Parkinson disease: from pathology to molecular disease mechanisms

The Immunomodulary Effects of Systematic Exercise in Older Adults and People with Parkinson's Disease

We sought to investigate whether regular balance training of moderate intensity (BT) has an effect on changes in selected cytokines, neurotrophic factors, CD200 and fractalkine in healthy older adults and participants with Parkinson’s disease (PD). Sixty-two subjects were divided into groups depending on experimental intervention: (1) group of people with PD participating in BT (PDBT), (2) group of healthy older people participating in BT (HBT), (3,4) control groups including healthy individuals (HNT) and people with PD (PDNT). Blood samples were collected twice: before and after 12 weeks of balance exercise (PDBT, HBT), or 12 weeks apart (PDNT, HNT). The study revealed significant increase of interleukin10 (PDBT, p = 0.026; HBT, p = 0.011), β-nerve growth factor (HBT, p = 0.002; PDBT, p = 0.016), transforming growth factor-β1 (PDBT, p = 0.018; HBT, p < 0.004), brain-derived neurotrophic factor (PDBT, p = 0.011; HBT, p < 0.001) and fractalkine (PDBT, p = 0.045; HBT, p < 0.003) concentration only in training groups. In PDBT, we have found a significant decrease of tumor necrosis factor alpha. No training effect on concentration of interleukin6, insulin-like growth factor 1 and CD200 was observed in both training and control groups. Regular training can modulate level of inflammatory markers and induce neuroprotective mechanism to reduce the inflammatory response.

Pharmacological intervention of histone deacetylase enzymes in the neurodegenerative disorders

Reversal of aging symptoms and related disorders are the challenging task where epigenetic is a crucial player that includes DNA methylation, histone modification; chromatin remodeling and regulation that are linked to the progression of various neurodegenerative disorders (NDDs). Overexpression of various histone deacetylase (HDACs) can activate Glycogen synthase kinase 3 which promotes the hyperphosphorylation of tau and inhibits its degradation. While HDAC is important for maintaining the neuronal morphology and brain homeostasis, at the same time, these enzymes are promoting neurodegeneration, if it is deregulated. Different experimental models have also confirmed the neuroprotective effects caused by HDAC enzymes through the regulation of neuronal apoptosis, inflammatory response, DNA damage, cell cycle regulation, and metabolic dysfunction. Apart from transcriptional regulation, protein-protein interaction, histone post-translational modifications, deacetylation mechanism of non-histone protein and direct association with disease proteins have been linked to neuronal imbalance. Histone deacetylases inhibitors (HDACi) can be able to alter gene expression and shown its efficacy on experimental models, and in clinical trials for NDD's and found to be a very promising therapeutic agent with certain limitation, for instance, non-specific target effect, isoform-selectivity, specificity, and limited number of predicted biomarkers. Herein, we discussed (i) the catalytic mechanism of the deacetylation process of various HDAC's in in vivo and in vitro experimental models, (ii) how HDACs are participating in neuroprotection as well as in neurodegeneration, (iii) a comprehensive role of HDACi in maintaining neuronal homeostasis and (iv) therapeutic role of biomolecules to modulate HDACs.

Inhibitory potential of plant secondary metabolites on anti-Parkinsonian drug targets: Relevance to pathophysiology, and motor and non-motor behavioural abnormalities

Parkinson's disease (PD), a progressive neurodegenerative motor disorder, is caused due to the loss of dopaminergic neurons in the substantia nigra pars compacta region of mid-brain and the resultant depletion of the levels of the neurotransmitter dopamine. Although the pathophysiology of the disease is least understood, studies in animal models revealed oxidative stress, mitochondrial dysfunction and inflammation to be the major contributors. Dopamine replenishment therapy by oral administration of L-DOPA, the precursor of dopamine remains to be the therapeutic gold-standard for symptomatic treatment of PD. In addition, use of inhibitors of dopamine metabolizing enzymes (viz. monoamine oxidase-B: MAO-B; and catechol-O-methyltransferase: COMT) are the other strategies for amelioration of the motor abnormalities. Further, PD is associated with non-motor behavioural abnormalities as well, including cognitive impairment and mood disorders, which are caused due to cholinergic neurodegeneration, and thus inhibition of Acetylcholinesterase (AChE) is suggested. However, the currently used drugs against the three crucial enzymes (MAO-B, COMT and AChE) elicit several side effects, and thus the search for novel compounds continues, and plant-based compounds have promising potential in this regard. In the present study, we have used computational modeling to determine the efficiency of 40 plant-based natural products in inhibiting the three anti-Parkinsonian drug targets. Further, statistical analysis was performed to identify the properties of the compounds which are crucial for inhibition of the enzymes. While all the phytochemicals showed potential in inhibiting the enzymes, Rutin, Demethoxycurcumin and Acteoside were found to be most effective inhibitors of MAO-B, COMT and AChE respectively. Since most of the compounds are established anti-oxidant and anti-inflammatory molecules, they are surmised to confer neuroprotection in PD, and prevent progression of the disease.

Iron chelator Deferoxamine protects human neuroblastoma cell line SH-SY5Y from 6-Hydroxydopamine-induced apoptosis and autophagy dysfunction

BACKGROUND

Intracellular iron involves in Fenton's reaction-mediated Hydroxyl radical (OH·) generation by reacting with the neurotoxic agent 6-Hydroxydopamine (6-OHDA) autoxidation derivative Hydrogen Peroxide (H₂O₂). Several studies have been conducted so far on the neuroprotective activities of the iron chelator Deferoxamine (DFO) but little or no clear evidence about the underlying cellular mechanism is available.

METHODS

The present study was conducted on Human neuroblastoma cell line SH-SY5Y in the absence or presence of 6-OHDA or H₂O₂ and / or DFO. Following incubation, cell viability assay, intracellular reactive oxygen species (ROS) determination, flow cytometric quantification of apoptotic cells followed by nuclear staining, intracellular tracking of transfected fusion construct of microtubule-associated protein 1B-light chain with Green fluorescent protein - Red fluorescent protein (LC3B-GFP-RFP reporters) and immunocytochemistry of intracellular Cathepsin protein by confocal microscopy, were conducted. In addition, western blotting was carried out to detect expressions of apoptotic and autophagy related proteins.

RESULTS

This study confirmed the neuroprotective potential of DFO by inhibiting 6-OHDA-mediated cell death and ROS generation. Reduced percentage of apoptotic cells and appearance of altered nuclei architecture followed by a reduced expression of cleaved PARP (Poly-ADP-ribose Polymerase) and cleaved Caspase-3 were observed upon DFO treatment against 6-OHDA, and as well as against H₂O₂ in SH-SY5Y cell lines. Besides, DFO induced the intracellular autophagolysosome formation (red puncta) rather than autophagosome (yellow puncta) only. Thereafter it was observed that DFO restored the expression of intracellular lysosomal protease Cathepsin and reduced the expression of the LC3-II.

CONCLUSION

Taken together, this study clearly demonstrated that the anti-Fenton activity of DFO inhibited apoptosis and caused blockade in ALP or autophagy dysfunction in SH-SY5Y cell lines. These outcomes further suggest that DFO provides neuroprotection by inhibiting apoptosis and inducing the progression of Autophagy- lysosomal pathway (ALP).

