Oral Microbiota Research Articles

Differences Between Vietnamese Living in Germany and German Periodontitis Patients in Periodontal Conditions and Subgingival Microbiota

Introduction and aimsA number of studies have reported ethnic differences in the prevalence and severity of periodontitis. Such discrepancies could be attributed to disparities in periodontal risk factors, as well as variations in the composition of the subgingival microbiota. Given the substantial Vietnamese population residing in the former German Democratic Republic, the present study aimed to compare the clinical and microbial characteristics of periodontitis patients of Vietnamese Asian origin living in Germany with those of German Caucasian periodontitis patients. MethodsA total of 60 patients with a minimum stage II periodontitis diagnosis were included in the study. Of these, 30 were of Vietnamese origin, with an average age of 55 years and a male prevalence of 33.3%. The remaining 30 patients were of German origin, with an average age of 54.5 years and a male prevalence of 40%. The periodontal diagnosis was made in accordance with the recently revised classification of periodontal disease. The pooled subgingival plaque samples were subjected to next-generation sequencing on the MiSeq platform (Illumina). ResultsThe German patients were significantly more likely to be smokers (56.7% vs 13.3%), had significantly higher body mass index (26 vs 22.6 kg/m²), probing depth (4.1 vs 3.6 mm), and clinical attachment loss (5 vs 4.1 mm). In terms of microbiota, the Vietnamese patients exhibited significantly lower beta diversity compared to the German patients, and smokers demonstrated a significantly higher beta diversity compared to nonsmokers. The microbiota of both groups differed most significantly in the relative abundance of Porphyromonas gingivalis (Vietnamese) and Fusobacteriia (German). ConclusionsGerman patients with periodontitis showed more severe periodontal symptoms and more pronounced periodontal risk factors compared to Vietnamese patients. Both patient groups also showed significant differences in the subgingival microbiota. Clinical relevanceCompared to Vietnamese living in Germany, German patients have a higher need for periodontal treatment and at the same time the risk factors of smoking and obesity should be reduced. More research is needed before the differences in oral microbiota between the two groups can lead to individualised therapeutic approaches.

Rodent models for oral microbiome research: considerations and challenges- a mini review.

Rodent models have been commonly employed in oral microbiota research to investigate the relationship between bacteria and oral disease. Nevertheless, to apply the knowledge acquired from studies conducted on rodents to a human context, it is crucial to consider the significant spatial and temporal parallels and differences between the oral microbiota of mice and humans. Initially, we outline the comparative physiology and microbiology of the oral cavity of rodents and humans. Additionally, we highlight the strong correlation between the oral microbiome of rodents and genetic makeup, which is influenced by factors including vendor, husbandry practices, and environmental conditions. All of these factors potentially impact the replicability of studies on rodent microbiota and the resulting conclusions. Next, we direct our attention toward the diversity in the microbiome within mice models of disease and highlight the diversity that may potentially affect the characteristics of diseases and, in turn, alter the ability to replicate research findings and apply them to real-world situations. Furthermore, we explore the practicality of oral microbial models for complex oral microbial diseases in future investigations by examining the concept of gnotobiotic and germ-free mouse models. Finally, we stress the importance of investigating suitable techniques for characterizing and managing genetically modified organisms. Future research should consider these aspects to improve oral microbiome research's translational potential.

The impact of environmental factors on aetiopathogenesis and clinical manifestations of Behçet's syndrome.

Behçet's syndrome (BS) is a rare multisystem vasculitis involving blood vessels of any size. BS aetiology is still unclear to date, and the heterogeneity of clinical expression among ethnics and genders make early diagnosis challenging. However, so far, considerable efforts have been made toward the understanding of BS, leading researchers to agree that the coexistence of some environmental triggers and a genetical susceptibility both underlie BS aetiopathogenesis. In particular, viral agents, oral microbial flora, and mucosal microbiota have been widely explored in this regard, but still no specific microorganism has been definitely linked to the disease aetiology. Likewise, the concept that some environmental factors may play a role in BS clinical presentation has emerged based on the growing evidence that disease severity is usually higher in male patients, and that diet and fatigue may be involved in disease recurrence, especially in mucocutaneous manifestations. Moreover, smoke cessation is acknowledged as a risk factor for oral ulcerations, although the underlying mechanism is still not clear. All those environmental factors play their effects through epigenetic mechanisms. The aim of this review is to discuss the evidence on the role of environmental factors in BS aetiopathogenesis and clinical course.

