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CLEC16A in astrocytes promotes mitophagy and limits pathology in a multiple sclerosis mouse model [bulk RNA-Seq]

ABSTRACT: Astrocytes promote neuroinflammation and neurodegeneration in multiple sclerosis (MS) through cell-intrinsic activities and their ability to recruit and activate other cell types. Here, in a genome-wide CRISPR-based forward genetic screen investigating regulators of astrocyte proinflammatory responses, we identified the C-type lectin domain-containing 16A gene (CLEC16A), linked to MS susceptibility, as a suppressor of nuclear factor-κB (NF-κB) signaling. Gene and small-molecule perturbation studies in mouse primary and human embryonic stem cell-derived astrocytes in combination with mitochodrial, metabolic and multiomic analyses established that CLEC16A promotes mitophagy, limiting mitochondrial dysfunction and the accumulation of mitochondrial products that activate NF-κB, the NLRP3 inflammasome and gasdermin D. Astrocyte-specific Clec16a inactivation increased NF-κB, NLRP3 and gasdermin D activation in vivo, worsening experimental autoimmune encephalomyelitis, a mouse model of MS. Moreover, we detected disrupted mitophagic capacity and gasdermin D activation in astrocytes in samples from individuals with MS. These findings identify CLEC16A as a suppressor of astrocyte pathological responses and a candidate therapeutic target in MS. Scheduled for publication in Nature Neuroscience DOI: 10.1038/s41593-025-01875-9

ORGANISM(S): Mus musculus Homo sapiens

PROVIDER: GSE189030 | GEO | 2023/11/09

REPOSITORIES: GEO

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Project description:Astrocytes are instrumental in both maintaining CNS homeostasis and responding to tissue injury. While astrocyte activation may be a beneficial response to acute pathologies, prolonged reactive gliosis is thought to be injurious in neurodegenerative diseases, including multiple sclerosis (MS). A major limitation of studying neurodegenerative diseases is lack of human pathological specimens obtained during the acute stages, thereby relegating research to post mortem specimens often obtained years after the initiation of pathology. Rodent reactive astrocytes have been shown to be cytotoxic to neurons and oligodendrocytes but may differ from human cells, especially in diseases with known genetic susceptibility. Herein, we purified human CD49f+ astrocytes from differentiated induced pluripotent stem cells derived from individual patient and control peripheral white blood cell samples. We compared TNF and IL1a stimulated human reactive astrocytes from 7 persons with MS and 6 non-MS controls and show their specific astrocyte transcriptomic profiles are remarkably similar to those described in rodents. The functional effect of astrocyte conditioned media (ACM) was examined in a human oligodendrocyte precursor cell (OPC) line differentiation assay using a transgenic secreted reporter of myelin basic protein (MBP) expression. ACM was not cytotoxic to the OPCs but robustly inhibited the MBP reporter. No differences were seen between MS and control stimulated astrocytes at either the transcript level or in functional OPC suppression assays. We next used RNAseq to interrogate differentially expressed genes in the OPC lines that had suppressed differentiation from the human ACM. Remarkably, not only was OPC differentiation and myelin gene expression suppressed, but we observed induction of several immune pathways and Nf-κB signaling in OPCs exposed to the ACM. These data support the notion that reactive astrocytes can inhibit OPC differentiation thereby limiting their remyelination capacity, and that OPCs take on an immune profile in the context of inflammatory cues.

Project description:BACKGROUND: Cryopyrin-Associated Periodic Syndrome (CAPS) is an autoinflammatory condition consequence of monoallelic variants in the NLRP3 gene that exacerbate IL-1β production. These variants are gain-of-function, but the exact regulatory mechanism of the NLRP3 CAPS-inflammasome is not well yet understood. It is considered as a hypersensitive inflammasome triggered by cell priming, but patients with CAPS and animal disease models present inflammatory flares in the absence of external triggers.OBJECTIVES: To study the regulation and activation of the NLRP3 inflammasome in CAPS.METHODS: CAPS derived blood samples and genetically modified macrophages expressing different NLRP3 CAPS-associated variants were used to assess NLRP3 function dissociated from cell priming and cell metabolism.RESULTS: We found that CAPS-associated variants constitutively result in active NLRP3 inflammasomes, that induce a basal cleavage of gasdermin D, IL-18 release and pyroptosis. The constitutive active NLRP3 inflammasome was blocked by MCC950 and was dependent on NLRP3 expression level, being further regulated by deubiquitination. We also showed that activation of NF-κB with lipopolysaccharide or other endogenous host-derived molecules (palmitate, S100A9 or IL-6) further modulated the activation of the NLRP3 CAPS inflammasome and expanded the repertoire of molecules secreted from CAPS macrophages to IL-1β, IL-1α, HMGB1, cystatin B and the P2X7 receptor, identifying novel proteins involved in CAPS pathogenesis. NLRP3 inflammasomes with CAPS associated variants affected the immunometabolism of the myeloid compartment and impaired glycolysis.CONCLUSIONS: These findings demonstrate that NLRP3 CAPS-associated variants form a constitutive active inflammasome that induce basal pyroptosis and IL-18 release without cell priming, suggesting a priming-independent mechanism for the initiation of CAPS flares characterized with a profound affection in the immunometabolism.

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CLEC16A in astrocytes promotes mitophagy and limits pathology in a multiple sclerosis mouse model [bulk RNA-Seq]

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