Mikael Simons

The bone marrow in the skull is important for shaping immune responses in the brain and meninges, but its molecular makeup among bones and relevance in human diseases remain unclear. Here, we show that the mouse skull has the most distinct transcriptomic profile compared with other bones in states of health and injury, characterized by a late-stage neutrophil phenotype. In humans, proteome analysis reveals that the skull marrow is the most distinct, with differentially expressed neutrophil-related ...

The bone marrow in the skull is important for shaping immune responses in the brain and meninges, but its molecular makeup among bones and relevance in human diseases remain unclear. Here, we show that the mouse skull has the most distinct transcriptomic profile compared with other bones in states of health and injury, characterized by a late-stage neutrophil phenotype. In humans, proteome analysis reveals that the skull marrow is the most distinct, with differentially expressed neutrophil-related ...

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 ...

Progranulin (PGRN) haploinsufficiency is a major risk factor for frontotemporal lobar degeneration with TAR DNA-binding protein 43 (TDP-43) pathology (FTLD-GRN). Multiple therapeutic strategies are in clinical development to restore PGRN in the CNS, including gene therapy. However, a limitation of current gene therapy approaches aimed to alleviate FTLD-associated pathologies may be their inefficient brain exposure and biodistribution. We therefore developed an adeno-associated virus (AAV) targeting ...

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 ...

Corpus callosum dissections were lysed in 300 µL STET lysis buffer (1% (v/v) Triton X-100, 150 mM NaCl, 2 mM EDTA, 50 mM TrisHCl pH 7.5) with a Precellys Evolution homogenizer (Bertin, Germany) using 0.5 mL soft tissue homogenization kit CK14 applying two cycles of 30 s with a speed of 6500rpm. After 15 min incubation on ice, samples were centrifuged at 16,000×g for 15 min to remove undissolved material and cell debris. The supernatant was transferred to a fresh protein lobind tube (Eppendorf, ...

Secretome analysis of primary neuronal cultures was performed using the high-performance secretome protein enrichment with click sugars" (hiSPECS) method, described in detail previously (Tüshaus et al, 2020). In brief, neurons were cultured for 48 h (DIV 5-7) in the presence of 50 µM ManNAz (#88904, ThermoFisher), cultivation media was filtered through 0.45 µm spin columns (Sigma-Aldrich, CLS8163). Glycoproteins were enriched using ConA agarose beads (Sigma, C7555) and clicked to magnetic DBCO ...

Primary microglia were isolated from mouse brains (cerebrum) using MACS Technology (Miltenyi Biotec) according to manufacturer´s instructions and as previously described (Daria et al., 2017). Briefly, brain cerebrum was dissected, freed from meninges and dissociated by enzymatic digestion using a Neural Tissue Dissociation Kit P (Miltenyi Biotec) and subsequent mechanical dissociation using 3 fire-polished glass Pasteur pipettes of decreasing diameter. CD11b positive microglia were magnetically ...

After washing the primary cells with 1x PBS, cell-type specific growth media containing serum supplements with 50 µM of ManNAz (Thermo) was added for 48h. Afterwards, conditioned media was collected and filtered through Spin-X 0.45 µM cellulose acetate centrifuge tube filter (#8163, Costar) and stored at -20°C in protein Lobind tubes until further usage. Glycoprotein enrichment was performed using 60 µL Concanavalin A (ConA) bead slurry per sample (Sigma). ConA beads were washed twice with 1 mL ...

Microglia isolated by MACS from WT and Myd88-/- mouse pups were seeded at a density of 1×106 cells per 60-mm dish in DMEM/FCS/L929 medium. After 2 DIV, microglia were washed with warm DMEM/pyruvate medium and treated with 20 µg/mL myelin debris (or HEPES control) in 2 mL of TIC medium for 4 h. After treatment, the cells were washed with DMEM/pyruvate medium, and incubated with 4 mL of DMEM containing 0.2% BSA for 16 h. The cells in each dish were washed with 2 mL of cold PBS on ice, and lysed ...

Grey and white matter (corpus callosum) were dissected from the brain of 4 months and 21 months old wild type mice, single cell suspension was isolated using Neural Tissue Dissection kit (myelin was removed on percoll gradient) then microglia cells were isolated using CD11b microbeads by Magnetic separation with MS columns (MACS technology).The cell pellets are resuspended in the RLT buffer (100ul-150ul), snap frozen in liquid nitrogen and stored in -80 freezer. RNA was extracted and transcriptome ...

Remyelination can occur naturally in demyelinating lesions, but often fails in human demyelinating diseases such as multiple sclerosis (MS). The function of the innate immune system is essential for the regenerative response, 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 ...

To understand how cells communicate with each other, it is essential to define the cellular secretome, a collection of proteins including soluble secreted, unconventionally secreted and proteolytically-shed proteins. Quantitative methodologies to decipher the secretome are challenging, due to the requirement of large cell numbers and abundant serum proteins that interfere with the detection of low-abundant cellular secretome proteins. Here, we have use the highe perfomance ...

To understand how cells communicate with each other, it is essential to define the cellular secretome, a collection of proteins including soluble secreted, unconventionally secreted and proteolytically-shed proteins. Quantitative methodologies to decipher the secretome are challenging, due to the requirement of large cell numbers and abundant serum proteins that interfere with the detection of low-abundant cellular secretome proteins. Here, we miniaturized secretome analysis by developing the ...

Niemann-Pick type C disease is a rare neurodegenerative disorder mainly caused by mutations in Npc1, resulting in abnormal late endosomal/lysosomal lipid storage. Although microgliosis is a prominent pathological feature, direct consequences of NPC1 loss on microglial function remain uncharacterized. Previously, we have characterized microglial proteome alterations in the NPC1 KO mouse model (PXD019447). In order to investigate similar changes in humans, we have cultured monocyte derived macrophages ...