Differences and Co-variation of oral microbiota in Childhood Caries

Differences and Co-variation of oral microbiota in Childhood Caries

Novel orthodontic adhesives with antibacterial, mineralization and fluorescence properties for enamel demineralization prevention

Enamel demineralization is one of the most common adverse effects of fixed orthodontic treatment, mainly because the appliances affect oral hygiene maintenance, potentially leading to plaque accumulation and oral flora dysbiosis. Adhesives are essential for fixed orthodontic treatment, but excessive adhesives on tooth surfaces might be stained aesthetically and serve as additional sites for plaque accumulation. Some research gaps exist for simultaneously addressing orthodontic enamel demineralization and proper adhesive removal. In this study, novel multifunctional orthodontic adhesives (MFOAs) were developed using amino-silane functionalized zinc oxide quantum dots (AF-ZnOQDS) with fluorescence property, antibacterial agent dimethylaminohexadecyl methacrylate (DMAHDM), and mineralizing material 45S5 bioactive glass (BG-45S5) as the modifiers. The three were incorporated into Transbond XT adhesive at different mass fractions and relevant properties were evaluated in vitro and in vivo. The results indicated that the MFOA-3 with 3 wt% AF-ZnOQDS, 5 wt% DMAHDM, and 7.5 wt% BG-45S5 possessed long-term antibacterial ability, dual-mineralization activity, and strong fluorescence properties. It had clinically acceptable physicochemical properties and good biocompatibility, providing a desirable anti-demineralization effect. Therefore, MFOA-3 provides a new strategy to solve the two major challenges of enamel demineralization and proper removal of adhesives during fixed orthodontics, and thus has great value in clinical application.

Veillonella parvula acts as a pathobiont promoting the biofilm virulence and cariogenicity of Streptococcus mutans in adult severe caries.

Adult severe caries (ASC) brings severe oral dysfunction and treatment difficulties to patients, and yet no clear pathogenic mechanism for it has been found. This study is focused on the composition of dental plaque microbiome profiles in order to identify disease-relevant species and to investigate into their interactions with the S. mutans. Samples of dental plaque were collected for metagenomic analysis. The acidification, aciduricity, oxidative stress tolerance, and gtf (glucosyltransferase) gene expression of S. mutans cocultured with V. parvula which was identified as ASC-related dominant bacterium. The biofilm formation and extracellular exopolysaccharide (EPS) synthesis of dual-strain were analyzed with scanning electron microscopy (SEM), crystal violet (CV) staining, live/dead bacterial staining, and confocal laser scanning microscopy (CLSM). Furthermore, rodent model experiments were performed to validate the in vivo cariogenicity of the dual-species biofilm. The most significantly abundant taxon found associated with ASC was V. parvula. In vitro experiments found that V. parvula can effectively promote S. mutans mature biofilm formation with enhanced acid resistance, hydrogen peroxide detoxicity, and biofilm virulence. Rodent model experiments revealed that V. parvula was incapable of causing disease on its own, but it significantly heightened the biofilm virulence of S. mutans when being co-infected and augmented the progression, quantity, and severity of dental caries. Our findings demonstrated that V. parvula may act as a synergistic pathobiont to modulate the metabolic activity, spatial structure, and pathogenicity of biofilms of S. mutans in the context of ASC.IMPORTANCEAdult severe caries (ASC), as a special type of acute caries, is rarely reported and its worthiness of further study is still in dispute. Yet studies on the etiology of severe caries in adults have not found a clear pathogenic mechanism for it. Knowledge of the oral microbiota is important for the treatment of dental caries. We discovered that the interaction between V. parvula and S. mutans augments the severity of dental caries in vivo, suggesting V. parvula may act as a synergistic pathobiont exacerbating biofilm virulence of S. mutans in ASC. Our findings may improve the understanding of ASC pathogenesis and are likely to provide a basis for planning appropriate therapeutic strategies.

