Oxidative-stress-induced apoptosis in PBLs of two patients with Parkinson disease secondary to alpha-synuclein mutation

Dysfunction of thioredoxin triggers inflammation through activation of autophagy in chicken cardiomyocytes

Thioredoxin (Txn) is a hydrogen carrier protein and exists widely in organism. Txn deficiency implicates cardiomyocytes injury has been proven. However, the exact mechanism remains unclear. To understand the mechanistic response of cardiomyocytes subsequent to Txn suppression, we established the model of Txn dysfunction by employing gene interference technology (siRNA) and Txn inhibitor (PX-12) in cardiomyocytes. We detected the ROS levels, inflammation factors, and key proteins in the autophagy and apoptosis. In addition, heat map was used for further analysis. Our results revealed that Txn dysfunction increased the release of ROS and induced activation of autophagy via upregulation of Becline-1, LC3-1, 2, which further regulated the inflammatory response, meanwhile, Txn silence inhibited apoptosis in chicken cardiomyocytes through Caspase-3 inhibition. Altogether we concluded that Txn-deficient chicken cardiomyocytes experienced autophagy, which caused severe inflammatory reactions and resulting in damage to cardiomyocytes.

Triflumuron induces cytotoxic effects on hepatic and renal human cell lines

Insect growth regulator insecticides are a new class of pesticides, commonly used around the world to control insect damages. Among those compounds, we focused our interest on triflumuron (TFM), which is less toxic than other conventional insecticides. However, not much is known about its toxic effects on mammalian systems. Therefore, our study aimed toward evaluating the cytotoxic and genotoxic effects of TFM using two different cell lines, the human renal embryonic cells (HEK 293) and hepatocytes (Hep G2). We showed, according to the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, that TFM reduced significantly the cell viability and increased the reactive oxygen species generation, malondialdehyde levels, and mitochondrial membrane potential in both cell lines. The antioxidant system was disturbed as assessed by the increased activities in both catalase and superoxide dismutase. We demonstrated also, that TFM is an inductor of DNA damages quantified by the comet assay. Moreover, we showed an overexpression of proapoptotic Bax and a decrease in antiapoptotic Bcl-2 expression. As a conclusion, we demonstrate that the liver presents the major target organ to TFM, in which the cytotoxicity and the genotoxic effects were significantly higher in hepatic cells than in renal cells and by consequence its uses must be controlled.

Protective effects of fennel essential oil against oxidative stress and genotoxicity induced by the insecticide triflumuron in human colon carcinoma cells

The increased use of pesticides is the origin of multiple damages to the environment and to humans; thus, the search for new strategies to reduce or even protect the toxic effects caused by these synthetic products became a necessity. In this context, our study attempted to evaluate the protective effects of fennel essential oil (FEO), the main essential oil extracted from Faeniculum vulgare Mill., a plant with aromatic, flavorful, and medicinal uses, against toxicity induced by an insecticide-triflumuron (TFM)-in human carcinoma cells (HCT116). Our methodological approach consists of the cytotoxicity assay starting with the cell viability test, the ROS generation, the malondialdehyde (MDA) production, the DNA fragmentation, and the measurement of some antioxidant enzymes activities such as catalase (CAT) and superoxide dismutase (SOD). Also, we measured the mitochondrial transmembrane potential. The outcome of the current study showed clearly that after 2 h of HCT 116 cell pretreatment with FEO, there were increase in cell viability, reduction in ROS generation, and modulation in CAT and SOD activities induced by TFM. In the same manner, significant decreases in MDA levels were found. Mainly, the results indicated a perceptible decrease in DNA damages and a significant reduction in the mitochondrial membrane potential loss. Our work demonstrates that FEO can be an important protector against toxic effects induced by TFM in HCT 116 cells.

Interaction of systemic oxidative stress and mesial temporal network degeneration in Parkinson's disease with and without cognitive impairment

Background

To identify the vulnerable areas associated with systemic oxidative stress and further disruption of these vulnerable areas by measuring the associated morphology and functional network alterations in Parkinson’s disease (PD) patients with and without cognitive impairment.

Methods

This prospective study was approved by the institutional review board of KCGMH, and written informed consent was obtained. Between December 2010 and May 2015, 41 PD patients with different levels of cognitive functions and 29 healthy volunteers underwent peripheral blood sampling to quantify systemic oxidative stress, as well as T1W volumetric and resting state functional MRI (rs-fMRI) scans. Rs-fMRI was used to derive the healthy intrinsic connectivity patterns seeded by the vulnerable areas associated with any of the significant oxidative stress markers. The two groups were compared in terms of the functional connectivity correlation coefficient (fc-CC) and gray matter volume (GMV) of the network seeded by the vulnerable areas.

