Oral Dysbiotic Communities and Their Implications in Systemic Diseases

Salivary microbiome and biomarker characteristics of diabetics with periodontitis

OBJECTIVE

To examine the characteristics of the salivary microbiome in Type 2 diabetes mellitus (T2DM) patients with or without periodontitis.

BACKGROUND

Periodontitis has been identified as clear sequelae of T2DM. This chronic oral disease also impacts the management of the clinical features of diabetes. The oral microbiome characteristics in T2DM with and without periodontitis, as well as the response of this oral microbiome to nonsurgical therapy have not been well described. Knowledge of key oral biological features could help address the observed poorer clinical presentation of T2DM patients.

METHODS

The oral microbiome in saliva of adult cohorts periodontally healthy/non-diabetic (non-periodontitis; NP; n = 31), T2DM without periodontitis (DWoP; n = 32), and T2DM with periodontitis (DWP; n = 29) were characterized by microbial molecular analysis using V3-V4 sequencing and Luminex or ELISA techniques for salivary host analytes.

RESULTS

Phyla distribution showed DWP with significantly lower levels of Firmicutes and Actinobacteria and higher levels of Fusobacteria and Spirochetes compared to the healthier groups. Approximately 10% of the detected microbial species showed significant differences in frequency and level of colonization among the DWP, DWoP, and NP samples. A subset of bacteria were significantly correlated with clinical disease features, as well as a specific repertoire of salivary analytes, in particular matrix metalloproteinase (MMP)8/MMP9, interleukin-1ß, B-cell activating factor, and resistin differed between the groups and were related to specific taxa. Principal component analysis that identified a majority of the DWP subjects microbiome was unique based upon an array of 27 taxa out of up to 255 detected in the saliva samples.

CONCLUSION

T2DM patients with periodontitis show unique oral microbiome and salivary analyte composition compared to diabetics or non-diabetic persons without periodontitis. Specific members of the oral microbiome relate directly to the clinical disease features and/or salivary biomolecules in T2DM individuals.

Association Between Healthy Eating Index-2020 and Oral Microbiome Among Postmenopausal Women

BACKGROUND

Dietary intake has been suggested to be associated with the oral microbiome, but no study has examined the association between overall diet quality and the oral microbiome.

OBJECTIVES

This study aimed to investigate the cross-sectional association between the Healthy Eating Index-2020 (HEI-2020) and the diversity and composition of the oral microbiome among participants in the Buffalo Osteoporosis and Periodontal Disease (OsteoPerio) Study.

METHODS

In 1175 postmenopausal women (mean age: 67 ± 7.0 y), we estimated the HEI-2020 scores for each woman from a food frequency questionnaire administered from 1997 to 2000. Bacterial DNA was extracted from subgingival plaque samples and analyzed using 16S ribosomal RNA sequencing. The alpha-diversity (within-sample diversity) and β-diversity (between-sample diversity) across HEI-2020 quartiles were examined using analysis of covariance and permutational multivariate analysis of variance, respectively. The associations between the HEI-2020 score and the relative abundance of microbial taxa were examined by linear regression models. The analyses were further conducted for individual components of the HEI-2020.

RESULTS

No statistically significant associations were observed between the HEI-2020 scores and alpha- or beta-diversity. However, greater consumption of seafood, plant proteins, and total protein and lower consumption of added sugars were positively associated with alpha-diversity. After we applied a false detection rate (FDR) correction, higher HEI-2020 scores were significantly associated with decreased abundance of Lautropia, Streptococcus gordonii, Cardiobacterium valvarum, and Cardiobacterium hominis, and increased abundance of Selenomonas sp. oral taxon 133 and Selenomonas dianae (FDR-adjusted P values < 0.10). Additionally, 28 other taxa were identified as being associated with HEI-2020 components.

CONCLUSIONS

Although the HEI-2020 was associated with the composition, but not the diversity, of the oral microbiome, individual HEI-2020 components were associated with both its diversity and composition. Specific dietary components may have more impact on the diversity and composition of oral microbiome than overall diet quality assessed by the HEI-2020.

Evaluation of salivary melatonin and MMP-9 levels in periodontal diseases

OBJECTIVE

The aim of this study was to evaluate salivary matrix metalloproteinase-9 (MMP-9) and melatonin levels in individuals with periodontal health, gingivitis, and periodontitis.

DESIGN

A total of 170 participants were enrolled in this study. They included 57 periodontally healthy individuals, 58 gingivitis patients, and 55 periodontitis patients. Saliva samples were collected by passive drool technique. The levels of MMP-9 and melatonin in saliva were measured biochemically using the ELISA method.

RESULTS

Salivary MMP-9 levels in the periodontitis group were significantly higher than those in the gingivitis and periodontally healthy groups, while salivary melatonin levels were significantly lower (p<0.001). A positive correlation was observed between clinical periodontal parameters and salivary MMP-9 levels, while salivary melatonin levels were negatively correlated (p<0.001). A negative correlation was also observed between salivary MMP-9 levels and salivary melatonin levels (p<0.001).

CONCLUSION

This study shows that the level of melatonin in saliva is associated with periodontal disease and with the level of MMP-9 in saliva, which plays a role in this disease.

Salivary features of periodontitis and gingivitis in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is associated with cellular abnormalities, tissue and organ dysfunctions, and periodontitis. This investigation examined the relationship between the oral microbiome and salivary biomarkers in T2DM patients with or without periodontitis. This cohort (35-80 years) included systemically healthy non-periodontitis (NP; n = 31), T2DM without periodontitis (DWoP; n = 32) and T2DM with periodontitis (DWP; n = 29). The oral microbiome [Operational Taxonomic Units (OTUs)] (16 s rRNA sequencing) and targeted host salivary biomarkers (immunoassays) were assessed. We identified 47 OTUs that were significantly different in abundance between NP samples and any disease subset or between disease subgroups. The most unique microbiome patterns were observed in the DWP group. Differences in genera/species abundance were also observed when T2DM patients were stratified by extent of periodontal inflammation and disease (i.e., generalized versus localized gingivitis/periodontitis). Salivary biomarkers showed significant elevations in MMP-8, MMP-9, resistin, IL-1β, IL-6, IFNα, and BAFF (THFSR13b) comparing generalized to localized periodontitis. Salivary analytes showed significant positive correlations with specific microbiome members, predominantly in DWP patients. Odds ratio analyses reinforced that a panel of biologic markers (IL-6, MMP-8) and bacteria (e.g., Bacteroidetes, Fusobacteria, Spirochaetes) discriminated the severity and extent of periodontal disease in this diabetic population.

Microbial functional pathways based on metatranscriptomic profiling enable effective saliva-based health assessments for precision wellness

It is increasingly recognized that an important step towards improving overall health is to accurately measure biomarkers of health from the molecular activities prevalent in the oral cavity. We present a general methodology for computationally quantifying the activity of microbial functional pathways using metatranscriptomic data. We describe their implementation as a collection of eight oral pathway scores using a large salivary sample dataset (n = 9350), and we evaluate score associations with oropharyngeal disease phenotypes within an unseen independent cohort (n = 14,129). Through this validation, we show that the relevant oral pathway scores are significantly worse in individuals with periodontal disease, acid reflux, and nicotine addiction, compared with controls. Given these associations, we make the case to use these oral pathway scores to provide molecular health insights from simple, non-invasive saliva samples, and as molecular endpoints for actionable interventions to address the associated conditions.

The oral microbial odyssey influencing chronic metabolic disease

INTRODUCTION

Since the oral cavity is the gateway to the gut, oral microbes likely hold the potential to influence metabolic disease by affecting the gut microbiota.

METHOD

A thorough review of literature has been performed to link the alterations in oral microbiota with chronic metabolic disease by influencing the gut microbiota.

RESULT

A strong correlation exists between abnormalities in oral microbiota and several systemic disorders, such as cardiovascular disease, diabetes, and obesity, which likely initially manifest as oral diseases. Ensuring adequate oral hygiene practices and cultivating diverse oral microflora are crucial for the preservation of general well-being. Oral bacteria have the ability to establish and endure in the gastrointestinal tract, leading to the development of prolonged inflammation and activation of the immune system. Oral microbe-associated prophylactic strategies could be beneficial in mitigating metabolic diseases.

CONCLUSION

Oral microbiota can have a profound impact on the gut microbiota and influence the pathogenesis of metabolic diseases.

Interplay of co-cultured chimeric adipose and gingival tissues exacerbates inflammatory dysfunction relevant to periodontal and metabolic conditions

Adipose tissue dysfunction is a key feature of metabolic syndrome, which increases the risk of periodontitis, an inflammatory disease induced by bacteria that affects the gingiva and other components of periodontal tissue. Recent studies indicate that molecules from inflamed periodontal tissue contribute to adipose tissue dysfunction. However, the cellular mechanisms and interactions between adipose tissue and gingiva driving the progression of metabolic and periodontal conditions remain unclear. To address this, we developed a chimeric (mouse/human) co-culture tissue model (which identifies the origins of species-specific cytokines) to investigate these interactions. Using tissue-specific functional cells and immunocytes, we constructed equivalents of adipose tissue (ATE) and gingiva (GTE), co-cultivating them under inflammatory conditions induced by bacterial endotoxin, lipopolysaccharide (LPS). Our findings showed that exposure to LPS resulted in a notable reduction in lipid accumulation, GLUT4 expression, and adiponectin secretion in ATE, along with increased macrophage colonies forming around lipid droplets, as well as elevated levels of triglyceride, leptin, and IL-6. In GTE, LPS triggered significant inflammatory responses, characterized by increased macrophage accumulation, elevated COX-2 expression, and heightened secretion of inflammatory cytokines. LPS also reduced epithelial thickness and the expression of keratin 19 and collagen IV, indicating impaired barrier function and gingival integrity. Co-culturing ATE with GTE exacerbated these LPS-induced harmful effects in both tissues. In conclusion, our findings suggest that interplay between gingiva and adipose tissue can intensify the inflammatory and dysfunctional changes caused by LPS. This co-culture tissue model offers a valuable tool for future studies on periodontitis and metabolic syndrome.

