Multiple System Atrophy: An Oligodendroglioneural Synucleinopathy1

DNAJB6 is expressed in neurons and oligodendrocytes of the human brain

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.

CNS macrophage contributions to myelin health

Myelin is the membrane surrounding neuronal axons in the central nervous system (CNS), produced by oligodendrocytes to provide insulation for electrical impulse conduction and trophic/metabolic support. CNS dysfunction occurs following poor development of myelin in infancy, myelin damage in neurological diseases, and impaired regeneration of myelin with disease progression in aging. The lack of approved therapies aimed at supporting myelin health highlights the critical need to identify the cellular and molecular influences on oligodendrocytes. CNS macrophages have been shown to influence the development, maintenance, damage and regeneration of myelin, revealing critical interactions with oligodendrocyte lineage cells. CNS macrophages are comprised of distinct populations, including CNS-resident microglia and cells associated with CNS border regions (the meninges, vasculature, and choroid plexus), in addition to macrophages derived from monocytes infiltrating from the blood. Importantly, the distinct contribution of these macrophage populations to oligodendrocyte lineage responses and myelin health are only just beginning to be uncovered, with the advent of new tools to specifically identify, track, and target macrophage subsets. Here, we summarize the current state of knowledge on the roles of CNS macrophages in myelin health, and recent developments in distinguishing the roles of macrophage populations in development, homeostasis, and disease.

Neuropsychiatric Manifestations of Degenerative Cerebellar Ataxia

BACKGROUND/OBJECTIVES

Degenerative cerebellar ataxias (DCA) present a group of complex neurological disorders primarily affecting the cerebellum and its pathways. Classic manifestations include motor symptoms of cerebellar ataxia. However, emerging evidence suggests that the cerebellum also plays a crucial role in various cognitive and emotional processes. The objective was to assess the psychiatric profile of a heterogeneous group of patients with degenerative cerebellar ataxia.

METHODS

Our sample comprised 107 participants diagnosed with cerebellar degenerative ataxia. All patients were clinically evaluated using SARA, INAS, and different neuropsychiatric scales (ACE-R, HAMA, HAMD, AS, and GAF).

RESULTS

The majority of patients had autosomal dominant ataxia (38.3%) followed by sporadic ataxia (32.7%) with an average age at the moment of diagnosis of 35.3 ± 16.23 years, while the mean duration of disease at the study beginning was 12.1 ± 9.9 years. Psychiatric disorders were present in 40 patients (37.4%), with dysthymia (14.2%), major depressive disorder (9.4%), and MDD with melancholic features (7.6%). The presence of MDD with melancholic features was statistically significantly correlated with a lower ACE-R total score (r = -0.223; p = 0.022), while dysthymia was statistically significantly associated with a shorter duration of the disease (r = -0.226; p = 0.020) and older age (r = 0.197; p = 0.043). Statistically significant differences were observed between MSA-C patients and those with sporadic ataxia (HDRS p < 0.001, HARS p < 0.001, Apathy Scale p = 0.003, and GAF p = 0.004).

CONCLUSIONS

Based on our findings, we can conclude that the degree of motor deficit has a significant impact on the development of psychiatric disorders, including depression, anxiety, and apathy. However, it is not the only factor, and the impact also depends on the type of DCA.

A rapidly progressive multiple system atrophy-cerebellar variant model presenting marked glial reactions with inflammation and spreading of α-synuclein oligomers and phosphorylated α-synuclein aggregates

Multiple system atrophy (MSA) is a severe α-synucleinopathy facilitated by glial reactions; the cerebellar variant (MSA-C) preferentially involves olivopontocerebellar fibres with conspicuous demyelination. A lack of aggressive models that preferentially involve olivopontocerebellar tracts in adulthood has hindered our understanding of the mechanisms of demyelination and neuroaxonal loss, and thus the development of effective treatments for MSA. We therefore aimed to develop a rapidly progressive mouse model that recaptures MSA-C pathology. We crossed Plp1-tTA and tetO-SNCA*A53T mice to generate Plp1-tTA::tetO-SNCA*A53T bi-transgenic mice, in which human A53T α-synuclein-a mutant protein with enhanced aggregability-was specifically produced in the oligodendrocytes of adult mice using Tet-Off regulation. These bi-transgenic mice expressed mutant α-synuclein from 8 weeks of age, when doxycycline was removed from the diet. All bi-transgenic mice presented rapidly progressive motor deterioration, with wide-based ataxic gait around 22 weeks of age and death around 30 weeks of age. They also had prominent demyelination in the brainstem/cerebellum. Double immunostaining demonstrated that myelin basic protein was markedly decreased in areas in which SM132, an axonal marker, was relatively preserved. Demyelinating lesions exhibited marked ionised calcium-binding adaptor molecule 1-, arginase-1-, and toll-like receptor 2-positive microglial reactivity and glial fibrillary acidic protein-positive astrocytic reactivity. Microarray analysis revealed a strong inflammatory response and cytokine/chemokine production in bi-transgenic mice. Neuronal nuclei-positive neuronal loss and patchy microtubule-associated protein 2-positive dendritic loss became prominent at 30 weeks of age. However, a perceived decrease in tyrosine hydroxylase-positive neurons in the substantia nigra pars compacta in bi-transgenic mice compared with wild-type mice was not significant, even at 30 weeks of age. Wild-type, Plp1-tTA, and tetO-SNCA*A53T mice developed neither motor deficits nor demyelination. In bi-transgenic mice, double immunostaining revealed human α-synuclein accumulation in neurite outgrowth inhibitor A (Nogo-A)-positive oligodendrocytes beginning at 9 weeks of age; its expression was further increased at 10 to 12 weeks, and these increased levels were maintained at 12, 24, and 30 weeks. In an α-synuclein-proximity ligation assay, α-synuclein oligomers first appeared in brainstem oligodendrocytes as early as 9 weeks of age; they then spread to astrocytes, neuropil, and neurons at 12 and 16 weeks of age. α-Synuclein oligomers in the brainstem neuropil were most abundant at 16 weeks of age and decreased thereafter; however, those in Purkinje cells successively increased until 30 weeks of age. Double immunostaining revealed the presence of phosphorylated α-synuclein in Nogo-A-positive oligodendrocytes in the brainstem/cerebellum as early as 9 weeks of age. In quantitative assessments, phosphorylated α-synuclein gradually and successively accumulated at 12, 24, and 30 weeks in bi-transgenic mice. By contrast, no phosphorylated α-synuclein was detected in wild-type, tetO-SNCA*A53T, or Plp1-tTA mice at any age examined. Pronounced demyelination and tubulin polymerisation, promoting protein-positive oligodendrocytic loss, was closely associated with phosphorylated α-synuclein aggregates at 24 and 30 weeks of age. Early inhibition of mutant α-synuclein expression by doxycycline diet at 23 weeks led to fully recovered demyelination; inhibition at 27 weeks led to persistent demyelination with glial reactions, despite resolving phosphorylated α-synuclein aggregates. In conclusion, our bi-transgenic mice exhibited progressively increasing demyelination and neuroaxonal loss in the brainstem/cerebellum, with rapidly progressive motor deterioration in adulthood. These mice showed marked microglial and astrocytic reactions with inflammation that was closely associated with phosphorylated α-synuclein aggregates. These features closely mimic human MSA-C pathology. Notably, our model is the first to suggest that α-synuclein oligomers may spread from oligodendrocytes to neurons in transgenic mice with human α-synuclein expression in oligodendrocytes. This model of MSA is therefore particularly useful for elucidating the in vivo mechanisms of α-synuclein spreading from glia to neurons, and for developing therapies that target glial reactions and/or α-synuclein oligomer spreading and aggregate formation in MSA.

Alpha-synuclein, autophagy-lysosomal pathway, and Lewy bodies: Mutations, propagation, aggregation, and the formation of inclusions

Research into the pathophysiology of Parkinson's disease (PD) is a fast-paced pursuit, with new findings about PD and other synucleinopathies being made each year. The involvement of various lysosomal proteins, such as TFEB, TMEM175, GBA, and LAMP1/2, marks the rising awareness about the importance of lysosomes in PD and other neurodegenerative disorders. This, along with recent developments regarding the involvement of microglia and the immune system in neurodegenerative diseases, has brought about a new era in neurodegeneration: the role of proinflammatory cytokines on the nervous system, and their downstream effects on mitochondria, lysosomal degradation, and autophagy. More effort is needed to understand the interplay between neuroimmunology and disease mechanisms, as many of the mechanisms remain enigmatic. α-synuclein, a key protein in PD and the main component of Lewy bodies, sits at the nexus between lysosomal degradation, autophagy, cellular stress, neuroimmunology, PD pathophysiology, and disease progression. This review revisits some fundamental knowledge about PD while capturing some of the latest trends in PD research, specifically as it relates to α-synuclein.

White Matter Abnormalities Track Disease Progression in Multiple System Atrophy

BACKGROUND

White matter (WM) abnormalities have been implicated in clinically relevant functional decline in multiple system atrophy (MSA).

OBJECTIVE

To identify the WM and gray matter (GM) abnormalities in MSA and assess the utility of longitudinal structural and diffusion changes as surrogate markers for tracking disease progression in MSA.

METHODS

Twenty-seven participants with early MSA [15 with clinically predominant cerebellar (MSA-C) and 12 with clinically predominant parkinsonian features (MSA-P)] and 14 controls were enrolled as a part of our prospective, longitudinal study of synucleinopathies. Using structural magnetic resonance imaging (MRI) and diffusion MRI (diffusion tensor and neurite orientation and dispersion density imaging), we analyzed whole and regional brain changes in these participants. We also evaluated temporal imaging trajectories based on up to three annual follow-up scans and assessed the impact of baseline diagnosis on these imaging biomarkers using mixed-effect models.

