Upregulation of alpha-synuclein in neurons and glia in inflammatory demyelinating disease

Differential involvement of amyloidogenic evolvability in oligodendropathies; Multiple Sclerosis and Multiple System Atrophy

Although multiple sclerosis (MS) and multiple system atrophy (MSA) are both characterized by impaired oligodendrocytes (OLs), the aetiological relevance remains obscure. Given inherent stressors affecting OLs, the objective of the present study was to discuss the possible role of amyloidogenic evolvability (aEVO) in these conditions. Hypothetically, in aEVO, protofibrils of amyloidogenic proteins (APs), including β-synuclein and β-amyloid, might form in response to diverse stressors in parental brain. Subsequently, the AP protofibrils might be transmitted to offspring via germ cells in a prion-like fashion. By virtue of the stress information conferred by protofibrillar APs, the OLs in offspring's brain might be more resilient to forthcoming stressors, perhaps reducing MS risk. aEVO could be comparable to a gene for the inheritance of acquired characteristics. On the contrary, during ageing, MSA risk is increased through antagonistic pleiotropy. Consistently, the expression levels of APs are reduced in MS, but are increased in MSA compared to controls. Furthermore, β-synuclein, the non-amyloidogenic homologue of β-synuclein, might exert a buffering effect on aEVO, and abnormal β-synuclein could also increase MS and MSA disease activity. Collectively, a better understanding of the role of aEVO in the OL diseases might lead to novel interventions for such chronic degenerative conditions.

Predictive value of α-synuclein expression in peripheral blood of multiple sclerosis patients: A two-dimensional assessment of a selected biomarker

INTRODUCTION

Our study aimed to evaluate whether assessing α-synuclein expression levels in blood samples could provide a reliable and straightforward alternative to existing diagnostic and prognostic methods for neurodegenerative disorders, including multiple sclerosis (MS). We specifically investigated if α-synuclein and IL-6 expression levels from serum and peripheral blood mononuclear cells (PBMCs) could accurately predict MS severity in patients using a two-dimensional approach.

METHODS

We designed a case-control study to analyze the expression of α-synuclein and IL-6 in the peripheral blood of an MS patient group (n = 51) and a control group (n = 51). We statistically evaluated the PBMCs and serum profiles of α-synuclein and IL-6 in MS patients, along with their age of onset, disease duration, tobacco exposure, and Expanded Disability Status Scale (EDSS) score, using SPSS V22.0 software and GraphPad Prism V9.0.

RESULTS

Our findings indicate that α-synuclein production was significantly downregulated in MS patients. Principal component analysis also revealed distinct profiles between MS patients and controls. PBMCs and serum profiles of α-synuclein correlated with the EDSS score, suggesting that disease severity can be predicted using α-synuclein profiles. Moreover, α-synuclein showed a significant correlation with IL-6 and age of onset. Lastly, receiver operating characteristic curves of PBMCs and serum activity of α-synuclein profiles displayed discrimination with area under the curve values of 0.856 and 0.705, respectively.

CONCLUSION

Our results imply that measuring α-synuclein levels in both serum and PBMCs could be a valuable method for diagnosing and predicting MS severity, potentially serving as a non-invasive biomarker for the disease.

Involvement of TLR2-TLR4, NLRP3, and IL-17 in pain induced by a novel Sprague-Dawley rat model of experimental autoimmune encephalomyelitis

Up to 92% of patients suffering from multiple sclerosis (MS) experience pain, most without adequate treatment, and many report pain long before motor symptoms associated with MS diagnosis. In the most commonly studied rodent model of MS, experimental autoimmune encephalomyelitis (EAE), motor impairments/disabilities caused by EAE can interfere with pain testing. In this study, we characterize a novel low-dose myelin-oligodendrocyte-glycoprotein (MOG)-induced Sprague-Dawley (SD) model of EAE-related pain in male rats, optimized to minimize motor impairments/disabilities. Adult male SD rats were treated with increasing doses of intradermal myelin-oligodendrocyte-glycoprotein (MOG1-125) (0, 4, 8, and 16 μg) in incomplete Freund's adjuvant (IFA) vehicle to induce mild EAE. Von Frey testing and motor assessments were conducted prior to EAE induction and then weekly thereafter to assess EAE-induced pain and motor impairment. Results from these studies demonstrated that doses of 8 and 16 μg MOG1-125 were sufficient to produce stable mechanical allodynia for up to 1 month in the absence of hindpaw motor impairments/disabilities. In the follow-up studies, these doses of MOG1-125, were administered to create allodynia in the absence of confounded motor impairments. Then, 2 weeks later, rats began daily subcutaneous injections of the Toll-like receptor 2 and 4 (TLR2-TLR4) antagonist (+)-naltrexone [(+)-NTX] or saline for an additional 13 days. We found that (+)-NTX also reverses EAE-induced mechanical allodynia in the MOG-induced SD rat model of EAE, supporting parallels between models, but now allowing a protracted timecourse to be examined completely free of motor confounds. Exploring further mechanisms, we demonstrated that both spinal NOD-like receptor protein 3 (NLRP3) and interleukin-17 (IL-17) are necessary for EAE-induced pain, as intrathecal injections of NLRP3 antagonist MCC950 and IL-17 neutralizing antibody both acutely reversed EAE-induced pain. Finally, we show that spinal glial immunoreactivity induced by EAE is reversed by (+)-NTX, and that spinal demyelination correlates with the severity of motor impairments/disabilities. These findings characterize an optimized MOG-induced SD rat model of EAE for the study of pain with minimal motor impairments/disabilities. Finally, these studies support the role of TLR2-TLR4 antagonists as a potential treatment for MS-related pain and other pain and inflammatory-related disorders.

