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

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

IMPROVEMENT OF THE METHODOLOGY OF BIOMATERIAL COLLECTION FOR THE DIAGNOSIS OF THE ORAL CAVITY MUCOSA DISEASES.

Aim - to improve the methodology for collecting material from lesions of the oral mucosa for exfoliative cytological examination. A group of patients diagnosed with B37.0 Candida stomatitis was examined. To clarify the diagnosis, various methods of collecting biological material from the tongue of patients were used, namely, the method using a cytobrush with subsequent fixation of cytological material on a slide. The microbiota of the back of the tongue was analyzed in 12 patients with glossitis and 12 healthy subjects (the control group). The microscopic method of research was used - using an immersion microscope MICROmed@XS-3330, and the morphological and tinctorial properties of microorganisms were determined. In ten fields of view, the number of leukocytes, the nature of epithelial cells, and the presence of various microorganisms were detected and counted. A comparison of the quality of the use of the microscope method for the study of the tongue microbiota of patients with candidal glossitis was performed under the conditions of taking pathological material using a dental scalpel and an oral cytobrush. For a reasonable interpretation of the results and determination of their significance, a statistical analysis was performed to determine the frequency of detection of microorganisms in patients with glossitis and healthy subjects, depending on the nature of the material taken from the back of the tongue using a dental scalpel or cytobrush. The studies showed that the etiologic structure of glossitis pathogens was dominated by Candida yeast-like fungi, but cases of leptotrichosis aetiology were observed (16.7%). Monococci and gram-negative monobacteria were detected in all studied groups. An increase in the diversity of microorganisms was found when the material was taken with a cytobrush. The microbiota of all subjects differed depending on the type of instrument used for sampling. Thus, in the group of healthy individuals, the interdental brush helped to detect twice as many streptococci as a scalpel. In patients with candidiasis, a brush biopsy showed a 2.7-fold increase in gram-positive diplococci, twice as many streptococci and gram-positive bacilli, three times as many staphylococci, 2.25 times as many clusterforming gram-negative cocci, and 2.3 times as many gram-negative diplococci. A significant increase in the diversity of microorganisms was observed with the cytobrush compared to the use of a dental scalpel. In patients with glossitis, the accumulation of keratinized epithelial cells was significantly higher compared to the presence of young cells in healthy subjects, regardless of the method of sampling.

