Biology subjects

Stefanova, N.

Publications and source records attributed to Stefanova, N..

8 recordsLinked to original sources

bioRxiv2026

Oligodendrocytes may provide the extra density of α-synuclein filaments from multiple system atrophy

Prion-like templated seeding of a-synuclein filaments is thought to underlie the spreading of multiple system atrophy (MSA) and other synucleinopathies through the brain. Here, we used -synuclein filaments extracted from the brains of individuals with MSA to induce seeded aggregation in undifferentiated human neuroblastoma SH-SY5Y cells, human iNeurons, mixed primary murine cortical cells and murine oligodendrocyte-enriched primary cultures, all overexpressing human -synuclein, followed by determination of the cryo-EM structures of the seeded filaments. Whereas MSA seeds comprise two protofilaments with an unidentified non-proteinaceous density located between protofilaments, seeding resulted in the formation of filaments with a single protofilament. Only the seeded structures derived from oligodendrocytes contained an extra density that resembled that of the seeds. This suggests that oligodendrocytes may provide the chemical component that is responsible for the extra density at the protofilament interface of MSA filaments. In support, the injection of MSA seeds into the striatum of transgenic mice expressing human -synuclein under the control of the oligodendrocyte-specific proteolipid protein promoter, also yielded seeded filaments with a single protofilament and a similar extra density.

neuroscience↗

bioRxiv2025

Multiparametric MRI and imaging transcriptomics reveal molecular and cellular correlates of neurodegeneration in experimental multiple system atrophy

Multiple system atrophy (MSA) is an atypical Parkinsonian disorder marked by oligodendroglial -synucleinopathy and selective neurodegeneration. Although MRI can capture regional atrophy and microstructural alterations in MSA brain, the molecular substrates underlying these phenotypes remain poorly defined. Imaging transcriptomics provides a computational framework to relate spatial imaging patterns to brain-wide gene expression. While this approach has been applied to human MSA, interpretation is constrained by limited experimental control and lack of disease-matched molecular validation. Here, we apply imaging transcriptomics in a controlled preclinical setting by integrating high-resolution ex vivo multimodal MRI with transcriptomic mapping in the PLP-Syn mouse model of MSA. Structural and diffusion MRI revealed distinct patterns of regional atrophy and microstructural abnormalities. Atlas-based analyses associated imaging phenotypes to gene programs related to oligodendrocyte biology, energy metabolism, and neuroinflammation, with modality-specific signatures. These associations were supported by independent RNA-sequencing and showed convergence with human MSA findings. Our work benchmarks MRI-transcriptomic relationships in MSA and provides a translational framework for interpreting imaging biomarkers in synucleinopathies.

neuroscience↗

bioRxiv2025

Pharmacologic NLRP3 Inhibition Modulates Parkinson's Disease-Associated Microglial Transcriptomic Signatures and Mitigates α-Synuclein-Triggered Neurodegeneration

BackgroundParkinsons disease (PD), the second most common neurodegenerative disorder after Alzheimers disease, and the rare disorder multiple system atrophy (MSA), are both characterized by intracellular accumulation of -synuclein fibrils and early, sustained microglial reactivity in parallel to the neurodegeneration. Activation of the NLRP3 inflammasome in disease-associated reactive microglia is increasingly recognized as a key pathogenic driver and a promising therapeutic target in synucleinopathies. Dapansutrile (OLT1177(R)) is a selective, orally bioavailable NLRP3 inhibitor with a favorable safety profile in clinical trials for non-neurological indications. Here, we evaluated the therapeutic potential of dapansutrile in preclinical models of PD and MSA and explored the predictive and translational value of its effects. MethodsTwo established mouse models of synucleinopathy with nigral neurodegeneration were employed: the -synuclein preformed fibril (PFF) propagation model and the transgenic PLP--syn model expressing human wild-type -synuclein in oligodendrocytes. Pharmacokinetic analyses assessed plasma and brain exposure after oral administration. The efficacy of six-month dapansutrile treatment was examined in both preventive (post-PFF injection) and therapeutic (PLP--syn mice) paradigms, using behavioral, histopathological, and molecular readouts. Transcriptomic profiling of striatal and midbrain microglia identified differentially expressed genes (DEGs) associated with treatment and compared them with post-mortem transcriptomic signatures of disease-associated microglia in PD patients. Plasma IL-18 and neurofilament light chain (NfL) levels were evaluated as translational biomarkers. ResultsChronic oral dapansutrile treatment at clinically relevant doses improved motor performance, reduced -synuclein inclusions, attenuated gliosis, and mitigated nigral neurodegeneration in both models. Microglial transcriptomic analyses revealed that dapansutrile reversed key transcriptional signatures characteristic of PD-associated reactive microglia. Moreover, plasma IL-18 and NfL levels correlated with neuropathological and functional outcomes, supporting their potential as biomarkers of target engagement and treatment efficacy. ConclusionsThese data identify chronic NLRP3 activation as a shared and targetable mechanism in PD and MSA and highlight dapansutrile as a CNS-penetrant, clinically advanced candidate for disease modification in -synucleinopathies. The observed transcriptomic reprogramming of microglia and the parallel changes in blood biomarkers provide a strong translational bridge to clinical development.