Risk of Parkinson's disease in multiple sclerosis and neuromyelitis optica spectrum disorder: a nationwide cohort study in South Korea

BACKGROUND

Neurodegeneration is associated with pathogenesis of both multiple sclerosis (MS) and neuromyelitis optica (NMOSD). Parkinson's disease (PD) is a representative neurodegenerative disease, however, whether MS or NMOSD is associated with risk of PD is not known.

METHODS

MS and NMOSD cohorts were collected from the Korean National Health Insurance Service between 1 January 2010 and 31 December 2017, using International Classification of Diseases 10th revision diagnosis codes and information in the Rare Intractable Disease management programme. The PD incidence rate that occurred after a 1-year lag period was calculated and compared with that of a control cohort matched for age, sex, hypertension, diabetes and dyslipidaemia in a 1:5 ratio.

RESULTS

The incidence rates of PD in patients with MS and NMOSD were 3.38 and 1.27 per 1000 person-years, respectively, and were higher than that of their matched control groups. The adjusted HR of PD was 7.73 (95% CI, 3.87 to 15.47) in patients with MS and 2.61 (95% CI, 1.13 to 6.02) in patients with NMOSD compared with matched controls. In both patients with MS and NMOSD, there were no significant differences in relative risk when stratified by sex, age, diabetes, hypertension and dyslipidaemia.

CONCLUSION

The PD risk was higher in patients with MS and NMOSD compared with healthy controls and was particularly high in patients with MS. Further investigations should be performed to determine the pathophysiology and occurrence of PD in patients with MS and NMOSD.

Movement Disorders in Multiple Sclerosis: An Update

Background:

Multiple sclerosis (MS), a subset of chronic primary inflammatory demyelinating disorders of the central nervous system, is closely associated with various movement disorders. These disorders may be due to MS pathophysiology or be coincidental. This review describes the full spectrum of movement disorders in MS with their possible mechanistic pathways and therapeutic modalities.

Methods:

The authors conducted a narrative literature review by searching for ‘multiple sclerosis’ and the specific movement disorder on PubMed until October 2021. Relevant articles were screened, selected, and included in the review according to groups of movement disorders.

Results:

The most prevalent movement disorders described in MS include restless leg syndrome, tremor, ataxia, parkinsonism, paroxysmal dyskinesias, chorea and ballism, facial myokymia, including hemifacial spasm and spastic paretic hemifacial contracture, tics, and tourettism. The anatomical basis of some of these disorders is poorly understood; however, the link between them and MS is supported by clinical and neuroimaging evidence. Treatment options are disorder-specific and often multidisciplinary, including pharmacological, surgical, and physical therapies.

Discussion:

Movements disorders in MS involve multiple pathophysiological processes and anatomical pathways. Since these disorders can be the presenting symptoms, they may aid in early diagnosis and managing the patient, including monitoring disease progression. Treatment of these disorders is a challenge. Further work needs to be done to understand the prevalence and the pathophysiological mechanisms responsible for movement disorders in MS.

Nanotechnology-Based Drug Delivery Strategies to Repair the Mitochondrial Function in Neuroinflammatory and Neurodegenerative Diseases

Mitochondria are vital organelles in eukaryotic cells that control diverse physiological processes related to energy production, calcium homeostasis, the generation of reactive oxygen species, and cell death. Several studies have demonstrated that structural and functional mitochondrial disturbances are involved in the development of different neuroinflammatory (NI) and neurodegenerative (ND) diseases (NI&NDDs) such as multiple sclerosis, Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. Remarkably, counteracting mitochondrial impairment by genetic or pharmacologic treatment ameliorates neurodegeneration and clinical disability in animal models of these diseases. Therefore, the development of nanosystems enabling the sustained and selective delivery of mitochondria-targeted drugs is a novel and effective strategy to tackle NI&NDDs. In this review, we outline the impact of mitochondrial dysfunction associated with unbalanced mitochondrial dynamics, altered mitophagy, oxidative stress, energy deficit, and proteinopathies in NI&NDDs. In addition, we review different strategies for selective mitochondria-specific ligand targeting and discuss novel nanomaterials, nanozymes, and drug-loaded nanosystems developed to repair mitochondrial function and their therapeutic benefits protecting against oxidative stress, restoring cell energy production, preventing cell death, inhibiting protein aggregates, and improving motor and cognitive disability in cellular and animal models of different NI&NDDs.

