Depletion of Ly6G/C+ cells ameliorates delayed cerebral vasospasm in subarachnoid hemorrhage

Background: The etiology of delayed cerebral vasospasm (DCV) after aneurysmal subarachnoid hemorrhage (SAH) has remained elusive. Growing evidence supports a role for inflammation in the pathogenesis of DCV. We showed that CSF neutrophils predict which patients will develop DCV. Methods: We evaluated a murine model of SAH to test the hypothesis that myeloid cells are required for the cerebral damage associated with DCV. Results: SAN was associated with decreased middle cerebral artery caliber on day 1 which normalized at day 3 and recurred at day 6. In addition, behavioral testing with a Barnes maze showed executive dysfunction that progressively worsened after the seventh day post hemorrhage. To test the role of innate immune responses, we administrated a myeloid cell-depleting monoclonal antibody against Ly6G/C prior to experimental SAH. Myeloid cell depletion ameliorated angiographic vasospasm measured by MCA vessel caliber and normalized behavioral testing. Conclusion: Our findings support the role of Ly6G/C+ cells in the development of DCV after SAN and suggest that immune modulation of neutrophils or other Ly6G/C+ cells may be a strategy for the prevention of DCV. (C) 2010 Elsevier B.V. All rights reserved.