Mesenchymal stem cells in a transgenic mouse model of multiple system atrophy: immunomodulation and neuroprotection

BACKGROUND

Mesenchymal stem cells (MSC) are currently strong candidates for cell-based therapies. They are well known for their differentiation potential and immunoregulatory properties and have been proven to be potentially effective in the treatment of a large variety of diseases, including neurodegenerative disorders. Currently there is no treatment that provides consistent long-term benefits for patients with multiple system atrophy (MSA), a fatal late onset α-synucleinopathy. Principally neuroprotective or regenerative strategies, including cell-based therapies, represent a powerful approach for treating MSA. In this study we investigated the efficacy of intravenously applied MSCs in terms of behavioural improvement, neuroprotection and modulation of neuroinflammation in the (PLP)-αsynuclein (αSYN) MSA model.

METHODOLOGY/PRINCIPAL FINDINGS

MSCs were intravenously applied in aged (PLP)-αSYN transgenic mice. Behavioural analyses, defining fine motor coordination and balance capabilities as well as stride length analysis, were performed to measure behavioural outcome. Neuroprotection was assessed by quantifying TH neurons in the substantia nigra pars compacta (SNc). MSC treatment on neuroinflammation was analysed by cytokine measurements (IL-1α, IL-2, IL-4, IL-5, IL-6, IL-10, IL-17, GM-CSF, INFγ, MCP-1, TGF-β1, TNF-α) in brain lysates together with immunohistochemistry for T-cells and microglia. Four weeks post MSC treatment we observed neuroprotection in the SNc, as well as downregulation of cytokines involved in neuroinflammation. However, there was no behavioural improvement after MSC application.

CONCLUSIONS/SIGNIFICANCE

To our knowledge this is the first experimental approach of MSC treatment in a transgenic MSA mouse model. Our data suggest that intravenously infused MSCs have a potent effect on immunomodulation and neuroprotection. Our data warrant further studies to elucidate the efficacy of systemically administered MSCs in transgenic MSA models.

Interleukin-1A (?889) genetic polymorphism increases the risk of multiple system atrophy

In a case-control study using a clinically well-defined group of 30 multiple system atrophy (MSA) patients and 110 control subjects, homozygosity for interleukin-1A (IL-1A) allele 2 (high secretor of proinflammatory cytokine) in the regulatory region (-889) of the IL-1A gene was associated with a fivefold increased risk for MSA.

Olfactory bulb in multiple system atrophy

Olfactory dysfunction is a characteristic clinical sign in Parkinson's disease (PD); it is also present in multiple system atrophy (MSA). The pathological basis of hyposmia or anosmia in PD is well known: the olfactory bulb (OB) contains numerous Lewy bodies and severe neuronal loss is present in the anterior olfactory nucleus (AON). We established that glial cytoplasmic inclusions (GCIs) are present in all the OBs from MSA cases. Their presence in the OB is diagnostic for MSA. Additionally, neuronal loss is present in the AON in MSA. These pathological changes might be responsible for the olfactory dysfunction seen in MSA.

Leucine-rich repeat kinase 2 expression leads to aggresome formation that is not associated with alpha-synuclein inclusions

Mutations in leucine-rich repeat kinase-2 (LRRK2) are the most common known cause of Parkinson disease, but how this protein results in the pathobiology of Parkinson disease is unknown. Moreover, there is variability in pathology among cases, and alpha-synuclein (alpha-syn) neuronal inclusions are often present, but whether LRRK2 is present in these pathological inclusions is controversial. This study characterizes novel LRRK2 antibodies, some of which preferentially recognize an aggregated form of LRRK2, as observed in cell culture models. Large perinuclear aggregates containing LRRK2 were promoted by proteasome inhibition and prevented by microtubule polymerization inhibition. Furthermore, they were vimentin- and gamma-tubulin- but not lamp1-immunoreactive, suggesting that these structures fit the definition of aggresomes. Inhibition of heat shock protein 90 led to the degradation of only the soluble/cytosolic pool of LRRK2, suggesting that the aggresomes formed independent of the stability provided by the heat shock protein 90. Although these novel anti-LRRK2 antibodies identified aggregates in model cell systems, they did not immunostain pathological inclusions in human brains. Furthermore, coexpression of LRRK2 and alpha-syn did not recruit alpha-syn into aggresomes in cultured cells, even in the presence of proteasome inhibition. Thus, although LRRK2 is a model system for aggresome formation, LRRK2 is not present in alpha-syn pathological inclusions.

