Principal investigator Dr. Reindert Nijland (
R.Nijland@umcutrecht.nl)
Planktonic bacteria growing in shakeflasks and sessile bacteria in biofilms behave very differently. For instance, the gene expression and production of secreted proteins is very different between these modes of growth. We study the dynamics in Staphylococcus aureus biofilm and specifically the interaction of the biofilm with the human innate immune system.
In our group we identified multiple immune evasion molecules produced by S. aureus.
These molecules target many compounds of the innate
immune system, such as leukocyte receptors that recognize bacteria or molecules of the complement system.
To investigate the role of these immune evasion molecules in a biofilm context, we use both an adhesion-independent biofilm model and a continuous flow cell setup. Using promoter-fluorescent protein fusions we study the expression dynamics of the immune modulating proteins in S. aureus biofilms by flow cytometry and (confocal) fluorescence microscopy. Furthermore, by screening the proteins secreted by these biofilms we directly asses the production of known and novel immune modulating proteins.
Using the promoter activity of several know immune evasion molecules and know biofilm specific proteins we can selectively home in on the developmental stages in biofilms growth relevant to immune evasion. By challenging the biofilm with compounds of the immune system (serum, neutrophils, whole blood) while performing time-lapse confocal laser scanning microscopy we are able to study the interaction of the biofilm with these compounds in a direct and dynamic way.