Peri-implantitis with a potential axis to brain inflammation: an inferential review

Peri-implantitis (PI) is a chronic, inflammatory, and infectious disease which affects dental implants and has certain similarities to periodontitis (PD). Evidence has shown that PD may be related to several types of systemic disorders, such as diabetes and insulin resistance, cardiovascular diseases, respiratory tract infections, adverse pregnancy outcomes, and neurological disorders. Furthermore, some types of bacteria in PD can also be found in PI, leading to certain similarities in the immunoinflammatory responses in the host. This review aims to discuss the possible connection between PI and neuroinflammation, using information based on studies about periodontal disorders, a topic whose connection with systemic alterations has been gaining the interest of the scientific community. Literature concerning PI, PD, and systemic disorders, such as neuroinflammation, brain inflammation, and neurological disorder, was searched in the PubMed database using different keyword combinations. All studies found were included in this narrative review. No filters were used. Eligible studies were analyzed and reviewed carefully. This study found similarities between PI and PD development, maintenance, and in the bacterial agents located around the teeth (periodontitis) or dental implants (peri-implantitis). Through the cardiovascular system, these pathologies may also affect blood-brain barrier permeability. Furthermore, scientific evidence has suggested that microorganisms from PI (as in PD) can be recognized by trigeminal fiber endings and start inflammatory responses into the trigeminal ganglion. In addition, bacteria can traverse from the mouth to the brain through the lymphatic system. Consequently, the immune system increases inflammatory mediators in the brain, affecting the homeostasis of the nervous tissue and vice-versa. Based on the interrelation of microbiological, inflammatory, and immunological findings between PD and PI, it is possible to infer that immunoinflammatory changes observed in PD can imply systemic changes in PI. This, as discussed, could lead to the development or intensification of neuroinflammatory changes, contributing to neurodegenerative diseases.

Porphyromonas gingivalis virulence factors induce toxic effects in SH-SY5Y neuroblastoma cells: GRK5 modulation as a protective strategy

Periodontitis (PDS) is a chronic inflammatory disease initiated by a dysbiosis of oral pathogenic bacterial species, such as Porphyromonas gingivalis (Pg). These bacteria can penetrate the bloodstream, releasing various endo and exotoxins that fuel the infection, and stimulate toxic inflammation in different compartments, including the brain. However, the specific mechanisms by which PDS/Pg contribute to brain disorders, such as Alzheimer's disease (AD), remain unclear. This study assessed the effects of Pg's virulence factors - lipopolysaccharide (LPS-Pg) and gingipains (gps) K (Kgp) and Rgp - on SH-SY5Y cells. Our results demonstrated that LPS-Pg activated signaling through the Toll-like receptor (TLR)-2/4 induced a significant downregulation of G protein-coupled receptor kinase 5 (GRK5). Additionally, LPS-Pg stimulation resulted in a robust increase in Tau phosphorylation (pTau) and p53 levels, while causing a marked reduction in Bcl2 and increased cell death compared to unstimulated cells (Ns). LPS-Pg also elevated inducible nitric oxide synthase (iNOS) expression, leading to oxidative damage. In cells overexpressing GRK5 via Adenovirus, LPS-Pg failed to increase iNOS and pTau levels compared to GFP control cells. High GRK5 levels also prevented the nuclear accumulation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB). Furthermore, the overexpression of a GRK5 mutant form lacking the nuclear localization signal (ΔNLS) nearly abolished LPS-Pg induced p53 and iNOS upregulation. Finally, we tested whether Kgp and Rgp mediated similar effects and our data showed that both gps caused a marked downregulation of GRK5 leading to increased p53 and pTau levels. In conclusion, this study provides further insight into the toxic effects elicited by Pg in cells and suggests that preventing GRK5 deficiency may be a valid strategy to mitigate Pg-induced toxic effects (i.e. cell death, oxidative damage, and Tau hyperphosphorylation) in SH-SY5Y cells, which are typical molecular hallmarks of neurodegenerative disorders.

Activity of Fluoroquinolones and Proton Pump Inhibitors against Resistant Oral Bacterial Biofilms, in silico and in vitro Analysis

Oral bacterial infections are a great health concern worldwide especially in diabetic patients. Emergence of antimicrobial resistance with reference to biofilms in oral cavity is of great concern. We investigated antibiotics combination with proton pump inhibitors against oral clinical isolates. The strains were identified as Staphylococcus epidermidis and Staphylococcus aureus by the 16S rRNA gene sequencing. In molecular docking, ciprofloxacin, levofloxacin, and omeprazole best fit to active pockets of transcriptional regulators 4BXI and 3QP1. None of the proton pump inhibitors were active against S. epidermidis, whereas omeprazole showed significant inhibition (MIC 3.9 μg/ml). Fluoroquinolones were active against both S. epidermidis and S. aureus. In combination analysis, a marked decrease in minimum inhibitory concentration was noticed with omeprazole (MIC 0.12 μg/ml). In antiquorum sensing experiments, a significant inhibitory zone was shown for all fluoroquinolones (14-20 mm), whereas among proton pump inhibitors, only omeprazole (12 ± 0.12 mm) was active against Chromobacterium violaceum. In combination analysis, a moderate increase in antiquorum sensing activity was recorded for ciprofloxacin, ofloxacin, and proton pump inhibitors. Further, significant S. aureus biofilm eradication was recorded using of ciprofloxacin, levofloxacin, and omeprazole combination (78 ± 2.1%). The time-kill kinetic studies indicated a bactericidal effect by ciprofloxacin: levofloxacin: omeprazole combination over 24 hrs. It was concluded that fluoroquinolone combined with omeprazole could be an effective treatment option for eradicating oral bacterial biofilms.

How well do antimicrobial mouth rinses prevent dysbiosis in an in vitro periodontitis biofilm model?

BACKGROUND

Periodontal diseases are associated with dysbiosis in the oral microbial communities. Managing oral biofilms is therefore key for preventing these diseases. Management protocols often include over-the-counter antimicrobial mouth rinses, which lack data on their effects on the oral microbiome's ecology, bacterial composition, metabolic activity, and dysbiosis resilience. This study examined the efficacy of antimicrobial mouth rinses to halt dysbiosis in in vitro oral biofilms under periodontitis-simulating conditions.

METHODS

Multispecies oral biofilms were grown on hydroxyapatite discs (HADs) and rinsed daily with one of six mouth rinses. Positive and negative controls were included. After three rinses, biofilms were analyzed with viability quantitative polymerase chain reaction and visualized using scanning electron microscopy. Supernatants of rinsed biofilms were used for metabolic activity analysis. In addition, human oral keratinocytes were exposed to rinsed biofilms to assess their inflammatory response. All outputs were analyzed for correlation using Spearman coefficient.

RESULTS

Product-related changes were observed in the rinsed biofilms. Three of the six tested mouth rinses could significantly prevent dysbiosis with ≥30% reduction in pathobiont abundance relative to the control. These biofilms had lower metabolic activity, and the exposed human oral keratinocyte produced less interleukin-8. Interleukin-8 production correlated to both pathobiont quantity and the metabolic activity of the biofilms.

CONCLUSION

Some mouth rinses could support biofilm resilience and stop dysbiosis evolution in the biofilm model, with a clear product-related effect. Such mouth rinses can be considered for patients under maintenance/supportive periodontal therapy to prevent/delay disease recurrence. Others are more useful for different periodontal therapy stages.

Oral Commensals in Healthy Individuals: A Clinicocytological Study

Background Each human being has a specific group of microorganisms that are necessary for both sustaining health and causing illness. Normally, these microorganisms maintain bio-communalism, do not harm the host, and lead to a state known as symbiosis or eubiosis. The commensal nature of these bacteria is always maintained in symbiosis and attains pathogenic potential when there is an imbalance between host immunity and microorganisms. Our study focuses on the identification and differentiation of the various commensals present in the oral cavity of healthy individuals over a given period of time. Aims and objectives This study aims to: (i) identify various commensal bacterial species present in the oral cavity; (ii) differentiate each commensal bacterial species present in the oral cavity of healthy individuals using cytological and culturing methods; (iii) identify the presence of different types of commensal bacterial species in the same individuals with the specific time intervals; (iv) compare and correlate the presence or absence of bacterial species present as a commensal in both male and female; (v) identify and characterize the commensal bacterial species present in the oral cavity of healthy individuals; (vi) investigate the consistency of commensal bacterial species presence over time and between genders.  Methodology We included sixty healthy individuals between the ages of 20 and 24 from both genders, took buccal smears once every two days for ten days, stained them with Gram stain, and grew them in blood agar and Mac Conkey agar. Results The most common commensals include Gram-positive cocci, and among them, Coagulase-negative staphylococcus species (85%) are predominant, followed by Staphylococcus aureus (13.33%), and Streptococcus species (1.67%). The presence of colonies remains the same in all three samples obtained from the same healthy individuals. Conclusion Loss of balance between commensals and pathogens can lead to dysbiosis, which results in disease.

