Neonatal (perinatal) arterial ischemic stroke is as common as in the elderly and is a major cause of long-term neurological and cognitive deficits, including cerebral palsy and neurodevelopmental disabilities. Literature has emerged that the stage of brain development at the time of stroke has a major impact on the pathophysiological mechanisms of brain damage, but there are no effective treatments. Inflammation is a hallmark of perinatal brain injury and affects both early injury and brain repair and connectivity later in life. We discovered that microglia serve as endogenous protectants after acute stroke in neonatal rats and mice, including protection by removing apoptotic neuronal debris, limiting neuroinflammation and protecting blood-brain barrier integrity. We will determine whether microglial cells exert neuro- and vasoprotective effects via release of extracellular vesicles (EV). The fast-growing EV field as the fundamental way of cell-cell communication without direct cell-cell contacts in healthy and diseased organism has demonstrated heterogeneity of EV depending on the cell type releasing them, the mechanism of release and a neurodegenerative scenario. We hypothesize that microglial cells alleviate injury after neonatal stroke in part via released microglia- derived EV (MEV). In three aims, we will determine how neonatal stroke changes MEV properties and their communication with cells in brain slices and microglial cells that isolated after acute stroke (Aim 1); examine effects of disrupted lipid CD36-dependent signalling and disrupted EV release in the brain on neuroinflammation and injury in two mouse models?neonatal stroke or intracerebral IL1beta injection. We will analyse in vivo effects of halted EV release on neuronal and microglial transcriptome/proteome profiles in same injured neonatal brain (Aim 2); and determine if MEV administration early after neonatal stroke protects short-term and enhance long-term brain repair (Aim 3). To understand the mechanistic role of MEV and their therapeutic potential for neonatal stroke, we will utilize state-of-the art experimental tools, including a clinically relevant perinatal focal arterial stroke model that we invented, in conjunction with loss-of-function and gain-of function genetic and pharmacological approaches and advanced non-invasive imaging methodologies. We will manipulate EV release from neurons (CRISP editing approach), isolate and characterize individual EV and MEV fractions (super-sensitive ImageStreamX technology and MEV ?cargo?), image MEV communication with resting/activated microglia and the vasculature (live imaging), and utilize novel double transgenic RiboTag mice to examine in vivo real time microglia-neuron molecular crosstalk. The proposed studies will enhance the understanding of cell signalling and communication and help achieve our long-term goal to identify novel therapeutic targets to create effective and safe therapy for neonatal stroke.

Public Health Relevance

Stroke in the term newborn occurs in 1 in 4,000 live births. Most of these infants survive with significant long-term disabilities, and there are no treatments available to ameliorate their suffering and decrease the enormous cost to families and society. The proposed studies will identify previously unknown mechanisms of long-term repair of immature brain from stroke injury and discover new pharmacological targets to reduce brain injury in affected infants.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS044025-16
Application #
10025181
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Koenig, James I
Project Start
2002-09-01
Project End
2024-06-30
Budget Start
2020-07-01
Budget End
2021-06-30
Support Year
16
Fiscal Year
2020
Total Cost
Indirect Cost
Name
University of California San Francisco
Department
Neurology
Type
Schools of Medicine
DUNS #
094878337
City
San Francisco
State
CA
Country
United States
Zip Code
94118
Mallard, Carina; Ek, C Joakim; Vexler, Zinaida S (2018) The myth of the immature barrier systems in the developing brain: role in perinatal brain injury. J Physiol 596:5655-5664
Mallard, Carina; Tremblay, Marie-Eve; Vexler, Zinaida S (2018) Microglia and Neonatal Brain Injury. Neuroscience :
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Fernández-López, David; Faustino, Joel; Klibanov, Alexander L et al. (2016) Microglial Cells Prevent Hemorrhage in Neonatal Focal Arterial Stroke. J Neurosci 36:2881-93
Li, Fan; Faustino, Joel; Woo, Moon-Sook et al. (2015) Lack of the scavenger receptor CD36 alters microglial phenotypes after neonatal stroke. J Neurochem 135:445-52
Mallard, Carina; Vexler, Zinaida S (2015) Modeling Ischemia in the Immature Brain: How Translational Are Animal Models? Stroke 46:3006-11
Titomanlio, Luigi; Fernández-López, David; Manganozzi, Lucilla et al. (2015) Pathophysiology and neuroprotection of global and focal perinatal brain injury: lessons from animal models. Pediatr Neurol 52:566-584

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