A review of computational modeling and deep brain stimulation: applications to Parkinson's disease

Biophysical computational models are complementary to experiments and theories, providing powerful tools for the study of neurological diseases. The focus of this review is the dynamic modeling and control strategies of Parkinson's disease (PD). In previous studies, the development of parkinsonian network dynamics modeling has made great progress. Modeling mainly focuses on the cortex-thalamus-basal ganglia (CTBG) circuit and its sub-circuits, which helps to explore the dynamic behavior of the parkinsonian network, such as synchronization. Deep brain stimulation (DBS) is an effective strategy for the treatment of PD. At present, many studies are based on the side effects of the DBS. However, the translation from modeling results to clinical disease mitigation therapy still faces huge challenges. Here, we introduce the progress of DBS improvement. Its specific purpose is to develop novel DBS treatment methods, optimize the treatment effect of DBS for each patient, and focus on the study in closed-loop DBS. Our goal is to review the inspiration and insights gained by combining the system theory with these computational models to analyze neurodynamics and optimize DBS treatment.

Comprehensive Analysis of Neurotoxin-Induced Ablation of Dopaminergic Neurons in Zebrafish Larvae

Neurotoxin exposure of zebrafish larvae has been used to mimic a Parkinson’s disease (PD) phenotype and to facilitate high-throughput drug screening. However, the vulnerability of zebrafish to various neurotoxins was shown to be variable. Here, we provide a direct comparison of ablative effectiveness in order to identify the optimal neurotoxin-mediated dopaminergic (DAnergic) neuronal death in larval zebrafish. Transgenic zebrafish, Tg(dat:eGFP), were exposed to different concentrations of the neurotoxins MPTP, MPP⁺, paraquat, 6-OHDA, and rotenone for four days, starting at three days post-fertilization. The LC₅₀ of each respective neurotoxin concentration was determined. Confocal live imaging on Tg(dat:eGFP) showed that MPTP, MPP⁺, and rotenone caused comparable DAnergic cell loss in the ventral diencephalon (vDC) region while, paraquat and 6-OHDA caused fewer losses of DAnergic cells. These results were further supported by respective gene expression analyses of dat, th, and p53. Importantly, the loss of DAnergic cells from exposure to MPTP, MPP⁺, and rotenone impacted larval locomotor function. MPTP induced the largest motor deficit, but this was accompanied by the most severe morphological impairment. We conclude that, of the tested neurotoxins, MPP⁺ recapitulates a substantial degree of DAnergic ablation and slight locomotor perturbations without systemic defects indicative of a Parkinsonian phenotype.

Association between SNCA rs356220 polymorphism and Parkinson's disease: A meta-analysis

Several studies have investigated the correlation between single nucleotide polymorphism (SNP) rs356220 in the α-synuclein (SNCA) gene and Parkinson's disease (PD) with inconsistent results. Herein, a meta-analysis was conducted to ascertain the association of the SNCA rs356220 polymorphism with the risk of PD. Six eligible articles involving 5333 PD cases and 5477 controls were included in this meta-analysis. The pooled odds ratios (OR) and 95 % confidence interval (CI) were calculated to estimate the association. The fixed or random effect was selected based on the homogeneity among studies. Heterogeneity was detected by I². We performed sensitivity analysis to test the stablility of the results. Publication bias was evaluated by Funnel plot and Begg's test. The pooled results showed a significant association between SNCA rs356220 gene polymorphism and PD susceptibility in the codominant (FEM: OR = 1.31, 95 % CI = 1.24-1.39), dominant (FEM: OR = 1.38, 95 % CI = 1.27-1.49) and recessive (FEM: OR = 1.52, 95 % CI = 1.38-1.68) models. Furthermore, in the subgroup analysis stratified by ethnicity, increased risk of PD was identified in both Caucasian and Asian populations. Overall, the present meta-analysis provided evidence supporting that SNCA rs356220 polymorphism might act as a genetic susceptibility factor for PD.

ZPD-2, a Small Compound That Inhibits α-Synuclein Amyloid Aggregation and Its Seeded Polymerization

α-Synuclein (α-Syn) forms toxic intracellular protein inclusions and transmissible amyloid structures in Parkinson’s disease (PD). Preventing α-Syn self-assembly has become one of the most promising approaches in the search for disease-modifying treatments for this neurodegenerative disorder. Here, we describe the capacity of a small molecule (ZPD-2), identified after a high-throughput screening, to inhibit α-Syn aggregation. ZPD-2 inhibits the aggregation of wild-type α-Syn and the A30P and H50Q familial variants in vitro at substoichiometric compound:protein ratios. In addition, the molecule prevents the spreading of α-Syn seeds in protein misfolding cyclic amplification assays. ZPD-2 is active against different α-Syn strains and blocks their seeded polymerization. Treating with ZPD-2 two different PD Caenorhabditis elegans models that express α-Syn either in muscle or in dopaminergic (DA) neurons substantially reduces the number of α-Syn inclusions and decreases synuclein-induced DA neurons degeneration. Overall, ZPD-2 is a hit compound worth to be explored in order to develop lead molecules for therapeutic intervention in PD.

Anthraquinone from Edible Fungi Pleurotus ostreatus Protects Human SH-SY5Y Neuroblastoma Cells Against 6-Hydroxydopamine-Induced Cell Death-Preclinical Validation of Gene Knockout Possibilities of PARK7, PINK1, and SNCA1 Using CRISPR SpCas9

Parkinson's disease (PD) results from the degeneration of the nervous tissue brought about by ecological and hereditary components which affects nerve cells in the brain. It is the world's second most normal neurodegenerative issue, which can essentially weaken the personal satisfaction, make reliance, and trigger untimely mortality of affected people. The commonness pace of PD is 0.5-1% among individuals in the age group of 65-69 years and 1-3% among those 80 or more. Clinical appearances incorporate bradykinesia, tremors, unbending nature, and postural unsteadiness; spectrums of non-motor symptoms include psychological hindrance and passionate and behavioral brokenness. In this study, 6-OHDA-induced neurotoxicity was analyzed for various cytotoxicity analyses. The genes identified were PINK1 (PTEN-induced kinase 1), PARK7 (Parkinsonism-associated deglycase) and SNCA 1 (alpha synuclein1) validated using CRISPR spcas9 genome editing tool. In this study, Anthraquinone isolated from Pleurotus ostreatus was treated against a dopaminergic neurotoxin, 6-hydroxydopamine (6-OHDA), which induced neurotoxicity in SH-SY5Y cells. Experimental groups in SH-SY5Y neuroblastoma cells were treated with anthraquinone (50 nM) and 6-OHDA (100 nM). MTT and ROS assays were performed to assess the cell viability and oxidative stress within the cells, followed by mixed-member proportional (Mitochondrial membrane potential), dual staining, and immunoblotting. 6-OHDA-induced cell death in SH-SY5Y cells was dose-dependently attenuated by treatment with anthraquinone. The genes responsible for mutation were studied and the mutated RNAs knockout possibilities was studied using CRISPR spcas9 genome editing tool. Treatment with anthraquinone attenuated the level of oxidative stress and reduced the mitochondrial dysfunction associated with 6-OHDA treatment. Immunoblot analysis carried out with apoptotic markers showed that cytochrome C and caspase-3 expression increased significantly in anthraquinone-treated cells, whereas 6-OHDA-treated group showed a significant decrease when compared with an experimental control group. The mutated genes PARK7, PINK1, and SNCA1 were analyzed and found to exhibit four gene knock possibilities to treat PD. Reports demonstrate that other than following up on the biosynthesis of dopamine and its metabolites, these mixes counteract D2 receptors' extreme touchiness. It is proposed that further examinations need be directed to better understand the activity of the bioactive mixes circulated in these edible fungi Pleurotus ostreatus. The gene knockout possibilities identified by CRISPR SpCas9 will pave a way for better research for PD treatment.

