[Analysis of saliva and intestinal microbial community in children with severe caries based on 16S rDNA high-throughput sequencing technology].

PURPOSE: The characteristics of saliva and intestinal microbial community in children with high caries and no caries were analyzed by 16S rDNA high-throughput sequencing. METHODS: Among 431 children aged 3-5 years old in Zunyi City who were investigated previously by our team, 25 children in the high caries group and the same in the caries-free group were selected for fecal and saliva samples. 16S rDNA high-throughput sequencing was used to analyze the bacterial flora structure of the samples and identify the species with different relative abundance at the species level. SPSS 18.0 software package was used for data analysis. RESULTS: The diversity of intestinal flora in the high caries group was higher than that in the caries-free group, and the difference was statistically significant(P＜0.05). The diversity of salivary flora in the high caries group was more than that in the caries-free group, with no significant difference(P＞0.05). At phylum level,there was no significant difference in intestinal and salivary flora between children with high caries and children without caries. At gene level, Blautia, [Eubacterium] hallii group and [Eubacterium] eligens group in the intestine of caries-free group were significantly higher than those of high caries group(P＜0.05), while Parasutterella and Christensenellaceae R-7 group were significantly lower than those of high caries group(P＜0.05). At gene level, Peptostreptococcus in saliva of caries-free group was significantly higher than that in high caries group(P＜0.05). Dialister, Kingella, Escherichia-Shigella and Treponema in saliva of caries-free group were significantly lower than those in high caries group(P＜0.05). CONCLUSIONS: There are significant differences in species composition of intestinal flora but no in salivary flora between children with high caries and children without caries.

Familial clustering of dysbiotic oral and fecal microbiomes in juvenile dermatomyositis.

Juvenile dermatomyositis (JDM) is a rare immune-mediated disease of childhood with putative links to microbial exposures. In this multi-center, prospective, observational cohort study, we evaluated whether JDM is associated with discrete oral and gut microbiome signatures. We generated 16S rRNA sequencing data from fecal, saliva, supragingival, and subgingival plaque samples from JDM probands (n = 28). To control for genetic and environmental determinants of microbiome community structure, we also profiled microbiomes of unaffected family members (n = 27 siblings, n = 26 mothers, and n = 17 fathers). Sample type (oral-vs-fecal) and nuclear family unit were the predominant variables explaining variance in microbiome diversity, more so than having a diagnosis of JDM. The oral and gut microbiomes of JDM probands were more similar to their own unaffected siblings than they were to the microbiomes of other JDM probands. In a sibling-paired within-family analysis, several potentially immunomodulatory bacterial taxa were differentially abundant in the microbiomes of JDM probands compared to their unaffected siblings, including Faecalibacterium (gut) and Streptococcus (oral cavity). While microbiome features of JDM are often shared by unaffected family members, the loss or gain of specific fecal and oral bacteria may play a role in disease pathogenesis or be secondary to immune dysfunction in susceptible individuals.

The oral microbiome is associated with HPA axis response to a psychosocial stressor.

Intense psychosocial stress during early life has a detrimental effect on health-disease balance in later life. Simultaneously, despite its sensitivity to stress, the developing microbiome contributes to long-term health. Following stress exposure, HPA-axis activation regulates the "fight or flight" response with the release of glucose and cortisol. Here, we investigated the interaction between the oral microbiome and the stress response. We used a cohort of 115 adults, mean age 24, who either experienced institutionalisation and adoption (n = 40) or were non-adopted controls (n = 75). Glucose and cortisol measurements were taken from participants following an extended socially evaluated cold pressor test (seCPT) at multiple time points. The cohort´s oral microbiome was profiled via 16S-V4 sequencing on microbial DNA from saliva and buccal samples. Using mixed-effect linear regressions, we identified 12 genera that exhibited an interaction with host's cortisol-glucose response to stress, strongly influencing intensity and clearance of cortisol and glucose following stress exposure. Particularly, the identified taxa influenced the glucose and cortisol release profiles and kinetics following seCPT exposure. In conclusion, our study provided evidence for the oral microbiome modifying the effect of stress on the HPA-axis and human metabolism, as shown in glucose-cortisol time series data.