Coptidis rhizoma extract alleviates oropharyngeal candidiasis by gC1qR-EGFR/ERK/c-fos axis-induced endocytosis of oral epithelial cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Coptidis rhizoma, first recorded in the "Shen Nong's Herbal Classic", is one of the traditional Chinese medicine (TCM) used to treat infectious diseases, with reputed effectiveness against oropharyngeal candidiasis (OPC). Studies have demonstrated the inhibitory properties of C. rhizoma (CRE) against Candida albicans, yet there is limited information available regarding its treatment mechanism for OPC. AIM OF THE STUDY: Our previous research has suggested that CRE can prevent the formation of C. albicans hyphae and their invasion of the oral mucosa, thereby exerting a therapeutic effect on OPC. Nevertheless, the precise therapeutic mechanisms remain incompletely understood. Previous studies have revealed that a receptor for globular heads of C1q (gC1qR), a crucial co-receptor of the epidermal growth factor receptor (EGFR), facilitates the EGFR-mediated internalization of C. albicans. Therefore, this study aims to investigate the potential mechanism of action of CRE and its primary component, berberine (BBR), in treating OPC by exploring their effects on the gC1qR-EGFR co-receptor. MATERIALS AND METHODS: To identify the chemical components of CRE, we utilized Ultra-high performance liquid chromatography in conjunction with quadrupole time-of-flight mass spectrometry (UPLC-Q/TOF-MSE), revealing the presence of at least 18 distinct components. To observe the therapeutic effects of CRE on OPC at the animal level, we employed hematoxylin and eosin staining, periodic acid-Schiff staining, scanning electron microscopy, and fungal load detection. Subsequently, we evaluated the anti-inflammatory properties of CRE and its main component, BBR, in treating OPC. This was achieved through enzyme-linked immunosorbent assay (ELISA) both at the animal and cellular levels. Additionally, we assessed the ability of C. albicans to disrupt the epithelial barrier of FaDu cells by studying the protective effects of BBR on the fusion barrier using the transwell assay. To further explore the underlying mechanisms, we analyzed the effects of BBR on the gC1qR-EGFR/extracellular signal-regulated kinase/c-Fos signaling pathway at the cellular level using qRT-PCR, western blotting, and immunofluorescence. Furthermore, we validated the effects of BBR on the gC1qR-EGFR co-receptor through ELISA, qRT-PCR, and western blotting. Finally, to confirm the outcomes observed at the cellular level, we validated the impact of CRE on the gC1qR-EGFR co-receptor in vivo using qRT-PCR, western blotting, and immunofluorescence. These comprehensive methods allowed us to gain a deeper understanding of the therapeutic mechanisms of CRE and BBR in treating OPC. RESULTS: Our findings indicate that CRE and its primary component, BBR, effectively alleviated the symptoms of OPC by modulating the gC1qR-EGFR co-receptor. The chemical composition of CRE and BBR was accurately identified using UPLC-Q/TOF-MSE. The gC1qR-EGFR co-receptor plays a crucial role in regulating downstream signaling pathways, emerging as a potential therapeutic target for OPC treatment. Through both in vitro and in vivo experiments, we explored the therapeutic potential of CRE and BBR in OPC. Additionally, we employed overexpression and silencing techniques to confirm that BBR can indeed influence the gC1qR-EGFR co-receptor and regulate the gC1qR-EGFR/extracellular signal-regulated kinase (ERK)/c-Fos signaling pathway, leading to improved OPC outcomes. Furthermore, the significance of CRE's effect on the gC1qR-EGFR co-receptor was validated in vivo. CONCLUSION: Our study demonstrates that CRE and its main component, BBR, can effectively alleviate OPC symptoms by targeting the gC1qR-EGFR heterodimer receptor. This discovery offers a promising new therapeutic approach for the treatment of OPC.

Exploring the Oral Manifestations of Tuberculosis: A Comprehensive Analysis of Prevalence and Clinicopathological Characteristics of Oral Lesions.

BACKGROUND: The study aimed to report all cases of oral tuberculosis (TB), a rare manifestation of the fatal infectious disease primarily affecting the pulmonary system. The report also evaluated the clinicopathological characteristics of oral TB lesions. METHODS: A total of 25 patients who presented with oral lesions between August 2013 and August 2023 were diagnosed with TB through surgical biopsy despite having no prior history of the disease. Their clinical symptoms, auxiliary examinations, treatments, and outcomes were recorded and analyzed for further study. RESULTS: In a study of 25 patients with oral TB, all patients were found to have the disease, with 16 males and 9 females affected. The gender distribution was skewed toward males, with a 1.77 male-to-female ratio. Twelve cases of the affected sites were reported in the mandible, six cases in the buccal mucosa, four in the lips, two in the gingiva, and one in the tongue. The age range of affected patients was 0-70 years old, and all lesions were indicative of primary TB. The appearance of the affected mucosa varied, with ulceration and swelling being the most common manifestations. CONCLUSION: Patients who present with oral ulcerations and swellings should be evaluated for the possibility of TB. To confirm and differentiate this condition from other diseases, obtaining a biopsy specimen for histological analysis and performing acid-fast stains and cultures is recommended. These tests will enable a precise diagnosis and guide appropriate treatment.

Prospective, multi-centric, international, single-arm, cohort study to assess a synthetic polyamide suture material in oral surgery to close the mucosa - MUCODA study.