SIRT3 Regulation of Mitochondrial Quality Control in Neurodegenerative Diseases

Neurodegenerative diseases are disorders that are characterized by a progressive decline of motor and/or cognitive functions caused by the selective degeneration and loss of neurons within the central nervous system. The most common neurodegenerative diseases are Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). Neurons have high energy demands, and dysregulation of mitochondrial quality and function is an important cause of neuronal degeneration. Mitochondrial quality control plays an important role in maintaining mitochondrial integrity and ensuring normal mitochondrial function; thus, defects in mitochondrial quality control are also significant causes of neurodegenerative diseases. The mitochondrial deacetylase SIRT3 has been found to have a large effect on mitochondrial function. Recent studies have also shown that SIRT3 has a role in mitochondrial quality control, including in the refolding or degradation of misfolded/unfolded proteins, mitochondrial dynamics, mitophagy, and mitochondrial biogenesis, all of which are affected in neurodegenerative diseases.

Critical Role of Oxidatively Damaged DNA in Selective Noradrenergic Vulnerability

An important pathology in Parkinson's disease (PD) is the earlier and more severe degeneration of noradrenergic neurons in the locus coeruleus (LC) than dopaminergic neurons in the substantia nigra. However, the basis of such selective vulnerability to insults remains obscure. Using noradrenergic and dopaminergic cell lines, as well as primary neuronal cultures from rat LC and ventral mesencephalon (VM), the present study compared oxidative DNA damage response markers after exposure of these cells to hydrogen peroxide (H₂O₂). The results showed that H₂O₂ treatment resulted in more severe cell death in noradrenergic cell lines SK-N-BE(2)-M17 and PC12 than dopaminergic MN9D cells. Furthermore, there were higher levels of oxidative DNA damage response markers in noradrenergic cells and primary neuronal cultures from the LC than dopaminergic cells and primary cultures from the VM. It included increased tail moments and tail lengths in Comet assay, and increased protein levels of phosphor-p53 and γ-H2AX after treatments with H₂O₂. Consistent with these measurements, exposure of SK-N-BE(2)-M17 cells to H₂O₂ resulted in higher levels of reactive oxygen species (ROS). Further experiments showed that exposure of SK-N-BE(2)-M17 cells to H₂O₂ caused an increased level of noradrenergic transporter, reduced protein levels of copper transporter (Ctr1) and 8-oxoGua DNA glycosylase, as well as amplified levels of Ca_v1.2 and Ca_v1.3 expression. Taken together, these experiments indicated that noradrenergic neuronal cells seem to be more vulnerable to oxidative damage than dopaminergic neurons, which may be related to the intrinsic characteristics of noradrenergic neuronal cells.

Peripheral Delivery of Neural Precursor Cells Ameliorates Parkinson's Disease-Associated Pathology

: Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by loss of motor control due to a wide loss of dopaminergic neurons along the nigro-striatal pathway. Some of the mechanisms that contribute to this cell death are inflammation, oxidative stress, and misfolded alpha-synuclein-induced toxicity. Current treatments are effective at managing the early motor symptoms of the disease, but they become ineffective over time and lead to adverse effects. Previous research using intracerebral stem cell therapy for treatment of PD has provided promising results; however, this method is very invasive and is often associated with unacceptable side effects. In this study, we used an MPTP-injected mouse model of PD and intravenously administered neural precursors (NPs) obtained from mouse embryonic and mesenchymal stem cells. Clinical signs and neuropathology were assessed. Female mice treated with NPs had improved motor function and reduction in the neuroinflammatory response. In terms of safety, there were no tumorigenic formations or any detectable adverse effect after treatment. Our results suggest that peripheral administration of stem cell-derived NPs may be a promising and safe therapy for the recovery of impaired motor function and amelioration of brain pathology in PD.

Autophagic- and Lysosomal-Related Biomarkers for Parkinson's Disease: Lights and Shadows

Parkinson’s disease (PD) is a neurodegenerative disorder that currently affects 1% of the population over the age of 60 years, for which no disease-modifying treatments exist. This lack of effective treatments is related to the advanced stage of neurodegeneration existing at the time of diagnosis. Thus, the identification of early stage biomarkers is crucial. Biomarker discovery is often guided by the underlying molecular mechanisms leading to the pathology. One of the central pathways deregulated during PD, supported both by genetic and functional studies, is the autophagy-lysosomal pathway. Hence, this review presents different studies on the expression and activity of autophagic and lysosomal proteins, and their functional consequences, performed in peripheral human biospecimens. Although most biomarkers are inconsistent between studies, some of them, namely HSC70 levels in sporadic PD patients, and cathepsin D levels and glucocerebrosidase activity in PD patients carrying GBA mutations, seem to be consistent. Hence, evidence exists that the impairment of the autophagy-lysosomal pathway underlying PD pathophysiology can be detected in peripheral biosamples and further tested as potential biomarkers. However, longitudinal, stratified, and standardized analyses are needed to confirm their clinical validity and utility.

Neuroprotective Effect of Quercetin in Combination with Piperine Against Rotenone- and Iron Supplement-Induced Parkinson's Disease in Experimental Rats

Parkinson's disease (PD) is a neurodegenerative disorder caused by selective dopaminergic neuronal loss. Rotenone is a neurotoxin that selectively destroys dopaminergic neurons, leading to PD-like symptoms. Quercetin possesses antioxidant, anti-inflammatory, and neuroprotective properties but a major drawback is its low bioavailability. Therefore, the present study was designed to evaluate the neuroprotective effect of quercetin in combination with piperine against rotenone- and iron supplement-induced model of PD. Rotenone was administered at a dose of 1.5 mg/kg through an intraperitoneal route with iron supplement at a dose of 120 μg/g in diet from day 1 to day 28. Pre-treatment with quercetin (25 and 50 mg/kg, p.o.), piperine (2.5 mg/kg, p.o.) alone, quercetin (25 mg/kg, p.o.) in combination with piperine (2.5 mg/kg), and ropinirole (0.5 mg/kg, i.p.) was administered for 28 days 1 h prior to rotenone and iron supplement administration. All behavioral parameters were assessed on weekly basis. On the 29th day, all animals were sacrificed and striatum was isolated for biochemical (LPO, nitrite, GSH, mitochondrial complexes I and IV), neuroinflammatory (TNF-α, IL-1β, and IL-6), and neurotransmitter (dopamine, norepinephrine, serotonin, GABA, glutamate) estimation. Quercetin treatment attenuated rotenone- and iron supplement-induced motor deficits and biochemical and neurotransmitter alterations in experimental rats. However, combination of quercetin (25 mg/kg) with piperine (2.5 mg/kg) significantly enhanced its neuroprotective effect as compared with treatment with quercetin alone. The study concluded that combination of quercetin with piperine contributed to superior antioxidant, anti-inflammatory, and neuroprotective effect against rotenone- and iron supplement-induced PD in experimental rats.

Luteolin-7-O-glucoside protects dopaminergic neurons by activating estrogen-receptor-mediated signaling pathway in MPTP-induced mice

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative disorder that is characterized by the degeneration of dopaminergic neurons in substantia nigra (SN). Accumulating evidences implicate the beneficial role of estrogen in the therapy of PD.

METHODS

In the present study, the protective function of luteolin-7-O-glucoside (LUT-7G), a natural flavonoid, was investigated in 1-methyl-4-phenylpyridinium (MPP⁺) treated SH-SY5Y cells and 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) induced mice.

RESULTS

Pre-treatment of LUT-7G increased the viability and reduced the apoptosis of SH-SY5Y cells treated by MPP⁺. At molecular level, the Bcl-2/Bax ratio was increased, while the expression of cleaved caspase 3 was markedly lessened. Moreover, LUT-7G increased the expression of estrogen receptor (ER), ERα and ERβ, and enhanced the activation of ERK1/2/STAT3/c-Fos that could be abolished by ER antagonists. Furthermore, in vivo experiment indicated that pre-treatment of LUT-7G improved the bradykinesia, and enhanced the muscle strength as well as the balancing capacity of mice treated with MPTP. And LUT-7G prevented the injury of TH positive cells in substantia nigra and increased TH positive nerve fibers in striatum. In addition, pre-treatment of LUT-7G also significantly diminished the MPTP-induced gliosis in substantia nigra.