Assessment of salivary microbiota profile as a potential diagnostic tool for pediatric celiac disease.

The association between oral dysbiosis and celiac disease (CD) remains poorly understood, as does the impact of CD-associated dysbiosis on disease development or exacerbation. This study aims to investigate alterations in salivary microbial composition among children with CD. In this cross-sectional study, saliva samples from 12 children with active CD (A-CD group), 14 children with CD on a gluten-free diet (GFD), and 10 healthy control (HC) children were analyzed using DNA sequencing targeting the 16S ribosomal RNA. Both patients in A-CD and GFD groups showed a significant increase (p = 0.0001) in the Bacteroidetes phylum, while the Actinobacteria phylum showed a significant decrease (p = 0.0001). Notably, the Rothia genus and R.aeria also demonstrated a significant decrease (p = 0.0001) within the both CD groups as compare to HC. Additionally, the control group displayed a significant increase (p = 0.006) in R.mucilaginosa species compared to both CD patient groups. Distinct bacterial strains were abundant in the saliva of patients with active CD, indicating a unique composition of the salivary microbiome in individuals with CD. These findings suggest that our approach to assessing salivary microbiota changes may contribute to developing noninvasive methods for diagnosing and treating CD.

Colloidal chitosan-silver nanoparticles-fluoride nanocomposite as an antibacterial mouthwash against salivary Streptococcus mutans in orthodontic patients (a randomized clinical trial).

OBJECTIVES: This study aimed to synthesize and characterize colloidal chitosan-silver nanoparticles-fluoride nanocomposite (CCAgNPF) and evaluate its efficacy compared to chlorhexidine on salivary Streptococcus mutans in orthodontic patients. MATERIALS AND METHODS: AgNPs stabilized with chitosan were synthesized by chemical reduction of AgNO3. The nanoparticles were characterized with SEM, FTIR, DLS and ICP-OES. The MIC and MBC against S. mutans and IC50 concentration of CCAgNPF were obtained for antibacterial and cytotoxicity evaluations, respectively. For the clinical study, a total of 45 orthodontic patients were divided into three groups of 15 and used the following mouthwashes twice a day for 1 month: CCAgNPF, chlorhexidine 0.2% and the combination of these mouthwashes. The colony count of salivary S. mutans was evaluated before and after using the mouthwashes. The data were analyzed using One-way ANOVA and Tukey's test. RESULTS: Stabilized AgNPs were spherical with a diameter of 25.3 ± 3.3 nm. The MIC, MBC and IC50 of CCAgNPF were 4.42, 8.85 and 18.89 µg/ml. All mouthwashes reduced the salivary S. mutans of the orthodontic patients, however, no significant difference was found between the efficacy of CCAgNPF and chlorhexidine (P-value > 0.05). The best results were achieved by the combination of CCAgNPF and chlorhexidine mouthwashes (P-value < 0.05). CONCLUSION: The CCAgNPF and its combination with chlorhexidine present potent bactericidal, biocompatible and effective anti-carious mouthwashes for orthodontic patients. CLINICAL RELEVANCE: This study proved CCAgNPF as an antibacterial mouthwash with lower cytotoxicity and side effects for patients undergoing orthodontic treatments to maintain oral hygiene and reduce salivary S. mutans.

Effect of Using Mouthwash Containing Cibotium barometz J. Smith on Cariogenic Bacteria and Acid-producing Ability of Saliva: A Randomised Blinded Clinical Trial.