Results

The levels of oxidative stress markers, including leukocyte apoptosis and adhesion molecules, were significantly higher in the PD group. Using whole-brain VBM-based correlation analysis, the bilateral mesial temporal lobes (MTLs) were identified as the most vulnerable areas associated with lymphocyte apoptosis (P < 0.005). We found that the MTL network of healthy subjects resembled the PD-associated atrophy pattern. Furthermore, reduced fc-CC and GMV were further associated with the aggravated cognitive impairment.

Conclusion

The MTLs are the vulnerable areas associated with peripheral lymphocyte infiltration, and disruptions of the MTL functional network in both architecture and functional connectivity might result in cognitive impairments in Parkinson’s disease.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1317-z) contains supplementary material, which is available to authorized users.

CD4 T cells react to local increase of α-synuclein in a pathology-associated variant-dependent manner and modify brain microglia in absence of brain pathology

We have previously shown that immunological processes in the brain during α-synuclein-induced neurodegeneration vary depending on the presence or absence of cell death. This suggests that the immune system is able to react differently to the different stages of α-synuclein pathology. However, it was unclear whether these immune changes were governed by brain processes or by a direct immune response to α-synuclein modifications. We have herein locally increased the peripheral concentration of α-synuclein or its pathology-associated variants, nitrated or fibrillar, to characterize the modulation of the CD4 T cell pool by α-synuclein and brain microglia in the absence of any α-synuclein brain pathology. We observed that α-synuclein changed the CD4:CD8 ratio by contracting the CD3+CD4+ T cell pool and reducing the pool of memory Regulatory T cells (Treg). Nitrated α-synuclein induced the expansion of both the CD3+CD4+ and CD3+CD4- T cells, while fibrils increased the percentage of Foxp3+ Treg cells and induced anti-α-synuclein antibodies. Furthermore, the activation pattern of CD3+CD4+ T cells was modulated in a variant-dependent manner; while nitrated and fibrillar α-synuclein expanded the fraction of activated Treg, all three α-synuclein variants reduced the expression levels of STAT3, CD25 and CD127 on CD3+CD4+ T cells. Additionally, while monomeric α-synuclein increased CD103 expression, the fibrils decreased it, and CCR6 expression was decreased by nitrated and fibrillar α-synuclein, indicating that α-synuclein variants affect the homing and tolerance capacities of CD3+CD4+ T cells. Indeed, this correlated with changes in brain microglia phenotype, as determined by FACS analysis, in an α-synuclein variant-specific manner and coincided in time with CD4+ T cell infiltration into brain parenchyma. We have shown that the peripheral immune system is able to sense and react specifically to changes in the local concentration and structure of α-synuclein, which results in variant-specific T cell migration into the brain. This may have a specific repercussion for brain microglia.

Blood RNA biomarkers in prodromal PARK4 and rapid eye movement sleep behavior disorder show role of complexin 1 loss for risk of Parkinson's disease

Parkinson's disease (PD) is a frequent neurodegenerative process in old age. Accumulation and aggregation of the lipid-binding SNARE complex component α-synuclein (SNCA) underlies this vulnerability and defines stages of disease progression. Determinants of SNCA levels and mechanisms of SNCA neurotoxicity have been intensely investigated. In view of the physiological roles of SNCA in blood to modulate vesicle release, we studied blood samples from a new large pedigree with SNCA gene duplication (PARK4 mutation) to identify effects of SNCA gain of function as potential disease biomarkers. Downregulation of complexin 1 (CPLX1) mRNA was correlated with genotype, but the expression of other Parkinson's disease genes was not. In global RNA-seq profiling of blood from presymptomatic PARK4 indviduals, bioinformatics detected significant upregulations for platelet activation, hemostasis, lipoproteins, endocytosis, lysosome, cytokine, Toll-like receptor signaling and extracellular pathways. In PARK4 platelets, stimulus-triggered degranulation was impaired. Strong SPP1, GZMH and PLTP mRNA upregulations were validated in PARK4. When analysing individuals with rapid eye movement sleep behavior disorder, the most specific known prodromal stage of general PD, only blood CPLX1 levels were altered. Validation experiments confirmed an inverse mutual regulation of SNCA and CPLX1 mRNA levels. In the 3'-UTR of the CPLX1 gene we identified a single nucleotide polymorphism that is significantly associated with PD risk. In summary, our data define CPLX1 as a PD risk factor and provide functional insights into the role and regulation of blood SNCA levels. The new blood biomarkers of PARK4 in this Turkish family might become useful for PD prediction.

