Does Xylitol Tolerant S. mutans have Altered Susceptibility to B-defensins?

Principal Investigator: Marilyn Roberts

The goal of this pilot study is to examine the antibacterial activity of ß-defensins against xyiltol susceptible (isolated at baseline and thought to be more pathogenic) and xylitol tolerant (isolated after xylitol exposure and thought to be less pathogenic) strains of S. mutans. The isolates currently available are from children, adults and laboratory created. Additional pairs of S. mutans will be collected from Native Alaskans during the Disparity Center study.

The antibacterial activity of each peptide will be examined alone (hBD- 1 and hBD-2) and in combination with each other (hBD-1 plus hBD-2) using an established assay. We anticipate that the ß-defensins may be less effective against the xylitol tolerant S. mutans. This would be a novel finding and help in our understanding of why xylitol exposure reduces the risk of caries without necessarily reducing the absolute number of S. mutans or reducing the percentage of the flora that is S. mutans after xylitol use.

This study will directly benefit the Disparity Center’s two clinical studies, which will be using xylitol for caries prevention. In addition, this will open a new area of research for Dr. Roberts' laboratory and will complement the current work on carriage of antibiotic and/or heavy metal resistance in oral bacteria and lead to a variety of new funding opportunities.

In this project this single nucleotide polymorphism (SNP) found in hTLR genes will be examined for its association with periodontitis in 100 Hispanic military subjects (50 with disease and 50 age-matched controls). Our overall hypothesis is that: TLR pleomorphisms can account for differing susceptibilities to or severity of periodontitis observed among different human minority populations.

This information will aid health workers in identifying those individuals of a minority population at risk for developing periodontitis and will contribute to better health care by providing new information concerning the molecular basis of increased susceptibility to and severity of disease.