Role of Muramyl Dipeptide in Lipopolysaccharide-Mediated Biological Activity and Osteoclast Activity

Figure 2

Schematic of the role of MDP in LPS-induced osteoclast formation. LPS induces TNF-α expression; MDP further enhances this TNF-α expression. MDP-enhanced, LPS-induced TNF-α may lead to an increase in RANKL expression by stromal cells. Furthermore, LPS also acts to induce RANKL expression; MDP further enhances this RANKL expression in stromal cells. The MDP-enhanced, LPS-induced TNF-α production synergistically interacts with MDP-enhanced, LPS-induced RANKL, thereby leading to increased induction of osteoclastogenesis. Therefore, the role of MDP in LPS-induced osteoclast formation in vivo may be to strongly promote the induction of this process.