Fig 1: IRG1 deficiency exacerbates BBB disruption in ischaemic stroke. (A) WT and IRG1−/− mice were subjected to the measurement of CBF before and during sham (n = 3 mice per group) and MCAO surgeries (n = 6–7 mice per group). The representative CBF images of WT and IRG1−/− sham and MCAO mice are shown, and the percentage of CBF reduction (CBF reading during occlusion/CBF reading before occlusion) in the contralateral (C) and ipsilateral (I) hemispheres were calculated. (B) WT and IRG1−/− mice were subjected to sham (n = 3 mice per group) or 3 h MCAO (n = 6–7 mice per group) followed by 3.5 h reperfusion. One hour before scarification, mice were intravenously injected with Evans blue. At 6.5 h post-injury, the ischaemic brains were then harvested and subjected to sectioning and imaging, and the Evans blue leakage in the contralateral and ipsilateral hemispheres was then quantified. The representative ischaemic brain images of WT and IRG1−/− sham and MCAO mice are shown, and the Evans blue extravasation ratio of ipsilateral (Ipsi.) hemisphere/contralateral (Cont.) hemisphere was determined. A: anterior surface; P: posterior surface. *P < 0.05, N.S., no significant differences by one-way ANOVA. (C) WT and IRG1−/− mice were subjected to 3 h MCAO followed by 3.5 h reperfusion (n = 6 mice per group). The ipsilateral hemispheres of ischaemic brains were then harvested and subjected to western blot analysis for MMP9 and MMP3 expression. The level of MMP9 and MMP3 expression was also quantified. ***P < 0.001 by unpaired t-test. (D) WT and IRG1−/− mice were subjected to sham or 40 min MCAO surgery. Twenty-four hours post-injury, mononuclear cells were isolated from the contralateral (C) and ipsilateral (I) hemispheres of WT and IRG1−/− sham (n = 3 mice per group) and MCAO mice (n = 8 mice per group). The isolated cells were then stained with antibodies against CD45 and CD11b followed by flow cytometry analysis. The CNS infiltrating immune cells were determined based on their high expression of CD45 and positive expression of CD11b (CD45hiCD11b+). **P < 0.01, N.S., no significant differences by two-way ANOVA.