Figure 4. Inhibition of ERK1/2 activation attenuates myocardial remodeling and inflammation in permanent MI.

Trametinib- and vehicle-treated mice were studied for 7 days after permanent LAD ligation. (A) Relative mRNA expression analysis of Il6, Tnf, Ccl2, and Ccr2 from the infarcted myocardium. (B) Flow cytometry analysis of the infarcted myocardium obtained from vehicle- or trametinib-treated mice normalized to heart weight. Representative gating strategies for quantification of CD45⁺ leukocytes: CD45⁺CD90.2^–B220^–NK1.1^–CD11b⁺ myelomonocytic cells, CD45⁺CD90.2^–B220^–NK1.1^–CD11b⁺Ly6G^–F4/80^–Ly6C^hi monocytes, and CD45⁺CD90.2^–B220^–NK1.1^–CD11b⁺Ly6G^–F4/80^–Ly6C^lo macrophages. (C) Protein expression analysis of p-ERK1/2 (normalized to total ERK1/2) and activated TGF-β1 (normalized to GAPDH) in infarcted myocardium obtained from vehicle- or trametinib-treated mice. IOD, integrated optical density. (D) Protein expression analysis of p-ERK1/2 (normalized to ERK1/2) and activated TGF-β1 (normalized to GAPDH) in PBMCs isolated from vehicle- or trametinib-treated mice. Ordinary 1-way ANOVA, Šidák’s multiple-comparison test; n = 4–6 animals per group. Data are shown as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.