Disease-modifying strategies for Parkinson's disease

Association of Glycolysis-Enhancing α-1 Blockers With Risk of Developing Parkinson Disease

Question

Is use of glycolysis-enhancing drugs, such as terazosin, doxazosin, and alfuzosin, associated with decreased risk of Parkinson disease compared with use of tamsulosin, a drug prescribed for similar indications but which does not enhance glycolysis?

Findings

In this cohort study of 147 248 propensity score–matched pairs of terazosin/doxazosin/alfuzosin users and tamsulosin users from Danish nationwide health registries and the Truven Health Analytics MarketScan, the use of terazosin/doxazosin/alfuzosin was associated with a 12% to 37% decrease in Parkinson disease risk compared with use of tamsulosin.

Meaning

Use of terazosin/doxazosin/alfuzosin may lower the risk of developing Parkinson disease.

Importance

Parkinson disease (PD) is a common neurodegenerative disease. A treatment that prevents or delays development of PD is a critical unmet need. Terazosin and closely related drugs were recently discovered to enhance glycolysis and reduce PD progression in animal models and human clinical databases.

Objective

To determine whether use of terazosin, doxazosin, and alfuzosin is associated with a decreased risk of developing PD.

Design, Setting, and Participants

This cohort study used active comparator control and propensity score–matched data from Danish nationwide health registries, including the Danish National Prescription Registry, the Danish National Patient Registry, and the Danish Civil Registration System, from January 1996 to December 2017 and data from the Truven Health Analytics MarketScan database from January 2001 to December 2017. Men without PD who newly initiated terazosin/doxazosin/alfuzosin therapy or tamsulosin therapy, which is used for a similar indication (benign prostatic hyperplasia or unspecified urinary problems) but does not enhance glycolysis, and had at least 1 year of follow-up after medication start were included. In Denmark, the database included all residents, while the Truven database is a compilation of insurance claims across the US. Data were analyzed from February 2019 to July 2020.

Exposures

Patients who used terazosin/doxazosin/alfuzosin vs tamsulosin. Additional dose-response analyses were carried out.

Main Outcomes and Measures

Differences in the hazard of developing PD identified by diagnoses or use of PD-specific medications between patients who ever used terazosin/doxazosin/alfuzosin or tamsulosin.

Results

A cohort of 52 365 propensity score–matched pairs of terazosin/doxazosin/alfuzosin and tamsulosin users were identified in the Danish registries, of which all were male and the mean (SD) age was 67.9 (10.4) years, and 94 883 propensity score–matched pairs were identified in the Truven database, of which all were male and the mean (SD) age was 63.8 (11.1) years. Patients in the Danish cohort who used terazosin/doxazosin/alfuzosin had a hazard ratio (HR) for developing PD of 0.88 (95% CI, 0.81-0.98), and patients in the Truven cohort had an HR of 0.63 (95% CI, 0.58-0.69). There was a dose-response association with short-duration, medium-duration, and long-duration use of terazosin/doxazosin/alfuzosin users having a decreasing HR in both the Danish cohort (short: HR, 0.95; 95% CI, 0.84-1.07; medium: HR, 0.88; 95% CI, 0.77-1.01; long: HR, 0.79; 95% CI, 0.66-0.95) and Truven cohort (short: HR, 0.70; 95% CI, 0.64-0.76; medium: HR, 0.58; 95% CI, 0.52-0.64; long: HR, 0.46; 95% CI, 0.36-0.57).

Conclusions and Relevance

These data suggest that users of terazosin/doxazosin/alfuzosin are at lower hazard of developing PD compared with users of tamsulosin. Future work is needed to further assess this association.

Hip Fracture in Patients with Parkinson's Disease and Related Mortality: A Population-Based Study in Korea

INTRODUCTION

Patients with Parkinson's disease (PD) are prone to falls, thereby increasing the risk of fractures and mortality. This population-based study investigated the risk of hip fractures and their effect on mortality in patients with PD in Korea.

METHODS

National Health Insurance Service-National Sample Cohort data were used. Patients newly diagnosed with PD between 2006 and 2015 and age- and sex-matched individuals were classified into the PD group and the comparison group, respectively, with a 1:9 ratio. The Cox proportional hazards model was used to calculate hazard ratios (HRs), and the Kaplan-Meier method to identify survivorship.

RESULTS

In total, 26,570 individuals were enrolled in the study: 2,657 in the PD cohort and 23,913 in the matched comparison cohort. The PD group had about a 2 times higher risk of hip fracture than the comparison group (3.95 vs. 1.94%, p < 0.001). According to sex, the difference between the PD and comparison groups for the risk of hip fracture was greater in males than in females. The highest difference in HR for hip fracture between the PD and comparison groups was found in individuals aged between 60 and 69 years. Regarding post-fracture mortality in patients with PD, the mortality risk was twice as high in the patients with hip fracture than in those without. The effect of hip fracture on mortality between these 2 groups was also the highest in individuals aged between 60 and 69 years.

CONCLUSION

The PD group showed an approximately 2 times higher risk of hip fracture compared with the comparison group, and the post-fracture mortality rate was 2 times higher in the patients with PD with hip fracture than in those without. Those aged 60-69 years were associated with the highest risk of hip fracture and post-hip fracture mortality among patients with PD.

Suppressing Cdk5 Activity by Luteolin Inhibits MPP+-Induced Apoptotic of Neuroblastoma through Erk/Drp1 and Fak/Akt/GSK3β Pathways

Parkinson’s disease (PD) is characterized by the progressive degeneration of dopaminergic neurons. The cause of PD is still unclear. Oxidative stress and mitochondrial dysfunction have been linked to the development of PD. Luteolin, a non-toxic flavonoid, has become interested in an alternative medicine, according to its effects on anti-oxidative stress and anti-apoptosis, although the underlying mechanism of luteolin on PD has not been fully elucidated. This study aims to investigate whether luteolin prevents neurotoxicity induction by 1-methyl-4-phenylpyridinium iodide (MPP⁺), a neurotoxin in neuroblastoma SH-SY5Y cells. The results reveal that luteolin significantly improved cell viability and reduced apoptosis in MPP⁺-treated cells. Increasing lipid peroxidation and superoxide anion (O₂⁻), including mitochondrial membrane potential (Δψm) disruption, is ameliorated by luteolin treatment. In addition, luteolin attenuated MPP⁺-induced neurite damage via GAP43 and synapsin-1. Furthermore, Cdk5 is found to be overactivated and correlated with elevation of cleaved caspase-3 activity in MPP⁺-exposed cells, while phosphorylation of Erk1/2, Drp1, Fak, Akt and GSK3β are inhibited. In contrast, luteolin attenuated Cdk5 overactivation and supported phosphorylated level of Erk1/2, Drp1, Fak, Akt and GSK3β with reducing in cleaved caspase-3 activity. Results indicate that luteolin exerts neuroprotective effects via Cdk5-mediated Erk1/2/Drp1 and Fak/Akt/GSK3β pathways, possibly representing a potential preventive agent for neuronal disorder.

Modelling item scores of Unified Parkinson's Disease Rating Scale Part III for greater trial efficiency

AIMS

The multipart Unified Parkinson's Disease Rating Scale is the standard instrument in clinical trials. A sum of scores for all items in 1 or more parts of the instrument is usually analysed. Without accounting for relative importance of individual items, this sum of scores conceivably does not optimize the power of the instrument. The aim was to compare the ability to detect drug effect in slowing down motor function deterioration, as measured by Part III of the Scale-motor examinations-between the item scores and the sum of scores.

METHODS

We used data from 423 patients in a Parkinson's disease progression trial to estimate the symptom severity by item response modelling; modelled symptom progression using the severity and the sum of scores; and conducted simulations to compare the sensitivity of detecting a broad range of hypothetical drug effects on progression using the severity and the sum of scores.

RESULTS

The severity endpoint was far more sensitive than the sum of scores for detecting treatment effects, e.g. requiring 275 vs. 625 patients per arm to achieve 60% probability of trial success for detecting a range of potential effects in a 2-year trial. Nontremor items related to the left side of the body seemed most informative. The domain relevance of tremor items appeared questionable.