OBJECTIVES: The aim was to collect different clinical parameters systematically and proactively regarding safety, effectiveness, and performance of a nylon monofilament suture under routine clinical practice for oral surgery. METHODS: The study design was prospective, bicentric, international, single-armed, and observational. A non-absorbable suture was applied to close the mucosa after different dental surgical interventions. Main objective was the incidence of combined postoperative complications until suture removal. The 95 % Confidence Interval (Agresti-Coull method) was used to prove the non-inferiority with a pre-specified upper margin of 21.9 %. Secondary variables were intraoperative suture handling, patient pain and satisfaction, wound healing, aesthetic appearance, and bacterial contamination. RESULTS: 105 patients were enrolled. Complication rate was low (1.9 %), 2 swellings occurred. Pain was present for 1.61 days ± 1.42 after various dental interventions with an average pain level of 20.98 ± 22.60 (VAS). Patients with impacted third molar extraction showed the longest pain duration (6 days) combined with the highest mean pain level of 35.33 ± 30.45 (VAS). Intraoperative suture handling was very good to excellent. Suture removal was done after an average duration of 7.56 ± 2.09 days. Patient's satisfaction was high, and an excellent wound healing was reported by the dentists. Aesthetic appearance only performed in implant patients was rated by oral surgeons with an average of 96.19 ± 3.79 points [min. 80 - max. 100] at 5 months postoperatively. Thread bacterial analysis showed that F. nucleatum was the most present species. CONCLUSIONS: Our findings indicate that the non-absorbable, nylon-based monofilament suture used is safe and quite suitable for oral mucosal closure after various dental surgical interventions such as tooth extraction, implant placement and impacted third molar extraction. CLINICAL SIGNIFICANCE: This study showed the safe use of a non-absorbable, nylon-based monofilament suture for different oral surgical interventions under daily routine clinical practice.

RFX transcription factor in the human-associated yeast Candida albicans regulates adhesion to oral epithelium.

Adhesion to mucosal surfaces is a critical step in many bacterial and fungal infections. Here, using a mouse model of oral infection by the human fungal pathobiont Candida albicans, we report the identification of a novel regulator of C. albicans adhesion to the oral mucosa. The regulator is a member of the regulatory factor X (RFX) family of transcription factors, which control cellular processes ranging from genome integrity in model yeasts to tissue differentiation in vertebrates. Mice infected with the C. albicans rfx1 deletion mutant displayed increased fungal burden in tongues compared to animals infected with the reference strain. High-resolution imaging revealed RFX1 transcripts being expressed by C. albicans cells during infection. Concomitant with the increase in fungal burden, the rfx1 mutant elicited an enhanced innate immune response. Transcriptome analyses uncovered HWP1, a gene encoding an adhesion protein that mediates covalent attachment to buccal cells, as a major RFX1-regulated locus. Consistent with this result, we establish that C. albicans adhesion to oral cells is modulated by RFX1 in an HWP1-dependent manner. Our findings expand the repertoire of biological processes controlled by the RFX family and illustrate a mechanism whereby C. albicans can adjust adhesion to the oral epithelium.

Preliminary analysis of mucosal and salivary bacterial communities in oral lichen planus.

OBJECTIVE: To characterize the bacterial community from different oral niches (buccal mucosa and saliva) in oral lichen planus (OLP) patients. SUBJECTS AND METHODS: This preliminary study analyzed site-specific (mucosa and saliva) microbial landscape of 20 OLP patients and 10 healthy controls. RESULTS: The microbial diversity was similar between OLP patients and healthy controls in both salivary and mucosal communities. However, the topological properties of co-occurrence networks of salivary and mucosal microbiome were different between healthy controls and OLP patients. SparCC analysis inferred three and five keystone taxa in the salivary and mucosal microbial networks of healthy controls, respectively. However, in the salivary and mucosal bacterial networks of OLP patients, only one hub OTU and three OTUs were identified as keystone taxa, respectively. In addition, analysis of community cohesion revealed that mucosal microbial community in OLP patients had lower stability than that in healthy controls. In final, correlation assay showed that the clinical severity of OLP was positively associated with the relative abundance of Rothia in saliva but negatively associated with that of Porphyromonas on mucosa. CONCLUSIONS: The salivary and mucosal bacterial communities of OLP patients differ in terms of composition, the genera associated with OLP severity, and co-occurrence patterns.

