Transcriptome of Irradiated Microglia

Whole brain irradiation remains important in the management of brain tumors. Although necessary for improving survival outcomes, cranial irradiation also results in cognitive decline in long-term survivors. A chronic inflammatory state characterized by microglial activation has been implicated in radiation-induced brain injury, and here we present a comprehensive transcriptional profile of irradiated microglia. Fluorescence-activated cell sorting (FACS) was used to isolate CD11b+ microglia from the hippocampi of C57BL/6 and Balb/c mice 1 month after 10Gy cranial irradiation. Affymetrix gene expression profiles were evaluated using linear modeling and rank product analyses. A conserved signature of irradiation was identified across strains, and gene set enrichment analysis was employed to functionally compare our signature to publically available mouse and human datasets. FACS-sorted microglia samples from three mice were analyzed from each of four groups: sham irradiated C57BL/6 mice, 10 Gy irradiated C57BL/6 mice, sham irradiated Balb/c mice, 10 Gy irradiated Balb/c mice (12 total samples analyzed). All mice were analyzed 1 month after sham or 10 Gy irradiation.