CONCLUSION

This analysis generated clear evidence that longitudinal modelling of item scores can enhance trial efficiency and success. It also called for reassessing the placement of the tremor items in the instrument.

Epidermal Fatty Acid-Binding Protein 5 (FABP5) Involvement in Alpha-Synuclein-Induced Mitochondrial Injury under Oxidative Stress

The accumulation of α-synuclein (αSyn) has been implicated as a causal factor in the pathogenesis of Parkinson’s disease (PD). There is growing evidence that supports mitochondrial dysfunction as a potential primary cause of dopaminergic neuronal death in PD. Here, we focused on reciprocal interactions between αSyn aggregation and mitochondrial injury induced by oxidative stress. We further investigated whether epidermal fatty acid-binding protein 5 (FABP5) is related to αSyn oligomerization/aggregation and subsequent disturbances in mitochondrial function in neuronal cells. In the presence of rotenone, a mitochondrial respiratory chain complex I inhibitor, co-overexpression of FABP5 with αSyn significantly decreased the viability of Neuro-2A cells compared to that of αSyn alone. Under these conditions, FABP5 co-localized with αSyn in the mitochondria, thereby reducing mitochondrial membrane potential. Furthermore, we confirmed that pharmacological inhibition of FABP5 by its ligand prevented αSyn accumulation in mitochondria, which led to cell death rescue. These results suggested that FABP5 is crucial for mitochondrial dysfunction related to αSyn oligomerization/aggregation in the mitochondria induced by oxidative stress in neurons.

Silencing of UCA1 Protects Against MPP+-Induced Cytotoxicity in SK-N-SH Cells via Modulating KCTD20 Expression by Sponging miR-423-5p

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder. Long noncoding RNA (lncRNA) urothelial carcinoma-associated 1 (UCA1) has been implicated in PD development. Nevertheless, little insight has been gained on the mechanisms of UCA1 in PD pathogenesis. The levels of UCA1, miR-423-5p and potassium channel tetramerization domain containing 20 (KCTD20) were assessed by qRT-PCR and western blot. Cell viability was gauged by the CCK-8 assay, and cell apoptosis was detected by flow cytometry. Targeted relationships among UCA1, miR-423-5p and KCTD20 were verified by dual-luciferase reporter and RNA immunoprecipitation assays. Our data showed that MPP⁺ induced UCA1 expression in SK-N-SH cells. UCA1 silencing protected against MPP⁺-evoked cytotoxicity in SK-N-SH cells. UCA1 functioned as a miR-423-5p sponge, and the protective impact of UCA1 silencing on MPP⁺-evoked cytotoxicity was mediated by miR-423-5p. KCTD20 was a direct target of miR-423-5p, and miR-423-5p overexpression mitigated MPP⁺-triggered cell injury by down-regulating KCTD20. Furthermore, UCA1 regulated KCTD20 expression by acting as a sponge of miR-423-5p in SK-N-SH cells. Our study first identified that the silencing of UCA1 protected SK-N-SH cells from MPP⁺-evoked cytotoxicity at least in part by targeting the miR-423-5p/KCTD20 axis.

Mirtazapine exerts astrocyte-mediated dopaminergic neuroprotection

Mirtazapine, a noradrenergic and specific serotonergic antidepressant (NaSSA), is known to activate serotonin (5-HT) 1A receptor. Our recent study demonstrated that stimulation of astrocytic 5-HT1A receptors promoted astrocyte proliferation and upregulated antioxidative property in astrocytes to protect dopaminergic neurons against oxidative stress. Here, we evaluated the neuroprotective effects of mirtazapine against dopaminergic neurodegeneration in models of Parkinson’s disease (PD). Mirtazapine administration attenuated the loss of dopaminergic neurons in the substantia nigra and increased the expression of the antioxidative molecule metallothionein (MT) in the striatal astrocytes of 6-hydroxydopamine (6-OHDA)-injected parkinsonian mice via 5-HT1A receptors. Mirtazapine protected dopaminergic neurons against 6-OHDA-induced neurotoxicity in mesencephalic neuron and striatal astrocyte cocultures, but not in enriched neuronal cultures. Mirtazapine-treated neuron-conditioned medium (Mir-NCM) induced astrocyte proliferation and upregulated MT expression via 5-HT1A receptors on astrocytes. Furthermore, treatment with medium from Mir-NCM-treated astrocytes protected dopaminergic neurons against 6-OHDA neurotoxicity, and these effects were attenuated by treatment with a MT-1/2-specific antibody or 5-HT1A antagonist. Our study suggests that mirtazapine could be an effective disease-modifying drug for PD and highlights that astrocytic 5-HT1A receptors may be a novel target for the treatment of PD.

Opicapone enhances the reversal of MPTP-induced Parkinson-like syndrome by levodopa in cynomolgus monkeys

Opicapone is a third generation nitrocatechol catechol-O-methyltransferase inhibitor that has received regional market approval for use as adjunctive therapy to levodopa in Parkinson's disease patients with motor fluctuations. This study evaluated the effects of opicapone as adjunct to levodopa in reversing a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced Parkinson's-like syndrome in cynomolgus monkeys in during opicapone preclinical development program. A Parkinson's-like syndrome was induced in cynomolgus monkeys by daily administrations of MPTP. Evaluation of the animals included scoring with the Primate Parkinsonism Motor Rating Scale (PPMRS) and assessment of locomotor activity. MPTP produced a stable Parkinson's-like behavioural syndrome as evidenced by tremor, postural changes, rigidity, impaired movements and balance, (PPMRS scores of 10-15) and decreased locomotor activity (13% of pre-MPTP values). Opicapone treatment alone, for 14 days, did not change Parkinson's-like symptoms nor decreased subject's locomotor behaviour. Ascending combinations of levodopa/benserazide dose-dependently decreased PPMRS and improved locomotor behaviour reaching statistical significance for levodopa/benserazide doses of 18/4.5 mg/kg and those effects were enhanced in opicapone treated subjects. Opicapone treated subjects as compared vehicle-treated, had markedly reduced erythrocyte catechol-O-methyltransferase activity, significantly increased plasma levodopa levels (1.8-fold higher AUC) with no statistically significant changes in C_max and significantly reduced 3-OMD AUC and C_max values (7.8- and 6.8-fold respectively). Opicapone potentiated the improvements in Parkinson's-like symptoms produced by levodopa/benserazide combinations with concomitant increase in plasma levodopa exposure, reduction of plasma 3-O-methyldopa levels and erythrocyte catechol-O-methyltransferase activity, results that were later demonstrated in 2 large Phase 3 studies in Parkinson's disease patients.

Ghrelin mitigates MPP+-induced cytotoxicity: Involvement of ERK1/2-mediated Nrf2/HO-1 and endoplasmic reticulum stress PERK signaling pathway

Parkinson's disease (PD) is a common progressive and multifactorial neurodegenerative disease. Current pharmacological therapies for PD are inadequate and often accompanied by serious side effects. In search of neuroprotective agents being considered to be beneficial to PD therapy. Ghrelin confers neuroprotective effect in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned PD model, but the underlying mechanism remains not fully elucidated. Here, we utilized human neuroblastoma SH-SY5Y cells exposed to MPP⁺ as a PD model to investigate the underlying mechanism of Ghrelin. In our present work, cell viability, cell apoptosis, oxidative stress-related indicators, and the level of Nrf2, HO-1, PERK, eIF2α, ATF4, CHOP, and ERK1/2 were examined. The results showed that Ghrelin attenuated MPP⁺-induced change of cell viability, apoptosis, coupled with decreased Cytochrome c, caspase-9, and caspase-3 expressions. Consistently, Ghrelin suppressed MPP⁺-induced oxidative stress. Moreover, Ghrelin markedly enhanced Nrf2 expression and nuclear accumulation as well as HO-1 induction. Further investigations showed that Ghrelin significantly inhibited the endoplasmic reticulum stress PERK-eIF2α-ATF4-CHOP pathway. Interestingly, we then found that Ghrelin promoted phosphorylation of ERK1/2, and pharmacological inhibition of ERK signaling abolished the cytoprotective effect of Ghrelin. Furthermore, we also found promoting the activation of the Nrf2/ HO-1 pathway and suppressing of the PERK pathway were mediated by ERK1/2. These findings provided novel insights into the underlying mechanisms of Ghrelin exerted protective effect, suggesting its potential as a novel therapeutic strategy against PD.

