AMPA-Kainate Receptor Inhibition Promotes Neurologic Recovery in Premature Rabbits with Intraventricular Hemorrhage

Abstract

Intraventricular hemorrhage (IVH) in preterm infants leads to cerebral inflammation, reduced myelination of the white matter, and neurological deficits. No therapeutic strategy exists against the IVH-induced white matter injury. AMPA-kainate receptor induced excitotoxicity contributes to oligodendrocyte precursor cell (OPC) damage and hypomyelination in both neonatal and adult models of brain injury. Here, we hypothesized that IVH damages white matter via AMPA receptor activation, and that AMPA-kainate receptor inhibition suppresses inflammation and restores OPC maturation, myelination, and neurologic recovery in preterm newborns with IVH. We tested these hypotheses in a rabbit model of glycerol-induced IVH and evaluated the expression of AMPA receptors in autopsy samples from human preterm infants. GluR1-GluR4 expressions were comparable between preterm humans and rabbits with and without IVH. However, GluR1 and GluR2 levels were significantly lower in the embryonic white matter and germinal matrix relative to the neocortex in both infants with and without IVH. Pharmacological blockade of AMPA-kainate receptors with systemic NBQX, or selective AMPA receptor inhibition by intramuscular perampanel restored myelination and neurologic recovery in rabbits with IVH. NBQX administration also reduced the population of apoptotic OPCs, levels of several cytokines (TNF␣, IL-␤, IL-6, LIF), and the density of Iba1 ϩ microglia in pups with IVH. Additionally, NBQX treatment inhibited STAT-3 phosphorylation, but not astrogliosis or transcription factors regulating gliosis. Our data suggest that AMPA-kainate receptor inhibition alleviates OPC loss and IVH-induced inflammation and restores myelination and neurologic recovery in preterm rabbits with IVH. Therapeutic use of FDA-approved perampanel treatment might enhance neurologic outcome in premature infants with IVH. Key words: AMPA; myelination; NBQX; oligodendrocyte; perampanel Significance StatementIntraventricular hemorrhage (IVH) is a major complication of prematurity and a large number of survivors with IVH develop cerebral palsy and cognitive deficits. The development of IVH leads to inflammation of the periventricular white matter, apoptosis and arrested maturation of oligodendrocyte precursor cells, and hypomyelination. Here, we show that AMPA-kainate receptor inhibition by NBQX suppresses inflammation, attenuates apoptosis of oligodendrocyte precursor cells, and promotes myelination as well as clinical recovery in preterm rabbits with IVH. Importantly, AMPA-specific inhibition by the FDA-approved perampanel, which unlike NBQX has a low side-effect profile, also enhances myelination and neurological recovery in rabbits with IVH. Hence, the present study highlights the role of AMPA-kainate receptor in IVH-induced white matter injury and identifies a novel strategy of neuroprotection, which might improve the neurological outcome for premature infants with IVH.

Human Cord Blood-Derived Unrestricted Somatic Stem Cell Infusion Improves Neurobehavioral Outcome in a Rabbit Model of Intraventricular Hemorrhage

“…To determine whether USSCs affected cytokine expression in IVH‐induced inflammation, we measured mRNA expression of relevant cytokines in our rabbit model of IVH: IL1‐β and TNFα using qPCR. Consistent with our previous reports, the mRNA levels of IL1‐β and TNF‐α were significantly elevated in pups with IVH compared with no IVH controls at day 3 (Fig. D, E; p < .05).…”

“… In our previous studies, we demonstrated suppression of inflammation followed by improved myelination and less gliosis using various pharmacological approaches indicating some degree of injury was reversible. Therefore, in the present study, we examined the same regions of the CR and CC (Fig. S4).…”

Current Evidence on Cell Death in Preterm Brain Injury in Human and Preclinical Models

“…Increased cell death and apoptosis have been evidenced by TUNEL staining and CASP3 activation in the periventricular WM (Dummula et al, 2011;Ahn et al, 2013;Gram et al, 2014;Dohare et al, 2016;Mukai et al, 2017) and adjacent GM [striatum (Xue et al, 2003) or cortex (Georgiadis et al, 2008;Zia et al, 2009;Vinukonda et al, 2010)]. However, the identification of the dying cells has not been determined except in some studies showing that cell death (Fluoro-Jade+ cells) could affect O4+ pre-oligodendrocytes or neurons.…”

Challenges for intraventricular hemorrhage research and emerging therapeutic targets

“…thrombin, fibrinogen, hemoglobin). After IVH there is an upregulation of pro-inflammatory cytokines, microglial activation and leukocyte infiltration into brain 110, 111 . Microglia are the resident brain immune cells that upon activation can have a range of phenotypes.…”