The IL-20RB receptor and the IL-20 signaling pathway in regulating host defense in oral mucosal candidiasis.

Pseudomembranous candidiasis (thrush), erythematous candidiasis, and fungal esophagitis are infections of the barrier mucosa of the upper gastrointestinal tract. The majority of these infections are caused by Candida albicans, an opportunistic fungal pathogen that frequently exists as a harmless commensal on mucosal surfaces lining the gastrointestinal tract. Oral infections are initiated in the superficial stratified squamous epithelium, in which keratinocytes are the most abundant host cells and are the initial points of contact with C. albicans present in saliva. Intrinsic features of oral keratinocytes are likely to play important roles in host defense and tissue homeostasis in oral candidiasis. One understudied pathway that may be important for modulating oral candidiasis is the IL-20 cytokine signaling pathway that employs keratinocyte IL-20RB receptors as ligands for IL-19, IL-20, and IL-24. We report that production of human oral keratinocyte il24 mRNA and protein are stimulated during co-culture with C. albicans. To test the role of the IL-20 family signaling pathway in oral candidiasis, Il20rb-/- mice (lacking the IL-20RB receptor) were compared to wild-type mice in a murine model of oropharyngeal candidiasis. Fungal burdens and percent loss in body weight were determined. Despite comparable fungal burdens, the Il20rb-/- mice exhibited less weight loss over the course of their infection compared to the B6 mice, suggestive of reduced overall disease consequences in the mutant mice. Interference with IL-20 family cytokine signaling may be useful for augmenting the ability of the host to defend itself against pathogens.

Commensal oral microbiota impacts ulcerative oral mucositis clinical course in allogeneic stem cell transplant recipients.

Oral mucositis (OM) is a complex acute cytotoxicity of antineoplastic treatment that affects 40-85% of patients undergoing hematopoietic stem-cell transplantation. OM is associated with prolonged hospitalization, increased extensive pharmacotherapy, need for parenteral nutrition, and elevated treatment costs. As OM onset relates to the mucosal microenvironment status, with a particular role for microbiota-driven inflammation, we aimed to investigate whether the oral mucosa microbiota was associated with the clinical course of OM in patients undergoing allogeneic hematopoietic stem-cell transplantation. We collected oral mucosa samples from 30 patients and analyzed the oral mucosa microbiota by 16S rRNA sequencing. A total of 13 patients (43%) developed ulcerative OM. We observed that specific taxa were associated with oral mucositis grade and time to oral mucositis healing. Porphyromonas relative abundance at preconditioning was positively correlated with ulcerative OM grade (Spearman ρ = 0.61, P = 0.028) and higher Lactobacillus relative abundance at ulcerative OM onset was associated with shortened ulcerative OM duration (P = 0.032). Additionally, we generated a machine-learning-based bacterial signature that uses pre-treatment microbial profiles to predict whether a patient will develop OM during treatment. Our findings suggest that further research should focus on host-microbiome interactions to better prevent and treat OM.

A gut-oral microbiome-driven axis controls oropharyngeal candidiasis through retinoic acid.

