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:Streptococcus mutans, the primary etiologic agent of human dental caries, and a variety of oral Streptococcus and Actinomyces spp. synthesize high molecular mass homopolymers of fructose (fructans) with predominantly β2,1- (inulins) or β2,6-linkages (levans). The ability of S. mutans to degrade fructans contributes to the severity of dental caries. The extracellular product of fruA of S. mutans is an exo-β-D-fructofuranosidase that releases fructose from levan and inulin. Located 70 bp downstream of fruA, fruB encodes a member of the glycoside hydrolase family 32, but the function of FruB has not been established.In this study, the transcriptomic analysis of UA159 and a fruB mutant grown on 0.2% levan revealed differential expression of genes encoding ABC transporters, transcriptional regulators and genes involved in growth and stress tolerance. The results provide new insights into the mechanisms of action by which FruB utilizes homo-polymers of fructose, specifically levan. The findings significantly enhance our understanding of the genetics and physiology of this cariogenic pathogen S. mutans.
Project description:Recent RNA-seq studies have given us a deeper insight into the cariogenic impact of carbohydrate sources in the bacterium Streptococcus mutans, the principal etiological agent of human dental caries. The process of dental caries development is given by the ability of this bacterium to ferment some carbohydrates up to organic acids contributing to the pH decrease in the oral cavity and the demineralization of the enamel. Besides, in dental caries progression, an important role is played by biofilm formation, which starts and ends with free planktonic cells, and it is given by several unique properties called virulence factors. The most cariogenic carbohydrate is considered sucrose, an easily metabolizable source of energy inducing acidification and synthesis of glucans forming typical bacterial cell clumps. By using multifaceted methodological approaches, we compared the transcriptomic and metabolomic profiles of S. mutans growing in planktonic culture on preferred and non-preferred carbohydrates and fasting conditions. Lactose and xylitol showed high effectiveness in the regulation of the IPS metabolism, cell wall structure and overall virulence involved in the initial phase of biofilm formation and structure but with an opposite pattern compared to sucrose and glucose. These findings confirm the recent results that xylitol and lactose play a vital role in biofilm structure but do not reduce its formation related to their cariogenic potential.
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: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: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.