Fig. 4

S100a9^-/- mice have locally more Ly6C^low monocytes in early collagenase-induced osteoarthritis (CiOA), compared to wild-type (WT) mice at CiOA day 7. a, b Less influx of inflammatory cells in S100a9^-/- (a) mice compared to WT mice (b) at CiOA day 7, as shown by HE staining. c mRNA expression of the Ly6C^low monocyte-subset-attracting chemokine CX3CL1 is increased in the synovium of S100a9^-/- mice compared to WT mice at CiOA day 7, while Ly6C^high monocyte-subset-attracting chemokine CCL2 and both monocyte subset cell markers CCR2 (Ly6C^high) and CX3CR1 (Ly6C^low) were not different between the two strains. d Relative number of Ly6C^high monocytes are increased locally in the joint of WT mice, whereas Ly6C^low monocytes are increased in S100a9^-/- mice, compared to saline-injected controls, as analyzed by flow cytometry. Data represent mean ± SD of five individual mice per group. *Significantly different from saline-injected control (*p < 0.05, ***p < 0.001)