Project description:Bifidobacteria, one of the relatively dominant components of the human intestinal microbiota, are considered one of the key groups of beneficial intestinal bacteria (probiotic bacteria). However, in addition to health-promoting taxa, the genus Bifidobacterium also includes Bifidobacterium dentium, an opportunistic cariogenic pathogen. The genetic basis for the ability of B. dentium to survive in the oral cavity and contribute to caries development is not understood. The genome of B. dentium Bd1, a strain isolated from dental caries, was sequenced to completion to uncover a single circular 2,636,368 base pair chromosome with 2,143 predicted open reading frames. Annotation of the genome sequence revealed multiple ways in which B. dentium has adapted to the oral environment through specialized nutrient acquisition, defences against antimicrobials, and gene products that increase fitness and competitiveness within the oral niche. B. dentium Bd1 was shown to metabolize a wide variety of carbohydrates, consistent with genome-based predictions, while colonization and persistence factors implicated in tissue adhesion, acid tolerance, and the metabolism of human saliva-derived compounds were also identified. Global transcriptome analysis demonstrated that many of the genes encoding these predicted traits are highly expressed under relevant physiological conditions. This is the first report to identify, through various genomic approaches, specific genetic adaptations of a Bifidobacterium taxon, Bifidobacterium dentium Bd1, to a lifestyle as a cariogenic microorganism in the oral cavity. In silico analysis and comparative genomic hybridization experiments clearly reveal a high level of genome conservation among various B. dentium strains. The data indicate that the genome of this opportunistic cariogen has evolved through a very limited number of horizontal gene acquisition events, highlighting the narrow boundaries that separate commensals from opportunistic pathogens.
Project description:We present a collection of single-cell transcriptomic profiles of 6,810 pulpal cells isolated from a sound human maxillary third molars and carious teeth at different stages. We showed that the presence of deep, but not enamel caries, altered the immune cell compositions of the dental pulp. Differential expression analysis further revealed that the pro-inflammatory, anti-inflammatory and mineralization-related genes were upregulated in immune and stromal cells in deep dental caries. Cell-cell interaction prediction showed potential interactions between immune and stromal cells during homeostasis, and enhanced interactions between different cell types with macrophage during deep dental caries. Taken together, our study serves as a comprehensive survey of human pulpal cell heterogeneity, as well as provides novel molecular insights into dental pulps in health and disease.
Project description:Streptococcus mutans is a common constituent of oral biofilms and a primary etiologic agent of human dental caries. The bacteria associated with dental caries have a potent ability to produce organic acids from dietary carbohydrates and to grow and metabolize in acidic conditions. In this study, we observed supplementation with 1.5% arginine (final concentration) had inhibitory effects on the growth of S. mutans in complex and chemically defined media, particularly when cells were exposed to acid or oxidative stress. Deep-sequencing of RNA (RNA-Seq) comparing the transcriptomes of S. mutans growing in a chemically defined medium with and without 1.5% arginine in neutral and acidic pH conditions and under oxidative stress conditions revealed interesting results. The results provide new insights into the mechanisms of action by which arginine inhibits dental caries through direct adverse effects on multiple virulence-related properties of the most common human dental caries pathogen. The findings significantly enhance our understanding of the genetics and physiology of this cariogenic pathogen.
Project description:β-d-fructofuranosyl glycosidases are enzymes that produce health-beneficial fructooligosaccharides from natural fructans. In a recent issue of JBC, Kashima et al. identified a novel α-d-fructofuranosyl-active enzyme, αFFase1, from the caries-associated bacterium Bifidobacterium dentium. αFFase1 reversibly forms a potential prebiotic also found in caramel, difructose dianhydride I, via intramolecular condensation of the substrate inulobiose. Kashima et al. elegantly combine NMR, X-ray crystallography, and molecular dynamics to describe an original mechanism for the reversible reactions catalyzed by αFFase1 that establishes the new glycoside hydrolase family GH172.
Project description:The study aims to assess gene expression in plaque samples collected from twin pairs that are both concordant and discordant with respect to dental Caries diagnosis. File Naming Conventions are as follows: Patient ID : 4 digit identifier Diagnosis : Caries Negative(CN) or Caries Positive(CP) Type of Twin: Monozygotic(MZ)or Dizygotic(DZ) Pair to xxxx: 4 digit twin identifier maps to the Patient ID E.g: 2126_CP_MZ_PairTo_2125_fastqc - 2126 is a caries positive patient and pairs to monozygotic twin pair 2125. Plaque samples from twin pairs that are both concordant and discordant with respect to dental Caries diagnosis are enriched for bacterial messenger RNA to study the gene expression differences in the samples. RNA was extracted from RNAprotect (Qiagen, In c.) treated dental plaque scrapings from 38 patients. Amplified cDNA was created and rRNA sequence was removed by subtractive hybridization. Individual patient samples were run on a single lane of an Illumina Genome Analyzer.
