Drinking alcohol is associated with variation in the human oral microbiome in a large study of American adults

Short-term microplastic exposure: A double whammy to lung metabolism and fecal microflora in diabetic SD rats

Diabetes has become a global health crisis, affecting over 800 million people, with serious complications such as vascular and neurological damage. While diabetes management has been extensively studied, the impact of environmental pollutants, particularly microplastics (PS), on diabetic health remains poorly understood. PS, defined as plastic particles smaller than 5 mm, are pervasive and can enter the body through inhalation or ingestion, posing potential risks. However, the effects of PS exposure, particularly in diabetes, have not been adequately explored. Most studies focus on high-concentration, long-term exposure, which does not reflect typical human exposure levels. This study investigates the effects of short-term PS exposure on diabetic SD rats, using histological, apoptotic, and omics techniques, including metabolomics, lipidomics, and 16S rDNA sequencing. Our results show that short-term PS exposure exacerbates lung and intestinal damage in diabetic rats, with significant alterations in the gut microbiome. We also observed correlations between differential metabolites and microbiota changes. These findings provide novel evidence that short-term PS exposure, at concentrations reflecting daily contact, worsens metabolic dysfunction and intestinal dysbiosis in diabetes. This study emphasizes the need to consider environmental pollutants in diabetes management and highlights potential strategies for prevention and therapy.

Exploring ethanol's toxicity in the oral submucosa: chronic exposure versus abstinence in C57BL/6 mice

Alcohol consumption is a recognised risk factor for the development of precancerous lesions in the oral cavity. This study investigates the effects of chronic ethanol exposure on inflammation and fibrosis in mice.Eighteen C57BL/6 mice were divided into three groups: Group I received only drinking water, while Groups II and III were exposed to 25% ethanol ad libitum for 14 weeks. Group II mice were sacrificed at the end of the 14th week, whereas Group III underwent a 4-week abstinence period before sacrifice. Gene expression related to inflammation and fibrosis, along with histopathological changes in submucosal tissue, was analysed.Chronic ethanol exposure significantly upregulated MAPK signalling markers, as well as inflammatory and fibrotic markers, in submucosal tissue. In Group III, inflammatory markers such as NF-κB, p65, NLRP3, and caspase-1 partially returned to normal levels after abstinence, whereas fibrotic markers, particularly MMP-9, remained elevated. Histopathological analysis of oral submucosa revealed epithelial atrophy and extracellular matrix accumulation in ethanol-exposed mice.These findings suggest that 14 weeks of ethanol exposure induces persistent epithelial damage, inflammation, and fibrosis in the oral submucosa, with incomplete reversal after 4 weeks of abstinence. This underscores the lasting impact of alcohol on oral tissue, even after cessation.

Nitrate ameliorates alcohol-induced cognitive impairment via oral microbiota

Alcohol use is associated with cognitive impairment and dysregulated inflammation. Oral nitrate may benefit cognitive impairment in aging through altering the oral microbiota. Similarly, the beneficial effects of nitrate on alcohol-induced cognitive decline and the roles of the oral microbiota merit investigation. Here we found that nitrate supplementation effectively mitigated cognitive impairment induced by chronic alcohol exposure in mice, reducing both systemic and neuroinflammation. Furthermore, nitrate restored the dysbiosis of the oral microbiota caused by alcohol consumption. Notably, removing the oral microbiota led to a subsequent loss of the beneficial effects of nitrate. Oral microbiota from donor alcohol use disordered humans who had been taking the nitrate intervention were transplanted into germ-free mice which then showed increased cognitive function and reduced neuroinflammation. Finally, we examined 63 alcohol drinkers with varying levels of cognitive impairment and found that lower concentrations of nitrate metabolism-related bacteria were associated with higher cognitive impairment and lower nitrate levels in plasma. These findings highlight the protective role of nitrate against alcohol-induced cognition impairment and neuroinflammation and suggest that the oral microbiota associated with nitrate metabolism and brain function may form part of a "microbiota-mouth-brain axis".

Alcohol exposure alters the diversity and composition of oral microbiome

Introduction

Alcohol exposure has been shown to have complex, and sometimes paradoxical, associations with various serious diseases. Currently, there is no knowledge about the effects of alcohol exposure on the dynamics of oral microbial communities.

Objective

The study aims to investigate the effects of chronic alcohol consumption on the diversity and composition dynamics of the rat oral microbiota using 16S rRNA gene amplicon sequencing.

Methods

In our study, there were 2 groups, including a control group (C group) and an alcohol group (A group), with 10 rats in every group. For ten weeks, rats in the A group were treated with alcohol intragastrically every day, whereas rats in the C group got water. After 10 weeks, serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured. Oral swabs were taken from both groups, and total DNA was extracted for high-throughput sequencing of the 16S rRNA gene.

Results

According to the results obtained from our study, significant differences were observed in the relative abundances of microbial communities. Alpha diversity measures were statistically significantly higher (P < 0.05) in the A group compared to the C group. At the genus level, alcohol exposure altered the relative abundance of several microbes, including increased relative abundance of unidentified_Chloroplast, Acinetobacter, Vibrio, Romboutsia, Pseudoalteromonas, Aeromonas, Ralstonia, Turicibacter, Shewanella, and Bacteroides. Conversely, Haemophilus and Streptococcus were significantly less abundant in the A group.

Conclusion

Alcohol exposure was associated with the diversity and composition of the oral microbiome. These findings contribute to our understanding of the potential role of oral bacteria in alcohol-related oral and systemic diseases, providing foundational work for future prevention and intervention studies.

The Oral-Gut Microbiome-Brain Axis in Cognition

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline and neuronal loss, affecting millions worldwide. Emerging evidence highlights the oral microbiome-a complex ecosystem of bacteria, fungi, viruses, and protozoa as a significant factor in cognitive health. Dysbiosis of the oral microbiome contributes to systemic inflammation, disrupts the blood-brain barrier, and promotes neuroinflammation, processes increasingly implicated in the pathogenesis of AD. This review examines the mechanisms linking oral microbiome dysbiosis to cognitive decline through the oral-brain and oral-gut-brain axis. These interconnected pathways enable bidirectional communication between the oral cavity, gut, and brain via neural, immune, and endocrine signaling. Oral pathogens, such as Porphyromonas gingivalis, along with virulence factors, including lipopolysaccharides (LPS) and gingipains, contribute to neuroinflammation, while metabolic byproducts, such as short-chain fatty acids (SCFAs) and peptidoglycans, further exacerbate systemic immune activation. Additionally, this review explores the influence of external factors, including diet, pH balance, medication use, smoking, alcohol consumption, and oral hygiene, on oral microbial diversity and stability, highlighting their role in shaping cognitive outcomes. The dynamic interplay between the oral and gut microbiomes reinforces the importance of microbial homeostasis in preserving systemic and neurological health. The interventions, including probiotics, prebiotics, and dietary modifications, offer promising strategies to support cognitive function and reduce the risk of neurodegenerative diseases, such as AD, by maintaining a diverse microbiome. Future longitudinal research is needed to identify the long-term impact of oral microbiome dysbiosis on cognition.

The current status and influencing factors of oral frailty in elderly populations: A scoping review

AIM

In order to serve as a reference for future studies on oral frailty interventions, this scoping review aims to provide an analysis of the factors influencing oral frailty in elderly group.

DESIGN

A scoping review based on the principles of participants, concept and context (PCC) and a theoretical framework of the Health Ecology Model (HEM).

REVIEW METHODS

Based on the principle of PCC, this study reviews the prevalence and influencing factors of oral frailty.

DATA SOURCES

A systematic search was conducted across eight Chinese and English databases with time ranged from their foundation to March 10, 2024, using a combination of subject terms and free words. For the English database Web of Science, the search formula was: #1: TI = (aged OR elder OR elderly people), #2: TI = (Oral frail* OR Oral frailty OR oral weakness), #3: #1 AND #2. And manual searches were conducted using literature tracing methods for retrospective queries.

RESULTS

A total of 25 papers were included, reporting a prevalence of oral frailty ranging from 9.5% to 59.2%. These papers identified 34 influencing factors categorized into four levels: individual characteristics level (such as age, gender, number of teeth, number of dentures, masticatory ability, swallowing ability, oral health, tongue pressure, dry mouth, periodontitis, medications, cognitive ability, physical frailty, nutrition, type of chronic diseases, cardiovascular disease, diabetes, cancer history, hemoglobin, albumin, BMI, Cystatin C), psycho-behavioral and lifestyle level (including depression, sleep quality, dietary habits, physical activity, smoking, alcohol, and oral health-related self-efficacy), interpersonal network level (social support, social isolation), and work and living level (income status, educational level, and type of residence).