RESULTS

MSA patients exhibited more widespread WM changes than GM, particularly in the cerebellum and brainstem, with greater severity in MSA-C. Structural and diffusion measures in the cerebellum WM and brainstem deteriorated with disease progression. Rates of progression of these abnormalities were similar in both MSA subtypes, reflecting increasing overlap of clinical features over time.

CONCLUSION

WM abnormalities are core features of MSA disease progression and advance at similar rates in clinical MSA subtypes. Multimodal MRI imaging reveals novel insights into the distribution and pattern of brain abnormalities and their progression in MSA. Selected structural and diffusion measures may be useful for tracking disease progression in MSA clinical trials.

The association of vagal atrophy with parameters of autonomic function in multiple system atrophy and progressive supranuclear palsy

Background

Vagal atrophy is a hallmark of Parkinson's disease (PD) and has been found to be associated with autonomic dysfunction, while analyses of the vagus nerve (VN) in atypical Parkinsonian syndromes (APS) have not yet been performed. We here investigate the characteristics of the VN in multiple system atrophy (MSA) and progressive supranuclear palsy (PSP) and, in a second step, its potential as a possible biomarker for orthostatic dysregulation.

Objectives

The aim was to compare the VN pathology in MSA and PSP with healthy individuals and patients with PD as a differentiating factor and to further analyse the correlation of the VN with clinical parameters and cardiovascular response.

Design

We conducted a monocentric, cross-sectional cohort study in 41 APS patients and compared nerve ultrasound (NUS) parameters with 90 PD patients and 39 healthy controls.

Methods

In addition to a detailed neurological history and examination, several clinical severity and motor scores were obtained. Autonomic symptoms were reported in the Scales for Outcomes in Parkinson's Disease - Autonomic questionnaire. Further scores were used to detect other non-motor symptoms, quality of life and cognition. Additionally, we performed a head up tilt test (HUTT) and NUS of the VN. We conducted correlation analyses of the VN cross-sectional area (CSA) with clinical scores and the heart rate and blood pressure variability parameters of the HUTT.

Results

The examination demonstrated a high prevalence of abnormal autonomic response in both MSA (90%) and PSP (80%). The VN CSA correlated with spectral parameters of the HUTT, which are associated with sympatho-vagal imbalance. In addition, the CSA of the VN in patients with PD and PSP were significantly smaller than in healthy controls. In MSA, however, there was no marked vagal atrophy in comparison.

Conclusion

The occurrence of autonomic dysfunction was high in MSA and PSP, which underlines its impact on these syndromes. Our findings indicate a connection between vagal pathology and autonomic dysfunction and might contribute to a better comprehension of APS. To further evaluate the clinical relevance and the VN as a possible marker of autonomic dysfunction in APS, prospective longitudinal observations are necessary.

Neuropathological hallmarks in the post-mortem retina of neurodegenerative diseases

The retina is increasingly recognised as a potential source of biomarkers for neurodegenerative diseases. Hallmark protein aggregates in the retinal neuronal tissue could be imaged through light non-invasively. Post-mortem studies have already shown the presence of specific hallmark proteins in Alzheimer's disease, primary tauopathies, synucleinopathies and frontotemporal lobar degeneration. This study aims to assess proteinopathy in a post-mortem cohort with different neurodegenerative diseases and assess the presence of the primary pathology in the retina. Post-mortem eyes were collected in collaboration with the Netherlands Brain Bank from donors with Alzheimer's disease (n = 17), primary tauopathies (n = 8), synucleinopathies (n = 27), frontotemporal lobar degeneration (n = 8), mixed pathology (n = 11), other neurodegenerative diseases (n = 6), and cognitively normal controls (n = 25). Multiple cross sections of the retina and optic nerve tissue were immunostained using antibodies against pTau Ser202/Thr205 (AT8), amyloid-beta (4G8), alpha-synuclein (LB509), pTDP-43 Ser409/410 and p62-lck ligand (p62) and were assessed for the presence of aggregates and inclusions. pTau pathology was observed as a diffuse signal in Alzheimer's disease, primary tauopathies and controls with Alzheimer's disease neuropathological changes. Amyloid-beta was observed in the vessel wall and as cytoplasmic granular deposits in all groups. Alpha-synuclein pathology was observed as Lewy neurites in the retina in synucleinopathies associated with Lewy pathology and as oligodendroglial cytoplasmic inclusions in the optic nerve in multiple system atrophy. Anti-pTDP-43 generally showed typical neuronal cytoplasmic inclusion bodies in cases with frontotemporal lobar degeneration with TDP-43 and also in cases with later stages of limbic-associated TDP-43 encephalopathy. P62 showed inclusion bodies similar to those seen with anti-pTDP-43. Furthermore, pTau and alpha-synuclein pathology were significantly associated with increasing Braak stages for neurofibrillary tangles and Lewy bodies, respectively. Mixed pathology cases in this cohort consisted of cases (n = 6) with high Braak LB stages (> 4) and low or moderate AD pathology, high AD pathology (n = 1, Braak NFT 6, Thal phase 5) with moderate LB pathology, or a combination of low/moderate scores for different pathology scores in the brain (n = 4). There were no cases with advanced co-pathologies. In seven cases with Braak LB ≥ 4, LB pathology was observed in the retina, while tau pathology in the retina in the mixed pathology group (n = 11) could not be observed. From this study, we conclude that the retina reflects the presence of the major hallmark proteins associated with neurodegenerative diseases. Although low or moderate levels of copathology were found in the brains of most cases, the retina primarily manifested protein aggregates associated with the main neurodegenerative disease. These findings indicate that with appropriate retinal imaging techniques, retinal biomarkers have the potential to become highly accurate indicators for diagnosing the major neurodegenerative diseases of the brain.

Neuropathological findings and in vivo imaging correlates of the red nucleus compared to those of the substantia nigra pars compacta in parkinsonisms

INTRODUCTION

The substantia nigra pars compacta (SNc) is the key pathologic locus in neurodegenerative parkinsonian disorders. Recently, in vivo susceptibility MRI metrics were associated with postmortem glial cell density and tau burden in the SNc of parkinsonism subjects. This study investigated the red nucleus (RN), another iron-rich region adjacent to the SNc and a potential site of higher functionality in parkinsonisms.

METHODS

In vivo MRI and postmortem data were obtained from 34 parkinsonism subjects and 3 controls. Neuron density, glial cell density, and percentages of area occupied by α-synuclein and tau were quantified using digitized midbrain slides. R2* and quantitative susceptibility mapping (QSM) metrics in the RN and SNc were derived from multi-gradient echo images. Histopathology data were compared between the RN and SNc using paired t-tests. MRI-histology associations were analyzed using partial Pearson correlations.

RESULTS

The RN had greater neuron (t23 = 3.169, P = 0.004) and glial cell densities (t23 = 2.407, P = 0.025) than the SNc, whereas the SNc had greater α-synuclein (t28 = 4.614, P < 0.0001) and tau burden (t24 = 4.513, P = 0.0001). In both the RN (R2*: r = 0.47, P = 0.043; QSM: r = 0.52, P = 0.024) and SNc (R2*: r = 0.57, P = 0.01; QSM: r = 0.58, P = 0.009), MRI values were associated with glial cell density but not neuron density or α-synuclein (Ps > 0.092). QSM associated with tau burden (r = 0.49, P = 0.038) in the SNc, but not the RN.

CONCLUSIONS

The RN is resilient to parkinsonian-related pathological processes compared to the SNc, and susceptibility MRI captured glial cell density in both regions. These findings help to further our understanding of the underlying pathophysiological processes in parkinsonisms.

Exploring the Significance of Microglial Phenotypes and Morphological Diversity in Neuroinflammation and Neurodegenerative Diseases: From Mechanisms to Potential Therapeutic Targets

Studying various microglial phenotypes and their functions in neurodegenerative diseases is crucial due to the intricate nature of their phenomics and their vital immunological role. Microglia undergo substantial phenomic changes, encompassing morphological, transcriptional, and functional aspects, resulting in distinct cell types with diverse structures, functions, properties, and implications. The traditional classification of microglia as ramified, M1 (proinflammatory), or M2 (anti-inflammatory) phenotypes is overly simplistic, failing to capture the wide range of recently identified microglial phenotypes in various brain regions affected by neurodegenerative diseases. Altered and activated microglial phenotypes deviating from the typical ramified structure are significant features of many neurodegenerative conditions. Understanding the precise role of each microglial phenotype is intricate and sometimes contradictory. This review specifically focuses on elucidating recent modifications in microglial phenotypes within neurodegenerative diseases. Recognizing the heterogeneity of microglial phenotypes in diseased states can unveil novel therapeutic strategies for targeting microglia in neurodegenerative diseases. Moreover, the exploration of the use of healthy isolated microglia to mitigate disease progression has provided an innovative perspective. In conclusion, this review discusses the dynamic landscape of mysterious microglial phenotypes, emphasizing the need for a nuanced understanding to pave the way for innovative therapeutic strategies for neurodegenerative diseases.

