TLR2 Elicits IL-17-Mediated RANKL Expression, IL-17, and OPG Production in Neutrophils from Arthritic Mice
Arthritis induced by intra-articular TLR2 ligand (zymosan; ZY) injection into BALB/c mice. (a) Representative photomicrographs of hematoxylin and eosin (H&E) stained ankle sections show cell infiltration (arrow, I) and cartilage erosion (arrows, E) at day 7 of zymosan injection (200 μg/10 μL per ankle) (magnification 40x). (b) Photomicrographs of Safranin O stained sections (magnification 100x) and scores for cell infiltration (I), proteoglycan loss (PG loss), and cartilage erosion indicates severe joint injury in zymosan-injected mice (ZY) in comparison to PBS-injected group (PBS). Values are the mean ± SEM (10 sections/mouse; mice/group; 5 experiments). ***, Kruskal-Wallis and Mann-Whitney U-test. (c) Increased IL-17 amounts in SF and serum of mice with arthritis (day 7). Bars show the mean ± SEM ( mice/group; 3 experiments). *; **, Student’s -test. (d) Cells accumulate in SF and frequencies of Ly6G+CD11b+ cells increase in SF and blood at day 7 of arthritis. Values are the mean ± SEM ( mice/group; 5 experiments). **; *** versus healthy (H) or versus PBS-injected groups (PBS), Student’s -test. (e) Blood and SF Ly6G+ cells upregulate surface CD69 at day 7 of arthritis. Values are the mean ± SEM ( mice/group; 3 experiments). **; ***, Student’s -test. MFI: mean fluorescence intensity.