Fig. 8

OMD inhibits osteoclastogenesis through its direct interaction with RANKL and balances bone remodeling. a Solid phase binding assay on the capture of RANKL by OMD. RANKL was coated on a plate followed by OMD addition. On the left: Binding assay with different concentrations of OMD (1 000 to 15.65 ng·mL⁻¹ by serial 2X dilution), with 0.2 μg·mL⁻¹ of coated RANKL (red curve) and negative control without RANKL (blue curve). On the right: Binding assay with different concentrations of coated RANKL (800 to 6.25 ng·mL⁻¹) and 0.5 μg·mL⁻¹ of given OMD (pink curve); negative control without OMD (purple curve). Wilcoxon test was performed with differences being considered significant at P values < 0.05 (*P < 0.05, **P ≤ 0.01). b Assay of the effect of OMD on primary murine osteoclast culture. The peripheral blood mononuclear cells were collected from murine bone marrow and differentiated into osteoclasts with M-CSF and RANKL. Osteoclasts were counted after 4 days of differentiation following a TRAP staining. Each point represents a mouse, n = 7. The osteoclast count was represented in percentage of cells with the corresponding control set as 100%. Blue arrows point at osteoclasts. Scale bar = 50 µm. The data were plotted as a box plot showing all points. One-way ANOVA was performed with differences being considered significant at P values <0.05 (*P < 0.05). c Level of P1NP and TRAcP 5b measured in the serum of KO, WT and UP mice. The data were plotted as a box plot showing all points with n = 12 for the KO and WT, and n = 10 for the UP. One-way ANOVA was performed when the distribution was Gaussian and Kruskal–Wallis was performed when the distribution was not Gaussian with differences being considered significant at P values < 0.05 (*P < 0.05, **P ≤ 0.01, ****P ≤ 0.000 1). d Schematic representation of the mechanism of OMD on osteoclastogenesis. Osteoblasts secrete RANKL which binds to the RANK receptor on the membrane of pre-osteoclasts to induce their differentiation into osteoclasts. In parallel, osteoblasts also secrete OMD which displays the ability to capture RANKL and would prevent its binding to RANK