Multiple system atrophy (MSA) is a rare, fatal neurodegenerative disease, pathologically characterized by glial cytoplasmic inclusions (GCIs) containing α-synuclein (αSyn). The causes leading to aberrant αSyn accumulation in oligodendroglia remain unknown. Recent evidence of increased αSyn mRNA in GCI-bearing oligodendrocytes suggests that oligodendroglia αSyn expression may be a key determinant of GCI formation. To ascertain this, we generated a new transgenic (TG) mouse line overexpressing human (h-) αSyn through the myelin basic protein promoter (MBP-hSNCA mice). Immunofluorescence combined with machine learning-based classification confirmed age-independent oligodendroglial αSyn localization, with no evidence of aggregated and pathological αSyn, as assessed by a FRET-based assay, biochemical fractionation, and the seed amplification assay (SAA). Upon intrastriatal inoculation of hαSyn preformed fibrils (hPFFs), the fraction of oligodendroglial αSyn positive insoluble aggregates increased over time in TG compared to wildtype (WT) mice, reaching significance six to nine months after inoculation. This was accompanied by an increase in brain αSyn seeding potency. As proof of concept, we investigated whether preferential oligodendroglia vulnerability is influenced by intrinsic fibril potency by intrastriatally injecting TG and WT mice with αSyn fibrils amplified from 2 MSA or 1 PD patient's brains. Six months post inoculation, MSA-inoculated brains retained the MSA-characteristic seeding profile and exhibited higher seeding potency compared to PD-inoculated mice. TG mice showed significantly more widespread phosphorylated αSyn (pSyn) pathology than WT, independent of whether they were seeded with MSA- or PD-fibrils. However, oligodendroglial inclusions were significantly more abundant in TG mice injected with MSA-derived αSyn. In conclusion, our results indicate that intracellular αSyn expression facilitates the development of oligodendroglial pathology, supporting the hypothesis that increased αSyn expression may represent a rate-limiting step in GCI formation.

Untreated hypertension is a risk factor for late-onset Alzheimer’s disease (AD); however, this association is not well understood. The aim of this study was to reveal protein signatures that bridge the pathophysiological changes in hypertension to AD. Using untargeted proteomics, we analyzed brain samples from aged (30- and 40-week-old) spontaneously hypertensive rats (SHRs, n = 12), and age-matched normotensive Wistar Kyoto (WKY, n = 8) controls, and human AD patients (Braak stages 4–6) (n = 30), cerebral amyloid angiopathy (CAA) (n = 5), non-demented controls (Braak stages 0–3) (n = 37). Differential expression and pathway analyses in SHRs highlighted the ‘extracellular exosome’ pathway. This pathway also showed significant associations to differentially expressed proteins in AD and CAA patients. Comparison between species identified 24 proteins in SHRs and AD, whose trajectory pattern over the progression of hypertension, aligned with those observed during AD Braak stage progression, compared to respective controls. The proteins were similarly associated with extracellular exosomes. Immunostaining and spatial proteomics support vesicle accumulation and dysregulated exosome protein signatures in the cerebrovasculature of both SHR and AD brains. Additionally, the extracellular exosome pathway-association was not identified in a traditional model of familial AD (5xFAD). Our findings demonstrate cross-species translatability between AD and the SHR and provide novel mechanistic insights into a shared dysregulation of cerebral artery-associated exosomes.

Multiple System Atrophy (MSA) and Parkinson's Disease (PD) are neurodegenerative diseases characterized by abundant α-synuclein (αSyn) aggregation in the brain. Compared to PD patients, MSA patients have more widespread neurodegeneration and a more aggressive disease course. PD-related αSyn pathology is primarily neuronal, whereas MSA brains characteristically display oligodendroglial inclusions. The strain hypothesis poses that polymorphisms of the αSyn aggregates, so-called strains, may explain disease heterogeneity. The present study investigates the differential properties of αSyn fibrils derived from MSA and PD patients' brains using the protein misfolding cyclic amplification (PMCA) method in cultured neurons and in vivo. MSA- and PD-derived αSyn species were administered to primary murine neuronal cell cultures or injected intrastriatally into wildtype mice, along with de novo generated αSyn fibrils of the ribbon and fibril types. The potency to induce phosphorylated αSyn (pSyn) pathology, microglial reactivity, and the extent of oligodendroglial pSyn pathology were compared among the different seeding materials using immunohistochemical and immunofluorescent approaches. In summary, the various seeding materials induced pSyn pathology of distinguishable potency and morphology. PMCA-derived material from MSA brains and the fibril polymorph induced more pSyn pathology in both neuronal cultures and in mice compared to PMCA-derived material from PD brains and the ribbon polymorph. Interestingly, amplified material from MSA brains induced significantly more oligodendroglial pSyn aggregates than amplified material from PD brains. Additionally, mice injected with the fibril polymorph, showed mild changes in microglial reactivity. Our findings suggest specific properties of the MSA- and PD-derived fibrils, and overall support the strain hypothesis.

