SURFACE-ASSOCIATED PROTEIN FROM STAPHYLOCOCCUS-AUREUS STIMULATES OSTEOCLASTOGENESIS - POSSIBLE ROLE IN S-AUREUS-INDUCED BONE PATHOLOGY

Objective. Staphylococcus aureus is the cause of bone destruction in o steomyelitis, bacterial arthritis and orthopaedic implant failure. We have previously shown that gentle saline extraction of S. aureus has r evealed the presence of an extremely potent stimulator of osteoclast a ctivation in both the murine calvarial bone resorption assay and the i solated chick osteoclast resorption assay. In order to investigate the mechanism of action of this surface;associated material (SAM), we hav e investigated its capacity to recruit osteoclasts. Methods. The murin e bone marrow osteoclast recruitment assay was used. The ability of th e recruited cells to resorb dentine slices was also investigated. Resu lts. The SAM from S. aureus dose dependently stimulated tartrate-resis tant acid phosphatase (TRAP)-positive osteoclast formation and pit for mation on dentine slices. Neutralization of the cytokines tumour necro sis factor alpha and interleukin (IL)-6 totally inhibited, but antagon ism of IL-1 only partially blocked, the stimulated maturation of osteo clast-like cells. Conclusion. These findings suggest that bone destruc tion associated with local infection by S. aureus is due to the stimul ation of osteoclast formation induced by the action of the easily solu bilized SAM, and could explain the large numbers of osteoclasts found in infarcted bone in osteomyelitis.