrisk factors of advanced HPSCC.

Identification of the specific microbial community compositions in saliva associated with periodontitis during pregnancy

OBJECTIVE

To identify the specific microbial community compositions in saliva associated with periodontitis during pregnancy.

MATERIALS AND METHODS

Unstimulated saliva samples were collected from 53 pregnant women during weeks 24-28 of gestation, and the V3-V4 regions of the 16S rRNA gene were amplified from isolated saliva DNA and sequenced. Phylum-, genus-, and species-level taxonomic compositions were separately compared between subjects with (n = 12) and without (n = 41) periodontitis.

RESULTS

Taxa were selected using the random forest algorithm to distinguish subjects with periodontitis at each taxonomic level, and principal component biplots were constructed to visualize the composition of selected taxa in each subject. The genus-level biplot indicated that 44 subjects clustered around the origin. The prevalence of periodontitis was significantly higher among subjects outside the cluster compared with subjects inside the cluster (6/9 [67%] vs. 6/44 [14%], respectively; p = 0.002). Subjects outside the cluster also had significantly decreased abundance of Neisseria and increased abundances of several putative periodontopathic genera. Phylum- and species-level biplots failed to discriminate subjects with periodontitis more efficiently than the genus-level biplot.

CONCLUSIONS

The specific taxonomic composition of the saliva microbiota in pregnant women with periodontitis could be clearly identified at the genus level.

CLINICAL RELEVANCE

The formula developed based on the present findings, (%Treponema + %Tannerella + %Filifactor + %Anaeroglobus)/%Neisseria, can be used to predict periodontitis during pregnancy with sensitivity and specificity values of 0.67 (8/12) and 0.95 (39/41), respectively.

Comparison of Periodontopathic Bacterial Profiles of Different Periodontal Disease Severity Using Multiplex Real-Time Polymerase Chain Reaction

Periodontopathic bacteria are known to have a pivotal role in the pathogenesis of periodontitis. The aim of the study was to quantitatively compare bacterial profile of patients with different severity of periodontal disease using samples from mouthwash and the subgingival area. Further analysis was performed to evaluate the correlation between mouthwash and two subgingival sampling methods: paperpoint and gingival retraction cord; 114 subjects enrolled in the study, and were divided equally into three groups according to disease severity. Mouthwash and subgingival sampling were conducted, and the samples were quantitatively analyzed for 11 target periodontopathic bacteria using multiplex real-time PCR. There were statistically significant differences in bacterial counts and prevalence of several species between the study groups. Mouthwash sampling showed significant correlations with two different subgingival sampling methods in regard to the detection of several bacteria (e.g., ρ = 0.793 for Porphyromonas gingivalis in severe periodontitis), implying that mouthwash sampling can reflect subgingival microbiota. However, the correlation was more prominent as disease severity increased. Although bacteria in mouthwash have potential to become a biomarker, it may be more suitable for the diagnosis of severe periodontitis, rather than early diagnosis. Further research is required for the discovery of biomarkers for early diagnosis of periodontitis.