The Pathobiology of Behavioral Changes in Multiple System Atrophy: An Update

While cognitive impairment, which was previously considered a red flag against the clinical diagnosis of multiple system atrophy (MSA), is a common symptom of this rare neurodegenerative disorder, behavioral disorders are reported in 30 to 70% of MSA patients. They include anxiety, apathy, impaired attention, compulsive and REM sleep behavior disorders (RBD), and these conditions, like depression, are early and pervasive features in MSA, which may contribute to disease progression. Despite changing concepts of behavioral changes in this synucleinopathy, the underlying pathophysiological and biochemical mechanisms are poorly understood. While specific neuropathological data are unavailable, neuroimaging studies related anxiety disorders to changes in the cortico-limbic system, apathy (and depression) to dysfunction of prefrontal-subcortical circuits, and compulsive behaviors to impairment of basal ganglia networks and involvement of orbito-frontal circuits. Anxiety has also been related to α-synuclein (αSyn) pathology in the amygdala, RBD to striatal monoaminergic deficit, and compulsive behavior in response to dopamine agonist therapy in MSA, while the basic mechanisms of the other behavioral disorders and their relations to other non-motor dysfunctions in MSA are unknown. In view of the scarcity of functional and biochemical findings in MSA with behavioral symptoms, further neuroimaging and biochemical studies are warranted in order to obtain better insight into their pathogenesis as a basis for the development of diagnostic biomarkers and future adequate treatment modalities of these debilitating comorbidities.

Tissue resident memory CD8+ T cells are present but not critical for demyelination and neurodegeneration in a mouse model of multiple system atrophy

Multiple system atrophy (MSA) is rare, fast progressing, and fatal synucleinopathy with alpha-synuclein (α-syn) inclusions located within oligodendroglia called glial cytoplasmic inclusions (GCI). Along with GCI pathology there is severe demyelination, neurodegeneration, and neuroinflammation. In post-mortem tissue, there is significant infiltration of CD8+ T cells into the brain parenchyma, however their role in disease progression is unknown. To determine the role of CD8+ T cells, a modified AAV, Olig001-SYN, was used to selectively overexpress α-syn in oligodendrocytes modeling MSA in mice. Four weeks post transduction, we observed significant CD8+ T cell infiltration into the striatum of Olig001-SYN transduced mice recapitulating the CD8+ T cell infiltration observed in post-mortem tissue. To understand the role of CD8+ T cells, a CD8 knockout mice were transduced with Olig001-SYN. Six months post transduction into a mouse lacking CD8+ T cells, demyelination and neurodegeneration were unchanged. Four weeks post transduction, neuroinflammation and demyelination were enhanced in CD8 knockout mice compared to wild type controls. Applying unbiased spectral flow cytometry, CD103+, CD69+, CD44+, CXCR6+, CD8+ T cells were identified when α-syn was present in oligodendrocytes, suggesting the presence of tissue resident memory CD8+ T (Trm) cells during MSA disease progression. This study indicates that CD8+ T cells are not critical in driving MSA pathology but are needed to modulate the neuroinflammation and demyelination response.

The 'α-synucleinopathy syndicate': multiple system atrophy and Parkinson's disease

Multiple System Atrophy (MSA) and Parkinson's diseases (PD) are elite members of the α-synucleinopathy organization. Aberrant accumulations of the protein α-synuclein characterize them. A plethora of evidence indicates the involvement of these rogue inclusions in a cascade of events that disturb cellular homeostasis resulting in neuronal dysfunction. These two neurodegenerative diseases share many features both clinically and pathologically. Cytotoxic processes commonly induced by reactive free radical species have been associated with oxidative stress and neuroinflammation, frequently reported in both diseases. However, it appears they have characteristic and distinct α-synuclein inclusions. It is glial cytoplasmic inclusions in the case of MSA while Lewy bodies manifest in PD. This is probably related to the etiology of the illness. At present, precise mechanism(s) underlying the characteristic configuration of neurodegeneration are unclear. Furthermore, the "prion-like" transmission from cell to cell prompts the suggestion that perhaps these α-synucleinopathies are prion-like diseases. The possibility of some underlying genetic foul play remains controversial. But as major culprits of pathological processes or even single triggers of PD and MSA are the same-like oxidative stress, iron-induced pathology, mitochondriopathy, loss of respiratory activity, loss of proteasomal function, microglial activation, neuroinflammation-it is not farfetched to assume that in sporadic PD and also in MSA a variety of combinations of susceptibility genes contribute to the regional specificity of pathological onset. These players of pathology, as mentioned above, in a synergistic combination, are responsible for driving the progression of PD, MSA and other neurodegenerative disorders. Elucidating the triggers and progression factors is vital for advocating disease modification or halting its progression in both, MSA and PD.

A novel mouse model for investigating α-synuclein aggregates in oligodendrocytes: implications for the glial cytoplasmic inclusions in multiple system atrophy

The aggregated alpha-synuclein (αsyn) in oligodendrocytes (OLGs) is one of the pathological hallmarks in multiple system atrophy (MSA). We have previously reported that αsyn accumulates not only in neurons but also in OLGs long after the administration of αsyn preformed fibrils (PFFs) in mice. However, detailed spatial and temporal analysis of oligodendroglial αsyn aggregates was technically difficult due to the background neuronal αsyn aggregates. The aim of this study is to create a novel mouse that easily enables sensitive and specific detection of αsyn aggregates in OLGs and the comparable analysis of the cellular tropism of αsyn aggregates in MSA brains. To this end, we generated transgenic (Tg) mice expressing human αsyn-green fluorescent protein (GFP) fusion proteins in OLGs under the control of the 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNP) promoter (CNP-SNCAGFP Tg mice). Injection of αsyn PFFs in these mice induced distinct GFP-positive aggregates in the processes of OLGs as early as one month post-inoculation (mpi), and their number and size increased in a centripetal manner. Moreover, MSA-brain homogenates (BH) induced significantly more oligodendroglial αsyn aggregates than neuronal αsyn aggregates compared to DLB-BH in CNP-SNCAGFP Tg mice, suggestive of their potential tropism of αsyn seeds for OLGs. In conclusion, CNP-SNCAGFP Tg mice are useful for studying the development and tropism of αsyn aggregates in OLGs and could contribute to the development of therapeutics targeting αsyn aggregates in OLGs.

Multiple system atrophy: an update and emerging directions of biomarkers and clinical trials

Multiple system atrophy is a rare, debilitating, adult-onset neurodegenerative disorder that manifests clinically as a diverse combination of parkinsonism, cerebellar ataxia, and autonomic dysfunction. It is pathologically characterized by oligodendroglial cytoplasmic inclusions containing abnormally aggregated α-synuclein. According to the updated Movement Disorder Society diagnostic criteria for multiple system atrophy, the diagnosis of clinically established multiple system atrophy requires the manifestation of autonomic dysfunction in combination with poorly levo-dopa responsive parkinsonism and/or cerebellar syndrome. Although symptomatic management of multiple system atrophy can substantially improve quality of life, therapeutic benefits are often limited, ephemeral, and they fail to modify the disease progression and eradicate underlying causes. Consequently, effective breakthrough treatments that target the causes of disease are needed. Numerous preclinical and clinical studies are currently focusing on a set of hallmarks of neurodegenerative diseases to slow or halt the progression of multiple system atrophy: pathological protein aggregation, synaptic dysfunction, aberrant proteostasis, neuronal inflammation, and neuronal cell death. Meanwhile, specific biomarkers and measurements with higher specificity and sensitivity are being developed for the diagnosis of multiple system atrophy, particularly for early detection of the disease. More intriguingly, a growing number of new disease-modifying candidates, which can be used to design multi-targeted, personalized treatment in patients, are being investigated, notwithstanding the failure of most previous attempts.

Degeneration of olivospinal tract in the upper cervical spinal cord of multiple system atrophy patients: Reappraisal of Helweg's triangular tract

Multiple system atrophy (MSA) is an adult-onset neurodegenerative disorder that presents with variable combinations of autonomic dysfunction, cerebellar ataxia, parkinsonism, and pyramidal signs. The inferior olivary nucleus is targeted in MSA, with a phenotype of olivopontocerebellar atrophy in particular, and involvement of the olivocerebellar tract is well known. However, degeneration of the olivospinal tract has not been studied in MSA. We examined 97 spinal cords from consecutively autopsied patients with MSA. Myelin staining revealed that 22 cords (22.7%) had small, bilateral, triangular-shaped tract degeneration in the boundary of the anterior and lateral funiculi, which appeared continuously from C1 to C5. The anatomical pathway of the degenerated tract was consistent with the description of the olivospinal tract provided by Helweg in 1888. The MSA patients showing degeneration of this tract were younger at disease onset (average: 56.4 ± 8.7 years, range: 42-74), and had longer disease duration (average: 10.1 ± 4.8 years, range: 2-25) and more severe olivopontocerebellar changes compared to other MSA patients. Quantitative analyses revealed that patients with olivospinal tract degeneration had a lower neuronal density in the inferior olivary nucleus compared to other patients. Microglial density in this tract was negatively correlated with the neuronal density in the inferior olivary nucleus. The densities of glial cytoplasmic inclusions in the inferior olivary nucleus and in the olivospinal tract were strongly correlated with each other. Neurologically healthy controls (n = 22) and disease controls with Lewy body disease (n = 30), amyotrophic lateral sclerosis (n = 30), and progressive supranuclear palsy (n = 30) did not present the olivospinal tract degeneration. Our results indicate an impairment of the neural connection between the inferior olivary nucleus and the spinal cord in MSA patients, which may develop in a descending manner.

