Project description:In response to central nervous system injury or disease, astrocytes become reactive, adopting context-dependent states with altered functions. Certain inflammatory insults induce reactive astrocyte states that lose homeostatic functions and gain neurotoxicity, and likely contribute to neuroinflammatory and neurodegenerative diseases. However, the cellular pathways controlling these states are not fully understood. Here, we combined single-cell transcriptomics with CRISPRi screening in human iPSC-derived astrocytes to systematically interrogate inflammatory reactivity. We found that autocrine-paracrine IL-6 and interferon signaling downstream of canonical NF-kB activation drove two distinct inflammatory reactive states dependent on STAT3 and IRF1, respectively. Furthermore, these states corresponded with those observed in other experimental contexts, including in vivo, and their markers were upregulated in the human brain in Alzheimer's disease and ischemic-hypoxic encephalopathy. These results and the platform we established have the potential to guide the development of therapeutics to selectively modulate different aspects of inflammatory astrocyte reactivity.
Project description:In response to central nervous system injury or disease, astrocytes become reactive, adopting context-dependent states with altered functions. Certain inflammatory insults induce reactive astrocyte states that lose homeostatic functions and gain neurotoxicity, and likely contribute to neuroinflammatory and neurodegenerative diseases. However, the cellular pathways controlling these states are not fully understood. Here, we combined single-cell transcriptomics with CRISPRi screening in human iPSC-derived astrocytes to systematically interrogate inflammatory reactivity. We found that autocrine-paracrine IL-6 and interferon signaling downstream of canonical NF-kB activation drove two distinct inflammatory reactive states dependent on STAT3 and IRF1, respectively. Furthermore, these states corresponded with those observed in other experimental contexts, including in vivo, and their markers were upregulated in the human brain in Alzheimer's disease and ischemic-hypoxic encephalopathy. These results and the platform we established have the potential to guide the development of therapeutics to selectively modulate different aspects of inflammatory astrocyte reactivity.
Project description:We assessed astrocyte diversity in the cortex, hippocampus, and striatum using sing cell RNA-seq (scRNA-seq). We also assessed cortical astrocytes in wild type control and transgenic APP/PS1dE9 mice using scRNA-seq.
Project description:Growing evidence implicates the importance of glia, particularly astrocytes, in neurological and psychiatric diseases. Here, we describe a rapid and robust method for the differentiation of highly pure populations of astrocytes from human induced pluripotent stem cells (hiPSCs), via a neural progenitor cell (NPC) intermediate. Using this method, we generated hiPSC-derived astrocyte populations (hiPSC-astrocytes) from 42 NPC lines (derived from 30 individuals) with an average of ~90% S100β-positive cells. Transcriptomic analysis demonstrated that the hiPSC-astrocytes are highly similar to primary human fetal astrocytes and characteristic of a non-reactive state. hiPSC-astrocytes respond to inflammatory stimulants, display phagocytic capacity and enhance microglial phagocytosis. hiPSC-astrocytes also possess spontaneous calcium transient activity. Our novel protocol is a reproducible, straightforward (single media) and rapid (<30 days) method to generate homogenous populations of hiPSC-astrocytes that can be used for neuron-astrocyte and microglia-astrocyte co-cultures for the study of neuropsychiatric disorders.