Aphthous stomatitis - computational biology suggests external biotic stimulus and immunogenic cell death involved

BackgroundThe exact cause of recurrent aphthous stomatitis is still unknown, making it a challenge to develop effective treatments. This study employs computational biology to investigate the molecular basis of recurrent aphthous stomatitis, aiming to identify the nature of the stimuli triggering these ulcers and the type of cell death involved.MethodsTo understand the molecular underpinnings of recurrent aphthous stomatitis, we used the Génie tool for gene identification, targeting those associated with cell death in recurrent aphthous stomatitis. The ToppGene Suite was employed for functional enrichment analysis. We also used Reactome and InteractiVenn for protein integration and prioritization against a PANoptosis gene list, enabling the construction of a protein-protein interaction network to pinpoint key proteins in recurrent aphthous stomatitis pathogenesis.ResultsThe study’s computational approach identified 1,375 protein-coding genes linked to recurrent aphthous stomatitis. Critical among these were proteins responsive to bacterial stimuli, especially high mobility group protein B1 (HMGB1), toll-like receptor 2 (TLR2), and toll-like receptor 4 (TLR4). The enrichment analysis suggested an external biotic factor, likely bacterial, as a triggering agent in recurrent aphthous stomatitis. The protein interaction network highlighted the roles of tumor necrosis factor (TNF), NF-kappa-B essential modulator (IKBKG), and tumor necrosis factor receptor superfamily member 1A (TNFRSF1A), indicating an immunogenic cell death mechanism, potentially PANoptosis, in recurrent aphthous stomatitis.ConclusionThe findings propose that bacterial stimuli could trigger recurrent aphthous stomatitis through a PANoptosis-related cell death pathway. This new understanding of recurrent aphthous stomatitis pathogenesis underscores the significance of oral microbiota in the condition. Future experimental validation and therapeutic strategy development based on these findings are necessary.

Some oral microbiota in complete cleft infants in comparison with normal infants.

To compare caries-related microorganisms and candida in complete cleft infants with normal palate infants. The case-control study was conducted from April 2021 to January 2022 at the College of Dentistry, University of Baghdad, Baghdad, Iraq, and comprised infants with age ranging from 1 day to 4 months. They were divided into complete cleft group A and control group B. Group A was subdivided into those with class III Veau's palatal classification, and the rest with class IV Veau's palatal classification. Samples were taken using oral swab which were subjected to colony morphology, gram staining and biochemical testing. Data was analysed using SPSS 21. Of the 52 subjects, 26(50%) were in each of the 2 groups. The subgroups of group A had 13(50%) patients each. The counting and colonisation of streptococcus mutans, lactobacilli and candida albicans were significantly higher in group A than in group B (p<0.05). The difference between the subgroups of group A was not significant (p>0.05). Infants with cleft palate were more susceptible to dental caries and oral infection than those with normal palate.

Antibacterial periodontal ligament stem cells enhance periodontal regeneration and regulate the oral microbiome

BackgroundThe transplantation of periodontal ligament stem cells (PDLSCs) has been shown to enhance periodontal regeneration in animal models and clinical trials. However, it is not known whether PDLSCs are antibacterial and whether this affects oral microbiota and periodontal regeneration.MethodsWe isolated human PDLSCs from periodontal ligament of extracted teeth. Rats’ periodontal fenestration defects were prepared, and treated with PDLSC injections (Cell group), using saline injections (Saline group) as the control. The oral microbiota was explored by 16 S rDNA sequencing and compared with that before surgery (PRE group). The antibacterial property of PDLSCs and its underlying mechanism were tested in vitro.ResultsMicrobiome analyses reveal a decreased biodiversity, a changed community structure, and downregulated community functions of the oral microbiome in the Saline group. PDLSCs injections enhance periodontal regeneration, reverse the decrease in diversity, and increase the abundance of non-pathogenic bacterial Bifidobacterium sp. and Lactobacillus sp., making the oral microbiome similar to that of the PRE group. In vitro, PDLSCs inhibit the growth of Staphylococcus aureus, Escherichia coli, and Fusobacterium nucleatum. The main mechanism of action is postulated to involve production of the cationic antimicrobial peptide LL-37.ConclusionsOur findings reveal that PDLSC injections enhance periodontal regeneration and regulate the oral microbiome to foster an oral cavity microenvironment conducive to symbiotic microbiota associated with health.