Contrasting somatic mutation patterns in aging human neurons and oligodendrocytes

Characterizing somatic mutations in the brain is important for disentangling the complex mechanisms of aging, yet little is known about mutational patterns in different brain cell types. Here, we performed whole-genome sequencing (WGS) of 86 single oligodendrocytes, 20 mixed glia, and 56 single neurons from neurotypical individuals spanning 0.4-104 years of age and identified >92,000 somatic single-nucleotide variants (sSNVs) and small insertions/deletions (indels). Although both cell types accumulate somatic mutations linearly with age, oligodendrocytes accumulated sSNVs 81% faster than neurons and indels 28% slower than neurons. Correlation of mutations with single-nucleus RNA profiles and chromatin accessibility from the same brains revealed that oligodendrocyte mutations are enriched in inactive genomic regions and are distributed across the genome similarly to mutations in brain cancers. In contrast, neuronal mutations are enriched in open, transcriptionally active chromatin. These stark differences suggest an assortment of active mutagenic processes in oligodendrocytes and neurons.

CSF1R-mediated myeloid cell depletion shifts the ratio of motor cortical excitatory to inhibitory neurons in a multiple system atrophy model

Motor cortical circuit functions depend on the coordinated fine-tuning of two functionally diverse neuronal populations: glutamatergic pyramidal neurons providing synaptic excitation and GABAergic interneurons adjusting the response of pyramidal neurons through synaptic inhibition. Microglia are brain resident macrophages which dynamically refine cortical circuits by monitoring perineuronal extracellular matrix and remodelling synapses. Previously, we showed that colony-stimulating factor 1 receptor (CSF1R)-mediated myeloid cell depletion extended the lifespan, but impaired motor functions of MBP29 mice, a mouse model for multiple system atrophy. In order to better understand the mechanisms underlying these motor deficits we characterized the microglial involvement in the cortical balance of GABAergic interneurons and glutamatergic pyramidal neurons in 4-months-old MBP29 mice following CSF1R inhibition for 12 weeks. Lack of myeloid cells resulted in a decreased number of COUP TF1 interacting protein 2-positive (CTIP2+) layer V pyramidal neurons, however in a proportional increase of calretinin-positive GABAergic interneurons in MBP29 mice. While myeloid cell depletion did not alter the expression of important presynaptic and postsynaptic proteins, the loss of cortical perineuronal net area was attenuated by CSF1R inhibition in MBP29 mice. These cortical changes may restrict synaptic plasticity and potentially modify parvalbumin-positive perisomatic input. Collectively, this study suggests, that the lack of myeloid cells shifts the neuronal balance toward an increased inhibitory connectivity in the motor cortex of MBP29 mice thereby potentially deteriorating motor functions.

Identification of metabolic pathways and key genes associated with atypical parkinsonism using a systems biology approach

Atypical parkinsonism (AP) is a group of complex neurodegenerative disorders with marked clinical and pathophysiological heterogeneity. The use of systems biology tools may contribute to the characterization of hub-bottleneck genes, and the identification of its biological pathways to broaden the understanding of the bases of these disorders. A systematic search was performed on the DisGeNET database, which integrates data from expert curated repositories, GWAS catalogues, animal models and the scientific literature. The tools STRING 11.0 and Cytoscape 3.8.2 were used for analysis of protein-protein interaction (PPI) network. The PPI network topography analyses were performed using the CytoHubba 0.1 plugin for Cytoscape. The hub and bottleneck genes were inserted into 4 different sets on the InteractiveVenn. Additional functional enrichment analyses were performed to identify Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways and gene ontology for a described set of genes. The systematic search in the DisGeNET database identified 485 genes involved with Atypical Parkinsonism. Superimposing these genes, we detected a total of 31 hub-bottleneck genes. Moreover, our functional enrichment analyses demonstrated the involvement of these hub-bottleneck genes in 3 major KEGG pathways. We identified 31 highly interconnected hub-bottleneck genes through a systems biology approach, which may play a key role in the pathogenesis of atypical parkinsonism. The functional enrichment analyses showed that these genes are involved in several biological processes and pathways, such as the glial cell development, glial cell activation and cognition, pathways were related to Alzheimer disease and Parkinson disease. As a hypothesis, we highlight as possible key genes for AP the MAPT (microtubule associated protein tau), APOE (apolipoprotein E), SNCA (synuclein alpha) and APP (amyloid beta precursor protein) genes.

The potential of phosphorylated α-synuclein as a biomarker for the diagnosis and monitoring of multiple system atrophy

INTRODUCTION

Multiple system atrophy (MSA) is a rapidly progressive neurodegenerative disorder characterized by the presence of glial cytoplasmic inclusions (GCIs) containing aggregated α-synuclein (α-Syn). Accurate diagnosis and monitoring of MSA present significant challenges, which can lead to potential misdiagnosis and inappropriate treatment. Biomarkers play a crucial role in improving the accuracy of MSA diagnosis, and phosphorylated α-synuclein (p-syn) has emerged as a promising biomarker for aiding in diagnosis and disease monitoring.

METHODS

A literature search was conducted on PubMed, Scopus, and Google Scholar using specific keywords and MeSH terms without imposing a time limit. Inclusion criteria comprised various study designs including experimental studies, case-control studies, and cohort studies published only in English, while conference abstracts and unpublished sources were excluded.

RESULTS

Increased levels of p-syn have been observed in various samples from MSA patients, such as red blood cells, cerebrospinal fluid, oral mucosal cells, skin, and colon biopsies, highlighting their diagnostic potential. The α-Syn RT-QuIC assay has shown sensitivity in diagnosing MSA and tracking its progression. Meta-analyses and multicenter investigations have confirmed the diagnostic value of p-syn in cerebrospinal fluid, demonstrating high specificity and sensitivity in distinguishing MSA from other neurodegenerative diseases. Moreover, combining p-syn with other biomarkers has further improved the diagnostic accuracy of MSA.

CONCLUSION

The p-syn stands out as a promising biomarker for MSA. It is found in oligodendrocytes and shows a correlation with disease severity and progression. However, further research and validation studies are necessary to establish p-syn as a reliable biomarker for MSA. If proven, p-syn could significantly contribute to early diagnosis, disease monitoring, and assessing treatment response.

Apolipoprotein E Gene in α-Synucleinopathies: A Narrative Review

In this narrative review, we delved into the intricate interplay between Apolipoprotein E (APOE) alleles (typically associated with Alzheimer's disease-AD) and alpha-synucleinopathies (aS-pathies), involving Parkinson's disease (PD), Parkinson's disease dementia (PDD), dementia with Lewy bodies (DLB), and multiple-system atrophy (MSA). First, in-vitro, animal, and human-based data on the exacerbating effect of APOE4 on LB pathology were summarized. We found robust evidence that APOE4 carriage constitutes a risk factor for PDD-APOE2, and APOE3 may not alter the risk of developing PDD. We confirmed that APOE4 copies confer an increased hazard towards DLB, as well. Again APOE2 and APOE3 appear unrelated to the risk of conversion. Of note, in individuals with DLB APOE4, carriage appears to be intermediately prevalent between AD and PDD-PD (AD > DLB > PDD > PD). Less consistency existed when it came to PD; APOE-PD associations tended to be markedly modified by ethnicity. Finally, we failed to establish an association between the APOE gene and MSA. Phenotypic associations (age of disease onset, survival, cognitive-neuropsychiatric- motor-, and sleep-related manifestations) between APOE alleles, and each of the aforementioned conditions were also outlined. Finally, a synopsis of literature gaps was provided followed by suggestions for future research.

Clinical Trial-Ready Patient Cohorts for Multiple System Atrophy: Coupling Biospecimen and iPSC Banking to Longitudinal Deep-Phenotyping

Multiple system atrophy (MSA) is a fatal neurodegenerative disease of unknown etiology characterized by widespread aggregation of the protein alpha-synuclein in neurons and glia. Its orphan status, biological relationship to Parkinson's disease (PD), and rapid progression have sparked interest in drug development. One significant obstacle to therapeutics is disease heterogeneity. Here, we share our process of developing a clinical trial-ready cohort of MSA patients (69 patients in 2 years) within an outpatient clinical setting, and recruiting 20 of these patients into a longitudinal "n-of-few" clinical trial paradigm. First, we deeply phenotype our patients with clinical scales (UMSARS, BARS, MoCA, NMSS, and UPSIT) and tests designed to establish early differential diagnosis (including volumetric MRI, FDG-PET, MIBG scan, polysomnography, genetic testing, autonomic function tests, skin biopsy) or disease activity (PBR06-TSPO). Second, we longitudinally collect biospecimens (blood, CSF, stool) and clinical, biometric, and imaging data to generate antecedent disease-progression scores. Third, in our Mass General Brigham SCiN study (stem cells in neurodegeneration), we generate induced pluripotent stem cell (iPSC) models from our patients, matched to biospecimens, including postmortem brain. We present 38 iPSC lines derived from MSA patients and relevant disease controls (spinocerebellar ataxia and PD, including alpha-synuclein triplication cases), 22 matched to whole-genome sequenced postmortem brain. iPSC models may facilitate matching patients to appropriate therapies, particularly in heterogeneous diseases for which patient-specific biology may elude animal models. We anticipate that deeply phenotyped and genotyped patient cohorts matched to cellular models will increase the likelihood of success in clinical trials for MSA.