α-Synuclein vaccination modulates regulatory T cell activation and microglia in the absence of brain pathology

Background

Passive and active immunization with α-synuclein has been shown to be neuroprotective in animal models of Parkinson’s disease. We have previously shown that vaccination with α-synuclein, long before α-synuclein-induced brain pathology, prevents striatal degeneration by inducing regulatory T cell infiltration in parenchyma and antibody deposition on α-synuclein overexpressing neurons. However, the effect of peripheral α-synuclein on the immune system is unknown, as are the mechanistic changes induced in the CD4 T cell population during successful neuroprotective animal studies. We have studied the changes induced by vaccination with α-synuclein in the CD4 T cell pool and its impact on brain microglia to understand the immune mechanisms behind successful vaccination strategies in Parkinson’s disease animal models.

Methods

Mice were immunized with WT or nitrated α-synuclein at a dose equivalent to the one used in our previous successful vaccination strategy and at a higher dose to determine potential dose-dependent effects. Animals were re-vaccinated 4 weeks after and sacrificed 5 days later. These studies were conducted in naive animals in the absence of human α-synuclein expression.

Results

The CD4 T cell response was modulated by α-synuclein in a dose-dependent manner, in particular the regulatory T cell population. Low-dose α-synuclein induced expansion of naive (Foxp3 + CCR6-CD127lo/neg) and dopamine receptor type D3+ regulatory T cells, as well as an increase in Stat5 protein levels. On the other hand, high dose promoted activation of regulatory T cells (Foxp3CCR6 + CD127lo/neg), which were dopamine receptor D2+D3-, and induced up-regulation of Stat5 and production of anti-α-synuclein antibodies. These effects were specific to the variant of α-synuclein used as the pathology-associated nitrated form induced distinct effects at both doses. The changes observed in the periphery after vaccination with low-dose α-synuclein correlated with an increase in CD154+, CD103+, and CD54+ microglia and the reduction of CD200R+ microglia. This resulted in the induction of a polarized tolerogenic microglia population that was CD200R-CD54CD103CD172a+ (82 % of total microglia).

Conclusions

We have shown for the first time the mechanisms behind α-synuclein vaccination and, importantly, how we can modulate microglia’s phenotype by regulating the CD4 T cell pool, thus shedding invaluable light on the design of neuroimmunoregulatory therapies for Parkinson’s disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0532-8) contains supplementary material, which is available to authorized users.

Autophagy of mitochondria: a promising therapeutic target for neurodegenerative disease

The autophagic process is the only known mechanism for mitochondrial turnover and it has been speculated that dysfunction of autophagy may result in mitochondrial error and cellular stress. Emerging investigations have provided new understanding of how autophagy of mitochondria (also known as mitophagy) is associated with cellular oxidative stress and its impact on neurodegeneration. This impaired autophagic function may be considered as a possible mechanism in the pathogenesis of several neurodegenerative disorders including Parkinson's disease, Alzheimer's disease, multiple sclerosis, amyotrophic lateral sclerosis, and Huntington disease. It can be suggested that autophagy dysfunction along with oxidative stress is considered main events in neurodegenerative disorders. New therapeutic approaches have now begun to target mitochondria as a potential drug target. This review discusses evidence supporting the notion that oxidative stress and autophagy are intimately associated with neurodegenerative disease pathogenesis. This review also explores new approaches that can prevent mitochondrial dysfunction, improve neurodegenerative etiology, and also offer possible cures to the aforementioned neurodegenerative diseases.

p53 signalling mediates acupuncture-induced neuroprotection in Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder associated with a selective loss of dopamine (DA) neurons in the substantia nigra of the midbrain. Recently, it has been demonstrated that acupuncture treatment has protective effects in PD. However, to date, the molecular mechanisms underlying acupuncture's effect on DA neuronal protection are largely unknown. In this study, we report that p53 signalling mediates the protective effects of acupuncture treatment in a mouse model of PD. We found that the acupuncture treatment in the mouse PD model results in significant recovery to the normal in the context of behaviour and molecular signatures. We found that the gene network associated with p53 signalling is closely involved in the protective effects of acupuncture treatment in PD. Consistent with this idea, we demonstrated that specific knockout of the p53 gene in the midbrain DA neurons abrogates the acupuncture induced protective effects in the mouse model of PD. Thus, these data suggest that p53 signalling mediates the protective effects of acupuncture treatment in PD.