The Association of the Oral Microbiota with Cognitive Functioning in Adolescence.

Background: A growing body of research supports the role of the microbial communities residing in the digestive system in the host's cognitive functioning. Most of these studies have been focused on the gut microbiome and its association with clinical phenotypes in middle-aged and older adults. There is an insufficiency of population-based research exploring the association of normative cognitive functioning with the microbiome particularly with the oral microbiota. Methods: In this study, using metagenomics and metabolomics, we characterized the salivary microbiome diversity in a sample of 51 males of Hispanic and African American origin aged 12-18 years and explored the associations between the microbiome and the youths' cognitive performance captured with the Kaufman Assessment Battery for Children II (KABC-II). Results: Several bacterial species of the oral microbiota and related metabolic pathways were associated with cognitive function. In particular, we found negative associations between indicators of general intelligence and the relative abundance of Bacteroidetes and Lachnospiraceae and positive associations with Bifidobacteriaceae and Prevotella histicola sp. Among metabolic pathways, the super pathways related to bacterial cell division and GABA metabolism were linked to cognitive function. Conclusions: The results of our work are consistent with the literature reporting on the association between microbiota and cognitive function and support further population work to elucidate the potential for a healthy oral microbiome to improve cognitive health.

Mechanistic Insights on Microbiota-Mediated Development and Progression of Esophageal Cancer

Esophageal cancer (EC) is one of the most common malignant tumors worldwide, and its two major types, esophageal adenocarcinoma (EAC) and esophageal squamous cell carcinoma (ESCC), present a severe global public health problem with an increasing incidence and mortality. Established risk factors include smoking, alcohol consumption, and dietary habits, but recent research has highlighted the substantial role of oral microbiota in EC pathogenesis. This review explores the intricate relationship between the microbiome and esophageal carcinogenesis, focusing on the following eight significant mechanisms: chronic inflammation, microbial dysbiosis, production of carcinogenic metabolites, direct interaction with epithelial cells, epigenetic modifications, interaction with gastroesophageal reflux disease (GERD), metabolic changes, and angiogenesis. Certain harmful bacteria, such as Porphyromonas gingivalis and Fusobacterium nucleatum, are specifically implicated in sustaining irritation and tumor progression through pathways including NF-κB and NLRP3 inflammasome. Additionally, the review explores how microbial byproducts, including short-chain fatty acids (SCFAs) and reactive oxygen species (ROS), contribute to DNA harm and disease advancement. Furthermore, the impact of reflux on microbiota composition and its role in esophageal carcinogenesis is evaluated. By combining epidemiological data with mechanistic understanding, this review underscores the potential to target the microbiota–immune system interplay for novel therapeutic and diagnostic strategies to prevent and treat esophageal cancer.