Advances in pharmacological effects and mechanism of action of cinnamaldehyde

Cinnamaldehyde is extracted from Cinnamomum cassia and other species, providing diverse sources for varying chemical properties and therapeutic effects. Besides natural extraction, synthetic production and biotechnological methods like microbial fermentation offer scalable and sustainable alternatives. Cinnamaldehyd demonstrates a broad pharmacological range, impacting various diseases through detailed mechanisms. This review aims to encapsulate the diverse therapeutic effects of cinnamaldehyde, its molecular interactions, and its potential in clinical applications. Drawing on recent scientific studies and databases like Web of Science, PubMed, and ScienceDirect, this review outlines cinnamaldehyde's efficacy in treating inflammatory conditions, bacterial infections, cancer, diabetes, and cardiovascular and kidney diseases. It primarily operates by inhibiting the NF-κB pathway and modulating pro-inflammatory mediators, alongside disrupting bacterial cells and inducing apoptosis in cancer cells. The compound enhances metabolic health by improving glucose uptake and insulin sensitivity and offers cardiovascular protection through its anti-inflammatory and lipid-lowering effects. Additionally, it promotes autophagy in kidney disease management. Preclinical and clinical research supports its therapeutic potential, underscoring the need for further investigation into its mechanisms and safety to develop new drugs based on cinnamaldehyde.

The effect of dental material type and masticatory forces on periodontitis-derived subgingival microbiomes

Restorative dental materials can frequently extend below the gingival margin, serving as a potential haven for microbial colonization, and altering the local oral microbiome to ignite infection. However, the contribution of dental materials on driving changes of the composition of the subgingival microbiome is under-investigated. This study evaluated the microbiome-modulating properties of three biomaterials, namely resin dental composites (COM), antimicrobial piezoelectric composites (BTO), and hydroxyapatite (HA), using an optimized in vitro subgingival microbiome model derived from patients with periodontal disease. Dental materials were subjected to static or cyclic loading (mastication forces) during biofilm growth. Microbiome composition was assessed by 16S rRNA gene sequencing. Dysbiosis was measured in terms of subgingival microbial dysbiosis index (SMDI). Biomaterials subjected to cyclic masticatory loads were associated with enhanced biofilm viability except on the antibacterial composite. Biomaterials held static were associated with increased biofilm biomass, especially on HA surfaces. Overall, the microbiome richness (Chao index) was similar for all the biomaterials and loading conditions. However, the microbiome diversity (Shannon index) for the HA beams was significantly different than both composites. In addition, beta diversity analysis revealed significant differences between composites and HA biomaterials, and between both loading conditions (static and cyclic). Under static conditions, microbiomes formed over HA surfaces resulted in increased dysbiosis compared to composites through the enrichment of periopathogens, including Porphyromonas gingivalis, Porphyromonas endodontalis, and Fretibacterium spp., and depletion of commensals such as Granulicatella and Streptococcus spp. Interestingly, cyclic loading reversed the dysbiosis of microbiomes formed over HA (depletion of periopathogenes) but increased the dysbiosis of microbiomes formed over composites (enrichment of Porphyromonas gingivalis and Fusobacterim nucleatum). Comparison of species formed on both composites (control and antibacterial) showed some differences. Commercial composites enriched Selenomonas spp. and depleted Campylobacter concisus. Piezoelectric composites effectively controlled the microbiome viability without significantly impacting the species abundance. Findings of this work open new understandings of the effects of different biomaterials on the modulation of oral biofilms and the relationship with oral subgingival infections.

Porphyromonas gingivalis interaction with Candida albicans allows for aerobic escape, virulence and adherence

In the oral cavity Candida albicans interacts with many oral bacteria, including Porphyromonas gingivalis, both physically and metabolically. The aim of this in vitro study was to characterize these interactions and study their effects on the survival of P. gingivalis. First, metabolic interactions were evaluated by counting the colony forming units (CFU) after co-culturing. The results indicated that the anaerobic bacterium P. gingivalis survives under aerobic conditions when co-cultured with C. albicans. This is due to the oxygen consumption by C. albicans as determined by a reduction in survival upon the addition of Antimycin A. By measuring the protease activity, it was found that the presence of C. albicans induced gingipain activity by P. gingivalis, which is an important virulence factor. Adherence of P. gingivalis to hyphae of C. albicans was observed with a dynamic flow system. Using various C. albicans mutants, it was shown that the mechanism of adhesion was mediated by the cell wall adhesins, members of the agglutinin-like sequence (Als) family: Als3 and Als1. Furthermore, the two microorganisms could be co-cultured into forming a biofilm in which P. gingivalis can survive under aerobic culturing conditions, which was imaged using scanning electron microscopy. This study has further elucidated mechanisms of interaction, virulence acquisition and survival of P. gingivalis when co-cultured with C. albicans. Such survival could be essential for the pathogenicity of P. gingivalis in the oxygen-rich niches of the oral cavity. This study has emphasized the importance of interaction between different microbes in promoting survival, virulence and attachment of pathogens, which could be essential in facilitating penetration into the environment of the host.

Oral microbiome dysbiosis among cigarette smokers and smokeless tobacco users compared to non-users

Tobacco use significantly influences the oral microbiome. However, less is known about how different tobacco products specifically impact the oral microbiome over time. To address this knowledge gap, we characterized the oral microbiome of cigarette users, smokeless tobacco users, and non-users over 4 months (four time points). Buccal swab and saliva samples (n = 611) were collected from 85 participants. DNA was extracted from all samples and sequencing was carried out on an Illumina MiSeq, targeting the V3-V4 region of the 16S rRNA gene. Cigarette and smokeless tobacco users had more diverse oral bacterial communities, including a higher relative abundance of Firmicutes and a lower relative abundance of Proteobacteria, when compared to non-users. Non-users had a higher relative abundance of Actinomyces, Granulicatella, Haemophilus, Neisseria, Oribacterium, Prevotella, Pseudomonas, Rothia, and Veillonella in buccal swab samples, compared to tobacco users. While the most abundant bacterial genera were relatively constant over time, some species demonstrated significant shifts in relative abundance between the first and last time points. In addition, some opportunistic pathogens were detected among tobacco users including Neisseria subflava, Bulleidia moorei and Porphyromonas endodontalis. Overall, our results provide a more holistic understanding of the structure of oral bacterial communities in tobacco users compared to non-users.

The antimicrobial effect of Limosilactobacillus reuteri as probiotic on oral bacteria: A scoping review

Dysbiosis among oral microbial community in the oral cavity can lead to several oral diseases. Probiotic therapy is known to correct these imbalances. Limosilactobacillus reuteri is one of the most studied strains of probiotics and can control oral microbiota through reuterin, a wide-spectrum antimicrobial agent. The objective of this review was to evaluate the effect of the antimicrobial activity of Limosilactobacillus reuteri on the oral bacteria of humans. This review used PubMed, Scopus, EMBASE, ScienceDirect, and Google Scholar databases as bibliographic resources. Studies with matching keywords were analyzed and screened with PRISMA-ScR recommendations. Sixteen articles were selected for this review, which included a total of 832 patients. Based on this review, Limosilactobacillus reuteri has a strong antibacterial effect against Streptococcus mutans in healthy individuals but is not effective against Lactobacillus. Additionally, it has a significant antibacterial effect against Porphiromonas gingivalis in patients with periodontitis, although its effectiveness is not stable in patients with peri-implant infections. Furthermore, Limosilactobacillus reuterihas varying results against other bacteria, indicating the need for further extensive research to ensure its efficacy.

Metagenomic Analysis of Bacterial Microflora in Dental and Atherosclerotic Plaques of Patients With Internal Carotid Artery Stenosis

Background

Internal carotid artery stenosis is primarily attributed to atherosclerosis in the carotid artery bifurcation. Previous studies have detected oral bacteria in atherosclerotic lesions, suggesting an association between oral bacteria and atherosclerosis. In this study, we compared the bacterial flora of the atherosclerotic plaque in the carotid artery and dental plaque of patients with internal carotid artery stenosis using 16S ribosomal RNA (16S rRNA) metagenomic sequencing.

Methods

Fifty-four patients who underwent internal carotid endarterectomy for internal carotid artery stenosis at the Showa University Hospital between April 2016 and February 2018 were included. Polymerase chain reaction targeting the 16S rRNA gene detected bacterial DNA in the carotid plaques of 11 cases, of which only 5 could be further analyzed. Thereafter, DNA extracted from the carotid and oral plaques of these 5 cases were analyzed using metagenomic sequencing targeting 16S rRNA. In addition, their general condition and oral conditions were evaluated. The patients were classified into symptomatic and asymptomatic groups based on the presence or absence of symptoms of transient ischemic attack, and their bacterial flora was evaluated.

Results

The results demonstrated that the microflora of carotid plaques (n = 5) contained bacterial species from 55 families and 78 genera. In addition, 86.5% of the bacteria detected in the carotid plaques were also detected in oral plaques. Cariogenic and periodontopathic bacteria accounted for 27.7% and 4.7% of the bacteria in the carotid plaques, respectively.