[A rare clinical case of comorbidity of early-onset Parkinson's disease and remitting multiple sclerosis]

Comorbidities of extrapyramidal disorders and multiple sclerosis (MS) are rare. The chance of a combination of MS and Parkinson's disease (PD) is less than 1 in 12.5 million. In total, 42 cases of joint development of these disorders are described in the literature. All described patients had no initial changes in the basal ganglia on MRI, and the development of MS was diagnosed after 1-8 years. Possible common links in the pathogenesis of neurodegenerative disease and MS, as well as the cumulative effect of the two diseases on the severity of axonal degeneration and neuronal loss are discussed. A description of a clinical case of a combination of early onset PD and relapsing-remitting multiple sclerosis is presented.

Fatty Acid Synthesis in Glial Cells of the CNS

Fatty acids (FAs) are of crucial importance for brain homeostasis and neural function. Glia cells support the high demand of FAs that the central nervous system (CNS) needs for its proper functioning. Additionally, FAs can modulate inflammation and direct CNS repair, thereby contributing to brain pathologies such Alzheimer’s disease or multiple sclerosis. Intervention strategies targeting FA synthesis in glia represents a potential therapeutic opportunity for several CNS diseases.

Role of the Peripheral Nervous System in PD Pathology, Diagnosis, and Treatment

Studies on Parkinson disease (PD) have mostly focused on the central nervous system—specifically, on the loss of mesencephalic dopaminergic neurons and associated motor dysfunction. However, the peripheral nervous system (PNS) is gaining prominence in PD research, with increasing clinical attention being paid to non-motor symptoms. Researchers found abnormal deposition of α-synuclein and neuroinflammation in the PNS. Attempts have been made to use these pathological changes during the clinical diagnosis of PD. Animal studies demonstrated that combined transplantation of autologous peripheral nerves and cells with tyrosine hydroxylase activity can reduce dopaminergic neuronal damage, and similar effects were observed in some clinical trials. In this review, we will systematically explain PNS performance in PD pathology and its clinical diagnostic research, describe PNS experimental results [especially Schwann cell (SC) transplantation in the treatment of PD animal models] and the results of clinical trials, and discuss future directions. The mechanism by which SCs produce such a therapeutic effect and the safety of transplantation therapy are briefly described.

Toll-like receptor 2 and 4 antagonism for the treatment of experimental autoimmune encephalomyelitis (EAE)-related pain

Neuropathic pain is a major symptom of multiple sclerosis (MS) with up to 92% of patients reporting bodily pain, and 85% reporting pain severe enough to cause functional disability. None of the available therapeutics target MS pain. Toll-like receptors 2 and 4 (TLR2/TLR4) have emerged as targets for treating a wide array of autoimmune disorders, including MS, as well as having demonstrated success at suppressing pain in diverse animal models. The current series of studies tested systemic TLR2/TLR4 antagonists in males and females in a low-dose Myelin oligodendrocyte glycoprotein (MOG) experimental autoimmune encephalomyelitis (EAE) model, with reduced motor dysfunction to allow unconfounded testing of allodynia through 50+ days post-MOG. The data demonstrated that blocking TLR2/TLR4 suppressed EAE-related pain, equally in males and females; upregulation of dorsal spinal cord proinflammatory gene expression for TLR2, TLR4, NLRP3, interleukin-1β, IkBα, TNF-α and interleukin-17; and upregulation of dorsal spinal cord expression of glial immunoreactivity markers. In support of these results, intrathecal interleukin-1 receptor antagonist reversed EAE-induced allodynia, both early and late after EAE induction. In contrast, blocking TLR2/TLR4 did not suppress EAE-induced motor disturbances induced by a higher MOG dose. These data suggest that blocking TLR2/TLR4 prevents the production of proinflammatory factors involved in low dose EAE pathology. Moreover, in this EAE model, TLR2/TLR4 antagonists were highly effective in reducing pain, whereas motor impairment, as seen in high dose MOG EAE, is not affected.

Low serum Α-SYNUCLEIN and oligomer Α-SYNUCLEIN levels in multiple sclerosis patients

INTRODUCTION

Multiple sclerosis (MS) is an autoimmune, inflammatory, demyelinating neurodegenerative disease progressing with attacks. Alpha-synuclein (α-Syn), a neuronal protein, has been previously associated with the inflammation and development of neurodegenerative diseases. Although the cause of neurodegeneration in multiple sclerosis is mainly associated with inflammation, α-Syn may play a role in the pathogenesis of MS, as in other classical neurodegenerative diseases such as synucleinopathies. In multiple sclerosis, α-Syn has been directly studied in central nervous system lesions and cerebrospinal fluid (CSF). However, there are few studies approaching variations in peripheral α-Syn in MS. The aim of our study was to investigate the correlation between disease progression and other clinical parameters by measuring serum α-Syn and oligomer α-Syn levels in MS patients.

