Project description:Within the mouth bacteria are starved of saccharides as their main nutrient source between meals and it is unclear what drives their metabolism. Previously oral in vitro biofilms grown in saliva have shown proteolytic degradation of salivary proteins and increased extracellular proline. Although arginine and glucose have been shown before to have an effect on oral biofilm growth and activity, there is limited evidence for proline. Nuclear magnetic resonance (NMR) spectroscopy was used to identify extracellular metabolites produced by bacteria in oral biofilms grown on hydroxyapatite discs. Biofilms were inoculated with whole mouth saliva and then grown for 7 days using sterilised whole mouth saliva supplemented with proline, arginine and glucose as a growth-medium. Overall proline had a beneficial effect on biofilm growth – with significantly fewer dead bacteria present by biomass and surface area of the biofilms (p <0.05). Where arginine and glucose significantly increased and decreased pH, respectively, the pH of proline supplemented biofilms remained neutral at pH 7.3-7.5. SDS-polyacrylamide gel electrophoresis of the spent saliva from proline and arginine supplemented biofilms showed inhibition of salivary protein degradation of immature biofilms. NMR analysis of the spent saliva revealed that proline supplemented biofilms were metabolically similar to unsupplemented biofilms, but these biofilms actively metabolised proline to 5-aminopentanoate, butyrate and propionate, and actively utilised glycine. This study shows that in a nutrient limited environment, proline has a beneficial effect on in vitro oral biofilms grown from a saliva inoculum.
Project description:Natural compounds that can stimulate salivary secretion are of interest in developing treatments for xerostomia, the perception of a dry mouth, that affects between 10 and 30% of the adult and elderly population. Chemesthetic transient receptor potential (TRP) channels are expressed in the surface of the oral mucosa. The TRPV1 agonists capsaicin and piperine have been shown to increase salivary flow when introduced into the oral cavity but the sialogogic properties of other TRP channel agonists have not been investigated. In this study we have determined the influence of different TRP channel agonists on the flow and protein composition of saliva. Mouth rinsing with the TRPV1 agonist nonivamide or menthol, a TRPM8 agonist, increased whole mouth saliva (WMS) flow and total protein secretion compared to unstimulated saliva, the vehicle control mouth rinse or cinnamaldehyde, a TRPA1 agonist. Nonivamide also increased the flow of labial minor gland saliva but parotid saliva flow rate was not increased. The influence of TRP channel agonists on the composition and function of the salivary proteome was investigated using a multi-batch quantitative mass spectrometry method novel to salivary proteomics. Inter-personal and inter-mouth rinse variation was observed in the secreted proteomes and, using a novel bioinformatics method, inter-day variation was identified with some of the mouth rinses. Significant changes in specific salivary proteins were identified after all mouth rinses. In the case of nonivamide, these changes were attributed to functional shifts in the WMS secreted, primarily the over representation of salivary and non-salivary cystatins which was confirmed by immunoassay. This study provides new evidence of the impact of TRP channel agonists on the salivary proteome and the stimulation of salivary secretion by a TRPM8 channel agonist, which suggests that TRP channel agonists are potential candidates for developing treatments for sufferers of xerostomia
Project description:Background: Hypertension is one of the most common metabolic diseases in the elderly and its pathogenesis is associated with microbiota dysbiosis. Recent evidence suggests that oral microbiota dysbiosis is also an important factor in the development of hypertension. However, the relationship between hypertension and oral flora in the elderly has not been adequately investigated. Objective: The aim of this cross-sectional study was to investigate the structure of the oral microbiota and its correlation with hypertension in elderly hypertensive patients. To provide new ideas for the prevention and treatment of hypertension. Methods: 206 subjects aged 60 ~ 89 years were selected and divided into normal (CON) and hypertensive (HTN) groups, according to the 2018 Chinese Guidelines for the Management of Hypertension. The oral microbiome composition of saliva samples was determined by 16S rRNA gene sequencing. Results: Although there was no significant difference in α and β diversity between the two groups, systolic and diastolic blood pressure were the most important factors influencing the structure of the oral microbiota. At the phylum level, the relative abundance of the spirochete phylum and the mutualistic bacterial phylum was higher in the HT group than in the CON group (p < 0.05). Diastolic blood pressure was negatively correlated with Streptococcus. Furthermore, we analyzed HTN patients with 120 mmHg<systolic blood pressure<160 mmHg and systolic blood pressure>160 mmHg separately and found that the abundance of Saccharibacteria_(TM7) was significantly increased in the HTN_2 group. Conclusions: Our study identified specific oral microbiota in elderly hypertensive patients, confirming the relationship between oral microbiota and hypertension. This enhances our understanding of the important role of oral microbiota in the pathogenesis of hypertension and accumulates more evidence for microbial involvement in the development of hypertension.
Project description:Our group recently transcriptomically characterized coculture growth between Streptococcus mutans and several species of commensal streptococci (Rose et al, 2023). However, these experiments were carried out in our lab-based experimental medium, tryptone and yeast extract (TY-). To understand whether culturing these species within a medium that more closely mimics their natural environment alters the interaction, we evaluated both monoculture and coculture growth between the dental caries pathogen Streptococcus mutans and oral commensal species Streptococcus oralis in a half TY- / half human saliva mix that was optimally chosen based on our initial characterization of oral streptococci behaviors in medium mixes containing saliva. Our results surprising show that inclusion of saliva enhances the competition of Streptococcus mutans against commensal streptococci through upregulation of carbohydrate uptake and glycolytic pathways.