Biology subjects

Ahlenius, H.

Publications and source records attributed to Ahlenius, H..

5 recordsLinked to original sources

bioRxiv2026

Isogenic forebrain organoids uncover early neurodevelopmental alterations and imbalances in neuronal function leading to hyperexcitation in Gaucher disease

Gaucher disease is a rare lysosomal storage disorder caused by autosomal recessive mutations in the GBA1 gene, encoding the lysosomal enzyme glucocerebrosidase. Gaucher disease is classified in 3 different subtypes depending on the presence and severity of neurological involvement, with type 2 resulting in fatal early-onset neuropathology and patients exhibiting developmental delays, seizures and early death. Studies investigating disease mechanisms of neuronopathic Gaucher disease are mainly based on animal models and focus predominantly on late neuronal phenotypes. Here, we established healthy control and Gaucher disease patient-derived iPSC lines and engineered them to obtain isogenic control and disease lines. Using these lines, we generated cortical and subpallial brain organoids in which we identified early-onset lipid dysregulation in form of glucosylceramide accumulation, highly elevated glucosylsphingosine, and a later increase in ganglioside levels, recapitulating clinical findings. Furthermore, single-cell transcriptomic profiling uncovered novel phenotypes in both cortical and subpallial forebrain organoids. Subpallial alterations consisted of an early increase in migrating interneurons in subpallial organoids, which upregulated cholesterol metabolism. Cortical alterations showed early upregulation of mitochondrial genes and a downregulation of proliferation, with a subsequent switch from GABAergic to glutamatergic neuron fate with a striking increase in gene expression related to the synaptic assembly. Functional assays demonstrated a marked hyperexcitability of cortical organoids and reduced response to GABA-A receptor blockage in Gaucher disease. Additional 2D neuronal network models confirmed the organoid data and showed that both glutamatergic and GABAergic neurons contribute to the phenotype, with hyperexcitability of Gaucher glutamatergic neurons and incapacity of Gaucher GABAergic neurons to balance the excessive excitation. This alteration represents a clinically significant phenotype as many patients exhibit an excitation/inhibition imbalance leading to treatment-resistant seizures, hastening their decline. In conclusion, our defined human models of Gaucher disease identify novel and clear phenotypes that can be used for drug screening or aid in development of new therapeutic strategies to ameliorate Gaucher disease.

neuroscience↗

bioRxiv2026

Galectin-3 drives tau-associated neuroinflammation, white matter degeneration and proteomic dysregulation

Tau pathology is a central driver of neurodegeneration, yet the molecular mechanisms linking tau accumulation to neuroinflammation, metabolic failure, and white matter degeneration remain incompletely understood. Galectin-3 (Gal3) is an inflammation-associated lectin expressed by activated microglia and has been implicated in neurodegenerative disease progression. Here, we investigated whether Gal3 modulates tau-driven pathology across cellular, molecular, and systems levels. Using the P301S tauopathy mouse model with genetic deletion of Gal3, we show that Gal3 loss robustly attenuates tau pathology across vulnerable brain regions, including cortex, hippocampus, and piriform-entorhinal cortex. Gal3 deletion reduced hyperphosphorylated and pathological tau species, normalized tau kinase signaling, and restored mitochondrial and vesicular trafficking pathways disrupted by tau accumulation. Proteomic and phosphoproteomic analyses revealed widespread normalization of tau-associated immune, metabolic, and trafficking pathways, with Tau-Gal3KO mice clustering closely with wild-type controls. In parallel, Gal3 deletion markedly reduced microglial activation and Gal3-positive inflammatory signatures, preserved white matter integrity, prevented axonal degeneration, and normalized oligodendrocyte and myelin abnormalities. Functionally, Gal3 deficiency enhanced microglial myelin phagocytosis and lysosomal degradation both in vitro and in vivo, suggesting improved clearance of myelin debris under inflammatory stress. Cell-type-specific analyses further revealed restoration of mitochondrial complex I subunit expression in both excitatory neurons and parvalbumin-positive interneurons. Importantly, translational studies in human iPSC-derived neurons demonstrated that extracellular Gal3 exacerbates tau hyperphosphorylation and aggregation following tau seeding, effects that were reversed by pharmacological Gal3 inhibition. Together, these findings identify Galectin-3 as a central upstream regulator linking tau pathology to neuroinflammation, proteomic dysregulation, mitochondrial dysfunction, and white matter degeneration. Targeting Gal3 represents a promising therapeutic strategy to mitigate tau-driven neurodegenerative processes.