MATERIAL AND METHOD

The study included 60 MS patients aged 18 years or older who were admitted to the Department of Neurology between 01.02.2020-01.04.2020 and diagnosed with MS according to the 2010 MC Donald criteria, and 60 age- and sex-matched healthy controls. Those who were in the MS attack period and received cortisone treatment in the past three months were excluded from the study. The serum α-Syn and oligomer α-Syn levels of the individuals in both groups were measured. The correlation between the serum α-Syn, oligomer α-Syn, oligomer α-Syn/α-Syn ratio levels of the MS patients and their age, disease duration, number of attacks, annualized relapse rate (ARR), disease type, EDSS scores and immunomodulatory drug type used was investigated. Statistical analysis was performed using the SPSS 22.0 software.

RESULTS

In our study, 73.3% of the MS patients were female and the mean age of the patients was 36.18 ± 9.5 years. The most common MS disease type was RRMS with 83.3%. Serum α-Syn (79.52 ± 34.81) and oligomer α-Syn (18.79 ± 10.48) levels were significantly lower in the MS patients compared to the control group (p < 0.001). Serum oligomer α-Syn/α-Syn ratio was higher in the MS patients compared to the control group and in SPMS compared to RRMS, but was not statistically significant. There was no significant correlation between the serum α-Syn, oligomer α-Syn and oligomer α-Syn/α-Syn ratio ratio of the MS patients and their age, disease duration, disease type, EDDS, ARR and immunomodulatory treatments. There was a significant positive correlation between α-Syn and oligomer α-Syn in MS patients (r: 0.29, p: 0.02).

CONCLUSION

In our study, serum α-Syn and oligomer α-Syn levels were lower in the MS patients compared to the control group. Low levels of α-Syn in MS may play a role in the development of neuroinflammation and may be a result of the diffuse neuronal and synaptic loss. There is a need for further studies on this subject.

Synuclein in neurodegeneration

Neurodegenerative diseases are a heterogeneous group of disorders characterized by gradual progressive neuronal loss in the central nervous system. Unfortunately, the pathogenesis of many of these diseases remains unknown. Synucleins are a family of small, highly charged proteins expressed predominantly in neurons. Following their discovery, much has been learned about their structure, function, interaction with other proteins and role in neurodegenerative disease over the last two decades. One of these proteins, α-Synuclein (α-Syn), appears to be involved in many neurodegenerative disorders. These include Parkinson's disease (PD), dementia with Lewy bodies (DLB), Rapid Eye Movement Sleep Behavior Disorder (RBD) and Pure Autonomic Failure (PAF), i.e., collectively termed α-synucleinopathies. This review focuses on α-Syn dysfunction in neurodegeneration and assesses its role in synucleinopathies from a biochemical, genetic and neuroimaging perspective.

alpha-Synuclein: a Modulator During Inflammatory CNS Demyelination

Neuroinflammation and demyelination are hallmarks of several neurological disorders such as multiple sclerosis and multiple system atrophy. To better understand the underlying mechanisms of de- and regeneration in respective diseases, it is critical to identify factors modulating these processes. One candidate factor is alpha-Synuclein (aSyn), which is known to be involved in the pathology of various neurodegenerative diseases. Recently, we have shown that aSyn is involved in the modulation of peripheral immune responses during acute neuroinflammatory processes. In the present study, the effect of aSyn deficiency on de- and regenerative events in the CNS was analyzed by using two different demyelinating animal models: chronic MOG_35–55-induced experimental autoimmune encephalomyelitis (EAE) and the cuprizone model. Histopathological analysis of spinal cord cross sections 8 weeks after EAE induction revealed a significant reduction of CNS inflammation accompanied by decreased myelin loss during late-stage inflammatory demyelination in aSyn-deficient mice. In contrast, after cuprizone-induced demyelination or remyelination following withdrawal of cuprizone, myelination and neuroinflammatory patterns were not affected by aSyn deficiency. These data provide further evidence for aSyn as regulator of peripheral immune responses under neuroinflammatory conditions, thereby also modulating degenerative events in late-stage demyelinating disease.