CONCLUSIONS

The high prevalence of oral frailty in the elderly group worldwide is influenced by 34 factors, highlighting the importance of considering the synergistic effects of multiple influences. Meanwhile, the OFI-6 and OFI-8 are commonly used assessment tools for oral frailty research in the elderly, and each plays an important role. OFI-8 is a self-reported and subjective assessment scale that does not require specialized oral examination tool compared to OFI-6. As a result, it is better suited for rapid screening in community and outpatient settings than the OFI-6.

IMPACT

Generalizing the influencing factors of oral frailty facilitates a deeper understanding of its pathogenesis, enables the identification of high-risk groups, and provides a theoretical foundation for developing interventions aimed at preventing and mitigating oral frailty among the elderly.

PATIENT OR PUBLIC CONTRIBUTION

Not applicable.

Association between adjustable dietary factors and periodontitis: NHANES 2009-2014 and Mendelian randomization

BACKGROUND

Periodontitis is the major cause of tooth loss in adults and one of the most common non-communicable diseases. Clinically, periodontitis impairs oral health and associated with various systemic diseases. Maintaining a healthy diet is considered risk reduction of periodontitis. To explore the causal effect between dietary data and periodontitis by Mendelian randomization (MR) analyses.

METHODS

A total of 11,704 participants and 21 dietary variables from the NHANES were in random forest to rank the importance in predicting periodontitis. Data were from the genome wide association studies (GWASs) database to estimate causal relationships between diet data and periodontitis. Two-sample MR analyses were conducted by using the inverse-variance weighted (IVW) method.

RESULTS

The MR showed alcohol consumption and sugars intake increased the risk of chronic periodontitis with odds ratio (OR) 2.768 (95% CI: 1.03e + 00-7.42e + 00) and 2.123 (95% CI: 1.06e + 00-4.26e + 00) respectively. Vitamins and minerals, including folic acid and folate, magnesium, vitamin A, vitamin E, vitamin C, calcium, vitamin D and zinc, were not causally associated with chronic periodontitis. Alcohol consumption greater than 2.5 drinks per day and sugar intake more than 4.88 g increased the risk of periodontitis, with a calculated relative risk of 1.33 and 1.61, respectively.

CONCLUSION

It is suggested to drink alcohol less than 2.5 drinks/day and consume sugar less than 4.88 g/day to avoid alcohol and sugar consumption promoting the development of periodontitis. Establishing a dietary pattern conducive to periodontal health may be the focus of further clinical research.

The oral microbiota and its relationship to dental calculus and caries

OBJECTIVES

In this review, we provide an overview of the composition of the microbiota associated with these two dental pathologies, caries and tartar, highlighting the microbial profiles associated with each pathology.

DESIGN

This literature review was carried out by a manual search of two electronic databases, PubMed and Web of Science (WOS), using specific keywords to the two oral pathologies dental caries and calculus.

RESULTS

The oral microbial community is known for its complexity, and comprises hundreds of species of different micro-organisms. Many of them, under the influence of endogenous and exogenous factors, can play a role in the onset and development of oral pathologies. Analysis of the microbial profiles of caries and dental calculus revealed that Streptococcus mutans and Lactobacillus species are abundant in the oral microbiota associated with caries whereas their presence is less reported in dental calculus. However, the three pathogens known as the "red complex", namely Porphyromonas, Tannarella and Treponema, which are associated with the development of periodontal pathology, are strongly present in the dental calculus microbiome.

CONCLUSION

The microbiota composition associated with dental caries and calculus highlights specific microbial signatures for each of the two oral pathologies, underscoring their differences and microbiological complexity, while the possible relationship between the formation of dental calculus and the development of caries remains unclear.

Comparative Analysis of Oral Prevotella intermedia, Tannerella forsythia, Streptococcus sanguinis, and Streptococcus mutans in Patients with Esophageal Squamous Cell Carcinoma and Healthy Controls in Mthatha, South Africa

The microbiome plays a crucial role in cancer development, influencing fundamental processes such as cell proliferation, apoptosis, immune system regulation, and host metabolism. Recent studies have highlighted a possible relationship between esophageal cancer and the oral microbiota, making oral microflora a possible risk factor. The bacteria Prevotella intermedia, Tannerella forsythia, Streptococcus sanguinis, and Streptococcus mutans, implicated in various oral pathologies, were of interest in this study, which was initiated to examine their potential role in the etiology of esophageal squamous cell carcinoma (ESCC). To achieve this, a case-control design was used, with whole saliva samples collected from 24 healthy controls and 24 patients with esophageal squamous cell carcinoma. DNA was then extracted, and real-time PCR was performed to quantify the presence of the targeted bacteria in both groups. The results showed that all the bacteria studied were present in the saliva of both patients with ESCC and healthy controls. However, expression levels were significantly higher in patients with ESCC. Specifically, a marked increase in the presence of P. intermedia, T. forsythia, S. sanguinis, and S. mutans was observed in the patients with cancer compared to the healthy controls. In short, this study highlights a significant imbalance in the microbial flora, with an increased abundance of selected bacteria in patients with ESCC. The monitoring of these bacteria could thus be exploited to track patients who are at risk. Their integration into diagnostic and therapeutic strategies would offer new prospects for the early diagnosis and improved prognosis of patients at risk of ESCC.

Intra-tumoral bacteria in head and neck cancer: holistic integrative insight

Intra-tumoral bacteria are pivotal in the initiation and progression of head and neck squamous cell carcinoma (HNSCC), exerting a significant influence on tumor cell biology, immune responses, and the tumor microenvironment (TME). Different types and distribution of bacteria threaten the balance of metabolism and the immune environment of tumor cells. Taking advantage of this disrupted homeostasis, intra-tumoral bacteria stimulate the secretion of metabolites or influence specific immune cell types to produce inflammatory or chemokines, thereby influencing the anti-tumor immune response while regulating the level of inflammation and immunosuppression within the TME. Some intra-tumoral bacteria are used as diagnostic and prognostic markers in clinical practice. Based on the unique characteristics of bacteria, the use of engineered bacteria and outer membrane vesicles for drug delivery and biological intervention is a promising new therapeutic strategy. The presence of intra-tumoral bacteria also makes chemoradiotherapy tolerable, resulting in a poor treatment effect. However, due to the immune-related complexity of intra-tumoral bacteria, there may be unexpected effects in immunotherapy. In this review the patterns of intra-tumoral bacteria involvement in HNSCC are discussed, elucidating the dual roles, while exploring the relevance to anti-tumor immune responses in the clinical context and the prospects and limitations of the use of bacteria in targeted therapy.

Role of Fungi in Tumorigenesis: Promises and Challenges

The mycobiome plays a key role in the host immune responses in homeostasis and inflammation. Recent studies suggest that an imbalance in the gut's fungi contributes to chronic, noninfectious diseases such as obesity, metabolic disorders, and cancers. Pathogenic fungi can colonize specific organs, and the gut mycobiome has been linked to the development and progression of various cancers, including colorectal, breast, head and neck, and pancreatic cancers. Some fungal species can promote tumorigenesis by triggering the complement system. However, in immunocompromised patients, fungi can also inhibit this activation and establish life-threatening infections. Interestingly, the interaction of the fungi and bacteria can also induce unique host immune responses. Recent breakthroughs and advancements in high-throughput sequencing of the gut and tumor mycobiomes are highlighting novel diagnostic and therapeutic opportunities for cancer. We discuss the latest developments in the field of cancer and the mycobiome and the potential benefits and challenges of antifungal therapies.

Periodontal disease and cirrhosis: current concepts and future prospects

Periodontal diseases are prevalent among the general population and are associated with several systemic conditions, such as chronic kidney disease and type 2 diabetes mellitus. Chronic liver disease and cirrhosis have also been linked with periodontal disease, an association with complex underlying mechanisms, and with potential prognostic implications. Multiple factors can explain this relevant association, including nutritional factors, alcohol consumption, disruption of the oral-gut-liver axis and associated dysbiosis. Additionally, patients with liver disease have been observed to exhibit poorer oral hygiene practices compared with the general population, potentially predisposing them to the development of periodontal disease. Therefore, it is recommended that all patients with liver disease undergo screening and subsequent treatment for periodontal disease. Treatment of periodontal disease in patients with cirrhosis may help reduce liver-derived inflammatory damage, with recent research indicating a potential benefit in terms of reduced mortality. However, further studies on periodontal disease treatment in patients with liver disease are still warranted to determine optimal management strategies. This narrative review describes current concepts on the association between periodontal disease and chronic liver disease.