A New Approach to the Development of Disease-Modifying Therapies for PD; Fighting Another Pandemic

A disease‐modifying therapy that slows disease progression and development of disability is the major unmet need in the treatment of Parkinson's disease. Recent scientific advances suggest many promising and exciting new interventions. However, despite these opportunities, the cost, time and uncertainty of being able to receive an indication as a disease‐modifying therapy has caused many pharmaceutical companies to abandon development of potentially disease‐modifying drugs. We propose a new approach to development of these agents that will reduce the cost and facilitate approval of putative disease‐modifying drugs that should prove acceptable to pharmaceutical companies and regulatory agencies. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Nanostructured Lipid Carriers Made of Ω-3 Polyunsaturated Fatty Acids: In Vitro Evaluation of Emerging Nanocarriers to Treat Neurodegenerative Diseases

Neurodegenerative diseases (ND) are one of the main problems of public health systems in the 21st century. The rise of nanotechnology-based drug delivery systems (DDS) has become in an emerging approach to target and treat these disorders related to the central nervous system (CNS). Among others, the use of nanostructured lipid carriers (NLCs) has increased in the last few years. Up to today, most of the developed NLCs have been made of a mixture of solid and liquid lipids without any active role in preventing or treating diseases. In this study, we successfully developed NLCs made of a functional lipid, such as the hydroxylated derivate of docohexaenoic acid (DHAH), named DHAH-NLCs. The newly developed nanocarriers were around 100 nm in size, with a polydispersity index (PDI) value of <0.3, and they exhibited positive zeta potential due to the successful chitosan (CS) and TAT coating. DHAH-NLCs were shown to be safe in both dopaminergic and microglia primary cell cultures. Moreover, they exhibited neuroprotective effects in dopaminergic neuron cell cultures after exposition to 6-hydroxydopamine hydrochloride (6-OHDA) neurotoxin and decreased the proinflammatory cytokine levels in microglia primary cell cultures after lipopolysaccharide (LPS) stimuli. The levels of the three tested cytokines, IL-6, IL-1β and TNF-α were decreased almost to control levels after the treatment with DHAH-NLCs. Taken together, these data suggest the suitability of DHAH-NLCs to attaining enhanced and synergistic effects for the treatment of NDs.

Anti-inflammatory and Neuroprotective Agents in Clinical Trials for CNS Disease and Injury: Where Do We Go From Here?

Neurological disorders are major contributors to death and disability worldwide. The pathology of injuries and disease processes includes a cascade of events that often involve molecular and cellular components of the immune system and their interaction with cells and structures within the central nervous system. Because of this, there has been great interest in developing neuroprotective therapeutic approaches that target neuroinflammatory pathways. Several neuroprotective anti-inflammatory agents have been investigated in clinical trials for a variety of neurological diseases and injuries, but to date the results from the great majority of these trials has been disappointing. There nevertheless remains great interest in the development of neuroprotective strategies in this arena. With this in mind, the complement system is being increasingly discussed as an attractive therapeutic target for treating brain injury and neurodegenerative conditions, due to emerging data supporting a pivotal role for complement in promoting multiple downstream activities that promote neuroinflammation and degeneration. As we move forward in testing additional neuroprotective and immune-modulating agents, we believe it will be useful to review past trials and discuss potential factors that may have contributed to failure, which will assist with future agent selection and trial design, including for complement inhibitors. In this context, we also discuss inhibition of the complement system as a potential neuroprotective strategy for neuropathologies of the central nervous system.

Building a Parkinson-Network-Experiences from Germany

Parkinson’s disease is a complex neurodegenerative disease that can be best treated with a multi-disciplinary care approach. Building care networks has been shown as a useful tool to facilitate the integration of care services and improve outcomes for patients and care providers. However, experiences and practices relating to building a network are very limited in the field of Parkinson’s disease. This paper portrays existing Parkinson networks in Germany. With the help of a standardized template, description of networks and their building-blocks, so-called modules, were collected from all over Germany. Modules were rated in terms of their expected benefit and the required effort when implementing them, with the help of an expert survey. The rating showed that some modules were perceived as more important than others, but all modules were recognized as beneficial for patients and care providers. Overall, the German experience shows that building a Parkinson network facilitates the integration of care and provides a benefit to all stakeholders involved.

Human Adipose Tissue-Derived Mesenchymal Stem Cells in Parkinson's Disease: Inhibition of T Helper 17 Cell Differentiation and Regulation of Immune Balance Towards a Regulatory T Cell Phenotype

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative disorder displaying a typical neuroinflammation pathology that may result from an imbalance between regulatory T cells (Treg) and T helper 17 (Th17) cells. Human adipose tissue-derived mesenchymal stem cells (Ad-MSCs) exert immunomodulatory effects by inhibiting effector T cell responses and have been used to treat diverse immune disorders. We aimed to investigate the modulating effect of human Ad-MSCs on peripheral blood mononuclear cells (PBMCs) of patients with PD, focusing on differentiation into Th17 and Treg cells.

METHODS

We isolated human peripheral blood CD4+T cells and co-cultured them with Ad-MSCs at a ratio of 4:1 under either Th17 or Treg cell polarizing conditions for 4 days to detect the proportions of IL-17-producing CD4+T (Th17) and CD4+CD25+Foxp3+regulatory T (Treg) cells by flow cytometry. We also determined the mRNA expression levels of the retinoid-related orphan nuclear receptor (RORγt) transcription factor and those of interleukin-6 receptor (IL-6R), interleukin-23 receptor (IL-23R), leukemia inhibitory factor (LIF), and LIF receptor (LIFR) by quantitative reverse transcription PCR. We detected levels of cytokines in the supernatant (including LIF, IL-6, IL-23, IL-10, and TGF-β) using ELISA.

RESULTS

Our results showed that Ad-MSCs specifically inhibited the differentiation of PBMCs of patients with PD into IL-17-producing CD4+T cells by decreasing expressions of IL-6R, IL-23R, and RORγt (the key transcription factor for Th17 cells). Moreover, Ad-MSCs induced a functional CD4+CD25+Foxp3+T regulatory cell phenotype as evidenced by the secretion of IL-10. The levels of IL-6, IL-23, and TGF-β remained constant after co-culture under either the Th17 or the Treg cell polarizing condition. In addition, levels of LIF protein and its receptor mRNA were significantly increased under both polarizing conditions.

CONCLUSION

The present in vitro study found that Ad-MSCs from healthy participants were able to correct the imbalance between Th17 and Treg found in PBMCs of PD patients, which were correlated with an increase in LIF secretion and a decrease in expression of IL-6R, IL-23R, and RORγt. These findings should be confirmed by in vivo experiments.

Parkinson's Disease-Related Motor and Nonmotor Symptoms in the Lancaster Amish

INTRODUCTION

Previous research has suggested that the Amish may experience a relatively high prevalence of Parkinson's disease (PD) and/or parkinsonian motor signs.

METHODS

In a large sample from the Amish community in Lancaster County, Pennsylvania, age ≥18 years, we assessed the prevalence of self-reported PD diagnosis. For those without self-reported PD diagnosis, we assessed the frequency of PD-related motor symptoms using a 9-item questionnaire that was designed by the PD Epidemiology Research Group. Lastly, we queried study participants for the presence of 2 nonmotor symptoms that have been commonly linked to PD: bowel movement frequency and daytime sleepiness.

RESULTS

Among 2,025 subjects who answered the PD questionnaire, 430 were older than 60 years. Of 430 participants ≥60 years, 5 (1.2%) reported a PD diagnosis. Of those without a PD diagnosis, 10.5% reported ≥1 and 1.2% ≥ 4 motor symptoms for the 9-item PD screening questionnaire. Of the 3,789 subjects who answered the question about bowel movement frequency, 0.7% reported ≤3 bowel movements per week. Among 1,710 subjects who answered the question about daytime sleepiness, 8.1% of the participants reported "always" sleepy during the day.

