The role of bacterial communication in the shift from disease to health in the oral cavity

Background
The human oral cavity harbours over 900 different bacterial phylotypes. A delicately balanced symbiosis between oral microbes and host immune cells ensures a stable oral environment. Changes in this balance can lead to dysbiosis and disease, and recent data supports an intimate relationship between the oral biofilms and host response, whereby inflammation drives dysbiosis and vice versa. Physiological and environmental factors are important in the regulation of oral health and in the development of the dental plaque. Microorganisms within the oral biofilm (plaque) co-aggregate and interact with each other in an organised fashion. Bacteria communicate within their own species, but also across species and with eukaryotic cells. However, this communication and its role in virulence factor expression and biofilm maturation in the oral cavity is poorly understood. Quorum sensing (QS), a form of bacterial cell-cell communication, dependent on cell density, requires further investigation. It was shown elsewhere that interruption of quorum sensing circuits can be used to reduce pathogenicity and aid future treatment and prevention strategies.

Hypothesis
QS contributes to the establishment and maintenance of a disease-associated plaque biofilm.
Objectives/Methods
Part 1: Genomics
- Analysis of genomes of defined Periodontal pathogens in search of QS genes, cyclic di AMP and GMP
Part 2: Molecular Microbiology
- Characterise mutants (pathogenicity, biofilm formation, co-aggregation, interaction with eukaryotic cells)
- Determine QS molecules
Part 3: Models
- Models of plaque: mono to multi-species biofilms
- Cell-bacterial models
Part 4: Application
- Detection of QS molecules in plaque, GCF or Saliva in health and disease
- QS blockers to reduce biofilms
Expected Outcomes
- Novel detection methods of Periodontal risk and disease status
- New models to study bacterial and host interactions, in particular communication.