The Hygienic Significance of Microbiota and Probiotics for Human Wellbeing

The human body can be viewed as a combination of ecological niches inhabited by trillions of bacteria, viruses, fungi, and parasites, all united by the microbiota concept. Human health largely depends on the nature of these relationships and how they are built and maintained. However, personal hygiene practices have historically been focused on the wholesale elimination of pathogens and "hygiene-challenging microorganisms" without considering the collateral damage to beneficial and commensal species. The microbiota can vary significantly in terms of the qualitative and quantitative composition both between different people and within one person during life, and the influence of various environmental factors, including age, nutrition, bad habits, genetic factors, physical activity, medication, and hygienic practices, facilitates these changes. Disturbance of the microbiota is a predisposing factor for the development of diseases and also greatly influences the course and severity of potential complications. Therefore, studying the composition of the microbiota of the different body systems and its appropriate correction is an urgent problem in the modern world. The application of personal hygiene products or probiotics must not compromise health through disruption of the healthy microbiota. Where changes in the composition or metabolic functions of the microbiome may occur, they must be carefully evaluated to ensure that essential biological functions are unaffected. As such, the purpose of this review is to consider the microbiota of each of the "ecological niches" of the human body and highlight the importance of the microbiota in maintaining a healthy body as well as the possibility of its modulation through the use of probiotics for the prevention and treatment of certain human diseases.

Oral Microbiome Research in Biopsy Samples of Oral Potentially Malignant Disorders and Oral Squamous Cell Carcinoma and Its Challenges

This study aims to evaluate the potential benefits and challenges of integrating oral microbiome research into the clinical management of oral potentially malignant disorders (OPMD) and oral squamous cell carcinoma (OSCC). The oral microbiome has gained significant attention for its role in the pathogenesis and progression of these conditions, with emerging evidence suggesting its value as a diagnostic and prognostic tool. By critically analyzing current evidence and methodological considerations, this manuscript examines whether microbiome analysis in biopsy samples can aid in the early detection, prognosis, and management of OPMD and OSCC. The complexity and dynamic nature of the oral microbiome require a multifaceted approach to fully understand its clinical utility. Based on this review, we conclude that studying the oral microbiome in this context holds significant promise but also faces notable challenges, including methodological variability and the need for standardization. Ultimately, this manuscript addresses the question, “Should such research be undertaken, given the intricate interactions of various factors and the inherent obstacles involved?”, and also emphasizes the importance of further research to optimize clinical applications and improve patient outcomes.

Metagenomic shotgun sequencing reveals the enrichment of Salmonella and Mycobacterium in larynx due to prolonged ethanol exposure

The exposure of ethanol increases the risk of head and neck inflammation and tumor progression. However, limited studies have investigated the composition and functionality of laryngeal microbiota under ethanol exposure. We established an ethanol-exposed mouse model to investigate the changes in composition and function of laryngeal microbiota using Metagenomic shotgun sequencing. In the middle and late stages of the experiment, the laryngeal microbiota of mice exposed to ethanol exhibited obvious distinguished from that of the control group on principal-coordinate analysis (PCoA) plots. Among the highly abundant species, Salmonella enterica and Mycobacterium marinum were likely to be most impacted. Our findings indicated that the exposure to ethanol significantly increased their abundance in larynxes in mice of the same age, which has been confirmed through FISH experiments. Among the species-related functions and genes, metabolism is most severely affected by ethanol. The difference was most obvious in the second month of the experiment, which may be alleviated later because the animal established tolerance. Notable enrichments concerning energy, amino acid, and carbohydrate metabolic pathways occurred during the second month under ethanol exposure. Finally, based on the correlation between species and functional variations, a network was established to investigate relationships among microbiota, functional pathways, and related genes affected by ethanol. Our data first demonstrated the continuous changes of abundance, function and their interrelationship of laryngeal microbiota under ethanol exposure by Metagenomic shotgun sequencing.

Importance

Ethanol may participate in the inflammation and tumor progression by affecting the composition of the laryngeal microbiota. Here, we applied the metagenomic shotgun sequencing instead of 16 S rRNA sequencing method to identify the laryngeal microbiota under ethanol exposure. Salmonella enterica and Mycobacterium marinum are two dominant species that may play a role in the reconstruction of the laryngeal microenvironment, as their local abundance increases following exposure to ethanol. The metabolic function is most evidently impacted, and several potential metabolic pathways could be associated with alterations in microbiota composition. These findings could help us better understand the impact of prolonged ethanol exposure on the microbial composition and functionality in the larynx.

Salivary Metabolic Pathway Alterations in Brazilian E-Cigarette Users

In recent years, the use of electronic cigarettes (e-cigs) has increased. However, their long-term effects on oral health and saliva remain poorly understood. Therefore, this study aimed to evaluate the saliva of e-cig users and investigate possible biomarkers. Participants were divided into two groups: the Electronic Cigarette Group (EG)-25 regular and exclusive e-cig users-and Control Group (CG)-25 non-smokers and non-e-cig users, matched in sex and age to the EG. The clinical analysis included the following parameters: age, sex, heart rate, oximetry, capillary blood glucose, carbon monoxide (CO) concentration in exhaled air, and alcohol use disorder identification test (AUDIT). Qualitative and quantitative analyses of saliva included sialometry, viscosity, pH, and cotinine concentrations. Furthermore, the EG and CG salivary metabolomes were compared using gas chromatography coupled with mass spectrometry (GC-MS). Data were analyzed using the Mann-Whitney test. The MetaboAnalyst 6.0 software was used for statistical analysis and biomarker evaluation. The EG showed high means for exhaled CO concentration and AUDIT but lower means for oximetry and salivary viscosity. Furthermore, 10 metabolites (isoleucine, 2-hydroxyglutaric acid, 3-phenyl-lactic acid, linoleic acid, 3-hydroxybutyric acid, 1,6-anhydroglucose, glucuronic acid, valine, stearic acid, and elaidic acid) were abundant in EG but absent in CG. It was concluded that e-cig users had high rates of alcohol consumption and experienced significant impacts on their general health, including increased cotinine and CO concentration in exhaled air, decreased oximetry, and low salivary viscosity. Furthermore, they showed a notable increase in salivary metabolites, especially those related to inflammation, xenobiotic metabolism, and biomass-burning pathways.

Current situation and influencing factors of oral frailty for community-dwelling older adults in the northeastern border areas of China: A cross-sectional study

OBJECTIVES

Unique lifestyle and cultural factors in China may lead to distinct patterns of risk factors for oral frailty among older adults, especially in regions inhabited by northeastern border minority groups.

METHODS

From July to November 2023, a convenience sampling method was employed to select older adults from three communities in Yanji City as the subjects. Data were collected by a set of questionnaires.

RESULTS

A total of 478 older adults were included, revealing a prevalence rate of 71.6 % for oral frailty. Factors influencing were found to include age, ethnicity, gender, income, number of chronic diseases, body mass index, drinking, physical frailty, sleep disorders, and attitudes towards aging (p < 0.05).

CONCLUSIONS

There is a higher prevalence of oral frailty. It is crucial to prioritize the oral health issues of older adults with high-risk factors and implement targeted intervention measures to reduce and control the occurrence and progression of oral frailty.

Clinical relationships between the intratumoral microbiome and risk factors for head and neck cancer

A bioinformatic analysis is a promising approach to understand the relationship between the vast tumor microbiome and cancer development. In the present study, we studied the relationships between the intratumoral microbiome and classical clinical risk factors using bioinformatics analysis of the Cancer Genome Atlas (TCGA) and the Cancer Microbiome Atlas (TCMA) datasets. We used TCMA database and investigated the abundance of microbes at the genus level in solid normal tissue (n = 22) and the primary tumors of patients with head and neck squamous cell carcinoma (HNSCC) (n = 154) and identified three major tumor microbiomes, Fusobacterium, Prevotella, and Streptococcus. The tissue level of Fusobacterium was higher in primary tumors than in solid normal tissue. However, univariate and multivariate analyses of these 3 microbes showed no significant effects on patient survival. We then extracted 43, 55, or 59 genes that were differentially expressed between the over and under the median groups for Fusobacterium, Prevotella, or Streptococcus using the criteria of >2.5, >1.5, or >2.0 fold and p < 0.05 in the Mann-Whitney U test. The results of a pathway analysis revealed the association of Fusobacterium- and Streptococcus-related genes with the IL-17 signaling pathway and Staphylococcus aureus infection, while Prevotella-associated pathways were not extracted. A protein-protein interaction analysis revealed a dense network in the order of Fusobacterium, Streptococcus, and Prevotella. An investigation of the relationships between the intratumoral microbiome and classical clinical risk factors showed that high levels of Fusobacterium were associated with a good prognosis in the absence of alcohol consumption and smoking, while high levels of Streptococcus were associated with a poor prognosis in the absence of alcohol consumption. In conclusion, intratumoral Fusobacterium and Streptococcus may affect the prognosis of patients with HNSCC, and their effects on HNSCC are modulated by the impact of drinking and smoking.

Oral Microbiome: A Review of Its Impact on Oral and Systemic Health

PURPOSE OF REVIEW

This review investigates the oral microbiome's composition, functions, influencing factors, connections to oral and systemic diseases, and personalized oral care strategies.

