Type I interferon mediated restoration of brain endothelial cell function after cerebral infarction

PROJECT SUMMARY/ABSTRACT Vascular remodeling and restoration of blood-brain barrier (BBB) function are critical for the reestablishment of a microenvironment that supports tissue repair and functional recovery after ischemic stroke. During development, Wnt/β-catenin signaling functions to tightly couple central nervous system (CNS) angiogenesis to barriergenesis. However, there is a critical gap in knowledge regarding the underlying mechanisms that mediate restoration of vascular homeostasis after ischemic injury. Damage-associated molecular patterns, released from dying cells during ischemic brain injury, trigger an inflammatory response which can either promote or exacerbate tissue repair. The plasticity of this response thus represents a promising therapeutic target, but this clinical potential is hindered by an incomplete understanding of how sterile inflammation regulates vascular repair. My preliminary data demonstrate that cerebral infarction triggers a local upregulation of type I interferon (IFN1) signaling that is temporally aligned with the induction of peri-infarct angiogenesis, Wnt/β-catenin signaling, and peripheral immune cell infiltration. This data is compelling when viewed together with previous work showing that IFN1 signaling regulates peripheral vascular maturation, BBB integrity, and immune cell recruitment in the context of other diseases. However, the impact of endogenous IFN1 signaling on vascular repair after ischemic brain injury is unknown. The central hypothesis of this proposal is that upregulation of IFN1 signaling by ischemic brain injury coordinates vascular remodeling and restoration of hemodynamic function by acting 1) directly on brain endothelial cells (BECs) to restore BBB function and 2) indirectly through recruitment of peripheral monocytes and activated microglia to promote angiogenesis. This hypothesis will be tested using a combination of genetic, molecular, computational approaches, and in vivo functional imaging of the rodent brain with swept, confocally aligned planar excitation (SCAPE) and two photon microscopy. Aim 1 will determine how IFN1 signaling in BECs and CNS myeloid cells regulates angiogenesis, barriergenesis and the innate immune response after cerebral infarction. Aim 2 will establish a robust in vivo paradigm for mapping the natural trajectory of cerebrovascular function after ischemic brain injury and determine the impact of BEC and CNS myeloid cell IFN1 signaling on longitudinal vascular function. The proposed studies will elucidate the mechanisms by which IFN1 signaling impacts vascular plasticity after ischemic brain injury and will establish a novel technical framework for the molecular investigation and functional validation of candidate therapeutic targets. This knowledge will enhance our understanding of how sterile inflammatory pathways regulate vascular repair after ischemic stroke and has the potential to guide future therapeutic interventions to improve functional outcomes after brain ischemia.