CONCLUSIONS

LUT-7G effectively protected dopaminergic neurons against MPP⁺ or MPTP-induced toxicity, probably by activating the ER-mediated signaling pathway. Our findings explore the therapeutic potential of LUT-7G for PD therapy.

Han Chinese family with early-onset Parkinson's disease carries novel compound heterozygous mutations in the PARK2 gene

PURPOSE

To identify deletions, duplications, and point mutations in 55 previously reported genes associated with Parkinson's disease (PD) and certain genes associated with tremor, spinocerebellar ataxia, and dystonia in a Han Chinese pedigree with early-onset Parkinson's disease (EOPD).

PATIENTS AND METHODS

Clinical examinations and genomic analyses were performed on six subjects belonging to three generations of a Han Chinese family. Target region capture and high-throughput sequencing were used to screen these genes associated with PD, tremor, spinocerebellar ataxia, and dystonia. The multiplex ligation-dependent probe amplification (MLPA) method was applied to detect rearrangements in PARK2 exons. Direct Sanger sequencing of samples from all subjects further verified the detected abnormal PRKRA, SPTBN2, and ATXN2 gene fragments.

RESULTS

Two family members were diagnosed with PD based on the clinical manifestations, imaging analyses. PARK2 gene heterozygous deletion of exon 3 and heterozygous duplication of exon 6 were identified in them (II-3 and 4). A single heterozygous deletion of exon 3 in PARK2 was detected in II-5 and III-10. A single duplication of exon 6 in PARK2 was detected in I1. Both the heterozygous mutation c.2834G>A (p. R945H) in exon 16 and the heterozygous mutation c.1924 C>T (p. R642W) in exon 14 of the SPTBN2 gene were identified in II-3, II-4, and III-10. The heterozygous mutation c.2989 C>T (p. R997X) in exon 24 of the ATXN2 gene was detected in II-4 and II-5, and the heterozygous mutation c.170 C>A (p. S57Y) in exon 2 of the PRKRA gene was detected in II-3, II-4, and III-10. Other mutations in some genes associated with PD, tremor, spinocerebellar ataxia, and dystonia were not detected.

CONCLUSIONS

Novel compound heterozygous mutations were identified in a Han Chinese pedigree and might represent a cause of EOPD.

Chloramphenicol Mitigates Oxidative Stress by Inhibiting Translation of Mitochondrial Complex I in Dopaminergic Neurons of Toxin-Induced Parkinson's Disease Model

Paraquat (PQ), an herbicide considered an environmental contributor to the development of Parkinson's disease (PD), induces dopaminergic neuronal loss through reactive oxygen species (ROS) production and oxidative stress by mitochondrial complex I. Most patients with PQ-induced PD are affected by chronic exposure and require a preventive strategy for modulation of disease progression. To identify drugs that are effective in preventing PD, we screened more than 1000 drugs that are currently used in clinics and in studies employing PQ-treated cells. Of these, chloramphenicol (CP) showed the most powerful inhibitory effect. Pretreatment with CP increased the viability of PQ-treated SN4741 dopaminergic neuronal cells and rat primary cultured dopaminergic neurons compared with control cells treated with PQ only. CP pretreatment also reduced PQ-induced ROS production, implying that mitochondrial complex I is a target of CP. This effect of CP reflected downregulation of the mitochondrial complex I subunit ND1 and diminished PQ recycling, a major mechanism of ROS production, and resulted in the prevention of cell loss. Notably, these effects of CP were not observed in rotenone-pretreated SN4741 cells and Rho-negative cells, in which mitochondrial function is defective. Consistent with these results, CP pretreatment of MPTP-treated PD model mice also ameliorated dopaminergic neuronal cell loss. Our findings indicate that the inhibition of mitochondrial complex I with CP protects dopaminergic neurons and may provide a strategy for preventing neurotoxin-induced PD.

An omics-based strategy using coenzyme Q10 in patients with Parkinson's disease: concept evaluation in a double-blind randomized placebo-controlled parallel group trial

BACKGROUND

This study focuses on genetically stratified subgroups of Parkinson's disease patients (PD) with an enrichment of risk variants in mitochondrial genes,who might benefit from treatment with the "mitochondrial enhancer" coenzyme Q10 (156 mg coenzyme Q10/d [QuinoMit Q10® Fluid] over six months). The study will be performed in a double-blind, randomized, and placebo-controlled parallel group manner.

METHODS

PD patients will be specifically identified and assigned to treatment groups stratified by their genetic "mitochondrial risk burden" and consequently expected mitochondrial dysfunction and treatment response to coenzyme Q10 (homozygous or compound heterozygous Parkin/PINK1 mutation carriers [P++], heterozygous Parkin/PINK1 mutation carriers [P+], "omics" positive [omics+], and "omics" negative PD patients [omics-]). The primary endpoint is the change in motor symptoms over six months (as measured by the change in the motor subscore of the MDS-UPDRS). Secondary clinical endpoints include motor fluctuations, non-motor symptoms, results of magnetic resonance imaging of brain energy metabolism (31P-magnetic resonance spectroscopy imaging), and changes in structural and functional brain anatomy (MRI).

PERSPECTIVE

This study may be a first step towards a successful prediction of treatment response based on the genetic status of PD patients and translate progress in molecular genetics into personalized patient care. Further, magnetic resonance spectroscopy imaging may help quantify increased energy supply objectively and within a brief time after the start of treatment. Therefore, the potential of MRSI also for other studies addressing brain energy metabolism may will be assessed.

TRIAL REGISTRATION

This study was registered at the German Clinical Trial Registry (DRKS, DRKS00015880) on November 15th, 2018.

Role of PGC-1α in Mitochondrial Quality Control in Neurodegenerative Diseases

As one of the major cell organelles responsible for ATP production, it is important that neurons maintain mitochondria with structural and functional integrity; this is especially true for neurons with high metabolic requirements. When mitochondrial damage occurs, mitochondria are able to maintain a steady state of functioning through molecular and organellar quality control, thus ensuring neuronal function. And when mitochondrial quality control (MQC) fails, mitochondria mediate apoptosis. An apparently key molecule in MQC is the transcriptional coactivator peroxisome proliferator activated receptor γ coactivator-1α (PGC-1α). Recent findings have demonstrated that upregulation of PGC-1α expression in neurons can modulate MQC to prevent mitochondrial dysfunction in certain in vivo and in vitro aging or neurodegenerative encephalopathy models, such as Huntington's disease, Alzheimer's disease, and Parkinson's disease. Because mitochondrial function and quality control disorders are the basis of pathogenesis in almost all neurodegenerative diseases (NDDs), the role of PGC-1α may make it a viable entry point for the treatment of such diseases. This review focuses on multi-level MQC in neurons, as well as the regulation of MQC by PGC-1α in these major NDDs.

The impact of histone post-translational modifications in neurodegenerative diseases

Every year, neurodegenerative disorders take more than 5000 lives in the US alone. Cures have not yet been found for many of the multitude of neuropathies. The majority of amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD) and Parkinson's disease (PD) cases have no known genetic basis. Thus, it is evident that contemporary genetic approaches have failed to explain the etiology or etiologies of ALS/FTD and PD. Recent investigations have explored the potential role of epigenetic mechanisms in disease development. Epigenetics comprises heritable changes in gene utilization that are not derived from changes in the genome. A main epigenetic mechanism involves the post-translational modification of histones. Increased knowledge of the epigenomic landscape of neurodegenerative diseases would not only further our understanding of the disease pathologies, but also lead to the development of treatments able to halt their progress. Here, we review recent advances on the association of histone post-translational modifications with ALS, FTD, PD and several ataxias.