RECENT FINDINGS

The oral microbiome is a complex ecosystem consisting of bacteria, fungi, archaea, and viruses that contribute to oral health. Various factors, such as diet, smoking, alcohol consumption, lifestyle choices, and medical conditions, can affect the balance of the oral microbiome and lead to dysbiosis, which can result in oral health issues like dental caries, gingivitis, periodontitis, oral candidiasis, and halitosis. Importantly, our review explores novel associations between the oral microbiome and systemic diseases including gastrointestinal, cardiovascular, endocrinal, and neurological conditions, autoimmune diseases, and cancer. We comprehensively review the efficacy of interventions like dental probiotics, xylitol, oral rinses, fluoride, essential oils, oil pulling, and peptides in promoting oral health by modulating the oral microbiome.

SUMMARY

This review emphasizes the critical functions of the oral microbiota in dental and overall health, providing insights into the effects of microbial imbalances on various diseases. It underlines the significant connection between the oral microbiota and general health. Furthermore, it explores the advantages of probiotics and other dental care ingredients in promoting oral health and addressing common oral issues, offering a comprehensive strategy for personalized oral care.

Oral Microbiome Dysbiosis as a Risk Factor for Stroke: A Comprehensive Review

Stroke represents a significant global health burden, with a substantial impact on mortality, morbidity, and long-term disability. The examination of stroke biomarkers, particularly the oral microbiome, offers a promising avenue for advancing our understanding of the factors that contribute to stroke risk and for developing strategies to mitigate that risk. This review highlights the significant correlations between oral diseases, such as periodontitis and caries, and the onset of stroke. Periodontal pathogens within the oral microbiome have been identified as a contributing factor in the exacerbation of risk factors for stroke, including obesity, dyslipidemia, atherosclerosis, hypertension, and endothelial dysfunction. The alteration of the oral microbiome may contribute to these conditions, emphasizing the vital role of oral health in the prevention of cardiovascular disease. The integration of dental and medical health practices represents a promising avenue for enhancing stroke prevention efforts and improving patient outcomes.

Effect of chronic alcohol consumption on oral microbiota in rats with periodontitis

Background

The imbalance of oral microbiota can contribute to various oral disorders and potentially impact general health. Chronic alcohol consumption beyond a certain threshold has been implicated in influencing both the onset and progression of periodontitis. However, the mechanism by which chronic alcohol consumption affects periodontitis and its association with changes in the oral microbial community remains unclear.

Objective

This study used 16S rRNA gene amplicon sequencing to examine the dynamic changes in the oral microbial community of rats with periodontitis influenced by chronic alcohol consumption.

Methods

Twenty-four male Wistar rats were randomly allocated to either a periodontitis (P) or periodontitis + alcohol (PA) group. The PA group had unrestricted access to alcohol for 10 weeks, while the P group had access to water only. Four weeks later, both groups developed periodontitis. After 10 weeks, serum levels of alanine aminotransferase and aspartate aminotransferase in the rats' serum were measured. The oral swabs were obtained from rats, and 16S rRNA gene sequencing was conducted. Alveolar bone status was assessed using hematoxylin and eosin staining and micro-computed tomography.

Results

Rats in the PA group exhibited more severe periodontal tissue damage compared to those in the periodontitis group. Although oral microbial diversity remained stable, the relative abundance of certain microbial communities differed significantly between the two groups. Actinobacteriota and Desulfobacterota were more prevalent at the phylum level in the PA group. At the genus level, Cutibacterium, Tissierella, Romboutsia, Actinomyces, Lawsonella, Anaerococcus, and Clostridium_sensu_stricto_1 were significantly more abundant in the PA group, while Haemophilus was significantly less abundant. Additionally, functional prediction using Tax4Fun revealed a significant enrichment of carbohydrate metabolism in the PA group.

Conclusion

Chronic alcohol consumption exacerbated periodontitis in rats and influenced the composition and functional characteristics of their oral microbiota, as indicated by 16S rRNA gene sequencing results. These microbial alterations may contribute to the exacerbation of periodontitis in rats due to chronic alcohol consumption.

The Effects of Recreational and Pharmaceutical Substance Use on Oral Microbiomes and Health

Oral health remains one of the most taken for granted parts of human body health, even though poor oral health has now been linked to various diseases, such as cancers, diabetes, autoimmune complications, neurological disorders, and cardiovascular disease, just to name a few. As we review in this paper, substance use or abuse, including alcohol, smoking, recreational drugs, and pharmaceutical drugs can have significant implications on oral health, which in turn can lead to more systemic diseases. In this paper, we show that oral microbiome dysbiosis and inflammatory cytokine pathways are two of the most significant mechanisms contributing to oral health complications from substance use. When substance use decreases beneficial oral species and increases periodontopathogenic strains, a subsequent cascade of oncogenic and inflammatory cytokines is triggered. In this review, we explore these mechanisms and others to determine the consequences of substance use on oral health. The findings are of significance clinically and in research fields as the substance-use-induced deterioration of oral health significantly reduces quality of life and daily functions. Overall, the studies in this review may provide valuable information for future personalized medicine and safer alternatives to legal and pharmaceutical substances. Furthermore, they can lead towards better rehabilitation or preventative initiatives and policies, as it is critical for healthcare and addiction aid specialists to have proper tools at their disposal.

Self-perceived halitosis and associated factors among university students in Dhaka, Bangladesh

BACKGROUND

Bad breath (halitosis) is a common problem affecting psycho-social wellbeing of young people. We aimed to explore the extent of self-perceived halitosis and associated factors among university students in Dhaka, Bangladesh.

METHODS

A cross-sectional study was conducted among university students from November 2021 to April 2022. Six private and two public universities were approached. A total of 318 participants were conveniently selected for the study. A self-administered questionnaire was used for data collection. Students unwilling to participate were excluded. Multivariable logistic regression analysis was used to examine factors associated with halitosis. Statistical analysis was conducted using Stata Version 17.

RESULTS

A total of 55.97% of students had self-perceived halitosis, with females (74.53%) having a significantly higher proportion than males (36.94%) (p < 0.001). A significantly higher proportion of halitosis was found among participants who were overweight ( 61%), had obesity (60.77%), smoked cigarette (46.79%), consumed alcohol (71.43%), lacked exercise (66.29%), were on unhealthy diet (57.35%), consumed coffee/tea (61.35%), breathed through mouth (64.60%), brushed tooth infrequently (85.71%), changed toothbrush after 6 months (77.42%), did not use toothpaste (94.74%), did not use/ sometimes used fluoride toothpaste (75.76%), lacked dental floss use (60.85%), did not use toothpick (62.87%), did chew or sometimes chewed sugar-free chewing gum (75.82%), did not clear / cleaned tongue sometimes (76.14%), did use mouth freshener regularly or occasionally (64.97%), did not use or used mouthwash sometimes (58.87%) were also associated with higher self-perceived halitosis (p < 0.05 for all). Students with gum bleeding, swollen gums, dry mouth, dental caries, food accumulation, and tooth sensitivity had a significantly (p < 0.05 for all) higher proportion of self-perceived halitosis (76.85%, 81.82%, 72.50%, 67.78%, 64.13% and 67.40%, respectively) compared to those without this problem. Being female (OR = 5.04; 95% CI: 2.01-12.62; p < 0.001), alcohol consumers (OR 7.35; 95% CI: 1.77-30.50; p = 0.006); not using sugar free chewing gum (OR = 0.25; 95% CI: 0.10-0.58; p = 0.001), lack of tongue cleaning (OR 4.62; 95% CI: 2.16-9.84; p < 0.001), and gum bleeding (OR = 7.43; 95% CI: 3.00-18.35; p < 0.001) were independently associated with halitosis on multivariable regression.

CONCLUSION

This study reveals a high proportion of self-perceived halitosis and relevant factors. There should be more public education on the causes of halitosis and potential management approaches.

Oral microbiome and its relationship with oral cancer

ABSTRACT

As the initial point for digestion, the balance of oral microorganisms plays an important role in maintaining local and systemic health. Oral dysbiosis, or an imbalance in the oral microbial community, may lead to the onset of various diseases. The presence or abnormal increase of microbes in the oral cavity has attracted significant attention due to its complicated relationship with oral cancer. Oral cancer can remodel microbial profiles by creating a more beneficial microenvironment for its progression. On the other hand, altered microbial profiles can promote tumorigenesis by evoking a complex inflammatory response and affecting host immunity. This review analyzes the oncogenic potential of oral microbiome alterations as a driver and biomarker. Additionally, a potentially therapeutic strategy via the reversal of the oral microbiome dysbiosis in oral cancers has been discussed.

Whole-Genome Metagenomic Analysis of the Oral Microbiota in Patients with Obstructive Sleep Apnea Comorbid with Major Depressive Disorder

Background

Obstructive sleep apnea (OSA) patients commonly experience high rates of depression. This study aims to examine the oral microbiota characteristics of OSA and those with comorbid major depressive disorder (OSA+MDD) patients.

