Fig. 2

C-C motif chemokine receptor 4 (CCR4) is required for collagenase-induced osteoarthritis (CiOA) pain and optimal disease development. CiOA was induced in wild-type (WT) and Ccr4^−/− mice. a Pain (change in weight distribution; see “Methods”) was monitored over time. b Representative histologic pictures of knee joints (Safranin O/fast green stain, original magnification ×100) and quantification of arthritis at day 42. c Representative histologic pictures of osteophytes (indicated by arrow) (Safranin O/fast green stain; original magnification ×100) and quantification of osteophyte size. Results are expressed as the mean ± SEM; n = 5 mice per strain. i.a., intra-articular. *p < 0.05, **p < 0.01, ***p < 0.001, WT vs. Ccr4^−/− mice