Glia最新文献

Amyotrophic lateral sclerosis (ALS) is a complex neurodegenerative disorder involving multiple cell types in the central nervous system. The key pathological features of ALS include the degeneration of motor neurons and the initiation and propagation of neuroinflammation mediated by nonneuronal cell types such as microglia. Currently, the specific mechanisms underlying the involvement of microglia in neuroinflammation in ALS are unclear. Consequently, we generated several human-induced pluripotent stem cell (iPSC) derived motor neuron and microglia cocultures. We utilized ALS patient-derived iPSCs carrying a common genetic variant, the hexanucleotide repeat expansion (HRE) in C9ORF72, as well as C9ORF72 knockout (KO) iPSC lines. iPSC-derived motor neurons and microglia demonstrated expression of cell type-specific markers and were functional. Phenotypic assessments on motor neurons and microglia in mono- and cocultures identified dysfunction in the expression and secretion of inflammatory cytokines and chemokines in lipopolysaccharide (LPS)-stimulated C9ORF72 HRE and C9ORF72 KO microglia. Analysis of single-cell RNA sequencing data from microglia and motor neuron cocultures revealed cell type-specific transcriptomic changes. Specifically, we detected the removal of an LPS-responsive microglia subpopulation, correlating with a dampened inflammatory response in C9ORF72 HRE and C9ORF72 KO microglia. Overall, our results support the critical role of microglia-mediated neuroinflammation in ALS pathology, and our iPSC-derived models should prove a valuable platform for further mechanistic studies of ALS-associated pathways.

THY1 is a cell surface protein of mature neurons. Although the Thy1 promoter is widely used as a neuron-specific promoter for transgenic expression, the role of the endogenous THY1 protein in the brain remains largely unknown. As THY1 receptors are expressed on astrocytes, THY1 may mediate signaling between both cell types. We therefore investigated the role of THY1 signaling in neuron-astrocyte communication using a full as well as a neuron-specific Thy1-knockout mouse model. Compared to wild-type mice, aged individuals of both strains exhibited an increased expression of a subset of astrocyte activation-associated genes, such as glial fibrillary acidic protein (Gfap), vimentin (Vim), and tenascin C (Tnc), whereas others appeared unaffected. Importantly, a cortical injury caused a permanent astrocytic activation in mice with neuronal Thy1 deletion, reflected by persistent high GFAP expression. The THY1-associated modulation of gene expression was confirmed in primary astrocytes cultured with or without recombinant THY1. Moreover, functional assays indicate that THY1 inhibits astrocyte proliferation while promoting apoptosis. Interaction of neuronal THY1 with ITGB1 on astrocytes was identified to be responsible for the THY1-mediated control of astrocyte activation. These data strongly suggest that THY1-bearing neurons keep astrocytes in a quiescent state. Consequently, a depletion of THY1 supports the development of a partially activated astrocyte phenotype characterized by increased expression of intermediate filaments, increased proliferative capacity, and reduced cell death. Our findings demonstrate that neuronal THY1 is a still unrecognized novel regulator in the communication between astrocytes and neurons involved in the maintenance and restoration of tissue homeostasis in the brain.

A large wave of myelination in the central nervous system (CNS) of mammals occurs during postnatal development, coinciding with the lactation period. High prolactin (PRL) levels are present in maternal milk; however, the role of milk PRL in lactating offspring remains under-investigated. This study explores whether PRL influences myelination during postnatal development in lactating and prepubertal mice. PRL and its receptors (PRLRs) are found in white matter (WM) tracts of lactating mice, but PRL mRNA is not expressed locally, supporting that the hormone derives from maternal milk, since the pituitary gland from neonatal mice does not secrete PRL. The absence of PRLRs (in PRLR knockout [KO] mice) results in a hypomyelinated phenotype characterized by a reduced corpus callosum volume, decreased myelin staining in WM tracts (cingulum, corpus callosum and dorsal fornix), lower myelin basic protein (MBP) expression levels, and a reduced number of oligodendroglial cells, as revealed by fewer OLIG2-positive cells in PRLR-KO nursing pups at postnatal day (PD) 12. The hypomyelination observed in PRLR-KO nursing pups continues into the prepubertal stage (PD28), when locomotor alterations (reduced distance traveled and decreased velocity of movements) manifest in PRLR-KO mice. These findings show that the lack of PRL signaling leads to brain hypomyelination in neonatal mice and negatively affects locomotor function at the prepubertal stage, thereby supporting the notion that PRL is required for adequate myelination during postnatal development.