Methods

Participants were enrolled from Aug 2022 to Apr 2023. Polysomnography, psychiatrist interviews, and scales were used to diagnose OSA and MDD. Oral samples were collected from participants by rubbing swabs on buccal mucosa, palate, and gums. Oral microbiota was analyzed via whole-genome metagenomics and bioinformatic analysis followed sequencing. Venous blood was drawn to detect plasma inflammatory factor levels.

Results

The study enrolled 33 OSA patients, 28 OSA+MDD patients, and 28 healthy controls. Significant differences were found in 8 phyla, 229 genera, and 700 species of oral microbiota among the three groups. Prevotellaceae abundance in the OSA and OSA+MDD groups was significantly lower than that in healthy controls. Linear discriminant analysis effect size (LEfSe) analysis showed that Streptococcaceae and Actinobacteria were the characteristic oral microbiota of the OSA and OSA+MDD groups, respectively. KEGG analysis indicates 30 pathways were changed in the OSA and OSA+MDD groups compared with healthy controls, and 23 pathways were changed in the OSA group compared with the OSA+MDD group. Levels of IL-6 in the OSA+MDD group were significantly higher than in the healthy group, correlating positively with the abundance of Schaalia, Campylobacter, Fusobacterium, Alloprevotella, and Candidatus Nanosynbacter in the oral, as well as with Hamilton Anxiety Rating Scale and Hamilton Depression Rating Scale scores.

Conclusion

Significant differences in oral microbiota populations and gene function were observed among the three groups. OSA patients were characterized by a decreased abundance of Prevotellaceae and an increased abundance of Streptococcaceae. OSA+MDD patients had an increased abundance of Actinobacteria. IL-6 might regulate the relationship between depression and the oral microbiota in OSA+MDD patients.

Shared and unique 3D genomic features of substance use disorders across multiple cell types

Recent genome-wide association studies (GWAS) have revealed shared genetic components among alcohol, opioid, tobacco and cannabis use disorders. However, the extent of the underlying shared causal variants and effector genes, along with their cellular context, remain unclear. We leveraged our existing 3D genomic datasets comprising high-resolution promoter-focused Capture-C/Hi-C, ATAC-seq and RNA-seq across >50 diverse human cell types to focus on genomic regions that coincide with GWAS loci. Using stratified LD regression, we determined the proportion of genomewide SNP heritability attributable to the features assayed across our cell types by integrating recent GWAS summary statistics for the relevant traits: alcohol use disorder (AUD), tobacco use disorder (TUD), opioid use disorder (OUD) and cannabis use disorder (CanUD). Statistically significant enrichments (P<0.05) were observed in 14 specific cell types, with heritability reaching 9.2-fold for iPSC-derived cortical neurons and neural progenitors, confirming that they are crucial cell types for further functional exploration. Additionally, several pancreatic cell types, notably pancreatic beta cells, showed enrichment for TUD, with heritability enrichments up to 4.8-fold, suggesting genomic overlap with metabolic processes. Further investigation revealed significant positive genetic correlations between T2D with both TUD and CanUD (FDR<0.05) and a significant negative genetic correlation with AUD. Interestingly, after partitioning the heritability for each cell type's cis-regulatory elements, the correlation between T2D and TUD for pancreatic beta cells was greater (r=0.2) than the global genetic correlation value. Our study provides new genomic insights into substance use disorders and implicates cell types where functional follow-up studies could reveal causal variant-gene mechanisms underpinning these disorders.

The potential value of oral microbial signatures for prediction of oral squamous cell carcinoma based on machine learning algorithms

OBJECTIVE

This study aimed to explore the potential predictive value of oral microbial signatures for oral squamous cell carcinoma (OSCC) risk based on machine learning algorithms.

METHODS

The oral microbiome signatures were assessed in the unstimulated saliva samples of 80 OSCC patients and 179 healthy individuals using 16S rRNA gene sequencing. Four different machine learning classifiers were used to develop prediction models.

RESULTS

Compared with control participants, OSCC patients had a higher microbial dysbiosis index (MDI, p < 0.001). Among four machine learning classifiers, random forest (RF) provided the best predictive performance, followed by the support vector machines, artificial neural networks and naive Bayes. After controlling the potential confounders using propensity score matching, the optimal RF model was further developed incorporating a minimal set of 20 bacteria genera, exhibiting better predictive performance than the MDI (AUC: 0.992 vs. 0.775, p < 0.001).

CONCLUSIONS

The novel MDI and RF model developed in this study based on oral microbiome signatures may serve as noninvasive tools for predicting OSCC risk.

Oral microbial dysbiosis in patients with oral cavity cancers

OBJECTIVES

The pathogenesis of oral cavity cancers is complex. We tested the hypothesis that oral microbiota dysbiosis is associated with oral cavity cancer.

MATERIALS AND METHODS

Patients with primary oral cavity cancer who met the inclusion and exclusion criteria were included in the study. Matching healthy individuals were recruited as controls. Data on socio-demographic and behavioral factors, self-reported periodontal measures and habits, and current dental status were collected using a structured questionnaire and periodontal chartings. In addition to self-reported oral health measures, each participant received a standard and detailed clinical examination. DNA was extracted from saliva samples from patients and healthy controls. Next-generation sequencing was performed by targeting V3-V4 gene regions of the 16 S rRNA with subsequent bioinformatic analyses.

RESULTS

Patients with oral cavity cancers had a lower quality of oral health than healthy controls. Proteobacteria, Aggregatibacter, Haemophilus, and Neisseria decreased, while Firmicutes, Bacteroidetes, Actinobacteria, Lactobacillus, Gemella, and Fusobacteria increased in oral cancer patients. At the species level, C. durum, L. umeaens, N. subflava, A. massiliensis, and V. dispar were significantly lower, while G. haemolysans was significantly increased (p < 0.05). Major periodontopathogens associated with periodontal disease (P. gingivalis and F.nucleatum) increased 6.5- and 2.8-fold, respectively.

CONCLUSION

These data suggested that patients with oral cancer had worse oral health conditions and a distinct oral microbiome composition that is affected by personal daily habits and may be associated with the pathogenicity of the disease and interspecies interactions.

CLINICAL RELEVANCE

This paper demonstrates the link between oral bacteria and oral cancers, identifying mechanistic interactions between species of oral microbiome.

Adolescent alcohol use is associated with differences in the diversity and composition of the oral microbiome

BACKGROUND

Adolescence is a sensitive stage of oral microbial development that often coincides with the initiation and escalation of alcohol use. Thus, adolescents may be particularly susceptible to alcohol-induced alterations in the oral microbiome, though minimal research has been done in this area. Understanding the connection between the oral microbiome and alcohol use during adolescence is important to understand fully the biological consequences of alcohol use to mitigate potential adverse outcomes.

METHODS

Saliva samples were collected from adolescents aged 17-19 who used alcohol heavily (n = 21, 52.4% female) and those who did not use alcohol or any other substances (n = 18, 44.4% female). We utilized 16S rRNA sequencing to examine differences in microbial diversity and composition between the groups.

RESULTS

For alpha diversity, evenness was significantly lower in the drinking group than the control group as indicated by Pielou's evenness, Shannon, and Simpson indices. There were no statistically significant findings for beta diversity. Differential abundance analyses revealed higher abundances of Rothia and Corynebacterium in the alcohol-using group using both centered-log-ratio and relative abundance normalization. These genera are known for their high capacity to convert alcohol into acetaldehyde, a toxic metabolite reported to play a role in the neurobiological effects of alcohol. An unclassified Clostridia UCG-014, Streptobacillus, Comamonas, unclassified Lachnospiraceae, and Parvimonas were also identified as significantly different between groups when using only one of the normalization techniques.

CONCLUSIONS

This is the first study designed specifically to compare the oral microbiome of adolescents who use alcohol with that of control participants. Our findings reveal distinct alcohol-related differences in microbial composition and taxon abundance, emphasizing the importance of understanding the impact on the oral microbiome of alcohol use during adolescence. Because the oral microbiome is malleable, this study provides foundational work for future prevention and intervention studies.

Microbial Communities and Functional Genes in Periodontitis and Healthy Controls

BACKGROUND

Periodontitis is a chronic progressive disease and the leading cause of tooth loss in adults. Recent studies have shown the impact of oral microbial communities on systemic health and diseases such as cancer, atherosclerosis, rheumatoid arthritis, inflammatory bowel disease, diabetes, hypertension, and Alzheimer's disease. In previous case control studies investigatin the relationship between periodontal disease and the oral microbiota, little attention has been paid to the intersections of these domains.

METHODS

Here, we used high-throughput 16S rRNA sequencing to analyse the differences in the microbial composition in saliva between a group of patients with chronic periodontitis (C; n = 51) and a healthy control group (H; n = 61) and predicted the functional gene composition by Phylogenetic Investigation of Communities by Reconstruction of Unobserved States.

RESULTS

We found significant alterations in oral microbial diversity between C and H (P = 0.002). Sixteen genera were significantly different between C and H, and 15 of them were enriched in C linear discriminant analysis (LDA > 2). Fifty functional genes were significantly different between C and H, and 34 of them were enriched in C (P < .025).