Conclusions

These results suggest that oral bacteria are directly or indirectly involved in the pathogenesis of atherosclerosis. More extensive studies of oral commensal bacteria detected in extra-oral lesions are warranted to comprehensively investigate the role of oral bacteria in the pathogenesis of systemic diseases.

Polyphasic molecular approach to the characterization of methanogens in the saliva of Tunisian adults

OBJECTIVES

Methanogenic archaea are a minor component of human oral microbiota. Due to their relatively low abundance, the detection of these neglected microorganisms is challenging. This study concerns the presence of methanogens in salivary samples collected from Tunisian adults to evaluate their prevalence and burden using a polyphasic molecular approach.

METHODS

A total of 43 saliva samples were included. Metagenomic and standard 16S rRNA sequencing were performed as an initial screening to detect the presence of methanogens in the oral microbiota of Tunisian adults. Further investigations were performed using specific quantitative real-time PCR targeting Methanobrevibacter oralis and Methanobrevibacter smithii.

RESULTS

Methanobrevibacter was detected in 5/43 (11.62 %) saliva samples after metagenomic 16S rRNA data analysis. The presence of M. oralis was confirmed in 6/43 samples by standard 16S rRNA sequencing. Using real-time PCR, methanogens were detected in 35/43 (81.39 %) samples, including 62.79 % positive for M. oralis and 76.74 % positive for M. smithii. These findings reflect the high prevalence of both methanogens, revealed by the high sensitivity of the real-time PCR approach. Interestingly, we also noted a significant statistical association between the detection of M. smithii and poor adherence to a Mediterranean diet, indicating the impact of diet on M. smithii prevalence.

CONCLUSION

Our study showed the presence of methanogens in the oral microbiota of Tunisian adults with an unprecedented relatively high prevalence. Choice of methodology is also central to picturing the real prevalence and diversity of such minor taxa in the oral microbiota.

The impact of arthritogenic viruses in oral tissues

Arthritis and periodontitis are inflammatory diseases that share several immunopathogenic features. The expansion in the study of virus-induced arthritis has shed light on how this condition could impact other parts of the human body, including the mouth. Viral arthritis is an inflammatory joint disease caused by several viruses, most notably the alphaviruses Chikungunya virus (CHIKV), Sindbis virus (SINV), Ross River virus (RRV), Mayaro virus (MAYV), and O'nyong'nyong virus (ONNV). These viruses can induce an upsurge of matrix metalloproteinases and immune-inflammatory mediators such as Interleukin-6 (IL6), IL-1β, tumor necrosis factor, chemokine ligand 2, and receptor activator of nuclear factor kappa-B ligand in the joint and serum of infected individuals. This can lead to the influx of inflammatory cells to the joints and associated muscles as well as osteoclast activation and differentiation, culminating in clinical signs of swelling, pain, and bone resorption. Moreover, several data indicate that these viral infections can affect other sites of the body, including the mouth. The human oral cavity is a rich and diverse microbial ecosystem, and viral infection can disrupt the balance of microbial species, causing local dysbiosis. Such events can result in oral mucosal damage and gingival bleeding, which are indicative of periodontitis. Additionally, infection by RRV, CHIKV, SINV, MAYV, or ONNV can trigger the formation of osteoclasts and upregulate pro-osteoclastogenic inflammatory mediators, interfering with osteoclast activation. As a result, these viruses may be linked to systemic conditions, including oral manifestations. Therefore, this review focuses on the involvement of alphavirus infections in joint and oral health, acting as potential agents associated with oral mucosal inflammation and alveolar bone loss. The findings of this review demonstrate how alphavirus infections could be linked to the comorbidity between arthritis and periodontitis and may provide a better understanding of potential therapeutic management for both conditions.

Periodontal Disease and Alzheimer's: Insights from a Systematic Literature Network Analysis

This study investigated the relationship between periodontal disease (PD) and Alzheimer's Disease (AD) through a Systematic Literature Network Analysis (SLNA), combining bibliometric analysis with a Systematic Literature Review (SLR). Analyzing 328 documents from 2000 to 2023, we utilized the Bibliometrix R-package for multiple bibliometric analysis. The SLR primarily centered on the 47 most globally cited papers, highlighting influential research. Our study reveals a positive correlation between Periodontal Disease (PD) and Alzheimer's Disease (AD), grounded in both biological plausibility and a comprehensive review of the literature, yet the exact causal relationship remains a subject of ongoing scientific investigation. We conducted a detailed analysis of the two main pathways by which PD could contribute to brain inflammation: (a) the Inflammatory Cascade, and (b) Microbial Involvement. The results of our SLNA emphasize the importance of oral health in reducing Alzheimer's risk, suggesting that managing periodontal health could be an integral part of Alzheimer's prevention and treatment strategies. The insights from this SLNA pave the way for future research and clinical practices, underscoring the necessity of interdisciplinary methods in both the investigation and treatment of neurodegenerative diseases like Alzheimer's. Furthermore, our study presents a prospective research roadmap to support ongoing advancement in this field.

An exploratory study of children with caries and its relationship to SARS-CoV-2

This exploratory study investigated whether children with dental decay were more likely to have COVID-19 than those without caries. The children underwent dental inspection and blood collection for detection of SARS-CoV-2 antibodies. Fifty-four children aged 6 to 9 years participated in the survey, which was conducted between March and June 2020 in the municipality of Ipojuca, Pernambuco, Brazil. The diagnosis of caries was performed using the dmft and DMFT indices. Parents reported signs and symptoms of sickness in their children during this period. The serology test aimed to verify the immune response of the children to coronavirus by detecting IgM/IgG antibodies. Statistical analyses were performed at P < 0.05. The majority of the children presented caries (68.5%). Of the nine children who tested positive for COVID-19 (16.7%), eight presented IgG antibodies to the virus, and only one had IgG and IgM antibodies to SARS-CoV2. Children who tested positive for SARS-CoV-2 had a higher percentage of caries lesions than those who tested negative for SARS-CoV-2 (77.8% vs 65.9%), but this difference was not statistically significant.

DAMPs and alarmin gene expression patterns in aging healthy and diseased mucosal tissues

Introduction

Periodontitis is delineated by a dysbiotic microbiome at sites of lesions accompanied by a dysregulated persistent inflammatory response that undermines the integrity of the periodontium. The interplay of the altered microbial ecology and warning signals from host cells would be a critical feature for maintaining or re-establishing homeostasis in these tissues.

Methods

This study used a nonhuman primate model (Macaca mulatta) with naturally-occurring periodontitis (n = 34) and experimental ligature-induced periodontitis (n = 36) to describe the features of gene expression for an array of damage-associate molecular patterns (DAMPs) or alarmins within the gingival tissues. The animals were age stratified into: ≤3 years (Young), 7-12 years (Adolescent), 12-15 years (Adult) and 17-23 years (Aged). Gingival tissue biopsies were examined via microarray. The analysis focused on 51 genes representative of the DAMPs/alarmins family of host cell warning factors and 18 genes associated with tissue destructive processed in the gingival tissues. Bacterial plaque samples were collected by curette sampling and 16S rRNA gene sequences used to describe the oral microbiome.

Results

A subset of DAMPs/alarmins were expressed in healthy and naturally-occurring periodontitis tissues in the animals and suggested local effects on gingival tissues leading to altered levels of DAMPs/alarmins related to age and disease. Significant differences from adult healthy levels were most frequently observed in the young and adolescent animals with few representatives in this gene array altered in the healthy aged gingival tissues. Of the 51 target genes, only approximately ⅓ were altered by ≥1.5-fold in any of the age groups of animals during disease, with those increases observed during disease initiation. Distinctive positive and negative correlations were noted with the DAMP/alarmin gene levels and comparative expression changes of tissue destructive molecules during disease across the age groups. Finally, specific correlations of DAMP/alarmin genes and relative abundance of particular microbes were observed in health and resolution samples in younger animals, while increased correlations during disease in the older groups were noted.

Conclusions

Thus, using this human-like preclinical model of induced periodontitis, we demonstrated the dynamics of the activation of the DAMP/alarmin warning system in the gingival tissues that showed some specific differences based on age.

Host Transcriptional Regulatory Genes and Microbiome Networks Crosstalk through Immune Receptors Establishing Normal and Tumor Multiomics Metafirm of the Oral-Gut-Lung Axis

The microbiome has shown a correlation with the diet and lifestyle of each population in health and disease, the ability to communicate at the cellular level with the host through innate and adaptative immune receptors, and therefore an important role in modulating inflammatory process related to the establishment and progression of cancer. The oral cavity is one of the most important interaction windows between the human body and the environment, allowing the entry of an important number of microorganisms and their passage across the gastrointestinal tract and lungs. In this review, the contribution of the microbiome network to the establishment of systemic diseases like cancer is analyzed through their synergistic interactions and bidirectional crosstalk in the oral-gut-lung axis as well as its communication with the host cells. Moreover, the impact of the characteristic microbiota of each population in the formation of the multiomics molecular metafirm of the oral-gut-lung axis is also analyzed through state-of-the-art sequencing techniques, which allow a global study of the molecular processes involved of the flow of the microbiota environmental signals through cancer-related cells and its relationship with the establishment of the transcription factor network responsible for the control of regulatory processes involved with tumorigenesis.

Effects of long-term metal exposure on the structure and co-occurrence patterns of the oral microbiota of residents around a mining area

Objectives

The aim of our study was to investigate the impact of long-term exposure to heavy metals on the microbiome of the buccal mucosa, to unveil the link between environmental contamination and the oral microbial ecosystem, and to comprehend its potential health implications.

