Research ReportPharmacologic blockade of vascular adhesion protein-1 lessens neurologic dysfunction in rats subjected to subarachnoid hemorrhage

- Enhanced leukocyte trafficking contributes to early brain injury post subarachnoid hemorrhage.
- VAP-1 blockade attenuated leukocyte trafficking and improved neurological outcome after SAH.
- Specific leukocyte subsets involved in leukocyte trafficking after SAH remains to be elucidated.

Aneurysmal subarachnoid hemorrhage (SAH) is a potentially devastating clinical problem. Despite advances in the diagnosis and treatment of SAH, outcome remains unfavorable. An increased inflammatory state, one that is characterized by enhanced leukocyte trafficking has been reported to contribute to neuronal injury in association with multiple brain insults, including hemorrhagic and ischemic stroke. This study was designed to investigate, in rats, the neuropathologic consequences of heightened leukocyte trafficking following SAH, induced via endovascular perforation of the anterior cerebral artery. Experiments focused on the initial 48 h post-SAH and sought to establish whether blockade of vascular adhesion protein-1 (VAP-1), with LJP-1586, was able to provide dose-dependent neuroprotection. Treatment with LJP-1586 was initiated at 6 h post-SAH. An intravital microscopy and closed cranial window system, that permitted examination of temporal patterns of rhodamine-6G-labeled leukocyte adhesion/extravasation, was used. Effects of LJP-1586 on neurologic outcomes and leukocyte trafficking at 24 h and 48 h post-SAH were examined. In VAP-1-inhibited vs control rats, results revealed a significant attenuation in leukocyte trafficking at both 24 h and 48 h after SAH, along with an improvement in neurologic outcome. In conclusion, our findings support the involvement of an amplified inflammatory state, characterized by enhanced leukocyte trafficking, during the first 48 h after SAH. VAP-1 blockade yielded neuroprotection that was associated with an attenuation of leukocyte trafficking and improved neurologic outcome.