Oral Microbiota Research Articles

Multi-site analysis of biosynthetic gene clusters from the periodontitis oral microbiome.

Background. Bacteria significantly influence human health and disease, with bacterial biosynthetic gene clusters (BGCs) being crucial in the microbiome-host and microbe-microbe interactions.Gap statement. Despite extensive research into BGCs within the human gut microbiome, their roles in the oral microbiome are less understood.Aim. This pilot study utilizes high-throughput shotgun metagenomic sequencing to examine the oral microbiota in different niches, particularly focusing on the association of BGCs with periodontitis.Methodology. We analysed saliva, subgingival plaque and supragingival plaque samples from periodontitis patients (n=23) and controls (n=16). DNA was extracted from these samples using standardized protocols. The high-throughput shotgun metagenomic sequencing was then performed to obtain comprehensive genetic information from the microbial communities present in the samples.Results. Our study identified 10 742 BGCs, with certain clusters being niche-specific. Notably, aryl polyenes and bacteriocins were the most prevalent BGCs identified. We discovered several 'novel' BGCs that are widely represented across various bacterial phyla and identified BGCs that had different distributions between periodontitis and control subjects. Our systematic approach unveiled the previously unexplored biosynthetic pathways that may be key players in periodontitis.Conclusions. Our research expands the current metagenomic knowledge of the oral microbiota in both healthy and periodontally diseased states. These findings highlight the presence of novel biosynthetic pathways in the oral cavity and suggest a complex network of host-microbe and microbe-microbe interactions, potentially influencing periodontal disease. The BGCs identified in this study pave the way for future investigations into the role of small-molecule-mediated interactions within the human oral microbiota and their impact on periodontitis.

Salivary biomarkers: a promising approach for predicting immunotherapy response in head and neck cancers.

Head and neck cancers, including cancers of the mouth, throat, voice box, salivary glands, and nose, are a significant global health issue. Radiotherapy and surgery are commonly used treatments. However, due to treatment resistance and disease recurrence, new approaches such as immunotherapy are being explored. Immune checkpoint inhibitors (ICIs) have shown promise, but patient responses vary, necessitating predictive markers to guide appropriate treatment selection. This study investigates the potential of non-invasive biomarkers found in saliva, oral rinses, and tumor-derived exosomes to predict ICI response in head and neck cancer patients. The tumor microenvironment significantly impacts immunotherapy efficacy. Oral biomarkers can provide valuable information on composition, such as immune cell presence and checkpoint expression. Elevated tumor mutation load is also associated with heightened immunogenicity and ICI responsiveness. Furthermore, the oral microbiota may influence treatment outcomes. Current research aims to identify predictive salivary biomarkers. Initial studies indicate that tumor-derived exosomes and miRNAs present in saliva could identify immunosuppressive pathways and predict ICI response. While tissue-based markers like PD-L1 have limitations, combining multiple oral fluid biomarkers could create a robust panel to guide treatment decisions and advance personalized immunotherapy for head and neck cancer patients.

Characterization of lingual microbiota in pediatric geographic tongue.

Geographic tongue is an oral mucosal lesion affecting the tongue. The association between geographic tongue and the mucosal microbiota in children remains unclear. To characterize the feature of lingual microbiota in pediatric geographic tongue, lingual swabs were collected from lesion sites and healthy sites of 25 patients with geographic tongue (14 males and 11 females; age 5.21 ±2.94 years) and 19 controls (10 males and 9 females; age 5.31±2.82 years). DNA was extracted and the 16S rRNA was amplificated, sequenced and analyzed. The lingual microbiota composition was significantly different between children with geographic tongue and the healthy cohort; Streptobacillus was reduced in geographic tongue, while Catonella, Bacillus and Oribacterium were overrepresented. When the lesions and the normal mucosa were compared, an increased abundance of Prevotella oris was observed. Our results provided new insight into the association between oral microbiota and pediatric geographic tongue.