Methods

Subjects were divided into two groups: the exposure group and the control group. We collected samples of buccal mucosa, soil, and blood, and conducted microbial diversity analysis on both groups of oral samples using 16S rRNA gene sequencing. The concentrations of heavy metals in blood and soil samples were also determined. Additionally, microbial networks were constructed for the purpose of topological analysis.

Results

Due to long-term exposure to heavy metals, the relative abundance of Rhodococcus, Delftia, Fusobacterium, and Peptostreptococcus increased, while the abundance of Streptococcus, Gemella, Prevotella, Granulicatella, and Porphyromonas decreased. The concentrations of heavy metals in the blood (Pb, Cd, Hg, and Mo) were associated with the growth of Rhodococcus, Delftia, Porphyromonas, and Gemella. In addition, the relative abundances of some pathogenic bacteria, such as Streptococcus anginosus, S. gordonii, and S. mutans, were found to be enriched in the exposure group. Compared to the exposure group network, the control group network had a greater number of nodes, modules, interactive species, and keystone taxa. Module hubs and connectors in the control group converted into peripherals in the exposure group, indicating that keystone taxa changed. Metals in the blood (Pb, Cd, Hg, and Mo) were drivers of the microbial network of the buccal mucosa, which can have adverse effects on the network, thus providing conditions for the occurrence of certain diseases.

Conclusion

Long-term exposure to multiple metals perturbs normal bacterial communities in the buccal mucosa of residents in contaminated areas. This exposure reduces the complexity and stability of the microbial network and increases the risk of developing various diseases.

The homeostasis and therapeutic applications of innate and adaptive immune cells in periodontitis

OBJECTIVES

Periodontitis (PD) is one of the most common dental disorders. This chronic oral inflammation is caused by complicated interrelations between bacterial infections, dysregulated immune reactions, and environmental risk factors. A dysregulated immune response can lead to inflammatory bone resorption by allowing the recruitment of pro-inflammatory immune cells to the periodontal tissues.

SUBJECTS

The recruitment of innate and adaptive immune cells in PD initiates the acute and following chronic inflammatory processes. The inflamed tissues, on the other hand, can be restored if the anti-inflammatory lineages are predominantly established in the periodontal tissues. Therefore, we aimed to review the published literature to provide an overview of the existing knowledge about the role of immune cells in PD, as well as their possible therapeutic applications.

RESULTS

Experimental studies showed that drugs/systems that negatively regulate inflammatory cells in the body, as well as interventions aimed at increasing the number of anti-inflammatory cells such as Tregs and Bregs, can both help in the healing process of PD.

CONCLUSION

Targeting immune cells or their positive/negative manipulations has been demonstrated to be an effective therapeutic method. However, to use this sort of immunotherapy in humans, further pre-clinical investigations, as well as randomized clinical trials, are required.

Periodontitis and progression of gastrointestinal cancer: current knowledge and future perspective

Periodontitis is a polymicrobial disorder caused by dysbiosis. Porphyromonas gingivalis (P.gingivalis) and Fusobacterium nucleatum (F.nucleatum) are pathobiont related to periodontitis pathogenesis and were found to be abundant in the intestinal mucosa of inflammatory bowel disease (IBD) and colorectal cancer (CRC) patients. Besides, periodontal infections have been found in a variety of tissues and organs, indicating that periodontitis is not just an inflammation limited to the oral cavity. Considering the possible translocation of pathobiont from the oral cavity to the gastrointestinal (GI) tract, this study aimed to review the published articles in this field to provide a comprehensive view of the existing knowledge about the relationship between periodontitis and GI malignancies by focusing on the oral/gut axis.

Exploring the use of preprints in dentistry

OBJECTIVE

This study aims to assess the use, impact, and dissemination of preprints in dentistry.

METHODS

This is a meta-research study with a cross-sectional design. We included preprints published in dentistry, regardless of the year of publication. Searches were performed in the medRxiv.org and Preprints.org platforms and restricted to English. One researcher extracted the data, and another researcher verified data consistency. The following data were extracted: year of publication, country of the corresponding author, number of abstract and full-text views and downloads, Altmetric attention score, whether the preprint was mentioned in other servers such as Twitter and Publons, number of mentions in other servers, number of citations in the Dimensions database, and whether the preprint had already been published in a peer-reviewed journal. If already published, we extracted the journal's impact factor (JCR 2021) and the number of citations in the Dimensions database. We conducted a descriptive analysis of the extracted characteristics and explored relationships between metrics using the Spearman correlation.

RESULTS

We identified 276 preprints. Most of the studies were published between 2020 and 2022 (n = 229), especially those from ten countries. The most-cited preprint and published article are the same study. Only the correlation between the number of preprint citations and peer-reviewed article citations in the Dimensions database showed a large positive association (Spearman's rho = 0.5809).

CONCLUSION

Preprints gained popularity over the last several years due to the COVID-19 pandemic and reached a larger audience, especially on platforms such as Twitter.

CLINICAL SIGNIFICANCE

Preprint publishing allows faster dissemination of science for the benefit of society.

Oral microbiota in human health and disease: A perspective

The evolution of medical knowledge about oral microbiota has increased awareness of its important role for the entire human body health. A wide range of microbial species colonizing the oral cavity interact both with each other and with their host through complex pathways. Usually, these interactions lead to a harmonious coexistence (i.e. eubiosis). However, several factors - including diet, poor oral hygiene, tobacco smoking, and certain medications, among others - can disrupt this weak homeostatic balance (i.e. dysbiosis) with potential implications on both oral (i.e. development of caries and periodontal disease) and systemic health. This article is thus aimed at providing an overview on the importance of oral microbiota in mediating several physiological and pathological conditions affecting human health. In this context, strategies based on oral hygiene and diet as well as the role of probiotics supplementation are discussed.

The role of microbiome-host interactions in the development of Alzheimer´s disease

Alzheimer`s disease (AD) is the most prevalent cause of dementia. It is often assumed that AD is caused by an aggregation of extracellular beta-amyloid and intracellular tau-protein, supported by a recent study showing reduced brain amyloid levels and reduced cognitive decline under treatment with a beta-amyloid-binding antibody. Confirmation of the importance of amyloid as a therapeutic target notwithstanding, the underlying causes of beta-amyloid aggregation in the human brain, however, remain to be elucidated. Multiple lines of evidence point towards an important role of infectious agents and/or inflammatory conditions in the etiology of AD. Various microorganisms have been detected in the cerebrospinal fluid and brains of AD-patients and have thus been hypothesized to be linked to the development of AD, including Porphyromonas gingivalis (PG) and Spirochaetes. Intriguingly, these microorganisms are also found in the oral cavity under normal physiological conditions, which is often affected by multiple pathologies like caries or tooth loss in AD patients. Oral cavity pathologies are mostly accompanied by a compositional shift in the community of oral microbiota, mainly affecting commensal microorganisms and referred to as 'dysbiosis'. Oral dysbiosis seems to be at least partly mediated by key pathogens such as PG, and it is associated with a pro-inflammatory state that promotes the destruction of connective tissue in the mouth, possibly enabling the translocation of pathogenic microbiota from the oral cavity to the nervous system. It has therefore been hypothesized that dysbiosis of the oral microbiome may contribute to the development of AD. In this review, we discuss the infectious hypothesis of AD in the light of the oral microbiome and microbiome-host interactions, which may contribute to or even cause the development of AD. We discuss technical challenges relating to the detection of microorganisms in relevant body fluids and approaches for avoiding false-positives, and introduce the antibacterial protein lactoferrin as a potential link between the dysbiotic microbiome and the host inflammatory reaction.

Differential oral microbiome in nonhuman primates from periodontitis-susceptible and periodontitis-resistant matrilines

Rhesus monkeys (n = 36) exhibiting a healthy periodontium at baseline were used to induce progressing periodontitis through ligature placement around premolar/molar teeth. Bacterial samples were collected at baseline, 0.5, 1, and 3 months of disease and at 5 months for disease resolution. The animals were distributed into two groups (18/group): 3-7 years (young) and 12-23 years (adult) and stratified based upon matriline susceptibility to periodontitis (PDS, susceptible; PDR, resistant). A total of 444 operational taxonomic units (OTUs) with 100 microbes representing a core microbiome present in ≥75% of the samples were identified. Only 48% of the major phylotypes overlapped in the PDS and PDR samples. Different OTU abundance patterns were seen in young animals from the PDS and PDR matrilines, with qualitative similarities during disease and the relative abundance of phylotypes becoming less diverse. In adults, 23 OTUs were increased during disease in PDS samples and 24 in PDR samples; however, only five were common between these groups. Greater diversity of OTU relative abundance at baseline was observed with adult compared to young oral samples from both the PDS and PDR groups. With disease initiation (2 weeks), less diversity of relative abundance and some distinctive increases in specific OTUs were noted. By 1 month, there was considerable qualitative homogeneity in the major OTUs in both groups; however, by 3 months, there was an exacerbation of both qualitative and quantitative differences in the dominant OTUs between the PDS and PDR samples. These results support that some differences in disease expression related to matriline (familial) periodontitis risk may be explained by microbiome features.