DISCUSSION

These data neither support a markedly higher PD prevalence in the older Lancaster Amish nor do they show dramatically higher motor and/or selected nonmotor symptoms than the general population. Future studies that employ more rigorous procedures for case identification and PD-specific preclinical symptoms/tests are needed to determine the potential differences and similarities among different Amish populations and between Amish and non-Amish populations.

Ghrelin protects dopaminergic neurons against MPTP neurotoxicity through promoting autophagy and inhibiting endoplasmic reticulum mediated apoptosis

Parkinson's disease (PD) is the second most common progressive neurodegenerative disorder, the important pathology of PD due to the prominent loss of the dopaminergic neurodegeneration in the substantia nigra pars compacta (SNpc) and striatum (STR). Although the etiology of PD is not fully understood, aggregation of α-synuclein, impaired autophagy, and endoplasmic reticulum stress (ERS) are involved in the pathogenesis of PD. Previously it has been demonstrated that Ghrelin is a kind of peptide protected dopaminergic neurons against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyran (MPTP)-induced neurotoxicity, but the detailed mechanism remains to be elucidated. In the present work, we investigated the effects of Ghrelin on autophagy and ERS-mediated apoptosis in the MPTP-lesioned PD mice model. We found that Ghrelin was neuroprotective against MPTP-induced dopaminergic neurodegeneration. Subsequently, we investigated Ghrelin inhibited the accumulation and phosphorylation of α-synuclein induced by MPTP. Moreover, Ghrelin promoted autophagy indicated by the up-regulation of microtubule-associated protein 1 Light Chain 3B-II/I (LC3B-II/I) and Beclin1, as well as decreasing the level of p62 in the SNpc and STR. Besides, the activation of the ERS-related apoptosis signaling pathway including IRE1α and Caspase-12 signaling pathway induced by MPTP was suppressed by Ghrelin treatment. Furthermore, Ghrelin also decreased Caspase-3 expression. Taken together, our results indicated that Ghrelin may exert neuroprotective effects via regulating α-synuclein activities, enhancing autophagy, and ameliorating ERS-mediated apoptosis in MPTP-lesioned mice, which provides a new target for potential pharmacologic interventions of PD treatment in the future.

Dopamine D3 Receptor Heteromerization: Implications for Neuroplasticity and Neuroprotection

The dopamine (DA) D3 receptor (D3R) plays a pivotal role in the control of several functions, including motor activity, rewarding and motivating behavior and several aspects of cognitive functions. Recently, it has been reported that the D3R is also involved in the regulation of neuronal development, in promoting structural plasticity and in triggering key intracellular events with neuroprotective potential. A new role for D3R-dependent neurotransmission has thus been proposed both in preserving DA neuron homeostasis in physiological conditions and in preventing pathological alterations that may lead to neurodegeneration. Interestingly, there is evidence that nicotinic acetylcholine receptors (nAChR) located on DA neurons also provide neurotrophic support to DA neurons, an effect requiring functional D3R and suggesting the existence of a positive cross-talk between these receptor systems. Increasing evidence suggests that, as with the majority of G protein-coupled receptors (GPCR), the D3R directly interacts with other receptors to form new receptor heteromers with unique functional and pharmacological properties. Among them, we recently identified a receptor heteromer containing the nAChR and the D3R as the molecular effector of nicotine-mediated neurotrophic effects. This review summarizes the functional and pharmacological characteristics of D3R, including the capability to form active heteromers as pharmacological targets for specific neurodegenerative disorders. In particular, the molecular and functional features of the D3R-nAChR heteromer will be especially discussed since it may represent a possible key etiologic effector for DA-related pathologies, such as Parkinson’s disease (PD), and a target for drug design.

Neuroprotective potential of Ayahuasca and untargeted metabolomics analyses: applicability to Parkinson's disease

ETHNOPHARMACOLOGY RELEVANCE

Ayahuasca is a tea produced through decoction of Amazonian plants. It has been used for centuries by indigenous people of South America. The beverage is considered to be an ethnomedicine, and it is traditionally used for the treatment of a wide range of diseases, including neurological illness. Besides, some scientific evidence suggests it may be applicable to Parkinson's disease (PD) treatment. Thus, Ayahuasca deserves in depth studies to clarify its potential role in this disease.

AIM OF THE STUDY

This study aimed to use an untargeted metabolomics approach to evaluate the neuroprotective potential of the Ayahuasca beverage, the extracts from its matrix plants (Banisteriopsis caapi and Psychotria viridis), its fractions and its main alkaloids on the viability of SH-SY5Y neuroblastoma cells in an in vitro PD model.

MATERIAL AND METHODS

The cytotoxicity of Ayahuasca, crude extracts, and fractions of B. caapi and P. viridis, as well as neuroprotection promoted by these samples in a 6-hydroxydopamine (6-OHDA)-induced neurodegeneration model, were evaluated by the MTT assay at two time-points: 48 h (T1) and 72 h (T2). The main alkaloids from Ayahuasca matrix plants, harmine (HRE) and N,N-dimethyltryptamine (DMT), were also isolated and evaluated. An untargeted metabolomics approach was developed to explore the chemical composition of samples with neuroprotective activity. Ultra-Performance Liquid Chromatography coupled to Electrospray Ionisation and Time-of-Flight (UPLC-ESI-TOF) metabolome data was treated and further analysed using multivariate statistical analyses (MSA): principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). The metabolites were dereplicated using the Dictionary of Natural Products and an in house database. The main alkaloids were also quantified by UPLC-MS/MS.

RESULTS

The samples did not cause cytotoxicity in vitro and three of samples intensely increased cell viability at T1. The crude extracts, alkaloid fractions and HRE demonstrated remarkable neuroprotective effect at T2 while the hydroalcoholic fractions demonstrated this neuroprotective effect at T1 and T2. Several compounds from different classes, such as β-carbolines and monoterpene indole alkaloids (MIAs) were revealed correlated with this property by MSA. Additionally, a total of 2419 compounds were detected in both ionisation modes. HRE showed potent neuroprotective action at 72 h, but it was not among the metabolites positively correlated with the most efficacious neuroprotective profile at either time (T1 and T2). Furthermore, DMT was statistically important to differentiate the dataset (VIP value > 1), although it did not exhibit sufficient neuroprotective activity by in vitro assay, neither a positive correlation with T1 and T2 neuroprotective profile, which corroborated the MSA results.

CONCLUSION

The lower doses of the active samples stimulated neuronal cell proliferation and/or displayed the most efficacious neuroprotection profile, namely by preventing neuronal damage and improving cell viability against 6-OHDA-induced toxicity. Intriguingly, the hydroalcoholic fractions exhibited enhanced neuroprotective effects when compared to other samples and isolated alkaloids. This finding corroborates the significance of a holistic approach. The results demonstrate that Ayahuasca and its base plants have potential applicability for PD treatment and to prevent its progression differently from current drugs to treat PD.

Metformin as a Potential Neuroprotective Agent in Prodromal Parkinson's Disease-Viewpoint

To date, there are no clinically effective neuroprotective or disease-modifying treatments that can halt Parkinson's disease (PD) progression. The current clinical approach focuses on symptomatic management. This failure may relate to the complex neurobiology underpinning the development of PD and the absence of true translational animal models. In addition, clinical diagnosis of PD relies on presentation of motor symptoms which occur when the neuropathology is already established. These multiple factors could contribute to the unsuccessful development of neuroprotective treatments for PD. Prodromal symptoms develop years prior to formal diagnosis and may provide an excellent tool for early diagnosis and better trial design. Patients with idiopathic rapid eye movement behavior disorder (iRBD) have the highest risk of developing PD and could represent an excellent group to include in neuroprotective trials for PD. In addition, repurposing drugs with excellent safety profiles is an appealing strategy to accelerate drug discovery. The anti-diabetic drug metformin has been shown to target diverse cellular pathways implicated in PD progression. Multiple studies have, additionally, observed the benefits of metformin to counteract other age-related diseases. The purpose of this viewpoint is to discuss metformin's neuroprotective potential by outlining relevant mechanisms of action and the selection of iRBD patients for future clinical trials in PD.