Dysregulated Lipid Metabolism and Its Role in α-Synucleinopathy in Parkinson's Disease

Parkinson’s disease (PD) is the second most common neurodegenerative disease, the main pathological hallmark of which is the accumulation of α-synuclein (α-syn) and the formation of filamentous aggregates called Lewy bodies in the brainstem, limbic system, and cortical areas. Lipidomics is a newly emerging field which can provide fresh insights and new answers that will enhance our capacity for early diagnosis, tracking disease progression, predicting critical endpoints, and identifying risk in pre-symptomatic persons. In recent years, lipids have been implicated in many aspects of PD pathology. Biophysical and lipidomic studies have demonstrated that α-syn binds preferentially not only to specific lipid families but also to specific molecular species and that these lipid-protein complexes enhance its interaction with synaptic membranes, influence its oligomerization and aggregation, and interfere with the catalytic activity of cytoplasmic lipid enzymes and lysosomal lipases, thereby affecting lipid metabolism. The genetic link between aberrant lipid metabolism and PD is even more direct, with mutations in GBA and SMPD1 enhancing PD risk in humans and loss of GALC function increasing α-syn aggregation and accumulation in experimental murine models. Moreover, a number of lipidomic studies have reported PD-specific lipid alterations in both patient brains and plasma, including alterations in the lipid composition of lipid rafts in the frontal cortex. A further aspect of lipid dysregulation promoting PD pathogenesis is oxidative stress and inflammation, with proinflammatory lipid mediators such as platelet activating factors (PAFs) playing key roles in arbitrating the progressive neurodegeneration seen in PD linked to α-syn intracellular trafficking. Lastly, there are a number of genetic risk factors of PD which are involved in normal lipid metabolism and function. Genes such as PLA2G6 and SCARB2, which are involved in glycerophospholipid and sphingolipid metabolism either directly or indirectly are associated with risk of PD. This review seeks to describe these facets of metabolic lipid dysregulation as they relate to PD pathology and potential pathomechanisms involved in disease progression, while highlighting incongruous findings and gaps in knowledge that necessitate further research.

α-Synuclein deficiency promotes neuroinflammation by increasing Th1 cell-mediated immune responses

Background

Increased α-synuclein immunoreactivity has been associated with inflammatory activity in multiple sclerosis (MS) lesions, but the function of α-synuclein in neuroinflammation remains unknown. The aim of this study was to examine the role of α-synuclein in immunological processes in murine experimental autoimmune encephalomyelitis (EAE) as a model of MS.

Findings

We studied EAE in wildtype (aSyn^+/+) and α-synuclein knockout (aSyn^−/−) mice on a C57BL/6N background. In the spleen and spinal cord of aSyn^+/+ mice, we observed a gradual reduction of α-synuclein expression during EAE, starting already in the pre-symptomatic disease phase. Compared to aSyn^+/+ mice, aSyn^−/− mice showed an earlier onset of symptoms but no differences in symptom severity at the peak of disease. Earlier symptom onset was accompanied by increased spinal cord infiltration of CD4⁺ T cells, predominantly of interferon-γ-producing T helper 1 (Th1) cells, and reduced infiltration of regulatory T cells, whereas antigen-presenting cells were unaltered. Pre-symptomatically, aSyn^−/− mice exhibited hyperproliferative CD4⁺ splenocytes consistent with increased splenic interleukin-2 mRNA expression, resulting in increased numbers of Th1 cells in the spleen at the onset of symptoms.

Conclusions

Our findings indicate a functional role of α-synuclein in early EAE by increasing Th1 cell-mediated immune response.

Pramipexole, a Dopamine D2/D3 Receptor-Preferring Agonist, Prevents Experimental Autoimmune Encephalomyelitis Development in Mice

Experimental autoimmune encephalomyelitis (EAE) is the most used animal model of multiple sclerosis (MS) for the development of new therapies. Dopamine receptors can modulate EAE and MS development, thus highlighting the potential use of dopaminergic agonists in the treatment of MS, which has been poorly explored. Herein, we hypothesized that pramipexole (PPX), a dopamine D2/D3 receptor-preferring agonist commonly used to treat Parkinson's disease (PD), would be a suitable therapeutic drug for EAE. Thus, we report the effects and the underlying mechanisms of action of PPX in the prevention of EAE. PPX (0.1 and 1 mg/kg) was administered intraperitoneally (i.p.) from day 0 to 40 post-immunization (p.i.). Our results showed that PPX 1 mg/kg prevented EAE development, abolishing EAE signs by blocking neuroinflammatory response, demyelination, and astroglial activation in spinal cord. Moreover, PPX inhibited the production of inflammatory cytokines, such as IL-17, IL-1β, and TNF-α in peripheral lymphoid tissue. PPX was also able to restore basal levels of a number of EAE-induced effects in spinal cord and striatum, such as reactive oxygen species, glutathione peroxidase, parkin, and α-synuclein (α-syn). Thus, our findings highlight the usefulness of PPX in preventing EAE-induced motor symptoms, possibly by modulating immune cell responses, such as those found in MS and other T helper cell-mediated inflammatory diseases.