Humoral immune changes in amyotrophic lateral sclerosis (ALS) remain incompletely defined. We examined whether serum anti-TDP-43 and global immunoglobulin profiles differ before and after ALS diagnosis. Serum from 59 ALS patients contributing 108 samples and 103 normal controls (NC) was analyzed. ALS samples were classified as pALS before diagnosis and cALS at or after diagnosis. We measured TDP-43 competition binding, anti-TDP-43 IgG subclasses, anti-TDP-43 total IgG, anti-TDP-43 IgM, and global immunoglobulins. Patient-level cross-sectional, paired pALS-cALS, random-intercept mixed-effects, exploratory PCA, and patient-level ROC analyses were performed. TDP-43 competition binding did not show robust group differences or significant within-patient longitudinal change after false discovery rate correction. Anti-TDP-43 IgG1 was lower in pALS and cALS than in NC, while anti-TDP-43 total IgG was higher in both ALS groups. Anti-TDP-43 total IgG increased within ALS patients over time (beta = 0.050/year, 95% CI 0.026 to 0.073, q = 0.00023). Global immunoglobulin analyses showed lower global IgG2 and IgG3 and higher global IgG4 and IgM in ALS samples. Exploratory PCA showed partially overlapping profiles; PC1 and PC2 explained 18.7% and 17.7% of variance. Patient-level ROC analyses identified anti-TDP-43 IgG1, anti-TDP-43 total IgG, global IgG4, and global IgM as the strongest exploratory classifiers. Serum antibody profiles differed in ALS samples collected before and after diagnosis compared with NC, supporting altered humoral immunity.

Multiple system atrophy (MSA) is a rare, age-related neurodegenerative disease that shares clinical and pathological features with Parkinson's disease (PD) but presents a more devastating disease course. To elucidate the distinct cellular pathophysiology, we performed single-nucleus RNA sequencing on postmortem striatal brain tissue from 7 MSA and 12 PD patients, and 10 non-neurological cases. Here, we show significant compositional differences in astroglia and microglia subtypes, while oligodendroglia and neurons are comparable. PD brains show abundant microglia expressing MHC class II HLA haplotypes, indicative of a proinflammatory state, alongside more homeostatic astrocytes. In contrast, MSA lack activated microglia but has more reactive astrocytes compared to PD. Transcriptomic analysis suggests compromised oligodendrocyte signaling in MSA, with microglia being in a state of immune tolerance or exhaustion. Microglia derived from iPSC exposed to patient cerebrospinal fluid exhibit reduced phagocytic activity, especially in MSA. These findings underscore a dysfunctional immune response in MSA as a potential contributor to the more severe pathophysiology of MSA.

BACKGROUND:Blood-brain barrier disruption is increasingly recognized in synucleinopathies, but the role of the endothelial glycocalyx (GLX) in Parkinson's disease (PD) and multiple system atrophy (MSA) remains unclear. OBJECTIVES:The aim was to determine whether plasma GLX markers differ between PD, MSA, and healthy controls (HC), relate to clinical measures, and support differential diagnosis. METHODS:Nine GLX analytes were quantified in plasma from 38 PD, 24 MSA, and 46 HC. Group differences were tested with multilinear regression including age and sex; associations with disease duration, Hoehn and Yahr stage, and Montreal Cognitive Assessment score were examined; gradient boosting classifiers plus Shapley Additive Explanations and univariate receiver operating characteristic (ROC) analyses evaluated discriminative performance. RESULTS:PD showed reduced biglycan and cluster of differentiation 44 (CD44), whereas MSA showed increased chondroitin sulfate and reduced perlecan and CD44 versus comparators. Several GLX markers correlated with duration and cognition. Multianalyte GLX signatures classified groups with ROC area under curve, 0.79 to 0.88. CONCLUSIONS:In this exploratory cohort, distinct GLX signatures reflect disease-specific neurovascular dysfunction and may aid stratification and monitoring. © 2026 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

