Figure 4

u-PA^-/- mice develop increased antigen-induced arthritis. Mice were sacrificed at 0, 1, 2, and 6 weeks after intra-articular (i.a.) injection. (a) Macroscopic knee score. Quantification of (b) cellular infiltration and (c) bone erosions in knee joints. (d) Representative histological pictures (hematoxylin and eosin) of knee joints. Results are expressed as the mean ± standard error of the mean (five mice per group). *P < 0.05, **P < 0.01, ***P < 0.001, ^#P < 0.0001, C57BL/6 versus u-PA^-/- mice; P = 0.0001, C57BL/6 macroscopic knee score over time; P = 0.007, C57BL/6 cellular infiltration over time; P < 0.05, C57BL/6 or u-PA^-/- bone erosion over time. mBSA, methylated bovine serum albumin; u-PA^-/-, urokinase-type plasminogen activator gene-deficient.