Neuropathology of Multiple System Atrophy, a Glioneuronal Degenerative Disease

Multiple system atrophy (MSA) is a fatal disease characterized pathologically by the widespread occurrence of aggregated α-synuclein in the oligodendrocytes referred to as glial cytoplasmic inclusions (GCIs). α-Synuclein aggregates are also found in the oligodendroglial nuclei and neuronal cytoplasm and nuclei. It is uncertain whether the primary source of α-synuclein in GCIs is originated from neurons or oligodendrocytes. Accumulating evidence suggests that there are two degenerative processes in this disease. One possibility is that numerous GCIs are associated with the impairment of oligo-myelin-axon-neuron complex, and the other is that neuronal inclusion pathology is also a primary event from the early stage. Both oligodendrocytes and neurons may be primarily affected in MSA, and the damage of one cell type contributes to the degeneration of the other. Vesicle-mediated transport plays a key role in the nuclear translocation of α-synuclein as well as in the formation of glial and neuronal α-synuclein inclusions. Recent studies have shown that impairment of autophagy can occur along with or as a result of α-synuclein accumulation in the brain of MSA and Lewy body disease. Activated autophagy may be implicated in the therapeutic approach for α-synucleinopathies.

IFNγ drives neuroinflammation, demyelination, and neurodegeneration in a mouse model of multiple system atrophy

Multiple system atrophy (MSA) is a rare and fatal synucleinopathy characterized by insoluble alpha-synuclein (α-syn) cytoplasmic inclusions located within oligodendroglia. Neuroinflammation, demyelination, and neurodegeneration are correlated with areas of glia cytoplasmic inclusions (GCI) pathology, however it is not known what specifically drives disease pathogenesis. Recent studies have shown that disease pathologies found in post-mortem tissue from MSA patients can be modeled in rodents via a modified AAV overexpressing α-syn, Olig001-SYN, which has a 95% tropism for oligodendrocytes. In the Olig001-SYN mouse model, CD4+ T cells have been shown to drive neuroinflammation and demyelination, however the mechanism by which this occurs remains unclear. In this study we use genetic and pharmacological approaches in the Olig001-SYN model of MSA to show that the pro-inflammatory cytokine interferon gamma (IFNγ) drives neuroinflammation, demyelination, and neurodegeneration. Furthermore, using an IFNγ reporter mouse, we found that infiltrating CD4+ T cells were the primary producers of IFNγ in response to α-syn overexpression in oligodendrocytes. Results from these studies indicate that IFNγ expression from CD4+ T cells drives α-syn-mediated neuroinflammation, demyelination, and neurodegeneration. These results indicate that targeting IFNγ expression may be a potential disease modifying therapeutic strategy for MSA.

Comparative Study between the Diagnostic Effectiveness of Brain SPECT with [123I]Ioflupane and [123I]MIBG Scintigraphy in Multiple System Atrophy

BACKGROUND

Multiple system atrophy (MSA) is a neurodegenerative disease. It has a fast progression, so early diagnosis is decisive. Two functional imaging tests can be involved in its diagnosis: [123I]Ioflupane SPECT and [123I]MIBG scintigraphy. Our aim is to comparatively analyze the diagnostic performance of both techniques.

METHODS

46 patients (24 males and 22 females) with MSA underwent [123I]Ioflupane SPECT and [123I]MIBG scintigraphy. In each of these techniques, qualitative assessment was compared with quantitative assessment.

RESULTS

SPECT visual assessment was positive in 93.5% of subjects (S = 95.24%; PPV = 93.02%). A cut-off of 1.363 was established for overall S/O index (S = 85.7%, E = 100%). Visual assessment of scintigraphy was positive in 73.1% (S = 78.57%, PPV = 94.29%). For the delayed heart/medistinum ratio (HMR) a cut-off of 1.43 (S = 85.3, E = 100%) was obtained. For each unit increase in delayed HMR, the suspicion of MSA increased by 1.58 (OR = 1.58, p < 0.05). The quantitative assessment showed an association with the visual assessment for each technique (p < 0.05).

CONCLUSIONS

Both tests are useful in MSA diagnosis. Comparatively, we did not observe a clear superiority of either. Striatal and myocardial deterioration do not evolve in parallel. Qualitative assessment is crucial in both techniques, together with the support of quantitative analysis. Delayed HMR shows a direct relationship with the risk of MSA.

An Update on Parkinson's Disease and its Neurodegenerative Counterparts

INTRODUCTION

Neurodegenerative disorders are a group of diseases that cause nerve cell degeneration in the brain, resulting in a variety of symptoms and are not treatable with drugs. Parkinson's disease (PD), prion disease, motor neuron disease (MND), Huntington's disease (HD), spinal cerebral dyskinesia (SCA), spinal muscle atrophy (SMA), multiple system atrophy, Alzheimer's disease (AD), spinocerebellar ataxia (SCA) (ALS), pantothenate kinase-related neurodegeneration, and TDP-43 protein disorder are examples of neurodegenerative diseases. Dementia is caused by the loss of brain and spinal cord nerve cells in neurodegenerative diseases.

BACKGROUND

Even though environmental and genetic predispositions have also been involved in the process, redox metal abuse plays a crucial role in neurodegeneration since the preponderance of symptoms originates from abnormal metal metabolism.

METHOD

Hence, this review investigates several neurodegenerative diseases that may occur symptoms similar to Parkinson's disease to understand the differences and similarities between Parkinson's disease and other neurodegenerative disorders based on reviewing previously published papers.

RESULTS

Based on the findings, the aggregation of alpha-synuclein occurs in Parkinson's disease, multiple system atrophy, and dementia with Lewy bodies. Other neurodegenerative diseases occur with different protein aggregation or mutations.

CONCLUSION

We can conclude that Parkinson's disease, Multiple system atrophy, and Dementia with Lewy bodies are closely related. Therefore, researchers must distinguish among the three diseases to avoid misdiagnosis of Multiple System Atrophy and Dementia with Lewy bodies with Parkinson's disease symptoms.

Pharmacological inhibition of FABP7 by MF 6 counteracts cerebellum dysfunction in an experimental multiple system atrophy mouse model

Multiple system atrophy (MSA) is a rare, fatal neurodegenerative disease characterized by the accumulation of misfolded α-synuclein (αSyn) in glial cells, leading to the formation of glial cytoplasmic inclusions (GCI). We previous found that glial fatty acid-binding protein 7 (FABP7) played a crucial role in alpha-synuclein (αSyn) aggregation and toxicity in oligodendrocytes, inhibition of FABP7 by a specific inhibitor MF 6 reduced αSyn aggregation and enhanced cell viability in cultured cell lines and mouse oligodendrocyte progenitor cells. In this study we investigated whether MF 6 ameliorated αSyn-associated pathological processes in PLP-hαSyn transgenic mice (PLP-αSyn mice), a wildly used MSA mouse model with overexpressing αSyn in oligodendroglia under the proteolipid protein (PLP) promoter. PLP-αSyn mice were orally administered MF6 (0.1, 1 mg ·kg-1 ·d-1) for 32 days starting from the age of 6 months. We showed that oral administration of MF 6 significantly improved motor function assessed in a pole test, and reduced αSyn aggregation levels in both cerebellum and basal ganglia of PLP-αSyn mice. Moreover, MF 6 administration decreased oxidative stress and inflammation levels, and improved myelin levels and Purkinje neuron morphology in the cerebellum. By using mouse brain tissue slices and αSyn aggregates-treated KG-1C cells, we demonstrated that MF 6 reduced αSyn propagation to Purkinje neurons and oligodendrocytes through regulating endocytosis. Overall, these results suggest that MF 6 improves cerebellar functions in MSA by inhibiting αSyn aggregation and propagation. We conclude that MF 6 is a promising compound that warrants further development for the treatment of MSA.

Data-Driven Subtypes of Multiple System Atrophy and Their Implications for Prognosis

Background

While multiple system atrophy (MSA) presents with high heterogeneous motor and nonmotor symptoms, the associations between clinical phenotypes and prognosis are unclear.

Objective

We aimed to evaluate clinical phenotypes of MSA using data-driven approach and measure the impact of phenotypes on survival and bedbound status.

Methods

193 MSA patients were recruited from Xuanwu Hospital Capital Medical University, whose history, motor and non-motor symptoms were examined using cluster analysis. Ninety-five participants were followed-up via telephone after a mean of 31.87 months. We employed Kaplan- Meier analysis to examine survival and performed Cox and logistic regression analyses to identify factors associated with survival and bedbound status.

Results

We identified four clinical profiles of MSA: cerebellar symptom-dominant, sleep and mood disorder-dominant, rigid akinetic-dominant, and malignant diffuse. The overall median survival was 7.75 years (95% CI 7.19-8.31). After adjusting for years from symptom onset to diagnosis, age and sex, patients in the malignant diffuse and rigid akinetic-dominant clusters had greater risk of death than sleep and mood disorder-dominant cluster. Furthermore, patients in the malignant diffuse and rigid akinetic-dominant clusters had higher risk of being bedbound than cerebellar symptom-dominant cluster.

Conclusions

The malignant diffuse and sleep and mood disorder-dominant were identified besides the two classical subtypes, parkinsonism, and cerebellar symptom-variant. Patients with rigid-akinetic motor profiles have a worse prognosis than cerebellar symptom-dominant profiles in general. Diffuse symptoms, especially postural instability, and cognitive alterations at diagnosis, indicate rapid functional loss and disease progression. The different profiles and prognoses might indicate varied underlying pathological mechanisms.

Follow-Up Findings in Multiple System Atrophy from [123I]Ioflupane Single-Photon Emission Computed Tomography (SPECT): A Prospective Study

BACKGROUND

Multiple system atrophy (MSA) is subdivided into two types: MSA-P (parkinsonian) and MSA-C (cerebellar). Brain SPECT allows for the detection of nigrostriatal involvement, even in the early stages. To date, the scientific literature does not show a consensus on how to follow-up MSA, especially MSA-C. Our aim was to analyze the diagnostic effectiveness of repeat [123I]Ioflupane SPECT for the follow-up of MSA.

METHODS

A longitudinal observational study on 22 MSA patients (11 males and 11 females).