The Roman inbred rat strains are a neurodevelopmental model, with the Roman High Avoidance (RHA) presenting specific behaviours and frontal cortex (FC) gene expression changes relevant to schizophrenia symptoms. We wanted to assess the potentially positive modulatory and enduring effects of neonatal handling (NH) on the innate traits associated with both the RHA and their counterpart Roman Low Avoidance (RLA). Male rats received NH or were left untreated (controls). Two different age groups were considered: adolescent and adults. The assessment encompassed exploratory behaviour, social behaviour, anxiety-related behaviour (self-grooming), sensorimotor gating (prepulse inhibition; PPI), and the analysis of gene expression associated with synaptic processes, cortical maturation, and neuroplasticity in the FC. In adolescent rats, NH increased novelty exploration and activity, and reduced novelty-induced self-grooming in RLAs, whereas it improved PPI in RHAs. In adult rats, NH increased novelty-induced activity in both strains, reduced self-grooming in RLA rats, and enhanced social interaction and PPI in RHAs. NH produced significant effects on gene expression in adolescent RHA rats. These effects were observed at the presynaptic level by a reduction of Snap25 and increases of Cables1 and Cdk5, and at the postsynaptic level by increases of Grin2b, Homer1 and Nrg1, as well as by a NH-induced enhancement of Bdnf. NH also increased Nrg1 and Bdnf expression in adult RLA rats. These findings show for the first time that NH is able to modulate several genetically linked synaptic/neuroplasticity alterations in RHA vs. RLA rats, which are paralleled by NH-induced improvements in novelty exploration, social behaviour and sensorimotor gating (PPI).

AbstractExperimente zur Vermehrung geringer Mengen an Proteinaggregaten/‐fibrillen, sogenannte “seed amplification assays (SAAs)”, sind ein vielversprechendes Mittel zur frühen Diagnose von neurodegenerativen Erkrankungen. Wenn allerdings Fibrillen aus Patientenproben in Multiwell‐Platten vermehrt werden ist es momentan noch sehr schwierig deren Konzentration genau zu bestimmen. Es ist daher wünschenswert diese Art von Test in ein digitales Format zu überführen um direkte Quantifizierung der Anzahl der Fibrillen zu ermöglichen. Um einen Übergang vom gewöhnlichen Platten‐basierten zu einem mikrofluidischen digitalen Format zu ermöglichen muss eine effektive Vermehrung der Impffibrillen in den Mikroemulsionen erzielt werden. Daher etablieren wir hier eine Reihe von neuen Lösungsbedingungen die die effiziente Vermehrung von Impffibrillen (”seeds”) ohne Schütteln der Platte ermöglichen. Allerdings zeigen dieselben Lösungsbedingungen nach Überführung in das mikrofluidische Format ein ganz anderes Verhalten da dort keinerlei Vermehrung der Fibrillen beobachtet wird. Wir zeigen dass dieser Unterschied daher rührt dass alle sekundären Prozesse die die Impffibrillen vermehren könnten in Abwesenheit jeglicher mechanischer Einflüsse vollständig unterdrückt sind. Weiterhin zeigen wir dass die Vermehrung der Fibrillen innerhalb von Tröpfchen dadurch erzielt werden kann dass diese Mikroemulsionen hochfrequenten Vibrationen mittels einer Piezo‐Einheit ausgesetzt werden. Unsere Ergebnisse ermöglichen neue Einblicke in die physikalischen Bedingungen der Vermehrung von Alpha‐Synuclein Fibrillen und weisen einen Weg zur Entwicklung effektiver digitaler SAAs.

Individuals with type 2 diabetes (T2D) have an elevated risk of cognitive decline, yet the mechanisms connecting these pathologies remain unclear. Altered glucagon and insulin signaling contribute to T2D, and insulin resistance may also be associated with cognitive decline. The role of glucagon in this context is unknown. Here we aimed to characterize glucagon receptor (GCGR) expression in brain tissue and investigate the potential impact of altered GCGR signaling on dementia prevalence and cognitive function. We investigated GCGR protein expression in various human brain regions and cell types in postmortem brain samples. To explore the potential link between GCGR signaling and cognitive function, individuals with specific GCGR mutations with known or predicted impaired GCGR signaling were examined in connection to the prevalence of dementia defined by International Classification of Diseases, Tenth Revision coding and by cognitive function using population-scale cognitive tests in the UK Biobank. GCGR mRNA and protein were expressed specifically in neurons of the frontal cortex. Varying degrees of expression were observed across brain regions and with higher expression in the parietal cortex and thalamus by antibody-dependent analyses. GCGR variant carriers did not have a significantly higher prevalence of dementia, but 1 cognitive test was significantly impaired in individuals with a GCGR cAMP loss-of-function variant compared to sex- and age-matched nonvariant carrier controls. Our findings indicate GCGR expression in the human brain, particularly in neurons of the frontal cortex, and altered glucagon signaling may be associated with lower cognitive function. Further research is needed to elucidate mechanisms underlying the potential link between altered GCGR signaling and cognitive decline.

