Microglia transcriptome in a rat model of ischemic stroke

Microglia are key regulators of inflammatory response after stroke and brain injury. Here we profiled the microglia transcriptome isolated from a spontaneously hypertensive rat model of focal cerebral ischemia. We identified an extensive and persistent upregulation of anti-inflammatory M2-like patterns after stroke and a mild up-regulation of pro-inflammatory M1-like patterns at later stage. We also found that younger brains showed larger microglial response than middle aged brains. Moreover, beyond the standard M1/M2 dichotomy, a wide spectrum of novel microglial polarization states was activated in response to stroke, particularly the phenotypes related to Tlr2 and dietary fatty acids stimulation. We analyzed microglial gene expression change from 3 to 14 days after stroke onset and compared the activation pattern between 3-month and 12-month old brains.