Isolation of glia from Alzheimer's mice reveals inflammation and dysfunction

Reactive astrocytes and microglia are associated with amyloid plaques in Alzheimer's disease (AD). Yet, not much is known about the molecular alterations underlying this reactive phenotype. To get an insight into the molecular changes underlying AD induced astrocyte and microglia reactivity, we performed a transcriptional analysis on acutely isolated astrocytes and microglia from the cortex of aged controls and APPswe/PS1dE9 AD mice. As expected, both cell types acquired a proinflammatory phenotype, which confirms the validity of our approach. Interestingly, we observed that the immune alteration in astrocytes was relatively more pronounced than in microglia. Concurrently, our data reveal that astrocytes display a reduced expression of neuronal support genes and genes involved in neuronal communication. The microglia showed a reduced expression of phagocytosis and/or endocytosis genes. Co-expression analysis of a human AD expression data set and the astrocyte and microglia data sets revealed that the inflammatory changes in astrocytes were remarkably comparable in mouse and human AD, whereas the microglia changes showed less similarity. Based on these findings we argue that chronically proinflammatory astrocyte and microglia phenotypes, showing a reduction of genes involved in neuronal support and neuronal signaling, are likely to contribute to the neuronal dysfunction and cognitive decline in AD.