Evaluation of the antimicrobial activity of chemical and herbal toothpastes on selected clinical microbial oral flora

Background: Microbes are most commonly found associated with oral diseases. Globally, researchers along with the world Health Organization (WHO) suggested that this could be due to poor oral health and encourage all individuals to practice good oral hygiene using daily oral health products. The study aimed to determine the antimicrobial effects of toothpastes, as acclaimed by the manufacturers, to selected microbial flora involved in oral infections. Methodology: The antimicrobial activity of 6 toothpastes (3 herbal and 3 chemical) was tested against 3 clinical microbial isolates; Staphylococcus aureus, Escherichia coli and Candida albicans, with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of each toothpaste determined for each microbial isolate using the broth dilution method. Results: Colgate exhibited the highest inhibitory activity against S. aureus with respective MIC and MBC of 125mg/ml and 125mg/ml, followed by Oral-B with MIC and MBC of 125mg/ml and 500mg/ml, Dabur herbal with MIC and MBC of 250mg/ml and 500mg/ml, and Longrich with MIC of 500mg/ml and MBC of 1000mg/ml. Colgate and CloseUp exhibited highest inhibitory activity against E. coli with respective MIC and MBC of 125mg/ml and 500mg/ml, followed by Dabur herbal with MIC of 500mg/ml but no MBC. Colgate exhibited the highest inhibitory activity against C. albicans with respective MIC and MBC of 125mg/ml and 500mg/ml, followed by CloseUp with MIC of 500mg/ml, Longrich with MIC of 500mg/ml and MBC of 1000mg/ml, and oral-B with MIC of 500mg/ml but no MBC. Longrich and Oral-B exhibited no MIC/MBC against E. coli while Gavia charcoal exhibited no MIC/MBC against all the 3 microbial isolates at the concentrations used in the assay.Conclusion: The results obtained showed that chemically formulated toothpastes (Colgate, CloseUp and Oral-B) had higher inhibitory activity on microbial isolates than herbal toothpastes (Longrich, Dabur herbal and Gavia charcoal). This supports the manufacturers claim for the chemical toothpastes used, however, the herbal toothpastes showed little or no inhibitory effects on the microbial flora.

Probing the oral-brain connection: oral microbiome patterns in a large community cohort with anxiety, depression, and trauma symptoms, and periodontal outcomes

The role of the oral microbiome in mental health has recently been appreciated within the proposed oral-brain axis. This study examined the structure and composition of the salivary microbiome in a large-scale population-based cohort of individuals reporting mental health symptoms (n = 306) compared to mentally healthy controls (n = 164) using 16S rRNA sequencing. Mental health symptoms were evaluated using validated questionnaires and included depression, anxiety, and posttraumatic stress disorder (PTSD), with accompanying periodontal outcomes. Participants also indicated current or previous diagnoses of anxiety, depression, periodontitis, and gingivitis. Mental and periodontal health variables influenced the overall composition of the oral microbiome. PTSD symptoms correlated with a lower clr-transformed relative abundance of Haemophilus sputorum and a higher clr-transformed relative abundance of Prevotella histicola. The clr-transformed relative abundance of P. histicola was also positively associated with depressive scores and negatively associated with psychological quality of life. Anxiety disorder diagnosis was associated with a lower clr-transformed relative abundance of Neisseria elongate and a higher clr-transformed relative abundance of Oribacterium asaccharolyticum. A higher clr-transformed relative abundance of Shuttleworthia and lower clr-transformed relative abundance of Capnocytophaga were evident in those who reported a clinical periodontitis diagnosis. Higher Eggerthia and lower Haemophilus parainfluenzae clr-transformed relative abundances were associated with reported clinical periodontitis diagnoses and psychotherapeutic efficacy. Functional prediction analysis revealed a potential role for tryptophan metabolism/degradation in the oral-brain axis, which was confirmed by lower plasma serotonin levels across symptomatic groups. This study sheds light on the intricate interplay between oral microbiota, periodontal and mental health outcomes, and a potential role for tryptophan metabolism in the proposed oral-brain axis, emphasizing the need for further exploration to pave the way for novel therapeutic interventions and predicting therapeutic response.