The C9orf72 hexanucleotide repeat expansion mutation is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia, but its cell type-specific effects on energy metabolism and immune pathways remain poorly understood. Using induced pluripotent stem cell (iPSC)-derived motor neurons, astrocytes, and microglia from C9orf72 patients and their isogenic controls, we investigated metabolic changes at the single-cell level under basal and inflammatory conditions. Our results showed that microglia are particularly susceptible to metabolic disturbances. While C9orf72 motor neurons exhibited impaired mitochondrial respiration and reduced ATP production, C9orf72 microglia presented pronounced increases in glycolytic activity and oxidative stress, accompanied by the upregulation of the expression of key metabolic enzymes. These metabolic changes in microglia were exacerbated by inflammatory stimuli. To investigate how these changes affect the broader cellular environment, we developed a human iPSC-derived triculture system comprising motor neurons, astrocytes, and microglia. This model revealed increased metabolic activity in all cell types and highlighted that microglia-driven metabolic reprogramming in astrocytes contributes to the vulnerability of motor neurons under inflammatory conditions. Our findings highlight the central role of microglia in driving metabolic dysregulation and intercellular crosstalk in ALS pathogenesis and suggest that targeting metabolic pathways in immune cells may provide new therapeutic avenues.

Microglia are the resident immune cells of the CNS. Under homeostatic conditions, microglia play critical roles in orchestrating synaptic pruning, debris clearance, and dead cell removal. In disease, they are powerful mediators of neuroinflammation, as they rapidly respond to injury or infection within the CNS by altering their morphology, proliferating, and releasing cytokines and other signaling molecules. Understanding the molecular pathways involved in microglial function is pivotal for advancing neurobiological research and developing effective strategies for CNS disorders. In this context, P2RY12 is a G protein-coupled receptor (GPCR) that is uniquely enriched in microglia in the parenchyma and a canonical marker of homeostatic, ramified microglia. However, P2RY12 is downregulated in activated microglia and in neurological conditions. The consequences of P2RY12 downregulation in disease-associated microglia and how they influence microglial activation remain poorly understood. In this study, we apply transcriptional and histological methods to explore the changes to microglia upon a genetic P2RY12 loss. Our findings reveal that P2RY12-deficient microglia experience alterations in distinct metabolic pathways while preserving overall homeostatic microglial transcriptional identity. Lack of P2RY12 alters signature genes involved in homeostatic iron metabolism. Importantly, the genes encoding proteins in the Glutathione Peroxidase 4 (Gpx4)-Glutathione (GSH) antioxidant pathway related to ferroptosis susceptibility are impaired upon microglial activation with lipopolysaccharide (LPS) treatment. These results highlight the critical role of P2RY12 in regulating microglial immune and metabolic transcriptional responses under both homeostatic and inflammatory conditions, providing insights into its involvement in CNS pathophysiology.

During development and following injury-induced neurogenesis, olfactory ensheathing cells (OECs) envelope the axon bundles of sensory neurons and support their growth to the glomerular destinations in the olfactory bulb. Transplantation of OECs to various neuronal injury locations showed a reparative impact; however, there was huge variability. By combining mRNA sequencing with bioinformatics analysis and immunohistochemistry, we characterized the cellular and molecular biological properties of OECs of the lamina propria and their response to neuronal injury. We found that OECs do not express NGFR (p75) under steady state conditions, questioning the common approach of isolating OECs with NGFR antibodies. While OECs express a peculiar combination of markers of different types of glial cells, they are strikingly similar to satellite glia cells of the dorsal root ganglion; for example, they showed marked upregulation of genes involved in lipid metabolism during neuronal regeneration. Similar to satellite glia cells and unlike Schwann cells, adult OECs did not proliferate in response to injury. Like endothelial cells at the blood–brain barrier and unlike other glia types, OECs showed extensive connections via the tight junction protein Claudin 5. Furthermore, OECs lack water channels, which probably explains why they sustain a stable environment after olfactory epithelium ablation. Regulation of the extracellular osmolarity seems to involve Aquaporin 1 in perineural fibroblasts together with high levels of KCNJ10, Na⁺K⁺ATPase, and gap junctions in OECs. Optimizing the clinical uses of these unique glia cells is probably made easier by this thorough characterization of marker gene expression in steady state and during neurogenesis.

Glial cells are essential for nervous system development, homeostasis, and disease response, engaging in close interactions with neurons and other glial cells to carry out their functions. A large focus of glial studies has been on investigating how these cells work with neurons to execute their supportive roles, yet glial-glial interactions are even less well understood. Our previous work established that the loss of the secreted neurotrophin, Spätzle 3 (Spz3), from Drosophila cortex glia (CG) results in the morphological degradation of CG during mid to late larval development, where they lose their intricate interactions with neurons and other glial subtypes. Building on this work, we found that the loss of CG-neuron interactions triggers aberrant infiltration and functional compensation from all neighboring glial cell types—astrocytes, ensheathing glia (EG), and subperineurial glia (SPG)—and that both the CG disruption and surrounding aberrant glial extensions are inhibited by blocking CNS growth. These aberrant glial processes are able to compensate for at least one major CG function, the clearance of apoptotic neuronal corpses via Draper-mediated engulfment. Remarkably, even as astrocytes, EG, and SPG divert their cellular resources to extend into new territories and take on new functions, they continue to maintain their normal homeostatic roles such as synaptic remodeling (astrocytes), post-injury clearance of neurite debris (ensheathing glia), and regulation of the blood–brain barrier (SPG). These findings reveal that multiple glial subtypes can dynamically respond to nearby glial dysfunction to preserve CNS homeostasis, highlighting the resilience and adaptability of glia across subtypes.