The CrossTalk Group: Studies on the communication among bacteria and host cells in the oral cavity
A reciprocal beneficial relationship has developed between the host and its symbionts through evolution. In return for providing a stable, energy- and nutrient-rich environment for the resident flora, the host receives essential nutrients as well as essential signals needed for the development and normal function of several organs, including the immune system. Mutual beneficial associations secure homeostasis, made possible through communication between prokaryotes and eukaryotes via diverse small signal molecules and cell-cell contact.
Streptococcus mutans in a biofilm. Photo: Steinar Stølen, IOB.
In the human oral cavity, the microbiota is mostly organized as biofilms on teeth and mucosal surfaces. Biofilms are complex communities of bacteria enclosed in a self-produced matrix of polysaccharides, proteins and DNA. Biofilm formation, composition and activity are regulated by intra- and inter-bacterial communication. The biofilm matrix protects bacteria from the host immune system as well as from antimicrobial compounds, rendering them 10-1000 times less susceptible.
The overall aim of the projects within the CrossTalk Group is to study communication between bacteria and between bacteria and the host cells in the oral cavity, in order to understand commensal versus pathogen colonization, with the goal to promote homeostasis. Specifically; how are oral biofilms formed, how can their formation be affected, what is their role in the development of resistance to antibiotics, and how do commensals avoid eradication from the oral cavity.
Microbes that grow in the biofilm, are particularly difficult to eliminate because the biofilm protects them against the immune system and chemicals. This "resistance" involves multiple mechanisms that include various characteristics associated with changes in gene expression.
The differentiated gene expression taking place in biofilms is often controlled by bacterial signaling molecules. Our research area focuses on the understanding of such signal functions. We study how they affect the bacteria's ability to form biofilms and to express virulence. Another important area is to develop strategies to influence biofilm formation via signal interference.