The aggregation of natively disordered α-Synuclein (αSyn) into amyloid fibrils is a hallmark of Parkinson’s and other neurodegenerative diseases. Understanding αSyn’s pathological role remains a major challenge due to its complex, context-dependent energy landscape characterized by conformational plasticity and fibril polymorphism. Here, we present a systematic mutational analysis as a quantitative probe of the αSyn energy landscape, focusing on electrostatic contributions to key aggregation pathways. We engineered αSyn variants with one to eight lysine-to-glutamine substitutions and analyzed their aggregation under controlled conditions to delineate their effects on nucleation, elongation, seed amplification, fibril stability, and fibril polymorphism. We find that αSyn aggregation from a homogenous solution can be modelled well using global properties, including protein concentration, charge, and ionic strength. Microscopic pathways and the resulting fibril polymorphs are instead modulated by sequence-specific effects. We identify mutations of residues found in fibril cores as perturbations that significantly modify the αSyn free energy landscape, creating pathways and energy minima not accessible to the WT under the same experimental conditions. In contrast, mutations outside of the fibril core affect the magnitude of the relevant energy barriers whilst overall maintaining a WT-like free energy landscape. Our work outlines a scalable, quantitative framework that increases the informational output of the mutational studies of αSyn using conventional assays. The approach can be extended by incorporating additional mutational and functional data to deepen our understanding of αSyn’s energy landscape and its role in health and disease. ### Competing Interest Statement The authors have declared no competing interest. Novo Nordisk Foundation, https://ror.org/04txyc737, NNF17SA0028392, NNF21OC0065495 European Research Council, https://ror.org/0472cxd90, 101088163 EMMA Lundbeck Foundation, https://ror.org/03hz8wd80, R366-2021-169 STADIC European Commission, https://ror.org/00k4n6c32, MSCA-101106115

Parkinson's disease (PD), Dementia with Lewy bodies (DLB), and multiple system atrophy (MSA), are characterized by the misfolding and aggregation of alpha-synuclein (αSyn). Compelling evidence showed that αSyn aggregates exist as distinct conformational strains in different synucleinopathies. Recently, we reported that the αSyn Seed Amplification Assay (αSyn-SAA) can amplify and distinguish αSyn strains from PD and MSA. In this study, we investigate whether MSA-seeded, SAA-amplified αSyn fibrils retain the biological and structural properties of the αSyn seeds present in MSA brains. We study the biological activities of both brain-derived and SAA-amplified αSyn aggregates using an αSyn "biosensor" cell model and a synucleinopathy transmission mouse model. Our in vitro and in vivo findings reveal that the SAA-amplified αSyn fibrils preserve the biological properties of the brain-derived MSA strain. Detailed analyses of the in vivo studies demonstrate that both brain-derived and SAA-generated αSyn aggregates induce a similar disease, with comparable incubation periods, neuropathological damages and clinical manifestations. High-resolution cryo-EM analysis of SAA-amplified αSyn fibrils demonstrates that their conformation at the protofilament level closely resembles one of the αSyn filaments previously identified in MSA patient brains. Our findings suggest that SAA can amplify disease-specific misfolded αSyn conformation while preserving its main biological properties.

Seed amplification assays (SAAs) are a promising avenue for the early diagnosis of neurodegenerative diseases. However, when amplifying fibrils from patient-derived samples in multiwell plates, it is currently highly challenging to accurately quantify the aggregates. It is therefore desirable to transfer such assays into a digital format in microemulsion droplets to enable direct quantification of aggregate numbers. To achieve transfer from conventional plate-based to the microfluidic digital format, effective seed amplification needs to be achieved inside the microdroplets. Therefore, we establish a new set of assay conditions that enable highly efficient seed amplification in plates without any shaking. However, the same set of conditions displayed a very different behavior upon transfer to a microfluidic platform where no amplification was observed. We demonstrate that this is caused by the suppression of all secondary processes that could amplify the seeds in the complete absence of mechanical perturbations inside the microdroplets. We further show that the amplification inside droplets can be achieved by subjecting the microemulsions to high-frequency vibrations using a piezo device. Taken together, our results provide novel insights into the physical requirements of alpha-synuclein seed amplification and demonstrate a pathway towards the development of effective digital SAAs.

