Plasmin drives MMP-9 upregulation worsens clinical outcome in CpG/DG-injeceted MAS mice. (A) Blood samples retrieved 50 hours after CpG/DG injection from control and CpG/DG-injected mice treated with PBS or YO-2 were analyzed by gelatin zymography. Right panels, The quantification of the intensity of pro MMP-9, active MMP-9, active MMP-2, and total MMP-2 bands were analyzed by comparing to the bands of untreated mice (n = 3 per group). (B) Total plasma MMP-9 levels of untreated mice and CpG/DG-injected mice treated with PBS or with YO-2 at indicated time points (n = 5-7 per group). (C) Representative images of MMP-9 immunostained liver sections derived from untreated mice and CpG/DG-injected mice treated with PBS or YO-2 at day 4. Scale bars = 200 μm. Black arrows indicate MMP-9⁺ cells. Right panel, The quantification of MMP-9⁺ cells in liver sections from untreated and CpG/DG-injected mice treated with PBS or YO-2 at day 4 (n = 5 per group). (D) Survival rate of CpG/DG-injected Mmp9^+/+ or Mmp9^−/− mice (n = 12 per group). (E) Percentage of blood counts of CpG/DG-injected Mmp9^+/+ or Mmp9^−/− mice at day 10 (n = 6-8 per group) (set as 100% for day 0). (F) Spleen cell number from CpG/DG-injected Mmp9^+/+ or Mmp9^−/− mice at day 0 and 10 (n = 5 per group). (G) Representative images of H&E-stained liver sections of CpG/DG-injected Mmp9^+/+ or Mmp9^−/− mice at day 0, 4, and 10. Scale bars = 200 μm. Black dotted lines indicate mononuclear cell infiltration; blue arrows, hepatocellular degeneration. Bottom panel, histopathological scores of CpG/DG-injected Mmp9^+/+ or Mmp9^−/− mice at day 4 and 10 (n = 5 per group). (H) Representative images of H&E-stained BM sections of CpG/DG-injected Mmp9^+/+ or Mmp9^−/− mice at day 0 and day 10. Bars represent 200 μm. Data represent mean ± SEM. *P < .05, **P < .01, ***P < .001, using 1-way ANOVA with the Tukey posttest or the unpaired, 2-tailed Student t test for significance and using the log-rank test for survival curves. HPF, high-powered field.