PURPOSE: To examine the anti-caries effect of mouthwashes containing Cibotium barometz J. Smith (CB), a natural substance, and compare it with chlorhexidine and saline solution. MATERIALS AND METHODS: A randomised, blinded clinical trial was conducted on 76 study participants. The differences between the 3 gargle groups (saline gargle: SAL; chlorhexidine gargle: CHX; CB gargle group: CB) and the differences over time (baseline, after 1 week, after 2 weeks) were compared. To this end, ANOVA was performed on caries-related clinical indicators (e.g. O'Leary plaque index, caries activity, and satisfaction). RESULTS: The O'Leary index, caries activity, and saliva tests, gradually improved in group CB at one and two weeks. In the case of bacterial tests, unlike SAL and CHX, only in group CB did the decrease occur one and two weeks later. The caries-related indicators decreased significantly over time in group CB compared to SAL and CHX groups, and there was also a statistically significant difference in interaction between groups and time (p<0.05). CONCLUSIONS: The mouthwash containing CB extract showed statistically significant improvement in biofilm adhesion as well as the saliva and bacterial tests compared to SAL and CHX. However, since there were differences in the initial oral conditions of the three groups, additional long-term research is needed through crossover clinical trials to supplement these.

Pilot study assessing gut microbial diversity among sexual and gender minority young adults.

Evidence supports that people identifying as a sexual or gender minority (SGMs) experience minority-related stress resulting from discrimination or expectations of prejudice, and that this is associated with increased mental and physical health problems compared to cisgender heterosexuals. However, the biological mechanisms driving minority-related stress impacts remain unknown, including the role of the gut microbiome. Thus, the aim of this study was to determine the relationship between SGM status and gut microbiome health among young adults attending a 4-year university. To this end, a prospective pilot study was completed in the fall and spring semesters of 2021-22. Self-identified SGMs (N = 22) and cisgender-heterosexuals (CIS-HET, N = 43) completed in-person interviews to provide mental health data and demographic information. Nail and saliva samples were collected at the time of interview to quantify chronic and acute cortisol. Stool samples were collected within 48 hours of interview for microbiome analysis. Assessment of the gut microbiota identified a significant reduction in alpha diversity among the SGM group, even when adjusting for mental health outcome. SGM group showed trends for higher abundance of microbes in phylum Bacteroidetes and lower abundance of microbes in phyla Firmicutes, Actinobacteria, and Proteobacteria compared to the CIS-HET group. These findings support that the gut microbiome could be contributing to negative health effects among the SGM community.

Prediction of delayed graft function by early salivary microbiota following kidney transplantation.

Delayed graft function (DGF) is a frequently observed complication following kidney transplantation (KT). Our prior research revealed dynamic shifts in salivary microbiota post-KT with immediate graft function (IGF), yet its behavior during DGF remains unexplored. Five recipients with DGF and 35 recipients with IGF were enrolled. Saliva samples were collected during the perioperative period, and 16S rRNA gene sequencing was performed. The salivary microbiota of IGFs changed significantly and gradually stabilized with the recovery of renal function. The salivary microbiota composition of DGFs was significantly different from that of IGFs, although the trend of variation appeared to be similar to that of IGFs. Salivary microbiota that differed significantly between patients with DGF and IGF at 1 day after transplantation were able to accurately distinguish the two groups in the randomForest algorithm (accuracy = 0.8333, sensitivity = 0.7778, specificity = 1, and area under curve = 0.85), with Selenomonas playing an important role. Bacteroidales (Spearman's r = - 0.4872 and p = 0.0293) and Veillonella (Spearmen's r = - 0.5474 and p = 0.0125) were significantly associated with the serum creatinine in DGF patients. Moreover, the significant differences in overall salivary microbiota structure between DGF and IGF patients disappeared upon long-term follow-up. This is the first study to investigate the dynamic changes in salivary microbiota in DGFs. Our findings suggested that salivary microbiota was able to predict DGF in the early stages after kidney transplantation, which might help the perioperative clinical management and early-stage intervention of kidney transplant recipients. KEY POINTS: • Salivary microbiota on the first day after KT could predict DGF. • Alterations in salivary taxa after KT are related to recovery of renal function.

Caries assessment and salivary microbial analysis in patients diagnosed with mucopolysaccharidosis.

