Fig. 1: MiR-21 deficiency exacerbates inflammatory responses in heart after MI.

a Q-PCR analysis of Il1b, Il6, and Tnf mRNA in heart tissues from sham group or remote area (RA) or border area (BA) from miR-21 knockout (KO) or wild-type (WT) mice at the indicated days after MI. Expression levels were presented as relative fold values compared to sham group (determined as 1 for each gene at the indicated days) after normalization to GAPDH. Data represent the mean ± SEM (n = 5 mice per group). **P < 0.01 vs. corresponding WT-MI-BA (two-way ANOVA). b Immunohistochemical staining of IL-1β, IL-6, and TNF-α expression in heart sections of border areas from miR-21 KO or WT mice at day 3 after MI. Scale bars = 50 μm. c Immunofluorescence staining of IL-1β (green) and CD11b (red) in heart sections of border areas from miR-21 KO or WT mice at day 3 after MI. Scale bars = 50 μm. d Quantification of IL-1β-positive cells was presented as a percentage of total CD11b⁺ cells counted. Data represent the mean ± SEM (n = 5 mice per group). **P < 0.01 vs. WT (Student’s t-test). e Q-PCR analysis of Il1b, Il6, and Tnf mRNA in CD11b⁺ monocytes/macrophages isolated from the border/infarct areas of cardiac tissues of miR-21 KO and WT mice at day 3 after MI or left-ventricular anterior wall from sham group mice. Expression levels were presented as relative fold values compared to sham group (determined as 1 for each gene) after normalization to GAPDH. Data represent the mean ± SEM (n = 5 mice per group). *P < 0.05 vs. WT (two-way ANOVA). f Survival curve of miR-21 KO or WT mice subjected to MI or sham operation (n = 16 mice per group). *P < 0.05 vs. WT-MI (log‐rank test)