A side effect of antibiotics is outgrowth of the opportunistic fungus Candida albicans in the oropharynx (oropharyngeal candidiasis, OPC). IL-17 signaling is vital for immunity to OPC, but how the microbiome impacts antifungal immunity is not well understood. Mice in standard specific pathogen-free (SPF) conditions are resistant to OPC, whereas we show that germ-free (GF) or antibiotic-treated mice are susceptible. Oral type 17 cells and IL-17-dependent responses were impaired in antibiotic-treated and GF mice. Susceptibility could be rescued in GF mice by mono-colonization with segmented filamentous bacterium (SFB), an intestine-specific constituent of the microbiota. SFB protection was accompanied by restoration of oral IL-17+CD4+ T cells and gene signatures characteristic of IL-17 signaling. Additionally, RNA-Seq revealed induction of genes in the retinoic acid (RA) and RA receptor-α (RARα) pathway. Administration of RA rescued immunity to OPC in microbiome-depleted or GF mice, while RAR inhibition caused susceptibility in immunocompetent animals. Surprisingly, immunity to OPC was independent of serum amyloids. Moreover, RAR inhibition did not alter oral type 17 cytokine levels. Thus, mono-colonization with a component of the intestinal microflora confers protection against OPC by type 17 and RA/RARα, which act in parallel to promote antifungal immunity. In principle, manipulation of the microbiome could be harnessed to maintain antifungal immunity.

Receptor-kinase EGFR-MAPK adaptor proteins mediate the epithelial response to Candida albicans via the cytolytic peptide toxin, candidalysin.

Candida albicans (C. albicans) is a dimorphic commensal human fungal pathogen that can cause severe oropharyngeal candidiasis (oral thrush) in susceptible hosts. During invasive infection, C. albicans hyphae invade oral epithelial cells (OECs) and secrete candidalysin, a pore-forming cytolytic peptide that is required for C. albicans pathogenesis at mucosal surfaces. Candidalysin is produced in the hyphal invasion pocket and triggers cell damage responses in OECs. Candidalysin also activates multiple MAPK-based signaling events that collectively drive the production of downstream inflammatory mediators that coordinate downstream innate and adaptive immune responses. The activities of candidalysin are dependent on signaling through the epidermal growth factor receptor (EGFR). Here, we interrogated known EGFR-MAPK signaling intermediates for their roles mediating the OEC response to C. albicans infection. Using RNA silencing and pharmacological inhibition, we identified five key adaptors, including growth factor receptor-bound protein 2 (Grb2), Grb2-associated binding protein 1 (Gab1), Src homology and collagen (Shc), SH2-containing protein tyrosine phosphatase-2 (Shp2), and casitas B-lineage lymphoma (c-Cbl). We determined that all of these signaling effectors were inducibly phosphorylated in response to C. albicans. These phosphorylation events occurred in a candidalysin-dependent manner and additionally required EGFR phosphorylation, matrix metalloproteinases (MMPs), and cellular calcium flux to activate a complete OEC response to fungal infection. Of these, Gab1, Grb2, and Shp2 were the dominant drivers of ERK1/2 activation and the subsequent production of downstream innate-acting cytokines. Together, these results identify the key adaptor proteins that drive the EGFR signaling mechanisms that underlie oral epithelial responses to C. albicans.

INTERDEPENDENCE OF THE MICROBIOCENOSE COMPOSITION OF BIOPELLICLE AND THE SEVERITY DEGREE OF CHANGES IN THE MUCOSA OF THE GUMS AFTER TEN WEEKS OF EXPERIMENTAL OPIOID EXPOSURE.

OBJECTIVE: The aim: To study the relationship between the degree severity of changes in the tunica mucosa of the rats gums and the composition of the microbiota of tooth surface in the gingival margin under the ten-week action of the opioid. PATIENTS AND METHODS: Materials and methods: The study was performed on 34 male rats, weighing 160 - 255 g, aged 4.5 - 7 months. Animals were administered nalbuphine for 10 weeks, gradually increasing the dose (0.212 - 0.283 mg/kg). The research of the bacterial from the microbiotope of tooth surface in the gingival margin of rats was performed using statistical analysis of quantitative results. RESULTS: Results: The 4 stages of development of the pathological process and changes in the qualitative and quantitative composition of the microbiocenosis in the gingival margin of the oral mucosa are determined. Depending on the severity of pathological changes in the mucous membrane of the gums of rats under the long-term action of the opioid, a significant increase in the quantitative indicators of bacterial species of pathogenic and opportunistic microbiota at degree IV of the process compared with degree I. The appearance of potential pathogens of purulent-inflammatory processes - Klebsiella and Pseudomonas aeruginosa was noted. CONCLUSION: Conclusions: The relationship between the quantitative and qualitative characteristics of the microbiocenosis of tooth surface in the gingival margin and the severity of changes in the mucous membrane of the of rats gums under the ten-week action of the opioid was determined, indicating bacterial associations of dental biopellicle as an etiological factor.