CONCLUSIONS

Periodontitis is associated with significant changes in the oral microbial community.

Alcohol and Periodontal Disease: A Narrative Review

The scientific literature dealing with alcohol and alcoholic beverages revealed that these drinks possess an adverse impact on periodontal tissues. Additionally, other principal risk factors include tobacco, smoking, poor oral hygiene, etc. It has been observed that among chronic alcoholics, there are further issues, such as mental, social, and physical effects, that promote alcoholism. These people may have weak immunity for defense against pathogenic organisms and bacteria. Thus, chances of gingival bleeding, swollen gums, bad breath, and increased bone loss are there. Different alcoholic beverages in the market cause less salivation; these beverages contain sugars that promote acid production in the oral cavity by pathogens that demineralize the enamel and damage gum and teeth. This chronic alcohol consumption can progress into different types of oral disorders, including cancer, halitosis, and caries, and is also associated with tobacco and smoking. Chronic alcohol consumption can cause alteration of the oral microbiome and increase oral pathogens, which lead to periodontal disease and an environment of inflammation created in the body due to malnutrition, diminished immunity, altered liver condition, brain damage, and gut microbiota alteration. Heavily colored alcoholic beverages produce staining on teeth and, due to less saliva, may cause other toxic effects on the periodontium. Over-dependency on alcohol leads to necrotizing lesions such as necrotizing gingivitis, necrotizing periodontitis, and necrotizing stomatitis. These pathological impairments instigate severe damage to oral structures. Therefore, proper counseling by the attending dental surgeon and related health professionals is urgently required for the patient on the basis that the individual case needs to go away from the regular heavy consumption of alcohol.

A comparison between full-length 16S rRNA Oxford nanopore sequencing and Illumina V3-V4 16S rRNA sequencing in head and neck cancer tissues

Describing the microbial community within the tumour has been a key aspect in understanding the pathophysiology of the tumour microenvironment. In head and neck cancer (HNC), most studies on tissue samples have only performed 16S rRNA short-read sequencing (SRS) on V3-V5 region. SRS is mostly limited to genus level identification. In this study, we compared full-length 16S rRNA long-read sequencing (FL-ONT) from Oxford Nanopore Technology (ONT) to V3-V4 Illumina SRS (V3V4-Illumina) in 26 HNC tumour tissues. Further validation was also performed using culture-based methods in 16 bacterial isolates obtained from 4 patients using MALDI-TOF MS. We observed similar alpha diversity indexes between FL-ONT and V3V4-Illumina. However, beta-diversity was significantly different between techniques (PERMANOVA - R2 = 0.131, p < 0.0001). At higher taxonomic levels (Phylum to Family), all metrics were more similar among sequencing techniques, while lower taxonomy displayed more discrepancies. At higher taxonomic levels, correlation in relative abundance from FL-ONT and V3V4-Illumina were higher, while this correlation decreased at lower levels. Finally, FL-ONT was able to identify more isolates at the species level that were identified using MALDI-TOF MS (75% vs. 18.8%). FL-ONT was able to identify lower taxonomic levels at a better resolution as compared to V3V4-Illumina 16S rRNA sequencing.

Longitudinal profiling of the microbiome at four body sites reveals core stability and individualized dynamics during health and disease

To understand the dynamic interplay between the human microbiome and host during health and disease, we analyzed the microbial composition, temporal dynamics, and associations with host multi-omics, immune, and clinical markers of microbiomes from four body sites in 86 participants over 6 years. We found that microbiome stability and individuality are body-site specific and heavily influenced by the host. The stool and oral microbiome are more stable than the skin and nasal microbiomes, possibly due to their interaction with the host and environment. We identify individual-specific and commonly shared bacterial taxa, with individualized taxa showing greater stability. Interestingly, microbiome dynamics correlate across body sites, suggesting systemic dynamics influenced by host-microbial-environment interactions. Notably, insulin-resistant individuals show altered microbial stability and associations among microbiome, molecular markers, and clinical features, suggesting their disrupted interaction in metabolic disease. Our study offers comprehensive views of multi-site microbial dynamics and their relationship with host health and disease.

Longitudinal profiling of the microbiome at four body sites reveals core stability and individualized dynamics during health and disease

To understand dynamic interplay between the human microbiome and host during health and disease, we analyzed the microbial composition, temporal dynamics, and associations with host multi-omics, immune and clinical markers of microbiomes from four body sites in 86 participants over six years. We found that microbiome stability and individuality are body-site-specific and heavily influenced by the host. The stool and oral microbiome were more stable than the skin and nasal microbiomes, possibly due to their interaction with the host and environment. Also, we identified individual-specific and commonly shared bacterial taxa, with individualized taxa showing greater stability. Interestingly, microbiome dynamics correlated across body sites, suggesting systemic coordination influenced by host-microbial-environment interactions. Notably, insulin-resistant individuals showed altered microbial stability and associations between microbiome, molecular markers, and clinical features, suggesting their disrupted interaction in metabolic disease. Our study offers comprehensive views of multi-site microbial dynamics and their relationship with host health and disease.

Study Highlights

The stability of the human microbiome varies among individuals and body sites.Highly individualized microbial genera are more stable over time.At each of the four body sites, systematic interactions between the environment, the host and bacteria can be detected.Individuals with insulin resistance have lower microbiome stability, a more diversified skin microbiome, and significantly altered host-microbiome interactions.

The adolescent and young adult microbiome and its association with substance use: a scoping review

AIMS

The microbiome is a critical factor in health throughout human development. The aims of this scoping review are to (i) elucidate the differences between the youth (post-natal day 21-65 for rodents, 2-7 years for non-human primates, and 10-25 years for humans) microbiome with other life stages and (ii) identify youth-specific microbial changes associated with substance use.

METHODS

Peer-reviewed studies published up to May 2023 were identified in PubMed and SCOPUS and included gut and oral microbiome studies from rodents, non-human primates, and humans (N = 1733). Twenty-six articles were determined eligible based on inclusion criteria (aim 1: n = 19, aim 2: n = 7).

RESULTS

The adolescent and young adult oral and gut microbiomes are distinct compared to other life stages, within both non-human and human models. While there is limited research in this area, the microbiome appears to be vulnerable to substance use exposure earlier in life, including substances commonly initiated and escalated during adolescence and young adulthood (i.e. alcohol, cannabis, and tobacco).

CONCLUSIONS

Studies across the lifespan indicate that adolescence and young adulthood are distinct periods of development, where the microbiome is sensitive to exposures, including substance use. There is a need for more studies focused on the adolescent and young adult microbiome and substance use, as well as focused on the oral microbiome during this developmental period. Understanding the gut and oral microbiome during adolescence and young adulthood may provide insight into the pathophysiology of substance use disorders.

Analysis of the influence of host lifestyle (coffee consumption, drinking, and smoking) on Korean oral microbiome

If a DNA sample collected in the field is old or degraded, short tandem repeat analysis is difficult to perform, a representative analysis method currently used for individual identification. Given that microorganisms exist everywhere and within the human body, in similar amounts to human cells, microbial analysis could be used to identify individuals even in cases in which human DNA-based identification is difficult. Research has demonstrated that the types of microorganisms within the human body differ depending on various internal or external factors, such as body part or bodily fluid type, lifestyle, geographical area of residence, sex, and age. In this study, we aimed to examine the relationship between lifestyle factors and the composition and diversity of the oral microbiome in individuals living in Korea. We collected 43 saliva samples from Korean individuals and analyzed the oral microbiome and its variations due to external factors, such as coffee consumption, drinking, and smoking. Linear discriminant analysis effect size revealed that Oribacterium, Campylobacter, and Megasphaera were abundant in coffee consumers, whereas Saccharimonadales, Clostridia, and Catonella were abundant in alcohol non-drinkers. We found increased levels of Stomatobaculum in the saliva of smokers, compared with that of non-smokers. Thus, our analysis revealed characteristic microorganisms for each parameter that was evaluated (coffee consumption, smoking, drinking). Consequently, our study provides insight into the oral microbiome in the Korean population and lays the foundation for developing the Korean Forensic Microbiome Database.

Alcohol Consumption and the Diversity of the Oral Microbiome in Postmenopausal Women

BACKGROUND

Alcohol reduces neutrophil function and decreases salivary flow, which could affect the composition of the oral microbiome.

OBJECTIVE

We hypothesized that the α- and β-diversity of the oral microbiome and the relative abundance of bacterial taxa would differ by frequency and type of alcohol consumption.

