TLR2 Elicits IL-17-Mediated RANKL Expression, IL-17, and OPG Production in Neutrophils from Arthritic Mice
Ly6G+CD11b+ cells from arthritic mice produced IL-17 and IFN-γ. Purified blood neutrophils were cultured (1 × 106/mL) in medium with GM-CSF (50 ng/mL) and stimulated with zymosan (20 μg/mL) or/and IL-17 (40 ng/mL) for 24 hours. Intracellular IL-17 and IFN-γ production was evaluated by flow cytometry. (a) Ly6G+CD11b+ cells were IFN-γ −/IL-17− as shown on dot-plot histograms and graphs. IL-17 induces autocrine IL-17 protein expression and IFN-γ synthesis in control cells. (b) Dot-plot histograms and graphs show spontaneous IL-17 and IFN-γ production by Ly6G+CD11b+ cells from arthritic group. Zymosan provides stronger signals for IL-17 synthesis than exogenous IL-17 and amplifies the generation of IL-17+ cells. Bars on graphs (a) and (b) represent the mean ± SEM ( animals/group; 3 experiments). *; **; ***, Student’s -test.