[The study of microbiota in patients with bullous lesions of the oral mucosa]. / Izuchenie mikrobioty slizistoi obolochki rta u patsientov s bulleznymi porazheniyami.

THE AIM OF THE STUDY: The study by the method of tissue polymerase chain reaction of the species composition of the microbiota of lesions of the oral mucosa in patients with bullous lesions. MATERIAL AND METHODS: Biopsy specimens of the oral mucosa of 51 patients were studied by the polymerase chain reaction method, of which 14 patients with pemphigus vulgaris, 17 patients with pemphigoid bullosa, and 20 patients with the bullous form of ruber lichen planus. 4 types of microorganisms have been identified - Fusobacterium, Streptococcus pneumoniae, Candida albicans, Ureaplasma spp. and viruses - Human Papillomavirus 16, Epstein-Barr virus and Citomegalovirus. RESULTS: In the study of the microbiota of bullous lesions, associations of microorganisms and viruses were established in a significant number of cases. Associations of Str.pneumoniae and C. albicans were quite common in patients with pemphigus vulgaris in 26.3%, pemphigoid bullosa in 20.0%, and in patients with the bullous form of ruber lichen planus in 14.3% of cases. In patients with pemphigus vulgaris, the association of Str.pneumoniae, C. albicans and EBV was noted in 31.6% of cases. In patients with the bullous form of ruber lichen planus in a high percentage of cases (28.6%), the associations of Str. pneumoniae, EBV and CMV. CONCLUSION: Identification at earlier stages of management of patients with bullous lesions Str. pneumoniae, Candida albicans, and Fusobacterium associated with herpes viruses should be regarded as one of the triggering mechanisms of an autoimmune conflict, which subsequently causes a specific clinical picture of these diseases.

Candida albicans commensalism in the oral mucosa is favoured by limited virulence and metabolic adaptation.

As part of the human microbiota, the fungus Candida albicans colonizes the oral cavity and other mucosal surfaces of the human body. Commensalism is tightly controlled by complex interactions of the fungus and the host to preclude fungal elimination but also fungal overgrowth and invasion, which can result in disease. As such, defects in antifungal T cell immunity render individuals susceptible to oral thrush due to interrupted immunosurveillance of the oral mucosa. The factors that promote commensalism and ensure persistence of C. albicans in a fully immunocompetent host remain less clear. Using an experimental model of C. albicans oral colonization in mice we explored fungal determinants of commensalism in the oral cavity. Transcript profiling of the oral isolate 101 in the murine tongue tissue revealed a characteristic metabolic profile tailored to the nutrient poor conditions in the stratum corneum of the epithelium where the fungus resides. Metabolic adaptation of isolate 101 was also reflected in enhanced nutrient acquisition when grown on oral mucosa substrates. Persistent colonization of the oral mucosa by C. albicans also correlated inversely with the capacity of the fungus to induce epithelial cell damage and to elicit an inflammatory response. Here we show that these immune evasive properties of isolate 101 are explained by a strong attenuation of a number of virulence genes, including those linked to filamentation. De-repression of the hyphal program by deletion or conditional repression of NRG1 abolished the commensal behaviour of isolate 101, thereby establishing a central role of this factor in the commensal lifestyle of C. albicans in the oral niche of the host.

Oral streptococci subvert the host innate immune response through hydrogen peroxide.

