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:Non-neuronal cells, including astrocytes, play a crucial role in the selective motor neuron pathology in amyotrophic lateral sclerosis (ALS). How astrocytes exactly contribute to the disease is not fully elucidated. Therefore, we characterised human induced pluripotent stem cell (hiPSC)-derived astrocytes from FUS-ALS patients, and incorporated these astrocytes into a human motor unit model to investigate the astrocytic effect on hiPSC-derived motor neuron network and neuromuscular junctions (NMJs). We observed a dysregulation of astrocyte homeostasis, which resulted in a FUS-ALS-mediated increase in reactivity and secretion of pro-inflammatory cytokines. Upon coculture with motor neurons and myotubes, we detected a cytotoxic effect on motor neuron-neurite morphology and outgrowth, as well as on NMJ formation and functionality, which was improved or fully rescued by isogenic control astrocytes. We conclude that mutant astrocytes have both a gain-of-toxicity and loss-of-support function in ALS, ultimately contributing to the disruption of motor neuron homeostasis, intercellular networks and NMJs.
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.
Project description:Schizophrenia is a complex and severe neuropsychiatric disorder, with a wide range of debilitating symptoms. Several aspects of its multifactorial complexity are still unknown, and some are accepted to be an early developmental deficiency with a more specifically neurodevelopmental origin. ??Molecular and functional abnormalities in astrocytes play a role in the etiology and pathogenesis of schizophrenia. In this study, human induced pluripotent stem cells (hiPSC)-derived astrocytes from schizophrenia patients were investigated regarding their proteome, inflammatory responses, and their secretome effect on vascularization. Proteomic analysis revealed alterations in proteins related to immune function and vascularization. Taken together, our results suggest that schizophrenia astrocytes are immunologically dysfunctional which might affect vascularization through secreted factors.
Project description:Schizophrenia is a complex and severe neuropsychiatric disorder, with a wide range of debilitating symptoms. Several aspects of its multifactorial complexity are still unknown, and some are accepted to be an early developmental deficiency with a more specifically neurodevelopmental origin. ??Molecular and functional abnormalities in astrocytes play a role in the etiology and pathogenesis of schizophrenia. In this study, human induced pluripotent stem cells (hiPSC)-derived astrocytes from schizophrenia patients were investigated regarding their proteome, inflammatory responses, and their secretome effect on vascularization. Proteomic analysis revealed alterations in proteins related to immune function and vascularization. Taken together, our results suggest that schizophrenia astrocytes are immunologically dysfunctional which might affect vascularization through secreted factors.