neuroscience↗

bioRxiv2025

Human- and Rodent-derived Extracellular Vesicles Mediate the Spread of Pathology in MSA-like Models

Multiple system atrophy (MSA) is characterized by the presence of protein-rich inclusions mainly within oligodendrocytes, comprised primarily by the neuronal protein Synuclein and the oligodendroglial-specific phosphoprotein TPPP/p25. Mature oligodendrocytes do not normally express detectable Synuclein levels, suggesting that its oligodendroglial accumulation may arise from intercellular transfer, potentially via extracellular vesicles (EVs); however the precise role of oligodendroglial-derived EVs in MSA progression remains relatively understudied. Herein, we characterized the cargo/features and pathogenic potential of EVs released by oligodendrocytes treated with human Synuclein fibrils amplified from MSA or Parkinsons disease patient brains (or human recombinant Synuclein fibrils) and EVs isolated from murine and human MSA (or respective control) brains. Our findings reveal that both oligodendroglial cell- and brain-derived EVs harbor pathological Synuclein and TPPP/p25 conformations, similar to those accumulating in human MSA brains. These EVs are readily taken up by both neurons and oligodendrocytes, driving Synuclein propagation in vitro. Importantly, inoculation of these MSA-like EVs in animal models induce robust pSer129-Synuclein accumulation along the nigrostriatal axis, colocalizing with markers of mature oligodendrocytes and dopaminergic neurons. These findings underscore the pivotal role of oligodendroglial-derived EVs in pathology progression and neuronal-oligodendroglial communication, positioning them as promising targets for therapeutic strategies aimed at combating alpha-Synucleinopathies.

neuroscience↗

bioRxiv2022

Rapid iPSC inclusionopathy models shed light on formation, consequence and molecular subtype of alpha-synuclein inclusions

Intracellular inclusions accompanying neurodegeneration are histopathologically and ultrastructurally heterogeneous but the significance of this heterogeneity is unclear. iPSC models, while promising for disease modeling, do not form inclusions in a reasonable timeframe and suffer from limited tractability. Here, we developed an iPSC toolbox utilizing piggyBac-based or targeted transgenes to rapidly induce CNS cells with concomitant expression of aggregation-prone proteins. This system is amenable to screening and longitudinal tracking at single-cell and single-inclusion resolution. For proof-of-principle, cortical neuron -synuclein "inclusionopathy" models were engineered to form inclusions through exogenous seeding or -synuclein mutation. These models recapitulated known fibril- and lipid-rich inclusion subtypes, uncovering dynamic interactions between them, and refined the classification of inclusions in postmortem brain. Genetic-modifier and protein-interaction screens pinpointed proteins like RhoA whose sequestration into specific inclusion subtypes is likely to be toxic. This iPSC platform should enhance our understanding of proteinaceous pathologies in neurodegeneration and facilitate therapeutics development.

neuroscience↗

bioRxiv2020

a-Synuclein strains influence multiple system atrophy via central and peripheral mechanisms