Oral Microbiome and Subsequent Risk of Head and Neck Squamous Cell Cancer

The oral microbiota may be involved in development of head and neck squamous cell cancer (HNSCC), yet current evidence is largely limited to bacterial 16S amplicon sequencing or small retrospective case-control studies. To test whether oral bacterial and fungal microbiomes are associated with subsequent risk of HNSCC development. Prospective nested case-control study among participants providing oral samples in 3 epidemiological cohorts, the American Cancer Society Cancer Prevention Study II Nutrition Cohort, the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, and the Southern Community Cohort Study. Two hundred thirty-six patients who prospectively developed HNSCC were identified during a mean (SD) of 5.1 (3.6) years of follow-up. Control participants who remained HNSCC free were selected by 2:1 frequency matching on cohort, age, sex, race and ethnicity, and time since oral sample collection. Data analysis was conducted in 2023. Characterization of the oral bacterial microbiome using whole-genome shotgun sequencing and the oral fungal microbiome using internal transcribed spacer sequencing. Association of bacterial and fungal taxa with HNSCC was assessed by analysis of compositions of microbiomes with bias correction. Association with red and orange oral pathogen complexes was tested by logistic regression. A microbial risk score for HNSCC risk was calculated from risk-associated microbiota. The primary outcome was HNSCC incidence. The study included 236 HNSCC case participants with a mean (SD) age of 60.9 (9.5) years and 24.6% women during a mean of 5.1 (3.6) years of follow-up, and 485 matched control participants. Overall microbiome diversity at baseline was not related to subsequent HNSCC risk; however 13 oral bacterial species were found to be differentially associated with development of HNSCC. The species included the newly identified Prevotella salivae, Streptococcus sanguinis, and Leptotrichia species, as well as several species belonging to beta and gamma Proteobacteria. The red/orange periodontal pathogen complex was moderately associated with HNSCC risk (odds ratio, 1.06 per 1 SD; 95% CI, 1.00-1.12). A 1-SD increase in microbial risk score (created based on 22 bacteria) was associated with a 50% increase in HNSCC risk (multivariate odds ratio, 1.50; 95% CI, 1.21-1.85). No fungal taxa associated with HNSCC risk were identified. This case-control study yielded compelling evidence that oral bacteria are a risk factor for HNSCC development. The identified bacteria and bacterial complexes hold promise, along with other risk factors, to identify high-risk individuals for personalized prevention of HNSCC.

Exploring microbial diversity and biosynthetic potential in zoo and wildlife animal microbiomes

Understanding human, animal, and environmental microbiota is essential for advancing global health and combating antimicrobial resistance (AMR). We investigate the oral and gut microbiota of 48 animal species in captivity, comparing them to those of wildlife animals. Specifically, we characterize the microbiota composition, metabolic pathways, AMR genes, and biosynthetic gene clusters (BGCs) encoding the production of specialized metabolites. Our results reveal a high diversity of microbiota, with 585 novel species-level genome bins (SGBs) and 484 complete BGCs identified. Functional gene analysis of microbiomes shows diet-dependent variations. Furthermore, by comparing our findings to wildlife-derived microbiomes, we observe the impact of captivity on the animal microbiome, including examples of converging microbiome compositions. Importantly, our study identifies AMR genes against commonly used veterinary antibiotics, as well as resistance to vancomycin, a critical antibiotic in human medicine. These findings underscore the importance of the ‘One Health’ approach and the potential for zoonotic transmission of pathogenic bacteria and AMR. Overall, our study contributes to a better understanding of the complexity of the animal microbiome and highlights its BGC diversity relevant to the discovery of novel antimicrobial compounds.

Altered oral microbiota of drug-resistant organism carriers exhibit impaired gram-negative pathogen inhibition.

The oral microbiome has been understudied as a reservoir for clinical pathogens, including drug-resistant strains. Understanding how alterations in microbiome functioning render this site vulnerable to colonization is essential, as multidrug-resistant organisms (MDRO) carriage is a major risk factor for developing serious infections. To advance our knowledge of oral MDRO carriage and protection against pathogen colonization conferred by native microbiota, we examined microbiomes from individuals colonized by MDROs (n=33) and non-colonized age-matched controls (n=30). Shotgun metagenomic analyses of oral swabs from study participants revealed significant differences in microbial communities with depletion of Streptococcus spp. among those colonized by multidrug-resistant gram-negative bacilli (RGNB), compared to non-carriers. We utilized metagenomic sequencing to characterize the oral resistome and find antimicrobial resistance genes are present in higher abundance among RNGB carriers versus non-carriers. High-throughput co-culture screening revealed oral bacteria isolated from MDRO non-carriers demonstrate greater inhibition of gram-negative pathogens, compared to isolates from carriers. Moreover, biosynthetic gene clusters from streptococci are found in higher abundance from non-carrier microbiomes, compared to RGNB carrier microbiomes. Bioactivity-guided fractionation of extracts from Streptococcus isolate SID2657 demonstrated evidence of strong E. coli and A. baumannii inhibition in a murine model of infection. Together, this provides evidence that oral microbiota shape this dynamic microbial community and may serve as an untapped source for much-needed antimicrobial small-molecules.