Tumor-colonized Streptococcus mutans metabolically reprograms tumor microenvironment and promotes oral squamous cell carcinoma

BackgroundOral squamous cell carcinoma (OSCC) remains a major death cause in head and neck cancers, but the exact pathogenesis mechanisms of OSCC are largely unclear.ResultsSaliva derived from OSCC patients but not healthy controls (HCs) significantly promotes OSCC development and progression in rat models, and metabolomic analyses reveal saliva of OSCC patients but not HCs and OSCC tissues but not adjacent non-tumor tissues contain higher levels of kynurenic acid (KYNA). Furthermore, large amounts of Streptococcus mutans (S. mutans) colonize in OSCC tumor tissues, and such intratumoral S. mutans mediates KYNA overproductions via utilizing its protein antigen c (PAc). KYNA shifts the cellular types in the tumor microenvironment (TME) of OSCC and predominantly expedites the expansions of S100a8highS100a9high neutrophils to produce more interleukin 1β (IL-1β), which further expands neutrophils and induces CD8 + T cell exhaustion in TME and therefore promotes OSCC. Also, KYNA compromises the therapeutic effects of programmed cell death ligand 1 (PD-L1) and IL-1β blockades in oral carcinogenesis model. Moreover, KYNA-mediated immunosuppressive program and aryl hydrocarbon receptor (AHR) expression correlate with impaired anti-tumor immunity and poorer survival of OSCC patients.ConclusionsThus, aberration of oral microbiota and intratumoral colonization of specific oral bacterium such as S. mutans may increase the production of onco-metabolites, exacerbate the oral mucosal carcinogenesis, reprogram a highly immunosuppressive TME, and promote OSCC, highlighting the potential of interfering with oral microbiota and microbial metabolism for OSCC preventions and therapeutics.5ViVJ5sCbraGF_6Zi1UXojVideo

Microbiota, metabolic profiles and immune biomarkers in infants receiving formula with added bovine milk fat globule membrane: a randomized, controlled trial.

Few studies have evaluated the effects of milk fat globule membrane (MFGM) on microbiota and immune markers in early infant nutrition. In this double-blind randomized study, infants (7-18 days of age) received either bovine milk-based infant formula (Control) or similar formula with an added source (5 g/L) of bovine MFGM (INV-MFGM) for 60 days. A reference group received mother's own human milk over the same period (HM). Oral and stool samples were collected (Baseline and Day 60) to evaluate microbiota, immune markers, and metabolites. At Day 60, stool bacterial diversity and richness were higher in formula groups vs HM, as were Bifidobacterium bifidum and B. catenulatum abundance. Compared to HM, stool pH was higher in Control, while acetate, propionate, isovalerate, and total short- and branched-chain fatty acids were higher in INV-MFGM. Butyrate and lactate increased for INV-MFGM from baseline to Day 60. No group differences in oral microbiota or immune markers (α- and β-defensin, calprotectin, or sIgA) were detected, although sIgA increased over time in all study groups. Added bovine MFGM in infant formula modulated stool microbiota and short- and branched-chain fatty acids compared to human milk; changes were modest relative to control formula. Overall, distinct patterns of stool metabolites and microbiota development were observed based on early nutrition. ClinicalTrials.gov, identifier NCT04059666.

Oral Microbiota in Patients with Alzheimer’s Disease: A Systematic Review

Oral microorganisms have been found in the cerebral milieu, suggesting the involvement of oral microbiota in the onset and course of Alzheimer’s Disease (AD) through mechanisms such as amyloid-beta accumulation, tau phosphorylation and neuroinflammation. It is still uncertain whether and which oral bacteria are associated with AD. Therefore, the aim of this systematic review was to assess the current evidence for associations between oral microbiota and AD. A database search in Pubmed and Embase resulted in 623 hits. After removing duplicates, 437 papers remained. Of these, 13 papers passed the inclusion criteria and were included for quality/risk of bias assessment and data extraction. Analysis of these 13 studies revealed high heterogeneity in terms of sample size, age, study design and microbiological methods. Quality assessment using the MINORS criteria indicated reasonable to good quality across studies. As a result of the omission of two of the criteria, the quality results may have been biased. There is no conclusive evidence as to if and which oral microbiota are associated with AD since many conflicting results were reported. Although the overall quality of the studies was acceptable, the studies differed in study design and protocol. Further research is needed to clarify this association.

