Biology subjects

Antel, J.

Publications and source records attributed to Antel, J..

10 recordsLinked to original sources

bioRxiv2025

Detection of astrocyte epigenetic memory in in vitro systems, experimental autoimmune encephalomyelitis and multiple sclerosis samples

We recently described astrocyte pro-inflammatory epigenetic memory based on multiple complementary in vivo and in vitro studies, and the analysis of multiple sclerosis samples. Based on bioinformatic analyses, ODea and Liddelow argued that the astrocyte epigenetic memory we described is the result of contamination with immune cells, particularly myeloid cells. We rebut ODea and Liddelow arguments as follows: (1) We show substantial purity of astrocytes analyzed in in vivo and in vitro systems; (2) We recapitulate astrocyte memory responses using five independent pure astrocyte in vitro systems, and show its dependency on the histone acetyl transferase p300; and (3) Using the Liddelow lab bioinformatic pipeline to implement purity and cell-quality criteria, we detect astrocyte epigenetic memory in five independent scRNA-seq experimental autoimmune encephalomyelitis (EAE) and multiple sclerosis (MS) astrocyte datasets. These additional analyses and studies provide further support for the existence of astrocyte pro-inflammatory epigenetic memory.

neuroscience↗

bioRxiv2024

Single Cell RNAseq to identify subpopulations of glial progenitors in iPSC-derived oligodendroglial lineage cultures

Cellular heterogeneity is a common issue in differentiation protocols of oligodendrocytes (OLs) from human induced pluripotent stem cells. Our previous work described a novel method to generate OLs and highlighted the presence of glial progenitors. Here, we unravel the glial heterogeneity and characterize the response of isolated subpopulations to differentiation. This study provides a novel tool for studying the dynamics of glial development in vitro and on a transcriptomic level.

neuroscience↗

bioRxiv2024

Pro-Inflammatory Molecules Implicated in Multiple Sclerosis Divert the Development of Human Oligodendrocyte Lineage Cells

Background and ObjectivesOligodendrocytes (OL) and their myelin-forming processes are targeted and lost during the disease course of Multiple Sclerosis (MS), targeted by infiltrating leukocytes and their effector cytokines. Myelin repair is considered to be dependent on recruitment and differentiation of oligodendrocyte precursor cells (OPCs). The basis of failure of re-myelination during the disease course of MS remains to be defined. The aim of this study is to determine the impact of pro-inflammatory molecules tumor necrosis factor (TNF) and interferon gamma (IFN{gamma}) on the differentiation of human OPCs. MethodsWe generated human OPCs from induced pluripotent stem cells with a reporter gene under the OL-specific transcription factor SOX10. We treated the cells in vitro with TNF or IFN{gamma} and evaluated effects in terms of cell viability, expression of OL-lineage markers, and co- expression of astrocyte markers. To relate our findings to the molecular properties of OPCs as found in the MS brain we re-analyzed publicly available single nuclear RNAseq datasets. ResultsOur analysis indicated that both TNF and IFN{gamma} decreased the proportion of cells differentiating into the OL-lineage; consistent with previous reports. We now observe the TNF effect is linked to aberrant OPC differentiation. A subset of O4+, reporter-positive cells co- expressed the astrocytic marker Aquaporin-4 (AQP4). On the transcriptomic level, the cells acquire an astrocyte-like signature alongside a conserved reactive phenotype. Analysis of single- nuclear RNAseq datasets from human MS brain revealed a subset of OPCs expressing an astrocytic signature. DiscussionIn the context of MS, these results imply that OPCs are present but inhibited from differentiating along the OL-lineage, with a subset acquiring a reactive and stem-cell like phenotype, reducing their capacity to contribute towards repair. These findings help define a potential basis for the impaired myelin repair in MS and provide a prospective route for regenerative treatment.