Anti-ganglioside antibodies in idiopathic and hereditary cerebellar degeneration

Cerebellar degeneration has been associated with gluten sensitivity and celiac disease. Patients with celiac disease may have neuropathy and antibodies to gangliosides. The authors investigated the presence of antiganglioside antibodies in 22 patients with hereditary and nonhereditary ataxia and found 64% reactive in a novel agglutination test.

Elevated titers of anti-thyroperoxidase antibodies in patients with multiple system atrophy: a pilot study

OBJECTIVES

Multiple system atrophy (MSA) is a neurodegenerative disease characterized by progressive neuronal loss and alpha-synuclein deposition in oligodendroglial cells in the central nervous system. The cause of MSA remains essentially unknown. A cerebellar syndrome was associated with autoimmune thyroid disease in some cases, apparently not related to MSA and was partially responsive to immunomodulatory therapy.

PATIENTS AND METHODS

28 euthyroid patients who fulfilled the diagnostic criteria for probable MSA, 11 with MSA-cerebellar type (MSA-C), 17 with MSA-parkinsonian type (MSA-P), 28 patients with Parkinson's disease (PD) and 26 normal euthyroid controls were tested the for serum levels of anti-thyroperoxidase antibodies (anti-TPO) and anti-thyroglobulin (Anti-TG) antibodies (Ab).

RESULTS

The laboratory results were statistically similar in all three groups, but 3 MSA-C patients had highly elevated anti-TPO Ab titers.

CONCLUSION

We identified the presence of elevated anti-TPO levels in a small subgroup of MSA-C patients but neither in MSA-P or PD patients nor in healthy controls. These findings may suggest an autoimmune etiology in some cases of MSA-C.

Nigral Neuroinflammation and Dopaminergic Neurons in Parkinson's Disease and Atypical Parkinsonisms

OBJECTIVE

To investigate the role of neuroinflammation in the substantia nigra pars compacta (SNc) across different parkinsonian disorders-Parkinson's disease (PD), progressive supranuclear palsy (PSP), and multiple system atrophy (MSA)-by examining SNc dopaminergic neuron counts, neuroinflammatory T cells, and microglial activity.

METHODS

Postmortem neuropathological samples were collected from 79 individuals (PD, n = 38; PSP, n = 15; MSA, n = 14; controls, n = 12). The density of SNc tyrosine hydroxylase (TH)-positive neurons, T cells (CD3+, CD4+, and CD8+), and Iba1 expression (Iba1-positive microglia/macrophages) were examined in the SNc and crus cerebri. Demographic and clinical data were gathered from patient histories.

RESULTS

PSP patients had 89 to 212% more nigral CD3+, CD4+, and CD8+ T cells compared to MSA patients (p < 0.04), 125 to 178% more CD3+ and CD4+ T cells than healthy controls (p < 0.002), and 95% more CD4+ T cells than PD patients (p = 0.001). Iba1 expression in the SNc was higher in PD patients than in MSA patients (p = 0.004), with no significant differences observed across other conditions. There was a negative association between disease duration and SNc CD3+ T cell density (p = 0.002), and a positive correlation between nigral dopaminergic neuron density and CD3+ density, CD8+ density, and Iba1 expression in PD patients.