Unravelling the Role of Gut and Oral Microbiota in the Pediatric Population with Type 1 Diabetes Mellitus

Type 1 Diabetes Mellitus (T1DM) is a chronic autoimmune disease that results in the destruction of pancreatic β cells, leading to hyperglycaemia and the need for lifelong insulin therapy. Although genetic predisposition and environmental factors are considered key contributors to T1DM, the exact causes of the disease remain partially unclear. Recent evidence has focused on the relationship between the gut, the oral cavity, immune regulation, and systemic inflammation. In individuals with T1DM, changes in the gut and oral microbial composition are commonly observed, indicating that dysbiosis may contribute to immune dysregulation. Gut dysbiosis can influence the immune system through increased intestinal permeability, altered production of short chain fatty acids (SCFAs), and interactions with the mucosal immune system, potentially triggering the autoimmune response. Similarly, oral dysbiosis may contribute to the development of systemic inflammation and thus influence the progression of T1DM. A comprehensive understanding of these relationships is essential for the identification of biomarkers for early diagnosis and monitoring, as well as for the development of therapies aimed at restoring microbial balance. This review presents a synthesis of current research on the connection between T1DM and microbiome dysbiosis, with a focus on the gut and oral microbiomes in pediatric populations. It explores potential mechanisms by which microbial dysbiosis contributes to the pathogenesis of T1DM and examines the potential of microbiome-based therapies, including probiotics, prebiotics, synbiotics, and faecal microbiota transplantation (FMT). This complex relationship highlights the need for longitudinal studies to monitor microbiome changes over time, investigate causal relationships between specific microbial species and T1DM, and develop personalised medicine approaches.

Scoping Review of Microbiota Dysbiosis and Risk of Preeclampsia.

Limited studies have investigated the role of the microbiota in hypertensive disorders of pregnancy (HDP), particularly preeclampsia, which often results in preterm birth. We evaluated 23 studies that explored the relationship between gut, vaginal, oral, or placental microbiotas and HDP. Scopus, ProQuest Health Research Premium Collection, ProQuest Nursing & Allied Health Database, EBSCO, and Ovid were searched for relevant literature. Majority (18) of studies focused on the gut microbiota, and far fewer examined the oral cavity (3), vagina (3), and placenta (1). One study examined the gut, oral, and vaginal microbiotas. The consensus highlights a potential role for microbiota dysbiosis in preeclampsia and HDP. Especially in the third trimester, preeclampsia is associated with gut dysbiosis-deficient in beneficial species of Akkermansia, Bifidobacterium, and Coprococcus but enriched with pathogenic Campylobacterota and Candidatus Saccharibacteria, with low community α-diversity. Similarly, the preeclamptic vaginal and oral microbiotas are enriched with bacterial vaginosis and periodontal disease-associated species, respectively. The trend is also observed in the placenta, which is colonized by gastrointestinal, respiratory tract, and periodontitis-related pathogens. Consequently, a chronic proinflammatory state that adversely impacts placentation is implicated. These observations however require more mechanistic studies to establish the timing of the preceding immune dysfunction and any causality.

Oral Microbiota Variations in Psoriasis Patients Without Comorbidity.