BACKGROUND AND OBJECTIVES: Mucopolysaccharidosis (MPS) is a group of lysosomal storage disorders that cause the deposition of polysaccharides in cells. This causes systemic and oral manifestations, which can be observed clinically and radiographically. The present study aimed to assess dental caries, the effect of salivary pH, and the change of microflora on teeth in patients diagnosed with MPS. MATERIALS AND METHODS: The study included children affected with mucopolysaccharidosis (n = 50) and healthy children (n = 50) in the control group between 3 and 15 years of age. The pH of saliva and decayed, missing, and filled teeth/decayed extracted and filled teeth index were noted and recorded. For the microbial analysis, saliva was inoculated into blood agar, MacConkey agar, Candida CHROMagar, and Mitis Salivarius agar, then inspected for colony-forming units, which were counted and recorded based on the colony characteristics and gram staining. STATISTICAL ANALYSIS: Intergroup comparison of the test parameters was done using the Mann-Whitney test. P < 0.05 was considered statistically significant. RESULTS: The results showed significantly higher total microbial load (P = 0.00008), streptococcus viridans species (P = 0.00001), and Candida species (P = 0.0038) in the study group. The caries incidence was also higher in the study group for both primary (P = 0.0096) and permanent dentition (P = 0.0251), and salivary pH was more acidic (P = 0.00001) in the patients diagnosed with MPS. INTERPRETATION AND CONCLUSION: Patients diagnosed with MPS have a higher microbial load, more acidic saliva, and subsequently, a higher caries incidence than normal healthy children. Hence, regular dental evaluation, prevention, and treatment must be integrated into their health-care regimen.

Topical prebiotic nitrate: optimizing the 'hang-time', source and dose for specific oral or systemic effects.

In our opinion, the 'hang-time' of nitrate-containing products discussed in the letter by Green and Green is an interesting variable that should be considered when nitrate-based treatment or prevention strategies are designed. However, due to direct nitrate recycling after nitrate intake, products with a long 'hang-time' (e.g., chewing gum) may not always have an advantage compared to products with a short 'hang-time' (e.g., vegetable juices). We argue that extending the 'hang-time' is especially relevant and potentially beneficial for different applications, such as using a low nitrate dose to stimulate the oral effects, reaching oral tissues that may otherwise not be exposed to dietary nitrate (e.g., periodontal pockets), and providing a longer nitrate exposure in individuals with an impaired salivary flow. Apart from the 'hang-time', other important variables are the nitrate dose and source (e.g., different salts and vegetable extracts), as well as the desired effect (e.g., an oral effect versus systemic effects). Finally, we believe that the alterations in salivary microbiota observed before and after chewing three nitrate-rich gums over a period of ~5 h, as reported by Green and Green, could be considered beneficial. However, the oral microbiota composition is affected by the circadian rhythm and the effect of gum mastication should be evaluated. These results should thus be confirmed by a placebo-controlled study, where these confounding factors can be accounted for.

Clinical features and risk factors for Sjogren's syndrome patients suffering from oral candidiasis in Shanxi, China.

OBJECTIVES: To investigate the clinical features and risk factors of Sjogren's Syndrome (SS) patients suffering from oral candidiasis and to provide a foundation for the prevention and treatment of oral candidiasis in SS patients. METHODS: The medical records of 479 SS patients admitted to the Second Hospital of Shanxi Medical University from 2018 to 2020 were analysed to determine the clinical characteristics and risk factors that influence the occurrence of oral candidiasis infection in SS patients. RESULTS: Patients with oral candidiasis were older than those without oral candidiasis (P < 0.05). Male SS patients had greater oral candidiasis rates (P < 0.05). Unstimulated whole saliva (UWS) and stimulated whole saliva (SWS) were both shown to be adversely associated with oral Candida infections (P < 0.001). Logistic regression revealed that a low UWS was an independent risk factor for oral Candida infections in SS patients (OR: 0.004, P = 0.023). Greater WBC counts (OR: 1.22, P < 0.001), lower haemoglobin levels (OR: 0.97, P = 0.007), lower serum albumin levels (OR: 0.88, P < 0.001), lower IgG levels (OR: 0.91, P = 0.011), lower IgA levels (OR: 0.75, P = 0.011), and lower IgM levels (OR: 0.91, P = 0.015) were found in patients with oral Candida infections. Patients on immunosuppressive medications (OR: 0.32, P = 0.011), particularly rapamycin (P < 0.001), had a decreased rate of oral Candida infections. CONCLUSIONS: Patients with oral candidiasis were older than those without oral candidiasis. Male SS patients are more likely to have oral candidiasis. Individuals with lower UWS and SWS are more susceptible to oral Candida infection. Oral Candida infections in SS patients depend on their immunological status. Rapamycin may increase the abundance of Treg cells to reduce oral Candida infection in SS patients.