INTERPRETATION

The study reveals distinctive neuroinflammatory patterns in the SNc, with T cell-mediated inflammation prominent in PSP and microglia-mediated inflammation in PD. PSP and MSA show greater SNc dopaminergic neuron loss compared to PD. Increased neuroinflammatory response is seen in earlier disease stages, diminishing with greater neuron loss, which may inform disease progression understanding and therapeutic strategies. ANN NEUROL 2025;97:1096-1109.

Prevalence of anti-locus coeruleus immunoreactivity in CSF of patients with autonomic failure

In this study we evaluated by indirect immunohistochemistry the prevalence of cerebrospinal fluid (CSF) antibodies reacting with structures of rat pons/medulla in patients with multiple system atrophy (MSA) (n = 29), Parkinson disease with neurogenic orthostatic hypotension (n = 13), or pure autonomic failure (n = 11) and in control subjects without autonomic failure (n = 33). About 10-20% of CSF samples had positive immunoreactivity to rat locus coeruleus (LC), regardless of clinical diagnosis. The results failed to confirm the previously reported high prevalence of immune binding to rat LC in CSF from patients with MSA.

[Two patients of immunotherapy-responsive autoimmune cerebellar ataxia fulfilled with criteria of multiple system atrophy]

We report two patients with autoimmune cerebellar ataxia who fulfilled the diagnostic criteria of multiple system atrophy (MSA) and responded to immunotherapies. Patient 1 was a 72-year-old man who was diagnosed with clinically probable MSA according to Movement Disorder Society criteria. Patient 2 was a 68-year-old man who was diagnosed with clinically established MSA according to Movement Disorder Society criteria. Both patients showed cerebellar ataxia, autonomic dysfunction, and pyramidal tract signs; however, they also had atypical clinical features. Patient 1 exhibited self-‍limiting mild improvement of clinical symptoms and had inflammatory findings in his cerebrospinal fluid. Patient 2 showed a rapidly progressive clinical course. We therefore examined anti-neuronal antibodies using tissue-based immunohistochemical assays with frozen rat cerebellum sections. We detected autoantibodies that mainly reacted with the cytoplasm of Purkinje cells. The two patients then underwent immunotherapies, which led to substantial improvements in their clinical symptoms. Our findings indicate that some patients with autoimmune cerebella ataxia have clinical features that resemble MSA, and respond well to immunotherapies.

A multiverse of α-synuclein: investigation of prion strain properties with carboxyl-terminal truncation specific antibodies in animal models

Synucleinopathies are a group of neurodegenerative disorders characterized by the presence of misfolded α-Synuclein (αSyn) in the brain. These conditions manifest with diverse clinical and pathophysiological characteristics. This disease diversity is hypothesized to be driven by αSyn strains with differing biophysical properties, potentially influencing prion-type propagation and consequentially the progression of illness. Previously, we investigated this hypothesis by injecting brain lysate (seeds) from deceased individuals with various synucleinopathies or human recombinant αSyn preformed fibrils (PFFs) into transgenic mice overexpressing either wild type or A53T human αSyn. In the studies herein, we expanded on these experiments, utilizing a panel of antibodies specific for the major carboxyl-terminally truncated forms of αSyn (αSynΔC). These modified forms of αSyn are found enriched in human disease brains to inform on potential strain-specific proteolytic patterns. With monoclonal antibodies specific for human αSyn cleaved at residues 103, 114, 122, 125, and 129, we demonstrate that multiple system atrophy (MSA) seeds and PFFs induce differing neuroanatomical spread of αSyn pathology associated with host specific profiles. Overall, αSyn cleaved at residue 103 was most widely present in the induced pathological inclusions. Furthermore, αSynΔC-positive inclusions were present in astrocytes, but more frequently in activated microglia, with patterns dependent on host and inoculum. These findings support the hypothesis that synucleinopathy heterogeneity might stem from αSyn strains with unique biochemical properties that include proteolytic processing, which could result in dominant strain properties.