Mrgprb2 mediated neuroinflammation after cerebral ischemia

ABSTRACT I am finishing my cerebrovascular fellowship in the department of neurosurgery at the Johns Hopkins School of Medicine, where I will start as an assistant professor of neurosurgery with a practice focused on cerebrovascular diseases. I am applying for a mentored surgeon-scientist career development award (CDA) to obtain further training in neuroscience, immunology, and animal models of cerebral ischemia. This will further my long-term career goals of exploring neuro-immunologic mechanisms underlying cerebral ischemia, and hopefully provide a basis for new investigations in patients experiencing ischemic stroke. A major mechanism underlying stroke pathology involves neuroinflammation, where activation of microglia and infiltration of peripheral leukocytes worsen neuronal injury and cell death. Despite substantial pre- clinical efforts, there exists no efficacious therapeutic in limiting post-stroke neuroinflammatory damage. Mast cells are tissue specific, long-lived immunologic effector cells which are thought to be one of the first-responders in immune surveillance and activation, activating multiple pathways of the innate immune system. As such, the ability to suppress mast cell activation may broadly attenuate multiple pathways of cerebral inflammation after stroke. Recently, Mrgprb2 was identified as a mast cell-specific G-coupled protein receptor for basic secretagogues, mediating IgE-independent activation. I have shown preliminarily that deletion of Mrgprb2 results in decreased stroke volume after transient middle cerebral artery occlusion (tMCAO), with decreased transcription and production of TNFa and CCL2 after stroke, and decreased neutrophil recruitment into the ischemic brain. This CDA proposes building upon my pharmacology graduate training in mechanisms of cell death and cocaine addiction, towards a new direction at the interface of neuroscience and immunology. I hope this CDA will allow me to receive multidisciplinary training in the Departments of Neuroscience and Cellular and Molecular Medicine. Specific training goals include: (1) Training in advanced basic neuroscience techniques including dural and meningeal microdissection, and in-vivo live-animal imaging (2) Training in animal models of cerebral ischemia including photo-thrombotic stroke (3) Didactic and experimental training in immunology and neuro-immune interactions (4) Additional training in the ethical and responsible conduct of research. The research plan seeks to address the hypothesis that Mrgprb2 is a critical mast cell specific receptor which upregulates the initial immunologic activation response after cerebral ischemia, and that inhibition of the physiologic ligand for Mrgprb2 may decrease neuroinflammation after stroke. The Specific Aims of the proposal are to: (1) Investigate which subset of mast cell mediators are regulated by Mrgprb2 in ischemic stroke (2) Determine the localization and expression pattern of Mrgprb2 in central nervous system mast cells (3) Find the endogenous ligand for Mrgprb2 in cerebral ischemia by screening of known Mrgprb2 agonists after tMCAO, along with testing of inhibitors of Mrgprb2 as potential therapeutics of stroke.