Microglial P2Y12 Deficiency/Inhibition Protects against Brain Ischemia
Objective: Microglia are among the first immune cells to respond to ischemic insults. Triggering of this inflammatory response may involve the microglial purinergic GPCR, P2Y 12 , activation via extracellular release of nucleotides from injured cells. It is also the inhibitory target of the widely used antiplatelet drug, clopidogrel. Thus, inhibiting this GPCR in microglia should inhibit microglial mediated neurotoxicity following ischemic brain injury. Methods: Experimental cerebral ischemia
... s induced, in vitro with oxygen-glucose deprivation (OGD), or in vivo via bilateral common carotid artery occlusion (BCCAO). Genetic knock-down in vitro via siRNA, or in vivo P2Y 12 transgenic mice (P2Y 12 2/2 or P2Y 12 +/2), or in vivo treatment with clopidogrel, were used to manipulate the receptor. Neuron death, microglial activation, and microglial migration were assessed. Results: The addition of microglia to neuron-astrocyte cultures increases neurotoxicity following OGD, which is mitigated by microglial P2Y 12 deficiency (P,0.05). Wildtype microglia form clusters around these neurons following injury, which is also prevented in P2Y 12 deficient microglia (P,0.01). P2Y 12 knock-out microglia migrated less than WT controls in response to OGD-conditioned neuronal supernatant. P2Y 12 (+/2) or clopidogrel treated mice subjected to global cerebral ischemia suffered less neuronal injury (P,0.01, P,0.001) compared to wild-type littermates or placebo treated controls. There were also fewer microglia surrounding areas of injury, and less activation of the pro-inflammatory transcription factor, nuclear factor Kappa B (NFkB). Interpretation: P2Y 12 participates in ischemia related inflammation by mediating microglial migration and potentiation of neurotoxicity. These data also suggest an additional anti-inflammatory, neuroprotective benefit of clopidogrel. Citation: Webster CM, Hokari M, McManus A, Tang XN, Ma H, et al. (2013) Microglial P2Y 12 Deficiency/Inhibition Protects against Brain Ischemia. PLoS ONE 8(8): e70927.