Evidence that the EphA2 receptor exacerbates ischemic brain injury

PLoS One. 2013;8(1):e53528. doi: 10.1371/journal.pone.0053528. Epub 2013 Jan 7.

Abstract

Ephrin (Eph) signaling within the central nervous system is known to modulate axon guidance, synaptic plasticity, and to promote long-term potentiation. We investigated the potential involvement of EphA2 receptors in ischemic stroke-induced brain inflammation in a mouse model of focal stroke. Cerebral ischemia was induced in male C57Bl6/J wild-type (WT) and EphA2-deficient (EphA2(-/-)) mice by middle cerebral artery occlusion (MCAO; 60 min), followed by reperfusion (24 or 72 h). Brain infarction was measured using triphenyltetrazolium chloride staining. Neurological deficit scores and brain infarct volumes were significantly less in EphA2(-/-) mice compared with WT controls. This protection by EphA2 deletion was associated with a comparative decrease in brain edema, blood-brain barrier damage, MMP-9 expression and leukocyte infiltration, and higher expression levels of the tight junction protein, zona occludens-1. Moreover, EphA2(-/-) brains had significantly lower levels of the pro-apoptotic proteins, cleaved caspase-3 and BAX, and higher levels of the anti-apoptotic protein, Bcl-2 as compared to WT group. We confirmed that isolated WT cortical neurons express the EphA2 receptor and its ligands (ephrin-A1-A3). Furthermore, expression of all four proteins was increased in WT primary cortical neurons following 24 h of glucose deprivation, and in the brains of WT mice following stroke. Glucose deprivation induced less cell death in primary neurons from EphA2(-/-) compared with WT mice. In conclusion, our data provide the first evidence that the EphA2 receptor directly contributes to blood-brain barrier damage and neuronal death following ischemic stroke.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blood-Brain Barrier / metabolism
  • Blood-Brain Barrier / pathology
  • Brain Infarction / genetics*
  • Brain Infarction / metabolism
  • Brain Infarction / pathology
  • Brain Ischemia / genetics*
  • Brain Ischemia / metabolism
  • Brain Ischemia / pathology
  • Caspase 3 / genetics
  • Caspase 3 / metabolism
  • Cerebral Cortex / metabolism*
  • Cerebral Cortex / pathology
  • Ephrins / genetics
  • Ephrins / metabolism
  • Gene Expression Regulation
  • Glucose / deficiency
  • Infarction, Middle Cerebral Artery / pathology
  • Male
  • Matrix Metalloproteinase 9 / genetics
  • Matrix Metalloproteinase 9 / metabolism
  • Mice
  • Neurons / metabolism*
  • Neurons / pathology
  • Receptor, EphA2 / deficiency
  • Receptor, EphA2 / genetics*
  • Reperfusion Injury / pathology
  • Signal Transduction
  • Tetrazolium Salts
  • Zonula Occludens-1 Protein / genetics
  • Zonula Occludens-1 Protein / metabolism
  • bcl-2-Associated X Protein / genetics
  • bcl-2-Associated X Protein / metabolism

Substances

  • Ephrins
  • Tetrazolium Salts
  • Tjp1 protein, mouse
  • Zonula Occludens-1 Protein
  • bcl-2-Associated X Protein
  • triphenyltetrazolium
  • Receptor, EphA2
  • Caspase 3
  • Matrix Metalloproteinase 9
  • Glucose

Grants and funding

This work was supported by the ARC Future Fellowship (FT100100427) awarded to TVA. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.