Role of Cardiolipin in Mitochondrial Function and Dynamics in Health and Disease: Molecular and Pharmacological Aspects

In eukaryotic cells, mitochondria are involved in a large array of metabolic and bioenergetic processes that are vital for cell survival. Phospholipids are the main building blocks of mitochondrial membranes. Cardiolipin (CL) is a unique phospholipid which is localized and synthesized in the inner mitochondrial membrane (IMM). It is now widely accepted that CL plays a central role in many reactions and processes involved in mitochondrial function and dynamics. Cardiolipin interacts with and is required for optimal activity of several IMM proteins, including the enzyme complexes of the electron transport chain (ETC) and ATP production and for their organization into supercomplexes. Moreover, CL plays an important role in mitochondrial membrane morphology, stability and dynamics, in mitochondrial biogenesis and protein import, in mitophagy, and in different mitochondrial steps of the apoptotic process. It is conceivable that abnormalities in CL content, composition and level of oxidation may negatively impact mitochondrial function and dynamics, with important implications in a variety of pathophysiological situations and diseases. In this review, we focus on the role played by CL in mitochondrial function and dynamics in health and diseases and on the potential of pharmacological modulation of CL through several agents in attenuating mitochondrial dysfunction.

Parkinson's Disease and Parkinsonism

Parkinson's disease is a progressive neurodegenerative disease characterized by tremor and bradykinesia and is a common neurologic ailment. Male sex and advancing age are independent risk factors and, as the population ages, is taking an increasing toll on productivity and medical resources. There are a number of other extrapyramidal conditions that can make the diagnosis challenging. Unlike other neurodegenerative diseases, idiopathic Parkinson's disease has effective treatments that mitigate symptoms. Medications can improve day-to-day function and, in cases where medication does not give a sustained benefit or has significant side effects, treatments like deep brain stimulation result in improved quality of life.

Generation of functional dopaminergic neurons from human spermatogonial stem cells to rescue parkinsonian phenotypes

Background

Recent progress in the induced generation of dopaminergic (DA) neurons from different types of stem cells or reprogrammed somatic cells holds tremendous potential for the treatment of Parkinson’s disease (PD). However, the lack of a reliable source for cell replacement therapy remains a major limitation in the treatment of human neurological disorders. Additionally, the current protocols for in vitro differentiation or cell reprogramming to generate human DA neurons are laborious, time-consuming, and expensive, and efficient conversion of human spermatogonial stem cells (hSSCs) to functional DA neurons has not yet been achieved.

Methods

Primary hSSCs from testicular tissues of patients were exposed to an improved induction system, which consisted mainly of olfactory ensheathing cell conditioned culture medium (OECCM) and a set of defined cell-extrinsic factors and small molecules. Morphological changes were assessed, along with the expression of various DA neuron phenotypic markers (e.g., Tuj-1, TH, Nurr1, DAT) and several critical pro-DA neurogenesis effectors (e.g., EN-1, Pitx3, Foxa2, Lmx1a, Lmx1b, and OTX2). In addition, transcriptome analysis was used to further evaluate the genetic similarity between the artificially differentiated DA neurons and genuine ones. Concomitantly, the functional properties of converted DA neurons including synapse formation, dopamine release, electrophysiological activity, and neuron-specific Ca²⁺ signaling images were determined. Finally, hSSCs in the early stage of induction were evaluated for survival, differentiation, migration, tumorigenicity in the mouse striatum, and improvement of functional deficits in MPTP-induced PD animals.

Results

The hSSC-derived neurons not only acquired neuronal morphological features but also expressed various phenotypic genes and protein characteristic of DA neurons and several effectors critical for pro-DA neurogenesis. Strikingly, as the period of induction was prolonged, expression of the critical molecules for DA neuron epigenetic status gradually increased while hSSC-specific markers sharply decreased. After 3 weeks of induction, the transdifferentiation efficiency reached 21%. In addition, hierarchical clustering analysis showed that the differentiated DA neurons closely resembled genuine ones. Furthermore, the hSSC-derived neurons gained sophisticated functional properties of wild-type DA neurons, and pro-induced hSSCs efficiently survived, migrated, and differentiated into DA neurons without tumorigenesis after transplantation into mouse striatum, leading to improvement of functional deficits in PD animals.

Conclusions

The results showed that, using the present improved straightforward approach, hSSCs could acquire DA neuron morphological features and functional properties and rescue parkinsonian phenotypes. Our strategy for the conversion of hSSCs into DA neurons is very efficient and thus may provide an alternative approach suitable for clinical cell therapy to treat neurodegenerative diseases including PD.

Metabolomics-driven identification of adenosine deaminase as therapeutic target in a mouse model of Parkinson's disease

Neuroinflammation is one of the driving forces of progressive neurodegeneration in Parkinson's disease (PD). The metabolomics approach has been proved highly useful in identifying potential therapeutic targets. Here, to identify inflammation-relevant treatment targets for PD, mass spectrometry-based untargeted metabolomics was applied to characterize metabolic changes in the striatum of mice with double-hit PD induced by lipopolysaccharide plus 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Seven days after the final MPTP administration, metabolites from the purine metabolism pathway, including adenosine, 1-methyladenosine, adenine, inosine, hypoxanthine, xanthine, xanthosine, and guanosine, were found to be significantly dysregulated. The metabolite-protein interaction network and changes in the concentration ratio of these metabolites indicated that adenosine and adenosine deaminase (ADA; EC 3.5.4.4) were the most promising therapeutic targets and adenosine augmentation might be a rational approach to slow PD progression. These findings were then verified in a subacute MPTP-induced PD mouse model treated with ADA inhibition alone or in conjunction with antagonism of adenosine A_2A receptors (A_2A R). Behavioral, biochemical, and immunohistochemical analysis demonstrated that ADA inhibition significantly ameliorated the MPTP-mediated motor disabilities, dopamine depletion, and dopaminergic cell death. Significantly enhanced neuroprotective effects were further observed when the ADA inhibitor was utilized in conjunction with an A_2A R antagonist. Together, our study indicated for the first time that ADA inhibitors protected against neurodegeneration induced by the neurotoxin MPTP, and ADA inhibitors in combination with A_2A R antagonists showed additive antiparkinsonian effects.

NEAT1 regulates MPP+-induced neuronal injury by targeting miR-124 in neuroblastoma cells

Long non-coding RNAs (lncRNAs) have been reported to play important roles in Parkinson's disease (PD) pathogenesis. It was indicated that lncRNA nuclear enriched abundant transcript 1 (NEAT1) is involved in PD. However, the underlying mechanism of NEAT1 is still not fully explored. Human neuroblastoma cell line SH-SY5Y was treated with 1-Methyl-4-phenylpyridinium (MPP⁺) to mimic PD model in vitro. qRT-PCR was employed to detect the expression of NEAT1, IL-1β, IL-6 and TNF-α. Starbase database, RNA pull-down assay and RNA immunoprecipitation (RIP) assay were performed to verify the relationship between NEAT1 and miR-124. MTT assay and flow cytometry assay were used to detect cell viability and apoptosis. Elisa was introduced to measure the levels of IL-1β, IL6 and TNF-α in culture media. We found that NEAT1 expression was significantly increased in SH-SY5Y cells after MPP⁺ treatment in dose- and time- dependent manners. MPP⁺ induced the expression and secretion of IL-1β, IL-6 and TNF-α, inhibited cell viability and induced apoptosis while these effects could be rescued by NEAT1 silencing. miR-124 was a target of NEAT1. Anti-miR-124 could reverse the effects caused by NEAT1 knockdown in MPP⁺ treated SH-SY5Y cells. Therefore, we speculated that NEAT1 may regulate MPP⁺ induced neuronal injury by targeting miR-124 in SH-SY5Y cells.