Project description:The study aims to assess gene expression in plaque samples collected from twin pairs that are both concordant and discordant with respect to dental Caries diagnosis. File Naming Conventions are as follows: Patient ID : 4 digit identifier Diagnosis : Caries Negative(CN) or Caries Positive(CP) Type of Twin: Monozygotic(MZ)or Dizygotic(DZ) Pair to xxxx: 4 digit twin identifier maps to the Patient ID E.g: 2126_CP_MZ_PairTo_2125_fastqc - 2126 is a caries positive patient and pairs to monozygotic twin pair 2125. Plaque samples from twin pairs that are both concordant and discordant with respect to dental Caries diagnosis are enriched for bacterial messenger RNA to study the gene expression differences in the samples.
Project description:The composition of the salivary microbiota has been reported to differentiate between patients with periodontitis, dental caries and orally healthy individuals. Thus, the purpose of the present investigation was to compare metaproteomic profiles of saliva in oral health and disease. Stimulated saliva samples were collected from 10 patients with periodontitis, 10 patients with dental caries and 10 orally healthy individuals. Samples were analyzed by means of shotgun proteomics. 4161 different proteins were recorded out of which 1946 and 2090 were of bacterial and human origin respectively. The human proteomic profile displayed significant overexpression of the complement system and inflammatory mediators in periodontitis and dental caries. Bacterial proteomic profiles and functional annotation were very similar in health and disease. Data revealed multiple potential salivary proteomic biomarkers of oral disease. In addition, comparable bacterial functional profiles were observed in periodontitis, dental caries and oral health, which suggest that the salivary microbiota predominantly thrives in a planktonic state expressing no characteristic disease-associated metabolic activity. Future large-scale longitudinal studies are warranted to reveal the full potential of proteomic analysis of saliva as a biomarker of oral health and disease.
Project description:Background. Hematopoietic cell transplantation (HCT) is a potentially curative therapy for a wide range of pediatric malignant and nonmalignant diseases. However, complications, including blood stream infection (BSI) remain a major cause of morbidity and mortality. While certain bacteria that are abundant in the oral microbiome, such as S. mitis, can cause BSI, the role of the oral microbial community in the etiology of BSI is not well understood. The finding that the use of xylitol wipes, which specifically targets the cariogenic bacteria S. mutans is associated with reduced BSI in pediatric patients, lead us to investigate dental caries as a risk factor for BSI. Methods. A total of 41 pediatric patients admitted for allogenic or autologous HCT, age 8 months to 25 years, were enrolled. Subjects with high dental caries risk were identified as those who had dental restorations completed within 2 months of admission for transplant, or who had untreated decay. Fisher’s exact test was used to determine if there was a significant association between caries risk and BSI. Dental plaque and saliva were collected on a cotton swab from a subset of 4 high caries risk (HCR) and 4 low caries risk (LCR) children following pretransplant conditioning. 16SrRNA sequencing was used to compare the microbiome of HCR and LCR subjects and to identify microbes that were significantly different between the 2 groups. Results. There was a statistically significant association between caries risk and BSI (p<0.035) (Fisher’s exact test). Multivariate logistic regression analysis showed children in the high dental caries risk group were 21.39 times more likely to have BSI, with no significant effect of age or mucositis severity. HCR subjects showed significantly reduced microbial alpha diversity as compared to LCR subjects. LEfse metagenomic analyses, showed the oral microbiome in HCR children enriched in order Lactobacillales. This order includes Streptococcus and Lactobacillus, both which contain bacteria primarily associated with dental caries. Discussion. These findings support the possibility that the cariogenic microbiome can enhance the risk of BSI in pediatric populations. Future metagenomic analyses to measure microbial differences at, before, and after conditioning related to caries risk, may further unravel the complex relationship between the oral microbiome, and whether it affects health outcomes such as BSI.
Project description:Human saliva microbiota is phylogenetically divergent among host individuals yet their roles in health and disease are poorly appreciated. We employed a microbial functional gene microarray, HuMiChip 1.0, to reconstruct the global functional profiles of human saliva microbiota from ten healthy and ten caries-active adults. Saliva microbiota in the pilot population featured a vast diversity of functional genes. No significant distinction in gene number or diversity indices was observed between healthy and caries-active microbiota. However, co-presence network analysis of functional genes revealed that caries-active microbiota was more divergent in non-core genes than healthy microbiota, despite both groups exhibited a similar degree of conservation at their respective core genes. Furthermore, functional gene structure of saliva microbiota could potentially distinguish caries-active patients from healthy hosts. Microbial functions such as Diaminopimelate epimerase, Prephenate dehydrogenase, Pyruvate-formate lyase and N-acetylmuramoyl-L-alanine amidase were significantly linked to caries. Therefore, saliva microbiota carried disease-associated functional signatures, which could be potentially exploited for caries diagnosis. The DMFT INDEX (Decayed, Missing, Filled [DMF] teeth index used in dental epidemiology) values are provided for each sample