Psoriasis is a chronic inflammatory skin disease, and its etiology is still unclear. There is increasing evidence suggesting that microorganisms may trigger psoriasis. However, the relationship between psoriasis and oral microbiota remains poorly understood. Our aim is to identify differences in the composition and diversity of the oral microbiota between patients with psoriasis and healthy controls, and to discover oral microbial markers for assessing the severity of psoriasis. This study recruited 20 psoriasis patients and 20healthy individuals, collecting their saliva to analyze the composition of the oral microbiota in psoriasis patients. We employed 16S rRNA sequencing technology and utilized various methods for oral microbiome analysis, including the Shannon Index, Gini-Simpson Index, Principal Coordinates Analysis (PCoA), non-metric multidimensional scaling (NMDS), Linear discriminant analysis Effect Size (LEfSe), Wilcoxon test, and Spearman's rank correlation. The results showed that the alpha diversity of oral microbiota was higher in psoriasis patients. The relative abundances of certain bacterial taxa differed between psoriasis and healthy individuals, including Prevotella, Prevotella 7 and Porphyromonas gingivalis, which are increased in psoriasis. We also found a positive correlation between Alloprevotella, Porphyromonas, and Neisseria with the severity of psoriasis, while Veillonella showed a negative correlation. In summary, this study found significant changes in the composition of the oral microbiota in patients with psoriasis. Some oral bacteria are associated with psoriasis severity. It provides a new perspective on the relationship between the oral microbiota and psoriasis.

Roles of oral and gut microbiota in acute myocardial infarction

IntroductionThe significance of oral/gut microbiota in acute myocardial infarction (AMI) has been increasingly appreciated. However, correlations between oral/gut microbiota and AMI parameter, as well as the key microbiota that may have a crucial function in this process, remain unclear. ObjectivesTo investigate the composition and structure of oral and gut microbiota associated with AMI and explore the roles of specific bacterial species in the progression of AMI. MethodsWe conducted a case-control study with 37 AMI patients and 36 controls. Oral and gut sample were collected and sequenced. Using correlation analysis, we combined bioinformatics data with AMI clinical parameters and obtained heatmaps of correlation coefficients. Additionally, we used antibiotics to eliminate the gut microbiota of C57BL/6J mice, followed by the transplantation of selected bacteria to verify the gut colonization of oral bacteria and their impact on AMI. ResultsThe component of oral and gut microbiota of AMI group showed significant alterations when compared to the control group. 17 salivary genera, 21 subgingival genera, and 8 gut genera in AMI group substantially differed from those in control group. Additionally, 19 genera from saliva, 19 genera from subgingival plaque, and 11 genera from feces substantially correlated with AMI clinical parameters. Orally administrated S.o (Streptococcus oralis subsp. dentisani), S.p (Streptococcus parasanguinis), and S.s (Streptococcus salivarius) were able to colonize in the gut and exacerbate myocardial infarction. ConclusionThere is a strong correlation between oral/gut microbiota and AMI. Streptococcus spp. is capable to transmit from oral to gut and exacerbate myocardial infarction in mice. Monitoring and control of specific oral microbiota may be an effective new strategy for improving the therapy of AMI.

Fusobacterium in oral bacterial flora relates with asymptomatic brain lesions

BackgroundSpecific bacterial species in the oral cavity contribute to cerebral hemorrhage and microbleeds. The relationship between oral bacterial flora and asymptomatic brain lesions (ABL) remains unclear. This study aimed to investigate this relationship in a healthy Japanese cohort. MethodsThis cross-sectional study included participants who underwent health examinations at our Brain Dock facility between October 2020 and March 2021. The oral microbiomes of participants with and without ABL were compared using magnetic resonance imaging. To extensively assess the oral bacterial flora, the differences in genes and species compositions between the ABL and noBL (without brain lesions) groups were statistically evaluated via extensive analysis using 16S rRNA gene-based cloning. ResultsAmong 143 patients, 48.3 % had ABL. In the univariate analyses, Fusobacterium and Leptotrichia were associated with ABL (P = 0.017 and P < 0.001, respectively). In the adjusted models, Fusobacterium was associated with ABL (P = 0.006). In an intergroup comparison of seven Fusobacterium species, F. nucleatum, F. naviforme, and F. canifelinum were associated with ABL (P < 0.001, P = 0.002, P < 0.001). ConclusionsThe elevation of Fusobacterium in the ABL indicates the importance of the microbiome in the oral cavity as a factor in inducing cerebral small-vessel disease in healthy individuals, whose preventive approach might have an impact on therapeutic applications.

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.

Multiomics Analysis Reveals Significant Disparities in the Oral Microbiota and Metabolites Between Pregnant Women with and without Periodontitis.