Intracellular alpha-synuclein affects early maturation of primary oligodendrocyte progenitor cells

Myelin loss is a widespread neuropathological hallmark of the atypical parkinsonian disorder multiple system atrophy (MSA). On a cellular level, MSA is characterized by alpha-synuclein (aSyn)-positive glial cytoplasmic inclusions (GCIs) within mature oligodendrocytes leading to demyelination as well as axonal and neuronal loss. Oligodendrocyte progenitor cells (OPCs) represent a proliferative cell population distributed throughout the adult mammalian central nervous system. During remyelination, OPCs are recruited to sites of demyelination, differentiate, and finally replace dysfunctional mature oligodendrocytes. However, comprehensive studies investigating OPCs and remyelination processes in MSA are lacking. In the present study, we therefore investigate the effect of human aSyn (h-aSyn) on early primary rat OPC maturation. Upon lentiviral transduction, h-aSyn expressing OPCs exhibit fewer and shorter primary processes at the initiation of differentiation. Until day 4 of a 6day differentiation paradigm, h-aSyn expressing OPCs further show a severely delayed maturation evidenced by reduced myelin gene expression and increased levels of the progenitor marker platelet derived growth factor receptor-alpha (PDGFRα). Matching these results, OPCs that take up extracellular recombinant h-aSyn exhibit a similar delayed differentiation. In both experimental setups however, myelin gene expression is restored at day 6 of differentiation paralleled by decreased intracellular h-aSyn levels indicating a reverse correlation of h-aSyn and the differentiation potential of OPCs. Taken together, these findings suggest a tight link between the intracellular level of h-aSyn and maturation capacity of primary OPCs.

Lipopolysaccharide-induced blood brain barrier permeability is enhanced by alpha-synuclein expression

Because α-synuclein (Snca) is involved in neuroinflammatory response, we determined if its expression altered blood-brain barrier (BBB) permeability. To induce increased BBB permeability, Snca gene-ablated (KO) and wild-type (WT) mice were injected (i.p.) with lipopolysaccharide (LPS). To assess changes in BBB permeability, Evans blue was injected (i.p.) and extravasation into the brain assessed using fluorescence spectroscopy. WT mice had a significant increase in BBB permeability at 1, 3, and 6h post-injection of LPS relative to untreated mice. Contrary to WT mice, LPS did not induce a time-dependent change in BBB permeability in KO mice. Although brain edema is associated with increased BBB permeability, no significant difference in edema was found between groups. These results show that Snca expression is associated with increased reactive opening of the BBB in response to LPS.

Identification and quantification of oligodendrocyte precursor cells in multiple system atrophy, progressive supranuclear palsy and Parkinson's disease

Multiple system atrophy is a neurodegenerative disorder characterized pathologically by abnormal accumulations of α-synuclein in the cytoplasm of oligodendrocytes, which are termed glial cytoplasmic inclusions (GCIs). Oligodendrocytes are responsible for myelinating axons and providing neurotrophic support, but in MSA, myelin loss, axonal loss and gliosis are consistent features suggesting that GCIs play a central role in disease pathogenesis. Oligodendroglial, myelin and axonal degeneration are also features of multiple sclerosis (MS) in which recent studies have highlighted the robust remyelination capacity of the central nervous system (CNS). The cells responsible for remyelination are called oligodendroglial precursor cells (OPCs). In this study, we investigated the role of OPCs in the pathogenesis of MSA and progressive supranuclear palsy (PSP), a neurodegenerative disease in which neuropathological changes include oligodendroglial inclusions composed of microtubule-associated protein tau. Despite the lability of OPC-specific antigens, we successfully identified OPCs and demonstrated that tau and α-synuclein do not accumulate in OPCs. We also showed that the density of OPCs was increased in a white matter region of the MSA brain, which is also severely affected by GCIs and myelin degeneration. These findings raise the possibility that OPCs could be available to repair disease-associated damage in MSA, consistent with their biological function.

The synucleins are a family of redox-active copper binding proteins

Thermodynamic studies in conjunction with EPR confirm that α-synuclein, β-synuclein, and γ-synuclein bind copper(II) in a high affinity 1:1 stoichiometry. γ-Synuclein demonstrates the highest affinity, in the picomolar range, while α-synuclein and β-synuclein both bind copper(II) with nanomolar affinity. The copper center on all three proteins demonstrates reversible or partly reversible redox cycling. Various mutations show that the primary coordinating ligand for copper(II) is located within the N-terminal regions between residues 2-9. There is also a contribution from the C-terminus in conjunction with the histidine at position 50 in α-synuclein and position 65 in β-synuclein, although these regions appear to have little effect on overall coordination stability. These histidines and the C-terminus, however, appear to be critical to the redox engine of the proteins.