The role of dispositional mindfulness in a stress-health pathway among Parkinson's disease patients and caregiving partners

PURPOSE

Parkinson's disease (PD) patients and their caregivers experience significant distress that impacts physical, emotional and social functioning in the patient, and in turn, has a significant impact on the caregiver. Lower levels of stress have been associated with a better prognosis in PD. The quality of dispositional mindfulness-innate present moment, non-judgmental awareness-has consistently been associated with less perceived stress, greater well-being, and better physical health in both clinical and healthy populations. To date, associations of mindfulness with distress, depression, sleep problems, and other variables that define health-related quality of life have not been examined in the context of PD patient/caregiver dyads.

METHODS

We investigated the impact of dispositional mindfulness in a stress-health model among eighteen dyads consisting of PD patients and their caregivers.

RESULTS

Multilevel linear modeling (actor-partner interdependence models) revealed significant associations between dispositional mindfulness and stress appraisal, interpersonal support, depressive symptoms, sleep, and health-related quality of life (HRQOL) within both dyadic partners. As expected, results demonstrated significant associations of distress with interpersonal support, depressive symptoms, sleep and HRQOL for both PD patients and caregivers.

CONCLUSIONS

Dispositional mindfulness was associated with reduced distress and its downstream clinical consequences. These results support an ameliorative role for dispositional mindfulness among PD patients and caregivers, as a protective factor against psychosocial burdens imposed on couples related to disease and caregiving. Findings suggest future studies should explore mindfulness training as a therapeutic option.

Effects of inspiratory muscle training on respiratory muscle strength, lung function, functional capacity and cardiac autonomic function in Parkinson's disease: Randomized controlled clinical trial protocol

BACKGROUND

Individuals with Parkinson's disease (PD), in addition to motor impairment, may evolve with respiratory and autonomic nervous system disorders. Currently, there are few studies with emphasis on muscle and pulmonary dysfunction and that verify the benefits of inspiratory muscle training (IMT) in this population.

AIM

The aim of this study was to evaluate whether IMT is effective for the improvement of respiratory muscle strength, lung function, thoracic mobility, functional capacity and cardiac autonomic function in PD.

METHODS

A randomized and controlled trial will be conducted with 26 participants with idiopathic PD, with aged between 50 and 65 years, in the Stages I to III by the Modified Hoehn and Yahr Scale. Respiratory muscle strength will be performed by manovacuometry and lung function by spirometry. Functional capacity will be evaluated by the 6-min walk test and autonomic cardiac function by heart rate variability. In addition, thoracic mobility measurement will also be performed. After the evaluations, these participants will be randomly assigned to two groups: the IMT group with Powerbreathe^® , which will perform the eight series of 2 min each, with 1 min of rest between them, totaling 30 min, at 60% of the maximum inspiratory pressure and the control group, who will perform the same training protocol but with the load maintained at 9 cmH₂ O. All participants will be submitted to the same motor training protocol.

CONCLUSION

It is expected that IMT increases the inspiratory muscle strength, contributing to the improved expiratory muscle strength, lung function, thoracic mobility, functional capacity and cardiac autonomic function in individuals with mild to moderate PD.

Electro-Acupuncture Ameliorated MPTP-Induced Parkinsonism in Mice via TrkB Neurotrophic Signaling

Neurotrophins, such as brain-derived neurotrophic factor (BDNF), have shown promise as neuroprotective agents, indicating their potential in therapeutic strategies for neurodegenerative disease. However, the inherent bioactivity and pharmaceutical limitations of BDNF compromise its clinical efficacy. Research has documented the beneficial effects of electroacupuncture (EA) against neurodegeneration, possibly by BDNF-mediated mechanisms. The present study was designed to clarify whether EA can mount a neuroprotective effect in mice lesioned with MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) via stimulation of the BDNF-TrkB signaling pathway. We found that EA not only ameliorated the motor dysfunction but also restored the dopaminergic neuronal function and upregulated BDNF expression in MPTP-lesioned mice. Interestingly, the TrkB inhibitor K252a abolished the neuroprotective effects of EA. Western blot analyses further demonstrated that EA might recover the level of phospho-Akt, phospho-ERK1/2, and BDNF against MPTP neurotoxicity via reversing the imbalance between TrkB FL and TrkB T1. Taken together, the results of the present study show that EA stimulation can ameliorate MPTP-induced parkinsonism in mice. Such a neuroprotective effect may be partially mediated via restoring TrkB neurotrophic signaling.

An in silico investigation on the inhibitory potential of the constituents of Pomegranate juice on antioxidant defense mechanism: Relevance to neurodegenerative diseases

Elevation in the levels of reactive oxygen and nitrogen species (RONS), and downregulation of cellular antixoidants, have ubiquitously been reported from studies in animal models of neurodegenerative diseases, including Parkinson’s disease (PD) and Alzheimer’s disease (AD). Thus, plant-derived compounds are widely being investigated for their beneficial effects in these models. However, while studies have reported antioxidant potentials of several phytochemicals, a large number of studies have demonstrated different phytochemicals to be rather pro-oxidant and exaggerate oxidative stress (OS). One such study aimed to investigate possible ameliorative effect of Pomegranate juice (PJ) in rat model of toxin-induced parkinsonism revealed that PJ exacerbates OS, inflammation and promotes neurodegeneration. Thus, it remains to be investigated whether different constituents and metabolites of PJ are pro-oxidant or anti-oxidant. Using computational modeling, we investigated possible inhibitory potential of different constituents of PJ and their metabolites viz. delphinidin-3-glucoside, dimethylellagic acid-glucuronide, ellagic acid, ellagitannin, gallic acid, gallotannin 23, pelargonidin, punicalagin, urolithin A, urolithin A-glucuronide and urolithin B, on anti-oxidant defense system of the brain. The results indicate that the constituents of PJ have the potential to inhibit five key enzymes of the neuronal antioxidant defense system, viz. catalase, superoxide dismutase, glutathione peroxidase 4, glutathione reductase and glutathione-S-transferase. Thus, it is surmised that the constituents of PJ may contribute to OS and neurodegeneration by way of affecting antioxidant defense mechanism. This may particularly be more pronounced in neurodegenerative diseases, since neurons are known to be more vulnerable to OS. Thus, the present findings caution the use of PJ in patients prone to OS, especially those suffering from neurodegenerative diseases, and warrant further experimental studies to unveil the effects of individual components and metabolites of PJ on antioxidant defense system of brain.

Earliest Mechanisms of Dopaminergic Neurons Sufferance in a Novel Slow Progressing Ex Vivo Model of Parkinson Disease in Rat Organotypic Cultures of Substantia Nigra

The current treatments of Parkinson disease (PD) are ineffective mainly due to the poor understanding of the early events causing the decline of dopaminergic neurons (DOPAn). To overcome this problem, slow progressively degenerating models of PD allowing the study of the pre-clinical phase are crucial. We recreated in a short ex vivo time scale (96 h) all the features of human PD (needing dozens of years) by challenging organotypic culture of rat substantia nigra with low doses of rotenone. Thus, taking advantage of the existent knowledge, the model was used to perform a time-dependent comparative study of the principal possible causative molecular mechanisms undergoing DOPAn demise. Alteration in the redox state and inflammation started at 3 h, preceding the reduction in DOPAn number (pre-diagnosis phase). The number of DOPAn declined to levels compatible with diagnosis only at 12 h. The decline was accompanied by a persistent inflammation and redox imbalance. Significant microglia activation, apoptosis, a reduction in dopamine vesicle transporters, and the ubiquitination of misfolded protein clearance pathways were late (96 h, consequential) events. The work suggests inflammation and redox imbalance as simultaneous early mechanisms undergoing DOPAn sufferance, to be targeted for a causative treatment aimed to stop/delay PD.