RESULTS

Significant changes were obtained in the quantitative SPECT assessments in the three Striatum/Occipital indices. The qualitative SPECT diagnosis did not show differences between the initial and evolving SPECT, but the neurologist's clinical suspicion did. Our results showed a brain deterioration of around 31% at 12 months, this being the optimal cut-off for differentiating a diseased subject (capable of solving diagnostic error rate). Previous imaging tests were inconclusive, as they showed less deterioration in the SPECT and quantitative assessments with respect to the group of confirmed patients. Repeated SPECT increased the diagnostic sensitivity (50% vs. 75%) and positive predictive value (72.73% vs. 77%). In addition, repeated SPECT proved decisive in the diagnosis of initial inconclusive cases.

CONCLUSION

Repeat SPECT at 12 months proves useful in the diagnosis and follow-up of MSA.

Mild cognitive impairment in multiple system atrophy: a brain network disorder

Cognitive impairment (CI), previously considered as a non-supporting feature of multiple system atrophy (MSA), according to the second consensus criteria, is not uncommon in this neurodegenerative disorder that is clinically characterized by a variable combination of autonomic failure, levodopa-unresponsive parkinsonism, motor and cerebellar signs. Mild cognitive impairment (MCI), a risk factor for dementia, has been reported in up to 44% of MSA patients, with predominant impairment of executive functions/attention, visuospatial and verbal deficits, and a variety of non-cognitive and neuropsychiatric symptoms. Despite changing concept of CI in this synucleinopathy, the underlying pathophysiological mechanisms remain controversial. Recent neuroimaging studies revealed volume reduction in the left temporal gyrus, and in the dopaminergic nucleus accumbens, while other morphometric studies did not find any gray matter atrophy, in particular in the frontal cortex. Functional analyses detected decreased functional connectivity in the left parietal lobe, bilateral cuneus, left precuneus, limbic structures, and cerebello-cerebral circuit, suggesting that structural and functional changes in the subcortical limbic structures and disrupted cerebello-cerebral networks may be associated with early cognitive decline in MSA. Whereas moderate to severe CI in MSA in addition to prefrontal-striatal degeneration is frequently associated with cortical Alzheimer and Lewy co-pathologies, neuropathological studies of the MCI stage of MSA are unfortunately not available. In view of the limited structural and functional findings in MSA cases with MCI, further neuroimaging and neuropathological studies are warranted in order to better elucidate its pathophysiological mechanisms and to develop validated biomarkers as basis for early diagnosis and future adequate treatment modalities in order to prevent progression of this debilitating disorder.

The characteristics and alteration of peripheral immune function in patients with multiple system atrophy

Objective

Multiple system atrophy (MSA) is a degenerative disease. Immune dysfunction found to play a crucial role in the pathogenesis of this disease in the literature, while the characteristics of peripheral immune function remain unclear. This study aimed to investigate the characteristics and alterations of peripheral immune function in patients with MSA.

Methods

A case-control study was conducted between January 2021 to December 2022 at SanBo Brain Hospital, Capital Medical University, Beijing, China. A total of 74 participants were recruited, including 47 MSA patients and 27 non-MSA participants. Peripheral blood samples were collected from each participant. A total of 29 types of immune cells were measured using the flow cytometry analysis technology. Single-factor analysis and multiple-factor analysis (multiple linear regression models) were performed to determine the differences and risk factors in immune cells between the MSA and non-MSA groups.

Results

Alterations of the count or percentage of CD19+ B lymphocytes and CD3-CD56+ B lymphocytes in MSA patients were found in this study. The reductions of the count and percentage of CD19+ B lymphocytes were still robust after adjusting for variables of age, gender, body mass index, albumin, and hemoglobin. Furthermore, the reductions in the count and percentage of CD19+ B lymphocytes in the MSA patients were more significant in women and individuals aged 60 years old or above than in the non-MSA participants.

Conclusion

Our findings suggested that MSA patients may be influenced by B lymphocytes, particularly CD19+ cells. Therefore, the reductions in immune cells should be considered in the diagnosis and treatment of MSA. Further studies are warranted to confirm and expand upon these findings.

α-Synuclein pathology in post-mortem retina and optic nerve is specific for α-synucleinopathies

There is increasing interest in studying retinal biomarkers for various neurodegenerative diseases. Specific protein aggregates associated with neurodegenerative diseases are present in the retina and could be visualised in a non-invasive way. This study aims to assess the specificity and sensitivity of retinal α-synuclein aggregates in neuropathologically characterised α-synucleinopathies, other neurodegenerative diseases and non-neurological controls. Post-mortem eyes (N = 99) were collected prospectively through the Netherlands Brain Bank from donors with Parkinson's disease (and dementia), dementia with Lewy bodies, multiple system atrophy, Alzheimer's disease, other neurodegenerative diseases and non-neurological controls. Multiple retinal and optic nerve cross-sections were immunostained with anti-α-synuclein antibodies (LB509, KM51, and anti-pSer129) and assessed for aggregates and inclusions. α-Synuclein was observed as Lewy neurites in the retina and oligodendroglial cytoplasmic inclusions in the optic nerve and was highly associated with Lewy body disease (P < 0.001) and multiple system atrophy (P = 0.001). In all multiple system atrophy cases, the optic nerve showed oligodendroglial cytoplasmic inclusions, while retinal Lewy neurites were absent, despite coincidental brain Lewy pathology. With high specificity (97%) and sensitivity (82%), retinal/optic nerve α-synuclein differentiates primary α-synucleinopathies from other cases and controls. α-Synuclein pathology occurs specifically in the retina and optic nerve of primary α-synucleinopathies as opposed to other neurodegenerative diseases-with and without α-synuclein co-pathology-and controls. The absence of retinal Lewy neurites in multiple system atrophy could contribute to the development of an in vivo retinal biomarker that discriminates between Lewy body disease and multiple system atrophy.

Diagnostic Effectiveness of [123I]Ioflupane Single Photon Emission Computed Tomography (SPECT) in Multiple System Atrophy

BACKGROUND

Multiple system atrophy (MSA) is a rapidly progressive neurodegenerative disorder that has no curative treatment. Diagnosis is based on a set of criteria established by Gilman (1998 and 2008) and recently updated by Wenning (2022). We aim to determine the effectiveness of [¹²³I]Ioflupane SPECT in MSA, especially at the initial clinical suspicion.

METHODS

A cross-sectional study of patients at the initial clinical suspicion of MSA, referred for [¹²³I]Ioflupane SPECT.

RESULTS

Overall, 139 patients (68 men, 71 women) were included, 104 being MSA-probable and 35 MSA-possible. MRI was normal in 89.2%, while SPECT was positive in 78.45%. SPECT showed high sensitivity (82.46%) and positive predictive value (86.24), reaching maximum sensitivity in MSA-P (97.26%). Significant differences were found when relating both SPECT assessments in the healthy-sick and inconclusive-sick groups. We also found an association when relating SPECT to the subtype (MSA-C or MSA-P), as well as to the presence of parkinsonian symptoms. Lateralization of striatal involvement was detected (left side).

CONCLUSIONS

[¹²³I]Ioflupane SPECT is a useful and reliable tool for diagnosing MSA, with good effectiveness and accuracy. Qualitative assessment shows a clear superiority when distinguishing between the healthy-sick categories, as well as between the parkinsonian (MSA-P) and cerebellar (MSA-C) subtypes at initial clinical suspicion.

Migratory Response of Cells in Neurogenic Niches to Neuronal Death: The Onset of Harmonic Repair?

Harmonic mechanisms orchestrate neurogenesis in the healthy brain within specific neurogenic niches, which generate neurons from neural stem cells as a homeostatic mechanism. These newly generated neurons integrate into existing neuronal circuits to participate in different brain tasks. Despite the mechanisms that protect the mammalian brain, this organ is susceptible to many different types of damage that result in the loss of neuronal tissue and therefore in alterations in the functionality of the affected regions. Nevertheless, the mammalian brain has developed mechanisms to respond to these injuries, potentiating its capacity to generate new neurons from neural stem cells and altering the homeostatic processes that occur in neurogenic niches. These alterations may lead to the generation of new neurons within the damaged brain regions. Notwithstanding, the activation of these repair mechanisms, regeneration of neuronal tissue within brain injuries does not naturally occur. In this review, we discuss how the different neurogenic niches respond to different types of brain injuries, focusing on the capacity of the progenitors generated in these niches to migrate to the injured regions and activate repair mechanisms. We conclude that the search for pharmacological drugs that stimulate the migration of newly generated neurons to brain injuries may result in the development of therapies to repair the damaged brain tissue.

Role of Oligodendrocyte Lineage Cells in Multiple System Atrophy

Multiple system atrophy (MSA) is a debilitating movement disorder with unknown etiology. Patients present characteristic parkinsonism and/or cerebellar dysfunction in the clinical phase, resulting from progressive deterioration in the nigrostriatal and olivopontocerebellar regions. MSA patients have a prodromal phase subsequent to the insidious onset of neuropathology. Therefore, understanding the early pathological events is important in determining the pathogenesis, which will assist with developing disease-modifying therapy. Although the definite diagnosis of MSA relies on the positive post-mortem finding of oligodendroglial inclusions composed of α-synuclein, only recently has MSA been verified as an oligodendrogliopathy with secondary neuronal degeneration. We review up-to-date knowledge of human oligodendrocyte lineage cells and their association with α-synuclein, and discuss the postulated mechanisms of how oligodendrogliopathy develops, oligodendrocyte progenitor cells as the potential origins of the toxic seeds of α-synuclein, and the possible networks through which oligodendrogliopathy induces neuronal loss. Our insights will shed new light on the research directions for future MSA studies.

