Upregulations of IL-4 after focal ischemia-reperfusion injury and aggravation of brain ischemia by Il-4 silencing. (A) Schematic timeline of transient middle cerebral artery occlusion (tMCAO) in mice subjected to 1.5 h ischemia before reperfusion for 6, 12 or 24 h, and representative image of ischemic (Isc) and contralateral (Con) regions. Upregulation of Il-4 mRNA in the Isc region at 6 and 12 h after 1.5 h ischemia by real-time PCR analysis. (B) Upregulation of IL-4 protein expression in Isc at 24 h after reperfusion by Western blot analysis. (C) Representative local cerebral blood flow (LCBF) measured by laser Doppler flowmetry (LDF) in Il-4+/+ mouse (left) and Il-4−/− mouse (right) subject to I/R injury in tMCAO model. Red arrows indicate insertion and withdrawal of the filament. (D) Representative images of TTC-stained brain slices at 24 h after reperfusion from Il-4+/+ and Il-4−/− male mice. The white regions indicate the infarct size, and regions in red indicate the viable tissues. An increase of infarct volume (%) and neurological deficit scores in male Il-4−/− mice subjected to I/R injury. Data are presented as the median ± 95% CI, ∗∗∗P < 0.001, ∗∗∗∗P < 0.0001 versus Il-4+/+ group for Mann Whitney test. Other data are presented as the mean ± SEM. The numbers at the bottom of the bars indicate the number of repeats or mice in each group, ∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001.