neuroscience↗

bioRxiv2026

Ex vivo astrocyte-to-oligodendrocyte conversion in human adult cortical tissue using transcription factor overexpression

Multiple sclerosis (MS) is an autoimmune and neurological disorder characterized by myelin disruption and neuronal degeneration. Currently approved therapies focus on symptom relief but do not promote central nervous system (CNS) repair. In contrast, astrocytes proliferate and repopulate MS-related lesions. Moreover, in active lesions, they hinder regenerative processes such as neural progenitor migration. Here, we propose astrocytes as a potential target for myelin repair in the human diseased brain. To achieve this aim, we investigated whether glial fibrillary acidic protein (GFAP)+ astrocytes can be transdifferentiated into oligodendrocyte lineage cells through forced overexpression of transcription factors both in vitro and ex vivo organotypic cultures of human adult cortex. Our results show that overexpression of OLIG2 and SOX10 in human induced pluripotent stem cell-derived astrocytes gives rise to oligodendrocyte progenitor cells 12 days post-induction, as shown by morphological changes and O4 marker expression. Importantly, transdifferentiation of GFAP-expressing endogenous astrocytes in human adult cortical tissue give rise to mature oligodendrocytes, as shown by expression of CC1, after only 12 days of overexpression of OLIG2 and SOX10. To our knowledge, this is the first study to assess direct astrocyte-to-oligodendrocyte reprogramming in a human platform preserving the native three-dimensional architecture of the brain. Further work will be required to determine whether the reprogrammed cells can myelinate axons and to evaluate the potential of this approach for structural and functional repair in the demyelinated human CNS.

neuroscience↗

bioRxiv2025

Phenotypic Screening Identifies Flunarizine as an Inhibitor of Radiotherapy-Induced Astrocyte Reactivity with Therapeutic Potential in Glioblastoma

Radiotherapy is part of the standard-of-care for glioblastoma, yet tumors invariably recur as incurable lesions post-treatment. Recent studies suggest that radiation-induced astrocyte reactivity fosters a tumor-supportive environment, however effective strategies targeting reactive astrocyte phenotypes are lacking. Using a novel image-based assay, we screened over 1,700 small molecule compounds, identifying 29 that inhibit radiation-induced astrocyte reactivity in human astrocytes. Among these, Flunarizine, a calcium-entry blocker approved for migraine treatment, significantly reduced astrocyte reactivity in vitro and in vivo. In a genetically engineered glioblastoma mouse model, combining Flunarizine with radiotherapy markedly improved survival without affecting unirradiated controls, indicating specificity for a radiation-induced phenotype. Mechanistically, Flunarizine inhibited radiation-induced fibrosis in vivo and directly suppressed astrocytic TGF-beta activation in vitro. Notably, Flunarizine treatment had no direct effect on primary glioblastoma cells, emphasizing its microenvironmental specificity. In conclusion, we identified Flunarizine as a promising repurposed compound capable of effectively mitigating radiation-induced astrocyte reactivity and delaying glioblastoma recurrence. This approach offers a viable therapeutic strategy to enhance current glioblastoma treatments. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=195 SRC="FIGDIR/small/664538v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@d4d0d6org.highwire.dtl.DTLVardef@1dac551org.highwire.dtl.DTLVardef@1d071ccorg.highwire.dtl.DTLVardef@1df1a72_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2025

Rapid and efficient generation of human oligodendrocytes myelinating adult human cortical neurons

Intracerebral transplantation of stem cell-derived oligodendrocytes (OLs) is a promising strategy for repairing demyelinated human brain tissue, the main hallmark of white-matter disorders. However, several challenges hinder clinical translation, including slow or inefficient production of human OLs with current protocols, and difficulty in generating pure OL grafts capable of remyelinating injured neural circuits. Here, we present a robust, highly reproducible method for the rapid and efficient production of human OLs from human induced pluripotent stem cell derived long-term neuroepithelial-like stem (lt-NES) cells. Induced expression of the lineage-defining transcription factors SOX10 and OLIG2 in lt-NES cells is sufficient to generate a population of 80% OLs within 7 days. Importantly, these cells survive, differentiate and form functional OL-exclusive grafts when transplanted into adult human brain slices ex vivo, constituting the first demonstration that an OL-exclusive graft with robust myelination capacity can be generated in a clinically relevant allogeneic environment. This advance marks a significant step towards the clinical application of oligodendrocyte replacement therapy for human demyelinating disorders.

neuroscience↗