Fig. 5

Increased S100A8 expression is associated with increased MMP activity in the inflamed ankle joints. a Increased expression of S100A8 in the inflamed ankle joints in 16-week-old IL-1Ra^–/– mice was associated with increased VDIPEN staining around the chondrocytes and cartilage matrix of the articular cartilage. Isotype control IgG staining for VDIPEN staining showed no staining in ankle joint sections of arthritic IL-1Ra^–/– mice (insert). b Intravenous injection of the MMP inhibitor AF-489 coupled to Cy5.5 led to an increased fluorescent signal in the inflamed ankle joints of arthritic IL-1Ra^–/– mice and the observed fluorescent signal correlated to the macroscopic score for joint swelling (macroscopic score for joint swelling in white). Ig immunoglobulin, IL-1Ra interleukin-1 receptor antagonist, SNR signal-to-noise ratio, Ta talus, Ti tibia