Methods: P. gingivalis W50 strain was grown for 6 days and the culture supernatant was collected. The multipotent mesenchymal stem cell C3H10T1/2 and the stromal cell W20-17 lines were used for studies. These murine pre-osteoblastic cell lines were cultured and challenged with ascending protein concentrations of P. gingivalis culture supernatant for 6 h, 24 h and 48 h. Cell lysates and culture supernatants were collected so that total OPG levels could be evaluated by ELISA.
Results: The basal levels of OPG production were higher in 10T1/2 cells, compared to W20-17 cells. Challenge with P. gingivalis W50 strain reduced OPG production by both cell lines. This effect was time- and concentration-dependent. In 10T1/2 cells, challenge with 20 μg/ml P. gingivalis protein resulted in a reduction of OPG production by 61.4% and 71.3%, after 24 h and 48 h respectively, compared to the control. In W20-17 cells, challenge with 20 μg/ml P. gingivalis protein resulted in a reduction of OPG production by 88.8% and 93.7% after 24 h and 48 h respectively, compared to the control.
Conclusion: These results suggest that P. gingivalis down-regulates OPG production in murine osteoblasts in a time- and concentration dependent manner. This decrease may favour conditions for local stimulation of osteoclastogenesis and bone resorption.