Experiential Neurorehabilitation: A Neurological Therapy Based on the Enactive Paradigm

With the arrival of the cognitive paradigm during the latter half of the last century, the theoretical and scientific bases of neurorehabilitation have been linked to the knowledge developed in cognitive neuropsychology and cognitive neuroscience. Although the knowledge generated by these disciplines has made relevant contributions to neurological therapy, their theoretical premises may create limitations in therapeutic processes. The present manuscript has two main objectives: first, to explicitly set forth the theoretical bases of cognitive neurorehabilitation and critically analyze the repercussions that these premises have produced in clinical practice; and second, to propose the enactive paradigm to reinterpret perspectives on people with brain damage and their therapy (assessment and treatment). This analysis will show that (1) neurorehabilitation as a therapy underutilizes body-originated resources that aid in recovery from neurological sequelae (embrained therapy); (2) the therapeutic process is based exclusively on subpersonal explanation models (subpersonal therapy); and (3), neurorehabilitation does not take subjectivity of each person in their own recovery processes into account (anti-subjective therapy). Subsequently, and in order to attenuate or resolve the conception of embrained, subpersonal and anti-subjective therapy, I argue in support of incorporating the enactive paradigm in rehabilitation of neurological damage. It is proposed here under a new term, "experiential neurorehabilitation." This proposal approaches neurological disease and its sequelae as alterations in dynamic interaction between the body structure and the environment in which the meaning of the experience is also altered. Therefore, when a person is not able to walk, remember the past, communicate a thought, or maintain efficient self-care, their impairments are not only a product of an alteration in a specific cerebral area or within information processing; rather, the sequelae of their condition stem from alterations in the whole living system and its dynamics with the environment. The objective of experiential neurorehabilitation is the recovery of the singular and concrete experience of the person, composed of physical and subjective life attributes.

Orally Administered Nanotherapeutics For Parkinson's Disease: An Old Delivery System Yet More Acceptable

As per the present global scenario, Parkinson's disease (PD) is considered to be the second most common neurodegenerative disorder which is a keen area of interest among researchers. The conventional therapies generally employed against PD are associated with serious drawbacks including limited transport across selectively permeable BBB, hepatic metabolism, intestinal barrier, etc. This urges the need to develop novel therapeutic alternatives. The oral route being the most preferred route of administration needs to be explored for new and more intelligent drug delivery systems. Nanotechnology has been proposed to play a promising role in reversing the progression of the disease via the oral route. Nanocarriers, namely nanoparticles, lipid nanoparticles, nanoemulsions, nanocrystals, nanomicellar formulations, self-nanoemulsifying drug delivery systems and alginate nanocomposites have been investigated upon to modulate the fate of drugs inside the human body when administered orally. The development of various nanotherapeutics for the treatment of PD has been reviewed, depicting an enhanced bioavailability to provide a desired therapeutic outcome. The new advances in the therapy have been explored and highlighted through the body of this review. However, a therapeutically effective concentration at the target site remains a challenge, therefore extensive exploration in the field of nanotherapeutics may facilitate superior drug delivery to CNS via oral route thereby improving the state of disease progression.

MicroRNA-150 serves as a diagnostic biomarker and is involved in the inflammatory pathogenesis of Parkinson's disease

Background

Dysregulation of microRNAs (miRNAs) has been reported to be involved in the neuroinflammatory pathogenesis of PD. This study aimed to investigate the serum expression of microRNA‐150 (miR‐150) in Parkinson's disease (PD) patients and further uncover the regulatory effect of miR‐150 on neuroinflammation.

Methods

Quantitative Real‐Time PCR was used to measure the expression of miR‐150. A receiver operating characteristic curve was applied to evaluate the diagnostic value of miR‐150. The effect of miR‐150 on neuroinflammation was analyzed by examining its correlation with proinflammatory cytokines and gain‐of‐function experiments in microglia treated with LPS.

Results

Serum miR‐150 expression was downregulated in PD patients compared with the healthy controls, and served as a candidate diagnostic biomarker for the screening of PD cases. Negative correlation was found between miR‐150 levels and the levels of procytokines in PD patients. By the treatment of LPS, microglia BV2 cells had a reduced expression of miR‐150, and the enhanced neuroinflammatory responses were inhibited by the overexpression of miR‐150. AKT3 was verified as a target of miR‐150 in BV2 cells.

Conclusion

All the data of this study revealed that the decreased serum miR‐150 serves as a potential diagnostic biomarker. The methods to increase miR‐150 expression may have a beneficial effect in PD via suppressing the neuroinflammation by targeting AKT3.

Leucine-rich repeat kinase 2 inhibitors: a patent review (2014-present)

Introduction: Disease-modifying treatment for Parkinson's disease (PD) to halt or revert the disease progression remains an unmet medical need. LRRK2 kinase activity is abnormally elevated in PD patients carrying LRRK2 mutations, with G2019S as the most frequent one. Small molecules to inhibit LRRK2 kinase activity might provide a potential disease-modifying strategy for PD.Areas covered: This review provides an update of small molecule LRRK2 inhibitors in patents published from January 2014 to October 2019. The molecules are classified by their structural scaffolds.Expert opinion: Despite the tremendous efforts to push small molecule LRRK2 inhibitors toward clinical trials, the overall progress is somewhat disappointing due to the challenges in compound optimization and the putative concern of target-related adverse effects. It is challenging to optimize multiple parameters including kinase selectivity, CNS penetration, and unbound fraction in brain simultaneously. In addition, the on-target effect of morphologic changes observed in lung/kidney in pre-clinical studies for several frontrunner ATP-competitive inhibitors prevented their further development. With this regard, non-ATP-competitive inhibitors may provide a different safety profile for development. DNL201 and DNL151 have entered early clinical trials to evaluate tolerability and target engagement biomarkers. This will pave the way for the development for future LRRK2 inhibitors.

Parkinson Disease Epidemiology, Pathology, Genetics, and Pathophysiology

Parkinson disease is a complex, age-related, neurodegenerative disease associated with dopamine deficiency and both motor and nonmotor deficits. Many environmental and genetic factors influence Parkinson disease risk, with different factors predominating in different patients. These factors converge on specific pathways, including mitochondrial dysfunction, oxidative stress, protein aggregation, impaired autophagy, and neuroinflammation. Ultimately, treatment of Parkinson disease may focus on targeted therapies for pathophysiologically defined subtypes of Parkinson disease patients.

Deep Phenotyping of Parkinson's Disease

Phenotype is the set of observable traits of an organism or condition. While advances in genetics, imaging, and molecular biology have improved our understanding of the underlying biology of Parkinson's disease (PD), clinical phenotyping of PD still relies primarily on history and physical examination. These subjective, episodic, categorical assessments are valuable for diagnosis and care but have left gaps in our understanding of the PD phenotype. Sensors can provide objective, continuous, real-world data about the PD clinical phenotype, increase our knowledge of its pathology, enhance evaluation of therapies, and ultimately, improve patient care. In this paper, we explore the concept of deep phenotyping-the comprehensive assessment of a condition using multiple clinical, biological, genetic, imaging, and sensor-based tools-for PD. We discuss the rationale for, outline current approaches to, identify benefits and limitations of, and consider future directions for deep clinical phenotyping.

Anti-neuroinflammatory, protective effects of the synthetic microneurotrophin BNN-20 in the advanced dopaminergic neurodegeneration of "weaver" mice

BNN-20 is a synthetic microneurotrophin, long-term (P1-P21) administration of which exerts potent neuroprotective effect on the "weaver" mouse, a genetic model of progressive, nigrostriatal dopaminergic degeneration. The present study complements and expands our previous work, providing evidence that BNN-20 fully protects the dopaminergic neurons even when administration begins at a late stage of dopaminergic degeneration (>40%). Since neuroinflammation plays a critical role in Parkinson's disease, we investigated the possible anti-neuroinflammatory mechanisms underlying the pharmacological action of BNN-20. The latter was shown to be microglia-mediated, at least in part. Indeed, BNN-20 induced a partial, but significant, reversal of microglia hyperactivation, observed in the untreated "weaver" mouse. Furthermore, it induced a shift in microglia polarization towards the neuroprotective M2 phenotype, suggesting a possible beneficial shifting of microglia activity. This observation was further supported by morphometric measurements. Moreover, BDNF levels, which were severely reduced in the "weaver" mouse midbrain, were restored to normal even after short-term BNN-20 administration. Experiments in "weaver"/NGL (dual GFP/luciferase-NF-κВ reporter) mice using bioluminescence after a short BNN-20 treatment (P60-P74), have shown that the increase of BDNF production was specifically mediated through the TrkB-PI3K-Akt-NF-κB signaling pathway. Interestingly, long-term BNN-20 treatment (P14-P60) significantly increased dopamine levels in the "weaver" striatum, which seems to be associated with the improved motor activity observed in the treated mutant animals. In conclusion, our findings suggest that BNN-20 may serve as a lead molecule for new therapeutic compounds for Parkinson's disease, combining strong anti-neuroinflammatory and neuroprotective properties, leading to elevated dopamine levels and improved motor activity.