MicroRNA-26a/Death-Associated Protein Kinase 1 Signaling Induces Synucleinopathy and Dopaminergic Neuron Degeneration in Parkinson's Disease

BACKGROUND

Death-associated protein kinase 1 (DAPK1) is a widely distributed serine/threonine kinase that is critical for cell death in multiple neurological disorders, including Alzheimer's disease and stroke. However, little is known about the role of DAPK1 in the pathogenesis of Parkinson's disease (PD), the second most common neurodegenerative disorder.

METHODS

We used Western blot and immunohistochemistry to evaluate the alteration of DAPK1. Quantitative polymerase chain reaction and fluorescence in situ hybridization were used to analyze the expression of microRNAs in PD mice and patients with PD. Rotarod, open field, and pole tests were used to evaluate the locomotor ability. Immunofluorescence, Western blot, and filter traps were used to evaluate synucleinopathy in PD mice.

RESULTS

We found that DAPK1 is posttranscriptionally upregulated by a reduction in microRNA-26a (miR-26a) caused by a loss of the transcription factor CCAAT enhancer-binding protein alpha. The overexpression of DAPK1 in PD mice is positively correlated with neuronal synucleinopathy. Suppressing miR-26a or upregulating DAPK1 results in synucleinopathy, dopaminergic neuron cell death, and motor disabilities in wild-type mice. In contrast, genetic deletion of DAPK1 in dopaminergic neurons by crossing DAT-Cre mice with DAPK1 floxed mice effectively rescues the abnormalities in mice with chronic MPTP treatment. We further showed that DAPK1 overexpression promotes PD-like phenotypes by direct phosphorylation of α-synuclein at the serine 129 site. Correspondingly, a cell-permeable competing peptide that blocks the phosphorylation of α-synuclein prevents motor disorders, synucleinopathy, and dopaminergic neuron loss in the MPTP mice.

CONCLUSIONS

miR-26a/DAPK1 signaling cascades are essential in the formation of the molecular and cellular pathologies in PD.

Chronic renal dysfunction, proteinuria, and risk of Parkinson's disease in the elderly

BACKGROUND

The roles of chronic kidney disease and proteinuria in the development of Parkinson's disease have not been widely studied. The objective of this study was to examine the associations of chronic renal dysfunction and proteinuria with the risk of PD in older adults using cohort data of the whole South Korean population.

METHODS

We included 3,580,435 individuals aged ≥65 years who had undergone health checkups provided by the National Health Insurance Service of South Korea between 2009 and 2012 and were followed until 2015. Multivariable Cox proportional hazards regression models were performed.

RESULTS

During a mean follow-up of 5.2 ± 1.3 years, 30,813 individuals (0.86% of the total population) developed PD. Lower estimated glomerular filtration rate and a higher degree of proteinuria on a dipstick test were associated with higher incidence probability of PD (log-rank P < 0.001). In Cox regression models, chronic renal dysfunction graded by estimated glomerular filtration rate (mL/min/1.73 m² ) was associated with increased risk of PD after adjusting for potential confounding variables; hazard ratio (95% confidence interval) was 1.13 (1.10-1.17) for estimated glomerular filtration rate 60-90, 1.36 (1.31-1.42) for estimated glomerular filtration rate 30-60, and 1.47 (1.32-1.63) for estimated glomerular filtration rate <30 (P for trend <0.001). Proteinuria ≥1+ was also associated with increased risk of PD development (hazard ratio, 1.12; 95% confidence interval, 1.06-1.18). Coexistence of chronic kidney disease and proteinuria showed an increased hazard ratio of 1.33 (95% confidence interval, 1.23-1.45) for PD occurrence.

CONCLUSIONS

Our findings suggest that chronic renal dysfunction and dipstick-positive proteinuria may be independent risk factors for the development of PD in older adults. © 2019 International Parkinson and Movement Disorder Society.

Evaluating the Potential of Portulaca oleracea L. for Parkinson's Disease Treatment Using a Drosophila Model with dUCH-Knockdown

Parkinson's disease (PD), which is characterized by the decreased motor function and the loss of dopaminergic neurons, is a common neurodegenerative disorder in elders. There have been numerous in vitro and in vivo models developed to study mechanisms of PD and screen potential drug. Recently, dUCH-knockdown Drosophila model has been established and showed potential for screening antioxidants for PD treatment. The dUCH-knockdown Drosophila model of PD mimics most of main PD pathologies such as dopaminergic neurons degeneration, locomotor dysfunction, and shortage of dopamine in the brain. Common purslane (Portulaca oleracea L.) is a nutritious vegetable containing a variety of antioxidants, levodopa, and dopamine, a neurotransmitter closely related to PD. Purslane has been reported to exert neuroprotective effects against several neurotoxins including rotenone and 6-OHDA in PD models. However, the recent data have not provided sufficient evidence for using purslane to treat PD or decelerate disease progression. Therefore, in this study, we utilized dUCH-knockdown fly to evaluate the capacity of purslane extracts for PD treatment. The results showed that purslane extracts improved locomotor ability in the larval stage and decelerated disease progression in the adult stage. Additionally, purslane extracts also reduced dopaminergic neuron degeneration. Taken together, our data strongly demonstrated that purslane extracts effectively rescued PD-like phenotypes in the fly model. This result contributed a foundation for further study on the application of purslane in PD treatment.

Garcinol, a multifaceted sword for the treatment of Parkinson's disease

Garcinol, the principal phytoconstituent of plants belonging to the genus Garcinia, is known for its anti-oxidant as well as anti-inflammatory properties, which can be extended to its possible neuroprotective role. Recent reports disseminate the capacity of garcinol to influence neuronal growth and survival, alter the neurochemical status in brain, as well as regulate memory and cognition. The concomitant neuro-rescue property of garcinol may render it as an effective compound in Parkinson's disease (PD) therapeutics since it is capable of ameliorating the related pathophysiological changes. Emerging pieces of evidence linking histone acetylation defects to the progression of neurodegenerative diseases provide an effective basis for targeting PD. Hyperacetylation of histones has been reported in Parkinsonian brain, which demands the use of pharmacological inhibitors of histone acetyltransferases (HAT). Garcinol serves as a potent natural HAT inhibitor and has unveiled promising results in molecular interaction studies against Monoamine oxidase B (MAO-B) and Catechol-O-Methyltransferase (COMT), as well as in L-DOPA induced dyskinesia. This review highlights the prospective implications of garcinol as a novel anti-Parkinsonian agent, and establishes a bridge between histone acetylation defects and the pathological aspects of PD.

Marine-Derived Natural Compounds for the Treatment of Parkinson's Disease

Parkinson’s disease (PD) is a neurodegenerative disorder caused by the loss of dopaminergic neurons, leading to the motor dysfunctions of patients. Although the etiology of PD is still unclear, the death of dopaminergic neurons during PD progress was revealed to be associated with the abnormal aggregation of α-synuclein, the elevation of oxidative stress, the dysfunction of mitochondrial functions, and the increase of neuroinflammation. However, current anti-PD therapies could only produce symptom-relieving effects, because they could not provide neuroprotective effects, stop or delay the degeneration of dopaminergic neurons. Marine-derived natural compounds, with their novel chemical structures and unique biological activities, may provide anti-PD neuroprotective effects. In this study, we have summarized anti-PD marine-derived natural products which have shown pharmacological activities by acting on various PD targets, such as α-synuclein, monoamine oxidase B, and reactive oxygen species. Moreover, marine-derived natural compounds currently evaluated in the clinical trials for the treatment of PD are also discussed.

