Microglia have a more extensive and divergent response to interferon‐α compared with astrocytes

Abstract Type I interferons (IFN‐I) are crucial for effective antimicrobial defense in the central nervous system (CNS) but also can cause severe neurological disease (termed cerebral interferonopathy) as exemplified by Aicardi‐Goutières Syndrome. In the CNS, microglia and astrocytes have essential roles in host responses to infection and injury, with both cell types responding to IFN‐I. While the IFN‐I signaling pathways are the same in astrocytes and microglia, the extent to which the IFN‐I responses of these cells differ, if at all, is unknown. Here we determined the global transcriptional responses of astrocytes and microglia to the IFN‐I, IFN‐α. We found that under basal conditions, each cell type has a unique gene expression pattern reflective of its developmental origin and biological function. Following stimulation with IFN‐α, astrocytes and microglia also displayed a common core response that was characterized by the increased expression of genes required for pathogen detection and elimination. Compared with astrocytes, microglia had a more extensive and diverse response to IFN‐α with significantly more genes with expression upregulated (282 vs. 141) and downregulated (81 vs. 3). Further validation was documented for selected IFN‐I‐regulated genes in a murine model of cerebral interferonopathy. In all, the findings highlight not only overlapping but importantly divergent responses to IFN‐I by astrocytes versus microglia. This suggests specialized roles for these cells in host defense and in the development of cerebral interferonopathy.