Neuroprotection in Parkinson's disease: facts and hopes

Parkinson’s disease (PD) is the second most common neurodegenerative disease worldwide. Behind the symptoms there is a complex pathological mechanism which leads to a dopaminergic cell loss in the substantia nigra pars compacta. Despite the strong efforts, curative treatment has not been found yet. To prevent a further cell death, numerous molecules were tested in terms of neuroprotection in preclinical (in vitro, in vivo) and in clinical studies as well. The aim of this review article is to summarize our knowledge about the extensively tested neuroprotective agents (Search period: 1991–2019). We detail the underlying pathological mechanism and summarize the most important results of the completed animal and clinical trials. Although many positive results have been reported in the literature, there is still no evidence that any of them should be used in clinical practice (Cochrane analysis was performed). Therefore, further studies are needed to better understand the pathomechanism of PD and to find the optimal neuroprotective agent(s).

Marine omega-3 (n-3) phospholipids: A comprehensive review of their properties, sources, bioavailability, and relation to brain health

For several decades, there has been considerable interest in marine-derived long chain n-3 fatty acids (n-3 LCPUFAs) due to their outstanding health benefits. n-3 LCPUFAs can be found in nature either in triglycerides (TAGs) or in phospholipid (PL) form. From brain health point of view, PL n-3 is more bioavailable and potent compared to n-3 in TAG form, as only PL n-3 is able to cross the blood-brain barrier and can be involved in brain biochemical reactions. However, PL n-3 has been ignored in the fish oil industry and frequently removed as an impurity during degumming processes. As a result, PL products derived from marine sources are very limited compared to TAG products. Commercially, PLs are being used in pharmaceutical industries as drug carriers, in food manufacturing as emulsifiers and in cosmetic industries as skin care agents, but most of the PLs used in these applications are produced from vegetable sources that contain less (without EPA, DPA, and DHA) or sometimes no n-3 LCPUFAs. This review provides a comprehensive account of the properties, structures, and major sources of marine PLs, and provides focussed discussion of their relationship to brain health. Epidemiological, laboratory, and clinical studies on n-3 LCPUFAs enriched PLs using different model systems in relation to brain and mental health that have been published over the past few years are discussed in detail.

The evolution of geriatric neurology

The founders of neurology in the late 19th century and early 20th century laid the foundation for modern geriatric neurology by detailed observations, in their patients, of the clinical expressions of aging of the nervous system. Further advances in clinical manifestations of aging and more detailed examination of disease states in the elderly accelerated in the last quarter of the 20th century. Basic, translational, and clinical research support of geriatric neurology studies expanded and advanced during this period and into the 21st century. The size and sophistication of this movement was stimulated by a number of factors: the successful development of geriatrics as a specialty in primary care, internal medicine, and psychiatry; the projected growth of the geriatric population; and the projections of the number of people with Alzheimer's disease. However, there were and continue to be inadequate numbers of trained geriatric neurologists available to care for the "silver tsunami" of elderly patients with age-related diseases that will present in the next 3 decades. The combination of massive investment in dementia/Alzheimer's research in the past decade, widespread awareness among researchers and trainees of the opportunities to do research in age-related diseases, and the need for further knowledge of neurodegenerative diseases led to a broad expansion of research efforts. Longitudinal clinical studies of the elderly and the advent of sophisticated neuroimaging, genetics, and laboratory techniques are advancing the field. The initiation of therapeutic interventions has led to cautious optimism about the ability to ameliorate suffering in these patients and diminish the burdens of central nervous system aging.

Peripheral Immunity, Immunoaging and Neuroinflammation in Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder among elderly population, characterized by the progressive degeneration of dopaminergic neurons in the midbrain. To date, exact cause remains unknown and the mechanism of neurons death uncertain. It is typically considered as a disease of central nervous system (CNS). Nevertheless, numerous evidence has been accumulated in several past years testifying undoubtedly about the principal role of neuroinflammation in progression of PD. Neuroinflammation is mainly associated with presence of activated microglia in brain and elevated levels of cytokine levels in CNS. Nevertheless, active participation of immune system as well has been noted, such as, elevated levels of cytokine levels in blood, the presence of auto antibodies, and the infiltration of T cell in CNS. Moreover, infiltration and reactivation of those T cells could exacerbate neuroinflammation to greater neurotoxic levels. Hence, peripheral inflammation is able to prime microglia into pro-inflammatory phenotype, which can trigger stronger response in CNS further perpetuating the on-going neurodegenerative process. In the present review, the interplay between neuroinflammation and the peripheral immune response in the pathobiology of PD will be discussed. First of all, an overview of regulation of microglial activation and neuroinflammation is summarized and discussed. Afterwards, we try to collectively analyze changes that occurs in peripheral immune system of PD patients, suggesting that these peripheral immune challenges can exacerbate the process of neuroinflammation and hence the symptoms of the disease. In the end, we summarize some of proposed immunotherapies for treatment of PD.

A mitochondrial uncoupler prodrug protects dopaminergic neurons and improves functional outcome in a mouse model of Parkinson's disease

Dopaminergic neuronal cell loss in the substantia nigra is responsible for the motor symptoms that are the clinical hallmark of Parkinson's disease (PD). As of yet there are no treatments that slow or prevent the degeneration of dopaminergic neurons in PD patients. Here we tested the hypothesis that dopaminergic neurons can be protected by treatment with the mitochondrial uncoupling agent 2,4-dinitrophenol (DNP) and the novel DNP prodrug MP201. We found that mice treated with low doses of DNP and MP201 were protected against motor dysfunction and dopamine neuron loss in the 6-hydroxydopamine PD model, with MP201 being more efficacious than DNP. Amelioration of motor deficits and dopamine neuron loss by MP201 treatment was associated with reductions in microglial and astrocyte activation and neuroinflammation. These preclinical findings suggest the potential application of mitochondrial uncoupling agents such as MP201 as disease-modifying therapies for PD.

"Buckets": Early Observations on the Use of Red and Infrared Light Helmets in Parkinson's Disease Patients

Background: Parkinson's disease is a well-known neurological disorder with distinct motor signs and non-motor symptoms. Objective: We report on six patients with Parkinson's disease that used in-house built photobiomodulation (PBM) helmets. Methods: We used "buckets" lined with light-emitting diodes (LEDs) of wavelengths across the red to near-infrared range (i.e., 670, 810, and 850 nm; n = 5) or an homemade intranasal LED device (660 nm; n = 1). Progress was assessed by the patients themselves, their spouse, or their attending medical practitioners. Results: We found that 55% of the initial signs and symptoms of the six patients showed overall improvement, whereas 43% stayed the same and only 2% got worse. We also found that PBM did not target a specific sign or symptom, with both motor and nonmotor ones being affected, depending on the patient. Conclusions: In summary, our early observations are the first to note the impact of PBM on patients' signs and symptoms over an extended period, up to 24 months, and lays the groundwork for further development to clinical trial.