Manganese uptake by MtsABC contributes to the pathogenesis of human pathogen group A streptococcus by resisting host nutritional immune defenses.

The interplay between host nutritional immune mechanisms and bacterial nutrient uptake systems has a major impact on the disease outcome. The host immune factor calprotectin (CP) limits the availability of essential transition metals, such as manganese (Mn) and zinc (Zn), to control the growth of invading pathogens. We previously demonstrated that the competition between CP and the human pathogen group A streptococcus (GAS) for Zn impacts GAS pathogenesis. However, the contribution of Mn sequestration by CP in GAS infection control and the role of GAS Mn acquisition systems in overcoming host-imposed Mn limitation remain unknown. Using a combination of in vitro and in vivo studies, we show that GAS-encoded mtsABC is a Mn uptake system that aids bacterial evasion of CP-imposed Mn scarcity and promotes GAS virulence. Mn deficiency caused by either the inactivation of mtsC or CP also impaired the protective function of GAS-encoded Mn-dependent superoxide dismutase. Our ex vivo studies using human saliva show that saliva is a Mn-scant body fluid, and Mn acquisition by MtsABC is critical for GAS survival in human saliva. Finally, animal infection studies using wild-type (WT) and CP-/- mice showed that MtsABC is critical for GAS virulence in WT mice but dispensable in mice lacking CP, indicating the direct interplay between MtsABC and CP in vivo. Together, our studies elucidate the role of the Mn import system in GAS evasion of host-imposed metal sequestration and underscore the translational potential of MtsABC as a therapeutic or prophylactic target.

Increasing correlation between oral and gastric microbiota during gastric carcinogenesis.

BACKGROUND/AIMS: Recent research has increasingly focused on the role of the gastric microbiome in the development of gastric cancer. We aimed to investigate the changes in the microbiome during gastric carcinogenesis in structural and functional aspects, with a specific focus on the association between oral and gastric microbiomes. METHODS: We collected saliva, gastric juice, and gastric tissue samples from 141 patients at different stages of gastric carcinogenesis and processed them for microbiome analysis using 16S rRNA gene profiling. The alpha and beta diversities were analyzed, and the differences in microbiome composition and function profiles were analyzed among the groups, as well as the correlation between changes in the oral and gastric microbiomes during carcinogenesis. RESULTS: We observed significant differences in microbial diversity and composition between the disease and control groups, primarily in the gastric juice. Specific bacterial strains, including Schaalia odontolytica, Streptococcus cristatus, and Peptostreptococcus stomatis, showed a significant increase in abundance in the gastric juice in the low-grade dysplasia and gastric cancer groups. Notably, the correlation between the oral and gastric microbiota compositions, increased as the disease progressed. Predictive analysis of the metagenomic functional profiles revealed changes in functional pathways that may be associated with carcinogenesis (ABC transport and two-component systems). CONCLUSION: During gastric carcinogenesis, the abundance of oral commensals associated with cancer increased in the stomach. The similarity in microbial composition between the stomach and oral cavity also increased, implying a potential role of oral-gastric bacterial interactions in gastric cancer development.

Aedes albopictus saliva contains a richer microbial community than the midgut.