Swarming bacteria exhibit developmental phase transitions to establish scattered colonies in new regions.

The bacterial Type 9 Secretion System (T9SS) is essential for the development of periodontal diseases and Bacteroidetes gliding motility. T9SS-driven motile bacteria, abundant within the human oral microbiota, transport non-motile oral microbes and bacteriophages as cargo, shaping the spatial structure of polymicrobial communities. However, the physical rules governing the dispersal of T9SS-driven bacterial swarms are barely understood. Here, we collected time-lapse images, under anaerobic conditions, of developing swarms of a T9SS-driven microbe common to the human oral microbiota. Tracking of swarms revealed that small peripheral flares emerging from a colony develop structures that resemble fireworks displaying a chrysanthemum effect and flower-like patterns that convert to wave-like patterns and which further evolve into scattered microcolonies. Particle-image velocimetry showed density-dependent phase transitions and initial vorticity within these emerging patterns. Numerical simulations demonstrate that these patterns arise due to changes in swarm speed and alignment strength. Our data reveal a strategy used by an anaerobic swarming bacterium to control swarm behavior, resulting in scattered microcolonies distant from the mother colony, thus reducing competition for resources among colony members. This might ensure species survival even if conditions change drastically in one location of the human oral cavity.

Dietary Determinants of Metabolic and Gut Microbial Health in Patients with Inflammatory Bowel Disease.

Background: Diet has been linked to gut dysbiosis and the onset, course, and response to treatment of patients with IBD and metabolic disease. Methods: This single-centre prospective case-control study investigated the relationship between dietary intake, metabolic profile, and stool microbial composition in 57 individuals with IBD in clinical remission and 24 healthy individuals (HC). Participants' baseline anthropometric measurements, serum metabolic parameters, lipid profiles, and oral and stool samples for microbiota testing were collected. Their dietary intake and physical activity were documented. A partially corrected correlation was performed to examine the associations between variables and p-values adjusted for multiple comparisons using the Benjamini-Hochberg equation (adj-p). Results: In participants with IBD, the intake of saturated fat correlated positively, and the intake of dietary fibre correlated negatively with anthropometric indices (saturated fat and BMI: r = 0.37, adj-p = 0.04, fibre and BMI: r = -0.45, adj-p = 0.01). Higher anthropometric indices were associated with poorer glucose control and a less favourable serum lipid profile (BMI and insulin: r = 0.48, p < 0.01, WHR and triglycerides: r = 0.57, p < 0.01). The stool microbiota of participants in the IBD group was less diverse and more similar to their oral microbiota than was observed in the HC group (Mann-Whitney U test p = 0.03). Within the IBD group, a higher intake of added sugar and processed meat and a higher serum insulin level was associated with lower stool microbial alpha diversity (processed meat intake and Shannon's diversity: r = -0.43, adj-p = 0.02; added sugar and Shannon's diversity: r = -0.39, adj-p = 0.03; insulin and Shannon's diversity: r = -0.45, adj-p = 0.02). Neither the dietary intake nor stool microbial composition correlated with the risk of disease flaring. Conclusions: Our findings suggest that dietary intake is associated with the metabolic health and gut microbial composition of IBD patients.

The Oral Microbiome of Peri-Implant Health and Disease: A Narrative Review.