To be or not to be pink(1): contradictory findings in an animal model for Parkinson's disease

The PTEN-induced putative kinase 1 knockout rat (Pink1^-/-) is marketed as an established model for Parkinson's disease, characterized by development of motor deficits and progressive degeneration of half the dopaminergic neurons in the substantia nigra pars compacta by 8 months of age. In this study, we address our concerns about the reproducibility of the Pink1^-/- rat model. We evaluated behavioural function, number of substantia nigra dopaminergic neurons and extracellular striatal dopamine concentrations by in vivo microdialysis. Strikingly, we and others failed to observe any loss of dopaminergic neurons in 8-month-old male Pink1^-/- rats. To understand this variability, we compared key experimental parameters from the different studies and provide explanations for contradictory findings. Although Pink1^-/- rats developed behavioural deficits, these could not be attributed to nigrostriatal degeneration as there was no loss of dopaminergic neurons in the substantia nigra and no changes in neurotransmitter levels in the striatum. To maximize the benefit of Parkinson's disease research and limit the unnecessary use of laboratory animals, it is essential that the research community is aware of the limits of this animal model. Additional research is needed to identify reasons for inconsistency between Pink1^-/- rat colonies and why degeneration in the substantia nigra is not consistent.

The Personalized Parkinson Project: examining disease progression through broad biomarkers in early Parkinson's disease

BACKGROUND

Our understanding of the etiology, pathophysiology, phenotypic diversity, and progression of Parkinson's disease has stagnated. Consequently, patients do not receive the best care, leading to unnecessary disability, and to mounting costs for society. The Personalized Parkinson Project (PPP) proposes an unbiased approach to biomarker development with multiple biomarkers measured longitudinally. Our main aims are: (a) to perform a set of hypothesis-driven analyses on the comprehensive dataset, correlating established and novel biomarkers to the rate of disease progression and to treatment response; and (b) to create a widely accessible dataset for discovery of novel biomarkers and new targets for therapeutic interventions in Parkinson's disease.

METHODS/DESIGN

This is a prospective, longitudinal, single-center cohort study. The cohort will comprise 650 persons with Parkinson's disease. The inclusion criteria are purposely broad: age ≥ 18 years; and disease duration ≤5 years. Participants are followed for 2 years, with three annual assessments at the study center. Outcomes include a clinical assessment (including motor and neuro-psychological tests), collection of biospecimens (stool, whole blood, and cerebrospinal fluid), magnetic resonance imaging (both structural and functional), and ECG recordings (both 12-lead and Holter). Additionally, collection of physiological and environmental data in daily life over 2 years will be enabled through the Verily Study Watch. All data are stored with polymorphic encryptions and pseudonyms, to guarantee the participants' privacy on the one hand, and to enable data sharing on the other. The data and biospecimens will become available for scientists to address Parkinson's disease-related research questions.

DISCUSSION

The PPP has several distinguishing elements: all assessments are done in a single center; inclusion of "real life" subjects; deep and repeated multi-dimensional phenotyping; and continuous monitoring with a wearable device for 2 years. Also, the PPP is powered by privacy and security by design, allowing for data sharing with scientists worldwide respecting participants' privacy. The data are expected to open the way for important new insights, including identification of biomarkers to predict differences in prognosis and treatment response between patients. Our long-term aim is to improve existing treatments, develop new therapeutic approaches, and offer Parkinson's disease patients a more personalized disease management approach.

TRIAL REGISTRATION

Clinical Trials NCT03364894 . Registered December 6, 2017 (retrospectively registered).

Nicotine prevents alpha-synuclein accumulation in mouse and human iPSC-derived dopaminergic neurons through activation of the dopamine D3- acetylcholine nicotinic receptor heteromer

We recently found that in mouse dopaminergic neurons, the heteromer formed by the dopamine D3 receptor (D3R) and the β2 subunit of acetylcholine nicotinic receptor (nAChR) exerts neurotrophic effects when activated by nicotine, leading to neurons with enlarged cell bodies and increased dendrite arborization. Beside this action, we now show that nicotine, by activating the D3R-nAChR heteromer, protects dopaminergic neurons against neuronal injury. In primary cultures of mouse dopaminergic neurons, in fact, the ability of nicotine to inhibit both the pathological accumulation of alpha-synuclein induced by glucose deprivation and the consequent morphological defects were strongly prevented by disrupting the D3R-nAChR heteromer with specific interfering TAT-peptides; the relevance of the phosphoinositide 3-kinase (PI3K) intracellular signaling in mediating nicotine prevention of alpha-synuclein aggregation has been also demonstrated. Moreover, the ability of nicotine in restoring the ubiquitin-proteasome system has been found as a mechanism contributing to the neuroprotective properties of nicotine. By using the proximity ligation assay, we have shown that the D3R-nAChR heteromer is also expressed in human dopaminergic neurons derived from induced pluripotent stem cells. In this human cell model, nicotine exerts neuroprotective effects specifically acting through the D3R-nAChR complex thus indicating that this heteromer is a relevant molecular effector involved in the protection of human dopaminergic neurons.

Association of statin use with Parkinson's disease: Dose-response relationship

BACKGROUND

There have been conflicting results on the association between statin use and Parkinson's disease (PD) incidence.

OBJECTIVES

This study investigated the association between time-varying status of statin use and incidence of PD while considering the dose-response relationship and total cholesterol level.

METHODS

Using the database of the Korean National Health Insurance Service from 2002 to 2015, we examined 76,043 subjects (≥60 years old) free of PD, dementia, and stroke at baseline. The dose of statin use was classified into the following four 6-month categories (<180, 180-365, 365-540, and ≥540 days) for each 2-year interval. The incidence of PD was identified by the prescription records for any anti-PD medication with a diagnosis of PD.

RESULTS

During 10 years of follow-up, 1,427 PD cases occurred. Statin "ever use" was significantly associated with a high risk of PD incidence (adjusted hazard ratio = 1.28; 95% confidence interval = 1.12-1.46) when compared with statin nonuse. In terms of a dose-response relationship, although a duration of statin use <365 days was associated with a higher risk of PD, the duration of statin use ≥365 days was not significantly associated with an increased risk of PD.

CONCLUSIONS

Statin use was associated with an elevated PD risk of PD, but long-term and adherent statin use was not significantly associated with elevated PD risk. However, there was no evidence of benefit with any statin treatment related to PD risk. Our study suggests that there is a complex relationship among cholesterol level, statin use, and PD risk that warrants further studies. © 2019 International Parkinson and Movement Disorder Society.

Trehalose as a promising therapeutic candidate for the treatment of Parkinson's disease

Parkinson's disease (PD) is a progressive movement disorder resulting primarily from loss of nigrostriatal dopaminergic neurons. PD is characterized by the accumulation of protein aggregates, and evidence suggests that aberrant protein deposition in dopaminergic neurons could be related to the dysregulation of the lysosomal autophagy pathway. The therapeutic potential of autophagy modulators has been reported in experimental models of PD. Trehalose is a natural disaccharide that has been considered as a new candidate for the treatment of neurodegenerative diseases. It has a chaperone-like activity, prevents protein misfolding or aggregation, and by promoting autophagy, contributes to the removal of accumulated proteins. In this review, we briefly summarize the role of aberrant autophagy in PD and the underlying mechanisms that lead to the development of this disease. We also discuss reports that used trehalose to counteract the neurotoxicity in PD, focusing particularly on the autophagy promoting, protein stabilization, and anti-neuroinflammatory effects of trehalose.

Plant Extracts and Phytochemicals Targeting α-Synuclein Aggregation in Parkinson's Disease Models

α-Synuclein (α-syn) is a presynaptic protein that regulates the release of neurotransmitters from synaptic vesicles in the brain. α-Syn aggregates, including Lewy bodies, are features of both sporadic and familial forms of Parkinson's disease (PD). These aggregates undergo several key stages of fibrillation, oligomerization, and aggregation. Therapeutic benefits of drugs decline with disease progression and offer only symptomatic treatment. Novel therapeutic strategies are required which can either prevent or delay the progression of the disease. The link between α-syn and the etiopathogenesis and progression of PD are well-established in the literature. Studies indicate that α-syn is an important therapeutic target and inhibition of α-syn aggregation, oligomerization, and fibrillation are an important disease modification strategy. However, recent studies have shown that plant extracts and phytochemicals have neuroprotective effects on α-syn oligomerization and fibrillation by targeting different key stages of its formation. Although many reviews on the antioxidant-mediated, neuroprotective effect of plant extracts and phytochemicals on PD symptoms have been well-highlighted, the antioxidant mechanisms show limited success for translation to clinical studies. The identification of specific plant extracts and phytochemicals that target α-syn aggregation will provide selective molecules to develop new drugs for PD. The present review provides an overview of plant extracts and phytochemicals that target α-syn in PD and summarizes the observed effects and the underlying mechanisms. Furthermore, we provide a synopsis of current experimental models and techniques used to evaluate plant extracts and phytochemicals. Plant extracts and phytochemicals were found to inhibit the aggregation or fibril formation of oligomers. These also appear to direct α-syn oligomer formation into its unstructured form or promote non-toxic pathways and suggested to be valuable drug candidates for PD and related synucleinopathy. Current evidences from in vitro studies require confirmation in the in vivo studies. Further studies are needed to ascertain their potential effects and safety in preclinical studies for pharmaceutical/nutritional development of these phytochemicals or dietary inclusion of the plant extracts in PD treatment.

