Fig. 3.

Indirect effects of MSU crystal-stimulated RAW264.7 macrophage conditioned medium on MLO-Y4 cell gene expression. RAW264.7 macrophages were cultured with or without 0.5 mg/mL monosodium urate (MSU) crystals for 24 h for preparation of MSU crystal-stimulated conditioned medium and control conditioned medium, respectively. Conditioned medium preparations were added to MLO-Y4 cells (40% final concentration in a well) for 0, 1, 6, and 24 h. MLO-Y4 cells were harvested and real-time PCR was used to determine changes in the relative mRNA expression levels of a bone-related and b inflammatory genes. Data shown are pooled from three biological repeats and are presented as mean (SEM); two-way ANOVA P_Interaction = 0.007 for Tnfrsf11b, P_Interaction = 0.0005 for Tnfa, P_Interaction < 0.0001 for all other genes; with post-hoc Sidak’s test *p < 0.05, **p < 0.01, and ***p < 0.001 versus control conditioned medium at that time point. OPG osteoprotegerin, RANKL receptor activator of nuclear factor kappa-B ligand, TNF tumor necrosis factor