FIGURE 3.

Enhanced induction of MMP9 in STAT3-deficient BMDM upon stimulation with S. aureus. STAT3 WT and KO BMDM were stimulated with vcl, LPS (100 ng/ml), IL-4 (20 ng/ml), or S. aureus (MOI 10). During the stimulation, penicillin-streptomycin was added at 2 h to all conditions to kill off viable S. aureus. At 24 or 48 h, supernatants were harvested for cytokine analysis by ELISA. In selected experiments, BMDM were subjected to RNA extraction by the TRIzol method. After generation of cDNA, qPCR analysis was performed. (A and B) Pro-MMP9 levels by ELISA at (A) 24 h and (B) 48 h after stimulation. (C and D) MMP9 RNA expression at (C) 24 h and (D) 48 h. (E and F) TIMP1 levels by ELISA at (E) 24 h and (F) 48 h after stimulation. (G and H) TIMP1 RNA expression at (G) 24 h and (H) 48 h. (I and J) Calculated ratio of pro-MMP9/TIMP1 protein levels by ELISA at (I) 24 h and (J) 48 h. Pooled data (mean with SEM) from n ≥ 3 different experiments are shown. (A–H) All data with more than two variables were analyzed by employing the mixed-effects model with Bonferroni analysis for multiple comparisons. (I and J) Pro-MMP9/TIMP1 protein ratio was analyzed with a nonparametric Mann–Whitney test. p > 0.05 not significant; *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001.