Mucin glycans drive oral microbial community composition and function

Human microbiome composition is closely tied to health, but how the host manages its microbial inhabitants remains unclear. One important, but understudied, factor is the natural host environment: mucus, which contains gel-forming glycoproteins (mucins) that display hundreds of glycan structures with potential regulatory function. Leveraging a tractable culture-based system to study how mucins influence oral microbial communities, we found that mucin glycans enable the coexistence of diverse microbes, while resisting disease-associated compositional shifts. Mucins from tissues with unique glycosylation differentially tuned microbial composition, as did isolated mucin glycan libraries, uncovering the importance of specific glycan patterns in microbiome modulation. We found that mucins shape microbial communities in several ways: serving as nutrients to support metabolic diversity, organizing spatial structure through reduced aggregation, and possibly limiting antagonism between competing taxa. Overall, this work identifies mucin glycans as a natural host mechanism and potential therapeutic intervention to maintain healthy microbial communities.

The oral microbiome in autoimmune diseases: friend or foe?

The human body is colonized by abundant and diverse microorganisms, collectively known as the microbiome. The oral cavity has more than 700 species of bacteria and consists of unique microbiome niches on mucosal surfaces, on tooth hard tissue, and in saliva. The homeostatic balance between the oral microbiota and the immune system plays an indispensable role in maintaining the well-being and health status of the human host. Growing evidence has demonstrated that oral microbiota dysbiosis is actively involved in regulating the initiation and progression of an array of autoimmune diseases.Oral microbiota dysbiosis is driven by multiple factors, such as host genetic factors, dietary habits, stress, smoking, administration of antibiotics, tissue injury and infection. The dysregulation in the oral microbiome plays a crucial role in triggering and promoting autoimmune diseases via several mechanisms, including microbial translocation, molecular mimicry, autoantigen overproduction, and amplification of autoimmune responses by cytokines. Good oral hygiene behaviors, low carbohydrate diets, healthy lifestyles, usage of prebiotics, probiotics or synbiotics, oral microbiota transplantation and nanomedicine-based therapeutics are promising avenues for maintaining a balanced oral microbiome and treating oral microbiota-mediated autoimmune diseases. Thus, a comprehensive understanding of the relationship between oral microbiota dysbiosis and autoimmune diseases is critical for providing novel insights into the development of oral microbiota-based therapeutic approaches for combating these refractory diseases.

Exogenous monocyte myeloid-derived suppressor cells ameliorate immune imbalance, neuroinflammation and cognitive impairment in 5xFAD mice infected with Porphyromonas gingivalis

BACKGROUND

Periodontitis is closely associated with the pathogenesis of Alzheimer's disease (AD). Porphyromonas gingivalis (Pg), the keystone periodontal pathogen, has been reported in our recent study to cause immune-overreaction and induce cognitive impairment. Monocytic myeloid-derived suppressor cells (mMDSCs) possess potent immunosuppressive function. It is unclear whether mMDSCs-mediated immune homeostasis is impaired in AD patients with periodontitis, and whether exogenous mMDSCs could ameliorate immune-overreaction and cognitive impairment induced by Pg.

METHODS

To explore the influence of Pg on cognitive function, neuropathology and immune balance in vivo, 5xFAD mice were treated with live Pg by oral gavage, three times a week for 1 month. The cells of peripheral blood, spleen and bone marrow from 5xFAD mice were treated with Pg to detect the proportional and functional alterations of mMDSCs in vitro. Next, exogenous mMDSCs were sorted from wild-type healthy mice and intravenously injected into 5xFAD mice that were infected with Pg. We used behavioral tests, flow cytometry and immunofluorescent staining to evaluate whether exogenous mMDSCs could ameliorate the cognitive function, immune homeostasis and reduce neuropathology exacerbated by Pg infection.

RESULTS

Pg exacerbated cognitive impairment in 5xFAD mice, with the deposition of amyloid plaque and increased number of microglia in the hippocampus and cortex region. The proportion of mMDSCs decreased in Pg-treated mice. In addition, Pg reduced the proportion and the immunosuppressive function of mMDSCs in vitro. Supplement of exogenous mMDSCs improved the cognitive function, and enhanced the proportions of mMDSCs and IL-10⁺ T cells of 5xFAD mice infected with Pg. At the same time, supplement of exogenous mMDSCs increased the immunosuppressive function of endogenous mMDSCs while decreased the proportions of IL-6⁺ T cells and IFN-γ⁺ CD4⁺ T cells. In addition, the deposition of amyloid plaque decreased while the number of neurons increased in the hippocampus and cortex region after the supplement of exogenous mMDSCs. Furthermore, the number of microglia increased with an increase in the proportion of M2 phenotype.

CONCLUSIONS

Pg can reduce the proportion of mMDSCs, induce immune-overreaction, and exacerbate the neuroinflammation and cognitive impairment in 5xFAD mice. Supplement of exogenous mMDSCs can reduce the neuroinflammation, immune imbalance and cognitive impairment in 5xFAD mice infected with Pg. These findings indicate the mechanism of AD pathogenesis and Pg-mediated promotion of AD, and provide a potential therapeutic strategy for AD patients.

Formation of a biofilm matrix network shapes polymicrobial interactions

Staphylococcus aureus colonizes the same ecological niche as many commensals. However, little is known about how such commensals modulate staphylococcal fitness and persistence. Here we report a new mechanism that mediates dynamic interactions between a commensal streptococcus and S. aureus. Commensal Streptococcus parasanguinis significantly increased the staphylococcal biofilm formation in vitro and enhanced its colonization in vivo. A streptococcal biofilm-associated protein BapA1, not fimbriae-associated protein Fap1, is essential for dual-species biofilm formation. On the other side, three staphylococcal virulence determinants responsible for the BapA1-dependent dual-species biofilm formation were identified by screening a staphylococcal transposon mutant library. The corresponding staphylococcal mutants lacked binding to recombinant BapA1 (rBapA1) due to lower amounts of eDNA in their culture supernatants and were defective in biofilm formation with streptococcus. The rBapA1 selectively colocalized with eDNA within the dual-species biofilm and bound to eDNA in vitro, highlighting the contributions of the biofilm matrix formed between streptococcal BapA1 and staphylococcal eDNA to dual-species biofilm formation. These findings have revealed an additional new mechanism through which an interspecies biofilm matrix network mediates polymicrobial interactions.

The oral microbiome in the pathophysiology of cardiovascular disease

Despite advances in our understanding of the pathophysiology of many cardiovascular diseases (CVDs) and expansion of available therapies, the global burden of CVD-associated morbidity and mortality remains unacceptably high. Important gaps remain in our understanding of the mechanisms of CVD and determinants of disease progression. In the past decade, much research has been conducted on the human microbiome and its potential role in modulating CVD. With the advent of high-throughput technologies and multiomics analyses, the complex and dynamic relationship between the microbiota, their 'theatre of activity' and the host is gradually being elucidated. The relationship between the gut microbiome and CVD is well established. Much less is known about the role of disruption (dysbiosis) of the oral microbiome; however, interest in the field is growing, as is the body of literature from basic science and animal and human investigations. In this Review, we examine the link between the oral microbiome and CVD, specifically coronary artery disease, stroke, peripheral artery disease, heart failure, infective endocarditis and rheumatic heart disease. We discuss the various mechanisms by which oral dysbiosis contributes to CVD pathogenesis and potential strategies for prevention and treatment.

Periodontitis: An Oral Disease with Severe Consequences

Periodontitis, being a multifactorial disorder is found to be the most common oral disease denoted by the inflammation of gingiva and resorption of tooth supporting alveolar bone. The disease being closely linked with fast life style and determined by unhygienic behavioural factors, the internal milieu of oral cavity and formation of plaque biofilm on the dental and gingival surfaces. Porphyromonas gingivalis, being the major keystone pathogen of the periodontal biofilm evokes host immune responses that causes damage of gingival tissues and resorption of bones. The biofilm associated microbial community progressively aggravates the condition resulting in chronic inflammation and finally tooth loss. The disease often maintains bidirectional relationship with different systemic, genetic, autoimmune, immunodeficiency diseases and even psychological disorders. The disease can be diagnosed and predicted by various genetic, radiographic and computer-aided design (CAD) & computer-aided engineering (CAE) and artificial neural network (ANN). The elucidation of genetic background explains the inheritance of the disease. The therapeutic approaches commonly followed include mechanical removal of dental plaque with the use of systemic antibiotics. Awareness generation amongst local people, adoption of good practice of timely tooth brushing preferably with fluoride paste or with nanoconjugate pastes will reduce the chance of periodontal plaque formation. Modern tissue engineering technology like 3D bioprinting of periodontal tissue may help in patient specific flawless regeneration of tooth structures and associated bones.

Oral microbiota in cancer: could the bad guy turn good with application of polyphenols?

The human oral cavity is comprised of dynamic and polynomial microbes which uniquely reside in the microenvironments of oral cavities. The cumulative functions of the symbiotic microbial communities maintain normal homeostasis; however, a shifted microbiota yields a dysbiosis state, which produces local and systemic diseases including dental caries, periodontitis, cancer, obesity and diabetes. Recent research reports claim that an association occurs between oral dysbiosis and the progression of different types of cancers including oral, gastric and pancreatic ones. Different mechanisms are proposed for the development of cancer, such as induction of inflammatory reactions, production of carcinogenic materials and alteration of the immune system. Medications are available to treat these associated diseases; however, the current strategies may further worsen the disease by unwanted side effects. Natural-derived polyphenol molecules significantly inhibit a wide range of systemic diseases with fewer side effects. In this review, we have displayed the functions of the oral microbes and we have extended the report regarding the role of polyphenols in oral microbiota to maintain healthy conditions and prevention of diseases with emphasis on the treatment of oral microbiota-associated cancer.

