Plasmin induces BBB leakage in a bradykinin B2 receptor–dependent manner. (A) Schematic representation of the known effects of plasmin and corresponding inhibitors. (B) Experimental design performed to study BBB permeability, using NIRF techniques. EB extravasation was measured ex vivo 48 hours after pLIVE (0 or tPA) transfection in the brain. (C) Fluorescence images of pLIVE-tPA-transfected animals, showing that neither the blockade of NMDA-R (MK-801) or PAR-1 (SCH-79797) nor matrix metalloproteinases (CP-471474) prevented BBB leakage (n = 5 per group). Only icatibant (bradykinin B2 receptor inhibitor) prevented plasmin-dependent BBB leakage in hyperfibrinolytic mice. (D) Mean brain water contents (%) at +48 hours of pLIVE-0- and pLIVE-tPA-transfected mice treated or not with icatibant (0.5 mg every 12 hours; n = 10 per group). (E) Mean spontaneous locomotor activities (vertical moves), expressed as ratios between +48 hours and immediately before hydrodynamic transfections of pLIVE-0- and pLIVE-tPA-transfected mice treated or not with icatibant (0.5 mg every 12 hours; n = 10 per group). *P < .05 vs control; ns, nonsignificant differences.