Biology subjects

Kooistra, S. M.

Publications and source records attributed to Kooistra, S. M..

6 recordsLinked to original sources

bioRxiv2024

Identification of regional astrocyte heterogeneity associated with cuprizone-induced de- and remyelination using spatial transcriptomics

The cuprizone model is a well-characterized model to study processes of demyelination and remyelination, which are known features of multiple sclerosis. Cuprizone induces oligodendrocyte loss and severe demyelination in the brain, including the corpus callosum, hippocampus, and cortex. Loss of oligodendrocytes and myelin is accompanied by microgliosis and astrogliosis, wherein microglia and astrocytes partially lose their homeostatic functions and acquire a reactive/activated state. Cuprizone-induced demyelination peaks later in grey matter (GM) than in white matter (WM), and remyelination is more efficient in WM areas. Here, we aim to better understand regional diversity in microglia, astrocytes, and oligodendrocytes and their respective role in remyelination efficiency, by characterizing their response to cuprizone across brain regions. We applied spatial transcriptomics (ST) for unbiased gene activity profiling of multiple brain regions in a single tissue section, to identify region-associated changes in gene activity following cuprizone treatment. Gene activity changes were detected in highly abundant cell types, like neurons, oligodendrocytes, and astrocytes, but challenging to detect in low-abundant cell types such as microglia and oligodendrocyte precursor cells. ST revealed a significant increase in the expression of astrocyte markers Clu, Slc1a3, and Gfap during the demyelination phase in the WM fiber tract. In the cortex, the changes in GFAP expression were less prominent, both at the transcriptional and protein level. By mapping genes obtained from scRNAseq of FACS-sorted ACSA2-positive astrocytes onto the ST data, we observed astrocyte heterogeneity beyond the simple classification of WM- and GM-astrocytes in both control and cuprizone-treated mice. In the future, the characterization of these regional astrocyte populations could aid the development of novel strategies to halt the progression of demyelination and support remyelination. Highlights Astrocyte markers Clu, Slc1a3, and Gfap are increased in WM fiber tracts during demyelination Expression dynamics of astrogliosis markers Gfap and Vim during de-and remyelination depend on the brain region Combining scRNAseq with ST data revealed astrocyte heterogeneity beyond WM- and GM-differences scRNAseq-identified gene sets were differently affected by cuprizone treatment across brain regions

neuroscience↗

bioRxiv2023

IRF5 regulates microglial myelin clearance and cholesterol metabolism after demyelination

Interferon regulatory factor 5 (IRF5), a transcription factor highly involved in innate immunity that drives microglia/macrophage towards a pro-inflammatory state, has been associated to multiple sclerosis susceptibility but its role in MS pathogenesis is unknown. Here we analysed the role of IRF5 in multiple sclerosis animal models. Irf5-/- mice showed exacerbated damage in the chronic phase of experimental autoimmune encephalomyelitis (EAE) mice, despite an initial delay in its onset, as well as after lysolecithin injection into the spinal cord. Transcriptomic and lipidomic analysis evidence a role of this transcription factor in myelin metabolism and cholesterol homeostasis. Indeed, Irf5-/- mice showed an aberrant accumulation of myelin debris and lipidic structures, such as CE-containing lipid droplets and cholesterol crystals, suggesting that myelin-derived lipids are not properly processed. Cholesterol crystal accumulation leads to an aberrant inflammatory response, which block oligodendrocyte migration into the core of demyelinated lesion and remyelination. Pharmacologically facilitating cholesterol transport reduces lipid droplet accumulation and ameliorates EAE exacerbated damage in Irf5-/- mice. These results reveal for the first time the role of Irf5, a transcription factor necessary to orchestrate the immune responses, in phagocytes lipid metabolism which could be pivotal in regenerative responses such as remyelination.

neuroscience↗

bioRxiv2023

Radiotherapy induces persistent innate immune reprogramming of microglia into a primed state

