The inhibitory effect of alendronate and taurine on osteoclast differentiation mediated by Porphyromonas gingivalis sonicates in vitro

The objective of this study was to investigate the ability of alendronate and taurine in inhibiting in vitro osteoclast differentiation induced by bacteria. Whole cell sonicates of Porphyromonas gingivalis were used as an osteoclast-stimulating factor in a mouse coculture system and differentiated osteoclasts were confirmed by tartrate-resistant acid phosphatase (TRAP) staining. Alendronate at the concentrations of 10(-7) M, 10(-6) M, and 10(-5) M and taurine at the concentrations of 4 mM, 8 mM, and 12 mM were used. The cytotoxic effects of alendronate and taurine were examined using methylthiazole-tetrazolium bromide (MTT) assay. The amounts of interleukin-6 (IL-6) in culture supernatants were also measured using ELISA. The sonicates of P. gingivalis at the concentration of 0.01-0.1 microg/ml significantly stimulated the formation of osteoclasts (p < 0.05). Alendronate (10(-5) M) and taurine (12 mM) significantly suppressed the sonicate-stimulated osteoclast formation. In MTT assay, no cytotoxic effects were evident in all concentrations of alendronate and taurine. Alendronate and taurine did not affect the amount of IL-6 induced by P. gingivalis sonicates. These data indicate that alendronate and taurine have inhibitory effects on bacteria-stimulated osteoclast formation in vitro and that this inhibitory mechanism is not related to the blocking of IL-6 production.