In periodontal health, oral streptococci constitute up to 80% of the plaque biofilm. Yet, destructive inflammatory events of the periodontium are rare. This observation suggests that oral streptococci may possess mechanisms to co-exist with the host. However, the mechanisms employed by oral streptococci to modulate the innate immune response have not been well studied. One of the key virulence factors produced by oral streptococci is hydrogen peroxide (H2O2). In mammalian cells, H2O2 triggers the activation of nuclear factor erythroid 2-related factor 2 (Nrf2), a key pathway mediating antioxidant defence. This study aimed to determine (1) if H2O2 producing oral streptococci activated the Nrf2 pathway in macrophages, and (2) if the activation of Nrf2 influenced the innate immune response. We found that oral streptococci downregulated the innate immune response in a H2O2 dependent manner through the activation of the Nrf2. The activation of the Nrf2 signalling pathway led to the inhibition of nuclear factor kappa-light-chain-enhancer of activated B cells (NFĸB), the key transcription factor regulating pro-inflammatory response. This study showed for the first time that oral streptococci are unlikely passive bystanders but could play an active role in the maintenance of periodontal health by preventing overt inflammation.

Armed to the Teeth-The Oral Mucosa Immunity System and Microbiota.

The oral cavity is inhabited by a wide spectrum of microbial species, and their colonization is mostly based on commensalism. These microbes are part of the normal oral flora, but there are also opportunistic species that can cause oral and systemic diseases. Although there is a strong exposure to various microorganisms, the oral mucosa reduces the colonization of microorganisms with high rotation and secretion of various types of cytokines and antimicrobial proteins such as defensins. In some circumstances, the imbalance between normal oral flora and pathogenic flora may lead to a change in the ratio of commensalism to parasitism. Healthy oral mucosa has many important functions. Thanks to its integrity, it is impermeable to most microorganisms and constitutes a mechanical barrier against their penetration into tissues. Our study aims to present the role and composition of the oral cavity microbiota as well as defense mechanisms within the oral mucosa which allow for maintaining a balance between such numerous species of microorganisms. We highlight the specific aspects of the oral mucosa protecting barrier and discuss up-to-date information on the immune cell system that ensures microbiota balance. This study presents the latest data on specific tissue stimuli in the regulation of the immune system with particular emphasis on the resistance of the gingival barrier. Despite advances in understanding the mechanisms regulating the balance on the microorganism/host axis, more research is still needed on how the combination of these diverse signals is involved in the regulation of immunity at the oral mucosa barrier.

Oral and gastric microbiome in relation to gastric intestinal metaplasia.

Evidence suggests that Helicobacter pylori plays a role in gastric cancer (GC) initiation. However, epidemiologic studies on the specific role of other bacteria in the development of GC are lacking. We conducted a case-control study of 89 cases with gastric intestinal metaplasia (IM) and 89 matched controls who underwent upper gastrointestinal endoscopy at three sites affiliated with NYU Langone Health. We performed shotgun metagenomic sequencing using oral wash samples from 89 case-control pairs and antral mucosal brushing samples from 55 case-control pairs. We examined the associations of relative abundances of bacterial taxa and functional pathways with IM using conditional logistic regression with and without elastic-net penalty. Compared with controls, oral species Peptostreptococcus stomatis, Johnsonella ignava, Neisseria elongata and Neisseria flavescens were enriched in cases (odds ratios [ORs] = 1.29-1.50, P = .004-.01) while Lactobacillus gasseri, Streptococcus mutans, S parasanguinis and S sanguinis were under-represented (ORs = 0.66-0.76, P = .006-.042) in cases. Species J ignava and Filifactor alocis in the gastric microbiota were enriched (ORs = 3.27 and 1.43, P = .005 and .035, respectively), while S mutans, S parasanguinis and S sanguinis were under-represented (ORs = 0.61-0.75, P = .024-.046), in cases compared with controls. The lipopolysaccharide and ubiquinol biosynthesis pathways were more abundant in IM, while the sugar degradation pathways were under-represented in IM. The findings suggest potential roles of certain oral and gastric microbiota, which are correlated with regulation of pathways associated with inflammation, in the development of gastric precancerous lesions.