Associations between Periodontitis and COPD: An Artificial Intelligence-Based Analysis of NHANES III

A number of cross-sectional epidemiological studies suggest that poor oral health is associated with respiratory diseases. However, the number of cases within the studies was limited, and the studies had different measurement conditions. By analyzing data from the National Health and Nutrition Examination Survey III (NHANES III), this study aimed to investigate possible associations between chronic obstructive pulmonary disease (COPD) and periodontitis in the general population. COPD was diagnosed in cases where FEV (1)/FVC ratio was below 70% (non-COPD versus COPD; binary classification task). We used unsupervised learning utilizing k-means clustering to identify clusters in the data. COPD classes were predicted with logistic regression, a random forest classifier, a stochastic gradient descent (SGD) classifier, k-nearest neighbors, a decision tree classifier, Gaussian naive Bayes (GaussianNB), support vector machines (SVM), a custom-made convolutional neural network (CNN), a multilayer perceptron artificial neural network (MLP), and a radial basis function neural network (RBNN) in Python. We calculated the accuracy of the prediction and the area under the curve (AUC). The most important predictors were determined using feature importance analysis. Results: Overall, 15,868 participants and 19 feature variables were included. Based on k-means clustering, the data were separated into two clusters that identified two risk characteristic groups of patients. The algorithms reached AUCs between 0.608 (DTC) and 0.953% (CNN) for the classification of COPD classes. Feature importance analysis of deep learning algorithms indicated that age and mean attachment loss were the most important features in predicting COPD. Conclusions: Data analysis of a large population showed that machine learning and deep learning algorithms could predict COPD cases based on demographics and oral health feature variables. This study indicates that periodontitis might be an important predictor of COPD. Further prospective studies examining the association between periodontitis and COPD are warranted to validate the present results.

Analysis of subgingival micro-organisms based on multi-omics and Treg/Th17 balance in type 2 diabetes with/without periodontitis

Type 2 diabetes mellitus (T2DM) and periodontitis are common and interrelated diseases, resulting in altered host response microbiota. The subgingival micro-organisms play a key role in periodontitis pathogenesis. To assess the shift of subgingival microbiome and metabolome in T2DM, we performed an analysis of the subgingival microbiome in patients with T2DM (n = 20) compared with non-diabetes (ND) subjects (n = 21). Furthermore, patients were subdivided into 10 T2DM with periodontitis (DP), 10 T2DM without periodontitis (DNP), 10 periodontitis (P), and 11 healthy control (H) groups. 16SrRNA gene sequencing combined with ultra high-performance liquid chromatography-mass spectrometry (UHPLC-MS) based metabolomics was performed in all participants. T lymphocyte immunity was analyzed by flow cytometry. Furthermore, the network relationship among subgingival micro-organisms, metabolites, blood glucose level, and T lymphocyte immunity were analyzed. The results showed that the difference of the subgingival microbiome from healthy to periodontitis status was less prominent in T2DM compared with ND, though the clinical signs of disease were similar. The bacteria Eubacterium nodatum group, Filifactor, Fretibacterium, Peptostreptococcus, and Desulfovibrio, amongst others, may be important in the pathopoiesia of periodontitis in the T2DM state. In addition, some dominant bacteria showed network relationships. The Treg/Th17 ratio was lower in the DP and DNP groups than in the P and H groups-though that of P was lower than for H. The percentage of CD4+/CD8+ PD1 and CD8+ PDL1 was higher in the DP and DNP groups than in the H group; the percentage of CD8+ PDL1 was higher in the DP than P groups. Subgingival micro-organisms in periodontitis had a significant metabolic shift in terms of their signature metabolites. Butyrate metabolism and phenylalanine metabolism may play a role in the pathogenesis of periodontitis with/without T2DM. Specifically, biphenyl degradation, tryptophan metabolism, and the two-component system may play important roles in periodontitis with T2DM. Lastly, the network relationship among subgingival micro-organisms, metabolites, blood glucose level, and T lymphocyte immunity were unbalanced. This study identified the changes in the subgingival microbiome associated with periodontitis in T2DM, as well as the associated network between bacterial flora, metabolism dysbiosis, and immune regulation.

The systemic oral health connection: Biofilms

Frequently, periodontal health and it's associated oral biofilm has not been addressed in those patients who have systemic health issues, especially those who are not responding to medical treatment via their physician. Oral biofilm may be present in the periodontal sulcus in the absence of clinical disease of periodontal disease (bleeding on probing, gingival inflammation) and periodontal reaction is dependent on the patient's immune response to the associated bacterial and their byproducts. Increasing evidence has been emerging the past decade connecting oral biofilm with systemic conditions, either initiating them or complicating those medical conditions. The patient's health needs to be thought of as a whole-body system with connections that may originate in the oral cavity and have distant affects throughout the body. To maximize total health, a coordination in healthcare needs to be a symbiosis between the physician and dentist to eliminate the oral biofilm and aid in prevention of systemic disease or minimize those effects to improve the patient's overall health and quality of life. Various areas of systemic health have been associated with the bacteria and their byproducts in the oral biofilm. Those include cardiovascular disease, chronic kidney disease, diabetes, pulmonary disease, prostate cancer, colon cancer, pancreatic cancer, pre-term pregnancy, erectile dysfunction Alzheimer's disease and Rheumatoid arthritis. This article will discuss oral biofilm, its affects systemically and review the medical conditions associated with the oral systemic connection with an extensive review of the literature.

The antibiofilm activity of selected substances used in oral health prophylaxis

Oral health is a window to a patient’s general well-being. Balance in oral microbiome functions is crucial for health maintenance. A state of oral dysbiosis may lead to a variety of local and systemic pathological conditions. The presence of dental plaque is related to the majority of oral infections. Proper oral hygiene is crucial and the most economic practice contributing to oral health prophylaxis. Aside from prophylactic treatments provided by dental practitioners, mouth rinses, containing antimicrobial agents, are one of the possible tools used for oral care. Our study was to determine whether available mouth rinses and selected products dedicated for professional use are efficient to eradicate biofilm formed by reference and clinical strains of Streptococcus mutans, Streptococcus sanguinis, Streptococcus oralis, Streptococcus mitis, Staphylococcus aureus, Enterococcus faecalis, Lactobacillus rhamnosus and Candida albicans on the surface of hydroxyapatite – major mineral component of a tooth. Therefore, such antimicrobials as chlorhexidine, cetylpyridine chloride, polyhexanide, silver nanoparticles, sulphonated phenolics, and natural antiplaque essential oils and coconut oil were analyzed. Applied experimental settings in in vitro models were designed to reflect accurately the recommended use of the tested substances, therefore four types of eradication procedure were conducted. Sialorrhea simulation was also performed to evaluate antibiofilm potential of diluted mouth rinses. Biofilm was investigated with quantitative method where absorbance values were measured. Statistical differences were assessed using the Kruskal–Wallis test with a post-hoc Dunnett’s analysis. Results have shown that biofilms displayed a diversified sensitivity to the tested antimicrobials. The highest antibiofilm activity was detected for cetylpyridine chloride while the lowest for chlorhexidine. However the differences in E. faecalis biofilm reduction observed after the use of these two compounds were not statistically significant (p > 0.05), whereas all observed differences in S. aureus survival after exposure to the examined antimicrobial agents were statistically significant (p < 0.5). The PHMB, both in standard and in sialorrhea simulated conditions had the highest potential against streptococci. The coconut oil reduced C. albicans fungus biofilm by 65.48% but low eradication level was observed in case of bacterial biofilms. The dehydrating mechanism of action of sulfonated phenolics turned out to be ineffective against streptococcal biofilm which in turn was effectively eradicated by silver nanoparticles. The implementation of Antibiofilm Dressing's Activity Measurement method allowed to observe strain-related differences in terms of antimicrobial sensitivity. The obtained results may be introduced in everyday out-patient dental plaque prophylaxis as well as clinical environment.

A pilot clinical and radiographic study on the association between periodontitis and serious COVID-19 infection

BACKGROUND

During the pandemic of COVID-19, the scientific community tried to identify the risk factors that aggravate the viral infection. Oral health and specifically periodontitis have been shown to have a significant impact on overall health. Current, yet limited, evidence suggests a link between periodontal status and severity of COVID-19 infection.

OBJECTIVES

The present pilot study aimed to assess whether younger patients (≤60 years) that have been hospitalized in the intensive care unit (ICU) for severe COVID-19 infection were susceptible to severe periodontitis.

MATERIAL AND METHODS

All dentate patients ≤60 years of age diagnosed with COVID-19 and surviving hospitalization in the ICU were considered for inclusion. Susceptibility to periodontitis was determined by assessing radiographic bone loss (RBL) in recent dental radiographs (posterior bitewings, periapical, and panoramic X-rays). RBL in % was obtained from the most affected tooth and patients were classified into: Stage I, RBL ≤ 15%; Stage II, RBL = 15%-33% and Stage III/IV, RBL ≥ 33%. The grade was defined using the RBL to age ratio on the most severely affected tooth. Patients were attributed to: Grade A, ratio <0.25; Grade B, ratio 0.25-1 and Grade C, ratio >1. Patients classified into Stage III/IV and Grade C were considered highly susceptible to periodontitis.