BACKGROUND: Past findings demonstrate that arthropods can egest midgut microbiota into the host skin leading to dual colonization of the vertebrate host with pathogens and saliva microbiome. A knowledge gap exists on how the saliva microbiome interacts with the pathogen in the saliva. To fill this gap, we need to first define the microbial composition of mosquito saliva. METHODS: The current study aimed at analyzing and comparing the microbial profile of Aedes albopictus saliva and midgut as well as assessing the impact of Zika virus (ZIKV) infection on the midgut and saliva microbial composition. Colony-reared Ae. albopictus strains were either exposed to ZIKV infectious or noninfectious bloodmeal. At 14 ays postinfection, the 16S V3-V4 hypervariable rRNA region was amplified from midgut and saliva samples and sequenced on an Illumina MiSeq platform. The relative abundance and diversity of midgut and saliva microbial taxa were assessed. RESULTS: We observed a richer microbial community in the saliva compared with the midgut, yet some of the microbial taxa were common in the midgut and saliva. ZIKV infection did not impact the microbial diversity of midgut or saliva. Further, we identified Elizabethkingia spp. in the Ae. albopictus saliva. CONCLUSIONS: This study provides insights into the microbial community of the Ae. albopictus saliva as well as the influence of ZIKV infection on the microbial composition of its midgut and saliva. The identification of Elizabethkingia spp., an emerging pathogen of global health significance, in Ae. albopictus saliva is of medical importance. Future studies to assess the interactions between Ae. albopictus saliva microbiome and ZIKV could lead to novel strategies for developing transmission barrier tools.

Comparison of biofilm models for producing artificial active white spot lesions.

OBJECTIVE: This study compared three protocols for developing artificial white spot lesions (WSL) using biofilm models. METHODOLOGY: In total, 45 human enamel specimens were sterilized and allocated into three groups based on the biofilm model: Streptococcus sobrinus and Lactobacillus casei (Ss+Lc), Streptococcus sobrinus (Ss), or Streptococcus mutans (Sm). Specimens were incubated in filter-sterilized human saliva to form the acquired pellicle and then subjected to the biofilm challenge consisting of three days of incubation with bacteria (for demineralization) and one day of remineralization, which was performed once for Ss+Lc (four days total), four times for Ss (16 days total), and three times for Sm (12 days total). After WSL creation, the lesion fluorescence, depth, and chemical composition were assessed using Quantitative Light-induced Fluorescence (QLF), Polarized Light Microscopy (PLM), and Raman Spectroscopy, respectively. Statistical analysis consisted of two-way ANOVA followed by Tukey's post hoc test (α=0.05). WSL created using the Ss+Lc protocol presented statistically significant higher fluorescence loss (ΔF) and integrated fluorescence (ΔQ) in comparison to the other two protocols (p<0.001). RESULTS: In addition, Ss+Lc resulted in significantly deeper WSL (137.5 µm), followed by Ss (84.1 µm) and Sm (54.9 µm) (p<0.001). While high mineral content was observed in sound enamel surrounding the WSL, lesions created with the Ss+Lc protocol showed the highest demineralization level and changes in the mineral content among the three protocols. CONCLUSION: The biofilm model using S. sobrinus and L. casei for four days was the most appropriate and simplified protocol for developing artificial active WSL with lower fluorescence, higher demineralization, and greater depth.

In vitro effect of TiF4/NaF solution on the development of radiation-induced dentin caries.