Peri-implantitis disease has increased significantly over the last years, resulting in increased failure of implants. Many factors may play a role in implant complications and failure, including ones related to the oral microbiota. This literature review aims to summarize the current knowledge of microbiome of implants in health and disease, focusing not only on the presence/absence of specific microbiota or on their relative abundance, but also on their phenotypic expression and their complex relationships with the host. The authors examined the MEDLINE database and identified key topics about peri-implant oral microbiome in health and disease. The peri-implant microbiome differs from that of the tooth, both in health and disease, as they are structurally and chemically different. The adhesion and formation of the peri-implant biofilm can be affected by the surface energy, topography, wettability, and electrochemical charges of the implant surface. In addition, the morphogenesis of the tissues surrounding the dental implant also differs from the tooth, making the dental implant more susceptible to bacterial infection. This interplay between the microbiome and the host immune system in peri-implant infections still needs to be elucidated.

Oral Microbiota and the Risk of Gastrointestinal Cancers-A Narrative Literature Review.

The human body is colonized by trillions of microorganisms in a symbiotic relationship. The oral cavity represents one of the most abundant microbial habitats in our body. Advances in sequencing techniques provide a more detailed understanding of the oral microbiota and how imbalances between bacteria, the phenomenon of dysbiosis, can affect not only the development of dental caries or inflammation within the oral cavity but also systemic diseases and cancers in distant locations. This narrative review evaluates the relationship between oral microbiota and its impact on gastrointestinal cancers. Using the keywords "oral microbiota 'AND' gastrointestinal cancers", the PubMed Web of Science and Scopus databases were searched for articles published between 2014 and 2024. Based on the review, the relationship between oral microbiota and oral, esophageal, gastric, colorectal, hepatocellular, and pancreatic cancers was described. Potential oncogenic mechanisms exploited by the microbiota such as the production of pro-inflammatory cytokines, induction of abnormal immune responses, and disruption of cell metabolic pathways were assessed. Further research and a thorough understanding of the impact of the oral microbiota on the development of cancers of the gastrointestinal tract may play a key role in their prevention, diagnosis, and treatment in the future.

Balancing the Oral-Gut-Brain Axis with Diet.

Background: The oral microbiota is the second largest microbial community in humans. It contributes considerably to microbial diversity and health effects, much like the gut microbiota. Despite physical and chemical barriers separating the oral cavity from the gastrointestinal tract, bidirectional microbial transmission occurs between the two regions, influencing overall host health. Method: This review explores the intricate interplay of the oral-gut-brain axis, highlighting the pivotal role of the oral microbiota in systemic health and ageing, and how it can be influenced by diet. Results: Recent research suggests a relationship between oral diseases, such as periodontitis, and gastrointestinal problems, highlighting the broader significance of the oral-gut axis in systemic diseases, as well as the oral-gut-brain axis in neurological disorders and mental health. Diet influences microbial diversity in the oral cavity and the gut. While certain diets/dietary components improve both gut and oral health, others, such as fermentable carbohydrates, can promote oral pathogens while boosting gut health. Conclusions: Understanding these dynamics is key for promoting a healthy oral-gut-brain axis through dietary interventions that support microbial diversity and mitigate age-related health risks.

Analysis of Oral Microbiota in Elderly Thai Patients with Alzheimer's Disease and Mild Cognitive Impairment.

Alzheimer's disease (AD) is a neurodegenerative disease that predominantly affects the older adult population. Neuroinflammation may be triggered by the migration of oral microbiota composition changes from the oral cavity to the brain. However, the relationship between oral microbiota composition and neurodegenerative diseases, such as AD, remains poorly understood. Therefore, we conducted a comprehensive comparison of the relative abundance and diversity of bacterial taxa present in saliva among older adults diagnosed with AD, those with mild cognitive impairment (MCI), and healthy controls. Saliva samples and clinical data were collected from 10 AD patients, 46 MCI patients, and 44 healthy older adults. AD patients had lower Clinical Dementia Rating, Montreal Cognitive Assessment, and Mini-mental Status Examination scores, and induced microbial diversity, than the MCI and control groups. Moreover, AD patients exhibited significantly higher levels of Fusobacteriota and Peptostreptococcaceae and lower levels of Veillonella than the MCI and control groups. In conclusion, a high abundance of Fusobacteria at various levels (i.e., phylum, class, family, and genus levels) may serve as a biomarker for AD. The analysis of oral microbiota dysbiosis biomarkers in older adults may be valuable for identifying individuals at risk for AD.