Vaccination strategies for Parkinson disease: induction of a swift attack or raising tolerance?

Parkinson disease is the second most common neurodegenerative disease in the world, but there is currently no available cure for it. Current treatments only alleviate some of the symptoms for a few years, but they become ineffective in the long run and do not stop the disease. Therefore it is of outmost importance to develop therapeutic strategies that can prevent, stop, or cure Parkinson disease. A very promising target for these therapies is the peripheral immune system due to its probable involvement in the disease and its potential as a tool to modulate neuroinflammation. But for such strategies to be successful, we need to understand the particular state of the peripheral immune system during Parkinson disease in order to avoid its weaknesses. In this review we examine the available data regarding how dopamine regulates the peripheral immune system and how this regulation is affected in Parkinson disease; the specific cytokine profiles observed during disease progression and the alterations documented to date in patients' peripheral blood mononuclear cells. We also review the different strategies used in Parkinson disease animal models to modulate the adaptive immune response to salvage dopaminergic neurons from cell death. After analyzing the evidence, we hypothesize the need to prime the immune system to restore natural tolerance against α-synuclein in Parkinson disease, including at the same time B and T cells, so that T cells can reprogram microglia activation to a beneficial pattern and B cell/IgG can help neurons cope with the pathological forms of α-synuclein.

Neuroprotective effects of a variety of pomegranate juice extracts against MPTP-induced cytotoxicity and oxidative stress in human primary neurons

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is an environmental toxin which selectively induces oxidative damage and mitochondrial and proteasomal dysfunctions to dopaminergic neurons in the substantia nigra leading to Parkinsonian syndrome in animal models and humans. MPTP is one of the most widely used in vitro models to investigate the pathophysiology of Parkinson's disease (PD) and, screen for novel therapeutic compounds that can slow down or ameliorate this progressive degenerative disease. We investigated the therapeutic effect of pomegranate juice extracts (PJE), Helow, Malasi, Qusum, and Hamadh against MPTP-induced neurotoxicity in primary human neurons by examining extracellular LDH activity, intracellular NAD⁺ and ATP levels, and endogenous antioxidant levels including lipid peroxidation products, catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, and reduced glutathione (GSH) levels. MPTP induced a reduction in SOD and GPx activities and intracellular NAD⁺, ATP, and GSH levels parallel to an increase in extracellular LDH and CAT activities, although lipid peroxidation was not altered. We report that helow and malasi can ameliorate MPTP-induced neurotoxicity by attenuating the observed changes in redox function to a greater extent than qusum and hamedh. Selected PJE varieties may exhibit properties which may be of therapeutic value to slow down age-related degeneration and neurodegeneration in particular.

Mitochondria, oxidative stress and neurodegeneration

Mitochondria are involved in ATP supply to cells through oxidative phosphorylation (OXPHOS), synthesis of key molecules and response to oxidative stress, as well as in apoptosis. They contain many redox enzymes and naturally occurring inefficiencies of oxidative phosphorylation generate reactive oxygen species (ROS). CNS functions depend heavily on efficient mitochondrial function, since brain tissue has a high energy demand. Mutations in mitochondrial DNA (mtDNA), generation and presence of ROS and environmental factors may contribute to energy failure and lead to neurodegenerative diseases. Many rare metabolic disorders have been associated with mitochondrial dysfunction. More than 300 pathogenic mtDNA mutations involve proteins that regulate OXPHOS and mitochondrial structural integrity, and have also been described in neurodegenerative diseases with autosomal inheritance. Mitochondria may have an important role in ageing-related neurodegenerative disorders like Parkinson's disease (PD), Alzheimer's disease (AD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS). In primary mitochondrial and neurodegenerative disorders, there is strong evidence that mitochondrial dysfunction occurs early and has a primary role in pathogenesis. In the present review, we discuss several mitochondrial diseases as models of neurodegeneration.

Cytotoxicity effects of amiodarone on cultured cells

Amiodarone is a potent anti-arrhythmic drug used for the treatment of cardiac arrhythmias. Although, the effects of amiodarone are well characterized on post-ischemic heart and cardiomyocytes, its toxicity on extra-cardiac tissues is still poorly understood. To this aim, we have monitored the cytotoxicity effects of this drug on three cultured cell lines including hepatocytes (HepG2), epithelial cells (EAhy 926) and renal cells (Vero). We have investigated the effects of amiodarone on (i) cell viabilities, (ii) heat shock protein expressions (Hsp 70) as a parameter of protective and adaptive response and (iii) oxidative damage.Our results clearly showed that amiodarone inhibits cell proliferation, induces an over-expression of Hsp 70 and generates significant amount of reactive oxygen species as measured by lipid peroxidation occurrence. However, toxicity of amiodarone was significantly higher in renal and epithelial cells than in hepatocytes. Vitamin E supplement restores the major part of cell mortalities induced by amiodarone showing that oxidative damage is the predominant toxic effect of the drug.Except its toxicity for the cardiac system, our findings demonstrated that amiodarone can target other tissues. Therefore, kidneys present a high sensibility to this drug which may limit its use with subjects suffering from renal disorders.