OBJECTIVE: To evaluate the protective effect of an experimental solution containing TiF4/NaF on the development of radiation-induced dentin caries lesions. METHODOLOGY: bovine root samples were irradiated (70Gy) and distributed as following (n=12/group): Commercial Saliva (BioXtra), NaF (500 ppm F-), TiF4 (500 ppm F), TiF4/NaF (TiF4: 300 ppm F-, NaF: 190 ppm F-), and Phosphate buffer solution (PBS, negative control). Biofilm was produced using biofilm from irradiated patients and McBain saliva (0.2% of sucrose, at 37oC and 5% CO2) for five days. The treatments were applied 1x/day. Colony-forming units (CFU) were counted and demineralization was quantified by transversal microradiography. The ANOVA/Tukey test was applied for all parameters. RESULTS: All treatments reduced CFU for total microorganisms. TiF4 reduced Lactobacillus sp. (7.04±0.26 log10 CFU/mL) and mutans streptococci (7.18±0.28) CFU the most, when compared to PBS (7.58±0.21 and 7.75±0.17) and followed by NaF (7.12±0.31 and 7.34±0.22) and TiF4/NaF (7.16±0.35 and 7.29± 0.29). TiF4 and Commercial saliva showed the lowest integrated mineral loss (ΔZ-vol%.mm) (1977±150 and 2062±243, respectively) when compared to PBS (4540±335), followed by NaF (2403±235) and TiF4/NaF (2340±200). Commercial saliva was the only to significantly reduce mineral loss (LD-µm) (111±25) compared to PBS (153±24).Mean mineral loss (R-vol%) decreased by 35.2% for TiF4 (18.2±3.3) when compared to PBS (28.1±2.9) Conclusion: TiF4/NaF has a comparable anti-cariogenic effect to TiF4 and Commercial saliva under the model in this study.

Altered salivary microbiota associated with high-sugar beverage consumption.

The human oral microbiome may alter oral and systemic disease risk. Consuming high sugar content beverages (HSB) can lead to caries development by altering the microbial composition in dental plaque, but little is known regarding HSB-specific oral microbial alterations. Therefore, we conducted a large, population-based study to examine associations of HSB intake with oral microbiome diversity and composition. Using mouthwash samples of 989 individuals in two nationwide U.S. cohorts, bacterial 16S rRNA genes were amplified, sequenced, and assigned to bacterial taxa. HSB intake was quantified from food frequency questionnaires as low (< 1 serving/week), medium (1-3 servings/week), or high (> 3 servings/week). We assessed overall bacterial diversity and presence of specific taxa with respect to HSB intake in each cohort separately and combined in a meta-analysis. Consistently in the two cohorts, we found lower species richness in high HSB consumers (> 3 cans/week) (p = 0.027), and that overall bacterial community profiles differed from those of non-consumers (PERMANOVA p = 0.040). Specifically, presence of a network of commensal bacteria (Lachnospiraceae, Peptostreptococcaceae, and Alloprevotella rava) was less common in high compared to non-consumers, as were other species including Campylobacter showae, Prevotella oulorum, and Mycoplasma faucium. Presence of acidogenic bacteria Bifodobacteriaceae and Lactobacillus rhamnosus was more common in high consumers. Abundance of Fusobacteriales and its genus Leptotrichia, Lachnoanaerobaculum sp., and Campylobacter were lower with higher HSB consumption, and their abundances were correlated. No significant interaction was found for these associations with diabetic status or with microbial markers for caries (S. mutans) and periodontitis (P. gingivalis). Our results suggest that soft drink intake may alter the salivary microbiota, with consistent results across two independent cohorts. The observed perturbations of overrepresented acidogenic bacteria and underrepresented commensal bacteria in high HSB consumers may have implications for oral and systemic disease risk.

Potential role of salivary lactic acid bacteria in pathogenesis of oral lichen planus.