Review of Technological Challenges in Personalised Medicine and Early Diagnosis of Neurodegenerative Disorders

Neurodegenerative disorders are characterised by progressive neuron loss in specific brain areas. The most common are Alzheimer's disease and Parkinson's disease; in both cases, diagnosis is based on clinical tests with limited capability to discriminate between similar neurodegenerative disorders and detect the early stages of the disease. It is common that by the time a patient is diagnosed with the disease, the level of neurodegeneration is already severe. Thus, it is critical to find new diagnostic methods that allow earlier and more accurate disease detection. This study reviews the methods available for the clinical diagnosis of neurodegenerative diseases and potentially interesting new technologies. Neuroimaging techniques are the most widely used in clinical practice, and new techniques such as magnetic resonance imaging (MRI) and positron emission tomography (PET) have significantly improved the diagnosis quality. Identifying biomarkers in peripheral samples such as blood or cerebrospinal fluid is a major focus of the current research on neurodegenerative diseases. The discovery of good markers could allow preventive screening to identify early or asymptomatic stages of the neurodegenerative process. These methods, in combination with artificial intelligence, could contribute to the generation of predictive models that will help clinicians in the early diagnosis, stratification, and prognostic assessment of patients, leading to improvements in patient treatment and quality of life.

Development of PPARγ Agonists for the Treatment of Neuroinflammatory and Neurodegenerative Diseases: Leriglitazone as a Promising Candidate

Increasing evidence suggests that the peroxisome proliferator-activated receptor γ (PPARγ), a member of the nuclear receptor superfamily, plays an important role in physiological processes in the central nervous system (CNS) and is involved in cellular metabolism and repair. Cellular damage caused by acute brain injury and long-term neurodegenerative disorders is associated with alterations of these metabolic processes leading to mitochondrial dysfunction, oxidative stress, and neuroinflammation. PPARγ agonists have demonstrated the potential to be effective treatments for CNS diseases in preclinical models, but to date, most drugs have failed to show efficacy in clinical trials of neurodegenerative diseases including amyotrophic lateral sclerosis, Parkinson's disease, and Alzheimer's disease. The most likely explanation for this lack of efficacy is the insufficient brain exposure of these PPARγ agonists. Leriglitazone is a novel, blood-brain barrier (BBB)-penetrant PPARγ agonist that is being developed to treat CNS diseases. Here, we review the main roles of PPARγ in physiology and pathophysiology in the CNS, describe the mechanism of action of PPARγ agonists, and discuss the evidence supporting the use of leriglitazone to treat CNS diseases.

Exploring the mechanism of astragalus membranaceus in the treatment of multiple system atrophy based on network pharmacology and molecular docking

Multiple system atrophy (MSA) is a fatal neurodegenerative disease, it causes functional degradation of multiple organs and systems throughout the body. Astragalus membranaceus (AM), a well-known traditional Chinese medicine, has been used to improve muscle wasting-related disorders for a long history. In this study, we used network pharmacology and molecular docking to predict the mechanism underlying AM for the treatment of MSA. We screened the active compounds of AM and its related targets, as well as the target proteins of MSA. We made a Venn diagram to obtain the intersecting targets and then constructed a protein-protein interaction network to find the core targets and build an active ingredient-target network map. After subjecting the intersecting targets to gene ontology and Kyoto encyclopedia of genes and genomes analysis, the binding ability of core compounds and core target proteins were validated by molecular docking. A total of 20 eligible compounds and 274 intersecting targets were obtained. The core components of treatment are quercetin, kaempferol, and isorhamnetin, and the core targets are TP53, RELA, and TNF. The main biological processes are related to cellular responses and regulation. Molecular functions are mainly associated with apoptosis, inflammation, and tumorigenesis. Molecular docking results show good and standard binding abilities. This study illustrates that AM treats MSA through multiple targets and pathways, and provides a reference for subsequent research.

Phosphorylated tau in the retina correlates with tau pathology in the brain in Alzheimer's disease and primary tauopathies

The retina is a potential source of biomarkers for the detection of neurodegenerative diseases. Accumulation of phosphorylated tau (p-tau) in the brain is a pathological feature characteristic for Alzheimer's disease (AD) and primary tauopathies. In this study the presence of p-tau in the retina in relation to tau pathology in the brain was assessed. Post-mortem eyes and brains were collected through the Netherlands Brain Bank from donors with AD (n = 17), primary tauopathies (n = 8), α-synucleinopathies (n = 13), other neurodegenerative diseases including non-tau frontotemporal lobar degeneration (FTLD) (n = 9), and controls (n = 15). Retina cross-sections were assessed by immunohistochemistry using antibodies directed against total tau (HT7), 3R and 4R tau isoforms (RD3, RD4), and phospho-epitopes Ser202/Thr205 (AT8), Thr217 (anti-T217), Thr212/Ser214 (AT100), Thr181 (AT270), Ser396 (anti-pS396) and Ser422 (anti-pS422). Retinal tau load was compared to p-tau Ser202/Thr205 and p-tau Thr217 load in various brain regions. Total tau, 3R and 4R tau isoforms were most prominently present in the inner plexiform layer (IPL) and outer plexiform layer (OPL) of the retina and were detected in all cases and controls as a diffuse and somatodendritic signal. Total tau, p-tau Ser202/Thr205 and p-tau Thr217 was observed in amacrine and horizontal cells of the inner nuclear layer (INL). Various antibodies directed against phospho-epitopes of tau showed immunoreactivity in the IPL, OPL, and INL. P-tau Ser202/Thr205 and Thr217 showed significant discrimination between AD and other tauopathies, and non-tauopathy cases including controls. Whilst immunopositivity was observed for p-tau Thr212/Ser214, Thr181 and Ser396, there were no group differences. P-tau Ser422 did not show any immunoreactivity in the retina. The presence of retinal p-tau Ser202/Thr205 and Thr217 correlated with Braak stage for NFTs and with the presence of p-tau Ser202/Thr205 in hippocampus and cortical brain regions. Depending on the phospho-epitope, p-tau in the retina is a potential biomarker for AD and primary tauopathies.

Lifelong constipation in Parkinson's disease and other clinically defined alpha-synucleinopathies: A population-based study in Southeast Minnesota

INTRODUCTION

Epidemiological studies show correlations between constipation and development of Parkinson's disease (PD); however, few studies have explored the association between constipation and dementia with Lewy bodies (DLB), Parkinson's disease dementia (PDD), and multiple system atrophy (MSA). We sought to explore the lifelong association of constipation and PD, DLB, PDD, and MSA (α-Synucleinopathies), compared to age- and sex-matched controls.

METHODS

Using the Rochester Epidemiology Project (REP), we established an incident cohort of clinically defined α-synucleinopathies. A movement-disorder specialist reviewed all medical charts to establish clinical diagnoses.

RESULTS

We identified 453 incident cases of clinically diagnosed α-synucleinopathies and an identical number of age- and sex-matched controls in Olmsted County (MN), 1991-2010. There were 303 cases of PD; 80, DLB; 54, PDD; and 16, MSA. Approximately 50% of α-synucleinopathies of all types reported constipation, compared to 27% in controls. The earliest pre-motor onset constipation was in DLB (median, 3.76 years prior to α-synucleinopathies motor-symptom onset); latest onset post-motor constipation was in PD (median, 5.15 years after motor-symptom onset). PD also had the highest longstanding constipation rate (18.2%). All α-synucleinopathies had higher odds of constipation compared to controls, except for MSA (p = 0.09), likely due to a limited sample size.

CONCLUSION

PD, DLB, and PDD had higher odds of constipation compared to controls; PD had the most widespread onset of lifelong constipation, both longstanding and pre- or post-motor onset symptoms. Our results indicate that constipation rates do not differ among α-synucleinopathies but do differ in terms of temporal onset compared to disease onset.

Morphological differences between the two major subtypes of multiple system atrophy with cognitive impairment

OBJECTIVE

To compare the neuropathology between two types of multiple system atrophy - parkinsonism-predominant (MSA-P) and cerebellar ataxia-predominant (MSA-C) with cognitive impairment.

MATERIAL & METHODS

35 cases of MSA-P (mean age at death 60.5 ± 7.8 years) and 15 cases of MSA-C (mean age at death 61.3 ± 6.8 years), 35.% of which associated with mild to moderate cognitive impairment and one with severe dementia, were examined neuropathologically with semiquantitative evaluation of both α-synuclein and Alzheimer pathologies, including cerebral amyloid angiopathy (CAA) and other co-pathologies.

RESULTS

While the mean age at death of both MSA subgroups was similar, the age at onset and duration of disease were slightly higher in the MSA-C group. In line with the classification, the αSyn pathology glial and neuronal inclusions in both the cortex and brainstem were significantly higher in the MSA-P group. With regard to the Alzheimer disease pathology, tau load in cases with mild to moderate cognitive impairment was slightly but not significantly higher in the MSA-P group, one with severe dementia showing fully developed Alzheimer co-pathology, while the amyloid-β (Aβ) load including the CAA was higher in the MSA-C group. The presence of Lewy co-pathology in this series (20%), being similar to that of other MSA cohorts, was more frequent in MSA cases with mild to severe cognitive impairment, but did not differ between the two subgroups and seems not essentially important for MCI in MSA.