Protein coding of neurodegenerative dementias: the neuropathological basis of biomarker diagnostics

Neuropathological diagnosis of neurodegenerative dementias evolved by adapting the results of neuroanatomy, biochemistry, and cellular and molecular biology. Milestone findings of intra- and extracellular argyrophilic structures, visualizing protein deposition, initiated a protein-based classification. Widespread application of immunohistochemical and biochemical investigations revealed that (1) there are modifications of proteins intrinsic to disease (species that are phosphorylated, nitrated, oligomers, proteinase-resistant, with or without amyloid characteristics; cleavage products), (2) disease forms characterized by the accumulation of a single protein only are rather the exception than the rule, and (3) some modifications of proteins elude present neuropathological diagnostic procedures. In this review, we summarize how neuropathology, together with biochemistry, contributes to disease typing, by demonstrating a spectrum of disorders characterized by the deposition of various modifications of various proteins in various locations. Neuropathology may help to elucidate how brain pathologies alter the detectability of proteins in body fluids by upregulation of physiological forms or entrapment of different proteins. Modifications of at least the five most relevant proteins (amyloid-beta, prion protein, tau, alpha-synuclein, and TDP-43), aided by analysis of further "attracted" proteins, are pivotal to be evaluated simultaneously with different methods. This should complement the detection of biomarkers associated with pathogenetic processes, and also neuroimaging and genetic analysis, in order to obtain a highly personalized diagnostic profile. Defining clusters of patients based on the patterns of protein deposition and immunohistochemically or biochemically detectable modifications of proteins ("codes") may have higher prognostic predictive value, may be useful for monitoring therapy, and may open new avenues for research on pathogenesis.

Regulation of matrix metalloproteinase-9 and tissue plasminogen activator activity by alpha-synuclein in rat primary glial cells

It is increasingly evident that neuroinflammatory response is involved in the pathogenesis of Parkinson's disease. In this study, we examined whether alpha-synuclein, a major components of Lewy body that has been implicated in the modulation of neuroinflammation, regulates MMP-9 and tPA activity, which plays important roles in neurodegeneration as well as regeneration processes, in cultured rat primary glial cells. Monomeric alpha-synuclein dose-dependently increased MMP-9 but not MMP-2 activity as well as mRNA level from cultured rat primary astrocytes and microglial cells. Maximal stimulation was observed at 50 nM alpha-synuclein. In contrast, the activity of tPA was decreased by alpha-synuclein with only marginal changes in the level of mRNA encoding tPA, if any. Interestingly, same concentration of alpha-synuclein aggregates did not induce MMP-9 activity. Overexpression of alpha-synuclein in rat primary astrocytes similarly increased MMP-9 activity. Treatment of alpha-synuclein increased the phosphorylation of ERK1/2 and the inhibition of ERK1/2 reversed the changes in MMP-9 and tPA activity. These results suggest further functional role of alpha-synuclein via regulation of protease systems through modulation of ERK1/2 activity in brain.

Naturally presented peptides on major histocompatibility complex I and II molecules eluted from central nervous system of multiple sclerosis patients

Tandem mass spectrometry was used to identify naturally processed peptides bound to major histocompatibility complex (MHC) I and MHC II molecules in central nervous system (CNS) of eight patients with multiple sclerosis (MS). MHC molecules were purified from autopsy CNS material by immunoaffinity chromatography with monoclonal antibody directed against HLA-A, -B, -C, and -DR. Subsequently peptides were separated by reversed-phase HPLC and analyzed by mass spectrometry. Database searches revealed 118 amino acid sequences from self-proteins eluted from MHC I molecules and 191 from MHC II molecules, corresponding to 174 identified source proteins. These sequences define previously known and potentially novel autoantigens in MS possibly involved in disease induction and antigen spreading. Taken together, we have initiated the characterization of the CNS-expressed MHC ligandome in CNS diseases and were able to demonstrate the presentation of naturally processed myelin basic protein peptides in the brain of MS patients.

Alpha-synuclein and its role in metal binding: Relevance to Parkinson's disease

Parkinson's disease and some other neurodegenerative disorders are associated with a protein that can aggregate and form fibrils called alpha-synuclein. Like many other proteins associated with neurodegenerative disorders, this protein has no known function, and the mechanism by which it could cause diseases is poorly defined. It was recently suggested that it binds copper. This review assesses what is known about alpha-synuclein and its interaction with metals.

Brain prostaglandin formation is increased by alpha-synuclein gene-ablation during global ischemia

We have previously demonstrated that alpha-synuclein (Snca) gene ablation reduces brain arachidonic acid (20:4n-6) turnover rate in phospholipids through modulation of endoplasmic reticulum-localized acyl-CoA synthetase activity. Although 20:4n-6 is a precursor for prostaglandin (PG), Snca effect on PG levels is unknown. In the present study, we examined the effect of Snca ablation on brain PG level at basal conditions and following 30s of global ischemia. Brain PG were extracted with methanol, purified on C(18) cartridges, and analyzed by LC-MS/MS. We demonstrate, for the first time, that Snca gene ablation did not affect brain PG mass under normal physiological conditions. However, total PG mass and masses of individual PG were elevated approximately 2-fold upon global ischemia in the absence of Snca. These data are consistent with our previously observed reduction in 20:4n-6 recycling through endoplasmic reticulum-localized acyl-CoA synthetase in the absence of Snca, which may result in the increased 20:4n-6 availability for PG production in the absence of Snca during global ischemia and suggest a role for Snca in brain inflammatory response.