RESULTS

Of 87 eligible patients, 30 patients were finally assessed radiographically and/or clinically; from the remaining 57 patients, 16 refused participation for various reasons and 41 could not be reached. Based on the radiographic assessment, all patients were periodontally compromised. Half of them were classified with Stage III/IV and Grade B or C; 26.7% were classified with Stage III/IV and Grade C.

CONCLUSIONS

The present pilot study showed that about half of the patients suffering from severe forms of COVID-19 infection in need of ICU admission suffered also from severe periodontitis, and about one-fourth of them were highly susceptible to it.

Changes in Oral Microbial Diversity in a Piglet Model of Traumatic Brain Injury

Dynamic changes in the oral microbiome have gained attention due to their potential diagnostic role in neurological diseases such as Alzheimer's disease and Parkinson's disease. Traumatic brain injury (TBI) is a leading cause of death and disability in the United States, but no studies have examined the changes in oral microbiome during the acute stage of TBI using a clinically translational pig model. Crossbred piglets (4-5 weeks old, male) underwent either a controlled cortical impact (TBI, n = 6) or sham surgery (sham, n = 6). The oral microbiome parameters were quantified from the upper and lower gingiva, both buccal mucosa, and floor of the mouth pre-surgery and 1, 3, and 7 days post-surgery (PS) using the 16S rRNA gene. Faith's phylogenetic diversity was significantly lower in the TBI piglets at 7 days PS compared to those of sham, and beta diversity at 1, 3, and 7 days PS was significantly different between TBI and sham piglets. However, no significant changes in the taxonomic composition of the oral microbiome were observed following TBI compared to sham. Further studies are needed to investigate the potential diagnostic role of the oral microbiome during the chronic stage of TBI with a larger number of subjects.

Characteristics of Microbial Distribution in Different Oral Niches of Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC), one of the most common malignant tumors of the head and neck, is closely associated with the presence of oral microbes. However, the microbiomes of different oral niches in OSCC patients and their association with OSCC have not been adequately characterized. In this study, 305 samples were collected from 65 OSCC patients, including tumor tissue, adjacent normal tissue (paracancerous tissue), cancer surface tissue, anatomically matched contralateral normal mucosa, saliva, and tongue coat. 16S ribosomal DNA (16S rDNA) sequencing was used to compare the microbial composition, distribution, and co-occurrence network of different oral niches. The association between the microbiome and the clinical features of OSCC was also characterized. The oral microbiome of OSCC patients showed a regular ecological distribution. Tumor and paracancerous tissues were more microbially diverse than other oral niches. Cancer surface, contralateral normal mucosa, saliva, and tongue coat showed similar microbial compositions, especially the contralateral normal mucosa and saliva. Periodontitis-associated bacteria of the genera Fusobacterium, Prevotella, Porphyromonas, Campylobacter, and Aggregatibacter, and anaerobic bacteria were enriched in tumor samples. The microbiome was highly correlated with tumor clinicopathological features, with several genera (Lautropia, Asteroleplasma, Parvimonas, Peptostreptococcus, Pyramidobacter, Roseburia, and Propionibacterium) demonstrating a relatively high diagnostic power for OSCC metastasis, potentially providing an indicator for the development of OSCC.

Fabrication and Optimization of Essential-Oil-Loaded Nanoemulsion Using Box-Behnken Design against Staphylococos aureus and Staphylococos epidermidis Isolated from Oral Cavity

Oral bacterial infections are fairly common in patients with diabetes mellitus; however, due to limited treatment options, herbal medicines are considered an alternate solution. This study aimed to formulate a stable essential-oil-loaded nanoemulsion for the treatment of oral bacterial infections. Essential oils from edible sources including coriander, clove, cinnamon and cardamom were extracted by hydrodistillation. The response surface methodology was used to optimize the nanoemulsion formulation by applying the Box–Behnken design. The oil concentration, surfactant concentration and stirring speed were three independent factors, and particle size and polydispersity index were two responses. The particle size, polydispersity index and zeta potential of the optimized formulation were 130 mm, 0.222 and −22.9, respectively. The ATR-FTIR analysis revealed that there was no incompatibility between the active ingredients and the excipients. A significant release profile in active ingredients of nanoemulsion, i.e., 88.75% of the cinnamaldehyde and 89.33% of eugenol, was recorded after 24 h. In the ex vivo goat mucosal permeation study, 71.67% of the cinnamaldehyde permeated and that of the eugenol 70.75% from the nanoemulsion. The optimized formulation of the essential-oil-loaded nanoemulsion showed a 9 mm zone of inhibition against Staphylococcus aureus and Staphylococcus epidermidis, whereas in anti-quorum sensing analysis, the optimized nanoemulsion formulation showed an 18 mm zone of inhibition. It was concluded that formulated essential-oil-loaded nanoemulsion can be used against S. epidermidis and S. aureus infections in oral cavity.

A potential oral microbiome signature associated with coronary artery disease in Tunisia

The coronary artery disease (CAD) is a chronic inflammatory disease involving genetic as well as environmental factors. Recent evidence suggests that the oral microbiome has a significant role in triggering atherosclerosis. The present study assessed the oral microbiome composition variation between coronary patients and healthy subjects in order to identify a potential pathogenic signature associated with CAD. We performed metagenomic profiling of salivary microbiomes by 16S ribosomal RNA (rRNA) next-generation sequencing. Oral microbiota profiling was performed for 30 individuals including 20 patients with CAD and ten healthy individuals without carotid plaques or previous stroke or myocardial infarction. We found that oral microbial communities in patients and healthy controls are represented by similar global core oral microbiome. The predominant taxa belonged to Firmicutes (genus Streptococcus, Veillonella, Granulicatella, Selenomonas), Proteobacteria (genus Neisseria, Haemophilus), Actinobacteria (genus Rothia), Bacteroidetes (genus Prevotella, Porphyromonas), and Fusobacteria (genus Fusobacterium, Leptotrichia). More than 60% relative abundance of each sample for both CAD patients and controls is represented by three major genera including Streptococcus (24.97 and 26.33%), Veillonella (21.43 and 19.91%), and Neisseria (14.23 and 15.33%). Using penalized regression analysis, the bacterial genus Eikenella was involved as the major discriminant genus for both status and Syntax score of CAD. We also reported a significant negative correlation between Syntax score and Eikenella abundance in coronary patients' group (Spearman rho = -0.68, P=0.00094). In conclusion, the abundance of Eikenella in oral coronary patient samples compared with controls could be a prominent pathological indicator for the development of CAD.

Oral Microbiota, Its Equilibrium and Implications in the Pathophysiology of Human Diseases: A Systematic Review

Imbalances of the oral microbiota and dysbiosis have traditionally been linked to the occurrence of teeth and oral diseases. However, recent findings indicate that this microbiota exerts relevant influence in systemic health. Dysbiosis of the oral microbiota is implicated in the apparition and progression of cardiovascular, neurodegenerative and other major human diseases. In fact, the oral microbiota are the second most diverse and largely populated microbiota of the human body and its relationships with systemic health, although widely explored, they still lack of proper integration. The purpose of this systematic review is thus to widely examine the implications of oral microbiota in oral, cardiovascular and neurodegenerative diseases to offer integrative and up-to-date interpretations. To achieve that aim, we identified a total of 121 studies curated in PUBMED from the time interval January 2003–April 2022, which after careful screening resulted in 79 studies included. The reviewed scientific literature provides plausible vias of implication of dysbiotic oral microbiota in systemic human diseases, and encourages further research to continue elucidating the highly relevant and still poorly understood implications of this niche microbiota in systemic health. PROSPERO Registration Number: CRD42022299692. This systematic review follows relevant PRISMA guidelines.

Can metagenomics unravel the impact of oral bacteriome in human diseases?

Oral microbial ecosystems are vital in maintaining the health of the oral cavity and the entire body. Oral microbiota is associated with the progression of oral diseases such as dental caries, periodontal diseases, head and neck cancer, and several systemic diseases such as cardiovascular disease, rheumatoid arthritis, adverse pregnancy outcomes, diabetes, lung infection, colorectal cancer, and pancreatic cancer. Buccal mucosa, tongue dorsum, hard palate, saliva, palatine tonsils, throat, keratinized gingiva, supra-gingival plaque, subgingival plaque, dentures, and lips are microbial habitats of the oral cavity. Porphyromonas gingivalis may have a role in the development of periodontal diseases, oral cancer, diabetes, and atherosclerotic disease. Fusobacterium nucleatum showed a higher abundance in periodontal diseases, oral and colon cancer, adverse pregnancy outcomes, diabetes, and rheumatoid arthritis. The higher abundance of Prevotella intermedia is typical in periodontal diseases, rheumatoid arthritis, and adverse pregnancy outcome. S. salivarius displayed higher abundance in both dental caries and OSCC. Oral bacteria may influence systemic diseases through inflammation by releasing pro inflammatory cytokines. Identification of oral bacteria using culture-dependent approaches and next-generation sequencing-based metagenomic approaches is believed to significantly identify the therapeutic targets and non-invasive diagnostic indicators in different human diseases. Oral bacteria in saliva could be exploited as a non-invasive diagnostic indicator for the early detection of oral and systemic disorders. Other therapeutic approaches such as the use of probiotics, green tea polyphenol, cold atmospheric plasma (CAP) therapy, antimicrobial photodynamic therapy, and antimicrobial peptides are used to inhibit the growth of biofilm formation by oral bacteria.