BACKGROUND: Emerging evidence emphasized the role of oral microbiome in oral lichen planus (OLP). To date, no dominant pathogenic bacteria have been identified consistently. It is noteworthy that a decreased abundance of Streptococcus, a member of lactic acid bacteria (LAB) in OLP patients has been commonly reported, indicating its possible effect on OLP. This study aims to investigate the composition of LAB genera in OLP patients by high-throughput sequencing, and to explore the possible relationship between them. METHODS: We collected saliva samples from patients with OLP (n = 21) and healthy controls (n = 22) and performed 16 S rRNA gene high-throughput sequencing. In addition, the abundance of LAB genera was comprehensively analyzed and compared between OLP and HC group. To verify the expression of Lactococcus lactis, real time PCR was conducted in buccal mucosa swab from another 14 patients with OLP and 10 HC. Furthermore, the correlation was conducted between clinical severity of OLP and LAB. RESULTS: OLP and HC groups showed similar community richness and diversity. The members of LAB, Lactococcus and Lactococcus lactis significantly decreased in saliva of OLP cases and negatively associated with OLP severity. In addition, Lactococcus and Lactococcus lactis showed negative relationship with Fusobacterium and Aggregatibacter, which were considered as potential pathogens of OLP. Similarly, compared with healthy controls, the amount of Lactococcus lactis in mucosa lesion of OLP patients was significantly decreased. CONCLUSIONS: A lower amount of Lactococcus at genus level, Lactococcus lactis at species level was observed in OLP cases and associated with disease severity. Further studies to verify the relationship between LAB and OLP, as well as to explore the precise mechanism is needed.

Key periodontal pathogens may mediate potential pathogenic relationships between periodontitis and crohn's disease.

BACKGROUND: Crohn's disease (CD)-associated periodontitis is common. However, the role of periodontal pathogens in the Coexistence of CD and periodontal disease remains unclear. METHODS: To investigate the potential relationship mediated by periodontal pathogens between periodontitis and CD, we collected salivary samples from healthy participants (H group, n = 12), patients with CD (Ch group, n = 10), patients with periodontitis (Ps group, n = 12), and patients with Coexistence of CD and periodontal disease (Cp group, n = 12) and analyzed them by 16 S rRNA sequencing. RESULTS: Patients with Coexistence of CD and periodontal disease had increased levels of Fusobacterium, Actinomyces, Leptotrichia, and Prevotella, which correlated with the severity of periodontitis. Conversely, the levels of Streptococcus, Neisseria, Haemophilus, and Gemella, which decreased in Coexistence of CD and periodontal disease, were negatively correlated with the severity of periodontitis. To further investigate the role of periodontal pathogens in CD development, representative periodontal pathogens causing periodontitis, Porphyromonas gingivalis and Fusobacterium nucleatum, were administered to mice. These pathogens migrate to, and colonize, the gut, accelerating CD progression and aggravating colitis, and even systemic inflammation. In vitro experiments using a Caco-2/periodontal pathogen coculture revealed that P. gingivalis and F. nucleatum increased intestinal permeability by directly disrupting the tight junctions of intestinal epithelial cells. CONCLUSION: Our findings strongly suggest that periodontal pathogens play a role in the relationship between periodontitis and CD. These results provide a basis for understanding the pathogenesis of Coexistence of CD and periodontal disease and may lead to the development of novel therapeutic strategies.

Genome-wide association study identifies host genetic variants influencing oral microbiota diversity and metabolic health.

The microbial communities of the oral cavity are important elements of oral and systemic health. With emerging evidence highlighting the heritability of oral bacterial microbiota, this study aimed to identify host genome variants that influence oral microbial traits. Using data from 16S rRNA gene amplicon sequencing, we performed genome-wide association studies with univariate and multivariate traits of the salivary microbiota from 610 unrelated adults from the Danish ADDITION-PRO cohort. We identified six single nucleotide polymorphisms (SNPs) in human genomes that showed associations with abundance of bacterial taxa at different taxonomical tiers (P < 5 × 10-8). Notably, SNP rs17793860 surpassed our study-wide significance threshold (P < 1.19 × 10-9). Additionally, rs4530093 was linked to bacterial beta diversity (P < 5 × 10-8). Out of these seven SNPs identified, six exerted effects on metabolic traits, including glycated hemoglobin A1c, triglyceride and high-density lipoprotein cholesterol levels, the risk of type 2 diabetes and stroke. Our findings highlight the impact of specific host SNPs on the composition and diversity of the oral bacterial community. Importantly, our results indicate an intricate interplay between host genetics, the oral microbiota, and metabolic health. We emphasize the need for integrative approaches considering genetic, microbial, and metabolic factors.