p25alpha relocalizes in oligodendroglia from myelin to cytoplasmic inclusions in multiple system atrophy

p25alpha is an oligodendroglial protein that can induce aggregation of alpha-synuclein and accumulates in oligodendroglial cell bodies containing fibrillized alpha-synuclein in the neurodegenerative disease multiple system atrophy (MSA). We demonstrate biochemically that p25alpha is a constituent of myelin and a high-affinity ligand for myelin basic protein (MBP), and in situ immunohistochemistry revealed that MBP and p25alpha colocalize in myelin in normal human brains. Analysis of MSA cases reveals dramatic changes in p25alpha and MBP throughout the course of the disease. In situ immunohistochemistry revealed a cellular redistribution of p25alpha immunoreactivity from the myelin to the oligodendroglial cell soma, with no overall change in p25alpha protein concentration using immunoblotting. Concomitantly, an approximately 80% reduction in the concentration of full-length MBP protein was revealed by immunoblotting along with the presence of immunoreactivity for MBP degradation products in oligodendroglia. The oligodendroglial cell bodies in MSA displayed an enlargement along with the relocalization of p25alpha, and this was enhanced after the deposition of alpha-synuclein in the glial cytoplasmic inclusions. Overall, the data indicate that changes in the cellular interactions between MBP and p25alpha occur early in MSA and contribute to abnormalities in myelin and subsequent alpha-synuclein aggregation and the ensuing neuronal degeneration that characterizes this disease.

Brain neutral lipids mass is increased in alpha-synuclein gene-ablated mice

Because alpha-synuclein (Snca) has a role in brain lipid metabolism, we determined the impact that Snca deletion had on whole brain lipid composition. We analysed masses of individual phospholipid (PL) classes and neutral lipid mass as well as PL acyl chain composition in brains from wild-type and Snca-/- mice. Although total brain PL mass was not altered, cardiolipin and phosphatidylglycerol mass decreased 16% and 27%, respectively, in Snca-/- mice. In addition, no changes were observed in plasmalogen or polyphosphoinositide mass. In ethanolamine glycerophospholipids and phosphatidylserine, docosahexaenoic acid (22 : 6n-3) was decreased 7%, while 16 : 0 was increased 1.1-fold and 1.4-fold, respectively. Surprisingly, brain cholesterol, cholesteryl ester, and triacylglycerol mass were increased 1.1-fold, 1.6-fold, and 1.4-fold, respectively in Snca-/- mice. In isolated myelin, cholesterol mass was also increased 1.3-fold, but because there was also a net increase in myelin PL mass, the cholesterol to PL ratio was unaltered. No changes in the expression of cholesterogenic enzymes were observed, suggesting these did not account for the observed changes in cholesterol. These data extend our previous results in astrocytes and kinetic studies in vivo demonstrating a role for Snca in brain lipid metabolism and demonstrate a clear impact on brain neutral lipid metabolism.

α-Synuclein gene ablation increases docosahexaenoic acid incorporation and turnover in brain phospholipids

Previously, we demonstrated that ablation of alpha-synuclein (Snca) reduces arachidonate (20:4n-6) turnover in brain phospholipids through modulation of an endoplasmic reticulum-localized acyl-CoA synthetase (Acsl). The effect of Snca ablation on docosahexaenoic acid (22:6n-3) metabolism is unknown. In the present study, we examined the effect of Snca gene ablation on brain 22:6n-3 metabolism. We determined 22:6n-3 uptake and incorporation into brain phospholipids by infusing awake, wild-type and Snca-/- mice with [1-14C]22:6n-3 using steady-state kinetic modeling. In addition, because Snca modulates 20:4n-6-CoA formation, we assessed microsomal Acsl activity using 22:6n-3 as a substrate. Although Snca gene ablation does not affect brain 22:6n-3 uptake, brain 22:6n-3-CoA mass was elevated 1.5-fold in the absence of Snca. This is consistent with the 1.6- to 2.2-fold increase in the incorporation rate and turnover in ethanolamine glycerophospholipid, phosphatidylserine, and phosphatidylinositol pools. Increased 22:6n-3-CoA mass was not the result of altered Acsl activity, which was unaffected by the absence of Snca. While Snca bound 22:6n-3, Kd = 1.0 +/- 0.5 micromol/L, it did not bind 22:6n-3-CoA. These effects of Snca gene deletion on 22:6n-3 brain metabolism are opposite to what we reported previously for brain 20:4n-6 metabolism and are likely compensatory for the decreased 20:4n-6 metabolism in brains of Snca-/- mice.