Compositional profile of mucosal bacteriome of smokers and smokeless tobacco users.

INTRODUCTION: Smoked, and especially smokeless, tobacco are major causes of oral cancer globally. Here, we examine the oral bacteriome of smokers and of smokeless tobacco users, in comparison to healthy controls, using 16S rRNA gene sequencing. METHODS: Oral swab samples were collected from smokers, smokeless tobacco users, and healthy controls (n = 44). Microbial DNA was extracted and the 16S rRNA gene profiled using the Illumina MiSeq platform. Sequencing reads were processed using DADA2, and taxonomical classification was performed using the phylogenetic placement method. Differentially abundant taxa were identified using DESeq2, while functional metagenomes based on KEGG orthology abundance were inferred using LIMMA. RESULTS: A significantly higher microbial diversity was observed in smokeless tobacco users and smokers relative to controls (P < 0.05). Compositional differences in microbial communities were observed in all comparisons with healthy controls (PERMANOVA P < 0.05) but not between smokers and smokeless tobacco users. Levels of Fusobacterium spp., Saccharibacterium spp., and members of Shuttleworthia were elevated in smokers when compared to controls (BH adj P < 0.01). In addition, the relative abundance of three bacterial taxa belonging to genera Fusobacterium spp., Catonella, and Fretibacterium spp. was significantly increased in smokeless tobacco users relative to controls (BH adj P < 0.01). Major functional pathways significantly increased in smokeless tobacco users relative to both controls, and smokers were similar and involved amino acid metabolism including glutamate and aspartate biosynthesis and degradation (log FC > 1.5; BH adj P < 0.01). CONCLUSIONS: A distinct taxonomic and functional profile of oral microbiome in smokers and smokeless tobacco users as compared to healthy controls implicates a significant role of microbes and their metabolites in diseases associated with tobacco use including oral cancer. CLINICAL RELEVANCE: Future efforts in preventive, diagnostic, curative, and prognostic strategies for diseases associated with tobacco use in smokers and smokeless tobacco users could incorporate the oral microbiome.

Prevention of the proliferation of oral pathogens due to prolonged mask use based on α-cyclodextrin and hydroxytyrosol mouthwash.

OBJECTIVE: Face masks help contain the aerosol-mediated transmission of infectious viral particles released from individuals via cough and sneezes. However, the prolonged use of face masks has raised concerns regarding oral hygiene. Here, we present a mouthwash formulation based on α-cyclodextrin and hydroxytyrosol that can maintain healthy oral microbiota. MATERIALS AND METHODS: We isolated and cultured Candida albicans, Staphylococcus aureus, and a mix of Streptococcus sp., Staphylococcus sp. and Neisseria sp. from oral and throat swabs. The microorganisms were cultured in a standard medium with or without the mouthwash. To evaluate the effect of the mouthwash on the oral microbiota, the DNA from the saliva of 3 volunteers that used the mouthwash was extracted. Then, the DNA was amplified using primer pairs specific for bacterial and fungal DNA. Twelve further volunteers were offered to use the mouthwash and a questionnaire was submitted to them to assess the possible beneficial effects of mouthwash on halitosis and other oral disturbances. RESULTS: The bacteria and fungi cultured in media containing the mouthwash showed a growth reduction ranging from 20 to 80%. The PCR amplification of fungal and bacterial DNA extracted from volunteers that used the mouthwash showed a reduction of both bacteria and fungi. Volunteers that used the mouthwash reported a tendency towards a reduction of halitosis, gingival and mouth inflammation, and dry mouth. CONCLUSIONS: The use of a mouthwash containing α-cyclodextrin and hydroxytyrosol is not aggressive against oral mucosa; it is safe and effective to reduce the bacterial and fungal load due to the continuous use of face masks.