Dopamine compartmentalization, selective dopaminergic vulnerabilities in Parkinson's disease and therapeutic opportunities

Progressive depletion of selected dopamine neurons is central to much Parkinson's disease (PD) disability. Although symptomatic treatments can ameliorate the disabilities that this neuronal depletion causes, no current strategy is documented to slow these losses. There is substantial evidence that dopamine in intracytoplasmic/extravesicular neuronal compartments can be toxic. Here, I review evidence that supports roles for dopamine compartmentalization, mediated largely by serial actions of plasma membrane SLC6A3/DAT and vesicular SLC18A2/VMAT2 transporters, in the selective patterns of dopamine neuronal loss found in PD brains. This compartmentalization hypothesis for the dopamine cell type specificity of PD lesions nominates available drugs for amelioration of damage arising from miscompartmentalized dopamine and raises cautions in using other drugs.

Societal Burden and Persisting Unmet Needs of Parkinson’s Disease

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Protein variability in cerebrospinal fluid and its possible implications for neurological protein biomarker research

Cerebrospinal fluid is investigated in biomarker studies for various neurological disorders of the central nervous system due to its proximity to the brain. Currently, only a limited number of biomarkers have been validated in independent studies. The high variability in the protein composition and protein abundance of cerebrospinal fluid between as well as within individuals might be an important reason for this phenomenon. To evaluate this possibility, we investigated the inter- and intraindividual variability in the cerebrospinal fluid proteome globally, with a specific focus on disease biomarkers described in the literature. Cerebrospinal fluid from a longitudinal study group including 12 healthy control subjects was analyzed by label-free quantification (LFQ) via LC-MS/MS. Data were quantified via MaxQuant. Then, the intra- and interindividual variability and the reference change value were calculated for every protein. We identified and quantified 791 proteins, and 216 of these proteins were abundant in all samples and were selected for further analysis. For these proteins, we found an interindividual coefficient of variation of up to 101.5% and an intraindividual coefficient of variation of up to 29.3%. Remarkably, these values were comparably high for both proteins that were published as disease biomarkers and other proteins. Our results support the hypothesis that natural variability greatly impacts cerebrospinal fluid protein biomarkers because high variability can lead to unreliable results. Thus, we suggest controlling the variability of each protein to distinguish between good and bad biomarker candidates, e.g., by utilizing reference change values to improve the process of evaluating potential biomarkers in future studies.

Cerebrospinal Fluid Levels of Autophagy-related Proteins Represent Potentially Novel Biomarkers of Early-Stage Parkinson's Disease

The roles of autophagy-related proteins as diagnostic or monitoring biomarkers in Parkinson's disease (PD) have not been clearly elucidated. We recruited 32 patients with early-stage PD and 28 control subjects, and evaluated parkinsonian motor symptoms and dopamine transporter imaging data. Cerebrospinal fluid (CSF) levels of LC3B, Beclin1, and LAMP-2 were estimated using ELISAs, and CSF levels of ATG5, ATG7, and p62 were examined by immunoblotting. Additionally, we also assessed the levels of α-synuclein, total tau, and phosphorylated tau in CSF using ELISAs. Significant differences in the levels of LC3B, LAMP-2, and Beclin1 were observed between the PD and control groups. Using 29.8 pg/mL as the cut-off value for a diagnostic biomarker of PD, CSF LC3B levels exhibited high sensitivity (96.9%) and specificity (89.3%) with an area under the curve of 0.982. Furthermore, LC3B was significantly correlated with the asymmetry index in the caudate and putamen, as estimated by a semi-quantitative analysis of [¹⁸F] N-(3-fluoropropyl)-2β-carbon ethoxy-3β-(4-iodophenyl) nortropane (FP-CIT) positron emission tomography (PET). CSF levels of LC3B represented a potential diagnostic and prognostic biomarker of early-stage PD in patients. Based on our findings, molecular biological changes in PD are associated with dysregulation of the lysosomal autophagy pathway.

Herbal Medicine Formulas for Parkinson's Disease: A Systematic Review and Meta-Analysis of Randomized Double-Blind Placebo-Controlled Clinical Trials

Background: Parkinson's disease (PD) is a debitlitating, chronic, progressive neurodegenerative disorder without modifying therapy. Here, we aimed to evaluate the available evidence of herbal medicine (HM) formulas for patients with PD according to randomized double-blind placebo-controlled clinical trials. Methods: HM formulas for PD were searched in eight main databases from their inception to February 2018. The methodological quality was assessed using Cochrane Collaboration risk of bias tool. Meta-analysis was performed using RevMan 5.3 software. Results: Fourteen trials with Seventeen comparisons comprising 1,311 patients were identified. Compared with placebo groups, HM paratherapy (n = 16 comparisons) showed significant better effects in the assessments of total Unified Parkinson's Disease Rating Scale (UPDRS) (WMD: -5.43, 95% CI:-8.01 to -2.86; P < 0.0001), UPDRS I (WMD: -0.30, 95% CI: -0.54 to -0.06; P = 0.02), UPDRS II (WMD: -2.21, 95% CI: -3.19 to -1.22; P < 0.0001), UPDRS III (WMD: -3.26, 95% CI:-4.36 to -2.16; P < 0.00001), Parkinson's Disease Quality of Life Questionnaire (p < 0.01) and Parkinson's Disease Questionnaire-39 (WMD: -7.65, 95% CI: -11.46 to -3.83; p < 0.0001), Non-motor Symptoms Questionnaire (p < 0.01) and Non-Motor Symptoms Scale (WMD: -9.19, 95% CI: -13.11 to -5.28; P < 0.00001), Parkinson's Disease Sleep Scale (WMD: 10.69, 95% CI: 8.86 to 12.53; P < 0.00001), and Hamilton depression rating scale (WMD: -5.87, 95% CI: -7.06 to -4.68; P < 0.00001). The efficiency of HM monotherapy (n = 1 comparison) was not superior to the placebo according to UPDRS II, UPDRS III and total UPDRS score in PD patients who never received levodopa treatment, all P > 0.05. HM formulas paratherapy were generally safe and well tolerated for PD patients (RR: 0.41, 95% CI: 0.21 to 0.80; P = 0.009). Conclusion: The findings of present study supported the complementary use of HM paratherapy for PD patients, whereas the question on the efficacy of HM monotherapy in alleviating PD symptoms is still open.

Outside in: Unraveling the Role of Neuroinflammation in the Progression of Parkinson's Disease

Neuroinflammation is one of the most important processes involved in the pathogenesis of Parkinson's disease (PD). The current concept of neuroinflammation comprises an inflammation process, which occurs in the central nervous system due to molecules released from brain-resident and/or blood-derived immune cells. Furthermore, the evidence of the contribution of systemic delivered molecules to the disease pathogenesis, such as the gut microbiota composition, has been increasing during the last years. Under physiological conditions, microglia and astrocytes support the well-being and well-function of the brain through diverse functions, including neurotrophic factor secretion in both intact and injured brain. On the other hand, genes that cause PD are expressed in astrocytes and microglia, shifting their neuroprotective role to a pathogenic one, contributing to disease onset and progression. In addition, growth factors are a subset of molecules that promote cellular survival, differentiation and maturation, which are critical signaling factors promoting the communication between cells, including neurons and blood-derived immune cells. We summarize the potential targeting of astrocytes and microglia and the systemic contribution of the gut microbiota in neuroinflammation process archived in PD.