Recombinant Slit2 Reduces Brain Water Content And Attenuates Neurobehavioral Deficits Following Intracerebral Hemorrhage In A Murine Model

Introduction and Hypothesis: Intracerebral hemorrhage (ICH) remains the least treatable and most fatal stroke subtype, being associated with significant vascular disruption, which leads to edema development and the recruitment of inflammatory agents. Slit2, one of a family of three large secreted proteins, has been found to regulate cell proliferation, adhesion, and migration through its receptor, roundabout (Robo)1. We have previously found that administration of recombinant Slit2 (rSlit2) improved outcomes after surgical brain injury. Thus, we hypothesized that Slit2, through the Robo1 receptor, could mitigate ICH-induced neuroinflammation by reducing leukocyte migration, thereby decreasing brain water content (BWC), and improving neurobehavior. Methods: ICH was induced in CD-1 mice by collagenase infusion, as previously established. To determine the expression of Slit2 and Robo1 after ICH, a time course profile (3, 6, 12, 24, and 72 hours) of both proteins was developed by Western Blotting. Then, animals were randomly divided into 5 groups: sham, vehicle, 3μg/kg rSlit2, 10μg/kg rSlit2, and 30μg/kg rSlit2. rSlit2 was administered 1h after ICH, and BWC and neurobehavior assessed at 24 and 72 hours. Western blots and immunohistochemistry will be done to evaluate leukocyte infiltration and other inflammatory markers. Results: Endogenous Slit2 and Robo1 were initially decreased, and then increased after ICH, in comparison to sham. Treatment with rSlit2 significantly reduced brain water content at 24 hours and improved neurological scores. At 72h, there was a tendency for improved brain water content and neurobehavior. We further anticipate that rSlit2 treatment will attenuate leukocyte migration to the injury site, as well as inhibit other pro-inflammatory signals, and these through its action on Robo1. Conclusions: Recombinant Slit2 improved outcomes after murine ICH (BWC and neurological deficits). We expect that this occurs through the inhibition of inflammatory signaling.