Effect of fluid flow on both the invasive ability of the periodontal pathogen P.gingivalis and the host cell uptake of these bacteria.

P.gingivalis is thought to play a key role in periodontal disease and has the ability to invade host cells where it can survive and avoid host defences and therapeutic interventions. Recent work in our laboratory has shown that low levels of fluid flow (150µl/min) enhances endocytosis of eukaryotic cells and uptake of labelled dextrans (1) and thus invasion of bacteria may similarly be affected. Previous studies have shown that microenvironmental conditions such as similar levels of fluid flow can have a significant impact on P.gingivalis biofilm morphology and growth behaviour (2). Furthermore, a recent comparison between planktonic and biofilm grown P.gingivalis has identified changes in a number of genes (3) that may be important in invasion and or intracellular life as a number are common to those identified by our group in hyper-invasive strains (4). We thus hypothesise that fluid flow may enhance both the ability of bacteria to invade host cells and the susceptibility of such cells. Biofilm growth may also favour development of this invasive phenotype.

Specific objectives:
1. Determine the effect of fluid flow to the invasion of host cells by P.gingivalis.
2. Determine the effect of exposing P.gingivalis biofilms to fluid flow on the invasive ability of this organism including analysis of cells that become detached under such conditions.
3. The influence of other relevant bacterial species will also be studies using mixed biofilms.

The mechanism of interaction between host cell and P.gingivalis under flow conditions may be significantly different from those elucidated in static culture conditions and thus may reveal novel pathways to target to prevent bacterial internalisation. Such a strategy would be of interest to those developing therapeutic agents to treat periodontal disease.