METHODS

We used a food frequency questionnaire to assess the frequency of consumption of beer, wine, and liquor (drinks/week) in a sample of 1179 postmenopausal women in the Osteoporosis and Periodontal Disease Study. Women were categorized as nondrinkers, drinking <1 drink/wk, ≥1 to <7 drinks/wk, or ≥7 drinks/wk for total alcohol consumption and for beer, wine, and liquor consumption. The composition and diversity of the oral microbiome was assessed from subgingival plaque samples using 16S ribosomal RNA amplicon sequencing. Permutational multivariate analysis of variance (PERMANOVA) was used to examine β-diversity (between-sample diversity) in the microbiome between alcohol consumption categories. Analysis of covariance was used to examine the mean α-diversity (within-sample diversity), assessed by the Shannon index (species evenness), Chao1 index (species richness), and observed operational taxonomic unit (OTU) count and the mean relative abundance of 245 bacterial taxa across alcohol consumption categories.

RESULTS

Over half of the participants (67%) consumed alcohol, with 14% reporting ≥1 drink/d. The β-diversity across categories of total alcohol consumption, but not categories of alcohol type, was statistically significantly different (P for PERMANOVA = 0.016). Mean α-diversity measures were statistically significantly higher (P < 0.05) in the highest category of total alcohol and wine consumption compared to nondrinkers; no significant associations were found for beer or liquor consumption. The relative abundance of 1 OTU, Selenomonassp._oral_taxon_133, was significantly lower in the highest level of total alcohol consumption compared to nondrinkers after adjustment for multiple comparisons.

CONCLUSIONS

Alcohol consumption was associated with the diversity and composition of the subgingival microbiome.

Alcohol consumption modulates Candida albicans-induced oral carcinogenesis and progression

OBJECTIVES

This study aimed to determine the impact of low levels of alcohol consumption on the interaction of the oral cavity with Candida albicans, a species that is commonly found at higher levels in the oral cavities of regular alcohol consumers, patients with pre-malignant diseases, and patients with existing oral cancer (OC).

METHODS

The gingival squamous cell carcinoma cell line, Ca9-22, was subjected to low-level ethanol exposure before co-culture with heat-inactivated C. albicans (HICA). We performed cell viability assays, measured reactive oxygen species, and used Western blot analysis for cell death markers to examine the effect of ethanol and HICA on cells. Scratch assays and anchorage-independent growth assays were used to determine cell behavioral changes.

RESULTS

The results showed that ethanol in combination with HICA exacerbated cell death and cell cycle disruption, delayed NF-κB signaling, increased TIMP-2 secretion, and subsequently decreased MMP-2 secretion when compared to exposure to HICA alone. Conversely, both ethanol and HICA independently increased proliferation of Ca9-22 cells in scratch assays, and in combination, increased their capacity for anchorage-independent growth.

CONCLUSION

Low levels of ethanol may provide protective effects against Candida-induced inflammatory oral carcinogenesis or OC progression.

Acetaldehyde as a Food Flavoring Substance: Aspects of Risk Assessment

The Senate Commission on Food Safety (SKLM) of the German Research Foundation (DFG) has reviewed the currently available data in order to assess the health risks associated with the use of acetaldehyde as a flavoring substance in foods. Acetaldehyde is genotoxic in vitro. Following oral intake of ethanol or inhalation exposure to acetaldehyde, systemic genotoxic effects of acetaldehyde in vivo cannot be ruled out (induction of DNA adducts and micronuclei). At present, the key question of whether acetaldehyde is genotoxic and mutagenic in vivo after oral exposure cannot be answered conclusively. There is also insufficient data on human exposure. Consequently, it is currently not possible to reliably assess the health risk associated with the use of acetaldehyde as a flavoring substance. However, considering the genotoxic potential of acetaldehyde as well as numerous data gaps that need to be filled to allow a comprehensive risk assessment, the SKLM considers that the use of acetaldehyde as a flavoring may pose a safety concern. For reasons of precautionary consumer protection, the SKLM recommends that the scientific base for approval of the intentional addition of acetaldehyde to foods as a flavoring substance should be reassessed.

A systematic review and meta-analysis of prognostic indicators in patients with head and neck malignancy treated with immune checkpoint inhibitors

INTRODUCTION

Tumor immunotherapy has recently emerged as a crucial focal point in oncology treatment research. Among tumor immunotherapy approaches, tumor immune checkpoint inhibitors (ICIs) have attracted substantial attention in clinical research. However, this treatment modality has benefitted only a limited number of patients. We conducted a meta-analysis of various biomarkers to decipher their prognostic implications in patients with head and neck squamous cell carcinoma (HNSCC) who are treated with ICIs, and thus identify predictive markers with practical clinical relevance.

METHODS

A systematic search of electronic databases was conducted to identify clinical studies that examined the correlation between biomarkers and treatment outcomes in the HNSCC patients. The included articles were screened and analyzed to extract data regarding overall survival (OS) and progression-free survival (PFS).

RESULTS

The relationship between the biomarkers included in the summary and prognosis was as follows: HPV positivity was associated with improved OS (HR = 0.76, 95% CI = 0.58-1.99), PFS (HR = 1.16, 95% CI = 0.81-1.67), and response (OR = 1.67, 95% CI = 1.37-2.99). PD-L1 positivity was associated with OS (HR = 0.71, 95% CI = 0.59-0.85), PFS (HR = 0.56 95% CI = 0.43-0.73), and response (OR = 2.16, 95% CI = 1.51-3.10). Neither HPV positivity nor PD-L1 positivity was associated with DCR. The following markers were collected for OS and PFS data and were associated with longer OS: lower Glasgow prognostic score (GPS/mGPS) grading, lower PS grading, high body mass index (BMI), low neutrophil-to-lymphocyte ratio (NLR), low platelet-to-lymphocyte ratio (PLR), high albumin (Alb), low lactate dehydrogenase (LDH). Factors associated with better PFS were lower GPS/mGPS grading, lower PS grading, high BMI, low NLR, high absolute lymphocyte count, and low LDH. Hyperprogressive disease was associated with worse OS and PFS. Fewer clinical studies have been completed on the tumor microenvironment and hypoxia, microsatellite instability/DNA mismatch repair, and microbiome and systematic analysis is difficult.

CONCLUSION

In our meta-analysis, different immune checkpoint factors were associated with different prognoses in HNSCC patients receiving immunotherapy. HPV, PD-L1, BMI, Alb, HPD, PS, GPS/mGPS, LDH, NLR, and PLR predicted the ICI outcome in HNSCC patients.

Streptococcus strain D19T as a probiotic candidate to modulate oral health

BACKGROUND

As probiotics protect host cells, they are used to treat bacterial infections. It has been indicated that probiotics may prevent or reduce the attachment of pathogens to host cells. In this study, Streptococcus strain D19T was isolated from the oropharynx of a healthy child, and its adhesion performance and Staphylococcus aureus adhesion inhibition effect were analysed using human bronchial epithelial (16-HBE) cells, as an in vitro cell model. We evaluated the probiotic properties of the D19T strain based on its acid-base, bile salt, and lysozyme tolerance; antibacterial activity; cytotoxicity; antibiotic sensitivity; in vitro adhesion to 16-HBE cells; and competitive, exclusion, and displacement effects against S. aureus.

RESULTS

Streptococcus strain D19T showed tolerance to a PH range of 2-5 and 0.5-1% bile. However, it was more tolerant to 0.5% bile than to 1% bile. The strain also demonstrated an ability to adapt to maladaptive oropharyngeal conditions (i.e., tolerating 200 µg/mL lysozyme). It was resistant to 0.8 mM H2O2. The results also demonstrated that D19T exhibited inhibitory activities against various common pathogenic bacteria. Furthermore, D19T was not toxic to 16-HBE cells at different multiplicities of infection and was sensitive to most antibiotics tested. The adhesion rate of D19T cells to 16-HBE cells was 47% ± 1.2%, which was significantly higher than that of S. aureus to 16-HBE cells. The competition, exclusion, and displacement assay results showed that D19T has good inhibitory effect against S. aureus adhesion.

CONCLUSIONS

The present study revealed that Streptococcus strain D19T has the potential to be developed as a respiratory microbiota preparations.

Alcohol consumption and oral microbiome composition in a sample of healthy young adults

The oral microbiomes of 24 healthy adults (50% female; mean age = 24.3) were examined using 16 s ribosomal RNA sequencing and compared between light and heavy drinkers. Beta diversity was related at the trend level to drinking group, and light drinkers had significantly higher abundances of key oral taxa such as Lactobacillales. These preliminary results may offer insight into early effects of heavy drinking on the composition of the oral microbiome.

The Oral Microbiome Profile of Water Polo Players Aged 16-20

OBJECTIVES

Chlorine has a strong antibacterial property and is the disinfectant most frequently used in swimming pools. Therefore, the microbiota community in the oral cavity of those who practice water sports is assumed to be special due to their regular immersion in water. Adverse changes in the composition of oral cavity microbiota may have serious health consequences. We aimed to compare the oral microbiome between water polo players and non-athletes. We hypothesized that the oral cavity microbiota community differed between water polo players and non-athletes.