More than half of all brain tumour survivors experience debilitating and often progressive cognitive decline after treatment with radiotherapy. Microglia, the resident macrophages in the brain, have been implicated in this decline. In response to various insults microglia can develop innate immune memory (IIM), which can either enhance (priming) or repress (tolerance) the response to subsequent inflammatory challenges. Here, we investigated whether radiation affects the IIM of microglia by irradiating the brains of rats and later exposing them to a secondary inflammatory stimulus. Comparative transcriptomic profiling and protein validation of microglia isolated from irradiated rats showed a stronger immune response to a secondary inflammatory insult demonstrating that radiation can lead to long-lasting molecular reprogramming of microglia. Transcriptomic analysis of post-mortem normal-appearing non-tumour brain tissue of glioblastoma patients indicates that radiation-induced microglial priming is conserved in humans. Targeting microglial priming after radiotherapy or avoiding further inflammatory insults could decrease radiotherapy-induced neurotoxicity.

neuroscience↗

bioRxiv2022

Early-life stress lastingly impacts microglial transcriptome and function under basal and immune-challenged conditions

Early-life stress (ELS) leads to increased vulnerability to psychiatric disorders including depression later in life. Neuroinflammatory processes have been implicated in ELS-induced negative health outcomes, but how ELS impacts microglia, the main tissue-resident macrophages of the central nervous system, is unknown. Here, we determined the effects of ELS induced by limited bedding and nesting material during the first week of life (postnatal days [P]2 - 9) on microglial i) morphology; ii) hippocampal gene expression; and iii) synaptosome phagocytic capacity in male pups (P9) and adult (P200) mice. The hippocampus of ELS-exposed adult mice displayed altered proportions of morphological subtypes of microglia, as well as microglial transcriptomic changes related to the tumor necrosis factor response and protein ubiquitination. ELS exposure leads to distinct gene expression profiles during microglial development from P9 to P200 and in response to an LPS challenge at P200. Functionally, synaptosomes from ELS-exposed mice were phagocytosed less by age-matched microglia. At P200, but not P9, ELS microglia showed reduced synaptosome phagocytic capacity when compared to CTRL microglia. Lastly, we confirmed the ELS-induced increased expression of the phagocytosis-related gene GAS6 that we observed in mice, in the dentate gyrus of individuals with a history of child abuse using in situ hybridization. These findings reveal persistent effects of ELS on microglial function and suggest that altered microglial phagocytic capacity is a key contributor to ELS-induced phenotypes.

neuroscience↗

bioRxiv2021

Epigenetic regulation of innate immune memory in microglia

Microglia are the tissue-resident macrophages of the CNS. They originate in the yolk sac, colonize the CNS during embryonic development and form a self-sustaining population with limited turnover. A consequence of their relative slow turnover is that microglia can serve as a long-term memory for inflammatory or neurodegenerative events. We characterized the epigenomes and transcriptomes of microglia exposed to different stimuli; an endotoxin challenge (LPS) and genotoxic stress (DNA repair deficiency-induced accelerated aging). Whereas the enrichment of permissive epigenetic marks at enhancer regions explains training (hyperresponsiveness) of primed microglia to LPS challenge, the tolerized response of microglia seems to be regulated by loss of permissive epigenetic marks. Here, we identify that inflammatory stimuli and accelerated aging because of genotoxic stress activate distinct gene networks. These gene networks and associated biological processes are partially overlapping, which is likely driven by specific transcription factor networks, resulting in altered epigenetic signatures and distinct functional (desensitized vs. primed) microglia phenotypes.

neuroscience↗

bioRxiv2020

Profiling microglia from AD donors and non-demented elderly in acute human post-mortem cortical tissue

Microglia are the tissue-resident macrophages of the central nervous system (CNS). Recent studies based on bulk and single-cell RNA sequencing in mice indicate high relevance of microglia with respect to risk genes and neuro-inflammation in Alzheimers disease. Here, we investigated microglia transcriptomes at bulk and single cell level in non-demented elderly and AD donors using acute human post-mortem cortical brain samples. We identified 9 human microglial subpopulations with heterogeneity in gene expression. Notably, gene expression profiles and subcluster composition of microglia did not differ between AD donors and non-demented elderly in bulk RNA sequencing nor in single-cell sequencing.

neuroscience↗