Tau protein aggregates are a key pathological hallmark of Alzheimer’s disease (AD) and are closely associated with cognitive decline and neurodegeneration. It is proposed that tau aggregates faithfully propagate throughout the brain by self-templating their disease-associated conformation onto natively-folded tau monomers, thereby inducing their aggregation and incorporation into growing fibrils. As such, the inhibition or modulation of tau seeding and aggregation represents a viable therapeutic strategy for AD and other tauopathies. We have recently developed seed amplification assays (SAA) for the detection and amplification of small quantities of misfolded protein aggregates in various neurodegenerative diseases. In this article, we adapted the SAA technology to amplify the process of tau aggregation and seeding in AD brain samples. Using the Tau-SAA we screened two chemical libraries: one comprising over 20 suspected aggregation inhibitors and the other comprising over 200 FDA-approved, blood-brain barrier-permeable compounds from a commercial chemical library. We also performed secondary in vitro assays to confirm the activity of selected hits as well as determining the IC50 of the most active compounds. Our Tau-SAA detects the presence of tau seeds even after a 100-million-fold dilution of the initial inoculum. Examination of 26 postmortem brain samples from AD and control cases confirmed that our assay is specific for AD brain tau seeds. Screening of 220 compounds showed that approximately 57

Aggregation of the intrinsically disordered protein alpha-synuclein into amyloid fibrils and their subsequent intracellular accumulation are hallmark features of several neurodegenerative disorders, including Parkinson's disease, for which no curative treatments currently exist. In this study, we investigate the relationship between fibril morphology, thermodynamic stability, and susceptibility to disaggregation by the human chaperone system comprising HSP70, DNAJB1, and Apg2. By varying assembly conditions and incubation times, we generated alpha-synuclein fibrils with diverse morphological and biochemical properties, including a broad range of thermodynamic stabilities, which we quantified using a chemical depolymerization assay. The chaperone system effectively disaggregated three of the four fibril types, with efficiencies that correlated with their thermodynamic stabilities. One fibril type resisted disaggregation despite exhibiting a comparable stability to those that were disaggregated, suggesting that additional structural features influence chaperone susceptibility. Our findings establish a quantitative link between fibril stability and chaperone-mediated disaggregation for three in vitro αSyn fibril types as well as fibrils amplified from brain extracts of PD but not MSA patients, highlighting the importance of fibril thermodynamics in biologically relevant disaggregation processes and disease pathology.

Alzheimer’s disease (AD) and Parkinson’s disease (PD) are leading neurodegenerative disorders marked by protein aggregation, with AD featuring amyloid-beta (Aβ) and tau proteins, and PD alpha-synuclein (αSyn). Dementia with Lewy bodies (DLB) often presents with a mix of these pathologies. This study explores naturally occurring autoantibodies (nAbs), including Immunoglobulin (Ig)G, IgM, and IgA, which target αSyn, Aβ and tau to maintain homeostasis and were previously found altered in AD and PD patients, among others. We extended this investigation across AD, PD and DLB patients investigating both the affinities of IgGs and levels of IgGs, IgMs and IgAs towards αSyn, Aβ and tau utilizing chemiluminescence assays. We confirmed that AD and PD patients exhibited lower levels of high-affinity anti-Aβ and anti-αSyn IgGs, respectively, than healthy controls. AD patients also showed diminished levels of high-affinity anti-αSyn IgGs, while anti-tau IgG affinities did not differ significantly across groups. However, DLB patients exhibited increased anti-αSyn IgG but decreased anti-αSyn IgM levels compared to controls and PD patients, with AD patients showing a similar pattern. Interestingly, AD patients had higher anti-Aβ IgG but lower anti-Aβ IgA levels than DLB patients. DLB patients had reduced anti-Aβ IgM levels compared to controls, and anti-tau IgG levels were lower in AD than PD patients, who had reduced anti-tau IgM levels compared to controls. AD patients uniquely showed higher anti-tau IgA levels. Significant correlations were observed between clinical measures and nAbs, with negative correlations between anti-αSyn IgG affinity and levels in DLB patients and a positive correlation with anti-αSyn IgA levels in PD patients. Disease-specific changes in nAb levels and affinity correlations were identified, highlighting altered immune responses. This study reveals distinctive nAb profiles in AD, DLB, and PD, pinpointing specific immune deficiencies against pathological proteins. These insights into the autoreactive immune system’s role in neurodegeneration suggest nAbs as potential markers for vulnerability to protein aggregation, offering new avenues for understanding and possibly diagnosing these conditions.

