LOCAL LEVELS OF INTERLEUKIN-1β, -4, -6, AND TUMOR NECROSIS FACTOR α IN AN EXPERIMENTAL MODEL OF MURINE OSTEOMYELITIS DUE TO STAPHYLOCOCCUS AUREUS

Abstract The purpose of this study is to evaluate local levels of interleukin-1β (IL-1β), -4 (IL-4), -6 (IL-6), and tumour necrosis factor-α (TNF-α), in a model of murine osteomyelitis due to Staphylococcus aureus . Cytokine levels in supernatants derived from bone homogenates were determined by enzyme-linked immunosorbent assay, for 28 days following the direct implantation of murine tibiae with S. aureus . Levels of IL-1βand IL-6 in infected bone were elevated in the early post-infection period and then decreased. In contrast, TNF-αlevels remained elevated 3 to 28 days post-infection, while IL-4 levels were elevated late in the course of infection. The histopathology of infected bone showed predominant infiltration of inflammatory cells and bone resorption 3 to 7 days after infection, and bone resorption and adjacent areas of formation 14 to 28 days after infection. These results suggest that the elevated IL-1βand IL-6 levels induced by infection may be related to bone damage mainly in the early phase of infection, and that TNF-αand IL-4 may at least in part be associated with histopathological changes, including both bone resorption and formation in the later phase of this osteomyelitis model.