neuroscience↗

bioRxiv2024

Uncovering immune characteristics of neurons in the context of multiple sclerosis and experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is an immune-mediated disease characterized by chronic inflammation and damage to the central nervous system, and substantial characterization of molecular signatures of glial and immune cells in the disease has been conducted. However, comparatively less well characterized is the molecular signature of pathologically inflamed neurons. Here, we accessed multi-omic high-throughput transcriptomic and epigenomic data to investigate the molecular signature of neurons from progressive MS patients and from mice subjected to experimental autoimmune encephalomyelitis (EAE). Our results indicate a shared and consistent neuronal gene expression signature in MS and EAE samples including a notable upregulation of immune system related genes and processes. Analysis of immune-enriched pathways in retinal ganglion cells (RGCs) and motor neurons from mice subjected to EAE revealed enrichment for the major histocompatibility complex class I pathway and interferon response genes in both types of neurons, and ATAC-seq analysis confirmed the accessibility of these genes. Parallel analyses of neurons from MS patients identified a signature of 48 commonly upregulated immune genes in neurons. Prediction of transcriptional regulators of these genes identified key upstream regulators including signal transducer and activation of transcription 1 (STAT1) and interferon response factor 5 (IRF5), highly involved in immune-related processes, with significant gene expression changes in both RGCs and motor neurons. Protein-protein interaction analyses among the transcriptional regulators unveiled intricate interactions among transcription factors, especially from the IRF and STAT families, suggesting their importance in regulating immune gene expression in inflamed neurons. Small molecule inhibition of IRF5 in inflamed neurons in vitro promoted cell survival and reduced the expression of the immune gene signature, supporting the biological relevance of IRF5 in mediating the neuronal inflammatory response. Together, this study identifies regulated immune processes in neurons from EAE mice and from MS patient samples suggesting potential roles for neuronal immune molecules in disease progression, as revealed by transcriptomic, epigenomic, and experimental approaches. Further, the results strongly implicate active interferon signaling in neurons driving immune related changes in gene expression through IRF5 and STAT1 transcription factor activity, potentially impacting downstream neuronal survival through IRF5 activity.

neuroscience↗

bioRxiv2024

Disease-associated astrocyte epigenetic memory promotes CNS pathology

Astrocytes play important roles in the central nervous system (CNS) physiology and pathology. Indeed, astrocyte subsets defined by specific transcriptional activation states contribute to the pathology of neurologic diseases, including multiple sclerosis (MS) and its pre-clinical model experimental autoimmune encephalomyelitis (EAE)1-8. However, little is known about the stability of these disease-associated astrocyte subsets, their regulation, and whether they integrate past stimulation events to respond to subsequent challenges. Here, we describe the identification of an epigenetically controlled memory astrocyte subset which exhibits exacerbated pro-inflammatory responses upon re-challenge. Specifically, using a combination of single-cell RNA sequencing (scRNA-seq), assay for transposase-accessible chromatin with sequencing (ATAC-seq), chromatin immunoprecipitation with sequencing (ChIP-seq), focused interrogation of cells by nucleic acid detection and sequencing (FIND-seq), and cell-specific in vivo CRISPR/Cas9-based genetic perturbation studies we established that astrocyte memory is controlled by the metabolic enzyme ATP citrate lyase (ACLY), which produces acetyl coenzyme A (acetyl-CoA) used by the histone acetyltransferase p300 to control chromatin accessibility. ACLY+p300+ memory astrocytes are increased in acute and chronic EAE models; the genetic targeting of ACLY+ p300+ astrocytes using CRISPR/Cas9 ameliorated EAE. We also detected responses consistent with a pro-inflammatory memory phenotype in human astrocytes in vitro; scRNA-seq and immunohistochemistry studies detected increased ACLY+ p300+ astrocytes in chronic MS lesions. In summary, these studies define an epigenetically controlled memory astrocyte subset that promotes CNS pathology in EAE and, potentially, MS. These findings may guide novel therapeutic approaches for MS and other neurologic diseases.

immunology↗

bioRxiv2023

Identity and Nature of Neural Stem Cells in the Adult Human Subventricular Zone

The existence of neural stem cells (NSCs) in adult human brain neurogenic regions remains unresolved. To address this, we created a cell atlas of the adult human subventricular zone (SVZ) derived from fresh neurosurgical samples using single-cell transcriptomics. We discovered 2 adult radial glia (RG)-like populations, aRG1 and aRG2. aRG1 shared features with fetal early RG (eRG) and aRG2 were transcriptomically similar to fetal outer RG (oRG). We also captured early neuronal and oligodendrocytic NSC states. We found that the biological programs driven by their transcriptomes support their roles as early-lineage NSCs. Finally, we show that these NSCs have the potential to transition between states and along lineage trajectories. These data reveal that multipotent NSCs reside in the adult human SVZ.

neuroscience↗

bioRxiv2022

Translocator protein is a marker of activated microglia in rodent models but not human neurodegenerative diseases

