Methods: P. gingivalis strains 381, HW24D1 and W83 cells were grown anaerobically. MIC measurement of P. gingivalis cells was performed, and planktonic cells were grown with sub-MIC AZM for 48h. P. gingivalis biofilms were formed by circulating planktonic cells for 14 days using the flow cell model and the culture mediums containing sub-MICs were perfused for 3 days. After exposure to antibiotics, protein expressions of P. gingivalis planktonic, biofilm, and biofilm-detached cells under the conditions with sub-MIC AZM were measured using SDS-PAGE. Also, for several proteins whose change were observed were performed protein analysis using LC-MS/MS. In all the experiments, controls were incubated with broth only.
Results: The MICs for P. gingivalisstrains 381, HW24D1 and W83 were 0.5, 0.3 and 0.6 µg/ml, respectively. In biofilm cells, no difference was observed between AZM and control group in all strains. In biofilm-detached and planktonic cells, different protein expression was mainly observed at about 50 and 110 kDa compared to without AZM group.
Conclusions: Altered protein expressions were observed on sub-MIC AZM treated biofilm-detached and planctonic cells compared to non-treated cells. It is suggested that sub-MIC AZM has an inhibitory effect on P. gingivalis biofilms via altering protein expressions. The present study was supported by a Grant-in-Aid for Scientific Research (# 23890103, #24390424 and #24390425) from JSPS.