Our study investigated the disparities and correlations between oral microbiota and metabolites in pregnant patients with and without periodontitis. Subgingival plaque samples from all subjects were collected for shotgun metagenomic sequencing and broad-target metabolomics analysis. Forty pathogens, including Porphyromonas gingivalis, Fusobacterium nucleatum, Eubacterium saphenum, Gemella morbillorum, Tannerella forsythia, Streptococcus anginosus group, Selenomonas sputigena etc, were significantly enriched in pregnant patients with periodontitis (PPP). Conversely, symbiotic species such as Morococcus cerebrosus, Streptococcus vestibularis, S. salivarius, S. mitis, and S. pneumoniae were significantly more abundant in healthy controls (HCs). A total of 87 predicted functional modules (PFMs) exhibited significant differences between the two groups; eight PFMs showed high enrichment in PPP with involvement of PPP-enriched species within these pathways. The remaining 79 PFMs encompassing ribonucleotide biosynthesis, carbohydrate, and amino acid metabolism were highly abundant in HCs. For oral microbial metabolome, a total of 105 metabolites related to 150 KEGG pathways displayed significant differences between the two groups. Pathways such as pyruvate metabolism, folate biosynthesis, vascular smooth muscle contraction, and AMPK/mTOR signaling pathway along with their associated metabolites were found to be enriched in PPP, while carbohydrate metabolism predominated among HCs. Spearman's rank correlation analysis revealed significant positive associations between species enriched in PPP and metabolites enriched in PPP, but significant negative associations between species enriched in PPP and metabolites enriched in HCs. Our findings provide potential biomarkers for distinguishing periodontitis during pregnancy while offering valuable insights into mechanisms exploration and clinical intervention.

Pilots, Astronauts, and the Aerospace Microbiota: A Narrative Review of Occupational Impact.

The human microbiota plays a crucial role in maintaining health and preventing disease; however, the effects of occupational exposureon the microbiota of aircrew and astronauts are not fully understood. This narrative review aims to synthesize the current knowledge on microbiota alterations in aerospace medicine, assess the potential of probiotics as a countermeasure, and identify key gaps that warrant further research. The references were identified through searchingPubMed for English articles published between 2010 and 2024, using keywords related to microbiota, probiotics, aviation, spaceflight, pilots, and astronauts. Additionally, the bibliographies of relevant papers were reviewed. Studies in aerospace medicine were selected based on their focus on the occupational impacton microbiota and the use of probiotics in this context. For aircrew, initial studies indicatea decrease in beneficial gut bacteria, suggesting that probiotics could enhance gastrointestinal health, immunity, and overall well-being. However, unsupervised use of probiotics carries potential risks. Conversely, spaceflight induces significant changes in the gut, skin, oral, and nasal microbiota of astronauts, characterized by altered diversity and abundanceof specific microbial taxa. These changes include a relative decrease in the abundance of beneficial gut bacteria, an increase in opportunistic pathogens, and evidence of microbial transfer between astronauts and spacecraft surfaces. While simulated space studies suggest the potential for probiotics to mitigate dysbiosis, direct testing done during actual spaceflight is lacking. The observed microbiota changes during spaceflight are associated with various health implications, including alterations in metabolic pathways and interactions between the microbial metabolic capabilities and the host's metabolism. In conclusion, this review highlights the profound impact of spaceflight on astronaut microbiota and the promising role of probiotics as an intervention in both space and aviation medicine. However, significant research gaps remain. These include elucidating the functional implications of microbial shifts, developing personalized countermeasures, and validating the efficacy of probiotics during spaceflight. Future studies should leverage advanced tools such as metagenomic analysis and longitudinal tracking of astronaut health to inform targeted interventions that support the well-being of aerospace personnel. Integrating data across different sites of the body and missions, facilitated by resources like the Space Omics and Medical Atlas (SOMA), can help identify consistent microbial changes induced by the unique occupational conditions of spaceflight and aviation. This integrated approach will be crucial for developing effective microbiota-based countermeasures to mitigate the occupational health risks associated with space and aviation.

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

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.