Multiple system atrophy (MSA) is a progressive neurodegenerative disease with prominent autonomic and motor features. Different disease subtypes are distinguished by their predominant parkinsonian or cerebellar signs. The pathognomonic feature of MSA is the presence of -synuclein (Syn) protein deposits in glial cells of the central and peripheral nervous system. It is unclear why MSA, that invariably presents with Syn pathology, is clinically so heterogeneous, why it progresses at varying rates and how neuroinflammation affects disease progression. Recently, it was shown that different strains of Syn can assemble in unique disease environments but also that a variety of strains might exist in the brain of MSA patients. We therefore investigated if different Syn strains might influence MSA disease progression. To this aim, we injected two recombinant strains of Syn in MSA transgenic mice and found that they significantly impact MSA disease progression in a strain-dependent way via oligodendroglial, neurotoxic and immune-related mechanisms. Neurodegeneration and brain atrophy were accompanied by unique microglial and astroglial responses and the recruitment of central and peripheral immune cells. The differential activation of microglial cells correlated with the structural features of Syn strains both in vitro and in vivo. By injecting Syn strains in MSA mice we could more closely mimic a comprehensive MSA phenotype in an experimental setting. This study therefore shows that i) MSA phenotype is governed by both the Syn strain nature and the host environment and ii) Syn strains can directly trigger a detrimental immune response related to disease progression in MSA.

neuroscience↗

bioRxiv2020

Transcriptional profiling of Multiple System Atrophy cerebellar tissue highlights differences between the parkinsonian and cerebellar sub-types of the disease

Multiple system atrophy (MSA) is a rare adult-onset neurodegenerative disease of unknown cause, with no effective therapeutic options, and no cure. Limited work to date has attempted to characterize the transcriptional changes associated with the disease, which presents as either predominating parkinsonian (MSA-P) or cerebellar (MSC-C) symptoms. We report here the results of RNA expression profiling of cerebellar white matter (CWM) tissue from two independent cohorts of MSA patients (n=66) and healthy controls (HC; n=66). RNA samples from bulk brain tissue and from oligodendrocytes obtained by laser capture microdissection (LCM) were sequenced. Differentially expressed genes (DEGs) were obtained and were examined before and after stratifying by MSA clinical sub-type. We detected the highest number of DEGs in the MSA-C group (n = 747) while only one gene was noted in MSA-P, highlighting the larger dysregulation of the transcriptome in the MSA-C CWM. Results from both bulk tissue and LCM analysis of MSA-C showed a downregulation of oligodendrocyte genes and an enrichment for myelination processes with a key role noted for the QKI gene. Additionally, we observed a significant upregulation of neuron-specific gene expression in MSA-C and an enrichment for synaptic processes. A third cluster of genes was associated with the upregulation of astrocyte and endothelial genes, two cell types with a key role in inflammation processes. Finally, network analysis in MSA-C showed enrichment for {beta}-amyloid related functional classes, including the known Alzheimers disease (AD) genes, APP and PSEN1. This is the largest RNA profiling study ever conducted on post-mortem brain tissue from MSA patients. We were able to define specific gene expression signatures for MSA-C highlighting the different stages of the complex neurodegenerative cascade of the disease that included alterations in several cell-specific transcriptional programs. Finally, several results suggest a common transcriptional dysregulation between MSA and AD-related genes despite the clinical and neuropathological distinctions between the two diseases.

genomics↗

bioRxiv2019

A genome-wide genetic pleiotropy approach identified shared loci between multiple system atrophy and inflammatory bowel disease

We aimed to identify shared genetic background between multiple system atrophy (MSA) and autoimmune diseases by using the conjFDR approach. Our study showed significant genetic overlap between MSA and inflammatory bowel disease and identified DENND1B, C7, and RSP04 loci, which are linked to significant changes in methylation or expression levels of adjacent genes. We obtained evidence of enriched heritability involving immune/digestive categories. Finally, an MSA mouse model showed dysregulation of the C7 gene in the degenerating midbrain compared to wildtype mice. The results identify novel molecular mechanisms and implicate immune and gut dysfunction in MSA pathophysiology.

genetics↗