TLR2 Elicits IL-17-Mediated RANKL Expression, IL-17, and OPG Production in Neutrophils from Arthritic Mice
Depletion of Ly6G+CD11b+ cells with monoclonal 1A8 antibody (Ab). (a) SCID mice were injected intraperitoneally (i.p) with 1A8 Ab (100 μg/mouse) at days −2, +2, and +4 (arrows showing the injections). The mice received intra-articular (i.a.) knee injection of PBS (10 μL; naive) or zymosan (200 μg/10 μL; arrow ZY) at day 0. Flow cytometry analysis indicates the loss of Ly6G+CD11b+ cells in BM after Ab treatments. Values are the mean ± SEM ( mice/group), Student’s -test. (b) At day 7 of TLR2 ligand injection (or 3 days after the last 1A8 Ab administration) Ly6G+CD11b+ cells partially recover in BM but are completely lost in blood and SF of 1A8 Ab-treated mice. Bars indicate the mean ± SEM ( mice/group). *; **; ***, Student’s -test. (c) The administration of 1A8 Ab attenuates joint damages as shown on the representative photomicrographs (magnification 100x) and by histological scores for cell infiltration (I), proteoglycan (PG) loss, and percentages of cartilage erosion. Values are the mean ± SEM ( mice/group). **; ***, Kruskal-Wallis test and Mann-Whitney U-test. Ly6G+ cell depletion decreases the amounts of RANKL (d), IL-17 (e), and OPG (f) in serum and SF of ZY mice. Values in (d), (e), and (f) are the mean ± SEM ( animals/group). *; **; ***, Student’s -test.