Mikael Simons

https://rdp.sfb274.de/ (Research Data Platform) https://gepris.dfg.de/gepris/projekt/408885537 (DFG Gepris entry) The central nervous system (CNS) is a terminally differentiated tissue, where any insult carries a heightened risk - yet the tissue response to these insults is variable and can range from irreversible destruction to almost complete recovery. The rules that instruct these divergent outcomes are still unknown. The aim of this CRC is therefore to understand the biology of the multicellular ...

Since the first funding period, Z02 has provided comprehensive support for all our research projects, from experimental design to bioinformatics data analysis. We specialize in bulk and single-cell genomic methods, including technologies like 10x Genomics and flow-cytometry based isolation methods. Additionally, we offer training on tissue preparation, single-cell sorting, and the use of 10x Genomics equipment to ensure high-quality data. By centralizing sample preparation, sequencing, and analysis, ...

The cerebral cortex contains a special, perineuronally localized population of oligodendrocyte lineage cells with possible functions in connectivity and myelination. We hypothesize that this cell population serves as a reservoir of remyelinating cells after myelin damage. We will apply spatial transcriptome analysis with subcellular resolution in experimental models of demyelination and human tissue from patients with multiple sclerosis to define physiological and pathological states of perineuronal ...

Demyelinating injuries in the central nervous system trigger a regenerative process that relies on coordinated responses from multiple cell types, including the innate immune system. Here, we propose that a maladaptive chronic immune response may be initiated when microglia’s capacity to clear myelin debris is overwhelmed, leading to a self-propagating immune response that impairs remyelination and causes further tissue damage. We aim to identify the molecular checkpoints in microglia/macrophages ...

The incidence of Alzheimer’s disease (AD), the leading cause of dementia, increases rapidly with age, but why age constitutes the main risk factor is still poorly understood. Brain ageing affects oligodendrocytes and the structural integrity of myelin sheaths1, the latter of which is associated with secondary neuroinflammation2,3. As oligodendrocytes support axonal energy metabolism and neuronal health4,5,6,7, we hypothesized that loss of myelin integrity could be an upstream risk factor for ...

Compartmentalized inflammation is a key driver of multiple sclerosis (MS) progression, but the mechanisms sustaining its persistence remain unclear. A hallmark of this persistent and slowly evolving inflammatory process is chronic active MS lesions. We generated a high-resolution, single-cell molecular and spatial atlas of such lesions by combining single-nucleus RNA sequencing (snRNA-seq) with multiplexed error-robust fluorescence in situ hybridization (MERFISH). Within lesion rims, we identified ...

After demyelinating injury of the central nervous system, resolution of the mounting acute inflammation is crucial for the initiation of a regenerative response. Here, we aim to identify fatty acids and lipid mediators that govern the balance of inflammatory reactions within demyelinating lesions. Using lipidomics, we identify bioactive lipids in the resolution phase of inflammation with markedly elevated levels of n-3 polyunsaturated fatty acids. Using fat-1 transgenic mice, which convert n-6 ...

Remyelination requires innate immune system function, but how exactly microglia and macrophages clear myelin debris after injury and tailor a specific regenerative response is unclear. Here, we asked whether pro-inflammatory microglial/macrophage activation is required for this process. We established a novel toxin-based spinal cord model of de- and remyelination in zebrafish and showed that pro-inflammatory NF-κB–dependent activation in phagocytes occurs rapidly after myelin injury. We found ...

Understanding the complexity of cellular function within a tissue necessitates the combination of multiple phenotypic readouts. Here, we developed a method that links spatially-resolved gene expression of single cells with their ultrastructural morphology by integrating multiplexed error-robust fluorescence in situ hybridization (MERFISH) and large area volume electron microscopy (EM) on adjacent tissue sections. Using this method, we characterized in situ ultrastructural and transcriptional ...

Oligodendrocytes extend numerous cellular processes that wrap multiple times around axons to generate lipid-rich myelin sheaths. Myelin biogenesis requires an enormously productive biosynthetic machinery for generating and delivering these large amounts of newly synthesized lipids. Yet, a complete understanding of this process remains elusive. Utilizing volume electron microscopy, we demonstrate that the oligodendroglial endoplasmic reticulum (ER) is enriched in developing myelin, extending into ...

Age-related myelin damage induces inflammatory responses, yet its involvement in Alzheimer's disease remains uncertain, despite age being a major risk factor. Using a mouse model of Alzheimer's disease, we found that amyloidosis itself triggers age-related oligodendrocyte and myelin damage. Mechanistically, CD8+ T cells promote the progressive accumulation of abnormally interferon-activated microglia that display myelin-damaging activity. Thus, our data suggest that immune responses against ...

A hallmark of nervous system aging is a decline of white matter volume and function, but the underlying mechanisms leading to white matter pathology are unknown. In the present study, we found age-related alterations of oligodendrocyte cell state with a reduction in total oligodendrocyte density in aging murine white matter. Using single-cell RNA-sequencing, we identified interferon (IFN)-responsive oligodendrocytes, which localize in proximity to CD8(+) T cells in aging white matter. Absence of ...