In natural environment, bacteria form communities, biofilms, on surfaces. In biofilms, bacteria are more resistant than their planktonic forms to antimicrobials and host defense factors. Reasons for biofilm resistance to external forces include a protective extracellular matrix and formation of non-dividing persister cells. In humans, bacterial biofilms cause chronic infections. One of common biofilm diseases in humans is periodontitis, a persistent multispecies infection triggering chronic inflammation in tooth-supporting tissues. Periodontitis is characterized by active and less active phases in inflammation and tissue destruction suggesting that there might be certain type of pathogen-host crosstalk. It has been suggested that bacteria growing in biofilms could exploit proinflammatory cytokines produced by the host. Thus cytokine network aimed to enhance the clearance of pathogens might actually promote bacterial survival in protective biofilm.
Our research is focused on studying biofilm-host interaction in chronic infection, periodontitis. We use Aggregatibacter actinomycetemcomitans (Aa), a major pathogen in aggressive periodontitis, as model bacterium. In particular we are interested how the outer membrane proteins are involved in sensing the host response in inflammation. The research include molecular- and structural biology methods, flow cytometry and electron- and atomic force microscopy. In addition, we study the biofilm-host interaction by using cell culture model which mimics the dento-gingival junction.