Peripheral biomarkers of Parkinson's disease as early reporters of central neurodegeneration

Parkinson's disease (PD) is the most common age-related movement disorder, with a prevalence of approximately 2% among people over 65 years of age. The diagnosis of PD is currently based on the clinical manifestations of the disease; therefore, the availability of peripheral biomarkers would have a great impact. In this review, we discuss and compare several attempts made to find peripheral biomarkers of PD to achieve early diagnosis, differential diagnosis, therapy assessment and classification of disease subtypes. Several investigators focused on proteins that are involved in PD pathogenesis. However, the best choice for a sensible biomarker-discovery procedure makes use of global approaches such as metabolomics and proteomics. In addition, the tissue or compartment where biomarkers are located, plays a basic role. In this context, lymphocytes are of particular interest because they are circulating dopaminergic cells, and display several functional modifications in PD.

Lymphocyte proteomics of Parkinson’s disease patients reveals cytoskeletal protein dysregulation and oxidative stress

Aims: There is increasing evidence of biochemical alterations in peripheral blood lymphocytes of Parkinson’s disease (PD) patients. In this work, we describe the changes in protein levels in peripheral lymphocytes of PD patients in order to identify potential peripheral biomarkers. Materials & methods: By means of 2D electrophoresis and mass spectrometry protein identification, we compared patients under L-3,4-dihydroxyphenylalanine (L-DOPA) treatment, patients under subthalamic nucleus deep-brain stimulation and healthy controls. Results: Statistical analysis of the results demonstrated that cofilin-1, tropomyosin, and a specific actin isoform vary significantly in patients, regardless of the therapy. Two different isoforms of γ-fibrinogen either correlate with the disease state or with the disease duration. Eventually, specific changes associated with the different therapies allowed to highlight oxidative stress conditions in lymphocytes in patients treated with higher doses of L-DOPA. Conclusions: As a whole, peripheral blood lymphocytes are sensitive reporters of PD over inter-individual variability, and allow the identification of specific alterations that could be further exploited for diagnostic purposes.

Dopamine transporter immunoreactivity in peripheral blood lymphocytes in multiple system atrophy

Previous studies showed the reduction of dopamine transporter immunoreactivity (DAT-IR) in peripheral blood lymphocytes (PBL) in Parkinson's disease. Here we report the reduction of DAT-IR in PBL in the extrapyramidal variant of multiple system atrophy. These results suggest the reduction of DAT-IR in PBL in a variety of neurodegenerative disorders, provided the presence of damage of the central dopaminergic systems. The reduction of DAT-IR in PBL in these disorders may represent a compensatory phenomenon aimed at reducing intracellular dopamine influx and, consequently, dopamine-mediated aggravation of oxidative stress in these cells.

Central and peripheral dopamine transporter reduction in Parkinson's disease

OBJECTIVE

Previous reports showed the reduction of dopamine transporter immunoreactivity in peripheral blood lymphocytes in Parkinson's disease. In this work, we sought to investigate the possible correlation between central and peripheral dopamine transporter immunoreactivity values in a group of 11 drug-naive patients with Parkinson's disease.

METHODS

Densitometric measurements of dopamine transporter immunoreactivity in peripheral blood lymphocytes was accomplished as described recently, using a monoclonal antidopamine transporter antibody. Dopamine transporter binding in the caudate and putamen nuclei was measured by means of (123)I-fluopane single-photon emission computed tomography in the same patients.

RESULTS

The results failed to show any significant correlation between dopamine transporter immunoreactivity in peripheral blood lymphocytes and the caudate or putamen dopamine transporter binding. Moreover, dopamine transporter immunoreactivity in peripheral blood lymphocytes was reduced also in the single patient with normal striatal dopamine transporter binding.

DISCUSSION

These results indicate the lack of correlation between central and peripheral dopamine transporter reduction in Parkinson's disease, using the methodologies applied herein. They therefore suggest that the two phenomena are unlikely to share a common pathogenetic mechanism.