Microglial activation plays central roles in neuro-inflammatory and neurodegenerative diseases. Positron emission tomography (PET) targeting 18kDa Translocator Protein (TSPO) is widely used for localising inflammation in vivo, but its quantitative interpretation remains uncertain. We show that TSPO expression increases in activated microglia in mouse brain disease models but does not change in a non-human primate disease model or in common neurodegenerative and neuroinflammatory human diseases. We describe genetic divergence in the TSPO gene promoter, consistent with the hypothesis that the increase in TSPO expression in activated myeloid cells is unique to a subset of species within the Muroidea superfamily of rodents. We show that TSPO is mechanistically linked to classical pro-inflammatory myeloid cell function in rodents but not humans. These data emphasise that TSPO expression in human myeloid cells is related to different phenomena than in mice, and that TSPO PET reflects density of inflammatory cells rather than activation state.

neuroscience↗

bioRxiv2020

Vitamin D regulates MerTK-dependent phagocytosis in human myeloid cells

Vitamin D deficiency is a major environmental risk factor for the development of multiple sclerosis (MS). The major circulating metabolite of vitamin D (25OHD) is converted to the active form (calcitriol) by the hydroxylase enzyme CYP27B1. In MS lesions the tyrosine kinase MerTK expressed by microglia and macrophages regulates phagocytosis of myelin debris and apoptotic cells that can accumulate and inhibit tissue repair and remyelination. We show that calcitriol downregulates MerTK mRNA and protein expression in adult human microglia and monocyte-derived macrophages, thereby inhibiting myelin phagocytosis and apoptotic cell clearance. Proinflammatory myeloid cells express high levels of CYP27B1 compared to homeostatic (TGF{beta}-treated) myeloid cells. Only proinflammatory cells in the presence of TNF- generate calcitriol from 25OHD, resulting in repression of MerTK expression and function. The selective production of calcitriol in proinflammatory myeloid cells leading to downregulation of MerTK-mediated phagocytosis has the potential to reduce the risk for auto-antigen presentation while retaining the phagocytic ability of homeostatic myeloid cells, thereby contributing to inflammation reduction and enhanced tissue repair.

immunology↗

bioRxiv2018

Single-cell RNA-seq reveals that glioblastoma recapitulates normal brain development

SummaryCancer stem cells are critical for cancer initiation, development, and resistance to treatments. Our understanding of these processes, and how they relate to glioblastoma heterogeneity, is limited. To overcome these limitations, we performed single-cell RNA-sequencing on 38 296 glioblastoma cells and 22 637 normal human fetal brain cells. Using an unbiased approach, we mapped the lineage hierarchy of the developing human brain and compared the transcriptome of each cancer cell to this roadmap. We discovered a conserved neural trilineage cancer hierarchy with glial progenitor-like cells at the apex. We also found that this progenitor population contains the majority of cancers cycling cells and is the origin of heterogeneity. Finally, we show that this hierarchal map can be used to identify therapeutic targets specific to progenitor cancer stem cells. Our analyses show that normal brain development reconciles glioblastoma development, unravels the origin of glioblastoma heterogeneity, and helps to identify cancer stem cell-specific targets.

cancer biology↗

bioRxiv2017

α7 nicotinic acetylcholine receptor signalling modulates the inflammatory and iron homeostasis in fetal brain microglia

Neuroinflammation in utero may result in life-long neurological disabilities. Microglia play a pivotal role, but the mechanisms are poorly understood. No early postnatal treatment strategies exist to enhance neuroprotective potential of microglia. We hypothesized that agonism on 7 nicotinic acetylcholine receptor (7nAChR) in fetal microglia will augment their neuroprotective transcriptome profile, while the antagonistic stimulation of 7nAChR will achieve the opposite. Using an in vivo - in vitro model of developmental programming of neuroinflammation induced by lipopolysaccharide (LPS), we validated this hypothesis in primary fetal sheep microglia cultures re-exposed to LPS in presence of a selective 7nAChR agonist or antagonist. Our RNAseq and protein level findings show that a pro-inflammatory microglial phenotype acquired in vitro by LPS stimulation is reversed with 7nAChR agonistic stimulation. Conversely, antagonistic 7nAChR stimulation potentiates the pro-inflammatory microglial phenotype. Surprisingly, under conditions of LPS double-hit an interference of a postulated 7nAChR - ferroportin signaling pathway may impede this mechanism. These results suggest a therapeutic potential of 7nAChR agonists in early re-programming of microglia in neonates exposed to in utero inflammation via an endogenous cerebral cholinergic anti-inflammatory pathway. Future studies will assess the role of interactions between inflammation-triggered microglial iron sequestering and 7nAChR signaling in neurodevelopment.

neuroscience↗