Pretreatment with crocin along with treadmill exercise ameliorates motor and memory deficits in hemiparkinsonian rats by anti-inflammatory and antioxidant mechanisms

The motor symptoms of Parkinson's disease (PD) are preceded by non-motorized symptoms including memory deficits. Treatment with dopamine replacement medications, such as L-DOPA only control motor symptoms and does not meet the clinical challenges of the disease, such as dyskinesia, non-motor symptoms, and neuroprotection. The purpose of the current study was to examine the neuroprotective potential of crocin and physical exercise in an animal model of PD. Male Wistar rats ran on a horizontal treadmill and/or pretreated with crocin at a dose of 100 mg/kg. Then, 16 μg of the neurotoxin 6-hydroxydopamine (6-OHDA) was microinjected into left medial forebrain bundle. Crocin treatment and/or exercise continued for 6 more weeks. Spatial and aversive memories, rotational behaviour, inflammatory and oxidative stress parameters were assessed at the end of week 6 post surgery. The results showed that pretreatment with crocin alone and in combination with exercise decreased the total number of rotaions as compared with 6-OHDA-lesioned group. Furthermore, treatment of parkinsonian rats with crocin along with exercise training improved aversive and spatial memories. Biochemical analysis showed that crocin and exercise (alone and in combination) reduced tumor necrosis factor- (TNF) α levels in the striatum. Moreover, treatment with crocin at a dose of 100 mg/kg decreased the lipid peroxidation levels in the hippocampus, while exercise training increased the total thiol concentration. In conclusion, our findings indicated that pretreatment with crocin along with treadmill exercise ameliorated motor and memory deficits induced by 6-OHDA, which is considered to be due to their antioxidant and anti-inflammatory activities. The results suggest that combined therapy with crocin and exercise may be protective for motor and memory deficits in PD patients.

Dopamine, Oxidative Stress and Protein-Quinone Modifications in Parkinson's and Other Neurodegenerative Diseases

Dopamine (DA) is the most important catecholamine in the brain, as it is the most abundant and the precursor of other neurotransmitters. Degeneration of nigrostriatal neurons of substantia nigra pars compacta in Parkinson's disease represents the best-studied link between DA neurotransmission and neuropathology. Catecholamines are reactive molecules that are handled through complex control and transport systems. Under normal conditions, small amounts of cytosolic DA are converted to neuromelanin in a stepwise process involving melanization of peptides and proteins. However, excessive cytosolic or extraneuronal DA can give rise to nonselective protein modifications. These reactions involve DA oxidation to quinone species and depend on the presence of redox-active transition metal ions such as iron and copper. Other oxidized DA metabolites likely participate in post-translational protein modification. Thus, protein-quinone modification is a heterogeneous process involving multiple DA-derived residues that produce structural and conformational changes of proteins and can lead to aggregation and inactivation of the modified proteins.

miR-9-5p modulates the progression of Parkinson's disease by targeting SIRT1

Parkinson's disease (PD) is a most common progressive neurodegenerative disease mainly occurring in the elderly. Plenty of miRNAs are reported to involve in the progression of PD. However, the role of miR-9-5p in the regulation of PD pathogenesis remains unclear. The expressions of miR-9-5p and Sirtuin 1 (SIRT1) at mRNA and protein levels were determined by qRT-PCR and western blotting (WB) analyses. Cell viability and apoptosis were evaluated by MTT and flow cytometry. The levels of apoptosis-related proteins Bcl-2, Bax, Caspase-3 were detected by WB analysis. The releases of inflammatory cytokines IL-1β and TNF-α were examined by ELISA assay. ROS generation, LDH and SOD activity were evaluated using commercially available kits. Bioinformatics analysis, luciferase reporter, and qRT-PCR assays were performed to demonstrate the true interaction between miR-9-5p and SIRT1. Results showed miR-9-5p was upregulated and SIRT1 was downregulated in MPP⁺-treated SH-SY5Y cells in dose- and time- dependent manners. miR-9-5p knockdown attenuated MPP⁺-induced neurotoxicity in SH-SY5Y cells, as evidenced by the enhancement in cell viability, and the suppression in cell apoptosis, inflammation, and oxidative stress. SIRT1 was identified to be a target of miR-9-5p. Restoration of miR-9-5p aggravated SIRT1-attenuated neurotoxicity in MPP⁺-treated SH-SY5Y cells. Our data suggested these data indicated that miR-9-5p exerted a neurotoxic role in MPP⁺-derived PD by directly targeting STAT1, providing a potential therapeutic strategy for patients troubled by PD.

Mesenchymal Stem Cells-derived Exosomes: A New Possible Therapeutic Strategy for Parkinson's Disease?

Parkinson’s disease (PD) is the second most prevalent neurodegenerative disorder worldwide. Clinically, it is characterized by severe motor complications caused by a progressive degeneration of dopaminergic neurons (DAn) and dopamine loss. Current treatment is focused on mitigating the symptoms through administration of levodopa, rather than on preventing DAn damage. Therefore, the use and development of neuroprotective/disease-modifying strategies is an absolute need, which can lead to promising gains on PD translational research. Mesenchymal stem cells (MSCs)–derived exosomes have been proposed as a promising therapeutic tool, since it has been demonstrated that they can act as biological nanoparticles with beneficial effects in different pathological conditions, including PD. Thus, considering their potential protective action in lesioned sites, MSCs-derived exosomes might also be active modulators of the neuroregeneration processes, opening a door for their future use as therapeutical strategies in human clinical trials. Therefore, in this review, we analyze the current understanding of MSCs-derived exosomes as a new possible therapeutic strategy for PD, by providing an overview about the potential role of miRNAs in the cellular and molecular basis of PD.

Sophora Tomentosa Extract Prevents MPTP-Induced Parkinsonism in C57BL/6 Mice Via the Inhibition of GSK-3β Phosphorylation and Oxidative Stress

Sophora species are used as dietary medicines in aging-associated symptoms. Sophora tomentosa L. (ST) is a native medicinal plant in Southeast Asia; however, there is no pharmacological literature about ST extract. The present study evaluates the antioxidant phytoconstituent contents and radical scavenging capacities of ST extract. The further investigation was to clarify the neuroprotective mechanism of ST extract against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinsonism by assaying the activities of the dopaminergic system and antioxidant defenses, glycogen synthase kinase 3β (GSK3-β) phosphorylation, and α-synuclein levels in C57BL/6 mice. The results show that ST extract alleviated the motor deficits in MPTP-induced Parkinsonism with four behavioral tests, including a rearing locomotor, catalepsy test, balance beam walking test, and pole test. ST extract reversed the number of tyrosine hydroxylase (TH)-positive neurons in substantia nigra (SN) that had decreased by MPTP. ST extract also restored the decreased levels of dopamine and the expression of tyrosine hydroxylase (TH) in the striatum. Furthermore, ST extract restored the levels of glutathione (GSH) and the activities of antioxidant enzymes, and decreased the elevated levels of malondialdehyde (MDA) in mouse striatum. ST extract also decreased α-synuclein overexpression and GSK-3β phosphorylation in mouse striatum. In vitro, ST extract exerted higher 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging capacities through its higher phenolic contents, especially protocatechuic acid and epicatechin. These results suggest that ST extract has the potential to counteract MPTP-induced motor deficit. The neuroprotective mechanism of ST extract against MPTP-induced Parkinsonism might be related to decreasing GSK-3β phosphorylation and restoring the activities of striatal antioxidant defenses to restore the nigrostriatal dopaminergic function and decrease α-synuclein accumulation.