This study investigates the presence of antinuclear antibodies (ANA) in three primary synucleinopathies - Parkinson's disease (PD), multiple system atrophy (MSA), and dementia with Lewy bodies (DLB), compared to healthy controls. Autoinflammatory disorders typically involve the immune system mistakenly attacking the body's own cells and start producing ANA. There is an increasing body of evidence that immune-mediated inflammation is a pathological feature linked to synucleinopathies. To investigate whether this could be autoimmune mediated we analyzed for ANA in the plasma of 25 MSA, 25 PD, and 17 DLB patients, along with 25 healthy controls, using the ANA HEp-2 indirect immunofluorescence antibody assay (ANA HEp-2 IFA). Contrary to initial expectations, results showed ANA HEp-2 positivity in 12% of PD, 8% of MSA patients, 18% of DLB patients, and 17% of healthy controls, indicating no increased prevalence of ANA in synucleinopathies compared to age-matched healthy individuals. Various ANA HEp-2 patterns were identified, but no specific pattern was associated with individual synucleinopathies. We conclude hereby that synucleinopathies are not associated with detectable presence of ANA in plasma.

Synucleinopathies are a group of diseases characterized by brain aggregates of α-synuclein (α-syn). The gradual accumulation of α-syn and the role of inflammation in early-stage pathogenesis remain poorly understood. We explored this interaction by inducing chronic inflammation in a common pre-clinical synucleinopathy mouse model. Three weeks post unilateral intra-striatal injections of human α-syn pre-formed fibrils (PFF), mice underwent repeated intraperitoneal injections of 1 mg/ml lipopolysaccharide (LPS) for 3 weeks. Histological examinations of the ipsilateral site showed phospho-α-syn regional spread and LPS-induced neutrophil recruitment to the brain vasculature. Biochemical assessment of the contralateral site confirmed spreading of α-syn aggregation to frontal cortex and a rise in intracerebral TNF-α, IL-1β, IL-10 and KC/GRO cytokines levels due to LPS. No LPS-induced exacerbation of α-syn pathology load was observed at this stage. Proteomic analysis was performed contralateral to the PFF injection site using LC-MS/MS. Subsequent downstream Reactome Gene-Set Analysis indicated that α-syn pathology alters mitochondrial metabolism and synaptic signaling. Chronic LPS-induced inflammation further lead to an overrepresentation of pathways related to fibrin clotting as well as integrin and B cell receptor signaling. Western blotting confirmed a PFF-induced increase in fibrinogen brain levels and a PFF + LPS increase in Iba1 levels, indicating activated microglia. Splenocyte profiling revealed changes in T and B cells, monocytes, and neutrophils populations due to LPS treatment in PFF injected animals. In summary, early α-syn pathology impacts energy homeostasis pathways, synaptic signaling and brain fibrinogen levels. Concurrent mild systemic inflammation may prime brain immune pathways in interaction with peripheral immunity.

DNAJB6 is a suppressor of α-synuclein aggregation in vivo and in vitro. DNAJB6 is strongly expressed in the brain, and its overall protein expression is altered in neurodegenerative conditions such as Parkinson's Disease (PD) and Multiple System Atrophy (MSA). These two diseases are characterized by accumulation of aggregated α-synuclein in neurons and oligodendrocytes, respectively. To further explore this, we employed post-mortem normal human brain material to investigate the regional and cell type specific protein expression of DNAJB6. We found that the DNAJB6 protein is ubiquitously expressed across various regions of the brain. Notably, we demonstrate for the first time that DNAJB6 is present in nearly half (41%-53%) of the oligodendrocyte population and in the majority (68%-80%) of neurons. However, DNAJB6 was only sparsely present in other cell types such as astrocytes and microglia. Given that α-synuclein aggregation in oligodendrocytes is a hallmark of MSA, we investigated DNAJB6 presence in MSA brains compared to control brains. We found no significant difference in the percentage of oligodendrocytes where DNAJB6 was present in MSA brains relative to control brains. In conclusion, our results reveal an expression of the DNAJB6 protein across various regions of the human brain, and that DNAJB6 is almost exclusively present in neurons and oligodendrocytes. Since prior studies have shown that PD and MSA brains have altered levels of DNAJB6 relative to control brains, DNAJB6 may be an interesting target for drug development.