CONCLUSIONS

In agreement with previous clinical studies that reported more severe cognitive dysfunction in patients with MSA-P, the present neuropathological study showed increased tau pathology in MSA-P and one with severe Alzheimer co-pathology, but only slightly increased amyloid pathology in the MSA-C group. Lewy co-pathology was more frequent in MSA-P cases with cognitive decline. In view of the limited data about the pathobiological basis of cognitive impairment in MSA, further studies to elucidate the differences between the two phenotypes are urgently needed.

The Peripheral Immune Traits Changed in Patients with Multiple System Atrophy

A growing body of evidence suggests immune involvement in the pathology of multiple system atrophy (MSA). Research on detailed peripheral immune indices, however, is relatively sparse, and is one of the intriguing aspects of MSA yet to be elucidated. A total of 26 MSA patients and 56 age-and sex-matched healthy controls (HC) were enrolled in the current case-control study to delineate the peripheral immune traits of MSA patients. The ratio of CD4⁺/CD8⁺ T cells, natural killer cells, CD28 expression on both CD4⁺ T cells and CD8⁺ T cells increased in MSA patients compared to HC, but CD8⁺ T cells and active marker (HLA-DR) expression on total T cells decreased (p < 0.05). This study sheds light on the dysregulation of cellular immunity in MSA, pointing to future mechanistic research.

Gene Set Enrichment Analysis and Genetic Experiment Reveal Changes in Cell Signaling Pathways Induced by α-Synuclein Overexpression

Abnormal accumulation of alpha synuclein (α-Syn) in sporadic and familial Parkinson's disease (PD) may be a key step in its pathogenesis. In this study, the expression matrix of the GSE95427 dataset after α-Syn overexpression in human glioma cell line H4 was obtained from the GEO database. We used the Gene Set Enrichment Analysis (GSEA) method to reanalyze this dataset to evaluate the possible functions of α-Syn. The results showed that the tumor necrosis factor alpha (TNF-α) signal was significantly activated in α-Syn-overexpressing cells, and oxidative phosphorylation signal, extracellular matrix signal, cell cycle related signal and fatty acid metabolism signal were significantly inhibited. Moreover, we employed the α-Syn-expressing transgenic Drosophila model of Parkinson's disease and knocked-down eiger, a TNF superfamily ligand homologue, indicating that the TNF-α pathway plays a role in the common pathogenesis of synucleinopathies. Our analysis based on GSEA data provides more clues for a better understanding of α-Syn function.

Contrasting patterns of somatic mutations in neurons and glia reveal differential predisposition to disease in the aging human brain

Characterizing the mechanisms of somatic mutations in the brain is important for understanding aging and disease, but little is known about the mutational patterns of different cell types. We performed whole-genome sequencing of 71 oligodendrocytes and 51 neurons from neurotypical individuals (0.4 to 104 years old) and identified >67,000 somatic single nucleotide variants (sSNVs) and small insertions and deletions (indels). While both cell types accumulate mutations with age, oligodendrocytes accumulate sSNVs 69% faster than neurons (27/year versus 16/year) whereas indels accumulate 42% slower (1.8/year versus 3.1/year). Correlation with single-cell RNA and chromatin accessibility from the same brains revealed that oligodendrocyte mutations are enriched in inactive genomic regions and are distributed similarly to mutations in brain cancers. In contrast, neuronal mutations are enriched in open, transcriptionally active chromatin. These patterns highlight differences in the mutagenic processes in glia and neurons and suggest cell type-specific, age-related contributions to neurodegeneration and oncogenesis.

Comparison of the second consensus statement with the movement disorder society criteria for multiple system atrophy: A single-center analysis

INTRODUCTION

This study aimed at comparing the differences between the second consensus statement and Movement Disorder Society (MDS) criteria for Multiple System Atrophy (MSA) in a single Chinese cohort.

METHODS

We retrospectively reviewed 73 patients with MSA over the past five years. They were categorized as patients with probable and possible MSA according to the second consensus statement in addition to clinically established and clinically probable MSA according to the MDS criteria. The core clinical, supportive clinical, and imaging features were analyzed and compared between the two MSA subtypes.

RESULTS

A total of 40 patients with MSA-P and 33 patients with MSA-C were included in this study. Approximately 78.7% of the category of probable patients in the second consensus statement can be categorized as clinically established MSA in the MDS criteria and five patients with non-supporting features in the second consensus statement criteria can be diagnosed as clinically probable MSA in the MDS criteria. "Rapid progression" and "moderate to severe postural instability" within three years of motor onset dominated among the supportive features. Approximately 78.9% of patients possessed at least one imaging marker with predominant signal decrease of putamen on iron-sensitive sequences (38.0% of patients). Twenty-two patients could not be diagnosed as clinically established MSA mainly due to the lack of supportive or imaging features.

CONCLUSIONS

A high degree of agreement was noticed between the two criteria sets. The supportive and imaging features played important role in the diagnosis of MSA and affected the diagnostic level in the current criteria.

Multiple System Atrophy Caregivers' Experience: A Mixed Methods Study

BACKGROUND

Multiple system atrophy (MSA) is a rare Parkinson-plus syndrome with rapid progression and a high symptom burden. The experience of caregivers of people with MSA has not been closely examined. We therefore sought to document the impact of MSA on caregivers using a mixed methods approach.

METHODS

Patients and caregivers were recruited from a movement disorders program in Edmonton, Canada. Participants completed the following survey instruments based on their own or their loved one's symptoms: 36-Item Short-Form Health Survey (SF-36), Multiple System Atrophy health-related Quality of Life scale (MSA-QoL), and Hospital Anxiety and Depression Scale (HADS). Caregivers also completed the Zarit Burden Interview and HADS based on their own experience. Qualitative data were obtained through semi-structured interviews.

RESULTS

Nine people with MSA (PwMSA) (age range: 48-78 years) and 11 caregivers (49-76 years) participated. All completed surveys; 7 PwMSA and 10 caregivers were interviewed. Eight PwMSA had the parkinsonian type of MSA (MSA-P) and one a mixed type. Caregivers had on average mild-moderate caregiver burden and mild anxiety. Caregiver burden and anxiety were correlated. Qualitative subthemes under the caregiving theme included keeping the patient safe, caregivers' own health, and communication symptoms cause frustration. The rapid progression of illness was bewildering to caregivers and increased their workload. Public home care services were invaluable to caregivers' maintaining their loved ones at home. Caregivers were inventive in finding sources of hope and quality of life for their loved ones.

CONCLUSION

Publicly funded home care was essential for caregivers of PwMSA in this study. Caregiver support is needed to provide this unrecognized workforce with information and resources to face this challenging condition.

Pathomechanisms of depression in multiple system atrophy

Multiple system atrophy (MSA) is a rapidly progressing neurodegenerative disorder of uncertain etiology that is characterized by various combinations of Parkinsonism, autonomic, cerebellar and motor dysfunctions, with poor prognosis. Little is known about modifiable factors, such as depression, that has negative effects on quality of life in MSA. Depression, with an estimated prevalence of about 43%, is among the most common neuropsychiatric disorders in MSA similar to other atypical Parkinsonian disorders, the frequency of which is associated with increased disease progression, disease severity and autonomic dysfunctions. Depression in MSA, like in Parkinson disease, has been related to a variety of pathogenic mechanisms associated with the underlying neurodegenerative process, such as involvement of serotonergic neuron groups in the brainstem, prefrontal cortical dysfunctions, and altered functional fronto-temporal-thalamic connectivities with disturbances of mood related and other essential resting-state brain networks. The pathophysiology and pathogenesis of depression in MSA, as in other degenerative movement disorders, are complex and deserve further elucidation as a basis for adequate treatment to improve the quality of life in this fatal disease.

Functions and dysfunctions of oligodendrocytes in neurodegenerative diseases

Neurodegenerative diseases (NDDs) are characterized by the progressive loss of selectively vulnerable populations of neurons, which is responsible for the clinical symptoms. Although degeneration of neurons is a prominent feature that undoubtedly contributes to and defines NDD pathology, it is now clear that neuronal cell death is by no means mediated solely by cell-autonomous mechanisms. Oligodendrocytes (OLs), the myelinating cells of the central nervous system (CNS), enable rapid transmission of electrical signals and provide metabolic and trophic support to neurons. Recent evidence suggests that OLs and their progenitor population play a role in the onset and progression of NDDs. In this review, we discuss emerging evidence suggesting a role of OL lineage cells in the pathogenesis of age-related NDDs. We start with multiple system atrophy, an NDD with a well-known oligodendroglial pathology, and then discuss Alzheimer's disease (AD) and Parkinson's disease (PD), NDDs which have been thought of as neuronal origins. Understanding the functions and dysfunctions of OLs might lead to the advent of disease-modifying strategies against NDDs.

Glutathione Depletion and MicroRNA Dysregulation in Multiple System Atrophy: A Review

Multiple system atrophy (MSA) is a rare neurodegenerative disease characterized by parkinsonism, cerebellar impairment, and autonomic failure. Although the causes of MSA onset and progression remain uncertain, its pathogenesis may involve oxidative stress via the generation of excess reactive oxygen species and/or destruction of the antioxidant system. One of the most powerful antioxidants is glutathione, which plays essential roles as an antioxidant enzyme cofactor, cysteine-storage molecule, major redox buffer, and neuromodulator, in addition to being a key antioxidant in the central nervous system. Glutathione levels are known to be reduced in neurodegenerative diseases. In addition, genes regulating redox states have been shown to be post-transcriptionally modified by microRNA (miRNA), one of the most important types of non-coding RNA. miRNAs have been reported to be dysregulated in several diseases, including MSA. In this review, we focused on the relation between glutathione deficiency, miRNA dysregulation and oxidative stress and their close relation with MSA pathology.