MATERIALS AND METHODS

Altogether, 124 water polo players (62 males and 62 females, aged between 9 and 20 years) and 16 non-athlete youths (control group, eight males and eight females, aged between 16 and 20 years, mean age + SD = 17.1 + 1.4 years) who participated in body structure examinations voluntarily agreed to participate in the study. In a randomly selected subsample of water polo players (n: 29, aged between 16 and 20 years, mean age + SD = 17.3 + 1.0 years), saliva samples were also collected. Saliva samples were collected from all non-athlete youths (n: 16, aged between 16 and 20 years). The oral microbiome was determined from a saliva sample, and DNA was isolated using the QIAmp DNA Blood Mini Kit. The 16S rRNA gene amplicon sequencing method was used to analyze the microbiome community. PCR primers were trimmed from the sequence reads with Cutadapt. R library DADA2 was used to process reads in the abundance analysis.

RESULTS

In general, Streptococcus, Veilonella, and Prevotella genera constituted more than 50% of the oral microbiome community in the two participant groups combined (n = 45). The oral microbial profile had significant sexual dimorphism and differed between water polo players and the non-athletes. Compared to females, males had a higher (p < 0.05) relative abundance of the Atopobium (medium effect size) and Pravotella_7 (very large effect size) genera and a lower (p < 0.05) relative abundance of the Fusobacterium (large effect size), Gemella (large effect size), and Streptococcus (large effect size) genera. Compared to non-athletes, water polo players had higher (p < 0.05, medium effect size) relative abundance of the genus Veillonella and lower (p < 0.05, large effect size) relative abundance of the genus Gemella.

CONCLUSIONS

The results suggest that regular water training can unfavorably alter the composition of the oral microbial community.

Mouthwash Effects on the Oral Microbiome: Are They Good, Bad, or Balanced?

This narrative review describes the oral microbiome, and its role in oral health and disease, before considering the impact of commonly used over-the-counter (OTC) mouthwashes on oral bacteria, viruses, bacteriophages, and fungi that make up these microbial communities in different niches of the mouth. Whilst certain mouthwashes have proven antimicrobial actions and clinical effectiveness supported by robust evidence, this review reports more recent metagenomics evidence, suggesting that mouthwashes such as chlorhexidine may cause "dysbiosis," whereby certain species of bacteria are killed, leaving others, sometimes unwanted, to predominate. There is little known about the effects of mouthwashes on fungi and viruses in the context of the oral microbiome (virome) in vivo, despite evidence that they "kill" certain viral pathogens ex vivo. Evidence for mouthwashes, much like antibiotics, is also emerging with regards to antimicrobial resistance, and this should further be considered in the context of their widespread use by clinicians and patients. Therefore, considering the potential of currently available OTC mouthwashes to alter the oral microbiome, this article finally proposes that the ideal mouthwash, whilst combatting oral disease, should "balance" antimicrobial communities, especially those associated with health. Which antimicrobial mouthwash best fits this ideal remains uncertain.

Oral Pathogenic Bacteria and the Oral-Gut-Liver Axis: A New Understanding of Chronic Liver Diseases

Liver diseases have long been a prevalent cause of morbidity and mortality, and their development and progression involve multiple vital organs throughout the body. Recent studies on the oral-gut-liver axis have revealed that the oral microbiota is associated with the pathophysiology of chronic liver diseases. Since interventions aimed at regulating oral biological disorders may delay the progress of liver disease, it is crucial to better comprehend this process. Oral bacteria with potential pathogenicity have been extensively studied and are closely related to several types of chronic liver diseases. Therefore, this review will systemically describe the emerging role of oral pathogenic bacteria in common liver diseases, including alcoholic liver disease (ALD), non-alcoholic steatohepatitis (NASH), non-alcoholic fatty liver disease (NAFLD), cirrhosis, autoimmune liver diseases (AILD), and liver cancer, and bring in new perspectives for future research.

Alcohol drinking alters oral microbiota to modulate the progression of alcohol-related liver disease

Alcohol-related liver disease (ALD) is one of the leading causes of liver-related death worldwide. However, roles of oral microbiota in regulating the progression of ALD remain unknown. Here, we fed mice with control or ethanol diet to establish chronic-plus-binge ALD model. 16S ribosomal DNA sequencing was performed on oral and cecum samples. We demonstrated that alcohol drinking influenced bacterial richness, microbial structure, and composition in oral samples of ethanol-fed mice compared with control mice. Alcohol consumption also remodeled relationships among oral microbes and altered functions of oral microbiota. Furthermore, oral microbiota, such as Streptococcus, Helicobacter, Alloprevotella, and Psychrobacter were closely associated with ALD parameters. Finally, we observed Sutterellaceae_uncultured, Dyella, and Gemmatimonas possibly translocated along with oral-gut axis and positively correlated with the severity of ALD. Altogether, alcohol consumption reprogramed composition and functions of oral microbiota to promote ALD progression, suggesting that oral microbes might become a new target for ALD therapy.

Associations of Dietary Inflammatory Potential with Esophageal Precancerous Lesions and Esophageal Squamous-Cell Cancer: A Cross-Sectional Study

Chronic inflammation plays a central role in the progression from esophageal precancerous lesions (EPLs) to esophageal squamous-cell cancer (ESCC). However, few studies have investigated the relationship between the overall inflammatory potential of diets and EPLs and ESCC. We aimed to study the association between the Dietary Inflammatory Index (DII) and EPLs and ESCC. As part of the National Cohort of Esophageal Cancer (NCEC) in China, 3967 residents (1993 men and 1974 women) aged from 40 to 69 years living in Yanting County received free gastroscopy screenings from 2017 to 2019. Dietary intake during the past year was assessed at enrollment of the cohort before screening and DII scores were calculated based on 28 food parameters. EPLs (classified into mild, moderate, and severe dysplasia) and ESCC were histologically confirmed by biopsy. Multivariable logistic regression was used to examine the associations of DII scores with EPLs and ESCC. A total of 312 participants were diagnosed with EPLs (226 with mild dysplasia, 40 with moderate dysplasia, and 46 with severe dysplasia) and 72 were diagnosed with ESCC. A statistically significant positive association was observed between DII scores and overall EPLs (ORT3 vs. T1 = 1.45, 95%CI = 1.01-2.09); the association was similar but not statistically significant for mild dysplasia (ORone-unit-increment = 1.11, 95%CI = 0.95-1.34) and for moderate and severe dysplasia combined (ORone-unit-increment = 1.15, 95%CI = 0.87-1.51). The association with ESCC was similar in magnitude but not significant, likely due to the small number of cases. In this cross-sectional study of a population in China at high risk of ESCC, DII scores were positively associated with odds of EPLs and ESCC. Consumption of anti-inflammatory foods may be beneficial to prevent EPLs and ESCC.

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.

Intratumor microbiota: a novel tumor component

Bacteria have been found in tumors for over 100 years, but the irreproducibility of experiments on bacteria, the limitations of science and technology, and the contamination of the host environment have severely hampered most research into the role of bacteria in carcinogenesis and cancer treatment. With the development of molecular tools and techniques (e.g., macrogenomics, metabolomics, lipidomics, and macrotranscriptomics), the complex relationships between hosts and different microorganisms are gradually being deciphered. In the past, attention has been focused on the impact of the gut microbiota, the site where the body's microbes gather most, on tumors. However, little is known about the role of microbes from other sites, particularly the intratumor microbiota, in cancer. In recent years, an increasing number of studies have identified the presence of symbiotic microbiota within a large number of tumors, bringing the intratumor microbiota into the limelight. In this review, we aim to provide a better understanding of the role of the intratumor microbiota in cancer, to provide direction for future experimental and translational research, and to offer new approaches to the treatment of cancer and the improvement of patient prognosis.

The association between oral and gut microbiota in male patients with alcohol dependence

Introduction

The relationship between oral and gut microbiota in alcohol dependence (AD) is not well understood, particularly the effects of oral microbiota on the intestinal microbiota. The current study aimed to explore the association between oral and gut microbiota in AD to clarify whether oral microbiota could ectopically colonize into the gut.

Methods

16S rRNA sequence libraries were used to compare oral and gut microbial profiles in persons with AD and healthy controls (HC). Source Tracker and NetShift were used to identify bacteria responsible for ectopic colonization and indicate the driver function of ectopic colonization bacteria.

Results

The α-diversity of oral microbiota and intestinal microbiota was significantly decreased in persons with AD (all p < 0.05). Principal coordinate analysis indicated greater similarity between oral and gut microbiota in persons with AD than that in HC, and oral-gut overlaps in microbiota were found for 9 genera in persons with AD relative to only 3 genera in HC. The contribution ratio of oral microbiota to intestinal microbiota composition in AD is 5.26% based on Source Tracker，and the AD with ectopic colonization showed the daily maximum standard drinks, red blood cell counts, hemoglobin content, and PACS scores decreasing (all p < 0.05).

Discussion

Results highlight the connection between oral-gut microbiota in AD and suggest novel potential mechanistic possibilities.